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Biomedical subjects

B Bloch

Publications and source records attributed to B Bloch.

301 records · Page 17Linked to original sources
PubMedDate not supplied

Immunocytochemical localization of dopamine D1 receptors in the retina of mammals.

Dopamine is one of the major neurotransmitters in the retina. It is released from amacrine and interplexiform cells into both inner (IPL) and outer (OPL) plexiform layers. Several dopaminergic actions are known to occur through D1 receptors (D1R) but the precise location of these receptors has not been established. An antibody that recognizes the intracytoplasmic C-terminal of the rat D1R was used to detect D1R, immunohistochemically, in rats (Wistar and RCS), mouse, hamster, and macaque monkey retinas. The OPL was heavily stained in each species, consistent with the known actions of dopamine on horizontal cells. Three to five bands were observed in the IPL, depending on species. Three were in the a sublayer, the outermost of which was close to the amacrine cell layer, and may represent the massive dopamine input to the AII rod-amacrine cells. As observed in mice, where bipolar cells are D1-immunoreactive, the band located in sublayer 3 of the IPL may contain cone-bipolar cell terminals. A band of D1R-immunoreactivity in the b sublayer of the IPL contains ON-bipolar cell terminals and a second site of interaction between dopaminergic cells and the AII amacrine cells. This sublayer was absent from the RCS rat retina, suggesting a severe impairment of the rod-driven pathway following rod degeneration in these mutant rats. Cells in the ganglion cell layer exhibited relatively heavy staining, and may be ganglion cells or displaced amacrine cells. Some extrasynaptic localizations of D1R in the retina are suggested.

Animals↗
PubMedDate not supplied

Immunohistochemical detection of growth hormone-releasing factor in brain.

The concept of a hypothalamic neurohumoral control for anterior pituitary secretion postulates the existence of a growth hormone-releasing factor (GRF) of neuronal origin that stimulates the pituitary gland to release growth hormone (GH). Such a compound has not yet been isolated and characterized from the brain, although there is extensive physiological and biochemical evidence for its existence (reviewed in ref. 2). However, a 44-amino-acid amidated peptide having the physiological properties of GRF as well as chemical similarities was recently isolated from a human pancreatic tumour that had caused acromegaly. Two shorter biologically active fragments of 40 and 37 residues were also isolated. The synthetic replicates of these human pancreas GRF (hpGRF) peptides specifically stimulate GH release in vitro and in vivo. Assuming similarity or identity between the putative hypothalamic GRF and the tumour-derived hpGRF, we have used immunohistochemistry to search for hpGRF-like immunoreactivity in the brain. We report here that antisera against the hpGRF1-40 peptide specifically stain neuronal cell bodies in the arcuate nucleus of the primate hypothalamus, with fibres projecting to the median eminence and ending in contact with portal vessels. This topography is characteristic of a neuronal system elaborating a releasing factor. These results provide evidence that hypothalamic GRF is very similar, if not identical, to hpGRF.

Aged↗
PubMedDate not supplied

Specific depletion of immunoreactive growth hormone-releasing factor by monosodium glutamate in rat median eminence.

A potent and specific growth hormone-releasing factor (GRF) was recently isolated and characterized from a human islet cell tumour of the pancreas that caused acromegaly. Antibodies raised against the synthetic replicate of this peptide have allowed the immunohistochemical identification of GRF-producing neurones within the primate central nervous system. Such neurones are found mainly in the arcuate nucleus in human and monkey hypothalamus, suggesting that this nucleus is a primary source of GRF. We have further investigated this hypothesis by studying the anatomical organization of GRF neurones in rat hypothalamus, using an antibody raised against the recently characterized rat hypothalamic GRF in normal animals and in animals neonatally treated with monosodium glutamate (MSG), a treatment which results in the selective destruction of arcuate nucleus neurones. We present here the results which show that GRF-producing neurones are located mainly in the arcuate nucleus of rats. MSG treatment results in the complete loss of GRF-immunoreactive cell bodies within this nucleus and provokes a selective disappearance of GRF-immunoreactive fibres in the median eminence. These results show that the arcuate nucleus is the origin of the GRF-containing fibres that project to the median eminence and establish the MSG-treated rat as an in vivo model for studying growth hormone secretion in the absence of neurohumoral GRF.

Animals↗
PubMedDate not supplied

Ondansetron compared with granisetron in the prophylaxis of cisplatin-induced acute emesis: a multicentre double-blind, randomised, parallel-group study. The Ondansetron and Granisetron Emesis Study Group.

This is the first international, multi-centre, double-blind, randomised, parallel group study to directly compare the efficacy and safety profile of a single intravenous dose of ondansetron (8 or 32 mg) with granisetron (3 mg) in the control of cisplatin-induced acute emesis. A total of 496 patients were randomised to receive one of three anti-emetic treatments prior to cisplatin chemotherapy (> or = 50 mg/m2). Of these, 165 and 162 patients received 8 and 32 mg of ondansetron, respectively, and 169 patients received 3 mg of granisetron. Complete control of emesis (0 emetic episodes) over 24 h was reported in 59% of patients in the 8-mg ondansetron group, 51% of patients in the 32-mg ondansetron group and 56% of patients in the granisetron group. Complete or major control (< or = 2 emetic episodes) was achieved in 76 and 74% of patients in the 8- and 32-mg ondansetron group, respectively, compared with 78% of patients in the granisetron group. Nausea graded none or mild 24 h after the start of cisplatin infusion was reported in 71 and 69% of patients in the 8- and 32-mg ondansetron groups, respectively, and in 73% of patients in the granisetron group. There were no significant differences between the treatment groups when global satisfaction scores were compared. Logistic regression models were fitted to assess any interaction between treatments and prognostic factors (age, gender, alcohol use, cisplatin dose or concomitant chemotherapy) on complete or major response, but there was no evidence of interaction for any factor. All three anti-emetic treatments were well tolerated and no severe or unexpected drug-related adverse events were observed with ondansetron or granisetron. Headache, the most reported drug-related adverse event for all three treatment groups, occurred in 9% of all patients. In summary, no significant difference was observed between any of the treatment groups with respect to emesis, nausea or drug-related adverse events.

Adult↗
PubMedDate not supplied

The International Organization for Standardization technical committee on implants for surgery.

The author defines surgical implants. Surgical applications of implants are shown to be increasing and the range of materials used is growing. Surgeons' knowledge of materials science is generally inadequate and there is now a need for implant standards and for assurance of their quality control. The problems in achieving this internationally are discussed. The achievements of the ISO's technical committee (TC150) on implants for surgery are described.

Biocompatible Materials↗