Note: Velocity map imaging the scattering plane of gas surface collisions.

The ability of gas-surface dynamics studies to resolve the velocity distribution of the scattered species in the 2D scattering plane has been limited by technical capabilities and only a few different approaches have been explored in recent years. In comparison, gas-phase scattering studies have been transformed by the near ubiquitous use of velocity map imaging. We describe an innovative means of introducing a dielectric surface within the electric field of a typical velocity map imaging experiment. The retention of optimum velocity mapping conditions was validated by measurements of iodomethane-d3 photodissociation and SIMION calculations. To demonstrate the system's capabilities, the velocity distributions of ammonia molecules scattered from a polytetrafluoroethylene surface have been measured for multiple product rotational states.

A Multipronged Comparative Study of the Ultraviolet Photochemistry of 2-, 3-, and 4-Chlorophenol in the Gas Phase.

The S1((1)ππ*) state of the (dominant) syn-conformer of 2-chlorophenol (2-ClPhOH) in the gas phase has a subpicosecond lifetime, whereas the corresponding S1 states of 3- and 4-ClPhOH have lifetimes that are, respectively, ∼2 and ∼3-orders of magnitude longer. A range of experimental techniques-electronic spectroscopy, ultrafast time-resolved photoion and photoelectron spectroscopies, H Rydberg atom photofragment translational spectroscopy, velocity map imaging, and time-resolved Fourier transform infrared emission spectroscopy-as well as electronic structure calculations (of key regions of the multidimensional ground (S0) state potential energy surface (PES) and selected cuts through the first few excited singlet PESs) have been used in the quest to explain these striking differences in excited state lifetime. The intramolecular O-H···Cl hydrogen bond specific to syn-2-ClPhOH is key. It encourages partial charge transfer and preferential stabilization of the diabatic (1)πσ* potential (relative to that of the (1)ππ* state) upon stretching the C-Cl bond, with the result that initial C-Cl bond extension on the adiabatic S1 PES offers an essentially barrierless internal conversion pathway via regions of conical intersection with the S0 PES. Intramolecular hydrogen bonding is thus seen to facilitate the type of heterolytic dissociation more typically encountered in solution studies.

Screening for hyperglycaemia in pregnancy: a rapid update for the National Screening Committee.

BACKGROUND: Screening for gestational diabetes has long been a controversial topic. A previous Health Technology Assessment (HTA) report reviewed literature on screening for gestational diabetes mellitus (GDM) and assessed the case for screening against the criteria set by the National Screening Committee. OBJECTIVE: To update a previous HTA report which reviewed the literature on screening for GDM by examining evidence that has emerged since that last report, including the Australian Carbohydrate Intolerance Study in Pregnant Women (ACHOIS), the Maternal and Fetal Medicine Units Network (MFMUN) trial and the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study. To review data on recent trends in maternal age at birth and on the prevalence of overweight and obesity and the effect on prevalence of GDM. DATA SOURCES: A systematic review and meta-analysis of the literature was carried out. The bibliographic databases used were MEDLINE (1996 to January 2009), EMBASE (1996 to December 2009), the Cochrane Library 2008 issue 4, the Centre for Reviews and Dissemination database and the Web of Science. REVIEW METHODS: For the review of treatment with oral drugs versus insulin, a full systematic review and meta-analysis was carried out. The results of the ACHOIS, MFMUN and HAPO studies were summarised and their implications discussed. Findings of a selection of other recent studies, relevant to the continuum issue, were summarised. