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  • 1995-1999  (16)
  • 1955-1959
  • Optic neuritis  (4)
  • Analytical Chemistry and Spectroscopy  (3)
  • Altitude acclimatization  (2)
  • Biochemistry and Biotechnology  (2)
  • Canine  (2)
  • Computational Chemistry and Molecular Modeling
  • United States
Material
Years
Year
Keywords
  • 1
    ISSN: 1432-1912
    Keywords: Dispersion ; Refractoriness ; ATP-sensitive potassium channel ; Canine ; Programmed electrical stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The proarrhythmic effects of the ATP-sensitive potassium channel modulators cromakalim (n = 10; 0.01 to 0.3 mg/kg i.v.), glibenclamide (n = 10; 0.3 to 10 mg/kg i.v.) or volume equivalents of vehicle (n = 10) were evaluated in post-infarcted anaesthetised dogs. Dogs were anaesthetised, subjected to an anterior-apical myocardial infarction, and allowed to recover. At 7.4 ± 0.7 days post infarction, animals were anaesthetised again, electrophysiologic measurements (effective refractory periods, QT-intervals and ventricular fibrillation thresholds) were taken, and animals were tested for arrhythmias using a programmed electrical stimulation protocol. Only animals that did not have programmed electrical stimulation-inducible arrhythmias were used. Ventricular fibrillation thresholds were determined twice, once before the first dose then after the last dose of drug. At the end of the experiment, animals were subjected to ligation of the left circumflex coronary artery and survival was measured over the next two hours. Cromakalim significantly increased heart rate and decreased blood pressure. Although cromakalim significantly reduced effective refractory periods, it neither increased electrical dispersion, as determined by the standard deviation or coefficient of variance of the effective refractory period, nor did it enhance inducibility (0 out of 10 in both vehicle and cromakalim treated animals), change ventricular fibrillation thresholds, or reduce sudden death survival relative to vehicle. Glibenclamide did not increase electrical dispersion, but slightly increased the incidence of programmed electrical stimulation-induced arrhythmias (3 out of 10), and lowered ventricular fibrillation thresholds values. However, these changes were not statistically significant. Glibenclamide did not significantly affect survival relative to vehicle. Infarct sizes of the left ventricle were not statistically different among groups. In conclusion, cromakalim and glibenclamide did not affect dispersion of refractoriness. Glibenclamide did demonstrate a propensity towards proarrhythmic activity. However, the doses needed to observe proarrhythmic activity with glibenclamide were significantly higher than those needed for clinical treatment of hyperglycemia.
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  • 2
    ISSN: 1432-1912
    Keywords: Key words Dispersion ; Refractoriness ; ATP-sensitive potassium channel ; Canine ; Programmed electrical stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The proarrhythmic effects of the ATP-sensitive potassium channel modulators cromakalim (n=10; 0.01 to 0.3 mg/kg i.v.), glibenclamide (n=10; 0.3 to 10 mg/kg i.v.) or volume equivalents of vehicle (n=10) were evaluated in post-infarcted anaesthetised dogs. Dogs were anaesthetised, subjected to an anterior-apical myocardial infarction, and allowed to recover. At 7.4±0.7 days post infarction, animals were anaesthetised again, electrophysiologic measurements (effective refractory periods, QT-intervals and ventricular fibrillation thresholds) were taken, and animals were tested for arrhythmias using a programmed electrical stimulation protocol. Only animals that did not have programmed electrical stimulation-inducible arrhythmias were used. Ventricular fibrillation thresholds were determined twice, once before the first dose then after the last dose of drug. At the end of the experiment, animals were subjected to ligation of the left circumflex coronary artery and survival was measured over the next two hours. Cromakalim significantly increased heart rate and decreased blood pressure. Although cromakalim significantly reduced effective refractory periods, it neither increased electrical dispersion, as determined by the standard deviation or coefficient of variance of the effective refractory period, nor did it enhance inducibility (0 out of 10 in both vehicle and cromakalim treated animals), change ventricular fibrillation thresholds, or reduce sudden death survival relative to vehicle. Glibenclamide did not increase electrical dispersion, but slightly increased the incidence of programmed electrical stimulation-induced arrhythmias (3 out of 10), and lowered ventricular fibrillation thresholds values. However, these changes were not statistically significant. Glibenclamide did not significantly affect survival relative to vehicle. Infarct sizes of the left ventricle were not statistically different among groups. In conclusion, cromakalim and glibenclamide did not affect dispersion of refractoriness. Glibenclamide did demonstrate a propensity towards proarrhythmic activity. However, the doses needed to observe proarrhythmic activity with glibenclamide were significantly higher than those needed for clinical treatment of hyperglycemia.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1920
