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Biomedical subjects

E R Smith

Publications and source records attributed to E R Smith.

At least 145 records · Page 8Linked to original sources
PubMed1991

Experimental instrumentation and left ventricular pressure-strain relationship.

Pericardial pressure measurement with a balloon transducer requires opening and reapproximating the pericardium. If this instrumentation significantly compromises pericardial volume, the heart may be constrained, exaggerating the magnitude of pericardial pressure and thus altering the left ventricular end-diastolic pressure-volume relationship. In open-chest dogs, we studied the effects of opening the pericardium, inserting a pericardial balloon transducer and myocardial sonomicrometer crystals, and reapproximating the pericardium on the left ventricular end-diastolic pressure-strain relationship (LVEDPSR). After a thoracotomy, sonomicrometer crystals were inserted through small holes (less than 3 mm) in the pericardium to measure LV segment length. A micromanometer with a reference lumen was used to measure LV pressure. LVEDPSRs were recorded in the following situations: 1) before the pericardium was opened (but after the crystals were inserted); 2) after the pericardium was opened, the heart was instrumented (4 pairs of crystals and 1 balloon), and the pericardium was reapproximated with interrupted sutures; and 3) after the pericardium was removed. For each dog, a cubic regression equation was fitted to the data obtained before opening the pericardium, and the 95% confidence intervals for the individual data points were determined. In each case, the LVEDPSR obtained after instrumentation was similar to the LVEDPSR described before opening the pericardium. Furthermore, data obtained after instrumentation were uniformly located within the confidence intervals of the LVEDPSR obtained before opening the pericardium and instrumenting the heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Investigation of reports of sexual dysfunction among male chemical workers manufacturing stilbene derivatives.

A Health Hazard Evaluation was conducted by the National Institute for Occupational Safety and Health in an area of a large chemical plant that manufactured the stilbene derivative 4,4'-diaminostilbene-2,2'-disulfonic acid, an intermediate used for the production of optical brightening agents. Men employed in the area reported problems with impotence. The study population consisted of 44 men aged 20-57 years (mean age 37) employed in the area at the time of the evaluation. An industrial hygiene investigation, health and work history questionnaire survey, physical examinations, and blood chemistry and serum hormone evaluation were conducted. Fourteen percent of the men reported symptoms of impotence over the preceding 6 or more months, 7% had potency problems of shorter duration, and 7% were not currently impotent but had experienced impotence for 6 or more months in the past; 36% experienced decreased libido, all since beginning work in the production area. Low levels of serum testosterone (less than 350 ng/dl) were observed in 37% of the men. The low serum testosterone concentrations were not accounted for fully by diurnal variation or an effect of rotating shift work. It is suggested that exposures to chemicals possessing estrogenic activity may be related to the observed health effects in these workers.

Adult↗
PubMed1990

Drug utilization review in a teaching hospital: experience with vancomycin.

A prospective, two-phase, drug utilization review (DUR) was performed at the Royal Adelaide Hospital (RAH) to determine the extent and pattern of vancomycin use. For all patients commencing oral or parenteral vancomycin, treatment indication, route of administration, duration of therapy, results of culture and sensitivity tests, adverse drug reactions and results of therapeutic drug level monitoring were recorded. Vancomycin courses were classified as being for therapy or prophylaxis and compared with predetermined audit criteria to assess appropriateness of use. During the 8 week initial phase, data on 62 treatment courses in 59 patients were recorded, 50% for therapy and 50% for prophylaxis. Sixty four percent were classified as inappropriate, occurring in 32% of therapeutic courses and 97% of those for prophylaxis. During the 10 week re-evaluation, conducted 10 months later, data for 43 treatment courses in 43 patients were reviewed, 42% for therapy and 58% for prophylaxis. Sixty five percent were inappropriate occurring in 17% of therapeutic courses and 100% of the prophylactic courses. When compared with the initial phase, the re-evaluation demonstrated a decrease in the empirical use of vancomycin in the combination treatment of neutropaenic fever and also in the duration of vancomycin use for surgical prophylaxis. During both study phases, criteria contraventions were mostly due to inappropriate indication or duration of therapy. The cost of inappropriate vancomycin use was reduced by over 50% between survey phases, from $Aus11,500 or 55% of total vancomycin cost during the initial phase to $Aus3,600 or 25.7% during the re-evaluation. The most effective of the remedial strategies implemented after the initial phase was direct consultation with prescriber groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Vitamin E levels in premenstrual syndrome.

