Showing papers by "University of Texas Health Science Center at Houston published in 1980"

Rate of gene silencing at duplicate loci: a theoretical study and interpretation of data from tetraploid fishes.

Abstract: A large-scale simulation has been conducted on the rate of gene loss at duplicate loci under irreversible mutation. It is found that tight linkage does not provide a strong sheltering effect, as thought by previous authors; indeed, the mean loss time for the case of tight linkage is of the same order of magnitude as that for no linkage, as long as Nu is not much larger than 1, where N is the effective population size and u the mutation rate. When Nu is 0.01 or less, the two loci behave almost as neutral loci, regardless of linkage, and the mean loss time is about only half the mean extinction time for a neutral allele under irreversible mutation. However, the former becomes two or more times larger than the latter when Nu ≥ 1.——In the simulation, the sojourn times in the frequency intervals (0, 0.01) and (0.99, 1) and the time for the frequency of the null allele to reach 0.99 at one of the two loci have also been recorded. The results show that the population is monomorphic for the normal allele most of the time if Nu ≤ 0.01, but polymorphic for the null and the normal alleles most of the time if Nu ≥ 0.1.——The distribution of the frequency of the null allele in an equilibrium tetraploid population has been studied analytically. The present results have been applied to interpret data from some fish groups that are of tetraploid origin, and a model for explaining the slow rate of gene loss in these fishes is proposed.

Physical Illness Manifesting as Psychiatric Disease: II. Analysis of a State Hospital Inpatient Population

Abstract: • One hundred patients of lower socioeconomic class were intensively evaluated medically on a research ward for the presence of unrecognized medical illnesses that might have affected their hospitalization. Forty-six percent were thought to have medical illnesses that directly caused or greatly exacerbated their symptoms and were consequently responsible for their admission, while an additional 34% of patients were found to be suffering from a medical illness requiring treatment. A diagnostic battery of physical, psychiatric, and neurologic examinations, coupled with a 34-panel automated blood analysis, complete blood cell count, urinanalysis, ECG, and sleepdeprived EEG established the presence and nature of more than 90% of the illnesses detected, and is therefore recommended as an initial evaluation battery, particularly for patients facing involuntary commitment to a mental hospital.

Delayed and Recurrent Intracranial Hematomas Related to Disseminated Intravascular Clotting and Fibrinolysis in Head Injury

Abstract: Twelve delayed or recurrent intracranial hematomas were seen in 340 patients with head injuries. Eleven of these hematomas were associated with clotting abnormalities suggesting disseminated intravascular clotting and fibrinolysis (DICF). Seven of 8 delayed traumatic intracerebral hematomas were associated with clotting abnormalities. Two of these were at ventriculostomy sites, which suggests an increased risk of bleeding in association with the insertion of ventricular catheters in patients with DICF. There were 2 delayed epidural hematomas, 1 under a fracture and the other on the side opposite a craniotomy that had been made to treat an intracerebral hematoma, and there were 2 postoperative epidural hematomas. No postoperative hematomas occurred in the absence of DICF. DICF is a major factor in the development of delayed and recurrent intracranial hematomas in patients with head injuries.

Primate memory: retention of serial list items by a rhesus monkey

Abstract: A rhesus monkey correctly recognized 86 and 81 percent of 10- and 20-item lists, respectively. It serial position curve was similar in form to a human's curve, revealing prominent primacy and recency effects. The key to these findings was in minimizing proactive interference through the use of a large pool of 211 color photographs.

Antimutagenic activities of common vegetables and their chlorophyll content

Abstract: Aqueous and acetone extractions of some common vegetables inhibited the activation of 3-methylcholanthrene and benzo[ a ]pyrene in the Ames Salmonella gene reversion mutagenesis/mammalian microsomal activation assay. The potency of the inhibitory activity was correlated with the chlorophyll content of the acetone extracts. The aqueous fractions contained sufficient histidine to interfere with the interpretation of the result. However, grouping the aqueous extracts from vegetables yielding low, medium, and high levels of histidine allowed comparison between antimutagenic activity and chlorophyll content. Increasing chlorophyll contents corresponded to increasing antimutagenic activities in all 3 groups. Sodium copper chlorophyllin demonstrated comparable inhibitory activity when compared at the same chlorophyll level.

