[Study on risk factors of mycobacterium tuberculosis infection among health workers in medical institutions]

Objective: To understand the infection status of mycobacterium tuberculosis among health workers in tuberculosis designated medical institutions and explore the risk factors of infection. Methods: From September 2021 to June 2022, a questionnaire survey was conducted among health workers in relevant departments of 4 tuberculosis designated medical institutions by cluster stratified sampling, including the implementation of hospital infection control measures in medical institutions and occupational exposure of medical staff to mycobacterium tuberculosis. Peripheral blood interferon gamma release assays (IGRAs) and lung imaging examination were performed to determine the mycobacterium tuberculosis infection. Factors with statistical significance in univariate analysis were included in multivariate logistic regression to analyze the risk factors of mycobacterium tuberculosis infection. Results: A total of 657 people completed the lung imaging examination and questionnaire, of which 654 people had peripheral blood IGRAs detection, and the latent infection rate of tuberculosis was 39.45% (258/654) . Univariate analysis showed that age, sex, marital status, economic income, occupational category, professional title, length of service, and other variables had statistical significances in tuberculosis latent infection (P<0.05) . In terms of personal health status, there were statistically significant differences in the distribution of health workers in terms of their tuberculosis history, tuberculosis history of their immediate family members, previous tuberculin skin test (TST) (P<0.05) . Multivariate analysis showed that there were four risk factors related to tuberculosis, including professional title (X(1)) , years of tuberculosis related works (X(2)) , tuberculosis history (X(3)) and previous TST (X(4)) . The regression equation of the probability of tuberculosis among health workers was y=-1.920+0.246X(1)+0.046X(2)+1.231X(3)+0.478X(4). Conclusion: The latent infection rate of tuberculosis among health workers in tuberculosis designated medical institutions is high. It is necessary to strengthen the management of infection control, carry out regular screening, enhance the self-protection awareness of health workers, and reduce their exposure to mycobacterium tuberculosis and infection risk.

Exorista sorbillans (Diptera: Tachinidae) parasitism shortens host larvae growth duration by regulating ecdysone and juvenile hormone titers in Bombyx mori (Lepidoptera: Bombycidae)

The tachinid fly, Exorista sorbillans, is a notorious ovolarviparous endoparasitoid of the silkworm, Bombyx mori, causing severe damage to silkworm cocoon industry. Silkworm larvae show typically precocious wandering behavior after being parasitized by E. sorbillans; however, the underlying molecular mechanism remains unexplored. Herein, we investigated the changes in the levels of 20-hydroxyecdysone (20E) and juvenile hormone (JH) titer, and they both increased in the hemolymph of parasitized silkworms. Furthermore, we verified the expression patterns of related genes, which showed an upregulation of 20E signaling and biosynthesis genes but a significant downregulation of ecdysone oxidase (EO), a 20E inactivation enzyme, in parasitized silkworms. In addition, related genes of the JH signaling were activated in parasitized silkworms, while related genes of the JH degradation pathway were suppressed, resulting in an increase in JH titer. Notably, the precocious wandering behavior of parasitized silkworms was partly recoverable by silencing the transcriptions of BmCYP302A1 or BmCYP307A1 genes. Our findings suggest that the developmental duration of silkworm post parasitism could be shortened by regulation of 20E and JH titers, which may help silkworm to resist the E. sorbillans infestation. These findings provide a basis for deeper insight into the interplay between silkworms and E. sorbillans and may serve as a reference for the development of a novel approach to control silkworm myiasis.

Hydrogen sulfide treatment retrieves the inhibition of growth and development characteristics in silkworm (Bombyx mori) via phosphoacetyl glucosamine mutase gene knock down

