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Biomedical subjects

R J Lewis

Publications and source records attributed to R J Lewis.

At least 91 records · Page 5Linked to original sources
PubMed1999

HPLC/tandem electrospray mass spectrometry for the determination of Sub-ppb levels of Pacific and Caribbean ciguatoxins in crude extracts of fish.

Ciguatera is a significant food-borne disease caused by potent polyether toxins (ciguatoxins) which accumulate in the flesh of ciguateric reef fish at risk levels > 0.1 ppb for Pacific ciguatoxins. Research on ciguatera has been severely hindered by the lack of analytical methods that detect and characterize low levels of ciguatoxin in crude extracts of fish. Here we report a new procedure for ciguatoxin analysis based on gradient reversed-phase HPLC/tandem mass spectrometry (HPLC/MS/MS). The method gave a linear response to pure Pacific and Caribbean ciguatoxins (P-CTX-1 and C-CTX-1) and the structurally related brevetoxin (PbTx-2) spiked into crude extracts of fish. Levels equivalent to 40 ppt P-CTX-1, 100 ppt C-CTX-1, and 200 ppt PbTx-2 in fish flesh could be detected by HPLC/MS/MS. Using P-CTX-1 as an internal standard, the analysis of extracts of 30 ciguateric fish from the Caribbean Sea (8 toxic, 12 borderline, and 10 nontoxic by mouse bioassay) confirmed the reliability of the method and allowed an estimated risk level of > 0.25 ppb C-CTX-1 to be established. HPLC/MS/MS provides a sensitive analytical approach, not previously available, for the determination of Pacific and Caribbean ciguatoxins at sub-ppb levels in fish flesh.

Animals↗
PubMed1999

Endovascular vs open abdominal aortic aneurysm repair: a comparison of cardiac morbidity and mortality.

HYPOTHESIS: Adverse cardiac event rates following endovascular abdominal aortic aneurysm (EAAA) and open abdominal aortic aneurysm (OAAA) repair are similar. We also hypothesized that the Eagle criteria (Q wave on electrocardiogram, diabetes, angina, congestive heart failure, age >70 years, and ventricular ectopy) are useful predictors of cardiac events in patients undergoing EAAA repair. DESIGN: Prospective (patients undergoing EAAA repair) and retrospective (patients undergoing OAAA repair). SETTING: Public teaching and Veterans Affairs medical centers. PATIENTS: Eighty-three EAAA and 63 OAAA repairs. MAIN OUTCOME MEASURES: Myocardial infarction, congestive heart failure, and cardiac death. RESULTS: Patients with EAAA were older (73 vs 68 years, P=.003). There were no differences in the mean number of Eagle criteria (1.2 vs 1.3), cardiac event rates (6% vs 4.8%), or mortalities (3.6% vs 4.8%). Within the EAAA group, congestive heart failure (P=.005) and Q wave on electrocardiogram (P=.006) were the only predictors of cardiac events. CONCLUSIONS: Patients undergoing OAAA and EAAA repair had similar cardiac event rates and mortality. In patients undergoing EAAA repair, history of congestive heart failure and Q wave on electrocardiogram were predictors of cardiac events.

Aged↗
PubMed1999

MMPI-2 profiles of NGRI and civil patients.

Limited information is available comparing individuals found Not Guilty by Reason of Insanity (NGRI) to other psychiatric patients. This study examined the MMPI-2 profiles of 36 NGRIs and 35 civilly committed inpatients at 3 state psychiatric hospitals. The NGRI and civil patient groups differed in terms of race and gender with more minority individuals and fewer women in the NGRI group. Therefore, these demographic variables were used as covariates in a MANCOVA comparing the MMPI-2 validity and clinical scales for these 2 groups. NGRIs and civil inpatients produced significantly different mean MMPI-2 profiles, with NGRIs reporting less pathology overall compared to civil inpatients. Specifically, NGRIs had lower scores on scales F, 1, 2, 7, 8, and O and higher scores on scale K. Contrary to expectations, NGRIs and civil patients did not differ on scale 4, supplementary scale Re, and content scales ANG, CYN, and ASP, or Harris-Lingoes subscale Pd2. Overall, these results suggest that NGRI patients are functioning at a higher level than civil patients. These findings are considered in terms of previous results and potential selection bias. Implications for treatment and future research are also considered.