To determine whether changes in peripheral vitamin E levels are associated with symptoms of premenstrual syndrome, 10 patients with premenstrual syndrome and 10 control subjects were studied. They gave blood at 2- or 3-day intervals throughout three menstrual cycles. The vitamin E was measured by fluorometry after hexane extraction and luteinizing hormone was measured by radioimmunoassay. In the control group, vitamin E values were 854 +/- 45 micrograms/dl (mean +/- SE) during the luteal phase and 925 +/- 55 micrograms/dl during the follicular phase. No significant changes were noted between the two values. In the patients with premenstrual syndrome, the values were 849 +/- 53 micrograms/dl during the luteal phase, which was not significantly different from 858 +/- 48 micrograms/dl during the follicular phase. No significant changes were noted between the control group and the patients with premenstrual syndrome in either the luteal or the follicular phase. Vitamin E deficiency in patients with premenstrual syndrome was not shown by peripheral vitamin E levels in our study.

Adult↗
PubMed1990

Yohimbine attenuates aging-induced sexual deficiencies in male rats.

Since yohimbine strongly stimulates sexual motivation/arousal in rats, it was of interest to determine whether the arousal deficit in aging male rats could be reversed by yohimbine. Three groups from each of two ages (approximately 3 and 15 months) received vehicle, 1 or 4 mg/kg yohimbine. In the mounting test (for arousal/motivation), 1 mg/kg yohimbine significantly increased mount frequency in middle-aged rats, though not to the level of the young animals. In the mating test, the percentage of aging rats intromitting and displaying ejaculatory behavior was less than in the young group, but after 1 mg/kg yohimbine, these behaviors were significantly increased. Vehicle-treated middle-aged rats which had mated showed significantly elevated intercopulatory intervals and ejaculatory behavior latencies. These measures were reduced by 1 mg/kg yohimbine. While behavioral facilitation following yohimbine in aging rats did not reach that of young yohimbine-treated rats, they reached levels at or close to those of nontreated young animals. We conclude that yohimbine treatment can improve age-related deficits seen to occur in aging male rat sexual behavior.

Aging↗
PubMed1990

Effects of intrathecal administration of 8-OH-DPAT on genital reflexes and mating behavior in male rats.

Systemic administration of the 5HT1A receptor agonist, 8-OH-DPAT, consistently decreases the threshold of ejaculatory behavior and enhances some aspects of arousal. Previous findings by others demonstrated the in copula ejaculatory behavior effect using intrathecal (IT) injection at the level of the lumbosacral spinal cord, but the dose used was in the range that produced results systemically. This study aimed at a) a more comprehensive study of the sexual effects of 8-OH-DPAT and b) use of IT doses of 8-OH-DPAT below those effective when administered systemically. The ex copula genital reflex test showed severe inhibition. At doses of 5 micrograms or more, significant inhibition of the percentage of rats displaying ejaculation occurred, and the two highest doses also significantly reduced the percentage of rats displaying erection. In the in copula mating test, 20 and 80 micrograms IT 8-OH-DPAT, significantly reduced ejaculation latency, intromission frequency and intercopulatory interval. Copulatory plugs, collected at the highest dose only, showed a trend towards weight reduction. We conclude that the facilitation of ejaculatory behavior and some measure of arousal by 8-OH-DPAT can be mediated directly via the lumbosacral spinal cord. An hypothesis for explaining the inhibitory effect on ejaculation ex copula is presented, but the inhibitory effect on erectile reflexes is without interpretation.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1990

Effects of four beta-adrenergic receptor antagonists on male rat sexual behavior.

Antihypertensive medication has been reported to cause serious sexual side effects in men. Frequently mentioned as causing sexual dysfunction are beta-adrenergic receptor antagonists. The purpose of this study was to examine in detail the effects of beta blockers on adult male rat sexual behavior. Thirty minutes following a single subcutaneous injection of propranolol, pindolol, atenolol or labetalol, mating tests were conducted. The mixed beta 1- and beta 2-adrenergic antagonists, propranolol and pindolol, profoundly inhibited male sexual behavior. At the 5 and 10 mg/kg doses, propranolol inhibited ejaculatory behavior to the extent that only 9.1 and 8.3% respectively showed the behavior while pindolol reduced this behavior to 36.4% (16 mg/kg). These drugs also adversely affected various parameters of behavior in a dose-dependent manner. The selective beta 1 antagonist, atenolol, had only minor effects and labetalol even less so at the doses tested. It was suggested that the strongly inhibitory effects of propranolol and pindolol on male rat sex behavior may well be due to their 5-HT1A antagonistic binding properties rather than their beta-antagonistic properties.

