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Biomedical subjects

M Yadav

Publications and source records attributed to M Yadav.

At least 55 records · Page 3Linked to original sources
PubMed1991

Antibody reactivity with two strains of human herpesvirus-6 in Malaysians.

A total of 234 sera from healthy Malaysians of diverse ethnic origins were tested for antibody to the Z29 and prototype GS strains of HHV-6. The prevalence in the races ranged from 58 to 80% for the GS strain and 49 to 76% for the Z29 strain. The highest prevalence was in Malays with semi-urban cultural lifestyles and lowest was in the indigenous rural tribes (Ibans, Kadazans, Bidayuhs, and Orang Asli). The antibody titres to GS and Z29 virus capsid antigens differed in 11 (4.7%) samples by more than 2 dilutions. In 9 of the 11 sera the titres to GS strain were higher than to the Z29 strain. The differences in the antibody titres between strains of HHV-6 may reflect subtle changes in antigen structure of the virus recognised by some individuals.

Adult↗
PubMed1991

Dengue haemorrhagic fever and dengue shock syndrome: are they tumour necrosis factor-mediated disorders?

A consecutive series of 24 patients with clinical features of primary dengue infection and 22 controls (14 patients with viral fever of unknown origin and 8 healthy subjects) were assayed for serum levels of tumour necrosis factor (TNF). The acute sera of the 24 patients with clinical dengue infection were positive for dengue virus-specific IgM antibody. Clinically, 8 had dengue fever (DF), 14 dengue haemorrhagic fever (DHF) and 2 dengue shock syndrome (DSS). All 16 patients with DHF/DSS had significantly elevated serum TNF levels but the 8 DF patients had TNF levels equivalent to that in the 22 controls. A case is made for augmented TNF production having a role for the pathophysiological changes observed in DHF/DSS and mediator modulation as a possible therapeutic approach to treatment.

Adult↗
PubMed1991

Endogenous tumor necrosis factor-alpha in patients with nasopharyngeal carcinoma.

Serum tumor necrosis factor alpha (TNF) concentration was assayed in 105 patients with nasopharyngeal carcinoma using a sensitive ELISA technique with detection level of 10 pg/ml. The TNF levels were detectable in 45 of 63 (71.4%) patients newly diagnosed for the malignancy and 29 of 42 (69%) patients in remission following treatment with radiotherapy. In 25 normal controls the TNF were less than 10 pg/ml. While TNF may be present in the majority of the patients with the malignant disease, the TNF concentration appeared to have no clinical significance in diagnosis or prognosis of the patients.

Adult↗
PubMed1990

Relationship between immunoglobulin allotypes and susceptibility to nasopharyngeal carcinoma in Malaysia.

The relationship between immunoglobulin allotypes and risk of developing nasopharyngeal carcinoma was examined in a comparative study of 50 Chinese cases and 140 Chinese controls and 50 Malay cases and 79 Malay controls residing in Malaysia. Although the most common Gm phenotype was elevated in both Chinese and Malay nasopharyngeal carcinoma patients compared to their controls, there were no significant differences between cases and controls in the distribution of Gm haplotypes in either population. There were no differences between cases and controls in the distribution of Km alleles in either population. Thus a previously reported association of Km(1) with increased nasopharyngeal carcinoma risk in Tunisia is not confirmed in two Mongoloid populations in Malaysia.

China↗
PubMed1990

Low prevalence of antibody to human herpesvirus-6 (HHV-6) in Kadazans.

The prevalence of antibody to human herpesvirus type 6 (HHV-6) and Epstein-Barr virus (EBV) viral capsid antigens (VCA) were analysed in sera from Kadazans of Sabah, North Borneo. At a serum dilution of 10, about 34% were positive for HHV-6 antibody but in contrast all 95 individuals studied were positive for EBV VCA antibody. The study shows that HHV-6 and EBV infection occur independently. The low frequency of seropositive individuals in this community suggests that other than socioeconomic factors are responsible for the spread of the virus.

Adolescent↗
PubMed1989

Rectal mucosa in cows' milk allergy.

Eleven infants who were suspected clinically of having cows' milk protein sensitive enteropathy were fed with a protein hydrolysate formula for six to eight weeks, after which they had jejunal and rectal biopsies taken before and 24 hours after challenge with cows' milk protein. When challenged six infants (group 1) developed clinical symptoms and five did not (group 2). In group 1 the lesions developed in both the jejunal mucosa (four infants at 24 hours and one at three days), and the rectal mucosa, and the injury was associated with depletion of alkaline phosphatase activity. Infants in group 2 were normal. It seems that rectal injury that develops as a direct consequence of oral challenge with the protein in reactive infants may be used as one of the measurements to confirm the diagnosis of cows' milk protein sensitive enteropathy. Moreover, ingestion of such food proteins may injure the distal colonic mucosa without affecting the proximal small gut in some infants.

