Enhancing the electronic and optical properties of the metal/semiconductor NbS2/BSe nanoheterostructure towards advanced electronics

Metal-semiconductor (M-S) contacts play a vital role in advanced applications, serving as crucial components in ultracompact devices and exerting a significant impact on overall device performance. Here, in this work, we design a M-S nanoheterostructure between a metallic NbS2 monolayer and a semiconducting BSe monolayer using first-principles prediction. The stability of such an M-S nanoheterostructure is verified and its electronic and optical properties are also considered. Our results indicate that the NbS2/BSe nanoheterostructure is structurally, mechanically and thermally stable. The formation of the NbS2/BSe heterostructure leads to the generation of a Schottky contact with the Schottky barrier ranging from 0.36 to 0.51 eV, depending on the stacking configurations. In addition, the optical absorption coefficient of the NbS2/BSe heterostructure can reach up to 5 × 105 cm-1 at a photon energy of about 5 eV, which is still greater than that in the constituent NbS2 and BSe monolayers. This finding suggests that the formation of the M-S NbS2/BSe heterostructure gives rise to an enhancement in the optical absorption of both NbS2 and BSe monolayers. Notably, the tunneling probability and the contact tunneling-specific resistivity at the interface of the NbS2/BSe heterostructure are low, indicating its applicability in emerging nanoelectronic devices, such as Schottky diodes and field-effect transistors. Our findings offer valuable insights for the practical utilization of electronic devices based on the NbS2/BSe heterostructure.

Selective detection of HBV pre-genomic RNA in chronic hepatitis B patients using a novel RT-PCR assay

In chronic hepatitis B (CHB) patients, quantification of HBV pgRNA in plasma has the potential to provide information on disease prognosis and liver injury or histopathology. However, current methods for detecting HBV pgRNA present technical difficulties due to the co-existence of HBV DNA in plasma samples. We have successfully established a novel one-step RT-PCR assay that allows selective quantification of HBV pgRNA. Two cohorts of participants were recruited for assay validation, including treatment-naïve patients with CHB and HBeAg-positive CHB patients who were treated with Tenofovir and monitored for 6 months to assess the predictive value of baseline HBV RNA for HBeAg seroclearance. Statistical analysis was performed using MedCalc version 20.019 software. The novel selective one-step RT-PCR assay for detecting HBV pgRNA was validated with a limit of detection of 100 copies/mL. The assay was able to selectively measure HBV pgRNA even in the presence of excess HBV rcDNA. In treatment-naïve CHB patients, HBV pgRNA levels were significantly lower than HBV DNA concentration. Serum HBV DNA levels and HBeAg status were positively associated with HBV pgRNA. Baseline serum HBV pgRNA levels were found to be strong predictors of HBeAg seroclearance after 6 months of Tenofovir treatment. The study presents a novel RT-PCR assay that allows accurate measurement of plasma HBV pgRNA in chronic hepatitis B patients, even in the presence of excess HBV DNA. The assay is highly selective and represents a significant advancement with potential for further breakthroughs in understanding the clinical significance of HBV pgRNA.

Tuberculin skin testing and QuantiFERON™-TB Gold Plus positivity among household contacts in Vietnam

SETTING

TB infection (TBI) is diagnosed using the technique-dependent tuberculin skin test (TST) or costly, more accurate interferon-gamma release assays. The TST (⩾10 mm) threshold was indicated by previous research among household contacts in Vietnam, but routine implementation with a different tuberculin reagent showed unexpectedly low TST positivity.

OBJECTIVE

TST (⩾5 mm and ⩾10 mm) results were compared to QuantiFERON™-TB Gold Plus (QFT) results in household contacts during community campaigns in 2020 and 2021.

DESIGN

This was a cross-sectional multi-center implementation study.

RESULTS

Among 1,330 household contacts in 2020, we found a TBI prevalence of 38.6% (QFT), similar to TST ⩾5 mm (37.4%) and higher than TST ⩾10 mm (13.1%). QFT+/TST+ was higher for TST ⩾5 mm (20.7%) than TST ⩾10 mm (9.4%). QFT was not discordant with TST ⩾5 mm (McNemar's test = 0.6, P = 0.5) but was discordant with TST ⩾10 mm (McNemar's test = 263.9, P < 0.01). Older age and Southern region increased odds for positive TST ⩾5 mm and QFT with weaker associations for TST ⩾10 mm. Agreement and discordance were similar in 2021 for 1,158 household contacts.

