Development of a quasi-collimated UV LED backlight for producing uniform and smooth 3D printing objects

3D printing techniques have great potential in the direct fabrication of microfluidic and many kinds of molds, such as dental and jewelry models. However, the resolution, surface roughness, and critical dimension uniformity of 3D printing objects are still a challenge for improvement. In this article, we proposed a 405nm light emitting diode (LED) backlight module based on stacks of structured films, and the full width half maximum (FWHM) of the angular distribution of this module is reduced to less than ± 15°. Compared with the commercial lens array optical module, the ten points intensity uniformity of an 8.9" build area is improved from 56% to 80%. Moreover, we found that the surface roughness and the sharpness of the edge of the printing objects are also obviously improved by our novel quasi-collimated LED backlight module. These features give us a promising way for the application of microfluidics and micro-optics components in the future.

The QseEF Two-Component System-GlmY Small RNA Regulatory Pathway Controls Swarming in Uropathogenic Proteus mirabilis

Bacterial sensing of environmental signals through the two-component system (TCS) plays a key role in modulating virulence. In the search for the host hormone-sensing TCS, we identified a conserved qseEGF locus following glmY, a small RNA (sRNA) gene in uropathogenic Proteus mirabilis. Genes of glmY-qseE-qseG-qseF constitute an operon, and QseF binding sites were found in the glmY promoter region. Deletion of glmY or qseF resulted in reduced swarming motility and swarming-related phenotypes relative to the wild-type and the respective complemented strains. The qseF mutant had decreased glmYqseEGF promoter activity. Both glmY and qseF mutants exhibited decreased flhDC promoter activity and mRNA level, while increased rcsB mRNA level was observed in both mutants. Prediction by TargetRNA2 revealed cheA as the target of GlmY. Then, construction of the translational fusions containing various lengths of cheA 5′UTR for reporter assay and site-directed mutagenesis were performed to investigate the cheA-GlmY interaction in cheA activation. Notably, loss of glmY reduced the cheA mRNA level, and urea could inhibit swarming in a QseF-dependent manner. Altogether, this is the first report elucidating the underlying mechanisms for modulation of swarming motility by a QseEF-regulated sRNA GlmY, involving expression of cheA, rcsB and flhDC in uropathogenic P. mirabilis.

A Comparison of the Diagnostic Accuracy and Reliability of Subjective Grading and Computer-Aided Assessment of Intranodal Vascularity in Differentiating Metastatic and Reactive Cervical Lymphadenopathy

PURPOSE

Ultrasound is a well-established imaging modality in the assessment of malignant cervical lymphadenopathy. With the use of Doppler ultrasound, intranodal vascularity can be evaluated. However, the major limitation of ultrasound is operator dependency. Therefore, this study aimed to evaluate and compare the diagnostic accuracy and reliability of the subjective grading and computer-aided approach in assessing intranodal vascularity for the differentiation of benign and malignant lymph nodes.

MATERIALS AND METHODS

The present study retrospectively assessed 99 power Doppler ultrasound images of cervical lymph nodes and evaluated the degree of intranodal vascularity using qualitative subjective grading (QSG) and quantitative computer-aided (QCA) methods. The diagnostic accuracy of the two methods in distinguishing metastatic and reactive nodes and their inter- and intra-rater reliability in assessing intranodal vascularity were evaluated and compared.

RESULTS

The results showed that the QCA method was more accurate than the QSG method with a significantly higher sensitivity (67.8 % and 61.9 %, respectively, p < 0.05) and specificity (73.3 % and 57.3 %, respectively, p < 0.05). Using the intranodal vascularity index as determined by the QCA approach, the optimum cut-off to differentiate metastatic and reactive cervical lymph nodes was 32 %. The QCA method showed higher inter- and intra-rater reliability than the QSG method.

CONCLUSION

In the assessment of the degree of intranodal vascularity, the QCA method was more accurate and reliable than the QSG method in distinguishing metastatic and reactive lymph nodes.

Abdominal wall mixed malignant germ cell tumor: a case report and review of literature

Abdominal wall mass is not uncommon in clinic, but it is very rare that germ cell tumors (GCTs) arise in the abdominal wall. The authors review the case of a 34-year-old female with abdominal wall mixed malignant GCT composed of embryonal carcinoma and teratoma and combine the relative literature to explain why GCTs originate from anterior abdominal wall.

Upregulation of endocan by Epstein-Barr virus latent membrane protein 1 and its clinical significance in nasopharyngeal carcinoma

Endocan (or called Esm-1) has been shown to have tumorigenic activities and its expression is associated with poor prognosis in various cancers. Latent membrane protein 1 (LMP1) is an Epstein-Barr virus (EBV)-encoded oncoprotein and has been shown to play an important role in the pathogenesis of EBV-associated nasopharyngeal carcinoma (NPC). To further understand the role of LMP1 in the pathogenesis of NPC, microarray analysis of LMP1-regulated genes in epithelial cells was performed. We found that endocan was one of the major cellular genes upregulated by LMP1. This induction of endocan by LMP1 was confirmed in several epithelial cell lines including an NPC cell line. Upregulation of endocan by LMP1 was found to be mediated through the CTAR1 and CTAR2 domains of LMP1 and through the LMP1-activated NF-κB, MEK-ERK and JNK signaling pathways. To study whether endocan was expressed in NPC and whether endocan expression was associated with LMP1 expression in NPC, the expression of endocan and LMP1 in tumor tissues from 42 NPC patients was evaluated by immunohistochemistry. Expression of endocan was found in 52% of NPC specimens. Significant correlation between LMP1 and endocan expression was observed (p<0.0001). Moreover, NPC patients with endocan expression were found to have a shorter survival than NPC patients without endocan expression (p=0.0104, log-rank test). Univariate and Multivariate analyses revealed that endocan was a potential prognostic factor for NPC. Finally, we demonstrated that endocan could stimulate the migration and invasion ability of endothelial cells and this activity of endocan was dependent on the glycan moiety and the phenylalanine-rich region of endocan. Together, these studies not only identify a new molecular marker that may predict the survival of NPC patients but also provide a new insight to the pathogenesis of NPC.

Semicarbazide-sensitive Amine Oxidase from the Smooth Muscles of Dog Aorta and Trachea: Activation by the MAO-A Inhibitor Clorgyline

Semicarbazide-sensitive amine oxidase (SSAO) has been identified in the dog trachea and aorta smooth muscles. The dog SSAO is blocked by hydrazine inhibitors. SSAOs from several different vascular smooth muscle sources, such as the rat and bovine aorta, and human umbilical artery, as well as the bovine plasma, are insensitive to the MAO-A inhibitor clorgyline; the dog SSAO on the other hand is significantly activated by clorgyline. Two methods, i.e. radioenzymatic and fluoroemetric methods, have been applied to substantiate this clorgyline-induced activation. The activation was detected with respect to the deamination of different substrates, such as benzylamine, β-phenylethylamine and longer carbon chain aliphatic amines, but not with respect to methylamine. The clorgyline effect is reversible, non-competitive and time-independent; it depends on electrostatic and hydrophobic interactions between clorgyline and hydrophobic regions of the dog SSAO enzyme.

The preparedness of Hong Kong medical students towards advance directives and end-of-life issues

OBJECTIVES

To explore the preparedness of medical students towards advance directives and related end-of-life issues, and to examine background factors such as knowledge, attitudes, and experience concerning advance directives and related end-of-life issues.

METHODS

In 2007, 448 medical students in years 3 to 5 were surveyed at the Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong. Their knowledge, attitudes, and experiences of advance directives and related end-of-life issues, and their self-perceived preparedness to discuss these matters with patients were evaluated.

