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Biomedical subjects

Y M Chen

Publications and source records attributed to Y M Chen.

At least 145 records · Page 8Linked to original sources
PubMed1995

Breathing-coordinated exercise improves the quality of life in hemodialysis patients.

Breathing-coordinated exercise is a traditional Chinese exercise. These exercise maneuvers consist of slow diaphragmatic breathing, end-inspiratory pause, and Kegel's exercise. A total of 30 patients were enrolled in this study, with 12 patients as controls, to evaluate its effect on hemodialysis patients. Exercise was performed for 25 to 30 min twice a day for at least 3 months. Results from the exercise group showed a subjective improvement in appetite and physical strength, and an increase in the frequency of bowel movements, in addition to enhanced sexual activity and a significant increase in Karnofsky scores. Six patients in the exercise group underwent bicycle ergometry and demonstrated a stable maximal oxygen consumption, whereas the control group revealed a decline in maximal oxygen consumption. Photoelectric plethysmography and laser-Doppler flowmetry demonstrated a pulsatile enhancement of the peripheral microcirculation. Abdominal sonography revealed an oscillatory change in the diameter of the inferior vena cava. It was concluded that these gentle exercise maneuvers may improve the quality of life in hemodialysis patients, especially weak dialysis patients. The mechanism may be partly related to an improvement in microcirculation.

Adult↗
PubMed1995

Leukemoid reaction resulting from multiple cytokine production in metastatic mucoepidermoid carcinoma with central necrosis.

We report a male patient with metastatic high-grade mucoepidermoid carcinoma and associated leukemoid reaction. The patient was transferred to our hospital due to persistent spiking fever, marked granulocytosis, and suspected liver abscess. After thorough bacteriological studies, including cultures of blood and material aspirated from the "liver abscess", no evidence of infection was documented. The patient suffered from persistent spiking fever for more than 4 weeks in spite of empirical antibiotic treatment, and repeated aspiration of the presupposed liver abscess. He underwent exploratory laparotomy for intended surgical evacuation of the liver abscess and bacteriological diagnosis. The operative findings were compatible with metastatic carcinoma with multiple liver and retroperitoneal lymph node involvement and tumor necrosis. The pathology report indicated high-grade mucoepidermoid carcinoma. Immunohistochemistry showed positive staining for interleukin-1 alpha (IL-1 alpha) and IL-6. Elevation of cytokine levels in the necrotic tumor fluid, including IL-1 alpha, IL-6, granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor was confirmed by ELISA test. This case shows that multiple cytokine production from a metastatic tumor and its central necrotic area in the liver can produce a febrile leukemoid reaction mimicking a pyogenic liver abscess.

Abdominal Neoplasms↗
PubMed1995

The prognostic value of serum cytokine levels in patients with acute infections.

BACKGROUND: Elevation of serum cytokine level, especially tumor necrosis factor-alpha (TNF-alpha) and granulocyte-colony stimulating factor (G-CSF), has been reported in acute bacterial infection. Elevation of serum TNF-alpha level upon patients' admission has also been reported to correlate with the fatal outcome. METHODS: The present study is to evaluate, in addition to TNF-alpha and G-CSF, whether serum stem cell factor (SCF), interleukin-3 (IL-3) and granulocyte-macrophage-CSF (GM-CSF) levels to see if they were also elevated in patients with acute bacterial infection. It also tries to evaluate whether different degree of elevation of cytokine levels had any relationship to patients' clinical parameter, including fatality. Correlation between different kinds of cytokines was also studied. RESULTS: Patients with bacterial growth in blood culture had higher level of serum G-CSF. Higher level of serum TNF-alpha was significantly associated with the occurrence of septic shock, but not of fatal outcome. Low serum G-CSF and high serum SCF level were significantly associated with fatal outcome; however, all the patients still had serum SCF levels within normal range. GM-CSF and IL-3 play no obvious role as systemic effector molecule in acute bacterial infection. CONCLUSIONS: Higher levels of serum TNF-alpha are associated with the occurrence of septic shock. Low serum G-CSF levels are significantly associated with fatal outcome. Routine monitoring of serum G-CSF level in patients with severe infection in order to supplement recombinant G-CSF can possibly help patients to overcome the disaster.

