The effects of demographic, psychosocial, and socioeconomic characteristics on access to heart transplantation and left ventricular assist device.

Background: This study aims to better understand how demographic, psychosocial, and socioeconomic factors influence the selection of patients for advanced therapies for heart failure (heart transplant and left ventricular assist device (LVAD)). Methods: Patients evaluated for heart transplant or LVAD at a large, Midwestern hospital system were assessed retrospectively. Three outcomes were analyzed: 1) Patients who were evaluated and approved to receive a transplant or LVAD were compared to patients who were not approved for transplant or LVAD; 2) Patients who were listed for transplant were compared to patients not listed; and 3) Patients who received a transplant or LVAD were compared to patients who did not receive a transplant or LVAD. ANOVA was used for continuous variables and Chi-squared test for categorical variables. Significant variables were further analyzed by logistic regression. Results: Four hundred fifty-nine patients were included. Marital status (p = 0.004), race (p = 0.008), social support (p < 0.001), mental health (p = 0.006), and substance use (p < 0.001) were associated with whether patients were approved for transplant or LVAD. Patients with public insurance were half as likely (OR 0.495) to be listed for transplant once approved. Conclusions: Financial, psychosocial, and demographic characteristics all play a role in selection for advanced therapies for heart failure. These insights can help guide future work on interventions to address the social disparities in access to heart transplant and LVAD.

The Impact of a Home-Based Computerized Cognitive Training Intervention on Fall Risk Measure Performance in Community Dwelling Older Adults, a Pilot Study.

OBJECTIVES: Cognitive intervention studies have reported improvements in various domains of cognition as well as a transfer effect of improved function post training. Despite the availability of web based cognitive training programs, most intervention studies have been performed under the supervision of researchers. Therefore, the purpose of this study was to first, examine the feasibility of a six week home based computerized cognitive training (CCT) program in a group of community dwelling older adults and, second, to determine if a CCT program which focused on set shifting, attention, and visual spatial ability impacted fall risk measure performance. DESIGN: This pilot study used a pretest/posttest experimental design with randomization by testing site to an intervention or control group. PARTICIPANTS: Community dwelling older adults (mean age = 74.6 years) participated in either the control (N=25) or the intervention group (N=19). INTERVENTION: Intervention group subjects participated in 6 weeks of home based CCT 3x/week for an average of 23 minutes/session, using an online CCT program. MEASUREMENTS: Comparisons of mean scores on three measures of physical function (usual gait speed, five times sit to stand, timed up and go) were completed at baseline and week 7. RESULTS: Following the completion of an average of 18 sessions of CCT at home with good adherence (86%) and retention (92%) rates, a statistically significant difference in gait speed was found between groups with an average improvement of 0.14 m/s in the intervention group. CONCLUSION: A home based CCT program is a feasible approach to targeting cognitive impairments known to influence fall risk and changes in gait in older adults.

Beclin 1 regulates growth factor receptor signaling in breast cancer.

Beclin 1 is a haploinsufficient tumor suppressor that is decreased in many human tumors. The function of beclin 1 in cancer has been attributed primarily to its role in the degradative process of macroautophagy. However, beclin 1 is a core component of the vacuolar protein sorting 34 (Vps34)/class III phosphatidylinositoI-3 kinase (PI3KC3) and Vps15/p150 complex that regulates multiple membrane-trafficking events. In the current study, we describe an alternative mechanism of action for beclin 1 in breast cancer involving its control of growth factor receptor signaling. We identify a specific stage of early endosome maturation that is regulated by beclin 1, the transition of APPL1-containing phosphatidyIinositol 3-phosphate-negative (PI3P(-)) endosomes to PI3P(+) endosomes. Beclin 1 regulates PI3P production in response to growth factor stimulation to control the residency time of growth factor receptors in the PI3P(-)/APPL(+)-signaling-competent compartment. As a result, suppression of BECN1 sustains growth factor-stimulated AKT and ERK activation resulting in increased breast carcinoma cell invasion. In human breast tumors, beclin 1 expression is inversely correlated with AKT and ERK phosphorylation. Our data identify a novel role for beclin 1 in regulating growth factor signaling and reveal a mechanism by which loss of beclin 1 expression would enhance breast cancer progression.

