Dimensional crossover and weak localization in a 90 nm n-GaAs thin film

We report on the magnetotransport in a 90 nm thick n-type GaAs epitaxial thin film in the weak localization (WL) regime. Low temperature (T</=50 K) magnetotransport data are fit with WL theory, from which the phase coherence time, tau(varphi) proportional, variantT(-p) (p=1.22+/-0.01), are extracted. We conclude that the dominant dephasing mechanism at these temperatures is electron-electron (e-e) scattering in the Nyquist limit. Evidence of a crossover from two-dimensional to three-dimensional behavior with respect to both coherent transport (WL) and e-e interactions is observed in the temperature dependence of the zero-field conductivity and tau(varphi), respectively.

Electrical detection of germination of viable model Bacillus anthracis spores in microfluidic biochips

In this paper, we present a new impedance-based method to detect viable spores by electrically detecting their germination in real time within microfluidic biochips. We used Bacillus anthracis Sterne spores as the model organism. During germination, the spores release polar and ionic chemicals, such as dipicolinic acid (DPA), calcium ions, phosphate ions, and amino acids, which correspondingly increase the electrical conductivity of the medium in which the spores are suspended. We first present macro-scale measurements demonstrating that the germination of spores can be electrically detected at a concentration of 10(9) spores ml(-1) in sample volumes of 5 ml, by monitoring changes in the solution conductivity. Germination was induced by introducing an optimized germinant solution consisting of 10 mM L-alanine and 2 mM inosine. We then translated these results to a micro-fluidic biochip, which was a three-layer device: one layer of polydimethylsiloxane (PDMS) with valves, a second layer of PDMS with micro-fluidic channels and chambers, and the third layer with metal electrodes deposited on a pyrex substrate. Dielectrophoresis (DEP) was used to trap and concentrate the spores at the electrodes with greater than 90% efficiency, at a solution flow rate of 0.2 microl min(-1) with concentration factors between 107-109 spores ml(-1), from sample volumes of 1-5 microl. The spores were captured by DEP in deionized water within 1 min (total volume used ranged from 0.02 microl to 0.2 microl), and then germinant solution was introduced to the flow stream. The detection sensitivity was demonstrated to be as low as about a hundred spores in 0.1 nl, which is equivalent to a macroscale detection limit of approximately 10(9) spores ml(-1). We believe that this is the first demonstration of this application in microfluidic and BioMEMS devices.

Genomic analysis of the rhg1 locus: candidate genes that underlie soybean resistance to the cyst nematode

The rhg1 gene or genes lie at a recessive or co-dominant locus, necessary for resistance to all Hg types of the soybean (Glycine max (L.) Merr.) cyst nematode (Heterodera glycines I.). The aim here was to identify nucleotide changes within a candidate gene found at the rhg1 locus that were capable of altering resistance to Hg types 0 (race 3). A 1.5 +/- 0.25 cM region of chromosome 18 (linkage group G) was shown to encompass rhg1 using recombination events from four near isogenic line populations and nine DNA markers. The DNA markers anchored two bacterial artificial chromosome (BAC) clones 21d9 and 73p6. A single receptor like kinase (RLK; leucine rich repeat-transmembrane-protein kinase) candidate resistance gene was amplified from both BACs using redundant primers. The DNA sequence showed nine alleles of the RLK at Rhg1 in the soybean germplasm. Markers designed to detect alleles showed perfect association between allele 1 and resistance to soybean cyst nematode Hg types 0 in three segregating populations, fifteen additional selected recombination events and twenty-two Plant Introductions. A quantitative trait nucleotide (QTN) [corrected] in the RLK at rhg1 was inferred that alters A87 to V87 in the context of H274 rather than N274. [corrected] Contiguous DNA sequence of 315 kbp of chromosome 18 (about 2 cM) contained additional gene candidates that may modulate resistance to other Hg-types including a variant laccase, a hydrogen-sodium ion antiport and two proteins of unknown function. A molecular basis for recessive and co-dominant resistance that involves interactions among paralagous disease-resistance genes was inferred that would improve methods for developing new nematode-resistant soybean cultivars.

Identifying and treating patients with suboptimal responses

Multiple sclerosis (MS) is an immune-mediated neurologic disease in which acute inflammatory events early in the disease course contribute to subsequent neurologic disability. The early relapsing inflammatory phase is followed by a progressive degenerative phase in which the frequency of acute inflammatory attacks diminishes but progressive loss of neurologic function continues. Current immune therapies are most effective in suppressing the acute inflammatory events that characterize the earlier stages of disease. Optimal suppression of these inflammatory events is likely to have the best potential for delaying or preventing loss of axons and decline in neurologic function. In view of these considerations, and because MS is a heterogeneous disease and response to disease-modifying agents (DMA) varies across individuals, it is important to identify suboptimal responders as early as possible to allow therapeutic modification while the opportunity to avert future loss of function remains. At present, no criteria for identifying suboptimal responders have been validated. In January 2004, a group of neurologists from 16 MS centers in the United States met to develop a consensus on criteria for defining suboptimal response for use in compelling clinical situations and to prompt clinical studies to validate the efficacy of these criteria. Consensus criteria included relapse rates of either 1/year or unchanged from pretreatment rates, incomplete recovery from multiple attacks, evolution of polyregional neurologic involvement, recurrent brainstem or spinal cord lesions, and cumulative loss of neurologic function sufficient to disrupt daily activities. The panel then considered the use of mitoxantrone for patients with worsening MS and a suboptimal response to DMA therapy.