Statistical Studies on Protein Polymorphism in Natural Populations. III. Distribution of Allele Frequencies and the Number of Alleles per Locus

Abstract: With the aim of understanding the mechanism of maintenance of protein polymorphism, we have studied the properties of allele frequency distribution and the number of alleles per locus, using gene-frequency data from a wide range of organisms (mammals, birds, reptiles, amphibians, Drosophila and non-Drosophila invertebrates) in which 20 or more loci with at least 100 genes were sampled. The observed distribution of allele frequencies was U-shaped in all of the 138 populations (mostly species or subspecies) examined and generally agreed with the theoretical distribution expected under the mutation-drift hypothesis, though there was a significant excess of rare alleles (gene frequency, 0 ~ 0.05) in about a quarter of the populations. The agreement between the mutation-drift theory and observed data was quite satisfactory for the numbers of polymorphic (gene frequency, 0.05 ~ 0.95) and monomorphic (0.95 ~ 1.O) alleles.—The observed pattern of allele-frequency distribution was incompatible with the prediction from the overdominance hypothesis. The observed correlations of the numbers of rare alleles, polymorphic alleles and monomorphic alleles with heterozygosity were of the order of magnitude that was expected under the mutation-drift hypothesis. Our results did not support the view that intracistronic recombination is an important source of genetic variation. The total number of alleles per locus was positively correlated with molecular weight in most of the species examined, and the magnitude of the correlation was consistent with the theoretical prediction from mutation-drift hypothesis. The correlation between molecular weight and the number of alleles was generally higher than the correlation between molecular weight and heterozygosity, as expected.

Relationships between environmental factors, bacterial indicators, and the occurrence of enteric viruses in estuarine sediments

Abstract: Current standards for evaluation of the public health safety of recreational and shellfish-harvesting waters are based upon bacteriological analysis, but do not include an evaluation of the number of viruses. The objective of this study was to determine the occurrence of enteric viruses in estuarine sediments and to find a relationship, if any, between the presence of viruses in seawater or sediment or both and various biological and physicochemical characteristics of the environment. Viruses were found in greater numbers in sediment than in overlying seawater on a volume basis. Several types of enteroviruses were isolated: coxsackievirus types A16, B1, and B5, echovirus type 1, and poliovirus type 2. On several occasions, viruses were isolated from sediments when overlying seawaters met bacteriological water quality standards for recreational use. Statistical analysis of the relationship between viruses in seawater or in sediment and other variables measured yielded only one significant association: the number of viruses in sediment was found to be positively correlated with the number of fecal coliforms in sediment. No other physical, chemical, or biological characteristic of seawater or sediment that was measured showed statistically significant association with viral numbers. No correlation was found between bacterial indicators and virus in the overlying waters. The data indicated that evaluation of the presence of bacteria and viruses in sediment may provide additional insight into long-term water quality conditions and that indicator bacteria in water are not reflective of the concentration of enteric viruses in marine waters.

Plasma cholesterol and triglyceride distributions in 13,665 children and adolescents: the prevalence study of the Lipid Research Clinics Program.

Abstract: Summary: The age-, race-, and sex-specific distributions for plasma cholesterol (CH) and triglyceride (TG) are described for the 13,655 individuals under 20 years of age who were examined at the first visit (visit I) of the Prevalence Study of the Lipid Research Clinics (LRC) Program. Composite findings are presented from the seven North American LRC's where children were included in the target population. Cholesterol values are higher for blacks than for whites, but triglyceride values are higher for whites than for blacks. In both the CH and TG distributions for the combined races, the mean values for females are generally higher than for males. For cholesterol, consistent age-associated differences occur. On average, the CH values peak in late childhood and decline during adolescence. The decrease in mean values for CH is most marked for white males. The values for TG tend to increase in early adolescence. This report expands the available information about lipid distributions in young populations and describes the extent of the variation in plasma lipids associated with race and sex for each year of age, 0 to 19 years. Speculation: The pattern of age-associated differences found in these population-based, cross-sectional surveys points to the need for prospective studies of lipid levels in cohorts examined before puberty and followed throughout adolescence and into early childhood. Such longitudinal studies may reveal the biological explanation for the age-curve of the mean values for lipids.

Prevention of traveler's diarrhea (emporiatric enteritis). Prophylactic administration of subsalicylate bismuth).

