X-chromosome inactivation in development and cancer

X-chromosome inactivation represents an epigenetics paradigm and a powerful model system of facultative heterochromatin formation triggered by a non-coding RNA, Xist, during development. Once established, the inactive state of the Xi is highly stable in somatic cells, thanks to a combination of chromatin associated proteins, DNA methylation and nuclear organization. However, sporadic reactivation of X-linked genes has been reported during ageing and in transformed cells and disappearance of the Barr body is frequently observed in cancer cells. In this review we summarise current knowledge on the epigenetic changes that accompany X inactivation and discuss the extent to which the inactive X chromosome may be epigenetically or genetically perturbed in breast cancer.     

Genetic conflict and evolution of mammalian X-chromosome inactivation

The existence of parentally imprinted gene expression in the somatic tissues of mammals and plants can be explained by a theory of intragenomic genetic conflict, which is a logical extension of classical parent-offspring conflict theory. This theory unites conceptually the phenomena of autosomal imprinting and X-chromosome inactivation. We argue that recent experimental studies of X-chromosome inactivation and andro-genetic development address previously published predictions of the conflict theory, and we discuss possible explanations for the occurrence of random X-inactivation in the somatic tissues of eutherians. © 1995 Wiley-Liss, Inc.     

Self-imposed silence: parental antagonism and the evolution of X-chromosome inactivation

A model is proposed for the evolution of X-chromosome inactivation (XCI) in which natural selection initially favors the silencing of paternally derived alleles of X-linked demand inhibitors. The compensatory upregulation of maternally derived alleles establishes a requirement for monoallelic expression in females. For this reason, XCI is self-reinforcing once established. However, inactivation of a particular X chromosome is not. Random XCI (rXCI) is favored over paternal XCI because rXCI reduces the costs of functional hemizygosity in females. Once present, rXCI favors the evolution of locus-by-locus imprinting of X-linked loci, which creates an evolutionary dynamic in which different chromosomes compete to remain active.     

The long and the short of it: RNA-directed chromatin asymmetry in mammalian X-chromosome inactivation

Mammalian X-chromosome inactivation is controlled by a multilayered silencing pathway involving both short and long non-coding RNAs, which differentially recruit the epigenetic machinery to establish chromatin asymmetries. In response to developmentally regulated small RNAs, dicer, a key effector of RNA interference, locally silences Xist on the active X-chromosome and establishes the heterochromatin conformation along the silent X-chromosome. The 1.6 kb RepA RNA initiates silencing by targeting the PRC2 polycomb complex to the inactive X-chromosome. In addition, the nuclear microenvironment is implicated in the initiation and maintenance of X-chromosome asymmetries. Here we review new findings involving these various RNA species in terms of understanding Xist gene regulation and the establishment of X-chromosome inactivation.     

一个蚕豆病遗传家系G6PD基因突变及X染色体失活偏移检测

对一蚕豆病遗传家系的G6PD基因突变进行分析,检测突变后G6PD酶活变化,并对先证者家系进行X染色体失活（XCI）偏移模式检测,从而预测G6PD突变女性携带者患蚕豆病的风险。取家系成员的外周血样,并提取基因组DNA,用聚合酶链式反应（PCR）和DNA测序法进行序列分析,确定先证者突变位点和突变类型及家庭成员遗传情况,若先证者的母亲和姐姐为G6PD突变携带者,则对先证者母亲和姐姐进行X染色体偏移检测以及酶活检测分析,以评估携带者患蚕豆病的风险,同时对研究对象进行随访。结果患者X染色体上G6PD基因发生点突变c.1376G>T;酶活性检测结果显示该突变使G6PD酶活性下降大约25%,导致蚕豆病发生。该家系的两位女性携带者X染色体失活偏移<80%,未来发生蚕豆病的可能性低。     

儿童不典型黄癣1例报告及文献复习

报告1例由许兰毛癣菌(Trichophyton schoenleinii)引起的儿童不典型黄癣,患儿临床症状轻微,缺乏蜡黄色、碟形黄癣痂和特殊的鼠臭味等典型临床症状.病发真菌直接镜检见大量不规则菌丝,间生膨大,大小不等、形态不规则的孢子,真菌培养为许兰毛癣菌生长,经分子生物学测序鉴定证实.E-test药敏结果显示伊曲康唑、两性霉素B、卡泊芬净及伏立康唑均敏感.经口服伊曲康唑胶囊及外用2％舍他康唑乳膏治疗基本痊愈.     

Hypotriploidy 68,XX: a new case report and review of earlier cases

We report a prematurely born patient with a 68,XX karyotype. She presented with syndactyly of 2nd and 3rd toes, minor facial features, microcephaly, slender hands, bicuspid aortic valve, patent ductus arteriosus and hypotonia. Comparison with other reported cases is given.     

