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Biomedical subjects

R C Graham

Publications and source records attributed to R C Graham.

At least 19 recordsLinked to original sources
PubMed2006

Clinimetric properties of a walking scale in peripheral neuropathy.

Difficulty in walking is seen in many people with peripheral neuropathies, but walking ability is not comprehensively measured by commonly used outcome measures. The clinimetric properties of the 12-Item Multiple Sclerosis Walking Scale (MSWS-12, renamed the Walk-12) were investigated in 65 patients with peripheral neuropathies. Owing to its excellent internal consistency and reliability, and strong correlation with measures of physical and social function (r>0.8), the Walk-12 is recommended for measuring walking ability in peripheral neuropathies.

Adult↗
PubMed2006

A modified peripheral neuropathy scale: the Overall Neuropathy Limitations Scale.

A new peripheral neuropathy activities measure, the Overall Neuropathy Limitations Scale (ONLS), was derived by modifying the Overall Disability Sum Score (ODSS) slightly. Its inter-rater reliability was found to be high and its correlation with the ODSS (r = 0.97), 36-item Short Form Questionnaire Physical Component Summary Score, and participation and impairment measures was significant. Acceptable responsiveness (standardised response mean 0.76) was shown by the ONLS. The results obtained from the questionnaire agreed closely with those obtained from observation of the tasks on the ONLS, but were not equivalent. The simplicity of the ODSS is shared by the ONLS, but the ONLS has better content validity and less ceiling effect, which may make it more useful for clinical practice and research.

Persons with Disabilities↗
PubMed2002

Water source utilization by Pinus jeffreyi and Arctostaphylos patula on thin soils over bedrock.

Stable isotopes were used to evaluate water sources for co-occurring Jeffrey pine (Pinus jeffreyi Grev & Balf.) and greenleaf manzanita (Arctostaphylos patula Greene) in the southern Sierra Nevada, California, where soils averaged only 75 cm thick but were underlain by up to 5 m of weathered granitic bedrock. Soils and underlying weathered bedrock were sampled three times during both the 1997 and 1998 growing seasons, in 25 cm increments, from 0 to 400 cm or until hard bedrock was reached, and plant stem tissue was sampled simultaneously. Extracted water from the soil/bedrock substrate and plant tissue was analyzed for delta(18)O and/or deltaD, and depth of water source was determined by inference in conjunction with moisture status of the substrate. Water source utilization over the growing seasons for both plants generally followed a pattern similar to that observed for water depletion. Predominant water use was initially from the surface soils. Progressively deeper water sources, including weathered bedrock to a depth of several meters, were exploited as the season progressed and the overlying substrate was depleted of moisture. Early in the growing season, stable isotope values were slightly lower for pine than for manzanita (e.g., average deltaD in June 1997 was -81 per thousand for pine and -77 per thousand for manzanita), and suggest that the functional rooting depth for pine may have been slightly greater than for manzanita. In September 1997, manzanita deltaD values averaged -57 per thousand while pine values averaged -85 per thousand, indicating that manzanita opportunistically utilized summer precipitation while pine used more dependable bedrock water. In 1998, soils remained moist through July due to a late snowfall. Unlike the previous year, pine and manzanita deltaD values were not significantly different in mid- and late-growing season, and both plants exploited bedrock-derived water as soil water was depleted. Water held within bedrock was essential for meeting plant transpirational requirements over the summer drought.

Adaptation, Physiological↗
PubMed2001

Reconstruction of the historical changes in mycorrhizal fungal communities under anthropogenic nitrogen deposition.

Archived soil samples (1937-1999) and historic air quality data from the Los Angeles Basin were used for reconstructing the record of change between atmospheric NO(x) loads, soil delta(15)N values and the diversity of arbuscular mycorrhizae (AM), which are ubiquitous plant-fungus mutualists that control plant community productivity. A tripling of atmospheric NO(x) loads between 1937 and the 1970s was paralleled by soil nitrogen enrichment (delta(15)N = 3.18). From 1975 onwards, atmospheric NO(x) declined, but soils became nitrogen saturated (delta(15) N = -4 and NO(3)-nitrogen = 171mgkg(-1)). The shifts in the AM community followed 28 years of atmospheric nitrogen enrichment and coincided with the onset of soil nitrogen saturation. Such changes were manifest in the loss of AM productivity, species richness (one species per year), three genera (Acaulospora, Scutellospora and Gigaspora) in the spore community and Gigaspora within the roots. Nitrogen enrichment also enhanced the proliferation of potentially less mutualistic species of Glomus. Autoregressive models implied that such patterns will persist and be driven by soil nitrogen cycling patterns. Chronic nitrogen enrichment from air pollution thus alters the diversity and mutualistic functioning of AM communities, which, in turn, may influence the plant community.

