Estimation of indoor (220)Rn progeny concentrations with (220)Rn measurements

For estimating indoor thoron ((220)Rn) progeny concentrations with (220)Rn measurements, both theoretical studies and field measurements were carried out in this work. Based on the theoretical study, it was found that the exhalation rate of (220)Rn (E(Tn)) could be optimally assessed with the (220)Rn concentration measured at a point of 50 cm far from the source wall, and the equilibrium equivalent thoron concentration (EETC) could be further estimated with the E(Tn) and the area of wall surface as well as the room volume. Field measurements testified that the estimated EETCs were in general agreement with the directly measured results with an average ratio of 0.87 ± 0.12. The new method developed in this study is thought to be preferable for long-term and large-scale surveys of indoor EETC.

Long-term outcome of patients with lamivudine after early cessation of hepatitis B immunoglobulin for prevention of recurrent hepatitis B following liver transplantation

BACKGROUND

The aim of this study is to examine the efficacy of long-term prophylaxis with lamivudine (LAM) after a course of post-operative hepatitis B immunoglobulin (HBIG) in patients who underwent liver transplantation (LT) for hepatitis B virus (HBV)-related disease.

RESULT

The medical records of HBV-infected patients who underwent a LT in our institution between July 2001 and May 2005 were reviewed. There were 15 liver transplant recipients who were administered HBIG for <18 months and used LAM as a maintenance prophylaxis regime enrolled in this study. At enrollment, all patients were hepatitis B surface antigen (HBsAg) positive and three patients were HBeAg positive. There were 13 patients who were HBV DNA positive with a mean viral load of 5.4 log copies/mL, and among them, 12 recipients were on antiviral therapy with LAM (100 mg/d orally) for 12-168 d, resulting in HBV DNA negative levels in nine patients prior to their transplant. HBV recurrence post-LT was noted in two patients who had very high-HBV DNA levels pre-LT. Both of these patients showed LAM-resistant mutation at the time of recurrence. The 11 patients who were HBV DNA negative before LT (low-risk patients) had no HBV recurrence during a follow-up at a median of 58 months post-LT. This included five patients who had intermittent low-level HBV DNA post-LT (HBsAg negative), of whom two had YMDD mutation and these two were given adefovir in addition to LAM.

CONCLUSION

Our retrospective study demonstrated excellent long-term outcomes in the low-risk patients treated with LAM after a short course of HBIG.

Fabrication and mechanical properties of PLLA/PCL/HA composites via a biomimetic, dip coating, and hot compression procedure

Currently, the bone-repair biomaterials market is dominated by high modulus metals and their alloys. The problem of stress-shielding, which results from elastic modulus mismatch between these metallic materials and natural bone, has stimulated increasing research into the development of polymer-ceramic composite materials that can more closely match the modulus of bone. In this study, we prepared poly(L: -lactic acid)/hydroxyapatite/poly(epsilon-caprolactone) (PLLA/HA/PCL) composites via a four-step process, which includes surface etching of the fiber, the deposition of the HA coating onto the PLLA fibers through immersion in simulated body fluid (SBF), PCL coating through a dip-coating process, and hot compression molding. The initial HA-coated PLLA fiber had a homogeneous and continuous coating with a gradient structure. The effects of HA: PCL ratio and molding temperature on flexural mechanical properties were studied and both were shown to be important to mechanical properties. Mechanical results showed that at low molding temperatures and up to an HA: PCL volume ratio of 1, the flexural strain decreased while the flexural modulus and strength increased. At higher mold temperatures with a lower viscosity of the PCL a HA: PCL ratio of 1.6 gave similar properties. The process successfully produced composites with flexural moduli near the lower range of bone. Such composites may have clinical use for load bearing bone fixation.

The association between intensive glycemic control and vascular complications in type 2 diabetes mellitus: a meta-analysis

BACKGROUND AND AIM

In patients with type 2 diabetes mellitus, the relationship between lowering glycated hemoglobin (HbA(1c)) and macrovascular complications is not clear and therefore lowering the level of HbA(1c) is controversial.

METHODS AND RESULTS

We searched for all randomized controlled trials comparing the effects of intensive and standard glycemic control on vascular events in patients with type 2 diabetes mellitus. The primary endpoint was combined macrovascular complications, including cardiac events, stroke and peripheral vascular disease. Fixed and random effect models were used to analyze the results. Eight studies were included according to selection criteria. The results showed no benefits of intensive glycemic control on macrovascular and microvascular complications (P>0.1), but a higher rate of severe hypoglycemia (P<0.00001) in the intensive control group when the target HbA(1c) level was <7.0%. When the target HbA(1c) level was lowered to 7.0-7.9%, intensive glycemic control showed benefits on the reduction of microvascular events (P<0.05) without increasing the risk of severe hypoglycemia (P=0.74), but no influence on macrovascular complications (P>0.1).

