Novel approach reveals genomic landscapes of single-strand DNA breaks with nucleotide resolution in human cells

Single-strand breaks (SSBs) represent the major form of DNA damage, yet techniques to map these lesions genome-wide with nucleotide-level precision are limited. Here, we present a method, termed SSiNGLe, and demonstrate its utility to explore the distribution and dynamic changes in genome-wide SSBs in response to different biological and environmental stimuli. We validate SSiNGLe using two very distinct sequencing techniques and apply it to derive global profiles of SSBs in different biological states. Strikingly, we show that patterns of SSBs in the genome are non-random, specific to different biological states, enriched in regulatory elements, exons, introns, specific types of repeats and exhibit differential preference for the template strand between exons and introns. Furthermore, we show that breaks likely contribute to naturally occurring sequence variants. Finally, we demonstrate strong links between SSB patterns and age. Overall, SSiNGLe provides access to unexplored realms of cellular biology, not obtainable with current approaches.

Hypomagnesemia and smooth muscle contractility: diffuse esophageal spasm in an old female patient

The aim of this paper is to describe and discuss, on the basis of the available literature, the case of an old female patient, admitted to our university hospital because of a severe dysphagia for solid foods, in whom laboratory data showed a marked hypomagnesemia. She reported a long history (20 years) of allergic bronchial asthma treated with theophylline. Esophagography evidenced a disorder of esophagus motility with diffuse multiple spasm, reminiscent of the 'corkscrew esophagus'. A link with the severe hypomagnesemia (Mg 1.1 mEq/l, normal range 1.6-2.1) was suspected, and a therapy with oral pidolate of Mg (1.5 g/twice a day) was started and continued for 4 months. This was associated with a slow progressive normalization of the Mg plasma level and reverted radiographic esophageal findings with disappearance of dysphagia. Mg is an important element for health and disease, and today Mg deficiency in man has become an accepted medical problem which might complicate many diseases. Neuromuscular disorders, as laryngeal spasm, are recognized complications of hypomagnesemia, but until now only 1 case of motor esophageal disorder associated with a low Mg plasma level was briefly reported in the literature, even if dysphagia is generally included in the symptomatological pattern of hypomagnesemia. Our observation of a severe form of esophageal spasm, associated with hypomagnesemia, in an aged female patient underlines the pathophysiological meaning of the plasma Mg level and suggests the need for routine Mg determination in the clinical setting.

A large spontaneous splenorenal shunt in a patient with liver cirrhosis and uncomplicated portal hypertension

The aim of this paper is to describe and discuss, on the basis of a thorough review of the literature, the case of a 70-year-old woman with probable cirrhosis secondary to chronic hepatitis B and C, uncomplicated portal hypertension (without ascites, encephalopathy or bleeding varices), splenomegaly and hypersplenism, and an unusual, spontaneous, large splenorenal shunt and recanalization of the umbilical vein. The tortuous and varicose splenorenal shunt was diagnosed by abdominal ultrasound and CT investigations. A duplex Doppler ultrasonography evaluation was performed to study shunt flow direction and velocity. No gastroesophageal varices were identified on endoscopic examination. The clinical relevance of spontaneous splenorenal shunt, often associated with fundic gastric varices, is discussed.

[Diffuse symptomatic polypoid lipomatosis of the colon with hyperplasia of epiploic appendices: a case report]

Diffuse and symptomatic lipomatosis of the colon, particularly when associated with hyperplasia of the appendices epiploicae, is a rare disease. We report here the case of a lean, 26-year-old woman who had polypoid lipomatosis of the colon with submucosal and subserous expression (involving the mesentery and peritoneum) associated with extreme hyperplasia of the appendices epiploicae. Her disease led to a recurrent subocclusive syndrome which required total colectomy. We discuss the case and review the literature on this subject. The particular characteristics of this case and early onset of disease would suggest that our patient was affected by a congenital lipomatous syndrome linked to mesenchymal dysplasia. Long-term monitoring will enable prompt intervention in the case of reformation of lipomatous tissue.