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Objective Lanreotide Autogel® 120 mg (ATG120; Ipsen S.p.A, Milan, Italy) is a high-dose, sustained-release aqueous gel formulation, supplied in a prefilled syringe and given by deep subcutaneous injection. The aim of this study was to compare efficacy and tolerability of ATG120 given every 4–8 weeks with those of octreotide LAR (o-LAR) given every 4 weeks. Design patients and intervention A phase III multicentre Italian open clinical study of 23 acromegalic patients (15 female, 8 male). All patients had received o-LAR for 6–18 months and, after 3 months wash out, ATG120 was given every 6 weeks for a total of four injections (Period 1). Then the interval between ATG120 injections was adjusted according to three different schemes: every 4, 6 or 8 weeks depending on GH levels (GH > 2·5 µg/l; 1 < GH ≤ 2·5 µg/l; GH ≤ 1 µg/l, respectively). ATG120 was given for a further two to three doses, with a final assessment (Period 2) at Week 34, 36 or 42. Measurements Hormonal (GH and IGF-I) and clinical efficacy and tolerability. Results ATG120 induced a significant GH decrease from 9·9 ± 11·3 at baseline (Visit 1) to 3·5 ± 5·7 at the end of Period 1 ( P < 0·01) and to 3·8 ± 5·7 µg/l at the final visit ( P < 0·01). IGF-I also decreased from 544 ± 312 at baseline (Visit 1) to 318 ± 181 at Period 1 and to 356 ± 187 µg/l at the final visit (both P < 0·05 vs. baseline). The frequency of ATG120 administrations was adjusted to every 4 weeks in 12 patients, every 6 weeks in 4 patients and every 8 weeks in 6 patients; 1 patient withdrew before the dose adjustment. Serum GH and IGF-I achieved at the end of Period 1 and Period 2 were similar to those reached with o-LAR. The number of patients who achieved GH < 2·5 µg/l was comparable between o-LAR (43%) and ATG120 at Period 1 (48%) and at Period 2 (62%). Normal IGF-I levels were recorded in 8 patients during o-LAR (35%), 11 during ATG Period 1 (48%) and 10 at the final visit (43%). Last, 4 patients showed a better response to ATG120 and 2 to o-LAR. Conclusions Lanreotide Autogel 120 mg is an effective and well-tolerated therapy for acromegaly. In approximately half of patients ATG120 may be administered every 6–8 weeks, instead of every 4 weeks, without lost of efficacy. [ABSTRACT FROM AUTHOR]

Summary objective Within an appropriate clinical context, GH deficiency (GHD) in adults must be demonstrated biochemically by a single provocative test. Insulin-induced hypoglycaemia (ITT) and GH-releasing hormone (GHRH) + arginine (ARG) are indicated as the tests of choice, provided that appropriate cut-off limits are defined. Although IGF-I is the best marker of GH secretory status, its measurement is not considered a reliable diagnostic tool. In fact, considerable overlap between GHD and normal subjects is present, at least when patients with suspected GHD are considered independently of the existence of other anterior pituitary defects. Considering the time and cost associated with provocative testing procedures, we aimed to re-evaluate the diagnostic power of IGF-I measurement. design To this goal, in a large population [n = 237, 139 men, 98 women, age range 20–80 years, body mass index (BMI) range 26·4 ± 4·3 kg/m2 ] of well-nourished adults with total anterior pituitary deficit including severe GHD (as shown by a GH peak below the 1st centile limit of normal response to GHRH + ARG tests and/or ITT) we evaluated the diagnostic value of a single total IGF-I measurement. IGF-I levels in hypopituitary patients were evaluated based on age-related normative values in a large population of normal subjects (423 ns, 144 men and 279 women, age range 20–80 years, BMI range 18·2–24·9 kg/m2 ). results Mean IGF-I levels in GHD were lower than those in normal subjects in each decade, but not the oldest one (74·4 ± 48·9 vs. 243·9 ± 86·7 µg/l for 20–30 years; 81·8 ± 46·5 vs. 217·2 ± 56·9 µg/l for 31–40 years; 85·8 ± 42·1 vs. 168·5 ± 69·9 µg/l for 41–50 years; 82·3 ± 39·3 vs. 164·3 ± 60·3 µg/l for 51–60 years; 67·5 ± 31·8 vs.... [ABSTRACT FROM AUTHOR]

