The Effect of Social Robots on Depression and Loneliness for Older Residents in Long-Term Care Facilities: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

Depression and loneliness are challenges facing older residents living in long-term care facilities. Social robots might be a solution as nonpharmacologic interventions. The purpose of this study was to explore the effects of concrete forms of social robots on depression and loneliness in older residents in long-term care facilities by a systematic review and meta-analysis of randomized controlled trials.

DESIGN

This is a systematic review and meta-analysis.

SETTING AND PARTICIPANTS

Older residents in long-term care facilities.

METHODS

Six electronic databases of PubMed, Embase, Scopus, Web of Science, MEDLINE, and CINAHL plus were searched in August 2023. Random effect models of meta-analyses, subgroup analyses, and meta-regressions were performed for statistical analyses.

RESULTS

After evaluation, 8 studies were selected for both qualitative and quantitative synthesis. Social robot interventions had significant positive effects on decreasing depression and loneliness with large effect sizes. Group-based robot activities had a better effect on improving depression than individual-based robot activities. Longer durations of interventions produced significantly more improvement in depression.

CONCLUSION AND IMPLICATION

Social robots with physical manifestation provide the opportunity for older adults' social engagement and interactions with robots and others. Social robot interventions are recommended for older residents in long-term care facilities to promote psychosocial well-being in daily care routines.

Effects of Accumulated Energy on Nanoparticle Formation in Pulsed-Laser Dewetting of AgCu Thin Films

Ag₅₀Cu₅₀ films were deposited on glass substrates by a sputtering system. Effects of accumulated energy on nanoparticle formation in pulse-laser dewetting of AgCu films were investigated. The results showed that the properties of the dewetted films were found to be dependent on the magnitude of the energy accumulated in the film. For a low energy accumulation, the two distinct nanoparticles had rice-shaped/Ag₆₀Cu₄₀ and hemispherical/Ag₈₀Cu₂₀. Moreover, the absorption spectra contained two peaks at 700 nm and 500 nm, respectively. By contrast, for a high energy accumulation, the nanoparticles had a consistent composition of Ag₆₀Cu₄₀, a mean diameter of 100 nm and a peak absorption wavelength of 550 nm. Overall, the results suggest that a higher Ag content of the induced nanoparticles causes a blue shift of the absorption spectrum, while a smaller particle size induces a red shift.

ATACgraph: Profiling Genome-Wide Chromatin Accessibility From ATAC-seq

Assay for transposase-accessible chromatin using sequencing data (ATAC-seq) is an efficient and precise method for revealing chromatin accessibility across the genome. Most of the current ATAC-seq tools follow chromatin immunoprecipitation sequencing (ChIP-seq) strategies that do not consider ATAC-seq-specific properties. To incorporate specific ATAC-seq quality control and the underlying biology of chromatin accessibility, we developed a bioinformatics software named ATACgraph for analyzing and visualizing ATAC-seq data. ATACgraph profiles accessible chromatin regions and provides ATAC-seq-specific information including definitions of nucleosome-free regions (NFRs) and nucleosome-occupied regions. ATACgraph also allows identification of differentially accessible regions between two ATAC-seq datasets. ATACgraph incorporates the docker image with the Galaxy platform to provide an intuitive user experience via the graphical interface. Without tedious installation processes on a local machine or cloud, users can analyze data through activated websites using pre-designed workflows or customized pipelines composed of ATACgraph modules. Overall, ATACgraph is an effective tool designed for ATAC-seq for biologists with minimal bioinformatics knowledge to analyze chromatin accessibility. ATACgraph can be run on any ATAC-seq data with no limit to specific genomes. As validation, we demonstrated ATACgraph on human genome to showcase its functions for ATAC-seq interpretation. This software is publicly accessible and can be downloaded at https://github.com/RitataLU/ATACgraph.

[Interpreted American College of Radiology TI-RADS classification system of ultrasonography for thyroid nodules in 2017 edition and the experiences in clinical application]

Thyroid nodules are extremely common. Ultrasonography is the most effective imaging modality to diagnose and differentiate thyroid nodules. There are many versions of thyroid image reporting and data system(TI-RADS) evaluated by ultrasound, but some classification system indexes are complicated and clinical application is chaotic. In 2017, the American College of Radiology (ACR) published white papers that introduced a TI-RADS classification system based on conventional ultrasound to reduce the dependence on operators and facilitate communication with physicians. The purpose of the ACR TI-RADS is to establish the risk classification system for managing thyroid nodules and guide the physicians to make professional judgments. The ACR TI-RADS risk classification system is interpreted in this article, including the development, overview and feature categories of ACR TI-RADS, and authors' experiences in clinical application.

Laparoscopic transcystic common bile duct exploration: surgical indications and procedure strategies

BACKGROUND

LTCBDE combined with or without modified techniques is safe and efficacious for the management of gallstones and concomitant, even large, common bile duct (CBD) stones.

METHODS

To describe the surgical indications and procedure strategies of laparoscopic transcystic common bile duct exploration (LTCBDE), a retrospective analysis of 205 patients with concomitant gallstones and CBD stones treated using LTCBDE between June 2008 and June 2015 was performed. Clinical data on disease characteristics, methods for cystic duct incision and CBD stone extraction (with or without laser lithotripsy), and surgical outcomes were collected and reviewed.

RESULTS

CBD stones were successfully cleared in all patients. No patient was converted to choledochotomy or laparotomy. The cystic duct diameter ranged 3-8 mm, and 85 patients with cystic duct diameter ≥ 5 mm. The mean time for CBD stone extraction was 25.3 min, with the operative time ranged from 63 to 170 min. Lithotripsy was used in 74 (36.1%) patients among which 26 patients with cystic duct diameter ≥ 5 mm. Estimated blood loss during surgery was 10-120 ml per patient, and no intra-operative blood transfusions were needed. The mean postoperative hospital stay was 5.1 (range 3-7) days, and postoperative complications developed in seven patients. No bile duct injury, stricture, remnant, recurrent stones, or other adverse events were observed during the mean follow-up of 8 months.

CONCLUSIONS

Based on preoperative MRCP and intra-operative IOC findings about cystic duct diameter, the diameter of CBD, CBD stone size, we summarized and proposed the surgical indications and suitable techniques and strategies during LTCBDE.

