Modelling fruit microstructure.
Explore the source record for details and available documents.
Algorithms↗
Biomedical subjects
T A Nguyen
Publications and source records attributed to T A Nguyen.
Changing distribution of group A rotavirus G-types and genetic analysis of G9 circulating in Japan.
A total of 1,797 fecal specimens from infants and children with acute gastroenteritis in Japan from July 2000 to June 2003 were tested for group A rotavirus by ELISA, RT-PCR, RNA-PAGE and latex agglutination methods. Of these, 439 were found to be positive for group A rotavirus and this presented 24.4%. In 2000-2001, G1 was the most prevalent (45.5%) followed by G2 (32.5%), G3 (12.3%), G9 (5.9%) and G4 (2.6%). However, G2 was found predominant with 40% in the following year (2001-2002). Interestingly, G9 had a rapid increase of infection up to 17.8%. In 2002-2003, G3 dominated over other G-types with 34%. Another interesting feature of the study was the demonstration of great genetic diversity among G9 strains in Japan. Worth of note was the first prevalence pattern of rotavirus G-types with an increase of G2, G3 as well as G9 and a decrease of G1 during the 20 year-survey of rotavirus infection in Japan.
Antigens, Viral↗
Existence of multiple outbreaks of viral gastroenteritis among infants in a day care center in Japan.
A total of 921 fecal specimens collected from 44 infants in a day care center (DCC) in Tokyo, Japan during June 1999 to July 2000 were tested for the presence of rotavirus, norovirus, sapovirus, astrovirus and adenovirus by reverse-transcription-multiplex polymerase chain reaction (RT-multiplex PCR) and sequence analysis. Of 88 fecal specimens from infants with acute gastroenteritis, 51.1% (45) were found to be positive for diarrheal viruses. Astrovirus was the most prevalent (15.9%, 14 of 88), followed by norovirus GII (14.8%, 13 of 88), adenovirus (12.5%, 11 of 88), and sapovirus (2.3%, 2 of 88). Viral mixed infection accounted for 5.7% (5 of 88). Interestingly, 230 of 833 (27.6%) fecal specimens collected from asymptomatic infants were also infected with diarrheal viruses. Of these, astrovirus, norovirus GII, adenovirus and sapovirus were identified in 53, 46, 96 and 22 fecal specimens (23%, 20%, 41.7%, and 9.6%, respectively). Moreover, 13 of 833 (1.6%) normal specimens showed mixed viral infections. Surprisingly, no rotavirus (known as the most common causative agent of acute gastroenteritis in DCCs) was detected in those subjects. Another interesting feature was the demonstration of five separate outbreaks of acute gastroenteritis identified in a single DCC. Outbreak A was associated with both astrovirus serotype 1 and norovirus GII/3 (known as Toronto virus cluster); Outbreak B with adenovirus 12; Outbreak C with norovirus GII/4 (Lordsdale virus cluster); Outbreak D with sapovirus GIV and Outbreak E with astrovirus serotype 1. To our knowledge, this is the first proof of multiple outbreaks of viral gastroenteritis in Japanese infants in a single DCC. Our results confirm the presence as well as the importance of these viruses and warn of the threat they pose.
Adenovirus Infections, Human↗
Etiologic agents of acute gastroenteritis among Japanese infants and children: virus diversity and genetic analysis of sapovirus.
A total of 371 fecal specimens from infants and children with acute gastroenteritis in Maizuru, Tokyo and Osaka, Japan from July 2002 to June 2003 were tested for the presence of diarrheal viruses by reverse transcription-polymerase chain reaction (RT-PCR), reverse passive hemagglutination (PRHA), RNA-polyacrylamide gel electrophoresis (PAGE), latex agglutination and sequence analysis methods. Among diarrheal viruses detected, group A rotavirus was the most prevalent (42.2%) followed by norovirus (28.9%), group C rotavirus (8.4%), sapovirus (6.7%), adenovirus (5.3%) and astrovirus (0.9%), respectively. There was the high rate (7.6%) of viral mixed infections. Sapovirus was classified into 6 genotypes (GI/1, GI/4, GI/5, GI/6 and GII/1 and one novel tentatively called GII/5). It is noteworthy that genogroup II sapovirus can be classified into 5 genotypes. Our findings confirmed the presence of many diarrheal viruses co-circulating among Japanese infants and children and showed the great genetic diversity among sapoviruses.
