(Ethanol)(2,3,7,8,12,13,17,18-octaethylporphinato)manganese(III) perchlorate

The crystal structure of [Mn(C36H44N4)(C2H6O)]ClO4 has been determined. The average Mn-Np bond distance is 1.997 (5) A and the axial Mn-O bond length is 2.145 (2) A. The manganese(III) ion has a displacement of 0.17 A from the mean plane of the 24-atom porphinato core.

A scintigraphic study on gastric emptying in patients with non-ulcer dyspepsia

Solid gastric emptying rates (GER) were determined with scintigraphic techniques in 20 patients with non-ulcer dyspepsia (NUD) and 9 healthy volunteers. GER were significantly decreased in NUD patients compared with controls, especially 45 min (P < 0.05), 60 and 90 min (P < 0.01) and 120 min (P < 0.05) after ingestion. In 13 out of 20 NUD patients who demonstrated lower GER, only 4 cases gave a lower GER at all stages throughout the determination, the other 9 showed their abnormal GER only after 60 min. In 3 cases who received repeated GER studies after cisapride therapy, 2 patients showed symptomatic relief accompanied by GER improvement. It is concluded that gastric emptying delay may be present with a high percentage in patients with non-ulcer dyspepsia. Scintigraphic gastric emptying test is a safe and reliable technique with good reproducibility. It may be helpful in quantitative study about gastric motion disorders.

Chloro(5,10,15,20-tetraphenylporphyrinato)manganese(III) with 4/m symmetry

The crystal structure of [Mn(TPP)Cl] in space group I4/m (where TPP is C44H28N4) has been determined. The unit cell contains two full molecules, with one eighth of a molecule unique. An out-of-plane model for the Mn atom was applied and all non-H atoms were refined anisotropically. The Mn--N distance is 2.002 (3) A, the axial Mn--Cl distance is 2.297 (15) A and the out-of-plane displacement of the Mn atom is 0.16 A. The possibility of a reverse-doming porphyrin core conformation is mentioned briefly.

Basic fibroblast growth factor selectively increases AMPA-receptor subunit GluR1 protein level and differentially modulates Ca2+ responses to AMPA and NMDA in hippocampal neurons

The excitatory neurotransmitter glutamate is believed to play important roles in development, synaptic plasticity, and neurodegenerative conditions. Recent studies have shown that neurotrophic factors can modulate neuronal excitability and survival and neurite outgrowth responses to glutamate, but the mechanisms are unknown. The present study tested the hypothesis that neurotrophic factors modulate responses to glutamate by affecting the expression of specific glutamate-receptor proteins. Exposure of cultured embryonic rat hippocampal cells to basic fibroblast growth factor (bFGF) resulted in a concentration-dependent increase in levels of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)-receptor subunit GluR1 protein as determined by western blot, dot-blot, and immunocytochemical analyses. In contrast, bFGF did not alter levels of GluP2/3, GluR4, or the NMDA-receptor subunit NR1. Nerve growth factor did not affect GluR1 levels. Calcium-imaging studies revealed that elevation of [Ca2+]i, resulting from selective AMPA-receptor activation, was enhanced in bFGF-pretreated neurons. On the other hand, [Ca2+]i responses to NMDA-receptor activation were suppressed in bFGF-treated neurons, consistent with previous studies showing that bFGF can protect neurons against NMDA toxicity. Moreover, neurons pretreated with bFGF were relatively resistant to the toxicities of glutamate and AMPA, both of which were shown to be mediated by NMDA receptors. These data suggest that differential regulation of the expression of specific glutamate-receptor subunits may be an important mechanism whereby neurotrophic factors modulate activity-dependent neuronal plasticity and vulnerability to excitotoxicity.

PDGFs protect hippocampal neurons against energy deprivation and oxidative injury: evidence for induction of antioxidant pathways

