Hypoxic BMSC-derived exosomal miR-652-3p promotes proliferation and metastasis of hepatocarcinoma cancer cells via targeting TNRC6A

Cancer microenvironment plays an important role in the proliferation and metastasis of hepatocarcinoma cancer cells (HCC). Exosomes from bone marrow-derived mesenchymal stem cells (BMSCs) are a component of the cancer microenvironment. In this study, we reveal that miRNA-652-3P from BMSC-derived exosomes promotes proliferation and metastasis in HCC. The ability of cancer proliferation, migration and invasion can be evaluated after co-culture by CCK-8, wound healing and transwell assay. Isolated exosomes were identified by transmission electron microscopy (TEM) and the biomarkers of the purified exosomes were showed in West-blotting (WB). MiR-652-3p was detected in the HepG2 and 7721 after co-culturing with exosome derived from BMSCs under different conditions. Target authentication was performed by a luciferase reporter assay to confirm the presumptive target of miR-652-3p. After overexpressing miR-652-3p, the mRNA and protein expression level of TNRC6A in HCC was examined by q-PCR and WB. Further, we observed greater miR-652-3p upregulation in hypoxic BMSCs-exosomes than in normal- exosomes. In addition, a miR-652-3p inhibitor attenuates the proliferation and metastasis of HCC cells after co-culturing with BMSCs. Our data demonstrate that hypoxic BMSCs-derived exosomal miR-652-3p promotes proliferation in HCC cells by inhibiting TNRC6A. The BMSCs-derived exosomal miR-652-3p may help find patient-targeted therapies in hepatocarcinoma cancer.

Eucommia Bark/Leaf Extract Improves Lipid Metabolism Disorders by Affecting Intestinal Microbiota and Microbiome-Host Interaction in HFD Mice

Eucommia bark contains many bioactive compounds and has anti-hyperlipidemic effects. However, due to the slow growth rate of the plant, there is a limited supply of this resource. Studies have demonstrated that Eucommia leaves contain active ingredients similar to those of Eucommia bark and also have anti-hyperlipidemic effects. It is not currently clear whether Eucommia leaf can be used as a substitute for Eucommia bark. Furthermore, their mechanism of action for anti-hyperlipidemia by improving the structure of the gut microbiota is also unclear. We aimed to determine the composition of the active ingredients in EBE and ELE by HPLC, establish an HFD-induced hyperlipidemia model, and combine fecal microbiota transplantation (FMT) experiments to investigate the mechanism of EBE/ELE anti-hyperlipidemia by modifying the structure of intestinal microbiota, as well as to compare the effects of EBE and ELE. Our results showed that EBE and ELE contained similar active ingredients and significantly alleviated lipid metabolism disorders and blood glucose levels in the HFD-induced hyperlipidemia model. In this study, EBE and ELE significantly reduced the relative abundance of Desulfovibrionaceae and Erysipelotrichaceae and significantly increased the relative abundance of Ruminococcaceae. They also promoted the production of short-chain fatty acids (SCFAs) and activated the gene expression of the SCFA receptors G protein-coupled receptor 41 (GPR41) and GPR43. In addition, EBE and ELE can significantly increase the expression of the fasting-induced adipose factor (Fiaf) gene in the colon and inhibit the secretion of lipoprotein lipase (LPL) in the liver, thereby inhibiting triglyceride (TG) synthesis. They also significantly activate the expression of GPR41 and GPR43 genes in the epididymal fat tissue, leading to reduced lipid accumulation in adipocytes. These effects on the target genes were associated with changes in the abundance of Desulfovibrionaceae, Erysipelotrichaceae, and Ruminococcaceae bacteria in the intestinal microbiota. Thus, regulating the relative abundance of these microbes may serve as prospective targets for EBE/ELE to influence the Fiaf-LPL gut-liver axis and the SCFAs-GPR41/GPR43 gut-fat axis. In addition, there was no significant difference in the anti-hyperlipidemic effects of ELE and EBE, suggesting that Eucommia leaf may be a suitable alternative to Eucommia bark for managing hyperlipidemia by regulating the structure of the intestinal microbiota. These findings suggest that Eucommia leaves have great potential for development as a functional food with lipid-lowering properties.

