Age and diagnostic performance of Alzheimer disease CSF biomarkers.

OBJECTIVES: Core CSF changes in Alzheimer disease (AD) are decreased amyloid ß(1-42), increased total tau, and increased phospho-tau, probably indicating amyloid plaque accumulation, axonal degeneration, and tangle pathology, respectively. These biomarkers identify AD already at the predementia stage, but their diagnostic performance might be affected by age-dependent increase of AD-type brain pathology in cognitively unaffected elderly. METHODS: We investigated effects of age on the diagnostic performance of CSF biomarkers in a uniquely large multicenter study population, including a cross-sectional cohort of 529 patients with AD dementia (median age 71, range 43-89 years) and 304 controls (67, 44-91 years), and a longitudinal cohort of 750 subjects without dementia with mild cognitive impairment (69, 43-89 years) followed for at least 2 years, or until dementia diagnosis. RESULTS: The specificities for subjects without AD and the areas under the receiver operating characteristics curves decreased with age. However, the positive predictive value for a combination of biomarkers remained stable, while the negative predictive value decreased only slightly in old subjects, as an effect of the high AD prevalence in older ages. CONCLUSION: Although the diagnostic accuracies for AD decreased with age, the predictive values for a combination of biomarkers remained essentially stable. The findings highlight biomarker variability across ages, but support the use of CSF biomarkers for AD even in older populations.

Estrogen and progesterone treatment: effects on muscarinic M(4) receptor subtype in the rat brain.

We investigated the effect of ovariectomy (OVX) and hormonal treatment for 10 weeks by estradiol and progesterone on muscarinic M(4) receptor subtype in different brain areas of female rats. Moreover, motor activity of OVX and hormone-treated rats was measured by automated open field exploration boxes. Receptor quantification in the hippocampus, frontal cortex, parietal cortex, amygdala and hypothalamus was done by receptor autoradiography using a selective ligand for muscarinic M(4) receptors. Ovariectomy up-regulated M(4) receptors in the dentate gyrus, CA1, CA3, frontal cortex and hypothalamus whereas the estrogen treatment restored M(4) binding to that of the sham group. Progesterone treatment had no effect on the ovariectomy-induced up-regulation of M(4) receptors. Ovariectomy significantly decreased the exploratory activity of the rats compared to the sham group. Estrogen treatment restored the exploratory behavior of the ovariectomized rats to that of the sham group whereas the progesterone-treated rats were less alert to the surrounding when compared to the sham and estrogen supplemented rats. The effect of estrogen on the hippocampal muscarinic M(4) receptor subtype is a novel finding and may have functional significance for cholinergic receptors especially in relation to postmenopausal memory problems and neurodegenerative disease like Alzheimer's disease.

Snake toxins with high selectivity for subtypes of muscarinic acetylcholine receptors.

There are five subtypes of muscarinic acetylcholine receptors (M(1) to M(5)) which control a large number of physiological processes, such as the function of heart and smooth muscles, glandular secretion, release of neurotransmitters, gene expression and cognitive functions as learning and memory. A selective ligand is very useful for studying the function of a subtype in presence of other subtypes, which is the most common situation, since a cell or an organ usually has several subtypes. There are many non-selective muscarinic ligands, but only few selective ones. Mambas, African snakes of genus Dendroaspis have toxins, muscarinic toxins, that are selective for M(1), M(2) and M(4) receptors. They consist of 63-66 amino acids and four disulfides which form four loops. They are members of a large group of snake toxins, three-finger toxins; three loops are extended like the middle fingers of a hand and the disulfides and the shortest loop are in the palm of the hand. Some of the toxins target the allosteric site which is located in a cleft of the receptor molecule close to its extracellular part. A possible explanation to the good selectivity is that the toxins bind to the allosteric site, but because of their size they probably also bind to extracellular parts of the receptors which are rather different in the various subtypes. Some other allosteric ligands also have good selectivity, the alkaloid brucine and derivatives are selective for M(1), M(3) and M(4) receptors. Muscarinic toxins have been used in several types of experiments. For instance radioactively labeled M(1) and M(4) selective toxins were used in autoradiography of hippocampus from Alzheimer patients. One significant change in the receptor content was detected in one region of the hippocampus, dentate gyrus, where M(4) receptors were reduced by 50% in patients as compared to age-matched controls. Hippocampus is essential for memory consolidation. M(4) receptors in dentate gyrus may play a role, since they decreased in Alzheimers disease which destroys the memory. Another indication of the role of M(4) receptors for memory is that injection of the M(4) selective antagonist muscarinic toxin 3 (M(4)-toxin 1) into rat hippocampus produced amnesia.

Inhibition of acetylcholine muscarinic M(1) receptor function by the M(1)-selective ligand muscarinic toxin 7 (MT-7).