Initial experiences with isolated limb perfusion for unresectable melanoma of the limb.

AIMS: Our initial results with isolated limb perfusion (ILP) using melphalan ± TNF alpha in patients with unresectable melanoma of the limb were analyzed. METHODS: 15 ILPs were performed between 2001 and 2006. Indications for ILP were stage III or IV metastatic melanoma. Complete and partial response rates, time to local and systemic tumour progression rates, disease free and overall survival rates were retrospectively analyzed. RESULTS: Overall response rate was 93%, with a 67% complete response and a 26% partial response rate. In eight cases grade II, while in six cases grade III local toxicity was detected. However, one mortality was detected in the early postoperative phase due to a grade V complication. With a mean follow-up period of 2.7 years, eight patients had local progression and in four of those, systemic progression was detected. CONCLUSIONS: ILP was generally well tolerated and limb salvage was achieved in all cases.

A definitive role for sentinel lymph node mapping with biopsy for cutaneous melanoma of the head and neck.

AIMS: The aim of this study was to evaluate the role, if any, of sentinel lymph node mapping (SLNM) with biopsy (SLNB) in patients with cutaneous melanoma of the head and neck. METHODS: Consecutive patients with cutaneous melanoma of the head and neck regions undergoing SLNM with biopsy were identified from a departmental database comprising 480 patients in total from 2000-2007. Factors examined included demographic data, histological subtype, site and depth of lesion, pre-operative lymphoscintigraphy, percentage of positive SLNs, regional recurrence in the setting of a negative SLNB result (false-negative rate), complications, further lymphadenectomy, percentage of skin grafting required and follow-up. RESULTS: The median patient age was 51 years (range 18-90 years). The mean Breslow depth was 3.25 mm (range 1-19 mm). Five patients presented with stage III/IV disease. A SLN was identified in 27/40 patients who underwent head and neck SLN mapping (mean two lymph nodes per patient). Of these, six (22%) patients were positive for metastatic melanoma. The false-negative rate was 9.5%. The median follow up for patients was 39.6 months (range 12-96 months). No facial nerve injury or other major morbidity occurred. CONCLUSIONS: This study indicates that SLNB is a reliable and safe technique to diagnose regional spread from head and neck cutaneous melanoma. It is more difficult than at other sites. These lesions have a higher incidence of failed SLN mapping and a higher rate of recurrence following negative SLNB, when compared to truncal and extremity lesions. Nodular melanomas are more likely to fail the sentinel lymph node mapping procedure than other histological subtypes.

Sentinel lymph node biopsy: is it possible to reduce false negative rates by excluding patients with nodular melanoma?

OBJECTIVE: The aim of this study was to review the outcome of sentinel lymph node biopsy (SLNB) in patients with melanoma and to delineate whether patients with nodular melanoma are more likely to develop nodal recurrence despite negative SLNB. METHODS: Consecutive patients with cutaneous melanoma undergoing SLNB were identified from a departmental database between 1997 and 2005. Factors including demographic data, site, histological subtype, depth and outcome were examined. RESULTS: Of 131 patients, 103 were node negative and eligible for study. The median age was 53 (16-82) years with 46 patients being male (45%) and 57 female (55%). Primary melanoma sites included lower limb (49; 48%), upper limb (29; 28%), head (12; 11%), trunk (7; 7%) and back (6; 6%). The median Breslow thickness was 2mm. Superficial spreading accounted for 43% of melanoma with nodular accounting for 42%. Median follow-up was 40 (3-90) months. Of 20 relapses, seven recurred in the same nodal basin, three were satellite recurrences, one recurred with both satellite and nodal lesions simultaneously, and nine experienced haematogenous spread. Of the eight patients who developed recurrence in the same nodal basin, four were of nodular histological subtype (p=NS). All of the three patients with satellite lesions had nodular melanoma histologically (p=0.02). When nodal and satellite recurrences were combined, eight of 11 were histologically nodular (p=0.01). CONCLUSIONS: This study indicates that lymphatic recurrence occurs more often in SLNB negative patients with nodular melanoma. Further evaluation of the inclusion criteria for sentinel node biopsy is warranted.

