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T Hamilton

Publications and source records attributed to T Hamilton.

At least 19 recordsLinked to original sources
PubMed1998

Impaired activation of NFkappaB in T cells from a subset of renal cell carcinoma patients is mediated by inhibition of phosphorylation and degradation of the inhibitor, IkappaBalpha.

Activation of the transcription factor NFkappaB in peripheral blood T cells from patients with renal cell carcinoma (RCC) is compromised. This impaired signaling function results from a failure of RelA and c-Rel to translocate to the nucleus though normal levels of Rel proteins are present in the cytoplasm. We demonstrate here in a subset of RCC patients that the defect in NFkappaB activation is attributable to the absence of phosphorylation and degradation of the inhibitor IkappaBalpha. In patient T cells there was no stimulus dependent decrease in the cytoplasmic level of IkappaBalpha. Coimmunoprecipitation studies showed that RelA was in complex with IkappaBalpha and was not released after stimulation. Moreover, the phosphorylated form of IkappaBalpha detected in normal T cells after activation is absent in patient T cells. Additional experiments showed that soluble products from RCCs (RCC-S) can reproduce the same phenotype in T cells from healthy individuals. Supernatant fluid from cultured explants of RCC, but not normal kidney, inhibited the stimulus dependent nuclear translocation of NFkappaB without altering the cytoplasmic levels of RelA, c-Rel, and NFkappaB1. Phosphorylation and degradation of IkappaBalpha was also blocked by RCC-S. The mechanistic similarities between patient-derived T cells and normal T cells cultured with RCC-S suggest that the tumor-derived products may be the primary mediators of impaired T-cell function in this tumor system.

Biological Transport↗
PubMed1998

Long-term effectiveness and safety of recombinant human interferon gamma therapy for atopic dermatitis despite unchanged serum IgE levels.

OBJECTIVE: To assess the long-term effects of recombinant human interferon gamma treatment of atopic dermatitis (AD). DESIGN: Case series. Patients were treated for up to 24 months. SETTING: University dermatology outpatient clinics in Ann Arbor, Mich, and Portland, Ore. PATIENTS: Twenty-four of 32 eligible patients who participated in a previously reported, 12-week, double-blind, placebo-controlled study of recombinant human interferon gamma treatment for AD were enrolled. INTERVENTION: Patients self-administered recombinant human interferon gamma, 50 microg/m2, by daily subcutaneous injection. MAIN OUTCOME MEASURES: Overall response; body surface area of involvement; clinical severity scores for pruritus, erythema, edema, excoriations, dryness, scaling, and lichenification; other atopic symptoms; and laboratory parameters, including serum IgE levels, were monitored at quarterly visits. Results at 1 and 2 years were compared with baseline values. RESULTS: All efficacy parameters improved (P<.05). For example, pruritus was reduced by 50% after both 1 (n=24, P<.001) and 2 (n=16, P=.005) years. Allergic conjunctivitis and allergic rhinitis also improved (P<.01). Eosinophil counts decreased significantly (P<.001). IgE levels increased. Clinical improvement more closely correlated with changes in eosinophil counts (r=0.3-0.5) than with changes in IgE levels (r=0.0-0.2). Only 1 patient discontinued therapy because of adverse effects (flulike symptoms). CONCLUSIONS: The initial efficacy and adverse effects reported for recombinant human interferon gamma treatment of patients with AD were maintained after 2 years of long-term use. Recombinant human interferon gamma seems to be a well-tolerated and effective agent in the long-term therapy of patients with AD. Therapies that correct cellular immune defects, but not humoral immune defects, may be effective in the treatment of patients with AD.

Adolescent↗
PubMed1998

Multiple primary melanomas.

BACKGROUND: The diagnosis of primary melanoma increases the risk of additional primary melanomas. OBJECTIVE: We characterize the subgroup of patients with multiple melanomas. METHODS: We reviewed the melanoma database. RESULTS: Sixty patients with multiple primary melanomas were identified. Twelve (20%) experienced melanomas in the same regional location, 43 (72%) in different locations, and 5 (8%) in both the same and different locations (> 2 melanomas). Eighteen (30%) were diagnosed concurrently with multiple melanomas, 38 (63%) subsequently, and 4 (7%) concurrently and subsequently (>2 melanomas). Forty-two percent of subsequent melanomas occurred within 3 years of the initial lesion diagnosis, 9 (17%) between 3 and 7 years, and 22 (42%) after more than 7 years. Subsequent melanomas were thinner in 70% of cases (P = .05). The mean age at first melanoma diagnosis was 38 and 59 years, respectively, for those with and without dysplastic nevi (P < .001). CONCLUSION: In patients with multiple melanomas, subsequent melanomas often occur in different regional locations several years after diagnosis of the initial lesion.

