Adverse 5-year outcome after coronary artery bypass surgery in blacks

BACKGROUND

Coronary heart disease is the leading cause of death among blacks, but little is known about the late results of coronary artery bypass surgery in this population. It is not known whether differences in preoperative medical characteristics or medical health insurance affect outcome. We studied the effects of medical risk factors on survival outcome after coronary artery bypass surgery in a population of medically insured black and white patients.

METHODS

Racial status and outcomes from surgery were determined in 3728 consecutive patients who had coronary artery bypass surgery at the authors' institution from January 1, 1984, to June 30, 1992. Coronary artery bypass surgery (excluding valve replacement) was performed in 115 black and 3113 white patients.

RESULTS

Late survival probability was worse for blacks than whites at 1 year (84% vs 92%) and at 5 years (64% vs 82%, P=.001, Wilcoxon test). Most deaths were due to cardiac events in both groups (68% in blacks vs 67% in whites). Blacks had more hypertension (84% vs 54%), diabetes mellitus (36% vs 23%), and more were current smokers (21% vs 14%) (all P<.05, Fisher's exact test). Medical insurance coverage for blacks and whites was as follows: Medicare (60% vs 57%), private (38% vs 42%), and Medi-Cal (2% vs 2%). Operative mortality (30 days) was similar (5.2% for blacks vs 4.1% for whites; P=.48, Fisher's exact test). In a Cox regression model, race predicted long-term survival and persisted as an important risk factor after adjusting for preoperative factors related to patient survival (adjusted hazard ratio, 2.10; 95% confidence interval, 1.43 to 3.07).

CONCLUSIONS

In this group of predominantly medically insured patients undergoing coronary artery bypass surgery, the risk of death in blacks at 5 years was twice that of whites.

Long-term survival after coronary artery bypass grafting

The most quoted long-term outcome studies from the coronary artery bypass surgery literature were performed in the 1970s, and these trials--the Coronary Artery Surgery Study, the Veterans Administration Study, and the European Cooperative Study--added significantly to our knowledge of the efficacy of bypass surgery. However, important studies are still being performed and are refining our knowledge of long-term outcomes. This review covers early factors that affect long-term outcome, and recent information concerning particular subgroups of patients undergoing bypass surgery. In addition, new information is becoming available about the relative roles of percutaneous transluminal coronary angioplasty and coronary artery bypass grafting, and these studies are also discussed.

A radiological study of abdominal tuberculosis in a Saudi population, with special reference to ultrasound and computed tomography

The radiological appearances of abdominal tuberculosis are presented, which includes peritoneal, liver, spleen and pancreatic disease, but excludes renal and musculoskeletal involvement. Twenty-three patients were studied, 12 of whom had TB peritonitis. Barium studies remain valuable in gastrointestinal tract disease but for peritoneal, splenic, hepatic and pancreatic disease, ultrasound and computed tomography are indicated. Their diagnostic value is further enhanced by guided aspiration and biopsy techniques.

Action potential alternans and irregular dynamics in quinidine-intoxicated ventricular muscle cells. Implications for ventricular proarrhythmia

BACKGROUND

Cardiac cells display rate-dependent beat-to-beat variations in action-potential duration (APD), action potential amplitude (APA), and excitability during periodic stimulation. We hypothesized that quinidine causes a marked increase in the variability of APD, APA, and excitability of ventricular cells isolated from quinidine-toxic, arrhythmic ventricles.

METHODS AND RESULTS

Action potentials were recorded from right ventricular endocardial tissues (2 x 1 cm, < 2 mm thick) isolated from dogs in which ventricular tachycardia and ventricular fibrillation (VT/VF) were induced with intravenous quinidine (80-100 mg/kg) over a 5-hour period in vivo (n = 7). As the basic cycle length (BCL) of stimulation was progressively shortened, rate-dependent variations in APD and APA occurred. The initial dynamic change was alternans of APD and APA that could be either in or out of phase between two cells. The magnitude of alternans was a function of the BCL and the strength of the stimulation current. At critically short BCLs, irregular APD and APA behavior emerged in the quinidine-intoxicated cells. In control cells (n = 16) isolated from three nontreated dogs, APD and APA remained constant at all BCLs tested (2,000-300 msec). Quinidine increased the slope of the APD restitution curve compared with control. The observed quinidine APD restitution curve was fitted with a biexponential equation, and computer simulation using the fitted restitution curve reproduced the aperiodic APD seen in the quinidine toxic cells during periodic stimulation. Thus, the observed irregular APD behavior was predictable from the restitution curve.

