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Biomedical subjects

C M Lee

Publications and source records attributed to C M Lee.

At least 289 records · Page 16Linked to original sources
PubMed1986

Induction of tryptophan degradation in vitro and in vivo: a gamma-interferon-stimulated activity.

Human recombinant gamma interferon (rHuIFN-gamma) was found to induce tryptophan degradation in vitro in human cell cultures and in vivo in participants in phase I clinical trials. When human lung fibroblasts were treated with various concentrations of rHuIFN-gamma, they degraded tryptophan in a dose- and time-dependent manner. No tryptophan degradation was observed when cells were incubated in growth medium alone or in medium supplemented with human recombinant beta-interferon (rHuIFN-beta ser). Similarly human bladder carcinoma cells were induced to catabolize tryptophan after incubation with rHuIFN-gamma, but no activity was observed in untreated cells or cells treated with either rHuIFN-beta ser or human naturally produced alpha-interferon (HuIFN-alpha). When tryptophan plasma levels were measured in cancer patients who had received i.v. bolus injections of rHuIFN-gamma as part of a phase I clinical trial, decreased tryptophan levels were observed when compared with pretreatment values or values obtained from individuals who had received i.v. injections of HuIFN-alpha. Urine analyses were suggestive that plasma tryptophan degradation occurred via the kynurenine catabolic pathway in individuals who received rHuIFN-gamma. We conclude that tryptophan degradation is an activity induced in vitro and in vivo in response to exogenous IFN-gamma but not to IFN-alpha or IFN-beta. Tryptophan degradation may play an important role in the mechanism of antiproliferative, immunologic, and clinical side effects of IFN-gamma.

Carcinoma↗
PubMed1986

The isolation of human sebaceous glands and apocrine sweat glands by shearing.

A new method of isolating human sebaceous and apocrine sweat glands by the repeated dissection of skin biopsies with scissors is described. The success of the technique is attributed to a line of weakness between the investing capsule and the surrounding connective tissue which parts under shear forces. The glands are judged to be viable by: (i) light and electron microscopy; (ii) ATP, ADP and AMP contents of 148.8 +/- 30.3, 30.6 +/- 4.7 and 14.9 +/- 4.7 pmol (mean +/- s.e.m.) for sebaceous glands and 310.2 +/- 34.1, 90.35 +/- 16.3 and 40.1 +/- 11.8 pmol (mean +/- s.e.m.) for apocrine sweat glands, which gave energy charges of 0.84 and 0.81, respectively; and (iii) a rate of sebaceous gland lipogenesis of 39.7 +/- 3.7 pmol glucose incorporated into lipid/gland/h (mean +/- s.e.m.).

Adenine Nucleotides↗
PubMed1986

Electrophysiological studies on isolated human eccrine sweat glands.

Human eccrine sweat glands were isolated by shearing and the potential differences across the basolateral membranes determined using bevelled micro-electrodes filled with 4 M potassium acetate. Stable resting potentials of up to -81 mV were recorded. Alterations in external potassium concentration from 1.2 to 100 mM caused the membrane potential to change over a 70 mV range in cells of high resting potential, indicating that the basolateral membrane is largely potassium permeable. Input impedance was determined by constant current injection and found to be in the range 4-80 M omega. On giving a bolus injection of acetylcholine to produce a final concentration of 10(-6)-10(-7) M, four types of response were observed: depolarization, in a proportion of cells with resting potentials of -66 to -80 mV (n = 19), hyperpolarization, in a group of cells with resting potentials of -47 to -70 mV (n = 22), no change, in some cells of -40 to -81 mV resting potential (n = 22) and micro-electrode dislodgement (n = 8). In cells depolarizing to acetylcholine, the depolarization was short-lived and in thirteen cases was followed by a 'rebound' hyperpolarization. Input impedance decreased during depolarization in one-third (n = 5) of the cells in which satisfactory measurement could be made and increased during the final phase of depolarization or during rebound hyperpolarization. In cells hyperpolarizing to acetylcholine, the hyperpolarization was usually accompanied by an increase in input impedance. In ten of the twenty-two cells which showed no change to a first dose of acetylcholine, the agonist was administered at least two more times. In two cells (resting potentials -62 mV, -64 mV) a hyperpolarization was observed whereas in three others (resting potentials -66 mV, -70 mV, -81 mV) depolarization occurred. The effects of acetylcholine, whether depolarizing or hyperpolarizing, were reversibly inhibited by atropine and irreversibly reduced by ouabain. Experiments performed on glands maintained for up to 30 h in supplemented RPMI 1640 tissue culture medium yielded essentially similar results to those performed on freshly isolated glands.

