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Biomedical subjects

G Nelson

Publications and source records attributed to G Nelson.

At least 91 records · Page 5Linked to original sources
PubMed1989

Development of a 12 element annular array transducer for realtime ultrasound imaging.

While the recent proliferation of ultrasound scanners based on annular array transducers has attracted widespread attention, very little published information is available on the physics, design criteria, and signal processing aspects of these instruments. In this paper, the first of a two part report, we describe the development and characterization of an annular array transducer for realtime medical imaging. Theoretical modeling of the pulsed fields of annular arrays is used to study and optimize array parameters. The factors which affect resolution and contrast in imaging--beam width, sidelobe levels, number of annuli, depth of field, and delay quantization--are discussed. A 12 element, 4.5 MHz, 30 mm design is adopted. Theoretical predictions showed excellent agreement with device measurements over a range of f-numbers (local/length/diameter) from f/1 to f/6.7 (30 to 200 mm range). Focusing to f/1 is an important advance in the state-of-the-art. A two transmit zone, dynamic receive configuration of array operation to exploit the f/1 focusing ability is proposed for realtime imaging.

Equipment Design↗
PubMed1989

Bronchoalveolar lavage plasmacytosis in a patient with a plasma cell dyscrasia.

A patient with serum monoclonal gammopathy, Bence-Jones proteinuria, and bone marrow plasmacytosis underwent fiberoptic bronchoscopic study for evaluation of interstitial lung disease. Bronchoalveolar lavage fluid contained 47 percent plasma cells, which were monoclonal by immunoperoxidase staining. This is the first time BAL plasmacytosis has been demonstrated in a patient with a plasma cell dyscrasia.

Aged↗
PubMed1988

Evaluation of a social problem-solving skills program for third- and fourth-grade students.

The effects of a social problem-solving (SPS) training program for entire classrooms of third- and fourth-grade children were examined in two studies. In the first study, experimental children showed significantly greater improvement in knowledge and performance of SPS skills than control children. However, both positive and negative effects of the intervention (varying by classroom) were found on measures of behavioral adjustment, self-efficacy, and peer acceptance at a 6-month follow-up. The second study compared two different intervention strategies: (a) SPS training with teacher-student dialoguing, peer pairing, and self-monitoring, and (b) SPS training with dialoguing only. It was found that children in both the experimental and control groups improved significantly in performance of SPS skills but no differences between the groups were found for changes in behavioral adjustment, self-efficacy, and peer acceptance. The limitations of cognitively mediated interventions for young children were discussed.

Affect↗
PubMed1988

The relationship between long-term psychiatric clients' psychological well-being and their perceptions of housing and social support.

This research tested hypotheses derived from motivation-hygiene theory that housing and social support would be differentially related to long-term psychiatric clients' Positive Affect and Negative Affect. The participants were 89 people between the ages of 18 and 65, who had been hospitalized for psychiatric problems at least twice and who had been diagnosed as schizophrenic, chronic depressive, or manic-depressive. Results indicated that the number of Housing Concerns was positively correlated with Negative Affect but not Positive Affect. Support Satisfaction was negatively correlated with Negative Affect, and Frequency of Support was positively correlated with Positive Affect. Interactions between the housing variable and Network Size were found for both Positive Affect and Negative Affect, thus supporting the stress-buffering hypothesis. The findings provided mixed support for motivation-hygiene theory.

Adult↗
PubMed1988

Influence of mastectomy technique on sex steroid receptor analysis.

Accurate analysis of hormone receptors in breast carcinoma is critical from prognostic and therapeutic standpoints. Controversy exists over whether there is receptor decay when specimens are obtained upon completion of, rather than prior to, mastectomy. In addition, the effect of mastectomy technique on receptor concentration has not been addressed. Twenty patients with breast carcinoma had biopsy specimens taken prior to and upon completion of modified radical mastectomy. Ten had axillary dissection followed by mastectomy (Group A). The others had mobilization of the breast before axillary dissection (Group B). The estrogen receptor concentration was higher in 14 of 20 premastectomy specimens. All 10 patients in Group B had positive receptors before mastectomy; 5 were negative after mastectomy. All seven patients in Group A with positive premastectomy receptors remained so postmastectomy. We concluded that if a tumor specimen for receptor analysis is not obtained prior to modified radical mastectomy, axillary dissection should precede breast mobilization.

