Biomedical subjects

Rodney J Scott

Publications and source records attributed to Rodney J Scott.

34 records · Page 2Linked to original sources

PubMed2005

Cytokine responses and sudden infant death syndrome: genetic, developmental, and environmental risk factors.

Despite the success of the campaigns to reduce the risk of sudden infant death syndrome (SIDS), it still remains the major cause of postneonatal mortality. The incidence of SIDS is higher among ethnic groups in which there are also high incidences of serious infectious diseases. The risk factors for SIDS parallel those for susceptibility to infection, and recent data have provided evidence to support the mathematical model of the common bacterial toxin hypothesis. One current hypothesis for the etiology of SIDS is that the deaths are a result of overwhelming proinflammatory responses to bacterial toxins; as in inflammatory responses to sepsis, cytokines, induced by bacterial toxins, cause physiological changes leading to death. The genetic, developmental, and environmental risk factors for SIDS are reviewed in relation to colonization by potentially harmful bacteria and the inflammatory responses induced in the nonimmune infant to microorganisms or their products.

Bacterial Infections↗

PubMed2005

Mutation analysis of the MYH gene in an Australian series of colorectal polyposis patients with or without germline APC mutations.

The MYH gene has recently been shown to be associated with a recessive form of colorectal adenomatous polyposis. Two common mutations in the MYH gene have been identified that lend themselves to rapid screening. We have examined a series of 302 individuals comprising 120 control subjects, 120 patients diagnosed with adenomatous polyposis but without germline mutations in the APC gene and 62 patients diagnosed with familial adenomatous polyposis all harbouring confirmed causative APC germline mutations. The results reveal that MYH accounts for 16 percent of polyposis patients without germline mutations in the APC gene and that it does not appear to be a modifier gene in FAP patients diagnosed with APC germline mutations.

Adenomatous Polyposis Coli↗

PubMed2005

Differential proteolytic enzyme activity in eosinophilic and neutrophilic asthma.

RATIONALE: Asthma is characterized by both chronic inflammation and remodeling of the airways. Proteases are important mediators of inflammation, cytokine activation, and tissue remodeling. OBJECTIVES: This study investigated matrix metalloproteinase-9 (MMP-9) and neutrophil elastase (NE) enzyme activity in the sputum of subjects with different inflammatory phenotypes of asthma (eosinophilic, neutrophilic, and paucigranulocytic asthma) and in healthy control subjects. METHODS AND MEASUREMENTS: Nonsmoking adults with asthma and healthy control subjects underwent hypertonic saline challenge and sputum induction. Selected sputum portions were dispersed with dithiothreitol and assayed for MMP-9 and NE enzyme activity. MAIN RESULTS: Subjects with eosinophilic asthma had significantly more active MMP-9 (39 ng/ml) compared with those with neutrophilic asthma (10 ng/ml) and control subjects (2.5 ng/ml, p < 0.01). Although there were high levels of total MMP-9 in neutrophilic asthma (5,273 ng/ml), most (> 99%) was inactivated (and bound to tissue inhibitor of metalloproteinase-1). In neutrophilic asthma, more subjects had NE activity (39%) compared with both healthy control subjects (0%), subjects with eosinophilic asthma (6%), or subjects with paucigranulocytic asthma (0%, p < 0.05). There were strong and consistent positive correlations between interleukin-8, neutrophils, and proteolytic enzymes. MMP-9 was inversely correlated with NE (r = -0.93). CONCLUSIONS: Proteolytic enzyme activity in asthma is dependent on the underlying inflammatory phenotype and is differentially regulated with MMP-9 activity a feature of eosinophilic inflammation, and active NE in neutrophilic inflammation.

Adolescent↗

PubMed2005

Comparison of genomic abnormalities between BRCAX and sporadic breast cancers studied by comparative genomic hybridization.