CONCLUSION

Tuberculin reagents affect TST positivity rates. High TB burden countries should monitor reliability of TBI diagnosis, including tuberculin potency, cold chain, and TST technique to optimize eligibility for TB preventive treatment.

Large-scale analysis of putative plasmids in clinical multidrug-resistant Escherichia coli isolates from Vietnamese patients

Introduction

In the past decades, extended-spectrum beta-lactamase (ESBL)-producing and carbapenem-resistant (CR) Escherichia coli isolates have been detected in Vietnamese hospitals. The transfer of antimicrobial resistance (AMR) genes carried on plasmids is mainly responsible for the emergence of multidrug-resistant E. coli strains and the spread of AMR genes through horizontal gene transfer. Therefore, it is important to thoroughly study the characteristics of AMR gene-harboring plasmids in clinical multidrug-resistant bacterial isolates.

Methods

The profiles of plasmid assemblies were determined by analyzing previously published whole-genome sequencing data of 751 multidrug-resistant E. coli isolates from Vietnamese hospitals in order to identify the risk of AMR gene horizontal transfer and dissemination.

Results

The number of putative plasmids in isolates was independent of the sequencing coverage. These putative plasmids originated from various bacterial species, but mostly from the Escherichia genus, particularly E. coli species. Many different AMR genes were detected in plasmid contigs of the studied isolates, and their number was higher in CR isolates than in ESBL-producing isolates. Similarly, the bla_KPC-2, bla_NDM-5, bla_OXA-1, bla_OXA-48, and bla_OXA-181 β-lactamase genes, associated with resistance to carbapenems, were more frequent in CR strains. Sequence similarity network and genome annotation analyses revealed high conservation of the β-lactamase gene clusters in plasmid contigs that carried the same AMR genes.

Discussion

Our study provides evidence of horizontal gene transfer in multidrug-resistant E. coli isolates via conjugative plasmids, thus rapidly accelerating the emergence of resistant bacteria. Besides reducing antibiotic misuse, prevention of plasmid transmission also is essential to limit antibiotic resistance.

Potential spread of mcr-9-carrying IncHI2 plasmids in Enterobacter hormaechei in Vietnam

OBJECTIVES

Mobile colistin resistance (mcr) genes are widely distributed around the world. To date, ten major variants of mcr genes are known (mcr-1 to mcr-10). However, only a few instances of Enterobacterales isolates harbouring mcr genes other than mcr-1 have been reported in Vietnam. The aim of this study was to investigate mcr-harbouring antimicrobial-resistant Enterobacterales isolates in Vietnam.

METHODS

Two mcr-9-harbouring Enterobacter hormaechei clinical isolates (NIHE14-1904 and MH17-539M) were obtained from medical institutions in Hanoi, Vietnam, in 2014 and 2017, respectively. Their genomes and plasmid sequences were analysed by short-read and long-read sequencing. Subsequently, comparative sequence analysis of their mcr-9-carrying plasmids was performed.

RESULTS

Strains NIHE14-1904 and MH17-539M belonged to sequence types ST916 and ST66, respectively, according to the Enterobacter cloacae multilocus sequence typing (MLST) scheme. NIHE14-1904 and MH17-539M harboured the mcr-9 gene on similar IncHI2 plasmids, namely pNIHE14-1904-mcr9 (373.1 kb) and pMH17-539M-mcr9 (289.3 kb), respectively. These plasmids were also highly identical to widespread IncHI2 plasmids that are often associated with mcr genes.

CONCLUSION

For the first time, mcr-9-harbouring Enterobacterales isolates were detected in Vietnam, which carried mcr-9 on IncHI2 plasmids. The prevalence of such plasmids needs to be monitored in the future owing to their high dissemination.

