Search PubMed⌕ Search

Biomedical subjects

K Nelson

Publications and source records attributed to K Nelson.

At least 55 records · Page 3Linked to original sources
PubMed2000

Patients with existing pressure ulcers admitted to acute care.

PURPOSE: This study describes the characteristics of patients with pressure ulcers present on admission to the hospital and predictors of pressure ulcer presence and severity. DESIGN: Prospective cohort study. SETTING AND SUBJECTS: Adults (n = 267) admitted to a Pacific Basin military hospital who were expected to stay more than 24 hours. INSTRUMENTS: Braden scale, portable vital sign machine, and pulse oximeter. METHODS: Pressure ulcer risk was evaluated and skin inspection was performed. Demographic, physiologic, and laboratory data were obtained. Medical history and patient acuity were recorded. RESULTS: Thirty-four of 267 subjects (12.8%) had a pressure ulcer. Most were male and white. Their mean age was 65.7 years; mean albumin level, 2.9 g/dL: mean hematocrit level, 31.9 vol%; mean oxygen saturation, 95.3 mm Hg; and mean hemoglobin level, 10.7 g/dL. The mean Braden scale score for subjects without ulcers on admission was 19.7, and it was 15.9 for those with ulcers (P < .05). Analysis of variance showed that subjects with pressure ulcers had a significantly lower albumin level, total lymphocyte count, hematocrit level, and hemoglobin level. These subjects were significantly older and had a longer hospital length of stay. Regression showed that albumin level, oxygen saturation, and length of stay (P < .01) accounted for 11.3% of the variance of pressure ulcer presence and that albumin level and length of stay (P < .001) accounted for 11.2% of the variance in ulcer severity. CONCLUSIONS: Poorer nutritional status and decreased oxygen perfusion were predictors of pressure ulcers on admission. Nutrition and length of stay were predictors of ulcer severity. Further research is warranted.

Aged↗
PubMed2000

Distortion product otoacoustic emission test performance when both 2f1-f2 and 2f2-f1 are used to predict auditory status.

The objective of this study was to determine whether distortion product otoacoustic emission (DPOAE) test performance, defined as its ability to distinguish normal-hearing ears from those with hearing loss, can be improved by examining response and noise amplitudes at 2 f1-f2 and 2f2-f1 simultaneously. In addition, there was interest in knowing whether measurements at both DPs and for several primary frequency pairs can be used in a multivariate analysis to further optimize test performance. DPOAE and noise amplitudes were measured at 2f1-f2 and 2 f2-f1 for 12 primary levels (L2 from 10 to 65 dB SPL in 5-dB steps) and 9 pairs of primary frequencies (0.5 to 8 kHz in 1/2-octave steps). All data were collected in a sound-treated room from 70 subjects with normal hearing and 80 subjects with hearing loss. Subjects had normal middle-ear function at the time of the DPOAE test, based on standard tympanometric measurements. Measurement-based stopping rules were used such that the test terminated when the noise floor around the 2 f1-f2 DP was < or = -30 dB SPL or after 32 s of artifact-free averaging, whichever occurred first. Data were analyzed using clinical decision theory in which relative operating characteristics (ROC) curves were constructed and areas under the ROC curves were estimated. In addition, test performance was assessed by selecting the criterion value that resulted in a sensitivity of 90% and determining the specificity at that criterion value. Data were analyzed using traditional univariate comparisons, in which predictions about auditory status were based only on data obtained when f2 = audiometric frequency. In addition, multivariate analysis techniques were used to determine whether test performance can be optimized by using many variables to predict auditory status. As expected, DPOAEs were larger for 2f1-f2 compared to 2 f2-f1 in subjects with normal hearing. However, noise amplitudes were smaller for 2f2-f1, but this effect was restricted to the lowest f2 frequencies. A comparison of signal-to-noise ratios (SNR) within normal-hearing ears showed that the 2f1-f2 DP was more frequently characterized by larger SNRs compared to 2f2-f1. However, there were several subjects in whom 2f2-f1 produced a larger SNR. ROC curve areas and specificities for a fixed sensitivity increased only slightly when data from both DPs were used to predict auditory status. Multivariate analyses, in which the inputs included both DPs for several primary frequency pairs surrounding each audiometric frequency, produced the highest areas and specificities. Thus, DPOAE test performance was improved slightly by examining data at two DP frequencies simultaneously. This improvement was achieved at no additional cost in terms of test time. When measurements at both DPs were combined with data obtained for several primary frequency pairs and then analyzed in a multivariate context, the best test performance was achieved. Excellent test performance (ROC) curve areas >0.95% and specificities >92% at all frequencies, including 500 Hz, were achieved for these conditions. Although the results described should be validated on an independent set of data, they suggest that the accuracy with which DPOAE measurements identify auditory status can be improved with multivariate analyses and measurements at multiple DPs.

