BACKGROUND: We compared outcomes between neonates receiving either single course, multiple courses, or no antenatal glucocorticoid exposure. METHODS: We retrospectively identified neonates whose mothers received a single course (SIN) of dexamethasone, multiple (2-3) weekly courses (MULT), or no (NO) glucocorticoids. Multiple gestations and infants with chromosomal abnormalities or not receiving a full course of antenatal dexamethasone were excluded from the study. The incidences of the following outcomes were examined: respiratory distress syndrome (RDS), Grades III or IV intraventricular hemorrhage (IVH), bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), retinopathy of prematurity (ROP), sepsis, and in-hospital death. Means were compared with analysis of variance and outcome variable frequencies with chi-square test. RESULTS: A total of 147 infants were included in the analysis. There were no differences in the gestational age or growth parameters among the groups. As anticipated, infants exposed to antenatal glucocorticoids had a significantly lower incidence of morbidities (BPD, NEC, and IVH) than the unexposed infants. There were no differences in the incidence of RDS, IVH, BPD, NEC, ROP, PDA, sepsis, or death between the SIN and MULT groups. CONCLUSION: A single course of antenatal glucocorticoid therapy is associated with improved neonatal outcomes in infants less than 30 weeks' gestation. Multiple courses were not shown to confer additional benefits, but further investigation is required to definitively address the need for weekly treatment.

Bronchopulmonary Dysplasia↗

PubMedDate not supplied

A model for the mobility of single-stranded DNA in capillary gel electrophoresis.

The electrophoretic mobility of single-stranded DNA in denaturing polyacrylamide gel-filled capillaries is analyzed as a function of the applied electric field. The resultant mobility plots are complex functions of the fragment size and electric field. Traditionally, these plots are separated into three mobility regimens corresponding to Ogston sieving, reptation without stretching and reptation with stretching theories. However, none of these theories accurately models the variations in mobility that we observe with electric field strength. As a result, we propose a modification of the Ogston sieving theory which accounts for the stretching of migrating DNA molecules in the direction of the electric field. This theory assumes that the applied electric field in conjunction with the gel matrix distorts the DNA, altering the effective size of the migrating molecule. The stretched DNA offers a smaller cross-section to the gel pore and thus sieves as though it were a smaller molecule. In this modified Ogston theory, the electrophoretic mobility depends only on the applied electric field, the size of the fragment, and constants which are independent of size and field strength. The modified Ogston equation accurately predicts the mobilities of DNA fragments in all three mobility regimes, providing a single, simple model to account for all of the observed behavior.

DNA, Single-Stranded↗

PubMedDate not supplied

Separating field strength, temperature, and pulsing effects in pulsed field electrophoresis.

The utility of pulsed field electrophoresis for DNA sequencing is investigated. Previous studies have indicated a beneficial retardation of sequencing fragments when pulsed fields are employed. The interpretation of these results is complicated, however, by concomitant variations in electric field strength and/or temperature. Methods are presented here permitting discrimination of such mobility effects due to pulsing, field strength, and temperature. It is demonstrated that under the conditions employed here, observed mobility effects are due to electric field variations rather than pulsing. These conditions thus correspond to the low frequency/small molecule limit. The effect of temperature is estimated from the steady state solution to the heat conduction equation under appropriate boundary conditions. No temperature effect upon mobility is operative in the thin gel system employed, due to the high efficiency of heat transfer. However, it is shown that in conventional gel systems large temperature-related mobility effects can occur. These methods for dissecting and understanding mobility effects in pulsed field electrophoresis are expected to be of general utility.

Base Sequence↗

PubMedDate not supplied

All through the night.

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Aged↗

PubMedDate not supplied

Medical utilisation and costs in panic disorder: a comparison with social phobia.

There is considerable evidence that people with panic disorder utilise the physical health care system more frequently than people in the general community and so incur for themselves, and impose on the public health care system, considerably greater costs. Although this is probably because of specific characteristics to do with panic disorder, it may also be a function of having any anxiety disorder where panic is prominent. This study represents one of the few comparisons of medical utilisation and costs incurred by people with panic disorder to those incurred by people with another anxiety disorder, in this case, social phobia. Before treatment, 41 people with panic disorder, 15 with social phobia and 43 nonanxious controls were interviewed about their use of the medical care system over the previous 12 months. As expected, people with panic disorder had significantly higher utilisation rates than either the nonanxious controls or the socially phobic subjects, and incurred substantially higher costs. Adequate screening for panic disorder at the primary medical care level together with appropriate treatment referral therefore have the potential to substantially reduce the personal and community costs incurred by people with panic disorder.

Adult↗

PubMedDate not supplied

Individual lipid and proximate analysis of various foods. 3. Potato chips and corn snack foods.

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Fats↗

PubMedDate not supplied

Fluorescence detection in automated DNA sequence analysis.

