Membrane effects of thyrotropin-releasing hormone and estrogen shown by intracellular recording from pituitary cells.

The effects of thyrotropin-releasing hormone and 17 beta-estradiol on the electrical membrane properties of a prolactin-secretin pituitary cell line (GH3/B6) were studied with intracellular microelectrode recordings. Of the cells tested, 50 percent were excitable and displayed calcium-dependent action potentials when depolarized. When injected directly on the membrane of an excitable cell, thyrotropin-releasing hormone and 17 beta-estradiol induced action potentials within 1 minute. The spiking activity was preceded by a progressive increase of the input resistance without any detectable change in the resting membrane polarization. The results reveal a rapid effect of both substances on the membrane of GH3/B6 cells. In the case of thyrotropin-releasing hormone, which has both a short-term effect on release of prolactin and a long-term effect on its synthesis, the induced electrical activity may be associated with the stimulation of prolactin production. The physiological implication of 17 beta-estradiol-induced, calcium-dependent spiking activity remains to be elucidated.

An in vitro study of the susceptibility of cells from a meningioma of human origin for measles virus.

A cell culture from a meningioma of human origin was found permissive for the Edmonston strain of measles virus. Virus was isolated from the supernatant of infected cell sheet as soon as 48 hr post-inoculation. Cytopathic effect, observed by light microscopy, exhibited syncitia plus intracytoplasmic and intranuclear inclusions. Electron microscopy enabled viral nucleocapsids to be observed first in the cytoplasm and secondly within the nucleus of infected cells.

Differences in early ultrastructural aspects of the replication of measles and subacute sclerosing panencephalitis viruses in a cell culture from a human astrocytoma.

Monolayer cultures from a human astrocytoma were infected with small amounts of Mantooth Subacute Sclerosing Panencephalitis (SSPE) and Edmonston measles viruses. The infected cells were studied with an electron microscope 48 hours and 96 hours post-inoculation (PI). By 48 hours PI, both viruses produced syncytia and cytoplasmic inclusions of granular nucleocapsids 20 to 25 nm in diameter which did not differ in appearance. With the Edmonston measles virus granular nucleocapsids assembled into budding particles were found just under the cell membrane while nucleocapsids of Mantooth SSPE virus spared the area under the cell membrane and were not incorporated into budding particles. Inclusions of smooth nucleocapsids, 15 nm in diameter, could be seen within the nuclei of Mantooth SSPE virus infected cells 96 hours PI; such nuclear inclusions were not found in the Edmonston measles virus infected cells. These results are compared with those obtained in other cell systems and are discussed with respect to recent findings in the field of SSPE.

Serological evidence of human infection with the paramyxovirus Yucaipa in Senegal, West Africa.

Sera from 353 people resident in Dakar, Senegal, West Africa, were tested for hemagglutination-inhibiting antibodies against the avian paramyxovirus Yucaipa. Antibodies were demonstrated in five sera (1.4%), providing new evidence that this virus may infect humans.

Cholinergic neurons of fetal rat telencephalon in aggregating cell culture respond to NGF as well as to protein kinase C-activating tumor promoters.

Serum-free aggregating cell cultures of fetal rat telencephalon treated with the potent tumor promoter phorbol 12-myristate 13-acetate (PMA) showed a dose-dependent, persistent stimulation of the enzymes choline acetyltransferase (ChAT), glutamic acid decarboxylase and glutamine synthetase. After elimination of the proliferating cells by treatment of the cultures with Ara-C (0.4 microM) only the cholinergic marker enzyme, ChAT, could be stimulated by tumor promoters. The non-promoting phorbol ester, 4 alpha-phorbol 12,13-didecanoate proved to be inactive in these cultures, whereas the potent non-phorbol tumor promoter, mezerein, produced an even greater stimulatory effect than PMA. Since PMA and mezerein are potent and specific activators of protein kinase C, the present results suggest a role for this second messenger in the development of cholinergic telencephalon neurons. Stimulation of ChAT required prolonged exposure (48 h) of the cultures to PMA and the responsiveness of the cholinergic neurons to the tumor promoters decreased with progressive cellular maturation. The cholinergic telencephalon neurons showed the same pattern of responsiveness for tumor promoters as for nerve growth factor (NGF). However, the combined treatment with NGF and either PMA or mezerein produced an additive stimulatory effect, suggesting somewhat different mechanisms of action.

