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PubMed2003

Synaptic interactions of late-spiking neocortical neurons in layer 1.

Layer 1 of the neocortex is an important zone in which synaptic integration of inputs originating from a variety of cerebral regions is thought to take place. Layer 1 does not contain pyramidal cells, and several histochemical studies have suggested that most layer 1 neurons are GABAergic. However, although layer 1 neurons could be an important source of inhibition in this layer, the synaptic action of these neurons and the identity of their postsynaptic targets are unknown. We studied the physiological properties and synaptic interactions of a class of cells within layer 1 called late-spiking (LS) cells. The dendrites and axons of layer 1 LS cells were confined primarily to layer 1. Using paired recording, we showed that LS cells formed GABAergic connections with other LS cells as well as with non-LS cells in layer 1 and with pyramidal cells in layer 2/3. We also found that layer 2/3 pyramidal neurons provide excitatory inputs to LS cells. It has been suggested previously that GABAergic neurons belonging to the same class in the cortex are electrically coupled. In agreement with that hypothesis, we found that LS cells were interconnected by electrical coupling (83%), whereas electrical coupling between LS cells and non-LS cells was infrequent (2%). Thus, we provide evidence showing that a group of GABAergic neurons within layer 1 are specifically interconnected by electrical coupling and can provide significant inhibitory inputs to neurons in layer 1 and to distal dendrites of pyramidal cells.

Animals↗
PubMed2000

[A surface reacted layer study of titanium-zirconium alloy after dental casting].

OBJECTIVE: To investigate the influence of the mold temperature on the surface reacted layer of Ti-Zr alloy castings. METHODS: Ti-Zr alloy was casted into a mold which was made of a zircon (ZrO2.SiO2) for inner coating and a phosphate-bonded material for outer investing with a casting machine (China) designed as vacuum, pressure and centrifuge. At three mold temperatures (room temperature, 300 degrees C, 600 degrees C) the Ti-Zr alloy was casted separately. The surface roughness of the castings was calculated by instrument of smooth finish (China). From the surface to the inner part the Knoop hardness and thickness in reacted layer of Ti-Zr alloy casting was measured. The structure of the surface reacted layer was analysed by SEM. Elemental analyses of the interfacial zone of the casting was made by element line scanning observation. RESULTS: The surface roughness of the castings was increased significantly with the mold temperature increasing. At a higher mold temperature the Knoop hardness of the reactive layer was increased. At the three mold temperature the outmost surface was very hard, and microhardness data decreased rapidly where they reached constant values. The thickness was about 85 microns for castings at room temperature and 300 degrees C, 105 microns for castings at 600 degrees C. From the SEM micrograph of the Ti-Zr alloy casting, the surface reacted layer could be divided into three different layers. The first layer was called non-structure layer, which thickness was about 10 microns for room temperature group, 20 microns for 300 degrees C and 25 microns for 600 degrees C. The second layer was characterized by coarse-grained acicular crystal, which thickness was about 50 microns for three mold temperatures. The third layer was Ti-Zr alloy. The element line scanning showed non-structure layer with higher level of element of O, Al, Si and Zr, The higher the mold temperature during casting, the deeper the Si permeating and in the second layer the element Si could also be found. CONCLUSION: The mold temperature is one of the major factors influencing to casting quality. In order to reduce the surface reacted layer of Ti-Zr alloy castings, the lower mold temperature and the investment without Si should be chosen.

Dental Alloys↗
PubMed1991

Micellar subunit assembly in a three-layer model of oligomeric alpha-crystallin.

