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Biomedical subjects

C J Turner

Publications and source records attributed to C J Turner.

At least 37 records · Page 2Linked to original sources
PubMed1988

A high-performance liquid chromatographic assay for reduced and oxidised glutathione in embryonic, neonatal, and adult tissues using a porous graphite electrochemical detector.

A high-performance liquid chromatographic (HPLC) assay employing a porous graphite electrochemical (EC) detector is described for the simultaneous quantification of reduced glutathione (GSH) and oxidised glutathione (GSSG) in embryonic, neonatal, and adult tissues. Samples were prepared by homogenization in 5% trichloracetic acid, centrifugation, filtration of the supernatant, and injection into the HPLC. Separation was achieved isocratically within 16 min on a 15 cm reversed-phase C18 analytical column with a particle size of 5 micron using an inexpensive mobile phase containing 2-propanol and water (2.8:100) with camphorsulfonic acid and phosphoric acid. The respective limits of detection for GSH and GSSG were 1.5 and 3 ng with a 6 microliter sample using a 3:1 signal to noise ratio. In addition to routine samples, the assay was sufficiently sensitive to detect picomole quantities of GSH and GSSG in small samples, such as a single mouse embryo, gestational day 9, weighing approximately 1 mg. The advantages and disadvantages of the method are compared with other assays for GSH and GSSG published in the literature.

Animals↗
PubMed1988

Comparative radiolabeling and distribution of a tumour-directed monoclonal antibody.

The monoclonal antibody (MAb) 155H.7, raised against a synthetic beta-anomer of the Thomsen-Friedenreich antigen (S-TAG), was radioiodinated using iodine monochloride, chloramine-T and Iodogen and radiolabeled with 111In using the bromoacetamido-derivative of benzyl-EDTA. The in vitro immunoreactivity of the MAb was assessed using an ELISA with the S-TAG and the in vivo distribution of the radioiodinated and radiochelated MAb was determined in the murine mammary carcinoma TA3/Ha tumour model. Both chloramine-T and iodine monochloride radioiodination greatly reduced the immunoreactivity of the MAb compared to radioiodination using Iodogen. Bifunctional chelate labeling was comparable to Iodogen in reducing the immunoreactivity of the MAb and subsequent chelation of 111In did not further compromise the immunoreactivity of the MAb. The in vivo distribution data showed significantly different distributions of the radiolabels after injection of the radioiodinated and radiochelated MAb. The 131I-MAb showed some tumour association as compared to the distribution of an 125I-non-specific protein and the data also indicates that there is preferential dehalogenation of the radioiodinated MAb. 111In from the radiochelated MAb showed significantly higher uptake in the tumour than 131I from the 131I-MAb. It is suggested that the differing fates of the two radiolabels within the tumour cell is responsible for the difference in retention observed and not necessarily due to the lack of MAb uptake by the tumour. Overall, the radiochelate label for MAb 155H.7 appears to be superior to radioiodine for in vivo use.

Animals↗
PubMed1986

Comparative studies of radiocitrates in oncological models--I. 99mTc citrate and 67Ga citrate uptake by EMT-6 tumors in mice.

67Ga citrate and 99mTc citrate (Solcocitran) were injected sequentially, with an interval of 48 h, into Balb/c mice bearing transplanted EMT-6 tumors. Tissue distributions of 67Ga and 99mTc were measured simultaneously at intervals of 1, 3, 5 and 8 h after injection of the 99mTc citrate (49, 51, 53 and 56 h after 67Ga citrate). Maximal tumor:blood ratios for 67Ga and 99mTc were 13.8 +/- 3.2 and 4.0 +/- 1.0 respectively, both occurring at the final period. The maximum tumor index (T.I. = T:B X % dose/g) for 67Ga was 71 +/- 23% 56 h after injection, and for 99mTc was 13 +/- 12% 1 h after injection. Liver, kidney and spleen had equal or higher concentrations of radioactivity than tumor for either radiotracer. The somewhat higher tumor:blood ratio for 67Ga citrate was offset by the time required for this optimum to be reached. Alternatively, the best 99mTc citrate tumor:blood ratios were attained within 8 h, with less liver and gut radioactivity. These data fall within the range of results from other clinical and animal model studies of 67Ga citrate and 99mTc citrate. In view of the radiation dose, the inconvenience of the 48-72 h wait, and the cost of 67Ga, and because neither radiopharmaceutical is tumor specific, 99mTc citrate may have a place in early oncological screening. The results are discussed as part of a comprehensive review of the 99mTc citrate literature.

