Absence of mutations in superoxide dismutase and catalase genes in patients with Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) is an adult-onset, neurodegenerative disorder characterized by a selective loss of the dopaminergic cells of the substantia nigra and by progressive motor decline. Studies have shown aberrant oxidative stress metabolism within the substantia nigra and other dopaminergic regions of the brain in patients with PD. OBJECTIVE: To screen the genes of three free radical detoxifying enzymes--copper/zinc superoxide dismutase, manganese superoxide dismutase, and catalase--for mutations in patients with PD. PATIENTS AND METHODS: A total of 107 unrelated patients with PD from two PD populations (familial and sporadic) were screened for mutations in the genes of copper/zinc superoxide dismutase, manganese superoxide dismutase, and catalase by single-strand conformation analysis. The diagnosis of PD was based on the clinical observations of resting tremor, rigidity, and bradykinesia. RESULTS: No mutations were identified. However, we did identify an amino acid substitution (glycine to aspartic acid) in exon 9 of the catalase gene in one patient; decreased red blood cell catalase activity was observed in this patient. CONCLUSION: Parkinson's disease is not caused by mutations in the genes of these three detoxifying enzymes. The exon 9 variant in the catalase gene in the one family with PD is most likely a silent mutation and not the genetic cause of PD in this family.

Ethanol metabolism in rat brain homogenates by a catalase-H2O2 system.

Homogenates of perfused rat brains incubated in the presence of ethanol (50-100 mM) and glucose (10 mM) were found to oxidize ethanol to acetaldehyde. The addition of glucose oxidase, a known hydrogen peroxide generator, to the incubation medium, significantly (P less than 0.05) increased the generation of acetaldehyde. The presence in the incubation medium of metyrapone, an inhibitor of cytochrome P450, or pyrazole, an alcohol dehydrogenase inhibitor, did not affect the levels of acetaldehyde obtained. Conversely, the presence of 3-amino-1,2,4-triazole, a known catalase inhibitor, induced a concentration-dependent reduction of the amount of acetaldehyde generated after incubation, even in the presence of glucose oxidase. Homogenates of perfused brains of rats treated with 3-amino-1,2,4-triazole or cyanamide (another H2O2-dependent catalase blocker) also showed a dose-dependent reduction of the acetaldehyde obtained. These findings support the notion that a catalase-mediated oxidation of ethanol is present in rat brain homogenates. It is suggested that this local oxidation of ethanol may have important biological implications. The data of both studies increase support for the notion that acetaldehyde is produced directly in the brain and that it may be the agent mediating some of the psychopharmacological properties of ethanol and be one of the factors determining the propensity of an animal to voluntarily consume ethanol.

Dose- and time-dependent effect of an acute 3-amino-1,2,4-triazole injection on rat brain catalase activity.

The results presented in this study demonstrate a progressive inhibition of rat brain catalase activity by AT in vivo. Furthermore, the inhibition of brain catalase by AT demonstrates the presence of hydrogen peroxide in brain, since AT inhibits catalase in the presence of this compound. The rate of inhibition of catalase seems to be dependent upon the rate by which H2O2 is generated. A time course study showed slower onset of the inhibition of brain as compared to liver catalase, possibly reflecting tissue hydrogen peroxide levels or, alternatively, a rate-limiting penetration of AT into brain and into the catalase compartment. The presence of AT in brain was confirmed over the time period of the observed inhibition of brain catalase. Catalase inhibitors are of particular interest in the study of the physiological role of catalase. This study further supports the use of AT in investigations designed to further understand the role of brain catalase.

The nitric oxide synthase inhibitor NW-nitro-L-arginine methylester attenuates brain catalase activity in vitro.

Nitric oxide has been implicated in mediating the neurotoxic effects of ischemia in the brain. However, studies of the effects of nitric oxide inhibition with nitric oxide synthase inhibitors have provided controversial results. One of the reasons for the controversy may be related to the specificity of the nitric oxide synthase inhibitors, such as Nw-nitro-L-arginine methylester (L-NAME), which has recently been questioned. The present work investigated the possible interaction of L-NAME with the enzyme catalase in vitro. Catalase is an iron containing enzyme which could potentially interact with the iron-binding groups of L-NAME. Since the normal function of catalase in the brain is to remove excess hydrogen peroxide, the inhibition of this process could have potentially toxic effects. L-NAME was found to attenuate the catalase inhibiting effects of the known catalase inhibitor cyanamide in vitro, suggesting a competition between cyanamide and L-NAME for catalase. In addition, L-NAME by itself attenuated catalase activity in vitro. These results indicate that in addition to inhibiting nitric oxide synthase, L-NAME may have effects on catalase activity.

