PubMed Health⌕ Search

Biomedical subjects

F M Robertson

Publications and source records attributed to F M Robertson.

At least 19 recordsLinked to original sources
PubMed2002

Inhibition of ultraviolet light B-induced cutaneous inflammation by a specific cyclooxygenase-2 inhibitor.

Ultraviolet B (UVB) radiation is responsible for the majority of cutaneous damage following both acute and long-term exposure, and is believed to be the most important etiologic agent in human skin cancer. UVB carcinogenesis initially induces an inflammatory response characterized by edema, dermal infiltration of leukocytes, as well as the production and release of prostaglandins, which may be critical to the observed damaging effects of UVB light on skin. Recently, a specific cyclooxygenase-2 (COX-2) inhibitor, Celecoxib, was developed, which inhibits COX-2-induced inflammation without inhibiting the cytoprotective function of cyclooxygenase-1 (COX-1). Studies have demonstrated that oral administration of Celecoxib decreased the incidence of skin and colon tumors. Recently, the process of inflammation has been linked to tumor formation. The present study examined the effects of a topical application of Celecoxib on the acute UVB-induced cutaneous inflammatory response. We show that topical Celecoxib treatment effectively reduced many parameters of UVB-mediated inflammation, including edema, dermal myeloperoxidase activity, neutrophil infiltration, and prostaglandin E2 (PGE2) levels. By inhibiting this inflammatory response, topical Celecoxib treatment could ultimately be effective in preventing tumor development and progression in the skin, which is known to result from long-term UV exposure.

Animals↗
PubMed2001

Novel rapid method for visualization of extent and location of aerosol contamination during high-speed sorting of potentially biohazardous samples.

BACKGROUND: Containment of potentially biohazardous aerosols that result from high-speed sorting of human cells has been an increasingly important problem in analytical cytometry. The current method for assessing the efficiency of aerosol containment involves detection of aerosols containing sorted T4 bacteriophage on lawns of T4-susceptible Escherichia coli on plates that are placed in and around the sort area. Although this method is sensitive, it is time consuming and involves maintenance and handling of bacteria and sorting of bacteriophage that may themselves serve as sources of contamination for sorted viable human cells. METHODS: Glo Germ (5-microm melamine copolymer resin beads), which are fluorescent under black light illumination, were sorted on a Beckman-Coulter Elite ESP sorter in order to visualize deposition of aerosols under normal and mock failure modes. RESULTS: Glo Germ was successfully used under both normal sorting conditions, as well as mock failure mode, to visualize aerosol formation. CONCLUSIONS: We have developed a method to examine aerosol containment using modified Glo Germ, a product used for teaching aseptic technique in hospitals, industry, restaurants, and schools. Use of this technique represents a rapid, inexpensive, qualitative analysis of the extent and location of aerosol contamination from cell sorters.

Aerosols↗
PubMed2001

Mechanisms of nitric oxide-induced cytotoxicity in normal human hepatocytes.

Chronic exposure of hepatocytes to reactive nitrogen species (RNS) following liver injury and inflammation leads not only to functional and morphological alterations in the liver but also to degenerative liver diseases and hepatocellular carcinoma. Previously, we showed that S-nitroso-N-acetylpenicillamine-amine (SNAP), which generates nitric oxide, and 3-morpholinosydnonimine (Sin-1), which generates equal molar concentrations of superoxide and nitric oxide resulting in peroxynitrite production, exhibited different levels of cytotoxicity to normal human hepatocytes in culture. The aim of the present study was to elucidate some of the molecular and cellular pathways leading to hepatocyte cell death induced by RNS. Following treatment of the hepatocytes with SNAP or Sin-1, gene-specific DNA damage was measured in mtDNA and a hprt gene fragment using a quantitative Southern blot analysis. Both agents induced dose-dependent increases in DNA damage that was alkaline labile, but not sensitive to both formamidopyrimidine-DNA glycosylase (fpg) and endonuclease III, which recognize 8-oxoguanine, thymine glycol, and other oxidized pyrimidines. DNA damage was two- to fivefold greater in mtDNA than in the hprt gene fragment. There was a persistent and marked increase in DNA damage posttreatment that appeared to arise from the disruption of electron transport in the mitochondria, generating reactive species that saturated the repair system. DNA damage induced by Sin-1 and SNAP led to cell-cycle arrest in the S-phase, growth inhibition, and apoptosis. The data support the hypothesis that the functional and morphological changes observed in liver following chronic exposure to RNS are, in part, the result of persistent mitochondrial and nuclear DNA damage.