Very little is known about the chromosomal regions harbouring genes involved in initiation and progression of BRCAX-associated breast cancers. We applied comparative genomic hybridization (CGH) to identify the most frequent genomic imbalances in 18 BRCAX hereditary breast cancers and compared them to chromosomal aberrations detected in a group of 27 sporadic breast cancers. The aberrations observed most frequently in BRCAX tumours were gains of 8q (83%), 19q (67%), 19p (61%), 20q (61%), 1q (56%), 17q (56%) and losses of 8p (56%), 11q (44%) and 13q (33%). The sporadic cases most frequently showed gains of 1q (67%), 8q (48%), 17q (37%), 16p (33%), 19q (33%) and losses of 11q (26%), 8p (22%) and 16q (19%). Losses of 8p and gains 8q, 19 as well as gains of 20q (with respect to ductal tumours only) were detected significantly more often in BRCAX than in sporadic breast cancers. Analysis of 8p-losses and 8q-gains showed that these aberrations are early events in the tumorigenesis of BRCAX tumors. The findings of this report indicate similarities between BRCAX and BRCA2 tumours, possibly suggesting a common pathway of disease. These findings need confirmation by more extensive studies because only a limited number of cases were analysed and there are relatively few reports published.

Adult↗

PubMed2005

CDKN2A common variants and their association with melanoma risk: a population-based study.

The population frequencies of the CDKN2A variants remain undetermined. In Poland there are three common variants of CDKN2A: an alanine to threonine substitution (A148T), Nt500c>g and Nt540c>t, which have been detected in other populations. To establish if they are associated with an increased malignant melanoma (MM) risk we did an association study based on genotyping 471 patients with MM and 1,210 random control subjects from the same Polish population. We found a significantly increased frequency of the A148T variant among patients with MM (7.0%) in comparison with the general population (2.9%). The incidence of the A148T variant remained greater in both unselected and familial melanoma subgroups. A statistically significant positive association was seen for unselected MM (odds ratio, 2.529; P = 0.0003), especially in patients diagnosed under 50 years of age (odds ratio, 3.4; P = 0.0002). The A148T carrier population (heterozygous G/A alleles) was more likely to have a relative with malignancy compared with the noncarrier population (57% versus 36%, respectively; P = 0.03). Further examination of the CDKN2A promoter sequence done in 20 melanoma patients with the A148T change (heterozygous G/A alleles) and 20 patients with MM without this alteration identified it was in linkage disequilibrium with a polymorphism in the promoter region at position P-493. We found no statistically significant overrepresentation of the Nt500c>g and the Nt540c>t polymorphisms in the Polish melanoma population. In conclusion, the A148T variant of the CDKN2A gene seems to be associated with an increased risk of development of MM. Additional studies are required to confirm whether this particular change is associated with increased risk of other nonmelanoma malignancies.

Adult↗

PubMed2004

Interleukin 1-beta responses to bacterial toxins and sudden infant death syndrome.

