Biomedical subjects
Publications and source records attributed to A Peters.
It was attempted to improve the resolution of the 2-deoxyglucose method. Two principle changes in the procedure were introduced: the gluing of the sections on to the object slide at--20 degrees C and the application of the emulsion with the loop technique. With this approach autoradiographs with grain accumulations over single cell bodies could be observed in many brain regions in addition to a diffuse activity over neuropil.
When the corpus callosum of the rat is sectioned, the callosal fibres in the cerebral cortex undergo degeneration. In the auditory cortex (area 41) the degenerating axon terminals form asymmetric synapses, and the vast majority of them synapse with dendritic spines. Some other synapse with the shafts of both spiny and smooth dendrites, and a few with the perikarya of non-pyramidal cells. The degenerating axon terminals are contained principally within layer II/III, in which they aggregate in patches. Using a technique in which neurons within the cortex are Golgi-impregnated, then gold-toned and examined in the electron microscope, it has been shown that the dendritic spines of pyramidal neurons with cell bodies in different layers receive the degenerating callosal afferents. The spines arise from the main apical dendritic shafts and their branches, from the dendrites of the apical tufts, and in some cases from the basal dendrites of the pyramidal neurons. The shafts of some pyramidal cell apical dendrites also form asymmetric synapses with callosal afferents. Since we have encountered no spiny non-pyramidal neurons in Golgi preparations of rat auditory cortex, and because other types of non-pyramidal cells have few dendritic spines, it is concluded that practically all of the dendritic spines synapsing with callosal afferents originate from pyramidal neurons.
A rapid and reliable method for the quantitative determination of cefmenoxime in serum and urine by reversed phase high-performance liquid chromatography is described. Serum was deproteinized with acetonitrile. Urine was diluted with dilute acetic acid (17.5 mmol/l). Separations were performed in isocratic mode using a C18 type column and a precolumn packed with Perisorb RP/8. The eluant consisted of a mixture of acetonitrile and 25.0 mmol/l acetic acid in a ratio of 32/69 (vol/vol). In normal subjects cefmenoxime was well separated from endogenous compounds and various added drugs. Its complete separation was confirmed by selective degradation with beta-lactamase from Bacillus cereus and UV spectrophotometry. The detection limit was 0.3 mg/l at a detection wave-length of 254 nm. Peak areas gave linear results up to concentrations of 500 mg/l. Within-batch precision (coefficient of variation) ranged from 1.1 to 6.2%. Recovery rates varied from 99.0 to 103.3%. Results of a standard microbiological assay correlated well with those obtained by the present HPLC method. Eight healthy volunteers who were given a single intravenous dose of 1 g cefmenoxime excreted 86.3 +/- 5.8% of the unchanged drug within 24 h in urine.
The brains of Sprague-Dawley rats in various age groups from 3 to 33 months were fixed by perfusion with standard aldehyde solutions in order to determine the effects of aging on neuronal numbers. Several indices of cortical volume were then measured to determine whether neuronal packing densities were affected by age-related change in cortical volume. The lengths, heights and widths of individual hemispheres for 160 animals ranging in age from 1 day to 36 months were first determined, after which blocks of tissue were removed from area 17 of some of the brains. These blocks were osmicated, embedded in Araldite and sectioned at 1 micrometer to ascertain, in the vertical plane, the thickness of area 17 and, in the tangential plane, the packing density of the clusters of apical dendrites extending from layer V pyramidal neurons. Results indicate the overall dimensions of the cerebral hemispheres increased until 3 months of age, after which there was no further increase in size. Between 3 and 33 months of age there was no age-related change in either the thickness of area 17 or in the separation between dendritic clusters, indicating the volume of area 17 did not change after 3 months of age. Within individual age groups the amount of variation present is greater than that among age groups. Since the number of nucleus-containing neuronal profiles per unit area of layers II/III, IV, V, VIa and VIb was similar in two groups of three animals at 3 and 33 months of age and the diameters of neuronal nuclei were unchanged, there seems to be no significant change in the number of neurons contained in these layers of rat visual cortex between 3 and 33 months of age. It is therefore concluded that no neurons are lost from area 17 as the mature cerebral cortex ages.
