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Biomedical subjects

J A Thompson

Publications and source records attributed to J A Thompson.

At least 163 records · Page 9Linked to original sources
PubMed1995

HPLC purification of synthetic oligodeoxyribonucleotides containing base- and backbone-modified sequences.

Applications for a new polymer resin, PolyFlo, are described for both the small-scale and large-scale purification of synthetic oligodeoxyribonucleotides varying in length from 18-41 bases. The unique properties of this innovative resin provide > 95% purified full-length oligodeoxyribonucleotides with greater than 90% yield starting from either crude trityl-on or trityl-off unmodified as well as base (biotin)- or backbone (e.g., phosphorothioate)-modified products. Full biological activity of recovered nucleic acid is retained, and the resin is capable of removing contaminating endotoxins during purification. The resin performance is predictable and reliable. The resin can be regenerated easily and is particularly economic when employed directly in ammonia or with the trityl-off option. PolyFlo meets the requirements of current Good Manufacturing Practices.

Ammonium Hydroxide↗
PubMed1994

Pentoxifylline inhibits integrin-mediated adherence of interleukin-2- activated human peripheral blood lymphocytes to human umbilical vein endothelial cells, matrix components, and cultured tumor cells.

Peripheral blood lymphocytes (PBLs) cultured in the presence of recombinant human interleukin-2 (rhIL-2) develop a natural killer (NK) cell phenotype (CD16+, CD56+, CD3-) and are referred to as lymphokine-activated killer cells (LAK). In developing the LAK phenotype, enhanced adherence to matrix components and endothelial cells have been described. In this report we investigated the functional behavior of adhesion receptors in rhIL-2-activated PBLs by in vitro adhesion assay and by flow cytometry. Compared to PBLs, IL-2-activated PBLs had increased integrin-mediated adherence to: (1) fibronectin (FN), (2) human umbilical vein endothelial (HUVE) cells, and (3) cultured melanoma and pancreatic tumor cell lines. This increase in adherence was mediated by increased surface expression of members of the beta 1 and beta 2 integrin subfamilies, as determined by flow cytometric analysis. No induction of an activation-dependent beta 1 (CD29) epitope was detected. We also investigated the effects of the methylxanthine derivative pentoxifylline (PTX) on PBLs and rhIL-2-activated PBL adhesion. PBLs co-cultivated in the presence of rhIL-2 (1,000 U/mL) and PTX exhibited reduced adherence to FN, HUVE and cultured tumor cell lines. This inhibition by PTX was concentration- and time-dependent. The increased expression of integrins induced by rhIL-2 was only in part inhibited by PTX, suggesting that PTX induced a subpopulation of integrins that are expressed but functionally inactive.

Cell Adhesion↗
PubMed1994

Phase Ib trial of pentoxifylline and ciprofloxacin in patients treated with interleukin-2 and lymphokine-activated killer cell therapy for metastatic renal cell carcinoma.