RESULTS

A total of 220 (49%) of the eligible students responded, of whom 79% supported the use of advance directives. Only 65 (30%) students were certain of what advance directives meant and 198 (90%) students felt that their knowledge of advance directives was inadequate. Also, 197 (90%) students felt unprepared about advance directives and end-of-life issues. Factors associated with positive attitude towards advance directives included religion and knowledge. No factors were found to be associated with self-perceived preparedness towards advance directives or end-of-life issues.

CONCLUSIONS

Most of the medical students surveyed demonstrated a positive attitude towards advance directives and recognised the importance of advance directives. However, they felt that they were unprepared and lacking in knowledge and experience of advance directives and end-of-life issues. Wider range and more depth of education is needed to better equip medical students for future practice.

Induction of subcutaneous adipose proliferation by olanzapine in rodents

Weight gain induced by atypical antipsychotics causes a serious health concern in the treatment of schizophrenic patients. In the present study chronic treatment of female Wistar rats with olanzapine caused weight gain, but limited effect on food intake. A dramatic drug-induced morphological change of the subcutaneous adipose tissue was observed, i.e. development of a pinkish coloration with the appearance of a "fish egg"-like texture. Histological examination revealed a massive increase in the proliferation of undifferentiated adipocytes. Such proliferation was detected as early as the third day after olanzapine treatment. The changes progressed in a time- and dose-dependent manner. The proliferation of adipose tissue was detected in rats treated with olanzapine independent of increases in weight gain. Protein profiles of the adipose tissue were also altered by olanzapine. These results suggest that olanzapine-induced weight gain may be not solely due to an effect on behavioural satiety. The potential involvement of adipose neuronal input and proliferation are discussed.

Conversion of food industrial wastes into bioplastics

The usage of plastics in packaging and disposable products, and the generation of plastic waste, have been increasing drastically. Broader usage of biodegradable plastics in packaging and disposable products as a solution to environmental problems would heavily depend on further reduction of costs and the discovery of novel biodegradable plastics with improved properties. In the authors' laboratories, various carbohydrates in the growth media, including sucrose, lactic acid, butyric acid, valeric acid, and various combinations of butyric and valeric acids, were utilized as the carbon (c) sources for the production of bioplastics by Alcaligenes eutrophus. As the first step in pursuit of eventual usage of industrial food wastewater as nutrients for microorganisms to synthesize bioplastics, the authors investigated the usage of malt wastes from a beer brewery plant as the C sources for the production of bioplastics by microorganisms. Specific polymer production yield by A. Latus DSM 1124 increased to 70% polymer/cell (g/g) and 32 g/L cell dry wt, using malt wastes as the C source. The results of these experiments indicated that, with the use of different types of food wastes as the C source, different polyhydroxyalkanoate copolymers could be produced with distinct polymer properties.

Effect of aldehydes derived from oxidative deamination and oxidative stress on β-amyloid aggregation; pathological implications to Alzheimer’s disease

Formaldehyde and methylglyoxal are generated via deamination from methylamine and aminoacetone respectively catalyzed by semicarbazide-sensitive amine oxidase (SSAO). Malondialdehyde (MDA) and 4-hydroxynonenal (HNE) are end products of lipid peroxidation due to oxidative stress. These aldehydes are capable of inducing protein cross-linkage. Elevated levels of aldehydes were found in Alzheimer's disease (AD). These reactive metabolites may potentially play important roles in beta-amyloid (Abeta) aggregation related to the pathology of AD. In the present study thioflavin-T (ThT) fluorometry, an immuno-dot-blot assay and atomic force microscopy (AFM) were employed to reveal the effect of aldehydes on Abeta aggregation in vitro. The target on Abeta for interaction with formaldehyde was identified. The results support the involvement of endogenous aldehydes in amyloid deposition related to AD.

Conversion of industrial food wastes by Alcaligenes latus into polyhydroxyalkanoates

Broader usage of biodegradable plastics in packaging and disposable products as a solution to environmental problems would heavily depend on further reduction of costs and the discovery of novel biodegradable plastics with improved properties. As the first step in our pursuit of eventual usage of industrial food wastewater as nutrients for microorganisms to synthesise environmental-friendly bioplastics, we investigated the usage of soya wastes from a soya milk dairy, and malt wastes from a beer brewery plant as the carbon sources for the production of polyhydroxyalkanoates (PHA) by selected strain of microorganism. Bench experiments showed that Alcaligenes latus DSM 1124 used the nutrients from malt and soya wastes to biosynthesise PHAs. The final dried cell mass and specific polymer production of A. latus DSM 1124 were 32g/L and 70% polymer/cells (g/g), 18.42 g/L and 32.57% polymer/cell (g/g), and 28 g/L and 36% polymer/cells (g/g), from malt waste, soya waste, and from sucrose, respectively. These results suggest that many types of food wastes might be used as the carbon source for the production of PHA.

Involvement of extracellular signal-regulated kinases 1/2 and (phosphoinositide 3-kinase)/Akt signal pathways in acquired resistance against neurotoxin of 6-hydroxydopamine in SH-SY5Y cells following cell-cell interaction with astrocytes

Glial cells interact with neurons and play important roles in the development, differentiation, maintenance and repair of the nervous system. Human neuroblastoma cells (SH-SY5Y) became dramatically resistant to neurotoxin 6-hydroxydopamine (6-OHDA), when co-cultured with mouse astrocytes. In order to further delineate the molecular mechanism involved in the neuroprotection in this selective cell-cell interaction, we assessed the activation of two signal pathways, namely, the MAP kinases (extracellular signal-regulated kinases, ERK1/2) and phosphoinositide 3-kinase (PI3-K)/Akt signal pathways in response to 6-OHDA insult and subsequent neuronal survival. Western blot revealed that 6-OHDA significantly increased the phosphorylation of ERK1/2 and Akt in mono-cultured SH-SY5Y cells. However, the increase in ERK1/2 in SH-SY5Y cells after co-cultured with astrocytes occurred as early as 3 h after 6-OHDA treatment in oppose to the increase after 12 h in monocultures. The phosphorylation of Akt in the co-cultured SH-SY5Y cells was much pronounced 3 h after 6-OHDA treatment compared with that in the mono-cultured cells. The anti-apoptotic protein bcl-2 was also increased in the co-cultured SH-SY5Y cells 3 h after treatment with 6-OHDA. Selective inhibitor of PI3-K/Akt signal pathway blocked the acquired resistance to 6-OHDA in SH-SY5Y cells following interaction with astrocytes. Inhibition of ERK1/2 signal pathway did not affect the cell survival. Our data suggest that PI3-K/Akt signal pathway, but not ERK1/2, is involved the acquired resistance in SH-SY5Y cells following cell-cell interaction with astrocytes against the neurotoxic 6-OHDA insult.

