Biomedical subjects

J J Gray

Publications and source records attributed to J J Gray.

At least 19 recordsLinked to original sources

PubMed1999

Molecular epidemiology of outbreaks of gastroenteritis associated with small round-structured viruses in East Anglia, United Kingdom, during the 1996-1997 season.

During the winter season from November 1996 to May 1997, 550 fecal specimens were submitted from 94 outbreaks of gastroenteritis occurring in East Anglia, United Kingdom. These specimens were tested for the presence of small round-structured viruses (SRSVs) by electron microscopy, reverse transcriptase PCR, or both methods. SRSVs were shown to be associated with 64 of 94 (68%) of these outbreaks, of which 16 (25%) outbreaks occurred at a single location (Southend) within the region. Twenty-four specimens from 13 of the 16 SRSV-positive outbreaks occurring in Southend were available for genomic analysis, in which divergence within the RNA polymerase region of the SRSV genome was investigated. A further 27 specimens from 17 other SRSV-associated outbreaks, occurring at different locations within East Anglia but at the same time as those at Southend, were also studied. Fifty of the total of 51 (98%) specimens studied were shown to belong to genogroup II, and within this genogroup, 49 of 50 (98%) specimens were shown to be Grimsby-like viruses, with only one Mexico-like strain. Furthermore, phylogenetic analysis of the Grimsby-like viruses indicated clusterings according to the geographical location of the outbreak. One specimen contained a virus belonging to genogroup I, and this had the greatest sequence identity (83%) with Southampton virus.

Base Sequence↗

PubMed1997

Mixed genogroup SRSV infections among a party of canoeists exposed to contaminated recreational water.

Samples of faeces collected from a party of canoeists involved in a gastroenteritis outbreak were examined by electron microscopy and RT-PCR for evidence of infection with SRSVs. A broadly reactive primer pair was used to detect SRSVs followed by application of genogroup-specific primers to SRSV-positive specimens. Exposure data were collected by means of a questionnaire. SRSVs were detected in 1/4 specimens examined by EM and 3/4 by RT-PCR. Genogrouping, and sequencing of PCR products revealed two distinct strains: a genogroup I strain, related to the Desert Shield virus, and a genogroup II strain, related to the Lordsdale virus to be associated with the outbreak. Exposure data indicated that capsising and eating food before getting changed were associated with an increased risk of gastroenteritis and was consistent with infection following the consumption of contaminated water. This study confirms the greater sensitivity of RT-PCR for the diagnosis of SRSV infections and its utility, when incorporating genogroup-specific primers, in establishing more complex epidemiological data.

Adolescent↗

PubMed1996

Hepatitis B virus surface mutations associated with infection after liver transplantation.

BACKGROUND/AIMS: Liver transplantation for chronic liver disease due to hepatitis B virus infection is associated with a high risk of graft infection, graft failure and death. Many centres restrict this procedure to those seronegative for HBV-DNA (by hybridisation assay) and use prophylactic polyclonal human hepatitis B specific immunoglobulin to prevent infection of the graft, despite the very high cost. METHODS: We describe three patients who underwent liver transplantation for chronic HBV-related disease in whom death was due to fibrosing cholestatic hepatitis following graft infection with hepatitis B virus, despite receiving hepatitis B specific immunoglobulin. Variation within the immunodominant a epitope of HBsAg was sought by analysis of hepatitis B virus sequences and the use of a point mutation assay, following amplification from serum by the polymerase chain reaction. RESULTS: Prior to transplantation, Cases 1 and 2 had mutations at nucleotide 1902 (codon 145), resulting in G-C substitutions, which persisted at a low level after transplantation. In Case 2 a second mutant type with a G-A substitution at nucleotide 1902, became the predominant viral type post transplant. Case 3 had exclusively wild type virus before and after transplantation. The emergence of mutant type virus in Case 2 may have occurred because of immune pressure exerted by high titre anti-HBs detectable for more than 7 months. Cases 1 and 3 received only brief courses of anti-HBs therapy. The mutant viral surface antigen was not detected by a monoclonal antibody-based assay, and therefore the choice of HBsAg assay for post-transplant monitoring of patients who receive liver grafts for hepatitis B virus disease is important. CONCLUSIONS: A search for mutations affecting the a determinant prior to liver transplantation for HBV-related liver disease may help to identify those at risk of failure of prophylaxis. Monoclonal antibodies specific to the codon 145-mutant surface antigen might prevent graft infection, but other mutations might then emerge.

