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Biomedical subjects

N White

Publications and source records attributed to N White.

At least 37 records · Page 2Linked to original sources
PubMed2000

Hypoglycemia in Beckwith-Wiedemann syndrome.

Beckwith-Wiedemann syndrome (BWS) is an overgrowth syndrome associated with macrosomia, macroglossia, abdominal wall defects, hypoglycemia in the neonatal period and embryonal cancers of infancy and early childhood. The frequency of hypoglycemia in this population is between 30% and 50%. The majority of infants with hypoglycemia will be asymptomatic and have resolution of the hypoglycemia within the first 3 days of life. Less than 5% will have hypoglycemia beyond the neonatal period requiring either continuous feeding or a partial pancreatectomy. The cause of hypoglycemia is unclear, but direct and indirect evidence supports a hyperinsulinemia as the major factor. Recent identification of the majority of genes associated with BWS in the 11p15 region and the genotype of persistent hyperinsulinemia hypoglycemia of childhood also in the 11p15 region may provide a molecular basis for hypoglycemia in BWS, particularly for the occasional patients with hypoglycemia requiring a partial pancreatectomy. Detailed genotype phenotype evaluations are needed and should provide an insight as to why patients with BWS have hypoglycemia.

Beckwith-Wiedemann Syndrome↗
PubMed2000

The influence of the composition of the nursing staff on primary bloodstream infection rates in a surgical intensive care unit.

OBJECTIVES: To determine the risk factors for acquisition of nosocomial primary bloodstream infections (BSIs), including the effect of nursing-staff levels, in surgical intensive care unit (SICU) patients. DESIGN: A nested case-control study. SETTING: A 20-bed SICU in a 1,000-bed inner-city public hospital. PATIENTS: 28 patients with BSI (case-patients) were compared to 99 randomly selected patients (controls) hospitalized > or =3 days in the same unit. RESULTS: Case- and control-patients were similar in age, severity of illness, and type of central venous catheter (CVC) used. Case-patients were significantly more likely than controls to be hospitalized during a 5-month period that had lower regular-nurse-to-patient and higher pool-nurse-to-patient ratios than during an 8-month reference period; to be in the SICU for a longer period of time; to be mechanically ventilated longer; to receive more antimicrobials and total parenteral nutrition; to have more CVC days; or to die. Case-patients had significantly lower regular-nurse-to-patient and higher pool-nurse-to-patient ratios for the 3 days before BSI than controls. In multivariate analyses, admission during a period of higher pool-nurse-to-patient ratio (odds ratio [OR]=3.8), total parenteral nutrition (OR=1.3), and CVC days (OR=1.1) remained independent BSI risk factors. CONCLUSIONS: Our data suggest that, in addition to other factors, nurse staffing composition (ie, pool-nurse-to-patient ratio) may be related to primary BSI risk. Patterns in intensive care unit nurse staffing should be monitored to assess their impact on nosocomial infection rates. This may be particularly important in an era of cost containment and healthcare reform.

Case-Control Studies↗
PubMed2000

Facial paralysis secondary to acute otitis media.

We describe a case of facial paralysis in a 19-month-old male recently diagnosed with acute otitis media. Results of his physical examination was remarkable for left-sided peripheral facial nerve palsy with an associated middle ear infection. Physicians should understand the etiology, pathophysiology, treatment options, and prognosis of facial palsy in association with otitis media.

Acute Disease↗
PubMed2000

Antimalarial bioavailability and disposition of artesunate in acute falciparum malaria.

The pharmacokinetic properties of oral and intravenous artesunate (2 mg/kg of body weight) were studied in 19 adult patients with acute uncomplicated Plasmodium falciparum malaria by using a randomized crossover design. A sensitive bioassay was used to measure the antimalarial activity in plasma which results from artesunate and its principal metabolite, dihydroartemisinin. The oral study was repeated with 15 patients during convalescence. The mean absolute oral bioavailability of the antimalarial agent in patients with acute malaria was 61% (95% confidence interval [CI], 52 to 70%). The absorption and elimination of oral artesunate were rapid, with a mean elimination half-life of antimalarial activity of 43 min (95% CI, 33 to 53 min). Following oral administration to patients with acute falciparum malaria, peak antimalarial activity in plasma and the area under the plasma concentration-time curve were approximately double those during convalescence and the apparent volume of distribution and clearance were approximately half those during convalescence (P < or = 0.005). Acute malaria is associated with a significant reduction in the clearance of artesunate-associated antimalarial activity.

Administration, Oral↗
PubMed2000

Cerebral malaria.