Abstract: The efficacy of a daily dosage regimen of subsalicylate bismuth in preventing or reducing the severity of diarrhea among young healthy adults was evaluated in a double-blind, randomized, placebo-controlled trial Diarrhea developed in 14 (23%) of 62 students receiving subsalicylate bismuth compared with 40 (61%) of 66 students taking a placebo The protective effect of subsalicylate bismuth was apparent within a day or two of the study onset and became more obvious as the number of days at risk increased The students treated with subsalicylate bismuth experienced fewer intestinal complaints and were less likely to pass soft or watery stools of any number Once diarrhea occurred, enteropathogens were less commonly identified in stools of students receiving subsalicylate bismuth (33%) compared with placebo (71%) Subsalicylate bismuth was well tolerated by students during the 21-day trial ( JAMA 243:237-241, 1980)

Diagnosis of Leukemia or Lymphoma in the Central Nervous System by Beta2-Microglobulin Determination

Abstract: To detect early relapse in the central nervous systems (CNS) of patients with acute leukemia or lymphoma, we measured levels of beta 2-microglobulin (beta 2 m) in serum and cerebrospinal fluid (CSF). CSF levels were significantly higher in patients with leukemia (P < 0.001) or lymphoma (P < 0.02) with clinical evidence of CNS involvement than in those without this complication. When serum and CSF levels were measured simultaneously, the CSF level of beta 2 m was significantly higher than the serum level in patients with acute leukemia and lymphoma with CNS involvement (P = 0.05), but not in patients without CNS involvement. Serial determination of CSF beta 2 m correlated well with the clinical appearance and disappearance of CNS involvement. These data suggest that serial and simultaneous determination of beta 2 m in serum and CSF may be useful in early diagnosis of CNS involvement and in monitoring intrathecal therapy in patients with acute leukemia or lymphoma.

Characterization ofAlteromonas hanedai (sp. nov.), a nonfermentative luminous species of marine origin

Abstract: Eleven marine luminous isolates, which could not be identified with previously studied species of luminous marine bacteria, were subjected to an extensive characterization. The results indicated that these strains were phenotypically similar, had a G+C content in their DNA of 45 mol%, and differed from all previously characterized luminous species by their inability to ferment sugars. On the basis of these and other properties, the 11 luminous strains were assigned to the genusAlteromonas and given the species designationA hanedai. Strain 281 (ATCC 33224) has been designated as the type strain of this new species.

Environmentally acquired lead, cadmium, and manganese in the cattle egret, Bubulcus ibis, and the laughing gull, Larus atricilla.

Abstract: The concentrations of lead, cadmium, and manganese in the tissues of cattle egrets (Bubulcus ibis) and laughing gulls (Larus atricilla) gathered from the Galveston Bay region of Texas were compared, to determine if different patterns of accumulation exist. Their levels in these species were within the range reported for other bird species. Lead levels in bone were comparable, but gulls had more lead in brain, kidney and liver tissues than the egrets, which suggested a higher rate of accumulation or exposure. Due to their high abundance and comparable positions in the estaurine and terrestrial food webs, it is suggested that Bubulcus ibis and Larus atricilla may serve as convenient biological indicators to monitor potentially toxic substances in these ecosystems.

Non-random association between electromorphs and inversion chromosomes in finite populations

Abstract: With the aim of knowing the probable magnitude of non-random association between inversion chromosomes and electromorphs, both deterministic and stochastic studies are conducted on the evolutionary change of non-random association, which is defined as the difference in the frequency of a given allele between inversion and non-inversion chromosomes. In these studies inversion chromosomes are assumed to be subject to selection but electromorphs are selectively neutral, and recombination is allowed to occur between inversion and non-inversion chromosomes with a low frequency. The deterministic study has shown that in a variety of selective schemes for inversion chromosomes the non-random association decays at a rate equal to the recombination value in every generation. Thus, if the recombination value is of the order of 10−5 ˜ 10−4, it would take a long time for the non-random association to disappear. Furthermore, the stochastic study has indicated that random genetic drift generates non-random association of inversions and electromorphs in finite populations and the standard error of non-random association often becomes larger than the mean. In addition to these problems the time required for the electromorph frequencies in the inversion and noninversion chromosomes to become equal in a finite population and the probability that the population of inversion chromosomes remains monomorphic for the allele which existed in the initial inversion introduced are studied. Considering all these quantities, it is concluded that data on the non-random association between electromorphs and inversions are not very informative for the study of the maintenance of protein polymorphism. It is also indicated that in the study of association between electromorphs and inversion chromosomes non-random association or Yule's coefficient of association has a better property than the usual linkage disequilibrium measure or correlation coefficient. Implications of this study on some experimental observations are discussed.

