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Biomedical subjects

R Robertson

Publications and source records attributed to R Robertson.

At least 73 records · Page 4Linked to original sources
PubMed1991

Propranolol fails to lower the increased blood pressure caused by cold air exposure.

Cold air exposure stimulates a rise in mean arterial blood pressure (MAP) and plasma norepinephrine (NE). The specific contribution of the beta-adrenergic receptor to this pressor response is unknown. Therefore, we pretreated 12 normal men with placebo or a bradycardia-inducing amount of propranolol prior to exposing them to either 25 degrees C or 4 degrees C air. At 25 degrees C, propranolol pretreatment lowered heart rate (HR) and MAP. When we compared changes in MAP after their respective 30-min exposure at 25 degrees C and 4 degrees C, the cold elevated MAP by 18.4 +/- 1.5 mm Hg in subjects pretreated with propranolol compared with 13.0 +/- 2.5 mm Hg in subjects pretreated with placebo. Fingertip skin temperature (Tfing) measured at 4 degrees C, 9.5 +/- 0.8 degrees C in propranolol-pretreated subjects was lower than the 11.1 +/- 0.7 degrees C with that of placebo. Plasma NE increased equally during cold exposure with both placebo and propranolol pretreatment. We conclude that the beta receptor plays a minor role in generating the pressor response to cold air. Therefore, the effectiveness of acute administrations of propranolol for maintaining normotension in subjects exposed to cold environments may be attenuated.

Blood Pressure↗
PubMed1991

Intraarterial cisplatin in the management of stage IIB osteosarcoma in the pediatric and adolescent age group.

Sixty patients with extremity osteosarcoma were treated with intraarterial cisplatin. This was followed by surgical resection (amputation or limb salvage) and postoperative adjuvant chemotherapy utilizing two different protocols. Seventy-five percent of patients achieved an initial response. Overall disease-free survival was 58%. The number of patients treated with limb-salvage surgery gradually increased to the extent that 80% of newly-registered patients achieved a response and were subjected to limb salvage. Disease-free survival was 48% in amputation and 68% in limb salvage. The only factors found to have prognostic significance in determining disease-free survival were extent of tumor destruction induced by preoperative chemotherapy and tumor size.

Adolescent↗
PubMed1990

Pediatric osteosarcoma: therapeutic strategies, results, and prognostic factors derived from a 10-year experience.

Ninety-eight pediatric patients were treated with three separate protocols (Treatment and investigation of Osteosarcoma [TIOS] I, II, and III) and 47 developed recurrent disease (metastases and/or local recurrence). Actuarial overall disease-free survival (hereafter designated survival) was 43%. Over 90% of the patients were treated initially with preoperative intraarterial cisplatin (CDP). Postoperative chemotherapeutic regimens comprised high-dose methotrexate with leucovorin rescue (MTX-CF), Adriamycin [( ADR] doxorubicin; Adria Laboratories, Columbus, OH), and cyclophosphamide. Primary definitive treatment comprised amputation or limb salvage (TIOS I and TIOS III). Patients treated with preoperative CDP and surgery (TIOS I and III) had a 62% survival. Patients in TIOS II refused surgical extirpation; they were treated exclusively with chemotherapy and had a 23% survival. Survival in patients treated with amputation was 55% and limb salvage 58%. Prognostic factors considered significant in relation to development of pulmonary metastases comprised tumor burden (P = .04) and the percentage of tumor necrosis induced by preoperative chemotherapy (P = .01). Histopathologic subtype was marginally significant: chondroblastic was more favorable as opposed to osteoblastic (P = .05). These findings are compared with results and prognostic factors published in the literature.

Child↗
PubMed1990

Accuracy and reliability of the Caltrac accelerometer for estimating energy expenditure.

The Caltrac accelerometer is designed to assess energy expenditure during normal activity. The aims of the present study were (a) to determine the interinstrument and intersession reliability of the Caltrac and (b) to validate these instruments with measures of oxygen uptake (VO2) and determine whether Caltracs accurately reflect differences in energy expenditure due to sex, body weight, and speed. Caltracs were found to have very good interinstrument and intersession reliability and to accurately reflect differences in expenditure due to sex, weight, and speed. However, Caltracs consistently over-estimated energy expenditure by an average of 9-13%. The absolute percent error (percent error without consideration of the sign) of the Caltrac was greater, averaging 23%. The correlations between Caltrac and VO2 averaged 0.68-0.74. Thus, the Caltracs seem well suited for studies of activity level of groups, but may be less useful in estimating an individual's activity.

