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PubMed2005

Nitrogen removal in laboratory model leachfields with organic-rich layers.

Septic system leachfields can release dissolved nitrogen in the form of nitrate into ground water, presenting a significant source of pollution. Low cost, passive modifications, which increase N removal in traditional leachfields, could substantially reduce the overall impact on ground water resources. Bench-scale laboratory models were constructed to evaluate the effect of placing an organic layer below the leachfield on total N removal. The organic layer provides a carbon source for denitrification. Column units representing septic leachfields were constructed with sawdust-native soil organic layers placed 0.45 m below the influent line and with thicknesses of 0.0, 0.3, 0.6, and 0.9 m. Using a synthetic septic tank effluent, NO(3)-N concentrations at 3.8 m below the influent line were consistently below 1 mg L(-1) during 10 months of operation compared with a NO(3)-N concentration of nearly 12 mg L(-1) in the control column. The average total N removal increased from 31% without the organic layer to 67% with the organic layer. Total N removal appeared limited by the extent of organic N oxidation and nitrification in the 0.45-m aerobic zone. Design modifications targeted at improving nitrification above the organic layer may further increase total N removal. Increased organic layer thicknesses from 0.3 m to 0.9 m did not significantly improve average total N removal, but caused a shift in residual nitrogen from organic N to ammonia N. Results indicate that addition of a layer of carbon source material at least 0.3 m thick below a standard leachfield substantially improves total N removal.

Ammonia↗
PubMed1982

Cell differentiation, protein synthesis rate and protein accumulation in muscle cell cultures isolated from embryos of layer and broiler chickens.

Muscle cell cultures were prepared from the leg muscle of 12-d layer and broiler chicken embryos. Cultures were then compared over a 10-d period from their capacity to differentiate into multinucleated myotubes and to synthesize and accumulate protein. Differentiation was qualitatively similar in the two cell types as evidenced by myoblast fusion that occurred rapidly during the first 2 d and remained essentially constant between d 3 and 10. However, several quantitative differences were observed. Even though the number of myotubes per culture was comparable between layers and broilers throughout development, layer muscle cultures usually exhibited a higher percentage fusion and more myonuclei per culture than broiler muscle cultures. Additionally, the nuclear density (i.e., the number of nuclei per myotube segment) was approximately 25% greater in layer cultures than in broilers between d 2 and 10 in culture. The rate of incorporation of 3H-leucine into total protein during pulse labeling experiments was comparable in muscle cultures of layers and broilers; however, broiler muscle cells accumulated approximately 40% more total protein per nucleus between d 6 and 10. Myosin heavy chain synthesis rate was higher in layer than in broiler muscle cultures, but broiler muscle cultures accumulated approximately 30% more myosin heavy chain than layers between d 6 and 10. The half-life of myosin heavy chain was 45 h in layer muscle cultures and 103 h in broiler muscle cultures. Thus, the capacity of broiler cells to accumulate more muscle protein was primarily due to a drastically slower protein breakdown rate.

Animals↗
PubMed1990

[Epidermal growth factor in cholesteatoma--the second report: the localization in the horny layer].

The localization of epidermal growth factor (EGF) in human cholesteatoma tissue, normal ear drum and external auditory canal skin was examined immunohistochemically, using avidin-biotin peroxidase complex method. Bouin-fixed tissue was stained for investigation of horny layer in the epidermis, because fixation in Bouin's solution provides better preservation of the antigen. In the horny layer of cholesteatoma tissue, 19 out of 24 cases had EGF-positive immunoreactivity (79%). In 2 cases of normal external auditory canal skin, 4 cases of normal ear drum and a case of postauricular skin, no EGF-immunoreactivity was revealed in the horny layer. EGF was assayed in the debris of cholesteatoma and the horny layer of the normal bony external canal with dot blot immunoassay. EGF content of the debris was higher than that of the horny layer of normal skin. The result of the first report suggests the activity of cholesteatoma exists in the subcutaneous tissue (see the previous paper). In this report EGF content of cholesteatoma in the horny layer was found higher than that of normal external skin. This result demonstrates that EGF in the horny layer plays an important role in accelerating the growth and bony destruction in cholesteatoma. To summarize these two reports, the following conclusion was reached. In the epidermis EGF content is equal in cholesteatoma and normal skin. But in the subcutaneous tissue and the horny layer EGF content of cholesteatoma is higher than that of normal skin. EGF in situ may be strongly related to the growth and bony destruction of cholesteatoma.

