Adaptive-weighted cubic B-spline using lookup tables for fast and efficient axial resampling of 3D confocal microscopy images.

Confocal laser scanning microscopy has become a most powerful tool to visualize and analyze the dynamic behavior of cellular molecules. Photobleaching of fluorochromes is a major problem with confocal image acquisition that will lead to intensity attenuation. Photobleaching effect can be reduced by optimizing the collection efficiency of the confocal image by fast z-scanning. However, such images suffer from distortions, particularly in the z dimension, which causes disparities in the x, y, and z directions of the voxels with the original image stacks. As a result, reliable segmentation and feature extraction of these images may be difficult or even impossible. Image interpolation is especially needed for the correction of undersampling artifact in the axial plane of three-dimensional images generated by a confocal microscope to obtain cubic voxels. In this work, we present an adaptive cubic B-spline-based interpolation with the aid of lookup tables by deriving adaptive weights based on local gradients for the sampling nodes in the interpolation formulae. Thus, the proposed method enhances the axial resolution of confocal images by improving the accuracy of the interpolated value simultaneously with great reduction in computational cost. Numerical experimental results confirm the effectiveness of the proposed interpolation approach and demonstrate its superiority both in terms of accuracy and speed compared to other interpolation algorithms.

An automatic segmentation algorithm for 3D cell cluster splitting using volumetric confocal images.

With the rapid advance of three-dimensional (3D) confocal imaging technology, more and more 3D cellular images will be available. Segmentation of intact cells is a critical task in automated image analysis and quantification of cellular microscopic images. One of the major complications in the automatic segmentation of cellular images arises due to the fact that cells are often closely clustered. Several algorithms are proposed for segmenting cell clusters but most of them are 2D based. In other words, these algorithms are designed to segment 2D cell clusters from a single image. Given 2D segmentation methods developed, they can certainly be applied to each image slice with the 3D cellular volume to obtain the segmented cell clusters. Apparently, in such case, the 3D depth information with the volumetric images is not really used. Often, 3D reconstruction is conducted after the individualized segmentation to build the 3D cellular models from segmented 2D cellular contours. Such 2D native process is not appropriate as stacking of individually segmented 2D cells or nuclei do not necessarily form the correct and complete 3D cells or nuclei in 3D. This paper proposes a novel and efficient 3D cluster splitting algorithm based on concavity analysis and interslice spatial coherence. We have taken the advantage of using the 3D boundary points detected using higher order statistics as an input contour for performing the 3D cluster splitting algorithm. The idea is to separate the touching or overlapping cells or nuclei in a 3D native way. Experimental results show the efficiency of our algorithm for 3D microscopic cellular images.

False-positive screening results in the Finnish prostate cancer screening trial.

BACKGROUND: There is evidence that prostate cancer (PC) screening with prostate-specific antigen (PSA) serum test decreases PC mortality, but screening has adverse effects, such as a high false-positive (FP) rate. We investigated the proportion of FPs in a population-based randomised screening trial in Finland. METHODS: Finland is the largest centre in the European Randomized Study of Screening for Prostate Cancer. We have completed three screening rounds with a 4-year screening interval (mean follow-up time 9.2 years) using a PSA cutoff level of 4.0 ng ml(-1); in addition, men with PSA 3.0-3.9 and a positive auxiliary test were referred. An FP result was defined as a positive screening result without cancer in biopsy within 1 year from the screening test. RESULTS: The proportion of FP screening results varied from 3.3 to 12.1% per round. Of the screened men, 12.5% had at least one FP during three rounds. The risk of next-round PC following an FP result was 12.3-19.7 vs 1.4-3.7% following a screen-negative result (depending on the screening round), risk ratio 3.6-9.9. More than half of the men with one FP result had another one at a subsequent screen. Men with an FP result were 1.5 to 2.0 times more likely to not participate in subsequent rounds compared with men with a normal screening result (21.6-29.6 vs 14.0-16.7%). CONCLUSION: An FP result is a common adverse effect of PC screening and affects at least every eighth man screened repeatedly, even when using a relatively high cutoff level. False-positive men constitute a special group that receives unnecessary interventions but may harbour missed cancers. New strategies are needed for risk stratification in PC screening to minimise the proportion of FP men.

