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1.
Arch Orthop Trauma Surg ; 144(6): 2547-2552, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38777907

RESUMO

INTRODUCTION: Pathological destruction of the axis vertebra leads to a highly unstable condition in an upper cervical spine. As surgical resection and anatomical reconstruction of the second cervical vertebrae represents a life threatening procedure, less radical approaches are preferred and only few cases of C2 prosthesis are described in literature. CASE DESCRIPTION: The focus of this case report is a 21-year-old man with a pathological fracture of C2 managed primarily surgically with the C1-C3 dorsal fusion. Due to the progression of giant cell tumor and destruction of the axis vertebra, C2 prosthesis through anterior approach and dorsal occipito-cervical fusion C0-C4 were performed. Postoperative infection was managed surgically with a 2-staged dorsal debridement, ostheosynthesis material change and autologous bone graft. After a 4 week-intravenous therapy with the ceftriaxone in combination with the amoxicillin/clavulanate, followed by 12 week per oral therapy with amoxicillin/clavulanate in combination with ciprofloxacin, the complete recovery of the infection was achieved. Radiotherapy was initiated 2 months after the last revision surgery and the patient showed a good clinical outcome with stable construct at a 1 year follow-up. A review of literature of all reported C2 prosthesis cases was performed CONCLUSION: C2 prosthesis allows a more radical resection in pathological processes involving the axis vertebra. Combined with the posterior fusion, immediate stability is achieved. Anterior surgical approach is through a highly unsterile oral environment which presents a high-risk of postoperative infection.


Assuntos
Fraturas da Coluna Vertebral , Fusão Vertebral , Humanos , Masculino , Fusão Vertebral/métodos , Adulto Jovem , Fraturas da Coluna Vertebral/cirurgia , Vértebras Cervicais/cirurgia , Vértebras Cervicais/lesões , Vértebra Cervical Áxis/cirurgia , Vértebra Cervical Áxis/lesões , Fraturas Espontâneas/cirurgia , Fraturas Espontâneas/etiologia , Implantação de Prótese/métodos , Neoplasias da Coluna Vertebral/cirurgia
2.
Skeletal Radiol ; 49(11): 1819-1827, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32524168

RESUMO

OBJECTIVE: To determine diagnostic confidence and inter-observer/intra-observer agreement in differentiating epidural fibrosis from disc herniation and lumbar spinal stenosis parameters on magnetic resonance images (MRI) in postoperative lumbar spines with (Gad-MRI) and without (unenhanced MRI) intravenous gadolinium-based contrast agent. SUBJECTS AND METHODS: N = 124 lumbar spine MRI examinations of four groups were included: 1-6 months, 7-18 months, 19-36 months, more than 37 months between lumbar spine surgery and imaging. Two radiologists evaluated Gad-MRI and unenhanced MRI: diagnostic confidence was determined as confident or unconfident. Inter-observer and intra-observer agreement were assessed in differentiating epidural fibrosis from disc herniation and for lumbar spinal stenosis parameters on MRI. Fisher's exact test and Cohen's kappa served for statistics. RESULTS: Diagnostic confidence in differentiating epidural fibrosis from disc herniation was significantly higher on Gad-MR images compared with unenhanced MRI at 1-18 months for observer 1 and at 1-6 months postoperatively for observer 2 (p values: 0.01-0.025). Inter-observer agreement at 1-6 months postoperatively for identification of epidural fibrosis was higher on Gad-MRI (kappa values: 0.53 versus 0.24). Inter-observer and intra-observer agreement for identification of disc herniation and for assessment of lumbar spinal stenosis parameters revealed inconsistent data, without a trend for higher inter-observer or intra-observer agreement on Gad-MRI compared with unenhanced MRI (kappa values: 0.17-0.75). CONCLUSION: Gad-MR images compared with unenhanced MRI improved diagnostic confidence and agreement in differentiating epidural fibrosis from disc herniation for both observers in the first 6 months and for one observer in the first 18 months after lumbar spine surgery. After 18 months, Gad-MR images compared with unenhanced MRI did neither improve confidence nor agreement.


