Sucrose esters from the fruits of Physalis nicandroides var. attenuata

Three 2,3,1',3'-tetraacyl- and two 2,3,3'-triacylsucroses, nicandroses A-E (1-5), were isolated from the fruits of Physalis nicandroides var. attenuata. The acyl groups in these new compounds were identified as decanoyl, isobutyryl, 2-methylbutanoyl, and acetyl. The structures of 1-5 were determined on the basis of NMR and MS analyses.     

Labdanes and withanolides from Physalis coztomatl

Aerial parts of Physalis coztomatl afforded a new labdane diterpene, physacoztomatin (1), and five new withanolides, physacoztolides A-E (5-9). Six known compounds were also isolated. The structures of the new compounds were established after analyses of their spectroscopic data and by means of chemical transformations. X-ray diffraction analyses of 15-dehydrophysacoztomatin (2) and 5 confirmed the structures of 1 and 5. Labd-13(E)-ene-8alpha,15-diol (4) and physacoztomatin (1) represent the first labdane diterpenes isolated from the genus Physalis.     

In vitro validation of duct differentiation in developing embryonic mouse pancreas

BACKGROUND: Early embryonic pancreatic epithelia have the capacity for either endocrine or exocrine lineage commitment. Recent studies demonstrated the pluripotential nature of these undifferentiated cells. Isolated pancreatic epithelia grown under the renal capsule formed primarily islets. However, when these same epithelia were grown in a basement-membrane-rich gel (Matrigel) they formed mostly ducts. Currently, there is no model for in vitro pancreatic duct formation and therefore, the mechanism of duct morphogenesis has never been described. The purpose of this study was to provide such a model by characterizing the expression of two duct markers, carbonic anhydrase II (CAII) and the cystic fibrosis transmembrane conductance regulator (CFTR), in isolated undifferentiated pancreatic epithelia grown in vitro. MATERIALS AND METHODS: We microdissected embryonic pancreases at Embryonic Days (E)9.5-11.5 and performed RT-PCR for CAII and CFTR on E9.5 whole pancreases, E10. 5 and E11.5 epithelia, as well as E11.5 epithelia grown for 7 days in Matrigel. Next we performed in situ hybridization for CAII and CFTR and immunohistochemistry for CAII on E11.5 epithelia grown for 7 days in Matrigel. RESULTS: Early, undifferentiated embryonic pancreatic epithelium does not express CAII and CFTR by RT-PCR. When E11.5 epithelia were grown for 7 days in Matrigel, however, gene expression for both markers is upregulated as ducts form. Furthermore, CAII was seen by IHC and both CAII and CFTR were seen by in situ hybridization in the ducts after 7 days in Matrigel. CONCLUSIONS: These data validate our in vitro system as a model for studying the mechanism of normal pancreatic duct differentiation and may potentially help us to understand the faulty mechanism involved in pancreatic ductal carcinogenesis.     

Dynamics of striate cortical activity in the alert macaque: I. Incidence and stimulus-dependence of gamma-band neuronal oscillations

Using single and multiunit recordings in the striate cortex of alert macaque monkeys, we find that gamma-band (20-70 Hz) oscillations in neuronal firing are a prominent feature of V1 neuronal activity. The properties of this rhythmic activity are very similar to those previously observed in the cat. Gamma-band activity is strongly dependent on visual stimulation, largely absent during spontaneous activity and, under the conditions of our experiment, not time-locked to the vertical refresh of the computer monitor (80 Hz) used to present the stimuli. In our sample, 61% of multiunit activity (MUA) and 46% of single-unit activity (SUA) was significantly oscillatory, with mean frequencies of 48+/-9 and 42+/-13 Hz, respectively. Gamma-band activity was most likely to occur when cells were activated by their optimal stimuli, but still occurred, although less often and with lower amplitude, in response to nonoptimal stimuli. The frequency of gamma-band activity also reflected stimulus properties, with drifting gratings evoking higher-frequency oscillations than stationary gratings. As in the cat, the spike trains of single cells showing gamma-band oscillations often displayed a pattern of repetitive burst firing, with intraburst firing rates of 300-800 Hz. The overall similarity of rhythmic neuronal activity in the primary visual cortex of cats and monkeys suggests that the phenomenon is not species-specific. The stimulus-dependence of the rhythmic activity is consistent with a functional role in visual perception.     

Evaluation of the tuberculin reaction in health occupation students] .

A cross-sectional study was done at the University of Antioquia, MedellIn, Colombia, to evaluate the response to a tuberculin skin test among students in undergraduate health programs (medicine, odontology, nursing, and bacteriology) as compared to undergraduate students in nonhealth programs. The study included students from the beginning, middle, and end of the university's academic programs. The sample of 490 students included 273 from health programs and 217 from nonhealth programs. Participants were randomly selected using lists provided by the university registrar, for the second semester of 1998. The presence of a BCG vaccination scar was determined, and all the participants were also questioned about TB-related risk factors. Tuberculin skin test reactivity was evaluated by the size of induration 72 hours after intradermal injection of two tuberculin units of purified protein derivative RT 23. There were no differences in tuberculin reactivity between students from the health programs and from the nonhealth programs, irrespective of the academic level. However, there was a significantly higher proportion of positive skin tests among students with a BCG scar. These results suggest that undergraduate health students do not have extensive contact with TB patients or with clinical samples from such patients. Nevertheless, the results do not rule out TB as an occupational risk for health personnel.     

