[A real-time analysis of 133 normal lens images by a computer]

According to the theory that the light scattering of the lens is correlated with the lens density, we designed a computerized system for the real-time analysis of the lens image. By measurement of the gray scale value of the lens optical section, the lens density is measured objectively and numerically. With the help of the system, 133 normal lens images were investigated. From the analysis of various age groups, we found that the grey scale values of the anterior cortex, posterior cortex and nucleus increase with the increase of age (P < 0.01), the grey scale values of the anterior and posterior cortex are significantly higher than the value of the nucleus (P < 0.05), but there is no significant difference between the values of the anterior and posterior cortex (P > 0.05), and there is also no significant difference in the comparisons of the grey scale values of the respective corresponding lens areas between the male and female.

The Saccharomyces cerevisiae Leu3 protein activates expression of GDH1, a key gene in nitrogen assimilation

The Leu3 protein of Saccharomyces cerevisiae has been shown to be a transcriptional regulator of genes encoding enzymes of the branched-chain amino acid biosynthetic pathways. Leu3 binds to upstream activating sequences (UASLEU) found in the promoters of LEU1, LEU2, LEU4, ILV2, and ILV5. In vivo and in vitro studies have shown that activation by Leu3 requires the presence of alpha-isopropylmalate. In at least one case (LEU2), Leu3 actually represses basal-level transcription when alpha-isopropylmalate is absent. Following identification of a UASLEU-homologous sequence in the promoter of GDH1, the gene encoding NADP(+)-dependent glutamate dehydrogenase, we demonstrate that Leu3 specifically interacts with this UASLEU element. We then show that Leu3 is required for full activation of the GDH1 gene. First, the expression of a GDH1-lacZ fusion gene is three- to sixfold lower in a strain lacking the LEU3 gene than in an isogenic LEU3+ strain. Expression is restored to near-normal levels when the leu3 deletion cells are transformed with a LEU3-bearing plasmid. Second, a significant decrease in GDH1-lacZ expression is also seen when the UASLEU of the GDH1-lacZ construct is made nonfunctional by mutation. Third, the steady-state level of GDH1 mRNA decreases about threefold in leu3 null cells. The decrease in GDH1 expression in leu3 null cells is reflected in a diminished specific activity of NADP(+)-dependent glutamate dehydrogenase. We also demonstrate that the level of GDH1-lacZ expression correlates with the cells' ability to generate alpha-isopropylmalate and is lowest in cells unable to produce alpha-isopropylmalate. We conclude that GDH1, which plays an important role in the assimilation of ammonia in yeast cells, is, in part, activated by a Leu3-alpha-isopropylmalate complex. This conclusion suggests that Leu3 participates in transcriptional regulation beyond the branched-chain amino acid biosynthetic pathways.

Surface staining and cytotoxic activity of heat-shock protein 60 antibody in stressed aortic endothelial cells

Heat-shock protein (hsp) expression can be induced by high temperature, exposure to cytokines or oxygen radicals, ischemia, hemodynamic overload, or viral infections. To determine whether surface expression of hsp60 occurs in aortic endothelial cells stressed by high temperature or cytokines, cells from rat aortas were cultivated and stained with several types of monoclonal antibodies against hsp60. Other antibodies, eg, those against intercellular adhesion molecule-1 (ICAM-1), or immune response-associated antigens were also used as controls. Positive staining of endothelial cells on the surface and in the cytoplasm was observed after pretreatment of the cells with cytokine-containing medium, tumor necrosis factor-alpha (TNF-alpha), or interleukin-1 alpha and labeling with a specific monoclonal antibody against hsp60 (II-13). Fluorescence-activated cell sorter analyses showed that over 80% of living endothelial cells stressed by cytokine-containing medium, by TNF-alpha, or at 42 degrees C, but not by interleukin-1 alpha, were positively surface stained with this antibody. Increased intensity of immunostaining with antibodies to ICAM-1 and immune response-associated antigen was also seen on the cytokine-stressed endothelial cells. Furthermore, when TNF-alpha stimulated endothelial cells labeled with 51Cr were incubated with antibody II-13 in the presence of complement, significant lysis occurred. In summary, endothelial cells stressed by high temperature or certain cytokines, eg, TNF-alpha, express hsp60 in the cytoplasm and on their surfaces, and these cells were susceptible to complement-dependent lysis by hsp60-specific antibody. These observations may be significant for elucidating the mechanisms of the involvement of immune reactions to hsp65/60 in initiating atherosclerosis.

