Force feedback effects on single molecule hopping and pulling experiments.

Single-molecule experiments with optical tweezers have become an important tool to study the properties and mechanisms of biological systems, such as cells and nucleic acids. In particular, force unzipping experiments have been used to extract the thermodynamics and kinetics of folding and unfolding reactions. In hopping experiments, a molecule executes transitions between the unfolded and folded states at a preset value of the force [constant force mode (CFM) under force feedback] or trap position [passive mode (PM) without feedback] and the force-dependent kinetic rates extracted from the lifetime of each state (CFM) and the rupture force distributions (PM) using the Bell-Evans model. However, hopping experiments in the CFM are known to overestimate molecular distances and folding free energies for fast transitions compared to the response time of the feedback. In contrast, kinetic rate measurements from pulling experiments have been mostly done in the PM while the CFM is seldom implemented in pulling protocols. Here, we carry out hopping and pulling experiments in a short DNA hairpin in the PM and CFM at three different temperatures (6 °C, 25 °C, and 45 °C) exhibiting largely varying kinetic rates. As expected, we find that equilibrium hopping experiments in the CFM and PM perform well at 6 °C (where kinetics are slow), whereas the CFM overestimates molecular parameters at 45 °C (where kinetics are fast). In contrast, nonequilibrium pulling experiments perform well in both modes at all temperatures. This demonstrates that the same kind of feedback algorithm in the CFM leads to more reliable determination of the folding reaction parameters in irreversible pulling experiments.

Metabolic characteristics of the deltoid muscle in patients with chronic obstructive pulmonary disease.

The purpose of this study was to analyse key enzyme activities of the deltoid muscle (DM) in chronic obstructive pulmonary disease (COPD) patients. The activities of one oxidative enzyme (citrate synthase (CS)), two glycolytic enzymes (lacatate dehydrogenase (LD); and phosphofructokinase (PFK)) and one enzyme related to the use of energy stores (creatine kinase (CK)) were determined in the DM of 10 patients with COPD and nine controls. Exercise capacity (cycloergometry) and the handgrip strength were also evaluated. Although exercise capacity was markedly reduced in COPD (57 +/- 20% predicted), their handgrip strength was relatively preserved (77 +/- 19% pred). The activity of LD was higher in the COPD patients (263.9 +/- 68.2 versus 184.4 +/- 46.5 mmol x min(-1) x g(-1), p<0.01), with a similar trend for CS (67.3 +/- 33.3 versus 46.0 +/- 17.4 mmol x min(-1) x g(-1), p = 0.07). Interestingly, the activity of the latter enzyme was significantly higher than controls if only severe COPD patients were considered (81.8 +/- 31.2 mmol x min(-1) x g(-1), p < 0.01). PFK and CK activities were similar for controls and COPD. Chronic obstructive patients show a preserved or even increased (severe disease) oxidative capacity in their deltoid muscle. This coexists with a greater capacity in the anaerobic part of the glycolysis. These findings are different to those previously observed in muscles of the lower limbs.

[Metabolic activity of the external intercostal muscle of patients with COPD]. / Actividad metabólica del músculo intercostal externo en pacientes con EPOC.

