Reduction of antibiotics sales and sustained low incidence of bacterial resistance: Report on a broad approach during 10 years to implement evidence-based indications for antibiotic prescribing in Jönköping County, Sweden

BACKGROUND

Increased prevalence of resistance in major pathogens decreases the possibility to treat common infectious conditions. In the beginning of the 1990s, resistant pneumococci spread among children in southern Sweden, which alarmed both the profession and the medical authorities. We describe the measures taken to curb the spread of resistance and to reduce the use of antibiotics in outpatient care.

METHOD

A national organization, Strama (Swedish Strategic Programme for the Rational Use of Antimicrobial Agents and Surveillance of Resistance), was initiated in 1994 and a regional committee was formed in Jönköping County in 1995. A multifaceted program was started aiming at reducing antibiotic use in the county by 25% and that the prevalence of resistant pneumococci should not increase.

RESULTS

The efforts by the Jönköping County committee has resulted in a 31% total reduction of the consumption of antibiotic drugs in primary care between 1993 and 2005 and a 50% reduction among children aged 0 to 4 years. There has been no increase in the prevalence of resistant pneumococci or Haemophilus influenzae in the county. The decrease in antibiotic use was greater than the average in Sweden.

CONCLUSION

Our regional efforts have been successful. This has probably been achieved by a sustained strategy including repeated campaigns in the media, information to the profession, implementation of guidelines, and feedback to the profession on data on antibiotic prescribing and resistance. We believe it is of outmost importance not only to inform the profession but also the public on the limited effects of antibiotics in most respiratory tract infections.

Application of skinned single muscle fibres to determine myofilament function in ageing and disease

The chemically skinned fibre is a suitable preparation to determine whether alterations in myofilament function contribute to muscle dysfunction during ageing and disorders such as chronic obstructive pulmonary disease (COPD). In this preparation the sarcolemma is chemically permeabilized and the myofilament lattice kept intact, functioning under controlled near-physiological conditions. As force generating capacity is an important determinant of muscle function and is related to fibre crosssectional area (FCSA), we compared several methods employed by researchers to determine FCSA. Specific tension, force divided by FCSA, has a co-efficient of variation of 27%, 37%, or 30% when the FCSA was measured from the width and depth assuming an elliptical circumference, the width assuming a circular circumference, and the width while the fibre was suspended in the air, respectively. The last method showed the closest relation with the FCSA in histological sections. The velocity of maximal unloaded shortening (V(0)) varied with fibre type, with fibres expressing the Beta/slow (type I) myosin heavy chain (MyHC) isoform being the slowest and fibres expressing the IIb MyHC isoform the fastest. While muscle weakness experienced after surgery could not be explained by changes in specific tension or FCSA of individual fibres, the preparation revealed significant changes in myofilament function during ageing and COPD.

A porcine model of acute quadriplegic myopathy: a feasibility study

BACKGROUND

The mechanisms underlying acute quadriplegic myopathy (AQM) are poorly understood, partly as a result of the fact that patients are generally diagnosed at a late stage of the disease. Accordingly, there is a need for relevant experimental animal models aimed at identifying underlying mechanisms.

METHODS

Pigs were mechanically ventilated and exposed to various combinations of agents, i.e. pharmacological neuromuscular blockade, corticosteroids and/or sepsis, for a period of 5 days. Electromyography and myofibrillar protein and mRNA expression were analysed using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), confocal microscopy, histochemistry and real-time polymerase chain reaction (PCR).

RESULTS

A decreased compound muscle action potential, normal motor nerve conduction velocities, and intact sensory nerve function were observed. Messenger RNA expression, determined by real-time PCR, of the myofibrillar proteins myosin and actin decreased in spinal and cranial nerve innervated muscles, suggesting that the loss of myosin observed in AQM patients is not solely the result of myofibrillar protein degradation.

CONCLUSION

The present porcine AQM model demonstrated findings largely in accordance with results previously reported in patients and offers a feasible approach to future mechanistic studies aimed at identifying underlying mechanisms and developing improved diagnostic tests and intervention strategies.

