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Biomedical subjects

D R Cooper

Publications and source records attributed to D R Cooper.

At least 91 records · Page 5Linked to original sources
PubMed1987

Sertoli-cell prostaglandin synthesis. Effects of (follitropin) differentiation and dietary vitamin E.

The synthesis of prostanoids by the Sertoli cell was assessed as part of a study on the role of vitamin E in maintaining spermatogenesis. Analyses of eicosanoid synthesis from endogenous substrate were carried out using freshly isolated Sertoli-cell-enriched preparations from both pre-pubertal and adult rats fed purified diets with and without vitamin E, as well as cells carried in primary culture. Freshly isolated cells from both the immature and fully differentiated adult testes produced PGI2 (prostaglandin I2) and PGE2, but PGF2 alpha was produced only by cells of the adult vitamin E-deficient rat. Cells from adult controls synthesized PGF2 alpha after primary culture. In contrast with other hormone responses of this cell, which are refractory in the adult, FSH (follitropin) potentiated prostaglandin production by freshly isolated cells of both immature and adult rats. The FSH response of Sertoli cells from immature animals did not change after primary culture. Adult cells were refractory to the hormone after culture, but the total amounts of prostaglandins produced by these cells were 10-fold higher than by either freshly isolated or cells of the immature in culture. Analogues of cyclic AMP did not potentiate prostaglandin synthesis. However, mepacrine, a phospholipase inhibitor, blocked the FSH effect. The finding that Sertoli cells synthesize prostaglandins and FSH enhances prostaglandin production implicates a potential role for eicosanoids in spermatogenesis and suggests that vitamin E may affect intratesticular regulators.

Age Factors↗
PubMed1987

L-dopa esters as potential prodrugs: behavioural activity in experimental models of Parkinson's disease.

Intraperitoneal administration of the 2-tetrahydropyranylmethyl, phenoxyethyl, ethyl, 2-hydroxypropyl and methyl ester prodrugs of L-dopa produced locomotor activity in reserpine-pretreated mice with equal intensity and duration to that observed following administration of L-dopa itself. Administration of the 2-(1-methoxy)propyl ester produced a more prolonged effect while the p-methoxyphenylethyl, n-propyl, phenylethyl, m-trifluoromethylbenzyl, cyclohexyl, p-chlorophenylethyl and benzyl ester prodrugs were less active than L-dopa itself. On oral administration, the ethyl and methyl ester prodrugs were more effective than L-dopa in reversing reserpine-induced akinesia in mice. The 2-tetrahydropyranylmethyl, 2-(1-methoxy)propyl, 2-hydroxypropyl, n-propyl, benzyl and phenoxyethyl ester prodrugs produced effects comparable with those of L-dopa. In contrast, the cyclohexyl, m-trifluoromethylbenzyl, phenylethyl, p-chlorophenylethyl and p-methoxyphenylethyl ester prodrugs were less effective than L-dopa on oral administration. Intraperitoneal administration of L-dopa and the ester prodrugs of L-dopa to rats with a prior 6-hydroxydopamine (6-OHDA) lesion of the medial forebrain bundle (MFB) produced contraversive circling responses. Rotation observed following administration of the n-propyl, 2-tetrahydropyranylmethyl, methyl and ethyl ester prodrugs was more intense than that observed following administration of L-dopa itself. Rotation produced by the administration of L-dopa and the cyclohexyl, 2-(1-methoxy)propyl, phenylethyl, p-chlorophenylethyl, p-methoxyphenylethyl, benzyl, 2-hydroxypropyl, phenoxyethyl and m-trifluoromethylbenzyl ester prodrugs was identical. Ester prodrugs of L-dopa may be as effective as L-dopa itself in producing motor activity but overall none of the compounds tested was markedly more potent or of longer duration than L-dopa itself.

Animals↗
PubMed1987

L-dopa esters as potential prodrugs: effect on brain concentration of dopamine metabolites in reserpinized mice.