Platelet-derived growth factors (PDGFs) and PDGF receptors are expressed in brain, where their functions are largely unknown. We tested the hypothesis that PDGFs play a role in promoting the survival of neurons exposed to metabolic and oxidative insults. Exposure of rat and mouse hippocampal cell cultures to glucose-deficient medium or the hydroxyl radical-promoting agent FeSO4 resulted in progressive neuronal loss. Pretreatment of cultures with PDGF-AA or PDGF-BB resulted in highly significant attenuation of glucose deprivation- and FeSO4-induced neuronal degeneration. In each injury paradigm the neuroprotective actions of the PDGFs were concentration dependent (3-100 ng/ml). In the case of glucose deprivation, significant protection was seen when cells were exposed to PDGFs prior to, or up to 8 hr following, the onset of glucose deprivation. Pretreatment with PDGFs was required for protection against FeSO4-induced oxidative injury. Western blot and immunocytochemical analyses demonstrated that cultured embryonic hippocampal neurons expressed both PDGF alpha- and beta-receptors. PDGFs induced tyrosine phosphorylation of several proteins including a band at 180 kDa, the molecular weight of PDGF receptors. Induction of peroxide accumulation in neurons by FeSO4 was attenuated in cultures pretreated with PDGFs, suggesting that PDGFs enhanced cellular antioxidant mechanisms. Measurements of anti-oxidant enzyme activities in control and PDGF-treated cultures showed that both PDGF-AA and PDGF-BB increased both catalase and glutathione peroxidase activities, and PDGF-AA also increased superoxide dismutase activities. These findings suggest that PDGFs, which are widely expressed in brain and induced in response to injury, may play roles in protecting neurons against metabolic and oxidative insults.

Brain injury and tumor necrosis factors induce calbindin D-28k in astrocytes: evidence for a cytoprotective response

Calbindin is a 28 kDa calcium-binding protein expressed in restricted neuronal populations in the mammalian brain where it may play a role in protecting neurons against excitotoxic insults. Recent findings indicate that electrical activity and some neurotrophic factors can induce the expression of calbindin in neurons. We now report that brain injury, effected by systemic administration of the excitotoxin kainate or mechanical trauma, induces expression of calbindin in cells of the corpus callosum and subcortical white matter. Immunohistochemical analysis using antibodies to the astrocyte-specific proteins (glial fibrillary acidic protein and S-100 beta) established the identity of calbindin immunoreactive cells as astrocytes. Because brain injury is known to induce the expression of several neurotrophic factors and cytokines, we employed cultures of hippocampal and neocortical astrocytes to test the hypothesis that such factors can induce expression of calbindin in astrocytes. Tumor necrosis factors (TNF alpha and TNF beta), cytokines that are expressed in response to brain injury, induced the expression of calbindin in cultured rat hippocampal and neocortical astrocytes. Two neurotrophic factors, basic fibroblast growth factor and nerve growth factor, did not induce calbindin in astrocytes. TNF-treated, calbindin-expressing astrocytes were resistant to acidosis and calcium ionophore toxicity, suggesting that TNFs and calbindin may serve a cytoprotective role in astrocytes in the injured brain.

[Comparative study on pharmacological effects of various species of Pueraria]

Through comparative studies on the acute toxicity of four species of Pueraria, it was found that the toxicity of P. peduncularis was the highest, followed by P. lobata and P. omeiensis, and that of P. thomsonii was the lowest. The inhibitory effects of P. lobata, P. omeiensis and puerarin on the fever induced by 2,4-dinitrophenol in rats were very fast and significant, maintaining for about 8 hours, while the effect of P. thomsonii is relatively weak. As for influence upon the degrees of myocardiac ischemia induced by pituitrin, P. omeiensis appeared to be the most potent, and P. thomsonii the least one, while P. lobata and puerarin were intermediate between the above two. Summarily, the antipyretic and anti-myocardiac ischemia effects of P. lobata and P. omeiensis are stronger than those of P. thomsonii, and puerarin is one of their effective components.

Diaqua(5,10,15,20-tetraphenylporphinato)iron(III) Perchlorate, [Fe(C44H28N4)(H2O)2]ClO4

The crystal structure of a new crystal form of [Fe(TPP)(H2O)2]ClO4 has been determined. The asymmetric unit contains one molecule in a general position and a half molecule with required inversion symmetry. The two independent molecules have almost identical average values for the equatorial Fe-Np bond lengths [2.029 (4) and 2.028 (6) A], and the axial Fe-O bond lengths are 2.140 (2) and 2.121 (3) A for molecule 1 (in a general position) and 2.126 (2) A for molecule 2 (in a special position). A brief comparison of the core structure and hydrogen-bonding environment of this molecule with two other crystal forms is described.

