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Biomedical subjects

J Marshall

Publications and source records attributed to J Marshall.

At least 109 records · Page 6Linked to original sources
PubMed2000

Specific cytolytic T-cell responses to human CEA from patients immunized with recombinant avipox-CEA vaccine.

Avipox viruses are replication-defective members of the poxvirus family. Avipox-derived vectors such as ALVAC (canarypox) and fowlpox have the ability to infect mammalian cells, including human cells, but do not replicate. The first clinical trial of an avipox recombinant vaccine for patients with advanced carcinomas has recently been conducted using the ALVAC vector and the human carcinoembryonic antigen (CEA) transgene (designated ALVAC-CEA; J. L. Marshall et al, J. Clin. Oncol., 17: 332-337, 1999). The T-cell responses elicited by patients before and after vaccination with the ALVAC-CEA recombinants are characterized in this report. Pre- and postvaccination peripheral blood mononuclear cells (PMBCs) of the eight patients positive for HLA-class I A2 allele, were incubated with the HLA-A2-CEA peptide CAP-1 and interleukin 2. In no cases using prevaccination PMBCs could cultures be established that had the ability to lyse C1R-A2 target cells pulsed with the CAP-1 peptide. However, T-cell cultures from seven of eight of these same patients, obtained from PBMCs after ALVAC-CEA vaccination, were shown to lyse C1R-A2 cells only when pulsed with CAP-1. Moreover, all seven of these T-cell cultures were shown to lyse allogeneic human carcinoma cell lines (SW1463 and SW480) that were both A2+ and expressed CEA; an allogeneic tumor cell line (LS174T) expressing CEA that was negative for A2 expression was not lysed. HLA-A2+ and CEA+ autologous tumor cells were also capable of being lysed by CEA-specific T cells from this patient. Analysis of this CTL line also revealed the expression of several homing and adhesion-associated molecules. Fluorescence-activated cell sorter analysis of the T-cell lines established from patients after ALVAC-CEA vaccination revealed that most were CD8+/CD4-, but many also had a CD8+/CD4+ component. Analyses of T-cell receptor Vbeta usage of several of the CEA-specific CTL lines showed a relatively diverse Vbeta pattern. These studies demonstrate for the first time the ability to vaccinate cancer patients with an avipox recombinant and derive T cells that are capable of lysing allogeneic and autologous tumor cells in a MHC-restricted manner. These studies thus form the rationale to use such replication-deficient recombinant vaccines in future cancer vaccine trials.

Antigen-Presenting Cells↗
PubMed2000

Morphologic preservation and variability of human donor retina.

PURPOSE: To facilitate studies of human retina and utilization of human retinal tissue for treatment of retinal diseases, we studied morphologic preservation in postmortem human retina. METHODS: Morphology of retinas from thirty-one human eyes was examined using light and electron microscopy. The inner and outer retina, rod and cone photoreceptor cells, and central and peripheral retina were compared with regard to morphologic preservation. Possible factors affecting survival were analyzed. RESULTS: The earliest postmortem change was vacuolation of the nerve fiber layer within a few hours postmortem, followed by vacuolation and cytoplasmic swelling of the inner retina. As compared with the inner retina, outer retinal structure was better preserved, i.e., the photoreceptor cells maintained better morphology. Rod cell morphology was better preserved than cone cell morphology, with good preservation of the rod outer segment disc membranes and the inner segment mitochondrial membranes. Thus, well-preserved rod photoreceptor cells were evident in specimens at least 48-hours postmortem. Peripheral retina was better preserved than the central retina including the fovea and perifovea. Factors affecting anatomical integrity included the total time postmortem and, more importantly, the time between death and enucleation. Other factors, including age and sex, did not appear to affect morphological preservation in the present study. CONCLUSIONS: Human retina postmortem remained morphologically intact for a relatively long period of time, with differential preservation among different geographic areas and cell types. This morphologic evidence is consistent with previous findings of functional preservation (e.g. , photoresponses) in such tissue. This study may shed some light on understanding of human retina and its utilization for retinal transplantation.

Adolescent↗
PubMed2000

Pediatric pharmacodynamics of midazolam oral syrup. Pediatric Pharmacology Research Unit Network.