Age of Onset↗
PubMed1998

Sensitivity of cross-reacting antihuman antibodies in formalin-fixed porcine skin: including antibodies to proliferation antigens and cytokeratins with specificity in the skin.

Although no animal is a perfect skin model for the study of toxicological and therapeutic agents, structurally the pig may be superior to even non-human primates. Because our work involves effects of toxicological and therapeutic agents on the skin, we wanted to identify stains which may prove useful as well as determine cross-reactivity of some newer antihuman antibodies. We performed a battery of formalin-fixed skin from weanling pigs and minipigs. The battery of antibodies included LCA, CD3, OPD-4, CD34, UCHL-1, L-26, KP-1, MAC-387, Factor XIIIa, Leu-7, S-100 protein, HMB-45, GFAP, synaptophysin, neurofilament protein, ubiquitin, vimentin, type IV collagen, laminin, fibronectin, Factor VIII related antigen, Desmin-M, smooth muscle actin, cytokeratin 7, cytokeratin 20, AEI/AE3, CAM 5.2, EMA, GCDFP, Ki-67, and PCNA. Immunohistochemical stains for CD3, Leu-7, S-100 protein, type IV collagen, laminin, Factor VIII related antigen, GFAP, synaptophysin, neurofilament protein, ubiquitin, smooth muscle actin, vimentin, Desmin-M, cytokeratin 7, cytokeratin 20, AE1/AE3, CAM 5.2, Ki-67 and PCNA showed consistent cross-reactivity. In formalin-fixed tissue, only antibodies to lymphoreticular cells showed poor cross-reactivity. A high percentage of the remaining antibodies did show good cross-reactivity but with some interesting similarities and differences in specificity.

Animals↗
PubMed1998

Histopathologic and immunohistochemical features in human skin after exposure to nitrogen and sulfur mustard.

N-methyl-2,2'-dichlorodiethylamine (HN2)is a topical chemotherapeutic agent used as therapy for cutaneous T-cell lymphomas (CTCL). Di(2-chloroethyl)sulfide (SM), and less often HN2, have been used as chemical weapons, with the skin being a principle target. The mechanisms by which these chemicals produce their therapeutic and toxic effects in skin, however, are not clearly defined. We exposed human skin explants to two doses of HN2 and SM. At 18 hours after exposure, histopathologic features were compared. In addition, immunohistochemical markers to basement membrane proteins were used to evaluate the effects of both chemicals on the basement membrane zone. Gross vesication was not seen. Pyknotic nuclei with or without dyskeratotic changes within epidermal keratinocytes were present at both doses. These changes varied more between skin specimens than they did between doses. Ballooning degeneration was more marked after SM exposures. Diffuse dermal-epidermal separation was present only at high-dose exposures and did not appear to correlate with the degree of changes locally in the overlying epidermis. Antibodies to laminin-5 showed decreased immunoreactivity after exposure to HN2 and SM. Immunoreactivity for laminin- was decreased to a lesser extent, and immunoreactivity for collagen IV and VII was unchanged. HN2 and SM produce similar histopathologic and immunohistochemical features after cutaneous exposure. These features suggest that part of mechanism of action of HN2 and SM is a direct effect on the basement membrane zone. Understanding the effects of HN2 and SM separate from their effect on DNA may be important in designing therapies and in advancing our understanding of the pathophysiologic changes induced by these chemicals when delivered topically.

Autoantigens↗
PubMed1998

Drug screening of patients who deliberately harm themselves admitted to the emergency department.

This study was a retrospective analysis of drugs present in blood and urine samples taken from patients (n = 200) admitted to the emergency department of a major teaching hospital with a provisional diagnosis of deliberate self-harm. The aim was to assess the current limited drug screening strategy to see whether it needed to be changed in any way. Drugs present in blood and urine were identified by immunoassay or chromatography, categorized, and concentration-toxicity effects evaluated when practicable. For each case, the various drugs/drug classes detected were correlated with those reported by the patient. A questionnaire evaluation of doctor's perceptions of the influence of the primary blood drug screen on patient destinations was administered. The rapid primary drug screen using a blood/plasma sample detected some 46% of all drugs identified. The doctors considered that it was influential in deciding on immediate patient destination, and therefore, it is likely to be a cost-effective measure. In addition, the screen detected toxic concentrations of drugs in a significant proportion of patients who did not report their ingestion correctly. A primary drug screen using a urine sample detected opiates, cannabinoids, and amphetamines but such detection was considered unlikely to alter short-term treatment. A high-performance liquid chromatography and gas chromatography-mass spectroscopy secondary screen using blood and urine detected a significant number of additional drugs, but was slow, costly, and not likely to alter short-term treatment. The authors conclude that the primary screen for alcohol, benzodiazepines, paracetamol, salicylate, and tricyclic antidepressants remains the optimal drug screening strategy. Quantitative or qualitative estimation of patient-reported drugs such as quinine, theophylline, verapamil, and antiepileptics may be justifiable in individual patients.