Adult↗
PubMed1990

Effects of collection methods and storage on the in vitro stability of canine plasma catecholamines.

Norepinephrine (NE) and epinephrine (EPI) collected from dogs were sequentially and temporally measured in blood and plasma at 24 C. Heparin and EDTA anticoagulants, in combination with reduced glutathione and EDTA as a preservative, were also compared. Norepinephrine and EPI concentrations were measured by high-pressure liquid chromatography with electrochemical detection. In heparinized plasma, NE and EPI concentrations were relatively stable in the absence or presence of preservative after 24 hours at 24 C. In EDTA plasma, NE and EPI values were less stable when compared with those in heparinized samples. Norepinephrine concentrations in EDTA plasma without preservative decreased by 163.2 +/- 8.88 pg over 24 hours, compared with an 86.6 +/- 7.92 pg loss of NE in heparinized plasma. The degradation of EPI in EDTA plasma without preservative was also twofold greater, compared with that in heparinized plasma. Addition of preservative had no stabilizing effect on NE or EPI in heparinized or EDTA plasma. During long-term storage at -70 C, plasma NE and EPI values decreased less than 0.6 and less than 0.1 pg/d, respectively. Norepinephrine and EPI values were stable in heparinized blood for 6 hours but decreased to less than 25% and less than 6% of initial base line values, respectively, when plasma separation was delayed 24 hours.

Animals↗
PubMed1989

Auditory function in pediatric osteosarcoma patients treated with multiple doses of cis-diamminedichloroplatinum(II).

Serial auditory evaluations were performed in 54 pediatric patients (5 to 18 yr) treated with cis-diamminedichloroplatinum(II) for osteosarcoma. Each course of cis-diamminedichloroplatinum(II) comprised 150 mg/m2 and was administered initially at two weekly intervals for seven courses (3 mo) and subsequently at three monthly intervals for 15 to 21 mo. Overall, 604 courses were administered, and observations were conducted from diagnosis to 6 yr. Bilateral hearing loss was detected in all patients. The loss varied from mild (20 to 40 dB) to profound (greater than 90 dB). Initial losses occurred in the higher frequencies and were also greater at these frequencies. Significant loss was first observed after 300 mg/m2 for frequencies over 4000 Hz and gradually shifted to incorporate the lower frequencies. Hearing loss was permanent.

Adolescent↗
PubMed1989

Effect of cumulative courses of intraarterial cis-diamminedichloroplatin-II on the primary tumor in osteosarcoma.

Preoperative chemotherapy with intraarterial cis-diamminedichloroplatin-II (CDP) and mannitol diuresis was administered to the primary tumor in 42 patients with osteosarcoma. The dose was 150 mg/m2 and more than 90% of the infusions were administered during a 2-week period. On occasion this period was extended to 3 weeks because of temporary renal insufficiency or logistical circumstances. Definitive surgical specimens were prepared by means of an arteriogram-directed plane of dissection with mapping and random sections. Histologically, tumor destruction was evaluated in terms of necrosis, inflammatory response, and fibrovascular regeneration. Quantification of the percent of tumor necrosis was as follows: less than 40% (consistent with spontaneous necrosis and/or no chemotherapy effect); 40% to 60% (possible chemotherapy effect); 60% to 90% (chemotherapy effect--partial response); and 90% to 100% (complete response). Therapeutic efficacy also was correlated with the number of CDP courses (one to three, four to five, and six to seven) and tumor subtype. Significant therapeutic effect (greater than 60% destruction) was observed with four or more CDP courses (one of nine tumors [one to three courses] versus 26 of 33 tumors [four to seven courses] [P = 0.01]). More than 60% of the tumor destruction was observed in the following subtypes: osteoblastic (22 of 28), fibroblastic (three of six), and telangiectatic (two of five). These data demonstrate that four or more courses of intraarterial CDP are required to achieve optimum effects and that osteoblastic osteosarcoma is highly responsive.

Cisplatin↗
PubMed1989

Transmission of HIV to heterosexual partners of infected men and women.

