Lipschütz Ulcer: An Unusual Diagnosis that Should Not be Neglected.

The diagnosis of genital ulcers remains a challenge in clinical practice. Lipschütz ulcer is a non-sexually transmitted rare and, probably, underdiagnosed condition, characterized by the sudden onset of vulvar edema along with painful necrotic ulcerations. Despite its unknown incidence, this seems to be an uncommon entity, with sparse cases reported in the literature. We report the case of an 11-year-old girl who presented at the emergency department with vulvar ulcers. She denied any sexual intercourse. The investigation excluded sexually transmitted infections, so, knowledge of different etiologies of non-venereal ulcers became essential. The differential diagnoses are extensive and include inflammatory processes, drug reactions, trauma, and malignant tumors. Lipschütz ulcer is a diagnosis of exclusion. With the presentation of this case report, the authors aim to describe the etiology, clinical course, and outcomes of this rare disease, to allow differential diagnosis of genital ulceration.

Lipschütz Ulcer: An Unusual Diagnosis that Should Not be Neglected

Abstract The diagnosis of genital ulcers remains a challenge in clinical practice. Lipschütz ulcer is a non-sexually transmitted rare and, probably, underdiagnosed condition, characterized by the sudden onset of vulvar edema along with painful necrotic ulcerations. Despite its unknown incidence, this seems to be an uncommon entity, with sparse cases reported in the literature. We report the case of an 11-year-old girl who presented at the emergency department with vulvar ulcers. She denied any sexual intercourse. The investigation excluded sexually transmitted infections, so, knowledge of different etiologies of non-venereal ulcers became essential. The differential diagnoses are extensive and include inflammatory processes, drug reactions, trauma, and malignant tumors. Lipschütz ulcer is a diagnosis of exclusion. With the presentation of this case report, the authors aim to describe the etiology, clinical course, and outcomes of this rare disease, to allow differential diagnosis of genital ulceration.

Pre-clinical evaluation of new dibucaine formulations for preventive analgesia.

We have previously developed ammonium sulphate gradient loaded liposomes to encapsulate dibucaine. Thus, the purpose of this study was to evaluate the pre-clinical safety and effectiveness of this novel ionic liposomal formulation of dibucaine (DBC), as described in previous work. Effectiveness was evaluated in vivo on Wistar rats (n = 8) that received plain DBC or liposomal DBC (DBCLUV). Control empty liposomes (without DBC) or saline were also used as control. Sciatic nerve block was performed using the formulations or controls (0.4 mL). A hindpaw incision-based postoperative pain model was used to evaluate mechanical hypersensitivity with von Frey filaments. To verify antiinflamatory activity protein levels of TNF-α, IL-1ß, substance P and CGRP were measured by ELISA in the hindpaw tissue after 1 and 6 hours of the incision. To corroborate drug safety, sciatic nerve Schwann cell cultures were treated with the aforementioned formulations and assessed for cell viability (MTT assay) and death (flow cytometry assay). Histopathology of the tissues surrounding the sciatic nerve region was also assessed 2 and 7 days after treatment. All animals presented post incisional hypersensitivity and DBCLUV showed longer analgesic effect (p < 0.001). DBCLUV reduced TNF-α and CGRP levels (p < 0.05). Histopathological evaluation showed greater inflammatory reaction after the administration of control liposomes when compared to DBC (p < 0.05). There was no difference in Schwann cell viability and death between plain and encapsulated DBC. DBCLUV was safe and enhanced anaesthesia duration due to slow release of dibucaine from ammonium sulphate gradient loaded liposomes.

Electron Paramagnetic Resonance and Small-Angle X-ray Scattering Characterization of Solid Lipid Nanoparticles and Nanostructured Lipid Carriers for Dibucaine Encapsulation.

