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Biomedical subjects

M K Park

Publications and source records attributed to M K Park.

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

Prevalence of overweight in a triethnic pediatric population of San Antonio, Texas.

OBJECTIVES: To investigate the prevalence of overweight among different ethnic and gender groups of children and adolescents in the San Antonio, Texas, area and to compare the prevalence with that of the US national figures. DESIGN: Cross-sectional study SUBJECTS: A total of 7208 schoolchildren in kindergarten through 12th grade. There were 4215 Mexican American (MA) (58.5%), 2040 non-Hispanic white (NHW) (28.3%) and 953 African American (AA) (13.2%) subjects. MEASUREMENTS: Weight, height and skinfold thicknesses. RESULTS: The body mass index (BMI, kg/m2) values of MA boys were almost consistently and significantly (P<0.05) larger than NHW boys and showed a tendency to be larger than AA boys, beginning as early as age 6 and continuing through age 17. Although rarely significant, a similar trend in ethnic difference was also noted for girls, with the smallest BMI seen in NHW girls. The subscapular skinfold thickness (SST) for MA boys and girls was significantly (P<0.05) larger than that for NHW counterparts and showed a tendency to be larger than AA counterparts. No significant ethnic differences were present in the triceps skinfold thickness (TST) for girls, but MA boys' TST were occasionally larger (P<0.05) than other ethnic-gender groups. Girls' TST were frequently larger (P<0.05) than boys for each ethnic groups. Using the population data from the National Health and Nutrition Examination Survey (NHANES) I as reference, the prevalence of overweight (BMI> or =95th percentile) was greater in MA (15-28%) and AA (11-29%) boys and girls than in NHW (7-17%) counterparts. The combined prevalence of overweight and 'at risk of overweight' (BMI>85th percentile) was much larger in MA boys (40-50%), MA girls (34-52%), and AA girls (33-51%) than other subgroups. The onset of overweight is quite early, starting at 5-6 y of age, especially in girls. Compared to the data from national surveys, the prevalence of overweight found in this study is higher than reported nationally. We found a marked increase in the skinfold thickness, especially SST for boys, but the increase is less for girls. CONCLUSIONS: The prevalence of overweight is higher in MA boys and girls and AA girls than other ethnic-gender groups in the San Antonio, Texas, area. The prevalence of childhood overweight in the San Antonio area is higher than national figures. The findings of increasing prevalence and early onset of childhood overweight are concerning, because these are known risk factors for diabetes and diseases of many other organ systems. Measures to prevent, reduce or treat childhood obesity are urgently needed.

Adolescent↗
PubMed2001

Chromogenic assay measuring opsonophagocytic killing capacities of antipneumococcal antisera.

Assays measuring opsonophagocytic killing capacity of immune sera are good surrogate assays for assessing pneumococcal vaccine responses, but they are tedious to perform primarily because the enumeration of surviving bacteria requires the counting of individual bacterial colonies. To overcome this limitation, we have developed a simple and rapid chromogenic assay for estimating the number of surviving bacteria. In this method, the conventional opsonophagocytic killing assays were performed in microtiter wells with differentiated HL-60 cells as phagocytes. At the end of the assay the reaction mixture was cultured for an additional 4.5 h to increase the number of bacteria. After the short culture, XTT (3,3'-[1[(phenylamino)carbonyl]-3,4-tetrazolium]-bis[4-methoxy-6-nitro] benzene sulfonic acid hydrate) and coenzyme Q were added to the wells and the optical density at 450 nm was measured. Our study shows that changes in the optical density were proportional to the number of CFU of live bacteria in the wells. Also, the number of bacteria at the end of the 4.5-h culture was found to be proportional to the original number of bacteria in the wells. When the performance of the chromogenic assay was evaluated by measuring the opsonizing titers of Streptococcus pneumoniae serotypes 6B and 19F, the sensitivity and precision of the new method were similar to those of the conventional opsonization assay employing the colony counting method. Furthermore, the results of this chromogenic assay obtained with 33 human sera correlate well with those obtained with the conventional colony counting method (R > 0.90) for the two serotypes (6B and 19F). Thus, this simple chromogenic assay would be useful in rapidly measuring the capacities of antisera to opsonize pneumococci.

