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H J Yu

Publications and source records attributed to H J Yu.

54 records · Page 3Linked to original sources
PubMed1996

Clinical efficacy of prostate-specific antigen testing in patients with prostate disease.

Prostate-specific antigen (PSA) has become the most commonly used marker for the detection of prostatic adenocarcinoma (PCa) in recent years. To understand the clinical value of PSA testing in patients with prostate disease, the preoperative serum PSA values of 562 patients who underwent prostatic surgery from April 1993 to December 1995 were correlated with histologic findings in samples taken during surgery. Histopathologic findings revealed 93 cases of PCa and 469 cases of benign prostatic hyperplasia (BPH). Of the 220 patients with a serum PSA level within the normal range (0-4 ng/mL), PCa was diagnosed in six (2.7%) cases. However, among the 342 patients (61%) who had serum PSA > 4.0 ng/mL, BPH was diagnosed in 225 (75%) patients. With a PSA cutoff value of 4.0 ng/mL, the sensitivity, specificity and positive predictive value of PSA in distinguishing PCa from BPH were 94%, 45% and 25%, respectively. Raising the cutoff value to 10 ng/mL enhanced the specificity (76%) and positive predictive value (42%) with a slight compromise in sensitivity (85%). Of the 469 patients with BPH, 255 (54%) had a serum PSA > 4.0 ng/mL and 107 (24%) had a serum PSA > 10.0 ng/mL. Prostate volume, histologically documented prostatic inflammation and history of urinary retention prior to PSA determination may partly explain the abnormal elevation of serum PSA in patients with BPH. Our data confirmed the sensitivity of PSA in the detection of PCa in a country with a low incidence of PCa. However, a considerable proportion of patients with BPH had elevated serum PSA levels caused by factors unrelated to malignancy. Raising the cutoff value of PSA or employing adjunct parameters derived from PSA determination may be helpful in improving the diagnostic efficacy of PSA.

Aged↗
PubMed1995

Determination and cellular localization of adenylyl cyclase isozymes expressed in embryonic chick heart.

Mammalian heart has been reported to express AC isozymes (types V and VI) that are inhibited by < microM [Ca2+]; avian heart has been reported to express adenylyl cyclase activity that is inhibited by < microM [Ca2]. We have used reverse transcription polymerase chain reaction (RT-PCR) to determine that type V and VI AC mRNAs are present in freshly isolated ventricular myocytes. Subsequent RNase protection assays revealed that that the type V signal is 4-5 times that for the type VI isozyme. In situ hybridization with high specific activity cRNA probes combined with immunocytochemistry with a chick anti-myosin antibody was used to probe the cellular origins of type V and type VI AC signals. These studies show that myocytes contain messages for both the type V and VI isozymes but that AC V is the major isoform. Interestingly, while the type V AC mRNA appears to be localized primarily, if not exclusively, in myocytes, the signal for type AC VI mRNA in non-myocytes is stronger than in myocytes.

Adenylyl Cyclases↗
PubMed1995

Effect of magnesium ions on rabbit detrusor contractility and intracellular free calcium.

Magnesium (Mg2+) is one of the most abundant ions in the body. In the human body, Mg2+ plays important roles including cofactors in many crucial enzyme systems, especially those involving energy transfer, storage and utilization. Alteration of the concentration of Mg2+ may cause neuromuscular hyperactivity, psychiatric disturbances, calcium/potassium abnormalities, and overactivity of cardiac muscle. Most information on the effect of Mg2+ on muscle contraction has been obtained from studies on cardiac, skeletal, and vascular muscle; much less is known about the effect of Mg2+ in other smooth muscle systems. In the current study, we investigated the effect of Mg2+ on the contraction and intracellular free calcium of rabbit urinary bladder detrusor muscle in response to carbachol and transmural field stimulation (FS). The results can be summarized as follows: (1) Reduction of the concentration of magnesium [Mg2+] from normal Tyrode's solution enhanced the spontaneous basal activity, whereas addition of Mg2+ gradually abolished this spontaneous activity. (2) Muscle contraction induced by FS or carbachol was enhanced in Mg(2+)-free Tyrode's solution. Addition of Mg2+ inhibited the response to both forms of stimulation in a dose-dependent manner. (3) Inhibitory effects of Mg2+ were potentiated when the Ca2+ concentration in the Tyrode's solution was reduced to 0.6 mM, whereas increasing the extracellular concentration of Ca2+ (5.4 mM) reduced the inhibitory effects of Mg2+. (4) Using FURA-2 to monitor intracellular free calcium simultaneous with contractile tension, we demonstrated that the alterations in the contractile responses observed at different concentrations of extracellular Mg2+ correlated with similar changes in intracellular free calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Relationship between serum prostate specific antigen concentration and prostate volume.

