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Biomedical subjects

P Hanson

Publications and source records attributed to P Hanson.

At least 55 records · Page 3Linked to original sources
PubMed1995

Comparison of arterial occlusion and ischaemic exercise for the study of vasodilatation in the human calf.

1. Calf blood flow was measured by venous occlusion plethysmography to compare two stimuli for eliciting maximal calf vascular conductance: (i) 10 min of arterial occlusion and (ii) isolated exhaustive calf exercise with ischaemic occlusion. The subjects were semi-supine with the calf in position for immediate blood flow measurements after release of the occluding cuff. Three groups of subjects were studied: young [35 years (SD 9, n = 9)], old [57 years (SD 5, n = 10)] and patients with congestive heart failure [63 years (SD 7, n = 7)]. 2. Occlusion and ischaemic exercise were equally effective in producing maximal calf vascular conductance in each of the subject groups. Maximal calf vascular conductance (ml min-1 100 ml-1 mmHg-1) was equivalent in the young [ischaemic exercise 0.54 (SEM 0.03), occlusion 0.54 (SEM 0.05)] and old [ischaemic exercise 0.47 (SEM 0.05), occlusion 0.48 (SEM 0.04)] subjects. However, patients with congestive heart failure exhibited significantly reduced maximal calf vascular conductance [ischaemic exercise 0.20 (SEM 0.02), occlusion 0.20 (SEM 0.01)]. 3. Analysis of the curves, generated by plotting serial calf vascular conductance values obtained immediately and every 15 s after occlusion cuff release for 165 s, revealed differences in the pattern of vasodilatation after occlusion and ischaemic exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Squatting revisited: comparison of haemodynamic responses in normal individuals and heart transplantation recipients.

BACKGROUND: Squatting produces a prompt increase in cardiac output and arterial blood pressure which is accompanied by an immediate decrease in heart rate and forearm vascular resistance. The rise in cardiac output and blood pressure has been attributed to augmented venous return from compression of leg veins, while the decreases in heart rate and forearm vascular resistance are probably due to activation of cardiopulmonary and arterial baroreflexes. Haemodynamic patterns in nine normal men and six heart transplant recipients during 2 min of squatting were examined to determine the role of cardiac innervation in the mediation of these responses. METHODS: Stroke volume was monitored by ensemble averaged thoracic impedance cardiography and blood pressure was determined with an Ohmeda fingertip plethysmograph. These techniques provided continuous measurements which were capable of detecting transient and non-steady state changes. Forearm blood flow was measured with venous occlusion plethysmography. Measurements were obtained after 3 min of quiet standing, immediately after squatting, and at 20, 60, and 120 s of sustained squatting. RESULTS: Both groups exhibited similar increases in stroke volume index (normal individuals 10.5 ml/m2; heart transplant recipients 10.3 ml/m2) and mean arterial pressure (normal individuals 8.5 mm Hg; heart transplant recipients 5.0 mm Hg) which were sustained throughout squatting. Each group also showed an initial decrease in peripheral resistance (normal individuals 3.6 units; heart transplant recipients 7.7 units) followed by a return to baseline values after 20 s. Heart rate decreased in normal individuals (10 beats/min) but was unchanged or minimally increased (2 beats/min) in heart transplant recipients. Forearm vascular resistance was conspicuously decreased in normal individuals (47.8 units) but only minimally (20.9 units) and not significantly in heart transplant recipients. CONCLUSIONS: The major haemodynamic responses to squatting (increased cardiac output and blood pressure) are similar in normal individuals and heart transplant recipients. These responses are primarily due to augmented venous return and are not altered by cardiac denervation. Both groups also exhibited a transient decline in peripheral vascular resistance which is most likely mediated by arterial baroreflexes activated by the acute rise in arterial blood pressure. The absence of a significant decrease in forearm vascular resistance in heart transplant recipients suggests that this response is partially mediated by cardiopulmonary or ventricular baroreflexes or that local forearm flow mediated vasodilatation remains impaired after heart transplantation.

