Comparison of methods for reducing the effects of scattering in spectrophotometry

Light scattering provides a problem in optical spectroscopy as the relationship between attenuation and absorption in the presence of scattering is nonlinear. Three simple methods of reducing the effects of scattering and hence returning to an approximately linear relationship are considered in this paper, namely, extracting light that has maintained its original polarization state through subtraction of orthogonal polarization states, use of an added absorber, and spatial filtering. These can all be applied relatively easily to conventional spectrophotometers. However, there is an inevitable trade-off between the accuracy of the measurement and the signal-to-noise ratio as scattered light is rejected from the detector. It is demonstrated that polarization subtraction is the most efficient technique at selecting weakly scattered photons from a scattered light background as it enables the relationship between attenuation and absorption coefficient to become more linear while maintaining a higher number of detected photons. In practical use, the drawback of polarization subtraction over added absorber and spatial filtering methods is that a large dc background light level is maintained, which contributes to a higher shot noise. This means that when the scattering coefficient is high (micros > or = 7 mm(-1)) the added absorber method offers better performance for shot noise limited detection.

Catalytic oxidation of benzene using DBD corona discharges

Plasma oxidation of benzene (C(6)H(6)) in oxygen and nitrogen was investigated using a dielectric barrier discharge (DBD) reactor with or without MnO2 or TiO2 at atmospheric pressure and without external heating except plasma heating. An alternative current power supply was used to generate corona discharges for the plasma oxidation. The energy density was controlled under 200 J/L to keep an increase in gas temperature less than 167 K. C(6)H(6) was oxidized to carbon monoxide (CO) and dioxide (CO(2)). Typically, the energy efficiency at an energy density of 92J/L was about 0.052, 0.039, and 0.024 mol/kWh with MnO2, TiO2, and without MnO2 and TiO2, respectively. Benzene oxidation mechanism was mentioned. A comparison on energy efficiency as a function of initial concentration of hydrocarbons, inorganic sulphur compounds, and chloro (fluoro and bromo) carbons was given.

A novel mitochondrial DNA missense mutation at G3421A in a family with maternally inherited diabetes and deafness

OBJECTIVE

Mutations in mtDNA are thought to be responsible for the pathogenesis of maternally inherited diabetes. Here, we report a family with maternally inherited diabetes and deafness whose members did not harbour the mtDNA A3243G mutation, the most frequent point mutation in mitochondrial diabetic patients. This study aimed to investigate a possible other mtDNA mutation and its prevalence in type 2 diabetic patients.

METHODS

Height, body weight, waistline, and hip circumference were measured and serum biochemical marks determined in all members of the family. In addition, a 75 g oral glucose tolerance test and electric listening test were conducted in these members. Genomic DNA was prepared from peripheral leukocytes. Direct sequencing of PCR products was used to detect the mtDNA mutation in this family. The prevalence of mtDNA G3421A nucleotide substitutions was investigated by restriction fragment length polymorphism analysis in 1350 unrelated type 2 diabetic patients recruited by random cluster sampling from the central city area of Shanghai, China.

RESULTS

(1) A new missense homoplasmic mutation of mtDNA G3421A was found in a maternally inherited diabetic family and existed neither in 1350 unrelated type 2 diabetic patients nor in 50 non-diabetic individuals. (2) The mode of mutation and diabetes transmission was typical maternal inheritance in this family. (3) All diabetic family members were found to have an onset at 35-42 years of age, accompanied by deafness of varying degrees.

CONCLUSION

mtDNA G3421A (Val39Ile) found in a family with maternally inherited diabetes and deafness is a novel missense mutation. Whether this is a diabetogenic mutation and its effect on mitochondrial function needs to be further studied.

Lipid trafficking between the endoplasmic reticulum and the chloroplast

The photosynthetic (thylakoid) membrane of plants is one of the most extensive biological cell membrane systems found in Nature. It harbours the photosynthetic apparatus, which is essential to life on Earth as carbon dioxide is fixed and atmospheric oxygen released by photosynthesis. Lipid biosynthetic enzymes of different subcellular compartments participate in the biogenesis of the thylakoid membrane system. This process requires the extensive exchange of lipid precursors between the chloroplast and the ER (endoplasmic reticulum). The underlying lipid trafficking phenomena are not yet understood at the mechanistic level, but genetic mutants of the model plant Arabidopsis thaliana with disruptions in lipid trafficking between the ER and the chloroplast have recently become available. Their study has led to the identification of components of the lipid transfer machinery at the inner chloroplast envelope.

