Lanosterol induces mitochondrial uncoupling and protects dopaminergic neurons from cell death in a model for Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder marked by the selective degeneration of dopaminergic neurons in the nigrostriatal pathway. Several lines of evidence indicate that mitochondrial dysfunction contributes to its etiology. Other studies have suggested that alterations in sterol homeostasis correlate with increased risk for PD. Whether these observations are functionally related is, however, unknown. In this study, we used a toxin-induced mouse model of PD and measured levels of nine sterol intermediates. We found that lanosterol is significantly (∼50%) and specifically reduced in the nigrostriatal regions of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mice, indicative of altered lanosterol metabolism during PD pathogenesis. Remarkably, exogenous addition of lanosterol rescued dopaminergic neurons from 1-methyl-4-phenylpyridinium (MPP+)-induced cell death in culture. Furthermore, we observed a marked redistribution of lanosterol synthase from the endoplasmic reticulum to mitochondria in dopaminergic neurons exposed to MPP+, suggesting that lanosterol might exert its survival effect by regulating mitochondrial function. Consistent with this model, we find that lanosterol induces mild depolarization of mitochondria and promotes autophagy. Collectively, our results highlight a novel sterol-based neuroprotective mechanism with direct relevance to PD.

Increased expression of acyl-coenzyme A: cholesterol acyltransferase-1 and elevated cholesteryl esters in the hippocampus after excitotoxic injury.

Significant increases in levels of cholesterol and cholesterol oxidation products are detected in the hippocampus undergoing degeneration after excitotoxicity induced by the potent glutamate analog, kainate (KA), but until now, it is unclear whether the cholesterol is in the free or esterified form. The present study was carried out to examine the expression of the enzyme involved in cholesteryl ester biosynthesis, acyl-coenzyme A: cholesterol acyltransferase (ACAT) and cholesteryl esters after KA excitotoxicity. A 1000-fold greater basal mRNA level of ACAT1 than ACAT2 was detected in the normal brain. ACAT1 mRNA and protein were upregulated in the hippocampus at 1 and 2 weeks after KA injections, at a time of glial reaction. Immunohistochemistry showed ACAT1 labeling of oligodendrocytes in the white matter and axon terminals in hippocampal CA fields of normal rats, and loss of staining in neurons but increased immunoreactivity of oligodendrocytes, in areas affected by KA. Gas chromatography-mass spectrometry analyses confirmed previous observations of a marked increase in level of total cholesterol and cholesterol oxidation products, whilst nuclear magnetic resonance spectroscopy showed significant increases in cholesteryl ester species in the degenerating hippocampus. Upregulation of ACAT1 expression was detected in OLN93 oligodendrocytes after KA treatment, and increased expression was prevented by an antioxidant or free radical scavenger in vitro. This suggests that ACAT1 expression may be induced by oxidative stress. Together, our results show elevated ACAT1 expression and increased cholesteryl esters after KA excitotoxicity. Further studies are necessary to determine a possible role of ACAT1 in acute and chronic neurodegenerative diseases.

The effect of APOE genotype on brain levels of oxysterols in young and old human APOE epsilon2, epsilon3 and epsilon4 knock-in mice.

Despite apolipoprotein E's important role in cholesterol transport and metabolism in the brain as well as its influence on Alzheimer's disease, the impact of the human APOE genotype on cholesterol metabolism in brain has not been fully examined. This study was carried out to investigate APOE genotype effects on oxysterols measured. In this study the measurement of cholesterol and several oxysterols in the brains of human APOE epsilon2, epsilon3 and epsilon4 knock-in mice at 8 weeks and 1 year of age using gas chromatography mass spectrometry (GC-MS) demonstrated no APOE genotype or age effect on total brain cholesterol and the oxysterol 24-hydroxycholesterol. The level of 27-hydroxycholesterol was elevated in 1 year old animals for all APOE genotypes. Interestingly, lathosterol an indicator of cholesterol synthesis was significantly reduced in the 1 year old animals for all APOE genotypes. APOE epsilon4 expressing mice exhibited statistically lower levels of lathosterol compared to APOE epsilon2 in both the young and old mice. Oxidized cholesterol metabolites were significantly lower in APOE epsilon2 mice compared to other genotypes at 8 weeks old. Although minimal differences were observed between APOE E3 and E4 knock-in (KI) mice, these findings indicate that there are some clear APOE genotype specific effects on brain cholesterol synthesis and associated metabolic pathways, particularly in APOE epsilon2 KI mice.