Adult↗
PubMed1994

Hemodynamic and volumetric response of the normal left ventricle to upright tilt testing.

The purpose of this study were to determine the specificity of the head-up tilt test in normal subjects when a graded isoproterenol infusion is used, and to evaluate the role of dynamic ventricular volume change during head-up tilt as a mechanism of syncope. We prospectively studied 12 normal volunteers, each of whom underwent an upright tilt test for 10 minutes at 80 degrees with and without an infusion of isoproterenol. A subgroup of five subjects had a third tilt test during administration of a combination of esmolol and isoproterenol. Blood pressure, heart rate, and left ventricular volumes and flow (obtained with Doppler echocardiography) were recorded in the following sequence: while supine, during upright tilt, while supine with isoproterenol, and during upright tilt with isoproterenol. During the initial head-up tilt, one subject had syncope. An additional eight subjects had presyncope or syncope during head-up tilt with isoproterenol. The remaining three subjects were asymptomatic. In subjects with syncope or near-syncope ("responders"), heart rate increased with isoproterenol but decreased markedly, to 76 +/- 5 beats/min, by the end of the protocol. Systolic blood pressure rose slightly above baseline during isoproterenol but fell from 118 +/- 4 to 85 +/- 5 mm Hg during head-up tilt with isoproterenol. The three asymptomatic subjects had only one significant change, an increase in heart rate with isoproterenol. In the five responders undergoing three tilt tests, left ventricular volume decreased significantly at end diastole (94 +/- 25 vs 58 +/- 22 ml) and end systole (34 +/- 13 vs 18 +/- 6 ml) when supine baseline is compared with initial upright tilt.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1994

The anatomy of the iliolumbar ligament.

During routine autopsies and anatomical dissections the anatomy of the iliolumbar ligament was studied and determined. In previous studies and literature, the ligament has been described to consist of three to five parts. We found the ligament to consist of only two parts: the anterior part and the posterior part, both attaching to the L5 transverse process. The insertion of the ligament has also been mentioned previously as attaching to the iliac crest. Both parts of the ligament were found to inset to the upper part of the iliac tuberosity, significantly lower than the iliac crest. The iliolumbar ligament cannot be visualized from the dorsal side before dissecting through all the lower back muscles and their fascias. We also found no evidence of any ligament part attaching to the L4 transverse process.

Adolescent↗
PubMed1994

Paired box gene expression in Wilms' tumor.

Wilms' tumor (WT) is an embryonal renal neoplasm with features resembling fetal kidney development. A family of genes potentially involved in WT induction is called the paired box (PAX) gene family. In this study we examined by Northern blot analysis the expression of several PAX genes in a variety of WTs and other childhood neoplasms. RNA was isolated from four primary WTs and 12 WTs propagated in nude mice (heterotransplant), as well as from a variety of other childhood renal and nonrenal embryonal tumors. RNA samples were electrophoretically separated in 1.2% agarose gels, transferred to nylon membranes, and hybridized to random primer-labeled PAX2, PAX8, and WT1 probes. Membranes were then exposed to x-ray films at -70 degrees C with intensifying screens. PAX2 and WT-1 expression were seen in all four primary WTs; PAX8 was seen in three of the four primary WTs. Of the 12 heterotransplant Wilms' tumors, PAX2, PAX8, and WT1 were concomitantly expressed in seven tumors. Another heterotransplant WT expressed WT1 alone. Expression of these three genes, with one exception, was not seen in the other childhood renal and nonrenal solid tumors. The PAX genes are transcriptional regulators; their protein products bind to specific DNA segments and control gene expression. Their role in the pathogenesis of Wilms' tumor and their interaction with WT1 are unclear. Elucidation of the functional significance of the PAX genes will provide important insights into not only the pathogenesis of WT but also the molecular control of the developing kidney.