Acetylcholine↗
PubMed1986

Isolation of ducts from the pancreas of copper-deficient rats.

A technique is described, involving tissue dissociation and micro-dissection, for the isolation of interlobular ducts from the pancreas of copper-deficient rats. The average length and outside diameter of the isolated ducts were 589.0 +/- 18.6 and 78.1 +/- 1.6 micron (mean +/- S.E.M., n = 425) respectively. Between twenty and fifty ducts could be obtained from each pancreas. Frequently, the smaller intralobular ducts, which had outside diameters of between 15 and 25 micron, were observed as branches of the interlobular ducts. Light and electron microscopy showed that the isolated ducts were structurally intact, and that the epithelial cells possessed all the typical ultrastructural features of duct cells within the gland of copper-replete rats. The isolated ducts consumed oxygen at a rate of 2.27 +/- 0.55 ml O2/min X 100 g wet weight duct epithelium (n = 6). The concentrations of ATP, ADP and AMP in the ducts were 3.78 +/- 0.81, 0.68 +/- 0.19 and 0.41 +/- 0.13 mmol/l duct epithelium (n = 8) respectively. These data give values for ATP:ADP and ATP:AMP ratios of 5.6:1 and 9.2:1 respectively, and an energy charge of 0.85 +/- 0.01 (n = 8) suggesting that the epithelial cells are healthy and in a stable metabolic state. In the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (0.67 mM), the basal concentration of cyclic AMP in the isolated ducts was 17.4 +/- 0.7 mumol/l duct epithelium (n = 3). Secretin (0.1 nM-1 microM) caused a dose-related increase in cyclic AMP content up to a maximum of 376.0 +/- 85.3 mumol/l duct epithelium (n = 4). This indicates that the epithelial cells possess secretin receptors, and that these receptors can be functionally linked to adenylate cyclase.

Adenine Nucleotides↗
PubMed1986

The primary culture of epithelia from the secretory coil and collecting duct of normal human and cystic fibrotic eccrine sweat glands.

Isolated human eccrine sweat glands have been microdissected into their secretory and reabsorptive components. Complete separation of these epithelia was confirmed by differential uptake of Neutral Red stain by an intermediate section of gland containing the junction between the secretory coil and the collecting duct. Primary cultures were obtained from explants of both tissues in medium RPMI-1640 or Williams E supplemented with foetal calf serum, insulin, transferrin, epidermal growth factor and hydrocortisone. The cells in the initial coil cultures had an elongated morphology while those of ductal origin were polyhedral. After 10 days both cultures were composed of polyhedral cells of varying diameter. All these morphological types were of epithelial lineage, as demonstrated by the binding of a monoclonal antibody to cytokeratin, the intermediate filament specific for epithelial cells. Outgrowth from both secretory and reabsorptive epithelia were multilayered, with plentiful desmosomal connections and an underlying basal lamina. Ultrastructural features typical of the epithelial cell types present in intact eccrine sweat glands were absent in a high proportion of the proliferating cells but domes, indicative of transepithelial active ion transport, were present in dense cultures from the reabsorptive duct. Outgrowth was also obtained from the secretory and reabsorptive epithelia of sweat glands from two cystic fibrotic patients. Since the most characteristic malfunction of cystic fibrosis is the impaired ion transport in the eccrine sweat gland, the availability of cultured epithelia should provide a useful model for study of the disease.

