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Biomedical subjects

J Ross

Publications and source records attributed to J Ross.

At least 541 records · Page 30Linked to original sources
PubMed1985

Complex ventricular arrhythmias in patients with Q wave versus non-Q wave myocardial infarction.

We examined whether or not subsets of patients with complex ventricular arrhythmias after myocardial infarction are at high risk with respect to 1 year mortality after hospital discharge. Based on previous studies showing increased risk for those with non-Q wave infarcts, we hypothesized that complex PVCs (premature ventricular complexes) in this group might be associated with a poorer prognosis than complex PVCs in patients with Q wave infarcts. Seven hundred seventy-seven patients entering our study with acute infarction were followed prospectively for 1 year after undergoing a predischarge 24 hr ambulatory electrocardiographic examination. Patients were classified by electrocardiographic criteria into the following groups: Non-Q wave (n = 191), Q wave anterior (n = 261), and Q wave inferior infarction (n = 325). The following arrhythmias were classified as complex: multiform PVCs, couplets, and ventricular tachycardia. Sixty-two percent of patients with non-Q wave infarcts who did not survive 1 year had complex PVCs, compared with 32% of survivors (p less than .01). No differences were seen in the Q wave subgroup. The survival for patients with Q wave and non-Q wave infarction without complex PVCs were nearly identical at 1 year (93% and 90%), whereas in patients with complex PVCs survival for those with Q wave and non-Q wave infarction was 92% and 76%, respectively (p less than .001). Of those with non-Q wave infarction, only 4% of nonsurvivors were free of any PVCs, as compared with 28% of nonsurvivors in the Q wave group (p less than .02).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

H-Y antigen in a 46,XX female with dysgenetic ovaries.

Hypogonadism secondary to ovarian dysgenesis or resistant ovary syndrome was diagnosed in a 19-yr-old obese woman with primary amenorrhea, a 46,XX karyotype, and an H-Y+ cellular phenotype. Small ovoid gonads (1.5 X 0.6 cm) were found found bilaterally; these were encased in a dense venous network. The stroma was ovarian, and primordial follicles and some primary follicles were present, but there were no follicles at or beyond the antrum stage. There was no evidence of testicular tissue and no evidence of malignancy. Analysis of serological data indicated the possibility of residual H-Y antigen in the blood cells of the mother.

Adult↗
PubMed1985

Colonization of hospitalized patients by Staphylococcus aureus, Staphylococcus epidermidis and enterococci.

Patients admitted to a medical intensive care unit (29), a surgical intensive care unit (29) and a general medical ward (34) were studied to determine the frequency of colonization by Staphylococcus aureus, Staph. epidermidis and enterococci. Cultures of anterior nares, pharynx, axilla, periurethral tissues, and rectum were done within 24 h of admission and every 48-72 h thereafter for the duration of hospitalization. We found Staph. aureus colonization of pharynx, axilla, periurethral tissues and rectum to be equally frequent in patients with and without nasal colonization. Staphylococcus epidermidis was commonly recovered from all sites except the pharynx. The 49 strains of this organism acquired in the hospital were significantly more often resistant to nafcillin, cephalothin, chloramphenicol, trimethoprim-sulfamethoxazole and gentamicin than were 199 isolates recovered from patients at the time of admission. Enterococci were commonly isolated from rectal swabs and, less often, from other sites. Acquisition of enterococcal colonization during hospitalization was correlated significantly with antibiotic administration.

Anti-Bacterial Agents↗
PubMed1985

Half-lives of beta and gamma globin messenger RNAs and of protein synthetic capacity in cultured human reticulocytes.

The turnover rates of beta and gamma globin messenger RNAs and of beta and gamma globin protein synthesis in human reticulocytes have been measured. Our goal was to determine whether beta globin mRNA is significantly more stable than gamma globin mRNA during the final stages of erythroid cell maturation. Such a result could explain the reported increase in the beta-gamma protein synthetic ratio during erythroid maturation. As determined by molecular hybridization and cell-free translation assays, the half-lives of both mRNAs are 20 to 29 hours in adult and neonatal reticulocytes. Protein synthetic capacity in intact cells decays with a half-life of six to eight hours, but beta protein synthesis declines at the same rate as gamma. Therefore, the changing ratio of fetal to adult hemoglobin synthesis during late erythroid maturation does not result from differences in mRNA turnover rates or changes in translation efficiencies. These data, coupled with those obtained with immature erythroid cells (Farquhar et al, Dev Biol 85: 403, 1981), suggest that, during erythroid maturation, the gamma-beta globin protein synthesis ratio declines because gamma gene transcription ceases earlier than beta gene transcription. Our results also indicate that the protein synthetic machinery, not the quantity of mRNA, becomes rate-limiting for globin production in cultured reticulocytes.

