The accurate diagnosis of meniscal and cruciate ligament tears is essential for proper management... more The accurate diagnosis of meniscal and cruciate ligament tears is essential for proper management of knee injuries. In recent years, magnetic resonance imaging has been increasingly used to diagnose knee pathology. Several articles have documented the accuracy of MRI, but conflicting results have been reported. We present a series of 50 consecutive patients who underwent both MRI and complete arthroscopy. We tested two different scanning protocols and found the higher-resolution scanning protocol to be more accurate, resulting in fewer discrepancies between the results of MRI and arthroscopy, which we used as the standard for comparing the MRI interpretations. Magnetic resonance imaging is an important diagnostic tool in orthopedic practice. It is available, accurate, and well-accepted by patients. However, as demonstrated by the results of this study, the accuracy of MRI is highly dependent upon the scanning protocol used.
American journal of orthopedics (Belle Mead, N.J.)
When a blow to the sternum causes pain in a young athlete, the differential diagnosis can be comp... more When a blow to the sternum causes pain in a young athlete, the differential diagnosis can be complicated by persistence of an unfused growth center that does not normally fuse until age 18. We report a case of physeal injury in the sternum that was originally diagnosed as a stress fracture. The young football player in this case may have been predisposed to such an injury by abnormal synostosis of the sternomanubrial junction.
Occult osseous lesions occurring with anterior cruciate ligament tears have been described only r... more Occult osseous lesions occurring with anterior cruciate ligament tears have been described only recently. Twenty patients with complete anterior cruciate ligament disruptions and evidence of occult osseous lesions on their preoperative magnetic resonance (MR) images were evaluated retrospectively at 24- to 73-months' followup to document the natural history and long-term effects of the lesions. Thirty-seven initial osseous signal abnormalities were documented on the MR images of 20 patients. All 20 patients had lesions in the posterolateral tibial plateau, and 13 had additional lesions in the lateral femoral condyle. Twenty-four of the 37 osseous lesions appeared resolved on followup MR images, and 13 had become sclerotic. Lesions of the lateral tibial plateau were especially likely to be sclerotic at followup. This study reaffirms the specificity of bone signal abnormalities of the posterolateral tibial plateau and lateral femoral condyle in association with complete anterior cruciate ligament tears. The data indicate that a proportion of anterior cruciate ligament patients will incur progressive articular cartilage abnormalities, although case-by-case predictions based on initial MR images would be unreliable.
The ideal treatment for patients presenting with bilateral anterior cruciate ligament (ACL) defic... more The ideal treatment for patients presenting with bilateral anterior cruciate ligament (ACL) deficiency remains controversial. To evaluate cost and early functional results after bilateral ACL reconstruction at a single setting. Retrospective review. Eleven patients (22 knees) who underwent bilateral ACL reconstruction at a single setting were compared with 33 patients (35 knees) who underwent unilateral ACL reconstruction during the same time period. The mean time to full unrestricted activity between groups was 6.5 months for both groups (P = 0.92). There were no significant differences between groups at latest follow-up for complication rates or laxity as judged by Lachman test, pivot shift test, and KT 1000 arthrometry. The mean International Knee Documentation Committee subjective score at a mean 3.1-year follow-up was 91.9 for the bilateral ACL group compared to 92.0 for the unilateral ACL group (P = 0.95). There was a total cost savings per knee (based on 2001 dollars) of $3751.59 when performing bilateral ACL reconstruction at a single setting (P = 0.0001). For patients presenting with bilateral ACL deficient knees, reconstruction of both knees at a single setting is safe, cost effective, and does not appear to compromise early functional results.
One of the more-serious side effects of extended space flight is an accelerated bone loss [Bioast... more One of the more-serious side effects of extended space flight is an accelerated bone loss [Bioastronautics Critical Path Roadmap, http://research.hq.nasa.gov/code_u/bcpr/index.cfm]. Rates of bone loss are highest in the weight-bearing bones of the hip and spine regions, and the average rate of bone loss as measured by bone mineral density measurements is around 1.2% per month for persons in a microgravity environment. It shows that an extrapolation of the microgravity induced bone loss rates to longer time scales, such as a 2.5 year round-trip to Mars (6 months out at 0 g, 1.5 year stay on Mars at 0.38 g, 6 months back at 0 g), could severely compromise the skeletal system of such a person.