Base Sequence↗

PubMed1996

Accuracy of serology for the diagnosis of Helicobacter pylori infection--a comparison of eight kits.

AIMS: To determine the accuracy of eight commercially available kits for the serological diagnosis of Helicobacter pylori infection, and hence whether a serology service could be introduced to reduce endoscopy workload. METHODS: Eighty four patients newly presenting to their general practitioners with dyspepsia were recruited. Gold standard diagnosis of H pylori infection was obtained both by a histological examination of gastroduodenal biopsy specimens and by the 14C-urea breath test (UBT). The performance of six quantitative and two qualitative enzyme linked immunosorbent assays for H pylori IgG, used according to the manufacturers' instructions, with serum samples obtained during the endoscopy visit, were compared. RESULTS: The study population had a median age of 45 years, and the prevalence of H pylori infection was 35%. With one exception, where the patient had received a course of anti-H pylori treatment between endoscopy and UBT, there was 100% concordance in the results of the two gold standard techniques. Discordant serology results were more common in patients aged > 50 years (42% of the total) than in younger patients (21%), and this was most noticeable in uninfected patients. The sensitivity of the kits was good (90-100%), but specificity was more variable (76-96%), and the rate of equivocal results was unacceptably high in some cases (0-12%). The overall accuracy of the kits ranged from 83 to 98%. Two kits in particular performed well (Pylori-Elisa II, Bio-Whitaker and Premier, Launch; qualitative) with 98% and 100% accuracy, respectively. CONCLUSIONS: In a symptomatic population with a prevalence of H pylori infection of 35%, particularly in patients aged < 50 years, some but not all serology kits may be used as a highly accurate and inexpensive alternative to the gold standard techniques.

Adult↗

PubMed1995

Avidity of EBV VCA-specific IgG antibodies: distinction between recent primary infection, past infection and reactivation.

A commercial Epstein-Barr virus (EBV) antivirus capsid antigen (VCA) IgG antibody ELISA and an 'in-house' EBV VCA IgG immunofluorescence antibody assay (IFA) were used to detect EBV VCA IgG antibodies in 100 serum samples collected from organ transplant recipients and immunocompetent individuals. The avidity of EBV VCA IgG antibodies was determined in the IFA and ELISA using the mild reducing agent 8 M urea to remove low avidity antibodies. The samples were collected from patients who had previously been identified with a primary EBV infection, a reactivation of latent infection or evidence of a past EBV infection by means of EBV-specific serology. Using the ELISA, the antibody avidity was low in samples collected from patients with recent EBV infection and high in samples collected from patients with a past infection or a reactivation. There was a statistically significant difference of means (P < 0.001) of percentage reduction in optical density values, measured in the presence of 8 M urea, obtained with samples collected from patients with recent infection compared with samples from patients with a past infection or a reactivation of latent infection.

Antibodies, Viral↗

PubMed1995

Serological reactivity against cyst and tachyzoite antigens of Toxoplasma gondii determined by FAST-ELISA.

AIMS: To obtain quantitative data on the human serological response to Toxoplasma gondii tachyzoite and bradyzoite antigens. METHODS: Serum samples from 30 patients who had positive antibody titres against T gondii and from 14 who were seronegative, together with sequential serum samples from four infected individuals, were screened by FAST-ELISA. RESULTS: Serum samples from the 30 seropositive patients showed high IgG and IgM titres against the T gondii tachyzoite antigen but very low responses to cyst antigen. This result was borne out in sequential serum samples from patients with toxoplasmosis. CONCLUSION: Antibody recognition of the cystic stage of T gondii is low, implying that either this stage is poorly immunogenic or that the antigen load is low.

Animals↗

PubMed1995

Internal quality assurance in a clinical virology laboratory. I. Internal quality assessment.

AIMS: In April 1991 an internal quality assessment scheme (IQAS) was introduced into the virology section of the Clinical Microbiology and Public Health Laboratory, Cambridge. The IQAS was established to identify recurring technical and procedural problems, to check the adequacy of current techniques, and to calculate the frequency of errors. METHODS: Between April 1991 and December 1993, 715 anonymous clinical serum samples were submitted to the laboratory to test 3245 individual procedures of diagnostic viral serology. RESULTS: A total of 485 (14.9%) procedural and 61 (1.9%) technical discrepancies were observed, the technical discrepancies mainly being recorded in complement fixation tests. Twenty two (0.7% of total procedures) of the technical discrepancies were diagnostically significant. CONCLUSIONS: Evaluation criteria developed with the introduction of IQAS to viral serology, and technical and procedural discrepancies are assessed. As yet, IQAS has not been introduced to other sections of the diagnostic virology laboratory (virus isolation, electron microscopy, immunofluorescence, and enzyme linked immunosorbent assays for viral and chlamydial antigens).

