Cette invention concerne des procedes et des methodes permettant d'introduire des sondes ther... more Cette invention concerne des procedes et des methodes permettant d'introduire des sondes therapeutiques chez un patient. Des modes de realisation de cette invention comprennent un systeme d'introduction de sonde automatise et un guide d'introduction de sonde comprenant un manchon de guidage de sonde mobile; un element servant a positionner ledit manchon de guidage de sonde; et une unite de commande pouvant fonctionner pour recevoir une definition d'un site dans le corps d'un patient et pour commander le positionnement et l'orientation dudit manchon de facon qu'une sonde introduite a travers ledit manchon progresse en direction du site en question. Cette invention concerne egalement des applications de cryochirurgie.
Cette invention concerne des dispositifs et des methodes permettant de planifier et de superviser... more Cette invention concerne des dispositifs et des methodes permettant de planifier et de superviser une chirurgie mini-invasive. Cette invention apporte des ameliorations a des systemes de planification, de surveillance et de commande de cryochirurgie.
PURPOSE. To investigate the role of endogenously generated nitric oxide (NO) in the relaxation of... more PURPOSE. To investigate the role of endogenously generated nitric oxide (NO) in the relaxation of bovine iris sphincter. METHODS. Isolated bovine sphincters were mounted on an isometric tension apparatus. Contraction-relaxation response was elicited by electrical field stimulation (ES; 12 Hz, 50-msec duration, 70 -80 V). Relaxation was arbitrarily defined as maximal decrease of tension below prestimulation baseline after cessation of ES. We also determined the tissue levels of cyclic guanosine monophosphate (cGMP) by radioimmunoassay. RESULTS. ES produced a biphasic response: contraction followed by relaxation. After cessation of ES, the muscle relaxed to below the initial baseline tension. Tetrodotoxin (TTX) abolished most of the contraction and all the relaxation response. Atropine blocked most of the contraction component, leaving the relaxation component unchanged. Prazosin and bupranolol (␣ 1 -adrenergic and -adrenergic antagonists, respectively) also did not affect the relaxa...
Investigative Ophthalmology Amp Visual Science, Mar 1, 2000
PURPOSE. To investigate the role of endogenously generated nitric oxide (NO) in the relaxation of... more PURPOSE. To investigate the role of endogenously generated nitric oxide (NO) in the relaxation of bovine iris sphincter. METHODS. Isolated bovine sphincters were mounted on an isometric tension apparatus. Contraction-relaxation response was elicited by electrical field stimulation (ES; 12 Hz, 50-msec duration, 70-80 V). Relaxation was arbitrarily defined as maximal decrease of tension below prestimulation baseline after cessation of ES. We also determined the tissue levels of cyclic guanosine monophosphate (cGMP) by radioimmunoassay. RESULTS. ES produced a biphasic response: contraction followed by relaxation. After cessation of ES, the muscle relaxed to below the initial baseline tension. Tetrodotoxin (TTX) abolished most of the contraction and all the relaxation response. Atropine blocked most of the contraction component, leaving the relaxation component unchanged. Prazosin and bupranolol (␣ 1-adrenergic and -adrenergic antagonists, respectively) also did not affect the relaxation component of the response. Neither substance P nor its antagonist (N-acetyl-L-tryptophane 3,5-bis (trifluoromethyl)-benzyl ester; ATTB) inhibited or mimicked the response. The nitric oxide synthase (NOS) inhibitors N-nitro-Larginine methyl ester (L-NAME), N-nitro-L-arginine (L-NNA), and aminoguanidine dose-dependently inhibited the relaxation response by 50% to 70%. The free radical scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (carboxy-PTIO) and the guanylyl cyclase inhibitor methylene blue also abrogated 70% and 45% of the relaxation response, respectively. ES caused an increase in muscle cGMP from 2.3 Ϯ 0.3 to 3.9 Ϯ 0.5 picomoles per muscle. L-NNA or L-NAME significantly decreased the tissue cGMP content (to 1.2 Ϯ 0.1 picomoles per muscle) and prevented the increase caused by ES. CONCLUSIONS. The relaxation component of the iris sphincter response to ES is a distinct nonadrenergic, noncholinergic, ES-induced event. Most of the relaxation is mediated by the endogenously generated NO-guanylyl cyclase-cGMP cascade.
