Assessment of biological and colony hybridization assays for detection of the aerobactin system in Escherichia coli from urinary tract infections

A total of 466 E. coli strains from urinary tract infections (UTI) were screened for the presence and expression of the aerobactin system by a colony hybridization test and a bioassay. A probe carrying part of the genes for aerobactin synthesis was used. A total of 43.1% (201) of the strains were positive in the probe test and undoubtedly positive in the bioassay. When doubtfully positive bioassays were included, this figure rose to 49.8% (232). An additional 4.9% (23) of the strains were positive in the colony hybridization test only while 44% (205) of the strains were negative in both tests. Doubtfully positive bioassays were probably due either to a false positive reaction or to a weak expression of the aerobactin system. 01:K1:H- strains were characteristically probe positive and doubtfully positive in the bioassay. The incidence of isolates positive by both methods or by only one of them was significantly higher among isolates from cases of pyelonephritits (Py) than among those from asymptomatic bacteriuria (ABU) and normal feces (FN) (P<0.01).     

Acute Hyperinsulinemia Restrains Endotoxin-induced Systemic Inflammatory Response: An Experimental Study in a Porcine Model

Background: Intensive insulin therapy in critically ill patients reduces morbidity and mortality. The current study elucidates whether acute hyperinsulinemia per se could attenuate the systemic cytokine response and improve neutrophil function during endotoxin (lipopolysaccharide)-induced systemic inflammation in a porcine model.

Methods: Pigs were anesthetized, mechanically ventilated, randomized into four groups, and followed for 570 min: group 1 (anesthesia solely, n = 10), group 2 (hyperinsulinemic euglycemic clamp [HEC], n = 9), group 3 (lipopolysaccharide, n = 10), group 4 (lipopolysaccharide-HEC, n = 9). Groups 3 and 4 were given a 180-min infusion of lipopolysaccharide (total, 10 [mu]g/kg). Groups 2 and 4 were clamped (p-glucose: 5 mm/l, insulin 0.6 mU [middle dot] kg-1 [middle dot] min-1) throughout the study period. Changes in pulmonary and hemodynamic function, circulating cytokines, free fatty acids, glucagon, and neutrophil chemotaxis were monitored.

Results: Tumor necrosis factor [alpha] and interleukin 6 were significantly reduced in the lipopolysaccharide-HEC group compared with the lipopolysaccharide group (both P = 0.04). In the lipopolysaccharide-HEC group, the glucagon response was diminished compared with the lipopolysaccharide group (P < 0.05). Serum free fatty acid concentrations were decreased in animals exposed to HEC. Animals receiving lipopolysaccharide showed an increase in pulmonary pressure (P < 0.001), but otherwise, there were no major changes in pulmonary or hemodynamic function. Neutrophil function was impaired after lipopolysaccharide administration.     

Effects of antibodies against octreotide in two patients with acromegaly

Two patients developed specific IgG antibodies against octreotide after 2-3 years' treatment for acromegaly with this long acting somatostatin analogue. The presence of these antibodies reduced the plasma disappearance rate of total extractable octreotide by 60 and 80% respectively. When compared to that of non-immune acromegalic patients, the plasma half-life of octreotide in these two patients was 300 and 450 vs 110 min in those with no detectable octreotide antibodies. The sole observed consequence of the immunization was a marked prolongation of the interval of maximum GH inhibition from a mean of 5 to 8 and 10 h in the two patients described after octreotide injection.     

