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Biomedical subjects

C Larsson

Publications and source records attributed to C Larsson.

At least 343 records · Page 19Linked to original sources
PubMed1987

Memory disorders as a function of traumatic brain injury. Word completion, recall of words and actions.

The memory performance of a group with traumatic brain injury and a matched control group was assessed using the following methods (a) word completion, (b) immediate free, final free and final cued recall of words and (c) immediate free and final free recall of subject-performed tasks (SPTs) and SPTs without motor action (SPTs-WA). The brain-injured (BI) group was significantly inferior relative to the control group in all recall tests except immediate free recall of words. No difference was revealed in the word completion test. The BI-group benefitted less by cues presented either at retrieval (final cued recall of words) or at the time of encoding already built-in in the stimulus (SPTs and SPTs-WA). The results were discussed in terms of the neuropathological background of the patients in the BI-group suggesting that frontal dysfunction could play a critical role. When comparing the tests within the BI-group, however, the performance was better when cues were present and especially so for long-term memory. Motor activity also facilitated long-term memory. Finally, an attempt was made to specify conditions for guidance in the construction of training programmes.

Adult↗
PubMed1986

Fractionation of rat liver plasma-membrane regions by two-phase partitioning.

Rat liver plasma membranes, enriched in blood-sinusoidal or bile-canalicular regions by differential and sucrose-gradient centrifugation, were further purified by partitioning in an aqueous polymer two-phase system. This method separates membranes according to differences in surface properties rather than size and density. A several-fold increase in the ratio of leucine aminopeptidase (a bile-canalicular marker) and 5'-nucleotidase to asialo-orosomucoid binding (a blood-sinusoidal marker) was obtained in one fraction, whereas another fraction gave a 2-3-fold increase in ratio of blood-sinusoidal to bile-canalicular markers. Furthermore, the markers for both regions of the plasma membrane, as well as markers for Golgi membranes and lysosomes, showed a heterogeneous behaviour on counter-current distribution.

Animals↗
PubMed1986

Subchronic treatment of rats with nicotine: effects on tolerance and on [3H]acetylcholine and [3H]nicotine binding in the brain.

The effects of subchronic nicotine treatment on the development of tolerance and on two nicotinic ligand binding sites were investigated. After subcutaneous injection of nicotine (0.45 mg nicotine base/kg) or saline twice a day for 14 days the body weight of rats was significantly lower than that of control animals. A significant tolerance to the acute effects of nicotine on locomotor activity and body temperature was observed after the treatment period. Nicotine treatment also resulted in a significant increase in [3H]acetylcholine (3H-ACh) binding in the midbrain (48.3% increase in comparison with controls) and hippocampus (38.3% increase), whereas the binding of [3H]nicotine (3H-NIC) was unaffected in all brain areas investigated. These results indicate that subchronic s.c. injections of nicotine can differentially affect the binding of two different nicotinic ligands in the brain. It is also concluded that the development of tolerance to the acute effects of nicotine on locomotor activity and temperature is not directly dependent upon changes in binding of [3H]nicotine to the brain.

Acetylcholine↗
PubMed1985

Effect of long-term nicotine treatment on [3H]nicotine binding sites in the rats brain.

Male rats were receiving nicotine (base), 50 mg/kg in their drinking fluid for 9 and 41 weeks, respectively. A markedly reduced intake of fluid was observed during both regimes of nicotine treatment. At withdrawal of nicotine after 9 weeks of treatment the intake of water was immediately increased up to control level while in rats with 41 weeks of exposure the intake of drinking fluid increased to 65% over the control level still 14 days after withdrawal of nicotine. Tolerance to nicotine was measured after 7 days of abstinence in rats treated for 9 weeks. No significant change in cholineacetyltransferase (ChAT) activity or number of muscarinic binding sites in brain was observed after 9 or 41 weeks of nicotine treatment. Twenty-four hours after withdrawal from the 41 weeks nicotine treatment there was a significant increase of 46% in the number of [3H] nicotine binding sites in the hippocampus while the number of binding sites was decreased by 44% in the cortex and unchanged in the midbrain. On day 14th of abstinence these changes had disappeared. Following 9 weeks of nicotine treatment no change in [3H] nicotine binding was observed after 24 h or 7 days of abstinence.

Animals↗
PubMed1985

Surface properties of right side-out plasma membrane vesicles isolated from barley roots and leaves.