CONCLUSION

The results of this analysis suggest that a target HbA(1c) level of 7.0-7.9% may be a better glycemic control target than that of <7.0% in patients with established type 2 diabetes mellitus.

Pump Prime Aprotinin Fails to Limit Proinflammatory Cytokine Release After Coronary Artery Bypass Surgery

BACKGROUND

The purpose of this study was to establish whether pump prime aprotinin could limit the cytokine responses in patients undergoing elective coronary artery bypass surgery.

METHODS

Twenty-one patients admitted for first-time elective coronary artery bypass surgery were randomized into control or aprotinin groups. Patients in the aprotinin group received 280 mg aprotinin in the pump prime. Leukocyte count, creatine kinase cardiac isoenzyme (CK-MB), cytokine production and postoperative blood loss were analyzed perioperatively and compared with preoperative values.

RESULTS

The peak level of leukocyte count was lower in the aprotinin group than in controls (9.3 +/- 0.58 vs 11.2 +/- 0.68 x 10(9)/L, p = 0.01). Interleukin (IL)-6 and IL-8 did not differ significantly between the groups throughout the study period. Plasma IL-10 levels were higher in the controls than in the aprotinin group at 5 min (49.6 +/- 24.9 vs 8.13 +/- 2.8 pg/ml, p = 0.01) after reperfusion.

CONCLUSION

Pump prime aprotinin fails to limit proinflammatory cytokine response in circulating blood.

Short-interfering RNA-mediated silencing of proliferating cell nuclear antigen inhibit proliferation and induce apoptosis in HeLa cells

Proliferating cell nuclear antigen (PCNA) is an important protein for DNA polymerase delta in the nucleus, and shown to have a fundamental role in cellular proliferation. It is overexpressed to support cell growth in cervical carcinoma. To study its role in stress response, we design and use short hairpin RNA (shRNA) to inhibit PCNA expression in HeLa cells and validate its effect on cell proliferation. In this study, three PCNA-shRNA expression vectors are constructed and introduced into HeLa cells, and the cell cycle is analyzed by flow cytometry. Apoptotic cell is detected by single cell gel electrophoresis assay (comet assay), and caspase cleavage is studied also. Expression of PCNA is assessed by real-time reverse transcription-polymerase chain reaction and Western blot analysis. Upon transient transfection with plasmid encoding shRNA, it is found that expression of PCNA decreased in shRNA-transfected cells, downregulation of PCNA inhibit cell growth and induce apoptosis in HeLa cells. PCNA downregulation also increase cell population in the G0-G1 phase. In conclusion, our findings demonstrate that shRNA can inhibit the DNA replication and induce apoptosis in HeLa cells effectively and, therefore, could be used as a new potential anticancer tool for therapy of human cervical carcinoma.

Imprinting of PEG1/MEST Isoform 2 in Human Placenta

The PEG1 gene (a.k.a. MEST) is expressed in human placental trophoblast and endothelium, and data from knockout mice show that this gene regulates placental and fetal growth. Isoform 1 of PEG1 mRNA initiates from exon 1c and produces the long form of the MEST protein. This isoform is imprinted, with expression only from the paternal allele in many human and mouse organs, including placenta. In contrast, PEG1 isoform 2, initiating from exon 1a and producing the short form of MEST protein, is biallelically expressed (non-imprinted) in several non-placental organs. Here we show that PEG1 isoform 2 is in fact imprinted in a large subset of human placentae. A CpG island overlapping PEG1 exon 1a is unmethylated in various fetal and adult non-placental tissues, but is often substantially methylated in the placenta, with the extent of methylation in a large series approximating a normal distribution. Bisulfite conversion/sequencing indicates that the inter-individual differences reflect the relative representation of heavily methylated vs. unmethylated alleles, and RT-PCR/RFLP analysis shows strongly biased allelic expression of PEG1 isoform 2 mRNA in a majority of placentae with a high proportion of methylated alleles. These data highlight PEG1 isoform 2 as a marker for future studies of inter-individual epigenetic variation and its relation to placental and fetal growth in humans.

