Biomedical subjects
Publications and source records attributed to D C Mayer.
We report the first case of a severe anaphylactic or anaphylactoid reaction to sodium ferric gluconate complex in a pregnant patient. Sodium ferric gluconate complex is felt to be one of the safest forms of iron therapy during pregnancy. This case highlights the need for extreme caution and vigilance in pregnant patients receiving any type of parenteral iron therapy.
A member of a Plasmodium receptor family for erythrocyte invasion was identified on chromosome 13 from the Plasmodium falciparum genome sequence of the Sanger Centre (Cambridge, U.K.). The protein (named BAEBL) has homology to EBA-175, a P. falciparum receptor that binds specifically to sialic acid and the peptide backbone of glycophorin A on erythrocytes. Both EBA-175 and BAEBL localize to the micronemes, organelles at the invasive ends of the parasites that contain other members of the family. Like EBA-175, the erythrocyte receptor for BAEBL is destroyed by neuraminidase and trypsin, indicating that the erythrocyte receptor is a sialoglycoprotein. Its specificity, however, differs from that of EBA-175 in that BAEBL can bind to erythrocytes that lack glycophorin A, the receptor for EBA-175. It has reduced binding to erythrocytes with the Gerbich mutation found in another erythrocyte, sialoglycoprotein (glycophorin C/D). The interest in BAEBL's reduced binding to Gerbich erythrocytes derives from the high frequency of the Gerbich phenotype in some regions of Papua New Guinea where P. falciparum is hyperendemic.
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The purpose of this study was to investigate whether GABA(A) receptors in the dorsal striatum regulate basal or stimulant-induced behaviors. Correspondingly, the question of possible GABA(A) receptor control of neuropeptide mRNA expression in nigrostriatal neurons was addressed. The GABA(A) receptor antagonist, bicuculline, was unilaterally or bilaterally microinjected into the dorsal striatum of rats in a series of 3 studies. In the first study, unilateral administration of 10-50 ng/microliter of bicuculline did not alter behavior. However, 250 ng/microliter bicuculline produced motor dyskinesias and/or seizures. In the second study, 100 ng/microliter bicuculline administered unilaterally prior to saline or amphetamine treatment, produced mild twitching in 61% of rats but did not affect amphetamine (2.5 mg/kg, i.p.)-induced behavioral activity, specifically rearing and sniffing. In the third study, 75 ng/microliter of bicuculline was administered unilaterally or bilaterally into the striatum in two separate experiments. Administration of bicuculline either unilaterally or bilaterally produced mild transient twitching of the forelimbs but did not affect behaviors induced by the selective D(1) receptor agonist SKF-82958 (0.5 mg/kg, s.c.). Three hours after unilateral bicuculline administration, the brains were removed and processed for quantitative in situ hybridization. Bicuculline did not significantly affect the basal or SKF-82958-induced increase in preprodynorphin or substance P mRNA expression in striatonigral neurons on the side of injection. These data suggest that blockade of GABA(A) receptors in the dorsal striatum does not affect dopamine agonist-stimulated behaviors or neuropeptide mRNA expression in striatonigral neurons in the rat striatum.
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Myofibroblasts are unusual cells that share morphological and functional features of muscle and nonmuscle cells. Such cells are thought to control liver blood flow and kidney glomerular filtration rate by having unique contractile properties. To determine how these cells achieve their contractile properties and their resemblance to muscle cells, we have characterized two myofibroblast cell lines. Here, we demonstrate that myofibroblast cell lines from kidney mesangial cells (BHK) and liver stellate cells activate extensive programs of muscle gene expression including a wide variety of muscle structural proteins. In BHK cells, six different striated myosin heavy chain isoforms and many thin filament proteins, including troponin T and tropomyosin are expressed. Liver stellate cells express a limited subset of the muscle thick filament proteins expressed in BHK cells. Although these cells are mitotically active and do not morphologically differentiate into myotubes, we show that MyoD and myogenin are expressed and functional in both cell types. Finally, these cells contract in response to endothelin-1 (ET-1); and we show that ET-1 treatment increases the expression of sarcomeric myosin.
