Interaction of pergolide with central dopaminergic receptors

The activity of pergolide, an N-propylergoline derivative, has been tested for stimulation of central dopaminergic receptors. Binding to dopamine receptors shows that pergolide acts as an agonist with respect to these receptors. GTP decreases the potencies of dopamine agonists and of pergolide, but not of bromocriptine, to displace [3H]spiroperidol ([3H]Spi) from striatal membrane sites. The GTP-sensitive site labeled by [3H]Spi seems to be localized on intrastriatal dopamine receptors. The potency of dopamine agonists and of pergolide to displace [3H]Spi from striatal receptor sites is reduced in membranes exposed to higher temperatures. Pergolide, but not hitherto-tested dopaminergic ergots, stimulates dopamine-sensitive adenylate cyclase in striatal homogenates. Thus, pergolide, unlike other dopaminergic ergots, acts as an agonist on GTP-sensitive components of [3H]Spi binding and stimulates dopamine receptors linked to dopamine-sensitive adenylate cyclase. The drug also induces turning behavior in rats with 6-OH-dopamine lesions and relieves tremor in monkeys with ventromedial tegmental lesions for a longer time at a lower dose than other tested dopaminergic ergots. Other studies have shown that it is effective in the treatment of patients with advanced parkinsonism.

Estimation of in vivo digestibility with the laying hen by an in vitro method using the intestinal fluid of the pig

1. Dry matter and crude protein (nitrogen x 6.25) digestibility of four poultry diets determined by an in vitro method using the intestinal fluid of pigs was significantly correlated with corresponding in vivo digestibility values obtained with hens. 2. The intestinal fluid could be lyophilized and stored for at least 35 d without losing its activity on digestion.

Lipid peroxidation as a cause of cerebral vasospasm

In the present study, the vasocontractile activities of purified oxyhemoglobin, methemoglobin, peroxides of linoleic and arachidonic acid, and hydrogen peroxide were examined in vitro, using the canine basilar artery. It was shown that all of them possess a vasocontractile capacity in a dose-dependent fashion. Fresh canine arterial blood was incubated at 37 degree C for 2 weeks, and the daily change of its vasocontractile capacity and the amount of TBA-reactive substance was studied. This study revealed a gradual and parallel increase in both of them. In a clinical study with 32 SAH patients, the amount of TBA-reactive substance in the CSF was more elevated when angiographically confirmed vasospasm was present. The angiographical and histological responses of the basilar artery to the cisternal injection of 15-HPAA were studied in dogs. The cisternal injection of 15-HPAA (0.2 and 2.0 mg dissolved in bovine serum) caused a mild initial contraction of the basilar artery that lasted about 7 hours. On the third day, a stronger contraction occurred, persisting thereafter until sacrifice. Electronmicroscopy of those arterial samples revealed the disappearance of myofibrils, pyknotic changes of nuclei, and the appearance of vacuoles as well as electron-dense granules in the tunica media. The prolonged arterial contraction was always associated with remarkable destruction of the endothelial cells. These changes were essentially the same as those in experimental and clinical vasospasm. These data strongly indicate that free radical reactions initiated by clot lysis, represented by lipid peroxidation, plays an important role in the genesis of chronic vasospasm in subarachnoid hemorrhage.

Increase of serum high density lipoprotein with progression and regression of aortic lipid deposition in rats

The progression and regression of aortic lipid deposition was studied in male ExHC rats. Rats in the progression group were fed an atherogenic diet containing 2% cholesterol, 0.4% sodium cholate and 10% olive oil for periods up to 32 weeks. Rats in the regression group were first fed the atherogenic diet for 16 weeks, and then maintained on a basal low cholesterol diet. Half the rats were killed at 4 weeks and the other half at 16 weeks after cessation of the atherogenic diet. Rat aortas of the progression group contained progressively more lipid pari passu with the duration of cholesterol feeding, but connective-tissue proliferation was absent. Deposited lipid in the aorta of cholesterol-fed rats disappeared very slowly after the rats were returned to the basal diet. serum HDL decreased in the hypercholesterolemic ExHC rats fed the atherogenic diet for 4 weeks. By contrast, serum HDL and apo A-I increased in both hypercholesterolemic ExHC rats fed the atherogenic diet for 32 weeks and slightly hypercholesterolemic ExHC rats fed the basal diet for 16 weeks in the regression period.

