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Biomedical subjects

G Koren

Publications and source records attributed to G Koren.

At least 127 records · Page 7Linked to original sources

Drug labeling and risk perceptions of teratogenicity: a survey of pregnant Canadian women and their health professionals.

There is a general perception that medicinal drugs are not safe in pregnancy despite the fact that fewer than 30 drugs have been shown to cause major malformations in humans. A large number of women need medications in pregnancy to treat pregnancy-induced conditions, acute illnesses, and chronic diseases. The objectives of this study were the following: (1) to characterize the perception of teratogenic risk by pregnant women and their partners and by health professionals and (2) to examine the most reassuring way to present data on a drug for nausea and vomiting of pregnancy that has been proven to be safe to the fetus. A convenience sample of pregnant Canadian women and their partners, pharmacists, nurses, physicians, and hospital workers were asked to choose the "safest" among four drugs by statements describing their safety. Although the text of all four was similar, the title and narrative were modified to be more or less "reassuring" by the use of more or less terms such as malformations and abnormalities. Health professionals rated the teratogenic risk significantly lower than the parents, but even they rated the drugs as not safe, despite a scientifically reassuring text. Sixty percent of the 240 participants, regardless of their perception of teratogenic risk, believed the four drugs were of similar risks. However, in the other 40%, the less "reassuring" text led to higher teratogenic perception, and the more reassuring options tended to decrease the false perception of teratogenic risk. It was concluded that in general, four different versions of reassuring text describing a scientifically proven safe drug in pregnancy did not lead expecting parents to believe they were safe. Among those who did not rank the four drugs as having equal safety/risk, the less "reassuring" text led to a higher perception of teratogenic risk. Even health professionals reading the labels describing safe drugs rated them as unsafe. Presently, the perception of teratogenic risk is strong even for safe drugs and is difficult to change even with evidence-based facts.

Drug Labeling↗

The effects of cocaine and nicotine on amino acid transport across the human placental cotyledon perfused in vitro.

The inhibitory effects of cocaine and nicotine on placental amino acid transport, as a mechanism contributing to intrauterine growth restriction, were investigated in the in vitro placental perfusion model. Amino acids that represent substrates for known placental transporters were selected: alanine (system A), glutamine (system N), phenylalanine and valine (system l), and arginine (system y(+)). Amino acid accumulation on the fetal side was measured in the absence of cocaine or nicotine (n = 7) and in the presence of 1.2 microg/ml cocaine (n = 6), 120 ng/ml nicotine (n = 6), or both (n = 6). Neither cocaine nor nicotine alone significantly inhibited alanine transport, whereas their combination did (P =.02). Significant inhibition of arginine transport was detected with nicotine (P =.007), cocaine (P =.01), and their combination (P =.01), whereas phenylalanine (P =.03, P =.04) and valine (P =.03, P =.04) transport was affected by cocaine and the combination of cocaine and nicotine, respectively. For glutamine, neither cocaine, nicotine, nor their combination had a statistically significant inhibitory effect. In conclusion, both cocaine and nicotine may contribute to fetal growth restriction by interfering with the activity of amino acids transporters that are necessary to maintain the nutrient gradients associated with normal fetal growth.

Amino Acids↗

Antenatal phenobarbital for prevention of intraventricular hemorrhage in preterm infants.

QUESTION: One of my patients, a 36-year-old, who has had three pregnancies and two live births, delivered her third baby at 32 weeks' gestation. Her first pregnancy was complicated by premature labour, which led to delivery at 30 weeks' gestation. She received antenatal phenobarbital before the first delivery because it was considered proven therapy for preventing intraventricular hemorrhage in preterm infants. I would like to know why it is no longer routinely used. ANSWER: Cumulative results from recent studies have failed to confirm the initial impression of effectiveness of antenatal phenobarbital. It is no longer recommended when preterm delivery is anticipated.

Cerebral Hemorrhage↗

Controversies in antenatal corticosteroid treatment.