Methanocalculus chunghsingensis sp. nov., isolated from an estuary and a marine fishpond in Taiwan

Three novel halotolerant, hydrogenotrophic methanogens, designated strains K1F9705bT, K1F9705c and O1F9704a, were isolated from an estuary in Eriln Shi, Taiwan, and from a nearby marine water aquaculture fishpond. These isolates were irregular cocci that stained Gram-negative. Strains K1F9705bT and K1F9705c were non-motile, but strain O1F9704a was weakly motile with flagella. They were able to use formate and H2/CO2 to form methane, but they could not catabolize acetate, methanol, trimethylamine or secondary alcohols. Acetate was required for cell growth. Tungsten greatly stimulated the growth of strains K1F9705bT and K1F9705c, but did not affect the growth of strain O1F9704a. Optimal pH and temperature for growth of these three isolates were respectively 7.2 and 37 degrees C. Optimal NaCl concentration for growth was 0.5% for strain O1F9704a and 1.0% for strains K1F9705c and K1F9705bT. Moreover, all strains grew well at up to 8-12% NaCl. Analysis of the 16S rRNA gene revealed that these isolates are members of the genus Methanocalculus, but are distinct from Methanocalculus taiwanensis, Methanocalculus pumilus and Methanocalculus halotolerans, with sequence similarities of 98.4, 98.3 and 98.2%, respectively. In addition, strain K1F9705bT possessed 85, 80, 37, 29 and 10% DNA-DNA relatedness to strain K1F9705c, strain O1F9704a, M. pumilus, M. halotolerans and M. taiwanensis, respectively. Analysis of protein profiles and the Mr of surface (S)-layer glycoprotein subunits showed that these three new isolates are closely related to, but distinct from, known Methanocalculus species. A novel species, Methanocalculus chunghsingensis sp. nov., is proposed for strains K1F9705bT, K1F9705c and O1F9704a. The type strain is K1F9705bT (=OCM 772T=DSM 14646T).

[Environmental investigation in areas where Anopheles anthropophagus distributed in Hubei Province]

OBJECTIVE

To investigate the natural and socio-economical environment in the areas where Anopheles anthropophagus distributed in Hubei Province.

METHODS

5% of the villages in distribution area of An. anthropophagus were randomly selected for the investigation which included vegetation, soil, water, temperature, farming, resting places of the mosquito.

RESULTS

The vegetation of An. anthropophagus area consisted of forest, bush, sod and crops. The area was densely covered with river, ditches and ponds, the water pH being 6.1-7.7. The soil texture was either yellow, yellow brown, grey or black, contained 2.72% organic material. There were one or two seasons of rice plantation in the area and the amount of insecticide used was 0.828 kg/mu in the rice field. The annual average temperature was 16.9 degrees C and the humidity was 76.9%. The breed period of An. anthropophagus was from June to September. There are two peaks of mosquito population in area with two seasons of rice plantation, and one peak in one rice season. The composition of An. anthropophagus resting in households, cowsheds and pigpens was 80.9%, 12.2% and 6.0%, respectively.

CONCLUSION

The distribution of An. anthropophagus was in point, flaky or belt form in low hill, hillock, shallow hilly plain. These areas were full of vegetation and source of water, the principal crop was single cropping of rice, and soil texture is yellow or yellow brown. The major resting place of the mosquito was human dwellings.

[Survey of susceptibility of anopheline vectors to insecticides in a malaria mesoendemic area, Hubei Province]

OBJECTIVE

To determine the susceptibility of Anopheles anthropophagus and Anopheles sinensis to deltamethrin and DDT in an area where different counter-measures had been adopted.

METHODS

The mortality of the vectors was examined by using the standardised WHO test.

RESULTS

The mortality for tentative diagnostic dose in An. anthropophagus to deltamethrin were 83.8%, 83.7% and 84.7%, respectively in the areas where impregnated net had been used for 1 year or 3 years and DDT residual spraying had been carried out for 3 years, suggesting that An. anthropophagus was an initially resistant group. The LT50 were 8.69, 7.48 and 9.87 min, respectively. The mortality for tentative diagnostic dose in An. sinensis to deltamethrin and DDT were 76.5%, 57.0% and 79.0%, respectively in three survey areas, suggesting that An. sinensis was a resistant group. The LT50 were 12.0, 15.4 and 11.2 min, respectively. The mortality for tentative diagnostic dose in An. sinensis to DDT was 95.8% in impregnated net area, suggesting that An. anthropophagus was an initially resistant group. The LC50 was 0.73%. The mortality for tentative diagnostic dose in An. sinensis to DDT was 44%, suggesting that An. sinensis was a highly resistant group. The LC50 was more than 4%.

CONCLUSION

A substantial use of insecticides in the rice paddy field has resulted in resistance of An. sinensis, whereas no apparent resistance of An. anthropophgus has been found.

Role of cell surface components on Cu2+ adsorption by Pseudomonas putida 5-x isolated from electroplating effluent

A gram-negative bacterium Pseudomonas putida 5-x with high Cu2+ accumulating capability was isolated from electroplating effluent in Kwun Tong, Hong Kong. The pretreated cells without superficial layer-capsule, isolated cell envelopes and the separated peptidoglycan layer materials were obtained from fresh P. putida 5-x cells, their Cu2+ adsorption capacities and properties were compared with that of the fresh cells. Pretreatment by 0.1 mol L(-1) HCl enhanced Cu2+ adsorption capacity due to the degradation of cell superficial layer-capsule of P. putida 5-x cells. Isolated cell envelopes possessed five times more Cu2+ adsorption capacity than that of fresh intact cell. The Cu2+ adsorption of separated peptidoglycan layer materials indicated that the peptidoglycan layer only played 10-15% part of the Cu2+ adsorption capacity, and implied other cell surface components such as outer membrane or inner membrane might play an important role in such high Cu2+ binding of the cell envelopes. The adsorption process of fresh cells, pretreated cells and cell envelopes of P. putida 5-x could be described with Freundlich isotherm, while the adsorption of Cu2+ by separated peptidoglycan layer materials was better described with Langmuir isotherm.

Involvement of semicarbazide-sensitive amine oxidase-mediated deamination in atherogenesis in KKAy diabetic mice fed with high cholesterol diet

AIMS/HYPOTHESIS

Semicarbazide-sensitive amine oxidase has been recognised to be a potential risk factor in vascular disorders associated with diabetic complications and to be related to mortality in patients suffering from heart disease. This enzyme, associated with the vascular system, catalyses the deamination of methylamine and aminoacetone, and also acts as an adhesion molecule related to leucocyte trafficking and inflammation. The deaminated products include the toxic aldehydes, formaldehyde and methylglyoxal, respectively, hydrogen peroxide and ammonia.

MATERIALS AND METHODS

In this study, the KKAy mouse, a strain possessing features closely resembling those of Type II (non-insulin-dependent) diabetes mellitus has been used to substantiate the hypothesis. Vascular lesions were induced via chronic feeding of a high cholesterol diet.

RESULTS

Both MDL-72974A, a selective mechanism-based semicarbazide-sensitive amine oxidase inhibitor and aminoguanidine effectively inhibited aorta semicarbazide-sensitive amine oxidase activity, and caused a substantial increase in urinary methylamine, and a decrease in formaldehyde and methylgloxal levels. Inhibition of semicarbazide-sensitive amine oxidase also reduced oxidative stress, as shown by a reduction of malondialdehyde excretion. Both MDL-72974A and aminoguanidine reduced albuminuria, proteinuria and the number of atherosclerotic lesions in animals fed with a cholesterol diet over a period of treatment for 16 weeks.

CONCLUSION/INTERPRETATION

Increased semicarbazide-sensitive amine oxidase-mediated deamination could be involved in the cascade of atherogenesis related to diabetic complications.