Cerebral malaria may be the most common non-traumatic encephalopathy in the world. The pathogenesis is heterogeneous and the neurological complications are often part of a multisystem dysfunction. The clinical presentation and pathophysiology differs between adults and children. Recent studies have elucidated the molecular mechanisms of pathogenesis and raised possible interventions. Antimalarial drugs, however, remain the only intervention that unequivocally affects outcome, although increasing resistance to the established antimalarial drugs is of grave concern. Artemisinin derivatives have made an impact on treatment, but other drugs may be required. With appropriate antimalarial drugs, the prognosis of cerebral malaria often depends on the management of other complications-for example, renal failure and acidosis. Neurological sequelae are increasingly recognised, but further research on the pathogenesis of coma and neurological damage is required to develop other ancillary treatments.

Adult↗
PubMed1999

Antimalarial drug resistance and combination chemotherapy.

Antimarial drug resistance develops when spontaneously occurring parasite mutants with reduced susceptibility are selected, and are then transmitted. Drugs for which a single point mutation confers a marked reduction in susceptibility are particularly vulnerable. Low clearance and a shallow concentration-effect relationship increase the chance of selection. Use of combinations of antimalarials that do not share the same resistance mechanisms will reduce the chance of selection because the chance of a resistant mutant surviving is the product of the per parasite mutation rates for the individual drugs, multiplied by the number of parasites in an infection that are exposed to the drugs. Artemisinin derivatives are particularly effective combination partners because (i) they are very active antimalarials, producing up to 10,000-fold reductions in parasite biomass per asexual cycle; (ii) they reduce malaria transmissibility; and (iii) no resistance to these drugs has been reported yet. There are good arguments for no longer using antimalarial drugs alone in treatment, and instead always using a combination with artemisinin or one of its derivatives.

Animals↗
PubMed1999

Epizootiology of Chlamydia infections in two free-range koala populations.

The prevalence of Chlamydia pecorum and Chlamydia pneumoniae infections in two free-range koala populations was assessed using genus-specific PCR combined with species-specific DNA probe hybridisation. Population A had a very high overall level of chlamydial infection (85%) with significantly more of these infections being due to C. pecorum (73%) compared to C. pneumoniae (24%). The second population had a much lower prevalence of infection (10%) with equal levels of both species. An important finding of this study was that. while five of 24 C. pecorum-infected koalas had clinical signs of the disease (both ocular and urogenital sites), none out of seven C. pneumoniae-infected koalas had signs of clinical disease. This suggests that C. pecorum may be the more pathogenic of the two chlamydial species infecting this host. The level of infection (assessed by intensity of the specific hybridisation signal) also differed between chlamydial species, with C. pecorum infections ranging from low to high grade whereas C. pneumoniae infections were always low grade. When the age of infected koalas was examined, 58% of young, sexually immature koalas were found to have C. pecorum infections, increasing to 100% of koalas in the older age groups. This suggests that, in this population at least, young koalas are readily infected with C. pecorum from their mothers. While the infection levels with C. pneumoniae were too low to be statistically significant, again, sexually immature koalas were found to be infected. The recent separation of chlamydial infections in koalas into two species is beginning to indicate different epizootiologies for koala C. pecorum compared to koala C. pneumoniae.

Age Factors↗
PubMed1999

Evidence of blood-brain barrier dysfunction in human cerebral malaria.

Patients infected with the malaria parasite Plasmodium falciparum may develop a diffuse reversible encephalopathy, termed cerebral malaria. It is unclear how the intraerythrocytic parasite, which sequesters in the cerebral microvasculature but does not enter the brain parenchyma, induces this neurological syndrome. Adhesion of parasitized red blood cells in the brain microvasculature is mediated by specific receptors on the host endothelium, including intercellular adhesion molecule (ICAM)-1, CD36 and CD31. Leucocyte binding to cerebral endothelial cells in culture induces intracellular signalling via ICAM-1. The hypothesis that parasitized red blood cells binding to receptors on cerebral endothelial cells causes changes in the integrity of the blood-brain barrier was tested. Immunohistochemistry was used to examine the blood-brain barrier in human cerebral malaria, with antibodies to macrophage and endothelial activation markers, intercellular junction proteins, and plasma proteins. The distribution of the cell junction proteins occludin, vinculin and ZO-1 were altered in cerebral malaria cases compared to controls. While fibrinogen was the only plasma protein detected in the perivascular space, there was widespread perivascular macrophage activation, suggesting that these cells had been exposed to plasma proteins. It was concluded that functional changes to the blood-brain barrier occur in cerebral malaria, possibly as a result of the binding of parasitized red blood cells to cerebral endothelial cells. These changes require further examination in vitro.

