Magnetic nanoparticles for magnetic particle imaging (MPI): design and applications.

Recent advancements in medical imaging have brought forth various techniques such as magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), and ultrasound, each contributing to improved diagnostic capabilities. Most recently, magnetic particle imaging (MPI) has become a rapidly advancing imaging modality with profound implications for medical diagnostics and therapeutics. By directly detecting the magnetization response of magnetic tracers, MPI surpasses conventional imaging modalities in sensitivity and quantifiability, particularly in stem cell tracking applications. Herein, this comprehensive review explores the fundamental principles, instrumentation, magnetic nanoparticle tracer design, and applications of MPI, offering insights into recent advancements and future directions. Novel tracer designs, such as zinc-doped iron oxide nanoparticles (Zn-IONPs), exhibit enhanced performance, broadening MPI's utility. Spatial encoding strategies, scanning trajectories, and instrumentation innovations are elucidated, illuminating the technical underpinnings of MPI's evolution. Moreover, integrating machine learning and deep learning methods enhances MPI's image processing capabilities, paving the way for more efficient segmentation, quantification, and reconstruction. The potential of superferromagnetic iron oxide nanoparticle chains (SFMIOs) as new MPI tracers further advanced the imaging quality and expanded clinical applications, underscoring the promising future of this emerging imaging modality.

Development and evaluation of the automated risk assessment system for multidrug-resistant organisms (autoRAS-MDRO).

BACKGROUND: A high proportion of infections acquired in hospitals are caused by multidrug-resistant organisms (MDROs). The priority in MDRO prevention is to detect high-risk patients and implement preventive intervention as soon as possible. AIM: To develop an automated risk assessment system for MDROs (autoRAS-MDRO) to screen for patients at MDRO infection risk and evaluate the predictive validity of the autoRAS-MDRO. METHODS: Data for 4200 variables were extracted from the electronic health records (EHRs) for constructing the MDRO risk-scoring algorithm, which was based on a logistic regression model. The autoRAS-MDRO was designed such that the MDRO risk classification (high, moderate, low risk) could be automatically displayed on the nursing Kardex screen in the EHRs system. For the development of the MDRO risk-scoring algorithm, 1000 patients with MDROs and 4000 patients without MDROs were selected; similarly, for the evaluation, 2173 and 8692 patients with and without MDROs, respectively, were selected. FINDINGS: The predictive validity of the autoRAS-MDRO was as follows: (i) at the 6-month evaluation: sensitivity, 81%; specificity, 79%; positive predictive value (PPV), 49%; negative predictive value (NPV), 94%; and Youden index, 0.60; (ii) at the 12-month evaluation: sensitivity 79%, specificity 78%, PPV 47%, NPV 94%, and Youden index, 0.57. CONCLUSION: The autoRAS-MDRO had moderate predictive validity. It could be useful in redirecting nurses' time and efforts required for MDRO risk assessment and implementation of infection control measures, and in reducing the incidence of MDRO infection in hospitals, thereby contributing to patient safety.

An outbreak of norovirus infection associated with fermented oyster consumption in South Korea, 2013.

An acute gastroenteritis (AGE) outbreak was reported in May 2013 in Gyeonggi Province, South Korea. Eight students who had eaten breakfast on 21 May 2013 at a high-school restaurant exhibited AGE symptoms. Our case-control study showed that a strong association was observed between AGE symptoms and fermented oyster consumption. Virological studies also indicated that noroviruses (NoVs) were detected from both clinical samples and fermented oyster samples, and multiple different genotypes (genogroups GII.4, GII.11 and GII.14) of NoVs were present in both samples. The nucleotide sequence similarity between the strains found in the clinical samples and those in the fermented oysters was more than 99·5%. Therefore, to prevent further outbreaks, proper management of raw oysters is necessary and the food industry should be aware of the risk of viral gastroenteritis posed by fermented oysters contaminated with NoVs.

Influence of single hemodialysis session on serum paraoxonase-1, arylesterase activity, total oxidant status and total antioxidant status.