Antibodies, Bacterial↗
PubMed2001

Patterns of chemokine expression in models of Schistosoma mansoni inflammation and infection reveal relationships between type 1 and type 2 responses and chemokines in vivo.

To explore the roles of chemokines in type 1 and type 2 responses in vivo, we examined mRNA expression for a panel of up to 17 chemokines in experimental mouse models using Schistosoma mansoni. These studies revealed that Mig (monokine induced by gamma interferon), cytokine-responsive gene 2/10-kDa interferon-inducible protein, RANTES, lymphotactin, macrophage inflammatory protein 1beta (MIP-1beta), JE/monocyte chemoattractant protein 1, and MIP-2 are associated with type 1 egg-induced responses and that thymus-derived chemotactic agent 3 (TCA3), eotaxin, MIP-1alpha, and MIP-1gamma are associated with type 2 egg-induced responses. After cercarial infection, both type 1-associated and type 2-associated chemokines were elevated in the livers of infected mice presensitized with eggs and recombinant interleukin-12 (rIL-12), a regimen that diminishes pathology. Neutralization of IL-12 or gamma interferon during egg deposition reversed the effects of prior treatment with rIL-12, leading to a return to larger granulomas; persistently elevated expression of TCA3, eotaxin, and MIP-1alpha; and a marked reduction in the expression of type 1-associated chemokines despite the maintenance of a dominant type 1 cytokine response in the draining lymph nodes. Our findings suggest that there are patterns of coordinate chemokine expression characteristic of type 1 and type 2 responses in vivo; that the cells recruited by a given pattern of chemokines may differ, depending on the composition of peripheral populations; and that patterns of tissue expression of chemokines may determine the character of an inflammatory response independently of the dominant pattern of differentiation of antigen-specific T cells. Our data reveal new relationships between chemokines and polarized immune responses and suggest that end organ inflammation might be altered by chemokine blockade without necessitating reversal of the phenotype of the majority of differentiated T cells.

Animals↗
PubMed2001

Structure and biological activity of gonadotropin-releasing hormone isoforms isolated from rat and hamster brains.

Rat and hamster brain tissues were used to investigate the possible existence of a follicle stimulating hormone (FSH)-releasing factor with similar characteristics to the lamprey gonadotropin-releasing hormone III (lGnRH-III) form proposed in previous reports. The present studies involved isolation and purification of the molecule by high-performance liquid chromatography (HPLC), identification by radioimmunoassay, sequence analysis by automated Edman degradation, mass spectrometry and examination of biological activity. Hypothalamic extracts from both species contained an HPLC fraction that was immunoreactive to GnRH and coeluted with lGnRH-III and 9-hydroxyproline mGnRH ([Hyp(9)]GnRH). Determination of primary structure from purified total brain material demonstrated that the isolated molecule was [Hyp(9)]GnRH. This is the first report showing the presence of the posttranslationally modified form already known as [Hyp(9)]GnRH by primary sequence analysis. The biological activity of distinct GnRH peptides was also tested in vitro for gonadotropin release using rat pituitary primary cell cultures. The results showed that [Hyp(9)]GnRH stimulated both luteinizing hormone and FSH release, as already reported, whereas lGnRH-III had no action on the secretion of either gonadotropin.

Amino Acid Sequence↗
PubMed2001

Primary structure of a novel gonadotropin-releasing hormone in the brain of a teleost, Pejerrey.

