A seroepidemiological study of measles: Some practical implications for measles immunization program, Kingdom of Saudi Arabia.

It was hypothesized that the recent outbreaks of measles in a geographically defined area of Al-Qassim might reflect significant changes in the epidemiology of measles and cast doubt upon the real protective value of measles vaccines. Therefore, the two objectives of this research were to study some epidemiological parameters of cases of measles (n=993) and the current immunological status of immunized children (n=2810). The crossmatched data about measles patients were collected on an official proforma and 3 mL of blood were extracted from each child for determining the measles IgG and IgM antibodies. The results showed that female patients were significantly overrepresented (51.3%). The majority of patients encountered at primary health care centers (PHCCs) (81.3%) were more than five years of age (76.5%). Among nonvaccinated measles cases, 54.9% (n=402) were from rural/desert areas. The measles vaccine failure rate was 26.3%. The results of the surveyed children showed that 2% of them were not vaccinated. The measles IgM levels were detected significantly in recently vaccinated females (n=29/51, 56.9%). The measles IgG positivity unaffected by age, sex, and residence was found in 87.4% of children. A significant portion of children from rural/desert areas were not vaccinated (n=44/57, 77.2%). Though there were apparently high seroconversion rates in children under two years of age following Edmonston-Zagreb vaccine, overall it did not achieve any statistical significance when compared with seroconversion rates in all children following Schwartz vaccine. We conclude that besides at age six months, and MMR containing measles vaccine at 12 months, children at school entry (six years) should also be considered for measles vaccination.

Central adiposity and atherogenic lipids in Saudi diabetics.

A high caloric intake from fat sources and prevailing obesity in the Saudi population prompted this study. Waist to hip circumference ratio (WHR), fasting cholesterol, triglycerides and insulin were measured in 76 non-insulin dependent adult Saudi diabetics. Serum LDL, HDL and VLDL were measured in 45 of these diabetics. WHR of Saudi diabetics was higher (0.98 in males, 0.91 in females) than reported for diabetics from the West. Serum cholesterol levels (5.52 mmol/L in males, 5.98 mmol/l in females) were higher than reported in the past for normal Saudi subjects. Lipid profile was strikingly different in the two sexes. Male diabetics (n=28) had significantly higher WHR associated with elevated triglycerides and VLDL but a lower HDL/cholesterol ratio. Female diabetics (n=48) were obese and had healthier HDL levels. Interestingly, LDL cholesterol changed reciprocally with WHR in female diabetics. This preliminary study reveals the presence of significant central adiposity and an atherogenic lipid profile in Saudi diabetics. The sex differences in lipids indicates the need for studies involving lipoprotein metabolism in Saudis. Further, an increase in atherosclerosis-related disorders should be expected in Saudi diabetics.

Significance of tumour markers in colorectal carcinoma associated with Schistosomiasis.

Schistosomiasis as well as Colorectal Carcinoma are equally prevalent in Egypt. However, the role of Schistosomiasis as a risk factor for Colorectal Carcinoma is not well established. Three tumour markers have been assessed in 69 patients with large bowel disease. They were classified into five groups. Group 1 (A) included 21 cases with Schistosomal hepatic fibrosis. Group 2 (B) included 6 cases of ulcerative colitis. Group 3 (C) included 10 cases of adenomatous polypi of which 12 cases had Schistosomiasis. Group 4 (D) consisted of 21 cases of colorectal carcinoma, 12 cases had schistosomiasis in association with colorectal carcinoma constituting group 5 (E). Elevated CEA was observed in benign tumours but showed non significant difference in G4 and G5. Significantly increased AFP levels were evident in G1, G4, and G5. Significant increase of B-HCG was observed only in G4 and G5 indicating its significance as diagnostic index in case of malignancy. It has been observed that Schistosomal hepatic fibrosis induced increased levels of some of the tumour markers. Therefore, the factor of Schistosomal hepatic fibrosis should be considered during the assessment of tumour markers in colorectal carcinoma cases.

Growth of rat-mouse hybridomas in nude mice and nude rats.

Athymic (nude) mice and rats were inoculated intraperitoneally with rat-mouse hybridoma cells secreting monoclonal antibodies to rat MHC class I antigens in order to improve the yield of antibodies. Pristane priming and subsequent intraperitoneal injection of the hybridoma cells in to nude mice yielded ascites which contained antibody in high concentration (10-15 mg/ml). Complete Freund's adjuvant, mineral oil, pristane or antibody-antigen complexes were used to induce ascites in nude rats, but only pristane priming did so consistently. The hybridoma cells in the ascitic fluid failed to secrete antibody, although they contained intracellular antibody. However, when the pristane-primed nude rats received 250-500 rads of total body radiation prior to injection with the hybridoma cells, they produced large amounts of antibody. When the nude rats were splenectomized and injected with the hybridoma cells, they also produced antibody in high titers. There was no in vitro inhibition of antibody formation by the hybridoma cells cultured in medium containing 15% serum from nude rats, but co-culture of the hybridoma cells with splenic lymphocytes from normal or nude rats markedly inhibited antibody production. These results indicate that the defect in antibody secretion by the hybridoma cells in the ascites of nude rats is due to the presence of radiation-sensitive suppressor cells in the spleen.

Characterization of the T antigen and T agglutinin in inbred rats.

Treatment of rat erythrocytes with vibrio cholerae neuraminidase (VCN) exposed antigenic determinants on the cell surface membrane, and autologous rat serum contained antibodies which reacted with these determinants and with VCN-treated human erythrocytes. The antibodies were not present in sera of animals less than 8 weeks of age. Human serum also contained antibodies which reacted with the VCN-treated rat erythrocytes. Lectin isolated and purified from Arachis hypogoea agglutinated VCN-treated rat erythrocytes. This system has the characteristics of the T antigen which had been described initially in humans. Absorption studies showed that the VCN-treated rat erythrocyte membrane antigen cross-reacted with the VCN-treated human erythrocyte membrane antigen. Absorption of rat sera and the lectin solution with VCN-treated rat or human erythrocytes removed all of the molecules capable of reacting with both rat and human erythrocytes. Absorption of human sera with VCN-treated human cells removed their reactivity with both cell types, but absorption with VCN-treated rat cells did not remove completely their reactivity with VCN-treated human erythrocytes. These results indicate that the VCN-treated rat cells contain antigenic determinants which are identical to some on the VCN-treated human cells and that the human sera contain antibodies to additional antigenic specificities not shared with rat red blood cells. Haemagglutination inhibition studies with different sugars, T antigen from human erythrocyte membranes and desialylated glycoprotein from rat erythrocyte membranes showed that the T antigen, the desialylated glycoprotein and the sugars containing a terminal non-reducing beta-D-galactosyl residue inhibited the reactivity of the lectin, the rat sera and the human sera with both human and rat red blood cells. These findings show that the antigenic reactivity of the VCN-treated rat red blood cells residues in the membrane glycoproteins and that the immunodominant group is a carbohydrate. Thus, the rat has a T antigenic system very similar to that of the human.