The artificial pancreas: two alternative approaches to achieve a fully closed-loop system with optimal glucose control.

INTRODUCTION: Diabetes mellitus type 1 is a chronic disease that implies mandatory external insulin delivery. The patients must monitor their blood glucose levels and administer appropriate insulin boluses to keep their blood glucose within the desired range. It requires a lot of time and endeavour, and many patients struggle with suboptimal glucose control despite all their efforts. MATERIALS AND METHODS: This narrative review combines existing knowledge with new discoveries from animal experiments. DISCUSSION: In the last decade, artificial pancreas (AP) devices have been developed to improve glucose control and relieve patients of the constant burden of managing their disease. However, a feasible and fully automated AP is yet to be developed. The main challenges preventing the development of a true, subcutaneous (SC) AP system are the slow dynamics of SC glucose sensing and particularly the delay in effect on glucose levels after SC insulin infusions. We have previously published studies on using the intraperitoneal space for an AP; however, we further propose a novel and potentially disruptive way to utilize the vasodilative properties of glucagon in SC AP systems. CONCLUSION: This narrative review presents two lesser-explored viable solutions for AP systems and discusses the potential for improvement toward a fully automated system: A) using the intraperitoneal approach for more rapid insulin absorption, and B) besides using glucagon to treat and prevent hypoglycemia, also administering micro-boluses of glucagon to increase the local SC blood flow, thereby accelerating SC insulin absorption and SC glucose sensor site dynamics.

Detection of tissue kallikrein in the bronchoalveolar lavage fluid of asthmatic subjects.

Kininogenase activity was detected by cleavage of radiolabeled substrate (125I-high molecular weight kininogen [HMWK]) in 22 of 24 bronchoalveolar lavage (BAL) fluid samples from 17 asthmatics who either responded to aerosolized allergen challenge or had symptoms of active asthma. In contrast, six of seven normal controls lacked enzymatic activity. Levels of free immunoreactive kinin found in BAL fluid correlated with the presence of kininogenase activity (P = 0.002). The cleavage pattern of 125I-HMWK by the BAL fluid kininogenase (a dominant 65,000-mol wt fragment), and synthetic inhibitor profile (phe-phe-arg-CH2Cl and phenylmethylsulfonyl fluoride) were compatible with a tissue kallikrein. Peak kininogenase activity eluted at an apparent molecular weight of 20,000-34,000 by HPLC gel filtration. Its antigenic identity was established by immunoblotting with anti-human urinary kallikrein antibody and its activity was inhibited by this antibody. Lysylbradykinin was generated during incubation of fractionated BAL fluid and purified HMWK, the characteristic cleavage product of the tissue kallikreins. We conclude that elevated amounts of tissue kallikrein and kinin are present in the bronchoalveolar spaces of asthmatic subjects. Kinin generation may contribute to the asthmatic response directly through edema formation and smooth muscle contraction and by augmenting release and/or production of preformed (histamine) and secondary mediators such as leukotrienes and platelet-activating factor.

The quality of oral anticoagulant therapy and recurrent venous thrombotic events in the Leiden Thrombophilia Study.

BACKGROUND: The International Normalized Ratio (INR) target range is a relatively narrow range in which the efficacy of oral anticoagulant treatment, i.e. prevention of extension and recurrence of thrombosis, is balanced with the risk of hemorrhagic complications. Over the years, different INR target ranges have been implemented for individual indications, depending on their thrombotic potential. In most of the studies defining these INR targets, the treatment of the patients was aimed at a certain INR range, but in the analysis no account was taken of the time that the patients spent within this range in reality. METHODS: The Leiden Thrombophilia Study (LETS) is a population-based case-control study on risk factors for venous thrombosis, in which many genetic and acquired factors have been investigated. Our aim was to investigate the effect of the quality of the oral anticoagulant therapy for the initial venous thrombosis and its relationship with recurrence of thrombosis. Quality of anticoagulation was defined as the time spent at various INR levels during treatment, and we focused on the effect of sustained intensities above a certain INR in preventing recurrences later on. RESULTS: Two hundred and sixty-six patients with a total follow-up of 2495 patient-years were studied. The mean duration of the initial anticoagulant therapy was 194.5 days (range 48-4671). During follow-up, 58 recurrences were diagnosed (cumulative recurrence rate of 21.8% over 9 years). The mean INR during initial therapy was 2.90, with 90.3% [95% confidence interval (CI) 88.4-92.3%] of the time being spent above an INR of 2.0, and 39.1% (95% CI 35.5-42.7%) above an INR of 3.0. Patients who spent more time below the target range, or who had a shorter duration of anticoagulation, did not experience a higher risk of recurrence after the initial period of anticoagulation had passed. CONCLUSION: Provided that oral anticoagulant treatment is adequately managed, according to international guidelines, recurrent thrombosis cannot be ascribed to variation in the primary treatment. Further attempts to reduce the risk of recurrence should therefore be aimed at identifying other explanatory factors, and subsequently fine-tuning the target ranges.

