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Biomedical subjects

J Allen

Publications and source records attributed to J Allen.

At least 37 records · Page 2Linked to original sources
PubMed1995

Pediatric organ donation: impact of medical examiner refusal.

OBJECTIVES: To examine the national Pediatric Intensive Care Unit (PICU) experience regarding Medical Examiner (ME) refusal of organ procurement from potential donors. To review our experience regarding PICU mortalities, organ donation, and impact of the ME on the organ donation process. DESIGN: National survey of PICU directors requesting demographics, type of ME system, perceptions of ME responsiveness to organ donation, and data regarding potential donors and their outcomes. Also, a retrospective chart review of all PICU deaths from 1990 to 1992 at a tertiary care center, noting the number of potential organ donors, ME cases, those harvested, rejected, and reason for rejection. PARTICIPANTS: PICU directors selected from a list of Pediatric Section members of the Society of Critical Care Medicine. The response rate was 59%. The chart review was performed in a 1000-bed hospital with a 12-bed PICU. RESULTS: PICU directors' perceptions of ME responsiveness to organ donation were not determined by size of PICU, area served, type of hospital, ME system, or means of contacting the ME. ME refusal accounted for 15% and 16% of total refusals in the survey and chart review, respectively. Family refusal accounted for 49% and 28% in these same groups. Survey respondents' hints and suggestions to decrease denial and increase organ donation focused on improved communication (61% and 33%), and education (16% and 55%). CONCLUSIONS: ME refusal does impact on pediatric organ donation, but not as significantly as family refusal. Increased organ procurement in ME-related cases will require improved communication between MEs, physicians, and the Organ Procurement Organizations (OPOs).

Attitude of Health Personnel↗
PubMed1995

Caring in nursing: rhetoric or reality?

Nursing requires both a scientific and humanistic basis for practice. Nursing is a human science; a market-place ideology and a technological environment limit caring.

Empathy↗
PubMed1994

Careers in academic general practice: problems, constraints, and opportunities.

Changing priorities in the NHS have underlined the crucial importance of academic general practice in providing quality training and research to underpin developments in general practice. Unfortunately, several problems and constraints mean that the full potential of general practitioners to make a contribution to teaching and research has not been realised. These issues are examined and recommendations for improvements are made. Obstacles to career development for academics in general practice should be removed. The funding of academic general practice should be the same as for other medical disciplines. Vocational training for general practice should be extended to include research and audit methods, particularly for doctors interested in an academic career. Above all, the long term objective should be to integrate undergraduate and post-graduate general practice to increase the overall effectiveness of teaching and research and hence the quality of service general practice.

Academic Medical Centers↗
PubMed1994

Bone mineral density of total body, spine, and femoral neck in children and young adults: a cross-sectional and longitudinal study.

Bone mineral density (BMD) of total body (TBMD), lumbar spine (L2-4), and femoral neck was measured in 266 normal subjects (136 males) aged 4-27 years (mean 13 years) using dual-energy x-ray absorptiometry (DXA). BMD of all sites increased significantly with age until 17.5 years in males and 15.8 years in females, except for femoral neck BMD in females, which peaked at age 14.1 years. Males had higher peak TBMD, which was attributed to greater weight and lean tissue mass. In contrast, despite a later timing, peak L2-4 BMD in males was not different from that in females. Before peak BMD, weight was the best predictor of TBMD and L2-4 BMD in both sexes (r2 ranged from 0.77 to 0.88), whereas femoral neck BMD was predicted equally by height and weight. Longitudinal information collected from 53 (25 boys) of these children, aged 4-16.9 years, showed that the average annualized gain in TBMD was 0.047 g/cm2 for boys and 0.039 g/cm2 for girls. No significant difference in the association between age and BMD (slopes) was found between cross-sectional and longitudinal data for either sex. We conclude that the timing for peak BMD was consistent for total body, lumbar spine, and femoral neck for each sex. The earlier peak BMD in females is most likely related to earlier puberty. The cross-sectional normative data of this study are useful in serving as a standard for serial assessment in health and disease states.

Absorptiometry, Photon↗
PubMed1994

Dietary calcium intake in 18-year-old women: comparison with recommended daily intake and dietary energy intake.

