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J Leighton

Publications and source records attributed to J Leighton.

At least 19 recordsLinked to original sources
PubMed1998

Phase II study of N-phosphonacetyl-L-aspartate, recombinant interferon-alpha, and fluorouracil infusion in advanced squamous cell carcinoma of the head and neck.

BACKGROUND: 5-Fluorouracil (5-FU), as a single agent, produces a 15% response rate in advanced squamous cell carcinoma of the head and neck (SCCHN). N-phosphonacetyl-L-aspartate (PALA) inhibits pyrimidine biosynthesis and increases incorporation of 5-FU metabolites into ribonucleic acid (RNA). Recombinant alpha interferon-2b (rIFN-alpha-2b) may inhibit 5-FU clearance and blunt reflex rise in thymidylate synthetase, therefore enhancing inhibition of the target enzyme of 5-FU. METHODS: In an attempt to exploit their potential therapeutic synergy, we initiated a phase II trial combining PALA 250 mg/m2 by intravenous (IV) bolus day 1 with 5-FU 2600 mg/m2 24-hour IV infusion initiated 24 hours after PALA, followed by rIFNalpha-2b 10 million units (MU) by subcutaneous injection days 2, 3, and 4 in patients with advanced, measurable SCCHN incurable with surgery or radiotherapy. Treatment was repeated weekly; patients were assessed every 4-6 weeks. Pretreatment tumor specimens were analyzed for p53 mutations in exons 5-8 and for protein expression using the p53 polyclonal antibody CM-1. RESULTS: Nineteen patients were enrolled from November 1991 through February 1994. Median age was 59 years (range, 31-72 years). All had previously received definitive radiotherapy, and all but two had undergone surgical resection. Seven patients (37%) had received prior adjuvant chemotherapy. Median time from initial diagnosis to protocol enrollment was 17 months (range, 5 months to 10 years). Median performance status (PS) was 1. Primary tumor sites included oral cavity (8 patients), larynx (7 patients), oropharynx (3 patients), and hypopharynx (1 patient). The median serum transferrin was 241 (range, 141-333). Sixteen patients (84%) had sufficient pretreatment biopsy material for p53 analysis. Patients received a median of 6 weeks of treatment (range, 2-30 weeks). Six patients (32%) in the absence of disease progression failed to finish the first 6 weeks of treatment: 3 died of pulmonary insufficiency or pneumonia and 3 were removed from study during the first 6 weeks due to toxicity. Grade 2-3 flulike symptoms occurred in 17 patients (89%); grade > or = 3 fatigue occurred in 12 patients (63%), and grade > or = 2 stomatitis occurred in 5 (26%). Gastrointestional toxicity was minimal and myelosuppression mild. Of 13 evaluable patients, there were 2 partial responses (15%) lasting 3 months and 20 months; 5 patients with stable disease lasting 2, 2, 2.5, 3, and 4.5 months; and 6 with disease progression. For all 19 patients, the overall response rate was 11%, the median survival was 6 months and 1-year survival rate 26%. Lower transferrin values (< or =241) were associated with shortened median survival 2.5 vs 11 months). Increased p53 protein expression but not p53 mutations in pretreatment specimens also predicted inferior survival (median, 6 vs 11 months) after enrollment in study (p = .0124). CONCLUSIONS: Biochemical modulation of 5-FU by rIFNalpha-2b and PALA does not enhance its efficacy in patients with advanced SCCHN whose disease has progressed after prior radiotherapy. Serum transferrin and p53 protein expression segregate outcome in this group of uniformly treated patients.

Adult↗
PubMed1995

An ABC transporter in the mitochondrial inner membrane is required for normal growth of yeast.

In an attempt to identify a mitochondrial ATP binding cassette (ABC) transporter, we have used the polymerase chain reaction to amplify 10 DNA fragments homologous to members of the ABC family from the yeast Saccharomyces cerevisiae. We disrupted five of the corresponding genes and found that one of the resulting null mutants barely grew on rich medium and failed to grow on minimal medium. This gene, termed ATM1, encodes a putative 'half-transporter' of 694 amino acids. Atm1p is synthesized with an N-terminal mitochondrial matrix-targeting signal and is located in the mitochondrial inner membrane, with its C-terminal ATPase domain exposed to the matrix. Cells lacking a functional ATM1 gene have an unstable mitochondrial genome and have white mitochondria that completely lack cytochromes. Atm1p is the first mitochondrial member of the ABC family to be identified and the only eukaryotic ABC transporter that has been shown to be necessary for normal cellular growth.

