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Biomedical subjects

G Baumann

Publications and source records attributed to G Baumann.

At least 55 records · Page 3Linked to original sources

The beta3-adrenergic receptor Trp64Arg mutation is not associated with coronary artery disease.

There is some evidence that the Trp64Arg polymorphism of the beta3-adrenergic receptor (beta3-AR) is associated with atherogenic risk factors that include weight gain, insulin resistance, and diabetes. The objective of this cross-sectional study was to investigate the relationship between the Trp64Arg polymorphism and coronary artery disease (CAD). A total of 1,000 consecutive patients with angiographically confirmed CAD and 1,000 controls, carefully matched for age and sex, were genotyped for the Trp64Arg polymorphism by polymerase chain restriction and subsequent restriction fragment length polymorphism analysis. Among cases with CAD, 83.3% were wild-type Trp/Trp, 15.8% were heterozygotes, and 0.9% were homozygous Arg/Arg compared with 82.3%, 17.3%, and 0.4%, respectively, among controls (P = .27). The odds ratios for the presence of Trp/Arg and Arg/Arg in cases and controls were 0.90 (95% confidence interval [CI] 0.7 to 1.2; P = .40) and 2.2 (95% CI 0.7 to 7.2; P = .17), respectively. There was no effect modification by gender and atherogenic risk factors, including diabetes, hypercholesterolemia, hypertension, and smoking. Furthermore, there was no evidence of an association with premature disease onset (< 40 years) or extent of disease. In conclusion, the results of this study in a large sample of clinically well-characterized patients indicate that neither the Trp/Arg nor the Arg/Arg genotype represents a major risk factor for angiographically confirmed coronary artery disease.

Amino Acid Substitution↗

[Left ventricular reduction surgery: pre- and postoperative evaluation by cine MRI].

AIM: To evaluate the role of cine magnetic resonance imaging (MRI) in the preoperative assessment and postoperative follow-up of patients undergoing left ventricular (LV) reduction surgery. PATIENTS AND METHODS: 6 patients with cardiomegaly were examined on a 1.5 T MR imager before and after LV reduction surgery. The heart was imaged along the short and long axes using a breath-hold ECG-triggered cine gradient-echo sequence for assessing ventricular and valvular morphology and function and performing volumetry (end-diastolic and end-systolic volumes, ejection fraction). RESULTS: Postoperatively, the mean ejection fraction increased from 21.7% to 33.4% and the end-diastolic and end-systolic left ventricular volumes decreased in all patients (304.0 and 252.5 ml before to 205.0 and 141.9 ml after surgery). Mean myocardial mass decreased slightly from 283.8 g to 242.7 g. Differences were significant for all parameters (p < 0.05). MRI allowed for the reliable assessment of post-operative valve morphology and yielded additional findings such as the presence of mitral valve insufficiency or ventricular thrombus. CONCLUSIONS: Cine MRI provides relevant information prior to left ventricular reduction surgery and reliably depicts functional and morphological changes in the early post-operative follow-up.

Aged↗

[Definition of shock types].

Definitions of shock types. Hypovolaemic shock is a state of insufficient perfusion of vital organs with consecutive imbalance of oxygen supply and demand due to an intravascular volume deficiency with critically impaired cardiac preload. Subtypes are haemorrhagic shock, hypovolaemic shock in the narrow sense, traumatic-haemorrhagic shock and traumatic-hypovolaemic shock. Cardiac shock is caused by a primary critical cardiac pump failure with consecutive inadequate oxygen supply of the organism. Anaphylactic shock is an acute failure of blood volume distribution (distributive shock) and caused by IgE-dependent, type-I-allergic, classical hypersensibility, or a physically, chemically, or osmotically induced IgE-independent anaphylactoid hypersensibility. The septic shock is a sepsis-induced distribution failure of the circulating blood volume in the sense of a distributive shock. The neurogenic shock is a distributive shock induced by generalized and extensive vasodilatation with consecutive hypovolaemia due to an imbalance of sympathetic and parasympathetic regulation of vascular smooth muscles.

Anaphylaxis↗

Combined dipyridamole and dobutamine echocardiography in myocardial hibernation: comparison with thallium uptake in patients after percutaneous transluminal coronary revascularization under circulatory support.

