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Biomedical subjects

J Gan

Publications and source records attributed to J Gan.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Effects of microwave baking on the immunological cells in primary lymphedema patients].

OBJECTIVE: To elucidate the effects of microwave on the immunological cells in primary lymphedema. METHODS: The immunological cells including lymphocytes in the affected limb skin and peripheral blood of 10 patients with primary lower limb lymphedema were analysed using ABC and APAAP immunohistochemical methods before and after microwave baking and bandaging treatment. RESULTS: It is demonstrated that in the peripheral blood of the patients there was an increase of CD8+ T lymphocytes as well as a decrease of CD4+ T lymphocytes and the ratio of CD4/CD8. It was found that there was significant perivascular infiltration of mononuclear cells (most were monocytes and macrophages) in the skin of the affected limb. CONCLUSION: Microwave modulates the systemic immunological imbalance by its heating and complex biological effects on primary lymphedema patients through reversing the ratio of CD4/CD8 to normal level by increasing CD4+ T lymphocytes and decreasing CD8+ T lymphocytes. It can also decrease the perivascular T-lymphocyte infiltration of the affected dermis and enhance the phagocytic capabilities by promoting the proteolytic activities of macrophages, finally resulting in edema resolution.

Adolescent↗
PubMed1999

Effects of microwave heating on systemic and local infiltrating lymphocytes in patients with chronic limb lymphedema.

OBJECTIVES: To observe the characteristics of lymphocyte phenotypes in systemic and local skin and to evaluate the effects of microwave heating and bandaging treatment on chronic limb lymphedema. METHODS: Totally 27 patients with lymphedema and 10 normal subjects were examined with alkaline phosphatase-anti-alkaline phosphatase (APAAP) and avidin-biotin-peroxidase (ABC) immunohistochemistry for the observation of systemic lymphocyte phenotypes and inflammatory cell infiltration of skin tissues. RESULTS: In the peripheral blood of patients with chronic limb lymphedema, the number of CD4 T lymphocytes and the ratio of CD4/CD8 decreased, while the number of CD8 T lymphocytes increased. Obvious dermal perivascular infiltration of T lymphocytes was also observed. After two courses of microwave heating and bandaging treatment, the number of CD4 T lymphocytes augmented and the decreased CD4/CD8 ratio returned to normal, and the number of CD8 T lymphocytes reduced. The perivascular T lymphocyte infiltration in the dermis resolved and the number of macrophages elevated. CONCLUSION: Microwave heating and bandaging treatment can regulate the imbalance of systemic and local immunity in patients with chronic lymphedema.

Adolescent↗
PubMed1998

Tolerance induction by "megadose" hematopoietic transplants: donor-type human CD34 stem cells induce potent specific reduction of host anti-donor cytotoxic T lymphocyte precursors in mixed lymphocyte culture.

BACKGROUND: Recently, the use of megadoses of CD34+ hematopoietic progenitors has been reported to abrogate resistance to engraftment, thus overcoming major histocompatibility barriers in bone marrow transplantation in leukemia patients. METHODS: The ability of human CD34+ cells to possess potent tolerizing activity was studied by limiting dilution analysis of cytotoxic T lymphocyte (CTL) precursors (CTL-p) in human peripheral blood lymphocytes after addition of purified CD34+ cells. RESULTS: The addition of purified human CD34+ cells to primary mixed lymphocyte culture led to a marked reduction of antiallogeneic CTL-p frequency against stimulator cells of the same origin, compared with the response against cells of third-party origin. The CD34+ cells caused a marked inhibition of the CTL activity, when added at an equal number with the responder T cells, and they were still present after the mixed lymphocyte culture, which suggests that no significant killing of CD34+ cells had occurred. The tolerizing activity is abrogated by irradiation and requires cell contact. This pattern of tolerization most closely resembles what has been ascribed to veto cells in other systems. Phenotypic analysis of the purified CD34+ cells showed that they express MHC class I and class II antigens, but do not express costimulatory molecules of the B7 family. CONCLUSIONS: It is possible, that CD34+ cells in the megadose transplants-perhaps by their inability to provide costimulatory molecules-are actively reducing the frequency of CTL-p directed against their antigens, and thereby help to overcome allogeneic rejection, and enhance their own engraftment.