Assuntos
Deslocamento do Disco Intervertebral , Imageamento por Ressonância Magnética , Fibrose , Humanos , Deslocamento do Disco Intervertebral/diagnóstico por imagem , Deslocamento do Disco Intervertebral/patologia , Deslocamento do Disco Intervertebral/cirurgia , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/patologia , Vértebras Lombares/cirurgia , Variações Dependentes do Observador
3.
Eur Spine J ; 23(6): 1332-8, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24197481

RESUMO

PURPOSE: The SWISSspine registry (SSR) was launched in 2005 to assess the safety and effectiveness of balloon kyphoplasty (BKP). In the meantime, repeated reports on high rates of adjacent vertebral fractures (ASF) after BKP of vertebral insufficiency fractures were published. The causes for ASF and their risk factors are still under debate. The purpose of this study was to report the incidence and potential risk factors of ASF within the SSR dataset. METHODS: The SSR data points are collected perioperatively and during follow-ups, with surgeon- and patient-based information. All patients documented with a monosegmental osteoporotic vertebral insufficiency fracture between March 2005 and May 2012 were included in the study. The incidence of ASF, significant associations with co-variates (patient age, gender, fracture location, cement volume, preoperative segmental kyphosis, extent of kyphosis correction, and individual co-morbidities) and influence on quality of life (EQ-5D) and back pain (VAS) were analyzed. RESULTS: A total of 375 patients with a mean follow-up of 3.6 months was included. ASF were found in 9.9 % (n = 37) and occurred on average 2.8 months postoperatively. Preoperative segmental kyphosis >30° (p = 0.026), and rheumatoid arthritis (p = 0.038) and cardiovascular disease (p = 0.047) were significantly associated with ASF. Furthermore, patients with ASF had significantly higher back pain at the final follow-up (p = 0.001). No further significant associations between the studied co-variates and ASF were seen in the adjusted analysis. CONCLUSIONS: The findings suggest that patients with a preoperative segmental kyphosis >30° or patients with co-morbidities like rheumatoid arthritis and a cardiovascular disease are at high risk of ASF within 6 months after the index surgery. In case of an ASF event, back pain levels are significantly increased. LEVEL OF EVIDENCE: IV.


Assuntos
Cifoplastia/efeitos adversos , Fraturas por Osteoporose/cirurgia , Fraturas da Coluna Vertebral/epidemiologia , Idoso , Idoso de 80 Anos ou mais , Artrite Reumatoide/epidemiologia , Dor nas Costas/epidemiologia , Cimentos Ósseos/uso terapêutico , Doenças Cardiovasculares/epidemiologia , Feminino , Fraturas por Compressão/epidemiologia , Fraturas por Compressão/cirurgia , Humanos , Incidência , Cifoplastia/métodos , Cifose/epidemiologia , Cifose/cirurgia , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Fraturas por Osteoporose/epidemiologia , Sistema de Registros , Fatores de Risco , Suíça/epidemiologia
4.
Artigo em Inglês | MEDLINE | ID: mdl-37022449

RESUMO

In this work the nonlinear behavior of layered SAW resonators is studied with the help of Finite Element (FE) computations. The full calculations depend strongly on the availability of accurate tensor data. While there are accurate material data for linear computations, the complete sets of higher-order material constants, needed for nonlinear simulations, are still not available for relevant materials. To overcome this problem, scaling factors were used for each available nonlinear tensor. The approach here considers piezoelectricity, dielectricity, eletrostriction and elasticity constants up to fourth order. These factors act as a phenomenological estimate for incomplete tensor data. Since no set of fourth order material constants for LiTaO3 is available, an isotropic approximation for the fourth order elastic constants was applied. As a result, it was found that the fourth order elastic tensor is dominated by one fourth order Lamé constant. With the help of the FE model, derived in two different, but equivalent ways, we investigate the nonlinear behavior of a SAW resonator with a layered material stack. The focus was set to third order nonlinearity. Accordingly, the modeling approach is validated using measurements of third order effects in test resonators. In addition, the acoustic field distribution is analyzed.

