Biomedical subjects
Publications and source records attributed to S A Friedman.
An asymptomatic woman was evaluated because of a chest x-ray examination suggesting an aortic aneurysm. CT scan revealed proximal aortic dissection, which had apparently leaked into the pericardium. Increased use of CT scanning is expanding our knowledge of the clinical spectrum of aortic dissection.
The etiology of preeclampsia remains unknown. Because of their widespread and varied effects in the human body, prostaglandins--specifically PGI2, thromboxane A2, PGE, and PGF2 alpha--have come under much investigation as possible etiologic factors. The vasodilating, platelet-disaggregating prostaglandins (PGI2 and PGE) are increased during normal pregnancy and may account for many of the observed hemodynamic changes, which begin as early as the first trimester. In contrast, a relative increase in the vasoconstricting, platelet-aggregating prostaglandins (thromboxane A2 and PGF2 alpha) is seen in preeclampsia. The disruption in the delicate balance between these two opposing pairs of prostaglandins may play an important role in the causation of preeclampsia. The growing body of literature that deals with the relationship between prostaglandins and preeclampsia is discussed.
We have defined a minimal partition site, parS, from the plasmid P1. It contains sufficient cis-acting information to direct accurate segregation of low-copy-number plasmids that contain it as long as the two essential P1 Par proteins are supplied in trans. The site is, at most, 34 base pairs and contains a perfect 13-base-pair inverted repeat. Site-directed mutations were made within the repeat sequence that abolished activity whether or not the symmetry of the palindrome was maintained. Partition appears to be a competitive process, as differentially marked plasmids carrying the same type of partition site are not independently segregated but are randomly distributed with respect to each other. We have studied competition between plasmids carrying various fragments encompassing the parS site. As expected, two plasmids carrying the minimal parS site compete with each other. However, a sequence that lies to the left of the minimal parS site acts as a major modulator of this competition, changing the specificity of the competitive effect completely. Thus, this adjacent sequence appears to be an important determinant of the specificity of the wild-type P1 partition system without being necessary for its efficient function.
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A 56-year-old woman with no history of cardiac disease developed acute pulmonary edema following a subarachnoid hemorrhage. A constellation of findings, including elevated creatine kinase MB isoenzyme activity in the absence of electrocardiographic or scintigraphic evidence of acute myocardial infarction, elevated pulmonary artery wedge pressure, segmental wall motion abnormalities, and depressed ejection fraction of the left ventricle demonstrated by two-dimensional echocardiography and radionuclear ventriculography, pointed to a direct myocardial injury leading to cardiac failure. The evidence for cardiogenic origin of pulmonary edema provided by this case is in contrast to the belief that "neurogenic" pulmonary edema is of noncardiac origin.
Prior to the advent of two-dimensional echocardiography, atrial septal aneurysm was rarely diagnosed during life. In this article, two-dimensional echocardiography identified an atrial septal aneurysm as the site of intracardiac right-to-left shunting, causing hypoxemia in a patient with acute right ventricular infarction. In addition to this rare presentation, the patient also had systemic embolism, a known complication of atrial septal aneurysms.
The gam locus of bacteriophage lambda encompasses two coding sequences with the same reading frame and translational stop, one corresponding to an Mr 11646 polypeptide (gamS gene), the other to an Mr 16349 polypeptide (gamL gene). A DNA segment encoding gamS but not gamL was placed under lambda pR promoter control (regulated by the cIts857-coded repressor) on a multicopy plasmid, and an insertion mutation (gamS201) was constructed. Expression of gamS+, but not gamS201, inhibited Escherichia coli RecBC nuclease in vivo; the criteria were inhibition of chromosomal DNA degradation after UV irradiation and plating of T4 gene 2- phages. The recB+ C+ bacteria expressing gamS+ were completely or partially similar to recC- mutants with respect to certain phenotypes: defective plating of phages P1 and P2, ability to plate (in a recA- background) lambda red- gam- phages, reduced resistance to UV irradiation, defective SOS induction, decreased colony-forming ability.
