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At least 811 records · Page 45Linked to original sources
PubMed1994

Forearm blood flow responses to a nitric oxide synthase inhibitor in patients with treated essential hypertension.

OBJECTIVE: There is evidence that basal NO mediated vasodilatation is abnormal in patients with essential hypertension. Studies in animals suggest that treatment of hypertension may restore the nitric oxide system towards normal. The objective of this study was to examine basal nitric oxide mediated vasodilatation in patients with treated essential hypertension. METHODS: The forearm blood flow response to noradrenaline and NG-monomethyl-L-arginine (L-NMMA), a stereospecific inhibitor of nitric oxide synthesis, was compared in 11 patients with treated essential hypertension and 18 normotensive healthy controls. The results in the treated hypertensive patients were also compared with those in a previously reported group of seven untreated patients with essential hypertension. Drugs were infused locally into the brachial artery and forearm blood flow measured using venous occlusion plethysmography. RESULTS: In the healthy controls noradrenaline (60, 120, and 240 pmol.min-1) and L-NMMA (1, 2, and 4 mumol.min-1) produced similar reductions in resting forearm blood flow. In the patients with treated essential hypertension, at the same doses, noradrenaline and L-NMMA also produced similar reductions in forearm blood flow. There was no significant difference in the response to either noradrenaline or L-NMMA between the healthy controls and the treated hypertensive patients. There was also no significant difference in the response to noradrenaline or L-NMMA between the treated patients and the patients with untreated essential hypertension. However, the response to L-NMMA in all subjects correlated significantly with blood pressure, such that the responses in the treated patients lay between those of the healthy controls and the untreated patients. CONCLUSIONS: Basal nitric oxide mediated vasodilatation appears to be a continuum that varies with blood pressure. Reduction in blood pressure with medication moves the L-NMMA response nearer to that seen in healthy subjects. These results suggest that treatment of hypertension may restore NO mediated vasodilatation towards normal.

Adult↗
PubMed1994

Effects of S-nitroso-glutathione in the human forearm circulation: evidence for selective inhibition of platelet activation.

OBJECTIVE: Nitric oxide (NO) is a vasodilator and inhibitor of platelet function. The clinical use of NO donors as inhibitors of platelet activation is limited by their concomitant hypotensive effect. S-nitroso-glutathione (GSNO) has a significant antiplatelet effect at doses that cause only a small decrease in blood pressure in rats. The aim of this study was to examine the antiplatelet and vasodilator properties of this nitrosothiol in the human forearm. METHODS: Forearm blood flow was measured by forearm occlusion plethysmography in five healthy males. Ex vivo platelet aggregation to ADP was performed in a platelet ionised calcium lumi-aggregometer. RESULTS: Intra-arterial infusion of GSNO (0.2, 1, and 5 nmol.min-1) resulted in inhibition of ADP (1-10 microM) induced platelet aggregation. This inhibition was submaximal for 0.2 and maximal for 1 and 5 nmol.min-1. However, the antiaggregatory effect observed at the lowest dose of GSNO was accompanied only by a threshold increase in forearm blood flow. CONCLUSIONS: These results show that GSNO is more effective as an inhibitor of platelet activation than as a vasodilator, suggesting that it is possible to achieve selective antiplatelet and potentially antithrombotic effects with NO donors.

Adenosine Diphosphate↗
PubMed1989

Effects of age on cutaneous circulatory response to direct heat on the forearm.

