Nitrate attenuation in groundwater: a review of biogeochemical controlling processes

Biogeochemical processes controlling nitrate attenuation in aquifers are critically reviewed. An understanding of the fate of nitrate in groundwater is vital for managing risks associated with nitrate pollution, and to safeguard groundwater supplies and groundwater-dependent surface waters. Denitrification is focused upon as the dominant nitrate attenuation process in groundwater. As denitrifying bacteria are essentially ubiquitous in the subsurface, the critical limiting factors are oxygen and electron donor concentration and availability. Variability in other environmental conditions such as nitrate concentration, nutrient availability, pH, temperature, presence of toxins and microbial acclimation appears to be less important, exerting only secondary influences on denitrification rates. Other nitrate depletion mechanisms such as dissimilatory nitrate reduction to ammonium and assimilation of nitrate into microbial biomass are unlikely to be important in most subsurface settings relative to denitrification. Further research is recommended to improve current understanding on the influence of organic carbon, sulphur and iron electron donors, physical restrictions on microbial activity in dual porosity aquifers, influences of environmental condition (e.g. pH in poorly buffered environments and salinity in coastal or salinized soil settings), co-contaminant influences (particularly the contrasting inhibitory and electron donor influences of pesticides) and improved quantification of denitrification rates in the laboratory and field.

mTOR inhibition alleviates mitochondrial disease in a mouse model of Leigh syndrome

Mitochondrial dysfunction contributes to numerous health problems, including neurological and muscular degeneration, cardiomyopathies, cancer, diabetes, and pathologies of aging. Severe mitochondrial defects can result in childhood disorders such as Leigh syndrome, for which there are no effective therapies. We found that rapamycin, a specific inhibitor of the mechanistic target of rapamycin (mTOR) signaling pathway, robustly enhances survival and attenuates disease progression in a mouse model of Leigh syndrome. Administration of rapamycin to these mice, which are deficient in the mitochondrial respiratory chain subunit Ndufs4 [NADH dehydrogenase (ubiquinone) Fe-S protein 4], delays onset of neurological symptoms, reduces neuroinflammation, and prevents brain lesions. Although the precise mechanism of rescue remains to be determined, rapamycin induces a metabolic shift toward amino acid catabolism and away from glycolysis, alleviating the buildup of glycolytic intermediates. This therapeutic strategy may prove relevant for a broad range of mitochondrial diseases.

Cultivation-dependent and -independent approaches for determining bacterial diversity in heavy-metal-contaminated soil

In recent years, culture-independent methods have been used in preference to traditional isolation techniques for microbial community analysis. However, it is questionable whether uncultured organisms from a given sample are important for determining the impact of anthropogenic stress on indigenous communities. To investigate this, soil samples were taken from a site with patchy metal contamination, and the bacterial community structure was assessed with a variety of approaches. There were small differences in microscopic epifluorescence bacterial counts. Denaturing gradient gel electrophoresis (DGGE) profiles of 16S rRNA gene fragments (16S-DGGE) amplified directly from soil samples were highly similar. A clone library generated from the most contaminated sample revealed a diverse bacterial community, which showed similarities to pristine soil communities from other studies. However, the proportion of bacteria from the soil samples that were culturable on standard plate-counting media varied between 0.08 and 2.2%, and these values correlated negatively with metal concentrations. The culturable communities from each sample were compared by 16S-DGGE of plate washes and by fatty acid profiling of individual isolates. Each approach indicated that there were considerable differences between the compositions of the culturable communities from each sample. DGGE bands from both culture-based and culture-independent approaches were sequenced and compared. These data indicated that metal contamination did not have a significant effect on the total genetic diversity present but affected physiological status, so that the number of bacteria capable of responding to laboratory culture and their taxonomic distribution were altered. Thus, it appears that plate counts may be a more appropriate method for determining the effect of heavy metals on soil bacteria than culture-independent approaches.