Audiometry↗
PubMed2000

The work lives of women physicians results from the physician work life study. The SGIM Career Satisfaction Study Group.

OBJECTIVE: To describe gender differences in job satisfaction, work life issues, and burnout of U.S. physicians. DESIGN/PARTICIPANTS: The Physician Work life Study, a nationally representative random stratified sample of 5,704 physicians in primary and specialty nonsurgical care (N = 2,326 respondents; 32% female, adjusted response rate = 52%). Survey contained 150 items assessing career satisfaction and multiple aspects of work life. MEASUREMENTS AND MAIN RESULTS: Odds of being satisfied with facets of work life and odds of reporting burnout were modeled with survey-weighted logistic regression controlling for demographic variables and practice characteristics. Multiple linear regression was performed to model dependent variables of global, career, and specialty satisfaction with independent variables of income, time pressure, and items measuring control over medical and workplace issues. Compared with male physicians, female physicians were more likely to report satisfaction with their specialty and with patient and colleague relationships (P <.05), but less likely to be satisfied with autonomy, relationships with community, pay, and resources (P <.05). Female physicians reported more female patients and more patients with complex psychosocial problems, but the same numbers of complex medical patients, compared with their male colleagues. Time pressure in ambulatory settings was greater for women, who on average reported needing 36% more time than allotted to provide quality care for new patients or consultations, compared with 21% more time needed by men (P <.01). Female physicians reported significantly less work control than male physicians regarding day-to-day aspects of practice including volume of patient load, selecting physicians for referrals, and details of office scheduling (P <.01). When controlling for multiple factors, mean income for women was approximately $22,000 less than that of men. Women had 1.6 times the odds of reporting burnout compared with men (P <.05), with the odds of burnout by women increasing by 12% to 15% for each additional 5 hours worked per week over 40 hours (P <.05). Lack of workplace control predicted burnout in women but not in men. For those women with young children, odds of burnout were 40% less when support of colleagues, spouse, or significant other for balancing work and home issues was present. CONCLUSIONS: Gender differences exist in both the experience of and satisfaction with medical practice. Addressing these gender differences will optimize the participation of female physicians within the medical workforce.

Adult↗
PubMed2000

A contract research organization's response to the new FDA guidances for bioequivalence/bioavailability studies for orally administered drug products.

The new FDA Guidance for Industry BA and BE Studies for Orally Administered Drug Products--General Considerations and Average, Population, and Individual Approaches to Establishing Bioequivalence imply significant changes in the areas of enrollment, cost, ethics, time, entry, validation applications (EVAs), and statistical and pharmacokinetic methods. The changes from three-period to two-period design for food effect studies, the elimination of most steady state studies, and the analyses of only the active moiety or ingredient are welcome. However, if the current guidances are adopted, additional time will be needed for participants, and more participants will be needed, resulting in higher costs to drug developers. The PK parameters needed to assess BE and the need for replicate designs for drugs with long t1/2 are still unclear. Finally, the advantages of the aggregate property of the FDA metric versus the disaggregate criteria are challenged, and four bioequivalence criteria are proposed.

Administration, Oral↗
PubMed1999

Needle-exchange attendance and health care utilization promote entry into detoxification.

This study was undertaken to identify factors associated with entry into detoxification among injection drug users (IDUs), and to assess the role of needle-exchange programs (NEPs) as a bridge to treatment. IDUs undergoing semiannual human immunodeficiency virus (HIV) tests and interviews were studied prospectively between 1994 and 1998, during which time an NEP was introduced in Baltimore. Logistic regression was used to identify independent predictors of entry into detoxification, stratifying by HIV serostatus. Of 1,490 IDUs, similar proportions of HIV-infected and uninfected IDUs entered detoxification (25% vs. 23%, respectively). After accounting for recent drug use, hospital admission was associated with four-fold increased odds of entering detoxification for HIV-seronegative subjects. Among HIV-infected subjects, hospital admission, outpatient medical care, and having health insurance independently increased the odds of entering detoxification. After accounting for these and other variables, needle-exchange attendance also was associated independently with entering detoxification for both HIV-infected (adjusted odds ratio [AOR] = 3.2) and uninfected IDUs (AOR = 1.4). However, among HIV-infected subjects, the increased odds of detoxification associated with needle exchange diminished significantly over time, concomitant with statewide reductions in detoxification admissions. These findings indicate that health care providers and NEPs represent an important bridge to drug abuse treatment for HIV-infected and uninfected IDUs. Creating and sustaining these linkages may facilitate entry into drug abuse treatment and serve the important public health goal of increasing the number of drug users in treatment.

