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Biomedical subjects

C Robinson

Publications and source records attributed to C Robinson.

At least 505 records · Page 28Linked to original sources
PubMedDate not supplied

Urinary excretion of albumin, alpha-1-microglobulin, and N-acetyl-B-D-glucosaminidase in relation to smoking habits in diabetic and nondiabetic subjects.

Smoking may be a risk factor for the development of diabetic nephropathy. Therefore, the urinary excretion of albumin, alpha-1-microglobulin, and N-acetyl-BD glucosaminidase was studied in 24 young adult diabetic patients who smoked. None of these patients had urine samples positive for albumin as determined by the Albustix method (i.e., a urinary concentration of albumin of less than 0.5 g in 24 hr). Control groups were nonsmoking diabetic patients (matched for age and duration of diabetes) and nondiabetic subjects (smokers and nonsmokers). Expired breath carbon monoxide and the urinary nicotine metabolite cotinine were measured as objective markers of smoking load. No significant differences in concentrations of urinary proteins were found among any of the four groups. Therefore, smoking is not associated with the development of an increased urinary excretion of albumin within the "microalbuminuria" range. However, further studies are required to determine whether smoking is a risk factor for the progression of established microalbuminuria to Albustix positive proteinuria in diabetic patients.

Adult↗
PubMedDate not supplied

Distribution profiles of fluoride in three different kinds of rat bones.

The study was performed to reveal the detailed distribution profiles of fluoride in three different kinds of rat bone--humerus, vertebral arch, and parietal bone--and to compare this with the histological appearance of each bone type. Two groups of Wistar rats were provided water ad libitum containing 0 and 100 ppm fluoride, respectively, for 24 weeks. The fluoride distribution profiles across the bone of the three different bones from the outer to the inner surface were determined by means of an abrasive micro-sampling technique. In control animals, both humerus and parietal bones showed higher concentrations at the periosteal and endosteal surfaces, while the vertebral arch showed additional high levels in the middle (containing trabecular bone) of the tissue. In exposed animals, fluoride levels increased greatly in all three bone types. The vertebral and parietal fluoride distribution profiles were relatively unchanged, although humerus fluoride increased from periosteum to endosteum. The differences in fluoride distribution profiles were apparently related to the histological appearances of these bones. The surface area of bone available and the extent of vascularity appear to affect fluoride uptake.

Animals↗
PubMedDate not supplied

Fluoride profiles in dental calculus from Japanese, Chinese and British residents.

Whether the fluoride concentrations and profiles differ in human dental calculus obtained from different countries was investigated. A total of 203 dental calculus deposits on 203 permanent teeth from residents (mean age, 52.1 years) of Nagoya (Japan), Shanghai (China), Leeds (Great Britain) and the Wuhan mountainous area (China, fluoridated area) were analysed. An abrasive microsampling procedure was used to examine fluoride distribution. There were five types of fluoride profiles in dental calculus in each area/country (designated types L, J, U, T, W). In supragingival calculus, type L (highest in the outermost layers) and type J (highest in the innermost layers) both had significantly higher values than type U (high in the surface and innermost layers) but were relatively identical. In subgingival calculus, type W (high in the outermost, mid and innermost layers) was characteristics. Calculus from the Wuhan mountainous area (fluoridated) had the highest fluoride concentration, followed by Leeds (non-fluoridated), and Nagoya and Shanghai (non-fluoridated) calculus had the lowest. Fluoride concentrations in supragingival calculus were higher in teeth extracted because of periodontal diseases than dental caries. It is concluded that fluoride concentrations and distribution in dental calculus differ from country to country, probably due to different fluoride environments.

Adult↗
PubMedDate not supplied

Time trends in human dietary exposure to PCDDs, PCDFs and PCBs in the UK.

Total Diet Study samples collected in 1982 and 1992 were analysed. Estimated dietary intakes of PCDDs, PCDFs and PCBs by UK consumers were found to have fallen substantially during this period and are now considerably below the Tolerable Daily Intake (TDI). Composite samples of human milk were also analysed for PCDDs, PCDFs and PCBs. Estimated combined dietary intakes of PCDDs, PCDFs and PCBs by breast fed infants in 1993-94 via breast milk fell from 170 pg TEQ/kg bodyweight/day at 2 months to 39 pg TEQ/kg bodyweight/day at 10 months.

Adolescent↗
PubMedDate not supplied

Anger of African American women in the south.

In this existential-phenomenological investigation middle-class African American women (n = 9) in the Southern United States were interviewed about their experience of anger in daily life. The purpose of the study was to examine what African American women's anger is about, what it means, and how it is experienced. Transcribed interviews were analyzed using a hermeneutic process. The thematic structure of African American women's anger comprises three main elements that stand out as figural: power, control, and respect. These figural elements can be understood only when seen against the ground of a racist Southern culture that produces pervasive mistrust. These findings are of importance to clinicians, who cannot deliver culturally competent interventions to African American female clients without a clear understanding of the complexity and meaning of their anger experience.

