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Biomedical subjects

N Katz

Publications and source records attributed to N Katz.

At least 91 records · Page 5Linked to original sources
PubMed1996

[Coronary risk factors in chronic hemodialysis patients].

BACKGROUND: In contrast to persons with normal renal function, coronary risk factors or indicators until yet could not clearly be defined in renal insufficiency. PATIENTS AND METHODS: 30 patients under chronic hemodialysis therapy were investigated; 15 patients with severe coronary artery disease and 15 patients with normal coronary angiogram were compared. Numerous factors of the manner of living (diet, smoking behaviour etc.) were registered and glucose and lipid metabolism, hemostatic and fibrinolytic system as well as blood pressure level were investigated. RESULTS: Besides higher HDL-cholesterol and tissue plasminogen activator (TPA) levels in patients without coronary heart disease, no significant difference could be found between both groups. The higher HDL levels were mainly due to the higher percentage of women in the coronary healthy group. There was no evidence of insulin resistance as a major pathogenic factor in the group with coronary heart disease. The blood pressure levels were not significantly different in both groups. CONCLUSION: Our quantitative examination of accepted or suspected coronary risk factors revealed no entity which turned out to be a reliable risk indicator for practical purposes.

Aged↗
PubMed1996

Microinjection of ADP-ribosylated actin inhibits actin synthesis in hepatocyte-hepatoma hybrid cells.

Treatment of hepatocyte-hepatoma hybrid cells with Clostridium botulinum C2 toxin led to a 167% increase in monomeric globular actin (G-actin) and to a 57% decrease in filamentous actin (F-actin) within 2 h. Simultaneously, the level of actin mRNA was specifically decreased to 49% and actin synthesis was significantly diminished. In contrast, treatment of hybrid cells with phalloidin led to a decrease in G-actin to 55% and to a reciprocal increase in actin mRNA to 244% and an increase in actin synthesis. These alterations of actin synthesis depending on the G-actin/F-actin ratio corresponded to the autoregulation of actin synthesis observed in primary cultures of rat hepatocytes. Microinjection of C2 toxin or of phalloidin into hepatocyte-hepatoma hybrid cells had the same effects on actin synthesis as incubation with either toxin in the culture medium. Microinjection of nonpolymerizable ADP-ribosylated G-actin into hepatocyte-hepatoma hybrid cells specifically decreased the incorporation of [35S]methionine into newly synthesized actin within 1 h. This decrease continued for at least 19 h. Microinjection of ADP-ribosylated actin led to rounding of cells and obvious disaggregation of actin filaments, which might be due to capping of actin filaments by the ADP-ribosylated actin. Because stabilization of actin filaments by phalloidin before microinjection of ADP-ribosylated actin also resulted in decreased actin synthesis, the concentration of monomeric G-actin seems to be responsible for the regulation of actin synthesis in hepatocyte-hepatoma hybrid cells, which can be regarded as immortalized hepatocytes.

Actins↗
PubMed1996

Cytogenetic study of radiation burden in thyroid disease patients treated with external irradiation or radioiodine.

Where clinically permitted, either external irradiation or radioiodine therapy is usually recommended for the treatment of differentiated thyroid cancer patients. The choice depends on the treatment philosophy of the responsible physician. This paper describes an attempt to clarify the radiation burden on the lymphocytes in consequence of these two therapeutic modalities. An analysis was made of the extent to which exposure to local neck irradiation (25 x 2 Gy) or radioiodine therapy (1734-2600 MBq) causes chromosomal aberrations in the lymphocytes of thyroid disease patients after total or subtotal thyroidectomy. External irradiation caused many more chromosomal aberrations than 131I therapy did, but analysis of the distribution of the aberrations suggested a homogeneous dose distribution only in 131I-treated and thyroidectomized cancer patients. In thyrotoxic patients with intact thyroid glands, the lower therapy doses (185-595 MBq) caused a significantly higher frequency of aberrations than that observed in thyroid cancer patients, and the dose distribution in the lymphocytes was inhomogeneous. Thus, in the modelling of accidental environmental radioiodine exposure, thyroid patients with small if any residual thyroids are not a suitable group.

Adult↗
PubMed1996

A Schistosoma mansoni fatty acid-binding protein, Sm14, is the potential basis of a dual-purpose anti-helminth vaccine.