Antigens, CD34↗
PubMed1998

Volatility, Adsorption, and Degradation of Propargyl Bromide as a Soil Fumigant.

During the 1960s, propargyl bromide (3-bromopropyne, C(3)H(3)Br, or 3BP) was used in a soil fumigant Trizone, a combination of chloropicrin, methyl bromide, and propargyl bromide. Since a great deal of attention is being placed on finding replacements for methyl bromide (CH(3)Br, MeBr) in soil fumigation, there is a revived interest in developing propargyl bromide as an alternative fumigant. However, at present, no information exists for assessing its behavior and safety in the environment. In this study, several important parameters needed to determine its environmental fate are obtained. These include basic parameters such as solubility, saturated vapor density, the Henry's law constant, adsorption, and degradation. These parameters are compared to MeBr and 1,3-dichloropropene (1,3-D), a methyl bromide alternative. At 25 degrees C, the Henry's law constant, K(H), for 3-bromopropyne is 0.046, which is smaller than that for MeBr and similar in magnitude to that for 1,3-D. In water at 25 degrees C, the solubility is approximately 1.5% and 3BP slowly degrades with a hydrolysis half-life of 47 days. In soil, the degradation half-life ranged from 1.2 to 5 days, depending on the soil type. Under typical agricultural conditions, 3BP will move readily in soils, a desirable characteristic for fumigants, but, due to its short soil degradation time, should not pose a serious environmental risk.

Journal Article↗
PubMed1998

Effects of third intracerebroventricular injections of corticotropin-releasing factor (CRF) on ethanol drinking and food intake.

Corticotropin releasing factor (CRF), a neuropeptide secreted by hypothalamic and extrahypothalamic neurons, is thought to mediate stress-related behaviors. The tension reduction hypothesis suggests that ethanol drinking reduces stress; that drinking is reinforced by this reduced stress; and that the probability of drinking therefore subsequently increases. CRF also decrease food intake, and might decrease ethanol drinking similarly. We addressed these hypotheses directly by assessing the effects of intracerebroventricular (i.c.v.) CRF upon ethanol drinking (1 h/day). Rats were provided drinking tubes containing ethanol solutions that were gradually incremented in concentration (from 2% to 8% w/v, over 38 days). Ethanol intakes remained stable, ranging from 0.4 to 0.5 g/kg per hour on average, and a two-bottle choice test revealed that ethanol was preferred reliably to water. Third-i.c.v. cannulae were surgically implanted and CRF or vehicle was acutely injected immediately prior to the sessions. CRF dose-dependently reduced ethanol intake by 31% (0.5 microg) and 64% (5.0 microg), and reduced 24-h food by 9% and 21%, respectively, but did not alter body weights. I.c.v. CRF reduced ethanol drinking despite any acute stress-like effects that may have been present. Hence, these data are inconsistent with the tension reduction hypothesis. On the other hand, our results support the concept that food intake and ethanol drinking may be mediated by similar mechanisms.

Alcohol Drinking↗
PubMed1998

Feasibility, toxicity, and biologic response of interleukin-2 after consolidation chemotherapy for acute myelogenous leukemia: a report from the Children's Cancer Group.