Targets and tactics: the relative importance of HbA1c,fasting and postprandial plasma glucose levels to glycaemic control in type 2 diabetes

Background: The incidence of type 2 diabetes is reaching pandemic proportions, impacting patients and healthcare systems across the globe. Evidence suggests that a majority of patients are not achieving recommended blood glucose targets resulting in an increased risk of micro‐ and macro‐vascular complications. Aim: To review literature on the significance of glycosylated haemoglobin (HbA_1c), fasting plasma glucose (FPG) and postprandial plasma glucose (PPG), their inter‐relationships and relative importance in the treatment of diabetes, and to provide practical guidance on effective monitoring of patients. Methods: Clinical guidelines on diabetes management and clinical and preclinical studies of glycaemic control identified through a publications database search were reviewed. Results: Glycaemic control remains fundamental to the successful management of diabetes. HbA_1c is the gold standard measure of glycaemic control but recent evidence suggests that postmeal hyperglycaemia also plays an important role in the aetiology of diabetes‐associated complications and control of PPG levels is vital to the achievement of recommended HbA_1c targets. Conclusions: The call for action on type 2 diabetes has never been more compelling; with a clear focus on strategies for glycaemic control, the impact of the diabetes pandemic can be limited.     

The metabolic and hormonal response to acute normoglycaemia in type 1 (insulin-dependent) diabetes: Studies with a glucose controlled insulin infusion system (artificial endocrine pancreas)

Summary Twelve insulin deficient Type 1 (insulin-dependent) diabetic subjects were studied over an 11 1/2 h period during both subcutaneous insulin therapy and closed loop insulin delivery, using a glucose controlled insulin infusion system (Biostator) programmed to maintain normoglycaemia. Results were compared with those from 21 age and weight-matched normal subjects. Using the Biostator, normoglycaemia was achieved in all diabetic subjects within 3.5 h and normal profiles maintained thereafter. Blood metabolite and hormone values were evaluated during the subsequent 8 h normoglycaemic period. Subcutaneous therapy resulted in abnormal glucose levels throughout the study period (mean 8 h value 8.3±0.7 compared with 5.6±0.3 mmol/l on feedback control and 5.5.±0.1 mmol/l in normal subjects). The mean value of lactate and pyruvate over the final 8 h period was 25% higher in diabetic patients than in normal subjects with no difference between the two insulin treatments (blood lactate: 0.94±0.04 on subcutaneous insulin, 0.91±0.04 on feedback control and 0.74±0.03 mmol/l in control subjects). The pre-prandial peaks of blood glycerol and plasma non-esterified fatty acids were significantly decreased or absent during both feedback control and subcutaneous therapy in comparison with the normal subjects, whereas after the midday and evening meals, total ketone body levels were significantly higher in the diabetic patients. Peripheral serum free insulin levels were two-to fourfold greater in the diabetic than in the normal subjects. There were no significant differences between levels in diabetic patients receiving subcutaneous insulin or on the Biostator. Glucose turnover (1600–1800 h) was normal on feedback control (1.41±0.20 versus 1.55±0.18 mg · kg^-1 · min^-1 in the normal subjects) but was significantly decreased during subcutaneous insulin (1.04±0.09 mg · kg^-1 · min^-1). There was, in addition, a decrease in glucose recycling during both subcutaneous insulin therapy and feedback control in the diabetic subjects. These data suggest that although fine control of glucose metabolism both in terms of circulating concentrations and rates of production can be achieved by feedback-control, insulin infusion by the peripheral route is associated with significant metabolic abnormalities, at least in the short term. Longer term studies and examination of portal insulin delivery seem warranted.     

Estradiol supplementation modulates growth hormone (GH) secretory-burst waveform and recombinant human insulin-like growth factor-I-enforced suppression of endogenously driven GH release in postmenopausal women