The dose of interleukin 2 (IL-2) which can be administered to cancer patients is limited largely by a capillary leak syndrome. Pentoxifylline (PTX) is a methylxanthine which reduces IL-2 toxicity in animals. Ciprofloxacin (Cipro) modifies the metabolism of methylxanthines and, when coadministered with PTX, increases levels of PTX and certain of its metabolites. We conducted a phase Ib trial in patients receiving IL-2 and lymphokine-activated killer cell (LAK) cell therapy for metastatic renal cell carcinoma to identify the maximum tolerated dose of PTX which could be coadministered with Cipro in this setting. Eighteen patients received IL-2 (Roche) by continuous infusion at 6 x 10(6) units/m2/day on days 1-5 and underwent leukapheresis on days 7-9. LAK cells were infused on days 12-14. IL-2 was administered at 2 x 10(6) units/m2/day on days 10-20. Cohorts of patients received PTX at 2.5 (n = 3), 3.1 (n = 6), 3.9 (n = 6), and 4.9 (n = 3) mg/kg by 30 min i.v. infusion every 4 h on days 0-5 and 10-20 and Cipro (500 mg p.o. every 12 h) on days 1-5 and 10-20. Toxicity was compared with that observed in 33 historical control patients who received 37 cycles of an identical regimen of IL-2/LAK without PTX/Cipro. PTX at 2.5-3.9 mg/kg and Cipro were well tolerated. The maximum tolerated dose of PTX was 3.9 mg/kg. Dose-limiting emesis (n = 1) and atrial fibrillation (n = 2) occurred at 4.9 mg/kg and were reversible. Two complete, one partial and one minor, responses were observed. Patients treated with 3.9 mg/kg PTX received 95.0% of the planned dose of IL-2 as compared to 72.8% in the control patients (P < 0.025), primarily due to a lower incidence of azotemia and metabolic acidosis in PTX/Cipro recipients than had been seen in the historical control patients. The results of this study demonstrate that PTX/Cipro can be administered to patients receiving IL-2/LAK without apparent loss of therapeutic efficacy. Moreover, PTX/Cipro recipients exhibited less toxicity than historical controls. Therefore, treatment with PTX/Cipro may allow delivery of higher doses of IL-2, which might induce more responses in IL-2-responsive tumors and regression of tumors unresponsive to conventional doses of IL-2.

Adult↗
PubMed1994

Source analysis of generalized spike-wave complexes.

Dipole source analysis was carried out in three adults and four children with 3 c/s generalized spike-wave (SW) discharges and absence seizures. Eighty-seven SW complexes were investigated. When one regional source was used the equivalent location was always near the baso-frontal area close to the midline. It explained on the average 89% of the variance in the adults and 82% in the children. When two regional sources were used and initially constrained for symmetry, the residual variance (RV) was reduced to 7% in the adults and 9% in the children. The sources remained in the frontal areas and were on the average 2 cm from the midline. When the mirror source was freed it remained contralateral in 76% of the complexes but moved ipsilaterally to various locations in the rest. To reduce the RV to between 2 and 3% one or two additional regional sources were required. These were located in the temporal or parietal areas in the adults and occasionally one occipital region in the children. The study showed that widespread and repetitive EEG events, like the generalized SW, can lend themselves to spatio-temporal multiple dipole modeling. More precise anatomic correlates may become possible with an expanded electrode array and the verification of their locations against the patient's MRI scan.

Adolescent↗
PubMed1994

Ratios of serum concentrations of testosterone and progesterone from yearling bulls with small testes.

Thirty crossbred bulls, 12 to 13 mo of age, were used to examine the relationship of testosterone and progesterone concentrations and testosterone: progesterone ratio to measurements of testicular function. Bulls were allotted to 1 of 2 groups based on scrotal circumferences (SC) as follows: the Small SC (n=20) group had scrotal circumference less than 28 cm while the Large SC (n=10) group had scrotal circumference greater than 28 cm. All bulls were administered GnRH (100 mug, im), and blood was obtained immediately prior to injection (t=0), 30 min after injection (t=30) and 2 to 3 h after injection (t=150). Serum was assayed for concentrations of testosterone and progesterone. Semen was evaluated for the percentage of morphologically normal spermatozoa. Testicular parenchyma was sectioned and stained, and 300 cross sections per testis of seminiferous tubules were examined under a light microscope and classified as either active (spermatocytes and spermatids present) or inactive (no spermatocytes or spermatids present). Although progesterone concentrations varied widely (range: 21 pg/ml to 1070 pg/ml), repeated measurements from individual bulls were highly correlated (r(2)=0.74) and did not change significantly (P > 0.1) in response to GnRH treatment. Small SC bulls had a higher percentage of inactive seminiferous tubules (P < 0.001) and a lower percentage morphologically normal spermatozoa (P < 0.001) than Large SC bulls, but no differences in testosterone or progesterone concentrations or in the ratio of testosterone: progesterone were detected. Mean serum testosterone concentration increased (P < 0.0001) by 30 min after GnRH treatment and continued to increase (P < 0.0001) through t=150 but did not differ (p > 0.1) between groups. Normal testosterone secretion in response to GnRH injection suggested that no biochemical lesions in the testosterone production pathway were present in bulls with very small scrotal circumference.

