Isolation of parietal cells from glutaraldehyde-fixed rabbit stomach

A method is introduced to isolate and purify parietal cells from the rabbit stomach which has been briefly perfused with 1% glutaraldehyde via the celiac artery. The fixed mucosa is initially digested with 1% trypsin and subsequently with 1% collagenase solution. The parietal cells are more resistant to the effects of these proteolytic enzymes than the other cell types in the gastric mucosa and can be recovered and purified by centrifugation in a discontinuous sucrose gradient. Glutaraldehyde fixation reduces the tendency of cell clumping and, therefore, facilitates isolation of the separated cells. The final yield from each adult rabbit stomach varies from 0.1 to 0.4 ml packed parietal cells of about 97% purity determined by nuclear counts. The nuclei and mitochondria of most of the isolated cells appear to be intact on electron micrographs, but the cell membrane is focally disrupted; the nuclear deoxyribonucleic acid (DNA) can be stained with Feulgen technique and extracted with perchloric acid for quantitative determination. Biochemical studies on incorporation of thymidine-3H into DNA of the parietal cells have been carried out in normal young adult rabbits and in rabbits under chronic histamine stimulation. The results show that there is no significant incorporation of thymidine-3H by mature parietal cells in any of the two groups of animals, although the whole mucosa DNA hydrolysates always exhibit a high specific activity.

Interferon inhibition of DNA synthesis and cell division

Using monodispersed cell suspensions, interferon preparations were shown to have both a lethal and a growth-depression effect in the same concentration range as that required for antiviral activity. In addition, synchronized cells treated with interferon respond by delaying their normal uptake of thymidine during S phase until after a period during which new protein is synthesized. Puromycin added during this period prevents both the synthesis of this protein and the subsequent synthesis of DNA.

Synthesis of a spatial filter for the combined operations of subtraction and correlation

As is known, a coherent optical data processing system can be used to perform convolution and correlation with ease. Recently it has been shown that the system with diffraction gratings in the spatial filtering plane can also add or subtract complex patterns displayed symmetrically in the input plane. A method is described here for synthesizing a spatial filter so that the coherent system can perform both correlation and subtraction simultaneously in real time. As a particular application of this technique, we present results of using such filters in optical feature extraction.

Matrix multiplication by optical methods

The utilization of coherent optical correlation techniques in the performance of matrix multiplication by-optical analog methods has been investigated mathematically. Although the basic concepts have been known for some time, we have not been able to find explicit analyses in the existing literature. Since many correlations other than those corresponding to the desired matrix multiplication terms exist, methods of isolating the desired from the undesired terms are presented. Various spatial configurations for both the input and output arrays are discussed. For the special cases of 2 x 2 matrices the analyses are presented in greater detail. Using simple circ function distributions, the effects of finite-sized array elements and detector apertures are investigated.

Variation of interferon production during the cell cycle

The capacity of cells to produce interferon has been found to depend on the phase in the cell cycle at which virus infection took place. Monolayer cultures of L cells were synchronized by the double thymidine-block method. Such synchronously growing cultures were used to study the ability of cells to produce interferon when they were infected with ultraviolet-inactivated Newcastle disease virus (UV-NDV) at different phases of the cell cycle. In all instances, interferon was detected early and reached a maximum at about 16 hr after infection. However, the levels of interferon found in medium of cultures infected at early post-deoxyribonucleic acid (DNA) synthetic (G2) and to some extent at late G2 phases of the cell cycle were comparatively lower than those found in cultures infected at the early DNA synthetic (S) phase. There appeared also in these infected growing cultures a transient period when interferon production was apparently delayed. This period corresponded interestingly with the time of mitotic burst. Infection of thymidine- or 1-beta-d-arabino-furanosylcytosine-inhibited cultures with UV-NDV also led to similar interferon response as that observed in growing cultures infected at early S. However, no transient delay of interferon production was demonstrated in these cultures.

Interferon production by human leukocytes in vitro: some biological characteristics

Interferon was optimally produced in human peripheral leukocyte cultures incubated for approximately 19 hr in the presence of Sendai virus at a multiplicity of 10 to 50 EID(50)/cell. For determining whether deoxyribonucleic acid (DNA) synthesis per se was essential for interferon production, 1-beta-D-arabinofuranosylcytosine (Ara-C), a potent DNA inhibitor was studied for its effect on interferon production in leukocytic and bone marrow cell cultures. These cells showed no impaired capacity to produce interferon when treated with 15 mug of Ara-C per ml. Interferon yields were also determined in leukocyte cultures treated with actinomycin D (0.1 mug/ml) and puromycin (10 mug/ml) at various times before and after virus inoculation. The data suggested that sequential transcriptive and translational events were required for the de novo synthesis of interferon by the infected leukocytes, in a manner similar to other known virus-induced interferon-producing systems. The synthesis of macromolecules and the effects of antimetabolites in leukocytes and bone marrow cell cultures were followed by measuring the incorporation of thymidine-2-(14)C, uridine-5-(3)H, and L-phenylalanine-1-(14)C. The effect of 0.1 mug of actinomycin per ml on the capacity of leukemic leukocytes to produce interferon was also studied. Preliminary data showed that, in contrast to nonleukemic leukocytes, interferon production by leukemic leukocytes was only partially inhibited by actinomycin.

