D-Serine-induced nephrotoxicity: a HPLC-TOF/MS-based metabonomics approach

HPLC-MS-based metabonomic analysis was used to investigate urinary metabolic perturbations associated with D-serine-induced nephrotoxicity. D-Serine causes selective necrosis of the proximal straight tubules in the rat kidney accompanied by aminoaciduria, proteinuria and glucosuria. Alderely Park (Wistar-derived) rats were dosed with either D-serine (250 mg/kg ip) or vehicle (deionised water) and urine was collected at 0-12, 12-24, 24-36 and 36-48 h post-dosing. Samples were analysed using a Waters Alliance HT 2795 HPLC system coupled to a Waters Micromass Q-ToF-micro equipped with an electrospray source operating in either positive or negative ion mode. Changes to the urinary profile were detected at all time points compared to control. In negative ion mode, increases were observed in serine (m/z=103.0077), m/z=104.0376 (proposed to be hydroxypyruvate) and glycerate (m/z=105.0215), the latter being metabolites of D-serine. Furthermore, an increase in tryptophan, phenylalanine and lactate and decreases in methylsuccinic acid and sebacic acid were observed. Positive ion analysis revealed a decrease in xanthurenic acid, which has previously been assigned and reported using HPLC-MS following exposure to mercuric chloride and cyclosporine A. A general aminoaciduria, including proline, methionine, leucine, tyrosine and valine was also observed as well as an increase in acetyl carnitine. Investigation of additional metabolites altered as a result of exposure to D-serine is on-going. Thus, HPLC-MS-based metabonomic analysis has provided information concerning the mechanism of D-serine-induced renal injury.

Sodium benzoate attenuates D-serine induced nephrotoxicity in the rat

D-Serine causes selective necrosis to the straight portion of the rat renal proximal tubules. The onset is rapid, occurring within 3-4 h and accompanied by proteinuria, glucosuria and aminoaciduria. The metabolism of D-serine by D-amino acid oxidase (D-AAO) may be involved in the mechanism of toxicity. D-AAO is localized within the peroxisomes of renal tubular epithelial cells, which is also the location of D-serine reabsorption. To address the role of D-AAO in D-serine-induced nephrotoxicity, we have examined the effect of sodium benzoate (SB) on the renal injury. SB has been shown to be a potent, competitive inhibitor of kidney D-AAO in vitro. Male Alderley Park rats were exposed to D-serine (500 mg/kg i.p.) 1 h after exposure to SB (125, 250, 500 or 750 mg/kg i.p.). Urine was collected for 0-6 h, then terminal plasma samples and kidneys were taken at 6.5 h. A second group of animals was given SB (500 mg/kg) followed by D-serine (500 mg/kg i.p.; 1 h later) and urine was collected after 0-6, 6-24 and 24-48 h. Terminal plasma samples and kidneys were taken at 48 h. 1H NMR spectroscopic analysis of urine, combined with principal component analysis, demonstrated that SB was able to prevent D-serine-induced perturbations to the urinary profile in a dose dependent manner. This was confirmed by measurement of plasma creatinine and urinary glucose and protein and histopathological examination of the kidneys. Assessment 48 h after D-serine administration revealed that nephrotoxicity was observed in animals pre-treated with SB (500 mg/kg) although the extent of injury was less pronounced than following D-serine alone. These results demonstrate that whilst prior exposure to SB prevents the initial onset of D-serine-induced nephrotoxicity, renal injury is still apparent at later time points. D-AAO activity in the kidney was decreased by 50% 1 h after dosing with SB suggesting that inhibition of this enzyme may be responsible for the observed protection.

The metabonomics of aging and development in the rat: an investigation into the effect of age on the profile of endogenous metabolites in the urine of male rats using 1H NMR and HPLC-TOF MS

The effect of aging and development in male Wistar-derived rats on the profile of endogenous metabolites excreted in the urine was investigated using both (1)H NMR spectroscopy and HPLC-TOF MS using electrospray ionisation (ESI). The endogenous metabolites were profiled in samples collected from male rats every two weeks from just after weaning at 4 weeks up to 20 weeks of age. Multivariate data analysis enabled clusters to be visualised within the data according to age, with urine collected at 4 and 6 weeks showing the greatest differences by both analytical techniques. Markers detected by (1)H NMR spectroscopy included creatinine, taurine, hippurate and resonances associated with amino acids/fatty acids, which increased with age, whilst citrate and resonances resulting from glucose/myoinositol declined. A number of ions were detected by HPLC-MS that were only present in urine samples at 4 weeks of age in both positive and negative ESI, with a range of ions, including e.g. carnitine, increasing with age. Age predictions by PLS-regression modelling demonstrated an age-related trend within these data, between 4 and 12 weeks for HPLC-MS and 4-16 weeks for NMR. The possible utility of these techniques for metabonomic investigations of age-related changes in the rat is discussed and the importance of employing suitable control animals in pharmacological and toxicological studies is highlighted.

