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At least 325 records · Page 18Linked to original sources

PubMed2006

The arl locus positively regulates Staphylococcus aureus type 5 capsule via an mgrA-dependent pathway.

Most clinical Staphylococcus aureus strains produce either type 5 or type 8 capsular polysaccharides. The production of these capsules is influenced by various environmental factors. To study the regulation of capsule, Tn551 transposon mutagenesis and transcriptional reporter gene fusion were employed to identify several putative regulatory loci that influenced capsule gene expression. One of these, the arl locus, was chosen for further analysis. Tn551 was found to insert within the coding region (near the translational start site of the arlR gene). ArlR, along with ArlS, forms a two-component system that has been previously shown to affect autolysis and production of several secreted proteins. Phenotypic analyses of the arlR-specific mutant and gene fusion analyses showed that arlR activated capsule production at the transcriptional level. However, gel mobility shift assays did not support activation of the capsule genes by direct ArlR binding to the primary cap5 promoter region upstream of the operon. In contrast, it was found that arl activated mgrA, an activator for capsule production, whereas mgrA did not have a significant effect on arlR. Genetic studies supported the notion that arlR functions upstream of mgrA with respect to the regulation of capsule production, although gene fusion studies indicated that arl could also regulate capsule independently from mgrA. Collectively, the results suggest that arl positively regulates capsule production at the transcriptional level primarily through an mgrA-dependent pathway.

Bacterial Capsules↗

PubMed1994

Polysaccharide capsule-mediated resistance to opsonophagocytosis in Klebsiella pneumoniae.

The polysaccharide capsule of Klebsiella pneumoniae is an important virulence factor that confers resistance to phagocytosis. The treatment of encapsulated bacteria with salicylate to inhibit capsule expression was found to enhance the phagocytosis of encapsulated bacteria by human neutrophils only in the presence of cell surface-specific antibodies. Both type-specific rabbit antisera and anticapsular human hyperimmune globulin were employed as opsonins. Salicylate significantly enhanced phagocytosis with homologous, but not heterologous, whole-cell antisera. Antisera, diluted 1:40, no longer opsonized fully encapsulated bacteria but promoted the uptake of multiple salicylate-treated bacteria in > 90% of neutrophils. Salicylate (0.25 to 1.0 mM) also enhanced opsonization with globulin against homologous bacteria. Higher salicylate levels (1 to 2.5 mM) enhanced the opsonization of heterologous serotypes with human globulin. The nature of antibody attachment to encapsulated bacteria was determined by immunofluorescence. Even after the addition of purified capsular polysaccharide to prevent phagocytosis, K-specific antibodies attached in large amounts to bacteria. K-specific antibodies reacted with antigens throughout the capsule and showed a predilection for a denser inner layer of the capsule, indicating that many of the K-specific antibodies may be masked underneath the capsule surface. K-specific antibodies can also be rendered nonfunctional by soluble, cell-free capsular antigen. In culture, large quantities of soluble capsular polysaccharide extrude from bacteria after overnight growth. The reduction in capsule expression caused by salicylate largely affected the soluble, cell-free fraction. Purified capsular polysaccharide was shown to retard the opsonophagocytosis of salicylate-treated bacteria in a concentration-dependent manner. However, extensive washing of encapsulated bacteria to remove loosely attached capsular material did not significantly enhance opsonophagocytosis. In conclusion, cell-free capsule and cell-associated capsule are antiphagocytic; both act to neutralize K-specific antibodies by binding or concealment. Salicylate-mediated inhibition of capsule expression, particularly of the cell-free fraction, improved K-specific opsonization dramatically.

Animals↗

PubMed2003

Genetic alteration of capsule type but not PspA type affects accessibility of surface-bound complement and surface antigens of Streptococcus pneumoniae.

