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Biomedical subjects

H F Liu

Publications and source records attributed to H F Liu.

At least 19 recordsLinked to original sources
PubMed2001

Sequence polymorphism in the coding region of mitochondrial genome encompassing position 8389-8865.

Analysis of the polymorphic sequences in mitochondrial DNA (mtDNA) has been widely applied to forensic tests and anthropology studies. However, these polymorphic data in human have thus far been derived from the displacement-loop and intergenic regions only. Here, we report the identification of clustered polymorphic sites in the mitochondria coding region encompassing position 8389-8865. The DNA sequences of 119 unrelated Chinese were determined by PCR amplification and direct sequencing. The results showed that heteroplasmy was found in five individuals, 39 sites were noted in this 477 bp region, and 41 haplotypes were identified. The probability of identity and allelic diversity were estimated as 0.1265 and 0.8809, respectively. The results suggest that sequence polymorphism from position 8389-8865 in human mtDNA can be used as a marker for identity investigation.

DNA, Mitochondrial↗
PubMed2001

Wide variety of genotypes and geographic origins of hepatitis B virus in Belgian children.

BACKGROUND: Belgium is a country with low endemicity for hepatitis B virus (HBV) infection. Few data are available on genotypes or serotypes of HBV among infected children. METHODS: The S region of the hepatitis B virus genome was amplified and sequenced in 23 children treated with interferon-alpha in Belgium. Nucleotide sequences were aligned and compared with other known sequences in a phylogenetic analysis. RESULTS: A high stability of the S gene was observed during treatment. Four genotypes were represented in this sample of Belgian patients (A, B, D, and E), reflecting the geographic diversity of origins. CONCLUSIONS: In this series, the wide variety of geographic origins is confirmed by the molecular characteristics of HBV. In Belgium, HBV infection of children is currently essentially an imported infection.

Antiviral Agents↗
PubMed2001

The promoter region of the CTLA4 gene is associated with type 1 diabetes mellitus.

The CTLA4 (cytotoxic T lymphocyte associated antigen-4) gene encodes the T cell receptor involved in the control of T cell proliferation and mediates T cell apoptosis. C-T polymorphism is present at position -318 from the ATG start codon in the promoter region of the gene. We report a study on the polymorphism in 347 unrelated children with type 1 diabetes mellitus (DM) (age at diagnosis 7.2+/-3.8 years) and their 260 healthy siblings as controls. Genotype C/C conferred a risk of type 1 DM (RR = 2.02, 95% CI 1.32-3.10, pc = 0.0033). The gene frequency of the C allele was higher in patients (RR = 1.91, 95% CI 1.28-2.84, pc = 0.0026). The gene frequency and phenotype frequency of the T allele were negatively associated with type 1 DM (RR = 0.52, 95% CI 0.35-0.78, pc = 0.0026 and RR = 0.49, 95% CI 0.32-0.76, pc = 0.0022, respectively). The frequency of genotype C/T was lower in patients (RR = 0.50, 95% CI 0.32-0.78, pc = 0.0051). This study demonstrates that nucleotide -318 C-T polymorphism of the CTLA4 gene is associated with type 1 DM. The promoter allele -318 C confers a risk of type 1 DM but allele -318 T confers protection against this disease.

Abatacept↗
PubMed2001

[Intrathecal injection of NOS antisense oligonucleotides inhibits the increase of NMDA1AR mRNA expression in the spinal cord and brainstem of morphine-withdrawal rats].