Induction of unresponsiveness to major transplantable organs in adult mammals: a recapitulation of ontogeny by irradiation and bone marrow replacement

Transplantation of renal allografts obtained from prospectively selected genotypically DLA-identical donors into supralethally irradiated dogs reconstituted with their own stored bone marrow has produced a state of unresponsiveness to these kidneys in the recipients. Eleven of 18 kidneys transplanted at 12 hours after marrow replacement currently survive with normal function and maintain life in the recipients for 757, 800, 825, 978, 1062, 1092, 1136, 1282, 1373, 1380, and 1381 days, respectively. Similar results occurred in eight of 13 allografts transplanted at 28 hours after marrow replacement, which currently survive for 349, 363, 377, 407,436,470, 485, and 513 days, respectively, and in eight of 13 kidneys grafted at 36 hours after marrow replacement, which are surviving for 197, 247, 298, 324, 337, 396, 443, and 472 days, respectively. Achievement of optimal results is dependent on the specific timing and sequence of each procedure. Only four of 16 recipients of kidneys transplanted at the time of marrow replacement were unresponsive to their allografts. Similarly, only five of 19 recipients of kidneys placed in irradiated dogs at 40 hours before marrow replacement accepted such allografts. When kidney transplants were placed into the recipients 20 hours before removal of marrow, irradiation, and reconstitution with stored marrow, only three of 21 dogs became unresponsive to such ailografts. In five of 12 instances, the recipients were also unresponsive to skin allografts obtained from their respective kidney donors. Such skin grafts currently survive for 606, 673, 687, 701, and 708 days, respectively. The remaining seven skin grafts were rejected at 28, 39,42, 84, 90, 92, and 115 days, respectively. Second- and third-set skin grafts from the same kidney donor were rejected by six of these dogs at 19, 20, 21, 29, 29, and 30 days, and at 21, 22, 23, 24, 27, and 27 days, respectively. Rejection of these skin grafts had no detectable effect on the function and survival of kidney allografts from the same source. Seven of eight skin grafts obtained from other DLA-identical donors were rejected at 13,14,16,25,28,38, and 84 days, respectively; one allograft continues to survive for 708 days. Eleven DLA-incompatible skin allografts placed on the recipients at the same time were rejected within 11-20 days. Supralethal total body irradiation and bone marrow replacement can establish in the adult canine host a privileged phase of immunological reactivity during which exposure to alloantigens produces specific long-term unresponsiveness rather than sensitization. The use of stored autologous rather than allogeneic bone marrow for reconstitution of the irradiated recipient eliminates the hazards of GVH complication usually associated with this procedure. This consideration and the apparent capacity of the tolerant host to maintain a long-term state of unresponsiveness without any further immunosuppressive therapy point to the potential relevance of the results to human transplantation.

Protection from cerebral ischemia by a new imidazole derivative (Y-9179) and pentobarbital. A comparative study in chronic middle cerebral artery occlusion in cats

For the purpose of investigating the protective action against cerebral ischemia by a new imidazole derivative (Y-9179) and pentobarbital, regional cerebral ischemia was produced in 53 cats by permanent occlusion of the middle cerebral artery (MCA) via the transorbital approach. In 20 cats, the clips were applied at the origin of the right MCA whereas in the remaining 33 they were applied laterally. The administration of Y-9179 (6.25 and 12.5 mg/kg/day), pentobarbital (25 mg/kg/day) and saline was started 30 min after MCA occlusion and continued for 3 days. The cats were observed for 7 days and then sacrificed. Since there was a remarkable difference in mortality between the medial (65%) and the lateral occlusion groups (15%), the evaluation of drug effects was based only on the results obtained with the lateral occlusion group. The brains were sliced at 4 fixed coronal planes, in which the ratios of the infarcted area in the 2 hemispheres were obtained by planimetry. A statistically significant decrease in the infarction rate was found both in Y-9179 and pentobarbital-treated groups compared to the control group. Since the CNS depressant action of Y-9179 is far less potent than that of pentobarbital, the present results indicate the potential usefulness of Y-9179 in the management of strokes.

