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Biomedical subjects

S K Dutta

Publications and source records attributed to S K Dutta.

At least 37 records · Page 2Linked to original sources
PubMed2000

Chemistry and insulin-mimetic properties of bis(acetylacetonate)oxovanadium(IV) and derivatives.

The syntheses and the solid state structural and spectroscopic solution characterizations of VO(Me-acac)2 and VO(Et-acac)2 (where Me-acac is 3-methyl-2,4-pentanedionato and Et-acac is 3-ethyl-2,4-pentanedionato) have been conducted since both VO(acac)2 and VO(Et-acac)2 have long-term in vivo insulin-mimetic effects in streptozotocin-induced diabetic Wistar rats. X-ray structural characterizations of VO(Me-acac)2 and VO(Et-acac)2 show that both contain five-coordinate vanadium similar to the parent VO(acac)2. The unit cells for VO(Et-acac)2 and VO(Me-acac)2 are both triclinic, P1, with a = 9.29970(10) A, b = 13.6117(2) A, c = 13.6642(2) A, alpha = 94.1770(10) degrees, beta = 106.4770(10) degrees, gamma = 106.6350(10) degrees for VO(Et-acac)2 and a = 7.72969(4) A, b = 8.1856(5) A, c = 11.9029(6) A, alpha = 79.927(2) degrees, beta = 73.988(2)degrees, gamma = 65.1790(10)degrees for VO(Me-acac)2. The total concentration of EPR-observable vanadium(IV) species for VO(acac)2 and derivatives in water solution at 20 degreesC was determined by double integration of the EPR spectra and apportioned between individual species on the basis of computer simulations of the spectra. Three species were observed, and the concentrations were found to be time, pH, temperature, and salt dependent. The three complexes are assigned as the trans-VO(acac)2.H2O adduct, cis-VO(acac)2.H2O adduct, and a hydrolysis product containing one vanadium atom and one R-acac- group. The reaction rate for conversion of species was slower for VO(acac)2 than for VO(malto)2, VO(Et-acac)2, and VO(Me-acac)2; however, in aqueous solution the rates for all of these species are slow compared to those of other vanadium species. The concentration of vanadium(V) species was determined by 51V NMR. The visible spectra were time dependent, consistent with the changes in species concentrations that were observed in the EPR and NMR spectra. EPR and visible spectroscopic studies of solutions prepared as for administration to diabetic rats documented both a salt effect on speciation and formation of a new halogen-containing complex. Compound efficacy with respect to long-term lowering of plasma glucose levels in diabetic rats traces the concentration of the hydrolysis product in the administration solution.

Animals↗
PubMed2000

Phylogenetic characterization of several para- and meta-PCB dechlorinating Clostridium species: 16s rDNA sequence analyses.

The genus Clostridium has more than 127 species, grouped according to their morphology and functions. Nine Clostridium species were identified based on their ability to dechlorinate meta- and para-PCB (polychlorinated biphenyl) contaminated sediments. The phylogenetic relatedness of these PCB-degrading Clostridium species was studied using ribosomal RNA genes. The diversity of small-subunit rRNA genes associated with the domain bacteria was examined using defined operational taxonomic units (OTUs) in samples from PCB contaminated sediments from Lake Medinah, New York. The RFLP (restriction fragment length polymorphism) of the OTVs was measured. OTUs B (105 clones), A (33 clones) and C (45 clones) accounted for 75% of all the 16S rDNA clones expressing anaerobic para- and meta-PCB dechlorinating activity. In this report we describe complete 16S rDNA sequences of OTU-A and OTU-B, and partial rDNA sequences of OTUs C-J. The OTU-B and OTU-I form a phylogenetically related cluster, closely affiliated with Clostridium hydroxybenzoicum strains. OTUs A, C, D, G, H and J also belong to the genus Clostridium, but they represent separate species. OTU-E, a close affiliate to Bacteroides forsynthus, is a meta-PCB dechlorinator. The Cl. hydroxybenzoicum strains (OTU-B) are primarily para-PCB dechlorinators and are the most common. Some less prevalent OTUs (- E, -G, -H and -I), are also mostly para-PCB dechlorinators. Other Clostridium species such as Cl. beijerinckii (OTU-A), Cl. intestinalis (OTU-D) and Cl. thermolacticum (OTU-J) are primarily meta-PCB dechlorinators. Cl. paraputrificum (OTU-C) and Cl. cellulosi (OTU-F), were less prevalent in the total consortium, but they could dechlorinate both para- and meta-PCB. Although a few less prevalent Clostridium species can degrade both para- and meta-PCBs, this study confirms that para- and meta-PCB dechlorinating species are generally phylogenetically different.

