Signatures of miR-181a on the Renal Transcriptome and Blood Pressure

MicroRNA-181a binds to the 3′ untranslated region of messenger RNA (mRNA) for renin, a rate-limiting enzyme of the renin-angiotensin system. Our objective was to determine whether this molecular interaction translates into a clinically meaningful effect on blood pressure and whether circulating miR-181a is a measurable proxy of blood pressure. In 200 human kidneys from the TRANScriptome of renaL humAn TissuE (TRANSLATE) study, renal miR-181a was the sole negative predictor of renin mRNA and a strong correlate of circulating miR-181a. Elevated miR-181a levels correlated positively with systolic and diastolic blood pressure in TRANSLATE, and this association was independent of circulating renin. The association between serum miR-181a and systolic blood pressure was replicated in 199 subjects from the Genetic Regulation of Arterial Pressure of Humans In the Community (GRAPHIC) study. Renal immunohistochemistry and in situ hybridization showed that colocalization of miR-181a and renin was most prominent in collecting ducts where renin is not released into the systemic circulation. Analysis of 69 human kidneys characterized by RNA sequencing revealed that miR-181a was associated with downregulation of four mitochondrial pathways and upregulation of 41 signaling cascades of adaptive immunity and inflammation. We conclude that renal miR-181a has pleiotropic effects on pathways relevant to blood pressure regulation and that circulating levels of miR-181a are both a measurable proxy of renal miR-181a expression and a novel biochemical correlate of blood pressure.     

Studies in vitro on the effects of 1H,2H,4H(5H)-octafluorocyclohexane and 1H,4H(2H)-nonafluorocyclohexane on enzymes and organelles

A comparison has been made of the effect of 1H,2H,4H(5H)-octafluorocyclohexane, which is highly toxic (LD(50) 17mg./kg. in rats), and of 1H,4H(2H)-nonafluorocyclohexane, which is relatively non-toxic (LD(50)>440mg./kg. in rats), on the respiration of rat liver homogenates and mitochondria in vitro. 1H,2H,4H(5H)-Octafluorocyclohexane strongly inhibited the respiration of both homogenates and mitochondria, but neither compound had any significant effect on glycolysis or on glutamate dehydrogenase or NADH-cytochrome c reductase activity. 1H,2H,4H(5H)-Octafluorocyclohexane, however, caused a very marked inhibition of cytochrome oxidase activity, causing an almost complete lesion in this region of the respiratory chain. 1H,4H(2H)-Nonafluorocyclohexane was without effect in this respect. A marked decrease in turbidity of mitochondrial suspensions at 520nm. was caused by addition of both compounds, the effect being greater with 1H,2H,4H(5H)-octafluorocyclohexane. ATP, Mg(2+) and bovine serum albumin did not reverse these changes. Mitochondrial adenosine triphosphatase activity was increased twofold by the toxic compound, but only slightly by the non-toxic compound. Electron-microscopic examination of mitochondria treated with 1H,2H,4H(5H)-octafluorocyclohexane revealed gross morphological damage, whereas the effect of 1H,4H(2H)-nonafluorocyclohexane appeared to be merely to cause swelling. The results obtained account, to some extent at any rate, for the toxic effects of 1H,2H,4H(5H)-octafluorocyclohexane.     

禽流感H5N1病毒感染BALB/c小鼠后多器官病变初探

为了研究禽流感H5N1病毒在各个器官的增殖和病理变化,在生物安全实验室,我们将禽流感H5N1病毒通过尾静脉接种BALB/C小鼠。结果小鼠在不经过适应的情况下,直接感染发病,甚至死亡。在观察的7天内,感染小鼠临床症状主要表现呼吸急促,体温、体重下降。尸检表现肺出血,心外膜坏死以及肝脏的坏死。组织病理检查表现心、肝、肺等多器官的病变。肺的病变伴有纤维化的弥漫性肺泡损伤;心肌外膜大量淋巴细胞浸润、坏死;肝细胞大量坏死,淋巴细胞浸润。心、肝的坏死病变在H5N1禽流感病毒相关的研究中未见报道。经过对各个组织器官的病毒载量的检测,未发现病毒在各个病变组织中的复制。免疫组化的检测,各个组织中也未检出阳性的细胞反应。因此,我们认为H5N1禽流感病毒感染小鼠引起多个器官组织的损伤,甚至死亡,不是病毒在器官的复制,而可能是病毒感染小鼠,产生炎症细胞因子的高度表达,损伤多个器官组织所致。     

Does small-sided-games’ court area influence metabolic,perceptual, and physical performance parameters of young elite basketball players?