D-serine-induced nephrotoxicity: possible interaction with tyrosine metabolism

D-serine selectively damages renal proximal tubule cells in rats by a mechanism that is not fully understood. Recent proteomic analysis identified that D-serine elevated plasma fumarylacetoacetate hydrolase (FAH). FAH is involved in tyrosine catabolism; hence, this pathway may be involved in mediating the toxicity. This work examines whether 2-(2-nitro-4-trifluoromethylbenzoyl)-cyclohexane-1,3-dione (NTBC), a potent inhibitor of the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD) located upstream of FAH, modulates D-serine-induced nephrotoxicity. Rats were pretreated with NTBC (0.5 mg/kg p.o.) or corn oil and then 30 min later given either D-serine (250 mg/kg i.p.) or water. Urine was collected every 12 h until termination (48 h) and analysed by 1H NMR spectroscopy and principal component analysis (PCA). Markers of proximal tubule injury were evident in urine following treatment with D-serine and NTBC + D-serine. PCA could not distinguish between these urine samples suggesting that NTBC does not effect the development of nephrotoxicity. Clinical chemistry analysis of urine and terminal plasma samples and histopathological examination of the kidneys confirmed this. NTBC alone caused a marked increase in the excretion of 4-hydroxyphenylpyruvate (HPPA) and 4-hydroxyphenyllactate (HPLA); however, HPPA and HPLA excretion was minimal following NTBC + D-serine. Instead marked tyrosinuria was observed suggesting that D-serine-induced renal damage markedly affects the handling of increased levels of HPPA and HPLA resulting from the inhibition of HPPD.

A Novel Class of HIV-1 Inhibitors that Targets the Viral Envelope and Inhibits CD4 Receptor Binding

BMS-378806 is a prototype of a new class of small molecule HIV-1 inhibitors that blocks viral attachment to cells. This compound exhibits potent inhibitory activity against a panel of HIV-1 laboratory and clinical isolates (M- and T-tropic), selective for HIV-1 and inactive against HIV-2, SIV and a panel of other viruses. BMS-378806 exhibits no significant cytotoxicity and displays many attractive pharmacological properties such as low protein binding, minimal serum effect on anti-HIV-1 potency, good oral bioavailability in animal species and a clean safety profile in initial animal toxicology studies. The compound binds to gp120 and blocks the attachment of the HIV-1 envelope protein to cellular CD4 receptors via a specific and competitive mechanism. BMS-378806 binds directly to gp120 at an approximately 1:1 stoichiometry, with a binding affinity similar to that of soluble CD4. Further confirmation that this class of compounds targets the envelope in infected cells was obtained through the isolation of resistant variants and the mapping of resistance substitutions to the HIV-1 envelope. In particular, two substitutions, M426L and M475I, are situated at or near the CD4 binding pocket of gp120. Recombinant HIV-1 carrying these two substitutions demonstrated significantly reduced susceptibility to inhibition. Using these HIV-1 gp120 resistant variants and gp120/CD4 contact site mutants, the potential BMS-378806 target site was localized to a specific region within the CD4 binding pocket of gp120. Together, the data show that BMS-378806 is the first of a new class of HIV inhibitors with the potential to become a valued addition to our current repertoire of antiretroviral drugs.

