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Biomedical subjects

H Schroeder

Publications and source records attributed to H Schroeder.

At least 73 records · Page 4Linked to original sources
PubMed1991

Influence of early chronic phenobarbital treatment on cerebral arteriovenous differences of glucose and ketone bodies in the developing rat.

The influence of an early chronic phenobarbital treatment on cerebral arteriovenous differences of glucose, lactate, pyruvate, beta-hydroxybutyrate and acetoacetate was studied in suckling rats. The animals were treated from day 2 to 21 after birth by a daily injection of 50 mg/kg phenobarbital or by saline and were studied at 10, 14 and 21 days. Phenobarbital treatment induced a decrease in cerebral arteriovenous difference of glucose at P14 and no change at P10 and P21. The barbiturate did not have any influence on cerebral arteriovenous difference of lactate and pyruvate at the three stages studied. Cerebral uptake of beta-hydroxybutyrate was unchanged at P10 and increased by two-fold at P14 and by threefold at P21 by phenobarbital. Cerebral arteriovenous difference of acetoacetate was low and did not change with the pharmacological treatment. At P14 and P21, the calculated amount of oxygen used by the brain for the oxidation of ketone bodies was twice as high in barbiturate- as in saline-treated rats and reached values of 47 and 16% respectively in phenobarbital-exposed animals. In addition, the barbiturate seemed to affect the carrier process of beta-hydroxybutyrate from blood to brain. The results of the present study are in good agreement with previous data from our laboratory showing that an early chronic phenobarbital treatment is able to induce a shift in the cerebral energy metabolism balance in favor of ketone bodies.

3-Hydroxybutyric Acid↗
PubMed1991

Causes and signs of temporomandibular joint pain and dysfunction: an electromyographical investigation.

The spontaneous muscular activity of the masseter and two non-masticatory muscles, and their activity under conditions of noise and flickering light, were recorded in 30 patients with mandibular dysfunction, and in 25 control subjects. The mood of the subjects during the investigation, and the possible presence of emotional disturbances was evaluated by means of questionnaires. The enhanced muscular activity of the masseter muscle differentiated patients from the control group, although it does not constitute a pathognomic sign. Unilaterality of complaints, and dysfunctions of differing intensity were not reflected in differential EMG findings. One-fifth of the patients exhibited neck muscle activity occurring simultaneously with the masseter activity. The effect of the applied stimuli on the muscular activity was not homogeneous, leading to activation in some cases and inhibition in others. Symptoms of anxiety could be observed in seven TMJ patients. Anxious patients showed higher levels of muscular activity and emotional irritability during the experiment than non-anxious patients.

Action Potentials↗
PubMed1991

Enhanced sensitivity of "metabotropic" glutamate receptors after induction of long-term potentiation in rat hippocampus.

Stimulation of [3H]inositol monophosphate ([3H]InsP) formation by ibotenate or trans-1-aminocyclopentyl-1,3-dicarboxylic acid (t-ACPD) in rat hippocampal slices was enhanced after tetanic stimulation of the Schaffer collaterals projecting to the CA1 region (in vitro) or the perforant pathway projecting to the dentate gyrus (in freely moving animals). This effect was observed 5 h (but not 2 h) after long-term potentiation (LTP) induction and was abolished if tetanic stimulation was performed in the presence of specific antagonists of N-methyl-D-aspartate receptors. The delayed increase in excitatory amino acid-induced polyphosphoinositide (PPI) hydrolysis was accompanied by an enhanced responsiveness to norepinephrine, whereas the basal and carbamylcholine-stimulated [3H]InsP formation were unchanged. These results suggest that an increased activity of "metabotropic" glutamate receptors may contribute to the synaptic mechanisms enabling the late expression and or maintenance of LTP. Accordingly, LTP decayed more rapidly (within 5 h) in rats repeatedly injected with LiCl (60-120 mg/kg, i.p., for 10 days), a treatment that led to a reduced efficacy of ibotenate and norepinephrine in stimulating PPI hydrolysis in hippocampal slices.

Animals↗
PubMed1991

High dose melphalan and total body irradiation with autologous marrow rescue in childhood acute lymphoblastic leukaemia after relapse.

