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Biomedical subjects

M Song

Publications and source records attributed to M Song.

At least 37 records · Page 2Linked to original sources
PubMed2001

Design and synthesis of new inhibitors of HIV-1 protease dimerization with conformationally constrained templates.

To inhibit the HIV-1 protease dimerization necessary to exhibit enzymatic activity, we synthesized and evaluated a new beta-sheet peptide (compound 1), containing 4-(2-aminoethyl)-6-dibenzofuranpropionic acid as a conformationally restricted linker and a non-peptidic beta-strand mimetic, 2-[3-([2-[(9-fluorenylmethoxy)carbonyl]hydrazino]carbonyl)-4-methoxyanilino]-2-oxoacetic acid (Fmoc-Hao-OH, compound 2). Kinetic analysis showed that compound 1 inhibited the dimerization of HIV-1 protease by a dissociative mechanism with a K(id) value of 5.4 microM at 37 degrees C (pH 5.0). However, compound 2 showed a small shift in the slope of the lines in the Zhang-Poorman plot (K(id)=9.1 microM), suggesting that compound 2 inhibits the dimerization of HIV-1 PR not only through a dissociative mechanism but also through an active-site directed mechanism partly. This is the first study of a non-peptidic inhibitor of HIV-1 protease dimerization.

Dimerization↗
PubMed2001

Angiogenic role for glycodelin in tumorigenesis.

Angiogenesis plays an important role in neovascularization in tumors. Glycodelin, a hormone-responsive protein, has been detected in tumors of reproductive organs and is found in high levels in the plasma of subjects with gynecological malignancies. Glycodelin is also found in the endothelial cells of the umbilical cord and in the blood vessels of tumors. In this study, we tested whether glycodelin-rich amniotic fluid and a synthetic peptide derived from the sequence of glycodelin peptide (Gp) might promote angiogenic response by examining the migration and tube formation in human umbilical cord vein endothelial cells (HUVECs). Increased migration and tube formation of HUVECs were found in the presence of amniotic fluid and Gp, and this increase was blocked by antibody to Gp and by an anti-vascular endothelial growth factor (VEGF) antibody, suggesting that the angiogenic effects of glycodelin might be mediated by VEGF. The results also showed that Gp significantly increased the release of VEGF protein and mRNA expression in HUVECs, RL-95 (human endometrial carcinoma cells), OVCAR-3 (human ovarian adenocarcinoma cells), EM42 (human endometrial epithelial cells), THP-1 (human monocyte), and MCF-7 and MDA-MB-231 (human breast adenocarcinoma cells) cell lines. VEGF receptor Fit-1 mRNA expression in HUVECs was also increased in the presence of Gp. These findings, together with the suggestion from the literature that glycodelin may have immunosuppressive properties, suggest that glycodelin might play an important role in neovascularization during embryogenesis and tumor development.

Amino Acid Sequence↗
PubMed2001

Remodeling of Kv4.3 potassium channel gene expression under the control of sex hormones.

Kv4.3 channels are important molecular components of transient K(+) currents (Ito currents) in brain and heart. They are involved in setting the frequency of neuronal firing and heart pacing. Altered Kv4.3 channel expression has been demonstrated under pathological conditions like heart failure indicating their critical role in heart function. Thyroid hormone studies suggest that their expression in the heart may be hormonally regulated. To explore the possibility that sex hormones control Kv4.3 expression, we investigated whether its expression changes in the pregnant uterus. This organ represents a unique model to study Ito currents, because it possesses this type of K(+) current and undergoes dramatic changes in function and excitability during pregnancy. We cloned Kv4.3 channel from myometrium and found that its protein and transcript expression is greatly diminished during pregnancy. Experiments in ovariectomized rats demonstrate that estrogen is one mechanism responsible for the dramatic reduction in Kv4.3 expression and function prior to parturition. Furthermore, the reduction of plasma membrane Kv4.3 protein is accompanied by a perinuclear localization suggesting that cell trafficking is also controlled by sex hormones. Thus, estrogen remodels the expression of Kv4.3 in myometrium by directly diminishing its transcription and, indirectly, by altering Kv4.3 delivery to the plasma membrane.

Animals↗
PubMed2001

Molten-globule structure and membrane binding of the N-terminal protease-resistant domain (63-193) of the steroidogenic acute regulatory protein (StAR).

