Biomedical subjects
Publications and source records attributed to S Bhaduri.
Staphylococcus aureus S-6 cells grown in chemically defined media often lysed after exponential growth. Lysis could be prevented by the addition of alanine or proline before the culture reached stationary phase.
A simple and rapid method was developed for the extraction of proteins from both pathogenic and nonpathogenic bacteria. The method involves the treatment of cells with acetone followed by sodium dodecyl sulfate extraction of cellular proteins. Polyacrylamide gel electrophoresis revealed that the protein composition of extracts made by this method was comparable to that of extracts made by established methods, namely, sonication and agitation with beads. This technique has been successfully applied to the extraction of proteins from a wide variety of bacteria, including pathogens.
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In a retrospective study, total antimicrobial decontamination with strict reverse isolation (ITD) and selective decontamination without isolation (SD) were compared as means of preventing infection in patients with acute leukaemia. Thirty patients were treated with ITD and 34 patients with SD. The surveillance cultures indicated that aerobic gram-negative bacilli and yeast could be equally eliminated effectively in both the groups. The anaerobic flora was only minimally influenced by SD. The incidence of acquired infections was 1.17 per patient in group ITD as compared to 0.85 in group SD. In group ITD, acquired bacterial infections were mostly caused by gram-negative bacilli (63%) whereas in the group SD these microorganisms accounted only for 25% of the infections. In group SD the total number of fever days was significantly lower and the mean duration of pyrexial episodes was substantially shorter. The results indicate that SD is an effective and inexpensive method for preventing gram-negative infections and might be at least as effective as ITD.
The pathogenicity of microorganisms isolated by surveillance cultures, the neutrophil count in the peripheral blood, and the interaction of the two factors were analyzed as risk factors for infections of the oropharynx and the respiratory tract in patients with acute leukemia being treated in strict reverse isolation under antimicrobial modulation. A statistical method was developed for the identification of bacteria, the presence of which was correlated with an increased risk of infection. A significantly increased risk was found mainly for species of Klebsiella, Enterobacter, Proteus, and Pseudomonas. The degree of neutropenia was significantly correlated with the risk of infection, which was influenced by the microbiologic state of the oropharynx. Thus, patients with gram negative bacilli had significantly more days with infection at all levels of neutropenia than patients without gram-negative bacilli. These two risks factors were additive but did not potentiate each other.
The in vitro function of granulocytes collected by filtration leukapheresis after premedication of donors with dexamethasone was found to be normal. In vivo studies were performed in a 21-year-old woman who was transplanted with allogeneic bone marrow for severe aplastic anaemia. The patient received granulocyte transfusions for treatment of septicaemia during the transplantation period. On 11 consecutive days an average dose of 7.2 X 10(10) granulocytes/transplantation, the patient died from cardiac failure. Transfused granulocytes were found ante mortem in a pericardial effusion and post mortem in lungs, kidneys, liver and spleen. The data indicate that filter collected granulocytes function normally in the recipient and are clinically effective.
40 patients with acute leukaemia and severe granulocytopenia were treated with granulocyte transfusions for bacteriologically documented or clinically suspected septicaemia. The patients received an average of 5 transfusions each with 2.1 X 10(10) granulocytes per m2 body surface area per day. 26 patients showed clinical benefit from transfusion therapy as documented by the course of blood cultures, local lesions and fever. Only patients with regeneration of granulopoiesis had definite benefit from granulocyte transfusions. All other patients died ultimately from septicaemia.
Early region 2 (E2) of the adenovirus 2 genome specifies a 72,000-dalton DNA-binding protein that is required for viral DNA replication. Electron microscopy studies have detected two major forms of 20S E2 mRNA, one species with a 5' leader from map position 75 and a second form having a leader from position 72 (Chow et al., J. Mol. Biol. 134:265-303, 1979). Only the species with a leader from position 75 was detected at early times; however, both forms were found at late times. We have analyzed the temporal regulation of E2 expression by documenting mRNA accumulation in the cytoplasm. Kinetic studies of pulse-labeled RNAs demonstrated a peak of E2 cytoplasmic RNa synthesis at 10 to 12 h, coinciding with the time of maximal synthesis of the 72,000-dalton DNA binding protein and viral DNA. To estimate the relative abundances of the two major E2 RNA species at various times during infection, total E2 cytoplasmic and polysomal 20S RNAs were isolated by hybridization-selection with specific DNA probes. The leader sequences in the selected RNAs were then quantitated by further RNA-DNA hybridization. We found that the elevated accumulation rate for E2 cytoplasmic RNA at late times reflected an increase in formation of both major species. Moreover, for all time points examined 66% of the mRNA species had a 5' end from map position 75, and 33% had a 5' terminus from position 72. Continuous labeling experiments provided evidence that both RNA forms have comparable half-lives. The results suggest that the two major species encoded by E2 are regulated in a coordinate fashion late in infection.
