Effects of cytosolic Ca2+ on the Ca2+ content of the sarcoplasmic reticulum in saponin-permeabilized rat ventricular trabeculae

 Rat ventricular trabeculae were mounted for isometric tension recording, and then permeabilized with saponin. The Ca²⁺ concentration ([Ca²⁺]) within the permeabilized preparation (cytosolic [Ca²⁺]) was monitored continuously using Indo-1 and the integrals of Ca²⁺ transients resulting from brief caffeine application used as an index of the sarcoplasmic reticulum (SR) Ca²⁺ content. The relationship between SR Ca²⁺ content and cytosolic [Ca²⁺] was studied within the reported physiological range (i.e. 50–250 nmol · l^–1 Ca²⁺). Increasing cytosolic [Ca²⁺] from 50 nmol · l^–1 to 250 nmol · l^–1 increased the steady-state SR Ca²⁺ content about threefold. However, increasing [Ca²⁺] above 250 nmol · l^–1 typically resulted in spontaneous SR Ca²⁺ release, with no further increase in SR Ca²⁺ content. The SR Ca²⁺ content increased only slowly when cytosolic [Ca²⁺] was increased; it was unchanged 20 s after a rapid increase in cytosolic [Ca²⁺], but increased progressively to a new steady-state level during the following 1–2 min. In a parallel series of experiments using intact papillary muscles, increasing extracellular [Ca²⁺] (from 0.5 to 5 mmol · l^–1) significantly increased twitch tension within 20 s of the solution change. These results support previous suggestions that the SR Ca²⁺ content may increase when diastolic cytosolic [Ca²⁺] rises during inotropic interventions such as increased stimulus rate or extracellular [Ca²⁺]. However, the rate at which SR Ca²⁺ responds to changes in cytoplasmic [Ca²⁺] within the diastolic range does not appear rapid enough to explain the early potentiation of twitch tension in intact preparations after an increase in extracellular [Ca²⁺]. Received: 26 August 1997 / Accepted: 28 October 1997     

Heavily pigmented melanocytic neoplasms: comparison of two melanin-bleaching techniques and subsequent immunohistochemical staining

The effect of melanin bleaching using permanganate/oxalate and dilute hydrogen peroxide on subsequent immunohistochemical staining of heavily pigmented melanocytic neoplasms is investigated. Permanganate/oxalate precluded the use of some antibodies but allowed much faster bleaching times, whereas dilute hydrogen peroxide enabled a full range of antibodies to be used, yet bleaching times were far longer. Each technique has advantages; however, the choice of method should be determined by the nature of the information needed to make a diagnosis and the speed at which a report is required.     

Quantification of mitral valvular incompetence

The hemodynamic and angiographic data of 147 individuals were analyzed in an attempt to assess the value of three techniques used in the diagnosis of mitral incompetence. One hundred patients had clinical evidence of mitral incompetence (group A) and 47 had normal hemodynamics (group B). The degree of mitral incompetence was assessed in all 147 individuals by two methods: determination of a regurgitant index (RI) using indicator dilution curves and determination of a regurgitant fraction (RF) using left ventricular volumes. In 26 patients of group A and 26 individuals in group B mitral incompetence was also assessed by cineangiocardiography. Each of these methods was compared with the clinical and hemodynamic evidence of mitral valvular incompetence. Both the determination of RI by dye dilution curves and RF by angiocardiography were found to be useful in separating normal individuals from patients with mitral valvular incompetence. Severe mitral incompetence is associated with an RI greater than 35% and with an RF greater than 55%. The degree of incompetence by either method was not well correlated with any independent hemodynamic variable. The use of cine angiocardiography to quantify the degree of mitral incompetence was found to be too subjective, depending on the observer, and thus less useful.     