Incidence and mortality of venous thrombosis: a population-based study.

BACKGROUND: Estimates of the incidence of venous thrombosis (VT) vary, and data on mortality are limited. OBJECTIVES: We estimated the incidence and mortality of a first VT event in a general population. METHODS: From the residents of Nord-Trøndelag county in Norway aged 20 years and older (n = 94 194), we identified all cases with an objectively verified diagnosis of VT that occurred between 1995 and 2001. Patients and diagnosis characteristics were retrieved from medical records. RESULTS: Seven hundred and forty patients were identified with a first diagnosis of VT during 516,405 person-years of follow-up. The incidence rate for all first VT events was 1.43 per 1000 person-years [95% confidence interval (CI): 1.33-1.54], that for deep-vein thrombosis (DVT) was 0.93 per 1000 person-years (95% CI: 0.85-1.02), and that for pulmonary embolism (PE) was 0.50 per 1000 person-years (95% CI: 0.44-0.56). The incidence rates increased exponentially with age, and were slightly higher in women than in men. The 30-day case-fatality rate was higher in patients with PE than in those with DVT [9.7% vs. 4.6%, risk ratio 2.1 (95% CI: 1.2-3.7)]; it was also higher in patients with cancer than in patients without cancer [19.1% vs. 3.6%, risk ratio 3.8 (95% CI 1.6-9.2)]. The risk of dying was highest in the first months subsequent to the VT, after which it gradually approached the mortality rate in the general population. CONCLUSIONS: This study provides estimates of incidence and mortality of a first VT event in the general population.

Double-stranded RNA increases kinin B1 receptor expression and function in human airway epithelial cells.

Increased levels of kinins have been detected within the airways during upper respiratory viral infections (URIs). Rhinovirus, the major URI associated with acute exacerbations of asthma, is an ssRNA virus that primarily infects the airway epithelium and produces dsRNA during replication. We asked whether dsRNA could increase the expression of kinin receptors in airway epithelial cells, thereby potentiating the inflammatory consequences of kinin generation. Human airway epithelial cell line BEAS-2B was stimulated with the dsRNA analog Poly I:C and kinin receptor expression detected by quantitative RT-PCR as well as radioligand binding. Poly I:C induced an increase in B1 and B2 receptor mRNA levels in BEAS-2B and primary human normal bronchial epithelial cells. At the cell surface, only B1 receptor expression was increased by Poly I:C. Furthermore, pretreatment of BEAS-2B cells with Poly I:C enhanced the induction of phospho-ERK following B1 receptor ligand stimulation. To investigate whether these finding had potential in vivo relevance, we assessed B1 receptor expression in nasal tissue obtained from 8 normal human subjects with URIs and 3 control subjects. Five of the URI subjects demonstrated increased B1 receptor mRNA compared to the 3 control subjects. We suggest that increased expression of B1 receptor in the human airway following a URI could increase the risk of an exacerbation of asthma by contributing to increased inflammation in the airway.

A prospective study of anticardiolipin antibodies as a risk factor for venous thrombosis in a general population (the HUNT study).

We prospectively examined whether there is an association between elevated anticardiolipin antibody levels and the risk for a future first venous thrombosis (VT) in a general population. We studied this in a large population-based nested case-cohort study of 508 VT cases and 1464 matched control subjects from a cohort of 66,140 participants in the Health Study of Nord-Trøndelag in Norway. Venous thrombosis was validated using standardized criteria for venous thrombosis and pulmonary embolism. Prethrombotic serum anticardiolipin antibodies were measured by an enzyme-linked immunoassay. There was no association between elevated anticardiolipin antibody levels and subsequent venous thrombosis, overall or after stratification by sex, different age groups or idiopathic vs. secondary thrombosis. The overall odds ratio was 1.11 (95% CI: 0.71-1.74) for greater than vs. less than the 95th percentile of anticardiolipin antibody levels. In conclusion, in this general population sample elevated anticardiolipin antibody levels was not a risk factor for subsequent venous thrombosis.

