Mucosal lesions of the stomach in liver cirrhosis with a special reference to phospholipid metabolism

Gastric mucosal lesions are an inevitable complication in patients with liver cirrhosis. Their etiology, however, is as yet unknown. The present study investigated phospholipid metabolism in the gastric mucosa of rats with cirrhosis induced by carbon tetrachloride. Gastric mucosal lesions were induced by taurocholic acid (TCA) which was given through a gastric tube. Levels of phospholipids, phosphatidylcholine, and disaturated-phosphatidylcholine were found to be markedly reduced at the mucosal surface in the cirrhotic rats, and they were increased in the gastric juice. Metabolism of phospholipids in the gastric mucosa was visualized by³H-choline autoradiography and the rate of phospholipid metabolism was found to be reduced. These results strongly suggest that mucosal lesions induced by bile regurgitation into the stomach are due to disturbance of phospholipid metabolism in the gastric mucosa.     

Simultaneous double-isotope autoradiographic measurement of local cerebral glucose metabolic rate and acid-base status in rat brain

We developed a double-isotope autoradiographic method for the simultaneous measurement of the local cerebral metabolic rate for glucose (1CMRG) and index of regional acid-base status (rABI) in single brain slices using [2-¹⁴C]deoxy-D-glucose (DG) and 5,5-dimethyl-[2-¹⁴C]oxazolidine-2,4, dione (DMO). After iv isotope administration, paper chromatography separates plasma DMO from DG activity using a methanol-methylene chloride solvent system. Initial tissue autoradiograms depict regional DMO plus DG and DG metabolite distribution. After 14 days in a well-ventilated hood, 97.5 ±0.5% of all DMO is lost from tissue sections by sublimation, and a second autoradiogram depicts DG plus DG metabolite distribution. Retention of brain lipids does not alter beta-particle self-absorption, avoiding problems associated with isotope extraction with solvents. Autoradiograms are digitized and converted to isotope-content images. The second autoradiogram is used for lCMRG computation. After subtracting the second regional isotope-content value from the first, the DMO content is obtained and used to compute rABI. Application of this method to normal animals yields expected values for lCMRG and rABI. This method is amenable to whole-slice digitization and creation of functional images of lCMRG and ABI followed by pixel-by-pixel correlations of the two variables, making this a potentially valuable tool for the investigation of the relationships between glucose metabolism and brain acid-base balance.     

On the accumulation of alloxan in the pancreatic β-cells

Summary Autoradiographic studies revealed that the radioactivity in the pancreatic islets was higher than in any other mouse tissue after intravenous injections of tracer doses of ¹⁴C-2-alloxan. The concentration of radioactivity in the endocrine pancreas concerned a great majority of the cells indicating that at least cells were involved. The uptake of the radioisotope in the pancreatic islets was considerably reduced when the small amounts of ¹⁴C-2-alloxan were complemented with carrier to bring up the total dose to the diabetogenic level or were proceeded by higher doses of non-radioactive alloxan. There was no accumulation of radioactivity in the islets after injection of the non-diabetogenic conversion products of ¹⁴C-2-alloxan obtained in an alkaline medium and only insignificant uptake was noted after exposure of the radioactive alloxan to the reactive SH-groups of glutathione. The absence of significant radioactivity in the islets of growing animals after tracer doses of ¹⁴C-2-alloxan suggests that the ability of the cells to concentrate alloxan is confined to the adult age.This study was supported by grants from the Swedish Medical Research Council, the United States Public Health Service (AM-05759-05) and Knut and Alice Wallenbergs Stiftelse.     

Impacted morsellized bone grafting and cemented primary total hip arthroplasty for acetabular protrusion in patients with rheumatoid arthritis: An 8- to 18-year follow-up study of 36 hips

Between 1979 and 1989, we performed 36 primary total hip replacements in 31 rheumatoid arthritis patients with protrusio acetabuli. The deficient acetabulum was reconstructed with autologous morsellized bone grafts from the femoral head. 3 patients were lost to follow-up. 12 patients (13 hips) died within 8 years postoperatively, none had a revision. 16 patients (20 hips) were reviewed at an average follow-up of 12 (8-18) years. In 2 hips, a revision was performed for aseptic loosening of the acetabular component, 6.5 and 8 years after primary surgery, which means a 90% (95% CI: 77%-100%) survival rate at 12 years (Kaplan Meier analysis). This technique is a good option in cases with protrusio acetabuli due to rheumatoid arthritis.     

