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Biomedical subjects

M Holden

Publications and source records attributed to M Holden.

At least 19 recordsLinked to original sources
PubMed1997

The Tsp45I restriction-modification system is plasmid-borne within its thermophilic host.

Thermus species YS45 harbors two small cryptic plasmids of 5.8 (pTsp45s) and approximately 12 kb (pTsp45I). Plasmid pTsp45s has been entirely sequenced, revealing three significant ORFs. In addition to a previously reported thermophilic plasmid-encoded replication protein (Rep), pTsp45s contains two genes for the Tsp45I methyltransferase (M.Tsp45I) and restriction endonuclease (Tsp45I). These two converging genes (tsp45IM and tsp45IR) overlap by 4 bp at their stop codons within an XbaI site. M.Tsp45I (413 aa, 47.0 kDa, recognizing 5'-GTSAC-3') is highly homologous to other m6A-methyltransferases, especially M.EcaI (recognizing 5'-GGTNACC-3'). Tsp45I (332 aa, 37.4 kDa, cleaving 5'-/GTSAC-3') is not homologous to M.Tsp45I, or to other restriction endonucleases. Recombinant Tsp45I is stably produced in E. coli, and cleaves DNA at 65 degrees C with the same specificity as the native enzyme. Therefore, the thermophilic Tsp45I restriction-modification system is plasmid-borne within its native host.

Amino Acid Sequence↗
PubMed1997

Probing the interactions of putidaredoxin with redox partners in camphor P450 5-monooxygenase by mutagenesis of surface residues.

The role of surface amino acid residues in the interaction of putidaredoxin (Pdx) with its redox partners in the cytochrome P450cam (CYP101) system was investigated by site-directed mutagenesis. The mutated Pdx genes were expressed in Escherichia coli, and the proteins were purified and studied in vitro. Activity of the complete reconstituted P450cam system was measured, and kinetic parameters were determined. Partial assays were also conducted to determine the effect of the mutations on interactions with each redox partner. Some mutations altered interactions of Pdx with one redox partner but not the other. Other mutations affected interactions with both redox partners, suggesting some overlap in the binding sites on Pdx for putidaredoxin reductase and CYP101. Cysteine 73 of Pdx was identified as important in the interaction of Pdx with putidaredoxin reductase, whereas aspartate 38 serves a critical role in the subunit binding and electron transfer to CYP101.

Bacterial Proteins↗
PubMed1997

Development and validation of a computerized screening test for personality disorders in DSM-III-R.

The available self-report instruments designed to measure personality disorder (PD) are time-consuming to administer and/or score and can be impractical for routine clinical use. There is a need for a computerized method of personality assessment based on contemporary systems of classification. A computerized DSM-III-R-based questionnaire was developed and validated against the structured clinical interview for DSM-III-R Axis-II disorders on a sample of 60 subjects. The computerized test showed moderate validity as a diagnostic instrument (mean kappa coefficient = 0.47). With adjusted cut-off scores it was valid as a screening instrument (mean sensitivity = 0.87). Antisocial, borderline and avoidant PD scores were strongly correlated across measures and not subject to significant observer bias.

Adult↗
PubMed1995

Measurement of small tissue volumes using Holden's apparatus.

A reproducible method for the estimation of volumes of small tissue samples was needed to allow comparison of the biological activity of tissue explants and to relate symptom improvement to procedures such as adenoidectomy or polypectomy. Holden's apparatus, which utilizes fluid displacement between two chambers, was compared to displacement in a 20 ml syringe. Two observers made four readings each on 20 tissue samples (range 0.37 to 4.70 ml) using both methods for comparison. A two-way analysis of variance for replicated data gave an F ratio of 0.6885 (df = 19; p > 0.8) for Holden's apparatus, and an F ratio of 1.4307 (df = 19; p > 0.1) for the 20 ml syringe. The standard error of the mean for repeated readings on the same sample by an observer was 0.001 ml for Holden's apparatus and 0.014 ml for the syringe method. For accurate estimation of small tissue volumes within 0.01 ml we recommend Holden's apparatus.

Adenoids↗
PubMed1993

Compulsivity and superstitiousness.

The relationship between superstitious beliefs and behaviors, and measures of obsessive-compulsive experiences was examined in this study. Both superstitious beliefs and superstitious behaviors were correlated with measures of compulsivity and obsessionality. Compulsive checking, but not compulsive cleaning (from the MOCI and the CAC-R) were correlated with superstitiousness. Both subscales from the Obsessional Thoughts Questionnaire were correlated with superstitiousness. The implications of these findings for the role of perceived control in obsessive-compulsive phenomena were discussed.

Adult↗
PubMed1993

Measurement of hand microvascular blood flow with isolated cold stress testing and laser Doppler fluxmetry.

