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Biomedical subjects

E Young

Publications and source records attributed to E Young.

At least 199 records · Page 11Linked to original sources
PubMed1985

Aboriginal socio-economic characteristics: issues affecting the interpretation of statistics.

Statistical data on aborigines in Australia are examined, and it is recognized that internationally accepted census definitions and criteria may not be appropriate for analyzing the situation of aboriginal groups. In particular, the author "uses 1981 census-based comparisons of some Aboriginal and non-Aboriginal socio-economic characteristics and discusses how these assessments are affected by Aboriginal attributes. Attention is confined to three commonly used socio-economic indicators: labour force status, occupational category and income (on an individual and per capita basis)--all examined on an Australia-wide basis and specifically for the Northern Territory."

Australia↗
PubMed1985

Changes in releasability of ACTH and beta-endorphin with chronic stress.

The activation of the hypothalamic pituitary adrenal axis by stress is well-known. Using inescapable intermittent footshock as a stressor in rats, we have previously demonstrated a rise in circulating plasma Beta-endorphin/Beta-LPH which parallels the rise in plasma ACTH, the primary POMC derived peptides released by anterior lobe. In addition, the rise in ACTH is accompanied by approximately a tenfold rise in plasma corticosteroids. Short term anterior lobe pituitary cultures from rats who have received inescapable intermittent footshock for 30 minutes show a blunted dose response curves to the ACTH releasing secretagogues arginine vasopressin (AVP) and ovine corticotropin releasing factor (oCRF). Similarly a blunted dose response curves to secretagogues can be seen by either the addition of dexamethasone (0.5 nM) to the culture medium or pretreatment of the rats with 1 mg dexamethasone intraperitoneally 90 minutes prior to decapitation. Thus, glucocorticoids may play a role in the blunted response to secretagogues seen in anterior lobe cultures from acutely stressed rats. We now report that chronically stressed rats exhibit increased releasability of ACTH and Beta-endorphin/Beta-LPH products by oCRF, suggesting an increase of the peptides in the releasable pool.

Adrenocorticotropic Hormone↗
PubMed1985

Immunology of corneal allograft rejection. Associated human leucocyte populations.

Human serum samples and peripheral blood mononuclear leucocytes (PBML) were collected from ten corneal transplant recipients over a two-year period at intervals before and after surgery, and during and after episodes of immunologic (rejection) reaction. Serum was monitored for the development of antibodies to histocompatibility antigens and PBML were stained with a panel of monoclonal reagents specific for T cell and for monocyte populations using indirect immunofluorescence. Patients who demonstrated an elevation in the Leu 2a+ (suppressor/cytotoxic) T cell population following an immunologic reaction ultimately accepted their grafts, whereas patients whose Leu 2a+ population was unaffected developed irreversible graft clouding. Additionally, a direct positive correlation between the development of elevated levels of lymphocytotoxic antibodies and helper T cells was noted in some patients during immunologic reactions. Neither DR-positive nor monocyte population changes demonstrated any consistent correlation with rejection episodes or final graft outcome.

Adult↗
PubMed1985

Corneal alpha-galactosidase deficiency in macular corneal dystrophy.

Glycosidases, which cleave sugar molecules from complex glycopolymers, have been previously quantified in normal human cornea in our laboratory. Data quantifying glycosidases in macular corneal dystrophy are lacking. Tissue obtained at keratoplasty from patients with macular dystrophy and normal corneas obtained from eye bank eyes were used to determine levels of glycosidase activity. A fluorometric technique was employed using 4-methyl-umbelliferyl-glycosides as substrates. The corneal tissues were homogenized, centrifuged, and the supernatants assayed for enzyme activity. Specific activities (mumol/mg protein/hour) were determined and Km and Vmax values were obtained for all but one enzyme. Activity of alpha-galactosidase was significantly lower in cornea tissue and keratocytes from macular corneal dystrophy compared to normal.

Cornea↗
PubMed1985

Delayed type hypersensitivity in atopic dermatitis.