Adolescent↗
PubMed2000

Effect of the adhesive layer thickness on the fracture toughness of dental adhesive resins.

We investigated how the thickness of an adhesive layer between two Co-Cr alloy plates affected the mode I fracture toughness of dental adhesive resin by varying the type of resin using a double cantilever beam (DCB) test. Two typical adhesive resins (PV and SB) were used. The adhesive layers of the DCB test specimens were 20, 100 and 200 microns thick. The fracture modes of PV differed with the thickness of the adhesive layer, such as interface fracture at 20 microns thickness, and similar cohesive fracture at 100 and 200 microns thickness. In the case of SB, crack-propagating areas were observed as cohesive fractures in all test specimens with different adhesive layer thickness, and the surfaces of these areas became remarkably rougher as the thickness of the adhesive layer increased. The fracture toughness of PV was not affected by the differences in thickness between the 100 and 200 microns adhesive layers, but there was a notable decrease in fracture toughness when the adhesive layer decreased to a thickness of 20 microns. That of SB showed a tendency to increase as the adhesive layer became thicker.

Adhesiveness↗
PubMed1989

Layered structure of cast titanium surface.

The present study concerns the surface layered structure of the cast Ti. A commercial Ti was cast into a mold which was made of a phosphate-bonded Al2O3/SiO2 investment. Elemental analyses of the interfacial zone of the casting were made under an electron probe micro-analyzer. The interfacial zone was composed of four layers: the outermost reaction or casting burn layer, the second layer of an O-and Al-stabilized alpha case, the third layer in which Si, P, O, and C were inhomogeneously concentrated, and the fourth layer which consisted of acicular or plate-like crystals. It was observed that the larger the cast volume and the higher the mold temperature, the thicker became each layer and the coarser became the acicular grains. Probably, the layered structure was formed through decomposition of reducible species in the burnout investment and diffusion of the resulting elements into the casting.

Dental Casting Investment↗
PubMed1999

Direct connections between dendritic terminals of tectal ganglion cells and glutamate-positive terminals of presumed optic fibres in layers 4-5 of the optic tectum of Gallus domesticus. A light- and electron microscopic study.

The principal afferent fibres of the avian optic tectum are the optic fibres of retinal origin. They terminate on the contralateral side, in the external layers (2-7) of the optic tectum (called optic layers) turning into these layers from the external surface. The terminal branchings of the optic fibres develop four densely innervated areas in layers 2, 3, 4-5 and 7. Their terminals are large and of various appearance in the different areas. In the middle third of the optic layer (in layers 4-5), thin dendritic terminal sections of tectal ganglion cells (according to Ramòn y Cajal) of layer 13 terminate into bunches. Phaseolus vulgaris lectin immunotracer corroborates these dendritic endings (further: dendritic terminals) of tectal ganglion cells. The direct connections between these dendritic terminals and the supposed optic fibres were studied under electron microscope and it was found that the large terminals of optic fibres containing round synaptic vesicles establish asymmetrical synapses with several dendritic profiles, among them Phaseolus lectin labelled dendritic terminals of ganglion cells. This result morphologically supports the former physiological observation of a direct synaptic transmission between optic fibres and ganglion cells of layer 13. In addition, on the dendritic terminals of ganglion cells, symmetrical synapses established by GABA-positive terminals were found. The optic terminals, the GABA-immunopositive terminals and the dendritic terminals of ganglion cells form complex synaptic units surrounded with glial sheath, and thus they establish glomerulus-like synaptic units. The size of the dendritic tree and the branching pattern of the dendrites of ganglion cells point to divergence and convergence in visual transmission.

Animals↗
PubMed2000

Phospholipids in dialysate and the peritoneal surface layer.

