EEG correlates of spatial orientation in the human retrosplenial complex.

Studies on spatial navigation reliably demonstrate that the retrosplenial complex (RSC) plays a pivotal role for allocentric spatial information processing by transforming egocentric and allocentric spatial information into the respective other spatial reference frame (SRF). While more and more imaging studies investigate the role of the RSC in spatial tasks, high temporal resolution measures such as electroencephalography (EEG) are missing. To investigate the function of the RSC in spatial navigation with high temporal resolution we used EEG to analyze spectral perturbations during navigation based on allocentric and egocentric SRF. Participants performed a path integration task in a clearly structured virtual environment providing allothetic information. Continuous EEG recordings were decomposed by independent component analysis (ICA) with subsequent source reconstruction of independent time source series using equivalent dipole modeling. Time-frequency transformation was used to investigate reference frame-specific orientation processes during navigation as compared to a control condition with identical visual input but no orientation task. Our results demonstrate that navigation based on an egocentric reference frame recruited a network including the parietal, motor, and occipital cortices with dominant perturbations in the alpha band and theta modulation in frontal cortex. Allocentric navigation was accompanied by performance-related desynchronization of the 8-13 Hz frequency band and synchronization in the 12-14 Hz band in the RSC. The results support the claim that the retrosplenial complex is central to translating egocentric spatial information into allocentric reference frames. Modulations in different frequencies with different time courses in the RSC further provide first evidence of two distinct neural processes reflecting translation of spatial information based on distinct reference frames and the computation of heading changes.

Determination of Au and Pt in titanate nanotube catalysts by photon activation analysis.

This study demonstrated the determination of Au and Pt concentrations in titanate nanotube-supported (abbreviated as TNT-supported) metal catalysts by photon activation and their catalytic activity with respect to metal concentration. An 18MV medical accelerator was used as photon source to activate the metals and generate radionuclides for gamma-ray spectroscopic analysis. Two TNT-supported metal catalysts, namely Au/NaTNT and Pt/MTNT (M=Na(+) and Cs(+)), were prepared and the Au and Pt concentrations and the respective loading efficiencies were determined. The detection sensitivities with respect to the photon activated radionuclides were estimated to select the most sensitive gamma rays for the determination of Au and Pt concentrations. The loading efficiency for Au/NaTNT decreased with increasing Au concentration prepared, while it was almost 100% for Pt loading in Pt/MTNT of various prepared Pt concentrations. The Au/NaTNT containing 2.53 wt% of Au effectively oxidized CO at a much lower reaction temperature than the lower concentration ones. For cinnamaldehyde hydrogenation reaction, the catalytic activity of Pt/TNT with different Pt loadings followed the order of 2.9>2.3>0.9>0.5 wt%. This photon activation technique, with minus interfering radionuclides in the gamma-ray spectra and induced radioactivities in the samples, is perfectly suited to the determination of metal concentrations in TNT-supported catalysts, that might contain considerable amounts of alkali metal ions.

Maximization of injection volumes for DNA analysis in capillary electrophoresis.

We report concentration and separation of DNA in the presence of electroosmotic flow (EOF) using poly(ethylene oxide) (PEO) solution. DNA fragments migrating against EOF stacked between the sample zone and PEO solution. To maximize the injection volume, several factors, such as concentrations of Tris-borate (TB) buffer and PEO solution, capillary size, and matrix, were carefully evaluated. The use of 25 mM TB buffers, pH 10.0, containing suitable amounts (less than 10 mM) of salts, such as sodium chloride, sodium phosphate, and sodium acetate, to prepare DNA is essential for the concentration of large-volume samples. In the presence of salts, the peaks also became sharper and the fluorescence intensity of DNA complexes increased. Using 2.5% PEO and a 150 microm capillary filled with 400 mM TB buffer, pH 10.0, up to 5 microL DNA samples (phiX 174 RF DNA-HaeIII digest or the mixture of pBR 322/HaeIII, pBR 328/Bg/I, and pBR 328/HinfI digests) have been analyzed, resulting in more than 400-fold improvements in the sensitivity compared to that by conventional injections (ca. 36 nL). Moreover, this method allows the analysis of 3.5 microL PCR products amplified after 17 cycles without any sample pretreatment.