The Streptococcus pneumoniae capsular polysaccharides and pneumococcal surface protein A (PspA) are major determinants of virulence that are antigenically variable and capable of eliciting protective immune responses. By genetically switching the pspA genes of the capsule type 2 strain D39 and the capsule type 3 strain WU2, we showed that the different abilities of antibody to PspA to protect against these strains was not related to the PspA type expressed. Similarly, the level of specific antibody binding to PspA, other surface antigens, and surface-localized C3b did not depend on the PspA type but instead was correlated with the capsule type. The type 3 strain WU2 and an isogenic derivative of D39 that expresses the type 3 capsule bound nearly identical amounts of antibody to PspA and other surface antigens, and these amounts were less than one-half the amount observed with the type 2 parent strain D39. Expression of the type 3 capsule in D39 also reduced the amount of C3b deposited and its accessibility to antibody, resulting in a level intermediate between the levels observed with WU2 and D39. Despite these effects, the capsule type was not the determining factor in anti-PspA-mediated protection, as both D39 and its derivative expressing the type 3 capsule were more resistant to protection than WU2. The specific combination of PspA and capsule type also did not determine the level of protection. The capsule structure is thus a major determinant in accessibility of surface antigens to antibody, but certain strains appear to express other factors that can influence antibody-mediated protection.

Amino Acid Sequence↗

PubMed1998

Characterization of the gene cassette required for biosynthesis of the (alpha1-->6)-linked N-acetyl-D-mannosamine-1-phosphate capsule of serogroup A Neisseria meningitidis.

The (alpha1-->6)-linked N-acetyl-D-mannosamine-1-phosphate meningococcal capsule of serogroup A Neisseria meningitidis is biochemically distinct from the sialic acid-containing capsules produced by other disease-associated meningococcal serogroups (e.g., B, C, Y, and W-135). We defined the genetic cassette responsible for expression of the serogroup A capsule. The cassette comprised a 4,701-bp nucleotide sequence located between the outer membrane capsule transporter gene, ctrA, and galE, encoding the UDP-glucose-4-epimerase. Four open reading frames (ORFs) not found in the genomes of the other meningococcal serogroups were identified. The first serogroup A ORF was separated from ctrA by a 218-bp intergenic region. Reverse transcriptase (RT) PCR and primer extension studies of serogroup A mRNA showed that all four ORFs were cotranscribed in the opposite orientation to ctrA and that transcription of the ORFs was initiated from the intergenic region by a sigma-70-type promoter that overlapped the ctrA promoter. The first ORF exhibited 58% amino acid identity with the UDP-N-acetyl-D-glucosamine (UDP-GlcNAc) 2-epimerase of Escherichia coli, which is responsible for the conversion of UDP-GlcNAc into UDP-N-acetyl-D-mannosamine. Polar or nonpolar mutagenesis of each of the ORFs resulted in an abrogation of serogroup A capsule production as determined by colony immunoblots and enzyme-linked immunosorbent assay. Replacement of the serogroup A biosynthetic gene cassette with a serogroup B cassette by transformation resulted in capsule switching from a serogroup A capsule to a serogroup B capsule. These data indicate that assembly of the serogroup A capsule likely begins with monomeric UDP-GlcNAc and requires proteins encoded by three other genes found in the serogroup A N. meningitidis-specific operon located between ctrA and galE.

Bacterial Capsules↗

PubMed2001

Stability assessment of chitosan-sodium hexametaphosphate capsules.

The assessment of the stability of capsules based on chitosan-sodium hexametaphosphate complex formation has been carried out using two independent methods--compression and osmotic swelling, and the influence of the preparation variables was evaluated. The formulation containing 1.5% core polymer (chitosan) and 1.5% oligophosphate, in the absence of salt or at low ionic strength (0.15% NaCl) was found to provide the best membrane resistance. A higher concentration of cross-linker (2.25%) produced stable capsules only in absence of electrolyte. Mannitol, a porogen added to the preparation solutions, did not affect the stability of the obtained membranes. At elevated polyol (1%) and cross-linker levels (2.25%), and at 0% salt, membranes with decreased elasticity were obtained, having lower compression and osmotic bursting values and lower deformation at the breaking points. A significant influence of salt amount on the capsule stability was also found. This was attributed to changes in the membrane formation process resulting in membranes with different thickness and structure. Membrane compression stability was found to be dependent on the pH of both oligophosphate and chitosan solutions, as well as on the reaction time. The bursting force values decreased for capsule diameters below 1.6 mm. The increased membrane/capsule volume ratio for the small capsules decreased the capsule deformation freedom and caused capsule rupture at low force values. The capsules made at low salt amounts showed very good storage stability over time and at elevated temperatures. The results demonstrated that the capsules could be formulated with controlled properties for various biomedical applications.

Capsules↗

PubMed1988

Improvement of in vivo stability of alginate-polylysine capsules.

