Sequence of the penicillin-binding protein 2-encoding gene (penA) of Neisseria perflava/sicca.

The nucleotide sequence of the transpeptidase domain (Tp) of the penicillin (Pn)-binding protein 2-encoding gene (penA) from two Pn-sensitive (PnS) and two Pn-resistant (PnR) strains of Neisseria perflava/sicca, has been determined. The sequences from PnS strains, although displaying high homology with those PnS strains from other Neisseria species, also showed several interesting modifications suggesting that these isolates might represent intermediates in the mutational development of PnR in N. perflava/sicca.

[Giant cholesterol cysts of the petrous apex]. / Les kystes à cholestérine géants de l'apex pétreux.

In connection with their two own cases, the authors deal about the giant cholesterol cysts of the petrous apex. The lesions which are to be differentiated from epidermoid cysts are cholesterol granulomas. Their petrous apex location explains their characteristic large appearance. As each cholesterol granuloma, they occur when a bony cell is obstructed. This chronic obstruction induces mucosal edema then bleedings which lead to the formation and, by the lack of drainage, to the accumulation of cholesterol crystals. These crystals initiate a non specific reaction to foreign bodies, a granuloma, which also can bleed. Thus, a continuous cycle perpetuates the growth of the lesion. This lesion, when it is localized in the petrous apex, can reach a big size before the appearance of some signs. Usually, these are otologic (sensorineural hearing loss, tinnitus, vertigo) and/or cranial nerve palsies (V, VI, VII). C.T. scan (well defined, sharply marginated bony expansible lesion with isodense to the brain central part) and M.R.I. (central region of increased intensity on both T1 and T2 weighted images and peripheral rim of markedly decreased signal intensity in all instances) features are characteristic enough to allow diagnose with other petrous apex lesions (cholesteatoma, mucocele, epithelial cyst, histiocytosis X, ...). Surgical treatment must try to evacuate and to aerate the cavity or perhaps to obliterate it with fatty pieces in order to prevent the recurrence.

Value of MRI in the morphological evaluation of tumors of the third ventricle.

The detection or suspicion of a tumoral expansive process in the third ventricule is usually performed by MRI. The contribution of MRI to the diagnosis is unquestionable in view of its accuracy in the topographical characterization of these lesions and in the detection of small formations. The great histological variety of tumours in that region may result in different treatments which can be associated. MRI, therefore, plays an important role in pretherapeutic morphological evaluation. Fifteen patients with tumour of the third ventricle were examined by MRI before treatment. The results of these examinations were compared with the pathological data and the therapeutic procedures: ventricular shunting, stereotactic needle biopsy, radio- or chemotherapy and surgery. MRI cannot provide a formal histological characterization, but it can individualise some categories of tumours, give details on the walls of the third ventricle (notably in the case of bifocal pineal and suprassellar lesions), visualize the paths of CSF flow and predict the need for cisternoventriculostomy, and detect venous structures in the vicinity of the great cerebral vein which might result in post-biopsy and post-surgery complications.

A new approach of brain tumors: the cytogenetic study.

Cytogenetic studies of brain tumors in adults have made it possible to determine specific chromosomal abnormalities and to detect a high incidence of gene amplification related to these abnormalities. Data from the literature and our own results show frequent numerical deviations in glioblastomas, such as gain of chromosome 7, but also 19, 20 and X, loss of certain chromosomes: monosomies 6, 14 and 22. Most of the structural abnormalities are deletions involving the chromosomal regions 1p, 6q, 7q and 9p, and the presence of double-minutes (DMs), the latter being the chromosomal expression of EGFR gene amplification. Cytogenetic analysis of meningiomas has shown that some of them have monosomy 22 alone while others have additional abnormalities. Antioncogenes probably play a part in these tumors. Their identification will explain the neuro-oncogenesis process and perhaps open a new route for the treatment of brain tumors.

Oligodendrogliomas.

