The role of autoregulation of the hepatic glucose production in man. Response to a physiologic decrement in plasma glucose

In man, a decrease in plasma glucose concentration results in a compensatory increase in hepatic glucose release. Studies in vitro have suggested that a low glucose concentration per se may directly stimulate hepatic glucose release, an effect often referred to as autoregulation. Whether autoregulation occurs in man in response to a physiologic decrement in blood glucose is not known. Therefore, seven healthy, nonobese subjects were studied on two occasions to determine the role of autoregulation in mediating the increase in glucose production that accompanies a physiologic decrement in plasma glucose concentration. On both occasions, plasma glucose concentrations were clamped successively at 95, 65, and 95 mg/dl for 2 h each. Insulin (approximately 14 microU/ml) and glucagon (approximately 70 pg/ml) were maintained constant on both occasions by an infusion of somatostatin and insulin. Phentolamine and propranolol also were infused on one occasion to produce combined alpha- and beta-adrenergic blockade. In the absence of adrenergic blockade, glucose production increased by approximately 1.3 mg/kg X min when the plasma glucose concentration was decreased from 95 to 65 mg/dl and decreased by approximately 1.5 mg/kg X min when glucose was increased from 65 to 95 mg/dl. In the presence of adrenergic blockade, the increase and decrease in glucose production averaged 0 and 0.5 mg/kg X min, respectively, representing 70-100% inhibition. We conclude that, in the presence of low physiologic insulin concentrations, autoregulation is not a major contributor to the hepatic response to a physiologic decrement in plasma glucose concentration in man.     

Coping and adjustment in men with prostate cancer: a systematic review of qualitative studies

Purpose

Prostate cancer (PCa) is one of the most common forms of cancer amongst males. Men’s coping responses are an important determinant of functioning and adjustment to this disease. Previous qualitative research exists in this area, but the current review sought to systematically review and summarise these studies.

Methods

A systematic review was conducted to identify studies concerned with men’s coping strategies in their attempts to live with PCa. A search of relevant electronic databases was conducted to identify studies that met inclusion criteria for this review. Methodological quality assessment was also undertaken for each included study.

Results

One hundred twenty-one publications were identified for initial screening, and 18 studies were included in the review. A total of five coping strategy categories or ‘meta-themes’ were identified across included studies. These categories were labelled ‘avoidance, minimisation, and withdrawal’, ‘directing cognition and attention’, ‘reframing masculinity and seeking support’, ‘retain pre-illness identity and lifestyle’, and ‘symptom/side-effect management’.

Conclusions

A range of coping strategies were reported by men with PCa. Some of these strategies appear to be partially influenced by gender roles and masculinities. Coping meta-themes reported in this review have also been found in other research on men’s coping. Strategies relating to flexible interpretation of gender roles/masculinities may be a particularly relevant category of coping responses due to the hypothesised beneficial impact of flexibility on psychological well-being.

Implications for cancer survivors

PCa survivors utilise a range of coping strategies, and the types of strategies used may have implications for men’s well-being. The ability to be flexible in both coping responses used, and in the view of oneself as a man may be particularly important skills in meeting the challenges associated with this disease.

     

Risky behavior in teens with cystic fibrosis or sickle cell disease: a multicenter study

OBJECTIVE: To determine the prevalence and age of onset of common risky behaviors such as smoking and sexual activity in teens with cystic fibrosis and those with sickle cell disease and to compare their behaviors with those of adolescents in the general population. DESIGN: Survey. SETTING: All five major pediatric tertiary care centers in North Carolina (study participants with sickle cell disease or cystic fibrosis) and North Carolina public schools (comparison population). PARTICIPANTS: Three hundred twenty-one adolescents with cystic fibrosis or sickle cell disease aged 12 to 19 years (mean age, 15.6 years; 49% female). Demographically matched comparison teens for each group were selected from 2760 in-school adolescents (mean age, 16.0 years; 51% female). MAIN OUTCOMES MEASURES: Prevalence of tobacco and marijuana use, alcohol use, sexual intercourse, sexually transmitted diseases, seat belt use, weapon carrying, and age of onset of these behaviors. RESULTS: Chronically ill teens reported significantly less lifetime and current use of tobacco, marijuana, and alcohol; less sexual intercourse; less weapon carrying, less drunk driving, and more seat belt use than their peers. Nonetheless, 21% of the teens with cystic fibrosis and 30% of those with sickle cell disease had smoked; sexual intercourse was reported by 28% and 51%, respectively. Age of onset of these behaviors was frequently older for the chronically ill teens. CONCLUSION: Teens with cystic fibrosis or sickle cell disease took more potentially damaging health risks than might be expected, although the prevalence was lower than reported by their peers. Future longitudinal studies should examine the relationships between chronic illness, physical and psychosocial maturation, and risky behavior. Screening for psychosocial issues, including risky behaviors, should be incorporated into the routine health care of chronically ill teens.     

