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Biomedical subjects

C Carter

Publications and source records attributed to C Carter.

At least 127 records · Page 7Linked to original sources
PubMed1994

Propagation of mouse and human T cells with defined antigen specificity and function.

Difficulties maintaining fully functional CD4+ T cells in culture have historically limited the study of their role in tumour rejection as well as other clinical applications. As the therapeutic value of current antitumour CD8+ T cell adoptive therapy becomes better defined, a strong impetus exists to determine optimal conditions for culturing antitumour CD4+ T cells. Our goal is to promote broadly polyclonal, antigen-specific CD4+ T cell responses of either Th1 or Th2 character for use in antitumour therapy or allograft facilitation, respectively. Similar obstacles exist in murine and human cultures: (1) during even brief periods of culture CD4+ T cells develop high 'background' reactivity to class II-positive antigen-presenting cells; (2) maintenance of antigen specificity as evidenced by cytokine secretion and short-term proliferation assays is insufficient to ensure bulk numerical expansion; (3) Th1-type CD4+ T cells often lose their potential for antigen-specific secretion of interleukin 2 on re-stimulation (though remain inducible by 12-O-tetradecanoylphorbol 13-acetate/ionomycin); (4) during prolonged culture selection pressure favours CD4+ subpopulations that recognize artifactual antigens such as culture medium proteins; (5) even with optimal culture conditions, cultured CD4+ T cells may function differently in vivo to uncultured CD4+ T cells. We have devised various strategies to surmount these obstacles by use of selected cytokines, antigen-presenting cells and timely culture manoeuvres.

Animals↗
PubMed1994

Randomized comparison of fine-needle aspiration cytology and Biopty-Cut needle biopsy after unsatisfactory initial cytology of discrete breast lesions.

In a minority of patients with a discrete breast lump the initial cytological assessment is either unsatisfactory or at variance with the results of other methods of diagnosis. A randomized comparison of repeat cytology and needle-core biopsy provided clinically useful information in 14 of 31 patients receiving repeat cytology and in 26 of 29 randomized to core biopsy. Nineteen patients had carcinoma: ten who received repeat cytology, which indicated malignancy in only three (diagnostic of malignancy in one, suspicious in two), while all nine patients who underwent core biopsy had a correct diagnosis (only suspicious of malignancy in one). The sensitivity for the definitive diagnosis of carcinoma on repeat cytology and core biopsy was 10 and 89 per cent respectively. Patients with a discrete breast lump and unclear cytology results require needle-core biopsy. This has more diagnostic value than repeat cytology.

Adult↗
PubMed1994

Pulsed field gel electrophoretic analysis of the rat major histocompatibility complex class III region shows extensive inter-species conservation.

Using pulsed field gel electrophoresis (PFGE), we have examined the rat major histocompatibility complex (MHC) for the presence of a number of new class III region genes recently identified in the human MHC. We find homologous genes to the human G1, G2, G4, G7a, G9, G9a, G10, G13, G15, and G18 genes, but not the G8 gene in the rat genome, and show that these are linked to the rat TNF-alpha and C4/Slp loci. A long-range restriction map has been constructed on the basis of a PFGE analysis which demonstrates extensive co-linearity in the positions of the homologous sequences in the region between the C4/Slp and TNF loci in the rat MHC when compared with that of the human MHC class III region.

Animals↗
PubMed1994

Histopathological analysis of metastatic melanoma deposits in patients receiving adoptive immunotherapy with tumor-infiltrating lymphocytes.

