[Prognostic influence of parapharyngeal space involvement in nasopharyngeal carcinoma]

OBJECTIVE

To explore the prognostic influence of parapharyngeal space involvement in nasopharyngeal carcinoma (NPC).

METHODS

From Jan. 1987 to Dec. 1994, 197 previously untreated NPC patients were examined by CT scan. The prognostic factors ware evaluated by univariate and multivariate analyses on SPSS 8.0 software.

RESULTS

The actual survival rate, disease-free survival rate and local failure-free rate were negatively affected by the presence of parapharyngeal space involvement (P = 0.0115, P = 0.0035, P = 0.0367). The 5-year actual survival rate, disease-free survival rate and local failure-free rate in patients without tumor invasion to parapharyngeal space was 87.9%, 88.0% and 96.9%, respectively. The survival rate in patients with tumor invasion to prestyloid space was 75.0%, 71.2% and 93.7%, respectively. That in patients with tumor invasion to poststyloid space was 60.5%, 57.7% and 86.8%, respectively. The 5-year distant metastasis-free survival rate was 88.1% in patients without poststyloid involvement as compared to 73.8% in those with poststyloid involvement.

CONCLUSION

The survival and local tumor control are affected by parapharyngeal space involvement. Distant metastasis is more likely to occur when the tumor growth involves poststyloid space.

[Evaluation on the cytotoxicity of Gallium alloy by MTT-assay]

OBJECTIVE

To test the cytotoxicity of Gallium alloy, a new mercury-free dental restorative material.

METHODS

L-929 mouse fibroblasts were used to detect the cell relative proliferation rate of Gallium alloy and high-copper amalgam by MTT-assay.

RESULTS

The results indecated that the relative growth rate induced by Gallium alloy was high (93.0% +/- 4.9% 2ds, 102.0% +/- 3.5% 4ds, 107.2% +/- 4.2% 7ds), and the cytotoxicity of Gallium alloy was 0 grade according to the Test Standard of Shanghai Medical Biomaterial, meaning Gallium alloy had no significant cytotoxicity and the relative growth rate of Gallium alloy was higher than that of high-copper amalgam. The high-copper amalgam showed medium cytotoxicity.

CONCLUSION

Gallium alloy has no significant cytotoxicity.

Mechanisms of wood degradation by brown-rot fungi: chelator-mediated cellulose degradation and binding of iron by cellulose

Iron, hydrogen peroxide, biochelators and oxalate are believed to play important roles in cellulose degradation by brown-rot fungi. The effect of these compounds in an 'enhanced' Fenton system on alpha-cellulose degradation was investigated specifically in regard to molecular weight distribution and cellulose-iron affinity. This study shows that the degradative ability of an ultrafiltered low molecular weight preparation of chelating compounds isolated from the brown-rot fungus Gloeophyllum trabeum (termed 'Gt chelator') increased with increasing Gt chelator concentration when the FeIII to Gt chelator ratio was greater than about 30:1. When this ratio was less than 30:1, increasing Gt chelator concentration did not accelerate cellulose degradation. In excess hydrogen peroxide, cellulose degradation increased and then decreased with increasing iron concentration when FeIII was present in excess of the Gt chelator. The critical ratio of FeIII to Gt chelator varied depending on the concentration of hydrogen peroxide in the system. Increasing iron concentration above a critical iron:chelator ratio inhibited cellulose degradation. The optimum pH for cellulose degradation mediated by Gt chelator was around 4.0. A comparison of the effects of 2,3-DHBA (a chelator that reduces iron similarly to Gt chelator) and Gt chelator with respect to cellulose degradation demonstrated the same pattern of cellulose degradation. Cellulose-iron affinity studies were conducted at three pH levels (3.6, 3.8, 4.1), and the binding constants for cellulose-FeIII, cellulose-FeII and cellulose-FeIII in the presence of Gt chelator were calculated. The binding constants for cellulose-FeIII at all three pH levels were much higher than those for cellulose-FeII, and the binding constants for cellulose-FeIII in the presence of Gt chelator were very close to those for cellulose-FeII. This is probably the result of FeIII reduction to FeII by Gt chelator and suggests that chelators from the fungus may be able to sequester iron from cellulose and reduce it in near proximity to the cellulose and thereby better promote depolymerization. The free radical generating system described has potential for use in a variety of industrial processing and pollution control applications.

