Search PubMed⌕ Search

Biomedical subjects

L Watkins

Publications and source records attributed to L Watkins.

At least 37 records · Page 2Linked to original sources
PubMed1994

Synergistic effects of fish oil diet and dimethylthiourea in acute adriamycin nephrosis.

The synergistic effects of combining fish oil (FO) diet, which reduces thromboxane A production, with the free radical scavenger, dimethylthiourea (DMTU), were evaluated in acute adriamycin nephrosis, because proteinuria in adriamycin nephrosis is mediated by increased renal thromboxane A and free radical production. The effects of combined evening primrose oil (EPO) and DMTU were compared with the DMTU + FO combination because EPO increases prostaglandin E but not thromboxane A. After 7, 14, and 21 days, proteinuria was significantly (p < 0.05) reduced in rats receiving either DMTU + corn oil (CO) or DMTU + FO compared with untreated control rats. However, after 21 days, rats receiving DMTU + FO had significantly reduced urine protein excretion compared with those receiving DMTU + CO (103.9 +/- 20 mg daily vs 351.8 +/- 29.8 mg daily; P < 0.05). In contrast to FO, rats receiving EPO + DMTU had similar urine protein excretion to rats receiving DMTU + CO after 21 days (170.2 +/- 20.34 mg daily vs 179.45 +/- 26.38 mg daily). The mean serum cholesterol concentration was significantly (P < 0.01) reduced in rats receiving DMTU + FO (195.2 +/- 23.8 mg/dL) compared with DMTU + CO (377.9 +/- 28.5 mg/dL). Serum triglyceride levels also were significantly (P < 0.01) reduced in rats receiving DMTU + FO (52.5 +/- 26.4 mg/dL) compared with DMTU + CO (100.5 +/- 36.9 mg/dL). No significant differences in serum cholesterol concentrations or triglycerides occurred between rats receiving DMTU + CO and DMTU + EPO. Renal glutathione content was significantly (P < 0.05) increased by 23% in normal rats receiving FO diet and by 34% in rats receiving combined DMTU + FO compared with CO alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

A technique for improved blood sampling during sleep studies.

Research protocols often require that blood samples be drawn during sleep. This study compares the efficacy of obtaining nocturnal blood samples using a standard heparinized intravenous setup versus the same intravenous setup used in conjunction with a small chemical heating pad. The chemical heating pad significantly improved the number of blood samples obtained and the maintenance of intravenous patency. The use of a chemical heating pad is an economical way to resolve the frustration of lost blood samples while maintaining a reasonable environment to monitor sleep.

Adult↗
PubMed1993

Valvular disease in the elderly: influence on surgical results.

Aortic valve disease in the elderly is primarily calcific stenosis with preservation of left ventricular function. In contrast, mitral valve disease in the elderly often is ischemic in nature with damage occurring to both valve and myocardium. The present study was undertaken to compare results of aortic (AVR) and mitral valve replacement (MVR) in the elderly and to ascertain predictors of poor outcome. Because patients who had concomitant coronary artery bypass grafting (CABG) are included (51% for AVR, 55% for MVR), patients who had isolated CABG were used as a comparison group. Between January 1, 1984, and June 30, 1991, 1,386 patients aged 70 years and older underwent CABG (n = 1,043), AVR (n = 245), or MVR (n = 98). The operative mortality rates were 5.3% for AVR, 20.4% for MVR, and 5.8% for CABG. Late follow-up of patients undergoing operation in 1984 and 1985 was available for 98% (231/237). Overall survival was comparable for all three groups through the first 5 years of follow-up (AVR, 68% +/- 8%; MVR, 73% +/- 8%; CABG, 78% +/- 3%). After 5 years, survival for patients having AVR and MVR was less than that for those having CABG. Patient age, sex, New York Heart Association functional class, concomitant CABG, prosthetic valve type, native valve pathology, and preoperative catheterization data were examined as possible predictors of outcome by multivariate logistic regression.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Centrifugal ventricular assist device for support of the failing heart after cardiac surgery.

