Priming with secreted glycoprotein G of respiratory syncytial virus (RSV) augments interleukin-5 production and tissue eosinophilia after RSV challenge

The respiratory syncytial virus (RSV) G glycoprotein promotes differentiation of type 2 CD4+ T lymphocytes and induces an eosinophilic response in lungs of RSV-infected mice. A unique feature of G is that a second initiation codon in the transmembrane region of the glycoprotein results in secretion of soluble protein from infected cells. Recombinant vaccinia viruses that express wild-type G (vvWT G), only secreted G (vvM48), or only membrane-anchored G (vvM48I) were used to define the influence of G priming on immunopathogenesis. Mice immunized with vvM48 had more severe illness following RSV challenge than did mice primed with vvWT G or vvM48I. Coadministration of purified G during priming with the construct expressing membrane-anchored G shifted immune responses following RSV challenge to a more Th2-like response. This was characterized by increased interleukin-5 in lung supernatants and an increase in G-specific immunoglobulin G1 antibodies. Eosinophils were present in the infiltrate of all mice primed with G-containing vectors but were greatest in mice primed with regimens including secreted G. These data suggest the form of G protein available for initial antigen processing and presentation is an important factor in promoting Th2-like immune responses, including the induction of lung eosinophilia. The ability of RSV to secrete G protein may therefore represent a viral strategy for immunomodulation and be a key determinant of disease pathogenesis.

Effects of dietary supplementation on nutrient digestion and the milk yield of intensively grazed lactating dairy cows

Fourteen midlactation Holstein cows were used in an 80-d study to examine supplementation strategies during intensive rotational grazing. Factors examined were the concentration of protein in the supplement [12 or 16% crude protein (CP) on a dry matter basis] and the amount of supplement offered (6.4 or 9.6 kg/d per cow). The supplement was offered in equal portions three times daily after milking. Pasture, composed of alfalfa (Medicago sativa) and orchardgrass (Dactylis glomerata), was divided into 27 0.16-ha paddocks that were grazed for 12 to 24 h. Intake of forage tended to increase as CP in the supplement increased but was unaffected by the amount of supplement offered. Intakes of organic matter and dry matter and the digestion of these nutrients in the total tract increased as CP in the supplement increased and as the amount of supplement increased. Ruminal pH and concentrations of volatile fatty acids were unaffected by treatments, but concentrations of NH3 N increased as CP in the supplement increased. An increase in CP resulted in a greater intake and flow of total N to the duodenum. The flow of microbial N to the duodenum and the efficiency of microbial protein synthesis were unaffected by treatment. Flows of total amino acids and essential amino acids to the duodenum tended to increase as CP in the supplement increased. Yield of fat-corrected milk and concentrations of fat and protein in milk were unaffected by treatment. These results suggested that the supply and digestion of nutrients in grazing dairy cows may be improved through an increase in the CP concentration of the supplement or the amount of supplement offered. However, effects on the yield of milk and milk components may be small.

Overexpression of interleukin-4 delays virus clearance in mice infected with respiratory syncytial virus

Although interleukin-4 (IL-4) expression has been implicated in vaccine-enhanced respiratory syncytial virus (RSV) disease, its role in mediating the immune response to primary RSV infection remains unclear. To assess the effect of IL-4 production on typical RSV infection, transgenic mice which either overexpress or fail to express IL-4 were challenged intranasally with RSV and their responses were compared to those of the parent strains. IL-4-deficient mice eliminated virus from the lung as quickly as did C57BL/6 controls. In contrast, mice which constitutively overexpress IL-4 showed delayed virus clearance compared with mice of the FVB/N control strain, although peak viral titers did not differ. IL-4 overexpression increased the magnitude of the subsequent antibody response. Lung lymphocytes harvested from IL-4-overexpressing mice post-RSV challenge showed diminished RSV-specific cytolytic activity compared with controls. Both IL-4-deficient and IL-4-overexpressing strains resisted rechallenge. These data imply that constitutive IL-4 expression delays or suppresses the development of a virus-specific cytotoxic lymphocyte population important in clearing primary RSV infection.

