Spica Prunellae extract inhibits the proliferation of human colon carcinoma cells via the regulation of the cell cycle

Spica Prunellae has long been used as a significant component in numerous traditional Chinese medicine (TCM) formulas to clinically treat cancers. Previously, Spica Prunellae was shown to promote cancer cell apoptosis and inhibit angiogenesis in vivo and in vitro. To further elucidate the precise mechanism of its tumoricidal activity, the effect of the ethanol extract of Spica Prunellae (EESP) on the proliferation of human colon carcinoma HT-29 cells was elucidated and the underlying molecular mechanisms were investigated. The proliferation of HT-29 cells was evaluated using 3-(4, 5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation analyses. The cell cycle was determined using fluorescence-activated cell sorting (FACS) with propidium iodide (PI) staining. The mRNA and protein expression of cyclin-dependent kinase 4 (CDK4) and cyclin D1 was examined using RT-PCR and western blotting, respectively. EESP was observed to inhibit HT-29 viability and survival in a dose- and time-dependent manner. Furthermore, EESP treatment blocked G₁/S cell cycle progression and reduced the expression of pro-proliferative cyclin D1 and CDK4 at the transcriptional and translational levels. Altogether, these data suggest that the inhibition of cell proliferation via G₁/S cell cycle arrest may be one of the mechanisms through which Spica Prunellae treats cancer.

Patrinia scabiosaefolia inhibits colorectal cancer growth through suppression of tumor angiogenesis

Angiogenesis is an essential process for tumor development and metastasis, therefore inhibition of tumor angiogenesis has become a promising strategy for anticancer treatments. Patrinia scabiosaefolia, a well-known Oriental folk medicine, has been shown to be effective in the clinical treatment of gastrointestinal cancers. However, the precise mechanism of its tumoricidal activity remains largely unknown. Using a colorectal cancer (CRC) mouse xenograft model, the human colon carcinoma cell line HT-29 and human umbilical vein endothelial cells (HUVECs), in the present study we evaluated the effects of an ethanol extract of Patrinia scabiosaefolia (EEPS) on tumor angiogenesis in vivo and in vitro, and investigated the underlying molecular mechanisms. We found that EEPS treatment significantly reduced the tumor volume in CRC mice and decreased the intratumoral microvessel density in tumor tissues. In addition, EEPS inhibited several key processes of angiogenesis, including the proliferation, migration and tube formation of HUVECs. Moreover, EEPS treatment suppressed the expression of VEGF-A in CRC tumors and HT-29 cells. Collectively, our data suggest that Patrinia scabiosaefolia inhibits CRC growth likely via suppression of tumor angiogenesis.

Pien Tze Huang suppresses IL-6-inducible STAT3 activation in human colon carcinoma cells through induction of SOCS3

IL-6/STAT3 is one of the most critical cellular signal transduction pathways known to malfunction in colorectal cancer (CRC). As a target gene of signal transducer and activator of transcription 3 (STAT3) signaling, suppressor of cytokine signaling 3 (SOCS3) can be quickly induced by interleukin-6 (IL-6) stimulation but it then strongly inhibits IL-6-mediated STAT3 activation, functioning as a negative feedback regulator of the IL-6/STAT3 pathway. Aberrant activation of STAT3 and/or reduced expression of SOCS are strongly correlated with carcinogenesis, which therefore becomes a promising target for the development of novel anticancer chemotherapies. Pien Tze Huang (PZH) is a well-known traditional Chinese formula that was first prescribed by a royal physician 450 years ago in the Ming Dynasty. It has been used in China and Southeast Asia for centuries as a folk remedy for various types of cancer including CRC. However, the precise mechanism of its antitumor activity remains largely unclear. In the present study, we found that PZH could significantly and dose-dependently inhibit IL-6-mediated increase of STAT3 phosphorylation levels and transcriptional activity in the human colon carcinoma HT-29 cells, resulting in the suppression of cell proliferation and the induction of apoptosis. In addition, PZH treatment profoundly inhibited IL-6-induced upregulation of cyclin D1 and Bcl-2, two key target genes of the STAT3 pathway. Moreover, PZH treatment increased the expression of SOCS3. These results suggest that PZH could effectively inhibit proliferation and promote apoptosis of human colon carcinoma cells via modulation of the IL-6/STAT3 signaling pathway and its target genes.

Pien Tze Huang inhibits the proliferation of human colon carcinoma cells by arresting G1/S cell cycle progression

Pien Tze Huang (PZH), a well-known traditional Chinese formula prescribed 450 years ago in the Ming Dynasty, has been used in China and Southeast Asia for centuries as a folk remedy for various types of cancer, including colorectal cancer (CRC). Recently, we reported that PZH is capable of inhibiting colon cancer growth both in vivo and in vitro via the promotion of apoptosis and inhibition of tumor angiogenesis. To elucidate the mechanism of the tumoricidal activity of PZH, its effect on the proliferation of human colon carcinoma Caco-2 cells was evaluated and the underlying molecular mechanism was investigated. Results showed that PZH inhibited Caco-2 cell viability and survival in a dose- and/or time-dependent manner. In addition, PZH treatment was found to block the G1/S cell cycle progression. Moreover, PZH suppressed the mRNA and protein expression of pro-proliferative Cyclin D1 and CDK4. Findings of the present study suggest that inhibition of cell proliferation via the G1/S cell cycle arrest is a potential mechanism by which PZH can be effective in the treatment of cancer.

A spiking neuron circuit based on a carbon nanotube transistor

A spiking neuron circuit based on a carbon nanotube (CNT) transistor is presented in this paper. The spiking neuron circuit has a crossbar architecture in which the transistor gates are connected to its row electrodes and the transistor sources are connected to its column electrodes. An electrochemical cell is incorporated in the gate of the transistor by sandwiching a hydrogen-doped poly(ethylene glycol)methyl ether (PEG) electrolyte between the CNT channel and the top gate electrode. An input spike applied to the gate triggers a dynamic drift of the hydrogen ions in the PEG electrolyte, resulting in a post-synaptic current (PSC) through the CNT channel. Spikes input into the rows trigger PSCs through multiple CNT transistors, and PSCs cumulate in the columns and integrate into a 'soma' circuit to trigger output spikes based on an integrate-and-fire mechanism. The spiking neuron circuit can potentially emulate biological neuron networks and their intelligent functions.