To investigate the effects of age on the response of skin blood flow in the forearm to direct heat, three groups of 20 male subjects each--young (20-39 yr); middle-aged (40-59 yr) and older (60-79 yr)--consented to have skin blood flow measured in the forearm by a TSI Model 403 laser Doppler flowmeter. This instrument detects changes in red blood cell velocity (LDV) in flow-active vessels and the volume of red blood cells flowing through these vessels (LDO). With the forearm in a 30 degrees C water bath there were no significant between-group differences in LDV or LDO. Elevating bath temperature to 35 degrees C elicited a significant increase in LDO in all three groups, but LDV did not significantly change. Increasing temperature to 40 degrees C elicited significant increases in both LDO and LDV with the former being of greater magnitude. At this temperature LDV values in both the middle-aged and older groups were significantly lower than those of the young subjects. Expressing the data during heating as percent change from 30 degrees C showed a significantly lower volume (LDO) response in the older group at 35 and 40 degrees C and a significantly lower LDV response at 40 degrees C for both the middle-aged and older subjects in comparison to the young group. It is concluded that aging decreases the response of cutaneous blood flow in the forearm to the direct effects of heat.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

Calcium intake and the incidence of forearm and hip fractures among men.

High calcium intakes are thought to be associated with strong bones and lower risk of fractures. However, findings from epidemiologic studies have not been consistent. In addition, the vast majority of such studies were conducted among women, leading to a relative lack of data concerning men. The objective of this study therefore was to investigate the relation between adult calcium intake and risk of fractures among men in the Health Professionals Follow-up Study (HPFS). During 331,234 person-years of follow-up over an 8-y period, 201 forearm and 56 hip fractures due to low or moderate trauma were reported among 43,063 men 40-75 y of age in 1986 when they first completed a questionnaire about diet and lifestyle factors. After controlling for age, smoking status, body mass index (BMI), physical activity, alcohol consumption and total energy intake, the relative risk (RR) of forearm fractures for men in the highest quintile of calcium intake (from foods plus supplements) compared with those in the lowest quintile was 0.98 [95% confidence interval (CI) = 0.59-1.61; P for trend = 0.78]; for hip fractures, the comparable RR was 1.19 (95% CI = 0.42-3.35; P for trend = 0.58). Relative risks for consuming >2.5 glasses (600 mL) of milk per day compared with one (240 mL) or fewer per week were 1.06 (95% CI = 0.69-1.62; P for trend = 0.82) for forearm fractures and 0.97 (95% CI = 0.39-2.42; P for trend = 0.56) for hip fractures. In conclusion, these results do not support a relation between calcium intake and the incidence of forearm or hip fractures in men.

Adult↗
PubMed1992

Risk factors for fractures of the distal forearm and proximal humerus. The Study of Osteoporotic Fractures Research Group.

The Study of Osteoporotic Fractures is a prospective cohort study begun in 1986 that includes 9,704 women aged 65 years and older from Maryland, Minnesota, Oregon, and Pennsylvania. A total of 171 women suffered fractures of the distal forearm, and 79 women had fractures of the proximal humerus during the first 2.2 years of follow-up. Most fractures at both sites occurred as a result of a fall. Low bone mineral density was a strong predictor of these fractures; comparing those in the lowest quintile of bone mineral density in the distal radius with those in the highest quintile, the rate ratio was 4.1 for fractures of the distal forearm and 7.5 for fractures of the proximal humerus. Other factors associated with an increased rate of distal forearm fracture independently of low bone mineral density included poor visual acuity, number of falls in the year before baseline, and frequent walking. Factors that appeared to be independently associated with an increased rate of fracture of the proximal humerus included a recent decline in health status, insulin-dependent diabetes mellitus, infrequent walking, and several indicators of neuromuscular weakness such as inability to stand with feet in a tandem position for more than a few seconds. These data support the hypothesis that distal forearm fractures often occur as a result of a fall in women with low bone mineral density who are relatively healthy and active and have good neuromuscular function, while fractures of the proximal humerus tend to occur as a result of a fall in women with low bone mineral density who are less healthy and less active than average and who have poor neuromuscular function.

Age Factors↗
PubMed1987

The free ulnar forearm flap.