Three different aspects of delayed type hypersensitivity in atopic dermatitis (A.D.) were studied. (a) Intradermal testing demonstrated that positive reactions to bacterial vaccines were distinctly lower in patients with A.D. (b) Patch testing in patients with A.D. compared to tests in patients with anal eczema showed a striking difference in results concerning the substances to which positive reactions were found. (c) Patients with A.D. (n = 18), atopics without A.D. (n = 10), patients with contact dermatitis (n = 10), and normal controls (n = 10), were patch tested with various human dander (H.D.) fractions after stripping the stratum corneum with skin tape. Only patients with A.D. showed positive reactions, the maximum response being at 24-48 hours. There was no difference in reaction pattern between partially purified H.D. subfractions. Histopathological examination revealed an eczema-reaction. Patch testing within the same patient groups with purified house dust mite allergen P1 demonstrated similar results. Although this finding argues against a specific role of H.D. allergen in A.D. it may at least be concluded that H.D. preparations have the capacity to provoke immediate as well as delayed type skin reactions.

Adolescent↗
PubMed1985

Immunology of corneal allograft rejection: in vitro sensitization of effector cells.

Anterior chamber injection of donor rabbit lymphocytes sensitized in vitro to recipient alloantigens leads to the development of small focal areas of endothelial cell destruction (pocks) on the recipient cornea. Damage may be observed through a specular microscope as early as 2 days after injection of sensitized lymphocytes. Recipients of unsensitized allogeneic or sensitized autologous lymphocytes demonstrate little or no endothelial damage and no pock formation. Flat endothelial preparations reveal focal destruction of the endothelium with multiple foci, many infiltrated and surrounded by mononuclear cells. This model provides controlled sensitization to a variety of histocompatibility and corneal antigens that may be responsible for initiation of graft rejection.

Animals↗
PubMed1985

Immunology of corneal allograft rejection: HLA-DR antigens on human corneal cells.

Human stromal and endothelial cultures were established from corneas obtained from the Maryland Eye Bank. Cultures were incubated in the presence of human gamma interferon for 4 days, trypsinized, washed, and then stained with a monoclonal reagent specific for human Class II (HLA-DR) antigens. Under these conditions, 100% of human corneal endothelial cells and 40 to 70% human corneal stromal cells expressed HLA-DR antigens.

Cornea↗
PubMed1984

Hemodynamic effects of intravenous amiodarone.

Amiodarone is a potent antiarrhythmic agent that is effective in controlling both atrial and ventricular arrhythmias. Recently, intravenous administration was demonstrated to be effective in the acute management of rhythm disorders and, in addition, appeared to shorten the loading period normally required for oral drug administration. This investigation examined the hemodynamic effects of amiodarone after both acute intravenous bolus and continuous intravenous administration. Patients with a left ventricular ejection fraction greater than 0.35 experienced improved cardiac performance due to both acute and chronic peripheral vasodilation. However, patients with a lower ejection fraction developed a 20% decrease in cardiac index and clinically significant elevation of right heart pressures after acute bolus administration; these changes were variably compensated for by peripheral vasodilation when the drug was administered intravenously over 3 to 5 days continuously. Therefore, intravenous amiodarone can result in significant impairment of left ventricular performance in patients with preexisting left ventricular dysfunction.

Amiodarone↗
PubMed1984

Immune mechanisms in chlamydial eye infection: cellular immune responses in chronic and acute disease.

The current studies detail cell-mediated immune responses to Chlamydia trachomatis antigen in both acute and chronically infected monkeys. Peripheral blood mononuclear leukocytes (PBMLs) from three groups of animals (immunized before infection, not immunized before infection, and chronically infected) were tested for the capacity to proliferate in response to C. trachomatis antigen in vitro. Only those animals that had been systemically immunized before acute ocular infection responded significantly. Coculturing macrophages from nonresponding animals with T cells from D-histocompatible responding animals showed that the ability to present antigen was unaffected in nonresponding animals. These studies also demonstrated that removal of suppressor T cells from PBMLs before culture resulted in increased proliferation in the chronically infected group and suggested that the nonresponsiveness seen in chronic ocular disease may be mediated by suppressor T cells.

