PubMed Health⌕ Search

Biomedical subjects

C W Lee

Publications and source records attributed to C W Lee.

At least 19 recordsLinked to original sources
PubMed1992

Autoimmune progesterone dermatitis.

A 35-year-old woman had recurrent urticarial erythemas on her trunk and extremities for 3 years. The eruptions appeared regularly 3 to 5 days prior to menstruation and persisted for several days. The patient showed a positive skin test response to progesterone and had circulating antiprogesterone IgG antibodies. A speculative concept of the possible autoimmune damage to the ovary, the major organ producing progesterone, is discussed.

Adult↗
PubMed1992

Epidermolysis bullosa acquisita presenting with localized facial blisters.

A 44-year-old woman presented with blisters on her face of 1-month's duration. A biopsy showed a subepidermal bulla with a dermal infiltrate of inflammatory cells and thick linear deposits of immunoreactants along the dermo-epidermal junction. Using Western immunoblots, the patient's IgG antibody was found to recognize type VII procollagen. Moderate doses of oral prednisolone resulted in a complete remission, without a recurrence for more than 3 years.

Adult↗
PubMed1991

Inhibition by pertussis toxin of the activation of Na(+)-dependent uridine transport in dimethyl-sulphoxide-induced HL-60 leukaemia cells.

The effects of pertussis toxin on the Na(+)-dependent transport of uridine were studied in HL-60 leukaemia cells induced to differentiate along the granulocytic or monocytic pathways by dimethyl sulphoxide (DMSO) or phorbol 12-myristate 13-acetate (PMA) respectively. Pertussis toxin at 50 ng/ml completely inhibited the activation of Na(+)-dependent uridine transport and consequently prevented the formation of intracellular pools of free uridine which occurs in HL-60 cells induced to differentiate by DMSO. The inhibition of Na(+)-dependent uridine transport by pertussis toxin in cells exposed to DMSO was associated with a 14-fold decrease in affinity, with no change in Vmax. Pertussis toxin, however, had no effect on Na(+)-dependent uridine transport in PMA-induced HL-60 cells. Furthermore, 500 ng of cholera toxin/ml had no effect on the Na(+)-dependent uptake of uridine in DMSO-treated HL-60 cells. These results suggest that the activation of the Na(+)-dependent transport of uridine in HL-60 cells induced to differentiate along the granulocytic pathway by DMSO is coupled to a pertussis-toxin-sensitive guanine-nucleotide binding protein (G-protein).

Biological Transport↗
PubMed1991

Induction of the differentiation of HL-60 cells by phorbol 12-myristate 13-acetate activates a Na(+)-dependent uridine-transport system. Involvement of protein kinase C.

The Na(+)-dependent transport and facilitated diffusion of uridine were measured after differentiation of HL-60 leukaemia cells along the monocytic pathway by phorbol 12-myristate 13-acetate (PMA). PMA (200 ng/ml) caused a marked increase in Na(+)-dependent uridine transport within 48 h of exposure that was attributable to an increase in transport affinity (apparent Km values of 1.15 +/- 0.22 and 44 +/- 4.4 microM for PMA-induced and uninduced cells respectively), with no change in Vmax. (0.15 +/- 0.02 and 0.13 +/- 0.01 pmol/s per microliter of cell water for PMA-induced and uninduced cells respectively). A corresponding rapid decrease in both the rate of facilitated diffusion and the formation of uracil nucleotides occurred in PMA-induced cells. As a consequence of these changes, intracellular pools of uridine 3-4-fold greater than those in the medium were generated. A similar increase in Na(+)-dependent transport of adenosine, inosine, guanosine, thymidine and cytidine (Km values of 1-4 microM) was observed. The effects of PMA on the activation of the Na(+)-dependent uridine transporter were inhibited by staurosporine, suggesting the involvement of protein kinase C. The findings indicate that a change in the balance of the cellular mechanisms employed for nucleoside transport occurs during the monocytic differentiation of HL-60 leukaemia cells.

Alkaloids↗
PubMed1991

Effects of uridine on the growth and differentiation of HL-60 leukemia cells.

HL-60 leukemia cells, induced to differentiate, activate a Na(+)-dependent nucleoside transport system, concomitant with a reduction in the nitrobenzylthioinosine (NBMPR)-sensitive facilitated transport of nucleosides. The consequence of these changes lead to the formation of intracellular pools of uridine. To examine the possible role of accumulated uridine in the commitment of HL-60 leukemia cells to undergo maturation, the effects of uridine on the growth and differentiation of HL-60 cells were monitored. Uridine at millimolar levels caused a concentration-dependent inhibition of cellular growth, resulting in the accumulation of cells in the G2/M phases of the cell cycle, phenomena that preceded the formation of differentiated cells. These effects of uridine were reduced by 10 microM NBMPR, an inhibitor of the facilitated transport of nucleosides. The effects of 24 mM uridine on growth and differentiation of HL-60 cells were also prevented by 5 mM inosine, and partially prevented by either 2 mM hypoxanthine or 20 microM adenosine. Pretreatment of HL-60 cells with 24 mM uridine for 6 days, followed by a 2 h exposure to TPA, resulted in the rapid attachment of cells to the tissue culture dish, and the extension of long processes. Although the concentrations of uridine required for the above effects are greater than those achieved during differentiation, these observations suggest that uridine may play a role in regulating the maturation process.

Cell Differentiation↗
PubMed1991

Cardiovascular collapse following orthoclone OKT3 administration: a case report.