CONCLUSIONS

Quinidine toxicity increases the temporal and spatial variability of APD and APA in the ventricle that may promote the initiation of reentrant VT/VF in vivo. The slope of the APD restitution curve provides a method to quantitate inhomogeneities in repolarization time and could be a useful marker for proarrhythmia.

Measurement of stress in clinical nursing

The Nurse Stress Checklist was developed to measure stress in clinical nursing as a multidimensional construct. The instrument was formulated within a transactional model of stress. The items were derived from five domains thought to contribute to nurse stress in clinical settings and were organized into a questionnaire. Holmes Schedule of Recent Events was included as a validity measure. The instrument was tested on 104 staff nurses working in three institutions in an urban community. Exploratory factor analysis was applied to the 74 items presented to subjects in Likert-type format. Five factors were derived and subjected to psychometric evaluation. Internal consistency reliability for the five factors was good, ranging from 0.80 to 0.91. Means and measures of dispersion supported the potential of the five subscales to discriminate among respondents on the attributes being measured. Intercorrelations of the factors provided evidence of the distinctiveness of the five components of stress, although factor loadings showed some overlap between Personal Reactions and Work Concerns and Work Concerns and Work Completion Concerns. Validity of the factors also was supported by correlations with Holmes' Schedule of Recent Events. Content validity was supported by comparison of these results with findings of other investigators. Limitations of the results are discussed, and recommendations for future work on the instrument are offered.

A dopaminergic cell line variant resistant to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is known to cause parkinsonism by killing dopaminergic neurons; the toxic substance is a metabolite, 1-methyl-4-phenylpyridinium ion (MPP+). PC12 cells, which are dopaminergic, are killed in culture by MPTP and MPP+ but at concentrations much higher than that required to kill affected neurons in vivo. However, at low concentrations (10-100 microM), MPP+ caused an increased production of lactate by PC12 cells. MPP+-treated PC12 cells exhibited decreased mitochondrial respiration. Mitochondria from the treated cells respired normally in the presence of added succinate but not beta-hydroxybutyrate, a finding indicating that MPP+ inhibits the oxidation of some substrates selectively. MPP+ was more effective in killing the cells when glycolysis was reduced with 2-deoxyglucose or by lowering the glucose content of the culture medium. Under these conditions, MPP+ inhibited ATP synthesis and depleted cellular stores of ATP. A PC12 variant that is even more resistant to MPTP and MPP+ than are wild-type cells has been isolated. The MPTP-resistant variant is also more resistant to the lethal effects of oligomycin, antimycin A, and rotenone. This variant exhibited altered lactate production and mitochondrial respiration. It is suggested that some brain neurons that accumulate MPP+ without being killed by it may also have an energy metabolism somewhat different from that of more sensitive neurons.

The value of ultrasound in previously undiagnosed renal failure

Rapid advances in equipment and diagnostic criteria have made ultrasound sufficiently sensitive to replace high-dose urography (with its attendant risks and often lengthy examination time) as the initial imaging modality in renal failure. A prospective study was carried out in 56 patients (109 kidneys). All hydronephroses were accurately detected on ultrasound. 80% were due to obstruction, but showed no features that distinguished them from other causes of hydronephrosis. A diagnostic pathway is suggested.

Inhibition of dopamine uptake by N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, a cause of parkinsonism

N-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine has been reported to cause parkinsonism in man and monkeys, producing behavioral effects within 5 min of administration. The compound reversibly and competively inhibited (IC50 = 2 microM) dopamine uptake into PC12, a clonal line of rat pheochromocytoma cells that store and secrete dopamine and acetylcholine. Uptake of choline and 2-deoxyglucose was not affected. Prolonged exposure to the compound was lethal to PC12; survivors of this treatment lost the ability to store dopamine and acetylcholine and to extend neurites upon incubation with nerve growth factor.

Prolongation of segmental pancreatic allografts in dogs receiving cyclosporin A

This study showed that a heterotopic autotransplant of the tail of the pancreas was capable of maintaining adequate glucoregulatory function in pancreatectomized dogs, glucose tolerance test curves, and K values not differing from normal dogs 4 months after transplantation. Hyperinsulinemia in the fasting state was observed in the absence of hypoglycemia in autograft and allograft recipients. Intraductal Ethibloc injection produced total replacement of the exocrine gland at 4 months by fibrosis but with the preservation of islets. Cyclosporin A (Cy A, oral drinking solution) in a dose of 25 mg/kg/day given to recipients of heterotopic segmental allografts produced a slight but significant prolongation of graft survival, but a dose of 40 mg/kg/day resulted in indefinite graft survival (greater than 100 days) in five of eight allograft recipients. During intravenous glucose tolerance tests (IVGTTs), fasting hyperinsulinemia and significantly impaired glucose degradation (K values) was observed in long-term surviving allograft recipients 4 months after transplantation. In four long-term surviving pancreatic allograft recipients initially given 40 mg/kg/day, the dose of Cy A was gradually reduced after 4 months to a maintenance dose of 5 mg/kg/day by 6 months. On a dose of 5 mg/kg/day, three dogs rejected their grafts between 18 and 28 days after this schedule had commenced. Successful reversal of the hyperglycemia in two of three dogs that rejected their grafts was achieved by i.v. methylprednisolone and increased doses of Cy A. These results indicate that Cy A alone could significantly prolong the survival of canine pancreatic segmental allografts, but initially higher doses were required than that found to be effective in prolonging renal allograft survival in the dog.

