Intensity and frequency functions of [14C]2-deoxyglucose labelling in the central nucleus of the inferior colliculus in the cat

The frequency organization of the central nucleus of the inferior colliculus (ICC) in the anesthetised cat was quantitatively mapped using [14C]2-deoxyglucose. From a standardised rostrocaudal region of the ICC, the position of peak selective labelling along the tonotopic axis closely conformed to the reported tonotopic organization of this nucleus. The position of the peak was found not to significantly change its position along the tonotopic axis with increasing stimulus intensity. However, the amplitude of peak uptake and width of selective labelling were shown to monotonically increase with increase in stimulus intensity. The increase in width of selective labelling, about the position of peak uptake, showed a slight asymmetry toward the high-frequency regions of the ICC. A 2-DG frequency-position function for the ICC, similar to that for the cochlea, enabled the width of 2-DG bands to be expressed in terms of their frequency spread along the tonotopic axis. This inturn enabled 2-DG tuning curves to be plotted which, when compared to electrophysiologically determined tuning curves, showed marked similarities. The minimum threshold and width (Q10) of these 2-DG tuning curves fell within the range reported for single units in the cat auditory pathway.

The three-dimensional frequency organization of the inferior colliculus of the cat: a 2-deoxyglucose study

The 3-dimensional (3-D) functional organization of the cat's inferior colliculus (IC) was examined using the 2-deoxyglucose method. Animals were dichotically stimulated with pure tone stimuli at an intensity of 80 dB SPL. Autoradiographic sections from these animals, cut in the three standard planes, were serially reconstructed to reveal the 3-D topography of the isofrequency sheets of labelling. In all 3-D reconstructions, the isofrequency sheets extend rostrocaudally through the IC with the rostral aspect of the sheet being situated more ventral than its caudal aspect. In the mediolateral dimensions, sheets are angled at between 40 degrees and 60 degrees to the horizontal, running from a dorsomedial to a ventrolateral position. The low-frequency sheets (0.5 and 2 kHz) are dorsolaterally convex and situated in the dorsolateral region of the IC. The 4 and 10 kHz isofrequency sheets have a helical structure and are situated in the mid-region of the IC. The high-frequency sheets (20 and 30 kHz) are dorsolaterally concaved and situated in the ventromedial region of the IC. The topography of these isofrequency sheets generally agree with, and extended our knowledge of, the tonotopic organization of the IC as derived from electrophysiological studies. The functional organization revealed by the 2-deoxyglucose method only partially correlated with the neural laminae in the anatomical models of the IC proposed by Rockel and Jones [J. Comp. Neurol. 147 (1973) 11-60] and Oliver and Morest [J. Comp. Neurol. 222 (1984) 237-264]. It is therefore concluded that the neural laminar organization of the IC may not be a necessary substrate for the tonotopic organization seen the IC.

Insect repellents: an overview

The optimal management of arthropod bites is prevention, and many over-the-counter insect repellents are available. Since first marketed in 1956, deet has remained the most effective repellent against mosquitoes, biting fleas, gnats, and chiggers. Permethrin is applied to clothing rather than to skin, and it is a better repellent against ticks than deet. The risk of serious side effects with the use of deet is slight; nevertheless, the lowest effective concentration should be used. The current, popular repellent agents (for adults and children) and their active ingredients are discussed. In addition, the Environmental Protection Agency guidelines for the safe use of insect repellents are supplied.

Necrotizing fasciitis: a case study

Necrotizing fasciitis (NF) is a disease characterized by the destruction of the skin, subcutaneous fat, and fascia, with or without inflammation of the muscle tissue. NF carries a mortality rate in excess of 50 percent in neonates. Rapid diagnosis and initiation of antibiotics, along with meticulous nursing care, can provide an acceptable outcome for the neonate. This article reviews the pathophysiology, diagnosis, and treatment of NF; presents a case study; and provides a nursing care plan that supports treatment of this disease process.

Unusual pathogen in a man with HIV infection

A 41-year-old man who had tested positive for HIV infection presented with cough, yellow sputum, fever, and chills of 10 days' duration. He was short of breath at rest and had a poor appetite. He did not have chest pain, bloody sputum, or weight loss.

