Accumulation of amyloid beta and tau and the formation of neurofilament inclusions following diffuse brain injury in the pig

Brain trauma in humans increases the risk for developing Alzheimer disease (AD) and may induce the acute formation of AD-like plaques containing amyloid beta (A beta). To further explore the potential link between brain trauma and neurodegeneration, we conducted neuropathological studies using a pig model of diffuse brain injury. Brain injury was induced in anesthetized animals via nonimpact head rotational acceleration of 110 degrees over 20 ms in the coronal plane (n = 15 injured, n = 3 noninjured). At 1, 3, 7, and 10 days post-trauma, control and injured animals were euthanized and immunohistochemical analysis was performed on brain sections using antibodies specific for A beta, beta-amyloid precursor protein (betaPP), tau, and neurofilament (NF) proteins. In addition to diffuse axonal pathology, we detected accumulation of A beta and tau that colocalized with immunoreactive betaPP and NF in damaged axons throughout the white matter in all injured animals at 3-10 days post-trauma. In a subset of brain injured animals, diffuse A beta-containing plaque-like profiles were found in both the gray and white matter, and accumulations of tau and NF rich inclusions were observed in neuronal perikarya. These results show that this pig model of diffuse brain injury is characterized by accumulations of proteins that also form pathological aggregates in AD and related neurodegenerative diseases.

Evolution of neurofilament subtype accumulation in axons following diffuse brain injury in the pig

Although accumulation of neurofilament (NF) proteins in axons has been recognized as a prominent feature of brain trauma, the temporal course of the accumulation of specific NF subtypes has not been well established. In the present study, 17 miniature swine were subjected to nonimpact inertial brain injury. At 3 hours (h), 6 h, 24 h, 3 days, 7 days, and 10 days post-trauma, immunohistochemical analysis was performed to determine axonal accumulation of NF-light (NF-L), the rod and sidearm domains and sidearm phosphorylation states of NF-medium (NF-M), and heavy (NF-H). We found that NF-L accumulation was easily identified in damaged axons by 6 h post-trauma, but NF-M and H accumulation was not clearly visualized until 3 days following injury. In addition, the axonal accumulation of NF-M and H appeared to be primarily comprised of the sidearm domains. While the accumulating NF was found to be predominantly dephosphorylated, we also detected accumulation of phosphorylated NF. Finally, we found that developing axonal pathology may proceed either towards axotomy with discrete terminal bulb formation or towards the development of varicose swellings encompassing long portions of axons. These findings suggest that there is a differential temporal course in NF subtype disassembly, dephosphorylation, and accumulation in axons following initial brain trauma and that these processes occur in morphologically distinct phenotypes of maturing axonal pathology.

Genetic evidence for interactions between yeast importin alpha (Srp1p) and its nuclear export receptor, Cse1p

The yeast Srp1p protein functions as an import receptor for proteins bearing basic nuclear localization signals. Cse1p, the yeast homolog of mammalian CAS, recycles Srp1p back to the cytoplasm after import substrates have been released into the nucleoplasm. In this report we describe genetic interactions between SRP1 and CSE1. Results from genetic suppression and synthetic lethality studies demonstrate that these gene products interact to ensure accurate chromosome segregation. We also describe new mutant alleles of CSE1 and analyze a new temperature-sensitive allele of CSE1, cse1-2. This allele causes high levels of chromosome missegregation and cell cycle arrest during mitosis at the nonpermissive temperature.

Diffuse axonal pathology detected with magnetization transfer imaging following brain injury in the pig

This study was designed to evaluate with magnetization transfer imaging (MTI) and conventional magnetic resonance (MR) imaging the manifestation of diffuse axonal injury (DAI) in an animal model of injury via nonimpact coronal plane rotational acceleration. A second objective was to investigate the diagnostic use of quantitative MTR imaging based on statistical parameters in a single subject, as opposed to grouped analysis. Seven mini-swine were subjected to brain trauma known to produce isolated DAI and to MR imaging at two time points. Following sacrifice, the brains were harvested for histopathologic examination. Magnetization transfer ratio (MTR) maps were generated for double-blinded comparison of regions with abnormal MTR values and regions with documented DAI. Positive and negative predictive values for MTR detection of DAI were 67 and 56%, respectively, and in acute studies alone, 89 and 61%. Gains in sensitivity over conventional imaging for detection of DAI were demonstrated.

Brain trauma induces massive hippocampal neuron death linked to a surge in beta-amyloid levels in mice overexpressing mutant amyloid precursor protein

Although brain trauma is a risk factor for Alzheimer's disease, no experimental model has been generated to explore this relationship. We developed a model of brain trauma in transgenic mice that overexpress mutant human amyloid precursor protein (PDAPP) leading to the appearance of Alzheimer's disease-like beta-amyloid (Abeta) plaques beginning at 6 months of age. We induced cortical impact brain injury in the PDAPP animals and their wild-type littermates at 4 months of age, ie, before Abeta plaque formation, and evaluated changes in posttraumatic memory function, histopathology, and regional tissue levels of the Abeta peptides Abeta1-40 and Abeta1-42. We found that noninjured PDAPP mice had impaired memory function compared to noninjured wild-type littermates (P < 0.01) and that brain-injured PDAPP mice had more profound memory dysfunction than brain-injured wild-type littermates (P < 0.001). Although no augmentation of Abeta plaque formation was observed in brain-injured PDAPP mice, a substantial exacerbation of neuron death was found in the hippocampus (P < 0.001) in association with an acute threefold increase in Abeta1-40 and sevenfold increase in Abeta1-42 levels selectively in the hippocampus (P < 0.01). These data suggest a mechanistic link between brain trauma and Abeta levels and the death of neurons.

Magnetic resonance spectroscopy of diffuse brain trauma in the pig

The acute metabolic events linked to the evolution of selective axonal pathology in the white matter following diffuse brain injury have not previously been evaluated due to the paucity of relevant experimental models. Here, we utilized a new model of inertial brain injury in the pig that selectively damages axons in the white matter, and applied proton and phosphorous magnetic resonance spectroscopy (MRS) to noninvasively monitor the temporal course of metabolic changes following trauma. Evaluating four pigs with MRS prior to injury, within 1 h and 3 and 7 days postinjury, we found that widespread axonal injury was produced in the absence of changes in pH, PCr/Pi, or the concentrations of ATP, and lactate. However, we did observe an acute 60% loss of intracellular Mg2+ levels, which gradually resolved by 7 days postinjury. In addition, we found that the levels of the neuron marker, N-acetylaspartate (NAA), acutely dropped 20% and remained persistently decreased for at least 7 days postinjury. Moreover, the changes in Mg2+ and NAA were found with MRS in the absence of abnormalities with conventional magnetic resonance imaging (MRI). These results show that (1) profound alterations in intracellular metabolism occur acutely following diffuse axonal pathology in the white matter, but in the absence of indicators of ischemia, and (2) axonal pathology may be evaluated with high sensitivity utilizing noninvasive MRS techniques.

