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Biomedical subjects

C M Lee

Publications and source records attributed to C M Lee.

At least 307 records · Page 17Linked to original sources
PubMed1984

Nucleoside transport. Photoaffinity labelling of high-affinity nitrobenzylthioinosine binding sites in rat and guinea pig lung.

Binding of the potent nucleoside transport inhibitor [3H]nitrobenzylthioinosine to rat and guinea pig lung membranes was investigated. Reversible high-affinity binding was found in both species (apparent KD approximately 0.3nM). Binding was inhibited by nitrobenzylthioguanosine, adenosine and uridine. Dipyridamole was also an effective inhibitor of [3H]nitrobenzylthioinosine binding to guinea pig membranes. In contrast, rat membranes were relatively insensitive to dipyridamole. Exposure of site-bound [3H]nitrobenzylthioinosine to high intensity U.V. light resulted in the photoaffinity labelling of lung proteins with apparent molecular weights similar to that of the human erythrocyte nucleoside transporter (45,000-65,000).

Adenosine↗
PubMed1984

Trichinella spiralis: immunization of rats with an antigen fraction enriched for allergenicity.

Trichinella spiralis whole muscle larval extract was fractionated by gel filtration and anion-exchange chromatography, and the protein fractions were assayed for allergenicity by a footpad-swelling test in mice; IgE antibody levels in rats immunized with the fractions were determined by passive cutaneous anaphylaxis test in rats. By these methods, an allergenic fraction from T. spiralis was isolated. The fraction, F1-b, was shown to be monodisperse by analysis with SDS-PAGE, IEP, and isoelectric focusing, indicating that it is a single protein moiety with a molecular weight of approximately 45,000 and a pI of approximately 5.1. The Schiff-periodate test showed F1-b to be a glycoprotein. Rats immunized with F1-b had significantly fewer intestinal worms than did nonimmunized controls at 24 hr and 7 days after oral challenge with T. spiralis larvae.

Animals↗
PubMed1984

Trypanosoma lewisi: pyruvate and transketolase activity in normal and thiamine deficient rats.

Transketolase and pyruvate changes were studied in rats infected with Trypanosoma lewisi and fed complete, thiamine-deficient and pair-fed control diets. Regardless of the dietary group, marked increases in pyruvate levels were observed in the infected animals. There were no significant differences in erythrocyte transketolase activity of rats given a full complement diet. Significant decreases, however, were observed in the transketolase activity of pair-fed and thiamine deficient rats. The greater decreases occurred in the infected animals.

Animals↗
PubMed1984

[(Aminomethyl)aryloxy]acetic acid esters. A new class of high-ceiling diuretics. 1. Effects of nitrogen and aromatic nuclear substitution.

A series of Mannich bases and aminomethyl derivatives of ethyl [2,3-dichloro-4-(4-hydroxybenzoyl)phenoxy]acetate were synthesized and tested for saluretic and diuretic activities. The effects of nitrogen and aromatic nuclear substitution, reorientation of the aminomethyl group relative to that of the phenolic hydroxyl group, and replacement of either the phenolic hydroxyl or the aminomethyl group by other functional groups are described. Ethyl [2,3-dichloro-4-[3-(aminomethyl)-4-hydroxybenzoyl]phenoxy]acetate (27) was found to be a very potent, high-ceiling diuretic.

Administration, Oral↗
PubMed1984

[(Aminomethyl)aryloxy]acetic acid esters. A new class of high-ceiling diuretics. 2. Modifications of the oxyacetic side chain.

The discovery of high-ceiling natriuretic activity from a series of aminomethyl derivatives of ethyl [2,3-dichloro-4-(4-hydroxybenzoyl)phenoxy]acetate prompted our continued investigation of this new class of (aryloxy)acetic acid diuretics. Systematic alteration of the oxyacetic side chain has shown that the carboxylic acid function is the active species in vivo and that the ethyl ester group serves as a prodrug to enhance oral absorption. Side-chain functional groups that are incapable of generating the carboxylic acid in vivo failed to impart diuretic activity to the target compounds. Additional side-chain modifications including homologation, methyl substitution, and heteroatom replacement are also described. Ring annelation of the oxyacetic side chain to a dihydrobenzofuran-2-carboxylic acid produced compound 32, which displayed the highest level of saluretic activity for this series.

Administration, Oral↗
PubMed1984

Biochemical and ultrastructural studies of human eccrine sweat glands isolated by shearing and maintained for seven days.

