Success rate of immediately loaded implants in the posterior zone.

Dental implants are considered an ideal treatment for a missing single tooth. Immediate loading of implants can hasten the procedure, providing comfort to the patients. Recently, immediate loading of implants has gained much importance as it helps hasten the procedure and provides more comfort to patients. A previous systematic review published 5 years ago compared the success rates between immediate and conventional loading. There are several factors that influence the success rate of implants that were not discussed in detail in the previous review. Hence, the present systematic review is done to report differences in the outcomes from single implant restorations of missing teeth in the posterior region in patients who were subjected to immediate loading and conventional loading. A follow up for 1 year was done. Electronic databases of Medline, Scopus, and Web of Science were searched for publications in the English Language during May 2021. The search results yielded 306 articles, out of which 225 were excluded based on title and abstract screening. Screening of the remaining 81 full text articles yielded 14 original research articles that satisfied the predefined inclusion criteria. Meta analysis was not possible due to the heterogeneity of the data. The overall success rate of the immediate loading of a single implant is 94.31%. Implants in the maxillary region had a higher survival rate than those in the mandibular region. The age range between 18 and 80 years showed good prognosis and outcomes in older individuals. Good oral hygiene was emphasized for all patients to prevent any secondary conditions or delays in healing.

Prevalence of electronic cigarette usage among medical students in Saudi Arabia - A systematic review.

The systematic review aimed to report the prevalence of electronic cigarette (e-cigarette) usage among medical students in Saudi Arabia. Electronic databases were searched for scientific research articles published from January 2010 until December 2020. The data search was performed in electronic search engines such as PubMed, Google Scholar, Scopus, Web of Science, Medline, Embase, Cochrane, and Saudi Digital Library. A total of five research articles that qualified the eligibility criteria were analyzed for qualitative data. The sample size in the included studies ranged from 229 to 1007 participants. The prevalence of e-cigarette usage ranged from 10.6% to 27.7% among medical students in Saudi Arabia. Studies have also reported that the prevalence of e-cigarette usage is higher among the male population in comparison with the female population. The prevalence of e-cigarette usage among medical students in Saudi Arabia is high. Similar to tobacco smoking, e-cigarette usage is a major public health issue and concern among the younger population because they have potential benefits in some and are harmful to some and also it is still unclear whether they are effective for quitting smoking. Regulatory bodies must focus and initiate strict laws and policies to minimize the sales of these products to the younger population. Health promotion strategies need to be developed to reduce the usage of e-cigarettes.

Systemic mastocytosis identified in two women developing fragility fractures during lactation.

Two women presenting with fragility fractures during lactation had bone mineral density (BMD) reduced more greatly than usually associated with lactation. The first woman was 29 years old with a BMD T-score of - 3.2 SD at the spine and- 2.0 SD at the femoral neck. The second woman was 35 years old with a BMD T-score of - 4.5 SD at the spine and - 2.8 SD at the femoral neck. Both women had increased cortical porosity and reduced trabecular density. Investigation identified an elevated serum tryptase, and marrow biopsy confirmed the diagnosis of mastocytosis. Lactation causes bone loss, but the occurrence of fractures in the setting of severe deficits in BMD and microstructural deterioration signals the need to consider additional causes of bone loss.

Native valve endocarditis caused by Kocuria rosea complicated by peripheral mycotic aneurysm in an elderly host.

Infective endocarditis still remains a dreaded illness among treating physicians because of the disease course, its need for meticulous antibiotic management, complications, and overall morbidity. Peripheral mycotic aneurysms are a rarely reported complication of infective endocarditis. Mycotic aneurysms occur in about 5%-10% of cases of infective endocarditis, and most of them involve the intracranial vessels. Here, we report a case of native valve endocarditis in a 74-year-old man caused by Kocuria rosea. He presented with septic shock and acute kidney injury. His illness was complicated by a right popliteal artery mycotic aneurysm. He was treated with intravenous ceftriaxone and vancomycin. The mycotic aneurysm needed aneurysmectomy and anastomosis with a graft.

