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Biomedical subjects

D Hauser

Publications and source records attributed to D Hauser.

At least 19 recordsLinked to original sources
PubMed1992

Plasmid localization of a type E botulinal neurotoxin gene homologue in toxigenic Clostridium butyricum strains, and absence of this gene in non-toxigenic C. butyricum strains.

It has been shown recently that two Clostridium butyricum strains (ATCC 43181 and ATCC 43755) contain a botulinal neurotoxin type E (BoNT/E) gene closely related to that of C. botulinum type E. In this study, we show that this gene is located on a large plasmid in the two toxigenic C. butyricum strains and is absent in 18 non-toxigenic C. butyricum and C. beijerinckii strains. Interestingly, the 230 bp upstream and the 1260 bp downstream of the neurotoxin coding sequence are not present in either the non-toxigenic C. butyricum or C. beijerinckii strains. Our data suggest a BoNT/E gene transfer from C. botulinum E to originally non-toxigenic C. butyricum strains.

Base Sequence↗
PubMed1992

Sequences of the botulinal neurotoxin E derived from Clostridium botulinum type E (strain Beluga) and Clostridium butyricum (strains ATCC 43181 and ATCC 43755).

Recently, it has been shown that two Clostridium butyricum strains (ATCC 43181 and ATCC 43755), isolated from cases of infant botulism, produce a botulinal neurotoxin type E (BoNT/E). Here we have determined the nucleotide sequences of the BoNT/E genes of these two C. butyricum strains and from C. botulinum E strain Beluga. We show that the sequences of the BoNT/E genes from the two C. butyricum strains are identical and differ in only 64 positions resulting in 39 amino acid changes (97% identity at the amino acid level) from that derived from C. botulinum. Our data suggest a transfer of the BoNT/E gene from C. botulinum to the originally nontoxigenic C. butyricum strains.

Amino Acid Sequence↗
PubMed1991

Characterization of the C3 gene of Clostridium botulinum types C and D and its expression in Escherichia coli.

Clostridium botulinum type C and D strains produce exoenzyme C3, which ADP-ribosylates the Rho protein, a 21-kDa regulatory GTP-binding protein. In a previous work, we demonstrated that the C3 gene is encoded by bacteriophages C and D of C. botulinum by using DNA-DNA hybridizations with oligonucleotides deduced from the C3 protein N-terminal sequence. The C3 coding gene was cloned and sequenced, but its upstream DNA region could not be studied because of its instability in Escherichia coli. In this work, the upstream DNA region of the C3 gene was directly amplified by the polymerase chain reaction and sequenced. The C3 gene encodes a polypeptide of 251 amino acids (27,823 Da) consisting of a 40-amino-acid signal peptide and a mature protein of 211 amino acids (23,546 Da). The C3 mature protein was expressed in E. coli under the control of the trc promoter. The recombinant polypeptide obtained was recognized by C3 antibodies and ADP-ribosylated the Rho protein. The C3 gene nucleotide sequence is identical on C and D phage DNAs. At the amino acid sequence level, no similarity was found among C3, other ADP-ribosylating toxins, or tetanus or botulinal A, C1, and D neurotoxins.

Amino Acid Sequence↗
PubMed1991

Collection, processing and storage of peripheral blood stem cells (PBSC).

Eight patients with hematological malignancies were treated with autologous blood stem cell transplantation (ABSCT). Hemopoietic precursor cells were mobilized into the peripheral blood (PB) by chemotherapeutic induction of transient myelosuppression followed by an overshooting of blood stem cell concentration. PB CFU-GM showed a 15-20 fold increase on days 15-20 after chemotherapy. Peripheral blood stem cells were collected by 5-8 continuous flow leukaphereses using a Fenwall CS 3000 blood cell separator when platelet and WBC count was rising rapidly (platelet greater than 50 x 10e9/L and WBC greater than 1 x 10e9/L). Mean CFU-GM collected per run by leukapheresis were 10.85 x 10e4/Kg (procedure 3), 10.03 x 10e4/Kg (modified procedure 1). Mononuclear cell suspension in 10% DMSO was frozen at controlled rate freezer (-1 degree C to -4 degrees C) and stored in the liquid phase of nitrogen. After thawing CFU-GM recoveries ranged from 13.8% to 81.5%; 55-70% of recovered cells excluded trypan blue dye.

Adolescent↗
PubMed1989

Thinking aloud.

Explore the source record for details and available documents.

Humans↗
PubMed1988

Swine basal cell proliferation during a course of daily irradiation, five days a week for six weeks (6000 rad).

In swine skin irradiated with 200 rad per day, 5 days per week for 6 weeks, basal cell density remained at control levels for the first 2 weeks and then decreased to a nadir of 50% at 38 days. Thereafter it began increasing and returned to near control levels within 1 day after the end of irradiation on day forty-three. The mitotic index increased progressively to a maximum value three times the controls at day forty-two and then decreased as the cell density returned to control levels. The pattern strongly suggests that cell proliferation occurred during the period of irradiation. The cell density changes are simulated by a model in which doubling time switches from 12 days to 2.5 days at the 50% cell density level.

Animals↗
PubMed1986

Cryopreservation of human spermatozoa: correlations of ultrastructural sperm head configuration with sperm motility and ability to penetrate zona-free hamster ova.

Freezing and storage of human male gametes is associated with a reduction in the overall semen quality and establishment of pregnancy. This study was done to evaluate the integrity of sperm head ultrastructure (SHU) with computerized and vapor freezing. Comparisons were made between the effect of cryopreservatives glycerol (G) and dimethylsulfoxide (DMSO) on SHU. Twelve ejaculates from five proven fertile donors were studied with the use of routine semen analysis, zona-free hamster ova, and SHU. Both cooling processes, regardless of the preservative used, significantly reduced sperm function and the number of SH with intact plasma membranes. The staged cooling technique was substantially superior to vapor freezing in all parameters analyzed (P less than 0.01). G was less detrimental to the postthaw SHU than 1 M DMSO. A significant positive correlation (r = 0.98; P less than 0.01) was noted between the total number of intact SH and motile sperm. Computerized freezing in a G-diluted semen rendered a sperm environment that allowed the highest number of forms with intact SH membranes and with the best chances to penetrate zona-free hamster ova.

Animals↗
PubMed1974

Beta-adrenergic receptor: stereospecific interaction of iodinated beta-blocking agent with high affinity site.

An iodine-labeled beta-adrenergic inhibitor ((125)l-hydroxybenzylpindolol) binds specifically to a site on turkey erythrocyte membranes. A series of beta-adrenergic agonists and inhibitors compete for this binding site, with apparent affinities paralleling biological effectiveness as activators or inhibitors of catecholaminestimulated adenylate cyclase. The activity of d-(+) agonists or inhibitors was 1 percent (or less) than that of the corresponding l-(-) isomers in competing for binding of the iodinated blocker as well as in affecting catecholamine-stimulated adenylate cyclase. 1-(-)-Norepinephrine was about one-tenth as active as l-(-)-isoproterenol in competing for the beta-blocking agent site. The stereospecificity of the interaction with the iodinated beta-blocking agent and the correspondence between affinity for site and biological potency of analogs suggested that this interaction is involved in function of the beta-adrenergic receptor.

Adenylyl Cyclases↗