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Biomedical subjects

B Baker

Publications and source records attributed to B Baker.

At least 19 recordsLinked to original sources
PubMed1992

Structure-function relationship of myotoxin a using peptide fragments.

Myotoxin a, a small basic polypeptide isolated from the venom of prairie rattlesnake (Crotalus viridis viridis), has been shown to bind to sarcoplasmic reticulum (SR) Ca(2+)-ATPase. The attachment of myotoxin a to Ca(2+)-ATPase is believed to cause uncoupling of the calcium pump. In order to further elucidate which portion of myotoxin a is important for the uncoupling action, five peptides were synthesized and two peptide fragments were obtained by chemical cleavage. These peptides correspond to discrete portions of the primary sequence of myotoxin a. The peptides are equivalent to the primary sequence of myotoxin a from 1 to 16 residues, 7 to 22 residues, 13 to 28 residues, 19 to 34 residues, and 25 to 42 residues. Chemically produced fragments are equivalent to 1 to 28 residues and 29 to 42 residues of myotoxin a. Peptides of the sequences "YKQCHKKGGHCFPKEK" and "LGKMDCRWKWKCCKKGSG" of myotoxin a inhibited 45Ca uptake into isolated SR and bound to Ca(2+)-ATPase. The same peptides caused weak skeletal muscle vacuolization similar to that caused by native myotoxin a and increased serum creatine kinase activity. The active peptides correspond to the N-terminal and C-terminal portions of myotoxin a. The inactive or less active peptides have sequences which correspond to the middle sequence of myotoxin a. From this study, both the N-terminal and the C-terminal regions of primary sequence of myotoxin a are required to express myotoxin a's biological activity.

Amino Acid Sequence↗
PubMed1992

Medical management of inflammatory bowel disease in a spider monkey.

Inflammatory bowel disease was diagnosed in a 3-year-old, captive-born, hand-raised, female spider monkey (Ateles geoffroyi). The diagnosis was based on clinical signs, positive-contrast radiographic series, endoscopy, histologic appearance of intestinal biopsy specimens, and the monkey's response to treatment. Treatment consisted of oral administration of prednisone, sulfasalazine, and trimethoprim-sulfamethoxazole. Supportive care included a bland diet and an electrolyte solution given free choice. Although several infective agents were considered, this case illustrates that recurrent enteritis in primates may be noninfectious and may respond to anti-inflammatory agents.

Animals↗
PubMed1992

Expression of interferon-gamma receptors in normal and psoriatic skin.

Psoriatic keratinocytes have a reduced antiproliferative response to interferon (IFN)-gamma, and HLA-DR expression is usually not observed on keratinocytes in psoriatic plaques despite the presence of activated T cells. We have therefore compared the expression of IFN-gamma receptors in psoriatic skin with that of normal human skin. Using mouse monoclonal antibodies and immunoperoxidase staining on cryostat cut sections, we detected IFN-gamma receptors on keratinocytes throughout the epidermal layers except stratum corneum in normal skin (n = 11). Biopsy specimens from involved psoriatic skin (n = 17) consistently showed a staining pattern that differed from that of normal skin in that only the lower part of epidermis reacted with the antibodies to IFN-gamma receptors, whereas the upper layers showed no or minimal staining. Expression of IFN-gamma receptors in uninvolved psoriatic skin (n = 16) did not differ from that of healthy controls. Forty-five percent of the biopsies from lesional psoriatic skin displayed ICAM-1 positive keratinocytes, and only two specimens had a limited expression of HLA-DR reactive keratinocytes. The decreased binding of antibodies against the IFN-gamma receptors in the upper part of psoriatic epidermis might be secondary to abnormal maturation of psoriatic keratinocytes or a primary defect involving abnormal modulation of IFN-gamma receptors.

Adult↗
PubMed1991

Binding of myotoxin a to sarcoplasmic reticulum Ca(2+)-ATPase: a structural study.

The interaction of myotoxin alpha with intact sarcoplasmic reticulum (SR) components was investigated, and two SR proteins were identified that associated with myotoxin a. One of the proteins has an apparent molecular weight similar to the Ca(2+)-ATPase, the major SR protein responsible for calcium loading. Ca(2+)-ATPase was purified, and its interaction with myotoxin a was studied. Evidence for specific binding of myotoxin a to Ca(2+)-ATPase was established by isolating chemically cross-linked myotoxin a-Ca(2+)-ATPase complexes and further proving their association with anti-myotoxin a antibodies. The binding region of myotoxin a was further delineated by cleaving the protein with cyanogen bromide (CNBr) into two fragments, a larger N-terminal fragment of 28 residues and a smaller C-terminal fragment of 14 residues. Competition experiments with 125I-myotoxin a showed that the C-terminal fragment competed better against 125I-myotoxin a than the N-terminal fragment for SR protein binding. Two overlapping peptides covering the sequence of the N-terminal fragment were synthesized to clarify the interaction of the N-terminal fragment of myotoxin a with SR proteins. A 16-residue peptide corresponding to residues 1-16 competed strongly with 125I-myotoxin a, while a second peptide (residues 13-28) did not.

Amino Acid Sequence↗
PubMed1991

Ac transposition from a T-DNA can generate linked and unlinked clusters of insertions in the tomato genome.

