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Biomedical subjects

A Bhattacharya

Publications and source records attributed to A Bhattacharya.

At least 181 records · Page 10Linked to original sources
PubMed1992

Can pulse oximetry be used to measure systolic blood pressure?

This study evaluates the use of pulse oximetry to accurately monitor systolic arterial blood pressure in 100 healthy volunteers. Determination of arterial blood pressure using oximetry was made at the disappearance of visual display upon blood pressure cuff inflation, at the reappearance of visual display upon cuff deflation, and by averaging the two. The blood pressures obtained by pulse oximetry were compared with the arterial blood pressures obtained by Korotokoff sounds and noninvasive blood pressure equipment. Good agreement was obtained when the average of oximetry-based systolic blood pressure estimates at the disappearance and reappearance of the waveform were compared with Korotokoff sound pressures and noninvasive equipment pressures. Thus pulse oximetry can be used to measure systolic arterial blood pressure. This technique is specifically important for patients with Takayasu's syndrome (pulseless disease) where conventional techniques often fail to monitor systolic arterial blood pressure.

Adult↗
PubMed1992

Organization of repeated sequences in the region downstream to rRNA genes in the rDNA episome of Entamoeba histolytica.

The E. histolytica rDNA episome consists of a 3.7 kb HindIII fragment located downstream of the rDNA inverted repeats. We have determined the complete nucleotide sequence of this fragment and have shown that it is comprised of two families of short tandem repeats, the 170 bp DraI repeat and the 144 bp ScaI repeat. Each DraI repeat unit consists of 12-mer sequences with near complete homology to yeast consensus autonomously replicating sequence. In addition, a 21-mer subrepeat structure is also present in each unit. The sequence of the ScaI repeat is about 90% homologous with the sequence of another family of 145 bp tandem repeats, the PvuI repeats reported to be present upstream of the rRNA genes (3). Compared with most other parts of the rDNA episome, the downstream region showed frequent restriction fragment length polymorphism. This was due to changes in the number of tandem DraI repeat units. The loss of these repeats might explain how rDNA length heterogeneity observed in the clones of HM1:IMSS could have arisen. On the other hand, the number of ScaI repeat units in these clones remained unchanged. The repeat units found in the 3.7 kb HindIII fragment show superficial resemblance to equivalent regions of the intergenic spacers of higher eukaryotes. Moreover, these repeated sequences seem to be specific for the pathogenic strain of E. histolytica.

Animals↗
PubMed1992

The directional reflectance of the retinal nerve fiber layer of the toad.

Various optical methods for assessing the retinal nerve fiber layer (RNFL) depend on reflected light, but little is known about the characteristics of the RNFL as a reflecting structure. The authors investigated the angular dependence of light reflected by the unmyelinated nerve fibers of the toad eyecup using a small 500-nm light source that could illuminate the retina from various directions and a movable low-power microscope that imaged the retina onto a cooled charge-coupled device in a digital camera system. Measured areas had nerve fiber bundles separated by gaps. Therefore, the reflectance of a bundle alone could be determined from the difference in intensity between the bundle and an adjacent gap. The RNFL reflectance showed striking directional dependence; nerve fiber bundles seen when illuminated from one direction disappeared completely when illuminated from another. Light reflected by a bundle was confined to a conical sheet concentric with the axis of the bundle. The apex angle of the cone was twice the angle between the incident light and the bundle axis, and the orientation of the cone changed with the orientation of the RNFL. This behavior was consistent with the theory of light scattering by cylinders. Therefore, it was concluded that the RNFL reflectance arises from cylindric structures. These results have clinical significance for imaging the RNFL in the human eye because the apparent intensity of the RNFL will depend, not just on its thickness, but also on its orientation relative to the imaging system.

Animals↗
PubMed1991

Biochemical and immunological characterization of exometabolites from an Indian strain of Leishmania donovani promastigotes grown in a chemically defined medium.