Adult↗
PubMed1999

Cardiac morbidity and operative mortality following lower-extremity amputation: the significance of multiple Eagle criteria.

The ability of the Eagle criteria (age >70 years, angina, diabetes, Q wave on EKG, history of congestive heart failure) to predict adverse cardiac events following major vascular surgery has previously been demonstrated. However, the utility of these criteria for lower-extremity amputation is not well established. To determine the value of the Eagle criteria for predicting cardiac morbidity and operative mortality following major lower-extremity amputation, we reviewed 214 consecutive procedures performed at two institutions over a 3-year period. Mean age was 62.7 years and 85% of the patients were male. Diabetes was the most frequent Eagle criterion (74%). The mean number of Eagle criteria was 1.6. Fifty-six percent of the amputations were below the knee, 24% were above the knee, and 20% were guillotine. On multivariate regression analysis, the presence of two or more Eagle criteria (16% vs. 4%, p = 0.04) and decompensated heart failure (39% vs. 7%, p = 0.003) were predictive of adverse cardiac events. The only predictor of postoperative mortality was the presence of two or more Eagle criteria (15% vs. 4%, p = 0.004). Our evaluation of the results of this study led us to conclude that patients requiring major lower-extremity amputation for major vascular disease who have multiple Eagle criteria or decompensated congestive heart failure are at high risk for adverse cardiac events and postoperative death. These findings should be used to guide perioperative cardiac evaluation and therapy.

Aged↗
PubMed1999

Priorities for research in Emergency Medical Services for Children: results of a consensus conference. EMSC Research Agenda Consensus Committee, National EMSC Resource Alliance.

STUDY OBJECTIVE: The study objective was to arrive at a consensus on the priorities for future research in Emergency Medical Services for Children (EMSC). METHODS: A consensus group was convened using the Rand'-UCLA Consensus Process. The group took part in a 3-phase process. Phase I involved reviewing a compendium of relevant research articles and answering a mailed questionnaire. Panel members were asked to prioritize topics based on the 1993 Institute of Medicine Report on Emergency Medical Services for Children. Participants were asked to rate each topic based on the significance of the research and whether the topic would (1) improve general knowledge, (2) change behavior, (3) improve health, (4) decrease the cost of care, or (5) change public policy. A 4-point Likert scale was used. They were also asked in the research would require a multicenter study and if the research were feasible. Round II of the study involved a meeting of the panel, where the results of Round I were discussed and the topics reprioritized. The topics were given a rank order and a final ranking was done in Round III. RESULTS: The panel considered a list of 32 topics and these were combined and reworded to give them more precise meaning. Several new topics were also added. Fifteen topics were given a rank order and placed within the 7 broad categories of the Institute of Medicine report. Clinical aspects of emergency care systems organization, configuration and operation and injury prevention were given high priority rankings. The first 5 topics were very close in point-rank order. CONCLUSION: The panel was able to develop a list of important topics for future research in EMSC that can be used by foundations, governmental agencies, and others in setting a research agenda for EMSC.

Child↗
PubMed1999

Priorities for research in emergency medical services for children: results of a consensus conference.

