Epigenetics in ENS development and Hirschsprung disease

Hirschsprung disease (HSCR, OMIM 142623) is a neurocristopathy caused by a failure of the enteric nervous system (ENS) progenitors derived from neural crest cells (NCCs), to migrate, proliferate, differentiate or survive to and within the gastrointestinal tract, resulting in aganglionosis in the distal colon. The formation of the ENS is a complex process, which is regulated by a large range of molecules and signalling pathways involving both the NCCs and the intestinal environment. This tightly regulated process needs correct regulation of the expression of ENS specific genes. Alterations in the expression of these genes can have dramatic consequences. Several mechanisms that control the expression of genes have been described, such as DNA modification (epigenetic mechanisms), regulation of transcription (transcription factor, enhancers, repressors and silencers), post-transcriptional regulation (3'UTR and miRNAs) and regulation of translation. In this review, we focus on the epigenetic DNA modifications that have been described so far in the context of the ENS development. Moreover we describe the changes that are found in relation to the onset of HSCR.

Human umbilical cord stromal stem cell express CD10 and exert contractile properties

BACKGROUND

It has been demonstrated that human umbilical cord stromal stem cells (UCSSCs) are bio-equivalent to bone marrow mesenchymal stem cells. However, little is known about their tissue origin or in vivo functions, and data on their expansion properties are limited due to early senescence in the culture methods described to date.

METHODS

UC sections and cultured UCSSCs were analyzed with a panel of 12 antibodies. UCSSCs were grown in low-FCS containing medium at 5% or 21% oxygen and were assayed for their clonogenic properties, karyotype stability, expression of specific cellular markers, and multi-lineage potential. UCSSC contractile properties were evaluated by using collagen gel contraction assays under cytokine stimulus.

RESULTS

Immunohistochemistry studies showed that the UCSSCs were derived from the Wharton's jelly and not from the vascular smooth muscle sheath of the blood vessels. UCSSC growth properties were increased in a 5% oxygen atmosphere in comparison to normoxic culture conditions. In both culture conditions, UCSSCs were CD14-, CD34-, and CD45-negative while expressing high levels of CD73, CD90 and CD105 and maintaining their differentiation potentialities. UCSSCs expressed alpha smooth muscle actin and behaved as functional myofibroblasts when cellular contraction was challenged with appropriate stimuli.

CONCLUSIONS

UCSCs are mesenchymal stem cells that reside in the perivascular area of Wharton's jelly and are phenotypically and functionally related to myofibroblasts.

Contribution of RET, NTRK3 and EDN3 to the expression of Hirschsprung disease in a multiplex family

BACKGROUND

Hirschsprung disease (HSCR) is a developmental disorder caused by a defect in the neural crest neuroblast migration process. It is considered to be a paradigm of complex disorders, with many loci contributing to manifestation of the disease. Although HSCR commonly appears as a sporadic trait, approximately 20% of HSCR cases are familial, with complex patterns of inheritance.

METHOD

A multiplex HSCR family with an additive model of inheritance, in which the contribution of three genes (RET, NTRK3, EDN3) leads to the HSCR phenotype is reported.

RESULTS AND DISCUSSION

The findings suggest that both RET and NTRK3 mutations acting together are necessary and sufficient for the appearance of the disease, and that the EDN3 mutation is acting as a phenotype-modifier factor in the context of this family, as two different HSCR phenotypes are seen among the affected members: a short segment form, and a total colonic aganglionosis. The results therefore support the complex additive model of inheritance previously proposed for Hirschsprung disease.

