Coronavirus pandemic derived demands and inclusive leadership on junior doctors' well-being.

BACKGROUND: International studies have revealed that numerous challenges (e.g. job demands) and opportunities (e.g. job resources as protective factors) affect the well-being of healthcare workers. AIMS: Building on the job demands-resources theory, we explored how job-related demands and the role of inclusive leadership as a job resource influenced the well-being of junior doctors during the coronavirus disease 2019 (COVID-19) pandemic. METHODS: A cross-sectional web survey was conducted in July 2022 for 82 junior doctors who had experienced the 3-year COVID-19 pandemic. The survey captured their perceived physical, psychological and COVID-19-related job demands and the inclusive leadership behaviours exhibited by their clinical unit supervisors as job resources. Data were also collected on junior doctors' experiences of burnout, compassion satisfaction and occupational commitment as variables of job outcomes. Hierarchical linear regression analysis was applied to explore the relationships between the variables. RESULTS: Physical and COVID-19-related job demands were associated with increased burnout among junior doctors. Inclusive leadership as a job resource was associated with junior doctors' reduced burnout and increased compassion satisfaction and buffered the negative effects of psychological demands on their compassion satisfaction. Only COVID-19-related job demands were associated with junior doctors' occupational commitment. CONCLUSIONS: Our study highlights the critical effects of COVID-19-related job demands on junior doctors' burnout and occupational commitment. Inclusive leadership behaviours exhibited by clinical unit supervisors are a valuable job resource, which can be incorporated as one of the competencies training for medical staff.

[Analysis of clinical characteristics and factors associated with short term outcomes in early term neonates].

Objective: To investigate the clinical characteristics of early term and full term neonates, and analyze the risk factors associated with short term outcomes in early term neonates. Method: Neonates with birth weight (BW) ≥2 500 g from year 2013 were analyzed retrospectively based on American Congress of Obstericians & Gynecologists (ACOG) latest definition of term infants. According to inclusion and exclusion criteria, early term (gestational age 37-38 weeks) and full term(gestational age 39-40 weeks) neonates were included, whose morbidity constituent proportion was analyzed by χ(2) test or Fisher accuracy test or t test or Wilcoxon test. Risk factors associated with short term outcomes in early term population were analyzed by Logistic regression analysis. Result: There were 3 002 discharged term infants being investigated, among whom 1 303 cases were included(768 males and 535 females), and 37, 38, 39 and 40 weeks' gestational age newborns were 160, 324, 450 and 369 respectively. Compared with full term neonates(n=819), early term neonates (n=484) had longer length of hospital stay (LOS)(6.0(5.0, 9.0) vs. 6.0(4.0, 8.0), Z=2.830, P=0.005), higher usage rate of intravenous antibiotics(86.4%(418/484) vs. 80.1%(656/819), χ(2)=8.009, P=0.005), higher assisted ventilation rate(9.5%(46/484) vs. 2.9%(24/819), χ(2)=25.528, P<0.01), higher pulmonary surfactant administration rate(4.3%(21/484) vs. 1.1%(9/819), χ(2)=14.006, P<0.01), as well as higher hypoglycemia incidence(3.9%(19/484) vs. 1.2%(10/819), χ(2)=10.226, P=0.001). There were no statistically significant differences in 1 min Apgar score (9(9, 10)vs. 9(9, 10), Z=0.860, P=0.390), 5 min Apgar score (10(9, 10) vs. 10(9, 10), Z=0.810, P=0.418), white blood cell count (15 (11, 21) ×10(9) /L vs.15 (11, 22) ×10(9) /L, Z=0.880, P=0.379), hemoglobin count(180 (159, 205) vs. 182 (160, 204) g/L, Z=0.560, P=0.576), or platelet count(303(234, 372) ×10(9)/L vs. 301(237, 391) ×10(9)/L, Z=0.550, P=0.584). BW between 2 500 g and 2 999 g(OR 1.69, 95% CI: 1.10-2.62, χ(2) =5.614, P=0.018), wet lung(OR=2.61, 95% CI: 1.61-4.24, χ(2)=15.023, P=0.000)and pneumonia(OR 1.88, 95% CI: 1.14-3.08, χ(2)=6.192, P=0.013) were risk factors in early term neonates' short term adverse outcomes. Conclusion: Early term newborns are still at their "immature" state, and respiratory disorders are major risk factors associated with short term outcomes. Hence, early delivery during 37-38 weeks should be avoided as possible as we can.

