Hemigland Cryoablation of Localized Low, Intermediate and High Risk Prostate Cancer: Oncologic and Functional Outcomes at 5 Years.

PURPOSE: We evaluated 5-year oncologic and functional outcomes of hemigland cryoablation of localized prostate cancer. MATERIALS AND METHODS: We reviewed the records of 160 consecutive men who underwent hemigland cryoablation of localized prostate cancer. Recurrent and/or residual clinically significant prostate cancer was defined as Grade Group 2 or greater on followup biopsy. A prostate specific antigen nadir plus 2 ng/ml according to the Phoenix criteria was used to define biochemical failure. Radical treatment was defined as any whole gland therapy. Treatment failure was defined as any radical and/or whole gland treatment, systemic therapy initiation, metastasis or prostate cancer specific mortality. The study primary end point was treatment failure-free survival. The secondary end points were survival free of biochemical failure, clinically significant prostate cancer and radical treatment. Followup biopsy and functional outcomes were also evaluated. Statistical analysis included the Kaplan-Meier method, and univariate and multivariable Cox and logistic regression with significance considered at p <0.05. RESULTS: Median patient age was 67 years, baseline prostate specific antigen was 6.3 ng/ml and followup was 40 months. A total of 131 patients (82%) had D'Amico intermediate (66%) or high risk (16%) prostate cancer. At 5 years the treatment failure-free survival rate was 85%, the biochemical failure-free survival rate was 62% and the survival rate free of clinically significant prostate cancer was 89%. Higher baseline prostate specific antigen independently predicted treatment failure (p <0.001), biochemical failure (p=0.048), recurrence and radical treatment (p <0.01). Grade Group 3 or greater independently predicted treatment failure (p=0.04). The metastasis-free survival rate was 100% at 5 years. Pad-free continence and potency (erections sufficient for intercourse) were retained in 97% and 73% of patients, respectively. There was no rectal fistula or mortality. CONCLUSIONS: Hemigland cryoablation of localized prostate cancer provides effective midterm oncologic outcomes with good continence and potency. Patients with higher baseline prostate specific antigen are at increased risk for biochemical failure, recurrent cancer and treatment failure.

Primary Whole-gland Cryoablation for Prostate Cancer: Biochemical Failure and Clinical Recurrence at 5.6 Years of Follow-up.

We retrospectively evaluated complications and functional and oncologic outcomes of 94 consecutive men who underwent primary whole-gland cryoablation for localized prostate cancer (PCa) from 2002 to 2012. Kaplan-Meier and multivariable Cox regression analyses were performed using a landmark starting at 6 mo of follow-up. In total, 75% patients had D'Amico intermediate- (48%) or high- (27%) risk PCa. Median follow-up was 5.6 yr. Median time to prostate-specific antigen (PSA) nadir was 3.3 mo, and 70 patients reached PSA <0.2ng/ml postcryoablation. The 90-d high-grade (Clavien Grade IIIa) complication rate was 3%, with no rectal fistulas reported. Continence and potency rates were 96% and 11%, respectively. The 5-yr biochemical failure-free survival (PSA nadir+2ng/ml) was 81% overall and 89% for low-, 78% for intermediate-, and 80% for high-risk PCa (p=0.46). The median follow-up was 5.6 and 5.1 yr for patients without biochemical failure and with biochemical failure, respectively. The 5-yr clinical recurrence-free survival was 83% overall and 94% for low-, 84% for intermediate-, and 69% for high-risk PCa (p=0.046). Failure to reach PSA nadir <0.2ng/ml within 6 mo postcryoablation was an independent predictor for biochemical failure (p=0.006) and clinical recurrence (p=0.03). The 5-yr metastases-free survival was 95%. Main limitation is retrospective evaluation. Primary whole-gland cryoablation for PCa provides acceptable medium-term oncologic outcomes and could be an alternative for radiation therapy or radical prostatectomy. PATIENT SUMMARY: Cryoablation is a safe, minimally-invasive procedure that uses cold temperatures delivered via probes through the skin to kill prostate cancer (PCa) cells. Whole-gland cryoablation may offer an alternative treatment option to surgery and radiotherapy. We found that patients had good cancer outcomes 5 yr after whole-gland cryoablation, and those with a prostate-specific antigen value ≥0.2ng/ml within 6 mo after treatment were more likely to have PCa recurrence.

