Showing papers by "Medical University of South Carolina published in 1979"

The aftermath of rape: recent empirical findings.

Abstract: In a longitudinal study of the effects of rape on a woman's subsequent psychological functioning, objective measures of mood state and psychological distress were obtained at four intervals from 46 recent rape victims and 35 nonvictims. Initial response to rape was characterized by intense generalized distress. Three months and six months later, this distress had diminished, leaving a residual of fear and anxiety problems that were clearly rape-related. Implications for treatment are discussed.

Compressive Fatigue Limits of Composite Restorative Materials

Abstract: Compressive fatigue limits at 5,000 stress cycles have been measured for seven commercial composite restorative materials. The average of the ratios between fatigue limit and compressive strengths is 0.64.

Are all recently detoxified alcoholics depressed

Abstract: Reports of the prevalence of depression among alcoholics vary from 3% to 98%; the authors attribute this variation to the use of different diagnostic criteria. They used clinical diagnosis, the Hamilton Depression Rating Scale, the Zung Self-Rating Depression Scale, and the MMPI to diagnose 35 men recently withdrawn from alcohol. The percentages of depression diagnosed were 8.6%, 28%, 66%, and 43%, respectively. The authors point out that the Hamilton, Zung, and MMPI scales are not diagnostic of depression in themselves and that accurate diagnosis of depression in alcoholics will reduce inappropriate treatment of nondepressed alcoholics and ensure careful treatment of the truly depressed.

Blood pressure, heart rate, pressure-rate product and electrocardiographic changes in healthy children during treadmill exercise

Abstract: Heart rate, systolic and diastolic blood pressure, rate-pressure product and electrocardiographic changes were measured in 288 healthy children during treadmill exercise A constant speed (35 miles/hour) protocol was used to facilitate the measurements of physiologic data during exercise Because responses to exercise vary with size, the children were separated into four groups according to body surface area Comparisons were also made between male and female and between black and white children The values for heart rate and systolic pressure showed excellent reproducibility in repeated tests These data establish for clinical use reference values for children during treadmill exercise

The effects of alpha adrenergic agents on human platelet aggregation

Abstract: The effects of alpha adrenergic agonists and antagonists on human in vitro platelet aggregation were studied to characterize further the platelet alpha adrenergic receptor. Aggregation induced by ADP and U46619; a stable prostaglandin endoperoxide analog, was potentiated by alpha adrenergic agonists, an effect which was completely blocked by the alpha adrenergic antagonist phentolamine (1 X 10(-6) M) but not by prazosin (1 X 10(-6) M). The order of potency for the alpha adrenergic agonists in potentiating ADP-induced aggregation was clonidine greater than or equal to epinephrine greater than alpha-methylnorepinephrine greater than norepinephrine greater than phenylephrine greater than methoxamine. Epinephrine-induced platelet aggregation was blocked by phentolamine, yohimbine, dihydroergotamine, clonidine and lofexidine but not by phenoxybenzamine (1 X 10(-5) M). These findings suggest that: 1)clonidine and lofexidine are partial agonists and 2) that the alpha adrenergic receptor of the platelet is different from the classical postsynaptic alpha adrenergic receptor and more closely resembles presynaptic alpha adrenergic receptors.

Development and validation of the Eating Behavior Inventory

Abstract: The Eating Behavior Inventory (EBI) is a self-report instrument for assessing behaviors that have been theoretically implicated in weight loss, e.g., self-monitoring of food intake and of weight, refusing offers of food, eating at only one place, shopping from a list, eating in response to emotions. Thirty items were constructed in the form of first-person statements, e.g., “I eat in the middle of the night.” Each item was to be rated with a 5-point scale according to how often it was true for the respondent. Items were scored such that higher scores always reflected more “appropriate” (theoretically facilitative of weight control) eating patterns. Validity of individual items and total score was assessed in four studies. Twenty-six of the original items appeared valid and were retained. The resulting total score demonstrated validity in these studies and in two cross-validational comparisons. Internal consistency as measured by split-half reliability and correlations of item scores with total score was acceptable. One month test-retest reliability of item and total scores was satisfactory. Clinical and research applications of the EBI are discussed.