Chronobiometry with pocket calculators and computer systems.

Abstract: Selected methods for the study of biologic time series are reviewed and their relative merits are discussed in the light of underlying assumptions. Their potential applications are exemplified in several fields of biology and medicine. The monitoring of environmental integrity, notably of pollution, is investigated. The need for specifying optimal sampling requirements is underlined. An individualized and time-qualified definition of health by the establishment of reference intervals is required for increasingly rational individualized program for the prevention and/or treatment of disease. With these reference intervals and rhythm characteristics available, one can better interpret with single samples or time series an increased risk of a certain disease or the inception of the disease. For all of these aims the monitoring of environmental and/or personal marker rhythms is essential--to obtain large data bases from which information can be more easily derived for monitoring personal health, to recognize risk as well as to diagnose disease early and to optimize treatment by timing according to rhythms.

Antiepileptic Effects of Melatonin in the Pinealectomized Mongolian Gerbil

Abstract: Summary: Pinealectomy of the Mongolian gerbil leads to seizure activity. The pineal gland is a major source of melatonin (5-methoxy-N-acetyltryptamine) which may possess a modulatory influence upon neural activity. Melatonin administered in the form of subcutaneous beeswax implants was given to ger-bils four days prior to pinealectomy or sham pinealectomy. Beeswax pellets were implanted as the vehicle agent in respective groups. Melatonin-treated pinealectomized animals exhibited fewer seizures than did pinealectomized animals that did not receive melatonin. The results indicate that melatonin has an ameliorative effect upon pinealectomy-induced seizures, but the mechanism by which pinealectomy induces the seizures, and the etiology in which melatonin reduces the seizure activity is unknown. RESUME La pinealectomie provoque la survenue de crises chez la Gerbille Mongolienne. La glande pineale est la source principale de melatonine (5-methoxy-N-acetyltryptamine) qui semble posseder une influence modulatrice sur l'activite des neurones. La melatonine est administree a des Gerbilles sous forme d'implants de cire d'abeille sous-cutanes, 4 jours avant une pinealectomie reelle ou simulee. Des pellets de cire d'abeille sans melatonine sont implantes dans des groupes temoins. Les animaux pinealectomises, traites avec la melatonine ont presente moins de crises que les autres. Ces resultats indiquent que la melatonine agit efficacement contre les crises provoquees par la pinealectomie, mais les mecanismes par lesquels cette intervention provoque les crises et par lesquels la melatonine reduit cette activite critique sont inconnus. RESUMEN La extirpacion de la pineal en roedores mongo1icos dio origen a actividad comicial. La glandula pineal es una fuente mayor de melatonina (5-metoxi-N-acetil-triptamina) la cual puede tener una influencia mod-uladora sobre la actividad neuronal. Se administro melatonina en forma de implantes subcutaneos de cera de abejas a los roedores cuatro dias antes de Uevar a cabo una pinealectomia o una “pinealectomia simulada”. Las capsulas de cera de abeja fueron utilizadas como vehiculo agente en grupos respec-tivos. Los animales pinealectomizados tratados con melatonina mostraron menos ataques que los animales pinealectomizados que no recibieron melatonina. Los resultados indican que la melatonina tiene un efecto beneficioso sobre los ataques inducidos por la pinealectomia aunque el mecanismo por el cual la pinealectomia produce crisis y la melatonina reduce la actividad paroxistica permanece desconocido.

The discriminative stimulus properties of 2,5-dimethoxy-4-methylamphetamine (DOM): differentiation from amphetamine.

Abstract: Rats were trained in a two-lever operant procedure to discriminate either 1.0 mg/kg(+)amphetamine or 1.5 mg/kg DOM from saline. Rats trained to discriminate DOM from saline showed generalization with the DOM training condition when tested with mescaline or 2,5-dimethoxy-4-ethylamphetamine (DOET), but not when tested with (+)amphetamine or methylphenidate. Both isomers of DOM generalized with racemic training compound, the (-)isomer being more potent. The DOM stimulus was completely blocked by the serotonin (5-HT) antagonists cinanserin and methysergide, but not by the peripheral 5-HT antagonist xylamidine nor the dopamine antagonist haloperidol. Rats trained to discriminate (+)amphetamine from saline generalized with the amphetamine training condition when tested with methylphenidate but not when tested with mescaline, DOET, racemic DOM, or either isomer of DOM. The amphetamine stimulus was blocked by pretreatment with haloperidol but not by cinanserin, methysergide, or xylamidine. The results show that, despite their structural similarity, amphetamine and DOM induce pharmacologically distinct stimuli.