Expression of cellular antigens of Listeria monocytogenes that react with monoclonal antibodies C11E9 and EM-7G1 under acid-, salt- or temperature-induced stress environments

AIMS

To study the expression of cellular antigens of Listeria monocytogenes that react with monoclonal antibodies (MAbs) C11E9 and EM-7G1 under acid-, salt- or temperature-induced stress environments.

METHODS AND RESULTS

The reaction patterns of antibodies to L. monocytogenes held in stressful environments for a short duration (3 h) or grown for extended periods (16-72 h) were investigated. During both short or prolonged exposure to stress environments of high temperature (45 degrees C) and NaCl (>1.5%, w/v), reactions of whole cells of L. monocytogenes to antibodies were severely affected as determined by ELISA and by the reduced expression of the antibody-reactive 66 kDa antigen in the Western blot assay. Conversely, cold (4-15 degrees C) or acid (pH 2-3) stress environments had very little effect on antigen expression or antibody reaction. Additionally, heat-killed cells showed reduced reactions to these antibodies when compared with unheated cells. Artificially created stress environments in hotdog slurry also affected the antigen expression in L. monocytogenes. Immunoelectron microscopy revealed that the antibody-reactive antigens were uniformly present on the surface of the cells. Morphological characteristics following growth in stressed environments revealed that heat stress at 45 degrees C caused L. monocytogenes cells to be elongated and to form clumps; whereas, osmotic stress (5.5% NaCl, w/v) caused filamentous appearance with multiple septa along the length of the cell.

CONCLUSIONS

These results indicated that MAb C11E9 or EM-7G1 could detect L. monocytogenes from cold or acid-stress environments; however, they may show weaker reactions with heat or osmotically stressed cells or cells grown at 4 degrees C.

SIGNIFICANCE AND IMPACT OF THE STUDY

Bacteria in food are routinely subjected to various stresses, induced by cold, heat, salt or acid during processing and storage. Whether stresses would modify the expression of cellular antigens of L. monocytogenes is of a great concern for immunodetections in food products.

Mutations in the fukutin-related protein gene (FKRP) identify limb girdle muscular dystrophy 2I as a milder allelic variant of congenital muscular dystrophy MDC1C

The limb girdle and congenital muscular dystrophies (LGMD and CMD) are characterized by skeletal muscle weakness and dystrophic muscle changes. The onset of symptoms in CMD is within the first few months of life, whereas in LGMD they can occur in late childhood, adolescence or adult life. We have recently demonstrated that the fukutin-related protein gene (FKRP) is mutated in a severe form of CMD (MDC1C), characterized by the inability to walk, leg muscle hypertrophy and a secondary deficiency of laminin alpha2 and alpha-dystroglycan. Both MDC1C and LGMD2I map to an identical region on chromosome 19q13.3. To investigate whether these are allelic disorders, we undertook mutation analysis of FKRP in 25 potential LGMD2I families, including some with a severe and early onset phenotype. Mutations were identified in individuals from 17 families. A variable reduction of alpha-dystroglycan expression was observed in the skeletal muscle biopsy of all individuals studied. In addition, several cases showed a deficiency of laminin alpha2 either by immunocytochemistry or western blotting. Unexpectedly, affected individuals from 15 families had an identical C826A (Leu276Ileu) mutation, including five that were homozygous for this change. Linkage analysis identified at least two possible haplotypes in linkage disequilibrium with this mutation. Patients with the C826A change had the clinically less severe LGMD2I phenotype, suggesting that this is a less disruptive FKRP mutation than those found in MDC1C. The spectrum of LGMD2I phenotypes ranged from infants with an early presentation and a Duchenne-like disease course including cardiomyopathy, to milder phenotypes compatible with a favourable long-term outcome.

Micropatterning of biomedical polymer surfaces by novel UV polymerization techniques

The "living" radical polymerization with an iniferter was used to create micropatterned biomedical surfaces. Novel, photosensitive biomedical polymers were created by the incorporation of dithiocarbamate groups from iniferters. A second monomer layer was then irradiated onto the photosensitive polymer substrate created with the iniferter to form a copolymer. Patterns were created on the films by application of modified microfabrication-based photolithographic techniques. The technique was used to create patterns with depths from 5 to 80 microm. In addition, various polymers were incorporated, including polyethylene glycol methacrylates, styrene, and methacrylic acid, to synthesize regions with different physico-chemical properties. Applications include novel surfaces for biosensors and biomaterials for the selective adhesion of cells and proteins.

Genomic organization of the dysferlin gene and novel mutations in Miyoshi myopathy

OBJECTIVE

Mutations in the skeletal muscle gene dysferlin cause two autosomal recessive forms of muscular dystrophy: Miyoshi myopathy (MM) and limb girdle muscular dystrophy type 2B (LGMD2B). The purpose of this study was to define the genomic organization of the dysferlin gene and conduct mutational screening and a survey of clinical features in 21 patients with defined molecular defects in the dysferlin gene.

METHODS

Genomic organization of the gene was determined by comparing the dysferlin cDNA and genomic sequence in P1-derived artificial chromosomes (PACs) containing the gene. Mutational screening entailed conformational analysis and sequencing of genomic DNA and cDNA. Clinical records of patients with defined dysferlin gene defects were reviewed retrospectively.

RESULTS

The dysferlin gene encompasses 55 exons spanning over 150 kb of genomic DNA. Mutational screening revealed nine novel mutations associated with MM. The range of onset in this patient group was narrow with a mean of 19.0 +/- 3.9 years.

CONCLUSION

This study confirms that the dysferlin gene is mutated in MM and LGMD2B and extends understanding of the timing of onset of the disease. Knowledge of the genomic organization of the gene will facilitate mutation detection and investigations of the molecular biologic properties of the dysferlin gene.

