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Biomedical subjects

J R Davis

Publications and source records attributed to J R Davis.

At least 181 records · Page 10Linked to original sources
PubMed1989

Serum ammonia levels in response to glycine infusion in normal and cirrhotic rats.

Elevated serum ammonia may play a role in central nervous system derangement after transurethral resection of the prostate. Glycine used as a surgical irrigant for prostate resection produces ammonia as a by-product after liver and renal metabolism. The presence of liver dysfunction often leads to an inability to remove generated ammonia from the circulation. To determine whether the presence of cirrhosis allows significant metabolism of glycine and the resulting serum ammonia levels generated, the production of ammonia after glycine infusion was examined in normal and cirrhotic rats. Hepatic microsomal enzyme induction was produced in male Sprague-Dawley rats given sodium phenobarbital, added to the drinking water to hasten the development of cirrhosis, by increasing the toxicity of carbon tetrachloride given intragastrically to one group at weekly intervals for production of cirrhosis. A control group was maintained under similar conditions except for carbon tetrachloride dosing. The end point for production of cirrhosis was the development of ascites. Two weeks after the development of ascites in the cirrhotic rats and the discontinuation of phenobarbital in both groups, both control and cirrhotic rats were anesthetized with IP pentobarbital and glycine (1.25 g/kg; 7.5%) was given intravenously. Venous blood samples were taken at intervals up to 120 min for serum ammonia analysis. After the final serum ammonia sample, lethal pentobarbital injection was given and livers and kidneys removed for histologic analysis. Terminal body weight, glycine dose, and renal histology were not different between groups. Liver weights were greater in cirrhotic rats. Baseline serum ammonia levels were also greater int he cirrhotic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗
PubMed1989

Survey of cancer control attitudes among Missouri state legislators.

A number of cancer control efforts, while proven to be effective, require significant support from state and local lawmakers in order to be successful. This survey of state legislators' attitudes toward health risks and risk reduction measures that could be undertaken shows a favorable outlook for cancer control programs in Missouri.

Attitude to Health↗
PubMed1989

Tandem Y/6 translocation with partial deletion 6 (p23----pter).

An infant with multiple malformations had a de novo tandem translocation of the Y chromosome to chromosome 6. The karyotype 45,X,tan(Y;6) (q12;p23) resulted in a partial monosomy of 6p23----pter. Many of the effects of ring chromosome 6 are present in this case.

Abnormalities, Multiple↗
PubMed1988

Second-look laparotomy in epithelial ovarian carcinoma. Prognostic factors associated with survival duration.

This article that reports on 70 consecutive patients is one of only a few studies of advanced ovarian cancer that have attempted to define predictive factors associated with survival duration after second-look laparotomy. As in many other investigations, several factors have been analyzed for predicting second-look outcome. The prognostic variables analyzed in this study included age, stage, histologic grade, residual disease status after initial surgery, and type (cisplatin versus no cisplatin) and number of cycles of chemotherapy. Only stage (P = 0.002) and optimal disease (less than 2 cm residual tumor size) after initial surgery (P less than 0.001) were significantly associated with the absence of disease at second-look laparotomy, and both were significant predictors of second-look outcome in a multivariate logistic regression model. Their impact on actuarial survival after second-look laparotomy diminished, however. Actuarial survival after second-look laparotomy was associated with residual tumor size at second-look surgery (P = 0.02). According to second-look findings, the 3-year actuarial survival rates and standard errors were as follows: no pathologic evidence of disease, 80.7% +/- 13.4% 3-year survival; microscopic disease plus less than or equal to 2 cm residual disease, 49.1% +/- 13.1% survival; and gross residual disease (i.e., greater than 2 cm maximum tumor diameter), 29.5% +/- 11.4% survival. We also examined the effect of extensive tumor resection at second-look laparotomy on survival for patients with greater than 2 cm gross residual disease. Optimum resection (less than 2 cm residual tumor mass) resulted in significantly greater survival than suboptimum resection (P less than 0.001). This strongly suggests that there is a survival advantage associated with optimum resection at second-look laparotomy.

