Improvement of postreceptor events by metoprolol treatment in patients with chronic heart failure

OBJECTIVES: This study tested the hypothesis that metoprolol restores the reduction of the inotropic effect of the cyclic adenosine monophosphate (cAMP)-phosphodiesterase inhibitor milrinone, which is cAMP dependent but beta-adrenoceptor independent. BACKGROUND: Treatment with beta-adrenergic blocking agents has been shown to lessen symptoms and improve submaximal exercise performance and left ventricular ejection fraction in patients with heart failure. Restoration of the number of down-regulated beta-adrenoceptors has been suggested to be one mechanism of beta-blocker effectiveness. However, the reversal of postreceptor events, namely, an increase in inhibitory G-protein alpha-subunit concentrations, could also play a role. METHODS: Fifteen patients with heart failure due to dilated cardiomyopathy (left ventricular ejection fraction 24.6 +/- 1.5% [mean +/- SD], New York Heart Association functional class II or III) were treated with metoprolol (maximal dose 50 mg three times daily) for 6 months. Before and after metoprolol treatment, inotropic responses to milrinone (5 to 10 micrograms/kg body weight per min) were measured echocardiographically. For comparison, responses to milrinone were determined under control conditions and after accelerated application of 150 mg of metoprolol to inactivate beta-adrenoceptors in subjects with normal left ventricular function. RESULTS: In subjects with normal left ventricular function, treatment with metoprolol did not alter the increase in fractional shortening or pressure/dimension ratio of circumferential fiber shortening after application of milrinone. In patients with heart failure, treatment with metoprolol significantly increased left ventricular ejection fraction, fractional shortening and submaximal exercise tolerance and reduced heart rate, plasma norepinephrine concentrations and functional class. After metoprolol treatment, milrinone increased fractional shortening but had no effect before beta-blocker treatment. CONCLUSIONS: Milrinone increases inotropic performance independently of beta-adrenoceptors in vivo. Metoprolol treatment restores the blunted inotropic response to milrinone in patients with heart failure, indicating that postreceptor events (e.g., increase in inhibitory G-protein) are favorably influenced. This mechanism could contribute to the beneficial effects observed in the study patients and represents an important mechanism of how beta-blocker treatment influences the performance of the failing heart.     

Regulation of CFTR chloride channels by syntaxin and Munc18 isoforms

The cystic fibrosis gene encodes a cyclic AMP-gated chloride channel (CFTR) that mediates electrolyte transport across the luminal surfaces of a variety of epithelial cells. The molecular mechanisms that modulate CFTR activity in epithelial tissues are poorly understood. Here we show that CFTR is regulated by an epithelially expressed syntaxin (syntaxin 1A), a membrane protein that also modulates neurosecretion and calcium-channel gating in brain. Syntaxin 1A physically interacts with CFTR chloride channels and regulates CFTR-mediated currents both in Xenopus oocytes and in epithelial cells that normally express these proteins. The physical and functional interactions between syntaxin 1A and CFTR are blocked by a syntaxin-binding protein of the Munc18 protein family (also called n-Secl). Our results indicate that CFTR function in epithelial cells is regulated by an interplay between syntaxin and Munc18 isoforms.     

Gestational diabetes mellitus in teenage pregnancy: a case-control study

In a retrospective study, teenage Asian pregnancies with gestational diabetes managed over a 4-year period were compared with a group of age and parity matched controls (2 for each study case) to determine the incidence of gestational diabetes and its impact on the pregnancy outcome. The incidence of gestational diabetes in teenage pregnancy was 5.4% (33/611), and accounted for 1.4% of all the cases of gestational diabetes. There was no difference in the maternal anthropometric parameters or antenatal complications, but the study group had a higher incidence of postpartum haemorrhage (p = 0.010), greater amount of estimated blood loss at delivery (p = 0.016), a trend towards a higher incidence of large-for-gestational age infants, a higher incidence of admission to the neonatal unit (p = 0.024), mostly due to meconium-stained liquor for observation (p = 0.014), and a lower first minute Apgar score (p = 0.012). Our findings support the recommendation that in ethnic groups with a high prevalence of diabetes, universal as opposed to age-limited screening for gestational diabetes should be undertaken.     

