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D Lee

Publications and source records attributed to D Lee.

At least 19 recordsLinked to original sources
PubMed1995

The Arabidopsis thaliana 4-coumarate:CoA ligase (4CL) gene: stress and developmentally regulated expression and nucleotide sequence of its cDNA.

An Arabidopsis cDNA clone encoding 4-coumarate:CoA ligase (4CL), a key enzyme of phenylpropanoid metabolism, was identified and sequenced. The predicted amino acid sequence is similar to those of other cloned 4CL genes. Southern blot analysis indicated that 4CL is single-copy gene in Arabidopsis. Northern blots showed that 4CL expression was activated early during seedling development. The onset of 4CL expression was correlated with the onset of lignin deposition in cotyledons and roots 2-3 days after germination. The timing of the expression of a parsley 4CL1-GUS fusion in transgenic Arabidopsis seedlings was examined in parallel and was very similar to that of endogenous 4CL. In mature plants, highest 4CL expression was observed in bolting stems, where relatively large amounts of lignin accumulate. Both 4CL and 4CL1-GUS mRNA accumulation was strongly and transiently activated by wounding of mature Arabidopsis leaves. 4CL expression was specifically activated within 6 h after infiltration of Arabidopsis ecotype Columbia leaves with a Pseudomonas syringae pv. maculicola strain harboring the bacterial avirulence gene avrB, which causes in incompatible interaction. The timing of 4CL activation was identical to the previously observed activation of PAL gene expression in this interaction. No activation of 4CL expression was observed in a compatible interaction caused by a Pseudomonas syringae pv. maculicola strain without avrB.

Amino Acid Sequence↗
PubMed1995

Glucocorticoids inhibit D1B, but not D2, receptor-mediated effects on hypothalamic atrial natriuretic factor neurons.

Recent evidence suggests that ANF neurons of the hypothalamus are dopamine sensitive, and the catecholamine may exert a direct stimulatory or inhibitory effect on the neurons mediated through D1 or D2 receptors, respectively, in a manner related to the differential dopamine binding sensitivity of the two receptor subtypes. Employing well characterized ANF RIA and colorimetric Northern blot analysis with synthetic oligonucleotide probes complementary to pro-ANF messenger RNA (mRNA), we report here the effect of dexamethasone (DM), a potent synthetic glucocorticoid, on DA-stimulated ANF neurons in long term primary cultures of neonatal rat hypothalamic cells. Although DM alone did not affect basal secretion of immunoreactive ANF, it approximately halved immunoreactive ANF secretion induced by D1 agonist, SKF38393 (P < 0.01). The effect of DM was both time dependent and dose related, with an EC50 of 0.1 nM; it was blocked by 100 nM RU38486 (P < 0.05), a glucocorticoid receptor antagonist, but not by 100 nM RU28318, a mineralocorticoid receptor antagonist. In addition, the effect of DM was mimicked by corticosterone (EC50, 10 nM), but not deoxycorticosterone. The increased expression of pro-ANF mRNA signal induced by the D1 agonist in culture was suppressed by DM in a similar manner. In contrast, DM did not modulate ANF production and secretion induced by D2 agonist, quinpirole. Furthermore, reverse transcription-polymerase chain reaction demonstrated that D1B, but not D2, receptor mRNA expression was selectively suppressed by glucocorticoids. Thus, we conclude that in monolayer cultures of rat hypothalamic neurons, glucocorticoids differentially modulate dopamine receptor-induced responsiveness of ANF neurons by down-regulating D1B, but not D2, receptor-mediated changes. Hence, in severe stress, high levels of circulating glucocorticoids may negate the D1B-induced stimulatory response but allow dopamine to suppress the function of hypothalamic ANF neurons through D2 receptor activation.

Animals↗
PubMed1995

Case report: coincident granular cell tumour of the breast with invasive ductal carcinoma.