Effects of verapamil on the extracellular K+ rise during myocardial ischaemia in dogs

The effects of verapamil on the [K+]o rise produced by myocardial ischaemia were assessed in 26 open chest mongrel dogs. Ischaemia was produced by intermittent occlusion of the LAD artery (15 dogs) or by reduction of flow of the cannulated LAD (11 dogs). Specially constructed valinomycin K+ sensitive electrodes were inserted into the mid myocardium in the central zone of ischaemia (CZ); in the margin (MZ) and in the nonischaemic zone (NZ). Occlusion of the coronary artery under controlled conditions produced significant [K+]o rise, greater in the CZ than in the MZ. During the infusion of verapamil the ischaemic [K+]o rise was substantially reduced in both zones. During controlled 75% reduction of coronary flow the [K+]o reached a plateau that remained stable until reperfusion was re-established. During verapamil infusion, the plateau showed a steady decline, both in the CZ and in the MZ. The changes in [K+]o produced by verapamil, during myocardial ischaemia are probably due to: coronary dilatation of the marginal arteries and+or to a reduction of the late cellular K+ conductance due to a decrease in the intracellular Ca2+, produced by verapamil.     

Intrinsic and extrinsic risk factors for muscle strains in Australian football

Muscle strains are common injuries in Australian football and other sports involving sprinting. Between 1992 and 1999, 83,503 player-matches in the Australian Football League were analyzed for risk of muscle strain injuries using logistic regression analysis. There were 672 hamstring, 163 quadriceps, and 140 calf muscle strain injuries. All three types of muscle strains were associated with significant risk factors. For all injuries, the strongest risk factor was a recent history of that same injury and the next strongest risk factor was a past history of the same injury. History of one type of muscle strain increased the risk for certain types of other muscle strains. Age was a risk factor for hamstring and calf muscle strains (even when adjusted for injury history) but was not a risk factor for quadriceps muscle strains. Quadriceps muscle injuries were more common in shorter players and were more likely when there had been less rainfall at the match venue in the previous week. Quadriceps muscle injuries were significantly more common in the dominant kicking leg, whereas hamstring and calf muscle injuries showed no difference in frequency between the dominant and nondominant legs.     

The association of red blood cell n‐3 and n‐6 fatty acids with bone mineral density and hip fracture risk in the women's health initiative

Omega‐3 (n‐3) and omega‐6 (n‐6) polyunsaturated fatty acids (PUFA) in red blood cells (RBCs) are an objective indicator of PUFA status and may be related to hip fracture risk. The primary objective of this study was to examine RBC PUFAs as predictors of hip fracture risk in postmenopausal women. A nested case‐control study (n = 400 pairs) was completed within the Women's Health Initiative (WHI) using 201 incident hip fracture cases from the Bone Mineral Density (BMD) cohort, along with 199 additional incident hip fracture cases randomly selected from the WHI Observational Study. Cases were 1:1 matched on age, race, and hormone use with non–hip fracture controls. Stored baseline RBCs were analyzed for fatty acids using gas chromatography. After removing degraded samples, 324 matched pairs were included in statistical analyses. Stratified Cox proportional hazard models were constructed according to case‐control pair status; risk of fracture was estimated for tertiles of RBC PUFA. In adjusted hazard models, lower hip fracture risk was associated with higher RBC α‐linolenic acid (tertile 3 [T3] hazard ratio [HR]: 0.44; 95% confidence interval [CI], 0.23–0.85; p for linear trend 0.0154), eicosapentaenoic acid (T3 HR: 0.46; 95% CI, 0.24–0.87; p for linear trend 0.0181), and total n‐3 PUFAs (T3 HR: 0.55; 95% CI, 0.30–1.01; p for linear trend 0.0492). Conversely, hip fracture nearly doubled with the highest RBC n‐6/n‐3 ratio (T3 HR: 1.96; 95% CI, 1.03–3.70; p for linear trend 0.0399). RBC PUFAs were not associated with BMD. RBC PUFAs were indicative of dietary intake of marine n‐3 PUFAs (Spearman's rho = 0.45, p < 0.0001), total n‐6 PUFAs (rho = 0.17, p < 0.0001) and linoleic acid (rho = 0.09, p < 0.05). These results suggest that higher RBC α‐linolenic acid, as well as eicosapentaenoic acid and total n‐3 PUFAs, may predict lower hip fracture risk. Contrastingly, a higher RBC n‐6/n‐3 ratio may predict higher hip fracture risk in postmenopausal women. © 2013 American Society for Bone and Mineral Research.     