Ultraviolet radiation-induced photoproducts in human skin DNA as biomarkers of damage and its repair

We have developed a 32P-postlabelling method for quantifying ultraviolet irradiation (UV)-induced cyclobutane dimers and 6-4 photoproducts in human skin in situ. We review the application of the method in studies with human volunteers, demonstrating dose-response relationships over a wide range of administered doses, repair kinetics of UV-damaged DNA among healthy individuals and melanoma patients, and modulation by sunscreens, tan and constitutive pigmentation of damage induction. A notable finding is the wide interindividual variation in DNA damage immediately after irradiation and in its repair. Moreover, the protective effects of sunscreens against erythema and DNA damage also show wide interindividual variation. These results cannot be explained by variation in the experimental methods used. The worst-case scenario is that the differences between individuals are multiplicative, resulting in 1000-fold differences in sensitivity in the population, which would be likely to translate into differences in risk of skin cancer.

[Effect of Zn2+, Cd2+ and their combined on Ca, Fe and Mn uptake by wheat seedlings]

The effect of Zn, Cd and their combination on Ca, Fe and Mn uptake by wheat seedlings was studied with solution culture. The result shows the Zn and Cd contents of wheat increased with increasing concentrations of Zn2+ and Cd2+ in solution, while there was a difference between single and compound treatments. Zn affected Cd uptake by wheat, and Cd inhibited Zn uptake. The uptake of Ca and Mn reduced with the increase of Zn2+ and Cd2+ in solution. The uptake of Fe increased with increasing Zn2+ and Cd2+ concentrations in single treatment, while decreased in compound treatment. The interactive effect of Zn and Cd was also related to the parts of plants.

[Studies on the immobilized penicillin acylase on polymer beads]

The extracellular penicillin acylase from Bacillus megaterium was immobilized on oxirane group of Eupergit C beads. The apparent activity of the immobilized enzyme was about 1400 u.g-1 (dry weight). The optimal pH and temperature were 8.0 and 55 degrees C for hydrolytic reaction of penicillin G, respectively. The immobilized enzyme was stable in the pH range of 6.0-8.5 and at temperature below 45 degrees C. The apparent Michaelis constant for penicillin G was inhibition constant of phenylacetic acid as competitive 2 x 10(-2) mol.L-1 and Vm was 1.33 mmol.g-1 min-1 (dry weight) at 37 degrees C and PH8.0. The inhibitor and 6-APA as non-competitive inhibitor were 2.8 x 10(-2) mol.L-1 and 0.125 mol.L-1 for the immobilized enzyme at pH 8.0 and 37 degrees C, respectively. The remained activity of the immobilized enzyme was about 80% after operating 200 times for hydrolysis of penicillin G to 6-APA, and the average yield of 6-APA was 89.48%.

[Expressions of vascular endothelial growth factor and basic fibroblast growth factor in nasal polyp and its role]

OBJECTIVE

To evaluate the role of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor(bFGF) in the pathophysiology of nasal polyp.

METHODS

Thirty-nine patients with nasal polyp were divided into two groups: group A(representing type 1 and type 2 phase 1-2) and group B (representing type 2 phase 3 and type 3). The expression of VEGF and and bFGF in both groups were studied with immunohistochemical method.

RESULTS

VEGF and bFGF were not detected in norms. The detection rates of VEGF and bFGF were 59%, 41%, and 71%, 80% in group A and group B respectively. The positive rate and the number of positive cells were higher significantly in group B than that in group A. VEGF and bFGF were located mainly in the inflammatory cells and epithelial cells around the basilar membrane and inflammatory cells and endothelial cells around the vessel.