Summary. Patients older than 65 years represent 3–5% of all acromegalic patients. The old age of the patients and the higher incidence of cardiovascular and metabolic complications related to acromegaly could increase the intra- and peri-operative risk, so that medical treatment is usually recommended as a therapy of choice. The aim of this retrospective study was to investigate the impact of transsphenoidal surgery in a series of 22 elderly patients with active acromegaly, with special regard to anaesthesiological risk, peri-operative complications, and clinical outcome. Despite an increased anesthesiological risk being present in 16/22 patients, no complication occurred during surgery. Similarly, no post-operative mortality or major complications were observed. Biochemical cure, defined at 6 months by glucose-suppressed plasma GH levels below 1 ng/ml and normal age-corrected IGF-I value levels, was achieved in 68% of patients and no recurrence of disease was observed in the subsequent follow-up (mean 5.2±2.1 years). A significant cardiovascular improvement was observed in cured patients, with a decrease of left ventricular mass index (91.3±20.1 vs 115.9±15.0 g/m2; P<0.005), as measured by echocardiography, as well as a slight but significant decrease of systolic and diastolic blood pressure values (130.0±12.1 mmHg vs 137.6±13.5 mmHg P<0.05; and 84.2±6.4 mmHg vs 88.8±7.5 mmHg P<0.05, respectively). A significant post-operative improvement of glucose tolerance was also observed in this group. We conclude that transsphenoidal surgery, if well planned and carefully performed, is safe and able to induce a significant cardiovascular and metabolic improvement even in elderly acromegalic patients. [ABSTRACT FROM AUTHOR]

BACKGROUNDHypertension represents a well-known risk factor for cardiovascular diseases. The pathogenesis of hypertension in acromegaly is commonly viewed as multifactorial, but the possible influence of metabolic disorders on blood pressure (BP) in affected patients is largely unknown. OBJECTIVEThe aim of the present study was to evaluate the impact of glucose metabolism abnormalities on BP values in a series of patients with active acromegaly. DESIGNAn open multicentre prospective study. PATIENTSSixty-eight patients with active disease, aged 47·5 ± 11·7 years, have been studied. Thirty-nine had normal glucose tolerance (NGT), 16 impaired glucose tolerance (IGT) and 13 suffered from diabetes mellitus (DM). MEASUREMENTSMean clinical BP values were calculated as the mean of BP values obtained by sphygmomanometric measurement in three separate occasions and mean 24-h, diurnal and nocturnal systolic (SBP) and diastolic (DBP) values were obtained by 24-h ambulatory blood pressure monitoring (ABPM). RESULTSPatient's age and the degree of glucose tolerance abnormalities were found to significantly and independently influence BP values. All clinical and ABPM SBP and DBP values significantly increased with age by linear regression (P < 0·02 for all BP values, 0·30 ≤ R ≤ 0·43), and the independent influence of this parameter on BP values was confirmed by mutivariate analysis. Similarly, the independent influence of glucose tolerance abnormalities on BP values was confirmed when introducing age as a covariable in a multivariate analysis, and patients with DM presented significantly higher clinical SBP and 24-h, diurnal and nocturnal SBP and DBP than patients with NGT (P < 0·02 for clinical SBP, P < 0·015 for all ABPM values, respectively). In addition, patients with DM showed significantly higher 24-h, diurnal and nocturnal DBP than those with IGT (P < 0·05 in all cases). In contrast, no significant difference... [ABSTRACT FROM AUTHOR]

The article presents a case study of a man with right atrial myxoma, thyroid nodules, and acromegaly which suggests a case of Carney complex.

OBJECTIVE We analysed the effects of 6-months' treatment with octreotide s.c. and lanreotide-SR on circulating GH and IGF-I levels in acromegaly. DESIGN Open retrospective study. PATIENTS Thirty-eight patients with active acromegaly (plasma IGF-I levels greater than 2 standard deviations for age-matched controls and increased serum GH levels not suppressible by oral glucose load) were studied. All patients received s.c. octreotide at a dose of 150-600 μg/day for six months as first therapy and subsequently, lanreotide i.m., 30-60 mg either at 14 or 10 day intervals, for 6 months. A 3 months' washout was applied before starting lanreotide treatment. MEASUREMENTS Mean serum GH levels (from three samples), IGF-I, and clinical examination were performed before and 30, 60, 90 and 180 days after octreotide and lanreotide treatments. Safety tests, HbA1c and, thyroid function were evaluated every three months. RESULTS Circulating GH and IGF-I levels were significantly reduced (P < 0.001) after one, three and six months of both octreotide and lanreotide treatment. The absolute values were lower and the percent decrease in serum GH levels obtained after octreotide treatment was significantly greater, at all scheduled assessments, than after lanreotide (P < 0.01). Serum IGF-I levels during octreotide were significantly lower only after the first month of therapy (P < 0.01). CONCLUSIONS Our study shows that octreotide s.c. is able to induce an earlier reduction in IGF-I levels and a more marked reduction in GH levels than lanreotide. However, after six months of therapy the number of patients with safe GH levels and normal IGF-I age-matched levels, was similar with both drugs. Therefore we suggest that octreotide treatment be preferentially used in the short-term presurgical treatment, while lanreotide can be used in chronic therapy when better compliance is necessary. [ABSTRACT FROM AUTHOR]

