The extracellular calcium-sensing receptor is expressed in rat microglia and modulates an outward K+ channel

The calcium-sensing receptor (CaR) is a G protein-coupled receptor that "senses" extracellular calcium ions (Ca2+o) as an extracellular first messenger. In this report, we have shown that the CaR is expressed in primary cultures of microglial cells derived from rat brain as assessed by RT-PCR using four CaR-specific primer pairs followed by sequencing of the amplified products, by northern blot analysis using a CaR-specific probe, as well as by immunocytochemistry and western analysis utilizing a specific polyclonal anti-CaR antiserum. In addition, raising Ca2+o from 0.75 to 3.0 mM or addition of the polycationic CaR agonist neomycin or a "calcimimetic" CaR activator (R-467; NPS Pharmaceuticals) increased the open state probability (Po) of a Ca(+)-activated K+ channel having a unitary conductance of 84+/-4 pS, indicating that the channel is modulated by the CaR. Therefore, our data strongly suggest that a functional CaR is expressed in cultured rat microglia, similar to that in parathyroid gland and kidney, which could potentially play an important role(s) in regulating microglial function.

Photopolarimetric measurement of single, intact pulp fibers by mueller matrix imaging polarimetry

A method based on Mueller matrix polarimetry is developed and demonstrated for determining the fibril angle and relative phase retardation of single, intact pulp fibers. The method permits quantitative and nondestructive determination of these parameters from measurements at one wavelength without any fiber alignment. The Mueller matrix of a pulp fiber and its relationship with the fibril angle and phase retardation are described. A nonmodulation method for determining the Mueller matrix is then proposed that is based on a set of intensity data registered by a single detector. Measurements were carried out with single pulp fibers as samples to test the theoretical prediction. The test measurements and results are described and presented.

[Timing of vitrectomy for proliferative diabetic retinopathy in cases with type II diabetes mellitus]

OBJECTIVE

To determine the timing of vitrectomy for proliferative diabetic retinopathy with severe vitreous hemorrhage, retinal traction and even tractional detachment resulted from fibrovascular membranes in type II diabetes mellitus.

METHODS

According to the preoperative duration of vitreous hemorrhage and severity of diabetic retinopathy, 78 eyes of 64 cases having undergone vitrectomy were divided into 2 groups for the comparison of postoperative visual acuity.

RESULTS

After 9 months of follow-up, in the group with preoperative vitreous hemorrhage of <or= 6 months' duration 42.1% of cases had visual acuity of >or= 0.3, while in the group with preoperative vitreous hemorrhage of > 6 months' duration 5.3% of cases reached such a level (P < 0.01). After one year, in the group with preoperative vitreous hemorrhage of <or= 6 months 35.7% of cases had visual acuity of >or= 0.5, while in the group with preoperative vitreous hemorrhages of > 6 months' duration, 7.1% (P < 0.05). In the group of vitreous hemorrhage with or without local tractional retinal detachment, 35.7% had visual acuity of >or= 0.5, while in the group with large area of tractional retinal detachment, 16.7% (P < 0.05).

CONCLUSION

Earlier vitrectomy is preferable for type II diabetes mellitus with vitreous hemorrhage, and the operative treatment should not be abandoned for the patients with vitreous hemorrhage of longer duration and severe tractional retinal detachment.

Nontargeted stable integration of recombinant adeno-associated virus into human leukemia and lymphoma cell lines as evaluated by fluorescence in situ hybridization

A number of studies on human epithelial cells of varying origin have demonstrated integration of recombinant adeno-associated virus (AAV) vectors into a variety of chromosomes compared with the site-specific integration on chromosome 19 predominantly observed for wild-type (wt) AAV. We have constructed a recombinant AAV (rAAV) vector and tested the integration into hematopoietic cells, using the human acute myeloid leukemia cell line AML5 and the human non-Hodgkin's lymphoma cell line OCI-LY18 as targets. The integration sites were visualized by fluorescence in situ hybridization (FISH). Positive signals were observed for chromosomes 1, 2, 3, 8, 14, 15, 19, and Y. The majority of cells demonstrated integration into one specific site. A minority showed simultaneous integration into more than one chromosome. The frequency of observed integrations was not uniformly distributed among chromosomes; for instance, in AML5 chromosome 2 seemed to be favored. Colony-derived AML5 clones bore unique integration patterns indicating successful transduction of clonogenic progenitor cells with high proliferative potential. The integration was stable and observed for more than 12 months after transduction. FISH has been shown to be a powerful tool for detailed analyses of rAAV integration patterns and can be used to evaluate targets and transduction conditions.

