Processing strategies for smart electroconductive carbon nanotube-based bioceramic bone grafts.

Electroconductive bone grafts have been designed to control bone regeneration. Contrary to polymeric matrices, the translation of the carbon nanotube (CNT) electroconductivity into oxide ceramics is challenging due to the CNT oxidation during sintering. Sintering strategies involving reactive-bed pressureless sintering (RB + P) and hot-pressing (HP) were optimized towards prevention of CNT oxidation in glass/hydroxyapatite (HA) matrices. Both showed CNT retentions up to 80%, even at 1300 °C, yielding an increase of the electroconductivity in ten orders of magnitude relative to the matrix. The RB + P CNT compacts showed higher electroconductivity by ∼170% than the HP ones due to the lower damage to CNTs of the former route. Even so, highly reproducible conductivities with statistical variation below 5% and dense compacts up to 96% were only obtained by HP. The hot-pressed CNT compacts possessed no acute toxicity in a human osteoblastic cell line. A normal cellular adhesion and a marked orientation of the cell growth were observed over the CNT composites, with a proliferation/differentiation relationship favouring osteoblastic functional activity. These sintering strategies offer new insights into the sintering of electroconductive CNT containing bioactive ceramics with unlimited geometries for electrotherapy of the bone tissue.

In elderly women moderate hypercholesterolemia is associated to endothelial and microcirculatory impairments.

How cholesterol influences the microcirculation on aging subjects is not well known. This study evaluated moderate hypercholesterolemia effects in, treated or not, lean elderly women on brachial artery reactivity and microcirculatory function using venous occlusion plethysmography (VOP) and nailfold videocapillaroscopy (NVC). Patients (mean age 73 years) were divided into healthy elderly (HE, n=15), treated dyslipidemia with statins during at least 6 months (TDL, n=9) and dyslipidemia (DL, n=9, cholesterol, 257±11 and LDL-cholesterol, 157±24 mg/dl). Young, mean age 23 years, women (YC, n=24), served as controls. Laboratory and anthropometrical analysis, VOP peak forearm blood flow (FBF) during the reactive hyperemia response/baseline FBF (%HYPER) and peak FBF after 0.4 mg sublingual nitroglycerin/baseline FBF (%NITRO) were assessed. NVC capillary density and diameters, maximum red blood cell velocity (RBCV(max)) during reactive hyperemia/baseline RBCV and time to reach RBCV(max) were evaluated. Correlations between %HYPER, %NITRO and plasma cholesterol fractions were performed. Total and LDL-cholesterol were increased only in DL group. Capillary diameters were larger in elderly groups than YC. RBCV(max)/baseline RBCV was reduced in the DL group compared to HE, TDL and YC. %HYPER was lower in DL and normalized in TDL group. YC %HYPER was double of HE. %NITRO decreased from (HE=YC) to TDL and DL groups. There was a significant inverse correlation between LDL-cholesterol, non-HDL-cholesterol and %HYPER/% Nitro. In conclusion, moderate hypercholesterolemia reversibly impaired the vasodilatatory response in the microcirculation but the endothelial-independent vasodilator response to nitroglycerine remained irreversibly lower in healthy aged women.

Kaitoku seamount and the mystery cloud of 9 april 1984.

On 9 April 1984, commercial airlines enroute from Tokyo, Japan, to Anchorage, Alaska, reported an unusual mushroom-shaped cloud at about 38.5 degrees N, 146.0 degrees E. On 8 and 9 April the intensity of volcanism from Kaitoku Seamount (26.0 degrees N, 140.8 degrees E), as indicated by T-phase recordings on an array of ocean bottom hydrophones, reached a maximum level and then declined rapidly. An examination was made of the possible relation of the cloud to eruptions of Kaitoku through an analysis of pilot depositions, satellite photos, wind charts, signal strengths and spectra of known man-made underwater explosions, as well as ascent rates of volcanic plumes and cumulonimbus clouds.

Adhesion and wear behaviour of NCD coatings on Si3N4 by micro-abrasion tests.