INTRODUCTION: The external intercostal muscle is a relevant contributor to ventilatory work in situations of overloading. Like other respiratory muscles, the external intercostal muscle seems to undergo a process of structural remodeling to adapt to a situation of functional disadvantage. However, findings from published studies of morphology have differed to a certain degree. On the one hand, the proportion of fibers involved in anaerobic metabolism increases; on the other hand, the number of capillaries also increases, an occurrence that would facilitate aerobic metabolism. OBJECTIVE: This study was designed to analyze the activity of several key enzymes involved in the principal metabolic pathways in the external intercostal muscles of patients with COPD. METHODOLOGY: We studied 6 patients with COPD (65 +/- 8 years, BMI 23 +/- 3 kg/m2, FEV1 51 +/- 9% ref, RV 184 +/- 38% ref, PaO2 81 +/- 10 mmHg) and 6 control subjects matched for age and anthropometric variables but with normal lung function. External intercostal muscle samples were taken from each patient (fifth intercostal space, non-dominant side). The samples were treated by conventional spectrophotometry to determine enzyme activity as follows: citrate synthase (CS, Krebs cycle), phosphofructokinase (PFK, by common glycolysis), lactate dehydrogenase (LDH, anaerobic glycolysis) and creatine phosphokinase (CPK, use of energy reserves). RESULTS: Patients with COPD showed greater PFK enzyme activity (93 +/- 25 versus 44 +/- 9 micromol/min/g of fresh weight; p = 0.001) and LDH (308 +/- 42 versus 231 +/- 29 micromol/min/g; p < 0.01) than did control subjects. However, CS and CPK activity was similar in both groups (82 +/- 31 versus 90 +/- 20 micromol/min/g and 4017 +/- 1734 versus 3048 +/- 464 micromol/min/g, respectively), although the latter displayed noteworthy dispersion of values among COPD patients, with levels in some patients being three-fold greater than in controls. RV was directly related to glycolytic enzyme activity (with PFK, r = 0.716, p < 0.01; with LDH r = 0.697, p < 0.05) and PFK and LDH also correlated with each other (r = 0.737, p < 0.01). CONCLUSIONS: Based on the enzyme activity studied, oxidative activity seems to be conserved in the external intercostal muscle of patients with COPD. Activity in the glycolytic pathway seems to increase and the increase is proportional to the severity of COPD. These findings are probably the expression of a combination of adaptive structural factors.

Actividad metabólica del músculo intercostal externo en pacientes con EPOC / Metabolic activity of the external intercostal muscle of patients with COPD

INTRODUCCIÓN: El músculo intercostal externo (IE) contribuye de forma relevante al esfuerzo ventilatorio en situaciones de sobrecarga. Como otros músculos respiratorios, el IE parece participar en un proceso de remodelación estructural, para adaptarse a una situación funcional desventajosa. Sin embargo, los estudios morfológicos publicados ofrecen resultados hasta cierto punto divergentes. Por un lado, aumenta la proporción de fibras de metabolismo anaerobio, mientras que por otro se incrementa el número de capilares, lo que facilitaría el uso de un metabolismo de tipo aerobio.OBJETIVO: Este estudio se diseñó para analizar la actividad de diferentes enzimas clave, correspondientes a las principales vías metabólicas, en el IE de pacientes con enfermedad pulmonar obstructiva crónica (EPOC).METODOLOGÍA: Se estudiaron 6 pacientes con EPOC (65 ñ 8 años; índice de masa corporal [IMC]: 23 ñ 3 kg/m2; FEV1: 51 ñ 9 por ciento ref., volumen residual [RV: 184 ñ 38 por ciento ref.; PaO2: 81 ñ 100 mmHg) y 6 sujetos control, apareados por edad y características antropométricas, pero con función pulmonar normal. En todos ellos se procedió a la toma de muestras del IE (quinto espacio intercostal, lado no dominante), que fueron procesadas para la determinación de las siguientes actividades enzimáticas por espectrofotometría convencional: citratosintetasa (CS, ciclo de Krebs), fosfofructocinasa (PFK, vía glucolítica común), lactodeshidrogenasa (LDH, glucólisis anaerobia) y creatinfosfocinasa (CPK, uso de reservas energéticas).RESULTADOS: Los pacientes con EPOC presentaron mayor actividad de las enzimas PFK (93 ñ 25 frente a 44 ñ 9 µmol/min/g de peso en fresco; p = 0,001) y LDH (308 ñ 42 ante 231 ñ 29 µmol/min/g; p < 0,01) que los sujetos control. Por el contrario, las actividades de CS y CPK fueron similares (82 ñ 31 frente a 90 ñ 20 µmol/min/g, y 4.017 ñ 1.734 ante 3.048 ñ 464 µmol/min/g, respectivamente), aunque la segunda presentaba una dispersión muy notable de valores en los pacientes con EPOC, que en algunos casos triplicaban a los de los controles. El RV se correlacionó directamente con la actividad de las enzimas glucolíticas (con PFK, r = 0,716, p < 0,01; con LDH, r = 0,697, p < 0,05), que también se correlacionaban entre sí (r = 0,737, p < 0,01).CONCLUSIONES: A tenor de las actividades enzimáticas estudiadas, la actividad oxidativa parece conservada en el IE de sujetos con EPOC. Por su parte, la actividad de la vía glicolítica parece hallarse aumentada, y este aumento es proporcional a la gravedad de la EPOC. Estos resultados son probablemente la expresión del efecto combinado de diversos factores estructurales de carácter adaptativo. (AU)

Nasal polyp-derived superoxide anion: dose-dependent inhibition by nitric oxide and pathophysiological implications.