Mitochondrial complex I deficiency increases protein acetylation and accelerates heart failure

Mitochondrial respiratory dysfunction is linked to the pathogenesis of multiple diseases, including heart failure, but the specific mechanisms for this link remain largely elusive. We modeled the impairment of mitochondrial respiration by the inactivation of the Ndufs4 gene, a protein critical for complex I assembly, in the mouse heart (cKO). Although complex I-supported respiration decreased by >40%, the cKO mice maintained normal cardiac function in vivo and high-energy phosphate content in isolated perfused hearts. However, the cKO mice developed accelerated heart failure after pressure overload or repeated pregnancy. Decreased NAD(+)/NADH ratio by complex I deficiency inhibited Sirt3 activity, leading to an increase in protein acetylation and sensitization of the permeability transition in mitochondria (mPTP). NAD(+) precursor supplementation to cKO mice partially normalized the NAD(+)/NADH ratio, protein acetylation, and mPTP sensitivity. These findings describe a mechanism connecting mitochondrial dysfunction to the susceptibility to diseases and propose a potential therapeutic target.

Corneal confocal microscopy: a non-invasive surrogate of nerve fibre damage and repair in diabetic patients

AIMS/HYPOTHESIS

The accurate detection, characterization and quantification of human diabetic neuropathy are important to define at risk patients, anticipate deterioration, and assess new therapies. Corneal confocal microscopy is a reiterative, rapid, non-invasive in vivo clinical examination technique capable of imaging corneal nerve fibres. The aim of this study was to define the ability of this technique to quantify the extent of degeneration and regeneration of corneal nerve fibres in diabetic patients with increasing neuropathic severity.

METHODS

We scanned the cornea and collected images of Bowman's layer (containing a rich nerve plexus) from 18 diabetic patients and 18 age-matched control subjects.

RESULTS

Corneal nerve fibre density (F(3)=9.6, p<0.0001), length (F(3)=23.8, p<0.0001), and branch density (F(3)=13.9, p<0.0001) were reduced in diabetic patients compared with control subjects, with a tendency for greater reduction in these measures with increasing severity of neuropathy.

CONCLUSION/INTERPRETATION

Corneal confocal microscopy is a rapid, non-invasive in vivo clinical examination technique which accurately defines the extent of corneal nerve damage and repair and acts as a surrogate measure of somatic neuropathy in diabetic patients. It could represent an advance to define the severity of neuropathy and expedite assessment of therapeutic efficacy in clinical trials of human diabetic neuropathy.

Role of transport proteins in drug absorption, distribution and excretion

1. The molecular and functional characterization of transport proteins is emerging rapidly and significant numbers of drugs have been shown to be substrates or inhibitors. The purpose of this review is to highlight the in vivo preclinical and clinical evidence that supports a role for transport proteins in attenuating the absorption, distribution and excretion (ADE) of drugs. 2. For absorption, a clear role has emerged for P-glycoprotein in limiting permeability across the gastrointestinal tract. As a result, a wide variety of drugs suffer from incomplete, variable and non-linear absorption. Similarly, at the blood-brain barrier a range of drugs has limited brain penetration due to P-glycoprotein-mediated efflux, which can limit therapeutic effectiveness of CNS agents. In the liver, transport proteins are present on the sinusoidal membrane that can be the rate-limiting step in hepatic clearance for some drugs. Mechanistic studies clearly suggest a key role and broad substrate specificity for the OATP family of sinusoidal transporters. Mainly ATP-dependent transport proteins such as P-glycoprotein and MRP2 govern active biliary excretion. 3. Drug-drug interactions have been demonstrated involving inhibition or induction of transport proteins. Clinically significant interactions in the gastrointestinal tract and kidney have been observed with inhibitors such as ketoconazole, erythromycin, verapamil, quinidine, probenecid and cimetidine. Clinically significant inhibition at the blood-brain barrier is more difficult to demonstrate, relying on pharmacodynamic and toxicodynamic changes, but an example is quinidine increasing loperamide-induced central effects in humans. 4. This review highlights the emerging role of transport proteins in ADE of drugs and suggests these need to be considered, in drug discovery and development, with respect to variability in drug disposition and response.