Effects of fasting on uterine blood flow and substrate uptake in sheep.

Abstract: Twelve chronically instrumented late-gestation ewes fasted for 5 days were found to have a 25% decrease in total uterine blood flow and a 20% decrease in placental blood flow. Cardiac output was unchanged but was redistributed, as measured by radiolabeled microspheres, in a pattern similar to that produced by catecholamines. Fasting also was associated with hypoglycemia and altered whole blood amino acid concentrations. Uterine uptakes of glucose, oxygen, essential amino acids and glutamine, an important uterine and fetal nutrient, were decreased significantly during fasting. The increased hepatic blood flow and decreased arterial concentrations of glucogenic amino acids observed during fasting are consistent with a redistribution of maternal cardiac output to support maternal hepatic gluconeogenesis at the expense of nutrient supply to the gravid uterus.

Medical care use by mexican-americans: Evidence from the human population laboratory studies

Abstract: Data are presented from sample surveys conducted in 1974 (N = 3,119) and 1975 (N = 657) in Alameda County, California, by the Human Population Laboratory. Mexican-Americans are compared to Anglos and blacks in terms of physician visits, dental examinations, general physical examinations, and eye examinations. Comparison of crude percentages indicates that there is very little ethnic variation in either sample regarding regular source of medical care or health insurance coverage, although the trend is for fewer Chicanos to have such coverage. In terms of physician visits, there is little difference between Anglos and Chicanos. By contrast, fewer Chicanos and blacks report dental examinations in the past year (Chicanos have the lowest rate). Fewer Chicanos report a general medical examination in the past year and more report never having had a medical checkup. Likewise, more Chicanos report never having an eye examination while relatively fewer report such an exam in the past year. Controlling for the effects of age, sex, education, family income, health insurance, regular source of care, physical health status and perceived health reduces differences in rate of physician visits among the ethnic groups, primarily by reducing the rate for blacks and increasing the rate for Chicanos. Likewise, adjustment for all 8 factors reduces ethnic differences in general medical examination rates, in this case by increasing the rates for the minority groups. Adjustment reduces the ethnic differences in dental examination rates by increasing the minority group rates, but large differences still remain. For eye examinations, adjustment has little effect on the rates for Anglos and blacks, but substantially increases the rate for Chicanos. For all 4 types of medical care behavior, controlling for the effects of education and family income (so-called inequitable reasons for lower access to care) consistently produces the greatest effect, particularly for Chicanos. In each case, the effect is to create greater parity between Chicanos and Anglos by increasing the utilization rate for Chicanos. However, even after adjustment, the rate for Chicanos remains lower.

Retrospective analyses of the need for mechanical circulatory support (intrasortic balloon pump/abdominal left ventricular assist device or partial artificial heart) after cardiopulmonary bypass. A 44 month study of 14,168 patients.

Abstract: Data on 14, 168 adult patients undergoing surgery in the 44 months from November 1, 1975 to July 1, 1979 were analyzed to determine the incidence of need for escalating degrees of mechanical support of the failing circulation (intraaortic balloon pump, abdominal left ventricular assist device, or both) after cardiopulmonary bypass. Analyses were performed using a TRS-80 microcomputer to categorize the postoperative course of all adult patients undergoing open heart surgery. It was assumed that any patient who died despite pharmacologic and intraaortic balloon support was a candidate for more profound mechanical circulatory support, that is, the left ventricular assist device, which is 6 to 10 times more hemodynamically effective; on this basis, the latter device was needed in 430 cases (3 percent). A total of 12,669 patients (89.4 percent) were weaned from bypass without difficulty, 1,499 patients (10.6 percent) required pharmacologic agents and volume loading during weaning, 326 patients (2.3 percent) demonstrated inadequate responses to conventional pharmacologic therapy and required intraaortic balloon support during weaning, 94 patients (0.7 percent) demonstrated an inadequate response to conventional pharmacologic and balloon support and 21 patients (0.1 percent) underwent profound mechanical circulatory support (abdominal implantation of a left ventricular assist device).

