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Biomedical subjects

A Moran

Publications and source records attributed to A Moran.

At least 91 records · Page 5Linked to original sources

Severe endocrine and nonendocrine manifestations of the McCune-Albright syndrome associated with activating mutations of stimulatory G protein GS.

McCune-Albright syndrome (MCAS) is a sporadic disease classically including polyostotic fibrous dysplasia, café au lait spots, sexual precocity, and other hyperfunctional endocrinopathies. An activating missense mutation in the gene for the alpha subunit of GS, the G protein that stimulates cyclic adenosine monophosphate formation, has been reported to be present in these patients. The mutation is found in variable abundance in different affected endocrine and nonendocrine tissues, consistent with the mosaic distribution of abnormal cells generated by a somatic cell mutation early in embryogenesis. We describe three patients with MCAS who had profound endocrine and nonendocrine disease and who died in childhood. Two of the patients were severely ill neonates whose complex symptoms did not immediately suggest MCAS. A mutation of residue Arg201 of GS alpha was found in affected tissues from all three children. A review of the literature and unpublished case histories emphasizes the existence of other patients with severe and unusual clinical manifestations. We conclude that the manifestations of MCAS are more extensive than is generally appreciated, and may include hepatobiliary disease, cardiac disease, other nonendocrine abnormalities, and sudden or premature death.

Adolescent↗

Florid vascular proliferation in repeated intussusception mimicking primary angiomatous lesion.

A case of recurrent intussusception in a 76 year old man associated with vascular proliferation is reported. The initial biopsy specimen showed that ulceration and inflammation were not features. The proliferation was so florid as to point to an angiomatous lesion. At this stage a diagnosis of intussusception was not considered. The clinical impression was that of a caecal mass associated with a filling defect visible on barium enema and a fleshy "suspicious" lesion on colonoscopy. This case illustrates the possibility of misinterpreting the importance of florid vascular proliferation in biopsy material where other features indicative of a reparative process are absent.

Aged↗

Lymphocyte transformation responses to phytohaemagglutinin and pokeweed mitogen in patients at differing stages of HIV infection: are they worth measuring?

AIMS: To determine whether the routine measurement of lymphocyte transformation responses to mitogenic stimuli provide any information additional to that available from routine T cell CD4 and CD8 analysis in patients with HIV infection. METHODS: The case records of 197 immunologically investigated HIV seropositive patients were reviewed. The influence of disease stage on T lymphocyte subsets and lymphocyte transformation responses (LyTR) to phytohaemagglutinin (PHA) and Pokeweed mitogen was assessed. RESULTS: The median CD3 and CD4 counts and LyTR to PHA and Pokeweed mitogen were highest in patients with persistent generalised lymphadenopathy (PGL) and decreased progressively in the order: asymptomatic patients, those with ARC, those with AIDS. LyTR to PHA was preserved in over 70% of all patients, but the response to Pokeweed mitogen was depressed in 8% of patients with PGL, 34% of asymptomatic patients, 68% of those with ARC and 78% of those with AIDS. Subnormal values of both CD4 + T cells and LyTR to Pokeweed mitogen were more common in patients with ARC and AIDS (68%) than in those who were asymptomatic or had PGL (20%). CONCLUSIONS: CD4 T cell analysis and LyTR to Pokeweed mitogen, but not to PHA, both correlate with disease states in patients with HIV infection.

AIDS-Related Complex↗

Secretagogue-induced RVD in HSY cells is due to K+ channels activated by Ca2+ and protein kinase C.

To maintain cell volume, absorptive epithelia must coordinate ion fluxes associated with transcellular transport with those required for volume regulation. K+ channels are thought to play a central regulatory role in this process. Electronic cell sizing was used to study the regulatory volume decrease (RVD) response of the human salivary ductal cell line HSY. Following a hypotonic challenge, RVD was markedly enhanced by the muscarinic agonist carbachol (half-maximal effect approximately 1.4 microM). Carbachol-induced RVD was mimicked by the K+ ionophore valinomycin and inhibited by K+ channel blockers, indicating that it is due to the activation of K+ channels. Carbachol-induced RVD was blocked by maneuvers that blunted the carbachol-induced rise in intracellular Ca2+ concentration ([Ca2+]i) and mimicked by ionomycin-induced increases in [Ca2+]i, but concentrations of ionomycin (100 nM) yielding [Ca2+]i well above carbachol-induced levels were required. However, when treatment with 2.5 nM ionomycin, which produced [Ca2+]i in the carbachol-generated range, was combined with treatment with low concentrations of an active phorbol ester, an enhancement of RVD similar to that observed with carbachol alone was observed. These data provide strong evidence that carbachol-induced RVD in the HSY cells involves K+ channels that are tightly regulated by both [Ca2+]i and protein kinase C.