Highly purified plasma membrane vesicles were obtained from roots and leaves of 7-day-old light-grown barley (Hordeum vulgare L. cv Kristina) seedlings by partitioning of crude microsomal fractions in a dextran-polyethylene glycol two-phase system. Sodium dodecylsulfate polyacrylamide gel electrophoresis showed the polypeptide composition of plasma membranes from the two organs to be qualitatively similar, but with different relative amounts of some of the polypeptides. Between 80 and 100% of the K(+),Mg(2+)-ATPase activity was latent indicating that the vesicles were sealed and right side-out. The isoelectric points of the outer surface of root and leaf plasma membranes as determined by cross-partitioning were similar and quite acidic-about pH 3.6. In contrast, the net negative surface charge density at pH 7.0 as measured by 9-aminoacridine fluorescence differed significantly, being -29 mC.m(-2) for the leaf plasma membrane and only -19 mC.m(-2) for the root plasma membrane. As isolated, both types of plasma membrane vesicles had Ca(2+) and Mg(2+) bound to the outer surface as shown by the combined use of chelators and 9-aminoacridine fluorescence; however, the leaf plasma membrane had a relatively higher proportion of Ca(2+) bound (0.57) than did the root plasma membrane (0.45). This difference probably reflects differences in the in vivo conditions as no chelator was present during the isolation procedure. Also Ni(2+) could bind to the root vesicles as indicated by the effect of Ni(2+) on 9-aminoacridine fluorescence, and by the binding of (63)Ni(2+) (44 nanomoles bound per milligram protein) at 100 micromolar NiCl(2).

Journal Article↗
PubMed1985

Comparative analysis of nicotine-like receptor-ligand interactions in rodent brain homogenate.

The effects of different variables such as incubation time, temperature, tissue protein content, and pH on the interactions of various labelled nicotinic ligands with nicotine-like binding sites in vitro were studied in rodent brain preparations. The ligands tested were alpha-[3H]bungarotoxin (alpha-[3H]BTX), [3H]tubocurarine ([3H]TC), and [3H]nicotine ([3H]NIC). The regional distribution of the labelled nicotinic ligand binding was also studied and affinity constants and maximal binding (Bmax) values for the equilibrium [3H]NIC binding are given. Association kinetics for [3H]NIC and [3H]TC binding to brain homogenate were similar, with maximal binding within 5-10 min of incubation, followed by a continuous decrease. In contrast, the binding of alpha-[3H]BTX to brain homogenate was much slower, reaching equilibrium after 30-60 min of incubation. Scatchard analysis of equilibrium binding data for [3H]NIC in the hippocampus indicated two binding sites: a high-affinity site (Bmax, 60 pmol/g protein; KD, 6 nM) and a low-affinity site (Bmax, 230 pmol/g protein; KD, 125 nM). The data for the high-affinity [3H]NIC binding site are very similar to previously found data for the high-affinity binding site of [3H]TC and the binding site of alpha-[3H]BTX. Each ligand showed regional differences in binding, and the binding pattern also differed between the ligands.

Animals↗
PubMed1984

Hypothermia and infection in Wernicke's encephalopathy.

Two cases of acute Wernicke's encephalopathy with severe hypothermia as the major presenting feature are reported. Treatment with thiamine was rapidly introduced, but hypothermia nevertheless persisted for several weeks, at times masked by intercurrent infections.

Aged↗
PubMed1983

Muscarinic receptor compensation in hippocampus of Alzheimer patients.

The activity of the acetylcholine synthesizing enzyme choline acetyltransferase (ChAT) (presynaptic marker) and number of muscarine-like receptor binding sites have been measured in the hippocampus from eight individuals with senile dementia of Alzheimer type (SDAT) and ten controls. A negative correlation (r = 0.80; p less than 0.05) was found between the ChAT activity and the number of muscarine-like receptors in the SDAT group but not in the controls. The findings might indicate an ongoing compensatory receptor mechanism as a response to changes in presynaptic cholinergic activity.

Aged↗
PubMed1983

Changes in cholinergic activity in human hippocampus following chronic alcohol abuse.

Cholinergic mechanisms in the hippocampus seem to play a role in memory function. Since it is well known that chronic alcoholics often have a disturbed memory function, the cholinergic activity of the hippocampus has been measured in 20 chronic alcoholics and 14 controls, post-mortem. Of the alcoholics, 13 were classified as "intoxicated" alcoholics and 7 as "sober" alcoholics, i.e., without ethanol in blood or urine at the time of death. A lower, although not significantly lower activity of the enzyme choline acetyltransferase (ChAT, presynaptic marker) was measured in the hippocampus of the chronic alcoholics as compared to the control group. A trend towards a lower number of muscarine-like binding sites was also observed for the alcoholic group, but was only significant for the oldest group of alcoholics (59-68 years; -30%; p less than 0.01) in comparison to controls. No significant change in the number of nicotine-like binding sites was found. A normal aging process with degenerative nerve cell changes might, in combination with an excessive intake of ethanol, lead to the more pronounced decrease in muscarine-like binding sites found for the older alcoholics.

Aged↗
PubMed1982

Interactive computer program for self-distributed medical questionnaire in a population health screening.

The questionnaire is an important element of a medical screening investigation, just as important as the biometrical screening tests. There are several difficulties in realizing interactive computer programs for such tasks. In the present report, we describe the design, operation and results of an interactive computer program for self-distributed medical questionnaire in which the screening subjects are informed and instructed on the terminal routines, and answer, check, confirm and record the questions direct in the computer terminals by means of simple keyboard functions. This program was possible to construct as an integrated component of the interactive computer system monitoring our multiphasic health screening in a standard minicomputer environment.