Phosphoacetyl glucosamine mutase (PGM) is the key gene for glycolysis of important metabolic pathways in silkworm, and H₂ S (7.5 μM) can promote the growth and development of silkworm. Herein, we used body cavity injection of small-interfering RNA (siRNA) to interfere with the PGM gene in H₂ S-treated silkworms. After RNA interference (RNAi), we investigated the growth and development of the silkworm. H₂ S treatment could significantly recover the inhibition of body weight, cocoon weight, cocoon shell weight, and cocoon shell ratio by knocking down PGM gene in silkworm, without significant effects on eggs laying and production, and then analyzed the mRNA expression of PGM gene. The interference of siRNA significantly decreased the expression of targeted PGM gene and was concentrated in 48 h followed by gradual recovery. Three interference fragments also showed different interference effects, and siRNA of PGM-3 exerted the highest interference effect to the target gene expression. Fat body had the highest mRNA expression of PGM gene, and the best interference effect was observed after siRNA injection. The results showed that the gene based on H₂ S treatment may have an important impact on the growth and development of silkworm by affecting its metabolic pathway.

Bombyx mori miR-2845 represses the expression of fibroin light chain gene both in vitro and in vivo

To study the regulatory function of Bombyx mori (B. mori) miRNAs (bmo-miR) on the expression of fibroin light chain gene (BmFib-L), the 3’UTR of BmFib-L mRNA was used as the target for online prediction of miRNAs from miRBase using RNAhybrid Software, and miR-2845 was screened out. First, the expression profiles of miR-2845 and BmFib-L in larvae of the 5th instar were analyzed by Real-time quantitative PCR (RT-qPCR). Then recombinant plasmids (pcDNA3.0-pre-miR-2845 and pGL3.0-BmFib-L) were constructed to use for the expression of miR-2845 and BmFib-L 3’UTR, respectively. Cellular-level functional verification of miR-2845 on BmFib-L was carried out using multiple experimental methods (including dual luciferase reporter vectors, artificially synthesized mimics and inhibitors, and target site mutations). Finally, in vivo functional verification was performed by injecting the recombinant vector in 5th instar larvae. BmFib-L expression levels were detected using RT-qPCR in the posterior silk glands (PSG) of the injected larvae. Results showed that the expression of miR-2845 increased between the 1^st and 5^th day in 5^th instar larvae, but began to decline on the 5^th day, while the expression of the target gene BmFib-L increased sharply. This suggests that miR-2845 and BmFib-L expression levels show opposing trends, implying a negative regulatory relationship. In BmN cells, miR-2845 significantly down-regulated the expression of BmFib-L; the inhibitory effect of miR-2845 on BmFib-L was disappeared after mutation of the targeting site on 3’UTR of BmFib-L; in individuals, miR-2845 significantly down-regulated BmFib-L expression levels. Our results provide new experimental data for clarifying the molecular regulation mechanism of silk protein expression.

Transcriptome Analysis Reveals the Gene Expression Changes in the Silkworm (Bombyx mori) in Response to Hydrogen Sulfide Exposure

Simple Summary

The fat body is one of the most important tissues in the body of insects due to its number of functions. Nowadays the new physiological function of H₂S has gained attention as a novel signaling molecule. H₂S performs crucial regulatory functions involving growth, the cardiovascular system, oxidative stress, and inflammation in many organisms. In this study, RNA-seq technology was used to investigate the fat body of the silkworm at the transcriptional level after H₂S exposure during the 5th larvae stage. A total of 1200 (DEGs) was identified after 7.5 µM H₂S treatment, of which 977 DEGs were up-regulated and 223 DEGs were down-regulated. DEGs were mainly involved in the transport pathway, cellular community, carbohydrate metabolism, and immune-associated signal transduction. Present research provides new insights on the gene expression changes in the fat body of silkworms after H₂S exposure.

Abstract

Hydrogen sulfide (H₂S) has been recognized for its beneficial influence on physiological alterations. The development (body weight) and economic characteristics (cocoon weight, cocoon shell ratio, and cocoon shell weight) of silkworms were increased after continuous 7.5 µM H₂S treatment. In the present study, gene expression changes in the fat body of silkworms at the 5th instar larvae in response to the H₂S were investigated through comparative transcriptome analysis. Moreover, the expression pattern of significant differentially expressed genes (DEGs) at the 5th instar larvae was confirmed by quantitative real-time PCR (qRT-PCR) after H₂S exposure. A total of 1200 (DEGs) was identified, of which 977 DEGs were up-regulated and 223 DEGs were down-regulated. Most of the DEGs were involved in the transport pathway, cellular community, carbohydrate metabolism, and immune-associated signal transduction. The up regulated genes under H₂S exposure were involved in endocytosis, glycolysis/gluconeogenesis, the citrate cycle (TCA cycle), and the synthesis of fibroin, while genes related to inflammation were down-regulated, indicating that H₂S could promote energy metabolism, the transport pathway, silk synthesis, and inhibit inflammation in the silkworm. In addition, the expression levels of these genes were increased or decreased in a time-dependent manner during the 5th instar larvae. These results provided insight into the effects of H₂S on silkworms at the transcriptional level and a substantial foundation for understanding H₂S function.