Plasmid analysis of NDM metallo-β-lactamase-producing Enterobacterales isolated in Vietnam

Carbapenem-resistant Enterobacterales (CRE) represent a serious threat to public health due to the lack of treatment and high mortality. The rate of antimicrobial resistance of Enterobacterales isolates to major antimicrobials, including carbapenems, is much higher in Vietnam than in Western countries, but the reasons remain unknown due to the lack of genomic epidemiology research. A previous study suggested that carbapenem resistance genes, such as the carbapenemase gene blaNDM, spread via plasmids among Enterobacterales in Vietnam. In this study, we characterized blaNDM-carrying plasmids in Enterobacterales isolated in Vietnam, and identified several possible cases of horizontal transfer of plasmids both within and among species of bacteria. Twenty-five carbapenem-nonsusceptible isolates from a medical institution in Hanoi were sequenced on Illumina short-read sequencers, and 13 blaNDM-positive isolates, including isolates of Klebsiella pneumoniae, Escherichia coli, Citrobacter freundii, Morganella morganii, and Proteus mirabilis, were further sequenced on an Oxford Nanopore Technologies long-read sequencer to obtain complete plasmid sequences. Almost identical 73 kb IncFII(pSE11)::IncN hybrid plasmids carrying blaNDM-1 were found in a P. mirabilis isolate and an M. morganii isolate. A 112 kb IncFII(pRSB107)::IncN hybrid plasmid carrying blaNDM-1 in an E. coli isolate had partially identical sequences with a 39 kb IncR plasmid carrying blaNDM-1 and an 88 kb IncFII(pHN7A8)::IncN hybrid plasmid in a C. freundii isolate. 148-149 kb IncFIA(Hl1)::IncA/C2 plasmids and 75-76 kb IncFII(Yp) plasmids, both carrying blaNDM-1 were shared among three sequence type 11 (ST11) isolates and three ST395 isolates of K. pneumoniae, respectively. Most of the plasmids co-carried genes conferring resistance to clinically relevant antimicrobials, including third-generation cephalosporins, aminoglycosides, and fluoroquinolones, in addition to blaNDM-1. These results provide insight into the genetic basis of CRE in Vietnam, and could help control nosocomial infections.

Emergence of a plasmid-borne tigecycline resistance in Klebsiella pneumoniae in Vietnam

Tigecycline is a last-resort antimicrobial used to treat multidrug-resistant Gram-negative bacterial infections. One of the common antimicrobial resistance mechanisms is the efflux pump system composed of membrane protein complexes to excrete xenobiotic substrates. Recently, a novel gene cluster, tmexCD1-toprJ1, encoding the resistance-nodulation-cell division (RND) efflux pump was identified on plasmids in Klebsiella pneumoniae isolates in China. TMexCD1-TOprJ1 was found to be capable of excreting multiple antimicrobials, including tigecycline, which contributed to the strain's resistance. In this study, we identified K. pneumoniae isolates harbouring the tmexCD1-toprJ1 genes outside of China for the first time. Two tigecycline-resistant K. pneumoniae isolates belonging to ST273 by multilocus sequence typing were collected from different patients in a medical institution in Hanoi, Vietnam, in 2015. Whole-genome sequence analysis revealed that these isolates harboured a 288.0 kb tmexCD1-toprJ1-carrying plasmid with IncFIB and IncHI1B replicons. The tmexCD1-toprJ1 gene cluster was surrounded by several mobile gene elements, including IS26, and the plasmids had high sequence identity with that of K. pneumoniae isolated in China. Our finding suggests that the horizontal spread of tigecycline resistance mediated by tmexCD1-toprJ1-carrying plasmids has occurred in Vietnam and other countries, and raises concern about the further global dissemination.

Prospective One Health genetic surveillance in Vietnam identifies distinct blaCTX-M-harbouring Escherichia coli in food-chain and human-derived samples

OBJECTIVES

We performed a One Health surveillance in Hanoi-a region with a high-density human population and livestock production, and a recognized hotspot of animal-associated antimicrobial resistance (AMR)-to study the contribution of bla_CTX-M-carrying Escherichia coli and plasmids from food-animal sources in causing human community-acquired urinary tract infections (CA-UTIs).

METHODS

During 2014-2015, 9090 samples were collected from CA-UTI patients (urine, n = 8564), pigs/chickens from farms and slaughterhouses (faeces, carcasses, n = 448), and from the slaughterhouse environment (surface swabs, water, n = 78). E. coli was identified in 2084 samples. Extended-spectrum β-lactamase (ESBL) production was confirmed in 235 and bla_CTX-M in 198 strains by PCR with short-read plasmid sequencing. Fourteen strains were long-read sequenced to enable plasmid reconstruction.

