In vitro effect of aflatoxin B1 on the transcriptional activity of DNA template, chromatin and soluble DNA-dependent RNA polymerases in buffalo liver.

The effect of aflatoxin B1 on the DNA template and DNA-dependent RNA polymerases in buffalo liver was studied. Aflatoxin B1 inhibited both Mg2+- and Mn2+-activated RNA polymerases in a dose-dependent manner. At 10 micrograms the inhibition of both enzymes was almost complete. The inhibitory effect on the solubilized enzymes was higher than the chromatin-bound, suggesting a direct effect at the enzyme level. On the other hand, incubating DNA or deoxyribonucleoprotein (DNP) with 2 micrograms aflatoxin reduces its transcriptional capacity with a greater effect on the Mg2+-activated RNA polymerase than the Mn2+-activated enzyme. These results suggest that aflatoxin B1 inhibits in vitro transcription in buffalo liver at both enzyme and template levels.

Isolation, purification and characterization of enzyme(s) responsible for conversion of sterigmatocystin to aflatoxin B1.

The cell-free extract prepared from Aspergillus flavus ATCC 5517/A 228 showed activity in converting sterigmatocystin to aflatoxin B1. The extract was purified on Ultrogel AcA-54 and resulted in ten protein peaks, one of which (peak VI) showed activity in sterigmatocystin conversion. The protein in this peak gave one protein band using polyacrylamide gel (PAG)-disc electrophoresis. For further purification, protein(s) in peak VI were applied on DEAE-Sephadex A-50 and two protein peaks were detected. Only one peak showed enzyme activity which showed homogeneity as one band on PAGE and sodium dodecyl sulphate (SDS)-PAGE. The optimum temperature for the enzyme activity was 28 degrees C and the optimum pH was 8. The maximum conversion resulted from the action of 0.6 mg enzyme protein on 48 X 10(-8) mol sterigmatocystin. Zn2+, Co2+ and Mn2+ enhanced the enzyme activity, while ethylenediaminetetraacetic acid, parahydroxymercuric benzoate and phenylmethylsulphonic fluoride inhibited the enzyme activity in a dose-dependent manner. Amino-acid analysis showed the presence of 22 amino acids, three of which are unknown. The enzyme has a molecular weight of 64,000 daltons (by gel filtration) and 70,000 daltons (by SDS-PAGE).

[Hypoglycorrhachia and postpartum aseptic cerebral thrombophlebitis with meningeal hemorrhage]. / Hypoglycorachie et thrombophlébite cérébrale aseptique du post-partum avec hémorragie méningée.

A 42-year-old woman had a puerperal aseptic cerebral thrombophlebitis with repeated episodes of subarachnoid hemorrhage. Cerebrospinal fluid studies revealed a delayed, severe and lasting low sugar and high protein levels. The possible mechanisms of low sugar levels are discussed.

[Acquired cerebral toxoplasmosis in adults. Clinical and neuropathologic study]. / Toxoplasmose cérébrale acquise de l'adulte. Etude clinique et neuropathologique.

Two cases of acquired cerebral toxoplasmosis in adults are reported. In the first case no subjacent disease was found, and the neurological signs were of a meningo-encephalitic type with disorders of consciousness and a C.S.F. cellular reaction. A second case was observed in the course of the treatment of Waldenström disease by chloraminophene. The neurological signs were bifocal, and the C.S.F. showed a moderate increase of protein. In both cases C.T. scan showed contrast enhanced and hypodense areas. In the first case the enhancement was heterogenous and the hypodense area occupied the whole right hemisphere. The second case showed two ring enhancements in the left frontal and the right occipital regions. A cerebral biopsy was performed in both cases but no parasite was found. The diagnosis was presumed to be malignant lymphoma or encephalitis in the first case, glioblastoma in the second. No specific treatment was administered and the patients died within a few weeks. The complete pathological study by light and electron microscopy showed free and cystic forms of Toxoplasma Gondii. The results of the neuropathological examination and the thorough study of the biopsy specimens were compared to the pathological findings in the literature. The particular character of the necrosis and the inflammatory encephalitic reaction in the absence of the parasite may suggest the diagnosis when the clinical, biological and radiological data are compared.

Cranial computed tomography in the phakomatoses.

