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Biomedical subjects

J K Ball

Publications and source records attributed to J K Ball.

At least 19 recordsLinked to original sources
PubMed2007

Severe fibrosis in hepatitis C virus-infected patients is associated with increased activity of the mannan-binding lectin (MBL)/MBL-associated serine protease 1 (MASP-1) complex.

Mannan-binding lectin (MBL) binds microorganisms via interactions with glycans on the target surface. Bound MBL subsequently activates MBL-associated serine protease proenzymes (MASPs). A role for MBL in hepatitis C virus (HCV) infection had been indicated by previous studies examining MBL levels and polymorphisms in relation to disease progression and response to treatment. We undertook this study to investigate a possible relationship between disease progression and functional MBL/MASP-1 complex activity. A functional assay for MBL/MASP-1 complex activity was employed to examine serum samples from patients with chronic HCV infection, non-HCV liver disease and healthy controls. Intrapatient consistency of MBL/MASP-1 complex activity levels was assessed in sequential samples from a subgroup of patients. Median values of MBL/MASP-1 complex activity were higher in sera from patients with liver disease compared with healthy controls. MBL/MASP-1 complex activity levels correlate with severity of fibrosis after adjusting for confounding factors (P = 0.003). MBL/MASP-1 complex activity was associated more significantly with fibrosis than was MBL concentration. The potential role of MBL/MASP-1 complex activity in disease progression is worthy of further study to investigate possible mechanistic links.

Adolescent↗
PubMed2001

Direct ex vivo comparison of the breadth and specificity of the T cells in the liver and peripheral blood of patients with chronic HCV infection.

The role of intrahepatic lymphocytes in the control of hepatitis C virus (HCV) infection and the pathology associated with it is not understood; most studies of the immunology of this infection use peripheral blood lymphocyte populations. To address this further, we examined in detail the IHL from HCV-infected patients and controls, focusing on the antigen-specific CD8(+) T lymphocyte component. Individual T cells from needle liver biopsies and peripheral blood were isolated from patients with chronic HCV infection and examined directly ex vivo. We used RT-PCR spectratyping to compare the breadth of the T cell receptor usage in the liver in comparison with the peripheral blood, and applied MHC class I tetramer technology to investigate the numbers of HCV-specific CD8(+) cells in the two compartments. T cell receptor usage in the liver of HCV-infected patients was broad, comparable with that in the peripheral blood of the same patients. A much higher proportion of liver CD8(+) cells expressed receptors specific for HCV antigens compared with paired peripheral blood CD8(+) cells. A greater proportion of the liver tetramer-positive cells expressed the activation marker CD69, compared with those in the periphery or other CD8(+) cells in the liver. In the course of chronic HCV infection, HCV-specific CD8 cells, which have been recently activated, appear to accumulate specifically in the livers of infected patients but are present in much lower numbers in the peripheral circulation. Further studies are needed to determine the function of these cells and their role in protection and immunopathology.

CD8-Positive T-Lymphocytes↗
PubMed2001

Development of a strand-specific RT-PCR based assay to detect the replicative form of hepatitis C virus RNA.

The recent development of tagged RT-PCR and rTth RT-PCR has greatly improved strand-specific detection of hepatitis C virus (HCV) RNA but these assays are still prone to some false detection of the incorrect strand of RNA. In this study we aimed to address additional factors which contribute towards false detection of HCV RNA. Firstly the benefits of both tagged primers and the thermostable reverse transcriptase rTth during cDNA synthesis were combined and it was found that strand specificity was greatly improved without compromising sensitivity. The reliability of the assay was then optimised by addressing the following issues: control synthetic transcripts should be free of contaminating plasmid DNA, residual RT activity should be minimised in the presence of PCR primers and cDNA should be free of unincorporated tagged RT primer prior to PCR amplification. The alterations made to the assay eliminated completely false detection of the incorrect strand of RNA in the control assay whilst the correct strand was consistently detected at a cDNA dilution of 10(-3)-10(-4). Negative strand was not detected in RNA isolated from serum but was detected, at a ten-fold lower level than positive strand, in RNA isolated from liver tissue.