Differential scanning calorimetry was performed to monitor the heat-induced changes that occur in the structural domain of lens alpha-crystallin. Circular dichroism and fluorescence also were used to resolve the controversial issue of the quaternary structure of alpha-crystallin. Based on the thermal behavior as monitored by these techniques, a model is proposed that can account for all previous data as well as the currently reported thermal data. The proposed model of native alpha-crystallin has a three-layer structure in which the inner layer (core) is a micelle containing 12 subunits arranged in cuboctahedral symmetry. The apolar region is directed inward constituting a hydrophobic core similar to a micelle and adding structural stability. A second layer of six subunits has a similar but not identical structure to the first layer, directing its apolar face toward the hydrophobic core. Thus, these two layers constitute a micelle-like structure with octahedral symmetry. The third layer adds more subunits for a total of not more than 24. Differential scanning calorimetry, circular dichroism, and fluorescence studies indicated that the inner two-layer structure of molecular mass 360 kDa is highly stable and is most likely of the alpha m form. The three-layer structure of the native protein, however, is rather unstable. At 35-45 degrees C the outer layer dissociates from the inner two layers, and at higher temperatures rapidly reassociates to a slightly modified two-layer structure with a stability similar to that of alpha m. The proposed model does not require any specific assembly of the alpha A and alpha B subunits in each layer, but the fluorescence results suggest that the native inner two layers probably contain mostly alpha A.

Animals↗
PubMed1997

Compartmentation of the granular layer of the cerebellum.

Numerous studies have demonstrated that the cerebellum is highly compartmentalized. In most cases, compartmentation involves the Purkinje cells and the molecular layer, but there is also substantial evidence that the granular layer is subdivided into a large number of highly reproducible modules. We first review the evidence for a modular granular layer. Compartmentation of the granular layer has been revealed both functionally and structurally. First, tactile receptive field mapping has revealed numerous discrete functional modules within the granular layer. The molecular correlates of the receptive fields may be the compartments revealed by histological staining of the cerebellum for several enzymes and antigens. The structural substrate of the receptive fields is the mossy fiber afferent projection map, and anterograde tracing of various mossy fiber projections shows afferent terminals in parasagittal bands within the granular layer that are topographically aligned with the Purkinje cell compartments. Based on this evidence we argue that the cerebellum consists of many hundreds of reproducible structural/functional modules, and that a modular organization is a prerequisite for the efficient parallel processing of information during motor control. The complex organization of the adult granular layer implies elaborate developmental mechanisms. In the second part of the review we consider five developmental models to generate the modular organization of the adult granular layer: 1) the external granular layer is heterogeneous, and its topography translates directly into a modular granular layer; 2) granular layer modules are clones, derived from single external granular layer precursors; 3) modules in the granular layers are a secondary epigenetic response to the compartmentation of the Purkinje cells; 4) modules are secondary to the compartmentation of the afferent terminal fields; 5) modules are sculpted by activity-dependent processes.

Adult↗
PubMed2000

An ultrastructural study of the influence of acidity of self-etching primers and smear layer thickness on bonding to intact dentin.

PURPOSE: The objectives of this study were (1) to determine the depth of demineralization into intact dentin using several self-etching primer systems with different pH values, and (2) to evaluate whether hybridization of intact dentin in Clearfil SE Bond may be affected by variation in the thickness of the smear layers. MATERIALS AND METHODS: Dentin disks were created from mid-coronal dentin in extracted, human third molars. Three self-etching primer systems (Clearfil Liner Bond II, Liner Bond 2V, and SE Bond) were applied separately to these disks to evaluate how deep self-etching systems penetrate through smear layers into intact dentin. Dentin treated with All-Bond 2 using the "no-etch" technique was used as a control group. In the second part of the study, dentin disks with different smear-layer thicknesses were produced. The cryofractured control group was devoid of a smear layer. The experimental teeth were ground with 60-, 180-, or 600-grit SiC paper and bonded using SE Bond. Dentin disks were bonded together and examined with TEM. RESULTS: All-Bond 2 did not etch beyond the smear layer. The three self-etching primers etched beyond the smear layer to form true hybrid layers within intact dentin. This layer was thickest with Liner Bond 2 (ca 1.2 to 1.4 microns), but very thin (0.5 micron) using both Liner Bond 2V and SE Bond. Application of SE Bond to dentin of different surface roughness produced hybridized smear layers of variable thickness. However, the thickness of the underlying true hybrid remained consistent for the four groups (ca 0.4 to 0.5 micron). CONCLUSION: Self-etching primers create thin hybrid layers that incorporate the smear layer. The suspicion that thick smear layers may interfere with the diffusion of self-etching primers into the underlying intact dentin was not confirmed.

