Correlates of fractures in elderly, diabetic outpatients

It is widely recognized that patients presenting diabetes are at increased risk for fractures. In a retrospective case-control study, 101 cases were selected from medical charts of outpatients older than 70 with diabetes mellitus and a fracture within the past 5 years. Glycosylated hemoglobin (HbA1c) had been measured within 4 months around the assessment. Each case was matched for sex and age with one control, diabetic patient with no fracture. HbA1c level was similar in both groups. Patients with fractures presented significantly lower BMIs than controls, and had a higher rate of declared osteoporosis and comorbidity. A small number of cases were using vitamin D supplements while more were treated with benzodiazepine, opiates and Selective serotonin reuptake inhibitors (SSRI). This study suggests that, rather than the tight control of blood glucose, other factors such as medication and comorbidity could be associated with fracture risk in elderly diabetics.

Comparative pharmacoscintigraphic and pharmacokinetic evaluation of two new formulations of inhaled insulin in type 1 diabetic patients

In this open, single-dose study, we compared the lung deposition and bioavailability of two newly developed insulin formulations for pulmonary delivery. Twelve type 1 diabetic patients were administered the two insulin products (2 U/kg b.w.), which had been radiolabelled with (99m)Tc. The formulations were either microparticles of insulin without excipients (F1) or lipid-coated insulin microparticles (F2). Lung deposition was assessed by γ-scintigraphy imaging performed immediately after administration. Bioavailability was evaluated by quantifying serum insulin levels over a period of 6 h. Lung deposition was found to be 50 ± 9% and 24 ± 8% for the F1 and F2 formulations, respectively. The insulin AUC₀₋₃₆₀ ratio of F1/F2 was 188%, which was consistent with scintigraphic imaging. The concordance between imaging and biological results suggests that the lower bioavailability of F2 is due to its lower lung deposition and not to a reduced absorption into the blood stream. Additional in vitro experiments indicated that the lower performance of F2 was most probably related to a lower disaggregation efficiency of the powder when administered at a sub-optimal flow rate. The two formulations showed interesting pharmacokinetic profiles (T(max) of 26 and 16 min for F1 and F2, respectively) that mimic the physiological insulin secretion pattern. The bioavailability of the developed formulations was within the range of other DPI insulin formulations that have reached the final stages of clinical development.

Combined pancreatic and kidney transplantation: en bloc retrieval and transplantation--a new surgical technique

We designed and performed on two patients a new surgical procedure of en bloc kidney and pancreatic transplantation. The liver, pancreas and kidneys were removed en bloc in the donor. On the bench, the liver and the left kidney were separated from the bloc, leaving the pancreas and the right kidney for combined kidney and pancreatic transplantation. The portal vein was divided near to the emergence of the splenic vein. The coeliac axis was taken with an aortic patch. The left renal vein was cut at its entrance to the inferior vena cava (IVC) and the left renal artery was taken with an aortic patch. Reconstruction of the pancreatic vessels was performed with a double anastomosis: the portal vein was anastomosed to the hole in the IVC resulting from the section of the left renal vein and the splenic artery was anastomosed to the hole in the aorta resulting from the section of the left renal artery. The proximal ends of the aorta and IVC were closed with running sutures. In the recipient, the iliac vessels on the right side were dissected. Anastomosis of the distal part of the aorta and the IVC was performed with the right iliac vessels. Duodenocystostomy and reimplantation of the ureter were done according to the usual techniques. This new surgical technique allowed an easy vascular reconstruction of the pancreatic vessels. In the recipient, only one side was used for renal and pancreatic transplantation. Moreover, the length of the transplant procedure was significantly reduced.

Ambulatory blood pressure and neuroendocrine control after diet-assisted gastric restrictive surgery

BACKGROUND

Long-term weight control after conventional diet is disappointing but may be improved when diet is assisted by gastric restrictive surgery (GRS).

OBJECTIVE

To determine the effects of GRS on ambulatory blood pressure (ABP) and neuroendocrine BP control in 28 morbidly obese subjects.