AIM: Chronic kidney disease(CKD) and hemodialysis (HD) are associated with increased oxidative stress. Cardiovascular diseases (CVD) are the most important cause of mortality in these patients. Increased cardiovascular risk is associated with oxidative stress. The aim of this study was to evaluate whether the duration of single session hemodialysis may affect oxidative stress parameters on the patients with end-stage renal disease (ESRD). METHODS: Total oxidant status (TOS) and oxidative stress index (OSI) as oxidative markers and total antioxidant status (TAOS), paraoxonase1 (PON1) and arylesterase (ARES) as antioxidant markers were compared hemodialysis therapy before and after the treatment. RESULTS: TOS levels before hemodialysis were found as 4.4±2.4 µmol H2O2 Equiv/L, TAOS 2.1±0.3 µmol trolox Equiv./L, OSI 0.2±0.1%, PON1 levels 58.5±35.6 U/L and ARES levels 22±0.2 U/L while after the HD the respective values were 1.4±1.2 µmol H2O2 Equiv/L, 1.4±0.5 µmol trolox Equiv./L, 0.1±0.1%, 54.3±31.3 U/L, 21.8±0.1 U/L. A significant decreasing was observed in TOS TAOS OSI and ARES values before the HD compared to after the HD (P=0.0001, P=0.0001, P=0.0001, P=0.031, respectively). CONCLUSION: This study shows oxidant (TOS, OSI) and antioxidant (TAOS, ARES) markers were found to be significantly decrease after the HD compared to pre-hemodialysis. Although reverse is expected it is found that oxidants (indirectly ROS) did not increase and antioxidant reserve decreased in HD.

Glomerular filtration rate: which method should we measure in daily clinical practice?

AIM: In this study, we compared estimated glomerular filtration rate (eGFR) calculated with the formulas of Cockcroft-Gault (C&G), Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Mayo Clinic Quadratic (Mayo Q) and, GFR (mGFR) that was scintigraphically measured with creatinine clearance (CrCl) and technetium-99m diethylene triamine penta-acetic acid (99mTc-DTPA). Objective of this study was to define the correlations between the formulas, provide a reliable method for measurement and estimation of GFR in daily clinical practice and demonstrate the potential errors. METHODS: C&G, CKD-EPI, Mayo Q and MDRD eGFR of 84(37 males, 47 females) patients diagnosed with chronic kidney disease were calculated. Values of 99mTc-DTPA based on mGFR were compared with eGFR values of the formulas. RESULTS: Significant correlations were found with the values of 99mTc-DTPA mGFR, CrCl, MDRD, CKD-EPI, Mayo Q and C&G eGFR. The highest correlation was found between LBM(lean body mass) corrected C&G, MDRD-6, Mayo Q and CKD-EPI eGFR. The best estimate was made with MDRD-6 in the cases with 99mTc-DTPA mGFR<30 mL/min/1.73 m(2) and with MDRD-4 in the cases with 99mTc-DTPA mGFR≥30 mL/min/1.73 m(2), while the worst estimate was made with uncorrected C&G formula in both groups. CONCLUSION: All eGFR formulas can be used in daily clinical practice. However, using MDRD-6 in the cases with GFR<30 mL/min/1.73 m(2) and MDRD-4 in the cases with GFR≥30 mL/min/1.73m(2) as well as using LBM for C&G eGFR or correction according to LBM when AW (actual weight) is used, might provide a more accurate estimation.

Recovery process in patients followed-up due to acute kidney injury.

