The UTX gene escapes X inactivation in mice and humans

We recently have identified a ubiquitously transcribed mouse Y chromosome gene, Uty , which encodes a tetratricopeptide repeat (TPR) protein. A peptide derived from the UTY protein confers H-Y antigenicity on male cells. Here we report the characterization of a widely transcribed X-linked homologue of Uty , called Utx , which maps to the proximal region of the mouse X chromosome and which detects a human X-linked homologue at Xp11.2. Given that Uty is ubiquitously transcribed, we assayed for Utx expression from the inactive X chromosome (Xi) in mice and found that Utx escapes X chromosome inactivation. Only Smcx and the pseudoautosomal Sts gene on the mouse X chromosome have been reported previously to escape inactivation. The human UTX gene was also found to be expressed from Xi. We discuss the significance of these data for our understanding of dosage compensation of X-Y homologous genes in humans and mice.      

Is fecundability associated with month of birth? An analysis of 19th and early 20th century family reconstitution data from The Netherlands

The relationship between fecundability and month of birth was investigated in a cohort of 1526 women who married between 1802 and 1929, using only women whose first marriage occurred before the age of 35 years. On the basis of their time to pregnancy (TTP, calculated as time between wedding and first birth minus gestational length), women were categorized into two groups: fecunds (TTP up to 12 months or prenuptial conceptions, n = 1348) and subfecunds (TTP >18 months, n = 118). By use of logistic regression, cosinor functions with a period of 1 year or 6 months and variable shift and amplitude were fitted through the monthly odds of subfecunds versus fecunds. The best fitting curve was unimodal, with a zenith in September (P = 0.13 for H0: no differences). Exclusion of childless women (n = 36, minimum follow-up 5 years) from the subfecunds led to a similar curve (P < 0.01), while childless women, as compared with fecunds, showed a birth distribution that was best represented with a bimodal curve with zeniths in January and July (P = 0.06). This study provides evidence for the existence of differences in fecundability by month of birth. The cause of this relationship is unclear, but may lie in a melatonin-dependent circannual variability of the quality of the oocyte.      

Non-cholinergic effects of acetylcholinesterase in the substantia nigra: a possible role for an ATP-sensitive potassium channel

Summary Within the substantia nigra acetylcholinesterase has non-cholinergic actions that can be demonstrated at both behavioural and cellular levels: the aim of this study was, thus, to explore, in the in vitro guinea pig substantia nigra, the ionic mechanisms which mediate these non-classical phenomena. Acetylcholinesterase had a reversible hyperpolarizing action, via an opening of potassium channels, on a selective population of nigral neurons. These neurons could be identified by an ability to generate bursts of action potentials and by a sensitivity to either amphetamine or to a reduction of glucose in the perfusing medium. The acetylcholinesterase-induced hyperpolarization could not be attributed to a contaminant in the exogenous solution, since a highly purified preparation was even more potent. Furthermore, enzymatic action of any kind could be eliminated as boiled acetylcholinesterase was equally efficacious. The effect of acetylcholinesterase was not subject to tachyphylaxis and was resistant to blockade of potassium channels with tetraethylammonium: since both these phenomena are features of the D₂ autoreceptor for dopamine within the substantia nigra, it seems unlikely that acetylcholinesterase is operating on the same target as dendritically released local dopamine. On the other hand, the actions of acetylcholinesterase were enhanced by low glucose and blocked by the sulfonylurea, tolbutamide. These results strongly suggest that acetylcholinesterase can exert a nonenzymatic action and that this action, in the substantia nigra, is mediated by an ATP-sensitive potassium channel.     

A model of corrective gene transfer in X-linked ichthyosis

Single gene recessive genetic skin disorders offer attractive prototypes for the development of therapeutic cutaneous gene delivery. We have utilized X-linked ichthyosis (XLI), characterized by loss of function of the steroid sulfatase arylsulfatase C (STS), to develop a model of corrective gene delivery to human skin in vivo. A new retroviral expression vector was produced and utilized to effect STS gene transfer to primary keratinocytes from XLI patients. Transduction was associated with restoration of full-length STS protein expression as well as steroid sulfatase enzymatic activity in proportion to the number of proviral integrations in XLI cells. Transduced and uncorrected XLI keratinocytes, along with normal controls, were then grafted onto immunodeficient mice to regenerate full thickness human epidermis. Unmodified XLI keratinocytes regenerated a hyperkeratotic epidermis lacking STS expression with defective skin barrier function, effectively recapitulating the human disease in vivo. Transduced XLI keratinocytes from the same patients, however, regenerated epidermis histologically indistinguishable from that formed by keratinocytes from patients with normal skin. Transduced XLI epidermis demonstrated STS expression in vivo by immunostaining as well as a normalization of histologic appearance at 5 weeks post-grafting. In addition, transduced XLI epidermis demonstrated a return of barrier function parameters to normal. These findings demonstrate corrective gene delivery in human XLI patient skin tissue at both molecular and functional levels and provide a model of human cutaneous gene therapy.      

