Vitamin K2 protects mice against non-alcoholic fatty liver disease induced by high-fat diet

Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide and there is a huge unmet need to find safer and more effective drugs. Vitamin K has been found to regulate lipid metabolism in the liver. However, the effects of vitamin K2 on NAFLD is unclear. This study aims to evaluate the preventive and therapeutic effects of vitamin K2 in the process of fatty liver formation and to explore molecular mechanisms the associated with lipid metabolism. A non-alcoholic fatty liver model was established by high-fat diet administration for three months. Vitamin K2 significantly reduced the body weight, abdominal circumference and body fat percentage of NAFLD mice. Vitamin K2 also showed histological benefits in reducing hepatic steatosis. NAFLD mice induced by high-fat diet showed increased HMGR while vitamin K2 intervention could reverse the pathological lterations. Adiponectin (APN) is an endogenous bioactive polypeptide or protein secreted by adipocytes. We detected APN, SOD, AlaDH and other indicators that may affect the state of high-fat diet mice, but the experimental results showed that the above indicators did not change significantly. It is worth noting that the effect of vitamin K2 supplementation on the lipid-lowering effect of uc OC in vivo needs to be further explored. This study first reported the protective effect of vitamin K2 on high-fat diet-induced NAFLD in mice. The protective effect of vitamin K2 may be related to the improvement of lipid metabolism disorder in NAFLD.

A Human Brain Model Mimicking Umbilical Cord Mesenchymal Stem Cells for the Treatment of Hypoxic-Ischemic Brain Injury

We used an in vitro model of the human brain immune microenvironment to simulate hypoxic-ischemic brain injury (HIBI) and treatment with human umbilical cord mesenchymal stem cells (hUMSCs) to address the transformation barriers of gene differences between animals and humans in preclinical research. A co-culture system, termed hNAME, consisted of human hippocampal neurons (N), astrocytes (A), microglia (M), and brain microvascular endothelial cells (E). Flow cytometry measured the apoptosis rates of neurons and endothelial cells. hNAME-neurons and endothelial cells experienced more severe damage than monolayer cells, particularly after 48 h and 24 h of reoxygenation (OGD48/R24). Western blotting identified neuroinflammatory response markers, including HIF-1α, C1q, C3, TNF-α, and iNOS. Inflammatory factors originated from the glial chamber rather than the neurons and vascular endothelial chambers. A gradual increase in the release of inflammatory factors was observed as the OGD and reoxygenation times increased, peaking at OGD48/R24. The hNAME value was confirmed in human umbilical cord mesenchymal stem cells (hUMSCs). Treatment with hUMSCs resulted in a notable decrease in the severity of neuronal and endothelial cell damage in hNAME. The hNAME is an ideal in vitro model for simulating the immune microenvironment of the human brain because of the interactions between neurons, vessels, astrocytes, and microglia.

Effects of Non-directional Mechanical Trauma on Gastrointestinal Tract Injury in Rats

Mechanical trauma can (MT) cause secondary injury, such as cardiomyocyte apoptosis and cardiac dysfunction has been reported. However, the effects of mechanical trauma on gastrointestinal tract is unclear. This study aims to observe the main location and time of gastrointestinal tract injury caused by non-directional trauma and explain the reason of the increase of LPS in blood caused by mechanical injury. Morphological changes in the stomach, ileum and cecum at different time points after MT were observed in this experiment. The results reveal that the injury to the cecal mucosa in the rats was more obvious than that in the ileum and the stomach. The cecal epithelial cell junction was significantly widened at 20 min after MT, and the plasma LPS and D-lactic acid concentrations increased significantly at the same time point. In addition, some bacterial structures in the widened intercellular space and near the capillary wall of the cecal mucosa were detected at 12 h after MT. This finding suggests that the main reason for the increase in LPS in plasma after MT is cecal mucosal injury. This study is important for the early intervention of the gastrointestinal tract to prevent secondary injury after MT.

Short-Term Efficacy and Safety of Switching from a Latanoprost/Timolol Fixed Combination to a Latanoprost/Carteolol Fixed Combination

Purpose

To investigate the short-term intraocular pressure-lowering efficacy and safety of switching from a fixed combination of latanoprost/timolol to a fixed combination of latanoprost/carteolol.