Adult↗
PubMed2001

Protection of human keratinocyte mtDNA by low-level nitric oxide.

This study was designed to evaluate the DNA damaging effects of nitric oxide and to determine whether the endogenous generation of nitric oxide at low levels in the cell exerts a protective effect against this damage. Damage to mitochondrial and nuclear DNA in normal human epidermal keratinocytes (NHEK) was assessed after treatment of these cells with varying concentrations of S-nitroso-N-acetylpenicillamine, which decomposes to release nitric oxide. The results showed that mitochondrial DNA was more vulnerable to nitric oxide-induced damage than was a similarly sized fragment of the beta-globin gene. To evaluate the effects on DNA damage by pretreatment of cells with low-levels of nitric oxide, NHEK cells were treated with the prodrug V-PYRRO/NO. This agent is metabolized inside these cells and releases small quantities of nitric oxide. The cells then were exposed to damaging amounts of nitric oxide produced by S-nitroso-N-acetylpenicillamine. The results of these studies showed that pretreatment of NHEK cells with V-PYRRO/NO attenuated the mtDNA damage and loss of cell viability produced by exposure to S-nitroso-N-acetylpenicillamine.

Base Sequence↗
PubMed2001

Inhibition of cutaneous UV light-induced tumor necrosis factor-alpha protein production by Allotrap 1258, a novel immunomodulatory peptide.

Peptides derived from the heavy chain of the HLA Class-I molecules have been shown to modulate immune responses both in vivo and in vitro. Using a computer-aided rational drug design approach, novel immunomodulatory peptides were designed based on peptide 2702.75-85, derived from HLA-B2702. Several peptides were identified which had increased immunomodulatory activity, including peptides RDP1258 and its D-isomer the peptide Allotrap 1258. The present study using Skh/hr hairless mouse skin model evaluated the in vivo effects of Allotrap 1258 on acute UVB-induced skin inflammation. Here we demonstrate that intraperitoneal administration of Allotrap 1258 1 h prior to UV exposure resulted in significantly diminished levels of UV-induced tumor necrosis factor (TNF)-alpha protein production in the epidermis but had no effect on other parameters of the acute UV-induced inflammatory response. By virtue of its ability to suppress TNF-alpha protein production, Allotrap 1258 could prove to be an effective modulator of inflammatory responses.

Adjuvants, Immunologic↗
PubMed2000

Laparoscopic nephrectomy in children.

BACKGROUND: Laparoscopic nephrectomy in the adult population is reported with increased frequency. We present our initial experience with laparoscopic nephrectomy in children. METHODS: Over a 2-year period, 11 nephrectomies were performed in nine children aged 16 months to 16 years (mean, 6.5 years). All patients were referred due to complications of a nonfunctioning kidney. Seven patients had recurrent urinary tract infections, and two had refractory hypertension. Two patients underwent bilateral laparoscopic nephrectomy. The operation was performed using four access ports measuring 3.5 to 10 mm. RESULTS: All kidneys were removed successfully using a laparoscopic technique. The average length of the operation was 163 min per kidney (range, 90-420). The estimated blood loss was <10-150 ml (mean, 45). No patient required transfusion. Seven patients were discharged home by postoperative day 2. The two patients with the longest operating times were discharged home on postoperative days 4 and 5 due to delay in return of bowel function. Narcotic use was minimal, and all patients enjoyed a rapid return to full activity. CONCLUSION: Laparoscopic nephrectomy is a viable alternative to open nephrectomy in children. Further experience with this technique is required to establish its efficacy and reduce the operating time

Adolescent↗
PubMed1999

Correlation of aromatase and cyclooxygenase gene expression in human breast cancer specimens.

Aromatase, the enzyme system catalyzing estrogen biosynthesis, is found in stromal tissue in the breast. The increased expression of the aromatase CYP19 gene in breast cancer tissues was recently associated with a promoter region regulated through cAMP-mediated pathways. PGE2, derived from cyclooxygenase, increases intracellular cAMP levels and stimulates estrogen biosynthesis. This association suggest that local production of PGE2 via cyclooxgenase isozymes may influence estrogen biosynthesis. The present study represents the first to examine the levels of mRNA expression of CYP19, COX-1, and COX-2 genes in human breast cancer specimens and normal breast tissue samples using semi-quantitative RT-PCR methods. Positive correlations were observed between CYP19 and COX-2 and the greater extent of breast cancer cellularity. Linear regression analysis using a bivariate model shows a strong linear association between CYP19 expression and the sum of COX-1 and COX-2 expression. This significant relationship between the aromatase and cyclooxygenase enzyme systems suggests that autocrine and paracrine mechanisms may be involved in hormone-dependent breast cancer development via growth stimulation from local estrogen biosynthesis.