Average dietary calcium intake and energy intake of 113 18-year-old university students in Western Australia was examined. Four-day, weighted diet records, including 1 weekend day, were completed by the subjects. A large proportion of the students (68%) had an average daily calcium consumption below the 800 mg recommended by the National Health and Medical Research Council of Australia. A strong positive association was also found between dietary calcium and dietary energy intakes. Many young women on self-imposed energy reduction diets are at risk of a dietary calcium intake deficit at a time when it should be enhanced. These findings are significant for nursing practice as they indicate the need for further health education concerning the importance of dietary calcium in young women.

Adolescent↗
PubMed1994

Simplified body-surface electrocardiographic maps with depolarization magnitude and direction.

A new technique is presented for extracting the magnitude and direction of ventricular depolarization at the body surface from surface electrocardiographic (ECG) map data. Bipolar electrocardiograms were obtained from 36 sites on the chest surface in five normal subjects. The direction and magnitude of depolarization as seen from the chest surface were calculated for 18 body-surface areas centred between electrode positions V1 and V6. Each area was bounded by three electrodes with an electrode spacing of 5 cm. A major depolarization component could be calculated for all triangular areas, with 48% of areas having a smaller second component. The area with the greatest magnitude in each subject had a depolarization vector pointing downwards and to the left, with an average angle to the horizontal of 55 degrees. This was consistent with an average angle of 51 degrees obtained from the subjects' 12-lead electrocardiograms. There was more variability in vector angle between adjacent areas on the right-hand side. At the V5/V6 areas, close to the cardiac apex, the vector component had an upwards orientation in all subjects, opposing the overall downward component of ventricular depolarization. The technique was able to determine local depolarization directions which were in agreement with the normal cardiac vector derived from standard electrocardiography. Reversal of the vector direction close to the cardiac apex and the collision of depolarization components from different directions could be detected. This simple form of body-surface mapping can reduce the essential features of depolarization to a single map, and provide information not directly available from a 12-lead electrocardiogram.

Adult↗
PubMed1994

Effects of maternal hospitalization in early childhood: anticipated anxiety associated with an analog separation for childbirth and surgery.

Assessed early childhood anticipation of anxiety in response to analog 3-day maternal hospitalization for surgery or childbirth. Reaction to analog nonhospital separation was also assessed. Within each condition, gender effects were examined. Participants were 120 first-grade children at four elementary schools. Between-groups comparisons showed maternal separation for surgery was anticipated as more anxiety provoking, whereas anxiety associated with separation for childbirth and nonhospital separation was anticipated as similar. In general, within each separation situation, girls and boys anticipated similar levels of anxiety.

Anxiety, Separation↗
PubMed1994

Effects of age and gender on dichotic sentence identification.

There is converging evidence that aging causes a progressive decline in the central processing of speech and that this decline is greater for left-ear than for right-ear input. In the present paper we investigated, by means of a dichotic sentence identification paradigm, some parameters of the "left-ear effect." We analyzed the clinical records of 356 individuals, 203 males and 153 females, to whom the Dichotic Sentence Identification (DSI) Test had been administered as part of routine audiometric assessment. Subjects ranged in age from 9 to 91 yr. The DSI test was always carried out in two modes: free report (FR) and directed report (DR). In the FR mode the subject reported what was heard in both ears. In the DR mode the subject reported only what was heard in one precued ear. In half of the trials the right ear was precued, in the other half the left ear was precued. Findings confirm a progressively larger right-ear advantage, or left-ear deficit, with increasing age. We document this effect in both the FR and DR modes, then demonstrate that the effects cannot be attributed to interaural asymmetries in threshold sensitivity. Comparison of male and female data suggest a gender difference in the effect of age on the left-ear deficit. Males show a larger effect then females in both modes of test administration. Finally, we propose a model of dichotic listening performance that attempts to explain ear asymmetry as the linear combination of an auditory/structural component and a task-related/cognitive component. We then show how these hypothetical components change with age in the present sample.

Adolescent↗
PubMed1994

Linear IgA disease: a heterogeneous disease.

Data from our series of 70 patients support the hypothesis that linear IgA disease is a heterogeneous disease as regards clinical features, target antigens and immunogenetics. The clinical presentation varies as regards age of onset and severity of skin and mucosal involvement and scarring. The use of split skin and of the novel substrate cylindroma has identified 2 target antigens. The majority of patients have a target antigen associated with epidermal cells and possibly cylindroma hemidesmosomes. A minority have a dermal antigen which resembles collagen VII on cylindroma. There is an association with HLA-B8, -DR3, Cw7 and with the linked rare tumour necrosis factor alpha allele, but this is not universal. These differences do not correlate with each other.

