N95 mask reuse in a major urban hospital: COVID-19 response process and procedure.

BACKGROUND: The shortage of single-use N95 respirator masks (NRMs) during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has prompted consideration of NRM recycling to extend limited stocks by healthcare providers and facilities. AIM: To assess potential reuse via autoclaving of NRMs worn daily in a major urban Canadian hospital. METHODS: NRM reusability was assessed following collection from volunteer staff after 2-8 h use, sterilization by autoclaving and PortaCount fit testing. A workflow was developed for reprocessing hundreds of NRMs daily. FINDINGS: Used NRMs passed fit testing after autoclaving once, with 86% passing a second reuse/autoclave cycle. A separate cohort of used masks pre-warmed before autoclaving passed fit testing. To recycle 200-1000 NRMs daily, procedures for collection, sterilization and re-distribution were developed to minimize particle aerosolization risk during NRM handling, to reject NRM showing obvious wear, and to promote adoption by staff. NRM recovery ranged from 49% to 80% across 12 collection cycles. CONCLUSION: Reuse of NRMs is feasible in major hospitals and other healthcare facilities. In sharp contrast to studies of unused NRMs passing fit testing after 10 autoclave cycles, we show that daily wear substantially reduces NRM fit, limiting reuse to a single cycle, but still increasing NRM stocks by ∼66%. Such reuse requires development of a comprehensive plan that includes communication across staffing levels, from front-line workers to hospital administration, to increase the collection, acceptance of and adherence to sterilization processes for NRM recovery.

Hydrogen peroxide inhibition of nuclear protein import is mediated by the mitogen-activated protein kinase, ERK2.

H(2)O(2) alters gene expression in many cell types. Alterations in nuclear import of transcription factors or similar key proteins may be responsible for these changes. To investigate this possibility, a cytosolic nuclear import cocktail was treated with varying ¿H(2)O(2) and used in import assays. H(2)O(2) caused a dose- and time-dependent inhibition of import at concentrations as low as 100 microM. Catalase reversed this effect. H(2)O(2) treatment of permeablized cells did not affect import, suggesting that H(2)O(2) was acting on a cytosolic factor. Treatment of import cocktail with two different free radical generating systems had no effect, but treatment of permeablized cells inhibited import, suggesting H(2)O(2) works via a distinct process from hydroxyl or superoxide radicals. Pretreatment of import cocktail with genistein reversed the effect of H(2)O(2) on import. Western blotting revealed that H(2)O(2) activated ERK2. The specific MEK1/2 inhibitor, PD98059, completely blocked the effects of H(2)O(2) on import. Activated ERK2 mimicked H(2)O(2)'s effect on import. Immunocytochemistry revealed that H(2)O(2) treatment of whole cells increased cytosolic Ran/TC4 levels, an effect reversible by catalase or PD98059. These data demonstrate that H(2)O(2) inhibits nuclear protein import and that this effect is mediated by mitogen-activated protein (MAP) kinase activation, possibly by altering Ran/TC4 function.

The atherogenic effects of chlamydia are dependent on serum cholesterol and specific to Chlamydia pneumoniae.

Epidemiological investigations have linked Chlamydia pneumoniae infection to atherosclerosis. It is not clear, however, whether C. pneumoniae infection plays a causal role in the development of atherosclerosis. Mice with low-density lipoprotein receptor deficiency were induced to develop atherosclerotic lesions in aorta with a cholesterol-enriched diet that increased serum cholesterol by two- to threefold. Using this mouse model, we found that the chlamydial infection alone with either the C. pneumoniae AR39 or the C. trachomatis MoPn strain failed to induce any significant atherosclerotic lesions in aorta over a period of nine months. However, in the presence of a high-cholesterol diet, infection with the C. pneumoniae AR39 strain significantly exacerbated the hypercholesterolemia-induced atherosclerosis, demonstrating that a hypercholesterolemic condition is required for the C. pneumoniae to aggravate the development of atherosclerosis. Although both AR39 and MoPn antigens were detected in aorta of mice infected with the corresponding strains, only mice infected with the C. pneumoniae strain AR39 displayed enhanced atherosclerotic lesions, suggesting that the C. pneumoniae species may possess a unique atherogenic property. This study may provide a model for further understanding the mechanisms of C. pneumoniae atherogenesis and evaluating chlamydial intervention strategies for preventing the advancement of atherosclerotic lesions enhanced by C. pneumoniae infection.

