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Biomedical subjects

A M van Loon

Publications and source records attributed to A M van Loon.

At least 91 records · Page 5Linked to original sources
PubMed1989

Detection of cytomegalovirus DNA in short term cultures.

Detection of human cytomegalovirus (CMV) by in situ DNA hybridisation six days after incubation of human diploid fibroblasts (ISDH-6) was evaluated prospectively in 205 urine samples, obtained from 57 kidney transplant and 17 bone marrow transplant recipients. The results were compared to those of conventional virus isolation (CVI) and the detection of CMV early antigens after one day of cultivation (EA-1). Of 42 samples positive for CMV by at least one of these methods, 40 (95%) were detected with ISDH-6. Thirty-five (83%) and 34 (81%) positive samples were found with CVI and EA-1, respectively. These data indicate that ISDH-6 is a sensitive method for detection of CMV. It can be used as a rapid and sensitive alternative to CVI in combination with EA-1.

Antigens, Viral↗
PubMed1989

Prevalence of HIV-1 antibody among groups of patients and healthy subjects from a rural and urban population in the Mwanza region, Tanzania.

In April 1987, antibody to HIV-1 was determined in sera from 764 subjects from the Mwanza region in the north of Tanzania. Patients with a clinical suspicion of AIDS were HIV-1 antibody-positive in 65.4% (34 out of 52) and patients admitted for pulmonary tuberculosis in 25% (9 out of 36). In patients attending general outpatient departments (OPD), HIV antibody was found in 12.5% of 48 patients with a history of sexually transmitted disease (STD) and in 10.6% of 141 patients without such a history. In healthy subjects, HIV-1 antibody was present in 6% of 332 pregnant women and in 4.5% of 155 blood donors. Of the blood donors, pregnant women and OPD patients without a history of STD (628 subjects in all), 465 belonged to the rural population of the region and the majority were peasants. In this subgroup, the HIV-1 antibody prevalence was 4.8% in blood donors, 4.9% in pregnant women and 10.3% in OPD patients. This indicates a spread of HIV-1 among the population in this part of Tanzania. Further studies are needed to determine what proportion of the population is affected.

Adolescent↗
PubMed1989

Diagnosis of herpes simplex virus encephalitis by detection of virus-specific immunoglobulins A and G in serum and cerebrospinal fluid by using an antibody-capture enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay was evaluated for detection of intrathecal synthesis of immunoglobulin G (IgG) and IgA antibodies to herpes simplex virus (HSV) in patients with HSV encephalitis (HSVE). Since the antibody-capture principle was used and the assay was carried out at the saturation level of the anti-IgG- or anti-IgA-coated solid phase, correction for blood-brain barrier leakage was not needed. A total of 34 pairs of serum and cerebrospinal fluid specimens obtained from 20 patients with HSVE were examined. Intrathecal synthesis of HSV IgG and IgA was detected from day 7 after the onset of illness in patients with HSVE. Specimens from all 19 patients from whom paired serum and cerebrospinal fluid specimens were obtained at more than 10 days after the onset of illness were positive. Intrathecal synthesis of HSV IgG and IgA was not detected in patients with HSVE before day 7 of illness or in any of the 16 control patients with other causes of (meningo)encephalitis. Use of the antibody-capture enzyme-linked immunosorbent assay for HSV IgG and IgA allows the rapid diagnosis of HSVE during the second week of illness.

Antibodies, Viral↗
PubMed1989

Antiperinuclear factor, a rheumatoid arthritis specific autoantibody: its relation to Epstein-Barr virus.

We studied the prevalence of antiperinuclear factor (APF), an antibody frequently (50-80%) present in sera of patients with rheumatoid arthritis (RA), in different groups of patients. Sera from 123 patients with RA and 28 patients with recent Epstein-Barr virus (EBV) infection showed APF in 63 and 51% of the patients, respectively. These frequencies were significantly increased (p0.001) when compared with 123 healthy blood donors (12%) and in 58 patients with herpes virus infections other than EBV (18%). Relations with other EBV elicited antibodies in RA and the relevance of EBV in RA are discussed. Our data suggest that EBV might be the immunogen for APF, an antibody, until now considered to be an autoantibody.

Adolescent↗
PubMed1988

The prevalence of serological markers, hepatitis B virus DNA and elevated serum amino transferase values in institutionalized mentally handicapped males and females: an epidemiological study of HBV infection in residents with Down's syndrome or other forms of mental deficiency.

