Markovian models of low and high activity levels of cardiac ryanodine receptors

The modal gating behavior of single sheep cardiac sarcoplasmic reticulum (SR) Ca2+-release/ryanodine receptor (RyR) channels was assessed. We find that the gating of RyR channels spontaneously shifts between high (H) and low (L) levels of activity and inactive periods where no channel openings are detected (I). Moreover, we find that there is evidence for multiple gating modes within H activity, which we term H1 and H2 mode. Our results demonstrate that the underlying mechanisms regulating gating are similar in native and purified channels. Dwell-time distributions of L activity were best fitted by three open and five closed significant exponential components whereas dwell-time distributions of H1 activity were best fitted by two to three open and four closed significant exponential components. Increases in cytosolic [Ca2+] cause an increase in open probability (Po) within L activity and an increase in the probability of occurrence of H activity. Open lifetime distributions within L activity were Ca2+ independent whereas open lifetime distributions within H activity were Ca2+ dependent. This study is the first attempt to estimate RyR single-channel kinetic parameters from sequences of idealized dwell-times and to develop kinetic models of RyR gating using the criterion of maximum likelihood. We propose distinct kinetic schemes for L, H1, and H2 activity that describe the major features of sheep cardiac RyR channel gating at these levels of activity.

The fungus Pestalotiopsis guepini as a model for biotransformation of ciprofloxacin and norfloxacin

The metabolism of the fluoroquinolone drugs ciprofloxacin and norfloxacin by Pestalotiopsis guepini strain P-8 was investigated. Cultures were grown at 28 degrees C in sucrose/peptone broth for 18 days after dosing with ciprofloxacin (300 microM) or norfloxacin (313 microM). Four major metabolites were produced from each drug; and these were purified by high-performance liquid chromatography and identified by mass spectrometry and proton nuclear magnetic resonance spectroscopy. Ciprofloxacin metabolites included N-acetylciprofloxacin (52.0%), desethylene-N-acetylciprofloxacin (9.2%), N-formylciprofloxacin (4.2%), and 7-amino-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (2.3%). Norfloxacin metabolites included N-acetylnorfloxacin (55.4%), desethylene-N-acetylnorfloxacin (8.8%), N-formylnorfloxacin (3.6%), and 7-amino-1-ethyl-6-fluoro4-oxo-1,4-dihydroquinoline-3-carboxylic acid (2.1%). N-Formylciprofloxacin and the four transformation products from norfloxacin are all known to be mammalian metabolites.

Identification of differentially expressed genes in hepatocellular carcinoma and metastatic liver tumors by oligonucleotide expression profiling

BACKGROUND

The characterization of differentially expressed genes between cancerous and normal tissues is an important step in the understanding of tumorigenesis. Global gene expression profiling with microarrays has now offered a powerful tool to measure the changes of thousands of genes in any carcinoma tissues in an effort to identify these key disease-related genes. To compare the gene expression of a primary liver carcinoma, metastatic carcinoma to the liver, and normal liver, the authors analyzed tissue from six primary hepatocellular carcinomas (HCCs), five colorectal adenocarcinoma metastases to the liver, and eight normal livers.

METHODS

Samples were processed from total RNA to fragmented cRNA and hybridized onto Affymetrix GeneChip(R) expression arrays. Analyses were performed to determine the consensus pattern of gene expression for primary liver carcinoma, metastatic liver carcinoma, and normal liver tissue and their changes in expression level.

RESULTS

In hepatocellular carcinoma, 842 genes were overexpressed, and 393 genes were underexpressed in comparison with genes of normal liver tissue. Of note, 7 of the 20 most increased identified known genes previously have been associated with liver carcinoma or other types of cancers. The 13 additional identified genes until now have not previously shown strong association with cancers. Furthermore, the authors identified 42 genes and 24 expressed sequence tags that are expressed at a significant level in both HCC and metastastic tumors, presenting a list of marker genes indicative of cancerous liver tissue.

