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Biomedical subjects

D Richardson

Publications and source records attributed to D Richardson.

At least 73 records · Page 4Linked to original sources
PubMed2000

Intrapartum fever and unexplained seizures in term infants.

OBJECTIVE: Early-onset neonatal seizures are a strong predictor of later morbidity and mortality in term infants. Although an association of noninfectious intrapartum fever with neonatal seizures in term infants has been reported, it was based on only a small number of neonates with seizures. We therefore conducted a case control study to investigate this association further. METHODS: All term infants with neonatal seizures born at Brigham and Women's Hospital between 1989 and 1996 were identified. For this study, cases consisted of all term neonates with a confirmed diagnosis of seizure born after a trial of labor for whom no proximal cause of seizure could be identified. Infants with sepsis or meningitis were excluded. Four controls matched by parity and date of birth were identified for each case. The rate of intrapartum maternal temperature >100.4 degrees F was compared for case infants and controls. Potential confounding was controlled in logistic regression analysis. RESULTS: Cases comprised 38 term infants with unexplained seizures after a trial of labor. We identified 152 controls. Infants with seizures were more likely to be born to mothers who were febrile during labor (31.6% vs 9.2%). In almost all cases, the fever developed during labor (94.7% cases, 97.4% controls). At admission, mothers of infants with seizures were not significantly more likely to have factors associated with concern about infection such as a white blood cell count >15 000/mm(3) (28. 9% vs 19.1%) and premature rupture of the membranes (15.8% vs 17.8%). In a logistic regression analysis controlling for confounding factors, intrapartum fever was associated with a 3.4-fold increase in the risk of unexplained neonatal seizures (odds ratio = 3.4, 95% confidence interval = 1.03-10.9). CONCLUSION: Our data indicate that intrapartum fever, even when unlikely to be caused by infection, is associated with a fourfold increase in the risk of unexplained, early-onset seizures in term infants.

Adult↗
PubMed2000

Aetiology of nasopharyngeal glioma.

A case of nasopharyngeal glioma is presented in which the postnatal scans clearly show intracranial communication, whilst subsequent scans and surgical exploration could not demonstrate this finding. This case seems to confirm that the aetiology of these lesions is due to an encephalocele that subsequently loses its connection with the brain.

Brain↗
PubMed1999

Evidence for lateral gene transfer between Archaea and bacteria from genome sequence of Thermotoga maritima.

The 1,860,725-base-pair genome of Thermotoga maritima MSB8 contains 1,877 predicted coding regions, 1,014 (54%) of which have functional assignments and 863 (46%) of which are of unknown function. Genome analysis reveals numerous pathways involved in degradation of sugars and plant polysaccharides, and 108 genes that have orthologues only in the genomes of other thermophilic Eubacteria and Archaea. Of the Eubacteria sequenced to date, T. maritima has the highest percentage (24%) of genes that are most similar to archaeal genes. Eighty-one archaeal-like genes are clustered in 15 regions of the T. maritima genome that range in size from 4 to 20 kilobases. Conservation of gene order between T. maritima and Archaea in many of the clustered regions suggests that lateral gene transfer may have occurred between thermophilic Eubacteria and Archaea.

Archaea↗
PubMed1999

Infusion therapy team and dressing changes of central venous catheters.

OBJECTIVE: To determine whether central venous catheter (CVC) dressing changes could be performed by ward nurses rather than by the infusion therapy team (ITT) nurses without increasing the risk of catheter-related infection. DESIGN: Retrospective cohort study using prospectively collected data. The study extended from January 1995 to June 1996. SETTING: The University of Texas M.D. Anderson Cancer Center, a referral cancer center. PATIENTS: The study group was a random sample of 483 patients who received CVC dressing changes by ward nurses during the study period. A random sample of 483 patients who received CVC dressing changes by the ITT constituted the control group. RESULTS: The risks of catheter-related septicemia were 1.7% among cases and 1.4% among controls (risk ratio, 1.14; 95% confidence interval [CI95], 0.26-6.42; P=.70). There also were no significant differences between the two groups in the risks of catheter-related site infection (risk ratio, 0.50; CI95, 0.02-4.12; P=.25) or any catheter-related infection (risk ratio=1.00; CI95, 0.27-3.64; P=.59). CONCLUSIONS: Provided that aseptic techniques (including maximal barrier precautions during insertion) are maintained, the responsibility of CVC dressing changes could be delegated to the ward nurses without increasing the low risk of CVC-related infection, resulting in an estimated cost saving in excess of $90,000 per year.

