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Biomedical subjects

E B Ilgren

Publications and source records attributed to E B Ilgren.

32 records · Page 2Linked to original sources
PubMed1981

On the control of the trophoblastic giant-cell transformation in the mouse: homotypic cellular interactions and polyploidy.

Trophoblastic tissues grown under different conditions in vitro display distinct patterns of cellular growth. Thus, trophoblast cultured on 'bacteriological grade' plastic surfaces remained in suspension culture as rounded tissue fragments. Such tissues maintained numerous cell contacts and remained, in turn, largely diploid. Trophoblast explanted on a 'tissue-culture grade' substrate formed monolayers. These contained fewer cell contacts and had more giant nuclei than the rounded tissues. Finally, if trophoblast was dissociated and grown as attached single cells, so that cell contact was minimal or absent, the single-cell preparations contained more giant nuclei than tissues grown either as monolayers or in suspension. These results suggest that changes in tissue shape and the number of cell contacts can modify the growth of mouse trophoblast and alter its ability to become giant.

Animals↗
PubMed1980

Polyploidization of extraembryonic tissues during mouse embryogenesis.

It has recently been shown that visceral yolk-sac endoderm is derived from the primitive endoderm of the 4.5-day mouse blastocyst (Gardner & Papaioannou, 1975; Gardner & Rossant, 1979). During development, primitive endodermal cells acquire nuclei with more than four times the haploid amount of DNA. The finding of metaphases with multiple sets of chromosomes suggests that the diploid precursors of such endodermal giant cells become truly polyploid. Amniotic cells also contain giant nuclei but the mechanism by which these arise is uncertain. The giant-cell transformation therefore appears to be a general feature of mouse extraembryonic development rather than a phenomenon restricted solely to trophoblast. The basis and significance of these findings are discussed in relation to the development of other extraembryonic membranes both of plant and animal origin.

Animals↗
PubMed1980

The control of trophoblastic growth in the guinea pig.

The growth of mouse trophectoderm depends upon the presence of the inner cell mass. Whether this applies to other species of mammals is not known. To investigate this problem, the guinea pig was selected for two reasons. Firstly the growth of guinea-pig trophoblast resembles that of man. Secondly, earlier studies suggest that the proliferation of guinea-pig trophectoderm may not be under ICM control. Therefore, in the present study, the guinea-pig blastocyst was cut microsurgically to yield two tissue fragments. These contained roughly equal numbers of trophectodermal cells, one fragment being composed only of trophectoderm and the other containing ICM tissue as well. Subsequently, the growth of these mural and polar fragments was followed in vitro since numerous technical difficulties make an in vivo analysis of this problem impracticable. In the manner similar to the mouse, the isolated mural trophectoderm of the guinea pig stopped dividing and became giant. In contrast, guinea-pig polar fragments formed egg-cylinder-like structures. The latter contained regions structurally similar to two presumptive polar trophectodermal derivatives namely the ectoplacental and extraembryonic ectodermal tissues. These findings suggest that guinea-pig trophectodermal growth may occur in a manner similar to the mouse and thus be under ICM control.

Animals↗
PubMed1977

Pneumoperitoneum without ruptured viscus in the neonate: a case report and review of the literature.

A premature infant with severe respiratory distress developed the clinical and radiologic signs of pneumoperitoneum. At operation, free intraperitoneal air without visceral perforation was found. This case is unique in that pneumothorax was never observed and that interstitial emphysema or ischemic gastrointestinal lesions were not present at autopsy. The patient, however, was on a positive pressure ventilator for some time because of hyaline membrane disease and early pulmonary oxygen toxicity. Reduced parenchymal compliance could predispose to alveolar rupture. Although there was no clinical or anatomic evidence to point to a source of the intraperitoneal air, an undetectable pulmonary rupture with prompt dissection into the peritoneal cavity is the most likely explanation for the pneumoperitoneum.

Emphysema↗
PubMedDate not supplied

The initiation and control of trophoblastic growth in the mouse: binucleation and polyploidy.

Initially diploid, pure trophectodermal derivatives were dissociated and grown in culture. Over the 72-hour time course in vitro, uninucleate, binucleate and a small number of multinucleate cells appeared. Moreover, the pattern of binucleation found in these trophoblast cultures resembled that seen during the development of the mouse liver. Thus, the binucleates displayed a progressive increase in nuclear DNA content and the increased DNA values ranged from 2c to 32c. Furthermore, the proportion of uninucleate and binucleate cells changed systematically with growth in vitro and the final binucleate cell population became, on average, 10 to 15 per cent of the total. These results, together with those of other studies, suggest that mouse trophoblast can initially become giant through a binucleate phase.