Studies on bovine Breda virus.

Diarrheic feces from 21 calves were examined by electron microscopy and 16 contained particles morphologically similar to those of Breda virus. The particles were spherical or elongated, 60-270 nm in greatest dimension and had surface spikes 9-13 nm long. Convalescent serum from a human patient with Breda virus-associated diarrhea reacted with one of the bovine viruses by immune electron microscopy, suggesting a serological resemblance between human and bovine Breda-like viruses. Immune electron-microscopy and immunofluorescence demonstrated that isolates of bovine Breda virus from the U.S.A. were related to the French virus. One of the viruses had a density in sucrose solution of 1.16, similar to the value for Berne virus.

[Comparative study of 2 commercial tests for the detection of HIV-1 antigens in blood and cerebrospinal fluid using immunoenzymology]. / Etude comparative de deux trousses commerciales pour la recherche de l'antigène HIV I en immunoenzymologie (EIA) dans le sérum et le liquide céphalorachidien.

The authors have carried out, on 150 sera of patients seropositive for the human immunodeficiency virus type I (HIV I) and 11 cerebrospinal fluid of which 5 were patient infected by the HIV I, a comparative study of two commercial tests for the detection of HIV I antigen (Diagnostic Pasteur and Abbott laboratories). A much greater sensitivity was obtained with the specificity being practically identical for the sera with the two tests (100% with Abbott laboratories test, 96.11% with the diagnostic Pasteur test). 4 sera appeared "false negatives" with the Abbott Laboratories test; their optical density was situated between 80 and 100 p. cent of the cut-off level value, whereas that of the "real" negatives was situated between 30 and 60 p. cent of the cut-off level value. 10 of the 11 cerebrospinal fluids appeared false positive with the Diagnostic Pasteur. This seems to be connected with an insufficiency of saturation of protein receptors in the wells. The Diagnostic Pasteur test is not adapted for the detection of HIV I antigen in the body fluids with a weak protein concentration. Contrary to the results obtained with the Encavor test (Abbott laboratories) the analysis in western-blot does not show an inverse prevalence of anti p24 GAG antibodies with regard to antigen HIV I in seropositive patients. On the other hand, the statistical analysis of the positive HIV I sera which are at the same time antigen HIV I positive and antibodies HIV I positive suggests an earlier disappearance of anti p17 GAG antibodies than of anti p24 GAG antibodies.

[Clinical, biological and developmental aspects of cytomegalovirus infection in immunocompetent patients: apropos of 34 hospitalized patients]. / Aspects cliniques, biologiques et évolutifs de l'infection à cytomégalovirus chez le sujet immunocompétent: à propos de 34 patients hospitalisés.

We reviewed the thirty cases of cytomegalovirus infections with occurred in previously healthy patients, hospitalised for fever from 1981 to 1992. Pregnant women, transplant recipients, HIV infected persons and all immunocompromised subjects were excluded. We observed 34 cases (18 women, 16 men) whose mean age was 34 years (17 to 79). Fever appeared progressively (73%), persisted more than 15 days (87%) and was well tolerated. The main functional symptoms were headaches, myalgia (53%), profuse sweat (50%), abdominal pain, diarrhea, recent loss of weight, dry cough (51%). Splenomegaly was present in 24% of the cases. Chest X ray was always normal. Differential blood count was always inverse and an authentic mononucleosis syndrome was present in 91%: it appeared mainly 13 days after onset of symptoms. Hepatic abnormalities were nearly constant, especially cytolytic (97%) (transaminases three or four times upper the normal limit) but also cholestatic (62%). Thrombopenia has been noticed once (48,000/mm3). Serological diagnosis was confirmed with Elisa test (anti CMV Ig M: 30 cases) or complement fixation test (seroconversion: one, significant increase of the titers: two). CMV viremia, studied in seven patients, was positive in three. Spontaneous or treated (NSAI in 30%) outcome was nearly always favourable (97%). Two patients presented severe complications: meningo encephalitis and spleen rupture. CMV infection in previously healthy patients has to be suspected, without waiting for the mononucleosis syndrome, in view of a prolonged, well tolerated febrile illness, without pharyngitis, associated with hyperlymphocytosis and mild cytolysis. A careful follow-up is needed to detect the rare but severe complications.