Multiple sclerosis: in situ evidence for antibody- and complement-mediated demyelination

We describe a case of multiple sclerosis characterized by deposition of immunoglobulin and complement in the areas of active demyelination. This was particularly evident for the C9neo antigen, which is a marker for the activated lytic complement complex and was exclusively deposited in the areas of active myelin destruction. In addition, macrophages in the lesions contained degradation products that were immunoreactive for myelin antigens, immunoglobulins, and C9neo antigen. Destruction of myelin sheaths was associated with incomplete loss of oligodendrocytes in the active areas and reappearance of oligodendrocytes with remyelination in the inactive plaque center.

Corneal confocal microscopy: a novel noninvasive test to diagnose and stratify the severity of human diabetic neuropathy

OBJECTIVE

The accurate quantification of human diabetic neuropathy is important to define at-risk patients, anticipate deterioration, and assess new therapies.

RESEARCH DESIGN AND METHODS

A total of 101 diabetic patients and 17 age-matched control subjects underwent neurological evaluation, neurophysiology tests, quantitative sensory testing, and evaluation of corneal sensation and corneal nerve morphology using corneal confocal microscopy (CCM).

RESULTS

Corneal sensation decreased significantly (P = 0.0001) with increasing neuropathic severity and correlated with the neuropathy disability score (NDS) (r = 0.441, P < 0.0001). Corneal nerve fiber density (NFD) (P < 0.0001), nerve fiber length (NFL), (P < 0.0001), and nerve branch density (NBD) (P < 0.0001) decreased significantly with increasing neuropathic severity and correlated with NDS (NFD r = -0.475, P < 0.0001; NBD r = -0.511, P < 0.0001; and NFL r = -0.581, P < 0.0001). NBD and NFL demonstrated a significant and progressive reduction with worsening heat pain thresholds (P = 0.01). Receiver operating characteristic curve analysis for the diagnosis of neuropathy (NDS >3) defined an NFD of <27.8/mm(2) with a sensitivity of 0.82 (95% CI 0.68-0.92) and specificity of 0.52 (0.40-0.64) and for detecting patients at risk of foot ulceration (NDS >6) defined a NFD cutoff of <20.8/mm(2) with a sensitivity of 0.71 (0.42-0.92) and specificity of 0.64 (0.54-0.74).

CONCLUSIONS

CCM is a noninvasive clinical technique that may be used to detect early nerve damage and stratify diabetic patients with increasing neuropathic severity.

IL-7 increases both thymic-dependent and thymic-independent T-cell regeneration after bone marrow transplantation

Thymic-dependent differentiation of bone marrow (BM)-derived progenitors and thymic-independent antigen-driven peripheral expansion of mature T cells represent the 2 primary pathways for T-cell regeneration. These pathways are interregulated such that peripheral T-cell expansion is increased in thymectomized versus thymus-bearing hosts after bone marrow transplantation (BMT). This study shows that this interregulation is due to competition between progeny of these 2 pathways because depletion of thymic progeny leads to increased peripheral expansion in thymus-bearing hosts. To test the hypothesis that competition for growth factors modulates the magnitude of antigen-driven peripheral expansion during immune reconstitution in vivo, a variety of T-cell active cytokines were administered after BMT. Of the cytokines (interleukins) tested (IL-3, IL-12, IL-6, IL-2, and IL-7), IL-2 modestly increased peripheral expansion in the face of increasing numbers of thymic emigrants, whereas IL-7 potently accomplished this. This report also demonstrates that the beneficial effect of IL-7 on immune reconstitution is related to both increases in thymopoiesis as well as a direct increase in the magnitude of antigen-driven peripheral expansion. Therefore, the administration of exogenous IL-7, and to a lesser extent IL-2, abrogates the down-regulation in antigen-driven peripheral expansion that occurs in thymus-bearing hosts after BMT. These results suggest that one mechanism by which T-cell-depleted hosts may support antigen-driven T-cell expansion in vivo is via an increased availability of T-cell-active cytokines to support clonal expansion.

