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Biomedical subjects

Jennifer L Troyer

Publications and source records attributed to Jennifer L Troyer.

9 recordsLinked to original sources
PubMed2006

Neurologic disease in captive lions (Panthera leo) with low-titer lion lentivirus infection.

Lion lentivirus (LLV; also known as feline immunodeficiency virus of lion, Panthera leo [FIVPle]) is present in free-ranging and captive lion populations at a seroprevalence of up to 100%; however, clinical signs are rarely reported. LLV displays up to 25% interclade sequence diversity, suggesting that it has been in the lion population for some time and may be significantly host adapted. Three captive lions diagnosed with LLV infection displayed lymphocyte subset alterations and progressive behavioral, locomotor, and neuroanatomic abnormalities. No evidence of infection with other potential neuropathogens was found. Antemortem electrodiagnostics and radiologic imaging indicated a diagnosis consistent with lentiviral neuropathy. PCR was used to determine a partial lentiviral genomic sequence and to quantify the proviral burden in eight postmortem tissue specimens. Phylogenetic analysis demonstrated that the virus was consistent with the LLV detected in other captive and free-ranging lions. Despite progressive neurologic signs, the proviral load in tissues, including several regions of the brain, was low; furthermore, gross and histopathologic changes in the brain were minimal. These findings suggest that the symptoms in these animals resulted from nonspecific encephalopathy, similar to human immunodeficiency virus, FIV, and simian immunodeficiency virus (SIV) neuropathies, rather than a direct effect of active viral replication. The association of neuropathy and lymphocyte subset alterations with chronic LLV infection suggests that long-term LLV infection can have detrimental effects for the host, including death. This is similar to reports of aged sootey mangabeys dying from diseases typically associated with end-stage SIV infection and indicates areas for further research of lentiviral infections of seemingly adapted natural hosts, including mechanisms of host control and viral adaptation.

Animals↗
PubMed2006

Environmental contexts of ultimate decisions: why White nursing home residents are twice as likely as African American residents to have an advance directive.

OBJECTIVES: The purpose of this study was to determine the extent to which observed differences between White and African American nursing home residents in having an advance directive are attributable to differences between the groups in personal characteristics, the organizational environment of the nursing home, and the geographical environment of the counties in which the nursing homes are located. METHODS: By using the Medical Expenditure Panel Survey Nursing Home Component matched with county-level measures from the Area Resource File, we modeled the probability of having an advance directive as a function of nursing home resident, facility, and county characteristics for African American and White residents. RESULTS: The probability of having an advance directive was 27.0% for African American residents and 63.6% for White residents. Nearly half of this 36.6 percentage point gap could be explained by group differences in personal, facility, and county characteristics. DISCUSSION: County characteristics play a more prominent role than do personal or facility measures in explaining the observed ethnic gap in the prevalence of advance directives. Additional studies should focus further on geographic, health status, and attitudinal variations among nursing home residents that may account for the remaining ethnic difference in the prevalence of advance directives among nursing home residents.

Advance Directives↗
PubMed2005

Feline lentiviruses demonstrate differences in receptor repertoire and envelope structural elements.

Feline immunodeficiency virus (FIV) causes fatal disease in domestic cats via T cell depletion-mediated immunodeficiency. Pumas and lions are hosts for apparently apathogenic lentiviruses (PLV, LLV) distinct from FIV. We compared receptor use among these viruses by: (1) evaluating target cell susceptibility; (2) measuring viral replication following exposure to specific and non-specific receptor antagonists; and (3) comparing Env sequence and structural motifs. Most isolates of LLV and PLV productively infected domestic feline T cells, but differed from domestic cat FIV by infecting cells independent of CXCR4, demonstrating equivalent or enhanced replication following heparin exposure, and demonstrating substantial divergence in amino acid sequence and secondary structure in Env receptor binding domains. PLV infection was, however, inhibited by CD134/OX40 antibody. Thus, although PLV and LLV infection interfere with FIV superinfection, we conclude that LLV and PLV utilize novel, more promiscuous mechanisms for cell entry than FIV, underlying divergent tropism and biological properties of these viruses.

Amino Acid Sequence↗
PubMed2005

Seroprevalence and genomic divergence of circulating strains of feline immunodeficiency virus among Felidae and Hyaenidae species.