A solid-state cation exchange reaction to form multiple metal oxide heterostructure nanowires

Metal oxide nanostructures have been investigated extensively due to their wide range of physical properties; zinc oxide is one of the most promising materials. It exhibits fascinating functional properties and various types of morphologies. In particular, ZnO heterostructures have attracted great attention because their performance can be modified and further improved by the addition of other materials. In this study, we successfully transformed ZnO nanowires (NWs) into multiple ZnO/Al₂O₃ heterostructure NWs via a solid-state cation exchange reaction. The experiment was carried out in situ via an ultrahigh vacuum transmission electron microscope (UHV-TEM), which was equipped with a video recorder. Moreover, we analyzed the structure and composition of the heterostructure NWs by Cs-corrected STEM equipped with EDS. Based on these experimental results, we inferred a cation exchange reaction ion path model. Additionally, we investigated the defects that appeared after the cation reaction, which resulted from the remaining zinc ions. These multiple heterostructure ZnO/Al₂O₃ NWs exhibited excellent UV sensing sensitivity and efficiency.

Progenitor-like cells derived from mouse kidney protect against renal fibrosis in a remnant kidney model via decreased endothelial mesenchymal transition

Introduction

Pathophysiological changes associated with chronic kidney disease impair angiogenic processes and increase renal fibrosis. Progenitor-like cells derived from adult kidney have been previously used to promote regeneration in acute kidney injury, even though it remained unclear whether the cells could be beneficial in chronic kidney disease (CKD).

Methods

In this study, we established a CKD model by five-sixths nephrectomy and mouse kidney progenitor-like cells (MKPCs) were intravenously administered weekly for 5 weeks after establishing CKD. We examined the impact of MKPCs on the progression of renal fibrosis and the potential of MKPCs to preserve the angiogenic process and prevent endothelial mesenchymal transition in vivo and in vitro.

Results

Our results demonstrate that the MKPCs delayed interstitial fibrosis and the progression of glomerular sclerosis and ameliorated the decline of kidney function. At 17 weeks, the treated mice exhibited lower blood pressures, higher hematocrit levels, and larger kidney sizes than the control mice. In addition, the MKPC treatment prolonged the survival of the mice with chronic kidney injuries. We observed a decreased recruitment of macrophages and myofibroblasts in the interstitium and the increased tubular proliferation. Notably, MKPC both decreased the level of vascular rarefaction and prevented endothelial mesenchymal transition (EndoMT) in the remnant kidneys. Moreover, the conditioned medium from the MKPCs ameliorated endothelial cell death under hypoxic culture conditions and prevented TGF-β-induced EndoMT through downregulation of phosphorylated Smad 3 in vitro.

Conclusions

MKPCs may be a beneficial treatment for kidney diseases characterized by progressive renal fibrosis. The enhanced preservation of angiogenic processes following MKPC injections may be associated with decreased fibrosis in the remnant kidney. These findings provide further understanding of the mechanisms involved in these processes and will help develop new cell-based therapeutic strategies for regenerative medicine in renal fibrosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0241-8) contains supplementary material, which is available to authorized users.

Simulation of thermal ablation by high-intensity focused ultrasound with temperature-dependent properties

An integrated computational framework was developed in this study for modeling high-intensity focused ultrasound (HIFU) thermal ablation. The temperature field was obtained by solving the bioheat transfer equation (BHTE) through the finite element method; while, the thermal lesion was considered as a denatured material experiencing phase transformation and modeled with the latent heat. An equivalent attenuation coefficient, which considers the temperature-dependent properties of the target material and the ultrasound diffraction due to bubbles, was proposed in the nonlinear thermal transient analysis. Finally, a modified thermal dose formulation was proposed to predict the lesion size, shape and location. In-vitro thermal ablation experiments on transparent tissue phantoms at different energy levels were carried out to validate this computational framework. The temperature histories and lesion areas from the proposed model show good correlation with those from the in-vitro experiments.

Bioremediation of 1,2-dichloroethane contaminated groundwater: Microcosm and microbial diversity studies

In this study, the effectiveness of bioremediating 1,2-dichloroethane (DCA)-contaminated groundwater under different oxidation-reduction processes was evaluated. Microcosms were constructed using indigenous bacteria and activated sludge as the inocula and cane molasses and a slow polycolloid-releasing substrate (SPRS) as the primary substrates. Complete DCA removal was obtained within 30 days under aerobic and reductive dechlorinating conditions. In anaerobic microcosms with sludge and substrate addition, chloroethane, vinyl chloride, and ethene were produced. The microbial communities and DCA-degrading bacteria in microcosms were characterized by 16S rRNA-based denatured-gradient-gel electrophoresis profiling and nucleotide sequence analyses. Real-time polymerase chain reaction was applied to evaluate the variations in Dehalococcoides spp. and Desulfitobacterium spp. Increase in Desulfitobacterium spp. indicates that the growth of Desulfitobacterium might be induced by DCA. Results indicate that DCA could be used as the primary substrate under aerobic conditions. The increased ethene concentrations imply that dihaloelimination was the dominate mechanism for DCA biodegradation.

Selection for Duration of Fertility and Mule Duck White Plumage Colour in a Synthetic Strain of Ducks (Anas platyrhynchos)

A synthetic strain of ducks (Anas platyrhynchos) was developed by introducing genes for long duration of fertility to be used as mother of mule ducklings and a seven-generation selection experiment was conducted to increase the number of fertile eggs after a single artificial insemination (AI) with pooled Muscovy semen. Reciprocal crossbreeding between Brown Tsaiya LRI-2 (with long duration of fertility) and Pekin L-201 (with white plumage mule ducklings) ducks produced the G0. Then G1 were intercrossed to produce G2 and so on for the following generations. Each female duck was inseminated 3 times, at 26, 29, and 32 weeks of age. The eggs were collected for 14 days from day 2 after AI. Individual data regarding the number of incubated eggs (Ie), the number of fertile eggs at candling at day 7 of incubation (F), the total number of dead embryos (M), the maximum duration of fertility (Dm) and the number of hatched mule ducklings (H) with plumage colour were recorded. The selection criterion was the breeding values of the best linear unbiased prediction animal model for F. The results show high percentage of exhibited heterosis in G2 for traits to improve (19.1% for F and 12.9% for H); F with a value of 5.92 (vs 3.74 in the Pekin L-201) was improved in the G2. Heritabilities were found to be low for Ie (h (2) = 0.07±0.03) and M (h (2) = 0.07±0.01), moderately low for Dm (h (2) = 0.13±0.02), of medium values for H (h (2) = 0.20±0.03) and F (h (2) = 0.23±0.03). High and favourable genetic correlations existed between F and Dm (rg = 0.93), between F and H (rg = 0.97) and between Dm and H (rg = 0.90). The selection experiment showed a positive trend for phenotypic values of F (6.38 fertile eggs in G10 of synthetic strain vs 5.59 eggs in G4, and 3.74 eggs in Pekin L-201), with correlated response for increasing H (5.73 ducklings in G10 vs 4.86 in G4, and 3.09 ducklings in Pekin L-201) and maximum duration of the fertile period without increasing the embryo mortality rate. The average predicted genetic response for F was 40% of genetic standard deviation per generation of selection. The mule ducklings' feather colour also was improved. It was concluded that this study provided results for a better understanding of the genetics of the duration of fertility traits in the common female duck bred for mule and that the selection of a synthetic strain was effective method of improvement.