Methods of reverse transcription polymerase chain reaction (RT-PCR), intrathecal injection and antisense drugs were used to study the effects of nitric oxide (NO) on the scores of morphine-withdrawal syndrome and the expression of NMDA1AR mRNA in rat spinal cord and brainstem. Intrathecal injection of NOS antisense oligonucleotides (AS-ONs) significantly decreased the scores of morphine-withdrawal symptoms. The effect of nNOS AS-ONs was greater than that of eNOS AS-ONs. The expression of NMDA1AR mRNA in the spinal cord and brainstem increased in morphine-dependent rats and increased to a greater extent in morphine-withdrawal rats. Intrathecal injection of nNOS AS-ONs significantly inhibited the increased expression of NMDA1AR mRNA in the spinal cord and brainstem of morphine-withdrawal rats. Intrathecal injection of eNOS antisense oligonucleotides inhibited the expression of NMDA1AR mRNA in the spinal cord of morphine-withdrawal rats, but did not in the brainstem. It is suggested that NO mediates morphine-withdrawal reaction and participates in modulating the expression of NMDA1AR mRNA in morphine-withdrawal rats.

Animals↗
PubMed2000

G protein beta3 subunit variant and essential hypertension in Taiwan - a case-control study.

Recent studies have shown that a C825T polymorphism of the gene encoding the G protein beta3 subunit contributes to the genesis of essential hypertension. However, the link between the gene and blood pressure is not consistently found in different populations. The aim of the present study is to investigate this issue in Taiwan. We analyzed the allelic status in 302 hypertensive (age, 60+/-11 years; male/female, 136/166) and 199 normotensive subjects (62+/-15 years; male/female, 90/109). Our result showed that the T allelic was more frequently seen in the hypertensive group than the normotensive, but the difference did not reach statistic significance (56.5 vs. 54.3%, P>0.1). Subsequent analysis demonstrated a similar trend in the female (58.7 vs. 53.7%, P>0.1) but a reverse trend in the male (53.7 vs. 55%, P>0.1). Another finding was that the T allele frequency in all the groups was over 50%, markedly higher than those reported in whites. In conclusion, the observation suggests that the polymorphism in the G protein gene is not likely to play an important role in the manifestation of high blood pressure in Taiwan.

Age Distribution↗
PubMed2000

High prevalence of GB virus C/hepatitis G virus in Kinshasa, Democratic Republic of Congo: a phylogenetic analysis.

A prevalence of 10.3% of GB virus C (GBV-C)/hepatitis G virus (HGV) carriers was found in 97 pregnant women from Kinshasa, Congo (formerly Zaire), while prevalences of 1%, 4.1%, and 0% were found for hepatitis C virus, human immunodeficiency virus, and human T-lymphotropic virus respectively. Phylogenetic analysis of the ten GBV-C/HGV positives based on the 5' non-coding region using three different methods identified consistently three GBV-C/HGV genotypes. Four main clades were found within the type 1 sequences. All the Congolese isolates are GBV-C/HGV type 1 in two different clades. The clustering of seven Congolese isolates was inconsistent in different methods. Further likelihood-mapping analysis showed a well-resolved phylogeny, confirming the clustering of the seven Congolese isolates with a Belgian strain representing a new clade in the GBV-C/HGV type 1 sequences.

Deltaretrovirus Infections↗
PubMed2000

[Characteristics and effect of allergic rhinitis in aircrew on flight].

OBJECTIVE: To observe the characteristics of allergic rhinitis in aircrew and its effect on flight. METHOD: Case studies of allergic rhinitis were made in 32 aircrew. RESULT: There were 20 cases of perennial allergic rhinitis and 12 cases of seasonal allergic rhinitis in 32 aircrew. Twenty-six cases are still in a qualified position to continue their flying job and the other six cases were permanently grounded. CONCLUSION: Allergic rhinitis in aircrew may affect the flying in aviation or space flight and the flying in aviation or space may induce or aggravate allergic rhinitis.

Adult↗
PubMed1999

Influence of CD4+ lymphocyte counts on GB virus C/hepatitis G virus carriership in HIV-positive individuals.