Acute Disease↗
A novel RT-multiplex PCR for enteroviruses, hepatitis A and E viruses and influenza A virus among infants and children with diarrhea in Vietnam.
A novel reverse transcription-multiplex polymerase chain reaction (RT-multiplex PCR) assay that can detect enteroviruses, hepatitis A and E viruses and influenza A virus from various hosts (avian species, human, swine and horse) was developed. The identification of that group of viruses was performed with the mixture of four pairs of published specific primers (F1 and R1, P3 and P4, 2s and 2as, MMU42 and MMU43) for amplifying viral genomes and specifically generated four different amplicon sizes of 440, 267, 146 and 219 bp for enteroviruses, hepatitis A and E viruses and influenza A virus, respectively. A total of 276 fecal specimens (previously screened for rotavirus, adenovirus, norovirus, sapovirus and astrovirus-negative) from infants and children admitted into hospital with acute gastroenteritis in Ho Chi Minh city, Vietnam during October 2002 and September 2003 were collected and further tested for the presence of those viruses by RT-multiplex PCR. Enteroviruses were identified in 27 specimens and this represented 9.8%. No hepatitis A and E viruses and influenza A virus was found among these subjects. The sensitivity and specificity of RT-multiplex PCR were also assessed and demonstrated the strong validation against RT-monoplex PCR. Taken together, the findings clearly indicated that this novel RT-multiplex PCR is a simple and potential assay for rapid, sensitive, specific and cost-effective laboratory diagnosis to investigate molecular epidemiology of acute gastroenteritis caused by enteroviruses, hepatitis A and E viruses and influenza A virus. This report is the first, to our knowledge, detecting these kinds of viruses in diarrheal feces from infants and children in Vietnam.
Child↗
Genetic diversity of sapovirus in fecal specimens from infants and children with acute gastroenteritis in Pakistan.
A total of 517 fecal specimens collected from infants and children with acute gastroenteritis in Karachi city, Pakistan during 1990-1994 were examined for the presence of sapovirus by RT-PCR and sequence analysis methods. Sapovirus was identified in 17 of 517 (3.2%) specimens. Sapovirus was further clustered into three distinct genogroups (I, II and IV) and these presented 70.6%, 23.5% and 5.9%, respectively. Our results clearly indicated that sapovirus could be classified into 7 GI and 4 GII genotypes. It was noteworthy to point out that sapovirus detected among Pakistani infants and children with acute gastroenteritis demonstrated the great genetic diversity and presented novel sapovirus genotypes.
Acute Disease↗
Exhaled breath condensate pH is a robust and reproducible assay of airway acidity.
Exhaled breath condensate (EBC) pH is low in several lung diseases and it normalises with therapy. The current study examined factors relevant to EBC pH monitoring. Intraday and intraweek variability were studied in 76 subjects. The pH of EBC collected orally and from isolated lower airways was compared in an additional 32 subjects. Effects of ventilatory pattern (hyperventilation/hypoventilation), airway obstruction after methacholine, temperature (-44 to +13 degrees C) and duration of collection (2-7 min), and duration of sample storage (up to 2 yrs) were examined. All samples were collected with a disposable condensing device, and de-aerated with argon until pH measurement stabilised. Mean EBC pH (n=76 subjects, total samples=741) was 7.7+/-0.49 (mean+/-SD). Mean intraweek and intraday coefficients of variation were 4.5% and 3.5%. Control of EBC pH appears to be at the level of the lower airway. Temperature of collection, duration of collection and storage, acute airway obstruction, subject age, saliva pH, and profound hyperventilation and hypoventilation had no effect on EBC pH. The current authors conclude that in health, exhaled breath condensate pH is slightly alkaline, held in a narrow range, and is controlled by lower airway source fluid. Measurement of exhaled breath condensate pH is a simple, robust, reproducible and relevant marker of disease.