Removal and recovery of copper (II) ions by bacterial biosorption

Studies were conducted to investigate the removal and recovery of copper (II) ions from aqueous solutions by Micrococcus sp., which was isolated from a local activated sludge process. The equilibrium of copper biosorption followed the Langmuir isotherm model very well with a maximum biosorption capacity (q(max)) of 36.5 mg of Cu2+/g of dry cell at pH 5.0 and 52.1 mg of Cu2+/g of dry cell at pH 6.0. Cells harvested at exponential growth phase and stationary phase showed similar biosorption characteristics for copper. Copper uptake by cells was negligible at pH 2.0 and then increased rapidly with increasing pH until 6.0. In multimetal systems, Micrococcus sp. exhibited a preferential biosorption order: Cu approximate to Pb > Ni approximate to Zn. There is virtually no interference with copper uptake by Micrococcus sp. from solutions bearing high concentrations of Cl-, SO4(2-), and NO3- (0-500 mg/L). Sulfuric acid (0.05 M) was the most efficient desorption medium, recovering >90% of the initial copper sorbed. The copper capacity of Micrococcus sp. remained unchanged after five successive sorption and desorption cycles. Immobilization of Micrococcus sp. in 2% calcium alginate and 10% polyacrylamide gel beads increased copper uptake by 61%. Biomass of Micrococcus sp. may be applicable to the development of potentially cost-effective biosorbent for removing and recovering copper from effluents.

Production of polyhydroxybutyrate by Bacillus species isolated from municipal activated sludge

Plastic wastes are considered to be severe environmental contaminants causing waste disposal problems. Widespread use of biodegradable plastics is one of the solutions, but it is limited by high production cost. Biologic wastewater treatment generates large quantities of biomass as activated sludge. Only a few reports focus on the potential of utilizing resident Bacillus species from activated sludge in polyhydroxbutyrate (PHB) production as well as the production of PHB from food wastes. They have attractive properties such as short generation time, absence of endotoxins, and secretion of both amylases and proteinases that can well utilize food wastes for nutrients, which can further reduce the cost of production of polyhydroxyalkanoates (PHAs). Two PHA-producing strains, HF-1 and HF-2, were isolated from activated sludge. HF-1 outperformed HF-2 in terms of growth and PHB production in hydrolyzed soy and malt wastes. The isolated bacteria was characterized by DNA sequence alignment. Cell extracts of HF-1 were also compared to Bacillus megaterium cell extracts on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The biopolymers accumulated were analyzed by gas chromatography, nuclear magnetic resonance, and Fourier transform infrared methods.

Prevention of cannabinoid withdrawal syndrome by lithium: involvement of oxytocinergic neuronal activation

Cannabis (i.e., marijuana and cannabinoids) is the most commonly used illicit drug in developed countries, and the lifetime prevalence of marijuana dependence is the highest of all illicit drugs in the United States. To provide clues for finding effective pharmacological treatment for cannabis-dependent patients, we examined the effects and possible mechanism of lithium administration on the cannabinoid withdrawal syndrome in rats. A systemic injection of the mood stabilizer lithium, at serum levels that were clinically relevant, prevented the cannabinoid withdrawal syndrome. The effects of lithium were accompanied by expression of the cellular activation marker Fos proteins within most oxytocin-immunoreactive neurons and a significant increase in oxytocin mRNA expression in the hypothalamic paraventricular and supraoptic nuclei. Lithium also produced a significant elevation of oxytocin levels in the peripheral blood. We suggest that the effects of lithium against the cannabinoid withdrawal syndrome are mediated by oxytocinergic neuronal activation and subsequent release and action of oxytocin within the CNS. In support of our hypothesis, we found that the effects of lithium against the cannabinoid withdrawal syndrome were antagonized by systemic preapplication of an oxytocin antagonist and mimicked by systemic or intracerebroventricular injection of oxytocin. These results demonstrate that oxytocinergic neuronal activation plays a critical role in the action of lithium against the cannabinoid withdrawal syndrome in rats, thus providing a potentially novel strategy for the treatment of cannabis dependence in humans.

Follow-up of plasma semicarbazide-sensitive amine oxidase activity and retinopathy in Type 2 diabetes mellitus

Plasma activity of the enzyme semicarbazide-sensitive amine oxidase (SSAO) is high in diabetes. Production of angiotoxic substances (an aldehyde, hydrogen peroxide, and ammonia) in vessel walls is catalysed by SSAO, suggesting a role for SSAO in the development of complications of diabetes. The objective of the present study was to follow up plasma SSAO activity (measured radiometrically), HbA(1c) (using ion exchange chromatography), and retinopathy (by fundus photography) after 2.8 years, in 34 patients with Type 2 diabetes. We also measured urinary levels of an SSAO substrate, methylamine, by fluorometric high-performance liquid chromatography (HPLC). As at baseline, plasma SSAO activity was now higher in subjects with retinopathy (mean 19.5) than in subjects without retinopathy (mean 16.0), 95% confidence interval (CI) for difference 0.6-6.3 nmol benzylamine ml(-1) plasma h(-1). SSAO activity had not changed significantly since baseline, mean difference -1.65 and 95% CI for difference -3.76 to 0.46 nmol benzylamine ml(-1) plasma h(-1). Mean HbA(1c) level remained higher for patients with retinopathy (now 7.9%) compared to those without retinopathy (6.1%), 95% CI for difference 0.6-3.0%. Comparing baseline and the present study, retinopathy was nonproliferative; level had worsened for five and improved for two patients. Urinary methylamine/creatinine ratio was lower in the group of patients with retinopathy (mean 0.99) than in those without retinopathy (mean 1.78), 95% CI for difference 0.1-1.5 microg mg(-1). The results of the present study are compatible with a role for SSAO in the development of diabetic retinopathy.

Involvement of cerebrovascular semicarbazide-sensitive amine oxidase in the pathogenesis of Alzheimer's disease and vascular dementia

Fibrillary tangles and senile plaques resulting from advanced aggregation of beta-amyloid and other proteins are pathological characteristics of Alzheimer's disease (AD). Cerebral amyloid angiopathy is quite common in AD. In fact, amyloid fibrils fuse to and emanate from the vascular basement membrane. Semicarbazide-sensitive amine oxidase (SSAO), located in outer membranes of vascular smooth muscles and endothelia, catalyzes deamination of methylamine-producing formaldehyde and hydrogen peroxide. SSAO is also involved in lymphocyte adhesion and is up-regulated in response to inflammation. SSAO-mediated generation of formaldehyde can induce protein (i.e. beta-amyloid) cross-linkage, deposition and subsequently plaque formation in the compartment adjacent to the cerebrovessels. Formaldehyde may cause cytotoxicity, which induces inflammation and release of more SSAO, producing a cascade of toxic cycle. Increased SSAO-mediated reaction may be chronically involved in the pathogenesis of vascular dementia and AD.

Inhibition of 6-hydroxydopamine-induced p53 expression and survival of neuroblastoma cells following interaction with astrocytes

The neurotoxin 6-hydroxydopamine has been used to induce selective dopaminergic cell death in animal models of Parkinson's disease. The response of neurons to this toxin has been shown to be greatly influenced by astrocytes. Our laboratory reported previously that human neuroblastoma SH-SY5Y cells became more resistant to the toxicity of 6-hydroxydopamine when co-cultured with mouse astrocytes. This enhanced tolerance required direct and specific adhesion between SH-SY5Y cells and astrocytes. We hypothesized that this interaction led to biochemical changes in SH-SY5Y cells, thereby protecting these cells from toxicity. To study these changes, we again co-cultured SH-SY5Y cells with astrocytes and treated them with 6-hydroxydopamine. An optimized condition of trypsin treatment was employed to separate SH-SY5Y cells from astrocytes quickly. Western blot analysis demonstrated that 6-hydroxydopamine significantly increased p53 protein in monolayer SH-SY5Y cells grown in either regular medium or conditioned medium from astrocytes. This change, however, was not observed in the group co-cultured with astrocytes. Data obtained from the ribonuclease protection assay indicated that similar changes also occurred at the transcriptional level. The enhanced resistance of the co-cultured SH-SY5Y cells to the toxicity of 6-hydroxydopamine is attributed to the ability of astrocytes to prevent the increase of p53 induced by this toxin. This study demonstrates the significance of the interaction between astrocytes and neurons when they are exposed to neurotoxins.