CONCLUSIONS

In this study, genes that can be involved in the production of and maintenance of hepatic carcinomas were identified. These data offer new insight into genes that are potentially important in the pathogenesis of liver carcinoma, as well as additional targets for new strategies for cancer therapy and treatment.

An expert system for automated structure elucidation utilizing 1H-1H, 13C-1H and 15N-1H 2D NMR correlations

A software program for the automated structure elucidation of complex organic molecules using an expert system and utilizing 2D homo- and heteronuclear correlation 1H, 13C and 15N NMR spectroscopy is described. The methodology is illustrated on the basis of the automated structure determination of strychnine and some other examples.

The high prevalence of autoantibodies to tissue transglutaminase in first-degree relatives of patients with type 1 diabetes is not associated with islet autoimmunity

OBJECTIVE

To determine the extent of celiac autoimmunity in type 1 diabetic patients and the overlap between islet and celiac autoimmunity in their nondiabetic relatives.

RESEARCH DESIGN AND METHODS

IgA antibodies to tissue transglutaminase were determined in serum taken from 433 type 1 diabetic patients and 1,442 nondiabetic first-degree relatives. Samples with transglutaminase antibodies above the 97.5th percentile of 347 schoolchildren were also assayed for IgA anti-endomysial antibodies (EMAs). Markers of islet autoimmunity (islet cell antibodies and autoantibodies to insulin, glutamate decarboxylase. and protein tyrosine phosphatase IA-2) had previously been measured in all relatives.

RESULTS

In the absence of known celiac disease, the prevalence of transglutaminase antibody levels above the 97.5th percentile of the schoolchildren was 13.4% in diabetic patients and 7.0% in nondiabetic relatives. ENMAs were found in addition to transglutaminase antibodies in 2.6% of probands and in 1.9% of first-degree relatives, but none of the schoolchildren. Transglutaminase antibodies were found to persist in 10 of 30 patients and in 30 of 59 relatives with follow-up samples taken at least 2 years after the initial sample. Of 186 nondiabetic relatives with islet autoantibodies, only 10 also had transglutaminase antibodies.

CONCLUSIONS

We found a high prevalence of celiac autoimmunity in patients and first-degree relatives of children with type 1 diabetes, but we found limited overlap between islet and celiac autoimmunity in nondiabetic relatives. The high prevalence of celiac autoimmunity may be explained by shared genetic susceptibility and identifies a population within which screening for the disease may be justified.

Metabolism of the veterinary fluoroquinolone sarafloxacin by the fungus Mucor ramannianus

To investigate the microbial biotransformation of veterinary fluoroquinolones, Mucor ramannianus was grown in sucrose/peptone broth with sarafloxacin for 18 days. Cultures were extracted with ethyl acetate and extracts were analyzed by liquid chromatography. The two metabolites (26% and 15% of the A280, respectively) were identified by mass and 1H nuclear magnetic resonance spectra as N-acetylsarafloxacin and desethylene-N-acetylsarafloxacin. The biological formation of desethylene-N-acetylsarafloxacin has not been previously observed.

Determination of absorbed dose calibration factors for therapy level electron beam ionization chambers

Over several years the National Physical Laboratory (NPL) has been developing an absorbed dose calibration service for electron beam radiotherapy. To test this service, a number of trial calibrations of therapy level electron beam ionization chambers have been carried out during the last 3 years. These trials involved 17 UK radiotherapy centres supplying a total of 46 chambers of the NACP, Markus, Roos and Farmer types. Calibration factors were derived from the primary standard calorimeter at seven energies in the range 4 to 19 MeV with an estimated uncertainty of +/-1.5% at the 95% confidence level. Investigations were also carried out into chamber perturbation, polarity effects, ion recombination and repeatability of the calibration process. The instruments were returned to the radiotherapy centres for measurements to be carried out comparing the NPL direct calibration with the 1996 IPEMB air kerma based Code of Practice. It was found that, in general, all chambers of a particular type showed the same energy response. However, it was found that polarity and recombination corrections were quite variable for Markus chambers-differences in the polarity correction of up to 1% were seen. Perturbation corrections were obtained and were found to agree well with the standard data used in the IPEMB Code. The results of the comparison between the NPL calibration and IPEMB Code show agreement between the two methods at the +/-1% level for the NACP and Farmer chambers, but there is a significant difference for the Markus chambers of around 2%. This difference between chamber types is most likely to be due to the design of the Markus chamber.