Aromatase↗
PubMed1999

Genetic induction and upregulation of cyclooxygenase (COX) and aromatase (CYP19): an extension of the dietary fat hypothesis of breast cancer.

A novel model of mammary carcinogenesis is proposed involving sequential induction and upregulation of cyclooxygenase and aromatase genes by essential fatty acids prominent in the US diet. The basic carcinogenic processes are: (1) constitutive prostaglandin biosynthesis and formation of mutagenic oxygen and nitrogen free radicals responsible for tumor initiation; (2) PGE-2-induced expression of aromatase and constitutive estrogen biosynthesis which sustains mitogenesis and tumor promotion; and (3) PGE-2-induced expression of vascular endothelial growth factor which stimulates angiogenesis and tumor metastasis.

Aromatase↗
PubMed1998

Comparative expression of novel vascular endothelial growth factor/vascular permeability factor transcripts in skin, papillomas, and carcinomas of v-Ha-ras Tg.AC transgenic mice and FVB/N mice.

One of the most frequently detected changes in human solid tumors is the mutation of the ras oncogene, which has been associated with production of angiogenic growth factors such as vascular endothelial growth factor/vascular permeability factor (VEGF/VPF). Using the v-Ha-ras Tg-AC transgenic mice and the background FVB/N strain of inbred mice, the pattern of expression of specific VEGF/VPF transcripts was characterized in major organs and in skin, papillomas, and carcinomas during multi-stage skin carcinogenesis. Three VEGF/VPF transcripts were found to be constitutively expressed in skin as well as the major organs in both mouse strains, which corresponded in size and sequence to previously reported murine VEGF120 with a bp size of 331, VEGF164 with a bp size of 333, and VEGF188 with a bp size of 407. A previously unreported fourth murine transcript was also detected in skin and major tissues from both mouse strains which corresponded to rat VEGF144, with a bp size of 404. In addition, a unique 425 bp VEGF transcript which corresponded to human VEGF205 was present in highly vascularized tissues including heart, lung, liver, kidney, brain, as well in papillomas and carcinomas isolated from v-Ha-ras Tg.AC mice. In contrast, VEGF205 was present only in carcinomas derived from FVB/N mice. An antibody generated from a peptide sequence designed to detect each of the five VEGF/VPF peptides defined by RT-PCR analysis confirmed the existence of these five peptides and confirmed that the murine VEGF205 peptide was selectively expressed in papillomas and carcinomas derived from v-Ha-ras Tg.AC mice. These results demonstrate that there is significant alternative splicing of the murine VEGF/VPF gene during multi-stage carcinogenesis, which results in four commonly expressed VEGF transcripts. In addition, these studies identified a fifth VEGF transcript and peptide at the later stages of tumor promotion and in progression which appears to be linked to the presence of v-Ha-ras.

Alternative Splicing↗
PubMed1998

Ibuprofen-induced inhibition of cyclooxygenase isoform gene expression and regression of rat mammary carcinomas.

A single dose of 75 mg/kg 7,12 dimethylbenz[a]anthracene was administered to 50-day-old virgin female Sprague-Dawley rats and 100 days later, animals were randomized and provided with Teklad rodent chow mixed with a dose of 25 mg/rat/day ibuprofen for 35 days. Ibuprofen treatment reduced tumor volume (P < 0.05) and significantly inhibited gene expression of both cyclooxygenase- and cyclooxygenase-2 (P < 0.02). These results indicate that ibuprofen induced significant regression of established mammary carcinomas which was associated with inhibition of expression of isoforms of the gene responsible for prostaglandin production.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1998

Beta2 integrin/ICAM-1 adhesion molecule interactions in cutaneous inflammation and tumor promotion.

