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Biomedical subjects

T R Johnson

Publications and source records attributed to T R Johnson.

At least 91 records · Page 5Linked to original sources
PubMed1994

Maternal perception and Doppler detection of fetal movement.

Fetal movement can be used as a tool for assessment of prenatal well-being. Maternal perception of fetal movement, using a formal graphic "count-to-ten" system is often used as an adjunct in high risk and normal pregnancies. Doppler detection of fetal movement is a newly introduced, easy to perform methodology. Identification of coupling fetal heart rate accelerations to fetal movement as an aid for nonstress testing and recognition of fetal behavior, fetal behavioral states and cycling between states, is a current clinical application of this new technique.

Female↗
PubMed1994

Uterine rupture associated with recent antepartum cocaine abuse.

BACKGROUND: The diagnosis of uterine rupture is aided by the identification of risk factors, such as oxytocin administration. In several experiments, cocaine has been shown to stimulate uterine contractility. Complications from cocaine abuse during pregnancy have increased dramatically in the United States, and cocaine may increase the risk for uterine rupture. CASES: Two cases of uterine rupture were associated with recent cocaine abuse. CONCLUSION: These cases and recent experiments on the effect of cocaine on the pregnant uterus suggest that antepartum cocaine abuse may increase the risk of uterine rupture.

Adult↗
PubMed1993

Treatment and prevention of rat glioblastoma by immunogenic C6 cells expressing antisense insulin-like growth factor I RNA.

Rat C6 glioma cells express insulin-like growth factor I (IGF-I) and form rapidly growing tumors in syngeneic animals. When transfected with an episome-based vector encoding antisense IGF-I complementary DNA, these cells lost tumorigenicity. Subcutaneous injection of IGF-I antisense-transfected C6 cells into rats prevented formation of both subcutaneous tumors and brain tumors induced by nontransfected C6 cells. The antisense-transfected cells also caused regression of established brain glioblastomas when injected at a point distal to the tumor. These antitumor effects result from a glioma-specific immune response involving CD8+ lymphocytes. Antisense blocking of IGF-I expression may reverse a phenotype that allows C6 glioma cells to evade the immune system.

Animals↗
PubMed1993

Transgenic strategies in reproductive endocrinology.

The present discussion surveys some of the recently published studies utilizing transgenic strategies to address questions in reproductive endocrinology. Beginning with a brief introduction of the transgenic method itself, the following areas are covered: 1. Sexual development and Müllerian-inhibiting substance; 2. Hypogonadal mice and hypothalamic GnRH; 3. The GnRH neuron: generation of immortalized rare cell types; 4. Glycoprotein hormones: immortalized cells, development and evolution; 5. Growth hormone and reproduction; and, 6. Gestation and the insulin-like growth factors. In each section, the discussion attempts to be integrative with respect to the significance of the results to physiological, cellular and molecular biology. We believe this approach is appropriate, as transgenic science itself is necessarily an integration of all of these levels of investigation and participation from those working at all levels is needed.

Animals↗
PubMed1993

Elevated circulating thrombomodulin in severe preeclampsia.

A relationship between serum thrombomodulin and preeclampsia was investigated. In women with severely preeclamptic pregnancies, serum thrombomodulin levels were found to be significantly elevated as compared with those of matched control subjects (p < 0.005). Serum thrombomodulin levels correlated positively with serum creatinine (r = 0.854, p < 0.0001) and uric acid levels (r = 0.784, p < 0.001).

Adult↗
PubMed1993

The ideal twin pregnancy: patterns of weight gain, discordancy, and length of gestation.