Adult↗
PubMed1999

Undergraduate students' misconceptions about respiratory physiology.

Approximately 700 undergraduates studying physiology at community colleges, a liberal arts college, and universities were surveyed to determine the prevalence of our misconceptions about respiratory phenomena. A misconception about the changes in breathing frequency and tidal volume (physiological variables whose changes can be directly sensed) that result in increased minute ventilation was found to be present in this population with comparable prevalence (approximately 60%) to that seen in a previous study. Three other misconceptions involving phenomena that cannot be experienced directly and therefore were most likely learned in some educational setting were found to be of varying prevalence. Nearly 90% of the students exhibited a misconception about the relationship between arterial oxygen partial pressure and hemoglobin saturation. Sixty-six percent of the students believed that increasing alveolar oxygen partial pressure leads to a decrease in alveolar carbon dioxide partial pressure. Nearly 33% of the population misunderstood the relationship between metabolism and ventilation. The possible origins of these respiratory misconceptions are discussed and suggestions for how to prevent and/or remediate them are proposed.

Adolescent↗
PubMed1999

Coronary endothelial function is preserved with chronic endothelin receptor antagonism in experimental hypercholesterolemia in vitro.

Hypercholesterolemia is associated with increased circulating and tissue endothelin-1 immunoreactivity, decreased nitric oxide (NO) activity, and altered endothelial function. We tested the hypothesis that chronic endothelin receptor antagonism preserves endothelial function and increases NO in experimental porcine hypercholesterolemia. Pigs were randomized to 3 groups: Group 1, a 2% high-cholesterol (HC) diet alone (n=7); group 2, RO-48-5695, a combined endothelin receptor antagonist, and an HC diet (n=8); and group 3, ABT-627, a selective endothelin-A receptor antagonist, and an HC diet (n=8). Coronary epicardial and arteriolar endothelial function was determined by a dose-response relaxation to bradykinin (10(-11) to 10(-6) mol/L), in all groups and in pigs maintained on a normal diet. Plasma total oxidized products of NO (NO(x)) were determined by chemiluminescence at baseline and after 12 weeks. Bradykinin-stimulated coronary epicardial and arteriolar relaxation in group 1 was attenuated compared with normal-diet controls. This relaxation was normalized with endothelin receptor antagonism. Plasma NO(x) decreased after 12 weeks in group 1 (-74.8+/-5.5%). This decrease was attenuated in the endothelin receptor antagonist groups (group 2, -28.2+/-15.0%; group 3, -38.9+/-20.6%). Chronic endothelin receptor antagonism preserves coronary endothelial function and increases NO in hypercholesterolemia. This study supports a role of endothelin-1 in the regulation of NO activity and suggests a possible therapeutic role for endothelin receptor antagonists in hypercholesterolemia.

Animals↗
PubMed1999

The relevance of occupational epidemiology to radiation protection standards.

Large-scale epidemiological studies of U.S. Department of Energy workers have been underway since the 1960s. Despite the increasing availability of information about long-term follow-up of badge-monitored nuclear workers, standard-setting bodies continue to rely on the Life Span Study (LSS) of A-bomb survivors as the primary epidemiological basis for making judgments about hazards of low-level radiation. Additionally, faith in the internal and external validity of studies of A-bomb survivors has influenced decisions about the design, analysis, and interpretation of many worker studies. A systematic comparison of the LSS and worker studies in terms of population characteristics, types of radiation exposures, selection factors, and dosimetry errors suggests that the priority given to dose response findings from the LSS is no longer warranted. Evidence from worker studies suggests that excess radiation-related cancer deaths occur at doses below the current occupational limits; low-dose effects have also been seen in studies of childhood cancers in relation to fetal irradiation. These findings should be considered in revising current radiation protection standards.

Journal Article↗
PubMed1999

Risk adjustment for quality improvement.

We can learn what is achievable with current technologies by comparing our neonatal intensive care unit outcomes with others. Because neonatal intensive care units may vary with respect to their case-mix, risk adjustment is essential to making fair comparisons in any research that does not equalize risks through randomization. Risk adjustment first requires strict definition of each specific outcome. Then each risk factor is measured and weighted accordingly. Severity of illness scores are a special form of risk adjustment. The leading newborn illness severity scores rely on physiology-based items from bedside vital signs and laboratory tests. The mechanics of score development are discussed including item selection, definition, collection, and potential biases. The process of weighting risk factors usually involves building multivariate models. Issues of derivation, validation, discrimination, calibration, and reliability affect the utility of all scores. Once a comparison is appropriately risk-adjusted, there are important cautions about interpretation, including the source of the reference (benchmark) population, sample size, and biases from incomplete risk adjustment. Nonetheless, these findings can spur quality improvement efforts that can lead to dramatic, system-wide improvements in outcomes.