The present study tests the mechanistic postulate that estrogen confers resistance to negative feedback by systemic IGF-I. To this end, eight postmenopausal women received a constant iv infusion of recombinant human (rh)IGF-I (10 micro g/kg.h x 6 h) and saline in randomized order on the 10th day of supplementation with oral estradiol (E(2)) and placebo (Pl). GH secretion was quantitated by 10-min blood sampling, immunochemiluminometry assay, and deconvolution analysis. Administration of E(2) compared with Pl followed by saline infusion: 1) stimulated pulsatile GH secretion ( micro g/liter.6 h), viz., 12 +/- 3.3 (Pl) and 18 +/- 4.6 (E(2)) (mean +/- SEM, paired comparison, P < 0.05); 2) halved the time latency (min) to achieve peak GH secretion after GHRH injection, 24 +/- 2.2 (Pl) and 12 +/- 2.1 (E(2)) (P < 0.01); and 3) did not alter the mass of GH secreted ( micro g/liter) in response to a maximally effective dose of GHRH, 30 +/- 7.2 (Pl) and 37 +/- 11 (E(2)). Exposure to E(2) compared with Pl followed by rhIGF-I infusion: 1) accelerated the rate of decline of GH concentrations by 3.3-fold, viz., absolute slope ( micro g/liter.1000 min), 3.8 (range, 2.5-5.0) (Pl) and 12 (range, 10-14) (E(2)) (P < 0.001); 2) augmented the algebraic decrement in GH concentrations ( micro g/liter) enforced by rhIGF-I infusion, 0.73 +/- 0.21 (Pl) and 1.6 +/- 0.25 (E(2)) (P < 0.01); 3) halved the time delay (min) to peak GHRH-induced GH secretion, 20 +/- 1.2 (Pl) vs. 10 +/- 1.3 (E(2)) min (P < 0.01). In contradistinction, E(2) did not alter: 1) the capability of rhIGF-I to suppress GHRH-stimulated GH secretory burst mass significantly, viz., by 50 +/- 8% (Pl) and 52 +/- 14% (E(2)) (P < 0.05 each vs. saline); 2) the hourly rate of rise of infused (total) IGF-I concentrations; and 3) total and ultrafiltratably free IGF-I concentrations ( micro g/liter) attained at the end of the two rhIGF-I infusions. In summary, compared with Pl, E(2) supplementation in postmenopausal women: 1) amplifies endogenously driven GH secretory-burst mass; 2) initiates rapid onset of GHRH-stimulated GH release; and 3) potentiates IGF-I-dependent suppression of unstimulated GH concentrations. Based upon companion modeling data, we postulate that E(2) facilitates the upstroke and IGF-I enforces the downstroke of high-amplitude GH secretory bursts in estrogen-replete individuals.     

Cotreatment of acromegaly with a somatostatin analog and a growth hormone receptor antagonist

CONTEXT: Pegvisomant is a GH receptor antagonist that blocks the peripheral actions of GH in acromegaly. Pegvisomant, in contrast to somatostatin (SMS) analogs, does not suppress the activity of the GH-producing adenoma. OBJECTIVE: We assessed the effects of cotreatment with pegvisomant and SMS in acromegaly on GH secretion, IGF-I levels, and glucose tolerance. DESIGN, PATIENTS, AND INTERVENTIONS: Eleven patients with persistent disease despite previous therapy underwent the following fixed treatment algorithm: 1) on SMS therapy, 2) off therapy for 2 months, 3) 6-wk treatment with 10 mg/d pegvisomant, 4) 6-wk treatment with 15 mg/d pegvisomant, and 5) 3-month treatment with 15 mg pegvisomant plus SMS. Blood was sampled in the fasting state and during an oral glucose tolerance test. RESULTS: Total serum IGF-I levels (micrograms per liter) decreased after pegvisomant, but the lowest levels were obtained with cotreatment [458 +/- 67 (SMS), 562 +/- 78 (active), 376 +/- 51 (10 mg), 269 (15 mg), 195 +/- 24 (combined) (P < 0.0001)]. Free and bioactive IGF-I changed in a similar pattern. Steady-state pegvisomant levels (micrograms per liter) were obtained, but SMS cotreatment increased pegvisomant levels by 20% (P = 0.02) [2631 +/- 616 (10 mg), 6536 +/- 1413 (15 mg), 8030 +/- 1914 (combined)]. Pegvisomant increased endogenous GH levels (micrograms per liter), which was countered by SMS cotreatment [5.1 +/- 1.3 (SMS), 8.9 +/- 2.9 (active), 14.6 +/- 4.9 (10 mg), 19.7 +/- 6.5 (15 mg), 11.8 +/- 2.8 (combined) (P < 0.01)]. Plasma glucose levels (millimoles per liter) were highest during SMS and lowest during pegvisomant 15 mg [2-h oral glucose tolerance test: 10.3 +/- 0.7 (SMS), 8.9 +/- 0.7 (active), 7.2 +/- 0.7 (10 mg), 6.5 +/- 0.5 (15 mg), 8.0 +/- 0.8 (combined) (P = 0.02)]. CONCLUSIONS: Dual blockade of the GH axis with pegvisomant and a SMS analog is feasible in acromegaly.     