The intraperitoneal administration of L-dopa and a series of ester prodrugs of L-dopa to reserpinized mice produced elevations of striatal and tuberculum olfactorium homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) levels. Differences in the pattern of change produced by individual drugs, compared with L-dopa, were observed. Only the phenoxyethyl ester caused elevations of both striatal and tuberculum olfactorium HVA and DOPAC, greater than those measured following L-dopa administration. Overall the m-trifluoromethylbenzyl, phenylethyl, p-chlorophenylethyl and p-methoxyphenylethyl ester prodrugs produced greater elevations of striatal and tuberculum olfactorium HVA, but not DOPAC, compared with L-dopa. The administration of the 2-tetrahydropyranyl-methyl derivative only enhanced striatal HVA and striatal and tuberculum olfactorium DOPAC concentrations. Changes of HVA and DOPAC tissue concentrations following administration of the 2-hydroxypropyl, n-propyl, methyl, ethyl and 2-(1-methoxy)propyl ester prodrugs were comparable with those produced by the administration of L-dopa itself. The alterations in striatal and tuberculum olfactorium HVA and DOPAC levels observed did not correlate with the ability of these compounds to elicit locomotor activity in reserpinized mice.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Effect of vitamin E deficiency on serum concentrations of follicle-stimulating hormone and testosterone during testicular maturation and degeneration.

Although vitamin E has been recognized as a requirement for normal testicular function for more than 50 yr, the functional role of this fat soluble vitamin in the maintenance of spermatogenesis has not been clarified. Vitamin E deficiency has a deleterious effect on germ cell proliferation and differentiation in the rat and a variety of other animal species. The potential effect of vitamin E on the sensitivity of the hypothalmo-hypophyseal-gonadal feedback system has not been previously evaluated. Therefore, serum testosterone concentrations, androgen function in maintaining seminal vesicle weight, and citrate synthesis, as well as the circulating amounts of FSH, were determined in rats fed semipurified diets with vitamin E, control, and without vitamin E, vitamin E-deficient. To assess dietary effects before, during, and after testicular degeneration, analyses were carried out on animals fed the diets starting at 3 weeks of age and continuing for 1 yr. The defect produced by vitamin E deficiency does not reflect impaired gonadotropin function. There are no effects of vitamin E deprivation on either serum levels of testosterone or on seminal vesicle weight and citrate content suggesting that the LH-testosterone feedback loop is not impaired. The feedback loop of FSH and inhibin also appears to be normal. Serum FSH concentrations are not elevated, although the testis is germ cell depleted. Comparison of the vitamin E-deficient model to other models of testicular degeneration suggests that the effect of vitamin E occurs directly or indirectly on the regulation of intratesticular factors which regulate specific steps of germ cell development.

Animals↗
PubMed1987

Multivariate statistical analysis of L-dopa esters as potential anti-parkinsonian prodrugs.

This paper reports a QSAR study of thirteen L-DOPA esters previously synthesised and examined for their physicochemical, biochemical and behavioural properties. Multivariate statistical analysis (principal component analysis, cluster analysis, simple and multiple linear regression) reveals favourable and unfavourable structural features of L-DOPA prodrugs. Some of the many biochemical and behavioural activities investigated are shown to be redundant. These indications may contribute to the design of novel L-DOPA prodrugs.

Analysis of Variance↗
PubMed1986

Haemolytic disease associated with Leptospira interrogans serovar pomona in red deer calves (Cervus elaphus).

Three red deer calves (Cervus elaphus) died with a haemolytic disease associated with infection by Leptospira interrogans serovar pomona. Infection within the herd was more prevalent than disease. Sera from 16 herd mates were tested by the microscopic agglutination test (MAT) and 12 had leptospiral titres, the majority to serovar pomona. A few calves had titres to balcunica and hardjo. Urine was obtained for culture from six of these calves and serovar pomona was isolated from five with titres to pomona, and hardjo from one with a titre to hardjo but not pomona. A fourth calf died with severe nephritis but a diagnosis of leptospirosis was not confirmed in this case.

Journal Article↗
PubMed1986

Further evidence implicating diacylglycerol generation and protein kinase C activation in agonist-induced increases in glucose uptake. Insulin-like effects of phenylephrine in BC3H-1 myocytes.

We have previously suggested that insulin effects on 2-deoxyglucose (2-DOG) uptake in BC3H-1 myocytes are due to increases in de novo phospholipid synthesis, diacylglycerol generation, and protein kinase C activation. To test this hypothesis further, we examined the effects of phenylephrine, an agonist that increases diacylglycerol and protein kinase C activity through phospholipase C activation. As evidence for phospholipase activation in BC3H-1 myocytes, we found that phenylephrine increased acute 32PO4 incorporation into phosphatidic acid and phosphatidylinositol, generation of [3H]inositol phosphates from prelabeled [3H]inositol phospholipids, cytosolic Ca2+, and membrane-bound protein kinase C. Phenylephrine also provoked dose-related increases in [3H]2-DOG uptake that were similar in magnitude and time course to those induced by insulin. As with insulin, phenylephrine effects on 2-DOG uptake were not apparent in myocytes that were maximally stimulated with 12-O-tetradecanoylphorbol-13-acetate, a diacylglycerol analogue that activates protein kinase C. These findings support our hypothesis that diacylglycerol generation and protein kinase C activation may be important in the stimulation of glucose uptake by agents such as phenylephrine and insulin that activate the phosphoinositide cycle.