    Keywords: Key words Magnetic resonance imaging ; Optic neuritis ; Multiple sclerosis ; Visual evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI of the optic nerves was obtained in 13 patients with acute optic neuritis and 13 with a previous optic neuritis (ON), assessed by clinical features, visual fields and visual evoked potentials. Results of the conventional short tau inversion recovery (STIR) sequence obtained with a short echo time (STE-STIR; 22 ms) were compared with those of a long echo time (LTE-STIR: 80 ms) sequence. The conventional STE-STIR sequence revealed lesions in the optic nerves in 78.5 % of acute and 58.8 % of previous ON. The LTE-STIR sequence showed abnormalities in 92.8 % of acutely symptomatic nerves and 94.1 % of nerves with previous ON. The optic nerve lesions appeared significantly longer with the LTE-STIR sequence than with the conventional STE-STIR sequences, in both acute and previous ON.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Optic neuritis ; Multiple sclerosis ; Visual evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI of the optic nerves was obtained in 13 patients with acute optic neuritis and 13 with a previous optic neuritis (ON), assessed by clinical features, visual fields and visual evoked potentials. Results of the conventional short tau inversion recovery (STIR) sequence obtained with a short echo time (STE-STIR; 22 ms) were compared with those of a long echo time (LTE-STIR: 80 ms) sequence. The conventional STE-STIR sequence revealed lesions in the optic nerves in 78.5% of acute and 58.8% of previous ON. The LTE-STIR sequence showed abnormalities in 92.8% of acutely symptomatic nerves and 94.1% of nerves with previous ON. The optic nerve lesions appeared significantly longer with the LTE-STIR sequence than with the conventional STE-STIR sequences, in both acute and previous ON.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 73 (1996), S. 202-209 
    ISSN: 1439-6327
    Keywords: Peripheral chemoreceptors ; Hypoxic ventilatory response ; Altitude acclimatization ; High altitude
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Hypoxic ventilatory response (HVR) was examined before and after acclimatization to high altitude. Transient hyperoxic switches according to Dejours's technique were used to examine the contribution of HVR to the hyperpnoea of increasing exercise intensities. Ten mountaineers were exposed to hypoxia (oxygen fraction in inspired gas,F 1O2 = 0.11, 79 mmHg) before the expedition and after return from altitude (56 days, 30 days at 4900 m or higher). After 25-min breathing hypoxic gas, the subjects performed a maximal cycle ergometer test (increments 50 W per 5 min). Respired gases and ventilation $$(\dot V_E )$$ were analysed breath-by-breath, partial pressure of oxygen (PO2) and oxygen saturation (SO2) were measured in capillary blood. The HVR was tested by switching two breaths to anF 1O2 of 1.0. The nadir of $$\dot V_E $$ after the switch was measured (decrease in ventilation, D $$\dot V_E $$ ). The HVR was expressed as the D $$\dot V_E $$ at a PO2 of 40 mmHg (D $$\dot V_{E40} $$ ) and the D $$\dot V_E $$ versus decrease ofSO2 (D $$\dot V_E $$ /[100 −SO2]). The HVR estimated by D $$\dot V_{E40} $$ increased from 19.9 to 28.01 · min−1 (median,P = 0.013). The HVR expressed as D $$\dot V_E $$ /(100 −SO2) at rest was no different before and after acclimatization (0.89 and 0.86 l · min−1 · %−1, respectively) and during exercise it did not change before the expedition (0.831 · min−1 %−1). However, D $$\dot V_E $$ /(100 −SO2) increased significantly with exercise intensity after the expedition (1.61 l · min−1 · %−1 at 200 W). The changes of D $$\dot V_E $$ versusSO2 as well as of D $$\dot V_E $$ versus $$\dot V_E $$ were steeper after the expedition than before. In summary, after return from 30 day at high altitude, an increased HVR was observed. The augmentation of HVR was evident at higher exercise intensities and we suggest that this reflects a change in sensitivity of the peripheral chemoreflex loop.
