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Biomedical subjects

J Becker

Publications and source records attributed to J Becker.

At least 217 records · Page 12Linked to original sources
PubMed1989

Alpha 1-adrenergic stimulation causes Mg2+ release from perfused rat liver.

The possibility that Mg2+ mobilization is stimulated in perfused liver by alpha 1-adrenergic agonists was studied by measuring Mg2+ release in response to 0.5 and 20 microM phenylephrine. During preperfusion exogenous Mg2+ was added to the medium to give 1.2 mM. 5 min before starting the addition of phenylephrine the infusion of exogenous Mg2+ was stopped. Mg2+ in the perfusate leaving the liver was measured by atomic absorption spectroscopy. Analysis of the Mg2+ decay curves with two exponential models indicated that phenylephrine caused dose-dependent Mg2+ release from perfused rat livers.

Animals↗
PubMed1989

Melanotic neuroectodermal tumor of infancy: report of two cases.

Melanotic neuroectodermal tumor of childhood is a rare lesion, but its presentation appears to be quite characteristic and a clinical diagnosis may be made with some confidence. Although this is an extremely rapidly growing, aggressive tumor, local excision appears to be adequate for cure.

Dentigerous Cyst↗
PubMed1989

The effect of subliminal oedipal and competitive stimulation on dart throwing: another miss.

Silverman and his associates have reported that subliminal presentation of oedipally relevant competitive stimuli can modify dart-throwing performance in male subjects. This study replicated their paradigm, but also examined the effects on performance of nonoedipal competitive stimuli. Our results failed to support Silverman's. Both types of subliminally presented competitive stimuli failed to have any systematic effect on dart-throwing performance.

Adolescent↗
PubMed1989

Acute radiodermatitis from occupational exposure to iridium 192.

Industrial radiography using the man-made radioisotope iridium 129 is commonplace in the southern states. Despite established procedures and safeguards, accidental exposure may result in typical acute radiodermatitis. We have presented a clinical example of this phenomenon.

Acute Disease↗
PubMed1989

Oral hairy leukoplakia: observations in 95 cases and review of the literature.

Oral hairy leukoplakia (HL) was observed in 25.4% of 373 HIV-seropositive patients (n = 95). 87 were men of an average age of 37.1 yr, 8 were women (30.3 yr). 71.6% of the patients were male homosexuals. At initial diagnosis of HL the majority of cases was classified as CDC IVc1 (45.3%) and CDC II (22.1%). Average CD4/CD8 ratio (n = 19) was 0.24 with a range of 0.04-1.0. Thirty biopsies of HL revealed some of the histologic features thought to be characteristic. In only 20 of 30 biopsies EB-virus-specific-capsid antigen was detected. The problems of clinical and histological diagnosis of HL are discussed. Further strict criteria are necessary in order to define HL more distinctly.

Adult↗
PubMed1989

Yeast Hsp70 RNA levels vary in response to the physiological status of the cell.

Yeast Hsp70 genes constitute a multigene family in which at least five of the nine members are heat inducible. Hsp70 RNA levels also vary dramatically during stationary arrest and sporulation. During growth to stationary phase, SSB1-SSB2 and SSC1 RNAs decreased in abundance as cell density increased. In contrast, SSA1-SSA2 RNA levels increased before the diauxic shift and then decreased as cells approach stationary phase. SSA3 RNA was detected only after the diauxic shift and accumulated to high levels as cells entered stationary phase. This accumulation was reversed by addition of glucose. Studies with cyr1 mutants indicated that SSA3 RNA accumulation is stimulated by decreasing intracellular cyclic AMP concentrations. When cells were incubated in sporulation medium, most Hsp70 RNAs, with the exception of SSA1-SSA2 RNA, decreased in abundance. This finding contrasted with the SSA1-SSA2 pattern observed during growth to stationary phase. SSA3 RNA was not detected during growth in acetate-based medium but accumulated after several hours. SSA3 RNA accumulation was higher in sporulating cells than in nonsporulating cells and was reversed by addition of glucose.

Electrophoresis, Gel, Two-Dimensional↗
PubMed1989

Changes in plasma epinephrine concentration after dental infiltration anesthesia with different doses of epinephrine.

To define the cardiovascular risk as a result of epinephrine in local anesthetic solutions used in dental anesthesia, we measured the plasma epinephrine levels, the mean arterial brachial pressure (MAP), and heart rate for 15 min, after infiltration anesthesia in the area buccal to the upper permanent left lateral incisor and canine. For this purpose, 12 dental student volunteers received 2.0 mL 2% lidocaine with and without 20 or 80 micrograms epinephrine, in a double-blind cross-over trial. --Plain lidocaine solution cause no significant changes in the parameters under study when compared with the baseline values. --Lidocaine with 20 micrograms epinephrine caused a sustained doubling of the plasma epinephrine concentration two min after injection, and at the same time, a slight but significant (p less than 0.05) decrease in MAP. Two min and 45 s after injection, the heart rate increased by four beats/min when compared with the baseline rate. --Lidocaine with 80 micrograms epinephrine caused a doubling of the basal plasma epinephrine value as early as one min and 25 s after injection, and a ten-fold increase above the basal value at the end of the observation period (15 min). The heart rate increased significantly (p less than 0.01) by five beats/min above the baseline value starting two min after injection, and rose to a maximum of 13 beats/min until the end of the observation period. The time-point of the decrease in MAP was earlier, but the amount of the decrease equaled that measured after submucosal injection of 20 micrograms epinephrine with 40 mg lidocaine.

Adult↗
PubMed1989

To be or not to be: the suicidal patient.