Journal Article↗
PubMed1994

Pregnancy attrition associated with pregnancy testing by rectal palpation.

The objective of this study was to estimate the effect on calving risk of interval from AI date until scheduled date of pregnancy examination. First AI (n = 7105) from 65 dairy herds in the United States and Canada were followed for 294 d to determine whether cows calved. Calving was modeled as a function of the number of days in the interval, herd, season, and breeding at PGF2 alpha-induced estrus by multivariate logistic regression. The main effects of herd and AI following PGF2 alpha-induced estrus were significantly associated with calving rate from first AI. The main effects of interval and season were not significantly associated with calving.

Abortion, Veterinary↗
PubMed1994

Lymphokine-activated killer (LAK) precursor cell activity is present in infused peripheral blood stem cells and in the blood after autologous peripheral blood stem cell transplantation.

Immunotherapy with interleukin-2 (IL-2) early after peripheral blood stem cell transplantation (PBSCT) is being considered as a potential way to eradicate minimal residual disease. The aim of this study was to determine whether lymphocytes which can acquire lymphokine-activated killer (LAK) cell activity are present in PBSC and in the blood of patients after PBSCT. Fresh and cryopreserved G-CSF-mobilized PBSC from eight patients were incubated with IL-2 (1000 U/ml) for 3-6 days and then tested for LAK activity as measured by lysis of the Daudi cell line. LAK activity was present in both fresh and cryopreserved PBSC, with mean lysis of 32% and 36%, respectively, at an effector:target (E:T) ratio of 50:1. To assess the reconstitution of LAK precursor activity after PBSCT, peripheral blood (PB) obtained from eight other patients 15-60 days after PBSCT was similarly tested. LAK activity was detected in PB from every patient (mean lysis of 38% at an E:T ratio of 12.5:1). PB from patients after PBSCT contained a higher percentage of CD8+ cells and CD56+ cells than did PB from 9 normal controls (47.2% vs. 21.4% CD8+ cells, P < 0.005 and 28.6% vs. 8.6% CD56+ cells, P < 0.0005). Moreover, PB from 4 of 5 patients tested after PBSCT exhibited a high percentage of cells expressing p75, the intermediate affinity IL-2R. Thus, precursor cells capable of acquiring IL-2-inducible LAK activity are present in PBSC and are rapidly reconstituted after PBSCT. The findings provide a rationale for testing IL-2 as a way of decreasing relapses after PBSCT.

Adult↗
PubMed1993

Analysis of trimethylsilylperoxy derivatives of thermally labile hydroperoxides by gas chromatography-mass spectrometry.

Qualitative and quantitative determinations of hydroperoxides are of central importance in many areas of biochemical research, but analysis of intact hydroperoxides by capillary gas chromatography-mass spectrometry (GC-MS) generally has not been possible due to the thermal instability of these compounds. It is demonstrated here that structurally diverse hydroperoxides can be converted to trimethylsilyl (TMS) peroxides and analyzed by GC-MS without significant thermal decomposition. The hydroperoxides investigated in this report include cumyl hydroperoxide, 2-phenylethylhydroperoxide, 13-hydroperoxy-octadeca-9,11-dienoic acid, 2,6-di-tert-butyl-4-hydroperoxy-4-methylcyclohexadienone (BHTOOH), and 2,4,6-trimeth-yl-4-hydroperoxycyclohexadienone (TMPOOH). A representative peracid, 3-chloroperoxybenzoic acid, was successfully analyzed as its TMS peroxyester. Chromatographic and mass spectral characteristics of the TMS peroxides and their corresponding TMS ethers were obtained and compared with thermospray HPLC-MS data for underivatized hydroperoxides. The utility of the GC-MS assay for quantitating low levels of hydroperoxides in biological matrices was demonstrated by measuring BHTOOH and TMPOOH formed during the NADPH-dependent oxidation of alkylated phenols by rat liver microsomes. Overall, the results demonstrate that the advantages of GC-MS analysis (i.e., high chromatographic resolution, quantitative precision, high sensitivity, and the acquisition of structural information) can be applied successfully to intact hydroperoxides following trimethylsilylation.