Dextran (MW 70,000) and rat islets were encapsulated in alginate-polylysine membrane. The capsules were further coated with tolylene 2,4-diisocyanate. Both of positive and negative charges were detected on the surface of alginate-polylysine capsules, which were absent after coating the capsules with tolylene 2,4-diisocyanate. In the peritoneal cavity, alginate-polylysine capsules were entrapped by the peritoneum, and 89% of dextran was leaked out of the capsules. Alginate-polylysine capsules coated with tolylene 2,4-diisocyanate were present freely in the peritoneal cavity and no leakage of dextran from the capsules were detected. Insulin release from the encapsulated islets was almost the same in both of tolylene 2,4-diisocyanate-coated and uncoated capsules. This study demonstrates that in vivo stability of capsules is dependent on the charge on the surface and can be improved by coating with tolylene 2,4-diisocyanate.

Alginates↗

PubMedDate not supplied

Effect of bio-adhesive polymers, sodium salicylate, polyoxyethylene-9-lauryl ether and method of preparation on the relative hypoglycemia produced by insulin enteric coated capsules in diabetic beagle dogs.

The hypoglycemic effect of oral insulin capsules coated with pH-dependent Eudragit S100 and containing various absorption promoters was studied in hyperglycemic beagle dogs. The absorption enhancers used were bio-adhesive polymers, sodium salicylate and non-ionic surfactants. A comparative study of the bio-adhesive polymers, polycarbophil (PC), hydroxypropyl methylcellulose (HPMC) and carbopol 934 in insulin coated capsules, revealed no significant difference between the insulin capsules containing these polymers giving a relative hypoglycemia (RH) values ranged from 4.3 +/- 2.3% to 6.5 +/- 5.1%. It was also found that the method of preparation of the mixture of the bio-adhesive polymer with insulin either by physical mixing or freeze-drying did not affect the RH values obtained. Sodium salicylate, when used in insulin enteric coated capsules (50 mg) mixed with insulin as a physical mixture or prepared by wet granulation using 10% polyvinyl pyrollidone (PVP) or by freeze drying, produced RH values ranged from 7.3 +/- 2.9 to 9.4 +/- 3.7%. When sodium salicylate (100 mg) was used with insulin in freeze-dried granules an RH value of 10 +/- 2.6% was produced. As the dose of insulin increased from 6 to 9 U/kg, the AUC of the enteric coated capsules containing 50 mg sodium salicylate increased from 73.2 +/- 27.8 to 121.4 +/- 102.7% reduction but the RH id not significantly change. Insulin capsules containing polyoxyethylene-9-lauryl ether (POELE) used in its optimum concentration (2%), found in these experiments, produced a RH of 9.5 +/- 6.8% when prepared as granules by wetting with few drops of absolute alcohol in presence of PC (50 mg). Insulin capsules containing lower (1%) or higher (3%) concentrations of POELE and prepared with PC, 50 mg by wet granulation produced lower RH of about 6%. The enteric coated oral insulin capsules containing insulin (6 or 9 U/kg) and sodium salicylate (50 mg) as an absorption promoter together with the bioadhesive polymer polycarbophil (50 mg) and prepared either by wet granulation using ethanol or by freeze drying are the best formulations to be used. They achieved a reduction in plasma glucose levels of about 25-30% and RH of about 10%. Also insulin (9 U/kg) capsules containing 2% POELE produced 28% reduction in plasma glucose levels and RH of 9.6 +/- 6.8%.

Animals↗

PubMed2004

Prevention of posterior capsule opacification using different intraocular lenses (results of one-year clinical study).