Adsorption of avidin on microfabricated surfaces for protein biochip applications

The adsorption of the protein avidin from hen egg white on patterns of silicon dioxide and platinum surfaces on a microchip and the use of fluorescent microscopy to detect binding of biotin are described. A silicon dioxide microchip was formed using plasma-enhanced chemical vapor deposition while platinum was deposited using radiofrequency sputtering. After cleaning using a plasma arc, the chips were placed into solutions containing avidin or bovine serum albumin. The avidin was adsorbed onto the microchips from phosphate-buffered saline (PBS) or from PBS to which ammonium sulfate had been added. Avidin was also adsorbed onto bovine serum albumin (BSA)-coated surfaces of oxide and platinum. Fluorescence microscopy was used to confirm adsorption of labeled protein, or the binding of fluorescently labeled biotin onto previously adsorbed, unlabeled avidin. When labeled biotin in PBS was presented to avidin adsorbed onto a BSA-coated microchip, the fluorescence signal was significantly higher than for avidin adsorbed onto the biochip alone. The results show that a simple, low-cost adsorption process can deposit active protein onto a chip in an approach that has potential application in the development of protein biochips for the detection of biological species.

Cloning of the mouse dysferlin gene and genomic characterization of the SJL-Dysf mutation

The SJL mouse strain has been widely used as an animal model for experimental autoimmune encephalitis (EAE), inflammatory muscle disease and lymphomas and has also been used as a background strain for the generation of animal models for a variety of diseases including motor neurone disease, multiple sclerosis and atherosclerosis. Recently the SJL mouse was shown to have myopathy due to dysferlin deficiency, so that it can now be considered a natural animal model for limb-girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM). We have cloned the mouse dysferlin cDNA and analysis of the sequence shows that the mouse dysferlin gene is characterized by six C2 domain sequences and a C-terminal anchoring domain, with the human and the mouse dysferlin genes sharing > 90% sequence homology overall. Genomic analysis of the SJL mutation confirms that the 171 bp RNA deletion has arisen by exon skipping resulting from a splice site mutation. The identification of this mutation has implications for the various groups using this widely available mouse stock.

Secondary reduction in calpain 3 expression in patients with limb girdle muscular dystrophy type 2B and Miyoshi myopathy (primary dysferlinopathies)

Dysferlin is the protein product of the gene (DYSF) that is defective in patients with limb girdle muscular dystrophy type 2B and Miyoshi myopathy. Calpain 3 is the muscle-specific member of the calcium activated neutral protease family and primary mutations in the CAPN3 gene cause limb girdle muscular dystrophy type 2A. The functions of both proteins remain speculative. Here we report a secondary reduction in calpain 3 expression in eight out of 16 patients with a primary dysferlinopathy and clinical features characteristic of limb girdle muscular dystrophy type 2B or Miyoshi myopathy. Previously CAPN3 analysis had been undertaken in three of these patients and two showed seemingly innocuous missense mutations, changing calpain 3 amino acids to those present in the sequences of calpains 1 and 2. These results suggest that there may be an association between dysferlin and calpain 3, and further analysis of both genes may elucidate a novel functional interaction. In addition, an association was found between prominent expression of smaller forms of the 80 kDa fragment of laminin alpha 2 chain (merosin) and dysferlin-deficiency.

Mutation analysis of the spastin gene (SPG4) in patients with hereditary spastic paraparesis

BACKGROUND

Hereditary spastic paraparesis is a genetically heterogeneous condition. Recently, mutations in the spastin gene were reported in families linked to the common SPG4 locus on chromosome 2p21-22.

OBJECTIVES

To study a population of patients with hereditary spastic paraparesis for mutations in the spastin gene (SPG4) on chromosome 2p21-22.

METHODS

DNA from 32 patients (12 from families known to be linked to SPG4) was analysed for mutations in the spastin gene by single strand conformational polymorphism analysis and sequencing. All patients were also examined clinically.

RESULTS

Thirteen SPG4 mutations were identified, 11 of which are novel. These mutations include missense, nonsense, frameshift, and splice site mutations, the majority of which affect the AAA cassette. We also describe a nucleotide substitution outside this conserved region which appears to behave as a recessive mutation.

CONCLUSIONS

Recurrent mutations in the spastin gene are uncommon. This reduces the ease of mutation detection as a part of the diagnostic work up of patients with hereditary spastic paraparesis. Our findings have important implications for the presumed function of spastin and schemes for mutation detection in HSP patients.

The third human FER-1-like protein is highly similar to dysferlin

Dysferlin, the protein product of the gene mutated in patients with an autosomal recessive limb-girdle muscular dystrophy type 2B (LGMD2B) and a distal muscular dystrophy, Miyoshi myopathy, is homologous to a Caenorhabditis elegans spermatogenesis factor, FER-1. Analysis of fer-1 mutants and of sequence predictions of the FER-1 and dysferlin ORFs has predicted a role in membrane fusion. Otoferlin, another human FER-1-like protein (ferlin), has recently been shown to be responsible for autosomal recessive nonsyndromic deafness (DFNB9). In this report we describe the third human ferlin gene, FER1L3, which maps to chromosome 10q23.3. Expression analysis of the orthologous mouse gene shows ubiquitous expression but predominant expression in the eye, esophagus, and salivary gland. All the ferlins are characterized by sequences corresponding to multiple C2 domains that share the highest level of homology with the C2A domain of rat synaptotagmin III. They are predicted to be Type II transmembrane proteins, with the majority of the protein facing the cytoplasm anchored by the C-terminal transmembrane domain. Sequence and predicted structural comparisons have highlighted the high degree of similarity of dysferlin and FER1L3, which have sequences corresponding to six C2 domains and which share more than 60% amino acid sequence identity.