原发肾上腺淋巴瘤1例并文献复习

目的:探讨原发肾上腺淋巴瘤(PAL)的临床特点,提高对该病的认识.方法:对1例原发肾上腺淋巴瘤患者的资料进行分析,并结合国内外相关文献进行总结.结果:原发肾上腺淋巴瘤好发于老年男性,可表现为局部症状如腹痛,腰痛,也可表现为乏力,发热,体重减低等全身症状,50%病人可出现肾上腺功能不全的症状.一些病人是在行影像学检查时因偶然发现肾上腺的肿物,经病理检查而确诊的.该病多累及双侧肾上腺,最常见的病理类型是弥漫大B细胞型.原发肾上腺淋巴瘤的治疗包括手术、化疗、放疗以及它们的不同组合.该病恶性程度高,进展迅速,预后差.结论:原发肾上腺淋巴瘤虽然少见,但在肾上腺肿瘤,尤其是快速增长的肾上腺肿瘤的鉴别诊断中应考虑到它的可能,及时进行病理检查可尽早确诊.     

Gene silencing in transgenic tobacco hybrids: frequency of the event and visualization of somatic inactivation pattern

We have investigated the stability of the expression of different T-DNA-borne genes in hybrid tobacco lines. These lines were constructed to rescue rolC-induced male sterility in kanamycin-resistant P_35s-rolC transgenic tobacco plants by expression of rolC antisense genes. Using five different tester lines, a total of 158 hybrids was obtained. We observed inactivation of transgene expression in 20% of the F₁ progeny and in 35% of the backcrossed F₂ progeny, as indicated by the loss of kanamycin resistance. In 3% of all crosses complete loss of antibiotic resistance was noted, while in most affected hybrid progeny only part of the population became kanamycin sensitive. Single genes could be selectively inactivated on T-DNAs harboring several genes. Gene inactivation was not restricted to one of the two T-DNAs examined. Somatic silencing, visualized by a cell-specific 35SGUSINT marker gene, occurred in a random fashion or exhibited an inherited specific pattern. The type of somatic silencing pattern observed indicated developmental control of the process. Two phenotypic classes could be distinguished with respect to frequency and timing of the inactivation process. Rapid gene inactivation, occurring within a few weeks after germination of hybrid seedlings, was characterized by complete methylation of restriction sites in the promoter of the silenced gene, resetting of gene expression during meiosis, heridity of the developmentally controlled program of gene silencing in subsequent generations, and rapid reactivation of gene expression after genetic separation of the different T-DNAs. In contrast, a slow type of gene inactivation was of a more stochastic nature and was recognized only in hybrids of the backcrossed F₂ generation. In this case the degree of promoter methylation, which could extend beyond the T-DNA borders, was not correlated with the reduction in steady-state poly(A)⁺ mRNA levels, the silenced state was transmitted through meiosis and reactivation lasted several generations. The implications of the observations for our understanding of the gene inactivation process are discussed.     

Lymphoplasmacytic sclerosing pancreato-cholangitis: a case report and review of the literature

Autoimmune pancreatitis is a rare but important cause of pancreatitis that is becoming increasingly recognized in the West. Lymphoplasmacytic sclerosing pancreatitis (LPSP) is a benign form of chronic pancreatitis characterized clinically by infrequent attacks of abdominal pain, jaundice, and weight loss, and pathologically by focal or diffuse chronic or lymphoplasmacytic inflammatory infiltrates centered around pancreatic ducts and ductules, accompanied by obliterative phlebitis, acinar atrophy, and interstitial fibrosis. It has been described alone or as a part of the spectrum of autoimmune gallbladder and biliary tract disease, with clinical, radiological, and pathological overlap reported with primary sclerosing cholangitis. It has been described as "primary sclerosing pancreatitis," "sclerosing cholangitis," "non-alcoholic duct destructive chronic pancreatitis," and "autoimmune pancreatitis." We report a case of LPSP that mimicked pancreatic adenocarcinoma and was subsequently treated with a pylorus-preserving Whipple procedure. This may point towards a primary biliary autoimmune process involving the pancreatic duct, causing a benign form of chronic pancreatitis that may be difficult to characterize pre-operatively to avoid surgery. This case typifies the growing awareness of this relatively recently characterized clinical entity, its similar presentation to pancreatic carcinoma, and the importance for LPSP to be included in the differential diagnosis of pancreaticobiliary disease. Finally, we review the literature.     