Hybrid receptors composed of an insulin alphabeta-hemireceptor and a type 1 IGF alphabeta-hemireceptor are formed in tissues expressing both molecules. We recently reported an increased hybrid receptor expression in skeletal muscle of type 2 diabetic patients that is inversely correlated with in vivo insulin sensitivity. It is unclear whether these changes were due to primary abnormalities or to secondary derangements acting in vivo, such as hyperglycemia. To address this, we determined abundance of hybrids in skeletal muscle from three groups of rats: controls, diabetic (90% pancreatectomy), and diabetic treated with phlorizin to normalize plasma glucose levels. We found that the abundance of hybrid receptors was higher in diabetic rats compared with control and phlorizin-treated diabetic rats (percentage of 125I-insulin bound versus total added radioactivity [B/T] = 1.8+/-0.11, 0.4+/-0.01, and 0.32+/-0.04, respectively; P < 0.0001). Fasting plasma glucose levels were positively correlated with hybrids abundance (r = 0.77, P < 0.002). Hybrid receptor protein content, assessed by immunoblotting, was 2.4-fold higher in diabetic rats as compared with control and phlorizin-treated diabetic rats. Because it has been shown that some of the regulatory effects of glucose may be mediated by the glucosamine pathway, we subsequently determined the effect of an in vivo glucosamine infusion on hybrid receptor formation. We found that abundance of hybrids was significantly higher in muscle from glucosamine-treated rats compared with control rats (B/T = 0.17+/-0.02 and 0.11+/-0.01, respectively; P < 0.009). Quantitation of hybrid content by immunoblotting revealed that their abundance was 1.9-fold higher in glucosamine-treated rats. The results demonstrate that 1) elevated glucose levels in diabetic rats are associated with increased expression of hybrid receptors in muscle, 2) correction of hyperglycemia with phlorizin completely reverses increased expression of hybrids, and 3) glucosamine infused into control rats mimics the effects of hyperglycemia on hybrid receptor formation. Thus, the results support the hypothesis that glucose acting, at least in part, through the glucosamine pathway may play an important role in regulating hybrid receptor assembly in vivo. [ABSTRACT FROM AUTHOR]

OBJECTIVE Hypertension is thought to play an important role in the pathogenesis of acromegalic cardiomyopathy. So far, hypertension has been defined by clinical measurement, with considerable variations reported concerning its prevalence in acromegalics. DESIGN To determine the mean blood pressure (BP) values and the prevalence of hypertension in patients with active acromegaly according to non-invasive 24-hour ambulatory BP monitoring (ABPM) and to compare the data obtained with those provided by clinical measurement. PATIENTS Forty patients with active acromegaly (22 women, 18 men, mean age 48.6 ± 12.5 years) were included. Patients were in wash-out for antihypertensive treatment and none had been using any medical treatment for acromegaly for at least 3 months before the study. All were studied as outpatients. MEASUREMENTS Clinical BP values were calculated as the mean of BP values obtained by standard sphygmomanometric measurement in three separate occasions. Mean 24-hour, daytime and night-time BP values were obtained by ABPM. RESULTS The mean 24-hour BP values were lower than clinical BP values, the difference being significant for both systolic BP (SBP: 131.1 ± 21.5 versus 136.1 ± 16.3 mmHg, P < 0.02) and for diastolic BP (DBP: 74.6 ± 10.6 versus 88.8 ± 9.1 mmHg, P < 0.0001). ABPM values recorded during the daytime were 137.8 ± 20.9 mmHg for SBP and 78.6 ± 11.5 mmHg for DBP, the latter being significantly lower than the corresponding clinical BP values (P < 0.0001). About 60% of the patients considered hypertensive by clinical measurement were found to be normotensive by ABPM, thereby decreasing the prevalence of hypertension in this series from 42.5% to 17.5% according to ABPM (P < 0.02). In contrast, all patients defined as normotensive by clinical measurement were also normotensive by ABPM. CONCLUSIONS Ambulatory blood-pressure monitoring indicated a lower prevalence of hypertension in acromegalic patients then... [ABSTRACT FROM AUTHOR]

