Influence of AVP4-8 on MAPK activity in astrocytic glial and fetal neuronal cells in primary culture

AIM

To study the effect of argipressin (4-8) (AVP4-8) on the mitogen-activated protein kinase (MAPK) activity in astroglial culture and fetal neuronal culture from rat cerebral cortex and hippocampus. Some protein kinases involved in this signal pathway were also addressed.

METHODS

Rat brain primary cells were cultured in serum free medium or starved for 24 h before use. Cells were transferred to Ca2+ and Mg2+ free Dulbeco's phosphate buffer (D-PBS) with various drugs. MAPK activity was measured.

RESULTS

The main findings were: (1) AVP4-8 induced the MAPK activity in rat brain astroglial culture but not in fetal neuronal cultures. And this was blocked by ZDC (C) PR, an antagonist of AVP4-8. (2) PD98059, a potent selective inhibitor of MAPK/ERK kinase (MEK) and GF109203X, a specific inhibitor of protein kinase C (PKC) abolished AVP4-8-evoked MAPK activity on astrocytes.

CONCLUSION

AVP4-8 can activate the MAPK activity in astrocytes but not in fetal neuronal culture. MEK and PKC may be involved in the AVP4-8-evoked cascade.

Functional collaboration between different cyclin-dependent kinase inhibitors suppresses tumor growth with distinct tissue specificity

The presence of two families of seven distinct mammalian cyclin-dependent kinase (CDK) inhibitor genes is thought to mediate the complexity of connecting a variety of cellular processes to the cell cycle control pathway. The distinct pattern of tissue expression of CDK inhibitor genes suggests that they may function as tumor suppressors with different tissue specificities. To test this hypothesis, we have characterized two strains of double mutant mice lacking either p18(INK4c) and p27(KIP1) or p18(INK4c) and p21(CIP1/WAF1). Loss of both p18 and p27 function resulted in the spontaneous development by 3 months of age of at least eight different types of hyperplastic tissues and/or tumors in the pituitary, adrenals, thyroid, parathyroid, testes, pancreas, duodenum, and stomach. Six of these hyperplastic tissues and tumors were in endocrine organs, and several types of tumors routinely developed within the same animal, a phenotype reminiscent of that seen in combined human multiple endocrine neoplasia syndromes. The p18-p21 double null mice, on the other hand, developed pituitary adenomas, multifocal gastric neuroendocrine hyperplasia, and lung bronchioalveolar tumors later in life. G(1) CDK2 and CDK4 kinase activities were increased in both normal and neoplastic tissues derived from mice lacking individual CDK inhibitors and were synergistically stimulated by the simultaneous loss of two CDK inhibitors. This indicates that an increase in G(1) CDK kinase activity is a critical step during but is not sufficient for tumor growth. Our results suggest that functional collaborations between distinct CDK inhibitor genes are tissue specific and confer yet another level of regulation in cell growth control and tumor suppression.

[Relationships between learning and memory and expression of nov gene of rats]

During the establishment of learning and memory of adult rats with active avoidance reaction expression of nov gene, nov mRNA positive neurons and NOV protein immunoreactive neurons were found in hippocampus, cingulate cortex, globus pallidus, caudate putamen and hypothalamus. The strongest positive reaction of NOV protein was observed in high ability group of learning and memory (HALM). Basic expression was found in pseudoconditioning (PC) group. The expression of NOV protein was higher in low ability group of learning and memory (LALM) than in PC group. No significant difference was detected in nov mRNA positive reaction between the three groups. The results indicate that nov gene may play an important role in learning and memory of adult rats. This regulation occurs at the level of NOV protein translation.

Isolation and characterization of cytotoxic saponin chloromaloside A from Chlorophytum malayense

A cytotoxic steroidal glycoside was isolated from Chlorophytum malayense Ridley and its structure was characterized as a known compound, neohecogenin 3-O-beta-D-glucopyranosyl(1-->2)-[beta-D-xylopyranosyl(1-->3)]-beta-D- glucopyranosyl(1-->4)-beta-D-galactopyranoside (chloromaloside A). The structural identification was performed using 2D-NMR and LC/MS/MS analysis. The previous, erroneously assigned 1H-NMR spectral data were revised whereas the published 13C-NMR spectral assignments were confirmed. This compound showed in vitro cytotoxicity against several human cancer cell lines.

