Luminal Ca2+ regulation of RyR1 Ca2+ channel leak activation and inactivation in sarcoplasmic reticulum membrane vesicles.

In this study, we tested the hypothesis that the RyR1 Ca2+ channel closure is sensitive to outward trans-SR membrane Ca2+ gradients established by SERCA1 pumping. To perform these studies, we employed stopped-flow rapid-kinetic fluorescence methods to measure and assess how variation in trans-SR membrane Ca2+ distribution affects evolution of RyR1 Ca2+ leaks in RyR1/ CASQ1/SERCA1-rich membrane vesicles. Our studies showed that rapid filling of a Mag-Fura-2-sensitive free Ca2+ pool during SERCA1-mediated Ca2+ sequestration appears to be a crucial condition allowing RyR1 Ca2+ channels to close once reloading of luminal Ca2+ stores is complete. Disruption in the filling of this pool caused activation of Ruthenium Red inhibitable RyR1 Ca2+ leaks, suggesting that SERCA1 pump formation of outward Ca2+ gradients is an important aspect of Ca2+ flux control channel opening and closing. In addition, our observed ryanodine-induced shift in luminal Ca2+ from free to a CTC-Ca+-sensitive, CASQ1-associated bound compartment underscores the complex organization and regulation of SR luminal Ca2+. Our study provides strong evidence that RyR1 functional states directly and indirectly influence the compartmentation of luminal Ca2+. This, in turn, is influenced by the activity of SERCA1 pumps to fill luminal pools while synchronously reducing Ca2+ levels on the cytosolic face of RyR1 channels.

Consumer experiences of shame in clinical encounters for breast cancer treatment. "Who do you think you are- Angelina Jolie?"

BACKGROUND: Shame is a powerful negative emotion that has the potential to affect health. Due to the intimate nature of breast cancer treatment and its impact on body image, it is hypothesised that shame may be experienced during treatment. The aim of this study was to explore shame experiences related to clinical encounters for breast cancer treatment. METHODS: People with a lived experience of breast cancer were invited to anonymously share their stories of shame through an online survey. Using qualitative methodology, the stories were examined, and themes identified. PARTICIPANTS: Participants were members of the consumer organisation Breast Cancer Network Australia. RESULTS: Stories were contributed by 38 participants. Most (n = 28, 73.7 %) were >5 years post-diagnosis. Shame was experienced in a range of clinical settings (consulting rooms, wards, operating theatres, radiotherapy departments). They involved a different health professionals (oncologists, surgeons, nurses, radiation therapists, psychologists.) Five themes were identified: (1) Body shame (sub-themes: Naked/vulnerable and Weight), (2) Communication (subthemes: Lack of compassion/impersonal manner and Not listening), (3) Being blamed (subthemes: diagnosis and complications), (4) Feeling unworthy (subthemes: Burden to staff and Unworthy of care), (5) Judgement for treatment choices. CONCLUSIONS: Shame can be experienced in a range of situations, from scrutiny of the naked body to comments from health professionals. The impact of these experiences is profound, and the feelings of shame are carried for many years. These findings can inform strategies to support consumers and educate health professionals with the aim of reducing harm related to cancer treatment.

Comparison of three assays for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in SurePath Pap samples and the role of pre- and postcytology testing.

