Flufenamic acid as an inducer of mitochondrial permeability transition

To assess the mechanism by which mitochondrial permeability transition (MPT) is induced by the nonpolar carboxylic acids, we investigated the effects of flufenamic acid (3'-trifluoromethyl diphenylamine-2-carboxylic acid, FA) on mitochondrial respiration, electrical transmembrane potential difference (delta psi), osmotic swelling, Ca2+ efflux, NAD(P)H oxidation and reactive oxygen species (ROS) generation. Succinate-energized isolated rat liver mitochondria incubated in the absence or presence of 10 microM Ca2+, 5 microM ruthenium red (RR) or 1 microM cyclosporin A (CsA) were used. The dose response-curves for both respiration release and delta psi dissipation were nearly linear, presenting an IC50 of approximately 10 microM and reaching saturation within 25-50 microM, indicating that FA causes mitochondrial uncoupling by a protonophoric mechanism. Within this same concentration range FA showed the ability to induce MPT in energized mitochondria incubated with 10 microM Ca2+, followed by delta psi dissipation and Ca2+ efflux, and even in deenergized mitochondria incubated with 0.5 mM Ca2+. ADP, Mg2+, trifluoperazine (TFP) and N-ethylmaleimide (NEM) reduced the extent of FA-promoted swelling in energized mitochondria by approximately one half, whereas dithiothreitol (DTT) slightly enhanced it. NAD(P)H oxidation and ROS generation (H2O2 production) by mitochondria were markedly stimulated by FA; these responses were partly prevented by CsA, suggesting that they may be implicated as both a cause and effect of FA-induced MPT. FA incubated with mitochondria under swelling assay conditions caused a decrease of approximately 40% in the content of protein thiol groups reacting with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB). The present results are consistent with a ROS-intermediated sensitization of MPT by a direct or indirect FA interaction with inner mitochondrial membrane at a site which is in equilibrium with the NAD(P)H pool, namely thiol groups of integral membrane proteins.

Achyrocline satureioides essential oils from southern Brazil and Uruguay

The essential oils of the aerial parts of Achyrocline satureioides (D.C.) Lam., a regional medicinal plant, from different collection locations in the South of Brazil and Uruguay were examined by GC and GC-MS. Monoterpene and sesquiterpene hydrocarbons were the main fractions of both the oils from Brazil and Uruguay. The oxygenated monoterpenes and sequiterpenes were at much lower percentage in both samples. The Uruguayan samples have 1,8-cineole which is not present in the Brazilian samples and has not been reported in other samples from Brazil. The results indicated a high biodiversity of the native populations of A. satureioides.

Structural and in vivo studies of metal chelates of Ga(III) relevant to biomedical imaging

The solution chemistry and structure of the complex of the triazamacrocyclic ligand NOTP (1,4,7-triazacyclononane-1,4,7-tris(methylenephosphonate)) with Ga3+ in D2O have been investigated by 1H, 71Ga and 31P NMR spectroscopy. These NMR results show the presence of a 1:1 Ga(NOTP)3- complex, with a highly symmetrical, pseudo-octahedral geometry, possibly with a C3 axis. The 1H spectrum shows that the triazamacrocyclic chelate ring is very rigid, with all the ring protons non-equivalent. The complex is stable in aqueous solution in a wide pH range. Its high thermodynamic stability agrees well with previous results from biodistribution and gamma imaging studies in Wistar rats with 67Ga3+ chelates of triaza macrocyclic ligands, which showed that the neutral chelates 67Ga(NOTA) (where NOTA is 1,4,7-triazacyclononane-1,4,7-triacetate) and 67Ga(NOTPME) (where NOTPME is 1,4,7-triazacyclononane-1,4,7-tris(methylenephosphonate monoethylester)) have similar in vivo behaviour, with high stability and rapid renal excretion, but the high negatively charged 67Ga(NOTP)3- has a considerably slower kidney uptake and elimination.

Effect of prolonged asphyxia on skin blood flow in fetal lambs

OBJECTIVE

To determine the effect of a prolonged period of asphyxia on skin blood flow, a potential indicator of fetal cardiovascular responses to asphyxia, in the chronically catheterized fetal lamb.

METHODS

Eight chronically instrumented pregnant ewes were studied at 118 +/- 1 days' gestation. After a control period, fetal acid-base status was assessed and regional blood flows were determined with dye-labeled microspheres. Fetal asphyxia was then induced by partial umbilical cord occlusion, decreasing fetal arterial oxygen pressure to 15 torr while maintaining pH above 7.28. Fetal cardiovascular status was monitored continuously. Fetal acid base status was evaluated every 10-15 minutes during cord occlusion. Regional blood flow determinations were repeated after 90 minutes of stable asphyxia. Results are expressed as the mean +/- standard error. Student t test for paired data was used to compare hemodynamic, acid-base, and regional blood flow determinations before cord occlusion and after 90 minutes of asphyxia.

RESULTS

There was a significant increase in blood flow to the fetal scalp from a control value of 52 +/- 8 mL per minutes per 100 g to 175 +/- 30 mL per minute per 100 g at 90 minutes of asphyxia (P =.01). Similarly, there was an increase in blood flow to the skin overlying the fetal hindquarter from 39 +/- 12 mL per minute per 100 g during control to 153 +/- 47 mL per minute per 100 g at asphyxia (P =.038).

CONCLUSION

In the chronically instrumented fetal lamb, a 90-minute period of asphyxia produced by partial cord occlusion resulted in a significant increase in blood flow to the fetal skin.

Organic compounds in the extrapalial fluid and haemolymph of Anodonta cygnea (L.) with emphasis on the seasonal biomineralization process

Bivalve mollusks, such as the freshwater mussel Anodonta cygnea, show seasonal changes in calcification. This cycle of calcification must either be a cause or a consequence for seasonal fluctuations in the organic composition of the animal's fluids, haemolymph and extrapallial fluid, the liquid media for biomineralization. We monitored the fluids of A. cygnea, throughout a 1-year cycle, for the presence of organic constituents, known to be important for biomineralization, such as proteins, glycosaminoglycans (GAGs) and hexosamines. Proteins were subjected to further study, namely through the total amino acid determination and fraction separation by agarose gel electrophoresis. GAG levels were fairly constant throughout the year, with a maximum concentration in July and a minimum in January, a feature also detected for glucosamine, although with higher fluctuations. Proteins showed highly increased concentrations during June and July, both in total amounts and individual fractions. All fractions showed similar trends throughout the year, with lowest general levels in October, the starting month of a period when some fractions were not detectable at all. All fractions ended this low period in May, when a sometimes-important increase could be detected. As to the total amino acid composition of the fluids, the general trend followed that of proteins, except for ornithine (Orn), a non-proteic amino acid. The overall fluctuations detected in the biological fluids of A. cygnea suggest that the main variation related to the calcification cycle must be quantitative, since no different compounds appear in specific periods, to achieve also specific results.