Atropine↗

PGE2 inhibits Na-K-ATPase activity and ouabain binding in MDCK cells.

In the present study we report on a direct effect of prostaglandin E2 (PGE2) on ouabain binding and Na-K-adenosinetriphosphatase (Na-K-ATPase) activity in a clone of Madin-Darby canine kidney cells, a renal cell line with collecting duct properties. Incubation of the cells with low concentrations (pM) of PGE2 produced a concomitant reduction of approximately 50% in the activity of Na-K-ATPase in the cell homogenate and in ouabain binding to the intact cells (half-maximal inhibition of approximately 0.1 pM). The inhibition was apparent within 10 min of preincubation of the cells with PGE2. Scatchard analysis of the binding demonstrated that the treatment with PGE2 reduced the number of ouabain binding sites without a change in the dissociation constant. PGE1 and PGF2 alpha (10 nM) did not affect ouabain binding or Na-K-ATPase activity. The fast, potent, and specific effect of PGE2 suggests that the diuretic/natriuretic effect of prostaglandins of the E series in the collecting tubule, in addition to the interference with the activity of arginine vasopressin, may result from a direct reduction in the number of the Na-K-ATPase active units, via a prostaglandin receptor.

Animals↗

Cystine loading induces Fanconi's syndrome in rats: in vivo and vesicle studies.

To better understand the link between lysosomal cystine accumulation and the renal impairment seen in cystinosis, we have studied the effect of cystine loading in vivo, on renal function of rats, and in brush-border membrane vesicles (BBMV) prepared from the kidney cortex of the treated rats. Intraperitoneal injection of cystine dimethyl ester (CDME) (400 mumol, twice a day, for 5 days) led to an increased urine volume and excretion of glucose, phosphate, and protein. Kinetic analysis of alpha-methylglucoside initial flux in BBMV showed reduction in maximal transport capacity (Vmax, from 10.1 +/- 1.3 to 8.5 +/- 0.7 nmol.min-1.mg protein-1; P < 0.01) with no change in Michaelis constant (Km, 4.80 +/- 0.08 and 4.90 +/- 0.05 mM). The number of phlorizin binding sites declined (from 6.5 +/- 0.7 to 4.1 +/- 0.4 pmol/mg protein; P < 0.01) with no significant change in the affinity for phlorizin (0.64 +/- 0.08 and 0.59 +/- 0.06 microM). In the cortex homogenate, cystine concentration, which was undetectable in controls, increased to 0.97 +/- 0.09 nmol 1/2 cystine/mg protein. Two hours after CDME administration, ATP content declined to approximately 50% of control values. This decline was transient, and ATP content was recovered to control values 5 h after CDME administration. The treatment did not affect ouabain-sensitive adenosinetriphosphatase activity (40.0 +/- 3.9 and 38.6 +/- 4.7 nmol Pi.mg protein-1.min-1) or the number and affinity of ouabain binding sites (Bmax = 1.48 +/- 0.25 and 1.44 +/- 0.18 pmol/mg, and Kd = 0.68 +/- 0.09 and 0.72 +/- 0.12 microM, respectively). (ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

Detection of colorectal cancer by faecal alpha 1-antitrypsin.

Alpha 1-antitrypsin was measured in 5-day faecal collections from patients with colorectal cancer or adenomatous polyps and a symptomatic control group. Collections were homogenized and lyophilized prior to measurement of alpha 1-antitrypsin by radial immuno-diffusion. Colorectal cancer dry weight concentrations were significantly higher than the symptomatic control results, with 57% having results greater than 95% normal values of this control group. There was no significant difference between adenomatous polyp dry weight concentrations and symptomatic control results. Wet weight concentrations were calculated from wet/dry ratios. Colorectal cancer wet weight concentrations were significantly higher than symptomatic control results with 48% having results greater than 95% normal values of this control group. Alpha 1-antitrypsin was also measured in non-lyophilized samples from an asymptomatic control group (n = 39). Colorectal cancer wet weight concentrations were significantly higher than asymptomatic control results, with 62% having results greater than 95% normal values of this control group. Faecal alpha 1-antitrypsin measurement deserves further assessment for use in detecting colorectal cancer.

