Úlceras por Presión: Manejo Quirúrgico en Pacientes de un Centro Nacional de Rehabilitación / Pressure Sores: Surgical Management in a Nacional Rehabilitation Centre

Las úlceras por presión representan una patología importante y frecuente hoy en día. Muchas series publicadas refieren porcentajes de recidiva altos con diferentes técnicas quirúrgicas. En nuestro medio no encontramos estudios previos de resultados del manejo quirúrgico de esta patología. Por lo tanto, nos dispusimos analizar el manejo de las úlceras por presión en un hospital de referencia como es el Centro Nacional de Rehabilitación (CENARE), donde realizamos un estudio longitudinal y retrospectivo en 50 pacientes con 63 ulceras por presión en el periodo comprendido entre Agosto de 1997 y Agosto (le 1999. Se utilizaron variables de sexo, edad, factores de riesgo, tipo y grado de úlcera, tiempo de estancia hospitalaria, procedimiento quirúrgico, complicaciones y recurrencia. La mayoría de los pacientes estudiados fueron hombres ( 78 por ciento) y la edad media fue de 30,9 años. El estado parapléjico fue predominante en 60 por ciento de los pacientes. La localización mas común de la úlcera fue isquiática ( 47,6 por ciento ), seguida por la sacra ( 38,1 por ciento ) y la trocantérea ( 14,9 por ciento ). La técnica quirúrgica mas empleada fue el colgajo músculo cutáneo. Las dehiscencias aparecieron en 25,4 por ciento de las úlceras lo cual represento la mayoría de las complicaciones y la principal causa de prolongación de la estancia hospitalaria. El porcentaje de recidiva total fue de 17,4 por ciento. Las úlceras cerradas con el método de cierre combinado de un colgajo muscular más un colgajo fasciocutáneo fueron las que en proporción tuvieron menor estancia hospitalaria y la prueba estadística resultó ser significativa (AU)

[The serum of newborn Clelia clelia (Serpentes: Colubridae) neutralizes the hemorrhagic action of Brothrops asper venom (Serpentes: Viperidae)]. / El suero de neonatos de Clelia clelia (Serpentes: Colubridae) neutraliza la acción hemorrágica del veneno de Bothrops asper (Serpentes: Viperidae).

The ability of serum from nine newborn specimens of Clelia clelia (Colubridae) to neutralize hemorrhagic action of Bothrops asper venom was tested. All serum samples neutralized completely the hemorrhagic effect of the venom in mice. This finding shows that the neutralizing ability of C. clelia serum towards the hemorrhagic activity of B. asper venom is innate.

Histopathological and biochemical alterations induced by intramuscular injection of Bothrops asper (terciopelo) venom in mice.

The local and systemic pathological changes induced by an i.m. injection of 100 micrograms of Bothrops asper venom in mice were studied histologically and by following the changes in serum levels of enzymes, proteins, ATP and lactate, as well as alterations in hematocrit and clotting time. B. asper venom induced a rapid and marked increase in serum levels of creatine kinase, aspartate aminotransferase and lactate dehydrogenase, but not alanine aminotransferase or alkaline phosphatase. A local myonecrosis and hemorrhage was observed, with the lungs collapsing by 24 hr and the kidneys showing glomerular congestion and vacuolar degeneration of tubular cells. Only minor histopathological changes were observed in cardiac muscle and liver. Both ATP and lactate blood levels decreased after venom injection, whereas there were no changes in serum protein concentration. Blood incoagulability was observed 1 and 3 hr after envenomation. Antivenom neutralized venom-induced increases in serum enzyme levels following preincubation with venom, indicating that antivenom contains antibodies against tissue-damaging toxins. However, when antivenom was administered i.v. at different time intervals after venom injection, neutralization was only partial, with the exception of defibrinating activity, which was totally neutralized even after a delay of 1 hr in administering antivenom.

Comparative study on coagulant, defibrinating, fibrinolytic and fibrinogenolytic activities of Costa Rican crotaline snake venoms and their neutralization by a polyvalent antivenom.

