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Biomedical subjects

P Johnson

Publications and source records attributed to P Johnson.

At least 109 records · Page 6Linked to original sources
PubMed1999

Studies of the 48 bp repeat polymorphism of the DRD4 gene in impulsive, compulsive, addictive behaviors: Tourette syndrome, ADHD, pathological gambling, and substance abuse.

Prior studies have reported an association between the presence of the 7 repeat allele of the 48 bp repeat polymorphism of the third cytoplasmic loop of the dopamine D4 receptor gene (DRD4) and novelty seeking behaviors, attention deficit hyperactivity disorder (ADHD), Tourette syndrome (TS), pathological gambling, and substance abuse. However, other studies have failed to replicate some of these observations. To determine whether we could replicate these associations we genotyped 737 individuals from four different groups of control subjects, and 707 index subjects from four different groups of impulsive, compulsive addictive behaviors including substance abuse, pathological gambling, TS, and ADHD. Chi-square analysis of those carrying the 7 allele versus non-7 allele carriers was not significant for any of the groups using a Bonferroni corrected alpha of.0125. However, chi-square analysis of those carrying any 5 to 8 allele versus noncarriers was significant for pathological gambling (p <.0001), ADHD (p </=.01) and the total index group (p </=.0004). When the comparison included all 7 alleles the results were significant for gamblers (p <.0001), TS (p </=.003), ADHD (p </=.003), and the total group (p </=.0002). There was a significant increase in the frequency of heterozygosity versus homozygosity for all alleles for pathological gamblers (p </=.0031) and the total index group (p </=.0015), suggesting that heterosis played a role. In the substance abuse subjects a quantitative summary variable for the severity of drug dependence, based on the Addiction Severity Index, showed that the scores varied by increasing severity across the following genotypes: 44 </= heterozygotes </= 77 </= 22. Studies of other quantitative traits indicated an important role for the 2 allele and the 22, 24, and 27 genotypes. All studies indicated that the role of the DRD4 gene in impulsive, compulsive, addictive behaviors is more complex than a sole focus on the 7 versus non-7 alleles.

Alleles↗
PubMed1999

The proenkephalin gene (PENK) and opioid dependence.

We tested the hypothesis that the alleles at the (CA)n repeat of the proenkephalin gene (PENK) might be associated with opioid addiction in 31 non-Hispanic Caucasian subjects with opioid dependence (heroin), 89 ethnically matched subjects with substance dependence other than opioid dependence and 132 controls. Among the subjects with opioid dependence, 66% carried the > or = 81 bp allele compared with 40% of subjects with other types of substance abuse (chi2 = 11.31, p < 0.004) and 49% of controls (chi2 = 6.0, p < 0.015). These results are consistent with a role of the PENK gene in opioid dependence.

Adult↗
PubMed1999

Carnosine and taurine protect rat cerebellar granular cells from free radical damage.

Carnosine and taurine have been suggested to protect excitable tissues against oxidative stress. We have investigated the protection of cerebellar granule cells (neurons) by these compounds against free radicals generated by kainic acid (KA), and 3-morpholinosydnonimine hydrochloride (SIN-1) treatment. Carnosine decreased free radical levels in KA and SIN-1 treated cells, and increased cell viability. The KA effect, but not that of SIN-1, was dependent on the presence of external Ca2+ ions. Taurine increased cell viability, but did not decrease free radical levels. These results suggest that there are multiple pathways leading to cell death, not all of which involve decreases in intracellular free radical levels, and also indicate that multiple mechanisms of cellular defense exist against oxidative stress.

Animals↗
PubMed1999

Sources of reactive oxygen species production in excitotoxin- stimulated cerebellar granule cells.

Reactive oxygen species (ROS) production in rat cerebellar granule cells in the presence of the excitotoxins N-methyl-d-aspartate (NMDA) and kainic acid (KA) and by the protein kinase C activator phorbol myristate acetate (PMA) was Ca2+-dependent and resulted in decreased cell viability. Exposure of stimulated cells to rotenone (a respiratory chain inhibitor) did not decrease ROS levels and did not affect short-term cell viability. In cells stimulated by NMDA and KA, exposure to indomethacin (a cyclooxygenase inhibitor) and nialamide (a monoamine oxidase inhibitor) caused a decrease in ROS levels and increased cell viability occurred in NMDA-treated cells. In contrast, PMA-stimulated neurons did not show decreased ROS levels when exposed to indomethacin and nialamide. These studies suggest that there is a multiplicity of routes for Ca2+-dependent ROS production in neurons but that ROS generation by cyclooxygenase and monoamine oxidase is not controlled by protein kinase C.