Chlamydia trachomatis and Neisseria gonorrhoeae are common causes of sexually transmitted infections, and there is interest in screening SurePath liquid-based Pap (L-Pap) samples with Aptima Combo 2 (AC2), Amplicor (AMP), and ProbeTec ET (PT) assays. SurePath L-Pap samples and a cervical swab (CS) were collected from 394 women attending health clinics in Hamilton and Toronto, ON, Canada. L-Pap samples were tested with the three assays prior to being processed for cytology, and the CS sample was tested with AC2. The prevalence of C. trachomatis was 8.9%, and that of N. gonorrhoeae was 1.5%. By using the positives from CS testing, as well as CS negatives corresponding to L-Pap samples that tested positive in 2 of 3 assays, the sensitivities of AC2, AMP, and PT for C. trachomatis in precytology samples were calculated to be 97.1% (34 of 35 positive samples were detected), 91.4% (32 of 35 were detected), and 77.1% (27 of 35 were detected), respectively. Six women were infected with N. gonorrhoeae. After cytology processing, the results of testing the remaining liquid in the L-Pap vial and the cell-enriched fraction for C. trachomatis by AC2 showed positive agreements of 98.9% (kappa [k], 0.93) and 98.7% (k, 0.92), respectively, with the results of testing precytology L-Pap samples. Although all testing showed high specificity, testing for C. trachomatis by AC2 was significantly more sensitive than testing by PT for SurePath samples (P = 0.02). Newer versions of AMP (Cobas 4800) and PT (Q(x) with XTR technology) need published evaluations for detecting C. trachomatis and N. gonorrhoeae in L-Pap samples. C. trachomatis testing can be performed with similar results on pre- and postcytology SurePath samples.

The cost of dominance: suppressing subordinate reproduction affects the reproductive success of dominant female banded mongooses.

Social species show considerable variation in the extent to which dominant females suppress subordinate reproduction. Much of this variation may be influenced by the cost of active suppression to dominants, who may be selected to balance the need to maximize the resources available for their own offspring against the costs of interfering with subordinate reproduction. To date, the cost of reproductive suppression has received little attention, despite its potential to influence the outcome of conflict over the distribution of reproduction in social species. Here, we investigate possible costs of reproductive suppression in banded mongooses, where dominant females evict subordinates from their groups, thereby inducing subordinate abortion. We show that evicting subordinate females is associated with substantial costs to dominant females: pups born to females who evicted subordinates while pregnant were lighter than those born after undisturbed gestations; pups whose dependent period was disrupted by an eviction attained a lower weight at independence; and the proportion of a litter that survived to independence was reduced if there was an eviction during the dependent period. To our knowledge, this is the first empirical study indicating a possible cost to dominants in attempting to suppress subordinate breeding, and we argue that much of the variation in reproductive skew both within and between social species may be influenced by adaptive variation in the effort invested in suppression by dominants.

Pili on meningococci from primary cultures of nasopharyngeal carriers and cerebrospinal fluid of patients with acute disease.

The nasopharynx of known meningococcal carriers without signs of acute meningococcal disease as well as cerebrospinal fluid from patients with acute meningococcal disease were cultured on Thayer-Martin agar. Pili were observed in negatively stained preparations of over 80% cells from all primary cultures of both nasopharnyx and cerebrospinal fluids. Although pili were abundant on cells from all primary cultures, all pili were lost on serial subculture in the laboratory. This loss of pili from the cell surface on laboratory subculture was not accompanied by a concomitant loss of cell wall blebs.

Release of endotoxin in the form of cell wall blebs during in vitro growth of Neisseria meningitidis.

Multiple cell wall blebs were observed on the surface of three strains of N. meningitidis taken from log phase cultures. The blebs originated as evaginations of the outer layer of the cell wall. Bleb production was noted on both defined or complex media either as broth or a solid medium. The addition of 10% normal bovine serum to the various media did not affect the production and release of these surface blebs. However, as broth cultures progressed into the stationary phase of growth, the blebs disappeared from the surface of the cells. Blebs were present in substantial quantities in culture supernatant fluids and on cell surfaces and were readily isolated by ultracentrifugation. Analysis for 2-keto-3-deoxyoctonate in cultures revealed that 18% of the total endotoxin of log phase cultures was present in blebs from the cell wall.

Mixing and segregation of microspheres in microchannel flows of mono- and bidispersed suspensions.

