Suppression of testicular androgenesis by D-tryptophan-6-luteinizing hormone-releasing hormone does not affect TSH secretion in male subjects

Basal and TRH-stimulated TSH secretion was evaluated in six patients suffering from prostatic cancer, before and after antiandrogenic treatment performed using a long-acting LHRH analogue, D-Trp-6-LHRH. Although serum testosterone values dropped to minimal levels after treatment, TSH secretion remained unchanged. Observed results suggest that pharmacological castration does not affect the regulatory mechanisms involved in the control of TSH secretion.     

Brain-capillary architecture of the newt,Triturus cristatus carnifex (Caudata: Salamandridae): Scanning electron-microscopical study of vascular corrosion casts

The brain-microvascular architecture of the newt (Triturus cristatus carnifex) was studied by scanning electron-microscopical examination of microvascular corrosion casts. It is characterized at the leptomeningeal level by a superficial network of single vessels that leave the meningeal sheath to form hairpin-shaped capillary loops. These loops penetrate the nervous parenchyma to varying depths and are variously bent, inclined, and twisted. Each hairpin-like loop consists of descending and ascending limbs connected by a distal U-shaped segment. The limbs are of equal diameter and lack physical differentiation. Some loops branch in a secondary loop, but there are no intraparenchymal connections with analogous surrounding structures. On vascular casts we observed detailed imprints of endothelial cell nuclei. This microvascular architecture is present in the whole brain except in leptomeninx and choroidal plexuses. The vascular pattern of T. cristatus carnifex resembles that of apodans. However, it differs from the anuran condition, which is characterized by a three-dimensional parenchymal network and from that of Ambystoma mexicanum which displays an intermediate condition between a single-capillary network and a capillary-loop model. At the level of paired capillaries, a counter-current exchange system may occur between the two limbs of the same loop, an arrangement that could promote uniformity of extracellular fluid composition in parenchyma.     

Impermeability of newt cerebral and pial capillaries to exogenous peroxidase. A light and electron microscope study

The permeability of cerebral vessels to exogenous peroxidase was studied in the newt. The reaction product was found only inside the cerebral or pial blood vessels. Electron microscope investigations revealed the presence of reaction product along the luminal area of vessels and in some parts of the intercellular spaces at the level of tight junctions joining endothelial cells. On the basis of the ultrastructural peroxidase localization, the presence of a brain-blood barrier in Triturus is discussed.     

Sustained impairment of pituitary and testicular function in prostatic cancer patients treated with a depot form of a GnRH agonist

Seven patients suffering from prostatic cancer were treated with a slow-release D-Trp-6-LHRH preparation for a period of 24-32 months. LH, FSH, PRL and testosterone levels were evaluated before and at the end of treatment and then 40 days later. Baseline and GnRH-, TRH-, and HCG-stimulated hormonal values decreased after treatment. The possibility that a long-term treatment with GnRH analogues induces a sustained suppression of pituitary and testicular function is suggested.     

Near-infrared spiroximetry: noninvasive measurements of venous saturation in piglets and human subjects.

We present a noninvasive method to measure the venous oxygen saturation (Sv(O(2))) in tissues using near-infrared spectroscopy (NIRS). This method is based on the respiration-induced oscillations of the near-infrared absorption in tissues, and we call it spiroximetry (the prefix spiro means respiration). We have tested this method in three piglets (hind leg) and in eight human subjects (vastus medialis and vastus lateralis muscles). In the piglet study, we compared our NIRS measurements of the Sv(O(2)) (Sv(O(2))-NIRS(resp)) with the Sv(O(2)) of blood samples. Sv(O(2))-NIRS(resp) and Sv(O(2)) of blood samples agreed well over the whole range of Sv(O(2)) considered (20-95%). The two measurements showed an average difference of 1.0% and a standard deviation of the difference of 5.8%. In the human study, we found a good agreement between Sv(O(2))-NIRS(resp) and the Sv(O(2)) values measured with the NIRS venous occlusion method. Finally, in a preliminary test involving muscle exercise, Sv(O(2))-NIRS(resp) showed an expected postexercise decrease from the initial baseline value and a subsequent recovery to baseline.