PURPOSE: Although remission can be achieved in 80% of children with acute myelogenous leukemia (AML), many patients experience relapse. Because interleukin-2 (IL-2) can induce remission in patients with overt evidence of AML, we hypothesized that IL-2 given to patients in first remission after intensive consolidation chemotherapy might prevent relapse. This study sought to determine whether such an approach was feasible. PATIENTS AND METHODS: Twenty-one patients in complete remission received IL-2 after completion of treatment on Children's Cancer Group (CCG) protocol 2941. Recombinant IL-2 9 x 10(6) IU/m2 daily by continuous intravenous infusion (c.i.v.) was given for 4 days. After 4 days rest, IL-2 1.6 x 10(6) IU/m2 daily c.i.v. was resumed for 10 days. We monitored patients for toxicity and measured absolute lymphocyte count, the absolute count of cells that express CD56 and CD3 antigen, and soluble IL-2 receptor alpha-chain (sIL-2R alpha) levels before the start of IL-2 and after completion of each of the two courses of IL-2. RESULTS: Observed toxicities included fever (57%), vascular leak (48%), hypotension (38%), tachycardia (14%), rash (29%), septicemia (5%), thrombocytopenia (29%), elevated transaminase (14%), electrolyte disturbance (29%), and hyperglycemia (10%). No patient required cardiac pressors or transfer to an intensive care unit. All patients studied developed an increase in lymphocyte count, CD56 count, CD3 count, and sIL-2R alpha levels after treatment with IL-2. CONCLUSION: This schedule of IL-2 was reasonably well tolerated by children with AML in first remission. After treatment, increased levels of sIL-2R alpha were observed. CCG is conducting a randomized prospective trial to assess the efficacy of IL-2 to prevent the relapse of AML (CCG-2961).

Adolescent↗
PubMed1998

[Relationship between expression of tumor suppressor protein p21 and p53 and cell proliferation in the gastric carcinoma].

To study the relationship between the expressions of tumor supressor protein p21 and p53 and malignant growth of gastric carcinoma, 88 paraffin embedded specimens of gastric carcinoma and gastric ulcer were examined with immunohistochemical method. We found that the expression rate of mutated protein p53 in the gastric carcinoma was about 40% and the expression rate of p21 protein in gastric mucous carcinoma, undifferentiated carcinoma, poorly differentiated carcinoma was obviously low. The expression of PCNA in gastric adenoid cancer was very high. The results suggest that the low expression of p21 proteins and mutation of p53 proteins in gastric cancer cells play a certain role in the morbidity of gastric carcinoma, but its involvement in the malignant growth of gastric carcinoma cells is not obvious.

Adenocarcinoma↗
PubMed1998

Enhancement of gamma-aminobutyric acidA receptor activity by alpha-chloralose.

alpha-Chloralose is widely used as an anesthetic in the laboratory due to its minimal effects on autonomic and cardiovascular systems, yet little is known about its mechanism of action. We examined the effects of alpha-chloralose on gamma-aminobutyric acid type A (GABAA) receptor activity because recent studies have shown that several classes of general anesthetics modulate the function of this receptor. GABAA receptor activity was assayed by measuring the GABA-induced current in Xenopus oocytes expressed with human GABAA receptor alpha-1, beta-1 and gamma-2L subunits. alpha-Chloralose produced a concentration-dependent potentiation of the GABA-induced current with an EC50 value of 49 microM and a maximal effect of 239% of control. Membrane current was not affected by alpha-chloralose in the absence of GABA. alpha-Chloralose (100 microM) increased the affinity for GABA 5-fold and produced a small (17%) increase in the efficacy of GABA. Measurement of the reversal potentials for the alpha-chloralose response suggested that the effect is mediated through increased Cl- conductance. Studies of alpha-chloralose interactions with other allosteric modulators determined that alpha-chloralose binds to a site on the GABAA receptor complex distinct from the benzodiazepine, neurosteroid and barbiturate sites. Chloral hydrate, trichloroethanol and urethane also augmented GABA-induced currents. alpha-Chloralose had no effect on the hydroxytryptamine-induced currents in oocytes expressed with the 5-hydroxytryptamine3 receptor. These data extend the number of classes of anesthetics that allosterically modulate GABAA receptor activity and indicate that GABAA receptors may be a common site of action for diverse classes of general anesthetics.

Anesthetics, Intravenous↗
PubMed1997

A phase I/IB trial of murine monoclonal anti-GD2 antibody 14.G2a plus interleukin-2 in children with refractory neuroblastoma: a report of the Children's Cancer Group.

