A Multi-Threshold Sampling Method for TOF PET Signal Processing

As an approach to realizing all-digital data acquisition for positron emission tomography (PET), we have previously proposed and studied a multi-threshold sampling method to generate samples of a PET event waveform with respect to a few user-defined amplitudes. In this sampling scheme, one can extract both the energy and timing information for an event. In this paper, we report our prototype implementation of this sampling method and the performance results obtained with this prototype. The prototype consists of two multi-threshold discriminator boards and a time-to-digital converter (TDC) board. Each of the multi-threshold discriminator boards takes one input and provides up to 8 threshold levels, which can be defined by users, for sampling the input signal. The TDC board employs the CERN HPTDC chip that determines the digitized times of the leading and falling edges of the discriminator output pulses. We connect our prototype electronics to the outputs of two Hamamatsu R9800 photomultiplier tubes (PMTs) that are individually coupled to a 6.25×6.25×25mm(3) LSO crystal. By analyzing waveform samples generated by using four thresholds, we obtain a coincidence timing resolution of about 340 ps and an ∼18% energy resolution at 511 keV. We are also able to estimate the decay-time constant from the resulting samples and obtain a mean value of 44ns with an ∼9 ns FWHM. In comparison, using digitized waveforms obtained at a 20 GSps sampling rate for the same LSO/PMT modules we obtain ∼300 ps coincidence timing resolution, ∼14% energy resolution at 511 keV, and ∼5 ns FWHM for the estimated decay-time constant. Details of the results on the timing and energy resolutions by using the multi-threshold method indicate that it is a promising approach for implementing digital PET data acquisition.

The role of P-glycoprotein/cellular prion protein interaction in multidrug-resistant breast cancer cells treated with paclitaxel

We previously reported that treatment with P-glycoprotein (P-gp) substrates promotes in vitro invasion in multidrug-resistant (MDR) breast cancer cells. This effect is initiated by the P-gp pump function and mediated by interaction of P-gp with some unknown component(s). However, the underlying mechanism(s) remains poorly understood. Here we confirm a novel physical interaction between P-gp and cellular prion protein (PrP(c)). Blocking P-gp activity or depletion of PrP(c) inhibited paclitaxel (P-gp substrate)- induced invasion. Paclitaxel further facilitated the formation of P-gp/PrP(c) clusters residing in caveolar domains and promoted the association of P-gp with caveolin-1. Both caveolin-1 and the integrity of caveolae were required for the drug-induced invasion. In addition, the P-gp/PrP(c) complex also played an important role in anti-apoptotic activity of MCF7/Adr cells.These data provide new insights into the mode by which MDR breast cancers evade cytotoxic attacks from P-gp substrates and also suggest a role for P-gp/ PrP(c) interaction in this process.

The Pd catalyst effect on low temperature hydrogen desorption from hydrided ultrathin Mg nanoblades

We present hydrogenation/de-hydrogenation properties of ultrathin Mg nanoblades coated with Pd as a catalyst. The hydrided Pd/Mg/Pd and Pd/Mg nanoblades were highly curved as observed by ex situ scanning electron microscopy. An in situ thermal desorption spectroscopy (TDS) study showed that the hydrided Pd/Mg/Pd nanostructure has a low hydrogen desorption temperature, at ∼365 K. Through a combinational microstructure and TDS analysis of hydrided Pd/Mg/Pd nanoblades as well as hydrided Pd/Mg/Pd nanoblades covered with an additional ultrathin Mg layer, we found that the effect of Pd catalyst on reducing the hydrogen desorption temperature is significantly stronger than the conventionally proposed mechanisms due to grain size and strain.

Expression of SRG3, a chromatin-remodelling factor, in the mouse oocyte and early preimplantation embryos

SRG3 (Smarcc1) is a core subunit of the SWI/SNF complex. In the absence of SRG3, embryonic development ceases during peri-implantation stages, indicating that SRG3, as well as the chromatin-remodelling process, plays an essential role in early mouse development. To gain a better understanding of chromatin remodelling during the early stages of development, we examined SRG3 expression during oogenesis and preimplantation stages using immunofluorescence and western blot assays. SRG3 was detected in nuclei of oocytes during growth and maturation. Following fertilization, SRG3 was detected in pronuclei shortly after their formation. Nuclear concentrations of SRG3 increased in a time-dependent fashion and were found to be greater in the male pronucleus than in the female pronucleus. The increase in nuclear SRG3 was partially inhibited by a protein synthesis inhibitor, but not by a transcriptional inhibitor. Expression of SRG3 is accompanied by expression of Brg1 and Ini1, two other core subunits of the SWI/SNF complex. The expression of these three remodelling factors parallels that of SP1 and TBP, both spatially and temporally, in the mouse embryo, suggesting a role for remodelling factors in chromatin structure and function during early development.

