Brain neurons and glial cells express Neu differentiation factor/heregulin: a survival factor for astrocytes.

Neu differentiation factor (NDF, also called heregulin) was isolated from mesenchymal cells on the basis of its ability to elevate phosphorylation of ErbB proteins. Earlier in situ hybridization analysis showed that NDF was transcribed predominantly in the central nervous system during embryonic development. To gain insights into the role of NDF in brain we analyzed its distribution by immunohistochemistry and in situ hybridization. Late-gestation (day 17) rat embryos displayed high NDF immunoreactivity in both motor (e.g., putamen) and limbic (e.g., septum) regions. Lower levels of the factor were exhibited by adult brain, except for the cerebellum, where NDF expression was increased postnatally. Both neurons and glial cells were identified by immunohistochemistry as NDF-producing cells (e.g., pyramidal neurons in the cerebral cortex and glial cells in the corpus callosum). By establishment of primary cultures of rat brain cells we confirmed that NDF was expressed in neurons as well as in astrocytes. In addition, by using such primary cultures we observed that NDF treatment exerted only a limited mitogenic effect, which was accompanied by significant acceleration of astrocyte maturation. Furthermore, long-term incubation with the factor specifically protected astrocytes from apoptosis, implying that NDF functions in brain as a survival and maturation factor for astrocytes.     

C7 complement deficiency in an Israeli Arab village

Deficiencies of terminal complement components, particularly the latter ones, are often detected because of increased susceptibility to Neisserial infections. Herein we document the first report of C7 deficiency among a highly inbred Arab population living in the lower Galilee region of Israel. Both biochemical and molecular analysis were performed on samples from infected survivors and parents of children who succumbed to Neisserial infections in a 4-year period. Only the index case who suffered recurrent infections and a sibling who had not suffered an infection during the outbreak were found to be C7-deficient. The mutation was found to be the one previously described to be prevalent among Israeli Jews of Moroccan ancestry (mutation G1135C). The implications of this finding are discussed in the context of family pedigree, the protective effect of complement deficiency, and the clinical outcome.     

Amino acid substitutions within the heptad repeat domain 1 of murine coronavirus spike protein restrict viral antigen spread in the central nervous system

Targeted recombination was carried out to select mouse hepatitis viruses (MHVs) in a defined genetic background, containing an MHV-JHM spike gene encoding either three heptad repeat 1 (HR1) substitutions (Q1067H, Q1094H, and L1114R) or L1114R alone. The recombinant virus, which expresses spike with the three substitutions, was nonfusogenic at neutral pH. Its replication was significantly inhibited by lysosomotropic agents, and it was highly neuroattenuated in vivo. In contrast, the recombinant expressing spike with L1114R alone mediated cell-to-cell fusion at neutral pH and replicated efficiently despite the presence of lysosomotropic agents; however, it still caused only subclinical morbidity and no mortality in animals. Thus, both recombinant viruses were highly attenuated and expressed viral antigen which was restricted to the olfactory bulbs and was markedly absent from other regions of the brains at 5 days postinfection. These data demonstrate that amino acid substitutions, in particular L1114R, within HR1 of the JHM spike reduced the ability of MHV to spread in the central nervous system. Furthermore, the requirements for low pH for fusion and viral entry are not prerequisites for the highly attenuated phenotype.     

Accumulation of closed-circular polyoma DNA molecules containing host DNA during serial passage of the virus

The high-multiplicity serial passage of plaque-purified polyoma virus in baby mouse kidney cultures results in the accumulation of closed-circular virus DNA molecules containing covalently linked sequences homologous to reiterated mouse cell DNA. Such molecules can be encapsidated within virions and are probably defective in plaque formation.     

The occurrence of the tropical bedbug (Cimex hemipterus, fabricius) in poultry barns in Israel

The occurrence of the tropical bedbug (Cimex hemipterus Fabricius) in poultry houses in Israel is described. Despite the heavy infestation serious losses have not been registered and no clinical signs observed. Treatment of the barns and accessories with 2% malathion emulsion gave good results. The parasite invaded human habitations as well.     

CEBQ: Composite Eating Behavior Questionnaire--development and performance

Poor eating behavior is an important nutritional risk factor among community dwelling elders, and precedes overt malnutrition in the majority of cases. Several tools were developed to assess nutritional risk through evaluating eating behavior. All containing elements shown to be related to nutritional decline. Given the diversity of the geriatric population each tool may apply to specific subsets of the population but not to all. The ideal tool may be a questionnaire tailored for the study population based on a pool of methods and questions. We describe the development and use of such a composite tool, and compares its performance to other questionnaires. Our results show that in community dwelling elders nutrition risk assessments such as the NRI or eating behavior score were not predictive of nutritional status measured by dietary intake, weight change or BMI. Subjective appetite assessment was the most predictive question for nutritional decline. We describe the questionnaire and its development and offer general advice to its future implementations.     