Adolescent↗
PubMed1997

Choice of treatment improves quality of life. A study on patients undergoing dialysis.

BACKGROUND: Quality of life (QOL) is an important measure of the success of medicine. Choice of treatment is an important variable influencing QOL. We studied QOL in patients undergoing treatment for end-stage renal failure. Until June 1993 our patients needing dialysis could freely choose continuous ambulatory peritoneal dialysis (CAPD); however, since that time most patients have been forced to undergo CAPD because the hemodialysis program is full. METHODS: We compared QOL in patients accepted before or after June 1993. Forty-five patients undergoing CAPD were studied during the period of choice compared with 44 who had no choice. Quality of life was studied by Bradburn Affect Scale, Mental Health Scale, Campbell Life Satisfaction, Perceived Health, Karnofsky Scale, Activity Scale, Physical Symptoms Scale, and desire for treatment change. RESULTS: The patients undergoing CAPD in the no-choice group had a lower score than the choice population in 4 of the 7 QOL scales. The Mental Health Scale mean score was 18.4 compared with 15.5, and the patients ranking highest on the Mental Health Scale decreased from 33% to 18%, while those ranking lowest increased 7-fold from 2% to 14% comparing choice with no-choice group. The Bradburn Affect Scale score was +0.7 in the choice group compared with -0.3 in the no-choice group. There were no differences in age, sex, race, or treatment that explained the difference. Influence of other time-related factors is unlikely as there were no similar lower scores with time in the QOL reported by patients in the in-center or assisted self-care hemodialysis or transplant groups. CONCLUSIONS: Once the freedom of choice of treatment is gone from the patients undergoing CAPD their psychological QOL deteriorates.

Adult↗
PubMed1997

Adenoviral-mediated gene transfer to murine small intestine is more efficient in neonates than adults.

PURPOSE: The authors sought to assess the feasibility of in vivo gene transfer to the small intestine using recombinant adenovirus in neonatal and adult mice. METHODS: H5.010CMVlacZ is a replication-defective, E1-deleted human type 5 adenovirus, which contains the lacZ gene under the control of a cytomegalovirus promoter and enhancer. The lacZ gene was used as a marker because its gene product, beta-galactosidase, is readily detected by X-gal histochemistry. Sixty neonatal (3 to 5 days old) and 45 adult (6 to 8 weeks old) C57BL/6 mice were investigated. Intestinal gene transfer was attempted with H5.010CMVlacZ by intraperitoneal (i.p.), intraluminal (IL), and intramural (i.m.) injection. Based on prior studies, the optimal dose of H5.010CMVlacZ was 1 x 10(8) plaque forming units (pfu/mL). Control animals received saline injections. Gene transfer on repeat administration of adenovirus has been shown to be prevented by neutralizing antibody. To determine if neonatal inoculation induced a humoral immune response, neonates (n = 5) that received i.p. injections were rechallenged with intravenous H5.010CMV alkphos, a similar adenoviral construct containing the alkaline phosphatase marker gene. Serum samples were analyzed by Western blot to detect the presence of adenoviral-specific antibody. RESULTS: Gene transfer to neonatal small intestine was successful by IL gastric (n = 8/10), IL jejunal (n = 9/10) and i.p. (n = 10/10) routes 2 days after injection. Macroscopic staining was present in 90% of standardized 2-cm small bowel segments. Transgene expression was identified in intestinal smooth muscle, serosa, and epithelium. Gene transfer to the adult small intestine was successful by IL jejunal (n = 4/5), i.m. (n = 5/5), and i.p. (n = 1/5) injection of adenoviruslacZ with focal staining (< 5% of 2-cm segments) in epithelium including crypts, muscle, and serosa. Three weeks after i.p. H5.010CMVlacZ in neonates, intravenous injection with H5.010CMValkphos resulted in hepatic transgene expression (n = 4/5) that was indistinguishable from a primary intravenous inoculation; persistent, lacZ expression was not detectable in the liver or intestine (n = 0/5). Western blot analysis detected adenoviral-specific antibodies after adult IM but not after neonatal i.p. injection. Furthermore, 3 weeks after neonatal i.p. injection repeat administration by the i.m. route was successful (n = 4/ 4). CONCLUSION: Gene transfer to neonatal and adult small intestine is feasible using recombinant adenovirus and is more efficient in neonates as indicated by increased surface area of marker gene expression, effectiveness of intraperitoneal delivery, and the ability to readminister recombinant adenovirus.