A 14-amino acids deletion in BmShadow results to non-moult on the 2nd instar in the bivoltine silkworm, Bombyx mori

The Bombyx mori Shadow gene (BmShadow) belongs to the superfamily of cytochrome P450 genes. To elucidate the function of the BmShadow gene and its association with diapause, we employed the CRISPR/Cas9 system to knock out the BmShadow gene in the bivoltine strain Qiufeng. The mutant (BmShadow^-/-) was obtained in G₂, exhibiting a 42-base deletion corresponded exactly to the amino acids regions from positions 155 to 168. The larvae of BmShadow^-/- cannot moult at the pre-moulting stage of the 2nd instar. When the BmShadow^-/- larvae were fed with 20E analogue at the late stage of the 2nd instar, they were rescued and developed into the 3rd instar. Rescue experiments indicated that the 20E concentration of BmShadow^-/- larvae was significantly lower than that in WT larvae, and the 20E concentration of BmShadow^-/- larvae which fed 20E analogue was restored to normal levels. Interestingly, the BmShadow^-/- larvae could not moult on the 1st instar when they hatched from eggs after being stored at 5 °C for 40 days or after hibernation, suggesting that the 20E transported from the mother was partially consumed in the diapause maintenance phase. Our study confirmed that BmShadow is involved in 20E synthesis and a 14-amino acids region from position 155 to 168 was essential for its function, also there appears to be no other compensation pathway in vivo, which offered an important potential target locus for the control of silkworm development and the biological control of agricultural and forestry pests.

Transcriptome analysis reveals gene expression changes of the fat body of silkworm (Bombyx mori L.) in response to selenium treatment

A comparative transcriptome analysis was conducted to investigate the gene expression changes in the fat body of silkworm after treatment with different concentrations (50 μM and 200 μM) of selenium (Se). 912 differential expression genes (DEGs) (371 up-regulated and 541 down-regulated) and 1420 DEGs (1078 up-regulated and 342 down-regulated) were identified in silkworm fat body treated with 50 μM and 200 μM of Se, respectively. In case of 50 μM group, DEGs were mainly enriched in the peroxisome pathway and fatty acid metabolism pathway, and later were associated with antioxidant defense and nutrition regulation. After 200 μM Se-treatment, DEGs were mainly located in the glycerolipid metabolism and arachidonic acid metabolism pathways, which further encoded detoxification related genes. Furthermore, 32 candidate DEGs from these pathways had been selected to confirm the RNA-seq data. Among these DEGs, 14 genes were up-regulated in the 50 μM Se-treated group (only three genes in the 200 μM Se-treated group) which were involved in lipid metabolism and antioxidant defense, and 13 up-regulated genes (only two genes were up-regulated in the 50 μM Se-treated group) were involved in detoxification of the 200 μM Se-treated group. These changes showed that lower concentration of Se could regulate the nutrition and promote antioxidation pathways; whereas, high levels of Se promoted the detoxification of silkworm. These findings can be helpful to understand the possible mechanisms of Se action and detoxification in silkworm and other insects.