[Relationship of clinicopathological features and chemotherapeutic outcomes in women with BRCA1 and BRCA2 mutation-negative familial breast cancer].

OBJECTIVE: To explore the relationship of clinicopathological features and response to neoadjuvant chemotherapy in women with BRCA1 and BRCA2 mutation-negative familial breast cancer. METHODS: A total of 6 200 women with breast cancer were treated at our hospital from October 2003 to December 2012. All subjects underwent genetic testing for BRCA1 and BRCA2 genes. Patients with BRCA1 and BRCA2 mutations were excluded. This cohort of 5 842 patients with BRCA1 and BRCA2 mutation-negative breast cancer was classified as two groups: familial breast cancer patients (n=480) and sporadic breast cancer patients (n=5 362). The clinicalpathological data and response to neoadjuvant chemotherapy of the 480 patients with BRCA1 and BRCA2 mutation-negative familial breast cancer and the 5 362 patients with BRCA1 and BRCA2 mutation-negative sporadic breast cancer were compared retrospectively. Then the influencing factors of response to neoadjuvant chemotherapy were analyzed. RESULTS: Among the BRCA1 and BRCA2 mutation-negative breast cancer patients, 4.4% of the patients were diagnosed before 30 years of age in the familial breast cancer group, significantly higher than that of 2.6% in the sporadic breast cancer group(P=0.020). 5.0% of the patients in the familial breast cancer group had bilateral breast cancer, significantly higher than that of 2.7% in the sporadic breast cancer group (P=0.004). Compared with BRCA1 and BRCA2 mutation-negative sporadic breast cancer patients, the relative risk of early-onset breast cancer (≤ 30 years) and bilateral breast cancer were 1.73 and 1.91, respectively, significantly higher than that in the BRCA1 and BRCA2 mutation-negative familial breast cancer cases (P=0.020 and P=0.004). 2 964 patients in this cohort of 5 842 case sreceived neoadjuvant chemotherapy.The pathologic complete response (pCR) rate was significantly higher in the BRCA1 and BRCA2 mutation-negative familial breast cancer group than in the BRCA1 and BRCA2 mutation-negative sporadic breast cancer group (21.7% vs. 14.0%, P=0.001). Independent factors associated with pCR in BRCA1 and BRCA2 mutation-negative breast cancer patients were tumor size less than 2 cm (P=0.012), histologic grade Ⅲ (P<0.001), triple-negative breast cancers (P<0.001), and BRCA1 and BRCA2 mutation-negative familial breast cancer(P=0.001). CONCLUSIONS: Compared with BRCA1 and BRCA2 mutation-negative sporadic breast cancer, BRCA1 and BRCA2 mutation-negative familial breast cancer is more likely diagnosed before the age of 30 years and has a higher risk to develop bilateral breast cancer. BRCA1 and BRCA2 mutation-negative familial breast cancers are more likely to respond to neoadjuvant chemotherapy than BRCA1 and BRCA2 mutation-negative sporadic breast cancer.

Awareness of memory impairment increases the adherence to immunosuppressants in kidney transplant recipients.

