Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023890 (cirrhosis)
 42,195 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous observations raised the possibility that circulating GH-binding protein (GHBP) may serve as a useful index for tissue GH receptor (GHR) responsiveness in humans. Indeed, there are many examples to indicate that across a wide scope of comparative studies, ontogenic data, experimental systems, physiological conditions, nutritional states, and diseases there is a close relationship between the concentration of GHR and the level of serum GHBP. In the present review, we discuss various aspects that might affect differentially cellular GHR and circulating GHBP, based on species and tissue divergence, regulation of cell-surface GHR turnover, GHR cleavage mechanism, GHR mRNA splicing, and GH insensitivity (GHI) syndrome patients with normal or high serum GHBP levels. Most previous experimental data were collected through comparative analysis of human GHBP against GHR and GHBP determinations in animal models. Yet, GHBPs possess species-specific properties, and the mechanism for their generation and regulation display evolutionary divergence. Another important aspect is tissue divergence, in terms of GHR regulation and its cleavage to GHBP. Although GHBP is generated mainly from the liver GHR, many other tissues express GHRs and probably also contribute to the total GHBP level. Human GHBP is generated by proteolytic cleavage of GHR at the cell-surface and, thus, occupancy or modulation of GHR turnover/internalization would impact the level of cell-surface GHR that are available for proteolysis. An additional degree of complexity arises from recent reports, implicating a protein kinase C-regulated metalloprotease activity in GHBP generation. This suggests that the proteolytic system, which controls the specific cleavage mechanism and switch between GHR proteolysis and GHBP shedding, is a regulated process. Finally, differential splicing regulation to the full-length, active human GHR (hGHR) and the inactive truncated hGHRtr isoform messenger RNA transcripts might regulate both the production of GHBP and GHR bioactivity, as hGHRtr generates large amounts of GHBP but has a dominant negative effect on GH signaling. Several clinical GH-resistant conditions, such as liver cirrhosis, renal insufficiency, insulin-dependent diabetes mellitus, hypothyroidism, malnutrition, or critical illness are associated with reduced GHBP levels. However, this is not universally true, as in other conditions (e.g. early childhood, acromegaly) decreased GHBP levels are not associated with GHI. Divergence between serum GHBP and insulin-like growth factor I, such as which occur during puberty or obesity, also questions whether GHBP levels reflect GHR function. Even in patients with GHI syndrome, serum GHBP cannot be relied on to detect all GHR mutations. The correct assessment of GHR expression and GH functionality in an individual patient will require, in parallel to measurements of serum GHBP, additional detailed diagnostic screening of the entire GH-insulin-like growth factor I axis.
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PMID:Clinical review 112: Does serum growth hormone (GH) binding protein reflect human GH receptor function? 1072 17

The growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis is disturbed in cirrhosis, with elevated basal GH and low IGF-I levels relating to liver function and prognosis. In plasma, GH is bound to a high-affinity GH-binding protein (GHBP), which has been found to be slightly reduced in cirrhosis, but with huge variations. GHBP is identical to the extracellular part of the hepatic GH receptor, but other tissues may contribute to the circulating GHBP levels. The aim was therefore to measure circulating and regional concentrations of GHBP in relationship to hepatic function and body composition in patients with cirrhosis (n = 38) and controls with normal liver function (n = 29). Blood samples from the hepatic, renal, and femoral veins and the femoral artery were collected simultaneously during a hemodynamic investigation. Plasma GHBP was directly measured by a specific and sensitive fluoroimmunoassay. Circulating GHBP levels were identical in the patients and controls (mean +/- SD) 1.03 +/- 0.56 nmol/L and 1.02 +/- 0.55 nmol/L, respectively (not significant). We found no significant hepatic, renal, or peripheral arteriovenous extractions or generations of GHBP, and it did not significantly correlate to liver function. In the controls, GHBP correlated significantly with body mass index (BMI) (r =.60, P <.005), whereas this relationship was not found in the patients with cirrhosis. In conclusion, high-affinity GHBP appears to be normal in patients with cirrhosis, with no significant hepatic generation or renal extraction and no association with the severity of the liver disease. Thus, our study supports the hypothesis that tissues other than the liver, despite its abundant GH receptors, may contribute to the circulating GHBP.
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PMID:A comparison of circulating and regional growth hormone-binding protein in cirrhosis. 1169 54

