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PubMed1998

Surgical treatment of concomitant chronic ankle instability and longitudinal rupture of the peroneus brevis tendon.

Chronic lateral ankle instability can be associated with a longitudinal rupture of the peroneus brevis tendon. Patients with these problems have atypical posterolateral or retromalleolar pain, as well as clinical signs of ligamentous instability. This injury is frequently concomitant with lateral ligament injuries and the injury mechanism is similar; however, the tendon rupture is often missed. Laxity or insufficiency of the superior peroneal retinaculum allows the anterior part of the peroneus brevis tendon to ride upon the sharp posterior fibular edge, resulting in a longitudinal rupture of the tendon. We report on the results after surgical treatment in nine patients (10 ankles) with combined instability of the lateral ankle ligaments and longitudinal rupture of the peroneus brevis tendon. All these patients underwent surgical repair of the peroneus tendon, reconstruction of the superior peroneal retinaculum, removal of the sharp posterior edge of the fibula and correction of the ligamentous instability of the anterior talofibular and calcaneofibular ligaments. One constant finding at surgery was a longitudinal intratendineal rupture of the peroneus brevis tendon combined with insufficiency of the superior peroneal retinaculum and insufficiency of the lateral ligaments. At follow-up 3 (2-5) years post-operatively, the functional results were excellent or good in nine ankles and fair in one. All the patients with excellent or good results had resumed their preinjury activity level. We conclude that this lesion should be suspected in patients with lateral ligamentous instability, combined with retromalleolar pain. In these cases, it is important to address both the tendon rupture and the ligamentous insufficiency.

Adolescent↗
PubMed1982

Effect of frequency of growth hormone administration on longitudinal bone growth and body weight in hypophysectomized rats.

The effect of frequency of growth hormone (GH) administration on longitudinal bone growth and body weight was studied in hypophysectomized rats. Replacement therapy with 3 different doses of human GH [(hGH) Crescormone] was started 10-14 days after hypophysectomy and was continued for 5 days. Longitudinal bone growth, as measured by the tetracycline method, and body weight were determined during the injection period. With a daily replacement dose of 128 micrograms of hGH body weight gain and longitudinal bone growth were significantly higher when the hormone was injected 4 and 8 times per day compared with animals receiving the hormone in one daily injection. When the dose of hGH was 32 or 8 micrograms per day, longitudinal bone growth and body weight gain were more pronounced in animals receiving the hormone 2 and 4 times per day compared with animals receiving the hormone one or 8 times per day. The results of the present study demonstrate that the frequency of GH administration influence body growth. The findings suggest that the secretory pattern of GH influence the growth rate under in vivo condition.

Animals↗
PubMed1988

Different effects of neuropeptide Y on electrically induced contractions in the longitudinal and circular smooth muscle layers of the female rabbit urethra.

The effects of neuropeptide Y (NPY) on preparations of isolated longitudinal and circular smooth muscle from rabbit urethra were studied. In both types of muscle, electrically induced contractions and relaxations could be abolished by tetrodotoxin, (TTX). In the longitudinal muscle preparations the contraction was slightly reduced by prazosin, but markedly reduced by scopolamine and NPY. The NPY effect was not influenced by pretreatment with rauwolscine. Pretreatment with NPY had no effect on contractions induced by noradrenaline (NA) or carbachol and the peptide did not relax preparations contracted by these agents. In circular muscle an initial, fast response, not sensitive to prazosin or scopolamine was occasionally observed following electrical stimulation. A slow contraction component was regularly seen; this response was abolished by prazosin. Neuropeptide Y did not influence any of these responses. The preparations were concentration-dependently contracted by NA, whereas carbachol had no effect. Pretreatment with NPY did not affect contractions induced by NA, nor did the peptide relax NA-contracted preparations. In neither longitudinal nor circular muscle strips did NPY affect the electrically induced TTX sensitive relaxation of NA-contracted preparations. The results suggest that in the rabbit urethra NPY reduces contractions in the longitudinal muscle layer by selectively inhibiting the release of acetylcholine from cholinergic nerves. Neuropeptide Y did not appear to have any significant postjunctional effects nor to interfere with the release, or effects of NA or other transmitter agents. The physiological importance of the urethral effects of NPY remains to be established.