Clinical and pathologic findings in hereditary spastic paraparesis with spastin mutation

OBJECTIVE

To describe a family with chromosome 2p-linked hereditary spastic paraparesis (HSP) associated with dementia and illustrate the cerebral pathology associated with this disorder.

BACKGROUND

HSP comprises a heterogeneous group of inherited disorders in which the main clinical feature is severe, progressive lower limb spasticity. Nongenetic classification relies on characteristics such as mode of inheritance, age at onset, and the presence or absence of additional neurologic features. Several loci have been identified for autosomal dominant pure HSP. The most common form, which links to chromosome 2p (SPG4), has recently been shown to be due to mutations in spastin, the gene encoding a novel AAA-containing protein.

RESULTS

The authors report four generations of a British family with autosomal dominant HSP in whom haplotype analysis indicates linkage to chromosome 2p. In addition, a missense mutation has been identified in exon 10 of the spastin gene (A1395G). Dementia was documented clinically in one member of the family, two other affected family members were reported to have had late onset memory loss, and a younger affected individual showed evidence of memory disturbance and learning difficulties. Autopsy of the demented patient confirmed changes in the spinal cord typical of HSP and also demonstrated specific cortical pathology. There was neuronal depletion and tau-immunoreactive neurofibrillary tangles in the hippocampus and tau-immunoreactive balloon cells were seen in the limbic and neocortex. The substantia nigra showed Lewy body formation. The pathologic findings are not typical of known tauopathies.

CONCLUSIONS

The authors confirm that chromosome 2p-linked HSP can be associated with dementia and that this phenotype may be associated with a specific and unusual cortical pathology.

Muscular dystrophy due to dysferlin deficiency in Libyan Jews. Clinical and genetic features

The cluster in Jews of Libyan origin of limb-girdle muscular dystrophy type 2B due to a dysferlin 1624delG mutation is described. The carrier frequency of this mutation is calculated to be approximately 10% in this population, in which the disease prevalence is at least 1 per 1300 adults. Twenty-nine patients from 12 families were all homozygous for the same mutation. However, clinical features were heterogeneous even within the same family: in half of the patients onset was in the distal muscles of the legs, which is similar to Miyoshi myopathy, while in others onset was in the proximal musculature, which is similar to other forms of limb-girdle dystrophies. Age at onset varied from 12 to 28 years (mean 20.3 +/- 5.5 years). One patient was presymptomatic at age 28 years. Progression was slow regardless of age of onset, patients remaining ambulatory until at least 33 years. Five patients described subacute, painful enlarged calves as an early, unusual feature. The variable features in this ethnic cluster contribute to the definition of the clinical spectrum of dysferlinopathies in general. The cause of the observed heterogeneity remains unclear.

Prediction of acute renal failure by "bedside formula" in medical and surgical intensive care patients

BACKGROUND

Prediction of which intensive care unit (ICU) patients are likely to develop acute renal failure (ARF) would be useful. However, scoring systems such as APACHE have been disappointing in this regard. We previously developed a bedside formula to predict ARF using only 3 parameters: serum albumin, urine osmolality, and presence of sepsis.

METHODS

We prospectively evaluated 115 consecutive medical ICU (MICU) patients, comparing the bedside formula to APACHE II AND APACHE III as predictors of ARF or death and looking at nutritional parameters such as iron binding capacity, triceps skin fold, mid-arm circumference, and total lymphocyte count. We then evaluated 123 additional consecutive MICU and 98 consecutive surgical ICU (SICU) patients, comparing the bedside formula to APACHE II.

RESULTS

The bedside formula was consistently more accurate than APACHE II in predicting ARF or in-hospital death in MICU patients. However, in SICU neither formula predicted ARF, and APACHE II predicted in-hospital death slightly better. No nutritional parameter other than albumin correlated with ARF.

CONCLUSION

The bedside formula appears superior to APACHE II in predicting ARF or death in MICU but not SICU. This suggests that these two ICU populations are different.

Randomized trial of a slow-release versus a standard formulation of cytarabine for the intrathecal treatment of lymphomatous meningitis

PURPOSE

To evaluate the efficacy and safety of a slow-release formulation of cytarabine (DepoCyt; Chiron Corp, Emeryville, CA, and Skye Pharma, Inc, San Diego, CA) that maintains cytotoxic concentrations of cytarabine (ara-C) in the CSF of most patients for more than 14 days.

PATIENTS AND METHODS

Twenty-eight patients with lymphoma and a positive CSF cytology were randomized to receive DepoCyt 50 mg once every 2 weeks or free ara-C 50 mg twice a week for 1 month. Patients whose CSF cytology converted to negative and who did not have neurologic progression received an additional 3 months of consolidation therapy and then 4 months of maintenance therapy. All patients received dexamethasone 4 mg orally bid on days 1 through 5 of each 2-week cycle.

RESULTS

The response rate was 71% for DepoCyt and 15% for ara-C on an intent-to-treat basis (P =.006). All of the patients on the DepoCyt arm but only 53% of those on the ara-C arm were able to complete the planned 1-month induction therapy regimen. Time to neurologic progression and survival trend in favor of DepoCyt (median, 78.5 v 42 days and 99.5 v 63 days, respectively; P >.05). DepoCyt treatment was associated with an improved mean change in Karnofsky performance score at the end of induction (P =.041). The major adverse events on both arms were headache and arachnoiditis, which were often caused by the underlying disease.