Synergistic effects of arsenic trioxide combined with ascorbic acid in human osteosarcoma MG-63 cells: a systems biology analysis

OBJECTIVE

To further understand the synergistic mechanism of As2O3 and asscorbic acid (AA) in human osteosarcoma MG-63 cells by systems biology analysis.

MATERIALS AND METHODS

Human osteosarcoma MG-63 cells were treated by As2O3 (1 µmol/L), AA (62.5 µmol/L) and combined drugs (1 µmol/L As2O3 plus 62.5 µmol/L AA). Dynamic morphological characteristics were recorded by Cell-IQ system, and growth rate was calculated. Illumina beadchip assay was used to analyze the differential expression genes in different groups. Synergic effects on differential expression genes (DEGs) were analyzed by mixture linear model and singular value decomposition model. KEGG pathway annotations and GO enrichment analysis were performed to figure out the pathways involved in the synergic effects.

RESULTS

We captured 1987 differential expression genes in combined therapy MG-63 cells. FAT1 gene was significantly upregulated in all three groups, which is a promising drug target as an important tumor suppressor analogue; meanwhile, HIST1H2BD gene was markedly downregulated in the As2O3 monotherapy group and the combined therapy group, which was found to be upregulated in prostatic cancer. These two genes might play critical roles in synergetic effects of AA and As2O3, although the exact mechanism needs further investigation. KEGG pathway analysis showed many DEGs were related with tight junction, and GO analysis also indicated that DEGs in the combined therapy cells gathered in occluding junction, apical junction complex, cell junction, and tight junction.

CONCLUSIONS

AA potentiates the efficacy of As2O3 in MG-63 cells. Systems biology analysis showed the synergic effect on the DEGs.

Underlying mechanism of regulatory actions of diclofenac, a nonsteroidal anti-inflammatory agent, on neuronal potassium channels and firing: an experimental and theoretical study

Diclofenac (DIC), a nonsteroidal anti-inflammatory drug, is known to exert anti-nociceptive and anti-convulsant actions; however, its effects on ion currents, in neurons remain debatable. We aimed to investigate (1) potential effects of diclofenac on membrane potential and potassium currents in differentiated NSC-34 neuronal cells and dorsal root ganglion (DRG) neurons with whole-cell patch-clamp technology, and (2) firing of action potentials (APs), using a simulation model from hippocampal CA1 pyramidal neurons based on diclofenac's effects on potassium currents. In the NSC-34 cells, diclofenac exerted an inhibitory effect on delayed-rectifier K⁺ current (I(KDR)) with an IC₅₀ value of 73 μM. Diclofenac not merely inhibited the I(KDR) amplitude in response to membrane depolarization, but also accelerated the process of current inactivation. The inhibition by diclofenac of IK(DR) was not reversed by subsequent application of either naloxone. Importantly, diclofenac (300 μM) increased the amplitude of M-type K⁺ current (I)(KM)), while flupirtine (10 μM) or meclofenamic acid (10 μM) enhanced it effectively. Consistently, diclofenac (100 μM) increased the amplitude of I(KM) and diminished the I(KDR) amplitude, with a shortening of inactivation time constant in DRG neurons. Furthermore, by using the simulation modeling, we demonstrated the potential electrophysiological mechanisms underlying changes in AP firing caused by diclofenac. During the exposure to diclofenac, the actions on both I(KM) and I(KDR) could be potential mechanism through which it influences the excitability of fast-spiking neurons. Caution needs to be made in attributing the effects of diclofenac primarily to those produced by the activation of I(KM).

The characterization and management of Castleman's disease

OBJECTIVE

Castleman's disease (CD) is a rare disorder of unknown aetiology characterized by lymph node enlargement. This study evaluated the clinical features, diagnosis and outcomes of surgical treatment in patients with CD.

METHODS

The medical records of 10 patients with histologically confirmed CD who underwent surgery between 2003 and 2008 were retrospectively reviewed. Study endpoints were survival and recurrence.

RESULTS

The age of disease onset ranged from 11 to 63 years (median 38 years). Of the 10 patients included in the study, eight were diagnosed with localized (unicentric) CD and two with multicentric CD. All eight patients with localized (unicentric) CD were asymptomatic. Histological evidence indicated the hyaline vascular form of CD in eight patients and the plasmacytic form in the remaining two patients. The primary treatment was complete surgical resection in nine cases, and these patients were alive with no evidence of recurrence or exacerbation at the time of writing (June 2011).

CONCLUSIONS

Localized (unicentric) CD is usually of the hyaline vascular form and complete surgical excision of the tumour allows full recovery in most cases.

Effects of dietary supplementation of Chinese medicinal herbs on polymorphonuclear neutrophil immune activity and small intestinal morphology in weanling pigs

The purpose of this study was to evaluate the effects of dietary Chinese medicinal herbs (CMH) supplementation composed of Panax ginseng, Dioscoreaceae opposite, Atractylodes macrocephala, Glycyrrhiza uralensis, Ziziphus jujube and Platycodon grandiflorum, on the performance, intestinal tract morphology and immune activity in weanling pigs. Two hundred and forty weaned pigs were assigned randomly to four dietary groups including the negative control (basal diet), 0.1% CMH, 0.3% CMH and 0.114% antibiotic (Chlortetracycline calcium Complex, Sulfathiazole and Procaine Penicillin G) supplementation groups for a 28-day feeding trial. Results indicated that both CMH supplementation groups had a better gain and feed/gain than control group (CT) during the first 2 weeks of the experimental period. The 0.3% CMH had a significant decrease in the diarrhoea score in first 10 days of experimental period when compared with other groups. The CMH supplementation groups had a higher villous height, increased lactobacilli counts in digesta of ileum and decreased coliform counts in colon compared with CT. The immune activities of polymorphonuclear leucocytes (PMNs), including the respiratory burst and Salmonella-killing ability, were significantly enhanced in CMH supplementation groups at day 7 of experiment period. The CMH and antibiotic supplementations increased the nutrient digestibility such as dietary dry matter, crude protein and gross energy in weanling pigs. In conclusion, the dietary CMH supplementation improved intestinal morphology and immune activities of PMNs, thus giving rise to nutrient digestibility and reduce diarrhoea frequency in weanling pigs.