Dibucaine (DBC) is one of the most potent long-acting local anesthetics, but it also has significant toxic side effects and low water solubility. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) have been proposed as drug-delivery systems to increase the bioavailability of local anesthetics. The purpose of the present study was to characterize SLNs and NLCs composed of cetyl palmitate or myristyl myristate, a mixture of capric and caprylic acids (for NLCs only) plus Pluronic F68 prepared for the encapsulation of DBC. We intended to provide a careful structural characterization of the nanoparticles to identify the relevant architectural parameters that lead to the desirable biological response. Initially, SLNs and NLCs were assessed in terms of their size distribution, morphology, surface charge, and drug loading. Spectroscopic techniques (infrared spectroscopy and electron paramagnetic resonance, EPR) plus small-angle X-ray scattering (SAXS) provided information on the interactions between nanoparticle components and their structural organization. The sizes of nanoparticles were in the 180 nm range with low polydispersity and negative zeta values (-25 to -46 mV). The partition coefficient of DBC between nanoparticles and water at pH 8.2 was very high (>104). EPR (with doxyl-stearate spin labels) data revealed the existence of lamellar arrangements inside the lipid nanoparticles, which was also confirmed by SAXS experiments. Moreover, the addition of DBC increased the molecular packing of both SLN and NLC lipids, indicative of DBC insertion between the lipids, in the milieu assessed by spin labels. Such structural information brings insights into understanding the molecular organization of these versatile drug-delivery systems which have already demonstrated their potential for therapeutic applications in pain control.

Dibucaine in Ionic-Gradient Liposomes: Biophysical, Toxicological, and Activity Characterization.

Administration of local anesthetics is one of the most effective pain control techniques for postoperative analgesia. However, anesthetic agents easily diffuse into the injection site, limiting the time of anesthesia. One approach to prolong analgesia is to entrap local anesthetic agents in nanostructured carriers (e.g., liposomes). Here, we report that using an ammonium sulphate gradient was the best strategy to improve the encapsulation (62.6%) of dibucaine (DBC) into liposomes. Light scattering and nanotracking analyses were used to characterize vesicle properties, such as, size, polydispersity, zeta potentials, and number. In vitro kinetic experiments revealed the sustained release of DBC (50% in 7 h) from the liposomes. In addition, in vitro (3T3 cells in culture) and in vivo (zebrafish) toxicity assays revealed that ionic-gradient liposomes were able to reduce DBC cyto/cardiotoxicity and morphological changes in zebrafish larvae. Moreover, the anesthesia time attained after infiltrative administration in mice was longer with encapsulated DBC (27 h) than that with free DBC (11 h), at 320 µM (0.012%), confirming it as a promising long-acting liposome formulation for parenteral drug administration of DBC.

Postoperative topical analgesia of hemorrhoidectomy with policresulen and cinchocaine: a prospective and controlled study.

OBJECTIVE: To evaluate the effects of topical policresulen and cinchocaine in the postoperative pain behavior of open hemorrhoidectomy. METHODS: We conducted a prospective, double-blinded, controlled study. The control group received the usual guidelines with oral medications. The topical treatment group received, in addition, the application of the ointment and was comprised of two subgroups (policresulen + cinchocaine, and placebo). Pain intensity was recorded with the visual analogue scale. RESULTS: 43 patients were operated on: control group - n = 13, one excluded; placebo - n = 15; and policresulen + cinchocaine - n = 15. The mean age was 45.98 years and 37.2% were men. The average pain intensity was 4.09 (immediate postoperative), 3.22 (hospital discharge), 5.73 (day 1) , 5.77 (day 2), 5.74 (day 3), 5.65 (day 7), 5.11 (day 10), 2.75 (day 15) and 7.70 (first bowel movement), with no difference between groups in all periods. CONCLUSION: This study showed no reduction in pain after hemorrhoidectomy with the use of topical policresulen and cinchocaine.

