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Biomedical subjects

M Garret

Publications and source records attributed to M Garret.

At least 37 records · Page 2Linked to original sources
PubMed1989

Specific amplification of a DNA sequence common to all Chlamydia trachomatis serovars using the polymerase chain reaction.

Enzymatic DNA amplification was applied to DNA and elementary bodies of C. trachomatis. Oligonucleotide primers were chosen in a sequence of a conserved domain of the major outer membrane protein to generate the amplification of a 129-base pair fragment. This sequence was amplified in the 15 serovars of C. trachomatis; however, serovar J gave a weaker signal than the others. The specificity was controlled by EcoRI restriction enzyme digestion and Southern analysis using an internal probe of the amplified sequence. No cross-reaction was shown with DNA of 11 other bacteria. Thus, enzymatic DNA amplification by the polymerase chain reaction appears to be a potential tool for the specific detection of C. trachomatis.

Base Sequence↗
PubMed1989

Detection of Mycoplasma pneumoniae by using the polymerase chain reaction.

The polymerase chain reaction (PCR) technique was used to detect Mycoplasma pneumoniae. A specific DNA sequence for M. pneumoniae was selected from a genomic library, and two oligonucleotides were chosen in this sequence to give an amplified fragment of 144 base pairs. We show that DNA from different M. pneumoniae strains can be detected by PCR, with DNA from other Mycoplasma species giving negative results. Analysis of biological samples (throat swabs) obtained from hamsters that were experimentally infected with M. pneumoniae showed that PCR was more sensitive and reliable than conventional culture techniques for the detection of M. pneumoniae. Initial experiments on artificially seeded human bronchoalveolar lavages showed that PCR can be used to detect 10(2) to 10(3) organisms.

Animals↗
PubMed1988

[Hypergastrin and hyperprolactin syndrome caused by mucinous cystadenoma of the ovary].

We report a case of a clinically and biologically typical hypergastrinemia syndrome due to ovarian mucinous cystadenoma. When examined under histoimmunofluorescence, this "border-line" tumor was shown to contain a polymorphous endocrine cell proliferation, composed primarily of G cells and, to some degree, of D cells. Electron microscopic study further evidenced a small amount of prolactin containing cells, which coincided with elevated prolactin-levels in blood. Ovariectomy combined with vagotomy and pyloroplasty resulted in a prompt disappearance of both clinical and biological abnormalities. Ovarian mucinous cystadenomas have been known for a long time to contain endocrine cells, but only five cases, including the present one, have been described with fully developed endocrine expression. We suggest that this particular condition could be more frequent than generally admitted, and could justify systematic screening for mucinous cystadenoma in the case of peptide hormone dysfunction.

Adult↗
PubMed1986

Inhibition of human pancreatic elastase II activity on human aortic elastin by human alpha 2-macroglobulin.

Human alpha 2-macroglobulin-human pancreatic elastase II binding were investigated using a homologous substrate, human aortic elastin, in order to test the enzymatic activity. We demonstrated that two moles of alpha 2-M are required to inhibit one mole of HPEII when the enzyme is added to a mixture of elastin and alpha 2-M. In addition, when the elastase-alpha 2-M complex is prepared under some circumstances, it exhibits an elastinolytic activity.

Aorta↗
PubMed1986

Tryptophanyl-tRNA synthetase is a major soluble protein species in bovine pancreas.

Besides their central role in protein synthesis, aminoacyl-tRNA synthetases have been found or thought to be involved in other processes. We present here a study showing that tryptophanyl-tRNA synthetase has a surprising tissular distribution. Indeed, immunochemical determinations showed that in several bovine organs such as liver, kidney and heart, tryptophanyl-tRNA synthetase constitutes, as expected, about 0.02% of soluble proteins. In spleen, brain cortex, stomach, cerebellum or duodenum, this amount is about 10-times higher, and in pancreas it is 100-fold. There is no correlation between these amounts and the RNA content of the organs. Moreover, the concentration of another aminoacyl-tRNA synthetase (methionyl-tRNA synthetase) is higher in liver than in pancreas, while the amount of tRNATrp is not higher in pancreas than in liver as compared to other tRNAs. Among several interpretations, it is possible that tryptophanyl-tRNA synthetase is involved in a function other than tRNA aminoacylation. This unknown function would be specific to the differentiated organs, since fetal cerebellum and fetal pancreas contain the same amount of tryptophanyl-tRNA synthetase as adult liver.

Amino Acyl-tRNA Synthetases↗
PubMed1985

Formycin 3' end modified tRNATrp. Recognition by avian myeloblastosis virus reverse transcriptase and primer function.

