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Biomedical subjects

M Yeh

Publications and source records attributed to M Yeh.

At least 37 records · Page 2Linked to original sources
PubMed1997

Nonselective beta-adrenergic blockade with carvedilol does not hinder the benefits of exercise training in patients with congestive heart failure.

BACKGROUND: Long-term beta-adrenergic blockade does not appear to be associated with drug-induced training in patients with congestive heart failure (CHF); whether exercise training can increase peak aerobic capacity in patients with CHF who are treated with beta-adrenergic blockers is currently unknown. METHODS AND RESULTS: We studied 23 patients with CHF who were treated with carvedilol or propranolol in addition to ACE inhibitors, furosemide, and digoxin. Of the patients treated with carvedilol, 8 underwent exercise training and 8 remained sedentary. All 7 patients treated with propranolol underwent exercise training. Peak oxygen consumption (mL.kg-1.min-1) was serially measured in trained and sedentary patients. Peak reactive hyperemia (mL.min-1.100 mL-1) was determined in the calf and forearm immediately before and after 12 weeks of training. The peak oxygen consumption of trained patients treated with either carvedilol or propranolol increased from 12.9 +/- 1.4 to 16.0 +/- 1.6 (P < .001) and 12.4 +/- 1.0 to 15.7 +/- 0.9 (P < .001) mL.kg-1.min-1, respectively, whereas it did not change in the sedentary patients. Peak reactive hyperemia increased significantly in the calves but not the forearms of trained patients. CONCLUSIONS: Long-term, nonselective beta-adrenergic blockade with carvedilol or propranolol does not prevent patients with CHF from deriving systemic and regional benefits from physical training.

Adaptation, Physiological↗
PubMed1997

Dissociation between upper and lower neck N13 potentials following paired median nerve stimuli.

Cervical N13 potential in response to the median nerve stimulation can be recorded either from upper (Cv2) or lower (Cv6) neck with almost equal amplitudes and latencies. It has long been debated whether they represent the same or different generator sources. Using a conditioning-test paired stimuli paradigm, we examined the differences of recovery function of Cv2- and Cv6-N13, anterior neck (AN)-P13, and scalp recorded P13/P14 in 6 healthy subjects. All cervical electrodes were referenced to the non-cephalic site. Scalp response was recorded with linked ear reference. The inter-stimulus intervals ranged from 4 to 20 ms with 2 ms increments. Throughout 4 to 18 ms ISI, Cv6-N13, AN-P13 and scalp P13/P14 were suppressed, whereas Cv2-N13 was facilitated. All but scalp P13/P14 returned close to the control at 20 ms ISI. The findings indicate that Cv2-N13, Cv6-N13 and scalp P13/P14 are independent each other and arise from different generator sources. The suppression of Cv6-N13 is consistent with a postsynaptic nature of this potential and may indeed be mediated through dorsal horn interneurons creating a current field orientation in the posterior-anterior direction. The facilitation of Cv2-N13 suggests that this is a presynaptic potential and may travel through the dorsal column with vertical orientation. The longer period of suppression of scalp P13/P14 suggests it to be of polysynaptic origin and to arise at least rostral to the cuneate nucleus.

Adult↗
PubMed1997

Construction and diversity analysis of a murine IgE phage surface display library.

To make further investigation of the IgE antibody repertoire in Trichosanthin (TCS) allergic responses, a murine IgE phage surface display library was constructed (3.0 x 10(5) independent clones). We first constructed the V epsilon cDNA library (4.6 x 10(5) independent clones) and V kappa cDNA library (3.0 x 10(5) independent clones). Then, the V epsilon and V kappa gene segments were amplified from both libraries by PCR respectively, and assembled into Fab fragment by SOE PCR. The phage library containing Fabs was thus constructed. The diversity of V epsilon from this library was analyzed and proved. Fab clones with high specificity to TCS have been screened out.

Animals↗
PubMed1997

Structural analysis and molecular modeling of two anti-trichosanthin IgE clones from phage antibody library.

Recently we constructed a murine IgE phage surface display library and screened out two IgE (Fab) clones with specific binding activity to Trichosanthin (TCS). In this work, the V epsilon and V kappa genes of the two clones were sequenced and their putative germline gene usages were studied. On the basis of the known 3D structure of Trichosanthin and antibody, molecular modeling was carried out to study the antigen-antibody interaction. The possible antigenic determinant sites on the surface of TCS recognized by both the clones were analyzed, and the reaction forces between TCS and two Fab fragments were also analyzed respectively.

Animals↗
PubMed1997

[Cloning of variable region genes of anti-tetanus toxoid antibody and their expression as three kinds of engineered antibodies in E. coli].