Evaluation of the Metabolic Effects of Hydrogen Sulfide on the Development of Bombyx mori (Lepidoptera: Bombycidae), Using Liquid Chromatography-Mass Spectrometry-Based Metabolomics

Hydrogen sulfide (H2S) is a highly poisonous gas with an unpleasant smell of rotten eggs. Previous studies of H2S have primarily focused on its effects on mammalian nervous and respiratory systems. In this study, silkworm developmental parameters and changes in metabolites in response to H2S exposure were investigated using a hemolymph metabolomic approach, based on liquid chromatography-mass spectrometry (LC-MS). The developmental parameters, body weight, cocoon weight, cocoon shell weight, and cocoon shell ratio, were noticeably increased following H2S exposure, with the greatest effects observed at 7.5-μM H2S. Metabolites upregulated under H2S exposure (7.5 μM) were related to inflammation, and included (6Z, 9Z, 12Z)-octadecatrienoic acid, choline phosphate, and malic acid, while hexadecanoic acid was downregulated. Identified metabolites were involved in biological processes, including pyrimidine, purine, and fatty acid metabolism, which are likely to affect silk gland function. These results demonstrate that H2S is beneficial to silkworm development and alters metabolic pathways related to spinning function and inflammation. The present study provides new information regarding the potential functions of H2S in insects and metabolic pathways related to this phenomenon.

Effect of Dietary Selenium Supplementation on Growth and Reproduction of Silkworm Bombyx mori L

The effects of selenium (Se) on the growth and reproduction of the Lepidoptera insect, the silkworm, Bombyx mori L were investigated. Initially, the silkworms were divided into eight groups (150 larvae/group) on the basis of feeding with mulberry leaves saturated with different concentrations of Se (25, 50, 100, 125, 150, 175, and 200 μM) and control from the first day of the fourth instar larvae. After feeding, growth and reproductive performance of B. mori L. were investigated with standard techniques used in sericulture. After the data analysis, 50 μM of Se was recognized as the optimal level which positively influenced the growth and production, with prolonged stage of larvae, increased larval, cocoon, and pupal weights, and enhanced number of eggs laid by the female moth as compared to the control group. On the contrary, 200 μM of Se treatment displayed toxic to silkworm and induced significant decrease in the growth, cocoon production, and reproduction. The weight of the cocoon shell, the cocoon shell ratio, number of eggs produced, and fertilization ratio in all the Se-treated groups were lower than the control group. The present study indicated that lower levels of (50 μM) of Se can promote the larval and pupal growth of the B. mori L. resulting in the higher yield of cocoon crop and significantly influencing the fecundity, while high concentration was toxic to silkworm. Our data supply the novel application of Se which could be highly beneficial to sericulture farmers.

[Study of bone mineral density and serum bone turnover markers in newly diagnosed systemic lupus erythematosus patients]

OBJECTIVE

To investigate the changes of bone mineral density (BMD) and serum bone turnover factor in newly diagnosed systemic lupus erythematous (SLE) patients.

METHODS

Eighty newly diagnosed SLE patients and 80 age and gender matched healthy controls were enrolled. None of the SLE patients had ever received glucocorticoid, immunosuppressive agents or vitamin D. BMD was measured at radius,lumbar spine and hip by dual X ray absorptiometry (DXA). Bone turnover markers including serum levels of tartrate-resistant acid phosphatase 5b (TRAP5b),bone alkaline phosphatase (BAP) and 25-hydroxy vitamin D3 (25-OH-VD3) were measured by enzyme-linked immunosorbent assay (ELISA). Logistic regression was employed to analyze the risk factors associated with decreased BMD.

RESULTS

Mean age of the SLE patients was (32.8±12.4) years, and 85% were female, none of whom were post-menopausal. BMD was significantly reduced in all the measured sites, compared with the healthy controls. Sixteen (20%) of the patients were osteopenic in at least one site measured locations. The serum levels of 25-OH-VD3 were markedly reduced in the newly diagnosed SLE patients than those of the normal controls [(46.1+12.3) nmol/L vs. (25.4+11.2) nmol/L, P<0.001)]. The serum levels of 25-OH-VD3 in the SLE patients with nephritis were much lower than those without nephritis (P=0.04). A significant negative correlation was demonstrated between the serum concentration of 25-OH-VD3 and the disease activity scores as measured by SLE disease activity index (SLEDAI) (r=-0.3,P=0.001). The serum TRAP5b concentration was positively correlated with SLEDAI (r=0.435,P=0.003). Age (P=0.058) and SLEDAI (P=0.085) were probably associated with decreased BMD in Logistic regression analysis.

