Self-assembled monolayers of new dendron-thiols: manipulation of the patterned surface and wetting properties

SAMs based on a novel dendron-thiol system, which maintain the alkanethiols' active site, but with the -SH group connected to independently variable groups by a dendron-linker, showed a controllable surface pattern and wetting properties. The precisely tailored structure of dendron-thiols with locally controlled hydrophobic and hydrophilic peripheries allows the formation of designed surface structures on a gold surface, e.g. nano-stripes, honeycomb and homogeneous structures.

Neonatal exposure to a novel environment enhances the effects of corticosterone on neuronal excitability and plasticity in adult hippocampus

Electrophysiological studies have shown that activation of glucocorticoids receptors (GRs) influences neuronal excitability and activity dependent synaptic plasticity. In developmental studies, early life stimulation such as neonatal handling results in an up-regulation of glucocorticoid-receptor (GR) binding in the hippocampus that persists into adulthood. It is, therefore, hypothesized that early environment-induced changes in receptor sensitivity to corticosterone (CORT) might have functional effects on adult neuronal excitability and synaptic plasticity. To test this hypothesis, we exposed rats daily from post-natal days 1-21 to a non-home environment for 3 min. When the animals became adults, we studied the effects of glucocorticoid hormone corticosterone (CORT) on population spike (PS) amplitude and long-term potentiation of population spikes (PS-LTP) in vitro in the hippocampal CA1 region following activation of the Schaffer collateral fibers. Bath application of CORT reduced PS amplitude and subsequent induction of PS-LTP. This inhibitory effect of CORT was significantly greater in the slices from the novelty exposed rats (Novel) than the control rats that remained in their home cage (Home). Inhibition of population spike amplitude during CORT perfusion was 28.0+/-5.3% of baseline in Novel slices, and 9.1+/-4.4% in Home slices. CORT pre-exposure (20 min) also inhibited the subsequent induction of PS-LTP in Novel slices by 57.7+/-17.7% and by 7.5+/-12.1% in Home slices. These results provide electrophysiological evidence that neonatal novelty exposure results in functional increases in receptor sensitivity to CORT that enhances the inhibitory effects of CORT on field CA1 neuronal excitability and plasticity.

Interferon-gamma is crucial for surviving a Brucella abortus infection in both resistant C57BL/6 and susceptible BALB/c mice

Brucella abortus is an intracellular bacterial pathogen that causes chronic infections in humans and a number of agriculturally important species of animals. It has been shown that BALB/c mice are more susceptible to infections with virulent strains of Brucella abortus than C57BL/6 or C57BL/10 strains. In experiments described here, gene knock-out mice were utilized to elucidate some of the salient components of resistance. Resistant C57BL/6 mice with gene deletions or disruptions in the interferon-gamma (IFN-gamma), perforin or beta(2)-microglobulin genes had decreased abilities to control intracellular infections with B. abortus strain 2308 during the first week after infection. However, only the IFN-gamma knock-out mice had a sustained inability to control infections and this resulted in death of the mice at approximately 6 weeks post-infection. These mice had a continual increase in the number of bacterial colony-forming units (CFU) in their spleens until death. When BALB/c mice with the disrupted IFN-gamma gene were infected they had more splenic CFU at one week post-infection than control mice but the increase was not statistically significant and by 3 weeks they did not have more CFU than control mice. Moreover, the number of splenic bacteria did not increase in the BALB/c IFN-gamma knock-out mice between 6 and 10.5 weeks, although they died at 10.5 weeks, the time by which normal BALB/c mice were clearing the infection. Death in both strains of IFN-gamma gene disrupted mice coincided with symptoms of cachexia and macrophages comprised > or= 75% of the splenic leucocytes.

Mesoporous aluminosilicates with ordered hexagonal structure, strong acidity, and extraordinary hydrothermal stability at high temperatures

Highly ordered hexagonal mesoporous aluminosilicates (MAS-5) with uniform pore sizes have been successfully synthesized from assembly of preformed aluminosilcate precursors with cetyltrimethylammonium bromide (CTAB) surfactant. The aluminosilicate precursors were obtained by heating, at 100--140 degrees C for 2--10 h, aluminasilica gels at the Al(2)O(3)/SiO(2)/TEAOH/H(2)O molar ratios of 1.0/7.0--350/10.0--33.0/500--2000. Mesoporous MAS-5 shows extraordinary stability both in boiling water (over 300 h) and in steam (800 degrees C for 2 h). Temperature-programmed desorption of ammonia shows that the acidic strength of MAS-5 is much higher than that of MCM-41 and is comparable to that of microporous Beta zeolite. In catalytic cracking of 1,3,5-triisopropylbenzene and alkylation of isobutane with butene, MAS-5 exhibits greater catalytic activity and selectivity, as compared with MCM-41 and HZSM-5. The MAS-5 samples were characterized with infrared, UV--Raman, and NMR spectroscopy and numerous other techniques. The results suggest that MAS-5 consists of both mesopores and micropores and that the pore walls of MAS-5 contain primary and secondary structural building units, similar to those of microporous zeolites. Such unique structural features might be responsible for the observed strong acidity and high thermal stability of the mesoporous aluminosilicates with well-ordered hexagonal symmetry.