We have investigated the distribution of transposed Acs in the tomato genome. Our approach has been to clone the regions flanking the T-DNAs and transposed Acs from two transgenic lines of tomato and place these sequences on the tomato restriction fragment length polymorphism (RFLP) map. The distribution of transposed Acs around the T-DNA and at locations unlinked to the T-DNA indicates that Ac transposes to linked and unlinked sites in tomato as it does in maize. The structure and terminal sequence of these cloned elements shows that Ac remains intact after transposition. We discuss these results and their bearing on gene tagging strategies using Ac and Ds.

Base Sequence↗
PubMed1991

Psychiatric treatment strategies for patients at risk of dying suddenly.

This paper outlines the development of psychiatric treatment approaches to certain patients with life-threatening ventricular arrhythmias which may affect outcome, both psychological and, at times, medical. Three cases sketches which illustrate psychiatric management strategies are presented. One case history indicates how lack of adherence to such treatment contributed to a negative outcome. Emphasis is placed on an integrated approach to psychiatric treatment which is individualized for each patient. The importance of close liaison with cardiologist, selective psychotherapy, stress management skills and family involvement is highlighted.

Adaptation, Psychological↗
PubMed1991

Detection of hepatitis C viral RNA in serum of a patient with acute non A, non B hepatitis.

The sequence of serologic events in a patient with acute type C hepatitis associated with intravenous drug abuse is described. Hepatitis C virus (HCV) ribonucleic acid was detectable in serum during the acute episode of hepatitis, whereas antibody to the hepatitis C virus appeared later, after the acute illness had subsided. The patient developed chronic hepatitis with persistently elevated serum aminotransferase activities. Both hepatitis C viral ribonucleic acid and antibody to hepatitis C virus persisted in serum, together with elevated serum aminotransferases. Thus, detection of HCV RNA may be useful in the diagnosis of acute type C hepatitis, particularly in the absence of detectable antibody to the hepatitis C virus.

Acute Disease↗
PubMed1978

Characteristics of cellular RNA related to the transforming gene of avian sarcoma viruses.

Nucleotide sequences (sarc) related to the transforming gene of avian sarcoma viruses are present in the DNA and transcribed into RNA in uninfected avian cells (Stehelin et al., 1976b; Spector et al., 1978). Cytoplasmic RNA containing the sarc sequences has a sedimentation coefficient of 30S, is linked to polyadenylic acid and is present in polyribosomes in a form which can be released by treatment with EDTA. Hence the sarc sequences (complexity = 5 x 10(5) daltons) are part of a larger transcriptional unit (approximately 1.8 x 10(6) daltons), and the sarc RNA appears to serve an as yet unknown messenger function. In addition, the sarc sequences in chicken cells are not linked to RNA transcribed from the provisrus of the endogenous virus RAV-O, since RAV-O cytoplasmic RNA has sedimentation coefficients of 32S and 21S. Comparison of sarc-containing RNA in quail embryo fibroblasts and in quail cells derived from a methylcholanthrene-induced fibrosarcoma revealed no differences with respect to size, polyadenylation or concentration of the RNA in nuclei, cytoplasm and polyribosomes; thus the phenotypic differences between these cells are unlikely to be a consequence of alteration in expression of the sarc sequences.

Alpharetrovirus↗
PubMed1978

Genesis of a virus-transforming gene.

The gene src responsible for neoplastic transformation of fibroblasts by avian sarcoma viruses was apparently derived from highly conserved nucleotide sequences in the normal avian genome. The cellular homologue of src is unlinked to the genome of an endogenous virus in chicken cells and functions in an unknown manner during normal cell metabolism.

Alpharetrovirus↗
PubMed1978

Computerized controlled drug inventory system.

The development and use of a computerized system for controlled drug inventory is described. The system configuration, processing and report programs are discussed. The system is capable of producing reports on controlled drug prescriptions and receipts, current balances, and close-out inventory levels, as well as patient use and physician screens. This flexible system, developed with limited hardware, has the ability to provide up-to-the-minute accounting of controlled drugs.

Computers↗
PubMed1978

Trans-delta-9-tetrahydrocannabinol: effects on macromolecular content of mouse liver tissue.

Mice were starved for 72 hours then injected with a total of 50 mg/kg THC over 48 hours during which time the animals were fed ad libitum. At the end of the 48 hours, the mice were sacrificed and the livers were analyzed quantitatively for DNA, RNA, protein, and glycogen. It was determined that the THC had no effect on the DNA or glycogen levels. The amount of RNA increased significantly when compared to controls while protein levels decreased by 50%.

Animals↗
PubMed1977

An electron microscopic and enzymic study of rat liver peroxisomal nucleoid core and its association with urate oxidase.

The appearance of the characteristic crystalloid core of rat liver peroxisomes is emulated by the electron microscopic (EM) appearance of highly purified urate oxidase prepared from the same tissue. The purity of the enzyme preparation was established by gel electrophoresis under various conditions and the specific enzyme activity was at least as high as any previously reported. The amino acid composition of urate oxidase was determined. As additional evidence for close association of the peroxisomal core with urate oxidase, it was demonstrated that the biphasic changes in rat liver urate oxidase activity in response to prolonged starvation were paralleled by changes in the EM appearance of peroxisomes. Under comparable conditions catalase, another peroxisomal enzyme, did not show the same changes in activity as did urate oxidase. Evidence for the possible identity of urate oxidase with the peroxisomal crystalloid of rat liver has been presented, all materials having been obtained from, and experiments performed with, the rat.

Amino Acids↗