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Biomedical subjects

D Roberts

Publications and source records attributed to D Roberts.

At least 289 records · Page 16Linked to original sources
PubMed1990

The effects of methoxamine and epinephrine on survival and regional distribution of cardiac output in dogs with prolonged ventricular fibrillation.

This study compares the effects of methoxamine, a pure alpha 1-agonist, and epinephrine on cerebral and myocardial blood flow, central hemodynamics, and survival in a randomized placebo-controlled fashion during prolonged ventricular fibrillation (VF) in a canine model. Twenty-four anesthetized and ventilated adult mongrel dogs were instrumented for regional blood flow determinations using radio-labeled microspheres. The dogs were randomized to receive either 20 mg of methoxamine as a single intravenous bolus or repeated boluses of 0.02 mg/kg of epinephrine, 0.2 mg/kg of epinephrine, or normal saline solution placebo beginning at three minutes following induction of VF and initiation of closed chest cardiac massage (CCCM). Organ blood flow measurements were determined during normal sinus rhythm and after five and 20 minutes of VF. All six dogs receiving methoxamine were successfully resuscitated in contrast to only one in each of the epinephrine-treated groups and none of the dogs receiving placebo (p less than .01). Although epinephrine was associated with significantly higher blood pressures than placebo during cardiopulmonary resuscitation (CPR), blood pressures achieved with methoxamine were significantly higher than those observed in the other three treatment groups (p less than .001). Cerebral blood flow was significantly higher with both methoxamine and high-dose epinephrine (p less than .05). Mean left and right ventricular myocardial flows were highest with methoxamine but this did not achieve statistical significance. In contrast, organ flows measured in the animals receiving the lowest dose of epinephrine were not significantly higher than those associated with placebo. Cardiac output after 20 minutes of CPR was significantly lower with high-dose epinephrine than with methoxamine or placebo (p less than .05). Our results suggest that methoxamine significantly improves regional cerebral blood flow and survival during CPR and although high-dose epinephrine is associated with comparable improvements in regional cerebral blood flow, this treatment is associated with deterioration in central hemodynamics during prolonged VF and does not enhance survival.

Animals↗
PubMed1990

Blood cell filtrability: reference values and clinical applications.

In 500 healthy individuals cell deformability, expressed as cell filtration rate in microliters/s was studied with a microcirculation method in order to determine reference values for this method for various age groups in adults. The overall normal red cell filtration rate (RFR) value in healthy individuals was 69 +/- 11 microliters/s. When one compared the age groups 20-29 and 60-69 years, the reductions for RFR, white cell filtration rate (WFR), plasma-white cell filtration rate (P-WFR) and whole-blood filtration RATE (WBFR) was 26 +/- 3 (p less than 0.01), 32% +/- 5 (p less than 0.01), 28% +/- 4 (p less than 0.01) and 28% +/- (p less than 0.01) respectively. The reduction of RFR was graded into four clinical classes (GCTA = Gothenburg Cardio-Thoracic Association); I = 1-24%, II = 25-49%, III = 50-74%, IV = 75-100%, class I with lowest and class IV with highest reductions. Significant reductions in the mean RFR were noted in patients undergoing heart surgery (36% +/- 3, P less than 0.01, class II), patients with cardiac arrest (55% +/- 5, p less than 0.01, class III), occlusive arterial disease (58% +/- 6, p less than 0.001, class III) diabetes (45% +/- 5, p less than 0.01, class II). None of the patients had a normal RFR value. This study demonstrated a loss of cell deformability with age and disease.

Adult↗
PubMed1990

A method for reconstruction of large full-thickness defects of the bony thorax.

Wide resection in 12 cases of malignant or potentially malignant lesions of the chest wall resulted in full-thickness loss of skeleton and frequently of overlying soft tissues (defect greater than or equal to 15 cm in its smallest diameter or at least 90% of the sternum resected). In reconstruction of the defect, steel bars were used to replace lost ribs and a double layer of Marlex mesh for intercostal spaces. Soft-tissue coverage and primary closure were accomplished with current plastic surgical procedures and good stability of the chest wall was achieved. Protracted respiratory support was required in only one case. Postoperative pain was managed with epidural anesthesia and routine analgesics. Functionally and cosmetically satisfactory long-term results were obtained, with no infection and no need for removal of prosthetic material. The overall 5-year and 10-year actuarial survival rates were 60% and 37.5%. If lesions are radically resectable, the extent of thoracic wall resection need not be restricted because of inability to close the defects.

Adult↗
PubMed1990

Host immunoglobulin on spleen-derived Leishmania donovani amastigotes.

Leishmania donovani, an intracellular pathogen in vertebrates, is found as an amastigote within cells of reticuloendothelial origin. The spleens of experimentally infected Syrian hamsters are frequently used as a source of amastigotes for studies of host-parasite interactions, but amastigotes isolated from hamster spleens have been found to have surface-bound host immunoglobulins, which may confound interpretation of such studies.