To assess the character and cause of photopsias in vitreoretinal patients. Cross-sectional study.... more To assess the character and cause of photopsias in vitreoretinal patients. Cross-sectional study. A total of 169 consecutive patients (217 eyes) with vitreoretinal disease presenting with a history of photopsias. A total of 217 eyes with photopsias in 169 patients were evaluated. Photopsia assessment included (1) laterality (unilateral, bilateral but not simultaneous, bilateral, and simultaneous); (2) morphology (flash, zig-zag, strobe, scintillating scotoma, twinkling, other); (3) color (white, silver, yellow, combination, other); (4) location (temporal, central, other); (5) duration (quick, prolonged, constant, other); (6) frequency; (7) diurnal appearance (day, night, both); (8) stimuli (turning head or eyes, hypoglycemia, hyperglycemia, other); and (9) associated systemic or ocular signs and symptoms (headache, numbness, weakness, vertigo, syncope, diplopia, hypotension, floaters, other). Clinical photopsia features correlated with the causes of photopsias. Thirty-two photopsia causes were identified. The top 16 included posterior vitreous detachment (PVD) in 39.7% of eyes; retinal tear in 8.9% of eyes; neovascular age-related macular degeneration (AMD) in 7.9% of eyes; rhegmatogenous retinal detachment (RRD) in 7.5% of eyes; classic and ophthalmic migraine in 6.5% of eyes; hypoglycemia in 2.8% of eyes; vertebrobasilar insufficiency in 2.8% of eyes; non-AMD choroidal neovascularization in 2.3% of eyes; retinitis pigmentosa in 1.9% of eyes; severe cough in 1.9% of eyes; central serous chorioretinopathy in 1.4% of eyes; intraocular lens reflections in 0.9% of eyes; blue field entoptic phenomenon in 0.9% of eyes; Charles Bonnet syndrome in 0.9% of eyes; digitalis in 0.9% of eyes; and metastatic adenocarcinoma to the brain in 0.9% of eyes. The photopsias associated with PVD are typically quick (96%), with lightning/flash morphology (96%), white (87%), temporally located (86%), associated with new-onset floaters (85%), preferentially seen in dark (90%) rather than lighted environments (29%), and often initiated by head/eye movements (60%). Retinal detachment had a similar profile, but with more nontemporal photopsias (40%) (P = 0.01). The photopsias from neovascular AMD are more centrally located (83%), quick and repetitive (79%), seen in light (73%) and dark (63%) environments, have no inciting stimuli (84%), and are more likely to be nonwhite (40%). A pointed history for photopsias can reveal a cause that may not initially seem apparent. Thus, the history can play a key role in management decisions.
This study details six instances of refracture of clinically and radiographically healed fracture... more This study details six instances of refracture of clinically and radiographically healed fractures of the base of the fifth metatarsal after intramedullary screw fixation. Four professional football players, one college basketball player, and one recreational athlete underwent intramedullary screw fixation of fifth metatarsal fractures. The athletes were released to full activities an average of 8.5 weeks (range, 5.5 to 12) after fixation, when healing was clinically and radiographically documented. Three football players developed refracture within 1 day of return to full activity. The other three athletes refractured at 2.5, 4, and 4.5 months after return to activity. Two football players underwent repeat fixation with larger screws and returned to play in the same season. The college basketball player underwent bone grafting and returned to play in subsequent seasons. The other three athletes underwent nonoperative management and healed uneventfully over 6 to 8 weeks. On the basi...
A prospective randomized trial of low versus high doses of human leukocyte alpha-interferon (1 X ... more A prospective randomized trial of low versus high doses of human leukocyte alpha-interferon (1 X 10(6) units/day for 28 days versus 10 X 10(6) units/day for 28 days) was carried out in 30 patients with metastatic renal cell carcinoma, to test the tolerance and relative antitumor effects of these interferon doses. Both doses were tolerated well, and responses to the human leukocyte alpha-interferon were observed overall in seven individuals, including complete, partial, and minimal tumor regressions. Six of the seven responses occurred in patients who received the high dosage, and three of these responses were major responses. While not statistically significant, this result suggested a dose-response relationship. One minimal response was observed in a patient treated at low dosage. Nine individuals who were stable after 1 month of therapy at low dosage were randomized to a further month of therapy at low or high dosage, during which one of four at high dosage had a partial response,...
Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing VI, 1999
ABSTRACT Calibration of the axial response of interference microscopes has received considerable ... more ABSTRACT Calibration of the axial response of interference microscopes has received considerable attention in the past two decades. In addition to systematic errors which could be caused by components in the microscope or measurement technique, a numerical correction factor associated with imaging at high apertures must be determined. Unfortunately, the cost of reference height standards increases sharply with their spatial homogeneity and calibration accuracy and these standards may be easily contaminated and therefore require sophisticated cleaning and re-calibration. To address these problems, we have investigated the interferometric measurement of the equilibrium shape of static fluid drops on coated substrates. For drops with small Bond number (the Bond number is a ratio of gravitational to capillary forces), the surface of the drop forms a spherical cap. It appears that nature forms a highly smooth, curved surface. By varying the surface energy, it is possible to obtain a wide range of static contact angles. For example, silicone oil [polydimethylsiloxane (PDMS)] on glass forms a contact angle of about 5 degrees, while it forms an angle of 38 degrees on Teflon and 68 degrees on a fluorinated silicon surface. We have measured contact angles as large as 68 degrees for PDMS on a single crystal silicon wafer with a 50 X/0.8 NA objective using a custom-made phase-shifted, laser feedback microscope. The method for preparing these static drops is simple and we envision that microscopists will be able to prepare easily disposable calibration standards in their laboratories.
Severe quadriceps muscle contusions in athletes are enigmatic in several respects. Immediately af... more Severe quadriceps muscle contusions in athletes are enigmatic in several respects. Immediately after injury an athlete may have negligible symptoms, but development of morbidity over the ensuing 24 hours may include swelling, limited range of knee motion, and pain. ...
Coherence Domain Optical Methods in Biomedical Science and Clinical Applications V, 2001
ABSTRACT We demonstrate the use of phase-shifting interferometry in OCT to determine the optical ... more ABSTRACT We demonstrate the use of phase-shifting interferometry in OCT to determine the optical phase and fringe visibility within the coherence envelope. Phase-shifting algorithms provide both the optical phase and visibility from a series of intensity measurements corresponding to controlled phase shifts. In addition to providing phase information which supplements the visibility or envelope data which is traditionally obtained in OCT, this technique will provide an independent, highly sensitive measurement of the coherence envelope which may be used for a precise determination of the source power spectrum.
ABSTRACT We have developed a model that predicts the effective optical path length (OPL) through ... more ABSTRACT We have developed a model that predicts the effective optical path length (OPL) through a thick, refractive specimen on a reflective substrate as measured with a high numerical aperture, confocal interference microscope. Assuming an infinitesimal pinhole, only one 'magic ray' contributes to the measured OPL. It is possible to correct for the refractive errors and to unambiguously interpret the data. We present a comparison of our model predictions with experimental measurements of a fluid drop on a silicon substrate, obtained with a phase shifting laser feedback microscope.
Propionibacterium acnes endophthalmitis after cataract extraction and posterior chamber intraocul... more Propionibacterium acnes endophthalmitis after cataract extraction and posterior chamber intraocular lens (IOL) implantation is characterized by a chronic indolent course, frequently associated with recurrence after standard endophthalmitis treatment. This study was designed to evaluate the efficacy of various therapeutic methods in the treatment of primary and recurrent episodes of postoperative P. acnes endophthalmitis. Retrospective, noncomparative case series. Twenty-five patients treated at Wills Eye Hospital for P. acnes endophthalmitis. The authors retrospectively reviewed the clinical charts and microbiology files of all patients treated at Wills Eye Hospital between January 1991 and April 1998 with culture-proven P. acnes endophthalmitis after cataract extraction and posterior chamber IOL implantation. Results of cultures and microbiologic examinations, efficacy of various treatment methods in the prevention of recurrent inflammatory episodes, and final visual outcome. Twenty-five patients who met inclusion criteria were identified; initial therapy consisted of 1 of the following: intraocular antibiotic (IOAB) injections alone (2 patients); IOAB combined with pars plana vitrectomy (PPV) (10 patients); IOAB and PPV combined with partial capsulectomy (9 patients); and IOAB, PPV, total capsulectomy, and IOL exchange (4 patients). Nearly half of the patients (10 of 21, or 48%) initially treated with IOAB alone (1 of 2), IOAB and PPV (5 of 10), and IOAB combined with PPV and partial capsulectomy (4 of 9) required further therapeutic interventions for recurrent disease. Retreatment with IOAB alone or combined with PPV and partial capsulectomy in these patients failed to eradicate the infection in three (75%) of four patients. None of the patients (0 of 4) treated initially with total capsulectomy and IOL exchange required additional surgical intervention. Furthermore, none of the patients (0 of 13) who underwent total capsulectomy with IOL removal or exchange or IOL exchange alone as an initial, secondary, or tertiary treatment required further intervention. In the authors' series, approximately half of the patients with P. acnes endophthalmitis were treated successfully initially with nonsurgical or limited surgical intervention. All patients treated with total capsulectomy and IOL exchange or removal, either as an initial treatment or for recurrent disease, were cured. Removal of the entire capsular bag and the IOL may be performed as a definitive initial therapy and should be performed for recurrent inflammation.