Caffeine promotes ethanol drinking in rats. Examination using a limited-access free choice paradigm.

There is growing evidence that caffeine may alter the pattern of intake of a variety of drugs. The present study was designed to assess the effect of caffeine pretreatment on voluntary ethanol consumption. The first experiment examined the effect of caffeine on the acquisition of ethanol intake in a limited-access-choice procedure in which water and ethanol were presented concurrently. Male Wistar rats, exposed to food and water ad lib, were presented with a daily 1-h choice session between water and progressively increasing concentrations of ethanol (2-10%). Each ethanol concentration was made available for 4-6 days for a total of 20 days of access to ethanol. Intraperitoneal injections of caffeine (5 or 10 mg/kg) or saline were administered to the rats 30 min prior to each choice session. Caffeine produced a dose-related facilitation in ethanol drinking whereby the lower caffeine dose produced enhancement in ethanol drinking. The second experiment examined the effect of caffeine on the maintenance of established ethanol consumption. Male Wistar rats, initially acclimatized to increasing concentrations of ethanol (2%-10), were presented with an additional 18 ethanol (10%) presentations, comprised of a 6-day baseline period followed by 6 days of treatment where animals were given one of three doses of caffeine (2.5, 5 or 10 mg/kg) or saline prior to ethanol presentation. A final 6-day post-treatment period followed treatment. These results revealed an inverted-U effect of caffeine dose on ethanol ingestion where the low and high caffeine doses produced no effect but the moderate dose of 5 mg/kg enhanced ethanol drinking that persisted throughout the post-treatment period. A third experiment revealed that caffeine did not alter levels of blood ethanol within the time period used for the ethanol drinking session.

Augmentation of corticosterone release by means of a caffeine-ethanol interaction in rats.

We examined whether the acute treatment with caffeine delivered before an ethanol injection would augment plasma corticosterone (CORT) levels. The effect of caffeine on blood ethanol levels was also assessed. After 10 days of acclimatization to the colony room conditions, male Wistar rats were injected with either caffeine (5 mg/kg, ip) or saline 30 min before the delivery of ethanol (0.8 g/kg, ip) or saline, respectively. Trunk blood was then collected at 15 and 30 min after the ethanol injection for determination of plasma CORT and blood ethanol levels. CORT was measured with the use of radioimmunoassay, and blood ethanol levels were determined with the use of gas chromatography. The results showed that although caffeine and ethanol delivered singly failed to augment plasma CORT levels, the combination of both drugs produced elevations in plasma CORT levels at 15 and 30 min. These findings were found to be unrelated to changes in ethanol metabolism as caffeine failed to alter blood ethanol levels within the period tested. It was argued that the present elevations in plasma CORT levels observed in animals administered caffeine and ethanol may play a role in the caffeine-induced elevations in ethanol drinking observed elsewhere.

Caffeine promotes an ethanol-induced conditioned taste aversion: a dose-dependent interaction.

The present study examined whether caffeine administered within a dose range previously shown to promote ethanol drinking would also alter an ethanol-induced conditioned taste aversion (CTA). The results revealed a dose-dependent interaction between caffeine and ethanol where caffeine (2.5 and 10 mg/kg) promoted an ethanol-induced CTA at a low ethanol dose (1.0 g/kg) but had no effect in blocking CTA at the higher ethanol dose (1.5 g/kg). These results were found to be unrelated to an alteration in ethanol metabolism, as caffeine had no effect in altering blood ethanol levels at the doses tested. In agreement with the reward comparison hypothesis, the present results suggest that rather than attenuate ethanol's "aversive" effects, caffeine may have promoted an ethanol-induced CTA by increasing the reinforcing efficacy of ethanol.

Changes in brain dopamine levels, oocyte growth and spermatogenesis in rainbow trout, Oncorhynchus mykiss, following sublethal cyanide exposure.