Base Sequence↗
PubMed2000

Histopathology of skin lesions in chronic arsenic toxicity--grading of changes and study of proliferative markers.

Chronic arsenic toxicity (CAT) manifests predominantly as cutaneous lesions in the form of melanosis, keratosis and neoplastic changes. We have studied skin biopsies from 42 patients of CAT. Histological study of H/E stained sections showed--hyperkeratosis in 13, parakeratosis in 13, acanthosis in 12, papillomatosis in 24, elongation of reteridges in 21, increased basal pigmentation in 27 and dysplastic changes in 8 cases. Squamous cell carcinoma was present in 2, basisquamous in 1 and basal cell carcinoma in 1 case. Changes of skin lesions after drug DMSA and DMPS therapy compared to placebo were studied. The result was inconclusive. Proliferative activity of skin lesions in CAT were studied by AgNOR stain to assess the biological behaviour of the lesions. AgNOR score showed--normal control 1.08, benign changes (e.g. Hyperkeratosis, parakeratosis, acanthosis, papillomatosis etc.) without dysplasia--1.35, mild to moderate dysplasia--1.735, severe dysplasia--3.0 and carcinoma--3.56. Thus, AgNOR score gives some idea on the biological behaviour of CAT lesions. It is suggested that AgNOR staining should be done regularly along with H&E staining for proper assessment of the cases.

Adolescent↗
PubMed2000

Microwave technique in histopathology and its comparison with the conventional technique.

125 formalin fixed human tissues from different organs and 50 fresh animal tissues were taken. Each tissue piece was divided into two. Fresh animal tissues were fixed and processed in a domestic microwave oven and formalin fixed tissue were only processed in microwave oven. Simultaneous conventional processing was also carried out. Among the fresh tissues, 34 pieces were fixed in 10% formalin and 16 were stabilized in normal saline, with microwave irradiation. For histoprocessing graded ethanol (70% and absolute) for 150 tissues and graded isopropanol (70% and absolute) for 25 tissues were used for dehydration in microwave technique. Chloroform for 95 tissues, xylene for 15 tissues and isopropanol for 65 tissues were used as clearing agent in microwave technique. Liquid paraffin was impregnating agent in all 175 cases. The oven was operated at 50% power for 10 cases and 40% power for 165 cases. Recording of temperature could not be done. Regarding fixation with formalin 80% cases gave satisfactory result, while with normal saline, only 30% cases were satisfactory. Regarding dehydration with ethanol 80% were satisfactory and with isopropanol 60% were satisfactory. Regarding clearing--both chloroform and isopropyl alcohol gave satisfactory results in 80% cases but with, xylene tissues were fragmented and brittle.

Animals↗
PubMed1999

Refined crystal structure (2.3 A) of a double-headed winged bean alpha-chymotrypsin inhibitor and location of its second reactive site.

The crystal structure of a double-headed alpha-chymotrypsin inhibitor, WCI, from winged bean seeds has now been refined at 2.3 A resolution to an R-factor of 18.7% for 9,897 reflections. The crystals belong to the hexagonal space group P6(1)22 with cell parameters a = b = 61.8 A and c = 212.8 A. The final model has a good stereochemistry and a root mean square deviation of 0.011 A and 1.14 degrees from ideality for bond length and bond angles, respectively. A total of 109 ordered solvent molecules were localized in the structure. This improved structure at 2.3 A led to an understanding of the mechanism of inhibition of the protein against alpha-chymotrypsin. An analysis of this higher resolution structure also helped us to predict the location of the second reactive site of the protein, about which no previous biochemical information was available. The inhibitor structure is spherical and has twelve anti-parallel beta-strands with connecting loops arranged in a characteristic beta-trefoil fold common to other homologous serine protease inhibitors in the Kunitz (STI) family as well as to some non homologous functionally unrelated proteins. A wide variation in the surface loop regions is seen in the latter ones.

Binding Sites↗
PubMed1998

Novel galactose-binding proteins in Annelida. Characterization of 29-kDa tandem repeat-type lectins from the earthworm Lumbricus terrestris.