A series of 24 consecutive patients presenting with a fundus picture characterized by a predomina... more A series of 24 consecutive patients presenting with a fundus picture characterized by a predominance of cotton-wool spots, or a single cotton-wool spot, is reported. Excluded were patients with known diabetes mellitus. Etiologic conditions found included previously undiagnosed diabetes mellitus in five patients, systemic hypertension in five patients, cardiac valvular disease in two patients, radiation retinopathy in two patients, and severe carotid artery obstruction in two patients. Dermatomyositis, systemic lupus erythematosus, polyarteritis nodosa, leukemia, AIDS, Purtscher's retinopathy, metastatic carcinoma, intravenous drug abuse, partial central retinal artery obstruction, and giant cell arteritis were each found in one patient. In only one patient did a systemic workup fail to reveal an underlying cause. The presence of even one cotton-wool spot in an otherwise normal fundus necessitates an investigation to ascertain systemic etiologic factors.
A novel method is described for measuring the deformability of red blood cells (RBCs) in tubing w... more A novel method is described for measuring the deformability of red blood cells (RBCs) in tubing whose diameters approximate forces encountered in vivo. Here, RBCs from rabbits are loaded into a 50 cm section of 75 microm id microbore tubing and connected to a syringe pump. This section of tubing is then connected to a 15 cm section of 25 microm id tubing. As buffer is pumped through the flow system, the RBCs are evacuated from both sections of tubing. However, the inability of the RBCs to move freely through the 25 mirom id section of tubing results in a buildup of cells at the inlet of this portion of tubing. The continued force output by the syringe pump results in a deformation of the RBCs until all of the cells are eventually evacuated from the flow system. It was found that a measurement of the time required to reach half of the maximum pressure (1/2 P(max)) may be used as an indicator of the RBC deformability. For a given sample, a simple buffer results in less time to reach 1/2 P(max) (6.9 +/- 0.2 s) than deformable RBCs (21.6 +/- 0.8 s). To verify that the increased amount of time to reach 1/2 P(max) is indeed due to the RBCs, various hematocrits of an RBC sample were investigated and, as expected, it was found that a 12% RBC hematocrit had a higher 1/2 P(max) value (26.0 s +/- 2.2 s) when compared to a 7% hematocrit (19.1 +/- 0.3 s). In addition, RBCs chemically stiffened with glutaraldehyde were shown to be 25% less deformable than normal RBCs. Finally, a study was performed to examine the relationship between RBC deformability and ATP release and it was found that ATP release increased as a function of RBC deformability. This method greatly simplifies deformability measurements, employing only a syringe pump and microbore tubing, and may lead to a more complete understanding of the physiological significance of erythrocyte deformability.
The most common pathogen to cause endogenous endophthalmitis is the fungus Candida albicans. Most... more The most common pathogen to cause endogenous endophthalmitis is the fungus Candida albicans. Most cases involve adults who are either immunosuppressed or have a history of repeated or prolonged extracorporeal access to their circulatory system. Endogenous Candida endophthalmitis can occur in infants as well, particularly when prematurity, broad spectrum antibiotic therapy, or prior surgery are present as predisposing factors. We report the clinical and histopathological findings of an infant who developed a unilateral, sectoral lens opacity four months after undergoing treatment for disseminated candidiasis. The diagnosis of localized intralenticular fungal abscess with associated endophthalmitis was made via histopathologic examination of the aspirated lens material. Treatment with systemic antifungal agents successfully preserved the eye. In addition, we review and summarize the previously reported cases of Candida endophthalmitis in patients under one year of age.