Pneumocystis carinii pneumonia and cytomegalovirus infection in children with vertically acquired HIV infection

OBJECTIVES

The outcome of Pneumocystis carinii pneumonia (PCP) in HIV-infected infants is poor, and the role of cytomegalovirus (CMV) co-infection in the course and outcome of PCP is unclear. This study describes the prevalence, clinical characteristics, management and changes in survival over time of vertically HIV-infected infants developing PCP and/or CMV infection.

METHODS

Data on children with HIV, born in the UK and Ireland and reported to the National Study of HIV in Pregnancy and Childhood, with PCP and/or CMV were combined with clinical information collected from reporting paediatricians.

RESULTS

By April 1998, 340 vertically HIV-infected children had been reported, of whom 93 had PCP and/or CMV, as their first AIDS indicator disease; 85 (91%) were infants. Among infants with PCP, 79% were born to mothers not diagnosed as HIV infected, and there was an independent and statistically significant association with breast-feeding, being black African, and developing CMV disease. Median survival after PCP and/or CMV was significantly better in those born between 1993 and 1998 compared with those born before 1993 (P = 0.009), and worse than after other AIDS diagnoses (P = 0.01). Infants with dual infection were more likely to be ventilated (P = 0.003) and receive corticosteroids (P = 0.002) than those with PCP alone.

CONCLUSION

Although survival from PCP and CMV has improved over time, these remain serious and potentially fatal infections among infants in whom maternal HIV status is not recognized in pregnancy. Breast-feeding increases the risk of combined PCP and CMV infection, which is associated with severe disease.

Light at the end of the Ca(2+)-release channel tunnel: structures and mechanisms involved in ion translocation in ryanodine receptor channels

RyR and InsP3R are Ca(2+)-release channels. When induced to open by the appropriate stimulus, these channels allow Ca2+ to leave intracellular storage organelles at an astonishing rate. Investigations of the ion-handling properties of isolated RyR channels have demonstrated that, at least in comparison to voltage-gated channels of surface membranes, these channels display limited powers of discrimination between physiologically relevant cations and this relative lack of selectivity is likely to contribute to the ability of Ca(2+)-release channels to maintain high rates of cation translocation without compromising function. A range of ion-handling properties in RyR are consistent with the proposal that this channel functions as a single-ion channel and theoretical considerations indicate that the high rates of ion translocation monitored for RyR would require the pore of such a structure to be short and possess a large capture radius. Measurements of the dimensions of regions of RyR involved in ion conduction and discrimination indicate that this is likely to be the case. In each monomer of RyR/InsP3R, residues making up the last two trans-membrane spanning domains and a luminal loop linking these two helices contribute to the formation of the channel pore. The luminal loops of both RyR and InsP3R contain amino acid sequences similar to those known to form the selectivity filter of K+ channels. In addition the luminal loops of both Ca(2+)-release channels contain sequences that are likely to form helices that may be analogous to the pore helix visualised in KcsA. The correlation in structural elements of the luminal loops of RyR/InsP3R and KcsA has prompted us to speculate on the tertiary arrangement for this region of the Ca(2+)-release channels using the established structure of KcsA as a framework.

Right ventricular hypertrophy secondary to pulmonary hypertension is linked to rat chromosome 17: evaluation of cardiac ryanodine Ryr2 receptor as a candidate

BACKGROUND

Fischer 344 (F344) rats are relatively resistant to hypoxia-induced right ventricular (RV) hypertrophy compared with the Wistar-Kyoto (WKY) strain. These 2 strains were used to examine the genetic basis for the differential response.

