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J Laporte

Publications and source records attributed to J Laporte.

At least 91 records · Page 5Linked to original sources
PubMed1987

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.

Animals↗
PubMed1987

[Reciprocal changes in the ST segment in acute inferior myocardial infarction. Value of delay in appearance].

The significance of a "reciprocal" ST depression (ST(-)) in the acute phase of myocardial infarction remains controverted. This may be due to ST(-) not having the same determinants when studied at an early stage (less than 6 hours) or later (greater than 6 hours). The purpose of this study was to find out whether "reciprocal" ST(-) correlates with the same parameters when measured on very early ECG's (before 6 hours) or at a distance from the onset of infarction. The parameters concerned are coronary lesions, extent of the infarction and left ventricular function. ECG was performed in 46 patients with inferior infarct aged from 26 to 70 years (mean 50.8 +/- 9.2 years) between 2-6 h, 6-12 h, 12-24 h and 24-48 h from the beginning of pain. The sum of ST(-) on V1V2V2V4 (V1-4), D1aV1V1 to V6 and L1aV1V5V6, and the sum of ST elevation on L2L3aVf were measured at each period of time. The extent of global and anterior territory hypokinesia, the ejection fraction and the left coronary impairment were evaluated between the 2nd and 4th weeks. At 2-6 hours (a) the sum of ST(-) was greater (though not significantly), and the sum of ST elevation on L2L3aVf was significantly greater (p less than 0.001) when the left anterior descending artery (LAD) was not involved than when it was involved; (b) there was no difference between patients with and without ST depression (on all lead groups) in the degree of left ventricular hypokinesia and ejection fraction value.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Influence of the autonomic nervous system on the normal and pathological atrioventricular node].

The finding of a first-degree atrioventricular block suggests various mechanisms of atrioventricular (AV) node alteration: organic lesion, or functional disorder related to the autonomic nervous system, or a combination of both. The influence of the autonomic nervous system was evaluated by administration of Jose's regimen, i.e. intravenous injection of propranolol 0.2 mg/kg bodyweight and atropine 0.04 mg/kg bodyweight. This regimen was tested in 101 patients divided into two groups: 38 subjects with normal sinus node and AV node acting as controls, and 63 patients with abnormal AV node. In the control group the autonomic nervous system had no influence on atrio-hisian (AH) conduction time or on the effective refractory period of the AV node under an imposed cycle of 600 ms. Wenckebach's period significantly (p less than 0.01) increased from 352 +/- 40 ms to 376 +/- 47 ms. Parasympathetic activity was found to predominate in the sinus node. In the group with pathological AV node three types of response were observed after pharmacological inhibition of the autonomic nervous system: (a) improvement or even complete normalization (40%) of AV node conduction ability (AH, Wenckebach's period) suggesting vagal hyperactivity, as also found in the sinus node; (b) changes similar to those observed in the control group and reflecting the same behaviour of the autonomic nervous system, and (c) increase in AH conduction abnormalities reflecting the presence of a sympathetic overdrive tending to minimize the consequences of an atrioventricular organic lesion. This sympathetic overdrive was also found to be present in the sinus node.

Adolescent↗
PubMed1986

Prevalence of various enteropathogens in the feces of diarrheic and healthy calves.

The presence of various enteropathogens was examined in the feces of homebred dairy calves reared in a restricted geographical area of France (North West of County of Indre-et-Loire) during winter 1983-1984. Two distinct surveys were carried on: a case-control study including 32 diarrheic calves and 21 healthy calves bred in 53 different farms; and a separate study on nine diarrheic calves in another farm. The following infectious agents were looked for, by specific methods of detection: Escherichia coli K99 and E. coli lethal for mice, Salmonella species, Yersinia enterocolitica, Campylobacter jejuni, enterotoxigenic Clostridium perfringens, Chlamydia psittaci, rotaviruses, coronaviruses, Cryptosporidium. In the case-control survey, no enterotoxigenic E. coli (K99+) was detected in either group of calves. Four agents were more often detected in diarrheic calves than in healthy calves, i.e. rotavirus (12/32 vs 1/21), lethal E. coli (6/32 vs 1/21), Cryptosporidium (2/32 vs 0/21) and Salmonella typhimurium (1/32 vs 0/21). One at least of these four agents was present in 16 diarrheic calves (50%) vs only 2 healthy calves (10%) (P less than 0.01). On the other hand, the occurrence of Campylobacter jejuni and of C. perfringens, enterotoxin was similar in both groups of calves, accounting respectively for about 20% and 10% of total calves. Moreover, coronavirus-like particles were significatively associated with healthy calves (7/32 vs 11/21; P less than 0.05). In the other study, all the main categories of enteropathogens were detected throughout the period of observation in the same farm with the exception of enterotoxigenic E. coli. But each calf taken individually was rarely shedding more than two agents at a time. In addition, specific antibodies against C. perfringens enterotoxin, as tested in an ELISA test, were present in the serum of all the calves examined in both surveys. This study confirms the primary role of rotavirus and Cryptosporidium as agents of diarrhea in calves under three weeks. It also suggests the possible participation of E. coli strains that are lethal for mice and underlines the potential hazard for human health of bovine reservoirs of Campylobacter jejuni and enterotoxigenic C. perfringens.

