Glycaemic impact of patient-led use of sensor-guided pump therapy in type 1 diabetes: a randomised controlled trial

AIMS/HYPOTHESIS

The objective of this study was to assess the impact of patient-led sensor-guided pump management on glycaemic control, and compare the effect with that of standard insulin pump therapy.

METHODS

An open multicentre parallel randomised controlled trial was conducted at five tertiary diabetes centres. Participants aged 13.0-40.0 years with well-controlled type 1 diabetes were randomised 1:1 to either study group for 3 months. Randomisation was carried out using a central computer-generated schedule. Participants in the intervention group used sensor-guided pump management; no instructive guidelines in interpreting real-time data were provided ('patient-led' use). Participants in the control group continued their original insulin pump regimen. Continuous glucose monitoring (CGM) and HbA(1c) level were used to assess outcomes. The primary outcome was the difference in the proportion of time in the target glycaemic range during the 3 month study period (derived from CGM, target range 4-10 mmol/l). Secondary outcomes were difference in HbA(1c), time in hypoglycaemic (< or =3.9 mmol/l) and hyperglycaemic (> or =10.1 mmol/l) ranges and glycaemic variability.

RESULTS

Sixty-two participants were recruited and randomised; 5/31 and 2/31 withdrew from intervention and control groups, respectively, leaving 26/31 and 29/31 for the intention-to-treat analyses. When adjusted for baseline values, the mean end-of-study HbA(1c) was 0.43% lower in the intervention group compared with the control group (95% CI 0.19 to 0.75%; p = 0.009). No difference was observed in CGM-derived time in target (measured difference 1.72; 95% CI -5.37 to 8.81), hypoglycaemic (0.54; 95% CI -3.48 to 4.55) or hyperglycaemic (-2.18; 95% CI -10.0 to 5.69) range or in glycaemic variability (-0.29; 95% CI -0.34 to 0.28). Within the intervention group, HbA(1c) was 0.51% lower in participants with sensor use > or =70% compared with participants with sensor use <70% (95% CI -0.98 to -0.04, p = 0.04). Five episodes of device malfunction occurred.

CONCLUSIONS/INTERPRETATION

Individuals established on insulin pump therapy can employ sensor-guided pump management to improve glycaemic control. An apparent dose-dependent effect of sensor usage was noted; however, frequent use of this technology (> or =70%) was not universally acceptable.

TRIAL REGISTRATION

ACTRN12606000049572

Inclusive K(S);(0)K(S);(0) resonance production in ep collisions at HERA

Inclusive K_{S};{0}K_{S};{0} production in ep collisions at the DESY ep collider HERA was studied with the ZEUS detector using an integrated luminosity of 0.5 fb;{-1}. Enhancements in the mass spectrum were observed and are attributed to the production of f_{2}(1270)/a_{2};{0}(1320), f_{2};{'}(1525) and f_{0}(1710). Masses and widths were obtained using a fit which takes into account theoretical predictions based on SU(3) symmetry arguments, and are consistent with the Particle Data Group values. The f_{0}(1710) state, which has a mass consistent with a glueball candidate, was observed with a statistical significance of 5 standard deviations. However, if this state is the same as that seen in gammagamma-->K_{S};{0}K_{S};{0}, it is unlikely to be a pure glueball state.

A 10-s sprint performed prior to moderate-intensity exercise prevents early post-exercise fall in glycaemia in individuals with type 1 diabetes

AIMS/HYPOTHESIS

We investigated whether a 10-s maximal sprint effort performed immediately prior to moderate-intensity exercise provides another means to counter the rapid fall in glycaemia associated with moderate-intensity exercise in individuals with type 1 diabetes.

MATERIALS AND METHODS

Seven complication-free type 1 diabetic males (21.6 +/- 3.6 years; mean+/-SD) with HbA(1c) levels of 7.4 +/- 0.7% injected their normal morning insulin dose and ate their usual breakfast. When post-meal glycaemia fell to approximately 11 mmol/l, participants were asked to perform a 10-s all-out sprint (sprint trial) or to rest (control trial) immediately before cycling at 40% of peak rate of oxygen consumption for 20 min, with both trials conducted in a random counterbalanced order.

RESULTS

Sprinting did not affect the rapid fall in glycaemia during the subsequent bout of moderate-intensity exercise (2.9 +/- 0.4 mmol/l in 20 min; p = 0.00; mean+/-SE). However, during the following 45 min of recovery, glycaemia in the control trial decreased by 1.23 +/- 0.60 mmol/l (p = 0.04) while remaining stable in the sprint trial, subsequently decreasing in this latter trial at a rate similar to that in the control trial. The large increase in noradrenaline (norepinephrine) (p = 0.005) and lactate levels (p = 0.0005) may have contributed to the early post-exercise stabilisation of glycaemia in the sprint trial. During recovery, adrenaline (epinephrine) and NEFA levels increased marginally in the sprint trial, but other counter-regulatory hormones did not change significantly (p < 0.05).