Assessment of the aftermath of rape: Changing patterns of fear

Abstract: In order to test a social learning theory model which states that fear and anxiety responses are classically conditioned by a terror-inducing rape experience, 46 recent rape victims and 35 nonvictims matched for age, race, and neighborhood of residence were assessed with the 120-item Modified Fear Survey at four postrape intervals: (1) 6–10 days, (2) 1 month, (3) 3 months, and (4) 6 months. Victims were significantly more fearful than nonvictims, and victim fears declined somewhat over time but remained at high levels at the 6-month postrape period. Content analysis of highly feared situations revealed that most fears were rape related in that they were rape cues, rape-precipitated concerns, and/or cues signaling vulnerability to subsequent attack. Patterns of fear appeared to change such that attack vulnerability cues were most feared.

Characteristics of tissue growth into proplast and porous polyethylene implants in bone

Abstract: One objective of this study was to determine why fibrous tissue, not bone, forms in internal pores of Proplast implants even though the material is labeled as having pore characteristics compatible with bone ingrowth. A second objective was to assess the suitability of the fibrous tissue in Proplast implants for supporting load-bearing prostheses. Thirty cylindrical rods of Proplast were implanted through the lateral diaphyseal cortex of eight dogs for periods of 1 to 20 weeks. Porous high density polyethylene was used as a „control” in the study since it is a low modulus polymer which does undergo bone ingrowth. Twenty rods of porous polyethylene (400 μm average pore size) were implanted in the experimental animals along with the Proplast. Postmortem specimens were prepared for microradiography and histological evaluation. Optical point-counting techniques and mercury intrusion porosimetry were used to determine the pore characteristics of the materials. Microradiography and histological evaluation revealed bone growth throughout the porous polyethylene implants. In contrast, bone growth was only occasionally observed in surface pores of the Proplast. However, bone completely filled Proplast specimens which were teased to purposely enlarge the pores of the material prior to implantation. This observation, along with the pore analyses which revealed an average pore size of only 75 μm and interconnecting pores less than 50 μm in diameter, led to the conclusion that fibrous tissue, not bone, forms in Proplast specimens because of the small pore size of the material. Further, the results demonstrated that there was no collagen continuity of the fibrous tissue in the pores of the material with surrounding bone (e.g., no Sharpey' fibers) suggesting that the load-bearing support which can be afforded by Proplast implants is limited by the incomplete bone ingrowth along the margins of the material and the tensile strength of Proplast.

Trophoblast Transferrin and Transferrin Receptors in the Host-Parasite Relationship of Human Pregnancy

Abstract: Transferrin and specific transferrin receptors are demonstrated on the microvillous surface of syncytiotrophoblast in human immature and term placentae by immunohistological techniques with the use of light and electron microscopy. That the distribution of transferrin is limited to the materno-foetal interface supports the hypothesis that binding of maternal transferrin to trophoblast receptors is involved in the process of iron transport to the foetus. Parallel studies with baboon placentae demonstrate the presence of trophoblast receptors which bind both baboon and human transferrin, thereby putting forward an experimental model which might be used to test the biological significance of placental transferrin receptors in primates. In addition, investigation of a large number of human cell lines shows that many transformed cells, but no normal cells (such as blood lymphocytes) or cells from primary culture (such as neonatal foreskin fibroblasts), possess the ability to bind transferrin to their membranes. These findings suggest that transferrin receptors may play important biological roles in addition to that of iron transport from mother to foetus. One such role could be the limitation of iron in intervillous spaces, thus depriving iron-requiring microorganisms of iron, hence serving as a non-specific factor of resistance for placentae. Another role for foetal transferrin receptors on trophoblasts could be to bind maternal transferrin at the materno-foetal interface, thus frustrating maternal immunosurveillance. This is similar to a mechahism used by schistosomes in the host-parasite relation where host proteins are bound by the parasite to escape immunological recognition. The presence of transferrin receptors on transformed cells suggests that this mechanism might also be employed by tumour cells. Finally, in view of previous studies which show that transferrin is required by stimulated lymphocytes to pass from the G$_{1}$ to the S phase of cellular replication, it is proposed that trophoblast transferrin receptors could limit the amount of transferrin in intervillous spaces and thus impede the proliferation and possible cytotoxicity of maternal activated lymphocytes at the materno-foetal interface.

