Ferromagnetism in ZnO:Co originating from a hydrogenated Co-O-Co complex

The effects of hydrogen interstitials and oxygen vacancies on the overall ferromagnetic behaviour of Co doped ZnO (ZnO:Co) have been closely examined using different density functional calculations. The results demonstrate the importance of correcting the bandgap problem of the ZnO host as well as the lack of correlation in Co's 3d states which can severely affect the coupling of H and Co's impurity bands. Our results show that in hydrogenated ZnO:Co, hydrogen interstitial can also stabilize the ferromagnetic interaction at low Co concentrations, but this requires the formation of the in-plane O-H-Co-O-Co complex. In this structure, the hydrogen interstitial forms an anionic complex with the neighbouring oxygen, which polarizes the surrounding oxygen to mediate the ferromagnetism through the superexchange mechanism. An oxygen vacancy by itself would not cause ferromagnetism in ZnO:Co. On the other hand, in the presence of hydrogen interstitials, oxygen vacancies can significantly enhance the magnetic coupling between H and Co-O-Co as a shallow donor if it is far away from the in-plane O-H-Co-O-Co complex. However, the total energy results show that this is much more favoured when the oxygen vacancy is near the in-plane O-H-Co-O-Co complex, which can inhibit the ferromagnetic interaction between Co ions.

In silico study of Aquaporin V: Effects and affinity of the central pore-occluding lipid

Because of its roles in human physiology, Aquaporin V (AQP5), a major intrinsic protein, has been a subject of many in vitro studies. In particular, a 2008 experiment produced its crystal structure at 2.0Å resolution, which is in a tetrameric conformation consisting of four protomers. Each protomer forms an amphipathic pore that is fit for water permeation. The tetramer has a pore along its quasi-symmetry axis formed by quadruplets of hydrophobic residues (every protomer contributes equally to the quadruplets). A lipid, phosphatidylserine (PS6), is bound to AQP5 in the central pore, totally occluding it. A 2009 experiment showed that AQP5 facilitates not only permeation of water but also permeation of hydrophobic gas molecules across the cell membrane. In this article, we present an in silico study of AQP5 to elucidate the effects of PS6's binding to and dissociating from AQP5's central pore. Computing the lipid's chemical-potential along its dissociation path, we find that PS6 inhibits the function of the central pore with an IC(50) in the micromolar range. Examining the central pore and the interstices between two adjacent protomers, we propose that nonpolar gas molecules (O(2)) permeate through AQP5's hydrophobic central pore when un-occluded.

Solvothermal route to S-deficient CoS nanoplates and their cathodoluminescence and magnetic properties

A facile solvothermal method was developed to fabricate CoS nanoplates using ethylenediamine as solvent. The microstructure characterizations indicate that the CoS nanoplates have well-crystalline hexagonal phase and regular hexagonal or pentagonal shape. The XPS and ICP-AES measurements confirm the chemical composition of nanoplates is S-deficient CoS0.921. Cathodoluminescence spectra of both a large area of the nanoplates and individual nanoplate show broad emission bands centered at 615 nm. Magnetic measurements including magnetization dependence of temperature and magnetic hysteresis loops reveals that the CoS nanoplates exhibit room-temperature ferromagnetic behavior. It is found that intrinsic point defects mainly as V(s), Co(i) and/or the complex defects of V(s) and Co(i) should be responsible for both the broad emission band and the unique ferromagnetism.

Reliability of the Fukuda stepping test to determine the side of vestibular dysfunction

The Fukuda stepping test (FST) is widely used in neurology and for the diagnosis of vertigo-associated disease, but its reliability is disputed. This study assessed the accuracy of the FST in determining the side of vestibular dysfunction in 126 patients with unilateral vestibular lesion. Abnormal deviation towards the side of the lesion occurred in 50.0% of cases and towards the intact side in 24.6% of cases, with 25.4% of patients within the normal range (< 45° deviation). An equal percentage of patients with acute stage vertigo (0-3 days after onset) deviated towards the intact and lesion sides, however the percentage of patients deviating to the intact side decreased over time. A subset of patients who originally deviated towards the intact side gradually began to deviate towards the lesion side. Care should be taken when using the FST to determine the side of the lesion, particularly in acute stage vertigo.

EZH2 silencing by RNA interference inhibits proliferation in bladder cancer cell lines

The Enhancer of Zeste homologue2 gene (EZH2) is frequently expressed at high levels in malignant tumours, including bladder cancer. It functions as a transcriptional regulator to the maintenance of cell identity, cell cycle regulation and oncogenesis. In the study, we detected EZH2 expression in bladder cancer tissues. These results showed EZH2 high expression in bladder cancer tissue at level of transcript and protein compared with normal bladder tissue and EZH2 expression correlated positively with tumour stage and grade. Then, we used RNA interference to inhibit EZH2 expression in bladder cancer EJ cell line. Efficient downregulation of EZH2 resulted in significantly decreased cell proliferation in EJ cells and retarded transition of G(1) phase to S phase. Our data suggest that EZH2 is involved in the tumourigenesis of bladder cancer and EZH2 downregulation contributes to inhibiting malignant growth by retarding cell entrance to S phase.