MT-7 (1 - 30 nM), a peptide toxin isolated from the venom of the green mamba Dendroaspis angusticeps and previously found to bind selectively to the muscarinic M(1) receptor, inhibited the acetylcholine (ACh)-stimulated [(35)S]-guanosine-5'-O-(3-thio)triphosphate ([(35)S]-GTPgammaS) binding to membranes of Chinese hamster ovary (CHO) cells stably expressing the cloned human muscarinic M(1) receptor subtype. MT-7 failed to affect the ACh-stimulated [(35)S]-GTPgammaS binding in membranes of CHO cells expressing either the M(2), M(3) or M(4) receptor subtype. In N1E-115 neuroblastoma cells endogenously expressing the M(1) and M(4) receptor subtypes, MT-7 (0.3 - 3.0 nM) inhibited the carbachol (CCh)-stimulated inositol phosphates accumulation, but failed to affect the CCh-induced inhibition of pituitary adenylate cyclase activating polypeptide (PACAP) 38-stimulated cyclic AMP accumulation. In both CHO/M(1) and N1E-115 cells the MT-7 inhibition consisted in a decrease of the maximal agonist effect with minimal changes in the agonist EC(50) value. In CHO/M(1) cell membranes, MT-7 (0.05 - 25 nM) reduced the specific binding of 0.05, 1.0 and 15 nM [(3)H]-N-methylscopolamine ([(3)H]-NMS) in a concentration-dependent manner, but failed to cause a complete displacement of the radioligand. Moreover, MT-7 (3 nM) decreased the dissociation rate of [(3)H]-NMS by about 5 fold. CHO/M(1) cell membranes preincubated with MT-7 (10 nM) and washed by centrifugation and resuspension did not recover control [(3)H]-NMS binding for at least 8 h at 30 degrees C. It is concluded that MT-7 acts as a selective noncompetitive antagonist of the muscarinic M(1) receptors by binding stably to an allosteric site.

Multiforme skin lesions in Yekatit 12 Hospital, 1976-1994.

Because the number of cases of multiforme skin lesions encountered in the medical department of Yekatit 12 Hospital has increased in recent years, we conducted a retrospective study to identify the likely precipitating factors and the possible relationship of these with HIV infection. Forty-seven patients with Multiforme Skin Lesions (29 males, 18 females) were admitted between 1976 and January 1994, of whom 43 (92%) were admitted in the past 5 years. Most patients were aged 15-49 years. Thirty patients (64%) were discharged improved and 14 (30%) expired in hospital. The outcome of 3 patients are not known. The charts of only 16 patients could be retrieved for review. Fifteen of these (94%) gave a history of intake of streptomycin, isoniazed and thiacetazone prior to developing the skin manifestation. The anti-TB medications were discontinued initially; 14 patients were restarted on STM, INH and ethambutol without recurrence of the rash. All but 1 were discharged improved. HIV screening tests were done on 24 patients with multiforme skin lesion of whom 21 (88%) were seropositive. Our study suggested that the adverse effects of thiacetazone are increased in HIV associated tuberculous patients. We recommend that further studies be conducted in HIV seropositive and seronegative patients.

Rapid reversed-phase high-performance liquid chromatography method for quantitation, at high pH, of the recombinant apolipoprotein A-IMilano in Escherichia coli fermentation broth.

An automated reversed-phase high-performance liquid chromatography method for quantitative determination of recombinant apolipoprotein A-IMilano (r-Apo A-IM) in E. coli fermentation broth has been developed and evaluated. The use of a unique matrix (Poros IIR/H) makes it possible to achieve rapid separation and good resolution at high pH. The r-Apo A-IM-containing fraction is well separated from other proteins allowing a reliable quantification. The automation and high sample throughput of this method makes it very useful for routine determination of r-Apo A-IM in fermentation broth and in eluates from the various purfication steps. With suitable modifications and adaptions this method is likely to be useful for similar rapid analytical determination of recombinant proteins in complex solutions.

Prevalence and outcomes of sexual violence among high school students.

A cross sectional, school-based survey using self administered anonymous questionnaire was conducted in Addis Ababa and Western Shoa among high school students to determine the prevalence, and reported outcomes of sexual violence. A total of 1401 female students were involved in the study. The prevalence of completed rape and attempted rape among female students was 5% and 10% respectively. The age range of completed rape was between 12-23 years and 61/72 (85%) of the rape victims were under 18 years of age. No significant linear trend was observed among the different age intervals (Chi Square for linear trend = 1.18; p-value = 0.27). Of the total respondents 78%, believed that rape was a major problem. Sexual harassment was reported in 74% of female students. Among the seventy two girls who reported to be raped 17(24%) had vaginal discharge and 12(17%) became pregnant. Social isolation, fear and phobia, hopelessness and suicide attempt were reported in 33%, 19%, 22%, 6% of rape victims, respectively. It is concluded that the prevalence of sexual violence among high school students is a serious problem and concern. Awareness creation to adolescents and the family need to be introduced and schools should also devise appropriate sex education regarding damaging effect of rape and educate youth on sexuality and responsible sexual decision making.