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PubMed2000

The relationship between different subcutaneous adipose tissue layers, fat mass and leptin in obese children and adolescents.

We studied the relationships of subcutaneous adipose tissue layers (SAT-layers), body fat mass (FM) and waist-to-hip ratio (WHR) with leptin in obese children and adolescents. Twenty-nine obese children and adolescents (12 boys: age: 11.3 +/- 3.7 yr; body mass index [BMI]: 28.5 +/- 4) and 17 girls (age: 12.2 +/- 2.2 yr; BMI: 29.8 +/- 4.7) (mean +/- SD) were studied. FM was estimated by bioelectrical impedance. SAT-layers were determined at 15 different body sites from 1-neck to 15-calf by the Lipometer optical device. Leptin and insulin were determined by RIA. Maturity was associated with a greater thickness of certain SAT-layers from the upper body and with a lower thickness of SAT-layers from the abdominal region and lower extremities. Significant correlations were found for all estimates of adiposity and leptin (all p<0.001). Waist and hip circumferences were not correlated to leptin after adjustment for FM. SAT-layers from the upper body were significantly and positively correlated to leptin. Multiple regression analysis revealed FM as a main contributor to the variation in leptin (R2=0.53, p<0.0001). FM together with SAT-layers 5-front chest and 13-rear thigh explained 72% of the variation in leptin (p<0.0001). In a body fat distribution model, hip circumference together with SAT-layers 4-upper back and 2-triceps explained 75% of the variation in leptin (p< 0.0001). The results suggest that SAT-layers and their topography are main determinants for leptin in obese children and adolescents. Maturity in obese children is associated with higher values of upper body SAT-layers and lower values of abdominal and lower extremities SAT-layers. Whether leptin is under the control of certain subcutaneous adipose tissue depots from the upper body remains to be elucidated by longitudinal studies.

Adipose Tissue↗
PubMed1981

Further studies on the size specificity of commissural projecting neurons of layer III in areas 17, 18, 19 and the lateral suprasylvian area of the cat's visual cortex.

After injection of horseradish peroxidase (HRP) into the commissural area in the border region between areas 17 and 18, the lateral part of area 19 and the lateral suprasylvian area (LS) of cat's visual cortex, HRP-labeled neurons were distributed preferentially in layer III in each cortical region of the other hemisphere. Layer I was free from labeling in each cortical region. There were some real differences in the distribution of labeled neurons in other layers. In the area 17/18 border region, a significant population of labeled neurons was found in the upper layer IV. The labeling of neurons in deeper layers (V and VI) increased in area 19 and further in the LS. There was no great difference in the laminar distribution between neurons which appeared after HRP injections into the homotopical region and those after heterotopical injections on the other side. The commissural area, 17/18 border region and the LS, contained in layer III a larger number of medium-sized to large neurons than acommissural area 17 on the splenial gyrus, where layer III was filled with densely packed small neurons. The size distribution of layer III was unimodal with a marked skew towards the larger value in each cortical region. About 50% of labeled neurons in layer III were distributed in a narrow range at the border of two categories of cell sizes, viz small and medium-sized to large. Among the labeled neurons in layer III, 34.2-47.1% had larger cell sizes. Some of the smallest neurons in layer III were also labeled, however, they appeared only after HRP injections into the homotopical region of the cerebral cortex on the opposite side.

Animals↗
PubMed2005

Histochemical structure of the mucus gel layer coating the fecal surface of rodents, rabbits and humans.

The aim of this study was to investigate whether a mucus layer covers the surface of various animal feces and, if so, to show the structure and mucin composition of this layer. The freshly excreted feces of mice, rats, guinea pigs, rabbits and humans were fixed with Carnoy solution. Cross-sections approximately 5 microm thick were stained with alcian blue (AB) or the periodic acid Schiff (PAS) reaction. We measured the thickness of the mucus layer on the fecal surface of these sections. The fecal surface was covered with a continuous mucus layer in all specimens. The mucus layers of mice, rats and humans consisted of the alternate stratification of AB-positive and PAS-positive mucin layers. In contrast, the mucus layer consisted of an inner PAS-positive neutral mucin layer and an outer AB-positive acidic mucin layer in guinea pigs and rabbits. The average thicknesses of the mucus layers upon the fecal surfaces for mice, rats, guinea pigs, rabbits and humans were 19 +/- 12, 22 +/- 14, 15 +/- 4.6, 19 +/- 14 and 17 +/- 11 microm, respectively. These results demonstrated that the fecal surfaces are covered with continuous mucus layers in rodents, rabbits and humans, with substructures varying among species.