In this study, the authors evaluate the pharmacodynamics, safety, and acceptability of a new cherry-flavored oral syrup formulation of midazolam. This randomized, double-blind, parallel-group, dose-ranging clinical trial of oral midazolam was conducted at seven U.S. health care institutions focused on pediatric clinical pharmacology research (i.e., the PPRU Network). Pediatric patients (n = 85, ages 6 months through 15 years) underwent invasive procedures and were randomized to a single oral dose of midazolam syrup (0.25, 0.5, or 1.0 mg/kg). Patient taste acceptability of midazolam syrup was evaluated at the time of oral administration. Pharmacodynamic measurements included (1) sedation score using a 5-point scale at baseline and 10-, 20-, and 30-minute postdose intervals and (2) anxiety score using a 4-point scale at the time of separation from caretakers and, when applicable, at the time of mask anesthetic induction. Midazolam and alpha-hydroxymidazolam plasma concentrations were measured at all pharmacodynamic measurement time points. Adverse events were monitored continuously during the study. Most patients (99%) accepted the syrup without difficulty. Satisfactory sedation was achieved within 30 minutes by 81% of patients. The anxiety score at the time of caretaker separation and mask anesthetic induction was satisfactory for 87% and 91% of patients, respectively. A significant linear relationship between plasma drug concentration and maximal sedation score, but not anxiety score, was observed. The occurrence of adverse events was consistent with the known safety profile of midazolam. The most commonly reported adverse events were hiccoughing, hypoxemia, nausea, and emesis. It was concluded that a new oral syrup formulation of midazolam, 0.25 to 1.0 mg/kg, effectively induced rapid-onset, dose-related, adequate, and safe sedation and anxiolysis in pediatric patients who underwent operative procedures. Sedative effects were related to plasma concentrations of both midazolam and the primary metabolite, alpha-hydroxymidazolam. Oral midazolam, 1.0 mg/kg, administered within 30 minutes of the expected procedure or anesthetic induction should provide safe and effective sedation to a majority of children ages 6 months to 16 years.

Administration, Oral↗
PubMed2000

Lipoxygenase metabolism following laser induced retinal injury in rabbits.

PURPOSE: 1) to investigate whether leukotriene B(4) (LTB(4)) is a factor in the inflammatory reaction following chorioretinal laser injury in rabbits; 2) to study its relationship with the cyclooxygenase (COX) metabolic pathway; 3) to study the influence of Nordihydroguaiaretic acid (NDGA), an inhibitor; of the lipoxygenase (LOX) cascade, on both COX and LOX metabolism. METHODS: Prostaglandin E(2) (PGE(2)) and LTB(4) synthesis by incubated samples of chorioretina obtained from rabbits' eyes exposed to Neodymium:Yag laser along with these eicosanoids accumulation in the vitreous were measured over one week follow-up period. The effect of NDGA pre-treatment on the COX and the LOX pathways in the laser-injured chorioretina was also assessed. PGE(2) and LTB(4) levels in the vitreous and in the chorioretina incubation medium were quantified using the radioimmunoassay technique with the appropriate antibodies. RESULTS: LTB(4) in vitro production by rabbits' chorioretina subjected to ND; YAG laser was significantly elevated compared to control, peaking on day 7 to levels 2.45 fold greater than baseline (p < 0.01). PGE(2) formation, following a different pattern, was also enhanced and its maximal level (5.2 fold higher than control, p < 0.01) was achieved at the initial phase (day 1 post laser). Laser irradiation caused also an increase in the two eicosanoids accumulation in the vitreous, which was however not proportional to their production levels. NDGA treatment was associated with a sustained decrease in LTB(4) content in the vitreous, but had no effect on PGE(2) vitreal levels. CONCLUSIONS: Laser irradiation of the rabbits' retina induces an alteration in the LOX metabolic pathway, which is dissociated from the influence on the COX cascade, pointing for the first time to a possible role played by LTB( 4) as a mediator in the chorioretinal inflammatory reaction, with no connection to the role played by PGE(2). NDGA selectively inhibited LOX activity without affecting COX activity.

Animals↗
PubMed2000

The impact of displayed awards on the credibility and retention of Web site information.

Ratings systems and awards for medical Web sites have proliferated, but the validity and utility of the systems has not been well established. This study examined the effect of awards on the perceived credibility and retention of health information on a Web page. We recruited study participants from Internet newsgroups and presented them with information on the claimed health benefits of shark cartilage. Participants were randomized to receive health information with and without a medical award present on the page. We subsequently asked them to evaluate the credibility of the Web page and posed multiple-choice questions regarding the content of the pages. 137 completed responses were included for analysis. Our results show that the presentation of awards has no significant effect on the credibility or retention of health information on a Web page. Significantly, the highly educated participants in our study found inaccurate and misleading information on shark cartilage to be slightly believable.