We have developed a method for the partial automation of DNA sequence analysis. Fluorescence detection of the DNA fragments is accomplished by means of a fluorophore covalently attached to the oligonucleotide primer used in enzymatic DNA sequence analysis. A different coloured fluorophore is used for each of the reactions specific for the bases A, C, G and T. The reaction mixtures are combined and co-electrophoresed down a single polyacrylamide gel tube, the separated fluorescent bands of DNA are detected near the bottom of the tube, and the sequence information is acquired directly by computer.

Automation↗

PubMedDate not supplied

Postnatal thyroxine supplementation in infants less than 32 weeks' gestation: effects on pulmonary morbidity.

OBJECTIVE: Transient hypothyroxinemia in premature newborns has been linked with poor neonatal outcomes. We designed this study to evaluate the effects of early thyroxine (T4) administration in the premature infant. STUDY DESIGN: A total of 49 newborns less than 32 weeks' gestation, were randomized in a double-blind, placebo-controlled trial. Within the first 48 hours of life, T4 (10 or 20 micrograms/kg; intravenous or through nasogastric tube, respectively) was administered for a total of 21 days. Chronic lung disease, the primary outcome variable, was defined by oxygen dependency at 28 days of life. RESULTS: The incidence of chronic lung disease, death, grade III or IV intraventricular hemorrhage, periventricular leukomalacia, and sepsis was not different in the placebo and treated groups. CONCLUSION: Early T4 supplementation in preterm newborns less than 32 weeks' gestation does not decrease the incidence of chronic lung disease or other complications of prematurity.

Bronchopulmonary Dysplasia↗

PubMedDate not supplied

In vitro assessment of the Milwaukee Heart and right to left balance.

A new, electrically powered, total artificial heart, the Milwaukee Heart, has been developed. This device is undergoing testing in vitro. The unidirectional motion of the brushless DC motor (BDCM) affords easier motor control and reduces energy demand. Motors with a unidirectional motion have a longer life than those with bidirectional motion. This device requires less power due to the highly efficient mechanical design. It consumes 6.5 W of power at an average flow of 5 L/min into 100 mmHg of mean aortic pressure and 20 mmHg of mean pulmonary pressure. Pumping at 8 L/min it requires 9.6 W of power. The maximum pump flow is 10 L/min and overall efficiency is 20%. A slotted optocoupler is used to determine the position of the pusher plate at the start of left systole. The number of revolutions that the BDCM makes is counted from this position. There are 50 revolutions of the BDCM per stroke (using a 50:1 gear reducer connected to the motor). The position of the pusher plate is determined from the number of BDCM revolutions. Based on where the pusher plate encounters resistance from the bladder, the force on the left pump is increased or decreased. Left to right balance has been achieved by reducing the size of the right pusher plate in conjunction with varying right stroke volume. In vitro tests show that this new, electrically powered artificial heart provides reliable performance and satisfactory hemodynamic results.

Biomechanical Phenomena↗

PubMedDate not supplied

Is it possible to perform immediate cardiac assist using untrained latissimus dorsi muscle in a work-rest regimen?

The authors investigated what contractile force (CF) could be obtained from unconditioned latissimus dorsi muscle immediately after mobilization and for the 2 week vascular period of recovery. Latissimus dorsi muscle mobilization was performed on seven adult (4 experimental and 3 control) sheep leaving only the pedicle and the peripheral muscle intact. Telectronics stimulators (Myostim 7220; Teletronics Pacing Systems, Inc, Englewood, CO) were implanted. Immediately after mobilization 11-35% of the initial CF was lost. A 30 min fatigue test was performed 1 hr after mobilization (20 g/kg preload, 10 V, 10 Hz, 15 BPM, 6 impulses per burst) using a 1 min work-1 min rest regimen. Two sheep lost 2-12% of initial CF; two increased CF by 14-24%. At the end of the fatigue test, CF consisted of 74-89% of immobilized CF. Electrical stimulation training of the muscle was then initiated with the following regimen in the experimental animals only: 15 BPM, single impulses, 5 V, 10 Hz. Every day the muscle was exercised using a work-rest regimen to mimic cardiac assist, starting with 20 min on day 2, and increasing by 2 min per day until a total of 50 min was reached on day 16. All animals were retested for CF using a 42 min fatigue test on days 6, 11, and 16. On day 6, there was no fatigue evident in the experimental group during the 42 min test. CF after testing was 59-81% (mean 67%) of initial data. In the control group (animals with no electrical stimulation training protocol), CF decreased by 11% (from 64 to 53%). On day 11, there was no fatigue evident in the experimental group; CF in all animals increased by 2-8%. On day 16, there was also no fatigue evident in the experimental group; CF increased by 0-9%. An additional 20 min of continuous contraction (15 BPM) fatigue testing was performed on the muscle without rest between the tests. No fatigue was evident at the end of testing. Light microscopic analysis of latissimus dorsi muscle biopsy specimens taken on the days of testing showed no evidence of necrotic damage. Our investigations suggest that it may be possible to start muscle transformation immediately after mobilization and use the untrained latissimus dorsi muscle for cardiac assist immediately after surgery for short periods.

Animals↗