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.

A new derivatization procedure for the analysis of hippuric acid and m-methyl-hippuric acid by gas chromatography

The industrial solvents, toluene and xylene, have physicochemical properties that can be hazardous to the workers exposed. Since hippuric acid and m-methyl-hippuric acid represent the products of toluene and xylene biotransformation in urine, they are used as biological markers in studies on occupational exposure to these solvents. Several methods have been used to determine hippuric acid and m-methyl-hippuric acid--either based on gas chromatography or on high-performance liquid chromatography. In this study we propose the derivatization of hippuric acid and methyl-hippuric acid using methanol in acid medium (HCl), a low-cost reagent with a low level of toxicity. The method has been routinely used in our laboratory for 1 year and has proven to be a reliable procedure for the biological control of occupational exposure to toluene and/or xylene.

Pharmacokinetics of ropivacaine in nonpregnant and pregnant ewes

The pharmacokinetics of ropivacaine were studied in chronically instrumented nonpregnant and pregnant ewes. On the day of study, the urinary bladder was catheterized. Ropivacaine (2.5 or 3.0 mg/kg) was administered by intravenous infusion over 2 or 4 min. Serial samples of arterial blood and urine were collected over 5 h, and drug concentrations were determined using a gas chromatographic technique. Total clearance of ropivacaine was lower in the pregnant animals (21.6 +/- 4.5 mL.min-1.kg-1) compared with the nonpregnant animals (45.1 +/- 6.7 mL.min-1.kg-1). There was a tendency toward a decrease in the volume of distribution during the terminal exponential phase of drug elimination of 2.03 +/- 0.36 L/kg in the pregnant and 4.32 +/- 1.03 L/kg in the nonpregnant sheep. Thus the difference in the elimination half-life was only minimal: 74.7 +/- 10.7 min in the pregnant and 64.4 +/- 7.4 min in the nonpregnant animals. It is concluded that ovine pregnancy is accompanied by changes in the pharmacokinetics of ropivacaine. Inadvertent intravenous injections of similar drug doses to pregnant and nonpregnant women might result in higher plasma concentrations of ropivacaine in the former. However, the rate of decline in plasma levels of the drug would be similar in both.

Incidence of visceral pain during cesarean section: the effect of varying doses of spinal bupivacaine

The safety of 0.5% hyperbaric bupivacaine, as well as the incidence and severity of visceral pain, were evaluated in 36 women undergoing elective cesarean section under spinal anesthesia who, randomly divided into two groups, received different dose ranges according to height, 7.5-10 mg in group A and 10-12.5 mg in group B. When sensory block to at least the fourth thoracic dermatome was established, surgery was begun and the occurrence and severity of visceral pain recorded (visual analog scale) by an observer unaware of patient data. The level of analgesia to pinprick was determined when and if there was onset of pain intraoperatively, and supplementary medication was administered as needed. Hypotension, the incidence of which was similar in both groups, was treated as necessary with ephedrine. No patients experienced pain until after delivery of the infant. Thereafter, moderate to severe pain, in association with peritoneal traction, occurred in 12 patients in group A (70.5%) but only in 6 patients in group B (31.6%). In patients experiencing moderate to severe pain, the mean time between induction of anesthesia and onset of pain was similar in both groups, as was the amount of systemic narcotic given. Total time for regression of sensory analgesia to L5 was longer in patients in group B (243.9 versus 195.4 min), and the incidence of complete motor blockade was greater in group B. Increasing the amount of 0.5% hyperbaric bupivacaine per spinal segment reduces the occurrence of moderate to severe visceral pain during elective cesarean section without jeopardizing mother or fetus.

Adverse effects of maternally administered lidocaine on the asphyxiated preterm fetal lamb