Hydrocarbon degradation in soils and methods for soil biotreatment

The cleanup of soils and groundwater contaminated with hydrocarbons is of particular importance in minimizing the environmental impact of petroleum and petroleum products and in preventing contamination of potable water supplies. Consequently, there is a growing industry involved in the treatment of contaminated topsoils, subsoils, and groundwater. The biotreatment methodologies employed for decontamination are designed to enhance in situ degradation by the supply of oxygen, inorganic nutrients, and/or microbial inocula to the contaminated zone. This review considers the fate and effects of hydrocarbon contaminants in terrestrial environments, with particular reference to the factors that limit biodegradation rates. The potential efficiencies, advantages, and disadvantages of biotreatment techniques are discussed and the future research directions necessary for process development are considered.

Randomised controlled trial comparing hospital at home care with inpatient hospital care. I: three month follow up of health outcomes

OBJECTIVES

To compare hospital at home care with inpatient hospital care in terms of patient outcomes.

DESIGN

Randomised controlled trial with three month follow up.

SETTING

District general hospital and catchment area of neighbouring community trust.

SUBJECTS

Patients recovering from hip replacement (n=86), knee replacement (n=86), and hysterectomy (n=238); elderly medical patients (n=96); and patients with chronic obstructive airways disease (n=32).

INTERVENTIONS

Hospital at home care or inpatient hospital care.

MAIN OUTCOME MEASURES

Dartmouth COOP chart to measure patients' general health status; SF-36 to measure possible limitations in physical functioning of patients with hysterectomy; disease specific measures-chronic respiratory disease questionnaire, Barthel index for elderly medical patients, Oxford hip score, and Bristol knee score; hospital readmission and mortality data; carer strain index to measure burden on carers; patients' and carers' preferred form of care.

RESULTS

At follow up, there were no major differences in outcome between hospital at home care and hospital care for any of the patient groups except that those recovering from hip replacement reported a significantly greater improvement in quality of life with hospital at home care (difference in change from baseline value 0.50, 95% confidence interval 0.13 to 0.88). Hospital at home did not seem suitable for patients recovering from a knee replacement, as 14 (30%) of patients allocated to hospital at home remained in hospital. Patients in all groups preferred hospital at home care except those with chronic obstructive airways disease. No differences were detected for carer burden. Carers of patients recovering from knee replacement preferred hospital at home care, while carers of patients recovering from a hysterectomy preferred hospital care.

CONCLUSIONS

Few differences in outcome were detected. Thus, the cost of hospital at home compared with hospital care becomes a primary concern.

Identification of amino acid residues critical for aggregation of human CC chemokines macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and RANTES. Characterization of active disaggregated chemokine variants

Human CC chemokines macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and RANTES (regulated on activation normal T cell expressed) self-associate to form high-molecular mass aggregates. To explore the biological significance of chemokine aggregation, nonaggregating variants were sought. The phenotypes of 105 hMIP-1alpha variants generated by systematic mutagenesis and expression in yeast were determined. hMIP-1alpha residues Asp26 and Glu66 were critical to the self-association process. Substitution at either residue resulted in the formation of essentially homogenous tetramers at 0.5 mg/ml. Substitution of identical or analogous residues in homologous positions in both hMIP-1beta and RANTES demonstrated that they were also critical to aggregation. Our analysis suggests that a single charged residue at either position 26 or 66 is insufficient to support extensive aggregation and that two charged residues must be present. Solution of the three-dimensional NMR structure of hMIP-1alpha has enabled comparison of these residues in hMIP-1beta and RANTES. Aggregated and disaggregated forms of hMIP-1alpha, hMIP-1beta, and RANTES generally have equivalent G-protein-coupled receptor-mediated biological potencies. We have therefore generated novel reagents to evaluate the role of hMIP-1alpha, hMIP-1beta, and RANTES aggregation in vitro and in vivo. The disaggregated chemokines retained their human immunodeficiency virus (HIV) inhibitory activities. Surprisingly, high concentrations of RANTES, but not disaggregated RANTES variants, enhanced infection of cells by both M- and T-tropic HIV isolates/strains. This observation has important implications for potential therapeutic uses of chemokines implying that disaggregated forms may be necessary for safe clinical investigation.

