Observations of Multiple Nuclear Reaction Histories and Fuel-Ion Species Dynamics in Shock-Driven Inertial Confinement Fusion Implosions

Fuel-ion species dynamics in hydrodynamiclike shock-driven DT^{3}He-filled inertial confinement fusion implosion is quantitatively assessed for the first time using simultaneously measured D^{3}He and DT reaction histories. These reaction histories are measured with the particle x-ray temporal diagnostic, which captures the relative timing between different nuclear burns with unprecedented precision (∼10  ps). The observed 50±10  ps earlier D^{3}He reaction history timing (relative to DT) cannot be explained by average-ion hydrodynamic simulations and is attributed to fuel-ion species separation between the D, T, and ^{3}He ions during shock convergence and rebound. At the onset of the shock burn, inferred ^{3}He/T fuel ratio in the burn region using the measured reaction histories is much higher as compared to the initial gas-filled ratio. As T and ^{3}He have the same mass but different charge, these results indicate that the charge-to-mass ratio plays an important role in driving fuel-ion species separation during strong shock propagation even for these hydrodynamiclike plasmas.

Ion thermal decoupling and species separation in shock-driven implosions

Anomalous reduction of the fusion yields by 50% and anomalous scaling of the burn-averaged ion temperatures with the ion-species fraction has been observed for the first time in D^{3}He-filled shock-driven inertial confinement fusion implosions. Two ion kinetic mechanisms are used to explain the anomalous observations: thermal decoupling of the D and ^{3}He populations and diffusive species separation. The observed insensitivity of ion temperature to a varying deuterium fraction is shown to be a signature of ion thermal decoupling in shock-heated plasmas. The burn-averaged deuterium fraction calculated from the experimental data demonstrates a reduction in the average core deuterium density, as predicted by simulations that use a diffusion model. Accounting for each of these effects in simulations reproduces the observed yield trends.

First observations of nonhydrodynamic mix at the fuel-shell interface in shock-driven inertial confinement implosions

A strong nonhydrodynamic mechanism generating atomic fuel-shell mix has been observed in strongly shocked inertial confinement fusion implosions of thin deuterated-plastic shells filled with 3He gas. These implosions were found to produce D3He-proton shock yields comparable to implosions of identical shells filled with a hydroequivalent 50∶50 D3He gas mixture. Standard hydrodynamic mixing cannot explain this observation, as hydrodynamic modeling including mix predicts a yield an order of magnitude lower than was observed. Instead, these results can be attributed to ion diffusive mix at the fuel-shell interface.

A new compact, high sensitivity neutron imaging system

We have developed a new small neutron imaging system (SNIS) diagnostic for the OMEGA laser facility. The SNIS uses a penumbral coded aperture and has been designed to record images from low yield (10(9)-10(10) neutrons) implosions such as those using deuterium as the fuel. This camera was tested at OMEGA in 2009 on a rugby hohlraum energetics experiment where it recorded an image at a yield of 1.4 × 10(10). The resolution of this image was 54 μm and the camera was located only 4 meters from target chamber centre. We recently improved the instrument by adding a cooled CCD camera. The sensitivity of the new camera has been fully characterized using a linear accelerator and a (60)Co γ-ray source. The calibration showed that the signal-to-noise ratio could be improved by using raw binning detection.

Thomson scattering diagnostic for the measurement of ion species fraction

Simultaneous Thomson scattering measurements of collective electron-plasma and ion-acoustic fluctuations have been utilized to determine ion species fraction from laser produced CH plasmas. The CH(2) foil is heated with 10 laser beams, 500 J per beam, at the Omega Laser facility. Thomson scattering measurements are made 4 mm from the foil surface using a 30 J 2ω probe laser with a 1 ns pulse length. Using a series of target shots the plasma evolution is measured from 2.5 ns to 9 ns after the rise of the heater beams. Measuring the electron density and temperature from the electron-plasma fluctuations constrains the fit of the two-ion species theoretical form factor for the ion feature such that the ion temperature, plasma flow velocity and ion species fraction are determined. The ion species fraction is determined to an accuracy of ±0.06 in species fraction.

