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Biomedical subjects

M Lahav

Publications and source records attributed to M Lahav.

At least 127 records · Page 7Linked to original sources
PubMed1982

Circulating prostacyclin and thromboxane levels in patients with diabetic retinopathy.

Prostacyclin (PGI2) is the most potent endogenous inhibitor of platelet aggregation yet discovered. Thromboxane (TXA2) promotes aggregation and degranulation of platelets. It is hypothesized that an homeostasis exists between these pathways that is protective against vascular damage and is disturbed in several diseases such as diabetes. Circulating levels of PGI2-TXA2 in 35 patients with adult onset diabetes and 15 controls have been assayed. Twenty patients had background retinopathy, and 15 had proliferative retinopathy. Circulating levels of PGI were found to be elevated in 9/15 patients with proliferative diabetic retinopathy, 2/20 diabetic patients with background or no retinopathy, and 0/15 controls. PGI levels may correlate, therefore, with the severity of the retinopathy.

Diabetic Retinopathy↗
PubMed1982

Advanced pigmentary retinal degeneration: an ultrastructural study.

A case of advanced pigmentary retinal degeneration is described. Posterior subcapsular cataract and a remnant of the anterior hyaloid system on the posterior lens surface were found. Extensive dispersion of pigment and organization of the vitreous base were present. Gliosis was seen in the retina, and no photoreceptors were evident. The retinal blood vessel walls were extensively hyalinized, with cell debris and deposition of basement-membrane-like material, which may have originated from perivascular pigment-laden cells of pigment epithelial origin. The pigment epithelium showed extensive proliferation in clumps. Pigmented retinal pigment epithelium (RPE) cells without lipofuscin, migrating nonpigmented RPE cells, and macrophages with large lysosomal bodies could be identified in each clump. An abundance of extracellular basement-membrane-like material or mucopolysaccharide was seen in the retina and adjacent to the RPE. This material probably originated from the abnormal RPE. Abnormalities of the large and small choroidal vessels are present.

Choroid↗
PubMed1982

Versatile method for evaluating a cell culture by various morphological techniques.

Cellulose acetate is a versatile material for evaluating cells grown under identical conditions by various morphological techniques. This inexpensive material is transparent, easily cut to size and shape, nontoxic to cell cultures, and resistant to most chemicals used in histochemistry and in scanning and transmission electron microscopy. Samples may be obtained during and after the culture process. Cellulose acetate slides can be mounted directly over glass slides for direct observation and are easily peeled off plastic blocks for electron microscopy, leaving the cells behind. Relative disadvantages include its autofluorescence and a tendency to soften in strong acids or pure solutions of organic solvents such as xylene and propylene oxide.

Cells, Cultured↗
PubMed1982

Collagenolytic activity in keratoconus.

Corneal buttons were obtained from eight young adult patients with advanced keratoconus and were incubated in an organ culture system. The medium was assayed for collagenolytic activity using 14C-labeled reconstituted native collagen fibers as substrate. The assay was performed with and without prior collagenase activation with trypsin. The results indicated that the medium obtained from keratoconic corneas showed higher levels of collagenolytic activity compared with normal control corneas. We suggest that the level of collagenase activation may be a pathogenic factor in the development of keratoconus.

Adult↗
PubMed1981

Incidence of epibulbar tumors in lesotho.

A series of 18 epibulbar tumors are reported from Lesotho, a nontropical African country. The etiologic risk factors in epibulbar tumors are evaluated in termas of the environmental conditions present in Lesotho. The pathogenesis of epibulbar tumors is discussed in terms of histological progression from benign to malignant lesions following prolonged exposure to presumed etiologic risk factors.

Adult↗
PubMed1981

Eyelid tumors of sweat gland origin.

Tumors of sweat gland origin are not uncommon in the periocular region. These tumors frequently pose diagnostic difficulty due to the wide range of histopathological patterns, and to the fact that they may be infiltrative or have metastatic potential despite their relatively benign appearance. This report discusses the classification and diagnosis of five sweat gland tumors with variable histological appearance, including syringoma, mixed tumors, adenoma of ductal origin, and mucinous adenocarcinoma of sweat gland origin.

