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PubMed1991

Blockage of longitudinal flow in endolymphatic hydrops.

The external shunt operation on the endolymphatic sac is based on the concept that it will drain excess endolymph and thus arrest the progression of endolymphatic hydrops. We performed histological studies on 46 temporal bones from 13 cases of bilateral and 20 cases of unilateral Meniere's disease to evaluate the status of the pathways of longitudinal flow of endolymph to the sac. The endolymphatic ducts were blocked in 8 specimens (17%), the endolymphatic sinuses in 9 (19.5%), the utricular ducts in 12 (26%), the saccular ducts in 7 (15%), and the ductus reuniens in 27 (59%). These blockages arrested longitudinal flow from both the pars superior and inferior in 21 cases (46%), the pars superior only in 3 (6.5%), and the pars inferior only in 16 (35%). In the 6 ears with all pathways open, 2 were found to have fistulae between the saccules and the perilymphatic spaces, which theoretically results in internal shunting, thus alleviating the need for the external shunt procedure. In the aggregate, therefore, 42 (91%) of 46 ears showed either areas of blockage of longitudinal flow or internal shunts that would theoretically negate the value of external endolymphatic shunt procedures. These temporal bones, however, are from an autopsy population and the severity of pathological changes is probably greater than it would have been at an earlier age when external shunt surgery might have been a therapeutic consideration.

Adult↗

PubMed1982

Effect of ovariectomy on longitudinal bone growth in the rat.

The effect of ovariectomy on longitudinal bone growth was studied in growing rats. The operation was performed at ages 20, 40, and 60 days. Sham operations were made at age 40 days. At different postoperative intervals, the growth rate was determined with the tetracycline technique, and the width of the growth plate was registered. After a slight initial retardation, the growth rate after ovariectomy was significantly greater than in normal rats during a 40-60 day period. During the same period, the growth plate was wider. The increase in growth rate was greater and more rapid if ovariectomy was performed in older animals. The results indicate that ovariectomy increases longitudinal bone growth and that longitudinal bone growth and skeletal maturation depend less on ovarial function in young animals than that in more mature animals.

Age Factors↗

PubMed1981

Correlative roentgenography and morphology of the longitudinal epiphyseal bracket.

Detailed examination of a complete chondro-osseous specimen from a patient with duplication of the first ray of the foot revealed the involved metatarsal had a trapezoid-shaped, diaphyseal-metaphyseal osseous unit that was longitudinally bracketed along the lateral side by a functioning physis, epiphysis, and secondary (epiphyseal) ossification center. The physis extended as an arc from the medial proximal side toward and along the lateral side and then back to the medial side distally. The medial side of the diaphysis had a normal periosteum. The longitudinal epiphyseal ossification bracket was a composite of initially separate proximal and distal secondary ossification centers that had progressively extended toward each other and finally coalesced along the laterally placed epiphyseal cartilage. We have termed this deformity the "longitudinal epiphyseal bracket" (LEB). The macroscopic and microscopic anatomy relevant to initial diagnosis and evaluation of sequential roentgenographic changes will be considered.

Bone Diseases, Developmental↗

PubMed1975

Effects of prostaglandins F2alpha and E1 on the longitudinal and circular smooth muscle of the guinea pig caecum in relation to the concentration of extracellular calcium.

Responses of the longitudinal and circular smooth muscle of the guinea-pig caecum were studied in media with different concentrations of extracellular calcium. A sucrose-gap method was used to record the electrical and mechanical parameters of smooth muscle activity. In the longitudinal smooth muscle no difference in the action of PGF2alpha and PGE1 was seen at low (0.8 mM), Normal (2.5 mM) or high (7.5 mM) concentrations of Ca2+. Both PG's stimulated the longitudinal strip and the action of acetylcholine at normal Ca2+ concentration was slightly inhibited immediately after the superfusion with the PG's and augmented thereafter. In the circular strip no significant difference between the stimulatory effect of PGF2alpha, and PGE1 in low and high Ca2+ solution was found. However at 2.5 mM Ca2+ PGF2alpha evoked much greater stimulation of the circular strip than did PGE1. After the end of the superfusion with either PG the effect of acetylcholine was inhibited by either PG at low Ca2+ level and potentiated at high Ca2+ level the effect of acetylcholine was inhibited by PGE1 but not by PGF2alpha. Thus, the effects of PGF2alpha and PGE1 on the circular smooth muscle differed from each other in their dependence on the concentration of extracellular calcium.

