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PubMed2002

Role of the longitudinal smooth muscle coat in the ileal motile activity: evidence of ileo-ileal inhibitory reflex.

BACKGROUND: All gut movements are claimed to be activated essentially by the concentric contraction of the circular muscle, moving the chyme aborally. The role of the longitudinal smooth muscle of the small intestine in gut motility is poorly understood; this point was investigated in the current study. METHODS: The abdomens of 14 crossbreed dogs (eight dogs, six bitches) were opened. A segment of the small intestine was distended by a balloon in increments of 2 mL of saline, and the pressure and electrical activity were recorded proximally and distally to the balloon. The gut wall around the balloon was anesthetized and the test was repeated. The longitudinal muscle coat of the small intestine segment was then excised, and the pressure response and electrical activity were recorded on ileal distension. RESULTS: Two milliliter ileal distension produced pressure decrease (P < 0.05) proximally and distally to the balloon and caused balloon movement. Four, 6 and 8 mL distension effected similar pressure response, while 10 mL showed no response. Electrical waves were recorded from the three electrodes applied to the ileal segment. Upon ileal distension, electrical activity increased over the distended area, with no activity proximally and distally to it. Balloon distension of the anesthetized ileal segment produced no pressure response or electrical activity. After longitudinal myectomy, no electrical activity was recorded at rest or upon ileal distension, and the balloon did not move. CONCLUSION: Ileal distension initiated circular muscle contraction only in the presence of the overlying longitudinal muscle, which appears to transmit the electrical activity to the circular muscle upon ileal distension. Ileal contraction is suggested to initiate ileal hypotonia in the proximal and distal ileal segments mediated through an 'ileo-ileal inhibitory reflex' that leads to aboral progress of the proximally and distally located chyme.

Animals↗
PubMed1998

The growth of the human embryo. A longitudinal biometric assessment from 7 to 12 weeks of gestation.

OBJECTIVES: Longitudinal studies of multiple parameters in the first trimester for assessment of embryonic growth are lacking. This study's aim was to register changes in growth over time, by taking several measurements of embryos on successive occasions and evaluating these changes by longitudinal analysis. DESIGN: This prospective longitudinal study describes the normal embryonic growth in vivo. Inclusion criteria were non-smoking women with single uneventful pregnancies, regular menstrual periods (28-30 days) and no hormone therapy in the 3 months prior to the pregnancy. Exclusion criteria were pregnancy complications such as diabetes, pre-eclampsia, delivery of preterm or growth-restricted infants. Of 36 recruited pregnant women, 29 met these criteria. Each pregnancy was examined five times between 7 and 12 weeks of gestation. This resulted in a two-level data set, where level 1 consisted of the observations and level 2 consisted of the individuals. The longitudinal data were analyzed with a software package specially created for multilevel analysis. RESULTS: The growth of the biparietal diameter (BPD), occipitofrontal diameter (OFD), mean abdominal diameter (MAD), chorionic cavity diameter and amniotic cavity diameter was constant; the growth of the crown-rump length (CRL) and the yolk sac diameter was not constant. Variation in the data sets was mainly caused by variation between the embryos/fetuses. CONCLUSIONS: The measured parameters except for the yolk sac showed a high degree of uniformity with virtually the same growth velocities. The yolk sac demonstrated uniform growth until week 10 only. Differences between the gestational age based on the last menstrual period and the true gestational age, and/or differences in the early growth of the embryos before the start of the study at 7 weeks, may have contributed to the variation between the individuals.

Adult↗
PubMed2003

A new non-invasive ultrasonic method for simultaneous measurements of longitudinal and radial arterial wall movements: first in vivo trial.

During recent years, the radial movement of the arterial wall has been extensively studied, and measurements of the radial movement are now an important tool in cardiovascular research for characterizing the mechanical properties of the arterial wall. In contrast, the longitudinal movement of vessels has gained little or no attention as it has been presumed that this movement is negligible. With modern high-resolution ultrasound, it can, however, be seen that the intima-media complex of the arterial wall moves not only in the radial direction, but also in the longitudinal direction during pulse-wave propagation. This paper describes a new non-invasive ultrasonic method that is able to measure simultaneously two dimensionally arterial vessel wall movements. The method is demonstrated in a limited in vivo trial. Results from the in vivo trial show that, apart from the well-known radial movement, there is a distinct longitudinal movement in the human common carotid artery with, in this case, the intima-media complex moving substantially as compared with the region of the tunica adventitia. Two-dimensional evaluation of the vessel-wall movements, taking not only the radial movement, but also the longitudinal movement into account, may provide novel information of importance in the evaluation of vessel-wall function.

