Sensitive method for detecting low numbers of verotoxin-producing Escherichia coli in mixed cultures by use of colony sweeps and polymyxin extraction of verotoxin

High titers of Verotoxin (VT) were released from cell pellets of VT-producing Escherichia coli (VTEC; corresponding to E. coli strains producing "high" levels of Shiga-like toxin) after incubation in polymyxin B (0.1 mg/ml) for 30 min at 37 degrees C. Maximal titers of polymyxin-releasable VT occurred in cells obtained from 5-h Penassay broth cultures and were up to eightfold higher than the peak culture supernatant VT titers which occurred in 8-h cultures. Polymyxin-releasable cell extracts of 5-h broth cultures inoculated with mixtures of VT-positive (VT+) and VT-negative strains had easily detectable VT titers when the proportion of VT+ cells in the mixture was about 1.0%, but culture supernatants were negative for VT even when this proportion was 20%. The results were the same whether the initial inoculum consisted of broth culture mixtures of VT+ and VT-negative strains or colony sweeps (loopfuls of confluent bacterial growth) taken from solid plate media previously inoculated with the broth mixtures. In a clinical study, 80 stool cultures from patients with hemolytic uremic syndrome and family contacts with diarrhea were tested for free fecal VT, VT in polymyxin extracts of colony sweeps (VT/PECS), and VTEC (examination of 20 separate E. coli colonies from primary media for VT production). Of the 80 samples, 40 were positive for at least one of these three tests; all 40 were positive for free fecal VT, and 20 of these were positive for VT/PECS. VTEC (as few as 1 colony out of 20) were only isolated from 14 of the 20 cultures that were positive for VT/PECS. In six cases, the VT/PECS was positive even when none of 20 colonies tested were VT+, suggesting that the procedure was able to detect a proportion of VTEC that was less than one in 20(5%). We conclude that the VT/PECS method is highly sensitive for detecting low concentrations of VTEC in stools and provides a rapid method for screening out stools that are negative for VTEC. The technique should also be of value in epidemiological studies for detecting low numbers of VTEC in animal feces, foods, and environmental samples.

The association between idiopathic hemolytic uremic syndrome and infection by verotoxin-producing Escherichia coli

Forty pediatric patients with idiopathic hemolytic uremic syndrome (HUS) were investigated for evidence of infection by Verotoxin-producing Escherichia coli (VTEC). Fecal VTEC (belonging to at least six different O serogroups including O26, O111, O113, O121, O145, and O157) or specifically neutralizable free-fecal Verotoxin (VT) or both were detected in 24 (60%) patients but were not detected in 40 matched controls. Ten of 15 of the former developed fourfold or greater rises in VT-neutralizing antibody titers, as did six other patients who were negative for both fecal VTEC and VT. A total of 30 (75%) patients had evidence of VTEC infection by one or more criteria. We concluded that a significant association exists between idiopathic HUS and infection by VTEC. The detection of free-fecal VT was the most important procedure for the early diagnosis of this infection because, in our study, VTEC were never isolated in the absence of fecal VT, whereas fecal VT was often present even when VTEC were undetectable.

Maternal-child hepatitis B virus transmission in Singapore

A study of maternal-infant transmission of hepatitis B virus (HBV) was conducted in Singapore between June 1980 and June 1982. HBsAg carrier rate was highest among Chinese (6.2%) followed by Malay (2.3%) and Indian (0.6%) mothers. The presence of HBeAg in maternal sera correlated well with high titre HBsAg (p = 7.34 X 10(-5)). Overall HBV transmission occurred in 27/56 (48.2%) infants from carrier mothers. The majority of the transmission was perinatal. There was a very strong correlation between transmission and HBeAg status of the mother (p = 1.85 X 10(-9); odds ratio = 68.44) and to a lesser extent with high titre HBsAg (p = 0.002; odds ratio = 6.38). A strong negative correlation was seen between transmission and anti-HBeAg (p = 8.19 X 10(-7); odds ratio = 0.04). At one year 19 (70.4%) infants were still HBsAg positive while seven (25.9%) lost the antigenemia and acquired anti-HBsAg and one developed HBsAg after one year. It could be calculated that perinatal HBV transmission contributed about 18% to the total pool of HBsAg positive infants of one year of age.

Rice millers' syndrome: a preliminary report

A study was carried out to determine the health effects of rice husk dust in Malaysian rice millers. The study population consisted of 122 male Malay workers from three rice mills, with 42 controls of similar age, sex, ethnic group, and agricultural work background. Interviews using standardised questionnaires, physical examination, total and differential white cell counts, chest radiographs, and lung function tests were performed on each of the millers and the controls. Environmental dust monitoring was also carried out in the three rice mills. Clinical, haematological, and radiological findings suggest that a distinct clinical syndrome seems to be associated with exposure to rice husk dust. The manifestations of this "rice millers' syndrome" include acute and chronic irritant effects affecting the eyes, skin, and upper respiratory tract; allergic responses such as nasal catarrh, tightness of chest, asthma, and eosinophilia; and radiological opacities in the chest, probably representing early silicosis or extrinsic allergic alveolitis.