Eucommia bark/leaf extract improves HFD-induced lipid metabolism disorders via targeting gut microbiota to activate the Fiaf-LPL gut-liver axis and SCFAs-GPR43 gut-fat axis

BACKGROUND

The bark of Eucommia ulmoides (a perennial deciduous tree termed eucommia hereafter) has anti-hyperlipidemia effects due to its bioactive components. However, the slow growth of eucommia bark leads to a deficit in this resource. Studies have shown that eucommia leaf has bioactive components similar to those of eucommia bark and anti-hyperlipidemia effects. At present, the strength of the anti-hyperlipidemia effect of eucommia bark and eucommia leaf has not been reported. Their interaction with the gut microbiota and the mechanism by which the gut microbiota exerts anti-hyperlipidemia effects are unclear.

PURPOSES

Through fecal microbiota transplantation (FMT) experiments, this study aimed to investigate the mechanism by which fecal bacteria suspensions containing chlorogenic acid (CGA), eucommia bark extract (EBE), and eucommia leaves extract (ELE) improve high-fat diet (HFD)-induced lipid metabolism disorders. Difference in anti-hyperlipidemia effects between EBE and ELE and exploring an eucommia bark substitute to improve the sustainable utilization of eucommia were also evaluated.

RESULTS

EBE and ELE contain eight identical bioactive ingredients, and fecal bacteria suspensions containing EBE and ELE significantly improved HFD-induced lipid metabolism disorders and elevated blood glucose levels. The fecal bacteria suspension of healthy mice containing CGA, EBE, and ELE significantly reduced the relative abundance of Erysipelothrichaceae and Ruminococcaceae and promoted short chain fatty acids (SCFAs) production thereby activating the expression of the SCFA. G protein-coupled receptor 43 (GPR43) gene in colon and epididymal fat tissues. In addition, fecal bacteria suspensions of healthy mice containing CGA, EBE, or ELE significantly activated fasting-induced adipose factor (Fiaf) gene expression in colon tissue and inhibited the secretion of lipoprotein lipase (LPL) in liver tissue, thereby inhibiting the synthesis of triglycerides (TG). Changed in the Erysipelotrichaceae and Ruminococcaceae relative abundances were significantly correlated with these target genes. Thus, regulating the abundance of the Erysipelotrichaceae and Ruminococcaceae could serve as a potential target for the role of fecal bacteria suspensions of healthy mice containing CGA, EBE, or ELE in the Fiaf-LPL gut-liver axis and SCFAs-GPR43 gut-fat axis. In addition, regarding HFD-induced lipid metabolism disorders and gut microbiota structural disorders, we found no significant difference between ELE and EBE.

CONCLUSIONS

Our FMT experiments evidenced that EBE and ELE improve lipid metabolism disorders by regulating the gut microbiota, providing a new pathway for treating hyperlipidemia using eucommia dietary therapy. There was no significant difference in the anti-hyperlipidemia effects of ELE and EBE; thus, eucommia leaf could replace eucommia bark in traditional Chinese medicine, so as to achieve a sustainable utilization of eucommia resources.

miR-205 Reverses MDR-1 Mediated Doxorubicin Resistance via PTEN in Human Liver Cancer HepG2 Cells

Objective

The aim of the recent study was to investigate the effects of miR-205 on reversing Doxorubicin (DOX) resistance, as chemotherapeutic agents through up-regulation of PTEN in human liver cancer HepG2 cells.

Materials and Methods

In this experimental study, the drug resistance in liver cancer cells via drug efflux inhibition and enhancing apoptosis by the regulation of PTEN and multi-drug resistance/ P-glycoprotein (MDR/P-gp) expression was revealed. Using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, effect of DOX on cell proliferation was evaluated after miR-205 transfection in HepG2 and HepG2/DOX cells. Activity of P-gp on drug efflux was measured by the Rhodamine 123 (Rho-123) assay. PTEN mRNA expression levels were measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and flow cytometry was used to measure the apoptotic ratio of HepG2/DOX cells.