Chronic exposure of smooth muscle cells to minimally oxidized LDL results in depressed inositol 1,4,5-trisphosphate receptor density and Ca(2+) transients.

Oxidized LDL (oxLDL) (0.1 mg/mL) increased [Ca(2+)](i) in vascular smooth muscle cells (VSMCs) within 5 to 10 seconds of incubation. This increase was mediated via an inositol 1,4,5-trisphosphate (IP(3))-dependent release of Ca(2+) from the sarcoplasmic reticulum. However, atherosclerosis is a gradual process in which VSMCs are more likely exposed to low concentrations of oxLDL over extended periods rather than acute exposures. It is very possible, therefore, that lower [oxLDL] and longer exposure times may induce a very different response with regard to regulation of [Ca(2+)](i). VSMCs were incubated with 4- to 100-fold lower [oxLDL] for up to 6 days. The conditions were not cytotoxic. Basal [Ca(2+)](i) was not altered. Surprisingly, however, after chronic exposure to oxLDL, a brief addition of oxLDL (0.1 mg/mL) or norepinephrine failed to elicit the expected rise in Ca(2+)(i). Because the acute effects of oxLDL on control cells were mediated through an IP(3)-dependent pathway, we investigated the integrity of the VSMC IP(3) receptors. Immunocytochemical analysis and Western blots revealed a depression in the density of IP(3) receptors after chronic exposure of VSMCs to oxLDL. These changes in IP(3) receptors have significance under atherosclerotic conditions as well. Immunocytochemical analysis revealed a decrease in IP(3) receptor density in the medial layer under atherosclerotic plaques in situ. Our data, therefore, demonstrate a striking difference between the acute and chronic effects of oxLDL on VSMC calcium. Whereas acute exposure to oxLDL stimulates [Ca(2+)](i), chronic exposure results in depressed Ca(2+) transients, apparently through a decrease in IP(3) receptor density. These changes have functional implications for the atherosclerotic vessel in vivo, and our data implicates oxLDL in this process.

Na+-H+ exchange in cardiac sarcolemmal vesicles.

The transport of Na+ by a purified sarcolemmal vesicular preparation from canine ventricular tissue was studied as a function of both internal and external pH. The uptake of Na+ into sarcolemmal vesicles increased upon raising the extravesicular pH of the reaction medium. Half-maximal uptake of Na+ was observed at a pHo of about 8.1 and maximal uptake occurred at pH 8.6. The uptake of Na+ by sarcolemma was also dependent upon the intravesicular pH. Na+ uptake into sarcolemmal vesicles was greatly attenuated in the absence of a H+ gradient across the membrane. Transport of Na+ was potently inhibited by amiloride, a known blocker of Na+-H+ exchange. LiCl was also an effective inhibitor of Na+ transport. In the presence of optimal H+ gradients, Na+ uptake was linear for the first 5 seconds of the reaction and exhibited a Vmax of 290 nmol Na+/mg per min and a KNa of 3.5 mM. These experiments strongly indicate the presence of a Na+-H+ exchange system in cardiac sarcolemma. This activity appeared to be relatively specific for this membrane fraction. The identification of Na+-H+ exchange activity in a sarcolemmal vesicular fraction from the heart will permit extensive characterization of the regulation and kinetics of this antiporter in future investigations.

Two major antigens of heart sarcolemma are Ca2(+)-binding glycoproteins that copurify with the dihydropyridine receptor.

