Water droplet surface tension method - An innovation in quantifying saponin content in quinoa seed

Quinoa surface borne saponins are bitter tasting anti-nutritional compounds that must be removed before consumption of the seed. To determine saponin content, the currently available standard afrosimetric foam test method only determines the presence of saponin via a rating of either 'acceptable' or 'unacceptable'. A water droplet surface tension (WDST) based innovative method was developed that can quantify saponin content in aqueous solutions with greater accuracy. The method comprised four steps: solution preparation, droplet creation, image capture and image analysis using Axisymmetric Drop Shape Analysis computer software. The method applied satisfactorily to saponin content up to 0.2 mg.ml^-1 as higher concentrations did not further reduce the surface tension. Results demonstrated that saponin concentration may be measured in the range 0.05 to 0.15 mg.ml^-1 (0.05 - 0.15% saponin by weight of seed). Validation of the WDST method on commercial and experimental samples offers quinoa processors an accurate inexpensive way of measuring saponin concentration to satisfy current seed quality specifications.

A longitudinal study of hepatitis infection in an institution for the mentally retarded

The natural history of hepatitis A and B infections in a large institution for the mentally retarded were studied over an eight year period. Serum samples were obtained from most subjects on three occasions and tested for anti-HAV, HBsAg, anti-HBs and occasionally anti-HBc, by solid-phase radioimmunoassay. Hepatitis A was found to have been a common infection was 74.8% of subjects having detectable levels of antibody. The virus does not appear to be endemic, as the prevalence of antibody in children admitted since the last outbreak was no higher than amongst non-institutionalised children. The infection rate amongst subjects with Down's syndrome (DS) was higher than amongst subjects with other forms of mental retardation (OMR), and more than 95% of infections in both groups were unrecognised. By contrast with hepatitis A, hepatitis B virus was endemic in the institution with 81.2% of residents showing serological evidence of current or past infection. Of these, 40.8% of subjects with DS and 9.2% of those with OMR were found to be chronic carriers. The carrier rate was higher in males than females and tended to be more prolonged in subjects with DS. During the study period, the predominant subtype of HBsAg detected in the institution changed from adw to ayw.

The prevalence of HBeAg and anti-HBe in an institution for the mentally retarded

The age specific prevalence of HBsAg and anti-HBs was studied in 855 mentally retarded children and adults living in a large institution. The sera of every HBsAg positive patient was re-tested for the presence of HBeAg and anti-HBe. Overall, 78.2% of subjects showed serological evidence of current or past infection with HBV. The carrier rate was highest in children and young adults and higher amongst subjects with Down's syndrome than with other forms of retardation. HBeAg was detected in 33.9% of carriers and its prevalence also decreased with increasing age and was highest amongst subjects with Down's syndrome.

Levamisole: lack of immunopotentiation in a controlled trial

The immunopotentiating effect of levamisole was assessed in a double-blind trial in two comparable groups of patients with Down's syndrome, with which the immunodeficiency and susceptibility to infection are known to be associated. One group was given levamisole continuously and at the same dose for 16 weeks, and the other group was given placebo tablets. A checklist was designed to record the type, frequency, and duration of all infections which occurred in the patients, and delayed type hypersensitivity responses to various antigens were measured. There were no differences between the two groups in body weight, number of intercurrent infections, duration of illness, nor was there any change in degree of depression or cutaneous delayed-type hypersensitivity. These findings, taken with claims of success in some patients and failure in others, suggest that levamisole is not a general immunopotentiating agent, although it may have a specific site (or sites) of action on the immune system. If levamisole is to be used more selectively, this action needs to be characterized.

Prevalence of antibody to the hepatitis A virus in a large institution for the mentally retarded

The prevalence of antibody to hepatitis A virus (anti-HAV) was determined in 854 people living in a large institution for the mentally retarded in Melbourne. Altogether 638 (74.4%) of the subjects were found to have specific antibody detectable by solid-phase radioimmunoassay (SPRIA). No difference in antibody prevalence was observed between males and females; however, the prevalence was higher among subjects with Down syndrome (84.1%) than those of other forms of mental retardation (72.8%). In both groups there was an increase in prevalence of antibody with increasing age and duration of institutionalization. When compared with the open community, patients in this institution have a higher prevalence of antibody and appear to acquire their infections at an earlier age.

Stress deficiency of the T-lymphocyte system exemplified by Down syndrome

A comparison of immune competence in 26 patients with Down syndrome in an institution and 26 matched healthy controls revealed an atypical pattern of T-cell immunodeficiency in the Down-syndrome patients. The patients with Down syndrome had a lymphocytosis in blood with high counts of T (and B) cells, but with impaired effector function of T cells as judged by anergy to dinitrochlorobenzene, low responsiveness to ubiquitous antigens which elicit delayed-type hypersensitivity reactions, and low mitogenic activity of non-stimulated and phytohaemagglutinin-stimulated lymphocytes in culture. Helper-T-cell function measured by the humoral immune response to flagellin was intact, and there were minor abnormalities of the B-cell system. Attempted restoration of T-cell function with levamisole was unsuccessful. This pattern of T-lymphocytosis with impaired effector function could be explained by "stress-deficiency" of the immune system consequent upon a heavy load of infection in early life.