Isolation of a Cytotoxin-Enterotoxin from Entamoeba histolytica

Abstract: A heat-labile material with cytotoxic and enterotoxic activities was isolated from axenically cultivated Entamoeba histolytica. The cytotoxin-enterotoxin was partially purified from the particulate-free supernatant of sonicated trophozoites by ammonium sulfate precipitation and gel filtration. Cytotoxic activity, assayed on monolayers of HeLa or BHK-21 cells, was restricted to proteins that eluted in the molecular weight range of 25,000--35,000 daltons. Cytotoxicity was demonstrated at protein concentrations as low as 2--4 microgram/ml, was heat-labile (75 C, 30 min), and was inhibited by specific immune IgG and by an undetermined factor in nonimmune serum. Enterotoxic activity of the partially purified toxin was demonstrated by induction of fluid secretion in ligated rabbit ileal loops. The cytotoxin-enterotoxin of E. histolytica may play an important role in the production of diarrhea and mucosal injury in amoebic colitis.

Release of a two-chain form of antithrombin from the antithrombin-thrombin complex.

Abstract: The stable, inactive complex between antithrombin and thrombin was prepared and subsequently purified free of reactants by a procedure which minimized secondary thrombin proteolysis. Dissociation of the complex was effected by hydroxylamine or ammonia in the presence or absence of sodium dodecyl sulphate, or by prolonged treatment at 100°C in the presence of dodecyl sulphate. All these procedures released from the complex a proteolytically modified, two-chain form of antithrombin and not the intact protein. Dissociation in the absence of denaturant also released active thrombin. Control experiments indicated that the inhibitor was indeed released from the complex as the modified form of antithrombin rather than as intact antithrombin which was subsequently modified by the dissociation agents or by thrombin. The modified form of antithrombin dissociated from the complex could not be differentiated electrophoretically from a proteolytically modified, inactive form of antithrombin which has been shown previously to be produced free in solution during the reaction between antithrombin and thrombin. These observations suggest that limited proteolysis of antithrombin by thrombin may be involved in the formation of the inactive complex. The inhibitor may thus exist in the complex as a proteolytically modified, two-chain species. However, a state in which the scissilc peptide bond of the inhibitor only forms a tetrahedral adduct with the active site serine of the enzyme, as shown by X-ray crystallography in other protease-protease inhibitor complexes, cannot be excluded.

Evolution of multiple-antibiotic-resistance plasmids mediated by transposable plasmid deoxyribonucleic acid sequences.

Abstract: Two plasmid deoxyribonucleic acid sequences mediating multiple antibiotic resistance transposed in vivo between coexisting plasmids in clinical isolates of Serratia marcescens. This event resulted in the evolution of a transferable multiresistance plasmid. Both sequences, designated in Tn1699 and Tn1700, were flanked by inverted deoxyribonucleic acid repetitions and could transpose between replicons independently of the Excherichia coli recA gene function. Tn1699 and Tn1700 mediated ampicillin, carbenicillin, kanamycin, and gentamicin resistance but differed in the type of gentamicin-acetyltransferase enzymes that they encoded. The structural genes for these enzymes share a great deal of polynucleotide sequence similarity despite their phenotypic differences. The transposition of Tn1699 and Tn1700 to coresident transferable plasmids has contributed to the dissemination of antibiotic resistance among other gram-negative bacteria. These organisms have recently caused nosocomial infections in epidemic proportions.

Presystemic and systemic glucuronidation of propranolol.

Abstract: The relative importance of presystemic and systemic glucuronidation of propranolol was examined in normal subjects given single oral and intravenous doses of propranolol. The areas under the plasma concentration--time curves (AUCs) of propranolol glucuronide (PG), 41 +/- 15 ng . hr/ml, and propranolol, 48 +/- 15 ng . hr/ml, were of the same order after the intravenous dose (0.05 mg/kg). After oral doses of 20 and 80 mg, the AUCs of PG were 302 +/- 105 and 1,398 +/- 409 ng . hr/ml; these were 7 times the AUCs of propranolol, 44 +/- 15 and 220 +/- 38 ng . hr/ml. The time lapse to peak concentration, 1.5 to 3.0 hr, and the plasma half-life, 3.2 to 3.7 hr, were the same for PG and propranolol. These results demonstrate glucuronidation as an important determinant of propranolol bioavailability.

Transposable plasmid deoxyribonucleic acid sequence in Pseudomonas aeruginosa which mediates resistance to gentamicin and four other antimicrobial agents.