Animals↗
PubMed1993

Metabolic activation of butylated hydroxytoluene by mouse bronchiolar Clara cells.

Metabolism of BHT (2,6-di-tert-butyl-4-methylphenol) is requisite for its pneumotoxic activities. Previous evidence using microsomal preparations from livers and lungs of mice indicated that cytochrome P450-catalyzed hydroxylation of a tertbutyl group to form 6-tert-butyl-2-(hydroxy-tert-butyl)-4-methylphenol (BHTOH) is the first step in the bioactivation of this compound. Subsequent oxidation of BHTOH produces the quinone methide 6-tert-butyl-2-(hydroxy-tert-butyl)-4-methylene-2,5-cyclohexadienone (BHTOH-QM), and this highly reactive electrophile may be directly responsible for the pulmonary effects of BHT. The present study assessed the ability of intact bronchiolar Clara cells isolated from mice, a major site of pulmonary xenobiotic metabolism, to convert BHT to BHTOH-QM. The data demonstrate that BHTOH is, in fact, the principal oxidation product in these cells, and that a substantial portion of this metabolite is oxidized further to the quinone methide. BHTOH was found to be considerably more toxic to Clara cells than BHT, and both toxicity and metabolism were simultaneously depressed by the cytochrome P450 inhibitor SKF 525-A. These results strongly support the hypothesis that BHTOH-QM is the active metabolite that generates acute pneumotoxicity and modulates lung tumor formation.

Animals↗
PubMed1993

Biological and toxicological consequences of quinone methide formation.

Quinone methides are a class of reactive, electrophilic compounds which are capable of alkylating cellular macromolecules. They are formed during xenobiotic biotransformation reactions and are hypothesized to mediate the toxicity of a large number of quinone antitumor drugs as well as several alkylphenols. In addition, oxidation of specific endogenous alkylphenols (e.g. coniferyl alcohol) and alkylcatechols (e.g. N-acetyldopamine, dopa) to quinone methides plays an important role in the synthesis of several complex plant and animal polymers, including lignin, cuticle and melanin. The role of quinone methides in these various processes is reviewed.

Animals↗
PubMed1993

Diet and breed influence the sperm membranes of beef bulls.

Semen was collected from 12 Hereford and 10 Simmental bulls at the conclusion of a 119-day Record of Performance growth trial. Within each breed, the bulls were fed a standard test ration (Diet 1) or an experimental diet consisting entirely of a pelleted concentrate with ground corn cobs as the primary fibre source (Diet 2). Semen was analyzed for motility and morphology while testicular tissue obtained at slaughter the day after semen collection was assessed for seminiferous tubule integrity; none of these parameters varied significantly with breed or diet. The fluidity of head plasma membranes from the spermatozoa was assessed with fluorescence polarization using tPNA. Fluidity decreased over the 160 minute observation period, indicating molecular rearrangments within the head membranes which may reflect sperm changes preceding fertilization. The fluidization displayed a breed-by-diet interaction since membrane fluidity differed significantly between breeds on Diet 1 and between diets for Simmental bulls. Fluidities of some samples were also analyzed with cPNA, and these differed significantly from those obtained with tPNA, indicating the presence of domains in sperm head membranes. Neither diet nor breed affected traditionally measured semen characteristics of Hereford and Simmental bulls, but the membrane dynamics differed between the 2 breeds, and diet affected the sperm membrane dynamics of Simmental bulls.

Journal Article↗
PubMed1993

The effects of pentoxifylline on the generation of human lymphokine-activated killer cell cytotoxicity.