We tested the hypothesis that significantly higher IL-1beta responses to toxic shock syndrome toxin (TSST) noted for parents of sudden infant death syndrome (SIDS) infants might be due in part to genetic factors such as the IL-1beta (C-511T) and IL-1RN (T+2018C) single nucleotide polymorphisms (SNP). The first objective was to assess the distribution of these polymorphisms among SIDS infants, parents of SIDS infants and controls, and two ethnic groups: Aboriginal Australians who have a high incidence of SIDS; and Bangladeshis who in Britain have a low incidence of SIDS compared with Europeans. The second objective was to assess IL-1beta responses to endotoxin and toxic shock syndrome toxin (TSST) from leukocytes of smokers and non-smokers in relation to these polymorphisms. There were major differences in the distributions of the IL-1beta (C-511T) SNP between Europeans and Bangladeshis (p=0.00) and between Europeans and Aboriginal Australians (p=0.00); however, they were similar for the Bangladeshi and Aboriginal Australian subjects. The allele frequency distribution of the IL-1RN (T+2018C) SNP for the Aboriginal Australians was statistically different from the European group (p=0.00), but it was not different from the Bangladeshi group (p=0.09). Compared with controls of European origin, there were no significant differences in the distribution of these polymorphisms among SIDS infants or parents of SIDS infants. For the IL-1beta (C-511T) SNP, the highest IL-1beta responses to endotoxin were obtained with leukocytes of non-smokers with the heterozygous CT genotype. Smokers had significantly lower levels of IL-1beta in response to endotoxin (p=0.01) and these differences were significant for donors with the wild type CC (p=0.00) and CT (p=0.03) genotypes. Similar patterns were observed for IL-1beta responses to TSST, but the differences were not significant. For the IL-1RN (T+2018C) SNP, the highest IL-1beta responses to endotoxin were obtained with leukocytes from non-smoker donors with the wildtype TT genotype and significantly lower responses were found with leukocytes from donors with the TC genotype (p=0.02). The responses of smokers were lower but the differences were significant only for donors with the TT genotype (p=0.00). Similar patterns were observed for IL-1beta responses to TSST, but the differences were not significant. IL-1beta responses to both endotoxin and TSST were increased for the small number of smokers with the TT genotype of the IL-1beta (C-511T) SNP. The TT genotype of the IL-1beta (C-511T) was found predominantly among Aboriginal Australian and Bangladeshi individuals but only a small proportion of Europeans. Smokers with the AA genotype of the IL-10 (G-1082A) SNP which is found predominantly among these two groups had significantly lower levels of IL-10 responses. If cigarette smoke enhances pro-inflammatory responses and reduces anti-inflammatory responses in individuals with these genotypes, this might partly explain the increased susceptibility of Aboriginal Australian infants to infections and SIDS.

Bacterial Toxins↗

PubMed2004

Ethnicity, infection and sudden infant death syndrome.

Epidemiological studies found the incidence of SIDS among Indigenous groups such as Aboriginal Australians, New Zealand Maoris and Native Americans were significantly higher than those for non-Indigenous groups within the same countries. Among other groups such as Asian families in Britain, the incidence of SIDS has been lower than among groups of European origin. Cultural and childrearing practices as well as socio-economic factors have been proposed to explain the greater risk of SIDS among Indigenous peoples; however, there are no definitive data to account for the differences observed. We addressed the differences among ethnic groups in relation to susceptibility to infection because there is evidence from studies of populations of European origin that infectious agents, particularly toxigenic bacteria might trigger the events leading to SIDS. The risk factors for SIDS parallel those for susceptibility to infections in infants, particularly respiratory tract infections which are also major health problems among Indigenous groups. Many of the risk factors identified in epidemiological studies of SIDS could affect three stages in the infectious process: (1) frequency or density of colonisation by the toxigenic species implicated in SIDS; (2) induction of temperature-sensitive toxins; (3) modulation of the inflammatory responses to infection or toxins. In this review we compare genetic, developmental and environmental risk factors for SIDS in ethnic groups with different incidences of SIDS: low (Asians in Britain); moderate (European/Caucasian); high (Aboriginal Australian). Our findings indicate: (1) the major difference was high levels of exposure to cigarette smoke among infants in the high risk groups; (2) cigarette smoke significantly reduced the anti-inflammatory cytokine interleukin-10 responses which control pro-inflammatory responses implicated in SIDS; (3) the most significant effect of cigarette smoke on reduction of IL-10 responses was observed for donors with a single nucleotide polymorphism for the IL-10 gene that is predominant among both Asian and Aboriginal populations. If genetic makeup were a major factor for susceptibility to SIDS, the incidence of these deaths should be similar for both populations. They are, however, significantly different and most likely reflect differences in maternal smoking which could affect frequency and density of colonisation of infants by potentially pathogenic bacteria and induction and control of inflammatory responses.

Humans↗

PubMed2004

Interleukin-10 and sudden infant death syndrome.