Acetylcholine↗

PubMed1982

Differential effects of SKF 10,047 (N-allyl-normetazocine) on peristalsis and longitudinal muscle contractions of the isolated guinea-pig ileum.

The purpose of this study was to investigate the differential involvement of distinct types of opioid receptors in the modulation of intestinal peristalsis compared to electrically induced longitudinal muscle contractions. Like naloxone, the proposed sigma-agonist and mu-antagonist SKF 10,047 (N-allyl-normetazocine) dose-dependently enhanced peristaltic circular muscle contractions in the isolated guinea-pig ileum. Pre-application of SKF 10,047 at a concentration which itself enhanced peristalsis by 20% on average strongly attenuated the inhibition of peristalsis produced by opioids previously proposed to act via mu-opioid-receptors in the guinea-pig ileum, i.e. normorphine, beta-endorphin, D-Ala2-D-Leu5-enkephalin and d-Ser2-L-Leu5-enkephalyl-Thr, but less strongly attenuated the inhibition produced by compounds suggested to act via kappa-opioid-receptors in this tissue, i.e. ethylketazocine and dynorphin (1-13). In contrast to its effect on peristalsis, SKF 10,047 inhibited the electrically induced contractions of the myenteric plexus-longitudinal muscle preparation in a naloxone-reversible fashion. It may be concluded that mu-and kappa-opioid receptors are of a greater functional significance than sigma-receptors in the control of peristalsis. sigma-Receptors might participate predominantly in modulating the release of acetylcholine which underlies the electrically induced longitudinal muscle contraction.

Animals↗

PubMed1986

A method of measurement of longitudinal resistances in an isolated cardiac and smooth muscle preparation.

The longitudinal internal as well as external resistance was measured by means of simultaneous intracellular and sucrose gap voltage recordings. The longitudinal internal resistance could be calculated from a formula comprising the shunt resistance, membrane action potential and transgap action potential before and after shunting. The longitudinal external resistance was calculated from another formula comprising the same quantities.

Animals↗

PubMed1976

Simultaneous recording of circular and longitudinal muscle contractions of the canine jejunum.

A method has been developed for monitoring the mechanical activities of individual longitudinal and circular muscles in a 5 millimeters long segment of intact intestine in the anesthetized dog. The longitudinal contractions were recorded by means of a new movement transducer. The circular contractions were recorded simultaneously using a water-filled intraluminal balloon. A precise separation of longitudinal and circular motor activities was obtained with this method. The two muscle layers manifested motor activity most of the time, but their contractions were out of phase. Phase locking was observed only during short periods of time. The contractions were then sequential, the circular one being first.

Animals↗

PubMed1993

Longitudinally oriented smooth muscle cells in rabbit arteries.

Intima formation in vessels, spontaneous or experimentally induced, is generally characterized by the presence of longitudinally oriented smooth muscle cells (LSMC). During an experiment of neo-intima induction in carotid arteries in rabbits, by application of a non-constrictive silastic cuff, a study was performed to investigate the presence of LSMC in the systemic and pulmonary circulations, in both elastic and muscular arteries. Three patterns could be distinguished: intimal cushions in muscular arteries, single or small groups of LSMC in the intima in elastic and larger muscular arteries, and intra-medially located layers or columns of LSMC in the aorta, the pulmonary artery, at the bifurcation of the aorta and around orifices of branches. In order to understand this peculiar orientation a biomechanical approach was used: this showed that near the lumen the circumferential stress is 4.5 times higher than the longitudinal. Because the cell surface of the smooth muscle cells exposed to this stress per unit vessel length is much less in the longitudinal than in the circular direction we conclude that the LSMC align in the direction which allows them to cope most effectively with the mechanical stresses.

Animals↗

PubMed1990

A new haemodynamic factor in cerebral AVM. Aspiration from the venous system demonstrated in two cases of pedonculo-Galen AVM successfully cured by occlusion of the superior longitudinal sinus.

Using a Doppler Mark 500 of ATL we measured the systolic and diastolic velocity of the red cells into the main arteries of the neck (diastolic rate cm/sec) thus approaching the flow in two cases of upper brain stem AVM with a unique drainage into the superior longitudinal sinus through an enlarged vein of Galen and a falcine sinus. Because of the desperate clinical condition of the children it was decided to stop the high blood flow by closing the aspiration coming from the low pressure of the venous system above and below the site of union between the malformation and the superior longitudinal sinus. An intra-operative and post-operative measurement of the diastolic rate showed a radical effect of the closure of the superior longitudinal sinus. The demonstration of this aspirative factor has allowed us to classify an AVM as a haemodynamic push-pull malformation.