Animals↗
PubMed1986

[Corrected transposition of the great vessels in aged adults. Apropos of 2 patients aged 72 and 80].

The authors report two unusual new cases of corrected transposition of the great arteries diagnosed in patients 72 and 80 years of age respectively, presenting with symptoms of cardiac failure of recent onset. Both patients had mild or moderate regurgitation of the systemic atrio-ventricular valve, associated in one case with aortic regurgitation. This association would appear to be fortuitous although already reported in six occasions. The diagnosis was made by echocardiography and confirmed by catheterisation in one case, and by digitised intravenous angiography in the other. These cases are of interest for three reasons: They are very rare: there have been only 20 comparable cases reported in patients over 40 years of age, the eldest being 73. This is probably explained by the high frequency of associated malformations. They illustrate the decisive role of echocardiography in the diagnosis of congenital heart disease, even in the adult. They constitute a "natural experimental model" of a right ventricle submitted to systemic pressures and tend to show that, in the absence of other abnormalities giving rise to an additional pressure or volume overload, the right ventricle is capable of long term adaptation to this situation. These observations indicate a favourable long-term prognosis for children who have undergone "corrective" surgery at atrial level for simple transposition and in whom the right ventricle is required to assume the function of the systemic ventricle for the rest of their life.

Aged↗
PubMed1983

Utilization of monoclonal antibodies for antigenic characterization of coronaviruses.

Hybrid cells secreting monoclonal antibodies against Bovine Enteric Coronavirus (BECV strain G110) were obtained by fusion between SP2/O myeloma cells and splenocytes of mice hyperimmunized with purified virus. Specificity of 8 from the 12 monoclonal antibodies was established to be anti-GP105 by immunochemical staining of viral polypeptides and by immunoprecipitation of radioactive-labelled viral proteins. The reactivity of three BECV isolates (strain G110, F15 and NCDCV) with the different monoclonal antibodies was studied by indirect immunofluorescence (IIF), ELISA, hemagglutination-inhibition and seroneutralization. G110 and F15 interacted in a similar manner with the monoclonal antibodies, but NCDCV failed to react with A9 monoclonal antibody. IIF test allowed us to detect another difference between U.K. BECV isolate and other BECV, in that the U.K. isolate did not react with F7 monoclonal antibody. No differences could be seen by IIF in the reactivity of Danish BECV isolate, Human Enteric Coronavirus (HECV), Bovine Respiratory Coronavirus (BRCV) and our BECV strains, with the 12 monoclonal antibodies. Human Respiratory Coronavirus (OC43), Porcine Hemagglutinating Encephalitis Virus (HEV) and BECV share common antigenic determinants which are outlined by the 6 non-neutralizing monoclonal antibodies. On the basis of the reactivity of coronaviruses with anti-BECV monoclonal antibodies, a distinction can be easily made between BECV and other coronaviruses, and differences were also detected within the BECV isolates. Interestingly HECV were found to be more closely related to BECV than to human OC43. These results show that monoclonal antibodies are of valuable help for biochemical and antigenic studies as well as for diagnostic procedures.

Animals↗
PubMed1982

Infection of a calf with the enteric coronavirus strain Paris.

A tissue-culture-grown enteric coronavirus infected the whole of the gastrointestinal tract and caused enteritis and diarrhoea in a 10-day-old gnotobiotic Friesian calf. Diarrhoea occurred 2 days after inoculation and excretion of virus in faeces and rectal swabs increased until necropsy at 3 days. Virus growth, as detected by indirect immunofluorescence, virus isolation, and thin section electron microscopy, was most extensive in the epithelium of the colon and rectum at 3 days after inoculation. No virus was detected in other organs or in the pleural, peritoneal and oropharyngeal cavities. The origin and host specificity of this coronavirus is discussed.

Animals↗
PubMed1982

Nuclear localization of aspartate transcabamoylase in Saccharomyces cerevisiae.

The cytochemical technique using the in situ precipitation of orthophosphate ions liberated specifically by the aspartate carbamoyltransferase (ATCase) (EC 2.1.3.2) reaction indicated that in Saccharomyces cerevisiae this enzyme is confined to the nucleus. This observation is in accordance with the result reported by Bernhardt and Davis (1972), Proc. Natl. Acad. Sci. U. S. A. 69:1868-1872) on Neurospora crassa. The nuclear compartmentation was also observed in a mutant strain lacking proteinase B activity. This finding indicates that this proteinase is not involved in the nuclear accumulation of ATCase, and that the activity observed in the nucleus corresponds to the multifunctional form associated with the uracil path-specific carbamoylphosphate synthetase and sensitive to feedback inhibition by UTP. In a ura2 strain transformed by nonintegrated pFL1 plasmids bearing the URA2-ATCase activity encoding gene, the lead phosphate precipitate was observed predominantly in the cytoplasm. This finding enhances the reliability of the technique used by eliminating the possibility of an artifactual displacement of an originally cytoplasmic reaction product during the preparation of the material for electron microscopy. On the other hand, nuclei isolated under hypoosmotic conditions do not exhibit the ATCase activity that is recovered in the cytosolic fractions after differential centrifugation of the lysate in Percoll gradient. A release of the protein from the nuclei during the lysis step, consistent with its nucleoplasmic localization, is postulated.

