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Laparoscopic lateral L4-L5 disc exposure.

BACKGROUND: The anterior laparoscopic approach requires precarious dissection around the iliac vessels to expose the L4-L5 level. Furthermore, a retroperitoneal endoscopic approach to the L4-L5 level requires a technically demanding dissection to access the L5-S1 disc space. A unique lateral laparoscopic approach to the L4-L5 disc space allows concurrent access to the L5-S1 space while avoiding major dissection around the iliac vessels. This article describes this novel lateral approach and reviews the initial clinical outcomes. METHODS: Between January 1999 and April 2000, five patients underwent laparoscopic lateral L4-L5 disc exposure at the Cleveland Clinic Foundation. All charts were reviewed retrospectively. Mean values +/- standard deviation were determined for patient demographics and operative characteristics. A standard five-port laparoscopic technique was used. The sigmoid colon was retracted medially with an endoloop. The retroperitoneum was entered and the ureter and left iliac artery were retracted medially, whereas the psoas was retracted laterally. Fluoroscopy delineated the L4-L5 disc space allowing discectomy and cage insertion. Postoperatively, subjective patient satisfaction was obtained and radiologic evidence of fusion was assessed. RESULTS: All five patients were males, with a mean age of 47.4 +/- 7 years and a body mass index of 30 +/- 6 kg/m2. Four patients had an L4-L5 and L5-S1 fusion and one patient had an L4-L5 and L3-L4 fusion. Mean operative time was 349 +/- 32 min, with a mean blood loss of 210 +/- 74 cc. There were no intraoperative complications and no conversions, and postoperatively all patients were started on a clear liquid diet on postoperative day 1. The mean length of stay was 3.4 +/- 0.9 days. Patients returned to work in a mean of 12 +/- 7 weeks. All patients had evidence of fusion on their radiologic follow-up. Four patients were pain free, whereas one patient required intermittent narcotics at 1-year follow-up. CONCLUSIONS: For multilevel fusions including the L4-L5 disc space, the lateral laparoscopic exposure is a safe and efficacious procedure allowing simultaneous access to multiple disc spaces while avoiding the sympathetic chain, ureter, and major vascular structures. The lateral approach affords excellent exposure for accurate deployment of the appropriate orthopedic hardware.

Adult↗

Anterior, lateral, and posterior retroperitoneal approaches in endoscopic adrenalectomy.

BACKGROUND: Three approaches are currently used for endoscopic adrenalectomy-the lateral (transperitoneal), the posterior (retroperitoneal), and the anterior (transperitoneal). Both the lateral and posterior approaches are performed with the patient placed in the flank decubitus position; in the anterior approach the patient is supine. This study was designed to compare these three types of access in a relatively large series of patients undergoing adrenalectomy at three different institutions. METHODS: Laparoscopic adrenalectomy was performed in 216 patients with a variety of adrenal disorders, including 66 patients with Conn's syndrome, 55 with incidentaloma, 58 with Cushing's syndrome, 33 with pheochromocytoma, two with virilizing adrenogenital syndrome, and two with other lesions. Seventy-two adrenalectomies were performed using the lateral access, 67 via the posterior approach, and 77 via the transperitoneal anterior approach. There were 111 right and 105 left lesions. RESULTS: One patient in the lateral access group and three patients in the posterior group required conversion to open surgery. No conversions were needed in the anterior group. The learning curve was statistically significant only in the anterior access group. In both of the transperitoneal approaches (lateral and anterior), a statistically significant correlation was found between the operative time and the patient's body mass index (BMI). The postoperative hospital stay and time needed to return to normal activities were similar for the three groups. One patient who underwent retroperitoneal adrenalectomy for Cushing' disease died in the postoperative period of Candida sepsis and peritonitis. CONCLUSIONS: The anterior access route requires that the surgeon be skilled in advanced laparoscopic surgery. Both of the transperitoneal approaches (anterior and lateral) are suitable to remove larger adrenal masses. The posterior access may represent a better option in obese patients or in cases with small lesions.

Adolescent↗

Cervical spine injuries associated with lateral mass and facet joint fractures: new classification and surgical treatment with pedicle screw fixation.