Better informed: an overview of health informatics.

Healthcare informatics is increasing in importance both for healthcare administrators and medical and dental practitioners. Governments across the developed world are initiating major national health IT programmes. At the same time, future best medical and dental practice will increasingly depend on computer-based support tools, although disagreement remains about the effectiveness of current support tools. Over the longer term, future informatics tools, combined with other medical and dental technology modalities, promise more adaptive, patient-focused and efficient healthcare and education for the practitioner and the patient.

The personal dental service as a setting for an undergraduate clinical programme.

OBJECTIVE: To investigate the feasibility and benefits of placing dental undergraduates into a general dental practice setting for part of their clinical programme. SETTING: Two six-surgery general dental practices in the North West of England operating within the personal dental service of the NHS. METHOD: Six volunteer final year students worked within the practices for one-day-per week for 11 weeks. Evaluation included patients', practitioners' and students' views obtained from questionnaires and/or interviews and an analysis of students' clinical records. RESULTS: The students saw a large positive impact from: working alongside a dental nurse; developing their clinical skills; working in a busy practice environment; and developing interpersonal skills. Patients were very positive with 98% (44/45) being complimentary about the treatment they received, and commenting that they would be willing to participate in future student training programmes. The practice principals would also welcome continuation of the programme. CONCLUSION: The programme was both feasible and educationally beneficial. The financial implications need further research.

A clinical minimum data set for primary dental care.

OBJECTIVE: To achieve consensus within primary dental care on the contents of a clinical minimum data set to measure oral health status. DESIGN: Using the Delphi process a simple random sample of 30 LDCs and 10 CDS services in England were asked to rank a list of existing clinical indicators in order of their perceived importance as a means of measuring oral health. A nominated panel representing the stakeholder organisations of primary dental care reviewed this ranking and identified a core group of clinical indicators to be included in a clinical minimum data set. RESULTS: An 80 percent response rate to the Delphi process was achieved. Consensus was reached on a core group of 10 indicators, which can provide information on patient's perceptions of pain, function and appearance, and professional measurements of caries, teeth present, periodontal disease, oral sepsis, presence of mucosal pathology and tooth wear. CONCLUSIONS: A representative sample of primary care dentists in England and the key representative organisations of primary dental care achieved consensus on the contents of a clinical minimum data set to record oral health status in primary dental care. This is a first step in standardising the measurement of oral health status across primary care.

In vitro microsomal metabolism of hydrazine.

1. It has been demonstrated that hydrazine is metabolized by rat liver enzymes located in the microsomal fraction. This metabolism was reduced in the absence of oxygen or NADPH and was increased by NADH in the presence of NADPH. 2. Microsomal enzyme inhibitors, piperonyl butoxide and metyrapone, significantly inhibited hydrazine metabolism but glutathione had no affect and was not depleted. 3. In addition to P450, flavin monooxygenase may also be involved in catalysing the microsomal metabolism of hydrazine. 4. Liver microsomes prepared from either beta-naphthoflavone, acetone or the isoniazid-pretreated rat did not show a significant increase in hydrazine metabolism compared with microsomes from the control rat. However, although phenobarbitone pretreatment increased overall microsomal hydrazine metabolism this was not increased relative to P450 content. 5. Hydrazine metabolism was 20-70% lower in human microsomes prepared from three individuals compared with the control rat. 6. Hydrazine is also metabolized by rat liver mitochondria but the monoamine oxidase inhibitors clorgyline and pargyline do not significantly decrease this.

The views and expectations regarding dental care of the parents of children with special dental needs: a survey in the County of Cheshire, England.

A postal questionnaire of multiple-choice design was sent to 122 parents of children with special dental needs in the county of Cheshire, England, with the aim of determining parents' views and expectations of dental care. Replies were received from 85 (70%). Eighty respondents (94%) were in favour of preventive dental advice being given to their children and 83 (98%) felt that an explanation should be given of the risk to general health posed by dental disease or its treatment. A high proportion of parents felt that simple dietary and oral hygiene advice was necessary, that the benefits of fluoride supplementation should be explained and that free fluoride supplements should be issued. The 'family dentist' was most favoured as the source of advice, closely followed by a community dental officer. Likewise the dental surgery was the most popular location for receiving advice, and doctors' surgeries were the least favoured. Parental support for regular school dental screening examinations of all children was extremely high and parents thought that special-needs children should be examined more frequently.