Many flaps have been described based on the septocutaneous perforators; these have many advantages for the coverage of soft tissue defects. The ulnar forearm flap described by Lovie is a septocutaneous flap based on the septocutaneous perforators of the ulnar artery. We report the use of this flap in 2 patients who required soft tissue coverage. The ulnar forearm flap has the advantages of thin and pliable skin, constant and large pedicle, and the technical possibility of combination with the muscles, sensory or motor nerve, and ulna. Comparing it with the radial forearm flap, there is no possibility of exposure of flexor tendons, which usually results in the good take of skin grafts. After skin grafting, the donor scar is unnoticeable because of its position on the forearm. This flap is for the coverage of thin defects that require mobility, such as in the extremities or the intraoral region. It also could be used for the coverage of hand or arm defects as a distally or proximally based island flap, respectively.

Forearm↗
PubMed1989

The vascular microanatomy of skin territory of posterior forearm and its clinical application.

We have undertaken a microanatomical study of a new donor site--the posterior forearm territory--on 43 cadaver arms. Two axial arteries were found, and both the fasciocutaneous flap and the fascial flap could be elevated with the two arteries on the posterior forearm. The posterior forearm flap was transferred to the hand to repair deformities of the wrist, the first web space, the dorsal hand, and the metacarpophalangeal joints in eight cases. The result was very satisfactory. The posterior forearm flap is near the hand, easy to perform, and reliable. It is a one-stage operation and does not sacrifice a main artery. In this article we demonstrate our own ideas about flap extension, which is valuable for clinical application.

Adult↗
PubMed1998

Hemoglobin oxygenation of venous-perfused forearm flaps.

To understand how venous flaps function we investigated whether blood flowing via the venous network reaches the capillaries of the skin. While measuring spectrophotometrically intracapillary hemoglobin oxygenation of fasciocutaneous forearm flaps in 12 patients, flap perfusion was changed by manipulating nutrient vessels. Conventionally perfused radial forearm flaps had an intracapillary hemoglobin oxygenation of 51% to 74% but decreased to 6.9% to 12.2% within 90 to 120 minutes after arterial occlusion and perfusion only from the cephalic vein entering the flap cranially (type I venous flap). Radial forearm flaps without any vascular connection showed no oxygenated hemoglobin after 180 to 240 minutes in the capillary network. After microsurgical vein anastomosis and release of the blood flow only via the cephalic or accompanying veins, hemoglobin oxygenation returned immediately to about 10%. We conclude from our results that there is actual capillary perfusion, albeit very slight, in type I venous forearm island flaps.

Adult↗
PubMed2001

Creating two independent fasciocutaneous free flaps from a single radial forearm donor site.

The authors describe the creation of two independent fasciocutaneous free flap units from a single radial forearm donor site. After the radial forearm flap is elevated in the standard manner, based on the entire length of the radial artery, the individual flap units are developed as island flaps based on the proximal and the distal radial artery respectively by transecting the radial artery, its accompanying veins, and the cephalic vein. Thus, two independent radial forearm free flaps are created from a single donor site: The proximal one has antegrade flow and the distal one has retrograde flow. The individual free flap units were transferred, and microvascular anastomoses were performed simultaneously by two surgical teams. This technique was used in 2 patients presenting with bilateral foot defects that required reconstruction with a thin, reliable flap such as the radial forearm flap.

Adult↗
PubMed2001

Soft-Tissue reconstruction of the face using the folded/multiple skin island radial forearm free flap.

Resection of malignant soft-tissue tumors of the face often results in defects of skin, lining, and contour. When local tissues are unavailable, the folded/multiple skin island forearm free flap has been used to correct complex lining, skin, and contour defects concomitantly. This study is a retrospective review of all patients reconstructed with folded/multiple skin island forearm flaps from 1992 to 2000. Facial defects included facial skin, mucosal lining, and intervening soft tissue. Reconstruction was immediate and was not combined with another local flap. There were 17 patients (mean age, 61 years). Five patients had cutaneous malignancies and 12 patients had either mucosal or salivary gland malignancy. Defects were of the cheek and nose either alone or in combination. Defects ranged from 9 to 54 cm2. Nine patients had defects of either the skin or the mucosa with an associated soft-tissue component. These were reconstructed with a folded forearm flap with one skin island. Eight patients had full-thickness defects and were reconstructed with a folded flap with two skin islands. Flap survival was 100%. One case required reexploration for hematoma. Aesthetic results were good to excellent in 76% of patients. Delayed wound healing at the donor site occurred in 2 patients (11%). The folded/multiple skin island forearm flap is a useful tool for single-stage reconstruction of complex facial defects requiring replacement of skin, lining, and intervening soft tissue. Good to excellent aesthetic results can be expected in most patients.