CONCLUSIONS/INTERPRETATION

A 10-s sprint performed immediately prior to moderate-intensity exercise prevents glycaemia from falling during early recovery from moderate-intensity exercise in individuals with type 1 diabetes.

Perinatal risk factors for childhood Type 1 diabetes in Western Australia--a population-based study (1980-2002)

AIMS

To investigate perinatal risk factors for childhood Type 1 diabetes in Western Australia, using a complete population-based cohort.

METHODS

Children born between 1980 and 2002 and diagnosed with Type 1 diabetes aged < 15 years (n = 940) up to 31 December 2003 were identified using a prospective population-based diabetes register with a case ascertainment rate of 99.8%. Perinatal data were obtained for all live births in Western Australia from 1980 to 2002 (n = 558 633) and record linkage performed to identify the records of cases.

RESULTS

The incidence of Type 1 diabetes increased by 13% for each 5-year increase in maternal age [adjusted incidence rate ratio (IRR) 1.13, 95% confidence interval (CI) 1.05, 1.21], by 13% for every 500-g increase in birth weight (adjusted IRR 1.13, 95% CI 1.04, 1.23). The incidence decreased with increasing birth order (adjusted IRR 0.89, 95% CI 0.82, 0.96) and increasing gestational age (adjusted IRR 0.84, 95% CI 0.77, 0.93). A higher incidence of Type 1 diabetes was associated with an urban vs. non-urban maternal address at the time of birth (adjusted IRR 1.38, 95% CI 1.18, 1.63), but no association was found with socio-economic status of the area.

CONCLUSIONS

A higher incidence of Type 1 diabetes was associated with increasing maternal age, higher birth weight, lower gestational age, lower birth order and urban place of residence at the time of birth.

The relationship between ACE genotype and risk of severe hypoglycaemia in a large population-based cohort of children and adolescents with type 1 diabetes

AIMS/HYPOTHESIS

Genetic factors may account for familial clustering related to diabetes complications. Studies have shown a significant relationship between the presence of the deletion (D) allele of the gene encoding ACE and risk of severe hypoglycaemia. This large prospective cohort study assesses this relationship in a large sample of children and adolescents with type 1 diabetes.

SUBJECTS AND METHODS

We studied 585 children and adolescents (mean age 11.9 +/- 4 years, 48.4% males). The frequency of severe hypoglycaemia (an event leading to loss of consciousness or seizure) was prospectively assessed over the 13-year period 1992-2004. Patients were seen with their parents every 3 months and data recorded at each visit. The ACE gene was detected using PCR.

RESULTS

In our cohort of 585 children, 186 (31.8%) had at least one episode of severe hypoglycaemia, and of these 28.0% had the II genotype, 48.9% had the ID genotype and 23.1% had the DD genotype. This was in agreement with the Hardy-Weinberg proportion. A total of 477 severe hypoglycaemic episodes was recorded with a total of 3,404 person-years of follow-up, giving a total incidence of 14 per 100 patient-years. No significant increase in risk for DD genotype (incidence rate ratio = 0.97, 95% CI 0.61-1.55) relative to II genotype was observed.

CONCLUSIONS/INTERPRETATION

This large prospective study concludes that the presence of the D allele of the ACE gene does not predict a significantly higher risk of severe hypoglycaemia in type 1 diabetic children and adolescents.

Effect of intermittent high-intensity compared with continuous moderate exercise on glucose production and utilization in individuals with type 1 diabetes

Previously, the decline in glycemia in individuals with type 1 diabetes has been shown to be less with intermittent high-intensity exercise (IHE) compared with continuous moderate-intensity exercise (MOD) despite the performance of a greater amount of total work. The purpose of the present study was to determine whether this lesser decline in glycemia can be attributed to a greater increment in endogenous glucose production (Ra) or attenuated glucose utilization (Rd). Nine individuals with type 1 diabetes were tested on two separate occasions, during which either a 30-min MOD or IHE protocol was performed under conditions of a euglycemic clamp in combination with the infusion of [6,6-(2)H]glucose. MOD consisted of continuous cycling at 40% VO2 peak, whereas IHE involved a combination of continuous exercise at 40% VO2 peak interspersed with additional 4-s maximal sprint efforts performed every 2 min to simulate the activity patterns of intermittent sports. During IHE, glucose Ra increased earlier and to a greater extent compared with MOD. Similarly, glucose Rd increased sooner during IHE, but the increase by the end of exercise was comparable with that elicited by MOD. During early recovery from IHE, Rd rapidly declined, whereas it remained elevated after MOD, a finding consistent with a lower glucose infusion rate during early recovery from IHE compared with MOD (P<0.05). The results suggest that the lesser decline in glycemia with IHE may be attributed to a greater increment in Ra during exercise and attenuated Rd during exercise and early recovery.