The clinical value of serum ferritin tests in endurance athletes

OBJECTIVE

It is common practice to measure serum ferritin levels in endurance athletes because of the belief that low iron stores may compromise performance. The direct relationship between endurance performance and iron deficiency anemia is well known, but there are theoretical reasons to believe that endurance performance may be adversely affected by low iron stores even in the absence of frank anemia. The purpose of this article is to provide a critical review of the scientific evidence relating low iron stores to endurance performance.

DATA SOURCES

Medline was searched using MeSH for articles related to ferritin and endurance published since 1985. Additional references were reviewed from the bibliographies of the retrieved articles.

STUDY SELECTION

All clinical study designs were reviewed as well as relevant animal studies. Conclusions regarding endurance performance in humans were limited to data from clinical studies.

DATA EXTRACTION AND SYNTHESIS

In reviewing the literature, the relative strengths of the study designs were examined carefully. Particular attention of the effectiveness of each study in isolating ferritin as the key independent variable. Dependent measures of endurance capacity were also evaluated.

MAIN RESULTS

Eight studies isolated serum ferritin as the experimental variable. Only one study reported a significant improvement in endurance performance (time to exhaustion) in subjects with low ferritin levels treated with oral iron, but this finding may have been magnified by an unexplained decrease in time to exhaustion in the control group. Iron dosages differed in the studies reviewed. Two additional studies that reported increases in performance parameters following increases in ferritin were confounded by concomitant increases in hemoglobin levels.

CONCLUSIONS

Iron supplementation can raise serum ferritin levels, but increases in ferritin concentration, unaccompanied by increases in hemoglobin concentration, have not been shown to increase endurance performance. Of concern to the clinician is that athletes with low ferritin levels but hemoglobin in the low-normal range may have iron deficiency anemia responsive to iron supplementation. Low ferritin with hemoglobin in the mid- to upper normal range is at best a relative indication for iron supplementation: low ferritin with hemoglobin in the low normal range is a stronger, yet still relative, indication for iron supplementation in athletes.

Implementing national standards for cancer pain management: program model and evaluation

The purpose of this quasi-experimental (pre and posttest) study was to test a model pain management program (PMP) to implement the American Pain Society (APS) quality assurance standards for the management of acute and chronic cancer pain using a continuous quality improvement (CQI) approach to improve professionals' knowledge and skills, patient satisfaction, and to identify areas needing improvement. The sample consisted of 1210 nurse responses and 698 interviews of patients with pain during hospitalization at a major urban cancer center. The PMP provided a structure (standards), educational opportunities, and training in CQI methods. Outcome measures included a patient evaluation questionnaire and concerns checklist; nurse knowledge, attitude and barriers questionnaire; and focus groups to identify areas needing improvement. Significant improvements were found in patients' satisfaction, nurses' knowledge and attitude scores, and reductions in nurses' perceptions of barriers. Focus groups revealed the need for improved communication among disciplines about pain and better assessment of patients unable to self-report. The program met its goal of implementing the APS standards, educating nurses, and identifying "system" problems, and improving overall patient satisfaction.

I-131 localization in acute megakaryocytic leukemia

A case of acute megakaryocytic leukemia in a 13-month-old infant was encountered in whom an abnormal bone scan was associated with abnormal I-131 MIBG uptake in the femoral bone marrow. The normal platelet will take up MIBG and thus, uptake of this radiopharmeceutical by the malignant megakaryocyte, a platelet precursor, may be caused by the same mechanism.

Acute day hospitalization as an alternative to inpatient treatment

OBJECTIVE

This paper describes the administrative process by which the Ottawa General Hospital (OGH) closed 6 beds and used the staff and space resources thus released to set up an acute day hospital (ADH) for the treatment of 8 acutely ill psychiatric patients. Outcome data are presented on the first 160 patients admitted to the ADH.

