Unique properties of the large antigen of hepatitis delta virus

The large form of the hepatitis delta virus (HDV) protein (L) can be isoprenylated near its C terminus, and this modification is considered essential for particle assembly. Using gel electrophoresis, we separated L into two species of similar mobilities. The slower species could be labeled by the incorporation of [(14)C]mevalonolactone and is interpreted to be isoprenylated L (L(i)). In serum particles, infected liver, transfected cells, and assembled particles, 25 to 85% of L was isoprenylated. Isoprenylation was also demonstrated by (14)C incorporation in vitro with a rabbit reticulocyte coupled transcription-translation system. However, the species obtained migrated even slower than that detected by labeling in vivo. Next, in studies of HDV particle assembly in the presence of the surface proteins of human hepatitis B virus, we observed the following. (i) Relative to L, L(i) was preferentially assembled into virus-like particles. (ii) L(i) could coassemble the unmodified L and the small delta protein, S. (iii) In contrast, a form of L with a deletion in the dimerization domain was both isoprenylated and assembled, but it could not support the coassembly of S. Finally, to test the expectation that the isoprenylation of L would increase its hydrophobicity, we applied a phase separation strategy based on micelle formation with the nonionic detergent Triton X-114. We showed the following. (i) The unique C-terminal 19 amino acids present on L relative to S caused a significant increase in the hydrophobicity. (ii) This increase was independent of isoprenylation. (iii) In contrast, other, artificial modifications at either the N or C terminus of S did not increase the hydrophobicity. (iv) The increased hydrophobicity was not sufficient for particle assembly; nevertheless, we speculate that it might facilitate virion assembly.

We're not in Kansas anymore: a portrait of the new health care consumer. Interview by Shari Mycek

The Baby Boomer generation is a new breed of health care consumer--more educated, more demanding, and more willing to step outside of the traditional medical model. Trustees need to understand the expectations of these consumers so they can make the right decisions about services.

Estimating kinetic parameters from dynamic contrast-enhanced T(1)-weighted MRI of a diffusable tracer: standardized quantities and symbols

We describe a standard set of quantity names and symbols related to the estimation of kinetic parameters from dynamic contrast-enhanced T(1)-weighted magnetic resonance imaging data, using diffusable agents such as gadopentetate dimeglumine (Gd-DTPA). These include a) the volume transfer constant K(trans) (min(-1)); b) the volume of extravascular extracellular space (EES) per unit volume of tissue v(e) (0 < v(e) < 1); and c) the flux rate constant between EES and plasma k(ep) (min(-1)). The rate constant is the ratio of the transfer constant to the EES (k(ep) = K(trans)/v(e)). Under flow-limited conditions K(trans) equals the blood plasma flow per unit volume of tissue; under permeability-limited conditions K(trans) equals the permeability surface area product per unit volume of tissue. We relate these quantities to previously published work from our groups; our future publications will refer to these standardized terms, and we propose that these be adopted as international standards.

Liposomal prostaglandin E1 (TLC C-53) in acute respiratory distress syndrome: a controlled, randomized, double-blind, multicenter clinical trial. TLC C-53 ARDS Study Group

OBJECTIVE

To evaluate the safety and efficacy of an intravenous liposomal dispersion of prostaglandin E1 as TLC C-53 in the treatment of patients with acute respiratory distress syndrome (ARDS).

DESIGN

Randomized, prospective, multicenter, double-blind, placebo-controlled, phase III clinical trial.

SETTING

Forty-seven community and university-affiliated hospitals in the United States.

PATIENTS

A total of 350 patients with ARDS were enrolled in this clinical trial.

INTERVENTION

Patients were prospectively randomized in a 1:1 ratio to receive either liposomal prostaglandin E1 or placebo. The study drug was infused intravenously for 60 mins every 6 hrs for 7 days starting with a dosage of 0.15 microg/kg/hr. The dose was increased every 12 hrs until the maximal dose (3.6 microg/kg/hr) was attained or intolerance to further increases developed. Patients received standard aggressive medical/surgical care during the infusion period.

OUTCOME MEASURES

The primary outcome measure was the time it took to wean the patient from the ventilator. Secondary end points included time to improvement of the PaO2/FIO2 ratio (defined as first PaO2/FIO2 > 300 mm Hg), day 28 mortality, ventilator dependence at day 8, changes in PaO2/FIO2, incidence of and time to development/resolution of organ failure other than ARDS.

