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Biomedical subjects

Z Zaman

Publications and source records attributed to Z Zaman.

At least 19 recordsLinked to original sources
PubMed2002

Vitamin D deficiency in guinea pigs: exacerbation of bone phenotype during pregnancy and disturbed fetal mineralization, with recovery by 1,25(OH)2D3 infusion or dietary calcium-phosphate supplementation.

Vitamin D (D) deficiency during human pregnancy appears to disturb fetal growth and mineralization, but fetal development is normal in D-deficient rats and vitamin D receptor gene-ablated mice. We used the guinea pig model to investigate maternal and fetal effects of D deficiency. Pregnant (Pr) and nonpregnant (NPr) animals were fed a D-replete (+D) or D-deficient diet (-D) for 8 weeks. We further studied whether the effects of a -D diet are reversed by continuous 1,25(OH)2D3 infusion (-D+1,25) and/or by a lactose-, Ca- and P-enriched D-deficient diet (-D+Ca/P). Bone analyses included histomorphometry of the proximal tibiae, dual-energy X-ray absorptiometry (DXA), and quantitative computed tomography (QCT) of the femora. Depletion of 25(OH)D3 and 1,25(OH)2D3 levels and the D-deficiency syndrome were more severe in pregnant animals. Indeed, Pr/-D but not NPr/-D guinea pigs were hypophosphatemic, and showed robust increases in growth plate width and osteoid surface and thickness; in addition, bone mineral density on DXA was lower in Pr/-D animals only, which was exclusively in cortical bone on QCT. Bone phenotype was partly normalized in Pr/-D+1,25 and Pr/-D+Ca/P animals. Compared with +D fetuses, -D fetuses had very low or undetectable 25(OH)D3 and 1,25(OH)2D3, were hypercalcemic and hypophosphatemic, and had lower osteocalcin levels. In addition, body weight and total body bone mineral content were 10-15% lower; histomorphometry showed hypertrophic chondrocyte zone expansion and hyperosteoidosis. 1,25(OH)2D3 levels were restored in -D+1,25 fetuses, and the phenotype was partially corrected. Similarly, the fetal +D phenotype was rescued in large part in -D+Ca/P fetuses, despite undetectable circulating 25(OH)D3 and 1,25(OH)2D3. We conclude that pregnancy markedly exacerbates D deficiency, and that augmenting Ca and P intake overrides the deleterious effects of D deficiency on fetal development.

Absorptiometry, Photon↗
PubMed2002

Microscopic haematuria in giant cell arteritis.

Giant cell arteritis (GCA) is traditionally considered to spare the kidney, although an uncontrolled study reported microscopic haematuria in 10 out of 30 patients with GCA. To study the frequency and the characteristics of microscopic haematuria in GCA, we retrospectively studied 42 patients with biopsy-proven GCA, 39 patients with polymyalgia rheumatica (PMR) and 62 control patients >or=60 years of age, admitted to the general internal medicine unit. Patients with pyuria, significant bacteriuria or a known haematuric disorder were excluded. Microscopic haematuria was defined as the presence of >5 red blood cells (RBC) per high-power field (sediment counts) or of >8 RBC/microl (direct counting). Microscopic haematuria was present at presentation in 47.6% of the GCA patients, versus 17.9% of the PMR patients (P = 0.005) and 21.0% of the control patients (P = 0.008). Urinary RBC were predominantly dysmorphic in all GCA patients in whom RBC morphology was assessed (n = 7). Presenting symptoms, renal function, arterial blood pressure and degree of leukocyturia did not differ significantly between GCA patients with or without haematuria. After the initiation of corticosteroid therapy, microscopic haematuria was no longer detectable in 25 of 35 GCA patients (71.4%). Microscopic haematuria of renal origin is frequent but generally benign in patients with GCA. Its presence, if unassociated with blood pressure elevation or renal function deterioration, helps to rule in rather than to rule out the diagnosis of GCA. In the typical setting invasive urologic and nephrologic work-up may not be warranted.

Age Distribution↗
PubMed2002

Blood antioxidant levels in patients with alcoholic liver disease correlate with the degree of liver impairment and are not specific to alcoholic liver injury itself.