Conventional HBV serological markers, as well as serum alanine amino transferase and hepatitis B virus DNA (HBV DNA) were studied in a population of 667 institutionalized mentally handicapped males and females and in 676 staff members. The role of Down's syndrome (DS), sex and age-related factors with respect to the prevalence of these markers was analyzed. A young age at admission was found as one of the important factors in the development of the chronic HBsAg carrier state in females. The well-known higher prevalence of HBsAg carriership in DS patients appeared to be restricted to males. Markers indicative of viral replication, HBeAg and HBV DNA, were also more prevalent in male than in female DS residents, or OMR residents. These findings indicate that the phase of active viral replication is prolonged in male HBsAg carriers with DS. However, only 66.7 per cent of HBV DNA-positive and 26.2 per cent of HBsAg-positive residents had abnormal serum alanine aminotransferase (ALT) values. In addition, more than 50 per cent of residents with elevated serum alanine amino transferase values were negative for HBV serological markers. We conclude that male DS residents are the main source of HBV infection in institutions for the mentally handicapped and that determination of ALT values is not very useful in identifying those HBsAg carriers capable of transmission the infection.

Age Factors↗
PubMed1988

Hepatitis B virus infection in an institution for the mentally retarded.

A cross-sectional survey on the prevalence of hepatitis B serologic markers and hepatitis B virus DNA was performed in a population of 493 mentally handicapped males. Special interest was focused on age-related variables such as age at entry into the institution and on duration of residency. Furthermore, the differences with regard to the prevalence of hepatitis B markers found in Down's syndrome residents and other mentally retarded persons were analyzed. In a longitudinal study, the impact of the presence of hepatitis B virus DNA in serum was studied. Overall, 62.1 per cent of residents had serologic evidence of infection with hepatitis B virus, while 16.7 per cent of those residents with markers of infection were positive for hepatitis B surface antigen (HBsAg). Hepatitis B virus DNA was found in 24 per cent of HBsAg carriers (all positive for hepatitis B e antigen (HBeAg). In residents whose age at entry was less than 15 years, those with Down's syndrome were more often carriers of HBsAg than other mentally retarded residents. In addition, Down's syndrome residents more often had serum hepatitis B virus DNA compared with residents with other forms of mental retardation. A young age at entry was recognized as an important factor with regard to the prevalence of hepatitis B markers. From the longitudinal studies, it appeared that loss of hepatitis B virus DNA from serum indicated imminent loss of HBeAg and normalization of alanine aminotransferase values. Knowledge of the hepatitis B virus DNA status of HBsAg carriers in these institutions may therefore provide a valuable tool in attempts to reduce the transmission of this infection.

Adolescent↗
PubMed1988

Immunological detection of cytomegalovirus early antigen on monolayers inoculated with urine specimens by centrifugation and cultured for 6 days as alternative to conventional virus isolation.

Detection methods for human cytomegalovirus were evaluated with 431 urine samples from 30 bone marrow and 88 kidney transplant recipients. Low-speed centrifugal inoculation was followed by early antigen (EA) detection by means of indirect immunofluorescence with a monoclonal antibody after 1 (EA-1) and 6 (EA-6) days of cultivation. The results were compared with those of conventional virus isolation (CVI). Of 68 positive samples, 49 (72%) were detected with EA-1, 58 (85%) were detected with EA-6, and 43 (63%) were detected with CVI. The combination of EA-1 and EA-6 showed positive results with 66 samples (97%), which is significantly better than with CVI (P less than 0.001). With the exception of one patient, all CVI-negative but EA-positive samples had either significant rises in immunoglobulin G (IgG) or IgA antibody titer or IgM antibodies present in the sera. These data indicate that the method with EA detection can replace CVI, provided that each sample is inoculated in duplicate. Sample 1 is examined after 1 day, and if it is negative, sample 2 is incubated for a further 5 days, followed by detection of cytomegalovirus.

Antigens, Surface↗
PubMed1987

Antibody isotype response after human cytomegalovirus infection.

The antibody isotype response to human cytomegalovirus (CMV) was studied in paired sera from patients with primary and recurrent CMV infection. The majority of sera was obtained from immunocompromised patients. In the 48 patients with primary CMV infection, CMV-specific IgM (CMV-IgM) and IgG (CMV-IgG) antibodies were found in all patients, and CMV-specific IgA (CMV-IgA) and IgE (CMV-IgE) antibodies in 46 patients. CMV-IgM, -IgA, and -IgE antibodies were found in, respectively, 21, 31 and 4 of the 53 patients with recurrent CMV infection, and in, respectively, 3, 3 and 1 of the healthy controls. The results indicate that CMV-IgE is a better marker of primary CMV infection than CMV-IgM, and confirm that detection of CMV-IgM and -IgA may also be useful for diagnosis of recurrent CMV infection.

Antibodies, Viral↗
PubMed1987

A sensitive enzyme-linked immunosorbent assay for the detection of herpes simplex virus antigens.

