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At least 523 records · Page 29Linked to original sources

PubMed1960

Multinucleation of skeletal muscle in vitro.

Healthy, mature, spontaneously contracting muscle was cultivated from explants of 13-day chick embryos for periods up to 4 months in the multipurpose chamber (Rose, 1954) using cellophane-strip technique (Rose et al., 1958) with silicone gaskets, Eagle's medium including 10 per cent horse serum reinforced with 300 mg-per cent of glucose, and the teased type of explant. This method provided optically ideal conditions for the study of muscle fibers with oil immersion, phase contrast time-lapse cinematography at 1 frame per minute without apparent damage for periods as long as 10 days. In no case was mitosis, amitosis, or nuclear "budding" observed in the course of muscle development. Multinuclear muscle fibers have been shown with cine technique to result from both myoblast fusion and polar extension of preformed (explanted) muscle tissue. Myoblast fusion was the only demonstrable way of giving rise to multinucleation. Nuclear membrane "wrinkling" was shown to be merely a temporary distortion that occurred during nuclear migration and rotation. It is suggested that this phenomenon may be responsible for numerous reports of amitosis in the genesis of muscle fibers. The histological development of new straps resulted from an orderly sequence of events. Included in these were polar extension, nuclear migration, rotation, and fixation. Following these events there was increased mitochondrial activity, myofibril formation, and cross-banding. Spontaneous contractions were seen throughout the entire course of differentiation in vitro but became more regular and stronger in the later stages.

Animals↗

PubMed1960

Observations on the chromatinic bodies of Streptomyces coelicolor.

Colonies of Streptomyces coelicolor growing on cellophane and impression preparations from sporing colonies were stained for chromatin by the methods of Feulgen, DeLamater (1951), and Piéchaud (1954). The chromatinic bodies of the substrate hyphae have a great variety of configurations. During the development of the spores, elongated chromatinic structures in the young aerial hyphae separate into a number of subunits and a single round chromatinic body is included in each spore.

Chromatin↗

PubMed1961

The Golgi complex in living osteoblasts.

Embryo chick leg bones were cultivated under sheets of dialysis cellophane in multipurpose culture chambers. The osteoblasts emigrating in this environment contained phase gray juxtanuclear bodies from which phase white droplets emanated. These were concluded to be the Golgi complex and are described with respect to their living morphology, microscopically observed functional activity, vital staining, and cytochemical reactions.

Bone and Bones↗

PubMed1969

Lasting biological effects of early environmental influences. IV. Notes on the physicochemical and immunological characteristics of an enterovirus that depresses the growth of mice.

Physicochemical and immunological techniques have been used in an attempt to characterize a filterable agent, separated from the intestines of mice raised under ordinary conditions of husbandry, which produces a lasting depression of weight in specific pathogen-free (SPF) mice when administered to them orally shortly after birth. Although this agent has not yet been identified, it will be tentatively designated here as enterovirus. The mouse enterovirus can be readily sedimented by ultracentrifugation and by precipitation at pH 4.3; it does not pass through cellophane membranes. Its infective power is completely destroyed by ultraviolet radiation, but is resistant to heating at 56 degrees C, exposure to ether, treatment with trypsin, ribonuclease, and deoxyribonuclease. Dialysis and treatment with ether and nucleases greatly increase the infective activity of the intestinal filtrates containing the enterovirus, a finding which suggests that these procedures eliminate or destroy some inhibitory substance(s). The mouse enterovirus causes hemagglutination of mouse red blood cells. When injected into rabbits, it elicits in them an immune response that renders their serum capable of neutralizing its weight-depressing activity. As measured by inhibition of hemagglutination or complement fixation, the sera of infected mice do not exhibit any significant activity against usual mouse viruses. Centrifugation of the mouse enterovirus in 50%-20% sucrose gradient gave almost complete recovery of the infectivity and of hemagglutinating activity in the same fraction. In contrast, the protein content of the material was distributed through the various fractions. Consequently, this procedure resulted in a marked increase of specific activity.

Animals↗

PubMed1982

Depletion of epidermal langerhans cells and Ia immunogenicity from tape-stripped mouse skin.