Carotid Artery, Common↗
PubMed2000

Anxiety and depression after spinal cord injury: a longitudinal analysis.

OBJECTIVE: To examine the prevalence of anxiety and depression longitudinally in a sample of patients with a spinal cord injury (SCI). DESIGN: A prospective, longitudinal, multiple wave panel design with measures taken on 14 observational periods ranging from initial contact in the acute stages of hospitalization to 2 years' postdischarge to the community. SETTING: The National Spinal Injuries Centre, Stoke Mandeville Hospital, Aylesbury, UK, and the general community. PARTICIPANTS: The cohort consisted of 104 patients with traumatic SCI (19 women, 85 men), although the numbers assessed at each interval ranged from 5 to 85. MAIN OUTCOME MEASURES: Measures included the Beck Depression Inventory, the Beck Hopelessness scale, the State Anxiety Inventory, the functional independence measure, and the Social Support Questionnaire. RESULTS: When examined longitudinally, the data illustrate a consistent pattern of results across measures, with scores highest in the acute phase of the injury and during the months leading up to discharge. CONCLUSION: The numbers of persons scoring above clinical cut-off scores for anxiety and depression highlight the need to continue to ensure that appropriate psychological care is available within SCI rehabilitation settings. Moreover, the nature of the longitudinal results provides an indicator of subtle changes in anxiety and depression over time.

Adolescent↗
PubMed1999

The effect of 'non-critical' (<50%) stenosis on vein graft longitudinal resistance and impedance.

OBJECTIVE: vein graft stenoses <50% cause minimal flow impairment, velocity elevation, or symptomatology and are therefore usually assumed to be "non-critical". The purpose of this study was to assess the effect of <50% vein graft stenosis on vein graft longitudinal impedance, as elevated impedance has been found to correlate with clinical graft failure. METHODS: eight segments of non-reversed cryopreserved vein (mean length 23+/-1 cm; mean outer diameter 4.7+/-0.2 mm) were saline-perfused in vitro utilising a variable pulsatile perfusion pump, Windkessel, and clamp resistor simulating the haemodynamic conditions of arterial bypass. Proximal (Pprox) and distal (Pdist) pressure were continuously measured by fluid-filled catheter transduction, and flow (Q) by ultrasonic transit-time flowmetry. Waveforms were digitally recorded at 200 Hz at pulse rates ranging from 60-180 b.p.m. with mean flow (Q) of 154 ml/min and mean proximal pressure (Pprox) of 100 mmHg (max/min 120/90). Graded mid-graft stenoses of <50% were created using an inflatable vascular occluder and measured by the corresponding changes in mean pressure gradient (DeltaP=Pprox-Pdist) and Q (%stenosis=1-{DeltaPbaselineQstenosis/Delta PstenosisQbaseline}1/4). Vein graft longitudinal resistance (RL) was calculated as DeltaP/Q. After Fourier transformation, vein graft longitudinal impedance (ZL) was calculated as DeltaP/Q at each harmonic, with ZL determined by integration over 0-4 Hz. Results are reported as mean+/-S.E.M. RESULTS: the desired levels of pressure and flow were established in all vein segments. Graded inflation of the occluder resulted in vein graft stenosis of 23+/-3% and 39+/-3%. This was accompanied by a mild reduction in Q (12% and 30%) and considerable increases in both RL (180% and 710%) and ZL (140% and 430%). CONCLUSIONS: "non-critical" vein graft stenosis (<50%) causes minimal change in mean flow, but substantial elevations in longitudinal resistance and impedance. The contribution of "non-critical" stenosis to vein graft failure may be under-appreciated.

Blood Vessel Prosthesis↗
PubMed2004

Morphology and urodynamics after longitudinal urethral plate incision in proximal hypospadias repairs: long-term results.

