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Biomedical subjects

S E Anderson

Publications and source records attributed to S E Anderson.

At least 19 recordsLinked to original sources
PubMed2007

Anesthesia suppresses nonsynchronous responses to repetitive broadband stimuli.

Although many aspects of sensory processing are qualitatively similar in awake and anesthetized subjects, important state-dependent differences are known to exist. To investigate the effects of anesthesia on temporal processing in rat auditory cortex, multi-unit neural responses to trains of broadband clicks were recorded prior to, 15 min following, and 5 h following the administration of a ketamine-based anesthetic. While responses to clicks in isolation were relatively stable between states, responses to subsequent clicks exhibited increases in latency, peak latency, response duration, and post-onset suppression under anesthesia. Ketamine anesthetic reduced the maximum rate at which multi-unit clusters entrained to repeated clicks. No multi-unit clusters entrained to stimulus presentation rates greater than 33 Hz under anesthesia, compared with 85% and 81% in the pre- and post-anesthetic condition, respectively. Anesthesia also induced oscillatory activity that was not present in awake subjects. Finally, ketamine anesthesia abolished all tonic excitatory and suppressive nonsynchronous responses to click trains. The results of this study suggest that ketamine-based anesthesia significantly alters neural coding of broadband click trains in auditory cortex.

Acoustic Stimulation↗
PubMed2006

Physiology and pathophysiology of Na+/H+ exchange and Na+ -K+ -2Cl- cotransport in the heart, brain, and blood.

Maintenance of a stable cell volume and intracellular pH is critical for normal cell function. Arguably, two of the most important ion transporters involved in these processes are the Na+/H+ exchanger isoform 1 (NHE1) and Na+ -K+ -2Cl- cotransporter isoform 1 (NKCC1). Both NHE1 and NKCC1 are stimulated by cell shrinkage and by numerous other stimuli, including a wide range of hormones and growth factors, and for NHE1, intracellular acidification. Both transporters can be important regulators of cell volume, yet their activity also, directly or indirectly, affects the intracellular concentrations of Na+, Ca2+, Cl-, K+, and H+. Conversely, when either transporter responds to a stimulus other than cell shrinkage and when the driving force is directed to promote Na+ entry, one consequence may be cell swelling. Thus stimulation of NHE1 and/or NKCC1 by a deviation from homeostasis of a given parameter may regulate that parameter at the expense of compromising others, a coupling that may contribute to irreversible cell damage in a number of pathophysiological conditions. This review addresses the roles of NHE1 and NKCC1 in the cellular responses to physiological and pathophysiological stress. The aim is to provide a comprehensive overview of the mechanisms and consequences of stress-induced stimulation of these transporters with focus on the heart, brain, and blood. The physiological stressors reviewed are metabolic/exercise stress, osmotic stress, and mechanical stress, conditions in which NHE1 and NKCC1 play important physiological roles. With respect to pathophysiology, the focus is on ischemia and severe hypoxia where the roles of NHE1 and NKCC1 have been widely studied yet remain controversial and incompletely elucidated.

Animals↗
PubMed2006

Response to broadband repetitive stimuli in auditory cortex of the unanesthetized rat.

This study examines the ability of multi-unit clusters (MUCs) in layer IV/V of primary auditory cortex of the awake rat to respond to a series of broadband click trains. The data from 113 multi-unit clusters were analyzed for synchronous and nonsynchronized responses using several methods. Synchronous responses were measured using window analysis, circular statistics and spectral analysis. Nonsynchronous responses were measured during different time intervals during the click train (first 50 ms, 50-450 ms, and the entire click train). The results demonstrate that multi-unit clusters are capable of synchronizing to clicks at rates up to 166 Hz. The mean synchronization boundary (limiting rate) for the group was found to be 72 Hz. Mean peak response rate, mean response duration, and mean time-to-peak response decreased as the stimulus presentation rate (SPR) increased, resulting in a temporal sharpening of the population response. For fast SPRs (>50 Hz), 50% of MUCs exhibited nonsynchronous responses in which the firing rate increased with SPR, although this activity was most prevalent during the first 50 ms of the response. Sustained increases in firing rate with SPR were seen in 8% of the MUCs, while another 38% of MUCs exhibited sustained decreases during the click train.