Symmetry analysis of talus bone: A Geometric morphometric approach.

OBJECTIVE: The main object of this study was to use a geometric morphometric approach to quantify the left-right symmetry of talus bones. METHODS: Analysis was carried out using CT scan images of 11 pairs of intact tali. Two important geometric parameters, volume and surface area, were quantified for left and right talus bones. The geometric shape variations between the right and left talus bones were also measured using deviation analysis. Furthermore, location of asymmetry in the geometric shapes were identified. RESULTS: Numerical results showed that talus bones are bilaterally symmetrical in nature, and the difference between the surface area of the left and right talus bones was less than 7.5%. Similarly, the difference in the volume of both bones was less than 7.5%. Results of the three-dimensional (3D) deviation analyses demonstrated the mean deviation between left and right talus bones were in the range of -0.74 mm to 0.62 mm. It was observed that in eight of 11 subjects, the deviation in symmetry occurred in regions that are clinically less important during talus surgery. CONCLUSIONS: We conclude that left and right talus bones of intact human ankle joints show a strong degree of symmetry. The results of this study may have significance with respect to talus surgery, and in investigating traumatic talus injury where the geometric shape of the contralateral talus can be used as control. Cite this article: Bone Joint Res 2014;3:139-45.

Primary androgen deprivation (AD) followed by active surveillance (AS) for newly diagnosed prostate cancer (PC): A retrospective study.

BACKGROUND: Active surveillance (AS) is only recommended for Low-Risk prostate cancer (PC) with <34% biopsies positive. Studies describing the long-term outcome of men treated with androgen deprivation (AD) followed by AS are sparse. MATERIALS AND METHODS: One hundred two men were treated with 12 months of AD in a medical oncology clinic specializing in PC between 1998 and 2007 and were followed for a median of 7.25 years. The biopsy complete response rate after AD and the incidence of disease progression while on subsequent AS was assessed. Baseline age, D'Amico risk category, PSA velocity, percentage core biopsies, and prostate volume were evaluated as potential predictors of disease progression. RESULTS: D'Amico risk category for the 102 men: Low: n = 22, Intermediate: n = 30, and High: n = 50. Medians: Age 67.3, PSA 7.8, Gleason 3 + 4, >50% core biopsies positive, stage T1c. Seventy men had a clear biopsy and 31 of these had disease progression leading to additional treatment after a median of 52 months. D'Amico risk category of the 57 men with a positive biopsy after AD or disease progression on AS was: Low: n = 4 (18%), Intermediate: n = 16 (53%), and High: n = 37 (74%). No PC deaths occurred. Three men had clinical progression. In stepwise logistic regression analysis only higher D'Amico risk category and lower prostate volume predicted disease progression. CONCLUSIONS: Despite a high prevalence of ≥50% core biopsies positive at baseline, AD induces durable remissions in most men with Low-Risk and about half with Intermediate-Risk PC.