Animals↗
PubMed1990

A clinic for the prevention of osteoporosis in general practice.

A clinic for women aged 40-60 years, offering screening and education about diet and hormone use and other measures for the prevention of osteoporosis, was organized in a group practice. Out of 582 eligible women contacted from the age-sex register, 252 (43%) attended the clinic. A year after the start of the clinic postal questionnaires were sent to all attenders and non-attenders to ascertain smoking habit, hormone use, calcium intake and social class. The use of hormone replacement therapy by the clinic attenders increased from a baseline of 15% to 45% but this had decreased to 38% one year later. Attending women were of higher social class and had slightly higher calcium intake than non-attenders. Although the use of hormone replacement therapy for prevention of osteoporosis is controversial, the risks and benefits were explained carefully to the women and the clinic provided a valuable opportunity for screening for weight problems, high blood pressure, menstrual problems and for health education about diet for the woman and her family.

Adult↗
PubMed1990

Comparison of peritonitis rates during long-term use of standard spike versus Ultraset in continuous ambulatory peritoneal dialysis (CAPD).

Continuous ambulatory peritoneal dialysis (CAPD) is an increasingly popular means of end-stage renal disease replacement therapy. Unfortunately, peritonitis continues to be a major source of both morbidity and mortality. The Ultraset incorporates a "flush-before-fill" concept which should theoretically decrease peritonitis rates when compared to the standard spike procedure, while allowing patients the convenience of disconnect. To investigate the impact of long-term use of the Ultraset on peritonitis rates, we conducted the following study. We prospectively compared 21 new CAPD patients using the standard spike to 20 new CAPD patients using the Ultraset. Peritonitis episodes, episodes of exit-site infection, and the association of peritonitis with exit-site infection were monitored. Peritonitis rates were 7.57 months/episode for the group using the standard spike vs. 27.79 months/episode in the group using the Ultraset. Exit-site infection rates were 22.21 months/infection with the standard spike vs. 37.05 months/infection with the Ultraset. Using Kaplan-Meier plots, there was a statistically significant difference in the estimated time to the first episode of peritonitis, but there was no statistically significant difference regarding the risk of exit-site infections.

Adult↗
PubMed1990

Thermal trauma.

A review of the anatomy and physiology of the skin and how it relates to the pathophysiology of thermal trauma is summarized in this article. Using nursing diagnosis, the authors home in on the unique problems and concerns that befall the thermally injured patient.

Adolescent↗
PubMed1990

Serum ferritin values in elite speed and synchronized swimmers and speed skaters.

Reports of subnormal serum ferritin values for elite athletes are widespread. Human studies evaluating performance in the ferritin-depleted state have led to a questioning of the significance of low ferritin levels for athletic performance. However, the accelerated iron metabolism and subnormal iron intake-uptake demonstrated by some athletes suggests that a point occurs in training at which the body must draw on its reserves. In consideration of this problem, serum ferritin, hemoglobin, hematocrit, serum Fe, and total iron-binding capacity levels were measured in elite Canadian female synchronized swimmers (n = 9), male speed swimmers (n = 7), and male and female speed skaters (n = 6, n = 6) over the course of two seasons of training and competition. Training sessions were monitored to document the workload carried out by each athlete. The midseason serum ferritin team values for the first and second years (mean +/- SEM) were as follows: synchro 48 +/- 10 micrograms.1 L, 24 +/- 6 micrograms.1 L; female speed skaters 57 +/- 14 micrograms.1 L, 51 +/- 7 micrograms.1 L; male speed skaters 94 +/- 27 micrograms.1 L, 72 +/- 19 micrograms.1 L; and male swimmers 66 +/- 13 micrograms.1 L, 56 +/- 7 micrograms.1 L. A significant decrease was seen in both serum ferritin and hemoglobin for the synchronized swimmers and in serum ferritin for the male speed skaters (p less than 0.05). These results suggest that a tendency exists for a decrease in serum ferritin levels from season to season.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Heart rate and blood lactate concentration during on-ice training in speed skating.

Heart rates and blood lactate concentrations were measured in four sprint and three all-round male members of the Canadian National Speed Skating Team. Responses to various training programs were obtained over a two-week period in November following four weeks of ice training, and in January during mid-season competition. Seven different training programs used by sprint and all-round speed skaters were monitored including a skating velocity and heart rate/lactate response. The protocol for this response was 5 x 4 min exercise intervals with 4 min recovery. A significant increase in blood lactate (3.9 +/- 0.4 to 5.2 +/- 0.5 mmol.L-1) was observed between intensity levels 2 and 3. During the specific 1500 m training program for sprinters, there was an increase in blood lactate and a decrease in heart rate for each exercise interval, despite a maintenance in lap speed throughout the whole program. The highest blood lactate concentrations seen in training and competition were 18.5 +/- 0.3 mmol.L-1 in specific 1500 m training and 17.7 +/- 1.8 mmol.L-1 following the 1000 m race.

