scholarly journals Appendix: Electron microscopy of islets Of langerhans in rabbit pancreas slices incubated in vitro

1967 ◽  
Vol 102 (3) ◽  
pp. 928-1928 ◽  
Author(s):  
J. R. Williamson ◽  
P.E. Lacy ◽  
K. W. Taylor
Keyword(s):  
Electron Microscopy ◽  
Islets Of Langerhans ◽  
Rabbit Pancreas

scholarly journals Potassium ions and the secretion of insulin by islets of Langerhans incubated in vitro

1968 ◽  
Vol 108 (1) ◽  
pp. 17-24 ◽  
Author(s):  
S. L. Howell ◽  
K W Taylor
Keyword(s):  
Insulin Secretion ◽  
Insulin Release ◽  
Islets Of Langerhans ◽  
Potassium Ions ◽  
Collagenase Digestion ◽  
Islet Tissue ◽  
Rabbit Pancreas ◽  
K Concentration

1. A method was devised for the isolation of islets of Langerhans from rabbit pancreas by collagenase digestion in order to study the influx and efflux of K+ in islets during insulin secretion. 2. Glucose-induced insulin release was accompanied by an increased rate of uptake of 42K+ by the islets of Langerhans, though this was not the case for secretion in response to tolbutamide. Ouabain significantly inhibited the uptake of 42K+ by islet tissue. 3. No significant increase in the rate of efflux of 42K+ was demonstrated during active insulin secretion. 4. Slices of rabbit pancreas were incubated in media of different K+ content, and rates of insulin release were determined. Alteration of the K+ concentration of the medium between 3 and 8mm had no effect on the rate of insulin release by pancreas slices. However, decrease of the K+ concentration to 1mm resulted in inhibition of secretion in response to both glucose and to tolbutamide. Conversely, an increase in K+ concentration increased rates of insulin release in response to both these stimuli. 5. It is concluded that, though unphysiological concentrations of K+ may influence the secretion of insulin, fluxes of K+ in the islets do not appear to be important in the initiation of insulin secretion.

Sem Studies of Co-Cr-Mo Surgical Implant Alloy Corrosion Behavior

1982 ◽  
Vol 40 ◽  
pp. 520-521
Author(s):  
Ann Chidester Van Orden ◽  
John L. Chidester ◽  
Anna C. Fraker ◽  
Pei Sung
Keyword(s):  
Electron Microscopy ◽  
Corrosion Behavior ◽  
Anodic Polarization ◽  
Saline Solution ◽  
Saturated Calomel Electrode ◽  
Physiological Saline ◽  
X Ray ◽  
Physiological Saline Solution ◽  
Scanning Electron

The influence of small variations in the composition on the corrosion behavior of Co-Cr-Mo alloys has been studied using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and electrochemical measurements. SEM and EDX data were correlated with data from in vitro corrosion measurements involving repassivation and also potentiostatic anodic polarization measurements. Specimens studied included the four alloys shown in Table 1. Corrosion tests were conducted in Hanks' physiological saline solution which has a pH of 7.4 and was held at a temperature of 37°C. Specimens were mechanically polished to a surface finish with 0.05 µm A1203, then exposed to the solution and anodically polarized at a rate of 0.006 v/min. All voltages were measured vs. the saturated calomel electrode (s.c.e.).. Specimens had breakdown potentials near 0.47V vs. s.c.e.

Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

1977 ◽  
Vol 35 ◽  
pp. 460-461
Author(s):  
Tai-Te Chao ◽  
John Sullivan ◽  
Awtar Krishan
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Transmission Electron Microscopy ◽  
Tubulin Polymerization ◽  
Vinca Alkaloids ◽  
Antimitotic Activity ◽  
Transmission Electron ◽  
Flow Microfluorometry ◽  
Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

Some Structural Features of Metaphase Chromosomes of Mice and Men

1967 ◽  
Vol 25 ◽  
pp. 190-191
Author(s):  
Godfrey C. Hoskins ◽  
Betty B. Hoskins
Keyword(s):  
Electron Microscopy ◽  
Electron Micrographs ◽  
Structural Features ◽  
Metaphase Chromosomes ◽  
The Future ◽  
Of Mice And Men ◽  
Mouse Cells ◽  
Human And Mouse

Metaphase chromosomes from human and mouse cells in vitro are isolated by micrurgy, fixed, and placed on grids for electron microscopy. Interpretations of electron micrographs by current methods indicate the following structural features.Chromosomal spindle fibrils about 200Å thick form fascicles about 600Å thick, wrapped by dense spiraling fibrils (DSF) less than 100Å thick as they near the kinomere. Such a fascicle joins the future daughter kinomere of each metaphase chromatid with those of adjacent non-homologous chromatids to either side. Thus, four fascicles (SF, 1-4) attach to each metaphase kinomere (K). It is thought that fascicles extend from the kinomere poleward, fray out to let chromosomal fibrils act as traction fibrils against polar fibrils, then regroup to join the adjacent kinomere.