Adult↗
PubMed1999

Increased duration of transgene expression in the lung with plasmid DNA vectors harboring adenovirus E4 open reading frame 3.

For gene therapy to be effective in the treatment of chronic diseases, plasmid DNA (pDNA) vectors that provide persistent expression of therapeutic levels of the transgene product are desirable. Studies in the lung with adenovirus vectors showed that products of the adenovirus E4 region can act both in cis and in trans to increase the duration of expression when transcription of the transgene was under the control of the human cytomegalovirus (CMV) promoter. To determine if these E4-encoded proteins could also effect greater persistence of expression from a nonviral vector, a complex composed of cationic lipid GL-67, a CMV promoter plasmid (pCF1-CAT), and an E4-containing adenovirus vector (Ad2/betagal-4) was instilled into the lungs of BALB/c nu/nu mice. Significant increases in the duration of transgene expression were observed for up to 10 weeks postinstillation compared with expression from mice instilled with control complexes containing an adenovirus vector deleted of most of E4 (Ad2/betagal-2). This effect could also be observed in immunodeficient NIH-rnu rats as well as in immunocompetent BALB/c mice. Studies with CMV promoter mutants indicated that a region proximal to the promoter was necessary for the E4-mediated increase in longevity of expression. In addition to the CMV promoter, a CMV enhancer-human mucin I (MUC-I) hybrid promoter also responded to these E4-encoded proteins with increased persistence of transgene expression, but a human interleukin 8 (IL-8) promoter did not. Ad2/betagal-4 could be replaced by a pDNA vector expressing only the E4 region, indicating that products of the E4 region alone were sufficient in the absence of expression from the rest of the adenovirus genome. Further analysis indicated that the protein encoded by open reading frame 3 (ORF3) alone was sufficient for conferring the increase in persistence of expression. These data indicate that expression of a single protein from the adenovirus genome can significantly improve the duration of transgene expression from pDNA vectors, and increases the feasibility of using nonviral vectors for the treatment of chronic diseases.

Adenoviridae↗
PubMed1999

Behavioural evidence for polarisation vision in stomatopods reveals a potential channel for communication.

Polarisation sensitivity (PS) - the ability to detect the orientation of polarised light - occurs in a wide variety of invertebrates [1] [2] and vertebrates [3] [4] [5], many of which are marine species [1]. Of these, the crustacea are particularly well documented in terms of their structural [6] and neural [7] [8] adaptations for PS. The few behavioural studies conducted on crustaceans demonstrate orientation to, or local navigation with, polarised sky patterns [9]. Aside from this, the function of PS in crustaceans, and indeed in most animals, remains obscure. Where PS can be shown to allow perception of polarised light as a 'special sensory quality' [1], separate from intensity or colour, it has been termed polarisation vision (PV). Here, within the remarkable visual system of the stomatopod crustaceans (mantis shrimps) [10], we provide the first demonstration of PV in the crustacea and the first convincing evidence for learning the orientation of polarised light in any animal. Using new polarimetric [11] and photographic methods to examine stomatopods, we found striking patterns of polarisation on their antennae and telson, suggesting that one function of PV in stomatopods may be communication [12]. PV may also be used for tasks such as navigation [5] [9] [13], location of reflective water surfaces [14] and contrast enhancement [1] [15] [16] [17] [18]. It is possible that the stomatopod PV system also contributes to some of these functions.

Animals↗
PubMed1999

Akt-dependent potentiation of L channels by insulin-like growth factor-1 is required for neuronal survival.

The insulin-like growth factor-1 (IGF-1)/receptor tyrosine kinase recently has been shown to mediate neuronal survival and potentiate the activity of specific calcium channel subtypes; survival requires Akt, a serine/threonine kinase. We demonstrate here that Akt mediates the IGF-1-induced potentiation of L channel currents, but not that of N channels. Transient expression of wild-type, dominant-negative, and constitutively active forms of Akt in cerebellar granule neurons causes, respectively, no change in IGF-1/L channel potentiation, complete inhibition of potentiation, and a dramatic increase in basal L currents accompanied by the loss of ability to induce further increases. In no case is the IGF-1 potentiation of N currents affected. We additionally find that IGF-1 partially mediates granule neuron survival via L channel activity and that Akt-dependent L channel modulation is a necessary component. Interestingly, very brief exposure (1 min) to IGF-1 triggers nearly complete survival and requires L channel activity. These results strongly suggest that neuronal receptor tyrosine kinases can control long-term calcium-dependent processes via the rapid control of voltage-sensitive channels.