Acoustic Stimulation↗
PubMed2005

Estimation of pelvic tilt on anteroposterior X-rays--a comparison of six parameters.

OBJECTIVE: To compare six different parameters described in literature for estimation of pelvic tilt on an anteroposterior pelvic radiograph and to create a simple nomogram for tilt correction of prosthetic cup version in total hip arthroplasty. DESIGN: Simultaneous anteroposterior and lateral pelvic radiographs are taken routinely in our institution and were analyzed prospectively. The different parameters (including three distances and three ratios) were measured and compared to the actual pelvic tilt on the lateral radiograph using simple linear regression analysis. PATIENTS: One hundred and four consecutive patients (41 men, 63 women with a mean age of 31.7 years, SD 9.2 years, range 15.7-59.1 years) were studied. RESULTS: The strongest correlation between pelvic tilt and one of the six parameters for both men and women was the distance between the upper border of the symphysis and the sacrococcygeal joint. The correlation coefficient was 0.68 for men (P<0.001) and 0.61 for women (P<0.001). Based on this linear correlation, a nomogram was created that enables fast, tilt-corrected cup version measurements in clinical routine use. CONCLUSION: This simple method for correcting variations in pelvic tilt on plain radiographs can potentially improve the radiologist's ability to diagnose and interpret malformations of the acetabulum (particularly acetabular retroversion and excessive acetabular overcoverage) and post-operative orientation of the prosthetic acetabulum.

Adolescent↗
PubMed2005

Coil embolization of an infected superior gluteal artery pseudoaneurysm caused by methicillin-resistant Staphylococcus aureus.

We describe the successful selective coil embolization of an infected superior gluteal pseudoaneurysm secondary to methicillin-resistant Staphylococcus aureus (MRSA) in a 36-year old women. The patient presented with a long history of drug abuse and perisacral abscesses due to chronic sacroilitis. The chosen strategy provides a safe and successful management of infected false gluteal artery aneurysm.

Abscess↗
PubMed2005

Child temperament does not predict adolescent body composition in girls.

OBJECTIVES: Our previous cross-sectional analysis of MIT Growth and Development (MIT) Study girls showed that activity temperament, as assessed by a nine-item temperament questionnaire, was related to body composition and nonresting energy expenditure (NREE). In girls with lower levels of physical activity, having a high activity temperament was associated with a higher NREE. Percentage body fat was lower in girls with high vs low activity temperament. Based on these results, we hypothesized that, especially in girls with declining levels of physical activity over adolescence, high activity temperament in childhood would be protective against increased adiposity during adolescence. We tested this hypothesis with longitudinal data from the MIT study. DESIGN, SETTING, AND PARTICIPANTS: A total of 196 nonobese premenarcheal girls 8-12 y old were enrolled between 1990 and 1993. Girls were followed until 4 y postmenarche; average duration of follow-up was 7 y. MEASURES: Activity temperament was assessed at baseline by the girls' mothers with questions modified from those developed by Thomas and Chess that tapped predilection for movement. Temperament, the stylistic component of behavior, is considered relatively stable within an individual. Body composition was assessed by total body water at baseline and study completion (4 y postmenarche), and by bioelectrical impedance (BIA) annually. Physical activity was assessed annually by questionnaire, and by activity diary at baseline only. RESULTS: Child activity temperament was not associated with percentage body fat at 4 y postmenarche in multivariate regression models controlling for baseline percentage body fat, physical activity, parental obesity status, age at menarche, age at baseline, and race-ethnicity. Body composition of girls with low and high activity temperaments who reported declining levels of physical activity over adolescence was not statistically significantly different at study completion. In longitudinal models of percentage body fat by BIA, high activity temperament was not associated with lower adiposity. CONCLUSION: Although high activity temperament was associated cross-sectionally with lower percentage body fat and higher NREE, we did not find evidence to support our hypothesis that high child activity temperament would be protective for increased adiposity prospectively in our cohort of girls followed over the adolescent period.

Aging↗
PubMed2004

Harris lines of the tibia across centuries: a comparison of two populations, medieval and contemporary in Central Europe.