CONCLUSION

The study showed reduced BMD in untreated SLE patients. The role of chronic inflammation was of probable importance in bone metabolism.

[Comparison of bone destruction markers in patients with gouty arthritis under different musculoskeletal ultrasonic manifestations]

Objectives: To observe the correlation between the different ultrasonic manifestations of gouty arthritis and the indexes of bone destruction (Dickkopf-1, RANKL), in order to further explore the role of musculoskeletal ultrasonography in the diagnosis and monitoring of gouty arthritis. Methods: 160 cases of gouty arthritis from clinic of the Department of Rheumatology of Peking University People's Hospital between July 2016 and June 2017 were recruited in this study. These patients were examined by musculoskeletal ultrasonography (bilateral first metatarsophalangeal joints, bilateral ankle joints and bilateral knee joints). Grouping was based on ultrasound features of joints. Group A showed no aggregate .Group B showed aggregate and double contour signs. Group C showed tophus and bone erosion. Serum concentrations of Dickkopf-1 and RANKL were measured. The correlations of Dickkopf-1 or RANKL and clinical/laboratory parameters were analyzed. Results: (1)There was a significant difference in Dickkopf-1 concentration between the three groups(P<0.001). And the group C[(1 722.2±482.7)ng/L]was higher than the group B[(1 309.3±496.4)ng/L](t=4.418, P<0.001), and the group B was higher than group A[(807.9±373.8)ng/L](t=6.137, P<0.001). (2)There was a significant difference in RANKL concentration between the three groups (P<0.001). And the group C[(0.78±0.47)ng/L]was higher than the group B[(0.35±0.29)ng/L](t=5.456, P<0.001), and the group B was higher than group A[(0.10±0.09)ng/L](t=6.923, P<0.001). (3)The level of Dickkopf-1 was associated with the disease duration(r=0.430, P<0.001), and the level of RANKL was associated with the disease duration(r=0.359, P<0.001). Conclusion: Aggregates, double contour signs, tophus and bone erosion can be observed in the ultrasonic examination of gouty arthritis. And the longer the duration of the disease, the more likely the extent of bone destruction is. Joint ultrasound can be the first imaging examination for the extent of joint involvement in gouty arthritis. And the longer the duration of the disease, the more likely the extent of bone destruction is. Musculoskeletal ultrasonography can be the preferred imaging method for detecting the extent of joint involvement in gouty arthritis.

Differentially expressed genes in the ovary of the sixth day of pupal "Ming" lethal egg mutant of silkworm, Bombyx mori

The "Ming" lethal egg mutant (l-em) is a vitelline membrane mutant in silkworm, Bombyx mori. The eggs laid by the l-em mutant lose water, ultimately causing death within an hour. Previous studies have shown that the deletion of BmEP80 is responsible for the l-em mutation in silkworm, B. mori. In the current study, digital gene expression (DGE) was performed to investigate the difference of gene expression in ovaries between wild type and l-em mutant on the sixth day of the pupal stage to obtain a global view of gene expression profiles using the ovaries of three l-em mutants and three wild types. The results showed a total of 3,463,495 and 3,607,936 clean tags in the wild type and the l-em mutant libraries, respectively. Compared with those of wild type, 239 differentially expressed genes were detected in the l-em mutant, wherein 181 genes are up-regulated and 58 genes are down-regulated in the mutant strain. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis results showed that no pathway was significantly enriched and three pathways are tightly related to protein synthesis among the five leading pathways. Moreover, the expression profiles of eight important differentially expressed genes related to oogenesis changed. These results provide a comprehensive gene expression analysis of oogenesis and vitellogenesis in B. mori which facilitates understanding of both the specific molecular mechanism of the 1-em mutant and Lepidopteran oogenesis in general.

