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PubMed1997

Vitamin D receptor genotypes and intestinal calcium absorption in postmenopausal women.

Several studies have shown that bone mass and bone turnover are genetically determined. This genetic component is thought to be mediated in part by polymorphisms at the vitamin D receptor (VDR) locus, even though the underlying molecular mechanisms are still unknown. To evaluate a possible site of differential action of the VDR gene alleles we examined their correlation with intestinal calcium absorption in 120 Caucasian postmenopausal women (aged 61 +/- 0.6 years). VDR gene polymorphisms for Apa I, Bsm I, and Taq I restriction endonucleases were assessed by Southern blotting analysis. The most common genotypes observed in our population were AaBbTt (37%), AABBtt (20%), aabbTT (15%), AabbTT (15%), and AABbTt (9%). Although there was some evidence of 13% higher lumbar BMD values in aabbTT genotype with respect to AABBtt genotype, this difference of approximately 0.1 g/cm2 did not reach statistical significance, possibly because of the limited number of observations. On the contrary, no relationship was found between genotypes and femoral neck BMD values. Intestinal calcium absorption was significantly lower in BB and tt genotypes than, in bb and TT genotypes, respectively, and in AABBtt genotype than in either aabbTT or AaBbTt genotypes (P = 0.0015 ANOVA). No significant differences in intact PTH, alkaline phosphatase, 25OHD3, and 1, 25(OH)2D3 were found among subjects with different VDR genotypes. These results are consistent with a possible role of VDR alleles on intestinal calcium absorption.

Aged↗
PubMed2006

Differential calcium signaling in dairy cows with specific CXCR1 genotypes potentially related to interleukin-8 receptor functionality.

Neutrophil migration and activation are critical components of innate immunity and are mediated by a variety of inflammatory mediators, which include interleukin-8 (IL-8) and epithelial-derived neutrophil activating peptide-78 (ENA-78). Limited knowledge on the expression of receptors for these inflammatory mediators (CXCR1 and CXCR2) in bovine, in addition to the association of a polymorphism (G-->C) in position +777 of the CXCR1 gene with impaired neutrophil function, prompted evaluation of CXCR1 and CXCR2 mRNA and protein expression, ligand binding affinity, and intracellular receptor signaling in neutrophils from cows with different CXCR1 genotypes. Initial observations revealed that overall IL-8 receptor numbers appeared to be lower in cows with a CC genotype compared to cows with a GG genotype. However, in the presence of SB225002, a CXCR2 inhibitor, CXCR1 affinity was about fivefold lower in cows with a CC genotype and may have resulted in an underestimation of receptor numbers in cows with this genotype. In addition, intracellular calcium ([Ca++]i) release was lower in cows with a CC genotype when cells were stimulated with IL-8 but not ENA-78. Furthermore, when neutrophils were stimulated with an optimal dose of IL-8 in the presence of SB225002, [Ca++]i release was lower in cows with a CC genotype, suggesting differential CXCR1 signaling among genotypes. These findings offer knowledge of the role that each of these receptors plays in the inflammatory response in the bovine and provide insight into the potential mechanisms that may be affected in neutrophils of cows with different CXCR1 genotypes.

Animals↗
PubMed1999

Polymorphic genotypes of the HRES-1 human endogenous retrovirus locus correlate with systemic lupus erythematosus and autoreactivity.

