Cytotoxicity of commercial and novel binary titanium alloys with and without a surface-reaction layer

Titanium-based alloys form a surface reaction layer when cast. This study investigated the effect of the surface reaction layer on the cytotoxicity of novel Ti-based binary alloys. The cytotoxicities of the novel alloys were compared with commercially pure titanium, Ti-6Al-4V and Ti-6Al-7Nb. Cast discs with or without the reaction layer were first tested for cytotoxicity, then for elemental release into cell-culture medium. The elements released into the extracts were measured by means of an inductively coupled plasma atomic emission spectrometer. The commercial and novel binary Ti-based alloys showed no statistically significant cytotoxicity, although some trends were noted for several alloys. The presence of the reaction layer did not significantly alter the cytotoxicity. These favourable biocompatibility results show that these novel alloys have promise for use in dental restorations.

SEM/EDS evaluation of porcelain adherence to gold-coated cast titanium

The adhesion between titanium and dental porcelain is related to the diffusion of oxygen to the reaction layer formed on cast-titanium surfaces during porcelain firing. The diffusion of oxygen could be suppressed by coating the titanium surface with a thin gold layer. This study characterized the effects of gold coating on titanium-ceramic adhesion. ASTM grade II CP titanium was cast into a MgO-based investment (Selevest CB, Selec). The specimen surfaces were air abraded with 110-microm Al(2)O(3) particles. Gold coating was applied on titanium surfaces by three methods: gold-paste (Deck Gold NF, Degussa-Ney) coating and firing at 800 degrees C for three times, single gold-paste coating and firing followed by sputter coating (40 mA, 500 s), and sputter coating (40 mA, 1000 s). Surfaces only air abraded with Al(2)O(3) particles were used as controls. An ultra-low-fusing dental porcelain (Vita Titankeramik, Vident) was fused on titanium surfaces. Specimen surfaces were characterized by SEM/EDS and XRD. The titanium-ceramic adhesion was evaluated by a biaxial flexure test (N = 8), and area fraction of adherent porcelain (AFAP) was determined by EDS. Numerical results were statistically analyzed by one-way ANOVA and the Student-Newman-Keuls test at alpha = 0.05. SEM fractography showed a substantial amount of porcelains remaining on the gold-sputter-coated titanium surfaces. A new Au(2)Ti phase was found on gold-coated titanium surface after the firing. Significantly higher (p <.05) AFAP values were determined for the gold-sputter-coated specimens compared to the others. No significant differences were found among the other groups and the control. Results suggested that gold coatings used in this study are not effective barriers to completely protect titanium from oxidation during the porcelain firing, and porcelain adherence to cast titanium can be improved by gold-sputter coating used in the present study.

Leaching from solid waste incineration ashes used in cement-treated base layers for pavements

Waste incineration bottom ash and treated flue gas cleaning products mixed with 2.5% of cement (50 kg/m3) were tested in the laboratory in terms of compressive strength and tank leaching tests over a 64-day period. Although the material displayed lower mechanical strength than a reference concrete, the strength still was sufficient for use as a base layer for roads. The metal content in the incineration-residue-based specimens was up to 100 times higher than in the reference concrete, suggesting that the mixed waste incineration residue should be used only for dedicated purposes. The leaching of Cl and Na was increased by a factor of 20-100 from the incineration-residue-based specimens as compared to the reference, while the leaching of K, Ca and SO4 was increased by a factor of 2-10. The leaching of heavy metals was also higher from the incineration-residue-based specimens than from the reference with respect to Cu (50 times), Cd, Pb and Zn (5 times), but not with respect to Cr and Ni. The leaching curves did only allow for a closer evaluation of the leaching process in a few cases. The physical retention of the constituents seemed to be the same in the reference as in the incineration-residue-based specimens. Heavy metal leaching was limited by enhanced chemical retention in the incineration-residue-specimens as compared to the reference. Since no quality criteria in terms of leaching from a monolithic material are currently available, the leaching issue must be evaluated case by case.

Corrosion behavior of cast titanium with reduced surface reaction layer made by a face-coating method

This study characterized the corrosion behavior of cast CP titanium made with a face-coating method. Wax patterns were coated with oxide slurry of Y(2)O(3) or ZrO(2) before investing with a MgO-based investment. Three surface preparations were tested: ground, sandblasted, and as-cast. Uncoated castings served as controls. Sixteen-hour open circuit potential (OCP) measurement, linear polarization and potentiodynamic cathodic polarization were performed in an aerated modified Tani-Zucchi synthetic saliva at 37 degrees C. Anodic polarization was conducted in the same deaerated medium. Polarization resistance (R(p)) and Tafel slopes were determined. Corrosion current density was calculated for each specimen. Results (n=4) were subjected to nonparametric statistical analysis (alpha=0.05). Cross sections of cast specimens were examined by optical microscopy. Energy dispersive spectroscopy (EDS) spot analysis was performed at various depths below the surface. The OCP stabilized within several hours for all the specimens. Apparent differences in anodic polarization behavior were observed among the different surfaces. A distinctive wide passive region followed by breakdown was seen on specimens with ground and sandblasted surfaces. There were no significant differences in the corrosion resistance among the control and the two face-coating groups for each group. The Mann-Whitney test showed significantly lower OCP and higher R(p) values for ground surfaces. The surface condition significantly affected the corrosion behavior more than the face coating methods. In most cases, specimens with as-cast surfaces exhibited the least corrosion resistance during the potentiodynamic anodic polarization.

Vascular endothelial growth factor (VEGF) expression and the effect of exogenous VEGF on survival of a random flap in the rat

The induction of endogenous vascular endothelial growth factor (VEGF) production in the skin flap with ischemic injury and the effect of exogenous VEGF on survival of the ischemic skin flap were studied in rats. A dorsal flap model (3x10 cm(2)) was used in this study. In Part I, biopsies were taken from the flap at 2.5, 5.5, and 8.5 cm distances from the distal edge at 0, 6, 12, and 24 h after the flaps were sutured. Malonyldialdehyde (MDA) and VEGF(165) protein level were measured. In Part II, exogenous VEGF (1 microg/ml) was injected subdermally into the flaps in 14 rats before the flaps were replaced. Flaps that received a saline injection were used as the controls. The skin paddle survival was measured on postoperative day five. The results showed that the MDA level in the distal part of the flap significantly increased at 24 h postoperatively when compared to MDA in other parts of the flap. However, VEGF levels in the distal part of the flap significantly decreased when compared to the middle part of the flap. Subdermal injection of exogenous VEGF to the distal area of the flap could significantly improve survival of the distal flap (89% of total skin paddle) when compared to the control, which had a 64% mean percent survival. We conclude that production of endogenous VEGF protein is significantly increased in the skin flap with mild ischemia, but decreased in the flap with severe ischemia. Administration of exogenous VEGF could significantly enhance survival of ischemic flaps.

Measurement of the spatial coherence function of undulator radiation using a phase mask

A measurement of the horizontal coherence function of 7.9 keV radiation from an undulator beam line at the Advanced Photon Source is reported. X-ray diffraction from a phase-shifting mask was used, and the coherence function was measured as a function of the width of beam-conditioning slits in the beam line. The coherence distribution is found to be best described by a Lorentzian function.