The association between melatonin and sleep stages in normal adults and hypogonadal men

The role of melatonin in normal sleep-wake regulation has been inferred from the temporal relationships between its cycle and the 24 h cycle in sleep propensity. Pharmacological doses of melatonin were reported to have sleep-inducing effects in insomniacs. The current study investigated the relationship between melatonin and sleep stages in groups of hypogonadal men with abnormal melatonin levels. We were also interested in examining what would happen to these relationships during testosterone replacement therapy. Male patients with hypogonadotropic hypogonadism (IGD, n = 6), constitutional delayed puberty (DP, n = 6), and Klinefelter's syndrome (KS, n = 5) before and during testosterone replacement therapy were studied. Six patients with KS and normal testosterone levels were also studied. Results were compared with those obtained in normal controls (n = 6). Serum samples were obtained at 15 min intervals from 1900-0700h in a controlled light-dark environment with simultaneous polysomnographic sleep recordings. Serum melatonin levels were the highest in IGD and DP and lowest in KS patients. A lower percentage of sleep stage 2 and higher percentage of stage 3/4 were observed in IGD and DP groups while KS patients had higher percentage of stage 2 and lower percentage of stage 3/4 as compared to controls. Slow wave sleep was the highest in IGD and the lowest in KS groups. Serum melatonin levels were lowest in KS groups. Serum melatonin levels were lowest in sleep stage 3/4, higher in stage 2 and highest in REM sleep when all groups were combined and averaged together. However, in the IGD group, melatonin levels were actually lowest in REM sleep. Also in the KS group, melatonin levels were lower in REM than during sleep stage 2. Serum melatonin levels were lowest in sleep stage 3/4 in all groups, higher in stage 2, and highest in REM sleep. During waking periods, melatonin levels were the highest in untreated IGD, DP and KS patients. Testosterone treatment given to these patients, although normalized, their melatonin levels did not statistically significantly change these correlations. These data demonstrate that relative melatonin concentrations are associated with sleep stages in hypogonadal and normal men. The results also indicate that the association between melatonin and the reproductive hormones are independent of the synchronizing effects of melatonin on sleep homeostasis.     

Nidovirus infections: experimental model systems of human neurologic diseases

The presence of terminally differentiated slow- and non-dividing cells in the central nervous system (CNS) provides a safe harbor for viral persistence and latency and constitutes a unique immunologic environment for viral infections. Studies of experimental model systems of viral infections of the CNS provide insight into mechanisms of viral persistence and immune-mediated pathology. Nidoviruses are comprised of 2 families of viruses, coronaviruses and arteriviruses, and are common pathogens of humans and a variety of animal species. Both families of viruses contain neurotropic strains that produce experimental neurologic diseases in rodents. These include acute meningitis and encephalitis; acute poliomyelitis; and chronic inflammatory, immune-mediated, demyelination. Coronavirus-induced demyelinating disease mimics many of the pathologic features of Multiple Sclerosis (MS).     

Live imaging of induced and controlled DNA double-strand break formation reveals extremely low repair by homologous recombination in human cells

DNA double-strand breaks (DSBs), the most hazardous DNA lesions, may result in genomic instability, a hallmark of cancer cells. The main DSB repair pathways are non-homologous end joining (NHEJ) and homologous recombination (HR). In mammalian cells, NHEJ, which can lead to inaccurate repair, predominates. HR repair (HRR) is considered accurate and is restricted to S, G2 and M phases of the cell cycle. Despite its importance, many aspects regarding HRR remain unknown. Here, we developed a novel inducible on/off switch cell system that enables, for the first time, to induce a DSB in a rapid and reversible manner in human cells. By limiting the duration of DSB induction, we found that non-persistent endonuclease-induced DSBs are rarely repaired by HR, whereas persistent DSBs result in the published HRR frequencies (non-significant HR frequency versus frequency of ～10%, respectively). We demonstrate that these DSBs are repaired by an accurate repair mechanism, which is distinguished from HRR (most likely, error-free NHEJ). Notably, our data reveal that HRR frequencies of endonuclease-induced DSBs in human cells are >10-fold lower than what was previously estimated by prevailing methods, which resulted in recurrent DSB formation. Our findings suggest a role for HRR mainly in repairing challenging DSBs, in contrast to uncomplicated lesions that are frequently repaired by NHEJ. Preventing HR from repairing DSBs in the complex and repetitive human genome probably has an essential role in maintaining genomic stability.