Overtraining following intensified training with normal muscle glycogen

The purpose of this study was to determine if consumption of appropriate amounts of carbohydrate during a period of increased exercise training would protect the athletes from becoming overtrained. Eight male competitive cyclists were monitored and tested during three training periods: a) normal training (moderate intensity, long duration, 7 d, NORM); b) overtraining (high intensity training, 15 d, OVER); and c) recovery (minimal training, 6 d, REC). Throughout the training 160 g of liquid carbohydrate were consumed within the first 2 h after the daily exercise bout. Mean dietary intake (NORM = 13.7 +/- 1.6, OVER = 14.1 +/- 1.0 MJ.d-1) and carbohydrate percent (NORM = 64.0 +/- 2.1, OVER = 67.4 +/- 2.5%) were not different during the different training periods. Similarly, resting muscle glycogen levels were not different (NORM = 530.9 +/- 42.5, OVER = 571.2 +/- 27.5 mumol.g-1 dry weight). Five criteria were used to determine if overtraining occurred in a subject (decreased maximal workload, maximal heart rate, ratio of maximal lactate to rating of perceived exertion (HLa:RPE), and resting plasma cortisol levels, increased affirmative response to a daily questionnaire). All subjects met at least three of the five criteria and thus were classified as overtrained. Therefore, short-term overtraining may occur even when resting muscle glycogen levels are maintained.

(2,3,7,8,12,13,17,18-Octaethylporphinato)perchloratomanganese(III)

The crystal structure of [Mn(OEP)(OClO3)] (where OEP = C36H44N4) has been determined. The axial Mn-O bond length is 2.183 (2) A and the equatorial Mn-Np bond lengths have an average value of 2.000 (5) A. The molecules form weak dimers in the solid state with interring distances of 3.49 A and a lateral shift of 3.27 A. The compound is found to be isomorphous with the iron derivative [Fe(OEP)(OClO3)]. A brief comparison of the structural parameters for the two molecules is given.

[Anatomical study on the Riolan's anastomosis arch]

The Riolan's anastomosis arch is discussed on the basis of colon vessel constructions in 162 operations of the colonic interposition for esophageal substitution, and the materials reported in some journals. The Riolan's arch is not the marginal vessels of the flexura lienalis, because of its lower incidence (< 10%). We believe that the integrity of the arch is not responsible for the blood supply of the colon.

Three-dimensional ordered patterns by light interference

Based on numerical simulation it is found that three-dimensional periodic patterns with micrometer or submicrometer lattice constants, such as those with simple cubic, face-centered cubic, body-centered cubic, or body-centered tetragonal symmetry, can be formed by use of multiple laser beam interference. Changes in the number and angle of the incident beams result in different spatial patterns, whereas variation of the incident wavelength affects only the lattice constant of the patterns. Face-centered cubic and body-centered tetragonal patterns have been observed experimentally. Our results, combined with the optical trapping of dielectric particles, might provide a promising approach to the realization of a new kind of material-a photonic crystal.

[The results of operative treatment of diastematomyelia]

From May 1978 to July 1993, 31 cases of diastematomyelia were treated surgically. There were 7 males and 24 females, 2 to 34 years old. The follow-up period varied from 2 month to 14.4 years. All patients were couplicated by congenital spinal deformity. Three of them had two septums. The results of operative treatment of the 31 cases were: recovery in 10 cases, remarkable effectiveness in 5, effectiveness in 11, noneffectiveness in 5. The effective rate was 84%. The operative indications and key points were also discussed.

Aging in rats is associated with an increase in adrenal apolipoprotein E

Extrahepatic tissues including the adrenal cortex are capable of synthesizing apolipoprotein E (apoE). Locally synthesized apoE is believed to affect cellular uptake, transport and redistribution of cholesterol within that organ. We and another laboratory have previously reported that the adrenal cortex of aged rats has an elevated cholesteryl ester content. The aim of this work was to investigate whether this elevation is accompanied by increased adrenal apoE levels in aged rats. A Western blotting technique with polyclonal goat anti-human-apoE antiserum was employed as a probe for studies. The results showed that: (a) anti-human-apoE antiserum not only detected apoE in human plasma and adrenal homogenate, but also cross-reacted with a protein (or proteins) resembling apoE in rat plasma and adrenal homogenate (or supernatant) with a molecular weight of 34,000-36,000; (b) rat adrenal apoE concentration (per unit weight of protein) increased with age; (c) the increase did not result from blood trapped in the gland, because after organ perfusion the adrenal of aged rats persistently exhibited 58% more apoE than that of young animals. In conclusion, rat adrenal apoE concentration appears to increase with age. Whether this increase mechanistically causes the accumulation of cholesteryl esters in the aged rat adrenal remains to be investigated.

[Herpes zoster keratoendotheliitis]

Herpes zoster keratoendotheliitis is related to autoimmunity or herpes zoster virus infection. It is characterised by K.P. and interstitial edema. The disease responds well to the administration of steroids and a good result is often achieved.

