scholarly journals Inhibition by insulin of the formation of autophagic vacuoles in rat liver. A morphometric approach to the kinetics of intracellular degradation by autophagy.

1978 ◽  
Vol 78 (1) ◽  
pp. 152-167 ◽  
Author(s):  
U Pfeifer
Keyword(s):  
Half Life ◽  
Intraperitoneal Administration ◽  
Male Rats ◽  
Electron Microscopic ◽  
Autophagic Vacuoles ◽  
Intracellular Degradation ◽  
First Order Kinetics ◽  
Different Types ◽  
Electron Microscopic Morphometry ◽  
Kinetics Of

Electron microscopic morphometry has demonstrated a rapid decrease in the fractional volume of autophagic vacuoles (AV) in hepatocytes of adult male rats after the intraperitoneal administration of insulin (5 U/kg of body weight). Except for a significant decrease in glycogen to about one-half its initial value, no major changes in the composition of the remaining cytoplasm, or in the average volume of the single hepatocyte, were seen. The decrease found in the AVs is attributed to an inhibition of the formation of new AVs-probably the morphologic counterpart of the well-known anticatabolic effects of insulin. The decay of the fractional volume of the AVs appeared to follow first-order kinetics. Thus, the termination of the "life" of an AV by destruction of its contents may not depend directly on the "age" of the AV. The average half-life of the AVs amounted to approximately 9 min. Similar values were found for the different types of AVs, except for those containing glycogen. The half-life of these AVs was approximately 18 min. From the half-life values and from the "segregated fractions" at time zero, which were different for the different cytoplasmic components, rates of removal from the cytoplasm by autophagy were calculated. Expressed as "percent per day", the following rates were found: whole cytoplasm, 2.3; mitochondria, 3.9; microbodies, 8.9; and glycogen, 1.1. The results indicate that autophagy, to some extent, is selective and plays an important, but not an exclusive, role in intracellular turnover.

scholarly journals Equations describing the effects of the transient stability of subpopulations of nascent hnRNAs on the kinetics of turnover of hnRNA

1986 ◽  
Vol 233 (3) ◽  
pp. 905-908
Author(s):  
K C Kleene
Keyword(s):  
Half Life ◽  
Transient Stability ◽  
Precise Description ◽  
Electron Microscopic ◽  
First Order ◽  
First Order Kinetics ◽  
Microscopic Studies ◽  
Rate Of Decay ◽  
Kinetics Of ◽  
Continuous Labelling

The equations that have been used previously to analyse the rate of decay of hnRNA implicitly assume that nascent hnRNAs are degraded stochastically. This assumption is inconsistent with electron-microscopic studies of transcription cited here, which show that nascent hnRNAs are not degraded during transcription, implying that hnRNA degradation occurs only after termination of transcription and release of the hnRNA from chromatin. Equations are derived describing the accumulation of radioactivity hnRNA during continuous labelling assuming that nascent hnRNAs are stable and that hnRNAs decay with first-order kinetics only after completion of transcription. The effects of the transient stability of nascent hnRNAs on the kinetics of hnRNA turnover can become important when the half-life of the hnRNA is shorter than the time to transcribe an hnRNA from the point of initiation to the point of termination. These equations should prove useful in studies of hnRNA turnover that require a precise description of the labelling kinetics of nascent and completed subpopulations of hnRNA.

scholarly journals Dye removal abilities of the mesophilic and thermophilic biomass: a kinetics study

2018 ◽  
Vol 20 (2) ◽  
pp. 408-416
Keyword(s):  
Intraparticle Diffusion ◽  
Second Order ◽  
Intraparticle Diffusion Model ◽  
First Order Kinetics ◽  
Different Types ◽  
Pseudo Second Order ◽  
Acidic Conditions ◽  
Red Dye ◽  
Experimental Kinetics ◽  
Kinetics Of

Mesophilic biomass and thermophilic biomass samples were isolated and used to remove Dorasyn Red dye from aqueous solutions. The biosorption kinetics of dye uptake by four different types of biomass at three temperatures (20, 30, and 40 °C) were investigated using pseudo-first order kinetics, pseudo-second order kinetics, intraparticle diffusion, Elovich, and Bangham models. The pseudo-second-order kinetics model and the first stage of the intraparticle diffusion model were effective in describing the experimental kinetics data. The biosorption results showed that the mesophilic biomass samples could be useful for removing dye under acidic conditions.