The heavy and light chain variable region genes of anti-tetanus toxoid (TT) antibody and the heavy chain Fd genes were amplified and cloned through RT-PCR from mouse hybridoma cells. The sequences of VH and VK were determined. Fd gene fragments were expressed in E. coli. The ELISA results indicated that the expressed Fd showed antigen binding activity but was nonspecific. Furthermore, through SOE and PCR techniques, the VH and VK gene fragments together with ScFv linker were assembled into single chain antibody (ScFv) gene fragment. While together with human heavy chain CH 1 gene fragment and Fab linker, they were assembled into chimeric Fab gene fragment. The two assembled gene fragments were separately inserted into phagemid pHEN 1, which was a fd-based vector containing gene 3 encoding the minor coat protein. In presence of helper phage M 13-VCS the anti-TT phage-ScFv or phage-Fab were displayed on the surface of phage particles respectively. Results from phage-ELISA indicated that both phage antibodies were TT-specific.

Amino Acid Sequence↗
PubMed1997

Temperature-induced expression of human-mouse chimeric Fab.

The temperature-induced expression vector pHZ01 with lambda PRPL promoter for the efficient expression of human-mouse chimeric Fab was constructed. Three kinds of chimeric Fab were expressed in E. coli: anti-prostate specific antigen (PSA) chimeric Fab, anti-lysozyme (HEL) chimeric Fab, and anti-tetanus toxoid (TT) chimeric Fab. All the soluble chimeric Fabs expressed showed specific antigen-binding activities.

Animals↗
PubMed1997

Thromboelastographic study of thrombosis in the implantable central venous access device.

BACKGROUND: In the present study thromboelastography (TEG) was to study whether or not hypercoagulopathy might contribute to the thrombosis of implantable central venous access device (Port-A-Cath, Pharmacia) in cancer patients. METHODS: All 76 oncological patients who were enrolled in this study had their R time, alpha angle and MA value measured before Port-A-Cath implantation, of whom 11 patients received re-implantation because of thrombotic device. We compared the measurements of these 11 patients (thrombotic group) with that of 65 patients (control group) who received Port-A-Cath implantation for the first time. According to TEG values the hemostatic status in these patients was classified as hypercoagulable, normal or hypocoagulable for comparison. All patients in the control group were followed up for 3 months for occurrence of thrombosis. RESULTS: It was found that no patient in the thrombotic group was associated with hypercoagulopathy. Five patients (7.5%) in the control group was found in hypercoagulable status at the time of catheter insertion but none of them developed clinical thrombosis during three months of observation. There was no significant difference between the two groups for R time, alpha angle but a higher MA value was found in the control group (p < 0.05). Furthermore, the hypercoagulability (7.5% for the control vs. none for the thrombotic group), hypocoagulability (1.5% vs. 9.1%) and normocoagulability (91.0% vs. 90.9%) were not statistically different between the two groups (Fisher exact test, P = 0.229). CONCLUSIONS: We conclude that hypercoagulopathy in cancer patients has little, if any, contribution in thrombosis of the implantable central venous access device.

Adult↗
PubMed1996

Diagnosing narcolepsy through the simultaneous clinical and electrophysiologic analysis of cataplexy.

OBJECTIVE: To demonstrate the utility of accurate clinical and electroencephalographic characterization of provoked cataplexy spells in the diagnosis of narcolepsy. METHODS: Four individuals, three with suspected and one with known narcolepsy, were clinically assessed during split-screen, video polysomnographic monitoring sessions after cataplectic events were induced by emotional provocation. RESULTS: The subjects experienced a total of nine cataplectic-like events, one occurring spontaneously (sleep paralysis) in association with a hypnagogic hallucination. During all events, the patients appeared to be sleeping with polysomnographic rapid eye movement sleep patterns, but when questioned they were able to give appropriate verbal responses. The diagnosis of narcolepsy was substantiated in all cases using standard overnight polysomnograms and multiple sleep latency tests. CONCLUSION: The diagnosis of narcolepsy can be greatly enhanced by documenting cataplexy with thorough clinical assessment and demonstration of typical rapid eye movement sleep patterns during provoked spells in the course of polysomnographic monitoring sessions.

Adolescent↗
PubMed1996

Topographic analyses of somatosensory evoked potentials following stimulation of tibial, sural and lateral femoral cutaneous nerves.