Exometabolites (EXOM) of an Indian strain of Leishmania donovani promastigotes isolated from a chemically defined medium by ultrafiltration consisted of proteins, glycoproteins, lipid and lipophosphopolysaccharide (LPPS). LPPS of Mr 40-28 kDa in SDS-PAGE could be labelled metabolically with [32P]-phosphate and recovered in the aqueous phase of hot-phenol-water extraction of EXOM (PE-Aq) along with a glycoprotein of Mr 150-130 kDa (GP150-130). These two molecules could be eluted from DE-52 column with 200 mM NaCl (D2). The 300 mM NaCl (D3) and 400 mM NaCl (D4) eluates from DE-52 column contained one unsaturated polar lipid component. The LPPS had Rf value of 0.65-0.75 in Thin Layer Chromatography (TLC) using saturated phenol water solvent system. EXOM revealed 15 bands in SDS-PAGE of which proteins of Mr 84, 66, 56, 50 and 29 kDa were prominent. When EXOM were fractionated through Con A-Sepharose column, the fraction eluted with alpha-methyl-D-mannoside (Con A-E) had seven bands as revealed by SDS-PAGE of which 25, 16, 13 and 12 kDa glycoproteins were prominent. The antigens present in EXOM can be classified as slower anodic migrating and faster anodic migrating antigens as revealed by immunoelectrophoresis (IEP). The slower anodic migrating antigens, LPPS and GP150-130 recovered in PE-Aq and D2 did not cross-react with kala-azar patients' sera but cross-reacted with homologous anti-promastigote sera. Two faster anodic migrating antigens which could be recovered in organic phase of hot phenol extraction of EXOM (PE-O) and eluted in D3 and D4 and Con A-E, cross-reacted with kala-azar patients' sera. The antigens of both the classes were sensitive to periodic acid oxidation.

Animals↗
PubMed1991

Xenopus liver ferritin H subunit: cDNA sequence and mRNA production in the liver following estrogen treatment.

In vitro translation of liver mRNA from estrogen-treated Xenopus frogs yields two abundant polypeptides in the range of 20 kDa. DNA clones for one of these translation products were isolated and shown to be complementary to mRNA for the heavy subunit of ferritin. The predicted Xenopus amino acid sequence shares about 86% identity with the ferritin heavy chain from bullfrogs and about 70% identity with the comparable mammalian and avian proteins. Clone identity was confirmed by hybridization selection followed by in vitro translation into translation products of 19.5-20 kDa. The nearly full-length cDNA clone, termed XlferH1, comprises 868 nucleotides plus 22 adenosines of the poly(A) tail, including 134 nucleotides of the 5'-untranslated region, a 528-base coding region for 176 amino acids, and a 206-nucleotide 3'-untranslated region. The clone lacks 22 nucleotides from the 5' end of the mRNA. The level of ferritin mRNA in the liver of estrogen-treated frogs was determined over time. The amount of this mRNA relative to total RNA decreased about 3-fold 14 days after estradiol-17 beta was administered. However, the hormone also elevated total RNA in the liver about 24-fold. Hence, the total ferritin mRNA content of the liver increased to about 8 times its initial amount. This pattern of gene expression was very similar to that for serum retinol binding protein. The estrogen induction of these two mRNAs appeared to parallel the overall stimulation of hepatic RNA synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1991

Molecular cloning of cDNA for the B beta subunit of Xenopus fibrinogen, the product of a coordinately-regulated gene family.

