bluuebunny/crossref_metadata_2025 huggingface dataset:
WWOX, the common chromosomal fragile site, FRA16D, cancer gene
Authors: Ludes-Meyers J.H. , Bednarek A.K. , Popescu N.C. , Bedford M. , Aldaz C.M.
Published: October 2003

Gross chromosomal rearrangements and aneuploidy are among the most common somatic genomic abnormalities that occur during cancer initiation and progression, in particular in human solid tumor carcinogenesis. The loss of large chromosomal regions as consequence of gross rearrangements (e.g. deletions, monosomies, unbalanced translocations and mitotic recombination) have been traditionally associated with the existence of tumor suppressor genes within the areas affected by the loss of genetic material. The long arm of chromosome 16 was identified as being frequently associated with structural abnormalities in multiple neoplasias, that led us to focus attention on the detailed genetic dissection of this region resulting in the cloning of the putative tumor suppressor gene, WWOX (WW domain containing Oxidoreductase). Interestingly, the WWOX gene resides in the very same region as that of the common chromosomal fragile site 16D (FRA16D). The WWOX gene encodes a protein that contains two WW domains, involved in protein-protein interactions, and a short chain dehydrogenase (SDR) domain, possibly involved in sex-steroid metabolism. We have identified the WWOX WW domain ligand as the PPXY motif confirming the biochemical activity of this domain. WWOX normally resides in the Golgi and we will demonstrate that Golgi localization requires an intact SDR. Inactivation of the WWOX gene during tumorigenesis can occur by homozygous deletions and possibly mutation, however, aberrantly spliced forms of WWOX mRNA have been observed even when one allele is still intact. The aberrantly spliced mRNAs have deletions of the exons that encode the SDR and these WWOX protein isoforms display abnormal intracellular localization to the nucleus possibly functioning as dominant negative inhibitors of full length WWOX. Thus, generation of aberrant transcripts of WWOX may represent a novel mechanism to functionally inactivate WWOX without genomic alteration of the remaining allele. In this article we will review the cloning and identification of WWOX as the target of FRA16D. In addition, we will discuss the possible biochemical functions of WWOX and present evidence that ectopic WWOX expression inhibits tumor growth.
Understanding fragile X syndrome: insights from animal models
Authors: Bakker C.E. , Oostra B.A.
Published: October 2003

The fragile X mental retardation syndrome is caused by large methylated expansions of a CGG repeat in the FMR1 gene leading to the loss of expression of FMRP, an RNA-binding protein. FMRP is proposed to act as a regulator of mRNA transport or translation that plays a role in synaptic maturation and function. To study the physiological function of the FMR1 protein, mouse and Drosophila models have been developed. The loss-of-function mouse model shows slightly enlarged testes, a subtle behavioral phenotype, and discrete anomalies of dendrite spines similar to those observed in brains of patients. Studies in Drosophila indicate that FXMR plays an important role in synaptogenesis and axonal arborization, which may underlie the observed deficits in flight ability and circadian behavior of fxr mutant flies. The relevance of these studies to our understanding of fragile X syndrome is discussed.
Expression of the FMR1 gene
Authors: Tassone F. , Hagerman P.J.
Published: October 2003

Fragile X syndrome is a trinucleotide repeat disorder in which a (CGG)n element located within the 5′ untranslated region of the Fragile X Mental Retardation 1 (FMR1) gene expands to more than 200 copies (full mutation) and becomes hypermethylated. Such expansions are accompanied by the failure to produce FMR1 protein (FMRP), resulting in the fragile X phenotype. For smaller (premutation) expansions (∼55–200 repeats), FMR1 mRNA and FMRP levels had been assumed to be normal; however, our group and others have recently demonstrated that FMR1 mRNA levels are elevated in cells harboring premutation alleles. Moreover, mRNA levels remain elevated in fragile X males with partially methylated full mutation alleles. Finally, some fragile X males with hypermethylated, full mutation alleles continue to produce FMR1 mRNA, despite the expectation that those genes should be silent. These observations all point to a complex mechanism of expression of the FMR1 gene, one that provides a more consistent foundation for the spectrum of clinical involvement. An FMRP deficit is observed in all categories of fragile X individuals, including carriers of the premutation and partially methylated full mutation alleles. These results demonstrate that lowered FMRP levels, in the absence of methylation-coupled silencing of the FMR1 gene, are not caused by reduced transcriptional activity, but rather by a reduced efficiency of translation.
FMR2 function: insight from a mouse knockout model
Authors: Gu Y. , Nelson D.L.
Published: October 2003