5.
J Insect Sci ; 12: 109, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23438104

RESUMO

The causes of thermal tolerance limits in animals are controversial. In many aquatic species, it is thought that the inability to deliver sufficient oxygen at high temperatures is more critical than impairment of molecular functions of the mitochondria. However, terrestrial insects utilize a tracheal system, and the concept of a mismatch between metabolic demand and circulatory performance might not apply to them. Using thermo-limit respirometry, it has been shown earlier in Drosophila melanogaster that CO(2) release rates at temperatures above the upper thermal limit (CT(max)) exceed the rate at CT(max). The nature of this post-CT(max), or "post-mortal" peak, is unknown. Either its source is increased aerobic mitochondrial respiration (hyperthermic overdrive), or an anaerobic process such as liberation of stored CO(2) from the hemolymph. The post-mortal peak of CO(2) release was found to be oxygen dependent. As the rate of CO(2) emission is a conservative indicator of rate of O(2) consumption, aerobic flux at the thermal limit is submaximal, which contradicts the theory that oxygen availability limits metabolic activity at high temperatures in insects. Consequently, the tracheal system should be capable of delivering sufficient oxygen for aerobic activity of the mitochondria at and above Ct(max).


Assuntos
Dióxido de Carbono/metabolismo , Drosophila melanogaster/fisiologia , Oxigênio/metabolismo , Aclimatação , Aerobiose , Animais , Metabolismo Basal , Feminino , Masculino , Fenômenos Fisiológicos Respiratórios , Temperatura
6.
Surg Neurol Int ; 12: 496, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34754546

RESUMO

BACKGROUND: While pyogenic spondylodiscitis due to Gram-positive aerobic bacteria and its treatment is well known, spondylodiscitis caused by anaerobic Gram-negative pathogen is rare. In particular, the spondylodiscitis caused by Veillonella species is an absolute rarity. Thus no established management recommendations exist. CASE DESCRIPTION: A case report of a 79-year-old man with spondylodiscitis caused by Veillonella parvula with intramuscular abscess collection managed conservatively with stand-alone antibiotic therapy without a spinal stabilization procedure. A review of literature of all reported spondylodiscitis caused by Veillonella species was performed. After 3 week-intravenous therapy with the ceftriaxone in combination with the metronidazole followed by 3 weeks per oral therapy with amoxicillin/clavulanate, the complete recovery of the patient with the V. parvula infection was achieved. CONCLUSION: Treatment of the spondylodiscitis caused by Veillonella species should contain a beta-lactam with beta-lactamase inhibitor or third-generation cephalosporine. Six weeks of treatment seem to be sufficient for the complete recovery of the patient.

7.
Int J Cancer ; 124(12): 2899-904, 2009 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-19230026

RESUMO

Molecular markers reliably predicting failure or success of Bacillus Calmette-Guérin (BCG) in the treatment of nonmuscle-invasive urothelial bladder cancer (NMIBC) are lacking. The aim of our study was to evaluate the value of cytology and chromosomal aberrations detected by fluorescence in situ hybridization (FISH) in predicting failure to BCG therapy. Sixty-eight patients with NMIBC were prospectively recruited. Bladder washings collected before and after BCG instillation were analyzed by conventional cytology and by multitarget FISH assay (UroVysion, Abbott/Vysis, Des Plaines, IL) for aberrations of chromosomes 3, 7, 17 and 9p21. Persistent and recurrent bladder cancers were defined as positive events during follow-up. Twenty-six of 68 (38%) NMIBC failed to BCG. Both positive post-BCG cytology and positive post-BCG FISH were significantly associated with failure of BCG (hazard ratio (HR)= 5.1 and HR= 5.6, respectively; p < 0.001 each) when compared to those with negative results. In the subgroup of nondefinitive cytology (all except those with unequivocally positive cytology), FISH was superior to cytology as a marker of relapse (HR= 6.2 and 1.4, respectively). Cytology and FISH in post-BCG bladder washings are highly interrelated and a positive result predicts failure to BCG therapy in patients with NMIBC equally well. FISH is most useful in the diagnostically less certain cytology categories but does not provide additional information in clearly malignant cytology.