QUESTION: I am following up a former preterm infant, born at 29 weeks' gestation after premature labour. This infant had a relatively benign hospital course and when discharged was not thought to have any complications of prematurity. Despite this, at 1 year old his neurologic examination is abnormal: head circumference is on the 3rd percentile for age (weight on the 25th percentile), and he has increased tone in his lower legs and a moderate developmental delay. His discharge letter indicated that he was exposed antenatally to many doses of dexamethasone. Could this have adversely influenced his neurologic outcome? ANSWER: Antenatal steroids are proven therapy for preventing respiratory distress syndrome and decrease both morbidity and mortality associated with prematurity. Use of multiple doses of antenatal steroids might adversely affect neurologic outcome. There is insufficient evidence to support routine use of multiple doses of antenatal steroids when delivery of a preterm infant is anticipated.

Betamethasone↗

Appraisal of drug therapy for nausea and vomiting of pregnancy: I. The placebo effect - methodological and practical considerations.

BACKGROUND: Despite that nausea and vomiting of pregnancy (NVP) is the most common medical problem during pregnancy, the placebo effect in the treatment of this condition has not been properly evaluated. METHODS: Two published randomized, controlled trials comparing the antiemetic effects of vitamin B6 with placebo were analyzed. RESULTS: When the severity of nausea or vomiting in the placebo groups at baseline was compared with that at the end of the trials, there was a clear time-dependent placebo effect that peaked between days 4 and 5. The placebo effect appeared to be more pronounced in nausea than in vomiting. CONCLUSIONS: There is a clear placebo effect on NVP. The effect appears to be stronger with nausea than with vomiting.

Female↗

Critical appraisal of drug therapy for nausea and vomiting of pregnancy: II. Efficacy and safety of diclectin (doxylamine-B6).

Nausea and vomiting of pregnancy is the most common condition in pregnancy and affects up to 80% of all pregnant women. There are a large number of pharmacological agents that are effective for the treatment of nausea and vomiting associated with conditions such as motion sickness and gastrointestinal conditions; however, their use in pregnancy is limited by the lack of sufficient data on their potential teratogenic effects. The efficacy of the delayed-release combination of doxylamine and pyridoxine (Bendectin, Diclectin) has been shown in several randomized, controlled trials. The present review aims to refute the unsubstantiated beliefs that Diclectin is unsafe when used in the treatment of nausea and vomiting of pregnancy.

Antiemetics↗

Varicella virus vaccine before pregnancy. Important breakthrough in protecting fetuses.

QUESTION: Now that the new varicella virus vaccine is available, should I vaccinate all my female patients of reproductive age who do not remember having had chickenpox in childhood? ANSWER: In North America, seven out of 10 women who do not remember having chickenpox in childhood actually had it and are immune. You should test their immunity and, if they are susceptible, vaccinate them. Ensure they are not pregnant at the time of vaccination because the vaccine's safety has not been proven.

Adolescent↗

Longitudinal change in the treatment of nausea and vomiting of pregnancy in Ontario.

BACKGROUND: Health problems associated with untreated nausea and vomiting of pregnancy (NVP) include maternal weight loss, dehydration, and electrolyte and acid-base disturbances. Negative social consequences include the deterioration of domestic, social and occupational function of the affected women. In 1994 it was documented that most physicians in Ontario tended not to treat women with NVP pharmacologically. PURPOSE: To investigate the longitudinal change in therapeutic practice of physicians, with respect to the treatment of NVP. SUBJECTS AND METHODS: A questionnaire was distributed to a randomly selected sample of physicians that included community-based family physicians, hospital-based family physicians, obstetricians and physicians who called the Motherisk Program for information. The participants were questioned about their choices in the pharmacological treatment of NVP. The data from the survey were compared with those from a previously published survey conducted in 1994. RESULTS: In 1999, 90.2% of physicians surveyed reported to have used pharmacological means to treat NVP. In 1999, 95% of the physicians surveyed reported to have prescribed doxylamine succinate-pyridoxine hydrochloric acid (Diclectin), and 11% prescribed dimenhydrinate (Gravol) to treat NVP. These results are significantly different from those found in 1994 (90% prescribed Gravol as the first choice). CONCLUSIONS: In 1999, temporally related to various educational efforts, physicians offered treatment for NVP more readily, including the drug recommended by the regulatory agency. These changes may explain in part the recently documented decrease in hospitalizations due to NVP in Canada.

Chi-Square Distribution↗

Does breastfeeding have an effect on intelligence?