Enteric-coated cysteamine for the treatment of paediatric non-alcoholic fatty liver disease.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is a common cause of liver disease in children. Hepatic fat accumulation and oxidative stress contribute to its pathogenesis. Cysteamine bitartrate readily traverses cellular membranes and is a potent antioxidant. AIM: To evaluate the safety and efficacy of enteric-coated (EC) cysteamine in children with NAFLD. METHOD: Children, aged ≥10 y, meeting screening criteria with biopsy-proven NAFLD and serum ALT ≥60 IU/L, received twice-daily EC-cysteamine for 24 weeks. Monthly ALT, AST, body mass index (BMI) and gastrointestinal symptom scores were measured. Subjects with >50% reduction or normalisation of ALT achieved the primary endpoint. RESULTS: Of the 13 children enrolled (mean age 14.0 years), 11 completed EC-cysteamine therapy (mean dose 15.2 mg/kg/day) and were included in the final analysis. For these 11 subjects, the mean ALT levels at baseline and 24 weeks were 120.2 and 55 IU/L respectively (P = 0.002), and the AST levels were 60 and 36 IU/L respectively (P = 0.007). The primary endpoint was reached in 7 and normalisation (≤40 IU/L) of ALT in 5. After 24 week therapy, mean adiponectin levels increased (P = 0.009) and CK-18 fragment levels decreased (P = 0.013), insulin levels remained unchanged (P = 0.99). Mean leptin levels were decreased in responders (P = 0.044). Mean BMI was 34.5 at baseline and 34.2 kg/m(2) after treatment (P = 0.35). Mean symptom scores at baseline (1.1) and at 24 weeks (0.7) were similar. No major adverse events were reported. CONCLUSIONS: Enteric-coated cysteamine reduces ALT and AST levels in children with NAFLD without reduction in body mass index. Further studies will evaluate optimal cysteamine therapeutic dose and effect on liver histology in NAFLD (Clinicaltrials.gov protocol ID: 07-1699).

Focal cryoablation of prostate: a review.

Current treatment options for men with early localized prostate cancer are either some form of radical therapy or active surveillance. Radical therapy is usually associated with significant adverse effects that might jeopardize a man's quality of life. Some observers believe that PSA screening has resulted in the over diagnosis and over treatment of prostate cancer. Many men are being diagnosed with an early stage, small volume, unifocal or unilateral prostate cancer but are reluctant to accept watchful waiting or active surveillance. Focal cryoablation is the less than complete ablation of the gland with ice. Based on review of the limited amount of material available in the current literature, focal cryoablation can provide acceptable cancer control while preserving sexual potency and urinary continence. Focal cryoablation may fill a void in the therapeutic options available to patients with unifocal or unilateral prostate cancer who have a strong desire to maintain their quality of life.

Focal prostate cryoablation: initial results show cancer control and potency preservation.

BACKGROUND: Focal prostate cryoablation is the less-than-complete ablation of the gland with ice. Known tumor is ablated aggressively, whereas contralateral prostate tissue and surrounding structures are spared. This method offers targeted local cancer control aiming at sexual potency and urinary continence preservation in patients whose prostate cancer is believed to be unilateral. PATIENTS AND METHODS: Patients who had a strong desire for preservation of sexual function and continence were informed of focal prostate cryoablation as an investigational treatment option for clinically organ-confined, unilateral tumor identified by color Doppler ultrasonography and confirmed by targeted and systematic biopsy. Only stage, not preoperative serum prostate specific antigen concentration (PSA) or tumor differentiation, was considered a potential contraindication. Thirty-one men with a mean age of 63 years underwent the procedure. Follow-up consisted of PSA measurement every 3 months for 1 year and every 6 months thereafter, with biopsies at 6 months and 1, 2, and 5 years and following any three consecutive PSA rises. Potency was determined with a patient questionnaire filled in without the physician present. RESULTS: At a mean follow-up of 70 months, biochemical disease-free status, according to the ASTRO definition, was maintained by 92.8% of patients (26/28) and a 96.0% negative-biopsy rate (24/25) was observed. The one biopsy-positive patient was subsequently treated with full-gland cryoablation and remains disease free. Potency was maintained by 48.1% of patients (13/27) and another 40.7% (11/27) were potent with oral pharmaceutical assistance, yielding a total potency-preservation rate of 88.9%. No complications were observed. CONCLUSION: Focal cryoablation can provide biochemical and local control of prostate cancer while preserving potency and continence. Further investigation is needed.

Constant infusion of epinephrine, but not bolus treatment, improves haemodynamic recovery in anaphylactic shock in dogs.