Mastocytosis: diverse presentations and outcomes.

Within the general category of mastocytosis lies an array of clinical presentations with differing prognostic implications. We report 3 cases of systemic mastocytosis distinguished by novel aspects of the disease. Case 1 documents the first successful orthotopic liver transplantation in a patient with mastocytosis; case 2 depicts a potential hereditary component of mastocytosis; and case 3 documents the progression of mastocytosis with hematologic abnormality to mast cell leukemia. Future investigations, such as the early definition of c-kit receptor mutations, may provide additional insight as to the molecular basis for this heterogeneous disease and guidance for prognostic implications and targeted therapies.

The effect of exercise and metformin treatment on circulating free DNA in pregnancy.

INTRODUCTION: Some pregnancy complications are characterized by increased levels of cell-free fetal (cffDNA) and maternal DNA (cfmDNA), the latter may also be elevated during physical strain. This study aims at assessing the impact of exercise and metformin intervention in pregnancy, and to compare the levels of cell free DNA in pregnant women with or without PCOS diagnosis. METHODS: Consecutive women from two previous randomized controlled trials in pregnancy were included. Women came from a trial with organized exercise vs. standard antenatal care in pregnancy and a trial of metformin vs. placebo in PCOS women. Levels of cffDNA, cfmDNA and cell-free total DNA (cftDNA) were measured by qPCR. RESULTS: Training in pregnancy did not affect the levels of cffDNA, cfmDNA or cftDNA. PCOS-women treated with metformin had lower levels of cfmDNA and cftDNA at week 32 (mean ± SD: 301 ± 162 versus 570 ± 337, p = 0.012, 345 ± 173 versus 635 ± 370, p = 0.019); otherwise the levels were comparable to PCOS-controls. Metformin-treated PCOS-women had higher cffDNA at inclusion, in the 1st trimester; later on in pregnancy the levels in the metformin and placebo groups were equal. A comparison of pregnant women in the exercise study (TRIP) to placebo-treated pregnant PCOS-women, showed the levels of cffDNA, cfmDNA or cftDNA during mid-pregnancy (weeks 18-36) to be equal. DISCUSSION: Training during pregnancy was not associated with altered levels of cffDNA cfmDNA or cftDNA, but metformin treatment may reduce cfmDNA and cftDNA in pregnant PCOS women.

The relationship between body mass index, activated protein C resistance and risk of venous thrombosis.

BACKGROUND: High body mass index (BMI) is associated with an increased risk of venous thrombosis (VT). Clotting factor VIII levels are increased in obese subjects, possibly because of a chronic inflammatory state, which increases activated protein C (APC) resistance. The APC resistance in FV Leiden carriers could be aggravated and further worsened by high FVIII levels in blood group non-O carriers. We hypothesized that an association exists between BMI and APC resistance, and that this is amplified by the presence of FV Leiden and/or blood group non-O. METHODS: We used the Leiden Thrombophilia Study (LETS) to determine whether an association exists between BMI and APC resistance, and whether the combination of high BMI and APC resistance increases the risk of VT. In a pooled analysis of LETS and a Norwegian case-cohort study (TROL), we verified whether FV Leiden modified the risk of the occurrence of VT with increasing BMI, and whether this risk was further increased by blood group non-O. RESULTS: APC resistance increased linearly with increasing BMI, partly because of a concurrent rise in FVIII. A BMI in the median or upper tertile was associated with a 1.9-fold (95% confidence interval [CI] 1.0-2.5) and 2.2-fold (95% CI 1.4-3.4) increased risk as compared with the lowest tertile. Both relative risks decreased slightly after FVIII and APC resistance adjustments. The effect of BMI on VT risk was enhanced two-fold to 10-fold in FV Leiden or blood group non-O carriers. CONCLUSIONS: The increased risk of VT in individuals with high BMI is partly mediated by FVIII-related APC resistance. This risk is more pronounced when other causes of increased APC resistance are also present.