CCL2−2518 (A/G) polymorphisms and tuberculosis susceptibility: a meta-analysis

BACKGROUND

It has been found that the -2518 C-C motif ligand (CCL)-2 promoter variant increases the risk of developing active tuberculosis (TB).

OBJECTIVE

To study the association between -2518 variants and susceptibility to TB.

DESIGN

We searched Medline, PubMed and the Wan Fang databases for human genetic studies on whether the -2518 CCL2 polymorphism influences the expression of active TB. Articles published from January 1998 to November 2010 were included. A random effects model was conducted in the meta-analysis.

RESULTS

The CCL2-2518G allele (OR 1.51, 95%CI 1.11-2.04, P = 0.008) showed significant association with susceptibility to TB. In genotype analysis, the recessive model (CCL2 genotype GG, OR 1.66, 95%CI 1.19-2.33, P = 0.003) was slightly superior to the dominant model (G carrier genotypes OR 1.53, 95%CI 1.07-2.17, P = 0.018). These observations were prominent among Asians and Latin-Americans of Hispanic ancestry, but not in Africans from Ghana and South Africa. The presence of epistatic genes in one population but not in the other, environmental differences and pathogen virulence may account for this.

CONCLUSION

The CCL2-2518G allele increases the risk of developing TB in Asians and Hispanics.

Hedyotis diffusa Willd inhibits colorectal cancer growth in vivo via inhibition of STAT3 signaling pathway

Signal Transducer and Activator of Transcription 3 (STAT3), a common oncogenic mediator, is constitutively activated in many types of human cancers; therefore it is a major focus in the development of novel anti-cancer agents. Hedyotis diffusa Willd has been used as a major component in several Chinese medicine formulas for the clinical treatment of colorectal cancer (CRC). However, the precise mechanism of its anti-tumor activity remains largely unclear. Using a CRC mouse xenograft model, in the present study we evaluated the effect of the ethanol extract of Hedyotis diffusa Willd (EEHDW) on tumor growth in vivo and investigated the underlying molecular mechanisms. We found that EEHDW reduced tumor volume and tumor weight, but had no effect on body weight gain in CRC mice, demonstrating that EEHDW can inhibit CRC growth in vivo without apparent adverse effect. In addition, EEHDW treatment suppressed STAT3 phosphorylation in tumor tissues, which in turn resulted in the promotion of cancer cell apoptosis and inhibition of proliferation. Moreover, EEHDW treatment altered the expression pattern of several important target genes of the STAT3 signaling pathway, i.e., decreased expression of Cyclin D1, CDK4 and Bcl-2 as well as up-regulated p21 and Bax. These results suggest that suppression of the STAT3 pathway might be one of the mechanisms by which EEHDW treats colorectal cancer.

Comparative safety of antiepileptic drugs during pregnancy

OBJECTIVE

To assess the safety of the newer antiepileptic drugs (AEDs) during pregnancy.

METHODS

The study population was pregnant women who enrolled in the North American AED Pregnancy Registry between 1997 and 2011. Data on AED use and maternal characteristics were collected through phone interviews at enrollment, at 7 months' gestation, and postpartum. Malformations were confirmed by medical records. The risk of major malformations was calculated among infants exposed to specific AEDs in monotherapy during the first trimester of pregnancy and among an unexposed group. Risk ratios (RRs) and 95% confidence intervals (CIs) were estimated with logistic regression.

RESULTS

The risk of major malformations was 9.3% (30 of 323) for valproate, 5.5% (11 of 199) for phenobarbital, 4.2% (15 of 359) for topiramate, 3.0% (31 of 1.033) for carbamazepine, 2.9% (12 of 416) for phenytoin, 2.4% (11 of 450) for levetiracetam, and 2.0% (31 of 1,562) for lamotrigine. Compared with lamotrigine, the RR was 5.1 (95% CI 3.0-8.5) for valproate, 2.9 (1.4-5.8) for phenobarbital, and 2.2 (1.2-4.0) for topiramate. The proportion of women with epilepsy who had seizures during pregnancy ranged from 23% for valproate to 31% for lamotrigine. Valproate was associated with a higher risk of neural tube defects, hypospadias, cardiac defects, and oral clefts and phenobarbital with a higher risk of cardiac defects and oral clefts; 5 infants exposed to topiramate (1.4%) had a cleft lip.

CONCLUSIONS

AEDs such as valproate and phenobarbital were associated with a higher risk of major malformations than newer AEDs such as lamotrigine and levetiracetam. Topiramate was associated with an increased risk of cleft lip compared with that of a reference population.

Effects of various salinities on Na(+)-K(+)-ATPase, Hsp70 and Hsp90 expression profiles in juvenile mitten crabs, Eriocheir sinensis

Eriocheir sinensis is a euryhaline crab migrating from sea to freshwater habitats during the juvenile stage. We used quantitative real-time polymerase chain reaction (qRT-PCR) to investigate the gene expression profile of Na(+)-K(+)-ATPase, Hsp70 (heat shock protein 70) and Hsp90 in megalopa exposed to salinities of 0, 2, 5, 10, and 15 parts per thousand. Both low and high salinities markedly stimulated expression of Na(+)-K(+)-ATPase, Hsp70 and Hsp90 genes of Chinese mitten crab megalopa; salinity had different effects on Na(+)-K(+)-ATPase, Hsp70 and Hsp90 levels depending on the duration of salinity stress, implying that Na(+)-K(+)-ATPase, Hsp70 and Hsp90 may play an important role in salinity tolerance in this crab species.