Uncontrolled pro-inflammatory responses to infections or bacterial toxins have been suggested to play a role in triggering the physiological events leading to sudden infant death syndrome (SIDS). We tested the hypothesis that these uncontrolled responses might be due to interactions between the gene polymorphisms inducing low levels of IL-10 and exposure to cigarette smoke. In vitro, the IL-10 (G-1082A) polymorphism was associated with low IL-10 levels and the -1082G allele was associated with high levels. The first objective was to assess the distribution of this polymorphism among SIDS infants, parents of SIDS infants and controls, and two ethnic groups: Aboriginal Australians who have a high incidence of SIDS; and Bangladeshis who in Britain have a low incidence of SIDS compared with Europeans. The second objective was to assess effects of human recombinant IL-10 on interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) responses of human leukocytes to staphylococcal toxins implicated in SIDS. The third objective was to assess IL-10 responses to endotoxin and toxic shock syndrome toxin (TSST) from leukocytes of smokers and non-smokers in relation to the IL-10 (G-1082A) polymorphism. There were major differences in the distributions of these polymorphisms between Europeans and Bangladeshis (p=0.00) and between Europeans and Aboriginal Australians (p=0.00); however, they were similar for the Bangladeshi and Aboriginal Australian subjects. There were no significant differences in the distribution of these polymorphisms among SIDS infants or parents of SIDS infants compared to control groups. IL-10 significantly reduced IL-6 and TNF-alpha responses to TSST and staphylococcal enterotoxins A and C. At 50 ng ml(-1), IL-10 significantly increased TNF-alpha but not IL-6 responses to TSST and enterotoxin A. Although IL-10 responses to endotoxin were lower from leukocytes of smokers who were homozygous for the G allele, the differences were not significant; however, significantly lower IL-10 responses were found for smokers who were homozygous for the A allele (p=0.01) and heterozygotes (p=0.04). The pooled data found smokers had significantly lower levels of IL-10 responses to TSST, but there were no significant differences for smokers compared with non-smokers for the three genotypes. The high incidence of SIDS and serious respiratory infections among Aboriginal Australian infants and the low incidence of these conditions among Bangladeshi infants might be explained in part by our findings of differences in IL-10 responses between smokers and non-smokers. The lowest levels of IL-10 responses were observed among smokers who were homozygous for the A allele which is most prevalent among the Aboriginal Australians (83%) and Bangladeshis (84%). The major difference between the risk factors for SIDS in these two groups is the level of exposure of infants to cigarette smoke associated with maternal smoking.

Adult↗

PubMed2004

Germline mutation and large deletion analysis of the CDKN2A and ARF genes in families with multiple melanoma or an aggregation of malignant melanoma and breast cancer.

The CDKN2A/ARF genes have been associated with increased risk of malignant melanoma (MM) in families with multiple members affected by disease and in families characterized by the constellation of breast cancer and MM. The exact contribution of CDKN2A/ARF to disease risk remains poorly characterized, especially in diverse populations. In this report, the contribution of CDKN2A/ARF germline mutations and large rearrangements to disease in Polish familial MM (FMM) and aggregations of breast cancer and MM were assessed using a strategy that included genomic sequencing, restriction fragment length polymorphism and multiplex ligation-dependent probe amplification. We examined 16 FMM cases (group 1), 44 MM probands with a cancer family aggregation (CFA) that included at least one breast cancer (group 2) and 22 breast cancer probands with CFA and MM (group 3). The results revealed a paucity of mutations in CDKN2A/ARF, suggesting that in the Polish population this gene does not contribute significantly to either FMM or MM within the context of CFA.

Adult↗

PubMed2004

The NOD2 3020insC mutation and the risk of colorectal cancer.

Several predispositions to colorectal cancer have been identified, but little is known about genetic susceptibilities to disease in older persons. Colorectal cancer is a risk in Crohn's disease and is believed to be associated with an inappropriate inflammatory response. Recently, the NOD2 gene has been associated with Crohn's disease, which further strengthens the notion that the inflammatory response plays a crucial role in this disease. Several mutations have been identified in the NOD2 gene, which appear with significantly higher frequency in patients with the disease. One such mutation (3020insC) is believed to be clearly causative because it results in a prematurely truncated protein with a predicted reduction in functional efficiency. In this report, we have examined the frequency of the 3020insC mutation in a series of 856 individuals including 556 patients with colorectal cancer. The frequency of the 3020insC mutation in a consecutive series of 250 non-hereditary nonpolyposis colorectal cancer patients >50 years of age was significantly elevated compared with the control population (odds ratio, 2.23; P = 0.0046). The results indicate that NOD2 may be a predisposing factor to colorectal cancer characterized by an older average age of disease onset in persons who do not harbor any other genetic predisposition to disease.