Can we identify adolescents at high risk for nephropathy before the development of microalbuminuria?

AIMS

To determine whether higher than average albumin excretion during early puberty identifies subjects who will subsequently develop microalbuminuria (MA) and clinical proteinuria.

METHODS

Longitudinal data from the Oxford Regional Prospective Study of Childhood Diabetes (ORPS; n = 554, median duration of follow-up 10 years; range 3.0-16.7) with assessment of albumin/creatinine ratios in three early morning urine samples collected annually. An albumin excretion phenotype was derived from longitudinal data, for each individual, defining deviation from the mean of regression models, including covariates gender, age, duration of diabetes and age at assessment. Tracking of the phenotypes was confirmed in a second independent cohort from Perth, Australia.

RESULTS

The albumin excretion phenotype showed reasonable correlation between age 11-15 years and age 16-18 years in both cohorts, indicative of good 'tracking'. In the ORPS cohort, tertiles of the albumin excretion phenotype at aged 11-15 years were predictive of subsequent risk for the development of MA. All of the subjects developing clinical proteinuria had an albumin excretion phenotype in the upper tertile or an HbA(1c) > 9% at aged 11-15 years.

CONCLUSIONS

Identification of adolescents at risk of diabetic nephropathy using an albumin excretion phenotype is feasible. When combined with elevated HbA(1c), it may identify subjects for trial of early intervention with angiotensin-converting enzyme inhibitors/angiotensin-II receptor antagonists and statins to improve long-term prognosis in these subjects where sustained improvement in glycaemic control may be difficult to achieve.

Early changes in 24-hour ambulatory blood pressure are associated with high normal albumin excretion rate in children with type 1 diabetes mellitus

OBJECTIVE

The relationship between urinary albumin excretion rate (AER) and elevated blood pressure (BP) is unclear as a cause-effect phenomenon in the development of diabetic nephropathy. The aim of this study was to examine the association between AER, HbA1c and BP in children with normoalbuminuria.

METHODS

24-hour ambulatory BP assessment was performed in 78 children with type 1 diabetes mellitus (DM1), age mean +/- SD 13.4 +/- 2.7 yr, range 7.3-18.3 yr, DM1 duration mean +/- SD 6.6 +/- 2.9 yr, range 2.1-11.9 yr. Using generalised linear mixed models with systolic (SBP) and diastolic (DBP) blood pressure as dependent variables, the effects of AER and HbA1c were examined, adjusting for age, gender, DM1 duration and insulin dose.

RESULTS

Patients with high normal AER (7-20 microg/min) had higher SBP during daytime and night-time compared to the low normal AER (< or = 7 microg/min) (mean +/- SD 118.20 +/- 7.98 and 110.33 +/- 7.08 mm Hg, p = 0.02; mean +/- SD 108.76 +/- 9.21 and 100.20 +/- 7.75 mm Hg, p = 0.03, respectively). DBP was also higher both during day- and night-time when compared to the < or = 7 microg/min group (mean +/- SD 73.40 +/- 6.50 and 64.86 +/- 5.67 mm Hg, p = 0.002; mean +/- SD 62.50 +/- 6.75 and 56.30 +/- 5.56 mm Hg, p = 0.03 day- and night-time, respectively).

CONCLUSION

A rise in SBP and DBP is associated with increased levels of AER even within the normal range.

Insulin pump therapy in children and adolescents: improvements in key parameters of diabetes management including quality of life

AIMS

To determine the impact of insulin pump therapy (continuous subcutaneous insulin infusion) on key parameters of diabetes management including quality of life in children and adolescents with Type 1 diabetes mellitus (T1DM).

METHODS

All patients started on insulin pump therapy were prospectively followed before and after institution of insulin pump therapy. Data collected included age, duration of diabetes, glycated haemoglobin levels (HbA1c), anthropometric data and episodes of severe hypoglycaemia defined as hypoglycaemia resulting in coma or convulsion. A subset of patients also completed the Diabetes Quality of Life Instrument (DQOL) and Self-Efficacy for Diabetes Scale (SED) questionnaires to assess quality of life.