Nanocrystalline diamond (NCD) coatings offer an excellent alternative for tribological applications, preserving most of the intrinsic mechanical properties of polycrystalline CVD diamond and adding to it an extreme surface smoothness. Silicon nitride (Si3N4) ceramics are reported to guarantee high adhesion levels to CVD microcrystalline diamond coatings, but the NCD adhesion to Si3N4 is not yet well established. Micro-abrasion tests are appropriate for evaluating the abrasive wear resistance of a given surface, but they also provide information on thin film/substrate interfacial resistance, i.e., film adhesion. In this study, a comparison is made between the behaviour of NCD films deposited by hot-filament chemical vapour deposition (HFCVD) and microwave plasma assisted chemical vapour deposition (MPCVD) techniques. Silicon nitride (Si3N4) ceramic discs were selected as substrates. The NCD depositions by HFCVD and MPCVD were carried out using H2-CH4 and H2-CH4-N2 gas mixtures, respectively. An adequate set of growth parameters was chosen for each CVD technique, resulting in NCD films having a final thickness of 5 microm. A micro-abrasion tribometer was used, with 3 microm diamond grit as the abrasive slurry element. Experiments were carried out at a constant rotational speed (80 r.p.m.) and by varying the applied load in the range of 0.25-0.75 N. The wear rate for MPCVD NCD (3.7 +/- 0.8 x 10(-5) mm3 N(-1) m(-1)) is compatible with those reported for microcrystalline CVD diamond. The HFCVD films displayed poorer adhesion to the Si3N4 ceramic substrates than the MPCVD ones. However, the HFCVD films show better wear resistance as a result of their higher crystallinity according to the UV Raman data, despite evidencing premature adhesion failure.

Sirolimus: efficacy in liver transplant patients with nephrotoxicity and renal insufficiency.

Nephrotoxicity is a complication of patients undergoing orthotopic liver transplantation. Herein we present several factors that play an important role in this complication.

Ocorrência de distúrbios de condução e implante de marca-passo definitivo em pacientes submetidos a TAVI com abordagem minimalista / Occurrence of conduction disorders and permanent pacemaker implantation in patients undergoing TAVI with a minimalist approach

INTRODUÇÃO: O surgimento de distúrbios de condução e a necessidade de implante de marca-passo (MP) definitivo estão entre as complicações mais comuns relacionadas ao TAVI. Na aplicação do TAVI minimalista - em que se objetiva alta hospitalar oportuna < 48 horas - tais complicações são de central importância, e sua ocorrência deve ser monitorada sistematicamente. OBJETIVO: Avaliar a prevalência de alterações eletrocardiográficas sabidamente preditoras de distúrbios de condução após TAVI e a incidência de MP definitivo em até 30 dias após o procedimento, em pacientes (pctes) não-selecionados submetidos a TAVI minimalista em um hospital terciário do SUS. MÉTODOS: Estudo observacional e prospectivo, com inclusão de pctes consecutivos submetidos a TAVI minimalista no período de Set/2020 a Jan/2022, com análise do ECG antes e após a TAVI conforme protocolo institucional. Verificado a presença de alterações de ritmo e bloqueios atrioventriculares (BAV) e intraventriculares e a indicação de MP definitivo durante a internação e um mês após a alta hospitalar. RESULTADOS: Foram avaliados 50 pctes, com média de idade de 79,2 anos, com STS médio de 2,64% e 20 (40%) mulheres. Próteses balão-expansíveis foram utilizadas mais frequentemente (76%). O ritmo e distúrbios de condução antes da TAVI encontrados foram: • Ritmo sinusal: 41 (82%) • Fibrilação atrial: 12 (24%) • BAV 1 grau: 14 (28%) • Bloqueio de ramo direito: 3 (6%) • Bloqueio de ramo esquerdo: 7 (14%) • Ritmo de MP: 4 (8%) A ocorrência de bradiarritmias que justificassem monitorização estendida e vigilância intra-hospitalar por ao menos 24 horas ocorreu em 7 (14%) pcts, sendo: • Bloqueio atrioventricular total: 1 (2,5%) • Bloqueio atrioventricular avançado: 1 (2,5%) • Fibrilação atrial de baixa resposta ventricular: 2 (5%) • Ritmo juncional: 2 (5%) • Bradicardia sinusal e distúrbio de condução intraventricular: 1 (2,5%) Houve indicação de MP definitivo para 1 (2,5%) pcte. Não houve reinternação devido a distúrbios de condução ou implante de MP até 30 dias após a TAVI. CONCLUSÃO: Em nossa experiência, poucos pctes submetidos a TAVI com estratégia minimalista apresentaram distúrbios de condução necessitaram postergar a alta hospitalar. Apenas um paciente requereu implante de MP definitivo. A aplicação de protocolo institucional com alta hospitalar oportuna (<48h) não esteve relacionada à maior risco de distúrbios de condução em curto prazo (30 dias).