Animals↗
PubMed1994

Influence of muscle length and force on endurance and pressor responses to isometric exercise.

Experiments were performed to determine whether endurance time, mean arterial pressure, or heart rate was related to either muscle length or external torque production in humans during isometric knee extension. Eight men and nine women performed isometric knee extension to the endurance limit at each of three muscle lengths, determined by knee angles of 40 degrees (0.698 rad, shortest), 60 degrees (1.047 rad, intermediate), and 90 degrees (1.571 rad, longest), and at intensities of 30 and 50% maximal voluntary contraction (MVC). Knee extension forms an ascending-descending length-torque curve, and lengths were chosen to result in different external torques. MVC was greatest at a knee angle of 60 degrees (P < 0.05 vs. 40 degrees, 90 degrees), with no significant difference between 90 degrees and 40 degrees. Endurance time was inversely related to muscle length, independent of torque production, at 30% MVC [40 degrees, 395 +/- 139 (SE); 60 degrees, 237 +/- 60; 90 degrees, 165 +/- 51 s; P < 0.05 vs. each other] and 50% MVC (40 degrees, 176 +/- 64; 60 degrees, 137 +/- 40; 90 degrees, 85 +/- 23 s; P < 0.05 vs. each other). Evidence is presented that endurance is a function of internal muscle force and not resultant external torque. The experimental design allowed the relationship of external torque and cardiovascular responses to be examined independent of exercise intensity. Muscle mass was also controlled in that the same muscle group was involved in all contractions. There were no differences in mean arterial pressure, heart rate, or rating of perceived exertion at any percentage of endurance time under any condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Benign osteonecrosis of vertebral body versus neoplastic lesions. Limitations of CT and magnetic resonance imaging].

A case of vertebral necrosis of L4 is reported in a young woman without previous steroid therapy. Only the intraoperative histological examination was able to confirm the diagnosis as a benign vertebral collapse, because the CT scan and MR imaging were suggestive of a malignant involvement. The authors report the various criteria proposed to distinguish benign and malignant vertebral collapse with magnetic resonance imaging. These equivocal criteria should be viewed within the context of tissue replacement within the necrotic area during the evolution. Transpedicular biopsy is emphasized. Only the histological examination is specific and allows right planning of the surgical procedure.

Adult↗
PubMed1994

Adding beta-2 agonism does not improve beta-1 blockade exercise responses in hypertensives.

We tested the hypothesis that celiprolol, a beta-1 adrenoceptor antagonist with the ancillary property of beta-2-mediated vasodilation, would increase blood flow to active muscles during exercise and result in less impairment of exercise performance compared with the beta-1 antagonist atenolol. After an initial 3-wk washout phase, 11 untrained hypertensive men participated in a 6-wk crossover study of the two drugs. Each treatment phase was followed by a 3-wk placebo phase. Resting forearm and calf vascular resistance measured by venous occlusion plethysmography and submaximal and maximal bicycle ergometry exercise responses were evaluated at the end of each treatment and placebo phase. Celiprolol significantly decreased resting forearm and calf vascular resistance whereas atenolol had no significant effect. Neither beta-blocker significantly affected submaximal exercise oxygen uptake, rate of perceived exertion, minute ventilation, or respiratory exchange ratio. Both beta-blockers significantly and similarly decreased peak oxygen uptake; celiprolol 23.9 +/- 1.7, atenolol 24.9 +/- 1.7, placebo 27.3 +/- 1.3 ml.kg-1.min-1. Our findings suggest that during exercise while on beta-blockade, other factors such as sympathetic vasoconstriction or local metabolic vasodilation may override beta-2-mediated vasodilation. Thus, the addition of beta-2 agonism to beta-1 antagonism decreases resting vascular resistance but offers no advantage over conventional beta-1 blockade therapy during exercise.

Adrenergic beta-1 Receptor Antagonists↗
PubMed1994

Exercise testing and training in patients with chronic heart failure.