Acid Etching, Dental↗
PubMed2000

Relationship between different subcutaneous adipose tissue layers, fat mass, and leptin in response to short-term energy restriction in obese girls.

This study addresses whether the expected relationship of 15 specified subcutaneous adipose tissue layers (SAT layers) from 1-neck to 15-calf and body fat mass (FM) with leptin was influenced by a weight-loss program. In 30 obese girls (10 prepubertal, 15 pubertal, and 5 late/postpubertal) SAT layers were measured by means of the optical device Lipometer. Fat mass (FM) was estimated indirectly by means of bioelectrical impedance. Leptin and insulin were determined by means of radioimmunoassays. All measurements were performed before (pre) and after (post) 3 weeks of low-caloric diet and physical training. At the beginning of the study, there were significant correlations for all estimates of adiposity and leptin (0.67 to 0.79; P < 0.0001). Five SAT layers from the upper body and the trunk (0.48 to 0.67; P < 0.01) but none from the abdominal region and lower extremities were correlated with leptin. FM together with SAT layers 4-upper back and 8-lower abdomen (negative slope) explained 79% of the variation in pre leptin values (P < 0.0001). The weight-loss program significantly reduced leptin (P < 0.0001), insulin (P = 0.04), estimates of adiposity (P < 0.0001), and SAT layers 4-upper back (P = 0.0006), 11-front thigh, 13-rear thigh, and 14-inner thigh (P between <0.03 and <0.01). Although significant, the reductions in the four SAT layers were small. Estimated fat-free mass was significantly increased after three weeks (P < 0.05). Changes in SAT layers from the upper extremities and from the trunk were inversely correlated to the decrease in leptin (P between <0.05 and <0.001). Initial leptin was the best correlate of the decrease in leptin (adj. R(2) = 0.815; P < 0.0001). However, when only changes in adiposity and insulin were considered in the regression model, changes in insulin contributed to the fall in leptin (adj. R(2) = 0.23; P = 0.004). When changes in SAT layers were added to the model, changes in SAT layers 2-triceps and 10-hip (negative slopes) contributed to the decrease in leptin (adj. R(2) = 0.48; P < 0.0001). After weight loss, correlations between estimates of post adiposity and post leptin (0.40, P = 0.01 to 0.57, P = 0.0005) were lower compared with pre values. SAT layers 4-upper back and 3-biceps contributed independently to post leptin values (adj. R(2) = 0.50; P < 0.0001). It is suggested that fat mass and SAT layers from the upper body are the main determinants of leptin in obese girls before weight loss. The diet and sports intervention program reduced leptin independent of the reduction in adiposity. The distribution of subcutaneous fat might be a stable correlate of circulating leptin after a short-term reduction in energy intake. Am. J. Hum. Biol. 12:803-813, 2000. Copyright 2000 Wiley-Liss, Inc.

Journal Article↗
PubMed1975

The projections of cells in different layers of the cat's visual cortex.

The projection of cells in different layers of several cortical visual areas in the cat were studied using the method of retrograde transport of horseradish peroxidase. Injections of the enzyme were made through a recording micropipette, making it possible to localize the injection site by physiological criteria. We found that layer VI cells projected to the alteral geniculate nucleus, while a distinct population of cells in layer V projected to the superior colliculus. Cells in layers II and III were tha major sources of ipsilateral cortico-cortical connections. This pattern of projection was consistent from one visual area to another. Pyramidal cells appeared to be the source of cortico-geniculate, cortico-collicular and cortico-cortical projections. The proportion of cells within a layer that terminated in a given site varied from layer to layer: apparently all of the large pyramids in layer V had terminals in the superior colliculus, about half of the pyramids in layer VI had terminals in the lateral geniculate nucleus, while only a small proportion of the pyramids in layers II and III had terminals in any single cortical area. The results indicated a remarkable specificity in the projections of the cortical layers. The cortical connections of the different cell types in layers A and A1 of the lateral geniculate nucleus were also examined: the cells that projected to area 17 were much more numerous and were on the average smaller than those that projected to area 18. Projections to the cortex were also found from the pulvinar, the medial interlaminar nucleus and the posterior nucleus. Direct connections were observed to the lateral geniculate nucleus from several midbrain reticular nuclei. Finally, projections were found to the superior colliculus from the zona incerta, the reticular nucleus of the thalamus and the ventral lateral geniculate nucleus.