Acute Disease↗
PubMed1995

Superior vena cava syndrome revisited.

A clinical review with analysis of prognostic factors, including the impact of the initial management modality, was conducted on 137 patients with superior vena cava syndrome (SVCS) seen at the Veterans General Hospital-Taipei between 1989 and 1993. Malignant diseases account for most of the SVCS in our Chinese patients. Patients received diagnostic intervention for their underlying diseases without obvious complications. Whether or not there is a development of SVCS in lung cancer patients, showed prognostic significance in non-small cell lung cancer (NSCLC) and no significance in small cell lung cancer (SCLC). Those with SVCS as the initial manifestation of malignant disease had a poor prognosis compared to those who developed SVCS later. Survival is best in lymphoma/leukemia patients, followed by malignant thymoma and SCLC, and worst in NSCLC and metastatic cancer. The rapid onset of symptoms from SVCS had a short median survival in lung cancer and significantly compromised survival in SCLC. The overall survival of SCLC with SVCS was not affected, regardless of whether the initial therapy had been radiotherapy or chemotherapy.

Adult↗
PubMed1995

Metastatic nasopharyngeal carcinoma with epidural spinal cord compression: report of an unusual and catastrophic event.

Nasopharyngeal carcinoma (NPC) with epidural metastasis of spinal cord has rarely been reported. We present an NPC patient with epidural spinal cord compression due to metastasis. In spite of emergent radiotherapy and large dose decadron treatment, this patient still had severe sequela of paraplegia and incontinence. The epidemiology, clinical findings, diagnosis, treatment and outcome of this metastatic epidural tumor compression were discussed.

Carcinoma, Squamous Cell↗
PubMed1995

Elevation of serum IL-6 levels in patients with acute bacterial infection.

BACKGROUND: Serum cytokine levels have been reported to elevate in acute bacterial infection, but the relationship of differential elevation in cytokine levels to patients' clinical parameters and prognosis remains controversial. The present study was designed to evaluate whether serum interleukin-1 alpha (IL-1 alpha) and IL-6 levels were raised in patient with acute bacterial infection, and were correlated with patients clinical parameters. METHODS: Thirty patients, aged from 20 to 91 years, calling our emergency room with clinical evidence of acute bacterial infection and marked leukocytosis, were enrolled in this study. Sera were collected immediately and analyzed for IL-1 alpha and IL-6 levels with Enzyme-Linked Immunosorbent Assay (ELISA) method. RESULTS: All patients with acute bacterial infection had measurable higher levels of serum IL-6 than normal volunteers. Patients with higher serum IL-6 level were more likely to have fever, though without statistical significance (p = 0.09). Serum IL-6 levels did not correlate significantly with positive blood culture result, septic shock, or fatal outcome. Serum IL-1 alpha levels were below minimal detectable concentrations in all patients checked. CONCLUSIONS: Serum IL-6 levels were elevated in patients with acute bacterial infection, and were possibly associated with the occurrence of fever. IL-1 alpha played no obvious role as systemic effector molecule in acute bacterial infection in our study.

Acute Disease↗
PubMed1995

A recombinant rice 16.9-kDa heat shock protein can provide thermoprotection in vitro.

It is difficult to obtain large amounts of purified low-molecular-mass heat shock proteins (LMM HSPs), which are unique to plants, for biochemical and physiological studies. Therefore, an attempt was made to produce such a HSP by applying recombinant DNA technology. We fused the cDNA for a rice class I 16.9-kDa HSP, pTS1, to the gene for glutathione S-transferase (GST) of Schistosoma japonicum and we obtained large amounts of the fusion protein from transformed Escherichia coli cells. In addition, we found that the 16.9-kDa HSP obtained by cleavage of the recombinant protein could also form a protein complex of approximately 310 kDa under nondenaturing conditions as can the small, native, class I HSPs from heat-shocked rice seedlings. An assay in vitro to examine the thermoprotection of rice soluble proteins from heat denaturation revealed the strong stabilizing effect of the recombinant HSP.