Adrenergic beta-Antagonists↗
PubMed1990

Effects of intrathecal and systemic administration of buspirone on genital reflexes and mating behavior in male rats.

Buspirone was studied to determine whether the detailed profile of male sexual behavior observed following treatment with the prototypical 5-HT1A ligand, 8-OH-DPAT, can be generalized to other 5-HT1A agonist drugs. Systemic and intrathecal (IT) routes of administration were compared. Like DPAT, significant reduction in intromission frequency followed IT infusion of buspirone (80-160 micrograms) as did intraperitoneal (IP) injection (1-4 mg/kg). IT doses of 80-160 micrograms and all IP doses significantly reduced ejaculation latency. Intercopulatory interval significantly decreased following IP buspirone but not after IT infusion although there were trends in that direction. All IP doses and 80 micrograms IT significantly shortened the postejaculatory interval. Buspirone inhibited erection and/or ejaculation in the ex copula reflex test. A decrease in percentage of rats displaying erections and ejaculation occurred following either route of administration. Ejaculation was significantly inhibited at the low IT dose of 40 micrograms. We conclude that buspirone affects sexual behavior very much like DPAT or other 5-HT1A drugs, to the extent known. Sexual effects of buspirone were generally similar regardless of route of administration, but the effective doses were clearly lower with IT treatment.

Animals↗
PubMed1990

Clonidine suppresses copulatory behavior and erectile reflexes in male rats: lack of effect of naloxone pretreatment.

Adrenergic transmitters and opioid peptides are implicated in the regulation of male sexual behavior. In the present studies we examine a possible interaction between these two neurochemical systems in the regulation of components of male sexual behavior. In mating tests, clonidine (0.25 mg/kg, 6 min pretest) induced a profound deficit in intromissive and ejaculatory behavior whereas naloxone (5 mg/kg, 20 min pretest) evinced a facilitation of ejaculatory behavior, evidenced by decreases in the ejaculation latency in the initial copulatory series and by decreases in ejaculation latency and intercopulatory interval in the second copulatory series. Importantly, prior treatment with naloxone did not prevent or attenuate the copulatory suppression induced by clonidine. In ex copula penile reflex tests, clonidine (0.25 mg/kg, 6 min pretest) decreased the incidence of seminal emission and the number of penile responses (erections, cups and flips). Naloxone (5 mg/kg, 20 min pretest) was without effect on any of the parameters of penile reflex activity and, further, failed to prevent or attenuate the erectile suppression induced by clonidine. A final study evaluated the dose-response relationship of clonidine-induced erectile dysfunction. A similar degree of erectile dysfunction was observed after 0.005, 0.025 or 0.25 mg/kg clonidine, whereas 0.0005 mg/kg was without effect. Previous studies demonstrated a dose-dependent inhibition of mounting, intromissive and ejaculatory behavior, with 0.25 mg/kg selectively eliminating ejaculatory behavior in mating tests. These data demonstrate a dose-dependent inhibition of penile reflexes, with inhibition occurring at doses lower than those required to induce copulatory dysfunction. Further, we suggest that opioid receptors sensitive to naloxone blockade are not involved in the clonidine-induced suppression of copulatory or erectile function.

Animals↗
PubMed1990

The dependence of the time constant of left ventricular isovolumic relaxation (tau) on pericardial pressure.

The purpose of this study was to investigate the dependence of tau, the time constant of left ventricular (LV) isovolumic relaxation, on pericardial pressure and to compare values of tau as determined by the methods of previous investigators and by a standard exponential curve fit. All of the more recent methods involve an additional parameter--the pressure to which the exponential relaxation finally declines (PB, the pressure intercept in the method of Craig and Murgo and the asymptote in the exponential fits). An additional purpose of the study was to determine the relation of these parameters to pericardial pressure. In eight closed-chest anesthetized dogs, tau was calculated from intracavitary (Plv) and transmural LV pressure (Plv = Plv-Pper) by each method as pericardial (Pper) and LV end-diastolic pressure were changed by pericardial infusion and intravenous volume loading. The time constant determined by the method of Weiss et al was dependent on pericardial pressure; the time constants determined by the other methods were not. PB and the asymptotes were found to be similar and to increase almost equally with pericardial pressure. When pericardial pressure was zero, these values were approximately -20 mm Hg. Thus, both these parameters seem to indicate the same baseline pressure, a pressure that increases pari passu with pericardial pressure. Reported changes in the value of tau calculated from intracavitary LV pressure by the method of Weiss et al may reflect factors other than changes in LV diastolic function.