The complete nucleotide sequence of Beet black scorch virus (BBSV), a new member of the genus Necrovirus

The complete nucleotide sequence of Beet black scorch virus (BBSV) was determined. The BBSV genome is composed of 3641 nucleotides and has similar organization with Tobacco necrosis virus D of 61% nucleotide identity. The 5'-proximal open reading frame (ORF) encodes a putative 23 kDa protein and a 82 kDa protein by reading-through of an amber termination codon. Three small ORFs located in the center of the genome may encode for a 4.2 kDa protein and two 7 kDa proteins. The 3'-proximal ORF encodes a 24.5 kDa protein equivalent in mass to the viral coat protein. Considering biological and molecular similarities with TNV, it is concluded that BBSV is a new member of the genus Necrovirus.

Realities of high-throughput liquid chromatography/mass spectrometry purification of large combinatorial libraries: a report on overall sample throughput using parallel purification

We report on the development of a validated, streamlined high-throughput process for the purification of parallel-synthesis-derived combinatorial libraries. The steps involved in this library purification process include dissolution of dry films of crude synthetic material, dual-column LC/MS purification, dual-column postpurification analysis, quantitation, reformatting, and submission of pure compounds for registration. Although the purification and postpurification analysis times decreased essentially linearly as a function of the number of HPLC columns employed, it was not possible to decrease the total purification process time linearly as a function of the number of columns employed in the system. This was due primarily to the fact that numerous steps in the total purification process are independent of sample analysis and purification (e.g., evaporation, reconstitution, and reformatting, etc.). Additionally, experiments were also performed to assess whether separate gradient pumps were necessary for each channel of this two-channel LC/MS or if acceptable results could be reliably obtained by splitting the flow from one set of gradient pumps between two HPLC columns. On the basis of the parallel, two-column LC/MS system employed in this work, throughput estimates were extrapolated to more massively parallel systems (e.g., four-channel LC/MS).

Observation of columnar microstructure in step-graded Si1-xGex/Si films using high-resolution X-ray microdiffraction

Columnar microstructure in step-graded Si(1-x)Ge(x)/Si(001) structures with low threading dislocation densities has been determined using high angular resolution (approximately 0.005 degrees ) x-ray microdiffraction. X-ray rocking curves of a 3-microm-thick strain-relaxed Si(0.83)Ge(0.17) film show many sharp peaks and can be simulated with a model having a set of Gaussians having narrow angular widths (0.013 degrees -0.02 degrees ) and local ranges of tilt angles varying from 0.05 degrees to 0.2 degrees. These peaks correspond to individual tilted rectangular columnar micrograins having similar (001) lattice spacings and average areas of 0.8 to 2.0 microm(2).

Accuracy of sampling methods in morphometric studies of human sural nerves

The aim of this study was to ascertain the minimum sample required to accurately measure the total number of myelinated fibres, mean myelinated fibre density (MFD), myelinated fibre diameter (Ds) and axonal diameter (Da) in morphometric studies of sural nerve biopsies. Measurements were obtained by sampling a single fascicle or systematic sampling of up to 50% of the total transverse fascicular area of two control and eighteen pathological sural nerves showing varying degrees of demyelination and axonal degeneration. MFD and fibre size were heterogeneous between fascicles in both control and pathological sural nerves, and morphometric results from one fascicle and systematic sampling of up to 50% of the total transverse fascicular area did not accurately represent the whole myelinated fibre population in the sural nerve. For accurate morphometric data it is necessary to quantitate all the myelinated fibres in the sural nerve.

X-ray microdiffraction images of antiferromagnetic domain evolution in chromium

Magnetic x-ray diffraction combined with x-ray focusing optics was used to image individual antiferromagnetic spin density wave domains in a chromium single crystal at the micron scale. The cross section for nonresonant magnetic x-ray scattering depends on the antiferromagnetic modulation vector and spin polarization direction and allows these quantities to be extracted independently. The technique was used to show that the broadening of the nominally first-order "spin-flip" transition at 123 kelvin, at which the spins rotate by 90 degrees C, originates at the walls between domains with orthogonal modulation vectors. During cooling, the transition begins at these walls and progresses inward. The modulation vector domains are themselves unchanged.

[A comparative morphometrical study on development of anterior septonasal accessory organs in the cleft palate mice]

OBJECTIVE

The aim of this study was to investigate whether cleft palate is associated with the mal-development of the vomer, Jacobson's organ and para-septal cartilage.

METHODS

Sixty craniomaxillary complexes, which came from 30 pairs of trisomy 18 with cleft palate (Ts + CP) and euploid mouse fetuses were precisely orientated in the coronal plane, and serially sectioned at 7 microns thickness. With the aid of computer imaging analysis system the vomer in coronal and sagittal direction, Jacobson's organ and para-septal cartilage in the boundary plane of the primary and secondary palate were measured and compared quantitatively.

RESULTS

The hard tissues (including the vomer and para-septal cartilage) of the anterior nasal septum in Ts + CP foetuses show serious developmental hypoplasia, however, the Jacobson's organ had no significant different between the cleft and non-cleft samples.

CONCLUSION

Development hypoplasia of these hard tissues may be more closely related with the autosomal trisomic condition more than the cleft palate.

[Applied study on computerized quantitative facial nerve functional estimating system]

OBJECTIVE

To prove the clinical applied value of quantitative facial nerve functional estimating system (QFES) by comparing the estimating results of the computerized QFES with manual QFES.

METHODS

50 volunteers with normal facial nerve function were used. Every volunteer was taken 7 photos with digital camera, which including static, and forehead wrinkle, eyebrows knit tight, eyes closed tight, nose wrinkle, smile, pout and mouth open to maximal seven expressions. The facial nerve function was estimated by computerized QFES, and the estimating results were compared with manual estimations by QFES in our study during 1991-1994.

RESULTS

All estimating indices in this study were in the range of 0.70-0.90 as well as the manual estimating results. However, the stand deviation in this study showed significantly smaller than the previous study.

CONCLUSIONS

QFES is an ideal quantitative facial nerve functional estimating system, after computerization the efficiency is increased and the systemic error is decreased. It will benefit to apply computerized QFES in the facial nerve function estimating fields.

Overexpression of Ogt reduces MNU and ENU induced transition, but not transversion, mutations in E. coli

Studies of alkylation-induced mutations in Escherichia coli FX-11 revealed that both N-ethyl-N-nitrosourea (ENU) and N-methyl-N-nitrosourea (MNU) produced tRNA suppressor mutations (G:C to A:T) but only ENU produced a significant number of backmutations (A:T to G:C, A:T to T:A and A:T to C:G). Further, the ENU-induced transversions were absent in a UmuC-defective strain. This suggested that transition mutations could result from alkylation of guanine or thymine at the O(6)- and O(4)-positions, respectively, but that transversions might result from alkylation of thymine at the O(2)-position. To test this idea, the gene encoding O(6)-alkylguanine-DNA methyltransferase (ogt) was recombined into a plasmid to overexpress the cellular levels of this enzyme. Ogt protein can de-alkylate O(6)-alkylguanine and O(4)-alkylthymine, but not O(2)-alkylthymine. Cells harboring the plasmid (or a control plasmid lacking the ogt gene) were exposed to different concentrations of MNU or ENU and the resulting mutations were analyzed. With either MNU or ENU, the frequency of GlnV(o) suppressors was reduced about 70-fold in the Ogt-overexpressing cells, suggesting that Ogt eliminated O(6)-alkylguanine. Similarly, GlnU(o) suppressor frequencies were substantially reduced. In contrast, the reduction in frequency for the backmutations was slight, only about 2.5-fold with MNU and less than two-fold for ENU. However, DNA sequence analysis of the backmutations showed that only A:T to G:C transitions were affected by overexpression of Ogt, suggesting repair of O(4)-alkylthymine. The frequency of transversions, in comparison, was essentially unaltered. These results implicate O(2)-alkylthymine as a likely candidate for transversion mutagenesis induced by ENU.