The FMR2 gene is dysregulated by the fragile X E triplet repeat expansion in patients with FRAXE mental retardation syndrome. A CCG triplet, located in the 5′ untranslated region of the FRAXE gene undergoes expansion and methylation in these patients, eliminating detectable gene transcription. FRAXE syndrome is distinct from fragile X syndrome, a more common genetic form of mental retardation caused by expansion and methylation of a similar repeat in the FMR1 gene located 600 kb proximal to FRAXE. FRAXE syndrome is rare, and patients’ phenotypes are highly variable, leading to difficulties with predicting specific FMR2 functions based on the human disease. Recently, Lilliputian(Lilli), a Drosophila FMR2 orthologue, was identified; this gene has been linked with several signal transduction pathways, including the transforming growth factor-β (TGF-β) pathway, the Raf/MEK/MAP kinase (MAPK) pathway, and the P13K/PKB pathway. Mutation of Lilli shows defects in germinal band extension, cytoskeletal structure, cell growth, and organ development. The Lilli gene suggests possible functions for FMR2 (and related genes) in humans and mice, but cannot predict specific functions. Modeling Fmr2 mutation in the mouse will be useful to understand specific functions of this gene in vertebrates. This review presents what has been learned thus far from the Fmr2 knockout mouse model and suggests future studies on this model in order to compare it with the human FRAXE mental retardation disorder, Lilli mutants in Drosophila and other mouse models of genes in this family.
Instability of the fragile X syndrome repeat in mice: the effect of age, diet and mutations in genes that affect DNA replication, recombination and repair proficiency
Authors: Fleming K. , Riser D.K. , Kumari D. , Usdin K.
Published: October 2003

Repeat expansion diseases such as fragile X syndrome (FXS) result from increases in the size of a specific tandem repeat array. In addition to large expansions, small changes in repeat number and deletions are frequently seen in FXS pedigrees. No mouse model accurately recapitulates all aspects of this instability, particularly the occurrence of large expansions. This may be due to differences between mice and humans in cis and/or trans-acting factors that affect repeat stability. The identification of such factors may help reveal the expansion mechanism and allow the development of suitable animal models for these disorders. We have examined the effect of age, dietary folate, and mutations in the Werner’s syndrome helicase (Wrn) and Trp53 genes on FXS repeat instability in mice. WRN facilitates replication of the FXS repeat and enhances Okazaki fragment processing, thereby reducing the incidence of processes that have been suggested to lead to expansion. p53 is a protein involved in DNA damage surveillance and repair. We find two types of repeat instability in these mice, small changes in repeat number that are seen at frequencies approaching 100%, and large deletions which occur at a frequency of about 10%. The frequency of these events was independent of WRN, p53, parental age, or folate levels. The large deletions occur at the same frequency in mice homozygous and heterozygous for the repeat suggesting that they are not the result of an interallelic recombination event. In addition, no evidence of large expansions was seen. Our data thus show that the absence of repeat expansions in mice is not due to a more efficient WRN protein or p53-mediated error correction mechanism, and suggest that these proteins, or the pathways in which they are active, may not be involved in expansion in humans either. Moreover, the fact that contractions occur in the absence of expansions suggests that these processes occur by different mechanisms.
Spinocerebellar ataxia type 6 and episodic ataxia type 2: differences and similarities between two allelic disorders
Authors: Mantuano E. , Veneziano L. , Jodice C. , Frontali M.
Published: October 2003

Spinocerebellar ataxia type 6 (SCA6) is one of three allelic disorders caused by mutations of CACNA1A gene, coding for the pore-forming subunit of calcium channel type P/Q. SCA6 is associated with small expansions of a CAG repeat at the 3′ end of the gene, while point mutations are responsible for its two allelic disorders (Episodic Ataxia type 2 and Familial Hemiplegic Migraine). Genetic, clinical, pathological and pathophysiological data of SCA6 patients are reviewed and compared to those of other SCAs with expanded CAG repeats as well as to those of its allelic channelopathies, with particular reference to Episodic Ataxia type 2. Overall SCA6 appears to share features with both types of disorders, and the question as to whether it belongs to polyglutamine disorders or to channelopathies remains unanswered at present.
Spinocerebellar ataxia 7 (SCA7)
Authors: Lebre A.-S. , Brice A.
Published: October 2003

Spinocerebellar ataxia 7 (SCA7) is a progressive autosomal dominant neurodegenerative disorder characterized clinically by cerebellar ataxia associated with progressive macular dystrophy. The disease affects primarily the cerebellum and the retina, but also many other CNS structures as the disease progresses. SCA7 is caused by expansion of an unstable trinucleotide CAG repeat encoding a polyglutamine tract in the corresponding protein, ataxin-7. Normal SCA7 alleles contain 4–35 CAG repeats, whereas pathological alleles contain from 36–306 CAG repeats. SCA7 has a number of features in common with other diseases with polyglutamine expansions: (i) the appearance of clinical symptoms above a threshold number of CAG repeats (>35); (ii) a correlation between the size of the expansion and the rate of progression of the disease: the larger the repeat, the faster the progression; (iii) instability of the repeat sequence (∼12 CAG/transmission) that accounts for the marked anticipation of ∼20 years/generation. The CAG repeat sequence is particularly unstable and de novo mutations can occur during paternal transmissions of intermediate size alleles (28–35 CAG repeats). This can explain the persistence of the disease in spite of the anticipation that should have resulted in its extinction.
Insights into the molecular basis of polyglutamine neurodegeneration from studies of a spinocerebellar ataxia type 7 mouse model
Authors: Grote S.K. , La Spada A.R.
Published: October 2003