Animals↗
PubMed1986

Aortic dissection in adolescence.

Although aortic dissection is rare in children, it does occur, particularly in those with congenital heart disease, connective tissue disorders or severe trauma. Prompt diagnosis is essential. Aortic dissection should be considered in children and adolescents with severe abdominal pain, especially pain that migrates. The patient is often much more uncomfortable than can be explained on the basis of physical findings. Criteria have been established for choosing medical or surgical therapy.

Abdomen↗
PubMed1984

Behavioural and biochemical alterations in the function of dopamine receptors following repeated administration of L-DOPA to rats.

Rats received L-DOPA (40 or 200 mg/kg, i.p.) for 14 days, followed by a 3 day withdrawal period. Spontaneous locomotor activity was not altered by repeated administration of L-DOPA. Rats treated with L-DOPA (200 mg/kg) showed identical locomotor hypoactivity in response to small doses of apomorphine when compared to saline-treated control animals. However, hyperactivity induced by large doses of apomorphine was reduced by prior treatment with L-DOPA (200 mg/kg). The smaller dose of L-DOPA (40 mg/kg) did not alter the locomotion induced by apomorphine. Stereotyped behaviour induced by apomorphine was enhanced by prior treatment with both 40 and 200 mg/kg of L-DOPA. The treatment regimes with L-DOPA had no effect on the concentrations of apomorphine in the striatum. Administration of L-DOPA (40 or 200 mg/kg) followed by withdrawal for 3 days, had no effect on the concentrations of dopamine, homovanillic acid (HVA) or 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum. The Bmax and KD for the binding of [3H]spiperone, [3H]N,n-propylnorapomorphine (NPA) and [3H] piflutixol in the striatum was not altered by drug treatment. Similarly, the formation of dopamine-stimulated cyclic AMP in homogenates of striatum was unaltered by repeated administration of L-DOPA. Repeated administration of L-DOPA for 14 days in the rat appears to result in altered behaviour mediated by dopamine in the absence of any apparent change in the function of dopamine receptors in the striatum.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1984

L-Dopa methyl ester--a candidate for chronic systemic delivery of L-Dopa in Parkinson's disease.

Continuous intravenous infusions of L-Dopa as a treatment for response swings in Parkinson's disease are limited by the insolubility and acidity of L-Dopa. Its methyl ester is a soluble neutral derivative that might be of benefit to these patients, and is examined in the present study in behavioural and biochemical animal models. On intraperitoneal or subcutaneous administration to mice L-Dopa methyl ester was equivalent to L-Dopa in reversing reserpine-induced akinesia and producing contraversive circling behaviour in rats with a 6-hydroxydopamine lesion of the medial forebrain bundle. On oral administration the methyl ester was more active. The administration of L-Dopa or the methyl ester produced equivalent changes in striatal and mesolimbic dopamine, homovanillic acid, and 3,4-dihydroxyphenylacetic acid metabolite levels. We suggest that systemic or subcutaneous infusion of L-Dopa methyl ester to patients who experience response fluctuations may provide a means of maintaining mobility.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1984

Adsorption of plasma from tumor-bearing hosts over protein A--containing nonviable Staphylococcus aureus Cowan I: possible mechanism of antitumor reactions.

Adsorption of autologous plasma over nonviable Staphylococcus aureus Cowan I (SAC) followed by reinfusion of the plasma causes regression of (a) chemically induced rat mammary adenocarcinomas (MA), and (b) canine transmissible venereal tumors (TVT) and spontaneously occurring dog tumors. Animal data are more impressive than that from trials in humans. Nine of 41 patients receiving perfusions of adsorbed plasma showed some partial objective response. Eight of these nine patients received multiple perfusions over a period of time. Twenty-one of 41 patients showed subjective responses. Adsorption of autologous plasma over non-protein A--containing S. aureus Wood 46 caused regression of MA. Adsorption of normal rat plasma with SAC, and infusion of this adsorbed plasma into mammary tumor--bearing rats, caused regression of MA. Intravenous infusion of purified protein A alone caused regression of both rat MA and canine TVT. Superimposed on this observation is the finding that, during plasma adsorption, bacterial moieties leach from SAC. It is possible that the immunostimulation observed in plasma-perfused hosts is due to the removal of plasma blocking agents on one hand, and introduction of the bacterial agents on the other.