Gait function and decline in adults with cerebral palsy: a systematic review

PURPOSE

The aim of this systematic review was to identify, appraise and synthesize the evidence describing gait decline in adults with cerebral palsy (CP).

METHOD

Comprehensive searches were conducted in MEDLINE (1970-), EMBASE (1980-), CINAHL (1982-) and AMED (1985-) databases to June 2012. Two reviewers independently completed data extraction and analysis using a modified version of the Downs and Black quality tool.

RESULTS

From the 485 papers identified, 16 met the inclusion criteria. Most studies used samples of convenience. The reported mean ages of the study groups varied from 22 to 42.6 years. Decline in gait function was measured variably with the period of decline undefined or from an unknown reference time during childhood. Results suggest that mobility decline occurs in 25% or more of adults with CP. Those at higher risk of gait decline are those with worse initial gait ability, bilateral rather than unilateral motor impairment, older age and higher levels of pain or fatigue.

CONCLUSION

Many ambulant adults with CP experience mobility decline earlier than their nondisabled peers. More information regarding the natural history of mobility change over the lifespan in adults with CP augmented with self-efficacy qualitative data is needed to direct health advice and appropriate interventions for this group.

IMPLICATIONS FOR REHABILITATION

The literature suggests 25% or more of ambulant adults with cerebral palsy experience gait decline. Higher risk of gait decline occurs in those who are older, less independent in gait, have bilateral motor impairment and higher levels of pain or fatigue. Use of standardized gait measurement tools augmented with self-efficacy measures will aid provision of health advice and interventions.

Mitochondrial expression and function of GAS-1 in Caenorhabditis elegans

A mutation in the gene gas-1 alters sensitivity to volatile anesthetics, fecundity, and life span in the nematode Caenorhabditis elegans. gas-1 encodes a close homologue of the 49-kDa iron protein subunit of Complex I of the mitochondrial electron transport chain from bovine heart. gas-1 is widely expressed in the nematode neuromuscular system and in a subcellular pattern consistent with that of a mitochondrial protein. Pharmacological studies indicate that gas-1 functions partially via presynaptic effects. In addition, a mutation in the gas-1 gene profoundly decreases Complex I-dependent metabolism in mitochondria as measured by rates of both oxidative phosphorylation and electron transport. An increase in Complex II-dependent metabolism also is seen in mitochondria from gas-1 animals. There is no apparent alteration in physical structure in mitochondria from gas-1 nematodes compared with those from wild type. These data indicate that gas-1 is the major 49-kDa protein of complex I and that the GAS-1 protein is critical to mitochondrial function in C. elegans. They also reveal the importance of mitochondrial function in determining not only aging and life span, but also anesthetic sensitivity, in this model organism.

Practice distribution in procedural skills training: a randomized controlled trial

BACKGROUND

"Massed" and "distributed" practice are important concepts in the acquisition of fine motor skills, and may be important in training in procedural skills.

METHODS

A total of 41 novice subjects were recruited and randomized to three groups to receive training on the MIST VR surgical trainer. There were 14 subjects in each of groups A and B and 13 subjects in group C. Training comprised 20 min of massed practice for group A, 20 min of distributed practice in 5 min blocks for group B, and 15 min of distributed practice in 5-min blocks for group C. Following the training period, all groups had a 5-min rest period, followed by a 5-min retention test. Comparisons were made between groups A and B, and groups A and C.

RESULTS

There was a statistically significant difference between groups A and B (p = 0.023) on the retention test, with group B performing better. The increment between the groups was 19% for the overall score on MIST VR. There were also significant differences in the time taken to complete the task during the training phase (p = 0.023, training blocks 3 and 4). Graphical representation suggests no effect between groups A and C, and statistical analysis confirms that the observed difference in median score is not significant.