Patients and Methods

The subjects were 30 eyes of 30 adult patients with primary open-angle glaucoma, normal-tension glaucoma, or ocular hypertension who were using a latanoprost-/timolol-fixed combination with insufficient intraocular pressure-lowering efficacy or adverse reactions. The subjects were switched from once-daily latanoprost/timolol to once-daily latanoprost/carteolol with no washout interval. Intraocular pressure, tear film break-up time, corneal epithelial defects, conjunctival hyperemia, blood pressure, and pulse rate were measured and compared before and 1 and 3 months after switching. Patients were monitored for adverse reactions at each visit, and dropouts were recorded.

Results

The mean intraocular pressure at 1 month (15.9±3.1 mmHg) and 3 months (16.3±3.8 mmHg) was not significantly different from that at baseline (16.1±3.1 mmHg). The tear film break-up time and corneal epithelial defects were significantly improved after switching (p<0.01 and p<0.0001, respectively). There was a significant decrease in systolic blood pressure after 1 month and diastolic pressure after 3 months (p<0.05). There was no significant change in pulse rate during the study. Adverse reactions (blurred vision, blepharitis, and conjunctival hyperemia) occurred in 3 patients (10.0%). Four patients (13.3%) discontinued treatment during the 3-month study period.

Conclusion

A switch from a fixed combination of latanoprost/timolol to that of latanoprost/carteolol can maintain intraocular pressure and adherence with once-daily administration while improving tear film break-up time and corneal epithelial defects.

Potential role of tracing stem cell transplantation and effects on the immune cell function of ferumoxytol combining with heparin and protamine in vivo/in vitro

Cell labeling and tracing have played an increasingly important role in the field of stem cell transplantation. Nanocomplexes combining three Food and Drug Administration (FDA)-approved drugs: heparin (H), protamine (P), and ferumoxytol (F) (HPF nanocomplexes) display high labeling efficiency in human adipose tissue-derived stem cells (hADSCs), but their biological safety has not been determined. In this study, we tested the labeling efficiency of HPF in hADSCs through in vitro cytotoxicity studies and in vivo murine preclinical studies using HPF-labeled hADSCs. The labeling process did not cause cell apoptosis and had little effect on cell proliferation. In vivo magnetic resonance imaging (MRI) showed that the HPF-labeled cells produced a hypointense signal that did not affect liver and kidney functions. However, after injection of HPF-labeled cells into mice, lymphocyte transformation testing showed that T and B lymphocyte proliferation was significantly increased. These findings suggest that extensive safety testing of HPF nanocomplexes is necessary; the process to evaluate HPF as an investigative new drug application could therefore be postponed.

2,5-Hexanedione induces autophagic death of VSC4.1 cells via a PI3K/Akt/mTOR pathway

2,5-Hexanedione (HD) is an important bioactive metabolite ofn-hexane, which mediates the neurotoxicity of the parent compound.

TRIP12 as a mediator of human papillomavirus/p16-related radiation enhancement effects

Patients with human papillomavirus (HPV)-positive head and neck squamous cell carcinoma (HNSCC) have better responses to radiotherapy and higher overall survival rates than do patients with HPV-negative HNSCC, but the mechanisms underlying this phenomenon are unknown. p16 is used as a surrogate marker for HPV infection. Our goal was to examine the role of p16 in HPV-related favorable treatment outcomes and to investigate the mechanisms by which p16 may regulate radiosensitivity. HNSCC cells and xenografts (HPV/p16-positive and -negative) were used. p16-overexpressing and small hairpin RNA-knockdown cells were generated, and the effect of p16 on radiosensitivity was determined by clonogenic cell survival and tumor growth delay assays. DNA double-strand breaks (DSBs) were assessed by immunofluorescence analysis of 53BP1 foci; DSB levels were determined by neutral comet assay; western blotting was used to evaluate protein changes; changes in protein half-life were tested with a cycloheximide assay; gene expression was examined by real-time polymerase chain reaction; and data from The Cancer Genome Atlas HNSCC project were analyzed. p16 overexpression led to downregulation of TRIP12, which in turn led to increased RNF168 levels, repressed DNA damage repair (DDR), increased 53BP1 foci and enhanced radioresponsiveness. Inhibition of TRIP12 expression further led to radiosensitization, and overexpression of TRIP12 was associated with poor survival in patients with HPV-positive HNSCC. These findings reveal that p16 participates in radiosensitization through influencing DDR and support the rationale of blocking TRIP12 to improve radiotherapy outcomes.

Human adipose-derived mesenchymal stem cells: a better cell source for nervous system regeneration

BACKGROUND

In order to suggest an ideal source of adult stem cells for the treatment of nervous system diseases, MSCs from human adipose tissue and bone marrow were isolated and studied to explore the differences with regard to cell morphology, surface markers, neuronal differentiation capacity, especially the synapse structure formation and the secretion of neurotrophic factors.