Adenoma↗

Effects of quinpirole on autonomic nervous control of heart rate in rats.

The effects of quinpirole, a specific dopamine DA2 receptor agonist, on autonomic nervous control of heart rate, were studied in normotensive pithed rats, by analysing its action on the tachycardia and bradycardia evoked by electrical stimulation of the cardioaccelerator (10 V; 1 ms; 0.5, 1, 3, 6 Hz) and vagus (10 V; 1 ms; 3, 6, 9 Hz) nerves respectively. Quinpirole (10-50-100 micrograms kg-1 iv) reduced the cardioacceleration elicited by electrical stimulation but not that by noradrenaline (3 micrograms kg-1 iv). The effect on electrical stimulation was blocked by domperidone (0.5 mg kg-1 iv) but not by SCH 23390 (0.2 mg kg-1 iv) or idazoxan (0.3 mg kg-1 iv). At 1, 5, 10, 30 micrograms kg-1 iv, quinpirole decreased vagal but not acetylcholine-induced bradycardia. The effect on electrical stimulation was inhibited by domperidone (0.5 mg kg-1 iv) but not by SCH 23390 (0.2 mg kg-1 iv), prazosin (0.1 mg kg-1 iv) or idazoxan (0.3 mg kg-1 iv). The data point to the presence of presynaptic and/or ganglionic dopamine receptors in the sympathetic and parasympathetic innervation of the rat heart, where stimulation inhibits the release of neuromediators.

Animals↗

Effect of quinpirole on neurogenic vasoconstriction in the in situ autoperfused hindquarters and renal vascular beds of the rat.

1. The effects of local administration of quinpirole were studied in the in situ autoperfused hindquarters and renal vascular beds, in order to assess whether presynaptic dopamine receptors in these vascular systems could play a role in the hypotensive effect of this agonist. 2. In both preparations, local injection of quinpirole did not alter perfusion pressure, but reduced the pressor response to electrical stimulation of the sympathetic innervation. Increases in perfusion induced by local administration of noradrenaline were not altered by quinpirole. 3. The inhibitory effect of quinpirole on the stimulation-evoked pressor responses was completely antagonized by intravenous administration of the DA2-receptor antagonist domperidone (0.5 mg kg-1) but not by the DA1-receptor antagonist SCH 23390 (0.3 mg kg-1) or the alpha 2-adrenoceptor antagonist idazoxan (0.3 mg kg-1). 4. The results indicate that quinpirole inhibits neurally induced pressor responses in the autoperfused hindquarters and renal vascular beds of the rat by stimulation of presynaptic dopamine receptors. These receptors may be involved in the hypotensive action of quinpirole in the rat.

Adrenergic alpha-Antagonists↗

Cystine dimethyl ester reduces the forces driving sodium-dependent transport in LLC-PK1 cells.

Cystinosis is an inherited metabolic disease characterized by accumulation of lysosomal cystine and renal impairment. In an attempt to better understand the link between cystine accumulation and renal functions, we studied the effects of cystine loading on the Na(+)-H+ antiporter and the sodium pump in renal epithelial cells (LLC-PK1) in culture. Incubation of LLC-PK1 with 1 mM cystine dimethyl ester (CDME) for 48 h caused lysosomal cystine loading and reduced by 22 +/- 2% the maximal velocity of sodium-hydrogen antiport with no significant change in the affinity of sodium for the transporter. Rubidium influx decreased to 46 +/- 5% of control. Ouabain binding experiments revealed a 10% reduction in the number of Na(+)-K(+)-ATPase units in the intact cells. Na(+)-K(+)-ATPase activity in the particulate fraction of the cells homogenate declined to 50 +/- 7.5% of controls. No significant change was observed in the activity of ouabain-insensitive phosphatases. The intracellular concentration of sodium increased from 20.6 +/- 3.7 to 64.8 +/- 10 mM, and potassium concentration decreased from 103 +/- 6 to 80 +/- 13 mM. In addition to the observed reduction in the sodium gradient and in agreement with the reduction in the intracellular potassium concentration, the membrane potential changed from -80.8 +/- 7.5 to -69.9 +/- 7.0 mV. The results suggest that intracellular accumulation of cystine is associated with reduction in the number and the activity of membrane transporters. The consequence of the changes in the activity of Na(+)-K(+)-ATPase is a reduction in the electrochemical forces that drive transport in the renal cells tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Burkitt's lymphoma in adults: a retrospective study of 46 cases.