METHODS AND RESULTS

Male F(2) offspring from an F344xWKY intercross were exposed to hypoxia (10% O(2)) for 3 weeks, and pulmonary artery pressure and cardiac chamber weights were measured. Genomic DNA was screened by use of polymorphic microsatellite markers across the whole genome (excluding the sex chromosomes). A quantitative trait locus (QTL) for RV weight was identified on rat chromosome 17 (lod score 6.5) that accounted for 22% of the total variance of RV weight in the F(2) population and was independent of pulmonary artery pressure. The peak was centered over marker D17Rat41, close to Chrm3, with a 1-lod support interval of 5 cM. Comparison of homologous regions in mice and humans suggested that Ryr2, the cardiac isoform of the ryanodine receptor, colocalizes with our QTL. A panel of somatic cell hybrids and fluorescence in situ hybridization mapped Ryr2 close to the gene Chrm3 within our QTL. [(3)H]Ryanodine binding to cardiac membranes from the parental strains showed a 21% reduction in B(max) in the WKY compared with the F344 strain, with no difference in K:(d).

CONCLUSIONS

These data provide the first demonstration of a QTL linked to the RV response to hypoxia-induced pulmonary hypertension. The Ryr2 receptor gene lies within this QTL and merits further investigation as a candidate for this differential RV response.

Characterization of the ryanodine receptor-Ca2+ release channel from the thoracic tissues of the lepidopteran insect Heliothis virescens

The existence of invertebrate forms of the RyR has recently been confirmed (Takeshima et al., 1994, Puente et al., 2000). However, information on the functional properties of this insect RyR is still limited. We report the functional characterization of a RyR from the thoracic muscle of H. virescens (Scott-Ward et al., 1997). A simple purification protocol produced membranes from homogenized prefrozen H. virescens thoracic muscle with a [3H]-ryanodine binding activity of 1.19 +/- 0.21 pmol/mg protein (mean +/- SE; n = 4). [3H]-Ryanodine binding to the H. virescens receptor was dependent on the ryanodine concentration in a hyperbolic fashion with a KD of 3.82 nM (n = 4). [3H]-ryanodine binding was dependent on [Ca2+] in a biphasic manner and was stimulated by 1 mM ATP. Millimolar caffeine did not stimulate [3H]-ryanodine binding to H. virescens membranes in the presence of either nanomolar or micromolar Ca2+. A protein of at least 400 KDa was recognized in H. virescens membrane proteins by a specific anti-H. virescens RyR antibody. Discontinuous density sucrose gradient fractionation of microsomal membranes produced vesicles suitable for single-channel studies. Ca2+-sensitive, Ca2+-permeable channels were successfully inserted into artificial lipid bilayers from H. virescens membrane vesicles. The H. virescens RyR-channel displayed a Ca2+ conductance of approximately 110 pS and underwent a persistent and characteristic modification of ion handling and gating following addition of 100 nM ryanodine. The gating of H. virescens channels was sensitive to ATP and ruthenium red in a manner similar to mammalian RyR. This is the first report to describe the single channel and [3H]-ryanodine binding properties of a native insect RyR.

A comparison of the prevalence of islet autoantibodies in children from two countries with differing incidence of diabetes

AIMS/HYPOTHESIS

To examine the prevalence of sub-: clinical islet autoimmunity in children from two countries with a twofold to threefold difference in incidence of childhood Type I (insulin-dependent) diabetes mellitus.

METHODS

Sera were collected from 2,860 English and 3,053 Lithuanian non-diabetic schoolchildren according to the same protocol. Occult diabetes was excluded by blood glucose measurement. Antibodies to GAD and the protein tyrosine phosphatase IA-2 were measured with standardised radiobinding assays in a single laboratory. Islet cell antibodies and insulin autoantibodies were additionally measured in all samples with GAD and/or IA-2 antibody levels above the 97.5th centile of the English schoolchildren.

