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Biomedical subjects

C Zimmermann

Publications and source records attributed to C Zimmermann.

At least 19 recordsLinked to original sources
PubMed1991

[Behçet's syndrome. Possible differential diagnosis in multi-system symptoms].

Behçet's syndrome was described as a triad with recurrent ulcers of the mouth, aphthae of the genitals as well as changes of the eyes. A fourth later added main criterion comprises multifarious dermatological symptoms. Facultative signs of a disease, which, however, occasionally may stand also in the centre of the clinical picture are vascular, gastrointestinal and central-nervous participations, arthritic pains and swellings as well as an epididymitis. On account of the infrequency of the disease outside the endemic regions and the development of the individual manifestations over larger periods it is often recognized very late. Out of the six casuistics described three of them fulfilled the criteria of a complete Behçet's syndrome with evidence of all four main criteria, in the remaining casuistics the incomplete clinical picture was present with three main and one to four side criteria. In all cases the course was relatively benign. Recently, streptococcal antigens were considered to be etiological factors; correlations with the HLA-system are ascertained for patients from endemic regions. In phases of clinical activity the combination of immunosuppressive agents with cortisonoids is the therapy of choice.

Adult↗
PubMed1990

Increased serotoninergic and noradrenergic activity in hepatic encephalopathy in rats with thioacetamide-induced acute liver failure.

Functional changes of various neurotransmitter systems have been implicated in the pathogenesis of hepatic encephalopathy. In this study the role of brain monoaminergic neurotransmitter systems in hepatic encephalopathy was investigated in rats with thioacetamide-induced acute liver failure. Concentrations of serotonin, dopamine, noradrenaline and of their metabolites 5-hydroxyindoleacetic acid, dihydroxyphenylalanine (following inhibition of dihydroxyphenylalanine-decarboxylase), dihydroxyphenylacetic acid, homovanillic acid and 3-methoxy-4-hydroxyphenyl-glycol, were measured in the cerebral cortex, striatum and hippocampus by high performance liquid chromatography with electrochemical detection. In hepatic encephalopathy concentrations of 5-hydroxyindoleacetic acid were increased in all three brain areas (196%, 204% and 264% of saline-treated controls, p less than 0.01), and concentrations of serotonin were increased in the frontal cortex (121%, p less than 0.01). In the frontal cortex and hippocampus of encephalopathic rats dopamine levels were increased (157% and 289%, p less than 0.05), and levels of noradrenaline (53% and 46%, p less than 0.05) were decreased associated with increased 3-methoxy-4-hydroxyphenylglycol levels (173% and 206%, p less than 0.05). The extent of these changes correlated with the stage of hepatic encephalopathy. In hepatic encephalopathy dihydroxyphenylalanine accumulation was increased in the hippocampus and unchanged in the cerebral cortex. Dopamine, noradrenaline, dihydroxyphenylacetic acid and homovanillic acid concentrations were unchanged in the striatum. The results of this study indicate that hepatic encephalopathy in thioacetamide-induced acute liver failure in rats is associated with neurochemical changes, suggesting an increased activity of the noradrenergic and serotoninergic neurotransmitter systems.

Amino Acids↗
PubMed1990

Renal effects of administered atrial natriuretic peptide in the conscious, aging rat.

Studies were performed in conscious, chronically catheterized male Sprague-Dawley rats to investigate the effect of administered atrial natriuretic peptide (ANP) on blood pressure, renal hemodynamics and urinary electrolyte excretion. Studies were performed on young adult (3-4 month old) rats and on aging rats (18-24 months of age). Low dose ANP (80 ng/kg/min for 60 min) had no effects on renal hemodynamics in either young or old rats and produced only a slight blood pressure reduction in young animals. No effect on urinary electrolyte excretion was evident in young rats whereas in the old animals, low dose ANP produced large rises in the rate of sodium excretion, fractional excretion of sodium and urine flow rate. A four fold higher dose of ANP evoked a moderate natriuretic and a marked antihypertensive response in young rats. Time control studies indicated that time alone had no influence on urinary sodium excretion rate, the fractional excretion of sodium or urine flow rate. These studies indicate a much enhanced sensitivity to the natriuretic effects of administered ANP by the kidneys of old rats.

Aging↗
PubMed1990

Urinary excretion patterns of endogenously produced alcohols in type 1 (IDDM) and type 2 (NIDDM) diabetes mellitus compared with healthy control subjects.

