Utilization of elderly kidney donors (>70 years) does not affect graft survival in the medium term.

BACKGROUND: The need for organs for renal transplantation has encouraged the use of grafts from increasingly older donors. Earlier studies performed in Spain have shown the suitability of donors aged 60-65 years. In this single-center study, we evaluated our results using donors >70 years old. METHODS: We evaluated 401 primary transplantations performed from January 2000 to December 2009. Their initial immunosuppression was a tacrolimus-based (n = 324), cyclosporine-based (n = 70) or calcineurin inhibitor-free (n = 7) regimen patients. Recipients were classified according to the donors age: <50 (42.6%); 50-70 (39.7%) and >70 (17.5%) years. RESULTS: There were no differences in recipient or donor gender, time on dialysis, cold ischemia, delayed graft function, or acute rejection episodes. However, the mean age was higher among patients who received grafts from donors >70 years old; 42.5 ± 12.4 years for <50, 58.1 ± 8.2 years for 50-70, and 65.7 ± 7.2 years for >70; (P = .000). The serum creatinine at 12 months was increased according to the age of the donor; 1.4 ± 0.6, 1.8 ± 0.6, 70 and 1.7 ± 0.5 mg/dL, respectively (P = .001). The graft survival rates at 5 years were 81%, 74%, and 70%, respectively (P = .519). Upon multivariate analysis only HLA-DR mismatches, delayed graft function, and acute rejection episodes were associated with graft loss. Patient survival rates (86%) at 5 years were similar among recipients from donors aged 50-70 and >70 years, but higher (96%) for those who received a graft from a donor <50 years (P = .003). CONCLUSIONS: Nearly 20% of donors were >70 years old in our study. Their kidneys displayed excellent short-term outcomes.

Tratamiento de la anorexia urémica con acetato de megestrol / Treatment of uremic anorexia with megestrol acetate

Introducción: La anorexia es un trastorno frecuente en el enfermo tratado con hemodiálisis periódica, y factor contribuyente de la malnutrición. El objetivo del presente trabajo es comprobar la eficacia del acetato de megestrol, un estimulador del apetito utilizado en enfermos con cáncer, como tratamiento de la anorexia del enfermo sometido a diálisis. Material y métodos: En el año 2009, 16 enfermos de nuestra unidad de hemodiálisis, tres de ellos con diabetes mellitus, fueron tratados con acetato de megestrol (160 mg/día en dosis única), por anorexia definida según una escala Likert de apetito. La pauta y la dosis de diálisis no fueron modificadas durante el estudio. Resultados: Al tercer mes de tratamiento se objetivó, en el grupo total, un aumento del peso seco (60,8 frente a 58,9 kg; p <0,01), de la concentración de albúmina (4,02 frente a 3,8 g/dl; p <0,05), de la concentración de creatinina (9,73 frente a 8,26 mg/dl; p <0,01) y de la tasa de catabolismo proteico (1,24 frente a 0,97 g/kg/día; p <0,001). No hemos constatado variaciones significativas en la concentración de hemoglobina, dosis de eritropoyetina y concentración de lípidos. En un enfermo con diabetes mellitus hubo que aumentar la dosis de insulina y en otros 2 enfermos se detectó una hiperglucemia leve. El acetato de megestrol no suprimió la secreción de hormonas sexuales hipofisarias, pero en 3 de 10 enfermos estudiados se constató una inhibición de la secreción de corticotropina. La respuesta no fue homogénea: un enfermo no respondió y disminuyó su peso seco, en cinco el incremento de peso fue discreto (inferior a 1 kg) y en los 10 restantes la respuesta fue buena, con un incremento de peso seco que osciló entre 1,5 y 5,5 kg. Conclusiones: El acetato de megestrol puede mejorar el apetito y los parámetros nutricionales en enfermos tratados con hemodiálisis periódica que refieran anorexia. El acetato de megestrol puede inducir hiperglucemia e inhibir la secreción de corticotropina en algunos pacientes. Estos efectos secundarios deben ser valorados cuando se administre este tratamiento (AU)