The coagulant, defibrinating, fibrino lytic and fibrinogenolytic activities of venoms from ten species of Costa Rican crotaline snakes were studied, together with the neutralization of these effects by a polyvalent antivenom. The venoms of Bothrops asper, B. schlegelii, B. nummifer, B. godmani, Lachesis muta and Crotalus durissus induced a coagulant effect in vitro, and all of them, with the exception of B. nummifer, also induced defibrination in vivo. The four non-coagulant venoms (B. lateralis, B. ophryomegas, B. nasuta and B. picadoi) induced a degradation of the alpha (A) chain of fibrinogen, thereby inhibiting coagulation. However, they did not induce defibrination upon i.v. injection. All of the venoms showed fibrinolytic activity in vitro. Polyvalent antivenom was effective in the neutralization of coagulant, defibrinating, fibrinolytic and fibrinogenolytic activities of these venoms, with the exception of coagulant effect induced by C. durissus venom. Since only three venoms are used in the immunization of horses, these results demonstrate the high degree of immunological cross reactivity between components affecting coagulation in Costa Rican crotaline snake venoms.

[Bothrops ophryomegas Bocourt (Serpentes: Viperidae) in Costa Rica: distribution, lepidosis, sexual variation and karyotype]. / Bothrops ophryomegas Bocourt (Serpentes: Viperidae) en Costa Rica: distribución, lepidosis, variación sexual y cariotipo.

The distribution, karyotype and morphological characteristics of Bothrops ophryomegas from Costa Rica are described. This species presents a conspicuous sexual dimorphism and dichromatism. It is distributed in the dry forest areas of Guanacaste and Puntarenas. Its karyotype is indistinguisable from those described for other crotaline species.

[Reproductive biology of the Central American rattlesnake Crotalus durissus durissus (Serpentes: Viperidae) in Costa Rica]. / Biología reproductiva de la cascabel centroamericana Crotalus durissus durissus (Serpentes: Viperidae) en Costa Rica.

In Costa Rica, rattlesnakes mate during the early dry season (December and January) and births occur in the early rainy season (May-July). Gestation is therefore about 6 months. The mean number of offspring is 22.9 and is significantly correlated with the size of the female. Newborn rattlesnakes are 27.5-43.0 cm in length and weight 11.4-46.3 g. They are relatively docile. Adult males are longer and heavier than females. Females seem to have their first litter when their size exceeds 120 cm.

[Reproductive cycles of the coral snake Micrurus nigrocinctus (Serpentes: Elapidae) in Costa Rica]. / Ciclos reproductivos de la serpiente coral Micrurus nigrocinctus (Serpentes: Elapidae) en Costa Rica.

The coral snake Micrurus nigrocinctus has two reproductive patterns in Costa Rica. Specimens of the Pacific population (M. n. nigrocinctus) mate during the early dry season (November, January). Oviposition takes place in February and March; the mean number of eggs was 7.9 (5-14) in this population. Births occur between April and June after 47-81 days of incubation. The total length of neonates is 168-212 mm, and the weight is 1.2-2.0 g. Specimens of the Atlantic population (M. n. mosquitensis) seem to have an extended breeding season. Oviposition in this subspecies was observed in March and June; the mean number of eggs was 6.7 (5-8). Births take place in May and August, after two months of incubation. Neonates have 173-189 mm in total length and 1.9-2.4 g in mass. Adult females are longer than males, especially in M. n. mosquitensis.

Production of monovalent anti-Bothrops asper antivenom: development of immune response in horses and neutralizing ability.