OBJECTIVE: To determine the incidence of Harris lines in two medieval populations which inhabited the Canton of Berne, in Central Switzerland, and to compare the results with those of a contemporary population living in the same geographical area. A simplified method is described for measuring the age of the individual at the time of formation of Harris lines, with possible future applications. DESIGN AND PATIENTS: Radiographs of 112 well-preserved tibiae of skeletons of two medieval populations from the eighth to fifteenth centuries were reviewed for the incidence of Harris lines. The results were compared with those of 138 current patients living in the same geographic location in Central Switzerland. Age and gender of the medieval individual were determined using known anthropological methods. Age of bone at the time of formation of Harris lines was estimated according to the method of Maat. RESULTS: Harris lines were found in 88 of 112 (80%) of the examined medieval skeletons and in 28 of 138 (20%) of the living individuals. Higher incidences of Harris lines were found at the age of 2 years and at ages between 8 and 12 years in both populations. No gender difference was found regarding the incidence of Harris lines. In both populations the occurrence of Harris lines was associated with certain diseases such as degenerative bone disease, trauma, osteoporosis, rheumatoid arthritis, peripheral vascular diseases, rickets and bony deformities. CONCLUSION: A high incidence of Harris lines was found in the medieval population, perhaps reflecting difficult living and hygienic conditions, but also the poor care and neglect of the children population. Measuring the age of the individual at the time of formation of Harris lines is simple and may have future clinical applications in the paediatric population for medico-legal purposes. The application of Harris lines as a marker in follow-up of osteoporosis may need further evaluation.

Adolescent↗
PubMed2004

Adductor insertion avulsion syndrome, "thigh splints": relevance of radiological follow-up.

We present a case of chronic osteomyelitis in a 13-year-old girl which was originally diagnosed as adductor insertion avulsion syndrome ("thigh splints") on the basis of the clinical presentation, patient history, initial radiographs and MRI examination. However, at follow-up with persistent pain and altered radiographic and MRI appearances, surgical biopsy was indicated. Histopathological findings confirmed a bone abscess. This case underlines the necessity of clinical follow-up and imaging in certain patients with apparent thigh splints.

Adolescent↗
PubMed2004

Stewart-Treves syndrome: MR imaging of a postmastectomy upper-limb chronic lymphedema with angiosarcoma.

The rare occurrence of angiosarcoma in postmastectomy upper-limb lymphedema with magnetic resonance (MR) imaging is discussed. Unfamiliarity with this aggressive vascular tumor and its harmless appearance often leads to delayed diagnosis. Angiosarcoma complicating chronic lymphedema may be low in signal intensity on T2-weighting and short tau inversion recovery (STIR) imaging reflecting the densely cellular, fibrous stroma, and sparsely vascularized tumor histology. Additional administration of intravenous contrast medium revealed significant enhancement of the tumorous lesions. Awareness of angiosarcoma and its MR imaging appearance in patients with chronic lymphedema may be a key to early diagnosis or allow at least inclusion in the differential diagnosis.

Aged, 80 and over↗
PubMed2004

Shoe rim and shoe buckle pseudotumor of the ankle in elite and professional figure skaters and snowboarders: MR imaging findings.

OBJECTIVE: To review MR imaging of figure skaters and snowboarders presenting with painful soft-tissue swelling of the lateral supramalleolar region with a clinical provisional diagnosis of soft-tissue tumor. DESIGN AND PATIENTS: MR imaging was prospectively reviewed by two sub-specialized musculoskeletal radiologists. The findings were correlated with a second clinical review and examination of the shoe wear. The patients were four female athletes undergoing heavy training regimes, ranging in age between 16 and 25 years. Two patients were elite figure skaters, and two were professional snowboarders. Three patients had unilateral masses with pain, and one patient presented with bilateral clinical findings. RESULTS: MR imaging showed subcutaneous, focal soft-tissue masses of the supramalleolar region in five ankles at the same level above the ankle joint. MR imaging prompted a second clinical review and correlation with the shoe wear. The MR imaging findings correlated to the level of the shoe rim or shoe buckle in all patients, confirming the suspected MR imaging diagnosis of an impingement syndrome. All four sportswomen were training excessively, ignoring safety advice regarding training duration, timing of breaks, and shoe wear rotation. CONCLUSION: Ice skaters and snowboarders may present with persistent and disabling pain. On MR imaging, this corresponds to a focal soft-tissue abnormality, which may be due to subcutaneous fat impingement between the fibula and the shoe rim or shoe buckle.