Spinocerebellar ataxia type 7 (SCA7) is one member of a growing list of neurodegenerative disorders that are all caused by CAG repeat expansions that produce disease by encoding elongated polyglutamine tracts in a variety of apparently unrelated proteins. In this review, we provide an overview of our efforts to determine the molecular basis of polyglutamine neurotoxicity in SCA7 by modeling this polyglutamine repeat disorder in mice. We discuss how our SCA7 mouse model develops a phenotype that is reminiscent of the retinal and cerebellar disease pathology seen in human patients. All of these findings are considered in the context of numerous other models of polyglutamine disease pathology in mice and other organisms, together with various other in vitro and biochemical studies. We present the competing hypotheses of polyglutamine disease pathogenesis, and explain how our studies of SCA7 brainstem and retinal degeneration using this mouse model have yielded insights into possible mechanisms and pathways of polyglutamine disease pathology. In addition to illustrating how our SCA7 mouse model has allowed us to develop and advance notions of disease pathogenesis, we propose a model of polyglutamine molecular pathology that attempts to integrate the key observations in the field. We close by describing why our SCA7 mouse model should be useful for the next phase of polyglutamine disease research – the development of therapies, and predict that this stage of experimentation will continue to rely heavily on the mouse.
Molecular genetics of spinocerebellar ataxia type 8 (SCA8)
Authors: Mosemiller A.K. , Dalton J.C. , Day J.W. , Ranum L.P.W.
Published: October 2003

We previously reported that a transcribed but untranslated CTG expansion causes a novel form of ataxia, spinocerebellar ataxia type 8 (SCA8) (Koob et al., 1999). SCA8 was the first example of a dominant spinocerebellar ataxia that is not caused by the expansion of a CAG repeat translated into a polyglutamine tract. This slowly progressive form of ataxia is characterized by dramatic repeat instability and a high degree of reduced penetrance. The clinical and genetic features of the disease are discussed below.
Why is SCA12 different from other SCAs?
Authors: Holmes S.E. , O’Hearn E. , Margolis R.L.
Published: October 2003

Spinocerebellar ataxia type 12 (SCA12), now described in European-American and Asian (Indian) pedigrees, is unique among the SCAs from clinical, pathological, and molecular perspectives. Clinically, the distinguishing feature is early and prominent action tremor with variability in other signs. Pathologically, brain MRIs also suggest variability, with promi- nent cortical as well as cerebellar atrophy. Genetically, SCA12 is caused by a CAG repeat expansion that does not encode polyglutamine; we speculate that the mutation may affect expression of the gene PPP2R2B, which encodes a brain-specific regulatory subunit of the protein phosphatase PP2A.
The hereditary spinocerebellar ataxias in Japan
Authors: Sasaki H. , Yabe I. , Tashiro K.
Published: October 2003

In Japan, multiple system atrophy (MSA) accounts for 40% of all spinocerebellar ataxias (SCAs) and hereditary disorders account for 30%. Among the latter, autosomal dominant disorders are common and recessive ataxias are rare. Although the frequency of SCA genotypes differs between geographic regions throughout Japan, SCA6, SCA3/MJD, and DRPLA are the three major disorders, while SCA7, SCA8, SCA10, SCA12, and SCA17 are infrequent or almost undetected. SCA1 predominantly occurs in the northern part of Japan. Overall, 20–40% of dominant SCAs are due to unknown mutations. From this cluster, pure cerebellar ataxias linked with the SCA4, SCA14, and SCA16 locus have been isolated. Among the recessive SCAs, patients with AVED and EAOH have been detected. However, FRDA associated with GAA repeat expansion in the frataxin gene has not been reported so far.
A cerebellar tremor/ataxia syndrome among fragile X premutation carriers
Authors: Hagerman P.J. , Greco C.M. , Hagerman R.J.
Published: October 2003

Fragile X syndrome is a neurodevelopmental disorder that is not known to have any progressive neurological sequelae in adulthood. However, a neurological condition involving intention tremor, ataxia, and cognitive decline has recently been identified among older male carriers of premutation alleles of the FMR1 gene. This condition is clinically distinct from fragile X syndrome and arises through a different molecular mechanism involving the same gene (FMR1). Characteristic findings on magnetic resonance imaging include cerebral and cerebellar volume loss and altered signal intensities of the middle cerebellar peduncles. A striking feature of this fragile X-associated tremor/ataxia syndrome is the presence of ubiquitin-positive neuronal and astroglial intranuclear inclusions. Unlike the CAG repeat expansion diseases, which lead to altered protein products, there is no known protein abnormality among FMR1 premutation carriers. Thus, inclusion formation may reflect a gain-of-function effect of the FMR1 mRNA or the CGG repeat itself. Finally, since this syndrome may represent one of the more common single-gene causes of tremor, ataxia, and dementia among older males, FMR1 DNA testing should be considered when evaluating adult patients with tremor/ataxia.
The epilepsy, the protease inhibitor and the dodecamer: progressive myoclonus epilepsy, cystatin b and a 12-mer repeat expansion
Authors: Lalioti M.D. , Antonarakis S.E. , Scott H.S.
Published: October 2003