Variability in the interpretation of microsatellite patterns with different electrophoretic conditions

Microsatellite markers permit the analysis of microsatellite instability and loss of heterozygosity. Frequently, the allelotypes of microsatellites are interpreted in the presence of numerous bands in gels. The importance of different gel electrophoresis conditions in the interpretation of microsatellite patterns was tested. Microsatellite markers were used to amplify DNA from gastric cancer samples and adjacent gastric mucosa. Polymerase chain reaction (PCR) products were separated by electrophoresis through 7% polyacrylamide gels containing either 5.6 M urea and 32% formamide or 7 M urea. PCR reactions separated on urea/formamide gels resulted consistently in clear allele definition (one or two bands), whereas 7 M urea gels resulted in allele patterns that comprised multiple bands. Analysis of microsatellite abnormalities using nonformamide gels gave false negative results in just under a third of cases (four of 13). In conclusion, the interpretation of microsatellite alterations in cancer DNA is improved by using electrophoresis conditions that result in complete DNA denaturation, such as urea/formamide/acrylamide gel electrophoresis.

Marked differences in the frequency of microsatellite instability in gastric cancer from different countries

OBJECTIVE

Previous studies have reported variable rates of microsatellite instability (MSI) in gastric cancer. We investigated the frequency of MSI in invasive gastric carcinoma of patients from three geographic regions.

METHODS

Genomic DNA from gastric cancer and nontumor tissue from 22 Korean, 20 Colombian, and 26 U.S. patients was amplified with five microsatellite markers.

RESULTS

MSI was more frequently seen in gastric cancer from Korea, affecting 50% of patients, in contrast with gastric cancers from the U.S. (7%) and Colombia (15%) (p = 0.003 and p = 0.03, respectively). MSI at one locus was significantly more frequent in gastric cancer from individuals >65 yr (p = 0.01). MSI was similarly associated with both diffuse and intestinal types of gastric cancer.

CONCLUSIONS

MSI affects the two major histological types of gastric cancer, and was more frequent in gastric cancer from Korea than in the other countries, suggesting that the relative importance of different pathways of gastric carcinogenesis may vary in diverse regions of the world.

Fluoxetine interacts with the lipid bilayer of the inner membrane in isolated rat brain mitochondria, inhibiting electron transport and F1F0-ATPase activity

The effects of fluoxetine on the oxidative phosphorylation of mitochondria isolated from rat brain and on the kinetic properties of submitochondrial particle F1F0-ATPase were evaluated. The state 3 respiration rate supported by pyruvate + malate, succinate, or ascorbate + tetramethyl-p-phenylenediamine (TMPD) was substantially decreased by fluoxetine. The IC50 for pyruvate + malate oxidation was approximately 0.15 mM and the pattern of inhibition was the typical one of the electron-transport inhibitors, in that the drug inhibited both ADP- and carbonyl cyanide m-chlorophenylhydrazone (CCCP)-stimulated respirations and the former inhibition was not released by the uncoupler. Fluoxetine also decreased the activity of submitochondrial particle F1F0-ATPase (IC50 approximately 0.08 mM) even though K0.5 and activity of Triton X-100 solubilized enzyme were not changed substantially. As a consequence of these effects, fluoxetine decreased the rate of ATP synthesis and depressed the phosphorylation potential of mitochondria. Incubation of mitochondria or submitochondrial particles with fluoxetine under the conditions of respiration or F1F0-ATPase assays, respectively, caused a dose-dependent enhancement of 1-anilino-8-naphthalene sulfonate (ANS) fluorescence. These results show that fluoxetine indirectly and nonspecifically affects electron transport and F1F0)-ATPase activity inhibiting oxidative phosphorylation in isolated rat brain mitochondria. They suggest, in addition, that these effects are mediated by the drug interference with the physical state of lipid bilayer of inner mitochondrial membrane.

Characterisation of 67Ga3+ complexes of triaza macrocyclic ligands: biodistribution and clearance studies

The 67Ga3+ complexes of three triazamacrocycles, 1,4,7-triazacyclononane-N,N',N''-triacetic acid (NOTA), its phosphonate analog 1,4,7-triazacyclononane-N,N',N''-tris(methylenephosphonic) acid (NOTP), and the monoethyl ester of NOTP, 1,4,7-triazacyclononane-N,N',N''-tris (methylenephosphonate-monoethylester) (NOTPME) were studied for possible use as radiopharmaceuticals. Biodistribution studies and gamma imaging were performed in Wistar rats. The present results demonstrated that all the macrocyclic complexes studied display renal clearance and are almost completely eliminated within 24 h. The [67Ga](NOTP)3- chelate, with a large negative charge, has a considerably slower uptake and elimination by the kidneys than the neutral [67Ga](NOTA) and [67Ga](NOTPME) chelates. We have thus demonstrated a charge-clearance relationship for a series of stable and well characterized complexes. The high stability and rapid renal excretion properties displayed by the NOTA and NOTPME chelates support their possible application as imaging agents for kidney structural and functional studies.

The placental transfer and fetal effects of levobupivacaine, racemic bupivacaine, and ropivacaine

BACKGROUND

The purposes of this study were to assess the effects of levobupivacaine on uterine blood flow and fetal well-being and to compare its placental transfer with that of bupivacaine and ropivacaine.

METHODS

After a control period, pregnant ewes that were fitted with instruments for long-term monitoring were randomized to receive a two-step intravenous infusion of levobupivacaine, bupivacaine, or ropivacaine, in a blinded manner, for 1 h. Maternal and fetal hemodynamics were monitored during the study. Arterial blood samples were drawn at 30 and 60 min of infusion from the mother and fetus to determine the acid-base status (60 min only) and serum drug concentrations. The fetal brain, heart, liver, lungs, adrenal glands, and kidneys were obtained to measure tissue drug levels.

RESULTS

Maternal blood pressure, central venous and intraamniotic pressures, acid-base status and uterine blood flow were unaffected by any drug infusion. In contrast to the other two local anesthetics, the infusion of bupivacaine was associated with a small but significant decrease in the ewe's heart rate. At the end of the study, the heart rate in the bupivacaine-treated animals was significantly less than in the animals treated with the other two drugs. All fetuses were in good condition at the start of study, and none of the local anesthetics affected fetal well-being. No significant differences were found among the three drugs in the maternal serum, fetal serum, fetal tissue concentrations, and tissue:serum concentration ratios.

CONCLUSIONS

Levobupivacaine was similar to bupivacaine and ropivacaine in causing no important hemodynamic changes in the pregnant ewe and fetus. There were no significant differences in the fetal serum and tissue levels of the drugs.