AIM: To evaluate and to compare the preventive effect of different intraocular lenses from different material with a round or sharp optic edge design on posterior capsule opacification. METHODS: Our clinical study included 165 patients. Mean follow-up was 12.4+/-0.9 months, mean patient age was 67.5+/-7.8 years. Patients in the group 1 (n=46) were implanted acrylic three-piece hydrophobic intraocular lenses, sharp optic edge (AcrySof, MA3OBA, Alcon), in the group 2 (n=38)--acrylic hydrophobic single piece intraocular lenses, sharp optic edge (AcrySof, SA3OAL, Alcon), in the group 3 (n=39)--silicone three-piece intraocular lenses, sharp optic edge (CeeOn 911A, Pharmacia), and in the group 4 (n=42)--polymethyl methacrylate single piece intraocular lenses, round optic edge (Crystal, 5T, Alcon). The posterior capsule opacification was evaluated for the entire optic and in the central 3-mm zone using EPCO 2000 Software. RESULTS: Posterior capsule opacification values of the entire optic were 0.002+/-0.001 in the AcrySof MA3OBA group, 0.007+/-0.002 in the AcrySof SA3OAL group, 0.002+/-0.001 in the CeeOn 911A group, 0.029+/-0.008 in the polymethyl methacrylate intraocular lens group 6 months after surgery. The values were 0.011+/-0.005, 0.025+/-0.006, 0.014+/-0.005 and 0.122+/-0.021, respectively, one year after surgery. The intraocular lenses types with sharp-edge design (acrylic and silicone) showed significantly lower posterior capsule opacification values than round-edge optic design polymethyl methacrylate lenses (p<0.05). Posterior capsule opacification values of the central 3-mm zone were 0.000+/-0.000 in the AcrySof MA3OBA group, 0.001+/-0.001 in the AcrySof SA3OAL group, 0.000+/-0.000 in the CeeOn 911A group, 0.002+/-0.001 in the polymethyl methacrylate intraocular lens group 6 months after surgery. The values were 0.0001+/-0.0001, 0.018+/-0.007, 0.004+/-0.002 and 0.028+/-0.009, respectively, one year after surgery. Posterior capsule opacification values differences between AcrySof MA3OBA and polymethyl methacrylate intraocular lenses' groups and between CeeOn 911A and polymethyl methacrylate intraocular lenses' groups one year after cataract surgery were established (p<0.05). CONCLUSIONS: The sharp-edge foldable intraocular lenses types (AcrySof MA3OBA, AcrySof SA3OAL, CeeOn 911A) showed statistically significant difference in posterior capsule opacification values in one-year follow-up time. The effect of these foldable lenses for prevention of posterior capsule opacification is mainly a result of rectangular, sharp-edged optic design, which creates a sharp capsular bend. A role of material of intraocular lenses (hydrophobic acrylate and silicone) in prevention of posterior capsule opacification during one-year follow-up was not established.

Acrylic Resins↗

PubMed2005

[Clinical pathological study of the anterior lens capsule abnormalities in familial congenital aniridia with cataract].

OBJECTIVE: To observe the pathological changes of the lens and anterior lens capsule of the patients with familial congenital aniridia, and discuss the histopathological etiology of the fragility of the anterior capsule and the significance of surgical project. METHODS: Anterior lens capsules and lens specimens were obtained from aniridic patients during cataract surgery. The intraoperative behavior of each capsule was noted, after which the specimens were submitted for histopathologic evaluation and electron microscope examination. RESULTS: The anterior lens capsule was extremely fragile and remarkably thin. Degenerative changes(degeneration, necrosis, loss) of the lens epithelium and discontinuity of the lens epithelium were found in some specimens. Proliferation and double layer of the epithelial cells in some area of the specimens can be seen also. Ply structure of the anterior capsule became thin or disappeared. CONCLUSION: Degenerative or proliferative changes of the lens epithelial cells were associated with the thinness and extreme intraperative fragility of the anterior lens capsules in familial aniridia with cataract. Greater awareness of anterior capsule fragility in some aniridic patients with cataract may reduce the risk of capsule complications and lead to safer surgical outcomes.

Adolescent↗

PubMed2006

[Effect of suyu capsule on behavior and injury of hippocampal neurons in depression model mice].

