Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate the effects of long-term reductions in perfusion pressure on blood flow responses to increased functional demand, 5 patients (aged 12 to 26 years) without normal aortic to subclavian artery blood flow to 1 arm as a result of surgery to treat congenital heart disease were studied. Five age- and sex-matched healthy (control) subjects were also studied. In the patients, forearm blood flow was not different in the surgical and normal arms at rest (3.6 +/- 0.6 vs 4.0 +/- 0.7 ml/min/100 ml, respectively, mean +/- standard error, difference not significant) despite lower systolic blood pressure in the surgical arm (87 +/- 2 vs 115 +/- 2 mm Hg, p less than 0.05). The increases in heart rate, systolic blood pressure, forearm electromyographic activity (index of muscle fatigue) and postexercise forearm blood flow (index of muscle oxygen deficit) were not different in response to 2.5 minutes of submaximal rhythmic handgrip exercise (50% of maximal force) performed with the surgical versus the normal arms. Peak forearm blood flow elicited by combined ischemia and maximal isometric handgrip exercise was not significantly different in surgical and normal arms in the group as a whole (39 +/- 4 vs 43 +/- 3 ml/min/100 ml, difference not significant), although some bilateral deficit (20 to 38%) was observed in 2 patients. No bilateral differences were observed in the control subjects under any condition. The finding of normal physiologic adjustments to submaximal rhythmic handgrip exercise with the surgical arm suggests that oxygen delivery during exercise was adequate.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Response of upper limb blood flow to handgrip exercise after Blalock-Taussig operation (for tetralogy of Fallot) or subclavian flap operation (for aortic isthmic coarctation). 272 10

The purpose of this study was to document the recovery of isometric contractile function following tourniquet ischemia. Male Wistar rats (N = 27) were subjected to unilateral hindlimb tourniquet ischemia of 0 hr (control, N = 6), 1 hr (N = 5), 2 hr (N = 5), 3 hr (N = 5) and 4 hr (N = 3). Following a 2-week recovery period, isometric force measurements were made from both gastrocnemii of each rat with the contralateral limb acting as the control side. Each muscle was analyzed for maximal twitch (Pt, N/g), maximal rate of rise of twitch tension (DP/dt, N/sec), time to peak tension (TPT, msec), half relaxation time (RT 1/2, msec), maximal tetanus (P0, N/g, at 100 Hz), and fatigue (Burke Fatigue Protocol). Pt, P0, and DP/dt were significantly different from control values (P less than 0.05) for all hours of tourniquet ischemia. A strong negative correlation (P less than 0.001) was found for twitch (R = -0.84), tetanus (R = -0.78), and maximal rate of force development (R = -0.83) with respect to increasing hours of ischemia. The recovery of isometric twitch and tetanic function following tourniquet ischemia is inversely related to the ischemic interval. This study quantified the relationship between muscle ischemia and recovery of function following a 2-week interval and stresses the functional physiological changes which occur in skeletal muscle following tourniquet ischemia.
 ...
PMID:Isometric contractile function recovery following tourniquet ischemia. 277 Feb 93

Normal compensatory mechanisms protect the central nervous system (CNS) from moderate hypoxia and ischemia; however, after more severe ischemia progressive brain hypoperfusion ensues and irreversible damage occurs. Ischemic brain injury remains greatly significant clinically and elucidating the determinants of ischemic neuronal injury and death continues to challenge researchers. Although altered perfusion and decreased energy charge may contribute to the production of irreversible damage, the distribution of lesions seen after insult does not correspond with the degree of ischemic blood flow impairment, nor can neuronal energy deprivation explain the cell damage. Other factors, such as derangements in astrocyte function, calcium homeostasis, free radical metabolism, acid-base regulation and excitatory neurotransmitters also probably mediate ischemic neuronal death. Continued investigation to establish the cellular pathophysiology of cerebral ischemia can guide rational research and therapeutic strategies.
 ...
PMID:Mechanisms of ischemic cerebral injury. 282 55