Synthesis, characterization, and biodistribution of oxo complexes of technetium-99m with biguanide and N1-substituted ligands

We report the synthesis, characterization, and biodistribution of 99mTc-complexes with the bidentate-N,N chelate biguanide (Big) and the N1-substituted ligands dimethyl (DMBig), phenyl (PBig), and phenethyl (PEBig). Dynamic gamma-camera studies with 99mTc-Big and 99mTc-DMSA in rabbits indicated distinct renal and urinary excretion profiles. 99mTc-Big was cleared more quickly than 99mTc-DMSA, and for the same acquisition times, the contrast in whole-body images favored 99mTc-Big. Also, the estimated radiation absorbed doses by kidneys and blood for 99mTc-DMSA were significantly higher than for 99mTc-Big. These preliminary studies show that 99mTc-Big has favourable practical and dosimetric features for renal imaging as an alternative to 99mTc-DMSA.

[Neurofibromatosis associated with moyamoya arteriopathy and fusiform aneurysm: case report]

We report a case of von Recklinghausen's disease associated with multiple intracranial arterial occlusion ("moyamoya-like") and a fusiform aneurysm. A 28 years-old man with type I neurofibromatosis presented with syncope, complex partial seizures and mental deterioration. After an acute headache episode associated with meningeal signs, drowsiness, and hemorrhagic CSF, the patient was evaluated with cranial CT scan, MRI and angiogram that revealed an obstructive arteriopathy compatible with moyamoya disease and a fusiform aneurysm in the posterior circulation. The authors discuss the clinical and radiological findings and the therapeutic decision in this case comparing with the few similar reports in the medical literature. Recognition of an underlying rare genetic disorder may be of considerable importance in young patients presenting with seizures.

Cardiac lymphatic dynamics after ischemia and reperfusion--experimental model

ABSTRACT. The aim of the present study was to investigate the lymphatic cardiac circulation in an experimental model of ischemia plus reperfusion in mongrel dogs (Canis familiaris L). As radiotracer we used 0.2-0.25 ml (111 MBq) of 99mTc-Re2S7 colloid (+/-10 microm), injected subcapsullary below the second diagonal of the descending anterior ligated coronary artery with a special needle. A gamma-camera/Starport + DecStation were used for data acquisition. Four experimental groups with five animals each were established: G I = controls; G II = immediately after acute myocardial infarction (AMI); G III = late infarction (5 days after AMI); G IV = ischemia (90 min) + reperfusion. Four regions of interest (ROIs) were chosen: injection area (ZA), above (ZB), near right (ZD), and far right (ZC) from ZA. Mean disappearance times in ZA and dynamic parameters in the other ROIs were determined from activity/time curves drawn in each area, using homemade software. The results obtained seem to indicate that the methodology is appropriate to a detailed study of lymphatic drainage in pathological situations in animal models.

An improved mouth-piece to prevent environmental contamination during radioaerosol inhalation procedures

The literature suggests that environmental contamination is common during labeled aerosol inhalation procedures in nuclear medicine. We have tested an adherent mask to prevent environmental contamination in 70 procedures. Two groups of patients were evaluated. Group 1 (60 inhalation cases in which the mask was used) presented no environmental contamination in 95% of the procedures (means of 553 dpm and 596 dpm before and after inhalation, p > 0.05, mean of the differences before/after inhalation 6.95, SD = 21.2 dpm) and the only 3 cases in which contamination did occur concerned bearded men; Group 2 (10 inhalation cases in which the mask was not used) showed large increases of environmental radioactive levels in 70% of the procedures (means of 601 dpm and 2,756 dpm before and after inhalation, p < 0.05, mean of the differences 3,066, SD = 2,98 dpm). We conclude that such a mask is very helpful in avoiding environmental contamination during radioaerosol inhalation procedures.

The effects of maternal position during induction of combined spinal-epidural anesthesia for cesarean delivery

Combined spinal-epidural anesthesia (CSE) is a popular technique for cesarean delivery. Regional blocks in obstetrics are often performed with the parturient in the sitting position because the midline may be recognized more easily than in the lateral decubitus position. When conventional spinal anesthesia is performed in the sitting position, the patient is placed supine immediately after drug injection. In contrast, when CSE is performed with the woman sitting, there is a delay in assuming the supine position because of epidural catheter placement, which may affect the incidence of hypotension. Healthy women, at term of pregnancy, about to undergo an elective cesarean section under CSE, were randomly assigned to the sitting or lateral recumbent position for initiation of the block. All parturients were given 1000 mL of lactated Ringer's solution in the 15 min preceding induction and an additional 300-500 mL while the actual block was being performed. On completion of the CSE, they were turned to the supine position with left uterine displacement. A second anesthesiologist, blinded to the woman's position during CSE, evaluated the sensory level of anesthesia, maternal heart rate, blood pressure, oxygen saturation, need for ephedrine, and occurrence of nausea and vomiting. Results are expressed as mean +/- SD. Twelve women were studied in the sitting group and 10 were studied in the lateral recumbent group. The severity and duration of hypotension were greater in those parturients who had CSE induced in the sitting (47%+/-7% and 6+/-3 min, respectively) compared with the lateral recumbent position (32%+/-14% and 3+/-2 min, respectively). Women in the sitting group also required twice as much ephedrine (38+/-18 mg) to correct hypotension compared with the other group (17+/-12 mg). In conclusion, the severity and duration of hypotension were greater when CSE was induced in the sitting compared with the lateral decubitus position.

IMPLICATIONS

We studied the induction of combined spinal-epidural anesthesia (CSE) in the sitting versus lateral recumbent positions in healthy women undergoing a scheduled cesarean delivery. The severity and duration of hypotension were greater when CSE was induced in the sitting position. Thus, the position used for induction of CSE should be among the factors considered when there is greater maternal or fetal risk from hypotension.

Influence of nonsteroidal anti-inflammatory drugs on calcium efflux in isolated rat renal cortex mitochondria and aspects of the mechanisms involved

In the present study we investigated the influence of several nonsteroidal anti-inflammatory drugs on calcium efflux in isolated rat renal cortex mitochondria in order to assess their potential to disrupt cell calcium homeostasis, as well as aspects of the mechanisms associated with oxidation of mitochondrial pyridine nucleotides (NAD(P)H) and with inhibition of the process by cyclosporin A (CsA). Calcium efflux was estimated with arsenazo III as an indicator and the redox state of NAD(P)H was monitored fluorimetrically at the 366/450 nm excitation/emission wavelength pair. Dipyrone, paracetamol and ibuprofen did not induce calcium efflux even at 1 mM, piroxicam and salicylate were poor inducers, while diclofenac sodium and mefenamic acid were potent inducers releasing calcium even at 20 microM and 10 microM, respectively. In the presence of 10 microM calcium, CsA had no appreciable effect while in the presence of 30 microM calcium it delayed calcium efflux. Oxidation of mitochondrial NAD(P)H, concomitant with calcium efflux and inhibited by CsA, was observed only in the presence of 30 microM calcium. The results suggest that diclofenac sodium and mefenamic acid induce calcium efflux in mitochondria through both a mechanism intrinsic to the mitochondrial membrane permeability transition and a mechanism including the electroneutral Ca2+/nH+ porter.

