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Biomedical subjects

R S Scott

Publications and source records attributed to R S Scott.

At least 37 records · Page 2Linked to original sources
PubMed1999

The paleoenvironment of Sivapithecus parvada.

Remains of the hominoid Sivapithecus parvada and a diversity of mammalian taxa are preserved at locality Y311 (ca. 10 Ma) in the Siwalik Nagri Formation of northern Pakistan. Bovids (Bovidae, Artiodactyla) are the most abundant mammals next to tragulids (Tragulidae, Artiodactyla) at locality Y311 and provide a means for reconstructing the paleoenvironments that would have been available to Sivapithecus parvada. A functional model indicates a linkage between habitat and several femoral characters among extant bovids. Based on this model, we infer that forested habitats predominated at locality Y311 but that some less densely covered areas may also have been present. Paleoenvironments in the earlier Chinji Formation appear comparable to those at locality Y311, although the presence of a continuous canopy in the former is more certain. Thus, adaptive changes in the bovid fauna from the Chinji through the Nagri Formations appear to have preceded the shift to predominantly C4 grasslands which, based on other lines of evidence, occurred locally (and possibly globally) between 8 and 6 Ma. The paleoenvironments of locality Y311 and the Chinji Formation localities appear different from the paleoenvironment of Kenyapithecus at Fort Ternan in Kenya, where the presence of continuous canopy is unlikely. The Fort Ternan fauna is dominated by two genera of bovids. One of these is adapted to light cover while the other appears better adapted to heavy cover. Sivapithecus and Kenyapithecus lived in different ecological settings probably characterized by varying degrees of vegetative cover.

Animals↗
PubMed1999

Haemochromatosis gene mutations Cys282Tyr and His63Asp are not increased in Type 2 diabetic patients compared with the Canterbury (New Zealand) general population.

Genetic predisposition to haemochromatosis may be an important aetiological factor in some cases of Type 2 diabetes. Our aim was therefore to test the hypothesis that the haemochromatosis gene mutations Cys282Tyr and His63Asp are more prevalent in Type 2 diabetic patients compared with the Canterbury, New Zealand general population. We studied 230 consecutive patients referred to the Diabetes Services with age > or = 30 years and considered to have Type 2 diabetes. DNA was extracted from whole blood and amplified by polymerase chain reaction prior to restriction fragment length polymorphism analysis. The frequency of the mutations was compared with that observed previously in 1064 subjects from the Canterbury general population by chi2 testing. Iron was measured by a colorimetric method, transferrin by rate nephelometry and ferritin by immunoassay. There were 2/230 (0.8%) Cys282Tyr homozygous subjects in the diabetic group compared with 5/1064 (0.5%) NS in the general population. Although there was a trend to lower incidence of Cys282Tyr heterozygosity in the diabetic group, there was no significant difference for any of the six genotype frequencies between the two groups. Haemochromatosis gene mutations Cys282Tyr and His63Asp are therefore not increased in Type 2 diabetics compared with the general population. Transferrin saturation was a sensitive marker (100%) of genetic haemochromatosis, although ferritin had low specificity (77.8%). Genetic susceptibility to haemochromatosis is not an important aetiological factor for diabetes, and targeted screening of diabetic patients for haemochromatosis is not indicated.

Adult↗
PubMed1999

Type 2 diabetes towards the new millennium--the relative importance of glycaemic versus lipid control.

The prevalence of type 2 diabetes is set to increase. The UKPDS has shown that better average glycaemic control over time leads to a reduction in microvascular complications. Macrovascular outcomes are also reduced in overweight subjects treated with metformin. The UKPDS and our own data, however, show that the natural history of type 2 diabetes is one of progressive deterioration in glycaemic control despite treatment. Lipid parameters emerges as the strongest predictors of outcomes in type 2 diabetes and suggest where therapeutic endeavours might best be directed. Ongoing trials of lipid-modifying therapies in type 2 diabetes will help to substantiate this. In the meantime, efforts to improve glycaemic control should not be pursued to the exclusion of other abnormalities that may have a greater relevance to outcomes of type 2 diabetes. There is an urgent need for better prevention and intervention strategies as we approach the new millennium.

Blood Glucose↗
PubMed1999

Inhalation toxicity of cyclododecatriene in rats.