OBJECTIVES: Nonadherence to immunosuppressive drugs is a concern among kidney transplantation recipients (KTRs). The adverse effects of immunosuppressive drugs can trigger nonadherence and lead to a great impact on the allograft survival. The aim of this prospective controlled study is to determine the major adverse effects of immunosuppressive drugs and their correlation with the nonadherence in kidney transplantation recipients. METHODS: All data were collected from medical and pharmacy records. We use modified Immunosuppressant Therapy Adherence Scale combined with Modified Transplant Symptom Occurrence and Symptom Distress scale to explore the relationship between symptom experience related to side effects of immunosuppressants and adherence. The risk of nonadherence was estimated by stepwise logistic regression while controlling for age, gender, education, and immunosuppressive medications. Multivariable analysis was performed using a single random effect of P < .2. RESULTS: In total, 412 KTRs completed the structured self-report instrument. The weekly pill counts were 84.2 ± 39.8. Overall, 21.4% of patients were nonadherent to immunosuppressive drugs. The most common adverse effects of immunosuppressive drugs were memory impairment (28.4%), insomnia (26.0%), gastrointestinal discomfort (21.4%), easy fatigue (22.1%), hand tremor (23.8%), and vision variation (29.1%). Multivariate analysis revealed that the adherence increased in patients with awareness of memory impairment (odds ratio 2.320, 95% confidence interval: 1.259-4.274, P = .007). There was no significant difference in the incidence of acute rejection, gender, age, and education between adherent and nonadherent patients. CONCLUSION: In summary, these results indicate a significant prevalence of nonadherence to immunosuppressive drugs in kidney transplantation recipients. Awareness of memory impairment significantly affected adherence to immunosuppressive drugs.

Contractile actin expression in torn human menisci.

The human meniscus is subject to injury that necessitates repair or removal. Many aspects of the cellular response to injury have not been well characterized. The purpose of this study was to describe the cellular distributions within the torn human meniscus. In addition to evaluating the cell density in selected regions, we investigated the cellular expression of a contractile actin isoform that has recently been found in the intact human meniscus. Included as a contemporaneous comparative group were torn human meniscal allografts. We hypothesized that a hypercellular surface zone would be found in the torn menisci, with a higher percentage of cells in this peripheral region expressing alpha-smooth muscle actin compared with other locations in the interior of the remnant. The rationale for this hypothesis was based on prior immunohistochemical investigations of the distribution of alpha-smooth muscle actin-containing cells in the torn human anterior cruciate ligament. Eighteen torn meniscal specimens were obtained from 17 patients, 0.5 to 84 months after injury, and four torn allograft meniscal samples were retrieved from three patients, 11 to 49 months after implantation. Microtomed sections of paraffin-embedded tissue were stained with hematoxylin and eosin and a monoclonal antibody to alpha-smooth muscle actin. The cell density and percentage of cells containing alpha-smooth muscle actin were determined in the following zones: synovial, vascular, hypercellular with loose collagen, hypocellular with dense collagen, and organized collagen. A cellular layer that resembled synovium was present on the surface of all but two of the specimens. Vascular regions were often continuous with the synovium abutting the more interior loose collagen zones. The total cell density was greatest in each of the zones closest to the periphery (synovium, vascular, and loose collagen; p < 0.001), when compared to the interior of the tissue. The synovium-like layer was found to have the highest percentage of alpha-smooth muscle actin-expressing cells and the highest alpha-smooth muscle actin-containing cell density (p < 0.05). Similar results were found for the torn allograft menisci. These findings confirm the working hypothesis and suggest that the torn human meniscus is capable of mounting a reparative response, including the proliferation of cells capable of contributing to wound closure. This underscores the importance of providing a bridging scaffold into which such cells can migrate.

Sex change in the protandrous black porgy, Acanthopagrus schlegeli: a review in gonadal development, estradiol, estrogen receptor, aromatase activity and gonadotropin.

