The impact of volunteer service on moral education performance and mental health of college students

BACKGROUND

Moral education in colleges and universities is an important part of the talent training system, including moral education curriculum, moral education practice, mental health education. Volunteer service is a public welfare act in which volunteers volunteer their time, knowledge, property, technology, with the ultimate goal of helping others and serving the society without personal compensation. As an innovative form of moral education practice in colleges and universities, college students' voluntary service is of great significance in promoting the reform and innovation of moral education, enhancing the affinity, appeal and influence of moral education, and building a positive psychology for college students.

SUBJECTS AND METHODS

As an effective carrier of moral education practice in colleges and universities, voluntary service is helpful to enhance the effectiveness of moral education practice and construct the positive psychology of college students. This project is based on the actual situation of college students participating in volunteer services, and collected the volunteer services of 4545 college students in Zhejiang Province. Through model construction and data modeling, the correlation between college students' participation in volunteer service and their moral education performance and mental health was analyzed, and the basic path and guarantee measures to promote the role of volunteer service in moral education and positive psychological construction were deeply explored.

RESULTS

From the correlation analysis of students' voluntary service participation, moral education performance and voluntary service motivation, students' attributes are determined according to their voluntary service participation, so as to predict their moral education performance and mental health level.

CONCLUSION

College students' voluntary service is partially positively related to their moral education performance and mental health. In order to improve students' moral education performance and mental health, we can optimize the participation frequency, participation duration, participation ways and type structure of voluntary service, constantly increase the participation frequency of voluntary service, increase the duration of voluntary service, broaden the participation ways of voluntary activities, and enrich the types of voluntary service activities.

Development and validation of survival nomograms for patients with differentiated thyroid cancer with distant metastases: a SEER Program-based study

BACKGROUND

We aimed to develop a nomogram model of overall survival (OS) and cancer-specific survival (CSS) in patients with differentiated thyroid cancer with distant metastases, and to evaluate and validate the nomogram. Also, its prognostic value was compared with that of the 8th edition of the American Joint Committee on Cancer tumor-node-metastasis staging system (AJCC8SS).

METHODS

Patients with distant metastatic differentiated thyroid cancer (DMDTC) from 2004 to 2015 were selected from the Surveillance, Epidemiology, and End Results (SEER) Program to extract the clinical variables used for analysis. A total of 906 patients were divided into a training set (n = 634) and validation set (n = 272). OS and CSS were selected as the primary end point and secondary end point. LASSO regression analysis and multivariate Cox regression analysis were applied to screen variables for constructing OS and CSS nomograms for survival probability at 3, 5, and 10 years. Nomograms were evaluated and validated using the consistency index (C-index), time-dependent receiver operator characteristic (ROC) curves, area under the ROC curve, calibration curves, and decision curve analysis (DCA). The predictive survival of the nomogram was compared with that of AJCC8SS. Kaplan-Meier curves and log-rank tests were used to evaluate the risk-stratification ability OS and CSS nomograms.

RESULTS

CS and CSS nomograms included six independent predictors: age, marital status, type of surgical procedure, lymphadenectomy, radiotherapy, and T stage. The C-index for the OS nomogram was 0.7474 (95% CI = 0.7199-0.775), and that for the CSS nomogram was 0.7572 (0.7281-0.7862). The nomogram showed good agreement with the "ideal" calibration curve in the training set and validation sets. DCA confirmed that the survival probability predicted by the nomogram had high clinical predictive value. The nomogram could stratify patients more accurately, and showed more robust accuracy and predictive power, than AJCC8SS.

CONCLUSIONS

We established and validated prognostic nomograms for patients with DMDTC, which had significant clinical value compared with AJCC8SS.

A multi-view contrastive learning for heterogeneous network embedding

Graph contrastive learning has been developed to learn discriminative node representations on homogeneous graphs. However, it is not clear how to augment the heterogeneous graphs without substantially altering the underlying semantics or how to design appropriate pretext tasks to fully capture the rich semantics preserved in heterogeneous information networks (HINs). Moreover, early investigations demonstrate that contrastive learning suffer from sampling bias, whereas conventional debiasing techniques (e.g., hard negative mining) are empirically shown to be inadequate for graph contrastive learning. How to mitigate the sampling bias on heterogeneous graphs is another important yet neglected problem. To address the aforementioned challenges, we propose a novel multi-view heterogeneous graph contrastive learning framework in this paper. We use metapaths, each of which depicts a complementary element of HINs, as the augmentation to generate multiple subgraphs (i.e., multi-views), and propose a novel pretext task to maximize the coherence between each pair of metapath-induced views. Furthermore, we employ a positive sampling strategy to explicitly select hard positives by jointly considering semantics and structures preserved on each metapath view to alleviate the sampling bias. Extensive experiments demonstrate MCL consistently outperforms state-of-the-art baselines on five real-world benchmark datasets and even its supervised counterparts in some settings.

Multi-Attribute Decision Making with Einstein Aggregation Operators in Complex Q-Rung Orthopair Fuzzy Hypersoft Environments

The purpose of our research is to extend the formal representation of the human mind to the concept of the complex q-rung orthopair fuzzy hypersoft set (Cq-ROFHSS), a more general hybrid theory. A great deal of imprecision and ambiguity can be captured by it, which is common in human interpretations. It provides a multiparameterized mathematical tool for the order-based fuzzy modeling of contradictory two-dimensional data, which provides a more effective way of expressing time-period problems as well as two-dimensional information within a dataset. Thus, the proposed theory combines the parametric structure of complex q-rung orthopair fuzzy sets and hypersoft sets. Through the use of the parameter q, the framework captures information beyond the limited space of complex intuitionistic fuzzy hypersoft sets and complex Pythagorean fuzzy hypersoft sets. By establishing basic set-theoretic operations, we demonstrate some of the fundamental properties of the model. To expand the mathematical toolbox in this field, Einstein and other basic operations will be introduced to complex q-rung orthopair fuzzy hypersoft values. The relationship between it and existing methods demonstrates its exceptional flexibility. The Einstein aggregation operator, score function, and accuracy function are used to develop two multi-attribute decision-making algorithms, which prioritize based on the score function and accuracy function to ideal schemes under Cq-ROFHSS, which captures subtle differences in periodically inconsistent data sets. The feasibility of the approach will be demonstrated through a case study of selected distributed control systems. The rationality of these strategies has been confirmed by comparison with mainstream technologies. Additionally, we demonstrate that these results are compatible with explicit histograms and Spearman correlation analyses. The strengths of each approach are analyzed in a comparative manner. The proposed model is then examined and compared with other theories, demonstrating its strength, validity, and flexibility.

MR Imaging Differences in the Circle of Willis between Healthy Children and Adults

BACKGROUND AND PURPOSE

Asymmetries in the circle of Willis have been associated with several conditions, including migraines and stroke, but they may also be age-dependent. This study examined the impact of age and age-dependent changes in cerebral perfusion on circle of Willis anatomy in healthy children and adults.