[A new diarrhea pathogen: entero-SLTs-producing and invasive Escherichia coli was over-looked as normal flora E. coli]

In clinical laboratories of Beijing, China, no known entero-pathogen but almost pure E. coli strains could be isolated from more than 60% fecal samples of diarrheal patients, which had been recognized as normal flora E. coli and dismissed. We suspected that some of the so-called normal flora E. coli strains might be virulent. To prove our idea. We collected 172 strains of E. coli isolated from diarrheal patients from whom no other enteric bacterial pathogens had been identified, including EPEC, EIEC, ETEC. With plasmid DNA analysis, Hep-2 cell adherence assay and 10 DNA probe hybridization, we found that the so-called normal flora E. coli was abnormal, 44% of them were virulent, of which 16 (9.3) were EHEC, 8 EPEC (4.7%), 11 EAggEC (6.8%). Fifty-four of 172 strains were hybridized with INV and SLT1 or SLT2 probes, which had never been reported. These strains could invade Hep-2 cells, but were lack of ipaB gene, a key gene of invasiveness gene cluster of Shigella species and EIEC. The aggregative adherence to Hep-2 cells was observed, but the strains were not hybridized with EAggEC specific DNA probe. The purified toxin protein and cell filtrate were toxic to vero cells. Based on the data obtained, we believed that this is a new category of diarrhea-genic E. coli, named as entero-SLTs-producing and invasive E.coli (ESIEC). ESIEC occupied 31.4% of the strains tested, the isolation of it was probably higher than those of ETEC, EPEC in P R China.

Neurotrophin-4/5 protects hippocampal and cortical neurons against energy deprivation- and excitatory amino acid-induced injury

Neurotrophin-4/5 (NT-4/5) is a recently discovered member of the neurotrophin family of neurotrophic factors which includes NGF, BDNF and NT-3. NT-4/5 is expressed in the brain where its function is unknown. We have found that NT-4/5 can protect cultured embryonic rat hippocampal and cortical neurons against glucose deprivation-induced injury. Significant protection was observed with NT-4/5 concentrations from 100-1000 ng/ml, with a dose-response curve similar to that of BDNF. Neuronal vulnerability to glutamate toxicity was significantly reduced in cultures pretreated with NT-4/5. Moreover, neurons pretreated with NT-4/5 were more resistant to toxicity induced by calcium ionophore A23187, demonstrating that NT-4/5 increases neuronal resistance to calcium-mediated injury. These data indicate that, as with other neurotrophins, NT-4/5 may serve a neuroprotective function in the brain.

Analysis of adrenal cholesteryl esters by reversed phase high performance liquid chromatography

A reversed phase high performance liquid chromatographic (HPLC) method was developed for direct profiling and determination of adrenal cholesteryl ester composition. Cholesteryl adrenate and cholesteryl cervonate, which are not commercially available, were synthesized as markers. Lipid extracts of rat adrenal homogenates or lipid droplets were individually applied to a conditioned silica gel-60 column which separated cholesteryl esters from other native lipids. The eluted cholesteryl ester fraction was then analyzed by HPLC. With cholesteryl heptadecanoate as internal standard, seven adrenal cholesteryl esters were detected and quantified: cholesteryl cervonate, cholesteryl arachidonate, cholesteryl adrenate, cholesteryl myristate, cholesteryl oleate, cholesteryl palmitate, and cholesteryl stearate. Among them, cholesteryl adrenate appeared to be the major sterol ester stored in the rat adrenal.

[Comprehensive evaluation of inheritance and environmental factors in the etiology of primary liver cancer]

A1:1 matched case-control study was carried out in 152 cases with primary liver cancer (PLC) and 152 controls to identify the risk factors associated with it and its cumulative mortality in their second- and third-degree relatives. Results showed cumulative mortality of PLC in the relatives of the cases (0.46%) was significantly higher than that of controls (0.07%). Cumulative mortality of PLC in consanguineous relatives of the cases (0.55%) was significantly higher than that in non-consanguineous ones (0.08%). Cumulative mortality of PLC decreased regularly with family relation (consanguinity) drifting apart. Genetic factors still played an important role independently in the etiology of PLC with multiple regression and stratification analyses studying genetic and environmental factors as a whole. This laid a theoretical basis to study further the association between genetic factors and PLC incidence.