Humans↗

PubMed1995

Internal quality assurance in a clinical virology laboratory. II. Internal quality control.

AIMS: In April 1991 additional quality control procedures were introduced into the virology section of the Clinical Microbiology and Public Health Laboratory, Cambridge. Internal quality control (IQC) samples were gradually included in the serological assays performed in the laboratory and supplemented kit controls and standard sera. METHODS: From April 1991 to December 1993, 2421 IQC procedures were carried out with reference sera. RESULTS: The IQC samples were evaluated according to the Westgard rules. Violations were recorded in 60 of 1808 (3.3%) controls and were highest in the IQC samples of complement fixation tests (25/312 (8%) of controls submitted for complement fixation tests). CONCLUSIONS: The inclusion of IQC samples in the serological assays performed in the laboratory has highlighted batch to batch variation in commercial assays. The setting of acceptable limits for the IQC samples has increased confidence in the validity of assay results.

Complement Fixation Tests↗

PubMed1995

Development and validation of a new body-image assessment scale.

This investigation reports the development and validation of a new and improved body-image assessment tool, the Contour Drawing Rating Scale, consisting of nine male and nine female contour drawings. The drawings were designed with detailed features, are of precisely graduated sizes, and are easily split at the waist for accurate upper and lower body comparisons. Initial evidence of the scale's reliability and validity supports its use as a measure of body-size perception.

Adolescent↗

PubMed1994

Primary human herpesvirus-6 infection is frequently overlooked as a cause of febrile fits in young children.

Sera from 248 children aged 30-179 weeks were tested retrospectively for human herpesvirus-6 (HHV-6) IgG antibody avidity. Twenty-five children presented with febrile fits, in one case with a rash, exanthem subitum resulting from primary HHV-6 infection was diagnosed at the time, but in the others HHV-6 was not considered in the differential diagnosis even though two patients had a rash. In fact, five of the 25 patients experienced primary infection as shown by low avidity HHV-6 antibody. Although nine other of these patients were seronegative in the acute phase of the illness, and unfortunately convalescent sera were not available to confirm primary HHV-6 infection, seronegativity was clearly a risk factor for febrile fits (P = 0.03, odds ratio 3.14 for all children; P = 0.002, odds ratio 7.20 for children aged 70-179 weeks), and primary HHV-6 infection was a very likely diagnosis. The remaining 11 children had high avidity antibody, so HHV-6 was excluded as a cause of their febrile fits. HHV-6 may frequently be a cause of febrile fits, often without the typical rash of exanthem subitum, and this diagnosis is often overlooked by clinicians.

Antibodies, Viral↗

PubMed1994

Maturation of antibody avidity after primary human cytomegalovirus infection is delayed in immunosuppressed solid organ transplant patients.

An IgG antibody avidity assay which uses urea to modify a commercial enzyme-linked immunosorbent assay (ELISA) has been investigated for its ability to distinguish primary human cytomegalovirus (CMV) from recurrent or long-term infection. Twenty-four immunosuppressed solid organ transplant patients were studied. The avidity indices for IgG to CMV were low for 12 out of 13 patients with primary infection (mean 18%), high for all 11 patients with long-term infection (mean 85%), and the 1 patient with primary infection showing an intermediate avidity index (51%) was found to have acquired passively large amounts of CMV immunoglobulin, presumably of high avidity, during therapy. From the results, low and high avidity indices were defined as lying between 0-34% and 60-100%, respectively, and it was thus clear that the avidity assay can discriminate between primary and recurrent or long-term CMV infection. The avidity indices of eight of the immunosuppressed organ transplant patients with primary infection were followed in serial serum samples over time and IgG antibody to CMV was found to take at least a year to mature to high avidity in contrast to the 2-6 months expected for normal subjects. This finding provides evidence that immunosuppression has subtle, hitherto unsuspected, effects on humoral immunity to CMV in addition to the well-known depression of cell-mediated responses. It is concluded that this reliable avidity assay will be of importance in the diagnosis of CMV infection and in elucidating the pathogenesis of CMV-induced disease in organ transplant recipients.