Reduction of forkhead box P3 levels in CD4+CD25high T cells in patients with new-onset systemic lupus erythematosus

The aim of this study was to quantify and evaluate the forkhead box P3 (FoxP3) expression regulatory T cells in new-onset systemic lupus erythematosus (SLE) patients before and after treatment. Forty-four newly diagnosed and untreated SLE patients, including 24 with active disease (SLEDAI > or = 10) and 20 with inactive disease (SLEDAI < 5), were enrolled in this study. Twenty-one age- and sex-matched healthy volunteers were also included as controls. Peripheral blood samples were collected and mononuclear cells isolated. The expression of CD25 and FoxP3 in CD4(+) T cells were analysed with flow cytometry. CD4(+)CD25(+) (3.95-13.04%) and CD4(+)CD25(high) (0.04-1.34%) T cells in peripheral blood in untreated patients with new-onset active lupus were significantly lower than that in the patients with inactive lupus (7.27-24.48%, P < 0.05 and 0.14-3.07% P < 0.01 respectively) and that in healthy controls (5.84-14.84%, P < 0.05). Interestingly, the decrease in CD4(+)CD25(high) T cells was restored significantly in patients with active lupus after corticosteroid treatment. There was, however, a significantly higher percentage of CD4(+)FoxP3(+) T cells in patients with active (5.30-23.00%) and inactive (7.46-17.38%) new-onset lupus patients compared with healthy control subjects (2.51-12.94%) (P < 0.01). Intriguingly, CD25 expression in CD4(+)FoxP3(+) T cells in patients with active lupus (25.24-62.47%) was significantly lower than that in those patients with inactive lupus (30.35-75.25%, P < 0.05) and healthy controls (54.83-86.38%, P < 0.01). Most strikingly, the levels of FoxP3 expression determined by mean fluorescence intensity in CD4(+)CD25(high) cells in patients with active SLE were significantly down-regulated compared with healthy subjects (130 +/- 22 versus 162 +/- 21, P = 0.012). CD4(+)CD25(high) T cells are low in new-onset patients with active SLE and restored after treatment. Despite that the percentage of CD4(+)FoxP3(+) T cells appear high, the levels of FoxP3 expression in CD4(+)CD25(high) T cells are down-regulated in untreated lupus patients. There is a disproportional expression between CD25(high) and FoxP3(+) in new-onset patients with active SLE.

Unusual magnesium crystalline nanoblades grown by oblique angle vapor deposition

We observed the growth of unusual Mg nanoblades by oblique angle deposition. Although the vapor flux is obliquely incident, these nanoblades stand vertically on the substrates. The thickness of the Mg nanoblades along the incident vapor direction is reduced to approximately 15 nm to -30 nm at a vapor incident angle approximately 75 degrees, while the width perpendicular to the incident vapor direction is as wide as a few hundred nm. In addition to the anisotropic blade morphology, a (1010) [0001] biaxial (II-O) texture was observed using in situ reflection high energy electron diffraction (RHEED). The tilt angles of the texture axis and the nanoblades are correlated with the high surface diffusion on the (0001) surface along the [2130] direction. We also propose that the observed very thin thickness of the nanoblade along the vapor flux direction is due to the appearance of the surface steps parallel to the [0110] direction and the low surface diffusion on the top surface of the nanoblades.

Adrenomedullin gene expression and peptide levels in the heart and blood vessels of streptozotocin-diabetic rats

The aim of the present study was to assess the changes in gene expression and peptide adrenomedullin (AM) levels in cardiovascular and other tissues in the streptozotocin-diabetic rats. For this purpose, diabetes was induced by intraperitoneal injection of streptozotocin (STZ, 65 mg/Kg body weight). Half of the diabetic rats were subcutaneously injected with insulin in the afternoon (4 units/day) one week after STZ injection until the day before killing. Control rats received only saline injection. AM mRNA was determined in cardiovascular and other tissues of streptozotocin-diabetic rats using solution-hybridization-RNase protection assay. Circulating AM and peptide AM in cardiovascular and other tissues were estimated using a specific radioimmunoassay. There were increases in preproAM mRNA levels in the left and right ventricles and in the thoracic aorta in both the 2-week and 4-week diabetic rats, but not in the two atria, the mesenteric artery and the lung. In the 2-week diabetic rats, there were decreases in AM contents in the two atria and the lung but an increase in the thoracic aorta. In the 4-week diabetic rats, there were bigger decreases in the atria and also a decrease in the left ventricle. The plasma AM levels were not changed but there was an increase in the excretion of AM in the urine. Our results suggest a possible increase in AM release in the heart and the thoracic aorta in the 2-week and 4-week diabetic rats.