Progressive myoclonus epilepsy 1 (EPM1) or Unverricht-Lundborg disease is a human autosomal recessive neurodegenerative disorder caused by mutations in cystatin B (CSTB). The CSTB gene maps to human chromosome 21 and encodes an inhibitor of lysosomal cysteine proteases. Five point mutations have been found, two of which are seen in numerous unrelated patients. However, the main CSTB mutation in EPM1, even among patients of different ethnic origins, is an expansion of a dodecamer repeat (CCCCGCCCCGCG) in the 5′ flanking area of CSTB. Most normal alleles contain either two or three repeats, while rarer normal alleles that are highly unstable contain between 12 and 17 repeats. Mutant expanded alleles have been reported to contain between 30 and 80 copies and are also highly unstable, particularly via parental transmission. There is no apparent correlation between mutant repeat length and disease phenotype. While the repeat expansion is outside the CSTB transcriptional unit, it results in a marked decrease in CSTB expression, at least in certain cell types in vitro. Cstb homozygous knockout mice show some parallels to the phenotype of human EPM1 including myoclonic seizures, development of ataxia and neuropathological changes associated with cell loss via apoptosis. Loss of CSTB function due to mutations is consistent with the observed neurodegenerative pathology and phenotype, but the functional link to the epileptic phenotype of EPM1 remains largely unknown.
Spontaneous chromosome loss and colcemid resistance in lymphocytes from patients with myotonic dystrophy type 1
Authors: Casella M. , Lucarelli M. , Simili M. , Beffy P. , Del Carratore R. , Minichilli F. , Chisari C. , Simi S.
Published: October 2003

Myotonic Dystrophy type 1 (DM1) is one of the many inherited human diseases whose molecular defect is the expansion of a trinucleotide DNA sequence. DM1 shares with fragile X syndrome (FMR1), another “unstable triplet syndrome”, several molecular features not present in the remaining triplet diseases. As FMR1 is also characterised by chromosome instability at the site of the expanded triplet, lymphocytes from DM1 patients and healthy donors were cultured for micronucleus (MN) analysis, in order to verify if DM1 is also prone to chromosome instability. A FISH analysis was also carried out to detect the presence of centromeric sequences in the observed MN. The data indicate that DM1 patients present a percentage of centromere-positive MN significantly higher than controls, suggesting that chromosome loss is the main mechanism underlying the origin of the increased spontaneous instability. To further assess the proneness to instability of cells of DM1 patients, cultures from patients and controls were treated in vitro with growing concentrations of two different mutagens: colcemid, a “pure” aneugen compound whose target is tubulin, and mytomicin C, a strong clastogen. The results show that the patient group is significantly less sensitive to colcemid. These data, together with FISH analysis, suggest the presence, in DM1 patients, of an already damaged tubulin, which becomes no more sensitive to the effect of colcemid and which could be the main defect underlying the aneugenic effects in DM1.
Transgenic mouse models for myotonic dystrophy type 1 (DM1)
Authors: Wansink D.G. , Wieringa B.
Published: October 2003

The study of animal models for myotonic dystrophy type 1 (DM1) has helped us to ‘de- and reconstruct’ our ideas on how the highly variable multisystemic constellation of disease features can be caused by only one type of event, i.e., the expansion of a perfect (CTG)n repeat in the DM1 locus on 19q. Evidence is now accumulating that cell type, cell state and species dependent activities of the DNA replication/repair/recombination machinery contribute to the intergenerational and somatic behavior of the (CTG)n repeat at the DNA level. At the RNA level, a gain-of-function mechanism, with dominant toxic effects of (CUG)n repeat containing transcripts, probably has a central role in DM1 pathology. Parallel study of DM2, a closely related form of myotonic dystrophy, has revealed a similar mechanism, but also made clear that part of the attention should remain focused on a possible role for candidate loss-of-function genes from the DM1 locus itself (like DMWD, DMPK and SIX5) or elsewhere in the genome, to find explanations for clinical aspects that are unique to DM1. This review will focus on new insight regarding structure-function features of candidate genes involved in DM1 pathobiology, and on the mechanisms of expansion and disease pathology that have now partly been disclosed with the help of transgenic animal models.
Transgenic mouse models of spinal and bulbar muscular atrophy (SBMA)
Authors: Katsuno M. , Adachi H. , Inukai A. , Sobue G.
Published: October 2003

Spinal and bulbar muscular atrophy (SBMA) is a late-onset motor neuron disease characterized by proximal muscle atrophy, weakness, contraction fasciculations, and bulbar involvement. Only males develop symptoms, while female carriers usually are asymptomatic. A specific treatment for SBMA has not been established. The molecular basis of SBMA is the expansion of a trinucleotide CAG repeat, which encodes the polyglutamine (polyQ) tract, in the first exon of the androgen receptor (AR) gene. The pathologic hallmark is nuclear inclusions (NIs) containing the mutant and truncated AR with expanded polyQ in the residual motor neurons in the brainstem and spinal cord as well as in some other visceral organs. Several transgenic (Tg) mouse models have been created for studying the pathogenesis of SBMA. The Tg mouse model carrying pure 239 CAGs under human AR promoter and another model carrying truncated AR with expanded CAGs show motor impairment and nuclear NIs in spinal motor neurons. Interestingly, Tg mice carrying full-length human AR with expanded polyQ demonstrate progressive motor impairment and neurogenic pathology as well as sexual difference of phenotypes. These models recapitulate the phenotypic expression observed in SBMA. The ligand-dependent nuclear localization of the mutant AR is found to be involved in the disease mechanism, and hormonal therapy is suggested to be a therapeutic approach applicable to SBMA.
Oculopharyngeal muscular dystrophy: a late-onset polyalanine disease
Authors: Brais B.
Published: October 2003