A novel point variant in NTRK3, R645C, suggests a role of this gene in the pathogenesis of Hirschsprung disease

Hirschsprung disease (HSCR) is a developmental disorder characterized by the absence of ganglion cells in the myenteric and submucosal plexuses due to a defect in the migration process of neural crest neuroblasts. Manifestation of the disease has been linked to the dysfunction of two principal signalling pathways involved in the enteric nervous system (ENS) formation: the RET-GDNF and the EDN3-EDNRB receptor systems. However, the NTF3/NTRK3 signalling pathway plays an essential role in the development of the ENS suggesting a potential role for those genes in the pathogenesis of HSCR. We have sought to evaluate the candidature of the NTRK3 gene, which encodes the TrkC receptor, as a susceptibility gene for Hirschsprung disease. Using dHPLC technology we have screened the NTRK3 coding region in 143 Spanish HSCR patients. A total of four previously described polymorphisms and 12 novel sequence variants were detected. Of note, the novel R645C mutation was detected in 2 affected siblings of a HSCR family also carrying a RET splicing mutation. Using bioinformatics tools we observed that the presence of an additional cysteine residue might implicate structural alterations in the mutated protein. We propose haploinsufficiency as the most probable mechanism for the NTRK3 R645C mutation. NTRK3 and RET mutations in this family only appear together in the HSCR patients, suggesting that they per se are necessary but not sufficient to produce the phenotype. In addition, it is quite probable that the contribution of other still unidentified modifier genes, may be responsible for the different phenotypes (length of aganglionosis) in the two affected members.

Polymorphisms in the promoter regions of FAS and FASL genes as candidate genetic factors conferring susceptibility to endometriosis

Although the pathophysiological mechanisms leading to endometriosis remain unknown, several hypothesis have been proposed, including a dysregulation of the normal apoptotic process which takes place in the endometrium. One of the apoptotic pathways playing a crucial role in the programmed cell death within the endometrium is the Fas-FasL system. In this study we have performed a case-control analysis in order to evaluate three polymorphisms located within FAS (-1377G>A and -670A>G) and FASL (-843C>T) genes, as susceptibility factors for endometriosis. We have analysed a series of women with endometriosis compared respectively to a group of women without symptoms of the disease, and to a group of confirmed unaffected women. The genotyping of the three variants was carried out by Fluorescence Resonance Energy Transfer (FRET) technology, and statistical analysis was performed using chi2 test with Yates correction. Our results show that the differences in the distribution of the polymorphic variants were not statistically significant when the group of patients was compared to the other groups. Thus, it seems to indicate that the variants here analysed are not involved in the pathogenesis of the disease in our population. However this does not let us to completely exclude such genes as potential candidates for the disease. A complete genetic analysis of the genes involved in the intricate regulatory system of the apoptosis may lead to the identification of susceptibility factors for the disease and a better understanding of its etiology.

Analysis of the involvement of CCR5-Delta32 and CCR2-V64I variants in the development of endometriosis

Several arguments support the proposal that the cytokine network plays a critical role in the aetiology of endometriosis. Among various chemokines, regulated-on-activation, normal-T-cell-expressed and -secreted (RANTES) and monocyte chemotactic protein 1 (MCP-1) concentrations have been shown to be increased in the peritoneal fluid of women with endometriosis. Some studies have demonstrated that, in the context of endometriosis, these chemokines are involved in apoptosis, angiogenesis and/or chemotaxis. Since the chemokines exert their effects by binding to their receptors, it would be plausible that factors affecting such interactions might play a role in the pathogenesis of endometriosis. Thus we postulated that the genes encoding CCR5 and CCR2, which are the receptors for RANTES and MCP-1 respectively, could be good candidate genes for the disease. We have used real-time PCR and FRET technologies to genotype and evaluate the variants CCR5-Delta32 and CCR2-V64I, as susceptibility factors in a cohort of Spanish women with endometriosis. No differences have been found in the frequencies of the two polymorphisms nor in the haplotype/genotype distribution between cases and controls. These data would suggest the lack of association between these polymorphisms and endometriosis in our population, although they do not permit us to discard completely a possible role of other variants within CCR5 and CCR2 genes in this pathology.