DNA Repair Enzymes↗
PubMed2000

A polymerase chain reaction method for the amplification of full-length envelope genes of HIV-1 from DNA samples containing single molecules of HIV-1 provirus.

Polymerase chain reaction (PCR) amplification of full-length envelope genes from the human immunodeficiency virus type 1 (HIV-1) directly from uncultured clinical samples is difficult. This paper describes a comparative assessment of the performance of three thermostable polymerases in an HIV-1 full-length envelope gene PCR. The PCR method utilising Expand HiFi polymerase was successful when using DNA samples extracted from a variety of sources including blood, semen and various tissues. This method generated high and specific yields of product from samples containing as little as one copy of HIV-1 proviral DNA. The resulting PCR products were suitable for a variety of downstream analytical methods including DNA sequence analysis.

Base Sequence↗
PubMed1999

Cloning, tissue distribution, subcellular localization and overexpression of murine histidine-rich Ca2+ binding protein.

The histidine-rich Ca2+ binding protein (HRC) resides in the sarcoplasmic reticulum of muscle and binds Ca2+. Since Ca2+ concentrations can regulate gene expression via calcineurin, the mouse homologue of HRC (mHRC) was isolated and characterized. mHRC was detected in muscle progenitor cells, in primary clonal thymic tumors and a tumor cell line, suggesting a broader role for mHRC than in Ca2+ storage during muscle contraction. mHRC was present in the perinuclear region of myoblasts. To examine if it can regulate gene expression, mHRC was overexpressed in cells differentiating into cardiac and skeletal muscle. mHRC had no effect on cardiogenesis or myogenesis. Therefore, if mHRC plays a role in the regulation of gene expression during cellular differentiation, it does not appear to be either rate-limiting or inhibitory.

Amino Acid Sequence↗
PubMed1999

HIV-1 in semen: determination of proviral and viral titres compared to blood, and quantification of semen leukocyte populations.

This study was carried out to determine the relationship between proviral DNA and viral RNA titres in semen compared with blood. In addition, the association between semen leukocyte counts with detection frequency and absolute levels of human immunodeficiency virus type 1 (HIV-1) nucleic acids was also assessed. Paired samples of blood and semen were collected from a cohort of individuals with different blood CD4 cell counts, and whose anti-HIV therapy had not changed in the preceding 3 months. The cell-associated proviral DNA titres and cell-free plasma viral RNA titres were determined using nested primer polymerase chain reaction and NASBAtrade mark, respectively. In addition, leukocyte counts were determined by immunocytochemical and cytochemical staining of a subset of semen samples. HIV-1 proviral DNA was detected in 100% and 47%, and viral RNA was detected in 76% and 63%, of blood and semen samples tested, respectively. HIV-1 proviral DNA and viral RNA titres in blood were higher than in corresponding semen samples, although the difference observed in viral RNA titres was not statistically significant. Proviral DNA and viral RNA titres were correlated between the two body fluids, and within the semen, although some individuals had disparate semen and blood titres or detection rates, indicating genital tract compartmentalisation. In addition, detection of HIV-1 proviral DNA, but not of HIV RNA, in semen was associated with elevated semen leukocyte counts, although this latter finding requires verification in future studies of larger numbers of patients.

CD4 Lymphocyte Count↗
PubMed1999

TT virus infection in patients with hepatitis C: frequency, persistence, and sequence heterogeneity.

TT virus (TTV) was recently identified in the serum of a patient with hepatitis. The role of TTV in liver disease has not been established. Three polymerase chain reaction (PCR) protocols were used to detect TTV DNA in sera of persons infected with hepatitis C virus (HCV) and in blood donors. Sera from 11.5% of HCV-infected patients and 7.7% of blood donors were positive by protocols 1 or 2. In contrast, 48.7% and 57.7% of sera, respectively, were positive when tested by protocol 3. There was no difference in the severity of hepatitis in persons coinfected with TTV and HCV when compared with those infected with HCV alone, regardless of which TTV PCR protocol was used. TTV DNA persisted in serum samples taken up to 6 years apart in individual patients. Sequence analysis indicated that most viral sequences were distinct between patients, and there was evidence of genetic heterogeneity and viral evolution within individuals.