Oligodendrogliomas are tumours developed from oligodendrocytes. They may be pure or associated with astrocyte proliferation. They are usually benign, but their malignancy grade is varied. These tumours affect middle-aged adults and are characterized by their slow growth and their fairly suggestive neuroradiological features which are those of a large, calcified, poorly enhanced, peripheral frontal lesion. Computerized tomography and magnetic resonance imaging are suitable complementary methods to characterize the tumour and evaluate its extension.

Primary and secondary lymphomas of the brain: an MRI study.

Three types of lymphoma of the central nervous system are known: primary non-Hodgkin's malignant lymphoma (NHML), secondary NHML and neurological lesions of Hodgkin's disease. NHML's are rare tumours, often associated with immunodeficiency and presenting predominantly as neuropsychological disorders. In this study 8 patients were explored by CT and MRI, with pathological confirmation. None of our patients had AIDS. The most typical neuroradiological image of this type of tumour is that of a large and intensely contrast-enhanced tumoral mass which is often multifocal and periventricular with infiltration of the subarachnoidal spaces and leptomeninges. Mass effect and perifocal oedema are less pronounced than expected with tumours of that size. NHML's may totally regress under corticosteroid therapy. This tumour of obscure aetiology must be recognized as it is now increasingly frequent.

Magnetic resonance imaging in gangliogliomas and gangliocytomas of the nervous system.

Gangliogliomas and gangliocytomas are rare and benign neuronal tumors which affect young subjects. This study concerns 3 cases of ganglioglioma and 3 cases of gangliocytoma explored by CT and MRI and confirmed by pathological examination. The most typical CT image was that of an often calcified contrast-enhanced cystic tumor. At MRI, each tumor emitted a low-intensity signal on T1-weighted sequences and a high-intensity signal on T2-weighted sequences. Contrast enhancement after gadolinium injection was frequent. Neuroradiology is not specific, and these tumors are usually diagnosed at pathology. However, the diagnosis may be considered in young patients with a history of old, drug-resistant partial epilepsy and having a contrast-enhanced, calcified cystic lesion in the temporal lobe or the cerebellum.

Supratentorial ependymomas. Neuroradiological study.

Ependymoma is a rare tumour developed from ependymal cells and belonging to the group of neuroglial tumours. It may be located in any part of the central nervous system, but shows a preference for the ventricular cavities. Neuroradiology is not specific. CT shows a frequently large, calcified and cystic lesion of varied density and strongly contrast-enhanced. The signal emitted at MRI is often heterogeneous. Treatment consists of surgery combined with radiotherapy. Prognosis is poor owing to the difficulty of surgical excision and to the possibility of CSF grafts.

[Slowly progressive myopathy with accumulation of tubular aggregates]. / Myopathie lentement progressive avec accumulation d'agrégats tubulaires.

Slowly progressive myopathy with tubular aggregates is rare and dominantly or recessively inherited. Three sporadic cases are reported in the present study occurring in 2 men and 1 young woman. All patients had proximal limb weakness without severe atrophy. They also complained of exercise-induced stiffening and cramps of their leg muscles. In 1 case severe cardiomyopathy caused unfavorable clinical course and death. Serum creatine kinase activity was normal and electromyogram showed only slight myopathic changes. Tubular aggregates were found to be the sale morphological abnormality. They were present in type II fibres in 1 case and in type I and type II fibres in the others. An immunocytological study with a polyclonal antibody against Ca2+ SR-ATPase showed positivity of the tubular aggregates with this antibody. A quantitative analysis (SAMBA 2000 alcatel TITN) was carried out on frozen sections stained for calcium. It showed a lower calcium content in tubular aggregates than in other part of the fibre. Slowly progressive myopathy with tubular aggregates may be distinguished from other diseases where tubular aggregates are the sale structural change, such as myopathies with myasthenic features and some neuromuscular diseases with exercise intolerance without progressive course. Usually, tubular aggregates are not a specific finding; they have been described in various disorders in association with other structural changes.

Infratentorial ependymomas of childhood. Correlation between histological features, immunohistological phenotype, silver nucleolar organizer region staining values and post-operative survival in 16 cases.