Evaluation of germline sequence variants within the promoter region of RANTES gene in a cohort of women with endometriosis from Spain

The RANTES (regulated upon activation normal T cells expressed and secreted) chemokine, is known to be expressed in endometriotic lesions in a concentration correlating with the severity of endometriosis. Since it has been widely demonstrated that endometriosis has a genetic basis, we postulated that the gene encoding RANTES could be a good candidate gene for the disease. We have used fluorescence resonance energy transfer (FRET) technology to genotype and evaluate the role of the variants -403G-->A and -28C-->G, located within the promoter region of the gene, as susceptibility factors in a cohort of Spanish women with endometriosis. No differences have been found in the allelic frequencies of both variants nor in the haplotype/ genotype distribution between patients and controls. These data are consistent with the lack of association between these polymorphisms and endometriosis in our population. They do not exclude completely a possible role of other variants within RANTES gene in this pathology.

Germline sequence variant S836S in the RET proto-oncogene is associated with low level predisposition to sporadic medullary thyroid carcinoma in the Spanish population

OBJECTIVE

The molecular basis of sporadic medullary thyroid carcinoma (MTC) remains elusive. While germline gain-of-function mutations in the RET proto-oncogene cause hereditary MTC, somatic activating RET mutations and loss of heterozygosity of markers in various chromosomal regions representing deletions of tumour suppressor genes, have been described in a variable number of sporadic MTC. A previous report suggested that the presence of a germline variant at RET codon 836 (S836S) was associated with the development of sporadic MTC and, furthermore, that the presence of S836S was highly correlated with somatic RET M918T mutation in the MTC. Thus, we sought to determine if the S836S variant would be associated with sporadic MTC from a completely different population base, that of Andalucia.

DESIGN

This is a case-control study to determine whether the presence of RET germline S836S is correlated with sporadic MTC in Andalucia.

PATIENTS

Thirty-two patients with sporadic MTC from the Andalucia region of Spain, serviced by our University Hospital, were ascertained throughout the period 1995-99. Sporadic MTC was defined as a lack of personal or family history suggestive of multiple endocrine neoplasia type 2 (MEN 2) and lack of germline RET mutations which define any MEN 2 subtype. A region and race matched cohort of 250 controls was also obtained.

MEASUREMENTS

The frequency of the S836S allele was determined in cases and controls and compared using the standard chi-squared statistic and Fisher's exact test.

RESULTS

The polymorphic allele frequency at codon 836 in the control population (18/500 chromosomes, 3.6%) differed significantly from the MTC case cohort, 9.3% of case chromosomes (six of 64 alleles, Fisher's exact test, two-tailed, P = 0.043).

CONCLUSIONS

Germline RET S836S variant is associated with a two- to three-fold risk of sporadic MTC in the Spanish population, in accordance with a previous study based on German cases. Our observations suggest that this phenomenon might be universal and not limited to Germany.

Helicobacter pylori, hyperammonemia and subclinical portosystemic encephalopathy: effects of eradication

BACKGROUND/AIMS

An involvement of Helicobacter pylori in the development of hepatic encephalopathy in cirrhotic patients has been proposed, but data confirming such an association are lacking. This prospective study aimed to assess whether ammonia levels and indicators of subclinical portosystemic encephalopathy were influenced by H. pylori status in a series of 62 cirrhotic patients. The effects of H. pylori eradication on such parameters were also investigated.

METHODS

Fasting blood ammonia levels, mental state, number connection test, flapping tremor, and EEG tracings were recorded at baseline, and in H. pylori-positive patients (as diagnosed by rapid urease test and 14C-urea breath test) these parameters were reassessed 2 months following eradication therapy.

RESULTS

In this series of non-advanced cirrhotic patients, the prevalence of H. pylori infection was 52%. No significant differences were observed between H. pylori+ and H. pylori- cases with respect to fasting venous blood ammonia concentration (47+/-24 vs. 43+/-22 micromol/l) or to the remaining parameters assessing portosystemic encephalopathy. In addition, H. pylori eradication failed to induce any significant variation in either fasting blood ammonia levels (from 45+/-23 to 48+/-26 micromol/l) or neurologic disturbances.

CONCLUSION

These results indicate that H. pylori infection is not a major contributing factor to either fasting blood ammonia levels or parameters assessing subclinical portosystemic encephalopathy in patients with non-advanced liver cirrhosis.

