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Biomedical subjects

J Mercer

Publications and source records attributed to J Mercer.

At least 37 records · Page 2Linked to original sources
PubMed1993

Physiological correlates of painful stimulation in preterm infants.

OBJECTIVE: The study investigates the physiological responses of preterm infants to procedures that are routinely performed in intensive care nurseries. Changes in heart rate, respiration rate, and oxygen saturation were examined as indicators of the level of discomfort experienced by the infant during the procedures. DESIGN: Clinical descriptive. Systematic observations of the infants were conducted during periods of rest as well as during routine interventions. SETTING: All observations were recorded from monitored preterm infants in the intensive care units of two urban hospitals. PATIENTS: Thirty-five preterm infants 24-30 weeks gestational age and weighing < 2,000 g at birth. Data were collected from all infants in the units who met the weight criterion. INTERVENTIONS: The researchers observed the infants while the intensive care nursery staff were performing routine care procedures. Observations were made during procedures that adults would consider to be painful, such as injection, heel stick, tape removal, and squeezing of the heel to induce blood flow after heel stick, as well as nonpainful procedures, such as handling, temperature taking, alcohol swabbing, patting, taping a tube, feeding, and placing a pacifier. MAIN OUTCOME MEASURES: Heart rate, respiration rate, and oxygen saturation were recorded from infant monitors. Mean values of the three measures during procedures were compared with mean values before and after procedures. RESULTS: Significant differences (p < 0.001) were found among pre-, peri-, and post-procedures for all three outcome measures. Heart rate and respiration rate means were significantly (p < 0.001) higher during procedures that adults consider to be painful than in those regarded as nonpainful. Oxygen saturation was lower (p < 0.001) for painful procedures than for nonpainful procedures. Gender and infant size comparisons yielded inconclusive results. CONCLUSION: The outcome measures appear to be reliable indices of preterm infant responses to painful stimulation.

Body Weight↗
PubMed1992

Neutralization of multiple laboratory and clinical isolates of human immunodeficiency virus type 1 (HIV-1) by antisera raised against gp120 from the MN isolate of HIV-1.

Vaccines prepared from the envelope glycoprotein, gp120, of the common laboratory isolate of human immunodeficiency virus type 1 (HIV-1) (IIIB/LAV-1) elicit antibodies that neutralize the homologous virus but show little if any cross-neutralizing activity. This may be because the principal neutralizing determinant (PND) of gp120 is highly unusual in the IIIB/LAV-1 strain and is not representative of those found in the majority of field isolates. We have now examined the immunogenicity of recombinant gp120 prepared from the MN strain of HIV-1 (MN-rgp120), whose PND is thought to be representative of approximately 60% of the isolates in North America. Our results show that MN-rgp120 is a potent immunogen and elicits anti-gp120 titers comparable to those found in HIV-1-infected individuals. While both MN-rgp120 and IIIB-rgp120 induced antibodies able to block gp120 binding to CD4, strain-specific and type-common blocking antibodies were detected. Finally, antibodies to MN-rgp120 but not to IIIB-rgp120 were effective in neutralizing a broad range of laboratory and clinical isolates of HIV-1. These studies demonstrate that susceptibility or resistance to neutralization by antibodies to gp120 correlates with the PND sequence and suggest that the problem of antigenic variation may not be insurmountable in the development of an effective AIDS vaccine.

Amino Acid Sequence↗
PubMed1990

Brush border enzymes in coeliac disease: histochemical evaluation.

Two hundred and ninety four duodenal and jejunal mucosal biopsy specimens from patients with coeliac disease, treated and untreated, and other conditions were examined histologically and by histochemical staining for five peptidase and three disaccharidase enzymes to determine profiles of activity. Suppression of activity paralleled the histology with the following enzymes: lactase, trehalase, brush border endopeptidase, dipeptidyl peptidase II and isomaltase. Lactase, trehalase, and brush border endopeptidase were specifically suppressed in untreated coeliac disease and were diagnostically useful. Examination of a combination of enzymes is recommended.