Adult↗
PubMed2000

Columnar organization of dendrites and axons of single and synaptically coupled excitatory spiny neurons in layer 4 of the rat barrel cortex.

Cortical columns are the functional units of the neocortex that are particularly prominent in the "barrel" field of the somatosensory cortex. Here we describe the morphology of two classes of synaptically coupled excitatory neurons in layer 4 of the barrel cortex, spiny stellate, and star pyramidal cells, respectively. Within a single barrel, their somata tend to be organized in clusters. The dendritic arbors are largely confined to layer 4, except for the distal part of the apical dendrite of star pyramidal neurons that extends into layer 2/3. In contrast, the axon of both types of neurons spans the cortex from layer 1 to layer 6. The most prominent axonal projections are those to layers 4 and 2/3 where they are largely restricted to a single cortical column. In layers 5 and 6, a small fraction of axon collaterals projects also across cortical columns. Consistent with the dense axonal projection to layers 4 and 2/3, the total number and density of boutons per unit axonal length was also highest there. Electron microscopy combined with GABA postimmunogold labeling revealed that most (>90%) of the synaptic contacts were established on dendritic spines and shafts of excitatory neurons in layers 4 and 2/3. The largely columnar organization of dendrites and axons of both cell types, combined with the preferential and dense projections within cortical layers 4 and 2/3, suggests that spiny stellate and star pyramidal neurons of layer 4 serve to amplify thalamic input and relay excitation vertically within a single cortical column.

Animals↗
PubMed2001

Loss and atrophy of layer II entorhinal cortex neurons in elderly people with mild cognitive impairment.

Layer II of the entorhinal cortex contains the cells of origin for the perforant path, plays a critical role in memory processing, and consistently degenerates in end-stage Alzheimer's disease. The extent to which neuron loss in layer II of entorhinal cortex is related to mild cognitive impairment without dementia has not been extensively investigated. We analyzed 29 participants who came to autopsy from our ongoing longitudinal study of aging and dementia composed of religious clergy (Religious Orders Study). All individuals underwent detailed clinical evaluation within 12 months of death and were categorized as having no cognitive impairment (n = 8), mild cognitive impairment (n = 10), or mild or moderate Alzheimer's disease (n = 11). Sections through the entorhinal cortex were immunoreacted with an antibody directed against a neuron-specific nuclear protein (NeuN). Stereological counts of NeuN-immunoreactive stellate cells, their volume, and the volume of layer II entorhinal cortex were estimated. Cases exhibiting no cognitive impairment averaged 639,625 +/- 184,600 layer II stellate neurons in the right entorhinal cortex. Individuals with mild cognitive impairment (63.5%; p < 0.0003) and mild or moderate Alzheimer's disease (46.06%; p < 0.0017) displayed significant losses of layer II entorhinal cortex neurons relative to those with no cognitive impairment but not relative to each other (p > 0.33). There was also significant atrophy of layer II entorhinal cortex neurons in individuals with mild cognitive impairment (24.1%) and Alzheimer's disease (25.1%). The volume of layer II was also reduced in individuals with mild cognitive impairment (26.5%), with a further reduction in those with Alzheimer's disease (46.4%). The loss and atrophy of layer II entorhinal cortex neurons significantly correlated with performance on clinical tests of declarative memory. Atrophy of layer II entorhinal cortex and the neurons within this layer significantly correlated with performance on the Mini Mental Status Examination. These data indicate that atrophy and loss of layer II entorhinal cortex neurons occur in elderly subjects with mild cognitive impairment prior to the onset of dementia and suggests that these changes are not exacerbated in early Alzheimer's disease.

Aged↗
PubMed2001

Neocortical cell migration: GABAergic neurons and cells in layers I and VI move in a cyclin-dependent kinase 5-independent manner.