The first step in steroidogenesis is the movement of cholesterol from the outer to inner mitochondrial membrane; this movement is facilitated by the steroidogenic acute regulatory protein (StAR). StAR has molten-globule properties at low pH and a protease-resistant N-terminal domain at pH 4 and pH 8 comprising residues 63-193. To explore the mechanism of action of StAR we investigated the structural properties of the bacterially expressed N-terminal domain (63-193 StAR) using CD, limited proteolysis and NMR. Far- and near-UV CD showed that the amount of secondary structure was greater at acidic than at neutral pH, but there was little tertiary structure at any pH. Unlike 63-193 StAR liberated from N-62 StAR by proteolysis, biosynthetic 63-193 StAR was no longer resistant to trypsin or proteinase K at pH 7, or to pepsin at pH 4. Addition of trifluoroethanol and SDS increased secondary structure at pH 7, and dodecylphosphocholine and CHAPS increased secondary structure at pH 2, pH 4 and pH 7. However, none of these conditions induced tertiary structure, as monitored by near-UV CD or NMR. Liposomes of phosphatidylcholine, phosphatidylserine and their mixture increased secondary structure of 63-193 StAR at pH 7, as monitored by far-UV CD, and stable protein-liposome complexes were identified by gel-permeation chromatography. These results provide further evidence that the N-terminal domain of StAR is a molten globule, and provide evidence that this conformation facilitates the interaction of the N-terminal domain of StAR with membranes. We suggest that this interaction is the key to understanding the mechanism of StAR's action.

Gene Products, env↗
PubMed2001

Decreased expression of voltage- and Ca(2+)-activated K(+) channels in coronary smooth muscle during aging.

Aging is the main risk factor for coronary artery disease. One characteristic of aging coronary arteries is their enhanced contractile responses to endothelial vasoconstricting factors, which increase the risk of coronary vasospasm in older people. Because large-conductance voltage- and Ca(2+)-activated K(+) channels (MaxiK) are key regulators of vascular tone, we explored the possibility that this class of channels is diminished with increasing age. Using site-directed antibodies recognizing the pore-forming alpha subunit and electrophysiological methods, we demonstrate that the number of MaxiK channels is dramatically diminished in aged coronary arteries from old F344 rats. Channel density was reduced from 52+/-9 channels/pF (3 months old) to 18+/-5 channels/pF (25 to 30 months old), which represents a 65% reduction in the older population. Pixel intensity of Western blots was also diminished by approximately 50%. Moreover, the age-related decrease in the channel protein expression was also evident in humans, which showed approximately 80% reduction in 61- to 70-year-old subjects compared with 3- to 18-year-old youngsters and approximately 45% reduction compared with 19- to 56-year-old adults. In agreement with a reduction of MaxiK channel numbers in aging coronary arteries, old coronary arteries from F344 rats contract less effectively ( approximately 70% reduction) than young coronary arteries when exposed to the MaxiK channel blocker iberiotoxin. The contraction studies indicate that under physiological conditions, MaxiK channels are tonically active, serving as a hyperpolarizing force that opposes contraction. Thus, reduced expression of MaxiK channels in aged coronary arteries would lead to a decreased vasodilating capacity and increased risk of coronary spasm and myocardial ischemia in older people.

Adolescent↗
PubMed2001

Accuracy of intravascular ultrasound for diameter measurement of phantom arteries.

BACKGROUND: Uniplanar quantitative angiography (QA) is the standard method for measuring vessel diameter during surgical and endovascular procedures. Intravascular ultrasound (IVUS), a relatively new technology, is another means of obtaining this measurement. This study was designed to validate the accuracy of these two modalities by comparing each to direct caliper measurement, the gold standard, using phantom femoral artery segments (PAS). MATERIALS AND METHODS: PAS diameter was measured with a 12.5-MHz mechanically rotating IVUS catheter (Boston Scientific Corp.) and QA (OEC Corp.) was compared to the direct caliper measurement (Mitutoyo Corp.) at 60 different locations within PAS. At each location minimal lumen diameter and perpendicular lumen diameter were measured and their mean was calculated. The intraclass correlation coefficients (ICCC) between direct caliper measurement and IVUS and uniplanar and biplanar angiography were calculated. Fisher's Z transformation was used to compare the correlation coefficients. RESULTS: The ICCC for IVUS was 0.89. The ICCCs for uniplanar and biplanar angiography were 0.73 and 0.82, respectively. IVUS correlated more closely with direct caliper measurement than uniplanar and biplanar angiography (P = 0.00008, 0.02) Biplanar angiography correlated more closely with direct caliper measurement than uniplanar angiography (P = 0.04). CONCLUSIONS: IVUS more accurately measures lumen diameter than uniplanar or biplanar angiography. Diameter measurement with biplanar angiography is more accurate than uniplanar angiography.