Background: Anorexia is a common disorder in patients treated with regular haemodialysis and is a contributing factor to malnutrition. The aim of this study was to evaluate the effectiveness of megestrol acetate, an appetite stimulant used in cancer patients, as a treatment for anorexia in dialysis patients. Material and method: In 2009, 16 patients in our haemodialysis unit, three with diabetes mellitus, were treated with megestrol (160 mg/day single dose) for anorexia defined according to a Likert scale of appetite. The schedule and dialysis dose were not changed during the study. Results: In the third month of treatment there was, in the overall group, an increase in dry weight (60.8 vs 58.9 kg, P<.01), in albumin concentration (4.02 vs 3.8 g/dl, P<.05), in creatinine concentration (9.73 vs 8.26 mg/dl, P<.01), and protein catabolic rate (1.24 vs. 0.97 g/kg/day, P<.0001). Non-significant variations in the concentration of haemoglobin, erythropoietin dose, and lipid concentrations were found. One patient with diabetes mellitus had to increase the dose of insulin and two other patients suffered mild hyperglycaemia. Megestrol acetate did not suppress the secretion of pituitary sex hormones, but in 3 of 10 patients studied inhibition of ACTH secretion was found. The response was not homogeneous: one patient did not respond and reduced his dry weight, in 5 the weight gain was minimal (less than 1 kg) and in the remaining ten the response was good, with an increase in dry weight ranging between 1.5 and 5.5 kg. Conclusions: Megestrol acetate can improve appetite and nutritional parameters in patients treated with periodic haemodialysis who report anorexia. Megestrol acetate may induce hyperglycaemia and inhibit the secretion of ACTH in some patients. These side effects should be assessed when administering this treatment (AU)

[Treatment of uraemic anorexia with megestrol acetate]. / Tratamiento de la anorexia urémica con acetato de megestrol.

BACKGROUND: Anorexia is a common disorder in patients treated with regular haemodialysis and is a contributing factor to malnutrition. The aim of this study was to evaluate the effectiveness of megestrol acetate, an appetite stimulant used in cancer patients, as a treatment for anorexia in dialysis patients. MATERIAL AND METHOD: In 2009, 16 patients in our haemodialysis unit, three with diabetes mellitus, were treated with megestrol (160 mg/day single dose) for anorexia defined according to a Likert scale of appetite. The schedule and dialysis dose were not changed during the study. RESULTS: In the third month of treatment there was, in the overall group, an increase in dry weight (60.8 vs 58.9 kg, P<.01), in albumin concentration (4.02 vs 3.8 g/dl, P<.05), in creatinine concentration (9.73 vs 8.26 mg/dl, P<.01), and protein catabolic rate (1.24 vs. 0.97 g/kg/day, P<.0001). Non-significant variations in the concentration of haemoglobin, erythropoietin dose, and lipid concentrations were found. One patient with diabetes mellitus had to increase the dose of insulin and two other patients suffered mild hyperglycaemia. Megestrol acetate did not suppress the secretion of pituitary sex hormones, but in 3 of 10 patients studied was found inhibition of ACTH secretion. The response was not homogeneous: one patient did not respond and reduced his dry weight, in 5 the weight gain was minimal (less than 1 kg) and in the remaining ten the response was good, with an increase in dry weight ranging between 1.5 and 5.5 kg. CONCLUSIONS: Megestrol acetate can improve appetite and nutritional parameters in patients treated with periodic haemodialysis who report anorexia. Megestrol acetate may induce hyperglycaemia and inhibit the secretion of ACTH in some patients. These side effects should be assessed when administering this treatment.

Morbilidad en mujeres postmenopáusicas pobres / Morbidity in postmenopausal women with poverty