Two Arabidopsis mutants that overproduce ethylene are affected in the posttranscriptional regulation of 1-aminocyclopropane-1-carboxylic acid synthase

The Arabidopsis mutants eto1 (ethylene overproducer) and eto3 produce elevated levels of ethylene as etiolated seedlings. Ethylene production in these seedlings peaks at 60 to 96 h, and then declines back to almost wild-type levels. Ethylene overproduction in eto1 and eto3 is limited mainly to etiolated seedlings; light-grown seedlings and various adult tissues produce close to wild-type amounts of ethylene. Several compounds that induce ethylene biosynthesis in wild-type, etiolated seedlings through distinct 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) isoforms were found to act synergistically with eto1 and eto3, as did the ethylene-insensitive mutation etr1 (ethylene resistant), which blocks feedback inhibition of biosynthesis. ACS activity, the rate-limiting step of ethylene biosynthesis, was highly elevated in both eto1 and eto3 mutant seedlings, even though RNA gel-blot analysis demonstrated that the steady-state level of ACS mRNA was not increased, including that of a novel Arabidopsis ACS gene that was identified. Measurements of the conversion of ACC to ethylene by intact seedlings indicated that the mutations did not affect conjugation of ACC or the activity of ACC oxidase, the final step of ethylene biosynthesis. Taken together, these data suggest that the eto1 and eto3 mutations elevate ethylene biosynthesis by affecting the posttranscriptional regulation of ACS.

Expression of midkine in the early stage of carcinogenesis in human colorectal cancer

It has been suggested that a heparin-binding growth factor, midkine (MK), plays an important role in carcinogenesis because of its frequent overexpression in various malignant tumours. To clarify whether or not MK contributes to the early stage of carcinogenesis, we examined the status of MK mRNA in 20 adenomas with moderate- and severe-grade dysplasia, 28 carcinomas and 28 corresponding normal tissues, by means of Northern blotting. The MK expression level was significantly more elevated in adenomas than in normal tissues (P < 0.001, unpaired Student's t-test). A difference was also observed between carcinomas and the corresponding normal tissues (P < 0.04, paired Student's t-test). Moreover, MK immunostaining was positive in the adenomas with moderate- and severe-grade dysplasia and in the carcinomas, but not in mild-grade dysplasia or in normal tissues. These findings were in line with those on Western blotting. In three patients with both adenomas with moderate- or severe-grade dysplasia and carcinomas, elevated MK expression was observed in the neoplastic lesions. This is the first report of the association of elevated MK expression with the early stage of carcinogenesis in humans.

[Application of perfluorocarbon liquids in vitrectomy]

OBJECTIVE

To popularize the use of perfluorocarbon liquids in vitrectomy and increase the cure rate of complicated retinal detachment.

METHODS

The clinical application of perfluorocarbon liquids during vitrectomy for complicated retinal detachment of 76 eyes has been summarized. The postoperative retinal detachment rate and visual acuity of 54 eyes with retinal detachment complicated with severe proliferative vitreoretinopathy and 11 eyes with giant retinal tears were analyzed statistically.

RESULTS

The retina was reattached in 71 of 76 eyes (93.4%), in 50 of 54 eyes with severe PVR (92.6%) and in 9 of 11 eyes with giant retinal tears (81.8%). The postoperative visual acuity was above 0.02 in 69 eyes (90.8%) and > 0.1 in 29 eyes (38.2%) of 76 eyes, respectively in 50 (92.6%) and 18 (33.3%) of 54 eyes with severe PVR and 9 (81.8%) and 4 (36.4%) of 11 eyes with giant retinal tears. During surgery, perfluorocarbon entered through tears into subretinal space and was removed immediately in 6 of 76 eyes. Postoperatively, a small portion of residual perfluorocarbon liquid was observed in the anterior chamber of 17 of 76 eyes and in the vitreous cavity of 2 phakic eyes of 76 eyes, no complication was observed except one case with mild corneal opacification.