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  • 6
    ISSN: 1439-6327
    Keywords: Hypoxia ; Exercise ; Rebreathing Alveolar-arterial difference ; Altitude acclimatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Studies were made of pulmonary diffusion capacity and oxygen transport before and after an expedition to altitudes at and above 4900 m. Maximum power (P max) and maximal oxygen uptake (VO 2max) were measured in 11 mountaineers in an incremental cycle ergometer test (25W · min−1) before and after return from basecamp (30 days at 4900 m or higher). In a second test, cardiac output (Q c) and lung diffusion capacity of carbon monoxide (D L,CO) were measured by acetylene and CO rebreathing at rest and during exercise at low, medium and submaximal intensities. After acclimatization, VO2max and P max decreased by 5.1% [from 61.0 (SD 6.2) to 57.9 (SD 10.2) ml·kg−1, n.s.] and 9.9% [from 5.13 (SD 0.66) to 4.62 (SD 0.42) W·kg−1, n.s.], respectively. The maximal cardiac index and DL,co decreased significantly by 15.6% [14.1 (SD 1.41) 1·min−1 · m−2 to 11.9 (SD 1.44)1·min−1 m−2, P〈0.05] and 14.3% [85.9 (SD 4.36)ml·mmHg−1 min−t to 73.6 (SD 15.2) ml · mmHg−1 -min−1, P〈0.05], respectively. The expedition to high altitude led to a decrease in maximal Q c, oxygen uptake and DL,CO. A decrease in muscle mass and capillarity may have been responsible for the decrease in maximal Qc which may have resulted in a decrease of D L,CO and an increase in alveolar-arterial oxygen difference. The decrease in D L,CO especially at lower exercise intensities after the expedition may have been due to a ventilation-perfusion mismatch and changes in blood capacitance. At higher exercise intensities diffusion limitation due to reduced pulmonary capillary contact time may also have occurred.
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  • 7
    ISSN: 1573-7225
    Keywords: Colon cancer ; diet ; family history ; United States ; women
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: The purpose was to investigate whether dietary associations with risk of colon cancer in women differ by family history of the disease. Methods: Data were analyzed from a prospective cohort study of 35,216 Iowa (United States) women aged 55 to 69 years at baseline. Through 31 December 1995, 241 colon cancers were identified through record linkage with the State Health Registry. The cohort was stratified on family history of colon cancer in first-degree relatives; nutrient intakes were divided into tertiles. Results: Analyses using Cox regression revealed that the association of most dietary components with colon cancer incidence were similar for individuals with and without a family history. However, total calcium intake was associated inversely with colon cancer among women with a negative family history (relative risk [RR]=0.50 for upper cf lower tertile, P 〈 0.001), but was unrelated to incidence for women with a positive family history (RR=1.1 for upper cf lower tertile, P=0.69). Similarly, total vitamin E intake was associated with lower risk among women with a negative family history (RR=0.67 for upper cf lower tertile, P=0.04), but not among women with a positive family history (RR=0.87 for upper cf lower tertile, P=0.67). High intakes of fiber, fruits, and vegetables were each weakly inversely associated with risk among family-history negative women, but not among family-history positive women. Conclusions: These data, if corroborated, suggest that dietary factors typically associated with lower risk may be less effective risk-reduction interventions against colon cancer for individuals with a family history of colon cancer.
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  • 8
    ISSN: 1573-7225
    Keywords: Breast cancer ; body mass index ; females ; United States ; weight gain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: We examined whether associations of adult weight gain with the risk of postmenopausal breast cancer vary by stature, waist-hip ratio (WHR), and early adult size in a cohort of 37,105 Iowa (United States) women. Both low body mass index (kg/m2) (BMI) at age 18 and high subsequent weight-gain were associated independently with increased risk of incident postmenopausal breast cancer. After stratifying on BMI at age 18, high weight gain was associated with increased risk irrespective of whether early BMI was low (relative risk [RR]=1.92, 95 percent confidence interval [CI]=1.45–2.53) or high (RR=1.59, Ci=1.19–2.12). Women with lower BMI at 18 were at a higher risk at all levels of weight change, but having low BMI at age 18 and low subsequent weight gain conferred no significantly excess risk over those with high BMI at 18 and low gain. An inconsistent increase in risk was associated with taller stature; there was no additional risk associated with high WHR. Part of the observed risk from lower early size may reflect greater weight gain by lighter women. Limiting adult weight gain thus may be a feasible method to avoid increasing an individual's risk of breast cancer. Reasons for different effects of early cf late weight gain are not established, but benefits of a greater size at age 18 are likely to be offset by increased risks of other weight-related diseases at older ages.