High CIP2A levels correlate with an antiapoptotic phenotype that can be overcome by targeting BCL-XL in chronic myeloid leukemia.

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a predictive biomarker of disease progression in many malignancies, including imatinib-treated chronic myeloid leukemia (CML). Although high CIP2A levels correlate with disease progression in CML, the underlying molecular mechanisms remain elusive. In a screen of diagnostic chronic phase samples from patients with high and low CIP2A protein levels, high CIP2A levels correlate with an antiapoptotic phenotype, characterized by downregulation of proapoptotic BCL-2 family members, including BIM, PUMA and HRK, and upregulation of the antiapoptotic protein BCL-XL. These results suggest that the poor prognosis of patients with high CIP2A levels is due to an antiapoptotic phenotype. Disrupting this antiapoptotic phenotype by inhibition of BCL-XL via RNA interference or A-1331852, a novel, potent and BCL-XL-selective inhibitor, resulted in extensive apoptosis either alone or in combination with imatinib, dasatinib or nilotinib, both in cell lines and in primary CD34(+) cells from patients with high levels of CIP2A. These results demonstrate that BCL-XL is the major antiapoptotic survival protein and may be a novel therapeutic target in CML.

The transrepression arm of glucocorticoid receptor signaling is protective in mutant huntingtin-mediated neurodegeneration.

The unfolded protein response (UPR) occurs following the accumulation of unfolded proteins in the endoplasmic reticulum (ER) and orchestrates an intricate balance between its prosurvival and apoptotic arms to restore cellular homeostasis and integrity. However, in certain neurodegenerative diseases, the apoptotic arm of the UPR is enhanced, resulting in excessive neuronal cell death and disease progression, both of which can be overcome by modulating the UPR. Here, we describe a novel crosstalk between glucocorticoid receptor signaling and the apoptotic arm of the UPR, thus highlighting the potential of glucocorticoid therapy in treating neurodegenerative diseases. Several glucocorticoids, but not mineralocorticoids, selectively antagonize ER stress-induced apoptosis in a manner that is downstream of and/or independent of the conventional UPR pathways. Using GRT10, a novel selective pharmacological modulator of glucocorticoid signaling, we describe the importance of the transrepression arm of the glucocorticoid signaling pathway in protection against ER stress-induced apoptosis. Furthermore, we also observe the protective effects of glucocorticoids in vivo in a Drosophila model of Huntington's disease (HD), wherein treatment with different glucocorticoids diminished rhabdomere loss and conferred neuroprotection. Finally, we find that growth differentiation factor 15 has an important role downstream of glucocorticoid signaling in antagonizing ER stress-induced apoptosis in cells, as well as in preventing HD-mediated neurodegeneration in flies. Thus, our studies demonstrate that this novel crosstalk has the potential to be effectively exploited in alleviating several neurodegenerative disorders.

Evaluation and critical assessment of putative MCL-1 inhibitors.