Axilla↗
PubMed1988

Intraprostatic spermatozoa.

Spermatozoa have not previously been described within the prostate gland. Nine of one hundred prostates of nonhospitalized males obtained from autopsy during the course of medicolegal death investigation were found to contain spermatozoa. The potential role of spermatozoa in the pathogenesis of corpora amylacea/calculi formation, granulomatous inflammation, local antigenic stimulation, and carcinogenesis is considered.

Adolescent↗
PubMed1988

Limitation of myocardial infarction by early infusion of recombinant tissue-type plasminogen activator.

In a double-blind randomized trial involving five Sydney hospitals and the city ambulance paramedical service, 145 patients with a first evolving myocardial infarction and with onset of pain less than 2.5 (mean 1.9 +/- 0.5 [SD]) hr previously were allocated to intravenous infusion of 100 mg recombinant tissue-type plasminogen activator (rt-PA) or placebo over 3 hr. The groups at entry were similar. At assessment 21 days later, left ventricular ejection fraction measured both by contrast and radionuclide ventriculography was higher in the rt-PA compared with the placebo group (61 +/- 13%, n = 64, vs 54 +/- 14%, n = 62, contrast, 2p = .006; 52 +/- 13%, n = 66, vs 48 +/- 13%, n = 62 isotope, 2p = .08). This indicates limitation of myocardial infarction by rt-PA.

Adult↗
PubMed1988

Evaluation of community-based rehabilitation in Punjab, Pakistan: I: Use of the WHO manual, 'Training disabled people in the community'.

The WHO community-based rehabilitation programme has been tested in a village and a slum area in Pakistan. House-to-house surveys by physicians identified medical diagnoses and impairments and handicaps according to the ICIDH. Volunteer local supervisors from the communities were taught to identify and train disabled persons according to the CBR manual. The effect of training was evaluated after 1-2 years by an occupational therapist, using questions from the same manual. Of the 82 persons followed up, 80% showed improvement in function. The prevalence of disablement identified by the local supervisors and of handicap identified by a physician agreed well, and was of the order of 5%.

Community Health Services↗
PubMed1988

Evaluation of community-based rehabilitation in Punjab, Pakistan: II: The prevalence of diseases, impairments, and handicaps.

A health survey using the impairment and handicap classifications from the ICIDH was carried out in conjunction with a study of the WHO community-based rehabilitation programme in a village and a slum area in Pakistan. The prevalence of handicaps defined in this way was about half that of impairments, the most common handicaps being with mobility, occupation, and social integration. There was a slightly higher degree of handicap in the village. In both areas diseases of the musculoskeletal system, the ear, and the respiratory tract were common, but the frequency of infectious, respiratory, endocrine, blood, and digestive diseases was higher in the slum area.

Community Health Services↗
PubMed1988

School health education to prevent the spread of AIDS: overview of a national programme.

The ultimate goal of CDC's School Health Education to Prevent the Spread of AIDS programme is to reduce the incidence of HIV infection among school-aged youth. Working objectives that integrate programme research and development activities are listed in the opposite Table. In 1982 it was estimated that of the 4.6 billion people in the world, about one billion were school-aged, and about 870 million of these youth were enrolled in schools. WHO, UNESCO, and the International Union for Health Education have recognized that schools could provide a critical means for ensuring that young people throughout the world understand the global AIDS pandemic they face, and what they can do to protect themselves, the families for which they will become responsible, and the communities in which they will reside. But if schools are to provide effective AIDS education, they will require the commitment and active collaboration of education and health leaders in local, national, and international agencies.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Extracellular acid and alkaline proteases from Candida olea.