Spectrum of CLN6 mutations in variant late infantile neuronal ceroid lipofuscinosis

The neuronal ceroid lipofuscinoses (NCLs) are a group of autosomal recessive neurodegenerative diseases of childhood. CLN6, the gene mutated in variant late infantile NCL (vLINCL), was recently cloned. We report the identification of eight further mutations in CLN6 making a total of 18 reported mutations. These mutations include missense, nonsense, small deletions or insertions, and two splice-site mutations. Ten mutations affect single amino acids, all of which are conserved across vertebrate species. Minor differences in the pattern of disease symptom evolution can be identified. One patient with a more protracted disease progression was a compound heterozygote for a missense mutation and an unidentified mutation. Fifteen CLN6 mutations occur in one or two families only, and families from the same country do not all share the same mutation. Unlike NCLs caused by mutations in CLN1, CLN3, CLN5, and CLN8, there is no major founder mutation in CLN6. However, one mutation (E72X) is significantly more common in patients from Costa Rica than two other mutations present in that same population. In addition, a 1-bp insertion (c.316insC) is associated with families from Pakistan and I154del may be common in Portugal. A group of Roma Gypsy families from the Czech Republic share two disease-associated haplotypes, one of which is also present in a Pakistani family, consistent with the proposed migration of the Roma from the Indian subcontinent 1,000 years ago. All mutations are recorded in the NCL Mutation Database together with their country of origin for use in the development of rapid screening assays to confirm diagnosis and to facilitate carrier testing appropriate to a population.

Geometric phase associated with mode transformations of optical beams bearing orbital angular momentum

We present direct measurements of a new geometric phase acquired by optical beams carrying orbital angular momentum. This phase arises when the transverse mode of a beam is transformed following a closed path in the space of modes. The measurements were done via the interference of two copropagating optical beams that pass through the same interferometer parts but acquire different geometric phases. The method is insensitive to dynamical phases. The magnitude and sign of the measured phases are in excellent agreement with theoretical predictions.

Effect of intestinal microflora on the urinary metabolic profile of rats: a (1)H-nuclear magnetic resonance spectroscopy study

1. Analysis of urine by (1)H-nuclear magnetic resonance (NMR) spectroscopy is used to detect biochemical disturbances predictive of toxicological changes. Recent studies, using (1)H-NMR spectroscopy have suggested that Alderley Park rats can be classified as hippuric acid (HA) or m-(hydroxyphenyl)propionic acid (m-HPPA) excretors. Evidence exists for the role of intestinal microflora in the excretion of aromatic phenolic compounds including HA and m-HPPA. 2. We sought to investigate whether intestinal microflora contribute to the difference in excretion. Urinary HA and m-HPPA levels were monitored to characterize excretion over time. The effect of intestinal microflora on the (1)H-NMR spectrum was also investigated using antibiotics to sterilize the intestine. Finally, the levels of m-HPPA and phenylpropionic acid (a precursor for HA) were analysed in the caecum and colon (entire tissue, including contents). 3. Characterization confirmed the presence of HA and m-HPPA excretors; enquiries revealed that the rats were obtained from two floors within a barriered breeding unit. Housing the rats from the two floors together for 21 days resulted in comparable levels of HA and m-HPPA excretion demonstrating that the profiles are not stable. 4. Following antibiotic treatment, HA and m-HPPA excretion decreased, indicating that intestinal microflora contribute to the excretion of these compounds. Finally, m-HPPA levels were higher in the colon of rats that excreted m-HPPA whilst PPA was increased in the caecum and colon of rats that excreted HA. 5. These results demonstrate that the observed difference in HA/m-HPPA excretion is due to differences in the intestinal microflora.

A quantitative analysis of perineurial cell basement membrane collagen IV, laminin and fibronectin in diabetic and non-diabetic human sural nerve

The thickness of the perineurial cell basement membrane was examined in diabetic and non-diabetic human sural nerve. A significant increase in thickness was found in the diabetic group. The nature of this thickening was investigated using immunohistochemistry and image analysis in order to semi-quantify three of the major intrinsic components of the perineurial cell basement membrane: collagen IV, laminin and fibronectin. Amounts of all three components were shown to be increased in the diabetic group, but not significantly so. However, significant linear correlations between fascicle size and perineurial collagen IV, laminin and fibronectin were identified in both diabetic and non-diabetic nerve.

Degradation of explosives by nitrate ester reductases

Explosive-contaminated land poses a hazard both to the environment and to human health. Microbial enzymes, either in their native or heterologous hosts, are a powerful and low-cost tool for eliminating this environmental hazard. As many explosives have only been present in the environment for 10 years, and with similar molecules not known in Nature, the origin of enzymes specialized for the breakdown of explosives is of particular interest. Screening of environmental isolates resulted in the discovery of flavoproteins capable of denitrating the explosives pentaerythritol tetranitrate (PETN) and glycerol trinitrate. These nitrate ester reductases are related in sequence and structure to Old Yellow Enzyme from Saccharomyces carlsbergenisis. All the members of this family have alpha/beta barrel structures and FMN as a prosthetic group, and reduce various electrophilic substrates. The nitrate ester reductases are, however, unusual in that they display activity towards the highly recalcitrant, aromatic explosive 2,4,6-trinitrotoluene, via a reductive pathway resulting in nitrogen liberation. We have embarked on a detailed study of the structure and mechanism of PETN reductase from a strain of Enterobacter cloacae. Work is focused currently on relating structure and function within this growing family of enzymes, with a view to engineering novel enzymes exhibiting useful characteristics.