OBJECTIVE: To investigate the specificity and sensitivity of the combination of dipyridamole and dobutamine echocardiography for predicting functional recovery in patients with reduced ventricular function after coronary angioplasty. METHODS: Twenty-five patients, mean (SD) age 60.8 (10) years, with previous myocardial infarction (> 3 months), angiographically assessed coronary artery disease, and resting regional dysfunction (left ventricular ejection fraction < 35%) were studied. They underwent rest-redistribution thallium Tl-201 single photon emission computed tomography, and low-dose pharmacologic stress echocardiography with dobutamine (up to 10 microg/kg per minute), ultra low-dose dipyridamole (0.28 mg/kg over 4 minutes), and combined dipyridamole-dobutamine administration. RESULTS: The rate of agreement between Tl-201 and stress echo was 59% for dipyridamole, 62% for dobutamine, and 71% for combined dipyridamole-dobutamine (P <.05 vs dipyridamole and vs dobutamine). Combined dipyridamole-dobutamine showed a higher sensitivity (89%) than Tl-201, dobutamine, or dipyridamole (84%, 78%, and 80%). Specificity was lower for functional recovery prediction with Tl-201 (60%) compared with dobutamine (89%), dipyridamole (90%), and combined dipyridamole-dobutamine (91%). CONCLUSION: Thallium is more sensitive than dipyridamole or dobutamine; the sensitivity gap is filled with combined dipyridamole-dobutamine. Pharmacologic stress echocardiography is more specific than Tl-201 scintigraphy.

Adult↗

The pregnancy hormone relaxin is a player in human heart failure.

Human congestive heart failure is characterized by complex neurohumoral activation associated with the up-regulation of vasoconstricting and salt-retaining mediators and the compensatory rise of counter-regulatory hormones. In the present study, we provide the first evidence that relaxin (RLX), known as a pregnancy hormone, represents a potential compensatory mediator in human heart failure: plasma concentrations of RLX and myocardial expression of the two RLX genes (H1 and H2) correlate with the severity of disease and RLX responds to therapy. The failing human heart is a relevant source of circulating RLX peptides, and myocytes as well as interstitial cells produce RLX. Elevation of ventricular filling pressure up-regulates RLX expression and the hormone acts as a potent inhibitor of endothelin 1, the most powerful vasoconstrictor in heart failure. Furthermore, RLX modulates effects of angiotensin II, another crucial mediator. Our data identify RLX as a new player in human heart failure with potential diagnostic and therapeutic relevance.

Animals↗

Pulmonary adrenomedullin counteracts deterioration of coronary flow and myocardial performance evoked by pulmonary endothelins in experimental acute respiratory distress syndrome.

OBJECTIVES: We recently showed that pulmonary endothelins may affect coronary circulation under various experimental and clinical conditions. Here, we investigated the effect of pulmonary mediators on coronary tone in experimental acute respiratory distress syndrome. We focused particularly on pulmonary endothelin-1, a major vasoconstrictor in acute respiratory distress syndrome, and on adrenomedullin, a potent vasodilator that is up-regulated by inflammatory stimuli. DESIGN: Controlled experiment that used isolated organs. SETTING: Experimental laboratory. SUBJECTS: Wistar rats. INTERVENTIONS: The saline effluent from an isolated lung was used to serially perfuse the coronary vessels of an isolated heart. We compared serial perfusion after 2-hr pretreatment of lungs with vehicle or endotoxin (50 microg/mL), and we used the following drugs to elucidate the coronary response observed: the endothelin type A receptor antagonist BQ-123 (2 microM), the endothelin type B antagonist A-192621 (500 nM), the endothelin-converting enzyme inhibitor phosphoramidon (50 microM), the calcitonin gene-related peptide type-1 receptor antagonist hCGRP(8-37) (2 microM), and the adrenomedullin receptor antagonist hAM(22-52) (200 nM) (n = 6 each). MEASUREMENTS AND MAIN RESULTS: In controls, serial perfusion decreased coronary flow to 87 +/- 3% of baseline (p < .05). BQ-123 and phosphoramidon prevented this effect, whereas blockade of endothelin type B and adrenomedullin-binding receptors had no effect. After endotoxin challenge, coronary flow significantly increased to 110 +/- 2%. This response was augmented by BQ-123 (124 +/- 2%) and phosphoramidon (123 +/- 3%); A-192621 had no effect. Application of hCGRP(8-37) and hAM(22-52) significantly decreased coronary flow to 81 +/- 3% and 88 +/- 2%, respectively. Flow decrease after blockade of both adrenomedullin-binding receptors (73 +/- 2%) significantly deteriorated peak left ventricular pressure, to 82 +/- 6% of baseline; rate of pressure increase, to 81 +/- 5%; and rate of pressure decline, to 77 +/- 6%. Endotoxin pretreatment elevated pulmonary venous big endothelin-1 (three-fold), endothelin-1 (two-fold), and adrenomedullin (five-fold). CONCLUSION: In experimental acute respiratory distress syndrome, pulmonary adrenomedullin--via calcitonin gene-related peptide type-1 receptor and adrenomedullin receptor--outweighs the coronary vasoconstrictor impact of pulmonary big endothelin-1 exerted via endothelin type A receptors after conversion to mature endothelin-1. The consequence is prevention of flow-related deterioration of myocardial performance.