Background: Less favored social classes usually have more unhealthy life-styles and a more difficult access to Health Resources. Aim: To study the possible association between poverty and some common diseases, in a population of postmenopausal women. Material and Methods: Four hundred and forty nine poor women aged 56 ± 12 years and 776 consecutive women aged 53 ± 12 years, answered a personal interview about their lifestyles and medications used. Their medical records were reviewed and they were subjected to a complete physical examination, including weight and height measurement. A fasting blood sample was also obtained. Poverty was defined according to criteria of the Spanish National Institute of Statistics that is based on the income in Euros and the number of family members that share such income. Results: A higher proportion of poor women live in rural areas. They were shorter, had a higher weight and thus a higher body mass index, smoked less and drank less alcohol than their non-poor counterparts drink. The consumption of caffeine, the actual calcium intake and the physical activity during leisure time was similar in both groups. Compared with their counterparts, poor women had a higher prevalence of diabetes mellitus (15.9 and 10.1 percent respectively, p = < 0.01), obesity (44.2 and 24.3 percent respectively, p < 0.01) hypertension (24.3 and 16.4 percento respectively, p<0.01) and autoimmune rheumatic diseases (7.8 and 4.8 percent> respectively, p = 0.03). A multiple logistic regression model showed that obesity, hypertension, diabetes mellitus, smoking, alcohol consumption and living in rural areas, were independently associated to poverty. Conclusions: Poor postmenopausal women have a higher prevalence of diabetes mellitus, obesity, autoimmune rheumatic diseases and hypertension and lower frequency of smoking and alcohol consumption than their affluent counterparts do.

[Ventricular diastolic dysfunction in rheumatoid arthritis]. / Disfunciondiastólica ventricular izquierda en la artritis reumatoidea.

UNLABELLED: Rheumatoid arthritis ( RA) is a chronic and systemic articular inflammatory disease, often associated with cardiac manifestations. However, cardiac involvement in RA is not always symptomatic. Previous studies reported high mortality rates for RA and that it was dependent on concurrent heart dis-ease. Myocardial infarction and inflammation have been reported in about 2% of the patients in autopsy studies. The earliest deterioration in cardiac disease is in diastolic function. OBJECTIVE: the aim of this study is to evaluate the ventricular diastolic dysfunction in patients with RA and its relation with the duration of the disease. PATIENTS AND METHODS: Thirty-two RA patients who attended the rheumatology unit at Hospital Cordoba during 2004 participated in this study. A control group was formed by thirty two healthy adults of matched sex and age. RA was diagnosed according to 1987 ACR criteria. None of them had diabetes mellitus, systemic hypertension, chronic lung disease, congenital cardiac malformation, coronary artery disease, arrhytmia or valvular heart disease. Two-dimensional, M-mode, pulsed and color Doppler echocardiography were performed on all these subjects by the same examiner. Diastolic dysfunction was defined when the E/A ratio was <1 (E wave velocity decreased, A wave velocity increased) , and desaceleration time (DT) and isovolumic relaxation time (IRT) were prolonged. Ap-value < 0.05 was considered as significant. RESULTS: The mean ages were 48,38 11,08 for patients and 46,81 9,96 for the control group.There were no significant differences between age, sex, heart rate, and systolic and diastolic blood pressure between RA patients and controls. Higher proportion of RA patients had E/A ratio < 1compared with the controls ( p<00001). The mean IRT value was significantly longer than in controls ( 83,59 1 13,82 vs 74,41 i 15,14 p<0.01). There was no correlation between the duration of illness and E/A ratio and IRT ( p=0.70, p=0.13). CONCLUSION: Diastolic function was impaired in patients with RA. There was no relation between some of the parameters of ventricular diastolic function and disease duration. These findings suggest a subclinical myocardial involvement in RA patients.

[Clinical guidelines for the prevention of falls in elderly people]. / Guia de práctica clínica para la prevencion de caídas en el adulto mayor.

Demographic changes in our population are focusing on the health providers to prevent or minimize functional impairments resulting from the various chronic and multiple illnesses to which the elderly are prone. Because of that, we developed strategies that can help us to take decisions in order to identify the risk factors, and to prescribe preventive and rehabilitation programs. With this background, we organized an expert team to develop this guideline with evidence based on medicine methodology, and focus on the first level treatment prescribed by the general practitioner, with the participation of the health team and the support networks.

Polarized fluorescence microscopy of individual and many kinesin motors bound to axonemal microtubules.