ATP-Binding Cassette Transporters↗
PubMed1995

Paclitaxel and carboplatin in the treatment of advanced non-small cell lung cancer.

Based on the superior response rates (21% to 24%) of patients treated with single-agent paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) in Eastern Cooperative Oncology Group and M.D. Anderson Cancer Center trials in non-small cell lung cancer (NSCLC) and on the superior 1-year survival rates of NSCLC patients treated with carboplatin in a randomized study of cisplatin combination and analogues, we initiated a phase II trial of paclitaxel/carboplatin in patients with stage IV or effusion-positive stage III NSCLC. Eligibility stipulated chemotherapy-naive patients with measurable disease, good performance status, and adequate hematologic, hepatic, and renal function. Previous radiotherapy was restricted to < or = 30% of marrow-bearing bone. Paclitaxel was initially given at 135 mg/m2 over 24 hours followed by carboplatin dosed to a targeted area under the concentration versus time curve (AUC) of 7.5, with treatment repeated at 3-week intervals for six cycles. Granulocyte colony-stimulating factor was introduced during the second and subsequent cycles, with the paclitaxel dose sequentially escalated in 40 mg/m2 increments to a maximum dose of 215 mg/m2 in patients with less than grade 4 granulocytopenia and less than grade 3 thrombocytopenia. Of 54 patients enrolled, 30 currently are evaluable for response, 23 for toxicity. Myelosuppression has been the principal toxicity, with grade 3 or 4 granulocytopenia occurring in 70% of patients after the first cycle. After the introduction of granulocyte colony-stimulating factor, granulocytopenia decreased to 37% during the second cycle and then consistently to 20% or lower during subsequent cycles. Only 22% of cycles have been delayed for 1 week or more. Neutropenic fever has occurred in five (5%) of 100 evaluable cycles. Other grade 3 or 4 toxicities include thrombocytopenia (13%), anemia (9%), fatigue (9%), and hemorrhagic cystitis (1%). The paclitaxel dose was boosted to 215 mg/m2 in 12 (70%) of 17 patients by cycle 3 or 4. At an AUC of 7.5, the median first-cycle carboplatin dose was 434 mg/m2 (range, 293 to 709 mg/m2). The objective response rate is 50%, with three complete, 12 partial, and five minor responses. We conclude that the paclitaxel/carboplatin combination is active in advanced NSCLC and, with AUC-based dosing of carboplatin, can be given at 3-week intervals. Although dose limiting at a paclitaxel dose of 135 mg/m2, granulocytopenia can be reduced substantially with granulocyte colony-stimulating factor, allowing sequential dose escalation of paclitaxel to 175 mg/m2 and 215 mg/m2 in 70% of patients receiving three or more cycles.

Adult↗
PubMed1994

Exploring processes of organization of normal and neoplastic epithelial tissues in gradient culture.

The biology of animal cells in culture is often studied in individual cells or in sheets of cells. The relevance of such studies to the intact animal is unclear, since the spatial conditions encountered by cells in animals is one of dense three-dimensional masses of cells, with limits to migration, and with gradients both of diffusion of metabolites and of morphologic maturation. These spatial requisites have gradually been met in culture. A brief account describes sponge matrix culture for three-dimensional growth and unilaminar, bilaminar, and radial histophysiologic gradient cultures. Some of the common neoplastic abnormalities of surface epithelial tissues are considered. Proposals for investigating the histokinetic mechanisms regulating some epithelial tissue processes are suggested. In the most recent development of gradient culture methods, a thin permeable transparent collagen membrane is intrinsically strengthened by producing a waffle membrane pattern for histophysiologic gradient culture.

Animals↗
PubMed1993

The role of insulin-like growth factors and epidermal growth factor-related peptides in intraovarian regulation in the pig ovary.

