Brain polyphosphoinositide metabolism during focal ischemia in rat cortex

Using a rat model of stroke, we examined the effects of focal cerebral ischemia on the metabolism of polyphosphoinositides by injecting 32Pi into both the left and right cortices. After equilibration of the label for 2-3 hours, ischemia induced a significant decrease (p less than 0.001) in the concentrations of labeled phosphatidyl 4,5-bisphosphates (66-78%) and phosphatidylinositol 4-phosphate (64-67%) in the right middle cerebral artery cortex of four rats. The phospholipid labeling pattern in the left middle cerebral artery cortex, which sustained only mild ischemia and no permanent tissue damage, was not different from that of two sham-operated controls. However, when 32Pi was injected 1 hour after the ischemic insult, there was a significant decrease (p less than 0.01) in the incorporation of label into the phospholipids in both cortices of four ischemic rats compared with four sham-operated controls. Furthermore, differences in the phospholipid labeling pattern were observed in the left cortex compared with the sham-operated controls. The change in labeling pattern was attributed to the partial reduction in blood flow following ligation of the common carotid arteries. We provide a sensitive procedure for probing the effects of focal cerebral ischemia on the polyphosphoinositide signaling pathway in the brain, which may play an important role in the pathogenesis of tissue injury.

Changes in Schultz-Dale reaction in sensitized canine tracheal smooth muscle

Tracheal smooth muscles from adult dogs 17 to 20 months of age sensitized with ragweed pollen demonstrated a Schultz-Dale phenomenon in response to specific antigen challenge. Seventy percent of the sensitized tracheal smooth muscles developed a Schultz-Dale reaction that consisted only of a phasic response, and the remaining 30% developed a Schultz-Dale reaction that consisted of a phasic component followed by a discrete tonic component. All the Schultz-Dale reactions were mediated only by histamine. The triggering of presynaptic acetylcholine release by histamine during the Schultz-Dale reaction from tracheal smooth muscles of ragweed-pollen-sensitized puppies 6 to 8 months of age was not detected in sensitized adult dogs. Hyperresponsiveness to acetylcholine was detected in tissues from sensitized puppies but not from sensitized adult dogs. Maximal active tension obtained from the sensitized adult canine trachealis during the Schultz-Dale reaction was lower than that obtained from trachealis from sensitized puppies. Dose-response studies showed that sensitized tissues used in the present studies were hyperresponsive to histamine when compared with their nonsensitized control littermates. These results suggest that the nature of the Schultz-Dale response and the identity of the transmitters is age-dependent.

Phosphoenolpyruvate-insensitive phosphofructokinase isozyme from Thermus thermophilus HB8

In the previous paper [Xu, J., Oshima, T., & Yoshida, M. (1990) J. Mol. Biol. 215, 597-606], we reported that phosphofructokinase from Thermus thermophilus is allosterically inhibited by phosphoenolpyruvate, which induces dissociation of the active four-subunit enzyme into an inactive two-subunit form. When T. thermophilus was cultured in a glucose-containing medium, another phosphofructokinase (PFK2) appeared in addition to the reported one (PFK1). The molecular weights of the native PFK2 molecule (132,000) and its subunit (34,500), which are slightly smaller than those of PFK1, suggest that PFK2 is also composed of four identical subunits. However, the hyperbolic kinetics and molecular form of PFK2 are not affected at all by phosphoenolpyruvate. The NH2-terminal amino acid sequences of subunits of PFK1 and PFK2 revealed that they are composed of very similar but different polypeptides.

Localization of the alpha-like globin gene cluster to region q12 of rabbit chromosome 6 by in situ hybridization

The rabbit (Oryctolagus cuniculus) alpha-like globin gene cluster (HBAC) contains several block duplications of zeta-, alpha and theta-globin genes. Using in situ hybridizations to metaphase chromosome spreads, the gene cluster has been mapped to region q12 of chromosome 6. Given that human HBAC maps to the short arm of chromosome 16, the mapping of rabbit HBAC to 6q12 confirms the assignment of homology between OCU6q and HSA16p based on similarities of chromosomal banding patterns. In both species, HBAC is in a very G + C-rich region within the most distal band of the chromosome.