Structure, stability and magnetism of cobalt doped (ZnO)n clusters

Clusters of magnetic impurities are believed to play an important role in retaining ferromagnetism in diluted magnetic semiconductors (DMS), the origin of which has been a long debated issue. Controlling the dopant homogeneity in magnetic semiconductors is therefore a critical issue for the fabrication of high performance DMS. The current paper presents a first principle study on the stability and magnetic properties of Co doped (ZnO)n (n = 12 and 15) clusters using density functional theory. The results show that cobalt ions in these clusters tend to increase their stabilities by maximizing their co-ordination numbers to oxygen. This will likely to be the case for (ZnO)n clusters with n other than 12 and 15 in order for Co to reside in a stable local crystal field. Expansive (shrinkage) stress is introduced when cobalt resides in exohedral substitutional (endohedral interstitial) sites; such strain can be offset by the cluster deformation. Bidoped cluster is found to be unstable due to the increase of system strain energy. All the doped clusters were found to preserve 3 microg of magnetic moments from Co in the overall clusters, but with part of the local moments on cobalt re-distributed onto neighboring oxygen atoms. Current findings may provide a better understanding on the structural chemistry of magnetic dopants in nanocrystallined DMS materials.

Structural and magnetic stability of dopants in ZnO-based dilute magnetic semiconductors

Structural and magnetic configurations of Co/Mn ions, the most widely studied transition metal dopants in ZnO-based dilute magnetic semiconductors, have been investigated using first-principles density functional calculations. The study provides a fundamental theoretical understanding on the distribution of the magnetic ions in the ZnO host and its corresponding magnetism. Results show that the substituent magnetic ions at the Zn site strongly tend to aggregate chain-like via oxygen on the ab plane with an antiferromagnetic coupling in contrast to paramagnetic isolated free Co/Mn. Substitutional Cu codoping is found theoretically to reduce the magnetic dopant's tendency towards chain-like aggregation, in good agreement with recent experimental observations.

The feeble role of oxygen vacancies in magnetic coupling in ZnO based dilute magnetic semiconductors

The role of the oxygen vacancy (V(O)) as the dominant defect in ZnO in magnetic interactions of ZnO based dilute magnetic semiconductors (DMSs) was examined in detail using density functional theory. It was found that V(O) does not lead to a thermally activated carrier mediated magnetism or form magnetic centers in the ZnO lattice. However, neutral V(O) may facilitate the ferromagnetism, but has a limited influence on the original antiferromagnetic coupling of the magnetic ions in oxygen stoichiometric ZnO DMSs. As a result, the ferromagnetism observed in previous experiments should be attributed to other defects such as hydrogen contamination or zinc interstitials.

Predominant role of defects in magnetic interactions in codoped ZnO:Co

The roles of codoping ions (Li, Ga and Cu) and defects (oxygen vacancy and hydrogen impurity) in magnetic interactions in ZnO:Co systems have been studied systematically using an ab initio method with density functional theory and the standard molecular field model. The results show that where defects are not included in ZnO's lattice carrier mediated magnetism is only achievable in shallow p-type codoping, such as ZnO:Co + Cu. However, in deep p-type codoping (ZnO:Co + Li) and deep n-type codoping (ZnO:Co + Ga), the carriers generally do not induce spontaneous magnetism. It was also found that the oxygen vacancy, due to its deep donor nature, has a minor favoring effect on ferromagnetic ordering among Co ions. The observed ferromagnetism in such systems can be attributed to the interaction of Co ions with unintentional hydrogen contamination rather than codopants or oxygen vacancies.

Hydrogen multicenter bond mediated magnetism in Co doped ZnO

Magnetism in Co doped ZnO (ZnO:Co) is strongly affected by the presence of the ZnO's extrinsic impurities, such as unintentional hydrogen dopants. Our ab initio investigation reveals that in ZnO:Co the formation of substitutional H (H(O)) with four-fold hydrogenic bonds is favored over interstitial hydrogen (H(I)) by 0.4 eV. It is found that H(O) is trapped by Co ions to form highly stable Co-H(O)-Co complexes. H(O) also mediates a strong short-ranged ferromagnetic interaction between Co dopants via short-range exchange interaction which induces room temperature ferromagnetism.

Substantial stabilization of ferromagnetism in ZnO:Mn induced by N codoping

Electronic structures and magnetic properties of ZnO:Mn and ZnO:Mn+N systems are investigated using first-principles density functional calculations with generalized gradient approximation. The results provide a fundamental theoretical understanding in the substantial ferromagnetic stability induced by N codoping in the ZnO:Mn system observed experimentally. They demonstrate that the ferromagnetic interaction is due to the hybridization between N 2p and Mn 3d states and is very sensitive to the geometrical configurations of dopants in the ZnO host lattice. The most stable ferromagnetic configuration corresponds to the Mn-N-Mn cluster, energetically strong enough to lead to hole-mediated ferromagnetism at room temperature.

