Feeding microstructure in diet-induced obesity susceptible versus resistant rats: central effects of urocortin 2

With one billion people overweight worldwide, the need to identify risk factors and treatments for obesity is urgent. The present study determined whether rats genetically prone to diet-induced obesity (DIO) show preexisting differences in meal microstructure and are sensitive to central anorectic effects of corticotropin-releasing factor type 2 (CRF₂) receptor stimulation. Male, selectively bred DIO rats and their diet resistant (DR) counterparts ( n = 9/genotype) were weaned onto low-fat chow and compared as young adults for spontaneous or intracerebroventricular urocortin 2 administration-induced (0, 0.3, 1, 3 μg) differences in ingestion. DIO rats were hyperphagic selectively at the dark cycle onset, showing shorter latencies to initiate feeding, faster returns to eating following meal completion, and a lower satiety ratio than DR rats. At other times, DIO rats had briefer postmeal intervals, but ate smaller and briefer meals, resulting in normal intake. DIO rats also ate faster than DR rats. Urocortin 2 was less potent in DIO rats, ineffective at the 0.3 μg dose, but produced CRF₂ antagonist-reversible anorexia at higher doses. Though heavier, chow-maintained DIO rats were proportionately as or more lean than DR rats. Thus, DIO rats showed signs of a preexisting, heritable deficit in the maintenance of postmeal satiety and a reduced sensitivity to anorectic CRF₂ agonist stimulation. The meal patterns of DIO rats temporally resemble human 'snacking' behaviour, which predicts adult obesity. Because central CRF₂ stimulation retains full anorectic efficacy at higher doses in the DIO model, manipulating this neuropeptidergic system might yield new therapeutic approaches for diet-induced obesity.     

Neuropathogenesis of Chimeric Simian/Human Immunodeficiency Virus infection In Pig-tailed and Rhesus Macaques

We recently reported that a chimeric simian/human immunodeficiency virus (SHIV_KU-1) developed in our laboratory caused progressive depletion of CD4⁺T lymphocytes and AIDS within 6 months of inoculation into pig-tailed macaques (M.nemestrina). None of the pig-tailed macaques showed productive SHIV infection in the central nervous system (CNS). In this report, we show that by further passage of the pathogenic virus in rhesus macaques [M. mulatta], we have derived a new strain of SHIV (SHIV_KU-2) that has caused AIDS and productive CNS infection in 3 of 5 rhesus macaques infected with the virus. Productive replication of SHIV in the CNS was clearly shown by high infectivity titers and p27 protein levels in brain homogenates, and in 2 of the 3 rhesus macaques this was associated with disseminated, nodular, demyelinating lesions, including focal multinucleated giant cell reaction, largely confined to the white matter. These findings were reminiscent of HIV-1 associated neurological disease, and our immunohistochemical and in situ hybridization data indicated that the neuropathological lesions were associated with the presence of SHIV-specific viral antigens and nucleic acid respectively. However, the concomitant reactivation of opportunistic infections in these macaques suggested that such pathogens may have influenced the replication of SHIV in the CNS, or modified the neuropathological sequelae of SHIV infection in the rhesus species, but not in pig-tailed macaques. Our findings in the two species of macaques highlight the complexities of lentiviral neuropathogenesis, the precise mechanisms of which are still elusive.     

The organization and hypothalamic projections of the tuberomammillary nucleus in the rat: an immunohistochemical study of adenosine deaminase-positive neurons and fibers

