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D O Ho-Yen

Publications and source records attributed to D O Ho-Yen.

At least 19 recordsLinked to original sources
PubMed1992

Use of the polymerase chain reaction to detect Toxoplasma gondii in human blood samples.

AIMS: To assess the value of detecting Toxoplasma gondii in human blood samples using the polymerase chain reaction (PCR). METHODS: Blood samples in lithium heparin were examined from 34 patients with suspected toxoplasmosis, and six healthy volunteers with or without the addition of doubling dilutions of toxoplasma tachyzoites. Products of a nested PCR, using oligonucleotide primers of the B1 gene, were analysed by electrophoresis and stained by ethidium bromide. The primary product was 194 base pairs in length; the nested products were 160 or 97 base pairs. RESULTS: When toxoplasma tachyzoites were added to the leucocytes of six different volunteers, eight to 16 parasites were detected by nested PCR in one experiment and one to four parasites in eight experiments. All nine experiments were negative in samples without added tachyzoites. Of 34 patients, PCR was negative in 13 with recent lymphadenopathy; nine with persisting IgM, including two pregnant patients; four with reactivated infection due to immunodeficiency; and five with no evidence of active infection. Positive PCR results were found in three patients with reactivated infection. There was only one discrepancy between PCR and animal culture results; this was in an immunocompromised patient with a positive PCR and negative culture. CONCLUSIONS: The PCR technique was rapid, sensitive, and specific in human blood samples. Negative PCR results in patients with persisting IgM suggested that the fetus was not at risk, or that treatment was not indicated in myalgic encephalomyelitis-like illness. PCR results in immunocompromised patients permitted appropriate management--no treatment if negative, treatment if positive.

Animals↗
PubMed1992

Comparison of relative uses of commercial assays for Toxoplasma gondii IgM antibodies.

AIMS: To compare the sensitivity and user friendliness of seven commercially available enzyme linked immunoabsorbent assay (ELISA) kits for toxoplasma specific IgM. METHODS: Five antibody capture assays supplied by Abbott, Mercia, Northumbria, Organon and Sorin, and two indirect ELISA assays from Biostat and Mast, were assessed. Using defined dilutions of Toxoplasma gondii specific IgM, the performance and sensitivity of each assay was established. They were further assessed on a panel of 27 sera with a range of dye test and IgM results (as determined by the Scottish Toxoplasma Reference Laboratory). All of the assays were performed by three experienced operators and assessed for user satisfaction. RESULTS: The Mast, Organon, and Abbott assays were of low sensitivity; the Mercia and Northumbria were of high sensitivity; and the Biostat and Sorin assays produced too many false positive results. The Mercia kit provided most user satisfaction; the Mast and Abbott assays were most difficult to use. CONCLUSIONS: Local laboratories investigating toxoplasma infection should have three tests: one IgG and two IgM (high and low sensitivity) to help in the timing of infection. Alternatively, one sensitive IgM assay, such as that of Mercia, could be used by selecting appropriate high and low thresholds.

Animals↗
PubMed1991

Comparison of IgG antibody profiles by immunoblotting in patients with acute and previous Toxoplasma gondii infection.

The IgG antibody profile to Toxoplasma gondii proteins of less than 37 kilodaltons in sera from patients with acute and previous infection was studied by immunoblotting. Bands at 28, 29, and 36 kilodaltons were more common in acute infection (10 out of 10, nine out of 10, and nine out of 10, respectively) compared with previous infection (five out of 10, four out of 10, and one out of 10, respectively). The 6 kilodalton band was present in 10 out of 10 sera from patients with acute infection and five out of 10 sera from those with previous infection. A new observation is a doublet of bands of 22-25 kilodaltons present only in sera from patients with acute infection. This doublet may be a more reliable indicator of acute infection than the 6 kilodalton band.

Acute Disease↗
PubMed1991

Natural killer cells and the post viral fatigue syndrome.

60 patients were referred with a diagnosis of post viral fatigue syndrome (PVFS), but only 50 fulfilled strict criteria for this illness. Many lymphocyte subpopulations were normal, but there was a spectrum of natural killer (NK) cell results: 20/50 (40%) were raised; 8/50 (16%) were low;, 5/50 (10%) were low initially but normal on repeat testing; 17/50 (34%) were normal. When patients were categorised on their NK cell results, there were significant differences in the two groups with raised or low NK cells compared to the "Not PVFS" group: the CD8 cells were increased (p less than 0.001, p less than 0.02) and the CD4/CD8 ratio was reduced (p less than 0.05) but the CD4 cells were normal. Clinical data showed that the "Not PVFS" group were older, with less severe illness, less muscle pain and less virological evidence of infection. It is postulated that patients have low NK cells initially and then progress to normal or raised levels dependent on factors such as stress, other infections and behaviour.

Adult↗
PubMed1991

General practitioners' experience of the chronic fatigue syndrome.

