Biomedical subjects

Richard M Smiley

Publications and source records attributed to Richard M Smiley.

4 recordsLinked to original sources

PubMed2003

G-protein beta(3) subunit 825 C/T polymorphism is associated with weight gain during pregnancy.

A common polymorphism (C825T) of the gene encoding the G-protein beta(3) subunit has been associated with obesity. We examined the hypothesis that this polymorphism affected weight gain during pregnancy. Two hundred and ninety-four women with uncomplicated term deliveries of singleton pregnancies were genotyped. Women homozygous for the T allele (TT) gained significantly more weight than women carrying the C allele (CC and CT groups) (P = 0.006) and had a significantly higher pre-pregnancy body mass index (P = 0.02). The C825T polymorphism of the G-protein beta(3) subunit gene, known to be associated with obesity, is a determinant of weight gain during pregnancy.

Adult↗

PubMed2002

Disproportionate decrease in alpha- compared with beta-adrenergic sensitivity in the dorsal hand vein in pregnancy favors vasodilation.

BACKGROUND: Altered vascular responses to adrenergic agonists during pregnancy are thought to play an important role in the regulation of blood pressure and placental blood flow. Because alpha1-adrenergic and beta2-adrenergic sensitivity act in opposing directions to determine vascular tone, we simultaneously evaluated alpha-adrenergic-mediated vasoconstriction and beta-adrenergic-mediated vasodilation in dorsal hand veins during and after pregnancy. METHODS AND RESULTS: Twenty healthy pregnant women were studied at 32 to 37 weeks of gestation and again 12 weeks after delivery. Vascular response to phenylephrine (PE) and isoproterenol (ISO) was measured in a dorsal hand vein using the linear variable differential transformer technique. The dose of PE resulting in 50% constriction (CD50) was determined. The response to ISO was measured after the PE preconstriction. Pregnant and postpartum values, expressed as geometric mean (95% CI), were compared by paired t test. alpha-Adrenergic sensitivity during pregnancy (CD50 2.7 micro g/min [95% CI, 1.5 to 5.0]) was markedly decreased, approximately 7-fold, compared with postpartum (0.4 micro g/min [95% CI, 0.3 to 0.7] [P<0.01]). beta-Adrenergic vasodilation was also attenuated during pregnancy. The ED50 of ISO (dose of ISO resulting in 50% of the maximal response, E(max)) was greater during pregnancy (20 ng/min [95% CI, 11 to 35]) than postpartum (8 ng/min [95% CI, 5 to 12]) (P<0.05). ISO E(max) was also significantly less during pregnancy (81% [95% CI, 65 to 97] compared with postpartum (105% [95% CI, 97 to 113]) (P<01.01). CONCLUSIONS: Normal pregnancy is characterized by decreased venous sensitivity to both alpha1-adrenoceptor-mediated vasoconstriction and beta2-adrenoceptor-mediated vasodilation. The greater decrease in alpha1 compared with beta2 response may contribute to the vasodilated state characteristic of human pregnancy.

Adolescent↗

PubMed2002

beta2-Adrenergic receptor genotype and preterm delivery.

OBJECTIVE: Our purpose was to determine whether the functional genetic polymorphisms of the beta(2)-adrenergic receptor (beta(2)AR) that result in changes in amino acid residues 16 and 27 are associated with preterm delivery. STUDY DESIGN: A case-control study comparing the distribution of beta(2)AR genotype between 251 Hispanic women delivered at term and 28 Hispanic women delivered preterm. Preterm delivery was defined as spontaneous onset of labor resulting in delivery before 37 weeks of gestation, in a singleton pregnancy, with no apparent etiology for preterm labor and delivery. Genomic DNA was isolated from peripheral blood, and beta( 2)AR alleles were identified by established techniques. RESULTS: Only one woman (4%) with preterm labor was homozygous for Arg16 versus 79 (31%) in the control group (P =.01, odds ratio 0.08). There was no association of preterm labor with genotype at position 27. CONCLUSION: Our data demonstrate that homozygosity for Arg16, which in vitro is associated with decreased down-regulation of the beta(2)AR, protects from preterm delivery.

Adult↗

PubMedDate not supplied

Epinephrine is not a useful addition to intrathecal fentanyl or fentanyl-bupivacaine for labor analgesia.

BACKGROUND AND OBJECTIVES: Intrathecal fentanyl provides effective labor analgesia for a limited time with frequent side effects. We evaluated the effects of adding epinephrine to intrathecal fentanyl with and without bupivacaine. METHODS: Eighty healthy, term, nulliparous parturients with cervical dilation of 5 cm or less received combined spinal-epidural (CSE) analgesia. Subjects were randomized in a double-blind fashion to 1 of 4 intrathecal solutions containing fentanyl 35 microg with either saline (F); bupivacaine 2.5 mg + saline (FB); bupivacaine 2.5 mg + epinephrine 100 microg (FBE); or epinephrine 100 microg + saline (FE). Patients were evaluated for visual analog pain score, duration of spinal analgesia (time until patient request for additional analgesia), nausea/vomiting, pruritus, sensory and motor block, maternal blood pressure, and fetal heart rate (FHR). RESULTS: Intrathecal bupivacaine significantly prolonged fentanyl analgesia with or without epinephrine (P =.018), but epinephrine did not significantly prolong the duration of fentanyl alone or with bupivacaine (F, 92 +/- 39 minutes; FB, 125 +/- 31 minutes; FBE, 134 +/- 42 minutes; and FE, 117 +/- 48 minutes). Intrathecal epinephrine was associated with a higher incidence of severe nausea (P =.001), and the FBE group had more lower extremity weakness (P =.047). There was no difference in the incidence of severe pruritus, FHR deceleration, or delivery outcome between the groups. CONCLUSIONS: These results suggest that intrathecal epinephrine does not prolong the duration of fentanyl or fentanyl with bupivacaine for labor analgesia in nulliparous parturients. Additionally, intrathecal epinephrine did not decrease the incidence of side effects and therefore cannot be recommended.

Adult↗