Phase sensitive x-ray diffraction imaging of defects in biological macromolecular crystals

Conventional x-ray diffraction topography is currently used to map defects in the bulk of protein crystals, but the lack of sufficient contrast is frequently a limiting factor. We experimentally demonstrate that this barrier can be circumvented using a method that combines phase sensitive and diffraction imaging principles. Details of defects revealed in tetragonal lysozyme and cubic ferritin crystals are presented and discussed. The approach enabling the detection of the phase changes of diffracted x rays should prove to be useful in the study of defect structures in a broad range of biological macromolecular crystals.

Analysis of genes differentially expressed in astrocytes stimulated with lipopolysaccharide using cDNA arrays

We used cDNA arrays to investigate differentially expressed genes in astrocytes challenged with lipopolysaccharide (LPS). Astrocyte cultures were prepared from 1-day-old rat brains. Purified astrocytes were treated with LPS (1 microg/ml) for 2, 8 and 48 h. Differentially expressed genes in these astrocytes were examined with Atlas rat cDNA arrays. At all the three time points studied, three genes were found consistently up-regulated: I-kappaB alpha chain, NF-kappaB, and interferon induced protein. In addition to these three, six other genes were also up-regulated at 2 and 8 h. They were genes encoding vascular cell adhesion protein 1 (VCAM-1), interferon regulatory factor 1 (IRF-1), mitochondrial hydroxymethylglutaryl-CoA synthase (HMG-CoA synthase), aldehyde dehydrogenase 2, macrophage inflammatory protein 1 (MIP-1) and neurotensin receptor 2. At these two time points, three genes were down-regulated: copper-zinc-containing superoxide dismutase 1 (SOD-1), insulin-like growth factor binding protein 1 (IGFBP-1), and insulin-like growth factor binding protein 3 (IGFBP-3). Expression of several differentially expressed genes in cDNA array (I-kappaB, VCAM-1 and MIP-3) were further confirmed by reverse transcription polymerase chain reaction study. The prominently modulated genes could be classified into three categories: nuclear transcription factors, pro-inflammatory cytokines/chemokines and metabolic enzymes. Application of pyrrolidine dithiocarbamate, an inhibitor of nuclear factor-kB (NF-kappaB), prior to LPS stimulation not only prevented up-regulation of NF-kappaB gene expression, but also completely blocked up-regulation of pro-inflammatory cytokine genes (TNF-alpha and interleukin-1beta) and two chemokine genes: CXC chemokine LIX and CC chemokine MIP-3 alpha. These results indicate that both up-regulation of inflammatory cytokine expression and down-regulation of growth factor expression are probably involved in the response of astrocytes upon exposure to LPS.

A quantitative histochemistry technique for measuring regional distribution of acetylcholinesterase in the brain using digital scanning densitometry

Studies of brain acetylcholinesterase (AChE) are traditionally based on biochemical assays, immunoreactivity, and histochemistry. Conventional histochemistry yields rich morphological data from tissue sections but yields quantitative results only with great difficulty. Several histochemical methods developed in recent years, including microdensitometry, microphotometry, and video-based histochemistry, are effective in quantitative and detailed study of AChE in tissue sections. However, they are usually time-consuming. As we report here, we adapted digital scanning densitometry to quantitate AChE histochemical staining in brain sections. The AChE and butyrylcholinesterase (BuChE), as measured by the method, were heterogeneously distributed throughout the brain, results that are consistent with those obtained by biochemical methods. The staining intensity is dependent on section thickness, substrate concentration, and reaction time. The cholinesterase inhibitor methyl paraoxon significantly decreased AChE staining intensity. Furthermore, data acquired from densitometry are similar to those obtained by video-based microscopy or by spectrophotometry. The advantage of the densitometric measurements compared to other quantitative histochemical methods is that it is very rapid while collecting data that are equivalent in quality. Because the digital scanning densitometers provide high quality and sensitive imaging, wide dynamic ranges, and convenient image analysis software, they are very useful tools in quantitative histochemistry.

Effect of heat treatment on mechanical properties of age-hardenable gold alloy at intraoral temperature

OBJECTIVE

The aim of this study was to investigate the effect of various heat treatments on the mechanical properties of gold alloys capable of age-hardening at intraoral temperature.

METHODS

Dumbbell-shaped patterns (ISO 6871) were cast with three gold alloys (Sofard; NC Type-IV; Aurum Cast, NihombashiTokuriki Co.). The Sofard alloy is age-hardenable at intraoral temperature. The castings underwent various heat treatments [as-cast (AC); solution treatment (ST); high-temperature aging (HA); intraoral aging (IA)]. After these heat treatments, ultimate tensile strength (UTS), 0.2% offset yield strength (YS), and elongation (EL) were measured at a strain rate of 1.7x10(-4)/s. Fracture surfaces of the specimens after tensile testing were observed using SEM. Vickers hardness was also measured after heat treating.

RESULTS

After IA, the hardness values of the Sofard alloy increased and reached values similar to the hardness of the Sofard specimens aged at high temperature (HA). The hardness values of the NC Type-IV and Aurum Cast specimens slightly increased after IA, but did not reach the values of the specimens after HA. All the Sofard, NC Type-IV and Aurum Cast specimens showed significantly (P<0.05) greater hardness values after HA, compared with the values after any other heat treatments (AC, ST and IA). The UTS and YS of the specimens indicated a tendency similar to the results obtained for hardness. The Sofard specimens with ST showed the greatest elongation compared to the corresponding NC Type-IV and Aurum Cast specimens. However, the elongation of the Sofard specimens was abruptly reduced after intraoral aging.

CONCLUSION

Intraoral aging significantly improved the mechanical properties and hardness of the Sofard alloy.

National survey on prevalence of cancer pain

OBJECTIVE

To collect nationwide basic data about cancer related pain.

METHODS

Sixty cancer patients in each province were randomly selected to participate in this survey. The subjects represented all stages of cancer, tumor sites, and different demographic characteristics. Two self-designed structured questionnaires including reasons, types of pain and pain management were used by patients and physicians respectively. Subjects were asked to report whether he/she had experienced any type of cancer related pain and filled out the equivalent questionnaire. The severity of pain was assessed by using "visual analogue scale". Original data input and analysis were using EPI-INFO software package.

RESULTS

The result showed that 61.6% (958/1555) of patients had different types of cancer related pain. Majority of pain (85.1%) were caused by advanced cancer. The major reasons (64.4%) for poor management or impedimental factors of pain care are due to patient including over-concern on opioid analgesic addiction, reluctance to report pain or refused to use opioid analgesic until at times when pain is intolerable; 26.8% belonged to physician's reasons including fear to cause addiction on opioid and lack of knowledge about cancer pain management; 16.2% are due to lack of different kinds of opioid analgesic for use and 16.1% belonged to drug regulation.

CONCLUSIONS

The results showed that majority of patients (61.6%) had different types of cancer related pain. In most of patients, cancer pain was relieved when they were treated. The major reason for under-treatment or impeded factors for effective relief of cancer pain was fear of opioid addiction by both medical professionals and patients.

[Schizophrenia and dopamine D4 gene polymorphism in Chinese population: association analysis]

OBJECTIVE

To investigate the association of the 48 bp variable number tandem repeat (VNTR) polymorphism in the dopamine D4 receptor (DRD4) gene exon III with schizophrenia in Chinese Han population.