Coagulation and cytokine profile after major hepatobiliary surgery in Chinese patients

BACKGROUND/AIMS

Hypercoagulability and increased circulating cytokine levels have been separately reported after surgical operations. We investigated whether the cytokine level and postoperative coagulation profile would change similarly in Chinese patients undergoing major hepatobiliary surgery.

METHODOLOGY

Serial serum levels of IL-6, IL-1 beta and TNF-alpha were measured by colorimetric ELISA. Serial coagulation profile was measured by thrombelastography. Hemoglobin and white cell counts were also measured serially.

RESULTS

Only mild hypercoagulability was found at the 12th and 144th hours, evidenced by shortening of r-time and k-time on thrombelastography (P < 0.05). IL-6 and IL-1 beta levels were significantly raised from the 12th hour (P < 0.01) while TNF-alpha level was unchanged. From the 3rd hour to the 48th hour, there was negative correlation between IL-6 levels and various thrombelastographic parameters such as coagulation index (r = -0.777, P < 0.001); k-time (r = 0.478, P < 0.05); maximum amplitude (r = -0.688, P < 0.01) and angle (r = -0.665, P < 0.01).

CONCLUSIONS

We observed a much milder degree of hypercoagulability in Chinese patients after major hepatobiliary surgery as compared to those reported in other operations in non-Chinese patients. Unlike in sepsis where a close link between increased cytokine levels and hypercoagulability has been reported, increase in IL-6 was associated with less hypercoagulability in Chinese patients after major hepatobiliary surgery.

Crystal structure of an adenine bulge in the RNA chain of a DNA.RNA hybrid, d(CTCCTCTTC).r(gaagagagag)

Crystal structure of a DNA.RNA hybrid, d(CTCCTCTTC).r(gaagagagag), with an adenine bulge in the polypurine RNA strand was determined at 2.3 A resolution. The structure was solved by the molecular replacement method and refined to a final R-factor of 19.9% (Rfree 22.2%). The hybrid duplex crystallized in the space group I222 with unit cell dimensions, a = 46.66 A, b = 47.61 A and c = 54.05 A, and adopts the A-form conformation. All RNA and DNA sugars are in the C3'-endo conformation, the glycosyl angles in anti conformation and the majority of the C4'-C5' torsion angles in g+ except two trans angles, in conformity with the C3'-endo rigid nucleotide hypothesis. The adenine bulge is looped out and it is also in the anti C3'-endo conformation. The bulge is involved in a base-triple (C.g)*a interaction with the end base-pair (C9.g10) in the minor groove of a symmetry-related molecule. The 2' hydroxyl group of g15 is hydrogen bonded to O2P and O5' of g17, skipping the bulged adenine a16 and stabilizing the sugar-phosphate backbone of the hybrid. The hydrogen bonding and the backbone conformation at the bulged adenine site is very similar to that found in the crystal structure of a protein-RNA complex.

Crystal structure of a DNA.RNA hybrid duplex with a polypurine RNA r(gaagaagag) and a complementary polypyrimidine DNA d(CTCTTCTTC)

DNA.RNA hybrid duplexes are substrates of RNase H and reverse transcriptase. The crystal structure of a hybrid duplex, d(5'-CTCTTCTTC-3').r(5'-gaagaagag-3') (the uppercase letters indicate DNA and lowercase letters RNA), with a polypurine RNA strand and a complementary DNA strand has been determined at 1.8 A resolution. The structure was refined first at 1.9 A by XPLOR and subsequently by CNS at 1.8 A. The hybrid is found in a standard A-form conformation with all the sugars in the C3'-endo puckering. The 5'-terminal base dC of the DNA strand was clearly visible in the electron density map of the present structure, in contrast to the previously reported structure d(TTCTTBr(5)CTTC).r(gaagaagaa) where the 5'-terminal base dT was not visible, leaving the terminal rA unpaired. Thus, the comparison of the terminal base pairs, C.g versus T.a, in the two hybrid crystal structures provides information on the stability of these base pairs in hydrogen bonding (three versus two) and base stacking interactions. The differences in the terminal base pairs produce different kinks in the two structures. Minor groove widening is observed in the present structure at a distinctive kink in the lower half of the duplex, in contrast to the small widening of the minor groove and a very slight bend in the upper half of the T.a structure.