METHODS

Demographic and clinical information including diagnostic (DSM-III-R; Global Assessment of Functioning [GAF]) and questionnaire data (Symptom Checklist-90 Revised [SCL-90R]; Beck Depression Inventory [BDI]; State-Trait Anxiety Inventory [STAI]; patient satisfaction) were obtained from 160 ADH patients at admission and discharge. Forty-two of these patients provided follow-up data 3 to 6 months postdischarge. The outcome of ADH patients was compared with that of a retrospectively obtained random sample (n = 100) of inpatients on selected diagnostic and demographic variables.

RESULTS

On clinician-rated and self-report clinical scales, ADH patients showed significant clinical improvement reflected in higher GAF scores and less psychological distress, depression, and anxiety at discharge relative to admission. There were no significant group differences in outcome indices except for shorter length of stay in the ADH group compared with inpatients. The ADH group rated the program highly in help received and quality of service. Short-term follow-up showed that gains made during treatment were maintained 3 to 6 months later.

CONCLUSIONS

These results show that a time-limited day hospital program is clinically effective for acutely ill psychiatric patients and leads to a more efficient use of inpatient resources. We believe that partial hospitalization for the treatment of acute psychiatric disorders may have wide application in psychiatric hospital practice.

Mechanisms responsible for dominant expression of human growth hormone gene mutations

Point mutations of the donor splice site of intron 3 of the human GH-1 gene cause autosomal dominant inherited isolated growth hormone deficiency (IGHD II). The mechanism by which a defect in one GH-1 allele results in GH deficiency is obscure. Previously reported reverse transcription-nested PCR data suggested an overexpression of the mutant GH-1 allele. We employed alternative methods to determine the relative expression of mutant (C for G at +1 of intron 3) and normal GH-1 allele. The use of a second round PCR primer bridging exons 2 and 3 and specific for normal GH-1 messenger ribonucleic acid (mRNA) indicated equal quantities in mutant and control cells. Large scale messenger RNA extraction from Epstein-Barr virus-transformed lymphoblasts permitted assay by ribonuclease protection. In normal pituitary, there were three GH-1 mRNA species. The variant lacking exon 3 comprised 5% of the total GH-1 mRNA. The proband's lymphoblasts contained equal amounts of mRNA with and without exon 3. Only normal GH-1 mRNA was detected in controls. Secreted GH, measured by enzyme-linked immunosorbent assay was present in equal concentrations in media from normal and mutant cells. Thus, GH-1 mRNA lacking exon 3 was expressed in proportion to the dosage of the mutant gene, and dominant effects on GH secretion were not observed in lymphoblasts. These findings are compatible with a dominant negative mechanism involving interaction between normal and mutant proteins in secretory vesicles of somatotropes.

New Zealand health care financing 'reforms' perceived ideological context

Health sector financing reforms that have been ongoing over the last decade in most developed countries are rooted in philosophical terms in the ideology of economic rationalism. The ideology suggests that it is possible to artificially create markets for activities in contexts where markets do not develop naturally, and that the creation of these artificial markets leads to resource allocations that are both more efficient and more equitable than historical arrangements. The application of the ideology to New Zealand's health sector has generated some benefit--for example, a more rational approach to influencing the decisions of self-interest health care providers; but it has also generated some costs--for example, on ideological grounds it has brought into question the non-market rationales for maintaining a national health service system.

Screening for Wilms' tumor in children with high-risk congenital syndromes: considerations for an intervention trial

Screening for cancer in children is uncommon. However, in children with congenital syndromes associated with Wilms' tumor, conditions exist that potentially make screening effective. This select population of children 1) are relatively easily identified; 2) have a high incidence of Wilms' tumor; 3) if identified before development of Wilms' tumor, may have a decrement in morbidity/mortality; and 4) are amenable to a simple and acceptable screening technology, renal sonography exams. Many clinicians have recommended screening for cancer in children with congenital syndromes associated with Wilms' tumor. However, neither costs nor effectiveness of such recommendations have been evaluated systematically. The strongest evidence for or against Wilms' tumor screening in this select population would be provided by a randomized screening trial. Prior to undertaking such a trial, the key parameters that dominate the cost and effectiveness of screening should be identified. Simulation models, such as cost effectiveness analysis, offer a starting point for deciding whether cancer screening is appropriate, and if so, under what set of conditions. We review basic conditions required for a successful screening trial in children with syndromes that are at increased risk of Wilms' tumor. We also discuss the use of cost-effectiveness analysis as a preliminary step in determining the feasibility of an intervention trial.

