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G Martin

Publications and source records attributed to G Martin.

At least 361 records · Page 20Linked to original sources
PubMed1985

Isolation of a clone coding for the alpha-subunit of a mouse acetylcholine receptor.

The mouse cell line BC3H-I synthesizes an acetylcholine receptor (AChR) with the pharmacological properties of a muscle nicotinic cholinergic receptor. We have purified mRNA from this cell line and used the size-fractionated poly(A)+RNA to produce a cDNA library of approximately 50,000 clones. The library was screened with a subclone containing genomic sequences coding for the putative acetylcholine-binding site of the alpha-subunit of chicken AChR. We obtained a plasmid, pMAR alpha 15, with a 1,717-base pair insert. The insert cDNA has 26 nucleotides at the 5'-end which code for a portion of the signal peptide followed by a single open reading frame of 1,311 nucleotides which code for a protein of 49,896 daltons. The insert has 377 bases of 3'-untranslated sequence with 3 polyadenylation sites. Radiolabeled plasmid DNA has been used to identify homologous RNA species of about 2 kilobases in Northern blot analyses of poly(A)+ selected RNA from BC3H-I cells. A similar size mRNA is seen in innervated mouse diaphragm and leg muscle, and both mouse and rat brain. Comparisons of the deduced amino acid sequence of the mouse AChR alpha-subunit with Torpedo marmorata, T. californica, chicken, human, and calf sequences show overall homologies of 80%, 80%, 86%, 96%, and 95%, respectively. More detailed analyses reveal a non-random distribution of amino acid substitutions in several structural domains. Based on the absolute conservation of cysteine residues, a new model for the arrangement of the disulfide bonds in the extracellular portion of the alpha-subunit is proposed.

Amino Acid Sequence↗
PubMed1985

Subtyping lymphocytes in peripheral blood by immunoperoxidase labeling and light scatter/absorption flow cytometry.

Lymphocyte subpopulations in a whole-blood sample can be detected by adapting mouse monoclonal antibodies (MAbs) and peroxidase (EC 1.11.1.7) labeling to a flow cytometer equipped with a tungsten-halogen light source and scatter/absorption optics (Technicon H6000). In the optimized cytochemical conditions each cell population generates a distinct, well-separated cluster, for accurate "thresholding" of the surface-antigen negative and positive lymphocyte populations in the presence of other leukocytes. After reaction with MAb, the erythrocytes are lysed, and the lymphocytes and other leukocytes are fixed. Biotinylated anti-mouse IgG, used as a bridge, amplifies the response from the avidin-peroxidase label. Granulocytes and monocytes, which have high endogenous peroxidase activity, and the labeled lymphocytes are stained in a specific amount of hydrogen peroxide plus 4-chloro-1-naphthol in 4-(2-hydroxyethyl)-1-piperazine-ethanesulfonic acid buffer. Accuracy and precision are equivalent to those of flow cytometers that measure immunofluorescence (e.g., Ortho Spectrum III), as demonstrated with OKT3, OKT4, OKT8, OKT11, and Leu 12 MAbs.

Adult↗
PubMed1985

[Carpo-metacarpal dislocation of the 5th digit with fracture of the hamate bone. Apropos of a recent case].

The authors report one case of recent fracture of the hamate with dorsal dislocation of the fifth metacarpal. This type of lesion is infrequent and may be misdiagnosed unless appropriate radiographs are taken with oblique views. The lesion was not stable after closed reduction and required fixation with a pin through the hamate fracture. The functional result was satisfactory.

Adult↗
PubMed1984

[Gingivectomy].

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Gingivectomy↗
PubMed1984

Evidence for a homogeneous lateral distribution of lipids in a bacterial membrane. A photo cross-linking approach using anthracene as a photoactivable group.

A new photo cross-linking method has been developed for the study of the lateral distribution of lipids in natural membranes, which uses anthracene as a photoactivable group. This method, which rests on the potentiality of anthracene to form covalently bound dimers upon irradiation around 340-380 nm has been applied to the membrane lipids (dimannosyl diacylglycerol, phosphatidylglycerol, phosphatidylinositol) of the bacterium Micrococcus luteus. These glyco- and phospholipids were anthracene labelled by metabolically incorporating the synthetic 9-(2-anthryl)nonanoic acid. The following sequential procedure was used: dimerization of the anthracene-labelled lipids in the membrane by irradiation of the intact cells at 360 nm; extraction of the lipids and thin-layer chromatography in the first dimension to separate the various lipid dimers from the monomers; partial dedimerization of the lipid dimers by illumination of the chromatogram at around 250-280 nm; chromatography in the second dimension to separate the native lipid monomers from the corresponding residual lipid dimers. On account of the occurrence of the 3 hetero dimers phosphatidylglycerol-dimannosyl diacylglycerol, phosphatidylinositol-dimannosyl diacylglycerol and phosphatidylglycerol-phosphatidylinositol after irradiating the cells, it is concluded that in this bacterial membrane, dimannosyl diacylglycerol, phosphatidylglycerol and phosphatidylinositol are homogeneously distributed.

