Showing papers by "Texas Medical Center published in 1980"

Tensile fracture of cancellous bone

Abstract: Excised specimens of cancellous bone from human femora were subjected to compressive or tensile testing, and the resulting force-displacement curves were recorded. The relationships between bone strength and apparent density were similar for specimens tested in these two loading modes. The modulus of elasticity was also comparable for the tensile and compressive specimens. Specimens loaded in compression absorbed considerable energy after the initial fracture because of progressive impaction of the trabeculae. In the specimens loaded in tension, the fractured bone fragments separated and therefore absorbed little additional energy after the initial failure. The energy absorption capacity was thus significantly lower for the tensile specimens. The results of this study show that the primary difference in mechanical properties of cancellous bone tested in tension and compression is the energy absorption capacity. This finding suggests that tensile and avulsion fractures of cancellous bone observed clinically are associated with minimal energy absorption and therefore may be precipitated by relatively minor trauma.

Viruses as agents of airborne contagion.

Abstract: The concept of airborne contagion is ancient, but serious study of airborne contagion had its beginning in the 1930s and received further impetus in World War 11 because of problems of respiratory illness in military populations. William Furth Wells, who was preeminent in developing knowledge of airborne infection in those years, has summarized events to about 1950 in a monograph published for the Commonwealth Fund.' His concepts seem valid today. The early studies on airborne transmission dealt almost exclusively with bacterial diseases while the problem of airborne viral disease had to await the development of virology as a discipline after World War 11. The greatest recent contributions to understanding of airborne infection came from the extensive studies of the U S . Army Chemical Corps Biological Laboratories at Fort Detrick, Maryland, and from a similar institution, the Microbiological Research Establishment at Porton, England, during and after World War 11. My colleagues and I began studies of airborne viral infections in 1961, and our work was greatly benefitted by collaboration with the group at Fort Detrick. In recent years interest in the problem of airborne viral disease has waned, partly because of reduced activity at Fort Detrick and lack of interest of the civilian community in the problem. The present situation seems to be that by inference, many viral infections are disseminated by the airborne route, but proved instances of such transmission are few. In the future, we need to follow the spread of infections from their source in the infected patient to their implantation on the mucous membranes of the susceptible host. To get a proper perspective we should study both airborne and the various forms of contact spread of infection. This is not an easy assignment, but interrupting transmission effectively will require more precise knowledge than we now possess. The following report reviews the physical properties of aerosols that influence their distribution and the characteristics of viruses that influence their capacity to function as infections agents in aerosol.

Non-invasive bronchial epithelial papillary tumors.

Abstract: Nineteen papillary, non-invasive tumors arising from the bronchial epithelium but excluding carcinoid tumors are reviewed. Eight were solitary papillomas of which three were covered with a mixture of epithelial types. Seven were benign but one had a focus of carcinoma in situ. A similar change was seen in bronchial epithelium adjacent to a papilloma. Two cases of recurrent papillomas were seen and in one, carcinomatous changes eventually occurred. Two combined benign brochial cystadenomas with papillomas are described. One transitional celled papillary carcinoma in situ and five other papillary carcinomas in situ are described. One bronchial papilloma covered with dysplastic epithelium was considered an intermediate stage in the development of carcinoma in situ. Two papillary tumors may have arisen from peripheral bronchi or brochioles. Their lining cells resembled Clara cells, they grew by local expansion, and there was an absence of malignant features. The differential characteristics of two secondary carcinomatous polypoidal tumors are described.

Intergroup Ewing's Sarcoma Study Local Control Related to Radiation Dose, Volume, and Site of Primary Lesion in Ewing's Sarcoma