OBJECTIVE: To observe the effect of Suyu capsule on behavior, injury of hippocampal neurons and Ca2+ ion in hippocampal synaptic in the depression model mice. METHOD: Sixty male Kunming mice were randomly divided into 5 groups, the control group, the model group and three Suyu capsule groups (the doses were 22.8, 11.4, 5.7 g x kg(-1) respectively). The model was established by separation and chronic unpredictable mild stimulation. The increased weight and crossing score, rearing score were measured by open-field and sweet water consumption of mice. Cone cell and configuration of neuron in CA1, CA3 region of hippocampus were observed by Nissl. The concentration of hippocampal synaptic Ca2+ ion was detected by fluorimetry. RESULT: Comparing with the mice of control, the increased weight was slowered ( P < 0.01), the scores of rearing and crossing were decreased (P < 0.01), sweet water consumption were decreased too (P < 0.01), numbers of cone cell in CA3 region of hippocampus were decreased obviously (P < 0.01), and Ca2+ ion in hippocampal synaptic was increased obviously. Comparing with the mice of model, Suyu capsule (22.8 g kg(-1)) could increase the increased weight on the 14th and 21 st day obviously (P < 0.05); Suyu capsule (22.8 g x kg(-1)) could increase the scores of crossing obviously (P < 0.05), Suyu capsule (22.8, 11.4 g x kg(-1)) could increase the scores of rearing obviously (P < 0.01, P < 0.05); Suyu capsule (22.8, 11.4, 5.8 g x kg(-1)) could increase sweet water consumption obviously (P < 0.01, P < 0.05, P < 0.05; Suyu capsule (22.8, 11.4, 5.8 g x kg(-1)) could increase numbers of cone cell in CA3 region of hippocampus obviously (P < 0.01, P < 0.05, P < 0.05); Suyu capsule (22.8, 11.4, 5.8 g x kg(-1)) decreased Ca2+ ion in hippocampal synaptic with dose-effect relationship (P < 0.01, P < 0.01, P < 0.05). CONCLUSION: Suyu capsule can improve all the symptoms of the depression model mice and protect injury of hippocampal neurons in the depression model mice. The possible mechanism of action is to restrict Ca2+ ion overfreight.

Animals↗

PubMed2006

Does capsule endoscopy recognise gastric antral vascular ectasia more frequently than conventional endoscopy?

BACKGROUND: Gastric antral vascular ectasia (GAVE) is a rare cause of obscure gastrointestinal bleeding which can be difficult to recognise endoscopically. Capsule endoscopy is primarily designed to image the small bowel, but may identify gastric and colonic lesions. There have been few reported cases of GAVE diagnosed by capsule endoscopy in the literature. OBJECTIVE: Our aim was to assess the frequency of GAVE in patients with obscure gastrointestinal bleeding referred for capsule endoscopy. DESIGN: Case series. SETTING: This study was conducted in a tertiary referral hospital. PATIENTS. This study comprised 128 consecutive patients with obscure gastrointestinal bleeding. INTERVENTIONS: All patients underwent capsule endoscopy. RESULTS. Six patients were diagnosed with GAVE on the basis of the capsule endoscopy findings (4.7%, five female, median age 71.5 years). All patients had previously had numerous gastrointestinal investigations prior to capsule endoscopy. Five patients to date have been treated with argon plasma coagulation of their vascular lesions. This has resulted in stabilisation of their haemoglobin and cessation of blood transfusions in 4/5 cases with an average follow up period of 15 months. CONCLUSIONS: GAVE is commonly missed at gastroscopy and accounted for 4.7% of patients referred for capsule endoscopy with obscure gastrointestinal bleeding (in our series). This case series represents the largest number of GAVE recognised by capsule endoscopy. In the presence of any of the reported risk/associated factors for GAVE the gastroenterologist interpreting the capsule images should have a high index of suspicion.

Aged↗

PubMed1982

An investigation of drug expectancy as a function of capsule color and size and preparation form.

Much of a drug response is related to nonspecific factors. Perceptual characteristics of drug preparations likely play a major role in expectancy and response. This study focused on perceptual characteristics of a preparation related to anticipated effect: capsule color, capsule size, and preparation form (capsule versus tablet). College students ranked capsules for perceived strength based on capsule size, categorized capsules in terms of anticipated pharmacological effect based on color, and evaluated strength based on preparation form. Data showed nonchance distributions for nine capsule colors in anticipated action, with specific effects for four colors. A significant difference between capsule and tablet for perceived strength was found, as was a trend relating capsule size to perceived drug strength. Discussion centered on awareness and consideration of drug perceptual characteristics in support of drug efficacy.

Adult↗

PubMed1994

Quality control of extemporaneously prepared microdose captopril capsules: weight variation versus content uniformity.