Adenocarcinoma, Mucinous↗
PubMed1981

Effect of prolactin and prostaglandins on the stimulation of prolactin binding sites in the male rat liver.

Induction of prolactin hepatic receptors in the male rat by exogenous prolactin and the possible involvement of prostaglandins in this process were studied. When ovine prolactin 500 microgram/kg was administered sc in saline containing 10% PVP (polyvinylpyrrolidone), twice daily for 6.5 days and the rats killed 48 h after the last injection, the specific binding of 125I-labelled ovine prolactin to prolactin hepatic receptors was raised 26-fold, while administration of prolactin in saline only caused a 7-fold increase. A well correlated log dose-response relationship was demonstrated between 12.5 and 500 microgram of prolactin in saline-PVP, with lowest dose causing an 18-fold increase in binding. A shorter 4.5 day treatment of prolactin in saline-PVP caused only a small 3-fold increase in prolactin binding. Scatchard analysis showed that these increases resulted from increases in receptor concentration. The effect of prolactin on the induction of the hepatic receptors could not be mimicked by PGE1, PGE2 or PGF2 alpha, nor could PGF2 alpha synergize with a short treatment with prolactin. Further, indomethacin caused no significant effect on this action of prolactin. It seems that prolactin does not induce its own receptors in the rat liver by stimulation of prostaglandins in this tissue.

Animals↗
PubMed1980

Bacteriolytic activity of human gingival exudate.

We investigated the bacteriolytic activity of gingival crevicular fluid (CF) on 14C-labeled Streptococcus faecalis, Streptococcus mutans, Staphylococcus aureus, and on whole dental plaque. CF was collected from 100 healthy donors pooled and centrifuged at 200 g. CF supernate and a frozen and thawed extract of the pellet were interacted with the different bacterial strains, while Streptococcus faecalis and Staphylococcus aureus released 60% and 75% of the radioactive label, only 38% of it was solubilized from Streptococcus mutans, following their incubation with the CF supernate. The findings agreed with results obtained by interacting bacteria with a frozen and thawed lysate of human peripheral blood leukocytes. On the other hand, extracts from frozen and thawed CF pellet were inactive. Further, lipoteichoic acid and lipopolysaccharide were released by CF from Gram-positive and Gram-negative bacteria, respectively. The role of bacteriolytic factors, present in CF, as a result of the interaction between microorganisms and leukocytes at inflammatory sites is discussed.

Actinomyces↗
PubMed1980

Enterotoxigenic Escherichia coli (ETEC) isolated in the Tel-Aviv (Israel) area.

The prevalence of enterotoxigenic E coli (ETEC) as a pathogenic agent of diarrhoea in the Tel-Aviv (Israel) area was determined, and the isolated E. coli strains characterized. During three periods (summer 1977, summer 1978, and summer 1979), a total of 335 specimens were tested for the presence of E. coli producing LT and ST toxin. Most of the specimens were from sporadic ambulatory diarrhoea cases (children and adults) attending a number of health care clinics in Tel-Aviv. Two to five colonies were tested from each sample. ETEC was detected in 69 cases (20%): LT/ST strains were isolated from 9 cases (2.7%); LT from 7 cases (2.1%); and ST from 53 cases (15.2%). ETEC was isolated in all age groups. In 19 specimens, 2 or more of 4 colonies tested were enterotoxigenic and were identical according to biotype, antibiotic sensitivity, and serogroup. These findings suggest that enterotoxigenic strains predominated in the bacterial population of the stool specimen. Part of the isolated ETEC strains belonged to serotypes already known as enterotoxigenic in different geographic areas of the world. The most frequently encountered were serogroups O8 (9 cases) represented by at least three serotypes, among them O8:K40:H9, and serotype O6:K15:H16 (5 cases); a number of serotypes were represented only by two cases or by single cases. Among 16 LT-producing stains (LT/ST and LT-only), 13 belonged to 3 serogroups, while ST-only strains represented a large spectrum of serotypes, some of which are now known as enterotoxigenic. Several serotypes common in other geographical locations were not detected.