Molecular cloning of components of protective antigenic preparations has suggested that related parasite fatty acid-binding proteins could form the basis of the protective immune crossreactivity between the parasitic trematode worms Fasciola hepatica and Schistosoma mansoni. Molecular models of the two parasite proteins showed that both molecules adopt the same basic three-dimensional structure, consisting of a barrel-shaped molecule formed by 10 antiparallel beta-pleated strands joined by short loops, and revealed the likely presence of crossreactive, discontinuous epitopes principally derived from amino acids in the C-terminal portions of the molecules. A recombinant form of the S. mansoni antigen, rSm14, protected outbred Swiss mice by up to 67% against challenge with S. mansoni cercariae in the absence of adjuvant and without provoking any observable autoimmune response. The same antigen also provided complete protection against challenge with F. hepatica metacercariae in the same animal model. The results suggest that it may be possible to produce a single vaccine that would be effective against at least two parasites, F. hepatica and S. mansoni, of veterinary and human importance, respectively.

Amino Acid Sequence↗
PubMed1996

The relationship between perineal cosmetic talc usage and ovarian talc particle burden.

OBJECTIVE: Epidemiologic studies support the hypothesis of a dose-related risk of epithelial ovarian cancer with perineal talc usage exposure. Frequency and duration of talc has not been previously correlated with ovarian talc content. STUDY DESIGN: Ovaries were studied from 24 women undergoing incidental oophorectomy who were interviewed regarding talc usage. Twelve subjects reported frequent perineal talc applications; the twelve controls reported no use. Ovarian tissue blocks were digested and analyzed by polarized light microscopy and analytic electron microscopy to identify and quantify talc. RESULTS: Talc was identified in all 24 cases by either light or electron microscopy. Talc particle counts were completely unrelated to reported levels of perineal talc exposure. CONCLUSIONS: The detection of talc in all ovaries demonstrates that it can reach the upper genital tract. Widespread exposure to talc during diapering may contribute to the ubiquitous presence of talc in ovarian tissue.

Adult↗
PubMed1996

Control of hepatic carbohydrate metabolism and haemodynamics in perfused rat liver by arterial and portal angiotensin II.

DESIGN: Angiotensin II (AII; 0.2, 5 and 25 nM) was infused during a single-pass perfusion of a rat liver via both the hepatic artery and the portal vein (portal or arterial AII). Infusion occurred both in the absence and in the presence of the AT1-receptor-antagonist losartan (1 and 10 microM). METABOLISM: Arterial and portal AII increased glucose output and shifted lactate uptake to release. Portal AII was 3 (0.2 nM) and 1.5 times (5 and 25 nM) more effective in increasing hepatic glucose release than similar levels of arterial AII. However, 0.2, 5 and 25 nM of arterially and portally applied AII had a similar level of efficiency in switching lactate uptake to release. The metabolic alterations by arterial and portal AII were, however, strongly inhibited by the addition of 1 microM losartan (an AT1-receptor-antagonist) and completely blocked by the presence of 10 microM losartan. HAEMODYNAMICS: Arterial and portal AII decreased the flow in the ipsilateral vessels to a similar extent, both demonstrating similar kinetics. Medium and high levels of arterial and portal AII caused pronounced flow alterations of the contralateral vessels. The AII-dependent reductions of arterial and portal flow were strongly inhibited by the presence of 1 microM losartan and were stopped by 10 microM of this blocker. RESULTS: The results demonstrate that arterial and portal AII caused alterations in the hepatic metabolism, demonstrating either clear (glucose balance) or no (lactate balance) differences, produced similar reductions of the ipsilateral flow, and pronounced and complex modulations of the contralateral flow.

Angiotensin II↗
PubMed1996

Pathogenetic factors of acute schistosomiasis mansoni: correlation of worm burden, IgE, blood eosinophilia and intensity of clinical manifestations.

A clinical study of 34 previously healthy young patients simultaneously infected in an endemic area of schistosomiasis mansoni is presented, emphasizing the initial phase of the infection. Its intensity was established according to the occurrence, intensity, and duration of the signs and symptoms in order to investigate the possible correlations between the worm burden (estimated by the number of eggs in faeces), the blood eosinophilia and specific levels of IgE (estimated by the area of immediate intradermal reaction), with the clinical manifestations. A significant but low-level association was found between the worm burden and morbidity, suggesting that multiple factors, besides worm burden itself, may contribute to the pathogenesis of the disease.