Novel type lectins were found in the phylum Annelida, i.e. in the earthworm, tubifex, leech, and lugworm. The lectins (29-31 kDa) were extracted from the worms without the use of detergent and purified by affinity chromatography on asialofetuin-agarose. On the basis of the partial primary structures of the earthworm Lumbricus terrestris 29-kDa lectin (EW29), degenerate primers were synthesized for use in the reverse transcriptase-polymerase chain reaction. An amplified 155-base pair fragment was used to screen a cDNA library. Four types of full-length clones were obtained, all of which encoded 260 amino acids, but which were found to differ at 29 nucleotide positions. Since three of them resulted in non-silent substitutions, EW29 mRNA was considered to be a mixture of at least three distinct polynucleotides encoding the following proteins: Ala44-Gln197-Ile213 (clone 5), Gly44-Gln197-Val213 (clone 7), and Ala44-His197-Ile213 (clones 8 and 9; different at the nucleotide level, but encoding an identical polypeptide). Genomic polymerase chain reaction using DNA from a single worm revealed that the single worm already had four sets of cDNAs. The EW29 protein showed two features. First, the lectin was composed of two homologous domains (14,500 Da) showing 27% identity with each other. When each of the domains was separately expressed in Escherichia coli, the C-terminal domain was found to bind to asialofetuin-agarose as strongly as the whole protein, whereas the N-terminal domain did not bind and only retardation was observed. EW29 was found to exist as a monomer under non-denaturing conditions. It had significant hemagglutinating activity, which was inhibited by a wide range of galactose-containing saccharides. Second, EW29 contained multiple short conserved motifs, "Gly-X-X-X-Gln-X-Trp." Similar motifs have been found in many carbohydrate-recognizing proteins from an extensive variety of organisms, e.g. plant lectin ricin B-chain and Clostridium botulinum 33-kDa hemagglutinin. Therefore, these carbohydrate-recognition proteins appear to form a protein superfamily.

Amino Acid Sequence↗
PubMed1998

Studies with recombinant proteins of Ehrlichia risticii: identification of strain-specific antigen as a protective antigen.

Ehrlichia risticii is the causative agent of Potomac horse fever, an acute infectious disease of equines. To study the role of major antigens of E. risticii in protective immune response, we have expressed the genes of the 55 kDa, 51 kDa and 85/50 kDa-strain-specific antigens of the 90-12 (85 kDa antigen) and 25-D (50 kDa antigen) strains in Escherichia coli using pRSET A, B, C system (Invitrogen, San Diego, CA). Mice immunized with these purified recombinant proteins of E. risticii developed strong and specific humoral immune response. The recombinant 85 kDa antigen of the 90-12 strain protected mice against challenge infection with both E. risticii strains, whereas its homologue from the 25-D strain, the recombinant 50 kDa antigen, protected mice against only the homologous strain challenge, but not against the heterologous 90-12 strain. Sera from mice immunized with the 85- or 50-kDa antigens did not inhibit the replication of cell-free Ehrlichiae in in vitro neutralization assays. Sera from normal mice and mice immunized with other antigens caused non-specific neutralization of E. risticii. Immunoglobulin G from mice immunized with the 51 kDa protein of the 90-12 strain caused partial in vitro neutralization of both strains of E. risticii. These studies demonstrate that the 85/50-kDa-strain-specific antigen of E. risticii is involved in immunoprotection against PHF.

Animals↗
PubMed1998

Cloning and molecular analysis of genes encoding two immunodominant antigens of Ehrlichia risticii.

Ehrlichia risticii, the causative agent of Potomac horse fever, is an obligate intracellular rickettsial organism. To understand the role of 55 and 51 kilodalton immunodominant antigens of E. risticii in strain variation, their genes from the 25-D and 90-12 strains were cloned, sequenced, and expressed in E. coli. Sequence analysis revealed that the gene for the 55 kDa antigen was present in a heat shock operon along with the gene for a ;10 kDa protein. Homology searches indicated that the 55 kDa antigen and the 10 kDa protein were homologues of E. coli GroEL and GroES proteins, respectively. There was no nucleotide sequence difference between the genes of the 55 kDa antigen, nor between the entire operons, from both strains of E. risticii. The sequence-based estimation of the sizes of the putative mature 51 kDa antigens of the 90-12 and 25-D strains were 52.7 kDa and 52.9 kDa, respectively. The 51 kDa antigens from the 90-12 and 25-D strains shared a 98% identity in their deduced amino acid sequences. The difference in some of the amino acids may be responsible for variation in their mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, where the 51 kDa antigen of the 25-D strain migrates towards a ;2 kDa lower molecular weight region. In Western blots, a 155 kDa protein that appeared to be a trimer product of the 51 kDa antigen was identified. The 55 and 51 kDa antigens were overexpressed in E. coli using a commercial expression system, pRSET A,B,C (Invitrogen Inc., San Diego, CA, U.S. A.). The purified recombinant proteins cross-reacted with antisera to E. canis and E. sennetsu.