Acid-Base Equilibrium↗
Paclitaxel (Taxol) attenuates clinical disease in a spontaneously demyelinating transgenic mouse and induces remyelination.
Treatment with paclitaxel by four intraperitoneal injections (20 mg/kg) 1 week apart attenuated clinical signs in a spontaneously demyelinating model, if given with onset of clinical signs. If given at 2 months of age (1 month prior to clinical signs), disease was almost completely prevented The astrogliosis, prominent in our model, was reversed by paditaxel as determined by astrocyte counts and quantitation of GFAP. Electron microscopic examination of affected regions at 2.5 months demonstrated that the myelin was generally normal. By 4 months of age, demyelination was common in the superior cerebellar peduncle, maximal at 6 months, but continued to 8 months. In addition to myelin vacuolation and nude axons, the presence of many thin myelin sheaths suggested remyelination or partial demyelination. Although no evidence of oligodendrocyte loss was seen, nuclear changes were observed. To substantiate that remyelination was occurring, we measured MBP (18.5 kDa), MBP-exon II, Golli-MBP, TP8, Golli-MBP-J37, platelet-derived growth factor alpha (PDGFR alpha) and sonic hedgehog (SHH). Of these TP8, PDGFR alpha and SHH were up-regulated in the untreated transgenic. After paditaxel treatment, MBP-Exon II, TP8, PDGFR alpha and SHH were further up-regulated. We concluded that some of the effects of paditaxel were to stimulate proteins involved in early myelinating events possibly via a signal transduction mechanism.
Animals↗
Risk factors for HIV-1 seropositivity in drug users under 30 years old in Haiphong, Vietnam.
AIMS: To assess the prevalence of HIV infection among young drug users in Haiphong and, secondarily, to document the current patterns of drug use and sexual behavior in them. Design, setting and participants. A cross-sectional survey of drug users 15-30 years old, identified from police lists and by the snowballing method between March 15 and May 30, 1999, was conducted in Haiphong City. MEASUREMENTS: Subjects (n = 520: 514 males and six females) were interviewed and donated blood specimens for HIV-1 antibody testing. FINDINGS: Mean age of the subjects was 25 years (range 15-30 years). The prevalence of HIV among injecting drug users (IDUs) was 74% and among drug users not reporting injecting was 46% (92/201). Sixty-one per cent (319) reported injecting drugs. Among injectors, 72% used heroin, and 68% had shared needles. Factors related to the presence of HIV antibody among IDUs were sharing needles (OR: 4.12) and injecting more than 31 times per month (OR: 2.37). Extramarital sex within the last 6 months was reported by 44% of single and 24% of married IDUs. CONCLUSION: The high HIV-1 prevalence in drug users and their frequent sexual mixing with the non-drug-using population suggests that preventive interventions for reduction of high-risk drug taking and sexual activities are urgently needed in these populations. Interventions through public sexually transmitted infection (STI) clinics are unlikely to have much impact, as only 16% of IDUs with an STI attended a public STI clinic.
Adolescent↗
Importance of gender and sex hormones in regulation of susceptibility of the small intestine to peroral infection with Toxoplasma gondii tissue cysts.
This study was performed to investigate whether the gender and sex hormones play a role in susceptibility of the small intestine of mice to peroral infection with Toxoplasma gondii tissue cysts. Female animals died significantly earlier than males, and early mortality of females was associated with greater numbers of tachyzoites and severe necrosis in their small intestines. Treatment of female mice with testosterone resulted in markedly reduced intestinal parasite numbers and pathology. Thus, the gender and sex hormones are important factors for determining susceptibility of the small intestine to T. gondii infection.