Acute Disease↗
PubMed1996

L-arginine prevents heart transplant arteriosclerosis by modulating the vascular cell proliferative response to insulin-like growth factor-I and interleukin-6.

BACKGROUND: L-arginine, a nitric oxide precursor, inhibits myointimal hyperplasia induced by balloon injury in native vessels. No studies are published on L-arginine effects on transplant arteriosclerosis. Insulin-like growth factor-I and interleukin-6 are mitogenic for smooth muscle cells and are involved in the cell-mediated and humoral immune response. METHODS: New Zealand White rabbits received cardiac allografts from Dutch Belted rabbits. All animals were fed a 0.5% cholesterol diet and received drinking water with (eight pairs) or without (eight pairs) L-arginine (2.5%) from day 7 to until they were killed at day 42. The recipients received cyclosporine A 10 mg/kg/day from transplantation until the time they were killed. RESULTS: Dietary L-arginine reduces myointimal hyperplasia in allograft coronary arteries from 44% +/- 4% in the non-L-arginine group to 16% +/- 2% (p < 0.002). The L-arginine significantly inhibits graft vascular cell proliferation induced by (1) insulin-like growth factor-I, from 328% +/- 66% to 154% +/- 28% (p < 0.05), (2) interleukin-6, from 376% +/- 97% to 138% +/- 30% (p < 0.05) and (3) the combination of insulin-like growth factor-I and interleukin-6 from 710% +/- 201% to 226% +/- 72% (p < 0.05). In recipient native aorta explants L-arginine also abolishes vascular cell proliferation stimulated by insulin-like growth factor-I and interleukin-6. The rejection grading is similar in the L-arginine (2.9 +/- 0.1) and control groups (2.7 +/- 0.1). Class II major histocompatibility antigen expression, T-lymphocyte, and macrophage infiltration in the cardiac allograft are unaffected by L-arginine. However, the diet significantly increased plasma nitric oxide from 15.4 +/- 2.3 to 45.1 +/- 11 mumol (p < 0.05). CONCLUSIONS: Dietary L-arginine attenuates transplant arteriosclerosis in vivo without affecting rejection. The protective effect seen in these experiments may relate to the generation of sufficient nitric oxide to prevent smooth muscle cell response to mitogens like insulin-like growth factor-I and interleukin-6.

Animals↗
PubMed1995

Gene polymorphism but not catalytic activity of angiotensin I-converting enzyme is associated with coronary artery disease and myocardial infarction in low-risk patients.

BACKGROUND: An insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme (ACE) gene has been postulated to be associated with an increased risk of coronary artery disease (CAD) and myocardial infarction (MI). METHODS AND RESULTS: In the present study, the effects of I/D gene polymorphism and of ACE activity on CAD and MI were investigated in 920 individuals who underwent coronary angiography for diagnostic purposes. In the total population and in all CAD and MI groups, a strong association was observed between the gene polymorphism and ACE activities; DD genotypes had approximately twofold higher ACE activities than II genotypes. Although classic risk and protective factors of CAD and MI were identified, associations of ACE genotype and of ACE activity to CAD and MI were not detected in the total population. Among subjects defined to be at lower risk of MI by low body mass index and low cigarette consumption, however, an association of the DD genotype with MI was found. Exclusion of individuals with triglyceride levels > 140 mg/dL and cholesterol levels > 180 mg/dL revealed an association of the DD genotype with CAD. An association of the ACE activity with CAD or MI could not be demonstrated in any of the low-risk populations. CONCLUSIONS: Increased ACE activity obviously is not a risk factor of CAD or MI. The importance of the deletion polymorphism for the development of CAD and MI may be restricted to individuals without classic risk factors.

Case-Control Studies↗
PubMed1995

Expression of the mRNA of heme-binding protein 23 is coordinated with that of heme oxygenase-1 by heme and heavy metals in primary rat hepatocytes and hepatoma cells.