Results

miR-205 overexpression considerably inhibited the HepG2/DOX cells viability (P<0.05). qRT-PCR results revealed that PTEN is a pivotal regulator in PI3K/Akt/P-gp axis. Overexpression miR-205 resulted in up-regulation PTEN and ultimately down-regulation of P-gp. This inhibits drug resistance, proliferation and induces apoptosis in HepG2/DOX cells (P<0.05). Whilst, treatment with 10 μM of special inhibitors, including LY294002 (PI3K) or PD098059 (MAPK), increased Rho 123-associated MFI, treatment with 10 μM of SF1670 (PTEN) almost abolished the effect of miR-205 overexpression (P<0.05). Finally, we found that miR-205 was down-regulated in HepG2/DOX cells, and its overexpression led to enhancing apoptosis with re-sensitization of HepG2/DOX cell lines to DOX through PTEN/PI3K/ Akt/MDR1 pathway.

Conclusion

These findings may introduce miR-205 as a predictive biomarker and a potential treatment target for liver cancer therapy during MDR.

Primary lateral sclerosis: A heterogeneous disorder composed of different subtypes?

OBJECTIVE

To determine identifiable subgroups of patients with primary lateral sclerosis (PLS) with distinct clinical features as a first step in identifying patients likely to have the same disorder.

METHODS

Twenty-five patients meeting previously proposed diagnostic criteria for PLS were seen for examination, measurement of gait and finger tapping speed, and physiologic tests to assess motor pathways. Motor cortex excitability and central motor conduction time were assessed with transcranial magnetic stimulation. Brainstem motor pathways were assessed by the acoustic startle reflex. MRS was performed in a subgroup of patients to assess metabolites in the motor cortex.

RESULTS

Fifty-six percent of the patients with PLS had a similar pattern of symptom progression, which the authors termed ascending. In these patients spasticity began in the legs and progressed slowly and steadily. Spasticity in the arms developed 3.6 years after the legs, on average, and speech impairment followed 1.5 years later. Motor evoked potentials were absent. MRS showed a mean reduction of N-acetylaspartate/creatinine in the motor cortex. The remaining patients with PLS had heterogeneous patterns of symptom progression and physiology.

CONCLUSIONS

Patients with PLS with an ascending progression of symptoms form a distinct clinical subgroup that may be amenable to investigations of etiology and treatment.

Effects of deletion of streptokinase residues 48-59 on plasminogen activation

Streptokinase (SK) is a thrombolytic agent widely used for the clinical treatment of clotting disorders such as heart attack. The treatment is based on the ability of SK to bind plasminogen (Pg) or plasmin (Pm), forming complexes that proteolytically activate other Pg molecules to Pm, which carries out fibrinolysis. SK contains three major domains. The N-terminal domain, SKalpha, provides the complex with substrate recognition towards Pg. SKalpha contains a unique mobile loop, residues 45-70, absent in the corresponding domains of other bacterial Pg activators. To study the roles of this loop, we deleted 12 residues in this loop in both full-length SK and the SKalpha fragment. Kinetic data indicate that this loop participates in the recognition of substrate Pg, but does not function in the active site formation in the activator complex. Two crystal structures of the deletion mutant of SKalpha (SKalpha(delta)) complexed with the protease domain of Pg were determined. While the structure of SKalpha(delta) is essentially the same as this domain in full-length SK, the mode of SK-Pg interaction was however different from a previously observed structure. Even though mutagenesis studies indicated that the current complex represents a minor interacting form in solution, the binding to SKalpha(delta) triggered similar conformational changes in the Pg active site in both crystal forms.

