Comparison of critical and lowest-Landau-level scaling of the specific heat of several YBa2Cu3O7- delta single crystals.
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Journal Article↗
Biomedical subjects
S Chowdhury
Publications and source records attributed to S Chowdhury.
CCAAT/enhancer-binding protein beta (C/EBP beta) binds and activates while hepatocyte nuclear factor-4 (HNF-4) does not bind but represses the liver-type arginase promoter.
In an attempt to elucidate the mechanism governing liver-specific transcription of the arginase gene, we previously detected two protein-binding sites designated footprint areas A and B at positions around--90 and --55 bp, respectively, relative to the transcription start site of the rat arginase gene. Based on the finding that area A was bound by a liver-selective factor(s) related to CCAAT/enhancer-binding protein (C/EBP), we performed cotransfection assay and showed that C/EBP family members and a related factor, albumin D-element-binding protein (DBP) stimulate transcription from the arginase promoter. In addition to area A, a recombinant C/EBP beta protein bound to area B, which appeared to be primarily responsible for activation by C/EBPs. We unexpectedly found that the arginase promoter activity stimulated by C/EBPs and DBP was repressed by another liver-enriched transcription factor, hepatocyte nuclear factor-4 (HNF-4). Analysis of chimeras formed between the arginase promoter and the herpes simplex virus thymidine kinase promoter allowed us to delimit the negative HNF-4-responsive element into the region overlapping with footprint area B. However, no apparent binding of HNF-4 was observed in this negative element. We speculate that HNF-4 is involved in fine regulation of the arginase gene in the liver or shutdown of the gene in nonhepatic tissues without direct binding to the promoter region.
Animals↗
Conjunctival impression cytology with transfer (CICT) to detect pre-clinical vitamin A deficiency among slum children in India.
In order to establish a method usable in the field for diagnosis of pre-clinical vitamin A deficiency, conjunctival impression cytology with transfer (CICT) was used in 200 normal slum children aged 6-120 months in Chandigarh, India. Conjunctival impressions taken on cellulose acetate paper were transferred to glass slides which were fixed in ethanol and stained with alcian blue and carbol fuchsin. Sixty samples of cellulose acetate paper were preserved after transfer of impression and were stained later. Transfer was complete in forty-eight samples and in the other twelve it was incomplete. Conjunctival impressions on paper and slide of these twelve cases were comparable. At a plasma retinol concentration of < 0.70 mumol/l measured by HPLC the sensitivity, specificity and positive predictive values of CICT were 90.59%, 100% and 100% respectively. Compared with conventional conjunctival impression cytology, CICT is less time consuming, cheaper and comparable in validity. It is thus more suitable than the conventional method for mass screening.
Child↗
Induction of the C/EBP beta gene by dexamethasone and glucagon in primary-cultured rat hepatocytes.
The synthetic glucocorticoid, dexamethasone, and glucagon cooperatively elevated the level of mRNA for the transcription factor CCAAT/enhancer binding protein beta (C/EBP beta) in primary-cultured rat hepatocytes. In response to dexamethasone and/or glucagon, C/EBP beta mRNA started to increase as early as 30 min, reached a maximum within 2 h, and then gradually decreased. The administration of cycloheximide, a protein synthesis inhibitor, led rather to an increase in C/EBP beta mRNA, which suggested that a labile negative protein factor(s) is involved in regulation of the C/EBP beta mRNA level. Cycloheximide further augmented the increases in C/EBP beta mRNA by dexamethasone and/or glucagon. Therefore, C/EBP beta mRNA accumulation in response to these hormones is apparently independent of ongoing protein synthesis. The elevation of the C/EBP beta mRNA level by these hormones was accounted for by increases in the rate of transcription of the C/EBP beta gene, as deduced on nuclear run-on analysis. Gel mobility shift analysis revealed that the DNA-binding activity of C/EBP beta was increased cooperatively by dexamethasone and glucagon. These results suggest that the C/EBP beta gene is primarily induced by glucocorticoids and/or glucagon and that the accumulated C/EBP beta protein is then involved in secondary activation of target genes in response to these hormones in the liver.
Animals↗
Reactivity of various leishmanial antigens in a direct agglutination test and their value in differentiating post-kala azar dermal leishmaniasis from leprosy and other skin conditions.