The epithelium of the paranasal sinuses produces nitric oxide (NO), which probably plays a major role in the nonspecific defense of these cavities through its bacteriostatic and cilia motility stimulation properties. Abundant eosinophils of nasal polyps potentially generate superoxide anion (O2-*), but NO and O2-* inactivate reciprocally. The purpose of the present work was to evaluate the relationship between NO concentrations and nasal polyp production of O2-*. Polyp fragments from 24 patients were studied using histological examination and lucigenin-enhanced chemiluminescence (to assess O2-* production). The effect of various concentrations of exogenous NO on chemiluminescent signals was assessed. Basal and phorbol ester-stimulated O2-* production varied largely among patients, but both were highly related to eosinophilic infiltration. A slow releasing NO donor DETA NONOate (DETA/NO NOC-18) dose dependently inhibited lucigenin-enhanced chemiluminescence from phorbol ester-stimulated polyp fragments, with an EC50 of 1.5 mM. The NO concentration in normal maxillary sinus was estimated about 10 ppm (i.e., 0.5 microM in aqueous phase) (Lundberg, et al. Nature Med 1995;1:370). Calculations revealed that the DETA NONOate 0.75 mM and 1.5 mM generate steady-state concentrations of NO of 0.5 microM and 2.5 microM, respectively. In conclusion, the NO concentration present in paranasal sinuses appears to partially suppress (approximately 20-40%) O2-* production from polyp eosinophils. Conversely, phagocytic-derived O2-* could contribute to decrease sinus NO concentration, further altering this natural local defense. Together, these events could participate in chronic inflammation and contribute to the pathophysiology of nasal polyps.

[The characteristics of the mechanical activity of the respiratory muscles during the diaphragmatic respiration technic]. / Características de la actividad mecánica de los músculos respiratorios durante la técnica de "respiración diafragmática".

UNLABELLED: Noteworthy among breathing training techniques is so-called diaphragmatic breathing. In spite of the technique's name, however, little is known of the functional characteristics of this ventilatory method. OBJECTIVE: To asses the mechanics of respiratory muscles, particularly diaphragm muscles, during diaphragmatic breathing in patients with severe chronic obstructive pulmonary disease (COPD). METHODS: Ventilatory pattern and respiratory pressures (abdominal [Pga], intrathoracic [Pes] and transdiaphragmatic [Pdi]) were studied in 10 patients with severe COPD in stable phase (age 69 +/- 6 years, FEV1 33 +/- 12% ref) at baseline and during deep breathing with spontaneous muscle recruitment (SMR) and during breathing training. Measurements were taken with the patient seated and in supine decubitus position. RESULTS: In seated position ventilatory pattern was similar with SMR and during breathing training. Mean Pdi during airflow, however, was greater during breathing training than with SMR (34.8 +/- 8.0 and 29.3 +/- 9.3 cmH2O, respectively, p < 0.05) for similar levels of Pes. Mechanical effectiveness of the diaphragm expressed as Vt/Pdi) was less during breathing training, however (36.1 +/- 10.4 and 49.5 +/- 15.8 cc/cmH2O, p < 0.05), with no changes in overall efficacy of respiratory muscles (Vt/Pes). In supine decubitus position, ventilatory patterns of SMR and breathing training were similar, although Vt and T1 were slightly higher in the latter (1,065 +/- 305 vs. 1,211 +/- 314 cc, p < 0.01; and 2.76 +/- 1.32 vs. 3.07 +/- 1.23 sec, p < 0.05). Pdi was also higher during breathing training (29.7 +/- 10.2 and 38.0 +/- 10.5 cmH2O, p < 0.05), although accompanied in this case by a higher Pes (21.2 +/- 7.5 to 26.4 +/- 8.4 cmH2O, p < 0.005). In supine decubitus position, the effectiveness of both diaphragm muscles and respiratory muscles overall was similar for both ventilatory modes. CONCLUSIONS: Breathing training truly involves greater use of the diaphragm, both in seated and supine decubitus positions. Breathing training does not provide greater ventilatory efficacy than SMR, however, in COPD patients.