MATERIALS AND METHODS

We performed an observational, cross-sectional study of bright and black-blood imaging of the proximal cerebral vasculature using TOF-MRA and T2 sampling perfection with application-optimized contrasts by using different flip angle evolution (T2-SPACE) imaging at the level of the circle of Willis in 23 healthy children and 43 healthy adults (4-74 years of age). We compared arterial diameters measured manually and cerebral perfusion via pseudocontinuous arterial spin-labeling between children and adults.

RESULTS

We found that the summed cross-sectional area of the circle of Willis is larger in children than in adults, though the effect size was smaller with T2-SPACE-based measurements than with TOF-MRA. The circle of Willis is also more symmetric in children, and nonvisualized segments occur more frequently in adults than in children. Moreover, the size and symmetry of the circle of Willis correlate with cerebral perfusion.

CONCLUSIONS

Our results demonstrate that the circle of Willis is different in size and symmetry in healthy children compared with adults, likely associated with developmental changes in cerebral perfusion. Further work is needed to understand why asymmetric vasculature develops in some but not all adults.

Enhanced antitumor effect of combining TRAIL and MnSOD mediated by CEA-controlled oncolytic adenovirus in lung cancer

Lung cancer, especially adenocarcinoma, is one of the leading causes of death in the world. Carcinoembryonic antigen (CEA), a superb non-small-cell lung cancer marker candidate, showed a beneficial effect in cancer therapy with oncolytic adenovirus in recent studies. Cancer-targeting dual gene-virotherapy delivers two therapeutic genes, linked by a connexon, in the replication-deficient vector instead of one gene so that they can work in common. In this study, we constructed a tumor-specific oncolytic adenovirus, CD55-TRAIL-IETD-MnSOD. The virus has the fusion protein complementary DNAs for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and for manganese superoxide dismutase (MnSOD) complementary DNA linked through a 4-amino acid caspase-8 cleavage site (IETD), and uses a CEA promoter to control virus E1A express. This is the first work to use a CEA promoter-regulated oncolytic adenovirus carrying two therapeutic genes for cancer research. Its targeting and anticancer capacity was evaluated by in vitro and in vivo experiments. The results indicated that CD55-TRAIL-IETD-MnSOD caused more cell apoptosis than CD55-TRAIL or CD55-MnSOD alone, or their combination in vitro, with low cytotoxicity of normal cells. In the A549 tumor xenograft model in nude mice, data showed that CD55-TRAIL-IETD-MnSOD could effectively suppress tumor growth than single gene groups, with no histological damage in liver, spleen or kidney tissues. Thus, the CEA-regulated dual-gene oncolytic virus CD55-TRAIL-IETD-MnSOD may be a novel potential therapy for lung cancer.

Deficiency of antithrombin and protein C gene in 202 Chinese venous thromboembolism patients

INTRODUCTION

Antithrombin and protein C gene deficiencies are commonly inherited risk factors for VTE patients. We aim to investigate the deficiency of these two gene in 202 Chinese patients with venous thromboembolism (VTE).

METHODS

Antithrombin activity (AT: A) and protein C activity (PC: A) were measured in 202 VTE patients, and for those with unexplainable low results, PCR and direct sequencing of the related genes were carried out.

RESULTS

Deficiency levels of antithrombin and protein C gene were found to be 2% and 8%, respectively. AT or PC hereditary deficiency can be found in 10% patients with VTE.

CONCLUSION

Protein C gene deficiency might be more prevalent than AT gene deficiency in Chinese VTE patients. Functional assay combined with genetic analysis is useful in the diagnosis of inherited defects in VTE patients.

Reduction of osteopontin in vivo inhibits tubular epithelial to mesenchymal transition in rats with chronic allograft nephropathy

OBJECTIVE

Chronic allograft nephropathy (CAN) is an important etiological factor causing graft loss. However, the mechanism of CAN is unclear. Osteopontin (OPN), a proinflammatory and profibrosis molecule, plays a key role in late stages of renal diseases. We investigated the potential role of OPN in the pathogenesis of CAN.

METHODS

Using a F344 to Lewis rat CAN model, we injected short hairpin RNA (shRNA) constructs targeting OPN or negative control plasmids through the renal vein following electroporation. At 12 weeks after the transplantation, we determined interstitial fibrosis (IF) and tubular atrophy (TA) of the tubular epithelial cells (TECs). OPN expression was examined using Western blots and immunohistochemistry (IHC). Molecules involved in epithelial to mesenchymal transition (EMT) of TECs were examined using IHC and Western blots.

RESULTS

OPN expression in kidney grafts was decreased by the RNA interference (RNAi) group. Histology observations showed IF and TA to be mild with stable renal function in the RNAi-treated group. EMT of TECs was significantly lessened after reducing OPN.

CONCLUSION

Reduction of OPN in vivo inhibited progression of CAN. OPN may be of therapeutic value in transplantation settings.

Comparison of risk factors associated with hypertension subtypes by classification tree method in Tongshan County of Jiangsu Province, China

BACKGROUND

There are only a very limited number of studies relating to risk factors for hypertension in rural populations in China. There are even fewer studies comparing various hypertension subtypes.

METHODS

A cross-sectional investigation was carried out in a representative sample of 20,390 subjects drawn from among 1,180,000 adult residents of Tongshan County of Jiangsu Province, China. The impact of risk factors including demographic, socioeconomic, dietary, and behavioral, on three hypertension subtypes, namely, isolated systolic hypertension (ISH), isolated diastolic hypertension (IDH), and systolic-diastolic hypertension (SDH), was analyzed by applying statistical tests and a classification tree.

RESULTS

ISH was the predominant untreated hypertension subtype (13.68 +/- 0.24%) in the adults of Tongshan County, followed by SDH (11.70 +/- 0.23%) and IDH (6.24 +/- 0.17%). Age, number of cigarettes smoked daily, and the types of vitamins taken varied among the ISH, IDH, and SDH classification trees. Low socioeconomic status was associated with an increased risk for ISH and SDH. Light alcohol intake was associated with higher risk for ISH, but with lower risks for IDH and SDH. Light cigarette smoking was associated with higher ISH risk but lower SDH risk. The intake of appropriate amounts of fish, shrimp, or meat lowered the risks for ISH and IDH. The intake of appropriate amounts of seafood, eggs, milk, or fruit lowered the risks for all hypertension subtypes. Interestingly, an excessive preference for sweet or salty foods was associated with a higher risk for all the subtypes.

CONCLUSIONS

In Tongshan County, there was a considerable prevalence of hypertension of various subtypes, each associated with distinctive and complex risk factors. This suggests that there is a need for testing more diverse prevention measures, tailored to specific subtypes.