Assuntos
Adjuvantes Imunológicos/uso terapêutico , Vacina BCG/uso terapêutico , Carcinoma Papilar/diagnóstico , Hibridização in Situ Fluorescente/estatística & dados numéricos , Neoplasias da Bexiga Urinária/diagnóstico , Administração Intravesical , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma in Situ/diagnóstico , Carcinoma in Situ/tratamento farmacológico , Carcinoma in Situ/genética , Carcinoma Papilar/tratamento farmacológico , Carcinoma Papilar/genética , Aberrações Cromossômicas , Citodiagnóstico , DNA de Neoplasias/análise , Feminino , Seguimentos , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Recidiva Local de Neoplasia/diagnóstico , Recidiva Local de Neoplasia/genética , Prognóstico , Estudos Prospectivos , Neoplasias da Bexiga Urinária/tratamento farmacológico , Neoplasias da Bexiga Urinária/genética
8.
Wien Klin Wochenschr ; 120(11-12): 325-34, 2008.
Artigo em Alemão | MEDLINE | ID: mdl-18709519

RESUMO

Acute ureteral colic presents with a complex of acute and characteristic flank pain that usually indicates the presence of a stone in the urinary tract. Diagnosis and management of renal colic have undergone considerable evolution and advancement in recent years. The application of noncontrast helical computed tomography (CT) in patients with suspected ureteral colic is one major advance in the primary diagnostic process. The superior sensitivity and specificity of helical CT allow ureterolithiasis to be diagnosed without the potential side effects of contrast media. Initial management is based on three key concepts: (A) rational and fast diagnostic process (B) effective pain control (C) and understanding of the impact of stone location and size on the natural course of the disease and definitive urologic management. These concepts are discussed in this review with reference to contemporary literature.


Assuntos
Cólica/diagnóstico por imagem , Tomografia Computadorizada Espiral , Doenças Ureterais/diagnóstico por imagem , Urografia , Doença Aguda , Analgésicos/efeitos adversos , Analgésicos/uso terapêutico , Anti-Inflamatórios não Esteroides/efeitos adversos , Anti-Inflamatórios não Esteroides/uso terapêutico , Cólica/terapia , Terapia Combinada , Humanos , Laparotomia , Litotripsia , Nefrostomia Percutânea , Sensibilidade e Especificidade , Cálculos Ureterais/diagnóstico por imagem , Doenças Ureterais/terapia , Ureteroscopia
9.
Urol Int ; 79(2): 137-41, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17851283

RESUMO

INTRODUCTION: Nephrectomy for autosomal dominant polycystic kidney disease (ADPKD) has been reported to have significant morbidity and mortality. Because of the large kidney size, laparoscopic nephrectomy is technically demanding and there have been only few reports on this subject. We describe our retroperitoneoscopic technique and review the literature. METHODS: Retroperitoneoscopic nephrectomy was performed in 2 patients. A four-port retroperitoneal access was used, after hilar control the kidney was freed and extracted. RESULTS: The mean operative time was 155 min, the mean intraoperative blood loss was 125 ml. There were no intraoperative complications. A postoperative retroperitoneal hematoma in 1 of the patients was managed conservatively with transfusion. CONCLUSION: Retroperitoneoscopic nephrectomy for ADPKD is feasible. The main advantages of this technique compared to transperitoneal laparoscopy are the quick and easy access to the hilar vessels even in large polycystic kidneys and the strict extraperitoneal route.


Assuntos
Nefrectomia/métodos , Rim Policístico Autossômico Dominante/cirurgia , Adulto , Feminino , Humanos , Laparoscopia , Masculino , Pessoa de Meia-Idade , Espaço Retroperitoneal
10.
PLoS One ; 12(8): e0182752, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28796813

RESUMO

Dysregulated human eccrine sweat glands can negatively impact the quality-of-life of people suffering from disorders like hyperhidrosis. Inability of sweating can even result in serious health effects in humans affected by anhidrosis. The underlying mechanisms must be elucidated and a reliable in vitro test system for drug screening must be developed. Here we describe a novel organotypic three-dimensional (3D) sweat gland model made of primary human eccrine sweat gland cells. Initial experiments revealed that eccrine sweat gland cells in a two-dimensional (2D) culture lose typical physiological markers. To resemble the in vivo situation as close as possible, we applied the hanging drop cultivation technology regaining most of the markers when cultured in its natural spherical environment. To compare the organotypic 3D sweat gland model versus human sweat glands in vivo, we compared markers relevant for the eccrine sweat gland using transcriptomic and proteomic analysis. Comparing the marker profile, a high in vitro-in vivo correlation was shown. Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), muscarinic acetylcholine receptor M3 (CHRM3), Na+-K+-Cl- cotransporter 1 (NKCC1), calcium-activated chloride channel anoctamin-1 (ANO1/TMEM16A), and aquaporin-5 (AQP5) are found at significant expression levels in the 3D model. Moreover, cholinergic stimulation with acetylcholine or pilocarpine leads to calcium influx monitored in a calcium flux assay. Cholinergic stimulation cannot be achieved with the sweat gland cell line NCL-SG3 used as a sweat gland model system. Our results show clear benefits of the organotypic 3D sweat gland model versus 2D cultures in terms of the expression of essential eccrine sweat gland key regulators and in the physiological response to stimulation. Taken together, this novel organotypic 3D sweat gland model shows a good in vitro-in vivo correlation and is an appropriate alternative for screening of potential bioactives regulating the sweat mechanism.