INTRODUCTION: Acute kidney injury (AKI) may result in complete recovery in some of the patients and partial recovery in others. AKI episodes may accelerate the progression to chronic kidney disease and end-stage renal failure, while risk for morbidity and mortality is high following AKI. Discharge of patients from the hospital, independently from dialysis is a crucial outcome. Many patients without a need for dialysis, require follow-up for various durations and different treatments. The objective of this study was to compare mean recovery time of the patients followed-up due to prerenal, renal and postrenal AKIs. METHOD: In this prospective observational study, a total of 159 patients hospitalized in Bulent Ecevit Hospital, clinic of nephrology or monitored in the other wards and intensive care unit due to AKI, between June 2011 and January 2012, were enrolled. The cases were divided into three groups as prerenal, renal and postrenal, and monitored with the daily visits and renal function testing. RESULTS: Prerenal AKI was seen by 54%, while renal AKI was observed by 34% and post-renal AKI by 12%. Incidence of chronic kidney disease was 17.6%. Totally 43 patients required hemodialysis (27%). Of these patients, 23 were in the prerenal AKI (53.4%), 15 in the renal AKI (34.8%) and 5 (11.6%) in the postrenal AKI group. Blood urea nitrogen (BUN) and creatinine levels were dropped to the basal values only in the prerenal AKI group, on the seventh day of treatment. These levels remained higher in the postrenal and renal groups on the 7th day of treatment compared to the basal values. BUN levels decreased to the normal values on average 7th day in the postrenal, while remained higher in the renal group. CONCLUSION: Prerenal AKI patients recovered in seven days with a proper treatment, although AKI patients due to other reasons should be followed-up for a longer time.

Trimethylaminuria (fish malodour syndrome) in chronic renal failure.

Trimethylaminuria (fish malodour syndrome) is a rare genetic metabolic disorder presented with a body odour which smells like a decaying fish. This odour is highly objectionable, that can be destructive for the social, and work life of the patient. Trimethylamine is derived from the intestinal bacterial degradation of foods that are rich of choline and carnitine. Trimethylamine is normally oxidised by the liver to odourless trimethylamine N-oxide which is excreted in the urine, so, uremia may worsen the condition. Uremia itself may cause more or less unpleasant odour. Poor uremic control may worsen the odour. We reported this case because Trimethylaminuria is not usually considered in the differential diagnosis of malodour in chronic renal failure and it is the first case that shown the association with Trimethylaminuria and chronic renal failure in the literature.

Non steroidal antiinflammatory drugs may be harmful to normal kidneys: experimental surgery model*.

BACKGROUND AND AIM: The exact effect of analgesics on normal kidneys is not known yet. We aimed to evaluate the impression of non steroidal antiinflammatory drugs (NSAID) used post-operatively on kidneys, in rat (tracheotomy) model. METHODS: Twenty-five non-uremic male wistar albino rats were included. For 18 rats, tracheotomy was performed and divided into two groups. First group, NSAID (diclofenac 10 mg/kg/day intramuscular (im)) (NSAID, n=8); second group isotonic (im)(Control, n=10) were administered for a week. For third group (Histological control,n=7) in order to evaluate normal histology neither surgery nor medication were applied. At the end (7th day), 24 hours urine collected then, blood samples were taken by intracardiac punction and were sacrified. One of the kidneys fixed for histological evaluation, the other was preserved for the measurements of tissue enzyme levels. Lipid peroxidation products and antioxidant enzyme levels were measured both from plasma and renal tissues. Histologically inflammation, regeneration, degeneration assessed semiquatitativelly and immunohistochemical dyes were applied. RESULTS: Hemoglobin thiobarbituric acid reactive substance level indicating the increase of lipid peroxidation in NSAID group was higher than control group (673±204 vs.373±27nmol/gHb respectively, p>0.05). Superoxide dismutase (one of the antioxidant enzymes responsible for reduction of reactive oxygen substances) and serum nitrate levels were lower in NSAID groups (700±68 vs.1371±164U/gHb and 26±4.4 vs.50.8±6.8 µmol/mL respectively, p<0.05).Although tissue levels were parallel to plasma levels but the difference wasn't significant. In histological assessment degeneration was present only in NSAID group (1.3±0.6 vs.0.0±0, p<0.05). Inflammation were lower than the control group (0.8±0.4 vs.1.2±0.2, p>0.05). Cyclooxygenase-2 expression was disappeared in NSAID group. CONCLUSIONS: NSAIDs mostly used post-operatively for analgesia, may cause unfavorable effects on kidneys by oxidative stress.

Bioimpedance and echocardiography used interchangeably in volume comparison of dialysis patients.