Animals↗
PubMed1992

Heterogeneity of layer II neurons in human entorhinal cortex.

Abnormalities in the layer II neurons of human entorhinal cortex have been implicated in the pathophysiology of Alzheimer's disease and schizophrenia. The reported abnormalities are not homogeneously distributed throughout the entorhinal cortex, suggesting that layer II of entorhinal cortex may contain different subpopulations of neurons, each with a different susceptibility to pathological mechanisms. In order to investigate the possible heterogeneity of neurons in layer II of human entorhinal cortex, we first identified distinct subdivisions of human entorhinal cortex by adapting the cytoarchitectonic criteria for subdivisions of monkey entorhinal cortex described by Amaral et al. (J Comp Neurol 264:326, 1987). The morphology and regional distribution of distinct subpopulations of human layer II neurons were determined through the use of immunohistochemical techniques. Multipolar, stellate, and modified pyramidal neurons in the characteristic cell clusters or islands of layer II were immunoreactive for nonphosphorylated neurofilament proteins. The intensity of immunoreactivity for the nonphosphorylated neurofilament proteins gradually increased along the rostrocaudal axis of entorhinal cortex and was primarily due to a similar gradient in the density of labeled neurons per island. The calcium-binding protein calbindin D-28K was found in both pyramidal and nonpyramidal neurons in layers II and superficial III. The distribution of calbindin-immunoreactive neurons also depended upon the region of entorhinal cortex. In rostral entorhinal cortex, labeled neurons were scattered throughout the superficial layers, whereas in caudal entorhinal cortex, distinctive patches of small calbindin-immunoreactive neurons were found among the layer II islands. Another calcium-binding protein, parvalbumin, was present in nonpyramidal neurons in layers II and III that were distinct from those containing calbindin. The regional distribution of parvalbumin-positive neurons was very similar to that of the neurofilament immunoreactive neurons; in rostral entorhinal cortex very few parvalbumin-labeled neurons were present but their frequency gradually increased in the caudal direction. In addition, punctate parvalbumin immunoreactivity was frequently encountered in the location of the nonphosphorylated neurofilament protein-positive layer II islands. These findings demonstrate that layer II of human entorhinal cortex contains distinct subpopulations of neurons, that the relative density of each subpopulation differs across cytoarchitectonic regions, and that the patterns of distribution of these subpopulations are in some cases similar and in other cases complementary. This heterogeneity in the organization of layer II of human entorhinal cortex has important implications for the study of some neuropsychiatric disorders.

Adult↗
PubMed2003

Morphological and numerical analysis of synaptic interactions between neurons in deep and superficial layers of the entorhinal cortex of the rat.

Neurons providing connections between the deep and superficial layers of the entorhinal cortex (EC) constitute a pivotal link in the network underlying reverberation and gating of neuronal activity in the entorhinal-hippocampal system. To learn more of these deep-to-superficial neurons and their targets, we applied the tracer Neurobiotin pericellularly in layer V of the medial EC of 12 rats. Labeled axons in the superficial layers were studied with light and electron microscopy, and their synaptic organization recorded. Neurobiotin-labeled layer V neurons displayed "Golgi-like" staining. Two major cell types were distinguished among these neurons: (1) pyramidal neurons with apical spiny dendrites traversing all layers and ramifying in layer I, and (2) horizontal neurons with dendrites confined to the deep layers. Labeled axons ramified profusely in layer III, superficially in layer II and deep in layer I. Analysis of labeled axon terminals in layers I-II and III showed that most synapses (95%) were asymmetrical. Of these synapses, 56% occurred with spines (presumably belonging to principal neurons) and 44% with dendritic shafts (presumably interneurons). A small fraction of the synapses (5%) was of the symmetrical type. Such synapses were mainly seen on dendritic shafts. We found in two sections a symmetrical synapse on a spine. These findings suggest that the deep to superficial projection is mainly excitatory in nature, and that these fibers subserve both excitation and feed-forward inhibition. There is an additional, much weaker, inhibitory component in this projection, which may have a disinhibitory effect on the entorhinal network in the superficial layers.