Ghrelin immunoreactivity in human plasma is suppressed by somatostatin

OBJECTIVE: Ghrelin was recently identified as a specific endogenous ligand for the growth hormone secretagogue receptor (GHS-R). This new hormone was isolated from rat and human stomach and was reported to circulate in human plasma, but the regulation and physiological significance of ghrelin in humans have not been clarified. The present study was undertaken to test the following hypotheses: (1) prolonged fasting, which is known to stimulate GH secretion, is associated with changes in ghrelin immunoreactivity; (2) somatostatin in the systemic circulation regulates ghrelin secretion; and (3) GH affects ghrelin levels. DESIGN AND PATIENTS: The study population included normal subjects investigated on three occasions (fasting alone, fasting and somatostatin infusion +/- GH); GH-deficient adults investigated after 12 and 36 h of fasting +/- GH, as well as patients with active acromegaly before and after somatostatin analogue treatment. RESULTS: Somatostatin infusion lowered ghrelin levels 70-80% (P < 0.0001), whereas continued fasting +/- GH did not significantly affect ghrelin levels. In active acromegaly, suppression of plasma ghrelin levels was recorded after a single subcutaneous octreotide injection as well as during prolonged administration of slow-release octreotide. CONCLUSIONS: (1) Amplification of GH release during prolonged fasting is not caused by an increase in ghrelin immunoreactivity, (2) systemic somatostatin suppresses plasma ghrelin levels independently of GH status, and (3) the feasibility of measuring ghrelin in the circulation provides an opportunity for studying the interaction between hormones and nutrition.     

Normalization of fasting hyperglycaemia by exogenous glucagon-like peptide 1 (7-36 amide) in Type 2 (non-insulin-dependent) diabetic patients

Summary Glucagon-like peptide 1 (GLP-1) (7-36 amide) is a physiological incretin hormone that is released after nutrient intake from the lower gut and stimulates insulin secretion at elevated plasma glucose concentrations. Previous work has shown that even in Type 2 (non-insulin-dependent) diabetic patients GLP-1 (7-36 amide) retains much of its insulinotropic action. However, it is not known whether the magnitude of this response is sufficient to normalize plasma glucose in Type 2 diabetic patients with poor metabolic control. Therefore, in 10 Type 2 diabetic patients with unsatisfactory metabolic control (HbA_lc 11.6±1.7%) on diet and sulphonylurea therapy (in some patients supplemented by metformin or acarbose), 1.2 pmol ×kg^–1×min^–1 GLP-1 (7-36 amide) or placebo was infused intravenously in the fasting state (plasma glucose 13.1±0.6 mmol/l). In all patients, insulin (by 17.4±4.7 nmol ×1^–1×min; p=0.0157) and C-peptide (by 228.0±39.1 nmol×1^–1×min; p=0.0019) increased significantly over basal levels, glucagon was reduced (by -1418±308 pmol ×1^–1×min) and plasma glucose reached normal fasting concentrations (4.9±0.3 mmol/l) within 4 h of GLP-1 (7-36 amide) administration, but not with placebo. When normal fasting plasma glucose concentrations were reached insulin returned towards basal levels and plasma glucose concentrations remained stable despite the ongoing infusion of GLP-1 (7-36 amide). Therefore, exogenous GLP-1 (7-36 amide) is an effective means of normalizing fasting plasma glucose concentrations in poorly-controlled Type 2 diabetic patients. The glucose-dependence of insulinotropic actions of GLP-1 (7-36 amide) appears to be retained in such patients.