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Biomedical subjects

T R Johnson

Publications and source records attributed to T R Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1996

Fetal neurobehavioral development.

The ontogeny of fetal autonomic, motoric, state, and interactive functioning was investigated longitudinally in a sample of 31 healthy fetuses from 20 weeks through term. Fetal heart rate and movement data were collected during 50 min of doppler-based fetal monitoring at 6 gestational ages. Measures of fetal heart rate and variability, activity level and vigor, behavioral state, and reactivity were derived from these digitized data. Weighted least squares analyses were conducted to model the developmental patterns and to examine the role of maternal and fetal covariates. With advancing gestation, fetuses displayed slower heart rate, increased heart rate variability, reduced but more vigorous motor behavior, coalescence of heart rate and movement patterns into distinct behavioral states, and increasing cardiac responsivity to stimulation. Male fetuses were more active than female fetuses, and greater maternal stress appraisal was associated with reduced fetal heart variability. An apparent period of neurobehavioral transition exists between 28 and 32 weeks. Fetal research methods are evaluated.

Adult↗
PubMed1996

Fetal antecedents of infant temperament.

This study established the emergence of stable individual differences in neurobehavioral functioning prior to birth and examined their relation to subsequent infant temperament. Fetal heart rate and movement were recorded longitudinally for 31 fetuses at 6 gestational ages beginning at 20 weeks' gestation. Maternally reported temperament data were collected at 3 and 6 months. Moderate stability in all measures except reactivity was apparent at some time before birth. By 36 weeks, fetal neurobehavior accounted for between 22% and 60% of the variance in prediction of temperament scores. In general, more active fetuses were more difficult, unpredictable, unadaptable, and active infants. Higher fetal heart rate was associated with lower emotional tone, activity level, and predictability. We conclude that features of fetal neurobehavior provide the basis for individual differences in reactivity and regulation in infancy.

Adult↗
PubMed1995

Transcriptional up-regulation of the mouse gene for the muscle-specific subunit of enolase during terminal differentiation of myogenic cells.

The glycolytic enzyme enolase (EC 4.2.1.11) exists as dimers formed from three structurally related subunits alpha, beta, and gamma, encoded by separate genes. The gene encoding the beta-subunit is expressed only in striated muscles. We have previously shown that the beta-enolase gene belongs to a small subset of muscle-specific genes showing transcriptional activity in cultured myoblasts, prior to withdrawal from the cell cycle. An increase in the level of beta-enolase mRNA occurs during terminal differentiation of myoblasts. To investigate the mechanisms underlying this increase, we have simultaneously estimated, under steady state conditions, the rate of synthesis and the stability of beta-enolase mRNA in proliferating C2.7 myoblasts as well as in differentiating myotubes. The method used is based on the isolation of newly synthesized RNA from the total RNA pool, following pulse-labeling of intact cells in the presence of 4-thiouridine. The results described here demonstrate a coordinate increase in newly synthesized and total beta-enolase mRNA, while the mRNA half-life, about 4 hr, remains unchanged in the course of terminal differentiation. The expression of the gene for insulin-like growth factor-II (IGF-II), a major positive regulator of myogenesis, was analyzed using the same approach. It is concluded that the up-regulation of beta-enolase as well as IGF-II gene expression in differentiating muscle cells reflects an increased rate of entry of newly synthesized mRNAs into the general pool of transcripts without changes in their respective half-lives.

Animals↗
PubMed1995

The association between occupational factors and preterm birth: a United States nurses' study. Research Committee of the Association of Women's Health, Obstetric, and Neonatal Nurses.