CONCLUSION

This study demonstrates a benefit for distributed practice over massed practice in learning laparoscopic surgical skills on the MIST VR surgical trainer. This finding has potential implications for skills training in all areas of medicine.

Primary structures of locust adipokinetic hormones II

Adipokinetic hormones II from corpora cardiaca of the locusts Schistocerca gregaria and Locusta migratoria, respectively, have been isolated and their primary structures elucidated. Both octapeptides are N-terminally blocked by a 5-oxoproline (pyroglutamate) residue and had to be cleaved by 5-oxoprolyl-peptidase to make them available for the Edman degradation method carried out with a gas-phase sequencer. The C-termini are blocked as both peptides are not cleaved by carboxypeptidase A; the presence of C-terminal amide groups is very likely. AKHII (S. gregaria) Glu-Leu-Asn-Phe-Ser-Thr-Gly-Trp-NH2 AKHII (L. migratoria) Glu-Leu-Asn-Phe-Ser-Ala-Gly-Trp-NH2.

Synthesis and structure-activity relationships of novel naphthalenic and bioisosteric related amidic derivatives as melatonin receptor ligands

A series of N-naphthylethyl amide derivatives were synthesized and evaluated as melatonin receptor ligands. The affinity of each compound for the melatonin receptor was determined by binding studies using [2-125I]iodomelatonin on ovine pars tuberalis membrane homogenates. Structure-activity relationships led to the conclusion that naphthalene is a bioisostere of the indole moiety of melatonin. Moreover it appears that the affinity is strongly affected by the size of the substituent of the nitrogen of the amidic function. Many of these ligands give biphasic dose-response curves which suggests that there may be two melatonin receptor subtypes within the ovine pars tuberalis cells. The replacement of naphthalene by benzofuran or benzothiophene did not strongly alter the affinity for the melatonin receptor. In contrast, the benzimidazole analogue was a poor ligand. Compound 7, the naphthalenic analogue of melatonin, a selective ligand of the melatonin receptor and an agonist derivative, has been selected for clinical development.

Randomised controlled trial comparing hospital at home care with inpatient hospital care. II: cost minimisation analysis

OBJECTIVES

To examine the cost of providing hospital at home in place of some forms of inpatient hospital care.

DESIGN

Cost minimisation study within a randomised controlled trial.

SETTING

District general hospital and catchment area of neighbouring community trust.

SUBJECTS

Patients recovering from hip replacement (n=86), knee replacement (n=86), and hysterectomy (n=238); elderly medical patients (n=96); and patients with chronic obstructive airways disease (n=32).

INTERVENTIONS

Hospital at home or inpatient hospital care.

MAIN OUTCOME MEASURES

Cost of hospital at home scheme to health service, to general practitioners, and to patients and their families compared with hospital care.

RESULTS

No difference was detected in total healthcare costs between hospital at home and hospital care for patients recovering from a hip or knee replacement, or elderly medical patients. Hospital at home significantly increased healthcare costs for patients recovering from a hysterectomy (ratio of geometrical means 1.15, 95% confidence interval 1.04 to 1.29, P=0.009) and for those with chronic obstructive airways disease (Mann-Whitney U test, P=0.01). Hospital at home significantly increased general practitioners' costs for elderly medical patients (Mann-Whitney U test, P<0.01) and for those with chronic obstructive airways disease (P=0.02). Patient and carer expenditure made up a small proportion of total costs.

CONCLUSION

Hospital at home care did not reduce total healthcare costs for the conditions studied in this trial, and costs were significantly increased for patients recovering from a hysterectomy and those with chronic obstructive airways disease. There was some evidence that costs were shifted to primary care for elderly medical patients and those with chronic obstructive airways disease.

Carbamazepine is not a substrate for P-glycoprotein

AIMS

To determine whether the anticonvulsant carbamazepine (CBZ), a known CYP3A4 substrate, is also a substrate for the multidrug efflux transporter P-glycoprotein (Pgp).