OBJECTIVE: Our purpose was to evaluate factors associated with the best intrauterine growth and lowest morbidity among twins ("ideal twin pregnancy"). STUDY DESIGN: A historic prospective study of 163 twin births was performed. Ten models were formulated with multiple regression and multivariate logistic regression. RESULTS: In the models of birth weight, gestations of 28 to 36 and 39 to 41 weeks, black race, > or = 15% discordancy, and smoking were all significant negative factors. The pattern of early low weight gain (< 0.85 pounds per week before 24 weeks) and late low weight gain (< 1.0 pound per week after 24 weeks) was negatively associated with all eight models of intrauterine growth. CONCLUSIONS: The best intrauterine growth and lowest morbidity is achieved earlier for twins than for singletons. Using length of stay and growth retardation criteria, nearly 70% of "ideal" twin pregnancies were between 35 and 38 weeks. In addition, poor weight gain and poor patterns of weight gain were associated with all measures of intrauterine growth and adverse pregnancy outcomes.

Baltimore↗
PubMed1993

Effect of rapid intravenous crystalloid infusion on uteroplacental blood flow and placental implantation-site oxygen delivery in the pregnant ewe.

OBJECTIVE: Our purpose in this study was to investigate the effects of rapid intravenous crystalloid infusion on placental implantation-site blood flow and oxygen delivery in the near-term pregnant ewe. STUDY DESIGN: Maternal left ventricular, femoral arterial and venous, and bilateral fetal hind limb arterial catheters were placed in nine near-term ewes 5 days before the start of the study. Maternal and fetal arterial blood gas values, maternal hemodynamic measurements, and maternal organ blood flows (microsphere technique) were obtained before and after the intravenous infusion of 2.0 to 2.5 L of normal saline solution. Myometrial and placental implantation-site vascular resistances and oxygen delivery were calculated. The t test for paired comparisons was used for statistical analysis, with p < or = 0.05 considered significant. RESULTS: Significant postinfusion increases in maternal mean arterial pressure, placental implantation-site blood flow, and skin, skeletal muscle, and renal blood flows were recorded. In the six animals that demonstrated a fall in hemoglobin concentration, a significant increase in placental implantation-site oxygen delivery and a significant decrease in placental implantation-site vascular resistance were also seen. No significant changes were seen in myometrial blood flow or myometrial vascular resistance. CONCLUSION: Rapid intravenous crystalloid infusion selectively increases placental implantation-site blood flow in the near-term pregnant ewe and may improve oxygen delivery to the fetus, especially if hemodilution occurs.

Animals↗
PubMed1993

Effect of fetal movement on the amniotic fluid index.

OBJECTIVES: Fetal movement has been shown to change the size and location of amniotic fluid pockets during measurement of the amniotic fluid index. The effect of redistributing the fixed intrauterine fluid volume on the amniotic fluid index is unknown. Therefore we tested the hypothesis that the amniotic fluid index was unaffected by fetal movement. STUDY DESIGN: A single examiner prospectively determined the amniotic fluid index before and after three discrete episodes of fetal movement during 96 biophysical profiles. A reliable blinded examiner provided a second postmovement measurement as a control. Data were analyzed by the paired t test. RESULTS: The mean change in the amniotic fluid index after fetal movement was 1.5 +/- 0.1 cm and 2.5 +/- 0.2 cm for postmovement determinations by the same examiner and blinded observer, respectively (p < 0.001). CONCLUSION: Interobserver and intraobserver variation can account for the change in the amniotic fluid index after fetal movement.

Amniotic Fluid↗
PubMed1993

Nutrient digestion, nitrogen, and amino acid flows in lactating cows fed soybean hulls in place of forage or concentrate.

Five Holstein cows in early lactation were used in a 5 x 5 Latin square design to study substitution of soybean hulls for portions of forage or concentrate in diets. The control diet consisted of (DM basis) 10% alfalfa hay, 40% corn silage, 25% high moisture corn, 23% protein supplement, and 2.3% vitamins and minerals. Soybean hulls were used to replace approximately 25 and 50% of the forage or concentrate DM in the control ration. The DMI decreased linearly as soybean hulls replaced forage. The DM and OM flow to the duodenum and apparent and true digestion of OM in the stomach were similar among treatments. Ruminal pH was similar among treatments, but concentrations of NH3 N decreased linearly when soybean hulls replaced forage. Total VFA concentrations were similar when soybean hulls replaced forage but showed a positive quadratic response when soybean hulls replaced concentrate. Microbial N averaged 59% of NAN flow and showed a negative quadratic response when soybean hulls replaced concentrate. Flows of total AA and total essential AA to the duodenum were not altered when soybean hulls were fed. Yields of milk and milk components were similar among treatments; hulls can be used effectively to replace forage or concentrate in lactation diets.