We investigate the mixing and segregation of mono- and bidispersed microsphere suspensions in microchannel flows. These flows are common in biological microelectromechanical systems (BioMEMS) applications handling blood or suspensions of DNA. Suspension transport in pressure driven flows is significantly hindered by shear-induced migration, where particles migrate away from the walls and are focused in the center due to multibody hydrodynamic interactions. The microchannels used in this study have geometries that induce chaotic advection in Newtonian fluids. Our results show that mixing in straight, herringbone and staggered herringbone channels depends strongly on volume fraction. Due to this complex interplay of advection and shear-induced migration, a staggered herringbone channel that typically results in chaotic mixing is not always effective for dispersing particles. The maximum degree of segregation is observed in a straight channel once the maximum packing fraction is reached at channel center. We modify a one-dimensional suspension balance model [R. Miller and J. Morris, J. Non-Newtonian Fluid Mech. 135, 149 (2006)] to describe the behavior at the center of the straight channel. The degree of mixing is then calculated as a function of bulk volume fraction, predicting the volume fraction that results in the maximum degree of segregation. In bidispersed suspension flow, it is shown that mixing of the larger species is enhanced in straight and staggered herringbone channels while segregation is enhanced at moderate volume fractions in herringbone channels. This suggests mixing and separations can be tailored by adjusting both the suspension properties and the channel geometry.

Psychological intervention (ConquerFear) for treating fear of cancer recurrence: mediators and moderators of treatment efficacy.

PURPOSE: ConquerFear is an efficacious intervention for fear of cancer recurrence (FCR) that demonstrated greater improvements than an attention control (relaxation training) in a randomized controlled trial. This study aimed to determine mediators and moderators of the relative treatment efficacy of ConquerFear versus relaxation. METHODS: One hundred and fifty-two cancer survivors completed 5 therapy sessions and outcome measures before and after intervention and at 6 months' follow-up. We examined theoretically relevant variables as potential mediators and moderators of treatment outcome. We hypothesized that metacognitions and intrusions would moderate and mediate the relationship between treatment group and FCR level at follow-up. RESULTS: Only total FCR score at baseline moderated treatment outcome. Participants with higher levels of FCR benefited more from ConquerFear relative to relaxation on the primary outcome. Changes in metacognitions and intrusive thoughts about cancer during treatment partially mediated the relationship between treatment group and FCR. CONCLUSIONS: These results show that ConquerFear is relatively more effective than relaxation for those with overall higher levels of FCR. The mediation analyses confirmed that the most likely mechanism of treatment efficacy was the reduction in unhelpful metacognitions and intrusive thoughts during treatment, consistent with the theoretical framework underpinning ConquerFear. IMPLICATIONS FOR CANCER SURVIVORS: ConquerFear is a brief, effective treatment for FCR in cancer survivors with early-stage disease. The treatment works by reducing intrusive thoughts about cancer and changing beliefs about worry and is particularly helpful for people with moderate to severe FCR.

Aggressive monopolization of mobile carers by young of a cooperative breeder.

Competition between young of the same brood or litter is of particular interest in the fields of behavioural and evolutionary ecology, because the competing individuals are likely to be closely related, where evolutionary theory predicts a greater degree of cooperation. Studies of cooperative breeding species typically concentrate on who contributes care to rearing young, and assume a passive role of the young. Relatively, little attention has been devoted to considering how intralitter competition between young affects the distribution of care in cooperative breeders. In banded mongoose (Mungos mungo) groups, the majority of pups each form a stable exclusive one-to-one association with an adult group member (its 'escort') that is its principal care provider. This paper presents experimental evidence that each pup aggressively defends access to its escort, preventing other pups approaching, and therefore monopolizes the care provided by its escort. Each pup travels with the group and follows its escort, around which its exclusion zone is fixed: a form of mobile territoriality. This represents a novel system of care of young in a mammal species, but has general implications for the study of the distribution of care of young, particularly in cooperative breeding species. Parents and helpers may provide biased care to young, not due to preference but due to the competitive actions of the young within the brood or litter.