Double-tracer autoradiographic study of protein synthesis and glucose consumption in rats with focal cerebral ischemia

Abstract

A double-tracer autoradiographic method for simultaneous measurement of regional glucose utilization (rCMR_glc) and regional protein synthesis (PS) in consecutive brain sections is described and applied to study the metabolism of the ischemic penumbra 2 h after occlusion of the middle cerebral artery (MCAO) in rats. In halothane anesthesia, the left middle cerebral artery was permanently occluded. Two hours after MCAO an i.v. bolus injection of ¹⁴C-deoxyglucose and ³H-leucine was given and circulated for 45 min. Two sets of brain sections were processed for quantitative autoradiography. Neighboring brain sections exposed an X-ray film (3 H-insensitive), and a ³H-sensitive for determination of rCMR_glc and PS, respectively. Sections for PS determination were washed in trichloroacetic acid (TCA) prior to film exposure in order to remove ¹⁴C-deoxyglucose and unincorporated ³H-leucine. Regional rates of PS and glucose utilization were measured by densitometric image analysis. Normal rates of metabolism were defined as mean ± 2 SD of values in the non-ischemic cortex. The volumes of ischemic cortex displaying normal rates of PS and glucose utilization, respectively, were measured. The cortical volume with normal PS was significantly less than that of normal rCMR_glc: 142 (127-147) mm³ vs. 203 (184-206) mm³. Treatment with the glutamate antagonists MK-801 (1 mgkg^–1) and NBQX (30 mg kg^–1 x 2) did not significantly change this, although MK-801 tended to reduce the size of the metabolic penumbra calculated as the difference between ischemic cortex with reduced PS and ischemic cortex with reduced rCMReic. [Neurol Res 1991; 21: 687–694]     

Status epilepticus causes a long-lasting redistribution of hippocampal cannabinoid type 1 receptor expression and function in the rat pilocarpine model of acquired epilepsy

Activation of the cannabinoid type 1 (CB1) receptor, a major G-protein-coupled receptor in brain, acts to regulate neuronal excitability and has been shown to mediate the anticonvulsant effects of cannabinoids in several animal models of seizure, including the rat pilocarpine model of acquired epilepsy. However, the long-term effects of status epilepticus on the expression and function of the CB1 receptor have not been described. Therefore, this study was initiated to evaluate the effect of status epilepticus on CB1 receptor expression, binding, and G-protein activation in the rat pilocarpine model of acquired epilepsy. Using immunohistochemistry, we demonstrated that status epilepticus causes a unique "redistribution" of hippocampal CB1 receptors, consisting of specific decreases in CB1 immunoreactivity in the dense pyramidal cell layer neuropil and dentate gyrus inner molecular layer, and increases in staining in the CA1-3 strata oriens and radiatum. In addition, this study demonstrates that the redistribution of CB1 receptor expression results in corresponding functional changes in CB1 receptor binding and G-protein activation using [3H] R+-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazin-yl](1-napthalen-yl)methanone mesylate (WIN55,212-2) and agonist-stimulated [35S]GTPgammaS autoradiography, respectively. The redistribution of CB1 receptor-mediated [35S]GTPgammaS binding was 1) attributed to an altered maximal effect (Emax) of WIN55,212-2 to stimulate [35S]GTPgammaS binding, 2) reversed by the CB1 receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride (SR141716A), 3) confirmed by the use of other CB1 receptor agonists, and 4) not reproduced in other G-protein-coupled receptor systems examined. These results demonstrate that status epilepticus causes a unique and selective reorganization of the CB1 receptor system that persists as a permanent hippocampal neuronal plasticity change associated with the development of acquired epilepsy.     

Regional brain imaging of vesicular acetylcholine transporter using o‐[125I]iodo‐trans‐decalinvesamicol as a new potential imaging probe

In this study, the regional rat brain distribution of radioiodinated o‐iodo‐trans‐decalinvesamicol ([¹²⁵I]OIDV) was determined in vivo to evaluate its potential as a single‐photon emission computed tomography (SPECT) imaging probe for vesicular acetylcholine transporter (VAChT). Following intravenous injection, [¹²⁵I]OIDV passed freely across the blood–brain barrier and accumulated in rat brain. The accumulation of [¹²⁵I]OIDV in rat brain was significantly reduced by coadministration of (+/?)‐vesamicol (0.125 µmol). In contrast, the coadministration of σ‐receptor ligands, such as (+)‐pentazocine (0.125 µmol) as a σ‐1 receptor ligand and (+)?3‐(3‐hydroxyphenyl)‐N‐propylpiperidine (0.125 µmol) as a σ‐1 and σ‐2 receptor ligands, barely affected the accumulation of [¹²⁵I]OIDV in rat brain. These findings in vivo were corroborated by autoradiographic analysis ex vivo. The authors found that the tracer binds with pharmacological selectivity to VAChT in rat brain and predicted that it may likewise serve in translational SPECT imaging studies of this marker in the integrity of cholinergic innervations. Synapse 68:107–113, 2014. © 2013 Wiley Periodicals, Inc.     

