Physical activity patterns in chronic hemodialysis patients: comparison of dialysis and nondialysis days.

OBJECTIVE: To determine physical activity patterns in chronic hemodialysis patients with a specific emphasis on the difference between dialysis and nondialysis days. Design A cross-sectional single-center study. SETTING: Vanderbilt University Outpatient Dialysis Unit. PATIENTS: Twenty current chronic hemodialysis patients: 10 male, 10 female; 15 black, 5 white; mean age, 50.1 +/- 9.9 years; height, 164.5 +/- 10.9 cm; weight, 82.5 +/- 15.4 kg; length on dialysis, 57.3 +/- 45.3 months. METHODS: Minute-by-minute physical activity was assessed over a 7-day period using a triaxial accelerometer, which consists of raw numbers or counts calculated by the 3 axes of the accelerometer (PA counts). PA counts were extrapolated on a daily and hourly basis. Physical functioning tests included: sit-to-stand, 6-minute walk, and 1-repetition maximal leg press exercise. Laboratory values for serum concentrations of albumin, prealbumin, C-reactive protein, and cholesterol were also collected. MAIN OUTCOME MEASURE: PA counts. RESULTS: Total PA counts were significantly lower on dialysis days when compared with nondialysis days (128,279 +/- 74,009 versus 168,744 +/- 95,168, respectively, P = .025). The average PA counts during the 4-hour dialysis time period were significantly lower on dialysis days when compared with nondialysis days (3,086 +/- 3,749 versus 11,070 +/- 7,695, respectively, P = .001). At postdialysis hours 1 and 2, PA counts on dialysis days were significantly higher than on nondialysis days (11,410 +/- 5,340 versus 9,082 +/- 6,646, P = .008, and 14,048 +/- 9,728 versus 8,662 +/- 6,433, P = .016, respectively). By postdialysis hour 4, PA counts on dialysis days had significantly decreased when compared with nondialysis days (6,068 +/- 6,268 versus 10,512 +/- 7,420 PA counts, P = .01, respectively). From postdialysis hours 5 to 20, there was no significant difference in PA counts between dialysis and nondialysis days. CONCLUSION: This study shows that physical activity is lower on dialysis days when compared with nondialysis days, and this decrease is caused by the lack of activity during the 4-hour hemodialysis procedure. New behavior modification strategies involving physical activity, both during hemodialysis and on nondialysis days, must be examined in this patient population.     

Computed radiography in musculoskeletal imaging: state of the art.

Computed radiography is a 2K x 2K x 10 bit digital radiographic system that replaces the film-screen combination with a photo-stimulable phosphor plate. The advantages of this relatively new technology include linear detector response, improved detector efficiency, and digital processing capabilities. Musculoskeletal applications benefit significantly from these attributes, which result clinically in the ability to reduce both radiation dose and number of exposures. Studies of observers' performance have shown no statistically significant difference in diagnostic accuracy between film-screen and computed radiographic musculoskeletal images. Computed radiography is particularly useful in the evaluation of the musculoskeletal system in traumatized patients with portable radiographs, spine radiographs, scoliosis studies, and depiction of soft-tissue abnormalities. Limitations include change in image format and size, high cost, decreased spatial resolution, restricted throughput, increased perception of noise, and new artifacts that must be recognized. Spatial resolution limitations of computed radiography in identification of fine detail information can be improved by using magnification techniques. Radiation dose reduction with an exposure decrease of 25-50% can be achieved without loss of diagnostic accuracy, although this depends on the examination and the abnormality. An interactive workstation is important in the use of a computed radiographic system with capabilities to adjust display parameters to best depict images and disease. We conclude that computed radiography is an alternative to film-screen radiography without significant differences in diagnostic quality in the evaluation of musculoskeletal images.     

Biological characteristics of newly diagnosed poor prognosis acute myelogenous leukemia

A pilot study was conducted of the biological characteristics of the leukemia cells of newly diagnosed patients with poor prognosis acute myelogenous leukemia (AML). This study included measurements of the pretherapy proliferative rate of the leukemia cells in vivo, assessment of differentiation in vivo during remission induction therapy, and the level of expression of the fms, myc, and IL1β genes in pretherapy leukemia cells. Short cell cycle times were characteristic of the best prognostic category and were associated with a rapid reduction in marrow leukemia cells in cytosine arabinoside (araC)-sensitive patients. Expression of c-fms was associated with rapid reduction in marrow leukemia cells during araC therapy and with a successful treatment outcome. Expression of the IL1β gene was associated with short remissions. These studies suggest that when compared to newly diagnosed standard prognosis AML, the leukemia of poor prognosis patients is more likely to exhibit long cell cycle times, low levels of fms expression, and is less likely to be associated with myeloid differentiation during remission induction therapy. © 1993 Wiley-Liss, Inc.     

