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Biomedical subjects

C Alexander

Publications and source records attributed to C Alexander.

At least 127 records · Page 7Linked to original sources
PubMed1990

[99mTc-2-methoxy-isobutyl-isonitrile in the diagnosis of coronary heart disease: results of a multicenter study].

A total of 226 patients was studied in a phase-III multicenter trial to compare the results of stress/rest 99mTc-MIBI with 201TI scintigraphy and/or coronary arteriography. The evaluation of planar and SPECT imaging was based on a semiquantitative visual scoring. A congruent diagnosis was generated from all planar 201TI and 99mTc-MIBI scintigrams performed in 36 patients. In 62 of 63 patients, SPECT-studies with 99mTc-MIBI and 201TI led to an identical diagnosis. In one patient a positive result was obtained with 201TI-SPECT whereas 99mTc-MIBI was negative. Segmental agreement for 1509 SPECT segments was 85.7%, for 554 planar segments it was 86.6%. In comparison to coronary arteriography, performed in 180 patients, the overall sensitivity for the correct diagnosis of coronary artery disease (CAD) was 86% for planar MIBI scintigraphy or 92% for MIBI-SPECT. Overall specificity was 100% for planar imaging and 57% for SPECT. The low specificity of MIBI-SPECT was probably due to high prevalence of CAD in this study population. In a subgroup of 43 patients, who underwent coronary angiography, identical results were found with 99mTc-MIBI and 201TI. Only one patient showed a positive scintigraphic result with both 99mTc-MIBI and 201TI without angiographically proven stenosis greater than 50% or prior myocardial infarction. Vessel sensitivities in stenosed coronary arteries (greater than 50% stenosis) were 54% for the LAD and 87% for the RCX/RCA areas with MIBI-SPECT, or 51% or 79% for planar scintigraphy, respectively. Vessel specificities for SPECT were 65% in the LAD or 52% in the RCX/RCA, or 90% or 83% in planar imaging.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Functional assessment of elderly patients after percutaneous aortic balloon valvuloplasty: New York Heart Association classification versus functional status questionnaire.

Monitoring functional status in patients with cardiac disease has traditionally been done by using the New York Heart Association (NYHA) classification system. For various reasons, we found the NYHA system difficult to apply to elderly patients. We proposed that the functional status questionnaire (FSQ), which measures the ability to perform tasks, would more accurately assess the functional status of the elderly. In a study in 37 patients with a mean age of 76 years, who had aortic stenosis, we measured FSQ and NYHA scores at baseline, 1 month and 3 months. The difference in questionnaires was evident by the 3-month measurement. Individual patients were better evaluated by the FSQ. Six patients had an FSQ score of less than 72 (suggesting severe functional impairment) at 3 months but only two patients gave symptoms scored as NYHA class III or IV (cardiac disability). Five of six patients had a recurrent cardiac event subsequent to the 3-month follow-up. Changes in functional performance preceded symptomatic deterioration that was reflected only by the FSQ scores. The FSQ system more reliably predicted outcome than the NYHA system and appears to be a more useful tool in the evaluation of elderly patients with cardiac disease.

Activities of Daily Living↗
PubMed1989

Asbestos-associated disease: a review.

Asbestos and its potential for adversely affecting health remain a source of concern to several sectors of society. Since it rarely occurs in the absence of occupational exposure to asbestos, and because it is potentially preventable, asbestosis was recently defined as a reportable occupational disease in Texas. An overview of the cardinal characteristics of the asbestos minerals and their associated health effects is presented. The role of the primary physician in diagnosis and counseling of individuals with asbestos-associated diseases is addressed.

Asbestosis↗
PubMed1987

Expression of K2 isotype mRNA in normal and Basilea rabbits.

Molecular genetic techniques were used to study the regulated expression of the kappa light chains in the rabbit. Two isotypic kappa genes, kappa 1 and kappa 2, have been identified in the genome of all rabbits; however, the majority of secreted immunoglobulins produced by most domestic rabbits bear only K1 light chains. S1 nuclease protection experiments utilizing a single-stranded cDNA probe encoding the K2 constant region were performed to identify K2 mRNA in normal rabbits and in the mutant Basilea rabbit strain in which K2 light chains were first described. Varying amounts of K2 message were observed in the non-Basilea samples, between 0.05-1% of the K2 RNA found in a comparable preparation of Basilea RNA. Evidence for alternatively spliced messages was also noted. In addition, a K2 oligonucleotide probe is described which will distinguish between the K2 allotypic forms, bas1 and bas2.

Animals↗
PubMed1986

Allotype-specific probes. A molecular approach to the study of serologically defined determinants.

