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Biomedical subjects

D J Ferguson

Publications and source records attributed to D J Ferguson.

At least 199 records · Page 11Linked to original sources
PubMed1979

Ultrastructural studies on the sporulation of oocysts of Toxoplasma gondii. II. Formation of the sporocyst and structure of the sporocyst wall.

The ultrastructural changes observed during sporocyst formation and the structure of the sporocyst wall was examined in oocysts which had been allowed to sporulate for between 12 and 48 hours at 27 degrees C. As the spherical sporoblast developed into the sporocyst the cytoplasmic mass became ellipsoidal in shape although no change was noted in the organelle compliment, which cosisted of two nuclei plus a number of polysaccharide granules, lipid globules, mitochondria, Golgi bodies, and some rough endoplasmic reticulum. The sporocyst wall consisted of a thin outer layer (15-20 nm) which was formed from two limiting membranes of the sporoblast and an inner layer (40-50 nm) which was comprised of four curved plates. This inner layer was formed under the outer layer and, although no specific cytoplasmic organelle disappeared with its formation, some unit membranes were observed close to the plasmalemma during its formation. Each curved plate has a marginal swelling and an interposing strip of material is present between the margins of adjacent plates. The plates are joined to the interposing strip by a thin band of osmiophilic material. In oblique and tangential sections through the plates two types of cross banding were observed which differed in periodicity.

Cell Wall↗
PubMed1979

Electron microscopy of a filamentous, segmented bacterium attached to the small intestine of mice from a laboratory animal colony in Denmark.

A filamentous, segmented bacterium was observed in the small intestine of the SSC:AH stock of mice from the Statens Seruminstitut (Denmark) animal colony but was absent in golden hamsters and guinea pigs from the same colony. The bacterium is attached to the epithelial cell by a special segment (holdfast) and causes specific changes in the epithelial cell at the site of attachment. Once attached the bacterium appears to undergo a complex life cycle which involves the development of a long filament divided into a number of segments within which holdfasts or spores are formed. This organism is morphologically identical to a bacterium found in mice and rats in the USA, but this is the first report of such an infection in Europe.

Animals↗
PubMed1979

An ultrastructural study on the excystation of the sporozoites of Toxoplasma gondii.

The ultrastructural changes which occur during the in vitro excystation of the sporozoites of Toxoplasma gondii were examined. The excystation was carried out at 37 degrees C on suspensions of oocysts which had been ground and then treated with an excysting medium containing 0.25% trypsin and 0.75% sodium taurocholate in phosphate buffered saline, pH 7.3. It was found that sporocysts within intact oocysts were unaffected while sporocysts exposed to the medium ruptured. The sporocyst wall consisted of two layers and during excystation the four plates which form the inner layer started to curl inward. At the same time changes were seen at the specialized junctions between these plates. When the junctions finally break, the plates separate. The outer layer of the sporocyst wall is then ruptured at points directly above where the plates were joined. Each of the four portions of the sporocyst wall curled inward to form a tightly wound whorl. The sporozoites can escape through the openings created between the portions of the sporocyst wall.

Animals↗
PubMed1978

Observations on the ultrastructure of the sporocyst and the initiation of sporozoite formation in Toxoplasma gondii.

The ultrastructure of the immature sporocyst and the initiation of sporozoite formation in T. gondii was examined in oocysts which had been allowed to sporulate for 12 or 24 hours at 27 degrees C. The sporocyst was ellipsoidal in shape and possessed a two layered sporocyst wall. A nucleus, with associated Golgi bodies, was situated at either end of the organism. The cytoplasm of the sporocyst also contained a number of polysaccharide granules, lipid globules, mitochondria and a few strands of rough endoplasmic reticulum. Sporozoite formation was initiated by the appearance of two dense plaques at either end of the organism in the vicinity of a nucleus, adjacent to the limiting membrane of the organism.

Cell Membrane↗
PubMed1978

Light and electron microscopy on the sporulation of the oocysts of Eimeria brunetti. I. Development of the zygote and formation of the sporoblasts.