Antinuclear autoantibodies are a hallmark of systemic lupus erythematosus (SLE). Autoantibodies to HRES-1/p28, a 28 000 M(r) nuclear protein, commonly occur in patients with SLE. HRES-1 is a single-copy endogenous retroviral element mapped to human Chromosome 1 at q42. A polymorphic Hin dIII site defines two different allelic forms of the genomic locus. The HRES-1/1 probe [5.5 kilobases (kb)] anneals to three polymorphic fragments and three genotypes can be differentiated: I, 5.5 kb fragment only; II, 3.7 kb and 1.8 kb fragments only; and III, all three polymorphic fragments. By cloning of the HRES-1 locus from homozygous type I and type II human DNA samples, the polymorphic Hin dIII site was identified as a G to C transition at position 653 of the long terminal repeat region. Family studies showed that Hin dIII genotypes of the HRES-1 locus are inherited in a Mendelian pattern. The relative frequency of genotype I with respect to genotype III was 3.1-fold lower in patients with SLE (14:40=0.35) in comparison to 100 ethnically matched control donors (47:43=1.09; P=0.0084). Frequency of genotype I vs genotype II alleles was lower in SLE (68/52) than in normal donors (137/63; P=0.033), suggesting that a genotype I allele of the HRES-1 locus may be protective against SLE. Western blot seroreactivity with recombinant HRES-1/p28 was noted in 4/14 (29%) of genotype I patients and 13/19 (68%) of genotype III patients (P<0.025). These data raise the possibility that the HRES-1 element or a gene in linkage disequilibrium with this genomic locus may influence autoimmunity in SLE.

Adolescent↗
PubMed2005

Elevated risk of colorectal cancer associated with the AA genotype of the cyclin D1 A870G polymorphism in an Indian population.

PURPOSE: To investigate whether the common cyclin D1 (CCND1) A870G polymorphism is a risk factor for colorectal cancer (CRC) in an Indian population. METHODS: In this study, 301 newly diagnosed CRC patients and 291 healthy control subjects were genotyped by the PCR-RFLP method. Genotype frequencies were compared between cases and controls, and the association of genotypes with CRC was studied. RESULTS: The CCND1 870 A allele was more frequently observed in CRC patients than controls (0.63 vs. 0.56, P=0.01), and after adjustment for age, sex, smoking habits, family history, family income and the consumption of meat, fish, vegetables and fruit, an increased risk was observed for the AA genotype compared to the GG+AG genotype (OR=1.56; 95% CI: 1.10-2.21). The increased risk were also found for colon (OR=1.96; 95% CI: 1.08-3.57) and rectal cancer (OR=1.51; 95% CI: 1.04-2.19). No correlation was observed between genotypes and age of diagnosis of CRC (49.9, 48.7 and 49.4 years for the GG, AG and AA genotypes, respectively; P=0.84). Multivariate analysis also revealed a stronger positive association with the AA genotype among patients with high meat intake (OR=2.67; 95% CI: 1.29-5.51), and particularly significant inverse associations with the GG+AG genotypes were also found for those with high vegetable consumption (OR=0.46; 95% CI: 0.27-0.79 of 2-3 servings/day, and OR=0.31; 95% CI: 0.18-0.53 for >3 servings/day) and fish intake (OR=0.48; 95% CI: 0.28-0.82). CONCLUSION: These data support the hypothesis that the CCND1 A870G polymorphism may increase the risk of CRC in our Indian population.

Adult↗
PubMed2003

Identification of genotypes of Cryptosporidium parvum isolates from ferrets in Japan.

Recent molecular studies show that Cryptosporidium parvum is composed of at least eight genotypes including zoonotic genotypes. Therefore, it is important to screen the genotypes of the isolates harbored in animals for the control of human cryptosporidiosis. The ferret is a popular pet, but also a reservoir of Cryptosporidium. Since the infectivity of zoonotic genotypes in ferrets remains unclear, there is a possibility these hosts harbor zoonotic genotypes. In the present study, we examined the genotypes of C. parvum isolates from ferrets in Japan using polymerase chain reaction direct sequencing. The sequences of the isolates examined clustered with the ferret-adapted genotype (ferret genotype). Our study suggests that ferrets harbor the ferret genotype which is conserved across geographical areas. Further study is required to determine whether ferrets are a significant reservoir for human cryptosporidiosis.

Animals↗
PubMed2001

Molecular epidemiology of TT virus (TTV) and characterization of two novel TTV genotypes in Indonesia.