Kinesin is a molecular motor that interacts with microtubules and uses the energy of ATP hydrolysis to produce force and movement in cells. To investigate the conformational changes associated with this mechanochemical energy conversion, we developed a fluorescence polarization microscope that allows us to obtain information on the orientation of single as well as many fluorophores. We attached either monofunctional or bifunctional fluorescent probes to the kinesin motor domain. Both types of labeled kinesins show anisotropic fluorescence signals when bound to axonemal microtubules, but the bifunctional probe is less mobile resulting in higher anisotropy. From the polarization experiments with the bifunctional probe, we determined the orientation of kinesin bound to microtubules in the presence of AMP-PNP and found close agreement with previous models derived from cryo-electron microscopy. We also compared the polarization anisotropy of monomeric and dimeric kinesin constructs bound to microtubules in the presence of AMP-PNP. Our results support models of mechanochemistry that require a state in which both motor domains of a kinesin dimer bind simultaneously with similar orientation with respect to the microtubule.

ADP-induced rocking of the kinesin motor domain revealed by single-molecule fluorescence polarization microscopy.

Kinesin is an ATP-driven molecular motor protein that moves processively along microtubules. Despite considerable research, the detailed mechanism of kinesin motion remains elusive. We applied an enhanced suite of single- and multiple-molecule fluorescence polarization microscopy assays to report the orientation and mobility of kinesin molecules bound to microtubules as a function of nucleotide state. In the presence of analogs of ATP, ADP-Pi or in the absence of nucleotide, the kinesin head maintains a rigid orientation. In the presence of ADP, the motor domain of kinesin, still bound to the microtubule, adopts a previously undescribed, highly mobile state. This state may be general to the chemomechanical cycle of motor proteins; in the case of kinesin, the transition from a highly mobile to a rigid state after ADP release may contribute to the generation of the 8 nm step.

Empleo del serodiagnóstico para detectar amebiasis invasiva en niños con disentería / Application of serodiagnosis to detect invasive amoebiasis in children with dysentery

La amebiasis es una parasitosis que afecta al 10 por ciento de la población mundial. Nueve de cada 10 infecciones son causadas por E. dispar, pero es diagnosticada y tratada como E. histolytica, por presentar quistes iguales. En cambio la infección por E. histolytica es invasiva, sintomática y presenta anticuerpos séricos específicos antiameba. La OMS recomienda el diagnóstico diferencial, dado que el tratamiento es innecesario si la infección es causada por E. dispar. Se evaluó la utilidad de las técnicas de la inmunofluorescencia indirecta (IFI) y el enzimoinmunoanálisis en fase sólida (ELISA) para el diagnóstico diferencial de estas infecciones. Se estudiaron 65 niños asistidos clasificados según clínica y examen coproparasitológico en: Grupo 1-A: asintomáticos, con coproparasitológicos negativos; Grupo 1-B: asintomáticos y con al menos un enteroparásito en el coproparasitológico; Grupo 2-A: con disentería, sospecha clínica de amebiasis y sin trofozoítos y/o quistes de E. histolytica / E. dispar en el coproparasitológico; Grupo 2-B: con disentería, sospecha clínica de amebiasis y con quistes y/o trofozoítos de E. histolytica / E. dispar en el coproparasitológico. Se realizaron exámenes coproparasitológicos directos y seriados y en muestras de suero se practicaron los inmuoensayos ELISA e IFI para la detección de anticuerpos específicos antiameba. Se observó que no hubo reactividad inespecífica con otras infecciones parasitarias y que la serología resultó reactiva cuando se hallaron trofozoítos hematófagos, patognomónicos de E. histolytica. La serorreactividad en los pacientes con quistes y/o trofozoítos no patognomónicos es fuertemente indicativa de una infección reciente. La probabilidad de tratarse de una infección remota es baja, ya que la proporción de anticuerpos específicos estudiada en 50 pacientes del grupo asintomático fue nula. Ambas técnicas presentaron resultados homólogos, a excepción de uno de los pacientes estudiados en quien, por serología, se pudo detectar una infección activa, pese a no haber sido detectada por el examen coproparasitológico. Se concluye que el empleo de técnicas de ELISA e IFI es una herramienta útil para mejorar el diagnóstico de invasión amebiana, permite aplicar una terapia acorde a las recomendaciones de la OMS y evita el tratamiento en infecciones por E. dispar (AU)

