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Biomedical subjects

C McManus

Publications and source records attributed to C McManus.

At least 19 recordsLinked to original sources

Pruritus.

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Pruritus

Self-criticism in adulthood and recalled childhood experience.

We investigated in a sample of 75 medical students the hypothesis that higher levels of self-criticism, a major vulnerability factor for depression, are related to retrospective reports of less satisfactory parenting, even when the potentially confounding factors of mood state and social desirability response set are controlled. At each of 2 measurement times, there were significant cross-sectional correlations between parental ratings and both depression and self-criticism, but the associations with self-criticism were no longer significant when depression was controlled. However, even after controlling for the effects of mood state and social desirability, persons with high levels of self-criticism at both measurement points (high trait self-criticism subjects) reported significantly worse relationships with their mothers than did the remaining subjects. They were also more likely to report below average relationships with both parents jointly.

Adult

Genetic selection in farmed deer.

Selection is the major tool used by breeders to improve the genetic quality of their livestock. Traditional methods of selection are well proven and useful in improving the economic merit of livestock. The performance of an animal is affected by its genetic quality and by the environment in which it is reared. While environmental improvement is expensive and requires continuous inputs, genetic improvement is cumulative and permanent, provided that selection is maintained. To select an animal on its genetic merit account must be taken of the environmental effects on its performance. Comparisons between the performance of animals on different farms or in different years are not valid unless they have genetic material in common. The speed at which genetic improvement is passed on to the rest of a population is affected by the variation and heritability of the traits being selected, the selection intensity and the generation interval. The deer population in the United Kingdom has a high degree of variation for important traits but the selection intensity is low and the generation intervals are larger than in other farmed species. Central performance testing, group breeding schemes and the use of artificial insemination are tools which will be important in the genetic improvement of farmed deer.

Agriculture

Fourth report of the cooperative, open-ended study of slowly growing mycobacteria by the International Working Group on Mycobacterial Taxonomy.

The open-ended study of the International Working Group on Mycobacterial Taxonomy is an ongoing project to characterize slowly growing strains of mycobacteria that do not belong to well-established or thoroughly characterized species. In this fourth report we describe two numerical taxonomic clusters that represent subspecies or biovars of Mycobacterium simiae, one cluster that encompasses the erstwhile type strain of the presently invalid species "Mycobacterium paraffinicum," one cluster that is phenotypically very similar to Mycobacterium avium and Mycobacterium intracellulare but may be a separate genospecies, one cluster that appears to be phenotypically distinct from M. avium but reacts with a nucleic acid probe specific for M. avium, and three tentatively defined clusters in proximity to a cluster that encompasses the type strain of Mycobacterium malmoense. Of special practical interest is the fact that one of the latter three clusters is composed of clinically significant scotochromogenic bacteria that can be misidentified as the nonpathogenic organism Mycobacterium gordonae if insufficient biochemical tests are performed.

Agglutination Tests

Sensitivity to the displacement of facial features in negative and inverted images.

Subjects have previously been reported to show difficulties in recognising faces which are either inverted or in photographic negative. Experiments are reported in which a two-alternative forced-choice technique was used to measure sensitivity for distinguishing faces which have been modified by having the eyes moved vertically or horizontally. Subjects were less sensitive to such changes for inverted faces or negative faces, and were even less sensitive for faces that were both inverted and negative. No such effects were found for a control stimulus consisting simply of three solid circles in the same positions as the eyes and mouth of a face. When the stimuli consisted of eyes, nose, and mouth, but without a surround, no evidence of inversion or negation effects was found, which suggests that a facial surround is necessary. When the stimulus consisted of a facial surround with the eyes, nose, and mouth replaced by solid circles, effects of negation were found, but no effects of inversion. This dissociation of the effects of negation and inversion may suggest that they are the result of different underlying mechanisms.

Adult

The influence of measurement precision on medical findings.

Medical researchers, epidemiologists and clinicians are all concerned with the observed incidence rates of various diseases and diagnostic findings. Such findings are necessarily based on imprecise procedures and instrumentation. The present study describes the theoretical extent to which the precision of instruments and procedures contributes to reported distribution curves and incidence rates of diagnostic findings. A numerical method is described for separating underlying distribution curves from the observed distribution curves which are distorted by measurement error. The method is illustrated by two examples: blood pressure measurements and QRS axis distributions in the ECG.

Blood Pressure Determination

Bioenergetic studies in adult patients recovering from semi-starvation.

A model of energy-nitrogen balance developed in animals was adapted to the study of human bioenergetics. By creating balance conditions and steady-state formula infusion rates, each of the needed components of energy and nitrogen balance can now be measured with a high level of accuracy. A comprehensive description of energetic efficiency at the whole body level is possible using appropriate mathematical modeling. Key questions in human bioenergetics await these results, and our laboratory is currently undertaking these studies.

Adult

Nutrient bioavailability from nasojejunally administered enteral formulas: comparison to solid food.

The net absorption and retention of energy, fat, nitrogen, and six elements (potassium, phosphorus, calcium, magnesium, sodium, and chloride) from two intrajejunally infused enteral formulas were compared to solid food. Undernourished patients (group 1) underwent two consecutive 7-day balance studies on a predigested protein-low fat (elemental) formula and an intact protein-standard fat (polymeric) formula, the initial diet selected randomly. Periods were isocaloric and isonitrogenous, but differed in the amounts of remaining elements. The undernourished patients in group 2 ate a solid food standard hospital diet for the 7-day balance study in an amount equal in energy and protein to group 1. There were no major differences in the nutrient absorption between the three diets. Nitrogen balance was similar for the two formulas (mean +/- SD) (elemental 6.1 +/- 3.5 g/day; polymeric 4.8 +/- 3.2 g/day) and solid food (5.2 +/- 3.5 g/day), and the balance for the six remaining elements was approximately proportional to the amount supplied. Subjective tolerance of both formulas was good, with a tendency for superior tolerance of the polymeric formula. We conclude that for the nutrients investigated, 1) intrajejunally administered enteral formulas are capable of renourishing hospitalized patients with an efficacy similar to that of solid food, and 2) predigestion of the formula does not improve absorption.