The prevalence of TT virus (TTV) DNA among 244 healthy individuals in 23 cities on 12 islands in Indonesia was determined by polymerase chain reaction (PCR) with primers derived from the coding region (N22), which can detect TTV DNA of genotypes 1-6. By N22 PCR, TTV DNA was detected in 102 (42%) individuals. The amplified PCR products were molecularly cloned and three clones each were subjected to sequence analysis. Three hundred one (98%) of the 306 TTV clones were classified into genotype 1, 2 or 3, and none into genotypes 4-6. The remaining five clones from two individuals (Kt-08 and Kt-10) on Kutai, Kalimantan Island, differed by >30% from known TTV isolates of all 21 genotypes and were tentatively classified into genotypes 22 and 23, respectively. Using primers specific for the new TTV genotype 22 or 23, TTV genotype 22 was detected significantly more frequently in Kutai than in the other 22 cities (41% vs. 5%, P < 0.001). TTV genotype 23 was restricted to Kutai (17% vs. 0%, P < 0.001), suggesting the indigenous nature of this genotype. Analysis of two TTV isolates (Kt-08F and Kt-10F) demonstrated the extreme diversity of TTV and the preservation of the genomic organization and transcription profile.

Adult↗
PubMed2003

Serotyping and genotyping of hepatitis C virus in Belgium.

BACKGROUND: Given that both pathogenicity and the response to treatment are possibly associated with hepatitis C virus (HCV) serotype, it appeared sensible to establish the prevalence of the different HCV types in Belgium. MATERIALS AND METHODS: The HCV serotypes were determined in 68 HCV-RNA and anti-HCV-positive samples taken from Belgian patients and compared with the results of the genotyping assay. Possible associations with age and sex were investigated. RESULTS: Antibodies were identified in 55 (80.9%) of the 68 samples, with serotype 1 (58.8%) and serotype 3 (19.1%) showing the highest prevalence. 17 samples contained several serotypes with serotype 1 being detected in 82.4% of cases. Nine of the 11 samples undetermined by serotyping could be determined by genotyping. There was no significant difference in the distribution of HCV types with respect to gender. Compared with genotype 3 (p < 0.01) and genotypes 2 and 4 (p = 0.05), genotype 1 was detected among older patients. CONCLUSION: Our data showed a 96.0% correlation between the serotyping and genotyping assays. Genotypes 1 and 3 are the most prevalent types among Belgian patients. The data suggest that genotype 1 spread earlier than genotypes 2, 3 and 4. This corroborates previous European studies.

Adult↗
PubMed1988

The influence of the genotype on the process of ageing of chick lens cells in vitro.

We reported previously that changes in crystallin expression in differentiating long-term primary cultures of lens cells from five different chick genotypes are similar to those which occur in vivo between hatching and the 8-week-old adult. These changes followed a similar program in all genotypes but occurred more rapidly in cells from the fast-growing than from the slow-growing genotypes. The present study examines ageing changes in lens cell populations from the same five genotypes, over a 4-6 month period, using long-term serial subcultures. The capacity for lentoid differentiation was progressively lost, but the rate of loss was inversely related to the intrinsic growth rate of the cells of these genotypes, occurring at the first passage in the slowest-growing strain, while fifth passage cells of the fastest-growing strain still retained some lentoid-forming capacity. The rate of loss of crystallin expression was also inversely related to the genetic growth rate, but the sequence of changes appears to be nonrandom, since it was broadly similar in all genotypes, starting with a preferential loss of delta-crystallin, as occurs in vivo; although alpha- and beta-crystallins were undetectable in late dedifferentiated cultures, the capacity of the cells for their synthesis was still present. Cultures from both fast-growing genotypes eventually showed senescence, but those from all three slow-growing genotypes underwent transformation. The major cell component in late cultures of all genotypes was actin.

Animals↗
PubMed1995

The changing relative prevalence of hepatitis C virus genotypes: evidence in hemodialyzed patients and kidney recipients.