Staurosporine, K-252a, and K-252b stabilize calcium homeostasis and promote survival of CNS neurons in the absence of glucose

Staurosporine, K-252a, and the 9-carboxylic related compound K-252b are low-molecular-weight alkaloids from microbial origin that at high concentrations are kinase inhibitors and can antagonize the effects of neuronal growth factors. Paradoxically, we have found that very low concentrations of these agents (10 fM-10 nM) prolong the survival of hippocampal, septal, and cortical neurons deprived of glucose. These agents did not prevent the depletion of ATP caused by glucose deprivation. The large elevation of intracellular calcium levels that normally mediates glucose deprivation-induced damage was attenuated by staurosporine, K-252a, and K-252b. Western blot analysis using antiphosphotyrosine antibody showed that staurosporine and the K-252 compounds (10-100 pM) stimulated tyrosine phosphorylation of several different proteins. The tyrosine kinase inhibitor genistein significantly reduced the protective effect of staurosporine and the K-252 compounds, indicating that tyrosine phosphorylation was required for neuroprotection by these compounds. Taken together, the data demonstrate that low concentrations of staurosporine and the K-252 compounds can stabilize calcium homeostasis, possibly by a mechanism involving activation of receptor tyrosine kinase transduction pathways.

NT-3 and BDNF protect CNS neurons against metabolic/excitotoxic insults

Neurotrophin-3 (NT-3) and brain-derived neurotrophic factor (BDNF) were recently shown to have biological activity in central neurons. In the present study, NT-3 and BDNF attenuated glucose deprivation-induced neuronal damage dose-dependently in rat hippocampal, septal and cortical cultures. Direct measurements of intraneuronal free calcium levels ([Ca2+]i) and manipulations of calcium influx demonstrated that NT-3 and BDNF each prevented the elevation of [Ca2+]i that mediated glucose deprivation-induced injury. Studies in cultures depleted of glia indicated a direct action of NT-3 and BDNF on neurons. Neurons pretreated with NT-3 or BDNF for 24 hr were more resistant to glutamate neurotoxicity, and showed attenuated [Ca2+]i responses to glutamate. TrkB (BDNF receptor) and trkC (NT-3 receptor) proteins were present in hippocampal, cortical and septal cultures where they were localized to neuronal cell bodies and neurites. The data demonstrate that NT-3 and BDNF can protect neurons against metabolic and excitotoxic insults, and suggest that these neurotrophins may serve [Ca2+]i-stabilizing and neuroprotective functions in the brain.

Tumor necrosis factors protect neurons against metabolic-excitotoxic insults and promote maintenance of calcium homeostasis

Emerging data indicate that neurotrophic factors and cytokines utilize similar signal transduction mechanisms. Although neurotrophic factors can protect CNS neurons against a variety of insults, the role of cytokines in the injury response is unclear. We now report that TNF beta and TNF alpha (1-100 ng/ml) can protect cultured embryonic rat hippocampal, septal, and cortical neurons against glucose deprivation-induced injury and excitatory amino acid toxicity. The elevation of intracellular calcium concentration ([Ca2+]i) induced by glucose deprivation, glutamate, NMDA, or AMPA was attenuated in neurons pretreated with TNF beta. The mechanism whereby TNFs stabilize [Ca2+]i may involve regulation of the expression of proteins involved in maintaining [Ca2+]i homeostasis, since both TNF beta and TNF alpha caused a 4- to 8-fold increase in the number of neurons expressing the calcium-binding protein calbindin-D28k. These data suggest a neuroprotective role for TNFs in the brain's response to injury.

Growth factors protect neurons against excitotoxic/ischemic damage by stabilizing calcium homeostasis

An aberrant elevation in intraneuronal calcium levels resulting from energy failure and excitatory amino acid receptor activation is believed to play a major role in the neuronal damage and death that occur in stroke. We have found that several growth factors can protect cultured rat hippocampal and septal neurons and human cortical neurons from excitotoxic damage caused by glucose deprivation or hypoxia. Using the calcium indicator dye fura 2 and whole-cell patch-clamp recording, we found that glucose deprivation initially results in calcium current inhibition and a reduction in intraneuronal free calcium levels without morphological signs of cell damage. After 12 to 16 hours of glucose deprivation, a large elevation in intraneuronal calcium levels occurred that involved N-methyl-D-aspartate receptor activation and mediated the cell damage and death. Basic fibroblast growth factor (bFGF), nerve growth factor (NGF), and insulin-like growth factors (IGF-I and IGF-II) each prevented, in a dose-dependent manner, glucose deprivation-induced loss of calcium homeostasis and neuronal damage. The growth factors were effective to varying degrees when added up to 12 hours after the onset of glucose deprivation. NGF, bFGF, and IGFs also protected neurons against damage caused by exposure to a hypoxic environment. By stabilizing intraneuronal calcium levels within a window of concentrations conducive to neuronal survival, growth factors can protect neurons against the damaging effects of ischemia-like insults. Because ATP levels are expected to be reduced under ischemia-like conditions, we determined whether the growth factors would protect neurons against a more selective reduction in ATP levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Basic FGF regulates the expression of a functional 71 kDa NMDA receptor protein that mediates calcium influx and neurotoxicity in hippocampal neurons