Brain distribution and kinetics of desipramine in the rat

1981 ◽  
Vol 59 (2) ◽  
pp. 163-167 ◽  
Author(s):  
P. D. Hrdina ◽  
T. C. Dubas
Keyword(s):  
Single Dose ◽  
Peak Plasma ◽  
Intraperitoneal Administration ◽  
Brain Homogenate ◽  
Repeated Administration ◽  
Pharmacological Action ◽  
Male Rats ◽  
Brain Distribution ◽  
Kinetics Of ◽  
Critical Portion

Pharmacokinetics and regional as well as subcellular brain distribution of desipramine (DMI) were investigated in male rats after single and repeated intraperitoneal administration. After a single dose DMI enters brain rapidly, accumulates with increasing the dose, and attains concentrations about 20 times those seen in plasma. After repeated administration peak plasma and brain levels were 2.7 and 3.7 times, respectively, higher than after a single dose. No significant regional differences were found in brain distribution or disappearance half-lives of the drug. After chronic treatment the drug was preferentially retained in the P2 fraction of brain homogenate; this may reflect the critical portion of drug bound to sites responsible for its pharmacological action.

scholarly journals CELL SURFACE IMMUNOGLOBULIN

1974 ◽  
Vol 139 (4) ◽  
pp. 862-876 ◽  
Author(s):  
Ellen S. Vitetta ◽  
Inge Grundke-Iqbal ◽  
Kathryn V. Holmes ◽  
Jonathan W. Uhr
Keyword(s):  
Cell Surface ◽  
Half Life ◽  
Plasma Cells ◽  
Electron Microscopic Examination ◽  
Lymphoid Cells ◽  
Electron Microscopic ◽  
Igg Synthesis ◽  
Antigen Antibody ◽  
And Control ◽  
Kinetics Of

Lymphoid cells from the spleen, lymph nodes, and thoracic duct of axenic and control mice were incubated with [3H]tyrosine and synthesis and secretion of protein and Ig studied. It was found that only IgM was synthesized by cells from axenic mice whereas cells from control mice also synthesized IgG. Splenocytes from both axenic and control mice had 8S IgM on their surface. Radiolabeled splenocytes from axenic mice were incubated to determine the kinetics of release of 125I-labeled cell surface IgM and [3H]tyrosine-labeled IgM. Cell surface IgM was shed as 8S with an initial half-life of release of 5–8 h whereas [3H]tyrosine-labeled Ig was secreted as 19S with an initial half-life of 2–3 h. These findings suggest that two independent pathways are involved. It is suggested that small lymphocytes shed 8S IgM and plasma cells secrete 19S IgM. It was observed that lymphoid cells from axenic mice synthesize a higher proportion of IgM relative to total protein. Electron microscopic examination of splenocytes from such mice revealed a markedly higher proportion of plasma cells and a paucity of lymphoblasts compared to controls. It was suggested, therefore, that axenic mice lack a population of stimulated T cells which can induce a switch from IgM to IgG synthesis and which is capable of suppressing IgM synthesis. Lymphoid cells from axenic mice synthesize and secrete less protein that coprecipitates with antigen-antibody complexes.