Chronic heart failure (CHF) is a syndrome of impaired left ventricular (LV) function and cardiac output reserve that is associated with secondary compensatory adaptations including: LV hypertrophy and dilation, neuroendocrine activation, and vasoconstriction and redistribution of peripheral blood flow. The primary limitation in CHF is exercise intolerance characterized by fatigue and/or dyspnea during mild to moderate exertion. These symptoms are primarily attributed to impaired nutrient blood flow, cellular atrophy, and loss of oxidative function in skeletal muscle. Functional capacity in CHF is usually classified into four categories determined by symptom-limited exercise testing: normal > or = 7 METs; mild 5-7 METs; moderate 3-5 METs, severe < 3 METs. Exercise capacity in CHF is frequently unrelated to resting or exercise measures of LV function, e.g., LV ejection fraction (LVEF) and LV end diastolic pressure (LVEDP). Peak exercise heart rate and blood pressure are progressively attenuated in CHF due to baroreflex dysfunction and beta-receptor down regulation. Exercise training studies in selected patients with CHF (mild to moderate) have reported significant increases in peak VO2max, attributed to increases in peak leg blood flow O2 transport. Heart rate and lactate production during submaximal exercise are reduced compared with pretraining values. Potential training complications in patients with CHF include dysrhythmia, hypotension, and deterioration of cardiac status. The major benefit of moderate exercise training is improvement in tolerance to daily activities. However, the long term effect of exercise training on prognosis is currently not established.

Exercise Test↗
PubMed1994

Dyskinesia of the superior oesophageal sphincter: assessment and treatment.

Pharyngo-oesophageal dyskinesias present a common symptomatology associated with those difficulties in swallowing for which the radio-manometric assessment is well known. Radiology, nevertheless, with an overall analysis of deglutition and its iatrogenic complications, as well as manometry of the superior oesophageal sphincter (OSS) with its diversity of results, according to the material, techniques, age, sex and stress involved, has convinced us of the necessity for a supplementary dynamic examination. Electromyography (EMG), simultaneously by the inferior constrictor (IC) and cricopharyngeal (CP) muscles, analyses with precision the electric activity of these two muscles, as well as the pharyngosphincteral synchronism. It is an easy examination, reproducible and without complications. In less than one year, nineteen patients suffering exclusively from a pharyngo-oesophageal dyskinesia benefited by this complete assessment. The secondary aetiologies are clearly predominant. Gastro-oesophageal reflux represents a quarter of those detected by an anamnesis alone. EMG detects 68% of functional anomaly of the OSS; manometry finds 47% and radiology 32%. Extramucosal myotomy of the OSS concerns incomplete or uncoordinated relaxation, preferentially by left cervical approach. The preliminary results, both clinical and manometric, are very satisfactory.

Aged↗
PubMed1993

Skin potential recordings during cystometry in spinal cord injured patients.

In order to investigate autonomic mechanisms associated with bladder filling and bladder contraction, skin potentials from the hands and the feet of 32 spinal cord injured patients were recorded during cystometry. All had a complete clinical loss of motor and sensory function below the lesion, but in 3 patients, the autonomic lesion was electrophysiologically assessed as incomplete. In patients with a complete autonomic lesion, any rise in intravesical pressure associated with bladder hyperreflexia induced SP responses below the level of the lesion. SP responses were never obtained during bladder filling, as the intravesical pressure remained low. These results tend to confirm those of Guttmann and Whitteridge, but differ in so far as SP responses at the foot were a regular finding in all paraplegic and in most tetraplegic patients. Furthermore, bladder contraction failed to elicit SP responses below the level of the lesion in patients with an incomplete autonomic lesion. This study emphasises the importance of assessing the integrity of the autonomic nervous pathways when dealing with autonomic mechanisms in spinal cord injured patients. The possible relation between SP responses and bladder neck dysfunction is further discussed.