To clarify the injury pattern, initial spinal instability, degree of discoligamentous injuries in cervical lateral mass and facet joint fractures, we retrospectively analyzed radiological parameters and introduced a new classification for these injuries. Surgical treatment was performed with cervical pedicle screw fixation (CPS), and overall neurological and radiological outcome was evaluated with a minimum follow-up period of 2 years. Lateral mass fractures were divided into the following four subtypes: separation, comminution, split, and traumatic spondylolysis. The sagittal and frontal alignments were evaluated at both mainly injured and adjacent spinal segments on radiographs. The initial discoligamentous injuries were investigated on magnetic resonance imaging in terms of their frequencies, subtype of injuries, and involved spinal levels. Anterior translation of fractured vertebra was demonstrated in 77% of lateral mass fractures, while 24% of anterior translation was observed, even in cephalad-adjacent vertebrae. On magnetic resonance imaging, signal changes in anterior longitudinal ligament (ALL) and intervertebral disc were demonstrated in 76% of caudal segments and 24% of cephalad segments adjacent to fractured vertebra of lateral mass fractures. The subtype analyses of lateral mass fractures demonstrated high rates of anterior translation in separation, split, and traumatic spondylolisthesis, as well as significant coronal malalignment in comminution and split types (p<0.05). Thirty-one patients underwent surgical treatments using a cervical pedicle screw fixation. The CPS provided the superior capability of deformity correction without pseudoarthrosis, as well as excellent neurological recovery. The average numbers of stabilized segments were minimized without serious complications. In separation, facet joint fracture, and fractures with mild lateral mass comminution, the single level posterior fixation can be considered. The significant unstable injuries of split and comminution type with coronal malalignment can be treated with exclusive two-level posterior stabilization with CPS. The initial evaluation of fracture subtypes helps to successfully minimize the stabilized spinal segment.

Adolescent↗

Abnormal lateral notch in knees with anterior cruciate ligament injury.

We reviewed plain radiograms of anterior cruciate ligament injuries to determine the frequency of an abnormal lateral notch found in the lateral femoral condyle, and we investigated a possible mechanism for its occurrence by determining the relationship with associated injuries. We analyzed data for 216 patients who underwent ACL reconstruction between 1993 and 1996, whose radiographic images of the contralateral knee were available. The numbers of male and female patients were 122 and 94, respectively, and their ages ranged from 14 to 47 years (average, 25 years). The abnormal notch visualized by lateral radiograph was found in 66 of 216 knees (30. 6%) and was classified into three types. The type of abnormal notch seen most frequently (73%) was located at the same site as the notch on the contralateral side, but appeared deeper than normal. Knees with abnormal notches showed lateral meniscal injuries more frequently than those without such notches (P<0.005). The abnormal notch was assumed to have formed at the time of injuries, after impingement of the lateral femoral condyle on the lateral tibial condyle. Cartilage damage at the abnormal notch should be carefully observed in the future.

Adolescent↗

Lateral roots affect the proteome of the primary root of maize (Zea mays L.).

Lateral roots are initiated from the pericycle cells of other types of roots and remain in contact with these roots throughout their life span. Although this physical contact has the potential to permit the exchange of signals, little is known about the flow of information from the lateral roots to the primary root. To begin to study these interactions the proteome of the primary root system of the maize (Zea mays L.) lrt1 mutant, which does not initiate lateral roots, was compared with the corresponding proteome of wild-type seedlings 9 days after germination. Approximately 150 soluble root proteins were resolved by two-dimensional electrophoresis and analyzed by MALDI-ToF mass spectrometry and database searching. The 96 most abundant proteins from a pH 4-7 gradient were analyzed; 67 proteins representing 47 different Genbank accessions were identified. Interestingly, 10 (15/150) of the detected proteins were preferentially expressed in lrt1 roots that lack lateral roots. Eight of these lrt1-specific proteins were identified and four are involved in lignin metabolism. This study demonstrates for the first time the influence of lateral roots on the proteome of the primary root system. To our knowledge this is the first study to demonstrate an interaction between two plant organs (viz., lateral and primary roots) at the level of the proteome.

Electrophoresis, Gel, Two-Dimensional↗

The relationship of inferior ST depression, lateral ST elevation, and left precordial ST elevation to myocardium at risk in acute anterior myocardial infarction.