The prognosis of Burkitt's lymphoma is generally considered to be poor, particularly in the advanced stages of the disease. Although recent chemotherapy protocols have given high rates of cure in children, there are few such reports concerning adults. We therefore conducted a retrospective analysis of the results for treatment of 46 adults in the Institut Gustave Roussy (IGR) between 1978 and 1987, in order to establish an effective treatment strategy for use in a prospective trial. The median age of the patients was 31 years and the majority were Caucasians of European origin. The clinical symptoms and course of the disease were similar to those in the pediatric situation and corresponded to the so-called non endemic forms observed in Europe and the United States. Presentation was generally extra-nodal, usually with abdominal manifestations. As a rule, the disease progressed rapidly and showed a high affinity for the central nervous system in the absence of specific prophylaxis, despite systemic therapy with highly active agents, particularly in the advanced stages. According to Murphy's classification, there were 6 stage I, 11 stage II, 19 stage III and 10 stage IV patients (3 of whom had CNS involvement). Treatment was heterogenous, although all the patients received polychemotherapy including anthracyclins. The best results were obtained from eleven patients treated according to the French Multicenter Protocols for pediatric Burkitt's lymphoma (LMB-84 and LMB-86). Kaplan-Meier 5-year relapse free survival rate among the 46 patients was 42% (stage I: 83%; stage II: 67%; stage III: 30%; stage IV: 30%). In order to standardize our therapeutic approach, we started a prospective study in 1988 using the unmodified pediatric protocol for our adult patients.

Adolescent↗

Pharmacological characterization of dopamine receptors in parasympathetic innervation of rat heart.

The action of dopamine agonists (apomorphine, bromocriptine, pergolide and quinpirole) on the bradycardia induced in vivo by electrical stimulation of the vagus nerves was studied in pithed rats pretreated with atenolol. The dopamine agonists decreased significantly the vagal-induced but not the acetylcholine-induced bradycardia. The first effect was blocked by (S)-sulpiride or domperidone but not by yohimbine, prazosin or SCH 23390. Both effects were antagonized by methylatropine. The data suggest the presence of presynaptic and/or ganglionic dopamine DA2 receptors in the parasympathetic innervation of the rat heart, stimulation of which inhibits the release of acetylcholine.

Acetylcholine↗

Pancreatic endocrine function in cystic fibrosis.

To characterize pancreatic endocrine secretion and to examine interrelationships among alterations in alpha, beta, and pancreatic polypeptide cell function in patients with cystic fibrosis (CF), we studied 19 patients with exocrine insufficiency (EXO), including 9 receiving insulin therapy (EXO-IT); 10 patients with no exocrine insufficiency (NEXO); and 10 normal control subjects. First-phase C-peptide response to intravenously administered glucose was significantly impaired in CF patients with exocrine insufficiency (EXO-IT = 0.02 +/- 0.01; EXO = 0.11 +/- 0.02; NEXO = 0.25 +/- 0.05; control subjects = 0.30 +/- 0.04 nmol/L). Lowering fasting glucose levels with exogenous insulin administration in EXO-IT did not improve beta cell responsivity to glucose. The C-peptide response to arginine was less impaired (EXO-IT = 0.12 +/- 0.02; EXO = 0.15 +/- 0.02; NEXO = 0.23 +/- 0.06; control subjects = 0.28 +/- 0.04 nmol/L). Alpha cell function, measured as peak glucagon secretion in response to hypoglycemia, was diminished in EXO but not NEXO (EXO-IT = 21 +/- 10; EXO = 62 +/- 19; NEXO = 123 +/- 29; control subjects = 109 +/- 12 ng/L). Despite diminished glucagon response, EXO patients recovered normally from hypoglycemia. Peak pancreatic polypeptide response to hypoglycemia distinguished CF patients with exocrine insufficiency from those without exocrine insufficiency (EXO-IT = 3 +/- 2; EXO = 3 +/- 1; NEXO = 226 +/- 68; control subjects = 273 +/- 100 pmol/L). Thus CF patients with exocrine disease have less alpha, beta, and pancreatic polypeptide cell function than CF patients without exocrine disease. These data suggest either that exocrine disease causes endocrine dysfunction in CF or that a common pathogenic process simultaneously and independently impairs exocrine and endocrine function.

Adult↗