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At least 433 records · Page 24Linked to original sources

PubMed2006

Zinc phosphate transformations by the Paxillus involutus/pine ectomycorrhizal association.

In this research, we investigate zinc phosphate transformations by Paxillus involutus/pine ectomycorrhizas using zinc-resistant and zinc-sensitive strains of the ectomycorrhizal fungus under high- and low-phosphorus conditions to further understand fungal roles in the transformation of toxic metal minerals in the mycorrhizosphere. Mesocosm experiments with ectomycorrhizas were performed under sterile conditions with zinc phosphate localized in cellophane bags: zinc and phosphorus mobilization and uptake by the ectomycorrhizal biomass were analyzed. In the presence of a phosphorus source, an ectomycorrhizal association with a zinc-resistant strain accumulated the least zinc compared to a zinc-sensitive ectomycorrhizal association and non-mycorrhizal plants. Under low-phosphorus conditions, mycorrhizal seedlings infected with the zinc-resistant strain increased the dissolution of zinc phosphate and zinc accumulation by the plant. Extended X-ray absorption fine structure analysis of both mycorrhizal and nonmycorrhizal roots showed octahedral coordination of zinc by oxygen-containing ligands such as carboxylates or phosphate. We conclude that zinc phosphate solubilization and zinc and phosphorus uptake by the association depend on ectomycorrhizal infection, strain of the mycobiont, and the phosphorus status of the matrix.

Basidiomycota↗

PubMed1998

The morphologic changes in lamellar bodies and intercorneocyte lipids after tape stripping and occlusion with a water vapor-impermeable membrane.

It has been reported that artificial restoration of barrier function by a water vapor-impermeable membrane after tape stripping induces barrier abrogation in hairless mice, impeding rather than enhancing barrier recovery. To address this issue, we examined the morphologic changes in the epidermis after tape stripping and occlusion with a water vapor-impermeable membrane in murine skin. Male hairless mice were used for all studies of barrier perturbation and occlusion. Barrier disruption was achieved by repeated application of cellophane tape. Immediately after tape stripping the animals were wrapped in a tightly fitting water vapor-impermeable membrane. Transepidermal water loss (TEWL) was measured 20 min after tape stripping and 14, 24, 36, 48 and 60 h after occlusion. For electron microscopy the samples were treated with osmium tetroxide (OsO4) or ruthenium tetroxide (RuO4). When tape-stripped animals were wrapped in a water vapor-impermeable membrane, thereby preventing water flux, barrier function did not recover normally. These results demonstrate that an artificial block to TEWL with an impermeable membrane did not enhance barrier recovery. By electron microscopy many transitional cells and lacunae of various sizes were seen within the intercellular spaces of the stratum corneum after occlusion following tape stripping. Occlusion also caused alterations in both lipid lamellar membrane structures in the stratum corneum interstices and the lamellar bodies in the cytosol of granulocytes and transitional cells. Secreted lamellar body contents also appeared to be abnormal in the stratum corneum-stratum granulosum junction.

Animals↗

PubMed2004

Hyperconvolution of the inner limiting membrane in vitreomaculopathies.

BACKGROUND: This study investigates the similarities and differences between epiretinal membranes in four clinically distinct types of vitreomaculopathy. We propose a hypothesis on the origin of the predominant cell type and its potential role in causing these conditions. METHODS: Epiretinal membranes (ERMs) surgically removed from a prospective, consecutive series of vitrectomies for macular pucker associated with an untreated peripheral horseshoe tear (MP), cellophane maculopathy (CM), stage 4 macular hole (MH) and vitreomacular traction syndrome (VMT) were examined by light microscopy and by immunocytochemistry (ICC) using antibodies marking type IV collagen, type II collagen, glial fibrillary acidic protein (GFAP), and low- and high-molecular-weight cytokeratin (MNF116). These specimens were compared with post-mortem control eyes with and without physiological posterior vitreous detachment (PVD). Light microscopy was carried out on 5-microm-thick sections cut from formalin-fixed, paraffin-embedded tissue blocks. Appropriate autoclave or enzyme pre-digestion steps were deployed to retrieve antigens for ICC. No patient had undergone previous vitreoretinal surgery or peripheral retinopexy. RESULTS: From a series of 38 patients, (13 CM, 8 MP, 16 MH and 1 VMT) a total of 20 specimens contained sufficient tissue for histology and immunocytochemistry. All specimens contained portions of inner limiting membrane (ILM) coated by GFAP-positive cells. Specimens from patients with MP and CM exhibited hyperconvolution of the ILM, which was not found in the specimens from patients with MH or VMT or in the control eyes. Hyperconvolution was associated with increased glial cell density, GFAP staining intensity and duplication of ILM basement membrane. Three cases of ERMs from the MP group contained, in addition, cytokeratin-positive cells. In the control group; post-mortem eyes with PVDs showed patchy staining of the posterior hyaloid membrane for GFAP and type 4 collagen. Post-mortem eyes with attached gel showed weak positivity of the ILM for type 4 collagen, and a monolayer of GFAP-positive cells lined the vitreous aspect of the ILM. CONCLUSIONS: These results indicate that glial cells are fundamentally important in the formation of ERMs found in this group of vitreomaculopathies. The hyperconvolution and duplication of the ILM in CM and MP were striking and distinctive features and suggest a mechanism by which these membranes exert tractional forces on the retina. Post-mortem control eyes contained a similar (but more dispersed) population of GFAP-positive cells in the region of the ILM, suggesting the primary aetiology for CM and MP may originate within the ILM. ERMs from MP cases may, in addition, contain cytokeratin-positive cells, of probable RPE origin.

