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Biomedical subjects

Q Chang

Publications and source records attributed to Q Chang.

85 records · Page 5Linked to original sources
PubMed1995

Maturation of mobilized peripheral blood progenitor cells: preclinical and phase I clinical studies.

The use of mobilized peripheral blood progenitor cells (PBPC) after high-dose chemotherapy has markedly decreased the period of severe neutropenia. In an attempt to further decrease the duration of neutropenia, the potential of PBPC to mature during in vitro culture was assessed, with special attention being paid to culture medium, growth factors, and cell concentration. Concentrations of 10(6) PBPC/mL resulted in better recovery than 10(7)/mL as far as total cells, CFU-GM, and granulocytes were concerned. The combination of IL-3 + GM-CSF+G-CSF appeared to be better than any of these growth factors alone. Simple media, such as Medium 199, gave poorer cell recovery than more complex media, such as IMDM. With 10(6)/mL nonenriched PBPC in IMDM with IL-3/GM-CSF/G-CSF, on day 15 CFU-GM reached 450% of the initial level. At that point, granulocytes had increased 15-fold. A small phase I study was performed to assess the toxicity of infusing 1000-2000 mL of PBPC cultured for 3 days at 3-10 x 10(6)/mL with IL-3/GM-CSF/G-CSF in LifeCell bags. Although no clear decrease in the duration of neutropenia was observed, the infusions were uncomplicated in 5 of the 6 patients and had minor side effects in the sixth patient. These data suggest that in vitro differentiation of nonenriched PBPC is possible. However, to develop a clinically applicable method, several logistical problems will have to be overcome.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Selective T cell depletion with CD8-conjugated magnetic beads in the prevention of graft-versus-host disease after allogeneic bone marrow transplantation.

The effects of a new immunomagnetic method of selectively depleting CD8+ lymphocytes from donor bone marrow were studied in 29 patients undergoing transplantation from HLA-identical sibling (n = 20) or alternative (n = 9) donors. The direct immunomagnetic depletion method consistently removed > 95% of CD8+ cells and the non-specific loss of other cell subsets was only about 15%. Recovery of CFU-GM and BFU-e was on average > 100%. The final graft contained 0.9 +/- 0.6 x 10(8)/kg nucleated cells and 1.4 +/- 2.7 x 10(5)/kg CD8+ cells. Patients also received cyclosporine starting day -1. Engraftment occurred in 28 patients (97%), including three patients who received a non-TBI conditioning regimen. One patient receiving an unrelated transplant failed to engraft. Median time to ANC > 500 x 10(6)/L was 17 (12-23) days. Four of 20 patients receiving grafts from HLA-identical siblings (20%) developed acute GVHD grade > or = II. However, five of eight patients with grafts from alternative donors (63%) had grade > or = II GVHD. Nearly all patients developed fever around day 7, accompanied by fluid overload, mild skin rash and shortness of breath. This syndrome necessitated treatment with steroids. Immunomagnetic CD8 depletion is a simple and reproducible method of selective T cell depletion. In combination with cyclosporine it appears to be effective in the prevention of severe acute GVHD in HLA-identical sibling transplants, but not in transplants from less perfectly matched donors.

Adult↗
PubMed1995

Stress triggers different pathophysiological mechanisms in younger and older cardiomyopathic hamsters.

OBJECTIVES: Because cardiomyopathic hamsters (CMHs) in the lesion-forming period of their disease are more susceptible to the lethal effects of stress than older CMHs, we tested the hypothesis that different pathophysiological effects of stress may occur: coronary vasospasm in younger CMHs and congestive heart failure in older ones. METHODS: CMHs aged 2.5 and 6.5 months were stressed with 2 h supine cold immobilization for 5 consecutive days. Three, 5 and 7 days after stress, the hearts were excised and perfused using a modified Langendorff system. Maximum +/- dP/dt, developed pressure, ventricular relaxation time (Tau) and coronary vascular resistance (CVR) were recorded and CVR was also measured following coronary infusion of arginine vasopressin (AVP). RESULTS: Stress produced ventricular dysfunction (decreased maximum +/- dP/dt, developed pressure, and increased Tau) in older CMHs (P < 0.05) but not in younger CMHs. Baseline CVR in younger CMHs was significantly higher than in older CMHs (P < 0.01) and AVP infusion produced a bigger increase in CVR in younger stressed CMHs than in either younger nonstressed or older stressed CMHs (P < 0.05). CONCLUSION: The younger CMH heart exhibits greater resting vascular tone and stress produces coronary vasoconstriction that is consistent with coronary spasm. In contrast, the older CMH experiences a decrease in cardiac function which remains 7 days after stress and indicates an exacerbation of CHF from the mild form existing prior to stress. The lethal effects of stress may occur because of the activation of different pathological processes in younger and older CMHs.

