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Biomedical subjects

Y Katz

Publications and source records attributed to Y Katz.

At least 127 records · Page 7Linked to original sources
PubMed1988

Increase in central and peripheral benzodiazepine receptors following surgery.

[3H]Flunitrazepam, [3H]PK 11195, [3H]quinuclidinyl benzilate (QNB) and monoamine oxidase (MAO) A and B activity were measured in male rats 1, 3 and 7 days following laparotomy. The surgery resulted in the up-regulation of central benzodiazepine (BZ) receptors in cerebral cortex and of peripheral BZ binding sites in brain and kidney on the first and third days after operation. This increase was followed by a decrease to normal range 7 days after the surgical procedure. [3H]QNB binding to muscarinic receptors in the cerebral cortex as well as MAO A and B activity in rat cerebral cortex and kidney were not affected by the surgical manipulation. The modulatory effect of surgery on BZ receptors corresponds to stages of the healing process in surgical wounds.

Animals↗
PubMed1988

Synthesis and regulation of complement protein factor H in human skin fibroblasts.

The alternative pathway of C activation is Ag-independent and forms a first line of defense against infection before immune response. The C3 convertase, C3bBb, formed during activation of the alternative pathway is tightly regulated, with destabilization produced by factor H. Using metabolic labeling with [35S]methionine, immunoprecipitation, and SDS-PAGE, we demonstrated that human skin fibroblasts synthesized and secreted factor H protein. Two forms of the protein were identified, the approximately 160-kDa form seen more prominently in serum and a 45-kDa form that has also been identified in serum. The cells contained two forms of factor H mRNA, 4.4 and 1.8 kb. IFN-gamma increased factor H protein synthesis and mRNA content. No effect was observed with LPS. Neither HepG2 cells or human peripheral blood monocytes synthesized factor H protein or contained factor H mRNA.

Cell Line↗
PubMed1988

On the use of regular solution theory as a theoretical frame for the analysis of membrane phenomena.

The structural heterogeneity of the phospholipid membrane causes difficulties in the analysis of membrane functions. These difficulties can be overcome by using probes which dissolve preferentially into one of the regions, provided that a general theory correlating probe behaviour to membrane structure exists. The use of regular solution theory (RST) as a theoretical frame for membrane analysis is examined below, and it is concluded that some, but not all, of the relations furnished by the theory are useful for membrane analysis. Using these relations, it is concluded that the hydrophobic region of the membrane has a stabilizing effect. The polar region is less stable and changes faster than the hydrophobic region. Diffusion rates are smaller in the hydrophobic region.

Diffusion↗
PubMed1988

Synergism between gamma interferon and lipopolysaccharide for synthesis of factor B, but not C2, in human fibroblasts.

Four different human fibroblast cell lines synthesized C2 and factor B. Factor B synthesis was increased 12.1-fold by 50 ng/ml LPS and 7.1-fold by 100 U/ml IFN-gamma. C2 synthesis was increased only 2.1-fold by LPS, but 6.4-fold by IFN-gamma. Both LPS and IFN-gamma increased levels of factor B mRNA. LPS induced a 4.7-fold greater increase in factor B protein than in factor B mRNA, whereas IFN-gamma stimulated comparable increases in protein and mRNA. These data suggest that LPS acts to increase factor B synthesis at both pretranslational and translational sites, while IFN-gamma acts primarily at a pretranslational level. In contrast to factor B, increases in C2 protein and C2 mRNA were comparable for both stimuli. A synergistic effect between the two stimuli was observed for factor B only: protein synthesis was increased 54.5-fold or 2.8-fold greater than the additive effects of the stimuli separately. The rate of synthesis in the presence of LPS and IFN-gamma together could not be achieved by increasing concentrations of, or the times of incubation with, either stimulus separately. The synergism was not the result of an increased sensitivity of the cells to either stimulus and was not reproduced by preincubation with one stimulus before incubation with the other stimulus. Several lines of evidence suggest that the synergism, like the stimulation of factor B synthesis by LPS, was dependent on both translational and pretranslational regulation of factor B mRNA. C2 and factor B synthesized in human fibroblasts may play a role in host defense in inflammatory reactions before increases in vascular permeability and recruitment of other complement producing cells.

Cells, Cultured↗
PubMed1988

Synovial fibroblast-like cells synthesize seven proteins of the complement system.

Fibroblast-like cells from synovial tissue obtained during arthroscopy in 4 young adults with recent knee trauma were biosynthetically labeled with 35S-methionine, and protein production was quantitated by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Synovial fibroblast-like cells synthesized C1r, C1s, C1 inhibitor, C2, C3, factor B, and factor H, all with the same sizes and subunit structures as the proteins synthesized in skin fibroblasts. The capacity to synthesize these proteins was not lost with passages or freeze-thawing. Gamma-interferon stimulation increased synthesis of all 7 proteins. Lipopolysaccharide increased synthesis of only C3 and factor B. Unlike in whole rheumatoid tissue, C4 and C5 were not detected. Synovial lining cells may be an important source of local complement for participation in local defense or development of pathologic states.

Cell Adhesion↗
PubMed1988

The effects of haloperidol on the partial reinforcement extinction effect (PREE): implications for neuroleptic drug action on reinforcement and nonreinforcement.

