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Biomedical subjects

R Morris

Publications and source records attributed to R Morris.

At least 415 records · Page 23Linked to original sources
PubMed1976

Changes in the ultrastructure of the gills of the river lamprey, Lampetra fluviatilis (L.), during the anadromous spawning migration.

Two types of mitochondria-rich cells were found in the interplatelet areas of the gills of the migrating river lamprey. Both cell types are thought to be responsible for ion-transport across the gills. In the fresh-run migrant the gills are dominated by large, flask-shaped cells which show some ultrastructural similarities with the teleost chloride cell and have been tentatively referred to as ion-excretory cells. During the spawning migration the ion-excretory cells are replaced by smaller, mitochondria-rich cells which are similar in structure to the presumed ion-transporting cells in the ammocoete gill. They lack the tubular, smooth-membraned endoplasmic reticulum so characteristic of the lamprey ion-excretory cell and the teleost chloride cell and have been referred to as ion-uptake cells. The ion-uptake cells are found during the stenohaline, freshwater phases of the lamprey's life history. Ion-excretory cells are present during the periods of the life cycle when the animal is euryhaline. The possibility that the ion-excretory cells are also responsible for ion-uptake in fresh water is discussed.

Animals↗
PubMed1976

Fine structure of the interplatelet area in the gills of the macrophthalmia stage of the river lamprey, Lampetra fluviatilis (L.).

The interplatelet epithelium of the gills of freshwater and seawater adapted macrophthalmia stages of the river lamprey, Lampetra fluviatilis, was studied by electron microscopy. Three main cell types: basal, ion-excretory and superficial cells were identified and described. Ion-excretory cells were exposed to the environment in sea water but covered by a layer of superficial cells in fresh water. Electron-dense secretory granules in the apex of the cell were more abundant in fresh water. In fresh water, a few of the superficial cells contained numerous mitochondria and were identified as ion-uptake cells. In view of the scarcity of ion-uptake cells, the possibility that the ion-excretory cells are also responsible for ion-uptake in fresh water is discussed. Phagocytic removal of degenerating ion-excretory cells may be an important mechanism for the conservation of materials in a starving animal.

Animals↗
PubMed1976

A simple method for counting antibody bound labelled steroids.

A simple method is described for the counting of tritiated antibody-bound steroid after acidification and extraction into a toluene based scintillant. The resulting count rate is stable and quenching is minimal. The method give improved count rates when compared with methods employing scintillants containing methanol, dioxane, or Triton and compares favourably with methods involving pre-heating of antibody-bound steroid or extraction of free steroids after the addition of ammonium sulphate. A specific antibody for estradiol has been used to illustrate the application of the technique to antibody titration curves and standard curves.

Animals↗
PubMed1976

The effects of corticosterone and cortisone on the uptake of polyvinyl pyrrolidone and the transmission of immunoglobulin G by the small intestine in young rats.

1. The distribution of polyvinyl pyrrolidone along the intestinal lumen and in the intestinal wall, following oral administration to normal and corticosterone treated rats, was found to be extremely variable. Valid comparisons between the two groups of animals could not be made using this technique. 2. Three, 4 and 5 days after corticosterone treatment there was no significant change in the uptake of 125I-labelled polyvinyl pyrrolidone from standard doses injected into ligated segments of the distal small intestine; nor did the treatment induce precocious replacement of the absorptive cells in this region. Cortisone induced precocious cell replacement, a process which took up to 4 days to complete, and also led to a marked reduction in the uptake of 125I-labelled polyvinyl pyrrolidone from ligated segments of the distal intestine. 3. Three days after treatment with corticosterone (5 mg I.P. at 12 days) there was a marked reduction of labelled immunoglobulin G transport into the blood. Four and 5 days after treatment there was some recovery of the immunoglobulin G transport function. Three days after treatment with cortisone (5 mg I.P. at 12 days) there was closure of the gut to labelled immunoglobulin G. 4. The relevance of these results to antibody transmission and the termination of immunoglobulin transport is discussed.

Animals↗
PubMed1976

Quantitative assessment of the transmission of labelled protein by the proximal and distal regions of the small intestine of young rats.