Amino Acid Sequence↗
PubMed1998

Identification and analysis of PCB dechlorinating anaerobic enrichments by amplification: accuracy of community structure based on restriction analysis and partial sequencing of 16S rRNA genes.

The composition of polychlorinated biphenyl (PCB) dechlorinating mixed communities was analysed by restriction fragment length polymorphism of PCR amplified rDNAs (ARDRA) and partial sequencing of 16S rRNA genes amplified from PCB degrading enrichments. Restriction analysis confirms that the 16S rRNA genes amplified from PCB dechlorinating communities vary depending on the PCB congener dechlorinated. Comparison of 16S rRNA sequences to published ribosomal databases indicates that the two most abundant Operational Taxonomic Units (OTUs) appear to be species of the genus Clostridium. The amount that the amplification procedure contributed to this result was determined by varying the amplification procedure and by creating an artificial template mixture. Varying the amount of template by sixfold in the amplification did not affect the distribution of OTUs but the number of OTUs observed decreased with decreasing template concentration. Comparison of products amplified from mixtures of 16S rDNA clones indicates that the more abundant Clostridium OTU did not amplify more efficiently than those of less abundant OTUs. Hybridization to a probe designed to detect the most abundant OTUs indicates that two other OTUs are closely related to this Clostridium species.

Bacteria, Anaerobic↗
PubMed1998

Zinc metabolism in patients with exocrine pancreatic insufficiency.

OBJECTIVE: Metabolism of zinc was studied by administering radioactive zinc (Zn65), and by performing metabolic balance studies in eight patients with exocrine pancreatic insufficiency and eighteen control subjects. METHODS: Retention of radioactive zinc was measured by total body counter, and its urinary and fecal excretion by gamma scintillation counter. Metabolic balance studies were carried out by measuring dietary zinc intake as well as fecal and urinary excretion of zinc by atomic absorption spectrophotometry in this group of patients. RESULTS: These studies revealed a 50% reduction in intestinal absorption of Zn65 in patients with exocrine pancreatic insufficiency as compared to alcoholic and non-alcoholic control subjects. In addition, there was a 2 to 4 fold increase (p<0.05) in urinary excretion of zinc in subjects with pancreatic disease. In pancreatic insufficiency, reduced zinc absorption and increased urinary zinc excretion were balanced by lower (p<0.05) endogenous excretion of zinc as evidenced by reduced excretion of Zn65 in feces during the second 4-day period. The mean biological half-life of Zn65 tended to be lower in patients with pancreatic insufficiency as compared to alcoholic control subjects, however the difference did not reach statistical significance. CONCLUSION: These observations indicate marked alterations in zinc metabolism in patients with advanced chronic pancreatic disease and provide greater insight into development of zinc deficiency in this group of patients.

Adult↗
PubMed1998

Molecular basis for antigenic variation of a protective strain-specific antigen of Ehrlichia risticii.

Ehrlichia risticii, the causative agent of Potomac horse fever, has recently been isolated from many vaccinated horses with typical clinical signs of the disease. The heterogeneity of the E. risticii isolates obtained from the vaccinated horses necessitates the identification of the molecular basis of strain variations to elucidate the vaccine failure and to aid in the development of an efficient vaccine against this disease. As an attempt, two major cross-reacting surface antigen genes of 50- and 85-kDa antigens, present separately in strains 25-D (isolated in 1984) and 90-12 (isolated in 1990 from a vaccinated horse), respectively, were cloned and sequenced. A comparative sequence analysis revealed differences and similarities between these two antigens with strain-specific sizes (SSA). The 2.5- and 1.6-kb genes coding for the 85- and 50-kDa proteins, respectively, contained many different tandem repeats. The identical repeat motifs were more frequent in the middle of both genes, but the numbers and positions of the repeats were altogether different in the genes. Many of these direct repeats of both genes had exact sequence homology and coded for the same amino acids. The homology of the 5'- and 3'-flanking regions of the two genes was greater than that of the regions in the central part of the genes. A comparative analysis of the deduced amino acid sequences of these two antigen genes indicated eight common domains, which were designated identical domains. Although the sequence homologies of these identical domains were the same, the positions of the domains in their respective strains were completely different. This finding might be one of the bases of antigenic variation between the strains. In addition, there were a few unique regions in both antigen genes where no sequence homology existed. These specific regions were designated unique domains. The 50-kDa protein had two such unique domains, and the 85-kDa protein had six such unique domains. The presence of such unique domains contributed to the large size variation of these SSA. The cross-reactivity of recombinant proteins confirmed the presence of conserved epitopes between these two antigens. The SSA have been determined to be apparent protective antigens of E. risticii.