OBJECTIVE: Epinephrine (Epi) is the treatment of choice for reversing cardiovascular collapse in anaphylactic shock (AS). In this condition, most treatment guidelines have been anecdotally derived and no randomized clinical trials have been conducted. In the present study, we examined the time course of haemodynamic recovery in a canine model of AS when Epi was administered at the initiation of allergen challenge before fully developed shock had occurred. METHODS: Randomized, controlled, crossover studies were performed approximately 3-5 weeks apart in ragweed-sensitized dogs while the animals were ventilated and anaesthetized. Epi was administered by bolus intravenous (i.v.), subcutaneous (s.c.), intramuscular (i.m.) routes and by continuous i.v. infusion (CI). The findings obtained in the Epi treatment (T) studies were compared with those found in a no treatment (NT) study. In the bolus studies, Epi was administered at 0.01 mg/kg, while in the CI study, the dose of Epi was titrated to maintain mean arterial pressure (MAP) at 70% of preshock levels. MAP, cardiac output (CO), stroke volume (SV), and pulmonary wedge pressure (Pwp) were determined over a 3 h period. RESULTS: In the CI study, haemodynamics (CO, MAP, and SV) were significantly higher than those measured in the NT study and the bolus studies over approximately the first hour of the study. In the CI study, the amount of Epi infused was significantly less than in the bolus studies. CONCLUSION: When administered at the initiation of allergen challenge, bolus treatment of Epi by i.m., i.v., or s.c. routes caused limited haemodynamic improvement in AS. In contrast, constant infusion of Epi at a lower total dose produced significant haemodynamic improvement. Within the limits of this anaesthetized canine model, the results suggest that CI should be the preferred route in the treatment of AS when this treatment option is available.

In treating localized prostate cancer the efficacy of cryoablation is independent of DNA ploidy type.

While the prognostic value of DNA ploidy has been well established for radical prostatectomy, external beam radiation, brachytherapy and androgen deprivation therapy its role as a survival outcome predictor for prostate cancer patients treated with cryoablation has not yet been examined. Anecdotal evidence suggesting that cryoablation may be independent of DNA ploidy type led to the implementation of the current study. Retrospective analysis of data including flow digital cytometry was performed on 447 archival specimens taken from patients who had undergone cryosurgical ablation of primary prostate cancer. Five-year biochemical disease free survivals (bDFS) (defined as PSA thresholds of 0.5 and 1.0 ng/ml) were determined with Kaplan-Meier analysis. Patients were grouped according to DNA ploidy types then stratified by Gleason grade, risk group, pre-surgical PSA level, and disease stage. Mean and median age of the cohort was 65 and 64.6 years. Mean follow-up was 65.7 months. The DNA ploidy status of the population was found to be 59% diploid, 13% tetraploid, and 28% aneuploid. Using PSA < 1.0 ng/ml criterion, the bDFS rates for diploid, tetraploid, and aneuploid were 78%, 75%, and 79% respectively. The bDFS rates using a PSA < 0.5 ng/ml criterion were 67%, 59%, and 69% for diploid, tetraploid, and aneuploid groups. No significant outcome differences were found in stratified analysis. This investigation demonstrates that the efficacy of cryoablation is independent of DNA ploidy type.

Identification and characterization of peptide probes directed against PKCalpha conformations.

Phage display is a powerful technology that allows identification of high affinity peptides that bind specifically to a given molecular target. Using a highly complex peptide display library, we have identified separate classes of peptides that bind to protein kinase C alpha (PKCalpha) only under activation conditions. Furthermore, peptide binding was specific to PKCalpha and not to any of the other closely related PKC isoforms. The conformational and isoform specificity of the peptide binding was demonstrated using surface plasmon resonance as well as time-resolved fluorescence assays. Kinase assays showed that these peptides were not direct substrates for PKC nor did they inhibit phosphorylation of PKC substrates. These peptides are most likely directed against protein-protein interaction sites on PKC. The data presented here offers another example of application of phage display technology to identify conformation-dependent peptide probes against therapeutically important drug targets. These peptides are ideally suited to be used as surrogate ligands to identify compounds that bind specifically to PKCalpha, as well as conformational probes to detect activated forms of PKCalpha.