Investigation of an optical limiting mechanism in multiwalled carbon nanotubes

We report our investigation of the mechanism that is responsible for the optical limiting behavior in multiwalled carbon nanotubes. We conducted energy-dependent transmission measurements, picosecond time-resolved pump-probe experiment, and nonlinear scattering experiments at 532-nm wavelength on multiwalled carbon nanotube suspension. For comparison, C(60)-toluene solutions and carbon black suspensions were also studied in the same experiments. The similarities that we observed between the multiwalled carbon nanotubes and carbon black suspension suggest that nonlinear scattering, which is known to be responsible for the limiting action in carbon black suspension, should play an important role in the limiting effect in multiwalled carbon nanotubes.

Cloning of cytidine triphosphate: phosphocholine cytidylyltransferase mRNA upregulated by a neuropeptide arginine-vasopressin((4-8)) in rat hippocampus

Neuropeptide arginine-vasopressin((4-8)) (AVP(4-8)) is a metabolite of arginine-vasopressin which has been shown to have potent memory-enhancing activity, facilitate neurite elongation and prolongate cell aging. Identification of differentially expressed genes in hippocampus induced by AVP(4-8) is important for understanding the molecular basis of AVP(4-8) function. Differential display PCR and 5'rapid amplification of cDNA Ends were used. One new full length cDNA encoding rat cytidine triphosphate: phosphocholine cytidylyltransferase (CCT) beta was thus obtained. Northern blot analysis demonstrated that it was upregulated by AVP(4-8) in mature rat hippocampus. The study of tissue distribution with reverse transcription PCR showed that the gene was abundant in brain. Since CCT catalyzes the formation of cytidine diphosphate choline, which was reported to have a beneficial therapeutic effect on Alzheimer's disease, so we speculated that AVP(4-8) may be a potential candidate for treating Alzheimer's disease by upregulating CCT mRNA level.

Solution NMR evidence for a cis Tyr-Ala peptide group in the structure of [Pro93Ala] bovine pancreatic ribonuclease A

Proline peptide group isomerization can result in kinetic barriers in protein folding. In particular, the cis proline peptide conformation at Tyr92-Pro93 of bovine pancreatic ribonuclease A (RNase A) has been proposed to be crucial for chain folding initiation. Mutation of this proline-93 to alanine results in an RNase A molecule, P93A, that exhibits unfolding/refolding kinetics consistent with a cis Tyr92-Ala93 peptide group conformation in the folded structure (Dodge RW, Scheraga HA, 1996, Biochemistry 35:1548-1559). Here, we describe the analysis of backbone proton resonance assignments for P93A together with nuclear Overhauser effect data that provide spectroscopic evidence for a type VI beta-bend conformation with a cis Tyr92-Ala93 peptide group in the folded structure. This is in contrast to the reported X-ray crystal structure of [Pro93Gly]-RNase A (Schultz LW, Hargraves SR, Klink TA, Raines RT, 1998, Protein Sci 7:1620-1625), in which Tyr92-Gly93 forms a type-II beta-bend with a trans peptide group conformation. While a glycine residue at position 93 accommodates a type-II bend (with a positive value of phi93), RNase A molecules with either proline or alanine residues at this position appear to require a cis peptide group with a type-VI beta-bend for proper folding. These results support the view that a cis Pro93 conformation is crucial for proper folding of wild-type RNase A.

The value of in-phase and opposed-phase T1-weighted breath-hold FLASH sequences for hepatic imaging