Nutrient release and sediment oxygen demand in a eutrophic land-locked embayment in Hong Kong

Tolo Harbour is a large eutrophic land-locked estuarine embayment in Hong Kong. The rapid urbanization, commercio-industrial activities and lack of legislative control around the Tolo catchment produced large quantities of untreated or partially treated municipal sewage, agricultural wastes and cottage industrial effluents which were discharged into Tolo Harbour via rivers and watercourses. Control measures were implemented to reduce the external nutrient loading into the harbour since the early 1980s. Nutrient data for the period 1982 to 1997 were analyzed for temporal trends. Over the period of observation, the total inorganic nitrogen and total phosphorus both show an increasing trend, despite a decade of efforts in reducing nutrient loading. The release rates of potentially mobile nitrogen (N) and phosphorus (P) from the sediments collected from Tolo Harbour were determined by N and P release experiments under oxic conditions. The experimental results showed that the sediment released significant amount of nutrients, especially orthophosphates and ammonia nitrogen. The maximum release rates were 15.0 and 206.0 mg/m2/day, respectively. Although the external nutrient loading has been reduced, nutrients could gradually be released back into the water column from the contaminated sediments and delay improvement of the water quality.

2-Bromoethylamine as a potent selective suicide inhibitor for semicarbazide-sensitive amine oxidase

Semicarbazide-sensitive amine oxidase (SSAO) catalyzes the deamination of methylamine and aminoacetone to produce toxic aldehydes, i.e. formaldehyde and methylglyoxal, as well as hydrogen peroxide and ammonia. An increase of SSAO activity was detected by different laboratories in patients suffering from vascular disorders, i.e. diabetes and myocardial infarction. The enzyme has been suggested to play a role in vascular endothelial damage and atherogenesis. To date, there are no selective SSAO inhibitors. In the present study, 2-bromoethylamine (2-BrEA) was found to be a highly effective and selective inhibitor of SSAO obtained from different sources. The inhibition was irreversible and time dependent. It was competitive when the enzyme was not preincubated with the inhibitor, but became noncompetitive after incubation of the enzyme with 2-BrEA. The aldehyde trapping agent o-phenylenediamine was capable of preventing 2-BrEA-induced inhibition of SSAO activity. An aldehyde product was detected to be an initial product of 2-BrEA after it was incubated with SSAO. The inhibition, therefore, is mechanism-based. The SSAO inhibitory effects of eight structural analogues of 2-BrEA were assessed. It was concluded that a bromine atom at the beta position is quite important for exerting high potency of SSAO inhibition. The inhibition of SSAO activity by 2-BrEA was also demonstrated in vivo. It increased the urinary excretion of methylamine, an endogenous substrate for SSAO, in mice. 2-BrEA can be employed as a very useful tool in the investigation of SSAO.

The degradation of xenobiotic branched carboxylic acids in anaerobic sediment of the Pearl River in Southern China

Xenobiotic branched carboxylic acids (BCAs) discharged by industries are often persistent in biological wastewater treatment systems and end up in water and sediments. In this study, the degradation of 12 typical BCAs in an anaerobic environment of river sediment was studied in vitro using enrichment shake-flask cultures. The anaerobic consortium taken from the river sediment, comprising BCA-degrading and methane-producing genera, degraded BCAs with tertiary carbons through beta-oxidation, followed by methanogenesis mechanisms. The maximum cell densities in the cultures using BCAs as the sole carbon source ranged between 5.0 and 6.0 x 10(5) cells/ml. The maximum degradation rates were between 5.0 and 8.5 x 10(-3) mmol/h. The consortium could not degrade BCAs with quaternary carbons. The degree of branching at the alpha or beta position along the carbon chain interfered with the beta-oxidation mechanisms. These BCAs would accumulate in the sediment and significantly affect the cycling of organic carbon and nutrients.

The management of isolated thrombocytopenia in Chinese adults: does bone marrow examination have a role at presentation?

We performed a retrospective analysis of bone marrow examination (BME) in the management of Chinese adult patients less than 60 years of age with isolated thrombocytopenia at presentation. Eighty-three patients with a median age of 39 years presenting with isolated thrombocytopenia (median platelet count: 38 x 10(9)/l) had routinely undergone BME as part of the laboratory investigations during the period from January 1996 to December 1999. All 83 patients had bone marrow findings of active marrow suggesting causes due to peripheral destruction. All of these patients responded to steroid or intravenous immunoglobulin (IVIg) therapy at presentation if their platelet counts were significantly low or if they had mucosal bleeding. Eighty-one of the 83 patients, after a median of 20 months follow-up, were finally diagnosed as having idiopathic thrombocytopenic purpura (ITP). The remaining two patients were finally confirmed as cases of systemic lupus erythematosus (SLE). Our results suggest that BME is not helpful in the diagnosis of isolated thrombocytopenia or suspected ITP in adult patients at presentation, provided that a thorough clinical history and physical examination are undertaken and that the blood count and peripheral blood smear show no abnormalities apart from the thrombocytopenia.

Intestinal inflammatory pseudotumour with regional lymph node involvement: identification of a new bacterium as the aetiological agent

Inflammatory pseudotumours are the morphological expression of diverse processes such as reactive/reparative, infective, and neoplastic. This paper reports an example of intestinal inflammatory pseudotumour, with identification of a newly characterized bacterium in the lesion. The patient presented with intestinal obstruction. Laparotomy revealed a tumour in the terminal ileum causing stricture, and multiple enlarged regional lymph nodes. Histologically, the tumour and lymph nodes were composed of plump spindle cells disposed in a vague storiform pattern, and associated with lymphocytes and plasma cells. Immunohistochemical studies showed that most of the spindle cells were histiocytes (CD68 positive), prompting a search for a bacterial aetiology, akin to mycobacterial spindle cell pseudotumour. All histochemical stains for micro-organisms were unrewarding. Ultrastructural studies, however, revealed abundant bacteria within the spindle histiocytes. Polymerase chain reaction, using conserved oligonucleotide primers complementary to the 16S rRNA genes of eubacteria, was employed to amplify 16S rRNA gene fragments directly from the involved lymph node tissue. Phylogenetic analysis of the amplified DNA sequences revealed an organism with 99% sequence conformity to Pseudomonas veronii, a bacterium which has hitherto not been implicated in human infection. The importance of searching for an infective agent in inflammatory pseudotumour in the appropriate setting is re-emphasized.

Design and performance of a fibrous bed bioreactor for odor treatment

Biological processes have become popular for odor treatment. In this study, a novel fibrous bed bioreactor was applied for treatment of odorous gas. The column reactor was packed with spirally wound fibrous sheet material on which a consortium of microorganisms selected from activated sludge was immobilized. The first stage of this work comprised a preliminary study that aimed at investigating the feasibility of the fibrous bed bioreactor for treatment of odorous volatile fatty acids (VFAs). In this stage, the performance of a fibrous bed bioreactor at increasing mass loadings ranging from 9.7 to 104.2 g/(m3.h) was studied. VFA removal efficiencies above 90% were achieved at mass loadings up to 50.3 g/(m3.h). At a mass loading of 104.2 g/(m3.h), removal efficiency was found to be 87.7%. In the second stage of the work, the process was scaled up with design and operational considerations, namely, packing medium, process condition, and configuration selections. A trickling biofilter with synthetic fibrous packing medium was selected. It was operated under countercurrent flow of gas and liquid streams. The effects of inlet concentration and empty bed retention time on bioreactor performance were studied. The bioreactor was effective in treating odorous VFAs at mass loadings up to 32 g/(m3.h), at which VFAs started to accumulate in the recirculation liquid, indicating that the biofilm was unable to degrade all the VFAs introduced. Although VFAs accumulated in the liquid phase, the removal efficiency remained above 99%, implying that the biochemical reaction rate, rather than gas-to-liquid mass transfer rate, was the limiting factor of this process. The bioreactor was stable for long-term operation; no clogging and degeneration of the packing medium was observed during the 4-mo operation.