BACKGROUND: Euvolemia is a major issue in chronic kidney disease. The present study compares cardiac condition and volume status in peritoneal dialysis (PD) and hemodialysis (HD) patients and points out importance of volume control. METHODS: From a single-center center, 81 PD and 89 HD patients were enrolled. Echocardiography and body composition analysis using bioimpedance spectroscopy (BIS) technique were performed. Overhydration (OH) and extracellular water (ECW) in liters and OH/ECW % were used as volume indices. RESULTS: Patients were younger (47.6±14. 5 and 53.1±11.8 years, p< 0.05), daily urine volume higher (1068±926 vs 290±444 ml, p <0.001) and dialysis vintage was shorter (30.1±18.6 vs 53.6±35.4 months, p<0.001), systolic blood pressure was lower (127.5±15.4 vs 140.3±18.9 mmHg, p<0.001) in PD than HD group respectively. Volume indices were (OH, OH/ECW %, ECW/height, ECW to Intracellular Water ratios (E/I) (p<0.05)) significantly higher in HD patients compared to PD patients. Over all 66 of 170 patients (39%) had OH/ECW % <5 and OH/ECW % ratio was positively correlated with Left atrium index (R(2):0.105, p<0.05). Interventricular septum diameter and Left ventricular mass index (1.41±0.24 and 159.6±48.2 vs. 1.27±0.17 cm and 115.8±37 g/m(2), p<0.001) were increased in HD than in PD group. After multivariate adjustment OH/ECW increased with: HD and diabetic patients. LVH increased with: HD group, OH/ECW (%) and SBP significantly. CONCLUSION: Overhydration was more common among HD. Excess fluid may lead adverse effect in organ functions especially cardiac condition. This indicates that the current clinical and technical tools to achieve euvolemia are insufficient and that an additional tool, such as BIS, could be useful in the diagnosis of overhydration.

The effect of immunosuppressive treatment on arterial stiffness and matrix Gla protein levels in renal transplant recipients.

INTRODUCTION: Arterial stiffness is a risk marker for cardiovascular events. In this study we aimed to compare the effect on calcineurin inhibitors (CNI) and mammalian Target of Rapamycine inhibitors (mTORi) on arterial stiffness in renal transplant patients. PATIENTS AND METHODS: 81 renal transplant patients under CNI-based or mTORi-based protocol for at least 6 months were included in the study. Arterial stiffness was measured by using the SphygmoCor device (AtCor Medical, Sydney, Australia). Vitamin K-dependent, calcification inhibitor matrix Gla protein (MGP) concentrations were quantified by ELISA methods (Biomedica, Vienna, Austria). RESULTS: 34 patients were on mTORi-based and 47 on CNI-based immunosuppression. Mean age was 37.9 ± 10.8 (18 - 71) years and 45% were female. Age, gender, graft functions and follow-up period of the groups were similar. Augmentation index was 15.2 ± 12.6% in CNI and 18.8 ± 14.0% in mTORi groups (p > 0.05). There was no difference regarding carotid-femoral pulse wave velocity between groups. Arterial stiffness was positively correlated with age, total cholesterol, LDL cholesterol, mean arterial pressure (MAP) and proteinuria. MGP levels were higher in the mTORi group but were not predictors for carotid-femoral pulse wave velocity. CONCLUSION: Rather than specific immunosuppressive drug effects, conventional risk factors, blood pressure and proteinuria are the most important predictors for arterial stiffness in renal transplant patients.

Vesicular glutamate transporter 1 and vesicular glutamate transporter 2 synapses on cholinergic neurons in the sublenticular gray of the rat basal forebrain: a double-label electron microscopic study.