Animals↗
Single-residue alteration in alpha-conotoxin PnIA switches its nAChR subtype selectivity.
alpha-Conotoxins are disulfide-rich peptides that are competitive antagonists of nicotinic acetylcholine receptors (nAChRs). Despite their small size, different alpha-conotoxins are able to discriminate among different subtypes of mammalian nAChRs. In this report, the activity of two peptides from the venom of Conus pennaceus, alpha-conotoxins PnIA and PnIB, are examined. Although the toxins differ in only two residues, PnIA preferentially blocks alpha3beta2 nAChRs, whereas PnIB prefers the alpha7 subtype. Point mutation chimeras of these alpha-conotoxins were synthesized and their activities assessed on Xenopus oocytes expressing specific nAChRs. Change of a single residue, Ala10 to Leu, in PnIA (to form PnIA [A10L]) converts the parent peptide from alpha3beta2-preferring to alpha7-preferring; furthermore, PnIA [A10L] blocks the alpha7 receptor with an IC(50) (12.6 nM) that is lower than that of either parent peptide. Kinetic analysis indicates that differences in affinity among the analogues are primarily due to differences in off-rate, with PnIA [A10L]'s interaction with alpha7 having the smallest off-rate (k(off) = 0.17 min(-)(1)). Thermodynamic analysis indicates that Leu10 enhances the peptide's interaction with alpha7, but not alpha3beta2, receptors, whereas Ser11 (in PnIA [N11S]) reduces its affinity for both alpha7 and alpha3beta2 nAChRs.
Amino Acid Sequence↗
Interactions of nuclear receptor coactivator/corepressor proteins with the aryl hydrocarbon receptor complex.
MCF-7 human breast cancer cells express the aryl hydrocarbon receptor (AhR), and treatment with AhR agonists such as 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) inhibits estrogen receptor (ER)-mediated responses. This study investigates physical and functional interactions of the AhR complex with a prototypical coactivator (estrogen receptor associating protein 140, ERAP 140) and corepressor (silencing mediator for retinoic acid and thyroid hormone receptor, SMRT) for ER and other members of the nuclear receptor superfamily. The AhR, AhR nuclear translocator (Arnt), and AhR/Arnt proteins were coimmunoprecipitated with 35S-ERAP 140 and 35S-SMRT and, in gel mobility shift assays, AhR/Arnt binding to 32P-dioxin response element (DRE) was enhanced by ERAP-140 and inhibited by SMRT; supershifted bands were not observed. In transactivation assays, coactivator and corepressor proteins enhanced or inhibited AhR-mediated gene expression; however, these responses varied with the amount of coactivator/corepressor expression. These results confirmed functional and physical interactions of AhR/Arnt with ERAP 140 and SMRT in breast cancer cells.
Adaptor Proteins, Signal Transducing↗
The developmental expression and activity of peptidylarginine deiminase in the mouse.
We have measured the expression and activity of peptidylarginine deiminase (PAD, EC 3.5.3.15), the enzyme responsible for converting arginyl residues in proteins to citrullines, in normal mouse brain homogenate. PAD transcripts were detected as early as five days and were maximal at one month of age. The enzyme protein was also detected at 5 days in an antibody dependent assay and was maximal at 2 months of age, 1 month later than the maximum expression of transcripts. As expected, enzyme activity had a similar developmental profile to that of the enzyme protein. In isolated mouse brain compact myelin, the activity was highest at 15 days and fell rapidly to 15% of this level by 1-2 months. In the 'loose' myelin fraction (heavy myelin) it remained at the same high level form from 15 days to 8 months. The activity in compact myelin was about 15 times greater than the activity in brain homogenate, suggesting much of the enzyme was localized to myelin.