The initial stages of sporulation in oocysts of Eimeria brunetti were examined in samples sporulated at 27 degrees C for 0, 12 and 24 hours. The initial zygote was found to be roughly spherical and to contain a number of polysaccharide granules which were congregated in one region of the organism. The cytoplasm also contained some strands of rough endoplasmic reticulum together with a number of mitochondria, some Golgi bodies, and some electron translucent vacuoles. The nucleus was large, with amorphous nucleoplasm and a nucleous. The cytoplasmic mass of the zygote was limited by a single unit membrane which possessed some micropores. After initiation of the sporulation, the metabolic activity of the organism appeared to increase as evidenced by the augmentation in the cytoplasm of the amounts of rough endoplasmic reticulum, number of Golgi bodies, and the appearance of polyribosomes. However, at this stage, the presence of large spherical bodies (anlagen of the refractile bodies of the sporozoites) constituted the most obvious change in the cytoplasm of the organism. After nuclear division the daughter nuclei were situated well separated in the cytoplasm and the polysaccharide granules were evenly distributed throughout the cytoplasm of the zygote. Eventually four sporoblasts were formed by invaginations of the limiting membrane. Each sporoblast was limited by a unit membrane and contained a nucleus, and the same cytoplasmic organelles as found in the zygote. The development of the sporoblast was initially accompanied by the appearance of a second limiting membrane.

Cytoplasm↗
PubMed1978

Light and electron microscopy on the sporulation of the oocysts of Eimeria brunetti. II. Development into the sporocyst and formation of the sporozoite.

The later stages of sporulation in oocysts of Eimeria brunetti were examined in samples which had been allowed to sporulate at 27 degrees C for 24, 36 and 48 hours. It was observed that the sporoblasts became ellipsoidal and the nucleus underwent the final division. A nucleus with associated Golgi bodies was not observed at either end of the organism. The cytoplasm was limited by two unit membranes and contained rough endoplasmic reticulum, dense bodies, electron translucent vacuoles and mitochondria. The first evidence of sporozoite formation was the appearance of a dense plaque at either end of the organism. This appeared in the vicinity of the nuclei, and adjacent to the limiting membrane of the soroblast. At this stage the sporocyst wall was still unformed. Then the two sporozoites were formed from opposite ends of the organism by growth of the dense plaques and invaginations of the plasmalemma which thus formed the pellicles of the developing sporozoites. A conoid and subpellicular microtubules were observed at this stage as development continued, a number of vacuoles were found between the nucleus and the conoid. These vacuoles constituted the precursors of the rhoptries and micronemes. At the same stage a large dense body had appeared within the forming sporozoite. As the sporozoite developed, this body, anterior refractile body, is followed by the nucleus and another dense body which formed the posterior refractile body. During this period, the thin sporocyst wall was formed and Stieda and sub-Stieda bodies were now present at one end of the sporocyst. Each mature sporocyst contained two sporozoites.

Cytoplasm↗
PubMed1977

Selection of chemotherapy for metastatic mammary cancer by effect on cesium-131 uptake.

Cesium-131 was administered intravenously to 39 patients with superficial metastases of mammary carcinoma and the concentration in tumor was compared with that in normal tissue by application of a detector in vivo, before and after 1 to 5 days of chemotherapy with cyclophosphamide (CP), 5-fluorouracil (FU), or diethylstilbestrol. A change of the cesium concentration ratio (tumor/normal tissue) greater than 15% after brief treatment correctly predicted the therapeutic effect after 1 to 39 months on the tumors that were tested in 30 of 33 tests. No reliable correlation could be made in the remaining 21 tests in which the change of ratio was less than 15%. The concentration of cesium-131 in the skin, fat, and skeletal muscle of mice was not appreciably altered by treatment for 5 days with CP or FU.

Antineoplastic Agents↗
PubMed1977

Ultrastructural studies on the endogenous development of Eimeria brunetti. II. Microgametogony and the microgamete.

The ultrastructural changes of Eimeria brunetti which occur during microgametogony in the small intestine of the domestic fowl are described. The development of the trophozoite into the microgametocyte was accompanied by cytoplasmic growth and nuclear division. The developing microgametocytes could be differentiated from developing schizonts because of ultrastructural differences in both cytoplasm and nuclei. The surface area of the microgametocyte was increased by deep invaginations of the limiting membrane. At this developmental stage, the nuclei were situated adjacent to this membrane and protrusions which developed, initiated microgamete formation. Two centrioles were positioned between each nucleus and the limiting membrane and were transformed into the basal bodies of the flagella. The flagella grew out from the basal bodies which then entered the protrusions. A mitochondrion and the dense chromatin-containing portion of the nucleus also entered each protrusion. The microgametes matured while they were attached to the residual cytoplasm of the microgametocyte; they were finally budded off into the parasitophorous vacuole. The microgamete consists of an elongated nucleus which overlaps a mitochondrion towards the arterior of the cell. At this end, a dense plaque (perforatorium) is found together with the 2 basal bodies and their attached flagella. 5 microtubules were apparent and ran longitudinally from the basal body region. In cross section they were arranged in a row of 4 with 1 diagonally opposite; only 2 of these microtubules extended to the posterior tip of the microgamete.