High dose melphalan (HDM 110-140 mg/m2) and total body irradiation (TBI, 10.5 Gy, single fraction) followed by infusion of autologous bone marrow (ABMT) was evaluated for toxicity and efficacy in 24 children with acute lymphoblastic leukaemia (ALL) in second (CR2) or third remission (CR3). Marrow was purged with Campath 1 in six children (four were children in CR3). All children had engraftment with a median of 30 days (range 18-70 days) to neutrophil count greater than 0.5 x 10(9)/l. Four children (16%) died from toxicity 1-4 months after autograft, two from pneumonitis, one from an intracerebral haemorrhage and one from sepsis. Apart from fever and mucositis the procedure was well tolerated. Nine of 17 children treated in CR2 remain in complete remission 6-72 months after ABMT (median 25 months). Seven of these have a follow-up of greater than 12 months. Three of the seven children treated in CR3 are alive 17, 22 and 29 months post ABMT. Seven children relapsed within 10 months (median 4 months) of the autograft. Only one relapse has occurred beyond 10 months. HDM and TBI followed by ABMT is a relatively well tolerated regimen and may contribute to survival in children with relapsed ALL.

Adolescent↗
PubMed1990

Dopaminergic antagonists prevent long-term maintenance of posttetanic LTP in the CA1 region of rat hippocampal slices.

The involvement of dopaminergic mechanisms in the induction and maintenance of posttetanic long-term potentiation (LTP) was investigated on CA1 cells of rat hippocampal slices. The presence of the dopamine receptor blocker domperidone in a concentration of 1 microM during tetanization with 3 trains of 100 impulses (100 Hz) and a train interval of 10 min influences neither the synaptic transmission nor the induction of LTP. However, the potentiation of both the population spike and the population EPSP gradually decreases, thus significantly differing from control LTP about 4 h after initiation and reaching the level of non-tetanized controls about 7-8 h after tetanization. The simultaneous presence of 1 microM apomorphine during tetanization abolishes this effect of domperidone indicating the specific dopaminolytic nature of its action. Also the presence of the dopamine antagonists sulpiride and flupenthixol, respectively, in a concentration of 1 microM during tetanization likewise prevents the occurrence of the late LTP maintenance. The determination of [14C]dopamine in 2 min fractions from the superfused slices after preloading during a preincubation period revealed that a low frequency stimulation of the Schaffer collaterals with 0.33 Hz does not influence the spontaneous efflux of dopamine, whereas the tetanization with an impulse train of 100 Hz produces a significantly enhanced release. The observations suggest that dopaminergic influences during and immediately after tetanization at least additionally contribute to the induction of postsynaptic mechanisms subserving a late, long-lasting maintenance of potentiation. The results also support the assumed existence of different subsequent stages of LTP.

Animals↗
PubMed1990

Homeostatic disruption and memory: effect of insulin administration in rats.

The present study examined the effect of insulin-induced hypoglycemia on 24-h retention of passive avoidance in rats. In the initial experiment, rats received either insulin (50 U/kg) or saline injections 30 min prior to training and testing. Impairments in retention were observed when animals were trained with insulin and tested with saline. This anterograde memory loss was attenuated, however, when insulin was administered prior to both training and testing. A subsequent experiment further explored the disruptive effect of hypoglycemia on memory. Data from this study indicated that lower doses of insulin at training (5 and 10 U/rat) yielded impairments in 24-h retention of passive avoidance. It is concluded that disruption of glucoregulation can produce state-dependent anterograde memory losses in rats. Possible implications for the effects of hypoglycemia on cognitive functioning in humans are discussed.

Animals↗
PubMed1990

[Etiology of alveolitis and its therapy with indomethacin].

The local antiphlogistic therapy of alveolitis was founded from the importance of inflammation in the etiology. Indomethacin (3% age oily solution) was analysed on their effectiveness. In the control group was treated with chlorphenol-camphor-menthol-solution (ChKM) with addition of procain substance on the gauze strip. Indomethacin is significantly more active with regard to effectiveness, decrease of pain intensity and achievement of painlessness. The local therapy of alveolitis, is free of risk with solution out of Metindol--vials under dosage up to 6 milligram indomethacin substance.

Adult↗
PubMed1989

Effects of caffeine and doxapram perfusion on local cerebral glucose utilization in conscious rats.

The quantitative autoradiographic 2-[14C]deoxyglucose method was used to measure the effects of a continuous infusion of the respiratory stimulants, caffeine or doxapram, 18 mg/kg per h, on local cerebral glucose utilization in the adult male rat. Local cerebral glucose utilization was measured in 54 cerebral structures from different systems. Caffeine induced widespread increases in energy metabolism, resulting in a significant increase in glucose utilization in 25 structures out of the 54 studied. These increases were distributed within all systems studied, sensory, extrapyramidal motor, limbic and hypothalamic systems. In addition, caffeine induced a non-significant, 10-15%, increase in local cerebral glucose utilization in central respiratory areas. Doxapram infusion did not change the rates of glucose utilization in any of the structures. The rates of local cerebral glucose utilization were significantly lower after doxapram than after caffeine exposure in five cerebral areas, among which were three central respiratory areas. The results confirm the absence of side-effects of doxapram as compared to caffeine when used as respiratory stimulant, especially in neonates. These results also favor a preferentially central action of caffeine on respiratory areas and a more peripheral action of doxapram on chemoreceptors, at least at therapeutic levels.