A novel magnetite-immobilized cell process for heavy metal removal from industrial effluent

The sorption and desorption of copper (II) (Cu[II]) ions from the wastewater by magnetite-immobilized cells of Pseudomonas putida 5-x with acidic pretreatment were studied. Pretreating cells with 0.6 N HCl was found to enhance greatly the adsorption capacity of biomass up to 85.6 mg/g and had no significant effect on the loss of P. putida 5-x cells during biosorbent pretreatment. The biosorption capacity to Cu2+ of magnetite-immobilized cells of P. putida 5-x harvested during various growth phases was also investigated. The experimental results illustrated that the adsorption capacity to Cu2+ of P. putida 5-x cultured in sulfate-limiting medium reached maximum during the late stationary growth phase or early death phase, and reached minimum during the log growth phase. The mechanism of copper sequestering by this type of biomass was studied via transmission electron microscopy. A degradation of the peptidoglycan layer of the cell wall was observed in the acidic pretreatment, but no further degradation appeared after the adsorption-desorption cycle. Cu(II) accumulated mostly on the surface of the cell walls and was effectively desorbed by the acidic treatment during the desorption process.

Effect of food:microorganism ratio in activated sludge foam control

Foaming is a common operational problem in activated sludge processes that often adversely affects the quality of the treated effluent. Overgrowth of the filamentous Nocardia spp. in the microbial ecosystem was previously identified as the cause of foaming. In the present study, the specific growth rate of Nocardia amarae was found to be much higher than that of nonfilamentous bacteria under food:microorganism (F:M) ratios lower than 0.5 mg of biological oxygen demand (BOD)/(mg of mixed liquor suspended solids [MLSS].d). This indicated that filamentous overgrowth may occur in normal activated sludge processes that are continually operated under the usual F:M range of 0.2-0.6 mg of BOD/(mg of MLSS.d). A novel two-component feast-fast operation (FFO) that capitalized on the sensitivity of filamentous bacteria to F:M ratio was designed to prevent and control foaming problems. The F:M ratio in the "feasting" aeration unit was 0.8 mg of BOD/(mg of MLSS.d) whereas that in the "fasting" aeration unit was 0.2 mg of BOD/(mg of MLSS.d). The FFO resulted in an overall process F:M ratio that still remained within the normal range, while avoiding prolonged exposure of the activated sludge ecosystem to an F:M ratio below 0.5 mg of BOD/(mg of MLSS.d). The FFO suppressed the overgrowth of filamentous bacteria without adversely affecting the organic treatment efficiency of the modified process.

Optimal production of polyhydroxyalkanoates in activated sludge biomass

Polyhydroxyalkanoates (PHAs) have been recognized as good candidates for biodegradable plastics, but their high price compared with conventional plastics has limited their use. In this study, activated sludge microorganisms from a conventional wastewater treatment process were induced, by controlling the carbon:nitrogen (C:N) ratio in the reactor liquor, to accumulate PHAs. In addition, an intermittent nitrogen feeding program was established to optimize the volumetric PHA productivity in a wastewater treatment process. The optimal overall polymer production yield of 0.111 g of polymer/g of carbonaceous substrate consumed was achieved under a C:N ratio of 96:1 by feeding nitrogen in the reactor liquor once every four cycles. At the same time, the amount of excess sludge generated from the wastewater treatment process was reduced by 22.9%.

Effect of C:N molar ratio on monomer composition of polyhydroxyalkanoates produced by Pseudomonas mendocina 0806 and Pseudomonas pseudoalkaligenus YS1

Polyhydroxyalkanoates (PHAs) are biodegradable polymers produced by bacteria. In this study, the effect of C:N molar ratio on the monomer composition of PHAs was investigated, including medium chain length PHA produced by Pseudomonas mendocina 0806 and PHA blends consisting of monomers of 3-hydroxybutyrate and medium chain length hydroxyalkanoate produced by Pseudomonas pseudoalkaligenus YS1. It was observed that there were some fixed ranges of C:N molar ratio that affect the monomer composition of PHA independently of the substrate. For strain 0806, the ranges were C:N < 20, 20 < C:N < 200, and C:N > 200. The monomer composition was constant among these ranges when using glucose and octanoate as the sole substrate. For strain YS1, the ranges were C:N < 20, 20 < C:N < 45, and C:N > 45. These results are useful for controlling monomer composition in PHA production.

Effects of trace levels of copper, chromium, and zinc ions on the performance of activated sludge

The effects of copper, chromium, and zinc ions, at trace levels, on the performance of a simulated activated sludge process were investigated. The results of batch adsorption experiments showed that the adsorption of copper, chromium, and zinc ions followed both the Langmuir and Freundlich isotherms. The presence of trace levels of these three metals not only reduced the adsorption rate of organic matters but also the chemical oxygen demand adsorption capacity (CAC) of the activated sludge. Metal ions competed with the organic substrate for adsorption binding sites on the surfaces of activated sludge bioflocs and reduced the CAC. Studies performed in a sequential batch reactor (SBR) showed that the presence of trace levels of heavy metal ions in wastewater affected the SBR performance to different extents depending on the hydraulic retention time (HRT). When the reactors were operated at short HRTs of 2.5 d or less, the presence of trace levels of heavy metal ions reduced substantially the CAC of activated sludge, which, in turn, affected significantly the performance of the SBR. However, under longer HRTs (e.g., 5 d), the heavy metal ions in the wastewater reduced the CAC but had no significant effect on the chemical oxygen demand removal efficiency.

Hyperproduction of polyesters consisting of medium-chain-length hydroxyalkanoate monomers by strain Pseudomonas stutzeri 1317

Pseudomonas stutzeri strain 1317 was found to grow on various fatty acids, alcohols, diols, as well as glucose and gluconate for the synthesis of polyhydroxyalkanoates (PHA) with various monomer units. The PHA monomer structures were dependent on the type of fatty acids and alcohols, as well as the diols in the culture media. Only even number monomers, such as 3-hydroxyhexanoate (HHx), 3-hydroxyoctanoate (HO) and 3-hydroxydecanoate (HD), were accumulated when even numbered fatty acids, alcohols, glucose and gluconate, as well as diol were used as carbon sources. Odd numbered fatty acids and odd numbered alcohols led to the formation of odd numbered monomers, such as 3-hydroxyvalerate (HV), 3-hydroxyheptanoate (HHp), 3-hydroxynonanoate (HN) and 3-hydroxyundecanoate (HU). The strain tolerated up to 1.5% of ethanol and made 8.3% of PHA when growth was conducted in 1.2% of ethanol. PHA formed up to 77% of cell dry weight when the strain was grown in tridecanoate. PHA synthesis was highly dependent on the nitrogen source. A depletion in nitrogen supply immediately resulted in PHA accumulation in cells grown in the glucose mineral medium.

Alloimmunization in Chinese with warm autoimmune haemolytic anaemia - incidence and characteristics

We perform a retrospective study to determine the incidence and characteristics of alloimmunization in Chinese patients with warm autoimmune haemolytic anaemia. Among 67 patients studied, clinically significant alloantibodies were found in only eight patients, giving a rate of alloimmunization of 11.3%. The latter contrasts with the much higher rate reported in the Western population. This probably reflects the genetic homogeneity in Chinese with respect to the red cell phenotype. The alloimmunization rate, however, is still significant and therefore comprehensive pretransfusion testing is required for Chinese patients with warm autoantibodies so as to safeguard patient's safety.

