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Biomedical subjects

B Morris

Publications and source records attributed to B Morris.

At least 91 records · Page 5Linked to original sources
PubMed1984

Interspecific chimerism--the characterization and immunological responsiveness of Bos taurus-Bos indicus haemopoietic chimeras produced by embryo transfer.

Bos taurus-Bos indicus twin calves were produced by embryo transfer and their degree of haemopoietic chimerism and immune responsiveness examined. All 10 pairs of Friesian-Brahman twins were chimeric compared with only 6 out of 12 pairs of Jersey-Brahman twins. In the Friesian-Brahman twins, Friesian lymphocytes predominated in all calves while in the Jersey-Brahman twins there was no uniform dominance of one cell type over another. All calves that had chimeric lymphocyte populations were also erythrocyte chimeras, although in two pairs of twins the genotype of the erythrocytes was different from the genotype of the lymphocytes. The lymphocytes of all chimeric calves failed to respond in mixed lymphocyte culture (MLC) tests to the lymphocytes of their co-twins but gave vigorous responses to cells from other calves. Primary and secondary immune responses to keyhole limpet haemocyanin (KLH) antigen were studied in the efferent prefemoral lymph in normal Jersey, Friesian and Brahman calves, in 1 set of Jersey-Brahman twins and in 5 sets of Friesian-Brahman twins. The immune responses of chimeric twins with genetically identical lymphocyte populations were quite dissimilar and were characteristic of the somatic genotype of the calf and not of the genotype of the lymphocyte population. The chimeric status of the cell population in the lymph did not change significantly during the response. These results suggest that either the genetic capacity of a population of lymphocytes to recognize and respond to antigens can be modified during ontogeny in an alien genetic environment or that a crucial determinant of the final outcome of an immune response is not the immunocompetent cell itself but the physiological and anatomical environment in which it exists.

Animals↗
PubMed1984

The measurement of the oxygen tension of lymph in conscious sheep.

A method is described for continuously measuring the PO2 of lymph in conscious sheep. An indwelling polarographic electrode inserted into a plastic cannula has been used to measure the PO2 in efferent popliteal lymph close to the point at which the lymph leaves the node. The mean PO2 of popliteal lymph in normal sheep was found to be 46.6 +/- 5.3 mm Hg, equivalent to 7.1 +/- 0.8% O2. Following antigenic challenge with killed Salmonella bacteria, the PO2 of the lymph changed significantly. These changes were related to the cellular response in the lymph and in the node. The PO2 values were maximum in the lymph 8 h after the injection of antigen during the 'shut-down' period and minimum at around 80 h when the blast cell response was at its height. These in vivo findings suggest that in vitro studies on sheep lymphocytes should be done with gas mixtures containing 7% O2.

Animals↗
PubMed1984

The respiration and energy metabolism of sheep lymphocytes.

The respiration characteristics and energy metabolism of sheep lymphocytes collected from the popliteal lymph before and after antigenic challenge with Salmonella organisms have been studied at various O2 tensions. The O2 consumption of sheep lymphocytes could be related to the PO2 of the medium by the Michaelis-Menten equation. In resting lymphocytes, Vmax (mean +/- S.D.) was 1.70 +/- 0.23 mumoles/h/2 X 10(8) cells), critical O2 concentration [( O2]crit) was 2.00 +/- 0.20 microM and Km was 0.46 +/- 0.11 microM. Significant changes occurred in the respiration characteristics of these cells following antigenic challenge of the node. Both Vmax and Km reached maxima when the blast cell response in the lymph was at its peak. [O2]crit, however, did not change significantly over an immune response. Lymphocytes collected before antigenic challenge had mean rates of glucose uptake of 0.97 +/- 0.29 mumoles/h/2 X 10(8) cells and lactate production of 1.31 +/- 0.37 mumoles/h/2 X 10(8) cells. During the height of immune responses to Salmonella, lymphocytes showed an enhanced glucose uptake, lactate production and C-1- and C-6-labelled glucose metabolism. The rates of energy metabolism of sheep lymphocytes varied with changes in the PO2 of the gas phase from 21% to 0% O2. The rates of glucose uptake and lactate production increased while the rates of 14CO2 production from C-1- and C-6-labelled glucose decreased as the PO2 decreased.

Animals↗
PubMed1984

Effects of clonidine and xylazine on body temperature in the rat.

