The pulmonary veins.
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Arteriovenous Malformations↗
Biomedical subjects
V McDonald
Publications and source records attributed to V McDonald.
Computed tomography and magnetic resonance imaging of the pericardium.
Computed tomography is an established modality for the evaluation of the pericardium. It is used to evaluate complicated pericardial effusions, pericardial thickening, calcific pericarditis, pericardial cysts, postoperative changes and primary and metastatic neoplasms of the pericardium. Magnetic resonance imaging is being used with increasing frequency in the evaluation of pericardial disease. It offers advantages over computed tomography, including a potential for tissue characterization, absence of ionizing radiation or need for intravenous contrast medium, and the ability to scan in any plane. Disadvantages include greater cost, longer examination times and the inability to identify calcification positively.
Heart Neoplasms↗
Eimeria tenella: immunological diversity between asexual generations.
In the development of a normal strain, WIS, of Eimeria tenella there are three generations of schizogony whereas in an attenuated line, WIS-F-96, derived from WIS, the second and third are absent. Chickens immunized by infection with WIS-F-96, however, were highly resistant to oral challenge with sporulated oocysts of WIS, and histological studies indicated that the immune response was directed against the sporozoites from that challenge inoculum. When challenge of the WIS-F-96-primed chickens consisted of second generation merozoites of WIS (inoculated intracaecally), immunity was less pronounced and the histological data indicated that the merozoites proceeded to develop normally in these birds. These indications of immunological diversity between the merozoites of the first and second generations of schizogony of E. tenella WIS correlated with the results of preliminary studies of the antigenic composition of these developmental stages.
Animals↗
Eimeria tenella and E. necatrix: a third generation of schizogony is an obligatory part of the developmental cycle.
The latter part of endogenous development of Eimeria tenella and E. necatrix was examined in sections of cecal tissue taken from chickens infected either by giving oocysts orally or by injecting merozoites into the cecum. The findings, with 3 strains of E. tenella and 1 of E. necatrix, indicate that the majority, if not all, of the parasite populations undergo a third generation of schizogony and then embark upon gametogony.
Animals↗
The endogenous development of virulent strains and attenuated precocious lines of Eimeria tenella and E. necatrix.
Studies were made of the endogenous development of the H strains of E. tenella and E. necatrix, and precocious lines derived from them. Second-generation meronts of both precocious lines matured at a faster rate than those of the parent strains. The first- and second-generation meronts of the precocious line of E. necatrix and the second-generation meronts of the precocious line of E. tenella were significantly smaller and contained fewer merozoites than the corresponding stages of the parent strains. These observations provide reasons for the precocity, and a partial explanation for the attenuation, of these lines.
Animals↗
Eimeria maxima: characteristics of attenuated lines obtained by selection for precocious development in the chicken.
Both the Weybridge strain and a mixture of six laboratory and field strains of Eimeria maxima have been attenuated by selection for early maturation of oocysts during serial passage in chickens. The prepatent times of the resultant precocious lines produces after selection were reduced from approximately 120 hr to less than 107 hr, and their reproduction and pathogenicity were less than those of the parent strains. Chickens which had been inoculated with a small number of oocysts of the Weybridge precocious or mixed field isolate precocious lines were immune to subsequent challenge with the parent strains. In a comparison made between the endogenous development of the precocious lines and their parent strains, it was found that asexual multiplication of the precocious lines was reduced, due to the earlier onset of gametogony. The results of this study also indicate that the parent (i.e., normal) strains of E. maxima probably undergo a minimum of four generations of schizogony.
Animals↗
Eimeria tenella: immunogenicity of the first generation of schizogony.
The life-cycle of a precocious and attenuated line (WisF96) of Eimeria tenella, derived from the Wisconsin (Wis) strain, contained only the first of the three generations of schizogony undergone by the parent strain. The reproductive capacity of WisF96 was less than that of the parent strain by a factor of about 2000, but inoculation of chickens on two occasions with a large number of its oocysts induced resistance against challenge with oocysts, or with second-generation merozoites of Wis. The immunizing abilities of the attenuated line and its parent were compared by priming groups of chickens with numbers of oocysts of WisF96 or Wis, designed to produce infections of equal magnitude in terms of oocysts production (standard inocula), and then challenging with oocysts of Wis. The results suggested that an equivalent parasite mass of WisF96 was more immunogenic than Wis. This was confirmed by the finding that, even when the priming dose of Wis was increased 10-fold, the standard inoculum of WisF96 still produced the greater protective effect. These results indicate that the first generation of schizogony of E. tenella is highly immunogenic.
Animals↗
Genetic recombination of markers for precocious development, arprinocid resistance, and isoenzymes of glucose phosphate isomerase in Eimeria acervulina.
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Adenine↗
Levator muscle reconstruction: resulting velopharyngeal competence--a preliminary report.
The purpose of this study was to evaluate a levator muscle reconstruction procedure on the basis of resulting velopharyngeal competence. Ages of the patients at time of surgery ranged from 5 months to 7 years. The patients were reevaluated postoperatively. If the patients were judged to have normal nasality and no nasal emission, the procedure was considered to have yielded a satisfactory result. If hypernasality and nasal emission resulted, the patients were examined utilizing nasoendoscopy and/or videofluoroscopy. If velopharyngeal incompetence was confirmed, the operative procedure was judged to be successful. Results showed that 60 percent success was achieved. The age range which yielded the best results (73 percent satisfactory) was 37 to 60 months. The data also revealed that the more severe the cleft, the less likely this operative procedure is to produce satisfactory results. The authors recommend continued evaluation of this procedure, preferably utilizing prospective studies.