The accurate diagnosis of meniscal and cruciate ligament tears is essential for proper management... more The accurate diagnosis of meniscal and cruciate ligament tears is essential for proper management of knee injuries. In recent years, magnetic resonance imaging has been increasingly used to diagnose knee pathology. Several articles have documented the accuracy of MRI, but conflicting results have been reported. We present a series of 50 consecutive patients who underwent both MRI and complete arthroscopy. We tested two different scanning protocols and found the higher-resolution scanning protocol to be more accurate, resulting in fewer discrepancies between the results of MRI and arthroscopy, which we used as the standard for comparing the MRI interpretations. Magnetic resonance imaging is an important diagnostic tool in orthopedic practice. It is available, accurate, and well-accepted by patients. However, as demonstrated by the results of this study, the accuracy of MRI is highly dependent upon the scanning protocol used.
American journal of orthopedics (Belle Mead, N.J.)
When a blow to the sternum causes pain in a young athlete, the differential diagnosis can be comp... more When a blow to the sternum causes pain in a young athlete, the differential diagnosis can be complicated by persistence of an unfused growth center that does not normally fuse until age 18. We report a case of physeal injury in the sternum that was originally diagnosed as a stress fracture. The young football player in this case may have been predisposed to such an injury by abnormal synostosis of the sternomanubrial junction.
Occult osseous lesions occurring with anterior cruciate ligament tears have been described only r... more Occult osseous lesions occurring with anterior cruciate ligament tears have been described only recently. Twenty patients with complete anterior cruciate ligament disruptions and evidence of occult osseous lesions on their preoperative magnetic resonance (MR) images were evaluated retrospectively at 24- to 73-months' followup to document the natural history and long-term effects of the lesions. Thirty-seven initial osseous signal abnormalities were documented on the MR images of 20 patients. All 20 patients had lesions in the posterolateral tibial plateau, and 13 had additional lesions in the lateral femoral condyle. Twenty-four of the 37 osseous lesions appeared resolved on followup MR images, and 13 had become sclerotic. Lesions of the lateral tibial plateau were especially likely to be sclerotic at followup. This study reaffirms the specificity of bone signal abnormalities of the posterolateral tibial plateau and lateral femoral condyle in association with complete anterior cruciate ligament tears. The data indicate that a proportion of anterior cruciate ligament patients will incur progressive articular cartilage abnormalities, although case-by-case predictions based on initial MR images would be unreliable.
The ideal treatment for patients presenting with bilateral anterior cruciate ligament (ACL) defic... more The ideal treatment for patients presenting with bilateral anterior cruciate ligament (ACL) deficiency remains controversial. To evaluate cost and early functional results after bilateral ACL reconstruction at a single setting. Retrospective review. Eleven patients (22 knees) who underwent bilateral ACL reconstruction at a single setting were compared with 33 patients (35 knees) who underwent unilateral ACL reconstruction during the same time period. The mean time to full unrestricted activity between groups was 6.5 months for both groups (P = 0.92). There were no significant differences between groups at latest follow-up for complication rates or laxity as judged by Lachman test, pivot shift test, and KT 1000 arthrometry. The mean International Knee Documentation Committee subjective score at a mean 3.1-year follow-up was 91.9 for the bilateral ACL group compared to 92.0 for the unilateral ACL group (P = 0.95). There was a total cost savings per knee (based on 2001 dollars) of $3751.59 when performing bilateral ACL reconstruction at a single setting (P = 0.0001). For patients presenting with bilateral ACL deficient knees, reconstruction of both knees at a single setting is safe, cost effective, and does not appear to compromise early functional results.
One of the more-serious side effects of extended space flight is an accelerated bone loss [Bioast... more One of the more-serious side effects of extended space flight is an accelerated bone loss [Bioastronautics Critical Path Roadmap, http://research.hq.nasa.gov/code_u/bcpr/index.cfm]. Rates of bone loss are highest in the weight-bearing bones of the hip and spine regions, and the average rate of bone loss as measured by bone mineral density measurements is around 1.2% per month for persons in a microgravity environment. It shows that an extrapolation of the microgravity induced bone loss rates to longer time scales, such as a 2.5 year round-trip to Mars (6 months out at 0 g, 1.5 year stay on Mars at 0.38 g, 6 months back at 0 g), could severely compromise the skeletal system of such a person.