BACKGROUND: The murine monoclonal antibody (MoAb) 14.G2a recognizes GD2, a disialoganglioside expressed in tumors of neuroectodermal origin, and facilitates antibody dependent cellular cytotoxicity (ADCC) in vitro. When given in vivo, interleukin-2 (IL-2) can increase ADCC by enhancing the activity and number of circulating lymphocytes. METHODS: Thirty-three pediatric patients with GD2 positive malignancies, ranging in age from 2 to 17 years (median, 9.9 years), received IL-2 and 14.G2a in this Phase I/IB study of the Children's Cancer Group (CCG) and were monitored for toxicities and response to therapy. Seven of these patients also received granulocyte-macrophage-colony stimulating factor. RESULTS: The maximum tolerated dose (MTD) of 14.G2a with IL-2 was 15 mg/m2/day. The most prevalent Grade 3-4 toxicities were generalized pain (n = 14 [42%]) and fever without documented infection (n = 17 [52%]). IL-2 was thought to be the causative agent in most cases of fever. Toxicities attributed to 14.G2a included pain, allergic or anaphylactic reactions, and rash. Human antimouse antibodies were demonstrated in 9 of 21 evaluated patients. One patient with neuroblastoma had a partial response, and one patient with osteosarcoma had a complete response. Immunocytology demonstrated that the number of neuroblastoma cells in bone marrow decreased in three patients. CONCLUSIONS: The murine MoAb 14.G2a was well tolerated at the MTD and appeared to have some antitumor activity. Further development of this approach will involve additional engineered forms of the antibody as well as testing in the adjuvant and minimal residual disease setting.

Adjuvants, Immunologic↗
PubMed1997

Phase I/IB study of immunization with autologous tumor cells transfected with the GM-CSF gene by particle-mediated transfer in patients with melanoma or sarcoma.

The objective of this Phase I study is to assess the acute and long-term toxicities of intradermal vaccination of cancer patients with lethally-irradiated tumor cells that have been transfected by particle-mediated gene transfer (PMGT) with gold particles coated with human granulocyte-macrophage colony stimulating factor (GM-CSF) DNA in a plasmid expression vector. The GM-CSF DNA-coated gold particles are delivered to tumor cells using helium pressure with a hand held gene delivery device. Preclinical studies have demonstrated that vaccination of mice with irradiated, GM-CSF-transfected melanoma cells provided protection from subsequent challenges with non-irradiated, non-transfected tumor cells. Ongoing human tumor immunotherapy studies use patients' melanoma or renal carcinoma cells transfected with a retroviral vector containing GM-CSF cDNA as a vaccine to elicit anti-tumor immune responses. PMGT transfection, unlike retroviral transfection, does not require tumor cells to proliferate in vitro to undergo gene transfer. Instead, tumor tissue can be dissociated into small tissue clumps or cell aggregates and then immediately transfected using the gene gun. PMGT physically inserts the DNA without the need for cell surface interaction with viral components or exposure of the patient to viral antigens. As described in this protocol, fresh human sarcoma and melanoma specimens can be transfected with the GM-CSF DNA-coated gold particles with subsequent production of biologically active GM-CSF protein. In this study tumor tissue will be obtained from patients with melanoma or sarcoma. Tumor tissue will be dissociated, irradiated, and transfected with GM-CSF DNA by PMGT. In this ascending dosage study, two dose levels of GM-CSF DNA will be studied in 2 groups of 6 patients each. Patients will receive two intradermal injections of the irradiated, transfected tumor in a single extremity. On days 3 and 14 post-vaccination, patients will undergo surgical excision of the vaccination sites to assess GM-CSF production and infiltration of immune effector cells. On Day 25, patients will undergo DTH testing with intradermal injection in their opposite extremity of 5 x 10(6) irradiated non-transfected autologous tumor cells cryopreserved at the time of vaccine preparation. This injection site will be assessed on day 28 post-vaccination and surgical excision of the DTH testing site will be performed on day 28 if a positive reaction is noted. The patients will be observed for local and systemic toxicity on days 2, 3, 5, 8, 14, 25, and 28 after the vaccination. Restaging of the patients' disease and long term toxicity evaluation will be performed at 3, 6, and 12 months and then yearly.