A novel mechanism: Erxian Decoction, a Chinese medicine formula, for relieving menopausal syndrome

ETHNOPHARMACOLOGICAL RELEVANCE

Many clinical and experimental reports demonstrated that Erxian Decoction (EXD) was effective in relieving menopausal syndrome.

AIM OF THE STUDY

The mechanisms of action of EXD were explored on the endocrine and antioxidant regimen.

MATERIALS AND METHODS

Menopause causes a decline in both endocrine function and activities of antioxidant enzymes. In this study, 12-month-old female Sprague-Dawley-rats (SD-rats) with a low serum estradiol level were employed. Their endocrine functions after treatment with EXD were assessed by the determination of their serum estradiol level and ovarian mRNA levels of aromatase, which is a key enzyme for biosynthesis of estradiol. Meanwhile, superoxide dismutase-1 (SOD), catalase (CAT) and glutathione peroxidase (GPx-1) in the liver were also determined to assess the effect of EXD on the antioxidant regimen.

RESULTS

Results revealed a significant elevation in serum estradiol level and the mRNA level of ovarian aromatase and liver CAT in the EXD-treated menopausal rat model.

CONCLUSIONS

The results obtained from mRNA and estradiol level of the present investigation revealed that the EXD relieves the menopausal syndrome involved an increase of endocrine and antioxidant function through, at least, the activation of aromatase and CAT detoxifying pathways.

Isolation and aggregation of substituent Co in ZnO:Co diluted magnetic semiconductors

Distribution of magnetic ions in a semiconducting host is critical for the functionality of diluted magnetic semiconductors. By investigating the temperature- and field-dependent magnetization of single-phase polycrystalline ZnO:Co oxides, the substitution of Co at the Zn site is found not to occur randomly but Co ions appear to have a tendency for aggregation via oxygen with an antiferromagnetic coupling, in contrast to paramagnetic isolated free Co. The experimental findings are justified through first-principles density functional calculations based on the generalized gradient approximation. It suggests that Co dopants in ZnO:Co have a tendency towards staying close to each other along the ab plane.

A PstI polymorphism at 3'UTR of goat POU1F1 gene and its effect on cashmere production

POU1F1 is a positive regulator for prolactin (PRL) whose metabolites may directly or indirectly affect some aspects of the hair growth cycle, therefore, POU1F1 gene is an important candidate gene for cashmere traits selection through marker-assisted selection (MAS). Hence, in this study, the PCR-RFLP method was applied to detect a T>C transition determining a PstI polymorphism at the 3'UTR of POU1F1 locus and evaluate its associations with cashmere traits in 847 Inner Mongolia White Cashmere goats. In the analyzed population, the allelic frequencies for the T and C alleles are 0.959 and 0.041, respectively and the genotypic frequencies are in Hardy-Weinberg equilibrium (P > 0.05). Moreover, significant statistical relationships between the PstI polymorphism of POU1F1 gene and goat cashmere yields were found (*P < 0.05). When compared with TC genotype, TT genotype was associated with superior cashmere yields in 2, 4, and 5 years old individuals, as well as with average cashmere yield. Hence, TT genotype is suggested to be a molecular marker for senior cashmere yield.

Microwave assisted catalytic oxidation of p-nitrophenol in aqueous solution using carbon-supported copper catalyst

Carbon-supported copper (Cu/GAC) catalyst was prepared by conventional impregnation method and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The sizes of Cu particles dispersing on the surface of GAC were 0.3-1.5 microm, which could be penetrated by microwave so that Cu/GAC catalyst could absorb microwave energy effectively. The catalysis of Cu/GAC in microwave assisted catalytic oxidation of p-nitrophenol (PNP) in aqueous solution was investigated through a fixed bed reactor under ambient pressure and continuous flow mode. PNP removal reached 91.8% under optimized conditions, corresponding to 88% of TOC removal. It showed a higher PNP degradation and total organic carbon (TOC) removal for Cu/GAC catalyst than GAC alone, and Cu/GAC catalyst kept on a high catalysis and a good stability for a long time run, which indicated that GAC structure and catalytic capacity were improved by the load of Cu.

Fracture spacing in layered materials and pattern transition from parallel to polygonal fractures

We perform three-dimensional simulations of fracture growth in a three-layered plate model with an embedded heterogeneous layer under horizontal biaxial stretch (representing stretch from directional to isotropic) by the finite element approach. The fractures develop under a quasistatical, slowly increasing biaxial strain. The material inhomogeneities are accounted for by assigning each element a failure threshold that is defined by a given statistical distribution. A universal scale law of fracture spacing to biaxial strain in terms of principal stress ratio is well demonstrated in a three-dimensional fashion. The numerically obtained fracture patterns show a continuous pattern transition from parallel fractures, laddering fracture to polygonal fractures, which depends strongly on the far-field loading conditions in terms of principal stress ratio lambda = sigma(2)/sigma(1), from uniaxial (lambda = 0), anisotropic (0 < lambda < 1) to isotropic stretch (lambda = 1). We find that, except for further opening of existing fractures after they are well-developed (saturation), new fractures may also initiate and propagate along the interface between layers, which may serve as another mechanism to accommodate additional strain for fracture saturated layers.