Actuarial Analysis↗
PubMed1988

Transmission of human immunodeficiency virus (HIV) by blood transfusions screened as negative for HIV antibody.

Since early 1985, blood donations in the United States have been screened for antibody to human immunodeficiency virus (HIV). To identify instances of HIV transmission by antibody-negative donations, we investigated 13 persons seropositive for HIV who had received blood from 7 donors who were screened as negative for HIV antibody at the time of donation. Twelve of the 13 recipients had no identifiable risk factors for HIV infection other than the transfusions they had received. On evaluation 8 to 20 months after transfusion, HIV-related illnesses had developed in three recipients, and the acquired immunodeficiency syndrome had developed in one. All seven donors were found to be infected with HIV. On interview, six reported a risk factor for HIV infection, and five had engaged in high-risk activities or had had an illness suggestive of acute retroviral syndrome within the four months preceding their HIV-seronegative donation. Thus, these donors had apparently been infected only recently, and so were negative at the time of blood donation according to available antibody tests. We conclude that there is a small but identifiable risk of HIV infection for recipients of screened blood. To minimize this risk, the reasons for deferral of donation need to be communicated more effectively to blood donors who are at high risk of HIV infection, and new assays that detect HIV infection earlier should be evaluated for their effectiveness in screening donated blood.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Identification of Mycobacterium tuberculosis in sputum by direct inoculation of the BACTEC NAP vial.

The Mycobacterium tuberculosis complex (M. tuberculosis, M. bovis, and M. africanum) can be differentiated from mycobacteria other than M. tuberculosis (MOTT bacilli) with the BACTEC NAP test (Johnston Laboratories, Becton, Dickinson & Co., Towson, MD), by selectively inhibiting their growth with p-nitro-alpha-acetyl-amino-beta-hydroxypropriophenone (NAP). The BACTEC NAP test is recommended for isolated mycobacterial cultures. In this report, a direct NAP test is performed by immediate inoculation of BACTEC NAP vials with processed sputum specimens that stain acid-fast positive. Seventy-six of 80 M. tuberculosis were correctly identified and all of the MOTT bacilli (nine M. avium complex and one M. kanasii) were correctly classified. The average time required for identification of M. tuberculosis with the direct BACTEC NAP test described here is more convenient than the recommended indirect test, and it is an accurate and rapid method to differentiate the M. tuberculosis complex from MOTT bacilli.

Bacteriological Techniques↗
PubMed1988

Direct antimicrobial drug susceptibility testing of Mycobacterium tuberculosis by the radiometric method.

Direct-drug-susceptibility tests were performed on clinical specimens positive for acid-fast bacilli by either Ziehl-Neelsen or fluorochrome staining. The results of conventional agar dilution (Vestal, 1975) and a modified radiometric (BACTEC) method were compared. A total of 580 smear-positive specimens were tested by the BACTEC method at three separate sites. Three hundred and seventy-seven of these were culture positive for M. tuberculosis, and 343 (91%) yielded acceptable direct-susceptibility-test results. We used the conventional method to determine that 343 of 519 smear-positive specimens were culture positive for M. tuberculosis, and 212 (62%) produced acceptable results within 3 wks. Conventional results were reported in 3-4 wks, while the time required to obtain results with the BACTEC method ranged from 5 to 21 days (average 11.5 days). Results indicate that the radiometric method provides reportable results more frequently with time savings as compared to the conventional method.

Bacteriological Techniques↗
PubMed1988

Correlation of DNA content and histology in prognosis of astrocytomas.