BACKGROUND/AIMS: Hepatitis C virus (HCV) infection by the genotype 1b is significantly associated with a lower rate of response to interferon alfa and with severe liver disease (cirrhosis and hepatocellular carcinoma). This may reflect different intrinsic properties of this genotype 1b and/or chronological differences in the epidemiology of HCV genotypes. To address the issue of variations in genotypes prevalence, we studied in the present report the HCV genotypes of 60 hemodialyzed and kidney recipients according to the date of hemodialysis. METHODS: Anti-HCV antibodies were tested by a second-generation assay (enzyme-linked immunosorbent assay 2 and recombinant immunoblot assay 2). HCV RNA was detected by reverse-transcription polymerase chain reaction. Genotyping was performed by hybridization of type-specific probes to the amplified product from the 5' untranslated region. RESULTS: Genotype 1b accounted for more than two thirds of HCV infection in patients who underwent dialysis before 1977 but less than one third in those hemodialyzed after 1985. In contrast, other genotypes (3a, 4a, 5a) appeared in the 1980s. CONCLUSIONS: These data, obtained in an homogenous group of patients, show a changing pattern of HCV genotype prevalence over time and should be considered when discussing the potential clinical implications of HCV genetic variability.

Female↗
PubMed1996

A second-generation method of genotyping hepatitis C virus by the polymerase chain reaction with sense and antisense primers deduced from the core gene.

A second-generation method of genotyping hepatitis C virus (HCV) was developed by the polymerase chain reaction (PCR) with sense as well as antisense primers deduced from the core gene. HCV RNA specimens extracted from sera were reverse-transcribed and amplified with universal primers in the first round of PCR to obtain fragments of 433 base pairs representing nucleotides 319-751. In the second round of PCR, portions of PCR products were amplified separately with sense and antisense primers specific for each of the five common genotypes prevailing across the world, i.e., I/1a, II/1b, III/2a, IV/2b and V/3a. The specificity of the method was verified by a panel of 177 HCV isolates of various genotypes in the genetic groups 1-9. It allowed clear differentiation of genotype I/1a from II/1b which was not always accomplished by the previous method. When 501 sera from blood donors and hepatitis patients with HCV viremia from various countries were genotyped by the second-generation method, 478 (95.4%) were classified into the five genotypes. HCV RNA samples from 23 (4.6%) sera were not classifiable into any of the five common genotypes and, by sequence analysis, 22 were found to be of four genotypes in group 4 and one of genotype 1c in Simmond's classification.

Base Sequence↗
PubMed2026

Association of Enterocytozoon bieneusi Infection with chronic/persistent diarrhea and ITS genotypic diversity: a hospital-based case-control study in Suburban Shanghai, China.

Enterocytozoon bieneusi is a globally distributed zoonotic enteric pathogen that remains largely overlooked in routine diarrheal disease surveillance. Although previous studies in Shanghai, China, have reported elevated prevalence in diarrheal populations, case-control data from suburban areas at the peri&#x2011;urban interface and the strength of the association between E. bieneusi infection and chronic diarrhea in non-immunocompromised individuals remain poorly characterized. We performed a hospital-based case-control study in suburban Shanghai, enrolling 286 diarrheal outpatients without documented immunodeficiency and 138 asymptomatic controls frequency-matched for age and sex. Fecal specimens were collected and subjected to genomic DNA extraction. E. bieneusi was detected via nested PCR amplification of the ribosomal internal transcribed spacer (ITS) region. Factors associated with infection were identified using multivariate logistic regression. Genotypic diversity and zoonotic potential were assessed by Sanger sequencing and phylogenetic analysis. The overall prevalence of E. bieneusi was 12.2% (35/286) in diarrheal patients, significantly higher than the 2.2% (3/138) observed in asymptomatic controls (P < 0.001). E. bieneusi positivity was independently associated with chronic/persistent diarrhea (adjusted odds ratio = 2.63, 95% confidence interval: 1.25-5.54, P = 0.011). Fourteen distinct ITS genotypes were identified, comprising five known genotypes (D, EbpD, SHW7, Henan-III, and CHG5) and nine novel genotypes (designated SHH2 to SHH10). Thirteen genotypes clustered within Group 1, and one genotype (CHG5) fell within Group 2, two phylogenetic groups that contain genotypes with documented zoonotic potential in global surveillance. E. bieneusi was detected at a relatively high prevalence among diarrheal patients in suburban Shanghai, and its detection was associated with chronic/persistent diarrhea. The predominance of zoonotic genotypes and the identification of nine novel Group 1 genotypes indicate phylogenetic similarity to known zoonotic lineages and warrant further investigation of local zoonotic transmission; no animal or environmental samples were analyzed in this study. These findings suggest that E. bieneusi testing may be considered as part of the differential diagnosis for patients with unexplained chronic/persistent diarrhea and highlight the need for One Health surveillance in the surveyed area.