RESULTS

At the time of analysis, 100 patients had been managed with insulin pump therapy. The mean age when starting pump therapy was 12.5 (3.9-19.6) years. Duration of therapy ranged from 0.2 to 4.0 years (mean 1.4 years, median 1.5 years). HbA1c decreased from 8.3 +/- 0.1% prior to pump therapy to 7.8 +/- 0.1% (P < 0.0001). Episodes of severe hypoglycaemia decreased from 32.9 to 11.4 per 100 patient years. Components of quality of life measures showed improvement on pump treatment. BMI standard deviation scores (z scores) did not increase.

CONCLUSIONS

Pump therapy is proving an effective means of insulin therapy in the young patient that shows promise to improve glycaemic control with a reduction in hypoglycaemia frequency. Quality of Life measures suggest that psychosocial outcomes may be improved.

Evaluation of isometamidium levels in the serum of sheep and goats after prophylactic treatment against trypanosomosis

Isometamidium chloride has been used for the control of trypanosomosis in animals for over 36 years, but recently there have been reports of prophylaxis failure under natural conditions. In this study, use of the drug for prophylactic purpose against trypanosomosis in small ruminants was investigated. Forty-two sheep and 44 goats were divided into four treatment groups. Groups 1 and 2 were treated with isometamidium chloride (Samorin, Rhone Merieux, Lyon, France) at 3-month intervals while groups 3 and 4 were used as controls. All the animals were exposed to natural tsetse challenge and monitored for serum isometamidium levels and anti-trypanosome antibodies. Seven days after drug administration, isometamidium levels were significantly higher in goats 13.7+/-0.07 ng/ml than in sheep 6.2+/-0.06 ng/ml. However, the elimination half-life in the sheep was 14.2+/-0.92 days and was significantly higher (P> 0.05) than that of the goats 12+/-0.5 days. This study established that isometamidium metabolism differs between sheep and goats and this difference may have important implications in high tsetse challenge areas.

Evaluating risk factors associated with severe hypoglycaemia in epidemiology studies-what method should we use?

AIMS

To determine the most appropriate regression models to use when assessing risk factors for severe hypoglycaemia and to investigate the impact of model misspecification and its clinical implications.

METHODS

A total of 1229 children with Type 1 diabetes (mean age 11.7 years sd 4.1), of which 605 (49.2%) were males, were studied. Prospective assessment of severe hypoglycaemia (an event leading to loss of consciousness or seizure) was made over the 9-year period, 1992-2001. Patients were seen every 3 months and episodes of hypoglycaemia along with clinical data were recorded. Over 70% of children never experienced a severe hypoglycaemic event. Data were analysed using the Poisson regression, negative binomial, zero-inflated Poisson (ZIP) and zero-inflated negative binomial (ZINB) models. The over-dispersion and likelihood ratio statistics were calculated and the analytical methods compared.

RESULTS

The Poisson regression model did not fit the data well. The negative binomial and the zero inflated Poisson and negative binomial models fitted the data better than Poisson.

CONCLUSIONS

The commonly used Poisson regression models to analyse hypoglycaemia epidemiology may lead to biased parameter estimates and incorrect determination of risk factors for hypoglycaemia. We recommend the use of the negative binomial or zero inflated models to examine any risk factors associated with severe hypoglycaemia. Careful consideration must be given to the interpretation of hypoglycaemia surveys and their analysis.

Continued increase in the incidence of childhood Type 1 diabetes in a population-based Australian sample (1985-2002)

AIMS/HYPOTHESIS

Our aim was to determine the incidence of Type 1 diabetes in children who were 0 to 14 years of age in Western Australia from 1985 to 2002, and to analyse the trends in incidence rate over the same period.

METHODS

Primary case ascertainment was from a prospective population-based diabetes register that was established in 1987, and secondary case ascertainment was from the Western Australia Hospital Morbidity Data System. Denominator data were obtained from the Australian Bureau of Statistics. Poisson regression was used to analyse the incidence rates by calendar year, sex and age at diagnosis.

RESULTS

There was a total of 1144 cases (560 boys, 584 girls). Using the capture-recapture method, case ascertainment was estimated to be 99.8% complete. The mean age standardised incidence from 1985 to 2002 was 16.5 per 100,000 person years (95% CI 14.7-18.2), ranging from 11.3 per 100,000 in 1985 to 23.2 per 100,000 in 2002. The incidence increased on average by 3.1% (95% CI 1.9%-4.2%) a year over the period ( p<0.001). No significant difference was found between boys and girls. A significant increase in incidence was found in all age groups, with no disproportionate increase found in the 0 to 4-year-olds.