Pien Tze Huang inhibits tumor cell proliferation and promotes apoptosis via suppressing the STAT3 pathway in a colorectal cancer mouse model

Signal transducer and activator of transcription 3 (STAT3) plays a critical role in cell survival and proliferation. Constitutive activation of STAT3 is strongly correlated with pathogenesis of various types of malignant tumors including colorectal cancer (CRC), and therefore is a major focus in the development of anti-cancer agents. Pien Tze Huang (PZH), a well-known traditional Chinese formula prescribed already in the Ming Dynasty, has been demonstrated to be clinically effective in the treatment of CRC. However, the precise mechanism of its anti-cancer activity remains largely unknown. In the present study we evaluated the efficacy of PZH against tumor growth in vivo in the CRC mouse xenograft model, and investigated the underlying molecular mechanisms. We found that administration of PZH reduced tumor volume and tumor weight but had no effect on body weight gain in CRC mice, demonstrating that PZH can inhibit colon cancer growth in vivo without apparent adverse effect. We also observed that PZH treatment inhibited the phosphorylation level of STAT3 in tumor tissues. Consequently, the inhibitory effect of PZH on STAT3 activation resulted in the up-regulation of Bax/Bcl-2 ratio as well as down-regulation of Cyclin D1 and CDK4 expression, leading to the induction of apoptosis as well as the inhibition of cell proliferation. These results suggest that promotion of cancer cell apoptosis and inhibition of proliferation via suppression of STAT3 pathway might be one of the mechanisms by which PZH treats colorectal cancer.

Treatment limitations imposed by antiretroviral drug resistance mutations: implication for choices of first line regimens in resource-limited settings

BACKGROUND

Recent studies have suggested that failing nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimens may have greater potential to induce the development of resistance mutations, which may limit options for second-line therapy.

METHODS

Antiretroviral therapy (ART)-naïve individuals aged ≥18 years who initiated triple combination ART between January 2000 and June 2006 in British Columbia, Canada were enrolled in the study. We compared genotypic sensitivity scores (GSSs) derived from the development of resistance mutations between participants who initiated ART with ritonavir-boosted protease inhibitors (PIs) with those who initiated ART with NNRTIs, and determined the effects of these mutations on remaining active drugs.

RESULTS

A total of 1666 participants initiated ART, 818 (49.1%) with NNRTI-based regimens and 848 (50.9%) with boosted PI-based regimens. Among participants who developed resistance mutations, those who initiated NNRTI-based regimens had a lower median GSS than those on boosted PI-based regimens (9.8 vs. 11.0, respectively; P<0.001). Participants on boosted PI-based regimens [adjusted odds ratio (AOR) 3.68; 95% confidence interval (CI) 2.25, 6.01], those with ≥95% adherence to highly active antiretroviral therapy (HAART) (AOR 1.84; 95% CI 1.16, 2.92) and those with baseline CD4 count >200 cells/μL (AOR 3.44; 95% CI 1.73, 6.84) were more likely to have the maximum number of drug options.

CONCLUSION

The use of NNRTI-based first-line ART regimens may limit the options for second-line treatment when the number of available drugs is limited.

Single step measurement of optical transmitters Henry factor using sinusoidal optical phase modulations

Measurement of the Henry factor over large optical bandwidth is carried out in a single step without any filtering, using a technique based on the sinusoidal phase modulation method. This fast technique was successfully applied to a directly modulated Fabry Perot laser to obtain simultaneously the linewidth enhancement factor (LEF) of 14 longitudinal modes. It is also well suited for electro-absorption modulators (EAM) for which the α-factor is determined over 15 nm optical bandwidth. A very good agreement is found with the well established fiber transfer function method.

The role of p27(Kip1) phosphorylation at serine 10 in the migration of malignant glioma cells in vitro

Until recently, Cip/Kip members were almost solely viewed as nuclear proteins with a principal function of inhibiting cyclin/cyclin dependent kinase (CDK) activity and hence, inhibiting cell cycle progression. P27(Kip1) (hereafter p27) belongs to the Cip/Kip family that binds and inhibits all the cyclin/CDK complexes, thus often referred as a universal CDK inhibitor. However, emerging studies now suggest that Cip/Kip proteins play additional roles outside of the nucleus. Indeed, previous reports have linked p27 to the regulation of actin dynamics and cell migration. In this study, we constructed a model of migration-activated glioma cells by using the migration-stimulating substrate, a kind of ECM, laminin in vitro. Our results present evidence that laminin drives glioma cell migration without altering cell proliferation. Further, actively migrating cells which expressioned high phosphorylation of p27 at Ser10, and induced its cytoplasmic localization. In this process, Jab1 and CRM1 were also involved. Thus phosphorylation of p27 at Ser10 is necessary for both cytoplasmic localization and induction of cell migration. These observations solidified a genetic role of p27 in cell migration and this was independent of cyclin/CDK inhibition. Eventually, we transiently transfected p27S10A into T98G glioma cells, found that overexpression of p27S10A inhibited cell migration but not cell proliferation. These data linked phosphorylation of p27 at Ser10 and cell motility. Therefore, the major phosphorylation site at Ser10 of p27 played a pivotal role in the migration of malignant glioma cells.