Diarrhea↗
PubMed2004

The increase in cholesterol with menopause is associated with the apolipoprotein E genotype. A population-based longitudinal study.

During menopause, a sharp increase in cholesterol concentration occurs with an unexplained wide variation in change. Possibly, this is attributable to genetic variation. The authors prospectively studied the effect of the apolipoprotein E (APOE) genotype on the change in cholesterol level with menopause among 1116 Dutch women. Women with the APOE3E3 genotype were regarded as the reference category and changes were adjusted for age at baseline, years of follow-up, years since menopause, and body mass index. At baseline, the women were on average 50.4 years. After 5.9 years of follow-up, the women were on average 4.3 years (S.D. 1.5 years) postmenopausal. The mean increase in cholesterol with menopause in women with the APOE3E3 genotype was 0.67 mmol/L (95% CI, 0.61-0.72 mmol/L). In women with the APOE2E3 genotype the increase in cholesterol was 0.44 mmol/L (CI, 0.32-0.56 mmol/L). The increase in cholesterol in women with the APOE3E4 genotype did not differ from the increase in women with the APOE3E3 genotype. These results show that the increase in cholesterol level with menopause is 30% lower in women with the APOE2E3 genotype when compared with women with the APOE3E3 genotype, indicating that the APOE genotype contributes to the variation in cholesterol increase with menopause.

Alleles↗
PubMed2005

Are effects of MTHFR (C677T) genotype on BMD confined to women with low folate and riboflavin intake? Analysis of food records from the Danish osteoporosis prevention study.

We have previously found BMD and fracture risk to be significantly associated with the MTHFR (C677T) polymorphism in healthy postmenopausal women in the first years after menopause. Since then, other cohort studies have suggested that sufficient intake of riboflavin and/or folate may have the potential to prevent development of low BMD in women with the TT genotype. This could to some extent explain why this polymorphism is associated with low BMD or fracture in some study populations and not in others. It would also indicate that fractures associated with the TT genotype could be preventable by vitamin B supplementation. We have, therefore, reviewed baseline food record data from our original study to determine if BMD and fracture associations with the MTHFR genotype depended on the intake of folate, riboflavin, or other members of the vitamin B complex, associated with homocysteine metabolism. We analyzed genotype, BMD, and dietary records from 1700 healthy postmenopausal women who participated in the DOPS study. For the assessment of fracture risk, we used longitudinal observations from 854 women in the control group who remained compliant with their initial allocation of no treatment. Riboflavin intake was significantly correlated with femoral neck (FN) BMD in women with the TT genotype (r = 0.24, P < 0.01). FN and lumbar spine (LS) BMD were only associated with the MTHFR genotype in the lowest quartile of riboflavin intake. At the FN, similar threshold effects were shown for folate, vitamin B12, and vitamin B6. Among these vitamin B complex members, stepwise regression analysis identified riboflavin as the only significant predictor of FN BMD in the TT genotype. In conclusion, we confirm reports that BMD in the MTHFR TT genotype is only significantly reduced in the lowest quartile of riboflavin, B12, B6, and folate intake, at least at the time of menopause. Vitamin B supplementation would only be expected to benefit BMD in about 2% of the population, i.e., those with the TT genotype and low vitamin B intake.

