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Biomedical subjects

D W Thomas

Publications and source records attributed to D W Thomas.

At least 325 records · Page 18Linked to original sources
PubMed1967

Regulation of food intake and obesity.

This is not the place to consider the medical significance of obesity in terms of conditions such as heart disease and hypertension, diabetes, and arthritis. These very complex interrelationships have been dealt with elsewhere (69). We hope that enough evidence has been presented to demonstrate that energy balance is normally maintained by a precise and reliable physiologic mechanism, and that the energy surplus represented by obesity may reflect direct failure of this mechanism or some combination from a variety of neurological, endocrine, enzymatic, and psychological disorders. Environmental conditions as well as genetic and traumatic factors may contribute to the development of obesity. If increasing mechanization brings tus below the level of energy expenditure at which food intake is properly regulated, appropriate habits of exercise will have to be established and maintained.

Adipose Tissue↗
PubMedDate not supplied

Antibiotic prescription for acute dental conditions in the primary care setting.

To determine the pattern of antibiotic prescribing (source and type) for acute dental conditions in the emergency setting, a prospective cross-sectional study was undertaken of 500 consecutive new patients attending the examination and emergency clinic of the Cardiff Dental Hospital in May 1994. The source and type of antibiotics prescribed, the nature of complaint and type of antibiotic prescribed in the primary care and dental hospital setting were recorded. Antibiotic prescription was a feature of the treatment of 30% (149/500) of patients. The 60 patients who had received emergency treatment prior to attending the hospital emergency clinic had been prescribed a total of 14 different types of antibiotics; 41% of these patients had sought treatment from general medical practitioners. Antibiotics were frequently prescribed without generally accepted criteria and there was wide variation in prescribing. Overall, only seven different types of antibiotics were prescribed in the dental hospital setting. The use of second generation antibiotics was more common in general practice than in the dental hospital. The results suggest that many patients with dental pain may seek treatment from medical practitioners, prior to, or in place of, definitive dental treatment. In summary, rationalisation of antibiotic prescription and the provision of emergency dental treatment is needed.

Acute Disease↗
PubMedDate not supplied

Randomized clinical trial of the effect of semi-occlusive dressings on the microflora and clinical outcome of acute facial wounds.

This study investigated whether treatment with occlusive, hydroactive polyurethane dressings affects the microflora and clinical outcome of acute wounds. A randomized, controlled trial was performed on 60 patients with acute facial lacerations. Following primary closure, patients were provided with either a dry-gauze dressing or a hydroactive polyurethane dressing (Cutinova Thin). The wounds were assessed clinically and microbiologically prior to closure, then after 5, 28 and 56 days. The dressing, which was removed at day 5, was also sent for microbiological culture. Wounds treated with the polyurethane dressing showed improved comfort and contour (p < 0.04), less erythema (p < 0.03) and less potential for scarring (p < 0.01) at day 5. At day 28 and day 56, there were no significant differences in the clinical assessment between the test and control groups (p > 0.05). A total of 518 isolates were recovered from the patients during the study. Mean number of isolates and bacterial growth density were calculated in both groups. A similar range of microorganisms were obtained from both treatment groups with no clear difference in organism colonization. This study shows the potential usefulness of facial wounds as a human model for studying acute wound healing responses and anti-scarring therapy. While short-term, clinical benefits of occlusive dressings were evident in the management of acute wounds, these data clearly show that all studies of scarring following acute wounding should extend over at least 3 months post-injury to allow for spontaneous improvement to occur.

Adolescent↗
PubMedDate not supplied

Phenotypic variation in the production of bioactive hepatocyte growth factor/scatter factor by oral mucosal and skin fibroblasts.

Hepatocyte growth factor/scatter factor (HGF/SF) is a pleiotropic growth factor produced principally by cells of mesenchymal origin. HGF/SF is an important mitogen, morphogen, and motogen and plays an important role in wound healing, tumorigenesis and particularly fetal development. Oral mucosal fibroblasts exhibit a fetal phenotype, including an increased extracellular matrix reorganizational ability, cellular migration and experimental wound repopulation in comparison to skin fibroblasts. In this study the expression, production, and bioactivity of HGF/SF by oral mucosal and skin fibroblasts was investigated. Although both oral mucosal and skin fibroblasts expressed HGF/SF, the oral mucosal fibroblasts produced significantly increased amounts of total HGF/SF (p < 0.01) as measured by enzyme-linked immunosorbent assay and bioactive HGF/SF as measured by cell scatter and cell-dissociation techniques (p < 0.01). The possible effect of increased HGF/SF in production mediating the previously described preferential responses of oral mucosal fibroblasts was studied in vitro. Reverse transcriptase-polymerase chain reaction-Western blotting and immunocytochemistry methods all showed that both oral mucosal and skin fibroblasts expressed and produced the c-Met receptor. Recombinant HGF (20-40 ng/mL) however, failed to affect fibroblast repopulation of monolayer wounds or cellular proliferation. In contrast, recombinant HGF significantly increased ECV304 wound repopulation. These studies provide direct evidence of another mechanism by which site-specific variations in fibroblast phenotype may contribute in a paracrine fashion to the rapid reepithelialization and revascularization of oral wounds.