To explore the relationships among Ia antigen expression, epidermal Langerhans cells, and the immunogenicity of skin allografts, cellophane tape-stripping was used in H-2 congenic and recombinant mice of defined immunogenetic disparity. Tape-stripping of murine abdominal wall skin achieved almost complete depletion of epidermal Langerhans cells within a few hours of application, as measured by cell surface ATPase and expression of Ia antigens. Tape-stripping also reduced, to a considerable degree (but not absolutely), the Ia immunogenicity of skin allografts prepared from stripped surfaces. No comparable reduction in immunogenicity of class I major histocompatibility determinants was observed, suggesting that Langerhans cells are relatively unimportant in the presentation of H-2K antigens in skin grafts. Langerhans cells reappear within 24 h of tape-stripping to anatomically intact skin, but are detectable in orthotopically grafted only after the graft has been in residence for 4 d, i.e., shortly after it has acquired a blood supply. Repopulating Langerhans cells at that time and thereafter are exclusively of host origin. These results indicate that the traffic of Langerhans cells to the skin can be extremely dynamic, especially when the epidermal surface has been markedly disturbed, and the data imply that, under normal circumstances, large numbers of Langerhans cells can be mobilized readily from an available pool of precursors.

Abdominal Muscles↗

PubMed1952

The intrarenal pressure during experimental renal hypertension.

The intrarenal interstitial pressure was measured during the course of experimental renal hypertension in dogs. In perinephritic hypertension, produced by wrapping the kidney in a cellophane bag, the intrarenal pressure rose slowly from the normal value of 25 mm. Hg to a final level of about 60 mm. Hg. Strong pressure pulsations were observed in the renal parenchyma during this type of hypertension. In the hypertension following partial occlusion of the renal artery, the intrarenal pressure remained approximately normal, except in malignant hypertension when it tended to decline to about 9 mm. Hg. The hypertension of perinephritis is interpreted as a consequence of renal ischemia, the high intrarenal pressure, produced by the constricting fibrotic hull, acting to reduce the effective perfusion pressure of the kidney. The two experimental hypertensions herein examined are considered as examples of influent resistance hypertensions and effluent resistance hypertensions, the former being due to renal arterial or arteriolar resistance and the latter due to renal venous resistance, specifically at the arcuate-interlobar junction. The application of this concept to renal hypertensive disease in man is discussed.

Animals↗

PubMed1950

Crystalline desoxyribonuclease; digestion of thymus nucleic acid; the kinetics of the reaction.

A study was made of the enzymatic properties of crystalline desoxyribonuclease. The general effect of the crystalline enzyme on its specific substrate, thymus nucleic acid, was found to be essentially the same as described by previous workers for the digestive action of crude preparations of the enzyme. The digestive action consists mainly in splitting thymus nucleic acid into fragments approaching the size of tetranucleotides. The digested nucleic acid is diffusible through collodion or cellophane membranes and is non-precipitable with strong acid, alcohol, or proteins. The digestion of thymus nucleic acid by desoxyribonuclease is accompanied by the liberation of one atom equivalent of free acid per four atoms of nucleic acid phosphorus. Crystalline desoxyribonuclease acts very slowly, if at all, in the absence of magnesium (or manganese) ions. The optimal concentration of magnesium ion required increases with the increase in concentration of the substrate but is independent of the enzyme concentration. The optimal pH range for the action of crystalline desoxyribonuclease is 6.0 to 7.0. A study was made of the kinetics of the digestion of thymus nucleic acid as manifested mainly by the gradual formation of acid-soluble split products. At low concentrations of nucleic acid, the process approximates closely a reaction of the first order, the unimolecular constant being independent of the concentration of desoxyribonuclease in the digestion mixture. At relatively higher concentrations of substrate, however, the initial rate of reaction decreases rapidly with the increase in concentration of substrate, and the reaction as a whole is represented by non-symmetric S-shaped curves apparently too complicated for a simple rational interpretation.

Deoxyribonucleases↗

PubMed1951

Galvanotaxis of slime mold.

