Search PubMed⌕ Search

Biomedical subjects

R L Fischer

Publications and source records attributed to R L Fischer.

At least 55 records · Page 3Linked to original sources
PubMed1993

Amniotic fluid volume estimation in the postdate pregnancy: a comparison of techniques.

OBJECTIVE: To determine the amniotic fluid (AF) volume estimation technique with the greatest diagnostic value with respect to perinatal outcome in the postdate pregnancy. METHODS: One hundred ninety-eight women who were at least 40 weeks' gestation based on ultrasound confirmation or establishment of dates were evaluated twice weekly with nonstress tests (NSTs) and AF volume estimation. Various indices of AF volume were measured and correlated with perinatal outcome. Receiver operating characteristic curves were used to determine optimal cutoff values. RESULTS: There was a significantly larger maximal vertical pocket in those pregnancies with a normal perinatal outcome than in those with abnormal outcome (4.2 +/- 1.4 versus 3.2 +/- 2.0 cm; P = .02). A statistically significant difference was also seen with the AF index (10.0 +/- 4.5 versus 7.5 +/- 5.0 cm; P = .01). Analysis revealed that the optimal cutoff for identifying clinically significant oligohydramnios was a largest vertical pocket less than 2.7 cm, with an adjusted odds ratio for abnormal perinatal outcome of 7.11 (95% confidence interval [CI] 2.79-18.16). Its sensitivity of 50.0% and specificity of 87.9% were superior to the diagnostic value of the AF index of 5 cm, which had a sensitivity of 29.2% and specificity of 89.1%. CONCLUSION: A largest vertical pocket threshold of 2.7 cm had the greatest diagnostic value for identifying the postdate pregnancy at risk for abnormal perinatal outcome, surpassing the AF index and the 2-cm largest vertical pocket rule.

Adult↗
PubMed1992

Self-reported depression and negative pregnancy outcomes.

Studies addressing the association of depressive symptoms late in pregnancy with pregnancy outcome are lacking. We administered the revised Beck Depression Inventory (BDI) in the third trimester to 323 inner-city adolescents and 389 adults, who were mostly from U.S. minority groups (28.7% Puerto Rican, 61.8% black, 9.6% white). The BDI total score was regressed (as a continuous variable) on indicators of poor pregnancy outcome. There was no relationship of BDI scores with pregnancy outcome in the adolescents. However, among the adult gravidas the risk of a poor outcome rose 5-7% (p < 0.05) for each point the BDI total score increased. For the adults, at a cut-off score of 21 for the BDI, suggestive of clinical depression, the risk of delivering a low birth weight infant of < 2500 g was 3.97 (95% confidence interval [CI] 3.80-4.15); the risk for having a preterm delivery at < 37 completed weeks' gestation was 3.39 (95% CI 3.24-3.56); and their risk of having a small-for-gestational-age infant at < 10th percentile for standards was 3.02 (95% CI 2.88-3.17). Future research should address the physiological mechanisms associated with symptoms of depression that might contribute to an increased risk of poor outcomes and extend the findings to gravidas from different socioeconomic strata.

Adolescent↗
PubMed1992

Anemia vs iron deficiency: increased risk of preterm delivery in a prospective study.

Using criteria from the Centers for Disease Control, anemia and iron-deficiency anemia (anemia with serum ferritin concentrations less than 12 micrograms/L) were assessed in greater than 800 inner-city gravidas at entry to prenatal care. Iron-deficiency anemia was associated with significantly lower energy and iron intakes early in pregnancy and a lower mean corpuscular volume. The odds of low birth weight were tripled and of preterm delivery more than doubled with iron deficiency, but were not increased with anemia from other causes. When vaginal bleeding at or before entry to care accompanied anemia, the odds of a preterm delivery were increased fivefold for iron-deficiency anemia and doubled for other anemias. Inadequate pregnancy weight gain was more prevalent among those with iron-deficiency anemia and in those with anemias of other etiologies. The prevalence of iron-deficiency anemia (3.5%), however, was lower than anticipated for an inner-city, minority population in whom most anemias had been attributed clinically to iron deficiency.

Adolescent↗
PubMed1992

Organization of Ripening and Ethylene Regulatory Regions in a Fruit-Specific Promoter from Tomato (Lycopersicon esculentum).

Tomato (Lycopersicon esculentum) fruit ripening is initiated by an increase in ethylene hormone concentration. E8 gene transcription is fruit-specific and is activated at the onset of ripening and in unripe fruit treated with exogenous ethylene. To understand how E8 gene transcription is controlled during ripening, we analyzed the effect of deletions of flanking DNA sequences on E8 gene expression in transgenic tomato fruit. We found that a minimum of three 5' and one 3' regions influence E8 gene expression during fruit ripening. DNA sequences that confer responsiveness to exogenous ethylene in unripe fruit are distinct from DNA sequences that are sufficient for expression during fruit ripening.

Journal Article↗
PubMed1992

A study of six common neuroanesthesia cases.