AIM: To determine whether longitudinal neourethra incision disturbs the healing and growth of the neourethra, and to see how it affects the urine flow after proximal hypospadias repairs. SUBJECTS AND METHODS: Nine patients were examined, in whom longitudinal incision had been performed 9 - 15 years earlier, after previous penis lengthening operations. Calibration, urethrography, endoscopy, and urodynamics were carried out in all patients. RESULTS: In all but 1 patient the external meatus had steadily been growing in width, and in 8 out of 9 it was within the normal size range. Urethroscopy showed single hairs growing into the lumen in 3 patients. No scarring was demonstrated in any patient. Saccular dilatation of the neourethra was found in 6 out of 9, urethral stricture was shown in only 1 patient. Peak flow rate was within 2 SD in 5 patients, and below 2 SD in 3. Average flow rate was below 2 SD in 6 patients and in all patients it was markedly low. In the patient with urethral stricture both peak flow rate and average flow rate were well below normal. CONCLUSIONS: Although longitudinal neourethra incision allows for easy and safe closure, longitudinal incision may result in functional meatal stenosis with formation of a wide neourethra. This may be due to disproportional low resistance of the urethral wall, compared with external meatus, to urine flow.

Adolescent↗
PubMed2002

Impaired retention of spatial memory after transection of longitudinally oriented axons of hippocampal CA3 pyramidal cells.

Longitudinally oriented axon collaterals of CA3 pyramidal cells may be critical for integrating distributed information in the hippocampus. To investigate the possible role of this pathway in the retention of spatial memory, we made a single transversely oriented cut through the dorsal CA3 region of each hippocampus. Although the lesion involved <3% of the hippocampal volume, it nonetheless disrupted memory retention in a water maze in preoperatively trained rats. New learning in a different water maze was attenuated. No significant impairment occurred in rats with longitudinally oriented cuts, or in animals with ibotenic acid-induced lesions of similar magnitude. To characterize the effect of a focal lesion on the integrity of longitudinally projecting axons, we stained degenerating cells and fibers in rats with unilateral CA3 transections by using FluoroJade-B. Degenerating terminals were seen across a wide region posterior to the cut, and were present in the strata of areas CA3 and CA1 that are innervated by CA3 pyramidal cells. These results suggest that the integrity of longitudinally oriented, translamellar axons of CA3 pyramidal cells may be necessary for efficient acquisition and retention of spatial memory.

Animals↗
PubMed1995

Agonist-stimulated cyclic ADP ribose. Endogenous modulator of Ca(2+)-induced Ca2+ release in intestinal longitudinal muscle.

We have previously shown that agonist-induced Ca2+ mobilization in intestinal longitudinal muscle is mediated by ryanodine-sensitive, inositol 1,4,5-trisphosphate-insensitive sacroplasmic Ca2+ channels. Ca2+ release via these channels is triggered by agonist-stimulated Ca2+ influx and results in Ca(2+)-induced Ca2+ release. The present study examined whether cyclic ADP-ribose (cADPR) is synthesized in response to stimulation of longitudinal muscle by agonists and modulates the activity of Ca2+ release channels. Cyclic ADPR bound with high affinity to dispersed longitudinal muscle cells (IC50 1.9nM) and induced Ca2+ release (EC50 3.8 nM), increase in [Ca2+]i (EC50 2.0 nM), and contraction (EC50 1.1 nM); cADPR had no effect on circular muscle cells. The effects of cADPR were blocked by ruthenium red, dantrolene, and the specific antagonist, 8-amino-cADPR, and were augmented by caffeine but not affected by heparin. The binding of cADPR and its ability to stimulate Ca2+ release were dependent on the concentration of Ca2+. Cyclic ADPR was capable of stimulating Ca2+ release at subthreshold Ca2+ concentrations (25-100 nM) and of enhancing Ca(2+)-induced Ca2+ release. Longitudinal muscle extracts incubated with beta-NAD+ produced a time-dependent increase in Ca(2+)-mobilizing activity identified as authentic cADPR by blockade of Ca2+ release with 8-amino-cADPR and ruthenium red. Ca2+ mobilizing activity was increased by cholecystokinin octapeptide (CCK-8) in a concentration-dependent fashion. The increase induced by CCK-8 was suppressed by the CCK-A antagonist, L364,718, nifedipine, and guanyl-5'-yl thiophosphate. The study shows that ADP-ribosyl cyclase can be stimulated by agonists and that cADPR can act as an endogenous modulator of Ca(2+)-induced Ca2+ release.