Effects of nitroquine on ultrastructures and cytochrome oxidase of exoerythrocytic Plasmodium yoelii in rat liver

AIM

To study the effects of nitroquine acetate (NA) on the ultrastructures and cytochrome-c oxidase (CCO) of exoerythrocytic forms (EEF) of Plasmodium yoelii.

METHODS

Rats were inoculated with sporozoites directly into the liver. After 48 h rats were killed. Rat liver thin sections were incubated in histochemical reaction medium, then examined by transmission electron microscopy. NA (2 mg.kg-1) was fed to rats 3.5 h and 14 h before killing the rats.

RESULTS

At 3.5 h, in the parasites there appeared swelling and proliferation of mitochondria, dilation of endoplasmic reticulum, and reduction of the electron density of parasites' nuclei. The structures of the parasites disintegrated to form many autophagocytes 14 h after exposure to NA. The reaction products of CCO still existed until 14 h after using NA.

CONCLUSION

CCO was not the starting point of NA action. NA interferes with the structure and function of the cytoplasm and nucleus of malaria parasites and exerts its antimalarial effects in many aspects.

ErbB2 expression increases the spectrum and potency of ligand-mediated signal transduction through ErbB4

Interleukin 3-dependent murine 32D cells do not detectably express members of the ErbB receptor family and do not proliferate in response to known ligands for these receptors. 32D transfectants were generated expressing human ErbB4 alone (32D.E4) or with ErbB2 (32D.E2/E4). Epidermal growth factor (EGF), neuregulin 1-beta (NRG1-beta), betacellulin (BTC), transforming growth factor-alpha (TGF-alpha), heparin binding-EGF (HB-EGF), and amphiregulin were analyzed for their ability to mediate mitogenesis in these transfectants. 32D.E4 responded mitogenically to NRG1-beta and BTC. Surprisingly, EGF also induced significant DNA synthesis and TGF-alpha was negligibly mitogenic on 32D.E4 cells, whereas HB-EGF and amphiregulin were inactive. Although coexpression of ErbB2 with ErbB4 in 32D.E2/E4 cells did not significantly alter DNA synthesis in response to NRG1-beta or BTC, it greatly enhanced mitogenesis elicited by EGF and TGF-alpha and unmasked the ability of HB-EGF to induce proliferation. EGF-related ligands that exhibited potent mitogenic activity on 32D.E2/E4 cells at low concentrations induced adherence, morphological alterations, and up-regulation of the Mac-1 integrin and FcgammaRII/III at higher concentrations. While 125I-EGF could be specifically crosslinked to both 32D.E4 and 32D.E2/E4 cells, its crosslinking capacity was greatly enhanced in the cotransfected cells. The ability of the various ligands to mediate proliferation and/or adhesion in the two transfectants correlated with their capacity to induce substrate tyrosine phosphorylation and to initiate and sustain activation of mitogen-activated protein kinase. We conclude that the ability of ErbB4 to mediate signal transduction through EGF-like ligands is broader than previously assumed and can be profoundly altered by the concomitant expression of ErbB2.

CCK(B) receptors in the periaqueductal grey are involved in electroacupuncture antinociception in the rat cold water tail-flick test

Cholecystokinin octapeptide (CCK-8) (0.25-2.0 ng), the CCK(A) receptor antagonist L-364,718 (60-100 ng) or the CCK(B) receptor antagonist L-365,260 (0.3125-1.25 ng) was administered into the periaqueductal grey (PAG) of male SD rats. The antinociceptive effect induced by electroacupuncture (EA) stimulation of different frequencies was then measured by the cold water tail-flick (CWT) test. The results showed that (1) microinjection of CCK-8 into the PAG can significantly block the antinociceptive effect induced by all frequencies of EA stimulation. The effectiveness of the blockade was 100 > 2 Hz. In addition, CCK-8 blocks the antinociception seen following termination of the electrical stimulation at 100 Hz; (2) microinjection of L-365,260 (1.25 ng) into the PAG significantly increased the 100 Hz EA antinociceptive effect but not the 2 Hz EA antinociceptive effect and microinjection of L-364,718 into PAG did not affect either 2 or 100 Hz EA antinociception. These results demonstrate that CCK-8 in the PAG can antagonize the antinociceptive effect induced by EA stimulation, and the CCK effect is likely to be mediated by the CCK(B) receptor, but not the CCK(A) receptor.

Aspartate substitutions establish the concerted action of P-region glutamates in repeats I and III in forming the protonation site of L-type Ca2+ channels

Hydrogen ions reduce ion flux through voltage-gated Ca2+ channels by binding to a single protonation site with an unusually high pKa. Recent evidence localizes the protonation site to the same locus that supports high affinity Ca2+ binding and selectivity, a set of four conserved glutamate residues near the external mouth of the pore. Remaining controversy concerns the question of whether the protonation site arises from a single glutamate, Glu-1086 (EIII), or a combination of Glu-1086 and Glu-334 (EI) working in concert. We tested these hypotheses with individual Glu --> Asp substitutions. The Glu --> Asp replacements in repeats I and III stood out in two ways. First, in both EID and EIIID, protonation was destabilized relative to wild type, whereas it was unchanged in EIID and stabilized in EIVD. The changes in affinity were entirely due to alterations in H+ off-rate. Second, the ratio of protonated conductance to deprotonated conductance was significantly closer to unity for EID and EIIID than for wild-type channels or other Asp mutants. Both results support the idea that EI and EIII act together to stabilize a single titratable H+ ion and behave nearly symmetrically in influencing pore conductance. Neutralization of EIII by alanine replacement clearly failed to abolish susceptibility to protonation, indicating that no single glutamate was absolutely required. Taken together, all the evidence supports a model in which multiple carboxylates work in concert to form a single high affinity protonation site.

[Effect of zuogui wan on the contents of hypothalamic monoaminic transmitters and body weight in rats treated with monosodium glutamate neonatally]

OBJECTIVE

To evaluate the interrelationship between the traditional Chinese medicine the Kidney-Yin Deficiency Syndrome and the metabolism of hypothalamic monoaminic neurotransmitters after the lesion of arcuate nucleus (ARC).

METHODS

Rats were injected with monosodium glutamate (MSG, at 2, 4, 6, 8, 10 days after born. 4 mg/g body weight, s.c.) during the neonatal period, then the contents of hypothalamic monoaminic transmitters were determined with HPLC and the changes of increase of body weight were observed.