The plasmodium of Physarum polycephalum reacts to direct current by migration toward the cathode. Cathodal migration was obtained upon a variety of substrata such as baked clay, paper, cellophane, and agar with a current density in the substratum of 1.0 microa./mm.(2) Injury was produced by current densities of 8.0 to 12.0 microa./mm.(2) The negative galvanotactic response was not due to electrode products. Attempts to demonstrate that the response was due to gradients or orientation in the substratum, pH changes in the mold, cataphoresis, electroosmosis, or endosmosis were not successful. The addition of salts (CaCl(2), LiCl, NaCl, Na(2)SO(4), NaHCO(3), KCl, MgSO(4), sodium citrate, and sea water) to agar indicated that change of cations had more effect than anions upon galvanotaxis and that the effect was upon threshold values. K ion (0.01 M KCl) increased the lower threshold value to 8.0 microa./mm.(2) and the upper threshold value to 32.0 microa./mm.(2), whereas the Li ion (0.01 M LiCl) increased the lower threshold to only 4.0 microa./mm.(2) and the upper threshold to only 16.0 microa./mm.(2) The passage of electric current produced no increase in the rate of cathodal migration; neither was there a decrease until injurious current densities were reached. With increase of subthreshold current densities there was a progressive decrease in rate of migration toward the anode until complete anodal inhibition occurred. There was orientation at right angles to the electrodes in alternating current (60 cycle) with current density of 4.0 microa./mm.(2) and in direct current of 5.0 microa./mm.(2) when polarity of current was reversed every minute. It is concluded that the negative galvanotactic response of P. polycephalum is due to inhibition of migration on the anodal side of the plasmodium and that this inhibition results in the limitation of the normal migration of the mold to a cathodal direction. The mechanism of the anodal inhibition has not been elucidated.

Fungi↗

PubMed1971

Hemoglobin charge dependence on hemoglobin concentration in vitro.

Studies have been made of the dependence of the charge of the hemoglobin molecule on hemoglobin concentration in the concentration range between 3 and 11 mmolal. The charge has been determined by measuring the distribution of (42)K between a hemoglobin solution in a cellophane bag and an external solution. The pH was 6.6, the K concentration was 10 mM, and the temperature was 4 degrees C. The charge decreased along a sigmoid curve from a value of +3 in the most dilute solutions to a value of +0.5 in the most concentrated solutions. The results were in excellent agreement with earlier studies of Gary-Bobo and Solomon in which Cl distribution was measured between human red cells and external solutions and thus give added support to the conclusion that the apparent anomalous osmotic behavior of human red cells may be attributed to concentration-dependent changes in the hemoglobin net charge. The present findings also support the view that the water in the red cell is solvent water for K and Cl and differs in no quantitatively important respect from bulk water in free solution.

Journal Article↗

PubMed1971

The effect of valinomycin on the electrical properties of solutions of red cell lipids in n-decane.

This paper reports the electrical properties of thick lipid membranes in the absence and presence of valinomycin. The thick lipid membranes were formed by placing a solution of sheep red cell lipids in decane between two cellophane partitions which formed the interfaces between the membrane and the two aqueous bathing solutions. The DC electrical resistance of these structures was found to be directly proportional to the reciprocal of the concentration of lipids in the decane (C(L)). The limiting resistance, as (C(L) (-1)) approached zero, was 3 x 10(8) ohm-cm(2). Resistance was also found to be linearly related to membrane thickness. The limiting resistance at zero thickness was again 1-3 x 10(8) ohm-cm(2). These data are interpreted to indicate that the DC resistance of thick lipid membranes comprises two surface resistances (R(S)) at each interface with the aqueous bathing solutions, and a bulk resistance (R(B)) of the lipid-decane solution, arranged in series. Measurements of the effect of variations of area on resistance were consistent with this interpretation. Valinomycin reduced R(S) but had no effect on R(B). Under certain conditions, thick lipid membranes containing valinomycin behaved like highly selective K(+) electrodes.

Animals↗

PubMed2004

Comparison of liposome-encapsulated acyclovir with acyclovir ointment: ocular pharmacokinetics in rabbits.