The gene mutated in variant late-infantile neuronal ceroid lipofuscinosis (CLN6) and in nclf mutant mice encodes a novel predicted transmembrane protein

The neuronal ceroid lipofuscinoses (NCLs) are a group of autosomal recessive neurodegenerative diseases characterized by the accumulation of autofluorescent lipopigment in various tissues and by progressive cell death in the brain and retina. The gene for variant late-infantile NCL (vLINCL), CLN6, was previously mapped to chromosome 15q21-23 and is predicted to be orthologous to the genes underlying NCL in nclf mice and in South Hampshire and Merino sheep. The gene underlying this disease has been identified with six different mutations found in affected patients and with a 1-bp insertion in the orthologous Cln6 gene in the nclf mouse. CLN6 encodes a novel 311-amino acid protein with seven predicted transmembrane domains, is conserved across vertebrates and has no homologies with proteins of known function. One vLINCL mutation, affecting a conserved amino acid residue within the predicted third hydrophilic loop of the protein, has been identified, suggesting that this domain may play an important functional role.

Glutamine synthetase activity and expression are not affected by the development of motor neuronopathy in the G93A SOD-1/ALS mouse

The expression and activity of the enzyme glutamine synthetase (GS) were examined in the G93A/SOD-1 transgenic mouse model of progressive motor neuronopathy to investigate the mechanisms underlying degeneration of the motor neurones. Clinical signs appeared in G93A/SOD-1 mice at around 90 days, with severe spasticity and loss of self-righting reflex from 120 to 150 days of age. GS expression was examined using western blotting in primary astrocyte cultures derived from newborn (P1-2) G93A/SOD-1 mice and their non-transgenic littermates and in lower spinal cord from animals at 30, 60 and 90 days of age and disease end-stage (120-150 days). There were no differences in the levels of GS expression in the transgenic mice compared to the unaffected littermates at any of the disease stages examined. GS activity was measured spectrophotometrically in spinal cord extracts at these disease stages. There was a decrease in V(max) at 60 days compared to 30 days in both groups of mice (3.48+/-0.58 cf. 6.43+/-1.83 mmol/h/mg protein; non-transgenic littermates), with GS activity highest at end-stage (9.38+/-0.71 mmol/h/mg protein cf. 7.64+/-0.42 mmol/h/mg protein in littermates). Conversely, K(m) was transiently increased at 60 days (2.53+/-0.26 mM cf. 1.32+/-0.20 in littermates), remaining within the range of 30 day measurements from 90 days onwards. There were no differences in V(max) or K(m) values between the G93A/SOD-1 mice and their unaffected non-transgenic littermates at any of the disease stages examined. We conclude that there is no evidence that a change in glutamine synthetase activity or expression contributes to the progressive neurodegeneration observed in the G93A/SOD-1 mice.

Tail-docking alters fly numbers, fly-avoidance behaviors, and cleanliness, but not physiological measures

Tail docking is an animal well-being issue not only regarding the docking procedures but also because of concerns during fly season. To address the latter question, we selected eight cows that had been tail-docked in a previous experiment and eight nondocked cows matched by stage of lactation. Physiological, immunological, and behavioral measures were used to evaluate the well being of those cows housed in a tie-stall barn during fly season for 5 consecutive days. Behavior was observed for 5-min interval instantaneous scan samples for 1 h each at 0800, 1200, and 1600 h. Flies were counted before behavior observations. Blood samples were taken daily for plasma and leukocyte separation. Cows were scored on d 5 for cleanliness on a five-point scale. Docked cows were cleaner, but fly counts of docked cows were greater for total fly counts and rear leg counts. However, counts were not different on front legs. Time of day was significant, so each time of day was analyzed separately. Docked cows were observed to exhibit fewer tail swings at 0800 h, but docked cows tended to ruminate more at that time. Docked cows tended to stand less at the 1200 h observation. Total fly-avoidance behaviors were greater for all cows at the 1600-h observation. Only tail swings tended to be more frequent with docked cows, but foot stomps occurred only in the docked cows. Lymphocyte phenotypes, acute-phase proteins, and immunoglobulin concentrations did not differ. In conclusion, although docked cows were cleaner, as the fly numbers increase throughout the day, fly-avoidance behaviors also increased and foot stomping appeared as an alternative method for fly avoidance by docked cows.