Adult↗
PubMed1984

Subcellular localization of RNAs in transfected cells: role of sequences at the 5' terminus.

We have investigated the intracellular location of RNAs transcribed from transfected DNA. COS cells transfected with a clone containing the human adult beta globin gene contain three classes of globin RNAs. Their 3' termini and splice sites are indistinguishable from those of mature reticulocyte beta globin mRNA, and they are polyadenylated. However, as determined by S1 mapping, their 5' sequences are different. The 5' terminus of one is the same as that of mature beta globin mRNA (+1, cap site). The presumed 5' terminus of the second is located 30 nucleotides downstream from the cap site (+30). The third class contains additional nucleotides transcribed from sequences located 5' to the cap site (5' upstream RNA). The 5' upstream RNA molecules are restricted to the nucleus and are more stable than heterogeneous nuclear RNA. The +30 and +1 RNAs are located primarily in the cytoplasm. The data support the notion that nucleotide sequences and/or secondary modifications in the 5' region determine if an RNA is to be transported.

Animals↗
PubMed1984

Cyclosporine-associated chronic nephropathy.

We evaluated glomerular filtration in 17 recipients of heart transplants who were treated for 12 months or longer with cyclosporine (cyclosporin A). The control group consisted of 15 heart-transplant recipients who were treated with azathioprine and who had also survived for at least 12 months. Despite an equivalent cardiac output, the glomerular filtration rate was depressed (51 +/- 4 vs. 93 +/- 3 ml per minute, P less than 0.005) in transplant recipients treated with cyclosporine. Cyclosporine treatment was also associated with reduced renal plasma flow (320 +/- 21 vs. 480 +/- 30 ml per minute, P less than 0.001). A trend toward restricted transglomerular transport of neutral dextrans (radii, 2.4 to 5.8 nm) in cyclosporine-treated recipients suggested an intrinsic loss of ultrafiltration capacity by glomerular capillaries rather than a hemodynamic basis for the reduced glomerular filtration rate. Histopathologic examination of the kidneys of five cyclosporine-treated patients with glomerular hypofiltration revealed a variable degree of tubulointerstitial injury accompanied by focal glomerular sclerosis. Among the 32 heart-transplant recipients treated for more than 12 months with cyclosporine at our center, end-stage renal failure developed in 2. We conclude that long-term cyclosporine therapy may lead to irreversible and potentially progressive nephropathy. We recommend that cyclosporine be used with restraint and caution until ways are found to mitigate its nephrotoxicity.

Adult↗
PubMed1984

Anuloaortic ectasia: a clinical and echocardiographic study.

Twenty-six patients with an aortic root diameter greater than or equal to 3.7 cm by 2-dimensional echocardiography (2-D echo) were studied. Group I consisted of 14 patients (mean age 50 +/- 14 years) with idiopathic anuloaortic ectasia and group II consisted of 12 patients (mean age 60 +/- 12 years) with secondary causes of aortic root dilatation. Patients in group I had a significantly larger aortic root diameter at the level of the aortic valve (5.0 +/- 0.7 cm) and 2 cm above the aortic valve (5.3 +/- 1.2 cm) as assessed by echo than did patients in group II (4.1 +/- 0.3 and 4.4 +/- 0.4 cm, respectively, p less than 0.025). The diameter of descending thoracic aorta was slightly larger in patients in group II (3.1 +/- 0.8 vs 2.7 +/- 0.5 cm, difference not significant). Over a mean follow-up period of 18 months, in group I, aortic dissection developed in 3 patients and severe aortic regurgitation and congestive heart failure in 2; 7 patients had aortic root grafting, aortic valve replacement or both. The 3 patients in group I with aortic dissection had an aortic root diameter greater than or equal to 5.3 cm, but 4 asymptomatic patients also had a diameter greater than 5 cm. Only 1 patient in group II required surgery for aortic dissection. Thus, 2-D echo is useful in identifying and following high-risk patients with anuloaortic ectasia.

Adult↗
PubMed1984

Studies on the polyglutamate specificity of methylenetetrahydrofolate dehydrogenase from pig liver.

Methylenetetrahydrofolate dehydrogenase, which is one of the activities of a trifunctional folate-dependent enzyme isolated from pig liver, displays an ordered bi-bi kinetic mechanism when methylenetetrahydropteroylmonoglutamate is used as the folate substrate [Cohen, L., & MacKenzie, R. E. (1978) Biochim. Biophys. Acta 522, 311-317]. We have studied the inhibition of this activity by a series of pteroylglutamates containing one to seven glutamyl residues. Inhibitors with one to four glutamyl residues exhibit a kinetically determined KD of about 56 microM for binding at the folate site of the enzyme, while inhibitors with five to seven glutamyl residues exhibit a KD of about 16 microM. These results suggest that folylpolyglutamates are bound to the trifunctional enzyme relatively weakly, with the major interaction involving the fifth glutamyl residue of the polyglutamate "tail". A free energy decrease of about 0.74 kcal (3.1 kJ) is associated with this interaction. The possibility of a swinging arm mechanism for the trifunctional enzyme is discussed. We have also measured the kinetic parameters Vmax and the Km values for NADP+ and the folate substrate associated with catalysis using a series of methylenetetrahydropteroylpolyglutamate substrates. The variation in these parameters with the length of the polyglutamate tail is small.

