The present study aimed to analyze the behavior of different activated carbons in the adsorption and removal of bisphenol A (2-2-bis-4-hydroxypheniyl propane) from aqueous solutions in order to identify the parameters that determine this process. Two commercial activated carbons and one prepared in our laboratory from almond shells were used; they were texturally and chemically characterized, obtaining the surface area, pore size distribution, mineral matter content, elemental analysis, oxygen surface groups, and pH of the point of zero charge (pH(PZC)), among other parameters. Adsorption isotherms of bisphenol A and adsorption capacities were obtained. The capacity of the carbons to remove bisphenol A was related to their characteristics. Thus, the adsorption of bisphenol A on activated carbon fundamentally depends on the chemical nature of the carbon surface and the pH of the solution. The most favorable experimental conditions for this process are those in which the net charge density of the carbon is zero and the bisphenol A is in molecular form. Under these conditions, the adsorbent-adsorbate interactions that govern the adsorption mechanism are enhanced. Influences of the mineral matter present in the carbon samples and the solution chemistry (pH and ionic strength) were also analyzed. The presence of mineral matter in carbons reduces their adsorption capacity because of the hydrophilic nature of the matter. The presence of electrolytes in the solution favor the adsorption process because of the screening effect produced between the positively charged carbon surface and the bisphenol A molecules, with a resulting increase in adsorbent-adsorbate interactions.

Rats given a low-fibre diet based on boiled white rice developed symptoms of severe vitamin K deficiency within 23 d. Inclusion of autoclaved black-eye beans ( Vigna unguiculatu) in the diet prevented the bleeding syndrome. To test the hypothesis that deficiency resulted from low phylloquinone intake exacerbated by inadequate production of menaquinones by the enteric bacteria, a follow-up experiment was carried out in which groups of rats were given an all-rice diet, a rice+beans diet or a stock diet. Rats on the allrice diet had significantly lower faecal concentrations of the main menaquinone-producing bacterial species (Bacteroidesfragilis and Bacteroides vulgutus) than animals on either of the other two diets. This coupled with the much lower faecal output on this diet suggests that total menaquinone production was low for the all-rice diet. The alterations in faecal flora were associated with several significant changes in caecal metabolism. Rats given the stock diet had much shorter caecal transit times and a considerably greater proportion of butyric acid in volatile fatty acid end-products than did rats on either of the other two diets.

A case is reported of a patient with a lentiginous acral melanoma of the heel that was excised and recurred 3 years later at the margin of the previous scar. After another 3 years, a group of five small lesions appeared in the thigh that were considered to be junctional and epidermotropic metastases. The authors question the current histologic criteria for differentiating junctional and epidermotropic metastases of previous melanomas from multiple primary melanomas. It is concluded that the clinical history is of primary importance in reaching a correct diagnosis; histologic studies are not sufficient.

WE have postulated that bacteria may play a vital role in the aetiology of cancer of the colon (Aries et al., 1969; Hill et al., 1971) by producing a carcinogen or co-carcinogen from dietary components or from intestinal secretions. Our work has concentrated on the possibility that gut bacteria might produce such an agent, possibly a polycyclic aromatic hydrocarbon, from the bile acids; this would theoretically require only four types of nuclear dehydrogenation (NDH) reaction (Hill, 1970) and we have now demonstrated all four with human gut bacteria (Aries, Goddard and Hill, 1971 ; Hill, 1972, 1973). Of these, the 6-7 dehydration reaction-which is a manifestation of the 7~-dehydroxylation reaction-is carried out by non-sporing strictly anaerobic bacteria ; the other three reactions have been demonstrated in preliminary studies with lecithinase-negative clostridia.In the work described in the present paper we have extended our screening studies and have demonstrated that the three latter nuclear dehydrogenations (figure) are carried out by a small proportion of strains of Clostridium welchii, a high proportion of strains of C. paraputrzjicum and closely related strains, but by no organisms of various other genera tested. MATERIALS AND METHODS Bacteriological proceduresAll strains tested in our screening studies were isolated by the methods of Drasar and Crowther (1970) from British and American samples of faeces unless otherwise stated. The non-sporing strictly anaerobic organisms were characterised by the methods of Peach et al. (1974). Clostridia were characterised by a method based on that described by Holdeman and Moore (1972); these methods will be fully described by Drasar et al. (1976). The aerobic organisms (Escherichia coli and Streptococcus faecalis) were identified by the methods of Cowan and Steel (1965). Assay of nuclear dehydrogenasesThe assay of cholanoyl fb-dehydrogenase (reaction A) was described by Aries et al. (1971) with 5/3-androstan-3,17-dione as the substrate. The aromatisation of ring A of dandrosten-3,17-dione (reaction B) was assayed by the method described by Goddard and Hill (1972). The formation of equilenin (reaction C) was assayed by the method of Goddard and Hill (1973) based on that of Sehgal and Vezina (1970).

DIET has long been assumed to be one of the major determinants of the faecal flora (Dudgeon, 1926). Studies with experimental animals provide support for this hypothesis (Smith, 1965); however, studies with human faeces have provided less satisfactory evidence (Moore, Cat0 and Holdeman 1969).In a study of faecal specimens from different dietary groups in various parts of the world, we demonstrated differences in the numbers of bacteroides organisms present in faeces (Hill et al., 1971). In the present paper we report on the more detailed classification of the non-sporing anaerobes isolated in that study and during subsequent extensions of the study. MATERIALS AND METHODSSource of faeces. Stool samples were obtained from groups of people consuming a mixed western diet, in England, Scotland and the USA, and from people living on diets with a high carbohydrate content in India, Uganda and Japan. The characteristics of these groups are shown in table I. The groups contained both men and women. All were healthy individuals, mostly aged between 20 and 50. Samples from the USA came from both black and white persons.Transport and storage of specimens. Fresh samples of faeces were diluted 1 in 10 in 10% glycerol broth and immediately frozen in solid carbon dioxide or in liquid nitrogen for transport to London (Crowther, 1971). The samples were stored at -50°C.Isolation of non-sporing anaerobic bacteria. Isolation plates were seeded in an anaerobic cabinet. During the initial stages of this investigation a rigid Perspex cabinet filled with oxygen-free nitrogen (N2) containing 5% carbon dioxide (C02) was employed (Drasar, 1967). Later studies were carried out in a flexible polyvinyl cabinet filled with 5% C02 in a mixture of 90% N2 and 10% hydrogen (H2) (Aranki et al., 1969). Ten-fold dilutions of the specimens were prepared in Brain-Heart-Infusion (BHI) broth (Oxoid) containing 0.05% (w/v) cysteine hydrochloride and 0.03% sodium formaldehyde sulphoxylate as reducing agents. The diluent was heated to 100°C before being introduced into the cabinet, where it was dispensed and allowed to cool in the anaerobic environment. 0.1-ml samples of appropriate dilutions were spread on the surface of plates of Reinforced Clostridial Medium (Oxoid) with 1 % glucose (w/v), 1 % liver digest (Panmede, Paines and Byme, Greenford, England) and 10% defibrinated horse blood. In order to maintain the media in a reduced state, the plates were poured and dried in the Perspex cabinet, or stored for 3 days in the flexible cabinet. Seeded plates were packed into anaerobic jars and on removal from the cabinet the jars were re-evacuated and filled with a gas mixture containing 30% C02 and 70% H2 and incubated at 37°C for 3 days. Cold " D " catalyst was used in the anaerobic jars (Englhard Industries, Cindeford, Gloucestershire).