Experimental and simulation studies on the mechanisms of levetiracetam-mediated inhibition of delayed-rectifier potassium current (KV3.1): contribution to the firing of action potentials

Levetiracetam (LEV) is an S-enantiomer pyrrolidone derivative with established antiepileptic efficacy in generalized epilepsy and partial epilepsy. However, its effects on ion currents and membrane potential remain largely unclear. We investigated the effect of LEV on differentiated NG108-15 neurons. In these cells treated with dibutyryl cyclic AMP, the expression level of the K(V)3.1 mRNA was elevated. With the aid of patch clamp technology, we found that LEV could suppress the amplitude of delayed rectifier K(+) current (I(K(DR))) in a concentration-dependent manner with an IC(50) value of 37 microM. LEV (30 microM) shifted the steady-state activation of I(K(DR)) to a more positive potential by 10 mV, without shifting the steady-state inactivation of I(K(DR)). Neither Na(+), nor erg (ether-a-go-go-related)-mediated K(+) and ATP-sensitive K(+) currents were affected by LEV (100 microM). LEV increased the duration of action potentials in current clamp configuration. Simulation studies in a modified Hodgkin-Huxley neuron and network unraveled that the reduction of slowly inactivating I(K(DR)) resulted in membrane depolarization accompanied by termination of the firing of action potentials in a stochastic manner. Therefore, the inhibitory effects on slowly inactivating I(K(DR)) (K(V)3.1-encoded current) may constitute one of the underlying mechanisms through which LEV affect neuronal activity in vivo.

Cognitive deficits in multiple system atrophy correlate with frontal atrophy and disease duration

BACKGROUND AND PURPOSE

Dementia remains an exclusion criterion in diagnosing multiple system atrophy (MSA). This study aimed to determine the cognitive changes and brain atrophy patterns in the Parkinsonian (MSA-P) and cerebellar (MSA-C) variants of MSA.

METHODS

Voxel-based morphometry (VBM) of magnetic resonance imaging (MRI) and neuro-psychological tests were applied to 10 MSA-C and 13 MSA-P patients, and compared to 37 age-matched controls. Correlation analyses were performed between cognitive test results and morphometric data extracted from the VBM data.

RESULTS

In neuro-psychological testing, the 23 MSA patients scored lower in the Stroop interference test and took longer in the trail-making test as compared with the controls, whereas MSA-C performed worse than MSA-P in the memory scores, Stroop test, and time to complete the trail-making test. MSA, as a group, showed atrophy in the cerebellum, insular cortex, fusiform gyrus, inferior orbito-frontal gyrus, superior temporal gyrus, and caudate nucleus. Memory scores correlated well with pre-frontal lobe atrophy but not in the insular area.

CONCLUSION

In conclusion, although dementia is not a typical presenting feature of MSA and is regarded as a sub-cortical movement disorder, frontal atrophy, cognitive changes, and dementia are identifiable as MSA progresses.

A travelling wave dielectrophoretic pump for blood delivery

The travelling wave dielectrophoretic pump studied here is essentially a rectangular straight micro-channel with an electrode array on part of its wall, and operated under an ac voltage with phase shift at neighbouring electrodes. The travelling wave dielectrophoretic force drives the cells, which drag the plasma, and after some sophisticated interaction between conventional dielectrophoresis, travelling wave dielectrophoresis and fluid mechanics, the whole blood is delivered. The pump was fabricated using MEMS techniques and studied in details for different parameters. It is found that the pumping velocity is maximized at an intermediate frequency around 20-30 MHz (varies with phase shift), and at an intermediate channel height at about 40 microm. The quasi-static average cell velocity can reach 15 microm s(-1) for a pump with 1 mm length and 16 electrodes (total array length 465 microm) operated at 5 V and 20 MHz with 90 degrees phase shift.

The effects of soygerm extracts on blood lipoproteins, antioxidative capacity and urinary estrogen metabolites in postmenopausal women on hormone therapy

OBJECTIVE

To evaluate the effects of soygerm isoflavones extracts on blood lipoproteins, antioxidative capacity and urinary estrogen metabolites in postmenopausal women who receive hormone therapy (HT).

METHOD

Thirty-nine volunteers receiving HT were recruited, and 33 completed the study. All subjects received 6 g of soygerm extracts per day for 4 weeks. Blood and urine samples were collected for study at the beginning and at the end of study.

RESULT

Plasma HDL-C levels increased markedly with significant decreases of plasma LDL-C/HDL-C ratio and LDL-TG levels. The lag time of conjugated dienes formation prolonged for 9.9% and thiobarbituric acid reactive substances production in copper-catalyzed oxidation of LDL decreased. The differences were statistically significant. Urinary ratio of 2-OHE(1) to 16alpha-OHE(1) increased without statistical significance.

CONCLUSION

Soygerm extracts may improve serum lipid profile in postmenopausal Taiwanese women who receive HT, and probably provide a favorable effect on estrogen metabolism.

Expressed transcripts associated with high rates of egg production in chicken ovarian follicles

The purpose of this study was to characterize differentially expressed transcripts associated with varying rates of egg production in Taiwan country chickens. Ovarian follicles were isolated from two strains of chicken which showed low (B) or high (L2) rates of egg production, then processed for RNA extraction and cDNA library construction. Three thousand and eight forty clones were randomly selected from the cDNA library and amplified by PCR, then used in microarray analysis. Differentially expressed transcripts (P<0.05, log(2)> or = 1.75) were sequenced, and aligned using GenBank. This analysis revealed 20 non-redundant sequences which corresponded to known transcripts. Eight transcripts were expressed at a higher level in ovarian tissue prepared from chicken strain B, and 12 transcripts were expressed at a higher level in L2 birds. These differential patterns of expression were confirmed by semi-quantitative RT-PCR. We show that transcripts of cyclin B2 (cycB2), ferritin heavy polypeptide 1 (FTH1), Gag-Pol polyprotein, thymosin beta4 (TB4) and elongation factor 1 alpha1 (EEF1A1) were enriched in B strain ovarian follicles. In contrast, thioredoxin (TXN), acetyl-CoA dehydrogenase long chain (ACADL), inhibitor of growth family member 4 (ING4) and annexin II (ANXA2) were expressed in at higher levels in the L2 strain. We suggest that our approach may lead to the isolation of effective molecular markers that can be used in selection programs in Taiwan country chickens.

