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Biomedical subjects

J Cook

Publications and source records attributed to J Cook.

At least 55 records · Page 3Linked to original sources
PubMed1988

Evaluation of staining methods for identifying Campylobacter pylori.

Campylobacter pylori has been implicated in the pathogenesis of peptide ulcer disease. The rapid identification of this organism may depend upon histologic diagnosis, because culture methods are complex and require a minimum of seven days in order to identify a negative specimen. The purpose of this study was to determine which stain used to identify this organism was the most cost-effective and easiest to perform and interpret on a routine basis. Sixty-one consecutive gastric antral biopsies were stained with hematoxylin and eosin, Giemsa, Brown-Brenn, and Warthin-Starry, with 23 of the cases stained by Brown-Hopps. Of the stains tested, the Wright-Giemsa was the easiest to perform. The organisms on the Wright-Giemsa showed a smooth, uniform purple color, whereas the Warthin-Starry gave the organism a granular appearance that at times could be confused for silver precipitate. Both the Wright-Giemsa and Brown-Hopps stain had the highest degree of identification of the organism (defined by percent positivity). The routine use of the Wright-Giemsa stain for identification of C. pylori in antral biopsies is recommended.

Acute Disease↗
PubMed1987

Ovomucoid third domains from 100 avian species: isolation, sequences, and hypervariability of enzyme-inhibitor contact residues.

Ovomucoids were isolated from egg whites of 100 avian species and subjected to limited proteolysis. From each an intact, connecting peptide extended third domain was isolated and purified. These were entirely sequenced by single, continuous runs in a sequencer. Of the 106 sequences we report (five polymorphisms and chicken from the preceding paper [Kato, I., Schrode, J., Kohr, W. J., & Laskowski, M., Jr. (1986) Biochemistry (preceding paper in this issue)]), 65 are unique. In all cases except ostrich (which has Ser45), the third domains are either partially or fully glycosylated at Asn45. The majority of the third domain preparations we isolated are carbohydrate-free. Alignment of the sequences shows that their structurally important residues are strongly conserved. On the other hand, those residues that are in contact with the enzyme in turkey ovomucoid third domain complex with Streptomyces griseus proteinase B [Read, R., Fujinaga, M., Sielecki, A. R., & James, M. N. G. (1983) Biochemistry 22, 4420-4433] are not conserved but instead are by far the most variable residues in the molecule. These findings suggest that ovomucoid third domains may be an exception to the widely accepted generalization that in protein evolution the functionally important residues are strongly conserved. Complete proof will require better understanding of the physiological function of ovomucoid third domains. This large set of variants differing from each other in the enzyme-inhibitor contact area and augmented by several high-resolution structure determinations is useful for the study of our sequence to reactivity (inhibitory activity) algorithm. It is also useful for the study of several other protein properties. In the connecting peptide fragment most phasianoid birds have the dipeptide Val4-Ser5, which is absent in most other orders. This dipeptide is often present in only 70-95% of the molecules and appears to arise from ambiguous excision at the 5' end of the F intron of ovomucoid. Connecting peptides from the ovomucoids of cracid birds contain the analogous Val4-Asn5 peptide. In laughing kookaburra ovomucoid third domain we found (in 91% of the molecules) Gln5A, which we interpret as arising from ambiguous intron excision at the 3' end of the F intron.

Amino Acid Sequence↗
PubMed1987

The impact of physical fitness and health-age appraisal upon exercise intentions and behavior.

This study investigated the relative and combined effectiveness of the Canadian Home Fitness Test (CHFT) and Health Hazard Appraisal (HHA) to modify (1) intention to exercise with and without knowledge of the results and (2) intention and behavior to exercise over 3 months. The 200 subjects were randomly attributed to groups, either (1) physical-fitness evaluation (PF), (2) appraised health age (HA), (3) physical-fitness evaluation and health-hazard appraisal (PF-HA), or (4) control (C). The immediate impact on the intention to exercise of passing one and/or the other tests, without knowledge of the results, was not significant. With knowledge of the results, the intentions of the PF and PF-HA groups differed from those of the C group. This effect disappeared after 3 months. There was no significant impact on exercise behavior over 3 months. The results indicated a short-term motivational effect from being informed of CHFT results. Maintaining this effect might require intervention on a long-term basis.

Adult↗
PubMed1987

Flow cytometric analysis of intracellular pH in 3T3 cells.

