Complex pharmacological properties of recombinant alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor subtypes.

The pharmacological properties of two glutamate receptor subtypes, GluR-A/B and GluR-B/D, were examined in RNA-injected Xenopus oocytes using two-electrode voltage clamp. Concentration-response relations revealed that the potencies of L-glutamate, kainate, and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) varied slightly between the two receptor subtypes, but the rank order of agonist potency did not. The EC50 values for GluR-A/B receptors were 3.31 microM for AMPA, 6.16 microM for glutamate, and 57.5 microM for kainate, whereas the EC50 values for GluR-B/D receptors were 5.01 microM, 32.3 microM, and 64.6 microM for AMPA, L-glutamate, and kainate, respectively. The potencies of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(f)quinoxaline (NBQX) were quantified by Schild analysis. The potency of NBQX at blocking currents mediated by GluR-A/B receptors changed depending on the agonist used to activate the receptors (pA2 values were as follows: for block of kainate, 7.23 +/- 0.01; L-glutamate, 6.78 +/- 0.02; AMPA, 6.95 +/- 0.02). Differences between agonists were less marked in cells expressing GluR-B/D receptors (pA2 values: kainate, 7.28 +/- 0.01; L-glutamate, 7.30 +/- 0.02; AMPA, 7.35 +/- 0.01). In each case, the slope of the Schild regression was not different from unity, consistent with competitive antagonism of these receptors by NBQX. CNQX also blocked GluR-A/B and GluR-B/D receptors competitively but was less potent than NBQX and did not differentiate between agonists or subunit combination. These data suggest that L-glutamate, kainate, and AMPA bind to different receptor substructures on recombinant AMPA receptors and that NBQX but not CNQX binds to these sites with different affinities. Moreover, because the properties of these binding sites vary between GluR-A/B and GluR-B/D receptors, our findings provide a basis for mutational analysis aimed at identifying receptor domains involved in agonist and antagonist binding.     

Interobserver variability in neonatal cranial ultrasonography

The reliability of cranial ultrasound diagnosis in the premature neonate was examined using data from an ongoing multicentre study of the epidemiology and long-term consequences of neonatal brain haemorrhage. First week ultrasound films (obtained at 4 hours, 24 hours and 7 days) from 60 study subjects were randomly selected for independent review by two groups of experienced interpreters, and results were recorded separately for observations (i.e. presence or absence of an abnormal echodense area on a film) and interpretations (i.e. presence or absence of haemorrhage or ventricular dilatation) in each hemisphere. Because of deaths in the first week of life, the total number of films examined was 138. Concordance on the presence or absence of an abnormal echodensity was examined for each individual film for three areas of interest: the germinal matrix, the ventricles and the parenchyma. Concordance on the presence or absence of haemorrhage or ventricular dilatation was examined only for the seventh-day film, or the final film prior to death. Finally, concordance was analysed with the diagnostic interpretations grouped into categories thought to differ prognostically for long-term outcome. In general, concordance was poorest for germinal matrix lesions and best for parenchymal lesions. Concordance was lower for observations made on each individual film than it was for interpretation of the final film in each case. Fifty-five of 60 cases (92%) were assigned to the same major prognostic category by both readers. Ultrasound review conferences were held periodically and there was evidence that concordance in ultrasound reading and interpretation improved during the course of the study.     

CAG repeat polymorphism within the KCNN3 gene is a significant contributor to susceptibility to anorexia nervosa: a case-control study of female patients and several ethnic groups in the Israeli Jewish population.

The human small-conductance Ca(2+)-activated potassium channel gene KCNN3 has been involved in mechanisms underlying neuronal function and plasticity. A multiallelic CAG repeat polymorphism within the KCNN3 has been associated with schizophrenia and bipolar disorder. We have previously reported in a family-based study that longer CAG repeats are preferentially transmitted to patients with anorexia nervosa (AN). The present study extends the analysis of KCNN3 allele distribution to a larger series of AN female patients and control groups, incorporating information on ethnicity and co-morbidities associated with AN. The data analysis is presented while considering separately the two alleles of each individual, namely a minor (shorter) and a major (longer) allele. This study has found that the KCNN3 allele distribution in the general Israeli population does not differ significantly in at least four Jewish ethnic groups of Ashkenazi, North African, Iraqi, and Yemenite origin. These have been used as control groups in a matched case-control analysis that has demonstrated a significant over-representation of KCNN3 alleles with longer CAG repeats among AN patients (P < 0.001 for the major allele and P = 0.035 for allele sum). Under dichotomization, a significantly higher prevalence of the L allele (>19 repeats) has been observed among AN patients (P < 0.001). While considering AN and co-morbid phenotypes, a tendency towards longer (L) alleles has been observed in the subset of patients with obsessive-compulsive disorder (OCD) co-morbidity. These findings further implicate KCNN3 as a significant contributor to predisposition to AN.     