Non-ketotic hyperglycaemia-related paroxysmal bilateral hand paraesthesia misdiagnosed as diabetic neuropathy

Non-ketotic hyperglycaemia (NKH)-related partial seizure disorders are not uncommon in clinical practice but still deserve attention as they significantly affect neurologic outcome if unnoticed. The atypical presentation of sensorimotor symptoms can be seen in this setting, with paroxysmal character as the rule. Atypical manifestations could cause confusion and might lead to improper diagnosis and treatment. We report a case of inadequately controlled diabetes mellitus and NKH presenting as paroxysmal paraesthesia of both hands, which was misdiagnosed as diabetic neuropathy.

Female-specific DNA sequences in geese

1. The OPAE random primers (Operon Technologies, Inc., CA) were used for random amplified polymorphic DNA (RAPD) fingerprinting in Chinese, White Roman and Landaise geese. One of these primers, OPAE-06, produced a 938-bp sex-specific fragment in all females and in no males of Chinese geese only. 2. A novel female-specific DNA sequence in Chinese goose was cloned and sequenced. Two primers, CGSex-F and CGSex-R, were designed in order to amplify a 912-bp sex-specific polymerase chain reaction (PCR) fragment on genomic DNA from female geese. 3. It was shown that a simple and effective PCR-based sexing technique could be used in the three goose breeds studied. 4. Nucleotide sequencing of the sex-specific fragments in White Roman and Landaise geese was performed and sequence differences were observed among these three breeds.

Implementation of a short-tip tapping-mode tuning fork near-field scanning optical microscope

We present the implementation of a short-tip tapping-mode tuning fork near-field scanning optical microscope. Tapping frequency dependences of the piezoelectric signal amplitudes for a bare tuning fork fixed on the ceramic plate, a short-tip tapping-mode tuning fork scheme and an ordinary tapping-mode tuning fork configuration with an 80-cm optical fibre attached are demonstrated and compared. Our experimental results show that this new short-tip tapping-mode tuning fork scheme provides a stable and high Q factor at the tapping frequency of the tuning fork and will be very helpful when long optical fibre probes have to be used in an experiment. Both collection and excitation modes of short-tip tapping-mode tuning fork near-field scanning optical microscope are applied to study the near-field optical properties of a single-mode telecommunication optical fibre and a green InGaN/GaN multiquantum well light-emitting diode.

A study on grafting and characterization of HMDI-modified calcium hydrogenphosphate

It is known that the organic molecules can provide an effective means to manipulate the surface properties of the biodegradable ceramic. There are two ways to modify the surface of the biodegradable ceramic by organic molecules. The first one is through surface adsorption but organic molecules will easily be washed out in the physiological environment. The second approach is to graft organic molecules through covalent bond to the hydroxyl groups that are available on the surface of the ceramics. Isocyanate group has been reported as a coupling agent for hydroxyapatite and organic molecule. The studies showed that the isocyanate could react with hydroxyl groups of hydroxyapatite and form a covalent bond between isocyanate and hydroxyapatite. In the study, hexamethylene diisocyanate (HMDI) was used as coupling agent and calcium hydrogenphosphate (CaHPO4, CHP) was the candidate ceramic. CHP will react with HMDI at the temperature of 20 degrees C, 30 degrees C, 40 degrees C, 50 degrees C, 60 degrees C, and 70 degrees C for 4h. Dibutyltin dilaurate and hydroquinone were used as catalyst and inhibitor, respectively. The effect of reaction temperature on the grafted yield will be described. The linkage between CHP and HMDI will be characterized by DTA, TGA, FTIR, XRD, and 31P, 13C liquid state NMR. From the results, we successfully modified the surface of CHP with coupling agent of HMDI. The grafted yield of HMDI on CHP was increasing with the reaction temperature. The best temperature for CHP modified by HMDI is around 50 degrees C. The linkage between HMDI and the surface of CHP is a urethane linkage as CHP-O-CO-NH-(CH2)6-N=C=O. After further treatment, the terminal group of CHP treated with HMDI (MCHP) will be converted into a primary amine group as the formula of CHP-O-CO-NH-(CH2)6-NH2. If reaction temperature is 60 degrees C, long extension chain will occur with a urea linkage between the isocyanate groups as the formula of CHP-O-CO-NH-(CH2)6-(NH-CO-NH-(CH2)6)n-NH2. At reaction temperature higher than 60 degrees C, the HMDI will become prepolymerized forms in solution. The prepolymerized forms such as allophanate, biuret, uretidione and urea linkage will turn the solution into gel type mixture, which will lead to low grafted yield of HMDI on CHP. When MCHP prepared at the temperature 20 degrees C, there is no evidence of long extension but the grafted yield is the lowest only 0.9 wt% around.

Recurrent hypertensive intracerebral hemorrhage among Taiwanese

Hypertensive intracerebral hemorrhage (HICH) was once thought to be a one-time event with very rare recurrence, but recent studies have revealed that the recurrent hemorrhage due to hypertension is not unusual. The purpose of this study was to determine the clinical characteristics of HICH among Taiwanese. From June 1988 to December 1999, 1421 HICH patients were admitted to our hospital. Among them, 68 patients (4.8%) had recurrent HICH. We reviewed their medical records and computed tomographic findings. There were 46 males and 22 females (M/F = 2.1) with a mean age of 59.9 +/- 11.9 years at the onset of the second hemorrhage. The median interval between the first two hemorrhages was 22.5 months (range: 1-107 months). Most of the recurrence was within two years of the first hemorrhage (within 1 year in 27.9%, within 1-2 years in 25%). The location of the second hemorrhage was typical for HICH (putamen in 44.1%, thalamus in 33.8%, cerebellum in 5.9%, pons in 4.4%, and caudate nucleus in 1.5%) except for 7 patients (10.3%) who had lobar hematoma. Forty-nine patients (72%) had both hemorrhages located in the supratentorium and in most of them (40 patients) the recurrent HICH occurred contralaterally to the first one. Putaminal-thalamic pattern was the most common (23.5%), followed by the putaminal-putaminal pattern (20.6%). The mortality rate of the second HICH was 17.6%. Seven patients (10.3%) experienced more than 2 episodes of hemorrhages. This report found that the recurrent HICH was not rare among Taiwanese. A substantial proportion (19.1%) of recurrence was after 5 years. The male predominance and risk factor for recurrent HICH require further study.

