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H Jung

Publications and source records attributed to H Jung.

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

Glucocorticoid inhibits growth factor-induced differentiation of hippocampal progenitor HiB5 cells.

In the present study, we investigated the effect of glucocorticoid on neuronal differentiation of hippocampal progenitor HiB5 cells. Dexamethasone (DEX), a synthetic glucocorticoid, inhibited platelet-derived growth factor (PDGF)-induced differentiation of HiB5 cells. The inhibitory effect of DEX was antagonized by RU486, a glucocorticoid receptor (GR) antagonist, indicating the GR-mediated processes. Nestin mRNA level was decreased and midsize neurofilament (NF-M) mRNA level was increased as a function of neuronal differentiation. DEX significantly blocked PDGF-induced down-regulation of nestin mRNA level, and up-regulation of NF-M mRNA level, which were similar to those of undifferentiated cells. DEX inhibited PDGF-induced activation of cyclic AMP-responsive element binding protein (CREB) and AP-1, suggesting that glucocorticoid interfered with signal transduction cascades linking the PDGF receptor and downstream transcription factors. Indeed, DEX reduced PDGF-induced phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2). Tyrosine phosphatase inhibitor reversed the effect of DEX on ERK1/2. In accordance with this finding, blockage of ERK1/2 signaling pathway with PD098059, a potent inhibitor for Ras/ERK pathway, mimicked the inhibitory effect of DEX on differentiation processes. Taken together, these results indicate that glucocorticoid inhibits PDGF-induced differentiation of hippocampal progenitor HiB5 cells by inhibiting the ERK1/2 signaling cascade via a tyrosine phosphatase-dependent mechanism.

Blotting, Southern↗
PubMed2001

Unilateral congenital oculomotor nerve palsy, optic nerve hypoplasia and pituitary malformation: a preliminary report.

A newborn male presented with complete external third nerve palsy of his right eye immediately at birth. Pediatric examination and MRI of the skull revealed no abnormalities. At the age of six weeks, strabismus surgery was performed to facilitate amblyopia treatment. The muscles appeared small and fibrotic. At the age of ten weeks, a brow suspension of the upper lid and a second strabismus surgery were performed. The amblyopia treatment and patching, applied for half of the waking hours over a period of six weeks, were unsuccessful. At the age of six months, a relative pallor of the right optic nerve head became evident. At the age of three years, at a new examination because of growth deficiency, a second MRI revealed defects involving the pituitary region. We concluded that extraocular muscle abnormality or oculomotor nerve palsy was present together with optic nerve dysplasia and pituitary gland malformation.

Amblyopia↗
PubMed2001

Cloning and expression analysis of Phytoplasma protein translocation genes.

Genes encoding SecA and SecY proteins, essential components of the Sec protein translocation system, were cloned from onion yellows phytoplasma, an unculturable plant pathogenic bacterium. The secA gene consists of 2,505 nucleotides encoding an 835 amino acid protein (95.7 kDa) and shows the highest similarity with SecA of Bacillus subtilis. Anti-SecA rabbit antibody was prepared from a purified partial SecA protein, with a histidine tag expressed in Escherichia coli. Western blot analysis confirmed that SecA protein (approximately 96 kDa) is produced in phytoplasma-infected plants. Immunohistochemical thin sections observed by optical microscopy showed that SecA is characteristically present in plant phloem tissues infected with phytoplasma. The secY gene consists of 1,239 nucleotides encoding a 413 amino acid protein (45.9 kDa) and shows the highest similarity with SecY of B. subtilis. These results suggest the presence of a functional Sec system in phytoplasmas. Because phytoplasmas are endocellular bacteria lacking cell walls, this system might secrete bacterial proteins directly into the host cytoplasm. This study is what we believe to be the first report of the sequence and expression analysis of phytoplasma genes encoding membrane proteins with a predicted function.

Acholeplasmataceae↗
PubMed2001

Consistency and efficiency of standard swipe procedures taken on slightly radioactive contaminated metal surfaces.

