Biomedical subjects
Publications and source records attributed to M Lahav.
In a group of 25 selected children with asthma associated with repeated, severe respiratory tract infection, a high incidence of IgA deficiency and elevated IgE levels were found. This may be of importance in the evaluation of such patients.
Many molecules which are achiral can crystallize in chiral (enantiomorphic) crystals and, under suitable conditions, crystals of only one chirality may be obtained. The formation of right- or left-handed crystals in excess is equally probable. Lattice-controlled (topochemical) photochemical or thermal solid-state reactions may then afford stable, optically active products. In the presence of the chiral products, achiral reactants may preferentially produce crystals of one chirality, leading to a feedback mechanism for the generation and amplification of optical activity. Amplification of optical activity can also be achieved by solid-state reactions. The optical synthesis of biologically relevant compounds by such routes may be envisaged.
The effect of photodynamic inactivation on experimental herpes simplex keratitis in rabbits was investigated using neutral red as a photosensitizing dye followed by exposure to light at 425nm. Combined dye application and light exposure early in the disease (two days following infection) reduced to a minimal extent the severity and duration of the acute epithelial infection. The effect on well-established keratitis (three days postinfection) was negligible as evaluated by clinical grading, viral recovery, and histopathological study. In initial experiments, it was found that the dye and light did not have any observable deleterious effect on intact corneas or cause any noticeable delay in healing of injured cornias. Further, when light or dye were utilized alone, neither changed the severity or duration of the keratitis. In vitro treatment of the virus with light and dye destroys its ability to produce experimental keratitis.
Two patients are described in whom black hypopyon and black keratic precipitates occurred as a result of intraocular melanoma. In one instance the hypopyon was due to a clinically unsuspected primary choroidal melanoma in an eye with opaque media; in the second case the tumor was metastatic to the uvea froma cutaneous melanoma. Histological examination showed the hypopyon to be composed of pigment-laden macrophages and neoplastic melanoma cells.
Histopathologic examination of six, adult human eyes revealed "rosette-like" structures in the retina which appear to have developed after maturation of the retina. These structures resemble dysplastic rosettes which are generally interpreted as a sign of maldevelopment of the retina (retinal dysplasia). The underlying lesions in the eyes of these patients were ocular ischemia, sickle-cell retinopathy, diabetic retinopathy, central retinal vein occlusion, and trauma. It is suggested that a distinction should be made between these degenerative-regressive changes and dysplastic rosettes which represent an abortive attempt of regeneration by germinal cells.
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The lysis of 14C-labeled bacteria by hydrolases of human and rabbit leukocytes was studied in vitro. While Staphylococcus albus, Streptococcus faecalis, and Streptococcus mutans were highly susceptible to lysis, Staphylococcus auresus was intermediate in its susecptibility to lysis by the leukocyte enzymes. Group A Streptococcus, Listeria monocytogenes, Shigella flexneri, Escherichia coli, and Mycobacterium smegmatis were very resistant to degradation by these enzymes. The lytic activity of leukocyte lysates from human and rabbit blood was probably due to acid hydrolases of polymorphonuclear leukocytes. Extracts of human blood monocytes and of rabbit peritoneal and lung macrophages were less lytic for the bacteria tested. Lymphocytes and platelet extracts were not bacteriolytic. The lytic effect of the leukocyte lysates was not inhibited by KCN or sodium azide, but was abolished to a large extent by cationic polyelectrolytes such as protamine sulfate, histone and leukocyte cationic proteins, and poly-lysine, as well as by the anionic polyelectrolytes such as heparin, chondroitin sulfate, DNA, carrageenin, alginate sulfate, dextran sulfate, and ploy-L-glutamic acid. Other potent inhibitors of bacteriolysis were trypan blue, congo red, phosphatidic acid, normal immunoglobulins, and components of streptococcal cell wall.
The clinical picture resembling fundus albipunctatus was seen to develop in rabbits following subcutaneous injection with dibutyl oxalate. On histologic examination, the flecks were found to be due to intracellular accumulation of calcium oxalate in the RPE cells. The clinical and histologic features of this animal model closely resemble the recently described entity of oxalate retinopathy in humans which was seen in the presence of high circulating oxalate levels. It is suggested that the presence of metabolic disorders or toxicity which are known to cause oxalate depositions should be sought in patients with fundus albipunctatus.
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