The purpose of this study was to examine the relationship between the presence or absence of ST segment depression in inferior leads (II, III, and aVF) and ST segment elevation in lateral (I and aVL) or left precordial (V5 and V6) leads with the amount and location of myocardium at risk for infarction in patients with acute anterior myocardial infarction. Forty-three patients with anterior infarctions were injected with technetium 99m-sestamibi when they were first seen and underwent tomographic imaging to measure the amount and location of myocardium at risk. Patients with inferior ST depression (n = 10) compared with those without ST depression (n = 33) had perfusion defects that extended significantly further into the lateral wall (47 degrees vs 20 degrees, p = 0.04) and larger anterior injury vectors (6.47 vs 4.92, p = 0.008). There was no significant association with the percentage of myocardium at risk, disease of the right coronary artery, the presence of an inferior perfusion defect, or the size of the inferior injury vector. Among the patients with ST elevation in lateral leads (n = 16) compared with those without (n = 27), there was a significantly more lateral defect border (47 degrees vs 25 degrees, p = 0.007) and a larger anterior injury vector (6.07 vs 4.81, p = 0.01). There was no significant correlation with the percentage of myocardium at risk. A significant relationship could not be demonstrated between the presence of ST elevation in the left precordial leads and any measure of the amount or location of myocardium at risk. These data support the theory that inferior ST depression in patients with transmural anterior ischemia is a "reciprocal" finding and does not represent inferior ischemia. The presence of inferior ST depression or lateral ST elevation is associated with a more lateral perfusion defect. Neither of these ECG findings is associated with the amount of myocardium at risk for infarction.

Adult↗

Congruous and incongruous sectoral visual field defects with lesions of the lateral geniculate nucleus.

Quantitative perimetric studies in two women, each 52 years of age, with involvement of the lateral geniculate nucleus (caused by a small arteriovenous malformation in one and by an astrocytoma in the other) disclosed a striking wedge-shaped horizontal sectoranopia that was perfectly congruous in one case and incongruous in the other. Selective interruption of the dual blood supply to the lateral geniculate nucleus (with the anterior choroidal artery supplying the anterior hilus, together with the anterior and lateral nucleus and the lateral choroidal artery supplying the remainder of the nucleus) may result in a congruous visual field defect with steeply sloping borders because such a lesion must respect the anatomic boundaries produced by this vascular supply. Partial infiltration or involvement of the lateral geniculate nucleus (where uncrossed retinal projections terminate in one group of laminae, while crossed retinal projections terminate in another) provides a logical explanation for the occurrence of incongruous visual field defects. This unusual horizontal wedge-shaped defect should suggest lateral geniculate nucleus involvement, especially in the absence of trauma.

Choroid↗

Effect of sterol structure on molecular interactions and lateral domain formation in monolayers containing dipalmitoyl phosphatidylcholine.

Molecular associations between different sterols and dipalmitoyl phosphatidylcholine (DPPC) were examined in monolayers at the air/water interface. The sterols examined included cholesterol, 5-cholesten-3- one, 4-cholesten-3 beta-ol, 4-cholesten-3-one, cholesteryl acetate, and cholesteryl methyl-and ethyl ether. Information about the long-range order in pure sterol monolayers, as well as lateral domain-formation in mixed sterol/DPPC monolayers was obtained from the lateral miscibility or distribution of NBD-cholesterol (present at 0.5 mol%), as determined by monolayer epifluorescence microscopy. It was observed that the miscibility of NBD-cholesterol with the host sterol was limited in all monolayers except those of 5-cholesten-3-one and 4-cholesten-3-one, suggesting that only these monolayers lacked a long-range order present in the other sterol monolayers. Note that the term long-range order does not necessarily imply that the monolayer is solid. In mixed monolayers containing 3 beta-OH sterols and DPPC, cholesterol formed laterally condensed domains whereas 4-cholesten-3 beta-ol did not. This finding suggest that the sterols/DPPC interaction is sensitive to the position of the double-bond of the sterol molecule (delta 5 versus delta 4). Neither of the 3-keto sterols formed laterally condensed domains with DPPC. Cholesteryl acetate, however, formed lateral domains with DPPC which were in part similar to those seen in the cholesterol/DPPC system. The domains formed were circular, indicating their fluid nature. Mixed monolayers containing either of the ether sterol derivatives failed to produce clearly defined condensed domains with DPPC, although both mixed monolayers had a surface texture which suggested some degree of nonuniform distribution of the fluorescent probe. In summary, these novel results directly demonstrate the selective importance of both the delta 5 double bond, as well as of specific functional groups at the 3-position, for the molecular association with DPPC, and consequently for the formation of sterol/phospholipid-rich lateral domains.