The effect of nadolol at a dose of 1 mg kg-1, i.v. on the ischaemic myocardial metabolism has been examined in the dog. Ischaemia was induced by ligating the left anterior descending coronary artery for 3 min, and nadolol was injected 5 min before ligation. Ischaemia caused myocardial metabolic changes; it decreased energy charge potential and inhibited glycolytic flux through phosphofructokinase reaction. Pretreatment with nadolol lessened the decrease in energy charge potential and the inhibition of glycolytic flux being caused by ischaemia. Nadolol may have a beneficial effect on the ischaemic myocardium.
 ...
PMID:Effect of nadolol, a beta-adrenoceptor blocking agent, on myocardial metabolism in the dog ischaemic heart. 288 50

Between 1983 and 1986, 23 athletes were evaluated for arm and hand complaints. Eleven players had symptoms of thoracic outlet compression. Severe arm fatigue (eight patients) and finger ischemia (three patients) were the presenting symptoms. In the remaining 12 athletes, symptoms of hand ischemia were predominant. Noninvasive testing with Doppler ultrasonography and duplex scanning (positional testing and finger systolic pressure recording) and cold immersion were used to aid in diagnosis. In the 11 athletes with thoracic outlet compression, arteriography confirmed the finding with compression of the subclavian artery in five, the axillary artery in one, both subclavian and axillary arteries in two, posterior humeral circumflex artery in one, and subclavian aneurysm in two. Compression of the suprascapular artery was identified in four, the subscapular artery in two, and the posterior humeral circumflex artery in one. Thrombosis of a first baseman's ulnar artery and occlusion of the palmar arch in a frisbee player were documented by arteriography. Decompression of the thoracic outlet consisted of anterior scalenectomy in five, pectoralis minor muscle division in one, and resection of both muscles in two. Removal of cervical rib with interposed vein graft was performed in the two players with arterial aneurysm. Hand ischemia in the remaining athletes was treated conservatively with Dextran-heparin infusion for acute ischemia. Repeat noninvasive study of all players demonstrated absence of compression in their playing position, and all have resumed their playing careers. Hand ischemia in athletes can be evaluated noninvasively and treated conservatively. Resection of hypertrophied muscles to decompress the thoracic outlet together with release of branch artery compression in selected athletes promotes perfusion to arm and shoulder muscles and helps to avoid the catastrophic complication of repetitive trauma leading to sudden arterial thrombosis.
 ...
PMID:Upper extremity arterial injury in athletes. 291 27

1. In previous studies on the adductor pollicis and biceps brachii muscles we suggested that motoneuron firing rates are inhibited by a reflex from the muscle during fatigue, since: the firing rates decline during a sustained maximal voluntary contraction (MVC); recovery of MVC firing rates is prevented if the fatigued state of the muscle is preserved for 3 min by local occlusion of its blood supply; and full recovery occurs during this time once the blood supply to the peripheral muscle is restored. These findings were confirmed in the present study for quadriceps contractions. 2. These results do not necessarily imply an inhibitory reflex. The lower firing rates recorded from the muscle fibers during an MVC following 3 min of postfatigue ischemia may have been caused by either reduced subject effort (decreased muscle activation by the CNS) or impaired peripheral impulse transmission under these conditions. The present experiments, carried out on the quadriceps and adductor pollicis muscles, were designed to test this alternative explanation. 3. For both muscles, MVC contractions were sustained for 40 s with a blood pressure cuff inflated to 200 mmHg. This was followed by 3 min ischemic rest and a second 20-s MVC before cuff release. Three minutes after the blood supply to the muscle was restored a third 20-s MVC was made. Single shocks were delivered to the muscle throughout to record twitches from the relaxed muscle (Tr) before and after each MVC, and any twitches super-imposed on the voluntary contractions (Ts). The degree to which the muscle could be activated by voluntary effort was assessed from the ratio [1 - Ts/Tr]. For adductor pollicis, changes in the amplitude of the evoked M-waves were also measured. 4. Spike frequencies were only recorded during quadriceps experiments. These declined by 30% during the initial 40-s MVC. No recovery was seen in the second MVC following 3 min ischemic rest, but full recovery occurred within 3 min of cuff release. 5. Failure to retain full muscle activation was frequently seen in all three MVCs. However, for many well-motivated subjects twitch occlusion showed no reduction in the degree to which either the adductor pollicis or quadriceps muscles could be activated voluntarily during the MVC executed after 3 min of ischemic rest compared with that performed 3 min after the blood supply had been restored.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Evidence for a fatigue-induced reflex inhibition of motoneuron firing rates. 303 78