High levels of BCL-2 family proteins are implicated in a failed/ineffective apoptotic programme, often resulting in diseases, including cancer. Owing to their potential as drug targets in cancer therapy, several inhibitors of BCL-2 family proteins have been developed. These primarily target specific members of the BCL-2 family, particularly BCL-2 and BCL-XL but are ineffective against MCL-1. Major efforts have been invested in developing inhibitors of MCL-1, which is commonly amplified in human tumours and associated with tumour relapse and chemoresistance. In this report, the specificity of several BCL-2 family inhibitors (ABT-263, UCB-1350883, apogossypol and BH3I-1) was investigated and compared with putative MCL-1 inhibitors designed to exhibit improved or selective binding affinities for MCL-1 (TW-37, BI97C1, BI97C10, BI112D1, compounds 6 and 7, and MCL-1 inhibitor molecule (MIM-1)). ABT-263, BI97C1, BI112D1, MIM-1 and TW-37 exhibited specificity in inducing apoptosis in a Bax/Bak- and caspase-9-dependent manner, whereas the other agents showed no killing activity, or little or no specificity. Of these inhibitors, only ABT-263 and UCB-1350883 induced apoptosis in a BCL-2- or BCL-XL-dependent system. In cells that depend on MCL-1 for survival, ABT-263 and TW-37 induced extensive apoptosis, suggesting that at high concentrations these inhibitors have the propensity to inhibit MCL-1 in a cellular context. TW-37 induced apoptosis, assessed by chromatin condensation, caspase processing and phosphatidylserine externalisation, in a BAK-dependent manner and in cells that require MCL-1 for survival. TW-37-mediated apoptosis was also partly dependent on NOXA, suggesting that derivatives of TW-37, if engineered to exhibit better selectivity and efficacy at low nanomolar concentrations, may provide useful lead compounds for further synthetic programmes. Expanded medicinal chemistry iteration, as performed for the ABT series, may likewise improve the potency and specificity of the evaluated MCL-1 inhibitors.

A novel cellular stress response characterised by a rapid reorganisation of membranes of the endoplasmic reticulum.

Canonical endoplasmic reticulum (ER) stress, which occurs in many physiological and disease processes, results in activation of the unfolded protein response (UPR). We now describe a new, evolutionarily conserved cellular stress response characterised by a striking, but reversible, reorganisation of ER membranes that occurs independently of the UPR, resulting in impaired ER transport and function. This reorganisation is characterised by a dramatic redistribution and clustering of ER membrane proteins. ER membrane aggregation is regulated, in part, by anti-apoptotic BCL-2 family members, particularly MCL-1. Using connectivity mapping, we report the widespread occurrence of this stress response by identifying several structurally diverse chemicals from different pharmacological classes, including antihistamines, antimalarials and antipsychotics, which induce ER membrane reorganisation. Furthermore, we demonstrate the potential of ER membrane aggregation to result in pathological consequences, such as the long-QT syndrome, a cardiac arrhythmic abnormality, arising because of a novel trafficking defect of the human ether-a-go-go-related channel protein from the ER to the plasma membrane. Thus, ER membrane reorganisation is a feature of a new cellular stress pathway, clearly distinct from the UPR, with important consequences affecting the normal functioning of the ER.

TRAIL-activated stress kinases suppress apoptosis through transcriptional upregulation of MCL-1.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potentially useful anticancer agent with exquisite selectivity for cancer cells. Unfortunately, many cancers show or acquire resistance to TRAIL. In this study we report that TRAIL activates a TGF-beta-activated kinase 1 --> mitogen-activated protein kinase (MAPK) kinase 3 (MKK3)/MKK6 --> p38 pathway in prostate cancer cells that transcriptionally upregulates expression of the antiapoptotic BCL-2 family member MCL-1. TRAIL alone triggered robust formation of the 'death-inducing signaling complex' (DISC), activation of the initiator caspase-8, and truncation of the BH3-only protein BID (tBID). Nevertheless, simultaneous disruption of the p38 MAPK pathway was required to suppress MCL-1 expression, thereby allowing tBID to activate the proapoptotic BCL-2 family member BAK and stimulate mitochondrial outer membrane permeabilization (MOMP). Release of the inhibitor-of-apoptosis (IAP) antagonist, Smac/DIABLO, from the intermembrane space was sufficient to promote TRAIL-induced apoptosis, whereas release of cytochrome c and activation of the apoptosome was dispensable. Even after MOMP, however, mitochondrial-generated reactive oxygen species (ROS) activated a secondary signaling pathway, involving c-Jun N-terminal kinases (JNKs), that similarly upregulated MCL-1 expression and partially rescued some cells from death. Thus, stress kinases activated at distinct steps, before and after mitochondrial injury, mediate TRAIL resistance through maintenance of MCL-1 expression.