Animals↗
PubMed2001

Apoptotic cell death in the mouse retinal ganglion cell layer is induced in vivo by the excitatory amino acid homocysteine.

Homocysteine, an excitatory amino acid and a homolog of cysteine, induces neuronal cell death in brain via stimulation of N-methyl-D-aspartate (NMDA) receptors. It also selectively activates NMDA receptors of retinal ganglion cells, but it is not known if high levels of homocysteine are toxic to these cells. The purpose of this study was to determine whether increased levels of homocysteine caused death of neurons in the ganglion cell layer; if so whether this death occurred via an apoptotic mechanism and to determine the consequences of simultaneous elevation of homocysteine and glutamate, a known retinal excitotoxin, on the viability of neurons of the ganglion cell layer. C57BL/6 mice were injected intravitreally with either homocysteine or glutamate/homocysteine combined (final concentrations: 25, 75, and 200 microM); injection of glutamate (25 and 200 microM) served as a positive control. Eyes were harvested and cryosections prepared 5-6 days post-injection. Systematic morphometric analysis of retinas of mice injected with homocysteine indicated that the total number of cells in the ganglion cell layer decreased by about 23% following exposure to 200 microM homocysteine. To determine whether the neurons of the ganglion cell layer were dying by apoptosis, the TUNEL method was used and was confirmed by immunohistochemical studies of caspase-3, known to be expressed at high levels during retinal ganglion cell apoptosis. Microscopic analysis revealed significantly more TUNEL-positive cells in the ganglion cell layer in homocysteine-injected eyes than in contralateral PBS-injected eyes. Retinas injected with 75 and 200 microM homocysteine displayed significantly more TUNEL-positive neurons in the ganglion cell layer (2 and 2.9, respectively) than PBS-injected retinas (0.25). In eyes injected simultaneously with homocysteine/glutamate, the number of apoptotic cells in the ganglion cell layer almost doubled that for homocysteine or glutamate injections alone. Immunohistochemical analysis of activated caspase-3 revealed numerous positively labelled neurons in the ganglion cell layer in homocysteine and homocysteine/glutamate-injected eyes, but not in PBS-injected eyes. Quantification of this data revealed a significantly greater number of caspase-3-positive neurons in the ganglion cell layer of retinas injected with 75 and 200 microM homocysteine (2.9 and 4.4, respectively) than for PBS-injected retinas (0.5). This confirms that death of neurons in the ganglion cell layer is occurring by apoptosis. The present study provides the first evidence that homocysteine is toxic to neurons of the ganglion cell layer. In addition, it provides evidence that these retinal neurons are dying by apoptosis and it demonstrates for the first time that excitotoxic damage to neurons of the ganglion cell layer is potentiated by simultaneous elevation of homocysteine and glutamate. These findings are relevant to retinal ganglion cell death characteristic of diabetic retinopathy, which is thought to be mediated by overstimulation of the NMDA receptor.

Analysis of Variance↗
PubMed2000

The formation of the chick ileal muscle layers as revealed by alpha-smooth muscle actin immunohistochemistry.