Electron microscope studies of glutamic oxalacetic transaminase in rat liver cell

Liver tissue of the rat, fixed in glutaraldehyde and formaldehyde, was incubated in a medium which consisted of 20 mML-aspartic acid, 2 mM alpha-ketoglutaric acid, 50 mM imidazole and 6 mM lead nitrate at pH 7.2-7.4. The electron-opaque precipitates, due to glutamic oxalacetic transaminase activity in liver cells, were found to be localized to the cristae and surface membranes of the mitochondria, the limiting membrane of the microbodies, and the nuclear membrane. Sucrose storage and trauma resulted in altered morphology and diminished final product intensity in mitochondria, but the microbody enzyme activity disappeared completely under these conditions. These distinctive responses of enzymatic activity are considered to indicate a difference in either the enzyme protein or its membrane attachment to these two sites. The use of a buffered dehydrating ethanol series to prepare tissue blocks for electron microscopy appeared to result in more precise intracellular localization of enzymatic reaction product.

A biochemical and histochemical study of glutamic oxalacetic transaminase activity of rat hepatic mitochondria fixed in situ and in vitro

Rat liver perfused in situ briefly with a glutaraldehyde-formaldehyde mixture was homogenized in isotonic sucrose. The mitochondria, isolated from a homogenate of the perfused liver by differential centrifugation, assumed a slender and compact appearance similar to those often seen in an intact cell. The glutamic oxalacetic transaminase (GOT) activity of this mitochondrial fraction survived an additional formaldehyde fixation and was studied by biochemical and histochemical methods. The biochemical assay of the enzyme activity revealed that the activity was only slightly less than that of an unfixed mitochondrial fraction. The reaction product due to mitochondrial GOT activity was found to be localized to the cristae, as had been demonstrated in an intact liver cell. GOT activity of the mitochondrial fraction isolated from fresh liver tissue homogenate in 0.25 M sucrose was inactivated readily by either glutaraldehyde or formaldehyde and was no longer demonstrable by biochemical and histochemical methods after fixation.

The effects of lead and fixatives on activity of glutamic oxalacetic transaminase

Lead oxalacetate, a primary reaction product precipitate for the visualization of the activity of glutamic oxalacetic transaminase in tissue sections, is stable at a slightly alkaline pH. At concentrations which are used for tissue fixation a slight inhibitory effect on glutamic oxalacetic transaminase activity is produced by acetone while a glutaraldehyde-formaldehyde mixture results in marked reduction of activity. The concentration of lead which is used to form the primary reaction product does not significantly inhibit this enzyme activity.

Vaccinia gangrenosa and 1-methylisatin 3-thiosemicarbazone (methisazone)

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In vitro autolysis of plant cell walls

Primary cell walls of Zea mays prepared in a glycerol medium are capable of autolysis in vitro. Autolysis results in solubilization of about 10% of the wall substance during an 8 hour incubation period. Approximately 10% of the solubilized material is glucose and the remainder consists of an unidentified polymer which yields only glucose upon hydrolysis. Cell wall autolysis is a linear function of time of incubation and of wall concentration. The autolytic process occurs optimally over the pH range of 5.5 to 6.5. The possible relationship between autolytic capacity and capacity for elongation is discussed.

Fatal primary Epstein-Barr virus infection masquerading as histiocytic medullary reticulosis in young children in Taiwan

We reported 3 fatal cases of primary Epstein-Barr virus (EBV) infection resembling histiocytic medullary reticulosis (HMR) in young children in Taiwan, where an HMR-like illness has been previously found to be prevalent. The disease ran a fulminant course, manifesting as fever, anemia, jaundice, skin rash, pulmonary infiltration, and/or hepatosplenomegaly lasting for only 1-3 weeks. Laboratory tests revealed no hemolytic anemia and Coombs test was negative. Sepsis or HMR was the main clinical differential. At autopsy, the spleen, liver, lymph node, lung, and bone marrow showed infiltration of atypical "histiocytes" or blasts, lymphocytes, and mature histiocytes with hemophagocytosis. Immunophenotype and gene rearrangement studies of the lymphoid tissues revealed that these atypical "histiocytes" were actually polyclonal B immunoblasts in one case and transformed T lymphocytes in the remaining 2 cases, representing two different types of virus-host interaction. Southern blot and in situ hybridization studies on frozen lymphoid tissues demonstrated the presence of EBV DNA in all 3 patients; the study for cytomegalovirus was negative. The young age of these patients, closely correlated with the prevalent age of primary EBV infection in the general populations in Taiwan, strongly suggest that these childhood cases of previously diagnosed HMR-like disease may actually represent a lethal form of primary EBV infection or fatal infectious mononucleosis.