Diffusion Tensor Imaging (DTI) is used to characterize the diffusion properties of deviated white... more Diffusion Tensor Imaging (DTI) is used to characterize the diffusion properties of deviated white matter caused by brain tumors. DTI was recently shown to be very helpful in delineating white matter both within brain lesions and surrounding them. Displacement of white matter fibers may be one of the consequences of tumor growth adjacent to white matter. The combination of white matter mapping with DTI and gray matter mapping using functional MRI, in some cases, facilitated assessment of the relation between the shifted cortical areas and the corresponding white matter tracts. We found that the fractional anisotropy extracted from DTI is increased by 38% in areas of non-edematous shifted white matter fibers. By contrast, trace apparent diffusion coefficient (ADC) values in those areas were found to be similar to contralateral side and normal control values. Analysis of the three diffusion tensor eigenvalues revealed that the increase in the fractional anisotropy is a result of two processes. The first is the increase in the diffusion parallel to the fibers-λ 1 (by 18%), and the second is the decrease in the diffusion perpendicular to fibers-λ 3 (by 34%) as compared with the contralateral side. These opposing changes cause an increase in the diffusion anisotropy but no change in the trace ADC. It is suggested that the pressure caused by the tumor may lead to an increase in white matter fiber tension, thus causing an increase in λ 1. On the other hand, the same pressure causes increased fiber density per unit area, leading to a higher degree of restricted diffusion in the extracellular space and, hence, a reduction in λ 3 .
Diffusion Tensor Imaging (DTI) is used to characterize the diffusion properties of deviated white... more Diffusion Tensor Imaging (DTI) is used to characterize the diffusion properties of deviated white matter caused by brain tumors. DTI was recently shown to be very helpful in delineating white matter both within brain lesions and surrounding them. Displacement of white matter fibers may be one of the consequences of tumor growth adjacent to white matter. The combination of white matter mapping with DTI and gray matter mapping using functional MRI, in some cases, facilitated assessment of the relation between the shifted cortical areas and the corresponding white matter tracts. We found that the fractional anisotropy extracted from DTI is increased by 38% in areas of non-edematous shifted white matter fibers. By contrast, trace apparent diffusion coefficient (ADC) values in those areas were found to be similar to contralateral side and normal control values. Analysis of the three diffusion tensor eigenvalues revealed that the increase in the fractional anisotropy is a result of two processes. The first is the increase in the diffusion parallel to the fibers-λ 1 (by 18%), and the second is the decrease in the diffusion perpendicular to fibers-λ 3 (by 34%) as compared with the contralateral side. These opposing changes cause an increase in the diffusion anisotropy but no change in the trace ADC. It is suggested that the pressure caused by the tumor may lead to an increase in white matter fiber tension, thus causing an increase in λ 1. On the other hand, the same pressure causes increased fiber density per unit area, leading to a higher degree of restricted diffusion in the extracellular space and, hence, a reduction in λ 3 .
UNCTIONAL MR imaging has become a routine tool for presurgical functional brain mapping. With fMR... more UNCTIONAL MR imaging has become a routine tool for presurgical functional brain mapping. With fMR imaging, functionality assessment is based on changes in BOLD corresponding to presented stimuli or task demands. 7,23 The primary objective of fMR imaging in neurosurgery is to reduce the need for invasive functional mapping techniques, such as the preoperative Wada test and intraoperative electrophysiological stimulation mapping. 13,22 Data from several studies have shown that, at least for language and motor functions, there is a fairly good regional correlation between intraoperative physiological mapping and fMR imaging findings. A question that remains to be answered is what is the relationship between detected fMR imaging signals at a certain location and the effective functionality of that region. "Effective functional-ity" refers to the critical role of a region to an evoked behavior. The invasive methods of brain mapping determine criticality by inhibiting or exciting activation in a region and by examining the resultant behavior. In contrast, fMR imaging demonstrates an activated network of regions involved in a specific task and precludes conclusions on criticality. Signals obtained during fMR imaging have been shown to correlate closely with field potentials that are generated by input activation of the neuronal population within a region. They do not, however, reflect the traveling of potentials within neuronal fibers or between regions. Therefore, fMR imaging can be considered as a functional mapping technique applied to minimize damage to functionally relevant gray matter in the vicinity of lesions. Brain surgery often requires intervention within white matter structures that could interfere with vital connectivity. Hence, comprehensive presurgical functional brain mapping should integrate information about neuronal activation corresponding to fiber tract organization and integrity in the vicinity of the candidate region for operation.
