Laminar Volume Research Articles

Temporo-Parietal Flap Incorporated Into a Modified Osteo-Odonto Keratoprostheses Protocol for Longevity of the Dental Lamina.

To describe a novel pedicled temporo-parietal flap to delay laminar resorption in a modified osteo-odonto keratoprosthesis (MOOKP) and measure resorption of the dental lamina by an objective method. A retrospective case series was performed on patients who received an osteo-odontokeratoprosthesis for Steven-Johnson-Syndrome. Surgeries were performed between October 2016 and November 2017 by the same surgical team (G.M. and S.W.). A modified temporo-parietal flap was incorporated into stage 1 of the MOOKP procedure. CT Scans were performed post op and on follow up. Volumetric evaluation was achieved by automated software analysis of 3D reconstructed CT images (Vitrea, Software Version 6.7.6, Cannon Medical Systems ANZ Pty Ltd). The procedure was performed in 3 eyes from 3 patients. Patients were followed up for stage 2 review at 9.6 months on average (22-55 weeks). One case was complicated by early postoperative hematoma of the buccal graft; however, this was managed conservatively. Another case required relaxing incisions at the time of flap creation due to increased vascularized collagenous tissue. On follow up, volume changes in the dental lamina were minimal. Loss of laminar volume can potentially jeopardize the success of the MOOKP, and consequently cause significant visual, graft or globe complications. The long-term success of this method needs further evaluation; however, initial results suggest a possible role for pedicle grafts in maintenance of the dental lamina. Furthermore, objective CT-based calculation of laminar volume may reduce inter-study variability and standardize comparison of techniques.

Sublimation as a function of diffusion

Purification of large organic molecules in a tubular sublimator occurs by a combination of laminar flow, Knudsen diffusion, and volume diffusion. For laminar flow, the amount purified per area per driving force varies with pd2, where p is pressure and d is tube diameter. For Knudsen diffusion, it varies with d and is not a function of pressure. For volume diffusion, it is constant, consistent with experiment. This volume diffusion mechanism may offer an alternative explanation to slip flow for dilute gas transport of both organic semiconductors and common low molecular weight gases. © 2015 American Institute of Chemical Engineers AIChE J, 62: 861–867, 2016

Serial 3-Dimensional Computed Tomography and a Novel Method of Volumetric Analysis for the Evaluation of the Osteo-Odonto-Keratoprosthesis

To assess the use of serial computed tomography (CT) in the detection of osteo-odonto-lamina resorption in osteo-odonto-keratoprosthesis (OOKP) and to investigate the use of new volumetric software, Advanced Lung Analysis software (3D-ALA; GE Healthcare), for detecting changes in OOKP laminar volume. A retrospective assessment of the radiological databases and hospital records was performed for 22 OOKP patients treated at the National OOKP referral center in Brighton, United Kingdom. Three-dimensional surface reconstructions of the OOKP laminae were performed using stored CT data. For the 2-dimensional linear analysis, the linear dimensions of the reconstructed laminae were measured, compared with original measurements taken at the time of surgery, and then assigned a CT grade based on a predetermined resorption grading scale. The volumetric analysis involved calculating the laminar volumes using 3D-ALA. The effectiveness of 2-dimensional linear analysis, volumetric analysis, and clinical examination in detecting laminar resorption was compared. The mean change in laminar volume between the first and second scans was -6.67% (range, +10.13% to -24.86%). CT grades assigned to patients based on laminar dimension measurements remained the same, despite significant changes in laminar volumes. Clinical examination failed to identify 60% of patients who were found to have resorption on volumetric analysis. Currently, the detection of laminar resorption relies on clinical examination and the measurement of laminar dimensions on the 2- and 3-dimensional radiological images. Laminar volume measurement is a useful new addition to the armamentarium. It provides an objective tool that allows for a precise and reproducible assessment of laminar resorption.