Adult↗
PubMed1989

Association of sorcin with drug resistance in L1210 cells.

L1210 sublines independently selected for resistance to teniposide (VM-26), etoposide (VP-16), doxorubicin (DOX), dactinomycin (DACT), or vincristine (VCR) express an anionic, 22-kDa protein that is not observed in extracts of parental L1210 cells. Antibody raised against sorcin, an acidic calcium-binding protein overproduced in many other cells resistant to these agents, cross-reacts with the 22-kDa polypeptide. The levels of the 22-kDa protein (sorcin) increase with the relative levels of drug resistance of the L1210 sublines. The appearance of sorcin in these various sublines further supports the notion that the overproduction of this protein is related to the general phenomenon of multidrug resistance rather than to specific drug resistance and that selection for resistance to teniposide produces L1210 sublines with multidrug resistance.

Animals↗
PubMed1989

Eleven years' experience with Carpentier-Edwards biological valves in relation to survival and complications.

The Carpentier-Edwards porcine valve bioprosthesis was implanted in 299 patients (325 prostheses) from April 1976 to April 1982. The series consisted of aortic valve replacement in 150 patients, mitral valve replacement in 120, multiple valve replacement in 26, pulmonary valve replacement in 2 and tricuspid valve replacement in 1 patient. The postoperative follow-up was 100% complete. The total accumulated follow-up was 1956 patient-years. The early mortality was 6.4% (20 patients) and the late mortality was 22% (62 patients). Valve-related mortality was seen in 8 patients (2.7%): 1 paravalvular leak during the 1st 30 postoperative days and 7 late mortalities (1 endocarditis, 2 paravalvular leaks and 4 deaths during reoperation). Three operative deaths (1.5%) occurred. The overall patient survival including operative deaths was 78.5% +/- 5% at 5 years and 66% +/- 4% at 10 years. The incidence of the different complications were: thromboembolism in 5 patients (1.7%) with a risk of 0.3%, haemorrhage in 1 (0.3%) with a risk of 0.05%, endocarditis in 2 (0.7%) with a risk of 0.1%, and paravalvular leak in 11 patients (3.7%) with a risk of 0.6%. There was a high incidence of tissue failure during the last 6 years which occurred in 54 patients (18%) with a risk of 2.7%. Sixty-seven patients (22.5%) were reoperated upon during the 11 years with an annual risk of 3.4% and the main cause of reoperation was primary tissue failure. The Carpentier-Edwards biological valve was shown to be efficient during the first 5 years of implantation after which the incidence of tissue failure increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

A national outbreak of Salmonella typhimurium DT 124 caused by contaminated salami sticks.

An outbreak of Salmonella typhimurium DT 124 infection which affected 101 people in England in December 1987 and January 1988 was detected through surveillance of laboratory reports from medical microbiology laboratories of the NHS and PHLS. Within 1 week of noting the increase in reports, epidemiological and microbiological investigations identified a small German salami stick as the vehicle of infection and the product was withdrawn from sale. The epidemiological investigation highlighted the occurrence of a long incubation period, bloody diarrhoea. Prompt recognition and investigation of the outbreak prevented further cases of severe infection.

Adolescent↗
PubMed1989

Pharmacokinetics of teicoplanin in subjects with varying degrees of renal function.

The pharmacokinetics of teicoplanin were studied in 20 subjects with varying degrees of renal function after administration of a single 200 mg intravenous dose. Pharmacokinetic parameters were calculated with a three compartment open model and by non-compartmental analysis. The elimination half-life increased as creatinine clearance decreased (rs = -0.87, P less than 0.001). The distribution volume was 1.0 (+/- 0.3) 1/kg of actual body weight and did not vary with changes in creatinine clearance. In normal subjects the main route of elimination was renal. The plasma clearance of teicoplanin correlated with creatinine clearance (rs = 0.91, P less than 0.001). At lower levels of creatinine clearance the variation in elimination half-life was such that we recommend individualization of the teicoplanin dosage following the measurement of the drug concentration in plasma.

Adult↗
PubMed1989

Biochemical aspects of peripheral muscle fatigue. A review.

Muscular fatigue is of critical importance to performance and as such has been the subject of numerous investigations. However, a clear cause remains elusive. Although many factors have been identified, this review deals only with those which occur distal to the neuromuscular junction. Factors discussed include: energy supply (ATP/creatine phosphate, glycogen, oxygen, and free fatty acids); the accumulation of metabolites (lactate/hydrogen ions, calcium, ammonium, electrolyte and water shifts); and, the special case of eccentric work. The results of many studies using various methodologies are examined. Peripheral fatigue appears to be a complex series of interactions with variable influence on the development of fatigue depending upon the nature of the work performed.

Energy Metabolism↗