Empleo del serodiagnóstico para detectar amebiasis invasiva en niños con disentería / Application of serodiagnosis to detect invasive amoebiasis in children with dysentery

La amebiasis es una parasitosis que afecta al 10 por ciento de la población mundial. Nueve de cada 10 infecciones son causadas por E. dispar, pero es diagnosticada y tratada como E. histolytica, por presentar quistes iguales. En cambio la infección por E. histolytica es invasiva, sintomática y presenta anticuerpos séricos específicos antiameba. La OMS recomienda el diagnóstico diferencial, dado que el tratamiento es innecesario si la infección es causada por E. dispar. Se evaluó la utilidad de las técnicas de la inmunofluorescencia indirecta (IFI) y el enzimoinmunoanálisis en fase sólida (ELISA) para el diagnóstico diferencial de estas infecciones. Se estudiaron 65 niños asistidos clasificados según clínica y examen coproparasitológico en: Grupo 1-A: asintomáticos, con coproparasitológicos negativos; Grupo 1-B: asintomáticos y con al menos un enteroparásito en el coproparasitológico; Grupo 2-A: con disentería, sospecha clínica de amebiasis y sin trofozoítos y/o quistes de E. histolytica / E. dispar en el coproparasitológico; Grupo 2-B: con disentería, sospecha clínica de amebiasis y con quistes y/o trofozoítos de E. histolytica / E. dispar en el coproparasitológico. Se realizaron exámenes coproparasitológicos directos y seriados y en muestras de suero se practicaron los inmuoensayos ELISA e IFI para la detección de anticuerpos específicos antiameba. Se observó que no hubo reactividad inespecífica con otras infecciones parasitarias y que la serología resultó reactiva cuando se hallaron trofozoítos hematófagos, patognomónicos de E. histolytica. La serorreactividad en los pacientes con quistes y/o trofozoítos no patognomónicos es fuertemente indicativa de una infección reciente. La probabilidad de tratarse de una infección remota es baja, ya que la proporción de anticuerpos específicos estudiada en 50 pacientes del grupo asintomático fue nula. Ambas técnicas presentaron resultados homólogos, a excepción de uno de los pacientes estudiados en quien, por serología, se pudo detectar una infección activa, pese a no haber sido detectada por el examen coproparasitológico. Se concluye que el empleo de técnicas de ELISA e IFI es una herramienta útil para mejorar el diagnóstico de invasión amebiana, permite aplicar una terapia acorde a las recomendaciones de la OMS y evita el tratamiento en infecciones por E. dispar

Relationship between moiré patterns, tubulin shape, and microtubule polarity.

The polarity of microtubules is reflected in cryo-electron microscope images and in three-dimensional reconstructions [Chrétien et al., 1996: Structure 4:1031-1040; Sosa and Milligan, 1996: J. Mol. Biol. 260:743-755]. This paper shows how the directionality of the moiré patterns and the shape of the tubulin subunits are related. Microtubules observed by cryo-electron microscopy show an arrowhead moiré pattern that points toward the plus end of microtubules with a right-handed protofilament skew and toward the minus end of microtubules with a left-handed protofilament skew. On the other hand, three-dimensional reconstructions of microtubules observed from the plus end reveal a radial counterclockwise slew of the tubulin subunits. We show how these polar features are related and present unambiguous rules for determining the polarity on longitudinal and axial views of microtubules.

A model for the microtubule-Ncd motor protein complex obtained by cryo-electron microscopy and image analysis.

Kinesin motors convert chemical energy from ATP hydrolysis into unidirectional movement. To understand how kinesin motors bind to and move along microtubules, we fit the atomic structure of the motor domain of Ncd (a kinesin motor involved in meiosis and mitosis) into three-dimensional density maps of Ncd-microtubule complexes calculated by cryo-electron microscopy and image analysis. The model reveals that Ncd shares an extensive interaction surface with the microtubule, and that a portion of the binding site involves loops that contain conserved residues. In the Ncd dimer, the microtubule-bound motor domain makes intimate contact with its partner head, which is dissociated from the microtubule. This head-head interaction may be important in positioning the dissociated head to take a step to the next binding site on the microtubule protofilament.