Suppression of insulin-like growth factor type I receptor by a triple-helix strategy inhibits IGF-I transcription and tumorigenic potential of rat C6 glioblastoma cells

Homopurine (AG) and homopyrimidine (CT) oligodeoxyribonucleotides predicted to form triple-helical (triplex) structures have been shown to specifically suppress gene expression when supplied to cultured cells. Here we present evidence that homopurine RNA (effector) sequences designed to form a triplex with a homopurine. homopyrimidine sequence 3' to the termination codon of the insulin-like growth factor type I receptor (IGF-IR) structural gene can efficiently suppress IGF-IR gene transcription. Transfection vectors were constructed to drive transcription of either AG or CT variant triplex-forming strands. To increase the probability of obtaining stable transfectants with adequate expression of effector sequences, these were designed to be transcribed together with cDNA sequences conferring neomycin resistance as a fusion transcript. Rat C6 glioblastoma cells transfected with the AG variant showed dramatic reduction of IGF-IR transcripts compared with untransfected cells. The AG transfectants also exhibited marked down-regulation of the IGF-I, and an enhanced accumulation of serine protease inhibitor nexin-I mRNA. Similar changes in gene expression were observed following transfection of C6 cells with constructs transcribing antisense RNA to IGF-IR transcripts, but were not observed in C6 cells transfected with either the CT triplex variant or with vector lacking triplex-forming sequences. Moreover, C6 cells transfected with AG triplex variant displayed a dramatic inhibition of tumor growth when injected into nude mice. The results suggest that a triple-helix strategy can be used to inhibit transcription elongation of the IGF-IR gene, and emphasize the efficacy of triplex-mediated gene inhibition in an animal model.

Increase in ambient temperature may explain decrease in amniotic fluid index

In the third trimester, the amniotic fluid index (AFI) may be affected by maternal fluid status. As the ambient temperature increases, there is an increase in insensible fluid loss and the potential for dehydration. We hypothesize that as temperature increases there would be a concomitant decrease in AFI. From June 11 to August 16, 1993, during a period of unusual high heat, 42 women with singleton pregnancies between 27 and 40 weeks' gestation undergoing serial antenatal testing had AFI determinations recorded at least weekly. The daily high ambient temperature in our urban area was subsequently obtained. A 2-, 3-, and 4-day mean temperature prior to the test date was compared to AFI using a Spearman-rank Correlation. The daily high temperature ranged from 71 to 104 degrees F and AFI values ranged from 1.7 to 24.7 cm during the study period. There was a significant correlation between the 2-, 3-, and 4-day mean temperature and AFI, with the 4-day mean being the most significant (r = 0.31, p < 0.001). Fluctuations in ambient temperature are inversely correlated to changes in AFI. This relationship should be taken into account when interpreting the AFI as a measure of fetal well-being.

Complementary and non-coincident increases in heart rate variability and irregularity during fetal development

1. Two distinct notions of variability have been defined to assess heart rate: deviation from a constant output (SD) and irregularity. One statistical measure of irregularity is approximate entropy, with greater irregularity corresponding to larger approximate entropy values. The specific aims of this investigation were to determine the manner in which SD and irregularity evolve during fetal development and whether this evolution is coincident or distinct. 2. Fetal heart rate was computed in 14 males and 17 females for 15 min of undisturbed recording using a fetal actocardiograph at 4 week intervals from 20 to 36 weeks gestation. 3. Mean heart rate decreased significantly with gestational ages (P < 0.05). SD increased significantly from 4.4 +/- 0.3 ms (SEM) at 20 weeks to 7.7 +/- 0.4 ms at 36 weeks (P < 0.05) and was similar between male and female fetuses (P = 0.57). Fixed approximate entropy increased significantly from 0.47 +/- 0.04 to 0.78 +/- 0.03, paralleling the change in SD (P < 0.01). Notably, normalized approximate entropy, which decorrelates SD from regularity, increased significantly with gestational age (P < 0.01) for males, while it remained relatively constant for females (P = 0.68). Approximate entropy was significantly lower at 20 weeks in males than females (P < 0.05); however, the values were similar by 28 weeks gestation. 4. Our results demonstrate that variability increases, and that irregularity increases, independently in male fetuses but not female fetuses, consistent with an increase in the coupling of emerging networks with gestational age. The present study demonstrates the complementary information obtained by analyses of both measures of variability and regularity. This reinforces a difference in gender-based development as noted in the separate context of fetal lung maturation.

