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Biomedical subjects

K Gardiner

Publications and source records attributed to K Gardiner.

115 records · Page 7Linked to original sources

Transverse alternating field electrophoresis and applications to mammalian genome mapping.

The transverse alternating field electrophoresis system is a pulsed field gel apparatus that has been used to separate DNA molecules that range in size from a few thousand to approximately 7 million base pairs. This apparatus uses a vertical gel and a simple electrode arrangement to produce electric fields that are uniform across all lanes of the gel. The velocity of identical molecules does not vary from lane to lane, and hence there is no distortion in the paths of the DNA. The performance of this system is illustrated here using the chromosomes from S. pombe and S. cerevisiae, and restriction enzyme digested mammalian DNA. The mobility of molecules up to 1100 kilobase pairs is linear with size and can be accomplished in overnight runs. Resolution of very large molecules requires electrophoresis for several days, but molecules from 200 to 7000 kilobase pairs can be separated on a single gel. This electrophoresis system has been used extensively in the construction of a physical map of human chromosome 21, and examples of this application are discussed.

Animals↗

Effects on respiratory morbidity of occupational exposure to carbon black: a review.

Carbon black is a substance of world importance, both in terms of tonnage production and its special ability to strengthen rubber. Its carbonaceous nature and respirable size give rise to concern regarding its effect on respiratory morbidity for those involved in its manufacture and use. A number of studies have used chest radiographs, spirometry and respiratory symptoms as means of assessing the various populations, but almost all of the studies have either methodological shortcomings or fail to report the necessary detail. However, exposure-related effects are evident in those populations studied in terms of small opacities, reduction in forced expiratory volume in 1 s and forced mid-expiratory flow, and symptoms of chronic bronchitis.

Animals↗

Noise and the classical musician.

OBJECTIVES: To test the hypothesis that noise exposure may cause hearing loss in classical musicians. DESIGN: Comparison of hearing levels between two risk groups identified during the study by measuring sound levels. SETTING: Symphony orchestra and occupational health department in the west Midlands. MAIN OUTCOME MEASURES: Hearing level as measured by clinical pure tone audiometry. RESULTS: Trumpet and piccolo players received a noise dose of 160% and 124%, respectively, over mean levels during part of the study. Comparison of the hearing levels of 18 woodwind and brass musicians with 18 string musicians matched for age and sex did not show a significant difference in hearing, the mean difference in the hearing levels at the high (2, 4, and 8 KHz) audiometric frequencies being 1.02 dB (95% confidence interval -2.39 to 4.43). CONCLUSIONS: This study showed that there is a potential for occupational hearing loss in classical orchestral musicians.

Audiometry, Pure-Tone↗

Intestinal amino acid absorption during sepsis.

Sepsis has been shown to cause a decrease in mesenteric blood flow in association with ultrastructural changes in the small intestine and impaired immune, barrier, and metabolic functions of the gut. These impairments in the structure and function of the gastrointestinal tract may have a detrimental effect on the morbidity and mortality of sepsis. Two recent studies have shown that the ability of the small intestine to absorb amino acids is also impaired during sepsis, but the systemic and cellular mechanisms of this impairment are not known. Release of cytokines induced by systemic bacteria or endotoxin may lead to a reduction in the synthesis of transporter proteins by the enterocyte at a time when there is reduced availability of both luminal (because of anorexia) and circulating (because of reduced mesenteric blood flow) substrates. Future research needs to investigate the systemic and local mediation of the sepsis-induced reduction in intestinal amino acid absorption and the possibility of correcting the defect by the administration of enteral nutrients, hormones, or drugs.

Amino Acids↗

The role of the imino transporter protein in sepsis-impaired intestinal proline absorption.

Recently, sepsis has been shown to impair intestinal amino acid absorption in addition to gut metabolic and barrier functions. We investigated intestinal proline absorption in a rabbit model of sepsis. Twelve hours after intraperitoneal injection of lipopolysaccharide, proline uptake by everted jejunal sacs prepared from septic animals (480.4 +/- 67.4 nmol per sac per hour) was significantly reduced compared with controls (846.8 +/- 73.5 nmol per sac per hour) (p < .001 by t test). We next investigated whether reduced expression of transporter proteins contributed to the impaired intestinal proline uptake during sepsis. The proline (imino) carrier of rabbit jejunum is covalently bound by fluorescein isothiocyanate (FITC) and/or phenylisothiocyanate with irreversible inhibition of proline uptake. This binding and inhibition is prevented by sodium chloride and L-proline. Single-cell suspensions of rabbit enterocytes were prepared 12 hours after intraperitoneal injection of lipopolysaccharide/saline or saline alone. Enterocytes were incubated for 30 minutes in tris(hydroxymethyl)aminomethane/ethylenediaminetetraacetate (Tris/EDTA) buffer; buffer with 1 mM phenylisothiocyanate; or buffer with 10 mM proline, 100 mM sodium chloride, and 1 mM phenylisothiocyanate. After incubation with 10 microM FITC in Tris/EDTA buffer for 15 minutes, the percent positivity and fluorescent intensity of FITC binding to enterocytes were determined by using flow cytometry. Sepsis significantly reduced the percentage of enterocytes binding FITC and the fluorescent intensity of FITC binding of proline/sodium chloride-pretreated or untreated cells. This suggests that sepsis depresses the expression of imino transporters by rabbit enterocytes, which may explain the reduced intestinal proline absorption.

Amino Acid Transport Systems, Neutral↗

[New forms of gene transcripts in human and mouse intersectin].

New human and mouse cDNAs which are homologous to human intersectin gene (ITSN) mapped on a q22.1-22.2 region of human chromosome 21 have been obtained. ITSN gene structure has been determined using nucleotide sequences of human chromosome 21 presented in nucleotide's data bases. The analysis of human and mouse ITSN gene transcripts revealed that their pre-mRNA splicing could occur in different ways. New form of ITSN gene transcripts with alternatively spliced SH3C domain (exon 25 and 26) was detected in different human and mouse tissues. The other splice form with absence of exons 6-14 that results in reading frame shift and stop-codon formation was identified in the mouse adult lung and kidney. In addition, we showed alternative splicing of exons 20, 25 and part of exon 6.

Adaptor Proteins, Vesicular Transport↗