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排序方式: 共有8308条查询结果,搜索用时 15 毫秒
51.
52.
Multifunctional microcapsules for pancreatic islet cell entrapment: design,preparation and in vitro characterization 总被引:2,自引:0,他引:2
Luca G Basta G Calafiore R Rossi C Giovagnoli S Esposito E Nastruzzi C 《Biomaterials》2003,24(18):3101-3114
Great advances in cell transplantation have been made, including the recent, remarkable success in pancreatic islet transplantation for the treatment of type 1 diabetes mellitus. Unfortunately, the transplanted cells are very susceptible to oxidative stress that cause severe damage to either allo- or xenogeneic islets upon graft in diabetic patients. Consequently, the transplanted islet functional life span is significantly shortened. The aim of this study was to examine the possible effects of antioxidants on in vitro cultured adult rat islets, and to evaluate the effects of a prolonged-release formulation, in form of cellulose acetate (CA) microspheres, on Vitamin D(3) activity. Isolated rat islets, both free and entrapped in microspheres were treated with Vitamin D(3). The effects of the vitamin were studied at 3, 6 and 9 days of in vitro cell culture. According to insulin secretory patterns, treatment with Vitamin D(3) of both free and CA entrapped microspheres, increased the insulin output as compared to untreated controls. Such positive effects were confirmed under islet static incubation with glucose at day 6. These results suggest that pancreatic islets can be advantageously treated with anti-oxidising vitamins before implantation, and speculatively, with the help of special delivery systems, throughout the islet cell life span, in the post-transplant time period. 相似文献
53.
Lauretta D Polosa R 《The Journal of allergy and clinical immunology》2005,115(5):1097-8; author reply 1098-9
54.
STUDY OBJECTIVES: Based on studies of the impact of esophageal pressure on cardiovascular variables during sleep, this signal can be used to refine the severity level in the clinical diagnosis of obstructive sleep apnea syndrome. We hypothesized that relative changes in diaphragmatic electromyogram (EMG) can reflect short-term changes in esophageal pressure durng obstructive apneas and hypopneas. DESIGN: Diaphragmatic EMG was sampled at 0.25 kHz; diaphragmatic EMG waveform was band-pass filtered and digitally converted; the electrocardiogram artifact was eliminated; using a gating procedure, the waveform was fast-Fourier transformed and digitally rectified; and a moving average of 200 milliseconds was calculated. For each inspiratory effort during apnea or hypopnea, we calculated maximum diaphragmatic EMG and esophageal pressure. Data were normalized calculating the percentage difference between the first obstructed and each subsequent inspiratory effort during the respiratory event. SETTING: Sleep disorders laboratory. PATIENTS: 9 patients with moderate obstructive sleep apnea syndrome presenting with apneas and hypopneas during sleep. INTERVENTION: None. MEASUREMENTS AND RESULTS: 861 respiratory events were scored, and the evolution between esophageal pressure and diaphragmatic EMG were compared. Normalized data showed a good correlation between the 2 measures during apneas and hypopneas. There was a significant difference between the percentage increase in esophageal pressure and diaphragmatic EMG for apneas and hypopneas (esophageal pressure, apnea: 118.1% +/- 118.5%, hypopnea: 76.1% +/- 74.3%, P = .000; diaphragmatic EMG, 123.5% +/- 131.7%, hypopnea: 73.3% +/- 74.2%, P = .000). No significant differences for apnea or hypopnea were noted between the 2 measures under investigation. CONCLUSION: Diaphragmatic EMG may be clinically useful to describe relative changes in respiratory effort under conditions of apnea and hypopnea during sleep and to reliably dissociate central from obstructive events where esophageal pressure monitoring is not readily available. 相似文献
55.
Prosperini G Spicuzza L Polosa R 《The Journal of allergy and clinical immunology》2003,111(6):1416; author reply 1416-1416; author reply 1417
56.