The autocrine and paracrine role of the insulin-like growth factors (IGFs) and epidermal growth factor (EGF)-related peptides in pig ovary are reviewed. For convenience, each of these regulatory systems is divided into several interactive components: regulated expression of the growth factors, growth factor reception at the cell surface and intracellular action of the growth factors. In addition, the concept of regulated bioavailability and targeting of growth factors in the extracellular space is developed as an important control locus and area for future study. With regard to the IGF system, these components include two ligands--IGF-I and -II, both expressed in the porcine ovary--and the possibility of three receptors. IGF-I and the type I IGF receptor appear to be the most important in stimulating ovarian function and amplifying hormone action. In addition, the 'set-point' of the ovarian IGF system may be determined by the activity of several IGF-binding proteins (IGFBPs). At least four of these proteins are expressed in the pig ovary. Studies of their regulation and action in ovarian cells indicate that they can function as antagonists to FSH and the IGFs. However, preliminary evidence suggests a more dynamic model in which these proteins may direct the site and timing of IGF effects. There are fewer data on the EGF system. At least four EGF-related peptides are expressed in pig ovaries, but insufficient information is available to predict their physiological regulation. These peptides are potent mitogens for ovarian cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Selective immunosuppression by administration of major histocompatibility complex (MHC) class II-binding peptides. I. Evidence for in vivo MHC blockade preventing T cell activation.

Draining lymph node cells (LNC) from mice immunized with hen egg white lysozyme (HEL) display at their surface antigen-MHC complexes able to stimulate, in the absence of any further antigen addition, HEL peptide-specific, class II-restricted T cell hybridomas. Chloroquine addition to these LNC cultures fails to inhibit antigen presentation, indicating that antigenic complexes of class II molecules and HEL peptides are formed in vivo. MHC class II restriction of antigen presentation by LNC from HEL-primed mice was verified by the use of anti-class II monoclonal antibodies. Coinjection of HEL and the I-Ak-binding peptide HEL 112-129 in mice of H-2k haplotype inhibits the ability of LNC to stimulate I-Ak-restricted, HEL 46-61-specific T cell hybridomas. Similar results are obtained in mice coinjected with the HEL peptides 46-61 and 112-129. Inhibition of T hybridoma activation can also be observed using as antigen-presenting cells irradiated, T cell-depleted LNC from mice coinjected with HEL 46-61 and HEL 112-129, ruling out the possible role of either specific or nonspecific suppressor T cells. Inhibition of T cell proliferation is associated with MHC-specific inhibition of antigen presentation and with occupancy by the competitor of class II binding sites, as measured by activation of peptide-specific T cell hybridomas. These results demonstrate that administration of MHC class II binding peptide competitors selectively inhibits antigen presentation to class II-restricted T cells, indicating competitive blockade of class II molecules in vivo.

Amino Acid Sequence↗
PubMed1992

Expression of messenger RNA for insulin-like growth factors and insulin-like growth factor binding proteins by experimental breast cancer and normal breast tissue in vivo.

We report the expression of insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) by breast cancer cells and normal breast tissue in vivo. N-nitrosomethyl-urea (NMU)-induced rat mammary tumors synthesize mRNAs for IGF-II and IGFBP-2, -3, and -4. In contrast, normal lactating breast contains only IGFBP-2 and IGF-II messages; IGFBP-3 and -4 mRNAs are absent in this tissue. IGF-I and IGFBP-1 mRNAs are not expressed in either NMU tumors or in normal breast. This is the first report of in vivo expression of IGFBPs and IGF-II messages in breast tumors.

Animals↗
PubMed1991

Comparison of structural requirements for interaction of the same peptide with I-Ek and I-Ed molecules in the activation of MHC class II-restricted T cells.