The intense immunohistochemical reaction for the enzyme adenosine deaminase displayed by neurons in the tuberomammillary nucleus in the rat was used to study the distribution and morphology of cells comprising this nucleus, their fiber fields within the posterior hypothalamus and their projection pathways from the hypothalamus. Neurons immunoreactive for adenosine deaminase were found along ventricular and basal aspects of the hypothalamus from the level of the dorsomedial nucleus to the caudal pole of the mammillary body. Approximately 4500 neurons were seen on each side of the brain. Positive neurons showed a complex distribution, largely avoiding nuclear boundaries within the posterior basal hypothalamus and mammillary body. This distribution is mapped in detail and a nomenclature based on topography is introduced so that different regions of the cell distribution may be discussed more easily. Reactive neurons showed a Golgi-like staining which allowed careful study of their morphology. In general, neurons were large, with major axes of from 22 to 30 micron, and bipolar in shape. A second, smaller cell type, 14-16 micron in diameter was also seen and, although often less intensely stained, it was considered a constituent of tuberomammillary nucleus of the hypothalamus as well. Stained dendritic arbours extended considerable distances from the parent cell bodies and branched regularly. Dendrites showed very sparse spines and had an apparently scalloped surface. Features suggestive of varicose segments of dendrites were also noted. The long, smooth dendrites of positive neurons were often seen to aggregate into bundles which avoided nuclear boundaries and tended to collect adjacent to basal and ventricular surfaces of the posterior hypothalamus. Varicose fibers immunoreactive for adenosine deaminase formed a dense network within the hypothalamus. These fibers were considered to derive from the positive neurons in the tuberomammillary nucleus and were similar to adenosine deaminase-immunoreactive fibers seen throughout much of the rest of the brain. The density of this type of positive fiber was, however, much greater within the hypothalamus. The region of the posterior basal hypothalamus also contained relatively sparse populations of adenosine deaminase-positive fibers, apparently distinct from this network. These consisted of a field of fine fibers in the median division of the medial mammillary nucleus and a few large varicosities in the dorsolateral part of the median eminence.(ABSTRACT TRUNCATED AT 400 WORDS)     

Cytoprotective effect of free radical scavengers against mucosal damage produced by different antirheumatic drugs

Following 200 mg aspirin, 20 mg indomethacin or 100 mg diclofenac, gastric mucosal damage was evoked after five hours in rats. By administering vitamin A, vitamin E, MTDQ (6,6-methylenebis-2,2,4-trimethyl-1,2-dihydroquinoline), vitamin C, lipoic acid and penicillamine intragastrically at the time of the application of the damaging agent, the authors studied the beneficial effect of these free-radical scavengers upon the mucosal lesions. Vitamin C and penicillamine exerted no significant protective effect. Among the other drugs, the most effective were the lipid-soluble ones: vitamin A, vitamin E and MTDQ. The authors hypothesized that the gastric damage may be connected with the degradation of the polyunsaturated fatty acid components of the cellular membranes and thus the lipid-soluble free radical scavengers were able to offer protection.     

Comparison of antibody repertoires against Staphylococcus aureus in healthy individuals and in acutely infected patients

The management of staphylococcal diseases is increasingly difficult with present medical approaches. Preventive and therapeutic vaccination is considered to be a promising alternative; however, little is known about immune correlates of protection and disease susceptibility. To better understand the immune recognition of Staphylococcus aureus by the human host, we studied the antistaphylococcal humoral responses in healthy people in comparison to those of patients with invasive diseases. In a series of enzyme-linked immunosorbent assay analyses performed using 19 recombinant staphylococcal cell surface and secreted proteins, we measured a wide range of antibody levels, finding a pronounced heterogeneity among individuals in both donor groups. The analysis revealed marked differences in the antibody repertoires of healthy individuals with or without S. aureus carriage, as well as in those of patients in the acute phase of infection. Most importantly, we identified antigenic proteins for which specific antibodies were missing or underrepresented in infected patients. In contrast to the well-described transient nature of disease-induced antistaphylococcal immune response, it was demonstrated that high-titer antistaphylococcal antibodies are stable for years in healthy individuals. In addition, we provide evidence obtained on the basis of opsonophagocytic and neutralizing activity in vitro assays that circulating antistaphylococcal serum antibodies in healthy donors are functional. In light of these data we suggest that proper serological analysis comparing the preexisting antibody repertoires of hospitalized patients with different outcomes for nosocomial staphylococcal infections could be extremely useful for the evaluation of candidate vaccine antigens in addition to protection data generated with animal models.     

Role of endogenous cannabinoids in synaptic signaling

Research of cannabinoid actions was boosted in the 1990s by remarkable discoveries including identification of endogenous compounds with cannabimimetic activity (endocannabinoids) and the cloning of their molecular targets, the CB1 and CB2 receptors. Although the existence of an endogenous cannabinoid signaling system has been established for a decade, its physiological roles have just begun to unfold. In addition, the behavioral effects of exogenous cannabinoids such as delta-9-tetrahydrocannabinol, the major active compound of hashish and marijuana, await explanation at the cellular and network levels. Recent physiological, pharmacological, and high-resolution anatomical studies provided evidence that the major physiological effect of cannabinoids is the regulation of neurotransmitter release via activation of presynaptic CB1 receptors located on distinct types of axon terminals throughout the brain. Subsequent discoveries shed light on the functional consequences of this localization by demonstrating the involvement of endocannabinoids in retrograde signaling at GABAergic and glutamatergic synapses. In this review, we aim to synthesize recent progress in our understanding of the physiological roles of endocannabinoids in the brain. First, the synthetic pathways of endocannabinoids are discussed, along with the putative mechanisms of their release, uptake, and degradation. The fine-grain anatomical distribution of the neuronal cannabinoid receptor CB1 is described in most brain areas, emphasizing its general presynaptic localization and role in controlling neurotransmitter release. Finally, the possible functions of endocannabinoids as retrograde synaptic signal molecules are discussed in relation to synaptic plasticity and network activity patterns.     