Pentoxifylline (PTX) is a methylated xanthine that has been shown to reduce the toxicity of Interleukin-2 (IL-2) therapy in animal models, possibly by inhibiting secretion of tumor necrosis factor-alpha. However, the use of PTX to reduce IL-2 toxicity in cancer patients would be advantageous only if PTX did not abrogate antitumor effector mechanisms. We therefore tested the effects of PTX on the induction of lymphokine-activated killer (LAK) cell reactivity in human peripheral blood mononuclear cells (PBMCs). LAK precursor and effector activity were defined as lysis of Daudi cells by PBMCs after incubation with IL-2 at 1,000 U/ml (LAKp) or without incubation (LAKe). PBMCs from four healthy subjects were cocultured for 5 days with IL-2 and PTX (0-1.0 mM). LAKp was inhibited in a PTX dose-dependent manner, as the mean % lysis at an E:T ratio of 50:1 was 62, 43, and 8% in the presence of 0, 0.1, and 1.0 mM PTX, respectively. To determine the effect of in vivo PTX on LAKp activity, four healthy subjects were tested after treatment with PTX at 2 g/day for 3 days. LAKp activity was detected in all four and was not inhibited by autologous serum containing PTX and biologically active metabolites. Because lymphocytes "preactivated" by IL-2 in vivo may respond to PTX differently than resting cells, two patients were tested after a 5 day infusion of IL-2 at 6 x 10(6) U/m2/day. PBMCs from both displayed LAKp activity, with far less inhibition by PTX than in resting cells (4, 17, and 37% inhibition at 0.05, 0.1, and 1.0 mM, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1993

Adverse reactions to intravenous contrast media in patients treated with interleukin-2.

Seventy patients consecutively admitted to a single institution were treated with high-dose interleukin-2 (IL-2) and analyzed for determining the incidence and risk factors associated with reactions to i.v. contrast media. Patients with metastatic renal cancer (n = 44) or melanoma (n = 26) received 74 cycles of IL-2 administered at 2 to 6 x 10(6) U/m2/d for 10-21 days either alone or with lymphokine-activated killer (LAK) cells or tumor-infiltrating lymphocytes (TILs). Seventy-four computed tomography (CT) scans were performed before administration of IL-2; and 74, 59, and 35 CT scans were performed, respectively, 2, 6, and 10 weeks after administration of IL-2. Of the 168 scans performed after therapy with IL-2, non-ionic media were used in 110 and ionic media were used in 58. There were no reactions before administration of IL-2, but there were nine reactions after therapy with IL-2. Reactions to contrast media occurred 1-4 hours after media infusion and included fever, chills, emesis, diarrhea, rash, wheezing, hypotension, edema, and oliguria. Hospitalization was required in seven cases, including intensive care unit support in four, but all patients recovered fully. Contrast reactions were more frequent 2 weeks after therapy with IL-2 (eight of 74 scans, 11%) compared with 6 weeks after IL-2 (one of 59 scans, 1.7%), but the difference was not statistically significant (McNemar's test). Six patients who reacted to contrast 2 weeks after IL-2 treatment received contrast 4 weeks later: five had no reaction and only one experienced a reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Growth and autologous tumor lysis by tumor-infiltrating lymphocytes from metastatic melanoma expanded in interleukin-2 or interleukin-2 plus interleukin-4.

Optimal conditions for expanding tumor-infiltrating lymphocytes (TILs) specifically cytotoxic for autologous melanoma for clinical use have not yet been identified. In several small studies, interleukin (IL)-4 was reported to promote the growth of such TILs in IL-2. Given the potential implications for TIL therapy, we attempted to confirm these findings in a larger study. Baseline data were first obtained on the proliferation, immunophenotype, and cytotoxic reactivity to autologous melanoma of TILs cultured in IL-2 alone. Similar studies were performed with TIL cultured concurrently in either IL-2 alone or in a combination of IL-2 and IL-4. TILs were obtained by excisional biopsy of tumors from 52 patients with metastatic malignant melanoma; TILs from 38 patients were expanded in IL-2 (1,000 U/ml). TILs from 19 biopsies were maximally expanded 6- to 24,000-fold (median, 300-fold) over 4-10 weeks. Expansion did not correlate with the weight of, or number of lymphocytes in, the biopsy specimen, or the site of the biopsy (lymph node vs. subcutaneous metastases). During weeks 5-8, TILs from 19 of 25 biopsy specimens lysed autologous melanoma with little or no lysis of allogeneic melanoma. Lysis of autologous tumor was blocked by antibody to class I antigens. Twenty-four TIL specimens were cultured concurrently in IL-2 alone and in IL-2 plus IL-4 and tested for growth and for lysis of autologous and allogeneic melanomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Cells, Cultured↗
PubMed1993