Effects of dietary phytoestrogen on global myocardial ischemia-reperfusion injury in isolated female rat hearts

We investigated the effects of phytoestrogen on global myocardial ischemia-reperfusion injury in five groups of female rats. A high-phytoestrogen group (HPE) was ovariectomized (Ovx) and fed a diet containing soybean protein and a high-isoflavone soy extract. Another Ovx group of rats was fed the same diet as the HPE group but treated with the estrogen receptor blocker ICI-182,780 (HPE + ICI). A third group of Ovx rats was fed a diet containing soybean protein alone (low-phytoestrogen content; LPE). A fourth Ovx group was fed a diet free of phytoestrogen (Ovx). The fifth group of rats was sham ovariectomized (sham). Hearts from all rats were subjected to 30 min of global, hypothermic (4 degrees C), cardioplegic ischemia and 120 min of normothermic (37 degrees C) reperfusion with oxygenated Krebs-Henseleit buffer. Compared with either the sham or the HPE group, the Ovx and HPE + ICI groups had significantly decreased first derivative of left ventricular pressure (dP/dt), coronary flow rate (CFR), nitrite production and mitochondrial respiratory function and significantly increased Ca2+ accumulation and myocardial histological and ultrastructural injury. The CFR of the LPE group was significantly different from that of either Ovx or HPE + ICI group but the dP/dt, nitrite production, Ca2+ accumulation, and mitochondrial function were not. Our results indicate that diets containing phytoestrogen extract play a cardioprotective role in global myocardial ischemia-reperfusion in female rats.

Regional characteristics of sulfur and lead isotope ratios in the atmosphere at several Chinese urban sites

Sulfur and lead isotope ratios in the atmosphere were measured at several selected sites (Harbin, Changchun, Dalian, Waliguan, Shanghai, Nanjing, Guiyang) in China and Tsukuba (Japan), to reveal regional sources characteristics over Eastern Asia. Average S isotope ratios for SO2 and sulfate in the atmosphere in China were close to those of the coals used in each region, indicating a considerable contribution of coal combustion to the sulfur compounds in the atmosphere. Most northern cities had around 5% sulfur isotope ratio, while Guiyang, a southwestern city in China, showed a considerably lower sulfur isotope ratio (about -3%) because of the unusually light sulfur isotope ratio of coals in this region. These were considerably different from the value (-1.4%) for Tsukuba (Japan). Lead isotope ratios also suggested that coal combustion considerably contributed to atmospheric lead in some cases in China. At the same time, influences by the emission of Chinese lead ores were also observed in northern cities. Seasonal variations of both sulfur and lead isotope ratios indicated the existence of a certain amount of industrial sources other than coal combustion. In addition, fractionation effect between SO2 and sulfate showed a seasonal tendency (high in winter (0-6%) and low in summer (-1-3%)), suggesting the oxidation pathway of SO2 changed seasonally.

Effect of estrogen on global myocardial ischemia-reperfusion injury in female rats

We investigated the effects of estrogen on global myocardial ischemia-reperfusion injury in rats that were ovariectomized (Ovx), sham-operated, or ovariectomized and then given 17beta-estradiol (E(2)beta) supplementation (Ovx+E(2)beta). Hearts were excised, cannulated, perfused with and then immersed in chilled (4 degrees C) cardioplegia solution for 30 min, and then retrogradely perfused with warm (37 degrees C), oxygenated Krebs-Henseleit bicarbonate buffer for 120 min. The coronary flow rate, first derivative of left ventricular pressure, and nitrite production were all significantly lower in Ovx than in sham-operated or Ovx+E(2)beta hearts. However, coronary flow rates or nitrate production were not consistently different throughout the entire reperfusion period. Ca(2+) accumulated more in Ovx rat hearts than in sham-operated or Ovx+E(2)beta hearts, and mitochondrial respiratory function was lower in Ovx hearts than in hearts from the other two groups. Marked interstitial edema and contraction bands were seen in hematoxylin-eosin-stained sections of Ovx rat hearts but not in hearts from either of the other groups. Hematoxylin-basic fuchsin-picric acid-stained sections revealed fewer viable myocytes in hearts from the Ovx group than from the sham or Ovx+E(2)beta group. Transmission electron microscopy demonstrated more severely damaged mitochondria and ultrastructural damage to myocytes in Ovx rat hearts. Our results indicate that estrogen plays a cardioprotective role in global myocardial ischemia-reperfusion injury in female rats.