Animals↗
PubMed1997

Alteration of the CD34+ Tf-1 beta cell line profile in response to long-term exposure to IL-15.

Interleukin 15 (IL-15) is a cytokine with many functional characteristics that are similar to IL-2. Most of the functional activities that IL-2 and IL-15 support have been evaluated in short-term assays. It was our intention, then, to determine the long-term effects of IL-15 in comparison to IL-2. These studies were performed using the growth factor-dependent myelomonocytic cell line, Tf-1, which has been well characterized with regard to morphology, CD marker expression, responses to certain growth factors and cytokines (GM-CSF, IL-4, erythropoietin), and can differentiate through the myeloid and erythroid lineages. In order to study IL-2 and IL-15 responses, Tf-1 cells were retrovirally infected with the IL-2R beta chain gene as a means to confer IL-2 responsiveness to this cell type. The results of this study demonstrate that retroviral infection of Tf-1 successfully generated a stable IL-2 responsive cell line, Tf-1 beta, without interfering with the original characteristics of the Tf-1 cell. Tf-1 beta cells respond functionally to both IL-2 and IL-15. When Tf-1 beta cells are grown for 8 weeks in IL-2 (Tf-1 beta 2), rather than GM-CSF, the original morphology, CD marker expression, esterase activity and proliferative response is unaltered in comparison to that of the original Tf-1 beta line maintained in GM-CSF. However, long-term growth of Tf-1 beta in IL-15 (Tf-1 beta 15) results in morphological alterations, downregulation of CD33, CD38, and HLA-DR, and a decreased response to IL-15 in comparison to Tf-1 beta 2. These studies support the concept that retroviral infection, even when it confers new functions upon a cell, does not necessarily alter all other functions, as assessed by evaluation of its phenotypic profile. Furthermore, the production of the Tf-1 beta 2 and Tf-1 beta 15 sublines demonstrates that IL-2 and IL-15 can support long-term cell growth. However, this long-term growth in IL-15 leads to subtle alterations in the cell profile that are not seen with IL-2, suggesting that distinctions in IL-2 and IL-15 function do exist. Further study of the Tf-1 beta 15 cell line will be useful to clarify these functional distinctions between IL-2 and IL-15.

ADP-ribosyl Cyclase↗
PubMed1997

The GABAA receptor alpha 6 subunit gene (Gabra6) is tightly linked to the alpha 1-gamma 2 subunit cluster on mouse chromosome 11.

We have established that the GABAA receptor alpha 6 (Gabra6) and alpha 1 (Gabra 1) subunit genes are tightly linked on mouse chromosome 11 by analysing the strain distribution patterns of RFLPs for the two genes and microsatellite markers flanking these genes in 26 BXD recombinant inbred strains. These results further demonstrate clustering of the GABAA receptor subunit genes on mouse chromosomes and the synteny for these clusters between the mouse and human genomes.

Animals↗
PubMed1997

Depolarization and activation of dihydropyridine-sensitive Ca2+ channels stimulate inositol phosphate accumulation in photoreceptor-enriched chick retinal cell cultures.