Biological Availability

A neurological basis for visual discomfort.

Certain patterns of stripes are judged to be unpleasant to look at. They induce illusions of colour, shape and motion that are sometimes perceived predominantly to one side of fixation. People who suffer frequent headaches tend to report more illusions, and if the pain consistently occurs on the same side of the head the illusions tend to be lateralized. The parameters of the patterns that induce illusions (including their shape, spatial frequency, duty cycle, contrast and cortical representation) closely resemble those that elicit epileptiform electroencephalographic abnormalities in patients with photosensitive epilepsy. The viewing conditions under which such abnormalities are likely to appear are also those under which more illusions are seen.

Adolescent

Measurement of muscle mass in humans: validity of the 24-hour urinary creatinine method.

Measuring muscle mass is an important component of the nutritional assessment examination and a suggested index of this body space is the 24-h urinary excretion of creatinine. The method originated from studies in a variety of animal species in whom early workers found a parallelism between total body creatine and urinary excretion of creatinine. Assuming that nearly all creatine was within muscle tissue, that muscle creatine content remained constant and that creatinine was excreted at a uniform rate, an obvious "corollary" was that urinary creatinine was proportional to muscle mass. The so-called "creatinine equivalence" (kg muscle mass/g urinary creatinine) ranged experimentally from 17 to 22. One of the limiting factors in firmly establishing this constant and its associated variability was (and is) the lack of another totally acceptable noninvasive technique of measuring muscle mass to which the creatinine method could (or would) be compared. An improved understanding of creatine metabolism and a variety of clinical studies in recent years has tended to support the general validity of this approach. However, specific conditions have also been established in which the method becomes either inaccurate or invalid. While creatinine excretion may serve as a useful approximation of muscle mass in carefully selected subjects, there remains a need for accurate and practical indices of muscle mass for use in the individuals in whom the method cannot be reliably applied.

Adult

Biochemical composition of muscle in normal and semistarved human subjects: relevance to anthropometric measurements.

Anthropometric methods aimed at assessing muscle size in undernourished subjects assume a constant proportionality between the mass (i.e., size) and composition (specifically protein-energy content) of this tissue. This assumption was examined in three autopsy groups: controls (n = 11, sudden traumatic death), early semistarvation (n = 6), acute preterminal disease), and chronic semistarvation (n = 34, severe weight loss over time). Results of semistarved groups were expressed relative to respective control value. Early semistarvation produced no detectable change in muscle mass, protein, or total energy content (per gram wet weight), although RNA and glycogen were -50 to -70% of control value (p less than 0.05). Chronic semistarvation caused muscle atrophy (-54.2%), but not all measured constituents were reduced to the same degree. The results were H2O--52.9%, collagen--46%, noncollagen proteins--65.3%, total lipids--40%, DNA--54.1%, RNA--81.7%, glycogen--90.3%, and total energy--59.6%. Muscle per unit mass in chronic semistarvation thus reflects relatively more H2O and less protein and energy when compared to normal tissue. About 85 to 95% of muscle protein-energy loss can be detected by anthropometric measurements of muscle size; the remaining 5 to 15% depletion of protein and energy is masked by muscle compositional changes. Proper interpretation of anthropometric data requires an understanding of these unmeasured but important compositional differences in normal and semistarved muscle.

Anthropometry

Anthropometric measurement of muscle mass: revised equations for calculating bone-free arm muscle area.

Arm muscle area (AMA, cm2) is currently calculated from triceps skinfold thickness (TSF, cm), and midarm circumference (MAC, cm). In assessing the accuracy of the current equation by comparison to AMA measured by computerized axial tomography, error in each of the four approximations made was found to result in a 20 to 25% overestimate of AMA. Two correctible error sources were: a 10 to 15% overestimation caused by assuming a circular midarm muscle compartment and a 5 to 10% overestimation due to inclusion of midarm cross-sectional bone area. Corrected AMA equations for men and women were respectively: [(MAC - pi x TSF)2/4 pi] - 10, and [MAC - pi x TSF)2/4 pip] - 6.5. With two additional study groups, the overall improved accuracy of the new equations was confirmed, although the average error for a given patient was 7 to 8%; the relationship between corrected AMA and total body muscle mass was established [muscle mass (kg) = (ht, cm2) (0.0264 + 0.0029 x corrected AMA)]; and the minimal range of corrected AMA values compatible with survival (9 to 11 cm2) was defined. Bedside estimates of undernutrition severity and prognosis can therefore be calculated from two simple measurements, TSF and MAC.

Adult

Handedness, anxiety and sex differences.

Anxiety scores of 35 male and 35 female students (28 right-handers, 23 left-handers and 19 mixed-handers) were assessed in relation to the handedness classification of each individual. Females were found to show higher anxiety scores than were males; but in contradiction to previous findings, left-handers and mixed-handers were not found to be more anxious than right-handers. Extremes of handedness, however, were closely related to anxiety scores, with the strongly right-handed and the strongly left-handed both showing higher anxiety scores than those whose hand preferences were less extreme.

Anxiety