Adult↗

PubMed1994

Transmission of hepatitis C virus by organ transplantation in the United Kingdom.

This study employed a second-generation anti-HCV ELISA, and a second-generation recombinant immunoblot assay and hepatitis C virus RNA detection by polymerase chain reaction to investigate the anti-HCV prevalence in 554 British organ donors and the transmission of hepatitis C virus to heart, liver and kidney recipients between 1984 and 1991. Serum samples from six (1.08%) donors were reactive in the second-generation anti-HCV ELISA and four (67%) of these gave positive or indeterminate results in the recombinant immunoblot assay-2. Of the 15 recipients of these organs from hepatitis C virus-confirmed positive/indeterminate donors, 14 (93%) acquired hepatitis C virus infection and seven (47%) had evidence of hepatitis C virus-related liver disease after transplantation and no evidence of blood transfusion-related transmission. Only six of the 15 (40%) recipients had detectable anti-HCV after transplantation, while 12 of 14 (86%) patients tested had hepatitis C virus RNA in their serum detectable by "nested" polymerase chain reaction. These data indicate a very high rate of transmission with a major risk of the development of liver disease. We believe our study supports the testing of all British organ donors for anti-HCV and that organs from anti-HCV-positive patients should not be transplanted unless the recipient has life-threatening disease and there is a donor shortage, when their use may be justified. Since there are time constraints on organ donor testing, which may frequently be done on call during unsocial hours, we would recommend second-generation ELISA as the current screening test of choice.(ABSTRACT TRUNCATED AT 250 WORDS)

Enzyme-Linked Immunosorbent Assay↗

PubMed1994

Detection of immunoglobulin M (IgM), IgA, and IgG Norwalk virus-specific antibodies by indirect enzyme-linked immunosorbent assay with baculovirus-expressed Norwalk virus capsid antigen in adult volunteers challenged with Norwalk virus.

Pre- and postexposure sera collected from 17 adult volunteers challenged with Norwalk virus as described previously (D. Y. Graham, X. Jiang, T. Tanaka, A. Opekun, P. Madore, and M. K. Estes, J. Infect. Dis. 170:34-43, 1994) were examined for Norwalk virus-specific immunoglobulin M (IgM), IgA, and IgG by indirect enzyme-linked immunosorbent assays with recombinant Norwalk virus antigen bound to the solid phase. Sixteen of the 17 volunteers had evidence of past infection, all presenting with preexisting IgG antibody of high avidity; only one volunteer had no evidence of previous infection. Virus infection was detected in 14 of the 16 volunteers with evidence of past infection, and 9 of the infected volunteers had symptomatic illness. A significant rise in both virus-specific IgA and IgG titers was detected after challenge in all of the volunteers who became ill. Five of the asymptomatic volunteers who were infected had rising titers of virus-specific IgG, but only two of the five had a concomitant rise in their virus-specific IgA antibody titers. Antibody rises were detectable in eight of nine ill volunteers 8 to 11 days after challenge but in the asymptomatic volunteers only after more than 15 days had elapsed. Virus-specific IgM was detected after challenge in all 14 infected volunteers. Between symptomatic and asymptomatic volunteers there were no significant differences in titers of virus-specific IgG and IgA in serum before challenge; however, there were significantly higher titers in symptomatic volunteers between 8 and > 90 days after challenge for virus-specific IgG and 8 and 24 days after challenge for virus-specific IgA.

Adult↗

PubMed1993

Disordered eating attitudes and behaviors, psychological adjustment, and ethnic identity: a comparison of black and white female college students.

The low prevalence of restrictive eating disorders among black women has been attributed primarily to cultural differences in the definition of beauty. Utilizing self-report measures, this study examined differences in the nature of disordered eating behaviors for black and for white female college students. Analyses of covariance and correlational tests revealed that white females demonstrated significantly greater disordered eating attitudes and behaviors than black females. Additionally, the data indicated that although disordered eating behaviors and attitudes are related to actual weight problems for black females, this is not the case for white females. Furthermore, this study is the first to provide evidence that restrictive eating disorders among black women are related to the degree to which they assimilate to mainstream culture. Finally disordered eating behaviors and attitudes were related to depression, anxiety, and low self-esteem in both groups.