Adolescent↗
PubMed1999

A community-developed, community-based lead poisoning prevention program: Lead Awareness North Philly Style.

This work describes a demonstration/research project to implement and evaluate community-developed, community-based strategies that address childhood lead poisoning. The project will increase knowledge of childhood lead poisoning as an environmental health risk, as well as hazard, exposure, and outcome surveillance for lead as an environmental agent. At the end of the second year of this study the data indicate increased knowledge about lead poisoning and that more children are being tested for lead poisoning in the experimental census tracts (CTs), when compared with the control CTs, with lower lead levels.

Adult↗
PubMed1999

Serum markers for Down's syndrome in women who have had in vitro fertilisation: implications for antenatal screening.

To examine the Down's syndrome screening positive rate among in vitro fertilisation (IVF) pregnancies, we measured second trimester serum marker levels in singleton IVF pregnancies (cases) and in five non-IVF pregnancies (controls) matched to each case for gestational age, age of mother, and duration of storage of the serum sample. There were 151 IVF pregnancies in which alpha fetoprotein, unconjugated oestriol (uE3), free beta-human chorionic gonadotrophin (hCG) and total hCG were measured, 104 IVF pregnancies in which free alpha-hCG was measured, and 39 IVF pregnancies in which inhibin A was measured. Median uE3 levels were 6% lower (P = 0.003), median free beta-hCG 9% higher (P = 0.024), and median total hCG 14% higher (P = 0.026) in IVF pregnancies compared with controls. The screen positive rate in the IVF pregnancies (28%) was about twice as high as that in controls (17%). High hCG levels may be explained by progesterone remaining high in IVF pregnancies. The low uE3 levels remain unexplained. In Down's syndrome screening in IVF pregnancies hCG and uE3 values should be adjusted to avoid the high screen positive rate.

Biomarkers↗
PubMed1999

Long-term respiratory health effects of the herbicide, paraquat, among workers in the Western Cape.

OBJECTIVE: To evaluate the possible effects of paraquat spraying among workers on deciduous fruit farms in the Western Cape, South Africa. Paraquat is a commonly used herbicide world wide and is a well documented cause of pulmonary fibrosis in studies of laboratory animals and in humans after exposure to a high dose (usually accidental or as parasuicide). The respiratory effects of long term, low dose exposure to paraquat have not been fully evaluated. METHODS: A cross sectional study of 126 workers. Administered questionnaires generated information on exposure, respiratory symptoms, and potential confounding variables. Spirometry and gas transfer were measured and chest radiographs performed. Oxygen desaturation on exercise testing was by oximetry during a modified stage one exercise test. RESULTS: No association was found between long term exposure to paraquat and reported symptoms, spirometry (forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC) and gas transfer (TLCO and KCO) or chest radiography. Multivariate analysis showed a significant relation between measures of long term exposure to paraquat and arterial oxygen desaturation during exercise independent of short term exposure. CONCLUSION: Previous studies have not shown a significant relation between measures of exposure to paraquat and standard tests of lung function. Arterial oxygen desaturation during exercise represents a more sensitive test. The findings indicate that working with paraquat under usual field conditions is associated with abnormal exercise physiology in a dose dependent fashion independent of recent exposure and acute poisoning events.

Adult↗
PubMed1999

Malaria: new developments in treatment and prevention.

Malaria still kills some 0.5-2.5 million people per year in the tropics. Resistance to the cheap, most commonly used antimalarials continues to spread alarmingly and could outpace drug development. The artemisinin derivatives have had an important clinical impact both on the treatment of resistant falciparum malaria and on the incidence of disease in low-transmission areas. A few promising new antimalarials are being tested clinically but there is an imperative need for cheap, well-tolerated drugs that can be used in short courses, and for strategies to delay the onset of drug resistance. Bed nets have been shown to reduce the incidence of severe malaria in many areas but an effective vaccine is urgently needed.

Antimalarials↗
PubMed1998

Postoperative respiratory complications in ex-premature infants after inguinal herniorrhaphy.