Ecosystem↗
PubMed1995

Simulation of the uptake of a reactive gas in a rat respiratory tract model with an asymmetric tracheobronchial region patterned on complete conducting airway cast data.

Generally, the uptake of reactive gases by the respiratory tract is simulated assuming that all paths from the trachea to the most distal airspaces are equivalent. As this is not the case, especially for nonhumans, the adequacy of this approach to predict doses that can be useful in the fields of toxicology and risk assessment is subject to question. To explore this issue, a dosimetry model is developed which combines the use of one-dimensional convection-dispersion equations in conjunction with multiple path anatomic models so that the dosimetry model simultaneously simulates transport and uptake in all the airways and airspaces of the anatomic model. For this work, the anatomic model of the tracheobronchial (TB) region is patterned on cast data which describe the dimensions and branching network of the 4807 airways of the TB region of a rat. Distal to each of the 2404 terminal bronchioles of the anatomical model, the air space is modeled as a single path. The results presented are preliminary; they focus on the predictions themselves to obtain an understanding of what the model has to say about uptake in a complex set of branching airways. Results include the following predictions: (1) Regardless of path there is a similarity along different paths in the shape of concentration profiles as well as a similarity in the shape of dose profiles. (2) Along a path in the TB or pulmonary region, dose decreases distally. (3) Generally, proximal alveolar region (PAR, a region of major morphological damage due to O3 and NO2) dose decreases the more distal the PAR. (4) There is considerable variation in the doses of the different airways or alveolar surfaces in the same generation. (5) The maximum and minimum PAR doses do not correspond to paths with, respectively, the smallest and largest number of generations from the trachea to the PAR. (6) The ratio of the maximum to minimum PAR dose is very sensitive to tidal volume. These results give a more realistic understanding of respiratory tract gas transport and uptake. The model also predicts aspects that equivalent path models cannot, such as the dose distribution of different but morphologically equivalent sites.

Algorithms↗
PubMed1995

Sarcoid myopathy in a patient with human immunodeficiency virus infection.

Although neither sarcoidosis nor HIV infection is rare, only eight patients with both diseases have been described. None of the eight had sarcoid myopathy. We describe a patient who had HIV infection and decreased CD4+ T-lymphocytes as well as sarcoidosis with muscle involvement. During 3 years of observation, primary sarcoidosis remitted and myopathic symptoms were controlled with prednisone. No opportunistic infections occurred during more than 3 years of prednisone therapy.

Adult↗
PubMed1995

Predisposing factors of systemic fungal infections of the genitourinary tract.

We reviewed 50 patients with genitourinary fungal infections between 1982 and 1992. Infections were classified as simple--localized to the bladder and complex--demonstrated evidence of upper tract and/or systemic infection. Predisposing factors of fungal infections, including diabetes mellitus, prolonged Foley catheter drainage and corticosteroid use, were not significantly different. The incidence of obstructive uropathy (88% versus 20%), malnutrition (88% versus 48%), neoplasia (56% versus 16%), renal failure (24% versus 8%) and prolonged antibiotic use (60% versus 32%) were significantly greater in patients with complex infections. The incidence of fungemia in patients with complex infections was 81% with an associated mortality rate of 36%. Of the patients with complex infections 56% required urological intervention. Given the high incidence of obstructive uropathy with complex fungal infections, upper tract imaging is essential.

Adolescent↗
PubMed1994

Effect of corticosteroid therapy on human immunodeficiency virus-associated nephropathy.

PURPOSE: Human immunodeficiency virus-associated nephropathy (HIV-AN) occurs predominantly in blacks and is characterized histologically by focal segmental glomerulosclerosis or mesangial proliferation and a lymphohistiocytic tubulointerstitial infiltrate. Patients manifest heavy proteinuria and, once azotemia occurs, progress rapidly to end-stage renal disease within 2 to 6 months. No treatment has been shown to be useful for HIV-AN. The purpose of this study was to determine the effect of corticosteroid agents on the progression of HIV-AN. PATIENTS AND METHODS: Four consecutive HIV-infected adults with fewer than 200 CD4 cells/microL, moderate to severe renal insufficiency, proteinuria greater than 2 g per 24 hours, and HIV-AN demonstrated by renal biopsy were treated with 60 mg of prednisone daily for 2 to 6 weeks. Patients were followed with respect to serum creatinine level, 24-hour protein excretion, adverse drug reactions, and the occurrence of opportunistic infections. RESULTS: CD4 counts ranged from 30 to 80 cells/microL before therapy with steroids. The mean (+/- SD) pretreatment serum creatine concentration was 9.1 +/- 5.7 mg/dL and decreased to 3.3 +/- 1.8 mg/dL (P < 0.05) after 2 to 6 weeks of corticosteroid therapy. Twenty-four hour protein excretion did not change (5.2 +/- 2.4 g pretreatment versus 4.6 +/- 4.1 g posttreatment). One patient was able to discontinue dialysis after 10 days. Two patients developed Mycobacterium avium-complex infections and steroid-associated psychosis. One of these patients developed a recurrence of genital herpes, and the other developed dermatomal zoster. None of the four required dialysis during a 1.5- to 5.5-month period of follow-up after cessation of steroid treatment. CONCLUSION: In selected patients with HIV-AN, short-term treatment with corticosteroid agents improves renal function and prevents the development of end-stage renal disease during a 1.5- to 5.5-month period of observation, but may be associated with an increased risk of opportunistic infection.

