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Biomedical subjects

G Lee

Publications and source records attributed to G Lee.

At least 253 records · Page 14Linked to original sources
PubMed1992

Interleukin-7 induces N-myc and c-myc expression in normal precursor B lymphocytes.

Expression of both N-myc and c-myc is induced rapidly and dramatically in normal pre-B cells after stimulation with interleukin-7 (IL-7), a pre-B cell-specific growth factor. These IL-7-induced increases in N-myc and c-myc expression are mediated at the transcriptional level; for N-myc, a major portion of the induction results from release of an attenuation block between exons 1 and 2. Although c-myc expression has been shown to be regulated by many factors, these studies provide the first demonstration of N-myc regulation by a growth factor. Furthermore, mitogen-induced proliferation of more mature B-lineage cells is accompanied by induction of c-myc expression in the complete absence of N-myc expression. Thus, N-myc expression in normal B-lineage cells, as in transformed cells, is limited to cells that represent the precursor stages of this differentiation pathway. Together, these findings imply a specific function for N-myc in the early stages of B-cell development.

Animals↗
PubMed1992

Serological identification of HLA-B13 subtypes.

A serological approach is used to confirm subtypes of HLA-B13 originally observed by one-dimensional isoelectric focusing (1D-IEF). Sixty anti-B13 alloantibody sera were screened against Chinese panel cells. Two clusters of sera showing distinct reactive patterns were identified. One is a shorter reactive pattern than the other. Using these serological reaction patterns, the B13 antigen can be divided into two subtypes, B13.1 and B13.2, in the Chinese population. These serological subtypes appear to correlate well with the 1D-IEF patterns of B13 subtypes. The serological subtyping is also in agreement with the differences in nucleotide sequence previously determined to exist in B13 antigen subtypes. Family studies show that both B13.1 and B13.2 segregate as HLA-B locus alleles. Gene frequencies for B13.1 and B13.2 were 0.0676 and 0.0612, respectively, in our study population of 337 southern Han Chinese.

Alleles↗
PubMed1992

Successful delivery of twins in a woman with a unicornuate uterus.

The presence of a unicornuate uterus is a rare congenital condition which represents only 1-2% of uterovaginal anomalies. Previous reports have demonstrated an increase in the number of cases of primary infertility, pregnancy loss and preterm labor associated with the unicornuate uterus. Herein, we present a case in which a patient conceived following a thawed frozen embryo transfer. She had been given the option of selective reduction, because of the high risk associated with this pregnancy, but refused and her pregnancy successfully continued to 35 weeks and delivery of twins.

Adult↗
PubMed1992

Expression of tau protein in non-neuronal cells: microtubule binding and stabilization.

The microtubule-associated protein tau is a developmentally regulated family of neuronal phosphoproteins that promotes the assembly and stabilization of microtubules. The carboxy-terminal half of the protein contains three copies of an imperfectly repeated sequence; this region has been found to bind microtubules in vitro. In addition, a fourth copy of the repeat has been found in adult-specific forms of tau protein. To examine the structure and function of tau protein in vivo, we have transiently expressed fetal and adult forms of tau protein and tau protein fragments in tissue culture cells. Biochemical analysis reveals full-length products with heterogeneity in post-translational modification synthesized in the cells. Immunofluorescent staining of transfected cells shows that, under our conditions, sequences on both sides of the repeat region are required for in vivo microtubule co-localization. These additional regions may be required either for enhancing microtubule contacts or for proper protein folding in the cell. In our expression system, the bundling of cellular microtubules occurs only in transfections using four-repeat tau constructs; any four-repeat construct capable of binding is also able to induce bundling. Our data suggest that the presence of bundles is correlated with enhanced microtubule stability; factors that increase stability such as higher levels of tau protein expression or the presence of the fourth repeat, increase the fraction of transfected cells showing bundles. Finally, the presence of tau protein in the cell allows all interphase microtubules to become acetylated, a post-translational modification usually reserved for a subset of stable cellular microtubules.

3T3 Cells↗
PubMed1992

The role of office hysteroscopy in in vitro fertilization.

