Conformational and color polymorphism of 5-methyl-2-[(2-nitrophenyl) amino]-3-thiophenecarbonitrile.
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Color↗
Biomedical subjects
L Yu
Publications and source records attributed to L Yu.
Anti-peptide monoclonal antibody imaging of a common binding domain involved in muscle regulation.
Multiple-component regulatory protein systems function through a generalized mechanism where a single regulatory protein or ligand binds to a variety of receptors to modulate specific functions in a physiologically sensitive context. Muscle contraction is regulated by the interaction of actin with troponin I (TnI) or myosin in a Ca(2+)-sensitive manner. Actin utilizes a single binding domain (residues 1-28) to bind to residues 104-115 of TnI (Van Eyk JE, Sönnichsen FD, Sykes BD, Hodges RS, 1991, In: Rüegg JC, ed, Peptides as probes in muscle research, Heidelberg, Germany: Springer-Verlag, pp 15-31) and to myosin subfragment 1 (S1, an enzymatic fragment of myosin containing both the actin and ATP binding sites) (Van Eyk JE, Hodges RS, 1991, Biochemistry 30:11676-11682) in a Ca(2+)-sensitive manner. We have utilized an anti-TnI peptide (104-115) monoclonal antibody, Mab B4, that binds specifically to TnI, to image the common binding domain of actin and thus mimic the activity of actin including activation of the S1 ATPase activity and TnI-mediated regulation of the S1 ATPase. Mab B4 has also been utilized to identify a receptor binding domain on myosin (residues 633-644) that is recognized by actin. Interestingly, Mab B4 binds to the native protein receptors TnI and S1 with relative affinities of 100- and 25,000-fold higher than the binding affinity to the 12-residue peptide immunogen. Thus, anti-peptide monoclonal antibodies prepared against a receptor binding domain can mimic the ligand binding domain and be utilized as a powerful tool for the detailed analysis of complex multiple-component regulatory systems.
Actins↗
Sexual dimorphism in transmission of expression of islet autoantibodies to offspring.
To help elucidate the mode of inheritance of insulin-dependent diabetes mellitus (IDDM), we measured GAD (glutamic acid decarboxylase) autoantibodies (GAD65Ab), insulin autoantibodies (IAA), and cytoplasmic islet cell autoantibodies (ICA) in 292 sequentially screened non-diabetic offspring of patients with IDDM. The prevalence of these islet autoantibodies was higher in offspring of diabetic fathers than in offspring of diabetic mothers. The prevalences of GAD65Ab, IAA, and ICA in the offspring of diabetic fathers were 11.5%, 10.8%, and 8.1% vs 2.1%, 1.4%, and 2.8%, respectively in the offspring of diabetic mothers (p < 0.002, p < 0.001, and p = 0.06 NS). Amongst autoantibody-positive relatives the IAA and ICA levels were significantly higher in offspring of diabetic fathers than of diabetic mothers (p < 0.002 and p < 0.01, respectively). The frequencies of these autoantibodies were equal in male and female offspring. We conclude that IDDM mothers transmitted islet autoimmunity less frequently to their offspring than IDDM fathers. Given the markedly lower frequency of autoantibodies in offspring of mothers, larger sample sizes will be required to determine whether islet autoantibodies are influenced by age of IDDM onset of mothers, maternal age of pregnancy, and presence of diabetes in these mothers prior to conception.
Adolescent↗
Effect of androgens and their manipulation on cell growth and androgen receptor (AR) levels in AR-positive and -negative human hepatocellular carcinomas.