RESULTS

Decreases in levels of norepinephrine (NE), dopamine (DA) associated with its metabolite, 3,4-dihydroxyphenyl acetic acid (DOPAC) were observed, while vanillylmandelic acid (VMA), metabolite of NE, serotonin (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) were unchanged. Furthermore, adult rats with neonatal MSG treatment also demonstrated growth retardation, obesity but lower body weight, and shorter length of naso-anal. Zuogui Wan, classical drugs of nourishing and recuperating the Kidney-Yin, relieved the disorder of the metabolism of hypothalamic monoaminic transmitter in MSG-rats.

CONCLUSION

The metabolic disorders of the central monoaminic transmitters may be related with the Deficiency of the Kidney-Yin.

Progressive atrophy and neuron death for one year following brain trauma in the rat

Although atrophic changes have been well described following traumatic brain injury (TBI) in humans, little is known concerning the mechanisms or progression of brain tissue loss. In the present study, we evaluated the temporal profile of histopathological changes following parasagittal fluid-percussion (FP) brain injury in rats over 1 year postinjury. Anesthetized 3-4 month-old Sprague-Dawley Rats (n = 51) were subjected to FP brain injury of high severity (2.5-2.9 atm, n = 51) or sham treatment (n = 27). At 1 h, 2 h, 48 h, 1 week, 2 weeks, 1 month, 2 months, 6 months and 1 year after brain injury or sham treatment, these animals were humanely euthanized. Brain sections were analyzed with image-processing techniques to determine the extent of cortical tissue loss and shrinkage of the hippocampal pyramidal cell layer. In addition, cell counting was performed to determine the number of neurons in the dentate hilus of the hippocampus, and glial fibrillary acidic protein (GFAP) immunostaining was used to reveal reactive astrocytosis. Examination of the injured brains revealed substantial and progressive tissue loss with concomitant ventriculomegaly in the hemisphere ipsilateral to injury. The regions with the most notable progressive atrophy included the cortex, hippocampus, thalamus, and septum. Quantitative analysis demonstrated a significantly progressive loss of cortical tissue as well as shrinkage of the hippocampal pyramidal cell layer ipsilateral to injury over 1 year following injury. In addition, reactive astrocytosis in regions of atrophy and progressive bilateral death of neurons in the dentate hilus was observed for 1 year following injury. These results suggest that a chronically progressive degenerative process may be initiated by brain trauma. Thus, there is a temporally broad window within which to introduce novel therapeutic strategies designed to ameliorate the short and long-term consequences of brain trauma.

Characterization of diffuse axonal pathology and selective hippocampal damage following inertial brain trauma in the pig

Dynamic deformation applied to white matter tracts is a common feature of human brain trauma, and may result in diffuse axonal injury (DAI). To produce DAI in an experimental model, we have utilized nonimpact inertial loading to induce brain trauma in miniature swine. This species was chosen due to its large gyrencephalic brain with substantial white matter domains. Twenty anesthetized (2% isoflurane) miniature swine were subjected to pure impulsive centroidal rotation 110 degrees in the coronal plane in 4 to 6 ms; peak accelerations ranged from 0.6 to 1.7 x 10(5) rad/s2. Seven days following injury, the brains were fixed (4% paraformaldehyde). Histopathologic examination was performed on 40 microns sections stained with cresyl violet (Nissl), antibodies targeting neurofilament (axonal damage), GFAP (astrocytes), and pig IgG (protein extravasation). Widespread multifocal axonal injury was observed in combination with gliosis throughout the brain, most commonly in the root of gyri and at the interface of the gray and white matter. Very little vascular disruption was noted in regions of axonal injury. Neuronal damage was primarily found in the CA1 and CA3 subfields of the hippocampus. These results suggest that this model is clinically relevant and useful for evaluating mechanisms of inertial brain trauma.

Jak1 expression is required for mediating interleukin-4-induced tyrosine phosphorylation of insulin receptor substrate and Stat6 signaling molecules

The Jak1, Jak2, Jak3, and Fes tyrosine kinases have been demonstrated to undergo tyrosine phosphorylation in response to interleukin (IL)-4 stimulation in different cell systems. However, it is not clear which, if any, of these kinases are responsible for initiating IL-4-induced tyrosine phosphorylation of intracellular substrates in vivo. In the present study, we have utilized a mutant Jak1-deficient HeLa cell line, E1C3, and its parental Jak1-expressing counterpart, 1D4, to analyze the role of Jak1 in mediating IL-4-induced tyrosine phosphorylation events. IL-4 treatment rapidly induced tyrosine phosphorylation of insulin receptor substrate (IRS)-1 and IRS-2 in 1D4 but not in E1C3 cells. IL-4-mediated tyrosine phosphorylation of Stat6 was pronounced in 1D4 cells, while no IL-4-induced Stat6 phosphorylation was detected in E1C3 cells. IL-4 also induced Stat6 DNA binding activity from lysates of 1D4 but not E1C3 cells utilizing a radiolabeled immunoglobulin heavy chain germline epsilon promotor sequence (Iepsilon) in an electrophoretic mobility shift assay. Reconstitution of Jak1 expression in E1C3 cells restored the ability of IL-4 to induce IRS and Stat6 tyrosine phosphorylation. These results provide evidence that Jak1 expression is required for mediating tyrosine phosphorylation and activation of crucial molecules involved in IL-4 signal transduction.

Antisense confirmation of mu- and kappa-opioid receptor mediation of morphine's effects on body temperature in rats

Previous studies showed that parenterally administered morphine at 4-16 mg/kg markedly increased body temperature in the rat, but higher doses of morphine (> or = 30 mg/kg, subcutaneously, sc) caused a profound decrease in body temperature. Based on the use of selective opioid agonists and antagonists, we postulated that these effects were due to morphine's actions on mu and kappa receptors, respectively. In the present study, we sought to determine whether an antisense (AS) oligodeoxynucleotide (oligo) against cloned mu or kappa opioid receptors could affect morphine-induced body temperature changes. AS oligos were directed against nucleotides 1-18 of the coding region of the mu receptor and 4-21 of the coding region of the kappa receptor. Male SD rats were surgically implanted with intracerebroventricular (icv) cannulae. Rats received icv injections of vehicle or oligo in the animal colony room on days 1, 3 and 5. Either AS oligo or missense (MS) oligo was infused in a volume of 5 microliters over 30 s to freely moving animals. On day 6, the rats were tested. The results showed that icv treatment with an AS oligo against mu opioid receptors, but not an MS oligo against the mu opioid receptor or an AS oligo against the kappa opioid receptor, significantly attenuated the hyperthermia normally produced by a relatively low dose of morphine administered sc. In addition, treatment with an AS oligo against kappa receptors, but not an MS oligo against kappa opioid receptor or an AS oligo against the mu opioid receptor, significantly blocked the hypothermia induced by a high dose of morphine. This study confirms our earlier postulate that morphine at 4 mg/kg, sc, induces an increase in body temperature primarily via mu opioid receptors in the brain and a high dose (30 mg/kg) of morphine administered sc produces a decrease primarily through kappa opioid receptors in the brain.