Experimental demonstration of X-ray drive enhancement with rugby-shaped hohlraums

Rugby-shaped hohlraums have been suggested as a way to enhance x-ray drive in the indirect drive approach to inertial confinement fusion. This Letter presents an experimental comparison of rugby-shaped and cylinder hohlraums used for D2 and D3He-filled capsules implosions on the Omega laser facility, demonstrating an increase of x-ray flux by 18% in rugby-shaped hohlraums. The highest yields to date for deuterium gas implosions in indirect drive on Omega (1.5x10{10} neutrons) were obtained, allowing for the first time the measurement of a DD burn history. Proton spectra measurements provide additional validation of the higher drive in rugby-shaped hohlraums.

Somatomedin-C/IGF-I, insulin and prolactin levels in Ullrich-Turner's syndrome

To clarify the pathogenesis of growth retardation in patients with Ullrich-Turner's syndrome (TS) we have investigated basal SmC/IGF-I, insulin and prolactin concentrations. Compared with 56 age matched healthy controls basal SmC/IGF-I concentration in 51 patients with TS older than 9-11 years was significantly lower (age group 13-14 years; TS 273 +/- 47 and controls 479 +/- 114 ng/ml). Mean basal prolactin level in 43 patients with TS (406 +/- 211 microU/ml) was significantly higher (p less than 0.01) than in 192 female controls (age 3-11 years; 264 +/- 176 microU/ml). Basal insulin concentration in 28 TS patients in comparison to 20 healthy children of a control group was significant higher (TS 18 +/- 8 microU/ml; controls 9 +/- 4 microU/ml; p less than 0.01). It seems that neither insulin nor prolactin are relevant stimulators of Smc/IGF-I in man, especially in patients with gonadal dysgenesis. Considering these results we speculate that despite higher prolactin and higher insulin levels in TS, the lower SmC/IGF-I concentrations may be predominantly related to the abnormal sex steroid secretion.

Glucose metabolism in children with renal failure: oral or intravenous glucose tolerance

There is debate about the most suitable test for investigation of glucose tolerance in children with chronic renal failure. We therefore studied the agreement between the two most commonly used glucose tolerance tests in 33 children with chronic renal failure (mean age 10.9+/-5.3 years, median GFR was 24 ml/min/1.73 m2). All children underwent an oral glucose tolerance test (OGTT) with blood sampling up to 180 minutes and after an oral load of 1.75 g/kg and a standard intravenous glucose tolerance test (IVGTT) using 0.5 g/kg i.v. The two tests were performed at an interval of 23+/-5 days, with 9 patients having the OGTT before and 24 after the IVGTT. In order to account for the differing glucose load, a subgroup of 19 patients also received a glucose infusion test (GIT) using a total of 1.75 g/kg i.v. On IVGTT, 27 patients had a normal and 6 had a pathological glucose decay constant (k-value). On OGTT, 12 patients had an impaired glucose tolerance (IGT) and 3 patients were diabetic according to WHO standard, and only 18 patients had a normal glucose tolerance. While there was good correlation between both glucose and insulin concentrations between IVGTT and OGTT, only when reapplying the WHO criteria of a glucose concentration below 6.7 mmol/l to the concentration measured 180 minutes instead of 120 minutes after oral glucose load, the agreement between the two tests improved. The proportion of normal findings on GIT when compared to OGTT was identical. When using the appropriate definitions for normal and abnormal carbohydrate tolerance, interestingly the insulin (IRI) concentrations on OGTT were not discriminative between the normal and the pathological group, whereas IRI first phase secretion on IVGTT and IRI 0-180 AUC on GIT did discriminate. We conclude that the standard WHO OGTT criteria may have to be reconsidered in children with chronic renal failure and that OGTT should be extended to 180 minutes. The IVGTT, particularly when insulin early phase secretion (at 0, 1, 3 and 5 minutes) is also monitored, provides a reliable test for assessing glucose tolerance in children with chronic renal failure.

Glucose tolerance and insulin secretion in children before and during recombinant growth hormone treatment

This study evaluates glucose metabolism and insulin secretion in children with Ullrich-Turner syndrome (UTS), chronic renal failure (CRF) and kidney transplantation (KTx) with rh GH therapy using an intravenous glucose infusion test. Before treatment, glucose AUC was significantly increased in all patient groups when compared to normal controls. Both the early and second phases of insulin secretion were not altered. During treatment, elevated glucose AUC showed a further increase in patients with KTx but not in patients with CRF or UTS. Both the early and second insulin secretion phases rose significantly in UTS and were transiently elevated after 6 and 12 months of therapy in patients with CRF and KTx. We conclude that growth hormone therapy aggravates alteration of glucose metabolism in patients with KTx and not in children with CRF and UTS. Progressive hyperinsulinemia occurred only in patients with UTS.