Oculopharyngeal muscular dystrophy (OPMD) is a muscle disease of late onset associated with progressive ptosis of the eyelids, dysphagia, and unique tubulofilamentous intranuclear inclusions (INIs). OPMD is usually transmitted as an autosomal dominant trait (OMIM 164300). A rarer allelic autosomal recessive form has also been observed (OMIM 257950). Both forms are caused by short (GCG)8–13 expansions in the polyadenylate-binding protein nuclear 1 gene (PABPN1) located on chromosome 14q11.1. The mutations cause the lengthening of an N-terminal polyalanine domain. Both slippage and unequal recombination have been proposed as the mutation mechanisms. The size of the mutation has not yet been conclusively shown to inversely correlate with the severity of the phenotype. Mutated PABPN1 proteins have been shown to be constituents of the INIs. The INIs also contain ubiquitin, proteasome subunits, HSP 40, HSP 70, SKIP, and abundant poly(A)-mRNA. The exact mechanism responsible for polyalanine toxicity in OPMD is unknown. Various intranuclear inclusion dependent and independent mechanisms have been proposed based on the major known function of PABPN1 in polyadenylation of mRNA and its shuttling from the nucleus to the cytoplasm. OPMD is one of the few triplet-repeat diseases for which the function of the mutated gene is known. Because of the increasing number of diseases caused by polyalanine expansions and the pathological overlap with CAG/polyglutamine diseases, what pathological insight is gained by the study of OPMD could lead to a better understanding of a much larger group of developmental and degenerative diseases.
The use of transgenic and knock-in mice to study Huntington’s disease
Authors: Hickey M.A. , Chesselet M.-F.
Published: October 2003

The trinucleotide repeat disorders comprise an ever expanding list of diseases, all of which are caused by an unstable expanded trinucleotide repeat tract. Huntington’s disease (HD) is a member of this family of diseases and more specifically, is a Type II trinucleotide repeat disorder. This means that the mutation in HD is an unstable expanded polyglutamine repeat tract, which is expressed at protein level. There is no cure or beneficial treatment for this fatal neurodegenerative disorder, and patients suffer from progressive motor, cognitive and psychiatric dysfunction. Recent years has seen the development of many genetic models of HD, which allow study of the early phases of disease process, at several different levels of cell function. In addition, these models are being used to investigate the potential of a variety of therapeutic agents for clinical use. Here we review these findings, and their implication for HD pathogenesis.
Mechanisms of neuronal cell death in Huntington’s disease
Authors: Sawa A. , Tomoda T. , Bae B.-I.
Published: October 2003

Huntington’s disease (HD) is a genetically dominant neurodegenerative condition caused by an unique mutation in the disease gene huntingtin. Although the Huntington protein (Htt) is ubiquitously expressed, expansion of the polyglutamine tract in Htt leads to the progressive loss of specific neuronal subpopulations in HD brains. In this article, we will summarize the current understanding on mechanisms of how mutant Htt can elicit cytotoxicity, as well as how the selective sets of neuronal cell death occur in HD brains.
Percutaneous Absorption of Mexoryl SX® in Human Volunteers: Comparison with in vitro Data
Authors: Benech-Kieffer F. , Meuling W.J.A. , Leclerc C. , Roza L. , Leclaire J. , Nohynek G.
Published: October 2003

The potential human health risk of UV filters depends on their toxicity and the human systemic exposure which is a function of the extent of percutaneous absorption of the topically applied substance into the human organism. Using a ‘mass balance’ approach, a study was designed to investigate the systemically absorbed dose of [14C]-Mexoryl SX® in humans after topical application of a typical sunscreen emulsion. In addition, to assess the correlation with in vitro experiments, the percutaneous absorption of this UVA filter through isolated human skin was measured under identical exposure conditions. When applied in vivo for a period of 4 h, 89–94% of the applied radioactivity was recovered from the wash-off samples. In urine samples, the radioactivity slightly exceeded background levels and corresponded maximally to 0.014% of the topically applied dose. No radioactivity was measured in blood or faeces sampled up to 120 h after application. In vitro, 24 h after a 4-hour application, [14C]-Mexoryl SX remained primarily on the skin surface. The mean in vitro absorption over 24 h, adding up the amounts found in the dermis and receptor fluid, was 0.16% of the applied dose. It is concluded from the in vivo pharmacokinetic results that the systemically absorbed dose of [14C]-Mexoryl SX is less than 0.1%. The order of magnitude of this value correlates well with the corresponding in vitro data which overestimate the in vivo results as previously observed with other hydrophilic compounds. This study demonstrates that, under realistic exposure conditions, the human systemic exposure to this UVA filter is negligible and poses no risk to human health.
Testosterone Metabolism in Human Skin Cells in vitro and Its Interaction with Estradiol and Dutasteride
Authors: Münster U. , Hammer S. , Blume-Peytavi U. , Schäfer-Korting M.
Published: October 2003