Identification of inosine and hypoxanthine as endogenous ligands for the brain benzodiazepine-binding sites

Two endogenous ligands for the brain benzodiazepine-binding sites were isolated from bovine brain through gel filtration, paper electrophoresis, and paper chromatography. These ligands were identified as inosine and hypoxanthine, and both had a higher affinity for the brain benzodiazepine-binding sites than for benzodiazepine sites in some peripheral tissues. They did not bind to any other receptors tested, such as the opiate, muscarinic cholinergic, gamma-aminobutyric acid, and beta-adrenergic receptors. Both inosine and hypoxanthine competitively inhibited the binding of [3H]diazepam to the brain binding site.

Insulin delivery rate in response to glucose infusion in normal and diabetic subjects

The insulin delivery rates were estimated in 8 normal and 8 diabetic subjects from the results of peripheral insulin response to a single bolus iv injection of glucose, taking account of fractionally removed insulin. The delivered insulin response to 0.5 g/Kg body weight of glucose injection was biphasic in normal and diabetic subjects. In normal subjects, 1.7 +/- 0.3 U of insulin was delivered during the first phase (0-10 min) and 5.6 +/- 1.6 U during the second phase (11-60 min). In diabetic subjects, 0.4 +/- 0.2 U of insulin was delivered during the first phase and 1.8 +/- 0.5 U during the second phase. The amounts of delivered insulin during the first and second phases were significantly decreased in diabetics (p less than 0.01). The insulin delivery rates during the first and second phases fitted by the same line to the glucose concentration at each period. This suggests that a common glucoreceptor or glucose-mediated signal of the insulin response might exist during both phases. The glucose-insulin response curves in mild diabetics seemed to be similar to those in the normals, but shifted toward higher glucose levels. This finding suggests that the decreased glucose sensitivity of pancreatic beta cells in mild diabetics can be corrected by high glucose concentrations.

Characterisation of the effect of intravenous infusion of glucose and tolbutamide on the insulin delivery rate in man

Serum insulin response to a single bolus of IV glucose or tolbutamide was measured in eight healthy subjects. Insulin disappearance rate was assessed by deconvolution from the serum insulin levels, using the measured insulin disappearance rate. The mean rate constant of insulin disappearance was 0.238 +/- 0.005 min-1 (mean +/- SEM). Basal insulin delivery rate was 8.0 to 9.0 mU/min and the delivery rate following glucose injection (0.5 g/kg body weight) showed a biphasic response, whereas that after tolbutamide injection (15.6 mg/kg body weight), a monophasic response. After glucose injection, 1.7 +/- 0.3 U of insulin was delivered during the first phase (0--10 min) and 5.6 +/- 1.6 U during the second phase (11--60 min). After tolbutamide injection, 1.5 +/- 0.3 U of insulin was delivered during the first 10 min. Between 11 and 40 min, 1.6 +/- 0.5 U of insulin was delivered. The results thus confirm and also quantitate biphasic insulin secretion after a bolus of glucose with a monophasic response after tolbutamide. The method is suitable for studies of the insulin secretogogues in man.

[Measurement of spinal cord blood flow in rabbits: central gray matter flow and CO2 reactivity (author's transl)]

Spinal cord blood flow (SCBF) was measured in 20 rabbits anesthetized with sodium pentobarbital. The platinum electrodes (0.3 mm in diameter) were inserted into the central gray matter of the thoracic spinal cord (Th8-10). In all animals, blood pressure and pAO2 remained constantly in the normal range. The pACO2 was changed by ventilation. Blood gases were checked both before and after each spinal cord blood flow measurement. The results are as follows. 1. Seventy-three percent of the clearances recorded from the gray matter were monoexponential and in the white matter almost all were monoexponential. 2. The mean values of gray matter SCBF of all animals was 38.3 +/- 1.85 ml/100 g/min (SE) at normo-capnea and the white matter was 19.5 +/- 1.33 ml/100 g/min. 3. An almost linear relationship exists between the pACO2 and SCBF. The values were 0.62 ml/100 g/min/torr in the gray matter and 0.38 ml/100 g/min/torr in the white matter.