Computers↗
PubMed1982

Experiences with an interactive computer program for recording biometrical health screening data.

The nurses' measurements of biometrical health screening data comprise the central elements in our multiphasic preventive medical investigation in Malmö. It is also vitally important for the information processing, evaluation and actions of the screening that all test values and other data can be supplied to a uniform computer bank without delay in terms of secondary transferral routines. In our ongoing population investigation projectin Malmö, this has been accomplished by on-line computer programs for the different components of the screening. Here we describe the practical experiences with the subroutine use by the nurses to feed the biometrical test results to the computer bank.

Biometry↗
PubMed1982

Cholinergic activity in hippocampus in chronic alcoholism.

Evidence indicates that hippocampus and cholinergic mechanisms play a role in memory function. Animal studies have indicated an effect of prolonged ethanol treatment on cholinergic parameters. It is well known that chronic alcoholics often have a disturbed memory function. In this postmortem study the cholinergic activity in the hippocampus was studied in 20 chronic alcoholics and 14 controls. Of the alcoholics, 13 were classified as 'intoxicated alcoholics' and 7 as 'sober alcoholics', i.e., without ethanol in blood and urine at the time of death. To study both pre- and postsynaptic effects, the enzyme choline acetyltransferase (ChAT, presynaptic marker) as well as muscarine- and nicotine-like receptor binding sites were measured. There was a lower, although not significant, activity in ChAT in the hippocampus of the chronic alcoholics as compared to the controls. The lowest ChAT activity was found in the group of 'sober alcoholics', however it was not statistically significant. In the chronic alcoholics there was a trend towards lower numbers of muscarine-like binding sites reaching significance for the oldest group of alcoholics (59 - 68 years; -30%; p less than 0.01) in comparison to controls. The combination of the normal aging process with degenerative nerve cell changes and alcohol abuse might lead to the more pronounced decrease in muscarinic binding sites found for the older alcoholics.

Adult↗
PubMed1982

Plasma membranes from oats prepared by partition in an aqueous polymer two-phase system : on the use of light-induced cytochrome B reduction as a marker for the plasma membrane.

Presumptive plasma membrane fractions have been prepared from oat (Avena sativa L. cv. Brighton) roots and shoots, respectively, by partition of microsomal fractions in a dextran-polyethylene glycol two-phase system. The plasma membranes had a high affinity for the polyethylene glycol-rich upper phase, whereas membranes from mitochondria and other organelles partitioned in the dextran-rich lower phase or at the interface. Thus, relatively pure plasma membranes were obtained by only two partition steps, and within 3 hours from homogenization of the material.The plasma membranes from both organs were enriched in K(+)-stimulated Mg(2+)-dependent ATPase and glucan synthetase II, two tentative markers for the plant plasma membrane. Silicotungstic acid, an indicative stain for the plasma membrane, stained the vesicles recovered from the upper phase, but failed to stain the membranes partitioning in the lower phase or at the interface.The plasma membranes were also enriched in a light-reducible b-cytochrome. This b-cytochrome can be measured by its light-induced absorbance change and may serve as a marker for the plant plasma membrane.

Journal Article↗
PubMed1982

A hypokalemic index ECG as a predictor of hypokalemia.

ECGs of 36 hypokalemic patients (K/s 1.0-3.5 mM/l) were analysed. The sum of the S-T depression and the U wave amplitude in leads II and V3 was used and constituted the uncorrected hypokalemic index. To correct the hypokalemic index, the figure obtained during normokalemia is subtracted from that obtained during hypokalemia. The corrected hypokalemic index gives an approximation of the K/s irrespective of other factors permanently influencing the ECG, such as treatment with antiarrhythmic drugs, coronary insufficiency, and ventricular hypertrophy. The corrected index was greater than 4.0 at a K/s of less than 2.0 mM/l. Eight out of nine patients with a K/s 2.1-2.6 had an index of 1.5-3.5. All patients with a K/s greater than 2.6 mM/l had an index less than 1.5.

Digitalis Glycosides↗
PubMed1981

Highly purified mitochondria from rat brain prepared by phase partition.

Mitochondria and synaptosomes from adult rat forebrain can easily be separated by counter-current distribution in an aqueous two phase system composed of Dextran T500 and poly(ethylene glycol) 4000. Both particles may also be separated by a batch procedure in which the same phase system is used. Electron micrographs and enzymatic activities show a high purity of the mitochondria obtained from the dextran-rich lower phase. Electron micrographs and enzymatic activities also show that intact synaptosomes can be obtained from the poly(ethylene glycol)-rich upper phase. The mitochondria purified by this method show good ADP/O ratios, respiratory control ratios, and state 3 rates. Synaptosomes showed a state 2-state 3 transition with no recuperation to state 4.

Acetylcholinesterase↗