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Biomedical subjects

F Hoffmann

Publications and source records attributed to F Hoffmann.

At least 127 records · Page 7Linked to original sources
PubMed1984

Lack of significant correlation between circadian profiles of valproic acid serum levels and epileptiform electroencephalographic activity.

Using mobile long-term electroencephalographic (EEG) monitoring in 7 absence epilepsy patients, the course of spike-wave discharge rate before and during valproate monotherapy was measured and compared to the profile of valproic acid serum level. Correlation analysis was done, taking into account an eventual time delay between drug concentration and effect on EEG. No significant correlation was found when comparing serum levels with the actual discharge profile or with the profile of changes in discharge rate.

Adolescent↗
PubMed1984

Valproic acid in breast milk: how much is really there?

Valproic acid (VPA) concentrations were measured by a sensitive and highly specific gas chromatographic/mass spectrometric assay in breast milk from 16 patients treated with VPA during 17 lactation periods. The range of VPA levels in 36 breast milk samples was 0.4-3.9 micrograms/ml (mean 1.9 +/- 1.2 microgram/ml). During the investigations of breast milk it was found that the concentration of total VPA in breast milk was not much higher than that of unbound VPA. These findings agree with clinical observations of infants fed with milk from VPA-treated mothers.

Adult↗
PubMed1984

Protein binding of valproic acid in maternal and umbilical cord serum.

The serum valproic acid levels of 18 maternity patients at the time of delivery were compared with the valproic acid levels in the umbilical cord serum. The levels in the umbilical cord serum were 1.1-4.6 times higher than those in the maternal serum, with a mean value of 1.38. One explanation for this difference apparently is an increased protein binding of valproic acid in the infant's serum. Protein binding was determined in nine patients, in six by equilibrium dialysis and in three by ultrafiltration. The median value of the free fraction of valproic acid was 9.1% (range, 5.8-16.4%) in the umbilical cord serum (equilibrium dialysis) and 15% (range, 12.7-35.3%) in the maternal serum. The difference between the infant and the maternal serum is significant.

Adolescent↗
PubMed1984

[Combination therapy with carbamazepine and valproic acid in problem cases at an outpatient epilepsy clinic].

A total of 64 problem patients with epilepsy (42 retrospective evaluations, 22 prospective cases) was treated with the combination of carbamazepine and valproic acid. Most frequent seizure types were tonic clonic (focal origin or primarily generalized), complex partial ones, and absences. Best results were observed in patients with tonic clonic seizures in contrast to complex partial ones. The pattern of adverse reactions (none of significant severity) was according to those of monotherapies with the compounds. In cases with relevant improvement serum levels of carbamazepine and valproic acid were within the range commonly described for monotherapies.

Adult↗
PubMed1984

The effect of laser microsurgery on cytoplasmic strands and cytoplasmic streaming in isolated plant protoplasts.

Cytoplasmic strands of actively streaming isolated callus derived protoplasts of higher plants were subjected to laser microsurgery. Typically, the irradiated strand retracted and cytoplasmic streaming stopped in the entire cell. At the same time, all cytoplasmic strands disintegrated, and formerly not totally spherically shaped protoplasts became spherical. This result indicates tension as a stability factor of cell shape and the cytoplasmic make-up and demonstrates that the nonspherical shape of these protoplasts is not due to cell wall residues. Cytoplasmic streaming as well as the strands were quickly reestablished and often the irregular shape of the protoplast appeared again. Treatment of unirradiated cells with cytochalasin B showed similar effects. The results are discussed with respect to the involvement of cytoskeletal elements in cytoplasmic streaming and organization.

Cytochalasin B↗
PubMed1983

[Current status of the standardization of air impulse tonometers and their evaluation--as an example: the Non-Contact Tonometer II].

The standard values and tolerances used in the assessment of the clinical efficiency of different types of tonometers are once again demonstrated. Investigations carried out in accordance with the existing test plan for comparative clinical measurements using two non-contact tonometers II (NCT II) and a calibrated applanation tonometer as a reference instrument in 155 patient eyes showed that both the regression equation and the scattering of the individual values around the regression curve satisfy the conditions of clinical assessment criteria. Of the individual values, 2.6% are outside the 95% limits. Following a brief illustration of the measuring principle of the NCT II, a test procedure is described for this type of tonometer. It consists of a torsion balance mounted on a cross-sliding carriage with a small mirror 2.5 mm in diameter and a control balance. A lens equipped with a centering cross is used for adjustment to the nominal distances of 11 mm between the nozzle and the cornea. This test procedure makes it possible to determine whether the digital display of any particular NTC II deviates from the nominal value by not more than +/- 1 digit in the range between "12" and "30" and by not more than +/- 2 digits between "31" and "50".

Calibration↗
PubMed1983

Effect of valproic acid treatment on spike-wave discharge patterns during sleep and wakefulness.