Platelet aggregation and cyclic nucleotide phosphodiesterase activity in arteriosclerotic patients

Although roles of roles of cyclic AMP and cyclic GMP in platelets are though to be important on platelet aggregation, little information on their phosphodiesterase (PDE) is available. Cyclic AMP and cyclic GMP hydrolytic activities of platelets (cAMPPDE and cGMPPDE in platelets) and platelet aggregation by ADP and adrenaline were measured in 22 healthy volunteers, 26 arteriosclerotic patients and other 20 miscellaneous patients excluding vascular diseases. Activities of cAMPPDE and cGMPPDE of platelets were 2.37 +/- 0.52, 7.23 +/- 1.84 in the healthy, 2.50 +/- 0.85, 7.53 +/- 2.60 in the arteriosclerotics and 2.38 +/- 1.02, 6.98 +/- 2.59 pmol/min/10(7) platelets in the miscellaneous patients, respectively. No significant difference was observed among these three groups. Platelet aggregabilities also showed no significant difference. However, there was a significant inverse correlation between the aggregability by 1 microgram/ml of adrenaline and the PDE activities only in the arteriosclerotic patients. The correlation coefficient were-0.61 between the primary aggregation and cAMPPDE,-0.65 between the primary aggregation and cGMPPDE,-0.58 between the 5 min aggregation and cAMPPDE and -0.76 between the 5 min aggregation and cGMPPDE. The inverse correlation between platelet aggregation and cyclic nucleotide metabolism in circulating platelts of the arteriosclerotic patients may suggest that interaction of platelets with arteriosclerotiv vessel walls would produce a certain change in platelets.

Cyclic 3':5'-nucleotide phosphodiesterase determined in various human tissues by DEAE-cellulose chromatography

Tissue extracts from human heart, lung, liver, kidney, skeletal muscle and cerebrum displayed at least 3 distinct cyclic 3':5'-nucleotide phosphodieterase (EC 3.1.4.17) activity peaks (FI, FII, FIII) on DEAE-cellulose chromatography and various properties of these forms were compared in each tissue. FI eluted at about 0.08 M sodium acetate, hydrolyzed cyclic GMP more rapidly than it did cyclic AMP, and cyclic GMP hydrolysis by FI in most tissues was enhanced by a protein activator in the presence of CaCl2. As only high concentrations of cyclic AMP inhibited cyclic GMP hydrolytic activity of FI, the enzyme probably has a low affinity for cyclic AMP. FII eluted at about 0.2 M sodium acetate, hydrolyzed both nucleotides at equal rates, and substrate affinities were relatively low. Cyclic GMP hydrolysis by FII was also stimulated by addition of a protein activator in the presence of CaCl2 and cyclic AMP hydrolysis in this fraction was accelerated by a micromolar fraction of cyclic GMP. FII eluted at about 0.35 M hydrolyzed cyclic AMP preferentially and was insensitive to protein activator. These two cyclic nucleotides act as mutual inhibitors of the hydrolysis in this fraction. Ratio of the cyclic GMP to cyclic AMP hydrolysis was in the order FI, FII, FIII. Four activity peaks were eluted from the cerebral extract and enzymes from this tissue exhibited much the same properties as observed in the other tissues examined herein.

Stimulation of human platelet guanylate cyclase by unsaturated fatty acid peroxides

Guanylate cyclase [GTP pyrophosphate-lyase (cyclizing), EC 4.6.1.2] activity of human platelet homogenates was stimulated by the addition of phospholipase A2 or unsaturated fatty acids such as oleic, vaccenic, linoleic, linolenic, eicosenoic, eicosadienoic, and arachidonic acids. The addition of lipoxidase potentiated the fatty acid-induced stimulation of guanylate cyclase purified by DEAE-cellulose column chromatography. The extent of the stimulation was dependent on the concentration of the oxidized form of these fatty acids (peroxides). Saturated fatty acids such as stearic and arachidic acids had no effect on the guanylate cyclase activity in the presence or absence of lipoxidase, indicating that human plateletguanylate cyclase is stimulated by unsaturated fatty acid peroxides rather than by fatty acids. Hemoglobin prevented the enzyme stimulation produced by low concentrations of fatty acid peroxides, but enhanced stimulation of the enzyme activity with high concentrations of fatty acid peroxides. 2-Mercaptoethanol, dithiothreitol, and N-ethylmaleimide inhibited the guanylate cyclase activities both in the presence and absence of unsaturated fatty acidperoxide. The stimulation of guanylate cyclase activity by unsaturated fatty acid peroxidesis attributed to oxidation of sulfhydryl residues of the enzyme protein.

