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Biomedical subjects

K Hart

Publications and source records attributed to K Hart.

At least 55 records · Page 3Linked to original sources
PubMed1988

Neuropsychologists' training, experience, and judgment accuracy.

It is often assumed that judgment accuracy improves as clinical training and experience increase, but the few studies on this topic within neuropsychology have yielded negative findings. In an extension of prior research, we obtained information on background training and experience from a nationally representative sample of clinical neuropsychologists and had each practitioner appraise one from among a series of 10 cases. Except for a possible tendency among more experienced practitioners to overdiagnose abnormality, no systematic relations were obtained between training, experience, and accuracy across a series of neuropsychologic judgments. Comparable results were obtained when analysis was limited to the top versus bottom 20% of the sample. This and other studies raise doubt that clinical neuropsychologists train and practice under conditions conducive to experiential learning. The potential benefits of further research on experience and judgment accuracy are discussed.

Journal Article↗
PubMed1987

The application of linkage analysis to genetic counselling in families with Duchenne or Becker muscular dystrophy.

A total of 278 families of probands with Duchenne or Becker muscular dystrophy has been ascertained and offered genetic counselling. Linkage studies have been performed in these families using polymorphic DNA markers identifying loci linked to Duchenne and Becker muscular dystrophy. The clinical features of the probands are discussed: there was marked intrafamilial resemblance in the severity of the disease. We estimate that a complete study of potential carriers in these families would require analysis of samples from approximately 1400 subjects. The results of linkage studies tended to move women's carrier risk estimates (based on CK and pedigree data) towards the extremes of the risk categories, providing a more definitive risk estimate for 81% of the women who were previously in the middle range of carrier risk probabilities. About 70% of the families had only one affected member. Linkage analysis altered carrier risk estimates in 95% of sisters and aunts of index cases, but only affected estimates of the mother's carrier risks in about 11% of isolated cases. Even where linkage studies were not helpful in elucidating carrier risks, information could usually be obtained for use in prenatal diagnosis if required. We have assessed the attitudes to pregnancy and prenatal diagnosis of women at risk of being carriers of Duchenne or Becker muscular dystrophy and report 17 pregnancies in these women.

Amniocentesis↗
PubMed1987

Thromboxane synthetase inhibition in primary pulmonary hypertension.

Thromboxane synthetase inhibitors have been shown to reduce thromboxane, a potent vasoconstrictor, and increase prostacyclin, a potent vasodilator, in normal subjects. We evaluated the acute and chronic (three months) effects of the thromboxane synthetase inhibitor CGS13080 administered 200 mg every six hours on the resting hemodynamics in ten patients with primary pulmonary hypertension (PPH), and on their response to 20 mg of nifedipine given sublingually before and after the thromboxane synthetase inhibitor treatment. It was concluded that one can modulate the levels of endogenous thromboxane and prostacyclin in patients with primary pulmonary hypertension using a thromboxane synthetase inhibitor. Although the thromboxane synthetase inhibitor alone produced only modest hemodynamic changes over time, the addition of nifedipine was able to produce a further lowering of pulmonary artery pressure and pulmonary vascular resistance.

Adult↗
PubMed1986

Antinuclear antibodies in primary pulmonary hypertension.

The association of positive antinuclear antibodies with the clinical and hemodynamic features of 43 patients with primary pulmonary hypertension and 16 patients with secondary pulmonary hypertension was investigated. Each patient had determinations of antinuclear antibodies using a KB cell substrate immunofluorescent test. Of the patients with primary pulmonary hypertension, 40% had positive antinuclear antibodies at titers of 1:80 dilutions or greater. There were no differences between patients with primary pulmonary hypertension and positive antinuclear antibodies compared with those with negative antinuclear antibodies in relation to clinical or hemodynamic status. A 6% incidence rate of antinuclear antibodies was found in patients with secondary pulmonary hypertension, similar to that in the normal population. The clinical, hemodynamic, serologic and histologic similarity between patients with primary pulmonary hypertension and those with unexplained pulmonary hypertension associated with collagen vascular disorders suggests that primary pulmonary hypertension in some patients may represent a collagen vascular disease confined to the lungs. The frequency of positive antinuclear antibody tests would place primary pulmonary hypertension between rheumatoid arthritis and scleroderma in the spectrum of collagen vascular diseases. Further studies are necessary, however, before one might expect that immunosuppressive therapy would be beneficial to these patients.