High-dose cytoreductive treatment followed by ABMT represents a new approach to the treatment of acute leukemia as an alternative when leukemic patients do not have HLA-identical donors. ABMT protocol seems to be a valuable treatment for AML if it is immediately employed after the remission obtained to consolidate the remission. For ALL adult patients, and so for poor prognosis ALL in children, intensive therapy with ABMT represents a new approach when conventional therapy has failed or failed to consolidate the remission. The results of ABMT in CML in the literature have been disappointing; the bone marrow could be collected during the course of the first chronic phase after hydroxyurea therapy or other treatment programs. In leukemia the ABMT approach will be more credible if the protocol includes in vitro immunologic or pharmacologic means to eliminate residual leukemic cells.
The distribution and form of cholecystokinin immunoreactive neurons in neocortical areas within the posterior pole of the rat cerebral hemisphere was examined using the immunoperoxidase technique. Although cholecystokinin-positive neurons are present throughout the cortex, they are most frequent in the supragranular layers. These neurons are of three kinds: layer I neurons, bipolar cells, and other non-pyramidal cells with either multipolar or bitufted dendritic trees. In electron-microscopic preparations, the horseradish peroxidase reaction product is found to form a granular deposit which occurs throughout the cytoplasm and nucleoplasm and shows no predilection for any particular type of organelle. Electron-microscopy also shows cholecystokinin-positive neurons to have both symmetric and asymmetric synapses on their perikarya, which is additional evidence in favor of the interpretation that they are non-pyramidal cells. In the light-microscopic preparations three types of CCK-positive axons are encountered. These are vertically-oriented axons considered to arise from bipolar cells, a plexus in the superficial portion of layer II/III which is believed to arise from the multipolar and bitufted cells, and a deep plexus of unknown origin in layers VI and V. Since the axons of bipolar cells form asymmetric synapses they are thought to be excitatory neurons. In contrast, the bitufted and multipolar neurons are probably inhibitory, for previous studies have shown neurons with similar features to have axons which form symmetric synapses and to contain glutamic acid decarboxylase. Thus, although iontophoretically-applied cholecystokinin excites cortical neurons, it appears to be present in some neurons which are excitatory and others which are inhibitory.
The technique using the IBM 2991 blood cell processor is an effective technique for the concentration of mononuclear cells from large volumes of bone marrow. The marrow cells are layered on to Ficoll Metrizoate using the IBM processing set. The mononuclear cells and CFU-GM recoveries are in close relationship with the hematocrit of the cell suspension processed. Twenty two bone marrows have been collected and purified according to this protocol. The mononuclear cell recovery is an average of 78,3% (range: 44-92%) and the CFU-GM recovery is in average of 67,5% (range: 40-89%). At the end of the procedure the cell viability is satisfying (97,1% +/- 1,7 are trypan blue negatives). When it is necessary to remove from the bone marrow collected either malignant cells prior autologous bone marrow graft or T lymphocytes in an attempt to prevent GVHD in allogeneic BMT, the purity of marrow cell suspension become a fundamental parameter.
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In bovine, the intermediate lobe is highly active and the holocrine secretion of its marginal cell layer forms a colloid-like substance housed in the intra-glandular cleft (residual lumen). Immunodiffusion of fractions of intraglandular colloid shows determinants sharing antigenic specificity with GH, FSH, CSF and serum immunoglobulins. The fractions tested by PAGE show determinants common to intraglandular colloid, CSF and serum albumin. The intraglandular cleft housing intermediate lobe colloid communicates by well defined channels passing through the intermediate lobe with the subarachnoid space, and with the cavernous sinuses by well defined venous channels. The venous channels are provided with well developed valve-like structures preventing venous blood from entering the cleft. These results question the relationship of the blood-brain barrier to the transport of pituitary substances. It is known that some pituitary peptide hormones (e.g. GH, ACTH, etc.) cannot cross the blood-brain barrier and their concentration in the CSF may not be due to an impairment of the barrier. We contend that intraglandular colloid of intermediate lobe origin is a part of major pituitary transport system and, fluctuating hormones and immunoglobulins in the CSF may be due to direct contributions from the pituitary.