Cyclododecatriene (CDDT, CAS No. 4904-61-4) was tested for its inhalation toxicity in rats following repeated exposures. Male rats were exposed nose-only to CDDT for 6 hr/day, 5 days/wk for a total of 9 exposures over 2 weeks. Particular attention was paid to neurotoxicologic endpoints. Concentrations of 0 (control), 5, 50, and 260 ppm were studied. The 260 ppm chamber contained both vapor and aerosol while the 5 and 50 ppm chambers were vapor only. Four groups of 10 rats each were used to measure standard clinical signs and growth, clinical pathology (including hematology, biochemistries, and urine analysis), and tissue pathology. Another 4 groups of similar size were used for neurotoxicity testing. In the standard toxicity groups, 1/2 of the rats were sacrificed 1 day following the 9th exposure; the other half underwent a 2-week recovery period prior to being sacrificed (recovery group). During the exposures rats inhaling 260 ppm had a diminished or absent response to an alerting stimulus. Irregular respiration and lethargy were observed in these rats immediately following exposure. These signs were rapidly reversible and were not seen prior to the subsequent exposure. Body weights in rats exposed to either 50 or 260 ppm were significantly lower than the corresponding controls. No compound-related clinical pathology changes were seen in any of the test groups and tissue pathology effects only occurred in the nasal tissue. In rats exposed to 260 ppm, minimal degeneration/necrosis of nasal olfactory epithelium was observed in rats examined immediately following the exposure period. This change was not seen in the recovery rats. Functional observational battery (FOB) assessments and motor activity (MA) evaluations conducted after the 4th and 9th exposures on rats from all test groups, and specific neuropathologic evaluation on perfused brain, spinal cord, and skeletal muscle from rats exposed to 260 ppm failed to demonstrate any specific neurotoxicity. Outward signs of sedation were seen at the top level tested. Under the conditions of this test, the no-observed-adverse-effect level (NOAEL) was determined to be 5 ppm based upon a reduced rate of body weight gain in the 50 ppm group. No specific neurotoxicity was detected and the histopathologic response was limited to reversible changes in the nasal epithelia in rats exposed to 260 ppm.

Administration, Inhalation↗
PubMed1998

Lipid but not glycaemic parameters predict total mortality from type 2 diabetes mellitus in Canterbury, New Zealand.

A cohort of 447 subjects with Type 2 diabetes mellitus (208 male, 239 female; age range 30-82, median 62 years; and of predominantly European origin) was characterized in a clinic survey in 1989. Individual status (dead or alive) at 1 June 1995 was ascertained. Mortality rates were compared with the general New Zealand population by calculating standardized mortality ratios (SMR) and the hazard ratio (HR) of prognostic factors evaluated with Cox's proportional hazards model. At 6 years, 289 subjects were confirmed as alive and 133 as dead; only 25 were untraceable. Six-year survival for the cohort was 70% (95% CI 66-74). SMR was 2.53 (95% CI 1.99-2.68) for the female cohort and 2.03 (95% CI 1.60-2.59) for the male cohort. Factors assessed at baseline (1989) that were independently prognostic of total mortality included age, male sex, pre-existing coronary artery disease (CAD) (HR 2.2, 95% CI 1.5-3.3) and plasma cholesterol (HR for 1.4 mmol l(-1) change: 1.49, 95% CI 1.2-1.9). HDL-cholesterol was protective in women (HR for 0.4 mmol l(-1) change: 0.72, 95% CI 0.51-1.00) but not men. Glycated haemoglobin was not a significant predictor of total mortality. Predictors of CAD mortality (in those subjects free of CAD in 1989) included plasma cholesterol (HR for 1.4 mmol l(-1) change: 1.86 95% CI 1.20-2.89), glycated haemoglobin (HR for 1.8% change: 1.9 95% CI 1.04-3.47), male sex, peripheral vascular disease, and smoking. There is therefore increased mortality in Type 2 diabetic subjects in Canterbury, New Zealand. HDL-cholesterol is protective against total mortality in females.

Accidents↗
PubMed1998

Hospital discharges for diabetic foot disease in New Zealand: 1980-1993.

The aim of this study was to determine the prevalence of hospital discharges for diabetic foot disease from 1980 to 1993 in New Zealand and identify regional variations. Data from the International Classification of Disease (ICD) discharge codes for diabetes and its complications from 1980 to 1993 were reviewed for diabetic foot disease. The total number of discharges/100,000 total population has increased from 13.56 in 1980 to 25.79 in 1993. The age and sex-standardised total bed/days per 1000 total population increased from 5.02 in 1980 to 5.85 in 1993. The total inpatient cost for the management of diabetic foot disease in New Zealand (population 3.3 million) for 1993 is estimated to be in the region of NZ$10-11 million (USD$7-7.7 million), indicating the need to put strategies in place to manage this problem. Strategies that reduce the individual and inpatient burden of this advanced stage complication of diabetes mellitus can be implemented easily for a relatively modest cost.

Adult↗
PubMed1998

Clinical and biochemical outcomes of type 2 diabetes mellitus in Canterbury, New Zealand: a 6-year cohort study.