Lidocaine was infused at a constant rate of 0.1 mg.kg-1.min-1 for 180 min into 12 chronically prepared pregnant sheep while asphyxia, induced by partial umbilical cord occlusion, was maintained in the premature fetus (80% of gestation). In five similar preparations saline instead of lidocaine was infused into the mother for 180 min. Maternal and fetal arterial blood pressure, heart rate, pHa, PaCO2, and PaO2 were monitored, and fetal cardiac output and the distribution of blood flow to fetal organs were measured, using labeled microspheres, before and after asphyxia and again after maternal infusion of lidocaine or saline. Maternal and fetal arterial blood and maternal urine were obtained at intervals for determination of lidocaine concentrations and urinary drug clearance. At the end of infusion, these animals were killed and tissues dissected for determination of lidocaine concentrations and organ blood flow. Maternal and fetal lidocaine plasma concentrations at steady state were 2.32 +/- 0.12 and 1.23 +/- 0.17 microgram/ml, respectively, similar to those seen during human epidural anesthesia. Asphyxia resulted in a significant drop in fetal heart rate and increased blood flow to the brain, heart, and adrenals. Asphyxia and saline did not produce additional deterioration of the fetus, but asphyxia and lidocaine led to a significant increase in PaCO2 and decreases in pHa, mean arterial pressure, and blood flows to the brain, heart, and adrenals. It is concluded that the immature fetus loses its cardiovascular adaptation to asphyxia when exposed to clinically acceptable plasma concentrations of lidocaine obtained transplacentally from the mother.

Does pregnancy alter the systemic toxicity of local anesthetics?

The toxicity of mepivacaine in chronically instrumented nonpregnant and pregnant sheep was evaluated, and compared with data from previous studies of the toxicity of other local anesthetics. Thirteen preparations were studied, seven nonpregnant (NP) and six pregnant (P). Mepivacaine 2 mg.kg-1.min-1 was infused at a constant rate into the femoral vein until toxic manifestations occurred, in the following sequence: convulsions, hypotension, respiratory arrest, and circulatory collapse. The doses and plasma concentrations of mepivacaine necessary to produce toxic symptoms were similar in NP and P animals, whereas, in a previous study, pregnancy enhanced the cardiotoxicity of bupivacaine. No malignant ventricular arrhythmias were observed throughout the study. Protein binding of mepivacaine was also determined in sera from nonpregnant and pregnant ewes and compared with that for bupivacaine. Serum protein binding of mepivacaine was not reduced in pregnancy at the drug concentrations associated with toxic symptoms; at circulatory collapse, it was approximately 22% in NP and P. In contrast, the proportion of bound bupivacaine was 73% in NP and 51% in P, a significant difference. These protein binding data suggest that, although lethal concentrations of bupivacaine, determined in the previous study, were higher in NP than in P animals, concentrations of free drug were similar. Thus, the difference between the two drugs may be related to gestational increases in the availability of free drug in the case of bupivacaine.

Pharmacokinetics of lidocaine in nonpregnant and pregnant ewes

The pharmacokinetics of lidocaine were studied in nonpregnant and pregnant ewes. The maternal femoral vessels were cannulated and, on the day of study, the urinary bladder was catheterized. Lidocaine HCl, 4-5 mg/kg, was administered by IV injection over 60 seconds. Serial samples of arterial blood and urine were collected over 4 hours, and drug concentrations were determined using a gas chromatographic technique. The volume of the central compartment was greater in pregnant than in nonpregnant ewes (1.51 +/- 0.20 vs. 0.96 +/- 0.16 L/kg) as was the volume of distribution at steady state (Vdss): 3.24 +/- 0.40 vs. 1.88 +/- 0.32 L/kg. The volume of distribution during the terminal exponential phase of drug elimination (Vd beta) and total clearance of lidocaine (Cl) were also higher in pregnant animals: 4.17 +/- 0.50 L/kg and 99.6 +/- 8.5 ml.min-1.kg-1, respectively; compared to 2.46 +/- 0.48 L/kg and 44.1 +/- 6.5 ml.min-1.kg-1, in nonpregnant ewes. However, the balance between these changes in Vd beta and Cl did not result in a significant difference in the elimination half-life of lidocaine (38.1 +/- 2.1 minutes in nonpregnant and 31.9 +/- 3.0 minutes in pregnant ewes). If these data are applicable to humans, the risk of drug accumulation after repeated administration of lidocaine is no greater in pregnant than in nonpregnant patients.

Does gestational age affect the pharmacokinetics and pharmacodynamics of lidocaine in mother and fetus?