RESULTS

A total of 348 patients could be evaluated for efficacy. The distribution of variables at baseline describing gender, lung injury scores, Acute Physiology and Chronic Health Evaluation II scores, PaO2/FIO2, pulmonary compliance, and time from onset of ARDS or from institution of mechanical ventilation to the first dose of study drug was similar among patients in the liposomal prostaglandin E1 (n = 177) and the placebo (n = 171) treatment arms. There was no significant difference in the number of days to the discontinuation of ventilation in the liposomal prostaglandin E1 group compared with the placebo group (median number of days to off mechanical ventilation, 16.9 in patients receiving liposomal prostaglandin E1 and 19.6 in those administered placebo; p = .94). Similarly, mortality at day 28 was not significantly different in the two groups (day 28 mortality, 57 of 176 (32%) in the liposomal prostaglandin E1 group and 50 of 170 (29%) in patients receiving placebo; p = .55). In contrast, treatment with liposomal prostaglandin E1 was associated with a significantly shorter time to reach a PaO2/FIO2 ratio of >300 mm Hg (median number of days to reaching a PaO2/FIO2 ratio >300 mm Hg: 9.8 days in the liposomal prostaglandin E1 group and 13.7 days in patients receiving the placebo; p = .02). Among the subgroups examined, time to off mechanical ventilation was significantly reduced in patients who received at least 85% of a full dose (i.e., > 45.9 microg/kg) of liposomal prostaglandin E1 (median number of days to discontinuation of ventilation, 10.3 in the liposomal prostaglandin E1 group and 16.3 days in patients receiving placebo; p = .05). The overall incidence of serious adverse events was not significantly different in the liposomal prostaglandin E1 (40%) or placebo-treated (37%) groups. Drug-related adverse events of all kinds were reported in 69% of the patients receiving liposomal prostaglandin E1 compared with 33% of the placebo group, with hypotension and hypoxia (occurring in 52% and 24% of the liposomal prostaglandin E1-treated patients, respectively, and 17% and 5% of the placebo-treated patients, respectively) being noted most frequently.

CONCLUSIONS

In the intent-to-treat population of patients with ARDS, treatment with liposomal prostaglandin E1 accelerated improvement in indexes of oxygenation but did not decrease the duration of mechanical ventilation and did not improve day 28 survival.

A study of artefacts in simultaneous PET and MR imaging using a prototype MR compatible PET scanner

We have assessed the possibility of artefacts that can arise in attempting to perform simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) using a small prototype MR compatible PET scanner (McPET). In these experiments, we examine MR images for any major artefacts or loss in image quality due to inhomogeneities in the magnetic field, radiofrequency interference or susceptibility effects caused by operation of the PET system inside the MR scanner. In addition, possible artefacts in the PET images caused by the static and time-varying magnetic fields or radiofrequency interference from the MR system were investigated. Biological tissue and a T2-weighted spin echo sequence were used to examine susceptibility artefacts due to components of the McPET scanner (scintillator, optical fibres) situated in the MR field of view. A range of commonly used MR pulse sequences was studied while acquiring PET data to look for possible artefacts in either the PET or MR images. Other than a small loss in signal-to-noise using gradient echo sequences, there was no significant interaction between the two imaging systems. Simultaneous PET and MR imaging of simple phantoms was also carried out in different MR systems with field strengths ranging from 0.2 to 4.7 T. The results of these studies demonstrate that it is possible to acquire PET and MR images simultaneously, without any significant artefacts or loss in image quality, using our prototype MR compatible PET scanner.

Characterization of the 5' ends for polyadenylated RNAs synthesized during the replication of hepatitis delta virus