A phase I study of XL281, a selective oral RAF kinase inhibitor, in patients (Pts) with advanced solid tumors

3513

Background: XL281 is a potent and selective inhibitor of wild type and mutant RAF kinases showing anti-tumor activity in multiple xenograft models. Mutations in KRAS or BRAF can activate the RAF/MEK/ERK pathway in human tumors and may promote sensitivity to RAF kinase inhibitors. Methods: Pts were enrolled in successive cohorts of XL281 orally once daily on a 28-day cycle. Tumor response was assessed per RECIST every 8 wks. Plasma pharmacokinetic and pharmacodynamic samples were collected. The maximum tolerated dose (MTD) was expanded to 10 pts each with colorectal (CRC), melanoma, papillary thyroid (PTC) and NSCLC. Pre- and post-dose tumor and surrogate tissues were obtained. Biomarker and genotype analyses of pathway genes were performed. Results: The dose escalation phase is complete; 30 pts were treated with XL281. DLTs of fatigue, nausea, vomiting, and diarrhea were observed at the MAD (225 mg). The MTD is 150 mg. The most common related AEs included Grade 1/2, fatigue (48%), diarrhea (35%), nausea (35%), vomiting (35%) and anorexia (30%). Three pts had related AEs ≥G3: hypokalemia, nausea, and vomiting. One pt with an ocular melanoma demonstrated a cPR of 4 mos duration. Twelve pts had SD (3 -17+ mos), including 2 with I131-refractory PTC harboring BRAF V600E mutations (15+ and 17+ mos). Nine of these pts had decreases in target lesions (5–29%), including a pt with KRAS mutant CRC on study for 20 wks with marked symptomatic improvement. At the MTD, paired biopsies from 4 pts (3 melanoma, 1 NSCLC) show an average 72 % decrease in pMEK, 68 % decrease in pERK, 24 % decrease in Ki67 (proliferation) and 64 % increase in TUNEL (apoptosis). Three of 6 evaluable pts in the MTD cohort show SD at first assessment, including 1 melanoma pt with a NRAS Q61R mutation who showed a 20% decrease in target lesions. Conclusions: XL281 was generally well tolerated and the MTD was established at 150 mg. One cPR occurred in an ocular melanoma subject, and clinical benefit (PR or SD) occurred in 43% (13/30) of pts in the dose-escalation phase. XL281 demonstrates biological activity by modulation of the RAF pathway in tumor and surrogate tissue, with decreases in cell proliferation and increases in apoptosis.

[Table: see text]

Experimental investigation of the timing jitter in self-pulsating quantum-dash lasers operating at 1.55 microm

We report for the first time on the systematic measurement of timing jitter of 40-GHz self-pulsating Fabry-Perot laser based on InAs/InP quantum dashes emitting at 1.55 microm. Two different methods, one based on optical cross-correlation and one on electrical spectrum sideband integration are used and show a good agreement, yielding a jitter of 0.86 ps in the 1 MHz---20 MHz frequency range with a potential of 280 fs for optimized driving conditions. Amplitude noise and high-frequency timing jitter contributions are also discussed.

Spatiotemporal patterns of postsynaptic density (PSD)-95 expression after rat spinal cord injury

AIMS

Postsynaptic density (PSD)-95 is a scaffolding protein linking the N-methyl-D-aspartate receptor with neuronal nitric oxide synthase (nNOS), which contributes to many physiological and pathological actions. We here investigated whether PSD-95 was involved in the secondary response following spinal cord injury (SCI).

METHODS

Spinal cord contusion (SCC) and spinal cord transection (SCT) models at thoracic (T) segment 9 (T(9)) were established in adults rats. Real-time polymerase chain reaction, Western blot, immunohistochemistry and immunofluorescence were used to detect the temporal profile and spatial distribution of PSD-95 after SCI. The association between PSD-95 and nNOS in the injured cords was also assessed by coimmmunoprecipation and double immunofluorescent staining.

RESULTS

The mRNA and protein for PSD-95 expression were significantly increased at 2 h or 8 h, and then gradually declined to the baseline level, ultimately up-regulated again from 5 days to 7 days for its mRNA level and at 7 days or 14 days for its protein level after either SCC or SCT. PSD-95 immunoreactivity was found in neurones, oligodendrocytes and synaptic puncta of spinal cord tissues within 5 mm from the lesion site. Importantly, injury-induced expression of PSD-95 was colabelled by active caspase-3 (apoptotic marker), Tau-1 (the marker for pathological oligodendrocytes) and nNOS.

CONCLUSIONS

Accompanied by the spatio-temporal changes for PSD-95 expression, the association between PSD-95 and nNOS undergoes substantial alteration after SCI. These two molecules are likely to form a complex on apoptotic neurones and pathological oligodendrocytes, which may in turn be involved in the secondary response after SCI.

Screening and characterization of yeasts for xylitol production

AIMS

To discover novel naturally occurring xylitol producing yeast species with potential for industrial applications.

METHODS AND RESULTS

Exactly 274 strains were cultivated on both solid and liquid screening medium with xylose as the sole carbon resource. Five strains were selected on the basis of significant growth and high degree of xylose assimilation. Their phylogenetic position was confirmed by the PCR-RFLP and sequence analysis of the D1/D2 domain of the 5' end of the large subunit rDNA gene (5'-LSU rDNA). Enzymatic analysis was conducted to compare xylose metabolism in each strain. Candida guilliermondii Xu280 and Candida maltosa Xu316 were found to have high xylose consumption rates and xylitol yields in the batch fermentation under micro-aerobic condition. The effect of the different media with high initial xylose concentration on biosynthesis of xylitol by both strains was investigated.

CONCLUSIONS

We have identified Candida spp. strains, which exhibit high levels of xylitol production from xylose suggesting that these may have potential for industrial applications.

SIGNIFICANCE AND IMPACTS OF THE STUDY

Microbial species are of importance for xylitol production. Xylitol production involves complicated metabolic regulation including xylose transport, production of key enzymes and cofactor regeneration. Thus, screening of naturally occurring xylose-utilizing micro-organisms is a viable and effective mean to obtain xylitol producing organisms with industrial application. Moreover, the research on selected strains will contribute to a better understanding of regulatory properties of xylose metabolism in different yeasts.

Cloning and molecular characterization of a gene coding D-xylulokinase (CmXYL3) from Candida maltosa

AIMS

To clone and identify a gene (CmXYL3) coding D-xylulokinase from Candida maltosa Xu316 and understand its physiological function.