Granular cell tumours of the breast are rare lesions which are almost always benign. They are of interest because their clinical, radiological and pathological appearances often closely resemble those of malignancy. A case is described in which screening mammography in an asymptomatic woman led to the diagnosis of simultaneous invasive intraductal carcinoma in one breast and benign granular cell tumour in the other. Granular cell tumour of the breast coincident with other breast tumours is very rarely described and an association with breast carcinoma is unknown.

Breast Neoplasms↗
PubMed1995

Differential control of type-I iodothyronine deiodinase expression by the activation of the cyclic AMP and phosphoinositol signalling pathways in cultured human thyrocytes.

The effects of TSH and the activation of the cyclic AMP (cAMP) and Ca(2+)-phosphatidylinositol (Ca(2+)-PI) cascades on the activity and expression of the selenoenzyme thyroidal type-I iodothyronine deiodinase (ID-I) have been studied using human thyrocytes grown in primary culture. Stimulation of ID-I activity and expression was obtained with TSH and an analogue of cAMP, 8-bromo-cAMP. In the presence or absence of TSH, the addition of the phorbol ester, phorbol 12-myristate 13-acetate (PMA) together with the calcium ionophore A23187, caused a decrease in ID-I activity; a decrease in ID-I expression was also observed as assessed by cell labelling with [75Se]selenite. PMA alone had no effect on ID-I activity in the presence or absence of TSH. A23187 alone produced a small but significant reduction in ID-I activity, but only in TSH-stimulated cells. These data provide evidence that the expression of thyroidal ID-I is negatively regulated by the Ca(2+)-PI cascade, and positively regulated by the cAMP cascade.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1995

Design and development of external prostheses and their function.

This article describes current techniques and materials used in the prosthetic rehabilitation of disfigured patients. The types of patients helped by external prostheses, the importance of accurate sculpting and tinting of prosthetic devices, the type of adhesives, and the new technique of osseous integration for external fixation of appliances are also reviewed in this article.

Ear↗
PubMed1995

Thiopurine methyltransferase pharmacogenetics. Cloning of human liver cDNA and a processed pseudogene on human chromosome 18q21.1.

Thiopurine methyltransferase (TPMT) is a genetically polymorphic enzyme that catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine. This genetic polymorphism is an important factor responsible for individual variation in thiopurine drug response. A cDNA for TPMT has been cloned from T84 human colon carcinoma cells. Northern blot analysis of multiple human tissues was performed with the T84 human colon carcinoma TPMT cDNA open reading frame (ORF) as a probe as one step toward understanding the molecular basis for the TPMT genetic polymorphism. Three mRNA species (approximately 1.4, 2.0, and 3.6 kb in length) were present in all tissues studied, including liver. However, none of these mRNAs matched the length of the 2.7 kb T84 TPMT cDNA. Therefore, it was important to clone a TPMT cDNA from a human drug-metabolizing organ such as the liver to determine whether its sequence matched that of the cDNA cloned from the T84 cell line. A human liver cDNA library was screened with the T84 TPMT cDNA ORF as a probe, and a 1.8 kb cDNA was isolated with a coding region sequence identical to that of the T84 TPMT cDNA. The TPMT cDNA ORF was then used to screen a human lymphocytes genomic DNA library in an attempt to clone the TPMT gene(s) in humans. Three intronless clones were isolated with identical ORF sequences that were 96% identical to that of the TPMT cDNA, but which contained multiple nucleotide substitutions and one deletion. The 3'- and 5'-flanking regions of one of the genomic DNA clones were sequenced.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1994

Glucocorticoids potentiate the adenylyl cyclase-cAMP system mediated immunoreactive beta-endorphin production and secretion from hypothalamic neurons in culture.