Amino Acids↗
PubMed1993

Multiple pregnancy.

The incidence of multiple gestations has increased markedly over the past decade. This review will focus on new interventions and techniques such as selective fetal reduction, optimizing maternal weight gain, bed rest, home uterine monitoring, ultrasound, and Doppler velocimetry, which have been employed to improve outcomes in these pregnancies.

Abortion, Therapeutic↗
PubMed1992

Loss of tumorigenicity of rat glioblastoma directed by episome-based antisense cDNA transcription of insulin-like growth factor I.

Malignant glioma is the most common brain tumor. The molecular basis of glioma tumorigenicity has not been defined. Cultured glioma cells accumulate high levels of insulin-like growth factor I (IGF-I) transcripts. We asked whether IGF-I expression is coupled to tumorigenicity, using a combined in vivo/in vitro system employing antisense RNA for IGF-I. An antisense IGF-I expression construct in an expression vector that incorporates Epstein-Barr virus replicative signals and the ZnSO4-inducible metallothionein I transcriptional promoter was assembled. Stable glioma transfectants were derived from C6 glioma cells, which constitutively express IGF-I. B-104 neuroblastoma cells, derived originally from the same tumor but not expressing IGF-I, were also transfected as controls. In the absence of ZnSO4, the C6 transfectants expressed high levels of IGF-I mRNA and protein as detected by in situ hybridization and immunocytochemistry, respectively. Addition of ZnSO4 in the culture medium resulted in high levels of antisense transcript accumulation and dramatically decreased levels of endogenous IGF-I mRNA and IGF-I protein. Subcutaneous injection of either nontransfected C6 parental cells or C6 cells transfected with vector without IGF-I sequences into rats resulted in large tumors after 2 weeks, as did transfected and nontransfected B-104 cells. However, the rats injected with transfected C6 cells yielded no tumors after 40 weeks of observation. Two weeks after injection of the transfected C6 cells a small cyst was apparent in six rats. Histologic sections revealed a few glioma cells infiltrated by a large number of mononuclear cells. No infiltration of mononuclear cells was apparent in the glioma tumors resulting from injection of parental (nontransfected) cells, suggesting that the parental cells, but not the antisense IGF-I transfectants, escape the host immune response.

Animals↗
PubMed1992

The third IGF-II promoter specifies transcription of three transcripts out of five in human placenta.

Insulin-like growth factor-II (IGF-II) mRNA exists as multiple transcript size classes, such as 6.0, 5.3, 4.9, 3.2, and 2.2 kb mRNAs in various human tissues. Three different promoters, 2 different polyadenylation sites, and alternative splicing are involved in producing these multiple transcripts. Initiation of transcription at the 3 different promoters results in multiple mRNAs which contain identical coding regions but different 5'-untranslated regions (5'-UTRs). The first promoter is thought to direct expression of 5.3 kb mRNA in adult human liver. The second promoter region directs expression of 6.0, 3.2, and 2.2 kb mRNAs in human fetal tissues and several adult nonliver tissues. The third promoter specifies transcription of a 4.9 kb mRNA in various tissues. We isolated and sequenced a cDNA clone (pIGF-II-1-70) from a human placental cDNA library, which contains the IGF-II coding region and the 5'-UTR associated with the third promoter. By using a 5'-UTR-specific probe from the clone, we found that this third 5'-UTR is contained in the IGF-II mRNA of 2.2 kb and is absent in the 3.2 kb IGF-II mRNA. We also found an 0.9 kb transcript expressed in placenta, which hybridized strongly to the third 5'-UTR specific probe but not to IGF-II coding region probes. This finding might indicate the existence of an mRNA encoding an IGF-II-associated peptide.

