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Biomedical subjects

C Roberts

Publications and source records attributed to C Roberts.

At least 19 recordsLinked to original sources
PubMed1996

Asthma deaths in Washington State, 1980-1989: geographic and demographic distributions.

BACKGROUND: Asthma prevalence and mortality rates have been increasing for the past two decades for reasons that are not definitively known. Few studies of asthma mortality rates have concentrated on subnational regions, such as individual states. OBJECTIVE: To determine geographic and demographic patterns of asthma mortality in Washington State during 1980 through 1989 and to compare aggregated data with patterns of chronic bronchitis mortality. METHODS: Age-adjusted mortality rates for asthma and chronic bronchitis were calculated from 1980 through 1989 for all age groups. Rates were then disaggregated by county, gender, age, and race. Rates were calculated from death certificates listed by the Washington State Center for Health Statistics as either asthma (ICD9-493) or chronic bronchitis (ICD9-490 and 491) and census data. RESULTS: During the period 1980-1989, age-adjusted mortality rates for asthma increased by 15% while those for bronchitis decreased by 43%. There was no consistent geographic pattern in the increase, though one county with a very small population had the highest rate of increase. Female asthma mortality rates increased during the decade, while male asthma mortality rates and both male and female bronchitis rates decreased. Two populations demonstrated pronounced increases in asthma mortality rates: females between ages 40 and 69 years and non-whites. CONCLUSIONS: While increased asthma mortality rates have been noted elsewhere for non-whites, this is the first study to demonstrate elevated mortality rates for middle aged women. The explanation for this remains a mystery.

Adolescent↗
PubMed1995

A survey of job stress and job satisfaction among DSAs in the north-west of England.

This study was a survey of job stress and job satisfaction among DSAs in general practice in the north-west of England during 1993. The results suggest that severe overall job stress and dissatisfaction were not prevalent but do present an important problem for a minority. The chief sources of stress are ranked. Those which caused moderate to severe stress were: running behind time, feeling under-valued by the dentist and handling difficult patients. Those experiencing greater stress outside work were more likely to report stress within it. Having a regular staff meeting, an annual salary review and a clear job description were associated with significantly less job stress.

Adult↗
PubMed1995

A mechanism for pentamidine-induced hyperkalemia: inhibition of distal nephron sodium transport.

OBJECTIVES: To determine whether pentamidine directly affects the transport of renal ions and thus provides a mechanism for hyperkalemia, which develops in as many as 100% of patients with the acquired immunodeficiency syndrome (AIDS) who receive pentamidine for more than 6 days. DESIGN: Transepithelial and single-channel electrical measurements were made on two models of distal-nephron ion transport: an amphibian distal-nephron cell line (A6) and primary cultures of rabbit cortical collecting tubules. RESULTS: Luminal bath application of pentamidine to A6 monolayers inhibited the amiloride-sensitive, short-circuit current with a 50% inhibitory concentration of 700 microM (five experiments). In the principal cell apical membranes of cortical collecting tubule primary cultures, amiloride-sensitive, 4-picosiemen Na+ channels in cell-attached patches were also identified. When the luminal membrane was directly exposed to 1.0 microM of pentamidine in the patch pipette solution, channel activity decreased by 40% (11 experiments). Channel inhibition rapidly reversed with washout of intrapipette pentamidine (four experiments). In contrast, replacement of either the luminal bath outside the patch pipette (four experiments) or the serosal bath (five experiments) with pentamidine did not significantly affect Na+ channel activity in the patches. CONCLUSIONS: Luminal or "urinary" pentamidine inhibits distal nephron reabsorption of Na+ by blocking apical Na+ channels in a manner similar to "potassium-sparing" diuretics (for example, amiloride and triamterene). This results in a decrease in the electrochemical gradients that drive secretion of distal nephron K+. Because pentamidine is eliminated through urinary excretion, this renal tubular effect provides a mechanism for pentamidine-induced hyperkalemia.

Animals↗
PubMed1995

Psychological and rheumatic symptoms of women requesting silicone breast implant removal.

In this case series, we describe the psychological and rheumatic symptoms of 52 women requesting breast implant removal. Main outcome measures include psychological evaluation with the Brief Symptom Inventory and the Beck Depression Inventory. Clinical evaluation was performed using a rheumatic symptom survey. Results noted elevation of all Brief Symptom Inventory subscales (highest in Somatization and Obsessive-Compulsive), and the Beck Depression Inventory showed mild depression. Rheumatic survey noted a mean of 12 of 23 symptoms. In conclusion, psychological distress and mild depression are noted in this group, who also may experience rheumatic symptoms of connective tissue disease. There was a moderate positive correlation between rheumatic symptoms and psychological distress.