Dialysate concentration of phospholipids has been used to monitor peritoneal membrane status. However, we recently found that the peritoneum has a surface layer in which phospholipids may be the main constituent. Therefore, in this study, we compared the phospholipids composition of peritoneal dialysate and of the peritoneal surface in rats. Eight male Sprague-Dawley rats were used in the study. Five rats received an intraperitoneal injection of 25 mL 4.25% glucose dialysis solution. After four hours, the rats were killed, and the dialysate was drained completely. Then 20 mL of Folch solution was infused into the peritoneal cavity for 30 seconds and drained completely. The other three rats received the Folch solution without dialysis. The effluent and Folch solution were then processed for phospholipids analysis using high performance thin-layer chromatography (HPTLC). The total phospholipids content was ten times higher in the surface layer than in the dialysate effluent. In the effluent, four clearly different components were seen: lysophosphatidylcholine (LPC), sphingomyelin (SM, 29%), phosphatidylcholine (PC, 66%), and phosphatidylinositol (PI, 4.5%). However, in the surface layer, as well as LPC, SM (20.6%), PHC (47%), and PI (6.3%), two additional components were seen, phosphatidylserine (PS, 17.1%) and phosphatidylethanolamine (PE, 8.9%). The quantity of phospholipids in the peritoneal surface of non dialyzed rats was similar to the total quantity of phospholipids (in effluent and in the peritoneal surface) of dialyzed rats. Our results suggest that: (1) a surface layer is present on the peritoneum; this layer could well be extracted by Folch solution; and, with appropriate incubation time, one can separate the surface layer without damaging the mesothelial cells; (2) the composition of phospholipids in the effluent is different from that in the peritoneal surface layer, which contains membrane phospholipids (PS and PE); (3) shielding from the peritoneal surface may be the main reason for the presence of phospholipids in the dialysate.

Animals↗
PubMed2001

[Analysis of aged-related nerve fiber layer thickness changes with laser polarimetry].

PURPOSE: Scanning laser polarimetry allows a quantitative study of the retinal nerve fiber layer thickness. It was used to evaluate the effects of aging on thickness of nerve fiber layer in the retinal of normal subjects. METHODS: The retinal nerve fiber layer thickness of 48 eyes of 48 normal subjects was studied. Three consecutive polarimetric images were acquired for each eye and the mean image was calculated, the nerve fiber layer thickness measurements was obtained in this image using the standard 10 pixels and 1.75 disc diameter band centered on the optic nerve head. The standard GDx quadrants were used. Linear regression analysis was used to evaluate the effects of aging on the nerve fiber layer thickness. RESULTS: The mean nerve fiber layer thickness was 78.59 SD 9.81 microm. A significant reduction with age was found in the mean nerve fiber layer thickness (r2: 0.19, p=0.002), the mean superior-inferior quadrant thickness (r2: 0.239, p<0.001), the superior (r2: 0.212; p=0.001) and inferior quadrant thickness (r2: 0.196, p= 0.002), and the maximal superior quadrant (r2: 0.111, p= 0.019) and inferior quadrant thickness (r2: 0.081, p=0,048). CONCLUSIONS: The nerve fiber layer thickness decreases with increasing age in normal subjects.

Adolescent↗
PubMed2001

Effectiveness of thin-layer preparations vs. conventional Pap smears in a blinded, split-sample study. Extended cytologic evaluation.

OBJECTIVE: To further evaluate the effectiveness of the AutoCyte PREP thin-layer slide preparation (TriPath Imaging, Inc., Burlington, North Carolina) as compared to conventional Pap smears. STUDY DESIGN: A split-sample, blinded evaluation of matched thin-layer preparations and conventional smears from 2,438 patients was performed. This material was enriched by including 260 cases of high grade squamous intraepithelial lesions (HSILs) and cancer cases from an earlier study. Many of these cases were difficult to diagnose, containing very few abnormal cells on one or both matching slides. The preparations were evaluated multiple times by both thin-layer-inexperienced and -experienced cytology professionals to better compare performance related to preparation quality alone. RESULTS: The initial evaluations of the slides by personnel with only brief training in thin-layer interpretation demonstrated equivalent performance for the two preparations. The reevaluation study by cytology professionals with several months of thin-layer experience demonstrated a statistically significant improvement in detection of both LSIL and HSIL lesions using AutoCyte PREP slides. There was also a statistically significant improvement in the number of satisfactory samples using the AutoCyte PREP method. CONCLUSION: The study demonstrated that the AutoCyte PREP thin-layer slide preparation is at least equivalent to conventional Pap smears in the detection of LSIL and HSIL, even when evaluated by cytology professionals who have been newly trained in the thin-layer method and that, with increased experience, the thin-layer AutoCyte PREP slide preparation method showed a statistically significant improvement in disease detection.