A sandwich ELISA for the detection of herpes simplex virus (HSV) antigens was developed using sheep anti-HSV F(ab')2 fragments for capture and an indirect antibody system for detection. Current detection limits are 0.5 ng protein for HSV1 and 1.5 ng protein for HSV2. This compares to a single HSV1-infected Vero-cell in a background of 10(6) non-infected cells or 10 plaque forming units (PFU) of HSV1 in culture supernatants as determined in separate experiments. Limiting dilution experiments show that one PFU of HSV1 can be detected after overnight culture in both supernatant and cell extracts. The use of F(ab')2 for capture completely eliminated binding of Staphylococcus aureus. No cross-reactivity was observed with other human herpes viruses. When evaluated with 245 random 'left-overs' of genital swab specimens in transport medium the test showed a sensitivity and specificity of 77.2 and 97.8%, respectively, with respect to virus isolation in culture. In a preliminary study on 16 direct ELISA swab-specimens extracted in 0.5 ml ELISA sample buffer both sensitivity and specificity were 100% with respect to culture. In both clinical series there was a proportional relationship between the ELISA value and the estimated amount of infectious virus in the specimen.

Animals↗
PubMed1987

Comparison of in situ DNA hybridization and immunological staining with conventional virus isolation for the detection of human cytomegalovirus infection in cell cultures.

The sensitivity of immunochemical staining and in situ DNA hybridization for the detection of human cytomegalovirus (HCMV) was compared with that of virus isolation. Human diploid fibroblasts were infected with serial, 10-fold dilutions of HCMV strain AD169 and examined at various intervals between 1 and 42 days after inoculation, using the three methods being compared. HCMV-DNA was detected by in situ hybridization using a biotin-labeled HCMV probe and CMV early antigen (EA) by immunochemistry using a specific monoclonal antibody. During the first 2 days after inoculation detection of EA appeared to be the most sensitive method. After the fifth day the sensitivity of the immunochemical and in situ hybridization methods was similar and equalled that of conventional virus isolation. However, 2-5 times more HCMV-DNA than HCMV-EA positive cells were detected. Our results indicate that both detection of HCMV-EA by immunological staining and HCMV-DNA by in situ hybridization are suitable methods for rapid and sensitive detection of HCMV infections.

Antigens, Viral↗
PubMed1987

Rapid diagnosis of herpes encephalitis by enzyme immuno-assay.

Five cases of encephalitis caused by herpes simplex virus (HSV) are described. HSV-specific IgM and IgM antibodies were detected in cerebrospinal fluid and serum by use of antibody-capture noncompetitive enzyme-linked immunosorbent assay. The tests seem suitable for rapid diagnosis in the second week after onset of neurological symptoms. The clinical importance of early diagnosis and therapy in patients of HSV encephalitis has been discussed.

Adolescent↗
PubMed1987

Interlaboratory evaluation of indirect enzyme-linked immunosorbent assay, antibody capture enzyme-linked immunosorbent assay, and immunoblotting for detection of immunoglobulin M antibodies to Toxoplasma gondii.

One hundred and fifteen serum samples from healthy laboratory personnel and 50 consecutive samples from 19 patients with anamnestic clinical signs of toxoplasmosis were assayed by four laboratories for the presence of immunoglobulin M antibodies to Toxoplasma gondii by an indirect enzyme-linked immunosorbent assay (ELISA), an antibody capture assay with peroxidase-labeled toxoplasma antigen, and an immunoblotting assay. In addition, a commercially available antibody capture ELISA was used. Highly significant correlation coefficients were obtained between the four laboratories and the commercial test. The indirect ELISA and antibody capture ELISA showed equal sensitivity in detection of immunoglobulin M antibodies to toxoplasma in early-stage serum samples. However, in this study, the antibody capture assay discriminated better between serum samples obtained at early or late stages of toxoplasma infection.

Animals↗
PubMed1987

Effect of cytomegalovirus infection on T-lymphocytes after lymphocyte-depleted bone marrow transplantation.

The effect of cytomegalovirus (CMV) infection on the repopulation of the peripheral blood with T-lymphocytes was studied in recipients of lymphocyte-depleted bone marrow transplants (BMT) who had hematologic and cytogenetic evidence of engraftment. Lymphocyte depletion was performed using counterflow centrifugation and resulted in a median depletion of 98.4% (range 94.4%-99.8%) of the T cells. Between 8 and 105 days after BMT, the T-cell repopulation was characterized by a relative preponderance of T cells lacking the CD3 marker and a slow repopulation of CD3+, CD4+, and CD8+ T cells. The CD8+ T cells repopulated at a faster rate in patients with CMV infection than in those not infected with CMV. At the end of the 9- to 12-month follow-up period, patients with CMV infection had normal numbers of CD4+ and CD8+ T cells but increased numbers of HNK1+ T cells. Those without CMV infection had subnormal numbers of CD4+ T cells, normal numbers of CD8+ T cells, and numbers of HNK1+ T cells that attained the upper limit of the normal range. Most of the HNK1+ T cells in both patient groups coexpressed the CD8 marker. We conclude that the occurrence of CMV infection in recipients of lymphocyte-depleted BMT is associated with an increase in the number of T cells coexpressing CD8 and HNK1, just as in recipients of nondepleted BMT.