BACKGROUND/PURPOSE: The duration of postoperative cardiorespiratory monitoring of premature infants after inguinal herniorrhaphy is uncertain. Prolonged observation requiring hospital admission may be unnecessary and increases costs. METHODS: This study was a retrospective review of 191 inguinal herniorrhaphies performed between 1993 and 1996 at the Hermann Children's Hospital. The authors reviewed their experience to identify factors associated with postoperative apnea and bradycardia and determine a safe period of observation. RESULTS: Among 191 elective inguinal herniorrhaphies performed, 57 (29.8%) were in expremature infants (< or =60 weeks postconception). Five (8.8%) infants either failed extubation or were unable to extubate (group 1). The average age for this group was 41.0 +/- 1.2 weeks compared with 47.2 +/- 1.0 (P = .06) for those who were successfully extubated (group II). Preoperative apnea-bradycardia was found in four (80%) infants in group I compared with 32 (61.5%) in group II (P = 0.67). All group I and 21 (40.4%, P = .09) group II infants with a history of preoperative apnea required intubation for an average of 24.4 +/- 7.8 days and 8.2 +/- 2.4 days, respectively (P = .04). American Society of Anesthesia (ASA) scores were 2.6 +/- 0.4 for group I compared with 1.8 +/- 0.1 for group 11 (P = .01). The use of both intraoperative narcotics (three [60%] in group I v six [12%] in group II, P = .01]) and vecuronium (four [80%] in group I v 16 [31%] in group II, P = .03) were significantly more common in group I infants. Operating room time was 46.4 +/- 4.1 minutes for group I compared with 60.6 +/- 3.9 minutes for group II (P = .27). Postoperative apnea-bradycardia occurred in all five group I infants and two (3.8%, P = .001) group II infants. Group II infants were treated successfully with supplemental oxygen. CONCLUSIONS: All instances of postoperative apnea-bradycardia and laryngospasm occurred within 4 hours after operation without significant differences between groups. The risk of postoperative cardiorespiratory distress requiring reintubation in premature infants who undergo inguinal herniorrhaphy is not insignificant (8.8%). The judicious use of narcotics and vecuronium, and limiting patient selection to those with ASA score of less than 3 may lessen the need for reintubation. When present cardiorespiratory distress occurs early; therefore we recommend outpatient inguinal herniorrhaphy as a safe and cost-effective choice.

Anesthetics↗
PubMed1998

Bayesian estimation of asthma prevalence, and comparison of exercise and questionnaire diagnostics in the absence of a gold standard.

PURPOSE: To estimate the sensitivities, specificities, and predictive values of exercise challenge and questionnaire, when these tests are used to diagnose asthma in children. METHODS: Participants were children, predominantly aged 6 to 12 years, selected from three primary school grades among 18 different schools in Montreal. Of 1111 participants, 989 successfully completed a six-minute free running test at school and returned a respiratory questionnaire. A total of 952 children had complete information that could be used for analysis. A history of wheezing in the past year in conjunction with a past diagnosis of asthma defined current asthma by questionnaire. Exercise responsiveness was defined as a > or = 10% fall in FEV1 after a six-minute free run. As there is no perfectly accurate diagnostic test for asthma, we analyzed the data using a previously published Bayesian method that allows for the estimation of test properties when no gold standard test is available. RESULTS: Current asthma by questionnaire was found to have significantly higher specificity (94.9%, 95% credible interval (CI): 93.2-96.5 versus 82.6%, 95% CI: 79.9-85.1) and positive predictive value (53.8%, 95% CI: 41.0-66.7 versus 19.2%, 95% CI: 12.3-27.8) in comparison to exercise challenge. While there was no statistically significant difference between the two tests with respect to sensitivity and negative predictive values, the estimates were higher for current asthma (64.4%, 95% CI: 50.9-76.6 and 96.7%, 95% CI: 94.6-98.1, respectively) in comparison to exercise challenge (51.3%, 95% CI: 37.8-64.5 and 95.4%, 95% CI: 93.2-97.1, respectively). Agreement between the two diagnostic methods was poor and the combined use of the two tests did not significantly improve the likelihood of correctly identifying children with asthma. CONCLUSIONS: Our findings support the view that exercise testing adds little to a well designed questionnaire in identifying subjects with asthma in community based studies.

Asthma↗
PubMed1998

Are older women offered adequate health care?

The "graying of America" will have profound effects on the health care delivery system. With shrinking amounts of health care dollars, nurses and primary care providers need to promote health maintenance and disease prevention strategies that will foster healthier aging. This study was designed to examine the health promotion strategies of family practice physicians and residents. The target population was a sample of 201 women age 60 and older. The health maintenance issues were counseling about hormone replacement therapy (HRT), urinary incontinence (UI), and immunizations. The results clearly demonstrated that older women were not adequately immunized or counseled about HRT or UI. Nurses can play a pivotal role in changing these practices. Nurses can serve as advocates for older woman by encouraging them to request these services, or advanced practice nurses can provide these services.

Aged↗