Dissemination of UTC(NIST) over 20 km of commercial optical fiber with active phase stabilization.

We demonstrate the transfer of a cesium frequency standard steered to UTC(NIST) over 20 km of dark telecom optical fiber. Our dissemination scheme uses an active stabilization technique with a phase-locked voltage-controlled oscillator. Out-of-loop characterization of the optical fiber link performance is done with dual-fiber and single-fiber transfer schemes. We observe a fractional frequency instability of 1.5 × 10-12 and 2 × 10-15 at averaging intervals of 1 s and 105 s, respectively, for the link. Both schemes are sufficient to transfer the cesium clock reference without degrading the signal, with nearly an order of magnitude lower fractional frequency instability than the cesium clocks over all time scales. The simplicity of the two-fiber technique may be useful in future long-distance applications where higher stability requirements are not paramount, as it avoids technical complications involved with the single-fiber scheme.

Pegylated interferon plus ribavirin combination therapy for chronic hepatitis C in patients with congenital coagulation disorders.

Chronic hepatitis C (CHC) and end-stage liver disease are becoming an increasingly common cause of mortality in patients with congenital bleeding disorders, especially in the HIV-coinfected group. Combination of pegylated interferon (Peg-IFN) and ribavirin has recently become the treatment of choice for CHC. In this study, we evaluated the safety and efficacy of combination therapy with Peg-IFN plus ribavirin for the treatment of CHC in human immunodeficiency virus (HIV)- and HIV+ patients with congenital bleeding disorders. Between 2000 and 2004, 50 (18-68 years old) patients with CHC (19 HIV+) from two hemophilia centers were included in the study. They were treated with weekly subcutaneous administration of Peg-INF-alpha combined with 800-1,200 mg ribavirin daily, for 24-48 weeks depending on viral genotype. Response was evaluated at weeks 12, 24, 48 (end of treatment response) and 72 had sustained virological response). Overall, 22/50 patients (43.8%) had end of treatment response and 20/50 (40%) sustained virological response. HIV- patients responded similarly to the general population (58.1%), while HIV+ patients had very low response rates (10.5%). The high rate of discontinuation (36.9%) as a result of side effects contributed to the observed low response rate in the HIV+ group. The only factor strongly associated with sustained virological response in the HIV- patients was the reduction of HCV RNA at 12 weeks (p = 0.001). Patients with viral genotypes other than 1 had higher SVR rates, but this was not found to be statistically significant. Peg-INF plus ribavirin is safe for the treatment of CHC monoinfected patients with inherited bleeding disorders, with similar response rates to nonhemophiliacs. On the contrary, in HIV coinfected hemophilic patients under highly active antiretroviral therapy it is associated with severe toxicity and very poor sustained virological response rates. Careful evaluation and several considerations are needed before starting treatment in this population.

Vascular changes of endometrium in early pregnancy.

Spiral arteries, from curetted endometrium, of first-trimester pregnancies, were examined in 342 consecutive cases, comprising 150 primigravida and 192 multigravida . Vascular changes, similar to the "acute atherosis ," described at the end of pregnancy in preeclamptic women, were found. Primigravida had a statistically higher incidence of vascular changes than multigravida . The light microscopic changes were those of intimal proliferation with the presence of foam cells. These intimal cells were mostly myofibroblasts. Mucopolysaccharides also were found in the intima by both light microscopy and ultrastructural studies. The possible importance of the finding of vascular changes in spiral arteries in early pregnancy is discussed.

Decidual vascular changes in early pregnancy as a marker for intrauterine pregnancy.

Endometrial vascular changes similar to atherosclerosis of toxemia of pregnancy were described and graded in 217 consecutive endometrial biopsies of known early intrauterine pregnancy. Severe vascular changes were found in 23.5% of cases. Control material consisting of endometrial biopsies of patients with known cases of tubal ectopic pregnancy and various non-pregnancy menstrual disorders showed minimal or no changes except in one case. A parallel study of Aria-Stella phenomenon in 110 cases of uterine pregnancy showed significant changes in only 3.6% of patients. It is obvious that in these cases of positive Arias-Stella findings, the possibility of an extrauterine pregnancy could not be discarded on histologic grounds alone. The authors suggest the use of the vascular changes of the more severe histologic degree as described in this article as a positive or strongly suspicious marker for intrauterine pregnancy whenever this is needed.

Factors affecting sperm motility. VIII. Velocity and survival of human spermatozoa as related to temperatures above zero.

The effect of temperature on motility and survival of ejaculated human spermatozoa was investigated with the aid of the multiple exposure photography (MEP) method for objective sperm motility determination. Fresh specimens from healthy donors were analyzed while being heated or cooled gradually, or during their storage at various temperatures from 0 to 48 degrees C. Sperm velocity increased steadily from zero to 50.4 nm/sec between freezing point and body temperature. Thereafter, their activity dropped dramatically and total immobilization occurred at 45 degrees C. The induced immobilization was reversible providing exposure to those extreme temperatures was short enough to prevent permanent damage. Sperm survived up to 24-48 h when stored at 23 degrees C, while at body temperature, their survival in vitro was much shorter and rarely extended beyond 12 h. Their longevity was still shorter at higher or lower temperatures, especially when approaching 48 degrees C. With the aid of the combined supravital staining and MEP methods it was found that temperatures of extreme levels induced mainly immobilization rather than a spermicidic effect. The possible mechanism of thermal effect on sperm motility and some of its practical implications are discussed.