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Biomedical subjects

J A Alexander

Publications and source records attributed to J A Alexander.

At least 19 recordsLinked to original sources
PubMed1992

Use of transesophageal echocardiography to visualize an anomalous right coronary artery arising from the left main coronary artery (single coronary artery).

This case report demonstrates a role for transesophageal echocardiography in defining the course of anomalous coronary arteries. Origin of the right coronary artery (RCA) from the left main (LM) (single coronary artery) is an exceedingly rare congenital anomaly. It is not always benign and may result in myocardial infarction. This may be due to compression between the aorta and the pulmonary artery. Transesophageal echocardiography offers a low-risk, noninvasive means of imaging the proximal coronary arteries. In the majority of patients, the proximal segments of the three major coronaries can be clearly visualized. With the addition of color flow, it is possible to visualize flow in most patients. Proximal obstructive lesions can be seen in some patients although sensitivity thus far seems low.

Blood Flow Velocity↗
PubMed1992

Familial cardiac myxoma.

The majority of cardiac myxomas occur sporadically as isolated lesions in the left atrium of middle-aged women. However, a "familial" form and a "syndrome" form of this lesion have been identified. The syndrome myxoma can present with pigmented skin lesions and peripheral or endocrine neoplasms. The familial and syndrome forms of cardiac myxomas can usually be distinguished from the sporadic form by the presentation at a younger age, the unusual location and multicentricity of the lesions, and the presence of rare pathological conditions. In addition, a higher rate of recurrent lesions is usually associated with the familial and syndrome forms of this disease. To date, 15 families with cardiac myxomas have been reported in the world's literature. Here we present 2 additional case reports.

Adolescent↗
PubMed1992

The effect of the social organization of work on the voluntary turnover rate of hospital nurses in the United States.

In light of current concerns over nursing shortages and productivity, voluntary turnover among hospital nurses in the United States has assumed renewed importance as a managerial issue. This study examines the thesis that the social organization of work in hospitals is an important determinant of the voluntary turnover rate among registered nurses. This perspective differs from previous work in this area in that both turnover and its determinants are conceptualized at the organizational rather than individual level, thus opening the way for administrative intervention to reduce turnover. The conceptual model is tested using multiple regression techniques on a sample of 435 hospitals. Results suggest that organizational characteristics and environmental conditions are important contributors to turnover. Organizational characteristics are stronger predictors of turnover than are economic factors.

Career Mobility↗
PubMed1992

Oxygen saturation and breathing patterns in preterm infants with cyanotic episodes.

The pathophysiology of cyanotic/apnoeic episodes in preterm infants was investigated using overnight tape recordings of beat-to-beat arterial oxygen saturation (SaO2), plethysmographic waveforms from the oximeter, breathing movements and nasal airflow. Recordings were made in 16 preterm infants with recurrent cyanotic episodes of unknown cause that had received stimulation or resuscitation, and 15 preterm controls, matched for birth weight, post-conceptional and postnatal age. The recordings were analysed for baseline SaO2, the number of hypoxaemic episodes (SaO2 < or = 80% for > or = 4 s) and the breathing patterns associated with each episode. There was a significant difference in the total number of hypoxaemic episodes between patients and controls (520 versus 100; p < 0.01), but no difference was found for mean baseline SaO2 (98.6 versus 99.0%; p > 0.05). The mean duration of each hypoxaemic episode in the patients was 9.5 s compared with 5.8 s in the controls (p < 0.01). Although most hypoxaemic episodes (62 and 76%) were associated with pauses in breathing movements, a proportion (8 and 18%, respectively) occurred despite continuous airflow and breathing movements in both patients (6 of 16) and preterm controls (2 of 15). The rate of decrease in SaO2 was significantly more rapid during these latter hypoxaemic episodes than during episodes associated with isolated apnoeic pauses (8.5 versus 3.2% per second, p = 0.02). Preterm infants with cyanotic episodes have increased numbers of clinically unapparent hypoxaemic episodes, some of which have continued ventilation and rapid desaturation. The pathogenesis of these episodes warrants further investigation.

Birth Weight↗
PubMed1992

Patient memory before and after cardiac operations.

The memories of 20 patients undergoing elective operations on the heart were assessed by a comprehensive battery of standardized psychometric tests. Testing was conducted 1 to 2 days before, 7 to 10 days after, and 1 month after each operation. Twenty age-matched, healthy control subjects were given the same battery of tests at comparable times. Compared with healthy subjects, the patient group had significantly lower scores on 3 of 19 tests before, 10 of 19 tests 1 week after, and 5 of 19 tests 1 month after surgical intervention. The patient group had similar test performances before and 1 week after the operations and improved on 3 of 19 measures 1 month after the operations. Degrees of illness and cardiopulmonary bypass variables were significantly related to only a small subset of memory measures. Results of this study are consistent with previous reports that underscore the contribution of nonspecific aspects of surgical intervention to neuropsychologic dysfunction in the immediate postoperative period. We conclude that neither the illness nor the surgical variables are directly related to substantial variance in cognitive function after operations on the heart.

