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Biomedical subjects

P Bey

Publications and source records attributed to P Bey.

At least 127 records · Page 7Linked to original sources
PubMed1986

Abdominal recurrences in Wilms' tumours: a report from the SIOP Wilms' tumour trials and studies.

The Wilms' tumour trials and studies conducted from 1971 to 1980 registered 1042 patients. Of these, 82 patients developed an abdominal recurrence. Particulars of these were studied. Half of the recurrences occurred in stage III patients. Often several untoward prognostic factors could be identified, such as large tumour size, difficult operation, incomplete excision, peritoneal adhesions or metastases, tumour extending to renal vein or vena cava. A tumour rupture increases the chance for an abdominal recurrence, especially if appropriate radiotherapy is not given. In many of these cases, postoperative radiotherapy seems to have been insufficiently tailored to the operative findings. For stage III cases, a careful discussion between surgeon, radiotherapist, and pathologist should lead to the optimal radiotherapy field size and dose for each individual patient, so that the risk of abdominal recurrence can be reduced.

Abdominal Neoplasms↗
PubMed1986

Inhibition of polyamine biosynthesis by alpha-difluoromethylornithine in African trypanosomes and Pneumocystis carinii as a basis of chemotherapy: biochemical and clinical aspects.

The symposium provided dramatic evidence of the value of the use of polyamine inhibition via alpha-difluoromethylornithine (DFMO, eflornithine) for advances in chemotherapy of Trypanosoma brucei gambiense sleeping sickness and Pneumocystis carinii pneumonia in acquired immune deficiency syndrome (AIDS) and also for further understanding the metabolic importance of the ubiquitous polyamines in these organisms.

Acquired Immunodeficiency Syndrome↗
PubMed1986

[Treatment of thyroid ophthalmopathies by external orbital radiotherapy].

From January, 1977, through December 1983, 62 patients with thyroid edematous ophthalmopathy were given external orbital radiotherapy according to S.S. Donaldson's technique: 5,5 MV photons produced by a linear accelerator were used to irradiate the muscular conus, with a total of 20 grays in 10 sessions over 2 weeks. Good results were obtained in 46 patients (77%). This simple therapy may be a first choice in recent ophthalmopathy.

Adult↗
PubMed1985

Specific inhibition of polyamine oxidase in vivo is a method for the elucidation of its physiological role.

N1-Methyl-N2-(2,3-butadienyl)-1,4-butanediamine (MDL 72521) and N1,N2-bis(2,3-butadienyl)-1,4-butanediamine (MDL 72527) are specific, potent, enzyme-activated, irreversible inhibitors of polyamine oxidase in vitro. These compounds are also capable of completely inhibiting polyamine oxidase in mouse tissues at intraperitoneal doses greater than 20 mg/kg. Enzyme activity reappears in the various organs within 2-3 days to 50% of the control values. Irreversible inhibition of polyamine oxidase in mice led to decreased putrescine (30-40%) and spermidine (10-20%) levels in liver and some other organs. At the same time N1-acetylspermidine and, to a lesser extent, N1-acetylspermine were accumulating at rates which are assumed to be related to the rates of polyamine degradation. Even after treatment with polyamine oxidase inhibitors over a period of 6 weeks at doses which produced complete inhibition of polyamine oxidase in all organs, including the brain, neither toxic effects nor changes in body weight or behaviour were observed.

Animals↗
PubMed1985

Enzyme-activated irreversible inhibitors of monoamine oxidase: phenylallylamine structure-activity relationships.

Seventeen 2-aryl-3-haloallylamine derivatives were prepared and evaluated as inhibitors of monoamine oxidase (MAO, EC 1.4.3.4). The synthesis of these compounds was achieved from either alpha-methylstyrene or ring-substituted phenylacetic acid derivatives. With one exception, these 2-arylallylamines were found to be enzyme-activated, irreversible inhibitors of MAO. The most potent inhibitors were ring-substituted derivatives of (E)-2-phenyl-3-fluoroallylamine with IC50 values ranging from 10(-6) to 10(-8) M. Selectivity for the A and B form of MAO was found to depend on the nature of aromatic ring substitution. In general, hydroxyl substitution favored the inactivation of the A form of MAO, while very selective B inhibitors were obtained when the aromatic ring was substituted with a 4-methoxy group. (E)-2-(4-Methoxyphenyl)-3-fluoroallylamine and (E)-2-(3,4-dimethoxyphenyl)-3-fluoroallylamine proved to be in vitro as selective for the B form of MAO as deprenyl.