RESULTS

The majority of the ESBL-producing E. coli strains harboured bla_CTX-M (n = 198/235, 84%). High clonal diversity (48 sequence types, STs) and distinct, dominant STs in human sources (ST1193, n = 38/137; ST131, n = 30/137) and non-human sources (ST155, n = 25/61) indicated lack of clonal transmission between habitats. Eight bla_CTX-M variants were identified; five were present in at least two sample sources. Human and food-animal strains did not show similar plasmids carrying shared bla_CTX-M genes. However, IS6 elements flanking ISEcp1-bla_CTX-M-orf477/IS903B structures were common across habitats.

CONCLUSIONS

In this study, animal-associated bla_CTX-ME. coli strains or bla_CTX-M plasmids were not direct sources of CA-UTIs or ESBL resistance in humans, respectively, suggesting evolutionary bottlenecks to their adaptation to a new host species. Presence of common IS6 elements flanking bla_CTX-M variants in different plasmid backbones, however, highlighted the potential of these transposable elements for AMR transmission either within or across habitats.

Quadruple-first line drug resistance in Mycobacterium tuberculosis in Vietnam: What can we learn from genes?

In Vietnam, a country with high tuberculosis (137/100.000 population) and multidrug-resistant (MDR)-TB burdens (7.8/100.000 population), little is known about the molecular signatures of drug resistance in general and more particularly of second line drug (SLD) resistance. This study is specifically focused on Mycobacterium tuberculosis isolates resistant to four first-line drugs (FLDs) that make TB much more difficult to treat. The aim is to determine the proportion of SLD resistance in these quadruple drug resistant isolates and the genetic determinants linked to drug resistance to better understand the genetic processes leading to quadruple and extremely drug resistance (XDR). 91 quadruple (rifampicin, isoniazid, ethambutol and streptomycin) FLD resistant and 55 susceptible isolates were included. Spoligotyping and 24-locus MIRU-VNTR techniques were performed and 9 genes and promoters linked to FLD and SLD resistance were sequenced. SLD susceptibility testing was carried out on a subsample of isolates. High proportion of quadruple-FLD resistant isolates was resistant to fluoroquinolones (27%) and second-line injectable drugs (30.2%) by drug susceptibility testing. The sequencing revealed high mutation diversity with prevailing mutations at positions katG315, inhA-15, rpoB531, embB306, rrs1401, rpsL43 and gyrA94. The sensitivity and specificity were high for most drug resistances (>86%), but the sensitivity was lower for injectable drug resistances (<69%). The mutation patterns revealed 23.1% of pre-XDR and 7.7% of XDR isolates, mostly belonging to Beijing family. The genotypic diversity and the variety of mutations reflect the existence of various evolutionary paths leading to FLD and SLD resistance. Nevertheless, particular mutation patterns linked to high-level resistance and low fitness costs seem to be favored.

Evaluation of the integrated clinic model for HIV/AIDS services in Ho Chi Minh City, Viet Nam, 2013-2014

Setting: Ho Chi Minh City (HCMC), Viet Nam. Objective: To evaluate a new integrated service model for human immunodeficiency virus/acquired immune-deficiency syndrome (HIV/AIDS) care. Design: In HCMC, co-located services, including voluntary HIV counseling and testing (VCT), HIV treatment at out-patient clinics (OPC), and methadone maintenance therapy (MMT) for persons who inject drugs, have operated under different administrative structures. In the context of decreasing international financial support, integration of these services into one administrative structure with reduced staff occurred in seven districts in HCMC between October 2013 and June 2014. We used a pre-post study design to compare service-related outcomes from routinely collected data at health facilities 6 months before and 6 months after integration. Results: The proportion of HIV-infected persons linked from VCT to OPCs was unchanged or increased following integration. A higher percentage of patients eligible for antiretroviral therapy (ART) were started on ART. The proportion of ART patients lost to follow-up remained unchanged. The proportions of MMT patients who tested positive for heroin or other substances decreased or were unchanged. Conclusions: VCT, OPC and MMT service delivery quality remained the same or improved during the 6 months following the integration. Expansion of the integrated model should be considered for HIV-related services.