Animals↗
PubMed1999

A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. Transfusion Requirements in Critical Care Investigators, Canadian Critical Care Trials Group.

BACKGROUND: To determine whether a restrictive strategy of red-cell transfusion and a liberal strategy produced equivalent results in critically ill patients, we compared the rates of death from all causes at 30 days and the severity of organ dysfunction. METHODS: We enrolled 838 critically ill patients with euvolemia after initial treatment who had hemoglobin concentrations of less than 9.0 g per deciliter within 72 hours after admission to the intensive care unit and randomly assigned 418 patients to a restrictive strategy of transfusion, in which red cells were transfused if the hemoglobin concentration dropped below 7.0 g per deciliter and hemoglobin concentrations were maintained at 7.0 to 9.0 g per deciliter, and 420 patients to a liberal strategy, in which transfusions were given when the hemoglobin concentration fell below 10.0 g per deciliter and hemoglobin concentrations were maintained at 10.0 to 12.0 g per deciliter. RESULTS: Overall, 30-day mortality was similar in the two groups (18.7 percent vs. 23.3 percent, P= 0.11). However, the rates were significantly lower with the restrictive transfusion strategy among patients who were less acutely ill -- those with an Acute Physiology and Chronic Health Evaluation II score of < or =20 (8.7 percent in the restrictive-strategy group and 16.1 percent in the liberal-strategy group; P=0.03) -- and among patients who were less than 55 years of age (5.7 percent and 13.0 percent, respectively; P=0.02), but not among patients with clinically significant cardiac disease (20.5 percent and 22.9 percent, respectively; P=0.69). The mortality rate during hospitalization was significantly lower in the restrictive-strategy group (22.3 percent vs. 28.1 percent, P=0.05). CONCLUSIONS: A restrictive strategy of red-cell transfusion is at least as effective as and possibly superior to a liberal transfusion strategy in critically ill patients, with the possible exception of patients with acute myocardial infarction and unstable angina.

APACHE↗
PubMed1999

Contribution of plasmid DNA to inflammation in the lung after administration of cationic lipid:pDNA complexes.

Cationic lipid-mediated gene transfer to the mouse lung induces a dose-dependent inflammatory response that is characterized by an influx of leukocytes and elevated levels of the cytokines interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and interferon gamma (IFN-gamma). We have examined the contribution of plasmid DNA (pDNA) to this observed toxicity, specifically the role of unmethylated CpG dinucleotides, which have been previously shown to be immunostimulatory. We report here that complexes of cationic lipid GL-67 and unmethylated pDNA (pCF1-CAT) instilled into the lungs of BALB/c mice induced highly elevated levels of the cytokines TNF-alpha, IFN-gamma, IL-6, and IL-12 in the bronchoalveolar lavage fluids (BALF). In contrast, BALF of animals administered either GL-67 alone or GL-67 complexed with SssI-methylated pDNA contained low levels of these cytokines. Similar results were observed using a plasmid (pCF1-null) that does not express a transgene, demonstrating that expression of chloramphenicol acetyltransferase (CAT) was not responsible for the observed inflammation. The response observed was dose dependent, with animals receiving increasingly higher amounts of unmethylated pDNA exhibiting progressively higher levels of the cytokines. Concomitant with this increase in cytokine levels were also elevated numbers of neutrophils in the BALF, suggesting a possible cause- and-effect relationship between neutrophil influx and generation of cytokines. Consistent with this proposal is the observation that reduction of neutrophils in the lung by administration of antibodies against Mac-1alpha and LFA-1 also diminished cytokine levels. This reduction in cytokine levels in the BALF was accompanied by an increase in transgene expression. In an attempt to abate the inflammatory response, sequences in the pDNA encoding the motif RRCGYY, shown to be most immunostimulatory, were selectively mutagenized. However, instillation of a plasmid in which 14 of the 17 CpG sites were altered into BALF/c mice did not reduce the levels of cytokines in the BALF compared with the unmodified vector. This suggests that other unmethylated motifs, in addition to RRCGYY, may also contribute to the inflammatory response. Together, these findings indicate that unmethylated CpG residues in pDNA are a major contributor to the induction of specific proinflammatory cytokines associated with instillation of cationic lipid:pDNA complexes into the lung. Strategies to abate this response are warranted to improve the efficacy of this nonviral gene delivery vector system for the treatment of chronic diseases.