CONCLUSION

Perfluorocarbon liquids are the useful adjunct to the hydrokinetic manipulation in vitreous surgery.

Analysis of trace atrazine and simazine in environmental samples by liquid chromatography-fluorescence detection with pre-column derivatization reaction

Coupled with off-line extraction, a pre-column derivatization liquid chromatographic fluorescence detection (LC-FL) procedure was developed for the determination of atrazine and simazine in soil, crop and water samples. Concentrations in real samples were expected to be at or below the low ng/g level, which requires pre-concentration of analytes and improved detection. 4-(2-Phthalimidyl) benzoyl chloride (PIB-Cl) was used as a pre-column derivation reagent for high-performance liquid chromatography. The clean-up and second-time concentration procedures, which were indispensable in the conventional analytical methods for soil and crop analysis because of the complexity of the samples, were replaced by a derivatization reaction between PIB-Cl and the analytes. The fluorescent and ultraviolet characteristics of the derivatives were investigated. The derivatization reaction and chromatographic separation conditions were optimized systematically. Detection limits of 1.2 ng/g for atrazine and 1.1 ng/g for simazine were obtained with recoveries of 84-95% for environmental samples. On the basis of practical application to five soil and five crop samples, the LC-FL method was compared with the conventional GC-MS method.

[Surgical treatment of perplexing renal cell carcinoma]

OBJECTIVE

To summarize the experience of surgical treatment of perplexing renal cell carcinoma in order to increase survival rate.

METHODS

From 1987 through 1996, 20 patients with perplexing renal cell carcinoma were surgically treated. There were 3 patients in stage I, 9 in stage II, and 8 in stage III. The operative proceduce was described and the follow-up results were analysed.

RESULTS

Among 20 patients, 18 were evaluable. The 1-, 3-, 5-year survival rate was 100%, 91.7% and 75% for stage I-II; 87.5%, 62.5% and 37.5% for stage III, respectively.

CONCLUSION

Radical nephrectomy is still effective for the patients with perplexing renal cell carcinoma.

A genetic locus susceptible to the overt proteinuria in BUF/Mna rat

The BUF/Mna (BUF) strain is a high-proteinuria line of rats, and virtually all rats develop overt proteinuria by the age of 20 weeks. Genetic analysis revealed that proteinuria susceptibility was determined principally by two autosomal recessive genes. These findings prompted us to perform genetic mapping of the genes. (BUF/Mna x WKY/NCrj) F1 x BUF/Mna backcross rats were raised and maintained for 40-60 weeks to detect proteinuria. DNAs were extracted from ears of these rats and were examined by linkage study with polymerase chain reaction (PCR) with 132 microsatellite markers. Fifty-three out of 167 rats developed proteinuria. DNAs of 51 out of these 53 rats showed homozygous BUF/BUF genotype in the D13Mgh4 and D13N1 markers located on Chromosome (Chr) 13. The D13Rat1, D13Mgh2, D13Rat13, D13Mgh3, Syt2, Ren, D13Rat25, D13Mit2, D13Mgh5, and D13N2 markers located on the chromosome also showed statistically significant linkage to the development of proteinuria, whereas the other 110 markers showed no linkage. Here we report that a proteinuria-susceptible gene, Pur1, resides on a region flanked by the loci D13Mgh3 and D13Mgh4 on Chr 13.

Induction of immune tolerance in adult rabbits undergoing heterotopic cardiac transplantation

OBJECTIVE

To induce experimental immune tolerance in rabbits and observe its effects on heterotopic cardiac transplantation.

METHODS

Donor's splenic lymphocytes pretreated with platinum metal chelator were injected into the recipient's mesenteric-portal vein. Cyclosporin A was perfused through the donor's heart.