Effect of cyclosporin A on allotransplanted pancreatic fragments to the spleen of totally pancreatectomized dogs

Cyclosporin A (Cy A) was evaluated in dogs to assess its effectiveness of prolonging survival of allogeneic pancreatic islet tissue transplanted to the spleens of totally pancreatectomized mongrel dogs. Thirty-seven dogs were made diabetic by total pancreatectomy. Ten untreated pancreatectomized animals survived a mean (+/-SE) of 6.3 +/- 0.9 days and died with mean (+/-SE) plasma glucose levels of 23.2 +/- 2.7 mmol/liter. Dispersed pancreatic fragments, prepared by collagenase digestion without separation of exocrine and endocrine components, were directly implanted into the splenic pulp of 27 pancreatectomized dogs. Twelve dogs given autotransplants became normoglycemic after 4.3 +/- 0.5 days and remained so until killed at 60 days post-transplant, although normal glucose tolerance tests were not achieved. Eight nonimmunosuppressed dogs given allogeneic pancreatic fragments did not become normoglycemic but survived for 13.0 +/- 2.1 days, the dogs dying with a terminal plasma glucose of 22.7 mmol/liter. An additional seven dogs given allogeneic transplants were given Cy A (oral solution), 25 mg/kg/day, for 14 days, and, although failing to become normoglycemic, survived for 28.1 +/- 5.4 days and died with terminal plasma glucose levels of 25.1 +/- 0.6 mmol/liter. Intrasplenic complications included subcapsular hematomas, intrasplenic necrosis and cavitation, capsular perforations, and arteriolar thrombosis. The failure to achieve normoglycemia with allogeneic dispersed pancreatic tissue in dogs treated with Cy A and the complications associated with the implantation of the tissue in the spleen do not suggest that this approach is worthy of clinical trial.

Age-related changes in the immune system of mice of eight medium and long-lived strains and hybrids. I. Organ, cellular, and activity changes

Fifty-three organ, cellular and activity indices were assessed in aging mice of 8 strains and hybrids (5 inbred strains, 1 random bred strain and 2 hybrids of inbred strains) in an attempt to determine which aspects of immunologic aging are characteristic of the species. The results indicate that thymic weight, cellular, and activity indices exhibit a statistically significant negative correlation with age for mice of all 8 strains and hybrids; and B cell cellular indices show a statistically significant positive correlation with age for all mice, while the B cell activity index, lipopolysaccharide response, is dependent on the strain or hybrid. This correlation study supports the view that the T cell component of the immune system deteriorates with age while the B cell component remains relatively intact. Further, the results suggest that thymic aging is a characteristic of the mouse species and that the intrinsic "clock" for immunologic aging resides in the thymus, because most splenic and lymph node T cell activity and cellular indices are associated with thymic weight and cellular indices. Finally, the findings that indices which correlate best with age show the same trend for all strains and hybrids examined suggest that (a) if randomly occurring somatic mutation does play a role in immunologic aging, its influence is limited, and (b) genetic factors not easily influenced by environmental factors regulate immunologic aging.

Lymphocyte sequestration by the liver in alcoholic hepatitis

The possibility that lymphocytes are sequestered by the liver in patients with alcoholic hepatitis was investigated. Sixteen patients who had liver biopsy specimens taken were studied as follows: The T- and B-lymphocyte populations of the peripheral blood and liver biopsy digest were quantitated. The liver biopsy specimens were studied by light and electron microscopy for lymphocyte-hepatocyte interaction. The data were analyzed by comparing the results of patients with and without the presence of Mallory bodies (MBs) in the liver. When MBs were present, the percentage of T cells was significantly increased in the liver compared with peripheral blood. By electron microscopy, two livers with MBs showed lymphocyte-hepatocyte interaction. The results support the concept that lymphocytes participate in a cell-mediated immune process when MBs are present in the liver.