Adenoviruses, Human↗
PubMed1997

Heart health in rural Saskatchewan.

In Saskatchewan, as in the rest of Canada, cardiovascular disease (CVD) is the leading cause of death and hospitalization. Indeed, the rate of decline in mortality has been slower in Saskatchewan than in most other provinces. So when the federal-provincial Canadian Heart Health Initiative was established in 1986, the province set up the Saskatchewan Heart Health Program both to form part of the national initiative and to take advantage of the opportunities implicit in it.

Cardiovascular Diseases↗
PubMed1996

Making a difference.

Explore the source record for details and available documents.

Community Health Nursing↗
PubMed1995

Regulation and inhibition of collagenase expression by long-wavelength ultraviolet radiation in cultured human skin fibroblasts.

The cellular mechanisms responsible for the connective tissue changes produced by chronic exposure to UV light are poorly understood. Collagenase, a metalloproteinase, initiates degradation of types I and III collagen and thus plays a key role in the remodeling of dermal collagen. Collagenase synthesis by fibroblasts and keratinocytes involves the protein kinase C (PKC) second messenger system, and corticosteroids have been shown to suppress its synthesis at the level of gene transcription. Long-wavelength UV light (UVA, 320-400 nm) stimulates the synthesis of interstitial collagenase, as well as increasing PKC activity, in human skin fibroblasts in vitro. This study explores the regulation of collagenase expression by UVA in cultured human skin fibroblasts. Specifically, the time course, the effect of actinomycin D, an inhibitor of RNA synthesis, as well as the effect of PKC inhibitors and dexamethasone on expression of collagenase following UVA irradiation were examined. After UVA irradiation, collagenase mRNA rose rapidly between 4 and 12 h postirradiation, peaking 18 h post-UVA. Actinomycin D completely suppressed the UVA-induced increase in collagenase mRNA. Thus, new RNA synthesis is required for the UVA-induced increase in collagenase mRNA. The PKC inhibitor, H-7, blocked the increase in collagenase mRNA in response to UVA in a dose-dependent manner. Similarly, dexamethasone also inhibited collagenase gene expression induced by UVA in a dose-dependent fashion; the majority of the inhibitory effect was seen within the first 4 h after irradiation. These studies demonstrate that the effect of UVA on collagenase gene expression is regulated at the pretranscriptional level and may involve the PKC pathway.

Cells, Cultured↗
PubMed1995

Activation of guanylate cyclase in the guinea-pig trachea reduces contractile responses of the smooth muscle.

Guinea-pig tracheal strips were used to investigate whether activation of guanylate cyclase in the trachea can reduce the contractile responses of the smooth muscle. Guanylate cyclase was activated by glyceryl trinitrate and a combination of sodium nitrite and ascorbic acid. These activators inhibited tracheal smooth muscle contractions produced by acetylcholine, histamine and electrical field stimulation. However, in the presence of methylene blue, a guanylate cyclase inhibitor, tracheal smooth muscle contractions were not inhibited by the activators. But, in the presence of propranolol, which blocked inhibition mediated by beta-adrenoceptor, both glyceryl trinitrate and the sodium nitrite/ascorbic acid combination were still capable of inhibiting tracheal smooth muscle contractions. Additionally, methylene blue inhibited tracheal smooth muscle relaxation that was electrically induced. These results suggest that the inhibitory action mediated by activated guanylate cyclase may be a mechanism for regulating tracheal smooth muscle contractile responses.

Acetylcholine↗
PubMed1994

Identification of a multidrug resistance modulator with clinical potential by analysis of synergistic activity in vitro, toxicity in vivo and growth delay in a solid human tumour xenograft.