Adolescent↗
PubMed1989

Phenylalanine hydroxylase gene haplotypes in Polynesians: evolutionary origins and absence of alleles associated with severe phenylketonuria.

A total of 630 haplotypes for the phenylalanine hydroxylase (PAH) gene locus were established in five groups of Polynesians comprising Samoans, Tongans, Cook Islanders, Maori, and Niueans. Considerable genetic continuity was demonstrated between these widely dispersed populations, since three common haplotypes (4, 1, and 7) constituted over 95% of alleles. A control group of individuals from Southeast Asia shared the same major haplotypes, 4, 1, and 7, with Polynesians. These data provide further support for the theories of genetic homogeneity and of Asian affinities of the Polynesian precursor populations. The absence of severe phenylketonuria (PKU) in both Polynesians and Southeast Asians is consistent with the lack of PAH haplotypes 2 and 3, on which the severe PKU mutants have arisen among Caucasians.

Biological Evolution↗
PubMed1988

How do we teach pathology? The laser videodisc and computer-assisted learning.

A laser videodisc, holding 54,000 still frames per side, can be used to provide visual material of excellent quality for pathology teaching. In a collaborative project between ten pathology departments, the first pathology videodisc has recently been completed and the production of the disc is described. When used as illustrative material for computer-assisted learning programs, the videodisc offers accurate random access of still frames and allows the overlay of computer-generated graphics onto the video picture. This can be used to pre-identify every individual feature of a particular frame, and an example tutorial program is described to show how this may be used to improve the students' understanding of what they see. Details and costs are given for a workstation suitable for this application and potential future developments for this teaching method are discussed. Although objective assessment of the cost-effectiveness of interactive video in teaching pathology has yet to be undertaken, one suitably designed program can give individual tuition to many students, making this a most efficient use of teaching time.

Computer-Assisted Instruction↗
PubMed1986

Long-term tolerance of amiodarone treatment for cardiac arrhythmias.

For the 5-year period 1979 to 1983, 242 patients were followed up who had received amiodarone treatment, 156 for supraventricular tachycardia (SVT) and 86 for ventricular arrhythmias. Five patients were lost to follow-up overseas; the rest were followed to cessation of therapy, death or recent review for a mean of 24 +/- 15 months. Male/female incidence was 1.8:1 and mean age was 58 years (range 4 to 88). Half the group had impaired left ventricular function. Adverse effects were recorded in 59% of the patients and led to drug withdrawal in 26% of the total group. In contrast, unsuccessful treatment was the cause of drug withdrawal in only 5% of the patients, although an additional 25% stopped taking the drug for various reasons. Actuarial survival for the whole group, and subgroups with SVT and ventricular tachycardia/fibrillation were 66%, 74% and 52%, respectively, at 50 months. For the whole group, the actuarial probability of being alive and continuing with amiodarone therapy was only 19% at 50 months. Thus, although amiodarone was effective, few patients tolerated the drug on a long-term basis. Although amiodarone remains a valuable treatment for patients with ventricular tachycardia, its long-term effectiveness for patients with SVT is less certain.

Adolescent↗
PubMed1986

The integration of spina bifida children--are their needs being met?

After eleven years of vigorously promoting integration, the majority of Sheffield Children's Hospital spina bifida patients are now successfully integrated. A parallel study in Greater Manchester confirmed that parents, teachers and the spina bifida children are overwhelmingly in favour of integration. A large number of children were transferred from special to ordinary schools, and very few had to be transferred back to segregated schooling. The parents found substantial social and educational advantages in integration, together with good levels of involvement with their child's education. The most important areas in need of greater funding were considered to be: non-teaching support for toiletting, visiting specialists, particularly physiotherapists, and in-service education of teachers.

Adolescent↗
PubMed1985

Clinical diagnosis: a post-mortem assessment of accuracy in the 1980s.