Potential triple helix-mediated inhibition of IGF-I gene expression significantly reduces tumorigenicity of glioblastoma in an animal model

Oligonucleotide-directed triple helix formation is a powerful approach to block transcription of specific genes. Although the oligonucleotide triplex approach is efficient for inhibiting gene expression in cultured cells, suppression is transient. We developed an approach which inhibits insulin-like growth factor-I (IGF-I) expression following stable transfection of C6 rat glioblastoma cells with a plasmid from which an RNA is transcribed that codes for the third strand of a potential triple helix. We tested the ability of this expression vector to inhibit IGF-I gene expression in vitro as well as tumorigenesis in an animal. A dramatic reduction of IGF-I RNA and protein levels in cultured cells occurred following transfection of rat C6 cells with a eukaryotic expression plasmid encoding the oligopurine variant of the triple helix but not the oligopyrimidine or a control sequence. The cells transfected with the oligopurine variant displayed morphological changes, upregulation of major histocompatibility complex I, and increased expression of protease nexin I. Dramatic inhibition of tumor growth occurred in nude mice following injection of transfected C6 cells. To our knowledge, this is the first example of tumor growth inhibition in an animal model employing a triple helix approach.

Eight-week toxicity study of 60 Hz magnetic fields in F344 rats and B6C3F1 mice

Toxicity studies were performed by exposing F344/N rats and B6C3F1 mice (10 animals per sex per species per group) to transient-free, linearly polarized 60 Hz magnetic fields for 8 weeks. Targeted magnetic fields strengths used were 0 gauss (G; sham control fields did not exceed 0.001 G), 0.02 G, 2 G, and 10 G. Exposure was whole-body and continuous for 18.5 hr per day, 7 days per week. An additional group of rats and mice was exposed intermittently (1 hr on/1 hr off) to 10 G fields for the same period of time. Endpoints evaluated included morbidity, mortality, gross pathology, histopathology, body/organ weights, clinical chemistry (rats only), and hematology (rats only). All mice and all male rats survived until the end of the study. One female rat (2-G exposure group) died during Week 7 of the study; the death was not attributed to magnetic field exposure. In both studies, the mean body weight gains of exposed animals were similar to those of the respective controls. There were no gross, histological, hematological, or biochemical lesions attributed to magnetic field exposure. Statistically significant increases in liver weight and liver to body weight ratio occurred in female rats of all exposure groups but only at the termination. These data suggest that, for the variables evaluated in these studies, an 8-week exposure to linear-polarized, transient-free 60 Hz magnetic fields at field intensities of up to 10 G is not associated with significant toxicity in F344/N rats and B6C3F1 mice. Furthermore, there was no toxicity observed in animals receiving intermittent (1 hr on/1 hr off) exposures to 10-G fields. A 2-year study in F344/N rats and B6C3F1 mice is nearing completion of the in-life phase without overt toxicity in any exposed group. It is premature, however, to make any prediction concerning the possible influence of exposure to 60 Hz magnetic fields on cancer rates.

Changes in immunologic cell surface markers during cocaine withdrawal in pregnant women

To evaluate the effects of acute cocaine withdrawal on the immune system of pregnant women, we analyzed changes in a panel of cell surface markers and plasma proteins that have immunological importance. The cell surface markers included complement receptors [CR1 (CD35), CR2 (CD21), CR3 (CD11b, CD18)], immunoglobulin Fc receptors [FcgammaRII (CD32), FcgammaRIII (CD16)], proteins important for lymphocyte function [CD3, CD4, CD8, CD19, CD25, CD45RA], and the framework antigen HLA-ABC. We also measured levels of the plasma proteins C3, C4, IgG, IgM, and IgA, along with the cytokine interleukin-2, soluble lymphocyte markers sCD25, sCD4, sCD8, IL-2, and soluble immune complexes. While no significant changes were seen in the levels of plasma proteins, changes paralleling the course of acute withdrawal were seen in complement receptors and immunoglobulin Fc receptors on leukocyte subpopulations. By contrast, proteins important for lymphocyte function were relatively unperturbed. There was an increase in receptor expression at the onset of withdrawal that peaked 3-5 days after last cocaine use, followed by a decrease in expression to initial (pre-withdrawal) levels. These changes in cell surface receptors may reflect altered immune function in the women who were withdrawing from cocaine.

