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Biomedical subjects

J K Clark

Publications and source records attributed to J K Clark.

At least 19 recordsLinked to original sources
PubMed2002

Modified gamma-cyclodextrins and their rocuronium complexes.

A series of per-6-substituted cyclodextrin derivatives was synthesized as synthetic host molecules for rocuronium, a steroidal muscle relaxant. By forming host-guest complexes with rocuronium, these cyclodextrin derivatives reverse the muscle relaxation induced by rocuronium in vitro and in vivo. The isothermal microcalorimetry data are consistent with the biological data supporting the encapsulation mechanism of action. Binary and biphasic complexes are reported with NMR experiments clearly showing free and bound rocuronium. [structure: see text]

Androstanols↗
PubMed2001

Evaluation of a rapid western immunoblotting procedure for the diagnosis of bovine spongiform encephalopathy (BSE) in the UK.

Bovine brain tissue samples from 625 UK cattle, clinically suspected as bovine spongiform encephalopathy (BSE) cases, were used in a blind analysis to assess a rapid Western immunoblotting technique (Prionics Check; Prionics AG, Zurich), which detects bovine disease-specific protease-resistant prion protein (PrP(Sc)). By means of statutory histopathological examination, 599 of the 625 cattle were confirmed as BSE cases by the demonstration of spongiform encephalopathy, the remaining 26 being classified as negative. Duplicate samples from the same animals were also examined by electron microscopy for the presence of abnormal brain fibrils (scrapie-associated fibrils; SAFs). The Prionics technique showed a high sensitivity, particularly when compared with the fibril detection test; the detection rates were 99.3% and 92.0% respectively, with histopathology being used as the "gold standard". The false negative results by the Prionics test were possibly related to the sampling procedure. Analysis of 50 BSE-positive samples revealed similar glycoprofiles, the majority of PrP(Sc)isoforms being di-glycosylated protein. The Prionics test also detected PrP(Sc)in the four brain samples from the 26 histopathologically negative animals, apparently reducing the specificity of the test to 84.6%; however, confirmatory positive results in these samples were obtained by demonstrating SAF or by immunohistochemical examination, or both. It was concluded that the Prionics test detected PrP(Sc)in a small percentage (0.64%) of clinically suspected BSE cases showing no spongiform change. Since January 2000, the Prionics Western blot test has been introduced as one of the statutory tests for the diagnosis of clinically suspected BSE and scrapie cases in the UK.

Animals↗
PubMed2000

Non-depolarizing neuromuscular blocking activity of bisquaternary amino di- and tripeptide derivatives.

Herein we describe the synthesis of novel di- and tripeptide derivatives with two quaternary nitrogen groups attached and the biological testing of these compounds for neuromuscular blocking (NMB) activity in vitro and in vivo. The short peptide scaffold was selected because it offers potential for desired distance between the two pharmacophoric quaternary nitrogen groups, short duration of action, straightforward synthesis, and compatibility with an injectable formulation. From a small series of compounds 20c,e are identified as effective non-depolarizing NMB agents in vitro and in vivo in anesthetized cats and Rhesus monkeys with potencies similar to those of the clinical reference compounds rocuronium (4) and suxamethonium (2) (monkey ED(90) = 0.68, 0.23, 0.16, 5.04 micromol/kg, respectively). These new peptide derivatives 20c,e have similar potency and onset time but longer duration and slower recovery than the clinically used reference compounds. The structure-activity relationships described for this chemical series lead to the conclusion that the di- or tripeptide fragment can be regarded as an alternative template to the steroid or aliphatic ester of previously reported NMBs and within this tripeptide-derived series clog P correlates well with in vitro NMB activity.

Amines↗
PubMed2000

Conformationally constrained anesthetic steroids that modulate GABA(A) receptors.

Various cyclic ether and other 3 alpha-hydroxyandrostane derivatives bearing a conformationally constrained hydrogen-bonding moiety were prepared. Their anesthetic potency and their binding affinity for GABA(A) receptors, measured by intravenous administration to mice and inhibition of [(35)S]TBPS binding to rat whole brain membranes, were compared with that of known anesthetic 3 alpha-hydroxypregnan-20-ones. Synthetic steroids with similar in vitro and in vivo activities to the endogenous 3 alpha-hydroxypregnan-20-ones all had an ether oxygen on the beta-face of the steroid D-ring. These results suggest that for optimal GABA(A) receptor modulation, the hydrogen bond-accepting substituent should be near perpendicular to the plane of the D-ring on the beta-face of the steroid.

Androstanols↗
PubMed2000

Adolescent girls' knowledge of and attitudes toward breast self-examination: evaluating an outreach education program.

BACKGROUND: The purpose of the study was to analyze the effectiveness of a one-hour educational intervention to increase knowledge about and improve attitudes towards breast self-examination (BSE) and early cancer detection among adolescent girls. METHODS: The sample used in this quasi-experimental study was selected from schools participating in an education program provided by a regional health education center. The instrument and scales used in the study were developed and pilot-tested for reliability and validity in the area schools prior to the start of the study. The sample consisted of 137 adolescent girls who provided consent forms and participated in the intervention. The comparison group, which consisted of students attending the same schools, was scheduled to receive the intervention at a later date. RESULTS AND CONCLUSIONS: Findings suggest that a one-hour lesson can improve knowledge and attitudes of adolescent girls with respect to BSE and early cancer detection. Suggestions for further research are discussed.