Bone Density↗
PubMed2006

Genotype analysis of Candida albicans isolates obtained from different body locations of patients with superficial candidiasis using PCRs targeting 25S rDNA and ALT repeat sequences of the RPS.

BACKGROUND: Several molecular biology-based genotyping techniques have been adapted for studying the molecular characteristics of Candida albicans strains, which constitute the majority of the etiologic agents in candidiasis. Recently, we reported a PCR system targeting 25S rDNA and ALT repeat sequences in the repetitive sequence (RPS) for genotyping of C. albicans. OBJECTIVE: To assess the potential of 25S rDNA and RPS-based genotyping for studying the molecular epidemiology of C. albicans, and define the genotypic relationship of C. albicans between invasive and non-invasive lesions in the same individual. METHODS: C. albicans strains were isolated from infected lesions and commensal sites, such as oral mucosa and/or feces, of patients with superficial candidiasis. The genomic DNAs were amplified by PCRs using P-I and P-II to determine the 25S rDNA- and RPS-based genotypes of the isolates. RESULTS: Genotype A:3 C. albicans constituted the majority of the isolates, followed by A:3/4 and B:3 C. albicans. There was usually one genotype of C. albicans per person. The genotypes of infected lesion isolates and non-infected oral mucosa and/or feces isolates were identical in the same individual, even in serially isolated C. albicans. CONCLUSION: The results indicate that our combined PCR technique using P-I and P-II is a potential tool for molecular typing of C. albicans, and reveal that the genotypes of isolates are identical in the same individual, independent of the infective and non-infective phases or the body location.

Adolescent↗
PubMed2004

Evidence for a relation between the viral load and genotype and hepatitis C virus-specific T cell responses.

BACKGROUND/AIMS: The reason why patients with hepatitis C virus (HCV) genotype non-1 infection respond better to antiviral therapy than patients with genotype 1 infection is not known. The aim of this study is to explore the relation between the viral genotype, viral load, and the endogenous T cell response. METHODS: The viral genotype, the viral load, and the endogenous proliferative T cell response to the non-structural 3 protein (NS3) was analysed using serum and peripheral blood mononuclear cells from 103 patients with chronic HCV infection. RESULTS: Among 71 nontreated patients a T cell response was more common among those infected by genotype 3, as compared to those infected with genotype 1 (P<0.05). Among 32 patients undergoing antiviral therapy, presence of a T cell response was more common in genotype non-1 infected patients than in those infected by genotype 1 (P<0.01). Presence of a T cell response was related to a more rapid viral clearance (P<0,05), a negative HCV RNA test at week 12 (P<0.05), and a shorter viral half-life (P<0.05). CONCLUSIONS: The presence of an NS3-specific T cell response is related to the viral genotype and to a more rapid clearance of HCV RNA during antiviral therapy.

Antiviral Agents↗
PubMed2004

Genotypic diversity of Salmonella Enteritidis isolates from sporadic patients in limited area during one year.

OBJECTIVES: Our aims were to investigate the genetic epidemiology of Salmonella enterica serovar Enteritidis (S. Enteritidis) isolates using computerized analysis of restriction enzyme cleavage patterns. METHODS: A total of 106 S. Enteritidis isolates which were collected in Hiroshima Prefecture, Japan in 2001 were tested by pulsed-field gel electrophoresis (PFGE) using BlnI and XbaI enzymes. PFGE profiles were analysed and compared by using Fingerprinting II software. RESULTS: BlnI PFGE analysis divided the isolates into 29 genotypes. At 90% similarity, BlnI cleavage grouped the isolates into 15 genotypes, while XbaI cleavage grouped them into only four. Two major clusters, each with a predominant genotype, were identified by BlnI cleavage at 42% similarity. In spite of the mixed circulation of the two predominant genotypes, one genotype for which a number of subtypes were detected was predominant during the first half of the year. In contrast, the other genotype, for which no variant subtypes were detected, followed during the latter half. The genotypes identified by computerized analysis matched well with those judged by visual inspection. CONCLUSIONS: The results confirmed the usefulness of PFGE performed with BlnI and of the Fingerprinting II software for the genotyping of S. Enteritidis. We think that the prevalent characteristics of the predominant genotypes detected here were related to the genetic variations of S. Enteritidis.