[Quantitative detection of HER-2 oncogene amplification in primary hepatocellular carcinoma using dual FISH technique and its clinical significance]

To investigate the frequency of HER-2 oncogene amplification in primary hepatocellular carcinoma (HCCs) and its relationships with clinicopathological parameters and prognosis, 42 surgical samples from patients with primary HCCs were detected for their HER-2 oncogene amplification by dual FISH technique, and then the correlations between HER-2 amplification and clinicopathological characteristics and prognosis were analyzed statistically. HER-2 oncogene amplification was detected in 9 of 42 (21.4%) primary HCCs, including 4 (9.5%) cases with high copy (HC) and 5 (11.9%) ones with low copy (LC). HER-2 amplification was associated significantly with postoperative survival time of HCC patients examined (P = 0.046) and the presence of HER-2 gene amplification showed a trend toward a correlation with tumor size (P = 0.085), but wasn't relative to sex, age, AFP level, HBV infection, postoperative relapse and clinical staging of HCC patients tested (P > 0.05). On the other hand, gain of the HER-2 oncogene copy was examined in 31 of 42(73.8%) primary HCCs, consisting of 9 (21.4%) cases with HER-2 amplification and 22(52.4%) ones with aneusomy 17/polysomy 17. There weren't significant relationships between gain of HER-2 oncogene copy and, HCC patient's sex, tumor size, clinical staging, postoperative relapse and survival time (P > 0.05), but gain of HER-2 oncogene copy correlated significantly to patients' age, AFP level and HBV infection (P < 0.05). The study indicated that there were a lower frequency of HER-2 oncogene amplification and a higher frequency of aneusomy 17/polysomy 17 in primary HCCs and that HER-2 oncogene amplification activation might be involved in the development and progression of a subset of HCCs, and seemed to be a valuably independent prognosis factor predicting postoperative poorer survival for patients with HCC.

Osteogenic evaluation of glutaraldehyde crosslinked gelatin composite with fetal rat calvarial culture model

The cytotoxicity of the synthetic bone substitute composed of tricalcium phosphate and glutaraldehyde crosslinked gelatin (GTG) were evaluated by osteoblast cell culture. In a previous study, the GTG composites were soaked in distilled water for 1, 2, 4, 7, 14, 28, and 42 days, and then the solutions (or extracts) were cocultured with osteoblasts to evaluate the cytotoxicity of GTG composites by alive cell counting. In this study, the extracts were cocultured with the osteoblasts; thereafter, the concentration of transforming growth factor-beta (TGF-beta1) and prostaglandin E2 (PGE2) in the medium was analyzed to strictly reflect the biological effects of GTG composites on the growth of osteoblasts. In order to investigate the osteoconductive potential of the GTG composites on new bone formation in a relative short term, a model of neonatal rat calvarial organ culture was designed prior to animal experiments. Three experimental materials of 4, 8, and 12% GTG composites were evaluated by fetal rat calvarial organ culture for their ability for bone regeneration. Deproteinized bovine and porcine cancellous bone matrixes were used as the controlled materials. All the organ culture units were maintained in cultured medium for 5 weeks. Following the culture period, the morphology of tissue was observed under an optical microscope, and the quantitative evaluation of the new generation bone was determined by using a semiautomatic histomorphometeric method. Except in the initial 4 days, the concentration of TGF-beta1 of 4% and 8% GTG composites was higher than that of the blank group for all the other experimental time periods. The PGE2 concentration for 4% and 8% GTG composites was lower than that of the blank group. It revealed that the 4% and 8% GTG composites would not lead to inflammation and would promote osteoblast growth. The morphology and activity of the osteoblasts were not transformed or changed by the 2 GTG composites. For the 12% GTG composite, the performance of the in vitro condition was inferior to the blank group and the other 2 GTG composites. Although the concentration of TGF-beta1 and PGE2 was gradually back to normal after 14 days, the morphology of the osteoblasts was abnormal with features such as contracted cytoplast structures. The osteoblast was damaged perhaps in the initial stage. We suggested that the 4% and 8% GTG composites should be soaked in distilled water at least for 4 days before medical applications. The 12% GTG composite and the composites with a concentration of glutaraldehyde solution higher than 12% were not recommended as a medical prostheses in any condition. The fetal rat calvaria culture also showed the same results with the analysis of TGF-beta1 and PGE2. From the study, we could predict the results of animal experiments in the future.

Biogeography and origin of Lilium longiflorum and L. formosanum (Liliaceae) endemic to the Ryukyu Archipelago and Taiwan as determined by allozyme diversity

Allozyme diversity on 13 isozyme loci was investigated for two bulbous species, Lilium longiflorum and L. formosanum, endemic to the subtropical archipelago of continental origin located in East Asia. Degrees of allozyme variability and divergence for L. longiflorum were very high for insular endemic species, indicating relatively longtime persistence of the present widespread distribution across many islands in this phenotypically little-changed species. Lilium formosanum exhibited rather lower variability and divergence than did L. longiflorum and was genetically close to the southern peripheral populations of L. longiflorum with 0.978 as its highest genetic identity value. Combined with other biological and insular geohistorical information, our results suggest that L. longiflorum was established around the end of the Pliocene when the current distribution area was still a continuous part of the ancient Asian continent, and L. formosanum was derived from southern populations of L. longiflorum around the late Pleistocene when the mainland of Taiwan was completely separated from the adjacent islands and the main continent. Depauperization of allozyme variability in some L. longiflorum populations was found on islands with lower altitudes. This reflects bottleneck effects after the complete or almost complete submergence of such low islands during the archipelago's development.

Preparation and characterization of surface-modified calcium hydrogenphosphate by hexamethylene diisocyanates

Isocyanate group has been reported as a coupling agent of hydroxyapatite and polymers. The studies showed that the isocyanate would react with hydroxyl groups of hydroxyapatite and form a covalent bond between isocyanate and hydroxyapatite. In the study, hexamethlene diisocyanate (HMDI) was used as coupling agent. Calcium hydrogen-phosphate (CaHPO4, CHP) powders was the candidate ceramic due to higher content of hydroxyl group, which would react with HMDI at the temperature of 30, 40, 50, 60, and 70 degrees C for 4 hours. Dibutyltin dilaurate and hydroquinone were used as catalyst and inhibitor, respectively. The product was analyzed by DTA, TGA, FTIR, XRD, 13C solid state NMR and 31P, 13C liquid state NMR. From the results, we could prove the surface of calcium hydrogen-phosphate has been successfully modified. The largest amount (5.6 wt%) of HMDI could be grafted on the surface of CHP when reacted at 50 degrees C for 4 hours. Some chain extension could be observed and their structure would also be described in the research.