STUDY OBJECTIVE: To arrive at a consensus on the priorities for future research in emergency medical services for children. METHODS: A consensus group was convened using the Rand-UCLA Consensus Process. The group took part in a 3-phase process. Round 1 involved reviewing a compendium of relevant research articles and answering a mailed questionnaire. Panel members were asked to prioritize topics on the basis of the 1993 Institute of Medicine Report on Emergency Medical Services for Children. Participants were asked to rate each topic based on the significance of the research, and whether the topic would (1) improve general knowledge, (2) change behavior, (3) improve health, (4) decrease the cost of care, or (5) change public policy. A 4-point Likert scale was used. Participants were also asked if the research would require a multicenter study and if the research were feasible. Round 2 of the study involved a meeting of the panel, where the results of Round 1 were discussed and the topics were reprioritized. The topics were given a rank order and a final ranking was done in Round 3. RESULTS: The panel considered a list of 32 topics; these were combined and reworded to give them more precise meaning. Several new topics were also added. Fifteen topics were given a rank order and placed within the 7 broad categories of the Institute of Medicine report. Clinical aspects of emergency care, systems organization, configuration, and operation and injury prevention were given high priority rankings. The first 5 topics were very close in point-rank order. CONCLUSION: The panel was able to develop a list of important topics for future research in emergency medical services for children that can be used by foundations, governmental agencies, and others in setting a research agenda for such services.

Child↗
PubMed1999

Lymphopoietic cancer and other major causes of death among petrochemical researchers: an update.

This study updates lymphopoietic cancer (LHC) mortality statistics and other major causes of death through 1992 for 13,188 petrochemical researchers employed between 1964 and 1986. Significant deficits of deaths were observed for all causes, all cancers, ischaemic heart disease and all external causes. The subcategory of 'all other LHC' was elevated among males in an exposure class containing scientists and engineers. This finding was statistically significant based on national but not state comparison rates. Poisson regression analyses showed that increasing exposure classes were not associated with LHC, but a relationship was noted for total years worked. A non-significant increase in breast cancer among females was also observed but was concentrated among the lowest exposure class. This study and other similar investigations suggest various subcategories of LHC deaths are marginally elevated among chemical researchers and engineers. Evidence for a work-related LHC hazard for this population, however, has not been identified.

Chemical Industry↗
PubMed1999

Priorities for research in emergency medical services for children: results of a consensus conference.

OBJECTIVE: To arrive at a consensus on the priorities for future research in emergency medical services for children. METHODS: A consensus group was convened using the Rand-UCLA Consensus Process. The group took part in a 3-phase process. Round I involved reviewing a compendium of relevant research articles and answering a mailed questionnaire. Panel members were asked to prioritize topics on the basis of the 1993 Institute of Medicine Report on Emergency Medical Services for Children. Participants were asked to rate each topic based on the significance of the research, and whether the topic would (1) improve general knowledge (2), change behavior (3), improve health (4), decrease the cost of care, or (5) change public policy. A 4-point Likert scale was used. Participants were also asked if the research would require a multicenter study and if the research were feasible. Round II of the study involved a meeting of the panel, where the results of Round I were discussed and the topics were reprioritized. The topics were given a rank order and a final ranking was done in Round III. RESULTS: The panel considered a list of 32 topics; these were combined and reworded to give them more precise meaning. Several new topics were also added. Fifteen topics were given a rank order and placed within the 7 broad categories of the Institute of Medicine report. Clinical aspects of emergency care, systems organization, configuration, and operation and injury prevention were given high priority rankings. The first 5 topics were very close in point-rank order. CONCLUSION: The panel was able to develop a list of important topics for future research in emergency medical services for children that can be used by foundations, governmental agencies, and others in setting research agenda for such services.

Child↗
PubMed1999

Crystallization of the regulatory and effector domains of the key sporulation response regulator Spo0A.

The key response-regulator gene of sporulation, spo0A, has been cloned from Bacillus stearothermophilus and the encoded protein purified. The DNA-binding and phospho-acceptor domains of Spo0A have been prepared by tryptic digestion of the intact protein and subsequently crystallized in forms suitable for X-ray crystallographic studies. The DNA-binding domain has been crystallized in two forms, one of which diffracts X-rays to beyond 2. 5 A spacing. The crystals of the phospho-acceptor domain diffract X-rays beyond 2.0 A spacing using synchrotron radiation.