Adolescent↗
PubMed1999

Identification and characterization of a protein destruction signal in the encephalomyocarditis virus 3C protease.

The amino acid sequence LLVRGRTLVV, which is probably located in a strand-turn-strand structure, has been identified as a protein destruction signal in the rapidly degraded encephalomyocarditis virus 3C protease. Mutations within this sequence reduced the susceptibility of the 3C protease toward ubiquitination and degradation in rabbit reticulocyte lysate. This signal is transferable, since poliovirus 3C protease, which is a poor ubiquitin-mediated proteolytic system substrate, was found to be ubiquitinated and degraded when the signal sequence was either generated at an internal location in the protein or fused to the N terminus. An evaluation of the behavior of 3C protease proteins containing mutations in the signal region indicates that considerable variability in the primary structure is tolerated, although the conservation of certain features appears to be required for signal function. Two E3 ubiquitin-protein ligases that recognize the encephalomyocarditis virus 3C protease as a substrate were also partially purified. One of these was identified as the previously described E3alpha, and this was shown to require the destruction signal sequence to catalyze efficiently the ubiquitination of the 3C protease. The other is a Ubc5-dependent E3 that appears to recognize a different, unidentified feature of the 3C protease.

3C Viral Proteases↗
PubMed1998

Comparison of scrapie-associated fibril detection and Western immunoblotting for the diagnosis of natural ovine scrapie.

Detergent- and proteinase K-treated extracts of grey matter were prepared from four regions of the brains of 106 sheep with scrapie, diagnosed clinically and by the demonstration of spongiform encephalopathy. The extracts were examined by electron microscopy for the presence of scrapie-associated fibrils and by Western immunoblotting for the disease-specific abnormal prion protein (PrPSc). As a diagnostic method, Western immunoblotting proved to be more sensitive than electron microscopy, the detection rates in the 106 sheep being 97 and 91% respectively (medulla), 99 and 76% (cerebellum), 95 and 88% (frontal cerebral cortex) and 93 and 61% (occipital cerebral cortex). Neither fibrils nor PrPSc could be detected in comparable brain extracts from 25 control sheep which had shown no clinical or histopathological evidence of scrapie.

Animals↗
PubMed1998

Pharmacists' concerns and suggestions related to the sale of tobacco and alcohol in pharmacies.

A random sample of Pharmacists in Indiana was selected and surveyed regarding their thoughts and comments on the sale of tobacco and alcoholic products by pharmacies. A total of 212 pharmacists provided written responses to an open-ended question. The replies were then synthesized into major themes. The majority of comments categorized revealed strong opposition to pharmacies selling tobacco and alcohol products. The most frequently occurring message regarding the sale of these products by pharmacies was that it goes against the pharmacist's role as a professional health care provider and may harm their image. For some pharmacists, this issue posed a moral dilemma between caring for patient safety and the economic incentives provided by the sale of tobacco and alcohol. Based on these findings, a follow-up phone survey was conducted to solicit suggestions from pharmacists on how to advocate against the sale of tobacco and alcohol by pharmacies. The majority of pharmacists strongly recommended that they need to do more among themselves and within their store environment, rather than have regulations imposed on pharmacies when it comes to limiting the sale of these products.

Adult↗
PubMed1998

Angiotensin II induces p67phox mRNA expression and NADPH oxidase superoxide generation in rabbit aortic adventitial fibroblasts.

Superoxide radical (O2-) is ubiquitously critical to the bioactivity of endothelial nitric oxide. In angiotensin-dependent hypertension, vascular O2- levels rise and impede endothelium/nitric oxide-dependent vascular relaxation. We have reported that the major O2- source in the rabbit aorta is adventitial fibroblast phagocyte-like NADPH oxidase and shown that angiotensin (Ang) II treatment of adventitial fibroblasts causes a concentration-dependent increase in particulate NADPH-dependent O2-. From cultured rabbit aortic adventitial fibroblasts treated or not treated with Ang II, we prepared particulate fractions and measured lucigenin-enhanced chemiluminescence. Because [Sar1,Thr8]-Ang II, a generalized antagonist of Ang II and plausible inhibitor of the conversion of Ang II, reversed Ang II (10 nmol/L)-induced NADH- and NADPH-dependent O2- to basal levels, we tested the effect of the inhibitor of aminopeptidase N, amastatin (10 micromol/L), and found no effect on Ang II-stimulated O2-. Ang(1-7), Ang III, and Ang IV also were not effective in stimulating O2- levels at concentrations similar to those of Ang II. Kinetic analysis showed a rise in NADPH oxidase O2- production in response to Ang II, which peaks at 3 hours and returns to basal levels by 16 hours. p67phox, a cytosolic factor, appears to be affected at both the level of transcription and protein synthesis because actinomycin and cycloheximide individually inhibited the observed effect. A partial sequence of p67phox was recovered by reverse transcriptase from mRNA harvested from cultured rabbit aortic adventitial fibroblasts. Furthermore, the p67phox mRNA transcript in aortic fibroblasts is induced by Ang II before the peak of NADPH oxidase by Northern analysis and ribonuclease protection assays. These data suggest that Ang II stimulates NAD(P)H oxidase O2- generation in fibroblasts of aortic adventitia via transcriptional activation of p67phox. These data also provide preliminary evidence for the regulation of factors of the NADPH oxidase and potentially provide a novel means by which to abrogate the development of O2(-)-dependent hypertension.