1,2-Dipalmitoylphosphatidylcholine↗

On the projections from the vestibular and perihypoglossal nuclei to the spinal trigeminal and lateral reticular nuclei in the cat.

The projection from the vestibular and perihypoglossal nuclei to the spinal trigeminal and lateral reticular nuclei has been studied in cats where the wheat germ agglutinin-horseradish peroxidase complex has been used as a retrograde tracer. All injections were made at the level of the caudal pole of the inferior olive. The medial and descending vestibular, and the perihypoglossal nuclei were found to project to the spinal trigeminal nucleus. The projection to the lateral reticular nucleus reaches its medial-most part only, and originates in the lateral vestibular nucleus. The lateral part of the reticular formation also appears to be the target for some vestibular efferent fibres, mainly from the descending vestibular nucleus. The retrogradely labelled cells within the medial and descending vestibular nuclei are of all sizes and distributed throughout their entire territory. Certain observations furthermore indicate that the fibres reaching the lateral reticular nucleus are collaterals only from the vestibulospinal tract. The projections are bilateral. The observations confirm and extend previous observations on the afferent projections to the spinal trigeminal and lateral reticular nuclei.

Animals↗

Segregation of electroreceptive and mechanoreceptive lateral line afferents in the hindbrain of chondrostean fishes.

The anterior lateral line nerve (ALLN) in the chondrostean fishes (sturgeon and paddlefishes) consists of both fibers innervating ampullary electroreceptors and fibers innervating the mechanoreceptive neuromasts of the cephalic lateral line system. The fibers of the posterior lateral line nerve (PLLN) innervate only mechanoreceptive neuromasts on the body trunk. The ALLN enters the medulla via dorsal and ventral roots; the dorsal root projects to the dorsal octavolateralis nucleus (DON), whereas the ventral root and the PLLN project principally to the medial octavolateralis nucleus (MON). Previous studies in elasmobranchs have demonstrated that fibers of the dorsal root of the ALLN convey electrosensory information, and fibers of the ventral root are concerned with mechanoreceptive information. Electrophysiological and neuroanatomical methods are employed in this study in order to determine if there exists a similar segregation of electroreceptive and mechanoreceptive lateral line afferents within the chondrostean medulla. In specimens of shovelnose, Scaphirhynchus platorynchus, and Atlantic sturgeon, Acipenser oxyrhynchus, and paddlefish, Polyodon spathula, evoked potentials recorded from the hindbrain and elicited by electric fields reached maximum amplitude within the DON and decreased in amplitude through the cerebellar crest. Evoked potentials elicited by stimulation of the posterior lateral line nerve achieved maximum amplitude within the MON. Single and multiple unit recordings revealed that units within the DON responded only to electric field stimulation, whereas units recorded in the MON responded only to mechanical stimulation. Horseradish peroxidase implanted beneath isolated patches of ampullae in Polyodon revealed fibers innervating electroreceptors projecting to the DON via the dorsal root of the ALLN. These results demonstrate a segregation of electroreceptive and mechanoreceptive lateral line afferent fibers in the chondrostean hindbrain, similar to that seen in elasmobranchs. This supports the contention that the electrosensory systems of elasmobranchs and chondrosteans are homologous, and are derived from the common ancestor of elasmobranch and actinopterygian fishes.

Animals↗

The organization of the rat lateral geniculate body by immunohistochemical analysis of neuroactive substances.