Animals↗
PubMed1987

Effects of early chronic phenobarbital treatment on the maturation of energy metabolism in the developing rat brain. II. Incorporation of beta-hydroxybutyrate into amino acids.

The influence of phenobarbital (PhB) on the utilization of beta-hydroxybutyrate by the cerebral cortex and the cerebellum was studied in rats during postnatal maturation. The animals were treated from day 2 to day 35 after birth either by a daily injection of 50 mg/kg PhB or by saline. The rats were studied at 5 postnatal stages: 7, 10, 14, 21 and 35 days. Plasma beta-hydroxybutyrate and acetoacetate levels reached their peak values between 10 and 14 days after birth. The concentration of both ketone bodies was significantly higher in PhB- than in saline-treated rats between 10 and 35 days after birth. The total incorporation of [3-14C]beta-hydroxybutyrate into amino acids reached a peak value at 14 days after birth and was down to very low values at 35 days. It was higher in PhB- than in saline-treated rats. The specific radioactivity values of glutamate, glutamine, aspartate and GABA were significantly higher in PhB- than in saline-treated especially at 10 days after birth. These results demonstrate that a PhB treatment induces an increase in brain ketone body utilization in neonate rats, which is likely to balance the decrease in brain glucose utilization induced by this pharmacological treatment.

3-Hydroxybutyric Acid↗
PubMed1986

Prognostic factors in neuroblastomas treated in Denmark from 1943 to 1980. A statistical estimate of prognosis based on 253 cases.

Multivariate analysis on an unselected patient population consisting of all 253 children treated for neuroblastoma in Denmark during 1943 to 1980 shows that stage, age, and treatment given are independent prognostic variables. Calendar year of diagnosis, sex of the patient, and site of primary tumor were not significant prognostic factors. Further analysis shows that multimodal treatment with surgery, irradiation, and chemotherapy, especially in patients older than 1 year of age with Stage II disease, has influenced the survival significantly. The fact that age at diagnosis and the administration of chemotherapy have independent prognostic significance can be explained by the theory that all neuroblastomas are virtually congenital; therefore, the difference in age at diagnosis largely reflects the difference in growth rates of the tumor. Thus, according to this theory, age may be a measure of the probability of micrometastases in addition to the clinical extent or stage of the disease, as it represents the duration of the disease. Additional chemotherapy may thus have eradicated these micrometastases in the older children, since the age influence on Stage II disease disappeared when multimodal treatment was given in this study. The implications for treatment policy are discussed in view of this theory.

Age Factors↗
PubMed1986

Prognostic value of different staging systems in neuroblastomas and completeness of tumour excision.

Two hundred and fifty three patients were retrospectively assigned to eight different staging systems proposed for neuroblastomas, and the prognostic value of each staging system was evaluated individually. The ability of each system to predict prognosis was compared with the others and the system proposed by Evans et al found to be the best predictor, even better than the recently proposed Tumour-Nodes-Metastases staging system. This is probably due to the fact that factors other than the resectability of the tumour play a major role in the survival of these children. Age was found to have independent prognostic significance whatever staging system was used.

Age Factors↗
PubMed1985

Neuroblastomas treated at the four major child oncologic clinics in Denmark 1943-1980: an evaluation of 180 cases.

One hundred and eighty cases of neuroblastomas from the four child oncology clinics are reviewed. The overall cure rate was 24%. During the 38-year period, there was a significant increase in survival from 0% during the period of 1943-1950 to 32% during the period of 1971-1980. This improved survival rate is most likely a result of adjuvant chemotherapy. Forty percent of the patients appear chronically ill, which reflects the fact that nearly 60% have metastases when they are first seen. In localized disease (stages I-II), the prognosis was favourable (cure rate 69%), while the prognosis for disseminated disease (stage III-IV) was poor (cure rate 5%). A favourable outcome was seen in patients under 1 year (survival rate 46%), and in patients with primary tumours located in the neck or mediastinum (survival rate 48%). When related to stage, however, the survival rates for the former tumours were not significantly better in patients below 1 year or in patients with cervical or thoracic tumours. As is the case in other studies, we found that survival is significantly poorer in males.

Abdominal Neoplasms↗