A positively charged liposomal formulation for topical administration of acyclovir (ACV) was investigated in comparison with a commercial ACV ointment, by determining the pharmacokinetic profile of the drug in the aqueous humor of rabbits after topical administration. The ointment was tested at two different strengths: undiluted (3.0%) and diluted to the same ACV concentration as the liposomal vehicle (0.12%). A liquid formulation containing ACV plus "empty" liposomes and an isotonic aqueous ACV solution were also tested. The applied ACV dose was 0.18 mg, except for the full-strength (3.0%) ointment, in which case it was 1.5 mg. The ACV liposomal dispersion (LIPO-ACV) produced a significantly higher drug concentration profile in the aqueous with respect the three reference formulations containing the same ACV concentration, and showed a 90-minute plateau. The aqueous humor ACV concentration maintained by LIPO-ACV during the plateau was in the upper range of the ID(50)s (0.01 to 0.7 microg/mL) reported for Herpes simplex type 1. In spite of the much higher dose (1.5 versus 0.18 mg), the area under curve (AUC) produced by the full-strength 3.0% ointment was only 1.6 times greater than that corresponding to the liposomal vehicle. In vitro release tests through a cellophane membrane substantiated the concept that positively charged liposomal formulations owe their efficacy to interactions with the positively charged corneal epithelium.

Acyclovir↗

PubMed1996

The G alpha i homologue gna-1 controls multiple differentiation pathways in Neurospora crassa.

Heterotrimeric G proteins are components of principal signaling pathways in eukaryotes. In higher organisms, alpha subunits of G proteins have been divided into four families, Gi, Gs, Gq, and G12. We previously identified a G alpha i homologue gna-1 in the filamentous fungus Neurospora crassa. Now we report that deletion of gna-1 leads to multiple phenotypes during the vegetative and sexual cycles in N. crassa. On solid medium, delta gna-1 strains have a slower rate of hyphal apical extension than wild type, a rate that is more pronounced under hyperosmotic conditions or in the presence of a cellophane overlay. delta gna-1 mutants accumulate less mass than wild-type strains, and their mass accumulation is not affected in the same way by exposure to light. delta gna-1 strains are defective in macroconidiation, possessing aerial hyphae that are shorter, contain abnormal swellings, and differentiate adherent macroconidia. During the sexual cycle, delta gna-1 strains are fertile as males. However, the mutants are female-sterile, producing small, aberrant female reproductive structures. After fertilization, delta gna-1 female structures do not enlarge and develop normally, and no sexual spores are produced. Thus, mutation of gna-1 results in sex-specific loss of fertility.

Base Sequence↗

PubMed2004

Physiology of the endothelium.

In the past, the endothelium was considered to be inert, described as a 'layer of nucleated cellophane', with only non-reactive barrier properties, such as presentation of a non-thrombogenic surface for blood flow and guarding against pro-inflammatory insults. However, it is now becoming clear that endothelial cells actively and reactively participate in haemostasis and immune and inflammatory reactions. They regulate vascular tone via production of nitric oxide, endothelin and prostaglandins and are involved in the manifestations of atherogenesis, autoimmune diseases and infectious processes. They produce and react to various cytokines and adhesion molecules and it is now clear that they can mount anti- and pro-inflammatory and protective responses depending on environmental conditions and are key immunoreactive cells. Endothelial dysfunction or activation also contributes to a variety of disease states.

Arteriosclerosis↗

PubMed1977

Standardization of a preparative ultracentrifuge method for quantitative determination or protein binding of seven antibiotics.

A preparative ultracentrifuge method was standardized for determination of quantitative binding of cephalothin, cefamandole, cefazolin, cefaclor, erythromycin, gentamicin, and chloramphenicol to human serum proteins. At achievable in vivo concentrations, serum binding was 78.5% for cephalothin, 79.9% for cefamandole, 88.5% for cefazolin, 23.5% for cefaclor, 41.9% for erythromycin, 22.7% for gentamicin, and 59.5% for chloramphenicol. Techniques that use semipermeable cellophane or diaflow membranes, cross-linked dextran, inhibition of bacterial growth, protein precipitation, or liquid partitioning all have inherent problems with either the ligand or the antibiotic adversely interacting with the experimental apparatus. Ultracentrifugation provides a rapid, reproducible technique for protein-binding determinations of the classes of antibiotics described.

Anti-Bacterial Agents↗

PubMed1989

Exploration of the microbial anatomy of normal human skin by using plasmid profiles of coagulase-negative staphylococci: search for the reservoir of resident skin flora.

