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L Becker

Publications and source records attributed to L Becker.

At least 55 records · Page 3Linked to original sources
PubMed1999

The origin of organic matter in the Martian meteorite ALH84001.

Stable carbon isotope measurements of the organic matter associated with the carbonate globules and the bulk matrix material in the ALH84001 Martian meteorite indicate that two distinct sources are present in the sample. The delta 13C values for the organic matter associated with the carbonate globules averaged -26% and is attributed to terrestrial contamination. In contrast, the delta 13C values for the organic matter associated with the bulk matrix material yielded a value of -15%. The only common sources of carbon on the Earth that yield similar delta 13C values, other then some diagenetically altered marine carbonates, are C4 plants. A delta 13C value of -15%, on the other hand, is consistent with a kerogen-like component, the most ubiquitous form of organic matter found in carbonaceous chondrites such as the Murchison meteorite. Examination of the carbonate globules and bulk matrix material using laser desorption mass spectrometry (LDMS) indicates the presence of a high molecular weight organic component which appears to be extraterrestrial in origin, possibly derived from the exogenous delivery, of meteoritic or cometary debris to the surface of Mars.

Antarctic Regions↗
PubMed1999

Evidence of widespread axonal pathology in Wolfram syndrome.

Wolfram syndrome, characterised by diabetes insipidus, diabetes mellitus, optic atrophy sensorineural deafness and acquired urinary tract abnormalities, is an hereditary neurodegenerative syndrome, the pathogenesis of which is unknown. We report the post-mortem findings on a patient with well-documented Wolfram syndrome. The brain showed severe degeneration of the optic nerves, chiasm and tracts as well as severe loss of neurons from the lateral geniculate nuclei, basis pontis, and the hypothalamic paraventricular and supraoptic nuclei. In addition, there was a widespread axonal dystrophy with axonal swellings in the pontocerebellar tracts, the optic radiations, the hippocampal fornices and the deep cerebral white matter. This widespread axonal pathology parallels the pattern of neurodegeneration and in many areas is more striking than neuronal loss.

Adult↗
PubMed1999

The origin of organic matter in the Martian meteorite ALH84001.

Stable carbon isotope measurements of the organic matter associated with the carbonate globules and the bulk matrix material in the ALH84001 Martian meteorite indicate that two distinct sources are present in the sample. The delta 13C values for the organic matter associated with the carbonate globules averaged -26% and is attributed to terrestrial contamination. In contrast, the delta 13C values for the organic matter associated with the bulk matrix material yielded a value of -15%. The only common carbon sources on the Earth that yield similar delta 13C values, other then some diagenetically altered marine carbonates, are C4 plants. A delta 13C value of -15%, on the other hand, is consistent with a kerogen-like component, the most ubiquitous form of organic matter found in carbonaceous chondrites such as the Murchison meteorite. Examination of the carbonate globules and bulk matrix material using laser desorption mass spectrometry (LDMS) indicates the presence of a high molecular weight organic component which appears to be extraterrestrial in origin, possibly derived from the exogenous delivery of meteoritic or cometary debris to the surface of Mars.

Amino Acids↗
PubMed1999

Myasthenia gravis and polymyositis as manifestations of chronic graft-versus-host-disease.

Myasthenia gravis and polymyositis are each a rare manifestation of immune dysregulation in chronic graft-versus-host disease (cGVHD). We report a 4-year-old boy with idiopathic acquired aplastic anemia who developed myasthenia gravis 22 months and polymyositis 69 months after an allogeneic BMT (5/6 matched, MLC-nonreactive). The occurrence of both syndromes in one patient is unique. Autoimmune dysfunction may be associated with the development of cGVHD as demonstrated by the high incidence of prior aplastic anemia in BMT patients presenting with myasthenia gravis and polymyositis. Recognition of these neurologic manifestations is important in the diagnosis and treatment of cGVHD.

Anemia, Aplastic↗
PubMed1999

Measles inclusion-body encephalitis caused by the vaccine strain of measles virus.

We report a case of measles inclusion-body encephalitis (MIBE) occurring in an apparently healthy 21-month-old boy 8.5 months after measles-mumps-rubella vaccination. He had no prior evidence of immune deficiency and no history of measles exposure or clinical disease. During hospitalization, a primary immunodeficiency characterized by a profoundly depressed CD8 cell count and dysgammaglobulinemia was demonstrated. A brain biopsy revealed histopathologic features consistent with MIBE, and measles antigens were detected by immunohistochemical staining. Electron microscopy revealed inclusions characteristic of paramyxovirus nucleocapsids within neurons, oligodendroglia, and astrocytes. The presence of measles virus in the brain tissue was confirmed by reverse transcription polymerase chain reaction. The nucleotide sequence in the nucleoprotein and fusion gene regions was identical to that of the Moraten and Schwarz vaccine strains; the fusion gene differed from known genotype A wild-type viruses.