In radiation work areas, a standard "swipe" procedure is widely used to evaluate the extent of contamination on surfaces. This report documents the variability in results of swipes carried out on various metal surfaces and the variability between different experienced health physics technicians. Also, there is an issue of the efficiency of the first swipe in terms of what fraction of the total absorbed surface contamination is detected by a swipe. The samples used for this study were metal surfaces uniformly exposed in the spent fuel pool of a nuclear power plant The primary surfaces studied were those usually found on spent fuel transportation casks (mainly 304 stainless steel in the U.S.), which are submerged in the spent fuel pools for loading or unloading of the highly radioactive fuel assemblies from nuclear power plants. These surfaces become contaminated with suspended and dissolved radionuclides, primarily 137Cs, 134Cs, and 60Co, in the spent fuel pool. A detailed evaluation was conducted of variations in the swipe measurements made on these metal samples using repeated swipes of the same area by the same technician and comparing swipes of one technician to those of another on similar surfaces. Rough surface finishes showed considerable inconsistency (approximately 30% variation) from one technician to another, but smooth surface finishes show substantially better consistency (<10% variation) between technicians. The "efficiencies" of a single swipe, particularly the initial swipe, expressed as a fraction of total "removable" contamination, ranged from approximately 10% to 20% for the stainless steel and titanium surfaces. Aluminum surfaces, on the other hand, showed much higher efficiencies on the initial swipe. However, in terms of the total contamination imbedded in the surfaces, the first swipe picked up only between 0.5% and 3% of the total adsorbed contamination. The overall results show the wide variations that routinely occur in swipe results on portions of surfaces that would be expected to give consistent results. These difference are an order of magnitude or more greater than the counting statistical errors.

Adsorption↗
PubMed2000

Spin labeling analysis of structure and dynamics of the Na(+)/proline transporter of Escherichia coli.

With respect to the functional importance attributed to the N-terminal part of the Na(+)/proline transporter of Escherichia coli (PutP), we report here on the structural arrangement and functional dynamics of transmembrane domains (TMs) II and III and the adjoining loop regions. Information on membrane topography was obtained by analyzing the residual mobility of site-specifically-attached nitroxide spin label and by determination of collision frequencies of the nitroxide with oxygen and a polar metal ion complex using electron paramagnetic resonance (EPR) spectroscopy. The studies suggest that amino acids Phe45, Ser50, Ser54, Trp59, and Met62 are part of TM II while Gly39 and Arg40 are located at a membrane-water interface probably forming the cytoplasmic cap of the TM. Also Ala67 and Glu75 are at a membrane-water interface, suggesting a location close to the periplasmic ends of TMs II and III, respectively. Ser71 between these residues is clearly in a water-exposed loop (periplasmic loop 3). Spin labels attached to positions 80, 86, and 91 show EPR properties typical for a TM location (TM III). Leu97 may be part of a structured loop region while Ala107 is clearly located in a water-exposed loop (cytoplasmic loop 4). Finally, spin labels attached to the positions of Asp33 and Leu37 are clearly on the surface of the transporter and are directed into an apolar environment. These findings strongly support the recently proposed 13-helix model of PutP [Jung, H., Rübenhagen, R., Tebbe, S., Leifker, K., Tholema, N., Quick, M., and Schmid, R. (1998) J. Biol. Chem. 273, 26400-26407] and suggest that TMs II and III of the transporter are formed by amino acids Ser41 to Gly66 and Ser76 to Gly95, respectively. In addition to the topology analysis, it is shown that binding of Na(+) and/or proline to the transporter alters the mobility of the nitroxide group at the positions of Leu37 and Phe45. From these findings, it is concluded that binding of the ligands induces conformational alterations of PutP that involve at least parts of TM II and the preceding cytoplasmic loop.

Amino Acid Sequence↗
PubMed2000

Micellar electrokinetic chromatography for the analysis of D-amygdalin and its epimer in apricot kernel.