Several studies have suggested that, in non-insulin-dependent diabetes mellitus, augmented gluconeogenesis is responsible for increased endogenous glucose production (EGP) and in the end determines fasting hyperglycaemia. However, human and animal studies have been conducted by comparing euglycaemic control subjects to hyperglycaemic diabetic probands. We measured EGP and hepatic gluconeogenesis comparing control and diabetic rats in the fasting state (with diabetic animals in hyperglycaemia), re-examining them in the presence of identical euglycaemia (with diabetic rats made acutely euglycaemic through i. v. phloridzin) or during a hyperinsulinaemic clamp. All rats were infused with [3-3H]-glucose and [U-14C]-lactate; the ratio between 14C-uridine-diphosphoglucose (reflecting 14C-glucose 6-phosphate) and 2 ·14C-phosphoenolpyruvate specific activities (both purified by high performance liquid chromatography from liver) measured hepatic gluconeogenesis. In diabetic animals, although overall EGP ( ∼ 19.5 mg · kg–1· min–1) remained unaffected by experimental euglycaemia, the contribution of glycogenolysis largely increased (from 5.4 to 11.7 mg · kg–1· min–1, hyper- vs euglycaemia) while gluconeogenesis decreased (from 14.0 to 8.1 mg · kg–1æ min–1); both were responsible for the augmented EGP (control rats, EGP: 12.7 mg · kg–1· min–1; gluconeogenesis: 5.9 mg · kg–1· min–1; glycogenolysis: 6.7 mg · kg–1· min–1). Finally, during insulin clamp, gluconeogenesis and glycogenolysis were similarly decreased, and both contributed to the hepatic insulin-resistance of diabetic animals. We conclude that, in this model of non-insulin-dependent diabetes, augmented gluconeogenesis is not primarily responsible for fasting hyperglycaemia and hepatic insulin resistance. Finally, failure to accurately match the experimental conditions in which diabetic and control humans or animals are compared affects gluconeogenesis, overestimating its role in determining hyperglycaemia. [Diabetologia (1998) 41: 307–314] [ABSTRACT FROM AUTHOR]

Alternative splicing of the 36-base pair exon 11 of the human insulin receptor gene results in the synthesis of two insulin receptor isoforms with distinct functional characteristics (the isoform containing exon 11 has lower insulin binding affinity and lower internalization rate). Altered expression of these insulin receptor isoforms has been previously demonstrated in skeletal muscle of patients with non-insulin-dependent diabetes mellitus (NIDDM). However, this observation was not confirmed by other studies and is still a matter of controversy; furthermore, it is not known whether it represents a primary event or is secondary to hyperinsulinaemia and insulin resistance. In order to address this issue in patients with pure non-genetically determined hyperinsulinaemia, we examined the alternative splicing of insulin receptor mRNAs in skeletal muscle of eight patients with surgically confirmed insulinoma and insulin resistance and in eight healthy subjects, using the reverse transcriptase-polymerase chain reaction technique. The insulinoma patients displayed a significant increase in the expression of the insulin receptor isoform containing exon 11 (75.7±2.3%) when compared with normal subjects (57.9±1.5%); furthermore, this increase was positively correlated with plasma insulin concentration and negatively correlated with in vivo insulin sensitivity (glucose clamp). In conclusion, the increased expression of the insulin receptor isoform with lower insulin binding affinity in patients with primary non-genetically determined hyperinsulinaemia supports a role for insulin in the regulation of alternative splicing of insulin receptor pre-mRNA and suggests that in NIDDM an altered receptor isoform distribution might be secondary to the ambient hyperinsulinaemia rather than representing a primary defect. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that glucosamine, a putative activator of glucose toxicity in vitro through acceleration of the hexosamine pathway, may determine in vivo the two key features of glucose toxicity in diabetes, namely, peripheral insulin resistance and decreased insulin secretion. Two groups of awake rats were studied either with intraarterial administration of glucosamine (5 Μmol·kg· min) or saline. Insulin secretion was determined after arginine, glucose (hyperglycaemic clamp), and arginine/glucose infusions, while insulin-mediated glucose metabolism was assessed by the euglycaemic hyperinsulinaemic clamp in combination with [3-H]-glucose infusion. Glucosamine had no effects on arginine-induced insulin secretion both at euglycaemia and hyperglycaemia, but significantly (40-50%) impaired glucose-induced insulin secretion (both first and second phases). During euglycaemic hyperinsulinaemic clamp studies, glucosamine decreased glucose uptake by ∼30%, affecting glycolysis (estimated from HO rate of appearance) and muscle glycogen synthesis (calculated from accumulation of [H]-glucosyl units in muscle glycogen) to a similar extent. Muscle glucose 6-phosphate concentration was markedly reduced in the glucosamine-infused rats, suggesting an impairment in glucose transport/phosphorylation. Therefore, an increase in hexosamine metabolism in vivo: 1) inhibits glucose-induced insulin secretion, and 2) reduces insulin stimulation of both glycolysis and glycogen synthesis, thereby mimicking in normal rats the major alterations due to glucose toxicity in diabetes. [ABSTRACT FROM AUTHOR]