A monovalent antivenom was produced by immunizing two horses with venom of the pit viper Bothrops asper (Ophidia: Viperidae). Although development of the immune response against four toxic and enzymatic activities of the venom was similar in both horses during the first two thirds of the immunization schedule, antibody response in one of the horses reached much higher levels in the last part of the immunization. Immunoelectrophoretic analysis indicates that there were precipitating antibodies in the sera of these horses during all the stages of immunization. However, immunoprecipitation did not correlate with the ability of sera to neutralize toxic activities of B. asper venom. Monovalent antivenom was more effective than the commercially available polyvalent antivenom in the neutralization of Bothrops asper venom. On the other hand, despite the fact that it neutralizes lethal and hemorrhagic activities of the venoms of Lachesia muta and Crotalus durissus durissus, it was less effective than polyvalent antivenom in these neutralizations. Moreover, it does not neutralize defibrinating activity induced by these two venoms, whereas it neutralizes this effect in the case of B. asper venom. It is proposed that monovalent antivenom may be highly effective in the case of envenomations induced by Bothrops asper venom; its use in treating accidents by L. muta and C. durissus would be indicated only if polyvalent antivenom is not available. Results also demonstrate that it is important to monitor antibody response individually in horses being immunized for antivenom production, due to the conspicuous variability in the response of different animals.

An alternative in vitro method for testing the potency of the polyvalent antivenom produced in Costa Rica.

The ability of several batches of polyvalent antivenom to neutralize indirect hemolytic activity of Bothrops asper venom was studied using a sensitive plate test. All samples of antivenom tested effectively neutralized this activity. A highly significant correlation was observed between neutralization of indirect hemolysis and neutralization of lethal activity. This simple and sensitive in vitro test could be used to monitor antibody levels in horses immunized to produce polyvalent antivenom.

[Neutralization of toxic and enzyme activities of 4 venoms from snakes of Guatemala and Honduras by the polyvalent antivenin produced in Costa Rica]. / Neutralización de las actividades tóxicas y enzimáticas de cuatro venenos de serpientes de Guatemala y Honduras por el antiveneno polivalente producido en Costa Rica.

We studied the ability of the polyvalent antivenom produced in Costa Rica to neutralize lethal, hemorrhagic, edema-forming, proteolytic, hemolytic, hyaluronidase and fibrinolytic activities of the venoms of Bothrops asper and B. nummifer from Honduras, and of Agkistrodon bilineatus and Crotalus durissus durissus from Guatemala. Neutralizing ability of antivenom was expressed as ED50 (effective dose 50%), defined as the antivenom/venom ratio at which the activity of the venom is reduced 50%. Antivenom is highly effective in the neutralization of lethal, hemorrhagic, hemolytic, hyaluronidase, and caseinolytic activities of B. asper, B. nummifer, and C. d. durissus venoms. In the case of B. nummifer venom, neutralization of fibrinolytic effect was only partial, whereas this activity was adequately neutralized when studying the venoms of B. asper and C. d. durissus. The venom of A. bilineatus was adequately neutralized by the antivenom, with the only exception of hemolytic effect that was reduced only partially. However, in quantitative terms, a relatively large volume of antivenom was required to neutralize some effects induced by A. bilineatus venom. Regarding edema-forming activity, antivenom neutralized efficiently the venoms of B. asper and A. bilineatus, whereas that of B. nummifer was neutralized only partially; on the other hand, edema induced by the venom of C. d. durissus was not neutralized at all. Immunochemical results indicate a close immunological relationship between venoms of B. asper, B. nummifer and C. d. durissus collected in Honduras and Guatemala with those of the same species collected in Costa Rica. Interspecies comparison, however, showed variation between venoms obtained from different species.(ABSTRACT TRUNCATED AT 250 WORDS)

Skeletal muscle necrosis induced by a phospholipase A2 isolated from the venom of the coral snake Micrurus nigrocinctus nigrocinctus.

1. The venom of the coral snake Micrurus nigrocinctus nigrocinctus was fractionated by reverse-phase high performance liquid chromatography and an acidic myotoxic phospholipase A2 was purified to homogeneity. 2. After intramuscular injection, the toxin induced rapid and drastic myonecrosis, as serum creatine kinase levels increased markedly, reaching their highest values by 1.5 hr. 3. Ultrastructural observations indicate that the plasma membrane was the first structure to be affected, with the presence of focal disruptions in its integrity. 4. Myofilaments were hypercontracted and formed dense clumps. Sarcoplasmic reticulum integrity was lost, as evidenced by the presence of many small vesicles in the cellular space. 5. Some mitochondria were swollen, whereas others contained dense intracristal spaces and flocculent densities. Moreover, some had only one membrane. 6. In conclusion, pathogenesis of myonecrosis induced by this phospholipase A2 is similar to that induced by crude Micrurus nigrocinctus nigrocinctus venom.