A 23-kDa protein with high affinity for heme (KD = 55 nM), therefore termed heme-binding protein 23 kDa (HBP23), was purified from rat liver cytosol [Iwahara, S., et al. (1995) Biochemistry 34, 13398-13406]. Homology search of the cloned HBP23 cDNA revealed that this protein belongs to a recently recognized class of thiol peroxidases, the antioxidant peroxiredoxin family. Since HBP23 gene expression was highest in the liver, HBP23 mRNA regulation by heme and heavy metals was investigated in cultures of primary rat hepatocytes and mouse hepatoma Hepa 1-6 cells. In both cell cultures HBP23 mRNA levels were upregulated in a time- and dose-dependent manner by heme. Heme-dependent induction of HBP23 mRNA occurred coordinately with that of the heme-metabolizing enzyme heme oxygenase-1, which was recently identified as inducible by oxidative stress. Treatment of primary rat hepatocyte or hepatoma cell cultures with the heavy metals CdCl2 (10 microM) and CoCl2 (300 microM) induced in parallel HBP23 and HO-1 mRNA levels, in the case of CdCl2 to even higher levels than heme. By contrast, mRNA expression of another heme binding protein, hemopexin, was not induced in hepatocyte cell cultures by heme or heavy metals. The data suggest that the expression of HBP23 and HO-1 mRNA is regulated by (a) similar mechanism(s) in liver and that both genes could play a common physiological role as antioxidants and/or in heme metabolism.

Animals↗
PubMed1995

Modulation of hemopexin gene expression by physiological oxygen tensions in primary rat hepatocyte cultures.

Hyperoxia induces the expression of the hemopexin (Hx) gene in the liver in vivo. To investigate whether the Hx gene is activated by oxygen as such or via H2O2 as an oxygen signal transmitter the effects of arterial and venous O2 tensions as well as different concentrations of H2O2 on Hx mRNA expression were studied. After preculturing primary rat hepatocytes for 24 h at arterial O2 (16%) Hx mRNA was expressed with a maximal level (= 100%), when arterial O2 tension proceeded for 2 h, and to values of approximately 50%, when venous O2 tension (8%) proceeded for 2 h. When hepatocytes were precultured for 24 h under venous O2, Hx mRNA was induced by arterial O2 to values of 60% and under venous O2 to values of approximately 35%. The expression of beta-actin remained unchanged under arterial and venous O2. Exposure of hepatocyte cultures to H2O2 decreased the expression of Hx mRNA in a dose-dependent manner after 2 h, while heme oxygenase-1 (HO-1) mRNA was induced 2.5 fold. The results suggest that O2 per se rather than the reactive oxygen intermediate H2O2 modulates Hx expression.

Actins↗
PubMed1995

Autoregulation of actin synthesis in hepatocytes by transcriptional and posttranscriptional mechanisms.

Treatment of rat hepatocytes with the filamentous-actin-stabilizing toxin phalloidin decreased the amount of globular actin by 77% in the cytosol and by 80% in the nucleus within 12 h. Simultaneously, actin mRNA was specifically increased by 230%. The de-novo synthesis of actin mRNA, as measured by nuclear run-on transcription, was enhanced by 250%. Treatment of cells with actinomycin D blocked the increase of actin mRNA. The apparent half-life of actin mRNA was not significantly altered during treatment with phalloidin. In contrast, the globular-actin-stabilizing botulinum C2 toxin increased the amount of cytosolic globular actin by 50% within 12 h. Simultaneously, the actin mRNA level was decreased by 62%. However, de-novo synthesis of actin mRNA was not impaired. The apparent half-life of actin mRNA was decreased by approximately 60% during treatment with C2 toxin. The data strongly suggest an autoregulatory control of actin synthesis on the basis of the globular/filamentous actin ratio in rat hepatocytes at the transcriptional as well as at the posttranscriptional levels.

Actins↗
PubMed1995

Humoral immune responses in acute schistosomiasis mansoni: relation to morbidity.

An analysis of 25 individuals simultaneously exposed to cercariae of Schistosoma mansoni showed that morbidity (measured by the clinical/sonographic index) was more severe in patients with high-level egg output, irrespective of age or intensity of water contact. High levels of IgM and IgG antibodies to keyhole limpet hemocyanin and of IgA antibody to soluble egg antigen were documented predominantly during the acute phase of illness. Increased levels of these antibodies and of IgM antibody to soluble egg antigen correlated positively with morbidity after adjustment for age and intensity of water contact.

Acute Disease↗
PubMed1995

Autoregulation of actin synthesis by physiological alterations of the G-actin level in hepatocytes.