We have analyzed the interaction of the hen egg-white lysozyme (HEL) peptide 107-116 with the MHC class II molecule I-Ek, using truncated and single residue substitution analogues to measure activation of I-Ek-restricted, 107-116-specific T cell hybridomas and competition for Ag presentation by I-Ek molecules. These results have been compared with previous findings on the interaction of the same peptide with the I-Ed molecule. Stimulation of T cell hybridomas by truncated peptides defines the sequence 108-116 as the minimum epitope necessary for activation of both I-Ek- and I-Ed-restricted T cell hybridomas. Substitution analysis pinpoints three residues (V109, A110, and K116) in the sequence 108-116 as being critical for binding to I-Ek molecules and demonstrates the involvement of most other residues in recognition by T cells. Results previously obtained for binding of HEL 107-116 to I-Ed molecules indicated that peptide residues R112, R114, and K116 were critical for interaction with I-Ed. Comparison of these results indicates a difference in the likely MHC contact residues between the HEL sequence 108-116 and I-Ed or I-Ek molecules, suggesting that the same HEL peptide assumes a different conformation in the binding site of these two MHC molecules. This in turn affects residues interacting with the specific T cell receptor. According to the hypothetical tridimensional structure predicted for class II molecules, the difference in MHC contact residues observed within the sequence 108-116 can be related to polymorphic amino acids in the binding site of I-Ek and I-Ed molecules. A search through published binding data for a common pattern in this and other I-Ek-binding peptides has permitted us to derive a possible motif for predicting peptide binding to I-Ek molecules. This putative motif was tested by determining binding to I-Ek of an unbiased panel of about 150 synthetic peptides. Binding data indeed demonstrate the presence of this motif in the majority of good binders to I-Ek molecules.

Amino Acid Sequence↗
PubMed1991

Cyclic AMP mimics, but does not mediate, interleukin-1- and tumour-necrosis-factor-stimulated phospholipase A2 secretion from rat renal mesangial cells.

We have previously shown that recombinant interleukin 1 (IL-1) and recombinant tumour necrosis factor (TNF) synergistically stimulate phospholipase A2 release from mesangial cells. We now report that treatment of mesangial cells with the beta-agonist salbutamol, prostaglandin E2 (PGE2), cholera toxin or forskolin, which all activate adenylate cyclase, increased release of phospholipase A2 activity. Likewise, addition of a membrane-permeant cyclic AMP (cAMP) analogue or the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine enhanced release of phospholipase A2 activity from mesangial cells. There was a lag period of about 8 h before a significantly enhanced secretion could be detected. Furthermore, actinomycin D or cycloheximide completely suppressed cAMP-stimulated secretion of phospholipase A2. Angiotensin II, the phorbol ester phorbol 12-myristate 13-acetate, the Ca2+ ionophore A23187 and a membrane-permeant cGMP analogue did not stimulate phospholipase A2 release from the cells. Treatment with indomethacin completely inhibited IL-1 beta- and TNF-stimulated PGE2 synthesis, without having any effect on phospholipase A2 secretion, thus excluding cytokine-induced PGE2 synthesis as the mediator of phospholipase A2 release. Neither IL-1 beta nor TNF induced any increase in intracellular cAMP in mesangial cells. Furthermore, incubation of the cells with 2',5'-dideoxyadenosine, an inhibitor of adenylate cyclase, did not block cytokine-stimulated phospholipase A2 secretion. In addition, IL-1 beta and TNF synergistically interacted with forskolin to stimulate phospholipase A2 release from the cells. The protein kinase inhibitors H-8, staurosporine, K252a and amiloride inhibited IL-1 beta- and TNF-stimulated phospholipase A2 secretion. However, high concentrations that inhibit other protein kinases were needed. These observations suggest that IL-1 beta and TNF cause secretion of phospholipase A2 by a mechanism independent of cAMP. The signalling pathways used by IL-1 beta and TNF may involve a protein kinase that is probably different from protein kinase A or protein kinase C.

Animals↗
PubMed1991

Radial histophysiologic gradient culture chamber: rationale and preparation.

Histophysiologic gradient culture methods reconstitute important spatial relationships that occur in nature between a parenchyma and its supporting stroma. At the epithelial-stromal interface, epithelia are firmly attached to the stromal substrate, initiation of renewal takes place, and metabolites are exchanged by a process of diffusion between epithelium and substrate. Other spatial imperatives characteristic of stratified epithelium are high density of cells, gradients of maturation, and continuity of epithelia along the entire course of the stromal-parenchymal interface. In radial gradient culture these relationships of epithelial cells, and supporting substrates are reconstituted. The culture chamber consists of a thin-walled cylinder, 2 to 3 mm in diameter and 3 cm long. The wall is a transparent collagen membrane in whose substance is embedded a reinforcing nylon mesh. To prepare a culture, one end of the cylinder is ligated, 1 or 2 particulate inocula are inserted in the open end of the cylinder, guided toward the ligature, and the open end is ligated. Subsequently, during incubation in a container with medium, the explants attach and proliferate. Proliferation and migration result in the cylinder being completely lined by a complex organoid tissue with structural characteristics of the original tissue. The tissue patterns in radial gradient culture of two human cell lines, RT-4, a bladder cancer, and 87 x 50, an ovarian cancer, are illustrated.