Female↗
PubMed2001

[A study on susceptibility of different layers of rabbit retina to ocular hypertension].

OBJECTIVE: To investigate the histological damage and its degrees of different layers of rabbit retina induced by ocular hypertension. METHODS: The intraocular pressure (IOP) was elevated by intracameral injection of 0.10 - 0.15 ml of 2% methylcellulose in sixteen gray rabbits. The rabbit eyes were enucleated, fixed, and paraffin-embedded. For histological evaluation, the slides were stained with hematoxylin-eosin, examined by light microscopic and computer automatic image analysis. RESULTS: The quantitative analysis indicated that all of the retinal layers have different degrees of histopathological damage. Among them, the retinal ganglion cells (RGCs) and retinal nerve fiber layer (RNFL) were most severely damaged, with the decrease rate of 74.3% and 61.9%, respectively. The decrease rates of other retinal layers were as follows: the retinal inner layer, 42.4%; the whole sensory layer of the retina, 35.0% and the outer layer, 24.2%. We also found a significant correlation between RGCs loss and RNFL thinning (r = 0.68, P < 0.01), demonstrating a strong correlation between IOP level and RNFL thickness (F = 8.97, P < 0.01). CONCLUSION: All of the anatomic layers of retina can suffer from degeneration and atrophy at different degrees.

Animals↗
PubMedDate not supplied

Peripapillary nerve fiber layer thickness measurement reproducibility using optical coherence tomography.

OBJECTIVE: To assess reproducibility of quadrantic and clock hour sectors of retinal nerve fiber layer thickness in normal eyes using optical coherence tomography. MATERIALS AND METHODS: Normal eyes of healthy volunteers meeting eligibility criteria were imaged by two inexperienced operators. Six 360 degrees circular scans with a diameter of 3.4 mm centered on the optic disc were obtained during each scanning session, and a baseline image was formed using 3 high-quality images defined by the software. Images were obtained on three different days within a 4-week period. Variance and coefficient of variation (CV) were calculated for quadrantic and retinal nerve fiber layer clock hour sectors obtained from the baseline image. RESULTS: Five normal eyes were scanned. Intraoperator reproducibility was high. The mean (+/- SD) CV for total retinal nerve fiber layer thickness was 5.3 +/- 3.82% and 4.33 +/- 3.7% for operators 1 and 2, respectively. Interoperator reproducibility was good with statistically similar variance for all quadrantic and clock hour retinal nerve fiber layer parameters (P = .42 to .99). The nasal retinal nerve fiber layer was the most variable sector for both operators (mean CV: 10.42% and 7.83% for operators 1 and 2, respectively). Differences in mean total, nasal, temporal, and superior retinal nerve fiber layer thickness were not statistically significant between operators for all eyes; however, for inferior retinal nerve fiber layer thickness, there was a significant (P = .0007) difference between operators in one eye. CONCLUSION: Peripapillary retinal nerve fiber layer thickness assessments using optical coherence tomography have good intraoperator and interoperator reproducibility. Inexperienced operators can generate useful measurement data with acceptable levels of variance.

Adult↗
PubMed2003

Emergent properties of layer 2/3 neurons reflect the collinear arrangement of horizontal connections in tree shrew visual cortex.

