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Biomedical subjects

D Ferguson

Publications and source records attributed to D Ferguson.

At least 109 records · Page 6Linked to original sources
PubMed1987

Bovine bone morphogenetic protein (bBMP) fraction-induced repair of craniotomy defects in the rhesus monkey (Macaca speciosa).

Large cranial defects do not always heal spontaneously, especially in humans; often they have to be obturated with metallic or acrylic fillers. Bilateral cranial trephine defects, measuring 14-20 mm in diameter, were created in three Rhesus monkeys, providing a typical primate model system for investigations in comparative physiology of bone regeneration. Each skull had one control and one experimental trephine defect. Control defects were implanted with bovine serum albumin (BSA). Experimental defects were implanted with 100-200 mg of a partially purified fraction of bovine bone morphogenetic protein (bBMP) in two monkeys. In one monkey, the BMP was incorporated in a 1:1 poly(lactic) poly(glycollic) acid copolymer, high-viscosity formula. The animals were killed at eight weeks, ten weeks, and 16 weeks after implantation. The tissue responses were analyzed by computed histomorphometry and routine histologic examination. At each time interval, the BMP implanted defects produced more complete regeneration than the control implants. The morphogenetic response occurred in the following sequences: mesenchymal cell proliferation, chondrogenesis, and increased bone formation. BMP-induced osteogenesis may initiate the regenerative process. The copolymer releases BMP but may constitute a barrier to the end stages of replacement by new bone, and would be more useful in a low-viscosity rapidly biodegradable form.

Animals↗
PubMed1986

Contraception with the cervical cap: effectiveness, safety, continuity of use, and user satisfaction.

With the growing interest in barrier contraceptive methods, the cervical cap has come back into use in North America. We examined the cap's effectiveness, safety, continuity of use, and user satisfaction among 617 women who were fitted at a family planning clinic in Toronto, Canada, between May 1981 and November 1983. Follow-up information was available for 516 of these women. Using a life table analysis with Bayesian adjustment, the probability of becoming pregnant after 12 months of use was 0.166 with a standard error of 0.022. There is evidence that after 1 year of use the caps deteriorate and that this deterioration may increase the risk of pregnancy. Many of the women in this study were very satisfied with the cervical cap; however, such problems as dislodgement, discomfort to user and partner, difficulty with insertion and removal, and unpleasant odour affected acceptability and continuity of use. It is likely that these problems could be alleviated by improving the quality of or changing the materials, modifying the design to improve the fit, and providing a greater range of sizes.

Adolescent↗
PubMed1985

Prospective reimbursement for state-of-the-art medical practice: the case for invasive electrophysiologic evaluation.

This study is an examination of the economic consequences of invasive electrophysiologic (EP) evaluation for recurrent supraventricular tachycardia (SVT) and ventricular tachycardia (VT) on a tertiary health care facility during 1980 and 1981. The average cost of hospitalizations for EP evaluation was substantial (SVT, $6,990; VT, $13,897), as was the length of hospital stay (SVT, 12 +/- 8 days; VT, 24 +/- 8 days). The cost of a single EP procedure in the study period averaged $695 (range $200 to $1,206). During follow-up (1 to 3 years), there was substantial improvement in arrhythmia control on EP-based therapy in SVT and VT compared with prior empirical therapy. Cost:benefit analysis strongly favored EP-based therapy over empirical therapy (SVT, 6:1; VT, 18:1) in this follow-up period. Comparison with cost of noninvasive techniques for VT evaluation showed that EP evaluation had comparable cost. Current prospective reimbursement schedules have no DRG category for EP evaluation and do not fairly compensate hospitals for invasive or noninvasive arrhythmia studies. Invasive EP evaluation is both clinically effective and cost-effective in the management of patients with recurrent SVT and VT. Prospective reimbursement plans should include a specific DRG category for these studies.

Anti-Arrhythmia Agents↗
PubMed1985

Effects of a warm environment on energy balance in obese (ob/ob) mice.