Thirty-two cases of astrocytoma were analyzed for DNA content and cell-cycle proliferation features by flow cytometry using paraffin-embedded tissue. The findings were correlated with histologic grading and survival. Abnormal DNA (aneuploidy or elevated G2-M fraction greater than or equal to 7%) was present in 18 cases (56%). Glioblastoma multiforme (GBM) had 11 of 16 (69%), anaplastic astrocytomas (ANA) 7 of 11 (64%), and low-grade (LG) neoplasms 0 of 5 cases with abnormal DNA content. Short-term survival (less than or equal to 26 months) occurred in all 16 patients with GBM (100%), 7 of 11 patients with ANA (64%), and 1 of 5 patients with LG neoplasms (20%). Seventeen of 18 patients (94%) with abnormal DNA content were short-term survivors (P less than 0.0002). Abnormal DNA content was found in 17 of 24 short-term survivors (71%), whereas histologic grading identified 16 of 24 such cases (67%). A combination of grading and abnormal DNA content identified 22 of 24 (92%) of the poor survival cases. DNA content was most useful in the anaplastic group. Six of seven cases (86%) with abnormal DNA content had short survival (P less than 0.055), and three of four (75%) with normal DNA content had long survival. DNA analysis combined with histologic grading improves prognosis designation.

Aneuploidy↗
PubMed1988

Dexamethasone-suppressible hyperaldosteronism: studies on overproduction of 18-hydroxycortisol in three affected family members.

We report a newly diagnosed family in which a father and his two sons were found to be hypertensive and to have the rare familial condition dexamethasone-suppressible hyperaldosteronism (DSH). All three patients became normotensive on dexamethasone treatment alone and have been successfully maintained on low doses of the drug for 6 months since diagnosis. Each of the patients had extremely high plasma and urinary concentrations of the recently discovered steroid 18-hydroxycortisol, which were more than ten times higher than the upper normal limit. Plasma levels were readily suppressed by dexamethasone treatment. The hypothesis that 18-hydroxycortisol might derive from 18-hydroxylation of recirculating cortisol was tested by measuring plasma 18-hydroxycortisol levels during low-dose and high-dose hydrocortisone infusions, in a normal subject and in one of the patients with DSH. During the high-dose infusions (with plasma cortisol levels of 3000-5000 nmol/l) there was net production of 18-hydroxycortisol within 8 h, but this was not observed during the low-dose infusions (plasma cortisol levels 300-400 nmol/l). The origin of 18-hydroxycortisol remains uncertain: these findings do not support the recirculation theory, but lend weight to the alternative hypothesis that 18-hydroxycortisol is produced in transitional adrenocortical tissue. This steroid is of considerable value in the differential diagnosis of primary hyperaldosteronism and may also be important as a marker of transitional adrenal cell function.

Adrenal Cortex↗
PubMed1988

Epstein-Barr virus and human diseases: recent advances in diagnosis.

Since the discovery of Epstein-Barr virus (EBV) from a cultured Burkitt's lymphoma cell line in 1964, the virus has been associated with Burkitt's lymphoma, nasopharyngeal carcinoma, and infectious mononucleosis. During the recent decade, EBV has been etiologically implicated in a broad spectrum of human diseases. The precise role of this virus in these diseases is not well understood, but clearly, defective immunosurveillance against the virus may permit an uncontrolled proliferation of EBV-infected cells. As a result, a growing number of cases of EBV-associated B-cell proliferative diseases or lymphoma have been noted in patients with primary and acquired immunodeficiencies. These lymphoproliferative diseases and others, such as chronic mononucleosis syndrome, are leading to new areas of investigation which are providing information regarding the pathogenetic mechanisms of EBV-induced diseases. The early accurate diagnosis of EBV infection can be achieved by performing EBV-specific serology, detecting for EBV-determined nuclear antigen in tissues, establishing spontaneous lymphoid cell lines, and using molecular hybridization techniques for demonstrating the presence of viral genome in affected lesions.

Burkitt Lymphoma↗
PubMed1988

Calcium dependence of prolactin mRNA accumulation in GH3 rat pituitary tumour cells.