Isolated cold stress testing applies cold thermal stress to an extremity for noninvasive study of skin surface temperature as an index of digital microcirculation. In this study, laser Doppler fluxmetry was combined with isolated cold stress testing to examine the relationship between digital thermoregulation (measured by isolated cold stress testing) and digital microcirculatory blood flow (measured by laser Doppler fluxmetry) in 50 healthy men and women. After a 5-minute baseline period, both hands were subjected to cold stress (average, 8 degrees C) for 20 minutes and then returned to room temperature for 20 minutes. Digital temperatures and laser Doppler measurements were graphed to document individual responses. The 25 women had lower digital temperatures, lower laser Doppler fluxmetry values, and less average rewarming than the 25 men. Statistical cluster analysis revealed a cold pattern, found predominantly in women, and a warm pattern, found predominantly in men. These patterns of response may help to elucidate the pathogenesis of the vascular occlusive syndromes occurring predominantly in women.

Adolescent↗
PubMed1989

Glycosylated and carbamylated haemoglobin in uraemia.

Glycosylated and carbamylated haemoglobin were determined in patients with uraemia and/or diabetes mellitus. Glycosylated haemoglobin measured by ion-exchange chromatography (HbA1, HbA1c, HbA1a + b) was elevated in non-diabetic uraemic patients, while colorimetrically determined glycosylated haemoglobin was similar to controls. Patients with diabetes mellitus and normal renal function had similar glycosylated haemoglobin concentrations to those with renal failure. Both methods showed an excellent correlation, independent of renal function, in patients with diabetes mellitus. The HbA1c component was more influenced by diabetes and the HbA1a + b component was relatively more dependent on renal function. Carbamylated haemoglobin was detected in all subjects, but was grossly elevated in uraemia. Carbamylated haemoglobin significantly correlated with renal function and chromatographically determined glycosylated haemoglobin. Data from this study strongly suggests that the apparent elevation of chromatographically determined glycosylated haemoglobin in uraemia is due to the increased formation of carbamylated haemoglobin. However, in patients with diabetes mellitus, independent of renal function, both the chromatographic and colorimetric methods of determining glycosylated haemoglobin are equally valuable and reliable. The non-enzymatic formation of carbamylated haemoglobin in uraemia has several similarities to glycosylated haemoglobin in patients with diabetes mellitus. Carbamylated haemoglobin may have a clinical role as a marker of uraemia and may also have a pathophysiological relevance.

Adult↗
PubMed1988

Carbamylated haemoglobin in chronic renal failure.

Carbamylated haemoglobin was measured by quantifying the release of isopropyl hydantoin by the acid hydrolysis of globin using gas liquid chromatography. Carbamylated haemoglobin was evaluated in 167 subjects including patients with a wide spectrum of renal disease. Grossly elevated concentrations of isopropyl hydantoin (mean values greater than 80 ng IPH/mg globin) were found in chronic renal failure, dialysis and transplant patients with renal failure compared to healthy subjects (15-39 ng IPH/mg globin). The elevated carbamylated haemoglobin correlated with renal function. Carbamylated haemoglobin may act as an indicator of uraemic status and has a potential clinical usefulness and may also have a pathophysiological significance.

Adult↗
PubMed1983

The stressful impact of news of risk for premature heart disease.

Efforts at prevention of disease include case-finding of individuals at high risk and offering to these identified people an intervention to reduce their risk. Although the intention of intervention is to reduce risk, the impact of discovering that one is at high risk may also lead to intrusive ideas and feelings that characterize psychological stress response syndromes. The present study examined these issues with a sample of 1,447 men who were advised of their risk for coronary heart disease in the collaborative Multiple Risk Factor Intervention Trial. Comparisons over three yearly data collections between a usual care and special intervention group showed that the special intervention group reported a far greater level of coping and mastery efforts regarding their risk status. This was accompanied by a much smaller tendency to be bothered by intrusive thoughts, but amount of reported upset did not differ. Finally, a small group of men in both groups indicated continuing high levels of upset across the three years. Clinicians are advised to be watchful for these persons for whom mastery of the news appears to be difficult.

Adaptation, Psychological↗
PubMed1977

Echocardiographic visualisation of the interatrial baffle after Mustard's operation.

Thirty children aged from 7 weeks to 14 years were examined by echocardiography after Mustard's operation for transposition of the great arteries. Discrete and persitent echoes were noted within the original left atrial cavity and contrast echocardiography was used to establish that these originated from the interatrial baffle. In the presence of caval channel obstruction, caused by malposition or shrinkage of the baffle, significant differences were seen in the echocardiographic appearances of the baffle, namely limitation of baffle motion, thickening, and multiplicity of the baffle echoes. These findings suggest that the technique may be of value in the postoperative assessment of patients with transposition of the great arteries.

Adolescent↗
PubMed1973

Tuberculin reactions.

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False Negative Reactions↗