Since the limited knowledge of cutaneous drug metabolism can impair the development of specifically acting topical dermatics and transdermal application systems, the cell-type-specific androgen metabolism in human skin and its inhibition by drugs were investigated. Cultured human foreskin and scalp skin keratinocytes and fibroblasts as well as occipital scalp dermal papilla cells (DPC) were incubated with testosterone 10–6 and 10–8M alone and in the presence of 17α-estradiol, 17β-estradiol or dutasteride for 24 h. Androgens extracted from culture supernatants were subjected to thin-layer chromatography and quantified by β-counting. In keratinocytes and DPC, dihydrotestosterone (DHT) was only formed to a low extent while androstenedione was the main metabolite. In fibroblasts, DHT formation was pronounced following 10–8M testosterone. Dutasteride 10–8M completely suppressed 5α-dihydro metabolite formation. 17α-Estradiol and 17β-estradiol at nontoxic concentrations decreased 17-ketometabolites. Human skin regulates testosterone action by cell-type-specific activation or deactivation. Effects of 17α-estradiol in androgenetic alopecia are not due to 5α-reductase inhibition. Dutasteride may be useful in acne and androgenetic alopecia.
Hydrating Effects of a Corticoid Oil Formulation and Its Vehicle on Human Skin
Authors: Zhai H. , Ramirez R.G. , Maibach H.I.
Published: October 2003

Factors in the treatment of atopic dermatitis include restoring skin moisture and reducing inflammation. This study evaluated a corticoid oil formulation and its components with respect to their skin hydration potential. Ten healthy Caucasians were enrolled. Five test sites on the left and right forearm of each subject were tested: one site served as a normal skin control (without treatment), whereas four were wetted by spraying distilled water (approximately 0.1 ml) over a 3-cm2 skin surface area, and spraying was repeated every 5 min for a total of three applications. Five minutes after the final application, 0.2 ml of the corticoid oil formulation, moisturizing vehicle, and plain peanut oil were applied to each pre-designated site (3 cm2); one site was kept as a blank control (water saturation only). Thirty minutes later, test sites were gently wiped with paper tissues, and visual scoring, transepidermal water loss (TEWL), and capacitance were recorded and repeated at 2 and 3 h. The corticoid oil formulation, plain peanut oil, and moisturizing vehicle significantly increased skin hydration 30 min after each single application, with no statistically significant difference among the treatments at any point. The corticoid oil formulation and plain peanut oil slightly but not significantly elevated TEWL 30 min after application. The results support intuitive dermatologic judgment of advising patients to apply moisturizing medicaments after bathing.
Detection of Enhanced Monohydroxyeicosatetraenoic Acid and F2-Isoprostane Levels in Human Plasma Samples after Extracorporeal Photoimmunotherapy
Authors: Wiswedel I. , Grundmann J.-U. , Hirsch D. , Gollnick H.
Published: October 2003

To investigate the involvement of reactive oxygen species in extracorporeal photoimmunotherapy (photopheresis), we have introduced two highly sensitive and specific techniques for the detection and quantitative measurement of oxygenated nonenzymatically formed arachidonic acid isomers [mono-hydroxyeicosatetraenoic acids (HETEs) and F2-isoprostanes] by gas chromatography-mass spectrometry/negative ion chemical ionization (GC-MS/NICI) in plasma samples of patients suffering from cutaneous T-cell lymphoma and progressive systemic scleroderma II. The analysis of HETEs involved hydrogenation, solid phase extraction on a C18 cartridge, formation of pentafluorobenzyl bromide and trimethylsilyl ether derivatives. In the case of F2-isoprostanes, the analytical procedure was similar to that of HETEs except that the hydrogenation step was omitted. In the plasma of healthy volunteers picomole amounts of 2-, 5-, 8–12-, 15-HETEs, 8-iso-PGF2α and 9α,11α-PGF2α were quantified by using 12-hydroxy-heptadecatrienoic acid and PGF2α-d4 as internal standards of HETEs and isoprostanes, respectively. Analysis of plasma samples obtained from patients before and after extracorporeal photoimmunotherapy revealed characteristic increases in both, HETE and isoprostane levels. The enhancement of indicators of lipid peroxidation is in correspondence with a moderate loss of α-tocopherol, the most important lipid-soluble antioxidant in human plasma. Thus, our data confirm the involvement of lipid peroxidation in extracorporeal photoimmunotherapy.
HaCaT Cell Proliferation Influenced by Melatonin
Authors: Hipler U.-C. , Fischer T.W. , Elsner P.
Published: October 2003

The hormone melatonin is characterized by numerous pharmacological effects. The influence of melatonin on the growth of the human hair follicle was shown in previous investigations. In the present study, the effects of melatonin were investigated by means of proliferation tests of HaCaT keratinocytes using the [3H]thymidine incorporation, a fluorescence assay with Hoechst dye 33342 and the ATP bioluminescence assay. The aim of the study was to find melatonin concentrations suitable for treatments of the skin and whether there is a cytotoxic effect on HaCaT cells. The different proliferative activity of melatonin depending on its concentration and the time of incubation could be shown in all investigations.
N-Acetyltransferase 2 Acetylation Polymorphism: Prevalence of Slow Acetylators Does Not Differ between Atopic Dermatitis Patients and Healthy Subjects
Authors: Brocvielle H. , Muret P. , Goydadin A.-C. , Boone P. , Broly F. , Kantelip J.-P. , Humbert P.
Published: October 2003