Blocking Na(+)/H(+) exchange reduces [Na(+)](i) and [Ca(2+)](i) load after ischemia and improves function in intact hearts.

We determined in intact hearts whether inhibition of Na(+)/H(+) exchange (NHE) decreases intracellular Na(+) and Ca(2+) during ischemia and reperfusion, improves function during reperfusion, and reduces infarct size. Guinea pig isolated hearts were perfused with Krebs-Ringer solution at 37 degrees C. Left ventricular (LV) free wall intracellular Na(+) concentration ([Na(+)](i)) and intracellular Ca(2+) concentration ([Ca(2+)](i)) were measured using fluorescence dyes. Hearts were exposed to 30 min of ischemia with or without 10 microM of benzamide (BIIB-513), a selective NHE-1 inhibitor, infused for 10 min just before ischemia or for 10 min immediately on reperfusion. At 2 min of reperfusion, BIIB-513 given before ischemia decreased peak increases in [Na(+)](i) and [Ca(2+)](i), respectively, from 2.5 and 2.3 times (controls) to 1.6 and 1.3 times pre-ischemia values. At 30 min of reperfusion, BIIB-513 increased systolic-diastolic LV pressure (LVP) from 49 +/- 2% (controls) to 80 +/- 2% of pre-ischemia values. BIIB-513 reduced ventricular fibrillation by 54% and reduced infarct size from 64 +/- 1% to 20 +/- 3%. First derivative of the LVP, O(2) consumption, and cardiac efficiency were also improved by BIIB-513. Similar results were obtained with BIIB-513 given on reperfusion. These data show that Na(+) loading is a marker of reperfusion injury in intact hearts in that inhibiting NHE reduces Na(+) and Ca(2+) loading during reperfusion while improving function. These results clearly implicate the ionic basis by which inhibiting NHE protects the guinea pig intact heart from ischemia-reperfusion injury.

Ischemic and anesthetic preconditioning reduces cytosolic [Ca2+] and improves Ca(2+) responses in intact hearts.

Ca(+) loading during reperfusion after myocardial ischemia is linked to reduced cardiac function. Like ischemic preconditioning (IPC), a volatile anesthetic given briefly before ischemia can reduce reperfusion injury. We determined whether IPC and sevoflurane preconditioning (SPC) before ischemia equivalently improve mechanical and metabolic function, reduce cytosolic Ca(2+) loading, and improve myocardial Ca(2+) responsiveness. Four groups of guinea pig isolated hearts were perfused: no ischemia, no treatment before 30-min global ischemia and 60-min reperfusion (control), IPC (two 2-min occlusions) before ischemia, and SPC (3.5 vol%, two 2-min exposures) before ischemia. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured at the left ventricular (LV) free wall with the fluorescent probe indo 1. Ca(2+) responsiveness was assessed by changing extracellular [Ca(2+)]. In control hearts, initial reperfusion increased diastolic [Ca(2+)] and diastolic LV pressure (LVP), and the maximal and minimal derivatives of LVP (dLVP/dt(max) and dLVP/dt(min), respectively), O(2) consumption, and cardiac efficiency (CE). Throughout reperfusion, IPC and SPC similarly reduced ischemic contracture, ventricular fibrillation, and enzyme release, attenuated rises in systolic and diastolic [Ca(2+)], improved contractile and relaxation indexes, O(2) consumption, and CE, and reduced infarct size. Diastolic [Ca(2+)] at 50% dLVP/dt(min) was right shifted by 32-53 +/- 8 nM after 30-min reperfusion for all groups. Phasic [Ca(2+)] at 50% dLVP/dt(max) was not altered in control but was left shifted by -235 +/- 40 nM [Ca(2+)] after IPC and by -135 +/- 20 nM [Ca(2+)] after SPC. Both SPC and IPC similarly reduce Ca(2+) loading, while augmenting contractile responsiveness to Ca(2+), improving postischemia cardiac function and attenuating permanent damage.