The superficial layers of primary visual cortex, unlike layer 4, have an extensive network of long-range horizontal connections linking sites of similar orientation preference. To identify possible functional consequences of this distinct anatomy, we compared the receptive field properties of layers 2/3 and 4 neurons in tree shrew primary visual cortex with electrophysiological recordings. We found that elongated receptive fields, strong orientation tuning, and length summation (properties predicted by the anatomy of the horizontal connections) are present in layer 2/3 neurons, but not in layer 4 neurons. We further characterized the summation fields of layer 2/3 neurons and found axis and orientation-specific facilitation that matched the distribution of horizontal connections. The functional signature of horizontal connections was also evident in the population response of layer 2/3 neurons; the intrinsic signal activation pattern elicited by an array of collinear Gabor elements was significantly stronger than that elicited by a noncollinear array. Furthermore, our results showed that this enhancement of population response was achieved without compromising spatial resolution along the collinear axis, providing stimulus-specific facilitation without filling in between stimuli. Taken together, these results suggest that horizontal connections play a significant role in shaping the visual responses of layer 2/3 neurons.

Animals↗
PubMed2003

Papanicolaou and thin-layer cervical cytology with colposcopic biopsy control. A comparison.

OBJECTIVE: To compare the accuracy of conventional Papanicolaou and fluid-based, thin-layer cervical cytology. STUDY DESIGN: Cervical cytology was performed in duplicate on women who presented for cervical screening. Papanicolaou and thin-layer (ThinPrep, Cytyc Corp., Boxborough, Massachusetts) cytologic samples were collected simultaneously using a split-sample method. Cytologic slides were read and reported independently. Clinical follow-up was based on the most abnormal result. Colposcopy was performed as clinically indicated, and biopsy results were compared with cytologic diagnoses. RESULTS: Three thousand samples were compared. Papanicolaou and thin-layer results were significantly different (P = .0001), with identical diagnoses in 1,844 (61%) of patients. Eighty thin-layer (2.7%) and 177 Papanicolaou (5.9%) samples were read as limited or unsatisfactory (P < .0001). The rates of atypical squamous cells of undetermined significance (ASCUS) were not statistically different (P = .06). Thin-layer cytology was read more often as low grade squamous intraepithelial lesion (P = .001) or high grade squamous intraepithelial lesion (P = .006). Colposcopy with biopsy was performed on 291 patients. With ASCUS considered an abnormal result, thin-layer cytology was more sensitive (91% vs. 85%) but had lower positive predictive value (69% vs. 74%) than Papanicolaou cytology for the presence of cervical neoplasia. CONCLUSION: Papanicolaou and thin-layer cervical cytology yielded significantly different information. Thin-layer cytology yielded significantly fewer unsatisfactory results and was more sensitive for identifying cervical intraepithelial neoplasia.

Adult↗
PubMed2003

Effect of drying methods on hybrid layer thickness.

PURPOSE: To evaluate the effect of drying methods used in scanning electron microscopy on the thickness of the hybrid layers created by several different adhesive systems. METHODS: A total etch dry bonding system, (Photobond), a three-step bonding adhesive system, (Scotchbond Multi-Purpose), a wet-bonding adhesive system (All-Bond 2) and a self-etching primer system (Mac Bond II) were used in this study. To permit measurement of the thickness of the hybrid layer, the resin-dentin interfaces were polished and etched briefly to remove polishing debris followed by immersion in 10% NaOCl for 4 hours. Half of the specimens in each group were subjected to fixation and critical-point drying followed by gold sputter-coating. The remaining specimens were allowed to air dry prior to gold sputter-coating. SEM observations were carried out to determine the structure and thickness of the hybrid layers. RESULTS: The thickness of hybrid layers were affected by the drying methods with the critical-point drying methods producing the thickest hybrid layers (P < 0.05). The thickest hybrid layers were created by Photobond, with Scotchbond Multi-Purpose and All-Bond 2 producing intermediate thickness hybrid layers, among the total etch systems. The thinnest hybrid layer among all of the adhesive systems was produced by the self-etching primer, Mac Bond II.

Acid Etching, Dental↗
PubMed2004

The comparison of the thickness of the cementum layer in Type 2 diabetic and non-diabetic patients.

