Cut Slices Research Articles

Growth kinetics of fibroblasts on bovine dentin

In vitro dentin barrier tests published so far show several shortcomings. Therefore, we designed a new test method using bovine dentin disks on which cells were grown on one side. In this study, we evaluated the growth kinetics of L-929 mouse fibroblasts on dentin disks of 0.75-mm thickness and 4-mm diameter derived from lower incisors of freshly slaughtered bovines. The application of 50% citric acid for 30 s was optimal for the gentle removal of the smear layer from the cut dentin slices. Growth kinetics of mouse fibroblasts depended on the initially plated cell density: optimal cell growth on the disks was observed with approximately 200 cells/mm2, which was the same as the growth rate on the bottom of a cell culture vessel. Consequently, bovine dentin disks are a suitable substrate for normal cell growth, and this set-up can be used in a dentin barrier test.

Implementation of DEDXS A differential energy-dispersive X-ray spectroscopy system

A differential energy-dispersive X-ray spectroscopy system has been assembled. It consists of a conventional Si(Li) or Ge solid-state detection unit whose output is routed to four 2048-channel segments of an EG&G ADCAM 100 MCA data acquisition system by logic signals from a control unit that operates at either 1 or 10 Hz. Operational details are given. The use of the system for electric-field modulation studies is also described and is illustrated by results from some 128°-rotated y- x cut slices of LiNbO 3. These have been observed in fields up to 9 kV/mm in reflection and up to 2.8 kV/mm in transmission using synchrotron radiation. Some limitations of the present system are noted and some desirable modifications indicated.

Power Requirement of a Rotary Tiller in Saturated Soil

A mathematical model for predicting the power requirement of a rotary tiller in saturated soil has been developed. The model assumes that power required by a rotary tiller is used for cutting the soil, throwing the cut soil slices by centrifugal action of the tines, overcoming soil-metal friction, soil-soil sliding friction, and overcoming parasitic forces.

Sodium Lignin Sulfonate and Sodium Orthophenylphenate Interaction on Browning of Pear Fruits

Immersion of Anjou pears (Pyrus communis L. cv. Beurre d Anjou) in sodium lignin sulfonate (SLS), a flotation agent used in hydraulic handling of pears, did not cause injury leading to skin browning. Immersion of cut pear slices in SLS discolors pear fruit flesh, but the discoloration derived from SLS pigments does not intensify with time. When the fungicide sodium orthophenylphenate (SOPP) was combined with SLS, necrotic skin mottling occurred with increased immersion times and temperatures. A white precipitate in the SLS SOPP solution accompanied phytotoxicity of pear skin tissue. Acidification of alkaline SOPP solutions (pH 11.3) with 0.01 N HCl down to pH 10 produced mild skin necrosis. Both acid (0.01 N HC1) and alkaline (0.01 n KOH) solutions of SOPP and SLS-SOPP combinations caused browning of pear flesh.

Mechanisms of cell killing in photodynamic therapy using a novel in vivo drug/in vitro light culture system.

Photodynamic therapy of certain neoplasms has emerged as a promising form of cancer treatment. This type of therapy involves the exogenous administration of a photosensitizer with subsequent exposure to light. The ensuing photochemical reaction results in destruction of the tumor. Whether tumor cells are destroyed directly by the photodynamic treatment or indirectly as a result of destruction of the tumor microvascular bed is unknown. To address this question, methods were adapted to test whether combinations of a photosensitizer and light resulted in direct cell killing of precision cut tissue slices placed in culture. The major advantages of this culture system are that photosensitizers are administered in vivo, tissue slices produced in minutes, placed in culture medium, and irradiated in vitro. Any resulting cellular destruction occurs in the absence of a functioning vascular system and indicates that photodynamic therapy acts through a direct cell killing mechanism. Tissue slice viability was monitored by two standard methods: assay for intracellular potassium and morphological examination at the electron microscopic level. The effects of hematoporphyrin derivative and light were examined on tissue slices produced from a prostate adenocarcinoma transplanted into male Copenhagen rats. The data indicate that direct killing of tumor slices occurs and is dependent on the irradiation protocol used.