Transcriptional regulation of the gene for prothoracicotropic hormone in the silkworm, Bombyx mori

Prothoracicotropic hormone (PTTH) is one of key players in regulation of insect growth, molting, metamorphosis, diapause, and is expressed specifically in the two pairs of lateral PTTH-producing neurosecretory cells in the brain. Analysis of cis-regulatory elements of the PTTH promoter might elucidate the regulatory mechanism controlling PTTH expression. In this study, the PTTH gene promoter of Bombyx mori (Bom-PTTH) was cloned and sequenced. The cis-regulatory elements in Bom-PTTH gene promoter were predicted using Matinspector software, including myocyte-specific enhancer factor 2, pre-B-cell leukemia homeobox 1, TATA box, etc. Transient transfection assays using a series of fragments linked to the luciferase reporter gene indicated that the fragment spanning -110 to +33 bp of the Bom-PTTH promoter showed high ability to support reporter gene expression, but the region of +34 to +192 bp and -512 to -111 bp repressed the promoter activity in the BmN and Bm5 cell lines. Electrophoretic mobility shift assays demonstrated that the nuclear protein could specifically bind to the region spanning -124 to -6 bp of the Bom-PTTH promoter. Furthermore, we observed that the nuclear protein could specifically bind to the -59 to -30 bp region of the Bom-PTTH promoter. A classical TATA box, TATATAA, localized at positions -47 to -41 bp, which is a potential site for interaction with TATA box binding protein (TBP). Mutation of this TATA box resulted in no distinct binding band. Taken together, TATA box was involved in regulation of PTTH gene expression in B. mori.

Characterization of CIb1 gene promoter from silkworm, Bombyx mori

The hemolymph chymotrypsin inhibitor b1 (CIb1) of silkworm, Bombyx mori, plays an important role in innate immunity. In order to study its encoding gene CIb1, five heterogeneous promoter fragments of 844 bp, 682 bp, 516 bp, 312 bp and 82 bp in length were cloned from genomic DNA of the p50 silkworm strain. Characterization of the CIb1 promoter was performed in vitro using the firefly luciferase gene as reporter. The results showed that CIb1 promoter fragments have transcription activities in the B. mori ovary-derived BmN cell line. The 82 bp fragment (-72 to +10 nt) containing the eukaryotic core promoter elements revealed a basic transcription activity. The Bm1 element, upstream the transcription initiation site, showed a positive regulation function to the CIb1 promoter. CIb1 promoter-like fragments from the genomic DNA of the tetra hybrid silkworm SujuxMinghu provided a natural deletion model for the study of the CIb1 promoter. In vitro analysis indicated that the 132 bp fragment from -517 nt to -386 nt upstream of the transcription initiation site strongly suppressed the transcription activity of the CIb1 promoter, suggesting that the 132 bp fragment harbours strong negative cis-acting elements. Infection of Bombyx mori nucleopolyhedrovirus (BmNPV) increased the activity of the CIb1 promoter, having provided another evidence to the function of CIb1 in the innate immunity of silkworm.

Protein–DNA interactions in the promoter region of the gene encoding diapause hormone and pheromone biosynthesis activating neuropeptide of the cotton bollworm, Helicoverpa armigera

Diapause hormone (DH) and pheromone biosynthesis activating neuropeptide (PBAN) are two crucial neuropeptides which regulate insect development and sex pheromone biosynthesis respectively. These peptides are encoded by a single gene, termed DH-PBAN gene. In this study, we characterized the promoter of the DH-PBAN gene in Helicoverpa armigera (Har). Transient transfection assays using a series of stepwise deletion fragments linked to the luciferase reporter gene indicate that the promoter contains multiple regulator domains that can activate and repress reporter gene expression. The fragment spanning -467 to -371 bp of the DH-PBAN promoter is an activator domain of transcription, whereas the region from -965 to -534 bp represses the promoter activity in the insect cell line BmN. Electrophoretic mobility shift assays demonstrate that at least two nuclear protein factors from the nuclear protein extracts of H. armigera suboesophageal ganglion, Har-DHMBP-1 and-2 (DH-modulator-binding protein) can specifically bind to the activating region. Furthermore, we characterized in detail that the nuclear protein factor Har-DHMBP-3 can specifically bind to a classical E-box, CAGCTG localized at positions -360 to -355 bp, a potential site for interaction with basic helix-loop-helix transcription factors. Mutation of this E-box results in a significant reduction of the promoter activity, suggesting it can modulate the previously identified activator domain. Taken together, multipartite cis-elements and transcription factors in the DH-PBAN promoter are involved in regulation of the gene expression.