Elevated concentrations of extracellular K+ increased inositol phosphate accumulation in primary cultures of chick retinal photoreceptors and multipolar neurons. K+-evoked stimulation of inositol phosphate accumulation was greater in photoreceptor-enriched cell cultures than in cultures where multipolar neurons were the predominant cell type. Destroying multipolar neurons, but not photoreceptors, with kainic acid and N-methyl-D-aspartate did not reduce the K+-evoked stimulation of inositol phosphate accumulation. Both of these observations indicate that the observed effects occur in photoreceptor cells. The K+-evoked stimulation of inositol phosphate accumulation was blocked by omitting Ca2+ from the incubation medium or by adding the dihydropyridine-sensitive Ca2+-channel antagonists, nitrendipine and nifedipine. Bay K 8644, a dihydropyridine agonist, stimulated inositol phosphate accumulation and enhanced the effect of K+. omega-Conotoxin GVIA, an inhibitor of N-type Ca2+ channels, had no significant effect on K+-stimulated inositol phosphate accumulation. Pretreatment with pertussis toxin neither blocked K+-evoked inositol phosphate accumulation nor altered the inhibitory effect of nifedipine. K+-evoked inositol phosphate accumulation appears to reflect activation of phosphatidylinositol-specific phospholipase C, as it is inhibited by U-73122. These results indicate that Ca2+ influx through voltage-gated, dihydropyridine-sensitive channels activates phospholipase C in photoreceptor inner segments and/or synaptic terminals.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1997

[Study on the separation and determination of phthalates in plants].

A convenient and efficient method for analysis of phthalate esters (PEs) in plants was developed. PEs in plants were extracted with dichloromethane by ultrasonication, separated by chromatography with a column chromatography packed with 10-40microm sillica and then determined by HPLC on a 250mm x 4.6mm i.d. ODS column using MeOH/H2O (88:12) as mobile phase and UV detection at 228nm. The minimum detectable limits for diethyl phthalate (DEP) and diethylhexyl phthalate (DEHP) were 47pg and 85pg respectively. The overall recoveries of PEs were found to be 85%-101%. The method has been satisfactorily applied to the determination of plant samples.

Chromatography, High Pressure Liquid↗
PubMed1997

[Design and application of vacuum manifold for solid phase extraction].

Solid phase extraction (SPE) is now a common method for sample pretreatment. SPE vacuum manifold is a key instrument when SPE is used for sample pretreatment. It was developed by National Chromatographic R. & A. Center. Being connected with a vacuum pump, it can deal with 12 samples simultaneously. The manifold has a unique rotatable cover and can be conveniently rotated when switching between any two steps of SPE. An application of this SPE vacuum manifold in measuring bile acids in human serum was given.

Bile Acids and Salts↗
PubMed1997

Phase IB trial of chimeric antidisialoganglioside antibody plus interleukin 2 for melanoma patients.

We conducted a Phase IB trial of antidisialoganglioside chimeric 14. 18 (ch14.18) antibody and interleukin 2 (IL-2) to determine the maximal tolerated dose (MTD), immunological effects, antitumor effects, and toxicity of this treatment combination. Twenty-four melanoma patients received immunotherapy with ch14.18 antibody and a continuous infusion of Roche IL-2 (1.5 x 10(6) units/m2/day) given 4 days/week for 3 weeks. The ch14.18 antibody (dose level, 2-10 mg/m2/day) was scheduled to be given for 5 days, before, during, or following initial systemic IL-2 treatment. The ch14.18 MTD was 7.5 mg/m2/day, and 15 patients were treated with the ch14.18 MTD. Immunological effects included the induction of lymphokine-activated killer activity and antibody-dependent cellular cytotoxicity by peripheral blood mononuclear cells. In addition, serum samples obtained following ch14.18 infusions were able to facilitate in vitro antibody-dependent cellular cytotoxicity. Antitumor activity included one complete response, one partial response, eight patients with stable disease, and one patient with >50% decrease of hepatic metastases in the face of recurrence of a s.c. lesion. Dose-limiting toxicities were a severe allergic reaction and weakness, pericardial effusion, and decreased performance status. Most patients treated at the MTD had abdominal, chest, or extremity pain requiring i.v. morphine. One patient had an objective peripheral neuropathy. This IL-2 and ch14.18 treatment combination induces immune activation in all patients and antitumor activity in some melanoma patients. We are attempting to enhance this treatment approach by addition of the anti-GD3 R24 antibody to this IL-2 and ch14.18 regimen.

Adult↗