We have developed a simple, rapid and reproducible method for the determination of D-amygdalin and its epimer by using micellar electrokinetic chromatography (MEKC). Separation of D-amygdalin was performed in a 20 mM sodium borate buffer (pH 8.5) containing 300 mM sodium dodecyl sulfate using a bare fused-silica capillary. The eluates were monitored by the absorbance at 210 nm. The applied electric field was 278 V/cm, and the time needed for the separation of D-amygdalin did not exceed 6 min. The calibration curve for D-amygdalin showed excellent linearity in the concentration range of 5-500 microg/ml. The migration time and the corrected peak area show relative standard deviations (n=6) of 0.86% and 1.48%, respectively. The limit of detection (S/N=3) for D-amygdalin was 2 microg/ml. Under acidic and neutral conditions, amygdalin exists only as the D-form; however, under basic conditions, it shows both the D- and L-forms with a concentration ratio of 1:1.3 (D-amygdalin/L-amygdalin). Results of HPLC, UV-Vis spectrophotometry, and mass spectrometry reconfirmed the identification of D-amygdalin and its epimer. The number of theoretical plates of D-amygdalin is about 100,000 in MEKC, which is significantly higher than approximately 8,000 of HPLC. This method has been successfully applied to the determination of amygdalin epimers in various apricot kernel extracts and pharmaceutical products.

Amygdalin↗
PubMed2000

Osmosensor and osmoregulator properties of the betaine carrier BetP from Corynebacterium glutamicum in proteoliposomes.

The secondary glycine betaine uptake system BetP of Corynebacterium glutamicum was purified from Escherichia coli membranes in strep-tagged form after heterologous expression of the betP gene and was reconstituted in E. coli lipids. BetP retained its kinetic properties (V(max) and K(m) for betaine and Na(+)) as compared with intact cells. The influence of driving forces (Na(+) gradient and/or electrical potential) on betaine uptake was quantified in proteoliposomes. BetP was effectively regulated by the external osmolality and was stimulated by the local anesthetic tetracaine. A shift of the optimum of osmotic stimulation to higher osmolalities was linearly correlated with an increasing share of phosphatidyl glycerol, the major lipid of the C. glutamicum plasma membrane in the E. coli lipid proteoliposomes. This finding correlates with results demonstrating an identical shift when betP was expressed in E. coli instead of C. glutamicum. These data indicate that (i) BetP comprises all elements of osmosensing and osmoregulatory mechanisms of betaine uptake, (ii) osmoregulation of BetP is directly related to protein/membrane interactions, (iii) the turgor pressure presumably plays no major role in osmoregulation of BetP, and (iv) the regulatory properties of BetP may be related to the physical state of the surrounding membrane.

Bacterial Proteins↗
PubMed2000

Competitive binding of a Tris run buffer with chiral crown ether in chiral capillary electrophoresis.

In capillary electrophoresis of primary amine racemates using (+)-(18-crown-6)-tetracarboxylic acid (18C6H4) as a chiral selector, chiral recognition emanates from the differences in the complex formation between 18C6H4 and the two protonated amine enantiomers. The presence of buffer constituents such as tris(hydroxymethyl)aminomethane (Tris) or Na+, capable of forming complexes with 18C6H4, is thus detrimental to the chiral separation of primary amines. Such a competitive binding of buffer constituents was studied by comparing the electrophoretic mobilities of racemic analytes obtained in Tris/citric acid and triethylamine/citric acid buffers. We developed a simple fitting method to determine the competitive binding constant and applied it to the Tris buffer system. The competitive binding constant of Tris with 18C6H4 obtained at pH 3.0 was 27 +/- 4.

Anti-Infective Agents↗
PubMed2000

The effects of E2 supplementation from the early proliferative phase to the late secretory phase of the endometrium in hMG-stimulated IVF-ET.