CONCLUSION

DepoCyt injected once every 2 weeks produced a high response rate and a better quality of life as measured by Karnofsky score relative to that produced by free ara-C injected twice a week.

Dysferlin is a plasma membrane protein and is expressed early in human development

Recently, a single gene, DYSF, has been identified which is mutated in patients with limb-girdle muscular dystrophy type 2B (LGMD2B) and with Miyoshi myopathy (MM). This is of interest because these diseases have been considered as two distinct clinical conditions since different muscle groups are the initial targets. Dysferlin, the protein product of the gene, is a novel molecule without homology to any known mammalian protein. We have now raised a monoclonal antibody to dysferlin and report on the expression of this new protein: immunolabelling with the antibody (designated NCL-hamlet) demonstrated a polypeptide of approximately 230 kDa on western blots of skeletal muscle, with localization to the muscle fibre membrane by microscopy at both the light and electron microscopic level. A specific loss of dysferlin labelling was observed in patients with mutations in the LGMD2B/MM gene. Furthermore, patients with two different frameshifting mutations demonstrated very low levels of immunoreactive protein in a manner reminiscent of the dystrophin expressed in many Duchenne patients. Analysis of human fetal tissue showed that dysferlin was expressed at the earliest stages of development examined, at Carnegie stage 15 or 16 (embryonic age 5-6 weeks). Dysferlin is present, therefore, at a time when the limbs start to show regional differentiation. Lack of dysferlin at this critical time may contribute to the pattern of muscle involvement that develops later, with the onset of a muscular dystrophy primarily affecting proximal or distal muscles.

Identical mutation in patients with limb girdle muscular dystrophy type 2B or Miyoshi myopathy suggests a role for modifier gene(s)

Limb girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM), a distal muscular dystrophy, are both caused by mutations in the recently cloned gene dysferlin, gene symbol DYSF. Two large pedigrees have been described which have both types of patient in the same families. Moreover, in both pedigrees LGMD2B and MM patients are homozygous for haplotypes of the critical region. This suggested that the same mutation in the same gene would lead to both LGMD2B or MM in these families and that additional factors were needed to explain the development of the different clinical phenotypes. In the present paper we show that in one of these families Pro791 of dysferlin is changed to an Arg residue. Both the LGMD2B and MM patients in this kindred are homozygous for this mutation, as are four additional patients from two previously unpublished families. Haplotype analyses suggest a common origin of the mutation in all the patients. On western blots of muscle, LGMD2B and MM patients show a similar abundance in dysferlin staining of 15 and 11%, respectively. Normal tissue sections show that dysferlin localizes to the sarcolemma while tissue sections from MM and LGMD patients show minimal staining which is indistinguishable between the two types. These findings emphasize the role for the dysferlin gene as being responsible for both LGMD2B and MM, but that the distinction between these two clinical phenotypes requires the identification of additional factor(s), such as modifier gene(s).

The cellular immunology of multiple sclerosis

Multiple sclerosis (MS) is a neurological disease that affects the central nervous system (brain and spinal cord) resulting in debilitating motor and sensory dysfunction. Its mean age of onset is 30 years and, with the exception of trauma, MS remains the most frequent cause of neurological disabilities for young adults. The disease is highly variable in its onset and progression. It may not be easily diagnosed, at least in its earliest stages. Significant disability is a hallmark of MS. Indeed, up to 50% of patients require walking aids and 10% are wheelchair-bound at 15 years after an initial diagnosis. Clinical features include deficits in sensory (parasthesias and numbness), motor (difficulties with fine movements and gait), balance, bladder, and sexual functions. Although the etiology for MS is not yet known, it is thought to be related to microbial, genetic, and/or environmental factors. Pathologically, MS is characterized by inflammation. An influx of mononuclear cells occurs through a disrupted blood-brain barrier into an immune-privileged central nervous system. The secretion of a variety of inflammatory cytokines and chemokines from glial cells leads to loss of myelin, disruption of oligodendrocyte integrity, and axonal loss. These events, in large measure, affect progressive neural atrophy. How brain inflammatory activities affect transendothelial migration of leukocytes into the brain and alter the process of myelination are the focal points for MS research activities.

Merosin-positive congenital muscular dystrophy: a large inbred family

Large families with congenital muscular dystrophy are rare. We report a clinical, histopathological, immunocytochemical, electrophysiological, radiological and genetic study of 10 cases affected by "pure" CMD belonging to two generations of a large inbred Palestinian family. The disease showed autosomal recessive inheritance. All patients had generalised muscular weakness and hypotonia at birth without arthrogryposis. They had a relatively benign clinical course with stabilisation of the clinical picture at different ages and at variable degrees of severity. The pattern of muscle weakness and wasting was more marked in the proximal upper limb-girdle and trunk muscles. Lower limb muscles were more mildly involved. Serum CK was normal or moderately increased. All patients had normal intelligence, normal computed tomography (CT) scans of the brain and normal somatosensory evoked potentials (SEP). Electromyography (EMG) and muscle biopsy showed morphological changes compatible with muscular dystrophy. Immunocytochemistry for dystrophin, laminin alpha 2 of merosin, and for alpha, beta, gamma sarcoglycans was normal. Linkage analysis excluded all the known loci for CMD, including laminin alpha 2 on chromosome 6q2, the Fukuyama congenital muscular dystrophy locus on 9q3, the integrin alpha 7 locus on chromosome 12q13 and the recently identified locus on 1p35-36. The family we present is clinically and genetically distinct from the already mapped forms of congenital muscular dystrophy. Genetic studies are in progress to localise the gene responsible for this condition.

