Deoxyribonucleotide synthesis in an Escherichia coli mutant (H 1491) which lacks ribonucleotide reductase subunit B2.

An iron-sensitive mutant of E. coli with a Mudl phage insertion in the nrdB gene lacks subunit B2 of the key enzyme of DNA synthesis, ribonucleotide reductase. Nevertheless, these cells are capable of growing in minimal media under anaerobic conditions, indicating a second enzyme or pathway for deoxyribonucleotide synthesis.

Duplex ultrasonography of the fetal aorta, umbilical artery, and placental arcuate artery throughout normal human pregnancy.

A cross-sectional duplex study of blood flow in the fetal aorta, umbilical artery, and arcuate arteries of 111 normal subjects was performed once at between 20 and 42 weeks gestation. Peak systolic velocity, end-diastolic velocity, mean velocity, and volume flow were measured in the fetal aorta, and systolic to diastolic (S/D) ratios were measured in all three vessels. Velocities show an inverse exponential (Y = Exp [1/X x B + C]) increase with gestational age, reaching a plateau just before term, while S/D ratios in the aorta and umbilical arteries show a linear decrease.

Atrial natriuretic peptide production in association with nonimmune fetal hydrops.

The presence and elevation of atrial natriuretic peptide in fetuses has not previously been demonstrated. This study of right atrial pacing in fetal lambs demonstrated a threefold to fourfold increase in atrial natriuretic peptide during the production of fetal hydrops. Its rate of return to a normal level paralleled the clearance of fetal hydrops.

Evaluation of fetal cardiac dysrhythmias with two-dimensional, M-mode, and pulsed Doppler ultrasonography.

Forty-three patients with fetal cardiac dysrhythmia were referred to a tertiary ultrasound department for further evaluation. The patients were subdivided according to the type of dysrhythmia diagnosed. All patients with irregular fetal heart rate had a good perinatal outcome.

Pulmonary hypoplasia testing in clinical obstetrics.

An ultrasound-based diagnostic test for predicting pulmonary hypoplasia antenatally by measurements of fetal chest circumference was applied prospectively to 45 patients at risk for developing this disorder. The outcome for the newborn infant and the autopsy findings were correlated with the antenatal prediction. The results of this test demonstrated a sensitivity and a specificity of 88% and 96%, respectively.

Doppler waveforms in the fetal aorta and umbilical artery in patients with hypertension in pregnancy.

Pulsed Doppler ultrasound assessment of blood flow was performed in the fetal aorta and umbilical arteries of 41 patients with hypertension in pregnancy. Patients were grouped according to severity of the hypertension and the presence or absence of chronic hypertension. Doppler abnormalities were seen in two patients with chronic hypertension, both of whom delivered small for gestational age infants.

Seasonal energetics of opossums (Didelphis virginiana) in Ohio.

1. Female opossums acclimatized to each of the four seasons were not significantly different (P greater than 0.05) in oxygen consumption at a Ta of 0 degrees C; the overall average was 0.

Ultrasound evaluation of tachycardia-induced hydrops in the fetal lamb.

Nonimmune hydrops was induced in six fetal lambs at 120 days' gestation by right atrial pacing at 300 beats/min. Biochemical, hemodynamic, and Doppler parameters were observed and monitored by real-time ultrasound during the creation (18 to 42 hours) and resolution of hydrops. The significant changes seen were hypoproteinemia (34.

Doppler ultrasound prediction of fetal outcome in twin pregnancies.

The usefulness of pulsed Doppler ultrasound in predicting twin pregnancies destined for unsatisfactory outcomes was examined in 30 twin pregnancies. Fetal flow velocity waveform analysis (systolic/diastolic ratio and pulsatility index) and quantitative analysis in the descending aorta and umbilical artery demonstrated good sensitivity and specificity when compared with biparietal diameter and abdominal circumference measurements. This technique shows some promise as a useful adjunct in the management of twin pregnancies.

Ultrasound prediction of pulmonary hypoplasia.

Normograms for ultrasound-measured fetal chest and heart circumferences were constructed from 83 normal pregnancies of 24 to 39 weeks' duration. Of six cases at risk for pulmonary hypoplasia, all of whom ultimately proved to have the condition, four fell below the fifth percentile for chest circumferences. Both cases in which the chest circumference was within the normal range had pleural effusions.