BACKGROUND: Enhanced production of reactive oxygen species may play a pathogenic role in alcoholic liver injury. AIMS: To investigate whether various antioxidant parameters in blood are affected in different stages of alcoholic liver disease and how specific the changes are relative to non-alcoholic cirrhosis. METHODS: Patients with alcohol abuse without cirrhosis (n=14), with alcoholic cirrhosis [Child-Pugh scores A (n=9), B (n=5) and C (n=18)] and with non-alcoholic cirrhosis [Child-Pugh score C (n=6)] and healthy controls (n=13) were studied. Levels of reduced glutathione and glutathione peroxidase activity in blood, erythrocytic superoxide dismutase activity and carotenoids, alpha-tocopherol and malondialdehyde in plasma were measured. RESULTS: Levels of reduced glutathione were significantly decreased in Child-Pugh score C cirrhotics, alcoholic or not in origin, whereas oxidized glutathione and glutathione peroxidase activity were not affected. Superoxide dismutase activity and alpha-tocopherol levels were not significantly different in the various groups. Carotenoid levels were significantly lower in alcoholic cirrhotics (Child-Pugh score C) vs. controls. Malondialdehyde levels were elevated only in cirrhotics Child-Pugh score C, alcoholic or non-alcoholic. CONCLUSIONS: Levels of reduced glutathione and malondialdehyde reflect the degree of liver impairment, more than the relation with alcohol intake. Decreases in several antioxidant levels are not specific to alcoholic liver injury.

Adult↗
PubMed2001

Interaction of a transcriptional repressor with the RNA polymerase II holoenzyme plays a crucial role in repression.

The yeast transcriptional repressor Tup1, tethered to DNA, represses to strikingly different degrees transcription elicited by members of two classes of activators. Repression in both cases is virtually eliminated by mutation of either member of the cyclin-kinase pair Srb10/11. In contrast, telomeric chromatin affects both classes of activators equally, and in neither case is that repression affected by mutation of Srb10/11. In vitro, Tup1 interacts with RNA polymerase II holoenzyme bearing Srb10 as well as with the separated Srb10. These and other findings indicate that at least one aspect of Tup1's action involves interaction with the RNA polymerase II holoenzyme.

Cyclin-Dependent Kinase 8↗
PubMed2001

Telomere looping permits gene activation by a downstream UAS in yeast.

In yeast (Saccharomyces cerevisiae), transcriptional activators, such as Gal4 and Gal4-VP16, work ordinarily from sites located in the upstream activating sequence (UAS) positioned about 250 base pairs upstream of the transcription start site. In contrast to their behaviour in mammalian cells, however, such activators fail to work when positioned at distances greater than approximately 600-700 base pairs upstream, or anywhere downstream of the gene. Here we show that, in yeast, a gene bearing an enhancer positioned 1-2 kilobases downstream of the gene is activated if the reporter is linked to a telomere, but not if it is positioned at an internal chromosomal locus. These observations are explained by the finding that yeast telomeres form back-folding, or looped, structures. Because yeast telomeric regions resemble the heterochromatin found in higher eukaryotes, these findings might also explain why transcription of some higher eukaryotic genes depends on their location in heterochromatin.

Chromatin↗
PubMed2001

Blood gas analysis: POCT versus central laboratory on samples sent by a pneumatic tube system.

BACKGROUND: We aimed to compare the results of blood gas analyses, performed at point-of-care and in the central laboratory (CL), on samples sent via a pneumatic tube system (PTS). METHOD: Specimens from two locations (lung function laboratory (LFL) and pneumology wards) were first analysed locally and then sent to the CL via PTS. RESULTS: While none of the blood gas samples from the LFL had air bubbles, 21 samples from the wards (n=31) had air bubbles in them. The mean time difference between the first (POCT) and the second (CL) determinations from LFL was 13.3+/-5.4 min (n=27) and from the wards 20.2+/-11 min. For pO2 the differences between LFL and CL results, for patients undergoing a 100% O2 test, were unacceptably large. For pO2 range 41-407 mm Hg, the difference was -2.4+/-3.2 (n=25). For the samples from the wards, the difference in pO2 between ward (range 37-183 mm Hg) and CL was -13+/-18 mm Hg. CONCLUSION: Irrespective of air bubbles, the transport by PTS has very little or no effect on pH and pCO2. If air bubbles cannot be excluded with certainty, PTS is not an appropriate transport medium for measurement of pO2 on blood gas samples.

Blood Gas Analysis↗
PubMed2001

Unsatisfactory performance of flow cytometer UF-100 and urine strips in predicting outcome of urine cultures.

UF-100 flow cytometer and urine strip results were cross-interpreted to predict culture outcomes. The best negative predictive value was obtained with bacteria at > or =1,000/microl, white blood cells at > or =20/microl, or leukocyte esterase positivity. Nine of 24 false negatives were clinically significant. Thus, UF-100 and urine strip results do not accurately predict the outcome of cultures.

Adolescent↗
PubMed2001

Safely reducing manual urine microscopy analyses by combining urine flow cytometer and strip results.

We aimed to reduce the number of manual urine microscopy examinations safely by cross-interpretation of the Sysmex UF-100 (TOA Medical Electronics, Kobe, Japan) and urine strip results such that microscopy would be performed if there was discordance between the UF-100 and urine strip results. We also evaluated the usefulness of the optional UF-100 expert software. We performed 2 studies: study 1 to establish review rules for eventual microscopic examination; study 2, a validation study. Our review rates were 40% and 48% and those of UF-100 software were 16% and 32% for the 2 studies. Our false-positive and false-negative results, among the samples not flagged for microscopic review, were acceptably low. We did not find a good correlation between the microscopic classification of RBC morphologic features and the classification given by the UF-100. Since incorporation of the automated urine strip reader and the UF-100 in routine use, our manual microscopy has been reduced to less than 40%.

Adolescent↗
PubMed2001

Evaluation of Aution Max AX-4280 automated urine test-strip analyser.

Aution Max AX-4280, an automated urine test-strip analyser, was evaluated in three centres. Method comparison, imprecision, carry-over, linearity, detection limit and drift studies were performed for glucose, protein, blood and leukocytes using Uriflet S 9UB strips. These strips enable measurement of pH, glucose, protein, blood, leukocytes, ketones, bilirubin, urobilinogen and nitrite. Specific gravity is determined by the refractive index method. Within-run and between-day imprecision, assessed using pooled urines and quality control materials, were good. No drift over 24 h or sample carry-over was observed. Method comparison with quantitative methods for glucose, protein and specific gravity yielded good correlations. Ascorbate negatively interfered with haemoglobin, glucose and nitrite measurements. Acetylsalicylic acid lowered pH, the effect being greatest when protein was absent. During the assessment period no malfunction or breakdown was reported. The Aution Max is easy to use and needs minimal maintenance.

Ascorbic Acid↗
PubMed2000

Bimodal role of endogenous interleukin-6 in concanavalin A-induced hepatitis in mice.

Acute concanavalin A (Con A)-induced hepatitis in mice is an animal model for hepatic injury induced by activated T cells. The evolution of hepatic involvement can be followed from hour to hour by measuring serum transaminase levels. We investigated the possible role of endogenous interleukin-6 (IL-6) in this model. We found serum IL-6 levels and splenic IL-6 mRNA during Con A-induced hepatitis to be significantly lower in interferon-gamma (IFN-gamma)-deficient mice, which are resistant against the Con A-induced syndrome, than in wild-type ones, suggesting that systemic IL-6 production favors development of hepatic injury. However, IL-6-deficient mice proved to be more susceptible to the disease than wild-type mice, indicating that endogenous IL-6 plays a predominantly hepatoprotective role. Experiments in which wild-type mice were treated with anti-IL-6 antibodies, before or after Con A challenge, allowed us to reconcile these contrasting observations. The antibody injections resulted in a biphasic alteration of serum IL-6 levels, initial neutralization being followed by rebound increased levels due to accumulation of IL-6 in the form of antigen-antibody complexes. The effect of antibody on disease severity differed depending on the time of injection. Antibody injection at 2.5 h post Con A resulted in delayed disease manifestation, whereas treatment initiated before Con A resulted in accelerated disease. We conclude that endogenous IL-6 plays a bimodal role. IL-6 present before Con A challenge as well as that induced in the very early phase after Con A injection triggers hepatoprotective pathways. Continuation of IL-6 production beyond this early phase, by some other pathway, seems to be harmful to hepatocytes.

Animals↗
PubMed2000

Dysmorphic erythrocytes and G1 cells as markers of glomerular hematuria.

We aimed to assess the utility of the percentage of G cells and dysmorphic erythrocytes in the diagnosis of glomerular hematuria in pediatric patients. We determined the percentage of dysmorphic erythrocytes and G1 cells in urine samples from patients with glomerulonephritis and other renal diseases of non-glomerular origin. There was excellent correlation and agreement between results obtained by counting the cells in counting chambers and in urine sediments. With cut-off values of > or =1%, > or =2%, > or =5%, and 10% for G1 cells, sensitivities for the detection of glomerulonephritis were 62%, 40%, 28%, and 10% and specificities were 89%, 95%, 95%, and 98%. For the dysmorphic erythrocytes cut-off values of > or =10%, > or =20%, 50%, and > or =90% gave respective sensitivities of 95%, 95%, 93%, and 62% and specificities of 24%, 34%, 43%, and 85%. In 38% of cases of biopsy-proven glomerulonephritis no G1 cells were found. For cut-off values of > or =50% dysmorphic erythrocytes and > or =1% G1 cells, the sensitivity and specificity were 60% and 91%. For cut-off values of > or =50% dysmorphic or > or =1% G1 cells, sensitivity and specificity were 93% and 44%. Our results show that neither the percentage of dysmorphic erythrocytes nor the G1 cell count is of adequate sensitivity and specificity to enable reliable differentiation of glomerular and non-glomerular hematurias. Both tests are needed to achieve >90% sensitivity and specificity.

Adolescent↗
PubMed1999

Transcription factor GCN4 for control of amino acid biosynthesis also regulates the expression of the gene for lipoamide dehydrogenase.

The yeast LPD1 gene encoding lipoamide dehydrogenase is subject to the general control of amino acid biosynthesis mediated by the GCN4 transcription factor. This is striking in that it demonstrates that GCN4-mediated regulation extends much farther upstream than simply to the direct pathways for amino acid and purine biosynthesis. In yeast, lipoamide dehydrogenase functions in at least three multienzyme complexes: pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase (which function in the entry of pyruvate into, and metabolism via, the citric acid cycle) and glycine decarboxylase. When wild-type cells were shifted from growth on amino acid-rich to amino acid-deficient medium, the expression of lipoamide dehydrogenase was induced approx. 2-fold. In a similar experiment no such induction was observed in isogenic gcn4 mutant cells. Northern analysis indicated that amino acid starvation affected levels of the LPD1 transcript. In the upstream region of LPD1 are three matches to the consensus for control mediated by GCN4. Directed mutagenesis of each site, and of all combinations of sites, suggests that only one site might be important for the general control response under the conditions tested. Gel-retardation analysis with GCN4 protein synthesized in vitro has indicated that GCN4 can bind in vitro to at least two of the consensus motifs.

Amino Acid Sequence↗
PubMed1999

Transcriptional activation by artificial recruitment in yeast is influenced by promoter architecture and downstream sequences.

The idea that recruitment of the transcriptional machinery to a promoter suffices for gene activation is based partly on the results of "artificial recruitment" experiments performed in vivo. Artificial recruitment can be effected by a "nonclassical" activator comprising a DNA-binding domain fused to a component of the transcriptional machinery. Here we show that activation by artificial recruitment in yeast can be sensitive to any of three factors: position of the activator-binding elements, sequence of the promoter, and coding sequences downstream of the promoter. In contrast, classical activators worked efficiently at all promoters tested. In all cases the "artificial recruitment" fusions synergized well with classical activators. A classical activator evidently differs from a nonclassical activator in that the former can touch multiple sites on the transcriptional machinery, and we propose that that difference accounts for the broader spectrum of activity of the typical classical activator. A similar conclusion is reached from studies in mammalian cells in the accompanying paper [Nevado, J., Gaudreau, L., Adam, M. & Ptashne, M. (1999) Proc. Natl. Acad. Sci. USA 96, 2674-2677].