The beta2 integrin (CD 18/CD 11 a, b, c) family of proteins mediate adherence of leukocytes to vascular endothelium and the associated ligand, intercellular adhesion molecule-1 (ICAM-1; CD 54), interacts with beta2 integrin proteins to allow transendothelial migration of leukocytes into sites of inflammation. The present study examines the function of these proteins in a murine model of acute cutaneous inflammation induced following topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA) to the dorsal epidermis of SENCAR mice and in a model of skin multistage carcinogenesis. At 24 h following topical application of TPA to the dorsal epidermis of mice, dermal leukocytes expressed higher levels of beta2 integrin protein compared with the lower levels of beta2 integrin protein expression by peripheral blood leukocytes. ICAM-1 protein was localized to epidermal keratinocytes and vascular endothelium in TPA-treated skin and to proliferating papilloma cells. Intravenous (i.v.) injection of either 50 microg anti-beta2 integrin antibody alone or in combination with anti-ICAM-1 antibody significantly inhibited both TPA-stimulated neutrophil infiltration into the dermis (P < 0.001) and myeloperoxidase (MPO) activity (P < 0.03 anti-beta2 integrin antibody; P < 0.01 anti-beta2 integrin + ICAM-1 adhesion molecule antibodies), but had no effect on TPA-induced epidermal hyperplasia. In addition, injection of either anti-ICAM-1 adhesion molecule antibody alone (P < 0.004) or in combination with anti-beta2 integrin antibody (P < 0.001) significantly inhibited TPA-induced production of 7,8-dihydroxy-2'-deoxyguanosine (8-OHdG) immunoreactive proteins by epidermal keratinocytes. Beta2 integrin/ICAM-1 adhesion molecules work in concert to regulate migration, retention and functional activation of leukocytes within the dermis during TPA-induced skin inflammation and within stromal tissue of papillomas that form during multi-stage carcinogenesis. Agents that inhibit these receptor/ligand interactions may be useful in defining the roles of specific cell populations in cutaneous inflammation and multistage carcinogenesis and may also have potential as anti-promoting and anti-progression agents.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1998

Inhibitory effects of pentoxifylline on ultraviolet B light-induced cutaneous inflammation.

It is now recognized that ultraviolet (UV) radiation is a potent environmental insult capable of interfering with immunity to skin cancers and modifying certain immunologic reactions within both locally irradiated skin and distant, unexposed sites. Exposure to UVB light (290-320 nm) induces a potent cutaneous inflammatory response that involves the infiltration of leukocytes into the dermis as well as the production of proinflammatory cytokines by both resident epidermal keratinocytes and dermal cells. Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine that has been shown to be a major mediator of UVB light effects on cutaneous immunity. Recent studies have demonstrated that pentoxifylline (PTX), a xanthine-derived phosphodiesterase inhibitor, has the ability to inhibit synthesis of TNF-alpha. To examine the effects of PTX on UVB-mediated cutaneous inflammation, Skh/hr hairless mice were injected intraperitoneally with either phosphate-buffered saline or 50 microg/g PTX 1 h before exposure to 2240 J/m2 UVB. Reverse transcription-polymerase chain reaction and immunohistochemical techniques were used to demonstrate that 24 h to 1 wk after UVB-light irradiation, PTX inhibited UVB-induced TNF-alpha gene expression, inhibited the increase in epidermal TNF-alpha protein synthesis, blocked the increase in epidermal proliferation observed after exposure to UVB light, and decreased production of myeloperoxidase by neutrophils infiltrating into the dermis. These studies demonstrated that PTX modifies epidermal responses after acute UVB light exposure and suggest that PTX treatment may be used clinically to modulate the deleterious effects of long-term UVB-light irradiation.

Animals↗
PubMed1997

Sensitivity of human hepatocytes in culture to reactive nitrogen intermediates.

The cytotoxic effects of 3-morpholinosydnonimine (Sin-1) and S-nitroso-N-acetylpenicillamine-amine (SNAP) on replicatively active human hepatocyte cells in culture was determined as a function of oxidant type. Both Sin-1 which yields nitric oxide and peroxynitrite following the generation of superoxide anion plus nitric oxide, and SNAP which generates nitric oxide, induced dose dependent decreases in the colony forming capabilities of the human hepatocytes. Sin-1 was much more cytotoxic (LD50 = 400 microM) than SNAP (LD50 = 1250 microM). Comparatively, both compounds were much less cytotoxic than H2O2 (LD50 = 96 microM). Sin-1 induced 4-fold higher levels of cellular nitrite than that generated by the chemical in cell free medium. Nitrotyrosine, a marker of peroxynitrite formation in cells, was immunohistochemically detected in hepatocytes treated with both Sin-1 and SNAP. The formation of 3-nitrotyrosine by hepatocytes incubated with SNAP, suggests that hepatocytes generate intracellular superoxide which reacts with the exogenous nitric oxide derived from SNAP to produce intracellular peroxynitrite, resulting in the SNAP cytotoxicity. The enhanced levels of Sin-1 cytotoxicity on the hepatocytes is suggested to be due both to the chemical generation of peroxynitrite and superoxide anion by Sin-1. These data indicate that peroxynitrite is formed in cultured human hepatocytes inhibiting their replication, and that peroxynitirite may play a significant role in the pathogenesis of liver disease.