The organization of neuroactive substances in the rat lateral geniculate body (LGB) was studied with available immunohistochemical stainings. In the dorsal lateral geniculate nucleus (DLG), there existed only gamma-aminobutyric acid (GABA)-like immunoreactive neurons. Immunoreactive fiber plexuses for substance P (SP), cholecystokinin-8 (CCK) and vasoactive intestinal polypeptide (VIP) were present in the lateral margin of the DLG, just beneath the optic tract. There were immunoreactive neurons and fibers for GABA, SP, leucine-enkephalin (ENK) and neuropeptide Y (NPY) in the intergeniculate leaflet (IGL). ENK-, NPY- and SP-like immunoreactive neurons in the IGL were mainly medium-sized, and bipolar or spindle-shaped with a few dendrites oriented dorsoventrally. In the IGL, use of double-labeled immunofluorescence demonstrated that a few neurons exhibited both ENK- and SP-like immunoreactivities, and a few neurons had both GABA- and ENK-like immunoreactivities. Although the morphology of ENK-like immunoreactive neurons resembled to NPY-like immunoreactive neurons, both neurons were clearly different neurons. Many GABA-, ENK- and SP-like immunoreactive neurons and fibers were found in the ventral lateral geniculate nucleus (VLG). These immunoreactive neurons were mainly medium-sized, and bipolar in shape, while a few immunoreactive neurons were of multipolar shape. Neurons containing ENK and fibers containing SP mainly existed in the lateral half of the parvocellular part and in the medial half of magnocellular part of the VLG. In this region, about one-third of the GABA-like immunoreactive neurons contained ENK-like immunoreactivity. Many SP neurons mainly existed in the medial half of the parvocellular part of the VLG. CCK- and VIP-like immunoreactive fibers were present in the lateral half of the magnocellular part of the VLG. Immunoreactive fibers for calcitonin gene-related peptide, corticotropin-releasing factor, neurotensin and tyrosine hydroxylase were disseminated throughout the LGB. The subdivisions of the LGB were discussed, based upon the distribution of neuroactive substances.

Animals↗

Dopamine agonists and stress produce different patterns of Fos-like immunoreactivity in the lateral habenula.

In rats treated systemically with either amphetamine, amfonelic acid or apomorphine, large numbers of cells displaying Fos-like immunoreactivity (FLI) could be seen in the lateral zone of the lateral habenula. The induction of FLI by amphetamine could be blocked either by pretreatment with haloperidol or by 6-hydroxydopamine lesions of ascending dopamine fibers at the level of the lateral hypothalamus. In contrast, a variety of stressors selectively induced FLI in the most medial portion of the lateral habenula. These findings support the concept of a functional differentiation of the medial and lateral regions of the lateral habenula and provide further evidence for involvement of the habenula in the circuitry of the basal ganglia.

Animals↗

High-pressure proton NMR study of lateral self-diffusion of phosphatidylcholines in sonicated unilamellar vesicles.

Effects of pressure on the lateral diffusion of phospholipid molecules in sonicated pure 1,2-dipalmitoylphosphatidylcholine (DPPC) and 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) vesicles (15 wt%) in D2O were examined using the high-pressure proton NMR rotating frame spin-lattice relaxation time (T1rho) method. Proton T1rho were measured at pressures from 1 bar to 5000 bar and at temperatures of 50 degrees C to 70 degrees C for DPPC and 5 degrees C to 35 degrees C for POPC. The T(-1)1rho values were plotted as a function of the square root of the spin-locking field angular frequency (omega1(1/2) and the lateral diffusion coefficient (D) calculated from the slope. Pressure effects on lateral diffusion were observed in the liquid-crystalline (LC) phase. The lateral diffusion coefficient exhibited sharp decreases in response to the various pressure-induced phase transitions encountered. However, pressure had little, if any, effect on lateral diffusion in the pressure-induced gel I (GI) phase and pressure-induced interdigitated gel (Gi) phase. The activation volumes for diffusion were calculated from the slopes from plots of In D versus pressure for both DPPC (37 ml/mol at 50 degrees C, 34 ml/mol at 60 degrees C and 25 ml/mol at 70 degrees C) and POPC (16 ml/mol at 5 degrees C, 9 ml/mol at 20 degrees C and 6 ml/mol at 35 degrees C) sonicated vesicles in the LC phase. The activation energy for diffusion (Ea) was calculated using the slopes from plots of In D versus the inverse of the temperature (1/T) for both DPPC and POPC in the LC phase (3.5 kcal/mol and 3.9 kcal/mol, respectively) and for both DPPC and POPC in the GI phase (6.0 kcal/mol and 4.4 kcal/mol, respectively). From the lateral diffusion coefficient and line width data pressure-temperature phase diagrams for sonicated pure DPPC and POPC vesicles were constructed. The values of the temperature to pressure equivalence of DPPC (dTm/dP) were estimated to be 22.1 degrees C/kbar for the LC to GI phase transition and 28.6 degrees C/kbar for the GI to Gi phase transition. The value of the temperature to pressure equivalence of POPC for the LC to GI phase transition was estimated to be 19.0 degrees C/kbar.

