Brainstem application of melanocortin receptor ligands produces long-lasting effects on feeding and body weight

Recent evidence suggests that the central melanocortin (MC) system is a prominent contributor to food intake and body weight control. MC receptor (MC-R) populations in the arcuate and paraventricular nuclei are considered probable sites of action mediating the orexigenic effects of systemically or intracerebroventricularly administered ligands. Yet, the highest MC4-R density in the brain is found in the dorsal motor nucleus of the vagus nerve, situated subjacent to the commissural nucleus of the solitary tract, a site of pro-opiomelanocortin mRNA expression. We evaluated the contribution of the caudal brainstem MC system by (1) performing respective dose-response analyses for an MC-R agonist (MTII) and antagonist (SHU9119) delivered to the fourth ventricle, (2) comparing, in the same rats, the fourth intracerebroventricular dose-response profiles to those obtained with lateral intracerebroventricular delivery, and (3) delivering an effective dose of MTII or SHU9119 to rats before a 24 hr period of food deprivation. Fourth intracerebroventricular agonist treatment yielded a dose-dependent reduction of short-term (2 and 4 hr) and longer-term (24 hr) food intake and body weight. Fourth intracerebroventricular antagonist treatment produced the opposite pattern of results: dose-related increases in food intake and corresponding increases in body weight change for the 24-96 hr observation period. Comparable dose-response functions for food intake and body weight were observed when these compounds were delivered to the lateral ventricle. Results from deprived rats (no effect of MTII or SHU9119 on weight loss) support the impression derived from the dose-response analyses that the body weight change that follows MC treatments is secondary to their respective effects on food intake. Results support the relevance of the brainstem MC-R complement to the control of feeding.     

Management of infections due to antibiotic-resistant Streptococcus pneumoniae

Antibiotic-resistant strains of Streptococcus pneumoniae are becoming more prevalent throughout the world; this has resulted in modifications of treatment approaches. Management of bacterial meningitis has the greatest consensus. Strategies for treating other systemic infections such as pneumonia, bacteremia, and musculoskeletal infections are evolving, in part related to the availability of new antibiotics which are active in vitro against isolates resistant to penicillin and the extended-spectrum cephalosporins. However, there are currently very limited data related to the clinical efficacy of these new agents. The studies upon which current recommendations are based are reviewed. Otitis media represents the single most common infection due to S. pneumoniae. Recommendations for treatment of acute otitis media due to drug-resistant strains and the rationale for these recommendations are discussed.     

Spontaneous resolution of nonimmune hydrops in a fetus with a cystic adenomatoid malformation

BACKGROUND: Blood bank recommendations specify that Ringer's lactate solution (LR) should be avoided while transfusing blood. However, there are few studies either evaluating or quantifying increased coagulation during rapid infusion of LR and blood. DESIGN AND METHODS: Whole blood (WB, n = 25) and packed red blood cells (PRBC, n = 26) were rapidly admixed with normal saline (NS), Lactate solution and LR with 1 g (LR-1), 2 g (LR-2), and 5 g (LR-5) CaCl2/L solutions for assessment of infusion time, filter weight, and clot formation. RESULTS: No significant differences in infusion time or filter weight using WB or PRBC with NS or LR were seen. No significant difference in clot formation between NS and LR with WB or PRBC was found, but the presence of visible clot was increased in the LR-5 group (P = 0.013, WB, and P = 0.002, PRBC). CONCLUSION: A comparison of LR and NS with rapid infusion rates of blood showed no significant difference between infusion time, filter weight and clot formation. Blood bank guidelines should be revised to allow the use of LR in the rapid transfusion of PRBC.     

Changes in brain-derived neurotrophic factor immunoreactivity in rat dorsal root ganglia, spinal cord, and gracile nuclei following cut or crush injuries

In the present study, we evaluated changes in brain-derived neurotrophic factor (BDNF) immunoreactivity in the rat lumbar (L) 5 dorsal root ganglion (DRG) and areas where afferents from the DRG terminate, the L5 spinal cord and gracile nuclei, following unilateral sciatic nerve transection or crush. From 3 days to 4 weeks following cut or crush injury, the percentage of medium and large BDNF-immunoreactive neurons in the ipsilateral DRG increased significantly compared with those on the contralateral side. Following cut injury, there was no significant change in the percentage of small BDNF-immunoreactive neurons in the ipsilateral DRG; however, the intensity of immunoreactivity of these cells decreased. Following crush injury, however, both the percentage and intensity of small BDNF-immunoreactive neurons in the ipsilateral DRG significantly increased. Following cut injury, the expression of BDNF-immunoreactive axonal fibers decreased markedly in the ipsilateral superficial laminae of the L5 spinal cord and increased significantly in the ipsilateral deeper laminae of the spinal cord and gracile nuclei. Crush injury induced a marked increase in the expression of BDNF-immunoreactive axonal fibers in the superficial laminae of the spinal cord and gracile nuclei. These differences in BDNF response in the DRG and spinal cord after cut or crush injuries may reflect differences in trophic support to the injured DRG neurons and altered neuronal activity in the spinal cord and gracile nuclei following different types of peripheral nerve injury.     