Basic fibroblast growth factor (bFGF) was recently found to modulate the outgrowth-regulating effects of glutamate, and protected neurons from several brain regions against excitotoxi/ischemic damage. We provide evidence that the excitoprotective mechanism of bFGF involves suppression of the expression of a 71 kDa NMDA receptor protein (NMDARP-71). NMDARP-71 protein and mRNA levels were reduced in neurons in bFGF-treated hippocampal cell cultures. The levels of the NMDARP-71 were not reduced by NGF or epidermal growth factor, and bFGF did not reduce the level of mRNA for the GluR1 kainate/AMPA receptor, demonstrating the specificity of the effect of bFGF on the NMDARP-71. The reduction in NMDARP-71 expression in bFGF-treated neurons was correlated with reduced vulnerability to NMDA neurotoxicity. A major role for NMDARP-71 in calcium responses to NMDA and excitotoxicity was demonstrated using antisense oligonucleotides directed against NMDARP-71. Northern and Western blot analysis and immunocytochemistry showed that NMDARP-71 antisense oligonucleotides caused a selective suppression of NMDARP-71 mRNA and protein levels during 12-44 hr exposure periods. Elevations in intracellular calcium levels normally caused by glutamate and NMDA were attenuated in neurons exposed to NMDARP-71 antisense oligonucleotide; calcium responses to kainate were relatively unaffected. NMDARP-71 antisense oligonucleotides protected the neurons against excitotoxicity. Thus, NMDARP-71 is a necessary component of an NMDA receptor mediating calcium responses and neurotoxicity in hippocampal neurons. Taken together, these data identify a mechanism whereby bFGF can modify neuronal responses to glutamate, and suggest that regulating the expression of excitatory amino acid receptors may provide a means for growth factors to influence the plasticity and degeneration of neural circuits.

beta-Amyloid precursor protein metabolites and loss of neuronal Ca2+ homeostasis in Alzheimer's disease

Recent findings link altered processing of beta-amyloid precursor protein (beta APP) to disruption of neuronal Ca2+ homeostasis and an excitotoxic mechanism of cell death in Alzheimer's disease. A major pathway of beta APP metabolism results in the release of secreted forms of beta APP, APPss. These secreted forms are released in response to electrical activity and can modulate neuronal responses to glutamate, suggesting roles in developmental and synaptic plasticity. beta APP is upregulated in response to neural injury and APPss can protect neurons against excitotoxic or ischemic insults by stabilizing the intracellular Ca2+ concentration [Ca2+]i. An alternative beta APP processing pathway liberates intact beta-amyloid peptide, which can form aggregates that disrupt Ca2+ homeostasis and render neurons vulnerable to metabolic or excitotoxic insults. Genetic abnormalities (e.g. certain beta APP mutations or Down syndrome) and age-related changes in brain metabolism (e.g. reduced energy availability or increased oxidative stress) may favor accumulation of [Ca2+]i-destabilizing beta-amyloid peptide and diminish the release of [Ca2+]i-stabilizing, neuroprotective APPss.

[Separation and purification of human apolipoproteins A-I and C-III by chromatofocusing]

Human very low density lipoprotein (VLDL) and high density lipoprotein (HDL) were isolated and purified by a process of combined dextran sulfate precipitation and density gradient ultracentrifugation. Chromatofocusing, which separates protein based on differences in isoelectric point, was used to separate apolipoprotein A-I (apoA-I) and apolipoprotein C-III from human HDL and VLDL, respectively. Discontinuous SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and analytical isoelectric focusing (IEF) were used to study the purity of different fractions. Both purified apoA-I and apoC-III showed single bands on SDS-PAGE at molecular weights of 28183 and 9400 Daltons, respectively. As determined by IEF in the presence of 8 mol/L urea, apoA-I had eight isoforms with pI of 5.66-5.87. The pI's of the three isoproteins of apoC-III (C-III0, C-III1 and C-III2) were 5.06, 4.88 and 4.72, respectively. Chromatofocusing, a new simple technique combining the high resolving power of IEF with the high capacity of ion-exchange column chromatography, is extremely valuable for large-scale purification of the major apolipoproteins of VLDL and HDL.