Weight loss in overweight patients maintained on atypical antipsychotic agents.

BACKGROUND: Weight gain and associated medical morbidity offset the reduction of extrapyramidal side effects associated with atypical antipsychotics. Efforts to control weight in antipsychotic-treated patients have yielded limited success. METHODS: We studied the impact of an intensive 24-week program of diet, exercise, and counseling in 17 chronically psychotic patients (10 women, seven men) who entered at high average body weight (105.0+/-18.4 kg) and body mass index (BMI) (36.6+/-4.6 kg/m(2)). A total of 12 subjects who completed the initial 24 weeks elected to participate in an additional 24-week, less intensive extension phase. RESULTS: By 24 weeks, weight-loss/patient averaged 6.0 kg (5.7%) and BMI decreased to 34.5 (by 5.7%). Blood pressure decreased from 130/83 to 116/74 (11% improvement), pulse fell slightly, and serum cholesterol and triglyceride concentrations changed nonsignificantly. With less intensive management for another 24 weeks, subjects regained minimal weight (0.43 kg). CONCLUSIONS: These findings add to the emerging view that weight gain is a major health problem associated with modern antipsychotic drugs and that labor-intensive weight-control efforts in patients requiring antipsychotic treatment yield clinically promising benefits. Improved treatments without weight-gain risk are needed.

The fleet feet of haematopoietic stem cells: rapid motility, interaction and proteopodia.

Haematopoietic stem cells (HSCs) have been extensively characterized regarding in vivo engraftment, surface epitopes and genetic regulation. However, little is known about the homing of these rare cells, and their intrinsic motility and membrane deformation capacity. We used high-speed optical-sectioning microscopy and inverted fluorescent videomicroscopy to study highly purified murine lineage-negative, rhodamine-low, Hoechst-low HSCs over time under various in vitro conditions. We discovered extremely rapid motility, directed migration to stromal cells and marked membrane modulation. High resolution images with three-dimensional reconstruction showed the general presence of microspikes. Further, pseudopodia (proteopodia) were observed that were induced by stromal-derived factor-1 and steel factor. Proteopodia were directed towards and were quenched by stromal cells, at times bridged HSCs, and could rapidly retract or detach from cells. Proteopodia were also observed in vivo with homed HSCs in frozen sections of murine spleen, lung and heart. This is the first demonstration that HSCs are both fast and highly malleable in phenotype.

Recombinant aequorin and green fluorescent protein as valuable tools in the study of cell signalling.

Luminous proteins include primary light producers, such as aequorin, and secondary photoproteins that in some organisms red-shift light emission for better penetration in space. When expressed in heterologous systems, both types of proteins may act as versatile reporters capable of monitoring phenomena as diverse as calcium homoeostasis, protein sorting, gene expression, and so on. The Ca(2+)-sensitive photoprotein aequorin was targeted to defined intracellular locations (organelles, such as mitochondria, endoplasmic reticulum, sarcoplasmic reticulum, Golgi apparatus and nucleus, and cytoplasmic regions, such as the bulk cytosol and the subplasmalemmal rim), and was used to analyse Ca(2+) homoeostasis at the subcellular level. We will discuss this application, reviewing its advantages and disadvantages and the experimental procedure. The applications of green fluorescent protein (GFP) are even broader. Indeed, the ability to molecularly engineer and recombinantly express a strongly fluorescent probe has provided a powerful tool for investigating a wide variety of biological events in live cells (e.g. tracking of endogenous proteins, labelling of intracellular structures, analysing promoter activity etc.). More recently, the demonstration that, using appropriate mutants and/or fusion proteins, GFP fluorescence can become sensitive to physiological parameters or activities (ion concentration, protease activity, etc.) has further expanded its applications and made GFP the favourite probe of cell biologists. We will here present two applications in the field of cell signalling, i.e. the use of GFP chimaeras for studying the recruitment of protein kinase C isoforms and the activity of intracellular proteases.