Increased levels of free thyroxine and risk of venous thrombosis in a large population-based prospective study.

BACKGROUND: Recent studies have shown that high levels of free thyroxine (FT4), even without leading to hyperthyroidism, are associated with a procoagulant state. OBJECTIVES: The aim of our study was to determine whether high levels of thyroid hormones are associated with an increased risk of venous thrombosis. PATIENTS/METHODS: From a prospective nested case-cohort design within the second Nord-Trøndelag Health Study (HUNT2) cohort (1995-1997; 66,140 subjects), all patients with venous thrombosis during follow-up (n=515) and 1476 randomly selected age-stratified and sex-stratified controls were included. Relative and absolute risks for venous thrombosis were calculated for different cut-off levels of thyroid hormones on the basis of percentiles in the controls and different times between blood sampling and thombosis. RESULTS: In subjects with an FT4 level above the 98th percentile (17.3 pmol L(-1)), the odds ratio (OR) was 2.5 (95% confidence interval [CI] 1.3-5.0) as compared with subjects with levels below this percentile. For venous thrombosis within 1 year from blood sampling, this relative risk was more pronounced, with an OR of 4.8 (95% CI 1.7-14.0). Within 0.5 years, the association was even stronger, with an OR of 9.9 (95% CI 2.9-34.0, adjusted for age, sex, and body mass index). For thyroid-stimulating hormone, the relationship was inverse and less pronounced. The absolute risk within 6 months in the population for FT4 levels above the 98th percentile was 6.1 per 1000 person-years (95% CI 1.7-15.7). CONCLUSIONS: Levels of FT4 at the upper end of the normal range are a strong risk factor for venous thrombosis. The risk increased with higher levels of thyroxine and shorter time between blood sampling and thrombosis. Further studies on the effect of clinical hyperthyroidism are warranted.

Sex difference in risk of recurrent venous thrombosis and the risk profile for a second event.

BACKGROUND: The risk of recurrent venous thrombosis is higher in men than in women, and this is so far unexplained. We set out to determine the influence of age, time between first and second event, type of first event, oral contraception, pregnancy and surgery. METHODS: We performed a prospective follow-up study of 474 patients with a first objective diagnosis of deep vein thrombosis, aged 18-70 years (Leiden Thrombophilia Study cohort). RESULTS: During 3477 person-years of follow-up, 90 recurrences occurred. The overall incidence rates of recurrence (IRs) were 40.9 per 1000 person-years in men and 15.8 per 1000 person-years in women. Men with an unprovoked first event had the highest risk of recurrence, with almost one-third experiencing a second unprovoked event within 8 years (IR 41.2 per 1000 person-years). This risk was three-fold lower in women [IR 14.2 per 1000 person-years; hazard ratio 2.8 (95% confidence interval 1.4-5.7)]. Age at diagnosis had little effect on recurrence rate, and nor had time elapsed since the first event. In women, almost half of the recurrences were provoked and were mainly related to oral contraceptive use or pregnancy. CONCLUSIONS: The higher recurrence rate in men than in women is not the result of differences in the environmental or transient risk factors that we studied. The risk profile for a second thrombotic event is clearly different from that of a first.

Elevated endogenous thrombin potential is associated with an increased risk of a first deep venous thrombosis but not with the risk of recurrence.

Measurement of the thrombin generating potential could provide a method for quantifying the composite effect of multiple risk factors. This study assessed the risk of a first as well as a recurrent venous thrombotic event associated with an increased endogenous thrombin potential (ETP). Analyses were performed in 360 patients and 404 control subjects of the Leiden Thrombophilia Study. The ETP was measured directly using a fluorogenic assay (Thrombinoscope). Individuals with an increased ETP, i.e. above 90th percentile measured in control subjects (>2109.0 nM x min) had a 1.5-fold [95% confidence interval (CI): 0.9-2.3] increased risk of a first deep venous thrombosis. The risk was more pronounced after the analysis was restricted to idiopathic thromboses, i.e. 1.7-fold (95% CI: 1.0-2.8). Overall, the hazard ratio of a recurrent thrombotic event associated with a high ETP, adjusted for age, sex and oral anticoagulant use was 1.1 (95% CI: 0.5-2.2). Thus, a high ETP was not associated with an increased relative risk of recurrent venous thrombosis. At present, the clinical relevance of the thrombin generation assay in predicting recurrent venous thrombosis remains uncertain.

