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Biomedical subjects

L J Lowenstine

Publications and source records attributed to L J Lowenstine.

At least 19 recordsLinked to original sources
PubMed2000

Mortality of sea lions along the central California coast linked to a toxic diatom bloom.

Over 400 California sea lions (Zalophus californianus) died and many others displayed signs of neurological dysfunction along the central California coast during May and June 1998. A bloom of Pseudo-nitzschia australis (diatom) was observed in the Monterey Bay region during the same period. This bloom was associated with production of domoic acid (DA), a neurotoxin that was also detected in planktivorous fish, including the northern anchovy (Engraulis mordax), and in sea lion body fluids. These and other concurrent observations demonstrate the trophic transfer of DA resulting in marine mammal mortality. In contrast to fish, blue mussels (Mytilus edulus) collected during the DA outbreak contained no DA or only trace amounts. Such findings reveal that monitoring of mussel toxicity alone does not necessarily provide adequate warning of DA entering the food web at levels sufficient to harm marine wildlife and perhaps humans.

Animals↗
PubMed1999

Endothelial cell changes are associated with pulmonary edema and respiratory distress in mice infected with the WA1 human Babesia parasite.

A C3H/HeN mouse model was established to study the pathogenesis of the human babesial parasites, WA1 and Babesia microti. To evaluate the course of parasitemia and the associated lesions, mice were inoculated intraperitoneally with either WA1-infected, B. microti-infected, or uninfected hamster red blood cells. WA1-infected mice developed dyspnea and moderate parasitemias, after which death occurred. Babesia microti-infected mice experienced low parasitemias with no apparent morbidity or mortality. WA1-infected mice were thrombocytopenic but not anemic. Hemograms for B. microti-infected mice were similar to controls. Postmortem examination of WA1-infected mice revealed prominent lesions in the lungs, including pulmonary edema and intravascular margination of leukocytes. No pulmonary changes were detected in B. microti-infected mice. Blood gas measurements of WA1-infected mice showed reduced oxygen saturation and pH, and increased carbonic acid compared to controls, indicating hypoxia and respiratory acidosis. Ultrastructure studies of WA1-infected lungs showed hypertrophied endothelial cells containing transcellular channels associated with protein-rich intra-alveolar fluid. Endothelial cell activation was demonstrated by an upregulation of intercellular adhesion molecule-1 in the lungs of WA1-infected mice. The results suggest that recruitment of inflammatory cells to the lungs in WA1-infected mice induces endothelial cell alterations, leading to pulmonary edema and acute respiratory failure.

Animals↗
PubMed1999

Capillaria hepatica (Nematoda) infections in human-habituated mountain gorillas (Gorilla gorilla beringei) of the Parc National de Volcans, Rwanda.

Habituation to humans of free-ranging populations of endangered mountain gorillas (Gorilla gorilla beringei) raised concern of anthropozoonotic transmission of parasitic helminths and protozoans. Examinations of liver tissue of 19 gorillas found dead in the Parc National de Volcans, Rwanda, revealed 10 cases of hepatic nematodiasis due to Capillaria hepatica. Identifiable C. hepatica eggs were present in the liver of 4 gorillas (3 juveniles, 1 adult), and nematode cross-sections were found in 1 juvenile gorilla. Six other adult gorillas had areas of periportal and subcapsular fibrosis with calcified eggs. Histologically, the lesions surrounded by the areas of mild inflammatory reaction were characterized by subcapsular, periportal foci of fibrosis in which were embedded numerous C. hepatica eggs. Control of hepatic capillariasis in the remaining populations of mountain gorillas should be focused on eradication or control of populations of rodent pests (i.e., mice and rats) that sustain the reservoir of C. hepatica in habitats shared by gorillas and humans.

Animals↗
PubMed1998

Antigenic and nucleotide characterization of a herpesvirus isolated from Pacific harbor seals (Phoca vitulina richardsii).

