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Biomedical subjects

J Cheney

Publications and source records attributed to J Cheney.

9 recordsLinked to original sources
PubMed1991

Prevalence of circulating heartworm antigen in dogs in northeastern Colorado.

Heartworm antigenemia was evaluated and found to be negative in 1010 dogs in Northeastern Colorado that were examined at the Colorado State University Veterinary Teaching Hospital. The estimated prevalence of canine heartworm for the native Northeastern Colorado population was determined to be 0.3% and is similar to the prevalence reported 10 years ago in the same area. We conclude there has not been an increase in prevalence of heartworm in the last 10 years; because of the low prevalence, there is no need for routine testing or testing and prophylaxis in the study area at this time.

Animals↗
PubMed1990

Thermodynamics of the interaction of inhibitors with the binding site of recombinant human renin.

The independent subsite model is widely used for the design of peptide inhibitors of enzymes with extended active sites. This model assumes that the subsites are independent of each other and that the free energies of binding contributed by the several subsites are additive. We questioned the strict application of this model for structure-activity studies, since one can, a priori, conceive of likely deviations from this model. Accordingly, we tested the independent subsite model by measuring the thermodynamic binding parameters of a series of peptide inhibitors of human renin. This enzyme-inhibitor system was chosen as a model by virtue of the high degree of specificity of renin for its natural substrate, angiotensinogen, and the availability of a large number of structurally similar peptide inhibitors. Although we found the general mode of binding of these renin inhibitors to be primarily hydrophobic, serious deviations from additivity and independent subsite model constraints were observed. We conclude that an important determinant of binding is most probably the conformation assumed by the peptide inhibitor in solution. Thus, we suggest that caution be exercised in using affinity constants to assess the interactions of peptide inhibitors with human renin and possibly with other enzymes having extended binding sites. Furthermore, the thermodynamic parameters of a class of compounds provide more information as to the mode of binding of ligands to their respective receptors than do dissociation constants.

Amino Acid Sequence↗
PubMed1989

Carbon monoxide assessment of smoking in chronic obstructive pulmonary disease.

Chronic Obstructive Pulmonary Disease (COPD) is a major, often fatal, drain on health-care resources. Most cases of COPD result from Tobacco Dependence, and smoking cessation slows COPD's progression. But there is very little information on treating Tobacco Dependence in COPD patients. In preparation for clinical trials using monetary payments to motivate reduced smoking, as assessed by breath carbon monoxide (CO) levels in COPD patients, we have addressed three issues. First, surveying 182 advanced COPD patients, we found that CO levels above 8 parts per million (ppm) were strongly associated with a self-report of current smoking, and that CO levels correlated neither with COPD severity, nor with age: about one-third of these patients were currently smoking. Second, among 12 still-smoking COPD patients serially observed for 8 h. CO half-life averaged about 6.5 h. Third, 8 patients reinforced with lottery tickets for CO reductions significantly reduced CO levels during 2 test weeks, mainly by deferring smoking before scheduled CO measurements.

Air Pollution↗
PubMed1988

Calculation of NH...pi hydrogen bond energies in basic pancreatic trypsin inhibitor.

Ab initio molecular orbital procedures have been employed to investigate associations of the Tyr35 aromatic ring with Gly37 NH and Asn44 NHz in the X-ray crystal structure of basic pancreatic trypsin inhibitor. Formamide and phenol were used to model the key features in the protein. The calculations provide evidence for energetically favorable NH...pi hydrogen bonding.

Aprotinin↗
PubMed1973

Protein synthesis during the differentiation of sporangia in the water mold Achlya.

During the synchronous differentiation of sporangia in the absence of added nutrients, the water mold Achlya bisexualis (Coker and Couch) actively synthesized protein. Inhibition of protein synthesis at any time during the sporulation process completely inhibited further differentiation. Large changes in the rate of radioactive amino acid uptake resulted in changes in the specific activity of the cellular amino acid pool. The rate of protein synthesis was calculated from the amino acid pool specific activity and the incorporation of isotope into protein. During the 1st h after induction of the sporulation process, the rate of protein synthesis increased to two times the initial value. The amino acid precursors for this synthesis were supplied by the degradation of preexisting protein. Proteolytic enzyme activity assayed in vitro increased in proportion to the in vivo rates of protein synthesis and degradation. Differentiation was accompanied by a slight decline in dry weight of the mycelium as well as by a decrease in the protein content, whereas the relative size of the amino acid pools remained constant.

Amino Acids↗