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Biomedical subjects

J M Sullivan

Publications and source records attributed to J M Sullivan.

At least 73 records · Page 4Linked to original sources
PubMed1993

Left ventricular hypertrophy: effect on survival.

OBJECTIVES: The aim of the study was to determine whether left ventricular hypertrophy has an independent adverse effect on survival. BACKGROUND: Left ventricular hypertrophy is considered to be a significant risk factor for coronary heart disease mortality; however, the impact of coexisting coronary artery stenosis on survival statistics is not clear. METHODS: The relations among electrocardiographic (ECG) left ventricular hypertrophy, ST-T segment abnormality, coronary artery disease and survival were examined in 18,969 patients undergoing coronary arteriography between 1972 and 1985. Patients were excluded if they underwent coronary revascularization or had unstable angina, rheumatic or congenital heart disease, cardiomyopathy, pericardial disease or ECG changes other than left ventricular hypertrophy or repolarization abnormalities, leaving 4,824 patients for analysis. RESULTS: Left ventricular hypertrophy was present in 249 patients, whereas 4,575 were free of left ventricular hypertrophy. Five-year survival was 90.2% in the group without left ventricular hypertrophy and was significantly lower (81.9%, p < 0.001) in the group with left ventricular hypertrophy. Five-year survival was significantly lower in patients with left ventricular hypertrophy, regardless of whether coronary artery disease was present: 84.4% versus 94.5% (p = 0.016) in the absence of coronary artery disease and 81.0% versus 87.7% (p < 0.001) in the presence of coronary artery disease. The presence of ST segment abnormalities was not associated with a significant reduction in survival in patients without coronary disease, although mortality was less in those without ST changes who had coronary disease (p = 0.012). CONCLUSIONS: It is concluded that ECG left ventricular hypertrophy has an adverse effect on survival, even in patients who are free of coronary artery disease.

Adult↗
PubMed1993

Double-blind, placebo-controlled study of the efficacy of flosequinan in patients with chronic heart failure. Principal Investigators of the REFLECT Study.

OBJECTIVES: The aim of this study was to assess the efficacy of flosequinan in chronic heart failure. BACKGROUND: Flosequinan is a new vasodilator drug that acts by interfering with the inositol-triphosphate/protein kinase C pathway, an important mechanism of vasoconstriction. The drug dilates both peripheral arteries and veins, is orally active and has a long duration of action that permits once-daily dosing. Previous studies have shown that flosequinan produces sustained hemodynamic benefits in heart failure, but large scale studies evaluating its clinical efficacy have not been reported. METHODS: One hundred ninety-three patients with chronic heart failure (New York Heart Association functional class II or III and left ventricular ejection fraction < 40%) receiving digoxin and diuretic drugs were randomly assigned (double-blind) to the addition of flosequinan (100 mg once daily, n = 93) or placebo (n = 100) for 3 months. The clinical status and exercise tolerance of each patient was evaluated at the start of the study and every 2 to 4 weeks during the trial while background therapy remained constant. RESULTS: After 12 weeks, maximal treadmill exercise time increased by 96 s in the flosequinan group but by only 47 s in the placebo group (p = 0.022 for the difference between groups). Maximal oxygen consumption increased by 1.7 ml/kg per min in the flosequinan group (n = 17) but by only 0.6 ml/kg per min in the placebo group (n = 23), p = 0.05 between the groups. Symptomatically, 55% of patients receiving flosequinan but only 36% of patients receiving placebo benefited from treatment (p = 0.018). In addition, fewer patients treated with flosequinan had sufficiently severe worsening of heart failure to require a change in medication or withdrawal from the study (p = 0.07). By intention to treat, seven patients in the flosequinan group and two patients in the placebo group died. CONCLUSIONS: These findings indicate that flosequinan is an effective drug for patients with chronic heart failure who remain symptomatic despite treatment with digoxin and diuretic drugs. The effect of the drug on survival remains to be determined.

Chronic Disease↗
PubMed1993

Considerations for contraception in women with cardiovascular disorders.

Women with hypertension, angina pectoris, or mitral valve prolapse require special considerations when selecting an appropriate method of contraception. All three effective, reversible options (oral contraceptives, intrauterine devices, or progestin implants) carry some degree of added risk for these patient populations. However, pregnancy itself presents certain risks and, in the event of contraceptive failure, certain women with these disorders are at increased risk of developing serious cardiovascular sequelae that affect both mother and fetus. These negative effects can carry far into the neonatal period. This article describes the risk/benefit profiles of the currently available contraceptive options relative to their potential impact in these compromised women.

Cardiovascular Diseases↗
PubMed1993

Finite element computations of specific absorption rates in anatomically conforming full-body models for hyperthermia treatment analysis.