Turner's syndrome: a behavioral and cytogenetic study

This study focused on the behavioral and cytogenetic aspects of Turner's syndrome. We evaluated the behavioral scores by ESPQ, HSPQ, and TAMAI tests. In the cytogenetic study, six different variables were defined by a chromosome image analysis computer system (Applied Imagine) that assessed changes in band organization and the measurement of mean optical density (MOD) in six G-bands (Xp21, Xq12, Xq21, Xq23, Xq25, Xq27). We studied 33 females with Turner's syndrome and compared them with 30 females individually matched for normal karyotype, short stature, age, and education. Significant differences were found between the two groups.

[Study of diffuse chronic hepatopathy in the outpatient context]

OBJECTIVE

Description of the general characteristics of patients with Diffuse Chronic Hepatopathy (DCH) in an ABS.

DESIGN

Empirical study of a prospective and retrospective type. Site. Primary Care. ABS La Mina. Sant Adrià de Besòs.

PATIENTS AND OTHER PARTICIPANTS

All patients diagnosed as suffering DCH since 1984, in line with histological or clinical--morphological criteria accepted in the literature.

MAIN MEASUREMENTS AND RESULTS

Using a data base of the centre's morbidity and mortality register, 287 reports of patients over 14 years old defined as having DCH were examined. 222 cases met the established criteria. Most of these were males (68%), and to an even higher proportion in the group with alcoholic etiology (84%), which was the most common cause of DCH (64.4%). There was a lower number of complications and deaths attributable to DCH than in published hospital series.

CONCLUSIONS

Among the characteristics of DCH in a natural population using the health services, it is important to note the predominance of compensated forms having a rate of complications and deaths attributable to DCH significantly lower than what was observed in hospital series. This information may be of use in planning activities at the ABS level.

[Quality assurance at a health center: 2 years' experience]

In the Primary Care field there is very little experience of organizing a quality control programme that covers all aspects of care. In our centre, at the beginning of 1989, a Quality Control Commission (QCC) was formed with the aim of establishing and coordinating these activities. We describe our two year experience in this report, with special emphasis on the programme's organizational side and the methodological difficulties we encountered while introducing the programme.

[Ischemic cardiopathy in primary care. A descriptive study]

A descriptive study of ischemic heart disease in a primary care center is reported. From the recording systems 112 patients with IHD (9 of them dead) were identified. The calculated incidence and prevalence rates were 1.9/1000 and 10.9/1000, respectively. There were remarkably high rates of cardiovascular risk factors. The most common forms of presentation were myocardial infarction in males and angina in females. The physicians of the primary care center played a role in the diagnosis in 17% of patients. In addition, the disease was exclusively managed in the primary care center in 29% of patients, most of them over 65 years of age. The role of the primary care physician in the diagnosis and control of this condition is emphasized.

Neural tube defects: a study in Puerto Rico

Recent literature reports an apparent decline in the incidence of neural tube defects throughout the world. A revision of stillbirth certificates and surgical reports of closure procedures for open neural tube defects was done in order to establish the incidence and its trend during a nine year period in Puerto Rico. The current prevalence of the syndrome was estimated using the death certificates in addition to the fore-mentioned surgical reports. Our results indicate that Puerto Rico carries probably the highest incidence of the US territories and that the trend is not declining one.

[Preventing the recurrence of febrile seizures: intermittent prevention with rectal diazepam compared with continuous treatment with sodium valproate]

Sixty nine children suffering from a first febrile seizure without evidence of neurologic disorder or associated risk factors were randomly assigned to one of three groups: no treatment; intermittent rectal diazepam; or continuous oral sodium valproate. All patients were followed for two years. Periodical controls were performed every three months in order to record febrile episodes, recurrent seizures, and treatment side affects. Rate of recurrent febrile seizures was 16% in control group, and 5.5% in diazepam group. Sodium valproate group showed no recurrences in the follow-up period. The low relapsing rate in control group suggests that prophylaxis should not be established even if it is requested by certain parental attitudes.