METHODS

The role of Pgp in the transport of CBZ was assessed in three systems: (a) in mdr1a/1b(-/-) and wild-type mice after administration of 2 mg kg-1 and 20 mg kg-1, which served as a model for brain penetration; (b) in Caco-2 cells, an in vitro model of the intestinal epithelium that is known to express high Pgp levels; and (c) by flow cytometry in lymphocytes using rhodamine 123, a fluorescent substrate for PgP.

RESULTS

Brain penetration of both doses of CBZ at 1 h and 4 h was comparable in wild-type and mdr1a/1b(-/-) mice. Transport across the Caco-2 cell monolayer was Pgp-independent, and was not affected by the Pgp inhibitor PSC-833. CBZ had no effect on rhodamine 123 efflux from lymphocytes, in contrast to verapamil, which increased fluorescence intensity fivefold.

CONCLUSION

CBZ is not a substrate for Pgp. Its efficacy is unlikely to be affected by Pgp over-expression in the brain. Furthermore, the interaction of CBZ with drugs that modulate both CYP3A4 and Pgp function such as verapamil is probably due to inhibition of CYP3A4 and not Pgp.

Thymic function in young/old chimeras: substantial thymic T cell regenerative capacity despite irreversible age-associated thymic involution

Age-associated thymic involution results in a diminished capacity to regenerate T cell populations, although the magnitude of this effect is unknown. In this report, thymic function was studied in aged vs. young adult mice after lethal irradiation and administration of T cell-depleted bone marrow (BM) from young mice. Abnormalities observed in aged thymi (reduced thymocyte numbers, histologic abnormalities) were not reversed by administration of young BM via bone marrow transplantation (BMT), but aged thymi displayed a normal thymocyte subset distribution and appropriately deleted MIs-reactive T cells after BMT. Aged BMT recipients regenerated significantly reduced numbers of splenic T cells compared to young recipients and showed increased peripheral expansion of thymic emigrants since a higher proportion of BM-derived T cells expressed a memory phenotype in aged vs. young BMT recipients. Because peripheral expansion of thymic emigrants could substantially increase the number of thymic progeny present in the spleen, we sought to measure thymic T cell regenerative capacity after BMT in a setting devoid of peripheral expansion. To do this, TCR-transgenic (Tg+) T cell-depleted BM was administered to aged and young recipients lacking antigen specific for the Tg+ TCR. Aged recipients regenerated approximately 50 % of the TCR Tg+ cells regenerated in young BMT recipients, providing evidence that even very aged thymi retain the capacity to regenerate significant numbers of mature T cell progeny. Therefore, thymic function is reduced with aged but it is not lost, suggesting that therapeutic approaches to enhance thymic function may be successful even in very aged hosts.

GAS-1: a mitochondrial protein controls sensitivity to volatile anesthetics in the nematode Caenorhabditis elegans

BACKGROUND

Mutations in several genes of Caenorhabditis elegans confer altered sensitivities to volatile anesthetics. A mutation in one gene, gas-1(fc21), causes animals to be immobilized at lower concentrations of all volatile anesthetics than in the wild-type, and it does not depend on mutations in other genes to control anesthetic sensitivity. gas-1 confers different sensitivities to stereoisomers of isoflurane, and thus may be a direct target for volatile anesthetics. The authors have cloned and characterized the gas-1 gene and the mutant allele fc21.

METHODS

Genetic techniques for nematodes were as previously described. Polymerase chain reaction, sequencing, and other molecular biology techniques were performed by standard methods. Mutant rescue was done by injecting DNA fragments into the gonad of mutant animals and scoring the offspring for loss of the mutant phenotype.

RESULTS

The gas-1 gene was cloned and identified. The protein GAS-1 is a homologue of the 49-kDa (IP) subunit of the mitochondrial NADH:ubiquinone-oxidoreductase (complex I of the respiratory chain). gas-1(fc21) is a missense mutation replacing a strictly conserved arginine with lysine.