Differential gene expression profiling in aggressive bladder transitional cell carcinoma compared to the adjacent microscopically normal urothelium by microdissection-SMART cDNA PCR-SSH

Identifying novel and known genes that are differentially expressed in aggressive bladder transitional cell carcinoma (BTCC) has important implications in understanding the biology of bladder tumorigenesis and developing new diagnostic and therapeutic agents. In this study we identified the differential gene expression profiles comparing tumor to the adjacent microscopically normal mucosa by manual microdissection on frozen sections. The RNAs extracted from microdissected tissues were amplified by SMART cDNA PCR technology to generate forward subtractive cDNA library by suppressive subtractive hybridization (SSH). We obtained 376 positive clones, one hundred clones of aggressive BTCC subtracted cDNA library were selected at random and inserts were reamplified by PCR. After differential screening by reverse dot blotting, 73 positive clones, that contend inserts putatively upregulated in aggressive BTCC, were further analysed by DNA sequencing, GenBank and EST database searching. Sequencing results showed that 66 clones stand for 23 known genes and 7 clones for three new EST (Genbank number: DN236875, DN236874 and DN236873). In conclusion, microdissection-SMART cDNA PCR-SSH allowed for an efficient way to identify aggressive BTCC-specific differential expressed genes that may potentially be involved in the carcinogenesis and/or progression of aggressive BTCC. These differentially expressed genes may be of potential utility as therapeutic and diagnostic targets for aggressive BTCC.

[Estimates of breeding value of Inner Mongolia cashmere goats using animal model BLUP method]

In this study, single trait animal model of best linear unbiased prediction (BLUP) procedures was used to obtain estimates of 3,981 Inner Mongolia cashmere goats' breeding value for body weight and cashmere yield. The data were collected during 1989-1998 at Arbas cashmere goats farm, Etuoke banner, Inner Mongolia. Multiple traits of BLUP were used to get estimates of total breeding values (TBV) of all goats. The model included age and sex-herd-year as fixed effects, and individual additive effect and individual permanent environment as random effects. The selection based on breeding value and phenotypic value was compared. The results showed as following: (1) There was a large difference between weaning weight selection and TBV selection of ram lamb; (2) The difference between phenotypic selection and TBV selection of gimmer hogg reached a significant level (P < 0.01); (3) The difference between phenotypic selection and TBV selection of ram hogg reached a significant level (P < 0.01); (4) Rank correlation between body weight selection and body weight' EBV selection and that between cashmere yield selection and cashmere yield' EBV selection were not significant (P > 0.05). The study concluded precision of individual phenotypic selection was low and animal model BLUP was suitable to select Inner Mongolia cashmere goats. At last, this study gave a series of methods of selecting sires based on objective reality.

Structure of the human serotonin 5-HT4 receptor gene and cloning of a novel 5-HT4 splice variant

Several variants of the serotonin 5-HT4 receptor are known to be produced by alternative splicing. To survey the existence and usage of exons in humans, we cloned the human 5-HT4 gene. Based on sequence analysis seven C-terminal variants (a-g) and one internal splice variant (h) were found. We concentrated in this study on the functional characterization of the novel splice variant h, which leads to the insertion of 14 amino acids into the second extracellular loop of the receptor. The h variant was cloned as a splice combination with the C-terminal b variant; therefore, we call this receptor 5-HT4(hb). This novel receptor variant was expressed transiently in COS-7 cells, and its pharmacological profile was compared with those of the previously cloned 5-HT4(a) and 5-HT4(b) isoforms, with the latter being the primary reference for the h variant. In competition binding experiments using reference 5-HT4 ligands, no significant differences were detected. However, the broadly used 5-HT4 antagonist GR113808 discriminated functionally among the receptor variants investigated. As expected, it was an antagonist on the 5-HT4(a) and 5-HT4(b) variant but showed partial agonistic activity on the 5-HT4(hb) variant. These data emphasize the importance of variations introduced by splicing for receptor pharmacology and may help in the understanding of conflicting results seen with 5-HT4 ligands in different model systems.

[Determination of aflatoxins in peanut by high performance liquid chromatography using immunoaffinity column clean-up and on-line electrochemical derivatization]

A method for the determination of aflatoxin B1, B2, G1 and G2 in peanut by high performance liquid chromatography using immunoaffinity column clean-up and on-line electrochemical derivatization was developed. Sample was extracted with 80% methanol and the extract was passed through the IAC. Aflatoxins were retained by the monoclonal in the IAC and eluted with actonitrile. AFT B1 and G1 were derivatized with on-line electrochemical equipment Kobra Cell. The four toxins can be separated in 13 minutes and the detection limit was 0.1 microgram/kg for each toxin. The method has been applied to the determination of peanut sample. The relative standard deviation was 9.2%-15% and the average recovery of AFT spiked at 0.5-9.0 micrograms/kg levels was in the range of 74.8%-97.3%.