Mechanism of neuroprotective effect induced by QingKaiLing as an adjuvant drug in rabbits with E. coli bacterial meningitis

OBJECTIVE

To explore the neuroprotective effects and underlying mechanism of QingKaiLing (QKL) as an adjuvant treatment for bacterial meningitis.

METHOD

E. coli bacterial meningitis rabbits were treated with antibiotics (ampicillin) alone or in combination with QKL. The number of leukocytes and the concentration of protein in the cerebrospinal fluid (CSF) of rabbits were determined at 0, 16, and 26 hours after treatment. Brain water, sodium, potassium, and calcium contents were determined at the 26-hour time point. The level of matrix metalloproteinase-9 in the brain was also determined by Western blot.

RESULT

The average number of leukocytes and the concentration of protein in CSF of the QKL adjuvant treatment group were reduced compared with the ampicillin alone group. Brain water, sodium, and calcium contents were reduced in the QKL adjuvant treatment group. The level of MMP-9 in brain tissue was also reduced in the QKL adjuvant treatment group.

CONCLUSION

QKL adjuvant treatment alleviates the aggravated inflammatory reaction and partially protects brain tissue from antibiotic-induced injury. The mechanism of this neuroprotective effect of QKL may be due to decreased levels of Ca2+ and MMP-9 in the brain.

Mechanical testing of isolated amorphous silicon slanted nanorods

Mechanical testing was performed on a new class of nanostructures-amorphous Si slanted nanorods of rectangular cross section, fixed at one end to the substrate. These nanorods were grown spatially well separated on nano-pillars under the oblique angle physical vapor deposition technique. Various samples with different dimensions and inclination angles were tested in bending using an atomic force microscope. The material response was elastic up to large stresses/deflections. The Young's modulus was calculated from the slope of the experimentally observed stiffness versus the geometrical factor common to all the samples and was found to be (94.14 +/- 10.21) GPa. No size effect of this parameter was observed within the accuracy of the present measurement.

Ether stress increases adrenomedullin gene expression and levels in the rat adrenal

To study the contribution of adrenomedullin in the adrenal medulla in the stress response, we measured plasma and adrenal levels of adrenomedullin in sham-operated (intact) rats and in rats without adrenal medulla, with or without exposure to ether vapor for 15 min. Adrenomedullin levels decreased drastically after demedullation. Effect stress resulted in increased adrenomedullin levels in both adrenal and plasma in sham-operated rats, but not in demedullated rats. The responses of plasma adrenocorticotropin to stress were similar, but the elevations in plasma corticosterone levels were significantly less in demedullated rats. In the sham-operated rat, preproadrenomedullin mRNA levels were increased after stress, and this effect was not blocked by pretreatment with hexamethonium. We conclude that stress increases adrenomedullin synthesis and secretion from the adrenal medulla through a hexamethonium-insensitive mechanism, and that adrenomedullin release from the adrenal medulla may play a role in cortical steroidogenesis.

HIV and syphilis in young Chinese adults: implications for spread

Our objective was to explore the epidemiology of HIV and syphilis at population level in young Chinese adults. The study was carried out in six areas of three Chinese provinces: Zhejiang, Yunnan and Shaanxi. All couples attending the compulsory premarital examination were recruited. Routinely taken blood was collected onto filter paper. Tests for HIV and syphilis used modified particle agglutination techniques. In all, 17,226 individuals were tested. There were no HIV infections in Zhejiang or Shaanxi. In Yunnan, there were 28 positives: 0.75% (95% confidence interval: 0.5, 1.1), with 22 (78%) in men and 16 (57%) in known high-risk individuals. Syphilis prevalence ranged from 0.33% to 0.71% across study sites, with 58% in men. Although syphilis levels suggest that unsafe sexual activity is occurring in all areas, HIV is not yet affecting the general population of Zhejiang or Shaanxi. The epidemic in Yunnan is being driven by injecting drug users, but there may now be transmission in the general population.

