The impact of mandated in-hospital coverage on primary cesarean delivery rates in a large nonuniversity teaching hospital.

OBJECTIVE: Our purpose was to determine whether attending physician call status affected the primary cesarean delivery rates of the resident or private services after institution of in-hospital coverage. STUDY DESIGN: Data for the study year, during which in-hospital attending coverage was in place, were compared with those of the previous year, during which in-hospital attending coverage of residents was not in place. Birth records were analyzed retrospectively for physician and patient factors. RESULTS: For the year before in-hospital coverage the institutional total cesarean rate was 24.9%, with a primary cesarean section rate of 17.6%. In the first year of coverage the total cesarean delivery was 21.7%, with a decrease in the primary rate to 15.3%. The resident service primary cesarean delivery rate was 10.6% during the study year, which was unchanged from 10.9% the prior year and did not contribute to the overall decrease. Conversely, the private service primary cesarean rate decreased from 18.0% in the prestudy year to 13.4% when the attending physician was on call in the hospital but remained higher at 17.5% when the attending physician was on call not in the hospital. CONCLUSIONS: In-hospital attending physician coverage lowered individual attending physicians' private service primary cesarean rates. Resident service primary cesarean rates were lower than private service and were unaffected by the initiation of in-hospital coverage.

Technetium-99m-labeled monoclonal antibodies for immunoscintigraphy. Simplified preparation and evaluation.

Ascorbic acid incubated with monoclonal antibodies (22 degrees C, 60 min, pH 6.5) at a molar ratio of 3500:1, reduced 2.7 +/- 0.2% of the available disulfides to sulfhydryl groups that strongly bind 99mTc, and provided greater than 95% labeling efficiency for several IgM, IgG and F(ab')2 antibodies. The colloid formation was consistently less than 3% and the stability of the tracer when challenged with DTPA and cysteine was excellent. The immunospecificity of labeled antibodies as determined by immobilized specific antigen assay was 84 +/- 1% for IgM and 82.6 +/- 1.1% for IgG antibodies. For in vivo evaluation in mice bearing experimental abscesses and tumors, corresponding 125I-labeled antibodies served as controls. The liver uptake was similar (P = 0.76 and P = 0.12) for 99mTc or 125I labeled antinuclear antibody TNT-1 in mice bearing abscesses as well as for 99mTc-TNT-1-F(ab')2 and 125I-TNT-1-F(ab')2 in mice bearing tumors. Higher but statistically insignificant (P = 0.08, 0.18, and 0.73) urinary excretion was noted for 99mTc-antibodies. For corresponding 99mTc- and 125I-labeled antibodies, the abscess to muscle ratios (3.3 +/- 0.5 vs. 3.4 +/- 0.8) and tumor to muscle ratios (10.04 +/- 4.4 vs. 10.54 +/- 3.0) were similar. The high 99mTc-TNT-1-F(ab')2 uptake permitted excellent scintigraphic visualization of tumors whereas the nonspecific 99mTc-HSA did not (tumor/muscle ratio: 2.4 +/- 0.3). This method is simple, reliable, and adaptable to an instant labeling technique.

Determination of reduced disulfide groups in monoclonal antibodies.

Reduction of disulfide bonds to sulfhydryl groups for direct radiolabeling of antibodies for immunoscintigraphic and therapeutic applications continues to be of considerable interest. Sensitive spectrophotometric methods have been evaluated that will enable investigators to determine submicrogram quantities of cysteine units produced, for the assurance of controlled reduction. One method, which generates a cysteine-ninhydrin complex (520 nm), has a molar extinction coefficient of 30 250 and can determine 0.04 micrograms/ml cysteine units with an absorbance of 0.01. The method has been applied to determine the quantity of cysteine groups produced by the reduction of an immunoglobin G antibody with five different reducing agents in normal to five times the previously determined optimal molar ratios. The quantities of cysteine units produced from the controlled reduction from 240 micrograms immunoglobin G ranged from 0.073 +/- 0.01 to 1.07 +/- 0.04 micrograms, which were merely 0.54 +/- 0.08% to 7.9 +/- 0.28% of the total available disulfide groups in the protein.