Gluteus medius and rump fat depths as additional live animal ultrasound measurements for predicting retail product and trimmable fat in beef carcasses

This study was conducted to determine the ability of additional ultrasound measures to enhance the prediction accuracy of retail product and trimmable fat yields based on weight and percentage. Thirty-two Hereford-sired steers were ultrasonically measured for 12th-rib fat thickness, longissimus muscle area, rump fat thickness, and gluteus medius depth immediately before slaughter. Chilled carcasses were evaluated for USDA yield grade factors and then fabricated into closely trimmed, boneless subprimals with 0.32 cm s.c. fat. The kilogram weight of end-point product included the weight of trimmed, boneless subprimals plus lean trim weights, chemically adjusted to 20% fat, whereas the fat included the weight of trimmed fat plus the weight of fat in the lean trim. Prediction equations for carcass yield end points were developed using live animal or carcass measurements, and live animal equations were developed including ultrasound ribeye area or using only linear measurements. Multiple regression equations, with and without ultrasound rump fat thickness and gluteus medius depth, had similar R2 values when predicting kilograms of product and percentages of product, suggesting that these alternative variables explained little additional variation. Final unshrunk weight and ultrasound 12th-rib fat thickness explained most of the variation when predicting kilograms of fat. Rump fat and gluteus medius depth accounted for an additional 10% of the variation in kilograms of fat, compared with the equation containing final weight, ultrasound ribeye area, and ultrasound 12th-rib fat thickness; however, the two equations were not significantly different. Prediction equations for the cutability end points had similar R2 values whether live animal ultrasound measurements or actual carcass measurements were used. However, when ultrasound ribeye area was excluded from live animal predictions, lower R2 values were obtained for kilograms of product (0.81 vs 0.67) and percentages of product (0.41 vs 0.17). Conversely, the exclusion of ultrasound ribeye area had little effect on the prediction accuracy for kilograms of fat (0.75 vs 0.74) and percentage fat (0.50 vs 0.40). These data substantiate the ability of live animal ultrasound measures to accurately assess beef carcass composition and suggest that the alternative ultrasound measures, rump fat and gluteus medius depth, improve the accuracy of predicting fat-based carcass yields.

Cultured glial cells are resistant to the effects of motor neurone disease-associated SOD1 mutations

Free radical damage has been implicated in the pathophysiology of motor neurone disease (MND); mutations have been identified in the gene encoding Cu/Zn superoxide dismutase (SOD1). There is evidence that glial cell dysfunction may contribute to motor neurone injury, but the exact role of glial cells in MND has yet to be established. The aim of this study was to determine whether expression of mutant SOD1 affects the response of glia to oxidative stress. Stable C6 glioma cells expressing mutant SOD1 and cortical astrocyte cultures from G93A-SOD1 transgenic mice were exposed to: xanthine/xanthine oxidase; hydrogen peroxide; A23187 and 3-morpholinosydonimine. Cell viability was measured using the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Neither C6 glioma cells nor cortical astrocytes expressing mutant SOD1 were more susceptible to any of the free radical generating systems compared to control cells. These results suggest that astrocytes are resistant to the toxic effects of mutant SOD1 widely reported for neuronal cells.

Empirical and ab initio energy/architectural patterns for 73 nido-6<V>-carborane isomers, from B(6)H(9)(-) to C(4)B(2)H(6)

Qualitative rules governing carbon and bridge-hydrogen placement permit the prediction of the most stable isomeric structures for the various carboranes. Seventy-three isomeric boron hydride and carborane structures, from B(6)H(9)(-) to C(4)B(2)H(6), were computed at the ab initio MP2(fc)/6-31G level to determine their relative stabilities quantitatively. Specific architectural features, recognized to be unfavorable, were assigned "energy penalty" values that allow the projection of comprehensive thermodynamic stability values via a simple additivity procedure. These values match the ab initio results with surprising precision. Our study includes Siebert's nido-2,3,5-C(3)B(3)H(7) and Wrackmeyer's nido-2,4-C(2)B(4)H(8) nido-6<V> carboranes, which contain "unusual" CH-B-bridge hydrogens.