A new method of isolating human eccrine sweat glands by the repeated dissection of skin biopsies with scissors is described. The success of the technique is attributed to a potential line of weakness between the investing capsule and the surrounding connective tissue, which parts under shear forces. The yield is 20-50 glands per biopsy (5 cm X 0.5 cm). The glands are judged to be viable by: (i) light and electron microscopy; (ii) ATP, ADP and AMP contents of 81.0 +/- 12.7, 13.8 +/- 3.3 and 3.8 +/- 1.0 pmol/gland, respectively (mean +/- S.E.M.), which gave an energy charge of 0.90; (iii) the 28-fold rise in cyclic GMP content and the sevenfold rise in cyclic AMP content effected by treatment for 2 min with 10(-5) M-acetylcholine and for 10 min with 10(-5) M-isoprenaline, respectively; (iv) the rate of [3H]leucine uptake into protein; and (v) the concentration of Neutral Red by the collecting duct. Glands were maintained for 7 days on polycarbonate filters floating on RPMI 1640 tissue-culture medium. After this time the ATP, ADP and AMP contents were 63.2 +/- 7.3, 8.5 +/- 2.2 and 3.5 +/- 0.8 pmol/gland, respectively (mean +/- S.E.M.), which gave an energy charge of 0.90. During maintenance a dilatation of the intercellular spaces developed in both secretory coil and collecting duct. Following maintenance there was a significant rise in the rate of [3H]leucine uptake into protein. Maintained glands demonstrated a fivefold greater accumulation of cyclic AMP in response to isoprenaline than did freshly isolated glands, but there was no comparable maintenance hypersensitivity of cyclic GMP to acetylcholine. This pattern of adrenergic, but not cholinergic, maintenance hypersensitivity matches the known lack of denervation hypersensitivity of human eccrine sweat glands to acetylcholine in vivo.

Adenosine Diphosphate↗
PubMed1984

Trypanosoma lewisi: in vitro oxygen uptake by parasites grown in albino and black rats.

Oxygen consumption of Trypanosoma lewisi grown in albino and black rats was measured by the direct method of Warburg. Respiration rates in buffered Ringer's solution, with and without glucose and in normal serum from the respective hosts, were determined for T lewisi grown in albino and black rats. Significantly higher respiratory rates were obtained for trypanosomes grown in albino hosts: 31 percent higher in buffered Ringer's solution with glucose and 26 percent higher in homologous serum.In this study, in which the development of the parasitemia was observed for 27 days, T lewisi populations were higher in albino rats than in black rats.

Animals↗
PubMed1984

[Spoilage microorganisms encountered in ultra-high temperature processed milk].

40 strains of aerobic or facultative anaerobic microorganisms were isolated from a total of 37 spoiled ultra high temperature processed milk. 13 of them were identified as the genus Bacillus. They were 6 B. cereus, 5 B. licheniformis, 1 B. brevis and 1 B. pumilus. The other 27 strains were nonsporeforming microorganisms, which included 5 yeasts, 2 Pseudomonas sp., 3 Streptococcus sp., 12 Lactobacillus sp., 1 Shigella sp., 1 Aeromonas sp. and 3 Micrococcus sp. Results indicate that the spoilage of milk sample was caused mainly by the contamination during the filling operation. The Bacillus strains isolated were mesophilic or thermophilic, and some of them, were also psychrotrophic.

Animals↗
PubMed1983

Recognition sites for norepinephrine uptake: regulation by neurotransmitter.

Recognition sites for the uptake of norepinephrine on adrenergic neurons in the brain and periphery were labeled with [3H]desipramine. The number of these uptake sites varied with the concentration of transmitter; depletion of norepinephrine with reserpine reduced the number of uptake sites, whereas increasing the concentration of norepinephrine induced by treatment with monoamine oxidase inhibitors raised the number of binding sites. These dynamic alterations in norepinephrine uptake recognition sites may regulate synaptic function homeostatically, providing less inactivation of reuptake when the synaptic concentration of the transmitter is low and increased inactivation when it is high.

Animals↗
PubMed1983

Interaction of nutrition and infection: effect of zinc deficiency on resistance to Trypanosoma musculi.

1. Zinc deficiency was studied in mice infected with Trypanosoma musculi. 2. In all dietary groups, the infected animals consumed more food and gained more weight than the uninfected controls. 3. In all studies, at the peak of parasitemia, the zinc-deficient animals showed three times the number of trypanosomes as that of the complete and pair-fed mice. 4. The average coefficients of variation in body lengths of T.musculi cells indicated that the formation of the reproductive-inhibiting antibody (ablastin) occurred later in zinc-deficient animals compared to animals fed complete diets. The degree and duration of parasitemia in the zinc-deficient animals indicated a delay in the synthesis of the terminal lytic antibody. 5. Irrespective of diets, severe depression in the primary and secondary antibody responses to in vivo immunization of sheep erythrocytes was observed in infected animals over non-infected controls.

Animals↗
PubMed1983

Rat liver glucose-6-phosphate dehydrogenase isozymes: influence of infection with Trypanosoma.