Clonidine and xylazine injected intraperitoneally both produced a dose-dependent hypothermia in unanaesthetized, freely moving rats. The alpha 2-antagonist yohimbine produced an antagonism of the xylazine-induced hypothermia but a potentiation of the clonidine-induced hypothermia. The opioid antagonist naloxone had little effect on the xylazine hypothermia, but potentiated the clonidine hypothermia. It is concluded that whilst the two alpha 2-agonists produce a similar hypothermic effect in the rat, they are acting by different mechanisms.

Animals↗
PubMed1984

Kinetic studies on IgG transport by the jejunum of the neonatal rat.

A 0.2-ml dose containing 500 micrograms labelled rat IgG saturated the receptor-mediated transport system of the enterocytes of the jejunum of the small intestine. At subsaturation dose levels very little intracellular digestion of IgG occurred--the intact transport system was primarily employed. The uptake of IgG by enterocytes, at doses above saturation, was assessed over periods up to 6 h. There was an initial phase of rapid intracellular digestion by the enterocytes, followed by a much longer period during which the receptor-mediated transport system discharged intact IgG into the vascular compartment. The observations are discussed in the light of recent evidence relating to the numbers of IgG receptors on jejunal enterocytes.

Animals↗
PubMed1983

Protein binding to brush borders of enterocytes from the jejunum of the neonatal rat.

The specific binding of IgG to jejunal brush borders was greatest at acidic pH, at neutral pH no specific binding occurred. Specific binding declined with age-no specific binding occurred in borders from 20-and 24-day-old animals. There was no specific binding of IgG to borders from ileal enterocytes. Human transferrin and bovine serum albumin did not bind specifically to borders. The affinity of binding (-Ka) and the receptors site numbers per border estimated for rat IgG were 18.64 X 10(6) M-1 to 3.53 X 10(6) sites; for human IgG, 25.06 X 10(6) M-1 to 3.30 X 10(6) sites; for bovine IgG, 10.48 X 10(6) M-1 to 2.11 X 10(6) sites and for sheep IgG, 7.26 X 10(6) M-1 to 2.34 X 10(6) sites.

Animals↗
PubMed1983

The evolution and involution of Peyer's patches in fetal and postnatal sheep.

The Peyer's patches (PP) of sheep have a number of important anatomical features and functional characteristics which are similar to tissues that have been classified as primary lymphoid organs. The prenatal maturation of PP occurs in the absence of any antigenic stimulus as immunogenic molecules are not normally encountered by the sheep fetus. Primordial PP were first detected in the small intestine of fetal sheep at about 60-days gestation; lymphoid follicles were present by 75-days gestation and vigorous lymphopoiesis was occurring in these follicles by 100 days. From 120-days gestation until birth, at about 150 days, the PP follicles were histologically mature and they had the greatest density of proliferating lymphoid cells found anywhere in the body. The total number of PP and their constituent follicles had developed before birth when there were 25-40 discrete PP in the jejunum and proximal ileum and one single continuous PP in the terminal ileum. There was no evidence of any change in the rate of growth of the PP follicles at birth which could be related to the advent of the first antigens in the gut. The total weight of PP tissue was greater than any other single lymphoid tissue by about 6 weeks after birth weighing around 120 g or about 1.2% of the body weight; about 50-60 g of the PP tissue was calculated to be lymphoid tissue. At this time the ileocecal PP (IPP) extended 2.5 m along the terminal ileum and accounted for about 90% of the total mass of PP. From about 12 weeks after birth the IPP began to involute and only a few PP follicles remained in this region of the intestine by 18 months of age. Follicles in PP in other parts of the small intestine remained and continued to produce lymphocytes throughout the life of the animal. PP contain a number of anatomically and functionally distinct lymphoid compartments that could play different roles in the body's immune defense. Explicit in most theories on the function of PP is the notion that antigenic stimulation is the cause of the lymphopoiesis in the follicles; our results do not support this view. Instead they suggest that the follicles in the PP of sheep may play a role similar to that played by the bursa of Fabricius in birds.

Animals↗
PubMed1983

Hormone-releasing stimuli do not alter Met-enkephalin levels in the rat neurohypophysis.

The levels of met-enkephalin in the rat neurohypophysis were measured by radioimmunoassay in four groups of animals. The groups were a control untreated group, a sham operated group, a group subjected to 1% body weight haemorrhage which is an acute hormone releasing stimulus, and a group subjected to four days 2% saline imbibition which is a chronic hormone releasing stimulus. In none of the groups was the met-enkephalin level significantly different from the control value of 1.90 +/- 0.18 ng/gland (n = 10), suggesting that there was no depletion of met-enkephalin concomitant with the depletion of neurohypophysial hormones in the rat.