Microdose (1 mg) captopril therapy is commonly used for the initial dose titration in patients with congestive heart failure. Since this dosage form is not commercially available, it has to be extemporaneously compounded. Quality control of each batch is commonly evaluated using the weight variation technique described in the USP. Despite careful titration with microdose, captopril capsules variability in patient's response has been observed. In order to explain this fluctuation, the actual content of extemporaneously compounded microdose captopril capsules was evaluated using a high pressure liquid chromatographic assay. Microdose captopril capsules were prepared by triturating 25 mg tablets with lactose in a mortar using standard geometric dilution technique and a Sharpe-Dohme hand-operated capsule filling machine. Forty-eight microdose captopril capsules were randomly selected from the compounded batch and were individually assayed for captopril amount. The mean +/- standard deviation (SD) amount of captopril in each capsule was 1.27 g +/- 0.31 mg with a range of 0.84 g to 1.96 mg. The coefficient of variation was 24.5%. Ten captopril capsules were randomly selected from the compounded batch and were individually weighed. The capsules had a mean weight +/- SD of 198.3 g +/- 21.2 mg and a coefficient of variation of 7.3%. Even though the extemporaneously prepared microdose captopril capsules were within acceptable limits for weight variation described in the USP, the actual dose administered to the patients could vary by as much as 24.5%.

Capsules↗

PubMed1996

A study of human lens cell growth in vitro. A model for posterior capsule opacification.

PURPOSE: After intraocular lens (IOL) implant surgery for cataract, cell growth on the posterior capsule is responsible for renewed visual impairment in approximately 30% of patients. The authors have, therefore, developed a human lens capsule system to study this growth in vitro. METHODS: Sham cataract surgery, including anterior capsulorhexis, nucleus hydroexpression, and aspiration of lens fibers, was performed on donor eyes. In some cases, a polymethylmethacrylate IOL implant was placed in the capsular bag. The capsular bag was dissected free, pinned flat on a plastic culture dish, covered with Eagle's minimum essential medium supplemented with 10% fetal calf serum and observed by phase-contrast and dark-field microscopy for as long as 100 days. At the end-point, capsules were examined by fluorescence microscopy for actin, vimentin, and chromatin. RESULTS: Within 24 hours, there was evidence of cell growth in the equatorial region. After 2 to 3 days, cells were normally observed growing from the rhexis onto the posterior capsule and across the anterior surface of the IOL, if present. Growth proceeded rapidly so that the posterior capsule, for example, was totally covered by a confluent monolayer of cells at 5.8 +/- 0.6 days and 7.2 +/- 0.7 days for capsules aged < 40 years and > 60 years, respectively. Total cover of the anterior IOL surface generally followed 4 to 5 days behind that of the capsule. Capsular wrinkles became increasingly apparent as time progressed, causing a marked rise in light scatter. An increase in capsular tension also occurred, and the actin filaments became more polarized near the wrinkles. CONCLUSIONS: The model presented here for posterior capsule opacification shows many of the changes seen in vivo, including rapid lens cell growth, wrinkling, tensioning, and light scatter in the posterior capsule. It will be possible to develop strategies for inhibiting cell growth with this system.

Actins↗

PubMed1998

Tuft-to-capsule adhesions and their precursors: differences between the vascular and tubular poles of the human glomerulus.

Human glomerular capillary tufts were removed by microdissection and scanning electron microscopy was used to examine the surface of the capillary tuft and the interior of its Bowman's capsule in order to identify connections between the tuft and capsule. Glomeruli were examined in histologically normal renal cortex from 12 kidneys removed for tumour and 12 renal allografts removed for end-stage rejection. In normal kidney, the glomerular tuft was connected to Bowman's capsule by single podocytes and their processes. At the vascular pole, these were predominantly associated with parietal podocytes which lined Bowman's capsule. At the tubular pole, occasional podocytic processes derived from the capillary tuft bridged Bowman's space and connected to Bowman's capsule where there were no parietal podocytes. These podocytic connections were also found in all rejected transplants, but in addition adhesions were identified which consisted of thicker connections between the tuft and capsule. At the vascular pole, tuft-to-capsule adhesions were found in all 12 kidneys; these were always associated with parietal podocytes. Tubular pole adhesions were identified in ten of the 12 transplants. They were associated with abnormal squamous cells, but not with parietal podocytes. When the capillary tuft herniated into the proximal tubule, the tuft sometimes formed an adhesion with the origin of the proximal tubule. These observations suggest that podocyte connections between the glomerular tuft and Bowman's capsule may be precursors of glomerular adhesions at the vascular pole. Since tuft-to-capsule adhesions at the vascular pole differ morphologically from those at the tubular pole, this may reflect different pathogenetic mechanisms at the opposite poles of the glomerulus.