Blockade of ornithine decarboxylase enzyme protects against ischemic brain damage

Polyamines are derived from ornithine by the actions of ornithine decarboxylase (ODC), which is the rate-limiting step in this pathway. Polyamines play a role in cell growth, neoplasia, differentiation, and response to injury. We have shown that transient cerebral ischemia gives rise to increased ODC mRNA and enzyme activity in the gerbil brain. ODC and polyamines are thought to be important in the generation of edema and the neuronal cell loss associated with cerebral ischemia. To test this theory, we examined the ODC activity, putrescine levels, and neuronal density in the CA1 region of the hippocampus following ischemia and reperfusion injury in the absence and presence of an inhibitor of ODC activity, alpha-difluoromethylornithine (DFMO). Pretreatment of animals with DFMO resulted in attenuation of the ODC activity following 5 min of ischemia and 4 h of reperfusion. In addition, DFMO prevented the increase in polyamine levels, as determined by measurement of putrescine in the ischemic brain. These alterations were not due to changes in ODC mRNA level. Further analysis revealed that DFMO treatment blocked the delayed neuronal cell death in the CA1 region of the hippocampus that accompanies ischemia and reperfusion injury. Administration of DFMO resulted in a dose-dependent beneficial effect upon neuronal cell survival. These results suggest that ODC enzyme activity and the production of polyamines play a significant role in the response of the brain to ischemic injury.

Activation of recombinant trp by thapsigargin in Sf9 insect cells

The mammalian protein responsible for Ca2+ release-activated current (Icrac) may be homologous to the Drosophila protein designated trp. Thus the activity of trp, and another Drosophila protein designated trp-like or trpl, may be linked to depletion of the internal Ca2+ store via the so-called capacitative Ca2+ entry mechanism. To test this hypothesis, the effect of thapsigargin, a selective inhibitor of the endoplasmic reticulum Ca2+ pump, on trp- and trpl-induced whole cell membrane current was determined using the baculovirus Sf9 insect cell expression system. The results demonstrate that trp and trpl form Ca(2+)-permeable cation channels. The trpl encodes a nonselective cation channel that is constitutively active under basal nonstimulated conditions and is unaffected by thapsigargin, whereas trp is more selective for Ca2+ than Na+ and is activated by depletion of the internal Ca2+ store. Although evaluation of cation selectivity suggests that trp is not identical to the channel responsible for Icrac, these channels must share some structural feature(s) since both are activated by thapsigargin. A unique proline-rich region in the COOH-terminal tail of trp, which is absent in trpl, may be necessary for capacitative Ca2+ entry.

Direct measurement of glutamate release in the brain using a dual enzyme-based electrochemical sensor

The in vivo measurement of the rapid changes in the extracellular concentrations of L-glutamic acid in the mammalian brain during normal neuronal activity or following excessive release due to episodes of anoxia or ischemia has not been possible to this date. Current techniques for the measurement of the release of endogenous glutamate into the extracellular space of the central nervous system are relatively slow and do not measure the actual concentration of free glutamate in the extracellular space. An enzyme-based electrode with rapid response times (about 1 s) and high degree of sensitivity (less than 2 microM) and selectivity for L-glutamic acid is described in this paper. This electrode has both L-glutamate and ascorbate oxidase immobilized on its surface. The latter enzyme removes almost completely any interferences produced by the high levels of extracellular ascorbate present in brain tissue. The response of the electrode to glutamate and other potentially interfering substances was fully characterized in vitro and its selectivity, sensitivity and rapidity in responding to a rise in extracellular glutamate concentrations was also demonstrated in vivo. Placement of the electrode in the dentate gyrus of the hippocampus led to the detection of both KCl-induced release of L-glutamic acid and the release induced by stimulation of the axons in the perforant pathway. The development of this selective, sensitive and rapidly responding glutamate sensor should make it now possible to measure the dynamic events associated with glutamate neurotransmission in the central nervous system.