Animals↗
PubMed1984

Use of computerized tomography to assess myocardial infarct size and ventricular function in dogs during acute coronary occlusion and reperfusion.

Prospectively ECG-gated and nongated computed tomography (CT) can be used to assess global and regional left ventricular (LV) function and to measure myocardial infarct (MI) size. In the current study, CT was used to assess the effects of coronary occlusion and reperfusion in 16 dogs. Ten dogs were subjected to permanent occlusion of the proximal left anterior descending coronary artery and 6 dogs were reperfused after a 2-hour period of total coronary occlusion. Gated scans were used to quantitate the extent of wall thickening in the ischemic zone and to assess changes in mid-LV cross-sectional chamber area at end-diastole and end-systole. Nongated scans were used to estimate the size of the initial perfusion defect during contrast injection shortly after coronary occlusion and the size of the MI as indicated by delayed enhancement of the infarct 10 to 30 minutes after cessation of contrast administration. Neither group showed significant changes in end-diastolic chamber area during acute occlusion or 3 days later. Both groups showed a significant deterioration in percent change in chamber area both early after coronary occlusion and 3 days later; however, in the permanent occlusion group, percent wall thickening in the ischemic zone decreased from 46.2 +/- 16.5% (mean +/- standard deviation) to 1.6 +/- 9.0% during acute occlusion (p less than 0.01) and thickening remained depressed 3 days later (2.4 +/- 10.1%, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1984

Prediction of late mortality after myocardial infarction from variables measured at different times during hospitalization.

The long-term prognostic importance of sets of variables from different times in the hospital course after acute myocardial infarction was examined in 818 patients discharged from the hospital. Cardiac mortality during the first year after discharge was 11.1%. For the end point death within 1 year after admission, discriminant function analysis identified 5 important factors from the history and the first 24 hours of hospitalization: maximal level of blood urea nitrogen, previous myocardial infarction, age, displaced left ventricular apex (abnormal apex) on physical examination, and sinus bradycardia (negative correlation). When data from the entire hospitalization were included, extension of infarction and maximal heart rate were also selected. When variables obtained at discharge were included, only the presence of S3 gallop and abnormal apex were selected. In subgroups of patients, neither the left ventricular ejection fraction nor the presence of complex ventricular arrhythmias during a 24-hour ambulatory monitoring were independent predictors. Correct prediction was similar for each analysis, with 55 to 60% of the deaths and 79 to 81% of survivors correctly identified. The high-risk group consisted of 25% of the patients with 28 to 30% predictive value for death in the first year. In conclusion, outcome up to 1 year after acute myocardial infarction can be predicted early after admission. Addition of more information later during the hospitalization and at discharge did not improve correct prediction and may be redundant for prognostic evaluation.

Aged↗
PubMed1984

Right ventricular function in coronary artery disease as assessed by two-dimensional echocardiography.

Two-dimensional echocardiography (2DE) was performed in 64 patients with coronary artery disease. There were 46 men and 18 women, aged 58.7 +/- 11.4 years. An apical four-chamber view, a two-chamber right ventricular (RV) view, and a subcostal four-chamber view were obtained in 58 of 64 (91%) patients. Regional wall motion abnormalities ( RWMA ) of the RV free or diaphragmatic wall were detected in 4 of 18 (22%) patients with acute inferior myocardial infarction (IMI) and in 3 of 14 (21%) patients with old IMI. All seven patients with RWMA by 2DE had two or more of the following findings: hypotension, second- or third-degree atrioventricular block, atrial arrhythmias, or ventricular tachycardia. The RV ejection fraction by first-pass radionuclide angiography was 19.7 +/- 8.3% in patients with IMI and RV RWMA by 2DE compared to 35.3 +/- 9.6% (p less than 0.005) in patients without. A hyperdynamic RV wall motion was seen in 12 of 15 (80%) patients with acute anterior MI (AMI). No RV RWMA was observed in 17 patients with greater than 75% obstruction of right coronary artery and absent infarction. Thus, RWMA of the right ventricle were detected by 2DE in 22% of patients with IMI and identified patients with clinically significant RV dysfunction, probably due to RV infarction; a compensatory hyperdynamic RV wall motion was observed in 80% of patients with acute AMI.

Adult↗