The adult mammalian cerebral cortex arises from a complex series of neuronal migrations. The primitive layer known as the preplate is split into an outer marginal zone and an inner subplate by invading cortical plate neurons in an "inside-out" pattern of layering with respect to time of neuronal origin. In cyclin-dependent kinase 5 (Cdk5)-deficient mice (cdk5(-/-)), the earliest born cortical neurons split the preplate, but later born neurons arrest below the subplate, resulting in an ectopic "outside-in" layer of neurons normally destined for layers II-V. We have pursued this analysis in cdk5(-/-) <--> wild-type chimeric mice coupled with experiments in cell culture. In vitro migration assays show no difference in migrational ability between embryonic cdk5(-/-) and wild-type neurons. In cdk5(-/-) chimeras, layers I and VI are made up of both mutant and wild-type genotype neurons, whereas layers II-V contain predominantly wild-type cells. In addition, a thin layer of neurons is found below layer VI, made up of cdk5(-/-) cells; bromodeoxyuridine labeling suggests that these neurons were destined for layers II-V. Scattered cdk5(-/-) cells are found throughout layers II-V, but these neurons are always found to be GABAergic. The findings suggest that Cdk5 is not required for migration of either the deepest cortical plate neurons or the GABAergic neurons from the ganglionic eminences. The migration of layer II-V pyramidal neurons, however, is intrinsically blocked by Cdk5 deficiency, thus suggesting that different neuronal cell types use distinct mechanisms of migration.

Animals↗
PubMed1988

The effect of altered neuronal activity on the development of layers in the lateral geniculate nucleus.

The main objective of this study was to examine the role of neural activity in the development of cell layers in the dorsal lateral geniculate nucleus (LGN). We studied this relationship in postnatal tree shrews either by completely blocking retinal ganglion cell activity with TTX or by selectively blocking activity to the developing ON-center LGN layers (1 and 2) with 2-amino-4-phosphonobutyric acid (APB), using unilateral and bilateral eye injections. All manipulations were carried out from birth (P0), when no LGN cell layers are evident, to or past the point when layers are recognizable (i.e., 1-2 weeks). Nissl-stained and cytochrome oxidase (CO)-reacted material was examined for all cases. Our results show that in the absence of activity produced by bilateral TTX injections, interlaminar spaces between cell layers do begin to develop. Retinal afferents, which are segregated at birth, remain segregated, and differential CO staining between matched sets of LGN layers is evident. The normal pace of LGN development, however, is slowed significantly: LGN cells are smaller and interlaminar spaces are narrower than are seen in age-matched controls. Unilateral TTX injections produce similar, but more dramatic and asymmetric, effects on LGN cells, perhaps because cells are at a competitive disadvantage relative to their normally innervated counterparts in cortex. Combining unilateral eye enucleation at P0 with subsequent TTX treatment of the other eye clearly demonstrates that axons from the remaining eye are capable of producing their normal complement of LGN layers. The development of the LGN ON-center layers, 1 and 2, and the interlaminar space between them are more affected by TTX treatment than are the other layers. By contrast, APB eye injections do not selectively affect the development of the ON-center layers, but do result in some slowing of overall LGN development. Taken together, these results suggest that activity of retinal afferents is not essential for initiating interlaminar space formation, but is important for the normal pace of maturation of LGN cell layers.

Action Potentials↗
PubMed1988

The arrangement of the muscle layers at the equine ileocaecal junction.

The muscle layers of the ileocaecal junctions of horses (n = 18), plains zebras (Equus burchelli antiquorum) (n = 3), mountain zebras (Equus zebra zebra) (n = 2), and a donkey were examined macroscopically and microscopically. The muscular tunic of the ileocaecal papilla was made up of 3 layers: an innermost circular layer which was a continuation of the circular muscle of the ileum, a central longitudinal layer which was a continuation of one part of the longitudinal layer of the ileum and an outermost layer, composed of two collateral semicircular lips, formed by the circular layer of the caecum. The other part of the longitudinal ileal muscle layer contributed to the dorsal caecal taenia. The circular and semicircular muscle layers contributed by the ileum and caecum respectively represented what could be termed as a M. sphincter ilei, which did not exist as a separate annular muscle confined only to the papilla as the name would suggest. The amount of intermuscular connective tissue increased in both these layers towards the tip of the papilla, while at the same time the layers decreased in thickness. This finding supports the view that their sphincteroid action would be less efficient and that an additional closing mechanism of vascular origin may be required at the ileocaecal papilla of the horse.