Gene Expression Regulation, Fungal↗
PubMed1999

Analytical and clinical performance of two cardiac troponin I immunoassays.

Cardiac troponin I assays for Axsym (Abbott Diagnostics, Abbott Park, IL, USA) and Immuno 1 (Bayer Corporation, Tarrytown, NY, USA) analysers were evaluated. Heparin plasma or serum could be used for both assays. Samples were stable for 24 h at ambient temperature, 3 days at 4-8 degrees C and 3 months at -20 degrees C. After 10 months' storage at -80 degrees C, the recoveries were well above 100% by both assays. Total coefficients of variation for Axsym assay were 9.0%, 5.8% and 5.3% at concentrations of 2.6 microg/l, 9.83 microg/l and 34.3 microg/l respectively; for Immuno 1 these were 4.4 %, 1.6% and 1.8% at 2.3 microg/l, 6.27 microg/l and 44.35 microg/l respectively. It was > or =20% at concentration of < or =0.5 microg/l for Axysm assay and < or =0.15 microg/l for Immuno 1 assay. Recoveries were < or =90% at < or =0.22 microg/l on Axsym and at < or =1.47 microg/l on Immuno 1. Neither method showed significant interference with haemoglobin, bilirubin, triglycerides or rheumatoid factor. Correlation between the two methods was excellent (r = 0.997, Y (Axsym) = 4.2X (Immuno 1) +3.2). The highest concentrations detected in 50 healthy subjects were 0.3 microg/l and 0.1 microg/l by Axsym and Immuno 1 methods, respectively. Twelve out of 43 renal failure patients had troponin I 0.13-0.9 microg/l using Axsym method and 4 had levels of 0.07-0.13 microg/l using Immuno 1. In muscle trauma patients, troponin I was undetectable.

Adult↗
PubMed1999

Calciotrophic hormones during experimental hypocalcaemia and hypercalcaemia in spontaneously diabetic rats.

1,25-Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) concentrations have been found to be decreased in diabetic humans and rats. To investigate further the regulation of plasma Ca in diabetes, first we measured Ca(2+), P, Mg, parathyroid hormone(1-34) (PTH), and total and free 1,25(OH)(2)D(3) in male spontaneously diabetic rats 7 and 28 days after the onset of glycosuria. Secondly, we studied changes in the levels of PTH and 1,25(OH)(2)D(3) in response to hypocalcaemia induced by an i.v. infusion of EGTA (2.5%, wt/vol.) for 24 h, and changes in the levels of 1,25(OH)(2)D(3) in response to an i.v. infusion of rat PTH (10 microgram over 24 h) without or with concomitant EGTA infusion (producing hypercalcaemia or normo/hypocalcaemia respectively), in diabetic and control rats. Ca(2+), P, Mg and PTH concentrations remained within the control ranges after 7 and 28 days of glycosuria; 1,25(OH)(2)D(3) concentrations were decreased after 7, but not after 28, days of glycosuria. PTH concentrations showed a similar rise during EGTA-induced hypocalcaemia in control and diabetic rats compared with saline-infused rats, whereas 1,25(OH)(2)D(3) concentrations were unchanged in both groups. Total and free 1,25(OH)(2)D(3) levels were comparably (about 3-fold) increased during PTH, but not during combined PTH and EGTA infusion in control and diabetic rats. Total 1, 25(OH)(2)D(3) concentrations were lower in the diabetic groups infused with saline or PTH than in their respective controls, and there was a similar trend in the PTH+EGTA-infused group; free 1, 25(OH)(2)D(3) levels, however, were normal or increased in the diabetic groups, confirming our previous data. The novel finding of this study is that, despite severe insulin deficiency and altered 1, 25(OH)(2)D(3) levels, the in vivo response of PTH levels to hypocalcaemia and the in vivo response of 1,25(OH)(2)D(3) levels to PTH in diabetic rats are comparable with those found in nondiabetic rats.

Animals↗