A direct agglutination test (DAT) for the detection of post-kala azar dermal leishmaniasis (PKDL) was evaluated in conditions that simulate the disease clinically or immunologically. A reference strain of Leishmania donovani (LEM 1399), and antigen preparations from Leishmania isolates from Bangladeshi patients with post-kala azar dermal leishmaniasis or visceral leishmaniasis were used. A titre of at least 51,200 was obtained in tests of patients with PKDL with all three antigens, whereas a maximum titre of 1600 was recorded in patients with cutaneous leishmaniasis, mucocutaneous leishmaniasis or leprosy. Antigens from dermal isolates of L. tropica (LV 140) and L. braziliensis (LV 65) yielded titres of 1600-6400 in patients with PKDL. The lowest titre recorded in 70 patients tested with the homologous PKDL antigen was 409,600. In patients with leprosy, cutaneous leishmaniasis, syphilis, onchocerciasis, tuberculosis, blastomycosis or vitiligo, titres ranged from 100 to 1600. Tha DAT is better than current parasitological and histopathological methods for the diagnosis of PKDL in areas in which leprosy is co-endemic.
Agglutination Tests↗
Scatter factor binds to thrombospondin and other extracellular matrix components.
Scatter factor (SF) is an angiogenic growth factor that stimulates motility and invasion of carcinoma cells. SF is present in the extracellular matrix (ECM) of breast cancers, where it might act to promote tumor cell invasion and angiogenesis. To investigate how SF is incorporated into the ECM, we studied the binding of SF to various ECM components using a solid-phase binding assay based on the SF enzyme-linked immunosorbent assay. We found that SF binds to a variety of ECM molecules, with different binding capacities. The highest SF binding capacities were observed for thrombospondin-1 (TSP-1), fibronectin (Fn), and heparan sulfate proteoglycan, although SF did not bind to albumin. Mature two-chain SF and precursor single-chain SF bound approximately equally well to TSP-1 and Fn. Moreover, two SF alpha-chain peptides (NK1 and NK2) both bound to TSP-1 and Fn, suggesting that the whole SF molecule is not required for binding. Based on binding competition assays, TSP-1 exhibited higher affinity for SF than did nine other ECM molecules, including Fn and heparan sulfate proteoglycan. Although heparin in solution potently inhibited the binding of SF to TSP-1-coated surfaces, even very high concentrations of heparin could not elute SF already bound to TSP-1. SF binding was modulated by binding interactions among ECM molecules (TSP-1-Fn, TSP-1-collagen I, and Fn-collagen I), suggesting that the matrix capacity to bind SF depends upon its exact composition. SF bound in a dose-dependent fashion to ECMs secreted by three human breast carcinoma cell lines. Binding of SF to matrices from all three cell lines was significantly inhibited by preincubation of the matrices with antibodies against TSP-1, whereas antibodies against several other ECM components were less effective or ineffective in inhibiting SF binding. In addition, TSP-1 markedly inhibited chemotaxis of microvascular endothelial cells toward SF and SF-induced angiogenesis in the rat cornea neovascularization assay. Our findings suggest that 1) SF interacts with a variety of ECM components, 2) high affinity SF-TSP-1 interactions may mediate the binding of SF to the breast cancer matrix, and 3) the SF-TSP-1 interaction may contribute to modulation of angiogenesis. Possible implications of these findings for tumor angiogenesis are discussed.
Animals↗
Structure of two cecropin B-encoding genes and bacteria-inducible DNA-binding proteins which bind to the 5'-upstream regulatory region in the silkworm, Bombyx mori.
Two genomic DNAs encoding cecropin B (CecB), an antibacterial protein from Bombyx mori, were cloned and sequenced. The number of CecB genes was estimated to be more than four copies per haploid by genomic Southern blotting. Two genes, CecB1 and CecB2, were located tandemly within 12 kb in the same orientation. These two genes encoded identical amino acids, though 15 nucleotides (nt) were different in the coding region and the intron size varied. About 90% of the nt spanning 800 bp in the 5'-untranslated region (UTR) were identical between the two genes. This 5'-flanking region contained characteristic sequences such as a repetitive element of B. mori (Bm1), an interleukin-6 response element (IL-6 RE), and two putative lipopolysaccharide (LPS) response elements (LPS RE). An electrophoretic mobility shift assay (EMSA) showed that the fat body contains at least three different nuclear proteins inducible by bacteria which bind to the 5'-UTR, suggesting that these proteins may be involved in CecB expression triggered by bacteria.
Amino Acid Sequence↗
cDNA cloning and gene expression of lebocin, a novel member of antibacterial peptides from the silkworm, Bombyx mori.