Toxic optic neuropathy is a complex, multifactorial disease potentially affecting individuals of ... more Toxic optic neuropathy is a complex, multifactorial disease potentially affecting individuals of all ages, races, places, and economic strata. Etiology includes nutritional, environmental, toxicologic, and genetic factors. Most cases of nutritional amblyopia are encountered in disadvantaged countries. However, toxic amblyopia related to drug treatment or alcohol abuse is also encountered in the Western world. Typically, toxic and nutritional optic neuropathy is progressive, with bilateral symmetrical painless visual loss causing central or cecocentral scotoma. There is no specific treatment for this disorder. Nevertheless, early detection and prompt management may ameliorate and even prevent severe visual deficit.
To compare the effect of peribulbar and sub-Tenon's anesthesia on intraocular pressure (I... more To compare the effect of peribulbar and sub-Tenon's anesthesia on intraocular pressure (IOP) and ocular pulse amplitude (OPA) in the injected eye and the fellow noninjected (control) eye. Tel Aviv Medical Center, Tel Aviv, Israel. This prospective study measured IOP and OPA at baseline and 1 and 10 minutes after administration of lidocaine anesthesia in 40 consecutive adult patients having elective cataract surgery. The IOP remained stable throughout the study with both modes of anesthesia. One minute after injection of the anesthetic agent, the OPA was significantly decreased in the injected eyes in both the sub-Tenon's (24%; P < .05) and peribulbar (25%; P < .05) groups. The decrease in the OPA in the sub-Tenon's group (14%; P < .05) was detectable after 10 minutes in the control eyes. In the peribulbar anesthesia group, the OPA in the control eyes increased significantly (9%; P < .05) 1 minute after injection of the anesthetic agent, returning to preinjection levels 10 minutes after the injection. The OPA in the eyes in which lidocaine was injected decreased significantly in both the sub-Tenon's and peribulbar groups. These findings have implications for the management of patients whose ocular circulation may be compromised.
Cette invention concerne des procedes et des methodes permettant d'introduire des sondes ther... more Cette invention concerne des procedes et des methodes permettant d'introduire des sondes therapeutiques chez un patient. Des modes de realisation de cette invention comprennent un systeme d'introduction de sonde automatise et un guide d'introduction de sonde comprenant un manchon de guidage de sonde mobile; un element servant a positionner ledit manchon de guidage de sonde; et une unite de commande pouvant fonctionner pour recevoir une definition d'un site dans le corps d'un patient et pour commander le positionnement et l'orientation dudit manchon de facon qu'une sonde introduite a travers ledit manchon progresse en direction du site en question. Cette invention concerne egalement des applications de cryochirurgie.
Cette invention concerne des dispositifs et des methodes permettant de planifier et de superviser... more Cette invention concerne des dispositifs et des methodes permettant de planifier et de superviser une chirurgie mini-invasive. Cette invention apporte des ameliorations a des systemes de planification, de surveillance et de commande de cryochirurgie.
PURPOSE. To investigate the role of endogenously generated nitric oxide (NO) in the relaxation of... more PURPOSE. To investigate the role of endogenously generated nitric oxide (NO) in the relaxation of bovine iris sphincter. METHODS. Isolated bovine sphincters were mounted on an isometric tension apparatus. Contraction-relaxation response was elicited by electrical field stimulation (ES; 12 Hz, 50-msec duration, 70 -80 V). Relaxation was arbitrarily defined as maximal decrease of tension below prestimulation baseline after cessation of ES. We also determined the tissue levels of cyclic guanosine monophosphate (cGMP) by radioimmunoassay. RESULTS. ES produced a biphasic response: contraction followed by relaxation. After cessation of ES, the muscle relaxed to below the initial baseline tension. Tetrodotoxin (TTX) abolished most of the contraction and all the relaxation response. Atropine blocked most of the contraction component, leaving the relaxation component unchanged. Prazosin and bupranolol (␣ 1 -adrenergic and -adrenergic antagonists, respectively) also did not affect the relaxa...
