A longevity assurance gene homolog of tomato mediates resistance to Alternaria alternata f. sp. lycopersici toxins and fumonisin B1

The phytopathogenic fungus Alternaria alternata f. sp. lycopersici (AAL) produces toxins that are essential for pathogenicity of the fungus on tomato (Lycopersicon esculentum). AAL toxins and fumonisins of the unrelated fungus Fusarium moniliforme are sphinganine-analog mycotoxins (SAMs), which cause inhibition of sphingolipid biosynthesis in vitro and are toxic for some plant species and mammalian cell lines. Sphingolipids can be determinants in the proliferation or death of cells. We investigated the tomato Alternaria stem canker (Asc) locus, which mediates resistance to SAM-induced apoptosis. Until now, mycotoxin resistance of plants has been associated with detoxification and altered affinity or absence of the toxin targets. Here we show that SAM resistance of tomato is determined by Asc-1, a gene homologous to the yeast longevity assurance gene LAG1 and that susceptibility is associated with a mutant Asc-1. Because both sphingolipid synthesis and LAG1 facilitate endocytosis of glycosylphosphatidylinositol-anchored proteins in yeast, we propose a role for Asc-1 in a salvage mechanism of sphingolipid-depleted plant cells.     

Lenalidomide maintenance after nonmyeloablative allogeneic stem cell transplantation in multiple myeloma is not feasible: results of the HOVON 76 Trial

To improve the outcome of allogeneic stem cell transplantation (allo-SCT) in multiple myeloma as part of first-line treatment, we prospectively investigated the feasibility and efficacy of lenalidomide maintenance. Patients started maintenance 1 to 6 months after nonmyeloablative allo-SCT. Lenalidomide was dosed 10 mg on days 1 to 21 of a 28-day schedule for a total of 24 cycles. Peripheral blood samples were taken to evaluate immune modulating effects. Thirty-five eligible patients were enrolled, and 30 started with lenalidomide. After 2 cycles, 14 patients (47%) had to stop treatment, mainly because of the development of acute graft versus host disease (GVHD). In total, 13 patients (43%) stopped treatment because of development of GVHD, 5 patients (17%) because of other adverse events, and 5 patients (17%) because of progression. Responses improved in 37% of patients, and the estimated 1-year progression-free survival from start of maintenance was 69% (90% confidence interval, 53%-81%). Lenalidomide increased the frequency of human leukocyte antigen-DR(+) T cells and regulatory T cells, without correlation with clinical parameters. In conclusion, lenalidomide maintenance 10 mg daily after nonmyeloablative allo-SCT with unmanipulated graft in multiple myeloma patients is not feasible, mainly because of the induction of acute GVHD. This trial was registered at www.trialregister.nl as #NTR1645.     

Point mutation screening for 16 exons of the dystrophin gene by multiplex single-strand conformation polymorphism analysis

We have developed a rapid and nonradioactive method to screen for point mutations using the Pharmacia Phast System. In an SSCP analysis, we applied the two multiplex exon PCR kits, commonly used for the detection of deletions in Duchenne and Becker muscular dystrophy patients. The different exon bands in the multiplex SSCP pattern could be identified by running well-characterised deletion patients in this system. Two common polymorphisms were easily identifiable and are helpful in the haplotype analysis in families. Screening of 70 patients in which no gross rearrangement was detectable with the multiplex PCR and Southern blot, resulted in the identification of 6 patients with a band shift after -SSCP analysis. Of these 6 band shifts, 5 were the result of a frame shift or termination mutation. The other band shift was found to be a rare polymorphism unlikely to be the cause of the patient's phenotype. Application of this technique enabled us to improve diagnosis in the families involved and will allow us to extend the search for point mutations in the remaining exons of the dystrophin gene. © 1995 Wiley-Liss, Inc.     

Somatic mosaicism of a point mutation in the dystrophin gene in a patient presenting with an asymmetrical muscle weakness and contractures

We describe a patient with somatic mosaicism of a point mutation in the dystrophin gene causing benign muscular dystrophy with an unusual asymmetrical distribution of muscle weakness and contractures. To our knowledge this is the first patient with asymmetrical weakness and contractures in an ambulatory patient with a dystrophinopathy.     