Neuroprotective effects of MK-801 on L-2-chloropropionic acid-induced neurotoxicity

L-2-Chloropropionic acid is selectively toxic to the cerebellum in rats; the granule cell necrosis observed within 48 h can be prevented by prior administration of MK-801. Short-term treatment (2 h) with L-2-chloropropionic acid has also been shown to activate the mitochondrial pyruvate dehydrogenase complex in fasted adult rats. This study aimed to investigate the effect of prior exposure to MK-801 on the biochemical and neurotoxicological effects of L-2-chloropropionic acid. Extracts were prepared from the forebrain and cerebellum of animals that had been treated with L-2-chloropropionic acid, with and without prior treatment with MK-801, and were analysed using magnetic resonance spectroscopy and amino acid analysis. Glucose metabolism was studied by monitoring the metabolism of [1-(13)C]-glucose using GC/MS. L-2-Chloropropionic acid caused increased glucose metabolism in both brain regions 6 h after administration, confirming activation of the pyruvate dehydrogenase complex, which was not prevented by MK-801. After 48 h an increase in lactate and a decrease in N-acetylaspartate was observed only in the cerebellum, whereas phosphocreatine and ATP decreased in both tissues. MK-801 prevented the changes in lactate and N:-acetylaspartate, but not those on the energy state. These studies suggest that L-2-chloropropionic acid-induced neurotoxicity is only partly mediated by the NMDA subtype of glutamate receptor.

MRI studies of the neurotoxic effects of l -2-chloropropionic acid on rat brain

L-2-Chloropropionic acid (L-CPA) is selectively toxic to rat cerebellar granule cells; necrosis is first observed about 36 hours after administration of L-CPA (750 mg/kg p.o.) becoming more marked by 48 h. Parallel to the onset of cell death an increase in cerebellar water content and sodium concentration has been reported suggesting an oedematous reaction. In this study T(2)-weighted (T(2)WI) and diffusion weighted (DWI) imaging were used to detect the development of neuronal damage in the cerebellum of rats as a result of exposure to L-CPA. T(2)WI and DWI were not able to detect cerebellar abnormalities at 37 h post-dosing except for a slight swelling of the cerebellum. However, at 48 h post-dosing when cerebellar swelling and granule cell necrosis were marked, T(2)WI and DWI hyperintensities were observed in the cerebellum. Therefore, under the conditions of this study, MRI was not able to detect abnormalities in the cerebellum prior to the onset of the clinical signs of neurotoxicity or at the time of early histological changes. T(2)WI also suggested a marked increase in the amount of fluid in the ventricular system of rats 37 and 48 h after dosing; fluid accumulation was observed in all animals studied whether or not necrosis was detected. The occurrence of T(2)WI hyperintensity in the forebrain lead us to discover a new lesion in the habenular nucleus.

Turkish variant late infantile neuronal ceroid lipofuscinosis (CLN7) may be allelic to CLN8

One variant form of late infantile neuronal ceroid lipofuscinosis (LINCL) is found predominantly within the Turkish population (CLN7). Exclusion mapping showed that CLN7 was not an allelic variant of known NCL loci (CLN1, CLN2, CLN3, CLN5 or CLN6). Using the method of homozygosity mapping, a genome-wide search was undertaken and a total of 358 microsatellite markers were typed at an average distance of about 10 cM. A region of shared homozygosity was identified on chromosome 8p23. This telomeric region contained the recently identified CLN8 gene. A missense mutation in CLN8 causes progressive epilepsy with mental retardation (EPMR) or Northern epilepsy, which has so far been reported only from Finland and is now classified as an NCL. The mouse model mnd has been shown to carry a 1 bp insertion in the orthologous Cln8 gene. Statistically significant evidence for linkage was obtained in this region, with LOD scores > 3, assuming either homogeneity or heterogeneity. Flanking recombinants defined a critical region of 14 cM between D8S504 and D8S1458 which encompasses CLN8. This suggests that Turkish variant LINCL, despite having an earlier onset and more severe phenotype, may be an allelic variant of Northern epilepsy. However mutation analysis has not so far identified a disease causing mutation within the coding or non-coding exons of CLN8 in the families. The Turkish variant LINCL disease-causing mutation remains to be delineated.