The genesis of intestinal smooth muscle layers was immunohistochemically investigated by use of an antibody to alpha-smooth muscle actin (alpha-SMA) in the developing chick ileum. Myoblast cells positive for alpha-SMA were already found in the presumptive circular muscle layer on E 8.5. On E 11.5 radially oriented muscle fibers were protruded from the outermost layer of the developing circular musculature and then formed a tuft-like aggregates. These radial muscle bundles were bent into an L-shape. The long distal extension of muscle bundles run parallel to the long axis of the ileal loop and developed into the longitudinal muscle layer. The obliquely oriented muscle fibers, locating at the intermuscular space of the muscularis propria, probably are to be considered a remnant of the short extension of radial muscle bundles. The muscularis mucosae was formed by the processes equivalent to the genesis of longitudinal muscle layer. On E 14.5 centripetally oriented muscle fibers emerged from the innermost layer of circular musculature. The long distal extension of centripetal fibers lay along the inner surface of developing circular musculature. On E 19.5 the longitudinal muscle layer of the muscularis mucosae was newly formed by separating from the circular musculature. The villous myoblast cells initially developed from the innermost layer of the muscularis mucosae on E 18.5, and were widely distributed in the lamina propria mucosae on E 20.5. Temporal and chronological pattern in expression of alpha-SMA was observed during the development of the chick intestinal smooth muscle. By E 14.5 the entire layer of the muscularis propria was intensely immunostained for alpha-SMA, but from E 15.5 onward the staining intensity gradually began to decrease from the outer half of the circular musculature. Finally, the immunoreactivity was localized in the inner layer of circular muscle and the longitudinal muscle layer. A possible functional role of this inner layer of circular muscle is discussed.

Actins↗
PubMed2005

Study on orientation of immunoglobulin G on protein G layer.

A comparative study of immunoglobulin G (IgG) immobilization was performed, both on a thiolated protein G layer, where this immobilization was due to affinity binding with an Fc fragment of IgG, and on 11-mercaptoundecanoic acid (11-MUA), where the immobilization was due to chemical bonding. The change of IgG layer formation on the two base layers as a function of the IgG concentration was investigated by surface plasmon resonance (SPR), atomic force microscopy (AFM) in a non-contact mode, and spectroscopic ellipsometry (SE). It was observed that the IgG layer was immobilized more evenly on the thiolated protein G layer than on the 11-MUA layer, based on the SPR measurements. The surface topology analysis by AFM indicated that the IgG layer was immobilized on the protein G layer according to the envelope profile of the base layer. Based on the SE analysis, it was determined that the IgG layer thickness on the thiolated protein G layer increased with increasing IgG concentration. Based on the above analyses, the scheme for orientation of IgG immobilized on the thiolated protein G layer was proposed.

Biosensing Techniques↗
PubMed2006

Biomechanical properties of the layered oesophagus and its remodelling in experimental type-1 diabetes.

Passive biomechanical properties in term of the stress-strain relationship and the shear modulus were studied in separated muscle layer and mucosa-submucosa layer in the oesophagus of normal and STZ (streptozotocin)-induced diabetic rats. The mucosa-submucosa and muscle layers were separated using microsurgery and studied in vitro using a self-developed test machine. Stepwise elongation and inflation plus continuous twist were applied to the samples. A constitutive equation based on a strain energy function was used for the stress-strain analysis. Five material constants were obtained for both layers. The mucosa-submucosa layer was significantly stiffer than the muscle layer in longitudinal, circumferential and circumferential-longitudinal shear direction. The mechanical constants of the oesophagus show that the oesophageal wall was anisotropic, the stiffness in the longitudinal direction was higher than in the circumferential direction in the intact oesophagus (P < 0.001) and in the muscle layer (P < 0.05). Diabetes-induced pronounced increase in the outer perimeter, inner perimeter and lumen area in both the muscle and mucosa-submucosa layer. The growth of the mucosa-submucosa layer (P < 0.001) was more pronounced than the muscle layer (P < 0.05). Furthermore, the circumferential stiffness of the mucosa-submucosa layer increased 28 days after STZ treatment. In conclusion, the oesophagus is a non-homogeneous anisotropic tube. Thus, the mechanical properties differed between layers as well as in different directions. Morphological and biomechanical remodelling is prominent in the diabetic oesophagus.

Animals↗
PubMed2004

Classification of hyper-variable Corynebacterium glutamicum surface-layer proteins by sequence analyses and atomic force microscopy.