METHODS

Case-control association study was adopted to analyze the association between the 48 bp VNTR polymorphism of DRD4 gene exon III in 510 DSM-IV schizophrenics and 171 psychiatrically normal controls.

RESULTS

(1) The DRD4 gene 48 bp VNTR polymorphism was manifested as 2-7 repeats, with the 4 repeats the most common (78.6% in schizophrenics and 76.9% in controls respectively). The frequency of 2 repeats was 16.2% and 19.3% in the schizophrenics and controls respectively. (2) The genotypic frequency was statistically significantly different between the schizophrenics and the controls. The genotypic frequency of short tandem repeats (2/2 and 2/3 genotype) was lower in patients (3.3%) than in controls (10.5%) (chi 2 = 14.88, df = 2, P = 0.00). (3) the frequency of the genotype with 4-repeat allele in patients was higher (95.9%) than in controls (88.3%) (chi 2 = 13.00, df = 1, P = 0.000).

CONCLUSION

The most common allele in Chinese schizophrenics was 4 repeats in the 48 bp VNTR polymorphism of DRD4 gene exon III. The repeat number of 48 bp is probably associated with schizophrenia. Lack of 2-3 repeats or excess of genotype with 4-repeat allele may be associated with increased vulnerability to schizophrenia.

[Aminopeptidase inhibitor Bestatin induces HL-60 cell apoptosis through activating caspase 3]

OBJECTIVE

To study the variation and significance of caspase 3 activity in the process of amino-peptidase inhibitor--bestatin (BS) inducing human leukemic cell apoptosis.

METHODS

Cell apoptosis was evaluated by light microscopy, TUNEL labeling and flow cytometry (FCM). Caspase 3 activity was detected by colorimetry. The mitochondrial transmembrane potentials (DeltaPsi(m)) were detected by Rhodamine123 staining.

RESULTS

The apoptotic morphology, apoptotic peak on FCM and positive Annexin V(FITC) on cell membrane showed that BS could induce HL-60 cell apoptosis in a dose- and time-dependent manner. Caspase 3 activity was significantly higher in the apoptotic cells than in control cells. The apoptosis induced by BS was inhibited by AC-DEVD-CHO. The DeltaPsi(m) of cells treated with BS declined.

CONCLUSION

BS induces apoptosis of human acute leukemic cells through activation of caspase 3.

Focal myelin swellings and tomacula in anti-MAG IgM paraproteinaemic neuropathy: novel teased nerve fiber studies

Focal myelin swellings and tomacula in teased nerve fibers from a case of IgM anti-myelin-associated glycoprotein (MAG) paraproteinaemic neuropathy were examined using a novel technique. Five different morphologic abnormalities were identified--myelin sheath outfolding, myelin sheath infolding, enlargement of the adaxonal space, myelin degeneration, multiple increased concentric loops--and a combination of these structural abnormalities often occur in association with myelin degeneration. Similar structural changes were found in externally normal segments of teased fibers without evidence of myelin swelling or tomacula from the same case. These structural abnormalities are consistent with a disturbance of the normal adhesion functions of MAG in the maintenance of axon-myelin relationships.

In vitro susceptibility to TRAIL-induced apoptosis of acute leukemia cells in the context of TRAIL receptor gene expression and constitutive NF-kappa B activity

The TNF-related apoptosis-inducing ligand (TRAIL) is currently under evaluation as a possible (co-)therapeutic in cancer treatment. We therefore examined 129 cell samples from patients with de novo acute leukemia as to their constitutive susceptibility to TRAIL-induced apoptosis In vitro. Only 21 (16%) cell samples revealed at least 10% TRAIL-susceptible cells/sample as detected by flow cytometric annexinV staining after 24 h culture compared with medium control. Precursor B cell ALL samples (11 (27%) of 41) were more TRAIL-susceptible compared with AML (5 (9%) of 54; P < 0.05) but not compared with precursor T cell ALL (5 (15%) of 34; P = 0.20). Furthermore, we examined constitutive mRNA expression levels of TRAIL receptors R1-R4 by semi-quantitative RT-PCR (n = 58). Expression levels were heterogeneous, however, there was no significant correlation between the expression of the signal-transducing receptors (R1, R2) as well as of the decoy receptors (R3, R4) and TRAIL sensitivity in this series. Constitutive NF-kappa B activity has been shown to influence TRAIL susceptibility of leukemic cells. In 39 leukemic cell samples examined, we found a generally high NF-kappa B activity as detected by electrophoretic mobility shift assay which did not differ between TRAIL-susceptible and TRAIL-resistant cases. Finally, 49 acute leukemic cell samples were coincubated with doxorubicin in vitro. Doxorubicin sensitized four of 35 initially TRAIL-resistant samples and augmented TRAIL-induced apoptosis in two of 14 TRAIL-susceptible samples. In summary, constitutive TRAIL susceptibility differs between leukemia subtypes and does not correlate with mRNA expression levels of the TRAIL receptors R1-R4 as well as constitutive NF-kappa B activation status. The observed sensitization of leukemic cells to TRAIL by doxorubicin in vitro indicates that TRAIL should be further evaluated as to its possible role as an in vivo cotherapeutic in acute leukemia.

Apoptotic response to homoharringtonine in human wt p53 leukemic cells is independent of reactive oxygen species generation and implicates Bax translocation, mitochondrial cytochrome c release and caspase activation

In the present study, we investigated the in vitro apoptotic response of leukemic cells to the cellular stress induced by homoharringtonine (HHT), a plant alkaloid with antileukemic activity which is currently being tested for treatment of acute and chronic leukemias. A comparison of leukemic cell lines with different p53 gene status revealed a considerably higher sensitivity to HHT-induced apoptosis in the cells with a wt p53, and apoptotic events in wt p53 leukemia cells (MOLT-3 cell line) were studied in more detail. To this end, we examined components of apoptotic cascades including Bax expression and its intracellular localization, changes of mitochondrial membrane potential (MMP), reactive oxygen species (ROS) levels, cytochrome c release from mitochondria and activation of caspases. Bax protein levels did not increase despite an up-regulation of bax at mRNA level. However, Bax translocation from cytosol towards mitochondria was observed. In addition, we observed a release of cytochrome c from the mitochondria, and the localization changes of both Bax and cytochrome c were found already at the early, annexin V-negative stage of HHT-induced apoptosis. HHT-treated MOLT-3 cells revealed loss of MMP as well as activation of caspases demonstrated by DEVD-, IETD- and LEHD-tetrapeptide cleavage activity in the cell lysates. ROS levels only slightly increased in HHT-treated cells and antioxidants did not prevent apoptosis and MMP changes. Therefore, wt p53 leukemic cells respond to HHT-specific cellular stress by induction of ROS-independent apoptotic pathway characterized by translocation of Bax, mitochondrial cytochrome c release and activation of caspases.

Porcelain adherence to dental cast CP titanium: effects of surface modifications

OBJECTIVES

A reaction layer forms on cast titanium surfaces due to the reaction of the molten titanium with the investment material. Such a layer prevents strong adhesion between titanium and porcelain. This study characterized the effects of surface modifications on cast titanium surfaces and titanium-ceramic adhesion.

