Continuous-wave broadly tunable Cr2+:ZnSe laser.

We report room-temperature operation of an all-solid-state broadly tunable continuous-wave Cr(2+):ZnSe laser. Output power of 250 mW, an absorbed power slope efficiency of 63%, and continuous tunability from 2138 to 2760 nm are demonstrated.

Room-temperature laser action at 4.34.4 mum in CaGa(2)S(4):Dy(3+).

We report room-temperature mid-IR laser operation in a new low-phonon-frequency nonhygroscopic host crystal, calcium thiogallate (CaGa(2)S(4)) . Laser action at 4.314.38 mum on the Dy(3+)H(11/2)(6)?H(13/2)(6) transition occurred with a maximum slope efficiency of 1.6%.

4.0-4.5-mum lasing of Fe:ZnSe below 180 K, a new mid-infrared laser material.

Lasing of Fe:ZnSe is demonstrated, for the first time to the authors' knowledge, for temperatures ranging from 15 to 180 K. The output wavelength of the Fe:ZnSe laser was observed to tune with temperature from 3.98mum at 15 K to 4.54mum at 180 K. With an Er:YAG laser operating at 2.698mum as the pump source, a maximum energy per pulse of 12muJ at 130 K was produced. Laser slope efficiencies of 3.2% at 19 K and 8.2% at 150 K were determined for an output coupling of 0.6%. A laser emission linewidth of 0.007mum at 3.98mum was measured at 15 K. Absorption and emission spectra and emission lifetimes for Fe:ZnSe are also discussed.

Administration of L-2-oxothiazolidine-4-carboxylate increases glutathione levels in rat brain.

Sterile L-2-oxothiazolidine-4-carboxylate, given as a neutral 100 mmol solution at a dose of 8 mmol/kg subcutaneously, caused an increase in total glutathione concentration in the brain of treated rats. This finding could be important in understanding the role of glutathione in the central nervous system.

Effects of tumor cell viability and inoculum density on growth parameters in the human tumor, soft-agar clonogenic assay.

Four hundred and forty-seven human tumor specimens were accessioned and processed for clonogenic assay, yielding 374 specimens, representing 23 different histiotypes, adequate for culture. Different levels of viable cell inoculum density produced contrasting effects between 255 solid tumors as compared to 72 malignant effusions and 47 bladder washings. All parameters for solid tumor growth were similar except plating efficiency; as inoculum density increased, plating efficiency decreased. For malignant effusions, no significant differences were noted for colony numbers or plating efficiency, but numbers of evaluable cultures increased significantly with increasing inoculum density. Bladder barbotage specimens followed a pattern similar to that of malignant effusions, but the only parameter significantly affected by increasing cell inoculum was colony number which increased proportionally to an increase in number of cells plated. The storage of 109 solid tumors at 4 degrees C, for culture at a later date, resulted in an overall decrease in cell viability (mean, 23.9%) as compared to 161 tumors processed on receipt (mean, 31.1%). This decrease in viability did not adversely affect growth parameters or culture evaluability rates. Based on a lower viable cell inoculum, the percentage of plating efficiencies of stored tumors was significantly higher (geometric mean, 0.127 compared to 0.079 for direct culture), colony numbers were similar for both groups, and culture evaluability rates did not differ greatly (80 and 76%).

Apparent lack of immunogenicity of estrogen-induced testicular Leydig cell tumors in BALB/c mice.

Evaluating four in vivo indicators of immune response, we attempted to demonstrate immunogenic properties in transplantable malignant Leydig cell tumors (LCT) induced in BALB/c mice by chronic estrogen administration. Growing LCT failed to elicit the production either of the lymphokine migration inhibition factor by host splenocytes or of circulating antibodies detectable by indirect immunofluorescence. Delayed type hypersensitivity was evaluated in animals "sensitized" by growing tumor explants. Three to 6 weeks after complete tumor excision, 10(6) viable cells or frozen whole-cell equivalents were injected s.c. in one foot pad, and 2 days later the increase in popliteal node weight on that side was determined. Node hypertrophy of "immunized" animals in numerous experiments using many animals was no greater than that in the naive controls, and no evidence could be obtained to suggest the stimulation of T-suppressor cell activity during tumor growth. Finally, pretransplantation treatment of recipients with 400 rads total-body X-irradiation failed to increase the growth rate of four different tumor lines. Thus, although both estrogen-dependent and -independent transfer lines derived from eight different primary tumors were studied, each by several methodologies, we were unable to obtain evidence to suggest that estrogen-induced LCT in BALB/c mice evoke an immunological response while growing progressively in syngeneic hosts. These findings, plus the absence of recognizable virions in the five tumor lines studied by electron microscopy, argue against the participation of an "expressed" virus in the genesis of LCT. The apparent lack of immunogenicity is also consistent with the indefinite persistence of microscopic foci of viable, though dormant, malignant cells in estrogen-dependent LCT that have undergone complete "clinical" regression following hormone withdrawal.

Single beam schlieren interferometer using a wollaston prism.

A standard single pass schlieren system was converted into a single beam schlieren interferometer by replacing the knife edge with a polarizer-Wollaston prism-analyzer combination. The system is described and an analysis given that relates the fringe shifts on the interferogram to density changes in the test section. The proper location of the density difference is discussed.A complex gas dynamic flow field was investigated with this interferometer, and the results were shown to compare well with theoretical predictions.