Electron Microscopy of Fibroblasts from Myotonic Muscular Dystrophy Patients

1981 ◽  
Vol 39 ◽  
pp. 498-499
Author(s):  
S. E. Miller ◽  
G. B. Hartwig ◽  
R. A. Nielsen ◽  
A. P. Frost ◽  
A. D. Roses
Keyword(s):  
Electron Microscopy ◽  
Muscular Dystrophy ◽  
Genetic Diseases ◽  
Skin Fibroblasts ◽  
Inborn Errors ◽  
Cytoplasmic Inclusions ◽  
Cultured Skin ◽  
Myotonic Muscular Dystrophy ◽  
Glycosaminoglycan Metabolism

Many genetic diseases can be demonstrated in skin cells cultured in vitro from patients with inborn errors of metabolism. Since myotonic muscular dystrophy (MMD) affects many organs other than muscle, it seems likely that this defect also might be expressed in fibroblasts. Detection of an alteration in cultured skin fibroblasts from patients would provide a valuable tool in the study of the disease as it would present a readily accessible and controllable system for examination. Furthermore, fibroblast expression would allow diagnosis of fetal and presumptomatic cases. An unusual staining pattern of MMD cultured skin fibroblasts as seen by light microscopy, namely, an increase in alcianophilia and metachromasia, has been reported; both these techniques suggest an altered glycosaminoglycan metabolism An altered growth pattern has also been described. One reference on cultured skin fibroblasts from a different dystrophy (Duchenne Muscular Dystrophy) reports increased cytoplasmic inclusions seen by electron microscopy. Also, ultrastructural alterations have been reported in muscle and thalamus biopsies from MMD patients, but no electron microscopical data is available on MMD cultured skin fibroblasts.

Alterations of ultrastructure and elemental composition in cultured human epidermal keratinocytes after treatment with nitrofurazone and silver sulfadiazine

1987 ◽  
Vol 45 ◽  
pp. 676-677
Author(s):  
A. R. Crooker ◽  
M. C. Myers ◽  
T. L. Beard ◽  
E. S. Graham
Keyword(s):  
Electron Microscopy ◽  
Elemental Composition ◽  
Pyrolytic Carbon ◽  
Human Keratinocytes ◽  
Silver Sulfadiazine ◽  
Epidermal Keratinocytes ◽  
Human Epidermal Keratinocytes ◽  
Culture Systems ◽  
Cytotoxicity Endpoints

Cell culture systems have become increasingly popular as a means of screening toxic agents and studying toxic mechanisms of drugs and other chemicals at the cellular and subcellular levels. These in vitro tests can be conducted rapidly in a broad range of relevant mammalian culture systems; a variety of biological and biochemical cytotoxicity endpoints can be examined. The following study utilized human keratinocytes to evaluate the relative cytotoxicities of nitrofurazone (NF) and silver sulfadiazine (SS), the active ingredients of FURACIN(R) Topical Cream and SILVADENE(R) Cream, respectively. These compounds are anti-infectives used in the treatment of burn patients. Cell ultrastructure and elemental composition were utilized as cytotoxicity endpoints.Normal Human Epidermal Keratinocytes (HK) were prepared from the EpiPackTM culture system (Clonetics Corporation, Boulder, CO). For scanning electron microscopy (SEM) and transmission electron microscopy (TEM), cells were seeded on sterile 35 mm Falcon plastic dishes; for elemental microanalysis, cells were plated on polished pyrolytic carbon discs (E. Fullam, Latham, NY) placed in the culture dishes.

Correlation Between Cellular Functions and Morphological Changes of Human Trophoblast in Vitro

1975 ◽  
Vol 33 ◽  
pp. 600-601
Author(s):  
John C. Garancis ◽  
Robert O. Hussa ◽  
Michael T. Story ◽  
Donald Yorde ◽  
Roland A. Pattillo
Keyword(s):  
Electron Microscopy ◽  
Cellular Proliferation ◽  
Morphological Changes ◽  
Culture Fluid ◽  
Cellular Functions ◽  
Human Trophoblast ◽  
Transmission Electron ◽  
Marked Activity ◽  
Malignant Trophoblast

Human malignant trophoblast cells in continuous culture were incubated for 3 days in medium containing 1 mM N6-O2'-dibutyryl cyclic adenosine 3':5'-monophosphate (dibutyryl cyclic AMP) and 1 mM theophylline. The culture fluid was replenished daily. Stimulated cultures secreted many times more chorionic gonadotropin and estrogens than did control cultures in the absence of increased cellular proliferation. Scanning electron microscopy revealed remarkable surface changes of stimulated cells. Control cells (not stimulated) were smooth or provided with varying numbers of microvilli (Fig. 1). The latter, usually, were short and thin. The surface features of stimulated cells were considerably different. There was marked increase of microvilli which appeared elongated and thick. Many cells were covered with confluent polypoid projections (Fig. 2). Transmission electron microscopy demonstrated marked activity of cytoplasmic organelles. Mitochondria were increased in number and size; some giant forms with numerous cristae were observed.