Dog bites: still a problem?

OBJECTIVE: To estimate the incidence of dog bites in the USA and compare it with similar estimates from 1994. DESIGN: Nationally representative cross-sectional, list-assisted, random-digit-dialed telephone survey conducted during 2001-2003. METHODS: Weighted estimates were generated from data collected by surveying 9684 households during 2001-2003 and compared with results from a similar survey conducted in 1994. Estimates for persons aged 15-17 years were extrapolated on the basis of rates for 10-14-year-olds. RESULTS: Whereas the incidence of dog bites among adults remained relatively unchanged, there was a significant (47%) decline in the incidence of dog bites among children compared with that observed in the 1994 survey, particularly among boys and among those aged 0-4 years. Between 2001 and 2003, an estimated 4 521 300 persons were bitten each year. Of these, 885 000 required medical attention (19%). Children were more likely than adults to receive medical attention for a dog bite. Among adults, bite rates decreased with increasing age. Among children and adults, having a dog in the household was associated with a significantly increased incidence of dog bites, with increasing incidence also related to increasing numbers of dogs. CONCLUSIONS: Dog bites continue to be a public health problem affecting 1.5% of the US population annually. Although comparison with similar data from 1994 suggests that bite rates for children are decreasing, there still appears to be a need for effective prevention programs.

Shear-induced particle migration in one-, two-, and three-dimensional flows.

We investigate the segregation resulting from the competition between advection and shear-induced migration of suspensions in steady open flows. Herringbone channels form a concentration profile deviating from the particle focusing found in straight channels. Transients can result from a buckling instability during the onset of migration when particle-depleted fluid is injected into particle-rich fluid. In chaotic flows, the better mixing found at low bulk volume fraction is not seen at higher bulk volume fraction. Thus, the ability of static mixers to reduce the effects of shear-induced migration is significantly limited.

Debriefing after failed paediatric resuscitation: a survey of current UK practice.

OBJECTIVES: Debriefing is a form of psychological "first aid" with origins in the military. It moved into the spotlight in 1983, when Mitchell described the technique of critical incident stress debriefing. To date little work has been carried out relating to the effectiveness of debriefing hospital staff after critical incidents. The aim of this study was to survey current UK practice in order to develop some "best practice" guidelines. METHODS: This study was a descriptive evaluation based on a structured questionnaire survey of 180 lead paediatric and emergency medicine consultants and nurses, selected from 50 UK trusts. Questions collected data about trust policy and events and also about individuals' personal experience of debrief. Free text comments were analyzed using the framework method described for qualitative data. RESULTS: Overall, the response rate was 80%. 62% said a debrief would occur most of the time. 85% reported that the main aim was to resolve both medical and psychological and emotional issues. Nearly all involve both doctors and nurses (88%); in over half (62%) other healthcare workers would be invited, eg, paramedics, students. Sessions are usually led by someone who was involved in the resuscitation attempt (76%). This was a doctor in 80%, but only 18% of responders said that a specifically trained person had led the session. Individuals' psychological issues would be discussed further on a one-to-one basis and the person directed to appropriate agencies. Any strategic working problems highlighted would be discussed with a senior member of staff and resolved via clinical governance pathways. CONCLUSIONS: Little is currently known about the benefits of debriefing hospital staff after critical incidents such as failed resuscitation. Debriefing is, however, widely practised and the results of this study have been used to formulate some best practice guidelines while awaiting evidence from further studies.

Applying Data Preprocessing Methods to Predict Premature Birth.

Data mining and pattern classification tools have{enabled prediction of several medical outcomes with high levels of accuracy. This is due to the capability of handling large datasets, even those with missing values. Preterm birth (PTB) can have damaging long-term effects for infants and rates have been increasing over the last two decades worldwide. The purpose of this work was to investigate whether preprocessing methods, when applied to two different prenatal datasets, can improve prediction accuracy of our software tool to predict PTB. The primary software used within this work was R. The software was used to deal with missing values and class imbalances found in these two datasets. The results show that in comparison to our past work, we have managed to increase the performance of the prediction tool using the metrics of sensitivity, specificity, and ROC values.