CONCLUSIONS

The overexpression of VEGF and bFGF in nasal polyp may contribute to the growth of vessels, accumulation of inflammatory cells, as a result, to enhance the development of nasal polyposis. This phenomenon maybe an important histological mark distinguishing ordinary polyp from polyposis.

Angiogenesis inhibition in the in vivo antineoplastic effect of manumycin and paclitaxel against anaplastic thyroid carcinoma

Our laboratory has investigated the anticancer effects of combined manumycin (a farnesyltransferase inhibitor) and paclitaxel (a microtubule inhibitor) against anaplastic thyroid carcinoma (ATC). In this study we reported the in vivo efficacy of this combination against ATC cells and the lack of toxicity of this treatment in mice. We observed that manumycin-treated tumors looked paler than both control and paclitaxel-treated tumors. We hypothesized that angiogenesis inhibition mediated part of the in vivo effect of manumycin. This hypothesis was supported by the findings that manumycin significantly inhibited angiogenesis (as directly demonstrated by measurement of hemoglobin content and vascular area) in Matrigel implanted into mice, that manumycin decreased the vascular endothelial growth factor in hypoxic ATC cells, and that both manumycin and paclitaxel inhibited endothelial cell proliferation. Interestingly, inhibition of endothelial tubule formation in Matrigel was enhanced by combining manumycin and paclitaxel. As angiogenesis and tumor growth are continuous processes, we investigated the effect of sustained delivery of manumycin and found that paclitaxel plus slow release manumycin (13.25 mg/kg x week) inhibited ATC xenografts more than paclitaxel plus intermittent manumycin (15 mg/kg x week). In conclusion, manumycin plus paclitaxel is an effective combination against ATC, and inhibition of angiogenesis plays a role in the antineoplastic effect of this combination.

Self-assembled monolayers from a designed combinatorial library of de novo beta-sheet proteins

A variety of naturally occurring biomaterials owe their unusual structural and mechanical properties to layers of beta-sheet proteins laminated between layers of inorganic mineral. To explore the possibility of fabricating novel two-dimensional protein layers, we studied the self-assembly properties of de novo proteins from a designed combinatorial library. Each protein in the library has a distinct 63 amino acid sequence, yet they all share an identical binary pattern of polar and nonpolar residues, which was designed to favor the formation of six-stranded amphiphilic beta-sheets. Characterization of proteins isolated from the library demonstrates that (i) they self assemble into monolayers at an air/water interface; (ii) the monolayers are dominated by beta-sheet secondary structure, as shown by both circular dichroism and infrared spectroscopies; and (iii) the measured areas (500- 600 A(2)) of individual protein molecules in the monolayers match those expected for proteins folded into amphiphilic beta-sheets. The finding that similar structures are formed by distinctly different protein sequences suggests that assembly into beta-sheet monolayers can be encoded by binary patterning of polar and nonpolar amino acids. Moreover, because the designed binary pattern is compatible with a wide variety of different sequences, it may be possible to fabricate beta-sheet monolayers by using combinations of side chains that are explicitly designed to favor particular applications of novel biomaterials.

Covalent inhibition revealed by the crystal structure of the caspase-8/p35 complex

Apoptosis is a highly regulated process that is crucial for normal development and homeostasis of multicellular organisms. The p35 protein from baculoviruses effectively prevents apoptosis by its broad-spectrum caspase inhibition. Here we report the crystal structure of p35 in complex with human caspase-8 at 3.0 A resolution, and biochemical and mutagenesis studies based on the structural information. The structure reveals that the caspase is inhibited in the active site through a covalent thioester linkage to p35, which we confirmed by gel electrophoresis, hydroxylamine treatment and mass spectrometry experiments. The p35 protein undergoes dramatic conformational changes on cleavage by the caspase. The repositioning of the amino terminus of p35 into the active site of the caspase eliminates solvent accessibility of the catalytic dyad. This may be crucial for preventing hydrolysis of the thioester intermediate, which is supported by the abrogation of inhibitory activity through mutations at the N terminus of p35. The p35 protein also makes conserved contacts with the caspase outside the active-site region, providing the molecular basis for the broad-spectrum inhibitory activity of this protein. We demonstrate a new molecular mechanism of caspase inhibition, as well as protease inhibition in general.

