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Biomedical subjects

T Kyaw

Publications and source records attributed to T Kyaw.

8 recordsLinked to original sources
PubMed2005

Seronegative conversion in four Neospora caninum-infected cows, with a low rate of transplacental transmission.

Four Neospora-seropositive pregnant cows (prebreeding indirect fluorescent antibody (IFA) titers between 1:400 and 1:1600) were confined and observed until parturition. All cows gave birth to normal calves. Selected tissues were tested for NC by histopathology, immunohistochemical (IHC) and polymerase chain reaction (PCR). Parasite isolation was attempted in vero cell cultures. At parturition, all cows were seronegative at 1:200 and two of four cows had a titer of 1:100 when further tested. Three of four calves were not infected, as determined by negative results of precolostral serology (1:25 cut-off), histopathology, IHC and PCR. One calf was congenitally infected, as shown by the presence of a thick-walled cyst labelled by IHC in its brain, positive PCR of brain and a precolostral IFA titer of 1:100. It was concluded that NC antibody titers may drop or convert to seronegative status in chronically infected cows by the time of parturition and this finding in four of four cows indicates that this could be a common occurrence. Similarly, the finding of an infected calf with a low antibody titer indicates that precolostral serology may not be a fool-proof means of identifying calves with congenital Neospora caninum infections. These findings call into question conclusions of other studies that have estimated rates of congenital transmission of this parasite based on serological tests at calving. This study is the first confirmed report of congenital NC infection in a calf in Thailand.

Animals↗
PubMed2004

Neospora caninum seroprevalence in dairy cattle in central Thailand.

The seroprevalence, in dairy cattle, of antibodies to Neospora caninum, the relationship between seropositivity and age (heifer versus cow), the relationship of herd infection with herd size and the relationship of herd infection with the presence of dogs on the farm were studied. The study involved 549 cows and 82 dogs in 59 dairy herds in Nakhon Pathom, Thailand. A competitive enzyme-linked immunosorbent assay (cELISA) with NC-specific monoclonal antibody was used to detect the NC antibodies in the sera. Individual and herd seroprevalence of NC were 5.5% (30/549) and 34% (20/59), respectively. No significant relationships between NC seropositivity with the age of the cows (heifer versus cow; P > 0.05) and between herd infection and the presence of dogs on the farm (P > 0.05) were found. Herd size significantly affected herd infection (P < 0.05) with higher infection in large than small herds (> or = 21 versus < or = 20 cows). Of 12 cows with a history of abortion, one was seropositive to NC. The seroprevalence of NC antibodies in dogs was 1.2% (1/82). This is the first NC seroprevalence study in dogs in Thailand. It was concluded that Neospora infection was more common at the herd level rather than the individual level in Thailand and the presence of dogs on the farm was not related to the level of herd infection. Caution should be taken in the interpretation of serological tests from the farm dogs.

Age Factors↗
PubMed1997

The prevalence of Enterocytozoon bieneusi in acquired immunodeficiency syndrome (AIDS) patients from the north west of England: 1992-1995.

Microsporidia are increasingly being recognised as important enteric pathogens in patients with advanced human immunodeficiency virus (HIV) disease, i.e. acquired immunodeficiency syndrome (AIDS). The aims of this study were to investigate the frequency of detection of microsporidia associated with diarrhoea in patients with advanced HIV disease in the north west of England, and to determine the species involved and their prevalence. During the period from April 1992 to the end of December 1995, chronic diarrhoea in 88 patients in the late stage of HIV disease was investigated. Duodenal biopsies, duodenal aspirates or jejunal biopsies were received from 38 patients, and stool samples from 63 patients, as part of the routine investigation of possible causes of diarrhoea in these patients. Biopsies and aspirates were examined by thin-section electron microscopy (EM), and stool samples were examined by epi-fluorescence microscopy after staining with Calcofluor. Putative stool positives were confirmed by transmission electron microscopy. CD4-lymphocyte counts were available from all patients who provided samples. Nine out of 63 patients (14.3%) were found to be excreting microsporidial spores on stool examination. The species was confirmed as Enterocytozoon bieneusi. The mean CD4-lymphocyte count for this group was 37 x 10(6)/L (normal range 517-1677 x 10(6)/L). Three out of 38 biopsy specimens (7.9%) were also found to be infected with this microsporidian. The mean CD4-lymphocyte count for this group was 72 x 10(6)/L. Encephalitozoon intestinalis was not found in any samples examined. The prevalence of microsporidial infection in AIDS patients in the north west of England appears to be similar to that of patients in London, but less than that reported in studies from other developed countries.