Using topographic maps, we studied the scalp field distribution of somatosensory evoked potentials (SEPs) in response to the stimulation of the tibial (TN), sural (SN) and lateral femoral cutaneous (LFCN) nerves in 24 normal volunteers. Cortical peaks, i.e., N35, P40, N50 and P60 were generally dominant in the contralateral hemisphere for the LFCN-SEP, whereas all peaks except N35 had dominance in the ipsilateral hemisphere to TN- and SN-SEPs. The findings imply that ipsilateral or contralateral peak dominance for the lower extremity SEP is determined by where the cortical leg representation occurs. As a result, mesial hemisphere representation results in peak dominance projected to the hemisphere ipsilateral to stimulation. Representations at the superior lip of the interhemispheric fissure or lateral convexity lead to midline or contralateral peak dominance. These findings also suggest that the paradoxically lateralized P40 is not the result of a positive field dipole shadow generated by the primary negative wave in the mesial hemisphere, but is the primary positive wave, analogous to P26 of the median nerve SEP. Accordingly, contralaterally dominant N35 is likely equivalent to the first cortical potential of N20 in the median nerve SEP. The difference in vector directions of potential fields between N35 and P40 may account for the opposite hemispheric dominance for these peaks in TN- and SN-SEPs.

Adult↗
PubMed1996

Effects of exogenous cytokines on the ethanol-mediated suppression of murine thymocyte proliferation.

Although attempts have been made to assess the effect of ethanol on murine thymocyte proliferation, the mechanism which accounts for the immunosuppressive effect of ethanol on the thymocyte proliferation has not been elucidated. Thus, a mouse model was used to determine (1) whether there is a similarity in the effect of ethanol exposure in vitro and in vivo on the proliferative response of thymocytes to phytohemagglutinin (PHA), (2) whether ethanol exposure affects the responsiveness of thymocytes to exogenous interleukin (IL)-1 and IL-2, and (3) whether ethanol affects IL-1 production by peritoneal macrophages. We found that the proliferative response of thymocytes from mice fed on an ethanol-containing diet was significantly inhibited (P < 0.05) compared to that in mice fed on maltose or standard diets. We also observed that low concentrations of ethanol (12.5 mM) appeared to enhance the mitogenic response of thymocytes to PHA, but the response was not significantly greater than that of controls (P > 0.05). Ethanol at higher concentrations (25-100 mM) significantly suppressed the mitogenic response of thymocytes to PHA (P < 0.05) in a dose-dependent manner. Our data also revealed that (1) ethanol did not significantly suppress IL-1 secretion by adherent macrophages stimulated by LPS, and (2) the addition of exogenous IL-1 was insufficient to restore full responsiveness in thymocytes from ethanol-fed mice. Taken together, these results suggest that the suppressive effect of ethanol on thymocyte proliferation is not mediated by insufficient IL-1. Finally, we present novel evidence that addition of exogenous IL-2 completely restores the impaired proliferative response of thymocytes from ethanol-fed mice to control levels. In summary, our results demonstrate that ethanol inhibits thymocyte proliferation in response to PHA, and that the inhibition is not due to insufficient IL-1. We also report that addition of exogenous IL-2 is sufficient to restore full proliferative capacity to thymocytes from ethanol-fed mice.

Animals↗
PubMed1996

Circulating levels of cytokines and their endogenous modulators in patients with mild to severe congestive heart failure due to coronary artery disease or hypertension.

OBJECTIVES: This study sought to determine the circulating levels of cytokines and their respective endogenous modulators in patients with congestive heart failure of variable severity. BACKGROUND: Activation of immune elements localized in the heart or periphery, or both, may promote release of cytokines in patients with congestive heart failure. Although an increased circulating level of tumor necrosis factor-alpha (TNF-alpha) and its soluble receptor type II (sTNF-RII) is well documented, less is known about other cytokines (i.e., interleukin-1-beta [IL-1-beta], interleukin-6 [IL-6] and interleukin-2 [IL-2] and their soluble receptor/receptor antagonists). METHODS: Circulating levels of TNF-alpha and sTNF-RII, IL-1-beta, IL-1 receptor antagonist (IL-1-Ra), IL-6, IL-6 soluble receptor (IL-6-sR), IL-2 and IL-2 soluble receptor-alpha were measured using enzyme-linked immunosorbent assay kits (Quantikine, R&D Systems) in 80 patients with congestive heart failure due to coronary artery disease or hypertension. The severity of their symptoms, which ranged from New York Heart Association functional class I to IV, was confirmed by measurement of peak oxygen consumption. RESULTS: The percentage of patients with elevated levels of cytokines and their corresponding soluble receptor/receptor antagonists significantly increased with functional class. For TNF-alpha and IL-1-beta, the percentage of patients with elevated levels of soluble receptor/receptor antagonists was higher than that of patients with elevated levels of the cytokine itself. For IL-6, the percentage of patients with elevated levels of IL-6-sR tended to be lower than that of patients with elevated levels of IL-6. All but two patients had undetectable levels of IL-2, and all but seven had levels of IL-2-sR within a normal range. CONCLUSIONS: In patients with congestive heart failure, circulating levels of cytokines increased with the severity of symptoms. In these patients, circulating levels of sTNF-RII and IL-1-Ra are more sensitive markers of immune activation than are circulating levels of TNF-alpha and IL-1-beta, respectively. Levels of IL-2 and IL-2-sR are not elevated when congestive heart failure is due to coronary artery disease or hypertension.