Molecular basis of proton block of L-type Ca2+ channels

Hydrogen ions are important regulators of ion flux through voltage-gated Ca2+ channels but their site of action has been controversial. To identify molecular determinants of proton block of L-type Ca2+ channels, we combined site-directed mutagenesis and unitary current recordings from wild-type (WT) and mutant L-type Ca2+ channels expressed in Xenopus oocytes. WT channels in 150 mM K+ displayed two conductance states, deprotonated (140 pS) and protonated (45 pS), as found previously in native L-type Ca2+ channels. Proton block was altered in a unique fashion by mutation of each of the four P-region glutamates (EI-EIV) that form the locus of high affinity Ca2+ interaction. Glu(E)-->Gln(Q) substitution in either repeats I or III abolished the high-conductance state, as if the titration site had become permanently protonated. While the EIQ mutant displayed only an approximately 40 pS conductance, the EIIIQ mutant showed the approximately 40 pS conductance plus additional pH-sensitive transitions to an even lower conductance level. The EIVQ mutant exhibited the same deprotonated and protonated conductance states as WT, but with an accelerated rate of deprotonation. The EIIQ mutant was unusual in exhibiting three conductance states (approximately 145, 102, 50 pS, respectively). Occupancy of the low conductance state increased with external acidification, albeit much higher proton concentration was required than for WT. In contrast, the equilibrium between medium and high conductance levels was apparently pH-insensitive. We concluded that the protonation site in L-type Ca2+ channels lies within the pore and is formed by a combination of conserved P-region glutamates in repeats I, II, and III, acting in concert. EIV lies to the cytoplasmic side of the site but exerts an additional stabilizing influence on protonation, most likely via electrostatic interaction. These findings are likely to hold for all voltage-gated Ca2+ channels and provide a simple molecular explanation for the modulatory effect of H+ ions on open channel flux and the competition between H+ ions and permeant divalent cations. The characteristics of H+ interactions advanced our picture of the functional interplay between P-region glutamates, with important implications for the mechanism of Ca2+ selectivity and permeation.

Use of a mu-antisense oligodeoxynucleotide as a mu opioid receptor noncompetitive antagonist in vivo

We examined whether mu-antisense (AS) oligodeoxynucleotide (oligo) treatment can be used in a manner similar to the mu-selective irreversible antagonist beta-funaltrexamine (beta-FNA) for in vivo pharmacology. Rats were injected intracerebroventricularly (icv) with a mu-AS or a missense (MS) oligo on days 1, 3, 5, 7, and 9 and were tested for the antinociceptive effect of sc injection of morphine on days 2, 4, 6, 8, and 10 in the cold water tail-flick (CWT) test. In another set of experiments, rats were also tested for the antinociceptive action of morphine twenty-four hours after icv injection of beta-FNA. Both beta-FNA and mu-AS produced rightward shifts in the dose-effect curves of morphine. In addition, pretreatment with 2.5 micrograms or more of beta-FNA or the mu-AS oligo for 5-9 days (but not for 1-3 days) reduced the maximal analgesic effect of morphine. The approximate fraction of functional receptor remaining for morphine was determined with the method of Furchgott to be 49.5% following 2.5 micrograms of beta-FNA; that after 5 days of the mu-AS oligo treatment was 50.8%. The results suggest that the mu-AS oligo can be used in the same manner as highly selective, irreversible mu opioid receptor ligands. Thus, properly designed AS oligos against receptors are of particular benefit when irreversible antagonists are not available. AS oligos represent a new class of selective and powerful pharmacological antagonists.

Identification of tyrosine 187 as a protein kinase C-delta phosphorylation site

Protein kinase C-delta (PKC-delta) has been demonstrated to be phosphorylated on tyrosine residue(s) in many different biological systems (Li, W., Yu, J.-C., Michieli, P., Beeler, J. F., Ellmore, N., Heidaran, M. A., and Pierce, J. H. (1994) Mol. Cell. Biol. 14, 6727-6735; Li, W., Mischak, H., Yu, J.-C., Wang, L.-M., Mushinski, J. F., Heidaran, M. A., and Pierce, J. H. (1994) J. Biol. Chem. 269, 2349-2352; Denning, M. F., Dlugosz, A. A., Howett, M. A., and Yuspa, S. H. (1993) J. Biol. Chem. 268, 26079-26081). Tyrosine phosphorylation of PKC-delta has also been shown to occur in vitro when purified PKC-delta is coincubated with different tyrosine kinase sources. However, the tyrosine phosphorylation site(s) is currently unknown and the exact effect of this phosphorylation on its serine/threonine kinase activity and biological functions is still controversial. To directly investigate the potential role of PKC-delta tyrosine phosphorylation, tyrosine 187 was converted to phenylalanine (PKC-deltaY187F) by site-directed mutagenesis, and expression vectors containing PKC-deltaY187F cDNAs were transfected into both 32D myeloid progenitor cells and NIH 3T3 fibroblasts. The results showed that tyrosine 187 of PKC-delta became phosphorylated in vivo in response to 12-O-tetradecanoylphorbol-13-acetate stimulation or platelet-derived growth factor receptor activation. In vivo labeling and subsequent two-dimensional phosphopeptide analysis demonstrated that one phosphopeptide was absent in PKC-deltaY187F when compared to wild type PKC-delta, further substantiating that tyrosine 187 of PKC-delta is phosphorylated in vivo. Although the phosphotyrosine content of PKC-deltaY187F was reduced compared with PKC-deltaWT, the kinase activity of PKC-deltaY187F toward a PKC-delta substrate was not altered. Moreover, 12-O-tetradecanoylphorbol-13-acetate-mediated monocytic differentiation of 32D cells was not affected by expression of the PKC-deltaY187F mutant. Taken together, these results suggest that tyrosine phosphorylation of PKC-delta on 187 may not influence PKC-delta activation and known functions.

[Effect of aconitine on content of corticotropin-releasing hormone in hypothalamus of rats]

The effect of aconitine on the content of corticotropin-Releasing-Hormone (CRH) in the hypothalamus of the normal rat injected with aconitine intraperitoneally was studied by means of radioimmunoassay (RIA). Aconitine is the main effective component of Radix Aconiti Carmichaeli Praeparata, the representative traditional Chinese herbal medicine of Warm-Supplementing Kidney-Yang (WSKY). Results showed that the content of hypothalamic CRH menifested a dosedependent increase after 7 days intraperitoneal injection of aconitine (1 microgram/kg, 3 micrograms/kg and 10 micrograms/kg). The CRH neurons in the paraventricular nucleus of hypothalamus and the neural fibers of median eminence also demonstrated increases in number and enrichment in gray tone as observed by immunohistochemical method of ABC. These results suggested that one of the possible mechanism of the WSKY drugs in improving the HPA axis might be exciting the hypothalamic CRH neurons.