The ecdysteroid UDP-glucosyltransferase gene promoter from Autographa californica multicapsid nucleopolyhedrovirus

The ecdysteroid UDP-glucosyltransferase (egt) gene promoter fragments of different lengths were generated from the genomic DNA of the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) by PCR. After being purified and enzymatic digestion, they were cloned into the pGEM-3Z vector for construction of reporter plasmids pAcegt542-luc, pAcegt309-luc and pAcegt159-luc with the luciferase gene driven by the AcMNPV egt promoter. The results of transient expression in the Spodoptera frugiperda cell line-21 (Sf21) showed that the transcriptional activity of the AcMNPV egt promoter required the transactivation of viral factor(s). The expression of luciferase gene driven by the AcMNPV egt promoter was first detected at 24 h post infection. The egt promoter from the Bombyx mori nucleopolyhedrovirus (BmNPV), closely related to AcMNPV, revealed similar properties to that of the AcMNPV egt promoter. When BmNPV homologous region 3 was subcloned downstream the luciferase gene, the luciferase activity of the reporter plasmid was enhanced by over 1000-fold, but the property of the promoter was not changed. As a substrate of ecdysteroid UDP-glucosyltransferase (EGT), foreign insect ecdysone showed negative effects on egt promoter transcriptional activity. Ecdysone of 1.0-2.0 microg/ml significantly down-regulated the promoter activity. Promoter activities of different lengths showed that an AcMNPV egt promoter fragment of 159 bp has the basal transcriptional activity but it was almost abolished only about 0.2% of that of 309 bp and 542 bp, respectively, and the nucleotide sequence from - 159 to - 309 nt upstream the translation initiation site includes the main cis-acting elements interacting with viral factors.

Tensile properties, tension-tension fatigue and biological response of polyetheretherketone-hydroxyapatite composites for load-bearing orthopedic implants

Polyetheretherketone-hydroxyapatite composites were developed as alternative materials for load-bearing orthopedic applications. The amount of hydroxyapatite (HA) incorporated into the polyetheretherketone (PEEK) polymer matrix ranges from 5 to 40 vol% and these materials were successfully fabricated by injection molding. This study presents the mechanical and biological behavior of the composite materials developed. It was found that the amount of HA in the composite influenced the tensile properties. Dynamic behavior under tension-tension fatigue revealed that the fatigue-life of PEEK-HA composites were dependent on the HA content as well as the applied load. The biological responses of PEEK-HA composites carried out in vivo verified the biocompatibility and bioactive nature of the composite materials.

Hard metal lung disease--the first case in Singapore

INTRODUCTION

We report the first case of hard metal lung disease in Singapore and the occupational investigative work and control measures that were undertaken.

CLINICAL PICTURE

A 38-year-old machinist in the tool manufacturing industry presented with exertional dyspnoea and cough. Chest X-ray revealed bilateral reticulonodular infiltrates with honeycombing. High resolution computed tomography scan of the thorax confirmed the presence of interstitial fibrosis. Open biopsy of the lung showed features of pneumoconiosis. Particle induced X-ray emission (PIXE) analysis, a relatively new elemental analysis technique, performed on the lung biopsy specimen confirmed the presence of tungsten and titanium; and he was diagnosed to have hard metal lung disease. Microbiologic, serologic and histologic investigations excluded an infective cause. Serial pulmonary function tests on follow-up showed no progression. He presented with haemoptysis 10 months later and was diagnosed to have tuberculosis on the basis of positive sputum and bronchoalveolar lavage cultures for Mycobacterium tuberculosis complex.

TREATMENT

Preventive measures and permanent transfer to non-cobalt work were instituted.

OUTCOME

The interstitial fibrosis appears to have stabilised.

CONCLUSION

The diagnosis of hard metal lung disease must be considered in a worker exposed to cobalt presenting with interstitial fibrosis.