The Morphology of the Rat Kidney Following Folic Acid Administration

1970 ◽  
Vol 28 ◽  
pp. 200-201
Author(s):  
Aline Byrnes ◽  
Elsa E. Ramos ◽  
Minoru Suzuki ◽  
E.D. Mayfield
Keyword(s):  
Folic Acid ◽  
De Novo ◽  
Specific Activity ◽  
Rat Kidney ◽  
Present Report ◽  
Intracellular Localization ◽  
Male Rats ◽  
Renal Hypertrophy ◽  
Electron Microscopic ◽  
Biochemical Alterations

Renal hypertrophy was induced in 100 g male rats by the injection of 250 mg folic acid (FA) dissolved in 0.3 M NaHCO3/kg body weight (i.v.). Preliminary studies of the biochemical alterations in ribonucleic acid (RNA) metabolism of the renal tissue have been reported recently (1). They are: RNA content and concentration, orotic acid-c14 incorporation into RNA and acid soluble nucleotide pool, intracellular localization of the newly synthesized RNA, and the specific activity of enzymes of the de novo pyrimidine biosynthesis pathway. The present report describes the light and electron microscopic observations in these animals. For light microscopy, kidney slices were fixed in formalin, embedded, sectioned, and stained with H & E and PAS.

Methionine-Specific Staining of Collagen

1982 ◽  
Vol 40 ◽  
pp. 294-295
Author(s):  
E.M. Kuhn ◽  
K.D. Marenus ◽  
M. Beer
Keyword(s):  
Amino Acids ◽  
Collagen Fibers ◽  
Type Iii Collagen ◽  
Type I ◽  
Electron Microscopic ◽  
Good Correspondence ◽  
Specific Staining ◽  
Type Iii ◽  
Different Types ◽  
Sulfur Containing

Fibers composed of different types of collagen cannot be differentiated by conventional electron microscopic stains. We are developing staining procedures aimed at identifying collagen fibers of different types.Pt(Gly-L-Met)Cl binds specifically to sulfur-containing amino acids. Different collagens have methionine (met) residues at somewhat different positions. A good correspondence has been reported between known met positions and Pt(GLM) bands in rat Type I SLS (collagen aggregates in which molecules lie adjacent to each other in exact register). We have confirmed this relationship in Type III collagen SLS (Fig. 1).

The Effect of Androgen Depletion and Replacement on the Epithelium of the Seminal Vesicle of the Aging Rat

1975 ◽  
Vol 33 ◽  
pp. 590-591
Author(s):  
Venita F. Allison
Keyword(s):  
Cell Proliferation ◽  
Seminal Vesicle ◽  
Male Rats ◽  
Target Cells ◽  
Cell Regeneration ◽  
Secretory Function ◽  
Electron Microscopic ◽  
Aging Rat ◽  
Microscopic Studies ◽  
Androgen Depletion

In 1930, Moore, Hughes and Gallager reported that after castration seminal vesicle epithelial cell atrophy occurred and that cell regeneration could be achieved with daily injections of testis extract. Electron microscopic studies have confirmed those observations and have shown that testosterone injections restore the epithelium of the seminal vesicle in adult castrated male rats. Studies concerned with the metabolism of androgens point out that dihydrotestosterone stimulates cell proliferation and that other metabolites of testosterone probably influence secretory function in certain target cells.Although the influence of androgens on adult seminal vesicle epithelial cytology is well documented, little is known of the effect of androgen depletion and replacement on those cells in aging animals. The present study is concerned with the effect of castration and testosterone injection on the epithelium of the seminal vesicle of aging rats.

Toxic effects of inhaled DMMP on the kidneys of Fischer-344 rats

1987 ◽  
Vol 45 ◽  
pp. 880-881
Author(s):  
D.R. Mattie ◽  
C.J. Hixson
Keyword(s):  
Left Kidney ◽  
Inhalation Exposure ◽  
Electron Microscopic Examination ◽  
Exposure Period ◽  
Male Rats ◽  
Continuous Exposure ◽  
Fischer 344 Rats ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Fischer 344

