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Biomedical subjects

A Porter

Publications and source records attributed to A Porter.

At least 37 records · Page 2Linked to original sources
PubMed2000

Effects of soil and water content on methyl bromide oxidation by the ammonia-oxidizing bacterium Nitrosomonas europaea.

Little information exists on the potential of NH(3)-oxidizing bacteria to cooxidize halogenated hydrocarbons in soil. A study was conducted to examine the cooxidation of methyl bromide (MeBr) by an NH(3)-oxidizing bacterium, Nitrosomonas europaea, under soil conditions. Soil and its water content modified the availability of NH(4)(+) and MeBr and influenced the relative rates of substrate (NH(3)) and cosubstrate (MeBr) oxidations. These observations highlight the complexity associated with characterizing soil cooxidative activities when soil and water interact to differentially affect substrate and cosubstrate availabilities.

Ammonia↗
PubMed2000

Correlation of predischarge electrocardiographic patterns with left ventricular function in patients with anterior wall myocardial infarction.

The aim of this prospective study was to assess the correlation between different predischarge electrocardiographic patterns and left ventricular function, evaluated by physical examination and echocardiography, in patients with first Q wave anterior acute myocardial infarction. A positive correlation was found between the electrocardiographic pattern and wall motion score assessed by echocardiography, reflecting a gradual worsening in left ventricular function among the different patterns. Patients with an isoelectric ST segment and negative T waves had a 73% decrease in the risk of clinical heart failure compared to those who continued to have ST elevation. Thus, a predischarge electrocardiogram can be used as a simple, noninvasive method for the risk stratification of patients with acute myocardial infarction.

Adult↗
PubMed2000

Correlation between the admission electrocardiogram and regional wall motion abnormalities as detected by echocardiography in anterior acute myocardial infarction.

We correlated ST elevation in various leads on admission and regional dysfunction in 132 patient with first anterior acute myocardial infarction using echocardiography. ST elevation in leads I and a VL and II, III and aVF was not associated with a specific pattern of regional dysfunction. Basal anterior and septal regional dysfunction were seen more often in patients with ST elevation in V1 (49 vs. 25%, p = 0.006; 35 vs. 17%, p = 0.048, respectively). Patients with ST elevation in V2 had more regional dysfunction of the apical inferior region (84 vs. 53%; p = 0.01). ST elevation in V5 and V6 was not associated with more apical or lateral wall motion abnormalities. ST elevation in lead V1 in anterior myocardial infarction is associated with a high incidence of regional dysfunction of the basal anterior, anteroseptal and septal regions.

Aged↗
PubMed1999

Combined low-dose-rate brachytherapy and external beam radiation for cervical cancer: experience over ten years.

Cervical cancer was treated with a combination of external beam and intracavitary radiation during a 10-year period at Wayne State University. Data were collected for 216 patients treated radically with external beam radiation (EBRT) and low-dose-rate brachytherapy for cervical cancer between 1980 and 1991 at Wayne State University. Patient distribution by stage was IB, 20.8%; IIA, 7.4%; IIB, 26.9%; IIIA, 1.8%; IIIB, 40.7%; and IVA, 2.3 %. Survival curves were constructed using Kaplan-Meier methods and differences between groups were tested for significance using the log-rank test. Multivariate analysis was done using the Cox proportional hazards model. With a median follow-up of 114 months, actuarial disease-free survival for all patients was 60% at 5 years and 55% at 10 years. Actuarial 5-year survival for Stage IB was 79%; for Stage II, 59%; and for Stage III, 53%. There were 14/216 (6%) of patients with severe late complications. On univariate analysis, race was found to be statistically significant, with Caucasian patients having better survival than African American (P = 0.03). The survival for patients treated in shorter overall times was significantly higher (P<0.001), especially with treatment completion in under 58 days. The stepwise Cox multivariate analysis provided the following significant results: race (African American vs. Caucasian; P = 0.04, RR = 1.6), Stage (II vs. I, P = 0.004, RR = 2.6), Stage (III vs. I; P = 0.004, RR = 2.5), and overall treatment time (P = 0.006, RR = 1.62). Rates of local control, survival, and complications among women treated with combined external beam and intracavitary radiation for cervix cancer were similar to those of prior retrospective studies.

Actuarial Analysis↗
PubMed1999

Acute myocardial infarction following sildenafil citrate (Viagra) intake in a nitrate-free patient.

Since its introduction to the market in March 1997, sildenafil acetate (Viagra) has been prescribed to 1.7 million people. Sixteen men who were taking the drug have died, 7 of them during or soon after sexual activity. Most of these data have been derived from the media and not from the scientific literature. There is a general impression that cardiovascular complications of sildenafil occur mainly when the drug is taken concomitantly with nitrates. We describe a 65-year-old man with known coronary artery disease who had an acute myocardial infarction shortly after taking sildenafil and engaging an sexual activity. The patient had not been using nitrates. We suggest that the emotional arousal induced by Viagra, followed by the heavy physical exertion during sexual activity, triggers plaque rupture that leads to acute myocardial infarction.