To assess the character and cause of photopsias in vitreoretinal patients. Cross-sectional study.... more To assess the character and cause of photopsias in vitreoretinal patients. Cross-sectional study. A total of 169 consecutive patients (217 eyes) with vitreoretinal disease presenting with a history of photopsias. A total of 217 eyes with photopsias in 169 patients were evaluated. Photopsia assessment included (1) laterality (unilateral, bilateral but not simultaneous, bilateral, and simultaneous); (2) morphology (flash, zig-zag, strobe, scintillating scotoma, twinkling, other); (3) color (white, silver, yellow, combination, other); (4) location (temporal, central, other); (5) duration (quick, prolonged, constant, other); (6) frequency; (7) diurnal appearance (day, night, both); (8) stimuli (turning head or eyes, hypoglycemia, hyperglycemia, other); and (9) associated systemic or ocular signs and symptoms (headache, numbness, weakness, vertigo, syncope, diplopia, hypotension, floaters, other). Clinical photopsia features correlated with the causes of photopsias. Thirty-two photopsia causes were identified. The top 16 included posterior vitreous detachment (PVD) in 39.7% of eyes; retinal tear in 8.9% of eyes; neovascular age-related macular degeneration (AMD) in 7.9% of eyes; rhegmatogenous retinal detachment (RRD) in 7.5% of eyes; classic and ophthalmic migraine in 6.5% of eyes; hypoglycemia in 2.8% of eyes; vertebrobasilar insufficiency in 2.8% of eyes; non-AMD choroidal neovascularization in 2.3% of eyes; retinitis pigmentosa in 1.9% of eyes; severe cough in 1.9% of eyes; central serous chorioretinopathy in 1.4% of eyes; intraocular lens reflections in 0.9% of eyes; blue field entoptic phenomenon in 0.9% of eyes; Charles Bonnet syndrome in 0.9% of eyes; digitalis in 0.9% of eyes; and metastatic adenocarcinoma to the brain in 0.9% of eyes. The photopsias associated with PVD are typically quick (96%), with lightning/flash morphology (96%), white (87%), temporally located (86%), associated with new-onset floaters (85%), preferentially seen in dark (90%) rather than lighted environments (29%), and often initiated by head/eye movements (60%). Retinal detachment had a similar profile, but with more nontemporal photopsias (40%) (P = 0.01). The photopsias from neovascular AMD are more centrally located (83%), quick and repetitive (79%), seen in light (73%) and dark (63%) environments, have no inciting stimuli (84%), and are more likely to be nonwhite (40%). A pointed history for photopsias can reveal a cause that may not initially seem apparent. Thus, the history can play a key role in management decisions.
This study details six instances of refracture of clinically and radiographically healed fracture... more This study details six instances of refracture of clinically and radiographically healed fractures of the base of the fifth metatarsal after intramedullary screw fixation. Four professional football players, one college basketball player, and one recreational athlete underwent intramedullary screw fixation of fifth metatarsal fractures. The athletes were released to full activities an average of 8.5 weeks (range, 5.5 to 12) after fixation, when healing was clinically and radiographically documented. Three football players developed refracture within 1 day of return to full activity. The other three athletes refractured at 2.5, 4, and 4.5 months after return to activity. Two football players underwent repeat fixation with larger screws and returned to play in the same season. The college basketball player underwent bone grafting and returned to play in subsequent seasons. The other three athletes underwent nonoperative management and healed uneventfully over 6 to 8 weeks. On the basi...
A prospective randomized trial of low versus high doses of human leukocyte alpha-interferon (1 X ... more A prospective randomized trial of low versus high doses of human leukocyte alpha-interferon (1 X 10(6) units/day for 28 days versus 10 X 10(6) units/day for 28 days) was carried out in 30 patients with metastatic renal cell carcinoma, to test the tolerance and relative antitumor effects of these interferon doses. Both doses were tolerated well, and responses to the human leukocyte alpha-interferon were observed overall in seven individuals, including complete, partial, and minimal tumor regressions. Six of the seven responses occurred in patients who received the high dosage, and three of these responses were major responses. While not statistically significant, this result suggested a dose-response relationship. One minimal response was observed in a patient treated at low dosage. Nine individuals who were stable after 1 month of therapy at low dosage were randomized to a further month of therapy at low or high dosage, during which one of four at high dosage had a partial response,...
Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing VI, 1999
ABSTRACT Calibration of the axial response of interference microscopes has received considerable ... more ABSTRACT Calibration of the axial response of interference microscopes has received considerable attention in the past two decades. In addition to systematic errors which could be caused by components in the microscope or measurement technique, a numerical correction factor associated with imaging at high apertures must be determined. Unfortunately, the cost of reference height standards increases sharply with their spatial homogeneity and calibration accuracy and these standards may be easily contaminated and therefore require sophisticated cleaning and re-calibration. To address these problems, we have investigated the interferometric measurement of the equilibrium shape of static fluid drops on coated substrates. For drops with small Bond number (the Bond number is a ratio of gravitational to capillary forces), the surface of the drop forms a spherical cap. It appears that nature forms a highly smooth, curved surface. By varying the surface energy, it is possible to obtain a wide range of static contact angles. For example, silicone oil [polydimethylsiloxane (PDMS)] on glass forms a contact angle of about 5 degrees, while it forms an angle of 38 degrees on Teflon and 68 degrees on a fluorinated silicon surface. We have measured contact angles as large as 68 degrees for PDMS on a single crystal silicon wafer with a 50 X/0.8 NA objective using a custom-made phase-shifted, laser feedback microscope. The method for preparing these static drops is simple and we envision that microscopists will be able to prepare easily disposable calibration standards in their laboratories.
Severe quadriceps muscle contusions in athletes are enigmatic in several respects. Immediately af... more Severe quadriceps muscle contusions in athletes are enigmatic in several respects. Immediately after injury an athlete may have negligible symptoms, but development of morbidity over the ensuing 24 hours may include swelling, limited range of knee motion, and pain. ...
Coherence Domain Optical Methods in Biomedical Science and Clinical Applications V, 2001
ABSTRACT We demonstrate the use of phase-shifting interferometry in OCT to determine the optical ... more ABSTRACT We demonstrate the use of phase-shifting interferometry in OCT to determine the optical phase and fringe visibility within the coherence envelope. Phase-shifting algorithms provide both the optical phase and visibility from a series of intensity measurements corresponding to controlled phase shifts. In addition to providing phase information which supplements the visibility or envelope data which is traditionally obtained in OCT, this technique will provide an independent, highly sensitive measurement of the coherence envelope which may be used for a precise determination of the source power spectrum.
ABSTRACT We have developed a model that predicts the effective optical path length (OPL) through ... more ABSTRACT We have developed a model that predicts the effective optical path length (OPL) through a thick, refractive specimen on a reflective substrate as measured with a high numerical aperture, confocal interference microscope. Assuming an infinitesimal pinhole, only one 'magic ray' contributes to the measured OPL. It is possible to correct for the refractive errors and to unambiguously interpret the data. We present a comparison of our model predictions with experimental measurements of a fluid drop on a silicon substrate, obtained with a phase shifting laser feedback microscope.
Propionibacterium acnes endophthalmitis after cataract extraction and posterior chamber intraocul... more Propionibacterium acnes endophthalmitis after cataract extraction and posterior chamber intraocular lens (IOL) implantation is characterized by a chronic indolent course, frequently associated with recurrence after standard endophthalmitis treatment. This study was designed to evaluate the efficacy of various therapeutic methods in the treatment of primary and recurrent episodes of postoperative P. acnes endophthalmitis. Retrospective, noncomparative case series. Twenty-five patients treated at Wills Eye Hospital for P. acnes endophthalmitis. The authors retrospectively reviewed the clinical charts and microbiology files of all patients treated at Wills Eye Hospital between January 1991 and April 1998 with culture-proven P. acnes endophthalmitis after cataract extraction and posterior chamber IOL implantation. Results of cultures and microbiologic examinations, efficacy of various treatment methods in the prevention of recurrent inflammatory episodes, and final visual outcome. Twenty-five patients who met inclusion criteria were identified; initial therapy consisted of 1 of the following: intraocular antibiotic (IOAB) injections alone (2 patients); IOAB combined with pars plana vitrectomy (PPV) (10 patients); IOAB and PPV combined with partial capsulectomy (9 patients); and IOAB, PPV, total capsulectomy, and IOL exchange (4 patients). Nearly half of the patients (10 of 21, or 48%) initially treated with IOAB alone (1 of 2), IOAB and PPV (5 of 10), and IOAB combined with PPV and partial capsulectomy (4 of 9) required further therapeutic interventions for recurrent disease. Retreatment with IOAB alone or combined with PPV and partial capsulectomy in these patients failed to eradicate the infection in three (75%) of four patients. None of the patients (0 of 4) treated initially with total capsulectomy and IOL exchange required additional surgical intervention. Furthermore, none of the patients (0 of 13) who underwent total capsulectomy with IOL removal or exchange or IOL exchange alone as an initial, secondary, or tertiary treatment required further intervention. In the authors' series, approximately half of the patients with P. acnes endophthalmitis were treated successfully initially with nonsurgical or limited surgical intervention. All patients treated with total capsulectomy and IOL exchange or removal, either as an initial treatment or for recurrent disease, were cured. Removal of the entire capsular bag and the IOL may be performed as a definitive initial therapy and should be performed for recurrent inflammation.
