Biomedical subjects

T Niethammer

Publications and source records attributed to T Niethammer.

6 recordsLinked to original sources

PubMed1983

[Diagnosis of internal abscesses by scintigraphy: results of a method using purified granulocytes].

In the 111-indium-leukocyte scan method described by M. L. THAKUR et al. in 1977 for the diagnosis of abdominal abscesses the whole leukocyte fraction from a blood sample is labeled and injected into patients. We propose a modification in which purified granulocytes are used. The results of 43 granulocyte scans show that this modification does not diminish the sensitivity of the method. Furthermore, it allows the detection of abscesses in a shorter time (2-4 hours after injection) and with 111-indium doses (200 muCi) at least 3 times lower than in the original method. Increased specificity can also be expected.

Abdomen↗

PubMed1982

Electrophysiological measures (CNV--EEG) and nitrous oxide at low doses in man.

Nitrous oxide (N2O) is a widely used inhalational anesthetic gas, but its exact mode of action and its distribution in the CNS are not yet well known. The aim of this research was to study the effects of N2O at low doses (10 percent) in the CNS of humans. Five healthy volunteers were tested. Contingent Negative Variation (CNV), Reaction time (RT) and quantified EEG recordings were taken while subjects were breathing air and then N2O. A significant reduction of the post-imperative positive CNV components during N2O inhalation was observed; no changes in EEG power spectrum and RT values were seen. These results could be consistent with an early N2O interference with processes underlying CNV resolution, while vigilance and attention were still maintained.

Adult↗

PubMed1982

[Quantified EEG and CNV changes during inhalation of nitrous oxide].

The present study constitutes an approach to the action mechanisms of nitrous oxide (N2O) by assessing both the subjective effects induced by the inhalation of this anaesthetic gas, and their electrophysiological correlates, i.e., spontaneous EEG, analyzed by a Fourier algorithm, AEP and CNV. The experiment was conducted single blind in 9 volunteers under 3 recording conditions: inhalation of air, of a mixture of 25% N2O--75% O2, and of a mixture of 50% N2O--50% O2. A latin-square design was used. Polymorphic effects of N2O were evidenced on behaviour and on CNS: some of the behavioural manifestations could evoke a depression of SNC: muscle relaxation with difficulty of motor initiation, psychomotor slowing, slower EEG with diminution of the percent alpha component and increase in the percent theta and delta, loss of amplitude of both exogenous (N1) and endogenous (P300) components of the AEP. Conversely, other manifestations were observed that are compatible with an activation of the CNS: increase of sensory perceptions, appearance of perceptual illusions, maintenance of a high CNV amplitude and lengthening of its duration. This dual effect of N2O suggests a dissociative action at the different levels of the CNS.

Adult↗

PubMed1982

[Positron tomographic study of the behavior of 13N-labeled nitrous oxide in the human brain].

The synthesis of 13N-labelled nitrous oxide was made following NICKLES' method. After a partial denitrogenisation by breathing pure oxygen for 3 min, the subject inhaled a bolus of 13N-labelled nitrous oxide diluted in 2 l of oxygen (a mixture of 5% 13N2O and 95% O2). After an apnea of 30 sec the subject began to breathe in a closed respiratory system containing a mixture of 10% N2O and 90% O2. Eight images of the brain taken at level OM + 3 in 4 subjects showed an important uptake in the cerebellum and in the frontal and temporal cortex. Six min after inhalation of the bolus, the radioactivity in the cerebellum showed a clear decrease, whereas little decrease was observed in the frontal cortex and only a slight decrease in the temporal cortex. In order to suppress the activity due to the vascular comportment, an experiment was performed under the same conditions as the previous one, but using sodium pyrophosphate containing tin and 25 mCi of Tc-99m pertechnetate. The correction factors vary from 0.394 to 0.894 depending on the R.O.I. The activity curves after correction showed a predominance in the frontal cortex. It can therefore be concluded that some specific zones of the brain are receptive to N2O and in particular the frontal cortex. These results were compared with the data obtained from the electrophysiological recording of the frontal region of the brain (C.N.V.: Contingent Negative Variation).

Adult↗

PubMed1981

Radionuclide venography using continuous Kr-18 m infusion: preliminary note.

Continuous infusion of Kr-81m presents important advantages compared to the commonly used radionuclides for venography. High count rates can be accumulated, and a high resolution collimator can be employed to ensure good quality images. The study can be repeated immediately and multiple views can be performed until a satisfactory result is obtained. The production of radionuclide from a Rb-81--Kr-81m generator suitable for intravenous infusion is almost the same as that which is suitable for ventilation. The same generator can first be used for venography and then for ventilation imaging to complete the work-up patients suspected of having thromboembolic disease.

Evaluation Studies as Topic↗

PubMed1979

Glucose-enriched dialysate and tolerance to maintenance hemodialysis.

10 patients entered a controlled 4-week study to evaluate the effect of a glucose-enriched dialysate (400 mg/100 ml) on hemodialysis tolerance. Headache during and after dialysis and post-dialysis fatigue decreased in a statistically significant manner. The average glycemia was only moderately increased with an adequate insulin response. Blood cholesterol and triglycerides did not vary signifcantly during this short study period.

Adult↗