Myocardial ischemia-reperfusion injury in estrogen receptor-alpha knockout and wild-type mice

We investigated the function of estrogen receptor-alpha in global myocardial ischemia and reperfusion injury in male estrogen receptor-alpha knockout (ERKO) and wild-type mice. Mouse hearts were subjected to 45 min of global ischemia followed by 180 min of reperfusion. The hearts were excised, cannulated, and maintained in a chilled (4 degrees C) cardioplegia solution until warm (37 degrees C) oxygenated Krebs-Henseleit bicarbonate buffer was perfused through the coronary arteries. ERKO hearts started beating later and had a higher incidence of ventricular fibrillation and/or tachycardia than control hearts. Coronary flow rate was significantly lower in ERKO hearts during the 90- and 120-min periods of reperfusion. Ca(2+) accumulation was significantly greater following 30, 90, 120, 150, and 180 min of reperfusion in ERKO hearts. Nitrite production was significantly less in ERKO hearts following 90, 120, and 150 min of reperfusion. Myocardial reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was significantly lower in experimental ERKO hearts. Marked interstitial edema and contraction bands were seen in hematoxylin-eosin-stained sections of ischemia-reperfused ERKO hearts but not in control tissues. Hematoxylin-basic fuchsin-picric acid-stained sections from experimental ERKO hearts had fewer viable myocytes compared with controls. Transmission electron microscopy revealed swollen and fragmented mitochondria with amorphous and granular bodies, loss of matrix, and rupture of cristae in experimental ERKO hearts. This is the first demonstration that estrogen receptor-alpha plays a cardioprotective role in ischemia-reperfusion injury in males.

Lack of involvement of neuronal nitric oxide synthase in the pathogenesis of a transgenic mouse model of familial amyotrophic lateral sclerosis

A subset of familial cases of amyotrophic lateral sclerosis are linked to missense mutations in copper/zinc superoxide dismutase type 1. Patients with missense mutations in copper/zinc superoxide dismutase type 1 develop a paralytic disease indistinguishable from sporadic amyotrophic lateral sclerosis through an unknown toxic gain of function. Nitric oxide reacts with the superoxide anion to form the strong oxidant, peroxynitrite, which participates in neuronal injury in a variety of model systems. Peroxynitrite is an alternate substrate for copper/zinc superoxide dismutase type 1, causing catalytic nitration of tyrosine residues in other proteins. Mutations in copper/zinc superoxide dismutase type 1 may disrupt the active site of the enzyme and permit greater access of peroxynitrite to copper, leading to increased nitration by peroxynitrite of critical cellular targets. To investigate whether neuronal-derived nitric oxide plays a role in the pathogenesis of familial amyotrophic lateral sclerosis, we examined the effects of three different nitric oxide synthase inhibitors: a non-selective nitric oxide synthase inhibitor, nitro-L-arginine methyl ester; a relatively selective inhibitor of neuronal nitric oxide synthase, 7-nitroindazole; and a novel highly selective neuronal nitric oxide synthase inhibitor, AR-R 17,477, in transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 (Gly-->Ala at position 93; G93A) containing a high transgene copy number and a low transgene copy number. AR-R 17,477, but not nitro-L-arginine methyl ester or 7-nitroindazole, significantly prolonged survival in both the high and low transgene transgenic mice. To determine whether neuronal nitric oxide synthase is involved in the pathogenesis resulting from the familial amyotrophic lateral sclerosis copper/zinc superoxide dismutase type 1 mutation, we produced mice with the copper/zinc superoxide dismutase type 1 mutation which lack the neuronal nitric oxide synthase gene. The transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 on neuronal nitric oxide synthase null background do not live significantly longer than transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1. Western blot analysis indicates the presence of two neuronal nitric oxide synthase-like immunoreactive bands in spinal cord homogenates of the neuronal nitric oxide synthase null mice, and residual neuronal nitric oxide synthase catalytic activity ( > 7%) is detected in the spinal cord of the transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 on neuronal nitric oxide synthase null background. This amount of residual activity probably does not account for lack of protection afforded by the disrupted neuronal nitric oxide synthase gene in the familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 mice. Immunological nitric oxide synthase is not detected in the copper/zinc superoxide dismutase type 1 mutant mice at several different ages, thus excluding immunological nitric oxide synthase as a contributor to the pathogenesis of familial amyotrophic lateral sclerosis. Levels of neuronal nitric oxide synthase as well as Ca2+-dependent nitric oxide synthase catalytic activity in the copper/zinc superoxide dismutase type 1 mutant mice do not differ from wild type mice. Endothelial nitric oxide synthase levels may be decreased in the copper/zinc superoxide dismutase type 1 mutant mice. Together, these results do not support a significant role for neuronal-derived nitric oxide in the pathogenesis of familial amyotrophic lateral sclerosis transgenic mice.