Animals↗
PubMed1999

Use of hematoxylin stain to enhance evaluation of heart malformations in the fetal rat.

Fresh and formalin-fixed visceral microdissection techniques are valuable tools for studying cardiac teratology in the fetal rat, but are limited by the difficulty experienced in visualizing the minute structures needing to be evaluated. This paper describes a simple and quick staining technique used to enhance the examination procedure. A hematoxylin-saline mixture applied directly on endothelial-lined surfaces of the heart at different stages during microdissection greatly improved visualization of membrane-thin structures such as the pulmonary and aortic semilunar valves, right- and left-side atrioventricular valves, and atrial and ventricular septa. Hematoxylin staining of endocardial surfaces is a useful adjunct to the standard visceral microdissection technique.

Animals↗
PubMed1999

A multi-centre randomized phase II study of nolatrexed versus doxorubicin in treatment of Chinese patients with advanced hepatocellular carcinoma.

PURPOSE: A multi-centre randomized phase II study of single agent nolatrexed dihydrochloride versus doxorubicin was undertaken in Chinese patients with advanced hepatocellular carcinoma (HCC) to study and compare the clinical efficacy of the two drugs. METHODS: Fifty-four patients with clinical or histological diagnosis of HCC were randomized in a 2:1 ratio to receive nolatrexed or doxorubicin. Nolatrexed 725 mg/m(2)/day was given by continuous infusion via a central venous device for 5 days and doxorubicin 60 mg/m(2) was given as a rapid intravenous infusion every 3 weeks. RESULTS: No objective responses were observed in either treatment arm. Two patients in the nolatrexed arm and none in the doxorubicin arm had >50% decline in serum alpha-fetoprotein. The median survival for the patients in the nolatrexed and doxorubicin arms was 139 days and 104 days, respectively. Moderate toxicities including leukopenia, thrombocytopenia, mucositis and skin rash were observed in both treatment arms. CONCLUSION: Nolatrexed and doxorubicin are minimally active in the treatment of advanced HCC. Given the small sample size, no difference is observed between the two drugs.

Adult↗
PubMed1999

The redistributive effect of health care finance in twelve OECD countries.

The OECD countries finance their health care through a mixture of taxes, social insurance contributions, private insurance premiums and out-of-pocket payments. The various payment sources have very different implications for both vertical and horizontal equity and on redistributive effect which is a function of both. This paper presents results on the income redistribution consequences of the health care financing mixes adopted in twelve OECD countries by decomposing the overall income redistributive effect into a progressivity, horizontal inequity and reranking component. The general finding of this study is that the vertical effect is much more important than horizontal inequity and reranking in determining the overall redistributive effect but that their relative importance varies by source of payment. Public finance sources tend to have small positive redistributive effects and less differential treatment while private financing sources generally have (larger) negative redistributive effects which are to a substantial degree caused by differential treatment.

Cross-Cultural Comparison↗
PubMed1999

Equity in the finance of health care: some further international comparisons.

This paper presents further international comparisons of progressivity of health care financing systems. The paper builds on the work of Wagstaff et al. [Wagstaff, A., van Doorslaer E., et al., 1992. Equity in the finance of health care: some international comparisons, Journal of Health Economics 11, pp. 361-387] but extends it in a number of directions: we modify the methodology used there and achieve a higher degree of cross-country comparability in variable definitions; we update and extend the cross-section of countries; and we present evidence on trends in financing mixes and progressivity.

Cross-Cultural Comparison↗
PubMed1999

Antihypertensive drug therapy and antioxidant enzyme mRNA levels in spontaneously hypertensive (SHR) rats.