METHODS

ASTM grade II CP titanium was cast into an MgO-based mold. Castings were devested by sandblasting with alumina particles, and subjected to surface modification by immersion in one of the following solutions: (1) 35% HNO3-5% HF at room temperature for 1min; (2) 50% NaOH-10% CuSO4 x 5H2O at 105 degreesC for 10min; (3) the NaOH-CuSO4 solution followed by the HNO3-HF solution; (4) 50% NaOH-10% NaSO4 at 105 degreesC for 10 min; (5) the NaOH-NaSO4 solution followed by the HNO3-HF solution; and (6) 50% NaOH solution at 105 degreesC for 10min. Surfaces only sandblasted with alumina were used as controls. Specimen surfaces were characterized by XRD and SEM/EDS, and hardness-depth profiles were determined. All specimens were sandblasted with 110 microm alumina particles before porcelain firing. An ultra-low-fusing porcelain (Vita Titankeramik) was fused on the titanium surfaces. The titanium-ceramic adhesion was characterized by a biaxial flexure test, and area fraction of adherent porcelain (AFAP) was determined by X-ray spectroscopy.

RESULTS

EDS analyses revealed a substantial amount (13-17 wt%) of Al on the control, and specimens modified with Methods 2, 4, and 6. XRD revealed residual stress in the titanium surfaces and corundum on the control, and Methods 2, 4, and 6 specimens. A new Ti(Cu, Al)2 phase was identified on the titanium surfaces modified by immersion in 50% NaOH-10% CuSO4 x 5H2O aqueous solution. Reduced residual stress was observed on Method 1, 3, and 5 specimens. No corundum peaks were detected on these specimens. Compared to the control, significantly lower (P < 0.05) hardness values were found for Methods 1-3 and Method 5 specimens at 20 microm below the surfaces and for Method 1-5 specimens at 50 microm below the surfaces. Significantly higher (P < 0.05) AFAP values were found for surfaces modified with Methods 2-6 compared to the control and Method 1, and no significant differences were found among Methods 1-6, and between control and Method 1.

SIGNIFICANCE

Based on the results from the present study, porcelain adherence to cast CP titanium can be improved by the caustic baths used in the study.

[Involvement of mitochondrial membrane potential in the homoharringtonine induced apoptosis of leukemic T-cells]

OBJECTIVE

Investigation of the role of mitochondrial membrane potential (MMP) in the homoharringtonine (HHT)-induced apoptosis.

METHODS

Annexin V staining, flow cytometry and confocal laser scan microscopy were used to observe the relationship between Bax, cytochrome C and MMP in the HHT-induced apoptosis of leukemic T lymphocytic line Molt-3.

RESULTS

The induction of apoptosis by HHT resulted in the translocation of Bax from cytosol to mitochondrial membrane and the decrease of cellular MMP, followed by the release of cytochrome C from mitochondria to cytosol.

CONCLUSIONS

Changes of mitochondrial membrane potential might play a critical role in the HHT-induced apoptosis of leukemic T-cells.

Intrauterine hypoxia-ischemia alters expression of the NMDA receptor in the young rat brain

Effects of intrauterine hypoxia-ischemia (HI) on expression of the NMDA receptor subunits as well as on [3H]MK-801 binding of the NMDA receptor were studied in 1-day to 30-day old rat brain. Intrauterine HI conditions were achieved on gestation day 17 by clamping the uterine vasculature for 30 min followed by removal of the clamps to permit reperfusion. As determined by reverse-transcriptase polymerase chain reaction, prenatal HI significantly reduced mRNA expression of the NRI subunit of the NMDA receptor in the hippocampus of 4, 8, and 30-day old rat brains. NR2A and NR2B subunit mRNAs were expressed in the hippocampus and the cortex of both the control and the prenatal HI rat brains. Intrauterine HI did not significantly affect expression of either the NR2A or NR2B subunit mRNA. Consistent with the RT-PCR data, protein expression of the NRI subunit in the hippocampus, but not the cortex, of 21-day old prenatal HI rat brains was significantly decreased as compared to the control rat brain. Intrauterine HI also significantly reduced binding affinity, but not the number of binding sites, of the NMDA receptor to [3H]MK-801, a noncompetitive antagonist of the NMDA receptor, in the hippocampus of 21-day old rat brain. The overall results suggest that prenatal HI-induced reduction of NRI expression and the altered binding ability of the NMDA receptor in the young rat brain may contribute to other long-lasting effects of intrauterine HI that we reported previously.

Simultaneous determination of Ziagen and its phosphorylated metabolites by ion-pairing high-performance liquid chromatography-tandem mass spectrometry

An ion-paring HPLC-MS-MS method with positive ion mode electrospray ionization has been developed to simultaneously quantify Ziagen, carbovir monophosphate, carbovir diphosphate and carbovir triphosphate. N',N'-Dimethylhexylamine was used as the ion-pairing agent. The presence of this ion-pairing agent allowed the retention and separation of the four compounds on a reversed-phase HPLC column as well as the detection of the nucleotides with positive ion mode electrospray ionization. The limits of detection were found to be better than 25 nM for all the analytes. Calibration curves of the analytes showed excellent linearity over the range of 25 nM to 5 microM. The relative standard deviations and accuracies for replicate analyses of quality control samples were less than 15%. The method has been successfully applied to the analysis of these compounds in human liver cells treated with Ziagen.

Chronic ischemia preferentially causes white matter injury in the neonatal rat brain

Chronic ischemic brain injuries were studied in 7- and 14-day-old rat pups, which were subjected to bilateral carotid artery occlusion (BCAO) on postnatal day 1. BCAO preferentially injured white matter in the corpus callosum, subcortex and internal capsule areas while largely spared cortical neurons. White matter rarefaction in the corpus callosum was observed in 12 out of the 17 BCAO rat brains and significantly enlarged lateral ventricles were found in five out of seven P14 BCAO rat brains. These white matter changes were similar to injuries found in newborn infants with periventricular leukomalacia (PVL). White matter injuries in the 7-day-old BCAO rat brain were accompanied with increased activation of microglia/macrophages, as indicated by ED1 and OX42 positive immunostaining. Immature oligodendrocytes in the 7-day-old BCAO rat brain, as indicated by O4+/O1+ staining, were much fewer than in the sham-operated rat brain. Immunostaining for myelin basic protein (MBP) at the fimbria hippocampus and the internal capsule areas in the 7-day-old BACO rat brain was also much less than in the control rat brain. Consistent with the immunostaining data, MBP mRNA expression in the 7-day-old, but not in the 14-day-old, BCAO rat brain was significantly less than in the control rat brain. The overall results suggest that pre-oligodendrocytes and immature oligodendrocytes might be major targets for chronic ischemic insults and activated microglia/macrophages are possibly involved in the process of white matter injury.

Optimization of conditions for bacteriocin extraction in PEG/salt aqueous two-phase systems using statistical experimental designs

The bacteriocin nisin was extracted in PEG/salt aqueous two-phase systems (ATPS) using the property that the systems can extract hydrophobic proteins. The concentrations of the phase-forming components, PEG 4000 and Na(2)SO(4), were optimized for nisin recovery by means of statistical experimental designs, and it was found that they strongly influenced nisin recovery. The optimal composition of ATPS was found to be 15.99% (w/w) PEG 4000 and 15.85% (w/w) Na(2)SO(4) (pH 2), and the optimal ATPS allowed an 11.60% increase of nisin recovery compared to the standard method of nisin assay.