Resistance of germfree rats to indomethacin-induced intestinal lesions

Indomethacin given orally to conventional rats produced in three days a syndrome, often fatal, of intestinal lesions characterized by multiple ulcers and peritonitis. Male germfree rats were found to be resistant to this effect of indomethacin, while female germfree rats developed very mild lesions. Germfree rats became sensitive again to such lesions when monocontaminated with E. coli. In such animals, however, the lesions were less severe than in conventional animals, presumably because more than one microorganism is necessary for the full syndrome to develop. These results suggest that microorganisms are necessary for the development of indomethacin-induced intestinal lesions. Secondary bile acids, absent in germfree animals, may also be necessary. The prostaglandin deficiency caused by indomethacin appears to weaken the resistance of the intestinal mucosa to microorganisms and/or their toxins. The latter may then penetrate the mucosa, damage the cells and produce ulcers and perforations. Since several prostaglandins also protect against indomethacin-induced lesions, the hypothesis is advanced that certain prostaglandins may protect the mucosa ("cytoprotection") by preventing the spread of microorganisms and/or their toxin through the intestinal wall.

Pathogenetic role of no-reflow phenomenon in experimental subarachnoid hemorrhage in dogs

The real pathogenetic role of no-reflow phenomenon in clinical situations such as the acute stage of subarachnoid hemorrhage (SAH) is not yet known. To study this problem, we carried out the following experiment in dogs: SAH was induced by withdrawing a needle previously inserted into the internal carotid artery through a small craniectomy in the lateral base of the skull. Complete dural repair and cranioplasty was done to avoid cerebrospinal fluid leakage. Cortical cerebral blood flow (CBF) changes, measured by a double-needle type thermocouple, intracranial pressure (ICP), electroencephalogram (EEG), and sensory evoked response were monitored under controlled ventilation of 3 hours after SAH. At the end of the experiment, the brain was perfused with carbon black solution at a pressure of 120mm Hg. The 32 episodes of SAH thus induced yielded two basic patterns of ICP changes which simulated those previously reported with human SAH. In the first pattern, reactive hyperemia was always observed, followed by complete or incomplete recovery of cerebral function. Perfusion defects were frequently seen in the thalamus, basal ganglia, and parietooccipital cortex symmetrically. In the second pattern, prolonged elevation of ICP resulted in failure of recovery of both CBF and EEG. Carbon black filled only the pial arteries and the rest of the brain was totally unperfused. From the results, the pathogenetic role of the no-flow phenomenon in the acute stage of SAH as influencing the prognosis is strongly suspected.

Xylitol, a partial homologue ot alpha-D-glucopyranose: potent stimulator of insulin release in dogs

A direct comparison was made in healthy female dogs of the potency of xylitol and mutarotated glucose as stimulators of insulin release (both first and second phases), and also of their urinary excretion and arterio-venous difference across a hind-limb. Xylitol or glucose was given by constant infusion into a systemic vein for 50 minutes in paired experiments. Three dose levels were used in 12 dogs. Plasma insulin levels during xylitol infusion were as high as or higher than those during glucose infusion, with increases in arterial xylitol levels equal to or less than those in glucose. More xylitol was lost in the urine, but the overall uptake of xylitol was at least 70% also the arteriovenous difference for xylitol across the hind-limb was greater than for glucose, when each was divided by the arterial sugar concentration. It is suggested that both the striking potency of xylitol in stimulating both phases of insulin release, and its rapid uptake by tissues, may result from its homology with alpha-D-glucopyranose, the alpha-anomer of glucose. The concept of a glucoreceptor on the surface of the pancreatic beta-cell, with stereospecificity for alpha-D-glucopyranose or closely similar molecules, is supported by our results.

Adaptive properties of the b-wave and the PIII in the perfused isolated carp retina

1. Perfusion of isolated carp retina with a pure oxygen saturated standard solution used in this experiment permitted several continuous hours of ERG recordings showing a distinctive b-wave as well as the PIII isolated by sodium aspartate. 2. The dark-adapted threshold for the PIII required an absorption of 5 to 6 quanta per rod. The 'rod-cone break' in the increment threshold curve for the b-wave was induced at a background intensity of about 2.0 X 10(-2) muW/cm2. 3. Both the b-wave and the PIII showed rapid and complete recovery of sensitivity after exposure to dim adapting lights. After bright light adaptation, the sensitivities went through a short 'fast phase' followed by a prolonged 'slow phase' of recovery. The rate of recovery during the fast phase was significantly faster for the PIII than for the b-wave. Neither a lowered temperature (9 degrees C) nor the application of ouabain (10(-6) M) influenced the fast phase. This seems to prove that the visual pigment, photoproducts and the active transport hardly participate in its mechanism, if at all. 4. The prolonged slow phase that followed the fast phase was distinguished by the recovery of the rod activity, even in isolated retinas.