Effects of removal in late pregnancy of the corpus luteum, graafian follicle or ovaries on plasma progesterone, oestradiol, LH, parturition and post-partum oestrus in the tammar wallaby, Macropus eugenii.

Concentrations of oestradiol-17 beta, progesterone, and luteinizing hormone (LH) were measured in plasma collected at 6- to 12-h intervals from tammars around the time of parturition and post-partum oestrus. Parturition occurred on Day 26 or 27 after reactivation of lactation-delayed pregnancy and coincided with a precipitous decline in progesterone levels. A sharp rise in oestradiol, from basal concentrations of less than 10 pg/ml to a peak of 13 to 32 pg/ml, as well as oestrus, followed the drop in progesterone by 8.

Oestradiol in follicular fluid and in utero-ovarian venous and peripheral plasma during parturition and postpartum oestrus in the tammar, Macropus eugenii.

Oestradiol-17 beta was measured in plasma and follicular fluid by a radioimmunoassay validated for the tammar. Plasma was sampled from the peripheral circulation and both utero-ovarian veins to assess the contribution of oestradiol from the corpus luteum in one ovary and from the Graafian follicle in the other during late pregnancy, parturition, post-partum oestrus and ovulation. Concentrations of oestradiol in the peripheral plasma and in the vein draining the CL remained less than 5 pg/ml on all days except the day of parturition, when they were 12.

In utero evaluation of fetal cardiac structure: a preliminary report.

Fetal echocardiography as a tool for the prenatal diagnosis of cardiac structural abnormalities was utilized in 27 consecutive patients who were referred for evaluation. Four abnormalities were recognized prenatally and confirmed postnatally. A fifth was identified postnatally.

Luteal and follicular populations in the ovary of the opossum (Didelphis virginiana) after ovulation.

The maximum diameters of all luteal and antral follicular structures were measured in opossum ovaries on Days 3, 7 and 11 after oestrus, and follicles were classed as developing or atretic. Ovarian weights and luteal diameters were equivalent in comparisons of pregnant and non-pregnant animals on each day. The number of CL (range 45-85) per animal per cycle indicated a very high ovulation rate for a mammal.

Cross-sectional echocardiographic diagnosis and subclassification of univentricular hearts: imaging studies of atrioventricular valves, septal structures and rudimentary outflow chambers.

We reviewed anatomic observations (surgical or autopsy), angiograms and echocardiograms from 44 patients with documented univentricular hearts. Thirty-three patients had univentricular heart of left ventricular type with an outflow or rudimentary chamber. Five had univentricular heart of right ventricular type, and six had univentricular heart of indeterminate types without a rudimentary chamber.

Husbandry of a small breeding colony of opossums (Didelphis virginiana).

A small breeding colony of opossums was established in a semi-enclosed structure. Minor modifications of pre-existing pens permitted efficient and productive management of the opossums. Dry dog food was provided, and large amounts of shredded paper was used for nesting material.

The atrioventricular junction in the univentricular heart: a two-dimensional echocardiographic analysis.

The atrioventricular junction of 40 patients with univentricular heart was evaluated by two-dimensional echocardiography. The apical 4 chamber view optimally imaged the atrioventricular junction, and allowed determination of the type of atrioventricular connection: double inlet, common atrioventricular orifice, and absent right or left atrioventricular connection. When double inlet to 1 ventricle was demonstrated, the 4 chamber view allowed immediate comparison of the form and function of the right and left atrioventricular valves.

Uterine histology and reproductive cycles in pregnant and non-pregnant opossums, Didelphis virginiana.

Uteri (N = 18) were collected on Days 3, 7, and 11 of the oestrous cycle or gestation. Reproductive cycles were monitored by vaginal cytology in captive opossums. There was no difference in length of cycles between reproductive states (29.

Computerized axial tomography to demonstrate occult fractures of the acetabulum in children.

Following hip trauma in children an intra-articular osteocartilaginous fragment may be retained within the hip joint. This fragment may not be visualized by plain films or arthrography. However, computerized tomography clearly demonstrated such fragments in the two children with post-traumatic painful hips reported in this paper.

Estradiol and progesterone profiles indicate a lack of endocrine recognition of pregnancy in the opossum.

Concentrations of estradiol and progesterone in blood collected during the 12.5-day gestation period of the Virginia opossum were not significantly different from those during equivalent days of the estrous cycle. Progesterone was correlated with an index of corpora luteral mass.