Tumor-infiltrating lymphocytes (TIL) from a wide range of human and murine tumors can be expanded in vitro using interleukin-2 (IL-2). These TIL are cytolytic T lymphocytes with in vivo and in vitro antitumor activity in mice and in humans. TIL from human melanoma can recognize autologous tumor in an MHC-restricted fashion, localize in vivo after 111In labeling, and mediate regression of large metastatic deposits. Although studied extensively in vitro, less is known in vivo about TIL activity associated with tumor regression. This study was undertaken, in association with a study of TIL localization, to investigate mechanisms of TIL action by evaluating histopathological changes that occur at the tumor site during TIL administration. A total of 106 pre- and post-treatment pathological specimens from 25 patients enrolled in phase II TIL treatment and 111In-TIL imaging protocols were examined blindly by a single pathologist. Histological subtype, lymphocytic infiltration, melanin content, vascularity, and necrosis were documented for each tumor specimen. Average baseline and post-treatment parameters were compared. Any significant changes were evaluated for correlation with clinical response and 111In-TIL localization to tumor. Melanin content and vascularity of the tumor did not change as a result of therapy or correlate with either response or TIL localization. However, both increased lymphocytic infiltration and tumor necrosis were present after TIL administration (P = 0.044 and 0.032 respectively). Furthermore, increases in lymphocytic infiltration correlated with tumor imaging using 111In-TIL, and with the percentage of 111In-labeled injectate present per gram of tumor specimen (P = 0.036 and 0.0041 respectively). This suggests that TIL either account for the increased lymphocytes directly, or localize to tumor and recruit endogenous lymphocytes. We were unable to demonstrate any pretreatment histopathological predictors of response or variables that significantly correlated with subsequent clinical response, although peak and average values of necrosis were higher in responding patients compared to non-responding patients.

Cohort Studies↗
PubMed1994

NMDA receptors with different sensitivities to magnesium and ifenprodil control the release of [14C]acetylcholine and [3H]spermidine from rat striatal slices in vitro.

KCl (20-100 mM) and N-methyl-D-aspartate (NMDA, 100-1,000 microM) produce concomitant concentration-dependent increases in the release of previously captured [14C]acetylcholine and [3H]spermidine from rat striatal slices in vitro. The effects of NMDA (300 microM) on striatal [14C]acetylcholine and [3H]spermidine release were blocked with equal potencies by the competitive NMDA antagonist CGP 37849, the glycine site antagonist L-689,560, and the NMDA channel blocker dizocilpine. In contrast, although NMDA-evoked [14C]acetylcholine release was antagonized by ifenprodil (IC50 = 5.3 microM) and MgCl2 (IC50 = 200 microM), neither compound antagonized the NMDA-evoked release of [3H]spermidine at concentrations up to 100 microM (ifenprodil) or 1 mM (MgCl2). Distinct NMDA receptor subtypes with different sensitivities to magnesium and ifenprodil therefore exist in the rat striatum.

2-Amino-5-phosphonovalerate↗
PubMed1994

Autoradiographic distribution and characteristics of high- and low-affinity polyamine-sensitive [3H]ifenprodil sites in the rat brain: possible relationship to NMDAR2B receptors and calmodulin.

We have studied the regional distribution and characteristics of polyamine-sensitive [3H]ifenprodil binding sites by quantitative autoradiography in the rat brain. In forebrain areas ifenprodil displaced [3H]ifenprodil (40 nM) in a biphasic manner with IC50 values ranging from 42 to 352 nM and 401 to 974 microM. In hindbrain regions, including the cerebellum, ifenprodil displacement curves were monophasic with IC50 values in the high micromolar range. Wiping studies using forebrain slices (containing both high- and low-affinity sites) or cerebellar slices (containing only the low-affinity site) showed that high- and low-affinity ifenprodil sites are sensitive to spermine and spermidine, to the aminoglycoside antibiotics neomycin, gentamicin, and kanamycin, and to zinc. Two calmodulin antagonists, W7 and calmidazolium, also displaced [3H]ifenprodil from both sites. Other calmodulin antagonists, including trifluoperazine, prenylamine, and chlorpromazine, selectively displaced [3H]ifenprodil from its low-affinity site in hindbrain and forebrain regions. High-affinity [3H]ifenprodil sites, defined either by ifenprodil displacement curves or by [3H]ifenprodil binding in the presence of 1 mM trifluoperazine, were concentrated in the cortex, hippocampus, striatum, and thalamus with little or no labeling of hindbrain or cerebellar regions. This distribution matches that of NMDAR2B mRNA, supporting data showing that ifenprodil has a preferential action at NMDA receptors containing this subunit. Low-affinity [3H]ifenprodil sites have a more ubiquitous distribution but are especially concentrated in the molecular layer of the cerebellum. [3H]ifenprodil was found to bind to calmodulin-agarose with very low affinity (IC50 of ifenprodil = 516 microM). This binding was displaced by calmodulin antagonists and by polyamines, with a potency that matched their displacement of [3H]ifenprodil from its low-affinity site in brain sections. However, the localization of the low-affinity [3H]ifenprodil site does not strictly correspond to that of calmodulin, and its identity remains to be further characterized. The restricted localization of high-affinity [3H]ifenprodil binding sites to regions rich in NMDAR2B subunit mRNA may explain the atypical nature of this NMDA antagonist.