Adrenomedullin↗

Acute hemodynamic effects of beta-blockers in patients with severe congestive heart failure: comparison of celiprolol and esmolol.

The present study was designed to investigate, in patients with severe heart failure, the dose-dependent acute hemodynamic effects of celiprolol versus those of esmolol. Celiprolol is a beta 1 -receptor blocker with vasodilating properties, whereas esmolol is an ultra-short-acting beta 1 -blocker. Included were 14 patients with decompensated chronic heart failure (NYHA class IV) due to coronary heart disease (n = 8) or to dilated cardiomyopathy (n = 6). Each patient received both celiprolol and esmolol in random fashion. The beta-blockers were administered in four dose tiers, with an increase in dosage every 15 min. Hemodynamic measurements were obtained with a Swan-Ganz thermodilution catheter. Administration of celiprolol (5, 10, 20, and 50 microg/kg) took place intravenously. After intravenous administration of a loading dose of 500 microg/kg, we continuously infused esmolol at increasing doses, which were individually titrated for each patient. Mean infusion rates of esmolol were as follows: 40, 75, 140, and 230 micromol/kg per minute. Celiprolol and esmolol induced a comparable dose-dependent decrease in heart rate to a minimum of -10% below baseline. Esmolol caused a significant dose-dependent decrease (-25% below baseline at the highest dose level) in cardiac index (CI). After administration of celiprolol, CI decreased only transiently (-10% below baseline at the second and third dose level) and did not differ from the baseline at the highest dose level. For treatment of severe heart failure, initiation of intravenous beta-blocker therapy with low doses of a beta 1 -blocker with vasodilating effects may have hemodynamic advantages over conventional beta-blockade.

Adrenergic beta-Antagonists↗

R-wave detection by subcutaneous ECG. Possible use for analyzing R-R variability.

BACKGROUND: Atrial arrhythmia (AA) discrimination remains a technological challenge for implanted cardiac devices. We examined the feasibility of R-wave detection by a subcutaneous far field ECG (SFFECG) and analysis of these signals for R to R variability as an indicator of atrial arrhythmia (AA). METHODS: Surface ECG and SFFECG (from the pacemaker pocket) were recorded in sixteen patients (61.5 +/- 11.4 years) with AA. The SFFECG was recorded with a pacemaker sized four electrode array acutely placed in the pacemaker pocket during implantation. The signals were analyzed to obtain peak-to-peak R wave amplitude and R to R interval variability (indicative of AAs). RESULTS: In sixteen patients R waves were visually discernible in all recordings. The percentage over and under detection for automatic R wave recognition SFFECG was 3 and 9%, respectively. R to R variability analysis using the SFFECG produced results concordant to those using the surface ECG. CONCLUSION: SFFECG might be a helpful adjunct in implantable device systems for detection of R waves and may be used for measurement of R to R variability.

Aged↗

Phorbol ester- and growth factor-induced growth hormone (GH) receptor proteolysis and GH-binding protein shedding: relationship to GH receptor down-regulation.