X-ray diffraction characterization of dental gold alloy-ceramic interfaces

X-ray diffraction (XRD) was employed to study dental alloy-ceramic interfaces. A Au-Pd-In alloy, which requires oxidation before porcelain firing, and a Au-Pt-Pd-In alloy, which does not require oxidation before porcelain firing, were selected in this study. Alloy specimens were centrifugally cast. Specimen surfaces were metallographically polished through 0.05 microm Al2O3 slurries. A thin layer (< 50 microm) of a dental opaque porcelain was fired on the alloy surfaces with and without initial oxidation. XRD was conducted at room temperature on four types of alloy specimens: polished, oxidized, porcelain fired after alloy oxidation, and porcelain fired without initial alloy oxidation. XRD was also performed on fired opaque porcelain without an alloy substrate. The detection of prominent gold solid solution peaks from alloy-ceramic specimens indicated that the incident X-ray beam reached the alloy-ceramic interface. In2O3 and beta-Ga2O3 were identified on the oxidized Au-Pd-In alloy, while In2O3 and SnO2 were detected on the oxidized Au-Pt-Pd-In alloy. Preferred orientation was observed for all the oxides formed on the alloys. Minimum lattice parameter changes (<1%) for the gold solid solutions were observed for both alloys before and after oxidation and porcelain firing. Leucite (KAlSi2O6, TiO2, ZrO2 and SnO2 were detected on the fired opaque porcelain. For both alloys, no additional oxides were identified at the metal-ceramic interfaces beyond those present in the oxidized alloys and the opaque porcelain. Similar results were obtained from alloy-ceramic interfaces where there was no prior alloy oxidation. The results indicate the critical role of alloy surface oxides in metal-ceramic bonding and support the chemical bonding mechanism for porcelain adherence.

[Sequences of 5S-rRNA gene spacer region and comparison of alkaloid content in Fritillaria thunbergii from different habitats]

OBJECTIVE

To study the genetic basis of the formation of indigenous Chinese medicine materials.

METHODS

The 5S-rRNA gene spacer regions in F. thunbergii from different habitats were amplified with AS and AS-1 as primers, and then sequenced. Total alkaloid contents were assayed by acid dye colorimetry, and 2 main alkaloid contents were assayed by pre-column derivatization and gas chromatographic method.

RESULT

The sequenues of 5S-rRNA gene spacer regions in F. thunbergii from different habitats were same, and the length of them was 588 bp. They had same content total alkaloid. The results of gas chromatography showed that they had same kinds of monomer alkaloids, but the contents of different monomer alkaloids were different.

CONCLUSION

The difference of alkaloid content in F. thunbergii from various habitats isn't resulted from base sequence variation, but from microenvironment.

The use of psychoactive substances among adolescent students in an area in the south-west of China

AIM

To survey drug/psychoactive substance use among adolescent students in a south-west province of China.

DESIGN

A cluster sample was drawn from this province of nine districts or cities. Each district/city provided two schools from grade 11 senior high school, A total of 18 schools were selected randomly.

FINDINGS

A total of 2649 students completed this self-report questionnaire, mean age 17.1 +/- 0.9 years. The response rate was 92.7-95.6% for each of the specific substances or drugs. The 'life-time prevalences of regular substance use' (at least 15 times during in any one month) were, in rank order of prevalence: tobacco 6.3%, non-steroid anti-inflammatory drugs (NSAID) 2.9%, alcohol 2.9%, solvent 0.3%, sedative/hypnotic 0.2% and cannabis 0.04%. The life-time prevalences of at least some use were: alcohol 66.1%, NSAID 59.3%, tobacco 27.4%, sedative/hypnotic 5.2%, heroin 3.1%, solvents 2.8%, amphetamine-type stimulants (ATS) 0.7% and cannabis 0.3%. The 'prevalences of current regular use' (at least 15 times in the past month) were: tobacco 4.2%, alcohol 1.6%, NSAID 0.8%, sedative/hypnotic 0.1%, solvents 0.1% and cannabis 0.1%. The 'prevalences of current use at any level' were: alcohol 15.2%, NSAID 9.6%, tobacco 7.1%, sedative/hypnotic 0.5%, solvents 0.4%, cannabis 0.1%, heroin 0.1%, and ATS 0.04%. The median age at onset substance use was between 10.7 and 13.4 9.6%.

CONCLUSIONS

Drug misuse has appeared among teenage students in this area. The most widely used substances were alcohol and cigarettes. The rates of solvent, tobacco and alcohol use among males were substantially higher than in females.

A novel method for correlating internal and external structure of individual myelinated nerve fibres

A new method is described that enables longitudinal and cross sections of an individual nerve fibre to be cut at multiple specified sites along the fibre by the use of a unique marker system. In this way the internal structure of the fibre can be correlated with the external appearance. Individual myelinated nerve fibres are teased apart in epoxy resin and mounted onto a carbon-coated slide, and after orientation and marking of specific sites of interest are snap frozen to liberate the orientated and marked fibres for embedding on the surface of an epoxy resin block for subsequent longitudinal or transverse sectioning. This method is particularly useful for the correlative study of the myelin-axon relationships.

High-throughput analysis in drug discovery: application of liquid chromatography/ion-trap mass spectrometry for simultaneous cassette analysis of alpha-1a antagonists and their metabolites in mouse plasma

The application of liquid chromatography/ion-trap mass spectrometry for simultaneous quantification of multiple drugs and detection of their metabolites for in vitro experiments was reported recently. In the current study, the use of these techniques was extended to in vivo pharmacokinetic (PK) studies of alpha-1a antagonists. In combination with limited time-point PK, greatly increased throughput was demonstrated for the in vivo screening and investigation of in vivo-in vitro correlation. In addition to quantitative analyses, the technique allowed simultaneous detection of major in vivo metabolites without having to reanalyze the plasma samples. The drugs were individually dosed in mice intravenously via tail vein injection and the blood samples were collected 5 min and 2 h after dosing. After the plasma samples for the different drugs had been prepared separately, they were pooled for cassette analysis. The concentrations of five test compounds in the plasma samples at 2 h ranged from 36-1062 ng/mL, whereas their 5-min plasma levels were similar. From the same cassette analysis, major metabolites in the samples were also detected simultaneously through the interpretation of full-scan mass spectra. The metabolite identification confirmed the results from a previous report that the major sites of metabolism are hydroxylation of the phenyl ring not bearing the alkylsulfonamide substitutent, piperidine N-dealkylation, and N-demethylation of the alkylsulfonamide group.

Factors affecting ammonia volatilisation from a rice-wheat rotation system

Some of the major factors influencing ammonia volatilisation in a rice wheat rotation system were studied. A continuous airflow enclosure method was used to measure NH3 volatilisation in a field experiment at an agricultural college in Jiangsu Province. The five treatments comprised application rates of 0, 100, 200 or 300 kg N ha(-1) as urea, per growing season with rice straw amendment when wheat was sown, and 200 kg N ha(-1) without rice straw amendment. There were three replicates in a randomised block design. Ammonia volatilisation was measured immediately after urea application in the three consecutive years 1995 to 1997. The results show that N losses through NH3 volatilisation accounted for 4-19% of N applied during the wheat growing season and for 5-11% during the rice growing season. Ammonia volatilisation was affected significantly by soil moisture and temperature before and after fertiliser application during the wheat growing season. The ratio of volatilised NH3-N to applied N after urea application during the rice growing season was as follows: top-dressing at the onset of tillering > top-dressing at the start of the booting stage > basal fertilization. The results also show that the amount of N lost through NH3 volatilisation increased with increasing N application rate, but the ratio to applied N was not affected significantly by N application rate. Amendment with rice straw had no significant effect on NH3 volatilisation.