Adult↗
PubMed1991

Identification of 7-(2-hydroxyethyl)guanine as a product of alkylation of calf thymus DNA with clomesone.

Evidence at the molecular level is presented in support of alkylation of O6-guanine moieties of DNA as the mechanism of cytotoxicity of Clomesone to HT-29 cells and consists in the isolation and identification of a product resulting from alkylation of calf thymus DNA with Clomesone, followed by depurination to yield 7-(2-hydroxyethyl)guanine, whose formation is reasonably explained by O6-guanine chloroethylation followed by intramolecular alkylation at N7 of guanine and subsequent hydrolysis to the hydroxyethylguanine.

Alkylation↗
PubMed1991

Familial recurring cardiac myxoma.

A 34-year-old woman presented with her fourth occurrence of an atrial myxoma and a right lower lung field mass. Her surgical history was extensive. In addition to resection of three previous atrial myxomas, she had undergone resection of her adrenal glands as a teenager because of Cushing's syndrome, and a hysterectomy at age 26 revealed a myxoid leiomyoma. Family history was remarkable as a maternal uncle and daughter died from embolic complications of left atrial myxomas and her sister previously had a left atrial myxoma resected. The patient underwent uncomplicated removal of the myxoma, and resection of the lung mass revealed a granuloma. A review of typical and atypical aspects of cardiac myxomas is provided including a rare and recently described syndrome of familial cardiac myxoma associated with Cushing's syndrome, spotty skin pigmentation and other myxoid tumors.

Adult↗
PubMed1991

Acute porphyria presenting with hyperamylasemia.

An elevation of serum amylase and lipase has not been reported previously to occur with porphyria. In this report, we describe a patient who presented with the clinical and laboratory picture of pancreatitis: elevated amylase, lipase, amylase-creatinine clearance ratio, and with abdominal pain. Only after extensive evaluation, was the patient found to have porphyria. On two separate occasions, with hematin therapy, her serum amylase decreased, as did her clinical symptoms of porphyria and her urinary quantitative porphyrins. This suggests an association between elevation of the serum amylase and lipase with acute porphyria. Moreover, this association can lead to delay in establishing the diagnosis of acute porphyria.

Acute Disease↗
PubMed1991

Radiation-associated valvular disease.

The prevalence of radiation-associated cardiac disease is increasing due to prolonged survival following mediastinal irradiation. Side effects of radiation include pericarditis, accelerated coronary artery disease, myocardial fibrosis and valvular injury. We evaluated the cases of three young patients with evidence of significant valvular disease following mediastinal irradiation. One patient underwent the first reported successful aortic and mitral valve replacement for radiation-associated valvular disease (RAVD) as well as concurrent coronary artery revascularization. A review of the literature revealed 35 reported cases of RAVD, with only one successful case of valve replacement that was limited to the aortic valve. Asymptomatic RAVD is diagnosed 11.5 years after mediastinal irradiation compared with 16.5 years for symptomatic patients, emphasizing that long-term follow-up is important for patients receiving mediastinal irradiation. This study defines a continuum of valvular disease following radiation that begins with mild asymptomatic valvular thickening and progresses to severe valvular fibrosis with hemodynamic compromise requiring surgical intervention.

Adolescent↗
PubMed1991

The Blalock-Taussig shunt in the newborn infant.

Children with pulmonary oligemia often require palliation in the newborn period. The Blalock-Taussig shunt has been shown to offer adequate palliation in the older child, but its use in the newborn period remains controversial. A retrospective review of 51 neonates younger than age 2 weeks undergoing a Blalock-Taussig shunt (or modification) was performed. The operative mortality rate was 5.8%. Six children (15.4%) required reoperation in the first year of life for inadequate shunt function. The modification with interposition grafts necessitated reoperation more often than shunts performed with the subclavian artery.

Anastomosis, Surgical↗
PubMed1991

Magnetic resonance findings in a patient with internuclear ophthalmoplegia. Neuroradiological-clinical correlation.

A 49-year-old female presented with symptoms compatible with internuclear ophthalmoplegia. Magnetic resonance using T2-weighted images showed an eccentric area of high signal intensity in the mid pons corresponding to the right medial longitudinal fasciculus. Magnetic resonance is the method of choice when internuclear ophthalmoplegia is suspected. The findings should be differentiated from the normal central hyperintensity called the "pseudo MLF hyperintensity."

Female↗
PubMed1990

Gastrointestinal tract hemorrhage. The value of a nasogastric aspirate.