[Obtaining samples of the human diaphragm during upper laparotomy. A structural analysis]. / Obtención de muestras del diafragma humano en el curso de laparotomía alta. Análisis estructural.

UNLABELLED: The diaphragm seems to undergo adaptive structural change in chronic obstructive pulmonary disease. The possibility of obtaining muscle specimens is limited, however, particularly when respiratory function is severely affected. OBJECTIVE: To assess the viability of a new technique for obtaining diaphragm muscle samples appropriate for structural assessment even from patients with severe functional change, and to study the size of fibers in relation to severity of disease. METHODS: Fifteen muscle specimens were obtained from patients (aged 57 +/- 15 years) by abdominal laparotomy. All had undergone full lung function testing. Muscle samples were taken during surgery using a new technique involving formation of a tobacco pouch with dome biopsy. The method had been previously validated in animal models. Later, the biopsies were processed to evaluate fiber proportions and sizes (ATPase dyes at different levels of pH). RESULTS: The 15 patients had a wide range of lung function results (FEV1 22-120% ref); 4 were severely affected (FEV1 < or = 50% ref). Nutritional status was normal in all cases; FEV1/FVC was 67 +/- 13%, RV was 134 +/- 55% ref, maximal mouth pressure (PImmax) was -75 +/- 27 cmH2O, transdiaphragmatic pressure (PIdimax) was 96 +/- 26 cmH2O, DLCO was 87 +/- 26% ref and PaO2 was 89 +/- 14 mmHg. We were able to obtain specimens valid for structural analysis from all patients with no complications. Light type I fibers predominated (54 +/- 9%) and size was normal overall (57 +/- 9 microns minimum diameter [Dm] atrophy index 195 +/- 243, and hypertrophy index 66 +/- 78), with no differences between the two fiber subtypes (Dm 58 +/- 8 microns for type I and 61 +/- 8 microns for type II). Overall size correlated inversely with static volumes (e.g. Dm with RV, r = -0.729, p < 0.01). CONCLUSIONS: The laparoscopic technique described is simple and safe for use in humans to obtain diaphragm muscle specimens that are valid for morphometric analysis, allowing us to enlarge the range of subjects that can be enrolled for this type of study. The fiber muscles studied are smaller when functional involvement is greater in chronic obstructive pulmonary disease.

FA-70, a novel selective and irreversible monoamine oxidase-A inhibitor: effect on monoamine metabolism in mouse cerebral cortex.

A series of indolealkylamine derivatives has been previously designed and evaluated with the aim of finding the most potent and selective novel monoamine oxidase (MAO) inhibitors to be used in the therapy of neurological and affective disorders. Among them, FA70, a 5-hydroxy-indolealkylamine derivative, has been characterized in vitro as a potent, irreversible, and mechanism-based inhibitor of the MAO-A isoform. The comparison with clorgyline, analyzed under the same experimental conditions, confirmed FA70 as the most potent MAO-A inhibitor. The ex vivo effect of FA70 on MAO activity in mouse cerebral cortex was similar to that observed in vitro, showing more efficacy than in peripheral tissues. The ex vivo effect of FA70 on amine metabolism also was evaluated after acute and chronic treatment, and the results showed that between both MAO isoforms, MAO-A is the only one responsible for monoamine metabolism in this region of the brain. The ex vivo effect of FA70 on dopamine content was correlated with the activation effect on tyrosine hydroxylase activity, the enzyme responsible for the regulation of the limiting step in catecholamine synthesis.