[Intraoperative explosive choroidal hemorrhage (report of four cases)]

Intraoperative explosive choroidal hemorrhage (ECH) is a rare, but severe complication of intraocular surgery. This complication often occurs during or after intraocular surgery. We report four cases that developed this complication during surgery. Once the complication occurs, we should use the dehydration medicine intravenously, suture the incision, application of pressure directly to the eye and incise the postsclera. If the bleeding can't be stopped, enucleation is the indication.

Modulation of calcium current, intracellular calcium levels and cell survival by glucose deprivation and growth factors in hippocampal neurons

Basic fibroblast growth factor (bFGF) and nerve growth factor (NGF) can protect CNS neurons against ischemic/excitotoxic insults, but the mechanism of action is unknown. Imaging of the calcium indicator dye fura-2 and whole-cell patch clamp recordings of calcium currents were used to examine the mechanisms whereby hypoglycemia damages and growth factors protect cultured rat hippocampal neurons. When cultures were deprived of glucose, massive neuronal death occurred 16-24 h following the onset of hypoglycemia. Early hypoglycemia-induced changes included calcium current inhibition and a reduction in intracellular free calcium levels ([Ca2+]i) without morphological signs of neuronal damage. Later changes included a large elevation of [Ca2+]i which was causally involved in neuronal damage. NGF and bFGF prevented or reduced both the early and later responses to hypoglycemia. The growth factors increased calcium (barium) current and [Ca2+]i to normal limits during the early stages of hypoglycemia and prevented the later elevation in [Ca2+]i and neuronal damage. Nifedipine, but not omega-conotoxin, blocked calcium currents. The increased calcium current caused by the growth factors was apparently not sufficient to protect neurons against hypoglycemic damage since K+ depolarization during the early stages of hypoglycemia did not prevent and, in fact exacerbated, the subsequent neuronal damage. In addition, exposure of neurons to K+, NGF or bFGF only during the first 1 h of hypoglycemia did not protect against hypoglycemic damage. Taken together, the data suggest that neurons initially respond to hypoglycemia with a reduction in calcium currents which may provide a means to maintain [Ca2+]i within a concentration range conducive to cell survival. Prolonged energy deprivation eventually results in a failure of calcium extrusion systems, glutamate receptor activation and a loss of neuronal calcium homeostasis. Taken together, the data indicate that the mechanism of growth factor protection against energy deprivation involves prevention of the late rise in [Ca2+]i.

Evidence for excitoprotective and intraneuronal calcium-regulating roles for secreted forms of the beta-amyloid precursor protein

The beta-amyloid precursor protein (beta APP) is a membrane-spanning glycoprotein that is the source of the beta-amyloid peptide (beta AP) which accumulates as senile plaques in the brains of patients with Alzheimer's disease. beta APP is normally processed such that a cleavage occurs within the beta AP, liberating secreted forms of beta APP (APPss) from the cell. The neuronal functions of these forms are unknown. We now report that APPss have a potent neuroprotective action in cultured rat hippocampal and septal neurons and in human cortical neurons. APPs695 and APPs751 protected neurons against hypoglycemic damage, and the neuroprotection was abolished by antibodies to a specific region common to both APPs695 and APPs751. APPss caused a rapid and prolonged reduction in [Ca2+]i and prevented the rise in [Ca2+]i that normally mediated hypoglycemic damage. APPss also protected neurons against glutamate neurotoxicity, effectively raising the excitotoxic threshold. APPss may normally play excitoprotective and neuromodulatory roles. Alternative processing of APPss in Alzheimer's disease may contribute to neuronal degeneration by compromising the normal function of APPss and by promoting the deposition of beta AP.