This report describes the antigenic and nucleotide characterization of a herpes-like virus that has been isolated from the adrenal tissues of neonatal Pacific harbor seals. Infection with this virus has been previously implicated as a major cause of death of animals undergoing rehabilitation. Comparison and phylogenetic analysis of sequenced fragments of the DNA polymerase, glycoprotein B and glycoprotein D genes, and immunofluorescence assay using herpesvirus-specific monoclonal antibodies, demonstrated close similarity of the Pacific harbor seal herpesvirus to European isolates of phocid herpesvirus-1 (PHV-1) and other alpha-herpesviruses affecting terrestrial carnivores.

Adrenal Glands↗
PubMed1998

Bartonella henselae antibody prevalence in free-ranging and captive wild felids from California.

In order to determine the importance of wild felids in the epidemiology of Bartonella spp. infection, 136 Nobuto strips or serum samples from free-ranging mountain lions (Felis concolor) and bobcats (Felis rufus) captured in California (USA) between 1985 and 1996 were tested for B. henselae antibodies (titer > or = 1:64) using an immunofluorescence test. Similarly, 124 serum samples from 114 captive wild cats representing 26 species or subspecies collected between 1991 and 1995 were retrieved from the serum banks of four California zoological parks. Fifty-three percent (33/62) of the bobcats, 35% (26/74) of the mountain lions, and 30% (34/114) of the captive wild felids (genera Acinonyx, Panthera and Felis) had B. henselae antibodies. In captive wild felids, prevalence varied widely among the species, but seropositivity was more likely to occur in the genus Felis than in the genus Acinonyx or Panthera. Prevalence was evenly distributed between sexes, except for free-ranging mountain lions. Antibody prevalence ranged from 25% in 0- to 2-yr-old captive felids to 35% in cats > or = 9-yr-old, but the highest antibody titers were observed in cats < 5-yr-old.

Age Factors↗
PubMed1998

Meningoencephalitis due to a Sarcocystis neurona-like protozoan in Pacific harbor seals (Phoca vitulina richardsi).

Seven Pacific harbor seals with meningoencephalitis associated with Sarcocystis neurona-like protozoa are described. Six of the 7 seals were free-ranging and were found stranded over an 80-km stretch of central California coastline; the other was captive. All had marked to severe nonsuppurative meningoencephalitis, most severe in the cerebellar cortex. Immunohistochemistry for S. neurona antigens was positive on brain tissue in all cases, revealing numerous merozoites as well as developing and mature schizonts, including rosette forms. Electron microscopy performed on 3 animals revealed merozoites and schizonts consistent with Sarcocystis sp., with the absence of rhoptries in merozoites, lack of a parasitophorous vacuole around schizonts, and division by endopolygeny. Serology using western blotting revealed the presence of anti-S. neurona immunoglobulins in the sera of 4 of 5 seals tested. Four animals also had a concurrent mild to moderate nonsuppurative myocarditis; in 1 seal, rare sarcocysts of undetermined species were present within cardiomyocytes.

Animals↗
PubMed1997

Congenital defects in northern elephant seals stranded along the central California coast.

Eleven cases of congenital anomalies were identified in 210 (5%) juvenile northern elephant seals (Mirounga angustirostris) found stranded along the central California (USA) coast from 1 January 1988 to 31 December 1995. Seven individuals had mild-to-moderate hydrocephalus involving the lateral ventricles bilaterally, or the lateral and third ventricles. Two animals had severe cardiac anomalies: hypoplasia of the right ventricle with overriding aorta, and ventricular septal defect. Other anomalies included single cases of hydronephrosis, focal pulmonary dysplasia, and congenital epidermal angiomatosis. Common intercurrent disease processes were verminous pneumonia and arteritis, verminous enteritis and coliti, and splenic and hepatic hemosiderosis. The more severe anomalies were considered to be the cause of debilitation and stranding. Milder anomalies were found incidentally during routine gross necropsy and histopathologic examination.