Three different approaches for calculating the three-dimensional structure of microtubules decorated with kinesin motor domains.

We have used three different electron microscopy approaches to calculate three-dimensional maps of tubulin assemblies decorated with the motor domain of kinesin. The approaches used were: (1) Tilt series reconstruction of negatively stained tubulin sheets. (2) Back-projection reconstruction of microtubules in ice. (3) Helical reconstruction of microtubules in ice. The calculated maps show the overall configuration of the protofilaments and the interactions between the motor and the protofilaments at a resolution of 2-4 nm. The three methods revealed a similar binding configuration of the kinesin motor domain to the protofilament. We also found that seams can be present in potentially helical microtubules, limiting the use of helical reconstruction algorithms. Advantages and disadvantages of each of the three approaches are discussed.

Three-dimensional structure of ncd-decorated microtubules obtained by a back-projection method.

We have used cryo-electron microscopy and image analysis to obtain the three-dimensional (3D) structure of 11, 12, 14 and 15 protofilament microtubules decorated with the motor domain of ncd. To obtain the 3D maps, we developed a back-projection method that does not require a helical arrangement of the tubulin heterodimers. This method allows the calculation of 3D maps even when lattice discontinuities (seams) are present. The maps show that the microtubules we studied conform to a B-type lattice with one or more seams. In the presence of 5'-adenylim-idodiphosphate (AMP-PNP), the motor domain of ncd binds to the microtubule protofilament crest interacting with only one protofilament. Viewing the structures along the microtubule axis shows that the ncd motor domain and the tubulin are titled in opposite directions. We determined that a clockwise tilt of the tubulin subunits corresponds to a view from the minus end towards the plus end of the microtubule.

Cloning and expression of a murine fascin homolog from mouse brain.

The fascins are a widely distributed family of proteins that organize filamentous actin into bundles. We have cloned, sequenced, and expressed the murine homolog. Fascin is most abundant in brain and is found in other tissues including uterus and spleen. The deduced open reading frame encodes a protein of 493 amino acids with a molecular mass of 54,412 Da. Previous solubility problems with bacterially expressed fascins were overcome by producing the mouse protein as a fusion with Escherichia coli thioredoxin. A method for cleaving the fusion protein and for purifying active recombinant fascin is described. The N-terminal sequence and molecular mass estimated on SDS gels indicate that recombinant fascin is full-length. Two-dimensional gel electrophoresis suggests that recombinant fascin is post-translationally modified in a manner similar to that observed in mouse brain. Recombinant fascin and the fusion protein are recognized by monoclonal anti-fascin antibodies and will bundle rabbit skeletal muscle F-actin in vitro at a stoichiometry of 4.1:1 actin to fascin. Electron cryomicroscopy images show that the reconstituted bundles are highly ordered. However, their fine structure differs from that of echinoid fascin-actin bundles. This structural difference can be attributed to fascin.

Cloning of the beta cell high-affinity sulfonylurea receptor: a regulator of insulin secretion.

Sulfonylureas are a class of drugs widely used to promote insulin secretion in the treatment of non-insulin-dependent diabetes mellitus. These drugs interact with the sulfonylurea receptor of pancreatic beta cells and inhibit the conductance of adenosine triphosphate (ATP)-dependent potassium (KATP) channels. Cloning of complementary DNAs for the high-affinity sulfonylurea receptor indicates that it is a member of the ATP-binding cassette or traffic ATPase superfamily with multiple membrane-spanning domains and two nucleotide binding folds. The results suggest that the sulfonylurea receptor may sense changes in ATP and ADP concentration, affect KATP channel activity, and thereby modulate insulin release.

X-ray diffraction measurements of the extensibility of actin and myosin filaments in contracting muscle.