Aged↗
PubMed1996

Molecular characterization of the V regions of four IgE antibodies specific for trichosanthin.

We report here the cDNA cloning and variable region nucleic acid sequences of the heavy and the light chains of four monoclonal IgE and one monoclonal IgG1 antibodies against trichosanthin (TCS), all of which recognized a similar or related antigenic determinant. Sequence analysis revealed that the VH regions of the four IgE antibodies use different V gene segments from the 7183, 36-60 and J558 families. The DH genes varied extensively in nucleotide sequence and length, with D segments DSP2, DFL16 and DQ52 being used with equal frequency. All JH gene segments except JH1 were present in the epsilon transcripts. In contrast, there appeared to be restricted L-chain utilization. All four L-chain V genes cloned belonged to the V kappa 21 family and a bias in the use of J kappa 1 gene was also observed. The VL sequences of the anti-TCS monoclonal antibodies showed much less diversity than the VH sequences. We propose that the L-chain rather than H-chain may play a more significant role in specific binding with allergenic determinant on TCS.

Amino Acid Sequence↗
PubMed1996

Rat intestinal and hepatic ferritin subunit expression during development and after dietary iron feeding.

Ferritin consists of 24 heavy (H) and light (L) subunits in varying proportions in different tissues and plays a significant role in iron metabolism. We studied rat ferritin subunit expression in the duodenum and liver during early life, when a cycle of iron depletion and repletion occurs. In both tissues, ferritin contents decreased to low levels from day 3 to day 12. The ferritin on day 3 had an H/L mRNA ration of 0.9 and an H/L subunit ratio of 0.6. The decrease of tissue ferritin levels, but not mRNA, on day 12 suggests translational repression consistent with iron depletion. In the duodenum, a twofold increase in both H and mRNA and subunit protein occurred on day 18. The subsequent increase of H mRNA was accompanied by a 50% decrease in L mRNA, resulting in the increase of H/L mRNA and subunit ratios to 7.9 and 9, respectively, by day 32. In contrast, liver H/L mRNA and subunit ratios were similar throughout development. The possibility that dietary iron regulates duodenal ferritin subunit expression was investigated. When day 12 rats were fed 6 ml of a milk formula containing 56 microgram/ml iron for 18 h, dietary iron increased the duodenal levels of L mRNA but not H mRNA. In contrast, hepatic H and L mRNA levels did not change. Dietary iron promoted greater increases in ferritin protein than mRNA in both tissues. Thus a shift from L-rich to H-rich ferritin isoforms occurs in the duodenum but not in the liver during neonatal development. This change is regulated at the pretranslational level and is independent of dietary iron.

Aging↗
PubMed1995

Caesarean section in a patient with protein S deficiency.

Protein S is a nonenzymatic and vitamin K-dependent cofactor of activated protein C. Without protein S, the anticoagulant function of protein C is almost depleted and thrombotic events occur. We report a parturient with hereditary protein S deficiency in whom the risk of thromboembolism was further complicated by pregnancy and who required emergency Caesarean section for fetal distress.

Adult↗
PubMed1995

Dissociated changes of frontal and parietal somatosensory evoked potentials in sleep.

We studied the changes of frontal and parietal somatosensory evoked potentials (SEPs) in the awake state versus different stages of sleep in 10 normal adult subjects. Frontal and parietal SEP components were affected differentially as sleep stages progressed. In general, the amplitudes of frontal components, notably P22, were increased in sleep, whereas the amplitudes of parietal components were decreased in sleep. A sensitive waveform change from the awake state to sleep was present in the frontal response, where a subtle notched negativity, termed "N40," was present only in the awake state and quickly dissipated in all stages of sleep, including stage 1. The amplitude changes from the awake state to stage 3/4 sleep were neither linear nor parallel among SEP components. The most discordant changes occurred in stage 3/4. The amplitudes for the frontal N18-P22-N30 complex and parietal N20-P26-N32 complex increased from stage 2 to stage 3/4, while those for frontal N30-fP40 and parietal N32-pP40 decreased. In contrast to these divergent amplitude changes, the latencies of all components except P14 and frontal N18 showed progressive prolongation from the awake state to slow-wave sleep. The SEP waveforms and latencies in REM sleep approximated those in the awake state, although amplitudes for frontal peaks still remained slightly higher and amplitudes for parietal peaks slightly lower. We postulate that interactions of excitatory and inhibitory phenomena are responsible for the component-dependent and sleep-stage-dependent amplitude enhancement or depression in sleep.

Adult↗