Altered volume and hemispheric asymmetry of the superficial cortical layers in the schizophrenia planum temporale

In vivo structural MRI studies in schizophrenia auditory cerebral cortex have reported smaller volumes and, less consistently, have reported altered hemispheric asymmetry of volumes. We used autopsy brains from 19 schizophrenia and 18 nonpsychiatric male subjects to measure the volume asymmetry of the planum temporal (PT). We then used the most recently autopsied 11 schizophrenia and 10 nonpsychiatric brains to measure the widths and fractional volumes of the upper (I-III) and lower (IV-VI) layers. Measurements of whole PT gray matter volumes did not show significant changes in schizophrenia. Nevertheless, laminar volume measurements revealed that the upper layers of the PT comprise a smaller fraction of the total cortex in schizophrenia than in nonpsychiatric brains. Subdivision of the PT showed that this change was especially prominent caudally, beyond Heschl's gyrus, whereas similar but less pronounced changes were found in the rostral PT and Heschl's gyrus. Complementary measures of laminar widths showed that the altered fractional volume in the caudal left PT was due mainly to approximately 8% thinner upper layers. However, the caudal right PT had a different profile, with thicker lower layers and comparatively unchanged upper layers. Thus, in the present study, laminar measurements provided a more sensitive method for detecting changes than measurement of whole PT volumes. Besides findings in schizophrenia, our cortical width measurements revealed normal hemispheric asymmetries consistent with previous reports. In schizophrenia, the thinner upper layers of the caudal PT suggest disrupted corticocortical processing, possibly affecting the multisensory integration and phonetic processing of this region.

Auditory cortex in schizophrenia: An unbiased stereologic method for determination of regional and laminar volume changes

Auditory cortex in schizophrenia: An unbiased stereologic method for determination of regional and laminar volume changes

Three dimensional colour Doppler echocardiography for the characterisation and quantification of cardiac flow events

The accurate non-invasive quantification of cardiac flow volumes is an important goal in clinical cardiology. Computation of laminar volume flow through the ventricular outflow tracts would allow direct measurement of...

Olfactory bulb development is altered in small‐eye (Sey) mice

Small-eye (Sey) is a spontaneous, semidominant murine mutation that results from a point mutation in the Pax-6 gene. Both the eyesthe olfactory system fail to develop in homozygotesthese animals die neonatally. Heterozygotes (Sey/+) have different degrees of eye abnormalities including decreased lens sizecataracts. In the present study, we examined whether one mutated allele of Pax-6 also affects olfactory system development. By 42 days of age, main olfactory bulb volume was significantly decreased in Sey/+ animals compared with wild-type littermates,this effect was even more dramatic in 70-day-old animals. In contrast, there was no effect on accessory olfactory bulb, olfactory epithelial, or vomeronasal organ development at any age in Sey/+ animals, demonstrating the specificity of the effect. In the main olfactory bulb, the largest differences in laminar volume were found in the glomerulargranule cell layers. These layers contain the olfactory bulb interneurons,a subpopulation of these cells were found to be Pax-6 immunoreactive. Examination of the neurochemical consequences of this mutation showed that the number of both tyrosine hydroxylase (TH)-gamma-aminobutyric acid (GABA)-immunoreactive profiles were dramatically decreased in Sey/+ animals as compared with controls. In contrast, neither calretinin nor calbindin immunoreactivity was affected by this mutation. Dual-labeling immunohistochemistry showed that nearly all TH-immunoreactive cellsa subpopulation of GABA-immunoreactive cells coexpressed Pax-6. However, calretinin-calbindin- immunoreactive cells were not Pax-6 immunopositive. These data indicate that two normal alleles of Pax-6 are required for normal olfactory bulb development and, as part of this effect, this gene may be involved in the development of specific neurotransmitter systems. J. Comp. Neurol. 402:402–418, 1998. © 1998 Wiley-Liss, Inc.

Olfactory bulb development is altered in small-eye (Sey) mice

Small-eye (Sey) is a spontaneous, semidominant murine mutation that results from a point mutation in the Pax-6 gene. Both the eyes and the olfactory system fail to develop in homozygotes and these animals die neonatally. Heterozygotes (Sey/+) have different degrees of eye abnormalities including decreased lens size and cataracts. In the present study, we examined whether one mutated allele of Pax-6 also affects olfactory system development. By 42 days of age, main olfactory bulb volume was significantly decreased in Sey/+ animals compared with wild-type littermates, and this effect was even more dramatic in 70-day-old animals. In contrast, there was no effect on accessory olfactory bulb, olfactory epithelial, or vomeronasal organ development at any age in Sey/+ animals, demonstrating the specificity of the effect. In the main olfactory bulb, the largest differences in laminar volume were found in the glomerular and granule cell layers. These layers contain the olfactory bulb interneurons, and a subpopulation of these cells were found to be Pax-6 immunoreactive. Examination of the neurochemical consequences of this mutation showed that the number of both tyrosine hydroxylase (TH)- and gamma-aminobutyric acid (GABA)-immunoreactive profiles were dramatically decreased in Sey/+ animals as compared with controls. In contrast, neither calretinin nor calbindin immunoreactivity was affected by this mutation. Dual-labeling immunohistochemistry showed that nearly all TH-immunoreactive cells and a subpopulation of GABA-immunoreactive cells coexpressed Pax-6. However, calretinin- and calbindin-immunoreactive cells were not Pax-6 immunopositive. These data indicate that two normal alleles of Pax-6 are required for normal olfactory bulb development and, as part of this effect, this gene may be involved in the development of specific neurotransmitter systems.

