High throughput protein expression screening in the nervous system – needs and limitations

The cellular complexity of the brain (some estimate that there are up to 10³ different cell types) is exceeded by the synaptic complexity, with each of the ∼10¹¹ neurons in the brain having around 10³–10⁴ synapses. Proteomic studies of the synapse have revealed that the postsynaptic density is the most complex multiprotein structure yet identified, with ∼10³ different proteins. Such studies, however, use brain tissue with many different regions and therefore different cell types, and there is clear potential for heterogeneity of protein content at different synapses within and between brain regions. Although large-scale mRNA-based assays are in progress to map this sort of complexity at the cellular level, and indeed all brain-expressed genes, analysis of protein distribution (at synapses and other structures) is still in the very early stages. We review existing large-scale protein expression studies and the specific technical obstacles that need to be overcome before applying the scaling used in nucleic acid based approaches.     

Role of interleukin 6 in the growth of myeloma-derived cell lines.

The role of interleukin 6 (IL-6) in the growth of five multiple myeloma-derived cell lines was characterized. The U266 and RPMI 8226 cell lines demonstrated increased DNA synthesis when cultured with exogenous IL-6, expressed IL-6 cell surface receptors (IL-6Rs) and expressed mRNA for IL-6R. However, these cells did not secrete detectable IL-6 protein, and a neutralizing antibody to IL-6 did not inhibit their growth. Three other myeloma-derived cell lines ARH-77, IM-9 and HS-Sultan did not respond to exogenous IL-6, secrete IL-6 or express cell surface IL-6Rs. The IL-6 responsive cell lines bore late B-cell surface antigens (Ags), CD38 and PCA-1, whereas those lines which were non-IL-6 responsive strongly expressed B1 (CD20) and B4 (CD19) Ags, representing earlier stages in B-cell differentiation. Finally, the two IL-6 responsive cell lines did not express Epstein-Barr virus (EBV) proteins; in contrast, EBV encoded proteins typically expressed during latency could be detected in the three non-IL-6 responsive lines, confirming infection with virus. These studies clarify the heterogeneity observed in the myeloma cell line phenotype and biology and suggest that the U266 and RPMI 8226 cell lines, which express IL-6 cell surface receptors and are IL-6 responsive, may be useful for further study of IL-6 signal transduction in and related IL-6 mediated growth of myeloma in vivo. In contrast, those cell lines which are IL-6-independent provide a model for further study of EBV transformation and IL-6-dependent growth mechanisms in malignancy.     

A nationwide survey of excessive daytime sleepiness in Parkinson's disease in France

To determine the prevalence of excessive daytime sleepiness (EDS) and that of dozing and sudden onset of sleep episodes (SOS) while driving in ambulatory patients with Parkinson's disease (PD) in France, a national sample of private and public neurologists was asked to recruit the first 10 consecutive nondemented PD patients. Each patient completed a questionnaire including the Epworth Sleepiness Scale (ESS) and the likelihood of dozing off and experiencing SOS episodes behind the wheel. Clinical and demographic data were collected. One thousand six hundred and twenty‐five patients with PD were included in the survey. Twenty‐nine percent of the patients suffered from EDS (ESS score ≥10) but only 0.8% declared a high chance of dozing while driving and 0.5% reported totally unpredictable SOS episodes while driving. Risk factors for EDS were male gender, reduced activity of daily living, and a high daily levodopa equivalent dosage. Risk factors for SOS episodes while driving were an ESS score ≥10, male gender, and low Hoehn and Yahr staging. EDS is common in ambulatory patients with PD and is a major risk factor for dozing and for SOS episodes behind the wheel in patients who drive. © 2007 Movement Disorder Society     