Amino Acid Sequence↗
PubMed1999

Crystallization and preliminary x-ray diffraction studies of a Bowman-Birk inhibitor from Vigna unguiculata seeds.

A Bowman-Birk type trypsin/chymotrypsin inhibitor isolated from Vigna unguiculata seeds has been crystallized. Crystals were grown using the vapour-diffusion method at pH 4.0 using citrate/phosphate as a buffer and 30% saturated ammonium sulfate as precipitant. The crystals belonged to the monoclinic space group P2(1), with unit-cell parameters a = 32.4, b = 61.8, c = 32.9 A, beta = 114.5 degrees. The Matthews coefficient calculated assuming two molecules in the asymmetric unit was 1.95 A(3) Da(-1), which corresponds to a 37% solvent content. X-ray data were collected to 2.5 A resolution from a flash-frozen crystal. The structure was solved using the molecular-replacement method using tracy soybean inhibitor structure (PDB entry 1pi2) as a model.

Chymotrypsin↗
PubMed1999

An approach to community consultation prior to initiating an emergency research study incorporating a waiver of informed consent.

OBJECTIVES: In November 1996, the Food and Drug Administration (FDA) and the Department of Health and Human Services (DHHS) enacted rules allowing a narrow exception to the requirement for prospective informed consent when enrolling critically ill patients in clinical research studies of emergency treatments. These rules require that, prior to initiation of the study, the applicable institutional review board (IRB) assess the acceptability of the proposed research study to members of the community in which the research will be conducted. Specifically, the IRB must perform community consultation-a process during which community members learn about the proposed research and communicate their opinions regarding its acceptability to investigators or IRB representatives. The FDA and DHHS rules do not define specific acceptable methods for performing this community consultation. The objective of this study is to demonstrate the feasibility and utility of one proposed method for performing such community consultation. METHODS: Parents of children being seen for minor traumatic injuries in three pediatric EDs were asked to participate in a study regarding informed consent. After consent, an instructor described to the parent a prospective, randomized, placebo-controlled trial of phenytoin for the prophylaxis of posttraumatic seizures in children with severe closed head trauma. All parents were then asked whether they would have consented for their own child's participation, if their child had suffered such head injury. The parents were further asked to explain the reason(s) for their responses. RESULTS: Parents of 227 children (children's mean +/- SD age 8.0 +/- 4.8 years, 57% male) were interviewed. Sixty-six percent of parents (149/227) stated they would give consent for their child's participation. Of the 149 consenting parents, 85% (126/149) cited potential benefit to their child, 72% (107/149) cited potential benefit to other children, and 60% (90/149) cited furthering medical knowledge. Of the 78 nonconsenting parents (34% of total), 54% (42/78) cited fear of adverse effects, 39% (30/78) did not want their child to be a research subject in general, 27% (21/78) believed they needed to discuss participation with family members who were unavailable, and 26% (20/78) stated they were unable to decide unless they were in the actual situation. Parental ethnicity and household income were found to influence the consent decision, while the parent's gender, religion, language, and educational level were not associated with the consent decision. CONCLUSIONS: Community consultation regarding the acceptability of an emergency research protocol can be obtained via interview techniques in the ED. This methodology may allow investigators to obtain data on opinion from a targeted community for IRB consideration during the review of emergency research studies proposing a waiver of informed consent.

Adult↗
PubMed1999

Implementing the Food and Drug Administration's final rule for waiver of informed consent in certain emergency research circumstances.