Adult↗

PubMed2004

Relative frequency and morphology of cancers in STK11 mutation carriers.

BACKGROUND & AIMS: There is limited data on the spectrum and risk for cancer associated with germline serine/threonine protein kinase 11 (STK11) mutations that cause Peutz-Jeghers syndrome (PJS). METHODS: We analyzed the incidence of cancer in 240 individuals with PJS possessing germline mutations in STK11. RESULTS: Fifty-four cancers were found among carriers. Overall, the risk for developing cancer at ages 20, 30, 40, 50, 60, and 70 years was 1%, 3%, 19%, 32%, 63%, and 81%, respectively. Kaplan-Meier analysis showed similar cancer risks between missense and truncating mutation carriers (log-rank chi(2) = 2.48; P = 0.12). There was some evidence that mutations in exon 3 of STK11 were associated with a higher cancer risk than mutations within other regions of the gene. We found no difference in overall cancer risk between male and female carriers (log-rank chi(2) = 1.31; P = 0.25) or between familial and sporadic cases (log-rank chi(2) = 1.16, with 1 df; P = 0.28). The most common cancers represented were gastrointestinal in origin--gastroesophageal, small bowel, colorectal, and pancreatic--and the risk for these cancers at ages 30, 40, 50, and 60 years was 1%, 10%, 18%, and 42%, respectively. In women, the risk for breast cancer was substantially increased, being 32% by age 60 years. CONCLUSIONS: These results quantitatively show the spectrum of cancer risk associated with STK11 germline mutations in the context of PJS and provide a valuable reference for defining surveillance regimens.

AMP-Activated Protein Kinase Kinases↗

PubMed2004

Phenotype-genotype correlations in a series of wolfram syndrome families.

OBJECTIVE: Wolfram syndrome is an extremely rare autosomal-recessive disorder that predisposes the development of type 1 diabetes in association with progressive optic atrophy. The genetic basis of this disease has been shown to be due to mutations in the WFS1 gene. The WFS1 gene encodes a novel transmembrane protein called wolframin, which recent evidence suggests may serve as a novel endoplasmic reticulum calcium channel in pancreatic beta-cells and neurons. Genotype-phenotype correlations in this syndrome are becoming apparent and may help in explaining some of the variable characteristics observed in this disease. RESEARCH DESIGN AND METHODS: In this report, we have studied 13 patients with Wolfram syndrome from nine families to further define the relationship between mutation site and type with specific disease characteristics. RESULTS: A severe phenotype was seen in patients with mutations in exon 4 and with a large deletion encompassing most of exon 8. In total, nine novel mutations were identified as well as three new silent polymorphisms. CONCLUSIONS: Similar to all other mutation reports, most causative changes identified in the WFS1 gene occurred in exon 8, and only one was identified outside this region in exon 4.

Adolescent↗

PubMed2002

BRCA2 mutations in a population-based series of patients with ocular melanoma.

We studied the BRCA2 gene for germline mutations in 71 of 99 patients (72%) with ocular melanoma who were diagnosed consecutively in Australia in 1997 and 1998. Patients considered for our study fulfilled one of the following critiera: (i) were 50 years of age or less at diagnosis; (ii) had bilateral disease (2 patients); (iii) reported a family history of ocular melanoma (4 patients). Mutation detection was performed using the protein truncation test and denaturing high-performance liquid chromatography with primers designed to include intron-exon boundaries. Six DNA changes were found of which 2 were exonic, in exons 14 (A>C in nucleotide 7244 leading to His>Arg) and 27 (base pair substitution in nucleotide 9976 leading to a stop codon). One exonic change has been reported previously. None of the intronic mutations were deemed to affect splicing efficiency. Neither exonic mutation was in a person with bilateral ocular melanoma or a family history of cutaneous melanoma. We estimated the prevalence of possible loss of function changes in BRCA2 in patients with ocular melanoma at 3% (95% CI 0-10%). This figure was similar to previous estimates of 2.8% and 2% in nonrepresentative samples of patients with ocular melanoma and 2.1% in a representative sample of young women with breast cancer.