Ability of a polyvalent antivenom to neutralize the venom of Lachesis muta melanocephala, a new Costa Rican subspecies of the bushmaster.

Several toxic and enzymatic activities of the venom of L. m. melanocephala were studied. This venom has many similarities with that of L. m. stenophrys, although there are quantitative differences in venom activities, as well as in the immunodiffusion patterns of these venoms when reacted against polyvalent antivenom. This antivenom was tested for its ability to neutralize a series of toxic and enzymatic effects of L. m. melanocephala venom. A new method to study myonecrosis, based on the quantitation of residual creatine kinase in injected muscle, was used. Antivenom was highly effective in neutralizing lethal, hemorrhagic, myotoxic, edema-forming, defibrinating, caseinolytic and fibrinolytic activities when venom and antivenom were incubated prior to the test or, in the case of edema-forming activity, when antivenom was administered before venom injection. On the other hand, when antivenom was injected i.v. at different time intervals after venom injection neutralization of lethality was good, although neutralization of local effects, i.e. hemorrhage and edema, was poor. These results indicate that polyvalent antivenom contains antibodies capable of neutralizing toxic and enzymatic activities of L. m. melanocephala venom. Moreover, the partial inability of antivenom to neutralize local effects when administered after venom injection is probably due to the rapid development of these effects once venom is injected.

Antibody neutralization of a myotoxin from the venom of Bothrops asper (terciopelo).

Neutralization of biological activities of B. asper myotoxin by a monospecific anti-myotoxin rabbit serum and polyvalent antivenom was studied. Both antisera neutralized myotoxic, phospholipase A and lethal activities of myotoxin, whereas edema-forming activity of myotoxin was not neutralized by these antisera. Anti-myotoxin rabbit serum neutralized most of the myotoxic activity of B. asper venom, but did not neutralize phospholipase A activity of this venom. Neutralization curves showed that myotoxicity induced by myotoxin persisted at antivenom/toxin or antiserum/toxin ratios at which phospholipase A activity was completely neutralized. This suggests that myotoxicity does not depend upon enzymatic activity of the toxin. Antiserum to myotoxin neutralized approximately 70% of myonecrosis induced by crude B. asper venom. This demonstrates that myotoxin is the main factor responsible for the development of myonecrosis in envenomations by B. asper.

Effects of a myotoxic phospholipase A2 isolated from Bothrops asper venom on skeletal muscle sarcoplasmic reticulum.

The myotoxin from B. asper snake venom inhibited Ca-ATPase activity of rabbit sarcoplasmic reticulum after incubation in vitro. Inhibition was non-competitive and albumin enhanced the effect of the toxin. Furthermore, B. asper myotoxin hydrolyzed sarcoplasmic reticulum phospholipids and induced a dose-dependent release of horseradish peroxidase that had been trapped in sarcoplasmic reticulum vesicles. Binding studies indicated that myotoxin does not bind to any particular protein of this membrane, suggesting that the toxin might interact with phospholipids. Inhibition of Ca-ATPase is probably a consequence of an alteration in sarcoplasmic reticulum phospholipids.

Inflammatory infiltrate in skeletal muscle injected with Bothrops asper venom.

The time-course and composition of inflammatory infiltrate in mouse gastrocnemius injected with Bothrops asper venom was studied. The venom induced myonecrosis, and a prominent decrease in muscle levels of creatine kinase (CK) as early as 3 hr after envenomation. Inflammatory infiltrate was scarce by 6 hr. but increased markedly at 24, 48 and 72 hr. Samples of infiltrate obtained at 6 and 24 hr contained polymorphonuclear leucocytes as the predominant cell type, whereas at 48 hr and 72 hr the relative number of macrophages increased. Inflammatory cells were located within necrotic muscle cells, as well as in the interstitial space, but there were some necrotic areas devoid of inflammatory cells even one week after envenomation. When correlating the presence of inflammatory cells with degradation of myofibrillar proteins, it was observed that at 6 hr there was little muscle protein degradation. By 48 hr a decrease in "non collagen" proteins was observed, together with a reduction in some myofibrillar components, as judged by electrophoresis. Proteolytic enzymes of inflammatory cells may play an important role in myofibrillar protein degradation after myonecrosis induced by B. asper venom.