Membrane foulants and fouling mechanisms in microfiltration and ultrafiltration of an activated sludge effluent

Membrane fouling in microfiltration (MF) and ultrafiltration (UF) of an activated sludge (AS) effluent was investigated. It was found that the major membrane foulants were polysaccharides, proteins, polysaccharide-like and protein-like materials and humic substances. MF fouling by the raw effluent was governed by pore adsorption of particles smaller than the pores during the first 30 minutes of filtration and then followed the cake filtration model. UF fouling could be described by the cake filtration model throughout the course of filtration. Coagulation with alum and (poly)aluminium chlorohydrate (ACH) altered the MF fouling mechanism to follow the cake filtration model from the beginning of filtration. The MF and UF flux improvement by coagulation was due to the removal of some of the foulants in the raw AS effluent by the coagulants. The MF flux improvement was greater for alum than for ACH whereas the two coagulants performed equally well in UF. Coagulation also reduced hydraulically irreversible fouling on the membranes and this effect was more prominent in MF than in UF. The unified membrane fouling index (UMFI) was used to quantitatively evaluate the effectiveness of coagulation on membrane flux enhancement.

Functionalized graphene sheets for polymer nanocomposites

Polymer-based composites were heralded in the 1960s as a new paradigm for materials. By dispersing strong, highly stiff fibres in a polymer matrix, high-performance lightweight composites could be developed and tailored to individual applications. Today we stand at a similar threshold in the realm of polymer nanocomposites with the promise of strong, durable, multifunctional materials with low nanofiller content. However, the cost of nanoparticles, their availability and the challenges that remain to achieve good dispersion pose significant obstacles to these goals. Here, we report the creation of polymer nanocomposites with functionalized graphene sheets, which overcome these obstacles and provide superb polymer-particle interactions. An unprecedented shift in glass transition temperature of over 40 degrees C is obtained for poly(acrylonitrile) at 1 wt% functionalized graphene sheet, and with only 0.05 wt% functionalized graphene sheet in poly(methyl methacrylate) there is an improvement of nearly 30 degrees C. Modulus, ultimate strength and thermal stability follow a similar trend, with values for functionalized graphene sheet- poly(methyl methacrylate) rivaling those for single-walled carbon nanotube-poly(methyl methacrylate) composites.

Long-term complications of platinum-based chemotherapy in testicular cancer survivors

The purpose of this study was to describe the rates of cardiovascular and other medical complications related to the use of platinum-based chemotherapy in American testicular cancer survivors. The study sample consisted of 143 eligible long-term testicular cancer survivors. Participants were interviewed, their medical records were reviewed, and blood was obtained for cholesterol measurement during their follow-up visit. The mean follow-up time was 8.4 yr, and their mean age at follow-up was 41.2 yr; 72.7% had had non-seminoma, and 82.5% had received platinum-based chemotherapy. Hypertension rates in the platinum-treated group increased significantly from baseline to follow-up; however, once adjusted for blood pressure measurement (undiagnosed hypertension), no such increase was seen, and hypertension rates were already higher than national estimates at baseline in all groups. At the follow-up visit, the rates of hyperlipidemia (adjusted for measured cholesterol level) in both platinum- and non-platinum-treated groups (28.4% and 37.5%, respectively) were higher than national estimates (16.9%). Rates of coronary artery disease were higher in those who had received platinum and radiation (11.1%) than in those who had received platinum alone (4.3%), but this difference was not statistically significant. As suggested by previous studies, platinum-based chemotherapy may be associated with hypertension, hyperlipidemia, and coronary artery disease. However, our data suggest that undiagnosed hypertension and hyperlipidemia may be significant confounders, and we also observed a trend toward lower testosterone levels in participants who experienced cardiovascular complications.

Infantile spasm-associated microencephaly in tuberous sclerosis complex and cortical dysplasia

OBJECTIVE

In children with and without infantile spasms, this study determined brain volumes and cell densities in epilepsy surgery patients with tuberous sclerosis complex (TSC) and cortical dysplasia with balloon cells (CD).

METHODS

We compared TSC (n = 18) and CD (n = 17) patients with normal/autopsy controls (n = 20) for MRI gray and white matter volumes and neuronal nuclei (NeuN) cell densities.