Chronic Disease↗

PubMed1997

Biochemical changes in the equine capsule following prostaglandin-induced pregnancy failure.

The equine embryonic capsule, an acellular covering that envelops the conceptus during the second and third weeks of pregnancy, is composed of mucin-like glycoproteins. Its structure is consistent with a dual role during early pregnancy: protection of the conceptus, and communication between the embryo and the mother. Loss of sialic acid from the capsular glycoproteins at day 16 correlates with the time of "fixation," or loss of conceptus mobility throughout the uterine horns. This study investigated how the structure of the capsule is linked to the maintenance of pregnancy. Six pregnancies, confirmed by ultrasound, were terminated by prostaglandin injection on day 14, prior to the time of embryo fixation. These "defective" conceptuses were collected at day 17, and the structure and molecular properties of their capsules were compared to those of day 17 conceptuses collected from 5 normal pregnancies. Defective capsules were not significantly different from normal capsules in terms of dry weight, amino acid composition, and content of neutral and amino sugars. However, defective capsules failed to show the loss of sialic acid normally occurring around the time of embryo fixation. Analysis of the capsular mucins following trypsin digestion was carried out by radioactive labeling with 3H on sialyl-oligosaccharides and 125I on tyrosine residues, followed by fast protein liquid chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis. Differences in the trypsin fragmentation patterns indicated increased susceptibility of the defective capsules to proteolysis. We conclude that there is a temporal association between desialylation of the equine capsule and embryonic survival, and that failure to desialylate alters the properties of the capsule.

Abortion, Induced↗

PubMed2002

Tissue responses against immunoisolating alginate-PLL capsules in the immediate posttransplant period.

Alginate-polylysine (PLL) capsules are commonly applied for immunoisolation of living cells for the treatment of a wide variety of diseases. Large-scale application of the technique, however, is hampered by insufficient biocompatibility of the capsules with failure of the grafts as a consequence. Most studies addressing biocompatibility issues of alginate-PLL capsules have focused on the degree of overgrowth on the capsules after graft failure and not on the reaction against the capsules in the immediate posttransplant period. Therefore, capsules were implanted in the peritoneal cavity of rats and retrieved 1, 5, and 7 days later for histological examination and X-ray photoelectron spectroscopy analysis for evaluation of chemical changes at the capsule surface. After implantation, the nitrogen signal increased from 5% on day 0, to 8.6% on day 7, illustrating protein adsorption on the capsule's surface. This increase in protein content of the membrane was accompanied by an increase in the percentage of overgrown capsules from 0.5 +/- 0.3% on day 1 to 3.3 +/- 1.6% on day 7. The cellular overgrowth was composed of monocytes/macrophages, granulocytes, fibroblasts, erythrocytes, multinucleated giant cells, and basophils. This overgrowth was not statical as generally assumed but rather dynamic as illustrated by our observation that at day 1 after implantation we mainly found monocytes/macrophages and granulocytes that on later time points were substituted by fibroblasts. As the inflammatory reaction predictably interfere with survival of encapsulated cells, efforts should be made to suppress activities or recruitment of inflammatory cells. These efforts may be temporary rather than permanent because most inflammatory cells have disappeared after 2 weeks of implantation.

Alginates↗

PubMed1976

The form and function of cnidarian spirocysts. 2. Ultrastructure of the capsule tip and wall and mechanism of discharge.

The electron-dense capsule tip (apical cap) of sea anemone and coral spirocysts is of a different structure than the capsule wall. The capsule wall is composed of a double layer of fiber-like materials which cross each other at roughly right angles. The innermost layer is characterized by numerous serrations, the tips of which project into the lumen of the capsule. Within each serration, a band of finely cross-striated material encircles the capsule at right angles to its longitudinal axis. The membrane lining the lumen of the capsule appears to be continuous with the wall of the undischarged thread. The outer capsule wall layer consists of closely spaced microfilaments (cnidofilaments) which are oriented in the longitudinal axis of the capsule. The cnidofilaments appear to merge with the apical cap material. Contrary to some previous reports in the literature, it has been found that spirocysts normally discharge by eversion, as do nematocysts. The relationship of the capsule wall sub-structure to the spirocyst discharge process is discussed.

Animals↗