Angiography↗
PubMed2001

Rapid and sensitive determination of radiocesium (Cs-135, Cs-137) in the presence of excess barium by electrothermal vaporization-inductively coupled plasma-mass spectrometry (ETV-ICP-MS) with potassium thiocyanate as modifier.

An electrothermal vaporization-inductively coupled plasma-mass spectrometric (ETV-ICP-MS) method based on selective volatilization of cesium with KSCN as modifier has been developed for determination of radiocesium, i.e. 135Cs and 137Cs, in the presence of isobaric barium. A 10,000 times excess of barium, which was volatilized at a temperature of 1,100 degrees C, resulted only in a 1% signal increase in the signal of mass 135 amu. The recommended concentration of KSCN is 0.3 mM, and pretreatment and volatilization temperatures are 400 degrees C and 1,100 degrees C, respectively. A ramp time of 1 s is recommeded for the volatilization step. The achieved limit of detection for 135Cs is 0.2 pg/mL (10 microBq/mL) and 4 fg (0.2 microBq) absolute for a sample volume of 20 microL. This means a limit of detection for 137Cs of 0.2 pg/mL (0.6 Bq/mL) and of 4 fg (0.01 Bq) absolute. Signal variations of 135Cs and 137Cs, respectively, in spiked samples with various matrices were investigated.

Journal Article↗
PubMed2001

Segregation of effector mechanisms in a tumour-specific CD8+ T-cell clone correlates with CD30 expression.

In this study we have analyzed CD30-antigen expression in three melanoma-directed cytotoxic T lymphocyte (CTL) clones with a T helper 0 (Th0)-like cytokine secretion profile (i.e. interleukin (IL)-4, IL-5, and interferon (IFN)-gamma). We show that all CTL clones expressed high levels of CD30 upon contact with the autologous tumour cells. One CTL clone, termed A2 with a monoclonal feature was selected for further analyses and found its CD30 expression dependent on the presence of IL-4. Functionally, a CD30-expressing A2 CTL was capable of producing higher amounts of IFN-gamma (up to 1.5-fold) and IL-4 (up to two-fold) than its CD30- counterpart. Furthermore, CD30-positive A2 CTL displayed an at least three-fold greater proliferative response to the tumour cell stimulation, contrasting with CD30- CTL. However, the antitumour cytotoxic activity of A2 CTL was not modulated by the CD30 expression. These results suggest that CD30 antigen can be inducible on a subset of tumour-directed CD8+ CTL, and that this subset of cells may have profound effector functions, such as cytokine secretion, proliferation, and cytotoxicity.

Cell Line, Transformed↗
PubMed2001

Increased myeloperoxidase and lipid peroxide-modified protein in gynecological malignancies.

Oxidative stress has been implicated in several diseases, including cancer. Oxidants induce oncogenes and their products associated with cell growth. Even though epidemiological studies implicate oxidants in promoting cancer, there is still a lack of in vivo evidence for the same. In this study, we measured the levels of myeloperoxidase (MPO), an enzyme associated with oxidation and autoantibodies to lipid peroxide-modified protein (LOOH-RSA), in the plasma of subjects with gynecological cancers. The gynecological cancer subjects (n = 201) had higher plasma MPO and LOOH-RSA levels compared with control subjects (n = 60). Immunohistochemical analysis of tissues revealed that immunostaining for MPO and LOOH-RSA was higher in cancer tissues compared with controls. The staining was specific to cell types and not ubiquitously present. Neutrophils, monocytes/macrophages, and natural killer cells have been proposed to play a role in cancer promotion and progression. This study proposes a role for oxidative stress and especially MPO in cancer.

Adolescent↗
PubMed2001

A case of subungual reactive eccrine syringofibroadenoma.

Eccrine syringofibroadenoma (ESFA) is a rare eccrine tumor. We report the case of a 70-year-old woman who had presented a pincer nail deformity on the toes for 55 years and a left painless subungual tumor for 2 years. Histologic examination revealed branching anastomosing strands of epithelial cells with ductal structures in a fibrovascular stroma. The luminal cells showed positive staining for carcinoembryonic antigen, as in acrosyringeal cells and cells of dermal ducts. To our knowledge, our case is the first with a subungual location. In the context of chronic trauma due to a pincer nail, it may be classified in the reactive subtype recently described.

