Citations

The Sonic Hedgehog (Shh) pathway plays important roles in embryogenesis, stem cell maintenance, tissue repair, and tumorigenesis. Haploinsufficiency of Patched-1, a gene that encodes a repressor of the Shh pathway, dysregulates the Shh pathway and increases genomic instability and the development of spontaneous and ionizing radiation (IR)–induced tumors by an unknown mechanism. Here we show that Ptc1+/− mice have a defect in the IR-induced activation of the ATR–Chk1 checkpoint signaling pathway. Likewise, transient expression of Gli1, a downstream target of Shh signaling, disrupts Chk1 activation in human cells by preventing the interaction of Chk1 with Claspin, a Chk1 adaptor protein that is required for Chk1 activation. These results suggest that inappropriate Shh pathway activation promotes tumorigenesis by disabling a key signaling pathway that helps maintain genomic stability and inhibits tumorigenesis.

ABSTRACT Introduction Testosterone replacement therapy has been used in the treatment of sexual dysfunction; however, its use remains controversial, and the effectiveness and long-term health implications are unknown. Aim To evaluate the association between sex hormone serum levels, erectile function, and sexual drive in a population-based sample of men. Methods A stratified random sample of men residing in Olmsted County, Minnesota, completed a questionnaire containing questions from the Brief Male Sexual Function Inventory (BMSFI), and participated in a clinical exam, which included serum hormone measurements. Main Outcome Measures Levels of sexual drive (libido) and erectile function as assessed by the BMSFI and serum testosterone, bioavailable testosterone, and estradiol measurements. Results Out of 414 men, 294 had a regular sexual partner and androgen measurements at the 14th year of follow-up. Total testosterone and erectile function were significantly correlated even after adjustment for age (r = 0.12, P = 0.04). Conversely, total testosterone was not significantly correlated with sex drive (r = 0.08, P = 0.17). Bioavailable testosterone was significantly correlated with both erectile function and sex drive (r = 0.16, P = 0.01 and r = 0.20, P = 0.001, respectively). However, these associations disappeared after age adjustment (r = 0.04 and r = 0.09). Conclusions These cross-sectional results suggest the relationship between sex hormones and sexual function is complex, and that the age-related decline in sexual function may be due to age-related declines in levels of bioavailable testosterone rather than total testosterone levels.

OBJECTIVE. The goal of this study was to evaluate the effect of antibiotic administration before lumbar puncture on cerebrospinal fluid profiles in children with bacterial meningitis. METHODS. We reviewed the medical records of all children (1 month to 18 years of age) with bacterial meningitis who presented to 20 pediatric emergency departments between 2001 and 2004. Bacterial meningitis was defined by positive cerebrospinal fluid culture results for a bacterial pathogen or cerebrospinal fluid pleocytosis with positive blood culture and/or cerebrospinal fluid latex agglutination results. Probable bacterial meningitis was defined as positive cerebrospinal fluid Gram stain results with negative results of bacterial cultures of blood and cerebrospinal fluid. Antibiotic pretreatment was defined as any antibiotic administered within 72 hours before the lumbar puncture. RESULTS. We identified 231 patients with bacterial meningitis and another 14 with probable bacterial meningitis. Of those 245 patients, 85 (35%) had received antibiotic pretreatment. After adjustment for patient age, duration and severity of illness at presentation, and bacterial pathogen, longer duration of antibiotic pretreatment was not significantly associated with cerebrospinal fluid white blood cell count, cerebrospinal fluid absolute neutrophil count. However, antibiotic pretreatment was significantly associated with higher cerebrospinal fluid glucose and lower cerebrospinal fluid protein levels. Although these effects became apparent earlier, patients with ≥12 hours of pretreatment, compared with patients who either were not pretreated or were pretreated for <12 hours, had significantly higher median cerebrospinal fluid glucose levels (48 mg/dL vs 29 mg/dL) and lower median cerebrospinal fluid protein levels (121 vs 178 mg/dL). CONCLUSIONS. In patients with bacterial meningitis, antibiotic pretreatment is associated with higher cerebrospinal fluid glucose levels and lower cerebrospinal fluid protein levels, although pretreatment does not modify cerebrospinal fluid white blood cell count or absolute neutrophil count results.

Abstract Human erythropoiesis is a complex multistep process that involves the differentiation of early erythroid progenitors to mature erythrocytes. Here we show that it is feasible to differentiate and mature human embryonic stem cells (hESCs) into functional oxygen-carrying erythrocytes on a large scale (1010-1011 cells/6-well plate hESCs). We also show for the first time that the oxygen equilibrium curves of the hESC-derived cells are comparable with normal red blood cells and respond to changes in pH and 2,3-diphosphoglyerate. Although these cells mainly expressed fetal and embryonic globins, they also possessed the capacity to express the adult β-globin chain on further maturation in vitro. Polymerase chain reaction and globin chain specific immunofluorescent analysis showed that the cells increased expression of β-globin (from 0% to > 16%) after in vitro culture. Importantly, the cells underwent multiple maturation events, including a progressive decrease in size, increase in glycophorin A expression, and chromatin and nuclear condensation. This process resulted in extrusion of the pycnotic nuclei in up to more than 60% of the cells generating red blood cells with a diameter of approximately 6 to 8 μm. The results show that it is feasible to differentiate and mature hESCs into functional oxygen-carrying erythrocytes on a large scale.