3D boundary extraction of confocal cellular images using higher order statistics.

In recent years, cell biologists have benefited greatly from using confocal microscopy to study intracellular organelles. For high-level image analysis, 3D boundary extraction of cell structure is a preliminary requisite in confocal cellular imaging. To detect the object boundaries, most investigators have used gradient/Laplacian operator as a principal tool. In this paper we propose a higher order statistics (HOS) based boundary extraction algorithm for confocal cellular image data set using kurtosis. After the initial pre-processing, kurtosis boundary map is estimated locally for the entire volume using a cubic sliding window and subsequently the noisy kurtosis value is removed by thresholding. Voxels having positive kurtosis value with zero-crossing on its surface are then identified as boundary voxels. Typically used in signal processing, kurtosis for 3D cellular image processing is a novel application of HOS. Its reliable and robust nature of computing makes it very suitable for volumetric cellular boundary extraction.

Prostate cancer incidence among finasteride and alpha-blocker users in the Finnish Prostate Cancer Screening Trial.

BACKGROUND: The Prostate Cancer Prevention Trial has shown a protective effect of finasteride on prostate cancer in low-risk men. It is uncertain whether similar results can be expected when finasteride is used to treat benign prostatic hyperplasia. METHODS: We performed an observational cohort study within the Finnish Prostate Cancer Screening Trial. Using a comprehensive prescription database on medication reimbursements during 1995-2004 of men using finasteride or alpha-blockers for benign prostatic hyperplasia, we evaluated prostate cancer incidence among 23 320 men screened during 1996-2004. RESULTS: Compared to medication non-users, overall prostate cancer incidence was not significantly affected in finasteride users (hazard ratio 0.87; 95% CI 0.63-1.19). Incidence of Gleason 2-6 tumours, however, was decreased among finasteride users (HR 0.59; 95% CI 0.38-0.91), whereas incidence of Gleason 7-10 tumours was unchanged (HR 1.33; 95% CI 0.77-2.30). The protective effect concerned mainly screen-detected tumours. Overall prostate cancer risk was not significantly reduced among alpha-blocker users relative to non-users, but decreased incidence of high-grade tumours was observed (0.55; 95% CI 0.31-0.96). CONCLUSIONS: The detection of low-grade, early-stage tumours is decreased among men who use finasteride for symptomatic BPH. The protective effect of finasteride can also be expected in men with benign prostatic hyperplasia.

Adaptive correction technique for 3D reconstruction of fluorescence microscopy images.

Recent advances in high-resolution imaging have provided valuable novel insights into structural relationships within cells and tissues both in vitro and in vivo. An analysis of this kind is regularly done by optical sectioning using either confocal or deconvolution microscopy. However, the reconstruction of 3D images suffers from light scattering and absorption with increasing depth by finite transparency of the used media. Photobleaching of fluorochromes has been especially troublesome and often the only remedy for loss of signal during optical sectioning is to reduce the number of sections. This causes disparities in the x-y and z dimensions of voxels, which lead to vertical distortion of the original stack of images and necessitates interpolation. Interpolation is necessary to fill up the gaps between consecutive sections in the original image stack to obtain cubic voxels. The present manuscript describes a novel method for adaptive compensation of attenuation of light intensity in stacks of fluorescence microscopy images that is based on a physical model of light attenuation. First, we use a fast interpolation technique to generate a cubic voxel-based volume stack with the aid of a contribution look up table. With the contribution look up table, multiple calculations are avoided, which substantially reduces the computational time without compromising the accuracy of the restoration procedure. Second, each section within the resulting volume is processed to rectify its intensity values that have been altered due to photobleaching and scattering and absorption. The method allows to define the last good section in the stack and the correction is then done automatically.

Specificity of serum prostate-specific antigen determination in the Finnish prostate cancer screening trial.