The basal forebrain (BF) comprises morphologically and functionally heterogeneous cell populations, including cholinergic and non-cholinergic corticopetal neurons that are implicated in sleep-wake modulation, learning, memory and attention. Several studies suggest that glutamate may be among inputs affecting cholinergic corticopetal neurons but such inputs have not been demonstrated unequivocally. We examined glutamatergic axon terminals in the sublenticular substantia innominata in rats using double-immunolabeling for vesicular glutamate transporters (Vglut1 and Vglut2) and choline acetyltransferase (ChAT) at the electron microscopic level. In a total surface area of 30,000 microm(2), we classified the pre- and postsynaptic elements of 813 synaptic boutons. Vglut1 and Vglut2 boutons synapsed with cholinergic dendrites, and occasionally Vglut2 axon terminals also synapsed with cholinergic cell bodies. Vglut1 terminals formed synapses with unlabeled dendrites and spines with equal frequency, while Vglut2 boutons were mainly in synaptic contact with unlabeled dendritic shafts and occasionally with unlabeled spines. In general, Vglut1 boutons contacted more distal dendritic compartments than Vglut2 boutons. About 21% of all synaptic boutons (n=347) detected in tissue that was stained for Vglut1 and ChAT were positive for Vglut1, and 14% of the Vglut1 synapses were made on cholinergic profiles. From separate cases stained for Vglut2 and ChAT, 35% of all synaptic boutons (n=466) were positive for Vglut2, and 23% of the Vglut2 synapses were made on cholinergic profiles. On average, Vglut1 boutons were significantly smaller than Vglut2 synaptic boutons. The Vglut2 boutons that synapsed cholinergic profiles tended to be larger than the Vglut2 boutons that contacted unlabeled, non-cholinergic postsynaptic profiles. The presence of two different subtypes of Vgluts, the size differences of the Vglut synaptic boutons, and their preference for different postsynaptic targets suggest that the action of glutamate on BF neurons is complex and may arise from multiple afferent sources.

Mitogen-activated protein kinase kinase inhibitor PD98059 blocks the trans-activation but not the stabilization or DNA binding ability of hypoxia-inducible factor-1alpha.

Under low oxygen tension, cells increase the transcription of specific genes that are involved in angiogenesis, erythropoiesis, and glycolysis. Hypoxia-induced gene expression primarily depends on the stabilization of the alpha-subunit of hypoxia-inducible factor-1 (HIF-1alpha), which acts as a heterodimeric trans-activator. Our results indicate that stabilization of HIF-1alpha protein by treatment of proteasome inhibitors, is not sufficient for hypoxia-induced gene activation, and an additional hypoxia-dependent modification is necessary for gene expression by HIF-1alpha. Here, we demonstrate that mitogen-activated protein kinase kinase-1 (MEK-1) inhibitor PD98059 does not change either the stabilization or DNA binding ability of HIF-1alpha but it inhibits the trans-activation ability of HIF-1alpha, thereby it reduces the hypoxia-induced transcription of both an endogenous target gene and a hypoxia-responsive reporter gene. We found that hypoxia induced p42/p44 mitogen-activated protein kinases (MAPKs) that are target protein kinases of MEK-1, and that expression of dominant-negative p42 and p44 MAPK mutants reduced HIF-1-dependent transcription of the hypoxia-responsive reporter gene. Our results are the first to identify that hypoxia-induced trans-activation ability of HIF-1alpha is regulated by different mechanisms than its stabilization and DNA binding, and that these processes can be experimentally dissociated. MEK-1/p42/p44 MAPK regulates the trans-activation, but not the stabilization or DNA binding ability, of HIF-1alpha.

Coupling of L-type voltage-sensitive calcium channels to P2X(2) purinoceptors in PC-12 cells.

Extracellular ATP elevates cytosolic Ca(2+) by activating P2X and P2Y purinoceptors and voltage-sensitive Ca(2+) channels (VCCCs) in PC-12 cells, thereby facilitating catecholamine secretion. We investigated the mechanism by which ATP activates VSCCs. 2-Methylthioadenosine 5'-triphosphate (2-MeS-ATP) and UTP were used as preferential activators of P2X and P2Y, respectively. Nifedipine inhibited the ATP- and 2-MeS-ATP-evoked cytosolic Ca(2+) concentration increase and [(3)H]norepinephrine secretion, but not the UTP-evoked responses. Studies with Ca(2+) channel blockers indicated that L-type VSCCs were activated after the P2X activation. Mn(2+) entry profiles and studies with thapsigargin revealed that Ca(2+) entry, rather than Ca(2+) release, was sensitive to nifedipine. Although P2X(2) and P2X(4) receptor mRNAs were detected, studies with pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid revealed that P2X(2) was mainly coupled to the L-type VSCCs. The inhibitory effect of nifedipine did not occur in the absence of extracellular Na(+), suggesting that Na(+) influx, which induces depolarization, was essential for the P2X(2)-mediated activation of VSCCs. We report that depolarization induced by Na(+) entry through the P2X(2) purinoceptors effectively activates L-type VSCCs in PC-12 cells.