The circumstances of the sudden death of a young healthy wrestler in the course of a wrestling match are described. The death occurred due to acute ischemia of the brainstem as a result of the acute interruption of blood flow to his vertebral-basal system, as a consequence of the injury or rupture of vertebral arteries, after injury of the neck. This interruption of the irrigation of the brainstem with blood provoked the sudden death of the athlete. The cause of the injury to the neck of the wrestler was the wrong position of his head (it was trapped between the mat and his own forearm), at the moment when the athlete was in the inferior disadvantaged position and his opponent was exerting a powerful but permissible effort to overthrow him. The combination of the wrong position of the head of the injured athlete and the forceful action of the wrestler in the offensive resulted in the overflexion and rotation of the head of the former and the (inevitable) damaging of his neck. Various predisposing factors effectively contribute to the injury, the main ones being the lack of warming up of the athlete, the premature fatigue of the athlete, minor injuries at the cervical segment of the vertebral column during the phases preceding the main injury, and the confrontation with an opponent of greater training age and superior fighting level. The only way to deal with similar, very rare indeed, incidents is to implement the set of preventive measures described.
 ...
PMID:Sudden death of a young wrestler during competition. 324 73

Shoulder pain correlated to manual labour is an increasing problem. The etiology is multifactorial and often unclear. High local muscle load and muscle ischemia in the supraspinatus muscle is present in elevated arm positions, as shown in several electromyographic studies. The purpose of this study was to evaluate intramuscular pressure (IMP) as a way to describe local muscle load in the supraspinatus muscle. Measurements were made in 15 arm positions, and with hand loads of 0, 1, or 2 kg weight, in 12 shoulders. The IMP was recorded with microcapillary infusion technique. The method was found to be suitable in recording IMP at rest and during exercise. High intramuscular pressures, i.e., above 50 mm Hg (6.7 kPa), were seen in moderate humeral abduction. The IMP increased further in abduction up to 90 degrees, where mean IMP was 122 mm Hg (16.2 kPa). Added hand load increased intramuscular pressure in all positions except in shoulder flexion of 135 degrees. The study thus demonstrated that intramuscular pressure offers important information about the load on the supraspinatus muscle in different positions of the arm. The results indicate that fatigue and shoulder pain related to elevated arm positions may be caused by muscle ischemia induced by the high intramuscular pressure present in these positions.
 ...
PMID:Intramuscular pressure in the supraspinatus muscle. 334 29

Fatigue, polarization level and excitability of striated muscle fibers from ischemia zone were studied on experimental rats under the tourniquet shock. It was established that violation-mediated contraction and fatigue of skeletal muscle was associated with a decrease in a number of muscle fibers with high level of MPP. The article discussed the mechanisms of fatigue and depolarization of muscle fibres in tourniquet shock.
 ...
PMID:[Dependence of skeletal muscle fatigue on the membrane polarization of the different types of muscle fibers in tourniquet shock]. 334 40

Isometric contractile function was studied after recovery in free, vascularized muscle transfer subjected to graded periods of intraoperative ischemia. Fifteen dogs had orthotopic replantation of their left gracilis muscles, with intraoperative ischemia times grouped as 0 (n = 3), 1 to 2 (n = 3), 2 to 3 (n = 4), or 3 to 4 (n = 5) hours. After recovery (mean 61.8 weeks), isometric twitch and tetanic tension and fatigue measurements were made in the replants and in the contralateral, control gracilis. On the average, replants were found to produce significantly less twitch (0.32 +/- 0.13 versus 0.49 +/- 0.24 N/g) and 75 Hz tetanic tension (2.2 +/- 0.9 versus 3.4 +/- 0.5 N/g) than controls. However, in several individual replants, 100% of control maximal tetanic tension was observed. Intraoperative ischemia time of up to 4 hours was not correlated with functional return. It is concluded that (1) full recovery is possible after free muscle transfer; (2) intraoperative ischemia, if less than 4 hours long, is not the primary determinant of functional recovery; and (3) factors besides intraoperative ischemia must be operative in producing the variability in recovery seen in this setting.
 ...
PMID:The effect of intraoperative ischemia on the recovery of contractile function after free muscle transfer. 335 Dec 55


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>