We have examined pathological criteria in 16 cases of infratentorial ependymomas of childhood using a conventional histological approach, with immunohistochemistry and silver nucleolar organizer region staining (AgNORs). We have found that some of these criteria are of prognostic value. The following histological features were evaluated in each case: cellular density, cellular or nuclear pleiomorphism, mitosis, focal necrosis, endothelial proliferation and complete loss of differentiation. The expression of the following antigens was also studied: epithelial membrane antigen (EMA), human natural killer (HNK1), glial fibrillary acidic protein (GFAP) and vimentin. Only three histological criteria have been retained as indicative of bad prognosis, i.e., high mitotic index, a large amount of necrosis and complete loss of differentiation. These criteria distinguish ependymomas from anaplastic ependymomas. GFAP was expressed in all tumors while other antigens were more variable. In addition tumors expressing large amounts of GFAP were statistically associated with a better prognosis. Increased vimentin expression associated with a decrease of GFAP immunoreactivity correlated with anaplasia and short survival. EMA was not directly correlated with postoperative survival but may be considered as a further prognostic factor. Finally AgNORs values were not statistically correlated with postoperative survival.

Thyroid hormone and circadian regulation of the binding activity of a liver-specific protein associated with the 5'-flanking region of the S14 gene.

Recent studies have described a DNase I hypersensitive site in the 5'-flanking region of the rat hepatic S14 gene that is closely associated with its expression. A 111-base pair subfragment (-389 to -279) of this region interacts specifically in a gel shift assay with a protein present in hepatic nuclear protein extracts. This protein, designated P1, was not present in extracts of other tissues, even those in which the gene is expressed and hormonally regulated. The binding activity of P1 is exceedingly low in extracts from hypothyroid rats and is markedly increased by administration of thyroid hormone. However, the slow accumulation of P1 after thyroid hormone administration indicates that increased levels of P1 are not necessary for the acute hormonal induction of S14 gene expression. The level of P1 binding activity increases in the evening, synchronous with circadian variation of hepatic mRNA S14. Since neither P1 binding activity nor circadian variation in mRNA-S14 levels are observed in the other tissues expressing the S14 gene, P1 may function to modulate the circadian rhythm observed in hepatic S14 gene expression. DNase I footprinting analysis revealed that P1 binds to a defined nucleotide sequence, 5'-AAAAGAGCTATTGATTGCCTGCA-3', located between -310 and -288 in the S14 gene.

Interaction of dietary carbohydrate and glucagon in regulation of rat hepatic messenger ribonucleic acid S14 expression: role of circadian factors and 3',5'-cyclic adenosine monophosphate.

The mRNA of the rat hepatic S14 gene accumulates rapidly after administration of T3 and carbohydrate, making it an excellent model for studies of the effects of dietary and hormonal stimuli at the hepatocellular level. We undertook studies to assess circadian changes in responsivity of this sequence to intragastric sucrose administration combined with insulin injection, and evaluated the capacity of glucagon to reverse these effects. As in the case of T3, the response of mRNA-S14 to carbohydrate in the morning was brisk whereas there was no significant increment when the stimulus was applied in the evening. In confirmation of previous studies, glucagon markedly lowered levels of mRNA-S14 in the evening but exerted no effect in the morning. These results support the concept that the rate of hepatic production of mRNA-S14 in unmanipulated rats is maximal in the evening, thus allowing no further induction by carbohydrate or T3 but permitting reduction by glucagon. Conversely, the rate of production is minimal in the morning, permitting induction by carbohydrate or T3 but allowing no further reduction by glucagon. A major difference between the effects of carbohydrate and those of T3 was the observed failure of carbohydrate to reverse the effect of glucagon in the evening. The effect of glucagon was stimulated by (Bu)2cAMP, and this was reversed by T3. However, T3 did not modify the glucagon-induced increase in hepatic cAMP levels. We therefore conclude that the capacity of T3 to abolish the glucagon effect is mediated at a step distal to the generation of cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)