Follicular arrest during the midfollicular phase of the menstrual cycle: a gonadotropin-releasing hormone antagonist imposed follicular-follicular transition.

The functional dependency of the dominant follicle on pulsatile gonadotropin inputs was evaluated by using a GnRH antagonist as a probe. Hormonal dynamics, particularly the relationship of FSH, estradiol, and inhibin, during and after the withdrawal of GnRH receptor blockade achieved by treatment with Nal-Glu GnRH antagonist (50 micrograms/kg, im) for 3 days in the midfollicular phase of the cycle (days 7-9) were ascertained. Daily blood samples were obtained for LH, FSH, estradiol (E2), progesterone, and immunoreactive inhibin (i-INH) measurements by RIA during 2 consecutive (control and treatment) cycles in 12 women. In 5 women, LH pulsatility was assessed by 10-min blood sampling for 12 h before, during, and after Nal-Glu treatment. The administration of Nal-Glu prolonged both follicular phase (14.0 +/- 0.5 vs. 19.7 +/- 0.8 days; P less than 0.0001) and total cycle length (28.1 +/- 0.5 vs. 34.1 +/- 1.2 days; P less than 0.0001). Gonadotropin suppression (50-60%) was achieved, as reflected by a marked decrease in mean LH levels (14.3 +/- 1.9 to 5.4 +/- 0.5; P less than 0.01) and LH pulse amplitude (5.5 +/- 0.7 to 2.4 +/- 0.3 IU/L; P less than 0.01) in response to Nal-Glu antagonist. The number of LH pulses was reduced (36%), but pulses remained discernible. Concentrations of FSH (10.8 +/- 1.4 to 5.9 +/- 0.4 IU/L; P less than 0.05), E2 (322.7 +/- 71.9 to 84.8 +/- 7.7 pmol/L; P less than 0.01) and i-INH (284.0 +/- 25.9 to 164.4 +/- 7.5 U/L; P less than 0.01) decreased concomitantly. Within 24-48 h of the last injection of Nal-Glu, all hormones had returned to pretreatment levels. This was followed by normal functional expression of follicular growth and maturation, as reflected by an increase in E2 and i-INH levels, timely ovulation, and normal luteal function. These findings indicate that an approximately 50% decline in gonadotropin support to the dominant follicle leads to functional arrest, but not demise, of the developing follicle(s) without triggering new folliculogenesis. The follicular apparatus retained its ability to reinitiate its original functionality once appropriate gonadotropin inputs were reinstated.

Diverticulitis of the midrectum.

Diverticulitis of the rectum is a rare condition. This report covers patient history, diagnosis, and treatment involved in such a case. The patient presented with a history of rectal pain and muscle spasm of six months' duration. After several available examinations had been completed, i.e., digital examination, sigmoidoscopy, and barium-enema examination, the diagnosis of a rectal diverticulum was made. Initially, conservative treatment, including high-fiber diet and sitz baths, proved effective. Approximately nine months later, the patient developed severe rectal pain, unrelieved by previously effective measures. After the above-described examinations had been repeated, the rectal wall was found to be ulcerated and inflamed, and a diagnosis of diverticulitis of the rectum was made. Antibiotic therapy and evacuation of the 3- to 4-cm mass under anesthesia resulted in subsidence of symptoms and resolution of the mass. Segmental resection will be considered if the diverticulum becomes infected again.

Multiple molecular forms of glia maturation factor.

Glia maturation factor from the pig brain can be detected in two molecular forms: the high molecular weight form which is 200 000 dalton in size and the low molecular weight form which is 40 000 dalton in size, as determined by Sephadex gel filtration. The former accounts for 85% of the total biological activity extracted at physiologic pH. The proportion of the low molecular weight form increases following freeze-thawing and ion-exchange chromatography. In addition to the morphological effects, both forms possess mitogenic activity but no esteropeptidase activity. Both forms show similar enzyme susceptibility, being inactivated by papain, ficin and pronase but resistant to subtilisin, thermolysin and trypsin. The high molecular weight form is more resistant to denaturation by low pH, heating and urea than the low molecular weight form. The high molecular weight factor has an isoelectric point of 4.27 whereas the low molecular weight factor has one of 5.04.