Riccardo Castiglia Silvia Garagna Valeria Merico Nicholas Oguge Marco Corti 《Chromosome research》2006,14(5):587-594
We present the results of a cytogenetic study on Mus (Nannomys) minutoides from Kenya by means of C- and G- banding and in-situ fluorescence hybridization (FISH) to localize the telomeric sequences. The karyotype is characterized by the occurrence of
several Rb chromosomes Rb(1.X), Rb(1.Y). Rb(2.17), Rb(3.13), Rb(4.10), Rb(5.11), Rb(6.7), Rb(8.12), not previously described
for this species. This finding suggests a high level of chromosomal diversification, which means it is possible to consider
this cytotype as a new, well-differentiated, chromosomal lineage within the subgenus. The C-banding of the metaphases illustrated
conspicuous blocks of centromeric heterochromatin at the paracentromeric regions of all telocentric chromosomes. Centromeric
heterochromatin is not visible on all biarmed chromosomes. Following hybridization with telomeric probes, bright interstitial
telomeric sequence (ITS) fluorescence signals are evident at the pericentromeric area of all Rb chromosomes, with the exception
of Rb(2.17). Considering the localization of the C-positive heterochromatin and of the telomeric sequences, the events leading
to the Kenyan cytotype from an all-telocentric condition probably included two steps: first, fusion without loss of heterochromatin
and pericentromeric telomeric sequences; second, the reduction of the C-positive satellite DNA followed by the amplification
of telomeric sequences in the C-negative paracentromeric region of Rb chromosomes. The presence of a single Rb(2.17) without
ITS indicates possible variations of this mechanism. 相似文献
57.
Activation of group I mGluRs elicits different responses in murine CA1 and CA3 pyramidal cells 总被引:3,自引:1,他引:3
Shih-Chieh Chuang Wangfa Zhao Steven R. Young François Conquet Riccardo Bianchi Robert K. S. Wong 《The Journal of physiology》2002,541(1):113-121
The group I metabotropic glutamate receptor agonist DHPG has been shown to produce two major effects on CA3 pyramidal cells at rest: a reduction in the background conductance and an activation of a voltage-gated inward current ( I mGluR(V) ). Both effects contribute to depolarising CA3 pyramidal cells and the latter has been implicated in eliciting prolonged epileptiform population bursts. We observed that DHPG-induced depolarisation was smaller in CA1 pyramidal cells than in CA3 cells. Voltage clamp studies revealed that while DHPG elicited I mGluR(V) in CA3 pyramidal cells, such a response was absent in CA1 pyramidal cells. Both mGluR1 and mGluR5 have been localised in CA3 pyramidal cells, whereas only mGluR5 has been detected in CA1 pyramidal cells. Using mGluR1 knockout mice, we evaluated whether the absence of an I mGluR(V) response can be correlated with the absence of mGluR1. In these experiments, DHPG failed to elicit I mGluR(V) in CA3 pyramidal cells. This suggests that the smaller depolarising effects of DHPG on wild-type CA1 pyramidal cells is caused, at least in part, by the absence of I mGluR(V) in these cells and that the difference in the responses of CA1 and CA3 cells may be attributable to the lack of mGluR1 in CA1 pyramidal cells. 相似文献
58.
59.
60.
Magni P Sparacino G Bellazzi R Toffolo GM Cobelli C 《Annals of biomedical engineering》2004,32(7):1027-1037
The identification of the insulin minimal model (MM) for the estimation of insulin secretion rate (ISR) and physiological indexes (e.g. beta-cell sensitivity) requires the knowledge of C-peptide (CP) kinetics. The four parameters of the two-compartment model of CP kinetics in a given individual can be derived either from an additional bolus experiment or, more frequently, from a population model. However, in both situations, the CP kinetics is uncertain and, in MM identification, it should be treated as such. This paper shows how to handle CP kinetics uncertainty by using a Bayesian methodology. In seven subjects, MM indexes and ISR were estimated together with their confidence intervals, using either the bolus data or the population model to assess CP kinetics. The two main results that arise from the application of the new methodology are: (i) the use of the population model in place of the bolus data to determine CP kinetics does not affect, on average, the point estimates of ISR profile and MM parameters but only the confidence intervals which becomes wider (less than 50%); (ii) in both the bolus and population situation neglecting the uncertainty of CP kinetics, as done in MM literature so far, introduces no bias, on average, on point estimates of MM indexes but only an underestimation of confidence intervals. 相似文献