Bovine pituitary intraglandular colloid is formed by the cyclic degeneration of marginal cells lining the intermediate lobe and is housed in the intraglandular lumen (residual lumen). The lumen communicates with the subarachnoid cerebrospinal fluid space by well defined channels. Electrophoresis in acrylamide gel shows bovine pituitary intraglandular colloid as having double protein bands identical to the protein in bovine and human cerebrospinal fluid. These studies demonstrate two distinct bands in the gamma region for colloid, not apparent in the normal bovine or human cerebrospinal fluid due to the low concentration of gamma globulins. We conclude that pituitary colloid, laden with immunoreactive fragments of various pituitary hormones, is discharged from the hypophyseal intraglandular space, directly into the subarachnoid cerebrospinal fluid space.
Bovine hypophyseal intraglandular colloid, the holocrine secretion of marginal intermediate lobe cells, contains high molecular weight (MW 45 000 to 158 000) protein fractions and low molecular weight (MW below 25 000) peptide fractions. The fractions display immunoreactive determinants similar to those in pituitary hormones, cerebrospinal fluid (CSF), serum IgG and albumin. Immunoelectrophoresis shows that components in high molecular weight fractions distribute themselves in three distinct bands (gamma, beta, alpha), while those in low molecular weight fractions distribute themselves in two bands (gamma and alpha). Physiochemical characteristics, i.e., sedimentation rate, percentage of hexose, total CHO and 12C as well as the content of cystine are presented. It is concluded that pituitary colloid should not be dismissed as a waste product of cellular degeneration, since there are strong suggestions that it serves as a transport medium for certain pituitary hormones.
Golgi-impregnated chandelier cells in rat visual cortex have been examined by both light and electron microscopy. All of the chandelier cells impregnated have their cell bodies within layer II/III and although they occur throughout area 17, there are increased numbers at the area 17/18a border and to a lesser extent at the area 17/18 border. Most of the chandelier cells are bitufted neurons, with groups of dendrites extending from the upper and lower poles of an elongate cell body, but some cells have a more multipolar configuration. The perikaryal cytoplasm is rich in rough endoplasmic reticulum and both the cell body and the sparsely spinous dendrites receive axon terminals forming symmetric and asymmetric synapses. The axons of these neurons arise from either the lower pole of the cell body or the base of one of the dendrites in the lower tuft, and the axons form laterally spread plexuses which terminate in vertical strings of boutons. The boutons in each string synapse with axon initial segments of layer II/III pyramidal cells, the uppermost bouton in each string being 7 to 14 micrometers distant from the pyramidal cell body. Some layer II/III pyramidal cells seem to receive boutons from more than one chandelier cell, others from a single chandelier cell, and still other appear to receive no chandelier cell terminals. The axon terminals of the chandelier cells are irregular in shape, contain pleomorphic synaptic vesicles, and form symmetric synapses. Evidence is presented to show that axon terminals exhibiting the same morphological features and site of synaptic termination as those of the chandelier cells contain glutamic acid decarboxylase (GAD), the enzyme which synthesizes GABA. Hence the chandelier cells are probably GABAergic, inhibitory neurons. Other GAD-positive axon terminals synapse with the cell bodies, axon hillocks, and proximal portions of the axon initial segments of the layer II/III pyramidal cells, and these terminals are probably derived from the smooth and sparsely spinous stellate cells.
The volumetric polymerization shrinkage of some composite resin restorative materials was measured with a modified dilatometer. It is emphasized that only the shrinkage from the start of the gelation, the rigid contraction of the material, is of clinical relevance. The amount of gelation was determined with an instrument that indicates the first moment at which the setting material is rigid enough to exert tensile forces. In addition, the influences of storage, testing conditions, and mixing ratio on the rigid contraction were studied for one light-cured as well as some chemically cured composite resins.