Effects of unilateral olfactory deprivation in the developing opossum, Monodelphis domestica.

Unilateral naris closure in young rodents leads to striking alterations in the development of the ipsilateral olfactory system. One of the most pronounced effects is a 25% reduction in the size of the experimental olfactory bulb, a change that stems in part from decreased cell survival. Since naris occlusion in rodents alters the system more during development than in adulthood, we investigated the consequences of olfactory deprivation in a species that is born in a very immature state, Monodelphis domestica. In this pouchless marsupial, offspring are born after a short 14-day gestation. In the present study, the thymidine analogue bromodeoxyuridine was used to examine early postnatal neurogenesis in the olfactory bulb. Unlike rats and mice, neurogenesis of the main output neurons (the mitral cells) continues into postnatal life. Unilateral naris closure was begun on postnatal day 4 (P4) or P5 in Monodelphis and continued for 30 or 60 days. Laminar volume measurements revealed a significant reduction in the size of the experimental bulb following 60, but not 30, days of early olfactory deprivation. Mitral cell number estimates indicated a significant reduction after both 30 and 60 days of naris closure. The immaturity of Monodelphis offspring may render the population of mitral cells susceptible to the effects of olfactory deprivation. These findings suggest that afferent activity plays a role in the survival of all bulb neurons, irrespective of cell class.

Unilateral naris closure and vascular development in the rat olfactory bulb

The blood supply to the brain has been linked closely to nervous system function and metabolism, thereby possibly playing a direct role in brain maturation. Previously, we demonstrated that closure of an external naris early in life results in large changes within the olfactory bulb, including reductions in laminar volume and cell number and a rapid decline in metabolism and protein synthesis. To understand the role of the blood supply in the dramatic changes following naris closure, the present study examines the development of olfactory bulb vasculature in unilaterally odor-deprived and control rats. On post-partum day 1 (P1; the day after birth), littermate rat pups underwent either unilateral naris occlusion or sham surgery. On P5, P10, P15, P20, P30 and P60, animals were perfused with an india ink-gelatin mixture to assess blood vessel amount and complexity. Densitometric analyses were performed to obtain values of blood vessel area ratios (vessel area/tissue area), branch point number and branch point density. Considerable vessel development in all bulbs occurred over the first two to three weeks post-partum. By P20, large reductions in vessel area ratios were observed in all constituent laminae of deprived bulbs. While similar reductions in number of vessel branch points/tissue area were seen, few changes were noted in the number of branch points/vessel area. The effects were primarily confined to early developmental periods: bulb vasculature in animals deprived at older ages (P40) appeared normal. The results indicate that the vasculature responds to alterations in sensory stimulation early in life, therefore potentially playing an important regulative role in neural development.

Rapid changes in 2-deoxyglucose uptake and amino acid incorporation following unilateral odor deprivation: a laminar analysis

Unilateral naris occlusion in neonatal rats results in large alterations in the olfactory bulb, including substantial changes in laminar volume and enhanced cell death. These gross changes are undoubtedly the result of a cascade of more basic cellular regulatory events. The present study assesses the possibility of rapid post-deprivation changes in two such processes: glucose metabolism and protein synthesis. On the day after the day of birth rat pups underwent unilateral naris occlusion or sham surgery. In one study, either 1, 12, 24 or 48 h following surgery [ 3H]2-deoxyglucose ([ 3H]2-DG) was administered to gauge patterns of glucose uptake. In a second study, [ 3H]leucine was injected to assess patterns of protein synthesis. Autoradiographs were then subjected to quantitative analyses. As early as 1 h following occlusion reduced 2-DG uptake was observed in many bulb regions. By 24 h, leucine incorporation was also uniformly diminished. While 2-DG uptake remained suppressed 48 h after deprivation, levels of amino acid incorporation returned to normal patterns in most laminae, with the exception of the mitral cell layer, where increased uptake was encountered. To evaluate whether the effects were developmental by nature a group of P40–P45 animals treated similarly were also examined. While 24 h of deprivation impaired 2-DG uptake in older animals, no alterations in amino acid incorporation were observed. The results indicate that early odor deprivation has rapid and specific effects on cellular functioning within the developing olfactory bulb.