Cells, Cultured↗
PubMed1996

Mutagenic potential of peripheral blood leukocytes: in vivo exposure to the carcinogen 7,12-dimethylbenz[a]anthracene, and the tumor promoter 12-O-tetradecanoylphorbol acetate followed by in vitro co-culture with AS52 cells.

Co-culture of AS52 cells with peripheral blood leukocytes (PBLs), obtained from SENCAR mice topically treated with either tetradecanoyl-phorbol-13-acetate (TPA) or 7,12-dimethylbenz[a]anthracene (DMBA)-TPA, resulted in a 7-160-fold increase in the mutation frequency of the gpt gene in AS52 cells when compared to that induced by PBLs isolated from mice treated with either acetone or DMBA. This increase in mutation frequency was inhibited by the anti-oxidant (-)epigallocatechin gallate (EGCG). These results demonstrate that the AS52 cell line can be used as a mammalian mutagenesis model for the study of in vivo mechanism(s) of mutagenesis by leukocytes and also as a model for in vivo chemoprevention studies.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1996

Alterations in transforming growth factor-alpha and epidermal growth factor receptor expression during rat esophageal tumorigenesis.

Transforming growth factor-alpha (TGF-alpha) stimulates cell proliferation through interaction with its receptor, the epidermal growth factor receptor (EGFR), by activating its tyrosine kinase activities. The simultaneous overexpression of TGF-alpha and EGFR by tumor cells is thought to trigger the autocrine growth pathway, leading to uncontrolled proliferation. To examine their roles in rat esophageal tumorigenesis induced by the chemical carcinogen N-nitrosomethylbenzylamine (NMBA), TGF-alpha, and EGFR expression was evaluated in normal rat esophageal epithelium, in NMBA-induced preneoplastic lesions, and in papillomas by quantitative reverse transcription-polymerase chain reaction (RT-PCR), in situ hybridization, and immunohistochemical analyses. Compared with the levels in normal epithelium, the TGF-alpha and EGFR mRNA levels in esophageal papillomas were 3.6 and 1.9 times higher, respectively. In the preneoplastic epithelium, although a trend of increased TGF-alpha and EGFR mRNA levels was observed, collectively there were no significant differences between preneoplastic and normal samples by RT-PCR analysis. In situ hybridization and immunohistochemical staining showed increased levels of TGF-alpha and EGFR mRNA and protein products in papillomas and in pronounced hyperplastic and dysplastic lesions. TGF-alpha and EGFR expression correlated with each other and with the expression of proliferating cell nuclear antigen, a marker for cell proliferation. These results suggest that disregulation of TGF-alpha and EGFR expression may contribute to autonomous cell growth and may play an important role in rat esophageal tumorigenesis induced by NMBA.

Animals↗
PubMed1996

Transanastomotic feeding tubes in repair of esophageal atresia.

To avoid the need for a gastrostomy and parenteral nutrition during the 7- to 10-day healing period after esophageal anastomosis, the authors modified their technique for esophageal atresia repair to include placement of a transanastomotic feeding tube. A SILASTIC transanastomotic feeding tube and early enteral nutrition was used for 19 of 23 consecutively treated patients after repair of esophageal atresia and tracheoesophageal fistula. One of the 19 patients had recurrent fistula and another had an anastomotic leak. Five patients had significant gastroesophageal reflux (noted on barium esophagram), and four had strictures that required dilatation. Parenteral nutrition was necessary for only two patients. The authors conclude that transanastomotic feeding tubes and early enteral nutrition are safe and effective, reduce costs, and do not appear to increase the incidence of anastomotic leaks, strictures, or gastroesophageal reflux.

Catheters, Indwelling↗
PubMed1996

Recurrence of immune thrombocytopenic purpura after splenectomy.

Immune thrombocytopenic purpura (ITP) frequently leads to splenectomy. Accessory spleens maybe found in a variety of locations, and may not be readily apparent. Retained accessory splenic tissue can lead to recurrent ITP, which, this report (involving multiple relapses in a single patient) demonstrates.

Adolescent↗