Urinary excretion patterns of various endogenously produced alcohols, such as ethanol, propanol, isobutanol, butanol, and isopentanol, were evaluated in 17 type 1 (IDDM) and 15 type 2 (NIDDM) diabetic patients, and in two different groups of healthy control subjects (n = 12, n = 8, respectively) matched for sex, age and weight. In addition to the urinary alcohol excretion determined by gas-chromatography and mass-spectrometry, four cardiovascular reflex tests were performed, and the motor and sensory conduction velocities of three different peripheral nerves were measured. In the type 1 diabetic patients, urinary excretions of ethanol and propanol were significantly higher than in the control subjects (P less than 0.0001, P less than 0.00001, respectively), whereas the control subjects exhibited significantly higher urinary excretion rates of the other three alcohols (P less than 0.007, P less than 0.02 and P less than 0.002, respectively) compared with the type 1 diabetic patients. In the type 2 diabetic patients, only the urinary excretion of propanol was significantly elevated (P less than 0.002) compared with the control subjects, while the urinary excretion rates of butanol and isopentanol were significantly lower (P less than 0.02, P less than 0.05, respectively) than in the controls. Urinary alcohol excretions were not related to diabetic peripheral neuropathy in both groups studied. The clinical meaning of the urinary excretion patterns of different endogenously produced alcohols in diabetes mellitus has to be further evaluated.

Adult↗
PubMed1990

Delayed endolymphatic hydrops and its relationship to Meniére's disease.

Delayed endolymphatic hydrops (EH) can be characterized as having ipsilateral and contralateral types. They are similar in that both have early and late phases of otologic symptoms and that the early phase is a profound hearing loss in one ear. The late phases differ, however, in that the ipsilateral type develops the symptoms of EH (episodic vertigo) in the deaf ear and the contralateral type develops the symptoms of EH (fluctuating hearing loss and/or episodic vertigo) in the hearing ear. In more than half the cases of both types of delayed EH, the profound hearing losses in the early phase are simply discovered to be present in early childhood without a known time of onset. The temporal bones of two patients with contralateral delayed EH show pathologic changes in the deaf ears that are similar to those known to occur in mumps and measles labyrinthitis, whereas the pathologic changes in the hearing ears are similar to those known to occur in Meniere's disease. These observations support the proposition that Meniere's disease may occur as a delayed sequela of inner ear damage sustained during an attack of subclinical viral labyrinthitis occurring in childhood.

Adolescent↗
PubMed1989

Hepatic encephalopathy in thioacetamide-induced acute liver failure in rats: characterization of an improved model and study of amino acid-ergic neurotransmission.

An imbalance of excitatory and inhibitory amino acid-ergic neurotransmission has been suggested to play a role in the pathogenesis of hepatic encephalopathy. For further evaluation of this hypothesis, several parameters of amino acid-ergic neurotransmission were studied in rats with acute liver failure induced by the administration of 300 mg per kg thioacetamide by gavage on two consecutive days. By appropriate supportive care, hypoglycemia, renal failure and hypothermia were avoided. Rats were monitored clinically and neurologically. Hepatic encephalopathy evolved in four distinct, easily recognizable stages. Light and electron microscopic examination of brains of rats with hepatic encephalopathy revealed only a slight swelling of nuclei of neurons and astrocytes without signs of neuronal degeneration or brain edema. In rats with hepatic encephalopathy, the concentrations of GABA, glutamate and taurine were decreased in the cerebral cortex, the hippocampus and the striatum, whereas those of aspartate and glycine were unchanged or increased. GABAA and benzodiazepine receptors were studied as parameters for the postsynaptic GABAA-benzodiazepine receptor complex, glutamic acid decarboxylase as parameter for presynaptic GABA-ergic neurons and stimulation of benzodiazepine binding by GABA as a parameter for a GABA-mediated postsynaptic event. None of these parameters was different in hepatic encephalopathy as compared to controls. Similarly, Ca++/Cl(-)-dependent and -independent glutamate receptors as parameters for glutamatergic neurons were unchanged in rats with hepatic encephalopathy. Thus, in rats with thioacetamide-induced liver failure and hepatic encephalopathy, changes of the concentrations of neurotransmitter amino acids occur in the brain. Other neurochemical parameters, however, failed to identify alterations of GABA-ergic or glutamatergic neurotransmission in hepatic encephalopathy.

Acetamides↗
PubMed1989

Cerebral glutamine metabolism: study of modulatory effects of glutamine on gamma-aminobutyric acid-ergic neurotransmission.