Adolescent↗

PubMed2002

Mutation analysis of MLH1 and MSH2 genes performed by denaturing high-performance liquid chromatography.

Mutation analysis of large genes, such as MSH2 and MLH1, is time-consuming and expensive. We investigated the sensitivity and specificity of DHPLC analysis for the detection of mutations within both MSH2 and MLH1. Studies included a series of 46 patients affected by colorectal cancer from HNPCC families. We confirmed 19 changes previously identified by DNA sequencing and, in a blind study, an additional 16 rare alterations including four mutations not previously described. Generally, false negative results were not observed. Elution profiles were highly characteristic for a given change and in 98.5% cases allowed the distinction between novel alterations and previously identified mutations and polymorphisms. For the detection of changes in almost all amplicons, it was sufficient to use just one denaturing temperature. DHPLC was confirmed to be highly sensitive, specific and a cost-effective technique with particularly high potential for the detection of MSH2 and MLH1 gene mutations in the diagnostic setting.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Direct integrin alphavbeta6-ERK binding: implications for tumour growth.

Blockade of the mitogen-activated protein (MAP) kinase pathway suppresses growth of colon cancer in vivo. Here we demonstrate a direct link between the extracellular signal-regulated kinase ERK2 and the growth-promoting cell adhesion molecule, integrin alphavbeta6, in colon cancer cells. Down-regulation of beta6 integrin subunit expression inhibits tumour growth in vivo and MAP kinase activity in response to serum stimulation. In alphavbeta6-expressing cells ERK2 is bound only to the beta6 subunit. The increase in cytosolic MAP kinase activity upon epidermal growth factor stimulation is all accounted for by beta6-bound ERK. Deletion of the ERK2 binding site on the beta6 cytoplasmic domain inhibits tumour growth and leads to an association between ERK and the beta5 subunit. The physical interaction between integrin alphavbeta6 and ERK2 defines a novel paradigm of integrin-mediated signalling and provides a therapeutic target for cancer treatment.

Amino Acid Sequence↗

PubMedDate not supplied

Electro-oculographic and electroretinographic studies in HNPCC gene mutation carriers.

PURPOSE: To assess retinal function in HNPCC gene mutation carriers. PATIENTS: 19 carriers (38 eyes) of HNPCC genes and controls. METHODS: Electro-oculogram, standard flash electroretinogram and pattern electroretinogram (PERG) recordings were performed. RESULTS: In the total group of HNPCC gene mutation carriers examined by oscillatory potentials, reduced amplitude (p < 0.0004) and increased latency (p < 0.04) of the O3 wave and increased latency (p < 0.02) of the O4 wave were found. In the subgroup of carriers with hMLH1 gene mutation, reduced amplitudes of the O3 (p < 0.0005) and O4 (p < 0.04) waves were identified. In the total group of HNPCC gene mutation carriers examined by PERG, reduced amplitudes of the P50 (p < 0.003), N95 (p < 0.02) and abnormal N95/P50 ratio (p < 0.02) were revealed. In the subgroup of hMLH1 gene mutation carriers, reduced amplitude of the P50 (p < 0.04) and abnormal N95/P50 ratio (p < 0.02) were observed, whereas in the hMSH2 gene mutation carrier subgroup, reduced amplitude (p < 0.03), shortened latency of the P50 wave (p < 0.02) and reduced amplitude of the N95 wave (p < 0.03) were found. CONCLUSION: Constitutional dysfunction of the inner retina appears to be a characteristic feature of HNPCC gene mutation carriers.

Adult↗