Thrombogenicity of polyethylene oxide-bonded Dacron sewing ring in a mechanical heart valve

BACKGROUND AND AIM OF THE STUDY

The aim of the study was to evaluate the effect of binding hydrophilic polyethylene oxide (PEO) onto Dacron fibers in the sewing ring of a mechanical heart valve (MHV), in terms of thrombogenicity of the prosthesis.

METHODS

The study was performed in blinded fashion. Six Yorkshire-cross pigs (bodyweight 35-45 kg) were implanted with MHVs, in the mitral annulus, with the PEO-treated sewing ring. An additional five pigs implanted with identical MHVs, but with untreated sewing rings, served as controls. PEO of chain-length 10,000 Da was grafted to Dacron fibers using gamma irradiation. PEO-bonded Dacron fibers (diameter 100 microns) were used to weave the sewing ring, which was then assembled on a titanium stent (OD 25 mm). Autologous platelets were labeled with 111In-tropolone and injected intravenously (850-1250 microCi per injection) into the pigs on removal from cardiopulmonary bypass (CPB). At 20-24 h after surgery, platelet thrombi adherent to MHV components, and shed emboli trapped in the brain, lung, heart, kidneys and other organs/connective tissues were imaged using a gamma camera. The animals were killed and the amounts of thrombi adherent to MHV components and organ-trapped emboli quantified using an ionization chamber and gamma counter.

RESULTS

There was no statistically significant difference in the adhesion of 111In-labeled platelets to either control sewing rings (0.08 +/- 0.06% dose) or PEO-treated rings (0.19 +/- 0.21% dose). The thrombogenicity of MHV components in both animal groups was in the ascending order: Dacron ring > Teflon pledgets > polypropylene sutures > titanium housing > pyrolytic carbon. The number of platelet-emboli trapped in the organs was not significantly different between the two groups.

CONCLUSIONS

Simple modifications may not reduce platelet thrombosis or wound-healing of the sewing ring in the acute phase, at which time several complex processes are activating and inactivating platelets and coagulant factors during CPB and implantation of MHVs.

Recombinant adenovirus is an appropriate vector for endocytotic protein trafficking studies in cultured neurons

Endocytosis of full-length beta-amyloid precursor protein (APP) from the plasma membrane contributes to beta-amyloid peptide (Abeta) secretion, and, hence, potentially contributes to the molecular pathogenesis of Alzheimer's disease. We recently have demonstrated that central neuronal APP is endocytosed in a common vesicular compartment with recycling synaptic vesicle integral membrane proteins, but is then sorted away from synaptic vesicles for retrograde transport to the neuronal soma. For this report, we explore whether recombinant adenovirus can be used to modulate APP expression in cultured central neurons to study APP processing by the endocytotic pathway in these cells. Using a replication-deficient recombinant adenovirus that expresses a lacZ reporter (Ad5/CMV-lacZ), we demonstrate high efficiency of transfection (30-35%) at low viral titer (10-20 MOI), with no significant neuronal toxicity or cytoarchitectural change. In addition, we demonstrate that infection with the control virus does not result in re-direction of endogenous neuronal APP from usual endocytotic pathways. We have prepared, using the same genomic background as the control virus, an adenoviral vector that expresses the neuronal isoform of human APP (Ad5/CMV-APP). Infection with Ad5/CMV-APP at 10-20 MOI results in significantly increased immunoreactivity for endocytosed APP with preservation of usual endocytotic trafficking. These results demonstrate that recombinant adenovirus at low titer is an appropriate and effective vector for protein trafficking/processing studies in cultured central neurons.