The aerobic bacterial flora of the top 25 layers of the stratum corneum of normal human skin was characterized by sampling glabrous skin with contact plates and analyzing plasmid patterns of coagulase-negative staphylococci (SCN) by agarose gel electrophoresis. The number of colonies of SCN on the skin surface at 12 sites varied from 14 to 838. Removal of five keratinized layers by sequential stripping with cellophane tape reduced the number of colonies by 80% (median; range, 42%-91%). Counts remained constant during removal of 20 additional layers. SCN with six different plasmid patterns were identified at a site on the skin surface. After removal of 25 layers, colonies with a single pattern were clustered in one quadrant of the site. The site was sterilized and covered with a sterile dressing for 18 h. Colonies reappeared in the same quadrant of the site; six of seven had the same pattern seen 18 h previously. Observations at three other sites were similar. Reappearance of the same strain(s) of SCN following sterilization of the site suggests that the reservoir for normal resident skin flora is located below the stratum corneum, perhaps in hair follicles and ducts of sebaceous glands.

DNA, Bacterial↗

PubMedDate not supplied

Suicidal inhalation of motorbike exhaust: adding new data to the literature about the contribution of gasoline in the cause of death.

We would like to alert toxicologists to the importance of testing for gasoline, and for volatile hydrocarbons in general, in deaths involving inhalation of exhaust fumes occurring in closed spaces with running motors or machinery. We present here a case of suicidal inhalation of motorbike exhaust, a mixture of carbon monoxide (CO) and gasoline vapor, by a 38-year-old female. She was found in her closed home garage with a hose extending from the exhaust pipe of a motorbike through a cellophane plastic device into a closed tent in which the victim lay. She left two suicide notes nearby. The carboxyhemoglobin (COHb) was measured using visible spectrophotometry. The toxicological screening and quantitation of gasoline was performed by means of gas chromatography with flame-ionization detector and confirmation was performed using gas chromatography-mass spectrometry. The %COHb determined in blood was 73%. Gasoline concentrations in heart blood and vitreous humor were 22.3 and 1.0 mg/L, respectively. Although fatalities with CO at this rate are common, we would like to highlight the role of gasoline and add new quantitative data of this toxic substance to the scarce literature. Based upon the toxicological data, along with the information provided by the medical examiner, the cause of death was determined to be CO and gasoline poisoning and the manner of death suicide.

Adult↗

PubMed1983

Flexibility in RNA priming of Okazaki pieces at the E. coli replication fork.

We present results which suggest considerable flexibility in the RNA priming of Okazaki pieces at the E. coli replication fork. Using film lysates on cellophane discs, we have identified RNA at the 5' ends of Okazaki pieces. All four ribonucleotides are found to be present at the RNA-DNA junction if all four ribonucleoside triphosphates are used. However, if only ATP, or ATP and GTP are used, then only 2' (3')AMP, or 2' (3')AMP and 2' (3')GMP are found at the RNA-DNA junction. A nearest neighbor analysis of RNA associated with Okazaki pieces using alpha 32P-CTP as a probe shows a similar dependence of nearest neighbor composition on the ribonucleoside triphosphate composition of the incubation mixture. Thus, the nucleotide composition of the RNA primers at the ends of Okazaki pieces varies as a function of the ribonucleoside triphosphates available.

DNA↗

PubMed1978

A cell-free system for the replication fo bacteriophage M-13 duplex DNA.

Cell-free extracts from M-13 am5 infected Escherichia coli cells which are highly concentrated on cellophane membrane disks replicate efficiently endogenous M-13 duplex DNA. If the reaction is carried out in the presence of bromodeoxyuridine triphosphate, the majority of the label is found in two classes of hybrid DNA molecules in which either the viral or the complementary strand is newly synthesized. A minor portion of the label is incorporated into fully synthetic duplex DNA. DNA synthesis requires ATP and is inhibited by nalidixic acid, novobiocin, and arabinosylnucleoside triphosphates. Rifampicin blocks preferentially the synthesis of molecules with labeled complementary strands. A similar effect is observed upon addition of the helix-destabilising M-13 gene V protein. In contrast, addition of E. coli helix-destabilising protein (Eco HD-protein) stimulates the synthesis of both types of hybrid DNA molecules as well as the formation of fully synthetic duplex DNA.

Coliphages↗