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Biomedical subjects

M J White

Publications and source records attributed to M J White.

At least 73 records · Page 4Linked to original sources
PubMed1991

Inositol metabolism in yeasts.

Because of its accessibility to genetic and molecular studies, Sacch. cerevisiae is an attractive organism in which to pursue studies of the complex roles of phosphoinositides and other inositol-containing metabolites. Biochemical studies have clearly demonstrated that PI, PIP, PIP2 and the inositol phosphates derived from them exist in Sacch. cerevisiae. It is clear that they are synthesized and turned over following pathways similar to those described in higher eukaryotes. Recent studies on yeast have also suggested that inositol phospholipids may play roles in complex signalling pathways similar to those detected in animal cells. In addition, inositol has been demonstrated to function in yeast as a global regulator of phospholipid synthesis. This regulation occurs on a transcriptional level and is highly complex. It is not yet known whether similar inositol-mediated regulation of phospholipid synthesis occurs in other eukaryotes.

Inositol↗
PubMed1991

Medical malpractice: an empirical examination of the litigation process.

New data on medical malpractice claims against a single hospital in which a direct measure of the quality of medical care is available are used to investigate the roles of the negligence rule and incomplete information in the dispute settlement process in medical malpractice. We find that the quality of medical care (negligence) is an extremely important determinant of defendants' medical malpractice liability. More generally, we find that the data are consistent with a model in which plaintiffs are poorly informed ex ante about whether there has been negligence, file suit to gather information, and either drop the case if they find that negligence was unlikely or settle for a positive payoff if they find that negligence was likely. We also find that the cases are resolved earlier in the litigation process when the parties are more certain, one way or the other, about the likelihood of negligence.

Data Collection↗
PubMed1991

Procurement and transplantation of colonized cadaver skin.

Cadaver skin is an important adjunct to burn care. This study was designed to measure the percentage of its contamination prior to grafting and to determine the clinical safety of its use. Cadaveric homografts from 19 donors were harvested, frozen, thawed, and used as a biological dressing. Cultures were obtained at the time of harvest, after incubation in antibiotics, and at actual transplantation. The homografts were 43 per cent, 68 per cent, and 50 per cent contaminant-free, respectively. Two of 14 patients lost their homografts due to infection. However, no patient developed an infection or lost the homograft due to an organism identified during the pretransplantation processing. Therefore, contaminant-free and slightly contaminated cadaver skin can be used safely as homografts.

Adolescent↗
PubMed1990

Oxygen free radicals and wound healing.

Oxygen-dependent mechanisms for intracellular killing by leukocytes result in the generation of highly reactive oxygen metabolites. These are called oxygen radicals. The purpose of this article is to define the oxygen free radical and the methods by which it is generated as well as the mechanisms by which these radicals produce injury. Specifically, recent studies investigating the role of oxygen-derived free radicals in wound healing are reviewed.

Free Radicals↗
PubMed1990

Stress, coping, and quality of life in adult kidney transplant recipients.

The purpose of this study was to identify specific stressors and coping strategies identified by adult kidney transplant recipients in the first 6 months after transplantation. Quality of life was used as the outcome measure. Subscales were rationally constructed based on literature review and logic for both the stress and coping scales. Health-related items were identified as most stressful including uncertainty about whether the transplant will be a success and concern about risk of infections and/or viruses. Work-related items were least stressful. Strongly endorsed coping strategies included items on the Distancing/detachment and Self-control/accepting responsibility subscales. Quality of life scores were significantly higher after the transplant than before. Total stress was the important predictor of quality of life before transplant. Both total stress and total coping were important predictors of quality of life after transplant. The expanded transplant nursing role provides an opportunity to identify stressors and suggest appropriate coping strategies early in the transplant experience.

Adaptation, Psychological↗
PubMed1990

Stress, coping, and quality of life in family members of kidney transplant recipients.

This study explored specific stressors and identified coping strategies used by family members of kidney transplant recipients in the first 6 months following transplantation. Quality of life was also briefly examined as the outcome measure. Health-related items were identified as most stressful, and work-related items as least stressful. Self-controlling and problem-solving coping strategies were most frequently used, and escape/avoidance strategies were least used. Findings from this study have implications for development of specific teaching plans for transplant recipient families, as well as for collaborative team exploration of family stress and coping.

Adaptation, Psychological↗
PubMed1990

Effects of agricultural development policies on migration in peninsular Malaysia.