Aspartate Carbamoyltransferase↗
PubMed1982

Bovine enteric coronavirus structure as studied by a freeze-drying technique.

A strain of bovine coronavirus (F15) was studied by electron microscopy using a freeze-drying technique. Purified coronavirus preparations show three different categories of image: (i) 'blackberry-like' virions, (ii) virions with a smooth depression at their surface, and (iii) apparently broken particles showing very clearly the areas of spike insertion in the virus membrane. Virus projections resemble 'mushrooms' with the 'stalk' inserted at the virus membrane. A model of the virion structure is proposed.

Animals↗
PubMed1981

[Adaptation of an isolate of bovine enteritic coronavirus to serial growth in cell culture and characterization of the virus (author's transl)].

Coronaviruses are known to behave as pathogens in a variety of animal species. Their multiplication in the differentiated enterocytes of the intestinal tract induces a severe diarrheic syndrome which may lead to death. To study these viruses and to progress in the development of prophylactic and diagnostic methods, it is essential to succeed in adapting the agents to serial growth in cell culture. In spite of several attempts adaptation to primary cell cultures could be obtained in the past only for two isolates. The present work describes the methodology which enabled us to succeed in the adaptation of a bovine enteric coronavirus isolated in France to primary calf kidney cells, and reports results on the characteristics of this virus. Adaptation to serial growth was realized at 34 degrees C in the following way: 3 passages each lasting 8 to 10 days followed by 16 passages each lasting 6 days. From the 20th passage on the duration of incubation was reduced to 4 days. Virus growth was checked using an indirect immunofluorescence test. During the first passages only a few dispersed positive cells could be observed but later on small foci of immunofluorescent cells did appear. By the 35th passage infective titers did not exceed 1 x 10(5) TCID50/ml and cytopathic effects were always very discrete. When the susceptibility of different cell-types to this coronavirus strain (G110) was checked we found that only bovine cells and the human HRT18 cell-line were able to replicate the virus. In HRT18 cells titers as high as 5 x 10(7) TCID50/ml could be obtained at the first passage of G110 strain, previously adapted to primary calf kidney cells. As regards the antigenic properties of G110 virus no difference could be established between this strain and the Nebraska isolate (NCDCV) neither by indirect immunofluorescence test nor by indirect neutralization test. The G110 strain agglutinates rat and mouse erythrocytes. The density of purified virions in mouse gradients is 1.19 and the morphology of the particles is characteristic of a coronavirus.

Animals↗
PubMed1980

[Association of coronavirus infection with hemorrhagic entercolitis in newborn infants].

The existence of a widely spread corona virus epidemic enabled us to associate this infection with necrotizing hemorrhagic enterocolitis in newborn infants. Virus is detected in the stools by direct electron microscopic examination. Virions are found agglutinated in the gut during convalescence, as they are by circulating antibodies. Arguments supporting a possible etiological role of this infection are given.

Antibodies, Viral↗
PubMed1980

[A cell line particularly susceptible to bovine enteric Coronavirus replication: HRT 18 cells].

Bovine enteric Corona virus (BEC) multiplies spontaneously with very high efficiency in HRT 18 cells; this line established from human rectum adenocarcinoma presents some properties of the differentiated brush border cell of the intestinal villi. Titers obtained are very high (5 x 10(7) TCID 50/ml virus strain F15). The virus produced had the characteristic of BEC: shape, spikes, density 1.19, hemadsorption and hemagglutination of rat erythrocytes. Human and dog enteritic corona viruses replicate also in HRT 18 cells.

Adenocarcinoma↗
PubMed1979

Activation of rotavirus RNA polymerase by calcium chelation.

Two types of particles were isolated during purification of rotavirus. Dense (D) particles have a density of 1.38 in CsCl and exhibit spontaneously a fully active endogenous transcriptase. Light (L) particles (density of 1.36 in CsCl) need to be treated with chelating agents to show a polymerase activity. The activation process of L particles was studied under strictly controlled monovalent, divalent, and hydrogen ion concentrations. These experiments demonstrate that i) activation is not affected by the ionic strength ii) activation occurs only at a pH higher than 7.1 iii) a low concentration of chelating agent (40 muM EDTA) is sufficient to activate the enzyme. Treatment of particles with EGTA, which chelates selectively Ca2+, leads to unmasking even in the presence of magnesium, indicating that the concentration of free calcium ions plays a major role in the activation process. Various glycosidases, detergents, and chelating agents were tested in respect to unmasking properties. Of these compound only chelating agents turned out to be efficient. Following activation, two glycopeptides were solubilized. These glycopeptides have an apparent molecular weight of 34,000 and 31,000 daltons and react with concanavalin A. The role of Ca2+ upon the stability of virus particles, and the activation of the endogenous transcriptase in vitro and in the infected cells is discussed.

Animals↗