Black porgy, Acanthopagrus schlegeli Bleeker, a marine protandrous hermaphrodite, is functional male for the first two years of life but begins to sexually change to female after the third year. Testicular tissue and ovarian tissue was separated by connective tissue in the bisexual gonad. This sex pattern provides a very good model to study the endocrine mechanism of sex change in fish. The annual profiles of plasma estradiol, vitellogenin and 11-ketotestosterone concentrations in males were significantly different from those in the three-year-old females. Significantly high levels of plasma estradiol during the prespawning/spawning season and low levels of plasma 11-ketotestosterone during the spawning season were observed in the inversing females. No difference of plasma testosterone levels was observed in males and females. Oral administration of estradiol stimulated high levels of gonadal aromatase activity, plasma gonadotropin II levels and sex change in the two-year-old fish. Exogenous estradiol administered for 5-6 months induced a reversible sex change in one- and two-year-old fish. The sensitive period for estradiol treatment of sex change is from early prespawning to spawning season. Implantation with testosterone for more than a year could not block the natural sex change in three-year-old fish. Exogenous aromatase inhibitors (1,4,6-androstatriene-3,17-dione or fadrozole) suppressed aromatase activity in the brain. Oral administration with aromatase inhibitors for a year further inhibited the natural sex change in three-year-old black porgy and all fish became functional male with spermiation. Estrogen receptor alpha gene in the ovarian tissue of bisexual gonad is significantly less expressed than that in the vitellogenic ovary of female on the basis of reverse-transcription polymerase-chain reaction. There was no difference in the annual profiles of the plasma gonadotropin II levels in the males and natural inversing females. Plasma gonadotropin II levels were significantly higher in estradiol-treated group than those in the control. It is concluded that estradiol, aromatase activity and estrogen receptor in the ovarian tissue play an important role in the natural and controlled sex change in black porgy. The association of gonadotropin and sex change in black porgy is not clear.

Integration and the performance of healthcare networks: do integration strategies enhance efficiency, profitability, and image?

PURPOSE: This study examines the integration effects on efficiency and financial viability of the top 100 integrated healthcare networks (IHNs) in the United States. THEORY: A contingency-strategic theory is used to identify the relationship of IHNs' performance to their structural and operational characteristics and integration strategies. METHODS: The lists of the top 100 IHNs ranked in two years, 1998 and 1999, by the SMG Marketing Group were merged to create a database for the study. Multiple indicators were used to examine the relationship between IHNs' characteristics and their performance in efficiency and financial viability. A path analytical model was developed and validated by the Mplus statistical program. Factors influencing the top 100 IHNs' images, represented by attaining ranking among the top 100 in two consecutive years, were analysed. RESULTS AND CONCLUSION: No positive associations were found between integration and network performance in efficiency or profits. Longitudinal data are needed to investigate the effect of integration on healthcare networks' financial performance.

The hinge of the human papillomavirus type 11 E2 protein contains major determinants for nuclear localization and nuclear matrix association.

The E2 protein of papillomaviruses is a site-specific DNA binding nuclear protein. It functions as the primary replication origin recognition protein and assists in the assembly of the preinitiation complex. It also helps regulate transcription from the native viral promoter. The E2 protein consists of an amino-terminal (N) trans-acting domain, a central hinge (H) domain, and a carboxyl-terminal (C) protein dimerization and DNA binding domain. The hinge is highly divergent among papillomaviruses, and little is known about its functions. We fused the enhanced green fluorescent protein (GFP) with the full-length human papillomavirus type 11 (HPV-11) E2 protein and showed that the resultant fusion, called gfpE2, maintained transcription and replication functions of the wild-type protein and formed similar subnuclear foci. Using a series of GFP fusion proteins, we showed that the hinge conferred strong nuclear localization, whereas the N or C domain was present in both cytoplasm and nucleus. Biochemical fractionation demonstrated that the N domain and hinge, but not the C domain, independently associated with the nuclear matrix. Mutational analyses showed that a cluster of basic amino acid residues, which is conserved among many mucosotropic papillomaviruses, was required for efficient nuclear localization and nuclear matrix association. This mutation no longer repressed the HPV-11 upstream regulatory region-controlled reporter expression. However, a very small fraction of this mutant colocalized with E1 in the nucleus, perhaps by a piggyback mechanism, and was able to support transient replication. We propose that the hinge is critical for the diverse regulatory functions of the HPV-11 E2 protein during mRNA transcription and viral DNA replication.

HeLa cells are phenotypically limiting in cyclin E/CDK2 for efficient human papillomavirus DNA replication.