Certified Registered Nurse Anesthetists (CRNAs) provide anesthesia to a wide spectrum of patients, including those undergoing various neurosurgical procedures. While some CRNAs specialize in neuroanesthesia, most are involved on a more episodic basis. Using a case study format, this article reviews the pathophysiology associated with six common neurologic conditions the general practice CRNA may encounter. Important anesthesia considerations for each condition are discussed.

Adolescent↗
PubMed1991

Doppler evaluation of umbilical and uterine-arcuate arteries in the postdates pregnancy.

To assess the correlation between Doppler velocimetry and perinatal outcome in the postdates pregnancy, 75 women who were at least 41 weeks' gestation were evaluated twice weekly until delivery. Evaluation included Doppler velocimetry of the umbilical and uterine-arcuate arteries, as well as nonstress testing and amniotic fluid volume estimation. The mean umbilical artery systolic-diastolic ratio (S/D) was significantly higher in the pregnancies with subsequent abnormal perinatal outcomes than in those with normal outcomes (2.42 versus 2.19; P = .03). Using a receiver operating characteristic curve, an abnormal umbilical artery S/D was defined as 2.40 or greater. Using this value, sensitivity was 57.1% and specificity was 77.8%. Our study suggests that an umbilical artery S/D of 2.40, rather than the more traditionally accepted cutoff of 3.0, may be a useful threshold to identify those postdates pregnancies at high risk for abnormal perinatal outcome.

Adult↗
PubMed1991

Arrhythmias in the PACU. A review.

The patient emerging from anesthesia has been subjected to a myriad of predisposing causes of dysrhythmias. Adequate pain control; relief of anxiety; maintenance of proper ventilation and oxygenation; prompt treatment of hypothermia; accurate assessment of vital signs, electrolytes, hemoglobin, and hematocrit; observation for signs of hemorrhage; and continuous cardiac monitoring should be afforded every PACU patient. When dysrhythmias occur, prompt recognition, evaluation of possible causes, and appropriate interventions should be instituted.

Arrhythmias, Cardiac↗
PubMed1990

Selective reduction of multifetal pregnancies.

Selective reduction was carried out in 46 multifetal pregnancies by means of potassium chloride injection into the pericardial region of the fetus. There were three indications for the procedure: to improve perinatal outcome and to increase the likelihood that a term infant would be born in a multifetal pregnancy (34 women); to allow the birth of a healthy infant without the birth of a congenitally abnormal coexisting fetus (8 women); and to preserve a singleton pregnancy when the woman would otherwise have the whole pregnancy terminated (4 women). Of the 80 fetuses left after reduction 75 (94%) have survived. In 3 cases ultrasound scanning showed cardiac activity in the injected fetus 20-30 min after the initial injection despite 2 min of asystole immediately after the injection; repeated injection, carried out the same day, led to fetal death in all 3 cases. Selective reduction of multifetal pregnancies for the three indications described is an ethically justifiable option for the management of multifetal pregnancy, to which there are no public policy obstacles.

Congenital Abnormalities↗
PubMed1990

Transcriptional activation by heat and cold of a thiol protease gene in tomato.

We previously determined that low temperature induces the accumulation in tomato (Lycopersicon esculentum) fruit of a cloned mRNA, designated C14, encoding a polypeptide related to thiol proteases (MA Schaffer, RL Fischer [1988] Plant Physiol 87: 431-436). We now demonstrate that C14 mRNA accumulation is a response common to both high (40 degrees C) and low (4 degrees C) temperature stresses. Exposure of tomato fruit to 40 degrees C results in the accumulation of C14 mRNA, by 8 hours. This response is more rapid than that to 4 degrees C, but slower than the induction of many heat shock messages by 40 degrees C, and therefore unique. We have also studied the mechanism by which heat and cold exposure activate C14 gene expression. Both high and low temperature regulate protease gene expression through transcriptional induction of a single C14 gene. A hypothesis for the function of C14 thiol protease gene expression in response to heat and cold is discussed.

Journal Article↗
PubMed1990

Polygalacturonase Isozymes and Pectin Depolymerization in Transgenic rin Tomato Fruit.

We have previously described the construction and expression of a chimeric gene that allows developmentally regulated expression of tomato (Lycopersicon esculentum) polygalacturonase in ripening-impaired, mutant (rin) tomato fruit (JJ Giovannoni, D DellaPenna, AB Bennett, RL Fischer [1989] The Plant Cell 1: 53-63). We now show that expression of the chimeric polygalacturonase gene in rin tomato fruit resulted in the accumulation of all three polygalacturonase isozymes (PG1, PG2A, and PG2B). Polyuronide solubilization and polyuronide depolymerization both reached their maximal levels in transgenic rin fruit prior to the appearance of PG2 isozymes. These results demonstrate that PG1, PG2A, and PG2B all arise by differential processing of a single gene product and further suggest that the PG1 isozyme is sufficient to carry out both polyuronide solubilization and depolymerization in vivo.