p300 is a component of an estrogen receptor coactivator complex

The estrogen receptor (ER) is a ligand-dependent transcription factor that regulates expression of target genes in response to estrogen in concert with other cellular signaling pathways. This suggests that the mechanism by which ER transmits an activating signal to the general transcription machinery may include factors that integrate these diverse signals. We have previously characterized the estrogen receptor-associated protein, ERAP160, as a factor that complexes with ER in an agonist-dependent manner. We have now found that the transcriptional coactivator p300 associates with agonist bound ER and augments ligand-dependent activation by ER. Our studies show that an ER coactivator complex involves a direct hormone-dependent interaction between ER and ERAP160, resulting in the recruitment of p300. In addition, antibodies directed against the cloned steroid receptor coactivator 1 (SRC1) recognize ERAP160. The known role of p300 in multiple signal transduction pathways, including those involving the second messenger cAMP, suggests p300 functions as a point of integration between ER and these other pathways.

Reverse transcriptase mutations in HIV-1-infected children treated with zidovudine

Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) mutations were detected in DNA from peripheral blood mononuclear cells from 11 of 12 HIV-1-infected children after 11-20 months of zidovudine monotherapy. The number of children with mutations detected at each codon were as follows: codon 41, 4; codon 67, 2; codon 70, 7; codon 215, 7; codon 219, 0. Codon 41 mutations were found only in the presence of a codon 215 mutation and in the absence of a codon 70 mutation. The codon 41/215 mutant combination was associated with decline in weight-for-age z score during therapy, weight < 10th percentile, CD4+ cell counts < 3rd percentile, and immune-complex dissociated HIV-1 p24 antigen (ICD p24 Ag) levels > 100 pg/ml. Patients developing the codon 70 mutation tended to have body weight > 30th percentile, CD4+ cell counts > 25th percentile, and ICD p24 Ag < 100 pg/ml. The codon 41 mutation was associated with clinical deterioration during a 6-month followup period.

Effect of pulsatility and hemodynamic power on recovery of renal function

Circulatory assist devices are used to treat patients awaiting cardiac transplantation to preserve life as well as to permit recovery of end-organ function. The efficacy of pulseless perfusion versus pulsatile perfusion in the recovery of end-organ function has not been fully determined. In this study, the efficacy of pulseless perfusion compared to pulsatile perfusion on the recovery of renal function after a 30 min period of normothermic ischemia was examined. Pigs were randomly assigned to four groups. In all groups, acute renal ischemia was induced by clamping both renal arteries for 30 min. Reperfusion for 120 min was performed using either pulsatile perfusion or pulseless perfusion at 65 +/- 1.6 mm Hg (Groups I [pulsatile] and II [pulseless]) and at 40 +/- 1.1 mm Hg (Groups III [pulsatile] and IV [pulseless]). After reperfusion, renal blood flow, hemodynamic power (pressure * flow: hemodynamic power), oxygen consumption (VO2), tissue ATP, and urine output (UO) in Groups I, II, and III were significantly higher than in Group IV (p < .01 by ANOVA). Histopathologic examinations were not significantly different between groups. Under hypotensive conditions, pulsatile perfusion improves hemodynamic power delivery to the organ compared to pulseless perfusion. These results suggest that a pulseless pump is acceptable as an assist device when normal flow or perfusion pressure is maintained.

Renal failure after two myocardial infarctions

A 60-year-old man was admitted to the hospital for elective cardiac catheterization. He had had two myocardial infarctions (MI) one and two months earlier. After the second MI, he had been treated with tissue plasminogen activator and heparin. Since then, his blood urea nitrogen concentration had increased from 20 to 63 mg/dL and his blood creatinine concentration from 1.2 to 9.2 mg/dL.