State planning plays a central role in Malaysia's social and economic development. The government's rural development policies are designed to promote agricultural incomes and help counterbalance ethnic inequalities. The Federal Land Development Authority (FELDA) implements one of the internationally most successful land development and resettlement programs. In this article, we quantify the impact of FELDA settlements on local out-migration rates, linking macro and micro approaches and using data from the Malaysian Family Life Survey, national censuses, and other sources. A model of instantaneous migration rates specifies an individual's migration rate as a function of individual-level sociodemographic characteristics, the level of urbanization of the origin and destination, and the extent of rural development at the district of current residence. Our results show that in the late 1960s and early 1970s, the existence of rural development centers in a district reduced the levels of out-migration to pre-1965 levels.

Agriculture↗
PubMed1989

Characterization of a single copy gene encoding ferredoxin I from pea.

We have isolated, mapped, and sequenced a genomic clone containing the ferredoxin I (Fed-1) gene from Pisum sativum. The gene is present as a single copy per haploid genome. It has no introns, and it specifies a 753-nucleotide transcript encoding a 149-amino acid protein including a 52-residue transit peptide. Upstream sequences from Fed-1 contain several elements with similarity to transcriptional regulatory elements from RbcS and Cab genes, and gel mobility shift assays show that nuclear extracts from light-grown pea leaves contain one or more DNA binding activities specific for Fed-1 5'-flanking sequences. RbcS and Cab regulatory sequences are only weak competitors for this binding, however, and the RbcS and Cab similarities mostly lie outside of the region essential for binding. These data are discussed in terms of previously observed physiological differences between the light responses of Fed-1 and other genes.

Amino Acid Sequence↗
PubMed1989

The human pressor response during and following voluntary and evoked isometric contraction with occluded local blood supply.

1. Changes in heart rate and blood pressure were observed, in nine healthy subjects, during and after voluntary and electrically evoked isometric contractions of the triceps surae under conditions of local circulatory arrest. 2. The progressive increases in heart rate and blood pressure seen during 2 min voluntary and evoked contractions at 30% of maximal voluntary contraction were not significantly different in the two conditions. On cessation of contraction but with circulatory arrest maintained, heart rate fell to control levels while blood pressure fell to a similar though still significantly elevated level in both conditions. Elevated blood pressure was maintained for 2 min until the circulatory occlusion was removed; however it was maintained at a significantly higher level for the last 60-90 s of occlusion following electrically evoked contractions compared to voluntary contraction. 3. Comparison of the responses to voluntary and involuntary electrically evoked contractions suggest that 'central command' is not necessary for the initial increases in heart rate and blood pressure to occur. In addition the removal of central command on cessation of contraction need not account for the return of heart rate to control levels or the drop in blood pressure at that time. Maintained blood pressure elevation during circulatory occlusion would seem to be due to the trapping of chemical substances within the muscle interstitium.

Adult↗
PubMed1989

Management of maxillofacial and neck soft-tissue injuries.

Maxillofacial injuries sustained during sporting events may involve any variety of soft-tissue or bony injuries. As in any traumatized patient, more extensive injuries must be excluded and the basic principles of maintaining an airway and restoration of circulation maintained. The face and neck take on a particular significance when one considers the complexity of function and significant aesthetic value of the structures of the face and neck. Careful inspection, palpation, and examination of function assure the accurate diagnosis of injuries. Specific injuries to the specialized areas of the face and neck are discussed with particular attention to the potential underlying injuries to the facial nerves, parotid duct, and lacrimal systems. The importance of recognizing septal nasal hematomas and external ear hematomas are discussed.

Athletic Injuries↗
PubMed1989

Long-chain alcohol production by yeasts.

Fourteen yeast strains from six genera were analysed for the presence of long-chain alcohols, the highest levels being found in Candida albicans. The major alcohols synthesized were saturated, primary alcohols with C14, C16 or C18 chain length with relative proportions of C16 greater than C18 greater than C14. In C. albicans synthesis of long-chain alcohols occurred only after the end of exponential growth. Long-chain alcohol contents were lower in organisms grown aerobically as compared with anaerobically and contents of all three classes increased as the concentration of glucose was raised from 1.0 to 30.0% (w/v). In anaerobic cultures greatest alcohol contents were obtained using medium containing 10% (w/v) glucose. Substituting glucose (10%, w/v) with the same concentration of galactose in aerobic cultures greatly decreased contents of long-chain alcohols, while inclusion of 10% (w/v) glycerol virtually abolished their synthesis. Supplementing anaerobic cultures with odd-chain fatty acids induced synthesis of odd-chain alcohols, Nitrogen limitation induced long-chain alcohol synthesis in aerobically grown Candida maltosa and quantities were increased with conditions of glucose excess and nitrogen limitation.