Structural analysis of the mechanism of adenovirus binding to its human cellular receptor, CAR

Binding of virus particles to specific host cell surface receptors is known to be an obligatory step in infection even though the molecular basis for these interactions is not well characterized. The crystal structure of the adenovirus fiber knob domain in complex with domain I of its human cellular receptor, coxsackie and adenovirus receptor (CAR), is presented here. Surface-exposed loops on knob contact one face of CAR, forming a high-affinity complex. Topology mismatches between interacting surfaces create interfacial solvent-filled cavities and channels that may be targets for antiviral drug therapy. The structure identifies key determinants of binding specificity, which may suggest ways to modify the tropism of adenovirus-based gene therapy vectors.

Differentiation of medicinal Codonopsis species from adulterants by polymerase chain reaction-restriction fragment length polymorphism

DNA sequence analysis of rDNA internal transcribed spacer (ITS) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) were exploited for their applications in differentiating medicinal species Codonopsis pilosula, C. tangshen, C. modesta, and C. nervosa var. macrantha, from two related adulterants Campanumoea javania and Platycodon grandiflorus. The data demonstrated that the rDNA ITSI and ITSII sequences of the four Codonopsis are highly homologous but not identical, and are significantly different from those of the two adulterants. The sequence difference allows effective and reliable differentiation of Codonopsis from the adulterants by PCR-RFLP.

Random primed polymerase chain reaction differentiates Codonopsis pilosula from different localities

DNA fingerprints distinctive among the samples from different localities in China were successfully reproduced for the Chinese herb Dangshen, the roots of CODONOPSIS PILOSULA, (Campanulaceae). Similarity index (S.I.) analysis revealed that C. PILOSULA samples from the same province generated similar DNA fingerprints, while samples of different provinces displayed different DNA fingerprints. This method may be a general and valuable tool for locality authentication of other Chinese herbal medicinal materials.

Alteration of N-acetylglucosaminyltransferases in pancreatic carcinoma

The activities of three N-acetylglucosaminyltransferases (GnT III, GnT IV and GnT V) were determined in 10 samples of pancreatic carcinoma (PCa) and compared with those in 9 samples of normal pancreatic tissue (NP). It was found that the specific activities of GnT III, GnT IV and GnT V increased in all of the PCa samples. GnT III increased most significantly, up to 22.3 fold of normal, GnT IV was elevated 12.3 fold, while GnT V increased only 2.4 fold. The elevation of GnTs in pancreatic carcinoma was consistent with the increase in the number of antenna and bisecting GlcNAc structures in N-glycans of pancreatic ribonuclease (RNase) as assessed by Con A affinity chromatography. Polycytidylate specific RNase from the serum of PCa patients showed the same structural changes as that found in in N-glycans of the RNase from PCa tissue.

The cytochrome P-450 inhibitor cobalt chloride prevents inhibition of renal Na,K-ATPase and redistribution of apical NHE-3 during acute hypertension

Acute systolic arterial hypertension provokes a rapid decrease in proximal tubule sodium reabsorption and diuresis associated with inhibition of renal cortex Na,K-ATPase activity and redistribution of apical membrane Na/H exchanger (NHE-3) to heavier density membranes containing markers of intermicrovillar cleft and endosomes. Because cytochrome P-450-dependent arachidonate metabolites participate in the regulation of renal sodium transport and BP, this study tested the hypothesis that these renal responses to acute hypertension would be prevented if cytochrome P-450 metabolism were inhibited by cobalt chloride (CoCl2). Four groups of rats (n = 4 to 5) were studied: (1) sham-operated; (2) 50 mg of CoCl2/kg subcutaneously for 2 d; (3) acute hypertension by constricting arteries for 5 min; and (4) acute hypertension after CoCl2 treatment as in group 3. Renal cortex was analyzed after sorbitol density gradient fractionation. CoCl2 treatment alone did not significantly affect the rate of urine output, endogenous lithium clearance (an inverse measure of proximal tubule sodium reabsorption), maximal activity of Na,K-ATPase, or subcellular distribution of NHE-3-containing membranes. In non-CoCl2-treated animals, acute hypertension provoked a three- to fourfold increase in urine output and endogenous lithium clearance, 33% inhibition of renal cortex Na,K-ATPase activity, and redistribution of NHE-3 out of the apical membrane peak. In CoCl2-treated animals, acute urine output and endogenous lithium clearance increased only twofold during acute hypertension, there was no inhibition of Na,K-ATPase activity, and there was no redistribution of NHE-3 immunoreactivity to higher density membranes. These findings demonstrate that CoCl2 treatment both attenuates the inhibition of proximal tubule sodium reabsorption and diuresis and abolishes Na,K-ATPase inhibition and NHE-3 redistribution during acute hypertension, evidence that these responses may be mediated by cytochrome P-450 arachidonate metabolites.