1,2-Dipalmitoylphosphatidylcholine↗

Role of the lateral tegmental field in the central sympatho-inhibitory effect of 8-hydroxy-2-(di-n-propylamino)tetralin in the cat.

Cardiovascular neurones with sympathetic nerve and cardiac related activity have been detected in the lateral tegmental field and have been classified depending on their response to baroreceptor activation. Baroreflex activation decreased and increased the firing rate of sympatho-excitatory neurones and sympatho-inhibitory neurones respectively. Intravenous (i.v.) administration of 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin) (1 to 30 micrograms/kg) produced a dose-dependent decrease in the firing rate of sympatho-excitatory neurones in conjunction with a decrease in renal sympathetic nerve activity. 8-OH-DPAT had a variable effect (excitation or inhibition) on the firing rate of sympatho-inhibitory lateral tegmental field neurones. Both the excitatory and the inhibitory effects of 8-OH-DPAT were reversed by spiperone (1 mg/kg i.v.). Microinjection of 8-OH-DPAT (2 nmol/site) into the lateral tegmental field decreased blood pressure and renal sympathetic nerve activity. Compared with the effects elicited by microinjection of 8-OH-DPAT into the rostral ventrolateral medulla, the renal sympatho-inhibitory response elicited by 8-OH-DPAT injected into the lateral tegmental field appeared smaller. Chemical lesions of the lateral tegmental field neurones with kainic acid produced hypertension and sympatho-excitation. The correlation between renal sympathetic nerve activity and the R wave of the electrocardiogram disappeared after treatment with kainic acid. Subsequent i.v. 8-OH-DPAT (1 to 100 micrograms/kg) failed to alter blood pressure and renal sympathetic activity. In contrast clonidine (1 to 10 micrograms/kg) still decreased blood pressure, heart rate and renal sympathetic nerve activity in kainic acid-lesioned animals and these effects were reversed by the alpha 2-adrenoceptor antagonist, methoxy-idazoxan (10 micrograms/kg i.v.). The data described indicate that the lateral tegmental field plays a role in the central cardiovascular effects of 8-OH-DPAT and that the integrity of this area is necessary for the expression of the sympatho-inhibitory effects of the drug.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

The lateral mobility of cell membrane components is not altered following cell fusion induced by Sendai virus.

The interaction of Sendai virus glycoproteins with cell membranes was proposed to increase the lateral mobility of membrane proteins, enabling membrane fusion and the aggregation of intramembrane particles by thermotropic separation (Volsky, DJ & Loyter, A, Biochim biophys acta 514 (1978) 213 [13]; Maeda, T et al. Exp cell res 123 (1979) 333 [15]; and Kim, J & Okada, Y, Exp cell res 132 (1981) 125 [44]). In order to test this hypothesis, we employed fluorescence photobleaching recovery to investigate the effects of Sendai virus-induced fusion on the lateral mobility of membrane proteins and lipids in a variety of cell types (human erythrocytes, BHK21, HeLa, 3T3 NIH, and mouse spleen lymphocytes). The results of the lateral diffusion measurements demonstrate that no significant alterations occur in the lateral motion of membrane proteins or a fluorescent phospholipid on all the cell types examined, including cells which revealed high susceptibility to the virally mediated fusion (human erythrocytes and BHK21 cells). These findings suggest that a permanent increase in the lateral mobility of cell surface components does not generally occur during Sendai virus-induced cell fusion, and thus cannot play a role in the fusion mechanism. The possible involvement of transient alterations in the lateral mobility of membrane components in the fusion mechanism is discussed.

Animals↗

Seasonal variations of serotonin content in the pineal complex and the lateral eye of Lampetra planeri (cyclostoma, petromyzontidae).