Aged↗
PubMed1999

The natural history of aortic valve disease after mitral valve surgery.

OBJECTIVES: The present study evaluates the long-term course of aortic valve disease and the need for aortic valve surgery in patients with rheumatic mitral valve disease who underwent mitral valve surgery. BACKGROUND: Little is known about the natural history of aortic valve disease in patients undergoing mitral valve surgery for rheumatic mitral valve disease. In addition there is no firm policy regarding the appropriate treatment of mild aortic valve disease while replacing the mitral valve. METHODS: One-hundred thirty-one patients (44 male, 87 female; mean age 61+/-13 yr, range 35 to 89) were followed after mitral valve surgery for a mean period of 13+/-7 years. All patients had rheumatic heart disease. Aortic valve function was assessed preoperatively by cardiac catheterization and during follow-up by transthoracic echocardiography. RESULTS: At the time of mitral valve surgery, 59 patients (45%) had mild aortic valve disease: 7 (5%) aortic stenosis (AS), 58 (44%) aortic regurgitation (AR). At the end of follow-up, 96 patients (73%) had aortic valve disease: 33 AS (mild or moderate except in two cases) and 90 AR (mild or moderate except in one case). Among patients without aortic valve disease at the time of the mitral valve surgery, only three patients developed significant aortic valve disease after 25 years of follow-up procedures. Disease progression was noted in three of the seven patients with AS (2 to severe) and in six of the fifty eight with AR (1 to severe). Fifty two (90%) with mild AR remained stable after a mean follow-up period of 16 years. In only three patients (2%) the aortic valve disease progressed significantly after 9, 17 and 22 years. In only six patients of the entire cohort (5%), aortic valve replacement was needed after a mean period of 21 years (range 15 to 33). In four of them the primary indication for the second surgery was dysfunction of the prosthetic mitral valve. CONCLUSIONS: Our findings indicate that, among patients with rheumatic heart disease, a considerable number of patients have mild aortic valve disease at the time of mitral valve surgery. Yet most do not progress to severe disease, and aortic valve replacement is rarely needed after a long follow-up period. Thus, prophylactic valve replacement is not indicated in these cases.

Adolescent↗
PubMed1999

Sign-language interpretation in psychotherapy with deaf patients.

Sporadic encounters with deaf patients seeking psychotherapy present a challenge to general clinicians outside of specialized services for the deaf. Skills for working with people who do not share one's own language mode and culture are not routinely taught in most training programs, so clinicians may be unprepared when they first encounter a deaf patient. While it would be ideal to be able to match deaf patients with therapists fluent in their preferred language mode, this is often not feasible in smaller centers. Working with a trained professional sign-language interpreter can be a productive alternative, as long as patient, therapist, and interpreter understand and are comfortable with the process. Peer-reviewed literature on sign language interpretation in psychotherapy is sparse, but some practical guidelines can be gleaned from it and supplemented by information provided by the deaf community through the Internet. This paper arose from one psychiatric resident's first experience of psychotherapy working with a sign-language interpreter, and summarizes the literature search that resulted from a quest for understanding of deaf culture and experience, of the unique characteristics of sign language, and of the effects on the therapeutic relationship of the presence of the interpreter.

Adult↗
PubMed1999

The parturition defect in steroid 5alpha-reductase type 1 knockout mice is due to impaired cervical ripening.

Successful delivery of the fetus (parturition) depends on coordinate interactions between the uterus and cervix. A majority (70%) of mice deficient in the type 1 isozyme of steroid 5alpha-reductase fail to deliver their young at term and thus manifest a parturition defect. Using in vitro and in vivo measurements we show here that rhythmic contractions of the uterus occur normally in these mutant mice at the end of gestation. In contrast, the cervix of the mutant animal fails to ripen at term as judged by biomechanical, histological, and endocrinological assays. Impaired metabolism of progesterone in the cervix of the mutant mice in late gestation leads to an accumulation of this steroid in the tissue. We conclude that a failure of cervical ripening underlies the parturition defect in mice lacking steroid 5alpha-reductase type 1 and that this enzyme normally plays an essential role in cervical progesterone catabolism at the end of pregnancy.

20-alpha-Dihydroprogesterone↗
PubMed1999

Tricuspid regurgitation late after mitral valve replacement: clinical and echocardiographic evaluation.