Bacterial Typing Techniques↗
PubMed2006

Hepatitis B virus genotypes and precore/core-promoter mutations in Tunisian patients with chronic hepatitis B virus infection.

OBJECTIVE: The aim of this study was to determine the frequency of genotype and precore/core-promoter mutations in chronic hepatitis B virus (HBV) infected individuals in Tunisia. METHODS: We studied 164 Tunisian patients (38 HBeAg-positive and 126 HBeAg-negative) with chronic HBV infection. Genotypes and precore/core-promoter mutations were studied using Inno-LiPA and Multiplex-PCR and PCR-RFLP methodology. RESULTS: Alanine aminotransferase (ALT) levels were higher in HBeAg-positive compared with HBeAg-negative patients (p<0.05). Patients with HBeAg-positive chronic hepatitis B were younger than HBeAg-negative chronic hepatitis B patients. The 164 genotypes were distributed as follows: 1 genotype A (0.6%), 1 genotype B (0.6%), 3 genotype C (1.82%), 139 genotype D (84.75%), and 20 mixed genotypes (12.2%). In the precore region (41.5%) of the patients had exclusively PC mutant and (50.9%) had a mixture of wild-type and variant sequences. PC variant was more commonly found in HBeAg-negative patients than in HBeAg-positive patients (94.5% vs. 87.8%), respectively. The mutations in the core promoter were more common in HBeAg-negative patients (65.4%) than in HbeAg-positive patients (18.2%). These results indicate that genotype D is predominant in Tunisia. Precore mutation occurred invariably among HBeAg-positive and HBeAg-negative patients, whereas core-promoter mutations were more frequently found in HBeAg-negative patients. CONCLUSION: Analysis of these mutants may prove useful for clinical evaluation and choice of therapy.

Adolescent↗
PubMed2006

Alteration of oxidative and carbohydrate metabolism under abiotic stress in two rice (Oryza sativa L.) genotypes contrasting in chilling tolerance.

Abiotic stress is a major limiting factor in crop production. Physiological comparisons between contrasting abiotic stress-tolerant genotypes will improve understanding of stress-tolerant mechanisms. Rice seedlings (S3 stage) of a chilling-tolerant (CT) genotype (CT6748-8-CA-17) and a chilling-sensitive (CS) genotype (INIAP12) were subjected to abiotic stresses including chilling (13/12 degrees C), salt (100mM NaCl), and osmotic (200mM mannitol). Measures of physiological response to the stresses included changes in stress-related sugars, oxidative products and protective enzymes, parameters that could be used as possible markers for selection of improved tolerant varieties. Metabolite analyses showed that the two genotypes responded differently to different stresses. Genotype survival under chilling-stress was as expected, however, CT was more sensitive to salt stress than the CS genotype. The CT genotype was able to maintain membrane integrity better than CS, perhaps by reduction of lipid peroxidation via increased levels of antioxidant enzymes during chilling stress. This genotype accumulated sugars in response to stress, but the accumulation was usually less than in the CS genotype. Chill-stressed CT accumulated galactose and raffinose whereas these saccharides declined in CS. On the other hand, the tolerance mechanism in the more salt- and water-deficit-tolerant CS may be associated with accumulation of osmoprotectants such as glucose, trehalose and mannitol.

Adaptation, Physiological↗