Compatibility and stability of an admixture of multiple anaesthetic drugs for opioid-free anaesthesia.

The ability to combine and use drugs in a single infusion device may be useful in resource-limited settings. This study examined the chemical stability of an opioid-sparing mixture of ketamine, lidocaine and magnesium sulphate when combined in a single syringe. High-performance liquid chromatography and atomic absorption spectrophotometry were performed on six syringes containing the three-drug mixture. Since most opioid-sparing techniques typically rely on a 24-hour infusion regime, we tested stability at the initial admixing and 24 hours later. Stability was defined as a measured drug concentration within 10% of expected, with the absence of precipitation or pH alterations. Pharmacokinetic simulations were conducted to further show that the achieved plasma drug concentrations were well within an effective analgesic range. All mixed drug concentration measurements were within the required 10% reference limit. No obvious precipitation or interaction occurred, and pH remained stable. Drug stability was maintained for 24 hours. Pharmacokinetic simulations showed that ketamine and lidocaine were within their minimum analgesic effect concentrations. Our results show that this three-drug mixture is chemically stable for up to 24 hours after mixing, with a pharmacokinetic simulation illustrating safe, clinically useful predicted plasma concentrations when using the described admixture.

High frequency in vivo loss of heterozygosity is primarily a consequence of mitotic recombination.

We have used the adenine phosphoribosyltransferase gene (APRT; 16q24) to investigate the mechanisms of loss of heterozygosity (LOH) in normal human somatic cells in vivo. APRT-deficient (APRT-/-, APRT-/0) T lymphocytes from the peripheral blood of four obligate APRT heterozygotes (APRT+/-) with characterized germ-line mutations were selected in medium containing 100 microM 2,6-diaminopurine. A total of 80 2,6-diaminopurine-resistant T-cell clones from 2 of the heterozygotes were analyzed for this study. The presence or absence of LOH of proximal linked microsatellite repeat markers was used to divide the clones into two groups: (a) those in which LOH was likely due to localized changes in APRT (e.g., point mutations); and (b) those with LOH at additional loci. A total of 61 clones (76%) exhibited LOH of linked microsatellite repeat markers at different locations on 16q, which extended from the smallest measured region (<5.5 cM) to the entire 16q arm. The remaining 19 clones (24%) had point mutations in APRT or other relatively minor alterations. Ten clones with LOH encompassing different regions of 16q were examined by conventional cytogenetics and by fluorescence in situ hybridization using an APRT cosmid probe. All clones exhibited a normal diploid karyotype, and nine exhibited two copies of APRT. The one clone that was hemizygous for APRT had the smallest observed region of LOH in clones from that individual. These results indicate that mitotic recombination and, to a much lesser extent, deletion may be the primary mechanisms for the relatively high frequency of in vivo LOH observed in normal human T cells. Because LOH leads to the expression of recessive tumor suppressor genes in many cancers, these data have significant implications for the role of LOH in the early stages of tumor development, especially in breast cancer.

Using e-mail in the management of tuberculosis patients, north-west Russia.

SETTING: Ten health care institutions in north-west Russia. OBJECTIVE: To improve the management of tuberculosis patients using e-mail. DESIGN: Over an 18-month period, all outgoing and incoming e-mails at the Arkhangelsk Regional Tuberculosis Centre were saved and categorised. All e-mails relating to distance learning were logged, and a consensus panel discussed and answered questionnaires regarding 47 e-mail-based second opinions. RESULTS: e-mail was found to speed up communication and increase the availability of specialist advice. Distance learning was positively received, but was used in moderation. For six of 47 consultations (13%), the consensus panel deemed that fast access to a second opinion saved lives. In 30 consultations (64%), the patient was saved a round trip to a specialist centre. In 24 consultations (51%), the panel considered that the patients had started correct treatment between 1 week and 1 month earlier than without e-mail access. In 11 of these consultations, 23% of the total, the patient was found to be infectious. The learning effects of second opinions were recognised. CONCLUSION: General e-mail use and the second opinion service in particular were found to be useful. Further studies are needed to investigate the advantages and disadvantages of using e-mail as a tool in the management of TB.

Aflatoxin B1, 2-aminoanthracene, and 7,12-dimethylbenz[a]anthracene-induced frameshift mutations in human APRT.

Aflatoxin B1, 2-aminoanthracene, and 7,12-dimethylbenz[a]anthracene have been implicated in the etiology of human cancers. In this study, we demonstrate that these three chemicals can be activated by rat liver homogenate S9 coupled with NADPH coenzymes to produce a dose-dependent increase in the frequency of APRT reversion in the APRT-deficient human cell line HTD114. HTD114 contains single nucleotide insertions at different positions in each APRT allele and the spontaneous reversion frequency is < 10(-8). However, the highest reversion frequency induced by these chemicals is 1.2-2.0 x 10(-5), at least a 10(3)-fold increase over the frequency of spontaneous reversion. Reversion of either mutant allele was observed to be a consequence of a frame-restoring loss of a single nucleotide, which indicates that these three chemicals can function as frameshift mutagens in human cells.

An enzyme immunoassay for atractyloside, the nephrotoxin of Callilepis laureola (Impila).