Animals↗
PubMed1985

Separation of human blast progenitors from granulocytic, erythroid, megakaryocytic, and mixed colony-forming cells by "panning" on cultured marrow-derived stromal layers.

Primitive myeloid progenitor cells will adhere to stromal feeder layers of human bone-marrow-derived adherent cells grown in the presence of methylprednisolone (MP+ layers). These progenitors form colonies of blast cells on the MP+ stromal layers, but not on stromal layers grown in the absence of MP (MP- layers). The present study was designed to determine whether this failure of colony formation was caused by inability of the progenitors to adhere to the MP- layers or inability to proliferate in their presence. We also compared the capacities of the blast progenitors to adhere to MP+ and MP- stromal cells with those of mixed (GEMM-CFC), erythroid (BFU-E), megakaryocytic (Mk-CFC), and granulocyte-macrophage (GM-CFC) colony-forming cells. Incubation of bone marrow mononuclear cells with MP+ stromal layers removed 90% of the blast progenitors, but did not remove the majority of the GEMM-CFC, BFU-E, Mk-CFC, and GM-CFC; incubation of bone marrow mononuclear cells with MP- stromal layers did not remove the blast progenitors or the GEMM-CFC, BFU-E, Mk-CFC, and GM-CFC. Thus, the blast progenitors adhere to MP+ stromal feeder layers, but not to MP- stromal layers. In this respect they differ from the other more mature colony-forming cells that do not show any marked tendency to adhere to either type of stromal layer.

Bone Marrow Cells↗
PubMed1993

[The layers of the gallbladder wall: an ultrasound-anatomic comparative study].

In a sonographic-histological comparative test, operatively withdrawn gallbladders in native and formol-fixed states were examined. The thickness of the gallbladder wall and of its layers was measured sonographically. Afterwards the gallbladders were reexamined microscopically in the sonographic sectional plane and the measurement was repeated. By removal of the single layers of the wall and by repeated sonographic measuring, sonographic and microscopic measurements of the parietal layers could be correlated. Both gallbladder wall thickness and thickness of the single anatomic layers can be evaluated sonographically. The correlation between sonographic and histological measurements is fairly to highly significant. The sonographically measurable layers can be related to the following anatomical layers (when measuring from outwards to inwards): 1. echogenic layer = initial echo and subserosa; 2. echo-poor layer = muscularis; 3. echogenic layer = lamina propria; 4. echo-poor layer = mucosal epithelium; 5. echogenic layer = exit echo.

Cholecystectomy↗
PubMed1993

Organized growth of thalamocortical axons from the deep tier of terminations into layer IV of developing mouse barrel cortex.

The thalamocortical projection to rodent somatosensory ("barrell") cortex is highly ordered in both the radial and the tangential dimensions. During a brief period of postnatal development, thalamocortical axons establish two tiers of terminations, in the deep layers and in layer IV, and form whisker-specific clusters within layer IV; however, little is known about the cues that guide them to their appropriate radial and tangential positions. To gain insight into potential mechanisms underlying this process, we studied the development of thalamocortical termination patterns in mouse barrel cortex at high spatial resolution. Developing thalamocortical axons were labeled in fixed slices with the lipophilic carbocyanine dye Dil and imaged with a laser scanning confocal microscope. On the day of birth (postnatal day 0, P0) axons coursed through layers VI and V, with little or no branching. By P2 the lower tier of terminations, at the border of layers VI and V, was clearly identifiable. Below this tier axons coursed obliquely or tangentially, forming a dense meshwork of intersecting fibers, but with no apparent branching. By P4 the upper tier of terminations, in layer IV, was clearly recognizable, and consisted of periodic, dense clusters of terminal arborizations. In marked contrast to the oblique and apparently disorderly course followed by axons in layer VI and lower layer V, axons in upper layer V heading toward the upper tier were organized in loose bundles running radially, suggesting that axons destined to terminate in a particular layer IV barrel had already reached their appropriate tangential coordinates within the lower tier. Thus, the pattern of thalamocortical terminations in layer IV seems to be projected from the deep tier of terminations, and does not develop from an initially profuse arborization pattern through pruning of inappropriate branches.

