Search PubMed⌕ Search

Biomedical subjects

G Morgan

Publications and source records attributed to G Morgan.

At least 307 records · Page 17Linked to original sources
PubMed1983

Cell migration in the ruminant placenta: a freeze-fracture study.

In the ruminant placenta, binucleate cells normally migrate out of the trophectodermal epithelium throughout pregnancy to fuse with the syncytium bounding the maternal connective tissue. This study shows that they form part of the trophectodermal tight junction as they migrate, thus maintaining the barrier function while penetrating the junction. This method of migration seems to be unique and the means by which it is achieved is briefly discussed.

Animals↗
PubMed1983

Ceftazidime as a single agent in the management of children with fever and neutropenia.

Fifty consecutive episodes of fever in neutropenic children with malignant disease or aplastic anaemia were randomized to treatment with either ceftazidime alone or a combination of azlocillin and tobramycin, pending the results of bacteriological investigation. More than 90% of organisms isolated from these episodes were sensitive to ceftazidime, which appears to be a non-toxic alternative to aminoglycosides in such circumstances.

Adolescent↗
PubMed1983

Human T cell clones allospecific for HLA-DR5 antigen with the OKT8 phenotype.

Human allospecific T-lymphocyte clones reactive in the primed lymphocyte (PLT) and/or the CML assays were established and grown using T cell growth factor and weekly stimulation with a pool of allogeneic feeder cells. Specificity of selected clones was determined by their reactivity with a panel of HLA-typed lymphocytes. The phenotype of the clones was identified by monoclonal antibodies and complement lysis. Two weakly cytolytic clones, which specifically proliferated in response to DR5 bearing lymphocytes in PLT, possessed the OKT8 marker, suggesting that this determinant is not exclusively involved in the recognition of class I antigens.

Antibodies, Monoclonal↗
PubMed1982

Antigenic diversity in the human malaria parasite Plasmodium falciparum.

Monoclonal antibodies against blood forms of Plasmodium falciparum were used to demonstrate considerable antigenic diversity in this species. Different isolates were distinguished by their ability to react with certain antibodies, and most of the antibodies reacted specifically with merozoites, schizonts, or both. The distribution of different antigenic types appeared not to be related to geographic origin. Serological typing with monoclonal antibodies extends the range of methods for identification of different strains of this malaria parasite.

Animals↗
PubMed1982

A freeze-fracture study of tight junction structure in sheep mammary gland epithelium during pregnancy and lactation.

Freeze fractures of the tight junctions at the apices of sheep mammary secretory cells showed that the junction at 72 d of pregnancy was significantly wider than at any later stage. The number of ridges in the junction only increased significantly between 122 and 142 d of pregnancy. The initially even distribution of intramembrane particles across the tight junction changed gradually until in the fully lactating animal there were far more particles on the lateral surface of the plasmalemma. Possible correlations between these changes, the alterations in permeability of the mammary epithelium, and the differences in hormone levels are briefly discussed.

Animals↗
PubMed1982

Mapping of transcription initiation and termination signals on Xenopus laevis ribosomal DNA.

We have injected cloned derivatives of Xenopus laevis ribosomal genes into X. laevis oocyte nuclei and examined the resulting transcription complexes in the electron microscope. From this work we conclude that the promoter lies somewhere within a region between -320 nucleotides upstream and +113 nucleotides downstream from the site of transcription initiation. This assignment agrees with inferences based on sequence conservation. It further suggests that the duplicated initiation region sequences located further out in the spacer ("Bam islands") are not required for the normal high densities of RNA polymerase loading seen on ribosomal genes. Concerning termination, the cluster of four Ts that forms part of the HindIII restriction site at the 3' end of the gene appears to be part of the normal termination signal. Termination still occurs when only three Ts are present, but reduction to two Ts damages termination. Because clusters of three Ts appear at several sites within the gene, it is likely that sequences adjacent to the T cluster also are required for normal termination. In addition, we present evidence for a fail-safe termination site just upstream from the site of transcription initiation.

Animals↗
PubMed1981

Study of an H-2Kd mutant strain: C.B6-H-2dm4.