A series of 24 consecutive patients presenting with a fundus picture characterized by a predomina... more A series of 24 consecutive patients presenting with a fundus picture characterized by a predominance of cotton-wool spots, or a single cotton-wool spot, is reported. Excluded were patients with known diabetes mellitus. Etiologic conditions found included previously undiagnosed diabetes mellitus in five patients, systemic hypertension in five patients, cardiac valvular disease in two patients, radiation retinopathy in two patients, and severe carotid artery obstruction in two patients. Dermatomyositis, systemic lupus erythematosus, polyarteritis nodosa, leukemia, AIDS, Purtscher's retinopathy, metastatic carcinoma, intravenous drug abuse, partial central retinal artery obstruction, and giant cell arteritis were each found in one patient. In only one patient did a systemic workup fail to reveal an underlying cause. The presence of even one cotton-wool spot in an otherwise normal fundus necessitates an investigation to ascertain systemic etiologic factors.
A novel method is described for measuring the deformability of red blood cells (RBCs) in tubing w... more A novel method is described for measuring the deformability of red blood cells (RBCs) in tubing whose diameters approximate forces encountered in vivo. Here, RBCs from rabbits are loaded into a 50 cm section of 75 microm id microbore tubing and connected to a syringe pump. This section of tubing is then connected to a 15 cm section of 25 microm id tubing. As buffer is pumped through the flow system, the RBCs are evacuated from both sections of tubing. However, the inability of the RBCs to move freely through the 25 mirom id section of tubing results in a buildup of cells at the inlet of this portion of tubing. The continued force output by the syringe pump results in a deformation of the RBCs until all of the cells are eventually evacuated from the flow system. It was found that a measurement of the time required to reach half of the maximum pressure (1/2 P(max)) may be used as an indicator of the RBC deformability. For a given sample, a simple buffer results in less time to reach 1/2 P(max) (6.9 +/- 0.2 s) than deformable RBCs (21.6 +/- 0.8 s). To verify that the increased amount of time to reach 1/2 P(max) is indeed due to the RBCs, various hematocrits of an RBC sample were investigated and, as expected, it was found that a 12% RBC hematocrit had a higher 1/2 P(max) value (26.0 s +/- 2.2 s) when compared to a 7% hematocrit (19.1 +/- 0.3 s). In addition, RBCs chemically stiffened with glutaraldehyde were shown to be 25% less deformable than normal RBCs. Finally, a study was performed to examine the relationship between RBC deformability and ATP release and it was found that ATP release increased as a function of RBC deformability. This method greatly simplifies deformability measurements, employing only a syringe pump and microbore tubing, and may lead to a more complete understanding of the physiological significance of erythrocyte deformability.
The most common pathogen to cause endogenous endophthalmitis is the fungus Candida albicans. Most... more The most common pathogen to cause endogenous endophthalmitis is the fungus Candida albicans. Most cases involve adults who are either immunosuppressed or have a history of repeated or prolonged extracorporeal access to their circulatory system. Endogenous Candida endophthalmitis can occur in infants as well, particularly when prematurity, broad spectrum antibiotic therapy, or prior surgery are present as predisposing factors. We report the clinical and histopathological findings of an infant who developed a unilateral, sectoral lens opacity four months after undergoing treatment for disseminated candidiasis. The diagnosis of localized intralenticular fungal abscess with associated endophthalmitis was made via histopathologic examination of the aspirated lens material. Treatment with systemic antifungal agents successfully preserved the eye. In addition, we review and summarize the previously reported cases of Candida endophthalmitis in patients under one year of age.
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Papers by David Fischer