Relationship of Ca2+ sparks to STOCs studied with 2D and 3D imaging in feline oesophageal smooth muscle cells.

We recorded Ca2+ sparks and spontaneous transient outward currents (STOCs) simultaneously in smooth muscle cells using whole-cell patch recording and a unique, high-speed widefield digital imaging system to monitor fluo-3 fluorescence in both two and three dimensions (2D and 3D). In 2D imaging, the correlation between the amplitude of a spark and its corresponding STOC was a weak one, and 27 % of the sparks failed to cause STOCs. The STOCless sparks were not significantly different in amplitude from those that caused STOCs. Three-dimensional imaging disclosed that STOCless sparks were located close to the cell surface, and on average their apparent distance from the cell surface was not significantly different from the sparks that cause STOCs. Statistical evaluation of spark clusters disclosed that there were regions of the cell where the probability of spark occurrence was high and others where it was quite low.

Insulin action on GLUT4 traffic visualized in single 3T3-l1 adipocytes by using ultra-fast microscopy.

A novel imaging technology, high-speed microscopy, has been used to visualize the process of GLUT4 translocation in response to insulin in single 3T3-L1 adipocytes. A key advantage of this technology is that it requires extremely low light exposure times, allowing the quasi-continuous capture of information over 20-30 min without photobleaching or photodamage. The half-time for the accumulation of GLUT4-eGFP (enhanced green fluorescent protein) at the plasma membrane in a single cell was found to be of 5-7 min at 37 degrees C. This half-time is substantially longer than that of exocytic vesicle fusion in neuroendocrine cells, suggesting that additional regulatory mechanisms are involved in the stimulation of GLUT4 translocation by insulin. Analysis of four-dimensional images (3-D over time) revealed that, in response to insulin, GLUT4-eGFP-enriched vesicles rapidly travel from the juxtanuclear region to the plasma membrane. In nontransfected adipocytes, impairment of microtubule and actin filament function inhibited insulin-stimulated glucose transport by 70 and 50%, respectively. When both filament systems were impaired insulin-stimulated glucose transport was completely inhibited. Taken together, the data suggest that the regulation of long-range motility of GLUT4-containing vesicles through the interaction with microtubule- and actin-based cytoskeletal networks plays an important role in the overall effect of insulin on GLUT4 translocation.

Prospective evaluation of antiemetic outcome following high-dose chemotherapy with hematopoietic stem cell support.

Considerable progress has been made in improving the control of chemotherapy-induced emesis. The impact of available antiemetic options for patients receiving stem cell transplants is unclear, as few prospective data have been collected. We prospectively evaluated antiemetic outcome in patients receiving stem cell transplantation over a 7-day period following the initiation of chemotherapy. The primary endpoints were the number of emetic episodes and the extent of nausea measured on a four-point scale. Eighty-two patients were evaluated. Ninety-five percent of patients had nausea during the first week of treatment; 80% had at least one emetic episode. The percentage of patients with emesis was as follows: day 1: 13%, day 2: 21%, day 3: 30%, day 4: 38%, day 5: 44%, day 6: 39%, day 7: 18%. In multivariate analysis, gender, emesis with prior chemotherapy, history of morning or motion sickness, type of transplant (auto vs allo), use of total body irradiation, or use of dexamethasone did not effect emesis control. Most patients receiving high-dose chemotherapy experience incompletely controlled emesis. Control of nausea and emesis progressively worsened with each subsequent day following initiation of chemotherapy, reaching a nadir on day 5. New treatment approaches are needed to improve emesis control in this patient population.

Dynamics of signaling between Ca(2+) sparks and Ca(2+)- activated K(+) channels studied with a novel image-based method for direct intracellular measurement of ryanodine receptor Ca(2+) current.