Adult↗
PubMed1994

Nutritional and metabolic variables correlate with amino acid forearm flux in patients with severe head injury.

OBJECTIVE: To measure the arterial-venous amino acid flux across the forearm muscle in patients with severe head injury. DESIGN: Prospective, interventional study. SETTING: Level I trauma hospital in the neurosurgery intensive care unit (ICU) at a university medical center. PATIENTS: Eight nonsteroid-treated patients with severe head injury. INTERVENTIONS: Patients were prospectively randomized to receive either standard or supplemental intravenous zinc therapy. MEASUREMENTS AND MAIN RESULTS: Net forearm alanine, glutamine, tyrosine, phenylalanine, and branch-chain amino acid forearm flux were measured and compared with metabolic markers of energy expenditure and nitrogen excretion. There was a significant inverse relationship between the measured energy expenditure/predicted energy expenditure ratio and glutamine flux (r2 = .62; p < .05). The patients with the highest measured energy expenditure/predicted energy expenditure ratio had the greatest release of glutamine from forearm muscle. Nitrogen balance was significantly correlated with leucine flux (r2 = .53; p < .05) and with isoleucine flux (r2 = .67; p < .05). The patients with the most positive nitrogen balance had the least release of branch-chain amino acids from skeletal muscle. Tyrosine flux was highly correlated with net amino acid flux (r2 = .76; p < .01). Tyrosine flux was therefore indicative of overall muscle catabolism. Four patients had an overall negative flux of amino acids from skeletal muscle. Three patients had an overall negative flux of branch-chain amino acids. CONCLUSIONS: This preliminary descriptive report suggests that increased skeletal muscle efflux of amino acids correlates significantly with metabolic variables of hypermetabolism and hypercatabolism in nonsteroid-treated, head-injured patients.

Adult↗
PubMed2000

Gait with and without forearm crutches in patients with total hip arthroplasty.

There is considerable variation between centres in the use of forearm crutches in the rehabilitation of patients with total hip arthroplasty who are capable of full weight bearing. This study aimed to compare the gait of patients with total hip arthroplasty walking with and without crutches. The gait analysis in 19 patients included the assessment of kinematics, kinetics and the kinesiological electromyographic activity of lower limb and trunk muscles. With the forearm crutches patients walked with a reduced cadence, a longer stride length and more symmetrically (P < 0.05). The activity of the gluteus medius, vastus medialis and lateralis, and erector spinae muscles of the affected and of the vastus medialis muscle of the unaffected side decreased significantly (P < 0.05). Furthermore, seven subjects displayed an abnormal activation pattern of the affected hip abductor when walking with forearm crutches, characterized by a second burst during swing (n = 5) or a tonic pattern (n = 2). It is concluded that the use of forearm crutches resulted in a symmetrical gait pattern. The reduced activity of relevant pelvi-trochanteric muscles and the disturbed activation pattern of the affected hip abductor when walking with crutches might indicate that patients should walk unaided as soon as possible to provide a more efficient muscular training under dynamic conditions.

Aged↗
PubMedDate not supplied

Photographic measurement of volar forearm skin movement with wrist extension: the influence of elbow position.

An important function of skin is to allow joint range of motion to occur. An assumed clinical relationship exists between joint movement and skin pliability. The purpose of this research was to document skin movement of the forearm and wrist with photography, to quantify the amount of skin movement during wrist extension, and to investigate the influence of elbow positions on forearm skin movement. Twenty volunteers had markings placed on the skin of the volar forearm. Each subject performed the motion of wrist extension in two elbow test positions of flexion and extension. Photographs were taken of the skin markings at the beginning and end of wrist extension. A significant difference was found in the amount of forearm skin movement that occurred when the elbow was extended and flexed (p < 0.001). These results substantiate the use of multijoint range of motion during burn rehabilitation.