PURPOSE: Our purpose was to determine if pregnancy rates (PRs) for hMG (human menopausal gonadotropin)-stimulated IVF-ET (in vitro fertilization--embryo transfer) can be increased by estradiol (E2) supplementation from the early proliferative phase to the late secretory phase of the endometrium. METHOD: Eighty-one infertile women with pure tubal factor were randomized into two groups. One group received no E2 supplementation (control group) and the other received oral E2 supplementation (2 mg two times daily) from the early proliferative phase starting on the third day of the menstrual cycle to the late secretory phase of the endometrium, with hMG stimulation for ovulation induction starting on the sixth day of the menstrual cycle. RESULTS: In 85 cycles, at least one embryo was transferred. Compared with the control group (n = 27 cycles), the E2 supplementation group (n = 58 cycles) had a significantly higher PR (control, 25.9%, versus E2 supplementation, 48.3%) and IR per ET (control, 10%, versus E2 supplementation, 26%), but FRs per retrieved oocytes were not statistically different between the two groups (control, 74%, versus E2 supplementation group, 73%). Four spontaneous abortions occurred in the E2 supplementation group, and one case in the control group. Ectopic pregnancy occurred in one case in the control group. CONCLUSIONS: Clinical PRs and IRs in the E2 supplementation group were significantly higher than in the control group, while FRs in the control group did not differ statistically from the E2 supplementation group. This suggests that E2 supplementation from the early proliferative phase to the late secretory phase of the endometrium in hMG-stimulated IVF-ET increases the receptivity of the endometrium for transferred embryos and clinical PRs.

Adult↗
PubMed2000

Potentiating effect of obacunone from Dictamnus dasycarpus on cytotoxicity of microtuble inhibitors, vincristine, vinblastine and taxol.

The limonoid triterpene, obacunone, was found to enhance the cytotoxicity of vincristine against L1210 cells by approximately 10-fold. Further, it was found that the cytotoxicity of other microtubule inhibitors such as vinblastine and taxol in drug-sensitive KB-3-1 cells as well as in multidrug-resistant KB-V1 cells was enhanced greatly in the presence of obacunone. On the other hand, there was no remarkable potentiating effect of obacunone on the cytotoxicity of other antineoplastic drugs such as adriamycin, cisplatin or 5-fluorouracil. From these results, it is implied that the potentiating action of obacunone may be limited to microtubule inhibitors.

Animals↗
PubMed2000

[Recurrent laryngeal nerve paralysis after thyroidectomy].

AIM: The paper's aim is to examine and analyse the incidence rate of postoperative pareses of N. recurrens in 1311 operated thyroid sides and 909 patients. PATIENTS AND SURGICAL TECHNIQUE: In histology we found nodular changes in 92.6% of 840 operated benignant strumata. In 69 malignant strumata the papillary thyroid carcinoma was the most common. The surgical concept changed within the last years from subtotal resections and enuclations to functional and total resections. RESULTS: Preoperative pareses of N. recurrens were seen in 5.3% of the patients, which emphasizes the demand for a preoperative laryngologic examination. Surgery on relapsed benignant strumata were followed by permanent unilateral pareses of N. recurrens in 9.9%, surgery on malignant strumata in 7.5% of the cases. After surgery of relapsed malignant strumata we found 2 permanent pareses in 21 reoperated thyroid sides. During a regular follow-up over the period of 12 months at least, we saw 22 transitory pareses of N. recurrens, which corresponds to a reversibility rate of 35%. In first surgical interventions with benignant histology the reversibility rate was 49%. Depending on first or relapse surgery, the histological findings and chosen surgical method the rate of permanent unilateral pareses of N. recurrens was only 1.7% in relation to the first time operated sides of benignant strumata.

Adenoma↗
PubMed2000

[The radiation risks from x-ray studies for age assessment in criminal proceedings].