The genome of hepatitis delta virus (HDV) is a 1,679-nucleotide (nt) single-stranded circular RNA that is predicted to fold into an unbranched rodlike structure. During replication, two complementary RNAs are also detected: an exact complement, referred to as the antigenome, and an 800-nt polyadenylated RNA that could act as the mRNA for the delta antigen. We used a 5' rapid amplification of cDNA ends procedure, followed by cloning and sequencing, to determine the 5' ends of the polyadenylated RNAs produced during HDV genome replication following initiation under different experimental conditions. The analyzed RNAs were from the liver of an infected woodchuck and from a liver cell line at 6 days after transfection with either an HDV cDNA or ribonucleoprotein (RNP) complexes assembled in vitro with HDV genomic RNA and purified recombinant small delta protein. In all three situations the 5' ends mapped specifically to nt 1630. In relationship to what is called the top end of the unbranched rodlike structure predicted for the genomic RNA template, this site is located 10 nt from the top, and in the middle of a 3-nt external bulge. Following transfection with RNP, such specific 5' ends could be detected as early as 24 h. We next constructed a series of mutants of this predicted bulge region and of an adjacent 6-bp stem and the top 5-nt loop. Some of these mutations decreased the ability of the genome to undergo antigenomic RNA synthesis and accumulation and/or altered the location of the detected 5' ends. The observed end located at nt 1630, and most of the novel 5' ends, were consistent with transcription initiation events that preferentially used a purine. The present studies do not prove that the detected 5' ends correspond to initiation sites and do not establish the hypothesis that there is a promoter element in the vicinity, but they do show that the location of the observed 5' ends could be controlled by nucleotide sequences at and around nt 1630.

Perindopril for elderly people with chronic heart failure: the PEP-CHF study. The PEP investigators

BACKGROUND

The prevalence of chronic heart failure (CHF) rises with increasing age, from < 1% in those below 65 years of age to > 5% in those over 65 years of age and is a major cause of morbidity and mortality in older people. Recent European guidelines point to a major deficiency in our knowledge of how to treat diastolic chronic heart failure, and a lack of information on treatment for heart failure in the elderly in general.

AIMS

The aims of this trial are to assess the potential benefits of the ACE inhibitor perindopril to treat chronic heart failure in elderly people, in the absence of any major left ventricular systolic dysfunction.

SUBJECTS

One thousand people over the age of 70 years will be recruited into this study. Evidence of chronic heart failure will be confirmed by clinical criteria and echocardiography.

METHODS

Once a diagnosis of chronic heart failure has been confirmed, the patient will receive either perindopril or placebo in addition to their usual treatment. Death, and unplanned heart failure related hospitalisations, are the primary outcomes. Quality of life, as measured by the Guyatt questionnaire will be assessed at the beginning of the study and at 1 year. Sub-studies of this trial include a 6-min walking test and more detailed evaluation of ventricular function (as assessed by echocardiography). Both parameters will be measured at 8 weeks and 1 year, and analysed against baseline data. Cognitive function in this group of patients will also be evaluated at baseline and 1 year. This trial is due to report in the year 2001.

Relationship of internalized racism to abdominal obesity and blood pressure in Afro-Caribbean women

Racism is associated with increased psychosocial stress and blood pressure in blacks. However, little is known of the relationship of racism to other features of insulin resistance syndrome. This study examined the relationship of internalized racism to abdominal obesity and elevated blood pressure in a population of black Caribbean women aged 20-55 years. One hundred thirty-three randomly selected women from the island of Barbados comprised the study sample. Data collected included anthropometric and blood pressure measurements, and information about internalized racism, anxiety, and depression. The stress measures including anxiety, depression, and internalized racism were significantly correlated with waist circumference (r = .25, r = .21, and r = .25). After adjusting for age, education, anxiety, and depression, internalized racism remained significantly correlated with waist circumference. The odds ratio associated with development of abdominal obesity among those with high internalized racism (OR = 2.4 [95% CI, 1.1,5.3]) was significant (P < .05) after adjusting for age, education, and body mass index. Blood pressure was not independently related to internalized racism. Studies comparing black-white differences in diseases for which abdominal obesity is a risk factor (eg, diabetes and cardiovascular disease) should take into account the potential role of internalized racism in defining the differences between ethnic groups.

Drink, illicit drugs and unsafe sex in women

AIMS

To establish the extent and nature of linkages between illicit drug and alcohol use and sexual behaviour in women.

PARTICIPANTS AND SETTING

One hundred women attending either a Genitourinary Medicine Clinic or a Family Planning Clinic.

DESIGN

Respondents were interviewed using a semi-structured interview schedule covering the effect of drink/illicit drug use on the incidence of sex, on condom use, and on specific sexual activities, and deliberate use of drink/illicit drugs to affect sex. Interviews focused on the last three new male partners, from the beginning of the sexual relationship through its development. Data analysis was primarily qualitative, quantitative analysis was conducted where appropriate.