GH signals by interacting with GH receptor (GHR). A substantial fraction of circulating GH complexes with GH-binding protein (GHBP), which corresponds to the GHR extracellular domain. GHBP is generated by 1) alternative splicing of a common GHR precursor messenger RNA to encode secreted GHBP (the source of the vast majority of GHBP in rodents); and 2) proteolysis of the cell-associated GHR with shedding of GHBP (a mechanism operative in rabbits and humans). We previously observed that phorbol ester (PMA)-induced activation of protein kinase C (PKC) causes metalloprotease-mediated GHR proteolysis and GHBP shedding in human IM-9 lymphocytes. We now demonstrate that PMA-induced hydroxamate (IC3)-inhibitable GHR proteolysis and GHBP shedding were also detected in murine 3T3-F442A and 3T3-L1 preadipocytes and in Chinese hamster ovary (CHO) cells stably expressing rabbit GHR (rbGHR), although the degree of GHBP shedding was much smaller for murine GHR than for rabbit or human GHRs. PMA-induced GHR proteolysis in 3T3-F442A, 3T3-L1, and CHO-rbGHR cells was significantly reduced by pretreatment with mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1 inhibitors, suggesting involvement of the mitogen-activated protein kinase pathway in regulating this PKC-dependent effect. In contrast, GHR proteolysis promoted by N-ethylmaleimide, although inhibited by IC3, was unaffected by inhibition of either PKC or mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1. Thus, different pathways leading to metalloprotease-mediated receptor proteolysis are accessed by PMA vs. N-ethylmaleimide. To determine whether other, possibly more physiologically relevant, stimuli induce GHR proteolysis, we tested effects of platelet-derived growth factor (PDGF) and serum. Treatment of serum-deprived cells with PDGF (in 3T3-F442A cells) or serum (in 3T3-F442A and CHO-rbGHR cells) promoted GHR proteolysis, which was inhibited by IC3. Interestingly, PMA-, PDGF-, and serum-induced GHR proteolysis was associated with substantial decreases in GH-induced activation of Janus kinase-2, which were also prevented by IC3. These findings suggest that inducible metalloprotease-mediated GHR proteolysis constitutes an important mechanism of receptor down-regulation and modulation of GH signaling.

3T3 Cells↗

Growth hormone binding protein 2001.

The present state of knowledge about growth hormone binding proteins (GHBP) is reviewed, with particular emphasis on the high affinity GHBP, which represents the circulating ectodomain of the growth hormone receptor (GHR). GHBP is conserved through vertebrate evolution, is produced in many tissues (especially liver) by either alternative GHR mRNA splicing (rodents) or by proteolytic cleavage from the GHR (humans, rabbits and several other species). The metalloprotease TACE (tumor necrosis factor-alpha converting enzyme) is the likely enzyme responsible for cleavage, but the structural requirements for TACE recognition or catalysis, and hence the precise cleavage point in the GHR, are unknown. GHBP is widely distributed in biological fluids, with marked concentration differences amongst them. GHBP binds about half of the circulating GH under basal conditions but is easily saturated at high GH levels; it subserves complex functions, including a circulating buffer/reservoir function for GH, prolongation of plasma GH half-life, competition with GHRs for GH, and probably unproductive heterodimer formation with the GHR. The net effect of these partly enhancing and partly inhibitory functions on GH action in vivo is complex and difficult to ascertain. Serum GHBP levels roughly parallel GHR expression (particularly in liver) through the life span, with very low levels in fetal life, upregulation to adult levels during childhood, and decline in senescence. Rodent pregnancy is associated with a massive increase in GHBP expression. Although the regulation of GHBP expression/production is not necessarily tightly linked to GHR expression, in general, low GHBP levels occur in conditions associated with GH resistance (e.g., malnutrition, uncontrolled diabetes, catabolic states, renal failure, hypothyroidism). Conversely, obesity, a condition with enhanced GH responsivity, is associated with elevated GHBP levels. This suggests that in many (but not all) instances of abnormal GH action, the GHBP level reflects GHR status. Laron syndrome (genetic GHR deficiency/dysfunction due to mutations in the GHR gene) is associated with low or undetectable GHBP in 75-80% of patients; GHBP measurement can therefore be used diagnostically. Depending on the design of assays for serum GH, endogenous GHBP may interfere to varying degrees, and GH assays should be individually validated and optimized in this regard. The ultimate biological role and physiological significance of the GHBP remain to be established.

Aging↗

[Pregnancy risks in acquired heart diseases].