BACKGROUND/AIMS: Little is known about genuine roles of androgens and their receptor in hepatocellular carcinoma. METHODS: In the present study, two sublines derived from a human hepatocellular carcinoma cell line KYN-1 were used: KYN-1/SM10 with androgen receptor and KYN-1/SM2 without androgen receptor. RESULTS: The binding assay with 3H-R1881 identified the presence of both cytosolic and nucleosolic androgen receptors in KYN-1/SM10 but not in KYN-1/SM2. In serum-free medium, dihydrotestosterone was able to enhance the cell proliferation and 3H-thymidine incorporation in androgen receptor positive KYN-1/SM10 cells. Such effects of dihydrotestosterone were partially inhibited by an antiandrogen cyproterone acetate in a concentration-dependent manner. On the other hand, the growth of androgen receptor negative KYN-1/SM2 cells was not influenced by dihydrotestosterone and cyproterone acetate at all. When dihydrotestosterone was removed from the medium of KYN-1/SM10 cultures, the nucleosolic androgen receptor decreased to undetectable levels within 8 h and the cytosolic androgen receptor within 48 h. Addition of dihydrotestosterone (10 nM) to the cells that had been deprived of dihydrotestosterone for 24 h partially restored both cytosolic and nucleosolic androgen receptor within 12 h. CONCLUSION: The current results seem to indicate that the growth of androgen receptor positive human hepatocellular carcinoma may be enhanced with androgen through androgen receptors and that antiandrogen therapy with cyproterone acetate may be effective in the treatment of androgen receptor-positive hepatocellular carcinoma.
Carcinoma, Hepatocellular↗
New insights into calicheamicin-DNA interactions derived from a model nucleosome system.
Using the Xenopus borealis 5S RNA gene, we have identified several new features of the interaction of calicheamicin (CAL), an enediyne antitumor agent, with nucleosomal and naked DNA targets. CAL-mediated DNA damage was generally reduced by incorporation of the DNA into a nucleosome. However, in one instance, the frequency of DNA damage was enhanced in the nucleosome compared to naked DNA. This increase in CAL damage may result from bending-induced changes in the target site, while the association of histone proteins with DNA in the nucleosome may generally reduce the affinity of CAL for its targets by imposing dynamic constraints on the DNA, by altering target structure, or by steric hindrance. One implication of these observations is that new structural features created by incorporation of DNA into chromatin may produce 'hot spots' for CAL-mediated DNA damage not apparent in naked DNA studies. In a second set of experiments, the orientation of CAL at damage sites in naked 5S rDNA was determined. The results suggest that minor groove width per se is not a major determinant of CAL target selection. Our studies support the generality of an oligopurine recognition element, with the additional requirement that the purine tract is interrupted at the 3'-end by a pyrimidine(s). To account for these observations, we propose a model in which CAL recognizes the unique structural and dynamic features associated with the 3'-end of an oligopurine tract. Finally, we conclude that the dyad axis of pseudosymmetry of the 5S rRNA gene nucleosome cannot be determined with any degree of certainty. This places significant limitations on the interpretation of results from the study of drug-DNA interactions with reconstituted nucleosomes.
Aminoglycosides↗
Expression of the mu-opioid receptor in CHO cells: ability of mu-opioid ligands to promote alpha-azidoanilido[32P]GTP labeling of multiple G protein alpha subunits.
The identities of heterotrimeric G proteins that can interact with the mu-opioid receptor were investigated by alpha-azidoanilido[32P]GTP labeling of alpha subunits in the presence of opioid agonists in Chinese hamster ovary (CHO)-MORIVA3 cells, a CHO clone that stably expressed mu-opioid receptor cDNA (MOR-1). This clone expressed 1.01 x 10(6) mu-opioid receptors per cell and had higher binding affinity and potency to inhibit adenylyl cyclase for the mu-opioid-selective ligands [D-Ala2,N-MePhe4, Gly-ol]-enkephalin and [N-MePhe3,D-Pro4]-morphiceptin, relative to the delta-selective opioid agonist [D-Pen2,D-Pen5]-enkephalin or the kappa-selective opioid agonist U-50,488H. mu-Opioid ligands induced an increase in alpha-azidoanilido[32P]GTP photoaffinity labeling of four G alpha subunits in this clone, three of which were identified as Gi3 alpha, Gi2 alpha, and Go2 alpha. The same pattern of simultaneous interaction of the mu-opioid receptor with multiple G alpha subunits was also observed in two other clones, one expressing about three times more and the other 10-fold fewer receptors as those expressed in CHO-MORIVA3 cells. The opioid-induced increase of labeling of these G proteins was agonist specific, concentration dependent, and blocked by naloxone and by pretreatment of these cells with pertussis toxin. A greater agonist-induced increase of alpha-azidoanilido[32P]GTP incorporation into Gi2 alpha (160-280%) and Go2 alpha (110-220%) than for an unknown G alpha (G? alpha) (60%) or Gi3 alpha (40%) was produced by three different mu-opioid ligands tested. In addition, slight differences were also found between the ability of various mu-opioid agonists to produce half-maximal labeling (ED50) of any given G alpha subunit, with a rank order of Gi3 alpha > Go2 alpha > Gi2 alpha = G? alpha. In any case, these results suggest that the activated mu-opioid receptor couples to four distinct G protein alpha subunits simultaneously.