Amino Acid Sequence↗
PubMed1994

Construction of Tn917ac1, a transposon useful for mutagenesis and cloning of Bacillus subtilis genes.

A Tn917 derivative was constructed for the purposes of mutagenesis and cloning of Bacillus subtilis genes. This transposon, Tn917ac1 (4.6 kb), consisted of terminal inverted repeats of Tn917, the res sequence, a ColE1 origin of replication (ori) and two drug-resistance genes. The plasmid carrying this transposon, named pD917, contained the erm-tnpR-tnpA gene cluster of Tn917 and a temperature-sensitive ori of pE194. For the purpose of mutagenesis, transposition of Tn917ac1 was induced by culturing strains harboring pD917 in a medium containing a low concentration of erythromycin. Cells with a Tn917ac1 insertion in the chromosome were selected on agar containing chloramphenicol after heat treatment to eliminate the plasmidic form of pD917. DNA fragments adjacent to Tn917ac1 could be cloned by restriction digestion of the chromosomal DNA and by transforming the self-ligated restriction fragments into Escherichia coli. Sequence analysis revealed that Tn917ac1 was integrated into the chromosome of B. subtilis by transposition in a recE strain and by transposition or integration of pD917 in a wild-type strain. Tn917ac1 has been demonstrated to be useful for mutating and cloning of the genes involved in the biosynthesis of fengycin in B. subtilis F29-3.

Bacillus subtilis↗
PubMed1994

Poly(ADP-ribose) polymerase in plant nuclei.

We show that poly(ADP-ribose) polymerase is present in maize, pea and wheat nuclei. We have identified the enzyme product as poly(ADP-ribose) by purification and electrophoresis on a DNA sequencing gel. This reveals a polymer ladder consisting of up to 45 residues. The polymer product from maize, after digestion with snake venom phosphodiesterase, gave only 5'-AMP and (phosphoribosyl)-AMP; the mean chain length of the polymer was 5 and 11 residues in two separate experiments. The optimum pH of the plant enzyme is greater than pH 7.0 in pea, wheat and maize; the optimum temperature for enzyme activity is approximately 15 degrees C. The Km for NAD+ for the enzyme from maize is estimated to be approximately 50 microM under optimal conditions. Several compounds (nicotinamide, deoxythymidine, 3-aminobenzamide, 3-methoxybenzamide and 5-bromodeoxyuridine) that specifically inhibit the animal enzyme also inhibit the enzyme from plants. The ratio of the IC50 for 5-bromodeoxyuridine to the IC50 for 3-aminobenzamide in maize is similar to that of the animal enzyme indicating that the enzyme involved is poly(ADP-ribose) polymerase and not mono(ADP-ribosyl) transferase. SDS gel electrophoresis and gel filtration analysis of a crude extract of maize nuclei indicate a molecular mass for poly(ADP-ribose) polymerase of approximately 114 kDa.

ADP Ribose Transferases↗
PubMed1994

Isolation and characterization of simian T-cell leukemia virus type II from New World monkeys.