Age Factors↗
Attenuation of Eimeria species: further characterisation of two lines of Eimeria mitis.
The immunogenicity of a 'precocious' and attenuated line (HP10) of Eimeria mitis was studied and the stability of attenuation of two precocious lines was compared with that of an embryo-adapted line. Chicks housed in wire-floored cages and given 1 X 10(5) oocysts of the HP10 line were protected against challenge with the parent Houghton strain and two field strains, but remained partially susceptible to the Durham and one other field strain. However, when chicks were kept in litter pens so that reinfection could occur freely, inoculation with as few as 1 X 10(3) oocysts of the precocious line resulted in complete immunity to both the Houghton and Durham strains for at least five weeks afterwards. The stability of attenuation of the precocious and embyro-adapted lines was examined by relaxing the selection pressures used to produce attenuation and then testing the virulence of the resulting lines. The precocious lines remained attenuated after several consecutive relaxed passages, in contrast to the embyro-adapted line which showed a marked reversion to virulence after six passages in chickens.
Animals↗
Eimeria mitis: a comparison of the endogenous developmental stages of a line selected for early maturation and the parent strain.
The endogenous development of the Houghton (H) strain of Eimeria mitis (= mivati) was compared with the life-cycle of a precocious (HP) line derived from the H strain. In both parasites 4 generations of schizonts which developed in epithelial cells were observed: the 1st and 2nd were found in the crypts and the 3rd and 4th in the villi. Gametocytes and zygotes occupied epithelial cells at the tips of the villi. The onset of gametogony normally coincided with the maturation of 4th-generation schizonts. The infection was confined initially to an area of the gut extending from the jejunum to the ileo-caecal junction but 3rd-generation merozoites and subsequent stages were also found in the caeca and rectum. The life-cycle of the precocious line was shorter than that of the parent strain. Gametocytes appeared to develop from 3rd-generation as well as from 4th-generation merozoites. Also, sporozoites of the precocious line transformed to trophozoites before those of the parent strain. First-generation schizonts of the HP line tended to be smaller and to contain fewer merozoites than those of the H strain. The differences between the life-cycles of the two parasites account for the lower reproductive potential of the precocious line.
Animals↗
Further investigation of the pathogenicity, immunogenicity and stability of precocious Eimeria acervulina.
Attenuated lines of Eimeria acervulina were isolated between 62 and 72 h post-infection from the Houghton (H) strain. The inoculation of small numbers of oocysts of precocious (HP) lines gave substantial protection to Light Sussex chicks kept on litter against challenge with the virulent H strain. The precocious trait of the 72 h HP line was shown to be stable because the kinetics of oocyst production remained unaltered after 9 consecutive passages through birds in which only late developing oocysts were used for passage. The precocious 62 h HP line was subjected to further selection for 5 consecutive passages. The resultant (62 A HP) line was shown to be more attenuated than the 72 h HP line but remained capable of immunizing chicks against challenge with the H strain.
Animals↗
Attenuation of Eimeria mivati (= mitis) by selection for precocious development.
By selection for early development of oocysts during serial passage through chickens the pre-patent period of the Houghton (H) strain of Eimeria mivati (= mitis) was reduced by over 20 h. The precocious parasite is less pathogenic than the H strain and has a reduced reproductive potential. Chicks inoculated with the precocious parasite were protected against challenge with the H strain. The pathogenicity, immunogenicity and reproduction of precocious E. mivati and an attenuated egg-adapted line of E. mivati were compared. Although the precocious parasite produced more oocysts than the egg-adapted parasite in chickens, neither parasite induced loss of weight and both were immunogenic.
Animals↗
A preliminary study of the nature of infection and immunity in chickens given an attenuated line of Eimeria acervulina.
The Houghton (H) strain of Eimeria acervulina was attenuated by serial passage through chickens of the first oocysts produced during infection. This selection pressure resulted in a reduction in the pre-patent period of the parasite, shown to be due to the selection of a line predominantly with only 3 instead of 4 generations of schizonts. The precocious line had a reproductive potential much lower than that of the parent strain and it was significantly less pathogenic. Chickens given oocysts of the precocious line were almost completely immune to challenge with the Houghton strain.
Animals↗
Plasmodium iophurae: immunization of Pekin ducklings with different antigen preparations.
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Animals↗
Eimeria spp. from the chicken: from merozoites to oocysts in embryonated eggs.
Merozoites of 5 species of Eimeria from the chicken were recovered from this host and inoculated into the allantoic cavity of embryonated chicken eggs. The merozoites developed into sexual stages in the chorio-allantoic membranes, and oocysts of all the species which were tested - E. acervulina, E. brunetti, E. maxima, E. necatrix and E. praecox - were recovered. Many of the oocysts of E. maxima and E. necatrix, and a few of those of E. brunetti, sporulated and were found to be infective for chickens.
Animals↗
Plasmodium chabaudi: adoptive transfer of immunity with different spleen cell populations and development of protective activity in the serum of lethally irradiated recipient mice.
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Animals↗