Adult↗
PubMed1999

Reliability of placental histology using archived specimens.

Archived placental materials provide a resource for retrospective studies of perinatal outcomes. Using archived specimens, we evaluated inter-rater reliability in the assessment of placental histological features possibly associated with neonatal illness and long-term neurological outcome. Five expert placental pathologists independently reviewed archived placental specimens on 30 subjects born during 1983-85 in six different hospitals. Moderate to substantial agreement among the raters was observed for a variety of indicators of inflammation, presence of macrophages with pigment and indicators of villous maturity, increased syncytial knots and maternal vasculopathy. Existing pathology reports for these specimens from routine histology examinations conducted at the time of delivery were in substantial agreement with expert review for the presence of any subchorionitis/chorionitis/chorioamnionitis. In conclusion, considerable inter-rater agreement was observed for several relatively common and potentially important placental findings. Archived placental materials and pathology reports may be useful in retrospective studies.

Cerebral Palsy↗
PubMed1999

Event representations, narrative development and internal working models.

In this article I summarize the theoretical framework of experientially based event representations as the basis for early cognitive development. Further work on representational levels, in particular the level of extended discourse such as narratives that incorporate new understandings of the personal, social and cultural world, is discussed. Parallels with the concept of internal working models from attachment theory, and differences between these two theoretical approaches are then laid out, with implications for further interchange between the two.

Adolescent↗
PubMed1999

Staphylococcus lugdunensis pulmonary valve endocarditis in a patient on chronic hemodialysis.

We describe a case of Staphylococcus lugdunensis pulmonary valve endocarditis in a 65-year-old woman on chronic hemodialysis and provide a review of previously reported cases. The patient presented with fever and altered mental status, but had no other localizing symptoms or signs; coagulase-negative staphylococcus (subsequently identified as S. lugdunensis) was isolated from two sets of blood cultures. Transthoracic and transesophageal echocardiograms showed a large (2.3 x 3.1 cm) vegetation on the pulmonary valve with moderate valvular insufficiency. The patient was treated with 6 weeks of antibiotic therapy and is stable 4 months following the completion of therapy; no surgical intervention was performed. Of the 28 previously reported cases of S. lugdunensis endocarditis, only 1 had previously survived with medical therapy alone. This is the 3rd case report of S. lugdunensis endocarditis in a patient on hemodialysis; the presumed portal of entry in this and previously reported cases was the vascular access device. Endocarditis due to this organism is characterized by a high mortality, rapid tissue destruction, and a predilection for native valves. Because the clinical outcome is much more favorable with valvular replacement, speciation of the organism assumes great importance in defining the therapeutic approach.

Aged↗
PubMed1999

Overview of phase II trials of MTA in solid tumors.

MTA (LY231514, multitargeted antifolate) represents a new class of folate antimetabolites and inhibits multiple enzymes in the purine and thymidine biosynthetic pathways, including thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide formyl transferase. Based on the results of phase I investigation, the dose and schedule of 600 mg/m2 administered intravenously every 21 days was selected to carry into the phase II setting. A number of phase II studies are completed or ongoing in a wide range of tumor types, and encouraging results have been observed in colorectal, breast, non-small cell lung, head and neck, bladder, and cervical cancers.

Antimetabolites, Antineoplastic↗
PubMed1999

Somatic growth and clinical manifestation in formula fed infants born to HIV--infected mothers during the first year of life.

This was a comparative study of the growth and clinical manifestation between infected and uninfected HIV infants both of whom were fed with a limited quantity of powder milk from birth until one year of age. HIV-infected pregnant women were enrolled from the second trimester or the beginning of the third trimester. After birth, infants had physical examinations, body weight and height were recorded at 2, 4, 6, 9 and 12 month visits. All mothers were given 7 kilograms of infant formula at each infant visit until the infant was one year old. Diagnosis for HIV infection in these infants was made by two positive concordant results of DNA PCR or RNA PCR or HIV RNA. One hundred and two infants were diagnosed for HIV status and 21.5 per cent were infected. The infected infants showed signs of malnutrition. From 2-4 months of age, the averages of their weights and heights were lower than those of non-infected infants. Abnormal clinical signs were found in most infected infants by the time they were 9-12 months old. In conclusion for the infants born to HIV- infected mothers, monitoring signs and symptoms including their weight and height from birth till 9-12 months old, is predictive of the infectious status of most infected infants. The administration and management of infant formula in a limited quantity to HIV infected mothers in upper northern provinces of Thailand is possible without causing abnormal infant growth.