OBJECTIVE: To determine the morbidity and mortality associated with use of centrifugal ventricular assist devices for postcardiotomy cardiogenic shock and to determine factors that might influence outcome and thus, aid in patient selection. DESIGN: A retrospective study. SETTING: Surgical intensive care unit in a university hospital. PATIENTS: During a 6-yr period, a total of 7,385 adult patients underwent cardiac operations requiring cardiopulmonary bypass. Myocardial protection consisted of single-dose cold crystalloid cardioplegia and continuous topical hypothermia by saline lavage. A total of 72 (1%) patients developed postcardiotomy cardiogenic shock. Of 72 patients, 28 met the institutional criteria and were placed on centrifugal ventricular assist devices. INTERVENTIONS: Twenty-eight adult patients with postcardiotomy cardiogenic shock were supported with centrifugal ventricular assist devices. MEASUREMENTS AND MAIN RESULTS: A total of 15 patients received left ventricular assist devices, five received right ventricular assist devices, and eight received both right and left ventricular assist devices. Mean age of ventricular assistance patients was 50.8 +/- 12.9 yrs (range 22 to 72), and mean duration of ventricular assistance was 2.8 +/- 2.5 days (range 4 hrs to 10 days; median 2 days). Twenty-five complications occurred in 16 patients and included bleeding (13), tamponade (2), systemic embolism (6), seizures (2), and sepsis (2). Nine patients required reexploration for bleeding or tamponade. Nine (32%) of 28 patients were discharged from the hospital. Ventricular assistance for cardiac failure after transplantation was associated with improved survival (p < .10), while age > 50 yrs and postoperative tamponade each showed trends toward association with mortality (p = .10). Survival was not predicted by gender, weight, time on cardiopulmonary bypass, aortic cross-clamp time, urgency of operation, or preoperative congestive heart failure. At 27 +/- 20 months follow-up, all survivors were alive and New York Heart Association functional class I or II. CONCLUSIONS: These results document a low incidence of ventricular assist device use in a surgical practice that employs a relatively simple method of myocardial protection. When postcardiotomy ventricular assistance was necessary, a centrifugal pump was used and successful outcome and satisfactory long-term results were possible in nearly one third of patients. Ventricular assistance for cardiac failure after transplantation was associated with improved survival. Older age is a relative contraindication to mechanical ventricular assistance.

Adult↗
PubMed1993

Hypotensive effect of clonidine is not mediated by enhanced baroreflex gain in rats.

We wished to examine whether enhanced depressor baroreflexes contribute to the hypotensive effect of clonidine in rats. Clonidine's hypotensive effect and clonidine's effect on baroreflex gain mean heart rate/mean blood pressure, (delta HR/delta BP) were compared under two conditions: in conscious rats with intact baroreflex control of HR, and in pentobarbital-anesthetized (PA) rats in which baroreflex control of HR is obtunded. Clonidine produced greater hypotension and bradycardia in PA rats than in conscious rats, but this greater hypotension was not associated with enhancement of baroreflex gain. Instead, clonidine-induced hypotension in PA rats was associated with a further decrease in baroreflex gain, whereas hypotension in conscious rats was not associated with any change in baroreflex gain. Selective pharmacologic blockade of sympathetic (i.e., with atenolol treatment) or parasympathetic (i.e., with methyl-atropine treatment) control of HR showed that clonidine decreased baroreflex gain in PA rats through inhibition of sympathetic control of HR. This study suggests that clonidine's hypotensive effect is not associated with enhancement of reflex bradycardic responses in rats.

Anesthesia↗
PubMed1993

Mechanisms underlying cardiovascular defense reaction evoked by dorsal periaqueductal gray stimulation.

Hemodynamic and autonomic mechanisms underlying the cardiovascular defense reaction elicited by electrical stimulation of the dorsolateral periaqueductal gray region were evaluated in pentobarbital sodium-anesthetized Sprague-Dawley rats. Stimulation of this area produced transient increases in mean arterial pressure and more sustained increases in heart rate, hindlimb blood flow, and plasma catecholamine levels. The pressor component of the defense reaction was due entirely to increased total peripheral vascular resistance; elevations in cardiac output occurred only at the end of the stimulation period when blood pressure had returned to resting values. The hindlimb vasodilatory response included distinct early and late components. The late component was produced by epinephrine-mediated activation of beta 2-receptors because it was abolished by bilateral adrenalectomy or treatment with butoxamine, a beta 2-receptor selective antagonist. In contrast, the early component was only partially reduced by adrenalectomy or butoxamine treatment. During conditions of constant flow provided by a pump-perfused hindlimb preparation, the early hindlimb vasodilatory response was eliminated and a neurogenic vasoconstrictor response revealed. This finding suggests that the early hindlimb blood flow response may result from shunting of blood from highly vasoconstricted vascular beds to relatively less constricted hindlimb vasculature.

Adrenalectomy↗
PubMed1993

Skull base chordomas: a review of 38 patients, 1958-88.

