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Biomedical subjects

G Morgan

Publications and source records attributed to G Morgan.

At least 271 records · Page 15Linked to original sources
PubMed1987

First trimester diagnosis of adenosine deaminase deficiency.

Adenosine deaminase deficiency has been detected in the first trimester by direct analysis of enzyme activity in chorionic villi in a pregnancy at risk. Data for purine nucleoside phosphorylase activity in chorionic villi from healthy controls in the first trimester are also presented and should allow equally rapid diagnosis of this disorder.

Adenosine Deaminase↗
PubMed1987

Removal of a giant ovarian cyst. Anaesthetic and intensive care management.

Excision of a giant ovarian cyst may be associated with considerable mortality. Problems stem from the size of the cyst and the emaciated state of the patient. We describe a case in which the patient's pre-operative nutritional and psychological state required attention. Gradual pre-operative drainage of a cyst weighing 113 kg was carried out successfully. The main problems intra-operatively stemmed from copious blood loss and the duration of surgery. Postoperatively, ventilatory inadequacy occurred and was probably caused by altered mechanics of ventilation, postoperative pain and pulmonary oedema. We suggest ways in which the management of such cases might be improved.

Anesthesia, General↗
PubMed1987

A comparative study of T-cell depleted and non-depleted marrow transplantation for hematological malignancy.

Sixteen patients with hematological malignancy received cyclophosphamide (120 mg/kg), fractionated total body irradiation (12 Gy), oral cyclosporin, and an HLA-identical sibling marrow transplant depleted of T cells by incubation with the monoclonal antibody anti-HuLy-m1 (CD2) and rabbit complement with (five patients) or without (11 patients) anti-HuLy-m8). These 16 patients were compared historically to 84 patients with hematological malignancy receiving cyclophosphamide (120 mg/kg), fractionated total body irradiation (12 or 14 Gy), oral cyclosporin, and unmanipulated HLA-identical sibling marrow, for parameters of engraftment and graft-versus-host disease (GVHD). Graft failure occurred in one of the 16 T-cell depleted recipients and in one of the 84 nondepleted recipients. Engraftment was slightly but significantly slower in the T-cell depleted group and bacterial infections significantly more frequent and severe than in the unmanipulated group. There was a suggestion that the severity of acute GVHD was reduced in those receiving T depleted marrow. Randomized trials will be necessary to determine if marrow T-cell depletion results in superior long-term leukemia-free survival.

Acute Disease↗
PubMed1987

Central nervous system dysfunction and erythrocyte guanosine triphosphate depletion in purine nucleoside phosphorylase deficiency.

Developmental retardation was a prominent clinical feature in six infants from three kindreds deficient in the enzyme purine nucleoside phosphorylase (PNP) and was present before development of T cell immunodeficiency. Guanosine triphosphate (GTP) depletion was noted in the erythrocytes of all surviving homozygotes and was of equivalent magnitude to that found in the Lesch-Nyhan syndrome (complete hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency). The similarity between the neurological complications in both disorders indicates that the two major clinical consequences of complete PNP deficiency have differing aetiologies: neurological effects resulting from deficiency of the PNP enzyme products, which are the substrates for HGPRT, leading to functional deficiency of this enzyme. immunodeficiency caused by accumulation of the PNP enzyme substrates, one of which, deoxyguanosine, is toxic to T cells. These studies show the need to consider PNP deficiency (suggested by the finding of hypouricaemia) in patients with neurological dysfunction, as well as in T cell immunodeficiency. They suggest an important role for GTP in normal central nervous system function.

Central Nervous System↗
PubMed1987

Effects of a specific bradycardic agent (AQ-A39) and verapamil on beta-adrenergic responses in isolated guinea pig atria.