OBJECTIVE: Our purpose was to determine the cardiac effects of oxytocin in the isolated perfused rat heart model and to see whether pregnancy or pharmacologic levels of magnesium modifies the hormone's action. STUDY DESIGN: Hearts were excised from 30 female Sprague-Dawley rats (15 pregnant, 15 nonpregnant) and attached to a Langendorf's apparatus. Heart rate, left ventricular systolic pressure, and contractility were measured. Hearts were exposed serially to 2, 4, and 6 mU/ml concentrations of oxytocin. The experiment was repeated in 15 pregnant animals at a magnesium level of 5 mEq/L. RESULTS: Hearts from pregnant rats had lower heart rates than did hearts from nonpregnant animals. Oxytocin exposure diminished heart rate but increased left ventricular systolic pressure and contractility in a dose-dependent manner. Pregnancy did not alter this response. Magnesium levels of 5 mEq/L reversed the effects of oxytocin on contractility and left ventricular systolic pressure. CONCLUSION: Oxytocin is a negative chronotropic and positive inotropic agent in hearts from pregnant and nonpregnant rats. Magnesium reserves the positive inotropic effects of oxytocin.
To determine whether women who receive continuous epidural analgesia for labor and delivery are more likely to receive antibiotic therapy compared to those parturients who do not use epidural analgesia, a chart review was performed for 300 women 100 in each group using narcotics alone epidural alone, or parenteral narcotics followed by epidural analgesia. While only 2% of women with narcotics alone developed an intrapartum temperature > or = 37.8 degrees C, 16% and 24% of women with epidural use alone or in addition to narcotics did so, respectively. Antibiotic administration was increased among women utilizing epidural analgesia, exclusively or following parenteral narcotics. No parturient with culture or pathological evidence of chorioamnionitis had maternal temperature elevation as an isolated finding. A probable causal relationship between maternal temperature elevation and epidural use in labor is supported. Rather than treating all women with temperature elevations and epidurals for presumed chorioamnionitis, it is reasonable to target treatment to those with fetal tachycardia, meconium stained fluid, or abnormal amniotic fluid studies.
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OBJECTIVE: To determine the cardiac effects of relaxin in the isolated, perfused rat heart model, and to see if pregnancy modifies the hormone's actions. METHODS: Hearts were excised from 18 female Sprague-Dawley rats (ten pregnant, eight nonpregnant) and attached to a Langendorff apparatus. Left ventricular systolic pressure, heart rate, and contractility were measured. Hearts were exposed serially to 0.5, 1.0, 2.0, 4.0, 8.0, and 16.0 ng/mL concentrations of recombinant human relaxin. RESULTS: Hearts from pregnant rats had lower heart rates than those from nonpregnant animals. Relaxin increased heart rate, left ventricular systolic pressure, and contractility in a dose-dependent fashion. Pregnancy did not modify this response. CONCLUSION: Recombinant human relaxin is a potent inotropic and chronotropic agent. The effects coupled with the physiologic increase of relaxin during human pregnancy indicate that relaxin may be involved in the cardiovascular changes of pregnancy.
Untreated hyperthyroidism during pregnancy is associated with increased maternal and perinatal morbidity. Some features of this disease simulate preeclampsia, which may encourage delivery of the fetus. We report a case of poorly controlled hyperthyroidism associated with generalized seizures, where patient management was directed at a diagnosis of preeclampsia-eclampsia. Although the presence of eclampsia and marked hyperthyroidism is very rare, this case illustrates the importance of aggressive medical management of hyperthyroidism. A 17-year-old gravida was diagnosed with hyperthyroidism at 15 weeks' gestation. At 26 weeks' gestation, she was admitted to the hospital after noting edema of the upper and lower extremities, nausea, vomiting, shortness of breath, and a cough. At admission, she was hypertensive, tachycardic, and dyspneic. The patient was believed to have preeclampsia with pulmonary edema complicated by hyperthyroidism. We initiated magnesium sulfate therapy and administered several bolus doses of hydralazine, with little effect on blood pressure. Oliguria was noted, and a pulmonary artery catheter was inserted. Hours later, generalized seizure activity occurred, and a decision was made for abdominal delivery. Postoperatively, cardiovascular function stabilized. On postoperative day 3, we received the results of the thyroid function tests obtained at admission, which suggested a markedly hyperthyroid condition. Untreated or poorly treated hyperthyroidism may present a clinical picture similar to preeclampsia. In our case, both disease processes coexisted in their severest forms. It is possible, although completely unproven, that a relationship exists between poorly controlled hyperthyroidism and preeclampsia-eclampsia. More importantly, accurate diagnosis of hyperthyroidism should lead to prompt medical or surgical management, thereby decreasing maternal and perinatal morbidity.