Fibrinogen, the principal blood-clotting protein, is made up of three different subunits synthesized in the liver. In vitro administration of glucocorticoids to liver cells from the frog Xenopus laevis causes a dramatic increase in fibrinogen synthesis. Investigations of molecular mechanisms underlying this hormonal stimulation at the mRNA level require cDNA clones complementary to the mRNAs coding for the three fibrinogen subunits, called A alpha, B beta, and gamma. We describe here the isolation and characterization of cDNA clones for the B beta subunit of Xenopus fibrinogen. cDNA libraries in both plasmid (pBR322) and phage (lambda gt10) cloning vectors were constructed from frog liver mRNA and screened with a rat B beta cDNA. Clones thus isolated hybridized to two Xenopus liver mRNAs 2500 and 1800 bases long, the previously-determined sizes for B beta mRNAs. The identity of the plasmid clone B beta-27 was confirmed by hybridization-selection of complementary mRNA which translated in vitro into the B beta polypeptide, as determined by size and susceptibility to thrombin cleavage. lambda/B beta 10, a clone representing nearly all of the 2500-base B beta mRNA, was isolated from the phage cDNA library. The 3'-end of this clone includes a polyadenylation signal about 20 residues upstream of a stretch of 34 adenosine residues, which probably represents the 3'-poly(A) tail of the messenger RNA. lambda/B beta 10 lacks only 20 nucleotides of full-length B beta mRNA at the 5'-end and there is one major start site of transcription. The 2500-base B beta mRNA has a 700-base extension at the 3'-end that is not present in the 1800-base mRNA. The Xenopus laevis genome contains two or three genes for the B beta fibrinogen subunit. Using the cDNA clone as a probe, B beta mRNA was shown to be induced at least 20-fold by glucocorticoid treatment of purified parenchymal cells of Xenopus liver maintained in primary culture.

Animals↗
PubMed1991

Identification of heterogeneity in human isolates of Giardia lamblia by isoenzyme studies.

Electrophoretic mobility patterns of six enzymes, viz. alkaline phosphatase E.C. 3.1.3.1., acid phosphatase E.C. 3.1.3.2., malic enzyme E.C. 1.1.1.40., phosphoglucomutase E.C. 2.7.5.1., isocitrate dehydrogenase E.C. 1.1.1.42., glucose-6-phosphate dehydrogenase E.C. 1.1.1.49 of two axenically cultured human Giardia lamblia isolated from India (PD-1 and PD-2) and one strain from Portland, Oregon, USA (P-1) were compared using polyacrylamide gel electrophoresis (PAGE). Based on the difference in the mobility patterns of the enzymes phosphoglucomutase, isocitrate dehydrogenase and malic enzyme, the PD-1 and PD-2 isolates appeared to be quite different from P-1. In the present study, the isocitrate dehydrogenase and alkaline phosphatase enzymes were used for the first time for differentiation of Giardia isolates. In the case of PD-1, two alkaline phosphatase bands could be seen whereas only one band was observed in PD-2 and P-1. Thus, the three strains could be grouped into three different zymodemes. These findings reveal the significant heterogeneity in G. lamblia isolates both from widely separated areas and within a single region. Heterogeneity among G. lamblia strains may explain the variable clinical manifestations, host response and treatment efficacy characteristic of human giardiasis.

Acid Phosphatase↗
PubMed1991

Effect of work load and respirator wear on postural stability, heart rate, and perceived exertion.

The effects on postural stability (sway) were investigated for different work loads under conditions of wearing a full facepiece respirator and not wearing any respiratory protection device. Fifteen subjects accomplished light (40 W), moderate (85 W), and heavy (125 W) work loads under the two conditions. Measurements of postural sway were made immediately after each load by using a multicomponent, strain gage-type force platform. Changes in each subject's movement pattern of the center of pressure were quantitated and compared to their initial baseline sway tests. Each subject's heart rate and perceived exertion were also recorded during each condition. A statistically significant effect (p = 0.007) caused by work load was observed for total length of sway with or without a respirator. An interaction approaching statistical significance (p = 0.056) between work load and respirator use was found. This indicated that sway increased more quickly and in a more consistently linear fashion with increasing work load under the respirator condition (p = 0.02) compared to the nonrespirator condition. The results from the respirator condition showed linear increases in postural sway length across the entire range of work loads, but sway length in the nonrespirator condition showed an increase only at 125-W work loads. The greater increase in sway during the postural balance test could be attributable to the increasing work load-induced proprioceptive fatigue effect on the nervous system's ability to process signals from proprioception systems incongruent with body sway. The heart rate was significantly higher during respirator wear (an increase in heart rate averaging 5.62 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

The role of a critical care unit in an epidemic.