Pathogenesis of myonecrosis induced by coral snake (Micrurus nigrocinctus) venom in mice.

The mode by which coral snake (Micrurus nigrocinctus) venom affects skeletal muscle was studied using a combined approach. The venom induced early functional and structural alterations in the plasma membrane of muscle cells, suggesting that sarcolemma is the primary site of action of this venom. This was shown by the presence of wedge-shaped ('delta') lesions at the periphery of the cells, as well as by focal disruptions in the continuity of plasma membrane as early as 15 min after envenomation. After this initial alteration the rest of the organelles were severely affected. Myofilaments were hypercontracted leaving, as a consequence, areas of overstretched myofibrils as well as empty spaces. Eventually, myofilaments formed dense, clumped masses in which the striated structure was totally lost. At 24 h, myofilaments were still disorganized but they presented a more hyaline and homogeneous appearance. As early as 15 and 30 min mitochondria were swollen; later, by I, 3 and 24 h, they showed further alterations such as the presence of dense intracristal spaces and vesiculated cristae, as well as disruption in the integrity of their membranes. Sarcoplasmic reticulum was dilated and disorganized into many small vesicles randomly distributed throughout the cellular space. Moreover, the venom induced a rapid decrease in muscle levels of creatine and creatine-kinase (CK) and a calcium influx. Since the rates of efflux of creatine and CK were similar, it is suggested that the lesions produced in the membrane are large enough to allow the escape of these two molecules. As corroboration of the severe myotoxic effect, envenomated mice excreted reddish urine containing large quantities of myoglobin. Skeletal muscle cells are more susceptible to the action of the venom than erythrocytes, since coral snake venom induced only a mild direct haemolytic effect in vitro and haemolysis is not a significant effect in vivo. M. nigrocinctus venom induced a drastic increase in plasma levels of lactate dehydrogenase. Isozymes LDH-3, LDH-4, and LDH-5 increased markedly, suggesting that the systemic pathology of coral snake envenoming may be more complex than previously thought.

Comparative study of the edema-forming activity of Costa Rican snake venoms and its neutralization by a polyvalent antivenom.

The edema-forming activity of eight Costa Rican crotaline snake venoms and its neutralization by a polyvalent antivenom were studied using the mouse footpad test. All of the venoms induced edema, the highest activity being present in the venoms of Bothrops lateralis and Bothrops picadoi. When experiments were performed with preincubation of venom and antivenom, neutralization of edema was poor. Moreover, it was observed that, with some venoms, edema increased when large doses of antivenom were used. This effect was also observed when some venoms were incubated with coral snake antivenom, suggesting that venoms may release some pharmacologically active component(s) from antivenom, since the latter contains traces of alpha-2 and beta globulins. Based on these findings, an alternative approach to the study of the neutralization of edema was used; in this new method, antivenom was injected i.v. before venom administration, thereby avoiding preincubation. With this technique, a much better neutralization of edema was observed, although with some venoms it was still poor. Venoms contain low molecular weight factors which induce edema, suggesting that lack of immunogenicity of some components may cause a poor neutralization. However, such components are responsible for only a minor portion of the edema induced by crude venoms. It is suggested that experiments in which venom and antivenom are preincubated preincubated in testing the neutralization of edema should be avoided, and that a more adequate approach may be an independent inoculation of venom and antivenom.

Skeletal muscle regeneration after myonecrosis induced by Bothrops asper (terciopelo) venom.