Animals↗
PubMed1969

The longitudinal tissue impedance of the smooth muscle of guinea-pig taenia coli.

1. The absolute value of the tissue impedance of the guinea-pig taenia coli was measured in the longitudinal direction in air at 36 degrees C. The relation between the tissue impedance and the separation of the recording electrodes indicated that the tissue has cable-like properties. The frequency dependence of the impedance, observed at various distances from the current supplying electrode, showed that the tissue has a capacity component in the longitudinal direction.2. The tissue impedance in the longitudinal direction was also measured while the tissue was suspended in a narrow tube at 25-28 degrees C. The tissue impedance was calculated on the basis of the difference between the total impedance in Krebs solution and that in Krebs solution containing half the normal Na concentration, knowing the specific resistance of both solutions.3. The impedance per unit volume of the tissue was 370 Omega cm at 10 c/s and 190 Omega cm at 10 kc/s; at these frequencies the impedance was nearly independent of current frequency. The difference between the impedances (370 - 190 = 180 Omega cm) was taken to be the impedance of the junctions between cells. The possibility of slightly lower values for the actual tissue impedance was discussed. The capacity located at or near the junction was calculated to be 1-3 muF/cm, the time constant of the junctional membrane being about 0.5 msec.4. Ca ions (0-12.5 mM) and adrenaline (2 x 10(-7) g/ml.) had no measurable effect on the longitudinal impedance within 10-15 min. In hyperosmotic solution of twice osmolarity (by adding sucrose), the tissue impedance was increased by about 50%. When the tissue was immersed in sucrose solution containing no ions, the impedance gradually increased up to nearly 10 times in the course of 1 hr.

Animals↗
PubMed1975

Some differences in contractile responses of isolated longitudinal and circular muscle from the guinea-pig stomach.

The mechanical and electrical properties of the longitudinal (fundus and corpus) and circular (antrum) muscle fibres of the guinea-pig stomach were investigated. 1. In the longitudinal but not in the circular muscle isotonic K Krebs and Na-free (sucrose) Krebs solutions produced a contracture with a tonic component. The different mechanical responses were not accompanied by different membrane responses. Verapamil abolished both phasic and tonic components of K-induced contracture. 2. During the tonic response of the K-induced contracture, repolarization of the membrane by current pulses relaxed the tissue; after cessation of the current pulse, rebound contracture occurred. In the circular muscle, the Q10 value for the rate of relaxation induced by inward current pulse was 3-1 and for the development of rebound contracture was 2-4. 3. After the tissue had been immersed in Ca-free isotonic K Krebs solution, application of Ca produced a large contracture in the longitudinal muscle, but contracture in the circular muscle was small or absent. However, the amplitude of subsequent carbachol-induced contracture in the above solution was enlarged in proportion to the durations of Ca treatment in both tissues. 4. Direct tetanic electrical stimulation could produce tension in both tissues. With low frequency of stimulation (0-1 Hz) a positive staircase was observed in the circular but not in the longitudinal muscle. 5. It is concluded from these results that topical differences of the motility in the stomach may be due not only to the activity of nervous elements, but also to differences in the properties of the muscle fibres themselves.

Animals↗
PubMed1981

Longitudinal spread of adaptation in the rods of the frog's retina.