Adolescent↗
PubMed1980

Immunoglobulin E and A levels in atopic and anaphylactic children.

Seventy-six children between 18 months and 12 years of age were included in this study. Sixty-one were atopic and 15 had anaphylaxis due to bee stings or drugs. Immunoglobulins: A, G. M and E were determined and evaluated with respect to age and diagnosis. IgA levels were lower in atopic children between six and ten years than in normals. IgE levels were high in both atopic and anaphylactic patients but higher in the atopic than in the anaphylactic group. The results are discussed, focusing on the question of basic immunologic impairment in allergy.

Anaphylaxis↗
PubMed1980

Placental concentrations of progesterone, estradiol-17 beta, and cyclic AMP at delivery.

In contrast to most mammals, human parturition is not preceded by a rise in the estradiol : progesterone ratio in peripheral plasma. Thus tissue concentrations of progesterone, estradiol-17 beta, and cyclic adenosine monophosphate (AMP) were measured in placentas obtained after spontaneous vaginal delivery (SVD, N = 11), after oxytocin-induced labor (OXIL, N = 5), and at elective cesarean section (ECS, N = 8). Both progesterone and estradiol were higher in placentas obtained from SVD compared with those from ECS (progesterone: 2.95 +/- 0.26 versus 1.96 +/- 0.29 ng/mg tissue, P < .025; estradiol: 33.6 +/- 5.2 versus 26.4 +/- 3.8 pg/mg). Placentas from OXIL had intermediate progesterone (2.50 +/- 0.47 ng/mg) but the highest estradiol concentration (41.4 +/- 3.2 pg/mg). Cyclic AMP was 29.8 +/- 1.5, 39.6 +/- 8.0, and 35.9 +/- 3.9 pmoles/100 mg tissue in SVD, OXIL, and ECS placentas, respectively. Thus no rise in the placental estradiol : progesterone ratio was found in association with spontaneous labor.

Cesarean Section↗
PubMed1980

Significance of prostaglandins in the regulation of cyclic events in the ovary and uterus.

We examined the role of prostaglandins in three pivotal events of the female reproductive cycle: ovulation, luteolysis, and menstruation. Four general approaches were adopted, using in vivo and in vitro models: use of inhibitors of cyclooxygenase and of PG action; immunoneutralization of individual prostaglandins; administration of exogenous prostaglandins; and attempts to correlate PG levels in tissues and body fluids to physiologic events. It can be concluded that prostaglandins or related metabolites of arachidonic acid are essential in laboratory rodents for follicular rupture and the release of a fertilizable oocyte, but not for other LH actions on the follicle that are mimicked by PG or for the neuroendocrine triggering of ovulation. PGs control the cyclic regression of the corpus luteum and appear also to be implicated in the decidual reaction and in the menstrual shedding of the endometrium in primates. Some aspects of the control of follicular PG formation and of PG action were analyzed. Gonadotropins stimulate follicular PG synthesis by a steroid-independent cyclic nucleotide-mediated induction of cyclooxygenase. Both the thecal and granulosa cell compartments show this response. An effect of the phytolectin conconalavin A on ovarian PG synthesis is described. The response of follicular cells to prostaglandin E2 exhibits the phenomenon of desensitization and is influenced by agents modifying the structure and function of cytoskeletal elements. Evidence is put forward for the view that abrogation by PGF2 alpha of the stimulatory action of LH on luteal adenylate cyclase is the biochemical basis of the luteolytic action of this prostaglandin. While the precise mechanism of PG action on the endometrium remains to be defined, PG-synthetase inhibitors have already found useful applications in the management of menstrual disorders, such as functional dysmenorrhea and menorrhagia. The role in ovarian and uterine physiology of the more recently discovered labile arachidonate metabolites, such as the endoperoxides, prostacyclin, and thromboxanes, has not yet been adequately explored.

Animals↗