NASA's Satellite Laser Ranging Systems for the 21st Century.

For over 40 years, NASA's global network of satellite laser ranging (SLR) stations has provided a significant percentage of the global orbital data used to define the International Terrestrial Reference Frame (ITRF). The current NASA legacy network is reaching its end-of-life and a new generation of systems must be ready to take its place. Scientific demands of sub-millimeter precision ranging and the ever-increasing number of tracking targets give aggressive performance requirements to this new generation of systems. Using lessons learned from the legacy systems and the successful development of a prototype station, a new network of SLR stations, called the Space Geodesy Satellite Laser Ranging (SGSLR) systems, is being developed. These will be the state-of-the-art SLR component of NASA's Space Geodesy Project (SGP). Each of SGSLR's nine subsystems has been designed to produce a robust, kilohertz laser ranging system with 24/7 operational capability and with minimal human intervention. SGSLR's data must support the aggressive goals of the Global Geodetic Observing System (GGOS), which are 1 millimeter (mm) position accuracy and 0.1 mm per year stability of the ITRF. This paper will describe the major requirements and accompanying design of the new SGSLR systems, how the systems will be tested, and the expected system performance.

Estimating the prevalence of active Helicobacter pylori infection in a rural community with global positioning system technology-assisted sampling.

We investigated a possible outbreak of H. pylori in a rural Northern Plains community. In a cross-sectional survey, we randomly sampled 244 households from a geocoded emergency medical system database. We used a complex survey design and global positioning system units to locate houses and randomly selected one eligible household member to administer a questionnaire and a 13C-urea breath test for active H. pylori infection (n = 166). In weighted analyses, active H. pylori infection was detected in 55·0% of the sample. Factors associated with infection on multivariate analysis included using a public drinking-water supply [odds ratio (OR) 12·2, 95% confidence interval (CI) 2·9-50·7] and current cigarette smoking (OR 4·1, 95% CI 1·7-9·6). People who lived in houses with more rooms, a possible indicator of decreased crowding in the home, were less likely to have active H. pylori infections (OR 0·7, 95% CI 0·5-0·9 for each additional room).

Added value of a household-level study during an outbreak investigation of Salmonella serotype Saintpaul infections, New Mexico 2008.

In 2008, nationwide investigations of a Salmonella serotype Saintpaul outbreak led first to consumer warnings for Roma and red round tomatoes, then later for jalapeño and serrano peppers. In New Mexico, where there were a large number of cases but no restaurant-based clusters, the NM Department of Health and the Indian Health Service participated with CDC in individual-level and household-level case-control studies of infections in New Mexico and the Navajo Nation. No food item was associated in the individual-level study. In the household-level study, households with an ill member were more likely to have had jalapeño peppers present during the exposure period and to have reported ever having serrano peppers in the household. This report illustrates the complexity of this investigation, the limitations of traditional individual-level case-control studies when vehicles of infection are ingredients or commonly eaten with other foods, and the added value of a household-level study.

An outbreak of Rocky Mountain Spotted Fever associated with a novel tick vector, Rhipicephalus sanguineus, in Arizona, 2004: preliminary report.

This study describes preliminary results of an investigation of RMSF in Arizona associated with the brown dog tick, Rhipicephalus sanguineus. High numbers of dogs and heavy infestations of ticks created a situation leading to human disease.

Adjuncts to mechanical ventilation in ARDS.

Since its first description, acute respiratory distress syndrome has been characterized by abnormal physiologic and gas exchange properties of the lungs. Many adjunctive therapies have been developed to reduce the stresses of mechanical ventilation on already damaged lungs. We examined the mechanism of action and the latest clinical trial information of several adjunctive therapies including prone positioning, nitric oxide, extracorporeal membrane oxygenation, arterial venous carbon dioxide removal, and liquid ventilation. While all of these therapies have demonstrated short-term improvements in arterial blood gases and in the limitation of lung injury, none have shown an evidence-based survival benefit.

Creutzfeldt-Jakob disease among American Indians and Alaska Natives in the United States.

The occurrence of Creutzfeldt-Jakob disease (CJD) among American Indians and Alaska Natives in the United States was evaluated using national multiple cause-of-death data and medical information obtained from state health departments. Twelve CJD deaths were identified for 1981 through 2002, and the average annual age-adjusted death rate was 0.47 per million population. This rate was significantly lower than that for whites and similar to the rate for African Americans.

Community-acquired methicillin-resistant Staphylococcus aureus in a rural American Indian community.