Staphylococcus capitis causing aortic valve endocarditis

Coagulase-negative staphylococci have been implicated in certain human infections but are generally considered to be contaminants. Although their clinical significance has been questioned, rare species of coagulase-negative staphylococci such as Staphylococcus capitis and Staphylococcus ludgunensis have recently emerged which cause endocarditis with high morbidity and mortality rates. We report a case of severe aortic valve endocarditis with conduction delays due to S. capitis infection which was treated successfully with antibiotics.

A gene related to Caenorhabditis elegans spermatogenesis factor fer-1 is mutated in limb-girdle muscular dystrophy type 2B

The limb-girdle muscular dystrophies are a genetically heterogeneous group of inherited progressive muscle disorders that affect mainly the proximal musculature, with evidence for at least three autosomal dominant and eight autosomal recessive loci. The latter mostly involve mutations in genes encoding components of the dystrophin-associated complex; another form is caused by mutations in the gene for the muscle-specific protease calpain 3. Using a positional cloning approach, we have identified the gene for a form of limb-girdle muscular dystrophy that we previously mapped to chromosome 2p13 (LGMD2B). This gene shows no homology to any known mammalian gene, but its predicted product is related to the C. elegans spermatogenesis factor fer-1. We have identified two homozygous frameshift mutations in this gene, resulting in muscular dystrophy of either proximal or distal onset in nine families. The proposed name 'dysferlin' combines the role of the gene in producing muscular dystrophy with its C. elegans homology.

Renal involvement in the systemic inflammatory reaction syndrome

Uncontrolled infection quite often leads to systemic inflammatory reaction syndrome (SIRS) and multiorgan dysfunction (MOD) syndrome. Thirty-five consecutive patients (19 males) fulfilling strict diagnostic criteria for SIRS were enrolled in two multicenter prospective double-blind trials involving new therapies for SIRS. The patients were followed prospectively up to day 28 after the enrollment. In the 35 patients with SIRS, males predominated in the age group below 40 (10/12, 83%) compared to the older group (nine males out of 23, 39%). Out of 16 females presenting with SIRS, only two were below the age of 40. This distribution was statistically different than our general MICU population. The serum albumin in these patients was uniformly low, with a mean of 22.5 gm/L. The bulk of SIRS patients (22/35; 63%) went on to develop acute renal failure (ARF). Although statistically not different, skin and peritoneal infections were more common in ARF group while pulmonary infections in non-ARF group. The majority of blood-cultures grew gram-positive organisms. Resolution of SIRS occurred within first 3 days in greater number of non-ARF survivors than ARF survivors (6/9, 66.7% vs. 6/16, 37.5%). Of the 22 ARF patients, 17 showed improvement in their renal function; the five who did not, died before day 28. The overall mortality (about 32%) was similar in both groups. Patients who developed both ARF and ARDS did not survive. In conclusion. SIRS occurs mostly in elderly patients, almost always in patients with low albumin levels. Premenopausal women seem to be protected. Blood cultures isolated a gram-positive organism in the majority of cases. Improvement in serum creatinine suggests good prognosis. The mortality in ARF and non-ARF groups is similar.

Use of the 25 mm flanged esophageal Z stent for malignant dysphagia: a prospective multicenter trial

BACKGROUND

An initial multicenter study using a 21 mm flanged esophageal Z stent demonstrated excellent palliation but an 11% immediate complication rate at placement and a 27% migration rate at 1 month. This North American multicenter trial prospectively studied a 25 mm flanged Z stent to define its palliative ability and whether the increased diameter affected placement or migration problems.

METHODS

Fifty patients who had esophageal Z stents at seven university or regional referral hospitals were prospectively studied. Indications for prosthesis placement, previous therapy, patient demographics, incidence of concomitant tracheoesophageal fistula, and degree of dysphagia were defined, as were procedural and subsequent stent-related problems, survival times, the ability to occlude a tracheoesophageal fistula, and subsequent degree of dysphagia.

RESULTS

Twenty-four patients had infiltrating malignancy (16 exophytic and 10 extrinsic), 9 of whom had concomitant tracheoesophageal fistulas. Ten patients (20%) had misplaced stents requiring retrieval and replacement, 12 patients (24%) had subsequent stent-related problems including exsanguination (2), aspiration (3), tumor overgrowth (3), and postplacement migration (4) (8%). There was statistically significant improvement in prestent versus poststent dysphagia and two thirds of patients had complete occlusion of their tracheoesophageal fistula.

CONCLUSIONS

Redesign of the esophageal Z stent has decreased the migration rate without increasing placement or subsequent erosion problems. Its efficacy appears comparable to the currently marketed Z stent for the palliation of malignant dysphagia and occlusion of tracheoesophageal fistula.

The phenotype of chromosome 2p-linked limb-girdle muscular dystrophy

This study reports on a detailed clinical, electrophysiological, muscle computed tomography (CT) and laboratory investigation carried out on five families with definite linkage to chromosome 2p. Some clinical and laboratory features were common to most of the patients, such as the very high serum creatine kinase (CK) levels (mean 43.70 times the normal). The onset was most frequently in the late teens or early twenties with weakness and wasting of the pelvic girdle muscles. All patients had normal motor milestones and had not complained of any symptoms of muscle disease in early childhood. The clinical course was variable both between and within some families, but was most often slowly progressive. Some variability in the pattern of muscle involvement between the different families has also been observed.