RESULTS

The injection of donor's splenic lymphocytes before transplantation could significantly prolong the survival time of the heterotopically transplanted heart. The effect of two injections was better than that of one. Radioactive tracer studies showed that the 99mTc-HMPAO tagged lymphocytes injected into the recipient rabbit were later concentrated in the liver, though initially they were distributed in multiple organs. The induced immune tolerance was antigen-specific, and it neither affect the other immune functions of the lymphatic system prominently nor exert any harmful effect on the recipient's liver and renal functions. The perfusion of cyclosporin A through the donor heart could block the glycosyl groups, such as D-glucose, D-mannose or N-acetyl-galactosamine on the surface of the myocardial cells, thus might change the antigenic expression, effectively preventing rejection of the graft by the host, and might be considered as a new method to block graft rejection in cardiac transplantation. The combined use of the above-mentioned two methods acted on both the host and the donor, thus reducing the exposed antigens on the donor organ as well as the immune reaction against the donor antigens, and resulting in synergistic effect in inducing immune tolerance in adult rabbits, and resulting in relatively long-term survival of transplanted hearts.

CONCLUSION

This report may provide the experimental basis for inducing immune tolerance in clinical transplantation.

[Sequencing of a beta-amylase gene from Bacillus firmus]

The gene encoding a beta-amylase from Bacillus firmus 725 was sequenced. The sequenced DNA of 2012 bp contains one open reading frame of 1406 nucleotides without a translation stop codon. The deduced amino acid sequence homology with those known bacterial and some plant beta-amylase was 98% for Bacillus polymyxa 72, 98% for Bacillus polymyxa ATCC8523, 82% for Bacillus circulans, 54% for Clostridium thermosulfurogenes, 49% for Bacillus cereus BQ10-S1, 50% for Bacillus cereus var. mycoides, 36% for barley, and 36% for soybean Eleven well-conserved regions were found among the amino acid sequences of the nine beta-amylases.

Improved free musculocutaneous flap survival with induction of heat shock protein

The cellular response to a wide variety of stresses results in the synthesis of a family of stress response proteins termed heat shock proteins. Recent studies have demonstrated that heat shock proteins produced in response to an initial stress seem to protect against subsequent unrelated stresses. Importantly, hyperthermia-induced heat shock proteins provided protection from ischemia/reperfusion injury in several organ transplantation models. We hypothesized that free musculocutaneous flap survival could be improved by enhancing the flap's tolerance to relative ischemia by the prior induction of heat shock proteins. Accordingly, we determined the heat shock protein response in skin and muscle after systemic or local heating and examined the effect on free musculocutaneous flap survival in a rat model. Free musculocutaneous flaps incorporating thigh adductor muscles and a 2 x 6-cm2 skin paddle were transplanted to the ipsilateral groin in three groups of male Wistar rats. Systemically heated rats (n = 6) were anesthetized and incubated for 30 minutes at 42 degrees C 6 hours before free musculocutaneous tissue transfer. Locally heated rats (n = 6) were anesthetized, and their donor site anterior thigh was placed for 30 minutes on a heating block set at 44 degrees C 6 hours before free tissue transfer. Control rats (n = 5) did not have heating pretreatment but underwent identical anesthesia. Animals were sacrificed on postoperative day 3, at which time skin loss (cm2) and muscle viability, quantified by nitroblue tetrazolium staining time, were assessed in a blinded fashion. The skin and muscle from the free flap were analyzed for HSP72 mRNA and protein using quantitative Northern and Western blot techniques. All free musculocutaneous flaps were viable. However, the locally and systemically heated rats demonstrated a marked improvement of skin survival, which correlated with increased skin levels of HSP72. There were no differences in nitroblue tetrazolium muscle staining times or muscle levels of HSP72 among the three groups. These findings suggest that prior heat-induced heat shock proteins result in improvement in musculocutaneous flap survival, which may have direct clinical applications, especially in high-risk patients.