Ca2+ binding has been studied in isolated heart sarcolemmal membranes using the 45Ca overlay technique. 45Ca bound to two sarcolemmal polypeptides of 125 kDa and 97 kDa in preparations from dog, rabbit, cow and pig. During fractionation on DEAE ion-exchange and wheat-germ lectin affinity columns, the two Ca2(+)-binding polypeptides copurified with the dihydropyridine receptor associated with the voltage gated Ca2+ channel. These polypeptides were the major proteins in the isolated fraction as judged by silver staining in SDS-PAGE. Antisera raised against purified dog heart, sarcolemma indicated that the 125 and 97 kDa polypeptides were highly antigenic components of this membrane. The antisera cross-reacted with similar polypeptides in cardiac sarcolemmal preparations from rabbit, cow and pig, but not sarcoplasmic reticulum membranes. Purified antibodies against the 125 kDa polypeptide did not cross-react with the 97 kDa polypeptide, while antibodies against the 97 kDa polypeptide did not cross-react with the 125 kDa polypeptide. Both the 125 kDa and 97 kDa polypeptides bound wheat-germ lectin, suggesting both were glycoproteins. It is unlikely that these Ca2+ binding glycoproteins represent subunits of the dihydropyridine receptor-Ca2+ channel in this membrane.

Beneficial effects of verapamil in diabetic cardiomyopathy.

It has been suggested that the occurrence of an intracellular Ca2+ overload may result in the development of diabetic cardiomyopathy, which is associated with depletion of high-energy phosphate stores and a derangement of ultrastructure and cardiac dysfunction. Accordingly, the effects of verapamil, a Ca2+ antagonist, on cardiac function, ultrastructure, and high-energy phosphate stores in the myocardium were evaluated in rats made diabetic by an intravenous injection of streptozocin (65 mg/kg). Four weeks after the induction of diabetes, the animals were treated with three doses (2, 4, or 8 mg.kg-1.day-1) of verapamil for 4 wk until they were used for the measurement of different parameters. Untreated diabetic animals had slower heart rates, depressed rate of contraction and rate of relaxation, lower peak left ventricular systolic pressure, and elevated left ventricular diastolic pressure. All of these changes were significantly improved in diabetic rats receiving verapamil treatment. The beneficial effects of verapamil were more evident with higher doses (8 mg.kg-1.day-1) than with the lower doses (2 mg.kg-1.day-1). The diabetic animals also showed alterations in myocardial high-energy phosphate stores and exhibited evidence of ultrastructural damage; these abnormalities were improved by verapamil treatment without affecting their hyperglycemic status. Our results demonstrate that verapamil is capable of preventing diabetes-induced myocardial changes and support the involvement of Ca2+ in the cardiac pathology during diabetes.

Regulation of intracellular Ca2+ in the heart during diabetes.

Cardiovascular disease is a significant medical problem. The diabetic population is even more susceptible to cardiovascular complications and heart failure than non-diabetic patients. Atherosclerotic complications, a neuropathy and microvascular lesions have all been implicated causally in the accelerated cardiovascular disease during diabetes. However, one mechanism which may participate in the abnormalities in heart performance demonstrated during diabetes and may also contribute to heart failure in the diabetic is a derangement in the capacity of the myocardial cell to regulate its [Ca2+]. The purpose of this treatise is to identify the current controversies and conclusions available regarding the specific defects in Ca2+ flux thought to contribute to these cardiac defects during diabetes mellitus.

Involvement of lipoproteins, free radicals, and calcium in cardiovascular disease processes.

Low density lipoproteins have the capacity to alter cell calcium concentrations of a wide variety of cell types. The precise mechanism of physical interaction of the LDL or its products with the cell is not defined yet. There is more agreement about the calcium transport pathway affected. Most studies show an ability of LDL to alter transsarcolemmal calcium flux, probably through the slow calcium channel. However, internal stores of calcium like the sarcoplasmic reticulum also appear to be altered. These effects of LDL on cellular calcium homeostasis have potential importance in both physiological and disease settings. Oxidised LDL has even more potential significance than the native LDL in disease conditions. Free radical mediated oxidation of LDL during atherosclerotic and ischaemic conditions creates a molecule with even greater potency for altering cell calcium and ultimately cell function and viability. The interaction of this trio of compounds--LDL, free radicals, and cellular calcium--may be critical for the mechanism of pathogenesis in specific cardiovascular diseases. It will be important in the future to identify new therapeutic strategies to prevent their interaction.