OBJECTIVE: Our purpose was to evaluate factors associated with preterm birth among a national sample of U.S. nurses. STUDY DESIGN: We conducted a case-control study of 210 nurses whose infants were delivered prematurely (< 37 weeks) (cases) and 1260 nurses whose infants were delivered at term (> or = 37 weeks) (controls). An occupational fatigue score was constructed from four sources and varied from 0 to 4. The relation between occupational activity (including hours working and fatigue score) and preterm birth was analyzed with the use of Pearson chi 2 tests, estimates of odds ratios with 95% confidence intervals, and multivariate logistic regression; we controlled for confounding factors. RESULTS: Factors significantly associated with preterm birth included hours worked per week (p < 0.002), per shift (p < 0.001), and while standing (p < 0.001); noise (p = 0.005); physical exertion (p = 0.01); and occupational fatigue score (p < 0.002). The adjusted odds ratios were 1.6 (p = 0.006) for hours worked per week (< or = 36 vs > 36) and 1.4 (p = 0.02) for fatigue score < 3 vs > or = 3. CONCLUSIONS: Preterm birth among working women may be related to hours worked per day or week and to adverse working conditions.

Case-Control Studies↗
PubMed1995

One framework, two systems: flexible abductive methods in the problem-space paradigm applied to antibody identification and biopsy interpretation.

Our goal is to build flexible knowledge-based systems which can use a variety of problem-solving methods and additional task knowledge, without altering the method or task representation. For this purpose, we use a problem-space architecture which allows opportunistic adaptation of problem-solving methods based on the particular goal, situation and knowledge available. Within this framework, we have developed an opportunistic problem-solving method for flexible abductive problem solving. The basic method was specified in terms of potential subgoals and preferences regarding the order of subgoals. This technique avoids specification of any unnecessary procedural commitments, making the resulting method very general and robust. We then developed two systems using this basic abductive method with additional domain-dependent search-control and task knowledge. The additional knowledge alters/overrides some of the minimal knowledge provided by the basic method. Behavior of these systems can change quite dramatically depending on the added increments of knowledge. Knowledge available at runtime shapes the method and hence the behavior. Moreover, even in the absence of strong domain knowledge, due to the wide coverage of the basic abductive method and the general architecture it is based on, the systems are always able to perform some problem solving--they are not brittle. The specific systems implemented are RedSoar and LiverSoar in the domain of red blood cell antibody identification and liver biopsy interpretation, respectively. We discuss the designs, implementations and evaluations of these systems, emphasizing the role the flexible abductive problem-solving method plays.

Antibodies↗
PubMed1995

Plasma thrombomodulin levels in women with systemic lupus erythematosus.

Thrombomodulin (TM), an endothelial cell membrane glycoprotein, is released into blood as a soluble TM antigen after inflammation or injury to endothelium. Systemic lupus erythematosus (SLE) is characterized by multisystem inflammation of vascular endothelium. The objective of this study is to determine the circulating TM levels in pregnant and nonpregnant SLE women and the correlation of plasma TM levels with variables used to assess SLE activity. We found that there were no significant differences in plasma TM levels among pregnant SLE, nonpregnant SLE, and normal pregnant patients. However, significantly higher plasma TM levels were found in some SLE women with active disease or preeclampsia.

Biomarkers↗
PubMed1995

Does preeclamptic pregnancy increase fetal-maternal hemorrhage?

Since pathologic changes of the placenta have been found in preeclamptic pregnancies, a relationship between fetal-maternal hemorrhage and preeclampsia was investigated. Sixty-two women with singleton pregnancies in the third trimester were studied. Thirty-one of these women with preeclampsia were matched with 31 normotensive healthy pregnant women. Maternal serum levels of alpha-fetoprotein (MSAFP) and Kleihauer-Betke (KB) test were determined to reflect the degree of fetal-maternal hemorrhage. There were no significant differences in MSAFP levels, MSAFP to creatinine ratio, or the appearance of fetal cells as measured by the KB test between preeclamptic pregnancies and matched controls. Our data do not suggest that fetal-maternal hemorrhage is increased in pregnant women with preeclampsia.

Adult↗
PubMed1994

Gene therapy of murine teratocarcinoma: separate functions for insulin-like growth factors I and II in immunogenicity and differentiation.