METHODS

A BP and heart rate were recorded every 10 min for 25 h before and 4 months after GRS. Effects of marked reductions in body weight on the renin-angiotensinaldosterone system, on plasma insulin and on sympathetic activity were also determined.

RESULTS

Body mass index decreased from 43 +/- 1 to 34 +/- 1 kg/m2 and systolic (S) BP decreased by 7 +/- 2 mmHg during daytime (P=0.01) and by 8 +/- 3 mmHg during the night (P=0.02). Pulse pressure, a marker of reduced arterial compliance, decreased by 5 +/- 1 mmHg throughout the 24 h period (P < 0.001). Diastolic BP remained unchanged. Heart rate decreased more during the night (-13 +/- 2 bpm, P<0.0001) than during daytime (-5 +/- 2 bpm, P=0.03). Reductions in SBP were largest in subjects with highest initial BP values (r = -0.63, P<0.001) but were unrelated to weight loss. GRS decreased fasting glycaemia, plasma insulin, plasma C peptide and 24 h urine sodium (n=20) and noradrenaline (n=19) excretion (P<0.01).

CONCLUSIONS

Diet-assisted GRS favourably affects neuroendocrine BP control in obese patients. Reductions in sodium intake, insulin levels and sympathetic tone combined with possible improvements in arterial compliance induce persistent 24 h reductions in SBP and pulse BP. Reductions in BP are largest in subjects with highest initial BP values and are unrelated to the amount of weight loss, thereby emphasizing the importance of even moderate reductions in weight on BP control.

Effect of fasting on the intracellular metabolic partition of intravenously infused glucose in humans

The effects of fasting on the pathways of insulin-stimulated glucose disposal were explored in three groups of seven normal subjects. Group 1 was submitted to a euglycemic hyperinsulinemic clamp ( approximately 100 microU/ml) after both a 12-h and a 4-day fast. The combined use of [3-(3)H]- and [U-(14)C]glucose allowed us to demonstrate that fasting inhibits, by approximately 50%, glucose disposal, glycolysis, glucose oxidation, and glycogen synthesis via the direct pathway. In group 2, in which the clamp glucose disposal during fasting was restored by hyperglycemia (155 +/- 15 mg/dl), fasting stimulated glycogen synthesis (+29 +/- 2%) and inhibited glycolysis (-32 +/- 3%) but only in its oxidative component (-40 +/- 3%). Results were similar in group 3 in which the clamp glucose disposal was restored by a pharmacological elevation of insulin ( approximately 2,800 microU/ml), but in this case, both glycogen synthesis and nonoxidative glycolysis participated in the rise in nonoxidative glucose disposal. In all groups, the reduction in total carbohydrate oxidation (indirect calorimetry) induced by fasting markedly exceeded the reduction in circulating glucose oxidation, suggesting that fasting also inhibits intracellular glycogen oxidation. Thus prior fasting favors glycogen retention by three mechanisms: 1) stimulation of glycogen synthesis via the direct pathway; 2) preferential inhibition of oxidative rather than nonoxidative glycolysis, thus allowing carbon conservation for glycogen synthesis via the indirect pathway; and 3) suppression of intracellular glycogen oxidation.

Metabolic effects of short-term elevations of plasma cortisol are more pronounced in the evening than in the morning

To determine whether elevations of cortisol levels have more pronounced effects on glucose levels and insulin secretion in the evening (at the trough of the daily rhythm) or in the morning (at the peak of the rhythm), nine normal men each participated in four studies performed in random order. In all studies, endogenous cortisol levels were suppressed by metyrapone administration, and caloric intake was exclusively under the form of a constant glucose infusion. The daily cortisol elevation was restored by administration of hydrocortisone (or placebo) either at 0500 h or at 1700 h. In each study, plasma levels of glucose, insulin, C-peptide, and cortisol were measured at 20-min intervals for 32 h. The initial effect of the hydrocortisone-induced cortisol pulse was a short-term inhibition of insulin secretion without concomitant glucose changes and was similar in the evening and in the morning. At both times of day, starting 4-6 h after hydrocortisone ingestion, glucose levels increased and remained higher than under placebo for at least 12 h. This delayed hyperglycemic effect was minimal in the morning but much more pronounced in the evening, when it was associated with robust increases in serum insulin and insulin secretion and with a 30% decrease in insulin clearance. Thus, elevations of evening cortisol levels could contribute to alterations in glucose tolerance, insulin sensitivity, and insulin secretion.