Orthoclone OKT3 has been described to have significant adverse effects on the cardiovascular system, including pulmonary edema, angina, dysrhythmias, hypertension, and hypotension, usually following the first or second doses of the drug. We describe a case of cardiopulmonary arrest in a patient 1 minute after the initial injection of OKT3. Two subsequent doses were successfully administered with the guidance of hemodynamic monitoring, which showed profound, immediate effects of OKT3 on the cardiovascular system. Potential mechanisms of these effects are discussed.

Antibodies, Monoclonal↗
PubMed1991

Granulomatous tissue reaction following cosmetic eyebrow tattooing.

We report a case of epithelioid granuloma which occurred at the site of a previous cosmetic eyebrow tattooing. A biopsy specimen showed the organized appearance of epithelioid cell granulomas containing little pigment as well as occasional giant cells, mainly of Langhans' type, thus showing the characteristic features of granulomatous hypersensitivity. With the use of energy dispersive X-ray microanalysis and inductively coupled plasma spectrometry, the presence of copper, iron, cobalt, and chromium was demonstrated.

Coloring Agents↗
PubMed1990

Transport characteristics of renal brush border Na(+)- and K(+)-dependent uridine carriers.

The uptake of uridine into rat renal brush-border membrane vesicles is mediated by Na(+)- and K(+)-dependent concentrative transport processes. At a 100 mM extravesicular cation concentration the apparent Km values were 9.7 +/- 4.2 and 28 +/- 5 microM, and Vmax values were 28 +/- 4 and 7 +/- 1 pmol.mg protein-1.s-1 for the Na(+)- and K(+)-dependent systems, respectively. Uracil, D-ribose, and D-glucose failed to inhibit the uptake processes, indicating that these carriers are specific for nucleosides. Other purines and pyrimidines inhibited uridine uptake competitively, although these two transport systems seem to favor adenosine and pyrimidines as permeants. Evidence is also given that transport is rheogenic, involving a net transfer of positive charge. The Na+:uridine and K+:uridine coupling stoichiometry was found to be 1:1 and 3:2, respectively. Both systems can also be driven by an anion gradient with apparent NO3- affinity (KNO3-) values of 42 +/- 13 and 163 +/- 54 mM for Na(+)- and K(+)-dependent systems, respectively.

Animals↗
PubMed1990

A new staining solution for the morphological studies of fungi and Prototheca.

A new staining solution named "PHOL" is described for studying the morphology of clinical and environmental isolates of fungi and Prototheca. In total 69 isolates were used for assessing the efficacy of this newly formulated stain. The solution has shown good ability to stain all 62 isolates of fungi and 7 of Prototheca, and thus helped in the identification of the organisms. The new solution has the potential to stain the young as well as old isolates of fungi and Prototheca. It is emphasized that a wider application of this newly introduced inexpensive and safe staining solution will help the mycologists to study the morphological characteristics of yeast, molds, and Prototheca obtained from man, animals and environment.

Fungi↗
PubMed1989

Characterization of the L lambda phase in trehalose-stabilized dry membranes by solid-state NMR and X-ray diffraction.

Solid-state nuclear magnetic resonance (NMR) spectroscopy and X-ray powder diffraction were used to investigate the mechanism of trehalose (TRE) stabilization of lipid bilayers. Calorimetric investigation of dry TRE-stabilized bilayers reveals a first-order phase transition (L kappa----L lambda) at temperatures similar to the L beta'----(P beta')----L alpha transition of hydrated lipid bilayers. X-ray diffraction studies show that dry mixtures of TRE and 1,2-dipalmitoyl-sn-phosphatidylcholine (DPPC) have a lamellar structure with excess crystalline TRE being present. The L kappa phase shows typical gel-phase X-ray diffraction patterns. In contrast, the L lambda-phase diffraction patterns indicate disordered hydrocarbon chains. 2H NMR of specifically 2H chain-labeled DPPC confirmed that the acyl chains are disordered in the L lambda phase over their entire lengths. 2H spectra of the choline headgroup show hindered molecular motions as compared to dry DPPC alone, and 13C spectra of the sn-2-carbonyl show rigid lattice powder patterns indicating very little motion at the headgroup and interfacial regions. Thus, the sugar interacts extensively with the hydrophilic regions of the lipid, from the choline and the phosphate moieties in the headgroup to the glycerol and carbonyls in the interfacial region. We postulate that the sugar and the lipid form an extensive hydrogen-bonded network with the sugar acting as a spacer to expand the distance between lipids in the bilayer. The fluidity of the hydrophobic region in the L lambda phase together with the bilayer stabilization at the headgroup contributes to membrane viability in anhydrobiotic organisms.

Cell Survival↗
PubMed1989

Two-dimensional 1H/13C heteronuclear chemical shift correlation spectroscopy of lipid bilayers.

Using solid-state magic angle spinning nuclear magnetic resonance (NMR) techniques, we have obtained two-dimensional (2D), 1H/13C chemical shift-correlated spectra of liquid crystalline 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) bilayers in 30 wt% PO4/D2O buffer. Linewidths in both the 13C and the 1H dimensions were less than 0.3 ppm wide. The 2D spectrum consists of chemical shift correlations between all resolvable, directly bonded 13C-1H pairs and exhibits considerably greater spectral dispersion than either ID 1H or 13C MAS spectra. This approach promises to be an important tool in structural studies of biological membranes.

Carbon Isotopes↗