Investigative Ophthalmology Amp Visual Science, Mar 1, 2000
PURPOSE. To investigate the role of endogenously generated nitric oxide (NO) in the relaxation of... more PURPOSE. To investigate the role of endogenously generated nitric oxide (NO) in the relaxation of bovine iris sphincter. METHODS. Isolated bovine sphincters were mounted on an isometric tension apparatus. Contraction-relaxation response was elicited by electrical field stimulation (ES; 12 Hz, 50-msec duration, 70-80 V). Relaxation was arbitrarily defined as maximal decrease of tension below prestimulation baseline after cessation of ES. We also determined the tissue levels of cyclic guanosine monophosphate (cGMP) by radioimmunoassay. RESULTS. ES produced a biphasic response: contraction followed by relaxation. After cessation of ES, the muscle relaxed to below the initial baseline tension. Tetrodotoxin (TTX) abolished most of the contraction and all the relaxation response. Atropine blocked most of the contraction component, leaving the relaxation component unchanged. Prazosin and bupranolol (␣ 1-adrenergic and -adrenergic antagonists, respectively) also did not affect the relaxation component of the response. Neither substance P nor its antagonist (N-acetyl-L-tryptophane 3,5-bis (trifluoromethyl)-benzyl ester; ATTB) inhibited or mimicked the response. The nitric oxide synthase (NOS) inhibitors N-nitro-Larginine methyl ester (L-NAME), N-nitro-L-arginine (L-NNA), and aminoguanidine dose-dependently inhibited the relaxation response by 50% to 70%. The free radical scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (carboxy-PTIO) and the guanylyl cyclase inhibitor methylene blue also abrogated 70% and 45% of the relaxation response, respectively. ES caused an increase in muscle cGMP from 2.3 Ϯ 0.3 to 3.9 Ϯ 0.5 picomoles per muscle. L-NNA or L-NAME significantly decreased the tissue cGMP content (to 1.2 Ϯ 0.1 picomoles per muscle) and prevented the increase caused by ES. CONCLUSIONS. The relaxation component of the iris sphincter response to ES is a distinct nonadrenergic, noncholinergic, ES-induced event. Most of the relaxation is mediated by the endogenously generated NO-guanylyl cyclase-cGMP cascade.
Diffusion Tensor Imaging (DTI) is used to characterize the diffusion properties of deviated white... more Diffusion Tensor Imaging (DTI) is used to characterize the diffusion properties of deviated white matter caused by brain tumors. DTI was recently shown to be very helpful in delineating white matter both within brain lesions and surrounding them. Displacement of white matter fibers may be one of the consequences of tumor growth adjacent to white matter. The combination of white matter mapping with DTI and gray matter mapping using functional MRI, in some cases, facilitated assessment of the relation between the shifted cortical areas and the corresponding white matter tracts. We found that the fractional anisotropy extracted from DTI is increased by 38% in areas of non-edematous shifted white matter fibers. By contrast, trace apparent diffusion coefficient (ADC) values in those areas were found to be similar to contralateral side and normal control values. Analysis of the three diffusion tensor eigenvalues revealed that the increase in the fractional anisotropy is a result of two processes. The first is the increase in the diffusion parallel to the fibers-λ 1 (by 18%), and the second is the decrease in the diffusion perpendicular to fibers-λ 3 (by 34%) as compared with the contralateral side. These opposing changes cause an increase in the diffusion anisotropy but no change in the trace ADC. It is suggested that the pressure caused by the tumor may lead to an increase in white matter fiber tension, thus causing an increase in λ 1. On the other hand, the same pressure causes increased fiber density per unit area, leading to a higher degree of restricted diffusion in the extracellular space and, hence, a reduction in λ 3 .