Growth inhibition of human endothelial cells by the phyto-oestrogen biochanin A, a metabolite of genistein

This study examined the growth regulatory effects of a phyto-oestrogen, biochanin A, on a transformed human endothelial cell line ECV304in vitro. Biochanin A was found to inhibit cell proliferation in a dose-dependent fashion and this effect was influenced by the concentration of serum present in the culture medium. In the absence of serum, the calculated IC50of biochanin A was 0.18 ± 0.1 μM COMPARED TO AN IC50OF 35±5 Μm at 10 % serum. At low cell density, the growth inhibitory effects of biochanin A were more evident than at high cell density. Co-administration of a synthetic oestrogen diethylstilboestrol with biochanin A did not suppress the growth regulatory effects of biochanin A treatment. We conclude that biochanin A inhibits the cell proliferation of human endothelial cells at concentrations that are physiologically achievablein vivoand that this effect may play an important role in the cancer-preventing activity of the phyto-oestrogens.

CDX2 has tumorigenic potential in the human colon cancer cell lines LOVO and SW48

CDX2 is a Drosophila caudal-related homeobox transcription factor that is important for the establishment and maintenance of intestinal epithelial cells. CDX2 is a marker of colon cancer, with strong staining in up to 90% of colonic adenocarcinomas. CDX2 heterozygous-null mice develop colonic neoplasms, which have suggested that CDX2 is a tumor suppressor. However, CDX2 has not been reported to affect xenograft growth. Furthermore, CDX2 is rarely mutated in colon cancer, which has led to suggestions that it may play only a minor role as a tumor suppressor in colon cancer. To understand the functional contributions of CDX2 to colon cancer, we disrupted CDX2 in LOVO and SW48 human colon cancer cell lines by targeted homologous recombination. Consistent with the literature, disruption of CDX2 enhanced anchorage-dependent cell proliferation. However, homozygous loss of CDX2 led to significant inhibition of anchorage-independent growth in LOVO cells, and cell lethality in SW48 cells. Further analyses revealed that disruption of CDX2 led to anchorage-independent G1 to S growth arrest and anoikis. In vivo xenograft studies confirmed that disruption of CDX2 inhibited LOVO tumor growth. These data demonstrate that CDX2 mediates anchorage-independent growth and survival. Thus, CDX2 has tumorigenic potential in the human colon cancer cell lines LOVO and SW48.

Antiviral potential of a new generation of acyclic nucleoside phosphonates, the 6-[2-(phosphonomethoxy)alkoxy]-2,4-diaminopyrimidines

Three acyclic nucleoside phosphonates (ANPs) have been formally approved for clinical use in the treatment of 1) cytomegalovirus retinitis in AIDS patients (cidofovir, by the intravenous route), 2) chronic hepatitis B virus (HBV) infections (adefovir dipivoxil, by the oral route), and 3) human immunodeficiency virus (HIV) infections (tenofovir disoproxil fumarate, by the oral route). The activity spectrum of cidofovir {(S)- 1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine [(S)-HPMPC)]}, like that of (S)-HPMPA [(S)-9-[3-hydroxy-2-(phosphonomethoxy)propyl]adenine) and (S)-HPMPDAP [(S)-9-[3-hydroxy-2-(phosphonomethoxy)propyl]-2, 6-diaminopurine), encompasses a broad spectrum of DNA viruses, including polyoma-, papilloma-, adeno-, herpes-, and poxviruses. Adefovir {9-[2-(phosphonomethoxy)ethyl]adenine (PMEA)} and tenofovir [(R)-9-[2-(phosphonomethoxy) propyl]adenine [(R)-PMPA)]} are particularly active against retroviruses (ie., HIV) and hepadnaviruses (ie., HBV); additionally, PMEA also shows activity against herpes- and poxviruses. We have recently identified a new class of ANPs, namely 6-[2-(phosphonomethoxy)alkoxy]-2,4-diaminopyrimidines, named, in analogy with their alkylpurine counterparts, HPMPO-DAPy, PMEO-DAPy, and (R)-PMPO-DAPy. These compounds exhibit an antiviral activity spectrum and potency that is similar to that of (S)-HPMPDAP, PMEA, and (R)-PMPA, respectively. Thus, PMEO-DAPy and (R)-PMPO-DAPy, akin to PMEA and (R)-PMPA, proved particularly active against HIV- 1, HIV-2, and the murine retrovirus Moloney sarcoma virus (MSV). PMEO-DAPy and (R)-PMPO-DAPy also showed potent activity against both wild-type and lamivudine-resistant strains of HBV. HPMPO-DAPy was found to inhibit different poxviruses (ie., vaccinia, cowpox, and orf) at a similar potency as cidofovir. HPMPO-DAPy also proved active against adenoviruses. In vivo, HPMPO-DAPy proved equipotent to cidofovir in suppressing vaccinia virus infection (tail lesion formation) in immunocompetent mice and promoting healing of disseminated vaccinia lesions in athymic-nude mice. The 6-[2-(phosphonomethoxy)alkoxy]-2,4-diaminopyrimidines offer substantial potential for the treatment of a broad range of retro-, hepadna-, herpes-, adeno-, and poxvirus infections.

Novel acyclic nucleoside phosphonate analogues with potent anti-hepatitis B virus activities

Novel acyclic nucleoside phosphonates with a pyrimidine base preferentially containing an amino group at C-2 and C-4 and a 2-(phosphonomethoxy)ethoxy or (R)-2-(phosphonomethoxy)propoxy group at C-6 selectively inhibit the replication of wild-type and lamivudine-resistant hepatitis B viruses. The activity of the most potent compounds was comparable to that of adefovir.

Effects of the dietary phytoestrogen biochanin A on cell growth in the mammary carcinoma cell line MCF-7

Studies of the dietary phytoestrogen biochanin A on cell proliferation of the cultured estrogen responsive cells human breast carcinoma MCF-7 showed that biochanin A exhibits biphasic regulation on MCF-7 cells. At concentrations of less than 10 microg/mL, cells respond to biochanin A by increasing cell growth and de novo DNA synthesis. The addition of biochanin A at concentrations of greater than 30 microg/mL significantly inhibited cell growth and DNA synthesis in a dose-dependent fashion, resulting in an IC(50) value of 40 microg/mL. The reversibility of these inhibitory effects by biochanin A appears also to be concentration dependent. Cells previously treated with high concentrations (>60 microg/mL) of biochanin A did not regain normal growth after treatment ceased. Biochanin A was cytostatic at low concentrations (<40 microg/mL) and cytotoxic at higher concentrations. Upon exposure to 100 microg/mL of biochanin A, cell morphology was severely altered, cell volume decreased, and condensation of cell components was clearly noticeable. In addition, biochanin A damaged cell membranes by increasing membrane permeability. These results suggest possible molecular and cellular mechanisms of the action of dietary phytoestrogens on estrogen target cells.

