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Biomedical subjects

L Richter

Publications and source records attributed to L Richter.

At least 19 recordsLinked to original sources
PubMed2006

[Infections with herpes simplex and varicella-zoster viruses during pregnancy].

Primary infections with herpes simplex virus (HSV) and varicella-zoster virus (VZV) may lead to severe illness in pregnancy. Both diseases may be associated with transplacental virus transmission and fetal infection. Such infections can lead to intrauterine death, severe malformations and premature birth; the fetal/congenital varicella syndrome is well-defined. Herpes genitalis and varicella at the time of labor may lead to life threatening neonatal-herpes or varicella of the newborn. Currently neither active immunization nor neutralizing immunoglobulin is available for HSV infections. VZV-seronegative women in child-bearing age can be vaccinated and pregnant women exposed to VZV can be given specific immunoglobulins. While an infection is rarely blocked, the severity is generally reduced. For severe disease antiviral treatment is necessary, with valacyclovir and acyclovir represents the drugs of choice. Primary or recurrent overt disease of the genital tract at the time of delivery an indication for caesarean section. Suppression of recurrent genital herpes during the last weeks of pregnancy with valacyclovir and acyclovir reduces the need for surgical intervention. Neonates exposed to VZV should receive specific immunoglobulin. If neonates show signs of either infection, immediate treatment with acyclovir must be initiated.

Cesarean Section↗
PubMed2004

Localization and physical property experiments conducted by Opportunity at Meridiani Planum.

The location of the Opportunity landing site was determined to better than 10-m absolute accuracy from analyses of radio tracking data. We determined Rover locations during traverses with an error as small as several centimeters using engineering telemetry and overlapping images. Topographic profiles generated from rover data show that the plains are very smooth from meter- to centimeter-length scales, consistent with analyses of orbital observations. Solar cell output decreased because of the deposition of airborne dust on the panels. The lack of dust-covered surfaces on Meridiani Planum indicates that high velocity winds must remove this material on a continuing basis. The low mechanical strength of the evaporitic rocks as determined from grinding experiments, and the abundance of coarse-grained surface particles argue for differential erosion of Meridiani Planum.

Extraterrestrial Environment↗
PubMed2004

Soils of Eagle crater and Meridiani Planum at the Opportunity Rover landing site.

The soils at the Opportunity site are fine-grained basaltic sands mixed with dust and sulfate-rich outcrop debris. Hematite is concentrated in spherules eroded from the strata. Ongoing saltation exhumes the spherules and their fragments, concentrating them at the surface. Spherules emerge from soils coated, perhaps from subsurface cementation, by salts. Two types of vesicular clasts may represent basaltic sand sources. Eolian ripples, armored by well-sorted hematite-rich grains, pervade Meridiani Planum. The thickness of the soil on the plain is estimated to be about a meter. The flatness and thin cover suggest that the plain may represent the original sedimentary surface.

Extraterrestrial Environment↗
PubMed2004

Evidence from Opportunity's Microscopic Imager for water on Meridiani Planum.

The Microscopic Imager on the Opportunity rover analyzed textures of soils and rocks at Meridiani Planum at a scale of 31 micrometers per pixel. The uppermost millimeter of some soils is weakly cemented, whereas other soils show little evidence of cohesion. Rock outcrops are laminated on a millimeter scale; image mosaics of cross-stratification suggest that some sediments were deposited by flowing water. Vugs in some outcrop faces are probably molds formed by dissolution of relatively soluble minerals during diagenesis. Microscopic images support the hypothesis that hematite-rich spherules observed in outcrops and soils also formed diagenetically as concretions.

Extraterrestrial Environment↗
PubMed2004

The Opportunity Rover's Athena science investigation at Meridiani Planum, Mars.