Acculturation↗

PubMed1993

Avidity of IgG antibodies to human herpesvirus-6 distinguishes primary from recurrent infection in organ transplant recipients and excludes cross-reactivity with other herpesviruses.

A newly developed IgG antibody avidity test for human herpesvirus-6 (HHV-6) was used in a study of primary and recurrent HHV-6 antibody responses in immunocompromised solid organ graft recipients. In a primary HHV-6 infection low avidity antibody was detected which matured to high avidity within 5 months whereas, in contrast, high avidity antibody was found in three recurrent infections thus showing the ability of the test to discriminate between primary and recurrent infection in immunosuppressed patients. Six HHV-6 seropositive transplant patients who experienced a subsequent primary human cytomegalovirus (CMV) infection had high avidity concurrent HHV-6 antibody rises, thus excluding a cross-reaction from the low avidity antibodies generated in the primary CMV response and providing evidence of recurrent HHV-6 infection. Four further HHV-6 seropositive patients with proven primary Epstein-Barr virus (EBV) infection were also studied; in each of these cases high avidity HHV-6 antibody rises were seen likewise suggesting recurrent HHV-6 infection. The test is therefore of value in the investigation of herpesvirus infections in transplant patients.

Adolescent↗

PubMed1993

IgG antibodies to human herpesvirus-6 in young children: changes in avidity of antibody correlate with time after infection.

Sera from 321 children aged 0-179 weeks and 196 adult blood donors were examined for IgG antibodies to human herpesvirus-6 (HHV-6) using an indirect immunofluorescence test. After birth, antibody prevalence declined to a minimum between 20 and 29 weeks. Thereafter the percentage of individuals with antibody increased up to the age of 60-69 weeks after which the prevalence of antibody in the children remained stable at about 88%; in contrast, the seroprevalence in blood donors was 98%, indicating that some individuals remain susceptible to infection after early childhood but that virtually all are infected by the time they reach adulthood. The HHV-6 antibody titre increased steadily over the first 70 weeks of life and then remained stable up to 179 weeks old at a level significantly higher than that of the adults. Two hundred and eighteen of the 321 sera whose HHV-6 antibody titres were 40 or greater were tested for antibody avidity using a modification of the immunofluorescence test whereby low avidity antibody was eluted with urea. The results show that the age distribution of low avidity antibody closely parallels the known distribution of exanthem subitum and, moreover, that the mean antibody avidity increased with time after primary infection. The method was further validated because well-characterised convalescent sera taken from seven children within 3 weeks of exanthem subitum all contained low avidity antibodies. The data presented in this study indicate that low avidity IgG to HHV-6 may be detected after primary infection and that this should prove useful in diagnosis and for seroepidemiological surveys.

Adult↗

PubMed1993

Detection of human parvovirus B19-specific IgM and IgG antibodies using a recombinant viral VP1 antigen expressed in insect cells and estimation of time of infection by testing for antibody avidity.

Sera from patients with symptoms of recent human parvovirus B19 (B19) infection were tested for B19-specific IgM in an immunofluorescence assay (IFA) using insect cells expressing B19 recombinant VP1 coat protein as an antigen. A highly significant correlation (P < 0.001) was found between titres obtained in the IgM IFA and the units obtained in an IgM antibody-capture RIA using plasma derived native B19 antigen. An IgG IFA using the recombinant antigen was performed on 57 sera and the antibody avidity determined. There was a highly significant correlation (P < 0.001) between the relative amounts of low avidity B19-specific IgG antibodies and time after onset of illness. This finding allows the detection of IgG to be used for diagnosing acute infection.

Animals↗

PubMed1993

A case of transfusion-acquired hepatitis C.

The Blood Transfusion Service introduced screening for Hepatitis C antibody (HCV) in September 1991. This is done by second generation enzyme linked immunosorbent assay (ELISA) tests. We present a case of post-transfusion hepatitis C hepatitis in a patient with myeloma. Infection was acquired before screening was introduced. Both the patient and the infected blood donor were diagnosed using ELISA assays and the polymerase chain reaction (PCR). In this way we prevented the blood donor from spreading the virus via subsequent blood donations. There were some interesting discrepancies in the HCV assays. Blood samples, when tested by different methods, gave both positive and negative results. The results also varied according to when the blood samples to be tested were taken. The case illustrates the importance of confirming positive results and that no single laboratory test is entirely satisfactory in diagnosing HCV infection.

Aged↗