Xanthine oxidase in experimental spinal cord injury

The excessive generation of free radicals is thought to be one of the major mechanisms leading to tissue injury in various pathological conditions, including ischemia, inflammation, and trauma. Conversion of xanthine dehydrogenase (XDH) to xanthine oxidase (XO) contributes to the formation of superoxide, an oxygen radical. We measured XDH and XO activity using a newly developed fluorometric assay in an experimental spinal cord injury model in rats. XO activity increased by more than 100% 4 h after spinal cord trauma. Total (XDH + XO) activity also increased by 96% during the same period. Allopurinol, an inhibitor of XO (100 mg/kg/day x 2 days, i.p.), completely inhibited plasma and spinal cord XO activity but did not affect posttraumatic edema determined by water content or polymorphonuclear (PMN) cell infiltration reflected by myeloperoxidase (MPO) activity in traumatized spinal cord. These results indicate that XDH conversion to XO may not be the major mechanism of oxygen radical formation in the pathogenesis of vasogenic edema or inflammatory response in this experimental spinal cord injury model in rats.

A sensitive fluorometric method for measurement of vascular permeability in spinal cord injury

A sensitive fluorometric method was modified for the evaluation of drug action upon vascular permeability in rat spinal cord injury. Fluorescein isothiocyanate-conjugated dextran (FITC-D MW 71,200), used as a macromolecular tracer, was injected iv 2 hours before sacrifice. The optimal pH for FITC-D fluorescence was 8.2. The recovery in spinal cord was 101.4 +/- 4.0% (mean +/- SD). The extent of FITC-D extravasation, expressed as the vascular injury index (VII), was increased in proportion to the trauma force. The peak of VII after trauma was at 2 hours. This fluorometric method is sensitive, simple, and reliable for evaluation of drug effects upon vascular permeability in CNS trauma.

[Studies on nutrition source of seeds germination of gastrodia elata B1]

The seeds of Gastrodia elata lack an endosperm and other stored nutrition and thus do not easily germinate. Armillaria mellea inhibit germination of the seeds, which exist in a type of symbiotic relationship with fungi. The nutrition necessary for germination is derived from Mycena osmundicola invading cells of the embryo. The tree leaves provide a good medium for Mycena osmundicola growth and an indirect nutritional source for germination.

[Experimental study on cyclosporin A (CsA) acting on rejection of heterolamellar corneal transplantation]

The experiment involved the transfer of lamellar corneas (0.3mm thick and 10mm diameter central epithelium with stroma) from fresh bovine eyes onto rabbits eyes.

RESULTS

group 1, control, (4 rabbits), the donor corneas remained transparent for up to 7-10 days on the recipient rabbit eyes. After that time, all animals in this group rejected their grafts promptly. They showed markedly circumcorneal congestion, edema and vascularization of the cornea. Histopathology: There are apparently cellular infiltration of leukocytes in the grafts, and graft bed of the cornea, which are found also in the iris. Group 2: 3 rabbits were treated with 1% CsA in castor oil, 5 times per day. After 16 days, One of three rabbits showed mild rejection. Group 3: 4 rabbits were treated with CsA, I.M. 15 mg/kg/D. None has any immunological response to the grafts. The histopathology of group 2 and 3 shows no cellular infiltration, except one. CsA can 1. inhibit the rejection of the heterograft. 2. prolong the survive of the heterograft. 3. inhibit the vascularization. 4. has less side effects.

[Effect of phenolic resin fluid on the dentin resistance]

SEM observation was made in the experiment to analyze the ultrastructure of resinified dentin. Phenolic resin fluid permeates in to the dentinal-tubule and set in it. The permeability of this agent was also able to permeate into intercellular substance and changed the appearance of inter-weaved fibril to the condition of agent had set. According to the Fracture Mechanics, it was not beneficial to resist the fracture progress if the microspace had been fulfilled by the agent. The tensile stress of resinified dentin was 387 kg/cm2, which was 30 kg/cm2 lower than that of unresinified-dentin.