The Effect of Medetomidine on GABA and Benzodiazepine Receptors in Vivo: Lack of Anxiolytic but some Evidence of Possible Stress‐Protective Activity

Medetomidine, a new selective alpha 2-adrenoceptor agonist, potentiated bicuculline seizures in mice. In vivo pretreatment with medetomidine in mouse cerebral cortex reduced dose-dependently (2.5-100 micrograms/kg) GABA-potentiated 3H-flunitrazepam binding. The affinity of 3H-muscimol was also reduced by medetomidine. This effect of medetomidine on GABA-potentiated benzodiazepine binding was reversed by pretreatment with atipamezole (1 mg/kg), a specific alpha 2-antagonist. In an elevated plus-maze model of anxiety medetomidine (0.5-10 micrograms/kg) was inactive both in rats and mice and did not antagonize the behavioural effects of an anxiogenic beta-carboline, DMCM. However, at lower doses medetomidine (10 but not 50 micrograms/kg) antagonized the swimming stress caused increase of central benzodiazepine binding sites (labeled with 3H-Ro 15-1788) in mouse cerebral cortex. The increase of peripheral benzodiazepine binding sites on brain and heart cryostat cut slices caused by stress was also antagonized by pretreatment with medetomidine. The behavioural and biochemical data obtained in this study are evidence that medetomidine does not have anxiolytic effect but may have, in lower doses, stress-protective activity.

Activation of excitatory amino acid inputs to supraoptic neurons. I. Induced increases in dye-coupling in lactating, but not virgin or male rats

Mitral cells of the main and accessory olfactory bulbs have been shown to project monosynaptically to the supraoptic nucleus (SON) via the lateral olfactory tract (LOT) which uses excitatory amino acid transmitters. Data collected during characterization of these projections suggested that synaptic activation of SON neurons via LOT stimulation in slices influence the incidence of dye-coupling. The present study pursued this suggestion using horizontally cut slices from male, virgin female and lactating rats. Neurons were confirmed to be excited by electrical stimulation of the tract, injected with Lucifer yellow, and synaptically activated for 10 min at 10 Hz (n = 92). Another 94 neurons were similarly confirmed and injected, but received no further stimulation. In an additional 8 slices, injected neurons were antidromically activated for 10 min at 10 Hz. Analyses done on 194 injected neurons from the 3 groups showed that synaptic activation resulted in a significant (P < 0.01) increase in the incidence of coupling only in tissue from lactating rats. This increase was entirely due to larger numbers of cells being coupled dendrodendritically to the injected cells in the stimulated slices. Antidromic activation did not influence coupling. Increased coupling occurred among both oxytocin and vasopressin cell types. This is the first report of increased coupling resulting from synaptic activation in mammalian CNS. Changes seen only in lactating rats may be related to their altered SON ultrastructural morphology (i.e. dendritic bundling). Strong olfactory and vomeronasal input associated with some maternal behaviors may increase neuronal coupling and enhance hormone release in response to other incoming stimuli (e.g. suckling, dehydration).

Human and animal fat cell size determination using an image analyzing computer

An automatization of the fat cell's morphological parameters determination with an image analyzing computer is proposed. The results obtained with this technique are compared to results obtained from the usual methods. Combined with frozen cut slices of adipose tissue, this automatized determination of fat cell size is well adapted for the large number of samples necessary for a specialized hospital service.

A new instrument for the rapid preparation of tissue slices

A manually operated microtome for the rapid preparation of live tissue slices is described. The instrument operates submerged in an isotonic solution and incorporates an automatic mechanism for the removal of the cut slices which are gently carried by a stream of fluid to a strainer reservoir. An inexperienced operator can obtain circular slices of nearly identical thickness at a rate of one every 3 or 4 s. Mechanical trauma to the tissues is minimized and the temperature and oxygenation of the medium are easily controlled.

Oxygen striations in czochralski silicon crystals

A number of bars grown by CZ, with p-and n-type dopant, have been examined in order to verify that both macroscopic and microscopic segregation of Oxygen atoms is governed by a distribution coefficient higher than 1. The short range non uniformity of 0-atoms concentration has been revealed by preferential etching and spreading resistance measurements, the long range one by IR spectroscopy. A few degrees off orientation of cut slices enabled (as in the case of a beveling angle in junction structures) to expand the radial abscissa and to separate with a better definition the zones of higher 0-concentration. Using such a method, a shape of the profile of the S-L interface can be defined, at any point of the bar.