RESULTS

In patients without a history of infantile spasms, TSC cases showed decreased gray and white matter volumes (-16%). In cases with a history of infantile spasms, both CD (-25%) and TSC (-35%) patients showed microencephaly. This was confirmed in monozygotic twins with TSC, where the twin with a history of spasms had cerebral volumes less (-16%) than the twin without a history of seizures. Regardless of seizure history, TSC patients showed decreased NeuN cell densities in lower gray matter (-36%), whereas CD patients had increased densities in upper cortical (+52%) and white matter regions (+65%). For TSC patients, decreased lower gray matter NeuN densities correlated with reduced MRI volumes.

CONCLUSIONS

Patients with tuberous sclerosis without spasms showed microencephaly associated with decreased cortical neuronal densities. In contrast, cortical dysplasia patients without spasms were normocephalic with increased cell densities. This supports the concept that tuberous sclerosis and cortical dysplasia have different pathogenetic mechanisms despite similarities in refractory epilepsy and postnatal histopathology. Furthermore, a history of infantile spasms was associated with reduced cerebral volumes in both cortical dysplasia and tuberous sclerosis patients, suggesting that spasms or their treatment may contribute to microencephaly independent of etiology.

Sex steroids modulate α1-adrenoceptor-stimulated Ca2+ elevation in human cultured prostatic stromal cells

BACKGROUND

Benign prostatic hyperplasia is an age- and androgen-dependent condition of urethral compression caused by prostatic contractility and glandular enlargement. In this study we investigate whether testosterone, dihydrotestosterone and estradiol modulate the ability of human cultured prostatic stromal cells (HCPSCs) to respond to the adrenoceptor agonists, noradrenaline (30 microM) and phenylephrine (100 microM), the protein kinase C activating phorbol ester, phorbol diacetate (PDA, 10 microM), and the L-type Ca(2+) channel activator, (-)-Bay K8644 (Bay K, 10 microM) with elevations of intracellular Ca(2+) ([Ca(2+)](i)).

METHODS

Cells were loaded with the Ca(2+) sensitive fluorophore, FURA-2AM (10 microM) and changes in intracellular Ca(2+) determined before and 8-12 min after ligand addition.

RESULTS

Compared to steroid-free (SF) controls, the incubation of HCPSC with testosterone (30 and 300 pM) significantly increased responses to both noradrenaline and phenylephrine. Responses to Bay K were significantly reduced between 30 nM to 300 pM but responses to PDA were not greatly affected. Compared to SF the addition of estradiol (E(2), 100 pM) did not affect responses to phenylephrine. The concomitant addition of dihydrotestosterone (DHT) and E(2) (to give ratios from 1:1 to 1,000:1) elevated the responses to noradrenaline and phenylephrine at the extreme ranges. Responses to PDA and Bay K generally increased as DHT:E(2) approached unity.

CONCLUSIONS

These results indicate that sex steroids modulate the activities of HCPSCs through the regulation of both receptors and signal transduction processes.

Supramolecular chemistry: functional structures on the mesoscale

Supramolecular chemistry deals with the chemistry and collective behavior of organized ensembles of molecules. In this so-called mesoscale regime, molecular building blocks are organized into longer-range order and higher-order functional structures via comparatively weak forces. As one of the modern frontiers in chemistry, supramolecular chemistry heralds many promises that range from biocompatible materials and biomimetic catalysts to sensors and nanoscale fabrication of electronic devices.

Catalytic Meerwein-Pondorf-Verley reduction by simple aluminum complexes

[reaction: see text] Catalytic MPV reduction was successfully carried out using simple aluminum precatalysts. Alkylaluminum reagents were converted to a low-aggregation aluminum alkoxide that was highly active for the MPV reduction of several carbonyl substrates in high yield (50-99%) using (i)PrOH as the reducing agent. A high degree of cis/trans selectivity was achieved in the reduction of 2-methylcyclohexanone (cis/trans = 20/80) by (i)PrOH. When chiral hydride sources were utilized in the reduction of 2-chloroacetophenone, high enantioselectivity (68-80% ee) was observed.

Imidazolinium salts as catalysts for the ring-opening alkylation of meso epoxides by alkylaluminum complexes

[reaction: see text] Imidazolinium salts and their N-heterocyclic carbene (NHC) derivatives catalyze the alkylation of a variety of meso epoxides in the presence of triethylaluminum (yield = 70-90%), under mild conditions. Imidazolinium salts are better catalysts than their NHC derivatives but can lead to dimerization side reactions under extended reaction time. Preformed NHC.AlEt(3) complexes and Wanzlick-type olefins, which are dimers of free NHCs, are also catalysts for this reaction.