RESULTS

Of Lithuanian schoolchildren 2.7 % had GAD antibodies above the 97.5th centile of the English schoolchildren but only 0.2 % had antibodies to IA-2 above this threshold (p < 0.001). Islet cell and/ or insulin autoantibodies above the 97.5th centile were found in 22 Lithuanian and 16 English schoolchildren and the overall prevalence of two or more antibodies on or above the 97.5th centile was similar [0.7 % (0.5-1.1) vs 0.6 % (0.4-1.0)] in the two cohorts.

CONCLUSION/INTERPRETATION

The prevalence of multiple antibody markers was similar in the cohorts from the two populations, despite the two to three-fold difference in incidence of diabetes. The unexpectedly high prevalence of subclinical islet autoimmunity suggests that the incidence of diabetes in Lithuania is likely to increase in the near future.

Gram-negative bacteria induce proinflammatory cytokine production by monocytes in the absence of lipopolysaccharide (LPS)

Tumour necrosis factor-alpha (TNF-alpha), IL-1alpha and IL-6 production by human monocytes in response to a clinical strain of the Gram-negative encapsulated bacteria Neisseria meningitidis and an isogenic lpxA- strain deficient in LPS was investigated. Wild-type N. meningitidis at concentrations between 105 and 108 organisms/ml and purified LPS induced proinflammatory cytokine production. High levels of these cytokines were also produced in response to the lpxA- strain at 107 and 108 organisms/ml. The specific LPS antagonist bactericidal/permeability-increasing protein (rBPI21) inhibited cytokine production induced by LPS and wild-type bacteria at 105 organisms/ml but not at higher concentrations, and not by LPS-deficient bacteria at any concentration. These data show that proinflammatory cytokine production by monocytes in response to N. meningitidis does not require the presence of LPS. Therapeutic strategies designed to block LPS alone may not therefore be sufficient for interrupting the inflammatory response in severe meningococcal disease.

Extensive enteric leiomyolysis due to cytomegalovirus enterocolitis in vertically acquired human immunodeficiency virus infection in infants

We report two infants with the acquired immunodeficiency syndrome (AIDS) and rectal bleeding due to cytomegalovirus (CMV) ileitis and colitis with minimal focal mucosal ulceration but with extensive leiomyolysis of the muscularis propria. Immunostaining and in situ hybridization for CMV showed numerous viral inclusions in the myocytes of the muscularis propria and vascular endothelium/smooth muscle with only occasional inclusions present in the muscularis mucosae. Colectomy was curative in one patient; in the other the bowel was only examined at postmortem.

DNA adduct formation by Fusarium culture extracts: lack of role of fusarin C

Fusarium fungi have been shown to infect corn and other crops worldwide, and have a significant impact on human health through loss of crops or contamination of food with mycotoxins. Isolates of Fusarium fungi from an area of South Africa with high incidence of esophageal cancer have been shown to induce esophageal and liver cancer in rats. Several isolates of Fusarium fungi were grown on corn to determine if genotoxic products were produced. We report the incubation of methanol extracts of Fusarium verticillioides cultures with DNA in the presence of rat liver fractions (S9) resulted in the formation of a unique DNA adduct that was detected by (32)P-postlabeling. Fusarin C was purified from cultures of Fusarium verticillioides RRC 415, and was not responsible for the formation of the DNA adduct. Treatment of the methanolic extracts with ultraviolet B radiation reduced the fusarin C content in the extract; however, this had no effect on the formation of the DNA adduct following incubation of the extract with DNA and S9. The unique DNA adduct was formed following the incubation of several Fusarium verticillioides isolates from the US and South Africa, while extracts of cultures of Fusarium graminearium and Fusarium sacchari isolates formed very little of the DNA adduct when incubated with DNA and S9. These data suggest that neither fusarin C nor any of its metabolites are responsible for formation of the DNA adduct, and that an unidentified compound is present in F. verticillioides cultures that forms a DNA adduct, and may be important in the etiology of human esophageal cancer.