Animals↗
PubMed1985

Phosphorus two-dimensional NMR spectroscopy of perfused rat hearts.

The theory behind the technique of two-dimensional (2-D) NMR is presented with particular reference to 2-D J-spectroscopy and 2-D exchange spectroscopy. Experiments are described in which both these types of 2-D NMR are applied to the isolated perfused rat heart. Possible advantages of 2-D techniques and future applications to physiological systems are discussed.

Animals↗
PubMed1985

The effect of amphotericin B on 67Ga biodistribution.

The effect of Amphotericin B (AMB) on radiogallium biodistribution in mice was studied at various time intervals. Two doses of AMB (1 mg/kg and 10 mg/kg) were administered intraperitoneally into mice bearing EMT-6 mammary sarcomas. The tumor and tissue uptakes of 67Ga were calculated when the radioactivity was administered either as 67Ga-citrate or 67Ga-transferrin (Ga-Tf). The role of transferrin was also investigated by using doubly-labeled 67Ga-125I-Tf. Our results indicate that both the doses of AMB and the chemical form of the radiogallium administered affect the pattern of distribution in some distinct fashion. It was also found that although the administration of AMB results in an increase in tumor-associated transferrin, this does not necessarily result in a concomitant increase in radiogallium uptake. In general, the effects of AMB on various tissues uptake of 67Ga appear to be related to both acute and subacute toxicity.

Amphotericin B↗
PubMed1981

Growth of sympathetic nerve terminals in the adult rat.

This report presents evidence that in adult life, in the absence of any experimentally-induced stimulus, the density of sympathetic nerve terminals increases in rat submaxillary salivary glands, suggesting that sympathetic nerve terminal growth continues in adult life. Several theories which have been proposed to account for nerve terminal growth in adult animals are discussed in light of experimental results.

Adrenergic Fibers↗
PubMed1981

The nature of afferents from the large dorsal neck muscles that project to the superior colliculus in the cat.

1. A 3.5-5 mm passive stretch of dorsal neck muscles at velocities of 50 mm/sec, a stimulus adequate to excite most neck muscle spindles, was usually ineffective in eliciting unit discharge in the superior colliculus. The sudden release of muscle tension was effective and excited fifty-seven of sixty-seven units tested. 2. When electrical stimulation of neck muscle nerves was used, a stimulus strength sufficient to excite Group III muscle afferents was usually required to elicit unit discharge in the superior colliculus. 3. It is concluded that the projection from neck muscles to the superior colliculus largely takes origin in Group III afferent whose function remains to be determined. Some contribution to the projection to the superior colliculus from proprioceptive afferents served by larger fibres cannot be ruled out.

Action Potentials↗
PubMed1981

Toxin-induced inhibition of nerve terminal growth.

An in vivo model to permit the quantitative study of the effects of neurotoxins upon nerve terminal growth has been developed and used in practice to test the ability of methyl mercury chloride, leptophos, ethanol, morphine and acrylamide to inhibit nerve terminal growth. The model utilized the sympathetic innervation of rat submaxillary salivary glands. Nerve terminal growth was induced following crush of the sympathetic axons which innervated the submaxillary gland and quantified by measuring the return towards normal values of the density of sympathetic innervation in denervated glands. The nerve crush reduced the density of sympathetic innervation to a very low value but nerve growth began within 9 days and was sufficient to restore the density of innervation to approximately 70% of normal values in three weeks. Restoration of the original density of innervation took between 40 and 60 days. The major advantage of the model is its ability to detect and quantify 30% - 100% inhibition of nerve terminal growth. The major disadvantage is the time required to measure the density of sympathetic innervation though this can be minimized in a number of ways which are discussed. Acrylamide inhibited sympathetic nerve terminal growth without causing degeneration of sympathetic neurones. This demonstrates that toxins can selectively inhibit nerve terminal growth which will result in altered neuronal circuitry and abnormal function. Methyl mercury chloride, leptophos, ethanol and morphine did not inhibit sympathetic nerve terminal growth.