Animals↗
TNF-alpha, nitric oxide and IFN-gamma are all critical for development of necrosis in the small intestine and early mortality in genetically susceptible mice infected perorally with Toxoplasma gondii.
We previously reported that genetic susceptibility of mice to peroral infection with T. gondii is associated with CD4+ T cell-dependent, interferon (IFN)-gamma-mediated necrosis of their small intestine. We examined the role of tumour necrosis factor (TNF)-alpha and nitric oxide (NO), in addition to IFN-gamma. At 7 days after infection, a marked increase in CD4+ T cells was observed in lamina propria mononuclear cells (LPC) of the small intestine as compared with normal mice, and significantly greater amounts of mRNA for IFN-gamma, TNF-alpha, and inducible NO synthase (iNOS) were detected in LPC of the small intestine of infected than uninfected animals. Treatment of infected mice with anti-TNF-alpha monoclonal antibody (mAb) or the iNOS inhibitor, aminoguanidine, prevented necrosis and prolonged time to death. Infected iNOS-targeted mutant mice did not develop the disease whereas infected, control mice did. Treatment with anti-TNF-alpha mAb did not affect the expression of IFN-gamma in the LPC but inhibited expression of iNOS in the infected mice, indicating the role of TNF-alpha in the induction of iNOS. These results suggest that NO induced by a combination of IFN-gamma and TNF-alpha through activation of iNOS is a critical mediator of intestinal pathology and contributes to early mortality in genetically susceptible mice.
Administration, Oral↗
A comparative study of ofloxacin and cefixime for treatment of typhoid fever in children. The Dong Nai Pediatric Center Typhoid Study Group.
BACKGROUND: Despite concerns about safety in children, fluoroquinolone antibiotics have become the treatment of choice in patients with multidrug-resistant typhoid fever in Vietnam. However, quinolone-resistant strains of Salmonella typhi have recently been reported from Vietnam; and if quinolone resistance becomes established, alternative oral treatment options will be needed. OBJECTIVE: Cefixime, an orally administered third generation cephalosporin, was compared with ofloxacin for the treatment of uncomplicated typhoid fever in children. METHODS: In an open trial children with suspected typhoid fever were randomized to receive either ofloxacin (10 mg/kg/day in two divided doses) for 5 days or cefixime (20 mg/kg/day in two divided doses) for 7 days. RESULTS: S. typhi was isolated from 82 patients (44 in the cefixime group, 38 in the ofloxacin group) and 70 (85%) of the isolates were multidrug-resistant. Median (95% confidence interval, range) fever clearance times were 4.4 (4 to 5.2, 0.2 to 9.9) days for ofloxacin recipients and 8.5 (4.2 to 9, 1.8 to 15.2) days for cefixime-treated patients (P < 0.0001). There were 11 treatment failures (10 acute and one relapse) in the cefixime group and 1 acute treatment failure in the ofloxacin group (mean difference, 22%; 95% confidence interval, 9 to 36%). CONCLUSION: Short course treatment with cefixime may provide a useful alternative treatment in cases of uncomplicated typhoid fever in children, but it is less effective than short course treatment with ofloxacin.
Adolescent↗
Regulation of proximal tubular osteopontin in experimental hydronephrosis in the rat.