Immune function and host defense in rodents exposed to 60-Hz magnetic fields

This study was conducted to evaluate the influence of subchronic exposure to pure, linearly polarized 60-Hz magnetic fields (MF) on the host immune response in mice. The experimental design was as follows: three groups were exposed continuously (18.5 hr/day) to MF at field strengths of 0.02, 2, or 10 gauss (G), one group was exposed intermittently (1 hr on/1 hr off) to MF at a field strength of 10 G, and one group served as a sham control. Experimental endpoints included spleen and thymus weights and cellularity, antibody-forming cell (AFC) response, delayed-type hypersensitivity (DTH) response, splenic lymphocyte subset analysis, susceptibility to infection with Listeria monocytogenes, and natural killer (NK) cell activity. No differences in body weight, lymphoid organ weight, or lymphoid organ cellularity were observed in any MF-exposed group in comparison to sham controls. Likewise, no statistically significant differences were found in comparisons of AFC responses. Isolated statistically significant differences from control were observed in MF-exposed mice in the DTH assay, although no clear dose-related pattern of altered activity was seen. Splenic lymphocyte subset parameters examined were within normal limits in all groups, and no differences between control and MF-exposed mice were found. Host resistance to bacterial infection was not altered at any MF exposure examined in this study. Finally, although apparently dose-related, statistically significant alterations were observed in an initial study of NK cell function, repeat studies failed to demonstrate a consistent pattern of alteration.

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.

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.

T-cell lymphocytic lymphoma involving the prostate presenting as elevated PSA in paraplegia: case report

The vast majority of cancers that involve the prostate are adenocarcinomas of the duct-acinar secretory epithelium. Other cancers, primarily leukemia and lymphoma, can involve the prostate and lead to an abnormal digital examination or elevated serum prostate specific antigen (PSA). The case discussed is that of a 62 year-old male with T12 complete paraplegia who presented with a persistently elevated PSA and was subsequently diagnosed with T-cell lymphoma involving the prostate. Although rare, leukemia and lymphoma involving the prostate should be included in the differential diagnosis of patients being evaluated for adenocarcinoma of the prostate.

Developmental toxicity study of 60 Hz (power frequency) magnetic fields in rats

Considerable public concern has developed regarding possible adverse reproductive outcomes resulting from exposure to power frequency magnetic fields (MF). To identify possible effects of MF exposure on fetal development, timed-pregnant female Sprague-Dawley rats (55/ group) received continuous exposure to linearly polarized, transient-free 60 Hz MF at field strengths of 0 Gauss (G; sham control), 0.02 G, 2 G, or 10 G, or intermittent (1 hr on/1 hr off) exposure to 10 G fields. Dams received MF or sham exposures for 18.5 hr/day on gestation days 6 through 19. A positive control group of 15 dams received daily oral doses of 85 mg ethylenethiourea (ETU)/kg body weight on gestation days 11, 12, and 13; positive control dams received no MF exposure. Ambient and experimentally generated MF were monitored continuously throughout the study. Experimentally generated MF were within 2% of the target field strengths at all times, and ambient MF to which sham controls were exposed did not exceed 0.7 mG at any point in the study. No evidence of maternal toxicity was identified in any MF-exposed dam; mean maternal body weight and organ weights in groups exposed to MF did not differ from those in sham controls. Comparisons of fetal viability and body weight demonstrated no biologically significant differences between MF-exposed groups and sham controls. Similarly, a battery of gross external, visceral, skeletal, and cephalic examinations demonstrated no significant differences in the incidence of fetal malformations or anomalies in MF-exposed groups vs. sham controls. By contrast, 100% of the fetuses in the positive control group treated with ETU demonstrated malformations and reduced body weight. Exposure of pregnant Sprague-Dawley rats to 60 Hz at field strengths up to 10 G during gestation days 6-19 did not produce biologically significant effects in either dams or fetuses. These results do not support the hypothesis that exposure to pure, linearly polarized 60 Hz MF is a significant risk factor for the developing fetus.

Structure and chromosomal localization of the human homeobox gene Prox 1

The genomic organization and nucleotide sequence of the human homeobox gene Prox 1 as well as its chromosomal localization have been determined. This gene spans more than 40 kb, consists of at least 5 exons, and encodes an 83-kDa protein. It shows 89% identity with the chicken sequence at the nucleotide level in the coding region, while the human and chicken proteins are 94% identical. Among the embryonic tissues analyzed (lens, brain, lung, liver, and kidney), the human Prox 1 gene is most actively expressed in the developing lens, similar to the expression pattern of the chicken Prox 1 gene. The Prox 1 gene was mapped to human chromosome 1q32.2-q32.3.