Whole brain dopamine (DA) and norepinephrine (NE) levels were measured in sexually maturing (2 years +) male and female rainbow trout, Oncorhynchus mykiss, following exposure to 0.01 mg/L hydrogen cyanide (HCN). Following a 12 day exposure period in July and August 1988, whole brain DA levels of HCN exposed fish were significantly higher (p less than 0.05), relative to control fish, as measured by high performance liquid chromatography (HPLC). Brain NE levels were unaffected by HCN exposure. Whole brain DA and NE levels showed a strong correlation in control fish (r = +0.81), but not in HCN exposed fish (r = +0.28), likely due to altered DA levels in the latter group. No significant differences were found in brain DA and NE levels between males and females. Mean diameters of oocyte from ovaries of the vitellogenic females were significantly (p less than 0.01) reduced from 226 to 183 microns in control and HCN exposed fish respectively. Testes from males revealed significantly (p less than 0.001) higher numbers of spermatogonial cysts in HCN exposed fish. Evidence is given that chronic exposure to sublethal levels of HCN significantly alters brain DA levels in both sexes of rainbow trout, reduces growth in vitellogenic oocytes of the ovary in females and interferes with the passage of spermatogonia to the spermatocyte stage in sexually maturing males. Collectively, these results suggest that sublethal HCN affects the reproductive mechanisms via the hypophyseal-gonad axis in sexually maturing rainbow trout.

Corticosterone response to an acute dose of ethanol in naive and ethanol experienced rats.

The corticosterone response to an acute dose of ethanol (2 g/Kg, i.p.) was measured in the same rats in three different occasions: prior to, immediately following exposure to ethanol in a free choice self-administration paradigm and after a 15 day period of abstinence following exposure. Corticosterone was measured fluorometrically from tail blood samples collected 30 minutes following the ethanol injection. Blood ethanol levels were determined by gas chromatography. Mean plasma corticosterone and ethanol levels following the acute ethanol challenge were not significantly different in the three tested periods. A significant negative correlation between plasma corticosterone levels in the naive state and subsequent levels of individual voluntary ethanol intake was obtained. No apparent relationship was observed, however, between the same levels of ethanol consumption and the corticosterone response in these animals after ethanol exposure or exposure with abstinence. These data suggest that levels of ethanol intake may be related to the initial response to acute ethanol of the adrenal-pituitary axis. If so, this acute response to ethanol may be used to predict subsequent levels of ethanol intake.

Economic costs of cataract surgery using a rigid and a foldable intraocular lens.

Optimal delivery of healthcare requires consideration of various costs. A foldable intraocular lens (IOL) is more expensive than an equivalent rigid IOL. However, surgical and post-operative costs may make a foldable IOL economically preferable. We compared the economic costs of cataract surgery plus implantation of a foldable IOL with implantation of a rigid IOL. Prospective audit of the clinical records of 82 pseudophakes; 39 implanted with a rigid IOL and 43 implanted with a foldable IOL by one surgeon. Average follow-up periods were 25 +/- 7 months and 23 +/- 5 months respectively. There was no difference between the two groups for the follow-up period (P = 0.55), number of post-operative complications (P = 0.25) or cost of post-operative visits (P = 0.83). The cost of single-use theatre equipment was greater for the rigid-IOL group (P= 0.0001). The total identified cost per patient was greater for the foldable-IOL group (P = 0.0001). Despite possible technical advantages, implantation of the foldable IOL did not provide an economic benefit, either in the initial cost or in the costs of post-operative care. Over the 2-year period, implanting with the rigid IOL cost, on average, Pound Sterling57 less per patient. Despite this economic difference, a cost-benefit analysis is required, since other factors may be more important.

"Becoming a mother'--developing a new theory of early motherhood.

This paper explains the methods used in a grounded theory analysis of the experience of 55 first-time mothers in Australia, presented in the first of this series of two papers. The categories identified in the research are realising, readiness, drained, aloneness, loss and working it out, encompassed in the core category becoming a mother. Specifically, this paper extends the analysis and explains the application of a 'paradigm model' and the identification of a Basic Social Process (BSP). The paper links the analysis to the literature on early motherhood from nursing, midwifery, feminist, and sociological research. A substantive theory is proposed to explain women's experience in becoming mothers that demonstrates how, when responsive to the needs of those researched, a grounded theory analysis can provide a framework for nursing and midwifery care.

Becoming a mother--an analysis of women's experience of early motherhood.

This paper presents the results of a qualitative study conducted by midwife researchers into women's experience of new motherhood. Data were collected using focus groups involving 55 first-time mothers and analysed using grounded theory method. The analysis produced six categories: 'realizing', 'unready', 'drained', 'aloneness', 'loss' and 'working it out'. The core category, 'becoming a mother', integrates all other categories and encapsulates the process of change experienced by women. Also explained are factors mediating the often distressing experience of becoming a mother. The analysis provides a conceptualization of early motherhood enabling the development of strategies for midwives, nurses and other helping women negotiate this challenge.