Continuous crystalline carbonate apatite thin films. A biomimetic approach

In contrast to extensive studies on hydroxyapatite thin films, very little has been reported on the thin films of carbonated apatite (dahllite). In this report, we describe the synthesis and characterization of a highly crystalline dahllite thin film assembled via a biomimetic pathway. A free-standing continuous precursor film of carbonated calcium phosphate in an amorphous phase was first prepared by a solution-inhibited templating method (template-inhibition) at an air-water interface. A stearic acid surface monolayer acted as the template, while a carbonate-phosphate solution composed a binary inhibition system. The precursor film formed at the air/water interface was heated at 900 degrees C and transformed into a dense crystalline film that retained the overall shape of the precursor. The crystalline phase was characterized by XRD and IR to be a single-phase carbonate apatite, with carbonate substitutions in both type A (OH-) and type B (PO4(3-)) lattice positions.

Inhibition of corticotropin releasing hormone type-1 receptor translation by an upstream AUG triplet in the 5' untranslated region

The influence of an upstream open reading frame (ORF) in the 5'-untranslated region (UTR) of the mRNA on corticotropin-releasing hormone receptor type 1 (CRHR1) translation was studied in constructs containing the 5'-UTR of CRHR1, with or without an ATG-to-ATA mutation in the upstream ORF, and the main ORF of luciferase or CRHR1. Upstream mutation in luciferase constructs increased luciferase activity when transfected into COS-7 or AtT20 cells compared with the native 5'-UTR. Transfection of CRHR1 constructs containing the upstream mutation into AtT20 or LVIP2.0zc reporter cells, resulted in higher (125)I-Tyr-oCRH binding and corticotropin-releasing hormone-stimulated cAMP production, without changes in CRHR1 mRNA levels (measured by RNase protection assay). In vitro translation of luciferase or CRHR constructs with or without mutation of the upstream ATG, and Western blot analysis with anti-luciferase and anti-CRHR1 antibodies confirmed that mutation of the upstream ATG increases translation of the main ORF. The mechanism by which the upstream ORF inhibits translation may involve translation of the upstream peptide, because in vitro translation, or transfection into LVIP2.0zc cells of a fusion construct of the upstream ORF and green fluorescent protein (GFP) yielded a band consistent with the molecular size of GFP protein. The study shows that the upstream AUG in 5'-UTR of CRHR1 mRNA inhibits receptor expression by inhibiting mRNA translation and suggests the short open reading frame in the 5'-UTR plays a role in regulating translation of the CRH receptor.

[Change of inhabitant dietary pattern in Shandong province during 1988-1997]

Food consumption data of some bigger cities and towns of Shandong province during 1988-1997 had been collected and analyzed. The results showed that the consumption of cereals and vegetable in 1997 tended to be decreased and the consumption of meat, egg, fruit and milk in 1997 tended to be increased. The desirable dietary pattern (DDP) scores for cities and towns were 82.5, 78.7 in 1988, and 93.3, 88.4 in 1997 respectively. All these changes indicated that the dietary quality improved markedly but the consumption of bean and milk are not enough.