Visuospatial impairments in aged canines (Canis familiaris): the role of cognitive-behavioral flexibility

This study used a novel delayed nonmatching-to-position task to compare visuospatial learning and memory in young and aged beagle dogs (Canis familiaris). The task used 3, rather than 2, spatial locations, which markedly increased difficulty. There were striking age differences in acquisition. Most of the aged canines did not learn the task, and those that did showed impaired learning when compared with the young canines. The aged canines also showed reduced maximal working memory capacity compared with the young canines. Analysis of the response patterns of individual canines indicated that the deficits were related to the use of ineffective strategies and inflexibility in strategy modification.     

Escape efficiency of diploid and polyploid frogs: A comparison ofOdontophrynus cultripes (2n=22) andO. americanus (4n=44)

The escape efficiency of two closely related species of frogs,Odontophrynus cultripes(2n=22) and the tetraploidO. americanus (4n=44), were compared in a shuttle box and under simulated naturalistic conditions.O. americanus was generally superior toO. cultripes, and females tended to outperform males within both species. The relative inefficiency ofO. cultripes escape behavior was examined in light of the animals' having an elaborate, passive defense mechanism in the form of well-marked venom glands. Escape efficiency was highly variable in both species. Possessing twice the amount of DNA, the tetraploid behavioral variation was paradoxically less than that of the diploid, but compatible with what has been found for morphological characters in other organisms.This research was carried out at the Instituto Butantan with the support of ongoing grants from the Brazilian CNPq, FAPESP, FEDIB, and PNUD while the first author was a visiting professor in the Departamento de Genética Humana, Instituto de Biociências, Universidade de São Paulo, under the auspices of the Programa Multinacional de Genética, Organization of American States.     

Gamma interferon does not enhance clearance of Pseudomonas aeruginosa but does amplify a proinflammatory response in a murine model of postseptic immunosuppression

Patients that have suffered a major injury may sustain a period of immunocompromise and altered Th1/Th2 cytokine balance that can predispose them to opportunistic infections. Pseudomonas aeruginosa is frequently a causative organism for nosocomial infections in critically ill patients and is associated with high mortality. We previously mimicked this clinical scenario by challenging mice with P. aeruginosa 5 days after a cecal ligation and puncture (CLP) procedure. Mice that were subjected to CLP had reduced ability to clear bacteria, significantly lower gamma interferon (IFN-gamma) concentrations in plasma, and significantly elevated levels of interleukin 10 (IL-10) in plasma in response to the Pseudomonas challenge compared to uninjured control mice. We investigated the significance of the alteration in IFN-gamma by administering recombinant IFN-gamma to post-CLP mice at the time of Pseudomonas challenge and by challenging IFN-gamma knockout (IFN-gamma KO) mice with Pseudomonas. Administration of IFN-gamma to post-CLP mice attenuated IL-10 secretion and enhanced IL-12 secretion but did not improve bacterial clearance or survival after Pseudomonas challenge. Furthermore, IFN-gamma KO mice had significantly higher plasma IL-10 concentrations but did not exhibit impaired bacterial clearance or increased mortality following Pseudomonas challenge. These data indicate that systemic administration of IFN-gamma effectively reverses alterations in immune function that are commonly associated with immunosuppression in critically injured mice but does not improve bacterial clearance or survival following Pseudomonas challenge. Further, endogenous IFN-gamma does not appear to contribute significantly to early clearance of Pseudomonas bacteremia, nor does it affect the mortality rate after a lethal Pseudomonas challenge.     

Enchondroma and chondrosarcoma

Enchondroma and chondrosarcoma are two of the most commonly encountered primary bone lesions in the typical radiology practice. The purpose of this article is to review the clinical, radiological, and pathological features that distinguish conventional chondrosarcoma from enchondroma. Chondrosarcoma is almost always associated with pain and tends to present in the axial skeleton of middle aged adults. Enchondroma tends to present in young adults in the appendicular skeleton, particularly the hands, and is often an incidental finding. Although both lesions have characteristic radiographic appearances, difficulty separating these two entities most often occurs when a lesion is seen in the long tubular bones. The judicious use of computed tomography, magnetic resonance imaging, and nuclear medicine in conjunction with appropriate clinical data allows the radiologist to establish the correct diagnosis of benign or malignant medullary chondroid lesion in the majority of cases.     

Langerhans' cell histiocytosis in patients older than 21 years

In this retrospective review of 541 patients with Langerhans' cell histiocytosis, 211 (39%) patients were older than 21 years of age, whereas 330 (61%) were younger than 21 years of age. The adult patients had a mean age of 32 years (range, 21-69 years) with 159 (75%) men and 52 (25%) women, whereas the pediatric patients consisted of 176 (55%) boys and 144 (45%) girls. This male predominance in adults was statistically significant. Three adults had the Hand-Schuller-Christian variant, whereas the remaining adults (208) had eosinophilic granuloma. The rib accounted for 25% of the adult lesions and only 8% of the pediatric lesions. Spine involvement was less common in the adult group (3% versus 10%) and was predominantly thoracic. The adult patients had 40 (77%) diaphyseal lesions, 12 (23%) metaphyseal lesions, and no epiphyseal lesions. The pediatric patients had 75 (54%) diaphyseal, 59 (42%) metaphyseal, and five (4%) epiphyseal lesions. Radiographic evaluation revealed similar margin and matrix patterns in both groups, with a geographic lesion without sclerotic borders being the most common pattern. Langerhans' cell histiocytosis is considered a pediatric disease. However, this study showed a significant number (39%) of patients older than 21 years of age with this condition.     