Female↗
PubMed1998

Hunger in an adult patient population.

CONTEXT: Although clinical observations suggest that some patients experience hunger and food insecurity, there are limited data on the prevalence of hunger in adult patients. OBJECTIVE: To determine the prevalence of hunger and food insecurity in adult patients at an urban county hospital. DESIGN: Cross-sectional survey conducted in 1997. PATIENTS: The primary survey included all patients aged 18 years or older who were admitted to the medicine, surgery, and neurology services during a 2-week period, and all patients who attended the hospital's general medicine clinic during 1 week. A second survey included primary care patients who received insulin from the hospital pharmacy during a 1-month period. MAIN OUTCOME MEASURES: Rates of hunger and food insecurity. RESULTS: Of 709 eligible patients, 567 (participation rate, 80%) were interviewed in either the clinic (n=281) or hospital (n=286). An additional 170 patients who received insulin were interviewed by telephone (response rate, 75%). Of the primary sample, 68 (12%) respondents reported not having enough food, 75 (13%) reported not eating for an entire day, and 77 (14%) reported going hungry but not eating because they could not afford food. A total of 222 (40%) had received food stamps in the previous year and of those, 113 (50%) had their food stamps reduced or eliminated. Recipients whose food stamps had been eliminated or reduced were more likely to report not having enough food (18% vs 13%, P=.006), not eating for a whole day (20% vs 16%, P=.01), going hungry but not eating (20% vs 16%, P=.08), and cutting down on the size of meals or skipping meals (33% vs 27%, P=.01). In multivariate analysis, independent predictors of hunger included an annual income of less than $10000 (odds ratio [OR], 7.55; 95% CI, 3.01-18.92), drug use (OR, 3.56; 95% CI, 1.46-8.66), and a reduction in food stamp benefits (OR, 1.73; 95% CI, 1.01-2.96). Predictors of food insecurity included an annual income of less than $10000 (OR, 4.12; 95% confidence interval [CI], 1.98-8.58), drug use (OR, 2.11; 95% CI, 1.66-5.08), and a reduction in food stamps (OR, 2.02; 95% CI, 1.23-3.32). In addition, 103 (61%) patients in the sample of diabetics reported hypoglycemic reactions; 32 (31%) of these were attributed to inability to afford food. CONCLUSION: Hunger and food insecurity are common among patients seeking care at an urban county hospital.

Adult↗
PubMed1998

Diversification of subtype E human immunodeficiency virus type 1 env in heterosexual seroconverters from Northern Thailand.

The C2-V3 region of the human immunodeficiency virus (HIV)-1 env was determined from 15 northern Thailand seroconverters between 1993 and 1995. Similar sequences were also determined from 18 seroconverting injection drug users in Baltimore. All seroconverters from northern Thailand were infected with subtype E HIV-1 on the basis of env sequences. Intersubject viral DNA distances increased from 2.3% in asymptomatic HIV-1-infected subjects characterized between 1990 and 1992 to 7.8% in these more recent seroconverters from Thailand. On the other hand, sequences from 18 seroconverters from Baltimore had a mean intersubject distance of 13.2%. The genetic diversity within HIV-1 subtype E in seroconverters in Thailand has increased significantly but is still less than that observed in HIV-1 from seroconverters in the United States, where the epidemic of HIV-1 infection is more mature. These results suggest that continued monitoring of the molecular epidemiology of HIV-1 infection in Thailand will be important for HIV vaccine development and evaluation.

Amino Acid Sequence↗
PubMed1998

Magnesium sulfate and cerebral palsy in premature infants.

This article reviews clinical and experimental evidence as to whether magnesium sulfate, administered soon before premature birth, can reduce the high rate of cerebral palsy in tiny infants. Three observational studies have reported an association of magnesium sulfate with lower rate of cerebral palsy, whether treatment was for maternal preeclampsia or for tocolysis. One of these studies also noted a significant reduction in cognitive disability. In another study, no significant protective effect was seen except in a small subset of infants. Magnesium was neuroprotective in many but not all of a variety of experimental studies and has a variety of biologic effects that might account for benefit. All existing clinical studies had relatively small numbers of very premature infants. Although all attempted to control for possible confounders, such studies cannot provide definitive answers as to possible benefits or risks of magnesium therapy. Only randomized clinical trials are likely to resolve the question of whether a brief exposure to an agent which, in the American experience, is considered safe if administered with appropriate supervision, can reduce longterm neurologic disability in premature infants.