Serotonin concentrations were measured by spectrofluorimetry in the pineal complex and the lateral eyes of Lampetra planeri, living in a natural environment, throughout two consecutive years. Large seasonal fluctuations with bimodal annual patterns of variations were observed in both the pineal complex and the lateral eyes. In the pineal complex, peak values occurred in February and August and low values in April and November. In the lateral eyes, peak values occurred in March and September. Comparison of the serotonin concentrations between the pineal complex and the lateral eyes showed that in ammocoetes the serotonin concentrations were similar in these organs, while in metamorphosing forms and adults the serotonin concentrations were significantly higher in the lateral eyes. The physiological significance of the seasonal variations of serotonin observed in both the pineal organ and the lateral eyes and the importance of environmental factors in their control remain to be determined and need further investigations.

Age Factors↗

Changes in the lateral filament spacing of skinned muscle fibres when cross-bridges attach.

When a skinned fibre prepared from frog skeletal muscle goes from the relaxed to the rigor state at a sarcomere length of about 2.2 micron, the 1, 0 transverse spacing of the filament lattice, measured by X-ray diffraction, decreases by about 11%. In measurements at various sarcomere lengths, the decrease in the spacing was approximately proportional to the degree of overlap between the thick and thin filaments. This suggests that the shrinkage of the lattice is caused by a lateral force produced by cross-bridges. In order to estimate the magnitude of the lateral force, the decrease of spacing between relaxed and rigor states was compared with the shrinkage caused osmotically by adding a high molecular weight polymer, polyvinylpyrrolidone, to the bathing solution. The results indicate that the lateral force produced per unit length of thick filament in the overlap zone is of the same order of magnitude as the axially directed force produced during maximum isometric contraction (10(-10) to 10(-9) N/micron). Experiments in the presence of a high concentration of polyvinylpyrrolidone (100 g/l) show that when the lattice spacing is decreased osmotically beyond a certain value, the lateral force produced when the fibre goes into rigor changes its direction, causing the lattice to swell. This result can be explained by assuming that there is an optimum interfilament spacing at which the cross-bridges produce no lateral force. At other spacings, the lateral force tends to displace the filament lattice toward that optimum value.

Animals↗

Practical evaluation of the lateral temporomandibular joint radiograph.

The reevaluation of the lateral transcranial radiograph is needed because of the confusion that surrounds the diagnosis and treatment of TMJ dysfunction-pain. The lack of universal acceptance of the validity of the lateral TMJ radiograph contributes to the lack of progress of TMJ dysfunction-pain treatment and improved methods for the treatment of prosthodontic patients. The lateral transcranial TMJ radiograph was reevaluated for its duplicability (+/- 0.2 mm). The image was found to be a cross section of the lateral third of the condyle rather than a composite view of the condyle made at an angle. The condylar position in the fossa can be correctly evaluated in transcranial radiographs, because the relative condylar position in the fossa is similar in all sagittal views and the image is always of the same sagittal plane (lateral third). Soft tissue within or lining the fossa does not affect the evaluation of condylar position. Chronic osteoarthritic TMJ pathology can exist without subjective pain; therefore, routine use of initial TMJ radiographs with subsequent radiographs at 5-year intervals is suggested for all patients. Because condylar repositioning may be indicated before subjective pain symptoms appear, condylar repositioning should be contemplated whenever extensive prosthodontic treatment is needed. In addition, if chronic osteoarthritic lesions are observed initially, radiographs are indicated at more frequent intervals and anti-inflammatory agents should be considered for routine use depending on the rate and extent of the pathologic development. The existence of osteoarthritic lesions was confirmed by serial radiographs over 5 to 10 years. If an osteoarthritis is present, condylar repositioning (when condylar displacement is present) or changes in occlusion should be considered. There is some clinical evidence that condylar displacement is associated with pathologic remodeling and/or osteoarthritic lesions of the condyle and that condyle repositioning arrests the pathologic process. The principle of condylar concentricity , previously established for the treatment of TMJ dysfunction-pain syndrome and for functional centric relation in prosthodontics, was formulated by associating condylar position in the fossa with TMJ dysfunction-pain in many patients. This article suggests the value of the lateral TMJ radiograph as an important practical aid in the diagnosis and treatment of TMJ dysfunction pain and in the establishment of functional centric relation in prosthodontics.

Cartilage, Articular↗