Effect of combined AT1 receptor and aldosterone receptor antagonism on plasminogen activator inhibitor-1

Aldosterone enhances angiotensin II (Ang II)-induced plasminogen activator inhibitor (PAI)-1 expression in vitro. This study tested the hypothesis that angiotensin II type 1 (AT(1)) and aldosterone receptor antagonism interact to decrease PAI-1 in humans. Effects of candesartan (16 mg/d), spironolactone (25 mg/d), or combined candesartan/spironolactone on mean arterial pressure (MAP), endocrine, and fibrinolytic variables were measured in 18 normotensive subjects [age 33.7 yr (95% confidence interval 29.3, 38.0), body mass index 26.6 (24.7, 28.4) kg/m(2)] in whom the renin-angiotensin-aldosterone system was activated by furosemide (20 mg/d). Candesartan [83.3 mm Hg (78.9, 87.7)], but not spironolactone [89.4 mm Hg (85.4, 93.5)], decreased MAP, compared with baseline [92.2 mm Hg (88.9, 95.5), P < 0.001] and furosemide alone [89.1 mm Hg (85.7, 92.4), P = 0.002]. Coadministration of spironolactone with candesartan did not further decrease MAP. Candesartan dramatically increased Ang II [177.9 pg/ml (113.3, 242.6)], compared with baseline [34.8 pg/ml (29.3, 40.4), P = 0.002] and furosemide alone [40.6 pg/ml (29.7, 51.5), P = 0.003]. Spironolactone increased Ang II [51.5 pg/ml (41.3, 61.7), P = 0.014 vs. baseline, P = 0.004 vs. candesartan]. There was no additive effect of candesartan and spironolactone on Ang II [197.6 pg/ml (134.2, 261.0)]. Aldosterone was lower during candesartan [8.9 ng/dl (7.3, 10.6), P = 0.007] than during furosemide alone [14.1 ng/dl (10.9, 17.3), P = 0.007], spironolactone [18.7 ng/dl (14.5, 22.9), P = 0.002], or combined candesartan/spironolactone [13.9 ng/dl (11.8, 15.9), P = 0.006]. Furosemide increased PAI-1 antigen [27.8 ng/ml (20.6, 35.0), P = 0.002 vs. 19.3 ng/ml (13.4, 25.2) baseline], even in the presence of candesartan [27.2 ng/ml (16.5, 37.8), P = 0.042 vs. baseline] or spironolactone [27.3 ng/ml (17.9, 36.8), P = 0.015 vs. baseline]. However, coadministration of AT(1) and aldosterone receptor antagonists prevented the furosemide-induced increase in PAI-1 [19.2 ng/ml (9.8, 28.6), P = 0.974 vs. baseline, P < 0.05 vs. candesartan, spironolactone or furosemide alone]. This study evidences an interactive effect of endogenous Ang II and aldosterone on PAI-1 production in humans.     

Familial patterns of risk in very late-onset Alzheimer disease

BACKGROUND: The incidence of Alzheimer disease (AD) peaks after 85 years of age. Although genetic factors are implicated in AD with substantially earlier onset, the familial characteristics of high-incidence very late-onset AD (VLOAD, defined here as AD with onset age >/=85 years) remain unknown. METHODS: We collected information pertaining to the cognitive status and demographics of 809 parents and siblings of 144 VLOAD probands, 4235 parents and siblings of 793 earlier-onset AD probands, and 7646 parents and siblings of 1493 nondemented elderly probands. Cumulative risks and 5-year interval-specific hazard rate ratios were calculated for AD in relatives of the 2 AD proband groups and relatives of the nondemented elderly group. RESULTS: The cumulative risk for AD in the relatives of VLOAD probands was significantly different than that in the relatives of earlier-onset AD probands (P<.001), but not in the relatives of nondemented elderly probands. Also, the relatives of earlier-onset AD probands had hazard rate ratios ranging from 19.7 in those aged 50 to 54 years to 1.2 in those aged 90 to 94 years. Rates successively dropped as age intervals increased. CONCLUSIONS: At least through the middle of the ninth decade of life, relatives of VLOAD probands have a lower risk for AD than those of earlier-onset AD probands. In addition, the relatively increased risk of relatives of earlier-onset AD probands is highest at younger ages and diminishes with increasing age. In counseling family members of patients with AD concerned about their own risk, the onset age of the patient and the age of the concerned relative should be considered. Very late-onset AD may be a good target for investigating environmental factors associated with AD.