Human papillomaviral (HPV) origin-containing plasmids replicate efficiently in human 293 cells or cell extracts in the presence of HPV origin-recognition protein E2 and replication initiation protein E1, whereas cervical carcinoma-derived, HPV-18-positive HeLa cells or cell extracts support HPV DNA replication poorly. We recently showed that HPV-11 E1 interacts with cyclin/cyclin-dependent kinase (cdk) complexes through an RXL motif and is a substrate for these kinases. E1 mutations in this motif or in candidate cdk phosphorylation sites are impaired in replication, suggesting a role for cdks in HPV replication. We now demonstrate that one limiting activity in HeLa cells is cyclin E/CDK2. Purified cyclin E/CDK2 or cyclin E/CDK3 complex, but not other cdks, partially complemented HeLa cell extracts. Cyclin E/CDK2 expression vectors also enhanced transient HPV replication in HeLa cells. HeLa cell-derived HPV-18 E1 protein is truncated at the carboxyl terminus but can associate with cyclin E/CDK2. This truncated E1 was replication-incompetent and inhibited cell-free HPV replication. These results indicate that HeLa cells are phenotypically limiting in cyclin E/CDK2 for efficient HPV replication, most likely due to sequestration by the endogenous, defective HPV-18 E1 protein. Further analyses of the regulation of HPV E1 and HPV replication by cyclin E may shed light on the roles of cyclin E/CDK2 in cellular DNA replication.

A defective RNA associated with bamboo mosaic virus and the possible common mechanisms for RNA recombination in potexviruses.

A naturally occurring 1.1 kb RNA was isolated from purified virions of bamboo mosaic potexvirus isolate S (BaMV-S). This RNA is a defective RNA (D RNA) derived from a single internal deletion of the BaMV genome. A cDNA clone representing the complete nucleotide sequence of the BaMV-S D RNA was generated and its nucleotide sequence was determined. The BaMV D cDNA is 1015 nts in length [excluding the poly(A) tail] and consists of two regions corresponding to 867 nts of the 5' terminus and 148 nts of the 3' terminus of the BaMV genomic RNA. BaMV D cDNA contains a single open reading frame (ORF) encoding a putative 29.7 kDa protein comprised of a fusion of the first 258 amino acids of BaMV ORF 1 and the last 2 amino acids of coat protein. The coding capacity of D RNA was verified by in vitro translation of native BaMV-S D RNA and of 1.1 kb RNA transcribed in vitro from the full-length D cDNA. BaMV D RNA can be reproducibly generated by serial passages of BaMV-S in Nicotiana benthamiana and is the first D RNA in the potexvirus group shown to be generated de novo. Alignments of sequences surrounding the 5' and 3' junction borders of reported potexvirus D RNAs reveal a 65.2-84.6% sequence identity, suggesting that common mechanisms for viral RNA recombination are involved in the generation of potexvirus D RNAs.

Sufficient length of a poly(A) tail for the formation of a potential pseudoknot is required for efficient replication of bamboo mosaic potexvirus RNA.

RNAs transcribed from a full-length infectious cDNA clone of the bamboo mosaic potexvirus (strain O) genome, pBaMV-O, were infectious to Nicotiana benthamiana plants. Mutant genomes in which the poly(A) tail is absent or replaced by a 3' tRNA-like structure from turnip yellow mosaic virus RNA failed to amplify detectably in N. benthamiana protoplasts. No amplification was detected in protoplasts inoculated with transcripts containing 4, 7, or 10 adenylate residues at the 3' end, whereas transcript inocula with 15 adenylate residues resulted in coat protein accumulation to a level 26% of that resulting from inoculation with transcripts with 25 adenylate residues (designated as wild type). Coat protein accumulation levels of 69 and 98% relative to wild type were observed after inoculation of protoplasts with transcripts bearing poly(A) tails 18 and 22 nucleotides long, respectively. The presence of a putative 3' pseudoknot structure including at least 13 adenylate residues of the 3'-terminal poly(A) tail was supported by enzymatic and chemical structural analysis. The functional relevance of this putative pseudoknot was tested by mutations that affected basepairing within the pseudoknot. These results support the existence of functional 3' pseudoknot that includes part of the 3' poly(A) tail.

Interaction between cyclin-dependent kinases and human papillomavirus replication-initiation protein E1 is required for efficient viral replication.