Amino Acid Sequence↗
PubMed1998

Association of deficiency in antibody response to vaccine and heterogeneity of Ehrlichia risticii strains with Potomac horse fever vaccine failure in horses.

Ehrlichia risticii is the causative agent of Potomac horse fever (PHF), which continues to be an important disease of horses. Commercial inactivated whole-cell vaccines are regularly used for immunization of horses against the disease. However, PHF is occurring in large numbers of horses in spite of vaccination. In a limited study, 43 confirmed cases of PHF occurred between the 1994 and 1996 seasons; of these, 38 (89%) were in horses that had been vaccinated for the respective season, thereby clearly indicating vaccine failure. A field study of horses vaccinated with two PHF vaccines indicated a poor antibody response, as determined by immunofluorescence assay (IFA) titers. In a majority of horses, the final antibody titer ranged between 40 and 1,280, in spite of repeated vaccinations. None of the vaccinated horses developed in vitro neutralizing antibody in their sera. Similarly, one horse experimentally vaccinated three times with one of the vaccines showed a poor antibody response, with final IFA titers between 80 and 160. The horse did not develop in vitro neutralizing antibody or antibody against the 50/85-kDa strain-specific antigen (SSA), which is the protective antigen of the original strain, 25-D, and the variant strain of our laboratory, strain 90-12. Upon challenge infection with the 90-12 strain, the horse showed clinical signs of the disease. The horse developed neutralizing antibody and antibody to the 50/85-kDa SSA following the infection. Studies of the new E. risticii isolates from the field cases indicated that they were heterogeneous among themselves and showed differences from the 25-D and 90-12 strains as determined by IFA reactivity pattern, DNA amplification finger printing profile, and in vitro neutralization activity. Most importantly, the molecular sizes of the SSA of these isolates varied, ranging from 48 to 85 kDa. These studies suggest that the deficiency in the antibody response to the PHF vaccines and the heterogeneity of E. risticii isolates may be associated with the vaccine failure.

Animals↗
PubMed1998

Enolase activity in chicken embryo primary retina cells is not affected by exposure to a 60-Hz electric field.

This study was to determine the extent of alteration of enolase specific activities in chicken embryo retina primary cells in culture when exposed to an ELF (extremely low frequency) electric field at 60 Hz. Results showed no alteration of enolase activity and enolase mRNA levels. In this study, sham vs. control experiments were also conducted to neutralize ambient AC magnetic fields, stray magnetic fields and variations in field uniformity. Under similar conditions, the specific activity of enolase is decreased in neuroblastoma cell line (NG108). It is apparent from this study that primary cells either are not affected by these exposure conditions or the effect is transient and warrants no damage.

Animals↗
PubMed1997

Suspected ehrlichial infection in five cats from a household.

Ehrlichiosis is a poorly recognized condition of cats that may be associated with anemia, leukopenia, thrombocytopenia, or dysproteinemia. Affected cats may have indirect fluorescent antibody titers to Ehrlichia canis and E risticii. We reviewed the clinical evaluation and response to treatment of 5 cats in a household where ehrlichial disease was suspected as the cause of recurrent leukopenias and thrombocytopenias. All of the cats had E risticii indirect fluorescent antibody titers and western blot confirmation of antibodies to 4 of the 9 major antigens of E risticii. Response to doxycycline was monitored serologically and hematologically in each cat, and indicated that administration of doxycycline at a dosage of 10 mg/kg of body weight, PO, every 12 hours, for a minimum of 21 days is necessary for treatment of this condition.

Animals↗