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Biomedical subjects

R Frey

Publications and source records attributed to R Frey.

At least 73 records · Page 4Linked to original sources
PubMed1995

Immunologic reaction and viability of cryopreserved homografts.

Homograft cell viability after cryopreservation was investigated and cytoimmunologic monitoring was performed during the early postoperative course to research possible immunologic reactions after allograft aortic valve replacement. After cryopreservation, morphologic observations were made, a nonradioactive cell proliferation assay was used, and prostaglandin I2 secretion of the remaining endothelial cells was determined. Cytoimmunologic monitoring was performed daily within the first 3 weeks postoperatively. An increase of the activation index greater than 1 was rated as an immunologic reaction. Maintained metabolic activity of graft endothelial cells after cryopreservation was confirmed by prostaglandin I2 release (9.24 +/- 3.48 ng/cm2 basic release and 20.1 +/- 5.76 ng/cm2 when stimulated with 25 mumol/L Na arachidonic acid). Cell proliferation was indicated after graft incubation with the nonradioactive viability kit (0.27 +/- 0.9 at 450 nm). Cytoimmunologic examinations (n = 861) after homograft implantation showed a more intense activation in patients with ABO-incompatible grafts (activation index 2.1 +/- 1.6, n = 16) than in those with ABO-compatible grafts (activation index 1.3 +/- 0.8, n = 17). In these groups, the duration of activation by cytoimmunologic monitoring was 2.8 +/- 1.5 days and 1.3 +/- 0.6 days, respectively (p < 0.041). No activation was observed in 8 patients after xenograft valve replacement (p < 0.01). Our data indicate that cryopreservation of homograft valves represents a cell- and tissue-protective preservation method. Postoperatively, all homograft valves caused immunologic reactions, which were reversible without immunosuppression treatment.

ABO Blood-Group System↗
PubMed1995

Technetium-99m-HMPAO SPECT imaging of cerebral blood flow during REM sleep in narcoleptics.

UNLABELLED: This study was performed to demonstrate global and regional cerebral blood flow (rCBF) changes during rapid eye movement (REM) sleep in six patients with narcolepsy using SPECT and 99mTc-HMPAO. METHODS: Global and hemispheric HMPAO uptake as well as regional (RI) and asymmetry indices were estimated and compared between polysomnographically verified sleep onset (SO)REM and wakefulness. RESULTS: The estimated global HMPAO uptake did not differ between the two conditions indicating a similar overall cortical activity. During (SO)REM sleep, hemispheric HMPAO uptake as well as calculated RI, especially in the supratemporal plane, were significantly higher on the right side than contralateral. This indicates an initially right-sided cerebral activation and a special involvement of the right, nondominant hemisphere during dreaming which is responsible for visual-spatial perceptions. Furthermore, increased RI in superior parietal regions during sleep were evident and were explained by an activation of associative areas. In thalamic regions, decreased RI were found during sleep, which may reflect thalamic dysfunction. CONCLUSION: A definite assignment of these CBF alterations to (SO)REM sleep might be problematic because of unstable boundaries between sleep stages in narcolepsy. On the other hand, specificity of such CBF changes for narcolepsy requires further study.

Adolescent↗
PubMed1994

Integrity and viability of homograft valves.

Since it has been suggested that the leaflet tissue viability influences durability after homologous valve replacement, we compared different harvest and preservation techniques in order to examine the quality and smoothness of homograft conservation. We analyzed human aortic and pulmonary valve leaflets obtained from 'heart-beating donors' (HBD) during heart transplantation and from 'non-heart-beating donors' (NHBD) during coroner's autopsies. Valves were either cryopreserved in liquid nitrogen or stored at 4 degrees C in nutrient medium similar to the procedure reported in our protocols of the homograft bank system. All grafts from NHBD had been antibiotically sterilized for 3 days beforehand. Morphological observations were made using light and electron microscopy and, in order to characterize the endothelial cell viability, a non-radioactive cell proliferation assay was used. The PGI2 secretion of the remaining endothelium was defined as the 6-keto-prostaglandin F1 alpha metabolite by an enzyme immunoassay. Observations in the scanning electron microscope revealed that, after cryopreservation, homografts show an almost confluent endothelium when processed within 24 h after harvest from HBD, but lack endothelial cells when obtained from NHBD. Cryopreserved grafts from NHBD exhibited an altered tissue structure with edema and vacuolization within the spongiosa of the leaflets as well as irreversible cell damage when examined under the light and transmission electron microscope. That the metabolic activity of HBD homografts was maintained was confirmed by proven PGI2 secretion (6150 +/- 1200 pg/3 ml M199 after cryopreservation), whereas specimens from NHBD showed a reduced (1950 +/- 730 pg/3 ml M199) and, after cryopreservation, almost no release (P < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Insomnia in generalized anxiety disorder: polysomnographic, psychometric and clinical investigations before, during and after therapy with a long- versus a short-half-life benzodiazepine (quazepam versus triazolam).