The neuropeptide GnRH is the major regulator of reproduction in vertebrates acting as a first signal from the hypothalamus to pituitary gonadotropes. Three GnRH molecular variants were detected in the brain of a fish, pejerrey (Odontesthes bonariensis), using chromatographic and immunological methods. The present study shows that one form is identical to chicken GnRH-II (sequence analysis and mass spectrometry) and the second one is immunologically and chromatographically similar to salmon GnRH. The third form was proven to be a novel form of GnRH by isolating the peptide from the brain and determining its primary structure by chemical sequencing and mass spectrometry. The sequence of the novel pejerrey GnRH is pGlu-His-Trp-Ser-Phe-Gly-Leu-Ser-Pro-Gly-NH(2), which is different from the known forms of the vertebrate and protochordate GnRH family. The new form of GnRH is biologically active in releasing gonadotropin and GH from pituitary cells in an in vitro assay.

Amino Acids↗
PubMed2001

Effect of carbon source on the mycelial growth and exo-biopolymer production by submerged culture of Paecilomyces japonica.

A significant difference was observed in the production pattern of exo-biopolymer and broth rheology during submerged culture of Paecilomyces japonica when two efficient carbon sources (maltose and sucrose) were employed. The maximum concentration of biopolymers in maltose medium (30 g/l) was higher than that in sucrose medium (25 g/l), whereas maximum mycelial concentration displayed an inverse result (i.e., 25 g/l in sucrose medium and 20 g/l in maltose medium). The broth rheology and morphology of P. japonica were also markedly different between the two culture media.

Journal Article↗
PubMed2001

Altered gabaa receptor subunit and splice variant expression in rats treated with chronic intermittent ethanol.

BACKGROUND: Intermittent chronic administration of ethanol to rats has been shown previously to produce a hyperexcitable, kindling-like state, accompanied by reduced inhibitory synaptic transmission in the hippocampus and changes in gamma-aminobutyric acid type A (GABAA) receptors. Further information is needed on the detailed changes in GABAA receptors and their time course and persistence, as is comparison to changes after chronic, continuous ethanol. METHODS: GABAA receptors were analyzed in the rat brain after chronic intermittent ethanol (CIE) by using radioligand binding, photoaffinity labeling of polypeptides, and estimates of messenger RNA (mRNA) levels of receptor subunits by reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridization. RESULTS: CIE rats were confirmed to have increased GABAA receptor binding of the benzodiazepine partial inverse agonist and ethanol antidote ligand Ro15-4513, due to increased expression of the alpha6 subunit polypeptide in the cerebellum, shown by photoaffinity labeling. Estimates of mRNA levels by use of RT-PCR did not reveal any significant increase in alpha6 or in several other receptor subunits in several brain regions, but a decrease in the ratio of the long and short splice variants (L/S) of the gamma2 subunit was detected in the hippocampus, especially the CA1 region. CONCLUSIONS: Changes in GABAA receptors were found in rats given CIE. Increased alpha6 subunit in the cerebellum was demonstrated by using both the binding to diazepam-insensitive sites for [3H]Ro15-4513 and increased levels of the 57-kDa alpha6 polypeptide after photoaffinity labeling with this ligand. This increase appeared after 30 doses of ethanol and decayed to normal 1 week after ethanol was discontinued. The transient change in cerebellar alpha6 subunit-containing receptors, also reportedly seen after chronic continuous ethanol, is thus unlikely to account for the persistently hyperexcitable, kindled, seizure-susceptible state seen in CIE. However, the significant decrease in gamma2 subunit L/S splice variant ratio in the hippocampus implies changes in GABAA receptor function, possibly involving protein phosphorylation by protein kinase C. Altered receptor trafficking and turnover associated with synaptic plasticity may contribute to the observed reduced inhibition in the hippocampus and other signs of alcohol dependence produced by CIE.

Alcoholism↗
PubMed2001

Differential diagnosis of Salmonella gallinarum and S. pullorum using PCR-RELP.

Salmonellosis in poultry of Korea is a significant health problem, which causes substantial economic losses. The most common causative agents of chicken salmonellosis ar S. gallinarum and S. pullorum. Traditional methods used to detect Salmoenella spp. In chicken are tedious, time consuming and confer little guarantee of sensitivity and species specificity. Therefore, a rapid and sensitive method for the differentiation of Salmonella serogroup D was assessed. We first amplified the rfbS genes by PCR and characterized the amplified product by nucleotide sequence analysis. The homology of nucleotide sequence was 99.7% between S. gallinarum and S. pullorum rfbS genes. Further comparisons of the sequences of S. gallinarum, S. gallinarum fied strain, S. pullorum and S. typhi(GenBank Accession No.M29682) showed a homology of 98.3%. The predicted amino acid sequence homology was 97.1%, 97.1% and 97.5%, respectively. Based on this comparison of these nucleotide sequences, we found unique restriction enzyme sites within the rfbS genes of S. gallinarum and S. pullorum. Thus, the PCR products could be further digested with restriction enzymes TfiI and PleI for use in a restriction fragment length polymorphism (RELP) technique. This method can be applied in the differential diagnosis between S. gallinarum and S. pullorum.

Animals↗
PubMed2000

Immunization of humans with recombinant pneumococcal surface protein A (rPspA) elicits antibodies that passively protect mice from fatal infection with Streptococcus pneumoniae bearing heterologous PspA.

Pneumococcal surface protein A (PspA), a cross-reactive protein expressed by all pneumococci, is known to elicit an antibody in animals that can passively protect mice from infection with Streptococcus pneumoniae. A phase I trial with recombinant PspA showed the protein to be immunogenic in humans. Pre- and postimmune serum samples from this trial were examined, and human antibody to PspA could protect mice from pneumococcal infection. The serum samples of subjects immunized twice with 125 microg of PspA had >100 times as much antibody per milliliter as was required to consistently protect mice from fatal infection (1.3 microg/dose). At least 98% of PspAs fall into PspA sequence/serologic families 1 or 2. Human antibodies elicited by a family 1 PspA protected against infection with S. pneumoniae expressing either family 1 or 2 PspAs and with strains of all 3 capsular types tested: 3, 6A, and 6B. These studies suggest that PspA may have efficacy as a human vaccine.

Adult↗
PubMed2000

The endoplasmic reticulum as one continuous Ca(2+) pool: visualization of rapid Ca(2+) movements and equilibration.

We investigated whether the endoplasmic reticulum (ER) is a functionally connected Ca(2+) store or is composed of separate subunits by monitoring movements of Ca(2+) and small fluorescent probes in the ER lumen of pancreatic acinar cells, using confocal microscopy, local bleaching and uncaging. We observed rapid movements and equilibration of Ca(2+) and the probes. The bulk of the ER at the base was not connected to the granules in the apical part, but diffusion into small apical ER extensions occurred. The connectivity of the ER Ca(2+) store was robust, since even supramaximal acetylcholine (ACh) stimulation for 30 min did not result in functional fragmentation. ACh could elicit a uniform decrease in the ER Ca(2+) concentration throughout the cell, but repetitive cytosolic Ca(2+) spikes, induced by a low ACh concentration, hardly reduced the ER Ca(2+) level. We conclude that the ER is a functionally continuous unit, which enables efficient Ca(2+) liberation. Ca(2+) released from the apical ER terminals is quickly replenished from the bulk of the rough ER at the base.

Acetylcholine↗
PubMed2000

Hypotonic swelling increases L-type calcium current in smooth muscle cells of the human stomach.