Aerobiosis↗
PubMed1988

Electrically evoked isometric and isokinetic properties of the triceps surae in young male subjects.

The relationship between electrically evoked isometric and isokinetic properties of the triceps surae have been studied in 11 healthy male subjects. The results showed that the time to peak tension (TPT) and half relaxation time (1/2 RT) of the maximal twitch were 110 +/- 11 ms and 82 +/- 11 ms respectively, and the peak rates of rise of contraction (delta P50, delta P200) and relaxation (delta PR50, delta PR200) at 50 and 200 Hz were 0.36 +/- 0.07, 0.48 +/- 0.08 and 1.27 +/- 0.33, 1.25 +/- 0.27% Po ms-1 respectively. The decline in force during a fatigue test was significantly (P less than 0.02) associated with the decrease in maximal relaxation rate (r = 0.79). The TPT was significantly (P less than 0.05) and inversely related to delta P50 and delta P200. The mean angle specific torque-velocity relationship for the 11 subjects was adequately described by the empirical exponential equation of the form: V = 16.5 (e-P/30.8-e-84.3/30.8) where V = velocity (rads s-1) and P = torque (Nm). The only significant association found between the isometric and isokinetic properties of the muscle was between delta PR200 and the torque expressed at a given velocity of 4 rads s-1. This lack of association between the two variables is difficult to explain with certainty but it is suggested that it may be due to the differential effects of Ca2+ release and uptake and cross-bridge turnover rate in the two situations.

Adult↗
PubMed1988

Human malignant ascites and histamine-induced protein leakage from the normal microcirculation.

The accumulation of malignant ascites is a significant cause of morbidity and mortality in patients with intraabdominal malignancies. However, the cause of malignant ascites is unknown. In this study, we used the rat cremaster muscle preparation to determine if and how malignant ascites could produce protein leakage from normal blood vessels which would lead to fluid accumulation in the peritoneal cavity. The rat cremaster muscle, with nerves and blood vessels to the animal intact, was prepared for microscopic observations of the microcirculation. Serum albumin was tagged to fluorescein isothiocyanate and injected into the rat. Fluorescent microscopy was used to quantitate leakage of the tagged albumin into the interstitial tissue. Malignant ascites was collected from a patient with metastatic breast cancer. The ascites fluid was placed on the cremaster muscle and it induced protein leakage from the normal blood vessels of this tissue. Protein leakage was partially blocked by diphenhydramine (10(-4) M) and by mast cell depletion with compound 48/80. There was a high level of C3a in the malignant ascites solution but C3a did not increase during the exposure period. These data suggest that activated complement in malignant ascites may release histamine from mast cells to cause protein leakage of the normal vasculature. The movement of protein into the peritoneal cavity would be followed by water, thus increasing the volume of the ascites and exacerbating the clinical condition.

Animals↗
PubMed1988

Effect of glucose and long-chain fatty acids on synthesis of long-chain alcohols by Candida albicans.

Candida albicans, grown aerobically in glucose-containing media, produced C14, C16 and C18 saturated long-chain alcohols only after the end of exponential growth. Contents of C14 alcohols were always lowest, and C16 and C18 alcohol contents about equal. Contents of all three classes of alcohol increased as the concentration of glucose in aerobic cultures harvested after 168 h incubation was raised from 1.0 to 30.0% (w/v). However, in 168 h anaerobic cultures, greatest long-chain alcohol contents in organisms were obtained using media containing 10% (w/v) glucose. Substituting glucose (10%, w/v) with the same concentration of galactose in aerobic cultures greatly decreased contents of long-chain alcohols, while inclusion of 10% (w/v) glycerol virtually abolished their synthesis. Supplementing anaerobic cultures with odd-chain fatty acids induced synthesis of odd-chain alcohols. Maximum conversion of fatty acid to the corresponding long-chain alcohol was observed with heptadecanoic acid. The effect of glucose on production of heptadecanol from exogenously provided heptadecanoic acid was similar to that observed on synthesis of the three major even-chain alcohols in media lacking a fatty-acid supplement. Cell-free extracts of organisms catalysed in vitro conversion of palmitoyl-CoA to 1-hexadecanol.

Alcohols↗