Tacrolimus reversibly reduces insulin secretion in paediatric renal transplant recipients

BACKGROUND

Conflicting reports exist about the mechanism of tacrolimus-induced post-transplant diabetes mellitus.

METHODS

We analysed intravenous glucose tolerance tests (IVGTT) of 14 paediatric renal transplant recipients on cyclosporin (CsA) microemulsion and 15 patients on tacrolimus (FK506). The groups were similar in age (13.2+/-4.2 vs 13.0+/-3.7 years), body mass index, serum creatinine concentrations (96+/-60 vs 97+/-44 micromol/l), time after renal transplantation, and cumulative steroid dose over 12 weeks prior to the test (3.4 vs 3.5 mg/m(2)/day, NS, Mann-Whitney). Parameters of glucose tolerance included glucose, insulin, C-peptide concentrations, and HbA1c. The mean concentrations of the primary immunosuppressant were similar to treatments employed in other centres (CsA 165+/-59 ng ml and FK506 7. 5+/-2.2 ng ml).

RESULTS

Baseline glucose concentrations were significantly higher on FK506 therapy compared with CsA microemulsion therapy. Baseline insulin concentrations and C-peptide concentrations were identical in both treatment groups. FK506 trough levels correlated negatively with k values (glucose constant decay) in the FK506 group. There was a significant reduction of the insulin first-phase concentrations, both after 1 min and after 3 min in the FK506 group compared with the CsA group (112+/-17 vs 237+/-57 microU/ml, P=0.034). In patients with repetitive IVGTTs, glucose constant decay and insulin production improved after lowering FK506 whole-blood trough levels.

CONCLUSIONS

We conclude that post-transplant glucose intolerance could be due to a dose-dependent, direct effect of FK506 on the pancreatic beta cell function, which can be controlled by dose reduction.

Growth retardation in Turner syndrome: aneuploidy, rather than specific gene loss, may explain growth failure

The etiology of short stature (SST) in Turner syndrome (TS) is still a subject of speculation. A variety of hypotheses have been put forward, from SST as a result of increased intrauterine tissue pressure after fetal lymphedema to haploinsufficiency of a specific growth gene(s). These hypotheses have various statistical-auxological implications on the growth distribution in TS. Empirical research has provided no clear evidence for any of these theories, but the well known correlation between patients' and midparental height (MPH) could be established. The influence of undetected mosaic status has often been cited as a major problem in the investigation of growth in TS. However, an assessment of mosaic status (simultaneous analysis of karyotype and phenotype) and its effect on growth with inclusion of MPH has been not yet carried out for a large sample. The aim of this study was to evaluate growth and its complex relationship to mosaic status and MPH in TS. In a mixed cross-sectional and longitudinal study we retrospectively analyzed the auxological and clinical data of 447 patients with a pure loss of X-chromosomal material (n = 381 with 45,X0; n = 66 mosaics). The 447 patients were selected from a series of 609 consecutive patients with TS. To assess the effect of mosaic status on growth, we computed a bifactorial analysis of variance (phenotype, karyotype), including MPH as a covariate. In line with the mosaic hypothesis, we found a correlation between individual loss of X-chromosomal material and phenotypical expressivity. In contrast, no correlation was found with respect to growth. With respect to MPH, we found growth retardation (GR) even in those patients with "normal" height above the third percentile (-2 or more SD score). The interindividual variance of GR in TS (comparable to growth variance in the normal population) seems to be unrelated to other TS-specific factors (e.g. mosaic status or single gene loss). Instead, both interindividual variance and the global growth shift distribution are best explained by the presence of an unspecific aneuploidic effect. Furthermore, consideration of patient height in relation to MPH should lead to a better understanding of the nature of GR in TS than the commonly used, strictly qualitative definition of SST.