Adolescent↗
PubMed1999

TT virus sequence heterogeneity in vivo: evidence for co-infection with multiple genetic types.

TT virus (TTV) is a newly described DNA virus of humans that exhibits an unusually high degree of genetic heterogeneity. We have performed extensive analysis of the TTV populations present in samples, taken over a period of 2 to 6 years, from three individuals with persistent TTV infection. TTV DNA titres estimated for sequential samples were found to be quite stable over the entire study period in two patients, but fluctuated considerably in the third. DNA sequence analysis revealed different genetic diversity among TTV populations from samples from the three patients. In one case, absolute sequence homogeneity was observed among samples over a 3 year period. In a second, a limited amount of heterogeneity was found, including one sequence exhibiting G-->A hypermutation. TTV DNA sequences from the third patient exhibited quite remarkable genetic heterogeneity: evidence was found of seven distinct infecting viruses, representing four of the six TTV genotypes that have been described. In addition, minor variants of three of these seven sequences were observed. The heterogeneity of the viral population in this individual declined steadily over a 6 year period. This patient infected with a genetically diverse TTV population had the highest viral DNA titre.

Amino Acid Sequence↗
PubMed1999

Poor reduction of HIV-1 RNA titres in nucleoside reverse transcriptase inhibitor experienced patients treated with indinavir combination therapy.

OBJECTIVES: The long term effectiveness of combination therapy at reducing viral loads in seminal fluid and blood plasma obtained from HIV-1 infected men who had undergone previous antiretroviral therapy was assessed. METHODS: Samples of semen and blood were obtained from a cohort of 12 nucleoside reverse transcriptase inhibitor experienced men before and during 25-68 weeks of combination therapy, which included the protease inhibitor indinavir. HIV-1 RNA titres present in the cell free blood and seminal plasma samples were determined using the nucleic acid sequence based amplification (NASBA)/Nuclisens assay system. RESULTS: Viral RNA was detected in 9/12 and 7/12 baseline blood plasma and seminal plasma samples, with median viral titres of 10(4.81) and 10(4.56) per ml, respectively. By the end of the study period the detection rates of HIV RNA in the blood and seminal plasma samples were 5/12 and 2/12, respectively, with the median viral titres below the assay cut off level for both sample types. Of the nine patients who had detectable viral RNA in the baseline sample, only three cleared virus from both compartments by the end of the study. CONCLUSIONS: These data show that stable reduction of blood and seminal fluid viral titres is not achievable in a significant proportion of nucleoside reverse transcriptase inhibitor experienced men.

Drug Therapy, Combination↗
PubMed1998

GBV-C/HGV coinfection in HIV-1-positive men: frequent detection of viral RNA in blood plasma but absence from seminal fluid plasma.

Sequential paired samples of blood and seminal fluid were obtained from a cohort of 54 HIV-1-infected homosexual males. The prevalence of GBV-C/HGV RNA in the cell-free fractions of some of these patients was determined using reverse-transcription polymerase chain reaction (RT-PCR). To assess the effects of HIV-1 and HCV infection upon GBV-C/HGV RNA status, blood CD4 cell counts, HCV RNA status, and HIV-1 proviral DNA and viral RNA titres were also determined. GBV-C/HGV RNA was detected in 8/30 (27%) of the blood plasma samples obtained at the start of the study, and was present at a frequency of 14/64 (22%) in all the blood plasma samples tested. By contrast, GBV-C/HGV RNA was not detected in the 26 seminal fluid samples obtained at the start of the study, including 8 samples obtained from patients for which GBV-C/HGV RNA was detected in the corresponding blood sample. Of the samples tested for the presence of both GBV-C/HGV and HCV RNA, there was no evidence of coinfection. Although GBV-C/HGV RNA detection rates were significantly higher in individuals with blood CD4 cell counts greater than 200 cells per microlitre, there were no significant differences in the median blood CD4 cell counts or HIV-1 proviral DNA or viral RNA titres observed between the GBV-C/HGV-positive and -negative individuals. The failure to detect GBV-C/HGV RNA in seminal fluid samples obtained from this cohort would suggest that further studies need to be carried out to determine the roles of sexual transmission and of seminal fluid in GBV-C/HGV infection.