Evidence for Ca(2+) activation and inactivation sites on the luminal side of the cardiac ryanodine receptor complex

We have used tryptic digestion to determine whether Ca(2+) can regulate cardiac ryanodine receptor (RyR) channel gating from within the lumen of the sarcoplasmic reticulum (SR) or whether Ca(2+) must first flow through the channel and act via cytosolically located binding sites. Cardiac RyRs were incorporated into bilayers, and trypsin was applied to the luminal side of the bilayer. We found that before exposure to luminal trypsin, the open probability of RyR was increased by raising the luminal [Ca(2+)] from 10 micromol/L to 1 mmol/L, whereas after luminal trypsin exposure, increasing the luminal [Ca(2+)] reduced the open probability. The modification in the response of RyRs to luminal Ca(2+) was not observed with heat-inactivated trypsin, indicating that digestion of luminal sites on the RyR channel complex was responsible. Our results provide strong evidence for the presence of luminally located Ca(2+) activation and inhibition sites and indicate that trypsin digestion leads to selective damage to luminal Ca(2+) activation sites without affecting luminal Ca(2+) inactivation sites. We suggest that changes in luminal [Ca(2+)] will be able to regulate RyR channel gating from within the SR lumen, therefore providing a second Ca(2+)-regulatory effect on RyR channel gating in addition to that of cytosolic Ca(2+). This luminal Ca(2+)-regulatory mechanism is likely to be an important contributing factor in the potentiation of SR Ca(2+) release that is observed in cardiac cells in response to increases in intra-SR [Ca(2+)].

Proteasome inhibitor PS519 reduces infarction and attenuates leukocyte infiltration in a rat model of focal cerebral ischemia

BACKGROUND AND PURPOSE

Reperfusion brain injury after cerebral ischemia is associated with a developing inflammatory response at the site of infarction. Proteasome inhibitors block nuclear factor-kappaB activation and provide anti-inflammatory effects in several animal models of peripheral inflammation. We tested the novel proteasome inhibitor PS519 in a rat model of transient focal ischemia to establish its pharmacodynamics as a neuroprotection treatment and related effects on leukocyte infiltration.

METHODS

Rats were subjected to 2 hours of focal cerebral ischemia by means of the filament method of middle cerebral artery occlusion (MCAo). After either 22 or 70 hours of reperfusion, infarct size was measured and neurological function, electroencephalographic (EEG) activity, and/or neutrophil and macrophage infiltration was quantified. PS519 was administered in a single intravenous bolus at 2 hours after MCAo. In addition, the therapeutic window for PS519 was estimated by delaying treatment for 4 or 6 hours after MCAo.

RESULTS

Dose-response analysis of infarct volume at 24 hours revealed that PS519 neuroprotection approached 60%, and clinical evaluations showed significant improvements in neurological function and EEG activity. Neutrophil infiltration at 24 hours was also significantly decreased in cortical and striatal infarcted tissue of PS519-treated rats. Delaying the PS519 treatment up to 4 hours continued to result in significant neuroprotection. In the 72-hour injury model, infarction was reduced 40% by PS519, and significant improvements in neurological function and EEG recovery were again measured. Considerable reductions in both neutrophil and macrophage infiltration were evident.

CONCLUSIONS

PS519 mitigates infarction and improves neurological recovery in brain-injured rats, an effect in part caused by a reduction in the leukocyte inflammatory response.

Neuroprotective efficacy and therapeutic window of the high-affinity N-methyl-D-aspartate antagonist conantokin-G: in vitro (primary cerebellar neurons) and in vivo (rat model of transient focal brain ischemia) studies