Nitrous oxide and dinitrogen emissions from soil under different water regimes and straw amendment

In a laboratory study, soil amended with and without wheat straw (2.8 g kg(-1) soil) was incubated under 70% water holding capacity (WHC), continuously flooded and flooded/drained cycle conditions at 30 degrees C for 51 days. Dinitrogen and N2O evolution and ammonia volatilisation were measured during the incubation. Extractable NH4+-N and NO3--N were determined at the end of the incubation. Entrapped N2, N2O, and dissolved NH4+-N and NO3--N in drainage water were measured in the flooded/drained cycle treatment when the floodwater was drained. The results indicated that N loss through ammonia volatilisation was undetected in all treatments due to the low soil pH value (pHH2O= 5.87) and no air movement. The recovery of urea-15N as N2 was lowest in the continuously flooded treatments (0.75% and 0.96% with and without straw amendment, respectively), highest in the 70% WHC treatments (5.65% and 4.41%, respectively), and intermediate in the flooded/drained cycle treatments (1.79% and 2.65%, respectively). The recovery of urea-15N as N2O was in the same order as that of N2, negligible in the continuously flooded treatments, 0.01% and 0.07% in the flooded/drained cycle treatments, and 1.29% and 2.23% in the 70% WHC treatments, respectively. Peak N2O evolution rates were observed after the floodwater was drained but no substantial evolution was found after the soil was reflooded following drained periods. However, peak N2 evolution rates were observed after the onset of both drainage and re-flooding. Considerable quantities of N2 but no detectable N2O were entrapped in the flooded soil.

Resistance to TNF-induced cytotoxicity correlates with an abnormal cleavage of cytosolic phospholipase A2

To investigate the mechanism underlying the absence of arachidonic acid (AA) release by TNF in TNF-resistant cells, we first performed comparative analysis of phospholipid pools in both TNF-sensitive (MCF7) and their equivalent resistant cells (C1001). Quantification and incorporation studies of [(3)H]AA indicated that TNF-resistant cells were not depleted in AA. Furthermore, distribution of this fatty acid in different phospholipid pools was similar in both sensitive cells and their resistant counterparts, ruling out a defect in phospholipid pools. Since phospholipase A(2) (PLA(2)) are the main enzymes releasing free AA, we investigated their relative contribution in the acquisition of cell resistance to TNF-induced cell death and AA release. For this purpose, we used two PLA(2) inhibitors, methylarachidonyl fluorophosphate (MAFP) and bromoenol lactone (BEL), which selectively and irreversibly inhibit the cytosolic PLA(2) (cPLA(2)) and the Ca(2+)-independent PLA(2), respectively. Although a significant inhibitory effect of MAFP on both TNF-induced AA release and PLA(2) activity in MCF7 was observed, BEL had no effect. The inhibitory effect of MAFP on cPLA(2) activity correlated with an inhibition of TNF-induced cell death. Western blot analysis revealed that TNF induced a differential cleavage of cPLA(2) in TNF-sensitive vs TNF-resistant cells. Although the p70 (70-kDa) form of cPLA(2) was specifically increased in TNF-sensitive cells, a cleaved form, p50 (50 kDa), was selectively observed in TNF-resistant C1001 cells in the presence or absence of TNF. These findings suggest that the acquisition of cell resistance to this cytokine may involve an abnormal cPLA(2) cleavage.

Effects of lipopolysaccharide on oligodendrocyte progenitor cells are mediated by astrocytes and microglia

Oligodendrocytes are the primary cells injured in periventricular leukomalacia (PVL), a predominant form of brain white matter lesion in preterm infants. To explore the possible linkage between white matter injury and maternal infection, purified rat O-2A progenitor (Oligodendrocyte-type 2 astrocyte progenitor) cell cultures were used as a model in studying the effects of lipopolysaccharide (LPS), an endotoxin, on survival and differentiation of oligodendrocytes and the involvement of other glial cells in the effects of LPS. O-2A progenitor cells were cultured from optic nerves of 7-day-old rat pups in a chemically defined medium (CDM). Astrocyte and microglia cell cultures were prepared from the cortex of 1-day-old rat brains in the CDM. Direct treatment of LPS (1 microg/ml) to O-2A cells had no effect on viability or differentiation of these cells. When O-2A progenitor cells were cultured in the conditioned medium obtained from either astrocyte or microglial cell cultures for 48 hr, survival rate and differentiation of O-2A cells into mature oligodendrocytes were greatly enhanced as measured by the MTT assay and immunocytochemistry. The conditioned medium obtained from astrocytes or microglia treated with LPS for 48 hr, however, failed to show such a promotional effect on viability and differentiation of O-2A cells. When 5 microg/ml LPS was used to stimulate astrocytes or microglia, the conditioned medium from these glial cell cultures caused O-2A cell injury. The overall results indicate that astrocytes and microglia may promote viability and differentiation of O-2A progenitor cells under physiological conditions, but they may also mediate cytotoxic effects of LPS on oligodendrocytes under an infectious disease biochemical environment.

An experimental study on the developmental malformations of the trisomy 18 NMRI mice

OBJECTIVE

To study the incidence of trisomy 18 in NMRI mice and its developmental malformations.

METHODS

Sixty female NMRI mice and 11 male mice with the Rb(2.18) 6 Rma and Rb (1 +/-18) 10 Rma chromosomes were used. On the gestational days 16 and 17, the pregnant mice were randomly killed by cervical dislocation. A total of 823 implants were gained from 60 litters; they comprised 569 living foetuses, and chromosomal examination was performed in the generated living foetuses. Gross morphological study was performed in all living fotuses.

RESULTS

Ninety-five foetuses were identified as trisomic foetuses in all of 569 living foetuses. Among them, there were 68 trisomy 18 NMRI mice with cleft palate. Gross morphological study showed that trisomy 18 foetuses had significant body flexion. Some cases of trisomy 18 showed shortened limbs, oedematous body or exencephaly as additional symptoms.

CONCLUSION

Developmental malformations in trisomy 18 NMRI mice showed a seried of abnormalities; they had not only the underdeveloped body weight, but also the highter incidence of congenital cleft palate.

[Studies on the correlation between production of L-malic acid and some cytosolic enzymes in the L-malic acid producing strain Aspergillus sp. N1-14]

The cytosol enzymatic study in the case of high L-malic acid(LMA) production of Aspergillus sp. N1-14' was reported. The activities of 4 kind enzymes that catalyse the CO2 fixation reactions have been detected, which are pyruvate carboxylase(PC), phosphoenolpyruvate carboxlase (PEPC), phosphoenolpyurvate carboxykinase(PCK) and malic enzyme(ME). With the exception of ME, the linear correlation was found between activities of three carboxlases and the production rate of LMA. The activity of malate dehydrogenase(MDH) was at the level of 2-3 exponential higher than that of the other analysed enzymes, while the activity of succinate dehydrogenase(SDH) was much lower, and as a discrepancy, SDH was in a positive correlation to the content of LMA in fermenting slurry(r = 0.9252). It is shown that the accumulated LMA acted as an activator of SDH. Through dynamic study, it is found that, in contrast with the slow and even increase of biomass, the content of cytosol protein(Cp) sharply fluctuated mainly due to the changes of aeration conditions. The data of the linear correlation coefficients(r) of activities of cytosol enzymes to Cp(PC r = 0.9563, PEPC r = 0.7688, PCK r = 0.7300, MDH r = 0.3920, SDH r = -0.2086) exhibited an inner law of protein synthesis. Experiment of increasing the amount of spore inoculum resulted in increase of LMA and decrease of SA. After fermenting 120 h in a 5 L stirred fermentor, with 3-fold of original spore inoculum 105.88 g/L of LMA was achieved, the overall productivity was 0.883 g/(L.h), the converting rate of glucose to LMA was 78.43%. This result supports the exist of a inner law of protein synthesis in the early period of LMA fermentation by Aspergillus sp. N1-14'.