RESULTS

There were few cases in which women reported that consumption of drink/illicit drugs caused them to engage in sexual behaviour which they would not have engaged in if they had not had drink/drugs. Associations between drink and illicit drugs and sexual behaviour were, mainly, either because encounters took place in social situations where drugs or drink were being consumed or because the woman used drink or drugs instrumentally to engage in desired behaviours. There was some evidence to suggest that greater use of drugs and alcohol might be part of a wider pattern of social behaviour including more sexual partners.

CONCLUSIONS

The women's self-reported behaviour suggested that illicit drug and alcohol use in itself did not usually result in unsafe or undesired sexual behaviour.

Double gloving and a system for identifying glove perforations in maxillofacial trauma surgery

The treatment of some maxillofacial fractures has an incidence of glove perforation as high as 50%, with over 80% going unnoticed at the time of operation. We investigated double gloving and a glove perforation indication system to ascertain whether the latter offered any additional protection. 1061 gloves used for 113 patients were examined. The outer glove perforation rate was significantly higher than the inner glove (0.48 compared with 0.10, P < 0.0001). There were fewer unnoticed perforations in the glove perforation indication group than the standard surgical glove group (19% compared with 79%, P < 0.0001). The indication system was most effective in wet operating fields. The perforation rate varied with the type of fracture and treatment. Mandibular fractures that were 'hand-held', while bone-plated had a lower mean number of outer glove perforations/operation than fractures treated with temporary intermaxillary fixation (0.43 compared with 4.62, P < 0.0001).

Effects of structure on alpha C-H bond enthalpies of amino acid residues: relevance to H transfers in enzyme mechanisms and in protein oxidation

The bond dissociation enthalpies (BDE) of all of the amino acid residues, modeled by HC(O)NHCH(R)C(O)NH(2) (PH(res)), were determined at the B3LYP/6-31G//B3LYP/6-31G level, coupled with isodesmic reactions. The results for neutral side chains with phi, psi angles approximately 180 degrees, approximately 180 degrees in ascending order, to an expected accuracy of +/-10 kJ mol(-)(1), are Asn 326; cystine 330; Asp 332; Gln 334; Trp 337; Arg 340; Lys 340; Met 343; His 344; Phe 344; Tyr 344; Leu 344; Ala 345; Cys 346; Ser 349; Gly 350; Ile 351; Val 352; Glu 354; Thr 357; Pro-cis 358; Pro-trans 369. BDEs calculated at the ROMP2/6-31G//B3LYP/6-31G level exhibit the same trends but are approximately 7 kJ mol(-)(1) higher. All BDEs are smaller than those of typical secondary or tertiary C-H bonds due to the phenomenon of captodative stabilization. The stabilization is reduced by changes in the phi,psi angles. As a result the BDEs increase by about 10 kJ mol(-)(1) in beta-sheet and 40 kJ mol(-)(1) in alpha-helical environments, respectively. In effect the alpha C-H BDEs can be "tuned" from about 345 to 400 kJ mol(-)(1) by adjusting the local environment. Some very significant effects of this are seen in the current literature on H-transfer processes in enzyme mechanisms and in oxidative damage to proteins. These observations are discussed in terms of the findings of the present study.

Identification of type-specific domains within glycoprotein G of herpes simplex virus type 2 (HSV-2) recognized by the majority of patients infected with HSV-2, but not by those infected with HSV-1

A combination of phage peptide display library mapping and pepscanning, with both murine monoclonal antibodies and a panel of well-characterized human sera, have been used in order to define type-specific epitopes of glycoprotein G of herpes simplex virus type 2 (HSV-2) (gG2). Both techniques revealed an immunodominant region of gG2, centred around amino acids 525-587 of the uncleaved gG2 molecule. A soluble peptide, equivalent to amino acids 551-570, when used as antigen in an ELISA format was recognized by three out of five murine MAbs and by 20/26 (77%) Western blot anti-HSV-2-positive human sera, but by only 1/63 Western blot anti-HSV-2-negative sera (specificity, 98%). The sensitivity of detection of human anti-HSV-2 antibodies was increased to 90% using a peptide derived from this region, presented on a nitrocellulose membrane. This highly antigenic and type-specific domain of gG2 is located at the junction between the 'unique' region of gG2 and its C-terminal end, which has approximately 50% identity with gG1. A second antigenic region of gG2, amino acids 351-427, which lies within the 'unique' part of gG2, was also identified by both techniques employed in this study and is recognized by a proportion of anti-HSV-2-positive sera. These findings demonstrate the feasibility of developing a peptide-based type-specific assay for the detection of anti-HSV-2 antibody in human sera based on type-specific epitopes of gG2 and have implications for the understanding of the three-dimensional topography of gG2.