1. The stimulus-response function of the red rods in the retina of the common frog (Rana temporaria) was determined in different adaptational states by measuring aspartate-isolated receptor responses. 2. Flash stimuli, background adaptations and bleaches were delivered through the same optical channel forming an oblique light-beam striking the receptor side of the isolated and flat-mounted retina at an angle of 10 degrees. 3. When the light was blue-green and optimally polarized the absorbance of the receptor layer was about 2, from which follows that 70-80% of the light was absorbed in the distal third of the rod outer segments, i.e. the exposure was local. Homogeneous exposures of the whole rod outer segments were obtained with orange and red lights. 4. Combinations of homogeneous and local stimuli with homogeneous and local adaptations were used to investigate the longitudinal spread of background, intermediate and opsin adaptation, i.e. the sensitivity-reducing effect of a background light, and the transient and permanent sensitivity losses following a bleach isomerizing 3.5-26% (usually 10%) of the rhodopsin in the retina. 5. The results obtained were related to predictions based both on the assumption that the adaptation effects spread longitudinally within the rod outer segments and the assumption that they are strictly confined to the disks absorbing the adapting lights. 6. These comparisons reveal that all three types of adaptation spread longitudinally. It is for instance clear that the sensitivity loss observed with homogeneous stimuli and local adaptation (as compared to homogeneous adaptation) is larger than that predicted by the non-spreading hypothesis. 7. The longitudinal spread of background adaptation is largely finished within 10 sec after turning on the background light, while an efficient spread of the intermediate adaptation effect may require minutes. 8. A background light decreasing the sensitivity by about one log unit decreases the time from flash to response maximum from 5 to 1 sec (small responses). Corresponding opsin adaptation effects are accompanied by less dramatic changes in response kinetics. 9. Independent of adaptation type - homogeneous or local, background, intermediate or opsin - it was found that local stimuli are less efficient that homogeneous stimuli in light-adapted retinae. This effect can be explained assuming that the sensitivity-reducing effects are pronounced in the distal than in the proximal parts of the rod outer segments. 10. The opsin adaptation effect following 10% local bleaches decreases the sensitivity to both homogeneous and local stimuli 2-3 times more than corresponding homogeneous bleaches. This means that the strength of the opsin effect is not related to the average percentage bleached but to the fraction bleached in the distal part of the rod, or generally to the fraction bleached in the most affected region. 11...

Adaptation, Ocular↗
PubMed2005

Magnetic confinement of electron and photon radiotherapy dose: a Monte Carlo simulation with a nonuniform longitudinal magnetic field.

It recently has been shown experimentally that the focusing provided by a longitudinal nonuniform high magnetic field can significantly improve electron beam dose profiles. This could permit precise targeting of tumors near critical areas and minimize the radiation dose to surrounding healthy tissue. The experimental results together with Monte Carlo simulations suggest that the magnetic confinement of electron radiotherapy beams may provide an alternative to proton or heavy ion radiation therapy in some cases. In the present work, the external magnetic field capability of the Monte Carlo code PENELOPE was utilized by providing a subroutine that modeled the actual field produced by the solenoid magnet used in the experimental studies. The magnetic field in our simulation covered the region from the vacuum exit window to the phantom including surrounding air. In a longitudinal nonuniform magnetic field, it is observed that the electron dose can be focused in both the transverse and longitudinal directions. The measured dose profiles of the electron beam are generally reproduced in the Monte Carlo simulations to within a few percent in the region of interest provided that the geometry and the energy of the incident electron beam are accurately known. Comparisons for the photon beam dose profiles with and without the magnetic field are also made. The experimental results are qualitatively reproduced in the simulation. Our simulation shows that the excessive dose at the beam entrance is due to the magnetic field trapping and focusing scattered secondary electrons that were produced in the air by the incident photon beam. The simulations also show that the electron dose profile can be manipulated by the appropriate control of the beam energy together with the strength and displacement of the longitudinal magnetic field.

Algorithms↗
PubMed1994

Longitudinal resolution in volumetric x-ray computerized tomography--analytical comparison between conventional and helical computerized tomography.

The primary advantage of helical computerized tomography (CT) is the capability of scanning a complete anatomical volume in a single breath hold. Due to the table motion and subsequent interpolation process, the slice sensitivity profile (SSP) in helical CT is worse than the response function of the detector array. In this paper, image longitudinal resolution in volumetric x-ray CT is analytically characterized, and a comparison made between conventional and helical CT. First, the SSPs are derived for both conventional and helical CT with the half-scan interpolation method under the condition that the table increment and detector collimation are the same. Then, the corresponding transfer functions are obtained for bandwidth determination, which directly describe the spatial resolution. Both one-tenth-cutoff and mean-square-root measures are used to quantify the bandwidth. Although it appears that broadening the SSP in helical CT could adversely affect longitudinal resolution, it is proved that for a given x-ray dose, helical CT allows substantially better longitudinal resolution than conventional CT due to its inherent retrospective reconstruction capability. To make full use of the potential of helical CT scan data, it is recommended that about five slices be reconstructed per table increment. Helical CT is superior in applications requiring a high longitudinal resolution.

Algorithms↗
PubMed1990

Transoesophageal echocardiography in the longitudinal axis: correlation between anatomy and images and its clinical implications.