Techniques to determine intracellular pH generally report the average pH of population and do not indicate whether or not there is significant variance among cells within the population. Population variance is important to ascribe pH changes on a per cell basis. The magnitude of the pH change in individual cells is important to ascribe physiological function to changes in pH. To determine the variability of cell responses, we have used dual wavelength fluorescence emission spectroscopy of intracellular dicyanohydroquinone monitored with flow cytometry to determine the pH of normal and transformed 3T3 cells in response to serum or serum components. All cells were mechanically harvested from subconfluent cultures. Large differences in pH were observed between serum-deprived and serum-conditioned normal, but not transformed, cells. Addition of serum caused cytosolic alkalinization, with the serum-deprived cells responding more slowly. Titration of cells with submaximal doses of serum indicate that the response of pH is graded, that all cells respond in similar manner, and that the relative affinity of transformed cells for the serum components causing the pH effect is about twice that of normal cells.

Animals↗
PubMed1987

Comparison of the antioxidant properties of alpha-tocopherol and alpha-tocopheryl acetate in newborn rabbit lung.

The antioxidant properties of alpha-tocopherol and alpha-tocopheryl acetate in lung tissue were quantitated in vitro by measurement of thiobarbituric acid (TBA) reactants, pentane production and lipid peroxides following either an iron/ascorbate or a xanthine/xanthine oxidase oxidant stress. Lung homogenates were obtained from newborn rabbits treated intravenously with either 10 or 100 mg/kg of either alpha-tocopherol or alpha-tocopheryl acetate. The animals were killed 5 min after dosing to minimize the conversion of alpha-tocopheryl acetate to alpha-tocopherol. Lung homogenates from animals treated with alpha-tocopherol had decreased concentrations of TBA reactants and pentane production after incubation with either oxidant stress compared to lung homogenate from animals treated with alpha-tocopheryl acetate or vehicle alone. Lipid peroxide concentrations were no different in homogenates from alpha-tocopherol or alpha-tocopheryl acetate treated animals. Correlations between antioxidant activity and tissue concentrations of alpha-tocopherol indicate 50% inhibition is achieved with 30-100 micrograms/g lung tissue. In vitro addition of alpha-tocopherol required concentrations between 100 and 200 micrograms/g to reduce lipid peroxidation by 50%.

Animals↗
PubMed1987

Zinc deficiency and immune function.

Deficiency in zinc, an essential trace element, is a frequent human dietary problem in the United States and is also associated with such disease states as alcoholism, renal disease, burns, gastrointestinal tract disorders, and acrodermatitis enteropathica. Skin lesions and poor wound healing are observed in severe forms of the deficiency. However, modest deficits in zinc cause lymphopenia and reduced immune capacity among affected humans. With the mouse used as a model because it has an immune system analogues to that of humans, the effects of zinc deficiency on immune function have been well characterized. A suboptimal intake of zinc causes marked atrophy of the thymus, a 50% reduction in leukocytes, a rise in corticosterone levels, and a 40% to 70% reduction in antibody-mediated, cell-mediated, and delayed-type hypersensitivity responses.

Animals↗
PubMed1987

Interleukin-2 and coculture with thymic epithelial cells synergistically induce prothymocyte differentiation and proliferation.

T cell precursors or prothymocytes present in the spleen and bone marrow of mice lack the differentiation antigens found on mature thymocytes. Incubation of prothymocytes with the hormone products of thymic epithelial cells can trigger induction of antigens like Thy 1.2. We have recently found that interleukin-2 will also induce Thy 1.2. We have found that a 4 day incubation of prothymocytes (derived from the spleens of nu/nu mice) with natural and recombinant interleukin-2 in the presence of human thymic epithelial cells results in their synergistic effect on prothymocyte differentiation as measured by Thy 1.2 induction using a fluorescence activated cell sorter (FACS). This coculture condition also caused a synergistic enhancement of proliferation of the prothymocytes and the appearance of a population of large lymphoblasts. Analysis of the presence of Thy 1.2 surface antigen indicated that induction of this surface antigen occurs on both medium sized and large lymphoblast populations. Under these conditions induction of Ly 2 surface antigen was not detected and prothymocytes at the end of the coculture did not manifest IL-1 or mitogen responsiveness. Incubation of prothymocytes in the presence of thymic epithelial cells alone resulted in a lesser degree of Thy 1.2 induction and proliferation and in the consistent induction of low levels of interleukin-2 (0.5-1 unit/ml). Thymosin fraction V did not have a synergistic effect with IL-2 on the cell proliferation. The enhanced response of prothymocytes to IL-2 in the presence of thymic epithelial cells presumably results from the enhanced induction of IL-2 receptors and/or responsiveness. The observation offers further support for a role of interleukin-2 in the regulation of T cell ontogeny.