Candida olea 148 secreted a single acid protease when cultured at acidic pH. In unbuffered medium, the culture pH eventually became alkaline and a single alkaline protease was produced. This was the only proteolytic enzyme produced when the organism was grown in buffered medium at alkaline pH. Both proteolytic enzymes were purified to homogeneity (as assessed by SDS-PAGE). The Mr of the acid protease was 30900, the isoelectric point 4.5; optimum activity against haemoglobin was at 42 degrees C and pH 3.3. This enzyme was inactivated at temperatures above 46 degrees C and was inhibited by either pepstatin and diazoacetyl-norleucine methyl ester but was insensitive to inhibition by either 1,2-epoxy-3-(p-nitrophenoxy)-propane or compounds known to inhibit serine, thiol or metallo proteases. The acid protease contained 11% carbohydrate. The alkaline protease had an Mr of 23400 and isoelectric point of 5.4. The activity of this enzyme using azocoll as substrate above 42 degrees C and was inhibited by phenylmethyl-sulphonyl fluoride and irreversible inactivated by EDTA. The enzyme was also partially inhibited by DTT but was insensitive to either pepstatin or p-chloromercuribenzoic acid.

Aspartic Acid Endopeptidases↗
PubMed1986

Hospital deaths in a high risk obstetric population: Karawa, Zaire.

Three thousand four hundred thirteen consecutive deliveries at a rural hospital in Zaire are examined. 85% of patients had goiters and 5% were cretins. Twenty maternal deaths occurred, or 5.9 per 1000 deliveries. Risk factors for maternal death included late presentation, advanced age (greater than or equal to 35 years), no education and presence of goiter or cretinism. Ninety percent of women who died were in critical condition at admission, 45% had labored greater than or equal to 48 h and 70% had uterine rupture.

Adolescent↗
PubMed1985

Circulatory effects of intravenous and oral acebutolol in acute myocardial infarction.

The hemodynamic dose-response effects of intravenous (25 and 50 mg) and oral (200 and 400 mg) acebutolol were compared in a randomized between-group study in men within 17 hours of an acute uncomplicated myocardial infarction. Six subjects were evaluated in each of the four groups. After a 1-hour control period, hemodynamic variables and plasma drug concentrations were determined at 15 (intravenous therapy only), 30, 60, 90, 120, and 240 minutes after dosing. At the doses studied, hemodynamic dose-response effects were not evident after either intravenous or oral acebutolol. In all groups acebutolol reduced systolic and mean systemic arterial pressure, heart rate, cardiac output, and stroke volume. Pulmonary artery occluded pressure and systemic vascular resistance were transiently increased. Maximum changes developed between 15 and 30 minutes after intravenous dosing and between 1 and 2 hours after oral dosing. However, there were substantial reductions in cardiac output (-0.7 L/min/m2; P less than 0.05) by 30 minutes after oral dosing. Effects lasted for 2 hours after intravenous dosing and for 4 hours after oral dosing. Our data confirm the hemodynamic safety of acebutolol after acute myocardial infarction. The relevance of the time-dependent hemodynamic differences between intravenous and oral initiation of beta-blockade to the overall goal of reducing myocardial oxygen requirements after acute coronary artery occlusion merits closer examination.

Acebutolol↗
PubMed1984

Stress and social support: the burden experienced by the family of a mentally ill person.

The present research examined the burden experienced by the families of a mentally ill person and the relationship between this stress and social support. The participants were 56 parents of a schizophrenic person who were members of a self-help group for the families of psychiatric patients. Results indicated that low levels of burden were associated with small dense social networks, satisfaction with support received, satisfaction with the support from the self-help group, and spouse involvement with the patient. Qualitative data revealed that the stress encountered was chronic in nature, that the families lacked relevant information, and that the self-help group was beneficial. Implications for future research were discussed.

Family↗
PubMed1984

Dose-response effects of cardioselective beta blockade in coronary artery disease.