Affinity Labels↗
Inhibition of the tumor promoting action of 12-O-tetradecanoylphorbol-13-acetate by tubeimoside III isolated from Bolbostemma paniculatum.
As tubeimoside I isolated from Bolbostemma paniculatum (Maxim.) Franquet (Cucurbitaceae) has been shown to suppress tumor promoter effects, tubeimoside III from the same plant was tested in vitro and in vivo against the action of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Tubeimoside III, the natural analog of tubeimoside I, also had an anti-inflammatory effect on mouse ear edema induced by arachidonic acid and TPA and a potent anti-tumor promoting effect on two-stage carcinogenesis of mouse skin after topical application. However, the important difference in bioactivities between tubeimosides I and III is the non-activity of tubeimoside III as an inhibitor of tumor promotion if administered orally. Differences in metabolism connected with different routes of the compound may be one of a number of explanations of the important difference.
Animals↗
Complications related to retained breast implant capsules.
Citing evidence that breast implant-related capsules resolve uneventfully, surgeons have elected to leave the capsules in place when implants are removed because capsulectomy adds both morbidity and expense to the procedure. However, recent clinical and histopathologic evidence suggests that uneventful resolution is not always the case, and several potential problems may arise from retained capsules after removal of the implant. Retained implant capsules may result in a spiculated mass suspicious for carcinoma, dense calcifications that obscure neighboring breast tissue on subsequent imaging studies, and cystic masses due to persistent serous effusion, expansile hematoma, or encapsulated silicone filled cysts. Furthermore, retained capsules are a reservoir of implant-related foreign material in the case of silicone gel-filled implants and textured implants promoting tissue ingrowth. To avoid complications from retained capsules, total capsulectomy or postoperative surveillance should be offered to patients.
Aged↗
Molecular cloning and characterization of a cellular protein that interacts with the human immunodeficiency virus type 1 Tat transactivator and encodes a strong transcriptional activation domain.
The mechanism by which human immunodeficiency virus type 1 Tat transactivates the long terminal repeat promoter is not understood. It is generally believed that Tat has one or more transcription factors as its cellular target. One might expect a cellular target for Tat to possess several properties, including (i) the ability to bind to the Tat activation region, (ii) the possession of a transcriptional activation domain, and (iii) the ability to contact the cellular transcription machinery. Here we describe the cloning, expression, and characterization of a human protein, termed TAP (Tat-associated protein), which possesses some of these properties. TAP is highly conserved in eukaryotes and is expressed in a variety of human tissues. The major intracellular species of TAP is a highly acidic 209-amino-acid protein that likely is formed by removal of a highly basic 70-amino-acid N-terminal segment from a primary translation product. By deletion analysis, we have identified a TAP C-terminal region rich in acidic amino acids and leucine residues which acts as a strong transcriptional activator when bound through GAL4 sites upstream of the core long terminal repeat promoter, as well as flanking sequences that mask the activation function. Amino acid substitution of two leucine residues within the core activation region results in loss of the TAP activation function. Two lines of evidence suggest that Tat interacts with TAP in vivo. First, promoter-bound Tat can recruit a TAP/VP16 fusion protein to the promoter. Second, transiently expressed Tat is found associated with endogenous TAP, as demonstrated by coimmuno-precipitation analysis. As shown in an accompanying report, the TAP activation region binds the Tat core activation region and general transcription factor TFIIB (L. Yu, P.M. Loewenstein, Z. Zhang, and M. Green, J. Virol. 69:3017-3023, 1995). These combined results suggest the hypothesis that TAP may function as a coactivator that bridges Tat to the general transcription machinery of the cell via TFIIB.