Tubers of Callilepis laureola, a traditional remedy, contain an inhibitor of oxidative phosphorylation; atractyloside. A "competitive" ELISA was developed, using the antiserum produced to an atractyloside-protein conjugate. An ovalbumin-atractyloside conjugate was adsorbed to microtitre wells and plates incubated with sample (atractyloside or tuber extract) and antiserum. After successive incubation with secondary antibody-enzyme conjugate and substrate, the absorbance was read at 405 nm. Antibody working dilution was low, but results, confirmed by thin layer chromatography, indicate the immunoassay has diagnostic potential.

Single-base deletion induced by benzo[a]pyrene diol epoxide at the adenine phosphoribosyltransferase locus in human fibrosarcoma cell lines.

Benzo[a]pyrene diol epoxide (BPDE), a metabolic product of benzo[a]pyrene, is one of the most widely distributed environmental carcinogens. In this study, we demonstrate that BPDE produces a dose-dependent increase in the frequency of APRT gene reversion in the APRT-deficient cell line, HTD114, which contains single nucleotide insertions at different positions in each APRT allele. The highest reversion frequency observed after BPDE exposure was 3.3 +/- 0.9 x 10(-5), at least 10(3)-fold greater than the spontaneous frequency. Reversion of either mutant allele was observed to be a consequence of a frame-restoring loss of a single nucleotide. A similar frequency of BPDE-induced reversion at APRT also was observed in a cell line containing only one type of the mutant alleles of HTD114, thus eliminating the possibility that gene conversion plays a major role in APRT gene reversion in HTD114 cells. Therefore, the data demonstrate that BPDE can function as an effective frameshift mutagen in human cells.

A non-organic and non-enzymatic extraction method gives higher yields of genomic DNA from whole-blood samples than do nine other methods tested.

We compared ten methods for extraction of DNA from whole blood. Nine methods require incubation with either enzymes or treatment of organic solvents or both. The 'Rapid Method' (RM) (Method 10) avoids the use of organic solvents (phenol/chloroform) and eliminates completely the use of proteinase K. Thus, the time and cost of DNA extraction are reduced significantly. This is accomplished by salting out and precipitation of the cellular proteins in saturated sodium chloride. This method takes less than an hour to completion, without compromising the yield or the quality of DNA. Using RM, we can make DNA from 0.1 ml of whole blood and as little as 0.5 ml of blood yields DNA sufficient to run a few Southern blots. The RM can also be applied to packed cells. The DNA is free of RNA, protein and degrading enzymes. The uncut DNA runs as a typical slow-migrating, high-molecular-weight and undegraded species in an agarose gel. The DNA is suitable for digestion by various restriction endonucleases. This procedure works equally well with fresh blood samples and with those that are stored at 4 degrees C and -70 degrees C. To our knowledge the RM reported here is the safest, fastest and most quantitative and economical method for preparation of DNA from whole blood and cells.

The inappropriate use of traditional medicines in South Africa.

Traditional medicines are culturally very important to the Zulu population of Southern Africa. The inappropriate use of herbs has however, resulted in numerous fatalities, invariably in children. This paper briefly summarises the belief of the Zulu population in traditional remedies, together with an outline of the problems at present being experienced in South Africa. A further note on the personal impressions and experiences of the authors and description of one such toxic herbal remedy, including use, toxic action and research carried out to date, are also given.

The isolation of a storage organelle of atractyloside in Callilepis laureola.

A method has been developed for the preparation of protoplasts from both the leaves and tubers of Callilepis laureola, a plant used extensively as a medicament by black people in South Africa. The cellular vacuoles from these protoplasts were isolated and tested for the presence of the nephrotoxic substance, atractyloside, by thin layer chromatography and immunoassay. Both methods indicate that the vacuole of C. laureola is the primary site of storage for atractyloside in the cells of the tuber.

A mobile telemedicine unit for emergency and screening purposes: experience from north-west Russia.

A mobile telemedicine unit (MTU) was constructed for emergency and screening purposes in north-west Russia. The MTU included facilities for endoscopy, electrocardiography and digital photography. Data transmission was by ordinary telephone line. Between July and December 1999, the MTU was used in 48 incidents, involving 44 patients. The MTU was used to conduct 22 teleradiology examinations and 20 electrocardiograms were transmitted; in 10 cases still images of patients were transmitted and three consultations included tele-electroencephalography. Despite poor-quality analogue telephone lines, the MTU may prove useful in north-west Russia. Following the pilot study, the local Russian health administration stated that the MTU should always be included on emergency trips to the districts.

Identification of a 7-basepair deletion in the adenine phosphoribosyltransferase gene as a cause of 2,8-dihydroxyadenine urolithiasis.

We describe a family of Turkish origin with adenine phosphoribosyltransferase (APRT) deficiency and renal stone disease. The proband had 2,8-dihydroxyadenine urolithiasis but an older sister, who was also deficient in enzyme activity, is so far asymptomatic. The proband was homozygous for a 7-bp deletion in exon 3 of the APRT gene. One allele from each of the parents also contained this deletion. The patient and her father were homozygous for an intragenic TaqI RFLP (1.25-kb fragment) whereas the mother was heterozygous (1.25- and 1.91-kb fragments), indicating that the mutation was present on the allele carrying the 1.25 kb TaqI fragment. The deletion alters the reading frame downstream of codon 93 and would be expected to abolish enzyme activity.