Adolescent↗
PubMed1985

Detection of hepatitis B virus DNA in serum and relation with the IgM class anti-HBc titers in hepatitis B virus infection.

Sera from four groups of patients wtih different serologic markers of HBV infection were examined for HBV DNA using molecular hybridization technique and for IgM class anti-HBc using an ELISA based on the antibody capture principle. Results of HBV DNA assay were generally in good agreement with the presence of HBeAg. However, HBV DNA was found in 13% of anti-HBe+ sera and in one patient with anti-HBc as a sole marker. IgM anti-HBc was detected at high titers in acute hepatitis B patients and was also present during the "window-period." This marker was also found, though less frequently when other markers for HBV infectivity were absent, in chronic hepatitis B patients and healthy carriers. From these findings we conclude that the HBV DNA assay provides a reliable method of detecting the infectious agent, particularly in anti-HBe+ sera and sera with anti-HBc as a sole marker. The assay for IgM anti-HBc is useful for establishing the diagnosis of recent infection in patient with anti-HBc as a sole marker, and during acute hepatitis with very high aminotransferase values, a condition in which HBV DNA may be undetectable.

Acute Disease↗
PubMed1985

Use of enzyme-labeled antigen for the detection of immunoglobulin M and A antibody to herpes simplex virus in serum and cerebrospinal fluid.

A direct enzyme-linked immunosorbent assay (ELISA that used peroxidase-labeled antigen) was developed for detection of IgM and IgA antibody to herpes simplex virus (HSV). The assay uses immuno-affinity-purified antihuman IgM or IgA antibody-coated wells of microtiter plates to separate IgM or IgA from other classes of antibody in serum or cerebrospinal fluid (CSF). The presence of specific IgM or IgA is detected by subsequent, consecutive incubation with peroxidase-labeled antigen and substrate. HSV antigen was purified by sucrose gradient centrifugation and coupled with peroxidase by the periodate method. By examining sucrose-gradient-fractionated sera the assays were shown to be specific for IgM and IgA classes of antibody. None of the sera from patients with Epstein-Barr virus (n = 20), cytomegalovirus (n = 20), or varicella-zoster virus (n = 8) infection or with both rheumatoid factor and IgG antibody to HSV (n = 13) reacted positively. Only one out of 78 sera from healthy persons was positive for IgA antibody to HSV, and none for IgM antibody. All 33 patients with HSV infection developed HSV-IgA, 22 developed HSV-IgM. Of the 11 patients with primary infection, all had IgM antibody in their first sera and six had IgA antibody. The corresponding figures for the 22 patients with recurrent infection were five and nine. Furthermore, HSV-IgA antibody was found in serum and CSF of all five patients with HSV encephalitis in the second week after onset of symptoms, indicating the usefulness of the assay as a noninvasive technique for diagnosing HSV encephalitis.

Antibodies, Viral↗
PubMed1985

Absence of detectable hepatitis B virus DNA in sera and liver of chimpanzees with non-A, non-B hepatitis.

The risk of hepatitis B infections has been reduced by screening of blood donors for hepatitis B surface antigen (HBsAg). However, recipients remain at significant risk of developing post-transfusion hepatitis. Studies have shown that non-A, non-B hepatitis virus(es) are responsible for the majority of post-transfusion hepatitis infections. In spite of many efforts, these non-A, non-B hepatitis viruses have not yet been identified. Epidemiological studies, however, suggest that non-A, non-B hepatitis shares many features with hepatitis B. Recently, Wands et al [1982] showed, in chimpanzees infected with non-A, non-B hepatitis agents, the presence of antigenemia or viremia by radioimmunoassay with monoclonal antibodies directed toward distinct determinants of HBsAg and by molecular hybridization analysis. They suggested that non-A, non-B hepatitis agents may be related, but distinct variant(s) of hepatitis B virus (HBV). In this study, five chimpanzees were inoculated with three different agents that have been shown to transmit non-A, non-B hepatitis. The following inocula were used (I) a factor VIII preparation kindly provided by D.W. Bradley, (II) acute phase serum from a chimpanzee infected with the F strain kindly provided by A.J. Zuckerman, and (III) a DS-antigen serum previously shown by us to transmit non-A, non-B hepatitis [Duermeyer et al, 1983]. All chimpanzees developed a rise in transaminase levels between 8 and 10 weeks after inoculation. None of the chimpanzees was positive for any markers of HBV infection. No evidence was obtained of infection with hepatitis A, cytomegalovirus, or Epstein-Barr virus. One chimpanzee developed chronic liver disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