1. The plasma volume in rats aged 15-16 days was measured by dilution analysis using homologous, 125I-labelled immunoglobulin G. A mean plasma volume of 5-53 ml./100 g and a mean blood volume of 8-01 ml./100 g were obtained.2. After the injection of labelled immunoglobulin G into the heart, homogenates of various abdominal organs and of the carcass were prepared. Labelled immunoglobulin G left the vascular compartment at a rate of about 9-10%/hr over a 3 hr period. About 11% of the labelled immunoglobulin G was catabolized in 2 hr. 3. The data obtained from these studies was used to make quantitative estimates of the amount of intact immunoglobulin G transmitted from the proximal intestine and from the ileum after the intra-intestinal injection of 1000 mug of labelled immunoglobulin G. Homogenates of the experimental animals were prepared and it was estimated that over 40% of the labelled immunoglobulin G was transmitted as intact protein from the proximal intestine. The results suggest that no intact immunoglobulin G was transmitted from the ileum, but about 15% of the protein removed from the ileum was recovered in the whole body as degraded fragments precipitable with trichloroacetic acid. 4. These observations are discussed in the context of the transmission of antibodies, and their relevance to the receptor hypothesis is considered.

Animals↗
PubMed1976

Immunodeficiency in the chicken. IV. An immunological study of infectious bursal disease.

Chickens inoculated orally with infectious bursal disease virus (IBDV) 1 day after hatching subsequently showed a 50% incidence of immunodeficiency but little mortality. Antibody responses against IBDV and to immunization with sheep red blood cells (SRBC) or human serum albumin (HSA) were suppressed. Serum IgG concentration was decreased while IgM occurred exclusively in its 7S monomeric form (mIgM). An allotypic marker of chicken IgM (Mla) was lacking in mIgM derived from IBDV-infected birds. The loss of Mla occurred gradually in several birds between 3 and 12 weeks after perinatal infection. Inoculation of IBDV into chickens 3 weeks after hatching resulted in 50% mortality level but little immunodeficiency. Paradoxically, the serum IgG concentration was elevated, in comparison with normal birds. Histology of the bursa showed permanent hypo- or aplasia of follicles irrespective of the age of infection. The results suggest that bursal but not peripheral B cells are targets for IBDV, and immunodeficiency results from impaired peripheral seeding of B cells in infected juvenile chickens.

Age Factors↗
PubMed1975

Ultrastructure of the presumed ion-transporting cells in the gills of ammocoete lampreys, Lampetra fluviatilis (L.) and Lampetra planeri (Bloch).

Mitochondria-rich cells were located in the interplatelet area of gill filaments from ammocoete Lampetra fluviatilis and L. planeri. The ultrastructure of this cell type differs from typical teleost 'chloride cells' by the absence of a tubular, smooth endoplasmic reticulum (SER). This difference is discussed in relation to the presumed functions of the cell and to the evolutionary histories of lampreys and teleosts. It is concluded that the mitochondria-rich cell is responsible for the active uptake of ions by the ammocoete gill.

Animals↗
PubMed1975

Assay of cortisol in serum by competitive protein binding without solvent extraction.

A method for the determination of serum cortisol by competitive protein binding is proposed in which solvent extraction is replaced by heat inactivation. Results obtained by the new technique correlate well with those obtained by solvent extraction. A saving in manipulative time and glassware is effected when the method is applied in a routine assay.

Animals↗
PubMed1975

Gonadotrophic stimulation of oestrogen synthesis by cultured immature mouse ovaries.

The amount of oestrogen produced by immature mouse ovaries cultured with purified gonadotrophins was measured by means of a radioimmunoassay. Small quantities were released in response to FSH or LH alone, but when both were provided production was greatly enhanced after an initial lag phase of 2-3 days. The lowest concentrations required to produce this synergistic effect were between 0-02 and 0-13 i.u. FSH/ml and between 0-01 and 0-1 i.u. LH/ml. After prolonged exposure to 0-4 i.u. FSH/ml plus 1-0 i.u. LH/ml, oestrogen output continued to rise until, on the ninth day of culture, it reached 2-6-7-3 ng/ovary/day. Pre-treatment with 0-4 i.u. FSH/ml for 3 days enhanced the subsequent response to combined gonadotrophins but the simultaneous presence of FSH and LH was essential for inducing the delayed synergistic effect. Although both gonadotropins also stimulated follicle growth there was no evidence suggesting any simple correlation between that response and oestrogen synthesis. Maximal oestrogen production coincided with very low follicular mitotic activity.

Animals↗