Beta-endorphin(beta EP)1-31, a potent opioid peptide of proopiomelanocortin (POMC) derivatives, is produced and released from neurons at arcuate nuclei of the rat hypothalamus. Although dexamethasone (DM) suppresses the production and secretion of POMC related peptides from rat pituitary corticotrophs, the effect of glucocorticoids on the function of hypothalamic beta EP neurons remains unclear. Employing long term monolayer cultures of neonatal rat hypothalamic cells, we report here that 4 day treatment with 10 microM of forskolin increased ir-beta EP levels in cell content and culture media by approximately 1.7 (P < 0.05) and 4.1 times (P < 0.01) above vehicle treated control cultures (mean +/- S.E.M., 47.3 +/- 2.6 pg/well and 40.4 +/- 3.0 pg/well; n = 3) respectively. Although 4 day treatment with DM alone had little effect on the release and the cell content of ir-beta EP, it significantly enhanced forskolin-induced elevation of ir-beta EP levels in cell content and in culture media. The effect of DM was dose-related and time-dependent, with an EC50 of about 1 nM; at this concentration DM enhanced ir-beta EP secretion about 2.1 times (P < 0.01) above that induced by 10 microM of forskolin alone. Furthermore, the potentiating effect of DM was specifically suppressed by 100 nM of RU38486 (P < 0.01), a glucocorticoid receptor antagonist, but not by an equivalent dose of RU28318, a mineralocorticoid receptor antagonist. In addition, Northern blot analysis showed that forskolin (10 microM) increased the abundance of POMC mRNA 1.4 fold above that of vehicle treated control cultures. Whereas by itself, DM (10 nM) had little effect on the level of POMC mRNA, it enhanced forskolin-stimulated increase of the abundance of POMC mRNA approximately 2.6 times. Moreover, DM also augmented 1.6 times (P < 0.05) forskolin-induced but not 3-isobutyl-1-methylxanthine (IBMX)-induced increase of cAMP production (5.5 +/- 0.4 pmol/well; mean +/- S.E.M., n = 3) in the cultures. Taken together, our findings suggest that in contrast to the inhibitory effect on pituitary corticotrophs, glucocorticoids enhance the production and secretion of beta EP from rat hypothalamic neurons by facilitating the stimulatory effect mediated, in part, through the adenylyl cyclase-cAMP system.

1-Methyl-3-isobutylxanthine↗
PubMed1994

D2 receptors mediate dopamine suppression of irANF release and pro-ANF mRNA expression of rat hypothalamic neurons in culture.

Although N-terminal truncated forms of atrial natriuretic factor (ANF) are produced and released from rat hypothalamic neurons, the intrahypothalamic regulation of these processes remains unclear. Employing a well-characterized hypothalamic cell culture system, we report here that dopamine, mediating through D2 receptors, inhibits the synthesis and release of ANF. In long-term cultures of hypothalamic neurons, daily treatment for 4 days with quinpirole, a D2 agonist, significantly suppressed the basal irANF release in a time-related and a dose-dependent manner. The ED50 and Emax of the drugs were 9.1 x 10(-8) M and 10(-5) M, respectively. This effect of quinpirole was mimicked by 10(-7) M of dopamine, a physiological ligand for D2 receptor. Furthermore, the suppressing effects of both quinpirole and dopamine were abolished by sulpiride, a D2 antagonist. Whereas 10(-6) M of forskolin treatment consistently enhanced the release of irANF through activating the adenylyl cyclase-cAMP system, this stimulatory effect was suppressed by quinpirole in a dose-related manner. In addition, the application of pertussis toxin, a bacterial toxin which inactivated G1 protein activity, reversed the suppressing effect of quinpirole or dopamine on irANF release. These immunoassay findings were accompanied by corresponding changes in the abundance of pro-ANF mRNA in the cultures as determined by colorimetric Northern blot analysis. By combining the techniques of in situ hybridization and immunocytochemistry, the mRNA of D2 receptor was colocalized with irANF at a single cell level by double fluorescent staining.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

The adenylyl cyclase-cyclic AMP system modulates morphological and functional development of hypothalamic beta-endorphin neurons in culture.