Muscle cell and motor protein function in patients with a IIa myosin missense mutation (Glu-706 to Lys)

The pathogenic events leading to the progressive muscle weakness in patients with a E706K mutation in the head of the myosin heavy chain (MyHC) IIa were analyzed at the muscle cell and motor protein levels. Contractile properties were measured in single muscle fiber segments using the skinned fiber preparation and a single muscle fiber in vitro motility assay. A dramatic impairment in the function of the IIa MyHC isoform was observed at the motor protein level. At the single muscle fiber level, on the other hand, a general decrease was observed in the number of preparations where the specific criteria for acceptance were fulfilled irrespective of MyHC isoform expression. Our results provide evidence that the pathogenesis of the MyHC IIa E706K myopathy involves defective function of the mutated myosin as well as alterations in the structural integrity of all muscle cells irrespective of MyHC isoform expression.

Impact of post-synaptic block of neuromuscular transmission, muscle unloading and mechanical ventilation on skeletal muscle protein and mRNA expression

To analyse mechanisms of muscle wasting in intensive care unit patients, we developed an experimental model where rats were pharmacologically paralysed by post-synaptic block of neuromuscular transmission (NMB) and mechanically ventilated for 9+/-2 days. Specific interest was focused on the effects on protein and mRNA expression of sarcomeric proteins, i.e., myosin heavy chain (MyHC), actin, myosin-binding protein C (MyBP-C) and myosin-binding protein H (MyBP-H) in fast- and slow-twitch limb, respiratory and masticatory muscles. Muscle-specific differences were observed in response to NMB at both the protein and mRNA levels. At the protein level, a decreased MyHC-to-actin ratio was observed in all muscles excluding the diaphragm, whereas at the mRNA level a decreased expression of the dominating MyHC isoform(s) was observed in the hind limb and intercostal muscles, but not in the diaphragm and masseter muscles. MyBP-C mRNA expression was decreased in the limb muscles, but it otherwise remained unaffected. MyBP-H conversely increased in all muscles. Furthermore, we found myofibrillar protein and mRNA expression to be affected differently when comparing NMB animals with peripherally denervated (DEN) ambulatory rats. We report that NMB has both a larger and different impact on muscle, at the protein and mRNA levels, than DEN has.

Human skeletal muscle myosin function at physiological and non-physiological temperatures

AIM

The aim of the study was to assess the function of human skeletal muscle myosin across a wide range of temperatures, including physiological.

METHODS

We used a single fibre in vitro motility assay. The in vitro motility speed of actin filaments propelled by myosin extracted from fibres expressing type I myosin heavy chain (MyHC; n = 9), IIa MyHC (n = 6), IIax MyHC (n = 4) and I/IIa MyHC (n = 1) was measured at 15, 20, 25, 30 and 35 degrees C.

RESULTS

The motility speed between groups of fibres expressing different MyHC differed significantly (P << 0.001). The increase in motility speed with an increase in temperature was statistically significant (P << 0.001) between all temperatures. The relative difference in motility speed between the slow type I and the fast IIax MyHC fibres decreased with increasing temperature, i.e. a 7.5-fold difference at 15 degrees C was reduced to twofold at 35 degrees C. Furthermore, the twofold difference in motility speed between type IIa and IIax MyHC at 15 degrees C disappeared completely at 35 degrees C. The activation energy, E(A), and temperature coefficient, Q(10), over the 15-35 degrees C temperature range was higher for type I MyHC, 54.47 +/- 4.37 kJ mol(-1) and 2.09 +/- 0.12, respectively, than for type IIa MyHC, 45.41 +/- 3.12 kJ mol(-1) (P < 0.001) and 1.85 +/- 0.08 (P < 0.001), or IIax MyHC, 34.71 +/- 1.75 kJ mol(-1) (P << 0.001) and 1.60 +/- 0.04 (P << 0.001).

CONCLUSION

The present results suggest a significantly reduced difference in shortening velocity between different human muscle fibre types at physiological temperature than previously reported at lower temperatures (12 or 15 degrees C) with implications for human in vivo muscle function.

Worse survival for TP53 (p53)-mutated breast cancer patients receiving adjuvant CMF

BACKGROUND

TP53 has been described as a prognostic factor in many malignancies, including breast cancer. Whether it also might be a predictive factor with reference to chemo- and endocrine therapy is more controversial.