Teratocarcinoma is a germ-line carcinoma giving rise to an embryoid tumor with structures derived from the three embryonic layers: mesoderm, endoderm, and ectoderm. Teratocarcinoma is widely used as an in vitro model system to study regulation of cell determination and differentiation during mammalian embryogenesis. Murine embryonic carcinoma (EC) PCC3 cells express insulin-like growth factor I(IGF-I) and its receptor, while all derivative tumor structures express IGF-I and IGF-II and their receptors. Therefore the system lends itself to dissect the role of these two growth factors during EC differentiation. With an episomal antisense strategy, we define a role for IGF-I in tumorigenicity and evasion of immune surveillance. Antisense IGF-I EC transfectants are shown to elicit a curative anti-tumor immune response with tumor regression at distal sites. In contrast, IGF-II is shown to drive determination and differentiation in EC cells. Since IGF-I and IGF-II bind to type I receptor and antisense sequence used for IGF-II cannot form duplex with endogenous IGF-I transcripts, it follows that this receptor is not involved in determination and differentiation.

Animals↗
PubMed1994

Expression of insulin-like growth factors I and II in conceptuses from normal and diabetic mice.

Insulin-like growth factors (IGF-I and IGF-II) play an important regulatory role in fetal growth and development. Alterations in expression of these growth factors may result in developmental abnormalities, macrosomia, and intrauterine growth retardation, which occur with a higher incidence in diabetic pregnancies. In situ hybridization histochemistry was employed to investigate the distribution and abundance of IGF-I and IGF-II in peri-implantation and postimplantation conceptuses from normal and streptozotocin-treated diabetic mice. Animals were sacrificed on gestational days 5, 6, 7, 8, and 9. The entire uterine horn was prepared for hybridization with antisense and sense alpha 35S-dATP labeled oligonucleotide probes for IGF-I, IGF-II, and mouse beta-actin. IGF-I transcript was apparent only in myometrium at 6 days of gestation in normal and diabetic mice. IGF-II transcripts were restricted to trophoectoderm cells within the implantation chamber on day 5. Following implantation, IGF-II transcripts were found in trophoectodermal derivatives, primitive endoderm, mesoderm, heart, walls of the foregut, and mesenchyme in normal and diabetic postimplantation conceptuses. There were no apparent differences between normal and diabetic samples in the distribution and abundance of the IGF-II transcript from gestational days 7, 8, and 9. The embryos from the diabetic mother at day 6 were growth retarded and had a significant decrease in the expression of IGF-II. These results suggest that maternal hyperglycemia may retard development of the early implanting conceptus in a narrow window around day 6 through a mechanism involving decreased IGF-II expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Elevated urine thrombomodulin/creatinine ratio in severely preeclamptic pregnancies.

A relationship between the urine thrombomodulin/creatinine ratio and preeclampsia was investigated. Preeclamptic women had a higher urine thrombomodulin/creatinine ratio than did matched controls. However, significantly elevated urine thrombomodulin/creatinine ratios were found in severely, but not mildly, preeclamptic pregnancies.

Adult↗
PubMed1994

Elevated serum human chorionic gonadotropin as evidence of secretory response in severe preeclampsia.

OBJECTIVE: Because preeclampsia is a trophoblastic disorder and human chorionic gonadotropin is secreted from trophoblast, we sought to determine whether measurement of serum human chorionic gonadotropin might reflect a different trophoblastic secretory response of preeclampsia. STUDY DESIGN: Twenty patients with mild preeclampsia and 12 with severe preeclampsia were matched with 32 healthy, normotensive women in the third trimester with singleton pregnancies. Serum total human chorionic gonadotropin and total human chorionic gonadotropin-beta were measured by a two-site immunoenzymometric assay, and total hCG-alpha was determined by a double-antibody radioimmunoassay. Wilcoxon signed-rank and Mann-Whitney rank-sum tests were used for statistical analysis. RESULTS: Serum total human chorionic gonadotropin, total human chorionic gonadotropin-alpha, and total human chorionic gonadotropin-beta levels were significantly higher in severely preeclamptic women (p < 0.05), but not in those with mild preeclampsia, compared with those in their matched controls. CONCLUSION: Elevated serum human chorionic gonadotropin levels in severely preeclamptic women might reflect a significantly pathologic change and secretory reaction of the placenta.