Glucose-6-phosphate dehydrogenase (G6PD) changes were studied in livers of rats inoculated with Trypanosoma lewisi, Trypanosoma rhodesiense, Trypanosoma congolense and Trypanosoma brucei. Marked increases in G6PD were directly related to the degree of parasitemia. No essential differences in G6PD levels were seen in animals inoculated with physiological saline when compared with uninoculated controls. Elevation of G6PD was observed only from day 10 to 20 in rats inoculated with T. lewisi. After day 20, the G6PD levels were not statistically significant from those of uninoculated controls. Liver G6PD levels were increased as early as day 3 post-inoculation and continued up to the time of death in rats inoculated with T. brucei, T. rhodesiense and T. congolense.

Animals↗
PubMed1983

A temperature-sensitive mutant of Newcastle disease virus which is affected in both haemagglutinin-neuraminidase and matrix proteins.

Virions prepared from a non-revertible temperature-sensitive (ts) mutant (ts53) of Newcastle disease virus (NDV) grown in ovo at the permissive temperature (34 degrees C) possessed thermolabile haemagglutination and neuraminidase activities compared with parental (ts+) virions. Purified haemagglutinin-neuraminidase (HN) protein from ts53 virions was also more thermolabile than ts+ HN protein. SDS-PAGE analysis of [3H]leucine pulse- and pulse/chase-labelled NDV proteins synthesized in chick embryo fibroblasts following infection with ts+ and ts53 virus revealed that ts53 matrix (M) protein was unstable and disappeared during chase incubations only at the non-permissive temperature (42 degrees C). The non-revertibility of the ts53 mutant may indicate that it is a double mutant affected in both HN and M genes; alternatively this mutant may only be affected in the HN gene, the close physical association of the thermolabile HN with the M protein during virus maturation resulting in the lack of protection of the M protein from the action of cellular proteases at the non-permissive temperature.

Cycloheximide↗
PubMed1983

3h-substance P binding to salivary gland membranes. Regulation by guanyl nucleotides and divalent cations.

With appropriate measures to protect 3H-substance P (3H-SP) from proteolytic degradation and from nonspecific adsorption to glass-fiber filters, we have been able to demonstrate reliably a high-affinity specific binding of 3H-SP to rat submaxillary/sublingual gland membranes with a KD of 1 nM and Bmax of 6 pmoles/g of tissue. The relative potencies of various SP fragments and related analogues in reducing 3H-SP binding parallel their potencies in stimulating phosphatidylinositol turnover, amylase release, and salivation, thus supporting an association of the observed 3H-SP binding site with the physiological SP receptors in this tissue. This binding is selectively stimulated by some divalent cations (Mn2+ greater than Mg2+ greater than Ca2+) but inhibited by several guanyl nucleotides, suggesting a possible linkage to adenylate cyclase. However, no effect of SP on either the basal or the norepinephrine-stimulated adenylate cyclase activity could be demonstrated in salivary gland homogenates.

Adenylyl Cyclases↗
PubMed1983

The mechanism of natural binding of bacteria to human lymphocyte subpopulations.

Some bacteria bind naturally to human lymphocyte subpopulations. Here we investigated the nature of the interacting factors" on bacterial cells and on lymphocytes. First, surface Ig was not involved in the binding of B. melitensis to B cells, since capping of surface Ig did not affect the binding of this bacteria. We put forward the hypothesis that the binding is due to an interaction between a protein (probably a lectin) on the lymphocyte surface and a carbohydrate on the bacteria. The following observations were consistent with this hypothesis: (1) the binding of B. melitensis to B cells was prevented by alpha-methyl-D-mannoside (alpha-MM) but not by other sugars; (2) the binding of B. melitensis to B cells was prevented by pretreatment of the peripheral blood lymphocytes (PBL) with 257 mM of alpha-MM but pretreatment of the bacteria had no effect; (2) an Escherichia coli mutant (strain 2023) which binds to B cells and part of the T cells was also agglutinated by Concanavalin A (Con A) but the nonbinding parental strain was not; the binding of this mutant to B cells was also inhibited by 257 mM of alpha-MM; (4) bacteria that bind to human lymphocytes were agglutinated at high titers by various plant lectins while those that do not bind were not agglutinated or were agglutinated only at low titers; (5) bacteria that bind to B cells as well as those that bind to B and T cells all were agglutinated by Con A, Lens culinaris agglutinin and Pisum sativum agglutinin, whose carbohydrate specificities were alpha-D-mannosyl- and alpha-D-glucosyl-residues; (6) the "receptors" on lymphocytes but not those on bacteria were sensitive to pronase digestion; and (7) bacteria still bound after being heated at 121 degrees C or being fixed with formaldehyde. Thus, we suggest that one of the mechanisms by which bacteria bind to lymphocytes may be by the interaction between a lectin on the lymphocyte and a carbohydrate on the bacteria.

Agglutination↗
PubMed1983

Immunobiology of trichinosis.

Trichinosis is world-wide in distribution, occurring in tropical, temperate, and polar regions. Although incidence of the disease appears to be declining in most regions, it is still widely distributed in Europe and is increasing in many parts of Africa. In recent years, the incidence of trichinosis in the United States also has increased. This article reviews the nature of immunity to trichinosis.

Animals↗