Effect of timing of oocyte denudation and micro-injection on survival, fertilization and embryo quality after intracytoplasmic sperm injection

In human in-vitro fertilization (IVF), the oocytes are surrounded by cumulus and corona cells at the time of insemination so that their maturity cannot easily be evaluated. The best IVF results are obtained if the oocytes are inseminated 2-6 h after retrieval. In the intracytoplasmic sperm injection (ICSI) procedure, the oocytes are denuded by enzymatic and mechanical treatment in order to be able to perform the injection. As a consequence, the nuclear maturity of the oocytes can be evaluated and only those that have extruded the first polar body are injected. However, metaphase-II oocytes that have not yet reached cytoplasmic maturity cannot be recognized. The purpose of this study was to investigate the effect of different timing of cumulus- corona cell removal and injection on the outcome of ICSI. For this we allowed the oocytes to complete in-vitro cytoplasmic maturation in two different culture conditions: (i) surrounded by their cumulus and corona cells or (ii) totally denuded. We performed three different studies on sibling oocytes obtained after a standardized buserelin/human menopausal gonadotrophin (HMG) protocol. We investigated the effect of early (1-2 h after retrieval) and late (5-6 h after retrieval) oocyte denudation and injection on the survival and fertilization of the injected oocytes and on embryo cleavage after fertilization. We found no statistically significant differences between early and late injection, indicating that after a standardized buserelin/HMG protocol the metaphase-II oocytes do not need time for further cytoplasmic maturation. Furthermore, a different timing of cumulus-corona cell removal has no effect on the outcome of ICSI, suggesting that the surrounding cells are not necessary for survival, fertilization and cleavage after ICSI.      

Ser80Ile mutation and a concurrent Pro25Leu variant of the <Emphasis Type="Italic">VHL</Emphasis> gene in an extended Hungarian von Hippel-Lindau family

Von Hippel-Lindau disease (VHL) is a rare autosomal dominant disease characterized by development of cystic and tumorous lesions at multiple sites, including the brain, spinal cord, kidneys, adrenals, pancreas, epididymis and eyes. The clinical phenotype results from molecular abnormalities of the VHL tumor suppressor gene, mapped to human chromosome 3p25-26. The VHL gene encodes two functionally active VHL proteins due to the presence of two translational initiation sites separated by 53 codons. The majority of disease-causing mutations have been detected downstream of the second translational initiation site, but there are conflicting data as to whether few mutations located in the first 53 codons, such as the Pro25Leu could have a pathogenic role. In this paper we report a large Hungarian VHL type 2 family consisting of 32 members in whom a disease-causing AGT80AAT (Ser80Ile) c.239G>A, p.Ser80Ile mutation, but not the concurrent CCT25CTT (Pro25Leu) c.74C>T, p.Pro25Leu variant co-segregated with the disease. To our knowledge, the Ser80Ile mutation has not been previously described in VHL type 2 patients with high risk of pheochromocytoma and renal cell cancer. Therefore, this finding represents a novel genotype-phenotype association and VHL kindreds with Ser80Ile mutation will require careful surveillance for pheochromocytoma. We concluded that the Pro25Leu variant is a rare, neutral variant, but the presence such a rare gene variant may make genetic counseling difficult.     

Interpretation of gram-stained sputa containing Moraxella (Branhamella) catarrhalis.

Sputum specimens culture positive for Moraxella (Branhamella) catarrhalis were Gram stained with three decolorizer solutions (slow, 95% ethyl alcohol; intermediate, 1:1 ratio of 95% ethyl alcohol and acetone; and fast, acetone alone) for 5, 10, 20, and 30 s. Optimal results were obtained with acetone alone after 10 s or with a 1:1 mixture of acetone and ethanol after 20 s. Inadequate decolorization of M. catarrhalis in sputa is likely if the decolorization solution and exposure time are not optimal and may contribute to underreporting of this organism.