AQ-A39 (5,6-dimethoxy-2-[3-[(3,4-dimethoxy)phenylethyl)methylamino]propyl)- phthalimidine), a specific bradycardic agent, and verapamil, a calcium channel blocker, were studied for their ability to alter rate and force of contraction in the presence and absence of isoproterenol, a beta-adrenergic stimulant, using isolated guinea pig atria. Both compounds (10(-7)-10(-4) M) produced dose-related decreases in frequency of spontaneously beating right atria. Verapamil decreased, while AQ-A39 increased, the force of contraction of electrically stimulated (1.0 Hz) left atria. At equal negative chronotropic concentrations, AQ-A39 was more effective than verapamil in reducing the maximum isoproterenol-induced tachycardia. Verapamil, but not AQ-A39, antagonized positive inotropic responses to isoproterenol. Therefore, AQ-A39 differed from verapamil in that (i) AQ-A39 was a more selective bradycardic agent in both beta-adrenergically stimulated and nonstimulated preparations and (ii) AQ-A39 was more effective in reducing isoproterenol-elevated heart rate compared with basal heart rate. This profile of activities suggests that AQ-A39 will be beneficial in cardiac pathologies where sympathetic nervous system activity is elevated and a lowering of heart rate without a reduction in cardiac contractility is desired.

Animals↗
PubMed1987

Immunogold localization of placental lactogen and the SBU-3 antigen by cryoultramicrotomy at implantation in the sheep.

In the sheep, granulated trophectodermal binucleate cells (BNC) appear at implantation 16 days post coitum (dpc) and persist throughout pregnancy. Conventional immunocytochemical techniques at both light and electron microscope levels have indicated the presence of the ovine placental lactogen (oPL) hormone in the granules but no earlier than 22 dpc, when the level was very low. Immunofluorescent studies using glycolmethacrylate sections between 15 and 55 dpc suggest a completely different distribution of oPL restricted to uninucleate cells with none in the BNC. Using the most sensitive method available, immunocytochemistry on ultrathin frozen sections, the results in this paper demonstrate that BNC granules contain oPL at their earliest appearance (16-17 dpc). No significant localization was found in any uninucleate cell. In contrast, another molecule, the SBU-3 antigen, which is demonstrated in BNC granules later in pregnancy, is not present at the earliest stages but appears between 24 and 28 dpc coincident with the development of the foetal cotyledonary villi. The significance of these results for BNC function are discussed briefly.

Animals↗
PubMed1987

Heterogeneity of biochemical, clinical and immunological parameters in severe combined immunodeficiency due to adenosine deaminase deficiency.

There was considerable heterogeneity of the biochemical, clinical and immunological findings in 12 patients and two fetuses from 16 kindreds affected by severe combined immunodeficiency (SCID) due to a complete deficiency of the enzyme adenosine deaminase (ADA). Despite this heterogeneity a consistent pattern was observed, in which levels of abnormal purine metabolites paralleled the severity of the immunodeficiency. A high level of urinary deoxyadenosine was a universal finding for homozygous ADA deficiency. ATP depletion, in association with raised deoxy-ATP (dATP) levels, was found in the erythrocytes of nine infants with profound cellular and humoral immunodeficiency. There was no erythrocyte ATP depletion in two patients with some residual immunity, who presented later, but adenosine accumulated in their plasma and urine. This finding, together with the presence of some T and normal B-lymphocytes in less severely affected patients, suggests that adenosine is relatively non-toxic. The other results are consistent with the hypothesis that the sequence of deoxyadenosine accumulation, dATP formation and ATP depletion represents the major mechanism of toxicity to the immune system. Low numbers of T lymphocytes and dATP accumulation were also found in the blood of affected fetuses at 18 weeks gestation. Since extreme instability of erythrocyte ADA was demonstrated in some heterozygotes, and heterozygote ADA levels were detected in one infant with SCID, simultaneous immunological and biochemical analysis of fetal blood are important for precise antenatal diagnosis.

Adenosine Deaminase↗
PubMed1986

Bone-marrow transplantation for immunodeficiencies and osteopetrosis: European survey, 1968-1985.

In this retrospective analysis of allogeneic bone-marrow transplantation (BMT) carried out between 1969 and 1985 at fourteen European centres in 162 patients with sixteen different types of inherited immunodeficiencies and osteopetrosis, the overall survival with functional grafts was 51.7% (85 patients), with a minimum follow-up of 5 months. In patients with severe combined immunodeficiency HLA-matched (n = 41) and T-cell-depleted HLA-mismatched BMT (n = 46) resulted in 68% and 57% disease-free survival, respectively; after HLA-mismatched transplants, older age (greater than 6 months) and adenosine-deaminase deficiency resulted in poorer survival. Eight other lethal immunodeficiencies, including profound T-cell deficiencies, Wiskott-Aldrich syndrome, Kostmann syndrome, LFA-1/CR 3/p150,95 deficiency, and Chediak-Higashi syndrome as well as malignant osteopetrosis, have been successfully treated by BMT. In this group, survival with functional graft was 47% with HLA-matched and 29% with T-cell-depleted HLA-mismatched BMT. Engraftment failure was the major complication in this group. Poorer prognosis was associated with older patients, profound T-cell deficiencies, and the degree of HLA incompatibility.

