Serum concentrations and peritoneal loss of growth hormone and growth-hormone-binding protein activity in older adults undergoing continuous ambulatory peritoneal dialysis: comparison with haemodialysis patients and normal subjects.

Serum concentrations and peritoneal losses of growth hormone (GH) and of growth-hormone-binding protein (GH-BP) activity in 13 patients undergoing continuous ambulatory peritoneal dialysis (CAPD) were compared with those of 13 patients on haemodialysis and 13 normal subjects. The individuals in the three groups were matched by age (40-83 years), gender, and serum glucose concentration. In addition CAPD and haemodialysis patients were matched by haematocrit, serum creatinine and albumin concentrations, and period of time on dialysis (0.5-127 months). GH in the serum and in the peritoneal effluent were measured by radioimmunoassay (RIA) and NB2 bioassay. GH-BP activity was analysed by binding assay and expressed as a percentage of the specific binding of GH. In the haemodialysis patients, serum GH was significantly greater and serum GH-BP activity significantly less than in the CAPD patients and control subjects. Between the two latter groups no significant differences in GH or in GH-BP activity were observed. GH bioactive/immunoactive ratios in the three groups were similar. Both GH and GH-BP were detected in the peritoneal effluent of CAPD patients, in whom an overnight (8-h) peritoneal loss of GH (8.0 +/- 1.4 x 10(-3) micrograms/h/1.73 m2) was strongly correlated with serum GH (r = 0.840). Circulating GH and GH-BP activity were influenced by serum creatinine and haematocrit. In addition a positive relationship was observed between GH-BP activity and body mass index and between GH and time on dialysis. These data reaffirm that older adults undergoing haemodialysis, unlike CAPD patients, exhibit persistent abnormalities in GH-GH-BP axis.(ABSTRACT TRUNCATED AT 250 WORDS)

Cavity-dumped femtosecond Kerr-lens mode-locked Ti:A1(2)O(3)laser.

We report the generation of pulses with energies as high as 100 nJ and durations as short as 50 fs directly from a mode-locked Ti:A1(2)O(3) laser, using the technique of cavity dumping. The simplicity, high energy, short pulse widths, and variable repetition rate of this system make it an attractive tunable source for ultrafast measurements.

Self-focusing-induced saturable loss for laser mode locking.

Self-focusing has recently been used for fast saturable absorber mode locking and femtosecond pulse generation in Ti:Al(2)O(3) lasers. We describe the operation, design, and optimization of self-focusing loss modulators for mode locking. A new formalism is developed that simplifies the treatment of self-focusing in thick nonlinear media by using a simple transform of the complex Gaussian beam parameter. Theoretical predictions are confirmed by experimental measurements.

Examination of factors that may influence disposition of benzo[a]pyrene in vivo: vehicles and asbestos.

Effects of vehicles and of asbestos on disposition of benzo[a]pyrene (B[a]P) were examined in vivo. [3H]B[a]P dissolved in triethylene glycol, ethyl laurate, or tricaprylin was intratracheally administered to male Sprague-Dawley rats. Excretion was most rapid when triethylene glycol was the vehicle, with 70.5% of the recovered dose appearing in bile in 6 h. Lower amounts were excreted into bile when ethyl laurate (58.4%) or tricaprylin (56.2%) were the vehicles, with comparably higher amounts remaining in lungs. When chrysotile asbestos was intratracheally instilled 24 h prior to instillation of [3H]B[a]P dissolved in triethylene glycol, the rate of excretion of radioactivity was slower than without asbestos pretreatment, with only 61.8% of the dose appearing in bile in 6 h.

Serum levels and peritoneal loss of prolactin in CAPD patients.

We studied the serum levels and peritoneal transport of prolactin in 13 CAPD patients and compared with 8 patients on hemodialysis and 10 normal subjects matched by age (30-78 years), sex, body mass index and serum glucose concentrations. CAPD and hemodialysis patients were matched also by hematocrit, serum creatinine, albumin concentrations and duration and dialysis (0-79 months), the prolactin levels in serum and in effluent were measured by RIA and NB2 bioassay. CAPD patients had higher serum prolactin levels than did hemodialysis-treated patients and control subjects. The bioactive/immunoactive ratio of serum prolactin in CAPD patients was 0.7 +/- 0.1 versus 0.9 +/- 0.1 in the control subjects (P less than 0.05) and 0.8 +/- 0.04 in the hemodialysis patients, mean +/- SEM. A significant linear correlation was demonstrated between serum levels and 8 hr peritoneal mass transfer of this hormone. A notable drop of prolactin took place after the first hour of dialysis. Serum prolactin was not influenced by peritoneal protein loss, glucose absorption rate or duration of CAPD. From this study we may conclude that hyperprolactinemia associated with CAPD is not affected by continuous peritoneal loss of prolactin, demonstrating only a slight decrease in bioactivity.

Femtosecond temporal encoding in barium titanate.

We describe two-beam coupling and temporal encoding experiments in barium titanate. Volume gratings are created in the photorefractive material by 50-fs optical pulses. Information in the writing pulses may be encoded as spatially distributed volume gratings in the crystal. Femtosecond temporal waveform reconstruction is demonstrated.