Animals↗
PubMed1994

Proteolytic activity of novel human immunodeficiency virus type 1 proteinase proteins from a precursor with a blocking mutation at the N terminus of the PR domain.

The mature human immunodeficiency virus type 1 proteinase (PR; 11 kDa) can cleave all interdomain junctions in the Gag and Gag-Pol polyprotein precursors. To determine the activity of the enzyme in its precursor form, we blocked release of mature PR from a truncated Gag-Pol polyprotein by introducing mutations into the N-terminal Phe-Pro cleavage site of the PR domain. The mutant precursor autoprocessed efficiently upon expression in Escherichia coli. No detectable mature PR was released; however, several PR-related products ranging in size from approximately 14 to 18 kDa accumulated. Products of the same size were generated when mutant precursors were digested with wild-type PR. Thus, PR can utilize cleavage sites in the region upstream of the PR domain, resulting in the formation of extended PR species. On the basis of active-site titration, the PR species generated from mutated precursor exhibited wild-type activity on peptide substrates. However, the proteolytic activity of these extended enzymes on polyprotein substrates provided exogenously was low when equimolar amounts of extended and wild-type PR proteins were compared. Mammalian cells expressing the mutated precursor produced predominantly precursor and considerably reduced amounts of mature products. Released particles consisted mostly of uncleaved or partially cleaved polyproteins. Our results suggest that precursor forms of PR can autoprocess but are less efficient in processing of the Gag precursor for formation of mature virus particles.

Amino Acid Sequence↗
PubMed1994

DETERMINATION OF PROTEIN SYNTHESIS IN RAINBOW TROUT, ONCORHYNCHUS MYKISS, USING A STABLE ISOTOPE

It has been suggested (Houlihan, 1991) that the consumption of 1 g of protein in a variety of species of fish stimulates the synthesis of, approximately, an equal amount of protein. Although synthesis of protein may account for as much as 40 % of the whole-animal oxygen consumption (Lyndon et al. 1992), only about 30 % of the synthesized proteins are retained as growth (Houlihan et al. 1988; Carter et al. 1993a,b). Thus, one focus of attention is the potential advantage gained by fish in allocating a considerable proportion of assimilated energy to protein turnover in contrast to relatively low-cost, low-turnover protein growth (Houlihan et al. 1993). Rates of protein synthesis in several species of fish have been measured using radioactively labelled amino acids, frequently given as a flooding dose (reviewed by Fauconneau, 1985; Houlihan, 1991). These measurements cannot be made for longer than a few hours because of the decline in specific radioactivity in the amino acid free pool. However, as protein synthesis rates vary during the course of a day as a result of the post-prandial stimulation, and since radiolabelled amino acid methodology is invasive, short-term and terminal, it has been difficult to be certain of the relationship between protein growth measured in the long term and protein synthesis rates measured in the short term. This paper addresses these problems by developing a method using 15N in orally administered protein to measure protein synthesis rates in fish over relatively long periods, the aim being to use procedures that are as non-invasive and repeatable as possible. The use of stable isotopes to measure protein metabolism is well established in terrestrial mammals (see Rennie et al. 1991; Wolfe, 1992), but to our knowledge the only published data for aquatic ectotherms are on the blue mussel (Mytilus edulis L.) (Hawkins, 1985). In the present study, rates of protein synthesis of individual rainbow trout [Oncorhynchus mykiss (Walbaum)] were calculated from the enrichment of excreted ammonia with 15N over the 48 h following the feeding of a single meal (dose) containing protein uniformly labelled with 15N by use of an end-point stochastic model (Waterlow et al. 1978; Wolfe, 1992). Application of this type of modelling would appear to be ideal for measuring ammonotelic fish nitrogen metabolism since, unlike the situation in mammals, the catabolic flux of amino acids through urea is very small. Further, ammonia is excreted directly into the surrounding water via the gills and is not stored for any length of time, in contrast to the situation in mammals, so the rate of tracer appearance is easily measurable.