Cerebral Angiography↗

PubMed1997

Role of nitric oxide in relaxation of the longitudinal layer of rectal smooth muscle.

PURPOSE: This study was designed to investigate the role of nitric oxide in neurogenic relaxation of the longitudinal layer of human rectal smooth muscle. METHODS: Tissue was obtained from the mid rectum of patients undergoing anterior resection for carcinoma. Adjacent strips of longitudinal muscle were dissected and mounted in organ baths for isometric tension recording. In preliminary experiments to determine the response of strips to cholinergic, adrenergic, and potential excitatory agonists, strips were superfused with standard Krebs solution (37 +/- 0.5 degrees C; pH, 7.4 +/- 0.05). Investigation of inhibitory, nonadrenergic noncholinergic responses required the addition of 3 x 10(-6) M histamine to induce reproducible and stable tension for five-minute "test" periods, during which electrical field stimulation (EFS) and additional drugs were applied. In these experiments, strips were superfused with Krebs solution that contained atropine sulfate (3 x 10(-6) M) and guanethidine (3 x 10(-6) M). RESULTS: The response to cholinergic and adrenergic agonists was typical of nonsphincter specialized gastrointestinal smooth muscle. EFS elicited frequency-dependent, neurogenic (tetrodotoxin-sensitive) relaxations of precontracted strips, which were reduced in dose-dependent fashion by addition of N omega-nitro-L-arginine and restored by addition of 3 x 10(-4) M L-arginine but not by D-arginine. Addition of exogenous nitric oxide (sodium nitroprusside) mimicked the relaxant response induced by EFS. CONCLUSION: Smooth muscle from the longitudinal layer of human rectum receives an intrinsic inhibitory innervation mediated by nitric oxide.

Aged↗

PubMedDate not supplied

The longitudinal distribution of cadmium, zinc, copper, iron, and metallothionein in the small-intestinal mucosa of rats after administration of cadmium chloride.

Different routes of Cd intake may influence the intestinal distribution of Cd, metallothionein (MT), and trace metals differently. Therefore, we compared the effects of parenteral and enteral administration of Cd on the distribution of trace metals and MT along the small intestine. In a first experiment three groups of rats were employed: a control, one receiving CdCl2 within the drinking water, and another receiving sc injections of CdCl2. In a second experiment, rats were fed three different diets with either 0, 0.3, or 1 mmol CdCl2/kg for one and two weeks to study the time- and dose-dependent effects of orally administered Cd. Metal concentrations (Cd, Zn, Cu, Fe) were measured by atomic emission spectrometry and MT was determined by radioimmunoassay. Intestinal MT levels did not show proximodistal gradients in controls or after sc administration of Cd, but orally administered Cd increased mucosal MT levels longitudinally from the duodenum to the ileum. Cd levels paralleled those of MT. Compared with the metal concentrations in the controls, sc administration of Cd did not change intestinal Zn, Cu, and Fe levels. Oral administration of Cd, however, increased Cu and decreased Fe levels in the intestinal mucosa significantly. The second experiment revealed that only high dietary concentrations of Cd increase intestinal Cd and MT levels longitudinally toward the distal parts, whereas at lower dietary concentration the longitudinal distribution was reversed. This shows that different routes and doses of Cd intake lead to a different trace metal and MT distribution and emphasizes the role of dietary Cd in the local induction of small-intestinal MT.

Administration, Oral↗

PubMed1997

Characterisation of pre- and post-synaptic alpha-adrenoceptors in modulation of the rat ileum longitudinal and circular muscle activities.