We have used a small angle scattering system assembled on the high flux multipole wiggler beam line at CHESS (Cornell) to make very accurate spacing measurements of certain meridional and layer-line reflections from contracting muscles. During isometric contraction, the actin 27.3 A reflection increases in spacing from its resting value by approximately 0.3%, and other actin reflections, including the 59 and 51 A off-meridional reflections, show corresponding changes in spacing. When tension is augmented or diminished by applying moderate speed length changes to a contracting muscle, changes in spacing in the range of 0.19-0.24% (when scaled to full isometric tension) can be seen. The larger difference between the resting and isometric spacings suggests either nonlinearity at low tension levels or the presence of a component related to activation itself. Myosin filaments also show similar increases in axial period during slow stretch, in addition to the well known larger change associated with activation. An actin spacing change of 0.25-0.3% can also be measured during a 2 ms time frame immediately after a quick release, showing that the elastic behavior is rapid. These observations of filament extensions totaling 2-3 nm per half-sarcomere may necessitate some significant revision of the interpretation of a number of mechanical experiments in muscle, in which it has usually been assumed that virtually all of the elasticity resides in the cross-bridges.

Ultrastructure of skeletal muscle fibers studied by a plunge quick freezing method: myofilament lengths.

We have set up a system to rapidly freeze muscle fibers during contraction to investigate by electron microscopy the ultrastructure of active muscles. Glycerinated fiber bundles of rabbit psoas muscles were frozen in conditions of rigor, relaxation, isometric contraction, and active shortening. Freezing was carried out by plunging the bundles into liquid ethane. The frozen bundles were then freeze-substituted, plastic-embedded, and sectioned for electron microscopic observation. X-ray diffraction patterns of the embedded bundles and optical diffraction patterns of the micrographs resemble the x-ray diffraction patterns of unfixed muscles, showing the ability of the method to preserve the muscle ultrastructure. In the optical diffraction patterns layer lines up to 1/5.9 nm-1 were observed. Using this method we have investigated the myofilament lengths and concluded that there are no major changes in length in either the actin or the myosin filaments under any of the conditions explored.

[The atrioventricular canal and vascular ring. The surgical treatment of a rare anatomical association]. / Canale atrioventricolare e anello vascolare. Trattamento chirurgico di una rara associazione anatomica.

We report the clinical and surgical data of 11 patients with atrioventricular canal and vascular ring. Down syndrome was present in 8 cases (72.7%); 8 patients were female (72.7%). Seven patients underwent, at the same time, correction of vascular ring and banding of the pulmonary artery with 4 death. Two children underwent correction of vascular ring and subsequent correction of atrioventricular canal without mortality. Two patients underwent correction of atrioventricular canal and subsequent correction of the vascular ring with one death. The mortality of the 6 patients operated after the age of 6 months was in measure of 16.6%. This association of malformations may be due to anomalies of neural crest and, although rare, should be particularly kept in mind referring to female patients with Down syndrome.

Cloning of cDNAs encoding human caldesmons.

Caldesmon (CDM) is a potential actomyosin regulatory protein found in smooth muscle and nonmuscle cells. Domain mapping and physical studies suggest that CDM is an elongated molecule with an N-terminal myosin/calmodulin-binding domain and a C-terminal tropomyosin/actin/calmodulin-binding domain separated by a 40-nm-long central helix. An 1100-nucleotide (nt) cDNA probe encoding the C terminus of avian caldesmon (aCDM) was used to screen a human aorta library and clone smooth-muscle and non-muscle CDM-encoding cDNAs (CDM). The human (h) smooth-muscle hCDM is 3050-3630 nt long, having variation in length in the 3'-untranslated region. The predicted hCDM protein has a high degree of identity, greater than 90%, to aCDM in the N- and C-terminal-binding domains. The central helical domain is more variable, but retains characteristic repeated peptides and an 'i, i + 4' acidic/basic amino acid (aa) motif found in aCDM which can form intra-helical salt bridges to stabilize the central helix. The predicted smooth-muscle protein is 793 aa long (93,262 Da) with a calculated pI of 5.75. As is the case for the chicken, nonmuscle hCDM is missing the central helical domain, 256 aa overall. Our nonmuscle clone is not full length, but the C-terminal end is identical to the smooth-muscle form. If the N-terminal domain is identical, as it is in the chicken, the predicted protein is 537 aa (62,558 Da). Examination of the 'junctions' at either end of the deleted central domain gives a clear indication of the splice sites and suggests that the nonmuscle form is generated by exon skipping.(ABSTRACT TRUNCATED AT 250 WORDS)