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Biomedical subjects

Larry E Davis

Publications and source records attributed to Larry E Davis.

16 recordsLinked to original sources
PubMed2006

West Nile virus neuroinvasive disease.

Since 1999, there have been nearly 20,000 cases of confirmed symptomatic West Nile virus (WNV) infection in the United States, and it is likely that more than 1 million people have been infected by the virus. WNV is now the most common cause of epidemic viral encephalitis in the United States, and it will likely remain an important cause of neurological disease for the foreseeable future. Clinical syndromes produced by WNV infection include asymptomatic infection, West Nile Fever, and West Nile neuroinvasive disease (WNND). WNND includes syndromes of meningitis, encephalitis, and acute flaccid paralysis/poliomyelitis. The clinical, laboratory, and diagnostic features of these syndromes are reviewed here. Many patients with WNND have normal neuroimaging studies, but abnormalities may be present in areas including the basal ganglia, thalamus, cerebellum, and brainstem. Cerebrospinal fluid invariably shows a pleocytosis, with a predominance of neutrophils in up to half the patients. Diagnosis of WNND depends predominantly on demonstration of WNV-specific IgM antibodies in cerebrospinal fluid. Recent studies suggest that some WNV-infected patients have persistent WNV IgM serum and/or cerebrospinal fluid antibody responses, and this may require revision of current serodiagnostic criteria. Although there is no proven therapy for WNND, several vaccines and antiviral therapy with antibodies, antisense oligonucleotides, and interferon preparations are currently undergoing human clinical trials. Recovery from neurological sequelae of WNV infection including cognitive deficits and weakness may be prolonged and incomplete.

Animals↗
PubMed2006

Immunohistochemical analysis of metastatic neoplasms of the central nervous system.

Metastatic neoplasms to the central nervous system are often encountered in the practice of surgical neuropathology. It is not uncommon for patients with systemic malignancies to present to medical attention because of symptoms from a brain metastasis and for the tissue samples procured from these lesions to represent the first tissue available to study a malignancy from an unknown primary. In general surgical pathology, the evaluation of a metastatic neoplasm of unknown primary is a very complicated process, requiring knowledge of numerous different tumor types, reagents, and staining patterns. The past few years, however, have seen a remarkable refinement in the immunohistochemical tools at our disposal that now empower neuropathologists to take an active role in defining the relatively limited subset of neoplasms that commonly metastasize to the central nervous system. This information can direct imaging studies to find the primary tumor in a patient with an unknown primary, clarify the likely primary site of origin in patients who have small tumors in multiple sites without an obvious primary lesion, or establish lesions as late metastases of remote malignancies. Furthermore, specific treatments can begin and additional invasive procedures may be prevented if the neuropathologic evaluation of metastatic neoplasms provides information beyond the traditional diagnosis of "metastatic neoplasm." In this review, differential cytokeratins, adjuvant markers, and organ-specific antibodies are described and the immunohistochemical signatures of metastatic neoplasms that are commonly seen by neuropathologists are discussed.

Algorithms↗
PubMed2006

Mental status after West Nile virus infection.

Mental status after acute West Nile virus infection has not been examined objectively. We compared Telephone Interview for Cognitive Status scores of 116 patients with West Nile fever or West Nile neuroinvasive disease. Mental status was poorer and cognitive complaints more frequent with West Nile neuroinvasive disease (p = 0.005).

Acute Disease↗
PubMed2005

Young, black, and male in foster care: relationship of negative social contextual experiences to factors relevant to mental health service delivery.