Within a double-blind, comparative study on the effects of the long-half-life benzodiazepine (BDZ), quazepam, and the short-half-life BDZ, triazolam, on clinical symptomatology, sleep and anxiety of 45 patients with insomnia based on a mild to moderate generalized anxiety disorder (GAD) (ICD-9 code: 307.42-1, 300,0; ASDC-APSS-Code: A.2.a), we compared, in a first step at baseline, drug-free polysomnographic and psychometric data of 22 patients recorded in the laboratory (L-group) and 21 patients recorded by the Oxford Medilog 9000 system at home (H-group) with those of normal controls. Sleep efficiency, total sleep time, wake within total sleep period (middle insomnia) and wake before buzzer (late insomnia) were significantly deteriorated in both patient groups as compared with controls, while sleep induction time only differed significantly in home recordings. Regarding sleep architecture, stage (S)2 was reduced, S3 and S4 increased in the H-group only, while no intergroup differences were seen in S1, SREM and REM latency. Subjective sleep quality was reduced in both patient groups, but not awakening quality. Psychometric tests in the morning demonstrated for the noopsyche, only a significantly deteriorated psychomotor activity in both patient groups. In the thymopsyche, evening well-being and mood in the morning were reduced in both the L- and H-group, affectivity and morning well-being only in the H-group. The psychopharmacological part of the study was completed by 40 patients (there were 4 drop-outs in the triazolam, 1 in the quazepam group). They were treated after 1 week placebo with either 15-30 mg (median 15 mg) quazepam or 0.25-0.5 mg (median 0.25 mg) triazolam for 4 weeks, and thereafter for 2 weeks with placebo. Anxiety (rated by HAMA and SAS) improved significantly with both drugs and remained improved throughout 2 weeks post-drug placebo, with quazepam being slightly superior to triazolam. Polysomnography demonstrated a shortened sleep onset only after quazepam. Sleep efficiency improved after acute administration of both drugs, but the improvement was maintained by quazepam only (tolerance development with triazolam). Rebound insomnia was observed only in the 1st post-triazolam placebo night (significant intergroup difference based on confirmatory testing). S2 increased, S3 + S4 decreased under and after quazepam, which represents a normalization in home-recorded GAD patients. S1 decreased with both drugs, SREM only under quazepam. Subjective sleep quality behaved very similarly to objective sleep efficiency. Awakening quality improved after acute therapy with both drugs, somatic complaints only with quazepam.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1993

Color vision deficiencies in the course of acute alcohol withdrawal.

Thirty-six male patients with a diagnosis of chronic alcoholism were detoxified and color vision tests were performed on day 4, 11, and 32 of their abstinence on an inpatient basis (Ishihara color plates, Nagel anomaloscope, three color-matching tests according to Farnsworth). Of the 36 patients, 47.2% manifested color vision deficiencies. The frequency of congenital red/green defects (11.1%) and a ratio of 3:1 deutan/protan defects showed no significant difference from the incidence in the normal population. In 36.1%, manifest acquired color vision deficiencies were diagnosed. Within the course of withdrawal, a marked improvement of these disturbances could be proved. The degree of the disturbance seems to correlate with the severity of withdrawal symptoms, but seems to be unrelated to acute toxic effects of alcohol, nicotine, or medication.

Adult↗
PubMed1993

Treatment of the alcoholic organic brain syndrome: double-blind, placebo-controlled clinical, psychometric and electroencephalographic mapping studies with modafinil.

In a double-blind study 40 abstinent hospitalized male patients with an alcoholic organic brain syndrome (OBS; ICD 9: 291.2) were treated for 6 weeks with either placebo or 200 mg modafinil b.i.d. Modafinil (CRL 40476) is a vigilance-promoting, putative central alpha 1-adrenergic agonist with a pharmacological profile quite different from that of amphetamine. Clinical investigations demonstrated that the spontaneous remission of the alcoholic OBS was augmented and accelerated by modafinil, which was found significant as compared with placebo by confirmatory statistics in the target variable, the Clinical Global Impression scale. The drug was well tolerated. Psychometric tests revealed significant improvement of the noopsyche after modafinil as compared with placebo, while the thymopsyche and psychophysiological measurements were not affected. Electroencephalographic mapping showed significant differences between the central effects of modafinil and placebo indicating an improvement of vigilance under modafinil. Typical vigilance-promoting properties were seen after acute drug administration, were less evident before the morning dose after chronic treatment but re-occurred after super-imposed daily drug administration. Thus, our clinical, psychometric and neurophysiological investigations in alcoholic OBS patients demonstrated a therapeutic effect of modafinil in the early phase of abstinence.

Adult↗