The role of a critical care unit in life-threatening situations is well established. The management of 52 children with acute gastroenteritis and 22 children with acute paralytic poliomyelitis as part of recent epidemics is described. The solutions to the problems in the critical care management of these 74 victims (out of a total of 6197 patients admitted during the epidemics) are discussed.

Acute Disease↗
PubMed1991

Postural sway analysis of a teenager with childhood lead intoxication--a case study.

We had an opportunity to study a 15-year-old boy, evaluating the long-term effect of early childhood lead (Pb) poisoning on the maturation of postural balance. Postural balance (or sway) was quantified using a microprocessor-based Force Platform System along with four postural tasks specifically designed to indirectly challenge and/or minimize the effect of vision, proprioception and vestibular systems relevant for postural stability. The Pb-intoxicated patient showed increased postural sway compared to those of non-poisoned young adults and a 14-year-old boy for postural tasks requiring input from higher centers. A review of historical information and results of the physical and neurological examinations did not reveal an alternative explanation for this patient's postural sway abnormalities. These responses are also comparable to those noted in younger children with chronic Pb-exposure histories. In summary, this case study gives suggestive evidence that early excessive exposure to Pb can have long-term, detrimental neurological effects as reflected by postural stability. Measurement of postural balance appears to be a sensitive research methodology to assess subclinical neurological effects of remote lead intoxication.

Adolescent↗
PubMed1991

Coordinate regulation of fibrinogen subunit messenger RNA levels by glucocorticoids in primary cultures of Xenopus liver parenchymal cells.

Fibrinogen synthesis is specifically induced by a synthetic glucocorticoid, dexamethasone, in primary liver parenchymal cell cultures of the frog Xenopus laevis. Here we demonstrate that this increase in the level of fibrinogen protein production is accompanied by an induction in the three mRNAs coding for the fibrinogen subunits, designated A alpha, B beta, and gamma. The stimulation of fibrinogen mRNA levels appears to be mediated by the glucocorticoid receptor, because 1) the dose-response relationship parallels the reported affinity of dexamethasone for the Xenopus glucocorticoid receptor; and 2) the induction is blocked by RU 486, a potent antiglucocorticoid. All three subunit mRNA levels are induced coordinately by the hormone. The response is characterized by a detectable increase as early as 2-4 h after dexamethasone addition, continuing to a final 10- to 30-fold increase over basal levels by 60 h. The induction is specific for the fibrinogen mRNAs; total cellular RNA content and the levels of other mRNAs are unaffected by the hormone. Dexamethasone-mediated stimulation of A alpha and B beta mRNA production occurs in the absence of protein synthesis, whereas increased production of gamma mRNA is completely blocked under the same conditions. Thus, the A alpha and B beta genes are probably regulated at least in part by direct transcriptional activation by glucocorticoid-receptor complexes. Induction of the gamma gene is dependent on newly synthesized or labile proteins, which could be required for either transcription or posttranscriptional processes. These data suggest that different proteins are involved in regulation of the three fibrinogen genes.

Animals↗
PubMed1991

Breeding places of Phlebotomus argentipes Annandale and Brunetti (Diptera: Psychodidae) in West Bengal, India.

A search for the breeding places of Phlebotomus argentipes Annandale and Brunetti was undertaken in West Bengal during 1988-1990. Sugar flotation technique was applied for the isolation of larvae from the collected soil samples and emergence trap and sticky paper trap were used for the collection of adults. Soil incubation method was followed for the collection of emerged adults from the soil sample. A total 131 soil samples were analysed by flotation technique which produced 19 immature stages--7 from indoor and 12 from outdoor habitat. Soil incubation technique produced 38 adults of which 18 from indoor and 20 from outdoor. With the help of emergence trap 26 and 43 flies were collected from indoor and outdoor respectively. The number of immature stages and adult flies recovered from the outdoor showed higher recovery during post-monsoon months and lower in pre-monsoon and monsoon months. The result of this investigation indicated that probably the majority of the indoor catches are due to the migration of outdoor-produced sandflies specially in close surroundings where dried cow dung droppings were left. The necessity of spraying in these close areas in addition to indoor areas has been indicated to control the sandflies by antilarval measure.

