Radiofrequency ablation in the liver close to the bile ducts: can intraductal cooling offer protection?

Background One complication of radiofrequency ablation (RFA) of the liver is biliary duct damage. Intraductal cooling (IDC) has been proposed as a means of protection.Methods In the first experiment, designed to evaluate the influence of IDC on the RFA procedure per se and on lesion formation, lesions were created in vivo in pig liver with and without IDC. The RFA needle was placed with a 1.5-cm safety margin from the bile ducts. In the second experiment, designed to evaluate the potential protective effects of IDC, lesions were created close to a bile duct with and without IDC.Results With the safety margin, the RFA parameters and lesion size were not negatively affected by IDC. Microscopic examination revealed that IDC had a protective effect in most of the lesions created close to a bile duct.Conclusions The IDC procedure was feasible and had no negative effect on the RFA procedure or the lesions. However, the protective effect of IDC was not statistically significant (p = 0.12).     

Influence of temperature on neuromuscular transmission in myasthenia gravis

Summary The effect of local cooling was studied in 28 patients with myastenia gravis. We stimulated the ulnar nerve with single stimuli and trains at 3/s for 2s and at 50/s for 1.5s. The compound muscle action potential (MAP), the muscle twitch and the isometric tetanic force of the adductor pollicis were registered. 1. At 3/s stimulation the pathological decrement of the MAP decreased after slight cooling. 2. The amplitude of the single MAP was higher at lower temperature when compared to normal temperature. The same increase is however to be found in healthy subjects. 3. After slight cooling, the maximum tetanic force was higher. However, the decrement of the force was higher also, therefore ruling out a practicable application of cooling for the patient. 4. After severe cooling (18–22°C) the tetanic force was much lower and in many cases a complete failure of the neuromuscular transmission occured.

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Zusammenfassung Der Einfluß lokaler Kühlung wurde an 28 Patienten mit Myasthenia gravis untersucht. Wir reizten den N. ulnaris mit einzelnen Impulsen und mit Serien von 3/s für 2s und von 50/s für 1.5s. Das Summenaktionspotential (MAP), die Muskelzuckung und die isometrische tetanische Kraft des Adduktor pollicis wurden registriert. 1. Bei Reizung mit 3/s war das pathologische Dekrement des MAP nach leichter Kühlung geringer. 2. Die Amplitude des MAP war größer. Diese Amplitudenzunahme tritt jedoch auch bei Gesunden nach Kühlung auf. 3. Nach leichter Kühlung war die maximale tetanische Kraft größer. Jedoch nahm die Kraft während der Reizung nach dem Maximum wieder schnell ab. Der praktische Nutzen einer Kühlung ist deshalb für den Patienten gering. 4. Nach starker Kühlung (18–22°C) war die maximale tetanische Kraft sehr niedrig. In vielen Fällen kam es zu einem vollständigen Versagen der neuromuskulären Impulsübertragung.

     

Hippocampal formation is required for geometric navigation in pigeons

The geometric properties of bounded space have attracted considerable attention as a source of spatial information that can guide goal navigation. Although the use of geometric information to navigate has been observed in every species studied to date, the neural mechanisms that support the representation of geometric information are still debated. With the purpose of investigating this topic, we trained pigeons with lesion to the hippocampal formation to search for food in a rectangular-shaped arena containing one wall of a different color that served as the only distinctive environmental feature. Although lesioned pigeons learned the task even faster than control animals, probe trials showed that they were insensitive to geometric information. Control animals could encode and use both geometric and feature information to locate the goal. By contrast, lesioned pigeons relied exclusively on the feature information provided by the wall of a different color. The results indicate that the avian hippocampal formation is critical for learning the geometric properties of space in homing pigeons.     

Terminology associated with vitrification and other cryopreservation procedures for oocytes and embryos

Over the past 30 years many cryopreservation procedures have been applied to oocytes, embryos, sperm, ovarian and testicular tissue. Over this time many, often specialized, terms have been developed for all aspects of these procedures. This can make it difficult for readers who are not familiar with the terminology or protocols to compare and evaluate different procedures. This paper describes the main cryopreservation procedures, the terminology associated with them, and briefly explains the underlying physical, chemical and biological processes. The aim is to help readers understand and interpret other papers on slow cooling, rapid cooling, ultrarapid cooling and vitrification.     

Effect of cooling procedure on final denture base adaptation

Well-fitted dentures prevent hyperplasic lesions, provide chewing efficiency and promote patient's comfort. Several factors may affect final adaptation of dentures, as the type of the acrylic resin, the flask cooling procedure and the water uptake. This investigation evaluated the effect of water storage and two different cooling procedures [bench cooling (BC) for 2 h; running water (RW) at 20 degrees C for 45 min] on the final adaptation of denture bases. A heat-cured acrylic resin (CL, Clássico, Clássico Artigos Odontológicos) and two microwave-cured acrylic resins [Acron MC, (AC) GC Dent. Ind. Corp.; Onda Cryl (OC), Clássico Artigos Odontológicos] were used to make the bases. Adaptation was assessed by measuring the weight of an intervening layer of silicone impression material between the base and the master die. Data was submitted to ANOVA and Tukey's test (0.05). The following means were found: (BC) CL=0.72 +/- 0.03 a; AC=0.70 +/- 0.03 b; OC=0.76 +/- 0.04 c//(RW) CL= 1.00 +/- 0.11 a; AC=1.00 +/- 0.12 a; OC=0.95 +/- 0.10 a. Different labels join groups that are not statistically different (P > 0.05). Comparisons are made among groups submitted to the same cooling procedure (BC or RW). The conclusions are: interaction of type of material and cooling procedure had a statistically significant effect on the final adaptation of the denture bases (P < 0.05); water storage was not detected as a source of variance (P > 0.05) on the final adaptation.     