Different mechanisms of oxidative stress and neurotoxicity for Alzheimer's A beta(1--42) and A beta(25--35).

Oxidative stress induced by amyloid beta-peptide (A beta) has been implicated in the neurodegeneration observed in Alzheimer's disease (AD) brain. However, the mechanism by which the predominant form of A beta found in AD brains, A beta(1--42), causes oxidative stress and neurotoxicity remains unknown. Numerous laboratories have used the smaller 11-amino acid fragment of the full-length peptide, A beta(25--35), as a convenient alternative in AD investigations since the smaller peptide mimics several of the toxicological and oxidative stress properties of the native full-length peptide. Our observation that the truncated peptide is more rapidly toxic and causes more oxidative damage than the parent A beta(1--42) led us to investigate the cause for this enhanced toxicity of A beta(25--35) in order to gain insight into the mechanism of action of these peptides. These studies reveal that two different mechanisms may be operative in the two peptides; however, the single methionine residue in the peptides appears to play a crucial role in both mechanisms. That methionine is C-terminal in A beta(25--35) seems to be the cause for its exaggerated effects. When the next amino acid in the sequence of A beta(1--42) (valine) is appended to A beta(25--35), the resultant peptide, A beta(25--36), in which methionine is no longer C-terminal, is neither toxic to cultured neurons nor does it cause oxidative damage. Additionally, oxidizing the sulfur of methionine to a sulfoxide abrogates the damaging effects of both A beta(25--35) and A beta(1--42). The putative mechanistic role of methionine in the observed properties of A beta peptides is discussed in the context of the obtained results as is the role of A beta(1--42)-induced oxidative stress in the neurodegeneration found in AD brain.

Vulnerability of synaptosomes from apoE knock-out mice to structural and oxidative modifications induced by A beta(1-40): implications for Alzheimer's disease.

Apolipoprotein E (apoE) plays an important role in the response to central nervous system injury. The e4 allele of apoE and amyloid beta-peptide (Abeta) are associated with Alzheimer's disease (AD) and may be central to the pathogenesis of this disorder. Recent studies demonstrate evidence for neurodegeneration and increased lipid peroxidation in transgenic mice lacking apoE (KO). In the current study, synaptosomes were prepared from apoE KO mice to determine the role of apoE in synaptic membrane structure and to determine susceptibility to oxidative damage by Abeta(1-40). ApoE KO mice exhibited structural modifications to lipid and protein components of synaptosomal membranes as determined by electron paramagnetic resonance in conjunction with lipid- and protein- specific spin labels. Incubation with 5 microM Abeta(1-40) resulted in more severe oxidative modifications to proteins and lipids in apoE KO synaptosomes as measured by protein carbonyls, an index of protein oxidation, and TBARs and protein-bound 4-hydroxynonenal (HNE), markers of lipid oxidation. Together, these data support a role for apoE in the modulation of oxidative injury and in the maintenance of synaptic integrity and are discussed with reference to alterations in AD brain.

Role of spermine in amyloid beta-peptide-associated free radical-induced neurotoxicity.