Zinc takes the center stage: its paradoxical role in Alzheimer’s disease

There is compelling evidence that the etiology of Alzheimer’s disease (AD) involves characteristic amyloid-β (Aβ) deposition, oxidative stress, and anomalous metal–Aβ protein interaction. New studies have implicated redox active metals such as copper, iron, and zinc as key mediating factors in the pathophysiology of Alzheimer’s disease. There is also evidence that drugs with metal chelating properties could produce a significant reversal of amyloid-β plaque deposition in vitro and in vivo. This paper reviews current observations on the etiologic role of zinc in AD. We also discuss the interactions of zinc and copper with Aβ, a factor that purportedly facilitates disease processes. Finally, we review the protective role of zinc against Aβ cytotoxicity and hypothesize how the apparent effect of zinc on AD pathology may be paradoxical, The Zinc Paradox. Indeed, complex pathologic stressors inherent to the Alzheimer’s diseased brain dictate whether or not zinc will be neuroprotective or neurodegenerative. Further research on the zinc paradox in AD is needed in order to elucidate the exact role zinc plays in AD pathogenesis.     

The emerging role of induced hypothermia in the management of acute stroke.

Current treatment of acute stroke remains unsatisfactory. This review presents experimental and clinical data which suggest that mild induced hypothermia could be a potent and practicable neuroprotective treatment of acute ischaemic stroke and intracerebral haemorrhage. Hypothermia, if proven to be safe, effective and widely practicable in patients with acute stroke, could have an enormous positive impact on reducing the burden of stroke worldwide. Critical issues that will need to be considered in a well designed randomised controlled trial of induced hypothermia in acute stroke patients are discussed.     

Reduced blood clearance and increased urinary excretion of N-nitrosodimethylamine in patas monkeys exposed to ethanol or isopropyl alcohol.

Low concentrations of N-nitrosodimethylamine are metabolized in rodent and human liver by cytochrome P450IIE1, an activity competitively inhibitable by ethanol. In rodents coadministration of ethanol with N-nitrosodimethylamine results in increased tumorigenicity in extrahepatic organs, probably as a result of reduced hepatic clearance. To test this concept in a primate, the effects of ethanol cotreatment on the pharmacokinetics of N-nitrosodimethylamine were measured in male patas monkeys. Ethanol, 1.2 g/kg given p.o. before i.v. N-nitrosodimethylamine (1 mg/kg) or concurrently with an intragastric dose resulted in a 10-50-fold increase in the area under the blood concentration versus time curves and a 4-13-fold increase in mean residence times for N-nitrosodimethylamine. Isopropyl alcohol, 3.2 g/kg 24 h before N-nitrosodimethylamine, also increased these parameters 7-10-fold; this effect was associated with persistence of isopropyl alcohol and its metabolic product acetone, both IIE1 inhibitors, in the blood. While no N-nitrosodimethylamine was detected in expired air, trace amounts were found in urine. Ethanol and isopropyl alcohol pretreatment increased the maximum urinary N-nitrosodimethylamine concentration 15-50-fold and the percentage of the dose excreted in the urine by 100-800-fold. Thus ethanol and isopropyl alcohol greatly increase systemic exposure of extrahepatic organs to N-nitrosodimethylamine in a primate.     

Transvaginal sonography of cervical width and length during pregnancy.

Transvaginal ultrasonography has been proposed as a reliable method of assessing dimensions of the cervix. The purpose of the current investigation was to establish normative data for cervical width and length during pregnancy. This information may be helpful in predicting patients at risk for preterm birth. A transvaginal 5 or 7.5 MHz transducer was used on 132 consecutive low-risk pregnant women undergoing evaluation for gestational dating purposes. Even in cases of patient obesity or an empty bladder, high resolution was possible and permitted cervical measurement in all but one case. The external cervical width at the vaginal fornices was found to increase with advancing gestation (R = 0.512, P < 0.005). The cervical length from internal os to external os was found not to change with advancing gestation (R = 0.11, P = 0.30). Using these normative data, investigation is recommended to determine whether measuring cervical width and length is useful in predicting preterm labor and delivery.