PATIENTS AND METHODS

We investigated relapse-free (RFS), breast cancer-corrected (BCCS) and overall survival (OS) related to TP53 status in node-positive breast cancer patients that had received polychemotherapy [cyclophosphamide, methotrexate, 5-fluorouracil (CMF)] and/or endocrine therapy (tamoxifen). Sequence analyses of the whole TP53 coding region was performed in 376 patients operated on for primary breast cancer with axillary lymph node metastases between 1984 and 1989 (median follow-up time 84 months).

RESULTS

TP53 mutations were found in 105 patients (28%). We found 90 (82%) of the 110 mutations in the more frequently analysed exons 5-8, while the other 20 (18%) were located in exons 3-4 and 9-10, respectively. Univariate analyses showed TP53 to be a significant prognostic factor with regard to RFS, BCCS and OS in patients who received adjuvant CMF.

CONCLUSIONS

TP53 mutations might induce resistance to certain modalities of breast cancer therapy. Sequence-determined TP53 mutation was of negative prognostic value in the total patient population and in the CMF treated patients.

Genetic determinants of weight of fast- and slow-twitch skeletal muscle in 500-day-old mice of the C57BL/6J and DBA/2J lineage

C57BL/6J (B6) and DBA/2J (D2) strains and two derivative populations, BXD recombinant inbred strains (BXD RIs) and B6D2F2, were used to explore genetic basis for variation in muscle weight at 500 days of age. In parallel with findings in 200-day-old mice (Lionikas A, Blizard DA, Vandenbergh DJ, Glover MG, Stout JT, Vogler GP, McClearn GE, and Larsson L. Physiol Genomics 16: 141-152, 2003), weight of slow-twitch soleus, mixed gastrocnemius, and fast-twitch tibialis anterior (TA) and extensor digitorum longus (EDL) muscles was 13-22% greater (P < 0.001) in B6 than in D2. Distribution of BXD RI strain means indicated that genetic influence on muscle weight (strain effect P < 0.001, all muscles) was of polygenic origin, and effect of genetic factors differed between males and females (strain-by-sex interaction: P < 0.01 for soleus, EDL; P < 0.05 for TA, gastrocnemius). Linkage analyses in B6D2F2 population identified QTL affecting muscle weight on Chr 1, 2, 6, and 9. Pleiotropic influences were observed for QTL on Chr 1 (soleus, TA), 2 (TA, EDL, gastrocnemius), and 9 (soleus, TA, EDL) and were not related to muscle type (fast/slow-twitch) or function (flexor/extensor). Effect of QTL on Chr 9 on soleus muscle was male specific. QTL on Chr 2 and 6 were previously observed at 200 days of age, whereas QTL on Chr 1 and 9 are novel muscle weight QTL. In summary, muscle weight in B6/D2 lineage is affected by a polygenic system that has variable influences at different ages, between males and females, and across muscles in a manner independent of muscle type.

Determination of microbial volatile organic compounds adsorbed on house dust particles and gypsum board using SPME/GC-MS

Adsorption of microbial volatile organic compounds (MVOCs) on house dust was analyzed by performing solid phase microextraction (SPME) in combination with gas chromatography-mass spectrometry (GC-MS). Settled dust samples were exposed to five selected MVOCs and to cultures of the molds Stachybotrus chartarum, Aspergillus versicolor, and Chaetomium globosum. Considerable desorption of the MVOCs adsorbed on the dust occurred spontaneously within a few hours at room temperature and within several days or weeks after storage at -20 degrees or -80 degrees C. Similar results were found for a sample of a gypsum board cultivated with A. versicolor. SPME/GC-MS analysis performed immediately after sampling revealed several of the studied MVOCs on gypsum board and settled dust collected in a house garage with visible mold growth. MVOCs adsorbed on respirable particles of house dust can be inhaled and reach deep into the respiratory system, which may partly explain health effects that have been found to be associated with the presence of low concentrations of MVOCs in air. Particle-bound MVOCs can easily be detected by SPME/GC-MS analysis, thus this technique may prove to be very useful in indoor air research for identifying factors that affect human health.