CONTEXT: Until recently, methicillin-resistant Staphylococcus aureus (MRSA) infections have been acquired primarily in nosocomial settings. Four recent deaths due to MRSA infection in previously healthy children in the Midwest suggest that serious MRSA infections can be acquired in the community in rural as well as urban locations. OBJECTIVES: To document the occurrence of community-acquired MRSA infections and evaluate risk factors for community-acquired MRSA infection compared with methicillin-susceptible S aureus (MSSA) infection. DESIGN: Retrospective cohort study with medical record review. SETTING: Indian Health Service facility in a rural midwestern American Indian community. PATIENTS: Patients whose medical records indicated laboratory-confirmed S aureus infection diagnosed during 1997. MAIN OUTCOME MEASURES: Proportion of MRSA infections classified as community acquired based on standardized criteria; risk factors for community-acquired MRSA infection compared with those for community-acquired MSSA infection; and relatedness of MRSA strains, determined by pulsed-field gel electrophoresis (PFGE). RESULTS: Of 112 S aureus isolates, 62 (55%) were MRSA and 50 (45%) were MSSA. Forty-six (74%) of the 62 MRSA infections were classified as community acquired. Risk factors for community-acquired MRSA infections were not significantly different from those for community-acquired MSSA. Pulsed-field gel electrophoresis subtyping indicated that 34 (89%) of 38 community-acquired MRSA isolates were clonally related and distinct from nosocomial MRSA isolates found in the region. CONCLUSIONS: Community-acquired MRSA may have replaced community-acquired MSSA as the dominant strain in this community. Antimicrobial susceptibility patterns and PFGE subtyping support the finding that MRSA is circulating beyond nosocomial settings in this and possibly other rural US communities.

Epidemiology and clonality of community-acquired methicillin-resistant Staphylococcus aureus in Minnesota, 1996-1998.

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged among patients in the general population who do not have established risk factors for MRSA. Records from 10 Minnesota health facilities were reviewed to identify cases of MRSA infection that occurred during 1996-1998 and to identify which cases were community acquired. Susceptibility testing and pulsed-field gel electrophoresis (PFGE) subtyping were performed on available isolates. A total of 354 patients (median age, 16 years) with community-acquired MRSA (CAMRSA) infection were identified. Most case patients (299 [84%]) had skin infections, and 103 (29%) were hospitalized. More than 90% of isolates were susceptible to all antimicrobial agents tested, with the exception of beta-lactams and erythromycin. Of 334 patients treated with antimicrobial agents, 282 (84%) initially were treated with agents to which their isolates were nonsusceptible. Of 174 Minnesota isolates tested, 150 (86%) belonged to 1 PFGE clonal group. CAMRSA infections were identified throughout Minnesota; although most isolates were genetically related and susceptible to multiple antimicrobials, they were generally nonsusceptible to initial empirical therapy.

Adenosylmethionine-dependent iron-sulfur enzymes: versatile clusters in a radical new role.

Iron-sulfur clusters are widespread in biological systems and participate in a broad range of functions. These functions include electron transport, mediation of redox as well as non-redox catalysis, and regulation of gene expression. A new role for iron-sulfur clusters has emerged in recent years as a number of enzymes have been identified that utilize Fe-S clusters and S-adenosylmethionine (AdoMet) to initiate radical catalysis. This Fe-S cluster-mediated radical catalysis includes the generation of stable protein-centered radicals as well as generation of substrate radical intermediates, with evidence suggesting a common mechanism involving an intermediate adenosyl radical. Although the mechanism of generation of the adenosyl radical intermediate is currently not well understood, it likely represents novel chemistry for iron-sulfur clusters. The purpose of this review is to present the current state of knowledge of this newly emerging group of Fe-S/AdoMet enzymes.

Trends in infectious disease hospitalizations among American Indians and Alaska Natives.

OBJECTIVES: This study sought to describe trends in hospitalizations associated with infectious diseases among American Indians and Alaska Natives. METHODS: Infectious disease hospitalizations and rates among American Indians and Alaska Natives from 1980 through 1994 were examined via Indian Health Service hospital discharge data and compared with published trends for the general US population. RESULTS: Annual hospitalization rates for infectious diseases among American Indians and Alaska Natives decreased by 31.0% between 1980 and 1994. Infectious disease hospitalizations accounted for 16.3% of all hospitalizations in 1980 and 21.2% in 1994, an increase of 30.1%. In 1994, the age-adjusted infectious disease hospitalization rate for American Indians and Alaska Natives was 1863 per 100,000 population, approximately 21% greater than that for the general US population. CONCLUSIONS: Hospitalization trends for infectious diseases show that there has been improvement in the health status of American Indians and Alaska Natives but also indicate that this population has a higher infectious disease burden than the general US population.