CONCLUSIONS/INTERPRETATION

The incidence of childhood-onset Type 1 diabetes in Western Australia has increased significantly over the past 18 years and shows no signs of abating. In contrast to other studies, a higher rate of increase was not found in the youngest children.

Subcutaneous glucose sensor values closely parallel blood glucose during insulin-induced hypoglycaemia

AIMS

To assess the accuracy of the Minimed continuous glucose monitoring system (CGMS) in estimating blood glucose concentration during a controlled reduction in blood glucose.

RESEARCH DESIGN AND METHODS

We studied nine adolescent diabetics (age 14 +/- 1.5 years) wearing the CGMS during hyperinsulinaemic hypoglycaemic clamp studies. The glucose values obtained by the CGMS were compared with the venous blood samples taken during the studies and measured at the bedside using a glucose oxidase technique.

RESULTS

Blood glucose was lowered from euglycaemia to a mean of 2.8 mmol/l over 120 min and maintained at that level for a further 40 min. A total of 429 paired glucose measurements were available for analysis. Analysis using weighted Deming regression and t-tests revealed small differences between the methods, with blood glucose levels slightly higher than interstitial fluid levels. The mean difference across all values was 0.13 mmol/l. The observed difference was greatest at blood glucose values < 3.3 mmol/l.

CONCLUSIONS

This study suggests that during a fall in systemic glucose the subcutaneous glucose sensor provides an accurate reflection of blood glucose. However, a small difference is apparent at blood glucose values < 3.3 mmol/l.

Larger numbers of CD4(bright) dendritic cells in donor bone marrow are associated with increased relapse after allogeneic bone marrow transplantation

Relapse is the major cause of death after allogeneic bone marrow transplantation (BMT). This study tested the hypothesis that the numbers of donor mononuclear cells, lymphocytes, and CD34(+) cells influence relapse and event-free survival (EFS) after BMT. The study population consisted of 113 consecutive patients with hematologic malignancies who underwent non-T-cell-depleted BMT from HLA-matched siblings. Sixty-four patients had low-risk diagnoses (ALL/AML CR1, MDS RA/RARS, and CML CP1); 49 patients had high-risk diagnoses (all others). CD34(+) cells, T cells, B cells, natural killer cells, monocytes, and a rare population of CD3(-), CD4(bright) cells in the allografts were measured by flow cytometry. The CD3(-), CD4(bright) cells in bone marrow had the same frequency and phenotype as CD123(bright) type 2 dendritic cell (DC) progenitors, and they differentiated into typical DCs after short-term culture. Cox regression analyses evaluated risk strata, age, gender, and the numbers of nucleated cells, CD3(+) T cells, CD34(+) hematopoietic cells, and CD4(bright) cells as covariates for EFS, relapse, and nonrelapse mortality. Recipients of larger numbers of CD4(bright) cells had significantly lower EFS, a lower incidence of chronic graft-versus-host disease (cGVHD), and an increased incidence of relapse. Recipients of larger numbers of CD34(+) cells had improved EFS; recipients of fewer CD34(+) cells had delayed hematopoietic engraftment and increased death from infections. In conclusion, the content of donor CD4(bright) cells was associated with decreased cGVHD and graft-versus-leukemia effects in recipients of allogeneic bone marrow transplantation, consistent with a role for donor DCs in determining immune responses after allogeneic BMT.

Trypanosoma vivax--out of Africa

Trypanosoma vivax is a blood parasite of ruminants that was introduced into Latin America in cattle imported from Africa, possibly in the late 19th century. The parasite has now spread to ten of the 13 countries of the South American continent, often resulting in a severe wasting disease and death. Here, we review the current state of knowledge about this parasite and the problems faced by animal health agencies in controlling the disease.

The expression of inherited hydrocephalus in H-Tx rats

OBJECTIVES

H-Tx rats develop severe hydrocephalus in late gestation. The breeding colony maintained at the University of Florida stems from one pair obtained in 1992. The aims of this study were to characterize the expression of hydrocephalus in the H-Tx rat colony, to perform within-strain and between-strain DNA analysis and to examine hydrocephalus expression in specific breeding experiments.

METHODS AND OBSERVATIONS

Matings between normal rats produce hydrocephalic offspring almost without exception, and the overall frequency is stable between generations at 40%. However, frequency varies with parity, being only 27% in the first litters, and it also varies with sex, there being an excess of male hydrocephalics. Mating between shunt-treated hydrocephalic rats did not increase the frequency. DNA typing with microsatellite markers showed that there was some residual heterogeneity in the colony despite inbreeding for 22 generations, although it did not segregate with hydrocephalus. Test mating with two other inbred strains, F344 and LEW produced some affected pups in the LEW cross only. A backcross experiment between H-Tx and F344 produced 12.3% severely-affected pups and 5.4% pups with a mild form, indicating the presence of several susceptibility genes.

