Determination of enteropeptidase activity in human duodenal aspirates.

A sensitive procedure is described for the determination in duodenal aspirates of enteropeptidase activity based on the activation of trypsinogen and the estimation of trypsin formed with benzoyl-arginine-p-nitroanilide. Using the recovery approach where a known amount of purified human enteropeptidase is diluted in duodenal fluid and the recoverable activity determined, this method was shown to give a sensitive and reliable estimate of the enteropeptidase activity in duodenal fluid although it was shown that the enzyme was subject to a 10% activation by components in the duodenal fluid. The reported 5-fold stimulation of enteropeptidase activity by bile salts could not be demonstrated.     

A new neocentromere locus on chromosome 13 resulting in mosaic tetrasomy for distal 13q and an asymmetric phenotype

An 8-year-old girl was referred to the Genetics Centre with mild developmental delay, mild dysmorphic features, and a head circumference on the 98th centile. She was noted to have large irregular ear lobes, torticollis, and mild hemihypertrophy. Karyotype analysis of cultured peripheral lymphocytes and skin fibroblasts revealed the presence of a symmetrical supernumerary marker chromosome in 13% of cells from both tissue types. Further analysis showed that this marker chromosome originated from the distal region of chromosome 13 and contained no centromeric alpha-satellite DNA. The marker chromosome was not found in blood from the parents. This case represents a novel symmetrical structure with a previously unreported neocentromere locus, leading to an unusual phenotype. Similar cases of individuals with a chromosome 13 with a neocentromere have been reported. They are reviewed and compared with the current case. The importance of scanning metaphases for abnormalities in individuals presenting with asymmetry is emphasized.     

Seroprevalence and demographic characteristics of injection drugs users among individuals at risk for HIV infection in Winnipeg, Manitoba, Canada.

From June 1986 to March 1990, a prospective seroprevalence survey and questionnaire of individuals at risk for HIV infection was conducted with volunteers in Winnipeg. Of 610 individuals enrolled, 146 were injected drug users (IDU). Fifteen IDU were in a methadone treatment program and all were seronegative. Three of 131 remaining IDU were HIV-1 seropositive (2.3%), a rate similar to 2.2% positive (20+ of 927) in diagnostic specimens from IDU tested in the province. Demographics and behaviour of 131 IDU were compared with 335 individuals, of whom 112 were gay/bisexual [24 of whom also had sexually transmitted diseases (STD)] and 223 heterosexuals who had STD. Males enrolled were significantly older than females. Multivariate analysis showed that factors independently associated with IDU were: a younger age, less education, mental health counselling, unemployment, and a history of jaundice or hepatitis. Drugs most commonly used were Ritalin/Talwin, cocaine, and heroin. Over 90% of individuals admitted to sharing needles. In spite of the low seroprevalence of HIV-1 infections, these individuals are important for the potential spread of HIV because of multiple means of acquiring and transmitting HIV and a high rate of needle sharing.