Adenocarcinoma↗
PubMed1982

Extracorporeal immunoadsorption of plasma from a metastatic colon carcinoma patient by protein A-containing nonviable Staphylococcus aureus: clinical, biochemical, serologic, and histologic evaluation of the patient's response.

A patient with a metastatic colon carcinoma was treated by immunoadsorption (IA) therapy using heat-killed, formalin-stabilized protein A-containing Staphylococcus aureus Cowan I as the immunoadsorbent. The patient experienced both subjective and objective positive clinical response without undue morbidity. The patient's response correlated well with laboratory findings of decreased concentrations of carcinoembryonic antigen (CEA), immunoglobulin G (IgG), immune complexes (IC) and histopathologic data. The patient underwent surgery following 15 IA treatments; she lived for eighteen months, post-treatment.

Adenocarcinoma↗
PubMed1982

Radical mastectomy: thick vs thin skin flaps.

Radical mastectomy with wide skin excision, ultrathin skin flaps, and autogenous skin grafts was a selected treatment of 45 women with curable breast cancer. A similar group of 45 women were treated by radical mastectomy with less wide skin excision, primary wound closure, and without ultrathin skin flaps. The two patient series were comparable in clinical disease staging, age, axillary node metastases, and frequency of adjunctive chest-wall irradiation. Retrospective chart reviews of the two patient series and statistical analyses indicated that five-and ten-year survival and local recurrences were comparable, but wound complications, hospital stays, and subsequent lymphedema were significantly greater in the series with thinner skin flaps. We recommend that routine use of ultrathin flaps be abandoned for treatment of breast cancer.

Breast Neoplasms↗
PubMed1981

Specific immunoadsorption of IgG antibody in a patient with chronic lymphocytic leukemia and autoimmune hemolytic anemia. A new form of therapy for the acute critical stage.

Progressive and severe autoimmune hemolytic anemia developed in a patient with chronic lymphocytic leukemia (CLL) despite treatment with chlorambucil, high doses of corticosteroids and attempts to transfuse packed red blood cells. Splenectomy was not performed because of severe coronary artery disease. Direct antiglobulin tests revealed a warm red blood cell autoantibody of IgG-type with anti-e specificity. The patient was treated by extracorporeal immunoadsorption of plasma IgG using a cell separator and protein A as the immunoadsorbent. The patient responded by an increase in the hemoglobin levels and platelet counts after two treatments. Specificity of the procedure was shown by a decrease in the serum IgG and by the demonstration of the same reactivity to ficin-treated reagent red blood cell panel of the eluate from the protein A. Antibody titers of the patient's red blood cell eluate decreased from 1:128 to 1:64 and eventually the anti-e specificity was lost. This is a report of a novel approach to treatment of the acute phase of an autoimmune hemolytic anemia.

Adsorption↗
PubMed1980

Efficient removal of abnormal immunoglobulin G from plasma of a multiple myeloma patient. Description of a new method for treatment of the hyperviscosity syndrome.

Patients with multiple myeloma who have complications secondary to hyperviscosity are treated by chemotherapy and/or plasmapheresis. Because the response to chemotherapy is usually delayed, plasmapheresis is required for the removal of larger concentrations of plasma proteins to avoid life-threatening complications. Until now there has been no available means to decrease the abnormal plasma proteins in a selective manner. This report describes a new method for the selective removal of immunoglobulin G from the plasma of a patient suffering from IgG-type multiple myeloma. Results obtained from plasmapheresis and selective immunoadsorption of IgG are compared. It appears that the technique described herein may offer a new, more efficient method for the palliative treatment of diseases associated with elevated concentrations of plasma immunoglobulin G.

Adult↗
PubMed1980

Extracorporeal immunoadsorption of myeloma IgG and autoimmune antibodies: a clinically feasible modality of treatment.

Using heat-killed, formalin-stabilized Staphylococcus aureus Cowan I suspension, it was possible to remove myeloma IgG and autoimmune anti-red blood cell antibodies from two patients' plasma following an extracorporeal procedure. The arterial anticoagulated blood was processed through a cell separator machine. The separated plasma was pumped through a bacterial filter containing S. aureus suspension. The adsorbed plasma was then reunited with the blood cells and returned to the patient through the vein. S. aureus Cowan I could selectively remove the myeloma IgG and autoimmune anti-red cell antibodies from the patients' plasma prolonging the lives of these two terminal patients. The immunoadsorption procedure appears to be a safe, practical and quick method for the removal of pathological IgG from the patients' plasma.

Adult↗