CONCLUSIONS

All animals in our H-Tx colony are homozygous for the hydrocephalus loci, but there is incomplete penetrance.

High dose chemotherapy without hematopoietic cell support for the treatment of refractory lymphoma

Conventional dose combination chemotherapy for patients with relapsed or refractory lymphoma is rarely curative. High dose chemotherapy followed by hematopoietic progenitor cell transplant (HPCT) has a clearly defined role in patients who have first relapsed after standard CHOP chemotherapy for lymphoma. However, the role of HPCT is less well defined for patients with chemo-resistant, or chemo-refractory disease. Sixteen patients (15 Non-Hodgkin's, 1 Hodgkin's Disease) were entered into a phase II study to determine if a dose intensive induction regimen in heavily pre-treated refractory lymphoma patients could permit further consolidation with HPCT. The primary endpoints were survival, response, toxicity, and resource utilization. The regimen consisted of continuous infusion etoposide 1 or 2 gm/m2/72 hours, idarubicin 12 mg/m2/d for 3 days followed by cytarabine 2 gm/m2/72 hours on days 8, 9, and 10 (VIC). Fifteen patients were evaluable for objective response. The overall response rate was 53% with 7 patients achieving a partial response and 1 patient achieving a complete response. Of the 8 responders, 6 patients subsequently received high dose chemotherapy followed by HPCT (4 autologous, 2 allogeneic). The median survival was 176 days for the non-responders contrasted with 722 days for the responders. The average duration of hospitalization was 38 days. Toxicity was mainfest primarily as mucositis with a median grade of 3 among the first 13 patients, and a median grade of 2 in three subsequent patients who received an etoposide dose of 1 gm/m2/72 hours. All patients had an episode of neutropenic fever and 5 patients developed clinically significant pneumonitis during therapy. The VIC regimen is active in the treatment of chemo-refractory lymphoma with clinically significant differences in survival for patients who respond to therapy. Further modifications to the regimen could include the addition of a topoisomerase I inhibitor for synergy with etoposide, and using VIC as part of a tandem transplant regimen where response to VIC would allow further therapy with a myeloablative induction followed by HPCT.

Enhanced Cloud Disruption by Magnetic Field Interaction

We present results from the first three-dimensional numerical simulations of moderately supersonic cloud motion through a tenuous, magnetized medium. We show that the interaction of the cloud with a magnetic field perpendicular to its motion has a great dynamical impact on the development of instabilities at the cloud surface. Even for initially spherical clouds, magnetic field lines become trapped in surface deformations and undergo stretching. The consequent field amplification that occurs there and, in particular, its variation across the cloud face then dramatically enhance the growth rate of Rayleigh-Taylor unstable modes, hastening the cloud disruption.

A simple procedure for the extraction of trypanosome DNA and host protein from dried blood meal residues of haematophagous diptera

A two step elution method is described for the extraction of host serum proteins and trypanosome DNA from a single dried insect gut smear preparation. The first low temperature elution yields material suitable for use in ELISA to determine the host species on which the fly last fed while the results of the second, high temperature, elution can be used in a PCR assay to detect the presence of trypansosomal DNA. The method can be used to extract material from both fly squashes and blood spots dried onto filter paper and could simplify the collection and processing of samples for epidemiological studies on trypanosomoses and other vector borne pathogens.

Changes in free insulin-like growth factor-1 and leptin concentrations during acute metabolic decompensation in insulin withdrawn patients with type 1 diabetes

To determine the effect of acute insulin withdrawal and its subsequent replacement on components of the insulin-like growth factor (IGF)-1 binding protein system and on circulating leptin levels in patients with type 1 diabetes. Seventeen patients (age 31 yr +/-10) with type 1 diabetes treated with continuous subcutaneous insulin infusion (HbA1c 7.6% +/-1.0) were studied. The protocol consisted of two phases: acute insulin withdrawal of up to 8 h followed by a further 2-h period of insulin replacement. For the first phase the basal insulin infusion was stopped (at 0300 h), and for the second a single dose of either regular human or insulin lispro was given subcutaneously (0.2 U/kg). Plasma insulin, glucose, growth hormone, glucagon, IGF-1, free IGF-1, IGFBP-1, -2, -3 and leptin were measured.