METHODS AND RESULTS

Based on the conserved regions of the known D-xylulokinase-encoding genes, a pair of degenerate primers was designed to clone the CmXYL3 gene from C. maltosa Xu316. The coding region and sequences flanking the CmXYL3 gene were obtained by PCR-based DNA walking method. Southern blotting analysis suggested that there is a single copy of the CmXYL3 gene in the genome. The open reading frame starting from ATG and ending with TAG stop codon encoded 616 amino acids with a calculated molecular mass of 68889.743 Da. The CmXYL3 gene under the control of the GPD1 promoter was heterologously expressed in Saccharomyces cerevisiae deficient in D-xylulokinase (deltaScXKS1::LEU2) activity, and restored growth on D-xylulose. The specific activity of D-xylulokinase varied during xylose fermentation and was correlated with aeration level. After growth on different pentoses and pentitols as sole carbon sources, the highest specific activity of D-xylulokinase was observed on D-xylose.

CONCLUSIONS

The CmXYL3 gene isolated from C. maltosa Xu316 encodes a novel D-xylulokinase that plays a pivotal role in xylulose metabolism.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report that describes the isolation and cloning of D-xylulokinase gene (CmXYL3) from C. maltosa Xu316. D-xylulokinase is pivotal for growth and product formation during xylose metabolism. Better understanding of the biochemical properties and the physiological function of D-xylulokinase will contribute to optimizing fermentation conditions and determining the strategies for metabolic engineering of C. maltosa Xu316 for further improvement of xylitol yield and productivity.

Cre/lox-mediated marker gene excision in transgenic maize (Zea mays L.) plants

After the initial transformation and tissue culture process is complete, selectable marker genes, which are used in virtually all transformation approaches, are not required for the expression of the gene of interest in the transgenic plants. There are several advantages to removing the selectable marker gene after it is no longer needed, such as enabling the reuse of selectable markers and simplifying transgene arrays. We have tested the Cre/ lox system from bacteriophage P1 for its ability to precisely excise stably integrated marker genes from chromosomes in transgenic maize plants. Two strategies, crossing and autoexcision, have been tested and demonstrated. In the crossing strategy, plants expressing the Cre recombinase are crossed with plants bearing a transgene construct in which the selectable marker gene is flanked by directly repeated lox sites. Unlike previous reports in which incomplete somatic and germline excision were common, in our experiments complete somatic and germline marker gene excision occurred in the F(1) plants from most crosses with multiple independent Cre and lox lines. In the autoexcision strategy, the cre gene, under the control of a heat shock-inducible promoter, is excised along with the nptII marker gene. Our results show that a transient heat shock treatment of primary transgenic callus is sufficient for inducing cre and excising the cre and nptII genes. Genetic segregation and molecular analysis confirmed that marker gene removal is precise, complete and stable. The autoexcision strategy provides a way of removing the selectable marker gene from callus or other tissues such as embryos and kernels.

Screening of pyruvate-producing yeast and effect of nutritional conditions on pyruvate production

AIMS

To find a yeast strain that can overproduce pyruvate and to investigate the effect of nutrients on pyruvate production.

METHODS AND RESULTS

Trichosporon cutaneum PD70, a yeast strain that can overproduce pyruvate, was isolated from shake-flask cultures of 132 yeast strains. Pyruvate was measured by the HPLC or DNP method (see Materials and methods). Pyruvate production reached approximately 30.0 +/- 1.0 g l(-1) in basal fermentation medium. Different nutrient supplements had great effects on pyruvate production. Some of the conditions that gave the highest yield are described.

CONCLUSIONS

Exogenous thiamine supplement caused a decrease in pyruvate yield. Some amino acids, such as L-arginine, L-isoleucine and L-valine, caused a minor increase in pyruvate yield. Soybean peptone was the most suitable nitrogen source for pyruvate production. A glucose concentration of 15% in fermentation medium gave the highest yield (34.6 g l(-1)) and the highest yield against consumed glucose (0.429 g g(-1)).

SIGNIFICANCE AND IMPACT OF THE STUDY

Nutrients have significant impacts on pyruvate production. As a pyruvate overproducing yeast strain independent of exogenous vitamins or amino acids, T. cutaneum PD70 provides an advantage for commercial pyruvate production.

[Cloning and expression of VHB gene in D-arabitol producing yeast]

Recombinant plasmid pVgb-EX2 containing Vitreoscilla hemoglobin gene vgb and formaldehyde resistant gene SFA1 was constructed and transformed into D-arabitol producing yeast strain Saccharomyces sp. X-62. The fact that the amount of VHb in transformant cells was considerably higher than that in control cells indicated that gene vgb was expressed in transformant cells. D-arabitol productivity and yield of fermentation by transformants were improved. The most improvement of D-arabitol productivity in repeat experiments reached 27.3%. It appeared that the fermentation productivity of D-arabitol was relative to the amount of VHb in cells under experimental conditions.

Characterisation of the prejunctional inhibitory muscarinic receptor on cholinergic nerves in the rat urinary bladder

The nature of the prejunctional inhibitory muscarinic receptor on cholinergic nerve endings in the rat urinary bladder was investigated by measuring stimulated endogenous acetylcholine release via high pressure liquid chromatography (HPLC), in the presence of various selective muscarinic antagonists. The rank order of potencies for the antagonists used was: atropine (-log concentration = 7.8) > 4-DAMP (4-diphenylacetoxy-N-methylpiperidine) (7.6) > tripitramine (7.3) = HHD (hexahydrodifenidol) (7.3) > pFHHSiD (p-fluoro-hexahydrosiladifenidol hydrochloride) (7.0) > himbacine (6.5) > methoctramine (5.9) > or = pirenzepine (5.8) > gallamine (4.3). A comparison of the antagonist potencies obtained, with affinity constants at muscarinic M(1) to M(5) receptors, suggests that the prejunctional inhibitory muscarinic receptor is of the M(4) receptor subtype.