The Mars Exploration Rover Opportunity has investigated the landing site in Eagle crater and the nearby plains within Meridiani Planum. The soils consist of fine-grained basaltic sand and a surface lag of hematite-rich spherules, spherule fragments, and other granules. Wind ripples are common. Underlying the thin soil layer, and exposed within small impact craters and troughs, are flat-lying sedimentary rocks. These rocks are finely laminated, are rich in sulfur, and contain abundant sulfate salts. Small-scale cross-lamination in some locations provides evidence for deposition in flowing liquid water. We interpret the rocks to be a mixture of chemical and siliciclastic sediments formed by episodic inundation by shallow surface water, followed by evaporation, exposure, and desiccation. Hematite-rich spherules are embedded in the rock and eroding from them. We interpret these spherules to be concretions formed by postdepositional diagenesis, again involving liquid water.

Atmosphere↗
PubMed2004

Surficial deposits at Gusev Crater along Spirit Rover traverses.

The Mars Exploration Rover Spirit has traversed a fairly flat, rock-strewn terrain whose surface is shaped primarily by impact events, although some of the landscape has been altered by eolian processes. Impacts ejected basaltic rocks that probably were part of locally formed lava flows from at least 10 meters depth. Some rocks have been textured and/or partially buried by windblown sediments less than 2 millimeters in diameter that concentrate within shallow, partially filled, circular impact depressions referred to as hollows. The terrain traversed during the 90-sol (martian solar day) nominal mission shows no evidence for an ancient lake in Gusev crater.

Extraterrestrial Environment↗
PubMed2004

Localization and physical properties experiments conducted by Spirit at Gusev Crater.

The precise location and relative elevation of Spirit during its traverses from the Columbia Memorial station to Bonneville crater were determined with bundle-adjusted retrievals from rover wheel turns, suspension and tilt angles, and overlapping images. Physical properties experiments show a decrease of 0.2% per Mars solar day in solar cell output resulting from deposition of airborne dust, cohesive soil-like deposits in plains and hollows, bright and dark rock coatings, and relatively weak volcanic rocks of basaltic composition. Volcanic, impact, aeolian, and water-related processes produced the encountered landforms and materials.

Extraterrestrial Environment↗
PubMed2004

Wind-related processes detected by the Spirit Rover at Gusev Crater, Mars.

Wind-abraded rocks, ripples, drifts, and other deposits of windblown sediments are seen at the Columbia Memorial Station where the Spirit rover landed. Orientations of these features suggest formative winds from the north-northwest, consistent with predictions from atmospheric models of afternoon winds in Gusev Crater. Cuttings from the rover Rock Abrasion Tool are asymmetrically distributed toward the south-southeast, suggesting active winds from the north-northwest at the time (midday) of the abrasion operations. Characteristics of some rocks, such as a two-toned appearance, suggest that they were possibly buried and exhumed on the order of 5 to 60 centimeters by wind deflation, depending on location.

Evolution, Planetary↗
PubMed2004

The Spirit Rover's Athena science investigation at Gusev Crater, Mars.

The Mars Exploration Rover Spirit and its Athena science payload have been used to investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a former lake, but no clear evidence for lacustrine sedimentation has been found to date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. Many rocks exhibit coatings and other characteristics that may be evidence for minor aqueous alteration. Any lacustrine sediments that may exist at this location within Gusev apparently have been buried by lavas that have undergone subsequent impact disruption.

Atmosphere↗
PubMed2004

The effects of repeated intra-amygdala CRF injections on rat behavior and HPA axis function after stress.

Patients diagnosed with certain anxiety disorders or depression show symptoms of a dysregulated HPA-axis secondary to increased release of corticotropin releasing factor (CRF). Male Wistar rats were injected with CRF (100 ng/microL) in the basolateral amygdala (BLA) for 5 days. Measurement of behavior was performed on the elevated plus maze and open field test. Behavioral and neuroendocrine response to restraint stress was also evaluated. Chronic treatment of CRF resulted in a significant increase in grooming after restraint stress in the Open Field test. Basal plasma corticosterone concentrations were significantly lower in the CRF-injected rats. These animals also showed greater and longer increase in corticosterone levels following the restraint stress than controls, but had comparable ACTH responses to restraint stress. Our results indicate that chronic administration of CRF into the basolateral amygdala may promote stress-induced grooming behavior in rats. In addition the data suggests that increased CRF in the amygdala may contribute to the dysregulation of corticosterone secretion. These findings may have important implications for patients suffering from psychiatric illnesses such as posttraumatic stress disorder and depression that are characterized by abnormalities in cortisol release.