[Viral gastroenteritis]. / Les gastroenterites virales.

Many virus are able to induce gastroenteritis, especially in young children with immunological or nutritional defects. The most frequently observed, using ELISA, are Rotavirus. The others : Norwalk agent, Coronavirus, Breda virus, are identified using electron microscope. Using symptomatic therapy, prognosis is related to precocious hydratation.

[Morphological study of paramyxovirus Yucaipa]. / Etude morphologique de paramyxovirus Yucaipa.

Paramyxovirus Yucaipa exhibits a dramatic polymorphism. One can observe round particles, 250 nm in diameter, and numerous filamentous forms, some of which are 1800 nm long.

A high-precision and large-capacity laser biophotometer.

A new type of biophotometer is described. Very precise and reproducible measurements of bacterial concentration can be performed at 3-s intervals for each of 32 simultaneously developing bacterial cultures. The large number of results is handled with modern data acquisition and computer-processing techniques.

Gianotti-Crosti syndrome: a study of 26 cases.

We have studied 26 patients presenting with a symmetrical papular or papulovesicular acrolocated eruption of more than 10 days duration. Mean age at onset was 2 years (range 10 months to 5.75 years). Lymphadenopathy was noted in eight cases, and hepatomegaly in one case. In 12 cases, histopathology and direct immunofluorescence were non-contributory. Cytolytic hepatitis occurred in one case and was associated with HBs antigenemia. A history of recent immunization was given in two cases. There was serological evidence of recent Epstein-Barr virus infection in seven out of 13 cases tested. Coxsackie B viruses were isolated from three patients, and cytomegalovirus was probably associated with the syndrome in one case. We conclude that the Gianotti-Crosti syndrome is not rare in France, and that non-hepatitis B virus (HBV)-associated cases are more frequent than the classical HBV-associated papular acrodermatitis of childhood.

[Serological study of the occurrence of Herpesviridae in French Guyana]. / Etude sérologique de la prévalence des Herpesviridae en Guyane française.

300 samples of serum (in seven age-groups) from the "creole" population of french Guiana were tested for antibodies to the four human herpesviruses (HSV, VZV, CMV and EBV). Results show the higher prevalence of CMV and EBV in early childhood, HSV primary infection appears to take place earlier in life than in temperate and developed countries, but later than in other tropical countries. The pattern of VZV epidemiology in french Guiana is consistent with what is known in tropical countries: varicella is also a disease of adolescents and young adults. CMV appears to be more prevalent in women than in men between 21 and 40.

Dexamethasone stimulates the biochemical differentiation of fetal forebrain cells in reaggregating cultures.

The influence of dexamethasone on the development of neurons and oligodendrocytes was studied in serum-free, aggregating rat brain cell cultures. Synaptogenesis and myelination occur in this culture system. The concentration of myelin basic protein and the activity of 2',3'-cyclic nucleotide 3'-phosphodiesterase were used as oligodendroglia and myelin markers. Choline acetyltransferase and acetylcholinesterase served as neuronal markers, glutamine synthetase reflected astrocyte differentiation, while ornithine decarboxylase served as a general marker for cell growth and maturation. This study showed that dexamethasone stimulated the differentiation of cholinergic neurons and astrocytes. The effect of dexamethasone on oligodendroglial differentiation and myelination depended on the stage of development: during the early phase of myelination dexamethasone had a stimulatory effect, whereas at a later stage it showed a significant inhibition.