Objective. To determine how often neonates with Enterobacteriaceae (ENTB) bacteremia can be treated successfully without removing central venous catheters (CVCs). Methods. A retrospective cohort study was conducted of ENTB bacteremia and CVCs in infants in a neonatal intensive care unit during a 7-year period (1994–2000). Cases of ENTB bacteremia were identified from a microbiology database and limited to late-onset cases occurring after 3 days of age. Results. There were 53 cases of ENTB bacteremia in infants with CVCs. Blood cultures were positive for ENTB within a median of 10 hours (range: 5–43). Timing of CVC removal was at the discretion of attending neonatologists. Fifteen cases had early-removal CVC (ER-CVC) within 2 days, and 38 cases had late-removal CVC (LR-CVC) >2 days after the first positive blood culture for ENTB. There were no significant differences between infants in the ER-CVC and LR-CVC groups for case fatality, recurrence, or duration of ENTB bacteremia. Although 16 (42%) of 38 (95% confidence interval [CI]: 26%–59%) LR-CVC cases required CVC removal to resolve ENTB bacteremia, 17 (45%) of 38 (95% CI: 29%–62%) LR-CVC cases were treated successfully without removal of CVCs. ENTB bacteremia was successfully treated without CVC removal in 85% of 13 LR-CVC cases with 1 day of bacteremia in contrast to 24% of 25 LR-CVC cases with >1 day of bacteremia (relative risk: 3.5; 95% CI: 1.7–7.4). CVC removal was required to resolve ENTB bacteremia in 9 (82%) of 11 LR-CVC cases with severe thrombocytopenia compared with 7 (32%) of 22 LR-CVC cases without severe thrombocytopenia (relative risk: 2.6; 95% CI: 1.3–5.0). Conclusions. Retention of CVCs was successful in 45% of cases of ENTB bacteremia in which it was attempted, but success was unlikely when bacteremia lasted >1 day. ENTB bacteremia cases associated with severe thrombocytopenia rarely resolved unless CVCs were removed.
Thick myosin filaments, in addition to actin filaments, were found in sections of glycerinated chicken gizzard smooth muscle when fixed at a pH below 6.6. The thick filaments were often grouped into bundles and run in the longitudinal axis of the smooth muscle cell. Each thick filament was surrounded by a number of thin filaments, giving the filament arrangement a rosette appearance in cross-section. The exact ratio of thick filaments to thin filaments could not be determined since most arrays were not so regular as those commonly found in striated muscle. Some rosettes had seven or eight thin filaments surrounding a single thick filament. Homogenates of smooth muscle of chicken gizzard also showed both thick and thin filaments when the isolation was carried out at a pH below 6.6, but only thin filaments were found at pH 7.4. No Z or M lines were observed in chicken gizzard muscle containing both thick and thin filaments. The lack of these organizing structures may allow smooth muscle myosin to disaggregate readily at pH 7.4.
Fresh taenia coli and chicken gizzard smooth muscle were studied in the contracted and relaxed states. Thick and thin filaments were observed in certain (but not all) cells fixed in contraction. Relaxed smooth muscle contained only thin filaments. Several other morphological differences were observed between contracted and relaxed smooth muscle. The nuclear chromatin is clumped in contraction and evenly dispersed in the relaxed state. The sarcolemma is more highly vesiculated in contraction than in relaxation. In contraction, the sarcoplasm also appears more electron opaque. Over-all morphological differences between cells fixed in isometric and in unloaded contraction were also noticeable. The results suggest a sliding filament mechanism of smooth muscle contraction; however, in smooth muscle, unlike striated muscle, the thick filaments appear to be in a highly labile condition in the contractile process. The relation between contraction and a possible change in pH is also discussed.
The Gestalt Photo Mapping System is made up of the GPM II and GPM Plotting System. The GPM II is a computer-controlled, auto-correlating, analytical photomapper. It is composed of two scanners, an automatic image correlator, a control computer, an operator's console, and one or two printers. A typical stereomodel is completed automatically in less than an hour and a half after a 10 minute operator-assisted analytical orientation. Principal topographic output consists of a 700,000-point digital terrain model (DTM) on magnetic tape: Planimetric output consists of an orthophoto on 20 X 25 cm stable-base film. The GPM Plotting System is an off-line automatic DTM processing system. It consists of a disk-based minicomputer and plotter. Smoothed contours and slope maps may be plotted at map scale with annotation in less than an hour and a half. A GPM III orthophoto and GPM Plotting System contours may be combined without editing by using conventional photographic techniques to produce a reproduction-quality contoured orthophot map in less than a day. /Author/
