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Biomedical subjects

R G Allen

Publications and source records attributed to R G Allen.

At least 127 records · Page 7Linked to original sources
PubMed1981

Strain differences in pituitary beta-endorphin and ACTH content in inbred mice.

The whole pituitary contents of beta-endorphin and ACTH were found to vary widely among 5 inbred strains of mice. beta-endorphin values were 2.5-fold different and ACTH values 1.5-fold. Strains low in beta-endorphin were also low in ACTH. The existence of genetic differences raises the possibility that there exist, or can be developed, strains with extremely low or high levels of these peptides that would aid research directed at elucidating the physiology of opioid peptides.

Adrenocorticotropic Hormone↗
PubMed1981

Perceptual distortions in visual-evoked potentials.

We tested ten healthy men, ranging in age from 24 to 55 years, to determine whether "drifting" of a fixation target during pattern-stimulus testing was the result of stimulus-induced ocular movements or a purely perceptual response with no oculomotor basis. We also wanted to learn whether this drifting interfered with the development of the visual-evoked potential. We observed large intersubject differences in visual-evoked potential magnitude that could not be explained by either actual or perceived drifting. Perceived drifting did not correlate with actual or perceived drifting. Perceived drifting did not correlate with actual ocular movements. Moreover, when sporadic ocular movements occurred, they did not interfere with the visual-evoked potential; there were no correlations between magnitude of visual-evoked potential and the percentage of time that drifting was perceived.

Adult↗
PubMed1981

Traumatic aortic aneurysm in a child.

The clinical presentation and diagnostic evaluation of a 2-yr-old boy with traumatic aortic aneurysm and aortic regurgitation is presented. Traumatic aortic aneurysms are extremely rare in childhood. To our knowledge this is the youngest reported patient with such pathology.

Aorta, Thoracic↗
PubMed1980

Methods of management and results following surgery for coarctation of the aorta in infancy.

There were 30 infants, under 1 yr of age, in refractory congestive heart failure, who underwent surgical correction for coarctation of the aorta. The series was divided into two groups, depending on the type of surgical procedure performed: Group 1, 17 patients end-to-end anastomosis; Group 2, 13 patients aortic angioplasty. Aortic angioplasty was carried out by three methods. Ten patients had a subclavian flap angioplasty as described by Waldhausen in 1966. In two patients a carotid artery flap angioplasty was used to enlarge a severely hypoplastic aortic arch distal to the left carotid artery. In one patient an onlay patch of pericardium was used to relieve obstruction across a coarcted segment. Mortality rates in this series and other series from the literature are primarily dependent upon associated cardiac anomalies. Mortality rates approach zero in infants operated on for coarctation who have no associated intracardiac anomalies. While the mortality rate was slightly lower in those patients treated by some type of angioplasty, the figures are too small to be significant. In this series and other series recoarctation is far less likely to occur after subclavian flap angioplasty in comparison to those patients undergoing end-to-end anastomosis. We would advise that in infants 1 yr of age, a subclavian or carotid flap angioplasty be used as a primary method of repair.

Aortic Coarctation↗
PubMed1980

Dose-response of guinea pigs experimentally infected with aerosols of Legionella pneumophila.

Experiments were carried out to determine the infectivity, clinical course of disease, and lethality of aerosols of Legionella pneumophila for guinea pigs. The median infectious dose was less than 129 organisms; the 50% lethal dose was 1.4 x 10(5) organisms. In addition, the intraperitoneal 50% lethal dose was 3.0 x 10(6) cells, a value indicating that the organisms were less virulent by the intraperitoneal route than by aerosol. Nonfatal disease always included fever and weight loss. These signs were accompanied by sporadic bacteremia and dyspnea. Leukocyte counts were uninformative. In general, the severity of fever and extent of serologic (microagglutination titer) response were dose-related. The guinea pig may be used as a model for Legionnaires' disease, but the only dependable clinical criteria of infection after airborne challenge are weight loss, fever, and seroconversion.

Aerosols↗
PubMed1980

Liquid medium for growth of Legionella pneumophila.