Ca(2+) sparks are highly localized cytosolic Ca(2+) transients caused by a release of Ca(2+) from the sarcoplasmic reticulum via ryanodine receptors (RyRs); they are the elementary events underlying global changes in Ca(2+) in skeletal and cardiac muscle. In smooth muscle and some neurons, Ca(2+) sparks activate large conductance Ca(2+)-activated K(+) channels (BK channels) in the spark microdomain, causing spontaneous transient outward currents (STOCs) that regulate membrane potential and, hence, voltage-gated channels. Using the fluorescent Ca(2+) indicator fluo-3 and a high speed widefield digital imaging system, it was possible to capture the total increase in fluorescence (i.e., the signal mass) during a spark in smooth muscle cells, which is the first time such a direct approach has been used in any system. The signal mass is proportional to the total quantity of Ca(2+) released into the cytosol, and its rate of rise is proportional to the Ca(2+) current flowing through the RyRs during a spark (I(Ca(spark))). Thus, Ca(2+) currents through RyRs can be monitored inside the cell under physiological conditions. Since the magnitude of I(Ca(spark)) in different sparks varies more than fivefold, Ca(2+) sparks appear to be caused by the concerted opening of a number of RyRs. Sparks with the same underlying Ca(2+) current cause STOCs, whose amplitudes vary more than threefold, a finding that is best explained by variability in coupling ratio (i.e., the ratio of RyRs to BK channels in the spark microdomain). The time course of STOC decay is approximated by a single exponential that is independent of the magnitude of signal mass and has a time constant close to the value of the mean open time of the BK channels, suggesting that STOC decay reflects BK channel kinetics, rather than the time course of [Ca(2+)] decline at the membrane. Computer simulations were carried out to determine the spatiotemporal distribution of the Ca(2+) concentration resulting from the measured range of I(Ca(spark)). At the onset of a spark, the Ca(2+) concentration within 200 nm of the release site reaches a plateau or exceeds the [Ca(2+)](EC50) for the BK channels rapidly in comparison to the rate of rise of STOCs. These findings suggest a model in which the BK channels lie close to the release site and are exposed to a saturating [Ca(2+)] with the rise and fall of the STOCs determined by BK channel kinetics. The mechanism of signaling between RyRs and BK channels may provide a model for Ca(2+) action on a variety of molecular targets within cellular microdomains.

Mechanisms underlying InsP3-evoked global Ca2+ signals in mouse pancreatic acinar cells.

In secretory epithelial cells, complex patterns of Ca2+ signals regulate physiological processes. How these patterns are generated is still not fully understood. In particular, the basis of global Ca2+ waves is not clear. We have studied regional differences in InsP3-evoked Ca2+ release in single mouse pancreatic acinar cells, using high-speed (approximately 90 frames s-1), high-sensitivity Ca2+ imaging combined with rapid (10 ms) spot photolysis (2 micrometer diameter) of caged InsP3. Within a single region we measured Ca2+ response latency and rate of rise to construct an InsP3 dose-response relationship. Spot InsP3 liberation in the secretory pole region consistently elicited a dose-dependent, rapid release of Ca2+. Spot InsP3 liberation in the basal pole region of approximately 50% of cells elicited a similar dose-response relationship but with a lower apparent InsP3 affinity than in the secretory pole. In the other cells, basal pole InsP3 liberation did not elicit active Ca2+ release, even at the highest stimulus intensities we employed, although these same cells did respond when the stimulus spot was moved to different regions. We conclude that in the basal pole active sites of rapid Ca2+ release have a lower functional affinity for InsP3 than those in the secretory pole and are spread out in discrete sites across the basal pole. These properties explain the propagation of Ca2+ waves across the basal pole that are only observed at higher stimulus levels.

Microtubules regulate local Ca2+ spiking in secretory epithelial cells.