In order to assess the extent of regeneration, creatine kinase content of injected gastrocnemius muscle were determined at four time intervals after inoculation. Simultaneously, the diameters of regenerating fibers were measured, the wet weight of the gastrocnemius was recorded and electrophoretic patterns of muscle proteins and histology of the tissue were analyzed. Injection of crude B. asper venom caused myonecrosis and hemorrhage; in these cases regeneration was very poor, as there was only a small increase in creatine kinase content by four weeks. Histologically, large areas of fibrosis were observed, intermixed with small areas of regenerating muscle. Furthermore, the diameter of regenerating muscle cells was abnormally small, even four weeks after envenomation. In order to test the role of hemorrhage in impairment of regeneration, we also studied the effects of B. asper venom that had been incubated with a volume of antivenom that completely neutralized hemorrhagic activity, but not myotoxic activity. At 24 hr mice showed a generalized picture of myonecrosis, without hemorrhage. Afterwards, regeneration proceeded and significant increases in creatine kinase content were demonstrated at 1, 2 and 4 weeks. Also, histological observations showed the presence of many areas of regenerating muscle, intermixed with small areas of fibrosis and adipose tissue. The diameter of regenerating cells increased with time, reaching values of 25.8 microns by four weeks. Electrophoretic analyses of muscle proteins showed that muscle injected with partially neutralized venom underwent a more complete regeneration than muscle injected with crude venom.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation and partial characterization of a myotoxin from the venom of the snake Bothrops nummifer.

A myotoxin from the venom of the snake Bothrops nummifer was purified to homogeneity by ion-exchange chromatography on CM-Sephadex. The toxin is a basic dimer with a subunit molecular weight of 16,000, as estimated by SDS-polyacrylamide gel electrophoresis. The toxin lacks phospholipase A2 activity when tested on egg yolk lecithin and skeletal muscle homogenates. It induces skeletal muscle damage both in vivo and in vitro. When injected i.m. it promotes a drastic increase in serum creatine kinase levels; the isozyme CK-MM is responsible for this increment. A rapid release of creatine kinase was observed when mouse gastrocnemius muscle was incubated with the toxin, suggesting that it induces the formation of relatively large 'lesions' in the plasma membrane of muscle cells. Moreover, analysis of the dose-response data indicated that the myotoxin affects muscle sarcolemma by a 'one hit' mechanism. Skeletal muscle cells are affected by the toxin when calcium is eliminated from the medium. The myotoxin has an i.v. LD50 of 3.9 mg/kg body weight in mice, and induces edema when injected in the foot pad. On the other hand, it is not directly hemolytic, anticoagulant, hemorrhagic nor cytotoxic for lymphocytes. The myotoxin shows partial immunologic identity with a myotoxic phospholipase A2 isolated from Bothrops asper venom. The polyvalent antivenom produced in Costa Rica forms a precipitation arc against B. nummifer myotoxin on immunoelectrophoresis.

Pharmacological activities of a toxic phospholipase A isolated from the venom of the snake Bothrops asper.

A toxic phospholipase A was isolated from the venom of Bothrops asper. It induced skeletal muscle damage, anticoagulant effects and edema in the foot pad. The toxin had an intravenous LD50 of 95 micrograms/16-18 g mouse body wt and an intraventricular LD50 of 0.42 micrograms/16-18 g mouse body wt. Upon intramuscular and intravenous injections, the toxin induced a prominent increase in serum creatine kinase (CK) levels; only the CK-MM isozyme increased markedly. The toxin induced CK and creatine release from skeletal muscle incubated in vitro. The rate of efflux of creatine was higher than that of CK, although both markers were partially released as early as 15 min after incubation. The toxin also induced elevation of serum levels of lactic dehydrogenase isozymes. However, histological examination of skeletal muscle, kidneys, heart and lungs revealed cell damage only in skeletal muscle. The toxin was not cytotoxic to erythrocytes, lymphocytes or macrophages. In addition, it did not induce a mitogenic response on lymphocytes. In the absence of albumin in the medium, there was no significant difference between myotoxic activities in Ca2+-free and Ca2+-containing bathing solutions. However, when albumin was added, there was a significantly higher myotoxic effect in the presence of Ca2+. Thus, although phospholipolytic activity of the toxin plays a role in muscle damage when albumin is present, the toxin induces muscle damage even when phospholipase A activity is inhibited.