Angiomatosis↗
PubMed1997

Clinical and pathological characterization of northern elephant seal skin disease.

From 1984 through 1992, staff at The Marine Mammal Center (TMMC, Sausalito, California, USA) examined 207 northern elephant seals (Mirounga angustirostris) with a condition of unknown etiology called northern elephant seal skin disease (NESSD). The skin lesions were characterized by patchy to extensive alopecia and hyperpigmentation, punctate or coalescing epidermal ulceration, and occasionally, massive skin necrosis. Microscopic lesions included ulcerative dermatitis with hyperkeratosis, squamous metaplasia and atrophy of sebaceous glands. All diseased seals were less than 2 years of age and suffered from emaciation, depression, and dehydration. Mortality from septicemia increased significantly with severity of skin ulceration. Compared to 14 apparently unaffected seals, diseased seals had depressed levels of circulating thyroxine, triiodothyronine, retinol, serum iron, albumin, calcium, and cholesterol. Levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, gamma glutamyl transpeptidase, blood urea nitrogen, and uric acid were elevated. Morphometrically, diseased animals were approximately 15% smaller than normal seals of the same sage. Serum and blubber concentrations of 36 polychlorinated biphenyl congeners (sigma PCB) and dichloro-diphenyl-dichloroethylene (p,p'-DDE) were negatively correlated with body mass. Mean concentrations of sigma PCB and p,p'-DDE in serum in diseased seals were elevated as compared to apparently normal seals. Etiology of this syndrome remains unknown, but the possibility of PCB toxicosis cannot be ruled out.

Alopecia↗
PubMed1997

Herpesvirus infection in stranded Pacific harbor seals of coastal California.

Histopathological examination revealed multifocal acute to chronic adrenal necrosis in 74 of 162 (45%) Pacific harbor seal pups (Phoca vitulina richardsi) dying during rehabilitation following live stranding along the coast of central and northern California (USA). Necrotic adrenal cells contained amphophilic, smudgy intranuclear inclusion bodies that were stained positive for DNA. Fifty of these seals also had lesions typical of sepsis, bacterial omphalophlebitis, pneumonia or gastroenteritis. Twenty four seals had no lesions other than thymic atrophy and occasional multifocal hepatic necrosis. Prior to death, affected seals had a marked lymphopenia. Electron microscopy revealed unenveloped intranuclear hexagonal to round viral particles approximately 100 nm in diameter, and cytoplasmic enveloped virions approximately 160 nm in diameter. These were morphologically consistent with herpesvirus. Inoculation of phocine adrenal and kidney cell lines with an adrenal tissue homogenate from affected animals produced a cytopathic effect in 5 days. Electron microscopy of cell cultures showing this cytopathic effect revealed similar viral particles to those observed in affected adrenal glands. Cases with characteristic inclusion bodies were observed in 42 of 95 (44%) male and 32 of 67 (47%) female seals. Affected animals had been in rehabilitation 0 to 63 days and were below average birth weight for this species.

Adrenal Cortex↗
PubMed1996

Metastatic carcinoma of probable transitional cell origin in 66 free-living California sea lions (Zalophus californianus), 1979 to 1994.

Sixty-six (18%) cases of widely metastatic carcinoma of probable transitional cell origin were identified in 370 California sea lions (Zalophus californianus) stranded alive along the central California (USA) coast, between January 1979 and December 1994. Live animals were usually emaciated and anorectic, with perineal edema and occasionally hind-flipper paralysis or paresis. Large yellow caseous masses were observed in the sub-lumbar lymph nodes, often extending around the ureters resulting in hydroureter. Histologically, metastases were usually widespread, and the primary neoplastic focus undetectable. This is the highest reported prevalence among necropsied animals of neoplasia in a pinniped population to date.