Isolation of cDNAs encoding guanine nucleotide-binding protein beta-subunit homologues from maize (ZGB1) and Arabidopsis (AGB1)

We have isolated cDNAs from maize (ZGB1) and Arabidopsis (AGB1) encoding proteins homologous to beta subunits of guanine nucleotide-binding protein (G protein). The predicted ZGB1 and AGB1 gene products are 76% identical to each other and 41% or more identical to animal G protein beta subunits. Both predicted proteins contain seven repeats of the so-called "WD-40" motif, where WD is Trp-Asp. RNA blot analysis indicates that ZGB1 mRNA is present in the root, leaf, and tassel and that AGB1 mRNA is expressed in the root, leaf, and flower. DNA blot hybridizations indicate that maize and Arabidopsis genomes contain no other genes that are highly similar to ZGB1 and AGB1, respectively, suggesting that the newly isolated G protein beta-subunit homologues are likely to have unique functions. Furthermore, these G protein beta-subunit homologues are conserved among other plant species and may play important role(s) in plant signaling.

A densovirus newly isolated from the smoky-brown cockroach Periplaneta fuliginosa

We purified a causing agent of fetal disease for smoky-brown cockroach Periplaneta fuliginosa, which was designated as "cockroach small spherical virus (CSSV)". Purified virus particles had a diameter of 22 +/- 0.6 nm and contained DNA as a single-stranded form. However, the extraction of DNA under condition of appropriate high salt and elevated temperature yielded a double-stranded DNA with a size of 5,500 nucleotides. These results were quite similar to those of other densoviruses (DNVs). The CSSV had five structural proteins (VP1: 52 KDa, VP2: 56 KDa, VP3: 79 KDa, VP4: 82 KDa, and VP5: 105 KDa). The SDS-PAGE profile of these proteins was quite different from that of the cockroach DNV previously reported and was rather similar to that of Bombyx mori (Bm) DNV-1. An immunochemical study, however, demonstrated that there was no immunological relationship between the CSSV and the Bm DNV-1. These data suggest that the CSSV is a new member of DNV.

Secosteroid mechanism-based inactivators and site-directed mutagenesis as probes for steroid hormone recognition by 3 alpha-hydroxysteroid dehydrogenase

Rat liver 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD, EC 1.1.1.50) inactivates circulating androgens, progestins, and glucocorticoids. 3 alpha-HSD is a member of the aldo-keto reductase superfamily, and the X-ray structure of the apoenzyme shows the presence of an (alpha/beta)8 barrel [Hoog, S. S., Pawlowski, J. E., Alzari, P. M., Penning, T. M., & Lewis, M. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 2517-2521]. As yet, a three-dimensional structure of the ternary complex E.NADPH.steroid is unavailable. To identify regions of the enzyme involved in steroid hormone recognition, we have employed mechanism-based inactivators and site-directed mutagenesis. (3 RS)-1,10-Seco-5 alpha-estr-1-yne-3,17 beta-diol (1) and (17 RS)- 17-hydroxy-14,15-secoandrost-4-en-15-yn-3-one (3) are secosteroids which contain latent Michael acceptors (alpha,beta-unsaturated alcohols) at opposite ends of the steroid nucleus (at the C-3 and C-17 positions, respectively). It was found that compounds 1 and 3 inactivated 3 alpha-HSD only in the presence of NAD+. The requirement for cofactor implies that 1 and 3 are oxidized to the corresponding alpha,beta-unsaturated ketones for inactivation to occur. Chemically prepared 17 beta-hydroxy-1,10-seco-5 alpha-estr-1-yn-3-one (2) and 14,15-secoandrost-4-en-15-yne-3,17-dione (4), the presumed products of 1 and 3 oxidation, behaved as stoichiometric inactivators of 3 alpha-HSD. In the presence and absence of NAD+, 2 and 4 inactivated > 50% of the enzyme in 10 s or less.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-1 receptor deficiency in brains from NZB and (NZB/NZW)F1 autoimmune mice