Características de la actividad mecánica de los músculos respiratorios durante la técnica de "respiración diafragmática" / Respiratory muscle mechanics during diaphragmatic breathing

Entre las técnicas de fisioterapia respiratoria destaca la llamada "respiración diafragmática" (RD). Sin embargo, y a pesar de su nombre, apenas se conocen las características funcionales de esta modalidad ventilatoria. Objetivo: Evaluar la actividad mecánica de los músculos respiratorios, especialmente del diafragma, durante la RD en pacientes con EPOC grave. Métodos: En 10 enfermos de esas características en fase estable (69 ñ 6 años, FEV1 33 ñ 12 por ciento ref), se estudiaron el patrón ventilatorio y las presiones respiratorias (abdominal o Pga, intratorácica o Pes y transdiafragmática o Pdi), tanto en situación basal como durante la respiración profunda con reclutamiento muscular espontáneo (RME) y la RD. El estudio se realizó tanto en sedestación (SED) como en decúbito supino (DEC). Resultados: En SED, el patrón ventilatorio no presentó diferencias entre RME y RD. En cambio, la Pdi media a volumen corriente fue mayor durante la RD (respectivamente, 29,3 ñ 9,3 y 34,8 ñ 8,0 cmH2O; p < 0,05), para valores similares de Pes. Sin embargo, la efectividad mecánica del diafragma (expresada por el Vt/Pdi), era menor en RD (49,5 ñ15,8 y 36,1 ñ 10,4 cm3/cmH2O; p < 0,05), sin cambios en la efectividad global de los músculos respiratorios (Vt/Pes). En DEC, los resultados fueron similares respecto del patrón ventilatorio para RME y RD, aunque Vt y TI fueron algo superiores en la segunda (respectivamente, 1.065 ñ 305 y 1.211 ñ 314 cm3, p < 0,01; y 2,76 ñ 1,32 frente a 3,07 ñ 1,23 s, p < 0,05). La Pdi también presentó un valor más alto en RD (29,7 ñ 10,2 y 38,0 ñ 10,5 cmH2O; p < 0,05), acompañado en esta ocasión por una Pes también superior (21,2 ñ 7,5 a 26,4 ñ 8,4 cmH2O; p < 0,005).Siguiendo con el DEC, la efectividad tanto del diafragma como de la globalidad de los músculos respiratorios resultó simil r para ambas modalidades ventilatorias. Conclusiones: La RD realmente corresponde a un mayor uso del diafragma, tanto en SED como en DEC. Sin embargo, en pacientes con EPOC grave esto no se traduce en una mayor efectividad en términos ventilatorios, si se compara con la RME. (AU)

Obtención de muestras del diafragma humano en el curso de laparotomía alta. Análisis estructural / Human diaphragm specimens obtained during high laparotomy. Structural analysis

El diafragma parece presentar fenómenos estructurales adaptativos en la EPOC. Sin embargo, existen limitaciones para la obtención de muestras musculares, sobre todo en enfermos con afectación funcional grave. Objetivo: Valorar la viabilidad de un nuevo modelo de obtención de muestras del diafragma, que permitiría el estudio estructural incluso en los pacientes mencionados, y estudiar si el tamaño de las fibras se relaciona con la gravedad de la enfermedad. Métodos: Se han estudiado 15 enfermos (de 57 ñ 15 años de edad), tributarios de laparotomía por proceso abdominal localizado. En todos ellos se efectuaron pruebas funcionales respiratorias completas. Las muestras musculares fueron obtenidas durante el acto quirúrgico, mediante una nueva técnica, con formación de "bolsa de tabaco" y biopsia en cúpula, validada previamente en modelos animales. Posteriormente, las biopsias fueron procesadas para evaluar las proporciones y tamaños fibrilares (tinción de ATPasa a diferentes pH). Resultados: Los 15 pacientes presentaban un amplio espectro funcional (FEV1 22-120 por ciento ref), que incluía 4 enfermos graves (FEV1 3/4 50 por ciento ref). Todos ellos se hallaban eunutridos y su función respiratoria mostraba un FEV1/FVC del 67 ñ 13 por ciento, RV 134 ñ 55 por ciento ref, y presiones máximas en la boca (PImmáx) de -75 ñ 27 cmH2O y transdiafragmática (PIdimáx) de 96 ñ 26 cmH2O, DLco 87 ñ 26 por ciento ref y PaO2 89 ñ 14 mmHg. En todos los pacientes fue posible la obtención de muestras válidas para el análisis estructural, con total ausencia de complicaciones. Las fibras presentaron un predominio ligero de las tipo I (54 ñ 9 por ciento), que mantenían un tamaño globalmente normal (57 ñ 9 µm de diámetro mínimo o Dm, índice de atrofia de 195 ñ 243 e índice de hipertrofia de 66 ñ 78), sin diferencias entre ambos subtipos fibrilares (Dm de 58 ñ 8 para las I y 61 ñ 8 µm para las II). Se observó una correlación inversa del tamaño global con los volúmenes estáticos (p. ej., Dm con RV, r = -0,729, p < 0,01). Conclusiones: La técnica laparoscópica descrita es sencilla y segura para su utilización en seres humanos, permitiendo obtener muestras del diafragma válidas para el estudio estructural. Esto permite ampliar el espectro de sujetos susceptibles de este tipo de estudios. Por otra parte, las fibras del músculo mencionado presentan un menor tamaño en relación con la gravedad de la afectación funcional asociada a la EPOC. (AU)