CD4 Lymphocyte Count↗
PubMed1998

Dendritic cells cultured from mononuclear cells and CD34 cells in myeloma do not harbour human herpesvirus 8.

Dendritic cells (DC) are antigen-presenting cells with the potential to be a powerful adjuvant in the immunotherapy of haematological malignancy, including myeloma. Recently, human herpesvirus 8 (HHV-8) infection of dendritic cells in the long-term bone marrow stromal cultures of patients with myeloma has been reported. This finding is of great potential importance regarding oncogenesis in myeloma in addition to having significant implications for the use of DC in the immunotherapy of this disease. Therefore DC generated from mobilized blood mononuclear cells (MO-DC) and purified CD34+ cells (CD34-DC) of myeloma patients were examined for the presence of HHV-8 using a sensitive PCR technique. HHV-8 was not demonstrated in MO-DC or CD34-DC and we conclude that these cells remain a suitable vehicle for investigation in the immunotherapy of myeloma.

Antigens, CD34↗
PubMed1997

Semen characteristics in HIV-1 positive men and the effect of semen washing.

We have undertaken an analysis of semen from HIV infected men with regard to sperm counts and motility, non-spermatozoal cells, and viral nucleic acid. Regression analysis showed that sperm concentration and motility were positively associated with blood CD4 cell count. By contrast, non-spermatozoal cell concentration (round cells) was inversely related to CD4 count. Extracellular HIV RNA was detected in the majority of semen samples and proviral DNA in a minority. Percoll gradient washing of 12 semen samples yielded six samples containing adequate sperm concentration for analysis. This washing procedure reduced prewash extracellular RNA to below detectable limits in all cases; proviral DNA present in two of the six prewash samples was also reduced to below detectable limits after washing. We conclude that semen washing before artificial insemination may reduce the risk of HIV transmission from an infected man to an uninfected woman. However, further evidence from prospective analyses of such an approach is required.

CD4 Lymphocyte Count↗
PubMed1996

Treatment differences between blacks and whites with colorectal cancer.

OBJECTIVES: The authors examine interracial variations in treatment for over 20,000 patients hospitalized with colorectal cancer in a national sample of hospitals. METHODS: To reduce clinical heterogeneity that could explain differences in treatment, hospitalizations were classified into relatively homogeneous subgroups based on diagnoses indicating primary colorectal tumor, oncologic sequelae, and metastasis. Procedures were classified into clinically relevant treatment types. Multivariate techniques controlled for differences in patient demographics, insurance status, other clinical factors, and provider characteristics. RESULTS: Blacks were more likely than whites to be hospitalized with oncologic sequelae, diagnoses indicating advanced disease, which may capture the effects of unmanaged or poorly managed cancer. Inpatient mortality was equivalent only for the most severely ill. Otherwise, the odds of inpatient mortality were 59% to 98% higher for blacks than whites. Treatment, in terms of procedure type, was equivalent only for the sickest patients. Among the less severely ill, blacks were less likely than whites to receive major therapeutic procedures. CONCLUSIONS: Multiple findings suggest that blacks with colorectal cancer were hospitalized with more severe conditions and treated less aggressively than whites. In an era of health-care reform, such differences, which are net of insurance effects, may require more than universal insurance coverage to be overcome.

Adolescent↗
PubMed1996

Concurrent evolution of regions of the envelope and polymerase genes of human immunodeficiency virus type 1 during zidovudine (AZT) therapy.