PRACTICAL IMPLICATIONS

We used SPME combined with GC-MS to study the adsorption and desorption of MVOCs on house dust particles that had been exposed to cultivated molds and molds in a damp building. Adsorbed MVOCs desorb spontaneously but this process can be slowed down by storing samples at -20 degrees or -80 degrees C. This opens up a possibility to apply SPME/GC-MS to reveal mold growth in buildings and to determine MVOCs in respirable dust particles that may reach deep in the respiratory system and lead to respiratory illnesses.

Characterization of the microbial community in indoor environments by chemical marker analysis: an update and critical evaluation

We published recently an integrated procedure for applying chemical marker analysis to characterize the microbiology of indoor environments comprising a scheme for extraction and analysis of markers of endotoxin, peptidoglycan/bacterial biomass, and fungal biomass. In the present paper, we report some significant improvements and also new possibilities of the described approach. We found that while 3-hydroxy fatty acids (3-OH FAs) of 10-14 carbon chain lengths are useful endotoxin markers, longer 3-OH FAs (i.e. with 16 carbon atoms and more) may rather serve as markers of Actinobacteria. We introduced 13C-labeled 3-hydroxytridecanoic acid, from labeled Pectinatus cerevisiiphilus, as an internal standard to improve quantification of the 3-OH FAs in the gas chromatography-mass spectrometry analysis. Finally, in experiments aiming to identify a suitable method for collection of house dust for chemical marker analysis, we found that the marker compositions of dusts sedimented on plexiglass plates that were spatially well-distributed in a studied room at different heights above floor level, were undistinguishable. This type of sampling thus appears to be well suited for use, e.g. in epidemiological studies. In summary, the presented work describes important new capabilities of chemical marker analysis in defining human exposure to microorganisms in indoor environments.

PRACTICAL IMPLICATIONS

We are developing an integrated methodology for characterizing the microbiology of indoor environments where specific microbial monomeric constituents in building materials and inhalable house dust particles are determined by using mass spectrometry-based methods. The methodology should represent a firm basis in research aiming to relate microbial exposure indoors to well-being and health.

Tobacco smoking increases dramatically air concentrations of endotoxin

We used a mass spectrometry-based assay for identifying the endotoxin (lipopolysaccharide, LPS) marker (R)-3-hydroxytetradecanoic acid in cigarette smoke particles and found that smoking involved inhalation of 17.4 pmol of endotoxin per each smoked cigarette. Indoor exposure to environmental tobacco smoke (ETS) entailed inhalation of 12.1 pmol of LPS/m3 air, an amount that was 120 times higher than the levels found in smoke-free indoor air. Endotoxin is one of the most potent inflammatory agents known, hence our results may help to explain the high prevalence of respiratory disorders among smokers, and they may also draw attention to a hitherto unknown or neglected risk factor of ETS.

PRACTICAL IMPLICATIONS

Endotoxin represents a largely neglected risk factor of smoking and passive smoking and this knowledge may lead to a reduced smoking.

Aberrant expression of myosin isoforms in skeletal muscles from mice lacking the rev-erbAalpha orphan receptor gene

The rev-erbAalpha orphan protein belongs to the steroid nuclear receptor superfamily. No ligand has been identified for this protein, and little is known of its function in development or physiology. In this study, we focus on 1) the distribution of the rev-erbAalpha protein in adult fast- and slow-twitch skeletal muscles and muscle fibers and 2) how the rev-erbAalpha protein influences myosin heavy chain (MyHC) isoform expression in mice heterozygous (+/-) and homozygous (-/-) for a rev-erbAalpha protein null allele. In the fast-twitch extensor digitorum longus muscle, rev-erbAalpha protein expression was linked to muscle fiber type; however, MyHC isoform expression did not differ between wild-type, +/-, or -/- mice. In the slow-twitch soleus muscle, the link between rev-erbAalpha protein and MyHC isoform expression was more complex than in the extensor digitorum longus. Here, a significantly higher relative amount of the beta/slow (type I) MyHC isoform was observed in both rev-erbAalpha -/- and +/- mice vs. that shown in wild-type controls. A role for the ratio of thyroid hormone receptor proteins alpha1 to alpha2 in modulating MyHC isoform expression can be ruled out because no differences were seen in MyHC isoform expression between thyroid hormone receptor alpha2-deficient mice (heterozygous and homozygous) and wild-type mice. Therefore, our data are compatible with the rev-erbAalpha protein playing an important role in the regulation of skeletal muscle MyHC isoform expression.