Neuroprotective aspects of a novel MAO-B inhibitor PF9601N.

PF9601N is an acetylenic tryptamine derivative devoid of amphetamine-like properties, that behaves as suicide MAO-B inhibitor more potent than l-deprenyl. It is highly selective towards MAO-B and it neuroprotects from the neurotoxicity induced in C57Bl/6 adult mice by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). PF9601N also shows in vitro antioxidant properties by inhibiting the dopamine autoxidation. A potential therapeutic use in Parkinson's disease treatment is proposed for this compound.

Involvement of Ca2+ in dopamine release in striatal rat slices by PF9601N and L-deprenyl.

Rat striatal slices were incubated 1 hour in Krebs buffer with carbogen by continuous perfusion. When both MAO-B inhibitors PF9601N and l-deprenyl were added in the incubation medium, at 200 microM concentration, a diminution in the dopamine content was observed. The decrease in dopamine content was partially calcium dependent and showed a different mechanism between both compounds. When 1 mM concentration EGTA was added at the Krebs incubation medium without calcium, dopamine content was partially recovered, being not affected in case of l-deprenyl. When 50 microM dantrolene (a calcium vesicular release inhibitor) was added in the Krebs incubation medium without calcium, dopamine was partially recovered for l-deprenyl, being not affected in case of PF9601N. These data indicate that dopamine release is extracellular calcium dependent in case of PF9601N, whereas l-deprenyl depends on calcium intracellular origin.

Evaluation of nasal prongs for estimating nasal flow.

Nasal prongs (NP) connected to a pressure transducer have been suggested as a useful alternative for measuring nasal flow in sleep apnea/hypopnea patients. However, flow measured with NP is expected to be nonlinear. The aim of the present study was to analyze and correct the nonlinearity of nasal flow measurements with NP (VNP). Nasal flow was simultaneously measured with a pneumotachograph (PNT; V) and (NP; VNP) in six healthy subjects during 60 s of breathing at different tidal volumes. Nonlinearity of VNP was assessed by fitting separately, for inspiration and expiration, a Rorher-model equation (VNP x K1 x V + K2 x V2). In addition, we fitted the data to a simpler nonlinear quadratic model (P = K x V2). The main findings were: (1) an excellent fit of the Rorher equation to measured data in all cases; (2) although differences in the Rorher equation coefficients between inspiration and expiration were observed, they were not statistically significant; (3) a substantial intersubject variability was found; and finally, (4) the square root of VNP acceptably fitted the nasal flow data measured by PNT (V) in most cases. We conclude that in order to quantitatively assess nasal flow with NP, data should be corrected for their nonlinear pressure-flow relationships and, that the square root of the flow signal measured with NP is the simplest method of correcting for the observed nonlinearity.

[Muscle relaxants in the morphometric study of the respiratory muscles in human beings]. / Relajantes musculares en el estudio morfométrico de los músculos respiratorios en seres humanos.