A two centre observational study of simultaneous pulse oximetry and arterial oxygen saturation recordings in intensive care unit patients.

The influence of variables that might affect the accuracy of pulse oximetry (SpO2) recordings in critically ill patients is not well established. We sought to describe the relationship between paired SpO2/SaO2 (oxygen saturation via arterial blood gas analysis) in adult intensive care unit (ICU) patients and to describe the diagnostic performance of SpO2 in detecting low SaO2 and PaO2. A paired SpO2/SaO2 measurement was obtained from 404 adults in ICU. Measurements were used to calculate bias, precision, and limits of agreement. Associations between bias and variables including vasopressor and inotrope use, capillary refill time, hand temperature, pulse pressure, body temperature, oximeter model, and skin colour were estimated. There was no overall statistically significant bias in paired SpO2/SaO2 measurements; observed limits of agreement were +/-4.4%. However, body temperature, oximeter model, and skin colour, were statistically significantly associated with the degree of bias. SpO2 <89% had a sensitivity of 3/7 (42.9%; 95% confidence intervals, CI, 9.9% to 81.6%) and a specificity of 344/384 (89.6%; 95% CI 86.1% to 92.5%) for detecting SaO2 <89%. The absence of statistically significant bias in paired SpO2/SaO2 in adult ICU patients provides support for the use of pulse oximetry to titrate oxygen therapy. However, SpO2 recordings alone should be used cautiously when SaO2 recordings of 4.4% higher or lower than the observed SpO2 would be of concern. A range of variables relevant to the critically ill had little or no effect on bias.

Non-fatal horse related injuries treated in emergency departments in the United States, 2001-2003.

OBJECTIVE: To characterise and provide nationally representative estimates of persons with non-fatal horse related injuries treated in American emergency departments. METHODS: The National Electronic Injury Surveillance System All Injury Program (NEISS-AIP) is a stratified probability sample comprising 66 hospitals. Data on injuries treated in these emergency departments are collected and reported. NEISS-AIP data on all types (horseback riding and otherwise) of non-fatal horse related injuries from 2001 to 2003 were analysed. RESULTS: An estimated 102,904 persons with non-fatal horse related injuries (35.7 per 100,000 population) were treated in American emergency departments each year from 2001 to 2003 inclusive. Non-fatal injury rates were higher for females (41.5 per 100,000) than for males (29.8 per 100,000). Most patients were injured while mounted on a horse (66.1%), commonly from falling or being thrown by the horse; while not mounted, injuries most often resulted from being kicked by the horse. The body parts most often injured were the head/neck region (23.2%), lower extremity (22.2%), and upper extremity (21.5%). The most common principal diagnoses were contusions/abrasions (31.4%) and fractures (25.2%). For each year that was studied, an estimated 11 502 people sustained traumatic brain injuries from horse related incidents. Overall, more than 11% of those injured were admitted to hospital. CONCLUSIONS: Horse related injuries are a public health concern not just for riders but for anyone in close contact with horses. Prevention programmes should target horseback riders and horse caregivers to promote helmet use and educate participants about horse behaviour, proper handling of horses, and safe riding practices.

Things that go beep: experience with an ED guideline for use of a handheld metal detector in the management of ingested non-hazardous metallic foreign bodies.