Specificity constitutes a component of validity for a screening test. The number of false-positive (FP) results has been regarded as one of major shortcomings in prostate cancer screening. We estimated the specificity of serum prostate-specific antigen (PSA) determination in prostate cancer screening using data from a randomised, controlled screening trial conducted in Finland with 32 000 men in the screening arm. We calculated the specificity as the proportion of men with negative findings (screen negatives, SN) relative to those with negative and FP results (SN/(SN+FP)). A SN finding was defined as either PSA

An automatic method for identifying appropriate gradient magnitude for 3D boundary detection of confocal image stacks.

Gradients play an important role in 2D image processing. Many edge detection algorithms are gradient-based. We are interested in 3D boundary detection which can be considered as an extension of 2D edge detection in 3D space. In this paper, an algorithm to automatically and quantitatively measure the suitability of gradient magnitudes in detection of 3D boundary points of confocal image stacks is presented. A Measurement Function is defined to evaluate the suitability of each gradient magnitude chosen to be the threshold for 3D boundary detection. The application of Gauss's Divergence Theorem provides a solution to calculate the Measurement Function numerically. The gradient magnitude at which the maximum of the Measurement Function is achieved can be utilized as the most appropriate threshold for gradient-based boundary detection and other operations like volume visualization.

Bladder management in persons with spinal cord lesion.

STUDY DESIGN: Cross-sectional clinical descriptive prevalence study. OBJECTIVE: To evaluate the methods of self-reported bladder management, the frequency of urinary tract infection (UTI) and subjective disturbance of bladder problems of all those individuals with traumatic spinal cord lesion (SCL) living in Helsinki area. SETTING: : Helsinki, Finland. METHODS: A total of 152 persons with SCL were found in the Helsinki area (546 000 inhabitants). A structured questionnaire was sent to all subjects and they were invited to a clinical visit. RESULTS: The final study-group consisted of 129 (85%) subjects. They were defined into seven specific subgroups of bladder management: 14 (11%) subjects in the normal voiding group, 15 (12%) in the controlled voiding group, 16 (12%) in the clean intermittent catheterization (CIC) group, 30 (23%) in the mixed group, 31 (24%) in the suprapubic tapping group, 16 (12%) in the compression or straining group and seven (5%) in the catheter or conduit group. The frequency of UTI was highest in the mixed group. The bladder management was a biggest bother to the subjects in the compression or straining group. CONCLUSIONS: This prevalence study assesses the self-reported bladder management methods in all the persons with traumatic SCL in the Helsinki area. The subjects who used CIC and other methods for bladder management had more problems than others. These subjects might manage better by using either CIC or suprapubic tapping as the only method for bladder emptying.

A randomized trial of choice of treatment in prostate cancer: the effect of intervention on the treatment chosen.

OBJECTIVE: To determine whether different approaches in the choice of treatment affect the treatment chosen by the patient for prostate cancer. PATIENTS AND METHODS: We conducted a randomized trial with 210 men who had a histologically confirmed diagnosis of prostate cancer in 1993-94 at four major hospitals in Finland. After obtaining informed consent the men were randomized either to an intervention arm, in which there was greater patient participation in the choice of treatment following a structured procedure, or a control arm in which the standard approach, i.e. a standardized treatment protocol, was used. The main outcome measure of the analysis was the primary treatment chosen for prostate cancer. RESULTS: In the enhanced participation arm patients not eligible for radical prostatectomy chose orchidectomy less frequently and favoured nonsurgical endocrine treatment than in the treatment protocol arm. Radical prostatectomy was the most commonly chosen treatment option in both arms among men with operable cancer. The way treatment options were presented affected the treatment chosen for prostate cancer. CONCLUSION: Patients with prostate cancer are willing and able to take an active role in making decisions. The preferences of patients with prostate cancer in the choice of treatment may differ from the priorities of the physicians.

The effect of photodynamic therapy on rat urinary bladder with orthotopic urothelial carcinoma.