Genetic manipulation by means of microcell-mediated transfer of normal human chromosomes into recipient mouse cells

Abstract: Microcell-mediated chromosome transfer is an innovative approach to the production of karyotypically simple hybrids. This method of gene transfer, employing micronuclei formed by prolonged Colcemid treatment, has been utilized for rodent systems. Expansion of this technology to include transfer of normal human genetic material has been hindered because large micronucleate populations from diploid human cells have been unobtainable. This report describes the production of micronuclei in 40-60% of normal human fibroblasts. These micronucleated cells have been enucleated by combining centrifugation and cytochalasin B treatment, and the resultant microcells have been purified and fused to recipient mouse (LMTK-) cells. Microcell hybrid clones containing a single human chromosome have been isolated from three separate fusion experiments. The time course for production of these hybrids, from fusion to karyotypic analysis, was 6 weeks. With a transfer frequency of about 2 x 10(-6), a single intact human chromosome has become a functioning element of the murine genome.

Human colostral cytotoxicity. II. Relative defects in colostral leukocyte cytotoxicity and inhibition of peripheral blood leukocyte cytotoxicity by colostrum.

Abstract: Colostral cells have been previously shown to mediate antibody-dependent cellular cytotoxicity (ADCC) to herpes to simplex virus-infected cells. A comparison of colostral cells to matched peripheral blood mononuclear cells has revealed significantly lower ADCC activity, higher antibody requirements, and slower kinetics of colostral cell ADCC against infected cells. Colostral cells failed to mediate natural killer cytotoxicity. Lymphocytes, monocyte macrophages, and polymorphonuclear leukocytes isolated from peripheral blood and incubated with colostrum from virus-immune or nonimmune women markedly inhibited ADCC. Inhibitory activity was found in lipid and aqueous fractions and was due to an effect on leukocytes, not target cells. A partial explanation was inhibition of expression of leukocyte Fc receptors, a prerequisite for ADCC, by acellular colostrum. These results raise questions concerning the potential antiviral activity of colostral cells in vitro.

Autosomal dominant aniridia: probable linkage to acid phosphatase-1 locus on chromosome 2

Abstract: Maximum likelihood analysis for linkage between autosomal dominant aniridia and 12 biochemical and serological markers in a single large family showed a probable linkage between autosomal dominant aniridia and the enzyme acid phosphatase-1. The presence of an autosomal dominant aniridia gene linked to acid phosphatase-1 on chromosome arm 2p and the existence of an aniridia syndrome resulting from deletion of band 13 of the short arm of chromosome 11 establishes a chromosome basis for genetic heterogeneity of aniridia phenotypes.

Treatment of postoperative low output syndrome with intraaortic balloon pumping: experience with 419 patients.

Abstract: Four hundred nineteen patients with postoperative low output syndrome were supported with intraaortic balloon pumping between September 1, 1972 and June 1, 1979. Overall, 226 patients (54 percent) were successfully weaned from pumping support and 188 (45 percent) were subsequently discharged from the hospital. Approximately 10 percent of the patients died after apparently successful weaning from the balloon pump. Patients who underwent aortocoronary bypass operations had significantly better survival rates than patients who underwent combined aortocoronary bypass and valve procedures (60 versus 28 percent, p < 0.01). Two hundred sixty-three of the 419 patients have been serially classified hemodynamically since 1975. During intraaortic balloon pumping, 134 of these 263 patients ultimately achieved and maintained class A hemodynamic status (cardiac index greater than 2.1 liters/min, with systemic vascular resistance less than 2, 100 dynes s cm−5); all of these patients were successfully weaned from the balloon pump. Fortyone (16 percent) of the 263 patients achieved only class B status (cardiac index greater than 1.2 but less than 2.1 liters/min, systemic vascular resistance less than 2, 100 dynes s cm−5); the mortality rate in this group was 46.3 percent. Eighty-eight of the 263 patients failed to progress beyond class C status (cardiac index less than 1.2 liters/min or systemic vascular resistance greater than 2, 100 dynes s cm−5); the mortality rate was 96.6 percent during intraaortic balloon pumping. The differences in survival rates among patients in classes A, B and C were statistically significant (p < 0.001). The mean ages of survivors and nonsurvivors were not significantly different. Men had a 59 percent and women a 47.3 percent survival rate (p < 0.05). The duration of support was 60.2 ± 44.7 hours in survivors and 10.9 ± 21.1 hours in nonsurvivors, suggesting an early high attrition rate for unsuccessful postoperative support. Patients with balloons of 40 and 30 ml had significantly better survival rates (67 and 52 percent, respectively) than patients with 20 ml balloons (47 percent, p < 0.05).