Survey of Salmonellae in mesenteric lymph nodes, gallbladder wall and jejunum from healthy pigs slaughtered in Taiwan.

A study made in Taiwan showed that 23.3 per cent of healthy slaughter pigs were infected with salmonellae. Samples of gallbladder wall/liver, mesenteric lymph nodes and jejunum wall were found to yield salmonellae in 16.4, 5.2 and 11.6 per cent of cases respectively. Salmonellae isolated belonged to nine different serotypes, S. london being the serotype most frequently isolated (26.8%) followed by S. anatum, S. panama (16.1% each) and S. typhimurium (12.5%). Of the total number of salmonellae isolated 68.5 per cent were detected simultaneously on brilliant-green phenol-red lactose sucrose agar (BGA) and desoxycholate agar (DCA), whilst 18.5 per cent were detected only on DCA and 13 per cent only on BGA plates.

Topography of glycoproteins in the chick synaptosomal plasma membrane.

Chick brain synaptosomes or synaptic subfractions were treated with neuraminidase (EC 3.2.1.18) and/or galactose oxidase (EC 1.1.3.9) preparations in which proteolytic activity was inhibited with phenylmethanesulfonyl fluoride followed, after washing, by reductive incorporation of sodium boro[3H]hydride to identify galactose residues exposed on the synaptosomal external surface. Control experiments to demonstrate restriction of labeling to the external surface involved comparing the radioactivity in synaptoplasmic, soluble polypeptides isolated after labeled, isolated synaptoplasm and examining incorporation into fractions incubated without enzymes. Intactness of the synaptic plasma membrane after labeling was shown by trypsin digestion studies. Polypeptides were separated on sodium dodecyl sulfate polyacrylamide gels and were detected by a liquid scintillation counting procedure. Eleven major radioactive peaks were found after galactose oxidase treatment and reduction of isolated synaptic membranes. When intact synaptosomes were labeled, the same components were detected. When isolated synaptic membranes or intact synaptosomes were treated with neuraminidase before galactose oxidase treatment, three additional components were labeled. These results suggest that (a) chick synaptic membranes have a complex mixture of glycoproteins, (b) all major chick synaptic membrane glycoproteins labeled by galactose oxidase have most or all carbohydrate groups exposed at the exterior surface of the synaptosome, (c) all major, externally-disposed polypeptides of these synaptic membranes are glycoproteins.

On using cis-Pt (II)-uracil as a stain for nucleic acids in brain slices and subcellular fractions.

Chick brain cortical slices and crude mitochondrial fractions were fixed with glutaraldehyde, stained only with cis-Pt (II)-uracil and processed for electron microscopy. The optimal time of staining was determined to be 10 min. Results show that this platinum-pyrimidine complex is a relatively specific stain for the nucleic acids of brain slices. However, staining of crude mitochondrial fractions apparently resulted in some protein staining and other artifacts. The method should be helpful identifying ribosomal contamination of subcellular preparations and if its specificity can be increased it may prove a useful addition to staining methods of the electron microscopist.

Preparation of chick brain synaptosomes and synaptosomal membranes.

A method is described for the preparation of synaptosomes and synaptosomal membranes from chicken brain. Procedures for isolating rat synaptosomal membranes could not be used directly; several modifications of existing procedures are reported. Purity of the subcellular and subsynaptosomal fractions was monitored by electron microscopy and measurements of ferrocytochrome c: oxygen oxidoreductase (EC 1.9.3.)), monoamine: oxygen oxidoreductase (deaminating) EC 1.4.3.4), rotenone-insensitive NADH: cytochrome c oxidoreductase (EC 1.6.99.3), NADPH: cytochrome c oxidoreductase (EC 1.6.99.1), orthophosphoric monoester phosphohydrolase (EC 3.1.3.2), ATP phosphohydrolase (EC 3.6.1.4), and levels of RNA. Microsomes are the main contaminant of the synaptosomal membrane fraction. Mitochondrial and lysosomal enzymes occur in lesser amounts. No myelin contamination was observed. Marker enzymes for contaminants suggest that these synaptosomal membranes are as pure as membranes described by others, and the specific activity of a neuronal membrane marker, (Na+ -K+)-activated ATPase, is as high as other preparations. Levels of this enzyme in the membrane fraction are enriched 13-fold over homogenate ATPase levels.