Successful prosthetic mitral valve implantation in pigs

Clotting mechanisms, the coagulation cascade, platelet function, and platelet-leukocyte-endothelial cell interactions are all very similar in humans and pigs. Because of these similarities, the authors concluded that the pig would be an ideal model for the study of thromboembolism resulting from prosthetic heart valves. To date, they have successfully recovered a total of 11 pigs (52.9 +/- 8.1 kg), 3 with bioprosthetic valves and 8 with mechanical valves, all in the mitral position (25 mm od). The normal presence of high numbers of pulmonary endothelial macrophages and other unique aspects of porcine cardiovascular and pulmonary function dictate somewhat different surgical protocols than those normally used for human patients and ruminant species. Some of these special procedures include 1) crystalloid prime without the use of plasma volume expanders, especially those with a starch base; 2) pharmacologic protection against arrhythmias (lidocaine, 4 mg/kg); 3) special attention to adequate hypothermic cardioprotection during the time of cross-clamp; 4) the use of shock doses of corticosteroid (prednisolone sodium succinate, 0.5 mg/kg) before removal of the aortic cross-clamp; and 5) positive inotropic support (dopamine, 0.008 mg/kg) while weaning from cardiopulmonary bypass. Gamma camera images of 111In tagged autologous platelets 24 hours after surgery show most thrombi located on the sewing ring with fewer on the pledgets and anchor sutures. The latter observations were confirmed by quantification of platelet deposition using a gamma counter.

A new method for quantitation of platelet microthrombi and microemboli from cardiopulmonary bypass in organs using 111In labeled platelets

During cardiopulmonary bypass (CPB), showers of microemboli (ME) distribute among the organs and connective tissues according to regional blood flow. Post CPB, ME were quantified by subtracting residual platelets (RP) in the organs of a group of unoperated control Yorkshire pigs (n = 6) from those of operated pigs. The RP level was minimized by heparinization (300 IU/kg) before death and exsanguination. The number of adherent microthrombi (MT) and ME from the oxygenator (OX), arterial filter (AF), and thoracotomy site were determined using 111In labeled autologous platelets (INPLT) (525-585 microCi administered 24 hr before CPB) in two CPB groups (ACT > 400 sec) of 12 pigs (30-35 kg). CPB was carried out at a flow of 2.5-3.5 L/min at 28 degrees C with a roller or a centrifugal pump, OX (Bentley Univox 1.8 m2), AF (0.25 m2), and cardiotomy reservoir (CR) (Bentley BR: 3,500), for 90 (n = 6) and 180 (CPB 180, n = 6) min. Six pigs underwent thoracotomy without CPB. L-Arginine was infused at a dose of 2 mg/ kg/min during CPB (n = 6). Flow cytometry was used to estimate the circulating ME in blood. MT and organ trapped ME were imaged with a gamma camera and measured with an ion chamber and a gamma counter. ME values (percent of injected INPLT dose) in six organs and four connective tissues were calculated for all five groups. INPLT distribution indicated a uniform distribution of low level platelet MT in the CR and AF. Circulating ME amounted to 2.5% of total platelets. In the CPB circuit, ME generation in AF was the rate-limiting step (n = 4 x 10(5)). Similar studies in organs and tissues suggested the presence of a uniform distribution of the total events of ME (n = 500 x 10(6)). ME increase in brain, lung, liver, and skeletal muscle following thoracotomy and CPB was significant. The low level of ME in ischemia sensitive organs also indicated the presence of a thrombolytic threshold for cumulative ME. ME disaggregation was activated at an early stage to prevent ischemic damage, specifically in the brain. Measurement of trapped ME provided a novel, reliable, and one step method of evaluation of thrombogenicity of a CPB device and drugs.