Adrenocorticotropic Hormone↗
PubMed2002

Coping with the stress of a painful medical procedure.

To evaluate its effect on procedure-related distress, the focus of attention was manipulated by providing training to hospitalized acute burn patients (n=42). Participants were randomly assigned to attention focusing (i.e. attending to procedural sensations) or music distraction (i.e. attention diverting) coping interventions, or to usual care during the target dressing change. Coping behavior (i.e. distraction, focusing, and three confounding methods, ignoring, catastrophizing, reinterpreting), tension and intrusiveness were evaluated 24 h retrospectively (i.e. for the prior procedure), during the targeted procedure, and 30 min after the target procedure. When coping during the target procedure by ignoring, reinterpreting, and catastrophizing were covaried, the music distraction group experienced significantly fewer intrusions, and the attention focus group had more intrusions. Additionally, secondary analyses revealed that coping by ignoring during the prior day's procedure significantly predicted higher procedural tension during, and more intrusions following, the targeted procedure. Suppression-based forms of emotion-focused coping may be enhanced by training in the use of an explicit distractor.

Acute Disease↗
PubMed2001

Oral immunization with hepatitis B surface antigen expressed in transgenic plants.

Oral immunogenicity of recombinant hepatitis B surface antigen (HBsAg) derived from yeast (purified product) or in transgenic potatoes (uncooked unprocessed sample) was compared. An oral adjuvant, cholera toxin, was used to increase immune responses. Transgenic plant material containing HBsAg was the superior means of both inducing a primary immune response and priming the mice to respond to a subsequent parenteral injection of HBsAg. Electron microscopy of transgenic plant samples revealed evidence that the HBsAg accumulated intracellularly; we conclude that natural bioencapsulation of the antigen may provide protection from degradation in the digestive tract until plant cell degradation occurs near an immune effector site in the gut. The correlate of protection from hepatitis B virus infection is serum antibody titers induced by vaccination; the protective level in humans is 10 milliunits/ml or greater. Mice fed HBsAg-transgenic potatoes produced HBsAg-specific serum antibodies that exceeded the protective level and, on parenteral boosting, generated a strong long-lasting secondary antibody response. We have also shown the effectiveness of oral delivery by using a parenteral prime-oral boost immunization schedule. The demonstrated success of oral immunization for hepatitis B virus with an "edible vaccine" provides a strategy for contributing a means to achieve global immunization for hepatitis B prevention and eradication.

Animals↗
PubMed2001

Vascular endothelial cell growth factor is an autocrine promoter of abnormal localized immature myeloid precursors and leukemia progenitor formation in myelodysplastic syndromes.

Vascular endothelial growth factor (VEGF) is a potent angiogenic peptide with biologic effects that include regulation of hematopoietic stem cell development, extracellular matrix remodeling, and inflammatory cytokine generation. To delineate the potential role of VEGF in patients with myelodysplastic syndrome (MDS), VEGF protein and receptor expression and its functional significance in MDS bone marrow (BM) were evaluated. In BM clot sections from normal donors, low-intensity cytoplasmic VEGF expression was detected infrequently in isolated myeloid elements. However, monocytoid precursors in chronic myelomonocytic leukemia (CMML) expressed VEGF in an intense cytoplasmic pattern with membranous co-expression of the Flt-1 or KDR receptors, or both. In situ hybridization confirmed the presence of VEGF mRNA in the neoplastic monocytes. In acute myelogenous leukemia (AML) and other MDS subtypes, intense co-expression of VEGF and one or both receptors was detected in myeloblasts and immature myeloid elements, whereas erythroid precursors and lymphoid cells lacked VEGF and receptor expression. Foci of abnormal localized immature myeloid precursors (ALIP) co-expressed VEGF and Flt-1 receptor, suggesting autocrine cytokine interaction. Antibody neutralization of VEGF inhibited colony-forming unit (CFU)-leukemia formation in 9 of 15 CMML and RAEB-t patient specimens, whereas VEGF stimulated leukemia colony formation in 12 patients. Neutralization of VEGF activity suppressed the generation of tumor necrosis factor-alpha and interleukin-1beta from MDS BM-mononuclear cells and BM-stroma and promoted the formation of CFU-GEMM and burst-forming unit-erythroid in methylcellulose cultures. These findings indicate that autocrine production of VEGF may contribute to leukemia progenitor self-renewal and inflammatory cytokine elaboration in CMML and MDS and thus provide a biologic rationale for ALIP and its adverse prognostic relevance in high-risk MDS.