Adenosine Diphosphate Ribose↗
PubMed2001

Brown fat UCP1 is specifically expressed in uterine longitudinal smooth muscle cells.

Until now, uncoupling protein 1 (UCP1) was considered as unique to brown adipocytes. It supports a highly regulated uncoupling of oxidative phosphorylation that is associated with diet as well as with non-shivering thermogenesis. Here we report that UCP1 is not specific to brown adipocytes and can be expressed in longitudinal smooth muscle layers. In the uterus, this conclusion was drawn from different convergent data. A specific antibody against mouse UCP1 revealed, in mitochondrial fractions, a protein with the same molecular weight as brown fat UCP1. Sensitive and specific reverse transcriptase-polymerase chain reaction detected a mRNA whose sequence was totally homologous to that of brown fat UCP1 mRNA. Antibody against UCP1 as well as a UCP1 antisense probe specifically stained uterine longitudinal smooth muscles. UCP1 was also expressed in longitudinal smooth muscle of digestive and male reproductive tracts but was never expressed in other types of smooth muscle, including those of arterial vessels. In uterine tract, UCP1 content was increased after cold exposure or beta-adrenergic agonist treatment. It was also up-regulated during the postovulatory period after sexual cycle synchronization. Its content transiently increased during gestation and decreased markedly after birth. These regulations strongly argue about a role for UCP1 in thermogenesis as well as in relaxation of longitudinal smooth muscle layers.

Adipose Tissue, Brown↗
PubMed2003

Methods for comparison of parameters from longitudinal rhythmometric models with multiple components.

Multiple components linear least-squares methods have been proposed for the detection of periodic components in nonsinusoidal longitudinal time series. However, a proper test for comparison of parameters obtained from this method for two or more time series is not yet available. Accordingly, we propose two methods, one parametric and one nonparametric, to compare parameters from rhythmometric models with multiple components. The parametric method is based on techniques commonly and generally employed in linear regression analysis. The comparison of parameters among two or more time series is accomplished by the use of so-called dummy variables. The nonparametric method is based on bootstrap techniques. This approach basically tests if the difference in any given parameter obtained by fitting a model with the same periods to two different longitudinal time series differs from zero. This method calculates a confidence interval for the difference in the tested parameter. If this interval does not contain zero, it can be concluded that the parameters obtained from the two time series are different with high probability. An estimation of the p-value for the corresponding test can also be calculated. By the use of similar bootstrap techniques, confidence intervals can also be obtained for any parameter derived from the multiple component fit of several periods to nonsinusoidal longitudinal time series, including the orthophase (peak time), bathyphase (trough time), and global amplitude (difference between the maximum and the minimum) of the fitted model waveform. These methods represent a valuable tool for the comparison of rhythm parameters obtained by multiple component analysis, and they render this approach as a generally applicable one for waveform representation and detection of periodicities in nonsinusoidal, sparse, and noisy longitudinal time series sampled with either equidistant or unequidistant observations.

Blood Pressure↗
PubMed1983

A network of transverse and longitudinal intermediate filaments is associated with sarcomeres of adult vertebrate skeletal muscle.

An extensive network of transverse and longitudinal filamentous bridges was revealed when small myofibril bundles, prepared from Triton-EGTA-treated rabbit skeletal muscles, were extracted with Kl to remove the majority of thin and thick filaments. Transmission and scanning electron microscopic studies of these salt-resistant cytoskeletal residues indicated (a) small bundles of short transverse filaments connect adjacent myofibrils by forming Z to Z and M to M bridges; (b) parallel, continuous longitudinal filaments connect the peripheries of successive Z-disks and ensheath the sarcomere. These transverse and longitudinal filaments have the characteristic morphology of intermediate filaments; (c) two rings of tightly interwoven and tangled filaments, connected laterally by short filaments, encircle each Z disk. This double-ring also encircles a weblike meshwork which penetrates the sarcomeric space. From the peripheries of these rings, transverse and longitudinal intermediate filaments emerge; and (d) a massive amount of material translocated and accumulated near Z disks during Kl extraction. The residues were fairly resistant to solubilization by urea and SDS, and complete dissolution was achieved only with guanidinium chloride. SDS PAGE indicated that the residues consisted mainly of titin, nebulin, and variable amounts of residual myosin and actin. Desmin represented only a few percent of total residual proteins; however, it may be a major component of the intermediate filament network. We suggest that the intermediate filament should be considered an integral sarcomeric component that may play important cytoskeletal roles in muscle structure and mechanics.