Age Determination by Teeth↗
PubMed1996

Herpesvirus particles associated with oral and respiratory lesions in a California desert tortoise (Gopherus agassizii).

A 60-year-old captive California desert tortoise (Gopherus agassizii) which died in August 1990 at the University of California, Davis, California (USA), during treatment for colonic impaction had marked caseous necrosis of the oral cavity, choana, trachea, and lungs. Numerous intranuclear inclusion bodies and a large number of syncytial giant cells were seen in the oral cavity and respiratory tract along with bacterial granulomas. Pasteurella testudinis, Streptococcus veridans, and coagulase-negative Staphilococcus spp. were cultured from the lesions. Using electron microscopy, herpesvirus particles were observed in intranuclear inclusions and cytoplasm. Viral stomatitis, tracheitis, and bronchopneumonia complicated by bacterial infection were diagnosed. Although respiratory disease is common in desert tortoises, this is believed to be the first report of association with a viral infection.

Animals↗
PubMed1996

Baseline coagulation assay values for northern elephant seals (Mirounga angustirostris), and disseminated intravascular coagulation in this species.

Coagulation assays, including platelet counts, antithrombin III, fibrinogen, fibrinogen degradation product levels, prothrombin (PT), activated partial thromboplastin (APTT) and activated clotting times (ACT), were performed on 20 healthy juvenile northern elephant seals (Mirounga angustirostris) stranded along the central California coastline from 15 March to 15 April 1994, to establish baseline parameters for this species. Elephant seals appear to have relatively short ACT, PT, and APTT times, while fibrinogen, platelet and antithrombin III levels are similar to domestic species. Based on these mean values in healthy animals, disseminated intravascular coagulation (DIC) was diagnosed in an elephant seal with low plasma fibrinogen and extended ACT, PT and APTT times; this animal had hemorrhages, mixed bacterial suppurative interstitial pneumonia with verminous arteritis, epicarditis, hepatitis and enterocolitis.

Animals↗
PubMed1996

Leptospirosis in California sea lions (Zalophus californianus) stranded along the central California coast, 1981-1994.

Prevalence of leptospirosis was determined in California sea lions (Zalophus californianus) stranded live along the central California (USA) coast between January 1981 and December 1994. Clinical signs of renal disease were seen in 764 (33%) of 2338 animals examined; 545 (71%) of these 764 animals died, with similar gross lesions of nephritis. In silver impregnation stains of sections of formalin-fixed kidney, numerous loosely coiled spiral organisms were observed. Leptospira pomona kenniwicki was cultured from four kidney samples in 1991. Epizootics of leptospirosis occurred in 1984, 1988, 1991, and 1994, and were more common in the autumn, typically affecting juvenile males. In 1991 and 1994, 47 animals sampled had antibody titers to L. pomona greater than 1:3200. In 1992, 20 animals sampled were seronegative, and in 1993 three of 20 animals sampled had low titers to L. pomona.

Animals↗
PubMed1996

Coccidioidomycosis in free-living California sea lions (Zalophus californianus) in central California.

Coccidioidomycosis is described in seven California sea lions (Zalophus californianus) admitted to The Marine Mammal Center, Sausalito, California (USA), between January 1986 and December 1994. Diagnoses were confirmed by histology in all seven cases, culture in three cases, and serology in one case. These are believed to be the first published cases of coccidioidomycosis in free-ranging California sea lions.

Animals↗
PubMed1996

Comparative pathogenesis of human WA1 and Babesia microti isolates in a Syrian hamster model.