The effects of epidural analgesia on the course and outcome of labour

The potential effects of epidural analgesia on the progress and outcome of labour have been the subject of lasting controversy. Retrospective reviews indicate that epidurals are associated with longer labours and/or an increase in the incidence of instrumental or operative delivery. Similar results were obtained in non-randomized prospective studies. None of them established a causal relationship, because without randomization the selection bias cannot be ruled out. Other factors, such as premature rupture of membranes and maternal socioeconomic status, may affect the outcome of labour. It was also reported that introduction of the on-demand epidural service did not increase the primary caesarean section rate. The few prospective randomized studies are contradictory and not very reliable owing to small patient populations and high cross-over rates. There is, however, unanimity among the authors regarding the superiority of pain relief provided by epidural blocks over systemically administered opioids.

New amide local anaesthetics for obstetric use

For a number of reasons, bupivacaine has become the most frequently used local anaesthetic in obstetric anaesthesia, despite the fact that it has a narrower margin of safety than other local anaesthetics. In recent years, advances in technology have made single-isomer formulations of drugs available for clinical use. Generally speaking, the levo stereoisomer of amide local anaesthetic has a lower potential for systemic toxicity than the dextro form of the drug while retaining anaesthetic potency. Ropivacaine (Naropin, Astra Ltd), a homologue of mepivacaine and bupivacaine, has recently been released for use. Its clinical efficacy appears to be quite similar to that of bupivacaine but it has a greater margin of safety. The other drug currently being investigated is levobupivacaine (Chirocaine, Chiroscience Ltd). Both drugs appear to be similar in efficacy to the currently used formulation of bupivacaine; however, they are more costly. Thus, cost-benefit analyses are required to define more clearly their future role in obstetric anaesthesia.

Identification of a new WT1 mutation in a sporadic Wilms' tumour

A new mutation in WT1 is described in a sporadic unilateral Wilms' tumour consisting of a 17 bp duplication in exon 7 generating a stop codon. The second allele is either partially deleted or presents the same alteration. LOH analysis at 11p15.5 and at the 16q13-16q24.3 regions indicated retention of heterozygosity in the tumour DNA for the markers analysed. The results are consistent with Knudson's hypothesis and confirm that loss of function of WT1 contributes to the development of at least some Wilms' tumours.

Calcium-induced quenching of intrinsic fluorescence in brain myosin V is linked to dissociation of calmodulin light chains

Myosin V isolated from chick brain (BM V) is a multimeric protein of about 640 kDa consisting of two intertwined heavy chains of 212 kDa and multiple light chains of 10 to 20 kDa. A distinctive feature of the heavy chain is an extended neck region with six consensus IQ sites for the binding of calmodulin (CaM) and myosin light chains. The actin-activated MgATPase has been shown to require >/=1 microM Ca2+ for full activity, and evidence points to a myosin-linked regulatory system where the CaM light chains participate as modulators for the Ca2+ signal. Still, the precise mechanism of Ca2+ regulation remains unknown. In the present study we have used the intrinsic tryptophan fluorescence of native BM V to monitor conformational changes of BM V induced by Ca2+, and we relate these changes to CaM dissociation from the BM V molecule. The fluorescence intensity decreases approximately 17% upon addition of sub-micromolar concentrations of Ca2+ (K0.5 = 0.038 microM). This decrease in fluorescence, which is dominated by a conformational change in the heavy chain, can be reversed by addition of 1, 2-di(2-aminoethoxy)ethane-N,N,N',N'tetraacetic acid (EGTA) followed by an excess of CaM, but not by addition of EGTA alone. Gel filtration of native BM V using HPLC shows that CaM is partially dissociated from the heavy chain in EGTA and dissociates further upon addition of sub-micromolar concentrations of Ca2+. These observations suggest that the affinity of CaM for at least one of the IQ sites on the BM V heavy chain decreases with Ca2+ and that the Ca2+ concentration required for this effect is lower than that needed to activate acto-BM V. Using a cosedimentation assay in the presence of actin, we also observe partial dissociation of CaM when Ca2+ is absent, but now the addition of Ca2+ has a biphasic effect: sub-micromolar Ca2+ concentrations lead to reassociation of CaM with the heavy chain, followed by dissociation when Ca2+ exceeds 5-10 microM. Thus, the binding of CaM to BM V is affected by both actin and Ca2+.

Effect of naturally occurring flavonoids on lipid peroxidation and membrane permeability transition in mitochondria

The ability of eight structurally related naturally occurring flavonoids in inhibiting lipid peroxidation and mitochondrial membrane permeability transition (MMPT), as well as respiration and protein sulfhydryl oxidation in rat liver mitochondria, was evaluated. The flavonoids tested exhibited the following order of potency to inhibit ADP/ Fe(II)-induced lipid peroxidation, estimated with the thiobarbituric acid assay: 3'-O-methyl-quercetin > quercetin > 3,5,7,3',4'-penta-O-methyl-quercetin > 3,7,3',4'-tetra-O-methyl-quercetin > pinobanksin > 7-O-methyl-pinocembrin > pinocembrin > 3-O-acyl-pinobanksin. MMPT was estimated by the extent of mitochondrial swelling induced by 10 microM CaCl2 plus 1.5 mM inorganic phosphate or 30 microM mefenamic acid. The most potent inhibitors of MMPT were quercetin, 7-O-methyl-pinocembrin, pinocembrin, and 3,5,7,3',4'-penta-O-methyl-quercetin. The first two inhibited in parallel the oxidation of mitochondrial protein sulfhydryl involved in the MMPT mechanism. The most potent inhibitors of mitochondrial respiration were 7-O-methyl-pinocembrin, quercetin, and 3'-O-methyl-quercetin while the most potent uncouplers were pinocembrin and 3-O-acyl-pinobanksin. In contrast 3,7,3',4'-tetra-O-methyl-quercetin and 3,5,7,3',4'-penta-O-methyl-quercetin showed the lowest ability to affect mitochondrial respiration. We conclude that, in general, the flavonoids tested are able to inhibit lipid peroxidation on the mitochondrial membrane and/or MMPT. Multiple methylation of the hydroxyl substitutions, in addition to sustaining good anti-lipoperoxidant activity, reduces the effect of flavonoids on mitochondrial respiration, and therefore, increases the pharmacological potential of these compounds against pathological processes related to oxidative stress.