Previous study has shown that alpha2D-adrenoceptors are involved in modulation of peristalsis in the rat ileum. The aim of the present study was to determine the tissue location of alpha-adrenoceptors in the rat ileum by using a recently devised method. The pre-synaptic alpha-adrenoceptors were characterised by measuring the potencies of agonists to inhibit transmurally-evoked (1 ms pulses, 10 Hz, 8-10 s trains) contractions of the longitudinal and circular muscles and the affinities of antagonists. Post synaptic alpha-adrenoceptors were identified by screening agonists and antagonists in carbachol-contracted tissues. In the circular muscle the order of potencies for inhibiting transmurally-induced contraction was: clonidine > or = oxymetazoline > or = UK 14,304 > or = guanfacine > talipexole > phenylephrine > azepexole. The potency ratios relative to clonidine correlated to those previously derived using the rat ileum peristaltic reflex preparation. Most of the alpha-adrenoceptor agonists, however, caused only small inhibitions of the longitudinal muscle contraction in response to transmural stimulation, except phenylephrine and azepexole. RX 821002, yohimbine, rauwolscine, BRL 44408, phentolamine, idazoxan, ARC 239, and prazosin inhibited the effect of clonidine on the circular muscle response with apparent pK(B) values best correlated with pK(B) or pKi values derived from the rat ileum peristaltic reflex preparation and other tissues known to have the alpha2D-subtype. The rank order of potencies at inhibiting carbachol-induced responses of both muscle layers was: phenylephrine > or = oxymetazoline > clonidine > or = talipexole > azepexole >> guanfacine. UK 14,304 was inactive up to 10 microM. The EC50 value of each agonist on the longitudinal muscle was not significantly different to the corresponding value on the circular muscle. Prazosin was more potent than yohimbine at inhibiting the relaxant effect of phenylephrine in both muscle layers of carbachol-contracted tissues. It is concluded that the recently identified alpha2D-adrenoceptors of the rat ileum are located on cholinergic neurons controlling circular muscle contraction. The study also demonstrated the presence of postsynaptic alpha1-adrenoceptors involved in mediating relaxation in both muscle layers.

Adrenergic alpha-Agonists↗

PubMed2003

The longitudinal Young's modulus of cortical bone in the midshaft of human femur and its correlation with CT scanning data.

This study was concerned with establishing the regional variations in the magnitude of the longitudinal Young's modulus of the cortical bone in the femoral midshaft and with investigating whether a relationship existed between the Young's modulus of bone and the CT number. Were such a relationship to exist this would provide a noninvasive method of assessing the quality of bone in the regions of fixation of implants to bone. The data would be of considerable aid to designers of implant stems to withstand the stresses arising at its interface with the bone. Five pairs of fresh frozen human femora were used. Several beam-shaped small specimens were methodically harvested from each pair and were used to measure the longitudinal modulus adopting the three-point bending test, which was carried out with a specially constructed and validated apparatus. CT scans of the bone were obtained, prior to harvesting the specimens, and the CT number was measured at locations corresponding with the specimen sites. The results indicate that in the femoral midshaft the cortical bone has an average Young's modulus value of 18600 +/- 1900 MPa. This agrees well with data obtained by other researchers using different experimental methods. Statistical analyses revealed no regional variations in the value of the longitudinal modulus of the bone. No correlation was found between the bone modulus and the CT number. Thus a noninvasive method for establishing the bone properties still remains a challenge.

Aged↗

PubMed2000

2-Methoxyestradiol inhibits longitudinal bone growth in normal female rats.

2-Methoxyestradiol (2-MeO-E(2)), a major metabolite of 17beta-estradiol, may function as a physiological tumor suppressor and is being investigated for clinical applications. It has been reported to target rapidly dividing cells. We investigated the effects of 2-MeO-E(2) on the growth plate of young rats because normal longitudinal bone growth requires rapid proliferation of cartilage and endothelial cells. Sexually mature (3-month-old) normal female rats were treated with 2-MeO-E(2) (100 mg/kg/day) for 13 days and it was found to have no effect on uterine weight but reduced serum cholesterol. The estrogen metabolite had no effect on either cortical or cancellous bone. In contrast, 2-MeO-E(2) dramatically reduced longitudinal bone growth rate at the proximal tibia from 55 +/- 2 to 20 +/- 2 microm/day (P < 0.001) and growth plate thickness from 153 +/- 14 to 70 +/- 6 microm (P < 0.001). The latter decrease was due to significant reductions in the height of both the proliferative (P < 0.001) and the hypertrophic (P < 0.001) zones. These results in normal female rats demonstrate that 2-MeO-E(2) inhibited longitudinal bone growth but had no effect on either radial bone growth or cancellous bone turnover. 2-MeO-E(2) was shown by these studies to have the ability to discriminate between bone and cartilage, as well as between reproductive and nonreproductive estrogen-target tissues. Thus, 2-MeO-E(2) is a naturally produced estrogen metabolite that demonstrates unique tissue selectivity.

2-Methoxyestradiol↗

PubMed1998

Shortening velocity is different in longitudinal and circular muscle layers of the rabbit urethra.