Definition of natural T cell antigens with mimicry epitopes obtained from dedicated synthetic peptide libraries

Progress has recently been made in the use of synthetic peptide libraries for the identification of T cell-stimulating ligands. T cell epitopes identified from synthetic libraries are mimics of natural epitopes. Here we show how the mimicry epitopes obtained from synthetic peptide libraries enable unambiguous identification of natural T cell Ags. Synthetic peptide libraries were screened with Mycobacterium tuberculosis-reactive and -autoreactive T cell clones. In two cases, database homology searches with mimicry epitopes isolated from a dedicated synthetic peptide library allowed immediate identification of the natural antigenic protein. In two other cases, an amino acid pattern that reflected the epitope requirements of the T cell was determined by substitution and omission mixture analysis. Subsequently, the natural Ag was identified from databases using this refined pattern. This approach opens new perspectives for rapid and reliable Ag definition, representing a feasible alternative to the biochemical and genetic approaches described thus far.     

A prospective 12-year study of subsyndromal and syndromal depressive symptoms in unipolar major depressive disorders

BACKGROUND: Investigations of unipolar major depressive disorder (MDD) have focused primarily on major depressive episode remission/recovery and relapse/recurrence. This is the first prospective, naturalistic, long-term study of the weekly symptomatic course of MDD. METHODS: The weekly depressive symptoms of 431 patients with MDD seeking treatment at 5 academic centers were divided into 4 levels of severity: (1) depressive symptoms at the threshold for MDD; (2) depressive symptoms at the threshold for minor depressive or dysthymic disorder (MinD); (3) subsyndromal or subthreshold depressive symptoms (SSDs), below the thresholds for MinD and MDD; and (4) no depressive symptoms. The percentage of weeks at each level, number of changes in symptom level, and medication status were analyzed overall and for 3 subgroups defined by mood disorder history. RESULTS: Patients were symptomatically ill in 59% of weeks. Symptom levels changed frequently (1.8/y), and 9 of 10 patients spent weeks at 3 or 4 different levels during follow-up. The MinD (27%) and SSD (17%) symptom levels were more common than the MDD (15%) symptom level. Patients with double depression and recurrent depression had more chronic symptoms than patients with their first lifetime major depressive episode (72% and 65%, respectively, vs 46% of follow-up weeks). CONCLUSION: The long-term weekly course of unipolar MDD is dominated by prolonged symptomatic chronicity. Combined MinD and SSD level symptoms were about 3 times more common (43%) than MDD level symptoms (15%). The symptomatic course is dynamic and changeable, and MDD, MinD, and SSD symptom levels commonly alternate over time in the same patients as a symptomatic continuum of illness activity of a single clinical disease.     

Lac/Tet dual-inducible system functions in mammalian cell lines

The Escherichia coli Lac repressor (Lac system) and tetracycline responsive promoter (Tet system) systems have been used individually to regulate gene expression at the cellular as well as the organismal levels. In this study, these two systems were combined (designated Lac/Tet dual-inducible system) to regulate two inducible genes simultaneously in a single cell. The isopropyl-beta-D-thiogalactopyranoside (IPTG) and tetracycline (used for the operation of the Lac and the Tet systems) were non-cytotoxic to the cells when added together into the cells at around the optimal concentrations (IPTG: < or = 5 mM; tetracycline: < 1.5 micrograms). The rate and efficiency of induction and repression of two inducible genes regulated by the Lac/Tet dual-inducible system were similar to the results obtained when one inducible gene is regulated by one inducible system in a single cell. The Lac/Tet dual-inducible system could function in many cell lines, which was demonstrated by regulating the expression of beta-galactosidase and luciferase reporter genes in five tumor cell lines by transient transfection analysis. The feasibility of introducing a second inducible system into an already established inducible cell line was confirmed. Finally, we showed that the Lac/Tet dual-inducible system functions at translational and at functional levels in a stable cell line named 7-4-b, which contains the Ha-ras and bc1-2 inducible genes. In conclusion, this study extends the application of prokaryotic inducible systems from the regulation of a single gene to two genes and helps clarify the relationship between two genes and the effects of two genes on the cells.     

Stress protein expression in rat liver during tumour promotion: induction of heat-shock protein 27 in hepatocytes exposed to 2-acetylaminofluorene

Exposure of cells to a variety of stresses such as heat, radiation and xenobiotics leads to increased expression of heat-shock proteins (HSPs). HSPs protect cells against irreversible protein damage and are involved in adaptive responses to stress stimuli. Some HSPs are overexpressed in neoplasias, possibly contributing to the increased drug tolerance often observed in such lesions. We have studied HSP expression in two experimental rat hepatocarcinogenesis models. Our aim was to clarify whether they are involved in stress adaptation in hepatocytes during carcinogen exposure, and whether HSPs may contribute to xenobiotic resistance in preneoplastic lesions. The complete carcinogen 2-acetylaminofluorene (AAF) was used in a continuous feeding protocol, and in the resistant hepatocyte model where the growth of diethylnitrosamine initiated lesions is efficiently promoted. Of the HSPs tested, only heat-shock protein 27 (hsp27) was induced during continuous AAF exposure. After 4 weeks of feeding AAF, increased hsp27 expression was noted in hepatocytes in perivenous areas of the liver lobule, possibly mediating an adaptive response to stress caused by reactive AAF metabolites. Enzyme altered preneoplastic foci were not found to overexpress HSPs. Thus, HSP induction does not seem to be a general mechanism underlying the increased stress tolerance observed in such lesions.