The High performance of nanocrystalline CVD diamond coated hip joints in wear simulator test.

The superior biotribological performance of nanocrystalline diamond (NCD) coatings grown by a chemical vapor deposition (CVD) method was already shown to demonstrate high wear resistance in ball on plate experiments under physiological liquid lubrication. However, tests with a close-to-real approach were missing and this constitutes the aim of the present work. Hip joint wear simulator tests were performed with cups and heads made of silicon nitride coated with NCD of ~10 µm in thickness. Five million testing cycles (Mc) were run, which represent nearly five years of hip joint implant activity in a patient. For the wear analysis, gravimetry, profilometry, scanning electron microscopy and Raman spectroscopy techniques were used. After 0.5 Mc of wear test, truncation of the protruded regions of the NCD film happened as a result of a fine-scale abrasive wear mechanism, evolving to extensive plateau regions and highly polished surface condition (Ra<10nm). Such surface modification took place without any catastrophic features as cracking, grain pullouts or delamination of the coatings. A steady state volumetric wear rate of 0.02 mm(3)/Mc, equivalent to a linear wear of 0.27 µm/Mc favorably compares with the best performance reported in the literature for the fourth generation alumina ceramic (0.05 mm(3)/Mc). Also, squeaking, quite common phenomenon in hard-on-hard systems, was absent in the present all-NCD system.

Microstructure, toughness and flexural strength of self-reinforced silicon nitride ceramics doped with yttrium oxide and ytterbium oxide.

Self-reinforced silicon nitride ceramics with additions of either yttrium oxide or ytterbium oxide have been investigated at room temperature after various processing heat treatments. Devitrification of the intergranular phase in these materials is very sensitive to the heat treatment used during processing and does not necessarily improve their strength and toughness. Hot-pressed ceramics without a subsequent devitrification heat treatment were the strongest. The ytterbium oxide-doped silicon nitride ceramics were consistently tougher, but less strong, than the yttrium oxide-doped silicon nitride ceramics. In all the ceramics examined, the fracture toughness showed evidence for R-curve behaviour. This was most significant in pressureless sintered ytterbium oxide-doped silicon nitride ceramics. A number of toughening mechanisms, including crack deflection, bridging, and fibre-like grain pull-out, were observed during microstructural analysis of the ceramics. In common with other silicon nitride-based ceramics, thin amorphous films were found at the grain boundaries in each of the ceramics examined. Arrays of dislocations left in the elongated silicon nitride grains after processing were found to belong to the {101;0}<0001> primary slip system.

Synthesis and hypolipidemic activity of N-phthalimidomethyl tetra-O-acyl-alpha-D-mannopyranosides.

A facile synthesis of anomerically pure phthalimidomethyl 2,3,4,6-tetra-O-acetyl- and phthalimidomethyl 2,3-di-O-acetyl-4,6-di-O-benzoyl-alpha-D-mannopyranosides (6 and 9b) starting from N-hydroxymethylphthalimide and tri-O-acetyl-D-glucal is described. Compounds 3, 6, 8, 9a and 9b have been tested for their hypolipidemic activity in mice. All these compound showed significant reduction of plasma cholesterol and triglyceride levels. Compound 9b has been found to possess the highest activity.

Oxidative stress of liver in hamsters infected with Leishmania (L.) chagasi.