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In 20 elderly patients (mean age, 76 years; range, 70 to 86 years), hypertrophic cardiomyopathy was diagnosed echocardiographically. Although the disease was moderate to severe in all patients, the diagnosis was not suspected in 19 patients prior to echocardiography. Inappropriate therapy consisting of potentially harmful drugs, such as digitalis, nitrates, and diuretics, was commonly used, often for unclear indications. Since echocardiography can easily and accurately diagnose hypertrophic cardiomyopathy, an increased awareness of its occurrence in the elderly and use of echocardiography would reduce diagnostic and therapeutic errors.
The boundaries of the P1 par (plasmid partition) region of the unit-copy plasmid P1 were defined to within 2.7 X 10(3) base-pairs of DNA. The DNA sequence of the region revealed two large open reading frames that could encode proteins of Mr 44,000 and Mr 38,000. Both would be read in the same direction. The first open reading frame corresponds to the par A gene, the Mr 44,000 protein product of which was shown to be trans acting and essential for partition. The second open reading frame (parB) follows closely and may be cotranscribed with par A. The codon usage frequency for parB is consistent with its producing a protein product. The ParB protein was identified in cell extracts as a product with an apparent Mr of 45,000, suggesting that it behaves anomolously on gel electrophoresis. Following parB is the incB region, an incompatibility determinant thought to be the cis acting site that constitutes the putative attachment point on the DNA for the cellular partition apparatus. Subcloning of this site showed it to consist of a maximum of 174 base-pairs. The incB sequence is highly A + T-rich and contains a 20 base-pair inverted repeat. Another A + T-rich inverted repeat of similar size but different sequence is found between the putative parA promoter and the ribosome initiation sequence at the start of the parA open reading frame and may be involved in the autoregulation of ParA synthesis. The par region appears to contain a functional analog of the centromere of eukaryotic chromosomes. It is responsible for ensuring that newly replicated plasmids are properly distributed to daughter cells during cell division of its Escherichia coli host.
We initiated a retrospective study to determine whether ST segment depression seen in inferior leads (II, III, and aVF) during acute anterior myocardial infarction (MI) is a reciprocal change or an independent sign of ischemia of additional myocardium. We selected 20 patients with anterior MI and attempted to compare findings of subsequent cardiac catheterization and the clinical course of 14 patients with ST segment depression (group A) and six without ST segment depression (group B). Patients in group A had a higher prevalence of right coronary artery disease (13 vs 0, P less than .01), multivessel disease (14 vs two, P less than .01), inferior wall motion abnormalities (seven vs 0, P less than .01), and ejection fraction of less than .50 (ten vs two, P greater than .05) than those in group B. A greater number of patients in group A had serious in-hospital and follow-up complications (12 vs two, P less than .05). We conclude that ST depression in leads II, III and aVF during acute anterior MI is not "reciprocal change" but a high-risk indicator.
The evaluation of an emergency room patient with acute chest pain is often difficult. Recently, computers have been employed to develop protocols for identifying which patients are likely to have acute myocardial infarctions and to benefit, therefore, from admission to a relatively scarce coronary care unit bed. We have tested the latest computer-derived instrument in a municipal hospital and found it to be less reliable than the clinical judgement of physicians.
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Anaphylactic sensitivity to her husband's seminal fluid occurred in a 46-year-old woman six weeks after a hysterectomy. Her husband was azoospermic as a result of an elective vasectomy. A pooled sample of his seminal fluid was used for skin and laboratory tests. Fractionating (Sephadex G100) chromatography was also performed on his seminal fluid. The patient showed positive intracutaneous skin tests to his unfractionated seminal plasma and a Sephadex G100 fraction designated No. 3. This fraction was also passively transferable to a nonallergic volunteer and it stimulated histamine release from the patient's leukocytes. The dose-response effects of this fraction compared with unfractionated seminal plasma in these assays showed greater bioactivity. After informed consent was obtained, the patient was immunized to fraction 3 in a classic desensitization protocol. Two weeks after the final dose of immunotherapy, intercourse was performed without condoms in a medical facility and under the supervision of a physician. No adverse symptoms were experienced by the patient on this occasion. Regular and frequent sexual activity is required to maintain her tolerant state.