The effects of bupivacaine, L-nitro-L-arginine-methyl ester, and phenylephrine on cardiovascular adaptations to asphyxia in the preterm fetal lamb

The preterm fetal lamb that is exposed to clinically relevant plasma concentrations of lidocaine loses its cardiovascular adaptations to asphyxia, and its condition deteriorates further. Nitric oxide (NO) is an important regulator of vascular tone, and local anesthetics are known to inhibit endothelium-dependent vasodilation. The purpose of the present study was to determine whether the adverse effects of lidocaine noted in the preterm fetal lamb also occur with bupivacaine and whether the inhibition of NO results in effects similar to those of bupivacaine. Thirty-two chronically prepared pregnant sheep were studied at 117-119 days' gestation. Maternal and fetal blood pressure, heart rate, and acid-base state were evaluated. Fetal organ blood flows were determined using 15-microM diameter dye-labeled microspheres. After a control period, mild to moderate asphyxia (fetal PaO2 15 mm Hg) was induced by partial umbilical cord occlusion and maintained throughout the experiment. Ewes in Group I (n = 13) were given a two-step intravenous infusion of bupivacaine for 180 min. Fetuses in Group II (n = 12) received an intravenous injection of L-nitro-L-arginine-methyl ester (L-NAME) (25 mg/kg), and measurements were taken 10 and 30 min after the injection. A third group (Group III) of fetuses (n = 7) were given an intravenous infusion of phenylephrine to mimic the blood pressure increases noted in L-NAME-treated fetuses. At 90 min of stable asphyxia, there was a significant decrease in fetal PaO2 and pHa and an increase in PaCO2 and mean arterial blood pressure. There was also an increase in blood flow to the adrenals, myocardium, and cerebral cortex, whereas blood flow to the placenta decreased. Administration of bupivacaine during asphyxia did not affect the changes in mean arterial blood pressure and acid-base state but did abolish the increases in blood flows to the myocardium and cerebral cortex. Injection of L-NAME to the asphyxiated fetus resulted in an increase in mean arterial blood pressure above the level noted at 90 min of cord occlusion, and an increase in fetal PaO2 toward control levels. This was accompanied by a reduction in organ blood flows to preasphyxia levels. In asphyxiated Group III fetuses, titration of the phenylephrine infusion to achieve blood pressure increases similar to those noted with L-NAME were also associated with an increase in fetal PaO2. These data indicate that bupivacaine abolishes some of the circulatory adaptations to mild to moderate asphyxia induced by partial cord occlusion in the preterm fetal lamb. It is not clear whether these effects of bupivacaine are due to inhibition of NO.

IMPLICATIONS

In the preterm fetal lamb, clinically relevant plasma concentrations of bupivacaine achieved by intravenous infusion to the pregnant ewe (80% gestation) abolished some of the fetal cardiovascular adaptations to asphyxia induced by partial umbilical cord occlusion.

Hg(II)-induced renal cytotoxicity: in vitro and in vivo implications for the bioenergetic and oxidative status of mitochondria

The effects of Hg(II) on bioenergetic and oxidative status of rat renal cortex mitochondria were evaluated both in vitro, and in vivo 1 and 24 h after treatment of animals with 5 mg HgCl2/kg i.p. The parameters assessed were mitochondrial respiration, ATP synthesis and hydrolysis, glutathione content, lipid peroxidation, protein oxidation, and activity of antioxidant enzymes. At low concentration (5 microM) and during a short incubation time, Hg(II) uncoupled oxidative phosphorylation while at slightly higher concentration or longer incubation time the ion impaired the respiratory chain. The rate of ATP synthesis and the phosphorylation potential of mitochondria were depressed, although inhibition of ATP synthesis did not exceed 50%. In vivo, respiration and ATP synthesis were not affected 1 h post-treatment, but were markedly depressed 24 h later. ATP hydrolysis by submitochondrial particle FoF1-ATPase was inhibited (also by no more than 50%) both in vitro, and in vivo 1 and 24 h post-treatment. Hg(II) induced maximum ATPase inhibition at about 1 microM concentration but did not have a strong inhibitory effect in the presence of Triton X-100. Oxidative stress was not observed in mitochondria 1 h post-treatment. However, 24 h later Hg(II) reduced the GSH/GSSG ratio and increased mitochondrial lipid peroxidation and protein oxidation, as well as inhibited GSH-peroxidase and GSSG-reductase activities. These results suggest that the following sequence of events may be involved in Hg(II) toxicity in the kidney: (1) inhibition of FoF1-ATPase, (2) uncoupling of oxidative phosphorylation, (3) oxidative stress-associated impairment of the respiratory chain, and (4) inhibition of ATP synthesis.

Cerebello-trigeminal-dermal dysplasia (Gómez-López-Hernández syndrome): description of three new cases and review

Cerebello-trigemino-dermal "dysplasia" is a rare neurocutaneous syndrome of craniosynostosis, ataxia, trigeminal anesthesia, scalp alopecia, cerebellar anomaly, midface hypoplasia, corneal opacities, apparently low-set ears, mental retardation, and short stature. It seems to be a sporadic condition but little is known about its cause and pathogenesis in the few cases reported so far. We present three new unrelated patients and magnetic resonance images of the central nervous system, and review the four cases reported previously. We think that this is not such a rare condition, and that it is underdiagnosed.

Comparative pharmacokinetics of ropivacaine and bupivacaine in nonpregnant and pregnant ewes

We determined the pharmacokinetics and protein binding of ropivacaine and bupivacaine after intravenous administration to nonpregnant and pregnant sheep. All animals were in good condition throughout the study. The highest mean total serum drug concentrations were found at the end of infusion. For both drugs, pregnancy was associated with lower volumes of distribution during the terminal phase of drug elimination (V(d)beta) and steady state (V(d)ss), as well as with a lower total body clearance (CL). The relationship between V(d)beta and CL was such that the elimination half-life (T(1/2)beta) was not altered. There were also differences between the two drugs. In all animals, the distribution half-life (T(1/2)alpha), T(1/2)beta, volume of central compartment (V(c)), V(d)beta, V(d)ss, and mean residence times (MRT) were greater and CL lower for bupivacaine than ropivacaine. For both drugs, protein binding was concentration-dependent and greater in pregnant ewes. In conclusion, the pharmacokinetics of ropivacaine and bupivacaine are altered by ovine pregnancy in a similar way. If these data are applicable to humans, an unintended intravascular injection of either drug could be expected to result in higher total serum concentrations in the pregnant than in the nonpregnant patient, but drug levels would decline at similar rates in both groups of individuals. However, differences between the two drugs, particularly in T(1/2)beta and MRT, may make ropivacaine preferable for use in obstetric anesthesia.