A bloody nasogastric aspirate is believed to imply active upper gastrointestinal tract bleeding, while a nonbloody yellow-green nasogastric aspirate that contains duodenal secretions suggests the absence of bleeding proximal to the ligament of Treitz. To validate these beliefs, physicians were asked to predict the presence of active gastrointestinal tract bleeding and whether bile was present in a nasogastric aspirate obtained immediately before endoscopy in 73 episodes of bleeding in 62 patients. A relationship was found between the physician's assessment of the presence of active bleeding demonstrated endoscopically and the appearance of the nasogastric aspirate. However, the sensitivity and specificity were low (79% and 55%, respectively). No association between the assessment of bile in the nasogastric aspirate and the presence of bile acids was demonstrated. These data do not support the placement of a nasogastric tube to determine whether or not a patient is bleeding, the location of the bleeding, and whether endoscopy should be performed.

Bile↗
PubMed1990

Serum-ascites albumin gradients in nonalcoholic liver disease.

Several studies performed in alcoholics with advanced liver disease have demonstrated a positive correlation between the serum-ascites albumin gradient (SAAG) and measured portal venous pressure. A single study performed in 15 patients with exudative malignant ascites and 29 patients with alcoholic liver disease demonstrated that a SAAG of less than 1.1 was essentially diagnostic of a malignant origin of the ascites. In an effort to confirm and extend these observations to individuals with nonalcoholic liver disease, 24 patients with nonalcoholic liver disease and 11 with alcoholic liver disease undergoing orthotopic liver transplantation (OTLx) were studied. At the time of liver transplantation, each had their serum and ascitic fluid albumin levels determined, the gradient calculated, and their portal venous pressure (PVP) as well as the corrected portal venous pressure (PPc) measured directly. A significant correlation (r = 0.624) between the PPc and the SAAG was found in the 11 alcoholics (P less than 0.05). No such correlation existed for those with nonalcoholic liver disease (r = 0.398). Moreover, a SAAG less than 1.1 was found in three of nonalcoholics with cirrhosis in the absence of an abdominal malignancy. We conclude that (1) the SAAG and PPc are statistically related to each other in individuals with alcoholic liver disease but not in those with a nonalcoholic cause for cirrhosis, and (2) SAAG less than 1.1 is not diagnostic of abdominal malignancy but can occur in those with advanced nonmalignant hepatic disease.

Adult↗
PubMed1990

Feasibility of reversible pulmonary artery banding: early results and intermediate-term follow-up.

Development of a reversible pulmonary artery band might obviate the need for a second cardiac surgical procedure in children with some forms of congenital heart disease. We evaluated a segmented Silastic-coated Dacron mesh band 2 to 4 mm wide sewn together with absorbable 2-0 polydioxanone suture for use as a reversible pulmonary artery band. Nine puppies 6 to 8 weeks old (mean weight, 5.8 kg) underwent placement of this pulmonary artery band. All survived the operation with a mean initial systolic gradient of 6.5 +/- 1.6 mm Hg and underwent cardiac catheterization at monthly intervals for 3 months. Two puppies died of right ventricular failure. The remaining puppies underwent balloon angioplasty with balloons 20 to 25 mm in diameter. No complications resulted from balloon angioplasty, but 1 puppy died 24 hours later of unidentified causes. Balloon angioplasty decreased the mean gradient from 46.7 +/- 6.8 mm Hg to 6.7 +/- 2.6 mm Hg. Angiography showed an increase in mean diameter of the site of the pulmonary artery band from 5.2 +/- 1.0 to 10.8 +/- 1.7 mm Hg. There was no evidence of vessel injury on angiograms. Fourteen months after balloon angioplasty, the mean gradient was 22.3 +/- 17.0 mm Hg. Our data demonstrate that a functionally reversible pulmonary artery band constructed of segmented Silastic-coated Dacron mesh and 2-0 polydioxanone suture is feasible.

Angioplasty, Balloon↗
PubMed1990

Physician integration strategies and hospital output. A comparison of rural and urban institutions.

Physician integration strategies are attempts to bring physicians into hospital administration by giving them a role on the hospital board, employing them in administrative or clinical capacities, or expanding the administration issues dealt with by medical staff committees. This study used a production function model to examine whether such strategies affect hospital output, measured as case mix-adjusted discharges. The article hypothesizes that less management depth, smaller medical staffs, and an absence of nearby hospitals make physician integration a more important strategy for rural than urban hospitals. American Hospital Association data on 1,309 hospitals from 1982 showed there is no statistically significant evidence that physician integration affects the output of urban hospitals. However, four of the five measures were associated with more patient discharges in rural hospitals. Furthermore, rural and urban hospitals differ in their use of other inputs. It was concluded that physician integration can be an effective mechanism to enhance rural hospital output and that more research on rural hospitals is needed.

Decision Making↗