Contribution of plasma galactose and glucose to milk lactose synthesis during galactose ingestion

We have previously demonstrated that plasma glucose contributed 80% in the fed and 60% in the fasted state to lactose synthesis in humans, and de novo synthesis in the breast contributing to both the glucose and galactose moieties accounted for the remaining 20% and 40%, respectively, of lactose. The present study was conducted to determine, in lactating women, whether oral galactose is directly incorporated from plasma galactose into glucose and galactose in milk lactose or via conversion of galactose to glucose in the liver. Six healthy exclusively breast-feeding women (30 +/- 2 yr) (mean +/- SE) ingested galactose at 22 micromol x kg-1 x min-1 for 9 h after an overnight fast during infusion of [6,6-2H2]glucose and [1-13C]galactose. We observed that 69 +/- 6% of glucose and 54 +/- 4% of galactose in lactose were derived directly from plasma glucose, whereas 7 +/- 2% and 12 +/- 2% of glucose and galactose in lactose, respectively, were derived directly from plasma galactose. De novo synthesis of glucose and galactose via hexoneogenesis accounted for 25 +/- 8% and 35 +/- 6%, respectively. We conclude that during ingestion of galactose the contribution from plasma glucose to glucose and galactose in lactose was similar to that of a short-term fasting, but part of the de novo synthesis of glucose and galactose in the breast was replaced by direct uptake of galactose.     

Insulin and glucose as modulators of the amino acid-induced glucagon release in the isolated pancreas of alloxan and streptozotocin diabetic rats.

The hyperglucagonemia that occurs in vivo in animals made diabetic with alloxan or streptozotocin is not suppressed by high glucose but is suppressed by exogenous insulin. These observations together with other studies suggested that insulin-dependent glucose transport and metabolism by the alpha-cells serves as the primary mechanism controlling glucagon secretion. This hypothesis was tested in the present investigation. The possible interactions between glucose, insulin, and a mixture of 20 amino acids at physiological proportions were examined in the isolated-perfusin diabetic rats. Release of insulin and glucagon were used as indicators of theta-cell and alpha-cell function. According to rigid criteria the diabetic animals entering the study were severely diabetic. It was found that in vitro: (a) basal glucagon release (measured in the absence of an alpha-cell stimulus or inhibitor) was extremely low, even lower (i.e. 10%) than the basal rates seen in controls; (b) the alpha-cells of alloxanized- and streptozotocin-treated rats responded with a biphasic glucagon release to stimulation by an amino acid mixture; (c) this alpha-cell response was reduced after both streptozotocin and alloxan; (d) glucose at 5 mM was a potent inhibitor of amino acid-induced glucagon secretion in both types of experimental diabetes; (e) in alloxan diabetes alpha-cell stimulation by amino acids can be curbed by exogenous insulin, whereas glucagon secretion by the perfused pancreas of streptoxotocin diabetic rats appeared to be resistant to insulin action. The data indicate that the modulation of glucagon secretion by glucose in vitro is indipendent of insulin and that other unknown factors extrinsic to the pancreatic islets are responsible for the hyperglucagonemia observed in vivo.     

Treatment of diabetic ketoacidosis in children and young adults

The medical emergency of diabetic ketoacidosis is a particular problem for children with insulin-dependent diabetes because it is frequently associated with their initial presentation. Subsequent episodes can be prevented with proper use of personal glucose monitoring. The pathophysiology and diagnosis of diabetic ketoacidosis are reviewed, and a framework for the management of this complication in children is provided.     

Evaluation of factor VIII-rich cryoprecipitate and the plasma fibronectin-rich, heparin-precipitable fraction prepared from single- donor plasma units

A plasma fibronectin-rich component was prepared by heparin-induced 4 degrees C precipitation of fresh or stored (21 days at 4 degrees C), single-donor plasma. The recovery of plasma fibronectin was 45 percent at a concentration of 0.05 mg heparin per ml (7.5 units/ml) and 75 percent at 0.1 mg per ml (15 units/ml). The biologic activity of plasma fibronectin, as assessed by the spreading of Chinese hamster ovary cells or attachment of monocytes to gelatin-coated surfaces, was similar to that of plasma fibronectin concentrates made from fresh or stored plasma. Only 20 to 30 percent of the factor VIII activity in fresh plasma was recovered in cryoprecipitate produced after the heparin-induced precipitate containing fibronectin was removed. Cryoprecipitate prepared from the supernatant plasma that remains after heparin-induced cold precipitation in the presence of CaCl2 (5 mM) contained approximately 50 percent less factor VIII. The relatively low recovery of factor VIII in cryoprecipitate prepared from fibronectin-depleted plasma makes cryoprecipitation an unsuitable method of producing fibronectin-rich and factor VIII-rich components effectively from a single unit of fresh plasma. However, heparin-induced cold precipitation provides an efficient method for preparing plasma fibronectin concentrates from small plasma pools or single units of stored or fresh plasma.