Since the description of human T-cell leukemia virus type I (HTLV-I) and its simian counterpart, simian T-cell leukemia virus type I (STLV-I), the possible existence of other related simian retroviruses has been raised. Here, we report a new retrovirus, STLV-II, which we have identified in spider monkeys (Ateles fusciceps), a New World primate species. Initially, a recombinant HTLV-II envelope protein (RP-IIB) was used to identify anti-STLV-II antibodies in New World monkeys by Western blot (immunoblot) assays. Subsequently, the virus was characterized by Southern blot hybridization, which showed that STLV-II and HTLV-II have a high degree of nucleotide sequence homology but have different restriction enzyme patterns. Nucleotide sequence analysis of the pX-II region of STLV-II provirus revealed 3% variation with the corresponding region of HTLV-II. Electron micrographic studies revealed HTLV-like, type C retrovirus particles outside the cell membranes of STLV-II-infected cells. This study describes the first link between HTLV-II and a simian reservoir in the New World. Further molecular studies of STLV-II infection in different species of New World monkeys, especially from the wild, may provide valuable information about the origin and intragroup relationships of South American monkeys. Spider monkeys infected with STLV-II may serve as an important animal model for HTLV-II infection in humans.

Animals↗
PubMed1994

Detection of interactions between myogenic and TGF mechanisms using nonlinear analysis.

Previous studies using linear techniques have provided valuable insights into the dynamic characteristics of whole kidney autoregulation and have led to the general conclusion that the myogenic mechanism and tubuloglomerular feedback (TGF) are highly nonlinear control mechanisms. To explore further the dynamic nature of these nonlinear autoregulatory mechanisms, we introduce the technique of nonlinear modeling using Volterra-Wiener kernels. In the past several years, use of Volterra-Wiener kernels for nonlinear approximation has been most notably applied to neurophysiology. Recent advances in algorithms for computation of the kernels have made this technique more attractive for the study of the dynamics of nonlinear physiological systems, such as the system mediating renal autoregulation. In this study, the general theory and requirements for using this technique are discussed. The feasibility of using the technique on whole kidney pressure and flow data is examined, and a basis for using the Volterra-Wiener kernels to detect interactions between physiological control mechanisms is established. As a result of this method, we have identified the presence of interactions between the oscillating components of the myogenic and the TGF mechanisms at the level of the whole kidney blood flow in normotensive rats. An interaction between these oscillatory components had previously been demonstrated only at the single-nephron level.

Animals↗
PubMed1994

Human cardiovascular response to sympathomimetic agents during head-down bed rest: the effect of dietary sodium.

Changes in sympathoadrenal function and cardiovascular deconditioning have long been recognized as a feature of the physiological adaptation to microgravity. The deconditioning process, coupled with altered hydration status, is thought to significantly contribute to orthostatic intolerance upon return to Earth gravity. The cardiovascular response to stimulation by sympathomimetic agents before, during, and after exposure to simulated microgravity was determined in healthy volunteers equilibrated on normal or high sodium diets in order to further the understanding of the deconditioning process.

Adult↗
PubMed1994

Blood pressure, circulating atrial natriuretic peptide and sodium excretion responses during acute saline infusion in patients with essential hypertension.

In order to examine whether changes in circulating atrial natriuretic peptide (ANP) and sodium excretion during saline infusion in patients with essential hypertension (EH) could be modulated by the severity of resting arterial blood pressure (BP), 30 subjects with EH and nine normotensive subjects were given 2 L of isotonic saline infusion at a rate of 500 mL/hour. Plasma ANP concentrations in EH increased significantly from 64.9 +/- 5.1 (mean +/- SEM) to 92.5 +/- 12.8 pg/mL at the first hour and peaked at the second hour. In normotensives, the increase of plasma ANP was not significant until the fourth hour of infusion. Hypertensive subjects sustained a greater percentage increment of mean BP (MBP) than normotensives at the end of infusion. Those with pre-saline MBP exceeding 107 mmHg (group A) exhibited a faster and greater rise in plasma ANP after saline loading than those having less than or equal to 107 mmHg (group B). The post-saline four-hour natriuresis was appreciably higher in group A than group B, while the percentage increment of MBP at the fourth hour was significantly greater in the latter as compared to normal controls. These results indicate that patients with higher basal arterial pressure attain a faster and greater ANP response following saline infusion than those with lower BP. This phenomenon may be responsible for the maintenance of short-term fluid-volume and BP homeostasis during acute sodium loading in established EH.