Age Factors↗
PubMed1994

Fourier transform infrared spectra studies of protein in reverse micelles: effect of AOT/isooctane on the secondary structure of alpha-chymotrypsin.

The amide I region Fourier transform infrared (FTIR) spectra of alpha-chymotrypsin have been studied in deuterium oxide (D2O) solution and also in reverse micellar solution of AOT/isooctane. The Fourier second derivative was applied to all spectra, revealing that the amide I band of alpha-chymotrypsin in D2O and in reverse micellar solution consists of nine components. The band frequencies are assigned to alpha-helix, beta-sheet, random and turn structure. The second derivative spectra of alpha-chymotrypsin have been shifted in the reverse micellar solution of AOT/isooctane in comparison with its spectra in D2O. This shift has also changed the intensity of each band. Through accurate measurement of the band intensities, the relative amount of different structure of alpha-chymotrypsin can be estimated. The comparison of the calculated results obtained in D2O with those obtained in reverse micellar solution provides the possibility to analyze the effect of reverse micellar solution of AOT/isooctane on the secondary structure of alpha-chymotrypsin. The results indicate that the reverse micellar solution has decreased the amount of alpha-helix and beta-sheet structure and increased the amount of random and turn structure in alpha-chymotrypsin. The increase of the amount of random structure might loosen the structure of alpha-chymotrypsin and change the activity of the enzyme.

Amides↗
PubMed1994

Extraction of lysozyme, alpha-chymotrypsin, and pepsin into reverse micelles formed using an anionic surfactant, isooctane, and water.

The extraction of lysozyme, alpha-chymotrypsin, and pepsin from buffered salt solutions into reverse micelles was examined at different pH values and surfactant concentrations. The reverse micelles was formed by mixing aqueous buffer supplemented with KCl and an organic phase of isooctane(2,2,4-trimethylpentane), containing the anionic surfactant, Aerosol O. T. (dioctyl ester of sodium sulfosuccinic acid). The technique of dynamic laser scattering was used to measure the size of reverse micelles which were in equilibrium with the aqueous phase. It was found that the size of the reverse micelles decreased with increasing ionic strength but increased with increasing AOT concentration. In the process of extraction, the reverse micelles might have rearranged themselves to host the protein. The sizes of protein-filled and -unfilled reverse micelles were different, and an open equilibrium could be reached between them. Under the extraction conditions, only a small number of micelles were found to contain protein.

Chymotrypsin↗
PubMed1993

Sudden death. A neurocardiologic phenomenon.

During the last two decades compelling evidence has been provided for the existence of a tight relation between brain activation of unbalanced autonomic function and arrhythmias ending in SCD. Insular and infralimbic cortex exert direct and indirect effects on hypothalamus and other brain stem nuclei in modulating cardiac sympathetic-parasympathetic interactions. Specifically, sympathetic hyperactivity favors the onset of life-threatening cardiac arrhythmias, whereas vagal activation usually exerts relatively protective and antifibrillatory effects. Epileptic activation of cortical brain sites can turn this system on and probably is responsible partially for the increased incidence of unexpected death in this patient population. The role of environmental stress in arrhythmogenesis and SCD is of great importance in the outcome of heart disease.

Animals↗
PubMed1992

Frequency distribution of Echinococcus granulosus in dog populations in the Xinjiang Uygur Autonomous Region, China.

Age-prevalence and age-intensity data of Echinococcus granulosus in dog populations were collected in four counties in the Xinjiang Uygur Autonomous Region, People's Republic of China. The frequency distribution of the parasite per dog was adequately described by the negative binomial model, with parameter k being 0.0571. The mathematical model of the life cycle of E. granulosus constructed by Roberts et al. (1986--Parasitology, Vol. 92, pages 621-641) was used to estimate the epidemiologic parameters of E. granulosus in Xinjiang. This model showed that the prevailing infection pressure on dogs was 0.4560 infectious insults year-1 and the mean length of an infection was 1.4975 years. The effect of acquired immunity on the prevalence of E. granulosus in dogs was considered to be insignificant.