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In this case report, NTG provided sufficient uterine relaxation to allow difficult twin extraction at Caesarean delivery. Administration of NTG in this situation was controversial, and if it had not been effective, time may have been lost before general anaesthesia could have been induced. Nitroglycerin merits further evaluation as an antepartum uterine relaxant, but the initial experience is encouraging.
A high incidence of postdural puncture headache (PDPH) occurs after spinal anesthesia for cesarean section. To examine this problem, a study was conducted with the recently developed 24-gauge Sprotte and 27-gauge Quincke needles in patients undergoing elective and emergency cesarean section (n = 298). The needle to be used was assigned in a random manner: group I, 27-gauge Quincke (n = 147); group II, 24-gauge Sprotte (n = 151). During the postoperative period, patients were visited daily and asked specifically about the presence and severity of headache. The overall incidence of PDPH was 2% (n = 6), five in the Quincke group (3.5%) and one in the Sprotte group (0.7%). There was no significant difference in the incidence of PDPH between the two groups. Five headaches were classified as mild, and only one was moderate to severe. All headaches resolved quickly with conservative management and without blood patch. The authors conclude that the choice between a 27-gauge Quincke and a 24-gauge Sprotte needle does not influence the incidence of PDPH after spinal anesthesia for cesarean section.
The hemodynamics of critical aortic stenosis in the fetus make it a ductus-dependent cardiac defect because the ductus arteriosus supplies blood not only to the descending aorta but also to the aortic arch and coronary vessels. In utero closure of the ductus arteriosus has been reported in association with tetralogy of Fallot, truncus arteriosus, maternal use of prostaglandin inhibitors, and as idiopathic events. This is the first report of a ductus-dependent congenital heart defect (critical aortic stenosis) where treatment with indomethacin, a prostaglandin synthetase inhibitor, precipitated premature closure of the ductus and hydrops fetalis. Review of reported cases of premature closure of the ductus show that acute, in utero closure of the ductus in a fetus with limited cardiopulmonary reserves has a worse prognosis than with previously reported cardiac anomalies. This study strongly supports published concerns of increased perinatal morbidity and mortality when fetuses are exposed to prostaglandin inhibitors in utero, and shows that ductus-dependent fetal cardiac defects are contraindications to the maternal use of prostaglandin inhibitors during pregnancy.
The effects of hemorrhagic shock and retransfusion on the activities of two endogenous antioxidant enzymes, catalase and superoxide dismutase, were studied in male New Zealand white rabbits. Following instrumentation and stabilization, blood was withdrawn to reduce mean arterial pressure to 35 mmHg (SHOCK). After 60 min of shock, the warmed autologous blood was infused and the animals were allowed to recover for an additional 30 min (RETRANS). CONTROL animals were instrumented but not bled or transfused. A 60 min period of hemorrhagic shock had no significant effect on tissue or plasma activities of catalase or superoxide dismutase. However, transfusion following hemorrhagic shock resulted in an increase in catalase activity of nearly two-fold in the liver and five-fold in the small intestine. In contrast, superoxide dismutase activity remained unchanged after retransfusion in other tissues and in plasma. These results indicate that superoxide dismutase and catalase activities may be preserved or even induced following transfusion for hemorrhagic shock.