Finite element techniques for three-dimensional specific absorption rate (SAR) computation in anatomically based human models are presented. The formulations center on Helmholtz weak forms which have been shown to be numerically robust and to afford additional sparsity in the resulting system of algebraic equations. Practical solution of these equations depends critically on the realization of an effective sparse matrix solver. Experience with several conjugate gradient-type methods is reported. The findings show that convergence rate (and even convergence in some cases) degrades significantly with increasing matrix rank and decreasing electrical loss for mesh spacings which adequately resolve the physical wavelengths of the electromagnetic wave propagation. However, with proper choice of algorithm and preconditioning, reliable convergence has been achieved for matrix ranks exceeding 2 x 10(5) on domains having sizeable volumes of electrically lossless regions. An automatic grid generation scheme for constructing meshes which consist of variable element sizes that conform to a predefined set of boundaries is discussed. Example meshes of homogeneous and heterogeneous human anatomies, the boundaries of which have been derived from CT-scan information, are shown. These results highlight the fact that 3D finite element mesh generation remains a difficult problem, but usable meshes with this level of complexity can be generated. Integration of the finite element formulation, the sparse matrix solver, and the mesh generation scheme is shown to lead to algorithms that can be implemented on inexpensive reduced instruction set computer (RISC) workstations with run times on the order of hours. An example of hyperthermia device simulation is presented which suggests that the finite element method is a practical alternative that rivals the impressive finite-difference time-domain (FDTD) computations that have appeared.

Algorithms↗
PubMed1993

An opportunity for positive change. We have the history, experience, and will to preserve a Catholic presence in healthcare.

The charitable acts of women religious in response to the needs of the communities in which they settled is one of the great chapters in the history of the Church in America. But in the past two decades providers have had to contend with extraordinary changes in the healthcare environment. The Catholic healthcare mission was rooted in concern for the poor. Should Catholic healthcare providers withdraw from this field in which they have had such a significant presence and have contributed so much, or be driven from healthcare by the fiscal consequences of fidelity to mission? Instead, through its reform proposal, the Catholic Health Association has recommended that Catholic providers become advocates of change. However, even if change, such as universal access to healthcare, is achieved, we shall still have a society in which there will be many poor people. The challenge will be to see that healthcare for the poor does not become poor healthcare. Although the changing urban environment presents enormous challenges to providers, the Catholic healthcare ministry is a significant presence in urban areas. Widespread poverty accompanied by behavioral problems and social breakdowns are significant factors affecting healthcare and healthcare costs. Drug addiction; AIDS; teenage pregnancy; homelessness; the deterioration of the family; and generations of unemployment, anomie, abuse, and violence, which are often most acute in concentrated neighborhoods of poverty, challenge the ability of Catholic hospitals to meet their community's needs. Catholic providers today have a real opportunity to bring about positive changes in healthcare. They have the history, experience, and will to preserve a Catholic presence in the provision of healthcare.

Aged↗
PubMed1992

Human in situ dosimetry: differential insertion loss during passage through abdominal wall and myometrium.

We constructed a specialized in vivo exposimetry system and determined selected ultrasonic field quantities. We examined two groups of non-pregnant women (nulliparas = 14, multiparas = 9) under conditions of full and empty bladder. A calibrated 7-element linear array hydrophone was placed in the anterior fornix of the vagina in each subject. In the full bladder condition, the sound beam traversed the anterior abdominal wall and full bladder, whereas after voiding, the sound beam traversed the abdominal wall and anteverted uterine fundus. Each study was conducted using a 3.5 MHz mechanical sector transducer. Calibration data were recorded after completion of each in vivo experiment. Data from both groups were pooled for analysis. Assuming (1) the sound path through the full bladder is loss less, the insertion loss (ILFULL) should represent the insertion loss for the abdominal wall (ILABD WALL) 8.2 +/- 5.6 dB; whereas (2) for the empty bladder condition, (ILEMPTY) represents (ILABD WALL+ILUTERUS). Subtracting ILFULL from ILEMPTY yields ILUTERUS = 5.8 +/- 6.8 dB. Therefore, knowing the respective path lengths and normalizing for frequency, the mean tissue attenuation coefficients (A) are estimated to be AABD WALL = 1.39 dB/cm-MHz and AUTERUS = 0.14 dB/cm-MHz. These attenuation data suggest that the abdominal wall is the principal source of ultrasonic energy loss.

Abdominal Muscles↗
PubMed1992

Sustained and transient calcium currents in horizontal cells of the white bass retina.