Asthma mortality rates among California youths.

Asthma mortality rates for California youths (ages 5-17 years) were examined over the period 1981-1995. Data were analyzed by Poisson regression from the California Departments of Vital Statistics, Finance, and the U.S. Census Bureau. Aggregate statewide mortality demonstrated a 2.01%, statistically insignificant, upward trend without geographic clustering. Stratified race/ ethnicity rates differed significantly, with African-American mortality twice that of the Caucasian population. In addition, an increased number of deaths occurred in households of African-Americans, Caucasians (including Hispanics), and Hispanics with incomes below statewide medians. This study on California youths differs from reports on larger populations with its minimal aggregate increase in asthma mortality, yet mirrors national trends of disproportionate impact on African-Americans and the economically disadvantaged.

Montelukast is only partially effective in inhibiting aspirin responses in aspirin-sensitive asthmatics.

BACKGROUND: Leukotrienes have been implicated as major mediators of ASA-induced respiratory reactions. In several prior studies, pretreatment of ASA-sensitive respiratory disease (ASRD) patients with leukotriene modifiers have sometimes allowed subjects to tolerate previously established provoking doses of oral ASA or inhalation ASA-lysine, without respiratory reactions. OBJECTIVE: The purpose of this study was to examine whether ASA-provoked respiratory reactions would be blocked or attenuated by pretreatment with a cystLT1 receptor antagonist, montelukast, particularly if ASA doses were increased above their threshold doses. METHODS: Baseline ASA oral challenges were performed. Eight to 12 days later, following pretreatment with montelukast 10 mg daily, threshold and then escalating doses of ASA were used during repeat oral ASA challenges. The differences in responses between baseline and montelukast protected ASA oral challenges were then compared. RESULTS: Nine of 10 patients, despite pretreatment with montelukast, experienced at least naso-ocular reactions during their second oral ASA challenges. In four of nine patients, asthmatic reactions also occurred. In comparing baseline and montelukast protected ASA challenges, there were no statistically significant differences in their responses. CONCLUSIONS: Pretreatment with montelukast allowed only one patient to proceed through all challenge doses of ASA without any reactions. The remaining nine patients enjoyed only partial protection from respiratory reactions. Montelukast pretreatment was generally not effective in altering upper airway reactions and only partly effective in altering lower airway reactions.

Inhibition of monocyte leukotriene B4 production after aspirin desensitization.

Aspirin-sensitive patients may be desensitized through a graded series of exposures to aspirin. We investigated the underlying mechanism of aspirin desensitization by measuring the release of leukotrienes B4 and C4 from calcium ionophore-stimulated peripheral blood monocytes. Compared with monocytes from normal volunteers (n = 5), monocytes from patients with aspirin-sensitive asthma (n = 10) released increased amounts of thromboxane B2 (1060 +/- 245 pg/ml vs 456 +/- 62 pg/ml), leukotriene B4 (861 +/- 139 pg/ml vs 341 +/- 44 pg/ml), and leukotriene C4 (147 +/- 31 pg/ml vs 56 +/- 6 pg/ml) at baseline. After aspirin desensitization, thromboxane B2 release was almost completely suppressed in both groups. Leukotriene B4 release was significantly decreased in the aspirin-sensitive group (484 +/- 85 pg/ml) but not in the normal subject group (466 +/- 55 pg/ml). The need for prednisone decreased significantly after patients were desensitized to aspirin (10.4 +/- 2.2 mg/day to 1.6 +/- 2.8 mg/day). These results demonstrate that desensitization to aspirin results in decreased monocyte leukotriene B4 release. On the basis of the bronchospastic and inflammatory potential of leukotrienes, the decrease in leukotriene release may contribute to the clinical improvement seen after aspirin desensitization.

Arachidonic acid metabolism in monocytes of aspirin-sensitive asthmatic patients before and after oral aspirin challenge.