3T3 Cells↗
In vitro interaction of the human immunodeficiency virus type 1 Tat transactivator and the general transcription factor TFIIB with the cellular protein TAP.
We have reported the molecular cloning, expression, and characterization of a human cellular protein, TAP, which possesses a strong transcriptional activation domain and binds the human immunodeficiency virus type 1 Tat transactivator in vitro and in vivo (L. Yu, Z. Zhang, P.M. Loewenstein, K. Desai, Q. Tang, D. Mao, J.S. Symington, and M. Green, J. Virol. 69:3007-3016, 1995). Here we show that TAP binds the general transcription factor TFIIB. Furthermore, we delineate the binding domains of TAP, Tat, and TFIIB, as well as measure the strengths and specificity of these protein-protein interactions. TAP binds strongly to Tat, with a Kd of (approximately 2 to 5) x 10(-7) M. The Tat activation region contains a 17-amino-acid conserved core domain which is the single contact site for TAP. Single-amino-acid substitutions within the Tat core domain inactivate transactivation in vivo and in vitro and greatly reduce binding of Tat to TAP in vitro. TAP binds strongly to TFIIB, with about the same Kd as for Tat. The interaction between TAP and TFIIB requires a sequence near the carboxy terminus of TFIIB which is also required for binding the strong acidic activator VP16. The contact sites for Tat and TFIIB map within the TAP C-terminal region, which contains the TAP activation domain. These combined results are consistent with the hypothesis that TAP is a cellular coactivator that bridges the Tat transactivator to the general transcription machinery via TFIIB.
ATPases Associated with Diverse Cellular Activitie↗
Late progression to diabetes and evidence for chronic beta-cell autoimmunity in identical twins of patients with type I diabetes.
Previous studies suggest that after 6 years of discordance, identical twin pairs rarely become concordant for type I diabetes. With up to 39 years of follow-up from the onset of diabetes in the index twin, we determined how many discordant twins have evidence of beta-cell autoimmunity and how many develop overt diabetes. We longitudinally followed 23 pairs of identical twins (or triplets) that were selected from a total group of 30 pairs because they were discordant for type I diabetes when first ascertained. Seven developed diabetes after 3, 3, 7, 8, 9, 31 and 36 years of discordance. By survival analysis, the concordance after 10 years from the onset of diabetes in the index twin was estimated as 23% (95% confidence interval, 5-40%), increasing to 38% (95% confidence interval, 8-69%) after 31 years. Among 16 twins remaining nondiabetic at last follow-up (8-39 years of discordance), 12 were assessed with serial intravenous glucose tolerance tests and a total of 407 measurements by radioassay of antibodies against three defined autoantigens (glutamic acid decarboxylase, insulin, and the recently cloned molecule ICA512). Two-thirds (8 of 12) had evidence of beta-cell autoimmunity (persistently positive autoantibody levels) and/or first-phase insulin release less than the 1st percentile of control subjects. In summary, identical twins may develop diabetes after a prolonged period of discordance and approximately two-thirds of long-term discordant twins have evidence of persistent beta-cell autoimmunity and/or beta-cell damage. The concordance for beta-cell autoimmunity, therefore, is much higher than for overt diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
ICA512 autoantibody radioassay.