Absence of the t(14;18) chromosomal translocation in primary cutaneous B-cell lymphoma

BACKGROUND: The t(14;18)(q32;q21) chromosomal translocation is found in the majority of nodal follicular lymphomas and in a lower percentage of systemic high-grade diffuse large B-cell lymphomas. The translocation results in the juxtaposition of the bcl-2 gene on chromosome 18 with the immunoglobulin heavy chain joining region on chromosome 14. Bcl-2 protein prevents apoptosis and the translocation leads to overexpression of a functionally normal Bcl-2 protein that prevents apoptosis of neoplastic cells. OBJECTIVES: The purpose of our study was to analyse cases of primary cutaneous B-cell lymphoma (PCBCL) for the presence of the t(14;18) translocation and to correlate the results with Bcl-2 expression and histological subtype. METHODS: Forty-four cutaneous B-cell lymphoid proliferations (36 PCBCL, four follicular B-cell lymphomas with cutaneous presentation and four reactive B-cell infiltrates) were analysed by polymerase chain reaction amplification and polyacrylamide gel electrophoresis using consensus primers for the joining region on the immunoglobulin heavy chain gene in combination with either a primer for the major breakpoint region (MBR) or the minor cluster region (mcr) on chromosome 18. RESULTS: None of 36 PCBCL analysed demonstrated a t(14;18) translocation; however, three of four systemic follicular B-cell lymphomas presenting in the skin were found to have a translocation in the MBR, which was confirmed by sequence analysis. Correlation with Bcl-2 immunostaining showed that of seven patients with high-grade cutaneous diffuse large B-cell lymphoma, four were Bcl-2 positive but had no evidence of a t(14;18) translocation. In the five cases classified as primary cutaneous follicle centre cell lymphoma, the neoplastic cells within the germinal centres failed to express Bcl-2. However, Bcl-2-positive neoplastic cells were present in all four cases of systemic follicular lymphoma, including the case that did not show a t(14;18) translocation. In all cases of marginal zone lymphoma the marginal zone lymphocytes were Bcl-2 positive. CONCLUSIONS: These findings indicate that the t(14;18) translocation does not occur in PCBCL, which suggests the involvement of different pathogenetic mechanisms compared with their nodal counterparts. Furthermore, the detection of a t(14;18) translocation in cutaneous B-cell lymphoma should suggest the presence of systemic disease, which underlies the need for exhaustive staging procedures.     

Pseudocarcinomatous change in lymphomatoid papulosis and primary cutaneous CD30+ lymphoma: a clinicopathologic and immunohistochemical study of 6 patients

We report 6 cases of pseudoepitheliomatous hyperplasia (PEH) mimicking squamous cell carcinoma in association with an atypical CD30+ dermal infiltrate. Three patients had lymphomatoid papulosis type A, and 3 patients had cutaneous CD30+ lymphoma. All 6 cases showed histologic evidence of PEH with keratinocyte atypia. In 4 cases there was significant atypia to prompt a diagnosis of squamous cell carcinoma. Three of these received treatment with wide local excision and 2 had been engrafted. Immunohistochemical staining for epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha) showed similar expression in lesional and perilesional skin. Epidermal growth factor receptor (EGFR) expression by the proliferating epithelium was similar to that of the suprabasal adjacent normal epidermis. There was no aberrant expression of EGF, TGF-alpha, and EGFR by atypical lymphocytes. These cases demonstrate that PEH associated with CD30+ lymphoproliferative disease may closely resemble squamous cell carcinoma, thereby leading to inappropriate diagnosis and treatment.