1H/27Al TRAPDOR NMR studies on aluminum species in dealuminated zeolites

Aluminum species in several dealuminated zeolites (ultrastable HY, HZSM-5 and mordenite) were investigated in detail by means of the newly introduced 1H/27Al TRAPDOR method in combination with 27Al MAS NMR, and the quadrupole coupling constants (Q[CC]s) for aluminum atoms associated with these species were obtained. A signal at ca. 6.8 ppm, due to water molecules adsorbed on Lewis acid sites, was observed in the 1H MAS spectra for all the three zeolites. The TRAPDOR NMR provides direct evidence that there is a strong interaction between the adsorbed water molecules and the aluminum atoms of the Lewis-acid sites. The Q(CC) values for this aluminum species of 8.3, 6.7 and 11.3 MHz were determined from the TRAPDOR profiles for the ultrastable HY, HZSM-5 and mordenite zeolites, respectively. The Q(CC)s calculated from the TRAPDOR curves are usually larger than 10 MHz for both Bronsted-acid sites (SiOHAI) and non-framework aluminum species in the three zeolites. Three narrow peaks at 54, 30 and 0 ppm are separately superimposed on a broad hump in the 27Al MAS spectra of the three dehydrated zeolites, while the latter is associated with the 'NMR invisible' Al. The NMR experimental results suggest that the three kinds of aluminum species (non-framework aluminum species, Bronsted- and Lewis-acid sites) are all responsible for the resonance of the broad hump in dehydrated zeolites, which makes it difficult to explain the 27Al MAS spectra. Fortunately, the TRAPDOR NMR provides a direct method for individually studying different aluminum species with large Q(CC)s via their dipolar coupling to nearby proton nuclei.

Three-dimensional maximum-quantum correlation HMQC NMR spectroscopy (3D MAXY-HMQC)

The extension of two-dimensional maximum-quantum correlation spectroscopy (2D MAXY NMR), which can be used to simplify complex NMR spectra, to three dimensions (3D) is described. A new pulse sequence for 3D MAXY-HMQC is presented and exemplified using the steroid drug dexamethasone. The sensitivity and coherence transfer efficiency of the MAXY NMR approach has also been assessed in relation to other HMQC- and HSQC-based 3D methods. Copyright 1997 Academic Press. Copyright 1997Academic Press

High-field (9.4 T)(1)H magnetic resonance microscopy of mouse brain

The FLASH and STEAM pulse sequences were used to perform the microimaging and localized spectroscopy of brain of living and dead mice, respectively. The phase-shift presaturation approach was used to suppress water NMR signal. The experimental results show that the differences in localized spectra and MR images of brain between live and dead mice can be observed by means of magnetic resonance microscopy.

Targeted inactivation of alphai2 or alphai3 disrupts activation of the cardiac muscarinic K+ channel, IK+Ach, in intact cells

Cardiac muscarinic receptors activate an inwardly rectifying K+ channel, IK+Ach, via pertussis toxin (PT)-sensitive heterotrimeric G proteins (in heart Gi2, Gi3, or Go). We have used embryonic stem cell (ES cell)-derived cardiocytes with targeted inactivations of specific PT-sensitive alpha subunits to determine which G proteins are required for receptor-mediated regulation of IK+Ach in intact cells. The muscarinic agonist carbachol increased IK+Ach activity in ES cell-derived cardiocytes from wild-type cells, in cells lacking alphao, and in cells lacking the PT-insensitive G protein alphaq. In cells with targeted inactivation of alphai2 or alphai3, channel activation by both carbachol and adenosine was blocked. Carbachol-induced channel activation was restored in the alphai2- and alphai3-null cells by reexpressing the previously targeted gene and guanosine 5'-[gamma-thio] triphosphate was able to fully activate IK+Ach in excised membranes patches from these mutants. In contrast, negative chronotropic responses to both carbachol and adenosine were preserved in cells lacking alphai2 or alphai3. Our results show that expression of two specific PT-sensitive alpha subunits (alphai2 and alphai3 but not alphao) is required for normal agonist-dependent activation of IK+Ach and suggest that both alphai2- and alphai3-containing heterotrimeric G proteins may be involved in the signaling process. Also the generation of negative chronotropic responses to muscarinic or adenosine receptor agonists do not require activation of IK+Ach or the expression of alphai2 or alphai3.