The duration of the GB virus C or hepatitis G virus (GBV-C/HGV) carriership varies according to the patient group studied. The immune competence of the host may be important. GBV-C/ HGV was studied in human immunodeficiency virus (HIV)-infected persons and an attempt was made to correlate the presence of viral RNA or E2 antibodies with CD4+ lymphocyte counts. Of 138 HIV-positive subjects, 30 were GBV-C/HGV RNA-positive and 20 others were E2 antibody-positive, whereas in healthy GBV-C/HGV-infected persons, the proportion of E2 antibody carriers was much higher. On the other hand, a relationship was not found between CD4+ lymphocyte counts and the presence of GBV-C/HGV RNA in the HIV-infected persons. This result does not necessarily imply that the CD4+ lymphocyte count does not affect viral clearance, but the results could be due to the trans-sectional nature of this study. A longitudinal assessment should clarify this point.

CD4 Lymphocyte Count↗
PubMed1999

The discovery of two new divergent STLVs has implications for the evolution and epidemiology of HTLVs.

We have isolated and characterised two divergent simian T-lymphotropic viruses (STLV), not belonging to the established human and simian T-lymphotropic virus lineages HTLV-1/STLV-1 and HTLV-2. STLV-L, from an Eritrean sacred baboon (Papio hamadryas), has been typed as a third type of simian T-lymphotropic virus, distinct from HTLV-1/STLV-1 and HTLV-2. The other virus, isolated from Congolese bonobos (Pan paniscus), is a distinct member of the HTLV-2 clade and has been designated STLV-2. The isolation of these two simian viruses shows that the spectrum of HTLVs/STLVs is larger than previously expected. Our data indicate that the two lineages STLV-L and HTLV-2/STLV-2 are of African origin, while the HTLV-1/STLV-1 lineage has been shown to be of Asian origin. These data, together with our phylogenetic analyses, suggest an African origin of the HTLV/STLV ancestor, which provides new clues about virus dissemination. Furthermore, the atypical serological profiles exhibited by STLV-L or STLV-2 infected animals in western blot, raise questions about the efficiency of current screening methods to type highly divergent HTLVs/STLVs. Considering the growing interest in xenotransplantations, more epidemiological and biological knowledge of simian and human T-lymphotropic viruses is necessary to estimate the risk of interspecies transmissions.

Animals↗
PubMed1999

Expression and purification of recombinant human zona pellucida proteins.

Recombinant human zona pellucida (rhZP) proteins (minus the N-terminal leader and the C-terminal transmembrane-like domain) were expressed in four different expression systems: bacteria, yeast, insect cells, and Chinese Hamster Ovary (CHO) cells. The recombinant proteins in each system were engineered with a C-terminal six histidine (His6) segment that was used to purify the proteins by metal affinity [either nickel (Ni) or cobalt (Co)] column chromatography. Each of the rhZP proteins was a candidate antigen as an immunocontraceptive vaccine. However, the rhZP proteins produced in bacteria, yeast and insect cell culture could only be purified after being solubilized by strong denaturants. After purification the final products of each of these expression systems required 6 M urea to maintain solubility. However, the rhZP proteins expressed by CHO cells were secreted into the media, and the soluble proteins could be purified to near homogeneity. In this report the expression and purification procedures used to produce and isolate these secreted proteins are described.

Animals↗
PubMed1999

Prevalence of GB virus C/hepatitis G virus among blood donors in north-eastern Brazil.

We tested 70 blood donors from Fortaleza (Ceara state, Brazil) for GB virus C/hepatitis G virus (GBV/HGV) infection by polymerase chain reaction and detection of antienvelope antibodies. Twenty-seven (38.6%) showed signs of an active or resolved infection. Sixty-four percent of those with indications of other blood-borne viral infections showed signs of GBV-C/HGV infection also.

Blood Donors↗
PubMed1998

The simian T-lymphotropic virus STLV-PP1664 from Pan paniscus is distinctly related to HTLV-2 but differs in genomic organization.