Thrombolytic therapy for adhesion of percutaneous central venous catheters to vein intima associated with Malassezia furfur Infection

OBJECTIVE

To report our experience with thrombolytic agents in the management of two infants with silicone central venous catheters that had adhered to the vein wall as a result of infection with Malassezia furfur.

STUDY DESIGN

Case review of two very low birth weight infants with adherent central venous catheters.

RESULTS

Treatment with urokinase and tissue plasminogen activator facilitated the removal of these catheters without breakage or surgical intervention.

CONCLUSIONS

Thrombolytic agents should be considered as a treatment of adhered catheters, as well as of occluded catheters.

A general high-yield route to bis(salicylaldimine) zinc(II) complexes: application to the synthesis of pyridine-modified salen-type zinc(II) complexes

A general, direct, and high-yield synthesis of bis(salicylaldimine) zinc complexes from the ligands and Et(2)Zn is reported. This synthetic method is particularly valuable, not only because it allows the efficient preparation of salen-type complexes of zinc but also because it can be used to prepare bifunctional pyridine-modified zinc(II) bis(salicylidene) complexes, which are potentially useful compounds for applications in asymmetric catalysis and materials chemistry. The synthesis and complete structural characterization of a new series of pyridine-modified zinc(II) bis(salicylidene) ligands is discussed.

Reconstitution of endogenous interferon a by recombinant interferon in hairy cell leukemia

Recombinant human IFN alpha (rhIFN-alpha) plays an important role in the treatment of hairy cell leukemia (HCL). However, the mechanisms leading to its beneficial effect are not completely clarified, and there is no information on IFN-alpha gene expression in this disease. Therefore, we investigated the pattern of IFN-alpha gene expression and protein production in HCL and their potential regulation by rhIFN-alpha. Blood samples from 10 patients with HCL and 8 healthy donors (HD) were investigated. Expression of IFN-alpha mRNA was assessed by reverse transcription-PCR analysis in peripheral blood mononuclear cells (PBMCs) under basal conditions and on induction with rhIFN-alpha and polyionosinic-polycytidylic acid [poly(I.C)]. IFN-alpha concentrations in plasma and culture supernatants were measured by immunoassays, and intracellular IFN-alpha was evaluated by fluorescence-activated cell sorting analysis. Results showed that, in contrast to blood samples from HDs, freshly isolated PBMCs from un treated HCL patients did not express IFN-alpha mRNA, whereas IFN-alpha transcripts were found in patients who were under rhIFN-alpha therapy Plasma of untreated patients contained no, or extremely low levels of IFN-alpha as compared with plasma of treated patients and HDs. Ex vivo treatment of PBMCs with rhIFN-alpha or poly(I.C) resulted in a remarkable up-regulation of IFN-alpha at the mRNA and protein level. In HCL, however the amounts of IFN-alpha protein remained less than in HD. Inhibition of IFN-alpha transcription was found after exposure of PBMCs to serum fron untreated patients. Finally, a reduced capacity to produce IFN-alpha was found within B- cell, T-cell, and monocyte compartments in HCL patients which could be enhanced by rhIFN-alpha. The results demonstrate the ability, of rhIFN-alpha to up-regulate the expression of IFN-alpha gene and protein production and suggest that priming the production of endogenous IFN-alpha is a critical step in the mechanism of action of rhIFN-alpha in HCL.

Synthesis and characterization of Rhodium(III) dichloro complexes with unsymmetrically bound salen-type ligands

We have synthesized a series of novel octahedral Rh(III) salen-type complexes where the salen ligand is unsymmetrically bound to the Rh(III) dichloride center. This mode of bonding left one intact phenol group coordinating to the rhodium center and has never before been observed in salen-metal chemistry. These remarkably stable complexes possess unique coordination geometry and represent the first time that Rh(III) salen complexes have been successfully isolated from the direct combination of RhCl(3).3H2O and the salen ligand in the absence of a nucleophilic base. The (salen)Rh(III) dichloride complex can be converted to the analogous monochloride complex by reaction with metal carbonate salts.