AIDS-Related Opportunistic Infections↗
PubMed1988

Immunomodulatory effect of bovine PTH extract on lymphocyte response to plant mitogens.

Human peripheral blood lymphocytes were incubated in the presence of various concentrations of bovine parathyroid hormone extract (PTH) or with PTH plus different concentrations of plant mitogens (PHA, Con-A and PWM) to determine whether PTH can modulate lymphocyte proliferation. Lymphocyte proliferation was assessed by 3H-thymidine incorporation into the lymphocytes after a 72-96 h incubation period. After initial inhibition, PTH stimulated lymphocyte proliferation at concentrations of 0.25-0.5 micrograms/0.2 ml and inhibited 3H-thymidine uptake at concentrations of greater than 1 microgram/0.2 ml. Similar responses were seen when the lymphocytes were incubated with PTH plus PHA. In contrast, PTH inhibited 3H-thymidine uptake by the lymphocytes when the cells were stimulated with Con-A (0.25-2 micrograms/0.2 ml) and PWM (0.25-2 micrograms/0.2 ml). The suppressive effects of PTH were not due to loss of lymphocyte viability as determined by trypan blue exclusion. It is speculated that the PTH mediated immunomodulatory effect on peripheral blood lymphocytes may be due to PTH itself or to some other factor(s) in the extract. In view of the common embryonic origin of the parathyroid glands and the thymus, the possibility that thymic-like hormones may be involved in the immunomodulatory process cannot be excluded.

Adult↗
PubMed1986

The renin-angiotensin system in hypothyroidism of short duration.

In six hypothyroid patients (2 male, 4 females, ages 22 through 59 years), plasma renin activity (PRA) and aldosterone (Aldo) were measured when the patients were euthyroid on levothyroxine therapy and one month after the therapy was stopped. Colonic mucosal potential differences were measured during the hypothyroid and euthyroid stages, and catecholamine sensitivity was determined by the blood pressure response to infused norepinephrine. Significant differences were observed in the PRA and aldosterone concentrations which were 4.1 +/- 2.5 ng/ml/h and 9.4 +/- 5.9 ng/dl, respectively in the hypothyroid stage and 6.9 +/- 2.3 ng/ml/h and 15.2 +/- 7.3 ng/dl, respectively when the patients were made euthyroid. The colonic mucosal potential differences (which reflect increased endogenous mineralocorticoid activity), became more electronegative after correction of hypothyroidism (-16.8 +/- 7.5 mV vs -32 +/- 18.2 mV; P less than 0.04) concentrations. Statistically significant decreases in norepinephrine pressor effects were observed in hypothyroid patients when compared to the euthyroid state (7.4 +/- 2.3 vs 10.9 +/- 1.9 micrograms/ng/min; P less than 0.01). It is concluded that patients with hypothyroidism have a hormonal pattern reminiscent of "low renin hypertension", and exhibit decreased sensitivity to catecholamines. Such changes are corrected when the patients become euthyroid on levothyroxine therapy.

Adult↗
PubMed1986

Interaction between gabaergic and opioid pathways in the regulation of gonadotropin secretion in males.

The effects of naloxone infusion given together with an infusion of LRH on gonadotropin secretion, were studied in 6 normal male volunteers before and after pretreatment with the GABA-transaminase inhibitor, valproic acid. In concordance with previous studies, naloxone infusion augmented the LRH-stimulated secretion of LH. Baseline serum LH concentrations were not significantly different after valproic acid pretreatment compared to control values. Similarly, valproic acid pretreatment failed to blunt the naloxone-augmented LRH-stimulated secretion of LH. Our data suggest that the previously reported animal studies on the central suppressive effect of GABA on endogenous LRH release is less prominent than the suppressive effect of opioidergic regulatory mechanisms in the human male.

Adult↗
PubMed1985

Acute suppurative thyroiditis.

A 25 year old woman suddenly developed pain in a neck mass which had been present for 10 years. Aspiration of a large cyst revealed by ultrasonography produced blood stained fluid from which E. coli was subsequently grown. Acute suppurative thyroiditis is the least common inflammation of the gland, and E. coli infection has been reported only once before in the past decade. A technetium scan is helpful in distinguishing acute from subacute thyroiditis.

Acute Disease↗