The role of the cytoskeleton in regulating Ca(2+) release has been explored in epithelial cells. Trains of local Ca(2+) spikes were elicited in pancreatic acinar cells by infusion of inositol trisphosphate through a whole cell patch pipette, and the Ca(2+)-dependent Cl(-) current spikes were recorded. The spikes were only transiently inhibited by cytochalasin B, an agent that acts on microfilaments. In contrast, nocodazole (5-100 micrometer), an agent that disrupts the microtubular network, dose-dependently reduced spike frequency and decreased spike amplitude leading to total blockade of the response. Consistent with an effect of microtubular disruption, colchicine also inhibited spiking but neither Me(2)SO nor beta-lumicolchicine, an inactive analogue of colchicine, had any effect. The microtubule-stabilizing agent, taxol, also inhibited spiking. The nocodazole effects were not due to complete loss of function of the Ca(2+) signaling apparatus, because supramaximal carbachol concentrations were still able to mobilize a Ca(2+) response. Finally, as visualized by 2-photon excitation microscopy of ER-Tracker, nocodazole promoted a loss of the endoplasmic reticulum in the secretory pole region. We conclude that microtubules specifically maintain localized Ca(2+) spikes at least in part because of the local positioning of the endoplasmic reticulum.

Intercellular calcium waves in HeLa cells expressing GFP-labeled connexin 43, 32, or 26.

This study was undertaken to obtain direct evidence for the involvement of gap junctions in the propagation of intercellular Ca(2+) waves. Gap junction-deficient HeLa cells were transfected with plasmids encoding for green fluorescent protein (GFP) fused to the cytoplasmic carboxyl termini of connexin 43 (Cx43), 32 (Cx32), or 26 (Cx26). The subsequently expressed GFP-labeled gap junctions rendered the cells dye- and electrically coupled and were detected at the plasma membranes at points of contact between adjacent cells. To correlate the distribution of gap junctions with the changes in [Ca(2+)](i) associated with Ca(2+) waves and the distribution of the endoplasmic reticulum (ER), cells were loaded with fluorescent Ca(2+)-sensitive (fluo-3 and fura-2) and ER membrane (ER-Tracker) dyes. Digital high-speed microscopy was used to collect a series of image slices from which the three-dimensional distribution of the gap junctions and ER were reconstructed. Subsequently, intercellular Ca(2+) waves were induced in these cells by mechanical stimulation with or without extracellular apyrase, an ATP-degrading enzyme. In untransfected HeLa cells and in the absence of apyrase, cell-to-cell propagating [Ca(2+)](i) changes were characterized by initiating Ca(2+) puffs associated with the perinuclear ER. By contrast, in Cx-GFP-transfected cells and in the presence of apyrase, [Ca(2+)](i) changes were propagated without initiating perinuclear Ca(2+) puffs and were communicated between cells at the sites of the Cx-GFP gap junctions. The efficiency of Cx expression determined the extent of Ca(2+) wave propagation. These results demonstrate that intercellular Ca(2+) waves may be propagated simultaneously via an extracellular pathway and an intracellular pathway through gap junctions and that one form of communication may mask the other.

A bimodal pattern of InsP(3)-evoked elementary Ca(2+) signals in pancreatic acinar cells.

InsP(3)-evoked elementary Ca(2+) release events have been postulated to play a role in providing the building blocks of larger Ca(2+) signals. In pancreatic acinar cells, low concentrations of acetylcholine or the injection of low concentrations of InsP(3) elicit a train of spatially localized Ca(2+) spikes. In this study we have quantified these responses and compared the Ca(2+) signals to the elementary events shown in Xenopus oocytes. The results demonstrate, at the same concentrations of InsP(3), Ca(2+) signals consisting of one population of small transient Ca(2+) release events and a second distinct population of larger Ca(2+) spikes. The signal mass amplitudes of both types of events are within the range of amplitudes for the elementary events in Xenopus oocytes. However, the bimodal Ca(2+) distribution of Ca(2+) responses we observe is not consistent with the continuum of event sizes seen in Xenopus. We conclude that the two types of InsP(3)-dependent events in acinar cells are both elementary Ca(2+) signals, which are independent of one another. Our data indicate a complexity to the organization of the Ca(2+) release apparatus in acinar cells, which might result from the presence of multiple InsP(3) receptor isoforms, and is likely to be important in the physiology of these cells.

Multiple pathways responsible for the stretch-induced increase in Ca2+ concentration in toad stomach smooth muscle cells.