Postoperative topical analgesia of hemorrhoidectomy with policresulen and cinchocaine: a prospective and controlled study / Analgesia tópica com policresuleno e cinchocaína no pós-operatório de hemorroidectomias: um estudo prospectivo e controlado

OBJECTIVE: To evaluate the effects of topical policresulen and cinchocaine in the postoperative pain behavior of open hemorrhoidectomy. METHODS: We conducted a prospective, double-blinded, controlled study. The control group received the usual guidelines with oral medications. The topical treatment group received, in addition, the application of the ointment and was comprised of two subgroups (policresulen + cinchocaine, and placebo). Pain intensity was recorded with the visual analogue scale. RESULTS: 43 patients were operated on: control group - n = 13, one excluded; placebo - n = 15; and policresulen + cinchocaine - n = 15. The mean age was 45.98 years and 37.2% were men. The average pain intensity was 4.09 (immediate postoperative), 3.22 (hospital discharge), 5.73 (day 1) , 5.77 (day 2), 5.74 (day 3), 5.65 (day 7), 5.11 (day 10), 2.75 (day 15) and 7.70 (first bowel movement), with no difference between groups in all periods. CONCLUSION: This study showed no reduction in pain after hemorrhoidectomy with the use of topical policresulen and cinchocaine. .

OBJETIVO: avaliar a ação do policresuleno e cinchocaína tópicos no comportamento da dor no pós-operatório de hemorroidectomias abertas. MÉTODOS: estudo prospectivo, duplo cego e controlado. O grupo controle recebeu as orientações usuais com medicações de uso oral. O grupo de tratamento tópico recebeu, adicionalmente, a aplicação de pomada e foi composto de dois subgrupos (policresuleno + cinchocaína; e placebo). A intensidade da dor foi registrada a partir da escala visual analógica. RESULTADOS: foram operados 43 pacientes: grupo controle (n=13; um excluído), placebo (n=15) e policresuleno + cinchocaína (n=15). A média de idade foi 45,98 anos e 37,2% foram homens. A média da intensidade da dor foi 4,09 (PO imediato), 3,22 (alta hospitalar), 5,73 (dia 1), 5,77 (dia 2), 5,74 (dia 3), 5,65 (dia 7), 5,11 (dia 10), 2,75 (dia 15) e 7,70 (primeira evacuação), sem diferença entre os grupos em todos os períodos estudados. CONCLUSÃO: este estudo não demonstrou redução da dor após hemorroidectomias como o uso do tratamento tópico. .

Dibucaine effects on structural and elastic properties of lipid bilayers.

In this work we report the interaction effects of the local anesthetic dibucaine (DBC) with lipid patches in model membranes by Atomic Force Microscopy (AFM). Supported lipid bilayers (egg phosphatidylcholine, EPC and dimyristoylphosphatidylcholine, DMPC) were prepared by fusion of unilamellar vesicles on mica and imaged in aqueous media. The AFM images show irregularly distributed and sized EPC patches on mica. On the other hand DMPC formation presents extensive bilayer regions on top of which multibilayer patches are formed. In the presence of DBC we observed a progressive disruption of these patches, but for DMPC bilayers this process occurred more slowly than for EPC. In both cases, phase images show the formation of small structures on the bilayer surface suggesting an effect on the elastic properties of the bilayers when DBC is present. Dynamic surface tension and dilatational surface elasticity measurements of EPC and DMPC monolayers in the presence of DBC by the pendant drop technique were also performed, in order to elucidate these results. The curve of lipid monolayer elasticity versus DBC concentration, for both EPC and DMPC cases, shows a maximum for the surface elasticity modulus at the same concentration where we observed the disruption of the bilayer by AFM. Our results suggest that changes in the local curvature of the bilayer induced by DBC could explain the anesthetic action in membranes.

Effects of dibucaine on the endocytic/exocytic pathways in Trypanosoma cruzi.

Although local anesthetics (LA) are considered primarily Na+-channel blockers in the past decade, an alternative action of LA as inhibitors of fusion among compartments of the endocytic/exocytic pathways was described. In epimastigote forms of Trypanosoma cruzi, we observed that 50 mM dibucaine reduced the rates of uptake of bovine serum albumin (BSA) and immunoglobulin to 60% of control values in addition to the delay of exocytosis of cysteine proteases. Fusion among endocytic compartments was not inhibited in the presence of dibucaine because previously labeled reservosomes was loaded with a second label in sequential pulse-chase experiments. However, dibucaine reduced the degradation of BSA-gold complex in the reservosomes, which was not caused either by an inhibition of the whole proteolytic activity of the parasite or by a reduction on the expression levels of cruzipain. The immunocytochemical analysis suggested that the inhibition of the degradation of gold-labeled BSA in reservosomes could be due to a subversion of the regular traffic of proteases toward the reservosomes in dibucaine-treated cells.