Sixty-seven insulinomas were investigated by immunohistochemistry using site-directed antibodies against insulin, proinsulin, chromogranin A, HISL-19, and four proteins directly or indirectly involved in the proteolytic processing of proinsulin: the prohormone convertases PC2 and PC3, carboxypeptidase H (CPH) and 7B2. Results were expressed in a six-grade score according to the frequency of immunoreactive tumour cells. Insulin was expressed by all tumours, appearing in either a diffuse or a polarized pattern and being detected in more than 30% of tumour cells in all cases but three. Proinsulin was also expressed in all tumours, with more than 50% of tumour cells immunoreactive in all cases but 5. It was consistently localized in the Golgi apparatus. In about half the cases, moreover, it also showed diffuse cytoplasmic staining, usually with a very sparse distribution. Trabecular and solid insulinomas did not present specific, homogeneous patterns of insulin immunostaining. However, insulin immunoreactivity was much more abundant in trabecular than in solid neoplasms, being present in virtually all tumour cells (score 6) in 50% and 8% of cases, respectively. Virtually all insulinomas expressed PC2, PC3, CPH and 7B2, usually in 30-100% of tumour cells, with a frequency significantly related to that of insulin. However, detection of PC2 and 7B2 was slightly less frequent than that of PC3 and CPH. In consecutive sections these proteins were found to be mostly co-localized with insulin and chromogranin A but not with proinsulin. They were heavily expressed in all 10 tumours with more than 10% of cells showing cytoplasmic proinsulin immunoreactivity, indicating that the leakage of proinsulin from the Golgi compartment is not associated with faulty expression of converting enzymes and possibly reflects a saturated processing capacity. HISL-19 immunoreactivity was found in both Golgi apparatus and insulin stores, indicating that the relevant antigen is different from all other proteins investigated. These results do not support a defect in expression or localization of proinsulin-processing enzymes in most insulinomas. [ABSTRACT FROM AUTHOR]

Previous studies have shown that in patients with primary adult myxoedema (PAM) the rise in blood glucose (BG) and plasma insulin (IRI) after various stimuli is higher and more sustained than in normals, so that in this condition insulin resistance may be hypothesized. In the search for factors involved glucose (BG), insulin (IRI), glucagon (IRG), (assayed with an antiserum which is not specific for pancreatic glucagon) and growth hormone (GH), have been determined in blood during the oral glucose tolerance test, OGTT, (100 g), arginine intravenous infusion, ATT (30 g/30 min), and insulin-induced hypoglycemia, ITT (0.1 kg), in patients with PAM, without clinical diabetes, and in normal control subjects. During OGTT, glucose and IRI levels were higher than normal; on the other hand, IRG (probably gut glucagon, or enteroglucagon) levels were lower than in normals. During ATT blood glucose in PAM was slightly higher than normal at 30′ and lower at 90′ and 120′; insulin levels were higher than normal at any time; GH and IRG (very likely pancreatic glucagon, or nesidioglucagon) responses were lower than normal. During ITT, blood glucose levels dropped slowly but progressively and GH levels were lower than normal. It is concluded that in primary adult myxoedema glucagon, both enteric and pancreatic, and growth hormone secretions are impaired. The resistance to insulin action observed in PAM does not seem to be due to an excess of growth hormone or (nesidioglucagon). [ABSTRACT FROM AUTHOR]

