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Biomedical subjects

M Lahav

Publications and source records attributed to M Lahav.

At least 163 records · Page 9Linked to original sources
PubMed1977

Effect of leukocyte hydrolases on bacteria. IX. The release of lipoteichoic acid from group A streptococci and from Strep. mutans by leukocyte extracts and by lysozyme: relation to tissue damage in inflammatory sites.

Human leukocyte extracts, egg white lysozyme, cationic proteins, polymyxin, colimycin, and phenol are capable of releasing lipoteichoic acids (LTA) from group A streptococci and Strep. mutans. While the extraction of LTA by phenol is optimal at pH 4.7, the release of LTA from streptococci by the other agents is optimal at pH 7.4. LTA released by all agents was found to have the same sensitizing abilities, as determined by passive hemagglutination, and to have a similar chemical composition, as shown by thin-layer chromatography and radioactive scanning. The LTA-releasing capacity of all the agents is strongly inhibited by normal human serum. The possible role played by LTA released by leukocyte factors in the pathogenesis of tissue damage during bacterial infections is discussed.

Cell Extracts↗
PubMed1977

Effect of leukocyte hydrolases on bacteria. X. The role played by leukocyte factors, cationic polyelectrolytes, and by membrane-damaging agents in the lysis of Staphylococcus aureus: relation to chronic inflammatory processes.

A heat-stable factor present in extracts of human blood leukocytes is capable of lysing young Staphylococcus aureus at pH 5.0. Lysis is characterized by breakdown of cell-wall components as judged by electron microscopic and biochemical analysis. The leukocyte extracts can be replaced by a variety of agents known to injure cell membranes, e.g., leukocyte cationic protein histone, polymyxin B, colimycin, phospholipase A, and lysolecithin. The mechanisms by which all these agents bring about the degradation of the staphylococcal walls was studied. By using 14C-labeled cell walls devoid of cytoplasmic structures, it was demonstrated that none of the above-mentioned agents had a direct lytic effect on purified cell walls. On the other hand, when any of these agents first interacted with intact staphylococci, a factor (presumably an autolysin) was generated that directly lysed the cell walls. Lysis of cell walls in the presence of intact staphylococci used as a source of autolysin was strongly inhibited by a variety of anionic polyelectrolytes such as heparine and liquoid. The possible role played by bacterial autolysins in the generation of microbial cell-wall components capable of triggering chronic inflammation is discussed.

Bacteriolysis↗
PubMed1977

Suppression of 20 alpha-hydroxysteroid dehydrogenase activity in cultured rat luteal cells by prolactin.

20alpha-Hydroxysteroid dehydrogenase (20 alpha-SDH) activity increases in the cycling corpus luteum of the rat, beginning at 14.00 h on the day of diestrus, but remains low in corpora lutea of pregnancy throughout the first 19 days of gestation. When cells derived from 7-day-old corpora lutea of pregnant rats were cultured for 7 or 12 days, there was a spontaneous rise in 20 alpha-SDH activity from an initial value of 0.44 +/- 0.27 to 4.1 +/- 0.7 units/mg supernatant protein. Addition of LH (NIH-S-18; 2.0 mug/ml) or prostaglandin F2alpha (2.8 X 10(-5) M) to the medium from day 4 to the end of incubation period caused a slight but significant reduction in 20 alpha-SDH activity (20%, P less than 0.05). Supplementation of the medium with ovine prolactin (HIH-P-S11; 10.0 mug/ml) from the time of seeding or from the 2nd to 4th day of culture reduced the activity of 20 alpha-SDH measured on day 12 by 61% (P less than 0.001). This finding suggests that the suppression of 20 alpha-SDH by prolactin, hitherto demonstrated only in vivo results from a direct action of the hormone on the luteal cell.

Animals↗
PubMed1977

Effect of phosphonoacetic acid in the treatment of experimental herpes simplex keratitis.

In the rabbit 5% phosphonoacetic acid ointment suppressed herpetic keratitis as well as 0-5% idoxuridine ointment. After 5 days of treatment quantitative virus titres showed that phosphonoacetic acid was superior to idoxuridine in the inhibition of herpes virus replication. Phosphonoacetic acid was found to be nontoxic to the eye in both clinical and histopathological studies. Recent reports suggest that the mechanism of action of phosphonoacetic acid appears to be the blocking of the virus DNA polymerase, which is essential for the synthesis of herpes virus DNA.