Abstract: One hundred ninety-three patients with localized Ewing's sarcoma treated at participating instutitions of the Intergroup Ewing's Sarcoma Study form the basis for this report. All patients received radiation therapy to the primary lesion and were randomized to receive vincristine, actinomycin-D, and cyclophosphamide (VAC) plus adriamycin (Regimen I); VAC alone (Regimen II); or VAC and bilateral pulmonary irradiation (Regimen III). Local control was achieved in 96% of the patients in Regimen I, and 86% of the patients in both Regimens II and III. The median duration of follow up was 83 weeks and median survival time was 172 weeks. Incremental doses of irradiation did not result in significant changes in the rate of local control of primary lesions. The local control rate was the same (92%) for tumors treated by means of whole-bone irradiation or with at least 5 cm of free margin around the lesion. The local control rate decreased to 79% for lesions treated with less than 5-cm margin. Excellent control was obtained for lesions involving the skull or spine (100%), and distal bones (fibula, 96% and tibia, 91%). Less favorable control rates were noted for pelvic and humeral lesions (84% and 79%, respectively). Bilateral pulmonary irradiation for subclinical disease played a role in lowering the incidence of lung metastases from 38% to 20% for patients treated with VAC. Lung metastases were similarly decreased (10%) when adriamycin was added to VAC chemotherapy.

Phospholipid binding studies with synthetic apolipoprotein fragments

Abstract: The plasma lipoproteins are macromolecular complexes of lipids and proteins and are the major carriers of triglycerides, cholesterol, cholesteryl esters, and phospholipids in the blood stream (TABLE 1 ) (see Reference 1 for a recent review). Several of the apoproteins, in addition to associating with lipids, have been shown to interact with enzymes and cell surface receptors to control lipid metabolism. The role of apolipoprotein B (apoB) and low-density lipoproteins (LDL) in cholesterol synthesis has been extensively studied by Brown and Goldstein and others2 The role of apoC-I1 in the activation of lipoprotein lipase for hydrolysis of chylomicron and very-low-density lipoprotein (VLDL) triglycerides is also well established.\", Apolipoproteins A-I and C-I are known to activate lecithin: cholesterol acyltransferase, the enzyme believed to be primarily responsible for the synthesis of cholesteryl esters.5The serum apolipoproteins have been shown by many investigators to interact with phospholipids, cholesterol, cholesteryl esters, and triglycerides to reform stable protein-lipid complexe~.~ In the process of binding lipids, the apoproteins show increases in their circular dichroic (CD) spectra at 208 and 222 nm, characteristic of the formation of an a helix. The intrinsic tryptophan fluorescence spectrum shifts from -350 nm to -335 nm; this shift has been interpreted as the tryptophan being placed in a more hydrophobic environment. These spectroscopic changes have been used as criteria of lipid binding.? In addition, phospholipid binding has been evaluated by differential scanning calorimetry, microcalorimetry, by measuring the decrease in lipid turbidity, and by the ability to isolate stable lipid-protein complexes by density gradient ultracentrifugation or agarose column chromatography.' In 1971, as the sequences of the apolipoproteins became available, we began a program of peptide synthesis, the goal of which was to determine the structural features necessary for lipid binding. In addition, as the sequences became known of the three apoproteins that interact with the enzymes responsible for the metabolism of lipids, we undertook the additional task of defining the minimum sequence requirements for enzymic activation.

Changes in RNA polymerase II in a cell cycle-specific temperature-sensitive mutant of hamster cells.

Abstract: tsAF8 cells are a temperature-sensitive mutant of BHK cells that arrest at the nonpermissive temperature in the G1 phase of the cell cycle. The activity of solubilized RNA polymerase II and its ability to bine [3H]-gamma-amanitin decrease in tsAF8 cells at 40.6 degrees, with a half-life of approximately 10 hr. No appreciable changes occur in these two parameters in tsAF8 cells at 34 degrees or in BHK cells at either 34 degrees or 40.6 degrees. Protein synthesis is not appreciably affected for at least 24 hr after tsAF8 cells are shifted to 40.6 degrees. These results indicate that in tsAF8 cells at the nonpermissive temperature, there is a defect in either the synthesis, the assembly, or the stability of RNA polymerase II, and that the loss of RNA polymerase II molecules is not due to widespread cellular damage.