METHODS

The neuronal differentiation capacity of human mesenchymal stem cells from adipose tissue (hADSCs) and bone marrow (hBMSCs) was determined based on nissl body and synapse structure formation, and neural factor secretion function. hADSCs and hBMSCs were isolated and differentiated into neuron-like cells with rat brain-conditioned medium, a potentially rich source of neuronal differentiation promoting signals. Specific neuronal proteins and neural factors were detected by immunohistochemistry and enzyme-linked immunosorbent assay analysis, respectively.

RESULTS

Flow cytometric analysis showed that both cell types had similar phenotypes. Cell growth curves showed that hADSCs proliferated more quickly than hBMSCs. Both kinds of cells were capable of osteogenic and adipogenic differentiation. The morphology of hADSCs and hBMSCs changed during neuronal differentiation and displayed neuron-like cell appearance after 14 days' differentiation. Both hADSCs and hBMSCs were able to differentiate into neuron-like cells based on their production of neuron specific proteins including β-tubulin-III, neuron-specific enolase (NSE), nissl bodies, and their ability to secrete brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF). Assessment of synaptop hysin and growth-associated protein-43 (GAP-43) suggested synapse structure formation in differentiated hADSCs and hBMSCs.

CONCLUSIONS

Our results demonstrate that hADSCs have neuronal differentiation potential similar to hBMSC, but with a higher proliferation capacity than hBMSC. Adipose tissue is abundant, easily available and would be a potential ideal source of adult stem cells for neural-related clinical research and application.

Conditioned medium of human adipose-derived mesenchymal stem cells mediates protection in neurons following glutamate excitotoxicity by regulating energy metabolism and GAP-43 expression

Glutamate excitotoxicity has been implicated as one of the pathological mechanisms contributing to neuronal cell death and is involved in many neurological disorders. Stem cell transplantation is a promising approach for the treatment of nervous system damage or diseases. Previous studies have shown that mesenchymal stem cells (MSCs) have important therapeutic effects in experimental animal and preclinical disease model of central nervous system pathology. However, it is not well understood whether neurogenesis of MSCs or MSC conditioned-medium (CM) containing microparticles mediates therapeutic effects. Here, we investigated the neuroprotective effects of human adipose-derived MSCs (AMSCs) on cortical neurons using models of glutamate excitotoxicity. Following exposure to glutamate (100 μM, 15 min), cortical neurons were co-cultured with either AMSCs separated by a semiporous membrane (prohibiting direct cell-cell contact) or with AMSC-CM for 18 h. Compared to untreated control groups, AMSCs and AMSC-CM partially and similarly reduced neuronal cell damages, as indicated by reduced LDH release, a decreased number of trypan-positive cells and a decline in the number of apoptotic nuclei. Protection by CM was associated with increased GAP-43 expression and an elevated number of GAP-43-positive neurites. Furthermore, CM increased levels of ATP, NAD(+) and NADH and the ratio of NAD(+)/NADH, while preventing a glutamate-induced decline in mitochondrial membrane potential. These results demonstrate that AMSC-CM mediates direct neuroprotection by inhibiting neuronal cell damage/apoptosis, promoting nerve regeneration and repair, and restoring bioenergy following energy depletion caused by glutamate excitotoxicity.

Rapid and transient upregulation of CCL11 (eotaxin-1) in mouse ovary during terminal stages of follicular development

PROBLEM

This study aimed to investigate the regulation of expression, localization and physiological role of the CCL11/CCR3 axis in mouse ovary during the periovulatory period.

METHOD OF STUDY

CCL11/CCR3 expression in the mouse ovary after treatment with pregnant mare serum gonadotropin (PMSG) followed by human chorionic gonadotropin (hCG) 48 hr later was assessed in vivo and in 3-dimensional cultures in vitro.

RESULTS

Real-time RT-PCR analyses revealed transient CCL11 mRNA upregulation 6 hr after hCG treatment. Immunohistochemical staining of serial ovarian sections demonstrated overlapping expression of CCL11, CCR3 and CD31 endothelial cell marker in the theca-interstitial layer at 10 hr after hCG treatment. In vitro 3-dimensional cultures of periovulatory ovarian tissues demonstrated that treatment with anti-CCL11 neutralizing antibody significantly decreased CD31 transcript.