The authors present the CT findings in their personal series of 77 cases of neurofibromatosis, 34 cases of tuberous sclerosis, and 16 cases of Sturge-Weber disease. These findings are extensively illustrated and compared with those reported in the literature.

Status spongiosus in the course of treatment of malignant gliomas.

Two cases of fatal encephalopathy which appeared in the course of treatment of malignant gliomas are described. CT scan showed diffuse, low density, non-enhanced lesions of the white matter. Pathological findings showed that the CT scan aspects corresponded to status spongiosus without demyelination. We were unable to find similar reports in the literature.

[Pseudo-tumoral human African trypanosomiasis due to Trypanosoma gambiense. Clinical and tomodensitometry study (author's transl)]. / Formes pseudo-tumorales de la trypanosomiase africaine à Trypanosoma gambiense. Etude clinique et tomodensitométrique.

The authors report an observation of african trypanosomiasis due to Trypanosoma Gambiense, clinical signs included massive and progressive hemiplegia, papillary edema and vascular shift from median line at arteriography. These pseudo tumoral clinical features are unusual in this disease. Asymetrical heterogenous hypodensities of the centrum semioval are dominant in the initial CT scanner aspect. The confrontation of CT scanner images to the clinical and evolutive data suggests the presence of associated cerebral edema and demyelination. With treatment, hypodensities were regressing while images of subcortical atrophy appeared. Lastly, in spite of severe general signs and the importance of neurological deficit, arsenical treatment associated with high doses of corticotherapy lead to a rapid improvement.

[Reversible dialytic encephalopathy after interruption of aluminium intake. 6 cases (author's transl)]. / Encéphalopathie réversible des dialysés après arrêt de l'apport d'aluminium. 6 cas.

The cases presented with psychic troubles and repeated somnolence episodes accompanied by dysarthria in 5 cases, myoclonic jerks in 4 cases and epileptic seizures in 1 case. In all cases the EEG was disturbed. It showed symetrical, paroxystic, bilateral, monomorph slow activity with more or less frequent paroxysms. The average serum aluminium level was at 407 microgram/l in the acute phase, at 161 microgram/l in the remission phase and at 123 microgram/l three months later. After interruption of oral and dialytic aluminium intake the remission is maintained. However in 2 cases the transitory readministration of aluminium gel was followed by reversible recurrency. The role of both aluminium gel and dialysate aluminium as the origin of encephalopathy is discussed.

Malignant gliomas treated after surgery by combination chemotherapy and delayed irradiation. Part I: Analysis of results.

Forty-six patients with gliomas were introduced after surgery into a therapeutic programme of six cycles of combination chemotherapy with VM26 and CCNU, followed by delayed irradiation six months after surgery with an average dose of 5,800 rads. After irradiation the same preradiation chemotherapy was readministered for an average of four cycles. The results were compared to those from another group of 28 patients treated only by the same chemotherapy (CRC and C groups sucessively). Twelve patients (26%) died before irradiation in the CRC group, six patients (13%) had recurrences at the time of irradiation, and 28 patients (61%) had no clinical or radiological signs of recurrence at the time of irradiation. For the total of treated patients the median survival after surgery was 17 months, and 46% of the patients were surviving at 18 months. The percentage of survivors at 18 months was significantly more elevated in the group treated by combination chemotherapy and delayed irradiation than in a control group treated by the same combination chemotherapy alone. This result suggests that in approximately 50% of cases combination chemotherapy after surgery, and delayed irradiation six months after surgery, cumulated their effects on survival time.

Malignant gliomas treated after surgery by combination chemotherapy and delayed radiation therapy. Part II. Tolerance to irradiation after chemotherapy.

34 patients operated on for malignant gliomas were successively treated by combination chemotherapy with VM26 and CCNU and conventional radiation therapy with an average dosage of 5,800 Rads, six months after surgery. The general and haematological tolerance of delayed irradiation after chemotherapy was satisfactory. Twelve patients developed neurological complications during or after irradiation. The complications were early in 10 cases, and delayed in 2. They were probably due to tumour growth in five cases, and secondary to irradiation in seven. In four of the seven cases the preradiation chemotherapy seemed to potentiate the radiation effect on the central nervous system.