Breast Implants↗
PubMed1995

Analysis of the inherent error of the TMS-1 Topographic Modeling System in mapping a radially aspheric surface.

The potential spherical bias of the Topographic Modeling System (TMS) in measuring a radially aspheric surface was investigated. The radii of curvature of an ellipsoidal surface were measured experimentally using the TMS, and calculated using both an instantaneous radius of curvature formula and a spherically biased algorithm for comparison. Measurements were made aligned and under four conditions of misalignment. A sphere with the same radius of curvature as the apex of the ellipsoid was used to document the fundamental performance of the system. The TMS demonstrated increasing error from center to periphery in measurement of an ellipsoid with 7.5 mm apical radius of curvature and 0.5 eccentricity. Greater than 3 D of error was present at 4 mm from the apex. The misalignment error was small compared to the inherent error in the system performance. The TMS does not accurately measure the instantaneous radii of curvature of an ellipsoidal surface due to an inherent spherical bias. In addition, the spherically biased system may not detect subtle shifts in curvature in the peripheral regions, causing potentially inaccurate reconstruction of patterns of curvature.

Algorithms↗
PubMed1995

Neuropsychological function and MRI abnormalities in neurofibromatosis type 1.

This study investigated the relationship between MRI abnormalities and cognitive function in neurofibromatosis type 1.40 children aged eight to 16 years underwent comprehensive neuropsychological, medical and neuroradiological assessments. MRI scans revealed a characteristic pattern of T2-weighted signals ('UBOs') located primarily in the basal ganglia, brainstem and cerebellum in 25 of the children. Reductions in global IQ, attention, and visuopatial and executive functions were shown to occur in association with the presence of UBOs. These findings establish a link between changes in neuropsychological functions and MRI abnormalities in NF-1, and further support neuropathological findings which suggest that UBOs may be a manifestation of delayed or disordered myelination.

Adolescent↗
PubMed1995

Temporal recovery of short-term repopulating HSC subpopulations in marrow following schedule-dependent administrations of IL-1 alpha and M-CSF.

Studies were carried out to establish the temporal effects of abbreviated administrations of IL-1 and IL-1 plus M-CSF as rescue agents on multipotential and short-term repopulating hematopoietic stem cell (HSC) subpopulations in murine marrow treated with a myelosuppressive dose of 150 mg/kg 5-FU. The recovery kinetics for high-proliferative-potential colony-forming cells (HPP-CFC), CFU-S8 and -S12, and both CFU-M and CFU-G compartments were monitored over a 14-day interval in 5-FU-treated bone marrow (FUBM) following daily cytokine injections over a 4-day interval. Both IL-1 and the coadministration of IL-1 and M-CSF rapidly enhanced the recovery of the HPP-CFC in FUBM to supranormal levels and maintained these levels for extended intervals. Moreover, since M-CSF was unable to influence the recovery of the HSC subpopulations in FUBM by itself, the results of the two cytokines amounted to a synergistic effect on the recovery of the HPP-CFC in FUBM and a reduction of severe neutropenia in the myelosuppressed animal. Scheduling studies demonstrated that these synergistic effects were restricted to those schedules in which M-CSF was coadministered with IL-1 during the first 2 days of cytokine rescue. Finally, the recovery curves generated for the HSC and CFU-M subpopulations in response to IL-1 (with or without M-CSF) also suggest that these cytokines may conceivably alter the normal balance between proliferation and differentiation within CFU-S8 and -S12 during the accelerated recovery of hematopoiesis in FUBM.

Animals↗
PubMed1995

Chemopreventive effect of green tea (Camellia sinensis) among cigarette smokers.

Chemopreventive effects of green tea and coffee among cigarette smokers were examined in 52 clinically healthy male subjects between 20 and 52 years of age. Blood specimens were obtained from nonsmokers (group I), smokers (group II), smokers consuming green tea (group III), and smokers drinking coffee (group IV). The mean number of cigarette smoking years (> 10 cigarettes/day) in groups II-IV ranged from 13.4 to 14.7 years. Daily intake of green tea and coffee was 2-3 cups/day for 6 months (groups III and IV). The frequencies of sisterchromatid exchange (SCE) in mitogen-stimulated peripheral lymphocytes from each experimental group were determined and analyzed statistically. SCE rates were elevated significantly in smokers (9.46 +/- 0.46) versus nonsmokers (7.03 +/- 0.33); however, the frequency of SCE in smokers who consumed green tea (7.94 +/- 0.31) was comparable to that of nonsmokers, implying that green tea can block the cigarette-induced increase in SCE frequency. Coffee, in contrast, did not exhibit a significant inhibitory effect on smoking-induced SCE.