The structural S-layer proteins of 28 different Corynebacterium glutamicum isolates have been analyzed systematically. Treatment of whole C. glutamicum cells with detergents resulted in the isolation of S-layer proteins with different apparent molecular masses, ranging in size from 55 to 66 kDa. The S-layer genes analyzed were characterized by coding regions ranging from 1,473 to 1,533 nucleotides coding for S-layer proteins with a size of 490-510 amino acids. Using PCR techniques, the corresponding S-layer genes of the 28 C. glutamicum isolates were all cloned and sequenced. The deduced amino acid sequences of the S-layer proteins showed identities between 69 and 98% and could be grouped into five phylogenetic classes. Furthermore, sequence analyses indicated that the S-layer proteins of the analyzed C. glutamicum isolates exhibit a mosaic structure of highly conserved and highly variable regions. Several conserved regions were assumed to play a key role in the formation of the C. glutamicum S-layers. Especially the N-terminal signal peptides and the C-terminal anchor sequences of the S-layer proteins showed a nearly perfect amino acid sequence conservation. Analyses by atomic force microscopy revealed a committed hexagonal structure. Morphological diversity of the C. glutamicum S-layers was observed in a class-specific unit cell dimension (ranging from 15.2 to 17.4 nm), which correlates with the sequence similarity-based classification. It could be demonstrated that differences in the primary structure of the S-layer proteins were reflected by the S-layer morphology.

Amino Acid Sequence↗
PubMed2006

The lower eyelid retractor consists of definite double layers.

PURPOSE: To examine whether the lower eyelid retractor consists of a single layer or multiple layers. DESIGN: Retrospective clinical case series and dissectional study. PARTICIPANTS: Fifty-one lower eyelid retractors (31 right, 20 left) of 44 patients (ages, 63-95 years) during entropion surgeries and 10 lower eyelids (5 right, 5 left) of 5 Oriental cadavers (73-91 years old at death) were observed macroscopically. Specimens from 20 postmortem lower eyelids of 12 Orientals (11 right, 9 left; 66-96 years old at death) were used for microscopic observations. METHODS: Macroscopically, we bluntly or, in parts, sharply dissected lower eyelid retractors into 2 layers during entropion surgeries. Cadaveric lower eyelids also were used to investigate relationships between the lower eyelid retractor and the Lockwood ligament. Cadaveric lower eyelids with sagittal full-thickness sections of the central part were examined microscopically using Masson trichrome staining. MAIN OUTCOME MEASURES: Anatomical findings in the lower eyelid retractor. RESULTS: Lower eyelid retractors easily were detached into 2 layers. Macroscopically, the anterior layer was defined as a coarse tissue continuing from the Lockwood ligament, which joined with the lower orbital septum, and constituted the lower conjoined fascia. The posterior layer appeared to be a dense fibrous sheet with a lustrous surface. Microscopically, the lower eyelid retractor consisted of a definite double layer. The anterior layer, a coarse fibrous tissue, consisted of the suborbicularis fascial layer, orbital septum, and superficial part of the capsulopalpebral fascia, which continued to the anterior lamellae of the lower eyelids. The posterior layer consisted of dense fibers of the capsulopalpebral fascia with smooth muscle continuing to the tarsus. CONCLUSIONS: The lower eyelid retractor consists of a definite double layer. The posterior dense layer containing smooth muscle is the main tractional component of the lower eyelid retractor.

Aged↗
PubMed1992

Transverse uterine incision closure: one versus two layers.

OBJECTIVE: Closure of a low transverse cesarean incision with one layer of suture results in less operating time, better hemostasis, and less infectious morbidity than a two-layer closure. STUDY DESIGN: At our institution 906 women were randomized to closure of a low transverse cesarean incision with either one continuous layer of a locking No. 1 chromic suture and a CTX needle (n = 457) or two continuous layers of No. 1 chromic suture with the first layer locked (n = 449). The Student t test, chi 2 test of proportion, and Wilcoxon rank sum test were used to compare groups of patients. RESULTS: A one-layer closure required less operative time, 43.8 versus 47.5 minutes (p = 0.0003). Fewer additional uterine hemostatic sutures were required in 369 women in whom either the one- (n = 179) or the two-layer (n = 190) closure did not achieve hemostasis (p = 0.046). Endometritis was similar in both groups, 83 (22%) in the one-layer group versus 65 (18%) in the two-layer group (p = 0.17). In no outcome assessment was the two-layer closure superior to the one-layer closure. CONCLUSION: We recommend a one-layer closure when its use is anatomically feasible.