Adult↗
PubMed1987

Dopamine produces forearm vasodilatation following alpha-adrenoceptor blockade by an action on vascular dopamine (DA1) receptors in man.

The purpose of this study was to investigate the receptor type mediating dopamine-induced forearm vasodilatation following alpha-adrenoceptor blockade. Forearm blood flow (FBF) was measured using venous occlusion plethysmography in normal volunteers. Intra-arterial (i.a.) dopamine alone produced variable and small changes in FBF. However, following alpha-adrenoceptor blockade with phenoxybenzamine, dopamine infusion resulted in forearm vasodilatation in the infused arm. This effect was not antagonized by the beta-adrenoceptor antagonist propranolol, but was antagonized by the vascular dopamine receptor antagonist, sulpiride, the (d) enantiomer being more active than the (l). It is concluded that i.a. dopamine induces forearm vasodilatation following alpha-adrenoceptor blockade by an action on vascular dopamine (DA1) receptors similar to those described in the renal and mesenteric vasculature of other species.

Adrenergic alpha-Antagonists↗
PubMed1995

On the existence of functional angiotensin II receptors on vascular sympathetic nerve terminals in the human forearm.

OBJECTIVE: The existence of presynaptic angiotensin II receptors, modulating the release of the sympathetic neurotransmitter norepinephrine, was examined in the perfused human forearm model. DESIGN AND METHODS: In three groups out of a total of 20 healthy volunteers, intra-arterial infusions of tracer amounts of tritiated norepinephrine were given to measure forearm spillover and total plasma appearance rate of norepinephrine during intra-arterial infusions of angiotensin II (0.02, 0.2 and 2 ng/kg per min), methoxamine (0.08, 0.4 and 2 micrograms/kg per min) to produce vasoconstriction by stimulating alpha 1-adrenoceptors and saralasin (0.5 ng/kg per min) to block angiotensin II receptors. Postganglionic sympathoneural activity was stimulated by intravenous infusion of sodium nitroprusside (about 1.3 ng/kg per min) or attenuated by intravenous infusion of trimethaphan (about 1 mg/min). RESULTS: Angiotensin II failed to increase the spillover and total plasma appearance rate of norepinephrine, when given without additional treatment or during sodium nitroprusside or trimethaphan administration. In contrast, the spillover of norepinephrine even decreased during angiotensin II administration, both before and during intravenous sodium nitroprusside administration, probably because of angiotensin II-induced forearm vasoconstriction. Similar vasoconstrictor doses of angiotensin II and methoxamine produced similar changes in spillover and total plasma appearance rate of norepinephrine. The highest dose of angiotensin II increased diastolic blood pressure by 9% and decreased the pulse rate by 6%. Saralasin affected the spillover and total plasma appearance rate of norepinephrine neither before nor during intravenous sodium nitroprusside infusion. CONCLUSION: The present results fail to support the view that angiotensin II receptors exert stimulatory modulatory effects on norepinephrine release from sympathetic nerves in the human forearm, at rest or during changes in sympathoneural outflow.

Adult↗
PubMed1994

No functional involvement of 5-hydroxytryptamine1A receptors in nitric oxide-dependent dilatation caused by serotonin in the human forearm vascular bed.