Transoesophageal echocardiographic imaging in the longitudinal axis is a recent addition to the non-invasive evaluation of congenital and acquired heart disease. The technique provides unique images of intracardiac anatomy but their interpretation remains difficult. A heart specimen was therefore cut according to the echocardiographic imaging planes to elucidate the morphological details. The results suggested that longitudinal transoesophageal imaging complements the transverse axis approach. It gave new imaging information on the right ventricular outflow tract and the pulmonary trunk, the atrioventricular valves, the interventricular septum, the cardiac apex, and the thoracic aorta. In particular, it showed the entire length of the right ventricular outflow tract. When longitudinal imaging was used in combination with transverse imaging almost all the thoracic aorta could be examined. Imaging in the longitudinal axis may also allow better assessment of the mechanisms of atrioventricular valve regurgitation.

Aorta, Thoracic↗
PubMed2005

A longitudinal study of sentence comprehension difficulty in primary progressive aphasia.

CONTEXT: Patients with primary progressive aphasia have sentence comprehension difficulty, but the longitudinal course of this deficit has not been investigated. OBJECTIVE: To determine how grammatical, single word meaning, and working memory factors contribute to longitudinal decline of sentence comprehension in primary progressive aphasia. We hypothesised partially distinct patterns of sentence comprehension difficulty in subgroups of patients with progressive non-fluent aphasia (PNFA) and semantic dementia (SD). DESIGN: Cohort. SETTING: Institutional out patient referral centre. PATIENTS: PNFA (n = 14), SD (n = 10). MAIN OUTCOME MEASURE: Sentence comprehension accuracy. RESULTS: PNFA patients were significantly impaired at understanding grammatically complex sentences when first seen, and this was more evident than impairment of their comprehension of grammatically simple sentences (p<0.05). Comprehension of grammatically complex sentences correlated with their working memory deficit at presentation (p<0.05). PNFA patients showed modest decline over time in grammatical comprehension. In SD, comprehension of grammatically complex sentences was not more impaired than comprehension of grammatically simple sentences when first seen, but these patients demonstrated a significant longitudinal decline in understanding grammatically complex sentences (p<0.05). Cox regression analyses showed that a deficit in single word meaning contributes to the progressive impairment for grammatically complex sentences in SD (p<0.05), but working memory does not contribute to longitudinal decline in PNFA. CONCLUSION: Patients with PNFA and SD have sentence comprehension difficulty, but distinct factors contribute to this impairment during the course of their disease.

Aged↗
PubMed1987

Ossification of the posterior longitudinal ligament: a clinico-radiological study of 74 cases.

A clinico-radiological analysis of 74 cases of ossification of the posterior longitudinal ligament is reported. Eighteen cases (24%) were asymptomatic or only had neck or shoulder pain; 16 cases (22%) showed signs of radiculopathy, and the remaining 40 cases (54%) had myelopathy. Ossification of the posterior longitudinal ligament developed most frequently at C5, and was rare in thoracic and lumbar regions. Ossification of the posterior longitudinal ligament led to stenosis of the spinal canal; more marked stenosis caused clinical myelopathy. The data showed that 30% of stenosis caused by ossification of the posterior longitudinal ligament was critical for the production of myelopathy.

Adult↗
PubMed1987

The sensitivity of the longitudinal and circular muscle layers of the rat's myometrium to oxytocin in vitro during pregnancy.

To test the hypothesis that binding site regulation is the primary process controlling the responsiveness of the rat's myometrium to oxytocin during pregnancy, I have studied the effects of oxytocin on longitudinal and circular strips of myometrium in vitro throughout pregnancy. Longitudinal muscle was as sensitive on day 10 of pregnancy (EC50 = 1.6 nM) as it was at term (EC50 = 1.3 nM) and there was no significant change in the mean maximal force developed in response to the hormone (2.1 +/- 0.9 vs. 1.5 +/- 0.3 N cm-2). Circular muscle on the other hand was essentially refractory to the hormone until day 21 of pregnancy at which time its sensitivity and the maximum response were similar to those of longitudinal muscle. These results indicated that regulation of oxytocin sensitivity in the two muscle layers was temporally different, and they suggested different mechanisms. The effect of oxytocin on longitudinal muscle was not compatible with the hypothesis that changes in binding site number regulate the responsiveness of the tissue, whereas the effect on circular muscle was.