Animals↗
PubMed1977

beta-Adrenergic receptors in rat kidney: direct localization by a fluorescent beta-blocker.

A new fluorescent beta-adrenergic blocker, 9-amino-acridin propranolol (9-AAP), was administered intravenously to albino rats. Fluorescent aggregates of 9-AAP binding sites were concentrated in the vascular poles of the glomeruli in association with the preglomerular afferent arterioles. 9-AAP fluorescence was reduced following pretreatment with (+/-)- and (-)-propranolol and was less affected in rats pretreated by the (+)-racemic isomer. 9-AAP binding sites were also observed on the lining epithelium of the renal collecting system. Our data suggest that 9-AAP may label beta-adrenergic receptors in rat kidney.

Adrenergic beta-Antagonists↗
PubMed1977

Retinal neoplasia and dysplasia. I. Induction by feline leukemia virus.

Feline leukemia virus, a naturally occurring C-type virus (oncorna virus), was injected systemically and intraocularly into fetal and newborn kittens. A light microscopy study of the resultant ocular tumor changes was carried out. One animal developed an intraocular tumor of apparent retinal origin. Eight animals showed intraocular neoplastic cell infiltration. The most common ocular change observed was retinal dysplasia. Sequential histologic examination of enucleated eyes showed diffuse intraocular inflammation after viral inoculation. In the developing retinas progressive disorganization and necrosis were documented, with subsequent reorganization into cell clumps and dysplastic rosette structures. The retinal pigment epithelium showed proliferation and intraretinal migration. The mature retina exhibited full-thickness folds and tubes associated with infoldings of the retinal pigment epithelium.

Animals↗
PubMed1976

Beta-adrenergic receptors in rat myocardium: direct detection by a new fluorescent beta-blocker.

A new fluorescent beta-blocker, 9-amino-acridin propranolol (9-AAP), was administered i.v. to rats. Multiple fluorescent 9-AAP binding sites were observed on cardiac muscle cells in frozen sections. Intensity and density of cardiac 9-AAP fluorescence were markedly reduced following pretreatment with (+/-)- and (-)-propranolol but not with (+)-propranolol. Our findings suggest that 9-AAP may label beta-adrenergic receptor sites in rat myocardium.

Acridines↗
PubMed1976

The interaction of leukocytes and their hydrolases with bacteria in vitro and in vivo: the modification of the bactericidal and bacteriolytic reactions by cationic and anionic macromolecular substances and by anti-inflammatory agents.

Acid hydrolases from extracts of human blood leucocytes lyse Staph.aureus, Staph.albus and Strep.faecalis in vitro. The leucocyte enzymes can be substituted by a lytic mixture which contains crude trypsin, lysolecithin, phospholipase C and lysozyme, which lyse other bacterial species, e.g. E.coli and Listeria which are resistant to leucocyte enzymes. Bacteriolysis by the lytic agents is strongly inhibited by the anionic polyelectrolytes, heparin, chondroitin sulphate, DNA, dextran sulphate and other sulphated mucopolysaccharides, by the cationic materials, histone, protamine sulphate, leucocyte cationic proteins and polylysine. Other strong inhibitors are trypsan blue and congo red, the phospholipids phosphatidyl serine and ethanolamine, gold thiomalate, extracts of coffee and tea and the anti-inflammatory agents, ultracorten-H, and ultracortenol. Bacteriolysis is also strongly inhibited by normal human serum and by synovial fluids from patients with a variety of joint diseases. The inhibitors in these body fluids are associated with the globulin fractions. Since mixtures of anionic and cationic polyelectrolytes, at equimolar concentrations, failed to inhibit bacteriolysis by leucocyte enzymes, it is postulated that a delicate balance between positively and negatively charged inhibitors control the degradation of cell wall components of bacteria in inflamed areas. Such bacterial components, induce 'storage type' granulomas. The possible role played by polyelectrolytes in the control of the inflammatory process induced by leucocyte hydrolases will be discussed.

Animals↗
PubMed1976

Trachoma in a rural Haitian community.