Encephalitis, Viral↗
PubMed1999

Central neurocytoma: morphological, flow cytometric, polymerase chain reaction, fluorescence in situ hybridization, and karyotypic analyses. Case report.

The results of cytogenetic and molecular genetic analysis of a central neurocytoma are presented. Central neurocytomas are intriguing neoplasms that exhibit primarily neuronal, but also glial characteristics, which indicate an origin from a pluripotential neuroglial precursor. The authors describe an intraventricular neurocytoma in an 11-year-old boy that showed anaplastic features with widespread necrosis and mitoses, as well as extensive calcification and foci that exhibited marked neuronal differentiation with clusters of ganglion cells. Immunohistochemical examination showed prominent synaptophysin and neurofilament positivity and focal glial fibrillary acidic protein positivity. Electron microscopy revealed abundant neuritic processes with microtubules and dense core granules as well as mature ganglion cells. Flow cytometry studies revealed increased S (7.8%) and G2M (9.7%) phase components. Molecular and cytogenetic studies were undertaken to assess whether there were similarities to two other tumor types that exhibit neuronal differentiation, the neuroblastoma and medulloblastoma. Polymerase chain reaction and fluorescence in situ hybridization (FISH) analysis revealed no evidence of amplification of the MYCN oncogene or chromosome 1p deletion, which are common in neuroblastomas. Chromosomal analysis by G banding revealed a complex karyotype, with counts in the near-diploidy range (45-48). Two chromosomes 1 appeared normal on G banding and FISH analysis, with p58 signals present on the distal p arm of both chromosomes 1; however, three additional copies of distal 1q were present in rearrangements with 4 and 7. Although the histological findings indicate a kinship to the neuroblastoma and medulloblastoma, the central neurocytoma appears to have a different karyotypic profile, although more cases need to be assessed using molecular genetic analysis.

Brain Neoplasms↗
PubMed1998

Public locations of cardiac arrest. Implications for public access defibrillation.

BACKGROUND: The purpose of this study was to describe the public locations of cardiac arrest and to estimate the annual incidence of cardiac arrest per site to determine optimal placement of automatic external defibrillators (AEDs). This was a retrospective cohort study. METHODS AND RESULTS: Locations of cardiac arrest were abstracted from data collected by emergency medical service programs in Seattle and King County, Washington, from January 1, 1990, through December 31, 1994. Types of commercial and civic establishments were tallied and grouped into 23 location categories consistent with Standard Industrial Codes, and the number of sites within each location category was determined. With the addition of "public outdoors" and "automobiles" as categories, there were 25 location categories. During the study period, 7185 arrests occurred, 1130 (16%) of which were in public locations. An annual incidence of cardiac arrest per site was calculated. Ten location categories with 172 sites were identified as having a higher incidence of cardiac arrest (> or = .03 per year per site). Thirteen location categories had a lower incidence of arrest (< or = .01 per year per site). There were approximately 71,000 sites within these categories. CONCLUSIONS: Placement of 276 AEDs in the 172 higher-incidence sites would have provided treatment for 134 cardiac arrest patients in a 5-year period, 60% of whom were in ventricular fibrillation. We estimate between 8 and 32 lives could be saved in 5 years. To cover the remaining 347 arrests occurring in public in a 5-year period, defibrillators would have to be placed in 71,000 sites, not including outdoors and automobiles. Placement of AEDs in public locations can be guided by the site-specific incidence of arrest.

Electric Countershock↗
PubMed1998

Cardiac failure in transgenic mice with myocardial expression of tumor necrosis factor-alpha.

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha) is a multifunctional cytokine that has been detected in several human cardiac-related conditions, including congestive heart failure and septic cardiomyopathy. In these conditions, the origin of TNF-alpha secretion is, at least in part, cardiac myocytes. METHODS AND RESULTS: To determine the consequences of TNF-alpha production by cardiac myocytes in vivo, we developed transgenic mice in which expression of a murine TNF-alpha coding sequence was driven by the murine alpha-myosin heavy chain promoter. Four transgenic founders developed an identical illness consisting of tachypnea, decreased activity, and hunched posture. In vivo, ECG-gated MRI of symptomatic transgenic mice documented a severe impairment of cardiac function evidenced by biventricular dilatation and depressed ejection fractions. All transgenic mice died prematurely. Pathological examination of affected animals revealed a globular dilated heart, bilateral pleural effusions, myocyte apoptosis, and transmural myocarditis in both the right and left ventricular free walls, septum, and atrial chambers. In all terminally ill animals, there was significant biventricular fibrosis and atrial thrombosis. CONCLUSIONS: This is the first report detailing the effects of tissue-specific production of TNF-alpha by cardiac myocytes in vivo. These findings indicate that production of TNF-alpha by cardiac myocytes is sufficient to cause severe cardiac disease and support a causal role for this cytokine in the pathogenesis of human cardiac disease.

