Lovastatin stimulates up-regulation of alpha7 nicotinic receptors in cultured neurons without cholesterol dependency, a mechanism involving production of the alpha-form of secreted amyloid precursor protein

The cholesterol-lowering drug lovastatin enhances the secretion of the alpha-secretase cleavage product of amyloid precursor protein (APP). To investigate whether this effect is mediated via activation of alpha7 nicotinic acetylcholine receptors (nAChRs), we treated SH-SY5Y cells and PC12 cells with lovastatin and measured the levels of alpha7 nAChRs, the alpha-form of secreted APP (alphaAPPs), and lovastatin-related lipids, including cholesterol and ubiquinone. The results showed that low concentrations of lovastatin significantly induced up-regulation of alpha7 nAChRs. No effects of lovastatin were observed on alpha3-containing nAChRs, muscarinic receptors, or N-methyl-D-aspartate receptors. alphaAPPs levels increased in the culture medium of cells treated with lovastatin, whereas no change in whole APP was observed. The increase in alphaAPPs was inhibited by prior exposure of these cells to alpha-bungarotoxin, an antagonist of alpha7 nAChRs. The concentrations of lovastatin used in the study did not change the cholesterol content, but high doses can decrease the levels of ubiquinone and cell viability. These results indicate that lovastatin may play a neuronal role that is cholesterol independent. We also show that the up-regulation of alpha7 nAChRs stimulated by lovastatin is involved in a mechanism that enhances production of alphaAPPs during APP processing.     

Pulmonary epithelial integrity in children: relationship to ambient ozone exposure and swimming pool attendance

Airway irritants such as ozone are known to impair lung function and induce airway inflammation. Clara cell protein (CC16) is a small anti-inflammatory protein secreted by the nonciliated bronchiolar Clara cells. CC16 in serum has been proposed as a noninvasive and sensitive marker of lung epithelial injury. In this study, we used lung function and serum CC16 concentration to examine the pulmonary responses to ambient O3 exposure and swimming pool attendance. The measurements were made on 57 children 10-11 years of age before and after outdoor exercise for 2 hr. Individual O3 exposure was estimated as the total exposure dose between 0700 hr until the second blood sample was obtained (mean O3 concentration/m3 times symbol hours). The maximal 1-hr value was 118 microg/m3 (59 ppb), and the individual exposure dose ranged between 352 and 914 microg/m3hr. These O3 levels did not cause any significant changes in mean serum CC16 concentrations before or after outdoor exercise, nor was any decrease in lung function detected. However, children who regularly visited chlorinated indoor swimming pools had significantly lower CC16 levels in serum than did nonswimming children both before and after exercise (respectively, 57 +/- 2.4 and 53 +/- 1.7 microg/L vs. 8.2 +/- 2.8 and 8.0 +/- 2.6 microg/L; p < 0.002). These results indicate that repeated exposure to chlorination by-products in the air of indoor swimming pools has adverse effects on the Clara cell function in children. A possible relation between such damage to Clara cells and pulmonary morbidity (e.g., asthma) should be further investigated.     

Impact of cadmium exposure on male sex hormones: a population-based study in China

The objective of this study was to investigate the possible effects of environmental cadmium (Cd) exposure on the levels of serum sex hormones in a Chinese population group. A total of 263 male volunteers were included. Blood samples were collected for the determination of serum testosterone (T), measured by radioimmunoassay, and follicle stimulating hormone (FSH) and luteinizing hormone (LH), both measured by enzyme immunoassays. Urinary and blood Cd were analyzed by atomic absorption spectroscopy (AAS). We found a dose-response relationship between urinary Cd excretion and the prevalence of abnormally high serum T levels, but, through multiple regression analysis, we could not trace exposure to Cd as a significant determinant of serum T levels. Exposure to Cd also failed to influence the levels of FSH and LH in serum. In contrast, we found that age, body mass index (BMI), and smoking habits are significant determinants of FSH and LH and of T and LH, respectively. We conclude that oral Cd exposure is not a critical determinant of hormone homeostasis in males, but lifestyle and some biological factors, such as age and BMI, are important. The relationship found between urinary Cd and high T levels may be of importance for male reproductive morbidity and should be investigated further.     