Calcium currents were recorded from cultured horizontal cells (HCs) isolated from adult white bass retinas, using the whole-cell patch-clamp technique. Ca2+ currents were enhanced using 10 mM extracellular Ca2+, while Na+ and K+ currents were pharmacologically suppressed. Two components of the Ca2+ current, one transient, the other sustained, were found. The large transient component of the Ca2+ current, which has not been seen before in HCs, is similar, but not identical, to the T-type Ca2+ current described previously in a variety of preparations. The sustained component of the Ca2+ current is similar, but not identical, to the L-type current described in other preparations. FTX, a factor isolated from the venom of the funnel-web spider, Agelenopsis aperta, preferentially and irreversibly blocks the sustained component of the Ca2+ current at very dilute concentrations. The sustained component of the Ca2+ current inactivates slowly, over the course of 15-60 s, in some HCs. This inactivation of the sustained Ca2+ current, when present, is primarily voltage dependent rather than Ca2+ dependent.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1991

In situ exposimetry: the ovarian ultrasound examination.

We have constructed a specialized in vivo exposimetry system and developed and tested customized software using specially fabricated hydrophones. We placed the hydrophones in the lateral vaginal fornix as close to the ovary as possible (usually 1-2 cm from the ovary) and determined selected first-order and second-order ultrasonic field quantities during a routine ultrasound examination of the ovary. Our sonographic measurements yielded mean ultrasound beam path distances of 7.6 cm. (n = 18) in the presence of a distended bladder and 7.0 cm. (n = 25) in the presence of an empty bladder with an average group insertion loss of 6.2 dB and 7.3 dB, respectively. Using a Fixed Attenuation Model, the tissue attenuation coefficient value was 2.98 dB/MHz; whereas for the Overlying Tissue Model the value was 0.72 dB/cm-MHz. These data are both specific and unique in that they have been systematically obtained in situ.

Body Constitution↗
PubMed1991

Interactive effects of ST-T wave abnormalities on survival of patients with coronary artery disease.

Previous studies have documented a reduced survival time in patients with an electrocardiographic (ECG) ST-T wave abnormality. This study was designed to determine the clinical, hemodynamic and angiographic correlates of this observation. Data from 9,731 patients undergoing cardiac catheterization from 1976 through 1986 were analyzed; 5,531 had severe (greater than 70%) obstruction of at least one major coronary artery, 1,706 had mild (10 to 69%) obstruction and 2,494 had no obstruction. Of the patients with severe obstruction, 2,536 were treated medically and 2,995 were treated by surgical revascularization. Patients with an ST-T abnormality had more clinical risk factors (including older age and greater prevalence of diabetes mellitus, hypertension and prior myocardial infarction) and greater left ventricular dysfunction (including higher end-diastolic pressure and ventricular volume, reduced ejection fraction and greater prevalence of contraction abnormality) than did those without this ECG pattern. Survival time was significantly (p less than 0.01) reduced in subsets of patients with an ST-T abnormality and with severe or mild coronary artery disease; in those without coronary disease, ST-T changes did not correlate with reduced survival. Stepwise regression analysis was applied to each group to determine the independent predictors of 5-year survival. In patients with severe disease or no disease, an ST-T abnormality was not chosen as an independent predictor of 5-year survival; in the group with mild disease, ST-T changes were an independent predictor of reduced survival. Thus, the independent impact of an ST-T abnormality on survival is dependent on the severity of underlying coronary artery disease.

Cardiomegaly↗
PubMed1991

Salt sensitivity. Definition, conception, methodology, and long-term issues.

Several laboratories have examined the relation between salt intake and blood pressure in both experimental animals and humans. The human studies have used widely varying methodologies and different criteria for sodium sensitivity. Nonetheless, these studies have produced convincing data that the blood pressure of some individuals is far more sensitive to the effects of sodium depletion or loading than that of others. Furthermore, a minority of the population appears to comprise acutely salt-sensitive individuals. Some studies have shown that sodium-sensitive individuals share several characteristics. They include increased forearm vascular resistance, decreased venous compliance, suppressed plasma renin activity, and lower circulating aldosterone concentration. These findings have also been described in the Dahl salt-sensitive rat, which suggest a genetic link in humans as well as the rat. Long-term follow-up of sodium-sensitive and sodium-resistant groups has shown that although blood pressure levels are approximately equal in the two groups during sodium depletion, resumption of a daily sodium intake of about 150 meq results in significantly higher levels of blood pressure and forearm vascular resistance in the sodium-sensitive group. This difference persists for at least 12 months.

Animals↗
PubMed1991

Copper toxicosis in veal calves.

Copper toxicosis was diagnosed in 7 veal calves, 10-16 weeks old, from 5 separate farms. All calves died without specific clinical signs, although 4 of the calves were icteric. The calves' dietary rations had been supplemented with various copper-containing hematinics. Peritoneal hemorrhage was reported at post-mortem in 2 calves. Microscopic evidence of hepatopathy consisted of hepatocellular degeneration and necrosis, hemorrhage, and fibrosis. Concentrations of copper in livers from intoxicated calves ranged from 277 to 684 ppm and in kidneys from 1.1 to 82.0 ppm. The extent and severity of lesions in livers appeared to correlate with concentrations of copper. Nephrosis was minimal, without evidence of hemoglobinuria.

Animals↗