We have identified the human papillomavirus (HPV) DNA replication initiation protein E1 as a tight-binding substrate of cyclin E/cyclin-dependent kinase (Cdk) complexes by using expression cloning. E1, a DNA helicase, collaborates with the HPV E2 protein in ori-dependent replication. E1 formed complexes with cyclin E in insect and mammalian cells, independent of Cdks and E2. Additional cyclins, including A-, B-, and F-type (but not D-type), interacted with the E1/E2 complex, and A- and E-type cyclin kinases were capable of phosphorylating E1 and E2 in vitro. Association with cyclins and efficient phosphorylation of E1 required the presence of a cyclin interaction motif (the RXL motif). E1 lacking the RXL motif displayed defects in E2-dependent HPV ori replication in vivo. Consistent with a role for Cdk-mediated phosphorylation in E1 function, an E1 protein lacking all four candidate Cdk phosphorylation sites still associated with E2 and cyclin E but was impaired in HPV replication in vitro and in vivo. Our data reveal a link between cyclin/Cdk function and activation of HPV DNA replication through targeting of Cdk complexes to the E1 replication-initiation protein and suggest a functional role for E1 phosphorylation by Cdks. The use of cyclin-binding RXL motifs is now emerging as a major mechanism by which cyclins are targeted to key substrates.

Analysis of integrated healthcare networks' performance: a contingency-strategic management perspective.

Few empirical analyses have been done in the organizational researches of integrated healthcare networks (IHNs) or integrated healthcare delivery systems. Using a contingency derived contact-process-performance model, this study attempts to explore the relationships among an IHN's strategic direction, structural design, and performance. A cross-sectional analysis of 100 IHNs suggests that certain contextual factors such as market competition and network age and tax status have statistically significant effects on the implementation of an IHN's service differentiation strategy, which addresses coordination and control in the market. An IHN's service differentiation strategy is positively related to its integrated structural design, which is characterized as integration of administration, patient care, and information system across different settings. However, no evidence supports that the development of integrated structural design may benefit an IHN's performance in terms of clinical efficiency and financial viability.

Subgenomic RNAs of bamboo mosaic potexvirus-V isolate are packaged into virions.

Purified virions of bamboo mosaic potexvirus-V isolate (BaMV-V) were found to contain three major RNA species, the 6.4 kb genomic RNA and two RNAs of 2.0 and 1.0 kb, in addition to associated satellite RNA (0.85 kb). Results of Northern blot hybridization, primer extension analysis and cDNA sequencing showed that the packaged 2.0 and 1.0 kb RNAs of BaMV-V were subgenomic RNAs. In contrast, in the BaMV-O isolate, only genomic RNA was packaged and encapsidated subgenomic RNAs were not detectable. The transcription initiation sites for the 2.0 and 1.0 kb subgenomic RNAs of BaMV-V were located 1 1 and 16 nt upstream of the initiation codon of open reading frames (ORFs) 2 and 5, respectively. The 2.0 and 1.0 kb subgenomic RNAs functioned as messengers for the ORF2 protein and capsid protein, respectively. Packaging of the 1.0 kb subgenomic RNAs resulted in the formation of rod-shaped particles about 70 nm in length. Our results indicate that BaMV isolates have evolved distinctly for packaging of subgenomic RNAs.

Physical mapping of RFLP markers on four chromosome arms in maize using terminal deficiencies.

Terminal deficiencies (TDs) generated by the r-X1 deletion system in maize were used to physically map RFLP markers on the short arm of chromosome 2 (2S) and the long arm of chromosome 6 (6L), chromosome 8 (8L), and chromosome 10 (10L). Five TDs on 2S, 8 on 6L, 10 on 8L, and 20 on 10L were isolated using the recessive morphological markers lg1, py1, j1(gl18), and sr2, respectively, for selection. Two exceptional TDs on 2S and 8L also have a second breakpoint on the long arm of chromosome 2 (2L) and 8L, respectively. The physical mapping of RFLP probes in relation to TD breakpoints was done by Southern hybridization. The five TDs on 2S divide chromosome 2 into four regions, all of which are distinguishable by RFLP markers. Likewise, three remaining chromosome arms are divided by TDs into RFLP-marked regions: 8 TDs divide 6L into five regions, 10 TDs divided 8L into seven regions, and 20 TDs divide 10L into three regions. The linear order of the physical map of 6L and 8L is consistent with that of the genetic maps, but that of 2L and 10L is not. Four groups of markers on 2S as well as 2L, and two on 10L are in reverse order in the physical map compared with the genetic maps. Other intriguing results are that breakpoints of TDs on 6L and 8L are distributed throughout the selected region, but most of those on 2L and 10L cluster in a region near the centromere: a single TD arose after fertilization.