Adolescent↗
PubMed2004

Postpartum osteoporosis associated with proximal tibial stress fracture.

A 33-year-old woman presented with acute nonspecific knee pain, 6 months postpartum. MR imaging, computed tomography and radiography were performed and a proximal tibia plateau insufficiency fracture was detected. Bone densitometry demonstrated mild postpartum osteoporosis. To our knowledge these findings have not been described in this location and in this clinical setting. The etiology of the atraumatic fracture of the tibia is presumed to be due to a low bone mineral density. The bone loss was probably due to pregnancy, lactation and postpartum hormonal changes. There were no other inciting causes and the patient was normocalcemic. We discuss the presence of a postpartum stress fracture in a hitherto undescribed site in a patient who had lactated following an uncomplicated pregnancy and had no other identifiable cause for a stress fracture.

Absorptiometry, Photon↗
PubMed2004

Relationship between temperament, nonresting energy expenditure, body composition, and physical activity in girls.

OBJECTIVES: To assess the extent that predilection for movement, as measured by a temperament questionnaire (activity temperament), contributes to nonresting energy expenditure and body composition in girls. DESIGN, SETTING, AND PARTICIPANTS: Baseline data for 196 premenarcheal non-obese girls aged 8-12 y were obtained from a longitudinal study of growth and development. The association of activity temperament with nonresting energy expenditure in girls with low and high levels of physical activity was evaluated, as was the association of activity temperament with body composition. MEASURES: Maternal reports of child activity temperament were obtained by questionnaire. Nonresting energy expenditure was calculated as total energy expenditure (measured by doubly labeled water) minus resting energy expenditure (obtained by indirect calorimetry). Body composition was estimated by total body water. Questionnaires and activity diaries were used to assess physical activity and sedentary behavior. RESULTS: Higher activity temperament was associated with higher nonresting energy expenditure after multivariate control for weight, vigorous activity, walking and light activity, and television viewing, although activity temperament did not account for a large percentage of the variability in nonresting energy expenditure (partial squared correlation coefficient=0.03). In girls with physical activity levels below the median, high activity temperament was associated with a mean+/-s.d., nonresting energy expenditure of 310+/-138 kJ (74+/-33 kcal) above that of girls with a low activity temperament. Girls with a high activity temperament had less body fat than did girls with a low activity temperament (21.6 vs 24.5%, a difference of 2.9 percentage points; 95% confidence interval, 1.3-4.4 percentage points). CONCLUSION: Predilection for movement, as measured by a temperament questionnaire, contributes to nonresting energy expenditure and may be useful in capturing an aspect of energy expenditure in population studies. The cross-sectional observation that girls with a high activity temperament were leaner than girls with a low activity temperament suggests that a constitutional predilection for movement may play a role in the development of obesity.

Anthropometry↗
PubMed2003

Imaging of chronic recurrent multifocal osteomyelitis of childhood first presenting with isolated primary spinal involvement.

OBJECTIVE: Initial presentation with primary spinal involvement in chronic recurrent multifocal osteomyelitis of childhood (CRMO) is rare. Our objective was to review the imaging appearances of three patients who had CRMO who initially presented with isolated primary spinal involvement. DESIGN AND PATIENTS: The imaging, clinical, laboratory and histology findings of the three patients were retrospectively reviewed. Imaging included seven spinal MR imaging scans, one computed tomography scan, nine bone scans, two tomograms and 16 radiographs. These were reviewed by two musculoskeletal radiologists and a consensus view is reported. All three patients presented with atraumatic spinal pain and had extensive bone spinal pathology. The patients were aged 11, 13 and 12 years. There were two females and one male. RESULTS AND CONCLUSIONS: The initial patient had thoracic T6 and T8 vertebra plana. Bone scan showed additional vertebral body involvement. Follow-up was available over a 3 year period. The second patient had partial collapse of T9 and, 2 years later, of C6. Subsequently extensive multifocal disease ensued and follow-up was available over 8 years. The third patient initially had L3 inferior partial collapse and 1 year later T8 involvement with multifocal disease. Follow-up was available over 3 years. The imaging findings of the three patients include partial and complete vertebra plana with a subchondral line adjacent to endplates associated with bone marrow MR signal alterations. Awareness of the imaging appearances may help the radiologist to include this entity in the differential diagnosis in children who present with spinal pathology and no history of trauma. Histopathological examination excludes tumor and infection but with typical imaging findings may not always be necessary.