Lacrimal secretion stimulants: sigma receptors and drug implications

3H-DTG (1.3-di(2-[5-3H]tolyl)guanidine) or 3H-haloperidol was added to sigma-receptors (25 nM) in the presence of 25 nM spiperone and incubated with increasing concentrations of bromhexine derivatives (phenylalkylamines; 10(-9) to 10(-2)M) in membrane homogenate suspensions. IC50 values for two derivatives ranged from 3.2 to 8.8 nM for both radioligands. A preferred derivative, 7A (N,N'-dimethyl-2-phenyl-ethylamine), yielded an IC50 of 7.8 nM for 3H-haloperidol but showed much less affinity in displacing 3H-DTG (IC50 = 900 nM). Applying the technic of Bromberg [Exp. Eye Res., 40:313-320, 1985], in vitro protein secretion rates were measured following stimulation of either lacrimal gland slices or isolated, intact lacrimocytes with the compounds. In vitro protein secretion rates exhibit a dose-response relationship with increases in protein release up to a concentration of 10(-8) to 10(-4) M for various derivatives of bromhexine and 10(-4) M for carbachol. By means of Schirmer strips, tear fluid was collected over a five minute period at 10 and 60 minutes post-dosing following the topical application (50 microliters) to the right eye of New Zealand white rabbits (n = 20-24) of 7A at various concentrations. Incubation of lacrimocytes with 7A alone (10(-4) M), with haloperidol (10(-4) M) alone or in combination show that 7A is acting as an agonist to stimulate protein release, whereas haloperidol is acting as an antagonist to inhibit release. In vivo protein secretion rates also show a dose-response curve (at both 10 and 60 minutes post-dosing) for 7A that reach a statistically significant maximum in the dosed eye at a concentration of 0.15% w/v. Analysis of protein extracts using size exclusion HPLC shows an increase in secretory proteins, particularly tear-specific prealbumin.

A new approach for the determination of ventilatory and lactate thresholds

In order to determine the ventilatory threshold (VT) and the lactate threshold (LT) in a reliable way, a new method is proposed and compared with conventional methods. The new method consists of calculating the point that yields the maximal distance from a curve representing ventilatory and metabolic variables as a function of oxygen uptake (VO2) to the line formed by the two end points of the curve (Dmax method). Male cyclists (n = 8) performed two incremental exercise tests a week apart. Ventilatory/metabolic variables were measured and blood was sampled for later lactate measurement during each workload and immediately after exercise. No statistical differences were observed in the threshold values (expressed as absolute oxygen uptake; VO2) determined by the Dmax method and the conventional linear regression method (according to O2 equivalent; EqO2) and venous blood at the onset of blood lactate (OBLA), while VT assessed with the conventional linear method (according to the slope of CO2 output; Vslope) yielded significantly lower threshold values. Similar results were obtained from the reproducibility test. Thus, the Dmax method appears to be an objective and reliable method for threshold determination, which can be applied to various ventilatory or metabolic variables yet yield similar results. The results also showed that breathing frequency can be used to determine VT.

pH regulation in adult rat carotid body glomus cells. Importance of extracellular pH, sodium, and potassium

The course of intracellular pH (pHi) was followed in superfused (36 degrees C) single glomus (type I) cells of the freshly dissociated adult rat carotid body. The cells had been loaded with the pH-sensitive fluorescent dye 2',7'-(2-carboxyethyl)-5 (and -6)-carboxyfluorescein. The high K(+)-nigericin method was used for calibration. The pHi of the glomus cell at pHo 7.40, without CO2, was 7.23 +/- 0.02 (n = 70); in 5% CO2/25 mM HCO3-, pHi was 7.18 +/- 0.08 (n = 9). The pHi was very sensitive to changes in pHo. Without CO2, delta pHi/delta pHo was 0.85 (pHo 6.20-8.00; 32 cells), while in CO2/HCO3- this ratio was 0.82 irrespective of whether pHo (6.80-7.40; 14 cells) was changed at constant PCO2 or at constant [HCO3-]o. The great pHi sensitivity of the glomus cell to pHo is matched only by that of the human red cell. An active Na+/H+ exchanger (apparent Km = 58 +/- 6 mM) is present in glomus cells: Na+ removal or addition of the amiloride derivative 5-(N,N-hexamethylene)-amiloride induced pHi to fall by as much as 0.9. The membrane of these cells also contains a K+/H+ exchanger. Raising [K+]o from 4.7 to 25, 50, or 140 mM reversibly raised pHi by 0.2, 0.3, and 0.6, respectively. Rb+ had no effect, but in corresponding concentrations of Tl+ alkalinization was much faster than in K+. Reducing [K+]o to 1.5 mM lowered pHi by 0.1. These pHi changes were shown not to be due to changes in membrane voltage, and were even more striking in the absence of Na+. Intrinsic buffering power (amount of strong base required to produce, in the nominal absence of CO2, a small pHi rise) increased from 3 to approximately 21 mM as pHi was lowered, but remained nearly unchanged below pHi 6.60. The fitted expression assumed the presence of one "equivalent" intracellular buffer (pK 6.41, 41 mM). The exceptional pHi sensitivity to pHo suggests that the pHi of the glomus cell is a link in the chemoreceptor's response to external acidity.