Animals↗
PubMed1977

Ultrastructural studies on the endogenous development of eimeria brunetti. III. Macrogametogony and the macrogamete.

The ultrastructural changes occurring during macrogametogony in Eimeria brunetti were studied in tissue from the small intestine of infected young domestic fowls. As the macrogametocyte developed, an increase in the volume of the cytoplasm and the nucleus occurred. At this early stage of development the organism was limited by a single unit membrane which possessed a number of micropores. The organism was situated in a parasitophorous vacuole which contained intra-vacuolar folds and intra-vacuolar tubules. The wall forming bodies of type II (WFB II) started to appear before the wall forming bodies of Type I (WFB I). The WFB I developed in the cytoplasmic matric whereas the WFB II were formed within the cisternae of the rough endoplasmic reticulum apparently in association with Golgi bodies. The mature WFB I were homogeneous, limited by a unit membrane, and larger than WFB II which had no limiting membrane but remained surrounded by a membrane of the rough endoplasmic reticulum. Polysaccharide granules were formed in the cytoplasm between strands of the rough endoplasmic reticulum. During maturation the WFB I & II and the polysaccharide granules increased in size and number, and as this occurred a number of electron translucent vacuoles were ejected from the surface of the macrogametocyte. The mature macrogamete possessed a large nucleus with a nucleolus, a number of multi-membranous vacuoles, mitochondria, and canaliculi. The WFB I & II were located at the cell periphery and the polysaccharide granules further towards the interior of the organism. The organism was limited by a unit membrane but during macrogametogony a homogeneous layer had developed which extensively coated the macrog...

Animals↗
PubMed1977

Observations on the ultrastructure of the late sporoblasts and the initiation of sporozoite formation in Eimeria brunetti.

The ultrastructure of the late sporoblast and the initiation of sporozite formation in E. brunetti was examined in oocysts which had been allowed to sporulate for 24 hours at 27 degrees C. The late sporoblast was ellipsoidal in shape and possessed two nuclei, and with associated Golgi bodies, situated at either end of the organism. Its cytoplasm contained numerous polysaccharide granules, electron translucentral region of the plaques. Sporozoite formation was similar to the initiation of merozoite formation in the schizont. Endodyogeny did not appear to be involved in the process of sporozoite formation.t vacuoles, dense bodies, mitochondria, and some strands of rough endoplasmic reticulum. The sporoblast, at this stage, was enclosed by two unit membranes. Sporozoite formation was initiated by the appearance of a dense plaque at either end of the organism in the vicinity of a nucleus, adjacent to the limiting membrane of the sporoblast. A conoid was present in the central region of the plaques Sporozoite formation was similar to the initiation of merozoite formation in the schizont. Endodyogeny did not appear to be involved in the process of sporozoite formation.

Animals↗
PubMed1977

Ultrastructural studies on the endogenous development of Eimeria brunetti. IV. Formation and structure of the oocyst wall.

The ultrastructural changes occurring during wall formation in the oocysts of E. brunetti were studied in tissue from the small intestine of young domestic fowls. The process of oocyst wall formation was initiated by a separation of the limiting membranes of the cytoplasmic mass of the macrogamete, to form a loose veil, consisting of 2-3 membranes, around the organism. Concomitant with the appearance of the veil, changes were observed in the Wall Forming Bodies of Type I (WFB I) and Type II (WFB II) which were present in the cytoplasm of the macrogamete. The outer layer of the oocyst wall seemed to be formed by a combination of membranes released from the surface of the organism and the contents of the WFB I. A 700 nm thick layer was thereby formed and, at this stage, the WFB I had disappeared from the cytoplasmic mass. The outer layer further condensed into a structure 250-350 nm in thickness in which 3 zones of different densities could be distinguished. The formation of the inner layer of the oocyst wall appeared to be associated with material from the WFB II and these disappeared from the cytoplasmic mass as the inner layer became evident. This inner layer was homogeneous in appearance and 80 nm thick. Comparison of the ultrastructure of the walls of oocysts obtained from chicken faeces with that of oocysts observed within the intestine showed only minor differences. The loose veil was not present in oocysts isolated from faeces and some changes were also noted in the outer zone of the outer layer of the oocyst wall. These differences could result from the mechanical and chemical treatments used for processing the faeces.