An enzymic digestion and solid-phase extraction procedure for the screening for acidic, neutral, and basic drugs in liver using gas chromatography for analysis

Analysis of liver specimens is an important issue in forensic toxicology, but suitable workup and extraction methods for general screening purposes have been lacking until now. A workup and extraction scheme based on a recently developed procedure for the screening of biological fluids was developed that can be used for the screening of acidic, neutral, and basic drugs in liver. This method uses a single solid-phase extraction (SPE) column and gas chromatography-flame ionization detection (GC-FID) for the final analysis. First, the homogenized liver sample is sonicated and centrifuged; the resulting supernatant is applied to the SPE column. Elution of acidic, neutral, and some weakly basic drugs is then performed with acetone-chloroform and analyzed by GC-FID. Next, the pellet of tissue material obtained from the centrifugation is enzymically digested by subtilisin Carlsberg. This frees the drugs bound to the liver tissue. The resulting clear liquid is brought to the reconditioned SPE column. A wash step is introduced to remove acidic and neutral interferences and the basic drugs can then be eluted with ammoniated ethyl acetate. Using 100-mg wet liver samples spiked with 2 micrograms of amounts of various drugs, recoveries were 70-102% with relative standard deviations less than 9%. The resulting GC-FID chromatograms were virtually free of endogenous interferences. GC-nitrogen-phosphorous detection detected smaller amounts of nitrogen-containing drugs, again without endogenous interferences. With the SPE columns currently used, which contain a bed mass of 130 mg, the liver samples should be smaller than 200 mg because the endogenous compounds obtained after the digestion of the tissue will overload the column, which results in a lower recovery of the drugs of interest. Drugs that decompose under the digestion conditions (pH 10.5 at 60 degrees C for 1 h) may be lost in the present procedure. This phenomenon is being investigated further.

Protective effects of tetrandrine on CCl4-injured hepatocytes

AIM

To study the protective effects of tetrandrine (Tet) on CCl4-injured hepatocytes.

METHODS

The cultured rat liver cells were poisoned by CCl4 (10 mmol.L-1). The membrane fluidity was detected by 1,6-diphenyl-1,3,5-hexatriene (DPH), a lipid probe. The Ca2+ concentration was assayed with Fura 2-AM, a sensitive calcium indicator.

RESULTS

Tet (1-1000 nmol.L-1) increased viability of liver cell (from 71% to 72%-89%), reduced lactate dehydrogenase (LDH) release, and malondialdehyde (MDA) formation. Tet prevented the heightening of the intracellular Ca2+ concentration and the attenuation of the membrane fluidity of liver cells (P < 0.05).

CONCLUSION

Tet had a protective effect on CCl4-injured hepatocytes by inhibiting the lipid peroxidation, improving the membrane fluidity, and lessening the Ca2+ concentration.

Localization of sympathetic and parasympathetic neurons innervating pancreas and spleen in the cat

The localization of sympathetic and parasympathetic neurons innervating the pancreas and spleen was studied in the cat utilizing retrograde transport of wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP). Injection of WGA-HRP into the pancreas resulted in retrograde labeling in the whole of the solar plexus, while injection of WGA-HRP into the spleen also resulted in heavy labeling in the celiac ganglia bilaterally. Only a few labeled neurons were distributed in the superior mesenteric ganglion. With respect to parasympathetic innervation, HRP-labeled pancreatic and splenic neurons were found throughout the rostrocaudal extent of the dorsal motor nucleus of the vagus nerve (DMV) bilaterally. Although pancreatic neurons in the DMV were mainly observed in limits rostral to the obex, splenic neurons were centered at the level of the obex.

Electrical stimulation at traditional acupuncture sites in periphery produces brain opioid-receptor-mediated antinociception in rats

Previous studies in rats measuring latency to tail flick with radiant heat have shown that the antinociceptive effect induced by electrical stimulation of different frequencies at traditional acupuncture sites is mediated via different opioid receptors in the spinal cord. The present study was designed to observe (1) whether electrical stimulation at such sites could produce antinociceptive effects in the cold water tail-flick (CWT) test; (2) whether the antinociceptive effects could be blocked by s.c. injection of the opioid receptor antagonist naloxone and (3) whether i.c.v. injection of selective antagonists for mu (cyclic D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2, CTAP), delta (naltrindole) or kappa (nor-binaltorphimine) opioid receptors would block the antinociceptive effect produced by electrical stimulation. Sprague-Dawley rats were stimulated at frequencies of 2, 30 or 100 Hz with acupuncture needles inserted into acupoints Zusanli and Sanyinjiao in the hind leg for 30 min. Antinociception was assayed in the CWT. The results showed that (1) a significant, frequency-related increase in threshold in the CWT was observed in all electrical stimulation groups as compared with the placebo group and the antinociceptive effect lasted about 30 min poststimulation; (2) naloxone (s.c.) antagonized the antinociceptive effect induced by 2 Hz, 30 Hz or 100 Hz electrical stimulation and (3) either CTAP or naltrindole (i.c.v.) almost completely blocked the antinociceptive effect induced by 2 Hz or 30 Hz electrical stimulation, but was less effective in blocking antinociception induced by 100 Hz electrical stimulation; nor-binaltorphimine (i.c.v.) greatly reduced antinociception induced by 30 Hz or 100 Hz electrical stimulation, but not by 2 Hz electrical stimulation. These results indicate that the antinociception induced by 2 Hz electrical stimulation is mediated by both mu and delta opioid receptors; the antinociception induced by 100 Hz electrical stimulation is mediated primarily by the kappa receptor; and the antinociception induced by 30 Hz electrical stimulation is mediated by all three opioid receptor types. Thus, the antinociceptive effect induced by peripheral electrical stimulation, as measured by the CWT, involves opioid receptors in the rat brain.

Morphological demonstration of the immune privilege in the testis using adjuvants: tissue responses of male reproductive organs in mice injected with Bordetella pertussigens

The testis, the epididymis and the prostate are immunologically suppressed organs in which allogeneic tissue grafts can survive for a long time. In the present study, morphological features of these three organs after systemic administration of immunopotentiators was investigated in mice to determine whether or not this treatment can affect their immunosuppressive circumstances. The animals were intravenously injected with adjuvants, Bordetella pertussigens, then killed 7-10 days later for histological examination. The results showed that the testicular interstitium was completely free from leukocyte infiltration but that the accessory glands (the prostate, the coagulating gland and the seminal vesicle), the vas deferens, the epididymis and the ductuli efferentes received extravasation of leukocytes into their interstitial tissues. This indicates that the testis is resistant to leukocyte infiltration compared with the epididymis and the prostate.