Base Sequence↗
PubMed1992

A randomized trial of prostaglandin E2 in a controlled-release vaginal pessary for cervical ripening at term.

OBJECTIVE: The purpose of this study was to determine if prostaglandin E2 in a controlled-release vaginal pessary can produce cervical ripening at term. STUDY DESIGN: This was a double-blind, randomized, placebo-controlled study conducted at a university center and involving 81 patients with 42 receiving active agent. Categoric data were analyzed by Pearson's chi 2 or logistic regression. Continuous variables were analyzed by analysis of variance and the F test. RESULTS: Prostaglandin E2 was significantly better than placebo at cervical ripening and at decreasing the time to rupture of membranes, the time to onset of labor, the need to give oxytocin, and the time to vaginal delivery. Multiparous women benefitted more than primiparous ones. The cesarean section rate decreased only for multiparous women. Uterine hyperstimulation occurred only with prostaglandin E2 and after the onset of labor. CONCLUSIONS: Prostaglandin E2, when administered in a controlled-release vaginal pessary, is affective in producing cervical ripening at term. This agent should be used on inpatients who are under continuous monitoring and it should be removed at the onset of labor.

Cervix Uteri↗
PubMed1992

Population differences of fetal biophysical and behavioral characteristics.

Population differences in nonstress test reactivity have been reported with a threefold increase in the likelihood of nonreactive nonstress tests observed in black fetuses as compared with white fetuses. We analyzed fetal behavioral states and fetal heart rates in 14 black and 15 white fetuses at term to explain this observed difference in nonstress test reactivity. Two-hour Doppler and real-time ultrasonographic examination of each patient revealed no differences in percent time spent in the four behavioral states between the two populations. A 9.5 beats/min difference between black and white fetuses was found. The higher baseline heart rate of the black fetuses persisted in each behavioral state and may affect nonstress test reactivity because of rate-dependent decreases in short-term variability and rate-dependent limitations of maximal acceleration amplitude.

Behavior↗
PubMed1992

Regulation of transcription by translational components in coupled translation-transcription cell-free system.

A coupled translation-transcription cell-free system was established from eukaryotic cells. The biosynthetic activity of this coupled system closely resembles the synthetic behavior of cells in vivo, and exhibits regulatory phenomena similar to that of intact cells. The translational system consists of rabbit reticulocyte lysate, or its components fractionated by centrifugation. The transcriptional portion consists of cockerel liver nuclei. Incorporation of amino acids into protein by the coupled system is linear for hours. Similarly, transcription in the coupled system is continuous for hours and is proportional with time. More than 90% of the transcriptional products are secreted into the incubation medium. The components of the translational system influence and regulate transcriptional activities. In the presence of ribosomes the nuclei transcribe mostly poly(A)+ RNA with alpha-amanitin sensitivity consistent with activation of RNA polymerase II. Hybrid selection experiments demonstrate authentic preproalbumin mRNA among the transcriptional products. The putative mRNA secreted into the medium in the coupled system is found on polysomes, indicating translation of de novo synthesized message. Addition of excess reticulocyte mRNP to the medium of the coupled system results in transcription of primarily ribosomal RNA, 5S RNA, and tRNA, the products of RNA polymerases I and III. These activities closely imitate the behavior of liver in vivo under conditions of nutritional shifts or hormonal influences. The coupled system transcribes, processes, and transports substantial quantities of RNA, about 1.6 micrograms/10(6) nuclei/h. Thus, a coupled system has been established that lends itself to the exploration of regulatory interactions of cell components as it appears to closely resemble the in vivo situation.

Animals↗