Tetramer-dimer conversion of phosphofructokinase from Thermus thermophilus induced by its allosteric effectors

Phosphofructokinase (PFKase) was purified from an extreme thermophile. Thermus thermophilus. Allosteric natures of T. thermophilus PFKase is similar to those of Bacillus stearothermophilus PFKase, that is, hyperbolic plots of the activity versus concentration of fructose 6-phosphate (F6P) were changed into a sigmoidal shape by the addition of phosphoenolpyruvate (PEP), while further addition of ADP caused it to revert to a hyperbolic shape. The native T. thermophilus PFKase has an Mr of 148,000 consisting of four 36,500 subunits. However, it exists as a two-subunit form of Mr 74,000 in the presence of PEP. The two-subunit form was catalytically inactive. The four-subunit enzyme was regenerated by addition of either F6P or Mg.ADP, or by removal of PEP from the solution. This reversible dissociation was observed within a wide range of pH (6.5 to 8.4) and temperature (4 degrees C to 65 degrees C). Thus, unlike PFKase from other sources, the allosteric kinetics of T. thermophilus PFKase can be explained well, at least qualitatively, by the dynamic equilibrium between the active four-subunit form and inactive two-subunit form that is modulated by PEP, F6P and Mg.ADP. Parallel suppression of the PEP-induced conversion in molecular form and kinetics by high concentrations of sulfate and phosphate supports the above explanation. Also, the observation that the degree of PEP inhibition was dependent on the protein concentration of the PFKase in the assay solution is consistent with the presence of this equilibrium.

Identification and characterization of a regulated promoter element in the epidermal growth factor receptor gene

We have identified a 36-base-pair proximal element (-112 to -77 relative to the AUG translation initiation codon) in the epidermal growth factor receptor 5' region that functions as a promoter; mediates inductive responses to epidermal growth factor, phorbol 12-myristate 13-acetate, and cyclic AMP; and acts in an orientation-independent manner. This region functions as an enhancer when transferred to a heterologous promoter containing a TATA box. Mutations within the 36-base-pair region alter function as assayed by reporter gene expression in recipient cells. A protein has been identified that demonstrates appropriate binding specificity to mutant DNA sequences that correlates with promoter activity observed in vivo. On the basis of DNA binding characteristics and size, the identified protein appears distinct from several previously identified transcription factors known to bind to G+C-rich regions.

[Cytological observation on hyphae invading Mycena osm undicola in the process of seed germination of Gastrodia elata Bl]

In order to obtain the nutrition necessary to sprout, Gastrodia elata seeds depend on digesting a kind of fungi (Mycena osmundicola Lange). Hyphae are enclosed and digested by embryonic cytoplasm after M. osmundicola penetrates the embryo through suspensor cells, and then meristem cells begin to divide. The digested hyphae penetrate into large cells to be further digested. The body of the embryo then enlarges and germinates under meristem cells using the nutrition thus obtained.

[A simplified polygraphic method for studying sleep in the rat]

Experiments were performed on 10 healthy Wistar rats with chronically implanted electrodes for the recording of electrocorticogram (ECoG), electro-oculogram (EOG), and electromyography (EMG). All the rats were prepared for the implantation of recording electrodes under 5% Ketamine (100 mg/kg i.p.) anesthesia. Four to six days after operation, the rat was put in an apparatus which was designed specifically sensitive to detect the movement of the animal without electrode on the body so that electroactogram (EAG) could be recorded readily. One group of experiment animal (n = 5), recorded ECoG, EAG, EOG and EMG simultaneously, was compared to another group (n = 5), recorded ECoG and EAG simultaneously. The results of experiments indicate that the ECoG, recorded from the the mesial frontal and occipital areas, have certain characteristics during different sleep phases, and the characteristics for classifying sleep phases by the two kinds of somnopolygram are similar. Therefore, simultaneous recording of the ECoG and EAG can be used to discriminate the sleep phases in the rat. In this way, the somnopolygraphic recording method for studying sleep in the rat would be simplified.

[Effects of fungi and its liquid extract on seed germination of Dendrobium hancockii Rolf]

The experiment revealed that several species of fungi isolated from the protocorms of Orchidaceae notable promote the seed germination of Dendrobium hancockii. The seed germination rate amounts to over 20% when the seeds are incubated with fungi, but zero without incubation. Seed germination rate ranges from 40 to 70% when the incubation is affected in liquid extract of the cultural products of fungi, but the growth of protocorms and seedlings of Dendrobium hancockii is slower in liquid extract of fungi than on mycolia.

[Determination of primary metabolic products of fungi promoting seed germination of Gastrodia elata Bl. and other Orchidaceae medicinal plants]

The contents of amino acids, protein, water-soluble sugar, reducing sugar and microelements in seven strains of seed-germination-promoting fungi were determined. It was found that the contents of primary products were different in these fungi. In the light of physiological characteristics of seed germination, the action mechanism of the products in promoting seed germination was discussed.