Animals↗
PubMed1977

Cytochemical electron microscopy on polysaccharide granules in the endogenous forms of Eimeria brunetti.

The endogenous stages in the life cycle of Eimeria brunetti were tested for polysaccharide material by electron microscopical cytochemistry using the periodic acid-thiocarbohydrazide-osmium tetroxide (PATO)-method. The parasites were observed within the epithelial cells of the small intestine of infected domestic fowls. Two types of granules reacted positively for polysaccharide. The first was large, approximately 500 nm by 250 nm. These granules had an appearance similar to the polysaccharide granules reported for other coccidian parasites. They were observed in mature merozoites, macrogamonts, and developing oocysts. The second type of granule was smaller (15-30 nm in diameter) and was only observed at the periphery of the residual cytoplasmic mass of mature microgamonts. It was more similar in appearance to metazoan glycogen than the former. However, since the PATO-method does not differentiate between different polysaccharides it can not be proven if these granules in fast contain glycogen. The WFBI of the macrogamete and the outer layer of the oocyst wall gave a slight positive reaction but after examination of the controls it appeared that this was not a specific reaction for polysaccharides.

Cytoplasmic Granules↗
PubMed1977

The ultrastructure and distribution of micropores in the various developmental forms of Eimeria brunetti.

The structure and distribution of micropores in the various developmental stages of Eimeria brunetti was examined. Micropores were observed in all the endogenous forms with the exception of the microgamete. Oocysts from chicken faeces were also examined at various stages of sporulation and micropores were demonstrated in zygotes, sporoblasts, sporozoites, and the residual cytoplasmic masses. The number of micropores per organism appeared to be correlated with the surface area of the organisms irrespective of whether these were endogenous or sporulating forms. The increase in the number of micropores did not appear to be related to micropore activity because semmingly active micropores were observed only in the trophozoites, in the early multinucleate forms (early shizonts and microgamonts), and in the early macrogamonts. All these forms, however, possessed relatively few micropores. No active micropores were ever observed within the sporulating oocysts.

Animals↗
PubMed1977

Prognostic classification of Hodgkin disease in pathologic stage III, based on anatomic considerations.

Fifty-two patients with pathologic stage III Hodgkin disease were studied in an effort to determine whether location of involved abdominal nodes influenced survival. Treatment consisted of total nodal radiotherapy with or without subsequent combination chemotherapy. Th initial radiation field was the "extended mantle," which included supradiaphragmatic nodes, the splenic hilar area, and paraaortic nodes to the level of L2-L4. Subsequently, lower paraaortic and iliac regions were treated ("lower inverted Y"). Patients with disease limited to the spleen and/or splenic, celiac, or portal nodes ("anatomic substage" III1) had a more favorable 5-yr survival than did patients with involvement of paraaortic, iliac, or mesenteric nodes ("anatomic substage" III2): 93% versus 57%, respectively (p less than 0.05). The addition of combination chemotherapy to total nodal irradiation was associated with improved survival of patients in stage III2, but not of those in stage III1.

Hodgkin Disease↗
PubMed1977

Cellular attachment to implanted foreign bodies in relation to tumorigenesis.

Previous experiments demonstrating a reduction of tumorigenicity by roughening the surfaces of plastics implanted in rodents, or by increasing the pore size of cellulose filter implants, were repeated with observations on cellular attachment to these objects and to filters strengthened and made impermeable by bonding to plastic. Round 13-mm discs of methylmethacrylate implanted S.C. in A/BiF/F50 + mice produced sarcomas in 12 percent of mice at 64 weeks. Tumor incidence increased to 60 percent (p less than 0.001) in mice receiving discs to which cellulose filters with pore sizes of 0.025 to 0.1 micrometer were bonded. No tumors occurred with discs covered by 0.45-micrometer filters, followed up to 83 weeks. Vinyl coverslips 15 mm square also produced no sarcomas when covered by 0.45 micrometer filters; plain vinyl produced sarcomas in 40 percent of mice at 64 weeks (p less than 0.001). Sanding of vinyl surfaces reduced tumorigenicity (p less than 0.05). Permeability, fragility, and storage capacity of filters are apparently not related to tumorigenicity. Surface roughness probably is related. Cells, mostly macrophages, were densely and uniformly attached to nontumorigenic surfaces from 24 hr to 2 years after inplantation but were distinctly fewer and not uniformly distrubuted on tumorigenic surfaces. Topology favoring attachment was inherent in 0.45-mum filters and was produced in plastic by gouging irregular excavations 10 to 15 micrometer deep.

Animals↗