The presentation and results of treatment are reviewed for 38 patients with skull base chordoma treated at the National Hospital for Neurology and Neurosurgery between 1958 and 1988. With few exceptions, previous studies have combined results for clival and sacral chordomas, or for chordomas and other similar tumours such as chondrosarcoma, and thus it is difficult to be specific about effects of therapy. This study included histological review using immunohistochemistry to confirm diagnosis. Analysis of the survival data for our patients suggests that there are two subgroups with distinct survival patterns: one group with high mortality within the first 5 years, and a second group with an indolent disease process and near normal life expectancy. The age of the patients at presentation ranged from 7 to 78 years, with a mean of 44.3 years. Male: female distribution was 6:5. The commonest presentation was with cranial nerve palsy (94%) or with headache (60%). The most frequently involved cranial nerve was the VIth (60%), followed by the IXth and Xth (40% each). Comparing our results with those of 50 years ago, there was little improvement in the outlook for these patients, despite improvements in surgical approaches and the use of radiotherapy. The promising results in skull base tumours using proton therapy must be treated with caution until definite criteria for diagnosis and outcome have been established. There is a case for a multicentre prospective study of this disease.

Adolescent↗
PubMed1992

Automatic implantable cardioverter defibrillator: surgical approaches for implantation.

Surgical approaches for implantation of the automatic cardioverter defibrillator are sternotomy, left thoracotomy, subxiphoid, and subcostal. Although any one of these may be combined with insertion of one or more of the electrodes transvenously, surgical entry into the chest is required for every noninvestigational defibrillator implantation operation. The approaches differ in exposure provided for selecting electrode sites and for handling untoward events, in amount and location of tissue that must be divided or dissected, and in average time required. The operation is an electrical one. Its purpose is to obtain reliable rhythm sensing so that defibrillation or cardioversion shocks will occur only when necessary, and to obtain low enough defibrillation thresholds for shocks of 30 joules or less to have a 10-joule defibrillation safety margin. Many of the patients have had previous cardiac operations. They usually have low or very low ejection fractions. Intraoperative electrophysiological testing with often multiple defibrillation episodes is required. The choice of approach varies with the state of the patient, the institutional experience, and the surgeon. This article describes technique, and the advantages and disadvantages of the four approaches as used by four surgeons in four different institutions.

Defibrillators, Implantable↗
PubMed1991

Current indications, risks, and outcome after pericardiectomy.

A retrospective analysis of the records of 60 patients who underwent pericardiectomy over a 10-year period (1980 to 1990) at The Johns Hopkins Hospital was performed. Indications for operation were effusive disease in 24 patients and constriction in 36 patients. Six patients (10%) with pericardial effusion had pain as the primary symptom necessitating intervention. The operative approach for pericardiectomy was median sternotomy in 52 patients (4 patients required cardiopulmonary bypass) and left anterior thoracotomy in 8 patients. Nine patients (5 with constriction and 4 with effusion) with a prior limited pericardial procedure required formal pericardiectomy. The operative mortality rate for pericardial effusion and constriction was 4.2% and 5.6%, respectively. Follow-up (median follow-up, 56.9 +/- 38.2 months) was obtained on 56 patients (93.3%). Actuarial survival at 1 year, 5 years, and 10 years for all patients was 82.1% +/- 5.1%, 71.7% +/- 6.7%, and 59.8% +/- 12.2%, respectively. A Cox proportional hazards regression analysis was performed using 20 clinical variables. A history of malignancy, previous pericardial procedure, and preoperative New York Heart Association class IV were found to be predictors of poor survival. All patients who underwent operation primarily for effusion with associated pain are alive and have improved functional capacity without steroid use. We conclude that pericardiectomy can be performed with low mortality and can result in good long-term survival and improved functional capacity. Patients who are seen primarily with pain refractory to steroid therapy can be relieved of symptoms with operation.

Actuarial Analysis↗
PubMed1991

The effect of pentobarbital anesthesia on the autonomic nervous system control of heart rate during baroreceptor activation.

This study determined the influence of pentobarbital anesthesia on the autonomic nervous system control of baroreceptor mediated reflex bradycardia in the rat. Reflex bradycardia was elicited by phenylephrine-induced hypertension in conscious and pentobarbital anesthetized (PA) rats before and after sympathetic blockade with the beta-1 receptor antagonist atenolol or parasympathetic blockade with the peripherally acting muscarinic receptor antagonist methyl-atropine. Reflex bradycardia was significantly decreased by pentobarbital anesthesia. Cardiosympathetic blockade produced equivalent relative decreases in baroreflex gain in conscious and PA rats. In contrast, parasympathetic nervous system blockade with methyl-atropine produced relatively less inhibition of baroreflex gain in the PA rat compared with the conscious rat. These results suggest that pentobarbital anesthesia decreases baroreflex gain by inhibiting vagally mediated reflex bradycardia.

Anesthesia, General↗
PubMed1991

Voluntary human immunodeficiency virus testing: acceptance levels and identification of seropositive individuals.