Unbalanced placental expression of imprinted genes in human intrauterine growth restriction

Imprinted genes control fetal and placental growth in mice and in rare human syndromes, but the role of these genes in sporadic intrauterine growth restriction (IUGR) is less well-studied. We measured the ratio of mRNA from a maternally expressed imprinted gene, PHLDA2, to that from a paternally expressed imprinted gene, MEST, by Northern blotting in 38 IUGR-associated placentae and 75 non-IUGR placentae and found an increase in the PHLDA2/MEST mRNA ratio in IUGR (p=0.0001). Altered expression of PHLDA2 and MEST was not accompanied by changes in DNA methylation within their imprinting centers, and immunohistochemistry showed PHLDA2 protein appropriately restricted to villous and intermediate cytotrophoblast in the IUGR placentae. We next did a genome-wide survey of mRNA expression in 14 IUGR placentae with maternal vascular under-perfusion compared to 15 non-IUGR placentae using Affymetrix U133A microarrays. In this series six imprinted genes were differentially expressed by ANOVA with a Benjamini-Hochberg false discovery rate of 0.05, with increased expression of PHLDA2 and decreased expression of MEST, MEG3, GATM, GNAS and PLAGL1 in IUGR placentae. At lower significance, we found IGF2 mRNA decreased and CDKN1C mRNA increased in the IUGR cases. We confirmed the significant reduction in MEG3 non-translated RNA in IUGR placentae by Northern blotting. In addition to imprinted genes, the microarray data highlighted non-imprinted genes acting in endocrine signaling (LEP, CRH, HPGD, INHBA), tissue growth (IGF1), immune modulation (INDO, PSG-family genes), oxidative metabolism (GLRX), vascular function (AGTR1, DSCR1) and metabolite transport (SLC-family solute carriers) as differentially expressed in IUGR vs. non-IUGR placentae.

Incorporation of fluorine ions into hydroxyapatite by a pH cycling method

Fluorine ions were incorporated into hydroxyapatite (HA) using a pH cycling method and the resulting materials were studied using transmission electron microscopy (TEM), X-ray diffraction (XRD), and electrochemical analysis. TEM observations showed that fluoridated hydroxyapatite (FHA) nanoparticles with a narrow particle size distribution were obtained at several different levels of fluorine incorporation. Significant particle growth was observed following calcining at 1200 degrees C. The TEM data revealed that, instead of forming laminated structures, a mixture of HA and FA was obtained, and that this mixture transformed into a single homogeneous FHA phase upon heating. It was found that the efficiency of fluorine incorporation did not vary significantly with the initial HA particle size, but increased as the fluorine content of the initial solution was increased. A relatively low fluorine incorporation efficiency, approximately 60%, was attained for most of the FHA samples and this was attributed to the short holding time at each pH cycle and the limited number of pH cycles employed in the current study.

Influence of temperature and aging time on HA synthesized by the hydrothermal method

The influence of temperature and aging time on the morphology and mechanical properties of nano-sized hydroxyapatite (HA) synthesized by a hydrothermal method is reported here. The pre-mixed reactants were poured into a stirred autoclave and reacted at temperatures between 25-250 degrees C for 2-10 h. HA powders thus obtained were examined using X-ray diffraction (XRD), high-resolution field emission scanning electron microscopy (FESEM) and a particle size analyzer. It was found that the aspect ratio of the particles increased with the reaction temperature. The length of the HA particles increased with the reaction temperature below 170 degrees C, but it decreased when the temperature was raised above 170 degrees C. The agglomerates of HA particles were formed during synthesis, and their sizes were strongly dependent on reaction temperatures. As the reaction temperature increased, the agglomerate size decreased (p = 0.008). The density of the discs pressed from these samples reached 85-90% of the theoretical density after sintering at 1200 degrees C for 1 h. No decomposition to other calcium phosphates was detected at this sintering temperature. A correlation existed (p = 0.05) between the agglomerate sizes of HA particles synthesized at various conditions and their sintered densities. With the increase of the agglomerate size, the sintered density of the HA compact decreased. It was found that both the sintered density and flexural strength increased with increasing aging time and reaction temperature. A maximum flexural strength of 78 MPa was observed for the samples synthesized at 170 degrees C for 5 h with the predicted average at these conditions being 65 MPa. These samples attained an average sintered density of 88%.

Precipitation of hydroxyapatite nanoparticles: effects of precipitation method on electrophoretic deposition

Electrophoretic deposition is a low-cost, simple, and flexible coating method for producing hydroxyapatite (HA) coatings on metal implants with a broad range of thicknesses, from < 1 microm to > 500 microm. As for many other HA coating techniques, densification of electrophoretically deposited coatings involves heating the coated metal to temperatures above 1000 degrees C. Metal substrates tend to react with HA coatings at such temperatures inducing decomposition at temperatures below 1050 degrees C (decomposition for pure HA normally occurs above 1300 degrees C). Therefore, densification of these coatings needs to be conducted at temperatures lower than 1050 degrees C, and this necessitates the use of high-surface-area HA nano-precipitates, rather than commercially available pre-calcined powders, which densify at temperatures typically higher than 1200 degrees C. HA nano-precipitates were prepared by three methods and deposited on metal substrates by electrophoresis: (1) the acid base method, which produced plate-like nano-particles with a 2.5:1 aspect ratio, and severely cracked coatings; (2) the calcium acetate method, which produced needle-like nano-particles with a 10:1 aspect ratio, and slightly cracked coatings; (3) the metathesis method, which produced rounded nano-particles with a 2:1 aspect ratio, and high-quality crack-free coatings. The results suggested that the less equiaxed the nano-particles, the more cracked the coatings obtained by the electrophoretic deposition technique.