7 patients suffering from absences were recorded before antiepileptic treatment, in the early phase of valproate monotherapy and after having reached steady state. Recordings made with the Oxford-Medilog 4-channel cassette recorder were analyzed visually as well as by a computerized s-w pattern recognition approach, the latter facilitating quantification of pattern characteristics (number, amplitudes and duration of spikes and waves). Measurements were made separately for epochs of wakefulness and sleep. Compared to the premedication phase the amount of s-w discharges in 24 h showed an average reduction of more than 90%. For the majority of the patients, 24-hour discharge profiles showed a maximum in the early morning. Duration and amplitude of both spike and wave elements was higher during sleep. For the waking state, the ratio wave amplitude/spike amplitude was found to be increased under medication.

Adolescent↗
PubMed1982

Use of stable labelled carbamazepine to study its kinetics during chronic carbamazepine treatment.

The kinetics of carbamazepine using stable labelled 15N-carbamazepine was studied in 4 epileptic patients who had been treated with it for at least 6 months. There was a decrease in half-life (12.3 +/- 0.8 h) and an increase in total plasma clearance (58.0 +/- 6.5 ml/min) as compared to single dose studies, which provide further evidence that carbamazepine induces its own metabolism during long-term treatment. Analysis of the urinary metabolites indicated induction of the epoxide-trans-diol pathway. Predicted and observed steady-state plasma levels were in good agreement, thus demonstrating that the use of stable labelled drugs is a useful technique to elucidate changes in kinetics and metabolism which may occur in patients during long-term treatment.

Administration, Oral↗
PubMed1982

Psychological identification of breast cancer patients before biopsy.

Fifty-six women admitted consecutively for a breast biopsy were interviewed on the day prior to the operation. Interviewer ratings and blind ratings (audiotapes) allowed a [statistically significant (alpha = 5%)] differentiation of women in whom the biopsy revealed a cancer from those whose tumor was benign. The ratings took into account characteristics assumed to be typical of the women with cancer: (1) being inaccessible or overwhelmed when interviewed; (2) emotional suppression with sudden outbursts; (3) rationalization; (4) little or no anxiety before the operation; (5) demonstration of optimism; (6) superautonomous self-sufficiency; (7) altruistic behaviour; (8) harmonization and avoidance of conflicts. On the basis of the interviews the interviewer and a blind rater predicted the correct diagnosis in 83% and 94% of all cancer patients and in 71% and 68% of all benign cases. This result is also significant (alpha = 5%). The identified psychological syndrome was found in all breast cancer patients but also in a quarter to a third of the patients with benign nodes. We interpret it as a long-standing defensive pattern adopted in the face of extreme emotional stress. A possible etiological significance for the cancerous disease cannot be derived from this study.

Adult↗
PubMed1982

[Notes on clinical criteria for the evaluation of tonometers (author's transl)].

The limits of error existing hitherto in verifying the measuring force of applanation tonometers are to be extended in the IOP range above 4.0 kPa (10 mmHg). Relevant ISO proposals submitted by Japan and the Federal Republic of Germany are under discussion. The increase in the amplitudes of pulsations in the eye with increasing intraocular pressure i.e., about 10% per 1.33 kPa (10 mmHg), necessitates a restatement of the limits of error for deviations of individual values around the regression line in clinical control measurements with tonometers whose measuring process terminates in split seconds. Equations for parabolic limits of error are given.

Animals↗
PubMed1982

[Carcinogenicity test in long-term bioassay of Fermosin-yeast grown on petroleum hydrocarbons].

To test "fermosinR'-yeast grown on petroleum hydrocarbons for carcinogenic potency the product was fed chronically at a dietary level of 15% to male and female rats (Wistar). Animals of the control group received the Institute's stock diet, similar to the yeast diet but without "fermosinR'. Feeding of "fermosinR'-diet did not affect the incidence nor the latency period nor the type of tumors compared with the control rats. Studies in mice (XVII) included two separate experiments. In the first one the dorsal skin of the animals was painted by extracts from yeast twice weekly and treated with the co-carcinogenic agent croton oil once a week. In the second experiment the mice were painted by extracts from pork of animals feed with "fermosinR'. The results obtained in rats and in mice did not reveal any evidence for carcinogenic potency of "fermosinR'-yeast.

Administration, Oral↗
PubMed1982

Rabbit corneal allograft survival following topical administration of cyclosporin A.

Cyclosporin A (CS-A), selectively inhibited cellular immunity, delayed the skin graft-induced rejection of corneal allografts in rabbits when administered subconjunctivally in the dose of 3 mg/kg/day or in the form of 5% water-soluble drops five times daily for 28 days. The subconjunctival application of CS-A was irritating, whereas the topical instillation of the water-soluble preparation was well tolerated. The corneal grafts were rejected after discontinuation of the therapy. Rejection was confirmed by scanning and transmission electron microscopy. The mechanism by which CS-A delayed corneal graft rejection seems to depend mainly on the specific and/or the nonspecific effect of topical CS-A on lymphocytes.

Administration, Topical↗