Establishment of latent HIV-1 infection of resting CD4(+) T lymphocytes does not require inactivation of Vpr

The introduction of highly active antiretroviral therapy (HAART) for the treatment of HIV-1 infection has allowed dramatic reductions in plasma virus levels to below the limit of detection in many patients. However, latently infected CD4(+) memory T lymphocytes persist as an important reservoir for the virus in the presence of this aggressive therapy and represent a major barrier to HIV-1 eradication with HAART. The mechanism through which the latent compartment is formed has not yet been established. It may involve actively proliferating CD4(+) T-cell intermediates that are infected with HIV-1 and revert back to a resting state, carrying integrated provirus at some low frequency. The HIV-1 accessory protein Vpr, which mediates G(2) cell cycle arrest in host cells, may interfere with the formation of the latently infected T cells by preventing them from exiting the cell cycle to return to a resting state. To investigate the role of the Vpr in the formation of latently infected memory T cells, we cloned and characterized vpr genes from viruses in the latent reservoir. Both sequence analysis and functional assays demonstrated that the vpr gene products of the viruses isolated from the latent pool did not differ significantly from those of a functional Vpr (NL4-3). These results indicate that the generation of resting G(0) memory T lymphocytes that carry latent HIV-1 provirus occurs despite the G(2) arrest function of the vpr gene product.

[Distribution of erythrocyte EsD and PGM1 (phosphoglucomutase) phenotypes in the Han population of Changsha district]

Phenotyping of erythrocyte EsD and PGM1 enzymes was performed by a mixed agarose-starch gel electrophoresis in 165 healthy blood donors of Changsha District. The gene frequencies and cumulative discrepancy power(CDP) were calculated. The phenotype frequencies of EsD and PGM1 were compared not only with the different Chinese nationalities but also with those reported by the other countries showing a good correlation with the phenotype distributions of Han people in the other cities of China. The result showed that the gene frequencies of erythrocyte EsD1 and PGM1(1) were 0.6242 and 0.7121 in Han population of Changsha District, respectively. This method is now used routinely in our laboratory and is superior for the examination of individuality and identification of paternity.

Studies on muscarinic M2 receptors in smooth muscle

Histamine after M3 receptor alkylation with 4-DAMP mustard does not serve simply as a spasmogen but facilitates visualization of the M2-mediated contraction induced by oxotremorine M. We speculate that M3 receptor activation has a similar role in untreated tissue. The facilitation appears to involve protein kinase C. The results with propranolol suggest that the phospholipase D pathway may also be important in the development of the M2-mediated response.

High viral load in the cerebrospinal fluid and brain correlates with severity of simian immunodeficiency virus encephalitis

AIDS dementia and encephalitis are complications of AIDS occurring most frequently in patients who are immunosuppressed. The simian immunodeficiency virus (SIV) model used in this study was designed to reproducibly induce AIDS in macaques in order to examine the effects of a neurovirulent virus in this context. Pigtailed macaques (Macaca nemestrina) were coinoculated with an immunosuppressive virus (SIV/DeltaB670) and a neurovirulent molecularly cloned virus (SIV/17E-Fr), and more than 90% of the animals developed moderate to severe encephalitis within 6 months of inoculation. Viral load in plasma and cerebrospinal fluid (CSF) was examined longitudinally to onset of AIDS, and viral load was measured in brain tissue at necropsy to examine the relationship of systemic and central nervous system (CNS) viral replication to the development of encephalitis. In all animals, plasma viral load peaked at 10 to 14 days postinfection and remained high throughout infection with no correlation found between plasma viremia and SIV encephalitis. In contrast, persistent high levels of CSF viral RNA after the acute phase of infection correlated with the development of encephalitis. Although high levels of viral RNA were found in the CSF of all macaques (six of six) during the acute phase, this high level was maintained only in macaques developing SIV encephalitis (five of six). Furthermore, the level of both viral RNA and antigen in the brain correlated with the severity of the CNS lesions. The single animal in this group that did not have CNS lesions had no detectable viral RNA in any of the regions of the brain. The results substantiate the use of CSF viral load measurements in the postacute phase of SIV infection as a marker for encephalitis and CNS viral replication.

Muscarinic M2 receptor-mediated contraction in the guinea pig Taenia caeci: possible involvement of protein kinase C

Contraction of the guinea pig taenia caeci is mediated by muscarinic M3 receptors; however, they comprise only 30% of the muscarinic receptors present. This study investigated the role of the predominant M2 receptor population in contractions and possible second messengers involved after M3 receptors were selectively alkylated by 4-DAMP mustard [N-(2-chloroethyl)-4-piperidinyldiphenylacetate] (60 nM) in the presence of otenzepad (AF-DX 116; 1 microM). Concentration-response curves to oxotremorine-M (oxo-M) in the presence of histamine and isoprenaline were performed in the presence of otenzepad (1 and 3 microM), resulting in a mean apparent pK(B) of 6.49, indicative of an M2 response. As the taenia has intrinsic tone, precontraction with histamine was not necessary and, therefore, in some experiments only isoprenaline was included. In these studies, an M3 response to oxo-M was observed, as the mean apparent pK(B) for otenzepad was 5.89. To investigate protein kinase C (PKC) involvement in the M2 response following M3 inactivation, the inhibitor chelerythrine (1 microM) was included with histamine and isoprenaline in the absence and presence of otenzepad. The oxo-M concentration-response curve was shifted by otenzepad with an apparent pK(B) value of 6.05, a value significantly different from that seen in the absence of chelerythrine (P < 0.05). These results suggest that activation of PKC by a spasmogen such as histamine is necessary to see an M2 response following M3 receptor inactivation.