Animals↗
PubMed1983

Recent developments in the care, treatment, and rehabilitation of the chronic mentally ill in Britain.

Just as the deinstitutionalization movement has swept the United States in recent years, the effort to provide alternatives to public hospitals has been government policy in Britain for the past 20 years. While problems remain, Britain, which reduced its mental hospital census less than America, has had some success in finding proper community treatment and care for its former hospital patients, especially the chronically disabled. The author describes recent developments in the administration and organization of services for chronic patients and in clinical practice. The effects of new legislation and several government reports on community care are outlined, as are two new experiments in finding community housing for former hospital patients. Developments in biological psychiatry, use of depot neuroleptic therapy, electroconvulsive therapy, and industrial therapy are also briefly mentioned.

Chronic Disease↗
PubMed1983

The binding of proteins to isolated enterocytes from the small intestine of the neonatal rat.

IgG binds specifically to isolated jejunal enterocytes but not to ileal enterocytes; maximum binding occurred at pH 6. The ability of jejunal enterocytes to bind IgG was reduced to low levels at 20 days of age and was lost at 24 days. Human and rat IgG were bound specifically in similar amounts; human IgG displaced rat IgG with identical efficiency to rat IgG (ED50 = 50 nM). Much less bovine and sheep IgG were bound to enterocytes and the ED50s for these proteins were 150 nM and 2.5 microM, respectively. Rat IgG bound to jejunal enterocytes with high affinity (13.21 x 10(6)M-1) and to 4.83 x 10(6) sites per cell. Receptor protein was estimated to represent 0.18% of total cell protein. These observations are discussed in relation to the results of in vivo IgG transmission studies. It is estimated that the IgG transport mechanism, operating at maximum efficiency, requires that available IgG receptors would come into use once to twice per hour.

Aging↗
PubMed1983

The influence of gut function on lymphoid cell populations in the intestinal mucosa of lambs.

The number and type of lymphoid cells in the intestinal mucosa of lambs change during the first weeks after birth. The influence of gut function on these changes was examined by comparing the evolution of lymphoid cell populations in normal ileum with that in lengths of ileum which had been isolated surgically from the functional intestinal tract of the lamb before birth. The isolated lengths of ileum had a normal blood and nerve supply and they remained healthy throughout a period of at least 2 years, although they did not have a normal histological development. In comparison with normal ileum, the villi of the isolated ileal segments were much smaller and there were many fewer intraepithelial lymphocytes; the lamina propria had significantly fewer lymphocytes than the functional ileum and only a few plasma cells. When isolated ileal segments were reconnected into the intestinal tract after having been isolated from it for 1-3 months, the histology of the mucosa reverted to that of the normal gut, with the same number and types of lymphoid cells. Radiolabelled lymphoblasts collected from intestinal lymph and injected intravenously accumulated to only a small extent in isolated segments of ileum compared with either the normal or the reconnected segments of ileum. This suggested that the paucity of lymphocytes in the mucosa of the isolated segments was due to a reduced extravasation of these cells there. The influence which the gut contents exert on the lymphoid cell population in the mucosa is probably associated with antigenic stimulation but may also be related to other factors concerned in the normal digestive functions of the gut.

Animals↗
PubMed1982

The accumulation and intracellular compartmentation of cadmium, lead, zinc and calcium in two earthworm species (Dendrobaena rubida and Lumbricus rubellus) living in highly contaminated soil.

The earthworm Lumbricus rubellus contained more Ca and Zn, and less Pb and Cd, than Dendrobaena rubida living in the same contaminated disused-mine soil. Differences in the kinetics of Ca turnover may account for some of the inter-specific differences in heavy metal burdens, although the calciferous glands do not seem to be directly involved in heavy metal excretion. A comparison of the present findings with published data indicated that the concentration of soil Ca and the bioavailability of heavy metals, both factors being allied to soil pH, are important exogenous determinants of heavy metal accumulation by different earthworm populations. Electron microprobe X-ray analysis of air-dried smears of chloragogenous tissue showed that the metals were fairly specifically compartmentalized into two distinct organelles in both worms: Ca, Pb and Zn were found (associated with P) in the chloragosomes; Cd was found (with S and probably in stoichiometric association) in a more electron-lucent vesicular component, designated the 'cadmosome', but which may be identical with the debris vesicles which are characteristic inclusions in conventionally-fixed chloragocytes. The in vivo incorporation of Pb by the chloragosomes of D. rubida was accompanied by the loss of Ca, Zn and P.