Inhibition of lipolysis stimulates whole body glucose production and disposal in normal postabsorptive subjects

The role played by circulating free fatty acids (FFA) and fat oxidation in the regulation of whole body glucose production and uptake in the basal state is still a matter of debate. This question was analyzed in nine normal overnight fasted volunteers in whom glucose kinetics ([3-3H]glucose infusion) and substrate oxidation rates (indirect calorimetry) were measured during 10.5 h both under placebo conditions and during experimental antilipolysis induced by Acipimox given orally during the last 8 h of the study. During the last 2 h of the tests, the following mean changes (delta) from baseline were recorded in Acipimox vs. placebo studies: delta FFA, -0.26 +/- 0.08 vs. +0.29 +/- 0.06 mmol/L (P < 0.001); delta glucose, -12 +/- 2 vs. -12 +/- 1 mg/dL (P > 0.05); delta glucose production, +16 +/- 5 vs. -15 +/- 3 mg/min (P < 0.001); delta C peptide, -1.11 +/- 0.10 vs. -0.66 +/- 0.10 ng/mL (P < 0.001); delta glucagon, +64 +/- 25 vs. +21 +/- 9 pg/mL (P < 0.05); delta GH, +37 +/- 9 vs. +4 +/- 2 ng/mL (P < 0.007); delta cortisol, +37 +/- 25 vs. -30 +/- 26 ng/mL (P < 0.04). Acipimox inhibited fat oxidation (-18 +/- 4 vs. +19 +/- 4 mg/min; P < 0.001) and enhanced carbohydrate oxidation (+18 +/- 8 vs. -24 +/- 11 mg/min; P < 0.02). Protein catabolism calculated over the 8-h study period was significantly stimulated (+5.7 +/- 2.5 vs. -1.9 +/- 1.7 g/8 h; P < 0.02). During the Acipimox studies, the increased protein breakdown could theoretically account for about 75% of the increased glucose production. Thus, contrary to current opinion, FFA suppression stimulates glucose production and whole body glucose disposal in normal overnight fasted subjects.

Assessment of whole-body composition with dual-energy x-ray absorptiometry

Dual-energy x-ray absorptiometry (DXA) allows noninvasive direct measurement of the three major components of body composition: lean body mass (LBM), fat body mass (FBM), and bone mineral body mass (BBM). To study the accuracy and short-term and long-term precision of body composition measurements, the authors measured body composition with DXA in 60 healthy young adults. Independent measurement of LBM (LBMK-40), obtained from the determination of the whole-body content of potassium-40 with a whole-body scintillation detector, was highly correlated with LBM determined with DXA (LBMDXA) (LBMK-40 = 1.069.LBMDXA,R2 = .996). Assessment of body composition in 10 patients with acquired immunodeficiency syndrome (AIDS) and 10 patients with cystic fibrosis was performed with DXA. The AIDS patients showed a marked decrease in LBM, while in patients with cystic fibrosis, LBM and BBM were decreased. DXA measurements of body composition appeared accurate and precise enough to be of clinical relevance in detecting specific alterations of body composition.