Adult↗
PubMedDate not supplied

Lead in feed incident--multi-element analysis of cattle feed and tissues by inductively coupled plasma-mass spectrometry and co-operative quality assurance scheme for lead analysis of milk.

Contaminated cattle feed was imported into the UK in 1989 and resulted in lead toxicity in some animals. Rapid analyses for lead and several other possible contaminating elements were required for feed and cattle tissues. Microwave dissolution of samples with measurement by ICP-MS was used for multi-element determinations. Lead was found to be the major contaminant. Lead levels in milk samples were measured by several laboratories during the crisis and an analytical quality assurance scheme was devised to monitor the quality of the data. The scheme allowed any poorly performing laboratories to be rapidly identified and excluded from the survey.

Animal Feed↗
PubMedDate not supplied

Mechanisms of myocardial ischemia induced by epinephrine: comparison with exercise-induced ischemia.

The role of epinephrine in eliciting myocardial ischemia was examined in patients with coronary artery disease. Objective signs of ischemia and factors increasing myocardial oxygen consumption were compared during epinephrine infusion and supine bicycle exercise. Both epinephrine and exercise produced myocardial ischemia as evidenced by ST segment depression and angina. However, the mechanisms of myocardial ischemia induced by epinephrine were significantly different from those of exercise. Exercise-induced myocardial ischemia was marked predominantly by increased heart rate and rate-pressure product with a minor contribution of end-diastolic volume, while epinephrine-induced ischemia was characterized by a marked increase in contractility and a less pronounced increase in heart rate and rate-pressure product. These findings indicate that ischemia produced by epinephrine, as may occur during states of emotional distress, has a mechanism distinct from that due to physical exertion.

Arousal↗
PubMedDate not supplied

Educational achievements, employment and social class of insulin-dependent diabetics: a survey of a young adult clinic in Liverpool.

The educational achievements, current employment, and social class of 137 diabetic patients aged 20.9 +/- 3.0 years (mean +/- SD), attending a Young Adult Diabetic clinic in North Liverpool were surveyed. The duration of diabetes was 7.8 +/- 5.0 years. Patients who developed diabetes in childhood (age at diagnosis less than 13 years) were more likely to have achieved educational qualifications, be employed, and be of social class I or II than those developing diabetes aged 13-25 years. Compared with non-diabetic young adults from North Liverpool, diabetics achieved similar educational qualifications and were as likely to be employed after leaving full-time education. This is an encouraging finding in the present harsh economic climate. The clustering of social classes I and II in childhood diabetics found in this study requires a larger epidemiological study of social class and insulin-dependent diabetes for confirmation.

Adult↗
PubMedDate not supplied

Distribution of exogenous proteins in caries lesions in relation to the pattern of demineralisation.

While it is believed that proteins may protect enamel from demineralisation, recent work has indicated that such material may also hinder remineralisation. For example, albumin will inhibit apatite crystal growth in vitro and is present in carious enamel in vivo. However, it is not clear whether (1) the distribution of proteins within lesions is restricted to specific lesion zones or (2) the origin of such proteins is endogenous (i.e. as a remnant of the developmental process) or exogenous, originating in the saliva or gingival crevicular fluid. The present study used a combination of immunohistochemistry and microradiography to determine the distribution of two proteins, serum albumin and salivary amylase, within natural white-spot carious lesions in relation to specific levels of demineralisation. The results indicated that albumin is found primarily in a region of between 10 and 20% demineralisation (an area of transition between the 'dark' zone and lesion 'body'), with smaller quantities occurring in the region between 0 and 10% demineralisation and trace amounts in the zone indistinguishable from sound enamel by microradiography. A similar distribution was found for amylase in that the heaviest labelling was within the 10-20% demineralisation zone, although little if any was present in the 0-10% zone. The presence of these molecules in a region of the lesion where some potential for reprecipitation may exist will have important implications with respect to lesion progression.

Albumins↗
PubMedDate not supplied

Fluoride profiles in dental plaque in vivo formed on fluoride pre-treated human enamel.

Using a novel device capable of generating plaque in vivo on a natural enamel substrate, it has been possible to determine fluoride profiles from the saliva-plaque interface towards the enamel surface. Fluoride profiles in dental plaques tended to fall from the saliva-plaque interface towards the enamel. The device also offered the possibility of examining fluoride distributions after pre-treatment of the enamel with fluoride in vitro. Fluoride profiles were determined in plaque generated in vivo on enamel surfaces, which had been previously treated with a 900-ppm fluoride solution. The results showed the previously reported fall from the plaque surface, but in addition, a further rise towards the enamel surface was seen. The data imply that enamel loaded with fluoride can release some of this fluoride back into the plaque and may act as a fluoride reservoir.