Animals↗
PubMed1995

A histocytological study of the rat hair follicle--an appraisal of a monocellular layer ("middle root sheath") between inner and outer root sheaths.

Hair follicles of male Wistar rats in the anagen stage were examined by light and electron microscopy. A distinct monocellular layer was identified between the Henle's layer and the outer root sheath (ORS). In the lower part of the ORS, this cell layer is more closely bound to the inner root sheath (IRS) than to the ORS, while in the upper half the situation is reversed. Electron density and staining property of this layer are gradually changed according to regions of the hair follicle which may indicate the metabolic conditions of the organism. The origin of this layer can be traced back to the germinal matrix directly facing the neck of the hair papilla. Findings are also reported about the gaps formed between the cells of Henle's layer after keratinization and about the contact formed between the cells of Huxley's layer and the cells of this monocellular layer through these gaps. Our observation reported in this study strongly suggests that this layer belongs neither to the IRS nor to the ORS, but that it represents an independent layer of cells. Therefore we propose to name this layer the "middle root sheath." This middle root sheath may serve the following three functions: 1) alleviation of intrinsic friction generated by colliding cell dynamics between the IRS and the ORS, 2) deterrence of keratinization of the ORS after exfoliation of the IRS and 3) secretion and excretion of metabolites.

Animals↗
PubMed1997

Effects of lifelong ethanol consumption on cerebellar layer volumes in AA and ANA rats.

Aging and chronic alcohol consumption can cause degenerative changes in the cerebellar cortex. In this study, the effects of aging and lifelong alcohol consumption on cerebellar cortical layer volumes (molecular and granular) and also white matter layer volumes were studied in alcohol-preferring (AA) and nonpreferring (ANA) rats of both sexes. The ethanol-consuming animals (EtOH) had 12% (w/v) ethanol as the only available fluid from 4 to 22 months of age, whereas the young (3 month) and old controls (24 months) had only water to drink. The volumes of molecular, granular, and white matter layers of the cerebellar vermis in folia II, IV, VII, and X were measured by using systematic sampling and a point-counting method. The volumes of the granular and white matter layers showed consistent increase between 3 and 24 months of age, whereas the volume of the molecular layer remained unchanged with increasing age. Individual ethanol intake was measured over a 1-week period at the beginning and at the end of chronic ethanol exposure. Significant (ANOVA, p = 0.000) sex difference was found in the drinking behavior in both lines, with females consuming more alcohol than males (daily ethanol consumption at 22 months of age 3.2 +/- 0.3 vs. 7.1 +/- 0.3 g/kg for AA males and females; 3.2 +/- 0.3 vs. 5.4 +/- 0.4 g/kg for ANA males and females, respectively). The only ethanol-induced effect on the cerebellum was observed in ANA-EtOH females with a 15% reduction in the volumes of the molecular and granular layer in folium II compared with age-matched controls and a significant (p < 0.05, analysis of covariance with ethanol intake as a covariate) line difference in folium II (molecular and granular layers) was observed between ANA-EtOH females and AA-EtOH females. Furthermore, the volume of the molecular layer in folium II was significantly (p < 0.05, analysis of covariance with ethanol intake and body weights as covariates) reduced for ANA-EtOH females, compared with ANA-EtOH males indicating a sex difference in the cerebellar degeneration due to chronic alcohol consumption. Of the three layers studied, the white matter layer was the most resistant layer to the effects caused by chronic alcohol consumption. In view of the fact that AA and ANA rats of both sexes differ regarding the drinking behavior and ethanol metabolism, they provide an important model for further research on ethanol-induced pathological changes in the central nervous system.

Acetaldehyde↗
PubMedDate not supplied

Comparison of single- and two-layer Percoll separation for selection of motile spermatozoa.