OBJECTIVE: To assess the effect of whole-bladder photodynamic therapy (PDT) on a rat model with orthotopic superficial bladder cancer, as PDT is an alternative intravesical therapy for treating superficial bladder cancer, based on an interaction between a photosensitizer and light energy to induce oxygen radicals that destroy tissue by lipid peroxidation. MATERIALS AND METHODS: In all, 76 female Fischer F344 rats were inoculated intravesically with AY-27 tumour cells. After establishing superficial tumour, 24 rats were treated with PDT using aminolaevulinic acid (ALA)-induced protoporphyrin IX as a photosensitizer, and a continuous-wave argon pumped-dye laser (638 nm). At 4 h after intravenous (300 mg/kg) or intravesical (100 mg/mL) administration of ALA the bladders were intravesically exposed to a 40 J/cm(2) light dose; 12 rats received no ALA but were exposed to the same light dose. Before administering ALA, urine cytology samples were taken for analysis. At 3 or 21 days the treated rats were killed and morphological changes in the bladder walls analysed by light microscopy. Forty rats served as controls to examine the presence of tumour. RESULTS: The tumour established in 33 of 40 rats (83%) in the controls, but after PDT with intravesical ALA there was carcinoma in only in one of 12 (P < 0.001, Pearson's chi(2) test). After PDT with intravenous ALA there was carcinoma in five of 11 rats (P = 0.063, Pearson's chi2 test). In the control group of 12 rats receiving only light energy there was carcinoma in three (P = 0.001, Pearson's chi(2) test). Histologically, at 3 days after PDT there was only mild superficial damage in all six rats treated intravesically. Bladder wall destruction reached the muscular layer, with an abscess in one of six rats treated intravenously. After 3 weeks of PDT there was muscular necrosis with perforation and abscess from catheterization two of six rats treated intravesically and in three the bladder wall totally recovered. In the intravenous group the bladder walls were normal or had only mild superficial damage. Cytology of the urine sediment failed to detect half the tumours in the treatment groups. CONCLUSION: These results support the use of PDT with intravesical ALA-induced protoporphyrin X for treating superficial bladder carcinoma. Intravesical was better than intravenous ALA in eradicating bladder carcinoma with PDT.

Is all of the endoplasmic reticulum created equal? The effects of the heterogeneous distribution of endoplasmic reticulum Ca2+-handling proteins.

The endoplasmic reticulum is a heterogeneous compartment with respect to the distribution of its Ca2+-handling proteins, namely the Ca2+-binding proteins, the Ca2+ pumps and the Ca2+ release channels. The nonuniform distribution of these proteins may explain the functional heterogeneity of the endoplasmic reticulum, such as the generation of spatially complex Ca2+ signals, Ca2+ homeostasis, and protein folding and quality control.

Ca2+ signaling and calcium binding chaperones of the endoplasmic reticulum.

The endoplasmic reticulum is a centrally located organelle which affects virtually every cellular function. Its unique luminal environment consists of Ca(2+) binding chaperones, which are involved in protein folding, post-translational modification, Ca(2+) storage and release, and lipid synthesis and metabolism. The environment within the lumen of the endoplasmic reticulum has profound effects on endoplasmic reticulum function and signaling, including apoptosis, stress responses, organogenesis, and transcriptional activity. Calreticulin, a major Ca(2+) binding (storage) chaperone in the endoplasmic reticulum, is a key component of the calreticulin/calnexin cycle which is responsible for the folding of newly synthesized proteins and glycoproteins and for quality control pathways in the endoplasmic reticulum. The function of calreticulin, calnexin and other endoplasmic reticulum proteins is affected by continuous fluctuations in the concentration of Ca(2+) in the endoplasmic reticulum. Thus, changes in Ca(2+) concentration may play a signaling role in the lumen of the endoplasmic reticulum as well as in the cytosol. Recent studies on calreticulin-deficient and transgenic mice have revealed that calreticulin and the endoplasmic reticulum may be upstream regulators in the Ca(2+)-dependent pathways that control cellular differentiation and/or organ development.

Endoplasmic reticulum in the heart, a forgotten organelle?