Antiproliferation effects of hexadecylphosphocholine on solid tumour and leukaemia selectively in vitro

Hexadecylphosphocholine (HePC), an alkylphospholipid analogue representing a new class of antitumor agents, exerts sufficient oncolytic potencies that it might be developed as a selective antitumour drug. This paper reports that 12 cell lines of leukaemia and solid tumour employed in this study were inhibited by HePC in vitro. This result indicated that HePC possessed general antitumour properties, but did not interfere significantly with cell proliferation of normal BMC in tests of colony formation in granulocytic-macrophage colonies (CFU-GM). Because of these advantages, we suggest that HePC would be an excellent antitumour agent for selectively killing tumour cells and is of low toxicity as compared to conventional cytotoxic agents.

The VRG4 gene is required for GDP-mannose transport into the lumen of the Golgi in the yeast, Saccharomyces cerevisiae

In the yeast Saccharomyces cerevisiae, glycoproteins and sphingolipids are modified in the Golgi by the addition of mannose residues. The critical mannosyl donor for these reactions is the nucleotide sugar, GDP-mannose, whose transport into the Golgi from the cytoplasm is required for mannosylation. This transport reaction has been well characterized, but the nucleotide sugar transporter has yet to be identified in yeast. VRG4 is an essential gene whose product is required for a number of Golgi-specific functions, including glycosylation and the organization of the endomembrane system. Here, data are presented that demonstrate that the primary role of Vrg4p is in the transport of GDP-mannose into the Golgi. The vrg4 mutation causes a general impairment in mannosylation, affecting N-linked and O-linked glycoprotein modifications as well as the mannosylation of sphingolipids. By using an in vitro assay, vrg4 mutants were shown to be specifically defective in the transport of GDP-mannose into Golgi vesicles. The Vrg4 protein localizes to the Golgi complex in a pattern that suggests a wide distribution throughout the Golgi. Vrg4p displays homology to other putative nucleotide sugar transporters, suggesting that the VRG4 gene encodes a Golgi GDP-mannose transporter. As Vrg4p is essential, these results suggest that a complete lack of mannosylation of glycoproteins in the Golgi leads to inviability. Alternatively, the essential function of Vrg4p in yeast involves its effect on sphingolipids, which would imply a critical role for mannosylinositol phosphorylceramides or mannosyl diphosphoinositol ceramides on growth and viability.

Analysis of a Streptococcus pneumoniae gene encoding signal peptidase I and overproduction of the enzyme

The spi gene of Streptococcus pneumoniae was cloned and its nucleotide sequence was determined. It encodes a protein of 204 amino acids that is homologous to bacterial signal peptidase I proteins. The S. pneumoniae protein contains all of the conserved amino acid sequence motifs previously identified in this enzyme from both prokaryotic and eukaryotic sources. Sequence comparisons revealed several additional motifs characteristic of the enzyme. The cloned S. pneumoniae gene complemented an Escherichia coli mutant defective in its leader peptidase gene. Expression of the spi gene in S. pneumoniae appeared to be essential for viability. The cloned gene was shown to produce a polypeptide of approximately 20 kDa. Overproduction of the S. pneumoniae spi gene in an E. coli expression system gave a native protein product, soluble in the presence of a non-ionic detergent, which should be amenable to structural determination.

The rnhB gene encoding RNase HII of Streptococcus pneumoniae and evidence of conserved motifs in eucaryotic genes

A single RNase H enzyme was detected in extracts of Streptococcus pneumoniae. The gene encoding this enzyme was cloned and expressed in Escherichia coli, as demonstrated by its ability to complement a double-mutant rnhA recC strain. Sequence analysis of the cloned DNA revealed an open reading frame of 290 codons that encodes a polypeptide of 31.9 kDa. The predicted protein exhibits a low level of homology (19% identity of amino acid residues) to RNase HII encoded by rnhB of E. coli. Identification of the S. pneumoniae RNase HII translation start site by amino-terminal sequencing of the protein and of mRNA start sites by primer extension with reverse transcriptase showed that the major transcript encoding rnhB begins at the protein start site. Comparison of the S. pneumoniae and E. coli RNase HII sequences and sequences of other, putative bacterial rnhB gene products surmised from sequencing data revealed three conserved motifs. Use of these motifs to search for homologous genes in eucaryotes demonstrated the presence of rnhB genes in a yeast and a roundworm. Partial rnhB gene sequences were detected among expressed sequences of mouse and human cells. From these data, it appears that RNase HII is universally present in living cells.

The usefulness of technetium-99m-MIBI scintimammography in diagnosis of breast cancer: using surgical histopathologic diagnosis as the gold standard

The purpose of this study was to evaluate the usefulness of 99mTc-MIBI scintinammography for the detection of breast cancer.

METHODS

Sixty-one consecutive patients referred for a suspicions breast lesion on clinical examination were studied with 99mTc-MIBI scintimammography. There were 60 female patients and 1 male patient with 63 pulpable breast abnormalities. Each patient received 20mCi 99mTc-MIBI intravenously. Ten and 120 minutes postinjection, three planar views, right and left lateral prone and anterior supine thoracic views, were obtained. The patient underwent surgery within one week and the final diagnostic results (histopathology) were obtained.