RESULTS

After interruption of the basal insulin infusion, plasma free insulin levels fell from 60+/-12.0 pmol/L to 10.8+/-4.2 pmol/L, and plasma glucose rose from 5.6+/-0.4 mmol/L to 14.8+/-1.2 mmol/L (P< 0.01). During insulin withdrawal, IGFBP-1 increased by more than 6-fold (from 32+/-8 to 205+/-17 ng/mL, P<0.001), IGFBP-3 increased significantly (from 2631+/-118 to 3053+/-101 ng/mL, P<0.001), and total IGF-1 levels declined modestly (from 226+/-33 to 182+/-26 ng/mL, P<0.001). In contrast, free IGF-1 concentrations (0.72+/-0.22 ng/mL at baseline) were markedly suppressed during insulin withdrawal to values below the detection limit of the assay (0.08 ng/mL) in 15 of the 17 patients (P<0.001). Circulating plasma leptin declined markedly in females from 20+/-3 ng/mL to 11+/-2 ng/mL (P<0.0001) and in males from 10+/-2 ng/mL to 7+/-2 ng/mL (P<0.02). Within 2 h of insulin replacement, the changes in circulating concentrations of IGFBP-1 and IGFBP-3 were partially reversed, and free IGF-1 levels rebounded to 0.54+/-0.22 ng/mL (P<0.1 vs. insulin withdrawal). Growth hormone, glucagon, and IGFBP-2 levels did not change significantly throughout the study. Despite the rapid restoration of plasma insulin and substrate levels, circulating leptin levels continued to fall in the 2-h period after insulin replacement in both females and males. The marked reduction in circulating free IGF-1 after insulin withdrawal and its increase after insulin administration suggest that acute changes in IGFBP concentrations induced by insulin are important regulators of IGF-1 bioavailability in patients with type 1 diabetes. In both males and females, the rapid induction of severe insulin deficiency is associated with a consistent fall in plasma leptin levels.

Genomic profiling of drug sensitivities via induced haploinsufficiency

Lowering the dosage of a single gene from two copies to one copy in diploid yeast results in a heterozygote that is sensitized to any drug that acts on the product of this gene. This haploinsufficient phenotype thereby identifies the gene product of the heterozygous locus as the likely drug target. We exploited this finding in a genomic approach to drug-target identification. Genome sequence information was used to generate molecularly tagged heterozygous yeast strains that were pooled, grown competitively in drug and analysed for drug sensitivity using high-density oligonucleotide arrays. Individual heterozygous strain analysis verified six known drug targets. Parallel analysis identified the known target and two hypersensitive loci in a mixed culture of 233 strains in the presence of the drug tunicamycin. Our discovery that both drug target and hypersensitive loci exhibit drug-induced haploinsufficiency may have important consequences in pharmacogenomics and variable drug toxicity observed in human populations.

Immunochemical analysis of quinol-thioether-derived covalent protein adducts in rodent species sensitive and resistant to quinol-thioether-mediated nephrotoxicity

2,3,5-Tris(glutathion-S-yl)hydroquinone (TGHQ) is nephrotoxic in male Fischer 344 rats (20 micromol/kg) and albino guinea pigs (200 micromol/kg), but not BALB/c or B6C3F1 mice or Golden Syrian hamsters (200 micromol/kg). Since quinones are known to alkylate proteins, and because such macromolecular damage may play a role in cytotoxicity, we investigated the covalent binding of TGHQ to kidney (target tissue) and liver (nontarget tissue) of rodents "sensitive" or "resistant" to the nephrotoxic effects of TGHQ. Immunohistochemical staining of tissue obtained 2 h after administration of TGHQ, with rabbit anti-2-bromo-N-(acetyl-L-cystein-S-yl)HQ antibodies, correlated with the subsequent region of necrosis observed 19 h after dosing in Fischer 344 rats and guinea pigs. Immunohistochemical staining was localized to the S3 segment of the renal proximal tubules, at the corticomedullary junction along the medullary rays, and in the outer stripe of the outer medulla. Immunostaining was also observed in the same region in hamsters, but subsequent necrosis did not develop. In contrast, no immunostaining was observed in mice. Moreover, immunostaining was not detected in the livers of any species. Western blot analysis revealed numerous immunoreactive renal proteins in TGHQ-treated animals. The most distinctive immunostaining renal proteins were observed in Fischer 344 rats at approximately 34 kDa (mitochondria), approximately 35 kDa (nuclei) which comigrated with histone H1, and approximately 73 kDa (urine) which comigrated with gamma-glutamyl transpeptidase. These adducted proteins were not detected in other species. Qualitative differences in alkylated proteins may therefore contribute to species susceptibility to TGHQ.