Primer tRNATrp has been modified at the 3' end by adenosine analogues: 2'deoxyadenosine, 3'deoxyadenosine, 3' amino-3' deoxyadenosine and formycin. Aminoacylation of modified tRNATrp with cognate aminoacyl-tRNA synthetase and primer function for DNA synthesis catalyzed by AMV reverse transcriptase have been studied. The tRNATrp was able to accept tryptophan but did not initiate the DNA synthesis directed by 35S AMV RNA. Recognition of modified tRNATrp by AMV reverse transcriptase was not affected as followed by enzyme-tRNA complex formation. The functional consequences of these effects are discussed.

Adenosine↗
PubMed1984

Interactions between avian myeloblastosis reverse transcriptase and tRNATrp. Mapping of complexed tRNA with chemicals and nucleases.

The interactions between beef tRNATrp with avian myeloblastosis reverse transcriptase have been studied by statistical chemical modifications of phosphate (ethylnitrosourea) and cytidine (dimethyl sulfate) residues, as well as by digestion of complexed tRNA by Cobra venom nuclease and Neurospora crassa endonuclease. Results with nucleases and chemicals show that reverse transcriptase interacts preferentially with the D arm, the anticodon stem and the T psi stem. All these regions are located in the outside of the L-shaped structure of tRNA. This domain of interaction is different to that reported previously in the complex of beef tRNA with the cognate aminoacyl-tRNA synthetase (M. Garret et al.; Eur. J. Biochem. In press). Avian reverse transcriptase destabilizes the region of tRNA where most of the tertiary interactions maintaining the structure of tRNA are located.

Alkylation↗
PubMed1984

Tertiary structure of animal tRNATrp in solution and interaction of tRNATrp with tryptophanyl-tRNA synthetase.

Alkylation in beef tRNATrp of phosphodiester bonds by ethylnitrosourea and of N-7 in guanosines and N-3 in cytidines by dimethyl sulfate and carbethoxylation of N-7 in adenosines by diethyl pyrocarbonate were investigated under various conditions. This enabled us to probe the accessibility of tRNA functional groups and to investigate the structure of tRNATrp in solution as well as its interactions with tryptophanyl-tRNA synthetase. The phosphate reactivity towards ethylnitrosourea of unfolded tRNA was compared to that of native tRNA. The pattern of phosphate alkylation of tRNATrp is very similar to that found with other tRNAs studied before using the same approach with protected phosphates mainly located in the D and T psi arms. Base modification experiments showed a striking similarity in the reactivity of conserved bases known to be involved in secondary and tertiary interactions. Differences are found with yeast tRNAPhe since beef tRNATrp showed a more stable D stem and a less stable T psi stem. When alkylation by ethylnitrosourea was studied with the tRNATrp X tryptophanyl-tRNA synthetase complex we found that phosphates located at the 5' side of the anticodon stem and in the anticodon loop were strongly protected against the reagent. The alkylation at the N-3 position of the two cytidines in the CCA anticodon was clearly diminished in the synthetase X tRNA complex as compared with the modification in free tRNATrp; in contrast the two cytidines of the terminal CCA in the acceptor stem are not protected by the synthetase. The involvement of the anticodon region of tRNATrp in the recognition process with tryptophanyl-tRNA synthetase was confirmed in nuclease S1 mapping experiments.

Alkylation↗
PubMed1984

[Sarcoidosis at the Cochin University Hospital Center from 1975 to 1982].

An analysis of 80 cases of sarcoidosis admitted to the departments of respiratory medicine (36), rheumatology (19) and internal medicine (25) over a 7 year period, revealed a wide range of clinical presentations; there was a higher incidence of associated disease and a greater number of localisations of the disease in patients admitted to the department of internal medicine than in those admitted to the other two departments. On the other hand, bronchial biopsy was more commonly positive in patients admitted to the department of respiratory medicine whose respiratory function was more disturbed than the patients in the other two departments. The patients referred to the departments of rheumatology and internal medicine without radiological respiratory involvement had respiratory function tests and positive alveolar lavages. The prognosis was the same in all three departments; 50 p. 100 were treated with steroids. The recruitment of the patients in this series allows a different evaluation of the disease compared to series reported from more specialised departments.

Adolescent↗
PubMed1983

The in vitro inhibition of DNA polymerase alpha and avian reverse transcriptase by novobiocin.

Novobiocin inhibits animal DNA polymerase alpha and avian reverse transcriptase activities when these enzymes are assayed in vitro with activated DNA as template. Under the same conditions DNA polymerase beta and gamma are much less inhibited. DNA polymerase alpha and reverse transcriptase are inhibited by different mechanisms: in the case of the retroviral enzyme the effect of novobiocin is not overcome by dilution of the drug, while in the case of polymerase alpha the inhibition disappeared after novobiocin dilution. The inhibition of polymerase alpha by novobiocin is non-competitive with respect to the TTP precursor or activated DNA. The irreversible inactivation of reverse transcriptase by novobiocin leads to the loss of the enzyme affinity for primer tRNATrp. Moreover, novobiocin inhibits the partial unwinding of the 3' end of tRNATrp by reverse transcriptase.

Animals↗