Allylamine↗
PubMed1985

Inhibition of monoamine oxidase selectively in brain monoamine nerves using the bioprecursor (E)-beta-fluoromethylene-m-tyrosine (MDL 72394), a substrate for aromatic L-amino acid decarboxylase.

(E)-beta-Fluoromethylene-m-tyrosine (FMMT) is a dual-enzyme-activated inhibitor of monoamine oxidase (MAO). The compound is not an inhibitor per se but is decarboxylated by aromatic L-amino acid decarboxylase (AADC) to yield a potent enzyme-activated irreversible inhibitor of MAO, (E)-beta-fluoromethylene-m-tyramine, which shows some selectivity for inhibition of MAO type A. Decarboxylation of FMMT was demonstrated in vitro using hog kidney AADC and in vivo in rats by the ability of alpha-monofluoromethyldopa (MFMD), a potent inhibitor of AADC, to prevent MAO inhibition produced by FMMT. In isolated synaptosomes, FMMT was decarboxylated by AADC, and, furthermore, the compound was actively transported into these isolated nerve endings. An active transport into the CNS has also been demonstrated in vivo by performing competition experiments with leucine. To demonstrate that FMMT is preferentially decarboxylated within monoamine nerves of the CNS, the nigrostriatal 3,4-dihydroxyphenylethylamine (dopamine) pathway of rats was unilaterally lesioned with 6-hydroxydopamine or infused with MFMD. Under these conditions, MAO inhibition produced by orally administered FMMT in the striatum ipsilateral to the lesion or infusion was markedly attenuated. Combination of FMMT with an inhibitor of extracerebral AADC, such as carbidopa, protected peripheral organs against the MAO inhibitory effects and concomitantly enhanced MAO inhibition in the CNS. Such combinations had a greatly reduced propensity to augment the cardiovascular effects of intraduodenally administered tyramine, when compared with FMMT given alone or with clorgyline, a selective inhibitor of MAO type A. The results obtained with FMMT suggest the possibility of achieving selective inhibition of MAO within monoamine nerves of the CNS and, further, suggest that combination of FMMT with an inhibitor of extracerebral AADC will reduce the propensity of this inhibitor to produce adverse interactions with tyramine.

Animals↗
PubMed1985

[A case of vertebral chondroblastoma].

The authors have observed a case of cervical chondroblastoma in a child aged nine years. Clinically there was a mediastinal syndrome, with pulmonary tract infection. Resection was achieved in two stages. One year later a local recurrence was treated by a third resection, followed by radiotherapy. Three years later there was no sign of recurrence. A review of the literature summarises the difficulties of diagnosis.

Cervical Vertebrae↗
PubMed1984

Inhibition of growth of Mycoplasma dispar by DL-alpha-difluoromethyllsine, a selective irreversible inhibitor of lysine decarboxylase, and reversal by cadaverine (1,5-diaminopentane).

DL-alpha-Difluoromethyllysine was shown to be a potent inhibitor of lysine decarboxylase from Mycoplasma dispar. The inhibition appeared to be specific since neither difluoromethylornithine nor difluoromethylarginine, known to inhibit other decarboxylases, inhibited the reaction catalyzed by lysine decarboxylase in extracts of M. dispar. Inhibition was irreversible since extensive dialysis could not overcome the inhibitory effect exerted by difluoromethyllysine. Difluoromethyllysine (1 mM) also totally blocked the growth of M. dispar when added at the beginning of the growth period, while 1 mM cadaverine, the product of the reaction, reversed this inhibitory effect when added to the culture medium. When difluoromethyllysine was added during the logarithmic growth phase of Mycoplasma, it inhibited the increase of the growth; 1 mM cadaverine again partially reversed this inhibitory action.

Arginine↗
PubMed1984

Resection followed by vascularized bone autograft in patients with possible recurrence of malignant bone tumors after conservative treatment.

In conservative treatment of malignant bone tumors, assessment of the local condition is difficult. The radiological changes seen in the irradiated tumor and the frequent occurrence of pathological fractures at this site may give rise to the fear that the tumor has relapsed. Resection of the whole of the involved bone is the best way to assure adequate local control but the extent of the bone defect and the bad local conditions secondary to irradiation make reconstruction hazardous. In two patients (one with Ewing's sarcoma of the femur and one with osteogenic sarcoma of the humerus) the authors used a free, vascularized fibular graft for the reconstruction having obtained consolidation of the limb after resection of the irradiated tumor, with preservation of its function. The encouraging results obtained have suggested a conservative attitude as primary treatment of specific malignant bone tumors.

Adolescent↗