Introduction: Thyroid autoregulation has been related to intraglandular content of an unknown put... more Introduction: Thyroid autoregulation has been related to intraglandular content of an unknown putative iodocompound. The thyroid is capable of producing different iodolipids such as 6-iodo-deltalactone (IL␦) and 2-iodohexadecanal (2-IHDA). Data from different laboratories have shown that these iodolipids inhibit several thyroid parameters. IL␦ has an antigoitrogenic action but no data about the action of 2-IHDA on this parameter has been published. Objectives: to study the action of 2-IHDA on methimazole (MMI)-induced goiter and analyze if this compound can cause the involution of preformed goiter. Results: Administration of MMI to rats during 10 days increased thyroid weight by 112%. This effect was significantly inhibited by the simultaneous injection of 20 g/day of 2-IHDA (51% vs. MMI) while iodine or non iodinated hexadecanal were without action. Thyroidal proliferating cell nuclear antigen (PCNA) content was increased by MMI while 2-IHDA decreased this value (control: 100%; MMI: 190 ± 11; MMI + 2-IHDA: 134 ± 10). Serum TSH was increased after MMI administration and 2-IHDA did not modify this parameter (control: 1.89 ± 0.10; MMI: 8.19 ± 0.93 ng/ml; MMI + 2-IHDA: 7.38 ± 0.72). Treatment with MMI increased thyroidal cAMP content (control: 16.1 ± 0.82, MMI: 42.4 ± 4.6 fmol/mg protein) while injection of 2-IHDA significantly decreased this value (22.3 ± 2.0). Goiter prevention by 2-IHDA was also observed at 30 days of treatment reducing total number of cells (51% inhibition) and epithelial height (81% inhibition). Goiter involution was induced after withdrawal of MMI and injection with 2-IHDA, KI or saline. 2-IHDA led to a reduction of 74.5% in thyroid weight after 3 days while spontaneous involution (saline) was only of 32%. KI failed to alter this value. This significant involution was accompanied by a reduction in the number of cells (66%). Administration of the iodolipids did not produce significant changes in several serum parameters such as total T 3 and T 4 , cholesterol, transaminases, urea and creatinine. Conclusion: 2-Iodohexadecanal, as 6-iodo-deltalactone, prevents goiter growth in rats and opens a potential therapeutic application of iodolipids.
Viviparous liolaemids that inhabit cool and harsh environments of Patagonia and the highlands of... more Viviparous liolaemids that inhabit cool and harsh environments of Patagonia and the highlands of the Andes exhibit distinctive life-history traits to synchronize births with benign environmental conditions. We studied the reproduction of Phymaturus cf. palluma, a viviparous species that inhabits rocky outcrops in cool environments of the Andean highlands of San Juan, Argentina, and discuss our results in relation to the conservation status of this poorly known species. We determined male and female reproductive cycles, male testosterone cycle, allometry of morphometric variables and sexual size dimorphism, minimum adult size, clutch size, and mean annual reproductive output. Females of Phymaturus cf. palluma exhibited a biennial reproductive cycle, with a litter size of one to two offspring, resulting in a low mean annual reproductive output of 0.75 offspring/female/year. The male spermatogenic cycle was asynchronous among individuals. We observed males with sperm in the epididymis and high values of serum testosterone concentrations throughout the activity season. The sexual dimorphism and allometric analyses revealed that legs are wider in males than in females throughout the life span, and not linked to sexual maturity. In contrast, the head size in males and the trunk size in females are developed after sexual maturity, suggesting that they have arisen through sexual selection. Our study confirmed a pattern of prolonged female reproductive cycles and low mean annual reproductive output in the genus Phymaturus, resulting in this species having one of the lowest values of mean annual reproductive output for lizards in the world.
The results of these experiments demonstrate that histones from brain inhibit the replication of ... more The results of these experiments demonstrate that histones from brain inhibit the replication of DNA in vitro. A similar effect is observed with polylysine or polyarginine. The reversion of inhibition by polyglutamic acid or acidic proteins is completed in all cases except when the DNA is previously complexed with histones, polyarginine or polylysine. This suggest that histones masking of DNA towards the polymerases involves electrostatic forces.
Las disfunciones tiroideas son frecuentes en mujeres en edad reproductiva y son una causa común d... more Las disfunciones tiroideas son frecuentes en mujeres en edad reproductiva y son una causa común de infertilidad, fertilidad subnormal, abortos espontáneos, problemas en el embarazo y parto prematuro. Se asocian con anovulación y ciclos menstruales anormales. La presencia de anticuerpos antitiroideos aumenta el riesgo de aborto, infertilidad y síndrome de ovario poliquístico (SOP). Las hormonas tiroideas (HT) pueden afectar la fertilidad indirectamente, interfiriendo con el eje hipotálamo-hipófiso-gonadal, o a nivel ovárico, ya que sus receptores (TR) están presentes en la mayoría de los tipos celulares ováricos. Las HT afectan la esteroideogénesis e inhiben la aromatasa, pero estimulan el crecimiento folicular. El hipotiroidismo produce hiperprolactinemia, que induce irregularidades en el ciclo, y en la rata, pseudopreñez, hipofunción del eje GH-IGF y aumento de la aromatasa y estradiol circulante. El hipertiroidismo produce un aumento temprano en la secreción preovulatoria de FSH, ...