Age Factors↗
PubMedDate not supplied

Steam-sterilizable, fluorescence lifetime-based sensing film for dissolved carbon dioxide.

An autoclavable sensing film was developed for monitoring dissolved CO2. The sensing film, based on fluorescence resonance energy transfer (FRET), consisted of a fluorescent donor, an acceptor, and a quaternary ammonium hydroxide, which were doped in a two-component silicone film. As no aqueous solution was used in the sensing film matrix, the sensing film was unaffected by osmotic pressure. Fluorescence lifetime was selected as the sensing parameter, and measured in frequency domain using phase fluorometry. Upon exposure to 20% CO2-saturated water, a 43 degrees increase in phase angle was observed at 100 MHz. The process was fully reversible when the sensing film was exposed to nitrogen-saturated water. The estimated response and recovery times for 90% signal change were 1 min (for a step change from 0 to 6.7% CO2-saturated water) and 1.5 min (for a step change from 6.7 to 3.3% CO2-saturated water). When used for on-line monitoring of dissolved CO2 produced by a culture of Escherichia coli, the sensing film showed a similar trend to that obtained from off-line measurements using a wet chemistry analyzer.

Carbon Dioxide↗
PubMedDate not supplied

The role of stressor intensity and underlying vasculopathy in altering coronary reactivity in cardiomyopathic hamsters.

OBJECTIVE: Our previous work showed that stress sensitized the vessels of cardiomyopathic hamsters (CMHs), but only hamsters in the lesion-forming period of their life. We hypothesized that we would find an interaction between stressor intensity and microvascular vulnerability. METHOD: Male CMHs at ages of 1.5, 2.5, and 3.5 months were stressed with supine immobilization for five consecutive days. Stressor intensity was manipulated by immobilizing groups of CMHs at room temperature for 0 minutes, 15 minutes, 30 minutes, 1 hour, or 2 hours. CMHs were anesthetized and sacrificed 5 days after stress, and their hearts were perfused using a modified Langendorff system. Body weight changes and baseline coronary vascular resistance (CVR) were recorded, and CVR was also measured after coronary artery infusion of arginine vasopressin (AVP). RESULTS: Stress produced no effect on coronary vasculature in 1.5-month-old CMHs. In 2.5-month-old CMHs, only the two highest-intensity stressors enhanced coronary reactivity to AVP. In 3.5-month-old CMHs, higher-intensity stressors produced a marginal AVP-induced increase in CVR; but this marginal increase was significantly lower than the increases seen with the two highest-stressor intensities in the 2.5-month-old CMHs. CONCLUSION: The stress-induced coronary hyperreactivity to AVP seen in 2.5-month-old CMHs diminished when microvascular vulnerability was lower in 3.5-month-old CMHs. For 1.5-month-old CMHs, the resting CVR was extremely high, so that the addition of stress produced no further increase. Thus, stressor intensity interacted with microvascular vulnerability to alter the consequences of stress.

Age Factors↗
PubMedDate not supplied

Laparoscopic radical trachelectomy or parametrectomy and pelvic and para-aortic lymphadenectomy for cervical or vaginal stump carcinoma: report of six cases.

The aim of this study was to investigate the feasibility and safety of laparoscopic radical parametrectomy and pelvic and para-aortic lymphadenectomy after previous supracervical or extrafascial hysterectomy. This is a prospective study of six patients with vaginal or cervical stump carcinoma after previous supracervical or extrafascial hysterectomy. The technique of radical parametrectomy with pelvic and para-aortic lymphadenectomy as used for open surgical cases for years was performed laparoscopically. The average operating time was 180 min, the estimated average blood loss was 220 mL, and the duration of hospitalization was 11.8 days. There was no intraoperative or postoperative complication. Laparoscopic radical parametrectomy with pelvic and para-aortic lymphadenectomy for cervical or vaginal stump carcinoma can be successfully and safely accomplished.

Adult↗