Antibodies, Monoclonal↗
PubMed2001

Exposure to violence, coping resources, and psychological adjustment of South African children.

The effects of exposure to direct and vicarious political, family, and community violence on the adjustment of 625 six-year-old black South African children was examined. Ambient community violence was most consistently related to children's psychosocial outcomes. Resources in the form of individual child resilience, maternal coping, and positive family relationships were found to mitigate the adverse impact in all the assessed domains of children's functioning.

Adaptation, Psychological↗
PubMed2001

Exposure to parental tobacco and alcohol use: effects on children's health and development.

This review examines three ways in which parental tobacco and alcohol use compromises the physical and mental health of children: 1) direct exposure to the substances; 2) living with parents who may become ill from using these substances; and 3) children's modeling of parental substance use. Implications for prevention, intervention, and public education are discussed, and a reframing of the national dialogue on youth substance abuse is called for.

Adult↗
PubMed2001

Telepathology overview: from concept to implementation.

Telepathology is the practice of pathology at a distance by using video imaging and telecommunications. Significant progress has been made in telepathology. To date, 12 classes of telepathology systems have been engineered. Rapid and ultrarapid virtual slide processors may further expand the range of telepathology applications. Next-generation digital imaging light microscopes, such as miniaturized microscope arrays (MMA), may make virtual slide processing a routine laboratory tool. Diagnostic accuracy of telepathology is comparable with that of conventional light microscopy for most diagnoses. Current telepathology applications include intraoperative frozen sections services, routine surgical pathology services, second opinions, and subspecialty consultations. Three telepathology practice models are discussed: the subspecialty practice (SSP) model; the case triage practice (CTP) model; and the virtual group practice (VGP) model. Human factors influence performance with telepathology. Experience with 500 telepathology cases from multiple organs significantly reduces the video viewing time per case (P < .01). Many technology innovations can be represented as S-curves. After long incubation periods, technology use and/or efficiency may accelerate. Telepathology appears to be following an S-curve for a technical innovation.

Diffusion of Innovation↗
PubMed2001

Risk factors for adolescent marijuana use across cultures and across time.

An integrated analysis of the data from 3 different studies was conducted to examine the early psychosocial predictors of later marijuana use among adolescents. Longitudinal analysis of interview data was performed. The data used in the analysis were derived from (a) a sample of 739 predominantly White adolescents representative of the northeastern United States, (b) a sample of 1,190 minority adolescents from the East Harlem section of New York City, and (c) a sample of 1,374 Colombian adolescents from two cities in Colombia, South America. In 2 of the samples, participants were interviewed in their homes, and in the 3rd study, participants were assessed in school. The predictors included a number of variables from (a) the personality domain, reflecting the adolescents' conventionality and intrapsychic functioning; (b) the family domain, representing the parent-child mutual attachment relationship and parental substance use; (c) the peer domain, reflecting the peer group's delinquency and substance use; and (d) the adolescents' own use of legal drugs. The dependent variable was adolescent marijuana use. The results of the analysis demonstrated remarkable consistency in the risk and protective factors for later marijuana use across the 3 samples, attesting to the robust nature of these predictors and their generalizability across gender, time, location, and ethnic/cultural background. These findings have important implications for designing intervention programs. Programs aimed at preventing adolescent marijuana use can be designed to incorporate universal features and still incorporate specific components that address the unique needs of adolescents from different groups.

Adolescent↗