Adult↗
PubMed1994

Interpretation of biophysical profiles by nurses and physicians.

OBJECTIVE: To determine the agreement between nurse and physician interpretation of biophysical profile scores. DESIGN: A prospective evaluation of videotaped biophysical profiles was independently scored by four nurse and four physician interpreters and compared to that of an expert physician. SETTING: The fetal assessment center of a large tertiary-care center; study included women from public and private practices. PATIENTS: Twenty-three women with high-risk pregnancies who were regularly scheduled for a biophysical profile. Women pregnant with multiple fetuses or whose fetuses were less than 28 weeks' gestational age or had severe fetal anomalies were excluded. MAIN OUTCOME MEASURE: The proportion of agreement between the physicians and nurses and the physician expert was calculated for each biophysical profile criterion. RESULTS: The kappa statistic was used to evaluate the proportion of agreement with the "gold standard." When compared with the expert, physicians showed 60% moderate or substantial agreement, and the nurses showed 80% moderate or substantial agreement. CONCLUSIONS: Nurses' interpretations of biophysical profiles were at least as reliable as physicians' when compared with an expert reviewer.

Adolescent↗
PubMed1994

Flows of nitrogen and amino acids in dairy cows fed diets containing supplemental feather meal and blood meal.

Four Holstein cows, fitted with ruminal and duodenal cannulas, were used to determine the effects of supplemental feather meal and blood meal on ruminal fermentation and flows of N and AA to the duodenum. The basal diet contained (DM basis) 9.9% chopped alfalfa hay, 39.7% corn silage, 34.7% cracked corn, 8.2% corn starch, 2.1% vitamins and minerals, 4.4% casein, and 1% urea. A combination of feather meal and blood meal (3:1 on an N basis) was used to replace 0, 33, 67, and 100% of the casein and urea in the basal diet in a Latin square design. Intakes of DM, OM, and N were similar for all diets. Flows of total N, NAN, individual AA, total AA, and total essential AA were unaltered as supplemental feather meal plus blood meal increased. Flows of microbial N tended to decrease, but flow of non-ammonia, nonmicrobial N increased as supplemental feather meal plus blood meal increased. Increased proportions of dietary feather plus blood meal decreased the proportions of Ile, Lys, Met, and Thr in duodenal digesta. Molar percentages of ruminal pH and VFA were unchanged, but concentrations of ruminal NH3 N decreased linearly as supplemental feather meal plus blood meal increased. For the diets fed in this study, inclusion of one-third of the supplemental protein from feather plus blood meal resulted in maximum flows of NAN and microbial N to the small intestine.

Amino Acids↗
PubMed1994

Addition of ruminally degradable crude protein and branched-chain volatile fatty acids to diets containing hydrolyzed feather meal and blood meal for lactating cows.

This study investigated the effects of amounts of RDP and branched-chain VFA on milk production and DMI by 32 early lactation Holstein cows fed diets based on corn silage and corn. All supplemental dietary protein was supplied by animal protein by-products and urea. Hydrolyzed feather meal and ring-dried blood meal served as sources of supplemental protein and were fed in a 3:1 ratio on a N basis. The experimental design was a completely randomized design with a 2 x 2 factorial arrangement of treatments. Main factors were percentage of RDP (8.0 vs. 9.5% of dietary DM) and amount of branched-chain VFA in the diet (0 vs. 90 g/d per cow). Urea was used to adjust the amount of degradable CP. Individual DMI, milk production, and milk composition were monitored during wk 5 to 19 of lactation. Ruminal fluid and blood were collected to examine the treatment effects on ruminal VFA patterns and plasma urea N concentrations. The DMI, total milk production, and milk component yield were unaffected by treatments. The molar percentages of isobutryate, isovalerate, and n-valerate increased when branched-chain VFA were fed, and concentrations of urea N in plasma increased with higher percentages of RDP. A combination of feather meal and blood meal can be used as supplemental protein to support high milk production (> 37 kg/d) in early lactation. No production benefits were observed by increased dietary RDP or branched-chain VFA.

Animal Feed↗