OBJECTIVE: Sperm recovery using a single-layer Percoll procedure is significantly better than using the swim-up technique for infertile men and patients with normal sperm characteristics; however, in normal men results have been contradictory. Some studies have shown further improvement in semen quality with multiple layers. Therefore, this study compared the effect of single-layer and two-layer Percoll procedures on sperm characteristics of normozoospermic men. METHODS: Semen specimens from 10 normal donors were processed by layering 1 mL of the liquefied ejaculate on a single layer of 80% Percoll or on a two-layer (47% and 90%) Percoll gradient. Computer-assisted semen analysis was done to examine total motile sperm, percentage of recovery of motile cells, percent motility, curvilinear velocity, linearity, and amplitude of lateral head displacement. Each specimen was evaluated by the hypo-osmotic swelling (HOS) test, bovine cervical mucus penetration test, viability (eosin-nigrosin stain), and sperm morphology (World Health Organization and Kruger's strict criteria). RESULTS: Specimens processed with the two-layer Percoll procedure had significantly better recovery of spermatozoa, and significantly better percentage motility, linearity, amplitude of lateral head displacement, percentage tail swelling, and percentage viability than those separated on single-layer Percoll. Results for sperm morphology using WHO and Kruger's criteria were similar between the two methods (P = 0.92 for both sets of criteria). CONCLUSIONS: In normozoospermic men, the two-layer Percoll separation procedure significantly improves semen characteristics compared with separation on a single layer.

Animals↗
PubMed1999

Fate of human retinal pigment epithelial cells seeded onto layers of human Bruch's membrane.

PURPOSE: To determine the fate of human retinal pigment epithelial (RPE) cells seeded onto different layers of human Bruch's membrane (BM). METHODS: Bruch's membrane explants were prepared from 16 human cadaver eyes (7 eyes age <50 years; 9 eyes >50 years) by removing native RPE cells with ammonium hydroxide to expose the RPE cell basal lamina (BL). The inner collagenous layer (ICL) and elastin layer (EL) were exposed by removing apical layers sequentially by mechanical and enzymatic means. Synchronized first passage human RPE cells (15,000 cells/(6-mm-diameter explant) were plated onto each layer of human BM. The RPE cell reattachment and apoptosis rates at 24 hours, proliferation rates and mitotic index 24 hours after growth stimulation, and the ability of RPE cells to repopulate the explant surface were determined on each layer. RESULTS: RPE cell reattachment was highest on BL but decreased on deeper layers of BM. The apoptosis rate of attached cells increased as deeper layers of BM were exposed. The proliferation rate and mitotic index of the grafted cells were higher on BL than on deeper layers. RPE cells plated onto BL repopulated the explant surface within 14 +/- 3 days, whereas cells plated onto the ICL and EL eventually died and never reached confluence. CONCLUSIONS: The fate of RPE cells seeded onto BM depends on the ultrastructural layer of BM available for reattachment. These findings suggest that the ability of transplanted RPE cells to repopulate bare BM will depend on the layer of BM available for RPE cell reattachment.

Adolescent↗
PubMed1996

Morphological properties of intracellularly labeled layer I neurons in rat neocortex.

The morphology of neurons in layer I of rat neocortex, including Cajal-Retzius (CR) cells, was studied by using intracellular biocytin staining in brain slices obtained from rats during the first 22 postnatal days. Within the first postnatal week, horizontal bipolar neurons or CR cells were prominent in layer I. Typically, CR cells had one main dendrite and one axon originating from opposite poles of the somata. Even though the main dendrites and axons could be quite long, complex dendritic or axonal arbors were not observed. Starting around postnatal day 6 (PN 6), CR cells were less frequently observed. From PN 10 to PN 21, nonpyramidal neurons with diverse morphologies became the main neuronal component in layer I. The somata of layer I nonpyramidal neurons were quite variable in size and shape. Dendrites were smooth or sparsely spiny, and the dendritic trees were mainly restricted to layer I, covering an area with a diameter of about 200 microns. Axon collaterals of these cells formed elaborate arbors with diameters of around 700 microns in layer I and extending, in many cases, to layer II/III and even layer IV. This extensive axonal plexus provides a rich anatomical base on which layer I neurons, functioning as local circuit elements, may interact with each other and with neurons in other layers.

Animals↗
PubMed2000

Thin-layer technology: tempered enthusiasm.