Antisense oligodeoxynucleotides against mu- or kappa-opioid receptors block agonist-induced body temperature changes in rats

PL017 and dynorphin A1-17 were shown previously to cause a marked increase and a profound decrease in body temperature (Tb), respectively. In this study, we examined whether an antisense (AS) oligodeoxynucleotide (oligo) against cloned mu or kappa opioid receptors could block PL017- or dynorphin A-induced body temperature changes. Treatment with an AS oligo against mu receptors, but not sense (S) oligo, missense (MS) oligo or artificial cerebrospinal fluid (aCSF), abolished PL017-induced hyperthermia. In addition, treatment with an AS oligo against kappa receptors, but not S oligo, MS oligo or aCSF, greatly attenuated dynorphin A-induced hypothermia. This study further supports the notion that mu and kappa receptors mediate Tb regulation.

Midbrain paralemniscal projections to the facial nucleus: an anatomical and immunohistochemical study

Serial 30 microns-thick sections through the midbrain tegmentum were stained with cresyl violet. The PL was found to be situated along the medial edge of the lateral lemniscus. The PL consisted of small- (10-15 microns) and medium-sized neurons (25-35 microns), and was the most prominent at the caudal level of the superior colliculus. In order to confirm the existence of the inhibitory paralemniscal-facial pathway, a combined HRP and immunohistochemical technique was use in the rat. This experiment revealed that 10.9% of the total number of GABA immunoreactive PL neurons also labeled with HRP after HRP injection was made in the medial part of the facial nucleus (FN). Electron microscopic observations were carried out on the medial part of the facial nucleus (FN) after kainic acid injection was made into the contralateral PL in the cat. The majority of degenerating PL fibers were ranged from 0.5 to 3.1 microns in diameter and made synaptic contacts with somata, proximal dendrites and dendritic profiles. These fibers, containing either round or pleomorphic vesicles, formed asymmetrical or symmetrical synapses. It was of particular interest in the present study that 40.7% of the total number of degenerating fibers make synaptic contacts with large dendrites more than 3.0 microns in diameter.

Ultrastructure of spinal relay of hypoglossal afferents to the parabrachial nucleus

Wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) injection into the hypoglossal nerve mainly resulted in retrograde labeling in the superior ganglia of the glossopharyngeal and vagal nerves ipsilaterally. Anterogradely labeled fibers were found in lamina I of the ipsilateral upper cervical spinal cord with a few distribution to laminae IV-V and VII-VIII. WGA-HRP injection into the PBN revealed intensive labeling of lamina I neurons of the upper cervical spinal cord ipsilaterally. These light microscopic observations appear to indicate the hypoglossal sensory inputs to the PBN through the spinal cord. In order to investigate the synaptic nature of this spinal relay, electron microscopic observations were carried out on lamina I of the first and second cervical spinal cord after cutting the hypoglossal nerve and WGA-HRP injection into the PBN in the same animal. The spinoparabrachial projection neurons were demonstrated to show a low cytoplasmic/nuclear ratio and have an oval or deeply indented nucleus with a centrally located nucleolus. Furthermore, dark and light type degenerating fibers were observed to make synaptic contacts with HRP-labeled somata and dendritic profiles.

Combination gene therapy for liver metastasis of colon carcinoma in vivo

The efficacy of combination therapy with a "suicide gene" and a cytokine gene to treat metastatic colon carcinoma in the liver was investigated. Tumor in the liver was generated by intrahepatic injection of a colon carcinoma cell line (MCA-26) in syngeneic BALB/c mice. Recombinant adenoviral vectors containing various control and therapeutic genes were injected directly into the solid tumors, followed by treatment with ganciclovir. While the tumors continued to grow in all animals treated with a control vector or a mouse interleukin 2 vector, those treated with a herpes simplex virus thymidine kinase vector, with or without the coadministration of the mouse interleukin 2 vector, exhibited dramatic necrosis and regression. However, only animals treated with both vectors developed an effective systemic antitumoral immunity against challenges of tumorigenic doses of parental tumor cells inoculated at distant sites. The antitumoral immunity was associated with the presence of MCA-26 tumor-specific cytolytic CD8+ T lymphocytes. The results suggest that combination suicide and cytokine gene therapy in vivo can be a powerful approach for treatment of metastatic colon carcinoma in the liver.

An antisense oligodeoxynucleotide to mu-opioid receptors inhibits mu-opioid receptor agonist-induced analgesia in rats

We examined effects of an antisense oligodeoxynucleotide against the mu-opioid receptor on mu-opioid receptor agonist-induced antinociception in the cold water (-3 degrees C) tail-flick test in rats. Rats were injected intracerebroventricularly (i.c.v.) with an antisense, sense or missense oligodeoxynucleotide or artificial cerebrospinal fluid on days 1, 3 and 5. On day 6, antinociceptive effects of opioid agonists were tested. Compared to the artificial cerebrospinal fluid treatment, the cumulative dose-effect curve for subcutaneous (s.c.) morphine was shifted to the right by the antisense oligodeoxynucleotide, but not by the missense oligodeoxynucleotide or the sense oligodeoxynucleotide treatment. Antisense oligodeoxynucleotide treatment reduced the analgesic effect of the mu-opioid receptor agonist PL017 ([N-MePhe3,D-Pro4]morphiceptin), but not the delta-opioid receptor agonist BW373U86 ((+/-)-4-((a-R*)-a-((2S*,5R*)-4-allyl-2,5-dimethyl-1-piperazinyl)-3- hydroxybenzyl)-N,N-diethyl-benzamide) or the kappa-opioid receptor agonist spiradoline ((+/-)-(5a,7a,8b)-3,4-dichloro-N-methyl-N-[7-(1- pyrrolidinyl)-1-(oxaspiro-[4,5]dec-8-yl]benzeneacetamide monohydrochloride). The drugs were given by i.c.v. injection. These findings indicate that i.c.v. administration of a mu antisense oligodeoxynucleotide specifically blocks mu-, but not delta- or kappa-opioid receptor-mediated analgesia in the rat cold water tail-flick test.