Activation of lipoprotein lipase by synthetic fragments of apolipoprotein c‐ii *

Abstract: Fatty acids released from dietary fat during digestion, except for short chain fatty acids, enter the circulation in the form of chylomicrons. Circulating triglycerides also originate from the liver as very-low-density lipoproteins (VLDL) , which carry triglycerides to nonhepatic tissues for utilization or storage. One of the most important metabolic interconversions of lipoproteins occurs in the vascular compartment of the body and involves lipoprotein lipase, which catalyzes the hydrolysis of triglyceride. This enzymatic process at capillary endothelium is the key event in the removal of circulating triglyceride from the plasma. In humans, there appears to be little, if any, uptake of intact triglyceride-rich lip~proteins.l-~ Lipoprotein lipase has an additional essential ro!e in the formation of the cholesteryl-ester-rich low-density lipoproteins (LDL) , the lipoproteins most closely associated with atheroscler~sis.~ The metabolic precursors of LDL are secreted from the intestine or from the liver in response to cellular synthesis of triglyceride. In man under normal circumstances, greater than 95% of the circulating LDL originates from the triglyceride-rich lipoproteins by the action of lipoprotein lipase.6 Another metabolically important role has been identified by recent studies that demonstrate the conversion in vitro of high-density lipoprotein-3 (HDL,) to HDL, in the presence of VLDL and lipoprotein lipase.' These latter results provide a reasonable explanation for the frequently observed reciprocal relationship of plasma VLDL and HDL levels. Thus, lipo-

Laparotomy findings in lymphangiogram-staged I and II non-Hodgkin's lymphomas

Abstract: Ninety patients with Stage 1 or 11, including extranodal (E), presentations of non-Hodkin's lymphoma were investigated by laparotomy, either for the definitive staging of patients with peripheral presentations or for diagnosis of abdominal disease. Sixty-eight patients had staging laparotomies after extensive work-up, which included lymphangiography and bone marrow biopsy. The remaining 22 patients had laparotomies for diagnosis of abdominal symptoms or for management of unrelated surgical problems, with lyphoma being found incidentally. The incidence of positive abdominal findings in the 68 patients who had staging laparotomies depended on histologic subtype. In nodular lymphoma patients, abdominal disease was found in 17 of 28 (61%) and in diffuse lymphoma patients, in 9 of 40 (22.5%). For patients with nodular lymphomas upstaged by laparotomy, the positive findings tended to cluster around an axis consisting of the celiac, porta-hepatic, para-aortic, and root of the mesentery lymph nodes. In addition, 64% of these patients had splenic involvement. For the diffuse lymphomas upstaged by laparotomy, the distribution of positive findings was similar to that of the nodular lymphoma group; however, only 1 patient had splenic involvement. By contrast, in approximately half of the diffuse lymphoma patients who had laparotomies for diagnosis, the gastrointestinal tract was found to be involved in addition to the previously cited lymph nodes. Cancer 452778-2786, 1980.

Real-Time Sonography: Ventricular and Vascular Anatomy of the Fetal Brain in Utero

Abstract: Detailed fetal intracranial anatomy can be examined in utero using real-time sonography. The ability to demonstrate motion makes it possible to visualize important vascular landmarks which are helpful in identifying adjacent structures and in recognizing appropriate planes of section. The lateral ventricular system can be demonstrated and the lateral ventricular ratio can be determined in cases beyond 27 weeks gestation if the head is in an occiput transverse position. A lateral ventricular ratio greater than 0.45 (bodies) or greater than 0.65 (atrium) should raise the question of hydrocephalus and close follow-up measurements of the biparietal diameter, the head circumference/abdominal circumference ratio, and the lateral ventricular system should be made to evaluate this possibility. The fetal third ventricle is not routinely visualized before 34 weeks gestation in the absence of hydrocephalus; alternative anatomic explantations for the structure commonly referred to in the literature as the fetal third ventricle are discussed.

Evaluation of the significance of prognostic factors in stage III Hodgkin's disease treated with MOPP and radiotherapy.