CONCLUSIONS

Gonadotropin surge leads to transient CCL11/CCR3 axis upregulation in the ovarian theca-interstitial layer, suggesting that it is involved in periovulatory physiological processes by affecting follicular vessels.

Campylobacter jejuni DNA-binding protein from starved cells in Guillain-Barré syndrome patients

Campylobacter jejuni enteritis is frequently associated with an axonal form of Guillain-Barré syndrome (GBS) and C. jejuni DNA-binding protein from starved cells (C-Dps) induces paranodal myelin detachment and axonal degeneration through binding with sulfatide in vivo. Here we investigated the invasion of C-Dps into hosts with C. jejuni-related GBS. Our analyses of patient sera found that both C-Dps and anti-C-Dps antibodies were most commonly detected in sera from C. jejuni-related GBS patients (5/27, 14.8% and 15/24, 62.5%; respectively). These findings suggest that C-Dps invades the host and may potentially contribute to the peripheral nerve damage in C. jejuni-related GBS.

Simvastatin attenuates hypomyelination induced by hypoxia-ischemia in neonatal rats

OBJECTIVES

Simvastatin, the most widely used cholesterol-lowering drug, has been reported to protect the adult brain from ischemia. Nevertheless, little is known about its action on developing brain after stroke. Although a few reports have found recently that simvastatin displays anti-inflammation and anti-apoptosis properties and improves the cognitive and morphological consequences in the neonatal rats after hypoxia-ischemia (HI) damage, to our best knowledge, there has been no study of the effect of it on myelin formation after neonatal brain damage. Therefore, we investigated whether simvastatin could promote the myelination of oligodendrocytes in the neonatal rats after HI and explored the possible role of microglial responses in this process.

METHODS

Postnatal day 7 Sprague-Dawley rats were subjected to HI. White matter integrity and myelination were evaluated by the densitometry of myelin basic protein (MBP) immunostaining. OX-42 immunoreactivity and nissl staining were used for identifying microglial responses and the structure changes of white matter and adjacent gray matter after HI. Simvastatin was administrated prophylactically to rats.

RESULTS

HI induced serious hypomyelination especially in external and internal capsules 3 and 7 days after HI, accompanying with microglial activation remarkably. Simvastatin treatment greatly increased the densities of MBP immunostaining, inhibited microglial activation and reduced the numbers of pyknotic cells and neuronal loss.

DISCUSSION

The present study shows that simvastatin treatment in neonatal rats attenuates HI-induced developing oligodendrocytes injury and hypomyelination. Its anti-inflammatory properties via suppression of microglial activation are likely to contribute to this action. It provides experimental evidence to support the neuroprotective effects of statins in neonatal ischemic stroke.

Association of anti-Helicobacter pylori neutrophil-activating protein antibody response with anti-aquaporin-4 autoimmunity in Japanese patients with multiple sclerosis and neuromyelitis optica

There are two distinct subtypes of multiple sclerosis (MS) in Asians: opticospinal (OSMS) and conventional (CMS). OSMS has similar features to neuromyelitis optica (NMO) and half of OSMS patients have the NMO-Immunoglobulin G (IgG)/ anti-aquaporin-4 (AQP4) antibody. We reported that Helicobacter pylori (H. pylori) infection was significantly less common in CMS patients than controls. To reveal the immune responses to the H. pylori neutrophil-activating protein (HP-NAP) in Japanese MS patients, according to anti-AQP4 antibody status, sera from 162 MS patients, 37 patients with other inflammatory neurological diseases (OIND), and 85 healthy subjects were assayed for anti-H. pylori antibodies, anti-HP-NAP antibodies, and myeloperoxidase (MPO) by enzyme immunoassays. H. pylori seropositivity rates were significantly higher in anti-AQP4 antibody-positive MS/NMO (AQP4 + /MS) patients (19/27, 70.4%) than anti-AQP4 antibody-negative CMS (AQP4 - /CMS) patients (22/83, 26.5%). Among H. pylori-infected individuals, the anti-HP-NAP antibody was significantly more common in AQP4 + /MS and AQP4 - /OSMS patients than healthy subjects (36.8%, 34.6% versus 2.8%). Among the AQP4 + /MS patients, a significant positive correlation between anti-HP-NAP antibody levels and the final Kurtzke's Expanded Disability Status Scale scores was found, and MPO levels were higher in anti-HP-NAP antibody-positive patients than anti-HP-NAP antibody-negative ones. Therefore, HP-NAP may be associated with the pathology of anti-AQP4 antibody-related neural damage in MS/NMO patients.