Among a small, cross-sectional sample of young Black males transitioning from foster care (n=74), this study explored the relationship of their negative social contextual experiences to two factors relevant to the delivery of mental health services to them: cultural mistrust of mental health professionals and attitudes toward seeking professional help. Three domains of young Black male's negative social contextual experiences were measured: proximal negative experiences, distal negative experiences, and negative imagery experiences. Results of multivariate analysis of covariance (MANCOVA) controlling for custody status, counselling status and history, and psychiatric history showed that young Black males reporting a high frequency of negative social contextual experiences reported significantly greater cultural mistrust of mental health professionals and significantly less positive attitudes toward seeking professional help for mental health problems than young Black males reporting a low frequency of negative social contextual experiences. Implications and future research directions are discussed.

Adolescent↗
PubMed2005

Central Nervous System Coccidioides immitis Infections.

Coccidioidal meningitis occurs in healthy individuals and patients with AIDS or other immunosuppressive illnesses. The central nervous system infection results when Coccidioides immitis disseminates from a primary lung infection via a fungemia to reach the meninges. Cases develop primarily in individuals living in or traveling to the Lower Sonoran Life Zone of Southwest United States. Most cases begin as subacute granulomatous meningitis with occasional patients developing brain abscesses. Diagnosis may be challenging because C. immitis is isolated from cerebrospinal fluid in less than 50% of patients. However, a cerebrospinal fluid complement fixation test for IgG antibody to C. immitis has high sensitivity and specificity. Currently, optimal treatment is unclear. Standard therapy has been with life-long oral fluconazole or intrathecal amphotericin B followed by prolonged oral fluconazole. Liposomal amphotericin B given intravenously seems promising as an initial treatment as it has much higher brain penetration, less nephrotoxicity, and less severe infusion-related adverse effects than conventional amphotericin B. However, current comparative studies for efficacy of liposomal amphotericin B in coccidioidal meningitis are lacking.

Journal Article↗
PubMed2003

Smallpox and smallpox vaccination: neurological implications.

Compulsory vaccination was discontinued in the U.S. in 1972; the world was declared free of smallpox infection in 1980. Since that time, no new smallpox infections have been recognized, and only limited numbers of military and laboratory personnel have been vaccinated. As a result, the majority of the U.S. and the world population have no or diminished immunity to smallpox. Widespread vaccination, beginning with the military and health care workers, is now being undertaken. Public health strategies for immunizing the general population include preexposure voluntary vaccination, case surveillance with ring vaccination, and mass vaccination at the time of attack. Cutaneous complications of vaccination occur in immunosuppressed subjects and in those with atopic dermatitis. Among the most serious complications is postvaccinal encephalomyelitis (PVEM). A related condition, postvaccinial encephalopathy (PVE), may be seen in children less than two years of age. There are no markers to predict who will develop PVEM. In the past, mortality was high, ranging from 10 to 50%. The neuropathology of PVEM suggested an immune-mediated attack on the CNS, but the target of the immune response is unknown. Comprehensive programs are needed for surveillance and confirming case definitions for neurologic complications. Multi-institutional controlled trials of antiviral and immune modulating therapy of PVEM should be considered. Neurologists should be actively involved in the planning process for vaccination programs and in the treatment of neurologic complications.

Adult↗
PubMed2003

Investigation of the normal proximal somatomotor system using magnetoencephalography.

OBJECTIVE: The role of the ipsilateral cortex in proximal muscle control in normal human subjects is still under debate. One clinical finding, rapid recovery of proximal muscle relative to distal muscle use following stroke, has led to the suggestion that the ipsilateral as well as the contralateral motor cortex may be involved in normal proximal muscle control. The primary goal of this project was to identify contralateral and ipsilateral motor cortex activation associated with proximal muscle movement in normal subjects using magnetoencephalography (MEG). METHODS: We developed protocols for a self-paced bicep motor task and a deltoid, electrical-stimulation somatosensory task. The MEG data were analyzed using automated multi-dipole spatiotemporal modeling techniques to localize the sources and characterize the associated timing of these sources. RESULTS: Reliable contralateral primary motor and somatosensory sources localized to areas consistent with the homunculus. Ipsilateral M1 activation was only found in 2/12 hemispheres. CONCLUSIONS: Robust contralateral motor cortex activation and sparse ipsilateral motor cortex activation suggest that the ipsilateral motor cortex is not involved in normal proximal muscle control. SIGNIFICANCE: The results suggest that proximal and distal muscle control is similar in normal subjects in the sense that proximal muscle control is primarily governed by the contralateral motor cortex.