Novel 2,5-hexanedione analogues. Substituent-induced control of the protein cross-linking potential and oxidation susceptibility of the resulting primary amine-derived pyrroles

The neurotoxic gamma-diketone, 2,5-hexanedione (2,5-HD), induces neurofilamentous swellings at prenodal sites in proximal axons as a consequence of pyrrolation of lysine epsilon-amino groups on neurofilament proteins. However, there is disagreement as to whether pyrrole formation and the associated alteration of noncovalent interactions is sufficient to cause neurofilament accumulation, or whether pyrrole autoxidation and subsequent protein-protein cross-linking is an obligatory event. To investigate gamma-diketones that might form pyrroles inert to autoxidative-induced cross-linking, we synthesized 1,1,1-trifluoro-2,5-hexanedione, 3-(trifluoromethyl)-2,5-hexanedione (3-TFMHD), and two 3-(dialkylaminocarbonyl)-2,5-diketones and assessed their rates of pyrrole formation with amines, the oxidation susceptibility of the resulting pyrroles, and the protein cross-linking potential in vitro, relative to those of 3-methyl-2,5-hexanedione. 1,1,1-Trifluoro-2,5-hexanedione does not form pyrroles, but the three 2,5-HD analogues with an electron-withdrawing 3-substituent all rapidly formed pyrroles that were inert to autoxidation. Although 3-TMFHD nonetheless still induced cross-linking of ribonuclease A, by a nonoxidative mechanism independent of the pyrrole, the two 3-(dialkylaminocarbonyl)-2,5-diketones did not exhibit any protein cross-linking. As these two gamma-diketones possess aqueous-organic partitioning properties similar to those of 2,5-HD, they should serve as useful mechanistic probes in further studies.

[Research on fibrotic effect of Ni-Ti and 317L alloys in esophagus]

This study was conducted to examiune the fibrotic effect of Ni-Ti and 317L alloys in esophagus. The extract fluid from Ni-Ti, 317L alloys was made according to the ASTM standards of U.S.A. The Fb of esophageal scar was cultured primarily, then incubated with alloy abstract fluid. The proliferating activity of Fb was measured by MTT at 4, 24, 48, 72 hours in the course of culturing. The esophagus embedding test of Ni-Ti, 317L alloys was made according to ASTM standards of U.S.A. The tissue around the alloys was taken at weeks 2 and 12, and the pathologic changes were analysed. The results showed that Ni-Ti, 317L extract could depress the proliferating function of Fb gently, and the depressing action increased gradually with the culturing time. The result of embedding test was in accord with the ASTM standards of U.S.A. completely; the fibrotic membrane around the NiTi, 317L alloys became thinner with embedding time. These findings suggested that the scattering composition of Ni-Ti, 317L in body fluid might not activate the proliferating and secreting function of Fb, and the two alloys could not lead to fibrosis of esophagus aroun them.

[Lymphocyte subpopulation, interleukin-2 and high affinity interleukin-2 receptor expression in primary nephrotic syndrome]

OBJECTIVE

To understand the cellular immune response during relapse and remission stage in primary nephrotic syndrome (PNS).

METHODS

We applied the radioligand binding assay (RBA), the bioactivity measurement of IL-2, and monoclonal antibody sensitized red blood cell method to evaluate the expression of IL-2R, the production of IL-2 and T lymphocyte subsets of PBMC from 22 patients suffering from PNS, 17 patients with PNS in remission, and 25 normal subjects matched age and sex.

RESULTS

CD3, CD4, CD8, IL-2, IL-2R in relapse were significantly lower than those in control (P < 0.05); all above except CD8 in remission patients were significantly higher than those in relapse, but lower than those in control (P < 0.05).

CONCLUSION

This study suggested that the cell mediated immunity (CMI) during acute nephrotic phase decreased; the deficiency of CMI of PNS in remission improved a lot when compared with the acute phase, but still not recovered completely; the deficiency of CMI with PNS in remission might be one of the causes of easily recurring of PNS.

Experimental study of the morphology of cerebral bridging vein

OBJECTIVE

To investigate the morphological properties of pig cerebral bridging vein.

METHODS

The morphology and fibre arrangement of 15 cerebral bridging veins obtained from 7 Danish Yorkshire landrace pigs were observed.

RESULTS

There was a narrow region at the junction of the cerebral bridging veins and superior sagittal sinus termed "outflow cuff segment". The diameter and length of outflow cuff segment were much smaller and the thickness was higher than those of the cerebral bridging veins ( P < 0.01), and circumferential collagen fibres were most dense in the outflow cuff segment. The opening angle of the outflow cuff segment and the cerebral bridging veins were 115 +/- 4 degrees and 120 +/- 4 degrees ( P > 0.05).