In rats, opioidergic beta-endorphin (beta EP1-31) is produced and released from neurons of arcuate nuclei in the hypothalamus. Although the neuropeptide has been implicated in sexual maturation and stress-induced reproductive dysfunction, the intra-hypothalamic regulation of beta EP neurons remains unclear. Employing long-term monolayer cultures of neonatal rat hypothalamic cells, we report here that 4 days of treatment with 10 microM forskolin increased approximately 3-fold (P < 0.01) the proportion of immunoreactive (ir)-beta EP positive neurons bearing neurites. In addition, treatment of forskolin also enhanced ir-beta EP release (634 +/- 59 pg/well; mean +/- SE, n = 4, P < 0.01) by 14-fold and ir-beta EP content (119 +/- 13 pg/well; P < 0.01) by 2-fold above that of vehicle-treated cultures; in both instances, the EC50 and the Emax of forskolin were approximately 10 microM and 100 microM, respectively. The forskolin-stimulated release of ir-beta EP was mimicked by cholera toxin and (Bu)2cAMP treatment in a dose-related manner, but not by pertussis toxin. Although by itself 3-isobutyl-1-methyl-xanthine (100 microM) only doubled ir-beta EP secretion, it markedly potentiated the stimulatory effect of forskolin. This forskolin-induced stimulation was reversible and in cultures re-exposed to the same drug within the first 24 h period, there was a marked increase in the stimulated release of ir-beta EP (P < 0.05); re-challenge of forskolin at later stages, however, induced a smaller but significant secretion of ir-beta EP (P < 0.01) compared to that of vehicle-treated control cultures. Sephadex G-50 gel chromatographic profile of the media prepared from forskolin-treated cultures revealed a major ir-beta EP peak of 3 K M(r). High-performance liquid chromatography analysis showed that ir-beta EP of the 3 K M(r) species was eluted with a retention time similar to that of synthetic rat beta EP1-31. We thus conclude that the adenylyl cyclase-cAMP system plays an important role in the modulation of beta EP1-31 production and release from hypothalamic beta EP neurons in culture. Furthermore, the functional responsiveness and the morphological development of these neurons are affected, at least in part, by the intrinsic activity of the adenylyl cyclase-cAMP system.

1-Methyl-3-isobutylxanthine↗
PubMed1992

Marked reduction of high density lipoprotein cholesterol in mice genetically modified to lack apolipoprotein A-I.

Atherosclerosis is a major cause of morbidity and mortality in developed countries. In humans the risk of atherosclerosis is inversely correlated with plasma levels of high density lipoprotein (HDL). As a step in determining whether the experimental reduction of plasma HDL level will increase susceptibility to atherosclerosis, we have used gene targeting in embryonic stem cells to produce mice lacking apolipoprotein A-I, the major protein component of HDL particles. Mice homozygous for the disrupted gene have no plasma apolipoprotein A-I detectable by double immunodiffusion; their total plasma cholesterol and HDL-cholesterol levels after overnight fasting are reduced to about one-third and one-fifth of normal levels, and they are grossly deficient in alpha-migrating HDL particles.

Animals↗
PubMed1992

Race/ethnicity and other risk factors for gestational diabetes.

Although gestational diabetes is estimated to complicate between 1% and 5% of pregnancies, there are only limited data on the role of race/ethnicity as well as other risk factors in the development of this disorder. Epidemiologic characteristics of gestational diabetes were assessed in an ethnically diverse cohort of 10,187 women who had undergone standardized screening for glucose intolerance and who delivered a singleton infant at the Mount Sinai Medical Center in New York City between January 1987 and December 1989. The overall prevalence of gestational diabetes was 3.2%. Multiple logistic regression analysis showed excess risks for Oriental women, Hispanics born in Puerto Rico or elsewhere outside the United States, women from the Indian subcontinent and the Middle East, older mothers, heavier women, those with a positive family history of diabetes, women with a history of infertility, and those who delivered on the clinic service. These data suggest that, after controlling for traditional risk factors (maternal age, prepregnancy weight, and a family history of diabetes), Orientals, first generation Hispanics, women from the Indian subcontinent and the Middle East, those with a history of infertility, and low socioeconomic status women are at an increased risk for gestational diabetes.