Induction of expression of the sodium-hydrogen exchanger in rat myocardium.

OBJECTIVE: The aim was to examine the regulation of the cardiac Na+/H+ exchanger NHE-1 isoform mRNA in response to ischaemia and acidosis in the mammalian myocardium. METHODS: Male Sprague Dawley rat hearts were perfused in a non-circulated retrograde fashion according to the Langendorff method. Hearts were perfused for 3 h at flow rates of either 10 ml.min-1 (control), or 3, 1, or 0 ml.min-1 (ischaemia) followed by 5 min of reperfusion. Hearts were immediately frozen in liquid N2, and stored at -80 degrees C until ready for RNA isolation. Northern blot analysis was used to examine expression of the NHE-1 isoform of the Na+/H+ exchanger message in these isolated perfused hearts. Activity of the Na+/H+ exchanger was assessed in primary cultures of neonatal rat myocytes under either control conditions or after treatment with chronic, low external pH. RESULTS: A decrease in developed tension and an increase in resting tension was observed which was dependent upon the severity of the ischaemic episode. Low flow ischaemia of 3 ml.min-1 caused increased Na+/H+ exchanger message levels, while perfusion at more reduced flow rates eliminated the increase. Treatment of primary cultures of isolated myocytes with low external pH resulted in increased ability to recover from an acute acid load. CONCLUSIONS: Low flow ischaemia can increase the Na+/H+ exchanger message in the intact mammalian myocardium. More severe ischaemia prevents the increase, suggesting that severely damaged tissue may not be capable of the ischaemic response. Primary cultures of isolated myocytes can respond to chronic low external pH by increasing Na+/H+ exchanger activity.

Sarcolemmal alterations during the development of genetically determined cardiomyopathy.

The purpose of this study was to identify alterations in specific enzyme and Ca2+ binding activities in cardiac sarcolemmal fractions from UM-X7.1 myopathic Syrian hamsters during the development of cardiomyopathy. Experimental and healthy control animals were examined from 25 to 200 days of age. Sarcolemmal Na+, K+-ATPase activity was depressed in the myopathic hamsters throughout the time course of this study. Sarcolemmal ATP-independent Ca2+ binding was found to be depressed in experimental animals as early as 55 days of age. Ca2+ -stimulated, Mg2+ -dependent ATPase activity was depressed in the experimental animals by 90 days of age and this decrease in enzyme activity was accompanied by a decrease in ATP-dependent Ca2+ binding capacity of the sarcolemmal membranes. Mg2+ -ATPase and Ca2+ -ATPase activities were only affected in the latter stages of the disease (155 to 200 days old). NaF, epinephrine and Gpp(NH)p stimulation of the sarcolemmal adenylate cyclase activity was also observed to be attenuated during the latter stages of the disease. These defects in adenylate cyclase system of the sarcolemmal fraction appeared specific since basal adenylate cyclase activity was not altered at any age studied. The results demonstrate that the earliest lesions in sarcolemmal activity in myopathic hamster heart occur in Na+, K+-ATPase and ATP-independent Ca2+ binding capacity. These defects correspond temporally to the initial stages of cardiac necrotic development in this strain of myopathic hamster.

A randomized trial of the effects of ezetimibe on the absorption of omega-3 fatty acids in cardiac disease patients: A pilot study.