Basement Membrane↗

PubMed1997

Effects of exposure to carbon disulfide (CS2) on electrocardiographic features of ischemic heart disease among viscose rayon factory workers.

The objective of the study was to evaluate viscose plant workers for electrocardiographic manifestations resulting from exposure to carbon disulfide (CS2). A total of 162 workers (118 in an exposure group and 44 in a reference group) were evaluated using a health questionnaire, physical check-up, biochemical analysis of blood samples and electrocardiograms (ECG). The exposure group consisted of workers in the following areas: viscose manufacturing, cellophane processing, ripening, and filament spinning. Reference group workers were from the administrative office, rolling area, pulp processing, and testing office. Only slight differences were found in the biochemical analyses of the two groups, with the exception of sodium (Na) levels. Personal and area sampling results were found to have a high variation due to different locations within the plant and a wide range of manufacturing processes. Highest CS2 concentrations were found in the ripening area (54.60 ppm) and the filament spinning area (19.60 ppm). Using a multiple logistic regression model to control variables (age, gender, body mass index, duration of employment, cholesterol, smoking, and alcohol), we found a relative risk for ECG abnormalities 4.18 times significantly higher for the exposure group. The authors feel that the installation of an adequate ventilation system could greatly reduce the risk of workers developing CS2-induced cardiovascular abnormalities.

Adult↗

PubMed1998

The expression of genes involved in parasitism by Trichoderma harzianum is triggered by a diffusible factor.

The mycoparasite Trichoderma harzianum has been extensively used in the biocontrol of a wide range of phytopathogenic fungi. Hydrolytic enzymes secreted by the parasite have been directly implicated in the lysis of the host. Dual cultures of Trichoderma and a host, with and without contact, were used as means to study the mycoparasitic response in Trichoderma. Northern analysis showed high-level expression of genes encoding a proteinase (prb1) and an endochitinase (ech42) in dual cultures even if contact with the host was prevented by using cellophane membranes. Neither gene was induced during the interaction of Trichoderma with lectin-coated nylon fibres, which are known to induce hyphal coiling and appressorium formation. Thus, the signal involved in triggering the production of these hydrolytic enzymes by T. harzianum during the parasitic response is independent of the recognition mediated by this lectin-carbohydrate interaction. The results showed that induction of prb1 and ech42 is contact-independent, and a diffusible molecule produced by the host is the signal that triggers expression of both genes in vivo. Furthermore, a molecule that is resistant to heat and protease treatment, obtained from Rhizoctonia solani cell walls induces expression of both genes. Thus, this molecule is involved in the regulation of the expression of hydrolytic enzymes during mycoparasitism by T. harzianum.

Base Sequence↗

PubMed2006

Synthesis and characterization of acrylic type hydrogels containing azo derivatives of 5-amino salicylic acid for colon-specific drug delivery.