Moving them on and in: the process of searching for and selecting an aged care facility.

This exploratory, descriptive study examined the search and selection process for an aged care facility following discharge of a family member from an acute setting. Few studies have examined this process and its effects on families. Individuals from 25 families where a family member had been recently admitted to an aged care facility following discharge from an acute setting were interviewed. This article reports participants' perceptions of the search and selection process and its effect on the family. Five major themes emerged from the data: good fortune, wear and tear on the sponsor, dealing with the system, urgency, and adjusting. The results can be used to inform and assist families and health professionals working with families in this situation.

Coping with crisis: how Australian families search for and select an aged care facility for a family member upon discharge from an acute care setting.

Searching for, and selecting, an aged care facility for a family member upon his or her discharge from an acute setting is known, anecdotally, to be a challenge; but the process itself, and its effects on families, has seldom been examined. In this exploratory/descriptive study, face-to-face in-depth interviews were conducted with sponsors (often family members) of residents who had been admitted to an aged care facility within the past 90 days, following their discharge from an acute care setting. Where possible, both sponsor and resident were interviewed. This paper reports on the participants' perceptions of the search and selection process. Specific areas of interest were probed: Why and how the decision was made to seek residential placement; when and how the search for an aged care facility began; factors that were important in the family's final selection process; what happened when families, either initially or in the long term, were unable to find a place in an aged care facility; and the family's perspective about the efficacy of the search and selection process and its effect on the well being of the family. Residents are often passive in the search and selection process, while sponsors are often actively involved. Very few residents or sponsors consider planning for an aged care facility prior to hospitalisation, and there is often the perception by families of having very little support at this stressful and emotional time. The decision to relocate a family member in these circumstances is a stressful experience and should be viewed as a family crisis, particularly if unexpected such as upon discharge from an acute setting. These findings provide valuable insights that can be used to guide and assist families experiencing this process, as well as health care professionals working with families in this situation.

Escherichia coli LipA is a lipoyl synthase: in vitro biosynthesis of lipoylated pyruvate dehydrogenase complex from octanoyl-acyl carrier protein.

The Escherichia coli lipA gene product has been genetically linked to carbon-sulfur bond formation in lipoic acid biosynthesis [Vanden Boom, T. J., Reed, K. E., and Cronan, J. E., Jr. (1991) J. Bacteriol. 173, 6411-6420], although in vitro lipoate biosynthesis with LipA has never been observed. In this study, the lipA gene and a hexahistidine tagged lipA construct (LipA-His) were overexpressed in E. coli as soluble proteins. The proteins were purified as a mixture of monomeric and dimeric species that contain approximately four iron atoms per LipA polypeptide and a similar amount of acid-labile sulfide. Electron paramagnetic resonance and electronic absorbance spectroscopy indicate that the proteins contain a mixture of [3Fe-4S] and [4Fe-4S] cluster states. Reduction with sodium dithionite results in small quantities of an S = 1/2 [4Fe-4S](1+) cluster with the majority of the protein containing a species consistent with an S = 0 [4Fe-4S](2+) cluster. LipA was assayed for lipoate or lipoyl-ACP formation using E. coli lipoate-protein ligase A (LplA) or lipoyl-[acyl-carrier-protein]-protein-N-lipoyltransferase (LipB), respectively, to lipoylate apo-pyruvate dehydrogenase complex (apo-PDC) [Jordan, S. W., and Cronan, J. E. (1997) Methods Enzymol. 279, 176-183]. When sodium dithionite-reduced LipA was incubated with octanoyl-ACP, LipB, apo-PDC, and S-adenosyl methionine (AdoMet), lipoylated PDC was formed. As shown by this assay, octanoic acid is not a substrate for LipA. Confirmation that LipA catalyzes formation of lipoyl groups from octanoyl-ACP was obtained by MALDI mass spectrometry of a recombinant PDC lipoyl-binding domain that had been lipoylated in a LipA reaction. These results provide information about the mechanism of LipA catalysis and place LipA within the family of iron-sulfur proteins that utilize AdoMet for radical-based chemistry.

Using remotely sensed data to identify areas at risk for hantavirus pulmonary syndrome.