The genetic polymorphism of human N-acetyltransferase 2 (NAT2) divides the human population into groups with rapid, intermediate and slow acetylator status. Slow acetylator status has been considered a predisposing factor for allergic diseases, lupus erythematosus, toxic epidermal necrolysis or Stevens-Johnson syndrome. The aim of this study was to investigate whether Caucasian patients suffering from atopic dermatitis differed from healthy individuals with regard to the genotype and phenotype of NAT2. Twenty unrelated healthy Caucasian volunteers (9 females and 11 males, aged from 22 to 59 years) and twenty unrelated Caucasian patients suffering from atopic dermatitis (9 females and 11 males, aged between 20 and 54 years) participated in this study. For each one, the NAT2 genotype was determined by polymerase chain reaction with DNA extracted from peripheral blood, using specific primers for the wild-type allele (wt) and the 3 most frequent mutated alleles of NAT2 (C481→T, G590→A and G857→A). The NAT2 phenotype was evaluated with dapsone as a test substrate using high-pressure liquid chromatography. Statistical analysis was performed using the χ2 test. Phenotype and genotype were distributed as follows: (1) of the healthy subjects, 60% were rapid acetylators (RA) and 40% were slow acetylators (SA); 10% of the RA and 15% of the SA were homozygous, 50% of the RA and 25% of the SA were heterozygous; (2) of the patients, 55% were RA, 40% were SA and 5% were intermediate acetylators (IA); 10% of the RA and 10% of the SA were homozygous, 45% of the RA and 35% of the SA were heterozygous. No significant statistical difference was found between the two groups for genotypes (p = 0.75) or phenotypes (p = 0.60). The phenotyping and genotyping results of healthy subjects were comparable to those found in previous studies. The absence of a significant statistical difference between healthy subjects and atopic dermatitis patients is in contrast to the results of previous studies. Some authors considered that allergic patients are mostly SAs. This could be explained by the fact that we only considered patients suffering from atopic dermatitis whereas, in other studies, patients suffered from different (one or several associated) allergic diseases. NAT2 polymorphism does not differ between patients suffering from atopic dermatitis and healthy subjects. The importance attributed to the SA status, which was previously considered a predisposing factor for allergic diseases such as atopic dermatitis, should be reviewed.
Role of Isopropyl Myristate, Isopropyl Alcohol and a Combination of Both in Hydrocortisone Permeation across the Human Stratum corneum
Authors: Brinkmann I. , Müller-Goymann C.C.
Published: October 2003

The influence of isopropyl myristate (IPM), isopropyl alcohol (IPA) and a combination of both was studied in view of hydrocortisone (HC) permeation across the human stratum corneum (SC). IPM, IPA and their combination were incorporated into water-containing hydrophilic ointment (WHS), and the resulting effects on HC permeation and on HC accumulation in human SC were investigated as well as the influence of these substances on the microstructure of the SC. Differential scanning calorimetry as well as wide- and small-angle X-ray diffraction show that IPM incorporation into SC results in densely packed bilayer lipids and a loss of order of the corneocyte-bonded lipids. Both effects result in a decreased diffusion coefficient of HC in SC and thus in a decreased permeation rate compared to that of HC from WHS. On the other hand, IPA fluidizes and disrupts the bilayer structure of the intercellular lipids. These effects, concomitant with an increased amount of dissolved HC within the ointment, increase the permeation rate of HC across SC. The combination of both ingredients effects a stronger fluidization and disruption of intercellular lipids than with IPA alone. Therefore, the permeation rate of HC across SC is higher than with IPA alone. Consequently, the IPM and IPA combination acts synergistically on the microstructure of SC.
Epinastine Inhibits Eosinophil Chemotaxis and Adhesion Molecules in Atopic Dermatitis
Authors: Matsukura M. , Yajima A. , Yamazaki F. , Yudate T. , Yamada H. , Tezuka T.
Published: October 2003

Purpose: To investigate the effects of epinastine on eosinophil chemotaxis and changes in eosinophil adhesion molecules induced by epinastine and three other antiallergic agents, using eosinophils of atopic dermatitis (AD) patients. Results: Epinastine reduced eosinophil chemotaxis toward eotaxin when the eosinophils had been prestimulated with interleukin (IL)-5, but given alone it did not alter eosinophil chemotaxis toward IL-5. CD11b expression was inhibited when peripheral blood was prestimulated with IL-5, but eosinophil adhesion molecule expression was not altered. Conclusions: Epinastine suppresses allergic inflammation not only through its strong antihistamine and antimediator effects, but also by inhibiting eosinophilic chemotaxis and the expression of adhesion molecules involved in chemotaxis, especially CD11b.
Complement in Renal Transplantation
Authors: Chowdhury P. , Zhou W. , Sacks S.H.
Published: October 2003

Previous research and therapy in renal transplantation largely focused on the cellular arm of the adaptive immune response. Evidence is emerging that innate immune mechanisms, particularly complement, play a greater role in inflammatory and immune responses against the graft than has been previously recognized. Alternative complement pathway activation appears to mediate renal ischaemia/reperfusion injury, and proximal tubular cells may be both the source and the site of attack of complement components in this setting. Locally produced complement also plays a role in the development of both cellular and antibody-mediated immune responses against the graft. C4d staining has emerged as a useful marker of humoral rejection both in the acute and in the chronic setting and led to renewed interest in the significance of anti-donor antibody formation. A number of therapies are in development which inhibit complement or reduce local synthesis, and may lead to an improved clinical outcome following renal transplantation.
Lean Mass Estimation by Creatinine Kinetics and Dual-Energy X-Ray Absorptiometry in Peritoneal Dialysis
Authors: Negri Armando L. , Barone Roberto , Veron Delma , Fraga Adriana , Arrizurieta Elvira , Zucchini Alfredo , Zanchetta Jose R.
Published: October 2003