In 1996, the Food and Drug Administration released its Final Rule for Waiver of Informed Consent in Certain Emergency Research Circumstances (the Final Rule). The Department of Health and Human Services (DHHS) also released an update of its regulations related to waiver of informed consent in emergency research. These new regulations allow resuscitation research to proceed with a waiver of informed consent under very narrow and specific clinical research circumstances. Waiving informed consent for research participation has profound ethical and scientific implications. However, in unpredictable life-threatening clinical situations for which current therapy is unproven or unsatisfactory, patients usually are unable to consent on their own behalf to participate in clinical trials of potentially beneficial but experimental interventions. Because of the time-dependent nature of most resuscitation interventions, it is usually not feasible to identify and contact the legally authorized representative who can speak on behalf of the patient within the presumed therapeutic window of the intervention under investigation. For such clinical trials to proceed, a waiver of informed consent is usually necessary. Patients who are critically ill or injured and unable to provide meaningful prospective informed consent because of their current life-threatening condition are vulnerable and require additional protections beyond those for research subjects who can speak on their own behalf. The Final Rule and the DHHS-updated regulations incorporate a number of additional patient safeguards that must occur if a clinical trial is to proceed with waiver of informed consent. Specific means of adequately meeting these requirements are not described in the regulations. Although this was intentional on the part of the federal regulators so that individual protocols and research environments would direct the development of these patient safeguards, the lack of specific guidance has led to confusion on the appropriate implementation of the new regulations. This article reviews some of the key concepts of the Final Rule, with suggestions on their purpose and meaning. It also reviews the studies that have been approved to date to proceed with waiver of informed consent, and offers suggestions for the process of implementing the requirements of the Final Rule for research involving patients who are unable to give prospective informed consent.

Clinical Protocols↗
PubMed1999

Statistical methodology: IX. survival analysis.

Survival analysis is a group of statistical methods used to analyze data representing the time to an event of interest, e.g., the duration of survival after an out-of-hospital cardiac arrest or the length of time a patient stays in the ED. Survival analysis properly accounts for patients who are lost to follow-up and for patients who have not yet experienced the event of interest at the end of the study's observation period (censored data). This article acquaints the reader with the terminology, methodology, and limitations of survival analysis. Specific methods discussed include life tables, the Kaplan-Meier product limit estimate, the log-rank test, and the multivariate Cox proportional hazards model.

Cardiopulmonary Resuscitation↗
PubMed1999

The clinical utility of the rectal-skin temperature difference in the assessment of young infants.

OBJECTIVE: Previous studies have suggested that the degree of difference between rectal temperature and peripheral skin temperature [rectal-skin temperature difference (RSTD)] is predictive of serious illness in young infants. The authors sought to determine the clinical utility of the RSTD in the outpatient evaluation of infants up to 2 months of age for serious infectious illness (SII). METHODS: Simultaneous rectal and skin (anterior mid-lower leg) temperatures were recorded for all infants < or = 2 months of age seen in the ED over a one-year period. The physician's clinical assessment, rectal temperature, skin temperature, laboratory results, and final diagnoses were also recorded. The RSTD (rectal temperature - skin temperature) was calculated for each infant. Final diagnoses were recorded and classified as SII or nonserious illness (NSI). Mean RSTD for each group was calculated and data were analyzed by the Wilcoxon rank sum test and multivariate regression model. RESULTS: A total of 601 infants [mean age of 28 days (range 2-65 days)] were enrolled. Nine percent (57 of 601) of infants had SII. Forty percent (23 of 57) of infants with SII were febrile, and 60% (34 of 57) were afebrile. The mean RSTD of febrile infants with SII was 5.8 +/- 1.7 degrees C (range 3.2-9.7 degrees C) and 5.3 +/- 1.4 degrees C (range 3.0-7.6 degrees C) for febrile infants with NSI. The mean RSTD of afebrile infants with SII was 4.8 +/- 1.8 degrees C (range 2-12.5 degrees C) and 4.4 +/- 1.5 degrees C (range 0.04-10.9 degrees C) for afebrile infants with NSI. The RSTD was not associated with SII in either febrile or afebrile infants (p > 0.05, Wilcoxon rank sum test). A multivariate logistic regression model of age, rectal temperature, and RSTD suggested an independent association of rectal temperature with SII (p < 0.0001), but none between age or RSTD and SII (p > 0.05). CONCLUSION: Once the rectal temperature is known, the RSTD is not a clinically useful test in the evaluation of young infants for serious infectious illness.

Body Temperature↗