The medium described is a simple yeast extract broth capable of growing large number of Legionella neumophila, the causative organism of Legionnaires disease. Filtration was chosen as a means of sterilization, since medium that was autoclaved did not support growth without the presence of Norite A. The filtered medium gave rapid cell growth and maintained the initial antigen production. The observed generation time was 99 min with a maximum cell population of 2 X 10(2) COLONY-FORMING UNITS PER ML IN APPROXIMATELY 40 H.

Bacteria↗
PubMed1980

The distribution of forms of adrenocorticotropin and beta-endorphin in normal, tumorous, and autopsy human anterior pituiary tissue: virtual absence of 13K adrenocorticotropin.

To begin to define the nature of the biosynthesis and processing of ACTH and beta-endorphin in the human, anterior pituitary tissue (fresh normal and adenomatous, and autopsy) was extracted in acetic acid in the presence of protease inhibitors and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The gel slice eluates were assayed for ACTH and beta-endorphin immunoactivity. Human anterior pituitary tissue contained four major size classes of ACTH and three major size classes of beta-endorphin. We found that in all tissue sources examined there was a virtual absence of 13-15K ACTH, which is a major form in the rat and mouse. When comparing extracts obtained from fresh normal or adenomatous anterior pituitary tissue, we also found a drastic decrease in beta-lipotropin and beta-endorphin in extracts of autopsy human anterior pituitaries. These results suggest that the biosynthesis and processing of pituitary ACTH and beta-endorphin in the human may be different than in the mouse, and because of apparent postmortem proteolysis of beta-endorphin, human pituitary obtained at autopsy is probably not a good source of material for biochemical studies of pituitary tissue.

Adenoma↗
PubMed1979

Simultaneous administration of live, enteric-coated adenovirus types 4, 7 and 21 vaccines: safety and immunogenicity.

The safety of and the immune response to simultaneous administration of live, enteric-coated adenovirus type 4 (ADV-4), type 7 (ADV-7), and type 21 (ADV-21) vaccines were studied. Volunteers (476 men), randomly assigned to four study groups, received three vaccines (ADV-4, ADV-7, and ADV-21), two vaccines (ADV-4 and ADV-7), one vaccine (ADV-21), or no vaccine (placebo). Subjects were observed for three weeks, and no side effects due to vaccination occured. The percentages of susceptible subjects (those entering the study with a neutralizing antibody titer of less than 1:2 to each vaccine virus received) who seroconverted to ADV-4 were similar in both groups that received ADV-4 vaccine (78% of 77 subjects and 74% of 76). However, in the group that received three vaccines, only 62% of 77 subjects seroconverted to ADV-7, compared with 79% of 76 in the group that received two vaccines (P less than 0.05). Only 58% of 77 subjects in the three-vaccine group seroconverted to ADV-21, compared with 69% of 59 in the group that received one vaccine (P greater than 0.1).

Acute Disease↗
PubMed1979

Immunologic protection against the Legionnaires' disease bacterium in the AKR/J mouse.

Female AKR/J mice were challenged with the Washington strain of Legionnaires' disease (LD) bacteria. Nonimmunized mice inoculate intraperitoneally with 2 x 10(8) colony forming units became ill within 4 h and died within 24 h. Progressive histopathologic changes initiated as early as 2 h after inoculation involved the lymphoid organs, the crypts of the small intestine, and the liver. Necrosis with minimal inflammatory cell reaction was the primary lesion. Immunization with a soluble LD bacterial antigen failed to prevent illness but protected against death and development of abnormal histologic changes.

Animals↗
PubMed1978

Coordinate control of corticotropin, beta-lipotropin, and beta-endorphin release in mouse pituitary cell cultures.