BACKGROUND AND AIMS: Elevated levels of circulating omega-3 polyunsaturated fatty acids like alpha linolenic acid (ALA) may be beneficial for cardiovascular health. Circulating ALA concentrations are elevated dramatically by a cholesterol supplemented diet which increases ALA bioavailability through enhanced micelle formation in the intestines. Conversely, it is possible that drugs which inhibit cholesterol metabolism in the intestine may also inhibit fatty acid absorption. The purpose of this study is to determine if a cholesterol absorption inhibitor, ezetimibe, will decrease circulating levels of ALA. METHODS AND RESULTS: Cardiac patients (n = 34) between 44 and 80 years old, requiring statin therapy to regulate blood cholesterol levels, were randomly assigned to one of four groups for a 6 week trial: 1) placebo; 2) ezetimibe therapy; 3) a supplement of flaxseed oil (containing 1.0 g ALA in 2.0 g of flaxseed oil); or 4) ezetimibe and flaxseed oil supplementation. Ingestion of flaxseed oil resulted in a significant increase in circulating ALA levels (6 ug/dl) in patients who were not given ezetimibe. However, in the presence of ezetimibe, circulating ALA levels did not increase significantly even in the presence of flax oil supplementation (a decrease of 4 ug/dl). There were no significant differences amongst the groups in terms of circulating total cholesterol, LDL, HDL, triglyceride levels in the blood. CONCLUSION: Ezetimibe therapy inhibited the absorption of omega-3 fatty acids. Patients receiving ezetimibe therapy may not receive the expected cardiovascular benefits from dietary supplementation with omega-3 fatty acids. CLINICAL TRIAL REGISTRATION: NCT00955227.

Cataract formation is prevented by administration of verapamil to diabetic rats.

The purpose of the present study was to examine the effects on cataractogenesis of daily sc administration of the Ca2+ antagonist drug verapamil to diabetic rats. Streptozotocin-induced diabetic rats were given verapamil half-way through the 8-week experimental period or during the full 8 weeks of diabetes. Verapamil administration had no effect on the high blood glucose values, low circulating insulin levels, or elevated triglyceride and cholesterol concentrations in the diabetic rats. Untreated diabetic rats had a 90% incidence of cataracts. Four weeks of verapamil administration reduced this incidence to 41%, and a full 8 weeks of drug treatment further lowered the incidence to 20%. Diltiazem, another Ca2+ antagonist, lowered the incidence of cataracts in the diabetic rats to a similar extent. Verapamil administration to the diabetic animals also partially protected against the presence of retinal microangiopathy in the diabetic animals. Lenticular hydration and lipid accumulation were only indirectly related to cataractogenesis in the diabetic rats and its protection by verapamil treatment. Lenticular electrolyte imbalance, particularly Ca2+, in the diabetic animals was closely correlated with cataract formation, and verapamil significantly reduced the alterations in these ion concentrations. The present results demonstrate the efficacy of verapamil as a protective agent against cataractogenesis and some retinal damage in diabetic animals. Most importantly, this occurs in the absence of any change in the glycemic status of the diabetic animals. The findings strongly support a role for lenticular Ca2+ imbalance in cataract development in diabetes and provide initial evidence to suggest its clinical use in the diabetic population at risk for blindness.

The importance of lipid solubility in antioxidants and free radical generating systems for determining lipoprotein proxidation.

The oxidative modification of low-density lipoprotein (LDL) plays an important role in atherosclerosis. Protecting LDL from oxidation has been shown to reduce the risk of coronary heart disease. In this study, we compared the protective effects of two lipophilic antioxidants (vitamin E and lazaroid) with two hydrophilic antioxidants (trolox and vitamin C) in the presence of several different free radical generating systems. Vitamin E (IC50 = 5.9 microM) and lazaroid (IC50 = 5.0 microM) were more effective in inhibiting lipid peroxidation caused by a Fe-ADP free radical generating system than vitamin C (IC50 = 5.2 x 10(3) microM) and trolox (IC5 = 1.2 x 10(3) microM). Preincubation of lipoproteins with a lipophilic antioxidant increased the protective effect against various free radicals. Preincubation with hydrophilic antioxidants did not have an effect. We also tested the efficacy of the antioxidants when the free radicals were generated within the lipid or the aqueous environment surrounding the LDL. For this purpose, we used the peroxyl generating azo-compounds AMVN (2,2'-azobis(2,4-dimethylvaleronitrile)) and AAPH (2,2'azobis(2-amidinopropane) dihydrochloride). All of the antioxidants tested were more effective against free radicals generated in a water soluble medium than they were against free radicals generated in a lipid environment. In conclusion, our data demonstrate that lipid solubility is an important factor for both the antioxidant and the free radical generating systems in determining the extent of lipid peroxidation in LDL. Our data also demonstrate that antioxidant efficacy in one set of experimental conditions may not necessarily translate into a similar degree of protection in another set of conditions where lipophilicity is a variable.