Hypoglossal afferents to lamina I neurons of the cervical spinal cord projecting to the parabrachial nucleus in the cat

Attempts were made to determine the hypoglossal sensory inputs to the parabrachial nucleus (PBN) through the spinal cord. Wheatgerm agglutinin conjugated to horseradish peroxidase (WGA:HRP) was injected into the cat hypoglossal nerve. HRP-labeled fibers, predominantly derived from the glossopharyngeal and vagal nerves, were observed to terminate in lamina I of the upper cervical spinal cord. A few fibers were also distributed to laminae IV-V and VII-VIII ipsilaterally. WGA:HRP injection into the lateral portion of the PBN also resulted in retrograde labeling in lamina I with ipsilateral predominance. Light-microscopic data raised the possibility of a relay of hypoglossal sensory information to the PBN in lamina I of the cervical spinal cord. In order to confirm the spinal relay, electron-microscopic observations were carried out on lamina I of C1 spinal cord after sectioning of the hypoglossal nerve and WGA:HRP injection into the lateral portion of the PBN on the same side in each animal. It was of particular interest that degenerated hypoglossal afferent fibers made synaptic contacts with lamina I neurons, which were retrogradely labeled with HRP.

A Pit-1 phosphorylation mutant can mediate both basal and induced prolactin and growth hormone promoter activity

The transcription factor Pit-1 has been shown to be important for both the developmental and homeostatic regulation of expression of the PRL and GH genes in pituitary cells. However, little is known about possible covalent modifications in Pit-1 that might mediate its transactivational properties. Previous studies showing that Pit-1 is a phosphorylation substrate for either protein kinase A or C, or their cellular inducers, led us to investigate whether phosphorylation of Pit-1 is required for its function in either basal or induced cellular activity of either the PRL or GH promoters. The transactivational properties of wild type Pit-1 were compared with those of Pit-1(A3), mutated in the three known phosphorylation sites. At saturating levels of Pit-1 expression vectors, activation of transient basal expression in HeLa cells of constructs (-1957)PRL-CAT or (-244)GH-CAT by RSV-Pit-1(A3) was, respectively, about 50% and 65% as strong as by RSV-Pit-1. Hence, phosphorylation at the sites mutated in Pit-1(A3) is not critically required for basal transactivation of either promoter but may modulate this activity. RSV-Pit-1 and RSV-Pit-1(A3) were equally effective in mediating estrogen receptor stimulation of (-1957)PRL-CAT expression in HeLa cells, thus revealing no phosphorylation requirement for the prerequisite for Pit-1 in estrogen receptor action on the PRL estrogen response element.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular cloning and characterization of a novel beta-adrenergic receptor

In an attempt to isolate new G protein-coupled receptors from turkey erythrocytes, reverse transcribed polymerase chain reaction was performed on fetal turkey blood RNA using degenerate primers based on conserved sequences present in seven transmembrane receptors. An open reading frame in one of the clones, designated 4C (497 base pairs), displayed approximately 50-60% identity to all of the previously cloned beta-adrenergic receptors (beta-ARs). A lambda-DASH turkey genomic library was screened with a probe generated from the partial 4C cDNA, and the gene encoding this receptor was localized to a 3.5-kilobase pair HindIII fragment. Ribonuclease protection analysis of turkey lung mRNA indicated that the 3' end of the coding sequence of the 4C gene, like beta 3-AR, was interrupted by an intron. To obtain the cDNA sequence of 4C, RNA-polymerase chain reaction was performed using primers complementary to regions identified by ribonuclease protection analysis to be present in 4C mRNA. Comparison of the genomic and cDNA sequences of 4C indicated that the first exon encodes 414 amino acids of the protein, the second exon (68 base pairs) encodes an additional 12 residues followed by a stop codon, and the third exon is composed of 3'-untranslated sequence. The 4C receptor was transiently expressed in COS-1 cells, and the apparent affinities of a series of beta-AR agonists and antagonists were determined using [125I]iodocyanopindolol. As implicated by its amino acid sequence, 4C displayed a pharmacological selectivity that was consistent with that of a beta-AR but distinct from other cloned beta-ARs. Isoproterenol, epinephrine, and norepinephrine stimulated cyclic AMP accumulation in a concentration-dependent manner in mouse L cells stably expressing the 4C receptor. No effect on phospholipase C activity was observed. Ribonuclease protection assays indicated that 4C mRNA exhibits a broad tissue distribution, which suggests that it may play an important role in avian physiology.

SCM2, a tryptophan permease in Saccharomyces cerevisiae, is important for cell growth

SCM2, a novel gene encoding a yeast tryptophan permease, was cloned as a high-copy-number suppressor of cse2-1. The cse2-1 mutation causes cold sensitivity, temperature sensitivity and chromosome missegregation. However, only the cold-sensitive phenotype of cse2-1 cells is suppressed by SCM2 at high copy. SCM2 is located on the left arm of yeast chromosome XV, adjacent to SUP3 and encodes a 65 kDa protein that is highly homologous to known amino acid permeases. Four out of five disrupted scm2 alleles (scm2 delta 1-delta 4) cause slow growth, whereas one disrupted allele (scm2 delta 5) is lethal. Cells with both the scm2 delta 1 and trp1-delta 101 mutations exhibit a synthetic cold-sensitive phenotype and grow much more slowly at the permissive temperature than cells with a single scm2 delta 1 or trp1-delta 101 mutation. A region of the predicted SCM2 protein is identical to the partial sequence recently reported for the yeast tryptophan permease TAP2, indicating that SCM2 and TAP2 probably encode the same protein.

Determination of basic drugs extracted from biological matrices by means of solid-phase extraction and wide-bore capillary gas chromatography with nitrogen-phosphorus detection

Determination of basic drugs from biological matrices at concentration levels of 100-200 ng/mL was accomplished by using mixed-mode Bond Elut Certify columns and a gas chromatograph equipped with a nitrogen-phosphorus detector. The extraction procedure developed for general drug screening on a GC-FID system was found suitable for the extraction of basic drugs from plasma and whole blood for GC-NPD analysis. For urine samples, an extra wash step with 20% acetonitrile in water was required to obtain clean extracts. The recoveries of 18 basic drugs ranged from 77.7 to 104.5%, with relative standard deviations less than 7.0%.

The microvasculature of human infant oral mucosa using vascular corrosion casts and india ink injection. II. Palate and lip

The microvasculature of human hard and soft palate and lip originating from four infant males and six females, aged 6 months to 2 years was studied by scanning electron microscopy of vascular corrosion casts and light microscopy of India ink injected specimens. The capillary loops of the hard palate mucosa and vermilion border of the lips were found to be tall, numerous and consisted of primary, secondary and tertiary loops. Those of the soft palatal and labial mucosa were short, few in number and demonstrated a simple hair-pin shape originating directly from the subpapillary vascular network. It was concluded that the configuration of capillary loops is not only determined by the shape of the connective tissue papillae in the lamina propria but also influenced by the functional demands characteristic of the different areas of the oral mucosa.