The 1993 U.S. hantavirus pulmonary syndrome (HPS) outbreak was attributed to environmental conditions and increased rodent populations caused by unusual weather in 1991- 92. In a case-control study to test this hypothesis, we estimated precipitation at 28 HPS and 170 control sites during the springs of 1992 and 1993 and compared it with precipitation during the previous 6 years by using rainfall patterns at 196 weather stations. We also used elevation data and Landsat Thematic Mapper satellite imagery collected the year before the outbreak to estimate HPS risk by logistic regression analysis. Rainfall at case sites was not higher during 1992-93 than in previous years. However, elevation, as well as satellite data, showed association between environmental conditions and HPS risk the following year. Repeated analysis using satellite imagery from 1995 showed substantial decrease in medium- to high-risk areas. Only one case of HPS was identified in 1996.

Pyruvate formate-lyase-activating enzyme: strictly anaerobic isolation yields active enzyme containing a [3Fe-4S](+) cluster.

Pyruvate formate-lyase-activating enzyme (PFL-AE) from Escherichia coli (E. coli) catalyzes the stereospecific abstraction of a hydrogen atom from Gly734 of pyruvate formate-lyase (PFL) in a reaction that is strictly dependent on the cosubstrate S-adenosyl-l-methionine (AdoMet). Although PFL-AE is an iron-dependent enzyme, isolation of the enzyme with its metal center intact has proven difficult due to the oxygen sensitivity and lability of the metal center. We report here the first isolation of PFL-AE under nondenaturing, strictly anaerobic conditions. Iron and sulfide analysis as well as UV-visible, EPR, and resonance Raman data support the presence of a [3Fe-4S](+) cluster in the purified enzyme. The isolated native enzyme, but not apo-enzyme, exhibits a high specific activity (31 U/mg) in the absence of added iron, indicating that the native cluster is necessary and sufficient for enzymatic activity.

Preparation and initial characterization of the compound I, II, and III states of iron methylchlorin-reconstituted horseradish peroxidase and myoglobin: models for key intermediates in iron chlorin enzymes.

To better understand the spectral properties of high valent and oxyferrous states in naturally occurring iron chlorin-containing proteins, we have prepared the oxoferryl compound I derivative of iron methylchlorin-reconstituted horseradish peroxidase (MeChl-HRP) and the compound II and oxyferrous compound III states of iron MeChl-reconstituted myoglobin. Initial spectral characterization has been carried out with UV-visible absorption and magnetic circular dichroism. In addition, the peroxidase activity of iron MeChl-HRP in pyrogallol oxidation has been found to be 40% of the rate for native HRP. Previous studies of oxoferryl chlorins have employed tetraphenylchlorins in organic solvents at low temperatures; stable oxyferrous chlorins have not been previously examined. The present study describes the compound I, II, and III states of histidine-ligated iron chlorins in a protein environment for the first time.

Incidence of Rocky Mountain spotted fever among American Indians in Oklahoma.

OBJECTIVE: Although the state of Oklahoma has traditionally reported very high incidence rates of Rocky Mountain spotted fever (RMSF) cases, the incidence of RMSF among the American Indian population of the state has not been studied. The authors used data from several sources to estimate the incidence of RMSF among American Indians in Oklahoma. METHODS: The authors retrospectively reviewed an Indian Health Service (IHS) hospital discharge database for 1980-1996 and available medical charts from four IHS hospitals. The authors also reviewed RMSF case report forms submitted to the Centers for Disease Control and Prevention (CDC) for 1981-1996. RESULTS: The study data show that American Indians in the IHS Oklahoma City Area were hospitalized with RMSF at an annual rate of 48.2 per million population, compared with an estimated hospitalization rate of 16.9 per million Oklahoma residents. The majority of cases in the IHS database (69%) were diagnosed based on clinical suspicion rather than laboratory confirmation. The incidence of RMSF for Oklahoma American Indians as reported to the CDC was 37.4 cases per million, compared with 21.6 per million for all Oklahoma residents (RR 1.7, 95% confidence interval [CI] 1.5, 2.1). CONCLUSIONS: Rates derived from the IHS database may not be comparable to state and national rates because of differences in case inclusion criteria. However, an analysis of case report forms indicates that American Indians n Oklahoma have a significantly higher incidence of RMSF than that of the overall Oklahoma population. Oklahoma American Indians may benefit from educationa campaigns emphasizing prevention of tick bites and exposure to tick habitats.