Future heterosexual spread of HIV will in part depend on the efficiency of transmission from men to women and from women to men. We studied seventy-eight female sexual partners of men infected with HIV and 18 male sexual partners of infected women. Participants were interviewed concerning sexual practices, use of contraception and other risk factors for HIV infection. Fifteen out of 78 (19.2%) female partners and one out of eighteen (5.5%) male partners were seropositive for HIV antibody. All couples had practised vaginal intercourse. Seropositive female partners did not differ significantly from seronegative partners with regard to length of relationship, number of acts of vaginal intercourse, other sexual practices, stage of clinical disease in the index case, or numbers of other sexual partners in the last five years. In two women, seroconversion was documented after one act of unprotected sexual intercourse. The majority of infected female partners (eight out of 15) had sexual relationships with men who were asymptomatic and did not practice anal intercourse. Biological factors such as variability in infectivity of the index case and susceptibility of the contact, as well as behavioural variables may be important in determining transmission.

Adolescent↗
PubMed1989

Factors affecting the job satisfaction of respiratory therapists who work in adult general and critical care: a multivariate study.

UNLABELLED: The development of an expanded understanding of employees' reaction to their job may be important for improvement in the quality of work life and of services rendered. We sought to determine the factors, or rewards, that significantly affect respiratory therapists' job satisfaction. METHOD: Questionnaires designed to elicit responses related to job satisfaction and demographic information were mailed to a random sample of registered respiratory therapists in 9 southeastern states. The Job Descriptive Index (JDI) was used to measure facets of and total job satisfaction. The independent variables used were: Satisfaction with Work on the Job, Supervision, Promotion Opportunities, Pay, and People on the Job. RESULTS: Satisfaction with Work on the Job (p = 0.0001, F = 39.1) and with Supervision (p = 0.005, F = 8.48) were the only variables that significantly affected the job satisfaction scores of respiratory therapists. CONCLUSION: Because satisfaction with work on the job and supervision seem to be rewards therapists consider important, managers need to evaluate those factors in their own organization in relation to their possible impact upon staff members.

Critical Care↗
PubMed1989

Isokinetic testing in young nonathletic able-bodied subjects.

Isokinetic strength testing has been widely used to assess athletic populations. The purpose of this study was to measure isokinetic strength in nonathletic able-bodied subjects to provide a subsequent comparison with nonathletic injured patients. Using a standard isokinetic protocol, with continuous verbal encouragement, a single investigator tested 16 women and nine men aged 20 to 30 years on an isokinetic dynamometer. Subjects had minimal athletic experience, and none were varsity performers. Peak torque as a percentage of body weight was statistically greater for men than for women in most joints tested both at 60 degrees and 180 degrees per second. The ratio of the last five to the first five of 25 repetitions at 180 degrees/second (Endurance Ratio = ER) rarely (ie, 5/154 tests) fell below the commonly accepted value of 50%. Many subjects had an endurance ratio of 100% or greater (range 4% to 171%). Peak torques were well below and endurance ratios well above those published for similarly aged athletes. The results suggest that before isokinetic testing is considered as a possible way to distinguish malingerers among injured patients, normal values in an age-matched, nonathletic, working population should be clearly defined. The endurance ratio may reflect the level of athletic training or the level of vigorous participation in an exercise program.

Adult↗
PubMed1988

Rett syndrome: EEG presentation.

Rett syndrome, a degenerative neurological disorder of girls, has a classical presentation and typical EEG findings. The electroencephalograms (EEGs) of 7 girls whose records have been followed from the onset of symptoms to the age of 5 or more are presented. These findings are tabulated with the Clinical Staging System of Hagberg and Witt-Engerström (1986). The records show a progressive deterioration in background rhythms in waking and sleep. The abnormalities of the background activity may only become evident at 4-5 years of age or during stage 2--the Rapid Destructive Stage. The marked contrast between waking and sleep background may not occur until stage 3--the Pseudostationary Stage. In essence EEG changes appear to lag behind clinical symptomatology by 1-3 years. An unexpected, but frequent, abnormality was central spikes seen in 5 of 7 girls. They appeared to be age related and could be evoked by tactile stimulation in 2 patients. We hypothesize that the prominent 'hand washing' mannerism may be self-stimulating and related to the appearance of central spike discharges.

Apraxias↗
PubMed1988

Comparison of arm and leg ergometry in patients with moderate chronic obstructive lung disease.