Adolescent↗
PubMedDate not supplied

Use of molecular techniques to study microbial diversity in the skin: chronic wounds reevaluated.

The skin is colonized by an array of microorganisms which form its natural microflora. Disruption to the normal barrier function of the skin (due to trauma or disease) may result in invasion of the dermis by opportunistic bacteria. To date, these organisms, which may contribute to the chronicity of skin wounds, have been analyzed solely by culture methods. It is increasingly realized that standard culture methods of analysis do not accurately reflect the full diversity of complex microflora. This review discusses the limitations of traditional culture approaches and reviews recent advances in molecular microbiological techniques which facilitate a more comprehensive characterization of the microflora within clinical samples. The currently available technologies and techniques are described, as is their use in clinical practice and their potential for diagnostic screening. Chronic venous ulceration of the lower limbs is an important skin disorder in which the microflora invading the dermal tissues contribute to the observed delayed healing. Using chronic leg ulcers as a working example, we show how strict culture and molecular microbiological techniques may be employed, for the first time in combination, to definitively characterize the invading microbial community of the dermis.

Chronic Disease↗
PubMedDate not supplied

Social status does not affect resting metabolic rate in wintering dark-eyed junco (Junco hyemalis).

Studies of wintering birds have demonstrated a correlation between social rank and energy expenditures. It is assumed that dominance is energetically costly because of increased activity, possibly caused by elevated androgen levels. As winter acclimatization leads to an increase in metabolic rate, maintaining dominance status in a cold climate can be a substantial challenge. We measured resting metabolic rates in dominant and subordinate dark-eyed juncos (Junco hyemalis) living in small groups in a controlled winter environment. We found no significant effect of social rank when controlling for body size. It has been shown previously that high testosterone levels during the nonbreeding season can lead to higher body conductance, fat loss, and higher nocturnal body temperature. A hypothesis explaining our result is that for juncos it is preferable to maintain low androgen levels during winter and to maintain social rank using a mechanism other than higher agonistic activity.

Agonistic Behavior↗
PubMedDate not supplied

Torpor and digestion in food-storing hibernators.

Many species of hibernating mammals rely on hoarded food rather than body fat to support winter energy requirements. Here, we evaluate whether the associated ingestive and digestive requirements reduce the benefits that food-storing hibernators can accrue from torpor. Using a simple model, we predict (1) that digestive efficiency could either increase or decrease with increased use of torpor, depending on the Q(10) of digestion relative to the Q(10) of whole-animal metabolism and (2) that increased torpor will result in a linear decrease in energy consumption but an exponential increase in euthermic intake requirements. In 16 captive eastern chipmunks (Tamias striatus), the proportion of time that different individuals spent in torpor was highly variable (29.8%+/-5.9%; 0.0%-86.3%), positively correlated with dry matter digestibility (r2=0.53, P=0.02) and negatively correlated with energy consumption (r2=0.72, P=0.002). Thus, by both increasing conversion efficiency and reducing energy requirements, torpor appears to provide a double benefit for energy conservation by food-storing hibernators. Despite this, a comparative analysis shows that the euthermic intervals of food-storing rodents are four times as long and torpor intervals are half as long as that of fat-storing rodents. Given that required euthermic intake rates are expected to increase exponentially at high levels of torpor, the reduced torpor expression of food-storing species may result from constraints on their ability to load enough food into the gut when euthermic to cover the energy requirements of the subsequent torpor cycle.

Animals↗
PubMedDate not supplied

Nitrogen and energy requirements of the North American porcupine (Erethizon dorsatum).

We measured nitrogen and energy requirements in adult North American porcupines (Erethizon dorsatum) fed three experimental diets differing primarily in crude protein content. Porcupines ingested 497.3-865.4 kJ kg-0.75 d-1, and there was no significant loss of body mass on any dietary treatment. Individuals maintained nitrogen balance on a total nitrogen intake of 389.4 mg N kg-0.75 d-1. The true digestibility of nitrogen was high (88%) but within the range for eutherians. We found metabolic fecal nitrogen to be 0.92 mg N g-1 dry matter intake and endogenous urinary nitrogen to be 223 mg N kg-0.75 d-1. The low value of metabolic fecal nitrogen found for porcupines affects the dry matter intake required for nitrogen balance, and it may allow these animals to exploit nitrogen-poor diets.

Animals↗