Clinical progression of mitochondrial myopathy is associated with the random accumulation of cytochrome c oxidase negative skeletal muscle fibres.

We studied the accumulation of cytochrome c oxidase (COX)-negative skeletal muscle fibres in six patients with a myopathy due to a mitochondrial DNA (mtDNA) defect. Each patient was biopsied on two or more occasions over a period of 3-15 years. Progressive proximal weakness was associated with an increase in the proportion of COX-negative fibres.

Sugars regulate cold-induced gene expression and freezing-tolerance in barley cell cultures.

The hypothesis that the extracellular concentration of sugars helps regulate the acclimation of plant cells to cold was tested in this work. Suspension cultures were used to control the concentration of sugars in the medium supplied to barley cell cultures (Hordeum vulgare L. cv.

The alpha-glucuronidase, GlcA67A, of Cellvibrio japonicus utilizes the carboxylate and methyl groups of aldobiouronic acid as important substrate recognition determinants.

alpha-Glucuronidases are key components of the ensemble of enzymes that degrade the plant cell wall. They hydrolyze the alpha1,2-glycosidic bond between 4-O-methyl-d-glucuronic acid (4-O-MeGlcA) and the xylan or xylooligosaccharide backbone. Here we report the crystal structure of an inactive mutant (E292A) of the alpha-glucuronidase, GlcA67A, from Cellvibrio japonicus in complex with its substrate.

Water use by forests, limits and controls.

Based on a review of several studies that have been carried out to determine the water use of forests in relation to other crops in different regions of the world, it is shown that the principal controls on evaporation from forests and shorter crops vary markedly between the temperate and tropical regions and between the wet and dry zones of these regions. Although there are detailed physical and physiological models available that allow calculation of forest water use, these models are not always readily applicable. It is proposed that a knowledge of the limits on evaporation can be used to devise models of varying complexity for estimating water use of forests in different regions and for predicting differences in water use between forests and shorter crops.

Characterisation of the DNA-dependent ATPase activity of human DNA topoisomerase IIbeta: mutation of Ser165 in the ATPase domain reduces the ATPase activity and abolishes the in vivo complementation ability.

We report for the first time an analysis of the ATPase activity of human DNA topoisomerase (topo) IIbeta. We show that topo IIbeta is a DNA-dependent ATPase that appears to fit Michaelis-Menten kinetics. The ATPase activity is stimulated 44-fold by DNA.

Can mitochondrial DNA mutations cause sperm dysfunction?

Very low levels of somatic mitochondrial (mt)DNA deletions have been identified in the semen of infertile men. It has been suggested that these mutations cause infertility through an effect on sperm motility, but there has been no direct evidence to show that mutant mtDNA can affect sperm function. We have carried out semen analysis on a male harbouring the A3243G mtDNA mutation and show that high levels of mutant mtDNA strongly correlate with low sperm motility.

Ppm1, a novel polyprenol monophosphomannose synthase from Mycobacterium tuberculosis.

Dolichol monophosphomannose (DPM) is an ever-present donor of mannose (Man) in various eukaryotic glycosylation processes. Intriguingly, the related polyprenol monophosphomannose (PPM) is involved in the biosynthesis of lipomannan and lipoarabinomanan, key bacterial factors termed modulins that are found in mycobacteria. Based on similarities to known DPM synthases, we have identified and characterized the PPM synthase of Mycobacterium tuberculosis, now termed Mt-Ppm1.

Purification and biochemical characterization of Mycobacterium tuberculosis SuhB, an inositol monophosphatase involved in inositol biosynthesis.

Phosphatidylinositol is an essential component of mycobacteria, and phosphatidylinositol-based lipids such as phosphatidylinositolmannosides, lipomannan, and lipoarabinomannan are major immunomodulatory components of the Mycobacterium tuberculosis cell wall. Inositol monophosphatase (EC 3.1.

Late-onset axial jerky dystonia due to the DYT1 deletion.

We describe a 71-year-old woman who presented to the neurology department late in life with a jerky axial dystonia due to the DYT1 GAG deletion. She recalled that her symptoms began 62 years prior to study and remained unchanged for 40 years, illustrating the broad phenotype of DYT1 idiopathic torsion dystonia.

Structure of a family 15 carbohydrate-binding module in complex with xylopentaose. Evidence that xylan binds in an approximate 3-fold helical conformation.

The recycling of photosynthetically fixed carbon by the action of microbial glycoside hydrolases is a key biological process. The consortium of degradative enzymes involved in this process frequently display catalytic modules appended to one or more noncatalytic carbohydrate-binding modules (CBMs). CBMs play a central role in the optimization of the catalytic activity of plant cell wall hydrolases through their binding to specific plant structural polysaccharides.

In vitro and in vivo properties of novel nucleoside transport inhibitors with improved pharmacological properties that potentiate antifolate activity.

The activity of antimetabolite inhibitors of de novo deoxyribonucleotide biosynthesis can be compromised by the salvage of extracellular preformed nucleosides and nucleobases. Dipyridamole (DP) is a nucleoside transport inhibitor that has been used clinically in an attempt to increase antimetabolite activity; however, DP binds tightly to the serum protein alpha1-acid glycoprotein (AGP) thereby rendering this therapeutic strategy largely ineffective. Four novel DP analogues (NU3076, NU3084, NU3108, and NU3121) have been developed with substitutions at the 2,6- and 4,8-positions of the pyrimidopyrimidine ring.