Distribution of beta-amyloid and amyloid precursor protein in the brain of spawning (senescent) salmon: a natural, brain-aging model

Brain amyloid precursor protein (APP), a normal constituent of neurons, glial cells and cerebrospinal fluid, has several proposed functions (e.g., in neuronal growth and survival). It appears, however, that altered processing of APP is an initial or downstream step in the neuropathology of brain aging, Alzheimer's disease (AD), and Down's syndrome (DS). Some studies suggest that proteolytic cleavage of APP, producing beta-amyloid (Abeta(1-42)), could have neurotoxic or neuroprotective effects. In this study, we utilized antibodies to human APP(695) and Abeta(1-42,) and Congo red staining, to search for amyloid deposition in the brain of semelparous spawning kokanee salmon (Oncorhynchus nerka kennerlyi). Intracellular APP(695) immunoreactivity (APP-ir) was observed in brain regions involved in gustation (glomerulosus complex), olfaction (putative hippocampus, olfactory bulb), vision (optic tectum), the stress response (nucleus preopticus and nucleus lateralis tuberis), reproductive behavior (nucleus preopticus magnocellularis, nucleus preopticus periventricularis, ventral telencephalon), and coordination (cerebellum). Intra- and extra-neuronal Abeta(1-42) immunoreactivity (Abeta-ir) were present in all APP-ir regions except the nucleus lateralis tuberis and Purkinje cells of the cerebellum (coordination). Thus, the relationship between APP and Abeta deposition during brain aging could shed light on the processing of APP into Abeta, neurodegeneration, and possible protection of neurons that are functioning in spawning but senescent salmon. Pacific salmon, with their predictable and synchronized life history, could provide research options not available with the existing models for studies of brain aging and amyloidosis.     

Effect of quinolinic acid on endogenous antioxidants in rat corpus striatum

The response of endogenous antioxidants to the N-methyl-D-aspartate (NMDA) receptor agonist and excitotoxin, quinolinic acid (QUIN), was investigated in rat corpus striatum. Animals treated with QUIN (240 nmol/microl), were sacrificed at 120 min after a single intrastriatal injection to examine the alterations in the levels of both reduced (GSH) and oxidized (GSSG) glutathione, and the activities of the antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (Gpx). Changes in the rate of lipid peroxidation (LP) were also measured after exposure to different doses of QUIN (60, 120, 240 and 480 nmol/microl) as an index of oxidative stress. When compared to control, lipid peroxidation was increased at QUIN doses of 240 and 480 nmol/microl. Striatal levels of GSH and GSSG were decreased and increased, respectively, after QUIN injection; whereas GPx activity was unchanged. Cytosolic copper/zinc SOD (CuZn-SOD) activity decreased after treatment, while mitochondrial manganese SOD (Mn-SOD) was unchanged. The alterations observed on these antioxidant systems suggest that QUIN toxicity is mediated by specific mechanisms leading to oxidative stress.     

Cannabinoid withdrawal is dependent upon PKA activation in the cerebellum

Region-specific up-regulation of the cyclic AMP pathway is considered an important molecular mechanism in the origin of the somatic manifestations of the withdrawal syndrome to known drugs of abuse. Nevertheless, the existence of a withdrawal syndrome after prolonged cannabinoid administration has long been a controversial issue. Recent studies, in different species, have shown that withdrawal to prolonged cannabinoid exposure precipitated by the cannabinoid antagonist SR141716A is characterized by physical signs underlying impairment of motor coordination. Interestingly, cannabinoid withdrawal is accompanied by an increase of adenylyl cyclase activity in the cerebellum. Here, we investigate the functional role of the cyclic AMP pathway in the cerebellum in the establishment of cannabinoid withdrawal. We show that after SR141716A precipitation of cannabinoid withdrawal, basal and calcium-calmodulin-stimulated adenylyl cyclase activities as well as active PKA in the cerebellum increase in a transient manner with a temporal profile which matches that of the somatic expression of abstinence. Selectively blocking the up-regulation of the cyclic AMP pathway in the cerebellum, by microinfusing the cyclic AMP blocker Rp-8Br-cAMPS in this region, markedly reduced both PKA activation and the somatic expression of cannabinoid withdrawal. Our results (i) directly link the behavioural manifestations of cannabinoid withdrawal with the up-regulation of the cyclic AMP pathway in the cerebellum, pointing towards common molecular adaptive mechanisms for dependence and withdrawal to most drugs of abuse; (ii) suggest a particular role for the cerebellum as a major neurobiological substrate for cannabinoid withdrawal.