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  • 9
    ISSN: 1590-3478
    Keywords: MRI ; Optic neuritis ; Multiple sclerosis ; VEP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario Si descrivono i risultati ottenuti con indagini di Risonanza Magnetica (RM) dei nervi ottici (eseguite all'esordio e 12 mesi dopo) in 20 pazienti affetti da Neurite Ottica (NO) acuta, valutata in funzione della sintomatologia clinica e delle alterazioni campimetriche e del potenziale evocato visivo. Sono state analizzate le immagini RM in Short Tau Inversion Recovery (STIR) mettendo a confronto i rilievi ottenuti con sequenza Short Time Echo (STE-STIR: 22 msec) rispetto a quelli ottenuti con Long Time Echo (LTE-STIR: 20 msec). Mentre con la convenzionale STE-STIR è stato possibile rilevare lesioni a carico dei nervi ottici nel 57.2% delle Neuriti Acute e nel 42.9% delle Neuriti Pregresse, la metodica LTE-STIR è risultata diagnostica nel 95.2% delle Neuriti Acute e nel 85% delle Neuriti Pregresse. Sia nelle NO acute che nelle pregresse, la lunghezza delle lesioni a carico dei nervi ottici sono risultate significativamente maggiori rispetto a quelle ottenute con la convenzionale metodica STE-STIR.
    Notes: Abstract Magnetic resonance images of optic nerves were obtained in 20 patients with acute optic neuritis (ON), and assessed by means of clinical, visual field and visual evoked potential evaluations; the imaging was repeated 1 year later. The results of the conventional Short Tau Inversion Recovery (STIR) sequence obtained using short time echo (STE-STIR: 22 msec) were compared with those of the long time echo sequence (LTE-STIR: 80 msec). The conventional STE-STIR sequence revealed lesions in 57.2% cases of acute ON and in 42.9% of the optic nerves affected by previous ON: the LTE-STIR sequence was diagnostic in 95.2% of acute ON cases and in 85% of patients with previous ON. The calculated length of the optic nerve lesions was significantly longer in the images obtained using the LTE-STIR sequence than in those obtained using conventional STE-STIR sequences.
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  • 10
    ISSN: 1590-3478
    Keywords: Visual evoked potentials ; VEP ; Optic neuritis ; Multiple sclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario I 20 pazienti affetti da Neurite Ottica (NO), descritti nel precedente lavoro [23] sono stati sottoposti a registrazioni seriali multicanali dei Potenziali Evocati Visivi (PEV), per un periodo di 2 anni dall'esordio della NO. I PEV potevano correlare con le lesioni evidenziate con la Risonanza Magnetica, con le alterazioni campimetriche e con altri reperti clinici. Basandoci sulla loro distribuzione in mappa, i PEV sono stati classificati come realmente “ritardati” e “pseudo-ritardati”. PEV realmente “ritardati” potevano essere registrati all'esordio, o precocemente dopo l'episodio di NO, e la presenza del “ritardo” stava ad indicare un recupero della funzione visiva e, quindi, una prognosi fausta. Gli “pseudo-ritardi” indicavano un'alterazione del campo visivo a prognosi non favorevole per un recupero della funzione visiva, a meno che entro i primi 3 mesi dalla NO si fosse verificata una ricomparsa di componenti normali o “ritardate”. Gli “pseudo-ritardi” erano rilievi caratteristici nei pazienti con lesioni maggiormente lunghe alle immagini LTE-STIR MRI [23]. Nessuna correlazione è stata trovata tra latenza dei PEV e lunghezza delle placche. I nostri rilievi sono in disaccordo con precedenti teorie relative ai tempi di instaurazione-recupero delle alterazioni di conduzione nella NO e nella Sclerosi Multipla.
    Notes: Abstract Twenty patients with optic neuritis (ON) described in the previous study [23] underwent serial VEP recordings (using multiple electrode arrays) for two years. The VEPs could be correlated with the lesions revealed by MRI, Visual Field tests and other clinical findings. On the basis of their scalp distribution, they were classified as “really delayed” VEPs and “pseudo-delayed” VEPs. Real delays could be recorded at the onset of ON or shortly afterwards, and their appearance indicated the recovery of visual function and a good prognosis. Pseudo-delays indicated an alteration in the visual field and, unless a breakthrough of normal or delayed components appeared in the first three months, following acute ON, indicate a poor prognosis for the recovery of visual function. The pseudo-delayed VEPs were mainly observed in patients with longer lesions revealed by means of LTE-STIR MRI [23]; there was no correlation between VEP latency and the length of plaques. Our findings contradict previous theories on the timing of conduction alterations in ON and multiple sclerosis.
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