Animals↗
PubMed1990

Vitamin A levels in premenstrual syndrome.

To determine whether changes in peripheral vitamin A levels are associated with symptoms of premenstrual syndrome (PMS), 10 PMS patients and 10 controls were studied. They gave blood at 2- or 3-day intervals through three menstrual cycles. The vitamin A was measured by fluorometry after cyclohexane extraction. In the controls, vitamin A values were 68.0 +/- 3.2 micrograms/dL (mean +/- SE) during the luteal phase and 69.8 +/- 4.2 micrograms/dL during the follicular phase. No significant changes were noted between the two values. In the patients, the values were 73.9 +/- 4.2 micrograms/dL during the luteal phase, which was not significantly different from 72.7 +/- 1.8 micrograms/dL during the follicular phase. No significant changes were noted between the controls and the patients in either the luteal or the follicular phase. Vitamin A deficiency in PMS patients was not demonstrated in our study.

Adult↗
PubMed1990

Assessment of the splanchnic vascular capacity and capacitance using quantitative equilibrium blood-pool scintigraphy.

A series of human and animal experiments were carried out to assess the usefulness of equilibrium blood pool scintigraphy (EBPS) to study acute changes of the splanchnic vascular capacity and the splanchnic vascular pressure-volume (P-V) relationship. Corrected regional abdominal count rate changes, before and after various pharmacologic interventions, were used to assess regional splanchnic vascular volume changes. Animals were instrumented to manipulate and record splanchnic venous pressures. In patients, splanchnic vascular capacity increased by 5.2 +/- 6.9% (p less than 0.001) after 0.6 mg sublingual nitroglycerin while no significant change was noted after sugar pills (0.9 +/- 5.2%, p greater than 0.3). In dogs, splanchnic vascular capacity decreased by a mean of 16% during infusion of angiotensin (p less than 0.001) and increased by a mean of 32% during infusion of nitroprusside (p less than 0.001). The splanchnic vascular P-V curve was shifted rightwards during nitroglycerin administration. Thus, using the radionuclide technique we detected the expected qualitative and quantitative shifts in splanchnic capacity and capacitance. We conclude that EBPS is a useful method to assess acute changes of 1) the splanchnic vascular P-V relationship, in invasive animal studies, and 2) the splanchnic vascular capacity in noninvasive human and animal studies.

Adult↗
PubMed1990

Cardiovascular medicine at the University of Calgary: a vignette of recent history.

On September 14 and 15, 1989, a symposium entitled 'Surgical and nonsurgical management of cardiovascular disease' jointly sponsored by the University of Calgary and Foothills Hospital was held to help mark the one year anniversary of an expansion of percutaneous transluminal coronary angioplasty and cardiac surgery services in Calgary to include an academically oriented program at the Foothills Hospital. This program complements and adds to the clinical program which has been active for many years at Calgary's Holy Cross Hospital. This occasion is an opportunity to review the remarkable progress and development over the past 20 years of cardiovascular medicine at the university and in the city of Calgary.

Alberta↗
PubMed1990

Ventricular diastole and the role of the pericardium.

In order to understand the mechanics of left ventricular (LV) diastolic filling it has become important to understand the role of the pericardium. This is because it has been demonstrated that the LV pressure-volume relationship can be shifted by previously unrecognized changes in pericardial "pressure" and, therefore, LV end-diastolic pressure (LVEDP) may be ambiguous as a measure of preload. The key to this understanding is to appreciate that (except in the case of pericardial effusion or tamponade) the pericardium impedes cardiac filling by exerting a stress, not by raising the pressure in the pericardial fluid, and that the magnitude of this stress is variable and relatively great. When animals or humans are volume loaded acutely, this stress is approximately equal to right ventricular (RV) filling pressure. Thus, while it may not be possible to estimate true preload from simple measurements of LVEDP, subtracting RV filling pressure from LVEDP may provide a useful estimate of transmural LVEDP. As an example of the effect of the pericardium, recent laboratory results indicated that the decrease in stroke volume which resulted from acute pulmonary embolization could be explained by reductions in LV preload. Transmural LVEDP and end-diastolic volume decreased in spite of the fact that LVEDP rose markedly. Since LVEDP increased while stroke volume decreased, it might have been concluded that contractility had decreased. However, this was shown not to be the case, since the reduction in stroke volume only corresponded to the reductions in transmural LVEDP and end-diastolic volume. Thus, appropriately accounting for pericardial constraint may allow many changes in LV systolic performance, hitherto thought to represent changes in contractility, to be explained on the basis of preload changes and the Frank-Starling mechanism.

Diastole↗