Increased adrenomedullin expression in lungs in endotoxaemia

Adrenomedullin (AM) is a peptide involved in cardiovascular homeostasis and in inflammation. We examined its expression in a rat model of endotoxaemia. Male Sprague-Dawley rats received intraperitoneal injection of 5 or 10 mg/kg lipopolysaccharide (LPS), or saline as control. Rats were killed at 1, 3, 6, 12 and 24 h after injection. LPS at 5 mg/kg, but not saline, increased plasma AM significantly at 3 h. At 10 mg/kg, plasma AM was raised at 3, 6 and 12 h. Immunoreactive AM concentration in lung increased after 5 or 10 mg/kg LPS, but not saline. PreproAM mRNA level in lung was significantly increased at 3 and 6 h. In conclusion, endotoxin stimulates the expression of AM in the lungs and increases its circulatory concentration. AM may be involved in the systemic response to sepsis.

Mechanics of patterned helical Si springs on Si substrate

The elastic response, including the spring constant, of individual Si helical-shape submicron springs, was measured using a tip-cantilever assembly attached to a conventional atomic force microscope. The isolated, four-turn Si springs were fabricated using oblique angle deposition with substrate rotation, also known as the glancing angle deposition, on a templated Si substrate. The response of the structures was modeled using finite elements, and it was shown that the conventional formulae for the spring constant required modifications before they could be used for the loading scheme used in the present experiment.

Behavioral and neurochemical characterization of transgenic mice carrying the human presenilin-1 gene with or without the leucine-to-proline mutation at codon 235

Human presenilin-1 (PS1) mutations are associated with the incidence of familial Alzheimer's disease. The present study evaluated the behavioral and neurochemical effects of the L235P mutation (substitution of leucine by proline at codon 235) of the human PS1 gene, which has been linked to a form of early-onset Alzheimer's disease. Except for a significant increase in the production of beta-amyloid-42, the mutant mice did not show any overt signs of Alzheimer-like neuropathology in the form of plaque formation, changes in choline acetyltransferase activity, or somatostatin content in the brain. Cognitive assays indicated that the mutation did not affect the acquisition or reversal of a spatial reference memory task in the water maze or performance on a spatial working memory task. In contrast, L235P PS1 transgenic mice exhibited a significant impairment in a test of spontaneous object recognition. This dissociation is suggestive of a preferential impairment of the extrahippocampal memory system and is consistent with what has been reported in another pathological mutation (substitution of leucine by valine at codon 286) of the PS1 gene.

Species and gender differences in the formation of an active metabolite of a substituted 2,4-thiazolidinedione insulin sensitizer

1. The metabolism of a substituted 2,4-thiazolidinedione (P1) with dual PPARalpha/gamma activity was evaluated in male and female rats, dogs and monkeys. A para-hydroxylated metabolite (M1) with potent PPARgamma-selective agonist, was a major circulating drug-related component in female rats, dogs and monkeys, but not in male rats (M1-to-P1 exposure ratio of <1, 3-5, 5 and 5-11 in male rat, monkey, female rat, and dog, respectively). 2. M1 (%) formed in vitro (5, 53, 57-65, 67 and 67% in male rat, monkey, female rat, dog, and human liver microsomes, respectively), rank ordered with M1 (%) formed in vivo (24-45, 53-57, 78, 75-85%, for male rat, monkey, female rat and dog, respectively, after oral administration of P1). 3. The plasma clearance of M1 was higher in male rats (32 ml min(-1) kg(-1) compared with 6, 7 and 2 ml min(-1) kg(-1) in female rat, male monkey and male dogs, respectively). 4. The low amounts of M1 observed in male rats, with the appearance of products of the cleavage of the propyl group between the phenyl groups was probably due to the presence of the sex-specific CYP2C11, which cleaves P1 at the propyl bridge. None of the CYPs present in female rats cleaved P1 at this site and M1 was only produced by CYP2C6. In humans, only CYP2C8 and the polymorphic CYP2C19 produced M1.

The effects of melatonin and Ginkgo biloba extract on memory loss and choline acetyltransferase activities in the brain of rats infused intracerebroventricularly with beta-amyloid 1-40

Intraventricular infusion of rats with beta-amyloid for 14 days resulted in memory deficit in the water maze as well as decreases in choline acetyltransferase activities and somatostatin levels in the cerebral cortex and hippocampus. These changes were not altered by daily intraperitoneal injection of 20 mg/Kg melatonin. Orally administered Ginkgo biloba extract, however, partially reversed the memory deficit and the decrease in choline actyltransferase activities in the hippocampus. The latter treatment failed to reverse the decrease in somatostatin levels. The results indicate that orally administered Ginkgo biloba extract can protect the brain against beta-amyloid from changes leading to memory deficit through its effect on the cholinergic system.