OBJECTIVES: To review compliance with our emergency department (ED) guideline on the imaging of ingested non-hazardous metallic foreign bodies in children, investigate adverse outcomes, and make suggestions for improving the guideline. METHODS: Retrospective analysis of patients presenting in a 3 year period to a paediatric ED with a history of possible metallic foreign body (MFB) ingestion, who were managed according to an ED guideline. RESULTS: We identified 430 episodes of possible MFB ingestion, of which 422 were eligible for inclusion in the study. Compliance with the guideline was 77.8% with no significant adverse events. The exclusion of symptoms as a criterion for x ray results in a reduction in the x ray rate of 56% in the symptomatic group with no increase in adverse events. CONCLUSION: A handheld metal detector (HMD) can be safely and reliably used in lieu of plain radiography to investigate children with a history of MFB ingestion, irrespective of symptoms and without incurring any significant adverse events.

Chemotherapy in neuroendocrine/Merkel cell carcinoma of the skin: case series and review of 204 cases.

PURPOSE: To study the use of chemotherapy for Merkel cell carcinoma (MCC) of the skin. PATIENTS AND METHODS: Twenty-five cases of MCC were treated at the London Regional Cancer Center between 1987 and 1997. Thirteen cases treated with chemotherapy were reviewed with 191 cases from the literature. RESULTS: At presentation, 24 patients had localized skin lesions (stage I) and one had locoregional involvement (stage II). Among the nine cases with recurrent nodal disease, six had chemotherapy as a component of salvage treatment. They were all free of disease at a median of 19 months (range, 12 to 37 months). In contrast, two patients who had salvage radiotherapy alone died of disease. Overall survival (OS) and disease-free survival (DFS) were 59% and 43%, respectively, at two years. Median OS and DFS were 29 months (range, 1 to 133 months) and 9 months (range, 1 to 133 months), respectively. Nodal disease developed in 12 (50%) of 24 patients with stage I disease, and distant metastases developed in six (25%) of 24. Including those from the literature, there were 204 cases treated with chemotherapy. Cyclophosphamide/doxorubicin (or epirubicin)/vincristine combination +/- prednisone was the most commonly used chemotherapy regimen (47 cases), with an overall response rate of 75.7% (35.1% complete, 35. 1% partial, and 5.4% minor responses). Etoposide/cisplatin (or carboplatin) was the next most commonly used regimen (27 cases), with an overall response rate of 60% (36% complete and 24% partial responses). The difference in response rate was not statistically significant (P =.19). Among the 204 cases, there were seven (3.4%) toxic deaths. CONCLUSION: Chemoradiation for locally recurrent or advanced disease may be an option for patients with a good performance status.

Cardiomyopathy of limb-girdle muscular dystrophy.

OBJECTIVES: This study sought to find an association between dilated cardiomyopathy and limb-girdle muscular dystrophy. BACKGROUND: Cardiomyopathy has been seen in various neuromuscular disorders, but it has not been recognized to be associated with limb-girdle muscular dystrophy. METHODS: We investigated three sisters with well documented limb-girdle dystrophy and congestive heart failure by the 3rd decade of life. All underwent noninvasive evaluation of left ventricular systolic function by both echocardiography and radionuclide scanning, and one also had cardiac catheterization. Deoxyribonucleic acid (DNA) linkage analysis was performed in these affected subjects and in the unaffected family members, and DNA was extracted from mononuclear cells with primer sequences for three chromosome 13q microsatellite markers. RESULTS: The parents had no evidence of clinical disease, but all three sisters had echocardiographic evidence of dilated cardiomyopathy. The sister with additional evidence of left ventricular dysfunction of cardiac catheterization had no coronary artery disease. The affected subjects had the same paternal allele for three potential markers of limb-girdle muscular dystrophy but different maternal alleles. The very small family size did not permit statistical confirmation or refutation of linkage for chromosome 13q markers. CONCLUSIONS: Demonstrable cardiomyopathy accompanying limb-girdle muscular dystrophy and its probable genetic associations require continued investigation by anticipating the cardiomyopathy in limb-girdle muscular dystrophy.

Exercise-related injuries among women: strategies for prevention from civilian and military studies.