Depression is a common condition in the practice of most physicians. Some depressed patients are prone to suicide, many ambivalent about it. The SAD PERSONS scale may be helpful for the physician in assessing risk. Because of the ambivalence, it is important that an authority figure-physician, friend, family member- not fail to recognize the risk and unthinkingly sanction a destructive act.

Adult↗
PubMed1989

Preschoolers' use of number words to denote one-to-one correspondence.

Preschoolers' use of number words to denote one-to-one correspondence was assessed by 2 tasks. In the matching task, the children matched 2 sets to determine whether they could be put in one-to-one correspondence and then judged whether the same number word should be used to denote both sets. In the counting task, the children counted 2 sets and used the final number words of the count to determine whether the sets could be put in one-to-one correspondence. Most 4-year-olds and some 3 1/2-year-olds use number words to denote one-to-one correspondence in each of these tasks. These findings are related to previous research.

Child, Preschool↗
PubMed1988

Primary structure and functional organization of Drosophila 1731 retrotransposon.

We have determined the nucleotide sequence of the Drosophila retrotransposon 1731. 1731 is 4648 bp long and is flanked by 336 bp terminal repeats (LTRs) previously described as being reminiscent of provirus LTRs. The 1731 genome consists of two long open reading frames (ORFs 1 and 2) which slightly overlap each other. The ORF 1 and 2 present similarities with retroviral gag and pol genes respectively as shown by computer analysis. The pol gene exhibits several enzymatic activities in the following order: protease, endonuclease and reverse transcriptase. It is possible that 1731 also encompasses a ribonuclease H activity located between the endonuclease and reverse transcriptase domains. Moreover, comparison of the 1731 pol gene with the pol region of copia shows similarities extending over the protease, endonuclease and reverse transcriptase domains. We show that codon usage in the two retrotransposons is different. Finally, no ORF able to encode an env gene is detected in 1731.

Animals↗
PubMed1988

Hydrogen peroxide (H2O2) induces actin and some heat-shock proteins in Drosophila cells.

Drosophila cells of a clone derived from line Kc were treated with various concentrations of hydrogen peroxide (H2O2). The concentration of 10 mM was lethal, whereas concentrations of 1-100 microM did not affect cell viability, rate of multiplication or protein synthesis. The intermediate concentration of 1 mM H2O2 was used to study the response of the cells to an oxidative stress. We observed a transitory decrease of the global protein synthesis, which was accompanied by changes in the polypeptide pattern. There was a 2.5-fold increase of the synthesis of the heat-shock proteins 70-68 and 23. The most prominent response was a 6.5-fold increase of actin synthesis 3 h after a 1 mM H2O2 treatment. When aminotriazole (an inhibitor of catalase) was added in association with H2O2, the increase of actin synthesis became 8.5-fold. Experiments in which catalase was added at various times after H2O2 showed that a 10-min treatment with H2O2 was sufficient to induce actin and heat-shock protein synthesis 3 h later. H2O2 was shown to induce the transcriptional activation of an actin gene and of the heat-shock protein genes 70 and 23 within minutes. These results are coherent with the hypothesis that the byproducts of O2 reduction (the superoxide ion and hydrogen peroxide) could be inducers of the heat-shock response. Whether the increase of actin synthesis is a stress-related response, and the mode of action of H2O2 are discussed.

Actin Cytoskeleton↗
PubMed1988

Immunohistochemical detection of HIV structural proteins and distribution of T-lymphocytes and Langerhans cells in the oral mucosa of HIV infected patients.

Seventeen biopsies taken from oral mucosa of HIV infected patients were analysed for the distribution of CD4+/CD8+ T-lymphocytes and Langerhans cells. The results were evaluated statistically. An increase in the absolute number of CD4+ and CD8+ cells in HIV infected patients without clinical symptoms, ARC or AIDS was seen in the connective tissue stroma when compared with normal oral mucosa from sero-negative patients. However, the ratio between CD4+/CD8+ cells was decreased due to the disproportionate increase of CD8+ cells. These findings did not show statistical correlation with the clinical status of the infection. In contrast to the increase in absolute number of CD4+/CD8+ cells the number of Langerhans cells was unchanged when compared with the control group. Using four different monoclonal antibodies against virus structural proteins (2 X anti p24, gp41, gp120) two of 26 patients showed labelled cells in consecutive sections in the same connective tissue areas. It was assumed that latently infected mononuclear cells invaded the oral mucosa together with uninfected cells of the cellular immune system.

AIDS-Related Complex↗
PubMed1988

Ultrastructural and immunohistochemical findings in oral hairy leukoplakia.

Three cases of HL from the lateral border of the tongue of male homosexual AIDS patients were investigated by thin section electron microscopy. Keratinocytes contained condensed chromatin in their pyknotic nuclei and a few organelles in the oedematous cytoplasm. Chromatin was in close association to the nuclear membrane and showed a punched-out appearance. Particles typical of the herpes virus group were abundant in the upper two thirds of the epithelium in all three cases. Virus particles were seen frequently in the nuclei of the ballooned keratinocytes, but rarely in cells containing Candida albicans. Viral nucleocapsids were observed budding at the inner nuclear membrane, thereby acquiring the prospective viral envelope. Complete, enveloped virions were found in the endoplasmic reticulum and in the extracellular space. These virions were identified immunohistochemically as Epstein-Barr virus (EBV) using two monoclonal antibodies directed against EBV capsid and membrane antigen, respectively. Candida albicans was observed in the stratum corneum and in the upper layer of the stratum spinosum. Special cytoplasmic tubular structures arranged in parallel bundles were found in koilocytotic cells in addition to characteristic membrane structures composed of undulating convoluted membranes. Epithelial basement membranes were always intact.

Acquired Immunodeficiency Syndrome↗