Journal Article↗
PubMed1989

Transcriptional Analysis of Polygalacturonase and Other Ripening Associated Genes in Rutgers, rin, nor, and Nr Tomato Fruit.

We have studied the transcription of polygalacturonase (PG) and several other riponing-associated genes in wild-type tomato (Lycopersicon esculentum) fruit and three ripening-impaired mutants, rin, nor, and Nr. In wild-type fruit, the PG gene becomes transcriptionally active early in ripening and remains transcriptionally active during the ripening process. Fruit of the three ripening-impaired mutants, which have reduced levels of PG mRNA, have correspondingly reduced PG transcription rates. Other ripening-associated genes showed diverse patterns of expression in the ripening-impaired mutant backgrounds. These results indicate that transcriptional activation of the PG gene is an important control point regulating the expression of PG during ripening in wild-type fruit and that PG expression in rin, nor, and Nr fruit is blocked at the level of transcription. A comparison of PG transcription rates and mRNA levels with those of other ripening-associated genes suggests that posttranscriptional processes may also contribute to the large accumulation of PG mRNA during ripening.

Journal Article↗
PubMed1989

Expression of a chimeric polygalacturonase gene in transgenic rin (ripening inhibitor) tomato fruit results in polyuronide degradation but not fruit softening.

Tomato fruit ripening is accompanied by extensive degradation of pectic cell wall components. This is thought to be due to the action of a single enzyme, polygalacturonase, whose activity is controlled, at least in part, at the level of gene expression. At the onset of tomato fruit ripening, polygalacturonase enzyme activity, mRNA levels, and relative rate of gene transcription all increase dramatically. To elucidate the role of polygalacturonase during tomato fruit ripening, we utilized a pleiotropic genetic mutation, rin, that blocks many aspects of ripening, including the activation of polygalacturonase gene transcription. The polygalacturonase structural gene was ligated to a promoter that is inducible in mature rin fruit and inserted into the fruit genome, and plants were regenerated. This allowed expression of the polygalacturonase gene in transgenic rin fruit at a time corresponding to ripening in wild-type fruit. Expression of this gene resulted in the accumulation of active polygalacturonase enzyme and the degradation of cell wall polyuronides in transgenic rin fruit. However, no significant effect on fruit softening, ethylene evolution, or color development was detected. These results indicate that polygalacturonase is the primary determinant of cell wall polyuronide degradation, but suggest that this degradation is not sufficient for the induction of softening, elevated rates of ethylene biosynthesis, or lycopene accumulation in rin fruit.

Base Sequence↗
PubMed1989

Interaction of a developmentally regulated DNA-binding factor with sites flanking two different fruit-ripening genes from tomato.

To investigate mechanisms that control fruit development, we have begun experiments to identify proteins that control gene expression during tomato fruit ripening. We focused on the regulation of two different genes, E4 and E8, whose transcription is coordinately activated at the onset of fruit ripening. We report here that a DNA-binding protein specifically reacts with similar sequences flanking the E4 and E8 genes. The E4 binding site is at position -34 to -18 and, therefore, overlaps the region (TATA box) that in many eukaryotic genes serves to determine the efficiency and initiation site of transcription. In contrast, the E8 binding site is distal, located at -936 to -920 relative to the start of E8 gene transcription. Gel electrophoresis mobility retardation experiments indicate that the DNA binding activity that interacts with these two sites increases at the onset of fruit ripening. Taken together, these results suggest that this DNA-binding protein may function to coordinate E4 and E8 gene expression during fruit ripening.

Amino Acid Sequence↗
PubMed1989

Characterization of the glycinin gene family in soybean.

We characterized the structure, organization, and expression of genes that encode the soybean glycinins, a family of storage proteins synthesized exclusively in seeds during embryogenesis. Five genes encode the predominant glycinin subunits found in soybeans, and they have each been cloned, sequenced, and compared. The five genes have diverged into two subfamilies that are designated as Group-I and Group-II glycinin genes. Each glycinin gene contains four exons and three introns like genes that encode related proteins in other legumes. Two other genes have been identified and designated as "glycinin-related" because they hybridize weakly with the five glycinin genes. Although not yet characterized, glycinin-related genes could encode other glycinin subunit families whose members accumulate in minor amounts in seeds. The three Group-I glycinin genes are organized into two chromosomal domains, each about 45 kilobase pairs in length. The two domains have a high degree of homology, and contain at least five genes each that are expressed either in embryos or in mature plant leaves. Gel blot studies with embryo mRNA, as well as transcription studies with 32P-RNA synthesized in vitro from purified embryo nuclei, indicate that glycinin and glycinin-related genes become transcriptionally activated in a coordinated fashion early in embryogenesis, and are repressed coordinately late in seed development. In addition to transcriptional control processes, posttranscriptional events also are involved in regulating glycinin and glycinin-related mRNA levels during embryogenesis.

Amino Acid Sequence↗