AIM: Age estimation for forensic purposes is, in general, based on a radiogram of the left hand or an orthopantomogram of the teeth. Two examples are given exemplifying the principal procedure that may be applied for estimating the radiation risks associated with the radiological examinations considered. METHOD: Mortality risks were calculated using the risk coefficients of ICRP and the mass ratio of radiation-exposed portion to total organ. For a radiogram of the hand, a radiation dose of 0.15 mGy was adopted. For an orthopantomogram the following doses were used: bone surface and red bone marrow 0.25 mGy, skin on the neck 0.56 mGy, thyroid gland 0.053 mGy. RESULTS: Mortality risks obtained were 5.1 x 10(-8) for a radiogram of the hand and 1.8 x 10(-7) for an orthopantomogram. For comparison, it was estimated that the calculated risks might be equivalent to the mortality risks associated with public road traffic during less than one hour or about 2.5 hours, respectively. CONCLUSIONS: The calculated radiation risks are of a similar order of magnitude as are the risks the respective person is exposed to on the way to the medical examination or to the court. However, the applicability and the limits of the radiological procedures applied for age estimation require extensive and critical discussion.

Age Determination by Skeleton↗
PubMed2000

Comparison of patients' preferences and evaluations regarding aspects of general practice care.

BACKGROUND: Although patients' views on health care are perceived to be crucial, insight into the different constructs capturing these views remains limited. OBJECTIVE: The aim of this study was to determine the relationship between patients' preferences and their evaluations of general practice care. METHODS: Patients visiting five rural practices in The Netherlands were asked to complete a questionnaire measuring either their evaluations or their preferences on 44 aspects of general practice care. After at least 3 weeks, those patients who had answered the evaluation questionnaire received the questionnaire measuring their preferences, and vice versa. RESULTS: A total of 449 patients answered both questionnaires (response 70%). The longer the period after the consultation, the lower was the mean percentage of all 44 aspects rated as 'good' in the evaluation questionnaire (P = 0.006) and the higher was the mean percentage of all 44 aspects rated as 'very important' in the preference questionnaire (P = 0.046). The Spearman rank order correlation between the ranking of patients' evaluations and patients' preferences was 0.34, a low although significant correlation (P = 0.024), i.e. the two rank orders do not resemble each other very much. CONCLUSIONS: Patients clearly distinguished their preferences from their evaluations of general practice care. Aspects of general practice care, whether important or not, can be evaluated positively or negatively. Patients' preferences and patients' evaluations are, however, both influenced by the length of the time elapsed since the consultation.

Adolescent↗
PubMed2000

Pharmacokinetics of a sustained-release dosage form of clomipramine.

In this study, the pharmacokinetic parameters of the sustained-release (SR) dosage form of clomipramine (CMI) were compared with those obtained after the administration of the immediate-release (IR) dosage form. Two studies were performed. In the first study, a single oral dose of both products was administered in 12 healthy volunteers, and in the second study, multiple doses of both products were administered in 6 patients with depression in which steady-state plasma levels (Css) were determined. Plasma levels were assayed using an HPLC method. In the single-dose study, the mean Cmax and AUC values of CMI were 63.37 ng/mL-1 and 1375.38 ng.h/mL-1 for the reference product and 32.55 ng/mL-1 and 1285.26 ng.h/mL-1 for the test product, respectively. The mean beta and MRT values of CMI were 0.030 h-1 and 47.21 h for the reference product and 0.026 h-1 and 55.63 h for test product, respectively. Results showed that after the multiple-dose study, the mean clomipramine plus demethylclomipramine values of Cavss were 406.2 ng/mL-1 for the reference and 328.6 ng/mL-1 for the sustained-release dosage form. This product also presented less fluctuation in steady-state plasma levels (1.08 vs. 1.23). The values of MRT and tmax were higher for the SR dosage form, showing that the drug was maintained longer in the body. The mean values for the ratio metabolite/drug were 2.06 and 2.41 for the IR and SR dosage forms, respectively. Neither AUC nor elimination half-life was affected significantly after the administration of the sustained-release dosage form.

Adult↗