Oxidative stress as a mediator of hepatic tissue damage concurrent with Leishmania (L.) chagasi infection was investigated. Chemiluminescence in liver supernatant of hamsters infected with Leishmania (L.) chagasi showed a ratio of 1.53/ mg protein and 2.10/liver weight 90 days after infection when compared with the control. The malondialdehyde (MDA) levels also increased significantly both with and without addition of Fe3+/ascorbic acid in the reaction mixture, with a ratio of 2.12 and 1.55/mg protein or 2.91 and 2.12/liver weight, respectively. The parasite burden in the spleen, as a measure of infection severity, was 9.1+/-1.33 x 10(8) parasites/organ. On the 10th day of infection, the chemiluminescence also was significantly higher in infected hamsters than in the controls (ratio = 1.36/mg protein or 1.34/liver weight); however, the MDA levels were not different from those of controls. After 90 days of infection, significant correlations were observed between chemiluminescence and MDA concentration with and without the presence of Fe3+/ascorbic acid (r = 0.54, P = 0.0001; r = 0.56, P = 0.0001; respectively). The high infection/control ratio of both chemiluminescence and MDA concentration and the significant correlation between those events strongly indicate the occurrence of oxidative stress and lipid peroxidation as a mechanism of liver damage in cases of chronic infection by L. chagasi. The significant increase in chemiluminescence at 10 days of infection demonstrates that oxidative stress occurs very early, first consuming the antioxidants and then inducing lipid peroxidative damage later in the chronic stage of this disease.

Total gastrectomy for gastric cancer in elderly patients.

BACKGROUND/AIMS: The increased average life expectancy and the changing patterns in gastric carcinoma have resulted in a considerable rise in the number of older patients requiring total gastrectomy. Results of total gastrectomy for gastric cancer in elderly patients are presented. METHODOLOGY: Between January 1987 and December 1996, 115 patients underwent total gastrectomy for gastric adenocarcinoma. At the time of surgery, 25 (21.8%) patients were older than 70 years. The results achieved in these patients were compared with those observed in 90 younger ones. RESULTS: The hospital mortality and morbidity rates for the elderly patients were 16% and 56%, respectively; for the younger ones they were 3.3% and 30%, respectively. No difference was seen between the two age groups concerning the average post-operative hospital stay. CONCLUSIONS: In our series, age was a major determinant with respect to post-operative morbidity and mortality. However, age alone could not be clearly defined as a determining risk factor considering that the accompanying illness and preexisting factors predispose for poor prognosis.

Total gastrectomy for gastric adenocarcinoma. Analysis of 115 consecutive patients.

BACKGROUND/AIMS: There was a tendency to use more extensive operations for the treatment of gastric cancer during the last decade particularly in Europe. This retrospective study was carried out to review our recent experience with total gastrectomy for gastric adenocarcinoma. METHODOLOGY: One hundred and fifteen patients treated for gastric cancer by total gastrectomy from 1987 to 1996 were analyzed. At the time of surgery 22.3% of patients were older than 70 years of age. RESULTS: Fifty eight cancers (50.4%) were located in the distal third of the stomach, forty-seven (41%) were smaller than 6 cm and seventy-one (61.7%) were of the diffuse type. In 74.9% the tumor had penetrated through the serosa. The mortality and morbidity rates were 6.1% and 35.1% respectively. Age was a major determining factor with respect to hospital mortality and post-operative complications. CONCLUSIONS: Irrespective of personal attitudes, gastrectomy does not have to be total to be curative, and many total gastrectomies performed in Western countries with "curative intent" are noncurative procedures. Nevertheless, to achieve a curative oncologic resection, total gastrectomy is required with growing frequency.

[Aedes (Stegomyia) aegypti L. and associated culicidae fauna in a urban area of southern Brazil]. / Aedes (Stegomyia) aegypti L. e a culicideofauna associada em área urbana da região sul, Brasil.

Some aspects of the ecology of eleven species of Culicidae that were found breeding in recipients in an urban area of Southern Brazil are presented. A great variety of recipients were listed as efficient breeding sites. Apparently Aedes aegypti has been recently introduced into the region and was limited to two areas of the city. Culex quinquefasciatus, Cx. coronator, Ae. aegypti, Ae. fluviatilis e Limatus durhamii were the predominant species.

[Long-term results of modified supra-pyloric gastrectomy in the treatment of gastric ulcer]. / Résultats à long terme de la gastrectomie supra-pylorique modifiée dans le traitement de l'ulcère gastrique.

An original technique for supra-pyloric gastrectomy with preservation of sphincter function of the pylorus was performed in a series of 26 patients with benign ulcer of the lesser curvature. The results were evaluated 3-10 years after the operation. Twenty-five patients obtained a satisfactory results (visick grades I or II). The rate of gastric emptying was tested with a meal labelled with TC 99 in 17 patients. Only one patient suffered from gastric stasis. It is concluded that supra-pyloric gastrectomy with preservation of the pylorus has a place in the treatment of benign ulcers of the lesser curvature.