A cDNA encoding lebocin, a novel member of insect antibacterial peptides, was isolated from the fat body cDNA library of Bombyx mori larvae immunized with Escherichia coli. The cDNA was 844 bp long and had an open reading frame (ORF) containing a probable signal peptide (16 amino acids), a putative prosegment (104 amino acids) and a mature peptide (32 amino acids) followed by 27 additional amino acids at its carboxyl-terminus. Northern blot analysis showed that lebocin gene expression was inducible by bacterial injection, occurred tissue-specifically in the fat bodies and continued at least for 48 h post-infection. These results suggest that lebocin has a unique precursor structure and shows typical gene expression pattern as insect antibacterial peptide.
Amino Acid Sequence↗
Baculovirus-mediated production of the human growth hormone in larvae of the silkworm, Bombyx mori.
To express the cDNA encoding human growth hormone (hGH) in larvae of Bombyx mori, B. mori nuclear polyhedrosis virus (BmNPV) was employed as an expression vector. For the construction of the recombinant virus, the hGH cDNA was inserted into the downstream of the strong polyhedrin promoter to achieve a high level expression. Immunoblot analysis revealed that the virus-mediated hGH was synthesized in the larvae and secreted into the hemolymph. The yield of the recombinant hGH synthesized in the larvae reached to a level of 160 micrograms/ml of hemolymph after purification. The purified recombinant hGH was confirmed to have both the same molecular weight and amino acid sequence at its N-terminal region as those of the natural counterpart. In addition, the biological activity of the recombinant hGH was comparable to that of the natural hGH in the growth-stimulating effect on rat Nb 2 Node lymphoma cells.
Animals↗
Expression of scatter factor in human bladder carcinoma.
BACKGROUND: Scatter factor (SF) is a protein secreted by stromal (supporting) cells that induces disruption of intercellular junctions and stimulates motility and invasiveness of carcinoma cells. SF is also a potent inducer of angiogenesis (new blood vessel formation), a process required for tumor growth and dissemination. Invasion and angiogenesis are characteristics of biologically aggressive tumors, suggesting that the accumulation of SF within tumors might promote progression to a more malignant phenotype. PURPOSE: This study was designed to determine if SF is overexpressed in carcinoma of the bladder and to evaluate the potential mechanisms that might account for such overproduction. METHODS: We measured the SF content in urine from 20 patients with carcinoma of the bladder and various control groups. We also measured expression of SF in bladder tumor extracts, histologic sections of tumors, and cell culture models, using a variety of techniques, including enzyme-linked immunosorbent assays, immunohistochemistry, and Western and Northern blot analyses. Statistical comparisons were performed using two-tailed t tests. RESULTS: Urinary SF content was found to be significantly elevated in patients with bladder carcinoma as compared with normal control subjects (P < .001), patients with benign prostatic hypertrophy (P = .0055), and patients with prostate carcinoma, another genitourinary malignancy (P = .002). Extracts of bladder cancers, especially those from high-grade, invasive tumors, contained very high levels of SF. Both SF and its proto-oncogene (c-met)-encoded receptor were detected in bladder carcinoma tissue sections by immunostaining. Three different bladder carcinoma cell lines produced no detectable SF but produced very high titers of a high-molecular-weight (> 30 kd), heat-sensitive protein that stimulates SF production by stromal cell types. High titers of a similar SF-inducing activity were detected in vivo, in bladder carcinoma extracts, and in the urine of patients with bladder carcinoma. CONCLUSIONS: Our results suggest that SF is overproduced in bladder carcinomas and accumulates within the tumor and in the urine. Overproduction of SF may result from an abnormal urothelial-stromal interaction in which dysplastic or carcinomatous urothelium secretes factors that stimulate SF expression by bladder wall stromal cells. IMPLICATION: Quantitation of SF in the urine and tumor deserves further study as a possible marker of urothelial malignancy.
Blotting, Northern↗
Occurrence of novel types of nitric oxide synthase in the silkworm, Bombyx mori.
Nitric oxide (NO) synthase activity was detected in fat body and the Malpighian tubles of the silkworm, Bombyx mori. Main NO synthase activity in the fat body was Ca(2+)/calmodulin-dependent, inducible by bacterial lipopolysaccharide (LPS) and required NADPH, FAD, FMN, dithiothreitol (DTT) and tetrahydrobiopterin (BH4) as cofactors for the full expression of the activity. The Malpighian tubles contained two types of NO synthase. One was Ca(2+)-independent, calmodulin-dependent and constitutive and the other was Ca(2+)-dependent and constitutive. The former NO synthase required the same cofactors as fat body NO synthase. The activity of Malpighian tuble NO synthases increased dramatically at the end of the last instar period, just prior to spinning. These results indicate that B. mori contains new types of NO synthase, suggesting the wide distribution and different characteristics of this enzyme among vertebrates and invertebrates.