SENSORY QUALITIES OF SELECTED CANNED FOODS SUBJECTED TO SHORT–TERM STORAGE

ABSTRACTCanned asparagus cut, corn kernels, peas and apple slices were produced from respective frozen products, which were obtained from a local frozen food packer. Commercial processing procedures were followed for this production. Immediately after the production, the canned foods were randomly divided into five different lots and initiated storage at ‐29, 2, 4.5, 21 or 38°C for slightly over 1 yr. During this storage, the products were sampled at five different dates and subjected to the evaluation of overall sensory quality by a flavor panel. For this evaluation, those stored at ‐29°C were used as reference samples to determine flavor difference scores. It was generally observed that samples stored at 38°C deteriorated at considerably faster rates as compared to those stored at the lower temperatures. The storage at 2, 4.5 or 21°C did not result in severe loss of the quality during the entire test period. Changes in the flavor difference scores may be mathematically represented with polynominal functions of storage time and temperature according to the regression analysis of data collected.

Distribution of a behaviorally highly potent ACTH 4−9 analog in rat brain after intraventricular administration

Distribution within the brain of a 3-fold modified ACTH 4−9 analog with a remarkably potentiated behavioral activity, 4-Met (O 2), 8- d-Lys, 9-Phe-ACTH 4−9, was investigated. The radioactive labeled [7- 3H-Phe]ACTH 4−9 analog was administered intraventricularly in urethane anesthetized rats in a dose of approximately 170 ng. Total radioactivity in CSF, measured in samples drawn from the cisterna magna, decreased over the period 0.5–4 h after injection from 51 to 2% of the injected dose. Intraventricular injection of the ACTH 4−9 analog resulted in high intact peptide levels in the brain. At 2 h after injection the distribution of radioactivity over 2500 μm and 300 μm frontal cut brain slices was rather homogenous. Data from distribution studies over topographically defined gross brain structures indicated that the septal area, which is involved in eliciting behavioral activities of ACTH-like neuropeptides, accumulated most of the injected radioactivity per gram wet weight. The distribution profiles within the brain of the [ 3H]ACTH 4−9 analog and [ 3H]Phe showed considerable differences. Uptake studies in various brain nuclei after intraventricular administration of the [ 3H]ACTH 4−9 analog demonstrated that the greatest part of the investigated nuclei exhibited relative low or medium uptake of radioactivity. This was also true for hippocampal and thalamic nuclei, which have been suggested as effective sites of action for ACTH peptides. Very high accumulation of radioactivity occurred only in the septal nuclei, particularly the dorsal and fimbrial septal nuclei. The results indicate selective uptake of the ACTH 4−9 analog in the septal area, suggesting a possible significance of this area as a site of action of ACTH neuropeptides.

Glycoproteins of Cell Surfaces: A COMPARATIVE STUDY OF THREE DIFFERENT CELL SURFACES OF THE RAT

Abstract The glycoproteins of three different cell surface membranes of the rat have been investigated by acrylamide gel electrophoresis with the use of discontinuous buffers in the presence of sodium dodecyl sulfate (SDS). Liver, kidney brush border, and erythrocyte ghost membranes are solubilized in SDS and after brief exposure to dilute base are reduced with βmercaptoethanol. The gels, after washing free of SDS, are Schiff-stained, and it is demonstrated, by the use of glycoproteins of known molecular weight and subunit composition, that the stained patterns represent size separations of glycoprotein subunits. Each membrane is found to have an identifiable glycoprotein subunit pattern composed of at least 6 to 11 different sized subunits. Most of the staining intensity is present in one to three subunits. Although each membrane has its own unique pattern, liver and kidney brush border have four identically sized subunits. These subunits have molecular weights of 250,000, 195,000, 130,000, and 96,000 when estimated by interpolations of relative mobilities between protein markers. The erythrocyte ghost also contains a 96,000 molecular weight glycoprotein subunit. Sialic acid determinations made on cut gel slices show that all prominent Schiff-positive glycoproteins contain sialic acid.