Hydroxyapatite-coated metals: interfacial reactions during sintering

Electrophoretic deposition (EPD) is a low cost flexible process for producing HA coatings on metal implants. Its main limitation is that it requires heating the coated implant in order to densify the HA. HA typically sinters at a temperature below 1150 degrees C, but metal implants are degraded above 1000 degrees C. Further, the metal induces the decomposition of the HA coating upon sintering. Recent developments have enabled EPD of metathesis-synthesised uncalcined HA which sinters at approximately 1000 degrees C. The effects of temperature on HA-coated Ti, Ti6Al4V, and 316L stainless steel were investigated for dual coatings of metathesis HA sintered at 1000 degrees C. The use of dual HA coatings (coat, sinter, coat, sinter) enabled decomposition to be confined to the "undercoat" (HA layer 1), with the surface coating decomposition free. The tensile strength of the three metals was not significantly affected by the high sintering temperatures (925 degrees C < T < 1000 degrees C). XRD/SEM/EDS analyses of the interfacial zones revealed that 316L had a negligible HA:metal interfacial zone (approximately 1 microm) while HA:Ti and HA:Ti6Al4V had large interfacial zones (>10 microm) comprising a TiO2 oxidation zone and a CaTiO2 reaction zone.

Synthesis and characterization of fluorine-containing hydroxyapatite by a pH-cycling method

Different fluorine-containing hydroxyapatite (FHA) powders were synthesized through a pH-cycling method by varying sodium fluoride (NaF) concentration in hydroxyapatite (HA) suspensions. The powders were then calcined at 1200 ( composite function)C for 1 h. Both uncalcined and calcined powders were characterized using X-ray diffraction (XRD), Fourier transform infra-red (FTIR), and F-electrode. It was discovered that fluorine incorporation increased with the fluorine content in the initial solution and the number of pH cycles employed. A relatively low fluorine incorporation efficiency, approximately 60%, was attained for most of the FHA samples, and it did not vary significantly after calcination. It was also revealed that the FHA particles produced by the pH-cycling method were inhomogeneous. They were a mixture of hydroxyapatite and F-rich apatite (or FA) particles. After calcination, however, these FHA particles were homogenized and became single phased FHA.

Description and clinical treatment of an early outbreak of severe acute respiratory syndrome (SARS) in Guangzhou, PR China

Severe acute respiratory syndrome (SARS), now known to be caused by a coronavirus, probably originated in Guangdong province in southern China in late 2002. The first major outbreak occurred in Guangzhou, the capital of Guangdong, between January and March 2003. This study reviews the clinical presentation, laboratory findings and response to four different treatment protocols. Case notes and laboratory findings were analysed and outcome measures were collected prospectively. The SARS outbreak in Guangdong province and the outbreak in Guangzhou associated with hospitals in the city are described, documenting clinical and laboratory features in a cohort of 190 patients randomly allocated to four treatment regimens. Patients were infected by close contact in either family or health-care settings, particularly following procedures likely to generate aerosols of respiratory secretions (e.g. administration of nebulized drugs and bronchoscopy). The earliest symptom was a high fever followed, in most patients, by dyspnoea, cough and myalgia, with 24 % of patients complaining of diarrhoea. The most frequent chest X-ray changes were patchy consolidation with progression to bilateral bronchopneumonia over 5-10 days. Thirty-six cases developed adult respiratory distress syndrome (ARDS), of whom 11 died. There was no response to antibiotics. The best response (no deaths) was seen in the group of 60 patients receiving early high-dose steroids and nasal CPAP (continuous airway positive pressure) ventilation; the other three treatment groups had significant mortality. Cross-infection to medical and nursing staff was completely prevented in one hospital by rigid adherence to barrier precautions during contact with infected patients. The use of rapid case identification and quarantine has controlled the outbreak in Guangzhou, in which more than 350 patients have been infected. Early administration of high-dose steroids and CPAP ventilation appears to offer the best supportive treatment with a reduced mortality compared with other treatment regimens.