Influence of the aglycone region of the substrate binding cleft of Pseudomonas xylanase 10A on catalysis.

Pseudomonas cellulosa xylanase 10A (Pc Xyn10A) contains an extended substrate binding cleft comprising three glycone (-1 to -3) and four aglycone (+1 to +4) subsites and, typical of retaining glycoside hydrolases, exhibits transglycosylation activity at elevated substrate concentrations. In a previous study [Charnock, S. J.

No correlation between muscle A3243G mutation load and mitochondrial function in vivo.

The authors studied the relationship between the percentage level of A3243G mitochondrial DNA mutation and the degree of mitochondrial dysfunction in vivo in nine individuals from four pedigrees using phosphorus MRS in muscle. There was no significant correlation between mutation load and maximum rate of adenosine triphosphate production (V(max)). V(max) was normal in a subject with 32% A3243G in muscle, which is in contrast with a previous observation of markedly reduced V(max) in a patient with only 6% A3243G in muscle.

A novel autosomal dominant distal myopathy with early respiratory failure: clinico-pathologic characteristics and exclusion of linkage to candidate genetic loci.

We describe a novel autosomal dominant myopathy presenting in mid-adult life with tibialis anterior weakness. We carried out a detailed clinical assessment of 24 individuals spanning three generations, documenting pathologic features of the muscles in 7 of the 11 affected individuals, including an autopsy study on one case. The second generation of affected individuals presented at an earlier age, and the disease progressed more rapidly than in the first generation.

Random intracellular drift explains the clonal expansion of mitochondrial DNA mutations with age.

Human tissues acquire somatic mitochondrial DNA (mtDNA) mutations with age. Very high levels of specific mtDNA mutations accumulate within individual cells, causing a defect of mitochondrial oxidative metabolism. This is a fundamental property of nondividing tissues, but it is not known how it comes about.

Leber hereditary optic neuropathy: Does heteroplasmy influence the inheritance and expression of the G11778A mitochondrial DNA mutation?

Leber hereditary optic neuropathy (LHON) is a major cause of inherited blindness in young males. Approximately 1 in 7 individuals with LHON harbor a mixture of mutated and wild-type (normal) mtDNA (heteroplasmy), and the risks of developing blindness in heteroplasmic LHON individuals are not well characterized. MtDNA is inherited exclusively down the maternal line, and although the risks of a relative within a homoplasmic LHON pedigree are relatively well established, the risks of transmission in heteroplasmic LHON pedigrees have not been studied in detail.

Freezing of barley studied by infrared video thermography.

Freezing of barley (Hordeum vulgare), Hordeum murinum, and Holcus lanatus was studied using infrared video thermography. In the field, ice could enter H. lanatus leaves through hydathodes.

The mitochondrial ND6 gene is a hot spot for mutations that cause Leber's hereditary optic neuropathy.

Leber's hereditary optic neuropathy (LHON) is a common cause of bilateral optic nerve disease. The majority of LHON patients harbour one of three point mutations of the mitochondrial DNA (mtDNA) complex I, or NADH:ubiquinone oxidoreductase (ND) genes (G11778A in ND4, G3460A in ND1, T14484C in ND6). As a consequence, screening for these mutations has become part of the routine clinical investigation of young adults who present with bilateral optic neuropathy, and the absence of these mutations is interpreted as indicating there is a low likelihood that an optic neuropathy is LHON.

Random genetic drift determines the level of mutant mtDNA in human primary oocytes.

We measured the proportion of mutant mtDNA (mutation load) in 82 primary oocytes from a woman who harbored the A3243G mtDNA mutation. The frequency distribution of mutation load indicates that random drift is the principal mechanism that determines the level of mutant mtDNA within individual oocytes.

Systematic process and outcome evaluation of brief staff training in psychosocial interventions for severe mental illness.

This study evaluated systematically the integrity and effectiveness of a topical staff training programme. The integrity of the training was evaluated in terms of its adherence to the trainer's protocol, using an observational instrument. To assess effectiveness, multiple measures of learner satisfaction, learning, generalisation and impact were administered longitudinally to N = 45 multi-disciplinary mental health professionals in the UK.

Mitochondrial DNA mutations in the pathogenesis of human disease.

The coding sequence for the human mitochondrial genome (mtDNA) was published in 1981. Within a decade, the first pathogenic mtDNA mutations were described in humans with sporadic and maternally inherited disease. The last ten years has seen a profusion of reports describing new pathogenic mutations associated with a diverse range of clinical phenotypes.

The epidemiology of pathogenic mitochondrial DNA mutations.

During the past decade, there have been many descriptions of patients with neurological disorders due to mitochondrial DNA (mtDNA) mutations, but the extent and spectrum of mtDNA disease in the general population have not yet been defined. Adults with suspected mtDNA disease in the North East of England were referred to a single neurology center for investigation over the 10-year period from 1990 to 1999 inclusive. We defined the genetic defect in these individuals.

Primary sequence and enzymic properties of two modular endoglucanases, Cel5A and Cel45A, from the anaerobic fungus Piromyces equi.

Two endoglucanase cDNAs, designated cel5A and cel45A, were isolated from a cDNA library of the anaerobic fungus Piromyces equi. Sequence analysis revealed that cel5A has an open reading frame of 5142 bp and encodes a 1714 amino acid modular enzyme, Cel5A, with a molecular mass of 194847 Da. Cel5A consists of four catalytic domains homologous to family-5 glycosyl hydrolases, two C-terminal dockerins and one N-terminal dockerin.