Sulphated and sulphonated polymers inhibit the initial interaction of hepatitis B virus with hepatocytes

The initial step during hepatitis B virus (HBV) infection is the specific attachment of the virus to the hepatocyte. Here we studied whether the binding of HBV to hepatocytes can, as is the case with most other enveloped viruses, be blocked by polyanionic compounds. Viral particles produced by HepAD38 cells were used as inoculum and HBV-negative HepG2 cells, as well as primary human hepatocytes, as target cells. Three sulphated polymers, that is, PAVAS (a co-polymer of acrylic acid with vinyl alcohol sulphate), heparin and dextran sulphate (DS) (MW 5000), and the sulphonated polymer PAMPS [poly(2-acryl-amido-2-methyl-1-propanesulfonic acid] (MW approximately 7000-12000), proved strong inhibitors of the binding of HBV to HepG2 cells and primary hepatocytes. The 50% effective concentration (EC50) for inhibition of HBV binding to HepG2 cells by PAVAS, heparin, DS and PAMPS was 1.3 microg/ml, 1.6 microg/ml, 1.8 microg/ml and 3.3 microg/ml, respectively, and to primary hepatocytes 1.6 microg/ml (PAVAS), 1.6 microg/ml (heparin), 2.6 microg/ml (DS) and 4.1 microg/ml (PAMPS). These values are in the same range as the concentrations required for these compounds to prevent such viruses as herpesviruses and HIV from binding to cells. These findings may be helpful in elucidating the mechanism of the initial interaction of HBV with hepatocytes.

Carrier-mediated delivery improves the efficacy of 9-(2-phosphonylmethoxyethyl)adenine against hepatitis B virus

We recently synthesized a lipophilic prodrug of 9-(2-phosphonyl-methoxyethyl)adenine (PMEA), designated PMEA-LO, and incorporated it into reconstituted lactosylated high-density lipoprotein (LacNeoHDL). In a rat model, LacNeoHDL-associated PMEA-LO was internalized by the asialoglycoprotein receptor on parenchymal liver cells and converted into its active diphosphorylated metabolite. To further evaluate the therapeutic potential of the carrier-associated prodrug, we examined in this study the processing of (125)I-labeled PMEA-LO--loaded LacNeoHDL by HepG2 cells. Upon incubation with HepG2 cells, PMEA-LO--loaded LacNeoHDL became rapidly cell-associated. The association was saturable and of high-affinity (k(d) = 3.8 +/- 0.4 nM). Asialofetuin, an established ligand for the asialoglycoprotein receptor, inhibited the association by >75%, which confirms the role of the asialoglycoprotein receptor. Association of the prodrug-loaded particles to HepG2 cells was coupled to degradation. Radiolabeled degradation products appeared in the culture medium with a lag phase of 2 h. Asialofetuin and chloroquine inhibited secretion of degradation products by 75 to 80%, indicating that PMEA-LO--loaded LacNeoHDL is internalized via the asialoglycoprotein receptor and lysosomally processed. The therapeutic potential of LacNeoHDL-associated PMEA-LO was studied by measuring its effects on hepatitis B virus (HBV) replication in Hep AD38 cells (HBV-transfected HepG2 cells). LacNeoHDL-associated PMEA-LO effectively inhibited HBV DNA synthesis. The EC(50) value of carrier-associated PMEA-LO was 35 times lower than that of free PMEA (3.4 +/- 0.4 and 120 +/- 18 ng of PMEA/ml, respectively). We conclude that the present results, combined with our earlier in vivo disposition data, underscore the therapeutic potential and utility of PMEA-LO--loaded LacNeoHDL for treatment of chronic hepatitis B.

Case-controlled study on relevant factors of adolescent sexual coercion in China

This was a case-controlled study to determine factors related to sexual coercion among adolescent abortion seekers in China. We considered the abortion-seeking women who had experienced sexual coercion as the case group and the abortion-seeking women who had never experienced sexual coercion as the control group. The results of the study indicated that the factors more likely to be related to sexual coercion include lower educational level [odds ratio (OR) = 1.55], not living with parents (OR) = 1.57, floating population (OR = 1.63), beaten by her partner (OR = 2.87), abused by her partner (OR = 1.84), multiple partners (OR = 2.10), sex after excessive drinking (OR = 5.02), younger age at first intercourse (OR = 1.68), and large difference in age between men and women (OR = 2.02). The relevant factors most likely to be associated with sexual coercion are poorly educated, not living with parents, floating population, multiple partners, younger age at first sex, and inequality between men and women.

Acyclic/carbocyclic guanosine analogues as anti-herpesvirus agents

Several guanosine analogues, i.e. acyclovir (and its oral prodrug valaciclovir), penciclovir (in its oral prodrug form, famciclovir) and ganciclovir, are widely used for the treatment of herpesvirus [i.e. herpes simplex virus type 1 (HSV-1), and type 2 (HSV-2), varicella-zoster virus (VZV) and/or human cytomegalovirus (HCMV)] infections. In recent years, several new guanosine analogues have been developed, including the 3-membered cyclopropylmethyl and -methenyl derivatives (A-5021 and synguanol) and the 6-membered D- and L-cyclohexenyl derivatives. The activity of the acyclic/carbocyclic guanosine analogues has been determined against a wide spectrum of viruses, including the HSV-1, HSV-2, VZV, HCMV, and also human herpesviruses type 6 (HHV-6), type 7 (HHV-7) and type 8 (HHV-8), and hepatitis B virus (HBV). The new guanosine analogues (i.e. A-5021 and D- and L-cyclohexenyl G) were found to be particularly active against those viruses (HSV-1, HSV-2, VZV) that encode for a specific thymidine kinase (TK), suggesting that their antiviral activity (at least partially) depends on phosphorylation by the virus-induced TK. Marked antiviral activity was also noted with A-5021 against HHV-6 and with D- and L-cyclohexenyl G against HCMV and HBV. The antiviral activity of the acyclic/carbocyclic nucleoside analogues could be markedly potentiated by mycophenolic acid, a potent inhibitor of inosine 5'-monophosphate (IMP) dehydrogenase. The new carbocyclic guanosine analogues (i.e. A-5021 and D- and L-cyclohexenyl G) hold great promise, not only as antiviral agents for the treatment of herpesvirus infections, but also an antitumor agents for the combined gene therapy/chemotherapy of cancer, provided that (part of) the tumor cells have been transduced by the viral (HSV-1, VZV) TK gene.

Expression of transthyretin gene in Pichia pastoris

Plasmid pSK-TTR was digested by BamHI and the DNA fragment containing Transthyretin gene was cloned into the BamHI site of vector pHIL-SI. The recombinant plasmid pHIL-SI-TTR was digested by BglII; the larger fragment was transformed into yeast Pichia pastoris. SDS-PAGE analysis showed that the yeast transformant can express and secrete TTR as a fusion protein, TTRF. To purify TTRF,the DEAE-Sepherose F.F. chromatography and Sephacryl S-200 chromatography were used. The in vitro test showed that TTRF could inhibit the growth of human hepatoma cells.