Anti-Leishmania effect of intralesional procaine and dibucaine in hamsters

Se compara el efecto terapéutico de los anestésicos locales "caínicos" Procaína y Dibucaína administrados intralesionalmente (IL), con el del tratamiento intramuscular (IM) convencional con Glucantime®, para lograr la cura clínica y parasitológica sobre lesiones dérmicas en la base de la cola de hámsters machos heterocigotos experimentalemente infectados con 4 x 10³ amastigotes de Leishmania (Viannia) braziliensis. Los resultados revelaron que todas las drogas ensayadas reducen significativamente (P<0,01) los tamaños promedio de las lesiones granulomatosas, cuando se comparan con los aninales controles sin tratamiento. El tratamiento local con la Dibucaína fue tan eficaz clínicamente como el Glucantime® administrado sistémicamente, y tuvo mejor eficacia para la resolución clínica de las lesiones que la Procaína IL. Se detectó la presencia de amastigotes viables en nódulos granulomatosos o cicatrices en su totalidad de los hámsters evaluados, después de 75-165 días de haberse finalizado los tratamientos, mediantes los métodos de frotis directo, histopatología convencional, medios de cultivo (NNN) y la técnica de la inmunoperoxidasa, lo que sugiere que la medición de las lesiones cutáneas por sí solo no es un método totalmente confiable y válido para evaluar la eficacia quimioterapéutica en la LC experimental. La eficiencia clínica de los anestésicos locales parece estar relacionada con sus tiempos de vida media y lipofilia relativa. De una manera preliminar, estos resultados parecieran apoyar la inclusión de los anestésicos locales "caínicos" como parte del armamentarium alternativo para el tratamiento de las LC animal y humana

Dibucaine-induced modification of sodium transport in toad skin and of model membrane structures.

The interaction of the local anesthetic dibucaine with the isolated toad skin and membrane models is described. The latter consisted of human erythrocytes, isolated unsealed human erythrocyte membranes (IUM), large unilamellar vesicles (LUV) of dimyristoylphosphatidylcholine (DMPC) and phospholipid multilayers built-up of DMPC and dimyristoylphosphatidylethanolamine (DMPE), representative of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. Results indicate a significant decrease in the potential difference (PD) and in the short-circuit current (Isc) after the application of dibucaine in toad skin, which may be interpreted as reflecting inhibition of the active transport of ions. This finding might be explained on the basis of the results obtained from fluorescence spectroscopy and X-ray diffraction studies on membrane models. In fact, dibucaine induced structural perturbations in IUM, DMPC LUV and phospholipid multilayers. Scanning electron microscopy revealed that dibucaine induced erythrocyte stomatocytosis. According to the bilayer couple hypothesis an echinocytic type of shape change would have been expected given the preferential interaction of dibucaine with DMPC. Although it is still premature to define the molecular mechanism of action of dibucaine, the experimental results confirm the important role played by the phospholipid bilayers in the association of the anesthetic with cell membranes.

[Analytical review of multicenter studies with polycresulene for hemorrhoidal pathologies]. / Revisión analítica de estudios multicéntricos con policresuleno en patología hemorroidal.