SNPCEQer: detecting SNPs in sequences generated by the Beckman CEQ2000 DNA Analysis System

SNPCEQer identifies and reports SNPs in sequences obtained from the Beckman CEQ2000 DNA Analysis System. SNPCEQer aligns sequences obtained using CEQ2000 heterozygote detection analysis and reports discrepancies between individual sequences and the consensus sequence it generates from this set as SNPs when the individual base calls have high-quality values. SNPCEQer reported comparable numbers of SNPs to the UNIX-based PolyPhred (148 vs. 165, respectively) in regions amplified from eight genes. A total of 21 different SNPs was discovered. Each gene region was analyzed in 96-306 samples. SNPCEQer was designed to operate from Windows NT, making SNP detection more accessible to users without UNIX systems. SNPCEQer is available free of charge at http://innovation.swmed.edu.

[Historical investigation of dentifrice in China]

A herbal literature survey was carried out on data concerning historical pharmacognostical changes of "dentifrice" in China and how diseases of the teeth and gums had been treated there in ancient times. It had been considered to be a matter of utmost importance that to prevent teeth from decaying, only the brushing of teeth with a toothbrush was necessary. Over time, various tooth agents have been found to treat oral diseases the teeth and gums. Glycyrrhizae Radix, Ginseng Radix, Scutellariae Radix, Menthae Herbal, and salt were widely used materials. Investigations from all approaches are being carried out to develop remedies for oral diseases, including Kampo medicine and the pharmacological effects of numerous crude drugs. When tracing the pharmacognostical changes of dentifrice in ancient China, we felt wonder at and admiration for the abundance of clinical experiences described in the old herbal and medical literature we researched.

[In vivo and in vitro effects of selenium-enriched garlic on growth of human gastric carcinoma cells]

OBJECTIVE

To compare the effects of selenium-enriched garlic (Se-garlic), garlic, Na2SeO3, and garlic + Na2SeO3 on growth of human gastric carcinoma cells.

METHODS

In vivo and in vitro assays were carried out in the cultured human gastric carcinoma cell line MGC803 transplanted in the nude mice by cell count, flow cytometry, Western blot and neoplasm volume measurement.

RESULTS

The inhibition effect of garlic was similar to that of Se-garlic, but Na2SeO3 was weaker than Se-garlic. Combination of garlic and Na2SeO3 was stronger than Se-garlic. In flow cytometry assay, the proportion of G1 phase was increased after 24 hour treatment of Se-garlic, garlic and Na2SeO3 in the non-synchronized cells. However, the proportion of S phase was increased in the synchronized cells. The proportion of G2 + M phase was increased both in non-synchronized and synchronized cells on treatment with the combination of garlic and Na2SeO3. The amount of Cdk2-CyclinE complex and Cdk4-CyclinD1 complex was decreased in all treated synchronized cells in immunoprecipitation and immunoblot assays. The growth of MGC803 tumor in male Balb/c nude mice was inhibited by administration of 1.67% of Se-garlic (Se 2 micrograms/g) in diet with an inhibition rate of 29.92% in tumor weight. Treatment of either 0.83% of Se-garlic or 1.67% of garlic or 4.38 micrograms/g of Na2SeO3 (Se 2 micrograms/g) could not appreciably inhibit the growth of tumor. Wrapping of a number of monocytes around the tumor was induced in 62.50% of tumors in 0.83% of the Se-garlic group.

CONCLUSION

In vitro, Se-garlic is able to inhibit the growth of MGC803 cell through action of garlic. In vivo, Segarlic is able to inhibit growth of MGC803 tumor in nude mice by being better than garlic and selenite.

Hyper-expression of human apolipoprotein E4 in astroglia and neurons does not enhance amyloid deposition in transgenic mice

Recent studies in mice have clearly demonstrated that eliminating Apo E alters the rate, character and distribution of A beta deposits. In the present study, we asked whether elevating the levels of Apo E can, in a dominant fashion, influence amyloid deposition. We expressed human (Hu) Apo E4 via the mouse prion protein promoter, resulting in high expression in both astrocytes and neurons; only astrocytes efficiently secreted Hu Apo E4 (at least 5-fold more than endogenous). Mice hyper-expressing Hu Apo E4 developed normally and lived normal lifespans. The co-expression of Hu Apo E4 with a mutant amyloid precursor protein (APP) (Mo/Hu APPswe) or mutant APP and mutant presenilin (PS1dE9) did not lead to proportional changes in the age of appearance, relative burden, character or distribution of A beta deposits. We suggest that these data are best explained by proposing that the mechanisms by which Apo E influences A beta deposition involves an aspect of its normal function that is not augmented by hyper-expression.