Sexually dimorphic expression of protease nexin-1 and vanin-1 in the developing mouse gonad prior to overt differentiation suggests a role in mammalian sexual development

The mammalian sex-determining pathway is controlled by the presence or absence of SRY expression in the embryonic gonad. Expression of SRY in males is believed to initiate a pathway of gene expression resulting in testis development. In the absence of SRY, ovary development ensues. Several genes have now been placed in this pathway but our understanding of it is far from complete and several functional classes of protein appear to be absent. Sex-determining genes frequently exhibit sexually dimorphic patterns of expression in the developing gonad both before and after overt differentiation of the testis or ovary. In order to identify additional sex-determining or gonadal differentiation genes we have examined gene expression in the developing gonads of the mouse using cDNA microarrays constructed from a normalized urogenital ridge library. We screened for genes exhibiting sexually dimorphic patterns of expression in the gonad at 12.5 and 13.5 days post-coitum, after overt gonad differentiation, by comparing complex cDNA probes derived from male and female gonadal tissue at these stages on micro-arrays. Using in situ hybridization analysis we show here that two genes identified by this screen, protease nexin-1 (Pn-1) and vanin-1 (Vnn1), exhibit male-specific expression prior to overt gonadal differentiation and are detected in the somatic portion of the developing gonad, suggesting a possible direct link to the testis-determining pathway for both genes.     

Acceleration of tetrazolium reduction by bacteria.

Conditions were assessed which would permit more rapid recognition of bacterial growth than has been previously reported using tetrazolium salts. Microtitration trays were used. 2-(p-Iodophenyl)-3(p-nitrophenyl)-5-phenyltetrazolium chloride is rapidly reduced by respiring cells in tissue homogenates but is more toxic than other tetrazoliums when added to growing bacterial cultures. Phenazine methosulfate (PMS), an intermediate electron carrier, potentiates tetrazolium reduction. Growth was readily detected by the addition of these compounds after 3 to 4 h of incubation in Schaedler broth. The final concentration prior to addition to tray wells was 1.0 mg/ml for 2-(p-iodophenyl)-3(p-nitrophenyl)-5-phenyltetrazolium chloride and 0.06 mg/ml for PMS. Addition of 0.5 to 0.8 g of agar per liter of broth enhanced subsequent tetrazolium reduction.     

Transplant ureteral obstruction masquerading as recurrent rejection episodes: management by percutaneous antegrade balloon dilatation

We report a 52-year-old male renal transplant recipient who had three "rejection episodes." The first of these responded to conventional antirejection therapy; however, the next two episodes showed incomplete responses to treatment for rejection. At subsequent presentation with deteriorating renal function, ureteral obstruction was evident and was relieved with percutaneous antegrade balloon dilatation with a return of his plasma creatinine to normal. Obstruction of the ureter was a major component in our patient's course given the lack of response to conventional antirejection therapy and the normalization of renal function with relief of the documented ureteral stenosis. This case illustrates that ureteral obstruction can mimic rejection in the renal transplant recipient. Management of ureteral stenosis in transplant patients with percutaneous antegrade balloon dilatation appears to be an effective procedure and can supplant the need for open surgical procedures.     

Paradigm shift in gastrointestinal surgery − combating sarcopenia with prehabilitation: Multimodal review of clinical and scientific data

A growing body of evidence has demonstrated the prognostic significance of sarcopenia in surgical patients as an independent predictor of postoperative complications and outcomes. These included an increased risk of total complications, major complications, re-admissions, infections, severe infections, 30 d mortality, longer hospital stay and increased hospitalization expenditures. A program to enhance recovery after surgery was meant to address these complications; however, compliance to the program since its introduction has been less than ideal. Over the last decade, the concept of prehabilitation, or “pre-surgery rehabilitation”, has been discussed. The presurgical period represents a window of opportunity to boost and optimize the health of an individual, providing a compensatory “buffer” for the imminent reduction in physiological reserve post-surgery. Initial results have been promising. We review the literature to critically review the utility of prehabilitation, not just in the clinical realm, but also in the scientific realm, with a resource management point-of-view.     

Binding of osteopontin to the osteoclast integrin αvβ3

Occupancy of the chicken osteoclast _v3 integrin stimulates immediate cell signals. Peptides from osteopontin containing Arg-Gly-Asp and peptides from the osteopontin and bone sialoprotein sequences containing Arg-Gly-Asp stimulated immediate reductions in osteoclast cytosolic Ca²⁺. The changes in cytosolic Ca²⁺ required the Arg-Gly-Asp sequence, and were blocked by LM609, a monoclonal antibody to the _v3 integrin. Osteoclast stimulation by the proteins through the integrin did not require immobilization since soluble peptides produced changes in cytosolic Ca²⁺ and inhibited osteoclast binding to bone particles and bone resorption. The decrease in cytosolic Ca²⁺ stimulated by osteopontin and related peptides was due to activation of a plasma membrane Ca²⁺-ATPase. Thus, the data suggest that ligand binding to the osteoclast _v3 integrin results in a reduction in cytosolic Ca²⁺ which participates in regulation of osteoclast function.