Cystoscopy↗
PubMed1993

Sacral reflex latencies in tethered cord syndrome.

We performed electrophysiologic evaluation in three adult patients with diagnosis of tethered cord syndrome confirmed by magnetic resonance imaging. In addition to lower motor neuron lesion signs in the lumbar and sacral myomeres we noticed shortened latencies for the H and bulbocavernosus reflexes. H reflex latencies ranged from 23.3 to 26.0 ms; bulbocavernosus reflex latencies ranged from 18.2 to 20.2 ms. The low location of the conus medullaris accounts for the shortening of the monosynaptic H reflex and for a part of the shortening of the polysynaptic bulbocavernosus reflex, anoxia of the conus being probably another important factor. In the absence of previous description of alternative pathology accountable for such a shortening, our observations suggest that shortened sacral reflex latencies might be specific of the tethered cord syndrome.

Female↗
PubMed1993

Relative contributions of cardiopulmonary and sinoaortic baroreflexes in causing sympathetic activation in the human skeletal muscle circulation during orthostatic stress.

The aim of this study was to reexamine the hypothesis that cardiopulmonary baroreflexes are more important than sinoaortic baroreflexes in causing vasoconstriction in the skeletal muscle circulation during orthostatic stress. We recorded muscle sympathetic nerve activity (MSNA) with microelectrodes in the peroneal nerve (and forearm blood flow with venous occlusion plethysmography) in normal subjects (innervated ventricles) and in heart transplant recipients (denervated ventricles) during graded lower body negative pressure (LBNP) performed alone and in combination with intravenous infusion of phenylephrine, which was titrated to eliminate the orthostatically induced fall in blood pressure and thus the unloading of both carotid and aortic baroreceptors. The principal new findings are as follows: (1) The increases in both MSNA and forearm vascular resistance during multiple levels of LBNP were not attenuated by heart transplantation, which causes ventricular but not sinoaortic deafferentation. (2) In heart transplant recipients, a small increase in MSNA during mild LBNP was dependent on a decrease in arterial pressure, but in normal subjects, a similar increase in MSNA occurred in the absence of any detectable decrease in the aortic pressure stimulus to the sinoaortic baroreceptors. (3) In normal subjects, the large increase in MSNA during a high level of LBNP was dependent on a decrease in arterial pressure and could be dissociated from the decrease in central venous pressure. Taken together, the findings strongly suggest that sinoaortic baroreflexes are much more important and ventricular baroreflexes are much less important than previously thought in causing reflex sympathetic activation and vasoconstriction in the human skeletal muscle circulation during orthostatic stress.

Female↗
PubMed1993

Quality assessment and improvement in group psychotherapy.

OBJECTIVE: The authors sought a practical means of monitoring and evaluating group psychotherapy, using existing clinical resources, for purposes of quality improvement and education on a large general hospital psychiatric service. METHOD: Monitoring indicators were developed which addressed 1) the integration of group psychotherapy into treatment planning and 2) the competence and technique of group psychotherapists. The second indicator was assessed by skilled observers using a newly constructed Group Psychotherapy Rating Scale in direct observation of group psychotherapy sessions. The rating scale was examined for interrater reliability and, as a measure of construct validity, for its ability to distinguish the performance of professional staff therapists from that of trainees. RESULTS: The indicators provided useful monitors of the use and quality of group psychotherapy. The rating scale had satisfactory interrater reliability and construct validity. The immediate constructive educational critique given by the observers of the therapy groups was highly valued by group therapists. CONCLUSIONS: The monitoring and evaluation program proved to be a practical, positive, and inexpensive means of assuring and improving the quality of group psychotherapy in a clinical setting.

Humans↗
PubMed1992

Evaluation of somatic and autonomic small fibers neuropathy in diabetes.