Diclofenac sodium and mefenamic acid: potent inducers of the membrane permeability transition in renal cortex mitochondria

The ability of nonsteroidal anti-inflammatory drugs (NSAIDs) to induce Ca(2+)-mediated/cyclosporin A-sensitive mitochondrial membrane permeability transition (MMPT) was evaluated by monitoring swelling of isolated rat renal cortex mitochondria in the presence of 20 microM CaCl2. Dipyrone and paracetamol did not induce MMPT, while piroxicam and acetylsalicylic acid (and its metabolite salicylate) were poor inducers. In contrast, diclofenac sodium and mefenamic acid were potent triggering agents, inducing MMPT at 2 microM, a concentration below those previously shown to uncouple and/or inhibit oxidative phosphorylation. When compared to salicylate, a classical uncoupler and inducer of MMPT, the potency of diclofenac sodium and mefenamic acid was about 50-fold greater. Swelling was completely prevented by EGTA, cyclosporin A, or MgCl2, and only partially by ADP or dithiothreitol. Under the same experimental conditions as for the swelling assays, the drugs depressed the membrane potential of mitochondria, an effect prevented by cyclosporin A and restored by EGTA. Also, the drugs did not induce membrane lipid peroxidation or changes in GSSG levels, but led to a small decrease in protein thiol content, as well as to a substantial decrease in the NADPH levels of mitochondria. Hence, membrane depolarization and pyridine nucleotide oxidation seem to be involved in MMPT induction by these NSAIDs. The potency in eliciting the process, like the uncoupling activity, seems to be influenced by the lipophilic character of the molecules.

Neutralization of bothropic and crotalic venom toxic activities by IgG(T) and IgGa subclasses isolated from immune horse serum

IgG(T) and IgGa isotypes were isolated from horse hyperimmune anti-bothropic and anti-crotalic sera using a combination of two affinity chromatographic processes. IgG(T) and IgGa isotypes were isolated from these sera by chromatography on protein A-Sepharose followed by separation of the two isotypes by chromatography on a column of anti-IgG(T)-Sepharose. LO-HoGT-1, a rat anti-horse IgG(T) monoclonal antibody, was used. A comparative study of the efficiency of these isotypes in neutralizing the main toxic activities of the homologous venoms was carried out. It was found that IgG(T) was about three-fold and seven-fold more protective than IgGa for neutralization of the lethal activity of B. jararaca and C. d. terrificus venoms, respectively. IgG(T) was also more effective than IgGa for the neutralization of the haemorrhagic activity induced by B. jararaca venom, while both isotypes neutralized equally well the blood incoagulability induced by this venom. The results suggest that IgG(T) is the most protective isotype present in both anti-bothropic and anti-crotalic sera, followed by IgGa. Owing to their very low concentration in the serum, other IgG isotypes are not likely to be important in neutralizing the venoms' toxic activities.

Synthesis and in vivo antitumor activity of new heterocyclic derivatives of the 1,3,4-thiadiazolium-2-aminide class

Four new mesoionic compounds derivates of 4-phenyl-5-(4-X-cinnamoyl)-1,3,4-thiadiazolium-2-phenylamine chlorides were synthesized and their antitumor activities against Ehrlich carcinoma and Sarcoma 180 (S180) were evaluated. In the schedule assayed, the derivates where X = OH and X = NO2 injected i.p. in mice at a total dose level of 10 and 30 mg/kg respectively caused a significant inhibition of ascitic S180 growth, and at a dose of 25 mg/kg inhibited the growth of Ehrlich carcinoma. The derivates where X = H and X = OCH3 did not show activity. There are no significant changes of hematopoietic parameters of the derivatives in this treatment. These data suggest that the presence of more polar substituents, NO2 and OH, strongly increases the antitumor activity of this class of compounds.

[Cerebral infarctions in young patients related to deficiency of natural anticoagulants. Protein C and protein S]

The possible etiologies of cerebral infarcts (CI) in young patients differ from those in the older stroke population. Recently, deficiencies of fibrinolytic factors emerged as an important etiology of stroke in the young population. The literature has emphasized the diagnosis of such conditions especially in stroke cases of undetermined etiology and with history of recurrent thrombosis. We carried out a research on the serum level of protein C, protein S, and antithrombin III in young patients, between 15 and 40 years, with CI of undetermined cause after application of a standard protocol. Three patients had low levels of these proteins; two had protein C deficiency, and one protein S deficiency. None of them had antithrombin III deficiency. We conclude that systematic investigation of such causes of cerebral infarct will reduce the group of undetermined strokes, and will open the possibility of prophylactic treatment in a non-negligible group of patients.

[Antiphospholipid antibodies in 66 patients with cerebral infarction between 15 and 40 years old]

The antiphospholipid antibodies (aPLs) are a heterogeneous group of immunoglobulins that have been related with alterations in blood coagulability in recent years. Patients with elevated titers of these antibodies have a high probability to develop thrombotic events, including cerebral infarct (CI). The tests currently used to detect these antibodies are the lupus anticoagulant and ELISA for anticardiolipin antibodies which have a larger proportion of positivity among young patients with CI. In our study we tested 66 patients with cerebral infarcts whose ages ranged from 15 to 40 years for the presence of lupus anticoagulant and anticardiolipin antibodies. The results showed that eleven (16.65%) patients were positive for aPLs and three (4.55%) of them fulfilled the diagnostic criteria for primary antiphospholipid syndrome. These data point out to the importance of investigating aPLs in young patients with CI and its high prevalence in this group compared with healthy population.

[Cerebral vasculopathy in the primary antiphospholipid antibody syndrome. Report of 2 cases]

The antiphospholipid antibodies are associated with a large number of neurologic syndromes, cerebral infarct (CI) being the most common of them. In these cases the pathogenesis of the CI is poorly understood and remains controversial; however, the existence of a vasculopathy is indubitable. We report the cases of two young patients with CI and diagnosis of primary antiphospholipid syndrome who were submitted to cerebral angiograms, and one of them to necropsy. In one case the angiographic findings were similar to those of vasculitis in intracranial vessels. In the other case we observed obstruction in internal carotid artery at the angiography that looked like thrombosis in situ; at necropsy we found non-atherosclerotic obstruction in coronary arteries. In summary, is the primary lesion vasculitis, thrombosis, or both? These cases illustrate the discussion and demonstrate that vasculitic mechanisms may be involved in the vasculopathy of primary antiphospholipid syndrome even though thrombosis occur more frequently.

Cerebral infarction in patients aged 15 to 40 years

BACKGROUND AND PURPOSE

Cerebral infarction among young adults has been little studied in Brazil. Most studies adopt a variable upper age limit and often use the term "young" to designate different age ranges. The objective of the present study was to determine possible differences in etiology of cerebral infarction in specific age subpopulations.

METHODS

We studied 106 patients aged 15 to 40 years and divided them into two subpopulations by age at time of ictus (ie, 15 to 29 years and 30 to 40 years). On the basis of Trial of ORG 10172 in Acute Stroke Treatment (TOAST) criteria, we classified the patients into the following five groups: (1) large-artery atherosclerosis, (2) small-vessel occlusion or lacunae, (3) cardioembolism, (4) other determined causes, and (5) undetermined causes. The proportions for each group were compared between the two age ranges to determine whether there was a significant difference in group distribution.

RESULTS

The proportions were different between the two age ranges, with a predominance of women and TOAST-criterion group 4 in the 15- to 29-year age range. In the 30- to 40-year age range, there was a predominance of men and of TOAST-criterion group 3.