We have isolated a highly divergent simian T-lymphotropic virus, STLV-PP1664, from a wild-caught bonobo (Pan paniscus). Previous phylogenetic analysis suggested that this virus represents an additional type of STLV but this has now become a matter of discussion. We have now obtained and analyzed the entire genome of STLV-PP1664. All major genes and their corresponding viral messengers were identified. Sequence comparison and phylogenetic analysis indicated that this virus, together with the closely related panp isolate, belongs to an early lineage within the PTLV-2 clade, differing from HTLV-2 by about 25%. In contrast to the HTLV-1 and HTLV-2 LTR, only two 21-bp repeats instead of three were found in the STLV-PP1664 LTR. Additional messengers, resulting from alternative splicing, potentially encode five different accessory proteins from open reading frames in the pX region: prorfI, porfII, ptorfV', and two isoforms of Rex. The amino acid sequences of these proteins are only distinctly related to the accessory proteins from HTLV-2. These data suggest a different genomic organization of the STLV-PP1664 pX region than that of HTLV-2. We conclude that STLV-PP1664, although related to HTLV-2, has some distinct features in the LTR and the pX regions, the impact of which needs further investigation. Although arguments pro and contra a distinct classification are nearly equally balanced, we propose to classify this virus as an STLV-2, designated STLV-2PP1664.

Amino Acid Sequence↗
PubMed1998

GB virus C: a novel pathogen or a curiosity for virologists?

The recently identified GB virus C is a flavivirus related to the hepatitis C virus. It appears quite prevalent in the general population and especially in individuals at risk of parenteral transmission. Many questions remain, most importantly the pathogenic role of the virus. It is unlikely that this virus has a major role in hepatic disease.

Flaviviridae↗
PubMed1998

African origin of human T-lymphotropic virus type 2 (HTLV-2) supported by a potential new HTLV-2d subtype in Congolese Bambuti Efe Pygmies.

We identified a potential new subtype within human T-cell lymphotropic virus type 2 (HTLV-2), HTLV-2d, present in members of an isolated Efe Bambuti Pygmy tribe. Two of 23 Efe Pygmies were HTLV-2 seropositive, with HTLV-2 Western blot and enzyme-linked immunosorbent assay reactivities. From one of them the entire genome of the HTLV-2 strain Efe2 could be amplified and sequenced. In all gene regions analyzed, this strain was the most divergent HTLV-2 strain, differing by 2.4% (tax/rex) to 10.7% (long terminal repeat) from both subtypes HTLV-2a and HTLV-2b, yet major functional elements are conserved. The similarity between the HTLV-2 Efe2 Gag and Env proteins and the corresponding HTLV-2a and -2b proteins is consistent with the observed serological reactivity. In the proximal pX region, one of the two alternative splice acceptor sites is abolished in HTLV-2 Efe2. Another interesting feature of this potential new subtype is that it has a Tax protein of 344 amino acids (aa), which is intermediate in length between the HTLV-2a Tax protein (331 aa) and the HTLV-2b and -2c Tax proteins (356 aa) and similar to the simian T-cell lymphotropic virus type 2 (STLV-2) PP1664 Tax protein. Together these two findings suggest a different phenotype for the HTLV-2 Efe2 strain. Phylogenetic analyses confirmed that the Pygmy Efe2 strain potentially belonged to a new and quite divergent subtype, HTLV-2d. When the STLV-2 bonobo viruses PP1664 and PanP were used as an outgroup, it was clear that the Pygmy HTLV-2 Efe2 strain had the longest independent evolution and that HTLV-2 evolution is consistent with an African origin.

Amino Acid Sequence↗
PubMed1998

Molecular analysis of GB virus C isolates in Belgian hemodialysis patients.

