Atoxoplasma (Apicomplexa: Eimeriorina: Atoxoplasmatidae) in the greenfinch (Carduelis chloris).

Merozoites of an Atoxoplasma species were present within parasitophorous vacuoles in the cytoplasm of leucocytes in the blood vessels in the small intestine of the greenfinch (Carduelis chloris). The merozoites indented the nucleus of the leucocytes. Merozoites, macrogametes, and microgamonts were present in the epithelial cells of the intestines.

Crohn's disease: pathogenesis and persistent measles virus infection.

The Inflammatory Bowel Disease Study Group at the Royal Free Hospital School of Medicine has tested the hypothesis that the primary pathological abnormality in Crohn's disease is in the mesenteric blood supply. Early morphological studies involved arterial perfusion-fixation and either resin casting and scanning electron microscopy or vascular immunostaining of resected intestine affected by Crohn's disease. Granulomatous and lymphocytic damage to intramural blood vessels, even in macroscopically normal areas, was observed.

Ultrastructural observations on the third-generation merozoites of Eimeria tenella in chicks.

The fine structure of the third-generation merozoites of Eimeria tenella is described from caecal enterocytes of chicks 120 h after experimental infections. The merozoites conformed to the general eimerian pattern except that they were bounded by two unit membranes. Young gamonts also conformed to the general eimerian pattern, and were limited by an outer unit membrane and an interrupted inner membrane.

Ultrastructural observations on caecal epithelial cells invaded by first-generation merozoites of Eimeria tenella in vivo.

Transmission electron microscopy was used to study the effects of invasion of caecal epithelial cells by first-generation merozoites of Eimeria tenella. At 53 h post-infection, merozoites were found within mature meronts and in enterocytes of the crypt epithelium. Following merozoite invasion, the terminal web of microfilaments of the invaded cell was disrupted and cell extensions were present on the enterocyte surface.

Evidence of persistent measles virus infection in Crohn's disease.

Transmission electron microscopy was used to examine the microvasculature of perfusion-fixed tissues from Crohn's disease and control patients. Paramyxovirus-like particles, and inclusions consisting of condensations of nucleocapsid, in giant cells and endothelium at foci of vascular injury were identified in all 9 Crohn's disease patients. Tissues from patients with Crohn's disease were also examined by either in situ hybridisation (n = 10) or immunohistochemistry (n = 15), and compared to inflammatory and noninflammatory controls (n = 22).

Desaggregation by Verapamil, Sodium Nitroprusside and PGE(1), of Rabbit Platelets Aggregated by PAF-acether. A Morphological and Biochemical Study.

The action of sodium nitroprusside, an activator of guanylate cyclase, on rabbit platelets stimulated with PAF-acether, was studied singly or in combination with verapamil. Not only did sodium nitroprusside in the range 10(-6) to 10(-4) M inhibit PAF-acether induced aggregation, but it also brought about desaggregation of previously aggregated platelets, as also did verapamil. The results were compared with those obtained with PGE(1), when used alone and in combination with verapamil.

Granulomatous vasculitis in Crohn's disease.

This study investigated a possible vascular origin for granulomas in Crohn's disease. Twenty-four consecutive resected specimens of small and large intestinal Crohn's disease were preserved by arterial perfusion-fixation with 10% formol saline, at mean arterial pressure (100 mm Hg). Fifteen specimens contained granulomas on routine examination of H&E-stained sections.

Ultrastructural studies of the effects of the ionophore lasalocid on Eimeria tenella in chickens.

The ultrastructural development of Eimeria tenella was studied in experimentally infected chicks fed 90 ppm lasalocid, an ionophorous anticoccidial antibiotic. Drug treatment was timed to target-specific endogenous stages. At 6 h after infection, many sporozoites within the epithelium showed degradation as a result of drug action.

Nicotine and cigarette smoking: effects on the ultrastructure of aortic endothelium.

The aortic endothelium from rats has been examined by scanning (SEM) and transmission electron microscopy (TEM) following nicotine administration or cigarette smoking. Nicotine was administered to rats by subcutaneous injections at concentrations of 1, 5, 10 and 20 mg/kg or by continuous subcutaneous pumps delivering a solution of 0.54 g/ml of nicotine at the rate of 1 microliter/h for 7 days.

Effect of lasalocid on the development of Eimeria tenella in chicken embryos.

Sporozoites of Eimeria tenella were treated with lasalocid in vitro and their viability tested by inoculating them into the allantoic cavity of 11-day-old chicken embryos. Concentrations of 0.1, 1.

Repopulation of guinea-pig skin by melanocytes during wound healing: a morphometric study.

Epidermal keratinocytes and melanocytes have a close functional interrelationship. In order to study this relationship we used computer-assisted three-dimensional morphometry (CAM) to investigate the shape and size changes of the cutaneous melanocyte in healing guinea-pig skin. The combination of CAM with osmium iodide staining and resin embedding of tissue gave excellent results and allowed qualitative and quantitative morphometric assessment of melanocytes in vertical epidermal sections.

Pathogenesis of Crohn's disease: multifocal gastrointestinal infarction.

In a prospective study, specimens of resected small and large intestine from fifteen patients with Crohn's disease were prepared by heparin-saline vascular perfusion, followed by either resin casting of the mesenteric vascular supply and tissue maceration or glutaraldehyde perfusion-fixation, resin casting, and tissue clearance. The specimens were examined by macrophotography, histopathology, and either scanning or transmission electronmicroscopy. A pathogenetic sequence of events in Crohn's disease was seen--vascular injury, focal arteritis, fibrin deposition, arterial occlusion mainly at the level of the muscularis propria, followed by tissue infarction or neovascularisation.

Effects of autologous mesothelial cell seeding on prostacyclin production within Dacron arterial prostheses.

Canine abdominal aortas have been replaced with Dacron arterial prostheses to assess the effects of mesothelial cell seeding on graft prostacyclin and thromboxane A2 release. At both 2 weeks and 6 weeks after surgery, three seeded and two unseeded control grafts were examined for prostacyclin release. In addition, thromboxane release was assessed in one seeded and one unseeded graft.

The effect of nicotine on human endothelial cell release of prostaglandins and ultrastructure.

The acute and sub-acute effects of nicotine at concentrations between 10(-9)M and 10(-2)M on human umbilical vein endothelial cell release of prostacyclin and prostaglandin E2 and the sub-acute effect on the endothelial cell ultrastructure have been examined. The acute effect of nicotine on prostaglandin release has been assessed by measuring release of prostacyclin and prostaglandin E2 following stimulation of confluent monolayers of endothelial cells with A23187 in the presence of nicotine. The sub-acute effect has been assessed by measuring A23187 stimulated release of prostacyclin and prostaglandin E2 from endothelial cells grown to confluence in the presence of nicotine.

Ultrastructural observations of microgametogenesis in Eimeria bakuensis (Syn. E. ovina) of sheep.

The ultrastructure of microgametogenesis of Eimeria bakuensis was studied in the intestinal epithelium of an experimentally infected sheep. During development the nuclei became situated peripherally in the microgamont. Nuclear chromatin condensed into peripheral, dense portions that became the nuclei of the microgametes.