Conformation of Replicated Segments of Chromosome Fibres in Human S-phase Nucleus

Recent statistical analysis of the folding of G0/G1 chromosomes using fluorescence in situ hybridization (FISH) allowed development of a random walk/giant loop model of chromosome structure. According to this model there are two levels of organization of G0/G1 chromosome fibres. On the first level, the fibres are arranged in giant loops several Mbp in size, and within each loop the fibres are randomly folded. On the second level, the loop attachment sites form a chromosome backbone that also shows random folding. Newly replicated segments of mammalian chromosomes may be directly visualized at high resolution in S-phase nuclei using immunofluorescent methods and appear as worm-like fibres. In our earlier study, we analysed conformation of the fibres in human cells blocked for 16 h at the G1/S boundary with 5- fluorodeoxyuridine (FdU) and then released into S-phase by the addition of a DNA prec ursor. However, long treatment of cells with FdU induces very short replicons and may promote apoptosis. In this study we analysed conformation of the fibres in normally proliferating human cells that had not been blocked with FdU for a long time. It has been found that replicated chromosome fibres visualized just after 2 h of incubation of the cells with a non-radioactively labelled DNA precursor behave as flexible polymer chains without major constraints, and that their local conformation in the range of several microns of their contour length may be considered as random. Confocal analysis of human X chromosomes visualized in HeLa cells using FISH with a specific painting probe shows that in S-phase the chromosomes occupy distinct nuclear territories and their apparent size does not differ from that in non-S-phase cells. This observation indicates that the second level of chromosome organization also exists in S-phase chromosomes. It appears, theref ore, that the random walk/giant loop model developed earlier for G0/G1 chromosomes is also valid for S-phase chromosomes.     

Public–Private Collaboration in Health and Human Service Delivery: Evidence from Community Partnerships

The collaboration among public–private partnerships that applied to the Community Care Network (CCN) demonstration program of the Hospital Research and Educational Trust is examined. These partnerships link broad-based community coalitions with health and human service providers in efforts to improve community health and local service delivery. Although they willingly collaborated in identifying community health needs, coordinating services, and reporting to the community, partnership participants showed less alacrity in joining forces to reduce redundancy and increase efficiency. Such patterns suggest that organizations might best profit from working together on activities that maintain existing power relations and that have the potential to add prestige and attract new clients. Collaboration in these areas may be essential to building a foundation of trust that leads to future cooperation in more sensitive areas.     

Biochemical markers of compliance in the Physicians' Health Study

The Physicians' Health Study is a randomized, double-blind, placebo-controlled trial using a 2 x 2 factorial design to test the effects of low-dose aspirin on risk of cardiovascular disease and beta-carotene supplementation on the incidence of cancer. To evaluate self-reported compliance with assigned treatment, we measured serum thromboxane B2, which is decreased after aspirin use, and plasma beta-carotene in samples of study participants drawn from three geographic locations in three different time periods. Thromboxane B2 levels were markedly lower in those assigned to aspirin (median = 63.5 pg/mL) than in those given aspirin placebo (median = 3,600 pg/mL, P less than .0001). Similarly, those assigned to beta-carotene had significantly higher levels (median = 1,176 ng/mL) than those given placebo (median = 306 ng/mL, P less than .0001). In addition, there was a highly significant positive correlation between levels of these biochemical markers and the self-reports of compliance (r = 0.65 for thromboxane B2 and r = 0.69 for beta-carotene, P less than .0001). These findings support the validity of the self-reported compliance in the Physicians' Health Study.