A new approach to the study of serologically defined immunoglobulin determinants is described. We designed DNA probes which distinguished between the rabbit kappa light chain allotypic sequences in Northern analyses of mRNAs and Southern analyses of genomic DNAs. S1 nuclease protection experiments are described which detect allotype-specific sequences in as little as 100 pg of total RNA. The use of molecular biological techniques overcomes many of the problems inherent in using serological reagents and techniques. In addition, the sensitivity of the assays described here allows the detection of low level expression of the allotypic genes. This work was extended to include the discrimination of the VHa allotypes.

Animals↗
PubMed1985

The Unpleasant Events Schedule: a scale for the measurement of aversive events.

This paper reports reliability and validity data on the Unpleasant Events Schedule (UES), a 320-item scale that assesses stressful life events. The UES assesses both the frequency and aversiveness of events within a 1-month time frame. Rational, empirical, and factorial scales were derived from the UES. Of these, nine scales were retained that were mutually independent, demonstrated good internal reliability, and tapped various dimensions of clinical interest. A short 53-item form of the UES also was developed. The UES correlated moderately (r = .37) with depression. A discriminant analysis revealed that the UES contributed significantly above and beyond scores on the PES (MacPhillamy & Lewinsohn, 1982) to the proportion of variance in discriminating depressed from nondepressed subjects.

Adolescent↗
PubMed1985

Hormonal control in a state of decreased activation: potentiation of arginine vasopressin secretion.

Behaviorally induced stress is associated with increased arginine vasopressin (AVP) secretion. In this report we describe a phasic conditioned response of AVP secretion yielding 2.6-7.1 times normal plasma concentration of this hormone in association with a physiological state of decreased activation, that associated with the mental technique of "transcendental meditation" (TM) in long-term practitioners (6-8 years of regular elicitation). Such a very large phasic response of AVP was previously unknown in the normal physiology of AVP. This elevation was not accompanied by elevation of plasma osmolality. Unstylized ordinary eyes closed rest in a separate group of subjects studied in the same manner was associated with normal plasma AVP concentration. Galvanic skin resistance (GSR) increased during both TM and rest with significantly larger increase associated with TM. Other measures of activation, including muscle metabolism, and the Spielberger Anxiety Inventory indicated marked relaxation in association with TM. In previous research it has been shown that blood pressure does not change acutely during this behavior. These observations indicate that neither stress nor operation of other usual homeostatic control mechanisms are responsible for elevated for AVP in the meditators. It is speculated that the apparently unique mechanism of TM-induced AVP secretion may be more specifically related to the behavioral effects of meditation.

Adult↗
PubMed1984

ESR of a nitroxide radical and its radical pair in irradiated 1-hydroxyxanthine single crystals.

Single crystals of 1- hydroxyxanthine have been X-irradiated at 77 K and studied by ESR at 300 K. A nitroxide radical formed by abstraction of a hydrogen atom at N1 is the primary species formed by the radiation. A nitrogen hyperfine tensor with principal values of 0.8, 2.6, and 13.6 G and a g tensor with principal values of 1.9985, 2.0031, and 2.0099 have been determined. These results indicate a spin density of 0.24 on N1. Pairwise trapping of the nitroxide radical was also detected and principal values of the dipolar coupling tensor were found to be 140.7, -69.4, and -67.8 G. These data indicate effective radical separations of 7.3 A and are consistent with molecular layer spacings of 3.5 A in this crystal structure.

Cyclic N-Oxides↗
PubMed1983

Use of Trypanosoma equiperdum infected rabbits as a source of splenic mRNA; construction of cDNA clones and identification of a rabbit mu heavy chain clone.

Rabbits were infected by Trypanosoma equiperdum and the splenic mRNA was isolated. In vitro translation of this RNA and immunoprecipitation with anti-light chain, anti-heavy chain, anti-mu and anti-VH antibodies demonstrated that T. equiperdum infection elicits large quantities of splenic mRNA encoding mu and kappa chains. The mu and gamma heavy chains and the kappa light chains synthesized in the cell-free translation system were specifically immunoprecipitated by antisera to heavy chain VHa and light chain kappa b allotypes. In vitro labeling of spleen cells from trypanosome-infected animals demonstrated that the biosynthetically labeled IgM has a mu chain of higher molecular weight than the mu chain synthesized by in vitro translation, a difference that is largely abolished when cellular glycosylation is blocked with the antibiotic tunicamycin. Enrichment for heavy chain or light chain mRNA was achieved by fractionating mRNA from trypanosome-infected animals on a sucrose gradient. cDNA clones carrying mu heavy chain sequences were produced using a 'one tube' protocol and identified by cross species hybridization and hybridization selection. Infection of rabbits with T. equiperdum followed by sucrose gradient enrichment of splenic mRNA has provided sufficient quantities of mRNA encoding mu heavy chain suitable for cDNA cloning.

Animals↗