PDGFR-β expression in small cell lung cancer patients

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Background: Small cell lung cancer (SCLC) carries an extremely poor prognosis and treatment options for this disease remain poor. PDGF and PDGFR-β are expressed and have been found to have prognostic value in several human cancers. Data in non-small cell cancer cell lines have suggested that PDGFR is a therapeutic target for drug development. In the current study PDGFR-β expression and prognostic value in SCLC was investigated. Methods: Paraffin embedded tissue blocks from 53 patients with limited and extensive stage SCLC were obtained for immunohistochemical staining. Tumors from each patient were sampled three times and stained with PDGFR-β specific antibody. Patients were divided into low and high staining groups based on intensity. Results: There was high intensity PDGFR-β staining in 20 patients with SCLC. Another 29 expressed low intensity PDGFR- β staining, with only 4 patients showing no PDGFR- β staining. There was no statistically significant difference in five year overall survival between patients with low levels of PDGFR-β staining versus those with high level staining SCLC tumors (P = 0.538). Conclusions: Though expression of PDGFR-β may not be a predictor of prognosis, due to its high expression in SCLC it may represent an important target for improved tumor control, however, further studies are required to confirm this.

No significant financial relationships to disclose.

Plasminogen Activator Inhibitor-1 Promoter Polymorphism is Not Associated With the Aggressiveness of Disease in Prostate Cancer

AIMS

PAI-1 (plasminogen activator inhibitors-1) regulates plasminogen activation, and is related to tumour development. This study aims to test whether the promoter polymorphism in the PAI-1 gene is related to the aggressiveness of disease in prostate cancer.

MATERIALS AND METHODS

In the present study, Taqman SNP genotyping assay was used to detect PAI-1 4G/5G polymorphism in DNA from paraffin-embedded tissues of 98 Caucasian patients with prostate cancer.

RESULTS

The distribution of the genotypes is in Hardy-Weinberg equilibrium. The genotype had no statistically significant relationship with other prognostic factors. Similar risks for recurrence were seen in individuals with the 4G/4G and 4G/5G genotypes compared to those with 5G/5G genotype (odds ratio [OR] 2.65, 95% CI: 0.41-16.94, P = 0.30; OR = 2.19, 95% CI: 0.38-12.49, P = 0.38).

CONCLUSION

We concluded that PAI-1 promoter polymorphism is not associated with the aggressiveness of disease in prostate cancer.

BMP2 gene therapy on the repair of bone defects of aged rats

Age-related decline in the number of mesenchymal stem cells (MSCs) and their reduced capability to differentiate osteogenically, along with diminished availability of growth factors, may be major factors accounting for reduced bone formation in the aging mammalian body. In the first part of the study, we compared the number of MSCs in bone marrow (BM) and the content of bone morphogenetic protein 2 (BMP2) in cortical bone tissue in juvenile, adult, and aged (1, 9, and 24 months, respectively) male rats. To assay the influence of aging on osteogenic differentiation ability, MSCs from the three age groups were transduced with the BMP2 gene. Following gene transduction, the production of BMP2 in culture media, expression of osteogenic proteins (e.g., alkaline phosphatase, type Ialpha1 collagen, osteopontin, and bone sialoprotein), as well as ectopic bone formation in athymic mice were compared. Results showed that the number of MSCs in BM as well as the content of BMP2 in cortical bone tissue decreased with age, but no significant differences between the three age groups were found with regard to production of BMP2 or capability of BMP2 gene-modified MSCs to differentiate osteogenically. The second part of the study applied BMP2 gene-modified autologous MSCs/beta-tricalcium phosphate for repair of bone defects in aged rats with positive results. Our data indicate that the osteogenic potential of MSCs of aged rats can be restored following BMP2 gene transduction and that this technique may be a useful approach in the future planning of gene therapy for age-related osteoporotic fractures.