Adult↗
PubMed1993

Radon progeny dosimetry in the rat lung.

Deposition, mucociliary clearance, and dosimetry for the inhalation of radon progeny in the rat lung have been simulated for a variety of inhalation conditions. Computations indicate that the exposure-dose conversion factor for the rat lung is approximately twice as high as the corresponding value for the human lung for the same exposure conditions. However, if typical aerosol characteristics are used for animal inhalation experiments and human indoor exposures, the resulting exposure-dose conversion factors are comparable, thereby suggesting similar lung cancer risks per unit exposure. The predicted relative effects of radon progeny disequilibrium and unattached fractions on bronchial doses agree with results from inhalation experiments with laboratory rats.

Administration, Inhalation↗
PubMed1989

Predictions of ozone absorption in human lungs from newborn to adult.

Although children are an important human population, dosimetry models for gases have been used to predict absorption mainly in laboratory animals and adult humans. To correct this omission, we have used several sources of data on age-dependent lower respiratory tract (LRT) volumes, age-dependent airway dimensions, a model of the adult tracheobronchial region, and a model of the adult acinus to construct theoretical LRT lung models for humans from birth to adulthood. An ozone (O3) dosimetry model was then used to estimate the regional and local uptake of O3 in the (theoretical) LRT of children and adults. For sedentary or quiet breathing, the LRT distribution of absorbed O3, the percent uptake (84 to 88%) and the centriacinar O3 tissue dose are not very sensitive to age. For maximal work during exercise, predicted LRT uptakes range from 87 to 93%, and the regional percent uptakes are more dependent on age than during quiet breathing. In general, the total quantity of O3 absorbed per minute increases with age. Regardless of age and state of breathing, the largest tissue dose of O3 is predicted to occur in the centriacinar region, where many animal studies show the maximal morphological damage from O3.

Absorption↗
PubMed1989

Human subject age and activity level: factors addressed in a biomathematical deposition program for extrapolation modeling.

A deterministic aerosol deposition model, previously validated by data from adult inhalation exposure experiments, is used to study particle deposition within the developing human lung. Here, two age-dependent lung morphologies are presented, in which the number of tracheobronchial (TB) generations is complete at birth but airway dimensions vary with age; the number of pulmonary (P) generations, however, changes with age, as do the alveolated airway dimensions. Deposition patterns within the two morphologies are compared. For the light and heavy respiratory-activity levels considered, regional TB and P, and total (TB + P) lung deposition fractions are calculated. For all particle sizes (0.2-9.0 microns diameters) tested, total deposition in both morphologies was minimal for the 30-y-old adult and maximal for either of the youngest subjects (7 and 22 mo old). A breakdown of total deposition into lung compartments was specifically addressed for one morphological model. Age-dependent deposition models are intended to aid in future extrapolation efforts to assess the threat to human health from airborne contaminants.

Adult↗
PubMed1987

A model of the regional uptake of gaseous pollutants in the lung. II. The sensitivity of ozone uptake in laboratory animal lungs to anatomical and ventilatory parameters.

An O3 dosimetry model is used to simulate the local absorption of O3 in the lower respiratory tract of rats and guinea pigs. The model takes into account lower respiratory tract anatomy, transport in the lumen and air spaces, and transport and chemical reactions in the mucous and surfactant layers and in the underlying tissue and capillaries. For each species two anatomical models were used to investigate their influence in predicting absorption. Results with all four anatomical models and various ventilatory parameters showed a qualitative similarity in the shape of the dose versus airway number curves but significant differences in predicted percentage total and percentage pulmonary uptake. The percentage uptake was also sensitive to breathing frequency and tidal volume. Rat lobe models were used to study absorption in lobes and show that O3 tissue dose in centriacinar regions decreases with increasing distance from the trachea. The effect on results of values used for functional residual capacity and of values used for the chemical rate constants for O3 reactions in mucous were explored. Results differed quantitatively but not qualitatively.

Air Pollutants↗