GB virus C (GBV-C) has been detected in Belgian hemodialysis patients. To study their genomic diversity and phylogenetic relationship, a 592 nucleotide fragment extending from the 5' non-coding region to part of the E1 gene of the GBV-C genome was amplified and sequenced from 12 Belgian hemodialysis patients in two different centers. Together with strains from different geographical origins, these sequences were analyzed phylogenetically using three different methods. A consistent tree topology was obtained with all methods. Three GBV-C genotypes were observed with two subtypes in type 2 and a questionable subtyping in type 1. Except for one isolate falling into type 1 cluster which mainly consists of African strains, all the other Belgian strains clustered within the type 2a branch. Two GBV-C isolates in two patients from the same hemodialysis center clustered together closely, suggesting a nosocomial transmission. In view of their long branch length, it seems unlikely that the other Belgian strains evolved recently from a common ancestor. Our results indicate that the major type circulating among Belgian hemodialysis patients seems to be 2a, which is usual for Europe and North America, but that the African type 1 also exists to a minor extent. Although patient to patient transmission of GBV-C in Belgian hemodialysis centers did occur, it may not account for the majority of infections.

Base Sequence↗
PubMed1997

Use of a generic polymerase chain reaction assay detecting human T-lymphotropic virus (HTLV) types I, II and divergent simian strains in the evaluation of individuals with indeterminate HTLV serology.

In countries with a low prevalence of human T-lymphotropic virus (HTLV) infection, indeterminate HTLV serologies are a major problem in blood bank screening because of the uncertainties about infection in these cases. The recent discovery of two new types of simian T-lymphotropic viruses (STLV), which give an HTLV-indeterminate serology, raises the question whether indeterminate serologies in humans may be linked to new types of HTLV. Starting from a Tax sequence alignment of all available primate T-cell lymphotropic virus strains (PTLV), including the two new types STLV-PH969 and STLV-PP1664, we developed generic and type-specific nested polymerase chain reactions (PCRs). The generic PCR proved to be highly sensitive and cross-reactive for all four types of PTLV, while the discriminatory PCRs had a high sensitivity and a specificity of 100%. There was no cross-reactivity with human immunodeficiency virus (HIV), ensuring correct interpretation of results from coinfected patients. Among the 77 serologically indeterminate samples tested, 6 were found to be HTLV-1 PCR positive and 1 was HTLV-II PCR positive. Sequencing of one of the HTLV-I PCR positives excluded PCR contamination, and revealed a divergent type of HTLV-I. The majority of the seroindeterminate samples (91%) were however HTLV-PCR negative, and no new types of HTLV were found. This new assay can identify otherwise undetected HTLV-I or HTLV-II infections and is a useful tool of screening for new types of HTLV among seroindeterminate samples.

Animals↗
PubMed1996

The three human T-lymphotropic virus type I subtypes arose from three geographically distinct simian reservoirs.

To investigate the origin of human T-lymphotropic virus I (HTLV-I), strains of diverse geographical origin were analysed. We sequenced the LTR and env genes of HTLV-I strains from Brazil, Central African Republic, Taiwan and Zaire, and the simian T-lymphotropic virus type I (STLV-I) strain PHSu1 from a baboon from the Sukhumi primate centre. We performed phylogenetic analyses using neighbour-joining, parsimony and maximum likelihood methods. Three separate HTLV-I clusters were identified interspersed between STLV-I clusters. The Brazilian and the Taiwanese strains were within the first well-supported cluster containing all cosmopolitan HTLV-I strains flanked by west African STLV-I strains. The HTLV-I strains from Central African Republic and Zaire fell into a central African cluster close to the chimpanzee STLV-I isolates. The third well-supported cluster included all Melanesian HTLV-I strains and had Indonesian STLV-I strains as closest neighbours. Therefore, currently known HTLV-I strains represent three HTLV-I subtypes that most probably have originated from three geographically distinct interspecies transmission events. The highly divergent PHSu1, isolated from Papio hamadryas, was closely related to PCY-991, isolated from Papio cynocephalus, both from the Sukhumi primate centre. Both clustered together with Asian wild-caught rhesus macaque STLV-I strains suggesting recent interspecies transmission of virus from rhesus macaques to colony-bred African baboons at the Sukhumi primate centre. In the rooted env trees obtained using the STLV strain PH969 as an outgroup, the Asian strains branched off before the African strains, implying an Asian origin for HTLV/STLV type I based on presently available strains.

Animals↗