Interleukin-1 receptors (IL-1R) are expressed in the brain and the anterior pituitary of normal mice (C3H/He, Swiss), and appear to be involved in the neuroendocrine control of the immune response. Here we have studied the IL-1R density in the brain and the pituitary from several strains of autoimmune mice (NZB, (NZB/NZW)F1, MRL/MP-lpr), using quantitative autoradiography with recombinant human [125I]IL-1 alpha as a ligand. IL-1R was similar in the brain of C3H/He, Swiss and NZW (controls) and MRL/MP-lpr mice. In NZB mice a profound deficit (10% of control mice) in IL-1R was observed exclusively in the dentate gyrus. In (NZB/NZW)F1 the deficit was about 50%. These observations were independent of sex and age. Pituitary receptors were not affected in all the strains except NZW (30% increase). Competition experiments demonstrated that the affinity of IL-1R was not modified in dentate gyrus of (NZB/NZW)F1 and NZW mice. Thus, the number of IL-1R was the only parameter affected. This deficit was not reversed by corticosterone treatment (0.2 mg/20 g body weight, i.p.) and was poorly modified by lipopolysaccharide treatment (0.1 mg/20 g body weight, i.p.) compared to C3H/He mice. In conclusion, this central IL-1R deficit is unlikely to be the consequence of occupancy by abnormal synthesis of brain IL-1. This abnormality is tissue-specific with hereditary autosomal transmission. The role of central IL-1R in neuroimmunoendocrine interactions and in autoimmunity remains to be clarified.

Expression of Thy-1/lacZ fusion genes in the CNS of transgenic mice

Thy-1 is a cell surface glycoprotein of unknown function that is found on nerve cells and mature T-lymphocytes. To study the regulation of Thy-1 gene expression, mouse Thy-1.2 genomic sequences were joined to various marker sequences and the resulting chimeric constructs were used to produce nearly three dozen independent lines of transgenic mice. The starting point for our studies was an 8.2 kb EcoRI fragment that begins 1.7 kb 5' to the transcription start site and ends with 1.3 kb of 3' flanking sequences. Addition of a small marker oligonucleotide to the 3' untranslated region of this fragment had little or no effect on gene regulation. All of the lines derived from injection of this construct expressed the transgene in the appropriate tissues. Thus, as expected, the Thy-1.2 genomic fragment contains all of the information necessary for tissue-specific, position-independent expression of the modified transgene. Unexpectedly, Thy-1/lacZ hybrid genes did not mimic this behavior. Using either mRNA or histochemical detection of lacZ protein, these constructs were expressed in patterns that varied dramatically from line to line. This behavior suggests that integration site-specific effects dominate the cis-active Thy-1 regulatory elements leading to wide variability of expression. This is further emphasized by the observation that the bacterial reporter protein was found in a few non-neuronal cell-types, in contrast to the known pattern of native Thy-1 expression. These results suggest that either the Thy-1.2 sequences which are necessary for appropriate brain-specific expression are not contained solely within the proposed CNS enhancer in the first intron, or that fusion of the Thy-1.2 sequences with the lacZ coding region may disrupt normal Thy-1 regulatory signals (or result in the creation of new regulatory elements).

Appearance of a novel Ca2+ influx pathway in Sf9 insect cells following expression of the transient receptor potential-like (trpl) protein of Drosophila

Activation of phospholipase C, elevation of free cytosolic Ca2+ concentration ([Ca2+]i) and stimulation of Ca2+ influx have been implicated in Drosophila phototransduction. Electrophysiological studies suggest that trp and trpl proteins may be important for the light-activated Ca2+ current found in Drosophila photoreceptor cells. Although these proteins exhibit homologies to voltage-gated Ca2+ and Na+ channels, their actual function in insect cells and their relation to proteins involved in mammalian cell Ca2+ signaling remains unknown. In the present study, [Ca2+]i was examined in fura-2-loaded Sf9 insect cells infected with recombinant baculovirus containing cDNA for the trpl protein. Ca2+ influx was examined by use of Ba2+, a Ca2+ surrogate that is not a substrate for Ca(2+)-pumps or carriers and by measurement of whole-cell membrane currents. The results suggest that expression of trpl is associated with appearance of a Ca2+ permeable, non-selective cation channel formed by the trpl protein.