The vascular effects of serotonin (5-hydroxytryptamine, 5-HT) are complex and heterogeneous. In human forearm, we showed that low doses of 5-HT cause marked but transient vasodilatation followed by a persistent vasodilator response. In in vitro and in animal experiments, 5-HT induced release of nitric oxide (NO) through stimulation of endothelial 5-HT1-like receptors. In the present study, we investigated involvement of the "NO pathway" and possible involvement of the 5-HT1A receptor subtype in 5-HT-induced persistent vasodilator response. In 8 healthy volunteers, we infused 5-HT (0.1, 0.3, and 1 ng/kg/min) and the selective 5-HT1A receptor agonist flesinoxan (15, 45, and 150 ng/kg/min) intraarterially (i.a.) with NG-monomethyl-L-arginine (L-NMMA 30 micrograms/kg/min) or saline. Forearm blood flow (FBF) was measured by automated R-wave-triggered venous occlusion plethysmography. Forearm vascular resistance (FVR) was derived from simultaneously recorded i.a. blood pressure (BP) and FBF. 5-HT dose-dependently decreased FVR (p < 0.001). The persistent vasodilator response to 5-HT appears to be mediated by NO release, as suggested by its complete abolition by L-NMMA (p < 0.001). Flesinoxan decreased FVR slightly, but only at high doses (p < 0.05). The present findings indicate that 5-HT1A receptors are not functionally involved in 5-HT-mediated vasodilatation in human forearm.

Adult↗
PubMed1999

Long-term treatment with eicosapentaenoic acid augments both nitric oxide-mediated and non-nitric oxide-mediated endothelium-dependent forearm vasodilatation in patients with coronary artery disease.

Long-term treatment with eicosapentaenoic acid (EPA) is known to improve impaired endothelium-dependent relaxations of atherosclerotic blood vessels in animals and humans. However, it remains to be determined which mechanisms are involved in this beneficial effect of EPA. In this study, we investigated our hypothesis that EPA improves both nitric oxide (NO)-mediated and non-NO-mediated endothelium-dependent vasodilatation in patients with coronary artery disease. The study included eight patients with documented coronary artery disease. The forearm vascular responses to the endothelium-dependent vasodilator acetylcholine and substance P were examined before and after intraarterial infusion of NG-monomethyl-L-arginine (L-NMMA). Same measurements were repeated after the treatment with EPA (1,800 mg/day) for 6 weeks. The long-term treatment with EPA augmented forearm blood-flow response to both acetylcholine and substance P. Furthermore, acute administration of L-NMMA significantly inhibited the EPA-induced augmented response to acetylcholine but not that to substance P. The forearm vascular response to sodium nitroprusside was unchanged by the EPA treatment. These results indicate that long-term treatment with EPA augments both NO-dependent and non-NO-dependent endothelium-dependent forearm vasodilatation in patients with coronary artery disease. Thus the beneficial effects of EPA appear to extend to non-NO-dependent mechanism(s).

Acetylcholine↗
PubMed2000

Transient improvement of acetylcholine responses after short-term oral L-arginine in forearms of human heart failure.

Patients with heart failure exhibit impaired endothelium-dependent vasodilation. Although brief intraarterial administration of L-arginine improves endothelium-dependent vasodilatation in these patients, long-term oral supplementation is ineffective. To resolve these conflicting findings, we examined the effect of a single, short-term oral dose of L-arginine on serial, hourly forearm vascular responses to acetylcholine, sodium nitroprusside, and norepinephrine. Eighteen patients with heart failure were randomly allocated in a double-blinded, crossover study to receive either a single 20-g oral dose of L-arginine or placebo. Vascular responses were measured by forearm venous occlusion plethysmography before and at 60, 120, and 180 min after dosage. Blood was obtained for measurement of L-arginine and nitric oxide metabolite levels. Oral L-arginine increased plasma levels by fourfold at 60, 120, and 180 min. Vasodilatation to acetylcholine, 37 microg/min, was significantly enhanced at 60 min (percentage increase in forearm blood flow: placebo, 413 +/- 64%; L-arginine, 587 +/- 94%; p < 0.05), discernible at 120 min (p = 0.058) but no longer apparent at 180 min. Neither basal forearm blood flow, sodium nitroprusside, nor norepinephrine responses nor plasma levels of nitrite and nitrate were altered. We conclude that although short-term oral supplementation with L-arginine produced marked sustained elevation of plasma levels of L-arginine in patients with heart failure, responses to acetylcholine were only transiently improved.

Acetylcholine↗