Platelet cyclic 3':5'-nucleotide phosphodiesterase released by thrombin and calcium ionophore

Contact of rat platelets with thrombin or the divalent cation ionophore A-23187, in the presence of extracellular calcium, resulted in the secretion of adenosine 3':5'-monophosphate (cyclic AMP) and guanosine 3':5'-monophosphate (cyclic GMP) phosphodiesterases. Significant association of calcium with platelets occurred during platelet surface contact with thrombin. Thrombin concentration to induce association of calcium virtually agreed with that to release the enzyme. The finding that A-23187 (5 to 20 muM) also provoked a rapid and marked association of extracellular calcium with platelets suggests that calcium mobilization into the intracellular environment may account, at least in part, for this association between platelet and calcium. Two different phosphodiesterases, a relatively specific cyclic AMP and a relatively specific cyclic GMP phosphodiesterase were secreted from platelets into the plasma in soluble form. The amounts of the phosphodiesterases secreted were dose- or time-dependent on thrombin (0.1 to 2 units) or A-23187 (5 to 20 muM) within 30 min. The enzyme release by thrombin was completely inhibited by heparin but the release by A-23187 was not. The two phosphodiesterases secreted seemed to correspond to the two enzymes isolated from platelet homogenates in many respects. Rat platelets contained, at least, three cyclic 3':5'-nucleotide phosphodiesterases, namely, two relatively specific cyclic AMP phoshodiesterases and a relatively specific cyclic GMP phosphodiesterase which were clearly separated from each other by Sepharose 6B or DEAE-cellulose column chromatography or sucrose gradient centrifugation. The two platelet cyclic AMP phosphodiesterase (Mr = 180,000 and 280,000) had similar apparent Km values of 0.69 and 0.75 muM with different sedimentation coefficient values of 4.9 S and 7.1 S, respectively. They did not hydrolyze cyclic GMP significantly. A cyclic GMP phosphodiesterase (Mr - 260,000) exhibited abnormal kinetics for cyclic GMP with an apparent Km value of 1.5 muM and normal kinetics for cyclic AMP with a Km of 300 muM. The properties of a platelet cyclic AMP phosphodiesterase (Mr = 180,000) and a platelet cyclic GMP phosphodiesterase were found to agree with those of the two phosphodiesterases released from platelets by thrombin or A-23187. Depletion of extracellular calcium by an addition of citrate, EDTA, or ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA) to the blood or platelet suspension resulted in a loss of the activity of the smaller form of platelet cyclic AMP phosphodiesterase (Mr = 180,000) and addition of calcium restored the activity of this cyclic AMP phosphodiesterase. Thus, calcium seemed to be involved in the mechanism of an occurrence of this smaller form of cyclic AMP phosphodiesterase as well as the secretion of this enzyme. Contact of human platelets with thrombin also resulted in the secretion of cyclic nucleotide phosphodiesterase which was dependent on the concentration of calcium. No species difference was observed in this respect.

Human blood platelet 3': 5'-cyclic nucleotide phosphodiesterase. Isolation of low-Km and high-Km phosphodiesterase