Assuntos
Glândulas Sudoríparas/citologia , Acetilcolina/farmacologia , Aquaporina 5/genética , Aquaporina 5/metabolismo , Biomarcadores/metabolismo , Sinalização do Cálcio , Técnicas de Cultura de Células , Polaridade Celular , Sobrevivência Celular , Células Cultivadas , Agonistas Colinérgicos/farmacologia , Humanos , Modelos Biológicos , Esferoides Celulares/citologia , Esferoides Celulares/fisiologia , Glândulas Sudoríparas/metabolismo , Transcriptoma
11.
J Cosmet Sci ; 57(1): 1-10, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16676119

RESUMO

Epidermal barrier function to water loss is maintained by lipid membrane domains located in the interstices of the stratum corneum. Exposure of the epidermis to a dry environment or UV irradiation stimulates barrier lipid synthesis and accumulation of the organic osmolyte taurine in the outermost granular keratinocyte layer. In this work we studied a possible relationship between these two different epidermal responses to environmental challenges. As a model system we selected anionic surfactant-induced barrier perturbation. Incubation of reconstructed epidermis with taurine inhibited cytotoxic and proinflammatory effects induced by sodium dodecyl sulfate including (i) a decrease in interleukin-1 alpha and prostaglandin E2 release, (ii) stabilization of keratinocyte membrane integrity, and (iii) improvement of keratinocyte viability. Repeated exposure of human skin to sodium dodecyl sulfate induced an increase in transepidermal water loss, inflammation, and hyperplasia. Topical application of taurine significantly decreased transepidermal water loss after repeated exposure to sodium dodecyl sulfate. Moreover, taurine significantly stimulated the synthesis of all three classes of barrier lipids (ceramides, cholesterol, and fatty acids) in reconstructed epidermis. In conclusion, our data suggest a role for taurine in preventing surfactant-induced dry and scaly skin by modulating the proinflammatory response and stimulating epidermal lipid synthesis.


Assuntos
Epiderme/efeitos dos fármacos , Ictiose/prevenção & controle , Dodecilsulfato de Sódio/farmacologia , Taurina/farmacologia , Perda Insensível de Água/efeitos dos fármacos , Administração Tópica , Dinoprostona/metabolismo , Epiderme/metabolismo , Humanos , Ictiose/induzido quimicamente , Ictiose/metabolismo , Interleucina-1/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Fenômenos Fisiológicos da Pele/efeitos dos fármacos , Taurina/administração & dosagem
12.
Oncogene ; 21(16): 2476-83, 2002 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-11971182

RESUMO

The chromosomal region 12q13-q15 is recurrently amplified in bladder cancer. Putative target genes located in this region include MDM2, CDK4, and GLI. To evaluate the involvement of these genes in bladder cancer, we screened a tissue microarray (TMA) containing 2317 samples by fluorescence in situ hybridization (FISH). Amplification was found for MDM2 in 5.1%, for CDK4 in 1.1%, and for GLI in 0.4% of interpretable tumors. Among tumors having amplification of at least one of these 12q13-q15 genes, 76.6% had amplification of MDM2 alone and 6.4% had amplification of CDK4 alone. Coamplifications were seen of MDM2 and CDK4 in 10.6%, and of CDK4 and GLI in 6.4%. Neither coamplifications of all three genes nor isolated GLI amplifications were found. These data suggest a prominent role of MDM2 as a 12q13-q15 amplification target in bladder cancer. However, independent CDK4 amplifications do also occur suggesting either two non-overlapping amplification sites or else a minimal overlapping region between MDM2 and CDK4 perhaps containing another yet unknown oncogene. The frequency of amplification increased significantly from stage pTa to pT1-4 (P<0.04) and from low to high grade (P<0.005). These data are consistent with a high level of genetic instability in invasively growing and high-grade bladder tumors.