CONCLUSIONS

There were differences in fibre arrangement and morphological properties between the outflow cuff segment and the cerebral bridging vein, just like a resistance valve, the outflow cuff segment may play an important role in stabilizing cerebral venous outflow and regulating intracranial pressure.

Differences in hepatic levels of intermediates in bile acid biosynthesis between Cyp27(-/-) mice and CTX

Cerebrotendinous xanthomatosis (CTX) is a rare, recessively inherited lipid storage disease characterized by a markedly reduced production of chenodeoxycholic acid and an increased formation of 25-hydroxylated bile alcohols and cholestanol. Patients with this disease are known to have mutations in the sterol 27-hydroxylase (Cyp27) gene. However, one study showed that mice with a disrupted Cyp27 gene did not have any CTX-related clinical or biochemical abnormalities. To explore the reason, hepatic cholesterol, cholestanol, and 12 intermediates in bile acid biosynthetic pathways were quantified in 10 Cyp27(-/-) and 7 Cyp27(+/+) mice, two CTX patients (untreated and treated with chenodeoxycholic acid), and four human control subjects by high resolution gas chromatography-mass spectrometry. Mitochondrial 27-hydroxycholesterol and 5beta-cholestane-3alpha,7alpha,12alpha,27-tetrol were virtually absent in both Cyp27(-/-) mice and CTX patients. In Cyp27(-/-) mice, microsomal concentrations of intermediates in the early bile acid biosynthetic pathway (7alpha-hydroxycholesterol, 7alpha-hydroxy-4-cholesten-3-one, 7alpha,12alpha-dihydroxy-4-cholesten-3-one, and 5beta-cholestane-3alpha,7alpha,12alpha-triol), 25-hydroxylated bile alcohols (5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol, 5beta-cholestane-3alpha,7alpha,12alpha,23R,25-pentol, and 5beta-cholestane-3alpha,7alpha,12alpha,24R, 25-pentol), and cholestanol were all significantly elevated compared with those in Cyp27(+/+) mice, although the levels were lower than those in untreated CTX patients. The intermediate levels in early bile acid biosynthesis were more elevated in male (16;-86% of CTX) than in female Cyp27(-/-) mice (7-30% of CTX). In contrast, 25-hydroxylated bile alcohol concentrations were not significantly different between male and female Cyp27(-/-) mice and were considerably lower (less than 14%) than those in CTX patients.These results suggest that 1) in Cyp27(-/-) mice, especially in females, classic bile acid biosynthesis via 7alpha-hydroxycholesterol is not stimulated as much as in CTX patients; and 2) formed 25-hydroxylated bile alcohols are more efficiently metabolized in Cyp27(-/-) mice than in CTX patients.

[FTIR study of transition metal 2-acrylamido-2-methyl-1-propanesulfonates]

Compounds of transition metal ion (Cu2+, Co2+, Ni2+) 2-acrylamidomethyl-2-methyl-1-propanesulfonates were studied by FTIR and X-ray powder diffraction techniques. The FTIR spectra of Co and Ni compound are similar but are different from that of Cu compound. The results of X-ray diffraction indicated that the crystal structure of Co and Ni compound are different.

[Expression of Th1, Th2-typed cytokines and its significance in nasal polyps]

OBJECTIVE

To evaluate the possible role of cytokines in pathophysiology and treatment of nasal polyps.

METHOD

The expressions of Th1-typed cytokines IFN-gamma, IL-2, IL-12 and Th2-typed cytokines IL-4, IL-5, IL-8, IL-10, IL-13 were investigated with enzyme-linked immune sorbent assay(ELISA) in 25 patients with nasal polyps.