Human blood platelet contained at least three kinetically distinct forms of 3': 5'-cyclic nucleotide phosphodiesterase (3': 5'-cyclic-AMP 5'-nucleotidohydrolase, EC 3.1.4.17) (F I, F II, and F III) which were clearly separated by DEAE-cellulose column chromatography. Although a few properties of the platelet phosphodiesterases such as their substrate affinities and DEAE-cellulose profile resembled somewhat those of the three 3': 5'-cyclic nucleotide phosphodiesterase in rat liver reported by Russell et al. [10], there were pronounced differences in some properties between the platelet and the liver enzymes: (1) the platelet enzymes hydrolyzed both cyclic nucleotides and lacked a highly specific cyclic guanosine 3': 5'-monophosphate (cyclic GMP) phosphodiesterase and (2) kinetic data of the platelet enzymes indicated that cyclic adenosine 3': 5'-monophosphate (cyclic AMP) and cyclic GMP interact with a single catalytic site on the enzyme. F I was a cyclic nucleotide phosphodiesterase with a high Km for cyclic AMP and a negatively cooperative low Km for cyclic GMP. F II hydrolyzed cyclic AMP and cyclic GMP about equally with a high Km for both substrates. F III was low Km phosphodiesterase which hydrolyzed cyclic AMP faster than cyclic GMP. Each cyclic nucleotide acted as a competitive inhibitor of the hydrolysis of the other nucleotide by these three fractions with Ki values similar to the Km values for each nucleotide suggesting that the hydrolysis of both cyclic AMP and cyclic GMP was catalyzed by a single catalytic site on the enzyme. However, cyclic GMP at low concentration (below 10 muM) was an activator of cyclic AMP hydrolysis by F I. Papaverine and EG 626 acted as competitive inhibitors of each fraction with virtually the same Ki value in both assays using either cyclic AMP or cyclic GMP as the substrate. The ratio of cyclic AMP hydrolysis to cyclic GMP hydrolysis by each fraction did not vary significantly after freezing/thawing or heat treatment. These facts also suggest that both nucleotides were hydrolyzed by the same catalytic site on the enzyme. The differences in apparent Ki values for inhibitors such as cyclic nucleotides, papaverine and EG 626 would indicate that three enzymes were different from each other. Centrifugation in a continuous sucrose gradient revealed sedimentation coefficients F I and II had 8.9 S and F III 4.6 S. The molecular weight of these forms, determined by gel filtration on a Sepharose 6B column, were approx. 240 000 (F I and II) and 180 000 (F III). F III was purified extensively (70-fold) from homogenate, with a recovery of approximately 7%.

The size pH, and redox potential of the cecum in mice associated with various microbial floras

Cecal size and in situ redox potential and pH of cecal contents were determined in conventionally reared mice and mice reared under a variety of gnotobiotic conditions: germfree, monoassociated with a cecal Clostridium sp., hexaflora-associated and thermoduric polyflora-associated. The mean Eh was approximately +200 mV in germfree and -200 mV in conventional mice. The Eh was close to zero in the monoassociated mice, thus occupying a position intermediate between the germfree and conventional mice. The potentials observed in the hexaflora and the thermoduric flora groups were indistinguishable from those of conventional animals. The degree of normalization was more advanced with respect to the redox potential than to the cecal size in the various gnotobiotic groups. In the thermoduric polyflora-associated group, normalization was observed in both cecal size and redox potential. This demonstrates that normalization can be accomplished with a relatively simplified microflora, at least with regard to the parameters studied.

Long-term follow-up results of bilateral thalamotomy for parkinsonism

27 patients who underwent bilateral thalamotomy for parkinsonism over the past 10 years have been clinically evaluated. Mean follow-up period was 6.2 years after second surgery. In these cases, 8 returned to full social life without any medication, 4 were capable of social life with medical treatment, 6 were self-sufficient and 3 were semi-self-sufficient in ADL, respectively. Therapeutic drug doses were reduced in all cases. L-Dopa-induced dyskinesia was not observed after second surgery. Speech disturbance, which was not severe, was recognized in 12 cases as a complication.

Readiness potentials recorded from the scalp and depth leads

Readiness potentials on voluntary hand movements were recorded from the scalp (C3, C4), premotor cortex, subcortical white matter and VL nucleus of the thalamus. Subjects were healthy right-handed men and patients with involuntary movement disorders. We obtained a slow negative shift of brain electrical potentials from the scalp and cortex preceding voluntary hand movements. The mean time interval between the onset of the readiness potential and the onset of motor activity (mean T) was 0.8 sec on right hand movements and 1.0 sec on left hand movements in healthy men. In cases with parkinsonism, the mean T value was 1.4 sec in patients with akinesia, 1.1 sec in those without akinesia. The amplitude of readiness potentials was higher in the scalp contralateral to the hand movement. The readiness potentials recorded from the VL nucleus and white matter were reversed in polarity from those of scalp and cortex. Simultaneous recordings from cortex and VL nucleus showed early onset of readiness potentials from the cortex by approximately 0.1 sec compared with the VL nucleus.

Effects of cholestyramine on 1,2-dimethylhydrazine-induced enteric carcinoma in germfree rats

Oral administration of 1,2-dimethylhydrazine (DMH) induced intestinal neoplasms in germfree rats. A supplement of 2% cholestyramine resin in the diet increased the frequency of DMH-induced intestinal tumors and accelerated malignant transformation. Bile acids in the cecal content were determined with and without cholestyramine in order to obtain a correlation between the bile acid metabolism and the enteric carcinogenesis.