Cells, Cultured↗
PubMed1985

Inhibitory effect of adenosine on electrically evoked contractions in the rat vas deferens: calcium dependence.

The inhibitory effect of adenosine on the electrically evoked contractions in the rat prostatic vas deferens was markedly dependent on the calcium concentration in the medium, with adenosine being 20 times more potent at lower calcium levels (1.26 mM vs 3.6 mM). Similar calcium dependence of adenosine inhibition was observed in the presence of a potent nucleoside uptake inhibitor, nitrobenzylthioguanosine (NBTGR), suggesting that this calcium dependence of adenosine inhibition was not secondary to an alteration in adenosine uptake. Furthermore, Bay K8644(methyl-1,4-dihydro-2,6- dimethyl-3-nitro-4-(2-trifluoromethylphenyl)pyridine-5-carboxylate), a dihydropyridine 'calcium entry activator', reduced the potency of adenosine in inhibiting the electrically evoked contractions in a calcium-dependent manner. These results support the notion that adenosine might exert its inhibition on neurotransmission in the prostatic rat vas deferens by decreasing transmembrane calcium currents into the nerve terminals and/or the smooth muscles.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1985

Inhibitory effect of adenosine on electrically evoked contractions in the rat vas deferens: pharmacological characterization.

The inhibitory effects of adenosine as well as its related analogues on the contractile response of the rat vas deferens to field stimulation were compared in the absence and in the presence of nitrobenzylthioguanosine (NBTGR), a potent adenosine uptake inhibitor. In the presence of NBTGR, the order of potency was N6-cyclohexyladenosine (CHA) greater than or equal to L-N6-phenylisopropyladenosine (L-PIA) greater than 2-chloroadenosine greater than D-N6-phenylisopropyladenosine (D-PIA) greater than or equal to adenosine greater than 2'-deoxyadenosine. The inhibitory effect of adenosine but not that of clonidine, beta-endorphin and somatostatin was blocked by 1,3-diethyl-8-phenylxanthine (DPX, pA2 = 7.2), a potent P1-purinergic antagonist. The results suggest that adenosine inhibited the electrically evoked contractions of the rat vas deferens via the activation of the A1 subtype of P1-purinergic receptors.

Adenosine↗
PubMed1985

[(Aminomethyl)arloxy]acetic acid esters. A new class of high-ceiling diuretics. 3. Variation in the bridge between the aromatic rings to complete mapping of the receptor.

Continued structural evaluation of the [(aminomethyl)aryloxy]acetic ester diuretics has produced a series of compounds in which the functional group that bridges the two aromatic rings has been varied. Diuretic screening of these analogues in rats indicates that the keto group can be effectively replaced with an ether or thio ether function with a slight increase in potency, whereas the methylene and sulfoxide linking groups lead to diminished saluretic potency. Replacement with either -SO2-, -COCO-, -CH2O-, -CONH- or direct bond results in a loss of activity. Although the series was designed according to QSAR criteria, the traditional linear free-energy properties of these compounds do not correlate with diuretic potency. However, conformational analysis of the series by potential energy calculations indicates that all active compounds have an accessible conformation that matches the bridge atom-carboxylate distance of the very potent dihydrobenzofuran analogue 56. Conformational calculations of several compounds in which the aminomethyl group was varied suggests that the active conformation is probably a low-energy conformation. Consideration of rotation about the bridge could not distinguish between two possible orientations of the aminomethyl ring in the active conformation. However, there is a quantitative negative linear correlation between diuretic potency and the protrusion into space of the group that bridges the two aromatic rings.

Animals↗
PubMed1985

[(Aminomethyl)aryloxy]acetic acid esters. A new class of high-ceiling diuretics. 4. Substituted 6,7-dichloro-2,3-dihydrobenzofurans derived by ring annelation.