Anti-herpesvirus activity of (1'S,2'R)-9-[[1',2'-bis(hydroxymethyl)-cycloprop-1'-yl]methyl] x guanine (A-5021) in vitro and in vivo

The novel nucleoside analog (1S',2R')-9-[[1',2'-bis(hydroxymethyl)cycloprop-1-yl]methyl]guanine (A-5021) was previously shown to be a potent inhibitor of the replication of herpes simplex virus type 1 and 2 (HSV-1 and HSV-2) and varicella zoster virus (VZV), both in vitro and in vivo (J. Med. Chem. 41, 1284-1298; Antimicrob. Agents Chemother. 42, 1666-1670). Here we demonstrate that A-5021 is also a potent inhibitor of Epstein-Barr virus (EBV) and human herpes virus 6 (HHV-6A and HHV-6B), but that the compound lacks activity against HHV-8. A-5021, in comparison to acyclovir, was also assessed for protective activity against HSV-1-induced mortality in SCID mice. The compounds were administered at 50 mg/kg per day by subcutaneous injection for four consecutive days and treatment was initiated at either 2 h, 1 or 2 days post infection (p.i.). When administered from day 0 to 4 p.i., A-5021 conferred complete protection against the infection (as assessed at 22 days p.i.), whereas acyclovir delayed virus induced mortality by only 5 days. When treatment was begun on day 1 or 2, A-5021 still afforded marked protection against the infection, whereas acyclovir was virtually devoid of any activity under these conditions. Our data underline that A-5021 may offer great promise for the treatment of herpesvirus infections.

Progesterone receptor gene expression in preimplantation pig embryos

OBJECTIVE

It is not known whether progesterone, which plays a key role in establishing and maintaining pregnancy, acts directly on embryos or indirectly through the mother's reproductive tract. Since the physiological effects of progesterone are mediated by progesterone receptors (PR), the expression of PR during the preimplantation stages of pig embryos was determined.

DESIGN AND METHODS

Preimplantation pig embryos at different developmental stages were examined using reverse transcription-polymerase chain reaction techniques for the purpose of determining PR gene expression. Immunocytochemistry procedures were used to determine whether PR mRNA is translated into PR protein in preimplantation embryos.

RESULTS

PR mRNA was found in pig embryos at the two-cell stage, but levels started to decline at the four-cell stage; none was detected at the five- to eight-cell stage, nor at any time during the morula and blastocyst stages. Results showed that PR protein was immunostained in pig oocytes and embryos at the 4-cell stage, but that no significant immunostaining occurred during the morula and blastocyst stages.

CONCLUSION

These results indicate that the effects of PR on early embryogenesis appear to be indirect, perhaps via PR-regulated growth-promoting factors produced in the maternal reproductive tract.

Ribavirin and mycophenolic acid potentiate the activity of guanine- and diaminopurine-based nucleoside analogues against hepatitis B virus

Mycophenolic acid [the active metabolite of the immunosuppressive agent mycophenolate mofetil (MMF)] and ribavirin were found to potentiate the anti-HBV activity of the guanine-based nucleoside analogues penciclovir (PCV), lobucavir (LBV) and 3'-fluorodideoxyguanosine (FLG) and diaminopurine dioxolane (DAPD). Ribavirin and mycophenolic acid are both inhibitors of inosine 5'-monophosphate dehydrogenase and cause a depletion of intracellular dGTP levels. It may be assumed that the 5'-triphosphorylated derivatives of the guanine-based nucleoside analogues, in the presence of reduced levels of dGTP, inhibit more efficiently the priming reaction as well as the reverse transcription and DNA-dependent DNA polymerase activity of the HBV polymerase. This assumption is corroborated by the observation that exogenously added guanosine reversed the potentiating effect of ribavirin and mycophenolic acid on the anti-HBV activity of the guanosine analogues. Our observations may have implications for those (liver) transplant recipients that receive MMF as (part of their) immunosuppressive regimen and that, because of de novo or persistent infection with HBV, need specific anti-HBV therapy.

Estrogen-modulated estrogen receptor x Pit-1 protein complex formation and prolactin gene activation require novel protein synthesis

Both estrogen receptor (ER) and Pit-1 proteins are essential for the estrogen-activated expression of the rat prolactin gene. Our results show that ER.Pit-1 protein complex formation is reduced by estrogen in GH3 and PR1 rat pituitary tumor cells. In the latter, this decrease was blocked by cycloheximide, a protein synthesis inhibitor. On the other hand, the direct addition of estrogen to PR1 cell lysates had no effect on the formation of ER.Pit-1 complexes. Estrogen-activated prolactin gene expression was also inhibited by cycloheximide, suggesting that some form of protein synthesis is involved in ER.Pit-1 complex formation and subsequent prolactin gene activation. In support of this notion, we showed that estrogen-induced regulation of ER.Pit-1 complex formation could be transferred from cell lysates prepared from estrogen-treated PR1 cells to control cell lysates. This is not true for GH3 cells; instead, direct administration of estrogen to GH3 cell lysates readily abolished ER.Pit-1 protein complex formation in a dose-dependent manner, and such estrogen-induced regulation was blocked by the antiestrogen ICI 182,780. These findings thus indicate that 1) interaction between ER and Pit-1 proteins is estrogen-regulated in ways specific to different cell types, and 2) auxiliary protein factor synthesis may be involved in this process.

Multistate outbreak of hemolysis in hemodialysis patients traced to faulty blood tubing sets

BACKGROUND

Hemolysis associated with hemodialysis is rare. The most frequent causes of hemodialysis-associated hemolysis are chemical contamination, heat, or mechanical injury of erythrocytes from occluded or kinked hemodialysis blood lines. When patients in three states developed hemolysis while undergoing hemodialysis between May 13 and 23, 1998, an investigation was initiated.

METHODS

A case-patient was defined as any patient at healthcare facilities A (Nebraska), B (Maryland), or C (Massachusetts) during May 13 through 23, 1998 (epidemic period), who had hemolysis diagnosed > or =48 hours after undergoing hemodialysis. To identify case-patients and to determine background rates, the medical records of patients from facilities A, B, and C who were undergoing hemodialysis during the epidemic and pre-epidemic (that is, May 5 through 19, 1998) periods were reviewed. Experiments simulating hemodialysis with the same lot numbers of hemodialysis blood tubing cartridge sets used on case- and control-patients were conducted.