Assuntos
Quinases Ciclina-Dependentes/genética , Amplificação de Genes , Proteínas Nucleares , Proteínas Oncogênicas/genética , Proteínas Proto-Oncogênicas/genética , Fatores de Transcrição/genética , Neoplasias da Bexiga Urinária/genética , Cromossomos Humanos Par 12 , Quinase 4 Dependente de Ciclina , Quinases Ciclina-Dependentes/metabolismo , Humanos , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas Oncogênicas/metabolismo , Prognóstico , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-mdm2 , RNA Neoplásico/biossíntese , Análise de Sobrevida , Transativadores , Fatores de Transcrição/metabolismo , Neoplasias da Bexiga Urinária/metabolismo , Neoplasias da Bexiga Urinária/mortalidade , Proteína GLI1 em Dedos de Zinco
13.
J Orthop Trauma ; 18(9): 611-6, 2004 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-15448450

RESUMO

OBJECTIVE: To test the hypothesis that oblique screws at the ends of a plate provide increased strength of fixation as compared to standard screw insertion. DESIGN: Biomechanical laboratory study in synthetic bone test medium. METHODS: Narrow 4.5-mm stainless steel low-contoured dynamic compression plates were anchored with cortical screws to blocks of polyurethane foam. The fixation strength in cantilever bending (gap closing mode) and torsion was quantified using a material testing system. Different constructs were tested to investigate the effect of the screw orientation at the end of the plate (straight versus oblique at 30 degrees), the plate, and bridging length as well as the number of screws. RESULTS: An oblique screw at the plate end produced an increased strength of fixation in all tests; however, the difference was more significant in shorter plates and in constructs with no screw omission adjacent to the fracture site. Both longer plates and increased bridging length produced a significantly stronger construct able to withstand higher compression loads. Under torsional loading, the fixation strength was mainly dependent on the number of screws. CONCLUSIONS: The current data suggest that when using a conventional plating technique, plate length is the most important factor in withstanding forces in cantilever bending. With regard to resisting torsional load, the number of screws is the most important factor. Furthermore, oblique screws at the ends of a plate increase fixation strength.


Assuntos
Fraturas do Fêmur/cirurgia , Fraturas Cominutivas/cirurgia , Fenômenos Biomecânicos , Placas Ósseas , Parafusos Ósseos , Humanos , Anormalidade Torcional
14.
Biol Rev Camb Philos Soc ; 88(1): 1-14, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22616845

RESUMO

Insects exchange respiratory gases primarily using tracheal systems that are filled with gas. However, in different developmental and environmental circumstances, liquid can occupy the tracheal system, which can significantly impair its respiratory function. Insects therefore use a suite of mechanisms for tracheal filling, which is the process of replacing tracheal liquids with gas. We review these mechanisms for liquid removal and gas filling. By integrating recent molecular work with older physiological literature, we show that liquid removal likely involves active ion transport in the whole tracheal system. Gas filling reveals fascinating interactions between geometry, surface chemistry of the tracheal walls, the tracheal liquid, and dissolved gases. The temporal proximity to moulting allows for potentially complex interdependencies between gas filling, moult-associated hormone signaling, and cuticle sclerotization. We propose a mechanistic model for tracheal filling. However, because the composition of the liquid is unknown, it remains hypothetical.


Assuntos
Insetos/fisiologia , Troca Gasosa Pulmonar/fisiologia , Animais , Fenômenos Fisiológicos Respiratórios
15.
J Insect Physiol ; 56(5): 492-501, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-19524587