There is a paucity of data regarding outcomes of Type 2 diabetes mellitus. A cohort of 447 Type 2 diabetic subjects (208 male, 239 female; age range 30-82 years, median 62 years; and of predominantly European origin) was characterised in a clinic survey in 1989. Individual status (dead or alive) at 1 June 1995 was ascertained. At 6 years, 289 subjects were confirmed as alive and 133 as dead--only 25 were untraceable. Of those subjects identified as alive, follow-up clinical and biochemical data were obtained for 253 (87.5%) individuals. In those subjects, glycated haemoglobin deteriorated from 63.1 +/- 18.7 mmol/mol haem in 1989 to 71.7 +/- 24.4 in 1995, P < 0.0001. An increased prevalence of retinopathy was evident at 6-year follow-up, 59.7% cases in 1995 compared with 39.5% in 1989, P < 0.001. Similarly there was an increased prevalence of coronary artery disease (CAD) (33.6 vs 18.2% of cases), albuminuria (26.5 vs 19% of cases; P < 0.001), and hypertension (71.5 vs 54.9% of cases; P < 0.001) in 1995 vs 1989, respectively. Multiple logistic regression analysis showed that glycated haemoglobin (odds ratio (OR) for 18 mmol/mol haem change, 1.78; 95% CI, 1.15-2.85), hypertension (OR, 3.33; 95% CI, 1.40-8.41) and known duration of diabetes (OR for 7 year change, 2.12; 95% CI, 1.24-3.80) were predictors for development of retinopathy. There is therefore a deterioration in glycaemic control in Type 2 diabetes over 6 years and an increased prevalence of complications that present strategies in a multidisciplinary specialist diabetes clinic are unable to prevent on a sustainable basis.

Adult↗
PubMed1997

Replication initiation and elongation fork rates within a differentially expressed human multicopy locus in early S phase.

Replication of the 400 copies of the 43 kb human ribosomal RNA (rDNA) locus spans most of the S phase. To examine the basis for the unusual pattern of rDNA replication, a sensitive strategy was developed to map origins of DNA replication and measure apparent rates of fork progression within a chromosomal locus. This technique, termed differential intragenomic replication timing, revealed that initiation within the actively transcribed rDNA occurred in early S within a 10.7 kb region spanning the promoter and 5' external transcribed spacer. Forks emanating from this early bidirectional origin progressed at an apparent slow rate with the sense and anti-sense forks moving at 0.32 and 0.23 kb/min. Using a photochemical-based technique, the chromatin status of the rDNA repeats was assayed throughout the S phase. Approximately 85% of the rDNA repeats were in a transcriptionally active chromatin structure at the start of S phase. A progressive decrease in the transcription state of the rDNA loci was observed, reaching a minimum between 3 and 6 h in mid S phase. Altogether, the data suggest a link between RNA polymerase I mediated transcription and site-specific initiation of DNA replication within the rDNA multicopy locus.

Chromatin↗
PubMed1996

Islet cell antibodies and antibodies against glutamic acid decarboxylase in newly diagnosed adult-onset diabetes mellitus.

This study aimed to determine the prevalence of antibodies against glutamic acid decarboxylase (anti-GAD) and islet cell antibodies (ICA) in relation to beta-cell function in adults newly-diagnosed with diabetes mellitus. beta-cell function was assessed in adults aged 25-70 years newly-diagnosed with diabetes mellitus (n = 84) and control subjects (n = 34) using a 1.6 MJ mixed meal test procedure. beta-cell function was evaluated by the true insulin (defined as immunoreactive insulin minus proinsulin) response to the mixed meal test. Subjects were classified on the basis of the area under the true insulin curve (normal 16830-107700 pmol min/I) and the sum of the 30 and 60 min incremental response (normal 285-3295 pmol/I). The prevalence of anti-GAD and ICA was determined using radioimmunoprecipitation and indirect immunofluorescence, respectively. Twelve (14%) of the study cohort were insulin deficient showing little or no true insulin release. Of the insulin deficient individuals, seven (58%) subjects were anti-GAD antibody positive, compared with eleven (15%) of the subjects without insulin deficiency (P < 0.001). Seven (58%) insulin deficient subjects were ICA positive, whereas only two (3%) non-insulin deficient subjects were ICA positive (P < 0.001). Eight (67%) of the insulin deficient individuals had anti-GAD or ICA, compared with twelve (17%) of those who were not insulin deficient (P < 0.001). The positive predictive values for insulin deficiency of anti-GAD and ICA were 39 and 78% respectively. The sensitivity of both antibodies for detecting insulin deficiency was 50%. The specificity for detecting insulin deficiency was 85% for anti-GAD and 97% for ICA. Positivity for both anti-GAD and ICA gave a specificity and positive predictive value for insulin deficiency of 99%, and a sensitivity of 50%. Nearly one in seven adults presenting with diabetes mellitus as a new diagnosis are insulin deficient using our criteria. Loss of beta-cell function in two thirds of individuals who are insulin deficient can be identified by anti-GAD and ICA. Early detection of these immune markers of beta-cell damage creates the potential for immune modulation to limit such damage.