Ki67 labelling index correlates with stage and histology but not significantly with prognosis in thymoma

AIMS

There have been several cell kinetic studies of thymoma, but the effectiveness of using Ki67 antibody as a tool to measure proliferative activity in this tumour was rarely evaluated. We carried out an immuno-histochemical study using this antibody to assess the clinicopathological correlation and the prognostic significance of this technique.

METHODS AND RESULTS

Ninety-one cases of thymoma were collected. Double immunostaining with Ki67 and cytokeratin KL-1 antibodies was performed on paraffin sections. Ki67 labelling index (LI) was expressed as a percentage of Ki67 immunopositive nuclei by counting at least 1000 epithelial cells. The LIs were correlated with stages, histological subtypes based on both Lattes-Bernatz and Müller-Hermelink-Kirchner classifications, and length of survival. There were statistically significant differences of LIs between stage I and stage III and between stage I and stage IV tumours. Histologically, statistically significant differences were identified between predominantly epithelial thymoma and every other subtype of the Lattes-Bernatz classification and between well-differentiated thymic carcinoma and medullary or mixed thymomas of the Müller-Hermelink-Kirchner classification. Regarding the prognostic implication of Ki67 LI, although there appeared a trend that patients with tumours of higher LIs had slightly worse survival, the difference was not statistically significant in both univariate and multivariate survival analyses.

CONCLUSIONS

We have demonstrated the proliferative potential in thymoma is associated with stage and histology. However, its clinical usefulness is limited on account of the overlap of LIs and lack of prognostic significance.

Biological effects and cytotoxicity of the composite composed by tricalcium phosphate and glutaraldehyde cross-linked gelatin

The purpose of this study was to prepare and evaluate the feasibility and cytocompatibility of a composite (GTG) as a large defect bone substitute. The composite is combined with tricalcium phosphate ceramic particles and glutaraldehyde cross-linked gelatin. Gelatin had been reported as an adhesive and biocompatible binder that could accelerate the recovery of damaged soft tissue, but the effects of gelatin when acting on the bone tissue is not clear. Thus, it is necessary to determine if the substances released from the GTG composite can facilitate the growth of bone cells. The substances released from the GTG composites after being soaked in deionized distilled water were analyzed by gas chromatography (GC), ultraviolet and visible absorption spectroscopy (UV-VIS), and inductive-coupled plasma-atomic emission spectrometry (ICP-AES). The cytotoxicity of the GTG composites was assessed by coculture of rat osteoblasts in vitro. Extracts were obtained by soaking the GTG composites in deionized distilled water for 1, 2, 4, 7, 14, 28 and 42 d. The extract mixed with complete medium in a ratio of 1:1 was added into the cell culture wells containing 1 x 10(4) cells ml(-1) osteoblasts. After culturing for 2 days, the cells attached to the surface of wells were trypsinized and the number calculated by the Neubauer counting-chamber under the optical microscope. Finally, three samples in each GTG group were examined by scanning electron microscopy (SEM) to observe the morphology of the osteoblasts attached to the surfaces of GTG composites. The examinations of osteoblasts cocultured with the developed GTG composites were used to decide the ideal concentration of glutaraldehyde as a cross-linking agent. The results of extracts cocultured with osteoblasts showed that the extracts obtained from the 2, 4 and 8% glutaraldehyde cross-linked GTG composites would inhibit the growth of osteoblasts in the first 4 soaking days. During the 4-7 days soaking, the cell numbers quickly increased with the soaking time, thereafter, the cell numbers almost reached a constant value. In the analyses of substances released from the GTG composites, it was found that the gelatin and calcium were gradually released from the GTG composites, which were supposed to be nutritious for the growth of the osteoblast. The results of osteoblasts cocultured with the GTG composites showed that the concentration of glutaraldehyde used as a cross-linking agent should be lower than 8%. Compared to the GTF (composite combined with tricalcium phosphate ceramic particles and formaldehyde cross-linked gelatin), GTG composites were much suitable for a large defect bone substitute in the near future.

A seroepidemiologic study of Chlamydia pneumoniae, Chlamydia trachomatis and Chlamydia psittaci in different populations on the mainland of China

To evaluate and compare the prevalence of antibodies to 3 chlamydial species in various populations on the mainland of China, the MIF test was used to detect both serum IgG and IgM antibodies to these species in the normal population (n = 711), in poultry workers (n = 51), in female prostitutes (n = 106), in patients attending the sexually transmitted diseases clinic (n = 98), and in adult patients with pneumonia and bronchitis (n = 108). In the normal population, IgG antibodies against C. pneumoniae, C. trachomatis and C. psittaci were present in 61.5%, 9.3%, and 3.5%, respectively, and increasing with age. Prevalence and geometric mean titers (GMT) of IgG antibodies to C. trachomatis in prostitutes (54.7%) and female (55%), but not male (15.4%) sexually transmitted disease patients were significantly higher than in the normal adult female population. The prevalence indicating both previous and recent C. psittaci infections in poultry workers was no higher than in the others. The prevalence of IgG antibodies and GMT to C. pneumoniae in patients with pneumonia and bronchitis was not statistically higher than in the normal adult population. Evidence of cross-reactivities in the MIF test between different species was found in both prevalence and GMT. Serum IgM antibodies were usually absent in patients who met the serological criteria of recent C. pneumoniae infection, indicating that most of them could be considered as reinfections. On the basis of our survey, acute antibodies to C. pneumoniae by the MIF test, if they are detected, may be valuable in the diagnosis of recent C. pneumoniae infections.

Pollution by PCDDS and PCDFS in sediment from freshwater fish culture ponds near incineration sites for metal reclamation in Wan-Li, Taiwan, Republic of China

Sediment samples from nine culture ponds for freshwater fish at and near waste incineration sites for metal reclamation in Wan-Li, southern Taiwan, Republic of China were analyzed for PCDDs and PCDFs by HRGC-HRMS. Four of nine samples were heavily polluted by PCDDs and PCDFs, indicating the latter to be dominant. The total TEQ concentrations of PCDDs and PCDFs in the four samples were in the range of 257 to 12200 pg/g dry weight. In addition, the levels corresponded to those of surface soil samples from the same waste combustion areas.

Studies on the concentrations of arsenic, selenium, copper, zinc and iron in the hair of blackfoot disease patients in different clinical stages

Flame atomic absorption spectrophotometric methods were developed for, arsenic, selenium, copper, zinc and iron in hair samples. Data from blackfoot disease patients at five clinical stages were compared with those from healthy controls. The copper and zinc concentrations showed only slight differences in all clinical stages, which indicated the less relation to blackfoot disease. The decrease of selenium and iron in all stages was attributed to the antagonistic effect of arsenic; arsenic increased in the first and second stages, but decreased in the later stages. The decrease of selenium and iron during the progression of the disease is thought to be due to persistence of the antagonistic effect of arsenic in the initial stages, so that very low concentrations of selenium are found in the advanced stages, despite the later decrease of arsenic. There was also a progressive decrease of iron with advance of the disease, and the later stages also showed a decrease in haemoglobin. It was shown that arsenic is a major cause of blackfoot disease, and that it antagonises selenium and iron, which decreased in the advanced clinical stages of the disease.