Benchmarking↗
PubMed1998

Complete genome sequence of Treponema pallidum, the syphilis spirochete.

The complete genome sequence of Treponema pallidum was determined and shown to be 1,138,006 base pairs containing 1041 predicted coding sequences (open reading frames). Systems for DNA replication, transcription, translation, and repair are intact, but catabolic and biosynthetic activities are minimized. The number of identifiable transporters is small, and no phosphoenolpyruvate:phosphotransferase carbohydrate transporters were found. Potential virulence factors include a family of 12 potential membrane proteins and several putative hemolysins. Comparison of the T. pallidum genome sequence with that of another pathogenic spirochete, Borrelia burgdorferi, the agent of Lyme disease, identified unique and common genes and substantiates the considerable diversity observed among pathogenic spirochetes.

Bacterial Proteins↗
PubMed1998

Simple, new device for needle aspiration biopsy.

Vertigo and dizziness are not common in childhood, but are probably present more often than was formerly thought. These symptoms caused mainly by o700is media and middle ear effusion, two of the most common diseases in children, have been neglected for a long time, both in the literature and in practice, until recently. The purpose of this study was to determine objectively the incidence of balance-related symptoms in children with long-lasting middle ear effusion and to discover whether these symptoms resolve after the insertion of ventilation tubes. One hundred thirty-six children, ages 4 to 9 years, were given electronystagmographic tests and the Bruininks-Oseretsky tests for motor proficiency before and after tube ventilation of the middle ear. The results were compared with those in 74 healthy children with no history of middle ear diseases. Pathologic findings were found in 58% of the children with chronic middle ear effusion, as compared with only 4% of the control group. The symptoms and signs of balance disturbances resolved in 96% of the children after ventilation tube insertion. The results of this study indicate that balance-related symptoms often encountered in young children may result from chronic middle ear effusion and that these symptoms will resolve after evacuation of the effusion and ventilation of the middle ear.

Adult↗
PubMed1998

Adult respiratory distress syndrome after microvascular free tissue reconstruction in head and neck malignancy.

Adult respiratory distress syndrome (ARDS) is an important cause of morbidity and mortality after major operations. We undertook a 10 year retrospective analysis of patients undergoing major surgery in combination with microvascular free tissue transfer for head and neck malignancy at a Regional Maxillofacial Unit to try and identify predisposing factors. In the 10 year period to 31 April 1995, roughly 418 patients underwent major head and neck reconstructions, of which 399 (95.5%) were admitted to the intensive care unit (ICU) postoperatively. Thirty patients (7.2%) spent more than 72 h in the ICU, eight developed ARDS (1.9%) of whom four died. The factors that seemed to contribute to the development of ARDS were massive blood transfusion and early postoperative complications that required a further operation under general anaesthesia.

Adult↗
PubMed1998

Continuous venovenous high-flux dialysis in multiorgan failure: a 5-year single-center experience.

The objective of this study was to determine the outcome of acute renal failure (ARF) treated by continuous venovenous high-flux dialysis in patients with ventilator-dependent respiratory failure treated in a single center and to examine the importance of primary diagnosis in determining survival. We retrospectively reviewed 408 consecutively treated patients in the multidisciplinary intensive care unit (ICU) of a large teaching hospital. All ventilated patients requiring dialysis support over a 5-year period (January 1, 1991 to December 31, 1995) were included in the study. Patient age, APACHE II score, primary diagnosis, inotrope requirement, and survival to discharge from the ICU, from the hospital, and at 6 months were recorded for 408 consecutively treated patients. The mean age was 54 years, the median APACHE II score was 29, and the ICUs, hospital, and 6-month survival rates were 48%, 38%, and 36%, respectively. Inotropic support was required in 75%. Liver disease was the primary diagnosis in 35%. Logistic regression analysis indicated that increasing age and APACHE II, use of inotropes, and presence of liver disease were all associated with increased mortality. Eight percent of survivors (3% of the total population) required long-term renal replacement therapy. In conclusion, in our experience, continuous venovenous high-flux dialysis can be universally adopted in the ICU management of ARF associated with multiorgan failure. Patient survival is related to primary diagnosis, and a knowledge of case mix is essential in considering outcome of ARF in any reported series.

APACHE↗