An investigation into the response of subjects to a plaque control programme as influenced by friends and relatives

The aim of the present study was to assess the response of patients to a course of instruction in plaque control as influenced by friends and relatives. The subjects in the study were 41 patients who had been referred to a dental hospital for treatment. There was a major reduction in plaque and gingivitis levels in the subjects at both the 10th and 14th weeks of the study. There was a greater proportional reduction in gingivitis levels in those subjects who had a higher number of reported discussions with their friends. The effect of discussions with members of the family was less clear. Lower values for gingivitis levels at 10 weeks were associated with a higher number of discussions with parents. However the levels of gingivitis tended to be adversely affected by discussions between the subjects and their spouses. The importance of recognising the influence of family and friendship networks needs to be understood when preventive programmes are designed, especially where high levels of self-care are sought as outcomes. Further work is in progress on a group of office workers being treated in a dental practice environment. This will allow the type of advice being obtained from the various contacts to be investigated in more detail.

Sporadic cases of haemolytic-uraemic syndrome associated with faecal cytotoxin and cytotoxin-producing Escherichia coli in stools

A cytotoxin active on Vero cells, less active on hela cells, and inactive on WI38 cells (Vero toxin [VT]) was detected in stool isolates of Escherichia coli from 8 of 15 sporadic cases of haemolytic uraemic syndrome (HUS). Stools from 5 of these 8 patients were examined for faecal VT activity, and all were positive. Of the 7 of 15 patients who did not have VT+ E. coli, 2 were positive for faecal VT, and a third (patient K) had strong serological evidence of VT+ E. coli infection. 2 HUS patients, including patient F, had siblings with uncomplicated diarrhoea who had both VT+ E. coli in the stools and faecal VT activity. Thus 11 of 15 (73%) of the HUS cases had evidence of infection by VT+ E. coli, suggesting that there was an association between these organisms and these cases of HUS. The clustering of 2 HUS patients and their siblings with VT+ E. coli accords with this suggestion, as do the rising titres of VT-neutralising antibody in 2 HUS patients.

On the formation of ethoxy alcohols from reaction of trans-1,2-Epoxy-3-methyl-1,3-diphenylbutane and 1,2-Epoxyoctane with boron trifluoride etherate

Reaction of trans-1,2-epoxy-3-methyl-1,3-diphenylbutane (1) with boron trifluoride etherate in benzene gave 3-methyl-2,3-diphenylbutanal (3), shown by deuterium labelling experiments to be formed by C1-O cleavage and alkyl migration, and (1RS,2RS)-l-ethoxy-3-methyl-1,3-diphenyl- butan-2-ol (16) in a process involving retention of configuration at Cl. In ether as solvent the epoxide gave, in addition to aldehyde (3) and ethoxy alcohol (16), 3-methyl-1,3-diphenylbutan-2-one (11) and vinyl ethers (19) and (20). Reaction of 1,2-epoxyoctane (17a) with boron trifluoride etherate in ether gave 1-ethoxyoctan-2-ol (18a) shown by deuterium labelling experiments to be formed by inversion of configuration at C1. The mechanistic implications of these results are discussed.

Eliminations promoted by weak bases. IX. Stereochemistry of olefin formation from trans-2-Phenylcyclopentyl p-bromobenzenesulfonate promoted by lithium chloride in acetone

Parker, Winstein, and their coworkers have previously established that in the E2C elimination of trans-2-phenylcyclopentyl p-bromobenzenesulfonate induced by Bu4NCl in acetone some 9% of the olefinic product is produced by a syn-elimination. In view of the current idea that syn-eliminations in solution are assisted by association of the base with its counterion, the stereochemistry of the reaction induced by lithium chloride in acetone has been studied. There is no increase in the amount of syn-elimination, and kinetic analysis reveals that lithium chloride ion pairs are completely unreactive. 1-Phenylcyclopentene is not produced by rate-limiting attack of chloride ion on a preformed symmetrical phenonium ion pair. These results do not serve to distinguish between two alternative models of the E2C transition state.

[Study of cellular immunity using Rebuck's skin-window (author's transl)]

Value of a modification of Rebuck's skin-window in cellular immunity studies. The mononuclear/polynuclear ratio is determined at given time-intervals. The increase in the number of macrophages as well as their kinetics can be pictured on a diagram, comparatively to the corresponding results in controls. This test appears to provide a means of assessing the activity of a malignant disorder.

Pathology of the vitamin C deficiency syndrome in channel catfish (Ictalurus punctatus)

Channel catfish fingerlings fed purified diets devoid of vitamin C showed reduced growth rate, deformed spinal columns, external and internal hemorrhages, erosion of fins, dark skin color and reduced bone collagen content after 8 to 12 weeks, whereas fish fed a diet containing 30 mg/kg of vitamin C had none of these anomalies after 22 weeks. A dietary level of 30 mg of vitamin C per kg was insufficient to prevent distortion of gill filament cartilage, although 60 mg of vitamin C per kg was sufficient. Vertebral collagen percentages of 25 or below and liver ascorbic acid levels of 30 microgram/g or below appeared to be indicative of vitamin C deficiency in channel catfish fingerlings. Epidermis and dermis were almost completely healed and extensive collagen fiber formation had commenced in the somatic muscle, in experimentally inflicted wounds after 10 days in fish fed the vitamin C-free diet. Skin and muscle at the wound site were almost regenerated to normal after 10 days in fish fed 60 mg of vitamin C per kg of diet.

Rearrangements of ethylene oxide derivatives. Stereoselectivity of the prochiral C1 hydrogens in the boron trifluoride catalysed rearrangement of 1,2-epoxyoctane

The boron trifluoride catalysed rearrangement of 1,2-epoxyoctane to give octanal proceeds by selective (c. 1.4 : 1) migration of the prochiral hydrogen trans to the alkyl group.