The centrifugation constitutes a fundamental stage in the blood components preparation as fresh frozen plasma and platelets rich plasma. The measure of the total effect of centrifugation (VT) is achieved with an integrator "w2dt". This parameter characterizes, in an unique way, the preparation procedure of a blood component. The value VT is determined and then sticked on the integrator, which made the rotation stop as soon as the preselected effect of centrifugation is reached. Thanks to this accessory, the authors have analysed the relative importance of the three data: acceleration, constant speed and deceleration, on the total effect of centrifugation. This analysis has induced them to a new approach of the centrifugation. For the authors, the classic notion of rotation time at constant speed, become insufficient. In blood transfusion, several applications are possible. The authors have determined the optimal conditions of platelets rich plasma (yield higher than 80% during a minimum real time) and platelets concentrate preparation with two different centrifuges, Sorvall RC3B and Jouan K 110 SX, equipped with Sorvall Integrator. The reproductibility of the experiments is satisfying when the centrifuged weight is comparatively constant. The standardization of centrifugation technics will be easier when the rotation radius will be included in the calculation of the total effect of centrifugation, thanks to integration.
Although it is over 30 years since an excess of bladder cancer was first identified in British rubber workers, the fear has persisted that this hazard could still be affecting men working in the industry today. Furthermore, suspicions have also arisen that other and hitherto unsuspected excesses of cancer might be occurring. For these reasons 33 815 men, who first started work in the industry between 1 January 1946 and 31 December 1960, have been followed up to 31 December 1975 to ascertain the number of deaths attributable to malignant disease and to compare these with the expected number calculated from the published mortality rates applicable to the male population of England and Wales and Scotland. The findings confirm the absence of any excess mortality from bladder cancer among men entering the industry after 1 January 1951 (the presumed bladder carcinogens were withdrawn from production processes in July 1949), but they confirm also a statistically significant excess of both lung and stomach cancer mortality. A small excess of oesophageal cancer was also observed in both the tyre and general rubber goods manufacturing sectors. American reports of an excess of leukaemia among rubber workers receive only limited support from the present study, where a small numerical excess of deaths from leukaemia is not statistically significant. A special feature of the study is the adoption of an analytical method that permits taking into account the long latent period of induction of occupational cancer.
Tissue removed from 3, 6, 9, 12, 15, and 21-day-old rats has been prepared for correlative light and electron microscopy to examine the maturation of cell bodies, dendrites, and axons of pyramidal neurons in layer V of rat visual cortex. As the size of the cell body increases steadily during the first 3 postnatal weeks there is an equivalent growth in nuclear volume. By day 15, there are infoldings in the nuclear envelope which may be induced by eye opening on day 14. Nucleoli increase in size until day 9, after which they appear to condense. Within the perikarya, the most conspicuous change is the amount and organization of the rough endoplasmic reticulum. Symmetric axosomatic synapses are evident by day 6. The ultrastructure of dendrites does not change substantially with age. Dendrites form synapses with symmetric densities as early as day 3 and asymmetric ones by day 9. It seems that dendritic spines begin as low, broad protrusions having symmetric junctions with smaller diameter axonal processes. With time they become taller stumps, before acquiring their mature lollipop shape and participating in asymmetric synapses with axonal varicosities. Other dendritic appendages, filopodia, and growth cones are transient structures, being conspicuous only between days 3 and 12. "Terminal" growth cones are essential for extension of dendritic processes, whereas "en passant" growth cones and filopodia seem important for dendritic branching. Boutons of mature pyramidal cell axons form asymmetric synapses with dendritic shafts and spines, but the developing synapses formed by these axons have more symmetric junctions. The maturation of pyramidal cell features progresses in concert with such extrinsic determinants as afferent input and is probably influenced by the competency of synaptic connections.