An adaptive spatio-temporal Gaussian filter for processing cardiac optical mapping data.

Optical mapping is widely used as a tool to investigate cardiac electrophysiology in ex vivo preparations. Digital filtering of fluorescence-optical data is an important requirement for robust subsequent data analysis and still a challenge when processing data acquired from thin mammalian myocardium. Therefore, we propose and investigate the use of an adaptive spatio-temporal Gaussian filter for processing optical mapping signals from these kinds of tissue usually having low signal-to-noise ratio (SNR). We demonstrate how filtering parameters can be chosen automatically without additional user input. For systematic comparison of this filter with standard filtering methods from the literature, we generated synthetic signals representing optical recordings from atrial myocardium of a rat heart with varying SNR. Furthermore, all filter methods were applied to experimental data from an ex vivo setup. Our developed filter outperformed the other filter methods regarding local activation time detection at SNRs smaller than 3 dB which are typical noise ratios expected in these signals. At higher SNRs, the proposed filter performed slightly worse than the methods from literature. In conclusion, the proposed adaptive spatio-temporal Gaussian filter is an appropriate tool for investigating fluorescence-optical data with low SNR. The spatio-temporal filter parameters were automatically adapted in contrast to the other investigated filters.

Hallazgo frecuente de patologías infrecuentes de bazo / A common finding in uncommon splenic entity

El dolor abdominal es una de las causas mas frecuentes de consulta a los servicios de urgencias, por lo cual la evaluacion cuidadosa es fundamental para llegar a un diagnostico acertado, con el deseo de diferenciar oportunamente las patologias medicas de aquellas de manejo quirurgico. El bazo rara vez es causa de abdomen agudo. Se presentan aqui los casos clinicos de tres pacientes atendidos en el Servicio de Urgencias de la Clinica Rafael Uribe Uribe del Instituto de Seguros Sociales en Cali (Colombia), en cada uno de los cuales se diagnostico una enfermedad esplenica diferente, de rara ocurrencia, y que fueron tratados todos quirurgicamente con esplenectomia.

Prognostic significance of Ki-67 immunostaining in nonmetastatic renal cell carcinoma.

PURPOSE: Fresh tissue samples from nonmetastatic renal cell carcinoma (RCC) patients were analyzed by Ki-67 immunostaining to determine the prognostic significance of this tumor-biologic parameter. MATERIALS AND METHODS: In a prospective study, Ki-67 immunostaining was performed on frozen sections of histologically proven node-negative RCC from 58 patients operated on between 1986 and 1988 to examine the method's prognostic value and its association with other clinicopathologic parameters such as tumor stage (pT) and grade (G). RESULTS: The percentage of Ki-67-positive cells (ie, the proliferation rate [PR]) of all 58 RCC tumors ranged between 1% and 23%, while normal renal tissue exhibited PRs up to 2% only. In almost all cases, the highest PRs were observed in the peripheral zone of malignant tissue close to the normal renal tissue. PR did not correlate with pT, whereas a strongly significant correlation was observed between PR and G, as well as recurrence rate. Twenty-three of 58 patients (39.6%) developed tumor recurrence. Disease-free survival was strongly associated with PR. In a multivariate analysis, G and PR were independent prognostic markers. CONCLUSION: The tumor-specific PR obtained by Ki-67 labeling seems to be an independent marker to describe the proliferative activity and aggressiveness of individual tumors. This new tumor-biologic marker detects RCC patients at high risk for recurrent disease, especially in those cases with identical pT and G.

In vitro sensitivity testing of human renal cell carcinoma with cytostatic agents and interferon alpha-2a.

Samples of 38 human renal cell carcinomas (RCC) were subjected to routine histopathological examination but also to in vitro sensitivity testing with mitomycin C, vinblastine and interferon Alpha-2a at various concentrations corresponding to serum titers recommended to be effective in vivo, employing a monolayer assay. Extending earlier in vitro studies, both tumor cell kill rates (TCKR) and proliferation rates (PR) were assessed. Following in vitro preparation the tumor cell cultures were simultaneously exposed to the anticancer drugs listed above. The proliferation rates were determined immunocytochemically using the monoclonal antibody Ki-67. Nine (23.7%) of the tumors investigated revealed temporary and limited response with respect to either TCKR or PR. Improvement of this percentage could only be obtained by increasing drug concentration to titers with toxicity intolerable for in vivo administration. The in vivo data presented correspond to clinical temporary and limited remissions in patients with metastatic RCC ranging up to 25%.

[In vitro sensitivity testing of human kidney tumors to cytostatic drugs with a rapid in vitro test]. / In-vitro-Sensibilitätstestung von menschlichen Nierentumoren gegenüber Zytostatika mit einem In-vitro-Kurzzeittest.

We present a new modified in vitro culture assay for primary human renal cell carcinoma similar to the 'soft agar clonogenic assay'. However, the carrying out and expense of metrology are more simplified, allowing tumor-specific chemotherapeutic drug sensitivity testing under easier conditions. Twelve different samples of human renal carcinoma and one sample of a transitional cell carcinoma of the renal pelvis were tested for in vitro chemotherapy sensitivity using this modified colony-forming assay. The rate of tumor cells establishing in culture was 100%. Corresponding to clinical experience we observed a nearly complete resistance to the cytotoxic effects of standard chemotherapeutic agents at usual plasma concentrations in man. Only higher concentrated chemotherapeutic drugs showed in vitro therapeutic effects. The assay described here lasts about 7 days, which is beneficial from the clinical point of view. The modification of this in vitro chemotherapeutic drug treatment is unlimited for plasma concentration and duration of standard and experimental chemotherapeutic agents, drug combination and so on. So we have interesting scientific steps which could not have been undertaken under usual clinical-empirical conditions.