An outbreak of food poisoning suspected to be caused by Vibrio fluvialis.

A small outbreak of gastroenteritis was reported in June 1981 from Arangaon village of Maharashtra State, India. Of the 34 participants who took lunch in a religious ceremony, 14 became suddenly sick 4 to 6 hours after the meal with clinical manifestations of food poisoning. Of the 14 stool samples examined, one from each patient, Vibrio fluvialis was isolated from nine without the growth of any other enteropathogenic bacteria. Although any left-over portions of food were not available for bacteriological examination, the results do suggest that the food, probably contaminated with the organism, was the source of infection in the disease outbreak.

[Enzyme immunoassay for thromboxane B2]. / Enzymimmunoassay für Thromboxan B2.

A sensitive and specific enzyme immunoassay for TXB2, the stable degradation product of thromboxane A2, was developed, in which the hapten molecule was labeled with pure peroxidase. After competitive binding to antibody between enzyme-labeled and free TXB2, the immunoreactive product was precipitated by double antibody technique, and the enzyme activity of the precipitate was determined spectrophotometrically. The procedures allowed a determination of 3-200 pg TXB2/tube (0.081 to 5.4 nmol/l).

An enzyme-linked immunoassay for thromboxane B2 and 6-oxo-PGF1 alpha using peroxidase as label.

A sensitive and specific enzyme immunoassay was developed for TXB2 and 6-oxo-PGF1 alpha, stable degradation products of TXA2 and prostacyclin. The hapten molecule was labeled with pure peroxidase. After competitive binding to antibody between enzyme-labeled and free prostanoids the immunoreactive complex was precipitated by double antibody technique. The enzyme activity of the precipitate was determined spectrophotometrically. The procedure allowed a determination of TXB2 and 6-oxo-PGF1 alpha in the range of 3-200 pg (0.008-0.53 pmol) and 10-1000 pg (0.028-2.8 pmol) respectively.

An improved malondialdehyde assay for estimation of thromboxane synthase activity in washed human blood platelets.

After stimulation of the washed human blood platelets by arachidonic acid (AA), the concurrent evaluations for formed malondialdehyde (MDA) measured by the common photometrical thiobarbituric acid (TBA) method, and for thromboxane B2 (TXB2) measured by gas chromatography, revealed that the formed MDA exceeded the amount of TXB2 on a molar base. However, MDA and TXB2 originating from thromboxane synthase activity should be produced in approximately equimolar amounts. By treatment of the stimulated platelet samples with stannous chloride it is possible to reduce all peroxidized products of AA which generate MDA otherwise during the TBA reaction and to estimate MDA and TXB2 in a ratio of nearly 1:1. The stannous chloride treatment does not destroy the MDA and does not influence the TBA reaction with MDA. Therefore the simple and quick TBA method can be used after stannous chloride treatment for estimation of thromboxane synthase activity in AA stimulated washed human platelets.

Inhibition of prostaglandin I2 (PGI2) formation by LDL-cholesterol or LDL-peroxides?

A hypothesis of Gryglewski et al. explains the correlation between increased level of LDL and development of atherosclerosis by inhibition of PGI2 synthesis by increased peroxide content of LDL. The aim of the present paper was to examine this hypothesis. The major results are: 1) Preparation of LDL in the presence of .02% butylated hydroxytoluene did not reduce the lipid peroxide content of LDL from men and women and not change the inhibition or stimulation of the in vitro biosynthesis of PGI2 by LDL isolated from blood of men or women, respectively. 2) In the LDL and HDL, respectively, of healthy men we found nearly the same lipid peroxide levels (nmole malondialdehyde (MDA)/mg lipoprotein-cholesterol) as in the lipoproteins of male patients with hyperlipidemia type IIa or IV, but the peroxide concentration is three times higher in HDL as in LDL. 3) LDL isolated from healthy men inhibited in dose dependent fashion the generation of PGI2 from PGH2 by aortic microsomes whereas LDL from premenopausal women stimulated PGI2 formation even calculated as LDL lipid peroxides (in nM MDA/ml). The results call into question the hypothesis that diminished PGI2 formation by atherosclerotic vessels is related to inhibition of PGI2 synthetase by lipid peroxides present in LDL in the lesions. A new working hypothesis is presented that also the fatty acid pattern and the lipid class composition in the LDL are important for their influence on the PGI2 formation.

Low density lipoprotein (LDL) from male volunteers stimulated the thromboxane formation by human platelets.

LDL (0.5 - 2.0 mg LDL-cholesterol/ml) isolated from venous blood of healthy male volunteers stimulated dose-dependently the malondialdehyde (MDA) formation by frozen human platelets, used as a marker for the activity of the thromboxane synthetase. HDL (0.25 - 1.0 mg HDL-cholesterol/ml) and human serum albumin (1 - 10 mg/ml) had no concentration-dependent influence on the MDA formation. If these results can be extended to in vivo they suggested the strong connection between the prostaglandin and lipoprotein hypothesis of pathogenesis of atherosclerosis.