Hypotonic treatment of cultured rat hepatocytes significantly decreased the monomeric G-actin level by 18% after 120 min while the level of filamentous F-actin remained essentially unchanged. Simultaneously the level of cellular actin mRNA was increased by 53%. Incubation of hepatocytes for 120 min with the F-actin stabilizing toxin phalloidin from Amanita phalloides led to a decrease of G-actin by 70% and an increase of F-actin by 55%. Although the toxin dependent decrease of G-actin was much more pronounced than the decrease after hypotonic treatment, the increase of actin mRNA was similar under both conditions. Simultaneous treatment with hypotonic medium did not result in a further decrease of the G-actin level. On the other hand, the G-actin elevating C2 toxin from Clostridium botulinum completely blocked the effects of osmotic stress on G-actin and actin-mRNA content. The results demonstrate that already an essentially physiological decrease of G-actin without alterations of F-actin results in a substantial enhancement of the actin mRNA level, indicating the physiological significance of this autoregulation.

Actins↗
PubMed1995

Performance of Israeli versus U.S. preschool children on the Miller Assessment for Preschoolers.

OBJECTIVES: The Miller Assessment for Preschoolers (MAP) is a scale that can be used to evaluate preschool children with suspected preacademic problems. Before implementing the MAP in Israel, it was necessary to determine whether the U.S. norms were applicable to the Israeli preschool population. METHOD: In a pilot study carried out in Israel, the Hebrew version of the MAP was administered to 2 age groups of 30 children each. The scores of Israeli children were compared with the U.S. norms on each of the MAP's 27 subtests, the five performance indices, and the total score. RESULTS: There were no significant differences between the Israeli sample and the U.S. standardization sample in either age group on the MAP total score; significant differences were found in both age groups on the Foundations Index and on some specific subtests. Israeli children performed below U.S. norms on the Foundations Index. CONCLUSION: These findings indicate that the performance of Israeli children overall in these two age groups is not significantly different from the performance of U.S. children. If future research demonstrates that these findings are stable across all age groups and for larger samples, the implication is that the MAP can be administered and scored in Israel with the scoring methodology and normative information developed in the United States. However, because of the poorer performance of Israeli children on the Foundations Index, we recommend that specific Israeli norms be developed.

Child, Preschool↗
PubMed1995

Performance of Americans and israelis with cerebrovascular accident on the Loewenstein Occupational Therapy Cognitive Assessment (LOTCA).

OBJECTIVE: The Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) measures the cognitive performance of persons with cerebrovascular accident (CVA). Although this assessment was developed and standardized in Israel, it is frequently used in the United States. The purpose of this study was to identify whether differences in performance on the LOTCA existed between Americans and Israelis who have had strokes. Additionally, this study was designed to compare the performance of persons with right CVA with the performance of persons with left CVA because the normative data for the LOTCA does not include separate information for these two groups. METHOD: The LOTCA was administered to 25 Americans with CVA (19 right CVA and 6 left CVA) and 56 Israelis with CVA (26 right CVA and 30 left CVA). RESULTS: On the majority of LOTCA subtests, there were no significant differences between American and Israeli subjects. Only one subtest, Orientation to Time, revealed significant differences between Americans and Israeli subjects both for subjects with right CVA and subjects with left CVA. Examination of subjects with right CVA versus subjects with left CVA also indicated few differences. Only one subtest, Pegboard Construction, revealed significant differences between subjects with right CVA and subjects with left CVA for both American and Israeli subjects. CONCLUSION: The LOTCA is an appropriate tool for occupational therapists to use in assessing Americans who have had strokes. In addition, for the most part, the subtests of the LOTCA assess cognitive-perceptual abilities that are not specific to the right or left cerebral hemisphere.

Aged↗
PubMed1995

Validity of the Behavioral Inattention Test (BIT): relationships with functional tasks.

OBJECTIVES: The Behavioral Inattention Test (BIT) is a standardized assessment for unilateral visual neglect. It comprises six conventional and nine behavioral subtests. The purpose of this study was to add to the validation of the behavioral subtests. METHOD: Forty Israeli subjects with right cerebrovascular accident (CVA), from both day center and hospital settings, were evaluated on three measures: the BIT, performance tasks, and a checklist of activities of daily living (ADL). RESULTS: Seven of the nine BIT behavioral subtests differentiated significantly between subjects with visual neglect and those without neglect; six of the nine subtests correlated significantly with parallel performance tasks or ADL checklist items. CONCLUSION: These results support the construct and predictive validity of most of the BIT behavioral subtests as functional measures of unilateral neglect, thus, the BIT is recommended for use by occupational therapists. Inclusion of a relative score for right and left omissions within the BIT is recommended.

Activities of Daily Living↗