Acrylamide↗
PubMed1980

The relationship of college students' use of marijuana to parental attitudes and drug-taking behavior.

This study was part of an extensive survey of drug use patterns at a small private college in suburban New Jersey during the fall, 1975. Selected items from a questionnaire developed by the Inter-University Drug Survey Council of Metropolitan New York were cross-tabulated in order to examine the relationship between 379 college students' use of marijuana and their parents' attitudes and behavior relative to drug use. Significant results at the 0.01 level were found between (1) time of first marijuana use and parental attitudes toward alcohol and marijuana; (2) time of first marijuana use and parental use of barbiturates, marijuana, and pain-killers; (3) current frequency of marijuana use and parental attitudes toward alcohol and marijuana; and (4) current frequency of marijuana use and parental use of pain-killers.

Adult↗
PubMed1977

Neuronal transport in salamander nerves and its blockade by colchicine.

Neuronal transport and the effects of colchicine on it has been studied in salamander spinal nerves. Cholinesterase (ChE) accumulation above the cut region of a nerve at 12.5 degrees C was shown to depend upon two processes. One caused a transient increase which declined to zero by 24 h; the other was explained by axoplasmic transport. At 22 degrees C the transient change was not observed, but the rate of accumulation attributable to transport increased. The Q10 for this transport over the range 12.5 degrees C--22 degrees C is approximately three. The ChE accumulation in the sensory component of the mixed nerve was about equal to that in the motor. The rate of fast axoplasmic transport of labeled leucine was 56 mm/day at 22 degrees C; if ChE moves at the same rate, then only 7% of the total enzyme is carried by fast axoplasmic transport. The transport of ChE was reduced by at least 50% when nerves were bathed in a 75 mM solution of colchicine for 30 min; this treatment is known not to cause subsequent degeneration of these nerves. The rate of slow flow of labeled material after bathing the nerve trunk in tritiated colchicine was found to be approximately 0.5 mm/day.

Animals↗
PubMed1977

Effect of electrical stimulation of the autonomic nerves on the levels and synthesis of cyclic nucleotides in the rat salivary glands: relationship to enhanced growth.

Electrical stimulation of either the parasympathetic or the sympathetic nerve supply to the parotid and submaxillary glands increases the intracellular level of cyclic GMP and the rate of DNA synthesis and cell division while only sympathetic stimulation raises cyclic AMP levels. The periods of electrical stimulation inducing hyperplasia also raise the cyclic GMP concentration but there is no similar correlation with changes in cyclic AMP levels. However, the extent of hyperplasia induced by parasympathetic and sympathetic stimulation is not directly related to the size of the increase in cyclic GMP concentration that these treatments produce. Changes in cyclic AMP levels are reflected in altered in vitro adenylate cyclase activity. This activity is raised after 2 min sympathetic stimulation and markedly decreased with 30 min sympathetic or parasympathetic stimulation. Guanylate cyclase activity shows no such changes with nerve stimulation.

Adenylyl Cyclases↗
PubMed1975

The effects of electrical stimulation of the autonomic nerves and of drugs on the size of salivary glands and their rate of cell division.

The effects of electrical stimulation of the sympathetic and of the parasympathetic nerves on the size of rat salivary glands have been investigated and compared with those caused by isoproterenol. Sympathetic nerve stimulation increased the size and the mitotic index in the parotid acini; in the submaxillary acini, only the size was increased. These responses varied with the gland studied and the duration of stimulation; the parotid showed the larger increase in the mitotic index and thymidine uptake, the submaxillary the greater degree of cell enlargement. Prolonged electrical stimulation beyond that required to produce the maximum increase in size reduced the enlargement. Sympathetic nerve stimulation caused no enlargement in the extraorbital lacrimal or major sublingual glands. The responses to sympathetic nerve stimulation were inhibited by propranolol (17 nmol/pg), normetanephrine (2 X 45 nmol/g) and mecamylamine (50 nmol/g) but not by phentolamine (13.0 nmol/g) or atropine (7.5 nmol/g). Electric stimulation of the parasympathetic nerves produced no increase in the size or in the mitotic index.

Animals↗