The aim of the study was to investigate whether the functional difference between circular and longitudinal muscles in the female rabbit urethra is reflected in their shortening properties and lactate dehydrogenase (LDH) activity. For mechanical experiments the preparations were chemically skinned to avoid influence of membrane-related mechanisms and to enable maximal activation. Force velocity relations and the maximal shortening velocity (v(max)) were determined using the isotonic quick-release method. The v(max) was three times higher in longitudinal muscle. LDH isoform pattern was determined on agarose gels. The M-subunit, favourable for lactate formation, constituted 70% of the total in both types of muscle. There was no difference in the LDH isoform pattern despite the marked difference in v(max). We conclude that the difference in v(max) reflects differences in the contractile machinery itself. These mechanical characteristics are advantageous for the role of the circular as a tonic muscle contracting during bladder filling, and the longitudinal as a phasic muscle active in opening up the urethra during micturition.

Animals↗

PubMed2000

A longitudinal insufficiency fracture of the tibia in association with a healed chronic osteomyelitis.

Longitudinal stress fracture of the tibia often present with an atypical clinical presentation which can be mistaken for osseous tumor or osteomyelitis. We present a case of longitudinal stress fracture of the tibia which occurred in a patient with healed chronic osteomyelitis of the tibia. Magnetic resonance imaging failed to make the correct diagnosis. Accurate diagnosis was only obtained by helical CT which showed the longitudinal fracture line. Magnetic resonance imaging showed only non-specific signs of bone marrow edema, suggesting recurrence of osteomyelitis. Magnetic resonance imaging can be misleading in the absence of direct visualization of the fracture line.

Adult↗

PubMed2001

Myelin as longitudinal conductor: a multi-layered model of the myelinated human motor nerve fibre.

The myelin sheath is normally regarded as an electrical insulator. Low values of radial conductance and capacitance have been measured, and in electrical models of myelinated axons the contribution of longitudinal conduction within the sheath has been ignored. According to X-ray diffraction studies, however, myelin sheaths comprise alternate lipid and aqueous layers, and the latter may be expected to have a low resistivity. We propose a new model of myelinated axons in which the aqueous layers within the myelin provide appreciable longitudinal and radial conductance, the latter via a spiral pathway. We have investigated the likely contribution of these conductive paths within the myelin to the electrical properties of a human motor nerve fibre by computer simulation, representing the myelin sheath as a series of interconnecting parallel lamellae. With this new model, action potential conduction has been simulated along a 20-node cable, and the electrotonic responses to 100-ms depolarizing and hyperpolarizing current pulses have been simulated for a uniformly polarized fibre. We have found that the hypothesis of a longitudinally conducting myelin sheath improves our previous model in two ways: it is no longer necessary to make implausible assumptions about the resistivity or width of the periaxonal space to simulate realistic electrotonus, and the conduction velocity is appreciably faster (by 8.6%).

Electric Conductivity↗

PubMed2000

Projections and neurochemical coding of motor neurones to the circular and longitudinal muscle of the guinea pig gastric corpus.

The present study identified projection and neurochemical coding patterns of intrinsic circular (CMN) and longitudinal muscle motor neurones (LMN) in the guinea pig stomach by using the retrograde tracer DiI (1,1'-didodecyl-3,3,3',3'-tetramethylindocarbocya-nine perchlorate) in combination with the immunohistochemical demonstration of choline acetyltransferase (ChAT), enkephalin (ENK), neuropeptide Y (NPY), nitric oxide synthase (NOS) and substance P (SP). Populations of LMN and CMN had similar neurochemical coding and a clear polarity of projection. Taking all DiI-labeled cell bodies as 100%, ascending pathways exhibited the coding ChAT/- (CMN:14.7%/LMN: 18.3%), ChAT/ENK (15.7%/10.1%), ChAT/SP/+/-ENK (19.2%/16.4%), or ChAT/NPY (4.4%/7.6%); descending pathways had the coding NOS/- (13.8%/16.9%), NOS/NPY (9.9%/17%), NOS/ENK (4.4%/1.2%) or NOS/NPY/ENK (13.0%/5.5%). The relative contributions of these populations were not different between CMN and LMN. However, target-specific projection patterns were revealed: most LMN (82%) had longitudinal whereas most CMN (58%) had circumferential projection preferences. The results indicate that gastric circular and longitudinal muscle layers are innervated by ascending excitatory and descending inhibitory pathways in the myenteric plexus. The projection patterns of CMN and LMN were different and followed the orientation of the muscle layers. It is suggested that the specific muscle motor pathways in the gastric myenteric plexus coordinate the reflex-mediated phasic and tonic activity of gastric muscle layers.

Animals↗