Exercise testing is traditionally performed with leg exercise on either a treadmill or a bicycle ergometer. Many of these tests are terminated before dyspnoea occurs because of leg fatigue, arthritic pain, or claudication. A study was carried out to determine whether arm ergometry testing might serve as an alternative method to leg testing in eight patients with chronic obstructive lung disease. The patients had mild to moderate dyspnoea on exertion and required bronchodilator treatment. They had smoked an average of 62 pack years and had a mean FEV1 of 1.88 l. Arm and leg ergometry yielded similar levels of maximum ventilation (arm 47.2, leg 48.6 l/min), maximum heart rates (126 v 124 beats/min), maximum tidal volume (1.5 v 1.6 l), and respiratory rate (30 v 29 breaths/min); but maximum oxygen consumption (1120 v 966 ml/min), maximum power output (62 v 26 w), and oxygen pulse (9.1 v 7.8 ml/beat) were all higher with leg than with arm ergometry. In addition, ventilation and heart rate at a given level of oxygen consumption were higher for arm than for leg work during both submaximal and maximal exercise. It is concluded that arm ergometry offers an alternative testing method to leg testing in patients with moderate chronic obstructive lung disease.

Arm↗
PubMed1988

Renal artery stenosis: the use of duplex ultrasound as a screening technique.

Over an 18-month period, 44 patients with hypertension were referred for evaluation of the renal arteries by duplex Doppler ultrasound. Those patients referred were pre-selected in that they were either young, or suffering from accelerated hypertension. Eleven patients (12 arteries) were considered to have characteristics suggesting renal artery stenosis. Of the 11 patients, nine have submitted themselves for further evaluation by angiography and radionuclide renography. These further investigations have identified seven true positive and three false positive results. Criteria for duplex diagnosis of renal artery stenosis are presented and a possible role for duplex Doppler ultrasound as a screening tool for renal vascular hypertension is discussed.

Adolescent↗
PubMed1988

Transvaginal ultrasound directed oocyte collection for in vitro fertilization: successes and complications.

From December 1985 to April 1986, 458 patients underwent 600 transvaginal ultrasound-directed oocyte pickups (TVOPU) in preparation for in vitro fertilization and embryo transfer at The Royal North Shore Hospital of Sydney. Collections (552) were performed under light general anesthetic and, more recently, 48 were performed with light sedation. At least one oocyte was collected in 98.7% of all TVOPUs. A total of 3117 follicles (greater than 12 mm) were aspirated and 2576 oocytes were collected. Ninety-two clinical pregnancies were established after embryo transfer in 474 cycles. Major operative morbidity was low, with three pelvic abscesses and three pelvic hematomas reported. The procedure was well accepted by patients, with only one expressing a preference for the laparoscopic method. TVOPU is now the preferred method of oocyte pickup in our unit.

Embryo Transfer↗
PubMed1988

Rett syndrome: clinical profile and EEG abnormalities.

We studied 7 children with Rett Syndrome, characterized by behavioral and motor abnormalities which superficially resemble infantile autism, and reviewed the records of 4 adults with the same symptoms. Clinical details are discussed. No abnormalities were found in analyses of amino acids and biogenic amine metabolites. EEG showed a clear pattern of chronological deterioration, with the pattern of marked waking/sleep background contrast appearing consistently only after 5 years of age. There was also a high incidence of spike discharges in the central (Rolandic) region. The clinical pattern of Rett Syndrome should be differentiated from the syndrome of autism.

Adolescent↗
PubMed1987

Properties of N-acetylglucosamine 1-phosphotransferase from human lymphoblasts.

Human lymphoblast and fibroblast cell lines from a patient with I-cell disease and normal individuals were characterized with respect to certain properties of UDP-N-acetylglucosamine:lysosomal enzyme precursor N-acetylglucosamine phosphotransferase. The enzyme isolated from normal lymphoblast and fibroblast cell lines expressed similar kinetic properties, substrate specificities and subcellular localizations. Coincident with the severe reduction of N-acetylglucosamine phosphotransferase activity in both I-cell fibroblast and lymphoblast cell lines, there was an increased secretion of several lysosomal enzymes compared to normal controls. Subsequent examination of N-acetyl-beta-D-hexosaminidase secreted by the I-cell lymphoblasts demonstrated a significant increase in adsorption of the I-cell enzyme to Ricinus communis agglutinin, a galactose-specific lectin. However, the I-cell lymphoblasts did not exhibit the significant decrease in intracellular lysosomal activities seen in I-cell fibroblasts. Our results suggest that lymphoblasts not only represent an excellent source for the purification of N-acetylglucosamine phosphotransferase, but in addition, represent a unique system for studying alternate mechanisms involved in the targeting of lysosomal enzymes.

Cell Line↗