Adult↗
PubMed2002

Human T lymphocyte response to Borrelia burgdorferi infection: no correlation between human leukocyte function antigen type 1 peptide response and clinical status.

We tested the hypothesis that cross-reactivity between the outer surface protein A (OspA) of Borellia burgdorferi and human leukocyte function antigen (LFA) type 1 mediates chronic autoimmune sequelae of Lyme disease. T cell response was studied in subjects with Lyme disease presenting with erythema migrans alone (n=36), erythema migrans with neurological disease (n=12), and chronic Lyme disease syndrome (n=20), as well as healthy control subjects from Lyme-endemic (n=50) and -nonendemic (n=18) regions. Antigens included recombinant OspA and OspC (all strain B31) and human LFA-1 peptide (IYVIEGTSKQDLTSF). Proliferation to OspA was detected in 11 (28%) of 39 of subjects presenting with erythema migrans, which increased to 50% at 4 weeks of follow-up. Reactivity to OspA and LFA-1 was significantly correlated (P<.001) and was observed in 18 (78%) of 23 of OspA-responsive subjects. However, there was no correlation between T cell response to human LFA-1 peptide and clinical status.

Adolescent↗
PubMed2002

Methanol poisoning exposures in the United States: 1993-1998.

OBJECTIVES: We investigated U.S. methanol-poisoning exposures since little recent information is available about the frequency, sources of methanol, or outcomes of individuals who consume methanol. METHODS: We reviewed human methanol exposures reported to the American Association of Poison Control Centers Toxic Exposure Surveillance System 1993-1998. RESULTS: The mean number of cases per year was 2254. Each year 167 cases had an outcome of moderate effect, major effect, or death. One death occurred in every 183 exposures to methanol. Symptomatic cases increased abruptly from 1.8 to 2.5% for infants and children, from 14.1 to 12.3% for adolescents and adults, while the intentional exposures increased from < 1 to 21% for adolescents, and 11% for adults. Cases occurred in every decade of life but toddlers had the highest number of exposures. In 68 methanol fatalities, confusion developedfollowed by coma, hypotension, respiratory depression, and cerebral edema. Blood methanol levels were above 100mg/dL (70%), metabolic acidoses (62%), and anion gaps > 25 (100%). Methanol products were recorded, showing windshield wiper fluids to be 60.8% of exposures. Other automotive sources were 23.7%. Commercial nonautomotive products were 12.2% and pure methanol products were 2.3%. Unintentional exposures were reported in 90.3% of all cases, while 8.3% were due to intentional exposures, and 1.4% wasfor unknown or mixed reasons. Intentional exposures resulted from suspected suicides (51.2%) and from abuse and misuse (38.8%). CONCLUSIONS: Methanol poisonings continue to occur in the United States with toddlers at the highest risk for exposure, but adolescents and adults at the highest risk for life-threatening intoxications. Over half of product-identified cases were due to consumption of windshield wiperfluid. Efforts should be undertaken to minimize methanol exposures.

Adolescent↗
PubMed2002

Biofilm on ventriculo-peritoneal shunt tubing as a cause of treatment failure in coccidioidal meningitis.

We describe a case of recurrent coccidioidal meningitis in which a fungal biofilm on the tip of ventriculo-peritoneal shunt tubing was likely responsible for a 4-year persistence of Coccidioides immitis, despite the patient's taking an adequate dosage of fluconazole. Fungal biofilms should be considered as a cause for treatment failure and fungal persistence, especially when artificial prostheses or indwelling catheters are present.

Antifungal Agents↗