Animals↗
PubMedDate not supplied

Placental polyploidization: a comparative study in the mouse and the guinea pig.

The trophoblastic and endodermal tissues of the guinea pig were cytophotometrically examined at two stages of development, either shortly after the primary trophoblastic giant cell layer had degenerated (Sansom and Hill, 1931) and the visceral yolk sac was starting to form (Kaufman and Davidoff, 1977) (c. 10.5 days p.c. at the egg cylinder stage) or later in gestation, when the yolk sac was well developed (c. 17.5 days p.c. at the neural tub closure stage). Subsequently, the trophoblastic and endodermal tissues of the mouse were analysed in a manner identical to those of the guinea pig. Finally, the nuclear DNA content values from the analysis of the tissues of each species were compared. The results thus obtained indicate firstly that, in the guinea pig, polyploid nuclei also appear within visceral endoderm after the primary trophoblastic giant cells degenerate and, secondly, that placental specialization in the rodents, as originally defined by Mossman (1937), apparently tends towards lower levels of polyploidy within trophoblast and higher levels within the derivatives of visceral endoderm.

Animals↗
PubMedDate not supplied

Cerebellar astrocytomas. Part I. Macroscopic and microscopic features.

Some of the pathological features of 112 cerebellar astrocytomas seen at The Radcliffe Infirmary between 1938 and 1984 have been described. These include the following: Macroscopic appearance: Cerebellar astrocytomas, when compared to other gliomas, have an unusual tendency to become cystic. Thus, if all ages are considered only 22% are total solid tumors while the others have either a large solitary cyst or many smaller ones. Although patients with cystic tumors remain free of recurrence far longer than those with totally solid astrocytomas, the proportion of cystic and solid elements does not significantly influence the overall survival period. Moreover, the degree of tumor demarcation is not an absolute indicator of the degree of malignancy. Extent of disease: Approximately 8% of cerebellar astrocytomas infiltrate the brainstem and these cases are associated with the poorest prognosis. Supratentorial invasion is very rare and CSF dissemination is very uncommon. Only one example of the latter was recorded in the present study. It is important to note that subarachnoid spread may also occur from histologically benign tumors as well as malignant cerebellar astrocytomas. Classification by growth pattern: The classification of cerebellar astrocytomas by "growth pattern" is clearly of limited use. This is due to the presence of substantial transitional forms in both the "juvenile" and "diffuse" as well as in the "fibrillary" and "protoplasmic" classifications. Confusion also arises because of the disregard for the quantity and distribution of certain features which, in turn, limits the usefulness of the "A" and "B" type classification system. Failure to define rigorously the cell type which predominates in the "cerebral" and "diffuse" forms also creates substantial difficulties in using Ringertz' nomenclature. Further problems are caused by Zülich's "polar spongioblastomas" since cerebellar astrocytomas are not composed of primitive spongioblasts, the "polar spongioblastomas" merely representing one subtype of cerebellar astrocytoma, namely the piloid or pilocytic variety. Attempts to classify cerebellar astrocytomas in a manner which does not rely upon any specific cell type but which depends instead upon the degree of homogeneity or heterogeneity of cell growth is of limited value. Grading schemes: Although the tumors studied in the present report were not graded, previous authors have shown that "grading schemes" are of little predictive value in assessing the behavior of cerebellar astrocytomas.(ABSTRACT TRUNCATED AT 400 WORDS)

Astrocytoma↗
PubMedDate not supplied

Cerebellar astrocytomas. Part II. Pathologic features indicative of malignancy.