CONCLUSIONS

The proportions of the groups in the two age ranges were significantly different for lacunar infarctions and infarctions of other etiologies. This observation suggests that different age ranges present characteristically different distributions and therefore should be considered separately when investigated. The older age range already presents features that suggest a transition to the spectrum observed among the aged.

In vitro interaction of nonsteroidal anti-inflammatory drugs on oxidative phosphorylation of rat kidney mitochondria: respiration and ATP synthesis

The in vitro interference of some of most important nonsteroidal anti-inflammatory drugs (NSAIDs) with the respiration of rat kidney (renal cortex) mitochondria and ATP synthesis was evaluated. Acetylsalicylic acid, diclofenac sodium, mefenamic acid, and piroxicam both uncoupled and inhibited oxidative phosphorylation in mitochondria energized with glutamate plus malate or with succinate, while dipyrone only uncoupled and paracetamol only inhibited it. The drug concentrations affecting mitochondrial respiration were in the low to middle micromolar range for diclofenac, mefenamic acid, and piroxicam, and in the low millimolar range for acetylsalicylic acid, dipyrone, and paracetamol. The pattern of inhibition, except for the paracetamol, was similar to that expressed by the respiratory chain inhibitors. NSAIDs also inhibited the rate of ATP synthesis in mitochondria energized with glutamate plus malate, as well as the phosphorylation potential of mitochondria. The IC50 values for rate of ATP synthesis, using 2 mM ADP, were about 0.1 mM for diclofenac sodium and mefenamic acid, 0.7 mM for piroxicam, and in the range of 5-8 mM for acetylsalicylic acid, dipyrone, and paracetamol. The potential for renal energetic cytotoxicity of NSAIDs is discussed considering their ability to interact with the oxidative phosphorylation in rat renal cortex mitochondria. A comparison is made with the interference of salicylate, the main metabolite of acetylsalicylic acid, and a classical uncoupler of oxidative phosphorylation.

Subarachnoid hemorrhage after aneurysm surgery

The surgical treatment of intracranial aneurysms by clipping is recognized as effective and definitive. However some cases that suffered a new subarachnoid hemorrhage (SAH) some time after they were submitted to aneurysm clipping have raised doubts about the concept of "cure" after this treatment. Eleven patients previously submitted to aneurysm clipping who presented a new SAH were analyzed. The time elapsed from surgery to SAH varied from 3 to 10 years. After SAH four patients had a poor outcome. The new episode of SAH occurred due to intrinsic factors of the cerebral vasculature: 1. a weak point of the vessel wall near the previous aneurysm, 2. a weak point of another vessel far from the previous aneurysm, 3. a previous infundibular dilation of the posterior communicating artery; and due to technical problems: 1. aneurysm not identified during the previous treatment, 2. aneurysm deliberately left untreated, 3. persistence of the aneurysm due to inappropriate surgery, 4. persistency of part of the aneurysm neck after clipping and 5. slipping of the clip from the neck of the aneurysm. The measures to prevent new SAH after surgery start with adequate preoperative angiographic studies, a careful inspection of the position of the clip and emptying of the aneurysm. Early angiography studies may reveal a persistent neck and later ones may reveal newly developed aneurysms. In conclusion, SAH after aneurysm clipping is a late and severe phenomenon and the concept of "cure" after this surgery should be interpreted with caution.

Chemical composition and nutritional potential of yam bean seeds (Pachyrhizus erosus L. urban)

Pachyrhizus erosus seeds were analysed for proximate composition, minerals, protein fractions, antinutritional factors, and rotenoids. The seeds showed a high content of proteins, lipids, Fe and Ca, in comparison to other legumes. Glutelins constitute the highest protein fraction, followed by globulins. Antinutritional substances detected as tannins, hemagglutinating activity and trypsin inhibitory activity, were in low concentrations. Seeds were also processed to obtain a flour which showed proper characteristics, good in vitro digestibility, significant rotenoid reduction level and amino acid composition rich in essential amino acids, except methionine.

[Reversible cerebral changes in hemolytic-uremic syndrome]

The hemolytic-uremic syndrome is a pathology characterized by a triad consisting of acute renal failure, microangiopathic hemolytic anemia and thrombocytopenia, with complications of the central nervous system arising in a considerable number of cases. Altered cranial computerized tomography examinations usually reveal cerebral infarctions. We present here two cases in which diffuse hypodensity was observed in the white matter in addition to the infarcts. This hypodensity was reversible after resolution of the acute phase of the disease, as is also the case for the alterations described in uremic encephalopathy and in hypertensive encephalopathy of other etiologies.

Comparative systemic toxicity of ropivacaine and bupivacaine in nonpregnant and pregnant ewes

BACKGROUND

Ropivacaine is a new amide local anesthetic, having therapeutic properties similar to those of bupivacaine but with a wider margin of safety. Bupivacaine is probably the most commonly used drug in obstetric epidural analgesia, even though laboratory studies have suggested that pregnancy increases the cardiotoxicity of bupivacaine but not of other local anesthetics. The current study was designed to reevaluate, in a random and blinded fashion, the systemic toxicity of bupivacaine and ropivacaine in nonpregnant and pregnant sheep.

METHODS

Chronically prepared nonpregnant and pregnant ewes were randomized to receive an intravenous infusion of ropivacaine or bupivacaine at a constant rate of 0.5 mg.kg-1.min-1 until circulatory collapse. The investigators were blinded to the identity of local anesthetic. Heart rate, arterial blood pressure, and cardiac rhythm were monitored throughout the study. Arterial blood samples were obtained before infusion and at the onset of toxic manifestations, which appeared in the following sequence: convulsions, hypotension, apnea, and circulatory collapse. Serum drug concentrations and protein binding were determined. Blood pH and gas tensions were measured.

RESULTS

There were no significant differences between non-pregnant and pregnant animals in the doses or serum concentrations of either drug required to elicit toxic manifestations. In nonpregnant animals, similar doses and serum concentrations of ropivacaine and bupivacaine were associated with the onset of convulsions and circulatory collapse. In pregnant ewes, greater doses of ropivacaine as compared to bupivacaine were required to produce convulsions (7.5 +/- 0.5 vs. 5.0 +/- 0.6 mg.kg-1) and circulatory collapse (12.9 +/- 0.8 vs. 8.5 +/- 1.2 mg.kg-1). The corresponding serum concentrations of ropivacaine were similar to those of bupivacaine. Pregnancy did not affect the serum protein binding of either drug. The proportion of animals manifesting a malignant ventricular arrhythmia as the terminal event was similar among all groups.

CONCLUSIONS

The systemic toxicity of ropivacaine or bupivacaine is not enhanced by gestation in sheep. This is in contrast to an earlier study in which the cardiotoxicity of bupivacaine was enhanced during ovine pregnancy. Greater doses of ropivacaine, as compared to bupivacaine, are needed to produce toxic manifestations in pregnant animals.