The effects of haloperidol 0.1 mg/kg on the partial reinforcement extinction effect (PREE) paradigm at one trial a day, were examined. Two groups of rats were trained to run in a straight alley. The continuously reinforced (CRF) group received food reward on every trial. The partially reinforced (PRF) group was rewarded on a quasi-random 50% schedule. All animals were then tested in extinction. Haloperidol 0.1 mg/kg was administered in a 2 x 2 design, i.e., drug-no drug in acquisition and drug-no drug in extinction. The PREE, i.e., increased resistance to extinction of partially reinforced as compared to continuously reinforced animals, was obtained in all four drug conditions. The administration of haloperidol in acquisition increased markedly resistance to extinction in CRF animals. The administration of the drug in extinction decreased resistance to extinction in both CRF and PRF animals. The results are explained in terms of two independent actions of haloperidol: the well-known effect of reduction in the effectiveness of reinforcement as well as enhancement of the effectiveness of nonreinforcement.

Animals↗
PubMed1987

Facilitation of the expression but not the acquisition of latent inhibition by haloperidol in rats.

In the latent inhibition (LI) paradigm, nonreinforced preexposure to a stimulus retards subsequent conditioning to that stimulus. The administration of haloperidol in both the preexposure and the conditioning stages was found to enhance LI in the conditioned emotional response (CER) procedure (Weiner and Feldon, 1986). The present experiments investigated the effects of 0.1 mg/kg haloperidol administration on LI in a two-way avoidance procedure, consisting of two stages: preexposure, in which the to-be-conditioned stimulus, tone, was repeatedly presented without reinforcement; and conditioning, in which the animals acquired a two-way avoidance response with the tone serving as the warning signal. Experiments 1 and 2 tested whether the administration of haloperidol confirmed to the preexposure stage, where learning to ignore the nonreinforced stimulus takes place, would suffice to enhance the LI effect. In Experiment 1, preexposure and conditioning were conducted 24 hr apart. LI was obtained in both the placebo and haloperidol conditions, but the effect was not more pronounced under the drug. In addition, haloperidol-treated animals exhibited impaired avoidance performance. In Experiment 2, preexposure and conditioning were given 72 hr apart. With this interval, haloperidol did not affect avoidance performance. However, also under these conditions, the magnitude of the LI effect was not larger in the haloperidol-treated groups, indicating that the administration of the drug in the preexposure stage alone did not suffice to enhance LI.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Lack of effect of 28 days of neuroleptic treatment on platelet benzodiazepine binding sites in schizophrenics.

Twenty-eight days of neuroleptic treatment of 11 schizophrenics aged 16-23 years did not affect the binding values of 3H-PK 11195 to platelets. This lack of effect was in contrast to reduced peripheral benzodiazepine binding sites (PBS) observed in platelets of schizophrenics medicated over 2 years. These results may indicate that neuroleptic-induced down-regulation of PBS is a time-dependent phenomenon.

Adolescent↗
PubMed1987

Familial occurrence of typhoid acute glomerulonephritis.

Three cases of typhoid nephritis occurring in a single family are reported. A clinical similarity to poststreptococcal nephritis was noted, although no hypocomplementemia was observed. The same phage type occurred in other patients who did not exhibit nephritis. The possibility of a host factor was therefore considered to be involved, although no HLA haploid-type link was found in the patients. These cases illustrate that in certain geographical areas the possibility of typhoid fever should be considered in patients with nephritis and concomitant fever.

Acute Disease↗
PubMed1985

Intestinal obstruction due to Ascaris lumbricoides mimicking intussusception.

Two children were admitted for clinical and radiologic signs of small-bowel obstruction. Examination revealed an abdominal mass that was suspected of being a mass of intussusception. Bowel obstruction caused by Ascaris lumbricoides was found at surgery. The laboratory, radiologic, and surgical findings are presented with a short review of the literature with emphasis on diagnosis, incidence, complications, and treatment.

Ascariasis↗
PubMed1985

Flavor avoidance expressed in grooming by pine voles (Microtus pinetorum): importance of context and hormonal factors.

Pine voles (Microtus pinetorum) were given sipper tubes containing saccharin solution, and after drinking, were injected with 0.15 M LiCl. Subsequently, two-sipper tests were given to assure the presence of conditioned flavor avoidance (CFA), and then animals were presented with saccharin in carboxymethyl-cellulose on their own fur (autogrooming), or on the fur of cagemates (allogrooming). CFA was expressed in two-sipper tests, and during allogrooming of material from a cagemate's fur, but not during autogrooming. Failure to express CFA during autogrooming was associated with high circulating levels of corticosterone and cortisol, steroids implicated in behavioral arousal. These results are consistent with previous work showing that rats and mice will ingest flavors while grooming that they would otherwise avoid. We speculate that our findings provide a plausible explanation for the successful use of grooming to increase the ingestion of unpalatable toxicants.

Adrenal Cortex Hormones↗
PubMed1984

Plasma steroids in the ammocoete of Petromyzon marinus.

Radioimmunoassays revealed the presence of the following steroids (or immunoreactive steroid fractions) in the plasma of larval sea lampreys: progesterone, corticosterone, cortisol, androstenedione, testosterone, dihydrotestosterone, estrone, and estradiol. Several types of stress served to provoke the release of these substances. A statistically significant effect of the treatment was noted under only one condition: squeezing of the body of decapitated ammocoetes during blood collection caused an increase in plasma dihydrotestosterone and a decrease in plasma estradiol. The discovery of all eight steroids (or immunoreactivities) assayed for suggests that the plasma of the ammocoete may contain a considerable number of additional steroids yet to be identified.

Androstenedione↗