Conantokin-G (Con-G), a 17-amino-acid peptide derived from marine snails and a potent N-methyl-D-aspartate (NMDA) antagonist, was evaluated for its neuroprotective properties in vitro and in vivo. In primary cerebellar neurons, Con-G was shown to decrease excitotoxic calcium responses to NMDA and to exhibit differential neuroprotection potencies against hypoxia/hypoglycemia-, NMDA-, glutamate-, or veratridine-induced injury. Using the intraluminal filament method of middle cerebral artery occlusion as an in vivo rat model of transient focal brain ischemia, the neuroprotective dose-response effect of Con-G administration beginning 30 min postocclusion was evaluated after 2 h of ischemia and 22 h of reperfusion. In the core region of injury, an 89% reduction in brain infarction was measured with significant neurological and electroencephalographic recovery at the maximal dose tested (2 nmol), although mild sedation was noted. Lower doses of Con-G (0.001-0.5 nmol) were significantly neuroprotective without causing sedation. Postinjury time course experiments demonstrated a therapeutic window out to at least 4 to 8 h from the start of the injury, providing a 47% reduction in core injury. The neuroprotective effect of Con-G (0. 5 nmol) was also evaluated after 72 h of injury, where a 54% reduction in core brain infarction was measured. Critically, in both recovery models (i.e., 24 and 72 h), the reduction in brain infarction was associated with significant improvements in neurological and electroencephalographic recovery. These data provide evidence for the potent and highly efficacious effect of Con-G as a neuroprotective agent, with an excellent therapeutic window for the potential intervention against ischemic/excitotoxic brain injury.

Microbiological transformation of enrofloxacin by the fungus Mucor ramannianus

Enrofloxacin metabolism by Mucor ramannianus was investigated as a model for the biotransformation of veterinary fluoroquinolones. Cultures grown in sucrose-peptone broth were dosed with enrofloxacin. After 21 days, 22% of the enrofloxacin remained. Three metabolites were identified: enrofloxacin N-oxide (62% of the total absorbance), N-acetylciprofloxacin (8.0%), and desethylene-enrofloxacin (3.5%).

Rapid eye movement sleep behaviour disorder, depression and cognitive impairment. Case study

BACKGROUND

Rapid eye movement (REM) sleep behaviour disorder is a relatively new diagnostic category. It has never before been associated with a treatable depressive condition.

AIMS

To report on a 74-year-old man with a history of depression and REM sleep behaviour disorder, associated with mild cognitive impairment.

METHOD

Assessment using brain CT, MRI, PET, electroencephalography, neuropsychological testing and nocturnal polysomnography.

RESULTS

Depression was treated with sertraline. Sleep laboratory studies supported a diagnosis of REM sleep behaviour disorder, which was treated with clonazepam. Sleep apnoea, revealed later, was treated with nasal continuous positive airways pressure. Brain MRI showed mild atrophy, but neuropsychological testing indicated no progressive cognitive deterioration.

CONCLUSIONS

This case draws attention to REM sleep behaviour disorder and its potential interaction with depression and cognitive impairment, producing symptoms which can be mistaken for early dementia. The diagnosis of REM sleep behaviour disorder is easily missed, and it requires careful history-taking and sleep investigation in all suspected sufferers. Associated neurological, sleep and psychiatric conditions (including depression and cognitive impairment) may confound the diagnosis.

The snuffbox arteriovenous fistula for vascular access

OBJECTIVES

to determine the applicability, patency rates and factors influencing patency of snuffbox arteriovenous fistulae for haemodialysis access.

DESIGN

retrospective non-randomised study.

MATERIALS AND METHODS

patency was determined by reference to an ongoing database and dialysis records of 645 vascular access procedures between 1985 and 1997, including 210 snuffbox fistulae in 201 patients.

RESULTS

snuffbox fistulae comprised 189/376 (50%) primary procedures. Records of 208 snuffbox fistulae were available for patency analysis by the life-table method. Twenty-two (11%) thrombosed within 24 hours of operation. After six weeks 80% were used for dialysis. Cumulative patency was 65% at 1 year and 45% at 5 years. After thrombosis of snuffbox fistulae, ipsilateral wrist fistulae could be constructed in 45%. Fistula patency was significantly better in men than women (p<0.001) and for left- than right-sided fistulae (p<0.001). Diabetes, age >70 years, and the prior commencement of haemodialysis did not significantly affect fistula survival.

CONCLUSIONS

the snuffbox AV fistula gives a long segment of arterialised vein for needling and preserves proximal vessels. It is feasible in 50% of patients requiring primary access and has good long-term patency, especially in men. A more proximal fistula may be preferable in women with smaller vessels.