RESULTS

Thirty-two of 63 abnormalities of breast were pathologically confirmed breast cancer, and 31 were benign lesions. In the group of patients studied, the sensitivity of 99mTc-MIBI scintimammography was 78.1% (25 true-positive, 7 false-negative) and the specificity was 90.3% (28 true-negative, 3 false positive). The positive predictive value was 89.3%, the negative predictive value was 80.0%, the positive likelihood ratio was 8.1, the negative likelihood ratio was 0.2.

CONCLUSION

This study showed the high diagnostic accuracy of 99mTc-MIBI scintimammography in detecting breast cancer. 99mTc-MIBI scintimammography can be used as an assistant method to non-invasively assess breast cancer invasiveness before surgery.

Reduction of myocardial ischemia-reperfusion injury by isovolumic hemodilution

In order to study the effects of isovolumic hemodilution and its combination with Danshen solution on acute ischemic reperfused canine myocardium, 24 adult hybrid dogs were used and divided into four groups. Group I was the control group, groups II-IV were treated with Dextron 40, Danshen solution and a combination of the two, respectively. The results showed that either Dextron 40 or Danshen solution alone had a significant increase of +/- dp/dt-max when compared with group I (p < 0.05). Although no significant difference existed between group II and III, the former showed more rapid action. The combination of the two therapies improved +/- dp/dt-max and LVSP, and significantly reduced the necrotic sizes and the MDA contents in the ischemic myocardia compared with not only group I, but also group II or group III (all p < 0.05). The results suggest that isovolumic hemodilution or Danshen may protect the ischemic reperfused myocardium and the former may come into action more rapidly, and that the combination of the two may show a better synergism than each one of the two by itself.

Elevation of cytosolic calcium of rat cardiac myocytes in phosphate depletion

Phosphate depletion is associated with a rise in cytosolic calcium ([Ca2+]i) of cells and such a derangement is responsible in major part for organ dysfunction in phosphate depletion (PD). Cardiac function is impaired in PD, and it is possible that PD is also associated with rise in [Ca2+]i of cardiac myocytes. The present study examined the effect of PD on [Ca2+]i of cardiac myocytes and explored the mechanisms that may lead to the rise in their [Ca2+]i. The [Ca2+]i of cardiac myocytes began to rise and ATP content began to fall at the third week of PD. After six weeks of PD, the values of [Ca2+]i were significantly higher (P < 0.01) and those of ATP content were significantly lower (P < 0.01) than in control (PW) rats. The Vmax of Ca2(+)-ATPase and Na+,K(+)-ATPase as well as the Na(+)-Ca2+ exchange were significantly lower (P < 0.01) in PD than in PW animals. The data of the present study are consistent with the notion that the rise in [Ca2+]i of cardiac myocytes of PD rats is due to a decrease in calcium efflux out of them.

[Active constituents of Commelina communis L]

According to the pharmacological results five compounds were isolated from the herb of Commelina communis. Based on physico-chemical constants and spectral data, four of them were identified as n-triacontanol, p-hydroxycinnamic acid, daucosteril and D-mannitol. p-hydroxycinnamic acid shows antibacterial activity and D-mannitol shows antitussive effect.

Altered cytosolic calcium homeostasis in rat cardiac myocytes in CRF

Chronic renal failure (CRF) is associated with an increase in calcium content of heart. This was attributed to the secondary hyperparathyroidism of CRF, since PTH augments entry of calcium into cardiac myocytes. At present, it is not known whether the increase in calcium content of heart reflects a rise in basal levels of cytosolic calcium ([Ca2+]) of cardiac myocytes. Further, in order for the PTH-induced entry of calcium into cardiac myocytes to raise their basal levels of [Ca2+]i, calcium extrusion out of these cells should be impaired as well. The present study examined the effect of CRF with and without excess PTH (PTX) and of the treatment of CRF rats with verapamil on basal levels of [Ca2+]i and ATP content of cardiac myocytes and on the activities of the pumps that are directly (Ca(2+)-ATPase and Na(+)-Ca2+ exchanger) and indirectly (Na(+)-K+ ATPase) responsible for calcium extrusion out of these cells. The basal levels of [Ca2+]i of cardiac myocytes increased (P < 0.01) and their ATP content decreased (P < 0.01) as the duration of CRF advanced. CRF was associated with significant decrement in Vmax of Ca2+ ATPase and Na(+)-K+ ATPase and in Na(+)-Ca2+ exchange. These derangements were prevented by prior PTX of the CRF rats or by their treatment with verapamil.(ABSTRACT TRUNCATED AT 250 WORDS)

Parathyroid hormone increases cytosolic calcium concentration in adult rat cardiac myocytes