The purpose of this study was to investigate the effect of court size on physiological responses and physical performance of young elite basketball players. Twelve male basketball players (18.6 ± 0.5 years; 88.8 ± 14.5 kg; 192.6 ± 6.5 cm) from an under-19 team performed two small-sided games (matches) with different court areas (28x15 m and 28x9 m; 28x15 and 28x9 protocols). The number of players (3x3) was kept the same in each protocol. The players performed a repeated-sprint ability (RSA) test before and after each match. Blood lactate concentration was collected before (pre) and after (post) the matches, and the session rating of perceived exertion (session-RPE) was determined 30 minutes after the match. Best and mean time in the RSA test were not different between the 28x15 and the 28x9 match protocols (p > 0.05). A significant difference was observed for lactate concentration from pre- to post-match (p < 0.05) in both protocols (28x15 and 28x9); however, there was no significant interaction between protocols. A similar session-RPE mean score (28x15: 7.2 ± 1.4 and 28x9: 6.6 ± 1.4) was detected for both protocols (p > 0.05, ES=0.41). In summary, the results of the current study suggest that the different court areas induced similar responses. Although there was no significant difference in effort perception, players tended to perceive a greater effort in the larger court size.     

Downregulation of glutaredoxin but not glutathione loss leads to mitochondrial dysfunction in female mice CNS: implications in excitotoxicity

Oxidative stress, excitotoxicity and mitochondrial dysfunction play synergistic roles in neurodegeneration. Maintenance of thiol homeostasis is important for normal mitochondrial function and dysregulation of protein thiol homeostasis by oxidative stress leads to mitochondrial dysfunction and neurodegeneration. We examined the critical roles played by the antioxidant, non-protein thiol, glutathione and related enzyme, glutaredoxin in maintaining mitochondrial function during excitotoxicity caused by beta-N-oxalyl amino-L-alanine (L-BOAA), the causative factor of neurolathyrism, a motor neuron disease involving the pyramidal system. L-BOAA causes loss of GSH and inhibition of mitochondrial complex I in lumbosacral cord of male mice through oxidation of thiol groups, while female mice are resistant. Reducing GSH levels in female mice CNS by pretreatment with diethyl maleate or L-propargyl glycine did not result in inhibition of complex I activity, unlike male mice. Further, treatment of female mice depleted of GSH with L-BOAA did not induce inhibition of complex I indicating that GSH levels were not critical for maintaining complex I activity in female mice unlike their male counterpart. Glutaredoxin, a thiol disulfide oxidoreductase helps maintain redox status of proteins and downregulation of glutaredoxin results in loss of mitochondrial complex I activity. Female mice express higher levels of glutaredoxin in certain CNS regions and downregulation of glutaredoxin using antisense oligonucleotides sensitizes them to L-BOAA toxicity seen as mitochondrial complex I loss. Ovariectomy downregulates glutaredoxin and renders female mice vulnerable to L-BOAA toxicity as evidenced by activation of AP1, loss of GSH and complex I activity indicating the important role of glutaredoxin in neuroprotection. Estrogen protects against mitochondrial dysfunction caused by excitotoxicity by maintaining cellular redox status through higher constitutive expression of glutaredoxin in the CNS. Therapeutic interventions designed to upregulate glutaredoxin may offer neuroprotection against excitotoxicity in motor neurons.     

Antibodies targeting the PfRH1 binding domain inhibit invasion of Plasmodium falciparum merozoites

Invasion by the malaria merozoite depends on recognition of specific erythrocyte surface receptors by parasite ligands. Plasmodium falciparum uses multiple ligands, including at least two gene families, reticulocyte binding protein homologues (RBLs) and erythrocyte binding proteins/ligands (EBLs). The combination of different RBLs and EBLs expressed in a merozoite defines the invasion pathway utilized and could also play a role in parasite virulence. The binding regions of EBLs lie in a conserved cysteine-rich domain while the binding domain of RBL is still not well characterized. Here, we identify the erythrocyte binding region of the P. falciparum reticulocyte binding protein homologue 1 (PfRH1) and show that antibodies raised against the functional binding region efficiently inhibit invasion. In addition, we directly demonstrate that changes in the expression of RBLs can constitute an immune evasion mechanism of the malaria merozoite.     

Immunohistochemical localization of leukemia inhibitory factor, interleukins 1 and 6 at the primary implantation site in the rhesus monkey