Amino Acid Oxidoreductases↗
Characterization of a Bombyx mori cDNA encoding a novel member of the attacin family of insect antibacterial proteins.
A Bombyx mori cDNA was cloned that hybridized with Hyalophora cecropia attacin probe and its nucleotide sequence was determined. This cDNA consisted of 846 nucleotides and the deduced amino acid sequence showed that the cDNA encodes an attacin precursor protein. The putative mature protein of B. mori attacin had 70.4, 68.3 and 18.8% identity in amino acid sequences with that of H. cecropia acidic and basic attacins and Sarcophaga peregrina sarcotoxin IIA, respectively. B. mori and H. cecropia attacins and S. peregrina sarcotoxin IIA had two subdomains in each G domain, suggesting that common amino acid residues in the subdomains are conserved during evolution and plays an important role in the activity of the antibacterial proteins. Expression of B. mori attacin gene was rapidly induced by the injection of Escherichia coli cells into B. mori larvae and continued at least for 48 h mainly in fat bodies and hemocytes.
Amino Acid Sequence↗
The role of bronchodilators in the management of bronchiolitis: a clinical trial.
A randomized clinical trial was conducted on young children with bronchiolitis admitted to hospital with moderate illness to determine the efficacy of the bronchodilators Salbutamol and ipratropium bromide, either as a single drug or in combination, given as a nebulized solution, compared with a normal saline placebo. Eighty-nine patients, aged from 23 days to 11 months, were randomized into four groups, depending on administered drug or placebo, as follows: group 1--Salbutamol (n = 20); group 2--ipratropium bromide (n = 23); group 3--combined Salbutamol and Ipratropium bromide (n = 24); group 4--normal saline (n = 22). The groups were identical with respect to age, sex, family history of atopy, respiratory syncytial virus (RSV) positivity and enrollment score. They were scored using the clinical parameters of wheezing, retractions and respiratory rate at enrollment, at 30 and 60 minutes after the first nebulization, and after 60 minutes following completion of subsequent nebulization at 6, 12, 24 and 36 hours. We did not find any significant difference in the rate of improvement and the final score (p = 0.49) in the four groups. The same finding was also noted in children aged more than 3 months (p = 0.35) and in those positive for RSV infection (p = 0.18). The lengths of hospitalization in the four groups were also similar (p = 0.79). It is concluded that there is no role for the nebulized bronchodilators Salbutamol and Ipratropium bromide, either as a single agent or in combination, compared with normal saline placebo in treating young children in hospital with bronchiolitis.
Administration, Inhalation↗
Evaluation of cleaving agents other than trypsin in direct agglutination test for further improving diagnosis of visceral leishmaniasis.
Trypsin treatment of Leishmania promastigote antigen has proved to be indispensible in the direct agglutination test (DAT) for the diagnosis of visceral leishmaniasis (VL) and canine visceral leishmaniasis (CVL). In the present study four antigen batches were prepared with pronase (400 micrograms/ml), lipase (0.45% [wt/vol]), pancreatin (0.3% [wt/vol]), or 2-mercaptoethanol (2-ME) (1.2% [vol/vol]) at a ratio of 20:1 versus promastigote packed cell volume or a density of 10(8)/ml. Batches prepared in this way performed satisfactorily when compared with the performance of the initial trypsinated antigen. Even higher was the sensitivity and specificity of the 2-ME-processed antigen, scoring a minimum DAT titer of 1:102,400 in the VL and CVL group and a maximum of 1:400 in the negative control group. Corresponding titers ranging from 1:6,400 to 1:12,800 and 1:800 to 1:1,600 were obtained with the antigen variants processed with pronase, lipase, pancreatin, or trypsin. By combining the use of indigenous Leishmania donovani subspecies from Sudan, Bangladesh, or Morocco and incorporating 2-ME instead of trypsin in the antigen processing step, a threefold increase in titer was attained in sera from the respective areas where VL is endemic. 2-ME-processed antigen suspensions maintained stability at 4 degrees C for up to 9 months, as evidenced by the absence of autoagglutination and the reproducibility of DAT readings with standard sera. The specificity of DAT was further improved by supplementation of the sample diluent with 0.03 M urea and incubation of the test plates at 37 degrees C for 1 h. Titers ranging from 1:200 to 1:12,800 in the sera of patients and laboratory animals infected with various trypanosoma species were significantly reduce (</=1:200) or were rendered negative dilution of 1:25. Regardless of the infections caused by trypanosoma species, the sensitivity, specificity, and predictive value of a positive or negative test in DAT were 100%. Sera from patients who formerly had VL and who had been treated 6 to 36 months earlier remained reactive (>/=1:51,200) against 2-ME-processed antigen, despite the incorporation of urea into the DAT.