The heart is a target organ for parathyroid hormone (PTH), and the action of this hormone on the myocardium may be mediated through the ability of PTH to increase cytosolic calcium ([Ca2+]i) in the myocardial cells. However, direct evidence for such an effect of PTH is lacking, and the mechanism(s) through which the hormone can potentially exert such an effect have not been elucidated. In the present study these questions were examined using cardiac myocytes isolated from adult rats. Both PTH-(1-34) and PTH-(1-84) produced a dose-dependent increase in [Ca2+]i of myocytes, but the effect of the latter was significantly (P < 0.01) greater than the former. This action of PTH was abolished by the inactivation of the hormone, the use of a PTH antagonist, or by verapamil. The G protein activator, guanosine 5'-O-(3-thiothriphosphate) (GTP gamma S), mimicked the effect of PTH, whereas pertussis toxin, the G protein inhibitor, guanosine 5'-O-(2-thiodiphosphate) (GDP beta S), or ryanodine significantly reduced the PTH-induced rise in [Ca2+]i. Dibutyryl- and 8-bromoadenosine-3',5'-cyclic monophosphate, forskolin, 12-O-tetradecanoylphorbol 13-acetate, and staurosporine did not increase [Ca2+]i in myocytes, and staurosporine did not alter the PTH-induced rise in [Ca2+]i. BAY K 8644 augmented the effect of PTH on [Ca2+]i. These data demonstrate that 1) PTH increases [Ca2+]i of cardiac myocytes, 2) this action is receptor mediated and is produced by activation of the L-type calcium channels following stimulation of G protein(s), and 3) the rise in [Ca2+]i is due to both augmented entry of calcium into the myocytes and mobilization of calcium from sarcoplasmic reticulum by a calcium-induced calcium release mechanism.

Survival of implanted fetal dopamine cells and neurologic improvement 12 to 46 months after transplantation for Parkinson's disease

BACKGROUND AND METHODS

Patients with Parkinson's disease tend to have a reduced response to levodopa after 5 to 20 years of therapy, with "on-off" fluctuations consisting of dyskinesia alternating with immobility. In an effort to modify the motor disability of advanced Parkinson's disease, we implanted embryonic mesencephalic tissue containing dopamine cells into the caudate and putamen of seven patients. Two patients received unilateral grafts in the caudate and the putamen on the side opposite the side with worse symptoms. Five patients received bilateral grafts implanted in the putamen only. In six of the seven patients, the fetal tissue was obtained from a single embryo with a gestational age of seven to eight weeks. The tissue was injected by means of 10 to 14 needle passes. There were no surgical complications. Four of the seven patients underwent immunosuppression with cyclosporine and prednisone.

RESULTS

All patients reported improvement according to the Activities of Daily Living Scale when in the on state 3 to 12 months after surgery (P < 0.01). Neurologic examination according to the Unified Disease Rating Scale showed that five of the seven patients improved when in the on state six months after surgery. The mean group Hoehn-Yahr score improved from 3.71 to 2.50 (P < 0.01). Computer and videotape testing in the home supported these findings. Fluctuations in clinical state were moderated, and periods of dyskinesia and off episodes were shorter and less severe than before implantation. Drug doses were reduced by an average of 39 percent (P < 0.01; maximum, 58 percent). The results of clinical evaluation and fluorodopa positron-emission tomography in one patient were compatible with transplant survival for as long as 46 months. Both immunosuppressed and nonimmunosuppressed patients improved.

CONCLUSIONS

Fetal-tissue implants appear to offer long-term clinical benefit to some patients with advanced Parkinson's disease.

Correct insertion of a simple eukaryotic plasma-membrane protein into the cytoplasmic membrane of Escherichia coli

A genetic system for directly synthesizing eukaryotic membrane proteins in Escherichia coli and assessing their ability to insert into the bacterial cytoplasmic membrane is described. The components of this system are the direct expression vector, pYZ4, and the mature beta-lactamase (BlaM) cassette plasmid, pYZ5, that can be used to generate translational fusions of BlaM to any synthesized membrane protein. The beta-subunit of sheep-kidney Na,K-ATPase (beta NKA), a class-II plasma membrane protein, was synthesized in E. coli using pYZ4, and BlaM was fused to a normally extracellular portion of it. The fusion protein conferred ampicillin resistance on individual host cells, indicating that the BlaM portion had been translocated to the bacterial periplasm, and that, by inference, the eukaryotic plasma-membrane protein can insert into the bacterial cytoplasmic membrane. A series of 31 beta NKA::BlaM fusion proteins was isolated and characterised to map the topology of the eukaryotic plasma membrane protein with respect to the bacterial cytoplasmic membrane. This analysis revealed that the organisation of the beta NKA in the E. coli cytoplasmic membrane was indistinguishable from that in its native plasma membrane.

[Electron microscopic observations on Bacteroides thetaiotaomicron]

Three strains of B. thetaiotaomicron have been isolated from caeca of BALB/c-nu/+ mice of SPF. These Bacteroides are obligately anaerobic, Gram-negative, non-spore-forming and non-motil without flagella rods. A characteristic of staining is deep at ends and stainless at the medium of a rod. The isolation and identification of these strains has been reported in 1987. This paper introduced only the results of EM observations. Under the SEM, the unstained area of rods is always showing a concavity, which is just a nucleoid in sections under the TEM. Many lamellar corpuscles have been found in cell plasma. Some of them have been secreted out of the cells. The chemical properties and physiological functions of them are unknown.