Our hypothesis is that sarcoplasmic and endoplasmic reticulum Ca2+ stores may be functionally distinct compartments in cardiomyocytes. Sarcoplasmic reticulum Ca2+ store is responsible for control of excitation-contraction coupling whereas endoplasmic reticulum compartment may provide Ca2+ for housekeeping and transcriptional functions.

HSV-tk gene therapy for human renal cell carcinoma in nude mice.

We have treated Caki-2 human renal cell carcinoma in vivo using herpes simplex virus thymidine kinase (HSV-tk) gene therapy. Both stably transduced Caki-2 tumors, generated using retrovirus-mediated ex vivo HSV-tk gene transfer and direct intratumoral adenovirus-mediated HSV-tk gene transfer of wild type tumors, were tested. Similar treatments with LacZ containing retro- and adenoviruses were used as controls. The outcome was evaluated by imaging the tumors before and after the treatment with magnetic resonance imaging, and using histology, immunocytochemistry, and survival analysis. When implanted orthotopically into nude mouse kidneys, Caki-2 cells formed reproducible cystic papillary kidney carcinomas. In vivo magnetic resonance imaging provided an important tool for the evaluation of tumor growth. Transduction efficiency of wild-type tumors in vivo with adeno-LacZ was 22+/-14%. Significant tumor regression was achieved with direct intratumoral adeno-HSV-tk transduction followed by intraperitoneal ganciclovir (GCV) (P<.001). Also, the treatment of stably transduced Caki-2 tumors with intraperitoneal GCV resulted in a significant treatment response in the HSV-tk group as compared to the LacZ group (P<.009). Increased apoptosis and macrophage infiltrations, reduced proliferation, and degenerative changes were observed in the tumors treated with HSV-tk and GCV. Also, significant prolongation in survival was achieved with adeno-HSV-tk- and GCV-treated mice as compared to the controls. It is concluded that adeno-HSV-tk gene therapy may be useful for the treatment of renal cell carcinoma in vivo.

Effect of photodynamic therapy on urinary bladder function: an experimental study with rats.

Photodynamic therapy (PDT) produces localized necrosis with light after prior administration of a photosensitizing drug. The problems with laser light dosimetry and complications relating to bladder function appear to be important limiting factors of PDT in urology. Photodynamic therapy on urinary bladder with normal epithelium of rats was performed using an argon ion laser as an energy source, with aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) photosensitizer. Four hours after ALA intravenous administration, the bladders were intravesically radiated with light doses 20, 40, or 80 J/cm2. Animals in the control group did not receive ALA and were radiated with 20 J/cm2 light dose. Three weeks prior to PDT, the bladder capacity and pressure changes during filling cystometry were assessed. Cystometrics were repeated 1, 3, 7, or 21 days after laser therapy. The light dose 20 J/cm2 and 40 J/cm2 together with the used ALA dose caused no reduction in bladder capacity, whereas 80 J/cm2 light dose produced up to 50% reduction in the capacity at 3 weeks postoperatively. In control group without ALA, the animals did not regain more than 34% of the capacity of their control values at 3 weeks. The light dose of 20 J/cm2 and 40 J/cm2 with ALA induced functional changes that subsided after day 1. Our results indicate that with proper dosing of photosensitizing drug and light energy, the functional impairment of urinary bladder may be reduced as transient. These findings support the use of PDT as safe therapy of superficial bladder cancer.

Two-year follow-up results of a prospective randomized trial comparing hybrid laser prostatectomy with TURP in the treatment of big benign prostates.