Microbial Dustiness and Particle Release of Different Biofuels

Exposure to organic dust originating from biofuels can cause adverse health effects. In the present study we have assessed the dustiness in terms of microbial components and particles of various biofuels by using a rotating drum as a dust generator. Microbial components from straw, wood chips, wood pellets and wood briquettes were quantified by several methods. Excellent correlations (r >/= 0.85, P < 0.0001) were found: between lipopolysaccharide (LPS) (as determined by 3-hydroxy fatty acid analysis) and endotoxin (as determined by a Limulus test), cultivable bacteria, total number of bacteria and muramic acid; between endotoxin and cultivable bacteria, total number of bacteria and muramic acid; between total number of bacteria and muramic acid; between cultivable fungi and total number of fungi. Straw was dustier than the other biofuels in terms of actinomycetes, bacteria, muramic acid, endotoxin, LPS, particle mass and number of particles. One of the wood chips studied and the straws had comparatively high dustiness in terms of fungi, while both wood pellets and wood briquettes had comparatively low dustiness in terms of all microbial components. An initially high particle generation rate of straw and wood chips decreased over time whereas the particle generation rate of wood briquettes and wood pellets increased during a 5 min rotation period. Particles of non-microbial origin may be the determining factor for the health risk in handling briquettes and pellets. Straw dust contained significantly more microorganisms per particle than did wood chip dust, probably because bacteria were most abundant in straw dust. The concentrations of endotoxin and fungi were high in wood and straw dust; dust from one of the straws contained 3610 EU/mg and dust from one of the chips contained 7.3 x 10(6) fungal spores/mg. An exposure to 3 mg of straw or wood chips dust/m(3) (the Swedish and Danish OEL of unspecific inhalable dust) could cause exposures to endotoxin and fungi higher than levels were health symptoms are seen to develop. The very different levels of dustiness in terms of particles and microbial components of different biofuels shows that dustiness is an important health-relevant factor to consider when choosing among biofuels and when designing worksites for handling of biofuels.

Evidence-based strategies for preventing drug administration errors during anaesthesia

We developed evidence-based recommendations for the minimisation of errors in intravenous drug administration in anaesthesia from a systematic review of the literature that identified 98 relevant references (14 with experimental designs or incident reports and 19 with reports of cases or case series). We validated the recommendations using reports of drug errors collected in a previous study. One general and five specific strong recommendations were generated: systematic countermeasures should be used to decrease the number of drug administration errors in anaesthesia; the label on any drug ampoule or syringe should be read carefully before a drug is drawn up or injected; the legibility and contents of labels on ampoules and syringes should be optimised according to agreed standards; syringes should (almost) always be labelled; formal organisation of drug drawers and workspaces should be used; labels should be checked with a second person or a device before a drug is drawn up or administered.

Microorganisms and volatile organic compounds in airborne dust from damp residences

Airborne dust samples from damp (n = 9) and control (n = 9) residences were analyzed for microorganisms (molds and bacteria), bacterial markers (3-hydroxy fatty acids and muramic acid), and adsorbed volatile organic compounds (VOCs). The number of mold species was greater in the damp residences than in the controls (23 vs.18) and nine mold species were found only in damp residences. The levels of 3-hydroxy fatty acids and muramic acid correlated better in damp residences than in controls, indicating that damp conditions affect the bacterial flora of airborne dust. Identifications made by culture and microscopy of the major molds found, i.e. Aspergillus, Cladosporium, and Penicillum, coincided with the identification of VOCs known to be produced by these species. A number of additional VOCs irritating to the skin, eyes, or respiratory tract were also found. The results from this pilot study illustrate the diversity of microorganisms and VOCs present in the indoor environment and suggest that analysis of airborne dust may help to assess human exposure to microorganisms and chemical compounds.