As part of a general program of screening islet expression libraries we have identified a clone from a lambda gt11 human islet expression library that reacts with human diabetic sera and, upon sequencing, was determined to be the neuroendocrine islet autoantigen ICA512 (islet cell antigen 512). In the current communication, we describe the development of a radioassay for autoantibodies to ICA512 (ICA512AA) using in vitro transcribed and translated protein for production of labeled antigen. Our initial results indicate that this radioassay is significantly more sensitive than the enzyme-linked immunosorbant assay, which uses a COOH-terminal fragment of ICA512. The ICA512AA radioassay uses a 96-well format with membrane separation of antibody bound from free antigen and should be readily adaptable to automated large-scale screening. Only 7 microliters of serum is required for triplicate determinations. In order to determine the specificity and sensitivity of this assay and estimate its positive predictive value, we have studied 42 new-onset diabetic patients, 33 first-degree relatives of diabetic patients followed to diabetes, 694 islet cell antibody-negative (ICA-) relatives, and 205 normal control subjects. Thirty-eight percent of new-onset patients and 48% of relatives followed to diabetes express autoantibodies to ICA512 exceeding the 99th percentile of the normal control subjects. In contrast, only 1.4% of ICA- first-degree relatives were positive for ICA512 autoantibodies.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Chemotherapy rapidly alternating with twice-a-day accelerated radiation therapy in carcinomas involving the hypopharynx or esophagus: an update.
Laboratory studies have suggested that rapidly alternating chemotherapy and radiation therapy might act synergistically. We undertook this study to evaluate the toxicity and effectiveness of this approach in patients with carcinoma involving the hypopharynx or esophagus. Between 1987 and 1991, we treated 47 patients (23 with carcinoma involving the hypopharynx and 24 with carcinoma involving the esophagus) by three cycles of chemotherapy (during weeks 1, 4, and 7) rapidly alternating with twice-a-day radiation therapy (during weeks 2, 5, and 8). Chemotherapy consisted of cisplatin 100 mg/m2 and 5-fluorouracil 3-4 g/m2 given over 4 days. Radiation therapy consisted of 180-200 cGy twice each day to 2000 cGy/cycle, total 6000 cGy over 7 weeks. The histology was squamous cell carcinoma in 44 patients and adenocarcinoma in 3 patients with esophagus cancer. Median follow-up is 2 years (range 1-5 years). The observed survival rate for all 47 patients was 54% at 1 year and 38% at 2 years. Acute toxicity was considerable. Twelve patients (25%) died during therapy from toxicity, without tumor progression, leaving 35 patients (18 hypopharynx, 17 esophagus) evaluable for response. Among the hypopharyngeal patients, 83% had a complete response, 11% had a partial response, and 6% had no response. Among the esophageal patients, 94% had a complete response, and 6% had a partial response. Local control was better for the esophageal patients than the hypopharyngeal patients (98% vs. 52% at 2 years, p = 0.038). The incidence of distant metastases was 25% at 2 years and not significantly different between the two groups. A high rate of local control was achieved, particularly in esophageal cancer, by delivering chemotherapy and radiation therapy in a rapidly alternating fashion. This was achieved at a considerable cost in terms of toxicity, however. Although our response rates and local control compare favorably with those of other recently published studies of combined modality therapy in esophagus or head and neck cancer, much additional work is required to reduce the toxicity and, in hypopharyngeal cancer, to further improve the local control.
Adenocarcinoma↗
Induced alterations in calcium uptake rate in normoxic rate proximal tubules.