Leptin, a hormone secreted by adipocytes, decreases food intake and increases energy expenditure. The role of insulin in the regulation of leptin secretion is poorly understood and is still a topic of debate. Insulin increases leptin mRNA synthesis in rodents, but in humans, the available data are discordant. To investigate the role of chronic hyperinsulinemia in the regulation of plasma leptin concentrations, we studied 13 patients with surgically confirmed insulinoma before and after tumor removal, along with 15 healthy control subjects matched for sex, age, and BMI. Immunoreactive plasma leptin levels were measured by radioimmunoassay; leptin mRNA levels were also determined by reverse transcription-competitive polymerase chain reaction in a subgroup of six patients with insulinoma and six control subjects. All determinations were made with subjects in the fasting state. Plasma leptin concentrations correlated positively with leptin mRNA levels (r = 0.880, P < 0.001). Leptin levels, both plasma protein and mRNA, were significantly higher in the insulinoma patients than in the control subjects (plasma protein: 17.5 +/- 3.6 vs. 2.9 +/- 0.4 ng/ml, respectively, P < 0.001; mRNA: 0.98 +/- 0.33 vs. 0.19 +/- 0.064 amol/microg RNA, respectively, P < 0.05), and they correlated positively with fasting plasma insulin levels in the patients with insulinoma (plasma protein: r = 0.686, P < 0.01; mRNA: 0.796, P < 0.05). Finally, removal of the insulin-secreting tumor was followed by the normalization of plasma leptin levels. In summary, in patients with insulinoma, 1) plasma leptin levels and leptin mRNA are elevated; 2) a direct relationship exists between leptin, both circulating protein and mRNA, and insulin concentrations; and 3) plasma leptin returns to normal levels after tumor removal. These data, therefore, support a role for insulin in the chronic regulation of leptin gene expression. [ABSTRACT FROM AUTHOR]

The insulin receptor (IR) shares structural and functional homology with the IGF-I receptor (IGF-IR). Hybrid receptors composed of an IR alphabeta-heterodimer and an IGF-IR alphabeta-heterodimer are formed in tissues expressing both molecules. Hybrids behave as IGF-IR rather than IR with respect to ligand binding affinity, receptor autophosphorylation, and hormone internalization and degradation. Factors regulating hybrid formation in vivo are unknown. We recently reported that in skeletal muscle of NIDDM patients, expression of hybrids is increased and correlated with a decrease in IR number and an increase in fasting insulin levels. However, it is not clear whether increased expression of hybrid receptors is a primary defect specifically associated with NIDDM or a secondary event caused by hyperinsulinemia. To address this issue, we used a quantitative microwell-based immunoassay to measure hybrid receptor abundance in skeletal muscle of 11 normal subjects and 12 patients with insulinoma, a state of primary nongenetically determined hyperinsulinemia. Total insulin binding was lower in insulinoma patients than in normal subjects (0.70 +/- 0.18 vs. 4.59 +/- 0.77; P < 0.0001). Total IGF-I binding did not differ between the two groups (0.81 +/- 0.27 and 0.85 +/- 0.10, respectively). The amount of hybrids, expressed as bound/total (B/T), was higher in patients with insulinoma than in normal subjects (0.57 +/- 0.19 vs. 0.36 +/- 0.03; P < 0.0006) and was inversely correlated with total insulin binding (r = -0.64, P < 0.0004). Increased abundance of hybrid receptors was positively correlated with insulin levels (r = -0.82, P < 0.0009) and inversely correlated with insulin-mediated glucose uptake (r = -0.80, P < 0.01). No correlations were observed between insulin-mediated glucose uptake and maximal specific insulin binding (r = 0.19, P = 0.64). These results indicate that insulin-induced IR downregulation may lead to the formation of a higher proportion of hybrid receptors, whose abundance is negatively correlated with in vivo insulin sensitivity. These results, therefore, support a role for insulin in the regulation of hybrid receptors formation and suggest that increased expression of hybrids in NIDDM may be a secondary event caused by hyperinsulinemia rather than a primary defect. [ABSTRACT FROM AUTHOR]

The article focuses on a study which examined mutations in the TSH receptor (TSHR) extracellular region in thyroid functioning nodules. The researchers discovered the occurrence of two unusual heterozygous mutations in two of seven thyroid functioning nodules detected as single nodules or in a multinodular goiter. The implications of the discovery regarding the structure-function relationship of the TSHR is explained.

The sera of ten patients with unexplained hypoglycaemia were examined for antibodies to pancreatic islets. Antibodies to pancreatic A, B and D cells (ICAb) were detected in one patient with an associated gastrointestinal tumour. [ABSTRACT FROM AUTHOR]