Agglutination Tests↗
Lipopolysaccharide-lipophorin complex formation in insect hemolymph: a common pathway of lipopolysaccharide detoxification both in insects and in mammals.
The formation of the lipophorin-lipopolysaccharide (LPS) complex in Bombyx mori hemolymph and its role in LPS detoxification were explored. LPS, an antibacterial protein inducer in insects, was injected into B. mori larvae. Analytical density gradient ultracentrifugation revealed that after injection the LPS peak shifts to a zone of lower density with time. The shifted peak was identified as the lipophorin-LPS complex. This complex formation was also achieved in an in vitro mixture of cell-free hemolymph and LPS at 25 degrees C but not at 1 degree C. The lipophorin-LPS complex had a significantly lower capacity to elicit the mRNA of cecropin B, an antibacterial protein. The biological activity of reextracted LPS from the complex was slightly reduced in the Limulus test and no structural modification was observed in sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE). These results suggested that the formation of lipophorin-LPS strikingly reduces the cecropin inducibility of LPS without any structural change in LPS. Similar serum lipoprotein-LPS complex formation and reduction of biological activities of LPS were also observed in mammals. We, therefore, suggest that the formation of the serum lipoprotein-LPS complex is a common pathway to inactivate LPS both in insects and in mammals.
Animals↗
Impact of health education on the feeding of green leafy vegetables at home to children of the urban poor mothers of Bangladesh.
To evaluate the impact of health education on mothers, on the feeding of their children green leafy vegetables (GLV) at home, we studied 160 children aged 6 to 35 months and their mothers in two intervention groups and one comparison group. The mothers of the first intervention group (n = 44) were given health education including a feeding demonstration, by offering a single meal of cooked GLV to their children. The mothers in the second intervention group (n = 36) received health education only. Mothers of both the intervention groups were visited at home after eight weeks of intervention without prior notice, and for each of them an immediate neighbourhood mother having a child in the same age range was selected as a comparison mother (n = 80). During this visit, mothers were asked whether they had cooked GLV that day and fed these to their children; this was confirmed by spot-checking. Also, mothers were interviewed to elicit their perceptions about GLV. The percentages of mothers who thought that GLV are good for health were 88.7%, 86.1% and 76.2% in groups 1, 2 and comparison respectively (P = 0.06). However, the percentages of mothers who actually fed their children GLV were 57%, 64% and 26% in groups 1, 2 and comparison group respectively (P < 0.001). The influence of health education on GLV feeding persisted after controlling for the effect of maternal literacy (Mantel Haenszel chi-square = 16.99; P < 0.0001) and family income (Mantel Haenszel chi-square = 17.36; P < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)
Bangladesh↗
The radiation dosimetry and normal value study of 99mTc-HMPAO-labeled leukocytes.
RATIONALE AND OBJECTIVES: Indium-111 (111In)-labeled leukocyte scanning has been used frequently in patients suspected of having infections. Recently, technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) has been used to label leukocytes. This study was undertaken to determine the distribution and dosimetry of 99mTc-HMPAO leukocytes in healthy subjects. METHODS: Five healthy volunteers had leukocytes labeled with 99mTc-HMPAO. After injection of the labeled leukocytes, whole body images and blood and urine samples were obtained at multiple time points. RESULTS: Visual interpretation of the images demonstrated significant bowel activity as early as 2 hours and increasing with time such that one the 8- and 24-hour images, the amount of bowel activity would preclude using 99mTc-HMPAO leukocyte scanning for abdominal processes. The dosimetry for this study is similar to that of other studies and is in an acceptable diagnostic range. CONCLUSIONS: 99mTc-HMPAO leukocyte studies are an acceptable alternative to 111In-labeled leukocyte studies in terms of dosimetry. Use of such studies in the abdomen should be limited to early images, usually before 2 hours, to avoid confusion with the normal route of excretion in the bowel.
Female↗
Familial testotoxicosis.
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Child, Preschool↗