Anthracenes↗
PubMed1984

The hyperglycemic neuropeptide of the terrestrial isopod, Porcellio dilatatus. I. Isolation and characterization.

From isolated sinus glands of Porcellio dilatatus, a hyperglycemic neuropeptide (CHH) was purified by means of a single, two-step purification procedure which consisted of gel chromatography on Sephadex G-50, followed by high-performance liquid chromatography. The 5800- to 6100-Da peptide contains 50-52 amino acids residues. The amino acid composition is (Pro, Ile)1; His1-2; (Thr, Ser, Gly, Met, Tyr)2; (Val, Phe, Lys)3; (Ala, 1/2Cys, Leu, Arg)4; Glx5; Asx7; Trp, n.d. The amino acid composition differs from that of two decapod CHHs analyzed thus far. The N-terminus is blocked. The neuropeptide exhibits little or no interspecific hyperglycemic effect in the brachyuran, Uca pugilator, and its cross-reactivity and potency in the RIA for Carcinus-CHH is very low.

Amino Acids↗
PubMed1984

The hyperglycemic neuropeptide of the terrestrial isopod, Porcellio dilatatus. II. Immunocytochemical demonstration in neurosecretory structures of the nervous system.

By use of an rabbit antiserum raised against the crustacean hyperglycemic hormone (CHH) of the shore crab, Carcinus maenas, CHH-producing perikarya were detected in the brain of the isopod, Porcellio dilatatus, by the double-antibody immunofluorescence technique. The course of the secretory axons to the neurohemal organ, the sinus gland, could be traced. The sinus gland also exhibited strong fluorescence. The reaction was very specific, no other structures gave appreciable immunofluorescence. There are two CHH cells in each hemisphere of the brain, located in the medio-rostral part of the protocerebrum. This area appears to correspond to the medulla terminalis of decapods. The cells are aldehyde fuchsin-positive and have been previously described as beta 1 cells. The immunofluorescence could be inhibited by preabsorption of the antiserum with pure Carcinus-CHH.

Animals↗
PubMed1984

Training developmentally handicapped persons as supervisors in sheltered workshops.

Developmentally handicapped persons were taught to apply a behavioral supervisory strategy to maintain work rates of other developmentally handicapped clients in a sheltered workshop. In two experiments, each with two subjects, training procedures were examined in a multiple baseline across supervisory components within subjects. Results clearly demonstrated that the subjects learned to apply the supervisory components as a function of the training procedures. The subjects were approximately as effective as were regular staff for maintaining production rates of the workshop clients. Potential benefits of the supervisory training for the subjects as well as for the staff were discussed. The results suggest that the teaching of developmentally handicapped persons to perform more complex supervisory activities in sheltered work settings deserves greater attention than it has received in the past.

Adolescent↗
PubMed1984

Time constant of isovolumic pressure fall: new numerical approaches and significance.

The effects of left ventricular diastolic pressure changes on the values of the time constant (T) of isovolumic pressure fall are controversial. Normally, T is calculated either by linear regression of 1n left ventricular pressure (LVP) vs. time (TL) or by using an exponential model with asymptote (PB, extrapolated base-line pressure to which LVP would fall if decay continued indefinitely). This study, in intact dogs, has been designed to revise the effects that drugs that alter load (angiotensin and nitroprusside, without and with autonomic blockade) and inotropism (isoproterenol and propranolol) might have on the relaxation rate using different numerical methods. We found that 1) the upward or downward translation of the LVP curve had an important effect on the value of TL calculated by the semilogarithmic method; 2) when a model with asymptote was used, the simultaneous changes of T and PB, were not related to the dose of the drug; 3) the values of TL and the -dP/dt values extrapolated to 15 mmHg from a model with PB, were much more sensitive to beta-agonist or antagonist drugs than to others whose action was through load alteration. We feel that some of the earlier studies on relaxation rate determinants should be revised as possibly some of the conclusions have been based on artifacts introduced by the method chosen for the computation of the relaxation parameters.

Angiotensin II↗
PubMed1984

Comparison of the effects of betamethasone and L-carnitine on dipalmitoylphosphatidylcholine content and phosphatidylcholine species composition in fetal rat lungs.

