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Biomedical subjects

P Frank

Publications and source records attributed to P Frank.

143 records · Page 8Linked to original sources
PubMedDate not supplied

Thermal destruction of benzene.

The thermal destruction of benzene in methane/air flue gas is studied experimentally using an atmospheric laminar flow reactor in laboratory scale. The reactor is operated at four different fuel equivalent ratios (phi = 0.06, 0.1,0.5, 3.7), and temperatures in the range from 850 to 973 K and realises a residence time of 5 s. Stable-species concentrations are measured by gas chromatography (GC) and high-pressure liquid chromatography (HPLC), where phenol, acetylene, formaldehyde, acrolein, methane and acetaldehyde are the major hydrocarbon products besides CO and CO2. The augmentation of the temperature from 850 to 973 K increases the benzene conversion rate from 55% to 99%. The experimental results for one fuel equivalent ratio (phi = 0.5) are compared to the benzene model proposed by Emdee et al. (J. Phys. Chem. 92 (1992) 2151-2161). A fair agreement is observed for the benzene consumption and the CO production throughout the temperature range considered here. The small hydrocarbons are not very well matched, which requires further research on the sub-models. Our experimental results on laboratory scale provide a database for the modelling of benzene oxidation in waste incinerators.

Journal Article↗
PubMedDate not supplied

Differential effects of organic hydroperoxides and hydrogen peroxide on proteolysis in human erythrocytes.

The effects of tert-butyl hydroperoxide, cumene hydroperoxide, and hydrogen peroxide on proteolysis in human red blood cells have been examined. The organic hydroperoxides effectively stimulated the rate of protein degradation in red cells and in hemolysate; in contrast, H2O2 addition was without significant effect in either system. tert-Butyl hydroperoxide or cumene hydroperoxide (8 mM) increased the rate of protein degradation in red cells 2.3- and 4-fold, respectively, relative to control as monitored by tyrosine release. In hemolysate, tert-butyl hydroperoxide and cumene hydroperoxide, present at 8 mM, produced a 2- and 3-fold increase in the rate of protein degradation, respectively, as compared to controls. Hydroperoxide-stimulated proteolysis in red cells or in hemolysate was concentration-dependent and reached saturation at 8 mM hydroperoxide. The reaction was linear for 2 h after which a plateau was reached. In contrast to the results observed for the organic hydroperoxides, H2O2 (100 or 200 mM) addition either alone or in the presence of the catalase inhibitor 3-amino-1,2,4-triazole (50-200 mM), failed to stimulate proteolysis. N-Acetylcysteine (20 mM) and dimethylthiourea (50 mM) inhibited the rate of hydroperoxide-stimulated proteolysis in red cells by approximately 50 and approximately 35%, respectively, and in hemolysate by 25 and 40%, respectively. The hydroxyl radical scavengers methyl sulfoxide (50 mM) or dimethylfuran (50 mM), metal ion chelators, or spin traps failed to decrease significantly the rate of organic hydroperoxide stimulated proteolysis. In addition, inhibitors of the calpain/procalpain system in red cell or hemolysate incubations challenged by organic hydroperoxide were without significant effect on the rate of proteolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMedDate not supplied

[5 years' experiences with the Gersthof polyethylene peg-anchored acetabulum].

The acetabular socket "Model Gersthof" is a spheric polyethylene component which can be anchored cement-free by means of three symmetrically arranged pegs at the outside. Between July 1979 and October 1986, 1316 implants of cement-free sockets were performed at our own department. The evaluation of the socket was based on the criterium of radiological instability (= aseptic loosening). After five years of observation, this design-oriented evaluation of success shows a survival of 92% +/- 2.9%.

Acetabulum↗
PubMedDate not supplied

[Simple mandibular bone cysts].

3 cases of simple bone cyst occurring in young adults are presented. Roentgenographic findings and criteria for diagnosis are explained. Rapid bony replacement of the cavity confirm the nonradical surgical intervention.

Adolescent↗
PubMedDate not supplied

[Late results of conservative condylar fracture treatment].