Adenoma, Sweat Gland↗
PubMed2001

Expression of scavenger receptor class B1 in endometrium and endometriosis.

Endometriosis is characterized by the presence of endometrial glands and stroma within the peritoneum and other extrauterine sites. The presence of aromatase, a key enzyme in the biosynthesis of estradiol, has been demonstrated in eutopic endometrial samples of women with moderate to severe endometriosis, but not in those of disease-free women. Animal studies have shown that high density lipoprotein provides precursor cholesterol pool for steroidogenesis. Scavenger receptor class B1, a 82-kDa cell surface protein, is involved in the binding of high density lipoprotein to target cells and promotes cholesteryl ester uptake. In this study we detected the presence of scavenger receptor class B1 in eutopic and ectopic endometrium. There was more scavenger receptor class B1 protein associated with endometriosis compared with matched endometrium. Two bands (82 and 45 kDa) were detected in the endometrium and endometriosis samples. Glycanase treatment indicated that the 45-kDa protein might be a nonglycosylated form of scavenger receptor class B1. Immunostaining of fixed tissues detected scavenger receptor class B1 in glandular epithelium of both tissues. Scavenger receptor class B1 and aromatase mRNA were increased in endometriosis tissues. Scavenger receptor class B1 expression in the endometrium and endometriosis supports a role for this receptor in the uptake of high density lipoprotein cholesterol, possibly supporting in situ estrogen production, which is detrimental in the progression of endometriosis.

Adult↗
PubMed2001

Determination of gamma-hydroxybutyrate in water and human urine by solid phase microextraction-gas chromatography/quadrupole ion trap spectrometry.

A simple method of detection was developed for gamma-hydroxybutyrate (GHB). The method involves the derivatization of GHB using a hexyl-chloroformate procedure in aqueous media (such as water or urine), extraction of the derivatization product directly from the sample using solid-phase microextraction, and subsequent separation and detection with gas chromatography quadrupole ion trap mass spectrometry. The deuterated form of GHB (GHB-D6) is used as an internal standard for quantitation. The method was linear for GHB-spiked pure water samples from 2 to 150 microg/mL GHB with a detection limit of 0.2 microg/mL. Spiked urine samples showed linearity from 5 to 500 microg/mL GHB with a detection limit of 2 microg/mL. The SPME-GC/MS method is applied to actual case samples, and the results are compared to those values obtained using a conventional GC/MS method. Sensitivity and linearity are comparable to those seen using traditional methods of separation, yet the SPME method is superior due to the simplicity, speed of analysis, reduction in solvent waste, and ability to differentiate between GHB and gamma-butyrolactone (GBL).

Anesthetics, Intravenous↗
PubMed2001

[Surgery of substernal goiter].

OBJECTIVE: To study the surgical approaches and operative techniques for substernal goiter. METHOD: A retrospective study of 27 cases with substernal thyroid nodules was made in our hospital. RESULT: The operations on 27 patients with substernal nodules have been successfully carried out. Among them, 10 were goiters, 9 adenomas, 4 malignancy and 4 were thyroid cancer metastasizing to paratracheal or substernal nodes. Resection via cervical collar incision was adequate in 23 cases. Three thyroid cancers with paratracheal node metastasis were completely resected by sternotomy and only one thyroid cancer with paratracheal and substernal nodes metastasis was resected by combined thoracotomy and cervical collar incision. CONCLUSION: Resection via cervical collar incision for all retrosternal thyroid nodules were advised. The preliminary experience with this procedure suggests that it has some advantages in the management of substernal goiter, including: 1. ease of operation compared to both sternotomy and thoracotomy; 2. relatively low morbidity; 3. safe and reliable.

Adult↗
PubMed2000

Partial paternal uniparental disomy of chromosome 6 in an infant with neonatal diabetes, macroglossia, and craniofacial abnormalities.

Neonatal diabetes, which can be transient or permanent, is defined as hyperglycemia that presents within the first month of life and requires insulin therapy. Transient neonatal diabetes mellitus has been associated with abnormalities of the paternally inherited copy of chromosome 6, including duplications of a portion of the long arm of chromosome 6 and uniparental disomy, implicating overexpression of an imprinted gene in this disorder. To date, all patients with transient neonatal diabetes mellitus and uniparental disomy have had complete paternal isodisomy. We describe a patient with neonatal diabetes, macroglossia, and craniofacial abnormalities, with partial paternal uniparental disomy of chromosome 6 involving the distal portion of 6q, from 6q24-qter. This observation demonstrates that mitotic recombination of chromosome 6 can also give rise to uniparental disomy and neonatal diabetes, a situation similar to that observed in Beckwith-Wiedemann syndrome, another imprinted disorder. This finding has clinical implications, since somatic mosaicism for uniparental disomy of chromosome 6 should also be considered in patients with transient neonatal diabetes mellitus.

