Influence of nitric oxide synthase activity on amino acid concentration in the quinolinate lesioned rat striatum: A microdialysis and histochemical study

Summary. The influence of nitric oxide synthase (NOS) activity on the KCl-evoked amino acid concentrations was investigated by in vivo microdialysis in the striatum in a rat model of excitotoxic lesion. Basal microdialysate levels of amino acids decreased during the quinolinic acid-induced neurodegeneration process, except for glutamine that increased initially and returned to control values 30 days after quinolinic acid exposure. KCl-evoked increase of extracellular amino acid concentration was reduced due to NOS activity in the striatum of both controls and lesioned animals, except for 120 days after quinolinic acid injection. These changes of amino acid concentrations in microdialysates correlated with the known biochemistry of the consecutive domineered cell types during the lesion process as revealed by histochemistry for NOS, NADPH-diaphorase, GFAP and isolectin B4. The present data provide direct evidence that NOS activity can modulate extracellular amino acid concentrations in the striatum not only under physiological conditions, but also during a pharmacologically induced lesion process and, thus, suggests that nitric oxide affects neurodegeneration via this pathway. Received October 20, 1999; Accepted February 25, 2000     

The glycosphingolipid sulfatide in the islets of Langerhans in rat pancreas is processed through recycling: possible involvement in insulin trafficking

In previous studies we have shown that sulfatide (galactosylceramide-3-O-sulfate), in various species, is present in the insulin-producing cells in pancreatic islets of Langerhans. In this study the synthesis of sulfatide in the islets has been investigated by pulse chase labeling at varying glucose levels and in the presence or absence of the glycosphingolipid synthesis inhibitory agents, Brefeldin A, fumonisin B1 and chloroquine and the distribution of sulfatide by immune-electronmicroscopy. The data showed that (1) sulfatide was produced in islets of Langerhans, (2) the main pathway for synthesis was through recycling involving partial degradation in the lysosome, and that (3) high glucose levels, although not primarily reflected in an increased synthesis of sulfatide, lead to an increased expression of mRNA for the UDP-galactose:ceramide galactosyltransferase, producing the immediate precursor of sulfatide. Furthermore, mass spectrometry analyses revealed a high proportion of short chain fatty acids, C16:0 (50%) and no hydroxylated forms and thus special physicochemical properties, indicating important differences between pancreatic and brain/neural sulfatide. Immune electron microscopy revealed an intracellular expression of sulfatide in the secretory granules, the Golgi network and the lysosomes of the islets. These results indicate that sulfatide follows the same intracellular route as insulin and suggest a functional association between these molecules. We have raised the hypothesis that sulfatide possibly plays a role in the trafficking of insulin in the islets of Langerhans in rat pancreas.     

Cargo binding and regulatory sites in the tail of fungal conventional kinesin

Here, using a quantitative in vivo assay, we map three regions in the carboxy terminus of conventional kinesin that are involved in cargo association, folding and regulation, respectively. Using C-terminal and internal deletions, point mutations, localization studies, and an engineered 'minimal' kinesin, we identify five heptads of a coiled-coil domain in the kinesin tail that are necessary and sufficient for cargo association. Mutational analysis and in vitro ATPase assays highlight a conserved motif in the globular tail that is involved in regulation of the motor domain; a region preceding this motif participates in folding. Although these sites are spatially and functionally distinct, they probably cooperate during activation of the motor for cargo transport.     

Predictive value of DNA cytometry in CIN 1 and 2. Image analysis of 193 cases

OBJECTIVE: To investigate DNA image cytometry for predicting the prognosis of cervical intraepithelial neoplasia (CIN). STUDY DESIGN: Smears from 151 women affected by CIN 1 or 2 on cytology with minimal follow-up of three years were included. Sixty-seven showed progression, with histologically confirmed carcinoma in situ or invasive cancer. Eighty-four cases showed regression of the disease, which was cytologically, histologically and colposcopically confirmed. Papanicolaou-stained smears were destained, and the Feulgen reaction was performed with consecutive image DNA cytometry of suspicious cells using an image analysis system (Cires, Zeiss, Germany). The DNA index of the greatest stemline and the number of single aneuploid cells, using 9c exceeding events, were computed. RESULTS: In the group with progression, an aneuploid DNA stemline was found in 25 smears (26.9%). In 64 cases (66.7%) more than one aneuploid event was detected. The total number of aneuploid cases in this group was 76 (81%). In the group without progression, the number of aneuploid stemlines was 2 (2%). Single aneuploid cells could be found in five cases (5%). The overall number of aneuploid cases in that group was five. The sensitivity was 74.3%, positive predictive value 85.2% and negative predictive value 77%. CONCLUSION: Aneuploidy is a marker for prospective malignancy in cervical Papanicolaou smears. DNA image cytometry, as an additional method, can be used to predict outcome in patients with CIN 1 and 2 of the cervix. DNA cytometry is not a screening method but can add further information for a treatment decision in doubtful cases.     

Influence of baking enzymes on antimicrobial activity of five bacteriocin‐like inhibitory substances produced by lactic acid bacteria isolated from Lithuanian sourdoughs

Aim: To evaluate the effect of four different baking enzymes on the inhibitory activity of five bacteriocin‐like inhibitory substances (BLIS) produced by lactic acid bacteria (LAB) isolated from Lithuanian sourdoughs. Methods and Results: The overlay assay and the Bioscreen methods revealed that the five BLIS exhibited an inhibitory effect against spore germination and vegetative outgrowth of Bacillus subtilis, the predominant species causing ropiness in bread. The possibility that the observed antibacterial activity of BLIS might be lost after treatment with enzymes used for baking purposes was also examined. Conclusions: The enzymes tested; hemicellulase, lipase, amyloglucosidase and amylase had little or no effect on the majority of the antimicrobial activities associated with the five BLIS studied. Significance and Impact of the Study: This study suggests a potential application in the sourdough baking industry for these antimicrobial producing LAB strains in the control of B. subtilis spore germination and vegetative outgrowth.     

Evidence that ATP-dependent Ca2+ transport in rat parotid microsomal membranes requires charge compensation.

ATP-dependent Ca2+ transport was investigated in a rat parotid microsomal-membrane preparation enriched in endoplasmic reticulum. Ca2+ uptake, in KCl medium, was rapid, linear with time up to 20 s, and unaffected by the mitochondrial inhibitors NaN3 and oligomycin. This Ca2+ uptake followed Michaelis-Menten kinetics, and was of high affinity (Km approximately 38 nM) and high capacity (approximately 30 nmol/min per mg of protein). In the presence of oxalate, Ca2+ uptake continued to increase for at least 5 min, reaching an intravesicular accumulation approx. 10 times higher than without oxalate. Ca2+ uptake was dependent on univalent cations in the order K+ = Na+ greater than trimethylammonium+ greater than mannitol and univalent anions in the order Cl- greater than acetate- greater than Br- = gluconate- = NO3- greater than SCN-. Ca2+ uptake was not elevated if membranes were incubated in the presence of a lipophilic anion (NO3-) and carbonyl cyanide p-trifluoromethoxyphenylhydrazone. Ca2+ transport was altered by changes in the K+-diffusion potential of the membranes. A relatively negative K+-diffusion potential increased the initial rate of Ca2+ accumulation, whereas a relatively positive potential decreased Ca2+ accumulation. In the presence of an outwardly directed K+ gradient, nigericin had no effect on Ca2+ uptake. In aggregate, these studies suggest that the ATP-dependent Ca2+-transport mechanism present in rat parotid microsomal membranes exhibits an electrogenic Ca2+ flux which requires the movement of other ions for charge compensation.