Twenty-eight patients participated prospectively in a study to evaluate the impact of hysteroscopically detected uterine and cervical anomalies on the success rate of ET in an IVF-ET program. All participants had a normal intrauterine cavity by standard HSG. All the patients had a diagnostic office hysteroscopy under paracervical block before commencing COH. Because our IVF program does not include hysteroscopy as a requirement before undergoing IVF and because the significance of mild intrauterine abnormalities is not yet known, the hysteroscopic findings were not relayed to the personnel involved in the IVF-ET procedure. Sixteen patients (group I) had a normal hysteroscopic evaluation. Twelve patients (group II) had abnormal hysteroscopic findings including small uterine septa, small submucous fibroids, uterine hypoplasia and cervical ridges. Although no difference in patients or cycle characteristics was present, there was a significant difference in the clinical PR between patients in groups I and II. In conclusion, in an IVF-ET program patients with normal hysterography but abnormal hysteroscopic findings had a significantly lower clinical PR, demonstrating the importance of performing hysteroscopy before IVF-ET.

Adult↗
PubMed1991

Lee et al. reply.

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Journal Article↗
PubMed1991

Interactions between oxytocin, glucagon and glucose in normal and streptozotocin-induced diabetic rats.

Oxytocin has been suggested to have glucoregulatory functions in rats, man and other mammals. The hyperglycemic actions of oxytocin are believed to be mediated indirectly through changes in pancreatic function. The present study examined the interaction between glucose and oxytocin in normal and streptozotocin (STZ)-induced diabetic rats, under basal conditions and after injections of oxytocin. Plasma glucose and endogenous oxytocin levels were significantly correlated in cannulated lactating rats (r = 0.44, P less than 0.01). To test the hypothesis that oxytocin was acting to elevate plasma glucose, adult male rats were injected with 10 micrograms/kg oxytocin and killed 60 min later. Oxytocin increased plasma glucose from 6.1 +/- 0.1 to 6.8 +/- 0.2 mM (P less than 0.05), and glucagon from 179 +/- 12 to 259 +/- 32 pg/ml (P less than 0.01, n = 18). There was no significant effect of oxytocin on plasma insulin, although the levels were increased by 30%. A lower dose (1 microgram/kg) of oxytocin had no significant effect on plasma glucose or glucagon. To eliminate putative local inhibitory effects of insulin on glucagon secretion, male rats were made diabetic by i.p. injection of 100 mg/kg STZ, which increased glucose to greater than 18 mM and glucagon to 249 +/- 25 pg/ml (P less than 0.05). In these rats, 10 micrograms/kg oxytocin failed to further increase plasma glucose, but caused a much greater increase in glucagon (to 828 +/- 248 pg/ml) and also increased plasma ACTH. A specific oxytocin analog, Thr4,Gly7-oxytocin, mimicked the effect of oxytocin on glucagon secretion in diabetic rats. The lower dose of oxytocin also increased glucagon levels (to 1300 +/- 250 pg/ml), but the effect was not significant. A 3 h i.v. infusion of 1 nmol/kg per h oxytocin in conscious male rats significantly increased glucagon levels by 30 min in normal and STZ-rats; levels returned to baseline by 30 min after stopping the infusion. Plasma glucose increased in the normal, but not STZ-rats. The relative magnitude of the increase in glucagon was identical for normal and diabetic rats, but the absolute levels of glucagon during the infusion were twice as high in the diabetics. To test whether hypoglycemia could elevate plasma levels of oxytocin, male rats were injected i.p. with insulin and killed from 15-180 min later. Plasma glucose levels dropped to less than 2.5 mM by 15 min. Oxytocin levels increased by 150-200% at 30 min; however, the effect was not statistically significant.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of Variance↗
PubMed1991

Yield from total skin examination and effectiveness of skin cancer awareness program. Findings in 874 new dermatology patients.

The authors reviewed 874 dermatology charts to assess the acceptance rate of total skin examination (TSE), incidental skin findings, and patient compliance regarding treatment recommendations. Of the 874 new dermatology patients studied, 707 (80.9%) agreed to TSE. Important incidental findings were found in 151 (21.4%). These included: (1) biopsy specimen-confirmed malignant tumors (malignant melanoma, lentigo maligna, and basal cell and squamous cell carcinoma) in 24 of the 707 patients (3.4%), (2) biopsy specimen-confirmed premalignant tumors (actinic keratosis with dysplasia, Bowenoid actinic keratosis, Bowenoid papulosis, and lentigo with dysplasia, in five (0.7%), (3) clinically diagnosed premalignant actinic keratosis in 64 (9.1%), (4) biopsy specimen-confirmed dysplastic nevi in 17 (2.4%), and (5) congenital nevi in 41 (5.8%). Only 4.2% of the patients returned for a yearly TSE, and only 6.0% were found to follow all recommendations for monthly self examination, yearly professional examination, and sun protection. It is concluded that TSE for all new patients, and on a yearly basis for all return patients, is valuable in the detection of many skin conditions and allows skin cancer screening to be done, since patients for the most part do not follow recommendations for at-home screening.