Seven centres investigated the therapeutic efficacy and tolerability of policresulene associated to cinchocaine administered locally as ointment, suppositories or both formulations in 2287 patients with hemorrhoid pathology. The studies were conducted with a standardised protocol and case report forms and with the same score criteria for rating efficacy and tolerability according to the physicians and the patients. Highly satisfactory results were achieved in 1904 patients (83.2%) according to the investigators criteria. Patients rated the outcome most satisfactory for 1881 cases (82.2%). The following were found to be the principal indications: external and internal hemorrhoids associated with bleeding, acute anal fissures, rhagades and perforated or incised perianal thrombosis, anal eczema and anal pruritus, proctitis and wound treatment after proctologic surgery. None of the investigators found any serious adverse event. Mild to moderate adverse reactions in 10% of the patients were local discomfort, pruritus, burning or irritation. Such symptoms occurred at the beginning of treatment. The favourable effects of policresulene are attributed to its unique mechanism of action. The highly acid characteristics of the substance causes a selective coagulation of the necrotic tissues leaving healthy tissues unaffected. The desquamation and remotion of the necrotic tissues induces rapid wound cleansing, and a reactive hyperemia of the treated area enhancing epithelization. Its highly acid pH produces a marked bactericidal action on the most common pathogens and C. albicans as well. Policresulene has hemostyptic properties producing vasoconstriction of the myofibrils of the blood vessels arresting profuse bleeding from large areas. The local anesthetic cinchocaine contributes to the initial pain relief. None of the formulations contains corticosteroids which makes this preparations also suitable for long term treatment periods.

Revisión analítica de estudios multicéntricos con policresuleno en patología hemorroidal / Analytical review of multicenter studies with polycresulene for hemorrhoidal pathologies

Seven centers investigated the therapeutic efficacy and tolerability of policresulene associated to cinchocaine administered locally as ointment, suppositories or both formulations in 2287 patients with hemorrhoid pathology. The studies were conducted with a standardised protocol and case report forms and with the same score criteria for rating efficacy and tolerability according to the physicians and the patients. Highly satisfactory results were achieved in 1904 patients (83.2 per cent) according to the investigators criteria. Patients rated the outcome most satisfactory for 1881 cases (82.2 per cent). The following were found to be the principal indications: external and internal hemorrhoids associated with bleeding, acute anal fissures, rhagades and perforated or incised perianal thrombosis, anal eczema and anal pruritus, proctitis and wound treatment after proctologic surgery. None of the investigators found any serious adverse event. Mild to moderate adverse reactions in 10 per cent of the patients were local discomfort, pruritus, burning or irritation. Such symptoms occurred at the beginning of treatment. The favourable effects of pol icresulene are attributed to its unique mechanism of action. The highly acid characteristic of the substance causes a selective coagulation of the necrotic tissues leaving healthy tissues unaffected. The desquamation and remotion of the necrotic tissues induces rapid wound cleansing, and a reactive hyperemia of the treated area enhancing epithelization. Its highly acid pH produces a marked bactericidal action on the most common pathogens and C. albicans as well. Policresulene has hemostyptic properties producing vasoconstriction of the myofibrils of the blood vessels arresting profuse bleeding from large areas. The local anesthetic cinchocaine contributes to the initial pain relief. None of the formulations contains corticosteroids which makes this preparations also suitable for long term treatment periods.

Revisión analítica de estudios multicéntricos con policresuleno en patología hemorroidal / Analytical review of multicenter studies with polycresulene for hemorrhoidal pathologies

Seven centers investigated the therapeutic efficacy and tolerability of policresulene associated to cinchocaine administered locally as ointment, suppositories or both formulations in 2287 patients with hemorrhoid pathology. The studies were conducted with a standardised protocol and case report forms and with the same score criteria for rating efficacy and tolerability according to the physicians and the patients. Highly satisfactory results were achieved in 1904 patients (83.2 per cent) according to the investigators criteria. Patients rated the outcome most satisfactory for 1881 cases (82.2 per cent). The following were found to be the principal indications: external and internal hemorrhoids associated with bleeding, acute anal fissures, rhagades and perforated or incised perianal thrombosis, anal eczema and anal pruritus, proctitis and wound treatment after proctologic surgery. None of the investigators found any serious adverse event. Mild to moderate adverse reactions in 10 per cent of the patients were local discomfort, pruritus, burning or irritation. Such symptoms occurred at the beginning of treatment. The favourable effects of pol icresulene are attributed to its unique mechanism of action. The highly acid characteristic of the substance causes a selective coagulation of the necrotic tissues leaving healthy tissues unaffected. The desquamation and remotion of the necrotic tissues induces rapid wound cleansing, and a reactive hyperemia of the treated area enhancing epithelization. Its highly acid pH produces a marked bactericidal action on the most common pathogens and C. albicans as well. Policresulene has hemostyptic properties producing vasoconstriction of the myofibrils of the blood vessels arresting profuse bleeding from large areas. The local anesthetic cinchocaine contributes to the initial pain relief. None of the formulations contains corticosteroids which makes this preparations also suitable for long term treatment periods. (Au)