Studies on the concentration of arsenic, selenium, copper, zinc and iron in the blood of blackfoot disease patients in different clinical stages

Flame atomic absorption spectrophotometric methods were developed for the determination of zinc, copper, arsenic, iron and selenium in blood samples. Data from blackfoot disease patients in five clinical stages were compared with those from healthy controls. Copper concentrations were the same for all clinical stages. Arsenic increased in the initial three stages but decreased thereafter, although arsenic was previously considered to be the major causative agent of the disease. The decrease of arsenic in the later stages was attributed to the antagonistic effect of selenium, and the decrease of iron during the progress of the disease is thought to be due to the antagonistic effect of arsenic in the initial stages and the loose of haemoglobin in the later stages.

Trace elements in hair of Blackfoot disease

Blackfoot disease is a peripheral vascular disease resulting in gangrene of the lower extremities. Though extensive epidemiological study has implicated that high arsenic content in artesian well water of the endemic area bears some important connection with the disease, the etiology of the disease is still unknown. In this study, attention is paid to multielement determination in order to find out whether the trace elements in hair of Blackfoot disease patients are different from those of the controls. Experimental results indicate that the concentrations of As and Se in hair of patients are significantly higher than those of the controls, but Ca and Zn are significantly lower than those of the controls. The possible connection of these elements with the etiology of the disease is discussed.

[Stress analysis with a laser microscope analyzer for acrylic base resin]

Acrylic resin are applied widely as a denture resin,its residual stress is closely related with aging and mechanical properties of denture resin.The authors tested the stress level of the base resin with a laser microscope stress analyzer in the study.The results indicated that there was not statistical differences between two curing methods is in water bath or under pressure.The residual stress in base resin can be concentrated at the area near to clasp wire which was embedded in base resin for reinforcing strength of denture base.The vibration caused by grind with stone wheel or impact in disc lasting with a hammer may increase the stress level in base.The authors pointed out some methods for reducing residual stress resin.

Simultaneous determination of Zn, Cd, Pb, and Cu in urine of patients with blackfoot disease using anodic stripping voltammetry

Blackfoot disease (BFD) is an endemic peripheral vascular disorder resulting in gangrene of the lower extremities, especially the feet, among residents in a limited area on the southwest coast of Taiwan. In the present study, the concentrations of zinc, cadmium, lead, and copper in urine of BFD patients with matched normal controls are investigated by differential pulse anodic stripping voltammetry (DPASV) on a hanging mercury drop electrode (HMDE). The analytical results indicate that urinary copper, cadmium, and lead of the BFD patients are significantly higher than those of the controls. In addition, the patients showed a significantly lower concentration of zinc in the urine than the normal controls. The possible connection of these elements with the etiology of the disease is discussed.

[Effects of furazolidone on brain monoamines in the treatment of peptic ulcer]

The purpose of this study was to investigate the protective role of furazolidone against the formation of duodenal ulcer induced by cysteamine and the effect of furazolidone on NE, DA and 5-HT concentrations in various brain regions (telencephalon, diencephalon and brainstem). The results indicated that one dose of cysteamine (280 mg/kg) produced 90-92% ulceration with no mortality within the first 24 hours, whereas cysteamine plus furazolidone significantly decreased the duodenal ulceration from 90% to 0. Using a sensitive spectrofluorimetric method, we found that cysteamine markedly diminished the NE levels in all regions but the DA level only in telencephalon. Meanwhile, cysteamine plus furazolidone increased the DA level in the same region. This suggested that the protective role of furazolidone against the formation of duodenal ulcer induced by cysteamine in rat may be related to increased DA level in telencephalon.

A fluorescence immunoassay for soluble antigens employing flow cytometric detection

A "sandwich" fluorescence immunoassay is described which does not require the physical separation of bound from free label. Antibody coated microspheres, sample and fluorescent antibody are reacted together as in a conventional 'sandwich' immunoassay except that separation and washing steps are omitted. After the reaction is completed, the suspension is introduced directly into a flow cytometer equipped with a laser light source and both fluorescent and scattered light detection capabilities. By gating fluorescence light accumulation on scattered light pulses, particles associated fluorescence may be selectively measured. The system was evaluated in a model immunoassay for human immunoglobulin (hIgG), employing anti-hIgG coated microspheres (1--5 micrometer and 40--50 micrometer polyacrylamide beads and 30--40 micrometer dextran beads), fluorescein-labeled rabbit anti-hIgG and a Spectrum III flow cytometer. Sensitivities of 10 ng/ml and intra-assay precisions of 2--10% were achieved in a serum matrix. The approach potentially provides a general nonseparation immunoassay format for quantitatively measuring both small and large molecular weight soluble antigens, as well as cell surface antigens.

Low stereoselectivity in methylacetylene and cyclopropene reductions by nitrogenase

The stereochemistry of reductions catalyzed by nitrogenase in 2H2O has been investigated by using allene, methylacetylene, and cyclopropene as substrates. Deuterium labeling patterns in the reduction products were determined by mass spectroscopy, infrared spectroscopy, 2H-decoupled 220-MHz 1H NMR, and 1H-decoupled 30.7-MHz 2H NMR. Reduction of allene gave pure [2,3-2H2]propene. Reduction of methyl acetylene gave a 1.8:1.0 mixture of [cis- and [trans-1,2-2H2]propene. (Similar reduction of acetylene reportedly gave virtually all [cis-1,2-2H2]ethylene.) Reduction of cyclopropene gave [cis-1,2-2H2]cyclopropane and a mixture of [2H2]propenes. The major propene 2H2 isomers formed were [trans-1,3-2H2]-propene (approximately 2), [cis-1,3-2H2]propene (approximately 1) and [2,3-2H2]propene (approximately 1). Cyclopropene appears to be unique as a nitrogenase substrate in that it simultaneously undergoes parallel reductions, one of which proceeds with high stereoselectivity while the other proceeds with low stereoselectivity. The weakly selective stereochemistry observed in these reductions is not consistent with a completely concerted dual proton-dual electron transfer mechanism. The results provide a basis to probe stereochemical effects in nitrogenase and in biomimetic model systems.