The hemodynamic dose-response effects of intravenous acebutolol, a cardioselective beta-adrenoceptor antagonist with intrinsic sympathomimetic activity, were evaluated in 12 male subjects with angiographically confirmed coronary artery disease. At rest after a saline solution control period, four doubling intravenous boluses of acebutolol (logarithmic cumulative dosage of 20, 40, 80, and 160 mg) were injected at 4-min intervals; hemodynamic variables were recorded 2 to 4 min after each injection. Hemodynamic effects of the drug during steady-state exercise were evaluated by comparison of a control exercise period with observations made at the same workload (25W to 50W) after the maximum cumulative dose (160 mg). After the four intravenous boluses, plasma acebutolol concentrations rose in log-linear fashion and levels achieved (0.6 to 3.5 micrograms/ml) were within the range at which substantial pharmacodynamic activity is usually present (i.e., 0.02 to 0.2 microgram/ml). Compared with control measurements at rest after saline solution injection, these plasma concentrations of acebutolol resulted in a quadratic reduction in heart rate (maximum delta HR, -4 bpm) and a linear increase in pulmonary artery occluded pressure (maximum delta PAOP, +3 mm Hg) without change in systemic arterial pressure. There was a small reduction in cardiac output (delta cardiac index [CI], -0.2 l/min/m2). During steady-state supine bicycle exercise, there were significant reductions in systolic blood pressure (delta SBP, -15 mm Hg, or 9%) HR (-9 bpm or -9%), cardiac output (delta CI, -1.0 l/min/m2, or -18%), and increase in PAOP (+8 mm Hg, or +38%).(ABSTRACT TRUNCATED AT 250 WORDS)

Acebutolol↗
PubMed1984

Endemic infantile hypothyroidism in a severe endemic goitre area of central Africa.

Thyroid function and exposure to dietary goitrogenic factors (iodine deficiency and thiocyanate overload) were studied at birth and from birth to 7 years in 200 neonates and 347 children living in the severe endemic goitre area of Ubangi, Northern Zaire. Serum T4 was at the lower limit of normal at birth (104 +/- 4 nmol/l) and stayed at that level during the first year of life (123 +/- 9) (NS), but decreased to 75 +/- 8 (P less than 0.001) at 2-4 years and to 62 +/- 6 (P less than 0.001) at 5-7 years of age. Mean serum FT4 decreased from 10.4 +/- 0.9 pmol/l during the first year to 8.2 +/- 1.0 (NS) at 2-4 years (NS) and to 7.7 +/- 0.9 (P less than 0.05) at 5-7 years. Mean serum TSH was 10.4 (8.4-12.9) mU/l (geometric mean +/- 1 SEM) during the first year, 10.1 (7.5-13.7) (NS) at 2-4 years and 24.3 (18.5-31.9) (P less than 0.05) at 5-7 years. Mean serum T3 was 3.23 +/- 0.12 nmol/l during the first year and remained stable thereafter. The frequencies of low T4 (T4 less than 77 nmol/l), high TSH TSH (TSH greater than 50 mU/l), and low T4 and T3 (T3 less than 1.69 nmol/l) were twice as high at 5-7 years as in the first year (respectively 65%, 42% and 15%). The urinary iodide concentration of the children was stable and low throughout the study period. By contrast, serum thiocyanate concentration which was high at birth (129 +/- 5 mumol/l) decreased to normal values between 3 and 12 months of age and increased again during and after weaning (1 to 3 years of age) to reach a value of 138 mumol/l which was comparable to that observed in adults in the same area. Thiocyanate concentration was high (133 +/- 7 mumol/l) in the mothers' serum but low in the mothers' milk (57 +/- 3 mumol/l) (P less than 0.001). Multivariate analysis showed that both iodine deficiency and thiocyanate overload were explanatory factors of the serum levels of T4, FT4 and TSH in children. In conclusion, our results show that infantile hypothyroidism is much more frequent at 5-7 years of age than at birth or during the first year of life. The deterioration in thyroid function during and after weaning is linked to persistent iodine deficiency accompanied by an increase in thiocyanate overload. The variability in the age of onset, the severity, and the duration of infantile hypothyroidism might explain the wide range of psychomotor and physical abnormalities observed in a large proportion of subjects in this area.

Adolescent↗