Optimal management of pregnancies for patients with acquired heart disease requires exact knowledge of the hemodynamic influence of pregnancy-related cardiovascular adaptation processes on the heart disease. Maternal and fetal risks must be carefully considered and mutually weighed. Critical time periods, during which closely networked, interdisciplinary support for the patient is essential, are primarily during the 30th to 32nd week of pregnancy. This is the period in which maximum increases in heart rate, cardiac output, and plasma volume are observed. The peripartal phase represents another critical period. Owing to the mechanically related fixation of cardiac output, stenotic valvular diseases are generally tolerated much poorer than are valvular insufficiency defects. Therapeutic objectives are reduction in heart rate and--in cases of pulmonary-venous congestion--decrease in preload. Vaginal deliveries are possible with slight to moderate valvular stenosis; cesarean section is to be preferred in more severe cases. In patients with valvular insufficiency and normal left ventricular function pregnancy is usually well tolerated. Reduction in regurgitation is even often observed owing to pregnancy-induced decrease in peripheral vascular resistance. Since ACE inhibitors and AT1 antagonists are contraindicated during pregnancy, afterload reduction can be achieved by a combination of hydralazin and nitrates, or calcium antagonists. Peripartal cardiomyopathy is rare and is associated with a high degree of maternal mortality (25-50%). Apart from the necessary consideration of pregnancy-related contraindications, therapeutic principles do not differ from those for other forms of heart failure. Most patients exhibiting hypertrophic obstructive cardiomyopathy satisfactorily pass through their pregnancies. Individual cases have been described, however, of both pregnancy-related cardiac decompensation as well as sudden death. Aortal and coronary-arterial dissections represent rare, life-endangering complications for mother and fetus: these developments can occur among predisposed patients as a result of the hormonal and hemodynamic adaptation processes during pregnancy. Close interdisciplinary collaboration and tightly networked support for patients are the prerequisite for successful management of high-risk pregnancies involving maternal heart disease.

Adaptation, Physiological↗

[Pregnancy and congenital heart defects].

With advanced diagnostic and therapeutic techniques in pediatric cardiology and cardiac surgery, pregnancy can be an option for patients with congenital heart disease. A low overall maternal mortality and a healthy pregnancy require interdisciplinary cooperation between the cardiologist, obstetrician and general practitioner caring for the mother. Treatment and outcome will depend on the type of cardiac malformation, on the functional impairment of the maternal heart (heart failure and/or cyanosis) and on the status of the fetus, with evidence of a better outcome for patients treated in specialized centers. However, even with recent advances in treatment, for women with primary pulmonary hypertension, Eisenmenger's syndrome, left heart obstruction of Marfan syndrome, pregnancy remains associated with a high maternal mortality. Therefore, these are conditions in which pregnancy is still absolutely contraindicated and a patient should be counselled to terminate the pregnancy. The risk of an inherited recurrence of a congenital heart disease is difficult to assess in an individual case because the majority of cardiac malformations are caused by multifactored variables. But for some types of malformations (i.e., atrioventricular canal, Morbus Fallot) the incidence of cardiac malformation in the offspring of affected parents is slightly higher compared to the general population. Consequently, all patients with congenital heart disease should be offered genetic counselling and fetal echocardiography. In general, pregnancy in women with congenital heart disease has no significant long-term adverse effects and a second pregnancy is possible in the majority of the cases.

Female↗

Adrenomedullin and myocardial contractility in the rat.

The effects of adrenomedullin in the regulation of myocardial contractility were investigated in the rat. In papillary muscles (n=6), adrenomedullin (0.1 to 10 nM) failed to show contractile effects. NO (nitric oxide) synthase inhibition with N(G)-nitro-L-arginine (L-NOARG) did not unmask any inotropic effect of adrenomedullin. The positive inotropic effect of isoprenaline (0. 01 nM to 10 microM) was identical after adrenomedullin, after L-NOARG, and after L-NOARG plus adrenomedullin (n=6 each). In field-stimulated rat ventricular myocytes, adrenomedullin (1, 10, and 100 nM; n=4 each) had impact neither on cell shortening nor on Ca(2+) transients. In isolated constant-flow perfused hearts (7.3+/-0.3 ml/min), adrenomedullin (1 nM, n=9; 10 nM, n=7) induced significant coronary vasodilation (-28%, -50%). In conclusion, adrenomedullin is a potent coronary vasodilator, but has no significant effects on myocardial contractility in the rat.

Adrenomedullin↗

Reduced procedural risk for coronary catheter interventions in carriers of the coagulation factor VII-Gln353 gene.