CONCLUSIONS

The function of the 49-kDa (IP) subunit of complex I is unknown. The finding that mutations in complex I increase sensitivity of C elegans to volatile anesthetics may implicate this physiologic process in the determination of anesthetic sensitivity. The hypersensitivity of animals with a mutation in the gas-1 gene may be caused by a direct anesthetic effect on a mitochondrial protein or secondary effects at other sites caused by mitochondrial dysfunction.

Physiology of aliphatic hydrocarbon-degrading microorganisms

This paper reviews aspects of the physiology and biochemistry of the microbial biodegradation of alkanes larger than methane, alkenes and alkynes with particular emphasis upon recent developments. Subject areas discussed include: substrate uptake; metabolic pathways for alkenes and straight and branched-chain alkanes; the genetics and regulation of pathways; co-oxidation of aliphatic hydrocarbons; the potential for anaerobic aliphatic hydrocarbon degradation; the potential deployment of aliphatic hydrocarbon-degrading microorganisms in biotechnology.

Metabolic pathway profiling of mitochondrial respiratory chain mutants in C. elegans

Caenorhabditis elegans affords a model of primary mitochondrial dysfunction that provides insight into cellular adaptations which accompany mutations in nuclear genes that encode mitochondrial proteins. To this end, we characterized genome-wide expression profiles of C. elegans strains with mutations in nuclear-encoded subunits of respiratory chain complexes. Our goal was to detect concordant changes among clusters of genes that comprise defined metabolic pathways. Results indicate that respiratory chain mutants significantly upregulate a variety of basic cellular metabolic pathways involved in carbohydrate, amino acid, and fatty acid metabolism, as well as cellular defense pathways such as the metabolism of P450 and glutathione. To further confirm and extend expression analysis findings, quantitation of whole worm free amino acid levels was performed in C. elegans mitochondrial mutants for subunits of complexes I, II, and III. Significant differences were seen for 13 of 16 amino acid levels in complex I mutants compared with controls, as well as overarching similarities among profiles of complex I, II, and III mutants compared with controls. The specific pattern of amino acid alterations observed provides novel evidence to suggest that an increase in glutamate-linked transamination reactions caused by the failure of NAD(+)-dependent ketoacid oxidation occurs in primary mitochondrial respiratory chain mutants. Recognition of consistent alterations both among patterns of nuclear gene expression for multiple biochemical pathways and in quantitative amino acid profiles in a translational genetic model of mitochondrial dysfunction allows insight into the complex pathogenesis underlying primary mitochondrial disease. Such knowledge may enable the development of a metabolomic profiling diagnostic tool applicable to human mitochondrial disease.

Mucous membrane pemphigoid: a dual circulating antibody response with IgG and IgA signifies a more severe and persistent disease

Mucous membrane pemphigoid (MMP) is an autoimmune blistering disease frequently associated with scarring of involved clinical sites. At present, therapeutic intervention in the form of immunomodulating or immunosuppressive agents is often reserved until the onset of significant inflammation and/or early cicatrization. We have therefore studied the clinical and immunopathological findings in 67 patients with MMP in order to try to establish a reliable prognostic indicator by which patients at high risk may be identified early in the disease. Inclusion criteria were a predominantly mucosal disease and the detection of IgG and/or C3 anti-basement membrane zone (BMZ) immunoreactants using immunofluorescence techniques. Patients were allocated to three disease subgroups on the basis of the modality and duration of therapeutic intervention required to achieve effective control of disease. In addition, at presentation and at each follow-up visit, a clinical score for severity of involved clinical sites was awarded and serum collected for indirect immunofluorescence (IIF). A dual circulating anti-basement membrane zone (anti-BMZ) antibody response with IgG and IgA was significantly associated with a more severe and persistent disease profile (P < 0.001). The odds ratios for requiring systemic therapy were: 11.6 among patients in whom there was a clinical score > or = 5 compared with a score < 5, and 31.3 and 66.9 among patients with IgG alone and both IgG and IgA, respectively, compared with negative IIF. The findings suggest that an assessment based upon a combination of site severity score and the presence of circulating IgG and IgA by IIF using 1 mol/L salt-split human skin substrate may be considered a useful prognostic indicator.