Hypoxia-ischemia brain damage disrupts brain cholesterol homeostasis in neonatal rats

PURPOSE

The first 3 weeks of life is the peak time of oligodendrocytes development and also the critical period of cholesterol increasing dramatically in central nervous system in rats. Neonatal hypoxia-ischemia (HI) brain damage happening in this period may disturb the brain cholesterol balance as well as white matter development.

MATERIALS AND METHODS

To test this hypothesis, postnatal day 7 (P7) Sprague-Dawley rats were subjected to HI insult. Cholesterol concentrations from brain and plasma were measured. White matter integrity was evaluated by densitometric analysis of myelin basic protein (MBP) immunostaining and electron microscopy. Brain TNF-alpha and IL-6 levels were also measured.

RESULTS

HI-induced brain cholesterol, but not the plasma cholesterol, levels decreased significantly during the first three days after HI compared with naïve and sham operated rats (p<0.05). Obvious hypomyelination was indicated by marked reductions in MBP immunostaining on both P10 and P14 (p<0.01) and less and thinner myelinated axons were detected on P21 by electron microscopy observation. High expressions of brain TNF-alpha and IL-6 12 h after HI (p<0.05) were also observed.

DISCUSSION

The present work provides evidence that HI insult destroyed brain cholesterol homeostasis, which might be important in the molecular pathology of hypoxic-ischemic white matter injury. Proinflammatory cytokines insulting oligodendrocytes, may cause cholesterol unbalance. Furthermore, specific therapeutic interventions to maintain brain cholesterol balance may be effective for the recovery of white matter function.

Ghrelin stimulates milk intake by affecting adult type feeding behaviour in postnatal rats

The influence of ghrelin on feeding behaviour during infancy is unknown. To determine whether ghrelin influences milk intake in rat pups, newborn rats received a single i.p. injection of either rat ghrelin (100 microg/kg) or rabbit anti-ghrelin immunoglobulin G (100 microg/kg) every 5 days from postpartum day 5 to day 30 (P5-P30). Milk intake was then assessed by body weight gain following a 2-h suckling period. Ghrelin significantly increased weight gain relative to vehicle-injected controls in P20, P25 and P30 pups, but not in younger animals. Similarly, after 8 h of milk restriction, anti-ghrelin injections significantly decreased weight gain in P25 and P30, but not in younger pups. Interestingly, however, ghrelin did increase independent feeding in P10 and P15 pups using a paradigm in which pups consumed milk from a milk-soaked paper towel. We therefore conclude that ghrelin stimulates milk intake at an early postnatal stage, primarily by affecting adult-type feeding behaviour.

[Evidence for a major role of Mg2+ in VEGF165-mediated angiogenesis]

OBJECTIVE

The effect of vascular endothelial growth factor(165) (VEGF(165)) on intracellular free magnesium ([Mg(2+)](i)) and the relationship between Mg(2+) and angiogenesis in human umbilical vein endothelial cells (HUVECs) were investigated in this study.

METHODS

[Mg(2+)](i) in HUVECs loaded with fluorescent magnesium indicator mag-fura-2 were quantitatively detected with the use of intracellular cation measurement system. HUVECs were obtained from normal fetus and cultured in M199 with 0.2 fetal bovine serum. The angiogenesis effects of VEGF(165) were observed in presence of 0 mmol/L, 1 mmol/L or 2 mmol/L of extracellular Mg(2+).

RESULTS

VEGF(165) significantly increased [Mg(2+)](i) in a dose-dependent manner independent of extracellular Mg(2+), Na(+) and Ca(2+) and this effect could be blocked by pretreatment with VEGF(165) receptor-2 (KDR) inhibitor (SU1498). The angiogenesis induced by VEGF(165) was significantly inhibited cells with 0 mmol/L extracellular Mg(2+), the angiogenesis effects of VEGF(165) were similar in cells with 1 mmol/L and 2 mmol/L extracellular Mg(2+) and these effects could be blocked by SU1498.

CONCLUSIONS

These results suggest that the [Mg(2+)](i) increase induced by VEGF(165) originates from intracellular Mg(2+) pools and promotes angiogenesis via KDR-dependent signaling pathways.