Salvage cryosurgery for recurrent prostate cancer after radiation therapy: a seven-year follow-up.

Cryosurgery of the prostate presents as an efficient therapy following failed radiation therapy. We report on a 7-year retrospective analysis evaluating the morbidity adn biochemical disease-free survival(bDFS) of this therapy. Between 1993 and 2001, 59 patients who had been previously treated with radiation therapy and had rising serum prostate-specific antigen(PSA) values underwent salvage cryoablation of the prostate for localized, histologically proven, recurrent prostate cancer. Serial serum PSA testing was performed, and biopsies were taken at 6, 12, and 24 months, and again at 5 years, and any time the PSA rose above 0.5 ng/mL. Patients were stratified along clinical parameters. The combined postsalvage bDFS rate using a PSA cutoff of 0.5 ng/mL was 59% and 69% with a 1.0 ng/mL PSA cut off. Using a PSA threshold of 0.5 ng/mL as evidence of biochemical recurrence, 61%, 62%, and 50% of patients with <4 ng/mL, 4-10 ng/mL, and > 10 ng/mL PSA, respectively, remain biochemically relapse free at 7 years. A threshold of 1.0 ng/mL yielded a disease-free status of 78%, 74%, and 46% respectively. Patients biopsies showed no evidence of residual or recurrent disease. Improved survival rates and no known latent complications indicate cryosurgery is a promising form of treatment for radiation-resistant prostate cancer. This 7-year analysis shows a promising validation of cryosurgery as an efficacious treatment modality for locally confined T1-T3 prostate cancer following primary radiation therapy failure.

Targeted cryoablation of the prostate: 7-year outcomes in the primary treatment of prostate cancer.

The efficacy and safety of the long-term experience with targeted cryoablation of prostate cancer (TCAP) at a community hospital is retrospectively reviewed. A series of 590 consecutive patients who underwent TCAP as primary therapy with curative intent for localized or locally advanced prostate cancer from March 1993 to September 2001 were identified. Patients were stratified into 3 risk groups according to clinical characteristics. Biochemical disease-free survival (bDFS), post-TCAP biopsy results, and post-TCAP morbidity were calculated and presented. The mean follow-up time for all patients was 5.43 years. The percentages of patients in the low-, medium-, and high-risk groups were 15.9%, 30.3%, and 53.7%, respectively. Using a prostate-specific antigen (PSA)-based definition of biochemical failure of 0.5 ng/mL, results were as follows: (1) the 7-year actuarial bDFS for low-, medium-, and high-risk patients were 61%, 68%, and 61%, respectively; (2) the bDFS probabilities for a PSA cutoff of 1.0 ng/mL for low-, medium-, and high-risk patients were 87%, 79%, and 71%, respectively; and (3) the bDFS probabilities for low-, medium-, and high-risk patients using the American Society for Therapeutic Radiology and Oncology (ASTRO) definition of biochemical failure (3 successive increases of PSA level) were 92%, 89%, and 89%, respectively. The rate of positive biopsy was 13%. After a positive biopsy, 32 patients underwent repeat cryoablation. For those patients who underwent repeat cryoablation, 68%, 72%, and 91% remain bDFS using definitions of 0.5 ng/mL, 1.0 ng/mL, and the ASTRO criteria, respectively, after a mean follow-up time since repeat cryoablation of 63 months. The rates of morbidity were modest, and no serious complications were observed. TCAP was shown to equal or surpass the outcome data of external-beam radiation, 3-dimensional conformal radiation, and brachytherapy. These 7-year outcome data provide compelling validation of TCAP as an efficacious treatment modality for locally confined and locally advanced prostatic carcinoma.