1. A digital imaging microscope with fura-2 as the Ca2+ indicator was used to determine the sources for the rise in intracellular calcium concentration ([Ca2+]i) that occurs when the membrane in a cell-attached patch is stretched. Unitary ionic currents from stretch-activated channels and [Ca2+]i images were recorded simultaneously. 2. When suction was applied to the patch pipette to stretch a patch of membrane, Ca2+-permeable cation channels (stretch-activated channels) opened and a global increase in [Ca2+]i occurred, as well as a greater focal increase in the vicinity of the patch pipette. The global changes in [Ca2+]i occurred only when stretch-activated currents were sufficient to cause membrane depolarization, as indicated by the reduction in amplitude of the unitary currents. 3. When Ca2+ was present only in the pipette solution, just the focal change in [Ca2+]i was obtained. This focal change was not seen when the contribution from Ca2+ stores was eliminated using caffeine and ryanodine. 4. These results suggest that the opening of stretch-activated channels allows ions, including Ca2+, to enter the cell. The entry of positive charge triggers the influx of Ca2+ into the cell by causing membrane depolarization, which presumably activates voltage-gated Ca2+ channels. The entry of Ca2+ through stretch-activated channels is also amplified by Ca2+ release from internal stores. This amplification appears to be greater than that obtained by activation of whole-cell Ca2+ currents. These multiple pathways whereby membrane stretch causes a rise in [Ca2+]i may play a role in stretch-induced contraction, which is a characteristic of many smooth muscle tissues.

Long-term outcomes of stereotactic breast biopsies.

Stereotactic core needle biopsies (SCNBs) are accurate and relatively convenient for the patient; however, the long-term follow-up of benign results has not been reported. All patients between 1993 and 1998 undergoing SCNB at a community-based hospital were entered into a registry. Follow-up was obtained by a retrospective analysis of the charts. Biopsies were performed on 865 lesions. One hundred thirty-one (15%) were malignant, 42 (5%) were suspicious for malignancy, 687 (79%) were benign, and five (1%) were lobular carcinoma in situ. Of the 42 patients with suspicious findings 38 underwent biopsy. Ten were malignant and 28 benign. Of the 687 patients with benign pathology, 377 had follow-up available with a mean length of 1.7 years. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of SCNB for benign lesions in our study are all 100 per cent. Eight lesions were worrisome and await final analysis. Of 687 patients with benign lesions 310 were lost to follow-up. This study suggests that patients with a benign diagnosis should be returned to routine mammography. These data also extend the reported follow-up to 1.7 years and establish an acceptable level of accuracy for SCNB. The lost patients remind us that follow-up is essential despite a benign diagnosis.

The role of Ca2+ feedback in shaping InsP3-evoked Ca2+ signals in mouse pancreatic acinar cells.

1. Cytosolic Ca2+ has been proposed to act as both a positive and a negative feedback signal on the inositol trisphosphate (InsP3) receptor. However, it is unclear how this might affect the Ca2+ response in vivo. 2. Mouse pancreatic acinar cells were whole-cell patch clamped to record the Ca2+-dependent chloride (Cl(Ca)) current spikes and imaged to record the cytosolic Ca2+ spikes elicited by the injection of Ins(2,4,5)P3. Increasing concentrations of Ca2+ buffer (up to 200 microM EGTA or BAPTA) were associated with the appearance of steps in the current activation phase and a prevalence of smaller-amplitude Cl(Ca) spikes. Imaging experiments showed that with increased buffer the secretory pole cytosolic Ca2+ signal became fragmented and spatially discrete Ca2+ release events were observed. 3. At higher buffer concentrations (200-500 microM), increasing concentrations of EGTA increased spike frequency and reduced spike amplitude. In contrast, BAPTA decreased spike frequency and maintained large spike amplitudes. 4. We conclude that, during InsP3-evoked spiking, long-range Ca2+ feedback ( approximately 2-4 microm) shapes the rising phase of the Ca2+ signal by acting to co-ordinate discrete Ca2+ release events and short-range ( approximately 40 nm) Ca2+ feedback acts to inhibit further Ca2+ release.