Academic Medical Centers↗
PubMed1992

Relation of hostility to medication adherence, symptom complaints, and blood pressure reduction in a clinical field trial of antihypertensive medication.

The impact of hostility was examined in relation to the conduct and results of a clinical field trial. Data were derived from a multi-center randomized double-blind study of the comparative effects of antihypertensive therapy (captopril, methyldopa and propranolol) on the quality of life of 620 hypertensive men. Hostility levels were higher in subjects reporting skipping medication dosages compared to those reporting they always complied with the medication schedule. Reporting of symptoms often associated with antihypertensive drug regimens was positively related to hostility scores throughout the study, even during the blinded placebo period. Persons with high hostility scores showed the greatest decline in blood pressure independent of type of antihypertensive medication. However, there was some limited evidence that hostility levels were significantly reduced by one antihypertensive medication. Overall, the present findings suggest that double-blind pharmacologic clinical trials may benefit from using reliable measures of hostility as covariates in the evaluation of symptom reports and amount of blood pressure reduction.

Adult↗
PubMed1992

Inhibition of intimal hyperplasia by photodynamic therapy using photofrin.

Photodynamic therapy using photofrin and light energy inhibits human myofibroblast proliferation in cell culture. The purpose of this study is to evaluate its influence on intimal hyperplasia in vivo. Twenty New Zealand White rabbits underwent a standardized intimal injury to both common carotid arteries with a 2 Fr balloon catheter. One week later, half of the animals received photofrin (5 mg/kg) intravenously. The remaining 10 rabbits received no photofrin. Two days later, all neck incisions were reopened and a 1-cm segment of each of the 40 carotid arteries was exposed for 5 min to 80 mW of 630 nm light energy from a continuous wave tunable dye laser (fluence = 7.6 J/cm2). All vessels were harvested 5 weeks post-laser treatment following in vivo fixation with formalin. From each artery, separate cross-sections taken from both the lasered and non-lasered regions of each vessel were mounted and stained for histologic evaluation. Analyzed segments were then divided into four different treatment groups: group I segments consisted of arterial cross-sections which were taken from vessel regions that were injured but received neither photofrin nor laser treatment (group I, n = 20); group II segments also did not receive photofrin but were exposed to light energy (group II, n = 20); group III segments received photofrin but no light energy (group III, n = 20); and cross-sections in group IV were taken from those segments which received both photofrin and laser treatment. Using planimetry, the ratio of the area of intimal hyperplasia (IH) to the area enclosed by the internal elastic lamina (IEL) was measured for each specimen (IH/IEL).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Percutaneous absorption enhancement of leuprolide.

Chemical enhancers and vehicles were tested for their ability to improve the percutaneous absorption of leuprolide, a nonapeptide (luteinizing hormone releasing hormone analogue; MW 1209.4). In vitro permeabilities in nude mouse, snake, and cadaver skin were evaluated in either Franz diffusion cells or a Bronaugh flow-through system using an HPLC assay. Skin irritation caused by the formulations was evaluated in the rabbit. The chemical enhancer systems investigated strongly enhanced skin penetration of leuprolide. Maximum permeability enhancement of leuprolide acetate can be achieved with a nonirritating formulation containing ethanol, menthol, camphor, methyl salicylate, urea, and hydrogel. The in vitro permeability in nude mouse skin was 10 or 100 times higher than that obtained in cadaver skin, depending on the type of enhancer that was used in the formulation. Snake skin was at least 10 times less permeable than cadaver skin in this study. However, the effects of chemical enhancers on skin permeability were highly dependent on the skin model. Further, the in vitro permeability of leuprolide in the base form was 10 times higher than in the acetate form with the enhancers.

Acetates↗
PubMed1992

Linkage maps in pea.