Membrane effects of trifluoperazine, dibucaine and praziquantel on human erythrocytes.

Trifluoperazine (TFP) is a potent antipsychotic agent, dibucaine (DBC) is a local anaesthetic and praziquantel (PZQ) is a highly effective agent against schistosomiasis. The present work was conducted to (i) investigate the cytotoxic effects of TFP, DBC and PZQ on human erythrocyte membranes; and (ii) compare the alterations induced by the cationic drugs (TFP and DBC) with those induced by the uncharged compound (PZQ), in an attempt to have a better insight on the pathways of each drug-membrane interaction. The erythrocyte morphological alterations induced by sublytic concentrations of TFP, DBC and PZQ were evaluated by scanning electron microscopy and expressed quantitatively by the morphological index. Haemolysis and release of membrane lipids (phospholipids and cholesterol) produced by selected concentrations of TFP, DBC and PZQ, were compared with those resulting from the corresponding triple concentrations of each drug. Our results showed that the uncharged molecule of PZQ induces the same morphological alterations (stomatocytosis) as the cationic drugs TFP and DBC. Haemolysis was shown to vary with the drug used and to be concentration-dependent, with values approximately 10-fold more elevated for TFP and DBC than for PZQ, which revealed a maximum of 6% haemolysis for the highest concentration tested. Different concentration-response curves were obtained for lipid elution, although the profiles of cholesterol and phospholipids released were similar for all drugs. Nevertheless, at a fixed rate of 50% haemolysis, TFP induced a approximately 2-fold increment in the elution of cholesterol when compared with that produced by DBC (P<0. 05). The different effects induced by TFP, DBC and PZQ on erythrocyte morphology, haemolysis and lipid exfoliation are related to the physical and chemical characteristics of each compound. These results suggest that distinct cell membrane interaction pathways lead to drug-specific mechanisms of cytotoxicity.

Pathways involved in trifluoperazine-, dibucaine- and praziquantel-induced hemolysis.

This work elucidates differences in the hemolytic pathway developed by the antipsychotic trifluoperazine (TFP), the local anesthetic dibucaine (DBC) and the antihelminthic praziquantel (PZQ). Their partition coefficients (P) were measured at pH 7.4 between n-octanol, microsomes, liposomes, erythrocyte ghosts and n-octanol/water. The effective drug:lipid molar ratios for the onset of membrane solubilization (ReSAT) and complete hemolysis (ReSOL) were calculated from the experimental P values and compared with a classical surface-active compound treatment Lichtenberg, D. Biochim. Biophys. Acta 821 (1985) 470-478[. The contribution of charged/uncharged forms of TFP and DBC for the hemolytic activity was also analyzed. In all cases the hemolytic phenomena could be related to the monomeric drug insertion into the membrane. Only for TFP at isosmotic condition lysis occurs at concentrations beyond the CMC of the drug, indicating that micellization facilitates TFP hemolytic effect, while DBC and PZQ reach a real membrane saturation at their monomeric form.

Ca2+-stimulated mitochondrial reactive oxygen species generation and permeability transition are inhibited by dibucaine or Mg2+.