Adult↗
PubMed1999

Stabilizing effect of an S-layer on liposomes towards thermal or mechanical stress.

Isolated subunits of the crystalline cell surface layer (S-layer) protein of Bacillus stearothermophilus PV72/p2 were recrystallized on positively charged unilamellar liposomes. Liposomes were composed of dipalmitoylphosphatidylcholine (DPPC), cholesterol and hexadecylamine (HDA) in a molar ratio of 10:5:4 and they were prepared by the dehydration-rehydration method followed by an extrusion procedure. The S-layer protein to DPPC ratio was 5.7 nmol/micromol which approximately corresponds to the theoretical value estimated by using the areas occupied by the S-layer lattice and the lipid membrane. Coating of the positively charged liposomes with S-layer protein resulted in inversion of the zeta-potential from +29.1 mV to -27.1 mV. Covalent crosslinking of the recrystallized S-layer protein was achieved with glutaraldehyde. Chemical analysis revealed that almost all amino groups (>95%) from HDA in the liposomal membrane were involved in the reaction. To study the influence of an S-layer lattice on the stability of the liposomes, the hydrophilic marker carboxyfluoresceine (CF) was encapsulated and its release was determined for plain and S-layer-coated liposomes in the course of mechanical and thermal challenges. In comparison to plain liposomes, S-layer-coated liposomes released only half the amount of enclosed CF upon exposure to shear forces or ultrasonication as mechanical stress factors. Furthermore, temperature shifts from 25 degrees C to 55 degrees C and vice versa induced considerably less CF release from S-layer-coated than from plain liposomes. A similar stabilizing effect of the S-layer lattice was observed after glutaraldehyde treatment of plain and S-layer-coated liposomes.

Bacterial Proteins↗
PubMed2002

Immunological differences between layer- and broiler-type chickens.

In commercial poultry husbandry, alternatives for the use of antibiotics and vaccines are under investigation, which preferably have to be applicable for both layer- and broiler-type chickens. There are indications that the defense mechanisms vary between layer- and broiler-type chickens. Therefore, the difference in immune response between layer- and broiler-type chickens of the same age was investigated, using TNP-KLH (trinitrophenyl-conjugated keyhole limpet hemocyanin) as antigen without adjuvant. First different routes of immunization (intravenously, intramuscular, subcutaneous and ocular) were examined to find out which immunization route gives the highest antibody titers. The intravenous immunization route resulted in higher TNP-specific antibody responses than the other immunization routes tested and therefore this immunization route was used in both following experiments. In order to investigate the optimal dose of antigen needed for immunization, a dose-response curve in broiler- and layer-type chickens was completed. The humoral immune response was measured in serum by a TNP-specific ELISA and the in vitro cellular immune response by an antigen-specific lymphocyte proliferation assay. The antibody response of layer- and broiler-type chickens appeared to differ, not only in optimal dose and response, but also in kinetics of the response itself. Broiler chickens generated higher IgM anti-TNP titers whereas layer-type chickens generated higher IgG anti-TNP titers. This specific antibody response in broiler-type chickens did not last as long as in layer-type chickens. The TNP-specific cellular immune response was detectable in layer-type chickens, but not in broilers. Both types generate a non-specific cellular immune response, although this response in broilers is lower than in layer-type chickens. From these results, we conclude that broilers primarily respond to TNP-KLH with a high IgM antibody response whereas layer-type chickens respond with a high IgG response. In addition, the cellular response of layer-type chickens is much higher than the response of broilers. The results suggest that broilers are specialized in the production of a strong short-term humoral response and layer-type chickens in a long-term humoral response in combination with a strong cellular response, which is in conformity with their life expectancy.

Animals↗