Minimal contribution of P-gp on the low brain distribution of naldemedine,a peripherally acting μ-opioid receptor antagonist

Naldemedine tosylate, a peripherally acting μ-opioid receptor antagonist, is indicated for treatment of opioid induced constipation in both Japan and US. Naldemedine has limited ability to affect the central analgesic effect of opioid analgesics. In this study, we investigated the contribution of P-glycoprotein (P-gp) on the brain distribution of naldemedine. Naldemedine tosylate showed acceptable oral absorption in rats. Following a single oral administration of [¹⁴C]-naldemedine tosylate to rats and ferrets, little radioactivity was detected in the region protected by the blood-brain barrier (BBB). In the assessment using Caco-2 cells, it was determined that naldemedine is a substrate for P-gp. The contribution of P-gp to the brain distribution of naldemedine was assessed using multidrug resistance 1a/b (mdr1a/b) knockout mice. While the brain-to-plasma concentration ratio (brain Kp) of naldemedine in the mdr1a/b knockout mice was 4-fold of that in the wild-type mice, the brain Kp in the mdr1a/b knockout mice was quite low (brain Kp < 0.1). These results suggest that the low brain distribution of naldemedine was due to the limited ability to cross the BBB rather than efflux by P-gp and therefore brain distribution of naldemedine would not be affected by concomitant administration of P-gp inhibitors or functional disorder of P-gp.     

Evaluation of [18F]2FP3 in pigs and non‐human primates

So far, no suitable 5‐HT₇R radioligand exists for clinical positron emission tomography (PET) imaging. [¹⁸F]2FP3 was first tested in vivo in cats, and the results were promising for further evaluations. Here, we evaluate the radioligand in pigs and non‐human primates (NHPs). Furthermore, we investigate species differences in 5‐HT₇R binding with [³H]SB‐269970 autoradiography in post‐mortem pig, NHP, and human brain tissue. Specific binding of [¹⁸F]2FP3 was investigated by intravenous administration of the 5‐HT₇R specific antagonist SB‐269970. [³H]SB‐269970 autoradiography was performed as previously described. [¹⁸F]2FP3 was synthesized in an overall yield of 35% to 45%. High brain uptake of the tracer was found in both pigs and NHPs; however, pretreatment with SB‐269970 only resulted in decreased binding of 20% in the thalamus, a 5‐HT₇R–rich region. Autoradiography on post‐mortem pig, NHP, and human tissues revealed that specific binding of [³H]SB‐269970 was comparable in the thalamus of pig and NHP. Despite the high uptake of [¹⁸F]2FP3 in both species, the binding could only be blocked to a limited degree with the 5‐HT₇R antagonists. We speculate that the affinity of the radioligand is too low for imaging the 5‐HT₇Rs in vivo and that part of the PET signal arises from targets other than the 5‐HT₇R.     

Targeting of Teniposide to the Mononuclear Phagocytic System (MPS) by Incorporation in Liposomes and Submicron Lipid Particles; An Autoradiographic Study in Mice

Liposomes are concentrated in the mononuclear phagocytic system in vivo and may therefore be of value as carriers of drugs when treating diseases involving phagocytic cells. Teniposide (VM-26) is a potent and lipophilic cytotoxic drug. Teniposide was incorporated in large unilamellar liposomes (LUVs) consisting of egg phosphatidylcholine and dioleoyl phosphatidic acid and into the novel submicron lipid particles containing cholesteryl oleate, cholesteryl palmitate and soybean lecithin, in order to evaluate the drug targeting effect. Radiolabelled teniposide and lipids were used and the organ distribution in mice was studied with whole-body autoradiography 20 and 90 min post i.v. injection. When the commercial formulation of teniposide (Vumon) was administered, teniposide accumulated in the liver where the drug is metabolized. Biliary excretion was rapid and considerable already after 20 min. The liposomal formulation enhanced liver uptake of teniposide slightly. The distribution of radiolabelled phosphatidyl choline differed from that of teniposide indicating instability of the liposomes in circulation. Despite this, the splenic uptake of the drug was significantly enhanced by administration in liposomes. In the red pulp of the spleen the teniposide level was 23 times higher 90 min post injection, using the liposomal formulation as compared to free drug. The submicron lipid particles were mainly accumulated in the liver and to a lesser extent in the spleen. The study shows that liposomes and lipid particles enhance splenic and liver uptake and can be used to target teniposide to the MPS.