BACKGROUND AND AIM OF THE STUDY: Significant tricuspid regurgitation (TR) can contribute to increased morbidity and mortality in patients after mitral valve replacement (MVR), both in the immediate and late postoperative period. The aim of this study was to evaluate the prevalence and the clinical importance of TR late after MVR, as assessed both clinically and echocardiographically. METHODS: The study group comprised 65 patients (39 women, 26 men; mean age 61+/-12 years) with rheumatic heart disease who had undergone MVR without tricuspid valve surgery between one and 30 years (mean 11.3+/-8 years) before their last clinical examination. All patients underwent a complete color-Doppler echocardiographic examination. The predominant presurgical mitral lesion was stenosis in 44 patients and regurgitation in 21. The severity of the tricuspid valve disease was assessed echocardiographically using color-Doppler flow images and flow direction in the inferior vena cava or hepatic veins, and by clinical evaluation. RESULTS: Echocardiography revealed significant late TR in 44 patients (67%), which was moderate in 16 and severe in 28, and evident on physical examination in 24 cases (37%). Age (relative risk (RR) = 1.1; C.I. 1-1.1) and female sex (RR = 1.8; C.I. = 1.0-3.2) were identified as statistically significant predictors for late clinical TR development, but only age was found as a statistically significant predictor for echocardiographic TR development. An elevated RR for organic TR and predominant mitral regurgitation was found. In contrast, pre- and postoperative pulmonary artery pressure, predominant mitral lesion, prosthetic valve gradient and regurgitation were similar in patients with and without late TR. CONCLUSIONS: Significant TR diagnosed by echocardiography late after MVR is common, and clinically evident in more than one-third of patients. Therefore, a lower threshold for tricuspid valve repair should be considered when mitral valve surgery is carried out.

Aged↗
PubMed1998

Mitral annular calcium detected by transthoracic echocardiography is a marker for high prevalence and severity of coronary artery disease in patients undergoing coronary angiography.

This study tests the hypothesis that mitral annular calcium (MAC) detected by transthoracic echocardiography (TTE) is a marker for high prevalence and severity of coronary artery disease (CAD) in patients undergoing coronary angiography. Pathological studies have suggested that there is an association between MAC and calcific deposits in coronary arteries; however, there are no clinical data to support this association. One hundred sixty-five patients with MAC (101 women and 64 men; mean age 71 +/- 8 years) who underwent cardiac catheterization with coronary angiography for various reasons were compared with 147 age-matched controls without MAC who underwent coronary angiography for the same indications during the same period. MAC was defined as a dense, localized, highly reflective area at the base of the posterior mitral leaflet detected by TTE. Obstructive CAD was defined as either > or = 50% reduction of the internal diameter of the left main coronary artery or > or = 70% reduction of the internal diameter of the left anterior descending, right coronary, or left circumflex artery distribution. Compared with controls, the MAC group had a significantly higher prevalence of CAD (89% vs 75%, p = 0.001) and higher rates of 3-vessel disease (45% vs 24%, p = 0.001) and left main CAD (13% vs 5%, p = 0.009). Nonsignificant CAD was more common in the control group (25% vs 11%, p = 0.001). Multivariate analysis identified MAC (p = 0.0002), indications for cardiac angiography (p = 0.02), sex (p = 0.03), and diabetes mellitus (p = 0.03) as independent predictors for the presence and severity of obstructive CAD. MAC detected by TTE may be a marker for high prevalence and severity of CAD in patients undergoing coronary angiography.

Adult↗
PubMed1998

Prostate-specific antigen levels are higher in African-American than in white patients in a multicenter registration study: results of RTOG 94-12.

PURPOSE: To compare serum prostate-specific antigen (PSA) levels in a national sample of African-American and white men with prostate cancer, and to attempt to explain any differences by using self-reported individual-level socioeconomic status adjustments. METHODS AND MATERIALS: During 4 1/2 months in 1994-95, 709 patients with nonmetastatic prostate cancer were enrolled in this prospective study; 17.5% were African-American and 82.5% were white. Information about clinical stage, tumor grade, pretreatment PSA, type of insurance, and educational and income status was obtained. Serum PSA levels were measured and racial differences were found; how the differences were influenced by other patient- or tumor-related factors and if the differences could be explained by socioeconomic status disparities were determined. In univariate analyses, factors associated with the mean PSA levels were studied; log-converted values were used to yield a normal distribution. Multivariate analyses were done on log-linear models for description of association patterns among various categorical variables; a perfectly fitted model should have a correlation value (CV) of 1.0. RESULTS: The mean PSA level was higher in African-Americans (14.68 ng/ml) than in whites (9.82 ng/ml) (p = 0.001). Clinical stage (p = 0.001), Gleason sum tumor grade (p = 0.0001), educational level (p = 0.001), and household income (p = 0.03) were also associated with mean PSA levels; age, type of biopsy, and insurance status were not. Disease stage (p = 0.0001), grade (p = 0.0001), education (p = 0.07), and income (p = 0.02) were all associated with PSA levels for whites, but none of these factors were important for African-Americans (all p values > 0.1). The best fitted log-linear model (CV = 0.99) contained PSA (< 10, 10-20, and > 20), Gleason sum grade (2-5, 6-7, and 8-10), race, and two interactions: PSA by race (p = 0.0012) and PSA by Gleason sum (p = 0.0001). Models replacing race for either income (CV = 0.82) or education (CV = 0.82) or both (CV = 0.78) did not fit as well. CONCLUSIONS: African-Americans with nonmetastatic prostate cancer have higher serum PSA levels at diagnosis than whites, implying a higher tumor cell burden. Individual-level household income, education, or insurance status alone or in combination account for racial differences, but only partially.

Analysis of Variance↗