Adult↗
PubMed1991

AGN 190383, a novel phospholipase inhibitor with topical anti-inflammatory activity.

AGN 190383 is a 5-hydroxy-2(5H)-furanone ring analog of the marine natural product manoalide. When applied topically, AGN 190383 inhibits phorbol ester induced mouse ear edema. It is a potent inhibitor of bee venom phospholipase A2 and blocks the release of arachidonic acid from calcium ionophore A23187 stimulated human neutrophils. AGN 190383 also inhibits both hormone-operated and depolarization-dependent calcium mobilization in GH3 cells, as well as fMLP stimulated increases in free cytosolic calcium in human PMNs. Furthermore, it is also able to block the release of the neutral protease elastase from stimulated neutrophils. The effects of AGN 190383 on arachidonic acid metabolism and leukocyte function may account, in part, for its anti-inflammatory activity in vivo.

Administration, Topical↗
PubMed1991

Overexpression of tau in a nonneuronal cell induces long cellular processes.

The ways in which the various microtubule-associated proteins (MAPs) contribute to cellular function are unknown beyond the ability of these proteins to modify microtubule dynamics. One member of the MAP family, tau protein, is restricted in its distribution to the axonal compartment of neurons, and has therefore prompted studies that attempt to relate tau function to the generation or maintenance of this structure. Sf9 cells from a moth ovary, when infected with a baculovirus containing a tau cDNA insert, elaborate very long processes. This single gene product expressed in a foreign host cell grossly alters the normal rounded morphology of these cells. The slender, relatively nonbranched appearance of these processes as well as their uniform caliber resembles the light-microscopic appearance of axons observed in several neuronal culture systems. Immunolabeling of the tau-expressing Sf9 cells demonstrated tau reactivity in the induced processes, and EM that microtubule bundles were present in the processes. Microtubule stabilization alone was insufficient to generate processes, since taxol treatment did not alter the overall cell shape, despite the induction of microtubule bundling within the cell body.

Alkaloids↗
PubMed1991

Epigenetic control of tumor cell morphology.

XC cell line derived from a single rat cell transformed by the Prague strain of Rous sarcoma virus produced morphologically different colonies. Among them, two distinct cell types consisting of thick, fusiform cells (L-type), and of flat, polygonal cells (R-type) were apparent. By repeated subclonings, pure cultures, L1 and R1, respectively, were obtained. These clones underwent morphological conversion during prolonged culture; L-type colonies appeared in the R-type clone and vice versa. The kinetic curve suggested that the conversion was multi-stepped. When inoculated into nude mice, L-type cells produced much larger tumors at a higher frequency than R-type cells, and the tumors induced by these two clones were histologically different. The expression of v-src gene was higher in L-type than in R-type cells at both mRNA and protein levels.

Actins↗
PubMed1991

Drug-exposed infants at home: strategies and supports.

This longitudinal, descriptive study gathered information on drug-exposed infants at home and identified effective public health nurse interventions for them and their caregivers. These infants exhibit symptoms that may well interfere with their ability to give clear cues as part of the infant-caregiver interactive system. This may amplify or perpetuate the effects of the drugs and low birth weight. Fifteen infants with a positive toxicology screen were compared to controls at birth and followed for up to 12 months of age through home visits by a public health nurse practitioner. The drug-exposed infants were significantly smaller at birth, and their most common initial problems were the need for nonnutritive sucking, excessive extensor tone, infections, and irritability. The mean weight, length, and head circumference went from the 10th to the 25th percentile at birth to the 25th to 50th percentile at 12 months. The support system and organization of the home predicted the family's ability to sustain caregiving for these infants. Effective strategies to care for these infants included recognizing states and cues, swaddling, use of pacifier, waking to eat, and smaller feedings. The role of the public health nurse was crucial for conducting early assessment, implementing strategies, and facilitating a therapeutic relationship.

Birth Weight↗