Fatty acid-inducible ANGPTL4 governs lipid metabolic response to exercise

Physical activity increases energy metabolism in exercising muscle. Whether acute exercise elicits metabolic changes in nonexercising muscles remains unclear. We show that one of the few genes that is more highly induced in nonexercising muscle than in exercising human muscle during acute exercise encodes angiopoietin-like 4 (ANGPTL4), an inhibitor of lipoprotein lipase-mediated plasma triglyceride clearance. Using a combination of human, animal, and in vitro data, we show that induction of ANGPTL4 in nonexercising muscle is mediated by elevated plasma free fatty acids via peroxisome proliferator-activated receptor-δ, presumably leading to reduced local uptake of plasma triglyceride-derived fatty acids and their sparing for use by exercising muscle. In contrast, the induction of ANGPTL4 in exercising muscle likely is counteracted via AMP-activated protein kinase (AMPK)-mediated down-regulation, promoting the use of plasma triglycerides as fuel for active muscles. Our data suggest that nonexercising muscle and the local regulation of ANGPTL4 via AMPK and free fatty acids have key roles in governing lipid homeostasis during exercise.Acute exercise greatly increases the cellular demand for ATP, oxygen, glucose, and fatty acids. To meet these demands, acute exercise is associated with marked changes in skeletal muscle activity of key transporters and enzymes involved in glucose and fatty acid transport and oxidation (1). Much of the regulation occurs via allosteric regulation and covalent modification of rate-limiting enzymes. In addition, alterations at the level of mRNA increasingly are believed to represent an important regulatory mechanism in the acute response to exercise (2). Indeed, acute exercise induces mRNA expression of many genes involved in a variety of processes, including energy metabolism, hypertrophy, and signaling (3–6). Not surprisingly, most studies have focused on the events occurring in exercising muscle. In contrast, much less is known about the exercise-induced changes in nonexercising muscle. Studies have shown that resting skeletal muscle is crucial in the removal of lactate from the circulation during high-intensity exercise (7) and also plays a role in adrenaline and noradrenaline production during exercise (8). In addition, similar to exercising muscle, resting muscle exhibits enhanced phosphorylation of mTOR following resistance exercise (9). Overall, however, the impact of exercise on metabolic processes and gene expression in nonexercising muscles remains ill-defined. It can be envisioned that exercise may elicit changes in gene expression in nonexercising muscle via circulating mediators including muscle-derived myokines and metabolites (10). The present study was undertaken to try to elucidate the role of inactive muscle in the metabolic response to acute exercise.     

Asymptomatic and late-onset ornithine transcarbamylase (OTC) deficiency in males of a five-generation family, caused by an A208T mutation

In a large five-generation Polish family, late-onset ornithine transcarbamylase (OTC) deficiency in males segregated with the missense mutation Ala208Thr (A208T), and all heterozygous females were asymptomatic. No other mutations were found in the coding sequences and intron-exon boundaries of the OTC gene. Surprisingly, the mutation originated from the great-grandfather of the index patient who died at age 59 of liver carcinoma. He never had dietary restrictions or hyperammonemic spells throughout life and appears to be the oldest male reported with OTC deficiency. The index patient had a severe OTC deficiency (3% of normal). Eight males died suddenly at ages 4 months to 23 years (average 14 years) after a foudroyant episode triggered by a common infection. The patients remained undiagnosed for 28 years because a metabolic defect was not considered to be the cause of the acute episodes. Recognition of the familial pattern of inheritance was initially unnoticed since the patients were admitted to eight different hospitals. DNA analysis predicted that two 'healthy' boys also had OTC deficiency, which was confirmed by abnormal results of allopurinol challenge tests. Initial suspicion of OTC deficiency in such families is complicated, since symptoms can develop at any age, or even remain absent. This obscures the typical pattern of X-linked inheritance in small families.     

A frame-shift mutation in the type I parathyroid hormone (PTH)/PTH-related peptide receptor causing Blomstrand lethal osteochondrodysplasia.