Adult↗
PubMed1994

Pleural and pericardial mesothelioma in a general teaching hospital during the last fourteen years.

BACKGROUND: Mesothelioma is not common in Taiwan; its clinical manifestations and biological behavior in the Chinese patients have thus rarely been discussed. METHODS: The chart records of mesothelioma patients collected from 1979 to 1992 in Veterans General Hospital-Taipei were retrospectively reviewed. RESULTS: Sixteen thoracic mesotheliomas were diagnosed in 15 patients, including 5 benign fibrous mesotheliomas, 1 malignant pericardial mesothelioma and 10 malignant pleural mesotheliomas. One patient suffered from benign fibrous mesothelioma initially, and the disease transformed into malignant mesothelioma 5 years later. Symptoms of benign fibrous mesothelioma were nonspecific and all 5 cases occurred in lower pleural cavities. One case presented with repeated hypoglycemic coma and the initial diagnosis was hepatoma. History of asbestos exposure probably occurred in 3 of 10 malignant pleural mesotheliomas. The median survival of malignant pleural mesothelioma after onset of symptoms was 14 months. Survival seemed better in epithelial type and those who received surgical treatment of malignant mesothelioma. CONCLUSIONS: The symptoms of mesothelioma were nonspecific. Benign fibrous mesothelioma should be considered in patients with palpable liver and hypoglycemic symptoms. Malignant transformation can occur in benign fibrous mesothelioma. Survival of malignant mesothelioma seems better in epithelial type and in those who received surgical treatment.

Adult↗
PubMed1994

Plant low-molecular-mass heat-shock proteins: their relationship to the acquisition of thermotolerance in plants.

Among the heat-shock proteins (HSPs) induced in response to heat-shock (HS) in all organisms, the low-molecular-mass (LMM) HSPs are the most abundant and unique in plants. The HSP genes at the transcriptional and the translational levels have been well-characterized; however, relatively little is known about the physiological function of HSPs. We have been studying the biological role of plant LMM HSPs based on the suggestion by Minton, Karmin, Hahn and Minton ([1982] Proc. Natl. Acad. Aci. U.S.A. 79, 7107-711) that HSPs may act as heat-stable proteins to non-specifically stabilize other proteins which are highly susceptible to inactivation or denaturation by heat. For the future, LMM-HSP gene transfer into organisms that do not synthesize plant LMM HSPs would be a way of determining the function of LMM HSPs, and success could be of practical importance.

Amino Acid Sequence↗
PubMed1993

On the efficacy of linear system analysis of renal autoregulation in rats.

In order to assess the linearity of the mechanisms subserving renal blood flow autoregulation, broad-band arterial pressure fluctuations at three different power levels were induced experimentally and the resulting renal blood flow responses were recorded. Linear system analysis methods were applied in both the time and frequency domain. In the frequency domain, spectral estimates employing FFT, autoregressive moving average (ARMA) and moving average (MA) methods were used; only the MA model showed two vascular control mechanisms active at 0.02-0.05 Hz and 0.1-0.18 Hz consistent with previous experimental findings [Holstein-Rathlou et al., Amer. J. Physiol., vol. 258, 1990.]. In the time domain, impulse response functions obtained from the MA model indicated likewise the presence of these two vascular control mechanisms, but the ARMA model failed to show any vascular control mechanism at 0.02-0.05 Hz. The residuals (i.e., model prediction errors) of the MA model were smaller than the ARMA model for all levels of arterial pressure forcings. The observed low coherence values and the significant model residuals in the 0.02-0.05 Hz frequency range suggest that the tubuloglomerular feedback (TGF) active in this frequency range is a nonlinear vascular control mechanism. In addition, experimental results suggest that the operation of the TGF mechanism is more evident at low/moderate pressure fluctuations and becomes overwhelmed when the arterial pressure forcing is too high.

Animals↗