pH-sensitive hydrogels are suitable candidates for oral delivery of therapeutic peptides, proteins and drugs, due to their ability to respond to environmental pH changes. Terephthalic acid was covalently linked with 2-hydroxyethyl methacrylate (HEMA), abbreviated as cross-linking agent (CA). Acryloyl ester of 5-[4-(hydroxy phenyl) azo] salicylic acid (HPAS) as an azo derivative of 5-amino salicylic acid (5-ASA) was prepared under mild conditions. The HPAS was covalently linked with acryloyl chloride, abbreviated as APAS. Free radical cross-linking copolymerization of polymerizable azo derivative of 5-ASA (APAS) and methacrylic acid (MAA) in two different molar ratios, with the various ratios CA as cross-linking agent were carried out with using 2, 2'-azobisisobutyronitrile (AIBN) as initiator at the temperature range 60-70 degrees C. The composition of the cross-linked three-dimensional polymers was determined by FTIR spectroscopy. Glass transition temperature (Tg) of the network polymers was determined calorimetrically. The hydrolysis of drug-polymer conjugates was carried out in cellophane membrane dialysis bags containing aqueous buffer solutions (pH 7.4 and pH 1) at 37 degrees C. The effect of copolymer composition on the hydrolytic degradation was studied in simulated gastric fluid (SGF, pH 1) and simulated intestinal fluid (SIF, pH 7.4) at 37 degrees C. Monitoring of the hydrolysis process by HPLC and UV spectroscopy shows that the azo prodrug (HPAS) was released by hydrolysis of the ester bond located between the HPAS and the polymer chain. The drug-release profiles indicate that amount drug release dependent on the content of MAA groups and crosslinking.

Azo Compounds↗

PubMed1990

A comparison of the filtration, concentration, and thick smear techniques in the diagnosis of Schistosoma bovis infection in cattle and goats.

The syringe and the modified Bell filtration techniques, the cellophane faecal thick smear (Kato/Katz) and Teesdale (sandwich) smear techniques, and the formol-ether concentration technique were compared for efficiency for detection of eggs of Schistosoma bovis in faeces from cattle and goats. Both filtration techniques were highly effective as revealed by high sensitivity and mean egg counts. However, efficiency declined markedly using formalin-fixed faecal material. The efficiency of the Teesdale technique was comparable to that of the filtration techniques, whereas the efficiency of the Kato/Katz technique in goats and the formol-ether concentration technique in cattle was markedly lower. The ease of performance combined with the high sensitivity make the syringe filtration and the Teesdale techniques recommendable for field diagnosis of schistosomiasis in domestic stock.

Analysis of Variance↗

PubMed1990

Geometry and pump function in cardiac ventricular hypertrophy.

Ventricular pump function can be quantified by the inverse relation between pressure and output, i.e., the pump function graph, which is obtained by varying arterial load without changing end-diastolic volume, inotropic state and heart rate. The ratio of pressure and output, i.e., the peripheral resistance, can be represented in the same graph by a line through the origin. The 2 pressure-output relations intersect in the working point, i.e., the pressure and flow at the prevailing steady state. In normal, anesthetized cats the ventricle appears to be matched to the arterial load in the sense that the working point is found at the optimal power, i.e., the optimal value of the product of pressure and output along the pump function graph. To maintain this matching criterion during pressure overload, the ventricular volume has to remain the same while thickening of the wall takes place: concentric hypertrophy. With volume overload, matching would be preserved with eccentric hypertrophy. Because volume and pressure overloads typically lead to eccentric and concentric hypertrophy, respectively, the matching criterion may be a valuable predictor of the geometric changes found with changes in load. This idea was further investigated experimentally by determining the position of the working point in the perinephritic cat that had 1 kidney removed and the other wrapped in cellophane for 15 to 26 weeks. The working point was no longer found at the optimal power, indicating that either matching was permanently comprised or that the ventricle was still trying to restore matching.

Animals↗

PubMed1990

Drying acrylamide slab gels for fluorography without using gel drier and vacuum pump.

A method for drying acrylamide slab gels for fluorography without using a gel drier and a vacuum pump is described. The method involves the use of inexpensive acrylic frames, cellophane, and plastic supplies. The fluorographs obtained from gels dried by this method are comparable to those obtained using a gel drier and a vacuum pump. Several gels can be dried by this method simultaneously at room temperature. The method is less time consuming and is economical and practically crack free.

Acrylamide↗

PubMed1989

An ultrastructural study of human epithelial rests of Malassez maintained in a differentiated state in vitro.

Healthy human periodontal ligaments (PDL), obtained from the extracted teeth (premolars and third molars), were cultivated for 1-35 days, using a multi-purposes culture chamber (MPCC) equipped with various transparent membranes. The resting state of the epithelial rests of Malassez (ERM), similar to their in vivo counterparts, appeared as small islands or strands with scant cytoplasm containing poorly developed organelles. This state was most effectively maintained in MPCC with a cellophane sheet. MPCC with a Sartorius membrane filter permitted proliferation and emigration of ERM. Proliferating ERM were characterized by more profiles of rough endoplasmic reticulum and free ribosomes, new formation of actin-containing microfilaments, less prominent tonofilaments and desmosomes and loss of gap junctions. Most of these ultrastructural changes are manifested in epithelial cells during wound healing. The emigrating ERM from PDL explants, as well as occasional proliferating ERM within explants, consisted of two cell types--outer basal-like cells, as described above, and inner tonofilament-rich prickle-like cells, suggesting a propensity for differentiation of ERM. The results show the possibility of controlling the growth and differentiation of ERM through the MPCC culture environment.