Feline immunodeficiency virus (FIV) infects numerous wild and domestic feline species and is closely related to human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV). Species-specific strains of FIV have been described for domestic cat (Felis catus), puma (Puma concolor), lion (Panthera leo), leopard (Panthera pardus), and Pallas' cat (Otocolobus manul). Here, we employ a three-antigen Western blot screening (domestic cat, puma, and lion FIV antigens) and PCR analysis to survey worldwide prevalence, distribution, and genomic differentiation of FIV based on 3,055 specimens from 35 Felidae and 3 Hyaenidae species. Although FIV infects a wide variety of host species, it is confirmed to be endemic in free-ranging populations of nine Felidae and one Hyaenidae species. These include the large African carnivores (lion, leopard, cheetah, and spotted hyena), where FIV is widely distributed in multiple populations; most of the South American felids (puma, jaguar, ocelot, margay, Geoffroy's cat, and tigrina), which maintain a lower FIV-positive level throughout their range; and two Asian species, the Pallas' cat, which has a species-specific strain of FIV, and the leopard cat, which has a domestic cat FIV strain in one population. Phylogenetic analysis of FIV proviral sequence demonstrates that most species for which FIV is endemic harbor monophyletic, genetically distinct species-specific FIV strains, suggesting that FIV transfer between cat species has occurred in the past but is quite infrequent today.

Amino Acid Sequence↗
PubMed2005

Medicaid enrollee switching among managed care plans.

This case-study (n=41,969) of voluntary switching among Mecklenburg County, North Carolina Medicaid managed care plans showed a low switching rate of 14.5 per 100 member-years over 33 months, or 5.3 averaged annually. Population, plan and plan characteristics, claims and telephone survey data were examined to better understand this important behavioral measure. Switching in Medicaid managed care, which is little studied, is contrasted with the extensive literature on middle class switching. Policy implications included the suitability of Medicaid populations for managed care and the need for more research on switching and disenrollment and the Medicaid innovation of neutral health benefits advising.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed2004

Examining differences in death rates for medicaid and non-medicaid nursing home residents.

OBJECTIVES: The purpose of this work was to examine differences in the probability of death for Medicaid and privately funded nursing home residents, controlling for differences in facility, market, and resident characteristics. METHODS: Given that Medicaid residents are more likely to die in nursing facilities, the probability of dying within 1 or 2 years is estimated using a series of probit models, controlling for whether a resident is Medicaid-funded or privately-funded. As resident characteristics, market attributes, facility characteristics, and facility fixed effects are sequentially added to the specifications, the gap in the probability of death between Medicaid and private-pay residents is considered. RESULTS: The overall mortality rate for Medicaid residents was 14.8% points higher than the death rate for privately funded residents. When considering death within 1 year and 2 years, Medicaid resident death rates were 4.2% and 7.8% higher, respectively. The apparent difference in mortality declines as one controls for resident, market, and facility characteristics. Both facility characteristics and facility fixed effects are relatively important in explaining differences in death rates between Medicaid and private-pay residents. CONCLUSIONS: Differences in death rates between Medicaid and private-pay residents are relatively small, suggesting that residents with different payment sources are not treated differently in nursing homes in ways that impact the probability of death. However, policymakers may want to look more closely at whether Medicaid residents are segregated into lower-quality facilities.

Age Factors↗
PubMed2004

Patterns of feline immunodeficiency virus multiple infection and genome divergence in a free-ranging population of African lions.

Feline immunodeficiency virus (FIV) is a lentivirus that causes AIDS-like immunodeficiency disease in domestic cats. Free-ranging lions, Panthera leo, carry a chronic species-specific strain of FIV, FIV-Ple, which so far has not been convincingly connected with immune pathology or mortality. FIV-Ple, harboring the three distinct strains A, B, and C defined by pol gene sequence divergences, is endemic in the large outbred population of lions in the Serengeti ecosystem in Tanzania. Here we describe the pattern of variation in the three FIV genes gag, pol-RT, and pol-RNase among lions within 13 prides to assess the occurrence of FIV infection and coinfection. Genome diversity within and among FIV-Ple strains is shown to be large, with strain divergence for each gene approaching genetic distances observed for FIV between different species of cats. Multiple in fections with two or three strains were found in 43% of the FIV-positive individuals based on pol-RT sequence analysis, which may suggest that antiviral immunity or interference evoked by one strain is not consistently protective against infection by a second. This comprehensive study of FIV-Ple in a free-ranging population of lions reveals a dynamic transmission of virus in a social species that has historically adapted to render the virus benign.

Amino Acid Sequence↗
PubMed2004

The impact of litigation on nursing home quality.

Government reports indicate that regulations have been ineffective in improving quality of care in many nursing homes. Some analysts feel that litigation against nursing homes may be the result of quality problems that are monitored during the inspection process, some contend litigation merely causes quality problems by diverting financial resources away from patient care, and some argue that litigation is duplicating the efforts of the inspection process. Given that the relationship between litigation and inspection-oriented measures of quality is not clear, this article explores the relationship empirically. When a significant relationship is found, the empirical results suggest that litigation is associated with a decline in inspection-oriented measured quality in the nursing home facing the legal claim. In contrast, litigation against a chain has a very different relationship to firm-level quality, where firms within a chain that is being sued have higher levels of inspection-oriented quality. Our results suggest that legal claims may result from quality problems that go unmeasured during the inspection process. However, more research in this area is warranted.

Aged↗