Animals↗
PubMed2003

Longitudinal and circumferential spike patches in the canine small intestine in vivo.

In an open-abdominal anesthetized and fasted canine model of the intact small intestine, the presence, location, shape, and frequency of spike patches were investigated. Recordings were performed with a 240-electrode array (24 x 10, 2-mm interelectrode distance) from several sites sequentially, spanning the whole length of the small intestine. All 240 electrograms were recorded simultaneously during periods of 5 min and were analyzed to reconstruct the origin and propagation of individual spikes. At every level in the small intestine, spikes propagated in all directions before stopping abruptly, thereby activating a circumscribed area termed a "patch." Two types of spikes were found: longitudinal spikes, which propagated predominantly in the longitudinal direction and occurred most often in the duodenum, and a second type, circumferential spikes, which propagated predominantly in the circular direction and occurred much more frequently in the jejunum and ileum. Circumferential spikes conducted faster than longitudinal spikes (17 +/- 6 and 7 +/- 2 cm/s, respectively; P < 0.001). Circumferential spikes originated in >90% of all cases from the antimesenteric border, whereas longitudinal spikes were initiated all around the circumference of the intestinal tube. Finally, the spatial sequence of spike patches after the slow wave was very irregular in the upper part of the intestine but much more regular in the lower part. In conclusion, spikes and spike patches occur throughout the small intestine, whereas their type, sites of origin, extent of propagation, and frequencies of occurrence differ along the length of the small intestine, suggesting differences in local patterns of motility.

Action Potentials↗
PubMed1998

Regulation of excitatory neural input to longitudinal intestinal muscle by myenteric interneurons.

The circuit of myenteric interneurons that regulate excitatory input to longitudinal colonic muscle was identified using dispersed ganglia and longitudinal muscle strips with adherent myenteric plexus from rat distal colon. The preparations enabled measurement of neurotransmitter release from interneurons and/or excitatory motoneurons innervating longitudinal muscle. 1, 1-Dimethyl-4-phenylpiperizinium (DMPP) and somatostatin were used to activate myenteric neurons in dispersed ganglia and muscle strips, respectively. DMPP-stimulated vasoactive intestinal peptide (VIP) release in dispersed ganglia was inhibited by [Met]enkephalin and bicuculline and augmented by naloxone and GABA, implying that inhibitory opioid and stimulatory GABA neurons regulate the activity of VIP interneurons. In muscle strips, VIP stimulated basal and augmented somatostatin-induced substance P (SP) release; the somatostatin-induced increase in SP release was inhibited by VIP-(10-28) and NG-nitro-L-arginine, implying that excitatory VIP neurons regulate tachykinin motoneurons innervating longitudinal muscle. Somatostatin inhibited [Met]enkephalin and stimulated VIP release; basal and somatostatin-stimulated VIP release were inhibited by [Met]enkephalin and bicuculline and augmented by naloxone and GABA, implying that inhibitory pathways linking somatostatin, opioid, and GABA neurons regulate VIP interneurons, which in turn regulate tachykinin and probably cholinergic motoneurons.

Animals↗
PubMed2002

Effects of longitudinal stretch on VSM tone and distensibility of muscular conduit arteries.

With progressing age, large arteries diminish their longitudinal stretch, which in extreme cases results in tortuosity. Increased age is also associated with loss of vessel distensibility. We measured pressure-diameter curves from muscular porcine carotid arteries ex vivo at different longitudinal stretch ratios (lambda(z) = 1.4 and 1.8) and under different vascular smooth muscle (VSM) conditions (fully relaxed, normal VSM tone, and maximally contracted). Distensibility was found to be halved by decreasing longitudinal stretch from lambda(z) = 1.8 to 1.4 at physiological pressures. This counterintuitive observation is possible because highly nonlinear elastic modulus of the artery and anisotropic properties. Furthermore, a significantly larger basal VSM contraction was observed at lambda(z) = 1.8 than 1.4, although this was clearly not related to a myogenic response during inflation. This dependence of VSM tone to longitudinal stretch may have possible implications on the functional characteristics of the arterial wall.

Animals↗
PubMed1975

Longitudinal contractions in the duodenum: their fluid-mechanical function.