Study on oxygen supply and protection of bone marrow in acute radiation injured mice

After irradiated by 8 Gy 60Co gamma-ray, mice were intraperitoneally injected immediately with 0.2 ml 100% compound blood-activating soup twice a day for 10 days. The in situ ulnar bone marrow partial pressure of oxygen (PbO2) was determined in vivo before, during and after irradiation respectively. The bone marrow sections in the same part were observed. Our results showed that the normal murine ulnar PbO2 was 12.72 +/- 1.05 kPa. During irradiation, the level of PbO2 decreased to 10.78 +/- 1.17 kPa (P < 0.001). And 3 days after irradiation, PbO2 decreased to 9.75 +/- 0.52 kPa, suggesting that the commonly used "blood-activating and stasis-eliminating" Chinese drugs could promote the rehabilitation and proliferation of bone marrow microvessels in the acute radiation injured mice, expand their areas, increase the oxygen supply of bone marrow microenvironment, thereby leading to PbO2 much higher increase than that of control group. It is also helpful in the proliferation and rehabilitation of hematopoietic cells.

Experimental study on distribution of serotypes and antimicrobial patterns of group B streptococcus strains

OBJECTIVE

To obtain information on the distribution of serotypes and antimicrobial agent susceptibilities to group B streptococcus (GBS) strains isolated in Beijing area from 1991 to 1996.

METHODS

Bacterial isolates of GBS were obtained from vaginal and cervical tract of pregnant and nonpregnant women in Beijing Tian Tan Hospital by culture. A total of 76 GBS strains were identified finally by coagglutination. Serotyping was determined by Standard Lancefield method. Susceptibility to test agents was assessed by determining the minimal inhibitory concentrations (MICs) with agar dilution method that was established by the National Committee for Clinical Laboratory Standards (NCCLS).

RESULTS

Seven serotypes were identified among 76 GBS strains isolates. Types II (33%), III (23%) and I a (16%) were the predominant serotypes in pregnant and nonpregnant women. MICs of penicillin G and ampicillin were < or = 0.06 microgram/ml. MICs of cephazolin, cefuroxime and cefoperozone were 0.003 microgram/ml-0.06 microgram/ml. MICs of erythromycin were 0.003 microgram/ml-0.03 microgram/ml. MICs of gentamycin were 1 microgram/ml-32 micrograms/ml. MICs of amikacin were 4 micrograms/ml- > or = 64 micrograms/ml, nearly 12.8% and 40.4% of the strains were resistant to gentamycin and amikacin, respectively.

CONCLUSIONS

Our study provides useful epidemiologic data for preparation of GBS type-specific vaccines which can prevent GBS infections and antimicrobial agents susceptibility patterns in China. Routine reports on GBS susceptibilities by clinical laboratories and continuous surveillance for changes in the susceptibility are of considerable clinical importance.

Chirp measurement of multimode q-switched laser diode pulses by use of a streak camera and a grating monochromator

We discuss spectrotemporal measurements of laser diode pulses performed with a streak camera and a grating monochromator to yield a precise evaluation of chirping effects in Q-switched multimode emissions. We experimentally illustrate several causes of errors, depending on the grating size and period as well as on the adjustment of the collimating lens at the monochromator output. An analytical formula is derived that allows us to relate the chirp amplitude to the inclination of the modal structures in the streak image. Two configurations are proposed for a practical determination of the chirp amplitude in multimode emissions. Illustrations are provided with Q-switched AlGaAs laser diodes that exhibit chirp amplitudes larger than the mode spacing.

A new approach to indirect bonding using light-cure composites

Indirect bonding offers many advantages over direct bonding. The ability to better visualize teeth for proper bracket placement and reduced chair time leads to a less stressful bonding experience for the orthodontist. Conventional approaches to indirect bonding have relied on transfer trays made of materials that are not transparent. After these trays are placed on teeth, one cannot ensure proper seating of the tray and, because of their opaque nature, the orthodontist must use self-cure composites that are very difficult to remove around the brackets after the tray is removed. A new approach has been proposed in this article, which significantly modifies the fabrication of the indirect bonding transfer tray and provides direct visualization and access to the brackets during both the laboratory and clinical stages of the procedure. Furthermore, the orthodontist may use light-cure composite resins, clean off excess composite around the brackets, and apply light curing when fully satisfied with bracket position and hygiene.

Inhibition by endothelin-1 of cholinergic nerve-mediated acetylcholine release and contraction in sheep isolated trachea

1. The relative roles of ETA and ETB receptor activation on cholinergic nerve-mediated contraction and acetylcholine (ACh) release were examined in sheep isolated tracheal smooth muscle. 2. Electrical field stimulation (EFS; 90 V, 0.5 ms duration, 1 Hz, 10 s train) applied to sheep isolated tracheal smooth muscle strips induced monophasic contractile responses that were abolished by either 1 microM tetrodotoxin or 0.1 microM atropine, but were insensitive to 10 microM hexamethonium and 100 microM L-NAME. Thus, EFS-induced contractions resulted from the spasmogenic actions of ACh released from parasympathetic, postganglionic nerves. 3. As expected, sheep isolated tracheal smooth muscle preparations did not contract in response to the ETB receptor-selective agonist, sarafotoxin S6c (0.1-100 nM). However, sarafotoxin S6c caused a concentration-dependent and transient inhibition of EFS-induced contractions. The inhibitory effect induced by a maximally effective concentration of sarafotoxin S6c (10 nM; 72.1 +/- 5.7%, n = 6) was abolished in the presence of the ETB receptor-selective antagonist BQ-788 (1 microM). Contractile responses to exogenously administered ACh (10 nM-0.3 mM) were not inhibited by sarafotoxin S6c (1 or 10 nM; n = 7). 4. In contrast to sarafotoxin S6c, endothelin-1 induced marked contractions in sheep isolated tracheal smooth muscle. These contractions were inhibited by BQ-123, consistent with an ETA receptor-mediated response. In the presence of BQ-123 (3 microM), endothelin-1 produced a concentration-dependent inhibition of EFS-induced contractions (30 nM endothelin-1, 68.9 +/- 10.2% inhibition, n = 5). These responses were inhibited by 1 microM BQ-788, indicative of an ETB receptor-mediated process. Endothelin-1 was about 3 fold less potent than sarafotoxin S6c. 5. EFS (90 V, 0.5 ms duration, 1 Hz, 15 min train) induced the release of endogenous ACh (1.94 +/- 0.28 pmol mg-1 tissue, n = 12), as assayed by h.p.l.c. with electrochemical detection. EFS-induced release of ACh was inhibited to a similar extent by 100 nM endothelin-1 (47 +/- 4%, n = 9) and 10 nM sarafotoxin S6c (46 +/- 9%, n = 3). These effects of endothelin-1 on ACh release were inhibited by 1 microM BQ-788 alone (n = 4), by BQ-788 in the presence of 3 microM BQ-123 (n = 4), but not by 3 microM BQ-123 alone (n = 5). 6. In summary, sheep isolated tracheal smooth muscle contains two anatomically and functionally distinct endothelin receptor populations. ETA receptors located on airway smooth muscle mediate contraction, whereas ETB receptors appear to exist on cholinergic nerves that innervate tracheal smooth muscle cells and mediate inhibition of ACh release. The inhibitory effect of ETB receptor stimulation on cholinergic neurotransmission is in stark contrast to the enhancing effects hitherto described in the airways.