116 patients with healed condylar fractures were investigated between a half and six years after the occurrence. 20 of them had pain in the joint, 19 of them showed a deviation of the mandible when opening the mouth. The margin distance of the incisors were 40.8 mm, in 5 cases less than 30 mm. The X-ray showed in 31 cases a dislocation of the fragments, in 6 cases a resorption of the proc. articularis. There was no correlation between pain, deviation, dislocation and the margin distance of the incisors. It is concluded that the anatomic exactly reposition of the fragments is not necessary for the undisturbed function of the temporomandibular joint.

Bone Resorption↗
PubMedDate not supplied

Effects of mitoxantrone and bisantrene on platelet aggregation and prostaglandin/thromboxane biosynthesis in vitro.

The effects of mitoxantrone and bisantrene on agonist-stimulated platelet aggregation, prostaglandin E2 and thromboxane B2 production were examined and results compared with those produced by indomethacin and acetylsalicylic acid. Both mitoxantrone and bisantrene effectively inhibited collagen-, ADP-, and epinephrine-stimulated platelet aggregation. Collagen (0.54 microgram/ml)-stimulated platelet aggregation was inhibited by 50% at 60 microM mitoxantrone and 8 microM bisantrene. The concentration of drug required for inhibition of platelet aggregation varied inversely with the level of collagen stimulus employed. Mitoxantrone and bisantrene inhibited both the first and second phase of epinephrine-stimulated platelet aggregation. Complete inhibition of the second wave of aggregation was obtained at greater than 160 microM mitoxantrone and 16 microM bisantrene. Mitoxantrone is comparable in potency to acetylsalicylic acid which inhibited the second wave of epinephrine-stimulated aggregation 50% at 160 microM, whereas bisantrene may be compared to indomethacin which produced complete inhibition of aggregation at 16 microM. Production of PGE2 and TXB2 in epinephrine-stimulated platelets was inhibited by both drugs with 50% inhibition of PGE2 production occurring at 12 microM mitoxantrone and 3 microM bisantrene. Thromboxane B2 production was inhibited by 50% at 10 microM mitoxantrone and 5 microM bisantrene. Indomethacin inhibited PGE2 and TXB2 production 50% at 4 microM. Thus mitoxantrone and bisantrene inhibit platelet aggregation and prostaglandin production which may be of significance in metastasis and in prostaglandin-mediated physiologic and immune responses.

Adult↗
PubMedDate not supplied

[Anesthesia in the early surgical therapy of myelomeningocele].

Anaesthetic procedures in surgical repair of meningomyelocele in pediatric patients with particular reference to the problems concerning the specific pathology and the newborn age are reported. Authors consider that surgical repair in the first days of life assures a lesser incidence of leptomeningeal infections and a better functional improvement without an important increase of the anaesthetic risk.

Adolescent↗
PubMedDate not supplied

[Non-recurrent inferior laryngeal nerve].

The Authors describe a case of non recurrent inferior laryngeal nerve located on the right side observed during anatomical studies of the innervation of the larynx. The description is accompanied by photographic documentation which shows the anomalous course of the nerve and its abnormal relationship with the right subclavian artery, also anomalous. The embryological nature of such anatomical variations is discussed followed by considerations concerning possible consequences with regard to clinical aspects and thyroid surgery. Furthermore, the Authors indicate clinical signs that may suggest the presence of such anomaly so as to avoid anatomical or functional damage of the nerve which, although anomalous, plays an important role in coordinating breathing and phonation.

Humans↗
PubMedDate not supplied

[Structure and aggregation of histones. I. Influence of the ionic composition of the medium on the structure and effectiveness of the intermolecular relationships of histone F2a (H2A+H4)].

The investigation of fluorescence and light-scattering change of histone F2a, ribonuclease, tyrosine, N-acetyltirosinamide, methyl ether tyrosine by the concentration increasing of NaCl, MgCl2, Na2SO4 in the surrounding medium was carried out. In the case of used salts the changes of tertiary structure and histones aggregations depend on the anion type, which is presented in the environment. The tertiary structure of histones formed in the presence of salt is stabilized by weak (hydrophobic and hydrogenic) interactions.

Chemical Phenomena↗