Alkaline Phosphatase↗
PubMed1989

Changes in complement C3 levels following treatment of patients with Brugia malayi infection.

Serum IgG levels and complement C3 levels were assayed on Day 0, 1, 3-4, 7 and 56-70 post-treatment with diethylcarbamizine citrate (DEC) in a series to 26 patients with Brugia malayi infection and 6 volunteers without infection. On treatment, the microfilariae were cleared from the blood within 24 hours. The eosinophils decreased dramatically on Day 1 post-treatment but increased rapidly by Day 4 to 7 and then dropped to normal levels in 45 days. The serum IgG mean levels decreased briefly following treatment with DEC but then returned to original levels. However, the complement C3 levels gradually increased over the 2 months period of study reaching statistical significance levels (p less than 0.01) in patients with initial high blood microfilariae. The observation suggests that Brugia malayi infection probably induces a high rate of synthesis of complement C3 and this process continued in the post-treatment phase. Since, DEC treatment did not cause a decrease in complement C3 with the elimination of blood microfilariae, it would appear that the complement C3 is consumed following antibody attachment to the microfilariae as they enter the blood circulation.

Adult↗
PubMed1988

Expression of Epstein-Barr virus-encoded proteins in nasopharyngeal carcinoma.

Expression of the Epstein-Barr virus (EBV) encoded nuclear antigens (EBNA 1 to 6) and membrane-associated protein (LMP) was investigated by immunoblotting in 83 nasopharyngeal carcinoma (NPC) biopsies and 25 other tumor and normal tissue specimens from the head and neck region. Fifty-eight of the 83 NPC biopsies were large enough to yield parallel data on virus DNA and viral expression. All 16 cases of clinically diagnosed and histologically confirmed NPCs from North Africa contained EBV DNA and expressed EBNA-1. Of 31 clinically diagnosed NPCs from China, 29 contained EBV DNA and 25 of these expressed EBNA-1. One control tissue biopsy from the oropharynx of NPC patients contained EBV DNA, but none expressed EBNA-1. The latent membrane protein (LMP) was detected in 22/31 of the Chinese and in 10/16 of the North African NPC biopsies. None of the NPC biopsies or control tissues expressed detectable amounts of EBNA 2 or any of the other 4 nuclear antigens which are invariably expressed in EBV-transformed B cells. A smaller number of tumors from Malaysia and East Africa exhibited a similar pattern of expression. EBV was rescued from a nude-mouse-passaged North African NPC tumor by co-cultivation of the tumor cells with umbilical cord blood lymphocytes. The tumor expressed EBNA 1 and LMP, but not EBNA 2 or the other 4 EBNAs. The resulting LCLs expressed all 6 nuclear antigens, EBNA 1 to 6 and LMP. Our data suggest that expression of the EBV genome is regulated in a tissue-specific fashion.

Animals↗
PubMed1988

Effect of continued feeding of cows' milk on asymptomatic infants with milk protein sensitive enteropathy.

The clinical response and the histological changes in the mucosa of the small bowel in response to continued feeding with cows' milk protein were assessed over a period of 2-6 weeks in 24 infants who had shown histological changes without immediate clinical symptoms after challenge with a diet containing cows' milk protein. Twenty of the 24 infants (83%) thrived well on cows' milk protein. Jejunal biopsy specimens taken six to eight weeks after the initial biopsy showed histological improvement in all 20 infants compared with biopsy specimens taken soon after the challenge, which had shown mucosal damage. The mucosa had returned to normal in 12, was mildly abnormal in seven, and moderately abnormal in one. Corresponding improvements in the activities of mucosal enzymes were seen. In four of the 24 infants (17%) symptoms developed between three and six weeks. Histological examination of the jejunal biopsy specimens showed that mucosal damage had progressed in two, and remained the same in two; moreover, the disaccharidase activities remained depressed. The present study shows that most infants with enteropathy caused by sensitivity to cows' milk protein but without clinical symptoms develop tolerance to the protein and the mucosa returns to normal despite continued feeding with cows' milk protein.

Animals↗
PubMed1985

Isolation and partial characterization of the extracellular polysaccharides and lipopolysaccharides from fast-growing Rhizobium japonicum USDA 205 and its Nod- mutant, HC205, which lacks the symbiotic plasmid.