The selective Rho-kinase inhibitor Fasudil is protective and therapeutic in experimental autoimmune encephalomyelitis

We studied the role of fasudil, a selective Rho-kinase inhibitor, in experimental autoimmune encephalomyelitis (EAE). Both parenteral and oral administration of fasudil prevented the development of EAE induced by proteolipid protein (PLP) p139-151 in SJL/J mice. Specific proliferation of lymphocytes to PLP was significantly reduced, together with a downregulation of interleukin (IL)-17 and a marked decrease of the IFN-gamma/IL-4 ratio. Immunohistochemical examination also disclosed a marked decrease of inflammatory cell infiltration, and attenuated demyelination and acute axonal transaction. These results may provide a rationale of selective blockade of Rho-kinase by oral use of fasudil as a new therapy for multiple sclerosis.

Biotransformation of letrozole in rat liver microsomes: effects of gender and tamoxifen

The in vitro metabolic kinetics of letrozole were investigated by incubating letrozole (10-500 microM) in female or male rat liver microsomes to assess the effect of gender and to predict the in vivo biotransformation characteristics of letrozole in rats. The effects of tamoxifen (TAM) on the metabolic kinetics of letrozole were also examined by incubating letrozole in female rat liver microsomes in the presence or absence of TAM. The effects of chronic pretreatment of female rats with TAM (0.5, 1.0, 5.0 mg/kg/day, i.p. for 7 consecutive days) on liver microsomal protein content and metabolic activity were also examined. The formation rate of the carbinol metabolite of letrozole, CGP44 645, was significantly higher (p<0.05) in male rat liver microsomes in comparison to female. The V(max)/K(m) ratio for letrozole metabolism in female rat liver microsomes did not change significantly (p>0.05) in the presence of TAM. After chronic pretreatment of female rats with TAM (up to a dose of 1.0mg/kg/day), the hepatic microsomal protein content was significantly increased but the formation rate of CGP44 645, when normalized for protein content, did not change significantly. These results suggest that there is a marked gender difference in letrozole metabolism in rats. It also appears that acute treatment of female rat liver microsomes with TAM produces negligible inhibitory effect on the CYP mediated metabolic clearance of letrozole. However, chronic pretreatment of female rats with TAM appear to induce CYPs, but does not significantly impact the metabolic activities of the enzymes associated with the formation of the carbinol metabolite of letrozole.

Determinant role of membrane helices in K ATP channel gating

The ATP-sensitive K(+) (K(ATP)) channels couple chemical signals to cellular activity, in which the control of channel opening and closure (i.e., channel gating) is crucial. Transmembrane helices play an important role in channel gating. Here we report that the gating of Kir6.2, the core subunit of pancreatic and cardiac K(ATP) channels, can be switched by manipulating the interaction between two residues located in transmembrane domains (TM) 1 and 2 of the channel protein. The Kir6.2 channel is gated by ATP and proton, which inhibit and activate the channel, respectively. The channel gating involves two residues, namely, Thr71 and Cys166, located at the interface of the TM1 and TM2. Creation of electrostatic attraction between these sites reverses the channel gating, which makes the ATP an activator and proton an inhibitor of the channel. Electrostatic repulsion with two acidic residues retains or even enhances the wild-type channel gating. A similar switch of the pH-dependent channel gating was observed in the Kir2.1 channel, which is normally pH- insensitive. Thus, the manner in which the TM1 and TM2 helices interact appears to determine whether the channels are open or closed following ligand binding.

A threonine residue (Thr71) at the intracellular end of the M1 helix plays a critical role in the gating of Kir6.2 channels by intracellular ATP and protons

ATP-sensitive K+ (K(ATP)) channels are known to be gated by several intracellular molecules, but the gating mechanisms remain unclear. To understand the relationship of channel gating to ligand binding, we studied Kir6.2 channel gating by ATP and protons, which inhibit and activate the channel, respectively. We have previously shown that a threonine residue (Thr71) is critical for the pH sensitivity of Kir6.2 channel. If this site is involved in channel gating rather than ligand binding, it should affect channel gating by both ATP and proton. To test this hypothesis we performed a mutation analysis. Site-specific mutations of Thr71 to a bulky residue reduced the ATP sensitivity by >100-fold and eliminated the pH sensitivity. Single-channel activity of these mutants was stabilized at the open state with no detectable rundown. Mutations to a small amino acid had little effect on the ATP and pH sensitivities. Mutations to intermediate amino acids reduced but did not abolish the ATP and pH sensitivities. Hydrophobicity is not critical, as both polar and nonpolar amino acids are found in each group. Mutation to a positively charged lysine markedly exacerbated the pH- but not ATP-sensitivity, whereas mutation to glutamate moderately reduced ATP and pH sensitivities. These results indicate that the residue mass is critical for Kir6.2 channel gating, a mass that should be below 120 daltons with no charge. The existence of such a site as Thr71 involved in channel gating by both ATP and proton suggests that channel gating in the K(ATP) channel likely is separate from ligand binding.