Low rates of thermoregulatory heat production associated with low metabolic activity of brown adipose tissue, the primary site of thermoregulatory heat production, contribute substantially to the high efficiency of energy retention in obese (ob/ob) mice housed at 20 degrees C to 28 degrees C. To eliminate the need for thermoregulatory heat production lean and ob/ob mice were housed at 34.5 degrees C. At this temperature ob/ob mice still retained energy with a greater efficiency than lean littermates. Next, we investigated the possibility that the high efficiency of energy retention in ob/ob mice housed at 34.5 degrees C was related to depressed dietary-induced thermogenesis associated with low metabolic activity of brown adipose tissue. The sympathetic nervous system is a primary regulator of brown adipose tissue metabolism. Therefore, rates of norepinephrine (NE) turnover in brown adipose tissue, as an indicator of sympathetic nervous system stimulation of the tissue, were measured. Lean and ob/ob mice housed at 34.5 degrees C had equally low rates of NE turnover in their brown adipose tissue. Thus, the high efficiency of energy retention in ob/ob mice maintained at 34.5 degrees C is caused by factors other than low sympathetic stimulation of brown adipose tissue.

Adipose Tissue, Brown↗
PubMed1984

Reconstitution and partial purification of several Na+ cotransport systems from renal brush-border membranes. Properties of the L-glutamate transporter in proteoliposomes.

Brush-border membranes of renal proximal tubules were solubilized with deoxycholate and some proteins were separated and incorporated into proteoliposomes by a reconstitution procedure which was analyzed in detail. The proteoliposomes contained mainly polypeptides with molecular weights of 152,000, 94,000, and 52,000, each of which could be separated further into homologous polypeptides with different isoelectric points. In the proteoliposomes, Na+ cotransport systems for D-glucose, acidic and neutral amino acids, and mono- and dicarboxylic acids were demonstrated by showing that due to an inwardly directed Na+ gradient the substrate concentrations in the proteoliposomes increased significantly over their respective equilibrium values. Using inhibition experiments, selectivity of the different transporters could be demonstrated. Studying the reconstituted L-glutamate transporter in detail, countertransport of L-glutamate and K+ was shown (i) at Na+ equilibrium the intraliposomal L-glutamate concentration increased significantly over the equilibrium value if an outside-directed K+ gradient was applied; (ii) Rb+ influx was significantly stimulated by the outflux of L-glutamate. By applying a K+ diffusion potential across the liposomal membrane by addition of valinomycin it could be shown that during L-glutamate transport in the presence of Na+ and K+ positive charge is transferred together with L-glutamate and Na+. The apparent Km value of L-glutamate uptake driven by concentration differences of 89 mM Na+ (out greater than in) and 89 mM K+ (in greater than out) was 26.3 +/- 1.3 microM. The Vmax value of 70.2 +/- 2.3 pmol X mg of protein-1 X S-1 was half the value measured in intact membranes.

Amino Acid Transport System X-AG↗
PubMed1984

Health in the workplace.

General good health and the prevention of specific "non-occupational" disease, in addition to protection against occupational disease and injury, are already part of the aim and function of occupational health services. They are justified, if at all, mostly on the grounds of intangible benefits the virtue of which is not questioned. Concern over health costs and financial constraints are forcing industry to justify health expenditure. Yet, the health programmes can be justified, and industry has some obligation to adopt them.

Australia↗
PubMed1984

Management of recurrent ventricular tachycardia: economic impact of therapeutic alternatives.