The crystal structure of the GCY1 protein from S. cerevisiae suggests a divergent aldo-keto reductase catalytic mechanism.

The crystal structure of the GCY1 gene product from Saccharomyces cerevisiae has been determined to 2.5 A and is being refined. The model includes two protein molecules, one apo and one holo, per asymmetric unit. Examination of the model reveals that the active site surface is somewhat flat when compared with the other aldo-keto reductase structures, possibly accommodating larger substrates. The K(m) for NADPH (28.5 microM) is higher than that seen for other family members. This can be explained structurally by the lack of the 'safety belt' of residues seen in other aldo-keto reductases with higher affinity for NADPH. Catalysis also differs from the other aldo-keto reductases. The tyrosine that acts as an acid in the reduction reaction is flipped out of the catalytic pocket. This implies that the protein must either undergo a conformational change before catalysis can take place or that there is an alternate acid moiety.

Efforts in minimizing risk of viral transmission through viral inactivation.

The viral safety of blood and blood products has improved substantially over the last decade on account of the development of new viral screening and virucidal procedures. For nearly 15 years, virally inactivated blood derivatives, prepared by using advanced virucidal procedures, have amassed an extraordinary safety record with respect to hepatitis B and C and HIV. This record of safety has spawned the development of newer virucidal procedures designed to eliminate nonenveloped viruses from blood derivatives and viruses and other pathogens from blood components, including cellular components. Ongoing tests that include clinical studies will demonstrate how close we are to achieving a blood supply that is free of viruses, bacteria, and parasites.

Photochemical decontamination of red blood cell concentrates with the silicon phthalocyanine PC 4 and red light.

Various approaches are being developed for virus inactivation of red blood cell concentrates (RBCC) in order to increase the safety of the blood supply. We have been studying the silicon phthalocyanine Pc 4 for this purpose, a photosensitizer activated with red light. Pc 4 targets the envelope of pathogenic viruses such as HIV. To protect RBC during the process two main approaches are used: (i) inclusion of quenchers of reactive oxygen species produced during the treatment. Tocopherol succinate was found to be most effective for this purpose; (ii) formulation of Pc 4, a lipophilic compound, in liposomes that reduce its binding to RBC but not to viruses. As a light source we used a light emitting diode array emitting at 670-680 nm. An efficient mixing device ensures homogenous light exposure during treatment of intact RBCC. Treatment of 50 ml RBCC with 5 microM Pc 4 and 18 J/cm(2) light results in the inactivation of > or = 5.5 log(10) HIV, > or = 6.3 log(10), VSV and > or = 5 log(10) of PRV and BVDV. The relative sensitivities of these viruses based on the slope of virus kill versus light dose are 1.0, 1.25, 1.5 and 1.9 for HIV, VSV, PRV and BVDV, respectively. To achieve the same level of virus inactivation in 350 ml RBCC, the light dose needed is 40 J/cm(2). HIV actively replicating in CEM cells is as sensitive as cell-free and HIV in latently infected cells is 3-4 times more sensitive. Parasites that can be transmitted by blood transfusion (P. falciparum and T. cruzi) are even more sensitive than viruses. Following treatment, RBCC can be stored for 28 days at 4 degrees C with haemolysis below 1%. Previous studies under less favourable conditions showed that baboon RBC circulated with an acceptable 24 hr recovery and half-life. Genetic toxicological studies of Pc 4 with or without light exposure (mutagenicity in bacteria, mammalian cells in vitro and clastogenicity in vivo) were negative. We conclude that a process using Pc 4 and red light can potentially reduce the risk of transmitting pathogens in RBCC.