The morphological examination of respiratory muscle can be affected by muscular contraction following biopsy. Most morphometric studies of respiratory muscles, however, have been carried out without taking into account this factor, the effect of which can be reduced by using relaxants when taking samples. Objective. To examine the effect of using a relaxant in the morphometric analysis of muscle fibers. We examined 31 muscle samples from 7 patients. Immediately after removal, each pipe was divided in half. One was placed in an isotonic physiological solution and the other in a solution of curare 0.02%. Later, both samples were processed for morphometric study with ATP-ase, NADTH and PAS tincture. Morphological data recorded for the different types of fibers included measurement of minimum diameter (Dmin), atrophy and hypertrophy indices (AI and HI) and heterogeneity of distribution (SDDmin). The Dmin was smaller in fibers transported in a curare solution than in those transported in physiological solution (67 +/- 2 microns vs. 71 +/- microns, p < 0.05). The same was true of SDDmin (13 +/- 3 vs. 12 +/- 3, p < 0.05), HI (300 +/- 88 vs. 457 +/- 107, p < 0.05). Likewise, we found a similar direct correlation between size of fibers processed with physiological solution and those processed in curare (Dmin, r = 0.731, p < 0.001; HI, r = 0.827, p < 0.001; SDDmin, r = 0.636, p < 0.0001). The use of relaxants in processing muscle samples prevents contraction and should be used systematically in the morphological analysis of muscle fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Probable pentamidine-induced acute pancreatitis.

OBJECTIVE: To report a case of probable pentamidine-induced acute pancreatitis. CASE SUMMARY: A patient was hospitalized because of fever, dyspnea, and productive cough. Chest X-ray revealed diffuse alveolar infiltrates, and the examination of bronchoalveolar lavage demonstrated the presence of Pneumocystis carinii. Intravenous cotrimoxazole was administered but the patient's condition did not improve. As secondary leukopenia appeared, the treatment was changed to pentamidine isethionate 4 mg/kg/d i.v. On day 5 of this new therapy, the patient experienced abdominal pain, and both blood and urine amylase concentrations raised to 330 U/L and 3960 U/L, respectively. The patient died 48 hours later, and signs of acute pancreatitis were observed in necropsy. DISCUSSION: With reference to a classical method for estimating the probability of adverse drug reactions, a probable relationship between pentamidine therapy and acute pancreatitis was found in this patient. Furthermore, no alternative causes of pancreatitis were present. CONCLUSIONS: It is likely that pentamidine administration in our patient resulted in an acute episode of pancreatitis. Serum and urine amylase concentrations should be monitored in patients receiving this drug.

Separation and quantification of histamine and N tau-methylhistamine in brain extracts.

Histamine and its N tau-methyl derivative can be separated from perchloric acid extracts of rat brain by high performance liquid chromatography on a C18 column under isocratic conditions eluting with 0.1 M sodium phosphate buffer containing 0.19 mM sodium dodecyl sulphate and 25% methanol. Using electrochemical detection, histamine and N tau-methylhistamine can be detected at levels of less than 40 pg/microL tissue extract (less than 1 pmol). The retention times for histamine and N tau-methylhistamine were 15 min and 23 min, respectively, at a flow rate of 1.2 mL/min, and both compounds eluted as acceptably sharp peaks. The concentrations of histamine and N tau-methylhistamine in brain from seven-day-old rats were found to be very similar to those obtained by other analytical procedures.

Ultrasound for guidance of breast mass removal.

Hand-held sonomammography was used intraoperatively to localize 52 masses in 45 women in an out patient operating suite. All but five women had a positive X-ray mammogram. The ultrasound mammogram was able to identify all lesions. In 42 women studied by a preoperative ultrasound examination before the operating room procedure, all the masses were successfully identified. Precise localization was successfully performed in the operating room before sterile preparation in less than 10 minutes. Relocalization after incision in the sterile operating field was necessary in two cases. This technique requires no ionizing radiation and expedites outpatient surgical removal of the lesion. Of the 52 masses, there were 32 fibroadenomas, three carcinomas, three cysts, six cases of focal fibrous mastitis, and eight patients with focal fibrocystic disease. In patients with positive sonograms for nonpalpable masses, ultrasound localization is a fast, accurate alternative to X-ray needle placement.

The radiology of cardiac valve prostheses.

The radiographic findings associated with the complications of valve implantation are presented. Complementary roles of echocardiography and cine fluoroscopy in the recognition of complications associated with this procedure are emphasized. Identification of prosthetic valves and the knowledge of the modes of action of the various types of valves are stressed.