Interleukin-2 +/- lymphocytes as consolidative immunotherapy after autologous bone marrow transplantation for hematologic malignancies.

Patients who undergo autologous bone marrow transplantation (ABMT) for advanced hematologic malignancies experience a high relapse rate. Therapy with interleukin-2 (IL-2) +/- lymphokine-activated killer (LAK) cells has induced clinical responses in some patients with advanced malignant lymphoma (ML) or acute myelogenous leukemia (AML). It is postulated that IL-2 +/- LAK cells represents a potentially non-cross-resistant therapeutic modality which might prevent or delay relapses if used as consolidative immunotherapy after ABMT, at a time of minimal residual disease. Therefore, we first studied the reconstitution of IL-2-responsive LAK precursor cells after ABMT and found them in the circulation as early as 3 weeks after ABMT. A phase Ib clinical trial was then performed which identified a tolerable IL-2 regimen which could be administered early after ABMT and which could induce immunomodulatory effects. We then initiated a clinical trial to determine the feasibility of generating and administering autologous LAK cells using this IL-2 regimen after ABMT for 16 patients with ML. The results show that IL-2+LAK therapy early after ABMT is feasible but is more toxic than IL-2 alone. Patients with AML on the phase I IL-2 trial and with ML on the IL-2+LAK protocol were evaluated for tumor status. Of 8 patients with AML in first relapse or at a later stage who underwent ABMT and received IL-2, 2 have relapsed, while 6 remain in complete remission 26+ to 40+ (median 28+) months after ABMT. Of 16 patients with ML considered at high risk for relapse who were treated with ABMT+IL-2+LAK, 5 have relapsed, while 11 remain in complete remission at 6+ to 21+ (median 10+) months after ABMT. The results in both trials are quite encouraging and appear to be better than those in nonrandomized historical controls at our institution. Prospectively randomized trials of IL-2 versus no IL-2 after ABMT in such patients are being initiated to assess definitively the effect, if any, on the relapse rate.

Bone Marrow Transplantation↗
PubMed1993

Ischemic stroke in the young: evaluation and age comparison of patients six months to thirty-nine years.

Ischemic stroke in the young is uncommon, but we currently evaluate at least one young stroke patient at our institutions each week. We undertook this chart review of strokes in patients between the ages of 6 months and 39 years to review all conditions associated with, and thus possibly contributory to, the stroke. We also compare younger and older age groups to observe if age-dependent factors exist. Of 100 total ischemic strokes, 22 were in persons 6 months to 18 years and 78 were in persons 19 to 39 years. Seventy-five percent of strokes were associated with a condition known or postulated to increase stroke risk. Some of these conditions are well accepted as causes for stroke, such as some forms of heart disease, whereas others are only postulated, such as the hypercoagulable states. Taken as a whole, associated conditions were approximately equally divided between infectious/inflammatory, structural, and presumed hypercoagulable conditions. Strokes in the first two decades of life were more commonly associated with infectious/inflammatory conditions, whereas strokes in the next two decades more commonly had structural or presumed hypercoagulable associated conditions. Since many strokes remain unexplained, it would be valuable to determine the significance, if any, of conditions less well known as risk factors for stroke.

Adolescent↗
PubMed1993

Assessing patient pain during dental laser treatment.

Patients reported little or no pain during or after treatment with a dental laser. With many people reporting fear of pain as their chief reason for not seeking dental care, lasers may offer a more acceptable treatment technique.

Adolescent↗