Cell Line↗
PubMed1990

Transforming growth factor beta 2 differentially modulates interleukin-1 beta- and tumour-necrosis-factor-alpha-stimulated phospholipase A2 and prostaglandin E2 synthesis in rat renal mesangial cells.

Treatment of rat glomerular mesangial cells with transforming growth factor beta 2 (TGF beta 2) stimulates prostaglandin E2 (PGE2) synthesis. Actinomycin D, cycloheximide and diclofenac attenuate the TGF beta 2-induced PGE2 formation. As shown previously, two proinflammatory cytokines, interleukin 1 beta (IL-1 beta) and tumour necrosis factor alpha (TNF alpha), are potent stimuli for PGE2 and phospholipase A2 secretion from mesangial cells. We report here that, whereas TGF beta 2 potentiates the IL-1 beta- and TNF alpha-evoked PGE2 production, it strongly inhibits the phospholipase A2 secretion induced by both cytokines. In addition, the inhibitory effect of TGF beta 2 on phospholipase A2 secretion is not due to the augmented PGE2 formation.

Animals↗
PubMed1989

Reconstitution of the malignant phenotype of genitourinary cancer in gradient culture.

The diagnosis of cancer is made on histologic examination by recognizing the characteristics of the malignant phenotype, i.e. abnormal cells in abnormal groupings, often in abnormal locations. Histophysiologic gradient culture reconstitutes conditions that meet the spatial imperatives of tissues in nature. A variety of carcinomas arise in the genitourinary system involving both glandular and stratified epithelium. To be considered here are the contrasting polarizations of proliferation of normal and neoplastic rat urothelium, the continuity of sheets of epithelium in nature, the poorly understood stable and unstable interepithelial boundaries, and the formation of organoid endocrinelike tissue in histophysiologic gradient culture of normal human amnion epithelium.

Adenocarcinoma↗
PubMed1988

The National WIC Evaluation: evaluation of the Special Supplemental Food Program for Women, Infants, and Children. II. Review of past studies of WIC.

We reviewed past work relating WIC benefits to birth weight, perinatal and infant survival, anemia, child growth, and dietary intake. Despite many uncertainties, the probable range of reduction in the rate of low birth weight was approximately 1-2% and the increase in mean birth weight ranged from 0 to approximately 60 g. There was too little information to securely estimate effects of WIC on perinatal and infant mortality nor on the dietary intake of women or children. Although the number of studies was small, there probably were important effects of WIC on rates of childhood anemia. There is too little evidence to come to any conclusion on effects during pregnancy. There is little evidence that the WIC program has affected children's linear growth.

Birth Weight↗
PubMed1988

The National WIC Evaluation: evaluation of the Special Supplemental Food Program for Women, Infants, and Children. IV. Study methodology and sample characteristics in the longitudinal study of pregnant women, the study of children, and the food expenditures study.

The longitudinal study of pregnant women enrolled a national probability sample of 5,205 women first certified for WIC and 1,358 comparable low-income pregnant women in 174 WIC clinics located in 58 areas in the contiguous 48 states and in 55 prenatal clinics without WIC programs in counties with low program coverage. The women completed 24-h dietary recalls, histories of food expenditures, health care utilization, health and sociodemographic status, and anthropometric assessment. At late-pregnancy follow-up 3,967 WIC and 1043 control women were interviewed and 853 WIC and 762 control women completed 1-wk food expenditure diaries. Birth outcome was abstracted (from hospital records) for 3,863 WIC and 1058 control women. Anthropometry, dietary intake, health, and use of health services were related to WIC among 2,619 random low-income preschoolers. Psychological development was assessed in 526 children aged 4 and 5 y. Control women had higher income, education, and employment status; therefore, WIC program benefits probably were underestimated.

Child Nutritional Physiological Phenomena↗