Journal Article↗
PubMed1994

Adinazolam sustained-release treatment of panic disorder: a double-blind study.

Two hundred six outpatients with panic disorder and agoraphobia were randomly assigned to receive 4 weeks of treatment with placebo or sustained-release adinazolam under double-blind conditions. Eighty-eight percent of patients receiving drug and 85% of patients receiving placebo remained in the study at week 4. This report describes the "intent-to-treat" analysis of 202 patients who made at least one follow-up visit after randomization at baseline. On the basis of the Clinical Global Impressions-Improvement Scale, 69.7% of the adinazolam-treated patients were much or very much improved compared with 39.6% of the placebo-treated patients at week 4 or end-point (p = 0.0001). At week 4, panic attacks were completely blocked in 57.1% of adinazolam-treated patients and in 39.2% of the placebo-treated patients (p = 0.009). Adinazolam sustained-release treatment was statistically more effective than placebo treatment on measures of global improvement, number of panic attacks, SCL-90 phobia severity, main phobia severity, and anticipatory and general anxiety. No drug-placebo differences were found for overall self-rated phobia severity, unexpected or situational panic attacks, or for work, family, or social disability.

Adult↗
PubMed1994

The alpha-mannosidase of Trypanosoma cruzi: structure and function.

Trypanosoma cruzi alpha-mannosidase has been purified to apparent homogeneity. It is a 240,000-Da tetramer composed of four identical subunits (58,000 Da). Each subunit contains one N-linked high-mannose oligosaccharide. Based on pH optimum and sensitivity to inhibition by swainsonine, we suggest it to be lysosomal, but this has yet to be demonstrated directly. The enzyme appears to be developmentally regulated and may be a key enzyme in the degradation of the lipopeptidophosphoglycan (LPPG) during transformation from epimastigote to trypomastigote. Preliminary experiments suggest T. cruzi does not utilize the mannose 6-phosphate recognition system for sorting alpha-mannosidase (or other acid hydrolases) to the lysosome. To clone the alpha-mannosidase from T. cruzi we have used the same approach that has been used for other alpha-mannosidases. The cDNA amplification product was subcloned and sequenced. Comparison of the T. cruzi alpha-mannosidase sequence with the alpha-mannosidases that were used in the original primer design demonstrated a greater similarity to murine lysosomal and Dictyostelium alpha-mannosidases than to Golgi alpha-mannosidases.

Animals↗
PubMed1994

An examination of winners and losers under Medicare's prospective payment system.

Through case studies of 10 matched pairs of winner and loser hospitals under the Medicare prospective payment system (PPS), specific characteristics and management actions were identified that are related to strong financial performance. Because other payers are increasingly adopting PPS-like cost control incentives and because managed care is fundamental to the national health care reform debate, the successful strategies identified in this article may be of increasing importance to hospital managers.

Cost Control↗
PubMed1993

Ornithine decarboxylase inhibition or NMDA receptor antagonism reduce cortical polyamine efflux associated with dialysis probe implantation.