Effect of acute and repeated exposure to low doses of hydrazine on hepatic microsomal enzymes and biochemical parameters in vivo.

A single dose of hydrazine (3 mg.kg-1 i.p.) caused hepatic accumulation of triglycerides and depletion of ATP in rats after 9 h. Repeated exposure of rats to hydrazine (approximately equal to 2.5 mg.kg-1 per day) for 10 days resulted in depletion of hepatic reduced glutathione (GSH) and triglycerides. Repeated exposure to hydrazine also caused a significant (time dependent) induction of p-nitrophenol hydroxylase (NPH) activity together with changes in other hepatic microsomal enzymes. These included 7-pentoxyresorufin O-deethylase (PROD) and 7-ethoxyresorufin O-de ethylase (EROD) activity, total cytochrome P450, cytochrome b5 and cytochrome P450 reductase activity. Repeated exposure to lower levels of hydrazine (approximately equal to 0.250 mg.kg-1 per day) caused no significant hepatic biochemical or microsomal changes after 5 or 10 days except for an increase in NPH activity (17%) and liver ATP (15%) after 5 days.

Influence of inducers and inhibitors of cytochrome P450 on the hepatotoxicity of hydrazine in vivo.

Hydrazine hepatotoxicity in vivo, as manifested by triglyceride accumulation, depletion of ATP and reduced glutathione (GSH) was shown to be dose related. The effect of pretreatment of rats with various inhibitors and inducers of cytochrome P450 on these dose-response relationships was investigated. Pretreatment with the inhibitor piperonyl butoxide increased triglyceride accumulation whereas pretreatment with the inducers phenobarbital and beta-naphthoflavone (BNF) resulted in reduced triglyceride accumulation. Pretreatment with the inducers acetone and isoniazid also enhanced triglyceride accumulation. Only phenobarbital pretreatment also significantly reduced GSH and ATP depletion. A linear correlation was found between hepatic glutathione and ATP levels in non-pretreated animals given various doses of hydrazine. However, exponential relationships were found between hepatic triglycerides and both hepatic ATP and glutathione. The results suggest that i) the hepatotoxicity of hydrazine can be modulated by inducing or inhibiting particular isoenzymes of cytochrome P450, ii) ATP and GSH depletion may not be directly involved in the development of fatty liver.

The possibility of school milk as a vehicle for fluoride: epidemiological, organisational and legal considerations.

The aim of this study was to investigate the epidemiological, organisational and legal considerations of using school milk as a vehicle for fluoride. The background to the work was the need to develop alternative methods of fluoride supplementation for high risk groups living in areas where water fluoridation is unlikely. St Helens in Merseyside was chosen as the study area, where 23 per cent of 4-year-old children were identified as having a high caries experience (dmft > or = 4). It was found that 65 per cent of 3 and 4-year-old children attend local authority educational facilities, where milk is provided on a daily basis for children aged 2 to 7 years. This group included 62 per cent of the 4-year-old group with high caries experience. The legal aspects of adding fluoride to milk were found to be complex but it was concluded that there may be considerable potential for using school milk as a vehicle for fluoride, and a large-scale study is now planned.

Referral of child patients from the Community Dental Service to the General Dental Service: one year's experience.

The Community Dental Service has been encouraged to refer regular attending patients to General Dental Practice whilst maintaining a monitoring system to ensure that referred patients do not 'fall through the net'. The referral and monitoring system run by Halton Health Authority for one year is described. During this period 112 motivated patients were identified as being suitable for referral to general practice. Of these, 85 agreed to referral and 27 refused. Of those referred, 69 subsequently attended but 16 failed to attend and 14 of these did not respond to a further recall by the CDS. Far from acting as a safety net service the CDS may, in pursuing this referral policy, be actually increasing the number of irregular attenders in some localities and for this reason Halton is reviewing the speed with which the referral policy is being implemented.