Serum prostate-specific antigen (PSA) levels and prostate volume were evaluated in 553 healthy men aged 40 to 79 years, who entered a study program for benign prostatic hyperplasia from December 1993 to August 1994. Digital rectal examination (DRE), transrectal ultrasonography (TRUS) and serum PSA assay were performed on all participants. After excluding men with suspected prostate cancer and incomplete data, 542 cases qualified for analysis. The mean serum PSA level was 1.4 +/- 1.7 ng/mL which increased with age from 0.8 +/- 0.9 ng/mL in men aged 40 to 49 years to 2.7 +/- 2.8 ng/mL in those aged 70 to 79 years. In this study group, 250 men (46.1%) were documented to have various degrees of benign prostatic hyperplasia (BPH). The prostate volume averaged 22.3 +/- 9.1 mL which increased from 18.5 +/- 6.1 mL in the fifth decade to 27.2 +/- 13.7 mL in the eighth decade. There was a modest correlation between serum PSA level and both age and prostate volume. However, when the prostate volume was adjusted, the PSA level correlated more weakly with age in a multivariate analysis. On the other hand, the serum PSA level correlated more strongly with prostate volume when age was adjusted. Although 5.4% of the men had serum PSA levels > 4 ng/mL, there was no evidence of prostate cancer by DRE and TRUS. Serum PSA levels increased with age and prostate volume, and correlated better with the latter. These factors should be taken into account when determining the significance of a given PSA value in a patient without clinical evidence of prostate cancer.

Adult↗
PubMed1994

Adenosine receptor-mediated inhibition of cardiac adenylyl cyclase activity may involve multiple receptor subtypes.

We previously reported that the adenosine receptor agonist N6-phenylisopropyladenosine (R-PIA) inhibits adenylyl cyclase in detergent-permeabilized embryonic chick ventricular myocytes in the presence of the adrenergic receptor agonist, isoproterenol (Ma and Green 1992). The slope of the dose response curve of this inhibition is very shallow (nH 0.3-0.4). The present studies on detergent-permeabilized chick myocytes evaluate the mechanisms underlying this shallow inhibition curve. We find that in contrast to R-PIA, two additional adenosine receptor agonists, N6-cyclopentyladenosine (CPA) and 2-chloro-N6-cyclopentyladenosine (CCPA), inhibit cardiac adenylyl cyclase activity in a monophasic, dose-dependent manner (nH approximately 1). Two A1 adenosine receptor antagonists, 8-cyclopentyl-1,3,-dipropylxanthine (CPX) and 3-(4-amino)phenethyl-1-propyl-8-cyclopentylxanthine (BW-A884U) affect the R-PIA responses differently. BW-A884U shifts the R-PIA dose response curve to the right in a parallel fashion while CPX both shifts the R-PIA response curve and increases its steepness. Cardiac A1 adenosine receptors were further characterized using one antagonist ([3H]CPX) and two agonist ([3H]R-PIA and [3H]CCPA) radioligands. [3H]CPX binds to the adenosine receptors in detergent-permeabilized ventricular myocytes with a Kd value of 3.3 +/- 0.2 nM and a BMAX value of 30.1 +/- 2.4 fmol/mg protein (means +/- SEM; N = 4). [3H]R-PIA detects more sites than [3H]CCPA (22.8 +/- 4.0 and 8.3 +/- 1.3 fmol/mg protein, respectively; GTP-free conditions). CPA and CCPA inhibit [3H]R-PIA binding in a shallow, dose-dependent manner (nH approximately 0.4), while R-PIA and CPA inhibit [3H]CCPA binding with a nH approximately 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclase Inhibitors↗
PubMed1994

Occupational asthma caused by chromium.

We report four cases of occupational asthma caused by chromium salts, three of whom showed dual and one isolated early asthmatic responses on specific chromium bronchoprovocation test (BPT). All of them were ex-smokers. Two showed positive skin-prick tests to 10 mg/ml of Cr2(SO4)3, but negative results on patch testing. The remaining two showed positive results on patch testing with Cr2(SO4)3. Three had airway hyperresponsiveness to methacholine on initial examination. Although initial methacholine airway challenge testing showed a negative result in the remaining patient, airway hyperresponsiveness developed transiently 24 h after an isolated immediate asthmatic reaction induced by chromium. Three patients were reassessed after complete avoidance of chromium. Two subjects showed marked improvement of their symptoms with significant increases of PC20 methacholine. We conclude that chromium induces occupational asthma in exposed workers. Further investigations are needed to clarify the pathogenetic mechanism.

Adult↗
PubMed1993

Effect of conduction distance on amplitude and area of compound action potentials of A fiber and C fiber.

We used 24 sacral dorsal roots of the rat to analyze amplitude and area changes of biphasic and monophasic compound action potentials (CAPs) at 4 conduction distances. Both the CAPs of the A-fiber and C-fiber were analyzed. The changes were examined with the paired t test and linear regression. All the variables decreased linearly with increasing conduction distance except area of monophasic CAP, which remained constant throughout. CAP data were also compared between the S1 and S2 roots by using the pooled t test. Only area of monophasic CAP showed good correspondence with the anatomical data. Therefore, area of monophasic CAP is suggested as the best parameter for representing the functional state of a nerve.

Action Potentials↗
PubMed1993

Calcium entry via L-type calcium channels acts as a negative regulator of adenylyl cyclase activity and cyclic AMP levels in cardiac myocytes.

It is well established that the inotropic effect of beta-adrenergic agonists is mediated by the stimulation of adenylyl cyclase activity and the subsequent phosphorylation of specific proteins by cAMP-dependent protein kinase. The L-type calcium channel is believed to be one of the proteins phosphorylated; the phosphorylation of calcium channels is believed to increase calcium entry into myocytes, which is, at least in part, responsible for the positive inotropic effect. The present studies show that the cAMP-elevating effect of isoproterenol is increased as extracellular calcium is lowered and that calcium channel blockers potentiate the cAMP-elevating effect of isoproterenol in the presence in extracellular calcium. This effect is not dependent on effects on cAMP catabolism and is not specific for beta-adrenergic receptors, because the cAMP-elevating effect of forskolin is similarly affected. Measurements of adenylyl cyclase activity in cardiac membranes show that submicromolar Ca2+ concentrations directly inhibit adenylyl cyclase activity. These results demonstrate that increased entry of Ca2+ via L-type calcium channels in response to beta-adrenergic receptor stimulation acts as a negative regulator of the effect of beta receptor stimulation on adenylyl cyclase activity.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1992

Characterization of a newly established human bladder carcinoma cell line, NTUB1.

A new human bladder cancer cell line, NTUB1, has been derived from the surgical specimen of a 70-year-old female patient diagnosed with poorly differentiated transitional cell carcinoma. It has been successfully propagated in vitro for over 24 months without evidence of reaching senescence. Population doubling time was about 21 hours at the 32nd passage. It was tumorigenic in nude mice, and the histologic findings of the heterotransplanted tumor resembled the original tumor. Expression of keratin proteins confirmed its epithelial origin. Cytogenetic analysis showed multiple chromosome changes. Anticancer drugs, including thiotepa and adriamycin, were tested in vitro, and the cytotoxicity did not exceed 50% of the control value; likewise, in this patient chemotherapy was not effective. On the other hand, a combination of recombinant tumor necrosis factor and interferon tau in vitro was more effective against this tumor.

Aged↗
PubMed1992

[Diagnostic value of suspect epilepsy by means of 24 hour of ambulatory electroencephalogram].

106 cases of suspect epilepsy random observed by means of 24 hr tape recording of AEEG were given in this paper. Among them 57 cases. (accounting for 53.77%) are lightly abnormal including 42 cases (accounting for 39.62%) recorded as epilepsy burst. Comparing with EEG: Among 93 cases 25 cases as lightly abnormal by EEG (accounting for 26.88%), 52 cases recorded as lightly abnormal by AEEG (accounting for 55.91%) (P less than 0.005); arising rate of epilepsy burst 11 cases were recorded by EEG (accounting for 11.82%), 41 cases by AEEG (accounting for 44.01%) (P less than 0.005). The record of epilepsy burst patients monitored showed that positive rates of transient consciousness loss (8/15, 53.33%) and convulsions (9/19, 47.39%) are the highest. Abnormal burst time by AEEG is during sleeping (54 cases observed accounting for 77.14%) with positive rate highest at the same time, most accorded in the front temporal area (29/92, 31.52%). The author therefore, suppose that AEEG is more accurate to find abnormal bast wave or epilepsy burst wave than EEG because of superior condition in recording time to EEG and could offer more objective diagnosis reference for suspect epilepsy patients who are difficult to be checked clinically because of low positive rate of EEG.

Adolescent↗
PubMed1991

A modified "triangular pulse" stimulator for C-fibers stimulation.

A low-cost, battery-powered stimulator is described. This device generates asymmetric current pulse with fast rising phase and slower exponential decay. The current intensity and the time constant of the exponential decay can be independently and continuously varied. An example of using this stimulator to selectively activate C-fibers is demonstrated. In this case the total charge injected in one stimulation is only 67 nanocolumb, which is much smaller than that injected by conventional DC polarization technique. Detailed information about the circuit design is described.

Animals↗
PubMed1987

Cytoplasmic effect on gene function in Xenopus laevis.

The pigmentation gene of Xenopus laevis is dominant and that of albino aP mutant recessive. Heterologous haploid hybrids are produced by UV inactivation of the egg nuclei during second polar body formation in the mutant sperm-fertilized Xenopus eggs. During development of these hybrids, melanin appeared in the eye and melanophores in the skin at stages comparable to those of the wild type, but much earlier than in the albino mutant. The number and intensity of pigment cells are intermediate between the black Xenopus and albino mutant. While a number of pigment cells remain in the hybrids, those in the albino eventually degenerate. Therefore, the development and maintenance of pigmentation in heterologous hybrids are contributed by Xenopus cytoplasm. Tadpole tail-tips were squashed and stained for chromosome counting. The results show that Xenopus and mutants are diploid (36 chromosomes) and heterologous haploid hybrids have 18 chromosomes.

Animals↗
PubMedDate not supplied

Rates of health services utilization and survival in patients with heart failure in the Department of Veterans Affairs medical care system.

The objective of this study was to describe patterns of hospital and clinic use and survival for a large nationwide cohort of patients with heart failure. A retrospective cohort study of patients treated in the Veterans Affairs medical care system was conducted using linked administrative databases as data sources. In 1996, the average heart failure cohort member had 1-2 hospitalizations, 14 inpatient days, 6-7 visits with the primary physician, 15 other visits for consultations or tests, and 1-2 urgent care visits per 12 months. The overall risk-adjusted 5-year survival rate was 36%. Hospital use rates in the cohort fell dramatically between 1992 and 1996. One-year survival rates increased slightly over the period. Patients with heart failure are heavy users of services and have a very poor prognosis. Utilization and outcome data indicate the need for major efforts to assure quality of care and to devise innovative ways of delivering comprehensive services.

Adult↗
PubMedDate not supplied

Results of immunochemo-surgery for gastric carcinoma.

BACKGROUND/AIMS: Although the therapeutic results of gastric cancer have markedly improved, it still remains the most common cancer death in Korea. METHODOLOGY: The clinicopathologic characteristics were analyzed for 11,491 consecutive patients who underwent operation for gastric cancer at the Department of Surgery, Seoul National University Hospital from 1971 to 1997. We also evaluated the survival and prognostic factors for 9,262 consecutive patients from 1981 to 1996. The prognostic significance of treatment modality [surgery alone, surgery + chemotherapy, surgery + immunotherapy + chemotherapy (immunochemo-surgery)] were evaluated in stage III gastric cancer. RESULTS: The 5-year survival rate of overall patients was 55.8%, and that of patients who received curative resection was 64.8%. The 5-year survival rates according to TNM stage were 92.9% for Ia, 84.2% for Ib, 69.3% for II, 45.8% for IIIa, 29.6% for IIIb and 9.2% for IV. Depending on the extent of resection, the 5-year survival rates were 68.7% for STG, 45.4% for TG, 19.6% for combined resection and there was no 5-year survivor in the nonresection group. Regarding adjuvant treatment modality, significant survival difference was observed in stage III patients. The 5-year survival rates were 44.8% for the immunochemo-surgery group, 36.8% for the surgery + chemotherapy group and 27.2% for the surgery alone group. CONCLUSIONS: Curative resection, depth of invasion and lymph node metastasis were the most significant prognostic factors in gastric cancer. Consequently, early detection and curative resection with radical lymph node dissection, followed by immunochemotherapy especially in patients with stage III gastric cancer should be recommended as a standard treatment principle for patients with gastric cancer.

Adenocarcinoma↗
PubMedDate not supplied

Therapeutic effects of finasteride in benign prostatic hyperplasia: a randomized double-blind controlled trial.

The clinical effects of finasteride, a 5 alpha-reductase inhibitor, in patients with benign prostatic hyperplasia (BPH) were evaluated in a double-blind, placebo-controlled study. Forty-six patients with symptomatic BPH were randomly assigned to 2 groups, the finasteride group and the placebo group. The finasteride group received 5 mg of finasteride daily for 6 months. Prostate volume, urinary flow, urinary symptoms, serum prostate-specific antigen (PSA) and adverse events were determined before and after treatment. After 6 months of treatment the patients treated with 5 mg of finasteride per day had a 30% decrease in their total urinary symptom score, a 14% decrease in prostate volume and a 0.9 ng/dL decrease of PSA. Their maximal urinary flow rate increased by 1.42 mL per second and the mean urinary flow rate increased by 0.64 mL per second. The patients given placebo showed no significant changes in their prostate volume, serum PSA and maximal and mean urinary flow rate. However, the symptom scores in the placebo group also decreased significantly. When compared with the placebo group, those in the finasteride group had significantly lower prostate volume, serum PSA, maximal urinary flow rate and urinary symptoms, but not mean urinary flow rate. The frequency of adverse events was low in both the finasteride and placebo groups. These results show that finasteride may be an effective and safe alternative for the treatment of patients with BPH.

Aged↗