The synthesis and enzymatic incorporation of sialic acid derivatives for use as tools to study the structure, activity, and inhibition of glycoproteins and other glycoconjugates

Methods have been developed for the enzymatic synthesis of complex carbohydrates and glycoproteins containing in the sialic acid moiety the heavy metal mercury or the transition-state analog phosphonate of the influenza C 9-O-acetyl-neuraminic acid esterase-catalyzed reaction. 5-Acetamido-3, 5-dideoxy-9-methylphosphono-beta-D-glycero-D-galacto-nonulopyra nosidonic acid (1), 5-acetamido-3,5-dideoxy-9-methylphosphono-2-propyl-alpha-D- glycero-D-galacto-nonulopyranosidonic acid triethylammonium salt (2), and 5-acetamido-9-thiomethylmercuric-3, 5,9-trideoxy-beta-D-glycero-D-galacto-nonulopyranosidonic acid (3) were synthesized. Compounds 1 and 2 are proposed transition state inhibitors of an esterase vital for the binding and infection of influenza C. Compound 3 was enzymatically incorporated into an oligosaccharide and a non-natural glycoprotein for use as an aid in the structure determination of these compounds by X-ray crystallography.     

Inability to establish ectopic endometrium in a natural killer cell-deficient murine model. Immunologic, histologic and histochemical assessment

OBJECTIVE: To investigate what effect natural killer (NK) cells have on the implantation of heterologous endometrial scrapings. STUDY DESIGN: Anti-asialo GM1 (AA-GM1) anti-sera have been shown to eliminate NK cell activity in various strains of rats and mice. Either AA-GM1 antibodies (+) or rabbit antiglobulin (-) was administered to beige mice (NK cell deficient) or beige control mice (not NK cell deficient of the same strain). The heterologous endometrial scrapings were prepared by scraping seven pairs of uterine horns from normal mice of the same strain. Beige and normal mice were then injected intraperitoneally every 3 days with the heterologous endometrial scraping and antibodies for a period of 50 days. The four experimental groups (n = 10 per group) can be summarized as being beige (+), beige (-), normal (+) and normal (-). RESULTS: There was no evidence of ectopic endometrial tissue in any of the four test groups by histologic examination or by using immunohistochemical staining techniques. Histologic evidence of an impaired immune response was clearly demonstrated in the beige mice receiving AA-GM1 antibodies. CONCLUSION: Using this model, a deficiency of NK cell activity did not appear to enhance the implantation of endometrial tissue on the abdominal peritoneum of mice.     

7-Oxo-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridines as novel inhibitors of human eosinophil phosphodiesterase

High-throughput file screening against inhibition of human lung PDE4 led to the discovery of 3-ethyl-1-(4-fluorophenyl)-6-phenyl-7-oxo-4, 5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine (11) as a novel PDE4 inhibitor. Subsequent SAR development, using an eosinophil PDE assay, led to analogues up to 50-fold more potent than 11 with IC50 values of 0.03-1.6 microM. One such compound, CP-220,629 (22) (IC50 = 0.44 microM), was efficacious in the guinea pig aerosolized antigen induced airway obstruction assay (ED50 2.0 mg/kg, po) and demonstrated a significant reduction in eosinophil (55%), neutrophil (65%), and IL-1beta (82%) responses to antigen challenge in atopic monkeys (10 mg/kg, po).     

The clearance of carbon-14-fructose, carbon-14-glucose, and carbon-14-sorbitol by calves at birth and 7 days of age.

Prior to birth, the calf is solely dependent on maternal energy sources. Dramatic changes in blood concentrations of carbohydrates, hormones, and enzymes occur, enabling the neonate to achieve homeostasis. Many of these changes are not well understood. This study was to monitor the metabolism and disappearance of labeled carbohydrates in conjunction with endogenous fructose and glucose. Calves were infused intravenously with 100 muCi of [U-14C]D-fructose, -glucose, or -sorbitol within 12 min of birth and at 7 d of age. Close-interval blood and urine samples were collected until 720 min postinfusion. Radiolabel from the three carbohydrates was separated into parent compound fractions of HPLC. Concentrations of cortisol, insulin, glucose, and fructose were determined from blood. Serum cortisol concentration was 3 to 10 times higher in calves at birth than at 7 d of age. Serum insulin concentrations increased postfeeding in newborn and 7-d-old calves. Insulin concentrations were related to plasma glucose. Endogenous plasma fructose was 63 mg/dl (SE = 7) at birth and was undetectable after 14 h. Glucose was 60 mg/dl (SE = 1) and 92 mg/dl (SE = 8) at birth and at 7 d, respectively. Clearance of radiolabel from glucose at birth and for all the carbohydrates at d 7 was similar. Fructose and sorbitol were cleared more slowly at birth. Radiolabel from fructose at birth was converted very slowly to glucose, but this conversion was rapid at d 7.Sorbitol was converted to fructose at birth but changed quickly to glucose at d 7. The 24-h excretion of radiolabel in urine was less than 4% for fructose and glucose at birth and at d 7. The label from sorbitol appeared in urine at birth (32%) and at d 7 (10%). A source of fructose may provide a slowly utilizable energy source until blood glucose concentrations become stable in the newborn calf.