Distribution of neurons and glia in the visual cortex (area 17) of the adult albino rat: A quantitative description

The neuronal and glial cell composition of the rat visual cortex (area 17) has been determined quantitatively using stereological techniques. The volume numerical densities (number of cells per mm 3 of cortex) of neurons and of the principal glial cell types (astroglia, oligodendroglia, and microglia) were calculated from tangential semithin resin sections spaced at regular intervals 50 μm apart throughout the entire depth of the visual cortex. From measurements of cortical and laminar thickness the separate volume numerical densities of neurons and glial cells were derived for each lamina in the cortex. In addition, the absolute numbers of cells in each lamina under 1 mm 2 of cortical surface were calculated. The mean cortical volume numerical density of neurons was60,020 ± 3840/mm 3 (X ¯± SEM; n = 8), and49,040 ± 2610/mm 3 for the combined glial cell types. Astroglia, oligodendroglia, and microglia were present in a ratio of 6:3:1 respectively. It was determined from neuronal and glial somatic volume estimates that the somata of these cells occupied approximately 13.5% of unit cortical volume, with 81.3% of the unit volume being occupied by cortical neuropil. Using previously published reports that described the laminar composition of neurons in terms of the relative proportions of pyramidal and non-pyramidal cells, the laminar volume numerical densities for these neuronal categories have been derived. In addition, it has been estimated that under 1 mm 2 of cortical surface there are 79,500 pyramidal and 7790 non-pyramidal neurons distributed throughout layers 1–6 of the rat visual cortex.

Unilateral odor deprivation: Time course of changes in laminar volume

Unilateral olfactory deprivation on Day 1 results in large reductions in olfactory bulb size when animals are examined in the juvenile period. The present study explored 2 issues. First, the development of changes in laminar volume was measured in order to determine when differences in olfactory bulb size emerge. Rat pups underwent surgical closure of one naris on Day 1 and laminar sizes were examined on either day 4, 8, or 12. Reliable differences emerged between “deprived” and control bulbs by Day 12. Second, to determine the length of the period of susceptibility to changes in sensory input, pups were deprived on either Day 10 or 20 and reared for thirty days. Deprivation at both ages reduced bulb size, although treatment at the later age resulted in less severe alterations.

Hippocampal maturation in the precocial murid rodent Acomys cahirinus.

Growth rates in the dentate gyrus and hippocampus proper of the precocial murid Acomys cahirinus were examined by measuring age-related changes in laminar volume in 0-, 10-, 20-, and 60-day postpartum animals. A biphasic course of maturation was observed in both structures, with rapid expansion occurring in the first 10 postnatal days and more gradual growth thereafter. This pattern of growth resembles those reported for newborn altricial murids such as the laboratory mouse and rat. However, due to the large differences in the length of gestation between Acomys and the rat and mouse, quite different patterns emerge when the species are compared on the basis of postconception age, indicating that rates of neural maturation are not the same in altricial and precocial murids .

Unilateral odor deprivation: Differential effects due to time of treatment

Rats were unilaterally deprived of odor stimulation by surgically sealing one naris 1, 30 or 60 days after birth. Thirty days later the laminar volumes of the olfactory bulb ipsilateral to the occluded naris were compared with those ipsilateral to the normal side. Deprivation from days 1–30 resulted in approximately 25% reductions in “deprived” bulb size, corroborating results reported by others. Altered experience at older ages had little effect on laminar volume suggesting that deprivation does not produce atrophy per se, but interacts with early developmental processes to result in differential bulb size.

Olfactory bulb maturation in Acomys cahirinus: is neural growth similar in precocial and altricial murids?

Olfactory bulb maturation was assessed in the precocial murid Acomys cahirinus by quantifying developmental changes in laminar volume and glomerular and mitral cell size. At the time of birth (38 days postconception), the Acomys bulb is in a developmental state similar to that of altricial murids of the same gestational age. Rapid growth occurs in Acomys during the first 10 postnatal days with more gradual changes occurring thereafter. Altricial murids also exhibit accelerated bulb development in early postnatal period, but growth rates have declined by 38 days after conception. These results suggest that maturation is not similar in precocial and altricial murids and that rapid postnatal development is a necessary feature of murid brain development.