Thermal response of human skin epidermis to 595-nm laser irradiation at high incident dosages and long pulse durations in conjunction with cryogen spray cooling: an ex-vivo study

BACKGROUND AND OBJECTIVES: Improved laser treatment of cutaneous hypervascular lesions is expected by utilizing higher incident dosages, longer pulse durations and longer wavelengths than those currently used in clinical settings. However, simply increasing the incident dosage will also increase the risk of nonspecific thermal injury to the epidermis due to light absorption by melanin. In this study, we investigated the thermal response of human skin epidermis to 595-nm wavelength laser irradiation at high incident dosages (up to 20 J/cm(2)) and long pulse durations (up to 40 milliseconds) in conjunction with cryogen spray cooling (CSC) using ex-vivo human skin samples. STUDY DESIGN/MATERIALS AND METHODS: The Candela V-beam trade mark laser (595-nm wavelength) was used in the experiments. Ex-vivo human skin samples (Fitzpatrick types I-VI) were irradiated at the incident dosages D(0) = 4, 6, 10, 15, and 20 J/cm(2), laser pulse durations tau(laser) = 1.5, 10, and 40 milliseconds, without and with CSC (refrigerant-134A, spurt duration tau(CSC) = 100 milliseconds). Thermal injury to the epidermis was evaluated by histological observations. RESULTS: Under the same incident dosage, longer pulse durations led to reduced thermal injury to the epidermis. Without CSC, no demonstrable thermal injury to the epidermis was observed in skin types I-II irradiated at the incident dosage as high as 15 J/cm(2), and in skin types III-IV at 10 J/cm(2). When CSC was applied, no evidence of thermal injury to the epidermis was present in skin types I-II even when irradiated at the maximum available incident dosage of the laser system (20 J/cm(2)). In skin types III-IV, no demonstrable thermal injury to the epidermis was observed when using incident dosage as high as 15 J/cm(2) in conjunction with CSC. In skin type VI, thermal injury to the epidermis could not be avoided even at the setting D(0) = 4 J/cm(2), tau(laser) = 40 milliseconds in conjunction with CSC. CONCLUSIONS: For a given incident dosage, longer pulse durations help reduce thermal injury to the epidermis. When a 100-millisecond cryogen spurt is applied, thermal injury to the epidermis can be prevented in ex-vivo skin types I-IV when irradiated at higher incident dosages (15-20 J/cm(2)) than those currently used in clinical settings. Further studies on optimizing the CSC parameters in conjunction with the laser irradiation parameters are needed to protect skin types V-VI from thermal injury to the epidermis.     

Developmental study of dendritic bundles in layer 1 of the rat granular retrosplenial cortex with special reference to a cell adhesion molecule, OCAM

In the granular retrosplenial cortex (GRS) of adult rats, callosally projecting pyramidal neurons in layer 2 form dendritic bundles, 30-100 micro m wide, in layer 1. The distinctness of these bundles makes the GRS an attractive model system for investigating the developmental, microcircuitry, and basic organizational features related to dendritic modularity. In this report, we investigate the developmental time course of the dendritic bundles, visualized by immunohistochemistry for microtubule-associated protein 2 (MAP2) and glutamate receptor subunits 2/3 (GluR2/3). Bundles in layer 1 are apparent as early as postnatal day 5, first with GluR2/3 and then, from postnatal day 14, with MAP2. As a step toward understanding the mechanisms of dendritic aggregation, we further investigated the ontogeny of expression of the cell adhesion molecule OCAM. OCAM exhibits a patchy distribution in layer 1 from postnatal day 3 to adult, and the regions of weak OCAM immunoreactivity selectively correspond to the dendritic bundles (in both GluR2/3 and MAP2). The periodic geometry of OCAM-immunoreactive regions, the time course of their appearance and the distinct localization complementary to the bundles support the possibility that this molecule is one contributor to the establishment and maintenance of dendritic modules. The interdigitating relationship between regions of high OCAM immunoreactivity and the dendritic bundles in layer 1 suggests that OCAM may have a repellent influence on the formation of these bundles.     

人体解剖学模块课程的设计与实践

模块课程理论是近年来世界课程理论研究的重要内容。将人体解剖学课程划分为5个大模块,并对模块课程的性质、设计思路、目标和评价方法等作了探讨。人体解剖学模块课程是一种小型化、现代化课程模式,具有很强的灵活性和实践性,更能体现时代气息。     

Grafting an RGD motif onto an epidermal growth factor-like module: chemical synthesis and functional characterization of the chimeric molecule

Abstract: A novel protein was engineered by inserting the GRGDS motif of fibronectin within the 14-residue loop of the EGF-like module from human complement protease C1r. The resulting chimeric EGF-RGD module (52 residues, three disulfide bridges) was assembled by automated solid-phase synthesis using the t-Boc strategy. Using reduced/oxidized glutathione, the EGF-RGD module was folded as efficiently as the natural C1r-EGF module, resulting in formation of the appropriate disulfide bridge pattern as shown by mass spectrometry and N-terminal sequence analyses of thermolytic fragments. Circular dichroism and NMR measurements provided further indication that introduction of the GRGDS motif had no significant effect on the folding. Using Chinese Hamster Ovary (CHO) cells bearing the integrin receptors specific for fibronectin and vitronectin, EGF-RGD was shown to induce cell adhesion via the introduced GRGDS motif. Cell binding was inhibited specifically and efficiently by the synthetic peptide GRGDSP and by fibronectin, and to a much lesser extent by vitronectin, whereas the monoclonal antibody PB1 directed to the α5 subunit of α5β1 integrin had no effect. The ability of EGF-RGD to trigger significant cell spreading and intracellular signaling was also demonstrated using immunofluorescence and confocal microscopy.