Aspirin and nonsteroidal antiinflammatory drugs induce bronchospastic reactions in patients with aspirin-sensitive respiratory disease. Although the mechanism of this reaction is unknown, all drugs that induce the respiratory reaction also inhibit the cyclooxygenase enzyme. The ensuing changes in arachidonate metabolism are presumed to play a role in the pathogenesis of the reaction. We measured generation of leukotrienes and thromboxane by calcium ionophore stimulated blood monocytes. Before aspirin challenge, monocytes released significantly more thromboxane B2 in patients with aspirin sensitivity than in patients without aspirin sensitivity or in healthy control subjects (p < 0.02). During aspirin-induced bronchospasm, release of leukotriene B4 increased significantly (45.5%, p = 0.018), whereas release of thromboxane B2 decreased (-46.9%, p = 0.028). Two hours after ingestion of 60 mg aspirin, normal monocyte release of thromboxane B2 did not drop, whereas leukotriene B4 release increased. Monocytes formed only minimal amounts of leukotriene C4. We conclude that the profile of released eicosanoids from aspirin-sensitive monocytes is distinct from non-aspirin-sensitive subjects, and that these differences could contribute to the development of bronchospasm after aspirin ingestion.

Requirement of phosphatidylinositol 3-kinase activity for bradykinin stimulation of NF-kappaB activation in cultured human epithelial cells.

The signaling mechanisms utilized by bradykinin (BK) to activate the transcription factor nuclear factor kappaB (NF-kappaB) are poorly defined. We previously demonstrated that BK-stimulated NF-kappaB activation requires the small GTPase RhoA. We present evidence that BK-induced NF-kappaB activation both activates and requires phosphatidylinositol 3-kinase (PI 3-kinase) in A549 human epithelial cells. Pre-treatment with the PI 3-kinase-specific inhibitors, wortmannin, and LY294002 effectively blocked BK-induced PI 3-kinase activity. Wortmannin and LY294002 also abolished BK-induced NF-kappaB activation, as did transient transfection with a dominant negative mutant of the p85 subunit. BK-stimulated PI 3-kinase activity and NF-kappaB activation were sensitive to pertussis but not cholera toxin, suggesting that the B2 BK receptors transducing the response were coupled to Galphai or Galphao heterotrimeric G proteins. Tumor necrosis factor alpha (TNFalpha) also stimulated increased PI 3-kinase activity, however TNFalpha-stimulated NF-kappaB activation was not affected by the PI 3-kinase inhibitors or the p85 dominant negative mutant. These findings provide evidence that BK-induced NF-kappaB activation utilizes a signaling pathway that requires activity of both RhoA and PI 3-kinase and is distinct from the signaling pathway utilized by TNFalpha. Furthermore, we show that the p85 regulatory subunit is required for activation of PI 3-kinase activity by this G protein-coupled receptor.

Inhibition of human bronchial kallikrein in asthma.

Human bronchial kallikrein (HBK) is the major kinin-generating enzyme in the airways of asthmatic subjects. We examined the in vitro inhibition of HBK and its in vivo regulation in asthma. HBK kininogenase activity was measured by cleavage of radiolabeled purified high molecular weight kininogen (HMWK) (125I HMWK). Functional inhibition of the enzyme was present after co-incubation with either normal human plasma (NHP) or preparations of alpha-1-proteinase inhibitor (alpha 1-PI). Stable HBK inhibitor complex was detected at 92 K by immunoblotting employing anti-HUK as a probe. Anti alpha 1-PI probes did not demonstrate the 92 K complex under identical conditions, raising the possibility of an additional co-purifying protein involved in HBK binding. alpha 1-PI antigenic and activity levels were measured in asthmatic bronchoalveolar lavage (BAL) fluid. In only a single sample of the six examined was alpha 1-PI activity detected. In two of the remaining five samples, low levels of alpha 1-PI antigen were present which were functionally inactive. In the BAL fluid containing alpha 1-PI activity, progressive functional inhibition of kininogenase activity correlating with HBK inhibitor complex formation occurred during BAL fluid incubation. In contrast, BAL fluid lacking alpha 1-PI activity failed to show progressive kininogenase inhibition or complex formation under identical conditions. In all experiments, the time course of HBK inhibitor interaction was markedly prolonged, requiring 150-min co-incubation with either NHP or the alpha 1-PI preparation for greater than 80% inhibition of function and near maximal complex formation. The slow rate of inhibition of HBK may allow for its continued activity and kinin generation in the airways of asthmatic subjects.