Haploinsufficiency of AML1 affects the temporal and spatial generation of hematopoietic stem cells in the mouse embryo

The AML1:CBFbeta transcription factor complex is essential for definitive hematopoiesis. Null mutations in mouse AML1 result in midgestational lethality with a complete lack of fetal liver hematopoiesis. While the cell autonomous nature and expression pattern of AML1 suggest an intrinsic role for this transcription factor in the developing hematopoietic system, no direct link to a functional cell type has been made. Here, we examine the consequences of AML1 loss in hematopoietic stem cells (HSC) of the mouse embryo. We demonstrate an absolute requirement for AML1 in functional HSCs. Moreover, haploinsufficiency results in a dramatic change in the temporal and spatial distribution of HSCs, leading to their early appearance in the normal position in the aorta-gonad-mesonephros region and also in the yolk sac.

Freshly isolated astrocyte (FIA) preparations: a useful single cell system for studying astrocyte properties

Astrocytes are cell constituents of the mammalian CNS whose intricate relationships with neurons, blood vessels and meninges in situ are well documented. These relationships and their complex morphologies imply numerous functions. Over the past quarter century or so, however, the main experimental basis for determining which roles are likely have been derived from studies on primary astrocyte cultures, usually prepared from neonatal rodent brains. We list a number of examples where these cultures have shown quantitative and qualitative differences from the properties exhibited by astrocytes in situ. The absence of an adequate reliable database makes proposals of likely hypotheses of astrocyte function difficult to formulate. In this article we describe representative studies from our laboratory showing that freshly isolated astrocytes (FIAs), can be used to determine the properties of astrocytes that seem more in concordance with the properties exhibited in situ. Although the cells are most easily isolated from < or =15 day old rat hippocampi they can be isolated from up to 30 day old rats. The examples we describe are that several different types of K(+) currents can be determined by patch clamp electrophysiology, of all the mGluRs only mGluR3 and 5 were detected by single cell RT-PCR, and that single cell Ca(2+) imaging shows that the mGluR5 receptor is functional. It was found that the frequency of cells expressing mGluR5 declines with the age of the animal with the mGluR5b type splice variant replacing the mGluR5a type, as occurs in the intact brain. It is concluded that FIAs can be used to determine the individual characteristics of astrocytes and their properties without the problems of indirect effects inherent in a heterogeneous system such as the slice, and without the problem of cultures unpredictably reflecting the in situ state. The FIAs obviously cannot be used to study interactions of astrocytes with the other CNS components but we propose that they will provide a good database on which hypotheses regarding such interactions can be tested in slices. FIAs can also be isolated from brain slices or intact brain after various pharmacological or electrophysiological perturbations to determine the changes in astrocyte properties that correlate with the perturbations.

[Morphometrical study on the development of the trisomy-18 with cleft palate and euploid mice]

OBJECTIVE

To quantitatively compare the whole body, the lateral maxillofacial profile in Ts18 foetuses with cleft palate (Ts + CP) and euploid foetuses in order to answer the question whether this animal model is associated with maldevelopment or hypoplasia of the craniomaxillofacial region.

METHODS

Sixty female Hanmice and 11 male mice with the Rb(2.18) 6Rma and Rb(1.18) 10Rma chromosomes were used to generate 569 living foetuses. Of these, 52 pairs Ts + CP and euploid foetuses were selected according to about equal body weight, and used in gross morphometric study.

RESULTS

Ts + 18 foetuses had greater body flexion, a significant maxillary and mandibular retrusion, also mandible in Ts + CP foetuses were smaller than in euploids without cleft.

CONCLUSIONS

This animal model of congenital cleft palate developed hypoplasia of the maxilla and mandible.

Regulation of transporter associated with antigen processing by phosphorylation

The ATP-binding cassette transporter associated with antigen processing (TAP) is required for transport of antigenic peptides, generated by proteasome complexes in the cytoplasm, into the lumen of the endoplasmic reticulum where assembly with major histocompatibility complex class I molecules takes place. The TAP transporter is a heterodimer of TAP1 and TAP2. Here we show that both TAP1 and TAP2 are phosphorylated under physiological conditions. Phosphorylation induces formation of high molecular weight TAP complexes that contain TAP1, TAP2, tapasin, and class I heterodimers. In addition, a 43-kDa phosphoprotein, which appears to be a kinase, is contained in the phosphorylated TAP-containing complexes. Phosphorylated TAP complexes are able to bind peptides and ATP, however, they are not capable of transporting peptides. After de-phosphorylation, TAP complexes regain the ability to transport peptides. Interestingly, phosphorylation levels of TAP complexes induced by viral infection inversely correlates with a significant reduction in TAP-dependent peptide transport activity. Enhanced TAP phosphorylation appears to be one of several strategies that viruses have exploited to better escape from host immune surveillance. These results demonstrate that major histocompatibility complex class I antigen processing and presentation is modulated by reversible TAP phosphorylation, and implicate the importance of TAP phosphorylation in the regulation of cytotoxic immune response.

cAMP-dependent protein kinase inhibits mGluR2 coupling to G-proteins by direct receptor phosphorylation

One of the primary physiological roles of group II and group III metabotropic glutamate receptors (mGluRs) is to presynaptically reduce synaptic transmission at glutamatergic synapses. Interestingly, previous studies suggest that presynaptic mGluRs are tightly regulated by protein kinases. cAMP analogs and the adenylyl cyclase activator forskolin inhibit the function of presynaptic group II mGluRs in area CA3 of the hippocampus. We now report that forskolin has a similar inhibitory effect on putative mGluR2-mediated responses at the medial perforant path synapse and that this effect of forskolin is blocked by a selective inhibitor of cAMP-dependent protein kinase (PKA). A series of biochemical and molecular studies was used to determine the precise mechanism by which PKA inhibits mGluR2 function. Our studies reveal that PKA directly phosphorylates mGluR2 at a single serine residue (Ser(843)) on the C-terminal tail region of the receptor. Site-directed mutagenesis combined with biochemical measures of mGluR2 function reveal that phosphorylation of this site inhibits coupling of mGluR2 from GTP-binding proteins

[Comparative histomorphological study on the craniomaxillary development of the trisomy-18 with cleft palate and euploid mice]

OBJECTIVE

The aim of this study is to compare histological morphology of craniomaxillary complex of Trisomy 18 with cleft palate (Ts + CP) and euploid mouse foetuses to understand whether cleft palate is associated with maldevelopment of the craniomaxillary complex or with hypoplasia of the adjacent tissues.

METHODS

Thirty pairs of Ts + CP and euploid mouse foetuses with about equal body weight were selected, and sixty craniomaxillary complex were precisely orientated in the coronal plane, then serially sectioned with 7 microns thickness through the primary palate, the whole hard palate and the soft palate. Finally six sections were selected for comparative histomorphological study based on anatomical landmarks.

RESULTS

The trisomy with cleft palate mouse foetuses had significantly developmental hypoplasia in the primary palatal shelves. The palatal shelves, vomer, palatal bone and nasal septal cartilage in cleft samples showed significantly developmental hypoplasia with a relatively wider nasal septum, nasal capsule and a bigger nasal airway volume, nasopharyngeal cavity.

CONCLUSION

The hard tissues of the craniomaxillary complex in Ts + CP mouse foetuses, including bone and cartilage show serious maldevelopment or developmental hypoplasia, and these may be closely related to the autosomal trisomic condition.