Adult↗
PubMed1995

Dyslipidemias in childhood. An overview.

This article reviews the current screening and treatment guidelines for dyslipidemias in the pediatric and adolescent populations. In addition, the components of a comprehensive lipid program are reviewed.

Adolescent↗
PubMed1994

Inflammatory lesions of ribs: an analysis of the Terry Collection.

The aim of this paper is to consider the diagnostic criteria for tuberculosis in ancient populations. It investigates the frequency of periosteal new bone formation on the visceral surfaces of ribs from 1718 individuals from the Terry Collection, Smithsonian Institution, Washington D.C. and attempts to determine the aetiological factors producing these lesions. Numbers of individuals with lesions according to cause of death were recorded and the patterning of lesions compared between people who had died from tuberculosis and those whose cause of death was unrelated to a pulmonary disease. Rib lesions were more common in individuals dying from tuberculosis (61.6% or 157 of 255) than in individuals dying from other causes (15.2% or 165 of 1086). It is suggested that tuberculosis at a peripheral lung focus may disseminate directly through the pleura to the visceral surfaces of the ribs, or that pulmonary tuberculosis may be the cause of empyema of the pleural cavity and that this, per se, may initiate inflammatory change on the visceral surfaces of ribs. The nonrecognition or description of these often very subtle proliferative lesions on ribs by radiological examination of tuberculous victims is significant in the discussion of bone changes in tuberculosis. The possibility that individuals with no recorded history of tuberculosis at death actually suffered from the disease was considered in light of the frequency of rib lesions and noncorrelation with a tuberculous cause of death. Differential diagnoses are discussed including the possibility that the lesions represent a general non-specific indicator of stress.

Adolescent↗
PubMed1994

Early alveolar ridge osteogenesis following tooth extraction in the rat.

Following tooth extraction, fluorochrome bone labels were injected intraperitoneally at intervals to identify mineralizing bone surfaces. At 5, 10 and 14 days post-extraction, the rats were killed. The mineral apposition rate, mineralizing surface and mineral formation rate were determined at various locations around the healing tooth socket. Linear trends in mineral apposition rate (p < 0.000001), mineralizing surface (p < 0.000001) and mineral formation rate (p = 0.00008) were seen around the socket, decreasing from gingivopalatal to gingivobuccal regions. These differences may be due to variations in vascularity as the gingivopalatal region is adjacent to the greater palatine artery. The mineral formation rate and mineralizing surface were significantly higher in the rats killed at 14 days after tooth extraction than at the other two post-extraction time points. This may be related to an earlier peak rate of bone resorption.

Alveolar Process↗
PubMed1994

Current gestational age-related incidence of major intraventricular hemorrhage.

The overall incidence of germinal matrix intraventricular hemorrhage (GMIVH) for an inborn population of 250 very low birth weight infants from 1991 through 1993 was 20%; the incidence of major GMIVH was 5.2%. Of infants < or = 25 weeks, 60% survived and 94% of the survivors were free of major GMIVH, whereas 94% of infants > or = 25 weeks survived and 99% had no major GMIVH.

Cerebral Hemorrhage↗
PubMed1994

Changes in public knowledge and attitudes to HIV/AIDS in Wales, 1987 to 1992.

This paper presents information on changes in public knowledge and attitudes to HIV/AIDS in Wales between 1987 and 1992. The results indicate that throughout this period the majority of adults in Wales were aware of the high risk of infection from sexual intercourse and sharing needles with, and coming into contact with the blood of, someone with HIV. Nevertheless, the proportion who said that sexual intercourse with someone with HIV carries a high risk declined, and in 1992 confusion still remained about the nature of HIV infection amongst a substantial minority of respondents. More than one in ten of the adults in the most recent survey were of the opinion that kissing or being near someone with HIV who is coughing or sneezing carries a high risk of infection. The data also indicate that attitudes to those with HIV remained uneven in 1992. Whilst a greater proportion in 1992 than in 1987 held the view that people with HIV should be able to live normally in the community, attitudes appear to have hardened towards those perceived to be practising high risk behaviours, such as injecting drug users and homosexuals. The data also suggest that attitudes appear to be closely related to levels of knowledge. Given the apparent confusion and prejudice highlighted by the surveys, it is suggested that there is a continuing need for general campaigns to maintain public awareness of HIV-related issues, although this must also be complemented by more in-depth targeted education programmes.

Acquired Immunodeficiency Syndrome↗