Animals↗
PubMed1991

Metacyclogenesis of Leishmania spp: species-specific in vitro transformation, complement resistance, and cell surface carbohydrate and protein profiles.

Metacyclic (stationary) and logarithmic (log) forms of promastigotes of Leishmania donovani and Leishmania major were characterized in several ways. The highly active metacyclic forms were larger with more protein and less carbohydrate. The flagellum increased in length 2.4 times in L. major as compared to 1.8 times in L. donovani. Resistance to complement-mediated lysis by normal human serum of in vitro grown Leishmania promastigotes was related to the species, the growth phase in culture, and also the temperature. Metacyclic forms of both species had a much increased resistance to killing by normal serum at different temperatures. Differences in membrane-exposed carbohydrates were detected by fluorescein-conjugated lectins. Peanut agglutinin and Ulex agglutinin I differentiated log and stationary phase promastigotes of L. major. Higher amounts of acid phosphatase were demonstrated in the metacyclic phase. Differences in polypeptides were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two polypeptides of approximately 51 and 114 kDa were found exclusively in metacyclic promastigotes of both species, whereas 38- and 23-kDa polypeptides were lost or reduced during transformation from log to metacyclic phase promastigotes of L. donovani. In addition, a 75-kDa polypeptide was expressed only in metacyclic promastigotes of L. major.

Acid Phosphatase↗
PubMed1990

Isolation and characterization of cDNA clones for the gamma subunit of Xenopus fibrinogen, the product of a coordinately regulated gene family.

Fibrinogen, the major structural protein involved in blood coagulation, is synthesized and secreted by the liver. In the frog Xenopus laevis, fibrinogen production is dramatically induced by glucocorticoids. The hormonal stimulation requires synthesis of three separate subunits, designated A alpha, B beta, and gamma. For investigation of the molecular mechanisms underlying this coordinate induction, we have isolated cDNA clones for the subunits of Xenopus fibrinogen. In this communication we describe the identification of clones for the gamma chain. Initially, a Xenopus liver cDNA library in pBR322 was screened with a rat gamma chain cDNA and a clone representing half of the 1600-base frog gamma mRNA was identified. This clone was shown to be complementary to gamma mRNA by hybrid selection of mRNA that translated in vitro into the gamma polypeptide. A clone about 1460 base pairs in length was then isolated from a Xenopus liver lambda gt10 cDNA library and subcloned into Bluescript SK-. This clone, designated X1 gamma 3, contains the entire 3'-end and lacks 38 bases at the 5'-end of gamma mRNA. The deduced amino acid sequence at the N-terminal is compatible with a signal peptide of 20-23 amino acids, in agreement with the calculated size of the frog gamma chain signal peptide. Following the signal sequence is a region of highly conserved amino acids that participate in disulfide bond formation critical for the maintenance of tertiary structure in mammalian fibrinogen. The gamma cDNA clone was used to measure gamma mRNA in purified Xenopus liver cells treated with glucocorticoids in primary culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

Metabolic labeling of Entamoeba histolytica antigens: characterization of a 28-kDa major intracellular antigen.

The in vivo incorporation of radiolabeled amino acids into antigens of Entamoeba histolytica, HM-1:IMSS, is reported. Immunoprecipitation with sera from patients with invasive amebiasis revealed a 28-kDa antigen present in whole cell lysates of E. histolytica. This antigen was of cytoplasmic origin, as indicated by cell fractionation and Triton X-114 detergent-phase separation. Immunoprecipitation, using sera from patients with invasive amebiasis and symptomless cyst passers, revealed the 28-kDa antigen as the major antigen recognized by the sera tested. Immunoprecipitation analysis using radiolabeled-released proteins instead of whole cell lysates showed a number of bands, including the 28-kDa antigen. The data suggest that the 28-kDa antigen is of cytoplasmic origin or is released from the cytoplasmic compartment.

Amebiasis↗