We have analyzed segregation patterns of markers among the late generation progeny of several crosses of pea. From the patterns of association of these markers we have deduced linkage orders. Salient features of these linkages are discussed, as is the relationship between the data presented here and previously published genetic and cytogenetic data.

Chromosome Mapping↗
PubMed1992

Acuity-sensitivity trade-offs of X and Y cells in the cat lateral geniculate complex: role of the medial interlaminar nucleus in scotopic vision.

1. The cat medial interlaminar nucleus (MIN) receives inputs almost exclusively from tapetal retina, suggesting that the MIN has a special role in dim-light vision. In this study we compared the sensitivities of cells in the MIN with those in layers A and magnocellular C of the lateral geniculate nucleus (LGNd), using drifting sinusoidal gratings to determine contrast thresholds as a function of spatial frequency and retinal adaptation level over the entire scotopic range. 2. About one-half of the cells recorded in the MIN and layer A had brisk responses that could be nulled by properly positioned, counterphased sinusoidal gratings, and were classified as X cells. The rest of the cells in the MIN and layer A, as well as all cells recorded in layer C, were Y cells. 3. MIN cells had higher contrast sensitivity than layer A cells for low spatial frequencies (0.15 cycles/deg and below) over a wide range of adaptation levels, both overall and for separate comparisons within X or Y cells. Layer C Y cells were intermediate in sensitivity between MIN and layer A Y cells. For low spatial frequencies, Y cells as a group were more sensitive than X cells, whereas the reverse was true for high spatial frequencies. 4. These data enable one to determine the lowest adaptation level at which stimuli of a given contrast can be detected for a given structure. At the lowest spatial frequencies, the MIN can function at adaptation levels approximately 1 log unit below layer A, averaged over all stimulus contrasts. In contrast, the tapetum lowers luminance threshold by at most 0.16 log unit. 5. For scotopic conditions and eccentricities within 15 degrees of the area centralis, contrast sensitivity decreases with eccentricity for low spatial frequencies and remains flat or slightly increases for high spatial frequencies. This relationship, which is opposite to that found for photopic vision, is strongest for MIN Y cells. 6. These data support the hypothesis that the retinal conflict between sensitivity and acuity is ameliorated in the CNS through separate thalamic relays with different degrees of afferent convergence. MIN cells have higher luminance sensitivity than layer A cells, but at the expense of acuity. Layer C appears to occupy an intermediate position in this trade-off.

Animals↗
PubMed1992

Human airway macrophages. A technique for their retrieval and a descriptive comparison with alveolar macrophages.

We developed a technique to isolate and lavage a segment of a large human airway in vivo. Airway lavage and BAL were performed without significant complications 18 times on 17 normal volunteers. The mean +/- SEM volume of instillate used on all subjects totaled 31.3 +/- 2.7 ml with 47.1 +/- 3.8% of the fluid recovered. A total of 1.5 +/- 0.3 x 10(6) cells were retrieved. Cell viability averaged 71.3 +/- 4.6%. The majority of the cells were macrophages, 27.9 +/- 2.7%, and neutrophils, 28.4 +/- 6.0%. A descriptive comparison of airway macrophages using transmission electron microscopy with those retrieved from paired bronchoalveolar lavage (BAL) samples revealed that airway macrophages possessed more vacuoles (p less than 0.0001), fewer long microvilli (p less than 0.0001), and more membrane undulations (p less than 0.0001). In contrast, macrophages from both lavage locations demonstrated similar staining characteristics when stained with a panel of monoclonal antibodies. During lavage, all subjects experienced mild dyspnea that was relieved when the lavage was completed. One of three subjects tested during the procedure revealed O2 desaturation that was prevented by the inhalation of O2. We conclude that viable macrophages can be retrieved safely from airways of normal subjects and that, compared with macrophages present in BAL, these cells bear both similarities and dissimilarities that may portend differing functional capabilities.

Adult↗