The efficiency of strict reverse isolation and antimicrobial decontamination in remission induction therapy of acute leukemia was studied retrospectively in 47 patients who were treated with a standardized aggressive chemotherapy of daunorubicin and cytosine arabinoside. Twenty-two patients were treated in strict reverse isolation with antimicrobial decontamination and 25 patients in the open ward without any measures against infections. In the patients in isolation the incidence of new infections per patient was 0.77 compared to 1.42 in the control group. The rate of complete remissions was 77% in the patients in isolation vs. 56% in the control patients.
A plasmid containing the entire Salmonella typhimurium his operon was constructed from plasmid pM89 and an EcoRI fragment of phi 80 his imm lambda DNA. The recombinant pST41 also includes the glucose 6-phosphate dehydrogenase (gnd) gene and has one EcoRI endonuclease cleavage site in the integrated fragment. This plasmid served as a source for the construction of two additional plasmids, one carrying the OGDC-region of the his operon and the other a CBHAFIE segment of the his gene along with the gnd gene. The presence of the his operon in the constructed plasmids was confirmed by hybridization to S. typhimurium his RNA. The location of the gnd gene in the CBHAFIE fragment of the his gene was confirmed genetically: after transfection with the plasmid bearing the gnd gene, a gnd recipient gained the capacity to utilize gluconate as a sole carbon source. The DNAs of the three hybrid plasmids were analyzed by gel electrophoresis. By comparing the EcoRI endonuclease cleavage pattern of these three hybrid plasmids with the DNA cleavage pattern of phi 80 his imm lambda, phi 80 imm lambda and lambda phages, the EcoRI cleavage map of phi 80 his imm lambda was obtained.
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A 3-year-old boy (patient A) with a congenital and a 24-year-old man (patient B) with an acquired granulocyte function defect received supportive granulocyte transfusions for the management of severe infections. The boy had suffered from recurrent infections since bith. His granulocytes showed in vitro almost no chemotactic responsiveness, an impaired phagocytosis and reduced intracellular killing of Candida albicans. Family studies suggested that it was an inherited autosomal recessive defect. The child developed a Pseudomonas pneumonia at the age of 3 years, which did not respond to antibiotic therapy. Granulocyte transfusions were then started and soon after the fever and pneumonia disappeared. Patient B showed the haematological signs of a preleukaemic state. He had 3 recurrent episodes of furunculosis which led each time to cellulitis and septic temperatures accompanied by symptoms of an enterocolitis. Tests of granulocyte function in vitro showed reduced intracellular killing of Staphylococcus aureus. Granulocyte transfusions were started, since no clinical improvement could be attained by antibiotics. With transfusion therapy, fever, cellulitis and enterocolitis disappeared each time.