The hypothesis examined was that contractions of the longitudinal muscle layer occurin the duodenum which are independent of those of the circular muscle layer and that they induce flow of duodenal contents. A segment of opossum duodenum isolated in vitro was marked and photographed during periods of longitudinal muscle contraction, when the circular muscle layer appeared inactive. The prequency of longitudinal oscillation of the marked points was 20.5 cycles/min. The longitudinal displacement wave spread caudad with an average velocity of 3.27 cm/s. Frequency and velocity of electrical slow waves were determined in similiar duodenal segments. Slow-wave frquencywas 18.9 cycles/min. In a two-dimensional mechanical model, flow induced by simulatedlongitudinal muscle layer appear to be driven by the electrical slow waves of the duodenum. They are capable of inducing a pattern of flow in which ocntents flow betweenthe core and the periphery of the intestinal conduit.

Animals↗
PubMed1989

Frequency of spontaneous contractions in longitudinal and transverse bladder strips.

The frequency components of spontaneous contractility of rabbit bladder strips were examined with respect to their orientation and position. Spectra of longitudinal and transverse strips of bladder were studied in vitro in consecutively dissected segments from the same bladder. The frequency characteristics of these strips were characterized at rest and also with incremental extension to 125% of original length. Results show that transverse and longitudinal strips of bladder muscle undergo continuous spontaneous contractions in the frequency range of 0.01-0.25 Hz. The amplitude of the spontaneous contractions is not dependent on the amount of resting tension in either longitudinal or transverse strips. Longitudinal strips have a higher frequency of spontaneous variations of tension compared with the transverse strips. The amplitude of transverse strips is lowest at the base of the bladder, and the frequency components of activity increases in magnitude toward the bladder dome. Extension of transverse strips shows the generation of frequency peaks of tissues located at the middle of the bladder having a significantly lower rate of relaxation than the proximal or distal strips. Spontaneous contractility of the bladder indicates the presence of a potentially significant parameter that must be considered when tissue response to mechanical, electrical, or pharmacological stimulation is interpreted.

Animals↗
PubMed2001

Epileptiform discharges with in-vivo-like features in slices of rat piriform cortex with longitudinal association fibers.

Brain slices serve as useful models for the investigation of epilepsy. However, the preparation of brain slices disrupts circuitry and severs axons, thus complicating efforts to relate epileptiform activity in vitro to seizure activity in vivo. This issue is relevant to studies in transverse slices of the piriform cortex (PC), the preparation of which disrupts extensive rostrocaudal fiber systems. In these slices, epileptiform discharges propagate slowly and in a wavelike manner, whereas such discharges in vivo propagate more rapidly and jump abruptly between layers. The objective of the present study was to identify fiber systems responsible for these differences. PC slices were prepared by cutting along three different nearly orthogonal planes (transverse, parasagittal, and longitudinal), and epileptiform discharges were imaged with a voltage-sensitive fluorescent dye. Interictal-like epileptiform activity was enabled by either a kindling-like induction process or disinhibition with bicuculline. The pattern of discharge onset was very similar in slices cut in different planes. As described previously in transverse PC slices, discharges were initiated in the endopiriform nucleus (En) and adjoining regions in a two-stage process, starting with low-amplitude "plateau activity" at one site and leading to an accelerating depolarization and discharge onset at another nearby site. The similar pattern of onset in slices of various orientations indicates that the local circuitry and neuronal properties in and around the En, rather than long-range fibers, assume dominant roles in the initiation of epileptiform activity. Subtle variations in the onset site indicate that interneurons can fine tune the site of discharge onset. In contrast to the mode of onset, discharge propagation showed striking variations. In longitudinal slices, where rostrocaudal association fibers are best preserved, discharge propagation resembled in vivo seizure activity in the following respects: propagation was as rapid as in vivo and about two to three times faster than in other slices; discharges jumped abruptly between the En and PC; and discharges had large amplitudes in superficial layers of the PC. Cuts in longitudinal slices that partially separated the PC from the En eliminated these unique features. These results help clarify why epileptiform activity differs between in vitro and in vivo experiments and suggest that rostrocaudal pyramidal cell association fibers play a major role in the propagation of discharges in the intact brain. The longitudinal PC slice, which best preserves these fibers, is ideally suited for the study their role.

Animals↗