Hypothalamic extract stimulates the release of corticotropin (ACTH) and endorphins 2.5- to 30-fold in mouse pituitary tumor cell cultures (AtT-20/D(16v) line) and primary cell cultures from mouse anterior pituitary. ACTH and endorphin activities were measured by radioimmunoassay and immunoprecipitation. Pretreatment of tumor cell cultures with 1 muM dexamethasone reduced the stimulatory effect of the extract on release of ACTH and endorphins. Pretreatment of primary cell cultures with 10(-6) M dexamethasone reduced the stimulatory effect of both vasopressin and the extract on the release of ACTH and endorphins. Release of ACTH and endorphin was coupled in both kinds of cultures in the basal, stimulated, and inhibited states. The molecular weight forms of ACTH and endorphin in tumor cell culture medium were analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Radioimmunoassay and immunoprecipitation show that the 13,000-dalton and 4500-dalton forms of ACTH were present in about equal amounts in medium from cultures incubated with or without hypothalamic extract for 15 min, 30 min, or 2 hr. Smaller amounts of the high molecular weight forms of ACTH (20,000- to 23,000-dalton and 31,000-dalton ACTH) were observed in the culture medium at these times. The predominant forms of endorphin released after 20 min or 3 hr of incubation had molecular weights of 31,000, 11,700 (beta-lipotropic hormone-size material) and 3500 (beta-endorphin-size material). No degradation of the forms of endorphin released into the culture medium was observed after incubating the culture medium for 1.5 hr in the absence of cells. The proportions of the different forms of endorphin and ACTH present in the culture medium resembles that seen in cell extracts.

Adrenocorticotropic Hormone↗
PubMed1978

Reversal of dexamethasone inhibition of adrenocorticotropin release in a mouse pituitary tumor cell line either by growing cells in the absence of dexamethasone or by addition of hypothalamic extract.

Release of ACTH by a mouse pituitary tumor cell line )AtT-20/D-16v) is inhibited by 10(-8)-10(-6) M 9 alpha-fluoro-16 alpha-methyl-11 beta, 17 alpha, 21-trihydroxy-1,4-pregnadiene-3,20-dione (dexamethasone). Dexamethasone does not inhibit cell growth in this concentration range. Cortisol and corticosterone are almost as potent as dexamethasone in inhibiting ACTH release, whereas 17 beta-estradiol and testosterone have no effect. In rapidly growing cultures of tumor cells removal of dexamethasone leads to complete reversal of the inhibitory effect of the steroid on ACTH accumulation in culture medium within 4-5 days (3.5-4 generation times). The extent of reversal of the dexamethasone effect in slowly growing cultures (generation time 96-150 h) and in rapidly growing cultures (24-30 h) is proportional to the amount of growth that takes place in the absence of dexamethasone. Addition of hypothalamic extract to dexamethasone-treated cultures and to untreated cultures stimulates the release of ACTH 4- to 8-fold. The response occurs within 15 min after the addition of the extract and is dependent on the dose of the extract.

Adrenocorticotropic Hormone↗
PubMed1977

Modified Blalock shunts utilizing pericardial tube grafts.

In the last decade, 14 patients underwent an aorticpulmonary shunt for cyanotic heart disease, at which time the subclavian artery was either deemed too small or too short to function satisfactorily as a Blalock shunt. In each case a rectangular piece of pericardium was excised, rolled into a tube, and sutured down one edge to create a tube graft. One end of the graft was sutured to the stump of the subclavian artery near its takeoff and the other end was sutured end-to-side to the corresponding pulmonary artery. During the same period, 5 children had azygos vein grafts and 2 had Teflon grafts inserted to create a modified Blalock shunt. This article will discuss the indications, techniques, and long term results of aorticpulmonary shunts of all types, and more specifically the complications and long term results in patients where these grafts were used.

Adult↗
PubMed1977

Serodiagnosis of hepatitis B virus infection by antibody to core antigen.

In a military population antibody to hepatitis B core antigen (anti-HBc) was found in 39% of acute hepatitis cases negative for hepatitis B surface antigen (HBS Ag) and in 96% of HBs Ag-positive cases. Persistence of antibody to HBs Ag (anti-HBs) in convalescent-phase sera was significantly greater (P less than 0.001) in individuals with acute HBs Ag-positive hepatitis B than in patients with clinical HBs Ag-negative hepatitis B. The prevalence of anti-HBc in the absence of HBs Ag, anti-HBs, and clinical disease was 3.2% in this military population. In longitudinal studies of hepatitis B infection, the presence of anti-HBc preceded anti-HBs and improved the ability to determine the onset of sublicnical infection. Anti-HBc is a useful serologic marker for the study of the epidemiology of hepatitis B and improves the efficiency of detection of hepatitis B virus infection.

Animals↗