The polyamines, relatively low-molecular-weight aliphatic compounds, are the main inducers of eukaryotic cell growth and proliferation. Although polyamine requirements for cell growth are well defined, their role is still enigmatic. We have previously reported that amyloid beta-peptide (A beta), the main constituent of senile plaques in Alzheimer's disease (AD) brain, is toxic to neurons through a free radical-dependent oxidative stress mechanism and that A beta(1--42), the principal form of A beta in AD brain, causes an increase in polyamine metabolism manifested by up-regulated polyamine uptake and increased ornithine decarboxylase (ODC) activity. Both effects were prevented by the free radical scavenger vitamin E. Spermine has been reported to function directly as a free radical scavenger. In the current study, we aimed to address whether up-regulation of polyamine metabolism is a defense against, or a result of, A beta-induced oxidative stress by investigating the capability of spermine to quench A beta-associated free radicals in solution and to assert a protective function of spermine in neuronal culture against A beta. Pretreatment of cultured neurons with spermine prior to A beta exposure failed to prevent A beta-induced cell death. Indeed, A beta plus spermine added to cultured neurons was even more neurotoxic than either agent alone. Additionally, inhibition of the polyamine synthesis by difluoromethylornithine (DFMO) did not protect cells from A beta-induced free radical toxicity, and stimulation of the synthesis of putrescine and spermine by the aminopropyltransferase inhibitor S-adenosyl-1,8-diamino-thiooctane (AdoDATO), rather, further enhanced A beta-induced toxicity. Although spermine is capable of scavenging free radicals generated by A beta in solution as measured by electron paramagnetic resonance (EPR) spectroscopy, the up-regulated transport of exogenously added spermine together with A beta may lead to overaccumulation of a cellular spermine pool, with resulting enhanced neurotoxicity.

Changes in [Na(+)](i), compartmental [Ca(2+)], and NADH with dysfunction after global ischemia in intact hearts.

We measured the effects of global ischemia and reperfusion on intracellular Na(+), NADH, cytosolic and mitochondrial (subscript mito) Ca(2+), relaxation, metabolism, contractility, and Ca(2+) sensitivity in the intact heart. Langendorff-prepared guinea pig hearts were crystalloid perfused, and the left ventricular (LV) pressure (LVP), first derivative of LVP (LV dP/dt), coronary flow, and O(2) extraction and consumption were measured before, during, and after 30-min global ischemia and 60-min reperfusion. Ca(2+), Na(+), and NADH were measured by luminescence spectrophotometry at the LV free wall using indo 1 and sodium benzofuran isophthalate, respectively, after subtracting changes in tissue autofluorescence (NADH). Mitochondrial Ca(2+) was assessed by quenching cytosolic indo 1 with MnCl(2). Mechanical responses to changes in cytosolic-systolic (subscript sys), diastolic (subscript dia), and mitochondrial Ca(2+) were tested over a range of extracellular [Ca(2+)] before and after ischemia-reperfusion. Both [Ca(2+)](sys) and [Ca(2+)](dia) doubled at 1-min reperfusion but returned to preischemia values within 10 min, whereas [Ca(2+)](mito) was elevated over 60-min reperfusion. Reperfusion dissociated [Ca(2+)](dia) and [Ca(2+)](sys) from contractile function as LVP(sys-dia) and the rise in LV dP/dt (LV dP/dt(max)) were depressed by one-third and the fall in LV dP/dt (LV dP/dt(min)) was depressed by one-half at 30-min reperfusion, whereas LVP(dia) remained markedly elevated. [Ca(2+)](sys-dia) sensitivity at 100% LV dP/dt(max) was not altered after reperfusion, but [Ca(2+)](dia) at 100% LV dP/dt(min) and [Ca(2+)](mito) at 100% LV dP/dt(max) were markedly shifted right on reperfusion (ED(50) +36 and +125 nM [Ca(2+)], respectively) with no change in slope. NADH doubled during ischemia but returned to normal on initial reperfusion. The intracellular [Na(+)] ([Na(+)](i)) increased minimally during ischemia but doubled on reperfusion and remained elevated at 60-min reperfusion. Thus Na(+) and Ca(2+) temporally accumulate during initial reperfusion, and cytosolic Ca(2+) returns toward normal, whereas [Na(+)](i) and [Ca(2+)](mito) remain elevated on later reperfusion. Na(+) loading likely contributes to Ca(2+) overload and contractile dysfunction during reperfusion.

Formation of a protein-bound pyrazinium free radical cation during glycation of histone H1.