Computer modelling of hooks for use as intra-operative force sensors.

There are a number of forces applied during scoliosis surgery, the magnitude and direction of which remains unknown. There is little literature concerning the in vivo distribution of forces along the spine. Computer modelling (ANSYS) was used to investigate the possibility of using an instrumented hook to intra-operatively measure the antero-posterior and distraction/compression forces applied by the surgeon during corrective scoliosis surgery. Three hook designs were evaluated based on specific design criteria. ANSYS provided the preliminary analysis to determine the strain distribution in these hooks. One design, the "membrane" design, was selected and a prototype was manufactured. Preliminary tests demonstrate that this prototype will be able to differentiate between the four major forces applied during the surgical correction.

Study of patient positioning on a dynamic frame for scoliosis surgery.

The goal of this clinical trial was to measure patient geometry on a dynamic positioning frame in various prone positions. Fourteen subjects (2 males and 12 females) were recruited from the scoliosis clinic at Ste-Justine Hospital on a volunteer basis. The subjects were AIS patients who were potential candidates for surgery. The Cobb angle, averaged 50 degrees (32 degrees-64 degrees). The mean age was 14.1 years (11-17). A Polaris system (Northern Digital inc, Canada) with 10 passive reflective markers was used to measure various indices of the patient's trunk geometry. Acquisitions were made while the unanaesthetized patient was in five different prone positions: I similar to the standard positioning on a Relton-Hall frame; II addition of a force applied to the ribcage at the apex of the curve; III application of a force at the apex of the curve in the lumbar region; IV, the shoulder pads were elevated to increase the patient's kyphosis; V adjustment of each pad and the application of thoracic and lumbar forces to obtain an optimal correction. The measurements of trunk geometry at each position were compared using position I as a base. A paired student t-test determined a significant difference between positions. When comparing position I to position II there was a significant difference and correction of the rib hump. There was also a significant change in shoulder angle that resulted in over correction. Position III had a significantly negative change in the rib hump. During position IV, there was a measurable increase in kyphosis. During the optimal correction, position V, a significant increase in spine length was observed as well as a significant correction in rib hump and shoulder angle. Patient trunk geometry can be improved by the application of different forces on a dynamic positioning frame. Caution is necessary as over correction and unintended negative effects were observed. The optimal patient position has not yet been found and future studies are directed at determining this.

A gene expression map for Caenorhabditis elegans.

We have assembled data from Caenorhabditis elegans DNA microarray experiments involving many growth conditions, developmental stages, and varieties of mutants. Co-regulated genes were grouped together and visualized in a three-dimensional expression map that displays correlations of gene expression profiles as distances in two dimensions and gene density in the third dimension. The gene expression map can be used as a gene discovery tool to identify genes that are co-regulated with known sets of genes (such as heat shock, growth control genes, germ line genes, and so forth) or to uncover previously unknown genetic functions (such as genomic instability in males and sperm caused by specific transposons).

Humicola insolens cellobiose dehydrogenase: cloning, redox chemistry, and "logic gate"-like dual functionality.

1Cellobiose dehydrogenase is a hemoflavoenzyme that catalyzes the sequential electron-transfer from an electron-donating substrate (e.g. cellobiose) to a flavin center, then to an electron-accepting substrate (e.g. quinone) either directly or via a heme center after an internal electron-transfer from the flavin to heme. We cloned the dehydrogenase from Humicola insolens, which encodes a protein of 761 amino acid residues containing an N-terminal heme domain and a C-terminal flavin domain, and studied how the catalyzed electron transfers are regulated. Based on the correlation between the rate and redox potential, we demonstrated that with a reduced flavin center, the enzyme, as a reductase, could export electron from its heme center by a "outer-sphere" mechanism. With the "resting" flavin center, however, the enzyme could have a peroxidase-like function and import electron to its heme center after a peroxidative activation. The dual functionality of its heme center makes the enzyme a molecular "logic gate", in which the electron flow through the heme center can be switched in direction by the redox state of the coupled flavin center.