Abstract: One hundred consecutive Stage IIIA and IIIB Hodgkin's disease patients were treated between July 1969 and September 1976, on a combined chemotherapy-radiotherapy program consisting of two courses of MOPP followed by radiotherapy to the mantle, abdomen, and pelvis. Eighty-eight patients completed radiotherapy to all disease sites. At the time of this analysis, the mean follow-up period for the 100 patients was 45 months; 70 patients had been followed three to seven years. Projected five-year survival and disease-free survival figures for the 100 patients were 80% and 68% respectively; corresponding results for the 88 patients were 90% and 78%. To determine whether any of the following prognostic factors influenced results for either the 100 or the 88 patients, survival curves were calculated for age, sex, constitutional symptoms, histopathology, method of staging, and status of the mediastinum. Other than age, none of these factors influenced survival significantly. However, disease-free survival figures were influenced adversely by mediastinal disease as well as age.

Study of sensation and muscle twitch responses to spinal cord stimulation

Abstract: Electrically induced sensation and muscle twitches were studied in a group of 43 patients in whom epidural electrodes were percutaneously placed for the evaluation of the effect of spinal cord stimulation on modification of their unpaired motor control. Mean stimulus strength for sensory threshold was 5.25 ± 2.75 mA and the tolerance level was at the stimulus strength of 10.8 ± 4.4 mA. Muscle twitches with short latencies were recorded in limb and trunk muscles within the segments at the stimulating cathode. Exceptionally, higher stimuli elicited muscle twitches of distant segments.

Gerontologic and geriatric training in medical school: curricular preferences shown by medical students, educators, and general practitioners.

Abstract: The need for incorporating gerontologic and geriatric training into the education of medical students is evident. Two main obstacles are the lack of educator knowledge in planning such training, and negative attitudes toward aging and the aged. Curriculum planning requires a design for the goals/objectives, the content, and the delivery vehicles. This article concerns chiefly the delivery vehicles, a subject which has received little attention in the literature. Negative attitudes on the part of students and their educators may defeat the incorporation of geriatric training into the curriculum. To assist in reducing these obstacles, a study was conducted for the purpose of providing data to educators which might facilitate the design of a delivery component for a medical student curriculum in gerontology and geriatrics. Senior medical students, their educators, and some general practitioners were surveyed in randomized groups, to determine: 1) their preferences for delivery vehicles in such a curriculum, 2) their attitudes toward aging and the aged, and 3) relevant demographic variables. The results are discussed from the viewpoint of the potential impact of these factors on their preferences and on the creation of obstacles to curriculum incorporation.

Studies on the Primary Structure of Apolipoprotein B

Abstract: Recent years have seen considerable accumulation of physical-chemical and functional data concerning the low-density lipoproteins (LDL) . Elegant studies designed to demonstrate core regions of cholesteryl esters which perform cooperative phase transitions have been well-documented.1-3 Low angle xray and neutron scattering experiments suggest a quasispherical structure with protein and polar lipids surrounding a nonpolar lipid core. Functionally LDL interacts with a variety of cells by a high-affinity receptor, presumably to the protein, which initiates a series of events all aimed at cellular control of cholesterol synthesis.' Such intensity of interest about the LDL particle has been justified by the epidemiological suggestion that it is directly involved in the atherogenic process.8 In spite of all that has been documented concerning the structure and function of low-density lipoproteins, the characterization of perhaps its most important component, that of the apoprotein, remains uniquely obscure. Handling of the apoprotein has proven a test (of abilities and patience) to anyone who has attempted it. If one has not worked with the apoprotein of LDL, it is difficult to understand all the fuss over it. That this protein presents a unique chemical problem is apparent by the fact that, although for many years apolipoprotein B (apoB) has been an intensely studied moiety, and large quantities are readily available, very little is confidently known about the apolipoprotein. In our attempts to obtain primary sequence data on the apoprotein, we have continually struggled with the solubility and aggregation problems associated not only with the protein but also with fragments of apoB. Some of the problems with the cyanogen bromide peptides have been discussed by us and l1 In the following report, we outline our recent approaches to obtaining chemical and sequence information on apoB. Because of the difficulties involved in working with both the apoprotein and its fragments, we emphasize some of the problems that we have encountered in the hope that our experiences will be of aid to others. The bulk of data presented here will concern the initial attempts to isolate, purify, and characterize the peptides generated from intact LDL by tryptic digestion. We will demonstrate that enumerable purification steps were often necessary, leading to overall low yields. We also suggest that several peptides are from partial cleavages, probably leading