Aneuploidy↗
PubMed2000

Identification of a new HLA-A(*)0201-restricted T-cell epitope from the tyrosinase-related protein 2 (TRP2) melanoma antigen.

For the development of peptide-based immunotherapies, the identification of additional tumor antigens and T-cell epitopes is required. Because HLA-A(*)0201 is the most common allele in Caucasians, who represent the majority of patients with melanomas, 6 peptides carrying an HLA-A(*)0201 motif were synthesized from tyrosinase-related protein-2 (TRP2) melanoma antigen and tested for binding affinity to the HLA allele using processing-defective T2 cells. These peptides were then pulsed onto autologous dendritic cells and used to stimulate in vitro CD8(+)-enriched T cells isolated from peripheral blood of HLA-A(*)02(+) healthy donors or melanoma patients for the induction of specific cytotoxic T lymphocytes (CTLs). One peptide, TRP2(288-296) (SLDDYNHLV), the best HLA-A(*)0201 binder, elicited specific CTLs from 1 of 4 patients and 3 of 4 healthy donors. The induced CTLs from the patient and from 1 donor efficiently recognized HLA-A(*)02(+) TRP2(+) melanomas as well as COS-7 cells expressing HLA-A(*)0201 and TRP2 in an HLA class I-restricted manner, as assessed by cytokine production and direct cytolysis. The remaining 2 CTL lines derived from 2 donors displayed low T-cell receptor avidity, which could lyse melanoma cells in the presence of exogenous peptide. Since TRP2 is an antigen expressed in most melanomas, identification of the TRP2/HLA-A(*)0201 peptide SLDDYNHLV may facilitate the design of present peptide-based immunotherapies for the treatment of a large fraction of melanoma patients.

Amino Acid Motifs↗
PubMed2000

Structural organization of the human NBC1 gene: kNBC1 is transcribed from an alternative promoter in intron 3.

Several electrogenic sodium bicarbonate cotransporters have been cloned from different human organs. In the renal proximal tubule, the electrogenic sodium bicarbonate cotransporter kNBC1 (1035aa) mediates the majority of basolateral sodium bicarbonate absorption. In pancreatic ducts, the electrogenic sodium bicarbonate cotransporter pNBC1 (1079aa) mediates basolateral sodium bicarbonate influx. hNBC1 (hhNBC), cloned from human heart, is identical to pNBC1 at the amino acid level. We have demonstrated that kNBC1 and pNBC1 are highly homologous proteins that have different N-termini. In kNBC1, 41 amino acids replace the initial 85 amino acids of pNBC1. Whether these proteins are coded by one or more genes is unknown. In order to determine the genetic basis for these transcripts, we first characterized the genomic organization of the NBC1 gene (SLC4A4). NBC1 spans approximately 450 kilobases containing 26 exons that are flanked by typical splice donor and acceptor sequences at the intron-exon boundaries. Exon 1 is specific for the pNBC1 transcript. The first alternative exon of the hNBC1 transcript, containing the 5'-untranslated region, is derived from the last 43 nucleotides of intron 1 in the NBC1 gene coupled to exon 2. kNBC1 is transcribed from an alternative promoter in intron 3. In the first alternative exon of kNBC1, the last 313 nucleotides of intron 3 are coupled to exon 4, which is common to pNBC1 and hNBC1. The major transcription initiation site in kNBC1 is located 192 nucleotides upstream from the translation initiation codon. A minor start site is located 182 nucleotides upstream from the translation initiation codon. Structural analysis of the proximal kNBC1 promoter revealed an atypical TATA sequence (-33) and several potentially important transcription factor binding sites. Functional studies showed that the 5'-flanking region of the alternative kNBC1 promoter (-159 to+43) is sufficient for promoter activity. This work is the first demonstration that the three N-terminal transcripts of the human electrogenic sodium bicarbonate cotransporter NBC1 are encoded by the SLC4A4 gene. Furthermore, knowledge of the genomic organization and alternative promoter usage in the NBC1 gene provides a molecular basis for understanding disorders involving electrogenic sodium bicarbonate cotransporters and facilitates the elucidation of transcriptional control of NBC1 expression.

Amino Acid Sequence↗