Glutamine is one major precursor of gamma-aminobutyric acid (GABA) and glutamate, the most important inhibitory and excitatory neurotransmitters in the mammalian brain, respectively. Changes in cerebral glutamine concentrations occur in various metabolic encephalopathies including hyperammonemia and liver failure. As glutamine inhibits the specific binding of GABA to its postsynaptic receptor at physiologic concentrations, in this study the effects of glutamine on various components of the GABAA-benzodiazepine receptor complex were studied. Glutamine dose dependently inhibited the stimulation of flunitrazepam binding by GABA. This inhibition occurred already at concentrations of 10 mumol/L glutamine. Glutamine had no effects on basal or GABA-stimulated synaptoneurosomal chloride uptake. It is concluded that glutamine is not a modulator of the GABAA-benzodiazepine neurotransmitter system. Thus, changes of cerebral glutamine concentrations are unlikely to contribute to the activation of GABA-ergic neurotransmission in liver failure.

Animals↗
PubMed1988

Mitochondrial myopathies with necrotizing encephalopathy of the Leigh type.

Two patients with mitochondrial encephalomyopathy (MEP) serve to emphasize the variability of this group of diseases. Cerebral insults, mitochondrial cardiopathy, relapsing ileus, cerebral angioma, ataxia, and myoclonic seizures characterized the first case of an adult man with similar diseases in his family, interpreted as transitional form between mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and myoclonus epilepsy associated with ragged red fibers (MERRF). The second patient, a floppy infant with cardiomyopathy and myoclonism, statomotoric and mental retardation showed combined defects in mitochondrial respiratory chain at NADH-CoQ reductase and cytochrome c oxidase and a deficiency of carnitine. In both patients neuropathologically criteria of Leigh's syndrome could be demonstrated in the cerebral cortex, in case 2 also clinically. The classificatory problems of the relationships between KSS, MELAS, MERRF, Leigh's as well as Alpers' syndromes are discussed.

Adult↗
PubMed1987

Postsynaptic gamma-aminobutyric acid receptors in hepatic coma following portacaval shunt and hepatic artery ligation in the rat.

The specific binding of gamma-aminobutyric acid (GABA) to synaptic membranes prepared from the brains of rats with acute liver failure due to portacaval shunt and hepatic artery ligation was measured. No changes in the affinity or the density of the low- and high-affinity binding sites of the GABA receptor were observed, indicating that this model of acute hepatic encephalopathy is apparently not associated with altered GABAergic neurotransmission.

Animals↗
PubMed1987

A benzodiazepine antagonist does not alter the course of hepatic encephalopathy or neural gamma-aminobutyric acid (GABA) binding.

The progressive course of hepatic encephalopathy developing in rats after massive hepatic ischemia due to hepatic artery ligation within 48 hr of a portacaval shunt was not altered by the injection of a benzodiazepine antagonist, CGS 8216, in a dose that was sufficient to reverse diazepam-induced coma quickly. The onset of hepatic coma was shortened 20 to 25% by the antagonist, rather than being delayed, as would be expected if hepatic coma were due to a gamma-aminobutyric acid (GABA)-ergic effect. The neural binding of GABA by brains from rats in deep hepatic coma was unaffected by the injection of the benzodiazepine antagonist.

Animals↗
PubMed1987

[Night work: a choice of society?].

The methodology and first results of a research on night-work management, carried out by the PNR 15, are presented. We show that the effects of night-work and the way it is experienced by the workers, varies from one person to another, and mainly depend on the type of activity concerned and on work conditions. With the aim of prevention, we try to define risk-populations.

Circadian Rhythm↗
PubMed1985

[Visual evoked potentials: methodologic problems--variations of stimulus parameters].

The evaluation of visual potentials (VEP) evoked by pattern reversal includes the latency and amplitude of P100. An increase in the mean brightness or contrast of the checkerboard stimulus results in an increase in amplitude and a decrease in latency of P100. A square edge subtense of 20' in checkerboard pattern or a spatial frequency of 3-4 cyc/degrees in stripe pattern produce maximum responses. Transient VEPs are recorded at low repetition rates (less than 2 Hz), steady state VEPs at temporal frequencies above 8 Hz. In the latter condition the VEP takes the character of a sinusoidal train of waves which, compared to transient stimulation allows for a better measurement of VEP amplitude. The latency of P100 increases with the age of the subject. The influence of the different stimulus parameters and recording techniques must be known and have to be kept constant in order to record reliable and reproducible VEPs.

Adolescent↗