[Neurologic complications of surgical treatments]

Neurological complications during correction of scoliosis remain a rare but very severe event. Prevention by analysis of risk factors pre-operatively and assessment of complications per-operatively could be done using wake-up test and evoked potential monitoring, to emphasize short term prevention of these complications. A clear information must be given to the patient and his family before such an operation.

Understanding Creutzfeldt-Jakob disease

The "mad cow disease" that decimated cattle in England has brought wide-spread attention to a similar disease in humans, Creutzfeldt-Jakob disease (CJD). This has led to concerns about the transmissibility and contagiousness of the infectious agent from possible CJD patients to health care workers and family members. Despite these worries, the occurrence of CJD in the human population has remained stable over the years at an incidence of about one person per million in the United States population, and increasing to six individuals per million for the older-than-60 age group. This article will review the etiology, clinical manifestations, and potential for transmission of this unusual infectious agent.

Inadequate production of hematopoietic growth factors in hairy cell leukemia: up-regulation of interleukin 6 by recombinant IFN-alpha in vitro

The course of hairy cell leukemia (HCL) is characterized by progressive pancytopenia. The pathogenesis of this phenomenon is still not fully understood. To study if the decrease in hematopoiesis in HCL is accompanied by abnormal concentrations of growth factors, we investigated the production of granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, interleukin 3 (IL-3), interleukin 6 (IL-6), and tumor necrosis factor alpha by peripheral blood mononuclear cells (PBMCs) of eight patients with HCL. The results point to a severe deficiency of production of all cytokines tested as compared to healthy donors. However, enrichment of autologous monocytes by counterflow centrifugation resulted in a marked increase of the levels of granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, IL-6, and tumor necrosis factor alpha. The most pronounced effects were seen with IL-6. Reverse transcription-PCR analysis indicated that pokeweed mitogen, IFN-alpha, and poly(I:C) are capable of inducing the expression of IL-6-specific mRNA in HCL cells. These findings are substantiated on the protein level by immunofluorescence analysis. Incubation of PBMCs with IFN-alpha resulted in a significant increase of intracellular IL-6 in HCL but not in healthy donors. This increase was also seen in hairy cells positive for CD19 and CDllc. Furthermore, IFN-alpha induced the secretion of IL-6 from PBMCs of HCL patients but not healthy donors. In conclusion, our studies with PBMCs from patients with HCL revealed an inadequate supply of hematopoietic growth factors that might, in part, be due to the monocytopenia characteristic for this disease. The findings also indicate that IFN-alpha is capable of inducing the production of IL-6 in the patients' PBMCs as well as in their hairy cells. These data from our in vitro studies support the clinical observation that treatment with IFN-alpha leads to reconstitution of hematopoiesis.

Cloning, expression, and function of TFC5, the gene encoding the B" component of the Saccharomyces cerevisiae RNA polymerase III transcription factor TFIIIB

TFC5, the unique and essential gene encoding the B" component of the Saccharomyces cerevisiae RNA polymerase III transcription factor (TF)IIIB has been cloned. It encodes a 594-amino acid protein (67,688 Da). Escherichia coli-produced B" has been used to reconstitute entirely recombinant TFIIIB that is fully functional for TFIIIC-directed, as well as TATA box-dependent, DNA binding and transcription. The DNase I footprints of entirely recombinant TFIIIB, composed of B", the 67-kDa Brf, and TATA box-binding protein, and TFIIIB reconstituted with natural B" are indistinguishable. A truncated form of B" lacking 39 N-terminal and 107 C-terminal amino acids is also functional for transcription.

Implantable programmable insulin pumps for the treatment of diabetes

Implantable programmable pump systems for insulin delivery to the peritoneal cavity or for intravenous insulin delivery have been recently developed. Thirty-one pumps were implanted in 25 patients between 1987 and 1991. At this writing, 76% of patients had functioning pumps. Ninety-two percent of pumps were functioning at 1 year; 89% at 2 years; and 50% at 3 years. No life-threatening complications, either surgical or metabolic, developed. However, 18 patients required 23 outpatient procedures for maintenance of pump function or for pump removal. Metabolic improvement was evidenced by mean and standard deviation of blood glucose levels and by glycosylated hemoglobin levels.