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Biomedical subjects

T R Johnson

Publications and source records attributed to T R Johnson.

At least 163 records · Page 9Linked to original sources
PubMed1983

Large-scale isolation of plasmid DNA and purification of lambda phage DNA using hydroxylapatite chromatography.

A rapid and relatively simple procedure for purifying large quantities of plasmid DNA is described. Plasmid thus purified contains no detectable chromosomal DNA and little RNA or protein. The procedure combines alkaline denaturation and hydroxylapatite chromatography and utilizes an improved method of separating DNA from RNA. It was observed that the phosphate concentrations at which previously bound DNA as well as RNA elute from hydroxylapatite changed markedly as a function of urea concentration. In the presence of urea concentrations higher than 4 M, the ranges of phosphate concentration over which DNA and RNA elute show no overlap. This permits efficient washing of hydroxylapatite-bound DNA under conditions which should remove all bound RNA. lambda Phage DNA is also easily eluted from hydroxylapatite under the conditions used.

Adsorption↗
PubMed1983

Mid-trimester fetal ultrasound: diagnostic dilemmas.

Two cases are reported in which an unusual ultrasound finding preceded diagnostic amniocentesis and led to further work-up. In both cases a decision was made to terminate the pregnancy. One fetus in which a neck mass was detected by ultrasound was shown to be normal on post-mortem examination. The second fetus was aborted because of Rh sensitization and had the abnormality seen by ultrasound. However, this lesion, calcified intrahepatic plaques, had no presumed pathological significance. These cases suggest caution in the interpretation of results obtained with the new technologies used for prenatal diagnosis.

Abortion, Therapeutic↗
PubMed1983

Pregnancy and maternal proximal focal femoral deficiency. A case report.

Proximal focal femoral deficiency is a rare form of disproportionate dwarfism. This case report illustrates the common complications associated with it: ambulatory difficulty, abdominal and back pain and absolute cephalopelvic disproportion. The common findings of pelvic contraction in disproportionate dwarfs generally requires delivery by cesarean section.

Adult↗
PubMed1982

Proteins associated with poly(A)+RNA of cockerel liver: effects of estradiol stimulation.

The protein population of poly(A)-containing messenger ribonucleoprotein (mRNP) from cockerel liver was analyzed before and after estradiol induction. Polysomal and free mRNP were isolated by thermal elution from oligo(dT)-cellulose. The proteins were separated by two-dimensional electrophoresis (of which the first dimension was a nonequilibrium pH gradient) and were visualized by silver staining. In order to determine similarities and differences between proteins of various mRNP fractions, trace amounts of 125I-labeled protein from one fraction were coelectrophoresed with stainable amounts of protein from another fraction on the same gel. Of 27 proteins analyzed, 15 were common to polysomal and free mRNP, 7 were specific to polysomal mRNP, and 5 were specific to free mRNP. Moreover, estradiol strongly influenced 11 proteins. Six proteins changed either in relative intensity or in distribution between polysomal and free mRNP fractions. Three major proteins appeared in both fractions, and two additional proteins disappeared from the free mRNP fraction after estradiol treatment. The results suggest that the protein population in polysomal mRNP is quite complex and that the profound influence of estradiol on protein synthesis in cockerel liver may be connected to changes in the protein composition of mRNP.

Animals↗
PubMed1982

An ominous undulating fetal heart rate pattern.

Three cases of severely compromised fetuses are reported in which a similar FHR tracing was observed: an undulating pattern describing a "sinusoidal" shape, a frequency of 0.5-1 cpm, amplitude of 10-15 bpm, and flattened baseline varying between 60-120 bpm. This pattern appears to differ significantly from the sinusoidal pattern described previously and appears to identify an agonal or pre-agonal fetus that nonetheless may be salvageable and, therefore, requires maximal obstetric intervention.

Adolescent↗
PubMed1982

Sonographic findings in abdominal pregnancy.

The sonographic findings in four cases of abdominal pregnancy are described and compared with similar cases reported in the literature. The findings include demonstration of an empty uterus adjacent to the bladder, absence of myometrium around the fetus, unusual fetal lie, poor definition of the placenta, and relative oligohydramnios.

Adult↗
PubMed1981

Gestational age assessment. II. Prediction from combined clinical observations.