Adult↗
PubMed1986

Control of expression of an integrated Rous sarcoma provirus in rat cells: role of 5' genomic duplications reveals unexpected patterns of gene transcription and its regulation.

Rat cells transformed by Rous sarcoma virus frequently contain duplications of viral (and sometimes cellular) DNA 5' to the integrated provirus, suggesting that such rearrangements favor provirus expression. In one cell line, A11, the duplication includes the viral src gene and proviral sequences that flank it. We examined three possible roles for this structure. Since the proviral v-src gene transformed recipient cells upon DNA transfer and was the major template for v-src transcription in A11 cells, the presence of v-src in the duplication is presumably not necessary for transformation. Since the size and structure of transcripts from the proviral v-src gene in A11 cells were conventional, the duplication does not facilitate transformation by providing a novel transcriptional strategy. Thus, we favor the concept that the duplication either attenuates a negative effect of flanking elements at the host chromosome integration site or augments the positive regulation of conventional provirus expression or both. Gene transfer and transcription analyses with both genomic and cloned DNA showed that the mechanisms of such regulatory phenomena are complex. Identical sequences in the provirus and the 5' duplication displayed different patterns of expression in A11 cells that could be disrupted in segments of cloned DNA. Among the elements that influenced such expression were sequences from the gag-pol region of the provirus.

Animals↗
PubMed1986

The screening of Duchenne muscular dystrophy patients for submicroscopic deletions.

We have probed the DNA of 156 Duchenne muscular dystrophy (DMD) patients, representing 140 kindreds, with cloned DNA sequences derived from Xp21 and known to show deletions in some DMD patients. Sixteen cases showed a deletion, as defined by lack of hybridisation to one or more of the four probes used. However, two of these cases were brothers, so 15 independent deletions (10.7%) are represented. The deletion map is compatible with the suggested order for the sites of the probes used in the study, that is, telomere----pERT87.15----pERT87.8----pERT87.1----pX J1.1----754----centromere. Further mapping of these deletions and characterisation of the deletion breakpoints should facilitate more accurate molecular localisation of the gene or genes which, when mutated, are responsible for causing DMD.

Chromosome Deletion↗
PubMed1986

Linkage studies in Duchenne and Becker muscular dystrophies.

We have studied the inheritance of four cloned DNA sequences which recognise restriction fragment length polymorphisms on the short arm of the X chromosome in families with Becker and Duchenne muscular dystrophy. We have confirmed linkage of two probe loci to the disease loci and have combined our results with those previously published to give a maximum lod score of 11.642 at a recombination fraction of 0.15 for DXS41 (probe 99.6), and a maximum lod of 15.84 at a recombination fraction of 0.15 for DXS84 (probe 754). Linkage of these diseases to the loci defined by the pERT87 probes and probe pXJ1.1 has also been studied, giving maximum lod scores of 8.634 and 5.118 at recombination fractions of 0.02 and 0.00 respectively. The information obtained using these polymorphic DNA markers, combined with pedigree and CK data, can be used to give more accurate genetic counselling to women at risk in Becker and Duchenne families.

DNA↗
PubMed1986

Primary pulmonary hypertension: radiographic and scintigraphic patterns of histologic subtypes.

The chest radiograph and perfusion lung scans were evaluated in 39 consecutive patients with primary pulmonary hypertension to see if these noninvasive methods could distinguish among the histologic subtypes. Chest radiographs were categorized as having either normal lung fields or increased bronchovascular markings. Blood flow on lung scans was graded as normal or as having diffuse, nonsegmental, patchy abnormalities. These patterns were then correlated against pathologic specimens obtained from 19 patients, which were graded on vascular changes and microthrombi. Plexogenic arteriopathy was characterized by a normal chest radiograph and normal distribution of tracer on lung scan. Thromboembolism was characterized by a normal chest radiograph but patchy distribution of tracer on lung scan. Pulmonary veno-occlusive disease was characterized by increased bronchovascular markings on chest radiograph as well as patchy distribution of tracer on lung scan. Distinguishing patients on the basis of their histologic characteristics may be important so that vasodilators or anticoagulants can be selected as therapy.