Scanning Electron Microscopy of Staphylococcus Epidermidis Adherence to Continuous Ambulatory Peritoneal Dialysis Catheters

1985 ◽  
Vol 43 ◽  
pp. 520-521
Author(s):  
William J. Lamoreaux ◽  
David L. Smalley ◽  
Larry M. Baddour ◽  
Alfred P. Kraus
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Peritoneal Dialysis ◽  
Continuous Ambulatory Peritoneal Dialysis ◽  
Staphylococcus Epidermidis ◽  
Sterile Saline ◽  
Intravascular Devices ◽  
Capd Patient ◽  
Scanning Electron

Infections associated with the use of intravascular devices have been documented and have been reported to be related to duration of catheter usage. Recently, Eaton et al. reported that Staphylococcus epidermidis may attach to silastic catheters used in continuous ambulatory peritoneal dialysis (CAPD) treatment. The following study presents findings using scanning electron microscopy (SEM) of S. epidermidis adherence to silastic catheters in an in vitro model. In addition, sections of polyvinyl chloride (PVC) dialysis bags were also evaluated by SEM.The S. epidermidis strain RP62A which had been obtained in a previous outbreak of coagulase-negative staphylococcal sepsis at local hospitals was used in these experiments. The strain produced surface slime on exposure to glucose, whereas a nonadherent variant RP62A-NA, which was also used in these studies, failed to produce slime. Strains were grown overnight on blood agar plates at 37°C, harvested from the surface and resuspended in sterile saline (0.85%), centrifuged (3,000 rpm for 10 minutes) and then washed twice in 0.1 M phosphate-buffered saline at pH 7.0. Organisms were resuspended at a concentration of ca. 106 CFU/ml in: a) sterile unused dianeal at 4.25% dextrose, b) sterile unused dianeal at 1.5% dextrose, c) sterile used dialysate previously containing 4.25% dextrose taken from a CAPD patient, and d) sterile used dialysate previously containing 1.5% dextrose taken from a CAPD patient.

Time-Resolved Cryo-Electron Microscopy of Oscillating Microtubules

1990 ◽  
Vol 48 (1) ◽  
pp. 502-503
Author(s):  
Eva-Maria Mandelkow ◽  
Ron Milligan
Keyword(s):  
Electron Microscopy ◽  
Dynamic Instability ◽  
Entire Solution ◽  
Reaction Scheme ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
A Chain ◽  
Ray Scattering

Microtubules form part of the cytoskeleton of eukaryotic cells. They are hollow libers of about 25 nm diameter made up of 13 protofilaments, each of which consists of a chain of heterodimers of α-and β-tubulin. Microtubules can be assembled in vitro at 37°C in the presence of GTP which is hydrolyzed during the reaction, and they are disassembled at 4°C. In contrast to most other polymers microtubules show the behavior of “dynamic instability”, i.e. they can switch between phases of growth and phases of shrinkage, even at an overall steady state [1]. In certain conditions an entire solution can be synchronized, leading to autonomous oscillations in the degree of assembly which can be observed by X-ray scattering (Fig. 1), light scattering, or electron microscopy [2-5]. In addition such solutions are capable of generating spontaneous spatial patterns [6].In an earlier study we have analyzed the structure of microtubules and their cold-induced disassembly by cryo-EM [7]. One result was that disassembly takes place by loss of protofilament fragments (tubulin oligomers) which fray apart at the microtubule ends. We also looked at microtubule oscillations by time-resolved X-ray scattering and proposed a reaction scheme [4] which involves a cyclic interconversion of tubulin, microtubules, and oligomers (Fig. 2). The present study was undertaken to answer two questions: (a) What is the nature of the oscillations as seen by time-resolved cryo-EM? (b) Do microtubules disassemble by fraying protofilament fragments during oscillations at 37°C?

Application of Spurr, LX112, LX112/ARALDITE 502, POLY/BED 812 and Effapoxy Embedding Media to in Vitro Agar-Cultured Bone Marrow Colonies.

1980 ◽  
Vol 38 ◽  
pp. 646-647
Author(s):  
Glenn M. Buchanan ◽  
Dennis A. Stewart
Keyword(s):  
Electron Microscopy ◽  
Bone Marrow ◽  
Cell Cell

In vitro bone-marrow derived colonies cultured in agar and prepared in Epon 812 for electron microscopy occassionally produce blocks that are too soft for sectioning. We attribute this softness to the retention, after standard dehydration, of water by the agar and to the relatively slow penetration of the agar by Epon-based embedding media. The agar cannot be removed or replaced since this would disrupt the colony integrity and prevent the study of cell-cell relationships. This paper describes the procedures and results of more extensive specimen dehydration and of embedding with Epon-replacement formulations.

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