The value of the combined in-phase (IP) and opposed-phase (OP) T1-weighted (T1-W) breath-hold FLASH sequences for hepatic imaging, especially for fat content, was evaluated. Non-contrast-enhanced IP and OP T1-W GRE breath-hold images were obtained in 76 patients refereed for abdominal MRI at 1.5T. 76 patients were divided into three groups for analysis: (1) liver without mass (n = 8); (2) liver with hepatoma (n = 34); (3) liver with haemangioma or cyst (n = 34). Liver/spleen and liver/lesion signal-to-noise (SNR) and contrast-to-noise ratio (CNR) were assessed for lesion detection. Images between IP and OP sequences were compared quantitatively. The results showed that there was not statistically significant difference in liver/spleen and liver/lesion SNR between IP and OP sequences. In the patients with fatty infiltration, the OP sequences yielded substantially lower values for liver/spleen and liver/lesion SNR than those of the IP sequences. Furthermore, OP imaging showed fatty infiltration in 14 cases and demonstrated hyperintense peritumor rim in 4 cases. In 14 cases of fatty infiltration, many lesions were identified using IP images. The use of IP and OP GRE sequences provides complementary diagnostic information for hepatic lesions and fat content. Focal hepatic lesions may be obscured in the setting of fatty infiltration if only OP sequences are employed. A complete assessment of the liver with MR should include both IP and OP imaging.

The crystal structure of a T cell receptor in complex with peptide and MHC class II

The crystal structure of a complex involving the D10 T cell receptor (TCR), 16-residue foreign peptide antigen, and the I-Ak self major histocompatibility complex (MHC) class II molecule is reported at 3.2 angstrom resolution. The D10 TCR is oriented in an orthogonal mode relative to its peptide-MHC (pMHC) ligand, necessitated by the amino-terminal extension of peptide residues projecting from the MHC class II antigen-binding groove as part of a mini beta sheet. Consequently, the disposition of D10 complementarity-determining region loops is altered relative to that of most pMHCI-specific TCRs; the latter TCRs assume a diagonal orientation, although with substantial variability. Peptide recognition, which involves P-1 to P8 residues, is dominated by the Valpha domain, which also binds to the class II MHC beta1 helix. That docking is limited to one segment of MHC-bound peptide offers an explanation for epitope recognition and altered peptide ligand effects, suggests a structural basis for alloreactivity, and illustrates how bacterial superantigens can span the TCR-pMHCII surface.

Association with cullin partners protects ROC proteins from proteasome-dependent degradation

Cullin 1/CDC53 represents a multigene family and has been linked to the ubiquitin-mediated proteolysis of several different proteins. We recently identified two closely related RING finger proteins, ROC1 and ROC2, that share considerable sequence similarity to an APC subunit, APC11, and demonstrated ROC1 as an essential subunit of CUL1 and CDC53 ubiquitin ligases. We report here that the expression of ROC1, ROC2 and APC11 genes are induced by mitogens and remain constant during the cell cycle. Unlike other subunits of SCF and APC E3 ligases, ectopically expressed ROC family proteins are degraded by a proteasome-inhibitor sensitive pathway and are stabilized by associating with cullins. Mutations at the conserved Phe79 and His80 residues in the RING finger of ROC1 diminish its binding with cullins, resulting in a loss of cullin protection and ubiquitin ligase activity. These results suggest a potential mechanism for regulating the activity of ROC-cullin ligases through complex assembly and ROC/APC11 subunit ubiquitination.

Effect of N-acetylcysteine on mitochondrial function following traumatic brain injury in rats

Efficacy of N-acetylcysteine (NAC) in traumatic brain injury (TBI)-induced mitochondrial dysfunction was evaluated following controlled cortical impact injury in rats. Respiratory function and calcium transport of rat forebrain mitochondria from injured and uninjured hemispheres were examined. NAC significantly restored mitochondrial electron transfer, energy coupling capacity, calcium uptake activity and reduced calcium content absorbed to brain mitochondrial membranes when examined 12 h post-TBI if NAC was administered i.p. 5 min before injury or 30 min or 1 h postinjury. Glutathione (reduced form, GSH) levels in brain tissues were decreased at all time points examined over a 14-day observation period, while mitochondrial GSH levels significantly decreased only at 3 days and 14 days following TBI. NAC treatment given within 1 h greatly restored brain GSH levels from 1 h to 14 days and mitochondrial GSH levels from 12 h to 14 days post-TBI. NAC did not show protective effects when given 2 h postinjury. Our data indicate that NAC administered postinjury at an early stage can effectively restore TBI-induced mitochondrial dysfunction and the protective effect of NAC may be related to its restoration of GSH levels in the brain.