Animals↗
PubMed1982

Interactions of drugs active at opiate receptors and drugs active at alpha 2-receptors on various test systems.

1 The actions of the opiate receptor drugs, morphine, methionine-enkephalin (Met-enkephalin) and naloxone were compared with the actions of the alpha 2-receptor drugs, clonidine, xylazine and yohimbine on analgesic tests, in vitro bioassay (guinea-pig ileum and mouse vas deferens), and radioligand displacement studies on rat brain membrane preparations. 2. Both opiate and alpha 2-agonist drugs showed analgesic activity but whilst the alpha 2-agonist analgesic activity was antagonized by only alpha 2-antagonists, the analgesic activity of morphine was antagonized by both naloxone and yohimbine. In the in vitro tests, both groups of agonists inhibited electrically evoked activity; however in these experiments only antagonism of opiates by naloxone and alpha 2-agonists by yohimbine could be shown and it is concluded that in these systems the activity of the alpha 2-agonists is mediated via the presynaptic alpha 2-receptors only. 3 In the radioligand studies the drugs acting at alpha 2-receptors were active in the micromolar range at displacing labelled opioid ligands but opiates did not displace labelled alpha 2-ligands. 4 It is concluded that drugs which act on alpha 2-receptors interfere with the in vivo analgesic effects of opiates and weakly displace opioid radioligand binding, but opioids do not affect alpha 2 agonist analgesia and do not appear to displace alpha 2-agonist radioligand binding.

Adrenergic alpha-Agonists↗
PubMed1981

The uptake and transmission of protein by neonatal rat enterocytes.

1. Proximal enterocytes transmitted intact immunoglobulin G (IgG) preferentially in the order rat, human, sheep and bovine; the removal from the vascular compartment of these transmitted molecules occurred at about the same rate. 2. Heterologous IgGs are processed similarly to rat IgG: they are either transmitted intact or broken down to less than 1000 mol. wt. fragments. 3. All of the human transferrin removed from the intestine was broken down to less than 1000 mol. wt. fragments, but a small amount of bovine serum albumin (BSA) was transmitted intact. 4. The IgGs and BSA are relatively indigestible molecules whereas human transferrin is relatively digestible. 5. These observations are discussed in the context of receptor-mediated transmission.

Animals↗
PubMed1981

Effect of adrenalectomy on the transmission of IgG in young rats.

Antibody transmission in rats aged 17 days was unaffected by adrenalectomy performed at 13 days. The normal 'closure' of the jejunum to antibody is delayed by about 2 days in adrenalectomised rats. Adrenalectomy at 13 days has no apparent effect on plasma volume or haematocrit. Plasma corticosterone levels increase fivefold between 14 and 20 days, but in early weaned animals with 'closed' guts, corticosterone levels were not raised.

Adrenalectomy↗
PubMed1980

Reassortment of cell populations within the lymphoid apparatus of the sheep.

As lymphocytes recirculate through the blood tissues and lymph they are sorted into populations which have varying morphological and functional characteristics. Lymphocytes are added, deleted and transformed within the lymphoid apparatus as a consequence of non-random migration and antigenic stimulation. There is evidence that the physiological characteristics of peripheral and central lymph nodes vary as a result of differences in the origins of the cells entering the nodes. Lymphocytes enter the lymph nodes from the blood and lymph in varying numbers; consequently the cell population in the efferent lymph of central and peripheral lymyph nodes contains different proportions of blood-borne and lymph-borne cells. Cells arriving in lymph nodes by way of the blood or the lymph migrate differently within the node. Those entering from the blood go principally to the paracortex and the follicular areas. Lymphocytes entering in the lymph are distributed through both the cortex and the medulla. In humoral antibody responses and in the response that occurs during the rejection of a renal allograft, lymph-borne cells populate the medullary cords, cortex and germinal centres of the nodes they enter. Within these nodes, new populations of cells are generated which have different functional attributes from the cells which provoked their formation.

Animals↗
PubMed1980

A genetic influence on the appearance of specific antibody in serum and secretions following challenge with antigen.

The concentration of specific antibody in the tear secretion following subconjunctival inoculation with Keyhole Limpet haemocyanin was influenced by genotype. Cattle of the Bos indicus type responded more strongly to subconjunctival inoculation than did Bos taurus animals. The regression analysis of the concentration of specific antibody in tears on the concentration of specific antibody in the serum suggested a quantitative difference in the transfer of specific antibody from the serum to tears. The concentration of specific antibody in serum was different in Bos indicus and Bos taurus animals. The relative position of this difference was influenced by the route of inoculation used.

Animals↗