Genetic architecture of fast- and slow-twitch skeletal muscle weight in 200-day-old mice of the C57BL/6J and DBA/2J lineage

The aim of the study was to explore the genetic architecture influencing weight of fast- and slow-twitch skeletal muscles. The weights of the slow-twitch soleus, the mixed gastrocnemius, the fast-twitch tibialis anterior (TA), and extensor digitorum longus (EDL) muscles were 11-34% greater (P < 0.001) in 200-day-old C57BL/6J (B6) than in DBA/2J (D2) mice. Male muscles were 13-28% larger than female (P < 1 x 10(-5), no strain by sex interaction). The sex-related difference in muscle weight, however, varied significantly among the 23 derivative BXD recombinant inbred (RI) strains (strain by sex interaction for soleus, P < 0.01; TA, P < 1 x 10(-4); EDL, not significant; and gastrocnemius, P < 0.001). Quantitative trait loci (QTL) affecting muscle weight were mapped in an F2 intercross of B6 and D2 mice (B6D2F2) and BXD RIs. A total of 10 autosomal, muscle-specific, but not muscle-type-specific, QTL, explaining a total of 5.4, 7.7, 22.9, and 8.6% of phenotypic variance for soleus, TA, EDL, and gastrocnemius muscles, respectively, were found across chromosomes 1 (Chr 1), 2, 3 (female-specific), 5 (two), 6, 7, 8, and 9 in B6D2F2 mice. The QTL on Chr 8 for EDL and the female-specific QTL on Chr 3 for gastrocnemius muscles were statistically significant, but the remaining QTL were at the suggestive level of statistical significance. Ten QTL on Chr 1, 2, 4, 5, 7, 8, 14, 17 (two), and 19 were identified in BXD RIs. Half of the QTL in BXD RIs had pleiotropic effects and were at the suggestive level of significance (except for the significant QTL for gastrocnemius muscle on Chr 17). The B6D2F2 nominated QTL on Chr 8 for EDL weight was validated in BXD RIs (P < 0.03). Support intervals for the QTL on Chr 1 and 5 overlapped between B6D2F2 and BXD RIs. An epistatic interaction between markers on Chr 1 and 17 affected gastrocnemius weight in BXD RIs. The interaction was not, however, validated in the B6D2F2 population. Our results indicate that the differences in muscle weight in the B6 and D2 segregating populations were the outcome of a polygenic system, with each factor contributing a small amount to the phenotypic variance and the genetic architecture affecting muscle weight was muscle specific, but not muscle-type specific, and in some instances sex specific.

Interventional treatment of children with portal hypertension secondary to portal vein occlusion

PURPOSE

To present methods and results of interventional treatment of children with portal hypertension (PH) secondary to portal vein occlusion (PVO).

MATERIAL AND METHODS

Five children, four boys and one girl, 8 - 14 years old, with symptomatic PH secondary to PVO were treated. All children had one or more episodes of bleeding from oesophageal varices, enlarged spleen and thrombocytopenia. Partial embolisation of the spleen was performed in four children. Attempts to recanalize the occluded part of the portal vein were done in all children using transjugular (n = 4), transhepatic (n = 4) and transsplenic (n = 3) approaches.

RESULTS

All procedures were carried out without serious complications and were followed by normalisation of the platelet count, decrease in splenic size and disappearance of bleeding. Recanalisation of the occluded portal vein with a stent was possible in one child and partial stent recanalisation was possible in another child. Transjugular intrahepatic portosystemic shunt (TIPS) with partly extrahepatic, intraperitoneal route was created in one patient. All children were scheduled for follow-up. During the observation time of 22 months (5 - 46 months), additional balloon dilation and placement of new stents were necessary in two children.

CONCLUSION

Interventional procedures are valuable in the treatment of children with symptoms secondary to PVO. Treatment should be customized and scheduled follow-ups of the patients are necessary.