A novel carbohydrate:acceptor oxidoreductase from Microdochium nivale.

A Microdochium nivale carbohydrate:acceptor oxidoreductase was purified, cloned, heterologously expressed, and characterized. The gene encoding the protein showed one intron, and the ORF showed a sequence with low homology (< or = 25% identity or 65% similarity) to other known flavin-containing carbohydrate oxidases. The maturation of the protein required the cleavage of a tetrameric propeptide in addition to an 18 amino-acid signal peptide. The enzyme was found to have a relative molecular mass of 55 000 Da, an isoelectric point of 9, and one FAD per protein. It could oxidize mono-, oligo-, or polymeric saccharides, and transfer their electrons to O2 or other acceptors. When D-glucose served as electron-donating substrate, an activity of 2 s(-1) was observed at pH 5.5 and 23 degrees C. Among various oligosaccharides, the enzyme preferred tetrameric dextrins, indicating a favorable interaction of four linked glucose units with the substrate pocket. The unique structure and ability of oxidizing oligo/polymeric saccharides suggest a promising prospect of this enzyme for various industrial/medicinal applications.

Genome-wide analysis of developmental and sex-regulated gene expression profiles in Caenorhabditis elegans.

We have constructed DNA microarrays containing 17,871 genes, representing about 94% of the 18,967 genes currently annotated in the Caenorhabditis elegans genome. These DNA microarrays can be used as a tool to define a nearly complete molecular profile of gene expression levels associated with different developmental stages, growth conditions, or worm strains. Here, we used these full-genome DNA microarrays to show the relative levels of gene expression for nearly every gene during development, from eggs through adulthood. These expression data can help reveal when a gene may act during development. We also compared gene expression in males to that of hermaphrodites and found a total of 2,171 sex-regulated genes (P < 0.05). The sex-regulated genes provide a global view of the differences between the sexes at a molecular level and identify many genes likely to be involved in sex-specific differentiation and behavior.

Impaired sarcoplasmic calcium release inhibits myocardial contraction in experimental sepsis.

PURPOSE: In septic shock, myocardial dysfunction develops over the course of illness, but the mechanism of this depression is not clear. In this study, mechanisms of myocardial dysfunction were examined in a porcine model of Escherichia coli sepsis. MATERIALS AND METHODS: Animals were subjected to 4 hours of bacteria infusion (n = 5) (septic group) or saline infusion (n = 5) (nonseptic group), after which trabeculae were removed from the right ventricle and placed into a recirculating water bath. Measurements of steady-state contraction (SSC) were obtained at 0.5, 1, and 2 Hz. Indirect indices were used to assess abnormalities in myocardial calcium metabolism in sepsis. Extrasystoles (ES) were used to assess transsarcolemmal (TSL) calcium flux and were measured at 300 milliseconds, 400 milliseconds, and 500 milliseconds after the preceding stimulus. Postrest contraction (PRC) is an indicator of SR recirculation from the uptake to the release site and was obtained after interposing intervals of rest between steady-state beats at 0.5 Hz. Rapid-cooling contracture (RCC) is an indicator of sarcoplasmic reticulum (SR) content and was obtained at 0.5, 1, and 2 Hz and after interposing intervals of rest at 0.5 Hz. RESULTS: SSC was not different between groups at 0.5 Hz, but compared with the nonseptic group, SSC decreased at 1 and 2 Hz in the septic group (P < .05). PRC and TSL were not different between groups. During rest intervals, calcium leaks out of SR through the ryanodine channel (ie, SR calcium release channel). In the septic group, as assessed by RCC, SR calcium leak was less than that found in the nonseptic group. CONCLUSION: These results indicate that myocardial dysfunction in sepsis is frequency dependent, and that the mechanism is most likely caused by inhibition of SR calcium release owing to blockade of the ryanodine channel.