Development of a colorimetric colony-screening assay for detection of defluorination by micro-organisms.

AIMS: To develop a colorimetric colony-screening assay to facilitate the isolation of micro-organisms capable of defluorination. METHODS AND RESULTS: A metal-dye chelate, zirconium-xylenol orange was used to detect fluoride ions released from a fluorinated substrate through microbial metabolism. Depolymerised zirconium reagent gave the greatest visual contrast for the presence of fluoride compared to more polymerised forms of zirconium reagent. The sensitivity of the assay was greatest when the molar ratio of depolymerised zirconium to xylenol orange was 1:2. Using depolymerised zirconium and xylenol orange (150 and 300 nmol l(-1) respectively), the assay could detect a fluoride application spot (5 mmol l(-1)) containing 50 nmoles of fluoride ions. Most media constituents were well tolerated by the assay, although phosphate ions needed to be restricted to 0.1 g l(-1) and some proteins digest to between 1 and 5 g l(-1). A microbial enrichment culture growing on solidified medium containing 20 mmol l(-1) fluoroacetate was screened using the assay, and defluorinating bacteria belonging to the genus Burkholderia isolated. CONCLUSIONS: A method was developed that is sensitive, rapid and reliable for detecting defluorination by micro-organisms growing on solidified medium. SIGNIFICANCE AND IMPACT OF THE STUDY: This method can be used to facilitate the isolation of micro-organisms capable of defluorination.

Disaccharidase activities and fat assimilation in pediatric patients after intestinal transplantation.

BACKGROUND: Intestinal transplantation has become an accepted therapy for short bowel syndrome and other types of intestinal failure. In order to assess digestive capabilities and feeding practices in a group of 22 pediatric patients after intestinal transplantation, we assessed mucosal disaccharidase activities and assimilation of total dietary lipid and vitamin E. Twelve of the patients had undergone contemporaneous liver transplantation. METHODS: Mucosal biopsies were assayed for disaccharidase activities between 15 and 412 days after transplantation in 7 of the 22 when all were receiving some enteral nutrition and were free of rejection. Coefficients of lipid absorption were determined in those patients receiving total enteral feeding (two-thirds polymeric/one-third elemental) between 43 and 1032 days after transplantation; oral vitamin E tolerance tests were done at about the same time. RESULTS: Activities of lactase, sucrase, maltase, and palatinase consistently exceeded reference ranges (P<0.05). Mean coefficient of lipid absorption equaled 86+/-12% and was not influenced by duration of time after transplantation. No patient required dietary lipid restriction. No significant absorption of vitamin E was demonstrated until 160 days after transplantation. Vitamin E absorption did correlate with length of time elapsed after surgery (r=0.64, P<0.0011). CONCLUSIONS: The results of this investigation show that, in the absence of histologic or clinical indications of allograft rejection, pediatric intestinal transplant recipients do not have primary disaccharidase deficiencies. Similarly, absorption of usual dietary lipid content is adequate once weaning from parenteral nutrition is complete. In contrast, early assimilation of vitamin E is poor. Vitamin E absorption subsequently improves, but the mechanism is obscure.

Emu oil(s): a source of non-toxic transdermal anti-inflammatory agents in aboriginal medicine.

The 'oil' obtained from emu fat can be a very effective inhibitor of chronic inflammation in rats when applied dermally (with a skin penetration enhancer). Assays for this activity using the adjuvant-induced arthritis model have shown: i. Considerable variability in potency of some commercial oil samples; ii. Little or no correlation of activity with colour or linolenic acid (18:3) content of the oil; iii. Relative stability of some active oils (to heat, ageing at room temperature); iv. The bulk of the anti-inflammatory activity was present in a low triglyceride fraction; and v. Potential arthritis-suppressant/immunoregulant activity of these active fractions. These studies point to the need for more rigid quality control before considering such a (now proven) traditional medicine as a complementary therapy.Repeated applications of selected oils did not induce any of the more prominent side-effects associated with NSAIDs (e.g. platelet inhibition, gastrotoxicity) or certain anti-arthritic drugs (proteinuria, leukopenia).