Slowly deteriorating insulin secretion and C-peptide production characterizes diabetes mellitus in infantile cystinosis

Infantile cystinosis, a rare lysosomal storage disease of cystine, leads to Fanconi syndrome and end-stage renal failure. After renal transplantation, no recurrence of the disease occurs in the graft, but other organ involvement becomes evident later in life. Diabetes mellitus has been associated with cystinosis, but the mechanisms of impaired glucose tolerance have not yet been characterized. Here, we studied glucose tolerance, glucose constant decay (k-values), insulin and C-peptide by intravenous glucose tolerance test (IVGTT) in eight patients with infantile cystinosis (three with impaired GFR (CRF) and five after kidney transplantation (KTX)). For comparison, 15 age-matched children with CRF and 15 age-matched KTX patients were analysed. Both early and second insulin secretion phases were diminished in patients with infantile cystinosis, whereas in CRF, k-values were no different from control patients. After renal transplantation, k-values were significantly lower in cystinotic patients with a markedly reduced early insulin secretion phase. There was a significant negative correlation between k-values and age in patients with cystinosis. Repetitive IVGTTs in these patients demonstrated progressive but rather slow loss of first phase insulin secretion and C-peptide production, suggesting a slowly reducing secretion potential of the beta cell due to cystine storage.

CONCLUSION

Unlike type I diabetes mellitus, glucose intolerance in patients with infantile cystinosis is characterized by a slow, progressive loss of insulin secretion and C-peptide production. For these patients, the data indicate a 50% risk of developing glucose intolerance by the age of 18 years. We recommend to perform intravenous glucose tolerance tests at 5-year intervals.

Reversible diabetes mellitus during growth hormone therapy in chronic renal failure

A 12-year-old girl with short stature due to idiopathic Fanconi syndrome and chronic renal failure was treated with recombinant human growth hormone (rhGH). There was no family history of diabetes mellitus and the glucose tolerance before treatment was normal. Intravenous glucose tolerance tests were performed before, during and after treatment. Two months after starting rhGH the early phase of insulin secretion (1-+3-min values) was diminished, and the patient developed manifest diabetes mellitus with hyperglycemia and an elevated hemoglobin A1c. Following discontinuation of rhGH, glucose tolerance slowly returned to normal.

Stimulation of nitrogen and whole-body protein metabolism in growth hormone-deficient children by recombinant human growth hormone: relationship to growth

The effect of a mammalian-cell-derived recombinant human growth hormone (rhGH) on nitrogen and whole-body protein metabolism was assessed in 12 children with complete growth hormone (GH) deficiency. All the patients received single oral doses of 15N-glycine (95 atom % 15N), 20 mg/kg body weight, prior to and following 7 days of treatment with rhGH, 1.7 IU/m2 body surface area (BSA) per day, administered subcutaneously. Prior to rhGH, mean urinary 15N-nitrogen excretion was 42.8 +/- 8% of the administered dose, which fell significantly to 22.8 +/- 7% during rhGH administration (p < 0.0001). Stimulation of protein metabolism by rhGH resulted in a protein net gain rate of 1.1 +/- 0.4 g/kg/day, which was significantly higher than the 0.6 +/- 0.5 g/kg/day rate seen prior to rhGH (p < 0.001). In patients subsequently placed on daily subcutaneous injections of rhGH 1.7 IU/m2 BSA, mean height velocity standard deviation score (HV SDS) for chronological age significantly increased from -3.8 +/- 2.6 to +8.5 +/- 3.1 and +3.3 +/- 2.2, during the 1st and 2nd years of treatment, respectively. However, there was no correlation between the long-term response to rhGH treatment and the short-term changes in nitrogen or protein metabolism in GH-deficient children.

The hyperinsulinaemic hypoglycaemias in infancy: a study of six cases

The aim of the present study was to evaluate various functional tests for the differentiation of hyperinsulinaemic hypoglycaemia. The pathophysiological and histological findings in six infants, aged 2-7 months, with persistent hyperinsulinaemic hypoglycaemia are described. Islet cell adenoma was found in four infants and pancreatic nesidioblastosis in two others. Circulating levels of blood glucose (BG), immunoreactive insulin and C-peptide immunoreactivity were measured under basal conditions and during both stimulation and suppression. The diagnosis of hyperinsulinaemia was made by estimation of the BG/serum insulin ratio, which was the most important diagnostic criterion of hyperinsulinism. Control subjects of comparable age showed a ratio of 8.3 +/- 4.4 (range 4.1-13.3), whereas the six patients had values between 0.3 and 5.1. At least four determinations with ratios lower than 2.6 were necessary for confirming the diagnosis. Preoperatively we performed oral glucose tolerance, diazoxide infusion, somatostatin infusion and C-peptide suppression tests. It is suggested that the various function tests, especially the suppression tests, do not differentiate hyperinsulinism caused by an adenoma from that caused by diffuse pancreatic nesidioblastosis.