[A classification of anterior open bite]

OBJECTIVE

It intended to investigate different craniofacial types of anterior open bite.

METHODS

116 patients with anterior open bite were selected randomly. The craniofacial morphology and airway structures were measured and analyzed with multivariate analyses.

RESULTS

4 factors (mandible rotation factor, facial height factor, dental and skeletal saggittal factor and maxillary rotation factor) were extracted from 156 items including age, gender and craniofacial characteristics by data reduction and factor analysis procedure. Anterior open-bite patients were classified into 5 types, which are dental-alveolar type, mandibular clockwise rotation type, long face type, maxillary counter-clockwise rotation type and skeletal Class III type with K-means cluster analysis procedure. A simple cluster method was summarized to facilitate clinical practice.

CONCLUSION

It suggested that classification play an important role in diagnosis and decision making procedure.

[The clinic significance of serum hyaluronate and tumor necrosis factor alpha levels in liver diseases]

Serum levels of hyaluronic acid (HA) and tumor necrosis factor alpha (TNF alpha) in 94 patients with various liver diseases and 31 healthy controls were studied by RIA, Serum TNF alpha in hepatitis, liver cirrhosis (LC) and primary hepatic carcinoma (PHC) was higher than that of the control. Serum HA in chronic hepatitis, LC and PHC was higher than that in the control. The serum level of HA showed a positive correlation with the serum level of TNF alpha. It is considered that the increase of serum HA indicates an early fibrogenic tendency in patients with liver diseases. TNF alpha is involved in the formation of hepatic fibrosis.

Blockade of U50488H on sodium currents in acutely isolated mice hippocampal CA3 pyramidal neurons

The effect of opioid agonist U50488H on Na(+) currents was examined in freshly dissociated hippocampal neurons of mice using the whole-cell patch clamp technique. U50488H (1-100 microM) caused a concentration dependent reversible inhibition of the voltage-activated sodium currents. IC50 of 15.5 microM and Hill constant of 1.4 were calculated respectively. The inhibitory actions of U50488H on I(Na) were still observed in the presence of 30 microM naloxone. Moreover, under the action of U50488H, repetitive stimulation induced further inhibition which was frequency-dependent. The activation curve did not change before and after application of 10 microM U50488H. However, after exposure to 10 microM U50488H and repetitive depolarizing at 10 Hz, frequency-dependent inhibition occurred, and a mean shift of half-activation membrane potential by +20 mV could be induced. The inactivation curve was significantly changed toward negative membrane potential with 10 microM U50488H, and further negative shift was observed after repetitive depolarizing at 10 Hz. Our results indicate that U50488H could directly inhibit neuronal Na(+) currents without involvement in the activation of kappa-opioid receptors.

Effect of aluminum on long-term potentiation and its relation to L-arg-NO-pathway in hippocampal CA3 area of rats

Experiments were performed on 64 Sprague-Dawley rats under urethane anesthesia. Extracellular recording method was used to investigate the effect of aluminum(Al) microinjected into CA3 on long-term potentiation(LTP) in this area. The relationship between the inhibitory effect of Al and L-arginine-NO pathway was also studied. Microinjection of Al (0.5 mol/L, 1 microliter) into CA3 could block the induction of LTP in CA3. Microinjection of Al (0.5 mol/L, 1 microliter) into CA3 after LTP was induced could also decrease the amplitude of population spike (PS). The inhibitory effect of Al on LTP in CA3 could be enhanced by preinjection of NG-nitro-L-arginine (0.3 mol/L, 1 microliter). Preinjection of L-arginine (0.3 mol/L, 1 microliter) into CA3 could antagonize the inhibitory effect of Al on LTP. These results suggest that Al could block the induction of LTP and decrease the amplitude of PS potentiated in CA3. The effect of Al might be antagonized by L-arginine-NO pathway.

Picosecond optical bistability in metallophthalocyanine-doped polymer film waveguides

Ultrafast optical bistability was observed in a planar optical waveguide made with a 2,9,16,23-tetraoctadecanoylamido-substituted vanadyl phthalocyanine-doped polystyrene film. Input-output curves with hysteresis characteristics were measured with laser pulses of 60-ps pulse width at 532 nm. The switchup and switchdown times were less than 10 and 20 ps, respectively. The origin of the nonlinearity giving rise to optical bistability was predominantly electronic effects.

[Genetic epidemiology and a matched case-control study of bilateral breast cancer in Shanghai]

A matched case-control study on breast cancer was conducted in Shanghai from September 1990 to April 1992. Forty-six cases of bilateral breast cancer and 67 unilateral cases were studied. Results indicated that family history of breast cancer, personal history of benign breast diseases, high-level education, earlier menarche, and heavier body weight were the risk factors for breast cancer with conditional logistic regression analysis. Transmission of bilateral and unilateral breast cancer maybe conformed to Medellian recessive heredity model in simple segregation analysis, and all bilateral breast cancer, asynchronous bilateral breast cancer and asynchronous premenopausal bilateral breast cancer conformed to Medellian dominant heredity, and all unilateral breast cancer conformed to Medellian co-dominant heredity in complex segregation analysis.