QUESTION: A young mother under my care is concerned because she has decided not to breastfeed and was told by several people that formula feeding will cause the baby not to be "as smart." Is this based on real science? ANSWER: Studies during the last decade have shown breastfeeding to be associated with higher intelligence in young children. Better controlled and more recent studies have shown that this association is probably not proof of causation, because mothers who decide to breastfeed tend to be better educated and more socioeconomically advantaged than those who decide to use formula. After controlling for these differences, the effect tends to disappear.

Adult↗

Occupational exposure to inhaled anesthetic. Is it a concern for pregnant women?

QUESTION: Two of my pregnant patients are exposed to inhaled anesthetic on the job. One is an anesthetist, and the other is a veterinarian. They have both expressed concern about this exposure. How should I advise them? ANSWER: Occupational exposure to waste anesthetic gas is not associated with increased risk of major malformations. Risk of spontaneous abortion might be slightly increased, however. This risk can be reduced, if not eliminated, by good gas scavenging systems.

Abortion, Spontaneous↗

Reporting bias in retrospective ascertainment of drug-induced embryopathy.

The rate of congenital malformations after first-trimester exposure to itraconazole was four times higher when ascertained retrospectively than prospectively (13.0 vs 3.2%, p=0.006). Reporting bias in retrospective studies should be acknowledged in interpretation of such data.

Abnormalities, Drug-Induced↗

Purification and preliminary characterization of a cardiac Kv1.5 repressor element binding factor.

We have previously demonstrated that the cell-specific expression of Kv1.5 promoter is regulated by a silencer (Kv1.5 repressor element; KRE) containing a dinucleotide-repetitive element, (GT)19(GA)1(CA) 15(GA)16. Electromobility gel shift assays (EMSAs) of KRE with GH3 nuclear extracts detected a unique DNA-protein complex, which was not detectable in Chinese hamster ovary or COS-7 cells. We further delineated KRE and determined that a 52-bp fragment that contained a (GT)10(GA)1(CA)10 dinucleotide-repetitive element was sufficient for silencer activity. EMSAs using nuclear extracts isolated from the heart and from GH3 cells demonstrated that the 52-bp element formed specific and identical gel shift effects. These complexes were not detectable in EMSA experiments with liver nuclear extracts. Magnetic DNA affinity purification and UV cross-linking experiments identified a 27-kDa KRE binding factor (KBF) in GH3 cell nuclear extracts. Purified KBF reacted specifically with double-stranded KRE, abolishing the formation of multimeric KRE-DNA complexes. Thus, the interaction between KRE and KBF may play an important role in regulating the GH3- and cardiac-specific expression of Kv1.5.

Animals↗

Ile-177 and Ser-180 in the S1 segment are critically important in Kv1.1 channel function.

Ile-177 and Ser-180 are conserved residues in the first transmembrane segment (S1) of the Shaker, Shab, Shaw, and Shal subfamilies of voltage-gated K+ channels. Here we report that the mutation of these residues in Kv1.1 to leucine, proline, or arginine abolished the expression of outward potassium currents in Xenopus oocytes. Co-injection of these mutant cRNAs and wild type Kv1.1 cRNA into Xenopus oocytes exerted a potent dominant negative effect resulting in the suppression of Kv1.1-encoded currents. Transient transfection experiments of COS-7 cells revealed that the S1 mutants directed the synthesis of Kv1.1 polypeptides. Quantitative co-immunoprecipitation assays revealed that most of the S1 mutants co-assembled and formed both homo- and heteromultimeric complexes. Furthermore, the mutated polypeptides could reach the plasma membranes of transfected Sol8 cells. We conclude that mutations of Ile-177 and Ser-180 do not interfere with either the assembly of multimeric channel complexes or the targeting of these complexes to the plasma membrane. It is likely that these residues are involved in helix-helix interactions that are critical to the proper functioning of voltage-gated potassium channels.

Amino Acid Sequence↗

Hydroxyurea use during pregnancy: a case report in sickle cell disease and review of the literature.

A patient being treated for sickle cell disease with hydroxyurea (1 g/d) conceived, and drug treatment was discontinued at nine weeks gestational age. The pregnancy and delivery were complicated by vaso-occlusive crises. A healthy male infant was born at 39 weeks with no evidence of congenital malformations. A literature review, including this case, suggests that the risk of hydroxyurea exposure during in pregnancy may have been overestimated. Further studies are required to determine its safety in pregnancy.

Adult↗

Risks for FAS.

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Female↗