Differential influence of chemokine receptors CCR2 and CXCR3 in development of atherosclerosis in vivo

BACKGROUND

Recruitment of mononuclear leukocytes within atherosclerotic lesions is a critical step in atherogenesis. Mice lacking the chemokine receptor CCR2, highly expressed on macrophages but also on T lymphocytes, show a striking reduction of atherosclerotic lesion formation. The chemokine receptor CXCR3 is a marker of activated T helper type 1 lymphocytes, the principal T lymphocyte type detected within atheroma. We investigated whether the deletion of both of these 2 important receptors expressed on the principal inflammatory cells present in atheroma would further affect atherogenesis in vivo.

METHODS AND RESULTS

We crossed ApoE(-/-) mice with either CCR2(-/-) or CXCR3- mice and crossed ApoE(-/-) CCR2(-/-) mice with the ApoE(-/-) CXCR3- mice to generate a triple knockout strain. Analysis of atherosclerosis development after 10 weeks of high-cholesterol diet revealed differential effects on early atherosclerotic lesions in the abdominal aorta and on advanced lesions in aortic roots. ApoE(-/-) CXCR3- mice, but not the triple knockout mice, displayed significantly reduced atherosclerotic lesion development within abdominal aortas compared with ApoE(-/-) CCR2(-/-) and ApoE(-/-) mice. This reduction of lesion formation correlated with an upregulation of antiinflammatory molecules such as interleukin-10, interleukin-18BP, and endothelial nitric oxide synthase and with an increased number of regulatory T lymphocytes within atherosclerotic lesions. In contrast, lesion size development within the aortic roots was more enhanced in ApoE(-/-) and ApoE(-/-) CXCR3- mice compared with ApoE(-/-) CCR2(-/-) and triple knockout mice.

CONCLUSIONS

Blocking chemokine signaling in vivo through deletion of the chemokine receptors CCR2 and CXCR3 has differential effects during atherogenesis. In addition, our results point to an important role of regulatory T lymphocytes during early atherogenesis.

Measuring the cone contribution to the ERG b-wave to assess function and predict anatomical rescue in RCS rats

Subretinal injections of human retinal pigment epithelial (RPE) cells early in the course of retinal degeneration in Royal College of Surgeons (RCS) rats can rescue photoreceptors. Fourteen injected animals were studied using a double flash electroretinogram (ERG): 10 were examined longitudinally and four terminally with immunohistochemistry. The proportion of cone contribution to the ERG b-wave rather than the absolute size of isolated cone response proved to be a reliable indicator of function over time and a predictor of the proportion of cones identified anatomically in the area of optimal photoreceptor rescue.

Inducers of oxidative stress block ciliary neurotrophic factor activation of Jak/STAT signaling in neurons

Generation of reactive oxygen species (ROS) with the accumulation of oxidative damage has been implicated in neurodegenerative disease and in the degradation of nervous system function with age. Here we report that ROS inhibit the activity of ciliary neurotrophic factor (CNTF) in nerve cells. Treatment with hydrogen peroxide (H(2)O(2)) as a generator of ROS inhibited CNTF-mediated Jak/STAT signaling in all cultured nerve cells tested, including chick ciliary ganglion neurons, chick neural retina, HMN-1 motor neuron hybrid cells, and SH-SY5Y and BE(2)-C human neuroblastoma cells. H(2)O(2) treatment of non-neuronal cells, chick skeletal muscle and HepG2 hepatoma cells, did not inhibit Jak/STAT signaling. The H(2)O(2) block of CNTF activity was seen at concentrations as low as 0.1 mm and within 15 min, and was reversible upon removal of H(2)O(2) from the medium. Also, two other mediators of oxidative stress, nitric oxide and rotenone, inhibited CNTF signaling. Treatment of neurons with H(2)O(2) and rotenone also inhibited interferon-gamma-mediated activation of Jak/STAT1. Depleting the intracellular stores of reduced glutathione by treatment of BE(2)-C cells with nitrofurantoin inhibited CNTF activity, whereas addition of reduced glutathione protected cells from the effects of H(2)O(2). These results suggest that disruption of neurotrophic factor signaling by mediators of oxidative stress may contribute to the neuronal damage observed in neurodegenerative diseases and significantly affect the utility of CNTF-like factors as therapeutic agents in preventing nerve cell death.