Angiographically documented coronary artery disease in asymptomatic middle aged men suspected of silent ischaemic heart disease

One hundred and fourteen asymptomatic middle aged men, with a positive stress test, underwent coronary angiography at Armed Forces Institute of Cardiology/National Institute of Heart Diseases (AFIC/NIHD), Rawalpindi. Of these, 66 (58%) were found to have significant disease (> 50% luminal narrowing in at least one of the major epicardial arteries) while 48 (42%) had normal coronary arteries. Of the former, 27 (41%) had 1-vessel CAD, 18 (27%) had 2-vessel CAD and 21 (32%) had 3-vessel CAD. There were significantly more hypertensives, hyperlipidaemics and diabetics in CAD group, while other risk factors were the same. The overall risk factor prevalence was low. The major reasons for performing coronary angiography were a positive stress test done as part of routine annual medical checkup and resting ECG changes of enough significance to warrant further investigations. It is concluded that the presence of significant coronary artery disease can be silent in a large number of asymptomatic middle aged men, especially those who have conventional risk factors.

Limb-girdle muscular dystrophy: a follow-up study of 79 patients

The limb-girdle muscular dystrophies (LGMD) are autosomally inherited neuromuscular diseases. Recently six different loci for LGMD have been reported: 5q (LGMD1A), 15q (LGMD2A), 2p (LGMD2B), 13q (LGMD2C), 17q (LGMD2D) and 4p-14-q21.2 (LGMD2E) respectively. We have studied 79 patients affected by LGMD during the period 1976 to 1995. All patients were examined clinically, and various investigations, including genetics were performed. According to their data we divided them as follow: 1) Cases with autosomal recessive inheritance (34.19%) of these two families are linked to chromosome 2p and the others were subdivided according to the age at onset into childhood LGMD and juvenile-adult LGMD; 2) Cases with dominant inheritance (13.92%); 3) Sporadic cases (51.89%). Onset of symptoms occurs from the first to the third decade. The clinical course varies considerably, as does the degree of disability. Our study allowed to identify two different groups of patients who relatively homogeneous with respect to their clinical and laboratory characteristics.

Aup1, a novel gene on mouse chromosome 6 and human chromosome 2p13

We have cloned a novel mouse cDNA, Aup1, encoding a predicted protein of 410 amino acid residues. The 1.5-kb Aup1 transcript is ubiquitously expressed in mouse tissues. An evolutionary relationship to the Caenorhabditis elegans predicted protein F44b9.5 is indicated by the 35% identity and 53% conservation of the amino acid sequences. Nineteen related human ESTs spanning 80% of the protein have also been identified, with a predicted amino acid sequence identity of 86% between the human and the mouse proteins. The gene has been mapped to a conserved linkage group on human chromosome 2p13 and mouse Chromosome 6. Aup1 was eliminated as a candidate gene for two closely linked disorders, human LGMD2B and mouse mnd2.

Genetic and physical mapping at the limb-girdle muscular dystrophy locus (LGMD2B) on chromosome 2p

The limb-girdle muscular dystrophies (LGMD) are a genetically heterogeneous group of disorders, different forms of which have been mapped to at least six distinct genetic loci. We have mapped an autosomal recessive form of LGMD (LGMD2B) to chromosome 2p13. Two other conditions have been shown to map to this region or to the homologous region in mouse: a gene for a form of autosomal recessive distal muscular dystrophy, Miyoshi myopathy, shows linkage to the same markers on chromosome 2p as LGMD2B, and an autosomal recessive mouse mutation mnd2, in which there is rapidly progressive paralysis and muscle atrophy, has been mapped to mouse chromosome 6 to a region showing conserved synteny with human chromosome 2p12-p13. We have assembled a 6-cM YAC contig spanning the LGMD2B locus and have mapped seven genes and 13 anonymous polymorphic microsatellites to it. Using haplotype analysis in the linked families, we have narrowed our region of interest to a 0-cM interval between D2S2113 and D2S2112/D2S145, which does not overlap with the critical region for mnd2 in mouse. Use of these most closely linked markers will help to determine the relationship between LGMD2B and Miyoshi myopathy. YACs selected from our contig will be the starting point for the cloning of the LGMD2B gene and thereby establish the biological basis for this form of muscular dystrophy and its relationship with the other limb-girdle muscular dystrophies.

Main clinical features of the three mapped autosomal recessive limb-girdle muscular dystrophies and estimated proportion of each form in 13 Brazilian families

Autosomal recessive limb-girdle muscular dystrophies (AR LGMD) represent a group of muscle diseases with a wide spectrum of clinical signs, varying from very severe to mild. Four different loci that when mutated cause the AR LGMD phenotype have been mapped or cloned or both: in two of them the linked families seem to have a relatively mild phenotype (LGMD2a and LGMD2b), in the third one the reported linked families show a more severe clinical course (LGMD2c), while mutations in the fourth locus may cause severe or mild phenotypes (LGMD2d). The relative proportion of each of these genetic forms among the LGMD families and whether there are other genes that when mutated cause this phenotype is unknown. The closest available informative markers for each of the mapped AR LGMD genes have been tested in 13 Brazilian families with at least three affected patients. The findings from the present report confirm non-allelic heterogeneity for LGMD and suggest that in our population about 33% of the LGMD families are caused by mutations in the 15q gene, 33% in the 2p gene, 17% by mutations in the adhalin gene, and less than 10% may be by mutations at the 13q locus. They also suggest that there is at least one other gene responsible for this phenotype. In addition, the main clinical features of the different forms are discussed.