RESULTS

The rates of hemolysis among patients at facilities A, B, and C were significantly higher during the epidemic than the pre-epidemic period (13 out of 118 vs. 0 out of 118, P < 0.001; 12 out of 298 vs. 0 out of 298, P = 0.001; and 5 out of 62 vs. 0/65, P = 0.03, respectively). All case-patients had hemolysis. Twenty (66%) had hypertension. Eighteen (60%) had abdominal pain, and 10 (36%) were admitted to an intensive care unit. There were two deaths. The only commonality among the three outbreaks was the use of the same lot of disposable hemodialysis blood tubing from one manufacturer. Examination of the implicated hemodialysis blood tubing cartridge sets revealed narrowing of an aperture through which blood was pumped before entering the dialyzers. In vitro experiments with the hemodialysis blood tubing revealed that hemolysis was caused by increased pressure on erythrocytes as they passed through the partially occluded hemodialysis blood tubing.

CONCLUSIONS

Our investigation traced the multiple hemolysis outbreaks to partially occluded hemodialysis blood tubing produced by a single manufacturer. On May 25, 1998, the manufacturer issued a voluntary nationwide recall of the implicated lots of hemodialysis blood tubing cartridge sets.

Inhibition of the replication of the DNA polymerase M550V mutation variant of human hepatitis B virus by adefovir, tenofovir, L-FMAU, DAPD, penciclovir and lobucavir

Several nucleoside analogues (penciclovir, lobucavir, dioxalane guanine [DXG], 1-beta-2,6-diaminopurine dioxalane [DAPD], L-FMAU, lamivudine) and acyclic nucleoside phosphonate analogues (adefovir, tenofovir) that are in clinical use, in clinical trials or under preclinical development for the treatment of hepatitis B virus (HBV) infections, were evaluated for their inhibitory effect on the replication of a la- mivudine-resistant HBV variant containing the methionine --> valine substitution (M550V) in the polymerase nucleoside-binding domain. The antiviral activity was determined in the tetracycline-responsive HepAD38 and HepAD79 cells, which are stably transfected with either a cDNA copy of the wild-type pregenomic RNA or with cDNA containing the M550V mutation. As expected, lamivudine was much less ( approximately 200-fold) effective at inhibiting replication of the M550V mutant virus than the wild-type virus. In contrast, adefovir, tenofovir, lobucavir, L-FMAU, DXG and DAPD proved almost equally effective against both viruses. A second objective of this study was to directly compare the antiviral potency of the anti-HBV agents in HepG2 2.2.15 cells (which are routinely used for anti-HBV drug-screening purposes) with that in HepAD38 cells. HepAD38 cells produce much larger quantities of HBV than HepG2 2.2.15 cells, and thus allow drug screening in a multiwell plate format. All compounds were found to be almost equally effective at inhibiting HBV replication in HepAD38 cells (as in HepG2 2.2.15 cells), except for penciclovir, which was clearly less effective in HepAD38 cells.

Potential involvement of tumor suppressor gene expression in the formation of estrogen-inducible pituitary tumors in rats

While pituitary tumors can be induced in rats by the administration of estrogen, susceptibility to such tumors is highly strain dependent. In this study, 21-day-old male rats of two strains-Fischer 344 (F344) strain, which is particularly susceptible to pituitary tumors, and Sprague-Dawley (SD) strain, which is relatively resistant, were treated with diethylstilbestrol (DES) over a period of 10 days. Reverse-transcriptase polymerase chain reaction (RT-PCR) was used to analyze the expression levels of two tumor suppressor genes, p53 and rb, in the pituitaries. In SD rats, both p53 and rb mRNA appeared to increase in response to DES treatment, while in F344 rats they remained undetectable. Western blot analysis revealed that protein levels of cyclin D, which is a cell cycle regulating protein thought to be a potential oncogene, decreased in response to DES treatment in F344 rats but remained constant in SD rats. The observed differences in the expression levels of p53, rb and cyclin D suggest that they might be involved in the primary process of estrogen-induced pituitary tumor development prior to detectable tumor growth.

Lamivudine, adefovir and tenofovir exhibit long-lasting anti-hepatitis B virus activity in cell culture

In this work, we investigated the anti-hepatitis B virus (HBV) activity of lamivudine, adefovir, tenofovir, penciclovir and lobucavir after short-term (i.e. 24 or 48 h) or continuous (9 days) exposure of the HBV-containing cell line, HepG2 2.2.15, to these drugs. Lamivudine maintained significant anti-HBV activity when added for only 24 or 48 h to the cell cultures compared to when the drug was present for the whole period (9 days) on the cells, i.e. 50% effective concentration (EC50) values for the inhibition of HBV DNA synthesis were 0.07 +/- 0.02 microgram ml-1 after 24 h of incubation, 0.02 +/- 0.01 microgram ml(-1) after 48 h of incubation and 0.0016 +/- 0.001 microgram ml(-1) after 9 days of incubation. Similarly, the nucleoside phosphonate analogues, adefovir and tenofovir, retained significant anti-HBV activity when added for only a short period of time to the cells. The EC50 values were 12 +/- 1 microgram ml(-1) (24 h) and 1.0 +/- 0.2 microgram ml(-1) (48 h) vs 0.003 +/- 0.001 microgram ml(-1) (9 days) for adefovir, and 6.5 +/- 1.1 microgram ml(-1) (24 h) and 0.8 +/- 0.1 microgram ml(-1) (48 h) vs 0.03 +/- 0.02 microgram ml(-1) (9 days) for tenofovir. In contrast, penciclovir and lobucavir lost most of their anti-viral activity when present on the cells for 48 h or less.

Estrogen receptor is expressed in pig embryos during preimplantation development

Although estrogen is recognized as essential for embryonic development and maintenance of pregnancy, it remains unclear whether it has a direct role in the embryos themselves. The aim of this study was to investigate whether estrogen can have any effect in pig embryos during preimplantation development. Since the function of estrogen is mediated through its specific receptor, estrogen receptor (ER), the presence of ER mRNA and protein in pig embryos collected in vivo at different stages of preimplantation development was determined and compared. Using reverse transcription polymerase chain reaction, ER RNA was detected at the one-cell, two-cell, and four-cell stages. The level became undetectable at the five- to eight-cell stages and the morula stages and then reappeared again at the blastocyst stage. To determine whether the ER message observed in the embryos was translated into ER protein, immunocytochemical analysis was performed and the presence of ER protein was detected in oocytes at one-cell and four-cell stages. However, the amount of ER protein in porcine embryos at the blastocyst stage was still below the detection limit. The presence of ER mRNA at the blastocyst stages suggests that estrogen may start to act directly on pig embryos afterwards, and our results provide a basis for determining the direct role of estrogen in preimplantation pig embryos.

