Rapid tryptic mapping using enzymatically active mass spectrometer probe tips

A method has been developed for rapid, sensitive, and accurate tryptic mapping of polypeptides using matrix-assisted laser desorption/ionization time-of-flight mass analysis. The technique utilizes mass spectrometer probe tips which have been activated through the covalent immobilization of trypsin. The enzymatically active probe tips were used for the tryptic mapping of chicken egg lysozyme and the results compared with those obtained using either free trypsin or agarose-immobilized trypsin. A significant increase in the overall sensitivity of the process was observed using the active probe tips, as well as the production of more characteristic proteolytic fragments and the elimination of background signals due to the autolysis of the trypsin. Further, probe tip digestions were found to be rapid and convenient.     

Radiation dose in critical organs due to non-coplanar irradiation of the hypophysis

BACKGROUND: In order to estimate the somatic and genetic risk associated with a non-coplanar linac-based radiation technique of the pituitary gland, systematic secondary-dose measurements in a phantom and sample measurements of the dose near critical organs of patients were performed. PATIENTS AND METHODS: For measurements of the dose outside the primary radiation field an acrylic-PVC phantom was used which was irradiated with a single field (4 x 4 cm2). Eight patients with pituitary tumors were treated isocentrically with a combination of sagittal and transverse rotational arcs. To measure the dose in critical organs. LiF thermoluminescence dosimeters (TLD) in chip form were placed onto 1 eyelid, the skin over the thyroid, and the patient's clothes covering the region of breasts and ovaries of female patients and the testicles of male patients. Measurements were performed for all patients during 1 sagittal irradiation and for the majority of patients during 1 transverse irradiation. RESULTS: The phantom measurements demonstrated that the secondary dose measured on the patients surface can be considered as a good approximation for the dose in adjacent organs. The median dose in critical organs for sagittal irradiation was in the range of 25.8 mGy (eyes) to 1.9 mGy (testicles), and for transverse irradiation in the range of 23.3 mGy (eyes) to 1.3 mGy (testicles). The ratio of median organ doses for sagittal and transverse irradiation was 2.1 for the thyroid gland, 1.1 for the eyes, and 1.5 for the other organs. CONCLUSIONS: The dose in critical organs due to non-coplanar irradiation of the pituitary gland is only a small fraction of the dose delivered to the reference point of the planning target volume. The risk of a radiation-induced tumor and a genetic consequence associated with these small doses is generally less than 1% and 0.1%, respectively.     

A randomized prospective trial of the obstetric forceps versus the M-cup vacuum extractor

OBJECTIVE: Our purpose was to determine the efficacy of the obstetric forceps versus the M-cup, a new vacuum extractor cup, and maternal-neonatal complication rates. STUDY DESIGN: Over a 10-month period operative vaginal deliveries were randomized between the obstetric forceps and the M-cup vacuum extractor cup. Maternal demographics, indication for intervention, analgesia, position, station, degree of asynclitism, fetal caput-molding, and time from application to delivery were prospectively recorded. Episiotomy and extensions, lacerations, and the reason for abandonment of the randomized instrument were noted in both groups. Fetal weight, Apgar scores, cord arterial gases, hyperbilirubinemia, phototherapy, and any evidence of fetal trauma were documented at delivery or in the nursery. RESULTS: Six hundred thirty-seven women were randomized, 315 in the forceps group and 322 in the M-cup group. There were no differences in maternal demographic variables. The station, position, degree of asynclitism, or requirement for rotation was not different between the groups. The corrected efficacy rates were forceps 92% and M-cup 94% (p = 0.217). The M-cup deliveries were accomplished more rapidly than forceps deliveries (p < 0.001) and were associated with a lower rate of episiotomy (p < 0.001), third-degree (p < 0.001) and fourth-degree (p = 0.002) lacerations, but blood loss as clinically estimated (p = 0.232) or as measured by hemoglobin levels (p = 0.166) was not significantly different. Forceps deliveries were associated with fewer clinically diagnosed cephalhematomas (p = 0.015) than M-cup deliveries were, but there were no differences in the number of neonates diagnosed with hyperbilirubinemia (p = 0.377) or in the number of infants treated with phototherapy (p = 0.660). CONCLUSIONS: The M-cup vacuum extractor cup appears to be as efficient (and faster) than the obstetric forceps but is associated with significantly more fetal cephalhematomas, whereas maternal injuries are more common with the forceps.