A comparison of one hundred and fifty consecutive parotidectomies for tumours and inflammatory disease

The demographic profile and complications are compared and contrasted for 150 consecutive parotidectomies. All patients were under the care of one surgeon (JDL) over a twenty-year period (1977-1997). The case records and contemporaneous database were analysed retrospectively. 111 (74%) procedures were performed for tumours and 39 (26%) for inflammatory disease. The incidence of unexpected permanent facial nerve palsy was 1.8% in the tumour group and zero in the inflammatory group. The overall unexpected palsy rate was 1.3%. Transient paralysis was more common in the inflammatory group than the tumour group (61.5% compared with 33.3%, P<0.02) and was more likely to be panfacial (48.7% compared with 17.1%, P<0.0002). The overall incidence of Frey's syndrome was less than 20% and both salivary fistulae and sialocoeles were infrequent.

A minor salivary gland tumour presenting with dysphagia

A case is reviewed of a giant benign myoepithelioma of the soft palate presenting in an elderly female patient. Due to the large size of the lesion and its mass effect the patient developed dysphagia with subsequent significant weight loss. The clinico-pathological features of this rare tumour are described and the literature reviewed.

Nursing implications of a vancomycin resistant enterococcus outbreak in a renal unit

Vancomycin Resistant Enterococcus is a difficult organism to treat and is becoming more prevalent world-wide. When it was identified in a busy renal unit, radical and expensive measures were taken to try and control the outbreak. Although these had costs to both patients and staff, the organism was eradicated from the unit.

ABC medium, a new chromogenic agar for selective isolation of Salmonella spp

We describe a new chromogenic agar medium, ABC medium (alphabeta-chromogenic medium), which includes two substrates, 3, 4-cyclohexenoesculetin-beta-D-galactoside and 5-bromo-4-chloro-3-indolyl-alpha-D-galactopyranoside, to facilitate the selective isolation of Salmonella spp. This medium exploits the fact that Salmonella spp. may be distinguished from other members of the family Enterobacteriaceae by the presence of alpha-galactosidase activity in the absence of beta-galactosidase activity. A total of 1, 022 strains of Salmonella spp. and 300 other gram-negative strains were inoculated onto this medium. Of these, 1,019 (99.7%) strains of Salmonella spp. produced a characteristic green colony, whereas only 1 strain (0.33%) of non-Salmonella produced a green colony. A total of 283 stool samples were cultured onto desoxycholate citrate (DC) agar and ABC medium by direct inoculation and after selective enrichment in selenite broth. Overall, the sensitivity and specificity were superior for ABC medium (100 and 90.5%, respectively) than for DC agar (88 and 26.9%, respectively). We conclude that ABC medium offers a high degree of specificity for the detection of Salmonella spp. in stool samples.

Individual differences in electrodermal responsivity to predictable aversive stimuli and substance dependence

To determine if the inability to take advantage of the predictability of an aversive stimulus to diminish its psychological impact reflects a deficit in inhibitory control related to the development of substance dependence, we recorded skin conductance responses (SCRs), heart rate (HR), and anticipatory electrodermal nonspecific fluctuations (NSFs) from 175 16-18-year-old boys when a white noise blast was either unpredictable or temporally predictable. Compared with boys who had moderately reduced or augmented SCRs to predictable blasts (moderate and poor modulators, respectively), boys whose SCRs were greatly reduced (good modulators) had fewer symptoms of alcohol and nicotine dependence and more anticipatory NSFs. HR appeared to index an active coping response for good and moderate modulators. The autonomic response pattern evident for good modulators may index an inhibitory control mechanism protecting them from developing substance dependence.