OBJECTIVE: We compared conventional transurethral electroresection of the prostate (TURP) and hybrid laser treatment in patients with symptomatic bladder outflow obstruction caused by a benign prostate bigger than 40 ml. MATERIAL AND METHODS: Forty-six patients with symptomatic urodynamically confirmed outflow obstruction caused by benign prostate hyperplasia bigger than 40 ml were accepted to the prospective trial and were randomized to receive hybrid laser treatment or TURP. The hybrid laser technique involved initial non-contact Nd:YAG coagulation followed by contact Nd:YAG vaporization to open the prostatic urethra. Patients were re-assessed after 3, 6, 12 and 24 months. RESULTS: Of the 46 patients, 37 (80%) were available at the 24-month follow-up. The re-operation rate was 14.3% in the hybrid laser group and 8.3% in the TURP group. The decrease in DanPSS-1 symptom score from baseline at 24 months was 51.0% in the hybrid laser group (p<0.01) and 80.0% in the TURP group (p<0.001), with no statistically significant differences between the groups. Early improvement in objective urinary parameters of peak urinary flow rate and residual urinary volume showed deterioration in hybrid laser group during longer follow-up, whereas in TURP group the improvement of these variables was sustained. Comparison between groups showed TURP to be superior in peak urinary flow rate (p < 0.001) and residual urinary volume (p < 0.01) at the 24-month follow-up visit. CONCLUSIONS: Both hybrid laser treatment and TURP give good symptomatic relief lasting at least 2 years in the treatment of big obstructing prostates, but hybrid laser treatment is associated with a higher re-operation rate because of inadequate initial prostate tissue removal and with inferior outcome in objective urinary parameters compared with TURP.

Functional specialization of calreticulin domains.

Calreticulin is a Ca2+-binding chaperone in the endoplasmic reticulum (ER), and calreticulin gene knockout is embryonic lethal. Here, we used calreticulin-deficient mouse embryonic fibroblasts to examine the function of calreticulin as a regulator of Ca2+ homeostasis. In cells without calreticulin, the ER has a lower capacity for Ca2+ storage, although the free ER luminal Ca2+ concentration is unchanged. Calreticulin-deficient cells show inhibited Ca2+ release in response to bradykinin, yet they release Ca2+ upon direct activation with the inositol 1,4,5-trisphosphate (InsP3). These cells fail to produce a measurable level of InsP3 upon stimulation with bradykinin, likely because the binding of bradykinin to its cell surface receptor is impaired. Bradykinin binding and bradykinin-induced Ca2+ release are both restored by expression of full-length calreticulin and the N + P domain of the protein. Expression of the P + C domain of calreticulin does not affect bradykinin-induced Ca2+ release but restores the ER Ca2+ storage capacity. Our results indicate that calreticulin may play a role in folding of the bradykinin receptor, which affects its ability to initiate InsP3-dependent Ca2+ release in calreticulin-deficient cells. We concluded that the C domain of calreticulin plays a role in Ca2+ storage and that the N domain may participate in its chaperone functions.

Formation of retinal pigment epithelium in vitro by transdifferentiation of neural retina cells.

Chick embryonic neural retina (NR) dedifferentiates in culture and can transdifferentiate spontaneously into retinal pigment epithelium (RPE). Both, primary RPE and transdifferentiated RPE (RPEt), are characterized by pigmentation, expression of RPE-specific protein, eRPEAG and lack of expression of the neural cell adhesion molecule, NCAM. In contrast, NR cells are unpigmented and express NCAM but not eRPE(AG). Functionally, both primary RPE and the RPEt cells display a pH(i) response to bFGF, which is different from that of the NR. We used these characteristics to distinguish cell types in primary cultures of chick NR and follow the changes in phenotype that occur during transdifferentiation. We show that the RPEt forms as small "islands" in the packed regions of the primary, "mother" NR cell sheets, in a stochastic process. Because of a small number of cells involved in the initiation of the transdifferentiation we refer to it as a "leader effect" to contrast it with the "community effect" which requires many competent cells to be present in a group to be able to respond to an inductive signal. The RPEt then expands centrifugally and underneath the surrounding NR sheet. To determine if the RPEt maintains its identity in isolation while displaying the RPE-typical phenotypic plasticity, we explanted the islands of RPEt and treated half of them with bFGF. The untreated RPEt maintained its closely packed, polygonal pigmented phenotype but the bFGF-treated RPEt transdifferentiated into a non-pigmented, NR-like phenotype, indicating that RPEt encompasses the full differentiation repertoire of native RPE.