Oxidation of nuclear membrane cholesterol inhibits nucleoside triphosphatase activity.

Oxygen derived free radicals can oxidize membrane cholesterol. We have previously shown that cholesterol in the nuclear membrane can modulate nuclear nucleoside triphosphatase (NTPase) activity. Nucleocytoplasmic transport of peptides and mRNA via the nuclear pore complex may be regulated by the NTPase. The purpose of the present study was to determine if oxidation of nuclear cholesterol could alter NTPase activity. Nuclear membrane cholesterol was oxidized in situ with cholesterol oxidase (to selectively oxidize cholesterol) and NTPase activity measured. HPLC analysis confirmed the formation of cholesterol oxides. The activity of the NTPase was strikingly inhibited by cholesterol oxidase treatment. The Vmax of the NTPase was significantly decreased after cholesterol oxidase treatment but the Km value was unchanged. The sensitivity of NTPase activity to varying cholesterol oxidase concentrations also suggested that cholesterol located in the inner leaflet of the nuclear membrane appeared to be more important in the modulation of NTPase activity than that in the cytoplasmic leaflet. Our results indicate that oxidation of nuclear membrane cholesterol inhibits NTPase activity. These results have implications for peptide and mRNA flux across the nuclear membrane during conditions where lipid oxidation may be expected.

Susceptibility of LDL to oxidative stress in obstructive sleep apnea.

Cardiovascular diseases are more common in patients with obstructive sleep apnea (OSA) than in the general population. We hypothesized that severe hypoxemia during sleep in these patients may cause an imbalance between reactive oxygen species and the antioxidant reserve that is important for the detoxification of these molecules. We tested the hypothesis that low-density lipoproteins (LDL) in hypoxic OSA patients may be more susceptible to oxidative stress than LDL of nonhypoxic OSA patients and normal controls. Fifteen OSA patients were included in this study, six with severe hypoxia (hypoxic group) who spent more than 10 minutes during sleep with SaO2 < 85% (mean 96 minutes), and nine OSA patients (nonhypoxic group) who spent less than 10 minutes during sleep with SaO2 < 85% (mean 1.1 minutes). Six healthy nonsmoking males of the same age group were included as a control group. The susceptibility of each individual's LDL to oxidative stress was examined after free-radical challenge in vitro by assessing changes in levels of conjugated dienes. The LDL in OSA patients with severe hypoxia was not more susceptible to oxidative stress compared to the LDL of nonhypoxic OSA patients and normal controls. After 6 hours of exposure to an oxidative agent, the changes in the mean conjugated diene were not different among the three groups (p = 0.75). The time required to reach 50% of maximal absorbance was also not different, p = 0.199. Glutathione peroxidase and catalase activities in red blood cells in the hypoxic and nonhypoxic patient groups were not significantly different. One night of CPAP therapy in each patient group did not significantly change the level of the antioxidant enzymes. Our results did not show any difference in the susceptibility to oxidative stress between hypoxic and nonhypoxic OSA patients and normal controls.

Effects of chronic swimming training on cardiac sarcolemmal function and composition.