The clinical and economic results of antiarrhythmic therapy selected on the basis of electrophysiologic (EP) studies in patients with recurrent ventricular tachycardia (VT) were examined and compared with previously administered empiric therapy. Twenty-nine patients with recurrent VT and organic heart disease, aged 39 to 78 years (mean 59 +/- 11) were evaluated. All patients had empiric therapy before EP studies and EP-based therapy after EP evaluation. Hospital records were analyzed from arrhythmia diagnosis 1 to 39 months (mean 7.5 +/- 10.4) before EP evaluation until completion of follow-up 1 to 20 months (mean 13.3 +/- 7.4) after EP studies. Clinical efficacy was assessed by comparing actual arrhythmic deaths or recurrences during EP-based therapy with predicted values on empiric therapy. Charges based on diagnosis-related groupings for empiric and EP-based therapy were compared. Charges for EP evaluation were included in the calculation for EP-based therapy. During empiric therapy, 1 to 7 unsuccessful drug trials (mean 3.7 +/- 1.6) were performed, with arrhythmia recurrences noted in all patients during a mean 7.5-month VT duration. Twenty-seven of 29 patients required 1 to 70 electrical terminations. There were 64 hospitalizations (mean 2.1 +/- 1.7) with a total length of hospital stay of 913 days (mean 31.0 +/- 19.9). EP evaluation required 90 EP procedures (mean 3.0 +/- 1.5) with a length of stay of 690 days (mean 23.8 +/- 12.0). During a follow-up period of 1 to 26.5 months (13.3 +/- 7.4) on EP-based therapy, 1 patient died suddenly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Multiply-resistant Staphylococcus aureus (bacteriophage type 90) in a special care baby unit.

An outbreak of infection in a special care baby unit due to a multiply-resistant Staphylococcus aureus is described. Although the organism was isolated from 35 babies over 1 year, only two were clinically infected, one of whom died of infection. New measures to prevent cross-infection were introduced but colonized babies continued to be detected. The unit was closed for several weeks but babies became colonized again after reopening. The route of cross-infection remained uncertain.

Cross Infection↗
PubMed1984

Advance prediction of transthoracic impedance in human defibrillation and cardioversion: importance of impedance in determining the success of low-energy shocks.

The purposes of this study were to evaluate a method that predicts transthoracic impedance in advance of defibrillating shocks in humans and to assess the importance of transthoracic impedance in low-energy defibrillation. Via defibrillator electrodes we applied 31 kHz current to the chest during the defibrillator charge cycle, before the defibrillating shock was actually delivered. The current flow was limited by transthoracic impedance; a microprocessor monitored the predischarge current flow and determined the predischarge impedance by calibration against known resistance values. Actual impedance to the defibrillating shock was also determined and compared with the predicted impedance. With this approach we predicted impedance in 19 patients who received 66 shocks for ventricular and atrial arrhythmias. Predicted impedance (y) correlated very well with actual impedance (x):y = .90x + 11.3; r = .97. To determine the importance of impedance in defibrillation and cardioversion, we prospectively gathered data from 96 patients who received shocks of various energies for ventricular or atrial arrhythmias. In patients with high transthoracic impedance (greater than 97 omega), low-energy shocks (less than or equal to 100 J) for ventricular defibrillation had only a 20% success rate as opposed to a 70% success rate for low-energy shocks in patients with low or average impedance (p less than .05). We conclude that transthoracic impedance can be accurately predicted in advance of defibrillation and cardioversion. This method permits the preshock identification of patients with high impedance in whom attempts to defibrillate with low-energy shocks are inappropriate.

Arrhythmias, Cardiac↗
PubMed1983

Regulation of protein intake in adult dogs.

To determine whether adult dogs are able to regulate their intake of protein, 2-year-old female Beagles were allowed self-selection from 2 diets that differed in concentration of protein. Such a feeding regimen permitted the dogs to select for protein without affecting energy intake. Within the 1st week of the 4-week study, the dogs had established their pattern of protein intake. They selected approximately 30% of metabolizable energy from protein. Adult female rats offered the same diets also selected 30% of metabolizable energy from protein. The results indicated that adult dogs are able to regulate protein and energy intake.

Animals↗
PubMed1982

Self-selected intake of carbohydrate, fat, and protein by obese (ob/ob) and lean mice.

Obese mice, self-selecting from three food cups containing carbohydrate, fat and protein supplemented with minerals and vitamins, selected the same proportion of energy from protein (approximately 20%) as did lean mice. Young obese mice also selected the same proportion of carbohydrate and fat as selected by lean mice, but adult obese mice self-selected a higher proportion of energy from fat and a lower proportion from carbohydrate than did lean mice. The high preference by adult obese mice for fat was confirmed in additional studies employing two food cups, one containing a high-carbohydrate diet and the other a high-fat diet. We speculate that the preference by adult obese mice for fat is related to their insulin resistance.

Animals↗
PubMed1981

Aged abuse.

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Aged↗