In order to examine the prevalence of patients with symptoms fulfilling the criteria for the chronic fatigue syndrome an extensive survey was carried out of general practitioners on 10 local government lists in two health boards (91% response rate). At the same time practitioners' attitudes to the syndrome and their experience in terms of workload and the characteristics of patients affected were documented. The majority of general practitioners (71%) accepted the existence of chronic fatigue syndrome, but 22% were undecided. The doctors reported a prevalence among their patients of 1.3 per 1000 patients (range 0.3-2.7 for the 10 areas) with a peak in the 30-44 years age group. Female patients were more commonly affected than males (sex ratio 1.8:1.0), but the severity of illness and the use of general practitioner's time was the same among male and female patients. Patients in occupations where they were exposed to infection were affected (teachers and students, 22% of sample; hospital workers, 7%), but many patients were unskilled (8%) and skilled workers (9%). Patients suffering from the chronic fatigue syndrome appear to be a real and distinct group for general practitioners and may represent a substantial part of the workload of doctors in particular areas.

Adult↗
PubMed1991

Suspected allergy: a sequential protocol for testing patients' sera.

Sera from 591 patients were examined for total IgE concentration and for reactivity against a panel of seven specific allergens, using the radio-allergosorbent test (RAST). As the total IgE increased, the frequency of positive RAST reactions increased (P less than 0.001); there were more multiple positive RAST reactions (P less than 0.001); and there was a higher grade of RAST reaction (P less than 0.001). However, 12% of patients with normal IgE levels were positive by RAST. From these data a sequential protocol for testing sera of patients with suspected allergy has been developed. Sera should first be tested for total IgE, RAST reactivity to grass pollen and house dust mite. Samples reactive in either assay should be tested with the remaining five discs of the full screen. This protocol reduces unnecessary tests, but allows identification of sera with positive RAST results.

Clinical Protocols↗
PubMed1990

Congenital toxoplasmosis: to screen or not to screen?

We have reviewed the present day quantifiable cost to society of the 73 cases of congenital toxoplasmosis which are estimated to occur annually in Scotland with the cost of preventing the disease by screening and treatment. Our analysis includes advances in laboratory techniques. The cost of screening would depend on its scale and if in-house or commercial tests are used. If only 2 specimens were screened, at booking and at delivery, the screening costs are estimated to be between 0.5-0.9 times the preventable costs. If a third specimen were tested in the second trimester, to maximise scope for remedial action during pregnancy, the screening costs are 0.7-1.2 times preventable costs. As likely screening costs in most of the schemes we consider are now less than the preventable costs, a screening programme should be adopted.

Cost-Benefit Analysis↗
PubMed1990

Assessment of rapid ELISA test for detection of Epstein-Barr virus infection.

A rapid test for the detection of IgM and IgG Epstein-Barr nuclear antigen (EBNA-1) has been extensively marketed. If IgM to Epstein-Barr viral capsid antigen (EBV VCA) is taken as evidence of current EBV infection, one observer detected 17 of 38 such samples and the other 22 of 38 as acute. The positive predictive value of the test was 63%, and the greatest difficulty was posed by the detection of IgM EBV VCA positive, heterophile antibody negative samples. Significant false positive results were obtained in sera with evidence of current Toxoplasma gondii, cytomegalovirus, and adenovirus infection. Rheumatoid factor was not a problem. Modification of the test protocol improved its performance: the positive predictive value rose to 87% and the negative predictive value to 81%. Although our modifications did not increase the speed of the test, there was reliable information on the EBNA-1 state. The test is best used as an adjunct to other EBV serology, and laboratories should be aware of the limitations of the rapid test.

Antigens, Viral↗
PubMed1990

Simultaneous diagnosis of toxoplasmosis in goats and goatowner's family.

Four out of 6 goats from a small British goat herd gave birth to weak or stillborn kids. All were seropositive for Toxoplasma gondii. The parasite was isolated from the tissues of one kid and the milk of one goat. Concurrently, one of the goatowner's sons developed a mononucleosis-like illness with serological evidence of current toxoplasma infection. Investigation of the family showed past infection in the other son, but both parents were seronegative. The source of infection for both boys appeared to be the consumption of unpasteurized goat's milk.

Adolescent↗
PubMed1990

Patient management of post-viral fatigue syndrome.

A case definition for post-viral fatigue syndrome is proposed within which various subgroups of patients exist. Any one treatment may not apply to all the subgroups. In particular, patients' experiences do not show that avoidance of exercise is maladaptive. It is proposed that the recently ill often try to exercise to fitness whereas the chronically ill have learnt to avoid exercise. Recovery is more likely to be achieved if patients learn about their illness and do not exhaust their available energy.

Adolescent↗
PubMed1989

Diagnosis of congenital toxoplasmosis in Scotland.

During a period of 10 years (1976-1986) 853 cases of toxoplasmosis were identified serologically in the Toxoplasma Reference Laboratory in Scotland. Suspected cases of infection in pregnancy (29 cases) and of congenital infection (27 cases) were rare but ophthalmic disease was common (224 cases). In two of the congenital cases, maternal infection was identified during pregnancy. The other 25 babies were investigated because of suspected congenital infection. Toxoplasmosis was confirmed retrospectively in 11/25 babies and excluded in two of them. The other 12 cases remain unclassified. Diagnosis of infection in babies was difficult although the introduction of an IgM capture ELISA was of some help. IgM was detected by ELISA in 3/13 congenitally infected babies but by immunofluorescence tests in only one of these. In two antenatal studies, involving 16,000 women, an additional 32 women were identified whose babies might have benefited from treatment or the availability of fetoscopy for early detection of congenital infection.

Animals↗