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R Amonette

Publications and source records attributed to R Amonette.

10 recordsLinked to original sources
PubMed2004

Microbial community structure and oxidative enzyme activity in nitrogen-amended north temperate forest soils.

Large regions of temperate forest are subject to elevated atmospheric nitrogen (N) deposition which can affect soil organic matter dynamics by altering mass loss rates, soil respiration, and dissolved organic matter production. At present there is no general model that links these responses to changes in the organization and operation of microbial decomposer communities. Toward that end, we studied the response of litter and soil microbial communities to high levels of N amendment (30 and 80 kg ha(-1) yr(-1)) in three types of northern temperate forest: sugar maple/basswood (SMBW), sugar maple/red oak (SMRO), and white oak/black oak (WOBO). We measured the activity of extracellular enzymes (EEA) involved directly in the oxidation of lignin and humus (phenol oxidase, peroxidase), and indirectly, through the production of hydrogen peroxide (glucose oxidase, glyoxal oxidase). Community composition was analyzed by extracting and quantifying phospholipid fatty acids (PLFA) from soils. Litter EEA responses at SMBW sites diverged from those at oak-bearing sites (SMRO, BOWO), but the changes were not statistically significant. For soil, EEA responses were consistent across forests types: phenol oxidase and peroxidase activities declined as a function of N dose (33-73% and 5-41%, respectively, depending on forest type); glucose oxidase and glyoxal oxidase activities increased (200-400% and 150-300%, respectively, depending on forest type). Principal component analysis (PCA) ordinated forest types and treatment responses along two axes; factor 1 (44% of variance) was associated with phenol oxidase and peroxidase activities, factor 2 (31%) with glucose oxidase. Microbial biomass did not respond to N treatment, but nine of the 23 PLFA that formed >1 mol% of total biomass showed statistically significant treatment responses. PCA ordinated forest types and treatment responses along three axes (36%, 26%, 12% of variance). EEA factors 1 and 2 correlated negatively with PLFA factor 1 ( r = -0.20 and -0.35, respectively, n = 108) and positively with PLFA factor 3 ( r = +0.36 and +0.20, respectively, n = 108). In general, EEA responses were more strongly tied to changes in bacterial PLFA than to changes in fungal PLFA. Collectively, our data suggests that N inhibition of oxidative activity involves more than the repression of ligninase expression by white-rot basidiomycetes.

Analysis of Variance↗
PubMed2000

The use of imiquimod 5% cream for the treatment of superficial basal cell carcinomas in a basal cell nevus syndrome patient.

BACKGROUND: Imiquimod 5% cream has been used effectively to treat superficial basal cell carcinomas (BCCs). OBJECTIVE: The purpose of this study is to examine the effectiveness, tolerability, and desirability of imiquimod 5% cream in treating superficial non-facial basal cell carcinomas in a patient with basal cell nevus syndrome. METHODS: Three biopsy-proven nonfacial BCCs were treated for 18 weeks with once daily application of 5% imiquimod cream. The lesions were then removed to search histologically for residual tumor. RESULTS: The two adequately treated tumors revealed no residual BCC upon removal. Our patient reported that he tolerated the treatment but he would not desire this treatment again based on the length of treatment time and the degree of local inflammation at the treatment sites. CONCLUSION: Imiquimod 5% cream appears to be effective in eradicating superficial nonfacial BCCs. The degree of local inflammatory response may affect the patients' tolerability of treatment and therefore patient compliance.

Adjuvants, Immunologic↗
PubMed1999

Microcystic adnexal carcinoma: collaborative series review and update.

BACKGROUND: Microcystic adnexal carcinoma (MAC) is a malignant appendageal tumor first described in 1982. It can be clinically and histologically confused with other malignant and benign cutaneous neoplasms, leading to inadequate initial treatment. This neoplasm is locally aggressive and deeply infiltrating, characterized by high morbidity and frequent recurrence. Mohs micrographic surgery has been used to conserve tissue and improve the likelihood for cure. OBJECTIVE: We report our experience using Mohs micrographic surgery for the treatment of MAC and compare with earlier reports in the literature. In addition, we review the epidemiology, clinical and histologic characteristics, and optimal treatment of this rare neoplasm. We also describe a 15-year-old white male patient with MAC on the scalp occurring only 7 years after radiation exposure. METHODS: The medical records of 11 patients with MAC who were treated by Mohs micrographic surgery were reviewed at both departments, and follow-up data were obtained. RESULTS: In all patients treated with Mohs micrographic surgery, there were no recurrences after a mean follow-up of 5 years. CONCLUSION: Mohs technique enables the detection of clinically unrecognizable tumor spread and perineural invasion often encountered with MAC. Aggressive initial treatment by microscopically controlled excision appears to offer the greatest likelihood of cure for this neoplasm, while providing conservation of normal tissue. In addition, we describe the second youngest patient with MAC and readdress the issue of previous radiotherapy as an important predisposing factor.

Adolescent↗
PubMed1996

Melanoma awareness and self-examination practices: results of a United States survey.

BACKGROUND: Skin cancers are common and there has been a dramatic increase in their incidence, particularly melanoma. However, little is known about awareness of melanoma and early detection practices in the general U.S. population. OBJECTIVE: In 1995, the American Academy of Dermatology increased their efforts to promote awareness of melanoma. This study was conducted to document current knowledge of melanoma and self-examination practices. METHODS: In February 1995, a telephone survey was conducted in a nationally representative sample of 1001 persons at least 18 years of age (3% margin of error) that included questions on knowledge, attitudes, and practices regarding early detection of melanoma. RESULTS: Almost 42% of those surveyed were unaware of melanoma, and only 26% of those who were aware could identify its specific signs. Most recognized at least one common risk factor for melanoma (e.g., sun exposure, fair skin). However, many did not distinguish melanoma from other skin cancers in terms of risk factors, signs of early disease, and body site distribution. The lowest measures of melanoma knowledge and attitudes were found among those who are male, nonwhite, and parents, and those with the lowest level of education and income. More than half (54%) did not conduct a self-examination. This practice was most frequently reported by women, white persons, and the elderly, as well as those with a greater knowledge of melanoma. CONCLUSION: Our research documents deficiencies in knowledge and practices related to early detection of melanoma in the general U.S. population and supports the need for public education about melanoma.

Adult↗
PubMed1995

Principles of management of basal and squamous cell carcinoma of the skin.

There are a number of options available to the physician for the primary management of basal cell and squamous cell carcinoma of the skin. The most commonly used treatment modalities are primary resection, radiation therapy, and Mohs' micrographic surgery. Although each of these modalities can be used to treat most skin cancers in a variety of settings, each of these forms of cancer treatment is more appropriate in some settings and less appropriate in others. The role of each mode of therapy is discussed, based on effectiveness for cure, short and long term side effects, and cost of treatment. The appropriate role of the physician treating skin carcinoma is to choose the most effective treatment based on the above criteria and not to make the tumor fit any particular treatment modality.

Basal Cell Carcinoma↗