The purpose of the present study was to characterize the Ca2+ channels in smooth muscle cells from human stomach and to examine the effects of osmotic swelling on the channel activity. Ca2+ channel current with either Ca2+ or Ba2+ as charge carrier was recorded from freshly isolated smooth muscle cells using the conventional whole-cell patch clamp technique. The degree of cell swelling as a result of hypotonic challenge was monitored using a video image analysis system. The changes in intracellular Ca2+ concentration ([Ca2+]i) were measured by microfluorimetry. The pharmacological and voltage activation profile suggests a typical dihydropyridine-sensitive L-type Ca2+ current. Cell swelling, induced by hypotonic challenge, enhanced the amplitude of currents through L-type Ca2+ channels without significant effects on steady-state voltage dependency. After treatment with the L-type Ca2+ channel agonist Bay K 8644 (0.1-2 microM), no further significant increase in calcium channel current or corresponding [Ca2+]i transients were provoked by the swelling. The above results demonstrated that the presence of L-type Ca2+ current in smooth muscle cells of the human stomach and the augmentation of the current are closely associated with the volume increase resulting from hypotonic swelling.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2000

Steaming of ginseng at high temperature enhances biological activity.

The present study was performed to evaluate the effect of steaming ginseng at a temperature over 100 degrees C on its chemical constituents and biological activities. Raw ginseng was steamed at 100, 110, and 120 degrees C for 2 h using an autoclave. The ginseng steamed at 120 degrees C was more potent in its ability to induce endothelium-dependent relaxation. Steaming the raw ginseng at 120 degrees C also remarkably increased the radical-scavenging activity. Ginsenosides F(4), Rg(3), and Rg(5), which were not present in raw ginseng, were produced after steaming. Ginsenosides Rg(3) and Rg(5) were the most abundant ginsenosides in the ginseng steamed at 120 degrees C, accounting for 39% and 19% of all ginsenosides, respectively.

Chromatography, High Pressure Liquid↗
PubMed2000

A latex bead-based flow cytometric immunoassay capable of simultaneous typing of multiple pneumococcal serotypes (Multibead assay).

A simple and rapid method of simultaneously determining 15 Streptococcus pneumoniae serotypes was developed. Fifteen latex beads of different sizes and different red fluorescence levels were coated with 1 of 15 serotypes (1, 3, 4, 5, 6A, 6B, 7F, 9N, 9V, 14, 18C, 19A, 19F, 22F, and 23F) of pneumococcal capsular polysaccharide (PS). The bead mixture was incubated with individual pneumococcal lysate, a pool of rabbit antisera capable of binding the 15 serotypes, and fluorescein (green fluorescence)-conjugated anti-rabbit antibody. Bead size, red fluorescence, and green fluorescence were measured in a single flow cytometer run. The green fluorescence of the beads was inhibited only when there was a serotypic match between PS on the bead and PS in the pneumococcal lysate. This method distinguished cross-reactive serotypes and correctly identified the serotypes in 100% of 86 pneumococcal isolates tested.

Animals↗
PubMed2000

Peptide mimic of phosphorylcholine, a dominant epitope found on Streptococcus pneumoniae.

Even in the age of antibiotics, Streptococcus pneumoniae causes significant morbidity, especially in the young, the elderly, and the immunocompromised. While a carbohydrate-based vaccine exists, it is poorly immunogenic in the at-risk populations. In mice, antibodies directed against phosphorylcholine (PC), an epitope present on the cell wall C polysaccharide of all pneumococcal serotypes, protect against infection. However, PC itself is a poor vaccine candidate. We report here peptide mimics of PC based on the anti-idiotypic interaction of T15 anti-PC antibodies. T15 antibodies, the dominant and protective idiotype induced in mice by PC immunization, self-associate via a 24-amino-acid region in the PC binding site (ASRNKANDYTTEYSASVKGRFIVS; peptide 1). Peptide 1 has been shown to bind in the PC binding site. We demonstrated that amino acid sequences derived from peptide 1 starting at amino acid 9, 11, or 13 inhibit PC binding. Therefore, we immunized mice with bovine serum albumin (BSA) conjugates of peptide 1 or either of two selected 12-mers. The 12-mer peptides were not immunogenic. Mice immunized with peptide 1-BSA developed an anti-PC response consisting mainly immunoglobulin G1 and expressed the T15 heavy chain. Nonetheless, neither BALB/c nor CBA/N mice were protected from lethal pneumococcal infections by immunization with peptide 1-BSA. Preliminary data suggest that peptide 1-BSA is not able to elicit the canonical T15 light chain, explaining the absence of protection. This idiotype-derived mimotope of PC is a useful tool for understanding immunologic cross-reactivity and learning to design T-cell-dependent vaccines for S. pneumoniae.