The relationship between somatic and autonomic neuropathy was assessed in the feet of 30 diabetic patients. Somatic small fiber function was evaluated by the thermal threshold test for cold (A delta fibers) and warmth (C fibers). Telethermography and transcutaneous oxygen tension were used to investigate the autonomic control of peripheral circulation. Autonomic neuropathy caused the opening of arteriovenous anastomosis, which was revealed through an elevation of the feet's temperature and a low transcutaneous oxygen tension. The association of the opening of the arteriovenous anastomosis and the perturbation of the thermal threshold test established a relationship between the dysfunction of the autonomic and the somatic fibers.

Adolescent↗
PubMed1992

Continuous measurement of left ventricular performance during and after maximal isometric deadlift exercise.

BACKGROUND: Isometric exercise produces a reflex increase in arterial blood pressure that is proportional to the intensity and mass of muscle used during contraction. Little is known about the transient effects of heavy weight lifting on left ventricular performance. In this study, we measured continuous changes in left ventricular performance during maximal large-muscle isometric exercise using the standing deadlift position. METHODS AND RESULTS: Ten healthy young men performed serial deadlifts at 50% of maximal voluntary effort for 90 seconds and 100% of maximal effort for 30 seconds. Echocardiographic imaging (apical four-chamber view), arterial blood pressure (brachial artery catheter), and electrocardiographic monitoring were recorded throughout the deadlift and for 30 seconds of recovery. Aortic flow velocity was also monitored during a separate series of deadlifts. During 100% maximal deadlift, mean arterial pressure increased from 108 +/- 4 to 164 +/- 6 mm Hg. Left ventricular ejection fraction declined initially (from 57 +/- 2% to 49 +/- 3%) at 15 seconds into the lift and recovered (56 +/- 1%) due to significant increases in end-diastolic volume (104 +/- 11 ml to 132 +/- 16 ml) by the end of the lift. The peak systolic pressure/end-systolic volume ratio did not change during the deadlift. After cessation of the deadlift, mean arterial pressure declined precipitously (to 88 +/- 4 mm Hg) within 5 seconds and gradually returned to baseline after 30 seconds. Left ventricular performance indexes all increased significantly during the recovery phase (ejection fraction to 68 +/- 3%, peak systolic pressure/end-systolic volume ratio to 5.9 +/- 0.9). Findings were qualitatively similar for the 50% deadlift. CONCLUSIONS: During an intense isometric deadlift, left ventricular performance declines initially but is restored by the Frank-Starling mechanism. Upon release of the deadlift, increased left ventricular performance develops in conjunction with a rapid decrease in arterial pressure. The combined effects of increased wall stress during the lift phase and enhanced contractility during the release phase probably contribute to left ventricular hypertrophy associated with repetitive weight training.

Adult↗
PubMed1991

Forearm vascular resistance increases during static exercise in heart transplant recipients.

In heart transplant recipients but not in normal humans, total peripheral vascular resistance increases during static exercise. To determine whether this augmented vasoconstriction limits the vasodilation normally seen in the nonexercising forearm, we measured arterial pressure, heart rate, and forearm blood flow during 30% maximal static handgrip in 9 heart transplant recipients and 10 control subjects. Handgrip evoked comparable increases in mean arterial pressure in the transplant recipients and control subjects (+19 +/- 2 vs. +20 +/- 2 mmHg). Heart rates increased by 14 +/- 3 beats/min in the control subjects but did not change in the transplant recipients. Directionally opposite patterns of forearm vascular resistance were observed in the two groups. In the control subjects, forearm resistance fell during handgrip (-8.8 +/- 1.9 units, P less than 0.05). In contrast, in the transplant recipients, forearm resistance rose during this intervention (+9.0 +/- 2.9 units, P less than 0.05). Thus the vasodilation that normally occurs in the nonexercising forearm during static handgrip is reversed in heart transplant recipients. Vasoconstriction in the forearm contributes to the increase in total peripheral resistance that occurs during static exercise in these individuals.

Adult↗