Animals↗
PubMed1974

Longitudinal impedance of skinned frog muscle fibers.

Longitudinal impedance of skinned muscle fibers was measured with extracellular electrodes and an oil gap method in which a central longitudinal section of fiber is insulated by oil while the ends of the fiber are bathed in conducting pools of relaxing solution. Intact single fibers were isolated from frog semitendinosus muscle and the sarcolemma removed either by mechanical or chemical methods. Stray capacitance across the oil gap was measured after each experiment and its admittance subtracted from the admittance of the fiber and oil gap. Effects of impedance at the ends of the fiber were eliminated by measuring the impedance with two lengths of fiber in the oil gap and subtracting the impedance at the shorter length from that at the longer length. Longitudinal impedance so determined for mechanically and chemically skinned fibers exhibited zero phase shift from 1 to 10,000 Hz, i.e., the longitudinal impedance of skinned fibers is purely resistive. If we assume that our skinned fibers are a model of the sarcoplasm of muscle, we conclude that the equivalent circuit of the sarcoplasm is a resistor.

Animals↗
PubMed1975

Longitudinal impedance of single frog muscle fibers.

The longitudinal impedance of single skeletal muscle fibers has been measured from1 to 10,000 Hz in an oil gap apparatus which forces current to flow longitudinally down the fiber. The impedance observed is purely resistive in some fibers from the semitendinosus muscle and in two fibers from the sartorius muscle. In other fibers from the semitendinosus muscle a small phase shift is observed. The mean value of the maximum phase shift observed from all fibers is 1.07 degrees. The artifacts associated with the apparatus and method are examined theoretically and it is shown that one of the likely artifacts could account for the small phase observed. It is concluded that the longitudinal impedance of skeletal muscle fibers is essentially resistive and that little, if any, longitudinal current crosses the membranes of the sarcoplasmic reticulum.

Animals↗
PubMed2002

Pitch dependence of longitudinal sampling and aliasing effects in multi-slice helical computed tomography (CT).

In this work, we investigate longitudinal sampling and aliasing effects in multi-slice helical CT. We demonstrate that longitudinal aliasing can be a significant, complicated, and potentially detrimental effect in multi-slice helical CT reconstructions. Multi-slice helical CT scans are generally undersampled longitudinally for all pitches of clinical interest, and the resulting aliasing effects are spatially variant. As in the single-slice case, aliasing is shown to be negligible at the isocentre for circularly symmetric objects due to a fortuitous aliasing cancellation phenomenon. However, away from the isocentre, aliasing effects can be significant, spatially variant, and highly pitch dependent. This implies that measures more sophisticated than isocentre slice sensitivity profiles are needed to characterize longitudinal properties of multi-slice helical CT systems. Such measures are particularly important in assessing the question of whether there are preferred pitches in helical CT. Previous analyses have generally focused only on isocentre sampling patterns, and our more global analysis leads to somewhat different conclusions than have been reached before, suggesting that pitches 3, 4, 5, and 6 are favourable, and that half-integer pitches are somewhat suboptimal.

Artifacts↗
PubMed2002

The joint modeling of a longitudinal disease progression marker and the failure time process in the presence of cure.