Stimulation of prolactin secretion by TRH probably involves mobilization of intracellular calcium to a greater extent than calcium influx, but less is known about the possible calcium-dependent mechanisms which may control prolactin gene transcription. We have studied this question in the rat pituitary tumour GH3 cell line by measuring prolactin mRNA accumulation by a cytoplasmic dot hybridization assay. Cobalt chloride, an intracellularly acting calcium antagonist, caused marked dose-dependent reductions in prolactin release and mRNA concentrations, whereas the calcium channel-blocking agent verapamil had no effect on prolactin release and had smaller effects on prolactin mRNA. Cobalt chloride abolished the stimulatory effect of TRH on prolactin mRNA levels, while verapamil caused only moderate inhibition. Growth hormone mRNA levels in the same cells were not significantly affected by TRH or verapamil, and only marginally reduced by cobalt. These data suggest that, as for prolactin release from normal rat pituitary lactotrophs, prolactin mRNA accumulation in GH3 cells appears to have a requirement for intracellular calcium which is only partly dependent upon calcium influx.

Calcium↗
PubMed1988

Adenovirus type-2 in a patient with lethal hemorrhagic colonic ulcers and chronic active Epstein-Barr virus infection.

An adenovirus type-2 was isolated from peripheral blood lymphocytes and throat washings from a patient with severe chronic active Epstein-Barr virus infection. Despite the Epstein-Barr virus reactivation, attempts to establish spontaneous lymphoblastoid cell lines from peripheral blood lymphocytes and to immortalize cord lymphocytes with throat washings were unsuccessful due to a marked cytopathic effect. The supernatants from the cultures induced cytopathic effect in cultured cord lymphocytes, MRC-5 cells, A-549 cells, or Vero cells. Virus particles with adenovirus morphology were seen by electron microscopy. Using type-specific antisera, the isolate was identified as adenovirus type-2. In addition, both Epstein-Barr virus and adenovirus type-2 genomes were seen in the colonic tissues and spleen. These results suggest that the combination of Epstein-Barr virus and adenovirus type-2 may be etiologic agents in the development of chronic active Epstein-Barr virus infection in this patient.

Adenoviridae Infections↗
PubMed1988

Analysis of sleep on Shuttle missions.

Many aspects of Shuttle missions may have significant impact on the normal sleeping patterns of crewmembers. Using a standard debriefing form, 58 crewmembers from 9 Shuttle flights (6 single-shift flights, and 3 dual-shift flights) were debriefed within 3 d postflight. Specific questions on the form relating to sleep quality and quantity, fatigue, and sleep medication usage during all flight phases were analyzed. Of crewmembers on dual-shift missions 50% (11 of 22) used sleep medications at least once inflight compared to 19.4% (7 of 36) of single-shift. The biggest impact on normal sleep patterns occurred during the first and last days of a mission, with averages of 5.7 h and 5.6 h, respectively. These results suggest that sleep disruption is a common occurrence on Shuttle missions. Further studies are suggested to develop strategies for coping with this potential problem.

Circadian Rhythm↗
PubMed1988

Space motion sickness during 24 flights of the space shuttle.

The incidence and severity of Space Motion Sickness (SMS) were determined from 24 flights of the Space Shuttle. A standardized questionnaire developed at the NASA-Johnson Space Center (JSC) was administered to all crewmembers postflight during an oral debriefing with the examining flight surgeon. Cases of SMS were graded mild, moderate or severe using criteria developed at the JSC. The incidence of SMS during a first Shuttle flight for 85 crewmembers was 67% (57 cases). There were 26 mild cases (30%), 20 moderate (24%), and 11 severe (13%). Differences were found between males and females, crew positions (Commander, Pilot, Mission Specialist, etc.), and age groups, which were not statistically significant (p greater than 0.05), but would suggest future research into the mechanism, prevention, and treatment of SMS. The 26 crewmembers with a second flight showed a reduction in SMS incidence to 46%, but the change was not significant compared with the first flight. Nine crewmembers (35%) showed a reduction in SMS severity comparing first and second flights, yet there was no significant difference in the mean time between flights for crewmembers with SMS versus asymptomatic crewmembers. Variability in crewmember training and flight experience may explain some of the differences observed.

Adult↗