RESULT

There was a significant upregulation of Th2-typed cytokines IL-4, IL-5, IL-8, IL-10, IL-13 in nasal polyps compared with normal nasal mucosa, especially IL-4 and IL-5 (3.9 times and 8.8 times higher than normal mucous respectively) while the expression of Th1-typed cytokines IFN-gamma, IL-2, IL-12 decreased after treated with local glucocorticoid. The levels of Th2-typed cytokines decreased significantly and Th1-typed cytokines had no obvious change.

CONCLUSION

The upregulation of Th2-typed cytokines such as IL-4, IL-5, IL-8, IL-10, IL-12 may play an important role in the pathophysiology of nasal polyps and Th2-typed cytokines can be viewed as a target of treatment to nasal polyps.

Metabolic regulation by leucine of translation initiation through the mTOR-signaling pathway by pancreatic beta-cells

Recent findings have demonstrated that the branched-chain amino acid leucine can activate the translational regulators, phosphorylated heat- and acid-stable protein regulated by insulin (PHAS-I) and p70 S6 kinase (p70S6k), in an insulin-independent and rapamycin-sensitive manner through mammalian target of rapamycin (mTOR), although the mechanism for this activation is undefined. It has been previously established that leucine-induced insulin secretion by beta-cells involves increased mitochondrial metabolism by oxidative decarboxylation and allosteric activation of glutamate dehydrogenase (GDH). We now show that these same intramitochondrial events that generate signals for leucine-induced insulin exocytosis are required to activate the mTOR mitogenic signaling pathway by beta-cells. Thus, a minimal model consisting of leucine and glutamine as substrates for oxidative decarboxylation and an activator of GDH, respectively, confirmed the requirement for these two metabolic components and mimicked closely the synergistic interactions achieved by a complete complement of amino acids to activate p70s6k in a rapamycin-sensitive manner. Studies using various leucine analogs also confirmed the close association of mitochondrial metabolism and the ability of leucine analogs to activate p70s6k. Furthermore, selective inhibitors of mitochondrial function blocked this activation in a reversible manner, which was not associated with a global reduction in ATP levels. These findings indicate that leucine at physiological concentrations stimulates p70s6k phosphorylation via the mTOR pathway, in part, by serving both as a mitochondrial fuel and an allosteric activator of GDH. Leucine-mediated activation of protein translation through mTOR may contribute to enhanced beta-cell function by stimulating growth-related protein synthesis and proliferation associated with the maintenance of beta-cell mass.

Excretion pattern investigation of urinary normal and modified nucleosides of breast cancer patients by RP-HPLC and factor analysis method

Modified nucleosides, formed post-transcriptionally in RNA by a number of modification enzymes, are excreted in abnormal levels in the urine of patients with malignant tumors. To test their usefulness as tumor markers, and to compare them with the conventional tumor markers, a reversed-phase high-performance liquid chromatographic (RP-HPLC) method and a factor analysis method have been used to study the excretion pattern of nucleosides of breast cancer patients. A clear cut differentiation of the breast cancer group and the healthy individuals in two clusters without overlapping was obtained.

Sugar interaction with metal ions. The crystal structure and Raman spectra study of SmCl3-galactitol complex

The crystal structure of 2SmCl3.galactitol.14H2O has been determined. The crystal system is triclinic, space group: P-1. The unit cell dimensions: a = 9.683(2) A, b = 10.341(2) A, c = 7.990(2) A; alpha = 108.01(3) degrees, beta = 92.71(3) degrees, gamma = 88.42(3) degrees. Each Sm atom is coordinated to nine oxygen atoms, three from the alditol and six from water molecules, with Sm-O distance from 2.417 to 2.520 A. The seventh water molecule is hydrogen-bonded by the hydroxy hydrogen on O-3 (O(3)-H(13)...O(10), 2.635 A). After forming complexes the peaks have shifted and the relative intensities have changed in the IR and Raman spectra, which are corresponding to the changes in bond distances and bond angles of the structures. The IR and Raman spectra of Pr-, Nd- and Sm-galactitol complexes are similar, which show that the three metal ions have the same coordination mode.