OBJECTIVES: We have focused on the role of coagulation factor VII (FVII) Arg353Gln polymorphism as a risk predictor of complications following percutaneous transluminal coronary angioplasty (PTCA), directional coronary atherectomy (DCA), and stenting. BACKGROUND: The FVII Arg353Gln mutation decreases FVII activity, and presence of the Gln353 allele could be protective against thrombus formation during catheter interventions. METHODS: A total of 666 consecutive patients with coronary artery disease who had undergone PTCA (n = 280), DCA (n = 104), or stenting (n = 282) were followed up for a 30-day composite end point, which included need for target vessel revascularization, myocardial infarction, and death. The Arg353Gln polymorphism of FVII was determined by PCR/RFLP assay. RESULTS: Carriers of the Gln353 allele had significantly lower levels of total FVII activity (FVIIc, -20.7%, p < 0.001) and of activated circulating FVII (FVIIa, -32.7%, p = 0.03) compared with Arg353/Arg353. The composite end point occurred in 43 patients: 4 were heterozygous Arg353/Gln353, and 39 were homozygous Arg353/Arg353. The incidence of the composite end point was 2.5% in carriers of the Gln353 allele and 7.7% in Arg353/Arg353 homozygotes (p = 0.013). This corresponds to a 72% risk reduction in carriers of the Gln353 allele (relative risk: 0.28; 95% confidence interval: 0.09-0.81; p = 0.02). CONCLUSIONS: The Gln353 allele of FVII is associated with substantial risk reduction in adverse events that complicate coronary catheter interventions. With the perspective of active site-blocked activated FVII (FVIIai) as conjunctive medication, the results suggest that the FVII genotype should be taken into due consideration in assessment of FVIIai medication and of its dosage.

Aged↗

Pulmonary release and coronary and peripheral consumption of big endothelin and endothelin-1 in severe heart failure: acute effects of vasodilator therapy.

BACKGROUND: We investigated plasma endothelin (ET) levels in patients with congestive heart failure (CHF) during treatment for acute decompensation; we also measured imbalances in ET peptides across the pulmonary, coronary, and peripheral circulation. Methods and Results-In patients with severe CHF (n=21; cardiac index [CI], 1.9+/-0.2 L. min(-1). m(-2); pulmonary capillary wedge pressure [PCWP], 31+/-1 mm Hg), vasodilation was achieved with the nitric oxide donor sodium nitroprusside (n=11) or with the alpha(1)-antagonist urapidil (nitric oxide-independent, n=10). ET concentrations were determined from arterial blood and blood from the pulmonary artery, coronary sinus, and antecubital vein. Depending on sites of measurement, baseline big ET and ET-1 levels were, respectively, 12 to 16 times and 5 to 11 times higher than in controls (n=11), and 4 to 6 times and 2 to 3 times higher than in patients with moderate CHF (n=10; CI, 2.7+/-0.3 L. min(-1). m(-2); PCWP, 14+/-2 mm Hg). Patients with severe CHF demonstrated pulmonary net release and coronary and peripheral net consumption of both peptides (ie, arterial levels [big ET, 7.3+/-1.3 pmol/L; ET-1, 1.8+/-0.1 pmol/L] were higher than levels in the pulmonary artery [6.7+/-1.2 pmol/L; 1. 3+/-0.1 pmol/L], coronary sinus [6.4+/-1.0 pmol/L; 1.4+/-0.1 pmol/L], and antecubital vein [6.6+/-1.1 pmol/L; 1.3+/-0.1 pmol/L]). In these patients, sodium nitroprusside (SNP) and urapidil resulted in comparable hemodynamic improvement after 6 hours (CI: SNP, 63+/-2%; urapidil, 72+/-3%; PCWP: SNP, -50+/-2%; urapidil, -47+/-2%) and a maximum decrease in ET peptides by >50%. After 3 hours, pulmonary net release and coronary and peripheral net consumption were no longer detectable. CONCLUSIONS: In patients with severe CHF, the lungs act as a producer and the heart and the periphery act as consumers of elevated circulating ETs. Short-term vasodilator therapy decreases ETs and restores their pulmonary, coronary, and peripheral balance.

Aged↗

Disproportional skeletal growth and markedly decreased bone mineral content in growth hormone receptor -/- mice.

Growth hormone (GH) is important for skeletal growth as well as for a normal bone metabolism in adults. The skeletal growth and adult bone metabolism was studied in mice with an inactivated growth hormone receptor (GHR) gene. The lengths of femur, tibia, and crown-rump were, as expected, decreased in GHR-/- mice. Unexpectedly, GHR-/- mice displayed disproportional skeletal growth reflected by decreased femur/crown-rump and femur/tibia ratios. GHR-/- mice demonstrated decreased width of the growth plates in the long bones and disturbed ossification of the proximal tibial epiphysis. Furthermore, the area bone mineral density (BMD) as well as the bone mineral content (BMC)/body weight were markedly decreased in GHR-/- mice. The decrease in BMC in GHR-/- mice was not due to decreased trabecular volumetric BMD but to a decreased cross-sectional cortical bone area In conclusion, GHR-/- mice demonstrate disproportional skeletal growth and markedly decreased bone mineral content.

Animals↗