Nucleotide sequences of regions of the envelope (env) and polymerase (pol) genes of human immunodeficiency virus type 1 (HIV-1) proviral DNA were obtained from sequential blood and autopsy samples from an AIDS patient who had been treated with zidovudine for 9 months. Phylogenetic analyses showed that a reduction in genetic heterogeneity of the env regions of viruses present in the proviral blood population occurred during therapy, and this coincided with an increased pol gene heterogeneity. Differences were observed in different organs obtained post mortem for both the env and pol coding regions. The cardiac blood proviral population consisted mainly of variants which possessed sequences containing mutations at position 215 of the pol gene, associated with drug resistance. By contrast, the brain population consisted entirely of zidovudine sensitive genotypes, and this organ also harboured variants with genetically distinct env sequences. The lymph tissues obtained after death held more diverse proviral env and pol populations, containing both zidovudine sensitive and resistant genotypes.

Amino Acid Sequence↗
PubMed1994

Genomic variation of human immunodeficiency virus type 1 (HIV-1): molecular analyses of HIV-1 in sequential blood samples and various organs obtained at autopsy.

Length polymorphisms and partial nucleotide sequences were determined for the hypervariable regions, V1 to V5, of the human immunodeficiency virus type 1 (HIV-1) env gene obtained from proviral DNA of sequential peripheral blood samples, from viral RNA in plasma, and from proviral DNA obtained from different organs of individuals at autopsy. The lengths of several env regions of HIV-1 proviral DNA differed markedly when obtained from different organs of an individual. Nucleotide sequences of the hypervariable V3 region of HIV-1 obtained from different organs of one patient demonstrated distinct viral variants. Most proviral DNA sequences found in organs were also present in viral RNA obtained from plasma. The majority of HIV-1 V3 variants present in the lymph tissue could be found in the plasma viral population obtained at autopsy and in the sequential blood samples obtained before death, but were absent from the cardiac blood provirus population obtained at autopsy. However, sequence variants found in the brain proviral DNA were not detected in either plasma or the sequential blood samples. Sequence differences were observed at the apex of the V3 loop between HIV-1 variants present in sequential blood samples and in blood lymphocytes and nervous tissue, lymph tissue and plasma obtained post-mortem. The potential effect of lymph tissue on the long-term persistence of different viral variants is discussed. Virus obtained from the two sequential blood samples produced syncytia in primary cultures and was easily transmitted to the continuous JM cell line. Consensus (majority) V3 loop sequences determined for the adapted viruses demonstrated that some, but not all, sequences were represented within the in vivo viral population.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Black/white differences in colorectal tumor location in a national sample of hospitals.

This article describes a retrospective study that compared the distribution of colorectal tumors among black and white discharges. A total of 188,109 discharges with colorectal cancer were selected from the Hospital Cost and Utilization Project, a national sample of hospitals with 34 million patient discharges from 1980 to 1987. Black/white differences were small for right, left, and rectal tumors; however, black discharges had a higher percentage of colorectal tumors with sites unspecified. From 1980 to 1987, 295 per 1000 discharges of blacks had an unspecified tumor location, compared with 229 per 1000 discharges of whites (a 29% difference). Black discharges had a higher proportion of unspecified tumors than whites regardless of cancer severity, discharge status, procedure type, age, sex, expected third-party payer, and year. Black/white differences were maintained across hospital characteristics (region, rural/urban location, teaching status, bed size, and ownership). Differences in specification of tumor site may be an indicator of poor continuity of care, poor access, or other quality-related measures.

Aged↗
PubMed1993

Detection of HIV-1 by digoxigenin-labelled PCR and microtitre plate solution hybridisation assay and prevention of PCR carry-over by uracil-N-glycosylase.

An extremely sensitive and convenient microtiter plate solution hybridisation assay for the detection of HIV-1 PCR products was developed. The PCR product is labelled by direct incorporation of digoxigenin-dUTP and after denaturation is captured by a microtitre plate coated with a streptavidin-linked biotinylated probe. The PCR/probe hybrids are reacted with an alkaline phosphate conjugated anti-digoxigenin antibody and detected using an alkaline phosphatase enzyme amplification system. The use of uracil-N-glycosylase and dUTP instead of dTTP in the PCR is used to effectively control carry-over from previous PCR products. The assay can detect single HIV-1 DNA molecules in a background DNA of 0.75 microgram.

Base Sequence↗