Animals↗
PubMed1998

A search for endogenous amino acids in martian meteorite ALH84001.

Trace amounts of glycine, serine, and alanine were detected in the carbonate component of the martian meteorite ALH84001 by high-performance liquid chromatography. The detected amino acids were not uniformly distributed in the carbonate component and ranged in concentration from 0.1 to 7 parts per million. Although the detected alanine consists primarily of the L enantiomer, low concentrations (<0.1 parts per million) of endogenous D-alanine may be present in the ALH84001 carbonates. The amino acids present in this sample of ALH84001 appear to be terrestrial in origin and similar to those in Allan Hills ice, although the possibility cannot be ruled out that minute amounts of some amino acids such as D-alanine are preserved in the meteorite.

Alanine↗
PubMed1998

Axonal injury and the neuropathology of shaken baby syndrome.

We examined an autopsy series of 14 children with shaken baby syndrome (SBS) who lacked skull fracture. Evidence of axonal injury was sought using immunohistochemical stains for neurofilament, 68-kDa neurofilament and beta-amyloid precursor protein (betaAPP). BetaAPP-positive axons were present in the cerebral white matter of all cases of SBS but were also present in 6 of 7 children dying of non-traumatic hypoxic ischemic encephalopathy (HIE). Swollen axons were present in 11 of 14 cases of SBS and in 6 of 7 cases of HIE. BetaAPP-positive axons were present in both groups in the midbrain and medulla. The cervical spinal cord in SBS contained betaAPP-positive axons in 7 of 11 cases; 5 of 7 contained swollen axons within the white matter tracts; in 2 immunoreactivity was localized to spinal nerve roots; in all 7 there was a predilection for staining at the glial head of the nerve root. Among cases of HIE, none showed abnormal axons or betaAPP-positive reactivity in the cervical cord white matter. We conclude that cerebral axonal injury is common in SBS, and may be due in part to hypoxic/ischemic injury. Cervical cord injury is also common, and cannot be attributed to HIE. These findings corroborate suggestions that flexion-extension injury about the cervical spinal column may be important in the pathogenesis of SBS.

Amyloid beta-Protein Precursor↗
PubMed1998

Relationships of race and socioeconomic status with prevalence, severity, and symptoms of asthma in Chicago school children.

BACKGROUND: Asthma mortality rates in Chicago are among the highest in the United States, with substantially greater rates in poor and minority populations. How much of the differential can be attributed to differences in prevalence versus severity or access to care has not been determined. OBJECTIVE: To examine rates of asthma prevalence, severity, and symptoms and to explore the relationships of these rates to race and socioeconomic status in a random sample of Chicago school children. METHODS: Self-administered survey. RESULTS: Overall, rates of asthma were higher than previously reported, with 16% of students in the stratified cluster random sample of 3,670 children in the 7th and 8th grades having had asthma. Prevalence rates were significantly higher in schools with >98% African Americans than in other schools, with the highest prevalence rates seen in African American schools in low income neighborhoods. Rates were associated with the percent of African American children in the school and with median income of the school's census tract. Relationships were most consistent with indices of more severe disease. CONCLUSIONS: Asthma prevalence is higher than previously noted, with rates greatest in minority and low income populations. Differences are more striking for measures of severity than for symptoms of wheezing, but are far less than previously reported differences in mortality, suggesting that additional factors, such as differential access to continuous health care, may be affecting high death rates from asthma in Chicago.

Adolescent↗
PubMed1998

Chondrosarcoma of the maxilla: panoramic radiographic and computed tomographic with multiplanar reconstruction findings.

Chondrosarcomas are extremely rare tumors of which approximately 10% are found in the maxillofacial region. In this report, we present the imaging findings of a maxillary chondrosarcoma on a panoramic radiograph of the jaws and computed tomography with multiplanar reconstructions. We recommend the latter as an excellent way to image evolving or suspected lesions of the maxilla, particularly for surgical treatment planning.

Adult↗