Animals↗
PubMed1998

An embryo-defective mutant of arabidopsis disrupted in the final step of biotin synthesis

Auxotrophic mutants have played an important role in the genetic dissection of biosynthetic pathways in microorganisms. Equivalent mutants have been more difficult to identify in plants. The bio1 auxotroph of Arabidopsis thaliana was shown previously to be defective in the synthesis of the biotin precursor 7, 8-diaminopelargonic acid. A second biotin auxotroph of A. thaliana has now been identified. Arrested embryos from this bio2 mutant are defective in the final step of biotin synthesis, the conversion of dethiobiotin to biotin. This enzymatic reaction, catalyzed by the bioB product (biotin synthase) in Escherichia coli, has been studied extensively in plants and bacteria because it involves the unusual addition of sulfur to form a thiophene ring. Three lines of evidence indicate that bio2 is defective in biotin synthase production: mutant embryos are rescued by biotin but not dethiobiotin, the mutant allele maps to the same chromosomal location as the cloned biotin synthase gene, and gel-blot hybridizations and polymerase chain reaction amplifications revealed that homozygous mutant plants contain a deletion spanning the entire BIO2-coding region. Here we describe how the isolation and characterization of this null allele have provided valuable insights into biotin synthesis, auxotrophy, and gene redundancy in plants.

Journal Article↗
PubMed1998

Clinical pharmacokinetics of vasodilators. Part I.

Understanding the mechanism of action and the pharmacokinetic properties of vasodilatory drugs facilitates optimal use in clinical practice. It should be kept in mind that a drug belongs to a class but is a distinct entity, sometimes derived from a prototype to achieve a specific effect. The most common pharmacokinetic drug improvement is the development of a drug with a half-life sufficiently long to allow an adequate once-daily dosage. Developing a controlled release preparation can increase the apparent half-life of a drug. Altering the molecular structure may also increase the half-life of a prototype drug. Another desirable improvement is increasing the specificity of a drug, which may result in fewer adverse effects, or more efficacy at the target site. This is especially important for vasodilatory drugs which may be administered over decades for the treatment of hypertension, which usually does not interfere with subjective well-being. Compliance is greatly increased with once-daily dosing. Vasodilatory agents cause relaxation by either a decrease in cytoplasmic calcium, an increase in nitric oxide (NO) or by inhibiting myosin light chain kinase. They are divided into 9 classes: calcium antagonists, potassium channel openers, ACE inhibitors, angiotensin-II receptor antagonists, alpha-adrenergic and imidazole receptor antagonists, beta 1-adrenergic agonist, phosphodiesterase inhibitors, eicosanoids and NO donors. Despite chemical differences, the pharmacokinetic properties of calcium antagonists are similar. Absorption from the gastrointestinal tract is high, with all substances undergoing considerable first-pass metabolism by the liver, resulting in low bioavailability and pronounced individual variation in pharmacokinetics. Renal impairment has little effect on pharmacokinetics since renal elimination of these agents is minimal. Except for the newer drugs of the dihydropyridine type, amlodipine, felodipine, isradipine, nilvadipine, nisoldipine and nitrendipine, the half-life of calcium antagonists is short. Maintaining an effective drug concentration for the remainder of these agents requires multiple daily dosing, in some cases even with controlled release formulations. However, a coat-core preparation of nifedipine has been developed to allow once-daily administration. Adverse effects are directly correlated to the potency of the individual calcium antagonists. Treatment with the potassium channel opener minoxidil is reserved for patients with moderately severe to severe hypertension which is refractory to other treatment. Diazoxide and hydralazine are chiefly used to treat severe hypertensive emergencies, primary pulmonary and malignant hypertension and in severe preeclampsia. ACE inhibitors prevent conversion of angiotensin-I to angiotensin-II and are most effective when renin production is increased. Since ACE is identical to kininase-II, which inactivates the potent endogenous vasodilator bradykinin, ACE inhibition causes a reduction in bradykinin degradation. ACE inhibitors exert cardioprotective and cardioreparative effects by preventing and reversing cardiac fibrosis and ventricular hypertrophy in animal models. The predominant elimination pathway of most ACE inhibitors is via renal excretion. Therefore, renal impairment is associated with reduced elimination and a dosage reduction of 25 to 50% is recommended in patients with moderate to severe renal impairment. Separating angiotensin-II inhibition from bradykinin potentiation has been the goal in developing angiotensin-II receptor antagonists. The incidence of adverse effects of such an agent, losartan, is comparable to that encountered with placebo treatment, and the troublesome cough associated with ACE inhibitors is absent.

Angiotensin II↗