Adult↗
PubMed1995

Fluvastatin for dyslipoproteinemia, with or without concomitant chronic renal insufficiency.

Renal insufficiency is frequently associated with both quantitative and qualitative abnormalities in lipid and hemorheologic profiles. Although this may lead to increased risk of cardiovascular disease, a number of studies have also shown dyslipidemia to be a significant risk factor for the progression of renal insufficiency in human chronic renal disease. This double-blind, placebo-controlled trial aimed to assess the effect of fluvastatin, a synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on these parameters in dyslipidemic patients with or without chronic renal insufficiency. After a 6-week placebo run-in, 42 patients who had been previously stratified into 2 groups on the basis of creatinine clearance levels (0.5-1.0 mL/sec or > 1.0-1.5 mL/sec) were randomized to treatment with fluvastatin (40 mg daily) or matching placebo. Significant differences (on analysis of variance with repeated measures) were seen between fluvastatin and placebo treatment groups for changes in total cholesterol (-15% vs 1%, respectively; p < 0.001), low density lipoprotein cholesterol (LDL-C; -21% vs -5%; p < 0.001), very low density lipoprotein cholesterol (-14% vs 14%; p = 0.017), very low density lipoprotein triglycerides (-1% vs 29%; p = 0.014) and total triglycerides (-7% vs 24%; p < 0.001). These effects on cholesterol levels were reflected in a significant decrease in apolipoprotein B levels with fluvastatin therapy (p < 0.001). Apolipoprotein A-I levels increased (p = 0.054) despite no significant change in the levels of high density lipoprotein cholesterol. Response to therapy did not differ between the 2 renal function groups for any of the lipid, lipoprotein, and apolipoprotein variables. Hemorheologic parameters were not altered with fluvastatin therapy, regardless of renal function.(ABSTRACT TRUNCATED AT 250 WORDS)

Anticholesteremic Agents↗
PubMed1995

Screening for mutations in exon 4 of the LDL receptor gene: identification of a new deletion mutation.

DNA from 14 unrelated New Zealand familial hypercholesterolaemia (FH) heterozygotes, originating from the United Kingdom, was screened for mutations in exon 4 of the low density lipoprotein receptor (LDLR) gene. One patient was heterozygous for mutation D206E, which was initially identified in South Africa. The chromosomal background of this mutant allele was compatible with that described previously in Afrikaner and English patients, suggesting that this mutation originated in the United Kingdom. The 2 bp deletion in codon 206 and mutations D154N and D200G, previously reported in English FH patients, were not detected in this sample. In one of the patients, however, a new deletion of 7 bp was identified after nucleotide 581 (or 582) in exon 4 of the LDLR gene.

Adult↗
PubMed1995

Immunogenetic, clinical, and demographic characterization of childhood type I diabetes in New Zealand.

OBJECTIVE: To examine the relationship between genetic susceptibility alleles and islet cell antibodies (ICAs) in type I diabetes. RESEARCH DESIGN AND METHODS: The human leukocyte antigen (HLA)-DQB1 alleles and ICA levels of all incident type I diabetic cases in patients < 20 years of age diagnosed in 1990 and 1991 in Canterbury, New Zealand, were determined. RESULTS: The mean annual incidence rate for type I diabetes over the 24 months was 19.0/100,000 patient-years (95% confidence interval [CI] 13.5-26.0/100,000), which was considerably higher than rates observed between 1982 and 1989 (11.7/100,000; 95% CI 9.6-14.3/100,000). ICAs > or = 10 Juvenile Diabetes Foundation units (JDF U) were present in 84.6% of the subjects, but there was a higher prevalence of ICA-negative (ICA-) subjects among those diagnosed during the winter months. The frequencies of the susceptibility allele DQB1*0302 and susceptibility genotype 0302/0201 were 71.8% and 43.5%, respectively. Subjects with 0302 tended to be younger (mean age 8.3 +/- 5.1 years) than those with nonsusceptibility types (mean age 11.8 +/- 4.7 years, P = 0.056). The probability of being ICA positive (ICA+) was not significantly different between subjects with allele 0302 (85.7%) and those without it (81.8%). All seven patients negative for ICA were homozygous for DQB1 nonaspartate-57. There was no clustering of the immunogenetic markers with demographic and clinical characteristics apart from age at diagnosis. CONCLUSIONS: No direct relationship was observed between DQB1-defined genetic susceptibility and ICA at diagnosis, suggesting that variations at the DQB1 locus are not linked to the expression of this autoimmune marker of beta-cell destruction.

Adolescent↗