Analysis of candidate genes in the CLN6 critical region using in silico cloning

CLN6, the gene for variant late infantile neuronal ceroid lipofuscinosis, was mapped to a 4 cM region on chromosome 15q22-23. Subsequently the critical region was narrowed to less than 1 cM between microsatellite markers D15S988 and D15S1000 by additional marker typing in an expanded family resource. A physical map was constructed across this region using YAC and PAC clones and sequence was generated from two PAC clones. This sequence was analysed together with overlapping sequence generated by the Human Genome Project to identify genes within the region using an in silico cloning approach. In all, 29 genes have been identified and 18 have been analysed for mutations by direct sequencing. This powerful new approach will lead to the identification of CLN6.

Control of Meloidogyne chitwoodi in Potato with Fumigant and Nonfumigant Nematicides

During 1993-94, several fumigant and nonfumigant nematicides were tested alone and in combination at various rates for control of Columbia root-knot nematode (Meloidogyne chitwoodi) in potato. Ethoprop, oxamyl, or metam sodium alone did not adequately reduce tuber infection. Metam sodium plus ethoprop reduced culled tubers to 3%, and metam sodium plus 2 or 3 foliar applications of oxamyl reduced culls to </=10% in all but one instance. Fosthiazate provided excellent control of tuber infection with or without metam sodium. Rates of 1,3-dichloropropene (1,3-D) below 234 liters/ha did not always adequately control tuber damage, but 140 liters/ha of 1,3-D plus ethoprop reduced the percentage of culled tubers to zero. 1,3-Dichloropropene plus chloropicrin did not provide better control than 1,3-D alone. Combinations of 1,3-D at 94 liters/ha or greater plus metam sodium at 374 liters/ha or greater consistently provided excellent control of tuber damage by M. chitwoodi and would be the treatment of choice where soilborne fungal pathogens are also present.

A prospective study of faecal bile acids and colorectal cancer

A prospective study of 7079 people aged 45-74 recruited through general practices in South Wales, Herefordshire and Edinburgh, Scotland was undertaken to test the hypothesis that faecal bile acids are implicated in the causation of large bowel cancer. The population was recruited between 1974 and 1980 and the response rate for stool collection was 67%. Bile acid analyses were performed on those cases that presented by 1990. It was decided in advance to examine the hypothesis separately for left- and right-sided bowel cancer because of known epidemiological differences between the two sites and to exclude the cases presenting within 2 years of the stool sample from the analyses because the cancer could have been present at recruitment and might have possibly affected faecal bile acid concentrations. Each case (n = 51 left-sided and 8 right-sided) was matched with three controls by age (within 5 years), sex, place of residence and time of providing the stool sample (within 3 months). Statistical analyses using conditional logistic regression showed no significant differences between the left-sided cases and controls for any of the concentrations of individual bile acids, total bile acid concentrations, faecal neutral steroids, percentage bacterial conversion and the ratio of lithocholic acid to deoxycholic acid concentrations. There was a statistically significant (P = 0.021) association of the presence of chenodeoxycholic acid (5/8 samples) in the right-sided cases compared with the controls (3/23), odds ratio 6.26 (95% confidence interval 1.19, 32.84). A high proportion of primary bile acids has also been found in other studies of patients with a genetic predisposition to proximal bowel cancer, however this pattern may also occur in low risk groups, such as Indian vegetarians, suggesting that they may predispose to right-sided bowel cancer only in the presence of other, as yet unknown factors. If bile acids are involved in the causation of large bowel cancer, they may be part of a complex set of interacting factors.

Cloning, sequencing and expression in Escherichia coli of the primary alcohol dehydrogenase gene from Thermoanaerobacter ethanolicus JW200

The structural gene, adhA, for a thermostable primary alcohol dehydrogenase was cloned from Thermoanaerobacter ethanolicus JW200. Constitutive expression from its own promoter was observed in Escherichia coli. The nucleotide sequence of adhA corresponded to an open reading frame of 1197 bp, encoding a polypeptide of 399 amino acids with a calculated Mr of 43 192. Amino acid sequence analysis showed 67-69% identity with alcohol dehydrogenases from two archaeal species and 29-37% identity with bacterial type III alcohol dehydrogenases. This represents the first reported cloning of an alcohol dehydrogenase from a bacterial species that is both thermostable and active against primary long-chain alcohols.