Blastocyst implantation and placentation involve localized inflammatory type of responses at and around the site of nidation. In the present study, the likely involvement of inflammatory cytokines, namely, leukemia inhibitory factor (LIF), interleukins 1 alpha and 1 beta (IL-1alpha and IL-1beta) and IL-6 at the primary implantation site of the rhesus monkey was examined immunocytochemically during lacunar (n=6) and villous (n=8) stages of gestation. Trophoblast cells and extraembryonic mesenchymal cells were immunopositive for LIF and IL-1alpha. The distribution of IL-1beta and IL-6 in trophoblast cells was low in lacunar stage samples, however, a higher degree of immunopositivity for IL-6 was observed in villous stage samples. Decidual cells were immunopositive for all the cytokines studied. In lacunar stage samples, plaque cells adjacent to implanted nidus were immunopositive for all the cytokines examined, and the degree of their immunoprecipitation increased, except that of IL-1beta, during the villous stage. Luminal and glandular epithelial cells were immunopositive for LIF, IL-1alpha, IL-1beta and IL-6 in lacunar and in villous stage samples. LIF immunopositivity was detected in endothelial cells of blood vessels within and below chorionic plate and cytotrophoblast shell, while vascular smooth muscle cells were positive for all the cytokines studied. The temporo-spatial characteristics of LIF, IL-1alpha, IL-1beta and IL-6 protein expressions in primary implantation sites of the rhesus monkey suggest that these pro-inflammatory cytokines play specific roles in regulating trophoblast cell proliferation, differentiation, invasion and associated maternal tissue remodelling during early gestation.     

Zinc protoporphyrin IX binds heme crystals to inhibit the process of crystallization in Plasmodium falciparum

The intraerythrocytic Plasmodium falciparum parasite converts most of host hemoglobin heme into a nontoxic heme crystal. Erythrocyte zinc protoporphyrin IX, normally present at 0.5 microM, which is a ratio of 1:40,000 hemes, can elevate 10-fold in some of the anemias associated with malaria disease protection. This work examines a binding mechanism for zinc protoporphyrin IX inhibition of heme crystallization similar to the antimalarial quinolines. Zinc protoporphyrin IX neither forms crystals alone nor extends on preformed heme crystals. Inhibition of both seed heme crystal formation and crystal extension occurs with an inhibitory concentration (IC)50 of 5 microM. Field emission in-lens scanning electron microscopy depicts the transition and inhibition of heme monomer aggregates to heme crystals with and without seeding of preformed hemozoin templates. In vitro zinc protoporphyrin IX, like the quinolines, binds to heme crystals in a saturable, specific, pH, and time-dependent manner. The ratio at saturation is approximately 1 zinc protoporphyrin IX per 250 hemes of the crystal. Unlike the quinolines, zinc protoporphyrin IX binds measurably in the absence of heme. Isolated ring and trophozoite stage parasites have an elevated zinc protoporphyrin IX to heme ratio 6 to 10 times that in the erythrocyte cytosol, which also corresponds to elevated ratios found in heme crystals purified from Plasmodium parasites. This work implicates protection from malaria by a mechanism where elevated zinc protoporphyrin IX in anemic erythrocytes binds to heme crystals to inhibit further crystallization. In endemic malaria areas, severe iron deficiency anemia should be treated with antimalarials along with iron replenishment.     

Plant responses to elevated CO<Subscript>2</Subscript> concentration at different scales: leaf,whole plant,canopy, and population

Elevated CO₂ enhances photosynthesis and growth of plants, but the enhancement is strongly influenced by the availability of nitrogen. In this article, we summarise our studies on plant responses to elevated CO₂. The photosynthetic capacity of leaves depends not only on leaf nitrogen content but also on nitrogen partitioning within a leaf. In Polygonum cuspidatum, nitrogen partitioning among the photosynthetic components was not influenced by elevated CO₂ but changed between seasons. Since the alteration in nitrogen partitioning resulted in different CO₂-dependence of photosynthetic rates, enhancement of photosynthesis by elevated CO₂ was greater in autumn than in summer. Leaf mass per unit area (LMA) increases in plants grown at elevated CO₂. This increase was considered to have resulted from the accumulation of carbohydrates not used for plant growth. With a sensitive analysis of a growth model, however, we suggested that the increase in LMA is advantageous for growth at elevated CO₂ by compensating for the reduction in leaf nitrogen concentration per unit mass. Enhancement of reproductive yield by elevated CO₂ is often smaller than that expected from vegetative growth. In Xanthium canadense, elevated CO₂ did not increase seed production, though the vegetative growth increased by 53%. As nitrogen concentration of seeds remained constant at different CO₂ levels, we suggest that the availability of nitrogen limited seed production at elevated CO₂ levels. We found that leaf area development of plant canopy was strongly constrained by the availability of nitrogen rather than by CO₂. In a rice field cultivated at free-air CO₂ enrichment, the leaf area index (LAI) increased with an increase in nitrogen availability but did not change with CO₂ elevation. We determined optimal LAI to maximise canopy photosynthesis and demonstrated that enhancement of canopy photosynthesis by elevated CO₂ was larger at high than at low nitrogen availability. We also studied competitive asymmetry among individuals in an even-aged, monospecific stand at elevated CO₂. Light acquisition (acquired light per unit aboveground mass) and utilisation (photosynthesis per unit acquired light) were calculated for each individual in the stand. Elevated CO₂ enhanced photosynthesis and growth of tall dominants, which reduced the light availability for shorter subordinates and consequently increased size inequality in the stand.