Glycation, the nonenzymatic reaction between protein amino groups and reducing sugars, induces protein damage that has been linked to several pathological conditions, especially diabetes, and general aging. Here we describe the direct identification of a protein-bound free radical formed during early glycation of histone H1 in vitro. Earlier EPR analysis of thermal browning reactions between free amino acids and reducing sugars has implicated the sugar fragmentation product glycolaldehyde in the generation of a 1,4-disubstituted pyrazinium free radical cation. In order to evaluate the potential formation of this radical in vivo, the early glycation of BSA, lysozyme, and histone H1 by several sugars (D-glucose, D-ribose, ADP-ribose, glycolaldehyde) under conditions of physiological pH and temperature was examined by EPR. The pyrazinium free radical cation was identified on histone H1 glycated by glycolaldehyde (g = 2.00539, aN = 8.01 [2N], aH = 5.26 [4H], aH = 2.72 [4H]), or ADP-ribose. Reaction of glycoaldehyde with poly-L-lysine produced an identical signal, whereas reaction with BSA or lysozyme produced only a minor unresolved singlet signal. In the absence of oxygen the signal was stable over several days. Our results raise the possibility that pyrazinium radicals may form during glycation of histone H1 in vivo.

Reduced cytosolic Ca(2+) loading and improved cardiac function after cardioplegic cold storage of guinea pig isolated hearts.

BACKGROUND: Hypothermia is cardioprotective, but it causes Ca(2+) loading and reduced function on rewarming. The aim was to associate changes in cytosolic Ca(2+) with function in intact hearts before, during, and after cold storage with or without cardioplegia (CP). METHODS AND RESULTS: Guinea pig hearts were initially perfused at 37 degrees C with Krebs-Ringer's (KR) solution (in mmol/L: Ca(2+) 2.5, K(+) 5, Mg(2+) 2.4). One group was perfused with CP solution (Ca(2+) 2.5, K(+) 18, Mg(2+) 7.2) during cooling and storage at 3 degrees C for 4 hours; another was perfused with KR. LV pressure (LVP), dP/dt, O(2) consumption, and cardiac efficiency were monitored. Cytosolic phasic [Ca(2+)] was calculated from indo 1 fluorescence signals obtained at the LV free wall. Cooling with KR increased diastolic and phasic [Ca(2+)], whereas cooling with CP suppressed phasic [Ca(2+)] and reduced the rise in diastolic [Ca(2+)]. Reperfusion with warm KR increased phasic [Ca(2+)] 86% more after CP at 20 minutes and did not increase diastolic [Ca(2+)] at 60 minutes, compared with a 20% increase in phasic [Ca(2+)] after KR. During early and later reperfusion after CP, there was a 126% and 50% better return of LVP than after KR; during later reperfusion, O(2) consumption was 23% higher and cardiac efficiency was 38% higher after CP than after KR. CONCLUSIONS: CP decreases the rise in cardiac diastolic [Ca(2+)] observed during cold storage in KR. Decreased diastolic [Ca(2+)] and increased systolic [Ca(2+)] after CP improves function on reperfusion because of reduced Ca(2+) loading during and immediately after cold CP storage.

Review: Alzheimer's amyloid beta-peptide-associated free radical oxidative stress and neurotoxicity.

Alzheimer's disease, the major dementing disorder of the elderly that affects over 4 million Americans, is related to amyloid beta-peptide, the principal component of senile plaques in Alzheimer's disease brain. Oxidative stress, manifested by protein oxidation and lipid peroxidation, among other alterations, is a characteristic of Alzheimer's disease brain. Our laboratory united these two observations in a model to account for neurodegeneration in Alzheimer's disease brain, the amyloid beta-peptide-associated oxidative stress model for neurotoxicity in Alzheimer's disease. Under this model, the aggregated peptide, perhaps in concert with bound redox metal ions, initiates free radical processes resulting in protein oxidation, lipid peroxidation, reactive oxygen species formation, cellular dysfunction leading to calcium ion accumulation, and subsequent neuronal death. Free radical antioxidants abrogate these findings. This review outlines the substantial evidence from multiidisciplinary approaches for amyloid beta-peptide-associated free radical oxidative stress and neurotoxicity and protection against these oxidative processes and cell death by free radical scavengers. In addition, we review the strong evidence supporting the notion that the single methionine residue of amyloid beta-peptide is vital to the oxidative stress and neurotoxicological properties of this peptide. Further, we discuss studies that support the hypothesis that aggregated soluble amyloid beta-peptide and not fibrils per se are necessary for oxidative stress and neurotoxicity associated with amyloid beta-peptide.