In this paper we present an extension of cure models: to incorporate a longitudinal disease progression marker. The model is motivated by studies of patients with prostate cancer undergoing radiation therapy. The patients are followed until recurrence of the prostate cancer or censoring, with the PSA marker measured intermittently. Some patients are cured by the treatment and are immune from recurrence. A joint-cure model is developed for this type of data, in which the longitudinal marker and the failure time process are modeled jointly, with a fraction of patients assumed to be immune from the endpoint. A hierarchical nonlinear mixed-effects model is assumed for the marker and a time-dependent Cox proportional hazards model is used to model the time to endpoint. The probability of cure is modeled by a logistic link. The parameters are estimated using a Monte Carlo EM algorithm. Importance sampling with an adaptively chosen t-distribution and variable Monte Carlo sample size is used. We apply the method to data from prostate cancer and perform a simulation study. We show that by incorporating the longitudinal disease progression marker into the cure model, we obtain parameter estimates with better statistical properties. The classification of the censored patients into the cure group and the susceptible group based on the estimated conditional recurrence probability from the joint-cure model has a higher sensitivity and specificity, and a lower misclassification probability compared with the standard cure model. The addition of the longitudinal data has the effect of reducing the impact of the identifiability problems in a standard cure model and can help overcome biases due to informative censoring.

Journal Article↗
PubMed1976

Longitudinal fibre splitting in neurogenic muscular disorders--its relation to the pathogenesis of "myopathic" change.

In 15 patients with neurogenic muscular disorders, including cases of motor neuron disease, Wohlfart-Kugelberg-Welander disease, Davidenkow's scapuloperoneal syndrome, peripheral neuropathy and traumatic neuropathies, muscle biopsies were carried out, usually after EMG or single fibre EMG investigation. Enzyme histochemical and electronmicroscopic techniques were used to study longitudinal fibre splitting and its quantitative relation to the general changes in the biopsies. In 9 cases serial sections were used to study the longitudinal extent and character of fibre splitting. Longitudinal fibre splitting was found in 14 cases. It was prominent in Type 1 fibres, and in those biopsies in which hypertrophy was most marked. It was often associated with central migration of sarcolemmal nuclei. Ultrastructurally there was evidence that splitting consisted of mechanical disruption of the myofibrillar pattern, followed by an active process of membrane formation. We suggest that longitudinal splitting of muscle fibres, induced by overload of poorly innervated, hypertrophied fibres, can account for many of the "myopathic" changes found in neurogenic muscular disorders.

Adult↗
PubMed1999

Initial orthopaedic displacement compared with longitudinal displacement of the maxilla after a forward force application. An experimental study in dogs.

The aim of this study was to compare the initial orthopaedic displacement of the maxilla in vivo and the longitudinal changes after a forward force application. The sample consisted of five 1-year-old dogs. An anterior force of 5 N on the maxilla was applied by a coil spring system pushing between Brånemark implants and a maxillary splint. The initial displacement of the maxilla after force application was measured by means of speckle interferometry. The longitudinal displacement of the maxilla after a force application during 8 weeks was measured by superimposing standardized lateral cephalograms. The initial, as well as the longitudinal, displacement of the maxilla of the dogs was in a forward direction with some counterclockwise rotation. There was no statistical difference between the initial and longitudinal displacement. The biological response after force application during 8 weeks can be predicted by the initial orthopaedic displacement.

Animals↗
PubMed2005

Roentgen-cephalometric standards for a Swedish population. A longitudinal study between the ages of 5 and 31 years.

This study was performed to establish age- and gender-specific cephalometric normative data for a Swedish population. The material comprised 469 lateral cephalograms from two groups of subjects of Swedish origin between 5 and 31 years of age. All subjects (males and females) were diagnosed as 'normal' according to specified criteria and with no history of orthodontic treatment. Lateral cephalograms and body height measurements were taken at 5, 7, 10 and 13 years of age in one group (group E) (longitudinal follow-up). The same registrations were made in the other group (group U) at 7, 10 and13 years of age (mixed longitudinal type). Those 13 year olds were re-examined at 16, 19 and 31 years of age (longitudinal follow-up). No significant differences between age groups in the two samples were found. Therefore, subjects of the same age were combined. The study is hence regarded as a longitudinal follow-up from 5 to 31 years of age. The subjects were also grouped into dental development stages to widen the applicability of the cephalometric data.The craniofacial distances were constantly larger in males than in females, while no statistical differences as regards angular measurements were seen between genders. Distances as well as angular measurements varied with the different developmental periods. The results clearly verify that facial pattern changes existed during the observation period, with a growth acceleration of most distances between the 13 and 16 year recordings.

Adolescent↗