We selected 43 patients, aged 15 days to 57 yesrs, for intensive study after screening 975 people for clinical evidence of trachoma in rural Haiti. Trachoma was present in Haiti with low endemicity and was followed by relatively mild sequelae. Laboratory studies confirmed the disease through demonstration of conjunctival inclusion bodies by immunofluoresence and serotyping of antibody in sera or eye secretions, or both. Of 23 patients (age 1 to 36 years) with active trachoma, all had serum antibody to chlamydia (range 1:10 to 1:640), nine had eye secretion antibody (range 1:10 to 1:1280), and one was inclusion positive. The remaining 20 patients (age 15 days to 57 years) had the following diagnosis: atypical follicles (eight), conjunctivitis with or without mucopurulent discharge (ten) innactive pannus only (one), and severe anemia (one). Only 16 of the 20 were tested for serum antibody and all were positive (1:10 to 1:5,120), 11 of 20 had eye secretion antibody (1:10 to less than or equal to 1:640), and one was inclusion positive. Serotyping attempted on 22 patients yielded 16 patients with antibodies specific for type A, one patient with type B, and five who were not typed.

Adolescent↗
PubMed1976

Traumatic rupture of healed cataract wounds.

Three patients suffered blunt trauma that caused rupture of the site of cataract incision three to 12 years after surgery. Epithelial cells were noted in the old cataract would of a 79-year-old white man. The second patient, a 25-year-old black women, had bilateral ocular toxoplasmosis and loss of vitreous humor at the time of lens extraction. The third patient, a 63-year-old white woman, had open-angle glaucoma treated previously with filtering procedures and cyclocryotherapy. The ultimate outcome was poor in each case.

Adult↗
PubMed1976

Malignant teratoid medulloepithelioma in a dog.

A malignant teratoid medulloepithelioma that arose from the ciliary body was found in an adult Beagle. The anterior part contained relatively well-differentiated tumor cells, cartilage, and ganglion cells. These structures were interpreted as teratoid formations derived from the embryonic anlage of the medullary epithelium. The more posterior part was highly anaplastic and invasive. A transitional area contained neural rosettes of the Flexner-Wintersteiner type. This tumor is rare in both man and animals.

Animals↗
PubMed1976

Canine herpes-induced retinal dysplasia and associated ocular anomalies.

Thirty-eight newborn Beagle puppies from eight litters of a specific pathogen-free colony maintained in isolation were inoculated with canine herpesvirus. Pups were killed between one and 30 days after inoculation. Histopathologic studies were carried out on the eyes and other tissues in conjunction with fluorescent antibody and viral isolation studies. Evidence of ocular inflammation manifested by panuveitis with the presence of intranuclear inclusion bodies was usually seen by the fourth day after infection. Eyes with severe inflammation showed peripheral anterior synechiae, cataract, and keratitis. The presence of the virus was confirmed by viral isolation from ocular tissues and fluorescent antibody studies. Developmental anomalies included retinal dysplasia with fold and tube formation of the neural retina, retardation of retinal maturation, and areas of necrosis and reorganization were seen. The retinal pigment epithelium showed initially patchy depigmentation and vacuolization and, subsequently, folding hypertrophy and duplication as well as areas of widespread atrophy and patchy loss. In some animals ectopic retina was found within cystic spaces of the optic nerve. These experiments confirm the ability of canine herpes infection in neonatal pups to produce severe ocular inflammation with subsequent retinal dysplasia and associated ocular anomalies.

Animals↗
PubMed1976

Successful therapy of herpes hominis keratitis in rabbits by 5-iodo-5'-amino-2'5'-dideoxyuridine (AIU): a novel analog of thymidine.

The efficiency of 5-iodo-5'-amino-2'5'-dideoxyuridine (AIU) in the therapy of experimental herpes keratitis in rabbits has been examined. Virus infections were established bilaterally in 40 animals using herpes simplex, type 1 (NIH strain 11124). Twenty-four hours after infection the rabbits were divided into five matched groups of eight and each group was treated, double-blind, with topical drugs at four-hour intervals for a total of 72 hours. The solutions instilled were: (1) saline; (2) IdUrd, 1 mg. per milliliter; (3) AIU, 1 mg. per milliliter; (4) AIU, 4 mg. per milliter; and (5) AIU, 8 mg. per milliliter. Each eye was examined daily for 12 days and graded independently by two ophthalmologists. Although IdUrd and AIU (8 mg. per milliliter) were effective therapeutically, IdUrd had a greater effect. The AIU at 1 and 4 mg. per milliliter were less active, but showed more rapid healing than the saline control. Viral recovery studies are consistent with the clinical observations. A second independent experiment, similar to that described above, gave essentially identical results. Although less potent than IdUrd, AIU does provide effective therapy for herpes keratitis.

Administration, Topical↗