In vitro and in vivo inhibition of human flavin-containing monooxygenase form 3 (FMO3) in the presence of dietary indoles

The effect of consumption of glucosinolate-containing Brussels sprouts on flavin-containing monooxygenase functional activity in humans was investigated in 10 healthy, male, non-smoking volunteers. After a 3-week run-in period, 5 volunteers continued on a glucosinolate-free diet for 3 weeks (control group), and 5 others consumed 300 g of cooked Brussels sprouts per day (sprouts group). Human flavin-containing monooxygenase activity was measured by determining the levels of urinary trimethylamine and trimethylamine N-oxide. In the control group similar trimethylamine to trimethylamine N-oxide ratios were observed, while in the sprouts group the trimethylamine to trimethylamine N-oxide ratios were increased 2.6- to 3.2-fold, and thus flavin-containing monooxygenase functional activity was decreased significantly. To investigate the molecular basis for the in vivo inhibition of functional human flavin-containing monooxygenase activity, in vitro studies were carried out examining the effect of acid condensation products of indole-3-carbinol, anticipated to be formed after transit of Brussels sprouts through the gastrointestinal system, on the prominent cDNA-expressed human flavin-containing monooxygenase form 3 enzymes. Two indole-containing materials were observed to be potent inhibitors of human flavin-containing monooxygenases, having Ki values in the low micromolar range. The results suggested that acid condensation products expected to be formed upon transit of Brussels sprouts materials through the gastrointestinal system were potent competitive inhibitors of human flavin-containing monooxygenase form 3 enzymes. The findings indicate that daily intake of Brussels sprouts may lead to a decrease in human flavin-containing monooxygenase activity, and this may have consequences for metabolism of other xenobiotics or dietary constituents.

Narcolepsy in orexin knockout mice: molecular genetics of sleep regulation

Neurons containing the neuropeptide orexin (hypocretin) are located exclusively in the lateral hypothalamus and send axons to numerous regions throughout the central nervous system, including the major nuclei implicated in sleep regulation. Here, we report that, by behavioral and electroencephalographic criteria, orexin knockout mice exhibit a phenotype strikingly similar to human narcolepsy patients, as well as canarc-1 mutant dogs, the only known monogenic model of narcolepsy. Moreover, modafinil, an anti-narcoleptic drug with ill-defined mechanisms of action, activates orexin-containing neurons. We propose that orexin regulates sleep/wakefulness states, and that orexin knockout mice are a model of human narcolepsy, a disorder characterized primarily by rapid eye movement (REM) sleep dysregulation.

Suppression of angiotensin II stimulated responses in aortic vascular smooth muscle cells of experimental cirrhotic rats

Functional responses to angiotensin II (AT-II) were determined in aortic vascular smooth muscle cells (VSMCs) from experimental cirrhotic rats. Our data showed that AT-II-stimulated extracellular acidification rate (ECAR), which was measured by Cytosensor microphysiometry, was significantly reduced in the aortic VSMCs from the cirrhotic rats as compared to those from the control animals. The ability of AT-II to promote formation of inositol phosphates, the second messenger produced by the activation of Gq-coupled receptors, was also considerably suppressed in the cirrhotic VSMCs. Furthermore, the maximal p42/44 MAPK phosphorylation stimulated by AT-II was significantly reduced in the cirrhotic VSMCs in contrast to that in the normal VSMCs. Taken together, our data clearly demonstrated that the functional responses to AT-II was severely suppressed in aortic VSMCs in cirrhosis, indicating the impairment of general Gq-coupled receptor signaling and subsequent biological function in the cirrhotic VSMCs.

[Calculation for Franck-Condon factors of the two band systems beta(B2pi(r) - X2pi(r)) and gamma(A2sigma+ - X2Pi(r)) of NO in the air at high temperature]

From the nuclear Schrödinger equation of a diatomic molecule with vibration-rotation interaction term involved in it, we derive the wavefunction relevant not only to vibrational quantum number, but also to rotational one. The Franck-Condon factors of the two band systems beta(B2pi(r) - X2pi(r)) and gamma(A2sigma+ - X2Pi(r)) of NO in the air at high temperature are calculated in this paper, using the derived wavefunction. In the calculation, the rotational quantum number J takes values from 0 up to 200. The results apply to both low or high temperature conditions.