BACKGROUND: Osteopontin is a tubular-derived glycoprotein with macrophage chemoattractant properties. Our previous observations demonstrate that osteopontin is involved in the accumulation of macrophages within the renal cortex of rats following unilateral ureteral obstruction (UUO). METHODS: The present study performed Northern and Western blot analyses of isolated proximal tubular cells exposed to exogenous angiotensin II, and cultured rat proximal tubular cells subjected to one hour of cyclic mechanical stretch, which provided insight into mechanisms involving the proximal tubular renin-angiotensin system in the increased expression of cortical osteopontin following hydronephrosis. RESULTS: In situ hybridization, using a 35S-labeled antisense riboprobe, showed osteopontin mRNA transcription localized to the cortical tubules of the obstructed kidney. Freshly isolated proximal tubules incubated with angiotensin II (10-5 M) for one hour had increased osteopontin mRNA and protein expression by Northern and Western blot analyses, respectively. Pre-treatment of proximal tubules with losartan (10-5 M) for one hour prior to the addition of exogenous angiotensin II (10-5 M) decreased osteopontin mRNA and protein expression. Rat proximal tubule cells subjected to cyclic mechanical stretch for one hour exhibited a 2.1-fold increment in osteopontin mRNA levels, which was normalized following pre-treatment with losartan. CONCLUSIONS: This study provides evidence that angiotensin II, produced by the proximal tubule in the obstructed kidney as a result of mechanical injury, possibly mechanical stretch, may stimulate angiotensin II type I receptor activation, leading to up-regulated osteopontin expression and secretion by the proximal tubule, thereby facilitating macrophage recruitment into the renal interstitium.
Animals↗
Endoscopic management of urolithiasis in the morbidly obese patient.
A retrospective review of 48 consecutive morbidly obese patients with urolithiasis who were treated successfully by endoscopic modalities over 3.5 years was performed. Of the 73 endoscopic procedures, 48 were ureteroscopic laser lithotripsy (UL), 4 were ureteroscopic basket extraction, and 21 were percutaneous nephrolithotripsy (PCNL). The patients' weight ranged from 205 to 385 lbs. (average 286 lbs.). Their abdominal girth ranged from 53 to 65 inches (average 59 inches). Twenty-six patients had one procedure, eight patients had bilateral procedures, eleven patients had two procedures, and three patients had three procedures with utilization of either multiple ureteroscopic treatments or the combination of percutaneous and ureteroscopic techniques. The stone-free rate after one procedure was 77.8% for UL and 60% for PCNL. The stone-free rate after planned repeat procedures was 97% for UL/UL and 89% for PCNL/UL. There were two minor complications. Forty-eight procedures were performed on an outpatient basis, and the remaining 25 procedures necessitated hospital admission (average 3.6 days). Morbidly obese patients with urolithiasis who are unable to have SWL because of their body weight and abdominal girth can be treated successfully with UL, ureteroscopic basket extraction, and PCNL with efficacy comparable to that in patients of normal weight and with minimal morbidity. Many renal calculi were treated with UL alone with a high success rate.
Adult↗
Alpha-conotoxin MII blocks nicotine-stimulated dopamine release in rat striatal synaptosomes.
Activation of presynaptic nicotinic acetylcholine receptors (nAChRs) can induce the release of neurotransmitters such as dopamine and norepinephrine in the CNS. Accumulating evidence suggests that distinct nAChR subtypes are involved; however, it has been difficult to determine the subunit composition of these receptors, in part because of the lack of a sufficient variety of selective nAChR ligands. We present experimental data that at least two different nAChR complexes are involved in dopamine release, one of which has an alpha3/beta2 subunit interface. The recently discovered peptide alpha-conotoxin MII is a potent and selective inhibitor of rat nAChRs containing an interface formed by alpha3 and beta2 subunits. We used this peptide to examine nicotine-stimulated release of dopamine from rat striatal synaptosomes and of norepinephrine from hippocampal synaptosomes. MII (100 nM) blocks 34-49% of the nicotine-stimulated dopamine release, but not dopamine release evoked by elevated [K+]. Furthermore, two peptides structurally related to alpha-conotoxin MII, namely alpha-conotoxin MI (selective for alpha1beta1gammadelta nAChRs) and alpha-conotoxin ImI (selective for alpha7-containing nAChRs), have no effect on nicotine-stimulated dopamine release. The results indicate that one third to half of the dopamine release in the striatal preparation is mediated by nAChRs with an alpha3/beta2 subunit interface. In contrast, </=10% of nicotine-stimulated release of norepinephrine from hippocampal synaptosomes is modulated by nAChRs with alpha3/beta2 subunit interfaces.
Animals↗