The pathogenesis of a newly recognized, molecularly and antigenically distinct human babesial isolate (WA1) and Babesia microti, the common cause of human babesiosis in the United States, were compared in a Syrian hamster model. A group of 33 adult female hamsters were inoculated intraperitoneally with either WA1-infected, B. microti-infected, or uninfected hamster erythrocytes. All WA1-infected animals became parasitemic by postinoculation (PI) day 3 or 4 and were severely lethargic and dyspneic by PI days 6 to 10. Death often occurred spontaneously by PI day 10, with parasitemia of 12 to 90%. Hamsters inoculated with B. microti became parasitemic by PI day 7 and developed peak parasitemia (42 to 60%) by PI day 14 that subsequently decreased to low or undetectable values. Although the B. microti-infected hamsters developed severe anemia, they generally remained asymptomatic. Postmortem examination of WA1-infected hamsters revealed intravascular aggregates of large mononuclear inflammatory cells that occasionally occluded small to medium veins, pulmonary leukoclastic phlebitis, thrombosis, and multifocal coagulative necrosis in the heart, spleen, lung, and liver. No vascular lesions or areas of coagulative necrosis were detected in any B. microti-infected or control hamsters. The results of this study suggest that marked leukocytosis followed by acute necrotizing phlebitis resulting in disseminated intravascular coagulation, thromboembolism, and infarction may be central to the pathogenesis of WA1 infections.

Anemia↗
PubMed1995

A survey for selected viral, chlamydial, and parasitic diseases in wild dusky-headed parakeets (Aratinga weddellii) and tui parakeets (Brotogeris sanctithomae) in Peru.

Thirty-eight free-ranging dusky-headed parakeets (Aratinga weddellii) and 13 tui parakeets (Brotogeris sanctithomae) were caught and released in Parque Nacional del Manu in southeastern Peru from 19 July to 5 August 1993. Blood and fecal samples were collected and sera were evaluated for titers to Pacheco's disease herpesvirus, psittacine polyomavirus, paramyxovirus-1, and Chlamydia psittaci. Fecal samples were examined for evidence of ascarid or coccidial infection by fecal flotation, and blood smears were examined for hemoparasites. Five (50%) of 10 A. weddellii serum samples tested by complement fixation (CF) for psittacine polyomavirus antibodies were positive, and three (19%) of 16 A. weddellii samples tested by virus neutralization (VN) for psittacine polyomavirus antibodies were positive, yielding a total of 8 (38%) of the 21 A. weddellii samples positive for psittacine polyomavirus. Based on CF for herpesvirus, four (11%) of 38 A. weddellii samples had antibodies against herpesvirus. All B. sanctithomae were negative for psittacine polyomavirus and psittacine herpesvirus. Thirty-five of the A. weddellii tested were negative for Chlamydia psittaci by CF, latex agglutination, and elementary body agglutination, and all B. sanctithomae were negative for Chlamydia psittaci by the CF test. Nine A. weddellii and eight B. sanctithomae evaluated for paramyxovirus-1 titers by the hemagglutination inhibition test were negative. All fecal samples were negative for ascarids or coccidia by fecal flotation, and all blood smears were negative for hemoparasites by direct microscopic examination. This is the first known description of psittacine polyomavirus and psittacine herpesvirus in free-ranging parrots. Serologic evidence of Pacheco's disease herpesvirus in wild A. weddellii is interesting in light of the fact that Aratinga spp. are considered to be possible carriers of this virus in captivity.

Animals↗
PubMed1994

Apparent gossypol-induced toxicosis in adult dairy goats.

Consumption of a cotton-seed meal-based mineral supplement (cattle label) and a concentrate dairy mix (goat label) resulted in gossypol toxicosis in 3 adult dairy goats. The primary clinical signs were limb swelling and stiffness, ventral abdominal edema, and anorexia. All does died within a few days of the onset of illness. Necropsy revealed generalized subcutaneous edema, acute centrilobular necrosis of the liver, and myocardial fibrosis, consistent with a diagnosis of gossypol toxicosis. It was estimated that the does had consumed from 348 to 414 mg of free gossypol/d for at least 3 months. Apparent gossypol toxicosis in goats consuming this amount of free gossypol indicates that goats may be more susceptible than cattle to this substance.

Animal Feed↗