Denna uppsats ar en hermeneutiskt inspirerad studie som undersoker hur dokumentarfilmskapare ljudlagger sina filmer och vilka intentioner som ligger bakom deras ljudlaggningar.
Genom kvalitativa i ...
Abstract DNA and RNA were studied in the layers of human prefrontal cortex by quantitative microchemical analyses on microtome‐prepared serial frozen sections. Eleven cortical specimens from six autopsy brains were assayed. The mean total number of cells per mm 3 of fresh cortex was estimated from DNA values. The number in layer I (61,000) was falsely high because of the inclusion of cells from the pia mater. From a plateau of 82,000‐86,000 in layers II, IIIa and IIIb, the number of cells rose to 91,000 and 113,000 in layers IIIc and IV, respectively. The mean number was slightly lower in layer V, then gradually rose through layer VI to 127,000 cells in white matter. Per unit dry weight, DNA and cells varied much less than per unit volume; values averaged 14 per cent higher in layers II and IV than in neighbouring layers and in white matter were 20 per cent lower than in layer I. Intracortical patterns of RNA and RNA/cell reflected chiefly the distribution of neuronal cell bodies. Per unit fresh volume, RNA roughly paralleled DNA in layers I‐V; through layer VI and into white matter RNA declined as DNA rose, reflecting the decline in neurons and increasing predominance of glial cells of lower RNA content. Per unit dry weight, RNA rose 50 per cent from layer I to layer II; a plateau of high values extended through layers II‐V, then RNA declined rapidly through layer VI to a level in white matter that was 28 per cent of the value in layer II. Mean RNA/cell in cortex was 9‐8 pg, with a maximum in layer IIIb (11.4 pg); in subcortical white matter it was 5.3 pg.
Abstract A new technique combining microfluorometric DNA assays with differential cell counts was used to quantitate the intralaminar distribution of neuronal and non‐neuronal cells (chiefly glial) in rat somatosensory cortex (Charles River 250 gm males, C D® strain). The intracortical amounts of DNA per unit fresh volume were calculated from the DNA contents of serial frozen slices of known volume sampled serially from the pial surface to white matter in frozen cortical cylinders; respective amounts per unit solids were calculated from predetermined dry weights of the slices. Cell counts were performed on serial horizontal sections from formalin‐fixed cylinders stained by Nissl's method. Neuronal DNA and glial DNA were calculated based on the percentages of the respective cells counted. Total DNA averaged 5.43 μg/mg dry weight (1.19 μg mm 3 fresh volume). Values were highest in layers II and IV. Neuronal DNA paralleled total DNA in its intracortical distribution and showed distinct peaks in layers II and IV. Glial DNA showed an even distribution. Glia exceeded neurons only in layers I and VIc. The mean neuron/glia ratio was 2.5. This method gives a more precise estimate of the absolute numbers of neurons and glia than can be obtained by histological methods alone, since DNA assays eliminate the need to correct the histological counts for volume changes during fixation and staining.
In pursuing quantitative histochemical investigations aimed at demonstrating the biochemical architecture of human frontal cortex (l-4), we found it necessary to determine ganglioside sialic acid in submicrogram amounts. Even when adapted to the microscale, spectrophotometric methods lack the sensitivity required for studying nervous tissue samples containing less than 0.3 pg of sialic acid. Since fluorometric methods usually possess a sensitivity 100to lOOO-fold that of spectrophotometric methods, the possibility of devising a fluorometric technique for sialic acid measurement was investigated. N-Acetylneuraminic acid of brain gangliosides is a 9 carbon or-keto acid. Such compounds readily undergo decarboxylation on treatment with hot mineral acids. Formation under such conditions of the deacylated, decarboxylated derivative of NAN,’ 2-deoxy-4-amino-octose, has been suggested by Gottschalk (5) as the basis for the reaction of NAN in (a) the diphenylamine test; (b) the resorcinol-HCl test; and (c) humin formation at concentrations of hot mineral acid as low as 0.1 N. The 2-deoxy sugars and in general aldehydes of the type R-CHZ-CHO will react wit,h 3,5-diaminobenzoic acid when heated in mineral acids to yield highly fluorescent quinaldines. The product of the Doebner and Von Miller quinoline synthesis involving acetaldehyde and 3,5-diaminobenzoic acid has been characterized by Velluz, Amiard, and Pesez (6), who also reported (7, 8) that deoxyribose and DNA undergo the reaction. The principle was applied subsequently to the ultramicro assay of DNA by Kissane and Robins (9), of succinic semialdehyde by Salvador and Albers (lo), and of 2-deoxy-n-glucose by Blecher (II). When NAN was heated at 100” under conditions similar to those used in the DNA method (9), a green fluorescent product was obtained, as described in a preliminary report (12). Hexoses, however, were serious interfering compounds in the method as it was originally carried out, presumably because an intermediate in the conversion of hexose to levulinic acid by hot mineral acids is w-OH-levulinic aldehyde, an a-methylene aldehyde (13). In a search for reaction conditions which would favor the synthesis of the sialic acid product over that of hexoses, systematic studies were made of the effects on the fluorescence yield of variations in 3,5-diaminobenzoic acid and HCl concentrations as well as in temperature and duration of the heating period. Conditions were found enabling reduction in the interference by hexoses t,o 1.6% on a molar basis. The sensitivity of t.he resulting method may be indicated by the fact that the
Quantitative microchemical analyses of biochemical structural components were performed on experimental astrocytomas produced by subcutaneous growth in hamsters of two hamster astroglial cell lines separately transformed in vitro by a DNA virus, polyoma. Tumors from Line 1 were well differentiated, those from Line 2 were anaplastic. Astrocytomas from both cell lines possessed characteristic astrocytic morphology, were free from contamination by other neural tissue elements and relatively free from necrosis. Expressed as a % of dry weight, the Line 2 tumors significantly exceeded the Line 1 tumors in content of DNA (3.13 and 2.28%), RNA (3.30 and 2.06%), phospholipid (6.94 and 5.08%), and residue protein (62.5 and 58.0%). The phospholipid: cholesterol molar ratios were 2.0 and 1.6 in the Line 2 and Line 1 tumors, respectively. Proteolipid protein comprised only 1% of the total protein content of the tumors. The mean content of ganglioside sialic acid in the tumors was 33–40% as great as in brain white matter, 17% as great as in gray matter. The molar ratio of ganglioside sialic acid to ceramide hexose averaged 1:6.3 in the anaplastic Line 2, and 1:3.9 in Line 1. The high levels of nucleic acids and low levels of phospholipids in the experimental tumors are similar to those reported in specimens of human spontaneous astrogliomas. The experimental subcutaneous tumors are an abundant source of cells for investigation of normal and neoplastic properties of astrocytes.