GH hypersecretory states include organic and functional causes. Among functional GH hypersecretory states, enhanced somatotroph secretion physiologically occurs at birth associated with reduced IGF-I levels reflecting the still immature sensitivity of liver to circulating GH levels; this may also occur in women exposed to oral extrogens. Pathophysiological conditions of GH hypersecretion are generally associated with congenital or acquired/functional conditions of peripheral GH insensitivity. Genetic alterations of the GH receptor lead to the so called Laron's syndrome. On the other hand, a relevant number of clinical conditions (malnutrition, malabsorption, anorexia nervosa, liver cirrhosis, renal failure, Type 1 diabetes mellitus) are associated with acquired GH insensitivity and a more or less pronounced GH hypersecretion. Both organic and acquired conditions of GH insensitivity show low IGF-I synthesis and release and therefore lack the negative IGF-I feedback action on somatotroph function. GH hypersecretion may be associated with renal failure; however, in this case, the alteration in the metabolic clearance rate of GH would also have a role; moreover, IGF-I levels are generally normal in this condition. Hyperthyroidism is another condition connoted by elevated GH levels that reflects a true GH hypersecretory state and is, in fact, associated with high-normal IGF-I levels; this peculiar condition is likely to be reflecting the stimulatory effect of thyroid hormones on both GH and IGF-I secretion and is promptly reversed by treatment-induced euthyroidism. Apart from these "functional" hypersecretory state, the classic organic GH hypersecretory state is represented by acromegaly or giantism. In these conditions GH hypersecretion is generally sustained by a pituitary adenoma hypersecreting GH alone or together with another pituitary hormone, mostly PRL; less frequently GH hypersecretion may be due to ectopic GHRH hypersection. Exaggerated GH secretion elicits exaggerated IGF-I synthesis and secretion that is, in turn, responsible for the large majority of endocrine signs and symptoms. In the appropriate clinical context of acromegalic features, evidence of concomitant marked GH and IGF-I hypersecretion at baseline demonstrates active acromegaly or giantism and indicates the need for magnetic resonance imaging in order to verify the presence of a pituitary tumor. However, as random measurement of basal GH levels is not reliable for definite diagnosis of acromegaly, it is considered mandatory to rely on the lack of GH suppression below 1 microg/l during oral glucose tolerance test (OGTT) coupled with elevated IGF-I levels. The same criteria are assumed, at present, to define true cure of the disease after (or under) treatment. There is consensus about the assumption that concomitant normalization or persistent abnormality of both OGTT-induced GH nadir and IGF-I levels define a successfully or a poorly controlled disease status, respectively. On the other hand, acromegalic patients with GH nadir above 1 microg/l or IGF-I levels persistently elevated are inadequately controlled and their disease should not be considered inactive. It has been clearly demonstrated that an extended exposure to GH and IGF-I excess level, even if slight, has a very harmful effect on patients; therefore early diagnosis of acromegaly and appropriate definition of its cure are of fundamental extreme in order to plan a prompt and appropriate therapeutic intervention(s) guaranteed also by the continuous improvement in the therapeutic tools available to treat this systemic disease.
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PMID:Hormonal diagnosis of GH hypersecretory states. 1549 57

Resistance to the action of growth hormone (GH) frequently complicates liver cirrhosis, while, physiologically, the activation of GH receptor (GHR) determines phosphorylation of signal transducer and activator of transcription (STAT)-5 and the consequent induction of insulin-like growth factor-1 (IGF-1) expression. The suppressor of cytokine signaling (SOCS)-3 negatively regulates this intracellular cascade. We aimed to evaluate the hepatic expression of the GH/IGF-1 axis components in the liver of patients with HCV-related chronic hepatitis at different fibrosis stages. The expression of GH/IGF-1 axis components, such as GHR, IGF-1, STAT5-p, and SOCS-3, was assessed by immunohistochemistry at the lobular level in 61 patients with HCV-related hepatitis. At the hepatocyte level, IGF-1 and nuclear STAT5-p positivity scores showed negative correlations with fibrosis stage, while SOCS-3 score a positive one (p<0.05 for all). Furthermore, the reduction of hepatocyte score of IGF-1 expression was associated with the serological parameters of liver damage (p<0.05) and with the increase of the score of IGF-1 expression by hepatic stellate cells (p<0.05). IGF-1 expression by hepatocytes was reduced with fibrosis progression, probably due to the impairment of GHR intracellular cascade by the SOCS-3 activation already in pre-cirrhotic stages. The inverse correlation between IGF-1 expressed by hepatocytes and by hepatic stellate cells suggests that IGF-1 may exert specific functions in different hepatic cells.
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PMID:Impairment of GH/IGF-1 Axis in the Liver of Patients with HCV-Related Chronic Hepatitis. 2892 79


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