Regulation of inducible nitric oxide synthase by dietary phytoestrogen in MCF-7 human mammary cancer cells

We examined the effects of the phytoestrogen biochanin A on the growth of the MCF-7 human breast cancer cell line. The results showed that biochanin A treatment induced dose- and time-dependent inhibition on MCF-7 cell growth at concentrations above 20 microg x mL(-1). An examination of treated MCF-7 cell morphology revealed condensation of the chromosome and dehydration of the cytoplasm, suggesting apoptosis as an important factor in biochanin A-related cell growth inhibition. The results also showed that at a concentration of 40 microg x mL(-1), biochanin A decreased the levels of inducible nitric oxide synthase, thus inhibiting the production of nitric oxide, a known second messenger and inducer of apoptosis, and affecting the overall cell protein pattern. No significant difference in superoxide dismutase protein levels were, however detected at concentrations of 40 or 100 microg x mL(-1) of biochanin A. The data suggest that the inhibitory effects of biochanin A on human breast cancer cell growth are linked to inducible nitric oxide synthase and the associated production of nitric oxide.

Use of digoxigenin-labelled probes for the quantitation of HBV-DNA in antiviral drug evaluation

The use of digoxigenin-labelled probes was studied for quantitation of HBV-DNA during antiviral drug evaluation. Digoxigenin (dig)-labelled probes were generated either via incorporation of dig-dUTP in a polymerase chain reaction (PCR) or a random priming reaction. Using the PCR-labelled probe (delineating a 523 bp fragment in the core gene of the HBV) as little as 1 pg of immobilized HBV-DNA could be detected following an 8 h exposure of the hybridized membrane. A close correlation (r = 0.95) was found between the amount of HBV-DNA (range 2.5-200 pg) and the signal generated by the probe hybridized to its target DNA. By using a probe that was labelled with digoxigenin via random priming, the minimal quantity of immobilized HBV plasmid DNA that could be detected following an 8 h exposure was 4 pg, whereas a 32P-labelled probe, generated in parallel by random priming, allowed the detection of 16 pg of HBV plasmid DNA following a 4-day exposure. The PCR-generated digoxigenin-labelled probe proved to be useful for antiviral drug evaluation, i.e. to detect HBV-DNA in total cellular DNA from HBV-positive hepatoma cells (HepG2.2.15) that had either been treated with reference antiviral agents or left untreated. The 50% effective concentrations (EC50) that were calculated for inhibition of HBV-DNA production by lamivudine (3TC), penciclovir (PCV), lobucavir (LBV), adefovir (PMEA) and tenofovir (PMPA) were comparable to those reported in the literature. The use of digoxigenin-labelled probes thus appears to be a simple, convenient, rapid, reliable and non-radioactive method for use for anti-HBV screening. In addition, and in contrast to 32P-labelled probes, digoxigenin-labelled probes can be stored for >1 year without loss of specific activity, which makes these probes particularly attractive for large-scale antiviral drug evaluation purposes.

MyoD and Myf-5 define the specification of musculature of distinct embryonic origin

Mounting evidence supports the notion that Myf-5 and MyoD play unique roles in the development of epaxial (originating in the dorso-medial half of the somite, e.g. back muscles) and hypaxial (originating in the ventro-lateral half of the somite, e.g. limb and body wall muscles) musculature. To further understand how Myf-5 and MyoD genes cooperate during skeletal muscle specification, we examined and compared the expression pattern of MyoD-lacZ (258/2.5lacZ and MD6.0-lacZ) transgenes in wild-type, Myf-5, and MyoD mutant embryos. We found that the delayed onset of muscle differentiation in the branchial arches, tongue, limbs, and diaphragm of MyoD-/- embryos was a consequence of a reduced ability of myogenic precursor cells to progress through their normal developmental program and not because of a defect in migration of muscle progenitor cells into these regions. We also found that myogenic precursor cells for back, intercostal, and abdominal wall musculature in Myf-54-/- embryos failed to undergo normal translocation or differentiation. By contrast, the myogenic precursors of intercostal and abdominal wall musculature in MyoD-/- embryos underwent normal translocation but failed to undergo timely differentiation. In conclusion, these observations strongly support the hypothesis that Myf-5 plays a unique role in the development of muscles arising after translocation of epithelial dermamyotome cells along the medial edge of the somite to the subjacent myotome (e.g., back or epaxial muscle) and that MyoD plays a unique role in the development of muscles arising from migratory precursor cells (e.g., limb and branchial arch muscles, tongue, and diaphragm). In addition, the expression pattern of MyoD-lacZ transgenes in the intercostal and abdominal wall muscles of Myf-5-/- and MyoD-/- embryos suggests that appropriate development of these muscles is dependent on both genes and, therefore, these muscles have a dual embryonic origin (epaxial and hypaxial).

[The effect of chlamydia trachomatis infection in pregnant women on pregnant outcome and neonates]

OBJECTIVE

To determine the prevalence of chlamydia trachomatis (CT) in pregnant women and its effect on pregnant outcome and neonate.

METHODS

Specimen of cervical swab were collected and detected for CT by polymerase chain reaction (PCR) method meanwhile relevant factors were investigated. Pregnant outcome and neonatal situation were also followed up.

RESULTS

The infection rates of CT in pregnant women were 35.90%. The Incidence of abnormal pregnant outcome (premature delivery and abortion) was significantly higher in CT positive groups (24.72%) than that in negative groups (12.20%) (P < 0.05). Incidence of neonatal conjunctivitis and pneumonia were significantly higher in CT positive groups (17.98%) than that of negative groups (0.61%) (P < 0.01). There was statistically significant difference in the prevalence of low birth weight (< 2,500 g) between the two groups (13.48% versus 4.88%) (P < 0.05), and mode of delivery also had influence on neonatal morbidity.

CONCLUSION

Prevalence of CT infection in pregnant women is rather common, and it may cause adverse pregnancy outcome.

Myogenic determination occurs independently in somites and limb buds

Gene targeting has indicated that the bHLH transcription factors Myf-5 and MyoD are required for myogenic determination because skeletal myoblasts and myofibers are entirely ablated in mouse embryos lacking both Myf-5 and MyoD. Entrance into the skeletal myogenic program during development occurs following the independent transcriptional induction of either Myf-5 or MyoD. To identify sequences required for the de novo induction of MyoD transcription during development, we investigated the expression patterns of MyoD-lacZ transgenes in embryos deficient in both Myf-5 and MyoD. We observed that a 258-bp fragment containing the core of the -20-kb MyoD enhancer activated expression in newly formed somites and limb buds in compound mutant embryos lacking both Myf-5 and MyoD. Importantly, Myf-5- and MyoD-deficient presumptive muscle precursor cells expressing beta-galactosidase were observed to assume nonmuscle fates primarily as precartilage primordia in the trunk and the limbs, suggesting that these cells were multipotential. Therefore, cells are recruited into the MyoD-dependent myogenic lineage through activation of the -20-kb MyoD enhancer and this occurs independently in somites and limb buds.