This study is well-oxygenated, freshly isolated rat proximal tubules (RPT), examined the effects of several drugs that alter the transmembrane K+ and Na+ gradients across cell membranes, including valinomycin (VAL), amphotericin B (AMPHO), and ouabain (OUAB). The effects of high extracellular potassium chloride (KCl) concentrations (45 mM) and low extracellular sodium concentration (100mM) were also studied. After 10 min of drug exposure Ca2+ uptake rate (nmol/mg/min) increased from 2.7 to 3.8 with VAL (p < .02), from 2.9 to 3.7 with AMPHO (p < .05), from 3.6 to 4.1 with OUAB (p < .05), and from 3.2 to 4.8 with 45 mM KCl (p < .001). Ca2+ uptake rate was sustained at these high levels at 20 min in all treated RPT except those exposed to OUAB. LDH release averaged less than 15% in control tubules and did not increase significantly except in RPT treated with VAL, where LDH release at 10 min was 48% and at 20 min was 57% (both p < .001). Of importance, only in VAL-treated RPT did ATP decrease to low levels (6.7 nmol/mg in control to 2.0 +/- 0.3 nmol/mg in VAL, p < .001). Treatment with verapamil reduced Ca2+ uptake rates at 10 min in VAL-treated RPT (from 3.8 to 3.1, p < .02, in AMPHO-treated RPT (from 3.8 to 3.1 p < .001), in OUAB-treated tubules (from 4.0 to 3.4, p < .01), and in KCl-treated RPT (from 3.7 to 3.2, p < .01). These results indicate that acute changes in the transmembrane ion gradient in RPT are accompanied by increased Ca2+ uptake rates. Ca2+ uptake rates are also increased during O2 deprivation in RPT, a situation in which the transmembrane ion gradient is likewise altered. The increased Ca2+ uptake rate observed in the present study and during hypoxia may have a common basis, that is, altered transmembrane ion gradients or some function thereof.
Adenosine Triphosphate↗
[The diagnosis and treatment of insulinoma: an analysis on 20 cases].
From 1967 to 1994, a total of 20 pathologically proved benign insulinoma cases were treated in our hospital. Tumors were solitary in 19 cases, and multiple in 1, with diameter ranging from 0.5 to 3.0 cm. Diagnosis was made by autopsy in one and by laparotomy in 19. All 18 cases except for the one dying of pancreatic fistula postoperatively during the same hospitalization were followed up for 1 to 18 years without recurrence. The authors recommended calcium infusion test as the standard method of diagnosis, analysed the false diagnosis in one patient, and discussed operative experience on tumors deeply buried in the head of the pancreas.
Follow-Up Studies↗
[Audiological test results of the autoimmune sensorineural hearing loss].
Audiological test results of 71 cases (130 ears) of clinically diagnosed autoimmune sensorineural hearing loss were analysed. Their audiograms can be divided into 4 types: low-frequency loss (55 ears), flat-type (26 ears), bell-type (17 ears) and high-frequency loss (32 ears). The test results of TEOAE, ABR, and -SP/AP amplitude ratio showed that the site of lesions in most of the low-frequency loss were retrocochlear, and most of the other three types were cochlear. Since about 1/3 of cases were chiefly involved retrocochlearly, the term "Autoimmune inner ear diseases" should not be used to substitute "Autoimmune sensorineural hearing loss".
Adolescent↗
[Experimental studies of glomerular endothelial cell culture and its production of extracellular matrixes].
We successfully cultured human fetal and bovine glomerular endothelial cells by cell cloning and maintained seven passages. The glomerular endothelial cells were identified by indirect immunofluorescence method. We found that the fetal and bovine glomerular endothelial cells could produce factor VIII related antigen, fibronectin, type IV collagen and laminin. The extracellular matrixes in the cultured supernatant were determined at various stages. The results showed that the glomerular endothelial cells could produce extracellular matrixes steadily without any stimulating factor.
Animals↗
[The clinical significance of detecting minimal residual disease in the bone marrow of patients with B-cell neoplasm].
Clonal IgH gene rearrangement as a gene marker of B-cell malignancies, a new method of polymerase chain reaction amplification in conjunction with single-strand conformational polymorphism (PCR-SSCP) analysis was performed on the stored bone marrow slide specimens from patients with B cell neoplasm for detecting minimal residual disease (MRD). The method was sensitive to 1-2 malignant B-cells in 1,000 normal bone marrow cells. In untreated patients with B-NHL, the incidence of MRD in bone marrow specimens was 68.4% (26/38). Patients with MRD in bone marrow had a shorter survival time than those without (P < 0.05). In patients with B-ALL in complete clinical remission, the incidence of MRD in bone marrow was 71.4% (15/21). There was a tendency of relapse in patients with MRD in bone marrow but persistent complete remission in patients without. The results showed that detection of MRD in bone marrow may provide some important information for assessing prognosis and predicting relapse in patients with B-cell malignancy.
Adolescent↗