Adolescent↗

PubMed1996

Kinetic study of cutaneous and subcutaneous distribution following topical application of [7,8-14C]rac-alpha-lipoic acid onto hairless mice.

To diminish oxidative injury, topically applied antioxidants must reach susceptible cells. alpha-Lipoic acid is a potent thiol antioxidant that might be useful for skin protection; therefore, its skin penetration kinetics were assessed. The cutaneous and subcutaneous distributions of [7,8-14C]rac-alpha-lipoic acid were studied in anesthetized hairless mice after application of a 5% solution in propylene glycol for 0.5 to 4 hr. The mice were killed; then the skin was washed, and the stratum corneum was removed by 10 cellophane tape strippings. A punch biopsy of the frozen, stripped skin was sectioned, and amounts of [14C]-alpha-lipoic acid were determined in strippings and slices of epidermis (4 x 5 microns), dermis, and subcutaneous fat (10 x 10 microns, 20 x 20 microns). The rate of [14C]-alpha-lipoic acid absorption into skin was constant by 30 min (0.10 +/- 0.01 nmol/cm2/min); maximum skin concentrations were reached by 2 hr. The [14C]-alpha-lipoic acid penetration kinetics into the first layer of the stratum corneum predicted its penetration through the stratum corneum and subsequent percutaneous absorption (r2 = 0.96, P < 0.02). Cutaneous absorption of unlabeled alpha-lipoic acid and its reduction to the more potent antioxidant form, dihydrolipoic acid, were also demonstrated, using HPLC analysis with electrochemical detection. In conclusion, alpha-lipoic acid topically applied to skin penetrated readily, and was reduced to dihydrolipoic acid. Thus, alpha-lipoic acid could potentiate skin antioxidant protection.

Animals↗

PubMed1987

Multinucleate foreign-body giant cell formation.

The formation of multinucleate giant cells (MGCs) was studied after the subcutaneous implantation of cellophane foil into 25 Wistar rats. Epitheloid cells fuse to form MGCs of the Langhans type, with nuclei at the cell periphery that later migrate to the central cell region (Touton's type). Both cell types fuse again to form the monstrous MGC (more than 1 mm in diameter) widely extended on the implant surface. These cells are characterized by enlarged nuclei which are significantly larger than those in MGCs of the Langhans type. The positivity of widely extended MGCs for acid phosphatase and sodium tetrazolium reductase seems to be lower than that in Langhans' or Touton's cells. Widely extended MGCs cover a large area of implant surface and represent a barrier-like structure which separates the surrounding tissues from foreign bodies or materials that cannot be eliminated or disintegrated.

Animals↗

PubMed1993

In vitro embryonation of Syphacia obvelata eggs.

Mouse infections with the pinworm, Syphacia obvelata, were evaluated as a potential model of human enterobiasis. Eggs of S. obvelata were found to be much less resistant to adverse environmental factors than those of Enterobius vermicularis, perishing rapidly when exposed to desiccation or to water. The average number of eggs produced by a female worm was 317 +/- 29 S.D. (range: 266-347), which is about 2-3% of the fecundity of E. vermicularis. Eggs expressed from gravid S. obvelata were incubated under various conditions, but the only reliable method of supporting complete embryonation was culture on a floating cellophane membrane. At 30 degrees C on this substrate, eggs were found to be infective between 6 and 42 h, inclusive. The pre-patent period in mice fed these eggs was 11-15 days. The more fastidious developmental and survival requirements of Syphacia eggs indicate that transmission of this species depends on much more intimate contact between hosts than is required by E. vermicularis.

Animals↗

PubMed1980

Arterial connective tissue changes and distribution of 125I-labelled low density lipoprotein in hypertensive pigs.

Young pigs with hypertension of 10 weeks duration, resulting from cellophane perinephritis, were injected with 125I-labelled low-density lipoprotein ([125I]LDL) before being killed 24 h or 48 h later. Intimal thickening and increased acid mucopolysaccharide were demonstrated in the aortas and major arteries of the hypertensive animals. Increased accumulation of [125I]LDL was observed in the inner media beneath areas of intimal thickening. It is suggested that the primary effect of hypertension in atherosclerosis is to produce structural changes in arterial connective tissue which allow increased accumulation of LDL by altering the permeability and binding properties of the arterial wall.

Animals↗

PubMed1977

Human transfer factor prepared by dialysis, ultrafiltration and gel chromatography: biological activity in local transfer of skin sensitivity.