Animals↗
PubMed1986

Discriminative and aversive properties of beta-carboline-3-carboxylic acid ethyl ester, a benzodiazepine receptor inverse agonist, in rhesus monkeys.

Rhesus monkeys were trained to discriminate injections of saline from those of beta-carboline-3-carboxylic acid ethyl ester (beta-CCE), a compound that binds to the benzodiazepine receptor, but often has actions opposite to those of the benzodiazepines. A benzodiazepine agonist midazolam and low doses of a specific benzodiazepine antagonist, Ro 15-1788, reversed the discriminative effects of beta-CCE. Higher doses of Ro 15-1788 produced stimulus effects similar to beta-CCE. In a separate experiment, monkeys responded to terminate intravenous infusions of beta-CCE, but not midazolam. This aversive effect of beta-CCE was reversed by Ro 15-1788. The behavioral effects of beta-CCE in these non-human primates are consistent with other data that have shown it to act on benzodiazepine receptors, and support the hypothesis that beta-CCE can be considered an inverse agonist at this receptor.

Animals↗
PubMed1986

Characterization of the human glomerular C3 receptor as the C3b/C4b complement type one (CR1) receptor.

The functional and immunochemical characteristics of the human glomerular C3 receptor were investigated by adherence of sheep erythrocytes (Es) coated with defined C3 fragments and by using polyclonal and/or monoclonal antibodies directed against epitopes expressed on complement receptors CR1, CR2, and CR3. C3b-bearing Es (EsC3b) strongly adhered to glomeruli in frozen kidney sections in a reaction that was selectively inhibited by F(ab')2 anti-CR1 antibodies. There was no adherence of EsC3dg, EsC3d, and EsC3bi in the presence or absence of Ca++ and Mg++ under physiologic buffer conditions. The weak glomerular binding of EsC3bi, which was observed in half-isotonic buffer was selectively suppressed by anti-CR1 antibodies. By indirect immunofluorescence, anti-CR1 antibodies stained all podocytes in glomeruli, whereas no staining of kidney sections was seen with OKM1 and anti-Mol antibodies directed against the alpha-chain of CR3 and with anti-CR2 antibodies anti-B2 and BL13. Solubilization of membrane glycoproteins from freshly isolated glomeruli from three human kidneys, in the presence of 0.1% Nonidet P-40, yielded a material that bound to lentil lectin Sepharose and could accelerate the decay of preformed cell-bound amplification C3 convertase sites in a reaction that was inhibited by anti-CR1 antibodies. The material containing CR1 activity was labeled with 125I, immunoprecipitated with anti-CR1, and analyzed by SDS-PAGE and autoradiography. Anti-CR1 immunoprecipitated a form of CR1 of Mr 205,000 in solubilized glomeruli from three donors, and an additional form of Mr 160,000 in glomeruli from two of the donors. Immunoprecipitation of CR1 from surface-labeled erythrocytes from these individuals demonstrated them to be homozygous for the 205,000 Mr form of the receptor. Whether the 160,000 band represents in vitro or in vivo proteolytic cleavage of CR1, or cell specific-modulation of gene expression of glomerular CR1, remains unclear. Thus, CR1 is the only type of C3 receptor expressed in the human kidney. Glomerular CR1 shares the functional antigenic and biochemical properties of the C3b/C4b CR1 receptor of peripheral blood cells.

Animals↗
PubMed1986

15-HETE "modulates" expression of C3b receptor (CR1) antigen on peripheral blood B-lymphocytes.