Adolescent↗
PubMed2003

Age-related differences in Na+-dependent Ca2+ accumulation in rabbit hearts exposed to hypoxia and acidification.

In this study, we test the hypothesis that in newborn hearts (as in adults) hypoxia and acidification stimulate increased Na(+) uptake, in part via pH-regulatory Na(+)/H(+) exchange. Resulting increases in intracellular Na(+) (Na(i)) alter the force driving the Na(+)/Ca(2+) exchanger and lead to increased intracellular Ca(2+). NMR spectroscopy measured Na(i) and cytosolic Ca(2+) concentration ([Ca(2+)](i)) and pH (pH(i)) in isolated, Langendorff-perfused 4- to 7-day-old rabbit hearts. After Na(+)/K(+) ATPase inhibition, hypoxic hearts gained Na(+), whereas normoxic controls did not [19 +/- 3.4 to 139 +/- 14.6 vs. 22 +/- 1.9 to 22 +/- 2.5 (SE) meq/kg dry wt, respectively]. In normoxic hearts acidified using the NH(4)Cl prepulse, pH(i) fell rapidly and recovered, whereas Na(i) rose from 31 +/- 18.2 to 117.7 +/- 20.5 meq/kg dry wt. Both protocols caused increases in [Ca](i); however, [Ca](i) increased less in newborn hearts than in adults (P < 0.05). Increases in Na(i) and [Ca](i) were inhibited by the Na(+)/H(+) exchange inhibitor methylisobutylamiloride (MIA, 40 microM; P < 0.05), as well as by increasing perfusate osmolarity (+30 mosM) immediately before and during hypoxia (P < 0.05). The data support the hypothesis that in newborn hearts, like adults, increases in Na(i) and [Ca](i) during hypoxia and after normoxic acidification are in large part the result of increased uptake via Na(+)/H(+) and Na(+)/Ca(2+) exchange, respectively. However, for similar hypoxia and acidification protocols, this increase in [Ca](i) is less in newborn than adult hearts.

Acids↗
PubMed2003

Imaging features of pseudoaneurysms of the hand in children and adults.

OBJECTIVE: Our objective was to review the imaging features of pseudoaneurysms of the hand in 25 patients. The patients presented with a mass, peripheral paresthesia, or ischemia. Pseudoaneurysm of the hand is a rare and often clinically unsuspected diagnosis. Correct diagnosis is important because there are risks for distal embolic disease with ischemia or gangrene of the fingers, ulnar or digital nerve dysfunction, rupture, or bone erosion and joint destruction. Scant reports appear in the world literature, and this report is the first review, to our knowledge, of the imaging features. The cause may be a history of a single direct trauma or chronic trauma, as seen in patients with hypothenar or thenar hammer syndrome. CONCLUSION: Awareness of the specific imaging appearances of pseudoaneurysms of the hand and their complications may improve the accuracy of radiologic diagnosis, advance the preoperative workup, and prevent possible clinical complications such as digital gangrene, nerve dysfunction, and aneurysm rupture.

Adolescent↗
PubMed2003

MR imaging of calcification of the lateral collateral ligament of the knee: a rare abnormality and a cause of lateral knee pain.

OBJECTIVE: Our objective was to describe the radiologic appearances of calcification of the lateral collateral ligament (LCL) of the knee in four patients who presented with acute atraumatic lateral knee pain. This rare abnormality has not, to our knowledge, been previously shown on MR imaging. CONCLUSION: Calcification of the LCL of the knee is a rare cause of lateral knee pain and is thought to reflect underlying hydroxyapatite deposition. On MR imaging, calcification of the LCL may be associated with an aggressive appearance that can be mistaken for other knee abnormalities.

Adult↗