The pharmacokinetics and pharmacodynamics of lidocaine were studied in nine chronically prepared pregnant ewes and their fetuses at a mean ( +/- SE) gestation of 119 +/- 1.0 days, and the results were compared to the data previously published for ten animals at 138 +/- 1.2 days of gestation (term 148 days). Lidocaine was infused intravenously to the mother at a constant rate of 0.1 mg.kg-1.min-1 over a period of 180 min, in order to reach a steady-state maternal plasma lidocaine concentration of approximately 2 micrograms/ml. Maternal and fetal blood samples and maternal urine were collected at intervals throughout the infusion for determination of pH, blood gases, and lidocaine concentrations. Maternal and fetal heart rate, blood pressure, and intraamniotic pressure were continuously recorded. Fetal cardiac output and organ blood flow were determined before and at the end of lidocaine infusion using radionuclide-labeled microspheres. Lidocaine tissue concentrations were determined in several maternal and fetal organs excised at the end of infusion. In both groups, the steady-state plasma concentrations of lidocaine were similar; namely, 2.3 +/- 0.17 and 2.1 +/- 0.21 micrograms/ml in preterm and term ewes, respectively. There were also no significant differences in steady-state plasma drug concentrations in preterm and term fetuses (1.3 +/- 0.11 and 1.2 +/- 0.15 micrograms/ml). The mean fetal maternal concentration ratios (F/M) were the same; namely, 0.6. Maternal urinary excretion of lidocaine correlated with urine pH, being greater in the more acid urine. Tissue uptake of drug tended to be higher in the preterm than term mothers, but only significantly so in the brain and adrenals.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of lidocaine on the asphyxial responses in the mature fetal lamb

The effects of lidocaine on the fetal circulatory responses to asphyxia were evaluated in chronically instrumented pregnant sheep. Twenty-six preparations were studied. Animals were assigned to one of three groups. The animals in group I (N = 10) did not have umbilical cord occluders placed. Lidocaine at 0.1 mg X kg-1 X min-1 was infused to the mother for 180 min. The animals in group II (N = 11) had an umbilical cord occluder, which was inflated to induce fetal asphyxia (PaO2 15 mmHg) for 90 min. Occlusion was then maintained for an additional 180 min while lidocaine at 0.1 mg X kg-1 X min-1 was infused. The animals in group III (N = 5) also had an umbilical cord occluder inflated for 90 min. While occlusion was maintained for an additional 180 min, saline was infused, in place of lidocaine. The infusion rate of lidocaine of 0.1 mg X kg-1 X min-1 over 180 min resulted in a steady-state arterial lidocaine blood concentration in the mother of approximately 2.15 micrograms/ml. Fetal circulatory responses to asphyxia were evaluated before and after maternal infusion of lidocaine or normal saline. Measurements included heart rate, blood pressure, arterial pH, and blood gases. Cardiac output and organ blood flow were determined using the radio-labelled microsphere technique. In general, arterial and tissue lidocaine concentrations in asphyxiated fetuses were higher than those in the nonasphyxiated ones, the differences being significant in the brain, heart, liver, and adrenal glands.(ABSTRACT TRUNCATED AT 250 WORDS)

[Protein concentrate of the manioc leaf. Extraction, chemical analyses and supplementation with amino acids]

The purpose of this work was to prepare a manioc leaf protein concentrate introducing some new procedures on the known methods developed by other authors. Chemical composition and biological quality (PER, Digestibility, NPU and BV) of the protein content were measured for diets prepared with leaf protein concentrate and leaf. Histological studies were carried out in some organs. The protein concentrate and the powdered leaves were supplemented with methionine and lysine, alone and combined. The protein content (N X 6.25) of the concentrate and the leaf was 34% and 25.2%, respectively. Addition of either methionine or lysine alone did not improve the growth of the rats. A better response was obtained when both methionine and lysine supplemented the test materials as indicated by the biological criteria, protein efficiency ratio (PER) true digestibility (TD) and biological value (BV). Histological tests for the organs examined, proved to be normal.

Revised structure of phaeantharine

Revised structure 8 is proposed for the quaternary bisbenzylisoquinoline alkaloid phaeantharine, based on spectrometric data. Phaeantharine, which occurs in Phaeanthus ebracteolatus (fam. Anonaceae), has current interest as a potential insecticide. Phaeantharine also exhibits moderate activity against gram-positive bacteria.

[Assessment of early arrhythmias in acute experimental myocardial infarct in rabbits]

Arrhythmias were studied at the early stage after rapid ligation of the left ventricular artery on an experimental model of arrhythmia in rabbits. The rabbits were subjected to thoractomy and ligation of the left ventricular artery under direct visualization. The electrocardiographic and hemodynamic parameters were recorded. Electrocardiographic signs of infarction and changes in rhythm were recorded in 60% of the animals. The rate of cardiac contractions and the arterial pressure decreased after the ligation. In the group in which practolol was applied the rate of arrhythmias dropped to 25%. The effect of adrenergic beta-block on acute occlusion of the coronary artery is discussed.