T-cell infiltration of primary CNS lymphoma

We stained 13 primary CNS lymphomas (PCNSLs) (six from patients with AIDS, seven from immunocompetent patients) with a panel of antibodies to T cells (pan T cell [CD3], T helper cell [CD4], T suppressor cell [CD8], delta/delta cell [CD4-8-]), B cells (CD20), hematopoietic cells (T200), and NK cell (CD56). We estimated the percentage of tumor cells staining with each antibody. All tumors were B-cell lymphomas. The non-AIDS tumors showed a significant infiltration with CD3+ cells (mean of 10.82% of total cells). The AIDS patients' tumors showed a smaller percentage of CD3+ infiltrating cells (mean, 4.88% of total cells) (p<0.01). CD4+ cells were 9.11% of the total hematopoietic cells in the non-AIDS patients and 3.13% in AIDS patients (p<0.01). AIDS patients showed some CD8+ cells (0.3%), which was significantly higher than in immunocompetent patients (0%) (p<0.05). Very few tumor cells stained with the NK cell and delta/delta cell markers. Both immunocompetent and AIDS patients with PCNSL exhibit significant CD3+ and CD4+ cell infiltration of their tumors; this infiltration is significantly lower in AIDS patients. AIDS patients show a minor CD8+ cell infiltration of their tumors. These results on PCNSL are different from systemic lymphomas, which show a higher CD4 and CD8 cell infiltration, and may offer insights into the more aggressive nature of AIDS-related PCNSL.

Myocardial stunning following respiratory arrest

Myocardial stunning is defined as a prolonged myocardial dysfunction with gradual return of contractile activity after a brief episode of severe ischemia. Usually it is seen in patients with myocardial infarction following treatment with thrombolytic agents, in patients with angina, and in patients recovering from cardiopulmonary bypass surgery. We report an interesting case of myocardial stunning following respiratory arrest.

Nonresective treatment of pineoblastoma: a case report

BACKGROUND

Stereotactic biopsy followed by cytoreductive surgery and/or radiation are the standard treatment for pineoblastoma. We are reporting a patient with a relatively large pineoblastoma, who was treated with a combination of nonresective treatment modalities.

METHOD

The patient is a 20-year-old woman who presented with signs and symptoms of raised intracranial pressure. Magnetic resonance imaging (MRI) showed a large tumor in the pineal region and hydrocephalus. She was emergently treated by placement of a ventriculoperitoneal shunt. Three days later she underwent a stereotactic biopsy, which showed the tumor to be pineoblastoma. She was then further treated with the following treatment modalities: permanent implantation of high activity I125 seeds, external radiation, and chemotherapy.

RESULTS

At 10 months' follow-up, MRI showed complete disappearance of the tumor. At 18 months' follow-up, the patient is asymptomatic, neurologically intact, and her MRI scans show no evidence of intracranial or intraspinal tumor.

CONCLUSIONS

Though the follow-up is relatively short, the results of the nonresective approach in this patient have been excellent.

Confirmation of the 2p locus for the mild autosomal recessive limb-girdle muscular dystrophy gene (LGMD2B) in three families allows refinement of the candidate region

The mild autosomal recessive limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of muscle diseases. The first gene to be mapped and associated with this phenotype was a locus on 15q based on linkage analysis in families from a French geographic isolate. These results have been confirmed in other populations, but it was shown that there is genetic heterogeneity for this form of LGMD. Recently, a second locus has been mapped to chromosome 2p. The confirmation of the mapping of this second locus in LGMD families from different populations is of utmost importance for the positional cloning of this gene (HGMW-approved symbol LGMD2B). In this publication, haplotypes generated from five chromosome 2 markers from all of the known large families linked to chromosome 2p are reported together with the recombinants that show the current most likely location of the LGMD 2B gene.

Blood lead levels and anemia in lead exposed workers

The effects of lead on haematological parameters were studied in 51 occupationally exposed individuals comprising of 27 lead furnace workers, 24 lead pellet handlers and 20 healthy age and service matched controls. Blood lead levels were estimated by atomic absorption spectrometer AAS-180-80 and haematological parameters by Technicon H.1 system. The lead furnace workers had highest blood lead levels (median 71.20 ug/dl, range 21.2-171.10 ug/dl) and low Hb (median 106 g/l, range 73-144 g/l) as compared to healthy subjects (median lead levels 29.80 ug/dl, range 10.20-54.10 ug/dl and Hb median 135 g/l, range 101-153 g/l). The workers handling pellets had moderately increased blood lead levels (median 45.50 ug/dl, range 8.50-130.6 ug/l) and low Hb (median 114 g/l, range 74-158 g/l). The furnace exposed workers had higher blood lead levels and low Hb compared to the lead pellet handlers. TRBC, Hct, MCV, MCH and MCHC did not reveal any significant difference in all groups. It is concluded that chronic lead exposure causes normocytic normochromic anaemia and shows a dose response relationship between lead levels and severity of anemia.

Linkage analyses in British pedigrees suggest a single locus for Darier disease and narrow the location to the interval between D12S105 and D12S129

Darier disease is a dominantly inherited skin disorder in which there appears to be abnormal adhesion between keratinocytes. We and others have shown that the disease in some British pedigrees is closely linked to markers mapping to 12q23-q24.1. In the present study we have defined crossovers that enable us to narrow the location of the disease gene to the interval between the D12S105 and the D12S129 markers. This interval may be expected to be on the order of about 4 cM on the basis of linkage data obtained using the primary CEPH reference families. Our data provide further evidence for locus homogeneity: each of four large British pedigrees, two of which have previously been subjected to preliminary characterization, shows statistically significant evidence for linkage to markers mapping to 12q23-q24.1.