Human transfer factor (TF) was prepared by a variety of methods including dialysis using cellophane tubing, ultrafiltration through a membrane of known pore size. Sephadex G25 chromatography or combinations of some of these methods. In general the various preparations when injected locally into human skin gave greater delayed-type responses than antigen (PPD or Candida) alone. The combination of either vacuum dialysis, or ultrafiltration, with G-25 chromatography gave as good or better TF activity when compared with unchromatographed materials. Since ultrafiltration and concentration is rapid procedure and eliminates the need for freeze-drying, in contrast to vacuum dialysis against water, these results indicate that ultrafiltration and G-25 chromatography provide a convenient method for preparing large batches of relatively pure TF from leucocyte extracts.

Antigens, Fungal↗

PubMed1978

Some requirements for a linear cell dose response in vitro assay for the T-cell progenitors of cytotoxic lymphocytes.

To develop a precise assay for the T-cells progenitors of cytotoxic lymphocytes (CL-progenitors), lymphoid were cultured under optimal conditions in Marbrook vessels with mitomycin-treated allogeneic stimulator cells, and the total level of CL produced 5 days later estimated by a modified 51Cr release assay. Conditions were adjusted so an arithmetically linear cell dose response relationship was obtained. Three aspects of the cell dose response curve required attention. (1) At low responding cell inputs a macrophage-like cell became limiting (despite the presence of allogeneic macrophages in the stimulating cell population), leading to a lag in the response. This limitation was overcome by adding a low level of irradiated syngeneic macrophages, or by using irradiated syngeneic spleen 'filler' cells. (2) The slope of the resultant linear dose response region could be reduced if desired by changing from cellophane dialysis membranes to 0.1 mu pore size nuclepore membranes, suggesting a stimulatory role for some higher molecular weight soluble factor produced in the cultures. (3) At higher responding cell inputs a marked and extensive plateau was obtained. CL developing early in the response appeared to be destroying the allogeneic stimulator cells causing the response to be self-limiting. This problem was overcome by using a responding cell concentration lower than commonly employed. Assays using mixed leukocyte cultures in the lag or plateau regions could give misleading vlaues for CL-progenitor activity. It is suggested that some examples of apparent synergism in CL generation may have resulted from these effects, rather than T-cell helper T-cell progenitor interactions.

Animals↗

PubMedDate not supplied

Albendazole treatment in human taeniasis.

The results are presented of albendazole trials on human taeniasis infections in Honduras, involving 56 of 68 individuals (2% of the inhabitants) found to be infected during surveys conducted in 15 rural communities. Of the 3 methods used for diagnosis of infection, the Kato cellophane thick smear showed 80% reliability, a combination of Kato and 'Scotch' tape perianal swab 88%, and clinical history of proglottid expulsion less than 50%. Individuals were treated with a dose of 400 mg of albendazole per day for 3 d, followed for 5 d to verify tapeworm expulsion, and evaluated again at 60 and 90 d to assess drug efficacy. All 56 treated individuals remained stool-negative after 60 and 90 d; a partial strobila or segments were recovered from 21 of them (37.5%). Of these, Taenia saginata was identified from 4, and T. solium from 15; 2 specimens could not be specifically identified. Based on negative stool examinations and clinical history after 60 and 90 d, albendazole seems to be a well tolerated, very effective drug for treating infections with Taenia spp. However, confirmation of these results is needed due to the difficulty of making a reliable diagnosis of such infections.

Adolescent↗

PubMedDate not supplied

Specular microscopy in the identification of deep corneal opacities.

Specular microscopy provides a level of magnification and differentiation of detail which approaches that of a histological examination, and has the advantage of being a noninvasive procedure. This makes specular microscopy useful not only in examining the corneal endothelium, but also in identifying deep corneal opacities, which fall into two broad groups: 1) exogenous materials deposited in the cornea; and 2) endogenous pathologic corneal changes. Exogenous materials in the cornea have a wide variety of appearances, including the typical appearance of caterpillar hairs, the multifaceted appearance of glass foreign bodies, the regular geometric appearance of cholesterol crystals and cigar-shaped myeloma crystals or the more irregular deposits of chlorpromazine. Endogenous changes include ghost vessels, larger striate corneal nerves, fasciculi of fine parallel lines in keratoconus, criss-cross irregularly running lines in resolved keratitis, and a shagreen or cellophane-like appearance suggesting thickening of Descemet's membrane. While some deep corneal opacities are easily diagnosed clinically, the nature of others may be difficult to determine and specular microscopy is a valuable aid in such cases.

Corneal Diseases↗