Abstract: A 9.1 x 10(6)-dalton transposable deoxyribonucleic acid sequence resides within Pseudomonas aeruginosa plasmid R1033 and mediates resistance to gentamicin, streptomycin, sulfamethoxazole, chloramphenicol, and mercuric chloride. Transposability was demonstrated in Escherichia coli when this sequence, designated Tn1696, excised from R1033 and integrated into plasmid pMB8. Excision and insertion of Tn1696 occurred independently of the host Rec phenotype and may involve the 140-base pair, inverted deoxyribonucleic acid repeated region that flanks this sequence. Occurrence of a multiresistance transposon on a transferrable plasmid that has a broad host range may have serious epidemiological and therapeutic consequences.

Morphogenesis of the truncus arteriosus of the chick embryo heart: the formation and migration of mesenchymal tissue.

Abstract: The appearance and migration of mesenchymal cushion tissue within the truncus arteriosus of the normal 2.5 to 6-day chick embryo heart was surveyed systemically with the light microscope. Series of cross-sections taken from replicate hearts at successive developmental stages allowed comparison of the following qualitative and quantitative aspects of early truncal morphogenesis. Mesenchyme within the truncus was derived from two distinct sources. The first mesenchyme appeared to migrate caudally into the cardiac jelly of the distal truncus from the nearby aortic arch region, coincident with slowing of the anterior elongation of the heart tube (Hamburger-Hamilton Stage 17-18). A second, separate mesenchymal population, derived from endocardium, began to fill the conus and proximal truncus in a radial direction, coicident with expansion of the bulbs cordis (Stage 12-19). The measured kinetics of relative cell numbers, distributions, and mitotic indices suggest substantial contributions from both sources. By Stage 26, the conotruncal region was filled with mesenchyme, which then condensed to form the anlagen of three future structures: the semilunar valves, the aorticopulmonary septum, and the tunica media of the great arteries.

Morphogenesis of the truncus arteriosus of the chick embryo heart: tissue reorganization during septation.

Abstract: Septation of the truncus arteriosus of the normal chick embryo heart was surveyed systematically with the light microscope. Tissue from replicate samples at successive periods of development was sectioned within an arbitrary coordinate system based on positional reference points along the external surface of the heart. Correlation of several aspects of tissue morphology within this spatial and temporal reference-frame yielded a new description of tissue associations and kinetics during septation. A stable complex of tissue structures appeared in the downstream, distal truncus at Stage 25 and persisted throughout the septation process. This complex consisted of (1) the cephalic margin of the myocardial sheath, and (2) the adjacent bifurcation of the vascular lumen, linked together by (3) the newly condensed Y-shaped strap of cells forming the aorticopulmonary septum. The apparent motion of this septation-complex toward the ventricle(s), the appearance within the thoracic cavity of the adjacent segments of the aortic arches, and measures of tissue length and width suggested that septation was accompanied, and perhaps initiated, by increased tension along the truncus. The truncal ridges remained upstream from the complex, with mesenchymal condensations beneath the endocardium differentiating into the definitive semilunar valves. Downstream from the bifurcation, mesenchyme in the aortic arch region condensed around the separate lumens to form the smooth muscular tunica media of the great arteries. The epicardium developed in a caudocephalic direction along the heart tube. Vagal innervation approached the heart cephalocaudally. Capillaries formed along the dividing truncus in both directions. Autoradiography following 3H-thymidine labelling demonstrated reduced DNA synthetic activity in the cephalic margin of the myocardium and aorticopulmonary septum, compared with the associated loose mesenchyme.

Proposed nomenclature for PNS myelin proteins.

Abstract: Peripheral nervous system (PNS) myelin, while having a relatively simple protein profile compared to plasma membranes when viewed on SDS gel electrophoresis, is more complex than central nervous system myelin. It appears appropriate and timely, therefore, at this early stage of our understanding of PNS myelin proteins, to adopt a uniform convention for naming of the PNS myelin proteins. We believe it will simplify the literature on this subject and limit confusion for present and future investigators. A typical polyacrylamide gel electrophoresis (PAGE) pattern for rabbit sciatic nerve myelin is shown in Figure 1; human and chicken sciatic nerve myelin show similar patterns. The major protein, at 28K, and the fastest moving protein, at 14K, have been designated as the PO protein and the P2 protein by Greenfield et al. (7) and Brostoff et al. (1). The PO protein was isolated in 1975 from rabbit sciatic nerve myelin by Brostoff et al. (3), and as reported by Greenfield et al. (7). It was also