Reduced levels of Abeta 40 and Abeta 42 in brains of smoking controls and Alzheimer's patients

The effects of nicotine on levels of Abeta 40 and Abeta 42 and nicotinic receptor binding sites were studied in brains from nonsmoking and smoking patients with Alzheimer's disease (AD) and aged-matched controls. The levels of soluble and insoluble Abeta 40 and Abeta 42 in frontal cortex and Abeta 40 in temporal cortex and hippocampus were significantly decreased in smoking AD patients compared to nonsmokers with AD. In smoking controls the levels of soluble and insoluble Abeta 40 and Abeta 42 in the frontal and temporal cortex were significantly lower than in nonsmoking controls. The binding of [(3)H]cytisine in temporal cortex was significantly increased in smokers with AD compared to nonsmokers with AD. In smoking controls [(3)H]cytisine and [(3)H]epibatidine binding were significantly increased from 1.5- to 2-fold compared to nonsmoking controls whereas binding sites for [(125)I]alpha-bungarotoxin was less up-regulated. These results indicate that selective nicotinic receptor agonists may be a novel protective therapy in AD by reducing Abeta levels as well as the loss of nicotinic receptors in AD brain.     

Fluorescence in situ hybridization: method of choice for a definitive diagnosis of mantle cell lymphoma

Fluorescence in situ hybridization (FISH) using IGH/CCND1 probes was used to analyze 35 specimens including 27 paraffin sections, 3 bone marrow aspirates, and 5 peripheral blood smears. The 27 paraffin sections included 7 bone marrows, 10 lymph nodes, 3 spleens, 3 tonsils, 3 gastrointestinal biopsies, and 1 skin biopsy. Among these cases, 23 specimens were from 20 patients with mantle cell lymphoma (MCL) and 12 specimens were from 12 patients with non-MCL lymphomas/lymphoid hyperplasia. Specimens from all MCL patients showed positive results with FISH. In one patient, the archived paraffin sections were negative with FISH, but a fresh peripheral blood specimen showed a positive result. Negative results were obtained in all specimens from non-MCL cases. Flow cytometric analysis revealed that all cases of MCL showed CD19/CD5 staining, but the percentages of cells positive for CD23 and FMC-7 were variable, thus they cannot be depended upon for a definitive diagnosis of MCL. Immunohistochemical stains demonstrated positive staining for CD5 and CD20 and negative staining for CD23 in MCL cases but cyclin D1 was positive in only 10 of 13 MCL cases studied. Therefore, it appears that immunophenotyping alone is not sufficient to establish a definitive diagnosis of MCL. FISH should be routinely used when the diagnosis needs confirmation. FISH can be performed in a routine clinical laboratory, and it is applicable to archived material for retrospective studies. Other molecular cytogenetic techniques in comparison with FISH are discussed.     

Impaired cerebral glucose metabolism and cognitive functioning predict deterioration in mild cognitive impairment

The objective of this study was to assess whether reduced glucose metabolism (rCMRGlu) and cognitive functioning could predict development of Alzheimer's disease (AD) in subjects with mild cognitive impairment (MCI). Twenty MCI patients underwent baseline and follow-up investigations of rCMRGlu, as measured by PET, and cognitive function measured by neuropsychological test assessments. Subjects were clinically followed up with an average interval of 36.5 months. Two groups were obtained after the second clinical assessment. Nine patients were diagnosed as AD and classified as progressive MCI (P-MCI), whereas 11 patients remained clinically stable and were classified as stable MCI (S-MCI). There were no differences in demographic variables or baseline MMSE between the two subgroups. Logistic regression indicated the two variables that most effectively predicted future development of AD were rCMRGlu from the left temporoparietal area and performance on the block design. These combined measures gave an optimal 90% correct classification rate, whereas only rCMRGlu or neuropsychology alone gave 75% and 65% correct classification, respectively. Measures of temporoparietal cerebral metabolism and visuospatial function may aid in predicting the evolution to AD for patients with MCI.     