Calcium-sensing receptor in the rat hippocampus: a developmental study

The extracellular Ca2+ (Ca2+(o))-sensing receptor (CaR) plays a key role in maintaining near constancy of Ca2+(o) in mammals through its presence in parathyroid gland and kidney. The CaR is also present in brain, and although its role(s) in the brain is not known, it is possible that small changes in Ca2+(o) modify essential physiological and pathological processes, since calcium is crucial for numerous neuronal functions. Northern analysis has revealed that the CaR mRNA is present in hippocampus and several other regions of the brain. The hippocampus is an important site for learning and memory, but the relevance of the CaR to these processes is unknown. Long-term potentiation (LTP), a putative in vitro analog of memory, can only be induced after 7-10 days postnatally in rat hippocampus. Therefore, in the present study we determined the time course for the developmental expression of the CaR in rat hippocampus to assess its relationship to the development of other important hippocampal functions, such as the capacity for induction of LTP. Northern and Western analyses showed that CaR mRNA and protein were expressed at low levels at 5 days postnatally but then increased markedly at 10 days. A high level of receptor expression, due primarily to an increase in a 7.5 kb transcript, persisted until 30 days, when it gradually decreased by 3-fold to reach the adult level of expression. In situ hybridization histochemistry and immunohistochemistry revealed CaR mRNA and protein in pyramidal cells of all the layers of hippocampus and in granule cells of the dentate gyrus. The results show that CaR expression rises at a time when LTP can first be induced in hippocampus and persists at high levels during the time when brain development is proceeding most rapidly. Further studies are needed to determine the role of the CaR in the development of important aspects of the function of hippocampus and other regions of brain, including LTP.

Expression of extracellular calcium-sensing receptor by human lens epithelial cells

The extracellular calcium-sensing receptor (CaR) confers the capacity to sense small changes in the extracellular Ca2+ concentration (Ca2+o) not only upon cells involved in maintaining systemic Ca2+ homeostasis but also upon those not directly involved in this process. Since high Ca2+o is known to affect various physiological processes in lens epithelium both in health and in disease states (e.g., the formation of cataracts in hypocalcemic states), we investigated the expression and function of the CaR in these cells. By RT-PCR and immunocytochemistry the CaR is expressed in human lens epithelial cells in culture. In addition, the open state probability of a Ca(2+)-activated potassium (K+) channel with a conductance of 82 +/- 3 pS is significantly increased by elevating Ca2+o to 3.0 mM or by application of 100 microM neomycin, both effective CaR agonists. Therefore, our data suggest that human lens-epithelial cells express the CaR, which may be functionally linked to Ca(2+)-activated K+ channels and, perhaps, to other ion channels involved in ionic homeostasis in the lens.

Cao-sensing receptor (CaR)-mediated activation of K+ channels is blunted in CaR gene-deficient mouse neurons

The extracellular Ca2+ (Cao)-sensing receptor (CaR) is expressed in hippocampus and other brain regions, suggesting that it could mediate some of the well recognized but poorly understood direct actions of Cao on neuronal function. This study presents evidence that the CaR is functionally coupled to Ca(2+)-activated K+ channels. The effects of CaR agonists on these channels in neurons from wild type (WT) and CaR-deficient (CaR -/-) mice were compared. Neomycin (100 mM) and elevation of Cao from 0.5 to 3 mM significantly increased the probability of channel opening (Po) in neurons from WT but not in those from CaR -/- mice. Thus the CaR activates neuronal K+ channels and could potentially inhibit neuronal excitability and neurotransmission via membrane repolarization.

Dynamic nuclear polarization of nitrogen-15 in benzamide

A 15N dynamic nuclear polarization (DNP) experiment is reported in which a 15N DNP enhancement factor of approximately 2.6 x 10(2) is obtained on free radical doped samples of 99% 15N labeled benzamide. The free radicals BDPA (1:1 complex of alpha, gamma-bisdiphenylene-beta-phenylallyl with benzene) and DPPH (2,2-Di(4-tert-octylphenyl)-1-picrylhydrazyl) are used as dopants and the spin relaxation effects of adding these dopants are studied by means of changes in proton and nitrogen T1 values of the samples. The combination in solids of a very low natural abundance, 0.37%, a small gyromagnetic ratio, and a long spin-lattice relaxation time for 15N nuclei create severe sensitivity problems that, in large part, are ameliorated by the signal enhancement observed in the 15N DNP experiment on samples containing free electrons.