SCOPE OF THE PROBLEM: The numerous health benefits of physical activity have been well documented, resulting in public health support of regular physical activity and exercise. Although beneficial, exercise also has corresponding risks, including musculoskeletal injuries. The incidence and risk factors for exercise-related injury have been poorly assessed in women. Many civilian exercise activities (e.g., jogging, walking, and erobics) have corollaries in military physical training; injury incidence and risk factors associated with military physical training have been more thoroughly studied. ETIOLOGIC FACTORS: Injury risks increase as the amount of training increases (increased xposure). The same exercise parameters that can be modified to enhance physical fitness (i.e., frequency, duration, and intensity) also influence the risk for injury in a dose-response manner. Higher levels of current physical fitness (aerobic fitness) protect the participant against future injury. A history of previous injury is a risk factor for future injury. Smoking cigarettes has been associated with increased risk for exercise-related injury. Studies conducted in military populations suggest that the most important risk factor for injuries among persons engaged in vigorous weight-bearing aerobic physical activity might be low aerobic fitness rather than female sex. RECOMMENDATIONS FOR PREVENTION: Because of the limited scientific research regarding women engaging in exercise, general recommendations are provided. Women starting exercise programs should be realistic about their goals and start slowly at frequency, duration, and intensity levels commensurate with their current physical fitness condition. Women should be informed about the early indicators of potential injury. Women who have sustained an injury should take precautions to prevent reinjury (e.g., ensuring appropriate recovery and rehabilitation). RESEARCH AGENDA: In general, a combination of factors affects the risk for exercise-related injury in women. How these factors act singly and in combination to influence injury risk is not well understood. Additional research regarding exercise-related injury in women is needed to answer many of the remaining epidemiologic questions and to help develop exercise programs that improve health while reducing the risk for injury. CONCLUSION: Exercise is an important component in improving and maintaining health; however, injury is also an accompanying risk. A review of key military and civilian research studies regarding exercise-related injuries provides some clues to reducing these injuries in women. Greater adherence to exercise guidelines can help decrease these risks.

Nucleoplasmic Ca(2+)loading is regulated by mobilization of perinuclear Ca(2+).

Regulation of nucleoplasmic calcium (Ca(2+)) concentration may occur by the mobilization of perinuclear luminal Ca(2+)pools involving specific Ca(2+)pumps and channels of both inner and outer perinuclear membranes. To determine the role of perinuclear luminal Ca(2+), we examined freshly cultured 10 day-old embryonic chick ventricular cardiomyocytes. We obtained evidence suggesting the existence of the molecular machinery required for the bi-directional Ca(2+)fluxes using confocal imaging techniques. Embryonic cardiomyocytes were probed with antibodies specific for ryanodine-sensitive Ca(2+)channels (RyR2), sarco/endoplasmic reticulum Ca(2+)ATPase (SERCA2)-pumps, and fluorescent BODIPY derivatives of ryanodine and thapsigargin. Using immunocytochemistry techniques, confocal imaging showed the presence of RyR2 Ca(2+)channels and SERCA2-pumps highly localized to regions surrounding the nucleus, referable to the nuclear envelope. Results obtained from Fluo-3, AM loaded ionomycin-perforated embryonic cardiomyocytes demonstrated that gradual increases of extranuclear Ca(2+)from 100 to 1600 nM Ca(2+)was localized to the nucleus. SERCA2-pump inhibitors thapsigargin and cyclopiazonic acid showed a concentration-dependent inhibition of nuclear Ca(2+)loading. Furthermore, ryanodine demonstrated a biphasic concentration-dependence upon active nuclear Ca(2+)loading. The concomitant addition of thapsigargin or cyclopiazonic acid with ryanodine at inhibitory concentrations caused an significant increase in nuclear Ca(2+)loading at low concentrations of extranuclear added Ca(2+). Our results show that the perinuclear lumen in embryonic chick ventricular cardiomyocytes is capable of autonomously regulating nucleoplasmic Ca(2+)fluxes.