Episodic retrieval activates the precuneus irrespective of the imagery content of word pair associates. A PET study

The aim of this study was to evaluate further the role of the precuneus in episodic memory retrieval. The specific hypothesis addressed was that the precuneus is involved in episodic memory retrieval irrespective of the imagery content. Two groups of six right-handed normal male volunteers took part in the study. Each subject underwent six [15O]butanol-PET scans. In each of the six trials, the memory task began with the injection of a bolus of 1500 MBq of [15O]butanol. For Group 1, 12 word pair associates were presented visually, for Group 2 auditorily. The subjects of each group had to learn and retrieve two sets of 12 word pairs each. One set consisted of highly imaginable words and another one of abstract words. Words of both sets were not related semantically, representing 'hard' associations. The presentations of nonsense words served as reference conditions. We demonstrate that the precuneus shows consistent activation during episodic memory retrieval. Precuneus activation occurred in visual and auditory presentation modalities and for both highly imaginable and abstract words. The present study therefore provides further evidence that the precuneus has a specific function in episodic memory retrieval as a multimodal association area.

Mucosal vaccination with recombinant poxvirus vaccines protects ferrets against symptomatic CDV infection

Canine distemper virus (CDV) infection of ferrets causes a disease characterized by fever, erythema, conjunctivitis and leukocytopenia, similar clinically to measles except for the fatal neurologic sequelae of CDV. We vaccinated juvenile ferrets twice at 4-week intervals by the intranasal or intraduodenal route with attenuated vaccinia (NYVAC) or canarypox virus (ALVAC) constructs containing the CDV hemagglutinin and fusion genes. Controls were vaccinated with the same vectors expressing rabies glycoprotein. Animals were challenged intranasally 4 weeks after the second vaccination with virulent CDV. Body weights, white blood cell (WBC) counts and temperatures were monitored and ferrets were observed daily for clinical signs of infection. WBCs were assayed for the presence of viral RNA by RT-PCR. Intranasally vaccinated animals survived challenge with no virologic or clinical evidence of infection. Vaccination by the intraduodenal route did not provide complete protection. All control animals developed typical distemper. Ferrets can be effectively protected against distemper by mucosal vaccination with poxvirus vaccines.

Expression, purification and crystallization of a BH domain from the GTPase regulatory protein associated with focal adhesion kinase

Signaling by small GTPases is down-regulated by GTPase activating proteins (GAPs) which enhance the rate of GTP hydrolysis. The activity of GAPs specific for Rho GTPases resides in the BH domain, many homologues of which are found in any mammalian genome. One of them was identified in the GTPase regulator associated with focal-adhesion kinase (GRAF). It shares approximately 20% sequence identity with p50RhoGAP. This GAP activates RhoA and Cdc42Hs, but not Rac. In order to dissect the molecular basis of this specificity, a 231-residue-long fragment corresponding to the BH domain of GRAF has been expressed, purified and crystallized. Trigonal crystals, of space group P3(1)21 or P3(2)21, with unit-cell dimensions a = b = 63.5, c = 90.38 A were grown from solutions of PEG 6000. Data to 2.15 A were collected from a flash-frozen sample on an R-AXIS IV imaging-plate detector mounted on a rotating anode X-ray generator.

Reduced cytosolic acidification during exercise suggests defective glycolytic activity in skeletal muscle of patients with Becker muscular dystrophy. An in vivo 31P magnetic resonance spectroscopy study

Becker muscular dystrophy is an X-linked disorder due to mutations in the dystrophin gene, resulting in reduced size and/or content of dystrophin. The functional role of this subsarcolemma protein and the biochemical mechanisms leading to muscle necrosis in Becker muscular dystrophy are still unknown. In particular, the role of a bioenergetic deficit is still controversial. In this study, we used 31p magnetic resonance spectroscopy (31p-MRS) to investigate skeletal muscle mitochondrial and glycolytic ATP production in vivo in 14 Becker muscular dystrophy patients. Skeletal muscle glycogenolytic ATP production, measured during the first minute of exercise, was similar in patients and controls. On the other hand, during later phases of exercise, skeletal muscle in Becker muscular dystrophy patients was less acidic than in controls, the cytosolic pH at the end of exercise being significantly higher in Becker muscular dystrophy patients. The rate of proton efflux from muscle fibres of Becker muscular dystrophy patients was similar to that of controls, pointing to a deficit in glycolytic lactate production as a cause of higher end-exercise cytosolic pH in patients. The maximum rate of mitochondrial ATP production was similar in muscle of Becker muscular dystrophy patients and controls. The results of this in vivo 31P-MRS study are consistent with reduced glucose availability in dystrophin-deficient muscles.