Potential cytotoxic effect of chronic administration of creatine, a nutrition supplement to augment athletic performance

Creatine is alleged to be an ergogenic aid to enhance sports performance and recently became a popular sports nutrition supplement. Although short-term supplementation of creatine has not been associated with major health risks, the safety of prolonged use has caused some concern. The present study demonstrates that creatine is metabolized to methylamine, which is further converted to formaldehyde by semicarbazide-sensitive amine oxidase (SSAO). Formaldehyde is well known to cross-link proteins and DNAs, and known to be a major environmental risk factor. SSAO-mediated production of toxic aldehydes has been recently proposed to be related to pathological conditions such as vascular damage, diabetic complications, nephropathy, etc. Chronic administration of a large quantity of creatine can increase the production of formaldehyde, which may potentially cause serious unwanted side-effects.

Effect of the Hypericum perforatum extract on serotonin turnover in the mouse brain

St. John's Wort, a traditional herbal medicine obtained from the extract of Hypericum perforatum, has been used in the treatment of mild depression. Its mechanism of action remains to be established. The present study confirmed that Hypericum extract exhibited very weak inhibitory activities towards MAO. Mouse brain MAO activities was unchanged following either acute or chronic treatment with Hypericum extract. 5-HIAA levels were found to be significantly increased in the cerebral cortex, hypothalamus, hippocampus and caudate 3 h after treatment with the Hypericum extract at a dose as low as 10 mg/Kg. An increase of 5-HT levels was also observed in hypothalamus and hippocampus. The increase of brain 5-HIAA was not further enhanced following chronic administration of the herb. The Hypericum extract significantly reduced the plasma tryptophan levels, the precursor of 5-HT. The action of Hypericum extract is consistent with the notion that serotonergic system is involved. The effect of Hypericum extract on the brain 5-HIAA and 5-FIT levels appeared to be quite different from the effect of classical 5-HT re-uptake blockers.

Microbial production of polyhydroxyalkanoates by bacteria isolated from oil wastes

A Gram-positive coccus-shaped bacterium capable of synthesizing higher relative molecular weight (M(r)) poly-hydroxybutyrate (PHB) was isolated from sesame oil and identified as Staphylococcus epidermidis (by Microbial ID, Inc., Newark, NJ). The experiment was conducted by shake flask fermentation culture using media containing fructose. Cell growth up to a dry mass of 2.5 g/L and PHB accumulation up to 15.02% of cell dry wt was observed. Apart from using single carbohydrate as a sole carbon source, various industrial food wastes including sesame oil, ice cream, malt, and soya wastes were investigated as nutrients for S. epidermidis to reduce the cost of the carbon source. As a result, we found that by using malt wastes as nutrient for cell growth, PHB accumulation of S. epidermidis was much better than using other wastes as nutrient source. The final dried cell mass and PHB production using malt wastes were 1.76 g/L and 6.93% polymer/cells (grams/gram), and 3.5 g/L and 3.31% polymer/cells (grams/gram) in shake flask culture and in fermentor culture, respectively. The bacterial polymer was characterized by 1H-nuclear magnetic resonance (NMR), 13C-NMR, Fourier transform infrared, and differential scanning calorimetry. The results show that with different industrial food wastes as carbon and energy sources, the same biopolymer (PHB) was obtained. However, the use of sesame oil as the carbon source resulted in the accumulation of PHB with a higher melting point than that produced from other food wastes as carbon sources by this organism under similar experimental conditions.

Construction of recombinant Escherichia coli strains for polyhydroxybutyrate production using soy waste as nutrient

Construction and comparison of recombinant Escherichia coli strains harboring the polyhydroxybutyrate (PHB) operon from Ralstonia eutropha using vectors possessing different promotors, as well as the production of PHB from soy waste by the recombinant strain, are reported. The lac promotor was the most efficient on expression of the phb operon among the three promotors studied: i.e., lac promotor, T7 promotor and the normal sigma 70 promotor. The pKS/PHB was the most efficient plasmid for phb operon expression among the three plasmids used: i.e., pKS-, pAED4, and pJM9131. It was observed that isopropyl-beta-D-thiogalactopyranoside was not required for the induction of the expression of phb operon. The cell dry wt and polyhydroxyalkanoate content by E. coli XL-1 Blue (pKS/PHB) were 3.025 g/L and 27.83%, respectively.

Sub-lethal effects of heavy metals on activated sludge microorganisms

The effects of heavy metals, at sub-lethal concentrations, on activated sludge microbial ecosystem were investigated. Adsorption capacity and rate of copper, chromium, lead and zinc on microbial flocs were much faster than that of organic matters. Metals affected not only the adsorption rate of organic matters but also the COD adsorption capacity of the activated sludge. Effects of heavy metals, on wastewater treatment performance of a sequencing batch reactor were also studied. Metal-laden wastewater at sub-lethal levels affected the performance to different extents, depending on the hydraulic retention time. Metal ions acted as a strong competitor against the organic compounds for active sites on the bioflocs instead of acting as a toxic microbial inhibitor, thus hampering organic adsorption and affecting the COD removal efficiency under shorter HRTs.

Inversion of selectivity of N-substituted propargylamine monoamine oxidase inhibitors following structural modifications to quaternary salts

A number of N-substituted-propargylamines are well known mechanism-based MAO inhibitors. Clorgyline and deprenyl in fact represent archetypal MAO-A and MAO-B inhibitors respectively. In the present study several ring-substituted deprenyl structural analogues were synthesized and alterations of selectivity and potency towards MAO-A and MAO-B activities were found. When deprenyl and its structural analogues were further modified to their corresponding quaternary ammonium salts. i.e. by attaching either an extra propargyl or a methyl group to the nitrogen atom, the potency of inhibition of MAO-B activity was drastically reduced and inhibition of MAO-A activity substantially increased. Such a complete inversion of selectivity may be related to a hydrophilic and electrophilic region seemingly present only in the MAO-A but not in the MAO-B molecule. The results also suggest that at least three sites are required for the selectivity and mechanism-based action of an inhibitor towards MAO.

Differential effects of staurosporine and retinoic acid on the vulnerability of the SH-SY5Y neuroblastoma cells: involvement of bcl-2 and p53 proteins

Human catecholaminergic neuroblastoma cells (SH-SY5Y) have been widely used in different neurochemical investigations. Quite often these cells are induced to differentiation by various agents, such as staurosporine and retinoic acid. Interestingly, even though both staurosporine and retinoic acid induce similar morphological differentiation in SH-SY5Y cells, we found that these two groups of differentiated cells exhibited opposite vulnerability to harmful chemicals and physical insults. In the present study, cisplatin, 5-fluorouracil (5-FU), N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), 6-hydroxydopamine (6-OHDA), and gamma-radiation were used to assess the tolerance of the differentiated cells. Cell viability was determined by 3-(4,5-dimethylthiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Staurosporine-treated SH-SY5Y cells were more sensitive to these toxic insults than the untreated controls. In contrast, retinoic acid-treated cells became more resistant to the same treatments. The expression of the proteins of the protooncogene Bcl-2 and the tumor suppressor gene p53 following staurosporine or retinoic acid treatment was assessed by Western blot and immunocytochemistry. Retinoic acid increased Bcl-2 and decreased p53 levels, whereas staurosporine decreased Bcl-2 and increased p53 levels. The opposite alteration of Bcl-2 (anti-apoptotic) and p53 (apoptotic) contents in SH-SY5Y cells with retinoic acid and staurosporine are attributed to the changes in cell vulnerability. These observations also indicate that caution should be taken when chemically induced differentiated neuroblastoma cells are to be used as an in vitro model for studying neuronal survival.