IS element ISXC6 of Xanthomonas campestris pv. campestris

An insertion sequence element, ISXC6, was isolated from Xanthomonas campestris pv. campestris 17 (Xc17). Sequence analysis showed that it is 1,500 bp long and has 20-bp perfect inverted repeat ends. Upon transposition, a direct repeat TAATTC was generated, flanking this IS. No significant homology was observed between this sequence and other sequences in database. Results of Southern hybridization showed that multiple copies of ISXC6 were present in 7 strains of Xanthomonas examined.

Monitoring statistics which have increased power over a reduced time range

The problem of monitoring trends for changes at unknown times is considered. Statistics which permit one to focus high power on a segment of the monitored period are studied. Numerical procedures are developed to compute the null distribution of these statistics.

The relationship between systolic anterior motion of the mitral valve and the left ventricular outflow tract Doppler in hypertrophic cardiomyopathy

In an attempt to investigate the role of left ventricular blood outflow in the generation of systolic anterior motion (SAM) of the mitral valve in patients with hypertrophic cardiomyopathy, we precisely analyzed the temporal relation of SAM and the left ventricular outflow tract (LVOT) systolic Doppler events obtained at the maximal mitral-septal apposition or equivalent area in eight patients with severe SAM, in five patients with mild/moderate SAM, and in seven patients with no SAM, using M-mode and pulsed Doppler echocardiography; the results were compared with those in 10 normal subjects. In all 13 patients with SAM, the timing of SAM generation corresponded to the LVOT Doppler events either between the onset of SAM and the onset of Doppler (r = 0.834, p less than 0.0001) or between the peak of SAM and the peak of Doppler (r = 0.836, p less than 0.0001). The excursion rate of the development of SAM showed a correlation with the LVOT blood outflow acceleration (r = 0.828, p less than 0.0001). The timing of SAM resolution also correlated with the Doppler events, either between the offset of SAM and the offset of Doppler (r = 0.795, p less than 0.001) or the end of SAM and the end of Doppler (r = 0.859, p less than 0.0001). The LVOT blood outflow deceleration showed a correlation with the regression rate of SAM (r = 0.668, p less than 0.013). The LVOT blood outflow acceleration was significantly higher in patients with severe SAM than in patients with mild/moderate SAM or no SAM. This study suggests that the high LVOT blood outflow acceleration in early systole possibly plays an important part in the generation of the Bernoulli pressure drop and results in anterior motion of the mitral valve. At mid-systole, a drag force and/or suction effect of pressure drop produced by continuous outflow blood may sustain the anterior motion of the mitral valve. At late systole, as the blood flow decelerates, the regression of SAM then occurs.

[Hair zinc and copper concentration in patients with epilepsy]

The concentration of zinc and copper in the hair of 55 patients with epilepsy was determined. The hair copper levels in patients with epilepsy were significantly lower than those in the normal control group (P less than 0.001). The hair zinc levels in female patients were significantly lower than those in the normal control group (P less than 0.05). In the following patients: (1) with generalized seizure, (2) with the disease course 0-5 years, (3) EEG showed heavy or middle abnormality, (4) had epileptic attacks within one year before the sample was taken, the zinc levels were also significantly lower compared with controls (P less than 0.05). Antiepileptic drugs had more effect on hair zinc than on copper. The increase in the hair zinc and copper and zinc: copper ratio seems to show the efficiency of drugs.

The effect of autocorrelated errors on change-detection statistics

In this paper, regression models with error terms generated by lower order ARMA schemes are analyzed. Methods are discussed for estimating the parameters of the regression coefficients and the ARMA processes. The problem of detecting changes in the regression parameters is considered. A change-detection statistic proposed by MacNeill (1978) for regression problems is modified for application to ARMA processes. The effect of autocorrelated errors on this statistic is briefly discussed.

Strontium/calcium ratio analysis of molluscan shells in Singapore waters using the X-ray fluorescence technique

The Sr/Ca ratios in molluscan shells in Singapore waters were measured using the X-ray fluorescence (XRF) technique. Our results show that the Sr/Ca ratio varies greatly among different species. However, within the same species, this ratio is practically the same for samples collected from sites close together but varies significantly for samples from sites far apart. Furthermore, this study shows that whole shell analysis using the XRF technique is simple and quick and that its application to environmental monitoring seems feasible.