Previous studies have shown that chronic treatment of SHR (spontaneously hypertensive) rats with the antihypertensive drugs captopril, hydralazine and terazosin results in changes in the specific activities of the antioxidant enzymes glutathione peroxidase, catalase and Cu/Zn superoxide dismutase in liver and myocardium. In order to determine if these changes were caused by alterations in the levels of the mRNAs for these enzymes, the tissue levels of the antioxidant enzyme mRNAs have been measured. In myocardium, all three drug treatments increased Cu/Zn superoxide dismutase mRNA but decreased glutathione peroxidase mRNA levels, and in liver, all three drugs changed glutathione peroxidase mRNA levels. In comparison to untreated SHR animals, the levels of all three mRNAs were altered in the myocardium, but not in the liver, of normotensive WKY rats. Comparisons of mRNA levels with tissue enzyme specific activities suggest that tissue antioxidant enzyme expression is, in most cases, regulated by antihypertensive drugs through transcriptional control mechanisms.

Animals↗
PubMed1999

Ethanol has differential effects on rat neuron and thymocyte reactive oxygen species levels and cell viability.

In rat thymocytes and cerebellar granule cells, reactive oxygen species (ROS) levels were increased and cell viability was decreased as a result of exposure to ethanol (up to 0.4%). Thymocytes showed larger increases in ROS levels, but neurons showed more pronounced decreases in cell viability. These parameters in neurons were relatively unaffected when the cells were incubated with ethanol in the presence of inhibitors of alcohol-oxidizing enzymes, but in thymocytes, the presence of diallyl sulfide (an inhibitor of alcohol-inducible cytochrome P450, CYP2E1) or 4-methylpyrazole (an inhibitor of CYP2E1 and alcohol dehydrogenase) caused decreases in ROS production from ethanol. In both cell types, the presence of 3-aminotriazole (an inhibitor of catalase) did not decrease ROS production from ethanol. These studies show that the cytotoxic effects of ethanol in neurons may not be the result of oxidative metabolism of ethanol, whereas in thymocytes, the cytotoxic effect of ethanol is principally a result of its oxidative metabolism.

Alcohol Dehydrogenase↗
PubMed1999

Rural people's experience of critical illness involving inter-hospital transportation: a qualitative study.

In recent years there has been a growing awareness of the problems people living in rural areas of Australia face in accessing health-care services. In particular, those experiencing a critical illness or major trauma and requiring specialist critical care services, often available only in metropolitan areas, may require inter-hospital transportation, usually by air ambulance. Management of such patients aims at achieving physiological stabilisation, organising the transfer and communicating with the transport team. As critical care nurses espouse a holistic approach to care, it is imperative that nursing practice aim to meet all the needs of these people. Therefore, critical care nurses should be aware of what such patients are experiencing. A qualitative research study, using Heideggerian hermeneutic phenomenology, was undertaken to explore the experiences of a group of people from rural NSW with a critical illness that necessitated their transfer by air ambulance to a metropolitan critical care unit for further management. Data analysis from interviews with the study participants revealed four major themes. This paper discusses the findings from one such theme, the impact of interhospital transportation, and highlights the anxiety and confusion experienced by rural people transferred to a metropolitan critical care unit. Recommendations for nursing care that minimises this anxiety and confusion are discussed.

Adult↗
PubMed1999

Potential role of the estrogen receptor gene (ESR1) in anxiety.

In addition to neurotransmitters, hormones, acting through the blood stream, also play a role in behavior. To test the potential contribution of genetic variations in hormone receptors we have examined the association between the alleles of the dinucleotide repeat of the estrogen receptor 1 gene (ESR1) and the nine subscores and total score of the SCL-90 in a group of 179 adult males treated for substance abuse. Based on our prior hypothesis that the length of repeat polymorphisms may play a direct role in gene regulation, the alleles were divided into two groups, short (S) and long (L). ANOVA of the SS, LS, and LL genotypes showed a significant association at alpha </=0.05 for three of the SCL-90 scores: anxiety, phobic anxiety, and total symptoms. Of these the anxiety score remained significant at a Bonferroni corrected alpha of </=0.005. By regression analysis, the ESR1 gene accounted for 7% of the variance of the anxiety score (P </= 0.0004). These results are consistent with a role of the ESR1gene in human behavior. Since estrogen levels are much higher in women than men, this could account for the increased frequency of anxiety in women.

Adult↗