Blomstrand osteochondrodysplasia (BOCD) is a rare lethal skeletal dysplasia characterized by accelerated endochondral and intramembranous ossification. Comparison of the characteristics of BOCD with type I PTH/PTH-related peptide (PTHrP) receptor-ablated mice reveals striking similarities that are most prominent in the growth plate. In both cases, the growth plate is reduced in size due to a strongly diminished zone of resting cartilage and the near absence of columnar arrangement of proliferating chondrocytes. This overall similarity suggested that an inactivating mutation of the PTH/PTHrP receptor might be the underlying genetic defect causing BOCD. Indeed, inactivating mutations of the PTH/PTHrP receptor have been recently identified in two cases of BOCD. We describe here a novel inactivating mutation in the PTH/PTHrP receptor. Sequence analysis of all coding exons of the type I PTH/ PTHrP receptor gene and complementary DNA of a case with BOCD identified a homozygous point mutation in exon EL2 in which one nucleotide (G at position 1122) was absent. The mutation was inherited from both parents, supporting the autosomal recessive nature of the disease. The missense mutation resulted in a shift in the open reading frame, leading to a truncated protein that completely diverged from the wild-type sequence after amino acid 364. The mutant receptor, therefore, lacked transmembrane domains 5, 6, and 7; the connecting intra- and extracellular loops; and the cytoplasmic tail. Functional analysis of the mutant receptor in COS-7 cells and of dermal fibroblasts obtained from the case proved that the mutation was indeed inactivating. Neither the transiently transfected COS-7 cells nor the dermal fibroblasts responded to a challenge with PTH or PTHrP with a rise in intracellular cAMP levels, in sharp contrast to control cells. Our results provide further evidence that BOCD is caused by inactivating mutations of the type I PTH/PTHrP receptor and underscore the importance of this receptor in mammalian skeletal development.     

Neuropsychologic deficits in children with Langerhans cell histiocytosis.

BACKGROUND: Manifestations of Langerhans cell histiocytosis (LCH) in children range from only a rash, to bony lesions accompanied by pain, to major organ disease. When the central nervous system (CNS) is affected, the LCH patient may exhibit signs and symptoms of hypothalamic and pituitary dysfunction (most often resulting in diabetes insipidus or other endocrinopathies) or more global neurologic and neuropsychologic sequelae. Surprisingly, researchers have only recently begun to examine the neuropsychologic manifestations of the disease, but early findings suggest that they may, in fact, be significant in a small percentage of children with LCH. PROCEDURE: We evaluated two CNS-positive patients with LCH and long-term intermittent treatments, using extensive neuropsychologic assessments, including intellectual functioning, memory, visual-motor functioning, attention and concentration, sensory and motor performance, and gross academic achievement. Objective measures of behavior were obtained through parental report. Neuroradiologic imaging was obtained concurrently with the neuropsychologic evaluations. RESULTS: The neuropsychologic assessments indicated significant deficits in a number of the measured areas of functioning. Global cognitive deficiencies in full-scale IQ were identified, as were deficits in memory, attention/concentration, and perceptual-organizational capabilities. Similarities were noted in the patterns of deficits obtained with both patients, despite differences in the pathophysiology of their disease. Behavioral functioning in both children had suffered, presumably in relation to the neuropsychologic deficits. There were radiologic findings of gross cerebellar white matter damage in one patient, in addition to focal (e.g., hypothalamic) lesions in the other. CONCLUSIONS: LCH has an adverse impact on cognitive functions in some children with evidence of CNS involvement, and further study into the etiology, incidence, and means of remedial intervention is needed.     

Recurrence risk due to germ line mosaicism: Duchenne and Becker muscular dystrophy

The presence of multiple affected offspring from apparently non-carrier parents is caused by germ line mosaicism. Although germ line mosaicism has been reported for many diseases, figures for recurrence risks are known for only a few of them. In X-linked Duchenne and Becker muscular dystrophies (DMD/BMD), the recurrence risk for non-carrier females due to germ line mosaicism has been estimated to be between 14% and 20% (95% confidence interval 3–30) if the risk haplotype is transmitted. In this study, we have analyzed 318 DMD/BMD cases in which the detected mutation was de novo with the aim of obtaining a better estimate of the 'true' number of germ line mosaics and a more precise recurrence risk. This knowledge is essential for genetic counseling. Our data indicate a recurrence risk of 8.6% (4.8–12.2) if the risk haplotype is transmitted, but there is a remarkable difference between proximal (15.6%) (4.1–27.0) and distal (6.4%) (2.1–10.6) deletions. Overall, most mutations originated in the female. Deletions occur more often on the X chromosome of the maternal grandmother, whereas point mutations occur on the X chromosome of the maternal grandfather. In unhaplotyped de novo DMD/BMD families, the risk of recurrence of the mutation is 4.3%.