The pathologic features which denote poor clinical outcome in a series of 112 cerebellar astrocytomas seen at The Radcliffe Infirmary, Oxford between 1938 and 1984 have been described. These have been reviewed in relation to the findings of numerous other reports in the literature. The conclusions reached are as follows: Pleomorphism: A substantial proportion of cerebellar astrocytomas display significant nuclear and cytoplasmic size variation. This is particularly common after the age of ten. Markedly pleomorphic tumors are, moreover, associated with a very short survival time. Mitotic Figures: Mitotic figures are seen in 8.5% of cerebellar astrocytomas but are found in large numbers, in only 1.1% of cases. They are more common in adults and in totally solid tumors. The presence of any mitotic figures in cerebellar astrocytomas is associated with a marked reduction in survival to death and also a noticeable increase in the rate of recurrence. Cellularity: Marked focal hypercellularity is seen in 13.2% of cerebellar astrocytomas and is especially common in childhood tumors. When marked, it is associated with a significant reduction in survival time to death. Desmoplasia: Desmoplastic reactions adjacent to tumor are seen in one-half of all cerebellar astrocytomas but are only marked in 16% of cases. When marked, however, they are associated with a reduction in overall survival time. Perivascular Pseudorosettes: These are seen in 80.9% of all cerebellar astrocytomas. When found in large numbers, they are more commonly seen in children than in tumors with a mixed cystic and solid form. Their appearance is associated with a favorable outcome when found in association with microcystic change and endothelial hyperplasia but when found in isolation they are associated with poor survival. Necrosis: Small necrotic foci are found in 16.8% of cases. Markedly necrotic tumors are very rare and are more commonly seen in patients with short histories and associated with very poor outcome. Definite malignant features: 1. Pleomorphism, if marked; 2. Mitotic figures, in any number; 3. Cellularity, if marked; 4. Desmoplasia (probably) if marked; 5. Perivascular pseudorosettes, in isolation without microcystic change and endothelial hyperplasia; 6. Necrosis, if marked. Primary malignant cerebellar astrocytomas: These tumors are rare and represent cerebellar astrocytomas with one or more areas containing the aforementioned malignant features. Primary glioblastomas of the cerebellum: These tumors are also rare and resemble both clinically and pathologically glioblastomas found in other parts of the nervous system.(ABSTRACT TRUNCATED AT 400 WORDS)

Astrocytoma↗
PubMedDate not supplied

Chemodectoma of the cauda equina: case report.

Well-differentiated paragangliomas have been found in unusual sites where conspicuous paraganglions are not normally found. A patient with a chemodectoma of the cauda equina is described. The importance of differentiating such tumors from those far more commonly seen in the region of the cauda equina, namely, ependymomas, hemangioblastomas, and metastatic carcinomas is emphasised.

Cauda Equina↗
PubMedDate not supplied

Ependymomas: a clinical and pathologic study. Part I. Biologic features.

A series of 102 Oxford ependymomas was analyzed by comparing certain clinical data with pathologic data obtained by a review of the histologic slides of the tumors. All the data analysis was performed by computer, thus permitting a rapid search of many parameters for relationships of statistical significance. Age and site were found to be associated with the duration of pre-operative symptoms, mitotic index, tumor cell number, and some specific histologic features.

Adolescent↗
PubMedDate not supplied

Clinical and pathological studies of brain injuries in horse-riding accidents: a description of cases and review with a warning to the unhelmeted.

We present a clinical and pathological study of brain injuries in horse-riding accidents. Among six fatal cases, all experienced riders varying in age and sex, two were not wearing helmets and four had inadequate protective headgear. Among five non-fatal cases, four wore adequate helmets and only one of these suffered permanent neurological damage. The fifth was not wearing a helmet and although he eventually returned to work, a CT scan following the fall showed a deep-seated perithalamic hematoma. These findings are consistent with those of virtually all other studies in that they suggest that the present type of riding helmet is inadequate and largely unable to absorb the shock of a normal fall. We hope these findings will serve as a warning to those who choose to ride unhelmeted.

Adolescent↗
PubMedDate not supplied

Ependymomas: a clinical and pathologic study. Part II. Survival features.

A survival analysis of cases of ependymoma was performed. Patients with ependymomas of the infratentorium were found to have shorter disease-free intervals and to live for a shorter time after treatment than those with tumors of the cauda equina. Children with infratentorial tumors did not have a recurrence if they survived 3 or more years after operation, whereas adults with infratentorial tumors could have a first recurrence even 5 or more years after surgery. Younger patients did not survive as long as older patients in the group of infratentorial ependymomas. In contrast, age did not influence survival in patients with cauda equina ependymomas. Patients with ependymomas of the infratentorium and the cauda equina having long histories had a better prognosis than those with short histories. Changes in mitotic index and tumor cell number could not be correlated with the length of survival. In the infratentorial group, patients with rosette-bearing tumors had a poor prognosis, whereas patients with subependymal areas in their tumor had a better prognosis. Total surgical removal with no further treatment appeared to be as effective as subtotal removal followed by radiotherapy for the cauda equina tumors.

Adolescent↗