Ca2+ signaling in Sf9 insect cells and the functional expression of a rat brain M5 muscarinic receptor

The purpose of the present study was to examine Ca2+ signaling mechanisms in Sf9 cells and to demonstrate expression and functional linkage of a mammalian receptor to changes in cytosolic free Ca2+ concentration ([Ca2+]i). Addition of p-octopamine (50 microM to fura 2-loaded Sf9 cells produced a small transient increase in [Ca2+]i from a basal level of 58 +/- 10 to 194 +/- 7.6 (SD) nM. The response to octopamine was inhibited by both cyproheptadine and chlorpromazine and was mimicked by clonidine. In contrast, [Ca2+]i did not change in response to dopamine (50 microM), substance P (50 nM), histamine (50 microM), ATP (50 microM), acetylcholine (10 or 100 microM), carbachol (10 or 100 microM), serotonin (50 microM), epinephrine (10 microM), or bradykinin (50 nM). The Ca(2+)-adenosinetriphosphatase inhibitors thapsigargin (200 nM) and 2,5-di-tert-butylhydroquinone (BHQ; 10 microM) increased [Ca2+]i to 307 +/- 13 and 137 +/- 20 nM, respectively. In contrast to BHQ, the response to thapsigargin was attenuated by La3+ or removal of extracellular Ca2+ and increased by elevation of extracellular Ca2+. These results suggest that thapsigargin but not BHQ stimulates Ca2+ influx. The rat brain muscarinic receptor (subtype M5) was incorporated into the baculovirus by homologous recombination. Addition of carbachol (100 microM) increased [Ca2+]i from 92.7 +/- 6.4 to 480 +/- 26 nM in Sf9 cells infected with recombinant virus containing the M5 receptor cDNA. The effect of carbachol on [Ca2+]i was concentration dependent with a 50% effective concentration of approximately 30 microM and was blocked by atropine (10 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

Chlormethiazole as an efficient inhibitor of cytochrome P450 2E1 expression in rat liver

Ethanol-inducible cytochrome P450 (CYP) 2E1 (CYP2E1) is responsible for the metabolism of many xenobiotics which exert toxic effects in humans. Specific inhibitors might constitute valuable tools in the elucidation of the pharmacological and toxicological roles of this isozyme in vivo. In the present investigation we have evaluated the effects of a drug used for treatment of ethanol withdrawal states, chloromethiazole (CMZ), on CYP2E1 expression in rat liver. A 4-fold induction of CYP2E1 was observed after 3 days of starvation, accompanied by a similar increase in the level of the corresponding mRNA. CMZ specifically inhibited the elevation of CYP2E1 mRNA and protein, but did not prevent CYP2B1 and CYP3A1 or CYP1A1 induction caused by treatment with phenobarbital or beta-naphthoflavone, respectively. From nuclear run-off experiments it was apparent that the rate of the CYP2E1 gene transcription was inhibited greatly by CMZ treatment. Rats treated with ethanol in a total enteral nutrition model had higher CYP2E1-dependent hepatic microsomal activities of p-nitrophenol hydroxylase and carbon tetrachloride-induced lipid peroxidation than controls, and simultaneous CMZ treatment abolished the ethanol-dependent induction. In vitro experiments with rat liver microsomes showed that CMZ did not act as an inhibitor of CYP2E1-dependent catalytic activities or as an inhibitor of microsomal NADPH and CYP2E1-dependent lipid peroxidation. In conclusion, we suggest that CMZ might constitute an efficient and specific inhibitor of CYP2E1 expression suitable for in vivo experiments.