The pyrrolopyrimidine U101033E is a potent free radical scavenger and prevents Fe(II)-induced lipid peroxidation in synaptosomal membranes.

The pyrrolopyrimidine U101033E is a therapeutic compound potentially useful in stroke, head injury and other oxidative stress conditions. Electron paramagnetic resonance (EPR) techniques of spin labeling and spin trapping in conjunction with measures of lipid and protein oxidation have been used to investigate the proposed antioxidant capacity of U101033E. We report potent antioxidant activity of this agent in aqueous cell-free solution as measured by spin trapping. U101033E significantly (P<0.005) reduces the formation of the EPR active spin trap N-t-butyl-alpha-phenylnitrone (PBN)-radical adduct by 17.1% at a concentration of 1 microM, four orders of magnitude less than the concentration of PBN. As measured by the decrease in signal intensity of lipid-resident nitroxide stearate spin probes, an EPR assay for lipid peroxidation, this pyrrolopyrimidine compound efficiently protected against hydroxyl radical-induced lipid peroxidation in cortical synaptosomal membranes deep within the membrane bilayer, but not closer to the membrane surface. In addition, U101033E partially prevents synaptosomal protein oxidation in the presence of Fe(II); however, U101033E demonstrates some protein oxidative effects itself. These results are supportive of the proposed role of U101033E as a lipid-specific antioxidant, especially for protection against lipid peroxidation that occurs deep within the membrane bilayer, but raise some potential concerns about the oxidative nature of this agent toward proteins.

In vitro and in vivo oxidative stress associated with Alzheimer's amyloid beta-peptide (1-42)

The amyloid beta-peptide (A beta)-associated free radical oxidative stress model for neuronal death in Alzheimer's disease (AD) brain predicts that neuronal protein oxidation is a consequence of A beta-associated free radicals [8]. In this study we have used both in vitro and in vivo models of beta-amyloid (A beta) toxicity to detect free radical induced oxidative stress by the measure of protein carbonyl levels. These model systems employed cultured hippocampal neurons exposed to exogenous synthetic A beta(1-42) and transgenic Caenorhabditis elegans (C. elegans) animals expressing A beta(1-42). We also investigated the importance of the A beta(1-42) Met35 residue for free radical formation in peptide solution and for peptide-induced protein oxidation and neuronal toxicity in these model systems. A beta(1-42) in solution yielded an EPR spectrum, suggesting that free radicals are associated with this peptide; however, neither the reverse [A beta(42-1)] nor methionine-substituted peptide [A beta(1-42)Met35Nlc] gave significant EPR spectra, suggesting the importance of the methionine residue in free radical formation. A beta(1-42) addition to cultured hippocampal neurons led to both neurotoxicity (30.1% cell death, p < 0.001) and increased protein oxidation (158% of controls, p < 0.001). and both of those effects were not observed with reverse or Met35Nle substituted peptides. C. elegans transgenic animals expressing human A beta(1-42) also had significantly increased in vivo protein carbonyls (176% of control animals, p < 0.001), consistent with our model. In contrast, transgenic animals with a Met35cys substitution in A beta(1-42) showed no increased protein carbonyls in vivo, in support of the hypothesis that methionine is important in A beta-associated free radical oxidative stress. These results are discussed with reference to the A beta-associated free radical oxidative stress model of neurotoxicity in AD brain.