Accurate assessment of the estimated date of confinement is a cornerstone of obstetric care. In an earlier report, we examined the time of occurrence of various historical and clinical estimators of gestational age in relation to the date of delivery. We now examine the possibility of combining multiple clinical estimators to improve the prediction of delivery date. Formulas for predicting delivery date from multiple clinical estimators were developed in a group of 418 patients who were delivered of infants weighing greater than or equal to 3,000 gm, after spontaneous onset of labor. These formulas were tested in a separate group of 107 patients who fulfilled similar criteria. In patients with a known last menstrual period, additional clinical information did not improve the prediction of delivery date; however, if the last menstrual period was uncertain or unknown, averaging the predicted delivery dates by several clinical examinations provided a prediction of delivery date as precise as if the last menstrual period were known.

Female↗
PubMed1981

Significance of the sinusoidal fetal heart rate pattern.

The sinusoidal fetal heart rate pattern has been reported to be an indication of fetal compromise. In this review of 31 cases, drawn from a total of 559 monitored cases of normal and at-risk women, only one resulted in poor outcome, and this was attributable to a difficult breech delivery. An association with administration of analgesics is confirmed. The sinusoidal fetal heart rate pattern does not appear to be uniformly associated with fetal distress. Its presence should be an indication for meticulous assessment of other electrocardiographic, biochemical, or clinical evidence of fetal status.

Analgesics↗
PubMed1981

Gestational age assessment. I. analysis of individual clinical observations.

Accurate assessment of the estimated date of confinement is a cornerstone of obstetric care. Traditionally this date has been predicted from historical and clinical examinations; however, there have been few studies of the accuracy of such predictions. Multiple estimators of gestational age were examined in 418 patients who were delivered of infants weighting larger than or equal to 3,000 gm, following spontaneous onset of labor. Mean intervals from an event to delivery were calculated for last menstrual period (284.2 days), quickening (156.3 days), first audible fetal heart tones (136.2 days), uterine fundus at the umbilicus (140.8 days), and measurements of the fundal height. The variability in each of these estimators was examined and compared. The last menstrual period, if known with certainty, is the most accurate estimator, followed by the uterus at the umbilicus, first heard fetal heart tones, fundal height, and quickening.

Adolescent↗
PubMed1981

Limited wrist arthrodesis. Part II: Intercarpal and radiocarpal combinations.

Fusion of selected bones of the carpus, occasionally combined with the radius or metacarpal bases, has been used to treat a wide variety of serious pathologic conditions of the wrist. Indications include severe localized degenerative arthritis and posttraumatic changes secondary to subluxation, dislocation, or residual instability resulting in significant pain. The procedure was performed on 28 wrists in 26 patients. There were three failures to obtain union initially, two of which united after secondary grafting procedures. All patients had less pain and most had functional, though limited, ranges of wrist motion. Limited wrist arthrodesis provides a workable alternative to complete wrist fusion and Silastic wrist arthroplasty for many wrists with localized destruction.

Adolescent↗
PubMed1981

Premature rupture of membranes and preterm labor: neonatal infection and perinatal mortality risks.

The purpose of this study was to analyze neonatal infection rates and perinatal mortality in births complicated by premature rupture of membranes (PROM) and spontaneous labor before term (less than 37 weeks' gestation). Neonatal infection occurred more commonly in preterm compared with term infants. The risk of infection due solely to PROM was insignificant compared with the risk attributable to preterm birth. Perinatal mortality and cause-specific mortality varied inversely with gestational age. These rates were not significantly different between groups with or without PROM or with or without associated development of maternal endometritis. Although the mortality due to infection was higher in preterm compared with term groups, most preterm deaths were attributed to other factors, particularly anoxia and respiratory causes. The diverse fetal risks associated with PROM and the associated maternal infection risks analyzed support expectant management when PROM occurs preterm.

Endometritis↗
PubMed1981

Premature rupture of the membranes and prolonged latency.

The aim of this retrospective study in 8320 patients with premature rupture of the membranes (PROM) was to determine the consequences of prolongation of the latent period. Among patients with pregnancies of more than 37 weeks' duration, those with PROM and latent periods of more than 1 day demonstrated an increased incidence of intrapartum fever (IPF), whereas those with latent periods of more than 3 days demonstrated a marked increase in fetal (but not neonatal) deaths. Although IPF and perinatal mortality were more common in preterm pregnancies, neither was found to increase or decrease with prolonged latency, provided differences in gestational ages and race were taken into account. In the absence of chorioamnionitis, there appears to be no benefit to delivery before 37 weeks' gestation.

Birth Weight↗