Dimethylmethylphosphonate (DMMP) is a simple organophosphate used industrially as a flame retardant and to lower viscosity in polyester and epoxy resins. The military considered the use of DMMP as a nerve gas simulant. Since military use of DMMP involved exposure by inhalation, there was a need for a subchronic inhalation exposure to DMMP to fully investigate its toxic potential.Male Fischer-344 rats were exposed to 25 ppm or 250 ppm DMMP vapor on a continuous basis for 90 days. An equal number of control rats were sham-exposed. Following the 90-day continuous exposure period, 15 male rats were sacrificed from each group. Two rats from each group had the left kidney perfused for electron microscopic examination. The kidneys were perfused from a height of 150 cm water with 1% glutaraldehyde in Sorensen's 0.1M phosphate buffer pH 7.2. An additional kidney was taken from a rat in each group and fixed by immersion in 2.5% glutaraldehyde and 2% paraformaldehyde in 0.1M cacodylate buffer pH 7.4. A portion of the 9 kidneys collected for electron microscopy were processed into Epon 812. Thin sections, stained with uranyl acetate and lead citrate, were examined with a JEOL 100B Transmission Electron Microscope. Microvilli height was measured on photographs of the cells of proximal tubules. This data, along with morphologic features of the cells, allows the proximal convoluted tubules (PCT) to be identified as being S1, S2, or S3 segment PCT.

Electron microscopic characterization of diamond thin films and substrates for diamond heteroepitaxial growth

1989 ◽  
Vol 47 ◽  
pp. 592-593
Author(s):  
J.B. Posthill ◽  
R.P. Burns ◽  
R.A. Rudder ◽  
Y.H. Lee ◽  
R.J. Markunas ◽  
...  
Keyword(s):  
Thin Films ◽  
Wide Band ◽  
Deposition Process ◽  
Heteroepitaxial Growth ◽  
Electron Microscopic ◽  
Wide Band Gap ◽  
Lattice Matching ◽  
Different Types ◽  
Diamond Thin Films

Because of diamond’s wide band gap, high thermal conductivity, high breakdown voltage and high radiation resistance, there is a growing interest in developing diamond-based devices for several new and demanding electronic applications. In developing this technology, there are several new challenges to be overcome. Much of our effort has been directed at developing a diamond deposition process that will permit controlled, epitaxial growth. Also, because of cost and size considerations, it is mandatory that a non-native substrate be developed for heteroepitaxial nucleation and growth of diamond thin films. To this end, we are currently investigating the use of Ni single crystals on which different types of epitaxial metals are grown by molecular beam epitaxy (MBE) for lattice matching to diamond as well as surface chemistry modification. This contribution reports briefly on our microscopic observations that are integral to these endeavors.

Potentiation of bromotrichloromethane hepatotoxicity in male rats exposed to 10 ppm dietary chlordecone: Electron Microscopic and biochemical study

1990 ◽  
Vol 48 (3) ◽  
pp. 284-285
Author(s):  
O. M. Faroon ◽  
R. W. Henry ◽  
M. G. Soni ◽  
H. M. Mehendale
Keyword(s):  
Free Radical ◽  
Biochemical Study ◽  
Prior Exposure ◽  
Male Rats ◽  
Cellular Injury ◽  
Low Doses ◽  
Mixed Function Oxidase ◽  
Electron Microscopic ◽  
Potent Inducer ◽  
Cellular Energy

Previous work has shown that mirex undergoes photolytic dechlorination to chlordecone (CD) (KeponeR) in the environment. Much work has shown that prior exposure to nontoxic levels of CD causes potentiation of hepatotoxicity and lethality of CCl4, BrCCl3 and other halomethane compounds. Potentiation of bromotrichloromethane hepatotoxicity has been associated with compounds that stimulate the activity of hepatic mixed-function oxidase (MFO). An increase in the metabolism of halomethane by the MFO to a free radical initiates peroxidative decomposition of membranal lipids ending in massive cellular injury. However, not all MFO inducers potentiate BrCCl3 hepatotoxicity. Potentiation by much larger doses of phenobarbital is minimal and th at by a more potent inducer of MFO, mirex, is negligible at low doses. We suggest that the CD and bromotrichloromethane interaction results in a depletion of cellular energy and thereby reducing the cellular ability to undergo mitosis.

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