Antepartum administration of L-carnitine to pregnant rats results in an increase of both total phospholipid (80 +/- 11 mg/g dry weight (dw); mean +/- SD) and dipalmitoylphosphatidylcholine (DPPC) content (7.7 +/- 2.1 mg/g dw) in fetal lungs as compared to controls (72 +/- 10 and 7.0 +/- 2.5 mg/g dw, respectively). On the other hand, no effect of L-carnitine could be demonstrated on the DPPC portion in the total phosphatidylcholine (PC) or on the portion of palmitic acid in the PC fatty acids. Betamethasone elevated the DPPC content in fetal lungs (8.1 +/- 2.0 versus 7.0 +/- 2.5 mg/g dw in the controls), while total phospholipid content remained unaffected (71 +/- 19 versus 72 +/- 10 mg/g dw). The portion of DPPC in the PC species increased significantly (p less than 0.01) from 27.6 +/- 4.5 in the fetal lungs of the control group to 34.2 +/- 3.3 in the lungs of the betamethasone-treated group, while the palmitic acid portion in the PC fatty acids was nearly unchanged (45.9 +/- 3.2 versus 43.9 +/- 2.6 in the controls). Further, after betamethasone treatment, a significant diminution (p less than 0.01) of the monoenic PC 32 species (palmitoyl-palmitoleyl PC and palmitoleyl-palmitoyl-PC) and the PC 34 species (consisting primarily of palmitoyl-oleoyl-PC) could be demonstrated both in absolute and relative terms. This is in agreement with a significant reduction of the portions of palmitoleic (p less than 0.01) and oleic (p less than 0.05) acids in the total PC fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

[Course and prognosis in sudden deafness].

Follow up audiograms were done at periods up to 15 years after sudden deafness on 69 patients. The average value of the pure tone threshold continued to decrease linearally at about 1.15 dB per year. In a few cases (21%) however, improvement in hearing was observed even up to 12 years after sudden deafness. 28.6% of the patients recovered later without having shown any improvement in hearing during treatment with infusions. On the other hand 8.3% of the patients had a relapse. The immediate improvement in hearing following in patient treatment showed no correlation to the subsequent audiogram. Neither basic diseases, accompanying tinnitus, vestibular involvement or delayed treatment showed any influence on long-term development of hearing. The results of treatment with different medicaments reached a plateau. No significant effect could be determined for long-term treatment with vasodilators. In view of the high rate of spontaneous remissions the success of treatment for sudden deafness must be critically evaluated.

Audiometry, Pure-Tone↗
PubMed1984

Oxidoreduction sites and relationships of spiroplasmas with insect cells in culture.

We have previously shown that Spiroplasma citri oxidoreduction sites, as revealed by the reduction of potassium tellurite into electron-dense tellurium crystals detectable by electron microscopy, were located at the blunt end of the organisms. The time of incubation of S. citri in potassium tellurite had no influence on the labeling. We have investigated the presence and location of oxidoreduction sites for other spiroplasmas such as the corn stunt spiroplasma (CSS), 277F, B88, BNR1 and PPS1. For all of these strains (except CSS, which is similar to S. citri), the location of oxidoreduction sites was affected by the time of incubation in potassium tellurite, and could be observed in different locations of the helix. 277F showed first labeling at the blunt end and a second, strong labeling at the tapered end. The other strains showed labeling all along the helix, but labeling at the blunt end generally appeared first. When Drosophila (Dm-1) cell cultures were infected with S. citri or 277F, the organisms adsorbed to the cells. Observation of infected cells by electron microscopy revealed that S. citri attached to the cells by the blunt end, while 277F attached either by the blunt end or the tapered one. The infection of leafhopper cell cultures (AS-2) with S. citri has been followed by transmission electron microscopy after incorporation of tritiated thymidine in the organism, and an immunocytochemical method has been developed to locate the organisms inside the cells.

Animals↗
PubMed1983

Lactate, alanine and glutamine metabolism in isolated canine pup liver cells.

The metabolism of lactate, alanine and glutamine was studied in isolated canine liver cells. Lactate proved a better gluconeogenic precursor than alanine and glutamine. Glucose was synthesized at similar rates from both amino acids and ureogenesis from glutamine was double that from alanine. As in isolated rat liver cells, glucose and urea represented the main carbon and nitrogenous end-products of lactate, alanine and glutamine metabolism. Taken with the known levels of hepatic uptake of glutamine and alanine, these findings suggest that in the fasted dog, unlike in the fasted rat, glutamine and not alanine is the main transporter of nitrogen and carbon from muscle to liver for urea synthesis and gluconeogenesis.

Alanine↗
PubMed1983

Evolution of Drosophila repetitive-dispersed DNA.

We have examined the phylogenetic distribution of a spectrum of Drosophila repetitive-dispersed DNAs ranging from structurally complex transposable elements to scrambled middle repetitive sequences. Our data suggest that unlike typical "genes" these DNAs are unstable components of the drosophilid genome. The unusual behavior of these repetitive-dispersed DNAs raises the possibility that this type of sequence may have an important role in the evolution of the family Drosophilidae.

Animals↗