Adolescent↗
PubMed1994

Linear IgA disease: cylindroma demonstrates heterogeneity of the target antigens.

Serum from 58 patients with linear IgA disease was tested by indirect immunofluorescence on the novel substrate cylindroma, which produces an abundance of basement membrane components. The use of split skin and of cylindroma has identified 2 target antigens. The majority of patients have a target antigen associated with epidermal cells and similar in distribution on cylindroma to hemidesmosome proteins. A minority have a dermal antigen with the distribution of collagen VII on cylindroma. These data support the hypothesis that linear IgA disease is a heterogeneous disease with regard to the target antigens.

Adenoma↗
PubMed1994

Molecular overlap of the IgA target antigens in the subepidermal blistering diseases.

Linear IgA disease (LAD) has circulating IgA auto-antibodies which have been found to be associated with epidermal- and dermal-derived antigens. The localization and molecular weight(s) of the IgA target antigen(s) implicated in LAD and their relationship to the target antigens for the IgA antibodies in bullous pemphigoid (BP) and cicatricial pemphigoid (CP) are unknown. Sera from patients with all 3 diseases who had circulating IgA antibodies were studied by immunoblotting with both epidermal and dermal extracts. Our findings indicate that there is heterogeneity in the localization and molecular weights of the target antigen(s), with multiple bands demonstrated with some sera. Three principal target antigens were identified with molecular weights of 110-120, 160-180 and one approximately 285 kD. These antigens were common to all 3 diseases and were found in 25 patients. These results suggest that the target antigens for IgA basement membrane zone antibodies in LAD, BP and CP are multiple, complex in composition and may differ from the conventional BP antigens.

Autoantibodies↗
PubMed1993

The M gamma chain of human fetal hemoglobin is an A gamma chain with an in vitro modification of gamma 141 leucine to hydroxyleucine.

We have reanalyzed the structure of the gamma T-15 peptide from the minor M gamma chain of human hemoglobin (Hb) F. Amino acid analysis confirmed that the Leu 141 residue was missing from position 9 of this peptide, and liquid secondary ion mass spectrometry indicated that it was replaced, not by methionine (residue mass 131) as previously believed, but by an amino acid of mass 129. By analogy with the recently reported oxidation of the corresponding leucine at position gamma 141 of the unstable Hb Atlanta, it appears that the M gamma chain also results from the oxidation of gamma 141 to hydroxyleucine (residue mass 129). The finding that the proportion of the M gamma chain increased when red cell lysates were prepared with carbon tetrachloride prompted us to reinvestigate the oxidation mechanism involved in the formation of beta 141 hydroxyleucine in Hb Atlanta. Oxidation of the beta 141 residue could be detected when carbon tetrachloride was used in the lysis protocol, while conversion of oxyhemoglobin to carbon monoxyhemoglobin prior to carbon tetrachloride treatment prevented oxidation. It therefore appears that the hydroxylation of Leu 141 is not an in vivo process in the circulating red cell. Perhaps leucine at position 141 of the beta, gamma, and delta chains (and at position 136 of the alpha chain), which forms a contact with heme and is located directly across the heme plate from the E helix, is oxidized to hydroxyleucine at a very low rate forming minute amounts of modified chains; this process is accelerated by treatment with agents such as carbon tetrachloride and prolonged exposure to air.

Adult↗
PubMed1993

Bullous systemic lupus erythematosus--a variable disease.

We describe a patient with the rare diagnosis of 'Bullous Systemic Lupus Erythematosus'. She is unusual in presenting with classical dermatitis herpetiformis, before the emergence of systemic features. In addition, on indirect immunofluorescence on sodium chloride split skin, there was epidermal binding. Immunoblotting was negative for type VII collagen.

Adult↗
PubMed1992

Incomplete process of recombinant human platelet-derived growth factor produced in yeast and its effect on the biological activity.

Partially purified recombinant human Platelet-derived Growth Factor BB homodimer isolated from yeast culture media contains variable amounts of unprocessed PDGF-BB. This unprocessed PDGF-BB is found as a result of incomplete cleavage of the precursor to form the mature protein. Although the signal peptide is efficiently removed, a fraction of the PDGF secreted has an extended sequence corresponding to the truncated yeast alpha-factor leader. The data suggest that it is the amino acid chain from the truncated a-factor leader and not the sugar moiety attached to it that is responsible for the higher mitogenic activity found in this unprocessed molecule compared to highly purified PDGF-BB.

Amino Acid Sequence↗