RESUMO

After decades of intensive research, the actual mechanism behind discontinuous gas exchange in insects has not been fully understood. One open question concerns the actual way (closed, flutter, and open) of how spiracles respond to tracheal gas concentrations. As the results of a classic paper [Burkett, B.N., Schneiderman, H.A., 1974. Roles of oxygen and carbon dioxide in the control of spiracular function in cecropia pupae. Biological Bulletin 147, 274-293] allow ambiguous interpretation, we thus reexamined the behavior of the spiracles in response to fixed, controlled endotracheal gas concentrations. The tracheal system of diapausing pupae of Attacus atlas (Saturniidae, Lepidoptera) was flushed with gas mixtures varying in P(O(2)) and P(CO(2)) while the behavior of the spiracles was monitored using changes in the pressure signal. This novel pressure based technique proved to be superior to classic visual observation of single spiracles. A two-dimensional map of the spiracle behavior in response to endotracheal P(O(2)) and P(CO(2)) was established. Typically, it contained two distinct regions only, corresponding to "closed" and "open" spiracles. A separate "flutter" region was missing. Because fluttering is commonly observed in moth pupae, we suggest that the intermittent spiracle opening during a flutter phase is an effect of non-steady-state conditions within the tracheal system. For low P(CO(2)) the minimum P(O(2)) resulting in open spiracles was linearly dependent upon P(CO(2)). Above a threshold of 1-1.5 kPa CO(2) the spiracles were open irrespective of P(O(2)). We propose a hypothetical spiracular control model, which is simple and explains the time course of endotracheal partial pressures during all phases of discontinuous gas exchange.


Assuntos
Estruturas Animais/fisiologia , Dióxido de Carbono/metabolismo , Mariposas/fisiologia , Oxigênio/metabolismo , Animais , Pupa/fisiologia
16.
J Insect Physiol ; 56(5): 551-8, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-19481765

RESUMO

Many flightless beetles like the large apterous dung beetle Circellium bacchus, possess a subelytral cavity (SEC) providing an extra air space below the elytra which connects to the tracheal system (TS) via metathoracic and abdominal spiracles. By measuring subelytral and intratracheal pressure as well as body movements and gas exchange simultaneously in a flow-through setup, we investigated the contribution of convection on Circellium respiratory gas exchange. No constriction phase was observed. TS and SEC pressures were always around atmospheric values. During interburst phase open abdominal spiracles and a leaky SEC led to small CO(2)-peaks on a continuous CO(2) baseline, driven by intermittent positive tracheal pressure peaks in anti-phase with small negative subelytral pressure peaks caused by dorso-ventral tergite action. Spiracle opening was accompanied by two types of body movements. Higher frequency telescoping body movements at the beginning of opening resulted in high amplitude SEC and TS pressure peaks. High frequency tergite movements caused subelytral pressure peaks and led to a saw tooth like CO(2) release pattern in a burst. We propose that during the burst open mesothoracic spiracles increase the compliance of the subelytral cavity allowing big volumes of tracheal air being pulled out by convection.


Assuntos
Estruturas Animais/fisiologia , Besouros/fisiologia , Fenômenos Fisiológicos Respiratórios , Animais , Dióxido de Carbono/metabolismo , Atividade Motora/fisiologia , Pressão
17.
Respir Physiol Neurobiol ; 173 Suppl: S65-73, 2010 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-20347054

RESUMO

While it has long been known that in small animals, such as insects, sufficient gas transport could be provided by diffusion, it is now recognized that animals generate and control convective flows to improve oxygen delivery across a range of body sizes and taxa. However, size-based methodological limitations have constrained our understanding of the mechanisms that underlie the production of these convective flows. Recently, new techniques have enabled the elucidation of the anatomical structures and physiological processes that contribute to creating and maintaining bulk flow in small animals. In particular, synchrotron X-ray imaging provides unprecedented spatial and temporal resolution of internal functional morphology and is changing the way we understand gas exchange in insects. This symposium highlights recent efforts towards understanding the relationship between form, function, and control in the insect respiratory system.


Assuntos
Convecção , Insetos/fisiologia , Insetos/ultraestrutura , Fenômenos Fisiológicos Respiratórios , Sistema Respiratório/ultraestrutura , Animais , Difusão , Oxigênio/metabolismo , Oxigênio/fisiologia , Síncrotrons , Raios X
19.
Exp Dermatol ; 16(11): 936-45, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17927577