Prostaglandin E2 (PGE2) and risedronate was superior to PGE2 alone in maintaining newly added bone in the cortical bone site after withdrawal in older intact rats.

The objects of this study were (1) to determine the effects of risedronate (Ris) and prostaglandin E2 (PGE2) alone and in combination, on tibial diaphyses of older intact female rats; and (2) to observe the fate of any extra bone if formed after withdrawal of the treatment. Nine-month-old female Sprague-Dawley rats were treated with 6 mg of PGE2/kg/day, 1 or 5 micrograms of Ris/kg twice a week, or 6 mg of PGE2/kg/day plus 1 or 5 micrograms of Ris/kg twice a week for the first 60 days and followed by vehicle injections for another 60 days. Cross-sections of double fluorescent labeled, undecalcified tibial diaphyses proximal to the tibiofibular junction were processed for histomorphometry. We found that: (1) neither the 1 microgram nor the 5 micrograms of Ris treatment in the 60-day on/60-day off group showed any histomorphometric differences from age-related controls; (2) while the 60 days of PGE2 treatment added extra cortical bone (6%) on the tibial shaft (due to stimulation of periosteal, endocortical, and marrow trabecular bone formation), the new endocortical and most of the new marrow trabecular bone were lost when treatment was withdrawn; however, the new periosteal bone remained; (3) PGE2 with Ris added the same amount of new bone to tibial diaphysis as did PGE2 alone and upon withdrawal, new marrow trabecular bone was lost but new periosteal and endocortical bones were preserved in PGE2 + 1 microgram of Ris on/off group. In contrast, all the new bone was maintained in the PGE2 + 5 micrograms of Ris on/off group; (4) PGE2 + Ris cotreatment failed to block the increase in cortical bone porosity induced by PGE2; and (5) in the PGE2 alone and PGE2 + 1 microgram of Ris on/off groups bone turnover was higher than that in the PGE2 + 5 micrograms of Ris on/off group. These results indicate that on/off treatment with PGE2 and Ris is superior to PGE2 alone in that it forms the same amount of new bone during treatment, but preserves more cortical bone during withdrawal. Depression of bone resorption and turnover were the tissue mechanisms responsible for this protection.

The endocrine mechanism of sex reversal in the protandrous black porgy, Acanthopagrus schlegeli: a review.

Black porgy, Acanthopagrus schlegeli Bleeker, a marine protandrous hermaphrodite, is a functional male for the first 2 years of life but begin to sexually reverse to female after the third year. This sex pattern provides a very good model to study the mechanism of sex reversal in fish. The gonad at 5 month of age consisted of testicular tissue with few primary oocytes at 5 month of age. The ovarian tissue became dominant at 18 months of age during the non-spawning season. Testicular and ovarian tissues were separated by connective tissue. Plasma estradiol-17 beta(E2), vitellogenin and 11-ketotestosterone (11-KT) profiles in males were significantly different from those in the 3-year-old reversing females. Peak levels of plasma E2 in the reversing females occurred during the early prespawning season (in October). Lower levels of plasma E2 were, however, observed in the males. Plasma 11-KT levels significant decreased but no changes of plasma testosterone were detected in the reversing females. Exogenous E2 suppressed the testicular development but induced the gonadal aromatase activity, ovarian development and sex reversal in 2-year-old black porgy. Exogenous T and LHRH analog did not have effects on the sex reversal. Higher concentrations of pituitary GtH II and mRNA of GtH II-beta subunit were detected in the reversed females. These data suggested that E2 and gonadal aromatase closely associated to the occurrence of sex reversal. A working model of the sex reversal in black porgy is proposed.