Transesophageal assessment of coronary flow velocity reserve during "regular" and "high"-dose dipyridamole stress testing

To assess the effect of regular and high-dose dipyridamole on coronary flow velocity in the left anterior descending artery (LAD), and to determine whether assessment of coronary flow velocity reserve (CFVR) is more sensitive for detection of ischemia than standard echocardiographic criteria, 47 patients were studied prospectively: 16 patients with stenosis of the LAD, 18 patients with angiographically normal LADs, and 13 patients with minimal disease. Patients underwent transesophageal echocardiographic study of wall motion and LAD flow velocity at baseline and at hyperemia, and for angina and electrocardiographic changes. The mean CFVR values after 0.56 mg/kg after 0.84 mg/kg of dipyridamole were similar: 2.52 +/- 0.87 versus 2.62 +/- 0.90. A CFVR <2.3 (normals mean -2 SDs) was more sensitive (88% at both doses) for the detection of underlying coronary obstruction than was wall motion monitoring (44% and 75%, respectively). The combination of CFVR <2.3 and wall monitoring was more sensitive than index alone (94% at both 0.56 and 0.84 mg/kg). The rate-pressure product was not significantly different at the two doses of dipyridamole. When flow response is the end point of stress testing, as with transesophageal monitoring, the 0.56 mg/kg dose of dipyrid mole is adequate, but when ischemia is the end point (as with wall motion monitoring by 2-dimensional echocardiography), the dose of 0.84 mg/kg is more sensitive.

High-level production of recombinant proteins in CHO cells using a dicistronic DHFR intron expression vector

We have constructed expression vectors for Chinese hamster ovary (CHO) cells that produce both selectable marker and recombinant cDNA from a single primary transcript via differential splicing. These vectors produce stable CHO cell clones that, when pooled, produce abundant amounts of secreted recombinant proteins compared with the amounts produced by conventional expression approaches that have selectable marker and the cDNA of interest under control of separate transcription units. Our vectors divert most of the transcript to product expression while linking it, at a fixed ratio, to dihydrofolate reductase (DHFR) expression to allow selection of stable transfectants. Pools of clones with increased expression of the product gene can be efficiently generated by selection in methotrexate. The high level of expression from pools allows convenient and rapid production of milligram amounts of recombinant proteins.

Extraction of acetylcholine and choline from physiological solutions for analysis by HPLC

A method is described for extracting and concentrating acetylcholine and choline released from cholinergic nerve stimulation in isolated tissue preparations.

[The follow-up survey of results of radial keratotomy]

We reviewed 119 cases of consecutive radial keratotomies of 67 patients who were followed up for three years to evaluate the stability and safety of the surgery. The average change of overall refraction was -0.12D between one year and three years after the surgery, which was statistically insignificant. Stable refractive results were achieved in 72.3% of the eyes. 16.8% of the eyes experienced an increase from -1.00D to 2.50D, and 10.9% displayed a decrease from 1.00D to 3.50D. Eyes with preoperative high myopia were more likely to cause significant postoperative refractive change. In three years, 8.5% of the eyes gained the best corrected visual acuity of two to four lines. 2.6% of the eyes lost two lines because of macular disorders. Specular microscopy indicated that there was no significant change in corneal endothelial cell density following radial keratotomy.

Eleven-year experience with radial keratotomy

1,900 consecutive eyes that underwent radial keratotomy by the senior author were evaluated retrospectively. 3 months after surgery, minimum reduction in mean spherical equivalent of 0.67D was achieved with 1 incision and maximum 7.25D with 24 incisions. Uncorrected visual acuity of 20/40 or better was obtained in 99.4% of eyes with low myopia, 64.2% with moderate myopia and 32.4% with high myopia. For anisometropia, bilateral RK reduced refractive error from -12. 12D to -5. 22D in more myopic eyes and -8. 18D to -3. 4D in less myopic eyes and unilateral surgeries reduced refractive error from -9. 45D to -3. 85D. Anisometropia after surgery became clinically and physically acceptable and aniseikonia was significantly improved. No vision threatening complications occurred. Our results indicate that radial keratotomy is a relatively safe and effective surgical procedure for myopia.

Characterization of the muscarine receptor subtype on sympathetic nerve endings in the rat caudal artery

The prejunctional muscarine receptor on sympathetic nerves in the rat caudal artery was characterized using several selective antagonists. The inhibitory response of carbachol on vasoconstriction elicited by sympathetic nerve stimulation was antagonized by benzhexol (trihexyphenidyl; pKB 7.1), heptane-1,7-bis(dimethyl-3'-phthalimidopropyl ammonium bromide) (C7/3-phth; pKB 6.5) and hexahydrosiladifenidol (HHSiD; apparent pKB 6.0). These pKB values suggest that the receptor most closely resembles the muscarine M2 receptor subtype rather than the muscarine M1, M3 or M4 receptor subtypes.