66A-078:a kappa-opiate receptor agonist for amelioration of spinal spasticity

The effect and mechanism of kappa opiate receptor agonist and high-frequency electrostimulation of acupoints in treating spinal spasticity were studied. The spinal spastic models were made by gradual mechanical compression on the cervical spinal cord of rabbits. 24 prepared rabbits were divided into 3 groups randomly, and each group with 8 rabbits was given intrathecally kappa-receptor agonist 66A-078, kappa-receptor antagonist +66A-078 and normal saline respectively. The degree of spasticity was quantified by both clinical score and electrophysiological examinations. The result showed that the spasticity was markedly inhibited by intrathecal injection of 66A-078 and that the kappa-receptor antagonist (naloxone) reversed this effect. We can infer that the antispastic effect of 66A-078 is mediated by kappa-receptors. This result is helpful in explaining the immediate antispastic mechanism of high-frequency electrostimulation of acupoints discussed in previous study.

CCK receptor antagonist L-365,260 potentiated electroacupuncture analgesia in Wistar rats but not in audiogenic epileptic rats

Cholecystokinin octapeptide (CCK-8) has been shown to be a neuropeptide with potent anti-opioid activity. Previous studies have shown that central administration of nanogram dose of CCK-8 totally abolished morphine analgesia in the rat, an effect mediated by CCK-B receptor in central nervous system. In the present study CCK-B antagonist L-365,260 was injected intracerebroventricularly (icv) to Wistar rats to see its effect on the analgesic effect induced by electroacupuncture (EA) stimulation. A marked potentiation of EA-induced analgesia was observed. The degree of potentiation depends on the frequency of EA used, with a rank order of 100 Hz > 15 Hz = 2/15 Hz > > 2 Hz. In a strain of rat with acoustically evoked epileptic seizure (P77PMC rats), an extra-ordinarily strong analgesic effect was produced in response to 100 Hz EA stimulation, which was similar to that in Wistar rats pre-treated with L-365,260. However, L-365,260 was not effective in potentiating EA analgesia in P77PMC rats. The results suggest that (1) high frequency EA is more likely to increase the release of CCK-8 in CNS as compared to low frequency EA, and (2) P77PMC rats may have a functional defect of the central CCK neurons in the nature of either a low CCK content or a reduced rate of release of CCK-8 in the CNS.

Transcutaneous electrical nerve stimulation for treatment of spinal spasticity

Thirty-two patients with spinally originated muscle spasticity were treated with a transcutaneous electrical nerve stimulator, the Han's acupoint nerve stimulator (HANS) via skin electrodes placed over the acupoints on the hand and leg. High frequency (100 Hz), but not the low frequency (2 Hz), stimulation was effective in ameliorating muscle spasticity. While the therapeutic effect lasted for only 10 minutes in the first treatment, it became consolidated after consecutive daily treatment for 3 months. The anti-spastic effect induced by high frequency electrical stimulation can be partially reversed by a high dose of naloxone. The results suggest that the anti-spastic effect elicited by peripheral electrical stimulation is mediated, at least in part, by the endogenous opioid ligand interacting with the kappa opiate receptors, most probably dynorphin, in the central nervous system.

Identification of a P2Y-purinergic receptor that inhibits adenylyl cyclase

Adenine nucleotides inhibited isoproterenol- and forskolin-stimulated cyclic AMP accumulation in C6-2B rat glioma cells. Inhibition occurred in the presence of a phosphodiesterase inhibitor, and no effect of adenine nucleotides was observed in direct measurements of phosphodiesterase activity in intact cells. Pretreatment of C6-2B glioma cells with pertussis toxin blocked the inhibitory effects of P2Y-purinergic receptor agonists. The pharmacological specificity for a series of ATP and ADP analogs (2-methylthioadenosine 5'-triphosphate > or = 2-methylthioadenosine 5'-diphosphate > adenosine 5'-O-(2-thiodiphosphate) > 2-chloro-adenosine 5'-triphosphate = ADP = adenosine 5'-O-(3-thiotriphosphate) > ATP > UTP) was similar to that expected of a P2Y-purinergic receptor; the P2X-purinergic receptor agonists, alpha,beta-methyleneadenosine 5'-triphosphate and beta,gamma-methylene-adenosine 5'-triphosphate, had no effect. Because activation of phospholipase C occurs in response to P2-purinergic receptor activation in many target tissues, the effects of P2Y-receptor agonists on inositol phosphate accumulation were measured in C6-2B cells. No evidence for P2Y-purinergic receptor-mediated regulation of inositol lipid metabolism was observed under conditions where muscarinic cholinergic receptor activation or AIF4-markedly increased inositol phosphate accumulation. These results suggest that a P2-purinergic receptor subtype with distinct signaling properties exists on C6-2B rat glioma cells. Although this receptor expresses the general pharmacological specificity of a phospholipase C-coupled P2Y-purinergic receptor, it may represent a unique receptor subtype since it inhibits adenylyl cyclase.

Pitfalls and solutions in the development of a fully automated solid-phase extraction method for drug screening purposes in plasma and whole blood

A fully automated solid-phase extraction (SPE) method for drug screening is described. The extraction of 19 toxicologically relevant drugs from pretreated plasma and pretreated whole blood was accomplished automatically by a Gilson ASPEC system equipped with disposable 2.8-mL Bond Elut Certify columns. The automated extraction procedure includes 11 fundamental steps: column preconditioning; sample application; column washing; pH adjustment; elution of drugs by two eluents, which were collected into two separated tubes; addition of the chromatographic standard solution; and several SPE column rack movement steps. After evaporation, the drugs were quantitated by gas chromatography. Water was chosen as the transfer liquid in the ASPEC system because it was cheap and, more importantly, because it caused no protein precipitation problem. The effects of the sample and eluent flow rates were investigated, and it was found that low flow rates were necessary to recover the drugs maximally. In the study, the optimal flow rates of sample application, acetone-chloroform elution, and ammoniated ethyl acetate elution were 1.5, 0.72, and 0.33 mL/min, respectively. The absolute recoveries of 19 drugs from whole blood exceeded 82%, with relative standard deviations less than 5% at 2 micrograms/mL.

[Effects of four drugs on intraerythrocytic Plasmodium yoelii of early and late stages]

Erythrocytes of mice infected with Plasmodium yoelii of early stage (ESP) were separated from those infected with late stage (LSP), by a single density-gradient centrifugation in 19% diatrizoate meglumine. After centrifugation, the differential counts of ESP and LSP were 84.9% and 87.4%, respectively. The stage-dependent effects of nitroquine (NQ), pyrimethamine (Pyr), perphenazine (Per) and metronidazole (Met) were studied with [3H]adenosine incorporation into ESP and LSP in vitro using chloroquine (CQ) as control. Like CQ, the 4 drugs inhibited that [3H]adenosine incorporation into LSP more remarkably than that into ESP. The IC50 of CQ, Met, Pyr, Per, and NQ against ESP were 1.89, 2.11, 2.56, 2.60, and 4.65 times as high as that against LSP, respectively.