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Biomedical subjects

R O Peterson

Publications and source records attributed to R O Peterson.

10 recordsLinked to original sources
PubMed2001

Mercury concentrations in deer mouse (Peromyscus maniculatus) tissues from Isle Royale National Park.

We used deer mice (Peromyscus maniculatus) to investigate variation in mercury exposure across the terrestrial ecosystem of Isle Royale National Park (Michigan, USA). Although previous work suggested that mercury (Hg) levels may be higher inside the Sargent Lake watershed of Isle Royale than outside the watershed, Hg concentrations in livers were higher outside the Sargent Lake watershed (100.13 ng Hg/g dry tissue) than inside the watershed (35.50 ng Hg/g dry tissue; P = 0.06). Mercury levels in kidneys did not differ significantly (P = 0.57) between samples collected outside (443.23 ng Hg/g dry tissue) and inside (360.62 ng Hg/g dry tissue) the Sargent Lake watershed. Mean Hg concentrations in the livers of mice at some sites in Isle Royale are not significantly lower (P = 0.62) than Hg concentrations considered by some government agencies to be unhealthy for human consumption. Although Hg concentrations in mouse tissues were not remarkably high (compared to heavily polluted sites), concern is warranted because: (1) Isle Royale National park is a protected area in a remote location; (2) any exposure in deer mice represents a path for biomagnification in the terrestrial food web; and (3) the source of this mercury remains unidentified.

Animals↗
PubMed2001

Genetic (RAPD) diversity in Peromyscus maniculatus populations in a naturally fragmented landscape.

We assessed the effects of long-term habitat fragmentation on genetic (random amplified polymorphic DNA) diversity in 11 Peromyscus maniculatus populations in the Lake Superior watershed. We analysed genetic structure at two spatial scales and the effect of island size and isolation on genetic diversity. At the regional scale, island populations differed from mainland populations (FST = 0.36), but mainland populations did not differ from each other (FST = 0.01). At the local scale, populations of the main island of Isle Royale differed from adjacent islet populations (P < 0.001; Monte Carlo approximation of Fisher's exact test), but not from each other (combined P = 0.63). Although geographical distance and genetic distance were positively correlated (P < 0.01; Mantel test), cluster analysis revealed some inconsistencies. Finally, genetic diversity was inversely related to isolation (P = 0.01), but had an unexpectedly negative relationship with island area (P = 0.03). The genetic structure of P. maniculatus populations in portions of the Lake Superior watershed appears to have been affected by long-term habitat fragmentation.

Animals↗
PubMed1996

Osteoporotic skull lesions in moose at Isle Royale National Park.

Osteoporotic lesions were evaluated in the skulls of moose (Alces alces) collected in Isle Royale National Park, Michigan (USA), from 1958 to 1994. Circular lesions which penetrated the outer table of the skull were distributed over the frontal and nasal bones asymmetrically in both sexes. About 32% of skulls recovered had some porotic lesions with slightly greater prevalence among males.

Animals↗
PubMed1991

Differences in urinary chemistry profiles of moose on Isle Royale during winter.

During winters 1987-1988 (I) and 1988-1989 (II), we assessed the physiological status of moose (Alces alces) residing on the west and east ends of Isle Royale (Michigan, USA) by collecting and chemically analyzing urine deposited in snow (snow-urine) from January to early March. Samples were assayed for urea nitrogen (U), sodium (Na), potassium (K), calcium (Ca), phosphorus (P) and creatinine (C). Throughout both winters, elevated urinary U:C ratios in snow-urine samples collected from east-end moose compared to west-end moose indicated greater dietary energy deprivation and accelerated net catabolism of endogenous protein. Sodium: C ratios were low throughout the study and were similar between moose from both ends of the island, except during the middle of winter I. Greater K:C, P:C and Ca:C ratios in east-end moose compared to west-end moose throughout winter I, and increases in these ratios and U:C in east-end moose from middle to late winter during the second year provided additional evidence of a greater deterioration in condition in east-end moose. The superior nutrition provided to moose on the west end of the island was associated with more developed soils and diverse vegetation and a lower stem density of balsam fir compared to the east end.

Animal Nutritional Physiological Phenomena↗
PubMed1990

Renal vein leiomyosarcoma.

The 11th case of primary leiomyosarcoma of the renal vein is reported. Unique features of this case included concomitant resection of an isolated hepatic metastasis, intraoperative radiation therapy, and the use of electron microscopy and immunohistochemical stains in confirming the diagnosis. A review of the previously reported cases shows a tendency toward slow tumor growth and infrequent recurrence (18%). Metastases are common (82%), primarily to the lung and liver. Aggressive surgical resection and adjuvant radiation therapy, including intraoperative radiation therapy, are recommended. Adjuvant chemotherapy should be considered, although its benefits at present are unclear.

Adult↗
PubMed1989

Cause of death in carcinoma of the esophagus.

Carcinoma of the esophagus continues to carry a very poor prognosis. Previous studies have rarely reported the exact cause of death in these patients. Twenty-five autopsies were retrospectively reviewed in patients with the diagnosis of carcinoma of the esophagus, noting the cause of death. Two-thirds of all patients with unresected middle-third lesions ultimately died as a result of direct extension of the tumor into the aorta or tracheobronchial tree. Other findings included a high incidence of second neoplasms (12%) and the lack of an antemortem diagnosis of esophageal cancer in three of four females in the series.

Aged↗
PubMed1988

Increased osteoarthritis in moose from Isle Royale.

Over the past 30 yr, moose (Alces alces) in Isle Royale National Park (Michigan, USA) exhibited a several-fold increase in the prevalence of osteoarthritis, or degenerative joint disease (DJD). Available evidence points to an environmental explanation for this change. Greater physical activity among afflicted moose is not a likely contributing factor, nor is genetic change in the population. The possible introduction of an unspecified disease agent cannot be dismissed at this time. Moose exhibiting the highest prevalence of DJD were those born during a period of severe undernutrition, and it is hypothesized that nutritional stress early in life was responsible for increased joint disease during senescence. Such an etiology for osteoarthritis has not been suggested previously for any species.

Animals↗
PubMed1985

Carfentanil and xylazine for immobilization of moose (Alces alces) on Isle Royale.

Twenty-one moose were captured on Isle Royale between 28 May and 2 June 1984 at licks on the western end of the island. The animals were darted, at ranges of 10 to 35 m, with 3-cc dart syringes containing 3 or 4 mg of carfentanil and 100 or 175 mg of xylazine. Three animals were drugged with carfentanil alone. Immobilization time ranged from 2.5 to 6 min. There was no excitement phase evident in 18 of the animals and they rarely moved more than 30 m after darting. Reversal was begun at 30 to 90 min after darting using naloxone and diprenorphine given intramuscularly (i.m.) and intravenously (i.v.). Recovery time varied from 10 min to 3 hr with the longer times occurring at the higher doses of immobilizing drugs. Two animals died within 30 hr, one as the result of aspiration of rumen contents and the other was unable to get on its feet and was euthanized. Analysis of blood samples from the 18 moose immobilized with the drug combination yielded hemoglobin values of 13.1 +/- 0.3 g/dl, hematocrit: 37.6 +/- 0.7%, red blood cells: 5.46 +/- 0.1 million/microliter, leucocytes: 6.1 +/- 0.4 thousand/microliter, and serum urea nitrogen: 29.3 +/- 1.6 mg/dl. Our experience indicated that quiet, undisturbed moose can be immobilized with 3 mg carfentanil and 100 mg or less of xylazine.

Animals↗