Animals↗
PubMed1999

Glucocorticoids inhibit the expression of calcium-dependent potassium channels in vascular smooth muscle.

Increased calcium-activated potassium channel (KCa) activity in vascular smooth muscle (VSM) cells leads to a relaxation response counteracting the effects of high blood pressure. Since chronic exposure to glucocorticoids (GC) can be associated with an increase in blood pressure, we reasoned that GCs might modify the expression of KCa channels resulting in a net rise in vascular tone. To test this hypothesis, primary cultures of rat VSM cells were exposed to (a) RU 28362 (a pure glucocorticoid receptor agonist), 1 microM; (b) corticosterone 10 nM + carbenoxolone (an inhibitor of bidirectional VSM 11beta-OH steroid dehydrogenase), 1 microM; (c) 11-dehydrocorticosterone (a biologically inactive metabolite), 10 nM + carbenoxolone; (d) carbenoxolone alone; or (e) aldosterone 10 nM for periods of up to 72 h. Proteins were then extracted and Western blots prepared. Gels were probed with a rabbit-derived polyclonal antibody directed against KCa channel protein. The experimental procedure was repeated on separate sets of VSM cells to ensure reproducibility. Expression of KCa channel protein was diminished in VSM cells incubated with corticosterone + carbenoxolone and with RU 28362 after 24 h and remained low at 72 h. Expression of KCa protein in cells exposed to 11-dehydrocorticosterone + carbenoxolone, carbenoxolone alone, and aldosterone was either similar to controls or mildly increased over the 72 h. These data are consistent with the hypothesis that GCs diminish the expression of KCa protein. Diminished KCa expression could contribute to the observed increase in vascular tone following chronic GC exposure.

Androstanols↗
PubMed1999

Morphometric study of the displacement of retinal ganglion cells subserving cones within the human fovea.

BACKGROUND: A study was carried out to measure the displacement of retinal ganglion cells subserving the cones within the human fovea. METHODS: Four human retinas were examined along the nasal or vertical hemi-meridians. Total displacement was estimated by adding the displacement due to fibres of Henle and bipolar cells, measured as the lateral extension of the Henle fibres and of the obliquely running fibre bundles within the inner nuclear layer, respectively. RESULTS: At the foveal border (0.5-0.8 mm or 1.8-2.9 deg eccentricity) the mean offset due to fibres of Henle and mean total lateral displacement was at a maximum of 0.32 +/- 0.03 mm and 0.37 +/- 0.03 mm, respectively. A steep decrease of displacement was found outside the foveal border out to an eccentricity of 2.0-2.5 mm. We were able to plot displacement along the vertical meridian in relation to eccentricity with good correlation between three eyes. The data were used to establish different mathematical functions describing the relation between eccentricity and displacement. These functions were applied to previously presented data on densities of retinal ganglion cells and cones. CONCLUSIONS: The present estimates of displacement within the human central fovea offer the possibility of analysis of quantitative relations between cones and retinal ganglion cells. Our data provide predictive guidance by establishing that vitreo-retinal procedures causing damage to retinal ganglion cells up to 1 mm from the foveal centre could have implications for loss of information generated within the fovea.

Adult↗
PubMed1999

Regression and epithelial hyperplasia after myopic photorefractive keratectomy in a human cornea.

We present the histology of a cornea of a woman who had excimer laser photorefractive keratectomy (PRK) for myopia 6 months before she died in an accident. Preoperative spherical refraction was -6.00 diopters (D) with an astigmatism of -0.50 D. Six months postoperatively, refraction was -4.50 D. Slight corneal haze was noted at 1 and 3 months. The corneal histology showed marked epithelial hyperplasia in the center of the ablation zone without subepithelial deposition of newly synthesized collagen, proteoglycans, or both. The epithelial thickness was 38 microns in the untreated area and 93 microns in the center of the ablation. In conclusion, postoperative epithelial hyperplasia was responsible for regression after PRK in this eye.

Adult↗