The open reading frame of bamboo mosaic potexvirus satellite RNA is not essential for its replication and can be replaced with a bacterial gene.

A satellite RNA of 836 nt depends on the bamboo mosaic potexvirus (BaMV) for its replication and encapsulation. The BaMV satellite RNA (satBaMV) contains a single open reading frame encoding a 20-kDa nonstructural protein. A full-length infectious cDNA clone has been generated downstream of the T7 RNA polymerase promoter. To investigate the role of the 20-kDa protein encoded by satBaMV, satBaMV transcripts containing mutations in the open reading frame were tested for their ability to replicate in barley protoplasts and in Chenopodium quinoa using BaMV RNA as a helper genome. Unlike other large satellite RNAs, mutants in the open reading frame did not block their replication, suggesting that the 20-kDa protein is not essential for satBaMV replication. Precise replacement of the open reading frame with sequences encoding chloramphenicol acetyltransferase resulted in high level expression of chloramphenicol acetyltransferase in infected C. quinoa, indicating that satBaMV is potentially useful as a satellite-based expression vector.

[Quantitative study on the effect of osthole on proximal tibiae in ovariectomized (OVX) rats].

Thirty-one 3-month-old Female Sprague-Dawley rats were randomly divided into 5 groups, basal control (group 1, killed at the begining), aging control (group 2), ovariectomized (OVX, group 3), OVX with nilestriol treatment group (group 4) and OVX with osthole treatment group (group 5). Group 2 and group 3 ig with water 5 ml.kg-1 and group 5 ig with osthole 6.7 mg.kg-1, all once a day for 6 d; group 4 ig with nilestriol 1 mg.kg-1, once a week. After 12 weeks, all rats were killed. The proximal tibiae of rats were processed to undecalcified sections at 20 microns thickness for histomorphometric analysis. OVX was shown to reduce markedly the trabecular bone mass (%Tb. Ar-59%) due to increase of bone turnover with the result that bone resorption exceeded bone formation, as compared with aging controls. In contrast, treatment of OVX rats with Osthole and nilestriol increased significantly the trabecular area (increased 68% and 27.1% compared with that of OVX respectively). Our results indicate that osthole and nilestriol treatment provides protection against osteoporosis in OVX rats. The protective mechanism of osthole and nilestriol involves supression of bone turnover, but the effects of osthole is lower than that of nilestriol (trabecular area decreased 55% more in osthole group than that with nilestriol treatment). Our finding may provide theoretical evidence for the clinical use of osthole or nilestriol for treatment and prevention of osteoporosis.

Characterization of vitellogenin induced by estradiol-17ß in protandrous black porgy,Acanthopagrus schlegeli.

The objectives of this study were to isolate and characterize vitellogenin from plasma of estradiol-treated protandrous black porgy,Acanthopagrus schlegeli. Vitellogenin concentrations in plasma measured by a validated enzyme-linked immunosorbent assay (ELISA) were also compared. Two-year-old black porgy (n=20) were fed with estradiol-17ß (4 mg kg(-1) of feed). Plasma was collected for purification of vitellogenin. Two forms of vitellogenin were found in plasma after chromatography on Sepharose CL-2B column and hydroxylapatite, and polyacrylamide gel electrophoresis. Black porgy vitellogenins are phospho-lipo-glycoproteins based on their chemical staining properties. The apparent molecular weights of the two forms of vitellogenin were 636 kDa and 321 kDa, respectively. The amino acid composition of purified vitellogenin was also analyzed after acid hydrolysis. The presence of immunoreactive vitellogenin was identified in the plasma and mucus extract from control and estradiol-induced females on the basis of Western blotting. Serial dilution of the plasma and mucus extract taken from estradiol-induced black porgy showed reactivity to an antiserum against lipovitellin in the ELISA, whereas mucus extract and plasma from male fish did not. Significantly higher concentrations of plasma vitellogenin were detected in estradiol-stimulated black porgy than in the control males.