Responder characteristics to a single oral dose of cholinesterase inhibitor: a double-blind placebo-controlled study with tacrine in Alzheimer patients

A proportion of Alzheimer's disease (AD) patients treated for several months with cholinesterase (ChE) inhibitors have shown some favorable response on cognition, but the characteristics of the responders are still unclear. This study attempts to identify the characteristics of individuals with a positive behavioral response after a double-blind randomized administration of a single oral dose of tacrine (40 mg) and placebo to AD patients. Furthermore, the relationship between single-dose and long-term responders are examined. Twenty-four mildly to very mildly demented AD patients participated in the study. They all fulfilled the diagnosis of probable AD according to NINCDS-ADRDA criteria. Active treatment (tacrine 40 mg) and placebo was administered in random order on 2 consecutive days, and the effects were evaluated within 2 h using neuropsychological tests (assessing visuospatial ability, episodic memory and attention), registration of EEG activity and measurement of red blood cells (RBC) acetylcholinesterase (AChE), ChE activity and concentrations of tacrine and its metabolites in plasma. Results demonstrated significant improvement, tacrine compared to placebo, in measures of attention, but not in episodic memory or visuospatial ability. A single-dose response was therefore defined in terms of improvement in attention. The tacrine plasma concentration (pcTHA) showed a positively skewed distribution (mean +/- SD: 10.5 +/- 11.8, range: 1.0-51.8 ng/ml). There were no significant differences between single-dose responders compared to nonresponders in pcTHA, metabolites of tacrine, inhibition of AChE in RBC, tau levels in CSF, AChE activity in CSF or plasma and demographic variables. However, single-dose responders showed a higher right frontal alpha/theta ratio on EEG and had lower glucose metabolism in the parietal-temporal association cortex at baseline. In addition, the frequency of apolipoprotein E (APOE) epsilon 4 alleles was higher in responders. Interestingly, the single-dose response was related to the long-term response, although not significantly, which probably was due to lack of power. To conclude, the present study identified single-dose responders in terms of improved attentional performance associated with a relatively higher alpha/theta activity in the right frontal regions of the brain measured on EEG and predominance of APOE epsilon 4 allele.     

In vitro binding of3H-acetylcholine to nicotinic receptors in rodent and human brain

Summary The binding of³H-acetylcholine (³H-ACh) to nicotinic receptors in rodent and human brain was measured in the presence of atropine to prevent binding to muscarinic binding sites.³H-ACh binds specifically and saturably to rodent brain. From saturation binding K_d was 30 nM in rat cerebral cortex, which is close to that calculated from kinetic experiments. The binding was temperature-dependent, being highest at low temperatures and decreasing at higher temperatures. The regional distribution of binding in mouse brain was not uniform. The binding was highest in the midbrain, intermediate in the cerebral cortex and striatum, and lowest in the cerebellum, hippocampus, hypothalamus and medulla oblongata. No significant correlation was found between the regional³H-ACh binding and the regional binding of³H-alpha-bungarotoxin (³H-BTX),³H-nicotine (³H-NIC),³H-tubocurarine and the endogenous acetylcholine content, although the correlation value for³H-ACh/³H-NIC was at the limit for significance.³H-ACh also bound specifically to human cerebral cortical tissue and this binding was approximately three times lower than in rodent brain, when a low³H-ACh concentration was used. In contrast to rat brain there appears to exist multiple binding sites for³H-ACh in human cerebral cortex as suggested by the curvelinear nature of the Scatchard plot. It was calculated that³H-ACh bound with K_d 4 nM and B_max 8 pmol/g protein and K_d 112 nM and B_max 67 pmol/g protein. The Hill number of 1.5 for the binding of low concentration and 2.5 for high concentration of³H-ACh also suggest that the³H-ACh-binding sites interaction exhibit positive cooperativity.