Diffusion Tensor Imaging (DTI) is used to characterize the diffusion properties of deviated white... more Diffusion Tensor Imaging (DTI) is used to characterize the diffusion properties of deviated white matter caused by brain tumors. DTI was recently shown to be very helpful in delineating white matter both within brain lesions and surrounding them. Displacement of white matter fibers may be one of the consequences of tumor growth adjacent to white matter. The combination of white matter mapping with DTI and gray matter mapping using functional MRI, in some cases, facilitated assessment of the relation between the shifted cortical areas and the corresponding white matter tracts. We found that the fractional anisotropy extracted from DTI is increased by 38% in areas of non-edematous shifted white matter fibers. By contrast, trace apparent diffusion coefficient (ADC) values in those areas were found to be similar to contralateral side and normal control values. Analysis of the three diffusion tensor eigenvalues revealed that the increase in the fractional anisotropy is a result of two processes. The first is the increase in the diffusion parallel to the fibers-λ 1 (by 18%), and the second is the decrease in the diffusion perpendicular to fibers-λ 3 (by 34%) as compared with the contralateral side. These opposing changes cause an increase in the diffusion anisotropy but no change in the trace ADC. It is suggested that the pressure caused by the tumor may lead to an increase in white matter fiber tension, thus causing an increase in λ 1. On the other hand, the same pressure causes increased fiber density per unit area, leading to a higher degree of restricted diffusion in the extracellular space and, hence, a reduction in λ 3 .
UNCTIONAL MR imaging has become a routine tool for presurgical functional brain mapping. With fMR... more UNCTIONAL MR imaging has become a routine tool for presurgical functional brain mapping. With fMR imaging, functionality assessment is based on changes in BOLD corresponding to presented stimuli or task demands. 7,23 The primary objective of fMR imaging in neurosurgery is to reduce the need for invasive functional mapping techniques, such as the preoperative Wada test and intraoperative electrophysiological stimulation mapping. 13,22 Data from several studies have shown that, at least for language and motor functions, there is a fairly good regional correlation between intraoperative physiological mapping and fMR imaging findings. A question that remains to be answered is what is the relationship between detected fMR imaging signals at a certain location and the effective functionality of that region. "Effective functional-ity" refers to the critical role of a region to an evoked behavior. The invasive methods of brain mapping determine criticality by inhibiting or exciting activation in a region and by examining the resultant behavior. In contrast, fMR imaging demonstrates an activated network of regions involved in a specific task and precludes conclusions on criticality. Signals obtained during fMR imaging have been shown to correlate closely with field potentials that are generated by input activation of the neuronal population within a region. They do not, however, reflect the traveling of potentials within neuronal fibers or between regions. Therefore, fMR imaging can be considered as a functional mapping technique applied to minimize damage to functionally relevant gray matter in the vicinity of lesions. Brain surgery often requires intervention within white matter structures that could interfere with vital connectivity. Hence, comprehensive presurgical functional brain mapping should integrate information about neuronal activation corresponding to fiber tract organization and integrity in the vicinity of the candidate region for operation.
Toxic optic neuropathy is a complex, multifactorial disease potentially affecting individuals of ... more Toxic optic neuropathy is a complex, multifactorial disease potentially affecting individuals of all ages, races, places, and economic strata. Etiology includes nutritional, environmental, toxicologic, and genetic factors. Most cases of nutritional amblyopia are encountered in disadvantaged countries. However, toxic amblyopia related to drug treatment or alcohol abuse is also encountered in the Western world. Typically, toxic and nutritional optic neuropathy is progressive, with bilateral symmetrical painless visual loss causing central or cecocentral scotoma. There is no specific treatment for this disorder. Nevertheless, early detection and prompt management may ameliorate and even prevent severe visual deficit.
To compare the effect of peribulbar and sub-Tenon's anesthesia on intraocular pressure (I... more To compare the effect of peribulbar and sub-Tenon's anesthesia on intraocular pressure (IOP) and ocular pulse amplitude (OPA) in the injected eye and the fellow noninjected (control) eye. Tel Aviv Medical Center, Tel Aviv, Israel. This prospective study measured IOP and OPA at baseline and 1 and 10 minutes after administration of lidocaine anesthesia in 40 consecutive adult patients having elective cataract surgery. The IOP remained stable throughout the study with both modes of anesthesia. One minute after injection of the anesthetic agent, the OPA was significantly decreased in the injected eyes in both the sub-Tenon's (24%; P < .05) and peribulbar (25%; P < .05) groups. The decrease in the OPA in the sub-Tenon's group (14%; P < .05) was detectable after 10 minutes in the control eyes. In the peribulbar anesthesia group, the OPA in the control eyes increased significantly (9%; P < .05) 1 minute after injection of the anesthetic agent, returning to preinjection levels 10 minutes after the injection. The OPA in the eyes in which lidocaine was injected decreased significantly in both the sub-Tenon's and peribulbar groups. These findings have implications for the management of patients whose ocular circulation may be compromised.
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