Mitochondrial swelling and membrane protein thiol oxidation associated with mitochondrial permeability transition induced by Ca2+ and t-butyl hydroperoxide or inorganic phosphate, but not 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid or phenylarsine oxide, are inhibited by the local anesthetic dibucaine. Dibucaine promotes an inhibition of the Ca2+-induced increase in mitochondrial H2O2 generation measured by the oxidation of scopoletin in the presence of horseradish peroxidase. This decrease in mitochondrial H2O2 generation may be attributed to the reduction of Ca2+ binding to the membrane induced by dibucaine, as assessed by measuring 45Ca2+ binding to the mitochondrial membrane. Mg2+ also inhibited Ca2+ binding to the mitochondrial membrane, mitochondrial swelling, membrane protein thiol oxidation, and H2O2 generation induced by Ca2+. Together, these results demonstrate that the mechanism by which dibucaine and Mg2+ inhibit mitochondrial permeability transition is related to the decrease in reactive oxygen species generation induced by Ca2+-promoted alterations of inner mitochondrial membrane properties.

The action of local anesthetics on myelin structure and nerve conduction in toad sciatic nerve.

X-ray scattering and electrophysiological experiments were performed on toad sciatic nerves in the presence of local anesthetics. In vitro experiments were performed on dissected nerves superfused with Ringer's solutions containing procaine, lidocaine, tetracaine, or dibucaine. In vivo experiments were performed on nerves dissected from animals anesthesized by targeted injections of tetracaine-containing solutions. In all cases the anesthetics were found to have the same effects on the x-ray scattering spectra: the intensity ratio of the even-order to the odd-order reflections increases and the lattice parameter increases. These changes are reversible upon removal of the anesthetic. The magnitude of the structural changes varies with the duration of the superfusion and with the nature and concentration of the anesthetic molecule. A striking quantitative correlation was observed between the structural effects and the potency of the anesthetic. Electron density profiles, which hardly showed any structural alteration of the unit membrane, clearly indicated that the anesthetics have the effect of moving the pairs of membranes apart by increasing the thickness of the cytoplasmic space. Electrophysiological measurements performed on the very samples used in the x-ray scattering experiments showed that the amplitude of the compound action potential is affected earlier than the structure of myelin (as revealed by the x-ray scattering experiments), whereas conduction velocity closely follows the structural alterations.

Interaction of alkanols and local anesthetics with spin-labeled Ca(2+)-ATPase of sarcoplasmic reticulum vesicles.

Alkanols and tertiary amine derivative local anesthetics modify the activity of Ca(2+)-ATPase. In order to investigate the primary binding sites, associated to the functional changes, sarcoplasmic reticulum (SR) Ca(2+)-ATPase was labeled with maleimide derivative spin labels which bind covalently to SH groups of cysteine residues and allow to probe the regions of the protein close to those residues. The EPR measurements showed motional constraints induced by drug-treatment which indicate changes in the enzyme dynamics and structure. n-Alkanols are shown to affect some of the protein-bound labels by restricting their motion. There is, however, no correlation between the functional effects and the observed motional restriction, in the sense that concentrations of the different alcohols leading to the same functional effects do not induce the same degree of restriction. Dibucaine and tetracaine at functional relevant concentrations also restrict the movement of protein bound labels. But, in this case, correlation between spectral changes and functional effects is observed.

Distribution of cholinesterase activity in the population of Trinidad.

The relation between the level or the quality of serum cholinesterase and susceptibility to succinylcholine-induced apnea is significant because the abnormality resides in a low affinity variant rather than in a quantitative deficiency. A population study was undertaken in Trinidad to determine the pattern of the cholinesterase phenotype, using quantitative biochemical tests and the dibucaine number. Of 1290 subjects, 567 were African, 418 were Indian, 237 were of mixed lineage, and 68 belonged to the minority races. The dibucaine number did not differ between races or sexes. Of the population, 98.5% had normal enzyme characteristics. Indians had the highest values for the dibucaine number and the enzyme activity. Cholinesterase was significantly higher in African and mixed males. The homozygous atypical gene was not detected, but the frequency of the heterozygous "atypical" variant was highest in the minority races and lowest in Africans. Two sisters of Indian descent demonstrated the presence of the silent gene.