We have studied the effect of the lipoxygenase metabolite, 15-HETE, on the expression of the human C3b receptor (CR1) by a B-lymphocyte enriched population of human peripheral blood leukocytes. The number of CR1 antigenic sites expressed by B-lymphocytes isolated from HLA typed donors was determined by equilibrium binding studies using an 125 I-labelled mouse monoclonal anti CR1 antibody before and after 16 hrs incubation in RPMI alone or containing 10(-6)M, 10(-7)M or 10(-8)M final concentration of 15-HETE. In B44- subjects CR1 expression on B cells increased 63% after incubation in RPMI alone. This increase was inhibited in the presence of 10(-6)M and 10(-7)M 15-HETE (23% and 30% increase respectively). In contrast, B44+ individuals showed a smaller increase in CR1 numbers when incubated in RPMI alone. In the presence of 15-HETE CR1 antigenic sites continued to increase. When B44+ subjects were classified as A29+ or A29-, donors that were A29+ B44+ accounted for the augmentation observed while A29- B44+ individuals did not differ from individuals that were A29- B44-.

Antigens, Surface↗
PubMed1986

Acute parathyroid hormone secretory dynamics: hormone secretion from normal primate and adenomatous human tissue in response to changes in extracellular calcium concentration.

PTH secretion has been evaluated extensively using short term incubation techniques, but these methods cannot be used to adequately evaluate the early phases of PTH secretion. We developed a dispersed cell perifusion system to study these acute secretory events. Responses to low calcium conditions were studied using dispersed cells from normal primate and adenomatous human parathyroid tissue. When these cell were perifused with 1.0 mM calcium medium, PTH secretion was stable, but increased within minutes in a dose-dependent manner in response to a lowering of extracellular calcium concentrations. Similarly, PTH secretion quickly declined when cells were exposed to higher extracellular calcium concentrations. In studies of cells from 11 human adenomas, the mean maximum secretion in response to 0.25 mM calcium conditions was 587 +/- 330% (+/- SD) of that in response to 1.0 mM calcium. The magnitude of the response to low calcium stimulation was variable, and cells from two additional adenomas failed to respond to low calcium stimulation despite responses to other secretogogues. Variation in the rate of increase in stimulated PTH secretion was also found among the adenomas examined (128 +/- 95% of baseline/min), and the rate of increase in PTH release and the eventual maximum rate of release were positively correlated. In studies of cells from 4 normal primates (rhesus macaque), the maximum response to 0.25 mM Ca2+ (544 +/- 118% of baseline) and the rate of increase in PTH secretion (95 +/- 35% of baseline/min) were similar to those in adenomatous human tissue. These results indicate that 1) acute PTH secretion can be studied in vitro, and that it appears to be similar to the in vivo process; 2) there is a wide variation among adenomatous tissues in the magnitude of secretion stimulated by low calcium concentrations; 3) in addition to varied magnitude of secretion, the rate at which hormone secretion increases in response to a low calcium stimulus varied among adenomas; and 4) PTH secretion from human adenomatous tissue is similar to that from normal primate tissue in both the rate and magnitude of response.

Adenoma↗
PubMed1985

The squash family of serine proteinase inhibitors. Amino acid sequences and association equilibrium constants of inhibitors from squash, summer squash, zucchini, and cucumber seeds.

Six amino acid sequences for trypsin inhibitors isolated from squash, summer squash, zucchini, and cucumber seeds were determined. All these inhibitors along with the two previously sequenced squash inhibitors (1) form the squash inhibitor family. The striking characteristic of the family is that its member inhibitors are very small (29-32 residues, 3 disulfide bridges). The association equilibrium constants with bovine beta trypsin for 6 squash family inhibitors were determined and range from 5.9 X 10(10) to 9.5 X 10(11) M-1.

Amino Acid Sequence↗
PubMed1985

Computerized drug therapy: application of the hand-held microcomputer to dosage regimen design.

For many drugs estimation of a safe and effective dosage regimen is difficult. Typically these drugs exhibit optimal therapeutic activity when drug concentrations in the blood are maintained within narrow limits and considerable intersubject variability exists in their rate of elimination from the body. Computer programs have been written to estimate the size and frequency of dose administration necessary to achieve therapeutic drug concentrations in the blood. The programs utilize pharmacokinetic equations and information on the individual patient's physiologic (e.g., age, weight, sex) and pathologic (e.g., existence of liver or renal disease) status. The drugs studied were gentamicin, theophylline, digoxin, phenytoin and warfarin. The programs were written using the hand-held TRS 80 Pocket Computer with an 8K memory module. These programs have been in use for 3 years and are currently involved in clinical consults approx. 100 times a month.

Computers↗