A new H-2 mutant involving the H-2d haplotype is described--C.B6-H-2dm4 (dm4). This mutant strain carries a gain and loss mutation which maps to the Kd gene of the H-2 complex. Serological testing comparing the mutant and the parental BALB/cKh strain failed to detect any difference between the two strains and no antibodies could be produced, although a reciprocal mixed lymphocyte reaction was observed between mutant and parent.

Absorption↗
PubMed1981

Ir gene function in an I-A subregion mutant B6.C-H-2bm12.

The B6.C-H2bm12 (bm 12) strain has a mutation in the I-A subregion of the murine H-2 complex and is characterized by a loss of serologically detected Ia antigens and a strong graft rejection and mixed lymphocyte response between parent and mutant. It was presumed that the mutation affected the Ia-1 gene and to determine the relationship of Ia antigens and Ir genes, the immune responses of mutant and parent were compared. The immune responses to poly(L-Tyr,LGlu)-poly(DLAla)--poly(LLys), poly(Phe,Glu)-poly(DLAla)--poly(LLys), and poly(His,Glu)-poly(DLAla)--poly(LLys) in parent and mutant were same, indicating the Ia-1 and the Ir genes for these antigens are not identical. By contrast, although C57BL/6 gave a good response, the mutant strain was unable to generate cytotoxic T lymphocytes to the male-specific H-Y antigen--a response under I-A subregion Ir gene control, which now must be considered to be the Ia-1 gene. In addition, complementary Ir genes in the H-2b haplotype for the H-Y immune response could be detected when the bm12 mutant was used.

Animals↗
PubMed1981

Postural deformities in congenital nephrotic syndrome.

Six successive cases of congenital nephrotic syndrome are described. Each one showed flexion deformities of the knees and hips, widely open anterior and posterior fontanelles, and wide separation of the skull sutures. These abnormalities were present not only in cases in which the renal histology was of the microcystic Finnish type of congenital nephrotic syndrome, but also in those in which the histological picture was one of the variants associated with congenital nephrotic syndrome. It is suggested that such abnormalities are postural deformities, possibly produced by the large placenta.

Abnormalities, Multiple↗
PubMed1980

Tumors of the anterior uvea. I. Metastasizing malignant melanoma of the iris.

Although metastases from malignant melanomas of the ciliary body and choroid are common, similar tumors from the iris are rare. In this article seven such cases are described. They represent 3.5% of 196 cases in our files that were followed up for a minimum of five years where the tumor was confined to the iris and did not involve the ciliary body or the choroid. To our knowledge, this is the largest series to be described in the literature. Of the seven patients who died of metastases, six were male and autopsies were performed on four. There is evidence that diffusely infiltrating, heavily pigmented tumors, and tumors whose cell nuclei show prominent nucleoli are those most likely to metastasize.

Adolescent↗
PubMed1980

Tumours of the anterior uvea. III. Oxytalan fibres in the differential diagnosis of leiomyoma and malignant melanoma of the iris.

The diagnostic potential of oxytalan fibre demonstration in differentiating between leiomyomas and spindle-cell malignant melanomas of the iris was investigated. It was found that oxytalan fibres were abundant in leiomyomata, both between and around the tumour cells, whereas they were found in small numbers only and usually near the iris muscle in malignant melanomata. Their presence and distribution, therefore, appear to offer a satisfactory method of differentiating between these tumours. Since the human choroid and ciliary body normally contain oxytalan fibres, the above findings are not relevant to malignant melanoma of these structures. Naevi and regressing aggregates of iris melanoma cells away from the main tumour mass may similarly be surrounded by misleading amounts of these fibres.

Connective Tissue↗
PubMed1980

Tumours of the anterior uvea. II. Intranuclear cytoplasmic inclusions in malignant melanoma of the iris.

Intranuclear cytoplasmic inclusions have been described previously in both human and animal tissue. So far as we are aware they are described in detail for the first time in this paper in 60 cases of malignant melanoma of the iris, usually in spindle cells. The light microscopic appearances are described, and electron microscopic studies of selected cases show clearly the genesis of these inclusions by cytoplasmic invagination of the nuclear membrane. Their significance is discussed. It is of interest that we have seen identical inclusions in malignant melanomas of the ciliary body, choroid, and conjunctiva but have not as yet reported our findings.

Cell Nucleus↗