Benefit of vitamin E, riluzole, and gabapentin in a transgenic model of familial amyotrophic lateral sclerosis

Familial amyotrophic lateral sclerosis (FALS) has been linked in some families to dominant mutations of the SOD1 gene encoding Cu,Zn superoxide dismutase (Cu,ZnSOD). We have used a transgenic model of FALS based on expression of mutant human Cu,ZnSOD to explore the etiology and therapy of the genetic disease. Expression of mutant, but not wild-type, human Cu,ZnSOD in mice places the brain and spinal cord under oxidative stress. This causes depletion of vitamin E, rather than the typical age-dependent increase in vitamin E content as occurs in nontransgenic mice and in mice expressing wild-type human Cu,ZnSOD. Dietary supplementation with vitamin E delays onset of clinical disease and slows progression in the transgenic model but does not prolong survival. In contrast, two putative inhibitors of the glutamatergic system, riluzole and gabapentin, prolong survival. However, riluzole did not delay disease onset. Thus, there was clear separation of effects on onset, progression, and survival by the three therapeutics tested. This suggests the hypothesis that oxidative damage produced by the expression of mutant Cu,ZnSOD causes slow or weak excitotoxicity that can be inhibited in part by alerting glutamate release or biosynthesis presynaptically.

Pathogenic mechanisms in familial amyotrophic lateral sclerosis due to mutation of Cu, Zn superoxide dismutase

Oxidative mechanisms of damage have been implicated indirectly in the damage to brain tissue caused acutely by ischemia or chronically by neurodegenerative diseases. A direct link between pathogenesis and antioxidant enzyme systems has come from studies of a genetic form of amyotrophic lateral sclerosis (ALS). ALS causes the degeneration of motor neurons in cortex, brainstem and spinal cord with consequent progressive paralysis and death. The disease occurs in both sporadic and familial forms. Some 20% of kindreds in which ALS is inherited in an autosomal dominant fashion have mutations in the gene (SOD1) encoding Cu, Zn superoxide dismutase (SOD). Several SOD1 mutations have been shown by ourselves and others to cause motor neuron disease when expressed at high levels in transgenic mice, whereas transgenic mice expressing comparable amounts of wild-type human SOD do not show clinical disease. Thus, we have argued that motor neuron disease is caused by gain-of-function mutations in the human SOD1 gene. Our current experiments investigate the link between mutation of SOD1 and oxidative pathways of damage.

Age-dependent penetrance of disease in a transgenic mouse model of familial amyotrophic lateral sclerosis

The mutation gly93-->ala of Cu,Zn superoxide dismutase (SOD) is found in patients with familial amyotrophic lateral sclerosis and causes motor neuron disease when expressed in transgenic mice. The progression of clinical and pathological disease was studied in a line of mice designated G1H. Clinical disease started at 91 +/- 14 days of age with fine shaking of the limbs, followed by paralysis and death by 136 +/- 7 days of age. Pathological changes begin by 37 days of age with vacuoles derived from swollen mitochondria accumulating in motor neurons. At the onset of clinical disease (90 days), significant death of somatic motor neurons innervating limb muscles has occurred; mice at end-stage disease (136 days) show up to 50% loss of cervical and lumbar motor neurons. However, neither thoracic nor cranial motor neurons show appreciable loss despite vacuolar changes. Autonomic motor neurons also are not affected. Mice that express wild-type human Cu,Zn SOD remain free of disease, indicating that mutations cause neuron loss by a gain-of-function. Thus, the age-dependent penetrance of motor neuron disease in this transgenic model is due to the gradual accumulation of pathological damage in select populations of cholinergic neurons.