Measurement of insulin in human sera using a new RIA kit. 1. Insulin determination in the absence of insulin antibodies--conventional assay and micro modification

A sensitive and versatile radioimmunoassay (RIA) for insulin was established using human insulin standard, a specific guinea pig anti-insulin antiserum and rabbit anti-guinea pig serum. Radioiodination was performed according to a modified chloramine T method. Tracer preparations were used for as long as 6 weeks after iodination. The standard curve ranges from 0.044 to 1.2 nmol/l. The intra-assay coefficient of variation (CV) was 3-5% and the inter-assay CV was 6-9% in the optimal range between 0.4 and 0.9 nmol/l. The average recovery of human insulin added to plasma or serum samples was 100.2 +/- 2.0% (n = 38) and 100.1 +/- 1.9% (n = 42), respectively. In addition to human insulin, porcine, canine, rabbit and bovine insulin can also be determined but not rat or mouse insulin. The cross-reactivity of the antiserum with porcine proinsulin was found to be 40% on the molar basis. The range of mean fasting plasma insulin concentrations in healthy subjects and under various pathological conditions were estimated.

Clinical and metabolic studies in children of diabetic-mothers

Children of diabetic mothers are a high-risk group. The perinatal mortality and the malformation frequency of the newborns as well as the psychosomatic, somatic and speech development during childhood until the age of 15 were statistically significantly influenced by quality of metabolic compensation, toxaemia and urinary tract infections during pregnancy. To evaluate the diabetogenic risk in children of diabetic mothers metabolic follow-up studies were performed. A statistically significant insulin-high-response without disturbed carbohydrate tolerance was seen in 25% after intravenous glucose infusion and in 28% after oral glucose load. 17% exhibited a paradoxical growth hormone reaction, while the intravenous glucose tolerance and the insulin secretion was in the normal range. Both symptoms could be early diabetic signs in children of diabetic mothers. The oGTT had pathological results in 18% and the glucose infusion test in 8%.

Determination of total insulin (TIRI) in plasma of insulin-treated diabetics and newborn infants of insulin-treated diabetic mothers

Plasma of insulin-treated diabetics and of newborn infants of insulin-treated diabetic mothers contains insulin antibodies which invalidates the radioimmunoassay of insulin. Therefore, the endogenous insulin antibody complex must be splitted at a pH lower than 5 and the total IRI (TIRI) is separated by ethanol extraction. It was investigated the recovery rate in dependence upon plasma volume used for extraction. By reduction of used plasma volume from 500 to 200 mul per extraction the recovery rate was increased from 65.1 +/- 8.4 to 88.3 +/- 4.2% (mean +/- SEM). The low plasma volume of 200 mul for TIRI extraction made it possible to determine TIRI during glucose loads of newborn infants. To eliminate different conditions of incubation for standard and unknown plasma samples the TIRI levels were computed by means of so-called "extracted" standard curve, obtained with extracted insulin from standard insulin dilution in insulin-free pooled human plasma. Using the described method a temporary regeneration of insulin secretion of a newly diagnosed juvenile diabetic after insulin treatment could be shown. In contrast to newborn infants of healthy mothers a biphasic/insulin release was found during the intravenous glucose loads in newborn infants of insulin-treated diabetic mothers.

Morphologie der Plazenta und neonatale Acidose bei mütterlichem Diabetes mellitus

Comparing the morphological findings of the placentas of acidotically born babies of diabetic mothers with non-acidotically born ones, we could find an extensive correlation of macroscopically detectable changes of the placentas (diminution of placental weight, insertio velamentosa of umbilical cord, aplasia of one umbilical artery) and histological findings (severity of diabetic maturation disturbances, size of villi) with the degree of the neonatal acidosis. With the severity of acidosis, the oedematosis of the placentas increases, too. When diabetic pregnancy is complicated by the EPH gestosis, a stronger fibrosis of the chorionic villi results. The oedematosis of the stroma recedes. The oedema of the placenta is in most cases correlated with the clinical appearance of the diabetic fetopathy (cushingoid newborn). According to our findings in cases complicated by the EPH gestosis, the oedematosis of the placenta and to a minor extent the cushingoid of the newborn are to be found more seldom.