It has been suggested diabetes plays an important role in tooth loss. Studies examining the periodontal structures and the alveolar bone architecture in diabetics have revealed some alterations. However, mechanisms responsible for these alterations have not been elucidated completely. Established relationships between the cementum layer, which is resistant to resorption, and diabetes are few in number. The aim of this study was to compare the thickness of the cementum layer in Type 2 diabetic and non-diabetic subjects in order to improve the understanding of dental mobility in Type 2 diabetes and its effect on tooth loss. A total of 46 male patients with a mean age of 61.72 +/- 5.45 yr. were included in this study (Type 2 diabetics, n=23; non-diabetics, n=23); undecayed. Single rooted premolar teeth extracted from 46 male patients were used to assess the alterations in the cementum layer in Type 2 diabetics. Histological preparations from extracted teeth were examined under light microscopy. In each tooth, the thickness of the cementum layer was measured by an oculometer in 4 different sites on the specimen with the largest pulp space including the pulp chamber and root canals. Statistical analyses were performed with student's t test. The average thickness of the cementum layer in the decalcified teeth extracted from non-diabetic patients was compared to the average thickness of the cementum layer in Type 2 diabetic patients. A significant difference was observed in every site of measurement between Type 2 diabetic and non-diabetic patients with regard to the thickness of the cementum layer (p < 0.05). The cementum layer was thicker at the apical part of the root and at the midpoint of the apical half, and thinner at the central part of the root and at the midpoint of the coronal half in Type 2 diabetic patients.

Aged↗
PubMed2004

[Distribution and characters of soil dry layer in north Shaanxi Loess Plateau].

Based on a whole survey and detailed analysis in artificial Robinnia pseudoscacia forestland, distribution and characters of dry layer in soil were studied in north Shaanxi Loess Platea. The results showed that soil dry layer was distributed universally from south to north in Loess Plateau, which can be classified into four zones according to the dryness: 1) In southern gully zone represented by Ziwu Ridge and Huanglong Moutain in Yijun County, the soil dry layer was gentle, so if the appropriate measures were taken and water-saving facility were available or in water-abundant year, the shortage of soil water could be alleviated; 2) In northern gully zone represented by Fuxian and Huangling County, light soil dry layer occurs and was getting worse and we should pay close attention to this; 3) In the large hill and gully zone, serious dry layer appears, it could be subdivided into south, west and north plots. In south plot represented by Yanan and Yanchang County the dry layer was moderate; in west represented by Wuqi and Ansai County the dry layer was severe; in north represented by Suide and Mizhi County the dry layer was disastrous; 4) In the windy sand zone represented by Shenmu County, since the precipitation decreased drastically and seriously sandy, very grave soil desiccation appeared. Also, soil dryness showed apparent horizontal differences with rainfall and the apparent vertical gradient in small hill area.

Ecology↗
PubMedDate not supplied

[Bacterial and archaeal S-layers as object of bionanotechnology].

Many species of Bacteria and Archaea posses a regularly structured surface layers (S-layers) as outermost cell envelope component. S-layers composed of a single protein or glycoprotein species. The individual subunits of S-layers interact with each other and with the supporting bacterial envelope component through non-covalent forces. Pores in the crystalline protein network are with mean diameter of 2-6 nm, the thickness of S-layer is 5-10 nm. The isolated S-layer subunits reassemble into two-dimensional crystalline arrays in solution, on solid supports, on planar lipid films. These unique features of S-layers have led to a broad spectrum applications. This review focuses on the structural properties S-layers and S-proteins and their applications with accent to using this structures in nanobiotechnology.

Archaea↗
PubMed2005

Composite resin layering and placement techniques: case presentation and scientific evaluation.

UNLABELLED: Composite resin technology has evolved, providing clinicians with the ability to deliver more natural-looking restorations for their dental patients. The evolution of layering techniques and internal staining procedures has further improved composite resins' potential for optimal results. This article discusses difficulties associated with traditional composite layering and staining, and it presents in vitro research that supports a novel layering approach. Specifically, the cut-back, etch, bond, and layer technique (CEBL) is introduced as an alternative to freehand layering. LEARNING OBJECTIVES: This article presents current concepts for composite resin layering and bonding technology. Upon reading this article, the reader should: Understand the clinical protocol for resin layering and bonding. Recognize the scientific advantages associated with composite layering with the CEBL technique.

Adult↗