Interaction between estrogen receptor and Pit-1 protein is influenced by estrogen in pituitary cells

The estrogen responsiveness of the rat prolactin gene expression requires the presence of both the estrogen receptor (ER) and the tissue-specific transcription factor, Pit-1 protein. We performed protein interaction assays using anti-rat Pit-1 antiserum (a-rPit-1) to investigate the physical interactions which occur between ER and Pit-1 proteins following estrogen treatment. After fusing maltose binding protein (MBP) and Pit-1 protein, we used the resulting MBP Pit-1 fusion protein to prepare a-rPit-1. Our results show that the estrogen receptor readily co-precipitated with the Pit-1 protein drawn from the lysates of two prolactin-expressing pituitary cell lines GH3 and PR1. The rate of precipitation appears to be both estrogen- and time-dependent. Cellular levels of estrogen receptors and Pit-1 proteins did not show significant changes during the time of estrogen treatment. We therefore suggest that an estrogen-dependent physical interaction between ER and Pit-1 protein exists in vivo, and that this interaction may play an important role in the regulation of prolactin gene expression.

Differential display screening for specific gene expression induced by dietary nonsteroidal estrogen

The dietary phytoestrogen, daidzein, produced a biphasic response in cell proliferation of cultured, estrogen-responsive human breast carcinoma MCF-7 cells. Cell growth was stimulated at a daidzein concentration of 0.25 microg/ml whereas the addition of daidzein at concentrations >25 microg/ml significantly inhibited cell growth in a dose-dependent fashion, resulting in an IC50 value of 50 microg/ml. Upon exposure to 50 microg/ml of daidzein, cell morphology was severely altered, cell volume decreased, and condensation of the chromosomes was clearly noticeable. To identify genes whose expression were inhibited by daidzein, a differential display reverse transcriptase polymerase chain reaction assay (DD-RT-PCR) was performed and the cDNA fragments of several daidzein-regulated genes were visualized. The sequence of one of the cloned cDNA fragments that showed differential mRNA expression level in response to daidzein at a concentration of 50 microg/ml had a high homology with a cDNA expressed in fetal human brain, EST 06411.

Severe cardiomyopathy in mice lacking dystrophin and MyoD

The mdx mouse, a mouse model of Duchenne muscular dystrophy, carries a loss-of-function mutation in dystrophin, a component of the membrane-associated dystrophin-glycoprotein complex. Unlike humans, mdx mice rarely display cardiac abnormalities and exhibit dystrophic changes only in a small number of heavily used skeletal muscle groups. By contrast, mdx:MyoD-/- mice lacking dystrophin and the skeletal muscle-specific bHLH transcription factor MyoD display a severe skeletal myopathy leading to widespread dystrophic changes in skeletal muscle and premature death around 1 year of age. The severely increased phenotype of mdx:MyoD-/- muscle is a consequence of impaired muscle regeneration caused by enhanced satellite cell self-renewal. Here we report that mdx:MyoD-/- mice developed a severe cardiac myopathy with areas of necrosis associated with hypertrophied myocytes. Moreover, heart tissue from mdx:MyoD-/- mice exhibited constitutive activation of stress-activated signaling components, similar to in vitro models of cardiac myocyte adaptation. Taken together, these results support the hypothesis that the progression of skeletal muscle damage is a significant contributing factor leading to development of cardiomyopathy.

Strain-dependent myeloid hyperplasia, growth deficiency, and accelerated cell cycle in mice lacking the Rb-related p107 gene

To investigate the function of the Rb-related p107 gene, a null mutation in p107 was introduced into the germ line of mice and bred into a BALB/cJ genetic background. Mice lacking p107 were viable and fertile but displayed impaired growth, reaching about 50% of normal weight by 21 days of age. Mutant mice exhibited a diathetic myeloproliferative disorder characterized by ectopic myeloid hyperplasia in the spleen and liver. Embryonic p107(-/-) fibroblasts and primary myoblasts isolated from adult p107(-/-) mice displayed a striking twofold acceleration in doubling time. However, cell sort analysis indicated that the fraction of cells in G1, S, and G2 was unaltered, suggesting that the different phases of the cell cycle in p107(-/-) cells was uniformly reduced by a factor of 2. Western analysis of cyclin expression in synchronized p107(-/-) fibroblasts revealed that expression of cyclins E and A preceded that of D1. Mutant embryos expressed approximately twice the normal level of Rb, whereas p130 levels were unaltered. Lastly, mutant mice reverted to a wild-type phenotype following a single backcross with C57BL/6J mice, suggesting the existence of modifier genes that have potentially epistatic relationships with p107. Therefore, we conclude that p107 is an important player in negatively regulating the rate of progression of the cell cycle, but in a strain-dependent manner.

Strain-dependent embryonic lethality in mice lacking the retinoblastoma-related p130 gene

The retinoblastoma-related p130 protein is a member of a conserved family, consisting of Rb, p107 and p130, which are believed to play important roles in cell-cycle control and cellular differentiation. We have generated a null mutation in p130 by gene targeting and crossed the null allele into Balb/cJ and C57BL/6J strains of mice. In an enriched Balb/cJ genetic background, p130(−/−) embryos displayed arrested growth and died between embryonic days 11 and 13. Histological analysis revealed varying degrees of disorganization in neural and dermamyotomal structures. Immunohistochemistry with antibody reactive with Islet-1 indicated markedly reduced numbers of neurons in the spinal cord and dorsal root ganglia. Immunohistochemistry with antibody reactive with desmin indicated a similar reduction in the number of differentiated myocytes in the myotome. The myocardium of mutant embryos was abnormally thin and resembled an earlier staged two-chambered heart consisting of the bulbus cordis and the ventricular chamber. TUNEL analysis indicated the presence of extensive apoptosis in various tissues including the neural tube, the brain, the dermomyotome, but not the heart. Immunohistochemistry with antibody reactive with PCNA revealed increased cellular proliferation in the neural tube and the brain, and decreased proliferation in the heart. The placentas of p130(−/−) embryos did not display elevated apoptosis and were indistinguishable from wild type suggesting that the phenotype was not due to placental failure. Following a single cross with the C57BL/6 mice, p130(−/−) animals were derived that were viable and fertile. These results indicate that p130 in a Balb/cJ genetic background plays an essential role that is required for normal development. Moreover, our experiments establish that second-site modifier genes exist that have an epistatic relationship with p130.

RFLP mapping and race specificity of bacterial blight resistance genes (QTLs) in rice

By using a set of 315 recombinant inbred lines (RILs) from the cross Lemont (japonica) x Teqing (indica) and a complete linkage map with 186 well distributed RFLP markers and 3 morphological markers, a major gene (Xa4) and 10 QTLs and 9 pairs of epistasis loci conferring horizontal resistance to three strains of Xanthomonas oryxa pv oryza (Xoo) were mapped. The Teqing allele at Xa4 on chromosome 11 acts as a dominant resistant gene against pathogen race CR4 and CX08, but as an additive QTL with a significantly (47%) reduced effect against the virulent strain, CR6. The major gene Xa4 exhibited stronger degree of race specificity. Most QTLs showed consistent levels of resistance against all three Xoo strains. The results suggest that a high level durable resistance to Xoo may be achieved by cumulative effects of multiple QTL.