Mechanisms of starvation diabetes: a study with double tracer and indirect calorimetry

To analyze the mechanisms of fasting-induced glucose intolerance, glucose metabolism was studied before and after the ingestion of 75 g glucose in 24 normal subjects fasted for either 14 h (n = 12) or 4 days (n = 12). The techniques included intravenous infusion of [6-3H]glucose and oral administration of [1-14C]glucose combined with indirect calorimetry. Compared with the controls, the starved subjects exhibited the following differences in glucose metabolism during the 5 h after glucose ingestion. 1) Mean incremental levels were fourfold higher for glucose and 40% higher for insulin. 2) Absorption of oral glucose was delayed and prolonged, but total amount reaching systemic circulation in 5 h was identical in the two groups (approximately 63 g). 3) Suppression of hepatic glucose output was reduced (-12 +/- 1 vs. -22 +/- 2 g). 4) Consequently, the increment in peripheral appearance of total glucose (exogenous plus endogenous) was augmented (+ 52 +/- 2 vs. +41 +/- 2 g). 5) Mean glucose clearance increased significantly less (+28 +/- 7 vs. +96 +/- 10 ml/min). 6) Oxidation of oral glucose was reduced (9 +/- 2 vs. 36 +/- 3 g), and nonoxidative disposal (presumably storage) was enhanced (56 +/- 2 vs. 36 +/- 3 g) in the presence of an elevated fat oxidation (35 +/- 2 vs. 22 +/- 4 g). Thus the alterations in glucose homeostasis responsible for the starvation-induced glucose intolerance are located both at the splanchnic (hepatic) and peripheral levels.

Hormonal and metabolic changes induced by an isocaloric isoproteinic ketogenic diet in healthy subjects

The effects of a 4-day isocaloric isoprotenic dietary replacement of carbohydrate by fats were studied in six healthy subjects, the experimental diet being preceded and followed by a 3-day period of balanced diet. During the ketogenic regimen, the concentrations of fat derived substrates (free fatty acids, glycerol and 3-hydroxybutyrate) rose significantly and glucose levels decreased by 16.5 +/- 3.2% (mean +/- SEM). The hormonal pattern switched towards a catabolic mode with a fall in insulin levels (-44.0 +/- 6.3%) and a rise in glucagon concentration (+39.0 +/- 10.4%). A significant fall in triiodothyronine and rise in reverse triiodothyronine were observed, while thyroxine levels remained unchanged. The average levels of the most important gluconeogenic amino acids (alanine, glutamine, glycine, serine and threonine) were reduced by 8-34% while those of the branched chain amino acids increased by more than 50%. Since these changes reproduce those observed after a few days of total fasting, we suggest that it is the carbohydrate restriction itself which is responsible for the metabolic and hormonal adaptations of brief fasting.

Changes induced by exercise in rates of turnover and oxidation of ketone bodies in fasting man

Seven normal subjects fasted for 3 days were exercised for 30 min on a bicycle ergometer at 60 +/- 30% (mean +/- SE) of their maximal aerobic capacity. Rates of transport and oxidation of ketone bodies were determined at rest and during exercise using a primed constant infusion of [14C]acetoacetate. During the initial 7.5 min of exercise, ketone concentration abruptly decreased (-19.4 +/- 3.1%; P less than 0.001) as the result of a 22.2 +/- 7.0% reduction (P less than 0.05) in ketone production rate (Ra) and a 30.4 +/- 7.5% increase (P less than 0.01) in the rate of uptake (Rd) of ketones. As work progressed, blood ketones continued to fall slowly until the 15th min of exercise and thereafter plateaued at a level which was 21.9 +/- 4.1% lower (P less than 0.005) than resting values. During this apparent new steady state, both Ra and Rd were below control values but tended to be equal and to return simultaneously to their preexercise level. The metabolic clearance rate was increased throughout the entire period of exercise, the rise being more marked during the initial 7.5 min (+40.7 +/- 7.5%; P less than 0.01) than at later periods (+19.0 +/- 7.4%; P less than 0.05). Exercise greatly enhanced ketone oxidation which became virtually complete; despite this, the %CO2 derived from ketones, which averaged 17.6 +/- 1.6% at rest, decreased to 10.1 +/- 0.6% (P less than 0.01) after 30 min of work. This indicates that even during the hyperketonemia of fasting, the increased energy needs related to exercise are met primarily by fuels other than ketones.