[Femtosecond time-resolved fluorescence spectra of LDS751]

The femtosecond time-resolved fluorescence depletion method has been introduced. In this method two beams of femtosecond laser was used. One excited the sample molecular to emit fluorescence. Then after specified time delay the second laser beam was introduced to deplete the fluorescence through the stimulate emission process. This method has been applied to LDS751 molecules in solution and its time-resolved fluorescence spectrum has been obtained.

Mutations in human ARF exon 2 disrupt its nucleolar localization and impair its ability to block nuclear export of MDM2 and p53

The mammalian ARF-INK4a locus uniquely encodes two cell cycle inhibitors by using separate promoters and alternative reading frames. p16INK4a maintains the retinoblastoma protein in its growth suppressive state while ARF stabilizes p53. We report that human ARF protein predominantly localizes to the nucleolus via a sequence within the exon 2-encoded C-terminal domain and is induced to leave the nucleolus by MDM2. ARF forms nuclear bodies with MDM2 and p53 and blocks p53 and MDM2 nuclear export. Tumor-associated mutations in ARF exon 2 disrupt ARF's nucleolus localization and reduce ARF's ability to block p53 nuclear export and to stabilize p53. Our results suggest an ARF-regulated MDM2-dependent p53 stabilization and link the human tumor-associated mutations in ARF with a functional alteration.

[Effect of puerarin on coronary collateral circulation in dogs with experimental acute myocardial infarction]

OBJECTIVE

To evaluate the effect and mechanism of puerarin on coronary collateral circulation in dogs with experimental acute myocardial infarction.

METHOD

Twelve dogs were randomly divided into puerarin (Gegen su, G) group and control(C) group, the acute myocardial infarction model was built in all dogs. Puerarin or saline was administered for 21 days. Coronary angiography was performed before and after ligating coronary artery. The capillaries and distribution vessel density in tissue sections of myocardium were assessed.

RESULT

Angiography on hour 2 and day 22 after ligating coronary artery revealed significant augmentation of collateral vessels in G group versus controls. Capillaries and distribution vessel density in ischemic and infarctive zone on day 22 revealed statistically significant augmentation in G group versus controls (P < 0.05 and P < 0.01).

CONCLUSION

Puerarin might improve the opening and forming of coronary collateral circulation to ischemic myocardium in dogs and protect ischemic myocardium.

ROC1, a homolog of APC11, represents a family of cullin partners with an associated ubiquitin ligase activity

We have identified two highly conserved RING finger proteins, ROC1 and ROC2, that are homologous to APC11, a subunit of the anaphase-promoting complex. ROC1 and ROC2 commonly interact with all cullins while APC11 specifically interacts with APC2, a cullin-related APC subunit. YeastROC1 encodes an essential gene whose reduced expression resulted in multiple, elongated buds and accumulation of Sic1p and Cln2p. ROC1 and APC11 immunocomplexes can catalyze isopeptide ligations to form polyubiquitin chains in an E1- and E2-dependent manner. ROC1 mutations completely abolished their ligase activity without noticeable changes in associated proteins. Ubiquitination of phosphorylated I kappa B alpha can be catalyzed by the ROC1 immunocomplex in vitro. Hence, combinations of ROC/APC11 and cullin proteins proteins potentially constitute a wide variety of ubiquitin ligases.

[Effect of decompression of blood vessel on vascular compressive tinnitus]

OBJECTIVE

To evaluate the diagnosis and surgical indications of vascular compressive tinnitus.

METHOD

We searched carefully the possible focus causing vascular compressive tinnitus around VIII cranial nerve in cerebellopontine angle via retrosigmoid sinus approach under microscope in 40 cases. The responsible blood vessels and synechia focus was separated and one piece of auto-musculomembrane was put between blood vessels and the nerve.

RESULT

We had 38 cases of operation. All of them had artery compression on the surface of VIII cranial nerve, 6 of them had arachnoid synechia. After operation, the symptoms of tinnitus disappeared thoroughly. Of them 4 cases with vertigo recovered also. Recurrences were found in 2 cases in the follow-up survey which last 6 monthes to 7 years and 2 monthes.

CONCLUSION

Surgical treatment of neurovascular decompression for vascular compressive tinnitus via retrosigmoid sinus approach has positive therapeutic effect as long as the diagnosis is correct.