Introduction: Thyroid autoregulation has been related to intraglandular content of an unknown put... more Introduction: Thyroid autoregulation has been related to intraglandular content of an unknown putative iodocompound. The thyroid is capable of producing different iodolipids such as 6-iodo-deltalactone (IL␦) and 2-iodohexadecanal (2-IHDA). Data from different laboratories have shown that these iodolipids inhibit several thyroid parameters. IL␦ has an antigoitrogenic action but no data about the action of 2-IHDA on this parameter has been published. Objectives: to study the action of 2-IHDA on methimazole (MMI)-induced goiter and analyze if this compound can cause the involution of preformed goiter. Results: Administration of MMI to rats during 10 days increased thyroid weight by 112%. This effect was significantly inhibited by the simultaneous injection of 20 g/day of 2-IHDA (51% vs. MMI) while iodine or non iodinated hexadecanal were without action. Thyroidal proliferating cell nuclear antigen (PCNA) content was increased by MMI while 2-IHDA decreased this value (control: 100%; MMI: 190 ± 11; MMI + 2-IHDA: 134 ± 10). Serum TSH was increased after MMI administration and 2-IHDA did not modify this parameter (control: 1.89 ± 0.10; MMI: 8.19 ± 0.93 ng/ml; MMI + 2-IHDA: 7.38 ± 0.72). Treatment with MMI increased thyroidal cAMP content (control: 16.1 ± 0.82, MMI: 42.4 ± 4.6 fmol/mg protein) while injection of 2-IHDA significantly decreased this value (22.3 ± 2.0). Goiter prevention by 2-IHDA was also observed at 30 days of treatment reducing total number of cells (51% inhibition) and epithelial height (81% inhibition). Goiter involution was induced after withdrawal of MMI and injection with 2-IHDA, KI or saline. 2-IHDA led to a reduction of 74.5% in thyroid weight after 3 days while spontaneous involution (saline) was only of 32%. KI failed to alter this value. This significant involution was accompanied by a reduction in the number of cells (66%). Administration of the iodolipids did not produce significant changes in several serum parameters such as total T 3 and T 4 , cholesterol, transaminases, urea and creatinine. Conclusion: 2-Iodohexadecanal, as 6-iodo-deltalactone, prevents goiter growth in rats and opens a potential therapeutic application of iodolipids.
Viviparous liolaemids that inhabit cool and harsh environments of Patagonia and the highlands of... more Viviparous liolaemids that inhabit cool and harsh environments of Patagonia and the highlands of the Andes exhibit distinctive life-history traits to synchronize births with benign environmental conditions. We studied the reproduction of Phymaturus cf. palluma, a viviparous species that inhabits rocky outcrops in cool environments of the Andean highlands of San Juan, Argentina, and discuss our results in relation to the conservation status of this poorly known species. We determined male and female reproductive cycles, male testosterone cycle, allometry of morphometric variables and sexual size dimorphism, minimum adult size, clutch size, and mean annual reproductive output. Females of Phymaturus cf. palluma exhibited a biennial reproductive cycle, with a litter size of one to two offspring, resulting in a low mean annual reproductive output of 0.75 offspring/female/year. The male spermatogenic cycle was asynchronous among individuals. We observed males with sperm in the epididymis and high values of serum testosterone concentrations throughout the activity season. The sexual dimorphism and allometric analyses revealed that legs are wider in males than in females throughout the life span, and not linked to sexual maturity. In contrast, the head size in males and the trunk size in females are developed after sexual maturity, suggesting that they have arisen through sexual selection. Our study confirmed a pattern of prolonged female reproductive cycles and low mean annual reproductive output in the genus Phymaturus, resulting in this species having one of the lowest values of mean annual reproductive output for lizards in the world.
The results of these experiments demonstrate that histones from brain inhibit the replication of ... more The results of these experiments demonstrate that histones from brain inhibit the replication of DNA in vitro. A similar effect is observed with polylysine or polyarginine. The reversion of inhibition by polyglutamic acid or acidic proteins is completed in all cases except when the DNA is previously complexed with histones, polyarginine or polylysine. This suggest that histones masking of DNA towards the polymerases involves electrostatic forces.
Las disfunciones tiroideas son frecuentes en mujeres en edad reproductiva y son una causa común d... more Las disfunciones tiroideas son frecuentes en mujeres en edad reproductiva y son una causa común de infertilidad, fertilidad subnormal, abortos espontáneos, problemas en el embarazo y parto prematuro. Se asocian con anovulación y ciclos menstruales anormales. La presencia de anticuerpos antitiroideos aumenta el riesgo de aborto, infertilidad y síndrome de ovario poliquístico (SOP). Las hormonas tiroideas (HT) pueden afectar la fertilidad indirectamente, interfiriendo con el eje hipotálamo-hipófiso-gonadal, o a nivel ovárico, ya que sus receptores (TR) están presentes en la mayoría de los tipos celulares ováricos. Las HT afectan la esteroideogénesis e inhiben la aromatasa, pero estimulan el crecimiento folicular. El hipotiroidismo produce hiperprolactinemia, que induce irregularidades en el ciclo, y en la rata, pseudopreñez, hipofunción del eje GH-IGF y aumento de la aromatasa y estradiol circulante. El hipertiroidismo produce un aumento temprano en la secreción preovulatoria de FSH, ...
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