The extracellular polysaccharides and lipopolysaccharides (LPSs) from two fast-growing Rhizobium japonicum strains, USDA 205 and HC205, were isolated and partially characterized. Strain HC205 is a Nod- mutant of USDA 205 which lacks the symbiotic plasmid. The extracellular polysaccharides from both strains are very similar in composition, having galactose, glucose, glucuronic acid, and acyl groups. The extracellular polysaccharides do not contain detectable levels of pyruvate. Methylation analysis shows that the extracellular polysaccharides from both strains have the same glycosyl linkages. The LPSs were purified by a modified phenol-water extraction procedure and gel filtration chromatography. The LPSs from USDA 205 and HC205 elute as broad peaks from the gel filtration column and contain 2-keto-3-deoxyoctonic acid as one of the major sugar components. Each broad 2-keto-3-deoxyoctonic acid-containing peak has a distinct shoulder on its leading edge. The shoulder and the remainder of the broad peak are separated and labeled LPSI and LPSII, respectively. Glucose (and 2-keto-3-deoxyoctonic acid) is a major sugar in the LPSI fractions. Both the LPSII fractions contain 2-keto-3-deoxyoctonic acid as the major sugar (about 20% of the mass). There are a number of quantitative differences in these LPS fractions between strain USDA 205 and HC205. Polyacrylamide gel electrophoresis shows that the LPSs are heterogeneous molecules but less heterogeneous than the LPSs from Salmonella minnesota or Rhizobium leguminosarum. The LPSI fractions from both USDA 205 and HC205 show a single lower-molecular-weight band and a higher-molecular-weight banding region which contains several bands. No bands are observed for the LPSII fractions from either USDA 205 or HC205.

Carbohydrates↗
PubMed1984

Malaria antibody levels in patients with nasopharyngeal carcinoma.

The antibody titres to P. falciparum and Epstein-Barr Virus-associated antigens were assayed in 22 patients with NPC and 43 controls. All, but one patient had antimalarial titres; 14 had titres greater than 80 and 4 patients greater than 640. Compared to controls the mean anti-malarial titre for most age groups were higher in the patients. Those patients with high anti-malarial titres also had high IgA anti-VCA titre, an antibody which has been demonstrated to be diagnostic for NPC. The peak anti-VCA (IgG) and anti-EA (IgG) antibody titres were associated with anti-falciparum titres of 320-640 and 80-160, respectively. The results are discussed in relation to the possible association between malarial infection and etiology of NPC.

Adolescent↗
PubMed1984

Nasopharyngeal carcinoma in Malaysians under the age of 20 years.

A total of 52 cases of NPC were found in a five-year survey from 1978 to 1982 in Malaysia. The annual rate of occurrence was 3.4, 3.0, 2.4 and 1.8 for Chinese, Malays, Kadazans and Sarawakians, respectively. The age-specific incidence rates per 100 000 were highest for Kadazans (2.34 to 7.59) in comparison to the other races (0.11 to 1.24). The proportion of NPC in young Malaysians formed 1.2% in Chinese, 7.2% in Malays and 6.9% for others. A sexual bias was present in Chinese (male:female = 2.2) and Sarawakians (1.7) but not in Kadazans and Malays (0.9). In most Chinese, the primary tumour histologically is of the poorly differentiated characteristic and this type is the predominant tumour in the country. The Kadazans presented with well differentiated primary tumour and the Malays with all three histological types i.e. well-, poorly- and undifferentiated. At first examination enlarged lymph nodes were found in 95.7% of the patients and 65.2% had epistaxis and growth in the postnasal space. Antibodies to IgA anti-VCA were present in half of the 6 patients serologically studied.

Adolescent↗
PubMed1982

Egg-protein-induced villous atrophy.

The effect of egg protein on the small bowel mucosa of a 9-month-old infant with a history of intolerance to egg protein was studied. Within 24 h of ingestion of egg protein marked villous atrophy, depletion of mucosal oligosaccharidases, impaired absorption of xylose, and depressed serum complement levels were observed. The study demonstrates that egg protein is yet another cause of flat mucosa of the small intestine in infants.

Atrophy↗
PubMed1982

Adoptive transfer of immunity to Plasmodium berghei with spleen cells from drug cured mice.

Plasmodium berghei infection gives rise to a fatal fulminating parasitaemia in mice. Resistance to the infection can be achieved if the mice are allowed to recover from the blood-induced infection by administration of chloroquine. In CBA/Caj, one cycle and in Balb/c mice, at least, two cycles of infection, alternating with drug-cure were necessary for the establishment of immunity. No parasitaemia was seen following further challenges after the third infection. Adoptive transfer of spleen cells from the immune mice showed that immunity could be transferred by 50 to 70 x 10(6) cells. On challenge the recipients develop high parasitaemia which was cleared in less than 5 weeks. Recipient mice given low number of spleen cells did not survive. The transfer of immune spleen cells depleted of either T or B lymphocytes abrogated the protective effect. Comparatively T lymphocytes were less effective in transferring protection than B lymphocytes. The study suggests that both humoral and cell-mediated effector mechanisms are needed for the maintenance of immunity in drug-cured immune mice.

Animals↗