Influence of source and amount of dietary protein on milk yield by cows in early lactation

The purpose of this research was to examine the effects of various amounts of CP and RUP on AA flow to the small intestine and milk yield of lactating dairy cows. The first trial was a 5 x 5 Latin square design using five ruminally and duodenally cannulated multiparous cows. Diets contained chopped alfalfa hay, corn silage, high moisture corn, solvent-extracted soybean meal, and specially processed soybean meal (60.2% RUP). Soybean meal replaced high moisture corn to increase dietary CP from 14.5 to 16.5 or 18.5%, and specially processed soybean meal replaced solvent-extracted soybean meal in diets containing 16.5 or 18.5% CP to provide 6.2, 7.3, 6.7, and 8.3% RUP. Increasing dietary CP increased the flows of all AA to the duodenum. Increasing dietary RUP increased flows of Arg, His, Lys, Phe, Asp, and Glu to the duodenum. In a second trial, 36 cows were fed diets similar to those used in trial 1. Increased amounts of RUP in diets tended to increase milk yield because of improved protein status, improved intake of metabolizable energy, or both.

Development of fetal movement--fetal heart rate coupling from 20 weeks through term

This study documents the development of fetal heart rate (FHR) change in response to fetal movement (FM) in healthy fetuses from 20 weeks' gestational age through term. Thirty-one fetuses received 50 min of Doppler-based monitoring at 20, 24, 28, 32, 36 and 38-39 weeks. FHR and FM were continuously digitized. A coupling index was computed as the percentage of FMs associated with increases in FHR of 5 beats/min or more within -5 or +15 s of movement onset. The latency between FM onset and FHR change was also computed, as were the amplitude and duration of all movements. FM and FHR became more integrated with advancing gestation. Coupling increased and the latency between FM and FHR changes decreased. Maternal age, blood pressure and fetal sex did not affect FM-FHR coupling, but fetuses of women who reported greater stress in their daily lives and had faster heart rates displayed reduced coupling. These data suggest that the development of FM-FHR coupling reflects the development of the central nervous system during gestation, and that development may be affected by maternal factors.

Surgery for pancreatic tumors during pregnancy: a case report and review of the literature

Seven cases of surgery of pancreatic tumors during pregnancy have been reported in the literature. Six of the cases resulted in live term births. The patient discussed herein, a 37-year-old para 2-0-0-2 white female, had surgery for the removal of a pancreatic mass at 20 2/7 weeks' gestation. No intraoperative complications occurred, and both mother and fetus appeared to have done well. The postoperative course was complicated by pseudomembranous enterocolitis caused by C. difficile, which was treated with antibiotics. Despite treatment, diarrhea continued, and the patient was readmitted to the hospital for hydration and further antibiotics at 27 weeks. Three days after admission, the fetus was noted to have poor biophysical testing and a caesarean delivery was performed. The infant was found to have a large intracerebral hemorrhage, which most likely occurred antenatally, and life support was discontinued shortly after birth. We conclude from this that surgery for a pancreatic mass in pregnancy should be approached cautiously, and the risk to both the mother and fetus should be considered.

Recent advances in the estimation of population exposure to mobile source pollutants

The U.S. Environmental Protection Agency (EPA) has developed several computer-based exposure models applicable to pollutants which are directly or indirectly linked to mobile sources. Probabilistic versions of the National Ambient Air Quality Standards (NAAQS) Exposure Model (pNEM) have been used to estimate the exposures of urban populations to carbon monoxide and ozone. An enhanced version of the Hazardous Air Pollutant Exposure Model (HAPEM-MS) has been used to develop city-specific estimates of exposure to benzene and other volatile organic compounds emitted by mobile sources. These models are similar in that each contains algorithms that simulate microenvironmental pollutant levels, time/activity patterns, and commuting patterns. The pNEM models also provide estimates of equivalent ventilation rate (EVR), defined as ventilation rate divided by body surface area. This paper summarizes the methods and results of selected research projects conducted since 1991 with the goal of improving pNEM, HAPEM-MS, and similar exposure models applicable to mobile source pollutants. The studies include: (1) the development of an improved algorithm for estimating EVR, (2) a field study to measure ozone levels near roadways and inside vehicles, (3) the development of an algorithm for estimating school commuting patterns, and (4) the construction of a comprehensive database containing time/activity data from ten activity diary studies.

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.

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.

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.

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.