Calcium↗
PubMedDate not supplied

Effect of experimental fluorosis on the surface topography of developing enamel crystals.

Dental fluorosis is an increasing problem, yet the precise mechanism by which fluoride exerts its effects remains obscure. In the present study, we have used atomic force microscopy to image and quantitate surface features of enamel crystals isolated from specific developmental stages of fluorotic and control rat incisors. The results showed a significant decrease in crystal surface roughness with development in control tissue. Crystals from fluorotic tissue were significantly rougher than controls at all stages of development, did not decrease in roughness during the later stages of their development and had many morphological abnormalities. These data clearly demonstrate an effect for fluoride on enamel crystal surfaces which could reflect changes in the nature and distribution of growth sites and/or in mineral-matrix interactions. These would be expected to affect crystal growth during maturation, resulting in the characteristic porous appearance of fluorotic lesions in mature teeth.

Animals↗
PubMedDate not supplied

In vitro studies of the penetration of adhesive resins into artificial caries-like lesions.

Instead of removing the porous carious tissue at a relatively late stage in the disease process, attempts have been made to 'fill' the microporosities of lesions at a much earlier stage of lesion development. This would not only reduce the porosity and therefore access of acid and egress of dissolved material, but also afford some mechanical support to the tissue and perhaps inhibit further attack. Successful infiltration of materials into lesions has been demonstrated previously using resorcinol-formaldehyde which, however, was clinically unacceptable. The advent of dental adhesives with potentially suitable properties has prompted a re-examination of this concept. Artificial lesions of enamel were generated in extracted human teeth using acidified gels. A range of currently available adhesive materials was then used to infiltrate the porosities. The extent of occlusion of the lesion porosities was determined both qualitatively using light microscopy and quantitatively using a chloronaphthalene imbibition technique. The effect of such treatment upon subsequent exposure to acid gels was also investigated. Results showed that up to 60% of the lesion pore volume had been occluded following infiltration with some of the materials and that this treatment was capable of reducing further acid demineralization. The development of such treatment strategies could offer potential noninvasive means of treating early enamel lesions.

Adhesives↗
PubMedDate not supplied

Fluoride intake in Japanese children aged 3-5 years by the duplicate-diet technique.

This study was conducted to determine the fluoride intakes in 94 preschool children aged 3, 4 and 5 (n = 30, 30, 34, respectively) residing in Yokkaichi, Mie Prefecture (< 0.16 ppm F water supply). The parents duplicated all the diets that their children ingested on 3 separate days during a 1-year period. The acid-diffusible fluoride in the diet was isolated by the acid-diffusion technique and measured with a fluoride electrode. The mean daily fluoride intakes from diet alone by children aged 3, 4 and 5 were 0.30 mg (n = 29, SD 0.19), 0.28 mg (n = 30, SD 0.19) and 0.30 mg (n = 34, SD 0.19), respectively. The total estimated mean values from diet and dentifrice were 0.35 mg (n = 29, SD 0.22, range 0.13-1.00), 0.33 mg (n = 30, SD 0.19, range 0.13-0.86) and 0.39 mg (n = 34, SD 0.18, range 0.18-1.01), respectively. It was concluded that the mean (+/-SD) total fluoride from diet and dentifrice in 3- to 5-year-old Japanese children was 0.35 +/- 0.19 mg/day (0.021 +/- 0.012 mg/kg body weight).

Analysis of Variance↗
PubMedDate not supplied

The effect of fluoride on the developing tooth.

This review aims to outline the effects of fluoride on the biological processes involved in the formation of tooth tissues, particularly dental enamel. Attention has been focused on mechanisms which, if compromised, could give rise to dental fluorosis. The literature is extensive and often confusing but a much clearer picture is emerging based on recent more detailed knowledge of odontogenesis. Opacity, characteristic of fluorotic enamel, results from incomplete apatite crystal growth. How this occurs is suggested by other changes brought about by fluoride. Matrix proteins, associated with the mineral phase, normally degraded and removed to permit final crystal growth, are to some extent retained in fluorotic tissue. Fluoride and magnesium concentrations increase while carbonate is reduced. Crystal surface morphology at the nano-scale is altered and functional ameloblast morphology at the maturation stage also changes. Fluoride incorporation into enamel apatite produces more stable crystals. Local supersaturation levels with regard to the fluoridated mineral will also be elevated facilitating crystal growth. Such changes in crystal chemistry and morphology, involving stronger ionic and hydrogen bonds, also lead to greater binding of modulating matrix proteins and proteolytic enzymes. This results in reduced degradation and enhanced retention of protein components in mature tissue. This is most likely responsible for porous fluorotic tissue, since matrix protein removal is necessary for unimpaired crystal growth. To resolve the outstanding problems of the role of cell changes and the precise reasons for protein retention more detailed studies will be required of alterations to cell function, effect on specific protein species and the nano-chemistry of the apatite crystal surfaces.

Amelogenesis↗