Cardiac contractile function is dependent on the integrity and function of the sarcolemmal membrane. Swimming exercise training is known to increase cardiac contractile performance. The purpose of the present study was to examine whether a swimming exercise program would alter sarcolemmal enzyme activity, ion flux, and composition in rat hearts. After approximately 11 wk of exercise training, cardiac myosin and actomyosin Ca2+-adenosinetriphosphatase (ATPase) activity was significantly higher in exercised rat hearts than in sedentary control rat hearts. Glycogen content was increased in plantaris and gastrocnemius muscles from exercised animals as was succinic dehydrogenase activity in gastrocnemius muscle of exercised rats in comparison to sedentary rat preparations. Sarcolemmal vesicles were isolated from hearts of exercise-trained and control rats. Sarcolemmal Na+-K+-ATPase and K+-p-nitrophenylphosphatase activities, Na+-Ca2+ exchange, and passive Ca2+ binding did not differ between the two groups. ATP-dependent Ca2+ uptake and 5'-nucleotidase activity were elevated in the cardiac sarcolemmal vesicles isolated from exercised animals compared with sedentary control rats. Sarcolemmal phospholipid composition was not altered by the exercise training. Our results demonstrate that swimming training in rats does not affect most parameters of cardiac sarcolemmal function or composition. However, the elevated sarcolemmal Ca2+ pump activity in exercised rats may help to reduce intracellular Ca2+ and augment cardiac relaxation rates. The enhanced 5'-nucleotidase activity may stimulate adenosine production, which could affect myocardial blood flow. The present results further our knowledge on the subcellular response of the heart to swimming training in the rat.

Cardiac effects of beta-adrenergic receptor antagonists: beta-moderators versus beta-blockers.

Two adrenergic receptor antagonists, acebutolol and propranolol, were observed to depress rabbit heart contractile force and adrenaline-stimulated adenylate cyclase activity at 1 X 10-(5) to 1 X 10-(3) M and 1 X 10-(6) to 1 X 10-(3) M concentrations, respectively. Acebutolol depressed sarcoplasmic reticular and mitochondrial calcium uptake at 5 X 10-(3) to 10-(2) M concentrations. On the other hand, propranolol was found to decrease calcium uptake activities of sarcoplasmic reticular and mitochondrial fractions at 1 X 10-(4) to 1 X 10-(2) M and 1 X 10-(3) to 1 X 10-(2) M concentrations, respectively. On the basis of these results with calcium transport systems, it is proposed that beta-antagonists with a mild depressant effect, such as acebutolol, may be called beta-moderators, whereas those with a strong effect, such as propranolol, may be called beta-blockers.

Increase in nuclear calcium in smooth muscle cells exposed to oxidized low density lipoprotein.

Vascular smooth muscle cells respond with an increase in intracellular Ca2+ within seconds after exposure to oxidized low density lipoprotein (oxLDL). This has been suggested to represent a signaling response that may have implications for gene expression. If so, oxLDL may induce increases in nuclear Ca2+ in smooth muscle cells in response to oxLDL. Aortic smooth muscle cells were exposed to 100 microg/ml oxLDL. Large, rapid increases in [Ca2+]i were observed using fluo-3 as an indicator dye to detect intracellular Ca2+ on the stage of a confocal microscope. This was also confirmed using ratiometric imaging of indo signals. These elevations appeared to be localized to the nuclear region of the cell. DNA staining of the cells confirmed its localization to the nuclear/perinuclear region of the cell. Our data demonstrate that oxLDL induces a nuclear localized elevation in Ca2+i that may have important implications for nuclear function.

Cardiovascular complications of non-insulin-dependent diabetes: the JCR:LA-cp rat.

Diabetes is a serious medical and financial burden on western societies. It is the seventh leading cause of death in the United States and Canada. The disease is due to a primary defect in glucose tolerance and carbohydrate metabolism resulting from either a deficiency of insulin (Insulin-dependent (type I) diabetes mellitus - IDDM) or a state of insulin resistance (Non-insulin-dependent (type II) diabetes mellitus - NIDDM). NIDDM comprises greater than 80% of total diabetic cases. Associated with the primary metabolic defects are equally deleterious secondary complications affecting the renal, ocular, nervous and cardiovascular systems. The cardiovascular complications account for a major proportion of diabetic mortality. As such, it is of paramount importance to develop or find an animal model expressing complications homologous to the human condition. Many models of NIDDM are available to the diabetic researcher but choosing an accurate one can be difficult. The following compares the advantages and limitations of one such model, the JCR:LA-cp rat to other NIDDM models commonly used today.