Dialysis probe implantation in the rat parietal cortex results in delayed, prolonged and biphasic increases in the efflux of putrescine and spermidine with primary and secondary efflux peaks 6-8 h and 20-24 h after implantation. Putrescine and spermidine efflux remain elevated for at least 30 h after implantation. The primary efflux peak is attenuated by the continual infusion via the dialysis probe of either the ornithine decarboxylase inhibitor difluoromethylornithine or by the NMDA antagonist 2-APV. The secondary peak is resistant to either of these treatments. These changes in polyamine outflow are likely related to the traumatic brain damage associated with dialysis probe implantation which may be a useful model to study the effects of local brain trauma.

2-Amino-5-phosphonovalerate↗
PubMed1993

Infection of mononucleated phagocytes with human cytomegalovirus.

Human cytomegalovirus (HCMV) can be isolated from peripheral blood leukocytes; however, in vitro, only abortive infection of monocytes, lymphocytes, and granulocytes has been detected. These studies demonstrate that freshly isolated monocytes can be infected with HCMV. Infection of monocytes was not associated with loss of cell viability. The virus replication cycle in monocytes resembled that observed in fibroblasts but the virus yield was approximately 0.1% of that observed in fibroblasts. Transient phenotypical changes occurred in HCMV-infected monocytes. Virus persists in infected monocytes upon differentiation to macrophages, suggesting that monocytes may serve as a carrier of HCMV and a vector for viral dissemination. Differentiated mononuclear phagocytes appear to support a productive HCMV infection. Using a recombinant HCMV strain to express beta-galactosidase, we were able to transduce the bacterial beta-galactosidase gene into monocytes and macrophages.

Antigens, Viral↗
PubMed1993

Pulse oximetry, capnography, and blood gas measurements: reducing cost and improving the quality of care with technology.

Pulse oximetry appears to improve quality of care by the early detection of hypoxia noninvasively. We tested the hypothesis that the widespread use of pulse oximetry over a 5-year period in the operating rooms at our institution had resulted in a reduction in blood gas measurements and in departmental operating costs. The total number of blood gas determinations per hour of anesthetic time at our institution decreased by 44%, from 7.64 to 4.26 measurements per 100 operating room hours. The number of capnography units in the operating rooms increased from 8 to 14, the number of pulse oximeters increased from 0 to 22, and oximeter use increased from 0 to 100% for all anesthetics. The total cost to provide oximetry, capnography, and blood gas measurements in 1989-1990 was less than the cost to provide blood gas measurements alone in 1985-1986. The introduction of these technologies was accomplished without an increase in cost: $76,880 in 1985-1986 versus $71,025 in 1989-1990.

Anesthesiology↗
PubMed1993

Treatment of severe combined immunodeficiency disease (SCID) due to adenosine deaminase deficiency with CD34+ selected autologous peripheral blood cells transduced with a human ADA gene. Amendment to clinical research project, Project 90-C-195, January 10, 1992.

Significant increases in lymphocyte adenosine deaminase activity, T cell numbers and immune function have been achieved in the two children with SCID thus far treated with autologous T cells genetically-corrected by retroviral-mediated insertion of a normal ADA gene. Although the data obtained to date demonstrate that the use of ADA gene corrected peripheral T cells appears to be an effective treatment for ADA(-)SCID, it is theoretically preferable to try to develop a treatment for these children that will result in stem cell gene correction. The genetic correction of T cell progenitors with long-term immune reconstituting ability would be more desirable because repeated infusions of genetically altered cells should not be necessary and the generation of a more complete repertoire of T cell specificities might also be possible. Furthermore, the present treatment protocol involves indefinite continuation of enzyme replacement treatment with PEG-ADA. The demonstration of ADA gene expression in the progeny of transduced stem cells may simplify the decision concerning cessation of this very costly enzyme treatment (approximately $250,000/yr./patient). Recent evidence suggests that a small fraction of bone marrow or peripheral blood mononuclear cells bearing the CD34 antigen contains hematopoietic stem cells with both lymphoid and myeloid reconstituting ability. We propose in this amendment to supplement the infusion of human ADA gene-transduced autologous T cells in children with ADA(-)SCID with autologous peripheral blood CD34+ cells transduced with a second, readily distinguishable ADA vector.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Deaminase↗