Crystallization and aldo-keto reductase activity of Gcy1p from Saccharomyces cerevisiae.

Crystallization and preliminary X-ray diffraction studies of Gcy1p, an aldo-keto reductase from Saccharomyces cerevisiae, have been performed. Both the wild type and a double-mutant form of Gcy1p were crystallized using the hanging-drop method at 298 K; however, only the double-mutant form has so far yielded crystals suitable for X-ray diffraction analysis. These crystals belonged to the primitive monoclinic space group P2(1), with unit-cell parameters a = 50.94, b = 65.64, c = 86.23 A, beta = 92.64 degrees. Diffraction data were collected to 2.5 A. Assuming two 35 kDa subunits in the asymmetric unit yielded a V(m) of 2.06 A(3) Da(-1). Additionally, a kinetic study performed by measuring the rate of oxidation of NADPH in the presence of several substrates indicates that both wild-type and double-mutant proteins are enzymes possessing NADPH-dependent reductase activity.

Nongenomic inhibition of catecholamine secretion by 17beta-estradiol in PC12 cells.

We investigated the effects of 17beta-estradiol, an estrogen, on [(3)H]norepinephrine ([(3)H]NE) secretion in PC12 cells. Pretreatment with 17beta-estradiol reduced 70 mM K(+)-induced [(3)H]NE secretion in a concentration-dependent manner with a half-maximal inhibitory concentration (IC(50)) of 2 +/- 1 microM. The 70 mM K(+)-induced cytosolic free Ca(2+) concentration ([Ca(2+)](i)) rise was also reduced when the cells were treated with 17beta-estradiol (IC(50) = 15 +/- 2 microM). Studies with voltage-sensitive calcium channel (VSCC) antagonists such as nifedipine and omega-conotoxin GVIA revealed that both L- and N-type VSCCs were affected by 17beta-estradiol treatment. The 17beta-estradiol effect was not changed by pretreatment of the cells with actinomycin D and cycloheximide for 5 h. In addition, treatment with pertussis or cholera toxin did not affect the inhibitory effect of 17beta-estradiol. 17beta-Estradiol also inhibited the ATP-induced [(3)H]NE secretion and [Ca(2+)](i) rise. In PC12 cells, the ATP-induced [Ca(2+)](i) rise is known to occur through P2X(2) receptors, the P2Y(2)-mediated phospholipase C (PLC) pathway, and VSCCs. 17beta-Estradiol pretreatment during complete inhibition of the PLC pathway and VSCCs inhibited the ATP-induced [Ca(2+)](i) rise. Our results suggest that 17beta-estradiol inhibits catecholamine secretion by inhibiting L- and N-type Ca(2+) channels and P2X(2) receptors in a nongenomic manner.

Photochemical decontamination of red cell concentrates with the silicon phthalocyanine pc 4 and red light.

Virus inactivation in red blood cell concentrates (RBCC) is being studied in order to increase the safety of the blood supply. For this purpose we have been studying the silicon phthalocyanine (Pc 4), a photosensitizer activated with red light. Two approaches were used to achieve enhanced selectivity of Pc 4 for virus inactivation. One was formulation of Pc 4 in liposomes that reduce its binding to red cells. The other was the use of a light emitting diode (LED) array emitting at 700 nm. Vesicular stomatitis virus (VSV) infectivity served as an endpoint for virus kill in treated RBCC. Red cell hemolysis and circulatory survival in rabbits served as measures for red cell damage. Treatment of small aliquots of human RBCC with 2 µM Pc 4 in liposomes and 10 J/cm2 of 700 nm LED light in the presence of the quenchers of reactive oxygen species glutathione and trolox resulted in 6 log10 inactivation of VSV. Under these conditions hemolysis of treated red cells stored at 4 °C for 21 days was only slightly above that of control cells. Rabbit RBCC similarly treated circulated with a half life of 7.5 days compared with 10.5 days of control. It is concluded that Pc 4 used as described here may be useful for viral decontamination of RBCC, pending toxicological and clinical studies. © 1999 Society of Photo-Optical Instrumentation Engineers.