Requirement of multiple protein domains and residues for gating K(ATP) channels by intracellular pH

ATP-sensitive K(+) channels (K(ATP)) are regulated by pH in addition to ATP, ADP, and phospholipids. In the study we found evidence for the molecular basis of gating the cloned K(ATP) by intracellular protons. Systematic constructions of chimerical Kir6.2-Kir1.1 channels indicated that full pH sensitivity required the N terminus, C terminus, and M2 region. Three amino acid residues were identified in these protein domains, which are Thr-71 in the N terminus, Cys-166 in the M2 region, and His-175 in the C terminus. Mutation of any of them to their counterpart residues in Kir1.1 was sufficient to completely eliminate the pH sensitivity. Creation of these residues rendered the mutant channels clear pH-dependent activation. Thus, critical players in gating K(ATP) by protons are demonstrated. The pH sensitivity enables the K(ATP) to regulate cell excitability in a number of physiological and pathophysiological conditions when pH is low but ATP concentration is normal.

Cloning of rabbit alpha(1b)-adrenoceptor and pharmacological comparison of alpha(1a)-, alpha(1b)- and alpha(1d)-adrenoceptors in rabbit

We have isolated a cDNA clone of the rabbit alpha(1b)-adrenoceptor which has an open reading frame of 1557 nucleotides encoding a protein of 518 amino acids. The sequence shows higher identity to those of hamster, human, and rat alpha(1b)-adrenoceptors than to those of rabbit alpha(1a)- and alpha(1d)-adrenoceptors. The pharmacological binding properties of this clone expressed in Cos-7 cells showed a characteristic profile as alpha(1b)-adrenoceptor; high affinity for prazosin (pK(i)=10.3), relatively high affinity for tamsulosin (9.5) and low affinity for (-)-(R)-1-(3-hydroxypropyl)-5-[2-[[2-[2-(2,2, 2-trifluoroethoxy)phenoxy]ethyl]amino]propyl]indoline-7-carboxamid e (KMD3213) (8.5), 2-(2,6-dimethoxy-phenoxyethyl)-aminomethyl-1, 4-benzodioxane hydrochloride (WB4101) (8.7), and 8-[2-[4-(2-methoxy-phenyl)-L-piperazinyl]-8-azaspiro[4,5]decane-7, 9-dione dihydrochloride (BMY7378) (7.3). We have compared the levels of mRNA expression of three alpha(1)-adrenoceptor subtypes in rabbit tissues using the competitive reverse transcription/polymerase chain reaction (RT/PCR) assay. In most rabbit tissues except heart, alpha(1a)-adrenoceptor mRNA was expressed 10 folds more than the other two subtypes. However, binding experiments with [3H]prazosin and [3H]KMD3213 in rabbit tissues revealed a poor relationship between binding density and mRNA level. Especially, alpha(1b) binding sites were exclusively predominant in spleen, whereas the alpha(1b) subtype was minor at the mRNA level. These results indicate a high identity of structural and pharmacological profiles of three distinct alpha(1)-adrenoceptor subtypes between rabbit and other species, but there are species differences in their distribution.

[Usefulness of galea suturing method for scalp closure]

A method for scalp closure to prevent alopecia along a suture line is described. Only the galea is sutured. By tacking a sufficient width of the galea on both sides with an absorbable suture material, the sutured wound forms a ridge. The outer layer is then closed with skin staples to keep the blood circulation undisturbed. This procedure contrasts with the traditional method in which the galea is sutured with the overlying subcutaneous tissue and consequently the hair follicles are strangled. By adopting the method of suturing the galea, development of alopecia along a suture line has been effectively prevented and scarring has become less conspicuous.

Chemical, metabolic and immunological characterization of gangliosides of human glioma cells