Adult↗
PubMed1984

Etodolac, aspirin, and gastrointestinal microbleeding.

The effects of etodolac, a new nonsteroidal anti-inflammatory drug, on gastrointestinal (GI) microbleeding were quantitatively assessed in two studies in healthy adult men. The first was a two-group, open-label, parallel comparison of etodolac, 600 mg/day, aspirin, 2600 mg/day, and placebo in 20 subjects; the second was a four-group, double-blind, parallel comparison of etodolac, 600, 800, and 1200 mg/day, aspirin, 2600 mg/day, and placebo in 41 subjects. Subjects in both studies received a single-blind placebo on days 1 through 7, either etodolac or aspirin on days 8 through 14, and a single-blind placebo on days 15 through 19. GI blood loss (milliliters per day) was estimated by the radiolabeled (51Cr) erythrocyte method and was based on daily radioactivity counts of stool specimens and regression-estimated daily blood radioactivity. Etodolac, 600 mg/day, induced no significant GI blood loss at any time during the experiments, nor was there significant blood loss after 800 and 1200 mg/day in experiment 2. Blood loss was noted after aspirin in both.

Acetates↗
PubMed1984

Acute lower respiratory tract infections in children: possible criteria for selection of patients for antibiotic therapy and hospital admission.

Acute lower respiratory tract infections are a common cause of morbidity and mortality in children in the less developed countries. Considering the urgent need for rational protocols for the management of these infections in children and how little is known about the clinical signs that might predict the need for antibiotic therapy in a primary health care setting, a prospective study of the clinical signs in 200 paediatric outpatients presenting with a cough, 100 age-matched controls without cough, and 50 children admitted to hospital with pneumonia was carried out.In children with cough, a respiratory rate greater than 40 or 50 per minute (or a qualitative impression of tachypnoea) is probably the best indicator of the need for starting antibiotic treatment by primary health workers. The presence of fever appeared to be a poor guide to the need for antibiotic therapy. The presence of chest indrawing is, however, a reliable indication that a child with cough should be admitted to a health centre or a hospital. Further prospective studies are needed to determine the ability of these clinical signs to predict the course of these infections.

Acute Disease↗
PubMed1980

Corynebacterium parvum: immunomodulation in local bacterial infections.

Inoculation with Corynebacterium parvum 14 days before bacterial challenge produced protection against murine-simulated surgical wound infection with Escherichia coli to the same degree as had been provided by Bacillus Calmette-Guerin pretreatment. Simulated surgical wound infection induced by Staphylococcus aureus in mice followed a much more variable course; bacterial growth was depressed 7 days after C. parvum inoculation and was equivocal at a 14 day interval. Unlike E. coli infection modified by C. parvum or BCG, bacterial growth was significantly enhanced when the interval between C. parvum inoculation and S. aureus challenge was 20 or 28 days. Explanations for these differences and their possible clinical relevance are discussed.

Animals↗
PubMed1976

Sustained haemodynamic action of nitroglycerin ointment.

Intravenous vasodilators have been shown to improve the haemodynamic status of patients in congestive heart failure. However, neither intravenous nor sublingual preparations are suitable for chronic administration or use in ambulatory patients. In this study, nitroglycerin ointment bas administered to 11 patients in congestive heart failure. Mean pulmonary wedge and arterial pressures, as well as systemic blood pressures and heart rate were then monitored for 2 to 5 hours and compared with baseline values. Pulmonary wedge and arterial pressures, as well as systemic systolic arterial pressure, decreased significantly at 15 minutes after application and remained depressed for up to 5 hours. Systemic diastolic pressures fell significantly at 30 minutes and also remained significantly reduced for up to 5 hours. Thus, nitroglycerin ointment may be suitable for chronic vasodilator therapy of congestive heart failure.

Adult↗