[Perforations of the small intestine in closed injuries of the abdomen. Apropos of 63 cases]. / Les perforations du grêle au cours des traumatismes fermés de l'abdomen. A propos de 63 observations.

The records of 63 patients with small bowel perforation after blunt abdominal trauma admitted to the Department of Surgical Pathology, University Hospital of Coimbra, from 1965 to 1981, have been reviewed to establish patterns of injury and to discuss their pathogenesis and operative management. The authors believe that injuries to the small intestine following blunt abdominal trauma are more common than is generally appreciated. Proper treatment is frequently delayed because these injuries are not recognized promptly. Factors contributing to this delay are the trivial nature of some of the responsible accidents and the often negative results of diagnostic aids.

Novel electrochemical method of fast and reproducible fabrication of metallic nanoelectrodes.

A novel electrochemical wire etching method of fabrication of ultrasharp nanoelectrodes is reported. Tungsten wires can be sharpened to less than 10 nm tip radius in a reproducible manner in less than 1 min by using controllable hydrodynamic electrolyte flow combined with optimized electrochemical etching parameters. The method relies on the variations of the electric field at the surface of a metal wire, while the electrolyte solution is in motion, rather than on the ionic gradient generated in a static solution.

Multifunctional carbon nanotube/bioceramics modulate the directional growth and activity of osteoblastic cells.

Biomaterials can still be reinvented to become simple and universal bone regeneration solutions. Following this roadmap, a bone graft of carbon nanotube (CNT)/glass/hydroxyapatite (HA) with controlled CNT agglomeration state was designed with multifunctionalities able to stimulate the bone cell phenotype. The preparation route, the mechanical and electrical behavior and the in vitro profiles of degradation and osteocompatibility were described. A non-destructive dynamic route was found to have a higher influence than the Diels-Alder functionalization one on controlling the CNT agglomerate state in the ceramic-matrix composite. Biologically safe CNT agglomerates, with diameter sizes below 3 microm homogenously distributed, were obtained in non-functionalized and functionalized composites. Yet, the lowest CNT damage and the highest mechanical and electrical properties were found for the non-functionalized materials. Even though that these composites present higher degradation rate at pH:3 than the ceramic matrix, the CNT agglomerates are released with safe diameter sizes. Also, non-functionalized composites allowed cellular adhesion and modulated the orientation of the cell growth, with a proliferation/differentiation relationship favoring osteoblastic functional activity. Findings offer further contributions for bone tissue engineering by showing that multifunctional bone grafts with high electroconductivity, and integrating CNT agglomerates with maximized interfacing area, allow the in situ control of bone cell functions.

Carbon nanotube-based bioceramic grafts for electrotherapy of bone.

Bone complexity demands the engineering of new scaffolding solutions for its reconstructive surgery. Emerging bone grafts should offer not only mechanical support but also functional properties to explore innovative bone therapies. Following this, ceramic bone grafts of Glass/hydroxyapatite (HA) reinforced with conductive carbon nanotubes (CNTs) - CNT/Glass/HA - were prepared for bone electrotherapy purposes. Computer-aided 3D microstructural reconstructions and TEM analysis of CNT/Glass/HA composites provided details on the CNT 3D network and further correlation to their functional properties. CNTs are arranged as sub-micrometric sized ropes bridging homogenously distributed ellipsoid-shaped agglomerates. This arrangement yielded composites with a percolation threshold of pc=1.5vol.%. At 4.4vol.% of CNTs, thermal and electrical conductivities of 1.5W·m(-1)·K(-1) and 55S·m(-1), respectively, were obtained, matching relevant requisites in electrical stimulation protocols. While the former avoids bone damaging from Joule's heat generation, the latter might allow the confinement of external electrical fields through the conductive material if used for in vivo electrical stimulation. Moreover, the electrically conductive bone grafts have better mechanical properties than those of the natural cortical bone. Overall, these highly conductive materials with controlled size CNT agglomerates might accelerate bone bonding and maximize the delivery of electrical stimulation during electrotherapy practices.