The clinical diagnoses of a series of 400 patients dying in hospital were compared with the pathological findings at autopsy. The clinical diagnoses were precisely confirmed in only 46.75% of cases (average age 65.3 y). Potentially treatable disease was missed in 13% of patients (average age 72.7 y). The most frequent errors, both of under-diagnosis and over-diagnosis, were for pulmonary embolus, pneumonia and myocardial infarction. Over-diagnosis increased with length of hospital stay. Peritonitis and other deep-seated sepsis were surprisingly frequently missed in life. The findings closely parallel those from other units both in Britain and overseas, and suggest that there is currently a high diagnostic error rate, which varies remarkably little from one institution to another.

Adolescent↗
PubMed1984

A highly basic N-terminal extension of the mitochondrial matrix enzyme ornithine transcarbamylase from rat liver.

We have deduced the amino acid sequence of the N-terminal leader peptide of the mitochondrial enzyme ornithine transcarbamylase from a cDNA clone obtained from a rat liver cDNA library. The sequence is remarkable in being highly basic, having 4 arginine, 3 lysine and 1 histidine with no acidic residues in a total of 32 residues. The leader sequence has no extensive hydrophobic stretches, has 72% homology with the leader peptide of human ornithine transcarbamylase [1], and in terms of its basic character resembles the N-terminal extensions on a number of fungal mitochondrial [2-5] and pea chloroplast [6] proteins. Thus the basic nature of these leader peptides may constitute the signal for mitochondrial import.

Amino Acid Sequence↗
PubMed1980

19-nor analogs of adrenal steroids: mineralocorticoid and glucocorticoid receptor activity.

The effect of absence of the C-19 methyl group from five adrenal steroids has been studied in terms of their affinity for mineralocorticoid (MR) and glucocorticoid receptors (GR). In MR assays, 19-nordeoxycorticosterone and 19-norprogesterone showed 3-fold higher affinity for MR than did their respective parent steroids; 19-norcortisol had 1.5 times the affinity of cortisol for MR. In contrast, corticosterone and 19-nororticosterone showed equal affinity, and 19-noraldosterone showed less than 1% the MR activity of aldosterone. In GR assays, the absence of the C-19 methyl group from progesterone increased GR affinity 3-fold and deoxycorticosterone affinity 1.5-fold. In contrast, the other 19-nor steroids showed decreased affinity vis à vis their parent compounds (19-norcorticosterone, 30%; 19-norcortisol, 10%; 19-noraldosterone, < 1%). These findings suggest that while the 19-nor analogs of 11-deoxy steroids are consistently more active than their parent steroid, the 19-nor 11-oxygenated adrenal steroids show no predictable pattern of binding for MR or GR.

Aldosterone↗
PubMed1979

Development of large scale fractionation methods. VII. Preparation of antithrombin III concentrate.

A large scale method for preparation of antithrombin III (AT III) concentrate from plasma or from Cohn fraction IV-1 (Fr. IV-1) has been described. It consists of the following steps: (a) partial purification by precipitation of impurities with 20% polyethylene glycol (PEG) 4000; (b) isolation of AT III from the PEG supernatant by batch adsorption and elution on heparin-Sepharose at a ratio corresponding to 45 vol of plasma or 80 vol of 10% Fr. IV-1 solution to 1 vol of gel; (c) concentration and desalting of the eluted AT III on a Pellicon ultrafiltration system; (d) pasteurization of AT III concentrate by heating for 10 h at 60 degrees C in the presence of 0.5 M sodium citrate at pH 7.5; (e) removal of excess citrate by gel filtration on Sephadex G-50; and (f) sterile filtration, filling and lyophilization. The recovery by activity was 32% from a 113-liter plasma batch and 16% from a 42-kg Fr. IV-1 batch. Both AT III concentrates, derived either from plasma or from Fr. IV-1, had similar specific activity and electrophoretic purity, were nonpyrogenic and met all other FDA requirements for biologic products. Pasteurization induced changes in disc gel and isotachophoretic patterns of AT III preparations.

Adsorption↗