Of 4340 clients of a clinic for those with sexually transmitted diseases who were eligible for voluntary, confidential, serologic testing for the human immunodeficiency virus, 4246 (97.8%) consented to testing; 23 (0.5%) were seropositive. Of 94 persons who declined voluntary testing but who were tested in a blinded study, nine (9.6%) were seropositive. Seropositive persons who declined voluntary testing did not conceal their association with a risk group, while only 61% of seropositive individuals who accepted voluntary testing admitted to inclusion in a risk group before the test. Voluntary testing appears to be insufficient, because 28% of the seropositive individuals were not identified as being seropositive; also, there was a significant deficiency associated with identification of risk at pretest counseling among persons agreeing to voluntary testing.

AIDS Serodiagnosis↗
PubMed1990

Routine use of the left internal mammary artery graft in the elderly.

Left internal mammary artery (LIMA) grafts have better long-term patency rates than do saphenous vein grafts and result in improved late survival. The present study was undertaken to assess the results of LIMA grafting in the elderly. From 1980 through 1988, 723 patients 70 years of age or older had isolated coronary artery bypass grafting performed. During the first 5 years, only 11% of the elderly patients received LIMA grafts, whereas 86% having coronary artery bypass grafting since 1985 had LIMA grafts. Since 1986, LIMA use in the elderly has become routine, with 92% of patients receiving internal mammary artery grafts. During the first 5 years, elderly patients had a hospital mortality rate of 9.3%. Since 1985, the hospital mortality rate fell to 5.5%. In addition, the occurrence of major surgical complications was either unchanged or reduced in patients receiving LIMA grafts. Furthermore, late follow-up indicates a significantly improved 4-year survival rate in patients with internal mammary artery grafts compared with those without: 86 +/- 0.02% versus 77 +/- 0.03% (p less than 0.01). Analysis of multiple potential risk factors for early mortality was performed using multiple logistic regression and late survival using the Cox proportional hazards model. Although unmeasured predictor variables may confound retrospective analyses, LIMA grafting appears to be an independent predictor both of improved early and late survival.

Aged↗
PubMed1988

Impending sudden cardiac death: treatment with myocardial revascularization and the automatic implantable cardioverter defibrillator.

Myocardial revascularization and implantation of the automatic implantable cardioverter defibrillator (AICD) have individually been shown to improve survival in patients after sudden cardiac death. Their combined role has not been well defined. Twenty-three survivors of sudden death underwent revascularization and AICD implantation at an average age of 59 years. The initial arrest was caused by ventricular fibrillation in 15 and ventricular tachycardia in 8. Exercise stress tests, ambulatory ECGs, and electrophysiological monitoring with programmed electrical stimulation were done preoperatively and postoperatively. Follow-up averaged 24 months with a two-year survival of 91%. Eight patients (35%) required AICD resuscitation an average of 8 months postoperatively, and electrophysiological testing did not accurately predict arrhythmia recurrence. The addition of AICD implantation to revascularization substantially improves survival of patients with sudden cardiac death.

Adult↗
PubMed1988

Aortic valve selection in the elderly patient.

To determine the influence of valve selection on valve-related morbidity and mortality and patient survival, comparative long-term performance characteristics of mechanical (N = 68) and bioprosthetic (N = 73) heart valves were analyzed for 141 patients more than 70 years old who underwent isolated aortic valve replacement between 1970 and 1985. Cumulative patient follow-up was 491 patient-years (average, 4.3 years per patient). Hospital mortality was 18% and 19% for patients with mechanical valves and bioprosthetic valves, respectively. Survival at 5 years was 61 +/- 7% (+/- the standard error) and 67 +/- 10% for recipients of mechanical valves and bioprosthetic valves, respectively. Male sex (p = 0.014) and urgency of operation (p = 0.006) were independent risk factors for hospital mortality. Atrial fibrillation increased valve-related mortality (p = 0.01). No patient required reoperation or experienced structural valve failure. While anticoagulant-related hemorrhage was increased in recipients of mechanical valves (9.2 +/- 2.1%/patient-year) compared with recipients of bioprosthetic valves (2.3 +/- 1.1%/patient-year), it did not result in a death or lead to permanent disability. There was no difference in freedom from any valve-related complication at 5 years. However, when all morbid events are considered, recipients of bioprosthetic valves experienced fewer valve-related complications than patients receiving mechanical valves (10.7 +/- 2.3%/patient-year versus 17.6 +/- 2.5%/patient-year, respectively; p less than 0.05). The reduced incidence of anticoagulant-related hemorrhage and the infrequent need for warfarin sodium anticoagulation favor selection of a bioprosthetic heart valve in patients older than 70 years.

Aged↗
PubMed1988

Implantation of the automatic implantable cardioverter defibrillator.

Since February 1980 the automatic implantable cardioverter defibrillator has been implanted in over 1,500 patients. Sudden death rates have been reduced to 2%-4% annually. This report reviews the implantation techniques, their indications, and our clinical experience in 200 patients.

Arrhythmias, Cardiac↗