Ring annelation of the [(aminomethyl)aryloxy]acetic acids produced a series of substituted 6,7-dichloro-2,3-dihydrobenzofuran-2-carboxylic acids. Pharmacologic evaluation of these compounds in rats and dogs indicated that several congeners are extremely potent salidiuretics. Clearance and micropuncture experiments in rats for compound 5a confirmed the high-ceiling diuretic profile and demonstrated that 5a has a site of action at the thick ascending limb of Henle's loop.

Acetates↗
PubMed1985

Differences in vitamin B6 status indicator responses between young and middle-aged women fed constant diets with two levels of vitamin B6.

The responses of adult women to two levels of vitamin B6, was conducted with five young and eight middle-aged subjects. A constant diet (2.3-2.4 mg vitamin B6 per day) was fed for four weeks followed by three weeks of the same diet supplemented with 8.0 mg pyridoxine. Plasma pyridoxal 5'-phosphate (PLP), plasma and urinary vitamin B6, and urinary 4-pyridoxic acid (4-PA) were determined. The older women had significantly lower plasma PLP, plasma and urinary vitamin B6 and slightly higher urinary 4-PA values on normal vitamin B6 intakes. With supplementation, only the difference in urinary total vitamin B6 remained significant. Tryptophan load tests revealed no significant between-group differences in xanthurenic acid or kynurenic acid excretion. These results demonstrate an age-related difference in vitamin B6 status indicators in women under controlled dietary intake of vitamin B6.

Adult↗
PubMed1985

Potentiation by cholinoceptor agonists of contractions to field stimulation of rat vas deferens.

Cholinoceptor agonists (arecoline congruent to carbachol greater than acetylcholine greater than pilocarpine) potentiated contractions to field stimulation of rat vas deferens via the activation of an atropine-sensitive muscarinic receptor. The potentiating effect of carbachol was dependent on the level of calcium in the medium, being more potent at higher calcium concentrations. The potentiating effect of carbachol was more pronounced in the epididymal than in the prostatic segment but was not attenuated by prazosin, an alpha 1-adrenoceptor antagonist. Carbachol did not significantly modify the direct contractile effects of noradrenaline nor alter the field-stimulation-evoked release of noradrenaline from the epididymal vas deferens. It is concluded that the potentiating effect of cholinoceptor agonists on the contractions to field stimulation in the rat vas deferens was not a result of an enhancement of adrenergic neurotransmission.

Animals↗
PubMed1985

Interaction of nutrition and infection: effect of vitamin B12 deficiency on resistance to Trypanosoma lewisi.

A metabolic imbalance technique was employed to study vitamin B(12) deficiency in rats infected with Trypanosoma lewisi. Throughout the observational period, animals on the deficient diet had lowered serum vitamin B(12) levels compared with complete and pair-fed animals. The decline in the level of the vitamin, ten days after the initiation of the experiment, continued progressively until the termination of the study. Body weight gains and food consumption in rats on complete, vitamin B(12)-deficient, or pair-fed diets and inoculated with T lewisi showed significant increase over inoculated controls. The rates of body weight and food consumption in vitamin B(12)-deficient animals were significantly less than that of the adequately fed animals.The indices of lowered resistance to infection in the vitamin B(12)-deficient rats were manifoid. Deficient rats suffered earlier and higher parasitemia followed by persistent infection. The delay in the synthesis of the reproductive inhibiting antibody (ablastin) resulted in prolonged variability in the length of the trypomastigotes. Severe depression in the primary and secondary antibody responses (IgG and IgM) to in vivo immunization of sheep erythrocytes was also observed in the deficient animals. In comparison, the level of IgG antibody decreased approximately one fifth the control values.

Animals↗
PubMed1984

Characterization and partial purification of a 5,700 dalton form of substance P-like immunoreactivity from the rat hypothalamus.

Analysis of rat hypothalamic extracts by gel filtration and HPLC revealed the presence of a form of substance P-like immunoreactivity with a molecular weight of approximately 5,700 (6k-SP). 6k-SP is probably an N-terminally extended form of substance P; the peptide may be an intermediate in SP biosynthesis, or may function as a biologically active peptide in its own right.

Animals↗