[Changes of calcium transport in rat liver nuclei during sepsis]

Calcium transport changes in rat liver nuclei were observed on the model of early sepsis (9 h after operation of cecal ligation and puncture). Calcium content in hepatocytes and nuclei were significantly increased by 20% and 36% respectively (P < 0.05) during sepsis. The activity of Ca(2+)-ATPase in hepatocytic nuclei was increased by 94% (P < 0.01) and 45Ca2+ transport accelerated by 32% (P < 0.01). There was a positive correlation between nuclear 45Ca2+ transport and nuclear Ca(2+)-ATPase activity (r = 0.914, P < 0.01). Calmodulin stimulated the activity of nuclear Ca(2+)-ATPase and 45Ca2+ transport; while calmodulin inhibitor trifluoperazine exerted an opposite effect. The above results suggest that liver nuclear calcium transport is strengthened during early sepsis as a result of changes of Ca(2+)-ATPase activity.

Amyloid-beta proteins activate Ca(2+)-permeable channels through calcium-sensing receptors

The amyloid-beta peptides (A beta) are produced in excess in Alzheimer's disease (AD) and may contribute to neuronal dysfunction and degeneration. This study provides strong evidence for a novel cellular target for the actions of A beta, the phospholipase C-coupled, extracellular Ca(2+)-sensing receptor (CaR). We demonstrate that A beta(s) produce a CaR-mediated activation of a Ca(2+)-permeable, nonselective cation channel (NCC), probably via elevation in cytosolic Ca2+ (Cai), in cultured hippocampal pyramidal neurons from normal rats and from wild type mice but not those from mice with targeted disruption of the CaR gene (CaR -/-). A beta(s) also activate NCC in CaR-transfected but not in nontransfected human embryonic kidney (HEK293) cells. Thus aggregates of A beta deposited on hippocampal neurons in AD could appropriately activate the CaR, stimulating Ca(2+)-permeable channels and causing sustained elevation of Cai with resultant neuronal dysfunction.

1H MAS and 1H[23Na] double resonance NMR studies on the modification of surface hydroxyl groups of gamma-alumina by sodium

The modification of surface hydroxyl groups with sodium in a series of Na2CO3-gamma-Al2O3 catalysts was investigated as a function of both the Na2CO3 loading and the calcination temperature by means of 1H magic angle spinning (MAS) and 1H(23Na) spin-echo double resonance NMR techniques. The 1H NMR experiments revealed that sodium ions are homogeneously distributed over the alumina surface and closely coordinated with the surface hydroxyl groups. In the catalysts calcined at 250 degrees C, the acidic hydroxyl groups (with a chemical shift of 2.0 ppm) are preferentially associated with sodium ions at low Na2CO3 coverages (5 and 10%), while both the acidic and the basic (0 ppm) hydroxyl groups are accessible for sodium ions at high coverages (15 and 20%). The coordination causes a low-field shift of about 2 ppm in the 1H MAS spectra, and a broad signal at 4.5 ppm appears. It is interesting that the 4.5 ppm signal is completely suppressed in the 1H(23Na) MAS experiments, providing direct evidence that a strong interaction exists between adsorbed sodium ions and the surface hydroxyl groups. Increasing the calcination temperature to 450 degrees C results in preferential removal of the acidic hydroxyl groups, and only the most basic hydroxyl groups remain when the calcination temperature is raised to 600 degrees C. This is attributed to the formation of the coordinated species. [formula: see text] which enhances the acidity of the surface hydroxyl groups and prompts their dehydroxylation, especially at high calcination temperature. Correlation of the 1H MAS NMR results and catalytic activity measurements indicates that the basic hydroxyl groups are essential for the carbonyl sulfide hydrolysis reaction.