Translocation (12;17)(q13;q23) in de novo acute myeloid leukemia with trilineage myelodysplasia

12q13 abnormalities have been reported to be associated with a variety of benign and malignant solid tumors. Recently, they have been shown to be a nonrandom karyotypic change in acute myeloid leukemia. We report a case of de novo acute myeloid leukemia with trilineage myelodysplasia showing t(12;17)(q13;q23) as the sole chromosomal abnormality. A review of the literature indicates that 12q13 translocation in acute myeloid leukemia is often associated with concomitant dysmyelopoietic changes. There is also evidence to suggest that 12q13 translocation occurs more frequently in acute myeloid leukemia with a prior history of mutagenic exposure or karyotypic indicators of secondary leukemia.

Simultaneous determination of formaldehyde and methylglyoxal in urine: involvement of semicarbazide-sensitive amine oxidase-mediated deamination in diabetic complications

The deamination of methylamine and aminoacetone by semicarbazide-sensitive amine oxidase (SSAO) produces formaldehyde and methylglyoxal, respectively, which have been presumed to be involved in diabetic complications. A high-performance liquid chromatography procedure using 2,4-dinitrophenylhydrazine (DNPH) as a derivatizing agent is developed to determine endogenous formaldehyde, methylglyoxal, malondialdehyde, and acetaldehyde. The devised DNPH method is sensitive enough to analyze aldehyde levels in urine. An increase in the excretion of formaldehyde, methylglyoxal, and malondialdehyde is confirmed in streptozotocin-induced diabetic rats. Following the chronic administration of methylamine, the urinary levels of both formaldehyde and malondialdehyde (a product from lipid peroxidation) are found to be substantially increased. A potent selective SSAO inhibitor, (E)-2-(4-fluorophenethyl)-3-fluoroallylamine hydrochloride (MDL-72974A), reduced the formation of formaldehyde, methylglyoxal, and malondialdehyde. The increase of the cytotoxic aldehyde levels as a result of increased SSAO-mediated deamination may occur in some pathological conditions.

Mantle cell lymphoma in leukemic phase: characterization of its broad cytologic spectrum with emphasis on the importance of distinction from other chronic lymphoproliferative disorders

BACKGROUND

Mantle cell lymphoma is a mature, virgin B-cell neoplasm characterized immunologically by a panB+, CD5+, CD23-, cyclin D1+ phenotype and genetically by t(11;14)(q13;q32) with overexpression of the cyclin D1 (bcl-1) gene. It usually presents as advanced stage disease, involving lymph nodes, spleen, bone marrow, and extranodal sites, particularly the gastrointestinal tract. However, frank leukemic presentation with high white cell counts is uncommon and can be difficult to distinguish from other chronic lymphoproliferative disorders. The aim of this study was to characterize the morphologic spectrum of leukemic mantle cell lymphoma.

METHODS

During the period July 1994 through October 1998, 14 patients with mantle cell lymphoma in leukemic phase were diagnosed at the Department of Pathology, Queen Elizabeth Hospital, Hong Kong. The diagnosis of mantle cell lymphoma was based on histologic and immunocytochemical findings and was confirmed by cyclin D1 immunoreactivity in all cases. The clinical records and laboratory results were reviewed. Peripheral blood smears, bone marrow, and other tissue biopsies were examined, with particular attention to the cytologic features of the leukemic mantle cells.

RESULTS

Mantle cell lymphoma in leukemic phase showed a very aggressive clinical course. Eight patients died at a mean of 13 months, and only 1 patient was disease free. Morphologically, the leukemic mantle cells exhibited a broad morphologic spectrum, with several cytologic patterns identified: 1) mixed small and medium-sized cells, 2) predominantly medium-sized cells, 3) predominantly large cells, and 4) giant cells. Despite variations in the size and nuclear shape, the leukemic mantle cells could usually be recognized by the nuclear irregularity and clefting, moderately dense but evenly distributed chromatin, small nucleoli, and scant cytoplasm.

CONCLUSIONS

Recognition of the characteristic cytologic features of leukemic mantle cells can help to distinguish them from other chronic lymphoproliferative disorders. In contrast to the latter, the clinical course is aggressive and response to conventional chemotherapy is poor.

MK-801-induced expression of Fos protein family members in the rat retrosplenial granular cortex

The N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 has been shown to induce an acute Fos and Fos-related antigen (Fra) expression in the rat retrosplenial granular cortex (RSG), but the exact composition of the Fos protein family and their individual dynamic alterations are unknown. We examined this issue using immunocytochemistry and Western blot analysis with two antibodies that recognize, respectively, Fos and all the identified members of Fos protein family. Immunocytochemistry detected a rapid and transient expression of Fos proteins in some RSG neurons and a delayed and prolonged expression of Fra proteins in most RSG neurons following a single systemic MK-801 injection (1 mg/kg). Multiple MK-801 injections (i.e., ten consecutive injections once every other day; 1 mg/kg) produced a moderate Fra expression but failed to induce detectable Fos expression. Western blot analysis further showed a transient expression of 72-kDa Fos proteins following a single MK-801 injection and a prolonged expression of 46- and 43-kDa Fra proteins after either a single or multiple MK-801 administration. The delayed onset and prolonged expression of these Fra proteins suggest that they may be DeltaFosB. The possible relevance of these results to clinical psychotomimetic effects of the NMDA receptor antagonists phencyclidine and ketamine is discussed.

A man with natural killer cell lymphoma showing 46,XX and deletion 6q

Specific chromosomal abnormalities have been shown to be associated with certain types of leukemia and lymphoma. We and others have recently demonstrated del(6)(q21q25) as being strongly associated with natural killer cell lymphoma/leukemia. In this report, we describe a case of natural killer cell lymphoma with a clonal chromosomal abnormality of 46,X,-Y,+X,t(2;9)(q31;p24), del(4)(q21q25),del(6)(q21q23), and propose that the region 6q23 is probably an important site of genetic alteration in this group of tumors.

Assessment of the deamination of aminoacetone, an endogenous substrate for semicarbazide-sensitive amine oxidase

Methylglyoxal, a toxic aldehyde, has been reported to be increased in diabetes and has been claimed to be related to diabetic complications. Aminoacetone, an intermediate in the metabolism of threonine and glycine, has been proposed to be an endogenous substrate for semicarbazide-sensitive amine oxidase (SSAO). Methylglyoxal is the product. An HPLC procedure for the determination of SSAO activity toward aminoacetone in vitro is described. It was observed in previous assays that methylglyoxal formed via deamination of aminoacetone was quite unstable and led to erroneous results. o-Phenylenediamine (o-PD) was therefore employed for derivatization of methylglyoxal. o-PD does not affect SSAO activity and can be included in the enzyme reaction mixture for continuous trapping of methylglyoxal. This can avoid the loss of methylglyoxal during incubation. Deamination of aminoacetone by human umbilical artery SSAO was confirmed with this improved assay. The values of Km and Vmax, are 125.9 +/- 20.5 microM and 332.2 +/- 11.7 nmol/h/mg protein, respectively. Deamination of aminoacetone was nearly completely inhibited by 1 mM semicarbazide and 1 microM MDL-72974A, a potent selective SSAO inhibitor, whereas MAO inhibitors clorgyline (1 mM) and deprenyl (1 mM) had no inhibitory effect.