Human pentastomiasis in China: case report and literature review

A 13-yr-old boy was admitted because of persistent fever, abdominal pain and diarrhea for 3 mo. Abdomen CT revealed hepatomegaly and multiple nodular low-density pathological changes. At laparotomy considerable yellow and turbid ascites were seen in the abdominal cavity and miliary nodules were noted on the surface of the omentum majus, liver, and small intestine wall. Histological examination revealed parenchymal tubercles containing several worms. Pathological diagnosis was parasitic granuloma. These parasites were identified as Porocephalus taiwana sp.nov. The patient made an uneventful recovery after therapy and was discharged. Moreover, another 17 cases of human pentastomiasis reported from China were reviewed. Human pentastomiasis is an extremely rare disease and this is only the second case of human Porocephalus taiwana sp.nov infection. Pentastomiasis should be considered in differential diagnosis of patients with a history of abdominal symptoms and eating of poorly-cooked snakes.     

Rhinosporidiosis in Egypt: A case report and review of literature

Rhinosporidiosis is an infection caused by Rhinosporidium seeberi that frequently presents as a polypoidal nasal lesions. Here, we report the first indigenous case of tumoral rhinosporidiosis in Egypt. In this case, a 25-year-old male patient from a rural background of Assuit City presented with epistaxis and a nasal polyp. The patient had not traveled abroad. The diagnosis was established on the morphological basis by the identification of 5- to 10-m endospores and 50- to 1000-m sporangia. The clinicopathological and immunologic features were discussed and the literature was reviewed. To the best of our knowledge this is the first case of this disease to be reported in Egypt in the human literature.     

Takotsubo syndrome with pulmonary embolism: a case report and literature review

Background

Takotsubo syndrome (TTS) is an acute cardiac condition with reversible heart failure which is often triggered by psychological and physical stressful events. Although pulmonary embolism (PE) was reported as a trigger for TTS, the concurrence of TTS and PE has been rarely reported, let alone that triggered by PE. Here we describe a case of a postmenopausal female presenting with symptoms similar to myocardial ischemia, which may be caused by PE, and review the available literature that may help clinicians with their practice to similar situations since no published guidelines are available.

Case presentation

An 86-year-old female was referred to the emergency department for unrelieved chest tightness, shortness of breath and back pain. Cardiac biomarkers were mildly elevated and electrocardiogram displayed pathologic Q-waves, ST-segment elevation and inverted T-waves. Unexpectedly, coronary angiography was in absence of obstructed coronary atherosclerosis or acute plaque rupture. Chest computed tomography illustrated multiple pulmonary emboli in bilateral pulmonary arteries. She had suffered from long-term right lower extremity pain and experienced a long railway journey with less activity. Both echocardiogram and cardiac magnetic resonance demonstrated regional hypokinesia of left ventricle. She received anticoagulant and diuretic therapies, three-month follow up after discharge revealed uneventful recovery without any pulmonary emboli or regional motion abnormalities, thus she was retrospectively diagnosed with TTS caused by PE.

Conclusion

TTS and PE are scarcely concurrent and PE can exert as a potential trigger for TTS. TTS is easily misdiagnosed, actively seeking possible risk factors of TTS is in favor of early diagnosis and timely intervention. TTS with PE is reversible, timely and effective treatments ensure the best possible outcome.

     

Malignant struma ovarii: report of a case and review of the literature

Malignant struma ovarii is a very rare disease and therefore there is neither common agreement on treatment regimens nor sufficient follow-up experience. The case of a 38-year-old woman with malignant struma ovarii is described. The patient presented with a clinically silent ovarian neoplasm discovered incidentally during investigations for metrorrhagia. The ovarian mass was resected and the tumor was found to be a teratoma. Within the teratoma a papillary thyroid carcinoma of the follicular variant was found. Subsequently, in order to make follow-up of the patient possible by thyroglobulin measurement and radioiodine whole body scintigraphy, near-total thyroidectomy was performed and the thyroid was found to be normal on histology. Whole body radioiodine scintigraphy with (131)I and ablation of the thyroid remnant by the administration of 80 mCi (131)I was performed. The patient recovered uneventfully and is now well.     

Juvenile breast hypertrophy: report of a familial pattern and review of the literature.

Juvenile hypertrophy of the breast is a relatively rare condition rapidly leading to gigantomastia in peripubertal females. The pathology is limited to the breast, with otherwise normal growth and development. We have reported the first familial pattern seen in this unusual condition. Ablation of the breast is always required. We favor reduction mammaplasty to avoid breast implants, despite the need for additional procedures secondary to recurrent hypertrophy. Our second patient provides support for this approach, demonstrating amelioration in breast growth despite the initial period of rapid regrowth.