Background: Malnutrition is widely prevalent in dialysis. Malnourished patients present depletion of somatic protein stores and a decrease in lean body mass (LBM) that can be measured by different techniques. Aims: (1) To assess the reliability of lean mass measurements obtained by creatinine kinetics (CrK) in a group of stable peritoneal dialysis (PD) patients, using dual-energy x-ray absorptiometry (DEXA) measurements as the reference method; (2) to establish the reproducibility of LBM estimated by CrK in individual patients analyzing repeated measurement in the short term, and (3) to correlate measurements of LBM with laboratory determinations that assess nutritional status. Methods: We performed a cross-sectional evaluation of LBM by DEXA and CrK in 39 PD patients. In 14 patients we performed repeated measurements of LBM by CrK in the short term. Results: No significant difference was found in mean lean mass values estimated by both methods: mean DEXA LBM was 41.7 kg, 36.1 ± 4.5 kg in females and 52.7 ± 6.4 kg in males and mean CrK LBM was 41.08 kg, 37.5 ± 6.1 kg in females and 48.1 ± 8.4 kg in males. A good correlation was found between both techniques (r = 0.71; p < 0.003). The mean difference between the two methods was 0.638 ± 6.95 kg (95% confidence limits: –12.98 and +14.26). A wide scatter of the differences between both methods was seen throughout the range of measurements of LBM. When LBM by CrK was repeatedly (2–3 times) measured in a period of 3–4 months in 14 patients, it had a coefficient of variation (CV) of 15.39% (range 2.89–42.88%), while body weight CV in the same period was 0.69% (range 0–1.9%). Conclusions: CrK is an unsatisfactory method for the assessment of LBM in PD patients.
Predictors of Recurrent Hyperparathyroidism after Total Parathyroidectomy in Chronic Renal Failure
Authors: Stratton Jon , Simcock Meredith , Thompson Hilary , Farrington Ken
Published: October 2003

Background/Aims: Recurrent hyperparathyroidism (HPT) after total parathyroidectomy (TPTX) in chronic renal failure appears more common than might be anticipated. Methods: To study its predictors, we reviewed all 20 cases of TPTX performed at our hospital in a 10-year period. Results: During follow-up (median 46.8 months (range 9.3–120.3)), 15 patients had measurable PTH levels (>10 pg/ml), 7 had levels above the normal range (recurrent HPT), and 3 had PTH levels >300 pg/ml (severe recurrent HPT). Total follow-up post-TPTX was equal in those who developed recurrent HPT and others, but those with recurrent HPT had spent longer on dialysis post-TPTX (61.9 ± 34.9 vs. 21.8 ± 12.0 months; p = 0.001). Patients with recurrent HPT required less vitamin D supplementation during the 10 days post-TPTX (p = 0.025). Log [maximal PTH post-TPTX] correlated with duration of dialysis dependency post-TPTX (r = 0.591, p = 0.006), lowest serum calcium level during the first 30 days post-TPTX (r = 0.449, p = 0.047), and mean serum calcium during the first 30 days post-TPTX (r = 0.546, p = 0.013). Mean log [maximal PTH post-TPTX] was significantly lower in patients with ectopic calcification (p = 0.047). In multiple regression analysis, duration of dialysis post-TPTX and lowest serum calcium level during the first 30 days post-TPTX were the only independent predictors of log [maximal PTH post-TPTX]. Conclusion: Recurrent HPT is common following TPTX and predicted by duration of dialysis dependency post-TPTX, a measure of overall exposure to the uraemic stimulus to parathyroid hyperplasia, and the degree of early hypocalcaemia, possibly reflecting the adequacy of operative parathyroid ablation.
Clinical Effect of Short Daily In-Center Hemodialysis
Authors: Koshikawa Shozo , Akizawa Tadao , Saito Akira , Kurokawa Kiyoshi
Published: October 2003

Background: The safety and efficacy of short daily hemodialysis has been reported in the USA and Europe, but there is no report on its efficacy in Japanese patients undergoing hemodialysis. Methods: Twenty-three outpatients (14 men and 9 women, 55.8 ± 9.6 years old and 11.1 ± 6.6 years on dialysis) undergoing hemodialysis 3 times/week participated in this study. After 4 weeks’ baseline observation under conventional hemodialysis, they were subjected to short daily in-center hemodialysis (DHD, 6 times/week) for 12 weeks and then a 4-week follow-up observation period under conventional hemodialysis. Results: The mean pre-dialysis systolic and diastolic blood pressure significantly decreased in the DHD period. Antihypertensive drugs could be discontinued or the dose was reduced in 6 of 11 patients treated with such drugs. The hematocrit level tended to increase in the DHD period, and recombinant human erythropoietin could be discontinued or reduced in 7 of 14 patients. Localized skin rash caused by the adhesive tape and lidocaine patch at the blood access was observed in only 2 patients, but no other adverse events associated with DHD were noted. Conclusion: These results indicate that DHD is safe and more useful than conventional 3 times/week hemodialysis for Japanese patients undergoing hemodialysis.