Acute Disease↗
PubMed1984

Awake abnormalities of control of breathing and of the upper airway. Occurrence in healthy older men with nocturnal disordered breathing.

We hypothesized that preexisting diminished chemical control of breathing and narrowing of the upper airway are associated with sleep-related disordered breathing (SRDB) in healthy older men. Twenty-six subjects, aged 55 to 70, were studied. An SRDB episode was a decrease in arterial oxygen saturation (SaO2) of at least 4 percent. Some of these episodes occurred while airflow continued (ie, nonapneic episodes), and the rest occurred with apnea. Sixteen subjects had greater than 12 SRDB episodes per hour of sleep (SRDB subjects) and ten subjects had less than 8 episodes per hour (controls). During waking, the mean hypercapnic ventilatory response was lower, and the mean supine nasal airway resistance (SNAR) was higher in SRDB subjects than in control subjects. During waking, 12 of 16 SRDB subjects had one or more respiratory abnormalities: four had an elevated SNAR; four had a reduced hypercapnic response; three had a reduced hypoxic ventilatory response, and two had an abnormal flow-volume curve. Only one of ten control subjects had a respiratory abnormality (an elevated SNAR). Also, the number of SRDB episodes per hour correlated with the SNAR, and the minimum SaO2 during sleep correlated with the magnitude of the hypercapnic response. We conclude that SRDB occurs commonly in otherwise healthy older men with preexisting abnormalities of control of breathing or of the upper airway.

Age Factors↗
PubMed1983

[3H] dynorphin binding to guinea pig and rat brain.

[3H] Dynorphin can be shown to bind to the brains of both rat and guinea pigs with approximately 50% specific binding. Characterization of the binding in terms of multiple opiate receptor types supports the kappa selectivity of dynorphin in guinea pig. However, in rat brain, a substantial proportion of the [3H] dynorphin binding is displaced by morphine, suggesting a mu as well as kappa component. Consequently, in rat, dynorphin may show effects at both mu and kappa receptors in vivo.

Animals↗
PubMed1983

Transplantation antigens and keratoplasty.

Allograft rejection is one of the leading causes of corneal graft failure in man when the cornea is heavily vascularised. This paper reports the feasibility and possible benefits of using histocompatibility (HLA) antigen crossmatch testing and HLA-D locus antigen matching for corneal donor selection. Double-masked clinical trials designed to determine the value of these procedures for keratoplasty are discussed.

Adolescent↗
PubMed1983

Selective alterations of opiate receptor subtypes in monosodium glutamate-treated rats.

Neonatal treatment of rats with monosodium glutamate (MSG) has been demonstrated to destroy cell bodies of neurons in the arcuate nucleus including the brain beta-endorphin (B-END) system. The effects on opiate receptors of the loss of B-END is unknown. Neonatal rats were treated with MSG as previously described. After reaching maturity (7-9 months), MSG-treated rats and litter-matched untreated control rats were decapitated and brains dissected into brain regions. Opiate receptor assays were run with [3H]morphine (mu receptor ligand) and [3H]D-alanine2-D-leucine5 (DADL) enkephalin (delta receptor ligand) for each brain region for both MSG and control rats simultaneously. Scatchard plot analyses showed a selective increase in delta receptors in the thalamus only. No corresponding change in mu receptors in the thalamus was found. The cross-competition IC50 data supported this conclusion, showing a loss in the potency of morphine in displacing [3H]DADL enkephalin in the thalamus of MSG-treated rats. This shift in delta receptors produced an IC50 displacement pattern in thalamus, ordinarily a mu-rich area, similar to that of striatum or cortex, delta-rich areas, again indicating an increase in delta receptors. Similar changes in delta receptors in other brain regions were not found. These results represent one of the few examples of a selective and localized shift in delta with no change in mu sites. Furthermore, the delta increase may reflect an up-regulation of the receptors in thalamus after chronic loss of the endogenous opioid B-END.

Animals↗