Reduction of acetaminophen interference in glucose sensors by a composite Nafion membrane: demonstration in rats and man

Amperometric glucose sensors typically monitor the production of hydrogen peroxide generated in the course of the enzymatic oxidation of glucose. At the applied potential necessary to oxidize the peroxide produced, other species are also electroactive and contribute to the signal. Interference of ascorbate or urate has been effectively eliminated, but that resulting from the widely used analgesic acetaminophen is not. The aim of this work was to reduce this interference, which was found to be possible by introducing a membrane constructed of Nafion. We compared the in vitro sensitivity to acetaminophen of five Nafion sensors with that of five non-Nafion sensors with identical glucose sensitivity (2.0 +/- 0.4 vs 1.9 +/- 0.1 nA.mmol-1.l-1, NS): sensitivity to acetaminophen was 12.2 +/- 2.7 vs 30.8 +/- 6.3 nA.mmol-1.l-1, respectively (p < 0.05). These sensors were tested in rats by implanting in each animal one Nafion and one non-Nafion sensors. The in vivo sensitivity to glucose was similar (0.33 +/- 0.09 vs 0.30 +/- 0.05 nA.mmol-1.l-1, NS). The current generated by an acetaminophen infusion (plasma acetaminophen plateau = 140 +/- 10 mumol/l) was much decreased in the case of the Nafion sensor: 0.5 +/- 0.3 vs 2.0 +/- 0.7 nA, p < 0.05). Five Nafion sensors were implanted in the subcutaneous tissue of normal human volunteers who were given on oral dose of 500 mg acetaminophen.(ABSTRACT TRUNCATED AT 250 WORDS)

Synaptobrevin/vesicle-associated membrane protein (VAMP) of Aplysia californica: structure and proteolysis by tetanus toxin and botulinal neurotoxins type D and F

Synaptobrevin/vesicle-associated membrane protein (VAMP) and syntaxin are potential vesicle donor and target membrane receptors of a docking complex that requires N-ethylmaleimide-sensitive factor (NSF) and soluble NSF-attachment proteins as soluble factors for vesicle fusion with target membranes. Members of this docking complex are the target of clostridial neurotoxins that act as zinc-dependent proteases. Molecular cloning of the Aplysia californica synaptobrevin cDNA revealed a 180-residue polypeptide (M(r), 19,745) with a central transmembrane region and an atypically large C-terminal intravesicular domain. This polypeptide integrates into membranes at both the co- and posttranslational level, as shown by modification of an artificially introduced N-glycosylation site. The soluble and membrane-anchored forms of synaptobrevin are cleaved by the light chains of the botulinal toxins type D and F and by tetanus toxin involving the peptide bonds Lys49-Ile50, Gln48-Lys49, and Gln66-Phe67, respectively. The active center of teh tetanus toxin light chain was identified by site-specific mutagenesis. His233, His237, Glu234, and Glu270/271 are essential to this proteolytic activity. Modification of histidine residues resulted in loss of zinc binding, whereas a replacement of Glu234 only slightly reduced the zinc content.

Role of guanylyl cyclase and cGMP-dependent protein kinase in long-term potentiation

Several lines of evidence suggest that cyclic GMP might be involved in long-term potentiation (LTP) in the hippocampus. Arachidonic acid, nitric oxide and carbon monoxide, three molecules that have been proposed to act as retrograde messengers in LTP, all activate soluble guanylyl cyclase. We report here that an inhibitor of guanylyl cyclase blocks the induction of LTP in the CA1 region of hippocampal slices. Conversely, cGMP analogues produce long-lasting enhancement of the excitatory postsynaptic potential if they are applied at the same time as weak tetanic stimulation of the presynaptic fibres. The enhancement is spatially restricted, is not blocked by valeric acid (APV), nifedipine, or picrotoxin, and partially occludes LTP. This synaptic enhancement may be mediated by the cGMP-dependent protein kinase (PKG). Inhibitors of PKG block the induction of LTP, and activators of PKG produce activity-dependent long-lasting enhancement. These results suggest that guanylyl cyclase and PKG contribute to LTP, possibly as activity-dependent presynaptic effectors of retrograde messengers.

