Fibre couplers composed of unequal cores

To obtain the simplest results possible for couplers composed of nearly equal cores, terms of second order have been deliberately neglected in the previous conventional perturbation analysis. Merely by retaining these terms, we obtain the full perturbation results?results which satisfy power conservation exactly and which cannot be improved on within weak coupling. Our derivation shows that the recent `new thoery? of Hardy and Streifer, which necessitates consideration of radiation, is convoluted, unnecessary and contains fundamental errors.     

Age and microdistribution of 210Pb at caribou bone surfaces measured by repeated alpha spectroscopy of 210Po

Caffeine causes a [Ca2+]i increase in the cortex of Paramecium cells, followed by spillover with considerable attenuation, into central cell regions. From [Ca2+]resti approximately 50 to 80 nm, [Ca2+]acti rises within /=2 sec. Chelation of Ca2+o considerably attenuated [Ca2+]i increase. Therefore, caffeine may primarily mobilize cortical Ca2+ pools, superimposed by Ca2+ influx and spillover (particularly in tl cells with empty trichocyst docking sites). In nd cells, caffeine caused trichocyst contents to decondense internally (Ca2+-dependent stretching, normally occurring only after membrane fusion). With 7S cells this usually occurred only to a small extent, but with increasing frequency as [Ca2+]i signals were reduced by [Ca2+]o chelation. In this case, quenched-flow and ultrathin section or freeze-fracture analysis revealed dispersal of membrane components (without fusion) subsequent to internal contents decondensation, opposite to normal membrane fusion when a full [Ca2+]i signal was generated by caffeine stimulation (with Ca2+i and Ca2+o available). We conclude the following. (i) Caffeine can mobilize Ca2+ from cortical stores independent of the presence of Ca2+o. (ii) To yield adequate signals for normal exocytosis, Ca2+ release and Ca2+ influx both have to occur during caffeine stimulation. (iii) Insufficient [Ca2+]i increase entails caffeine-mediated access of Ca2+ to the secretory contents, thus causing their decondensation before membrane fusion can occur. (iv) Trichocyst decondensation in turn gives a signal for an unusual dissociation of docking/fusion components at the cell membrane. These observations imply different threshold [Ca2+]i-values for membrane fusion and contents discharge.     

Fatal pulmonary embolism after total hip arthroplasty: diurnal variations

From 1970 through 1986, a total of 18,104 Charnley low-friction arthroplasties were performed; of these, 122 deaths occurred from pulmonary embolism within 1 year of surgery. Diagnosis was confirmed by postmortem examination in 71% of cases. The exact time of the onset of the complication was recorded in 90 cases. In 74 (82%) cases, the time of collapse occurred during the 7-hour period from 9:00 AM to 4:00 PM, and in 16 (18%) cases, it occurred in the 17-hour period from 4:00 PM to 9:00 AM. The patient's activity at the time of collapse was recorded in 73 cases. Sixty (82%) were mobile, 3 were in the bathroom, and 10 (14%) were in bed. Sixty-six (70.2%) patients died within 1 hour of the onset of symptoms.     

A study of the relationship between syringoceles and Cobb's collar

OBJECT: To assess the association between the congenital narrowing of the bulbar urethra and syringoceles. MATERIALS AND METHODS: Eleven boys were investigated, 10 with a cystogram and 9 with video endoscopy. The video tapes were reviewed with the radiology and the relationship between the syringocele and the narrowing of the bulbar urethra (Cobb's collar) was particularly noted. RESULTS: Seven of the 9 boys examined endoscopically were found to have a Cobb's collar near the proximal extent of the syringocele; the proximal extent of external sphincter appeared to be above and separate from the syringocele in all cases. Six of 10 patients had a syringocele and bulbar urethral narrowing seen at cystogram. CONCLUSIONS: It would appear that syringoceles are often associated with a Cobb's collar, in keeping with the possible origin of both structures from the region of the urogenital membrane. The narrowing in the bulbar urethra may, however, be an incidental finding in many of the cases.     

Growth-regulatory activity of the growth arrest-specific gene, GAS1, in NIH3T3 fibroblasts

The method described detects and confirms presence of pentobarbital residues in dry, extruded feeds at concentrations of 5-20 ppb. Dried feed is ground to a uniform powder and shaken overnight in methanol. A portion of the methanolic extract is evaporated, and the residue is reconstituted in phosphate-buffered saline. The aqueous extract is cleaned with a solid-phase extraction cartridge designed to extract barbiturate residues from biological matrixes. Dimethyl sulfoxide, tetramethylammonium hydroxide, and iodomethane are added to derivatize pentobarbital, 1,3-Dimethyl-pentobarbital is then acidified with dilute hydrochloric acid and extracted with isooctane. The organic layer is transferred and evaporated under a stream of nitrogen. The residue is reconstituted in a small volume of ethyl acetate for analysis by gas chromatography/mass spectrometry. The limit of detection is approximately 0.7 ppb. The method was validated with pentobarbital-fortified feed samples containing high concentrations of meat and bone meal.     

Recombinant vaccinia virus expressing Japanese encephalitis virus protein E

Contrasts are drawn between dental care based on fee-for-service and managed care financial arrangements. The advantages of fee-for-service include (for the profession) slow acceptance of managed care in dentistry compared to medicine; (for society and the patient) more community service, higher technical quality of work, and stimulation of innovations; and (for the individual dentist) the strong dentist-patient bond as well as professionalism.     

Differential effects of fentanyl and morphine on intracellular Ca2+ transients and contraction in rat ventricular myocytes

BACKGROUND: Our objective was to elucidate the direct effects of fentanyl and morphine on cardiac excitation-contraction coupling using individual, field-stimulated rat ventricular myocytes. METHODS: Freshly isolated myocytes were loaded with fura-2 and field stimulated (0.3 Hz) at 28 degrees C. Amplitude and timing of intracellular Ca2+ concentration (at a 340:380 ratio) and myocyte shortening (video edge detection) were monitored simultaneously in individual cells. Real time Ca2+ uptake into isolated sarcoplasmic reticulum vesicles was measured using fura-2 free acid in the extravesicular compartment. RESULTS: The authors studied 120 cells from 30 rat hearts. Fentanyl (30-1,000 nM) caused dose-dependent decreases in peak intracellular Ca2+ concentration and shortening, whereas morphine (3-100 microM) decreased shortening without a concomitant decrease in the Ca2+ transient. Fentanyl prolonged the time to peak and to 50% recovery for shortening and the Ca2+ transient, whereas morphine only prolonged the timing parameters for shortening. Morphine (100 microM), but not fentanyl (1 microM), decreased the amount of Ca2+ released from intracellular stores in response to caffeine in intact cells, and it inhibited the rate of Ca2+ uptake in isolated sarcoplasmic reticulum vesicles. Fentanyl and morphine both caused a downward shift in the dose-response curve to extracellular Ca2+ for shortening, with no concomitant effect on the Ca2+ transient. CONCLUSIONS: Fentanyl and morphine directly depress cardiac excitation-contraction coupling at the cellular level. Fentanyl depresses myocardial contractility by decreasing the availability of intracellular Ca2+ and myofilament Ca2+ sensitivity. In contrast, morphine depresses myocardial contractility primarily by decreasing myofilament Ca2+ sensitivity.