Calibration of albumin-fatty acid binding constants measured by heptane-water partition.

Most measurements of binding affinity of albumin for long-chain fatty acids are based on heptane-water partition. In this method, equilibrium partition of fatty acid between heptane and an albumin-containing buffer is calibrated using the partition ratio between heptane and buffer in the absence of protein. In the current study, we used a variety of techniques to examine potential problems with this approach. Hydrophobic impurities in commercial [3H]palmitate preparations were incompletely removed by standard purification techniques. These impurities contributed from 5% of the total radioactivity in the heptane phase at low albumin concentrations (5 microM) to 62% at higher albumin concentrations (500 microM), thus confounding determination of binding affinity. These were identified by gas chromatography/mass spectroscopy as radio-labeled glycerol monopalmitate and monostearate. When albumin was not present, the partition ratio was similar to values reported by others. However, our results varied by a factor of four (265-1,119) depending on how the solutions were prepared. Although a true equilibrium partition must not depend on starting conditions, the partition ratio after 24-72 h was > 2x as large when tracer [3H]palmitate was added to the heptane phase than when it was added to the aqueous phase. Results also depended on the relative volumes of heptane and buffer used, approaching a maximum of 1,445 +/- 112 for very low heptane/buffer volume ratios. Much of this variability was due to hydrophilic impurities in [3H]palmitate, which ranged from 0.2 to 1.2% in commercial lots down to 0.1-0.5% after alkaline ethanol extraction and < 0.05% after thin-layer chromatography (TLC).(ABSTRACT TRUNCATED AT 250 WORDS)

Deemed status for CHAP. A new standard for health care.

The board chair of the Community Health Accreditation Program (CHAP) reflects on the implications of federal recognition of CHAP. In challenging the status quo, CHAP has shown that a voluntary, consumer-based alternative can protect the public and promote excellence.

Uptake of palmitate by hepatocyte suspensions: facilitation by albumin?

Albumin-dependent uptake of unbound [3H]palmitic acid by hepatocytes isolated from female rat livers was studied and the experimental results compared with the predictions of a noncompartmental diffusion-reaction theory for the cellular uptake of protein-bound ligands. The outright theoretical predictions involve values for the parameters of the system, some newly measured (hepatocyte radii and the rate constant for the dissociation of palmitate-albumin complex) and some taken from the literature (diffusion coefficients and the equilibrium association constant for the palmitate-albumin complex). The measured unbound clearance of [3H]palmitic acid, defined as the initial uptake velocity divided by the unbound [3H]palmitic acid concentration in the medium, was enhanced 6.6-fold as the concentration of human serum albumin was increased from approximately 5 to 480 microM. This enhancement factor was predicted by the theory, according to which the enhancement reflects codiffusion of bound ligand across the unstirred layer adjacent to the cell membrane and, therefore, an increased delivery of unbound ligand to the cell surface. In contrast, the absolute magnitude of the unbound clearance was consistent with the theory only for the lowest published value for the equilibrium association constant, 15 microM-1. For higher published values (62 and 94 microM-1), the magnitude of the unbound clearance observed experimentally was severalfold higher than that predicted by the theory. If in fact the association constant exceeds 30 microM-1, the data would imply that an albumin-dependent facilitation mechanism exists which enhances the availability of palmitate to the cell over and above the enhancement predicted by the diffusion-reaction theory.

1991 outlook: progress will require partnerships, improved productivity--roundtable discussion.

To address the myriad problems and challenges in the next year, the operative word will be partnership. That's according to members of Modern Healthcare's editorial advisory board in their discussion of the healthcare industry in 1991. The experts see the need for hospitals, physicians and the business community to team up to control costs, solve staffing woes and take initial steps toward healthcare reform.