Use of the Syrian golden hamster for the induction of intraoral abscesses by sutures contaminated with human subgingival plaque

Analysis of normal oral flora in 150 cheek pouches of hamsters (Mesocricetus auratus) defined the microbial working environment and demonstrated the absence of human oral black-pigmented bacteria. Silk sutures saturated with Porphyromonas gingivalis, Prevotella intermedia or subgingival plaque were used to close wounds made in hamster's cheek pouches. Abscesses were formed when sutures had solitary P. gingivalis or other bacteria mixed with P. gingivalis or when P. intermedia was mixed with other bacteria besides P. gingivalis. A concentration of black-pigmented bacteria emanating from 3 x 10(5) colony-forming units/inoculum was required for abscess formation. Six abscesses (14.3%) were developed in association with the presence of other odontopathic bacteria, primarily Fusobacterium nucleatum and Actinomyces viscosus. The hamster cheek pouch with iatrogenic wounds closed with plaque-impregnated sutures is a novel and effective model to study the pathology of wound infections and virulence of human subgingival organisms.

[Pulmonary lymphangioleiomyomatosis]

The authors present a clinical case of Lymphangioleiomyomatosis of the lung. They analyse the clinical, radiological and functional features and comment on the evolution and therapeutic approach of this rare disorder. To the authors, lung involvement as well as therapeutic decision are important features that affect the prognosis.

Fracture resistance of premolars with MOD amalgam restorations lined with Amalgambond

A comparison was made of the fracture resistance of premolar teeth with mesial-occlusal-distal (MOD) amalgam preparations lined with either a resin containing 4-META (Amalgambond) or copal varnish (Plastodent) and restored with a spherical alloy (Tytin). Restored teeth were aged for 7 or 67 days at 37 degrees C in 100% humidity and thermocycled between 5 and 55 degrees C for 3500 cycles. There was no significant difference in the mean fracture resistance between teeth lined with Amalgambond and teeth lined with Plastodent under any of the test conditions. SEM analysis of thermocycled specimens showed no evidence of maintained adhesion between the Amalgambond and amalgam.

The maternal and fetal effects of milrinone and dopamine in normotensive pregnant ewes

The safety of milrinone, administered during gestation, was evaluated in seven chronically instrumented pregnant ewes and their fetuses. Each of the following six intravenous regimens was administered in random order: milrinone, 75 micrograms.kg-1, over 1 minute, followed by 240-minute infusions of the drug at a rate of 1, 2, or 4 micrograms.kg-1.min-1; dopamine 5 or 10 micrograms.kg-1.min-1 over 60 minutes; or normal saline solution, 0.5 ml.min-1 for 240 minutes. Maternal and fetal acid-base parameters, heart rate, and blood pressure were monitored as were the ewe's venous and intraamniotic pressures and uterine blood flow. Milrinone concentrations determined in maternal arterial blood samples obtained during 1 and 2 micrograms.kg-1.min-1 infusions were found to be within the human therapeutic range. Bolus injection of milrinone, as well as the lowest drug infusion, resulted in no significant changes in uterine blood flow, whereas 2 micrograms.kg-1.min-1 milrinone infusion led to a 14% to 19% increase in uterine blood flow between 120 and 240 minutes. With the highest milrinone infusion, this increase was approximately 20%. In contrast, with both dopamine infusions, a dose-related decrease in uterine blood flow of 15% to 26% occurred between 15 and 60 minutes. No milrinone could be detected in any fetal plasma samples. Fetal arterial pH and blood gas tensions did not change during milrinone infusions. Dopamine 10 micrograms.kg-1.min-1 led to a progressive decrease in fetal arterial pH and an increase in PaCO2, which may have been related to similar changes in the ewe. It is concluded that milrinone has no adverse effects on uterine blood flow and fetal well-being when administered during ovine pregnancy.

Effect of ropivacaine and bupivacaine on uterine blood flow in pregnant ewes

The effects of ropivacaine, a new amide local anesthetic, on uterine blood flow and fetal well-being were compared with those of bupivacaine in 10 chronically instrumented pregnant ewes. In random sequence, animals received two intravenous infusions of each drug. The low infusion rate regimens were chosen to result in clinically relevant maternal plasma concentrations of local anesthetics, whereas the more rapid rates of infusions were given to assess the safety of higher maternal drug concentrations. An epinephrine infusion was given to demonstrate the appropriateness of the animal model for the measurement of uterine blood flow. Maternal and fetal heart rates, arterial blood pressure, and the ewe's central venous pressure, intraamniotic pressure, and uterine blood flow were recorded continuously. Arterial blood samples were taken from mother and fetus at frequent intervals to determine acid-base status and local anesthetic concentrations. A total of 39 studies were performed. None of the infusions of either local anesthetic resulted in a significant decrease in uterine blood flow or deterioration in fetal condition. The mean maternal plasma concentrations at the end of infusions were as follows: ropivacaine low dose, 1.60 +/- 0.35 micrograms/mL; bupivacaine low dose, 1.55 +/- 0.15 micrograms/mL; ropivacaine high dose, 2.50 +/- 0.37 micrograms/mL; and bupivacaine high dose, 1.83 +/- 0.19 micrograms/mL. Epinephrine infusion resulted in a 25% decrease in uterine blood flow without adverse fetal effects. We conclude that neither ropivacaine nor bupivacaine, as administered in this study, led to any ill effects on uterine artery blood flow or fetal well-being.

Systemic toxicity of ropivacaine during ovine pregnancy

Ropivacaine is a new amide local anesthetic structurally related to bupivacaine and mepivacaine. Its potency and duration of action are similar to those of bupivacaine but its therapeutic index may be greater. Since pregnancy enhances the cardiotoxicity of bupivacaine, the current study was devised to compare the toxicity of ropivacaine in chronically instrumented nonpregnant and pregnant ewes during continuous intravenous infusion of the drug at the rate of 0.5 mg.kg-1.min-1. In all animals, symptoms of local anesthetic toxicity occurred in the usual order--convulsions, hypotension, apnea, and circulatory collapse. There were no significant differences between the two groups of animals in the doses and plasma concentrations of ropivacaine associated with each toxic manifestations. For example, circulatory collapse occurred at a mean dose of 11.3 +/- 1.1 mg.kg-1 in nonpregnant and 12.4 +/- 0.9 mg.kg-1 in pregnant animals, with corresponding plasma concentrations of 7.3 +/- 0.3 and 9.6 +/- 2.1 micrograms.ml-1 (P = not significant). Protein binding of ropivacaine in the concentration range associated with toxic manifestations was similar in sera obtained from nonpregnant and pregnant ewes. In conclusion, ovine pregnancy does not enhance the systemic toxicity of ropivacaine, possibly because of an absence of gestation-related increase in the availability of free drug.