With the introduction of new technologies we often see a pattern of development. As a useful technology moves into the public sector there is often an episode of wild enthusiasm and uncritical acceptance, followed by a time of progressive disillusionment. However, with time and experience, a proper place for the method becomes established. Thin-layer technology is certainly an improvement and solves many of our preanalytical problems; however, it introduces some difficulties of its own. The rounding up of cells in liquid fixation makes cells of high-grade lesions smaller than they would be on a conventional preparation. The abnormal cells are often separated. For both of these reasons they may be overlooked. Furthermore, benign glandular cells can take on an ominous appearance. These differences in conventional and thin-layer morphology are proving to be a fruitful area for publication. Thin-layer technology cannot be all things to all situations, and this is especially true in body fluid and fine-needle cytomorphology. In our experience, while occasionally helpful, the thin-layer technique should not be the primary method for diagnosis in nongynecologic specimens. Time and effort would be better spent on trying to educate select clinicians on how to obtain better samples than to totally convert to thin-layer methodologies. Regarding FNA, the patient is best served when the pathologist is directly involved with the initial sample acquisition. Reimbursement is available for immediate sample interpretation, so funding should be available for staffing if an institution has the interest. For the record, we believe that liquid fixation and thin-layer methodology should not be the primary method for FNA, unless circumstances are absolutely prohibitive. An important problem with thin-layer technology lies with its added cost. Thin-layer interposes another series of steps into cytologic sample preparation. There is additional labor, additional time, another machine in the laboratory, and the significant cost of the reagents. In a situation where the price of a cytologic test is already close to margin, costs of the vial, filter, and preservative throw the test into unprofitability. Price structures have to be changed. Some institutions are waiting until there is more competition in the market and costs decrease. Alternatively, a lot of effort has been expended in trying to get government and other groups to accept the additional costs of the new test for gynecologic examinations, and many payers seem to be falling in line to accept the methodology, secondary to clinician and patient demand. Basic questions about ancillary technologies and gynecologic samples remain to be answered. Cytology is big business. Every year a significant segment of the population has a Pap smear performed. Hardly any other laboratory test can claim the volume of activity of the cervical smear. Any business that can hook into that market stands to prosper. Since the Pap smear has some well-publicized problems, the door is open for technology to nibble away at a few percentage points of false negativity. We are far from the first to ask if we can afford the incremental improvements of thin-layer and other ancillary technologies. There is a conundrum. Government, insurance companies, and our administrators are calling for us to hold back cost increases in medical care. Alternatively, these new technologies, patient demand for the perfect test, increased regulatory oversight, and legal challenges are increasing the cost of doing business. We do not know how to respond to the often-voiced fear that these ancillary technologies increase the cost of cytology services beyond some patients' ability to pay. In this confusion, we do know that we should use the best test to get the most accurate answer for our patients. In selected scenarios this may mean that we will have to accept the cost and follow thin-layer technology.

Breast Neoplasms↗
PubMed2005

Morphological and electrophysiological properties of lateral entorhinal cortex layers II and III principal neurons.

The intrinsic electrophysiology and morphology of neurons from layers II and III of the lateral entorhinal cortex (EC) was investigated in a rat brain slice preparation by intracellular recording and biocytin labeling. Morphologically, we distinguished three groups of layer II principal neurons. The most numerous group included cells with multiple radiating dendrites that spread over layers II and I in a fan-like fashion. While morphologically "fan" neurons were similar to the "stellate" cells of the medial EC, electrophysiologically the fan cells lacked the persistent rhythmic subthreshold oscillations and the very pronounced time-dependent inward rectification typical of the stellate cells. The second group consisted of pyramidal cells that manifested regular spike firing and had a more negative resting potential and a longer spike duration than the fan cells. In the third group we included all those neurons that had diverse multipolar appearances distinct from the fan cells. Neurons in this group had electrophysiological profiles intermediate between those of the fan and pyramidal cells. All neurons recorded in layer III were pyramidal in shape with a basal dendritic tree that could extend into layer V and an axon that could also give off collaterals into layer V. Electrophysiologically, layer III pyramidal cells were very similar to those of layer II. On the basis of these and other data we suggest that in different EC regions layer II neurons may be conducting more input-dependent specialized processing, while cells from layer III may perform a more global or generalized function.

Animals↗