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The DNA binding proteins in a nuclear membrane fraction that can synthesize DNA in vitro (referred to as "nuclear membrane complex") and in the cytoplasm of adenovirus infected and uninfected cells were isolated and characterized. Suspension cultures of human KB cells infected with human adenovirus 2 were treated with 25 mu-g/ml of arabinosylcytosine starting at 2 hr to block the synthesis of viral structural proteins, and then labeled with (3H)leucine from 6 to 24 hr after infection. Uninfected cells were treated similarly and labeled with (14C)leucine. The 3H-labeled proteins (infected cells) and 14C-labeled proteins (uninfected cells) isolated from the cytoplasm were mixed, as were the corresponding proteins isolated from the membrane complex, and each mixture was fractionated by stepwise elution from single-stranded DNA-cellulose columns. From 50 to 60% of the labeled protein in the membrane complex from infected cells and 40 to 50% of that from uninfected cells bound to DNA-cellulose in 0.05 M NaCl. Much less protein from the cytoplasm was bound to DNA cellulose, 20% from infected cells and 11% from uninfected cells. Gel electrophoresis of the mixture of 3H- and 14C-labeled proteins eluted from DNA-cellulose by different concentrations of NaCl revealed the following. (1) The 0.15 and 0.40 M NaCl eluates from the membrane complex of infected and uninfected cells contained a heterogenous mixture of similar polypeptides. (2) The 0.6 M NaCl eluate from the membrane complex derived from infected cells contained two major DNA binding proteins with molecular weights of 75,000 and 45,000 that were absent from uninfected cells. Large quantities of these two proteins were present in highly purified form in the 0.6 M NaCl eluate from the cytoplasm of infected cells. The DNA binding proteins of molecular weight 75,000 and 45,000 that are present in the cytoplasm are identical with those present in the membrane complex, as established by coelectrophoresis. (3) Two major cell-specific proteins of molecular weight 40,000 and 15,000-17,000 were present in the 2 M NaCl eluate of the membrane complex from uninfected and infected cells. A major cell-specific protein of molecular weight 33,000 was present in the 0.15 and 0.4 M NaCl eluates of the uninfected and infected cell cytoplasmic fractions. Aanalysis of cells labeled at 2-6 hr after infection in the absence of arabinosyl cytosine indicated that the synthesis of the DNA binding proteins of molecular weight 75,000 and 45,000 begins early after infection prior to the onset of viral DNA replication.
We have investigated three aspects of RNA turmor virus replication and cell transformation: (1) the properties of the purified avian and mammalian viral RNA-directed DNA polumerase, (2) some characteristics of the viral 60-70S RNA genome, 30-40S RNA subunits and intracellular viral RNA species, and (3) the interaction of the viral DNA polymerase with its RNA template early during infection and cell transformation by the murine sarcoma-leukemia virus (MSV[MLV]). Avian myeloblastosis virus (AMV) contains two forms of RNA-directed DNA polymerase, alpha, consisting of a single polypeptide of molecular weight 65,000, and alphabeta, consisting of two polypeptides of molecular weights 65,000 and 105,000. The alpha and alphabeta forms of AMV DNA polymerase both possess RNase H activity that requires free end termini on the ribopolymer and can degrade the RNA of the RNA-DNA hybrid in the 3' to 5' and 5' to 3' directions. But, alpha and alphabeta possess a different mode of exoribonuclease activity. While alphabeta RNase H is a processive exoribonuclease that degrades the polynucleotide chain to a core residue before attacking a second chain, alpha RNase H is a random exoribonuclease that releases the polynucleotide after each scission. Highly purified Moloney-MSV(MLV) DNA polymerase has both RNase H activity and the ability to read viral 60-70S RNA. These activities comigrate through five different steps of purification and are present at levels comparable to those found in purified AMV DNA polymerase. The MSV(MLV) 60-70S RNA genome and 35S RNA subunits were shown by periodate oxidationtritiated borohydride reduction to contain adenosine as the major 3'-terminal nucleoside. Poly (A) segments were isolated from viral 60-70S and 35S RNA by treatment with RNase A or RNase T1 and purified by afinity chromatography and gel electrophoresis. Viral poly(A) was shown to be present at the 3' terminus as -G(C,U)A190AOH. The similar sequence reported for poly(A) present in mammalian mRNA suggests that similar mechanisma are involved in the transcription and processing of both cellular and viral DNA sequences. Within transformed cells replicating MSV(MLV), viral 35S and 20S RNA were found in membrane-bound polyribosomes, whereas only 35S RNA was detected in free polyribosomes. The origin and function of 20S RNA is unknown. The early events during rapid infection and cell transformation of mouse 3T6 cells by the Harvey strain of MSV(MLV) were studied. By both autoradiographic analysis and molecular hybridization, viral DNA synthesis was detected in the cytoplasm by 1 hour after infection, reached a maximum at 2 hours, and subsequently decreased. Cytological chase experiments produced evidence that cytoplasmic viral DNA was transported to the nucleus. In situ hybridization experiments using radioactive viral DNA product as a probe demonstrated the rapid association of viral DNA sequences with the chromocenters of interphase nuclei and with the centromeric heterochromatin regions of some chromosomes.
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