Human single masseter muscle fibers contain unique combinations of myosin and myosin binding protein C isoforms

Striated craniofacial and limb muscles differ in their embryological origin, regulatory program during myogenesis, and innervation. In an attempt to explore the effects of these differences on the striated muscle phenotype in humans, the expression of myosin and myosin-associated thick filament proteins were studied at the single fiber level both in the human jaw-closing masseter muscle and in two limb muscles (biceps brachii and quadriceps femoris muscles). In the masseter, unique combinations of myosin heavy chain (MyHC) and myosin binding protein C (MyBP-C) isoforms were observed at the single fiber level. Compared to the limb muscles, the MyHC isoform expression was more complex in the masseter while the opposite was observed for MyBP-C. In limb muscles, a coordinated expression of three MyHC and three MyBP-C isoforms were observed, i.e., single fibers contained one or two MyHC isoforms, and up to three MyBP-C isoforms. Also, the relative content of the different MyBP-C isoforms correlated with the MyHC isoform expression. In the masseter, on the other hand, up to five different MyHC isoforms could be observed in the same fiber, but only one MyBP-C isoform was identified irrespective MyHC isoform expression. This MyBP-C isoform had a migration rate similar to the slow MyBP-C isoform in limb muscle fibers. In conclusion, a unique myofibrillar protein isoform expression was observed in the human masseter muscle fibers, suggesting significant differences in structural and functional properties between muscle fibers from human masseter and limb muscles.

Glutathione reverses early effects of glycation on myosin function

Nonenzymatic glycosylation (glycation) has been recognized as an important posttranslational modification underlying alterations of structure and function of extracellular proteins during aging and diabetes. Intracellular proteins may also be affected by this modification, and glycation has been suggested to contribute to aging-related impairment in skeletal muscle function. Glycation is the chemical reaction of reducing sugars with primary amino groups resulting in the formation of irreversible advanced glycation end products. Glutathione is an abundant tripeptide in skeletal muscle. To understand the effect of glutathione on glycated myosin function, we used a single-fiber in vitro motility assay in which myosin is extracted from a single muscle fiber segment to propel fluorescent-labeled actin filaments. Myosin function responded to glucose exposure in a dose-dependent manner, i.e., motility speeds were reduced by 10, 34, and 90% of preincubation values after 30-min exposure to 1, 3, and 6 mM glucose, respectively. The 30-min 6 mM glucose incubation was followed by a 20-min 10 mM glutathione incubation. Glutathione treatment restored motility (0.98 +/- 0.06 microm/s, n = 3; P < 0.001) after glucose exposure (0.10 +/- 0.07 microm/s, n = 3), close to preincubation levels (1.12 +/- 0.06 microm/s, n = 3). It is concluded that glucose modifies myosin function in a dose-dependent manner and that glutathione reverses the effect of glucose on myosin function.

The prevalence of frontal variant frontotemporal dementia and the frontal lobe syndrome in a population based sample of 85 year olds

OBJECTIVES

To investigate the prevalence of the frontal lobe syndrome (FLS) and the frontal variant of frontotemporal dementia (fvFTD) in a population based sample of 85 year olds.

METHODS

A representative sample of 85 year olds (n = 451) in Gothenburg, Sweden was examined with a neuropsychiatric examination and a key informant interview performed by an experienced psychiatrist. A subsample underwent computed tomography (CT) of the head. The Lund-Manchester research criteria were used as a basis for a symptom algorithm to identify individuals with FLS and fvFTD. These were diagnosed blindly to the diagnosis of dementia according to DSM-III-R.

RESULTS

A total of 86 individuals (19%) fulfilled the criteria for FLS, and 14 of them fulfilled criteria for fvFTD. There were no differences between men and women. Among those with FLS, 75 (87%) fulfilled DSM-III-R criteria for other types of dementia, mainly Alzheimer's disease and vascular dementia. Among the 14 fvFTD cases, only five were demented according to DSM-III-R. Moderate to severe frontal atrophy was found in 93% of those with FLS (and in all cases with fvFTD), but also in 49% of those without FLS. FLS was found in 35% of those with moderate to severe frontal atrophy, and in 3% of those without these changes.

CONCLUSIONS

The prevalence of fvFTD was 3% in 85 year olds, which is higher than previously expected in this age group. Only a minority of those with fvFTD were detected by the DSM-III-R criteria for dementia. FLS was even more common, especially in those diagnosed with a dementia disorder.