Decreased epinephrine responses to hypoglycemia during sleep

BACKGROUND

In patients with type I diabetes mellitus, hypoglycemia occurs commonly during sleep and is frequently asymptomatic. This raises the question of whether sleep is associated with reduced counterregulatory-hormone responses to hypoglycemia.

METHODS

We studied the counterregulatory-hormone responses to insulin-induced hypoglycemia in eight adolescent patients with type I diabetes and six age-matched normal subjects when they were awake during the day, asleep at night, and awake at night. In each study, the plasma glucose concentration was stabilized for 60 minutes at approximately 100 mg per deciliter (5.6 mmol per liter) and then reduced to 50 mg per deciliter (2.8 mmol per liter) and maintained at that concentration for 40 minutes. Plasma free insulin, epinephrine, norepinephrine, cortisol, and growth hormone were measured frequently during each study. Sleep was monitored by polysomnography.

RESULTS

The plasma glucose and free insulin concentrations were similar in both groups during all studies. During the studies when the subjects were asleep, no one was awakened during the hypoglycemic phase, but during the final 30 minutes of the studies when the subjects were awake both the patients with diabetes and the normal subjects had symptoms of hypoglycemia. In the patients with diabetes, plasma epinephrine responses to hypoglycemia were blunted when they were asleep (mean [+/-SE] peak plasma epinephrine concentration, 70+/-14 pg per milliliter [382+/-76 pmol per liter]; P=0.3 for the comparison with base line), as compared with when they were awake during the day or night (238+/-39 pg per milliliter [1299+/-213 pmol per liter] P=0.004 for the comparison with base line, and 296+/-60 pg per milliliter [1616+/-327 pmol per liter], P=0.004, respectively). The patients' plasma norepinephrine responses were also reduced during sleep, whereas their plasma cortisol concentrations did not increase and their plasma growth hormone concentrations increased slightly. The patterns of counterregulatory-hormone responses in the normal subjects were similar.

CONCLUSIONS

Sleep impairs counterregulatory-hormone responses to hypoglycemia in patients with diabetes and normal subjects.

Comparison of human regular and lispro insulins after interruption of continuous subcutaneous insulin infusion and in the treatment of acutely decompensated IDDM

OBJECTIVE

To compare the rapidity of metabolic decompensation after interruption of CSII between human regular and lispro insulin and to compare these two insulins in the correction of the hyperglycemia and ketosis of mildly decompensated IDDM. Lispro insulin may be especially useful for insulin pump therapy (continuous subcutaneous insulin infusion [CSII]).

RESEARCH DESIGN AND METHODS

A total of 18 patients with well-controlled IDDM (HbA1c 7.7 +/- 1.1%, age 30 +/- 11 years) were studied. All were being treated with CSII (nine with human regular and nine with lispro insulin). The study consisted of two phases: 1) an insulin interruption phase, in which the basal insulin infusion was stopped (at 0300) and plasma insulin, glucose, and beta-O-hydroxybutyrate (beta-OHB) were measured every 15-60 min for 6 h after interruption of the insulin infusion and 2) an insulin replacement phase, which involved measuring plasma insulin, glucose, and beta-OHB for 2 h after a single injection of either human regular or lispro insulin to correct the hyperglycemia and ketosis that developed during the first phase of the study.

RESULTS

After interruption of the basal insulin infusion during the insulin interruption phase, plasma insulin levels fell gradually in both groups to nadir values of 1.6 +/- 0.8 and 2.0 +/- 1.2 microU/ml in the regular insulin- and insulin lispro-treated groups, respectively. Plasma glucose concentrations rose to 13.8 +/- 1.9 and 16.0 +/- 1.7 mmol/l in the regular insulin- and insulin lispro-treated groups, respectively. No significant differences were seen between the therapy groups at any time in the insulin levels or in the concentrations of plasma glucose or beta-OHB. In the insulin replacement phase, insulin levels rose more rapidly in those treated with lispro insulin, reaching a greater peak value (e.g., at 60 min, plasma insulin 25 +/- 3.4 vs. 15.6 +/- 2.6 microU/ml, P < 0.05). In association with this, plasma glucose decreased to a lower nadir after lispro insulin (9.7 +/- 0.4 vs. 13.7 +/- 0.7 mmol/l, lispro- vs. regular-treated groups at 120 min after insulin administration, P < 0.01). beta-OHB levels decreased rapidly in both groups.

CONCLUSIONS

In patients treated with CSII, interruption of the basal insulin infusion in the middle of the night does not result in more rapid metabolic decompensation in patients treated with lispro compared with those treated with regular human insulin. Lispro insulin is effective in treating mild ketosis and hyperglycemia, and its rapid action may be advantageous in the "sick day" management at home of patients with IDDM.