Circumvention of multidrug resistance in vitro by resistance modulators is well documented but their clinical use may be limited by effects on normal tissues. We have compared four resistance modifiers, both in terms of modulation of doxorubicin sensitivity in vitro and toxicity in vivo, in order to determine whether it is possible to select agents with clinical potential. Verapamil, D-verapamil and quinidine are all maximally active in the multidrug resistant cell line at about 7 microM and are not cytotoxic at this concentration. The tiapamil analogue Ro11-2933 is a highly potent resistance modulator such that at only 2 microM sensitization is greater than is seen with the other modulators at 7 microM. Since the ID50 concentration for Ro11-2933 is 17.7 microM (5-12-fold less than the other modifiers) we have used isobologram analysis to demonstrate that the interaction with doxorubicin is supra-additive and cannot be explained by additive toxicity. This method of analysis also revealed that when resistance modulation is related to the cytotoxicity of the modulator itself, all four modulators show comparable activity. On the other hand, measurement of the acute toxicity in mice of the modulators did reveal differences. The LD10 for verapamil (51 mg/kg) was about one third of that for quinidine (185 mg/kg) and this is consistent with the known maximum tolerated plasma levels in patients. Furthermore, whilst epirubicin alone was unable to reduce the growth rate of a multidrug resistant human tumour xenograft, the addition of quinidine, but not verapamil, at the maximum tolerated dose did do so. D-Verapamil was only about half as toxic as racemic verapamil and this too is consistent with clinical observations. The LD10 for Ro11-2933 (152 mg/kg) was comparable with that for quinidine. In the human tumour xenograft model maximal growth inhibition was observed with the combination of epirubicin and Ro11-2933 (45 mg/kg) and this degree of growth inhibition was comparable to that obtained with epirubicin alone in the drug sensitive xerografts. Ro11-2933 had no measurable effects on the plasma or tumour pharmacokinetics of epirubicin. These results suggest that it is possible to predict the clinical potential of a resistance modulator. Furthermore, Ro11-2933 is a promising agent for use in the clinic since maximal resistance modulation in vivo is observed at about one third of the LD10 dose.

Animals↗
PubMed1994

Interferon-stimulated response element and NF kappa B sites cooperate to regulate double-stranded RNA-induced transcription of the IP-10 gene.

To understand the mechanisms involved in dsRNA-induced gene expression, we analyzed the poly(I/C)-induced transcription of the IFN-inducible chemokine gene IP-10 using the GRE cell line in which type I IFN genes have been deleted. Accumulation of IP-10 mRNA in GRE cells was more strongly stimulated by treatment with dsRNA than by IFN-alpha or IFN-gamma and was independent of protein synthesis. This same pattern of response was produced when GRE cells were transiently transfected with a plasmid containing 243 bases of sequence from the promoter of the murine IP-10 gene linked to the chloramphenicol acetyltransferase reporter gene. Deletion- and site-specific mutagenesis of the 243 base pair fragment indicated that an ISRE located between residues -204 and -228 was a primary target site for the action of dsRNA on this promoter. This was confirmed by results showing that two copies of this ISRE tandemly arrayed in front of the thymidine kinase promoter were able to mediate reporter gene transcription in dsRNA-stimulated cells. At least one of the two NF kappa B binding sites present in the 243 base pair IP-10 promoter is also necessary for response to dsRNA; mutation of both sites eliminates promoter activity. Thus the ISRE and one NF kappa B site cooperate to produce transcriptional response to dsRNA.

Base Sequence↗
PubMed1994

Hypoxic induction of interleukin-8 gene expression in human endothelial cells.

Because leukocyte-mediated tissue damage is an important component of the pathologic picture in ischemia/reperfusion, we have sought mechanisms by which PMNs are directed into hypoxic tissue. Incubation of human endothelial cells (ECs) in hypoxia, PO2 approximately 14-18 Torr, led to time-dependent release of IL-8 antigen into the conditioned medium; this was accompanied by increased chemotactic activity for PMNs, blocked by antibody to IL-8. Production of IL-8 by hypoxic ECs occurred concomitantly with both increased levels of IL-8 mRNA, based on polymerase chain reaction analysis, and increased IL-8 transcription, based on nuclear run-on assays. Northern analysis of mRNA from hypoxic ECs also demonstrated increased levels of mRNA for macrophage chemotactic protein-1, another member of the chemokine superfamily of proinflammatory cytokines. IL-8 gene induction was associated with the presence of increased binding activity in nuclear extracts from hypoxic ECs for the NF-kB site. Studies with human umbilical vein segments exposed to hypoxia also demonstrated increased elaboration of IL-8 antigen compared with normoxic controls. In mice exposed to hypoxia (PO2 approximately 30-40 Torr), there was increased pulmonary leukostasis, as evidenced by increased myeloperoxidase activity in tissue homogenates. In parallel, increased levels of transcripts for IP-10, a murine homologue in the chemokine family related to IL-8, were observed in hypoxic lung tissue. Taken together, these data suggest that hypoxia constitutes a stimulus for leukocyte chemotaxis and tissue leukostasis.

Animals↗