The patterns of ganglioside profiles were studied in 10 human glioma and one melanoma cell lines. Ganglio-series gangliosides, GM3 (NeuAc alpha2-3Gal beta1-4Glc beta1-Cer) and GM2 (GalNAc beta 1-4 (NeuAc alpha2-3)Gal beta1-4Glc beta 1-1Cer), and a neolacto-series ganglioside, sialylparagloboside (SPG) (NeuAc alpha 2-3Gal beta1-4GlcNAc beta1-3Gal beta1-4Glc beta1-1Cer), were the predominant constituents. The activities of the two key enzymes, GM3 synthetase and lactotriaosyl ceramide (Lc3Cer) synthetase, alone did not account for the ganglioside profile. Metabolic labeling with the use of [3H]glucosamine-HCl showed more pronounced difference in the synthetic rate of each ganglioside type, in which GM2 was the most strongly labeled in 7 out of the 10 glioma cell lines. On quantifying the chemical content of GM3 and GM2, the GM3/GM2 molar ratio of above 2.0 was arbitrarily classified into GM3 dominant type (KG-1C and Mewo); the ratio below 0.5 was designated as GM2 dominant type (H4, U138MG, U373MG, T98G and A172); and the ratio between 0.5 and 2.0 was regarded as GM3 and GM2-co-dominant type (U87MG, Hs683, SW1088 and U118MG). Subsequently, the capabilities of the antibody binding to these gangliosides were examined in native forms in the cell membrane and in chemically-isolated forms. The intensity of reaction against chemically isolated GM3 and GM2 gangliosides was dependent on the quantity, and GM2 was more reactive than GM3; however, the reactivities on the cell surface did not correlate with the chemical content indicating other factors to influence their immunoreactivities.

[Effects of basic fibroblast growth factor on anoxia/reoxygenation injury of rat neonatal cardiomyocytes]

The effects of basic fibroblast growth factor (bFGF) on anoxia/reoxygenation (A/R) injury and protein kinase C (PKC) activity were studied on a model of A/R injury of neonatal rat cardiomyocytes to investigate the possibility of its using as a substrate for pharmacological preconditioning. The data indicated that bFGF improved the viability of cardiomyocytes, lowered the deplection of ATP and leakage of intracellular lactate dehydrogenase (LDH) in a concentration-dependent manner. PKC inhibitor, H7, completely abolished the protective effects. It was also found that bFGF directely activated PKC in cardiomyocytes in a time course similar to that in hypoxic preconditioning. The data suggested that the protective effect of bFGF on cardiomyocyte A/R injury might be mediated by PKC.

Cell density regulates crypticity of GM3 ganglioside on human glioma cells

Human glioma cell line KG-1C contains GM3 ganglioside as its sole glycolipid. The degree of M2590 antibody binding to GM3 was found to be regulated by the cell density; the percentage of positive cells in FACS analysis decreased from approximately 20% to close to none as the cells increased their density from sparse to confluent. The contents of GM3 with different cell densities were consistent, being more than 0.4 micromol/g of the cellular weight, which was high enough to be recognized by the antibody. Trypsin treatment of the cells did not increase antibody reactivity. The extracted GM3 retained its antigenicity, being intensely stained with M2590 on a TLC plate; there was no change in chromatographic mobility either, indicating no modification of its chemical structure. The fluorescent microscope disclosed scattered dot-like staining of GM3, particularly at the periphery of the cells. We were able to expose cryptic GM3 fully within 12 h by dispersion of the cells to a sparse density. Surface labeling of GM3 with the use of limited sodium periodate oxidation of sialylated residue equally labeled GM3 either from the confluent cells or the sparse cells. Disassembly of actin filaments with cytochalasin B (10 microM) partially exposed cryptic GM3 of confluent cells, indicating reversibility of the crypticity. All together, the results indicate that cryptic GM3 actually exists on the cell surface, hidden from the surface not by other molecules but by other mechanisms associated with the cellular architecture. We are beginning to explore the possibility of selective localization of GM3 in small caves or folds of the cell membrane produced upon cell-to-cell contact.

[Protective effects of methanolic extract of Oenanthe stolonifera (Roxb.) Wall. ex DC. on myocardial injury induced by ischemia and reperfusion in rats]

The methanolic extract Oenanthe stoloni fera iv, pretreatment can significantly prevent the arrhythmias induced by myocardial ischemia and reduce the myocardial infarct size in rats. It can also markedly prevent myocardial ischemia and reperfusion-induced arrhythmias. In addition, the methanolic extract of Oenanthe stoloni fera (100 mg/kg i.v.) helps significantly to decrease the MDA content and preserve the SOD activity in plasma.

[Chemical constituents of Ledebouriella seseloides Wolff]

Eleven compounds were isolated from the methanolic extraction of the radix of Ledebouriella seseloides. They were identified as beta-sitosterol, bergapten, hamaudol, daucosterine sec-O-glucosylhamaudol, 5-O-methylvisamminol, cimifugin, sucrose, 4-O-beta-glucopyranosyl-5-O-methyl-visamminol, prim-O-glucosylcimifugin and mannitol by physico-chemical constants and spectroscopic analysis.