Amino Acid Sequence↗
PubMed1997

Localization of a constitutively active, phagocyte-like NADPH oxidase in rabbit aortic adventitia: enhancement by angiotensin II.

Superoxide anion (O2-) plays a key role in the endogenous suppression of endothelium-derived nitric oxide (NO) bioactivity and has been implicated in the development of hypertension. In previous studies, we found that O2- is produced predominantly in the adventitia of isolated rabbit aorta and acts as a barrier to NO. In the present studies, we characterize the enzyme responsible for O2- production in the adventitia and show that this enzyme is a constitutively active NADPH oxidase with similar composition as the phagocyte NADPH oxidase. Constitutive O2--generating activity was localized to aortic adventitial fibroblasts and was enhanced by the potent vasoconstrictor angiotensin II. Immunohistochemistry of aortic sections demonstrated the presence of p22(phox), gp91(phox), p47(phox), and p67(phox) localized exclusively in rabbit aortic adventitia, coincident with the site of staining for O2- production. Furthermore, immunodepletion of p67(phox) from adventitial fibroblast particulates resulted in the loss of NADPH oxidase activity, which could be restored by the addition of recombinant p67(phox). Further study into the regulation of this adventitial source of O2- is important in elucidating the mechanisms regulating the bioactivity of NO and may contribute to our understanding of the pathogenesis of hypertension.

Angiotensin II↗
PubMed1995

Health education curricula in residential schools for the deaf.

The purpose of the present study was to determine the extent to which comprehensive (K-12) school health education was required. Permission to modify survey questions from the American School Health Association and the National School Board Association was obtained. As part of a larger study, ten items of the questionnaire were used to identify the status of health education in residential schools for the deaf. The questionnaire was mailed to institutions listed in a Reference Issue of the American Annals of the Deaf. Twenty-five institutions responded and results were tabulated using descriptive statistics. Twenty-two (88%) of the responding schools indicated a comprehensive health instruction program was in place, with 60% of respondents had specified time requirement for health instruction. The majority of responding institutions reported that teachers responsible for teaching the health curriculum to the deaf were not required to be certified in health education. Health education certification for educators of the deaf would assist in upgrading the quality of health education in residential schools for the deaf.

Curriculum↗
PubMed1988

Effects of quinolones on mitogen-stimulated human mononuclear leucocytes.

The effects of several quinolone compounds on mitogen-stimulation of normal human mononuclear leucocytes were studied. In these experiments, mononuclear leucocytes were obtained from heparinized whole blood of healthy young adult donors by Ficoll-hypaque sedimentation. The cells were cultured in the presence of both mitogen and various concentrations of the quinolone compounds. Control cultures (without the addition of the quinolones) were examined concurrently. Our data suggests that the quinolones tested, with the exception of rosoxacin (acrosoxacin) at a concentration of 2.5 mg/l, neither impair nor stimulate activation of lymphocytes by the mitogen phytohaemagglutinin (PHA) when used at the concentrations obtained during therapy.

4-Quinolones↗
PubMed1983

Effects of moxalactam and cefuroxime on mitogen-stimulated human mononuclear leukocytes.

The effect of moxalactam and cefuroxime on mitogen-stimulated human peripheral blood mononuclear leukocytes was studied. Mononuclear leukocytes, mitogen, and antibiotic were added to microtiter wells. Cells were cultured for 3 days, pulsed with tritiated thymidine, and then counted. Compared with control cell cultures, treated cultures showed phytohemagglutinin responsiveness to be depressed by the addition of moxalactam at concentrations of 25 to 200 micrograms/ml (P less than 0.001) and by cefuroxime at concentrations of 50 to 200 micrograms/ml (P less than 0.02 to P less than 0.01). The depressive effect on blastogenesis was less marked when concanavalin A was used. Unstimulated lymphocyte transformation responses were also depressed by both antibiotics at all concentrations (P less than 0.05). Preincubation of mononuclear leukocytes with antibiotic for 2 h, followed by washing and culturing in an antibiotic-free medium, did not depress transformation response. When antibiotic was added 24 h after mitogen, depression of response was insignificant. The data from this study suggest that two new beta-lactam antibiotics, at concentrations achievable in serum when used therapeutically, may have immunosuppressant effects. It remains to be established whether these effects are clinically important.

Adult↗