Adolescent↗
PubMed1986

CD2 and CD3 antigens mobilize Ca2+ independently.

Antigen-induced stimulation of T cells is mediated via the CD3 antigen receptor (Ti) complex and monoclonal antibodies (mAb) reacting with CD3 and Ti result in rapid intracellular Ca2+ mobilization, followed by monocyte-dependent proliferation. Combinations of mAb to CD2, the sheep red blood cell receptor, also mobilize calcium and induce mitogenesis and purified phytohemagglutinin (PHA) stimulates T cells predominantly by interaction with this molecule. It has been suggested that activation via CD2 requires the presence of CD3 and that the hydrophobic epsilon chain of CD3 is the T cell calcium channel. To investigate this further we have obtained large numbers of natural killer (NK) cells which express CD2 but not CD3 from a patient with a chronic expansion of this lymphocyte subpopulation. It is shown that calcium mobilization can be induced in these cells by mAb to CD2 and purified PHA but not by anti-CD3 mAb. This indicates that calcium mobilization can be induced via the CD2 molecule in NK cells not expressing CD3 and that activation through CD2 is separate from the antigen receptor CD3 pathway.

Aminoquinolines↗
PubMed1986

Orthodontic movement of a canine into an adjoining extraction site.

The orthodontic movement of a canine tooth into an adjoining extraction site using a removable appliance is calculated using the finite element method (FEM). The calculated movements are compared, using a reflex plotter, with actual clinical measurements made on several patients. In both cases, wide variations in tooth displacement and hence rotation are found. The most important variable indicated by FEM appears to be the angle at which the load acts on the tooth. The position and magnitude of load have only a minor influence.

Cuspid↗
PubMed1986

Priming and the onset of neuromuscular blockade with alcuronium.

"Priming" with alcuronium has been studied in 72 female patients. Blockade of single twitch responses of the adductor pollicis by alcuronium 0.15, 0.2 or 0.3 mg kg-1 could be accelerated by priming with a suitable priming portion of the total dose. Giving alcuronium 0.04 mg kg-1 30 s after the induction of anaesthesia, followed by the balance 4 min later, resulted in more rapid neuromuscular blockade than giving the total dose at 4.5 min after induction. There was some suggestion of an increase in maximal twitch depression, but this could not be demonstrated confidently. The effect of increasing the priming portion was tested for the 0.3 mg kg-1 total dose, but any priming effect was attenuated. The mechanism of priming is not obvious. Occupation of "spare receptors" does not explain all of the features of priming.

Adult↗
PubMed1986

Successful haploidentical mismatched bone marrow transplantation in severe combined immunodeficiency: T cell removal using CAMPATH-I monoclonal antibody and E-rosetting.

Six patients with severe combined immunodeficiency were transplanted with bone marrow from their HLA haploidentical parents. T-lymphocytes were removed by complement mediated lysis with a monoclonal antibody (CAMPATH-I) followed by rosetting with sheep erythrocytes. The patients were pre-conditioned with marrow ablative chemotherapy, using busulphan and cyclophosphamide. There was graft take in five patients, with evidence of transient acute graft-versus-host disease only. Three patients are alive and well greater than 5 months after transplant, and one who is 12 months post graft has full reconstitution of cell mediated and humoral immunity, including specific antibody response to immunization. Transplantation across major histocompatibility barriers can be successfully achieved using this method of treatment of donor marrow.

Antibodies, Monoclonal↗
PubMed1986

Caring for the ill child in day care.

Current estimates indicate about 54% of American children have mothers who work outside the home. All children become ill, whether or not their parents are employed. However, for a working mother, even a mild illness can create anxiety, since alternate day care arrangements may be necessary. The problem of caring for the ill child in preschools or day care has received little attention from program planners or policy makers. Most state regulatory policies require exclusion of the ill child from day care. This article discusses recent developments in providing for ill children in day care settings. Four models of providing such care are described and criteria are offered for evaluating ill child care arrangements.

Child Day Care Centers↗