0.27-dB/km attenuation achieved by MSP preform process [opticalfibers]

Mechanically shaped preforms (MSP) have been demonstrated to combine economic non-CVD (chemical vapor deposition) processing and low loss, with a published value of 0.63 dB/km and a size of 30 fkm/preform. Improved processing is proposed which results in a minimum loss of 0.27 dB/km at 1550 nm. Preforms capable of yielding 150 fkm have been produced. Reboiling during preform stretching and fiber pulling is identified as the last remaining problem of the process     

Influence of short-term dietary measures on dioxin concentrations in human milk

Breast-feeding may expose infants to high levels of toxic chlorinated dioxins. To diminish intake of these lipophilic compounds by the baby, two diets were tested for their ability to reduce concentrations of dioxins in human milk. The diets were a low-fat/high- carbohydrate/low-dioxin diet. (about 20% of energy intake derived from fat) and a high fat /low-carbohydrate/low-dioxin diet. These diets were tested in 16 and 18 breast-feeding women, respectively. The test diets were followed for 5 consecutive days in the fourth week after delivery. Milk was sampled before and at the end of the dietary regimen, and dioxin concentrations and fatty acid concentrations were determined. Despite significant influences of these diets on the fatty acid profiles, no significant influence on the dioxin concentrations in breast milk could be found. We conclude that short-term dietary measures will not reduce dioxin concentration in human milk.     

Biotin determination by three different methods: specificity and application to urine and plasma ultrafiltrates of patients with and without disorders in biotin metabolism

A microbiological, an avidin-binding and a streptavidin-binding method for biotin determination were compared. All three methods detected biotin equally well but they exhibit different specificities for derivatives of biotin. The microbiological assay has the highest specificity and is the method of choice for biotin determination in biotinidase-deficient patients. The specificity of streptavidin-binding has not been investigated so far. Application of the three methods to urine samples of patients with and without biotin therapy indicated that only 50% of biotin equivalents measured with the avidin method correspond to authentic biotin as previously shown. The other 50% comprise mainly bisnorbiotin and biotin-d-sulfoxide. HPLC-separation of urine samples prior to assay confirmed this finding and revealed a bisnorbiotin oxidation product and an unknown compound as further biotin metabolites. The latter was measurable by all three methods and not detectable in plasma ultrafiltrate. This was the only metabolite which was able to restore deficient 3-methylcrotonyl-CoA carboxylase activity in biotin-deficient fibroblasts. The combination of the three methods together with HPLC-separation proved to be a valuable analytical tool for the identification of the main biotin metabolites in biological fluids.     

RANTES-induced T cell activation correlates with CD3 expression

The chemokine RANTES induces a unique biphasic cytoplasmic Ca2+ signal in T cells. The first phase of this signal, similar to that of other chemokines, is G-protein mediated and chemotaxis associated. The second phase of this signal, unique to RANTES and evident at concentrations greater than 100 nM, is tyrosine kinase linked and results in a spectrum of responses similar to those seen with antigenic stimulation of T cells. We show here that certain jurkat T cells responded to RANTES solely through this latter pathway. A direct correlation between the RANTES-induced second phase response and CD3 expression was demonstrated in these cells. Sorting the Jurkat cells into CD3(high) and CD3(low) populations revealed that only the CD3(high) cells were responsive to RANTES. Furthermore, stimulation of these Jurkat cells with anti-CD3 mAb significantly depresses their subsequent response to RANTES. While a RANTES-specific chemokine receptor is expressed at a low level on these Jurkat cells, the RANTES-induced activation is dependent on the presence of the TCR. Thus, stimulation through TCR may partially account for RANTES' unique pattern of signaling in T cells.     

Stiffness of trabecular bone of the tibial plateau in patients with rheumatoid arthritis of the knee

Stiffness of subchondral proximal tibial trabecular bone is a factor in the stability of prostheses implanted into that bone. The stiffness of trabecular bone in osteoarthritis (OA) has been documented. Trabecular bone in rheumatoid arthritis (RA) is osteopenic in numerous sites and morphologically abnormal in the proximal tibia. Reliable data on proximal tibial bone in RA are lacking, although 1 study failed to identify abnormalities. The purposes of this study were (1) to document the stiffness of the proximal tibial cancellous bone in patients with RA, (2) to determine the effect of angular deformity on bone stiffness in rheumatoid patients, and (3) to compare RA stiffness values with those in published reports for OA. Fifteen tibial plateau were obtained from patients with RA during surgery. Each plateau was horizontally seated in a mold and covered with cement. The plateau was divided into 6 regions, which were used to facilitate comparison between specimens and the existing literature. Indentation tests were conducted with a 4-mm-diameter cylindrical indentor controlled by an MTS machine. The indentor descended at a rate of 2 mm/min to a maximum depth of 1.0 mm; load and displacement data were digitally recorded. Stiffness was calculated from the slope of the linear region of the curve using best-fit linear regression. Where varus deformity was present, stiffness in the medial plateau was higher overall than for the other compartment; whereas in the case of valgus deformity, stiffness of the lateral side was significantly higher (P < .05 for each observation). In comparison to older normal specimens, both the medial compartment of the varus RA specimens (P < .01) and the posterolateral compartment of the valgus RA specimens (P < .01) had significantly lower stiffness. Comparison with OA specimens showed that in varus RA, the posteromedial region had significantly lower stiffness than in varus OA at the same site (P < .01). In valgus RA, the lateral region had significantly lower stiffness than in valgus OA at the same site (P < .01). The mean stiffness ratio of the valgus RA was significantly (P < .01) altered from normal, and for the varus RA, it was significantly (P < .01) different from normal posteriorly. The stiffness ratios for the varus RA were significantly (P < .01) different from those for varus OA; there was no difference between valgus RA and valgus OA. It is concluded that RA affected bone has significantly lower stiffness than normal and osteoarthritic bone. The loaded plateau is stiffer than the unloaded plateau in angular deformity, but is still less stiff than normal bone and osteoarthritic plateaus with corresponding deformities.     

The Dübendorf Study: a population-based investigation on normal values of blood pressure self-measurement

In a retrospective study of 50 consecutive children with posterior fossa tumors treated at Texas Children's Hospital, Houston, Tex., in 1989-1992, we evaluated perioperative factors which might influence the development of postoperative cerebrospinal fluid leaks. Factors analyzed included the presence of preoperative hydrocephalus, the institution of cerebrospinal fluid diversion, and the method of dural closure. No statistically significant impact on subsequent cerebrospinal fluid leakage was demonstrated.