RESUMO

The trimethylated amino acid l-carnitine plays a key role in the intramitochondrial transport of fatty acids for beta-oxidation and thus serves important functions in energy metabolism. Here, we have tested the hypothesis that l-carnitine, a frequently employed dietary supplement, may also stimulate hair growth by increasing energy supply to the massively proliferating and energy-consuming anagen hair matrix. Hair follicles (HFs) in the anagen VI stage of the hair cycle were cultured in the presence of 0.5-50 microm of l-carnitine-l-tartrate (CT) for 9 days. At day 9, HFs treated with 5 microm or 0.5 microm of CT showed a moderate, but significant stimulation of hair shaft elongation compared with vehicle-treated controls (P < 0.05). Also, CT prolonged the duration of anagen VI, down regulated apoptosis (as measured by TUNEL assay) and up regulated proliferation (as measured by Ki67 immunohistology) of hair matrix keratinocytes (P < 0.5). By immunohistology, intrafollicular immunoreactivity for TGFbeta2, a key catagen-promoting growth factor, in the dermal papilla and TGF-beta II receptor protein in the outer root sheath and dermal papilla was down regulated. As shown by caspase activity assay, caspase 3 and 7, which are known to initiate apoptosis, are down regulated at day 2 and day 4 after treatment of HFs with CT compared with vehicle-treated control indicating that CT has an immediate protective effect on HFs to undergo programmed cell death. Our findings suggest that l-carnitine stimulates human scalp hair growth by up regulation of proliferation and down regulation of apoptosis in follicular keratinocytes in vitro. They further encourage one to explore topical and nutraceutical administration of l-carnitine as a well-tolerated, relatively safe adjuvant treatment in the management of androgenetic alopecia and other forms of hair loss.


Assuntos
Carnitina/farmacologia , Folículo Piloso/efeitos dos fármacos , Folículo Piloso/crescimento & desenvolvimento , Adulto , Apoptose/efeitos dos fármacos , Caspase 3/metabolismo , Caspase 7/metabolismo , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Regulação para Baixo/efeitos dos fármacos , Folículo Piloso/metabolismo , Humanos , Queratinócitos/citologia , Queratinócitos/efeitos dos fármacos , Queratinócitos/metabolismo , Masculino , Pessoa de Meia-Idade , Proteínas Serina-Treonina Quinases/metabolismo , Receptor do Fator de Crescimento Transformador beta Tipo II , Receptores de Fatores de Crescimento Transformadores beta/metabolismo , Tartaratos/farmacologia , Fator de Crescimento Transformador beta2/metabolismo
20.
Eur Urol ; 51(4): 1031-8; discussion 1038-41, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16945475

RESUMO

OBJECTIVES: Ongoing oral anticoagulation (OA) contraindicates transurethral electroresection of the prostate. We evaluated the safety and effectiveness of photoselective vaporization of the prostate (PVP) in patients on ongoing OA with coumarin derivatives, aspirin, or clopidogrel, complaining of symptomatic benign prostatic hyperplasia (BPH). METHODS: We evaluated perioperative parameters, functional outcome, and adverse events up to 24 mo postoperatively of patients on OA, and compared results with 92 men at normal risk without anticoagulant therapy undergoing PVP for the same indication (control). RESULTS: Within 40 mo, 116 men on OA were included, with 31% (n=36) receiving coumarin derivatives; 61% (n=71), aspirin; and 8% (n=9), clopidogrel. Mean prostate volume (62+/-34ml vs. 57+/-25ml; p=0.289) and mean operation time (67+/-28min vs 63+/-29min; p=0.313) were comparable with control. We observed no bleeding complications necessitating blood transfusions. Average postoperative decrease of haemoglobin was 8.6% for patients on OA versus 8.8% for control. At 3, 6, 12, and 24 mo postoperatively, improvement of the International Prostate Symptom Score ranged from 60-70%; postvoid residual volume, 80-88%; and average maximum urinary flow rate, 116-140%, respectively. Postoperative complications were low and comparable with control. CONCLUSIONS: PVP is characterized by excellent haemostatic properties and very low intraoperative complication rate even in patients on OA. On the basis of our perioperative results, we recommend PVP as first-line procedure for patients with symptomatic BPH at high risk of bleeding.


Assuntos
Anticoagulantes/administração & dosagem , Hiperplasia Prostática/cirurgia , Ressecção Transuretral da Próstata , Administração Oral , Idoso , Idoso de 80 Anos ou mais , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Hiperplasia Prostática/complicações , Fatores de Risco , Segurança , Ressecção Transuretral da Próstata/efeitos adversos
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