[Epidemiologic features and the stepwise regression analysis of fatal motor vehicle accidents in Guangzhou]

This paper describes the epidemiologic features of 1,532 fatal motor vehicle crashes, and analyses of some crash-related factors by means of stepwise regression analysis as well. The crashes between motor vehicle and bicycle accounted for 39.49 percent. The 36.84 percent of drivers responsible for accidents were at the age of 20-24. The analysis of accident victim characteristics indicated that all age groups were at risk. Most victims were the people younger than 25 years old as well as aged 50 and over. About one-third of the victims were peasants. The analysis of stepwise regression suggested that the crashes were positively related to the quantity of automobile and the ratio between male and female.

Elimination of the acetaminophen interference in an implantable glucose sensor

Acetaminophen has been one of the most serious electrochemical interferences to oxidase-based amperometric biosensors that measure H2O2. A study was carried out to investigate various polymer materials for their selectivity as the sensor inner membrane. A composite membrane of cellulose acetate and Nafion was found to eliminate acetaminophen and other electrochemical interferences effectively while at the same time maintaining reasonable diffusivity for hydrogen peroxide. The excellent in vivo performance of the sensor was attributed not only to significantly reduced steady-state sensitivity to acetaminophen but also to very slow acetaminophen response. These features, combined with rapid acetaminophen clearance pharmacokinetics, led to the decreased response as demonstrated in the rat.

Downregulation of beta-adrenergic receptors and signal transduction response in salivary glands of NOD mice

The nonobese diabetic (NOD) mouse is subject to autoimmune disease-associated lymphocytic attack on the salivary glands with a corresponding loss of exocrine function. Downregulation of stimulus response to the beta-adrenoceptor agonist, isoproterenol, appears to be related to a decline in beta-adrenergic receptor density, changes in the level of intracellular second messenger signaling component adenosine 3',5'-cyclic monophosphate, and protein kinase A activity. An autoantibody to the beta 1-adrenergic receptor present in the sera of diabetic NOD mice may be involved in the reduced agonist response by virtue of its ability to retard dihydroalprenolol radioligand binding to receptors in the membranes of salivary glands from control mice and recognition of purified beta 1-adrenergic receptor by immunoblotting techniques.

[Recurrent astrocytoma versus primary astrocytoma: a comparative study of morphological changes of 32 cases]

The pathologic morphological changes of 32 cases of recurrent astrocytoma (RA) and primary astrocytoma were reported. During recurrence, 20 cases (62.5%) of astrocytomas transformed into cases at higher grades. Twelve cases remained at the same grades as primary tumors. Among 21 cases of RA at grades III and IV, 15 cases (71.4%) came from primary astrocytomas, grades I and II. The change from astrocytoma grade I to grade III or IV took time longer than that from grade II to grade III or IV. The recurrent time of astrocytomas with different grades showed no statistical differences. Postoperative radiotherapy/chemotherapy did not play a major role in grading changes and recurrent time.

[Experimental study on the role of oxygen-free radicals in ischemic reperfusion tissue injury is island skin flaps]

In this study the role of oxygen-free radicals and the effect of treatment with superoxide dismutase (SOD) had been investigated in a 3 x 6 cm2 abdominal area island skin flaps of rat model which were subjected to 8 hours of total venous occlusion. In experiment 1, 56 rats were divided into seven test groups. Tissue assay for Malonydialdehyde (MDA) were obtained. Flaps with ischemia had higher MDA at 8.12 hours and all reperfusion groups had higher MDA as compared to the control groups (P < 0.01). In reperfusion groups, the MDA had increased at 4.8 hours compared to ischemia group at the same time. In experimental 2, 28 rats were used. Treatment with superoxide dismutase injected into the artery following the onset of reperfusion significantly enhanced island flap survival from 28.6% (4/14) to 78.6% (11/14) (P < 0.01).