Amino Acid Sequence↗
PubMed2000

Muscarinic receptors controlling the carbachol-activated nonselective cationic current in guinea pig gastric smooth muscle cells.

Muscarinic receptor subtypes controlling the nonselective cationic current in response to carbachol (ICCh) were studied in circular smooth muscle cells of the guinea pig gastric antrum using putative muscarinic agonists and antagonists. Both oxotremorine-M (an M2-selective agonist) and CCh dose-dependently activated the cationic current with EC50 values of 0.21 +/- 0.01 microm and 0.97 +/- 0.06 microM, respectively. In contrast, pilocarpine and McN-A 343 (an M1-selective and a putative M4 agonist) were weak partial agonists. In response to 10/microM CCh, 4-DAMP, methoctramine and pirenzepine dose-dependently inhibited ICCh and had IC50 values of 1.91 +/- 0.2 nM, 0.46 +/- 0.07 microM and 8.33 +/- 0.4 microM, respectively. 4-DAMP, methoctramine and pirenzepine shifted the concentration-response curves of ICCh to the right without significantly reducing the maximal current. Values of the apparent dissociation constant pA2 obtained from Schild plot analysis were 9.24, 7.72 and 6.62 for 4-DAMP, methoctramine and pirenzepine, respectively. Also, pertussis toxin completely blocked ICCh generation. These results suggest that the M2-subtype plays a crucial role in the activation of the ICCh, and a block of the M3-subtype reduces the sensitivity of the M2-mediated response with no significant reduction of maximum response.

Animals↗
PubMed2000

Thrombopoietin and chemokine mRNA expression in patient post-chemotherapy and in vitro cytokine-treated marrow stromal cell layers.

CD34(+) cells and megakaryocyte progenitors were lower in marrow from patients after hematological recovery from the first cycle of 5-fluorouracil, leucovorin, adriamycin, cyclophosphamide (FLAC) chemotherapy plus PIXY321 (GM-CSF/interleukin 3; IL-3 hybrid) than in FLAC + GM-CSF or pre-FLAC marrows. Marrow stromal layers, an in vitro model of the marrow microenvironment, express a combination of stimulatory and inhibitory factors that modulate hematopoietic progenitor cell proliferation and differentiation. The TaqMan assay and quantitative reverse transcriptase-polymerase chain reaction were used to measure monocyte chemoattractant protein-1 (MCP-1), melanoma stimulatory growth activity, and monokine inducible by interferon-gamma (Mig) (inhibitory chemokines for primitive or megakaryocyte progenitors) mRNA levels in in vitro PIXY and GM-CSF-treated and patient post-FLAC marrow stromal layers. Chemokine mRNA was increased after in vitro GM-CSF and to a lesser extent after PIXY treatment. MCP-1 mRNA levels were fivefold higher in FLAC + PIXY than in FLAC + GM-CSF layers, and Mig mRNA was elevated in FLAC + GM-CSF layers. Thrombopoietin (TPO), insulin-like growth factor I (IGF-I), and IGF-II (stimulatory factors for primitive and megakaryocyte progenitors) mRNA were also measured. TPO mRNA levels were 30% lower in GM-CSF and PIXY-pretreated than in control layers with no decrease in IGF mRNA. TPO mRNA in stromal layers of patients who developed grade 3 thrombocytopenia (platelets < 20 x 10(9)/l) during the third cycle of FLAC was only 24% of levels in stromal layers of marrow from other post-FLAC patients. Results demonstrate that patient and in vitro treatment had modulatory effects on TPO and chemokine mRNA expression in marrow stromal layers.

Antineoplastic Combined Chemotherapy Protocols↗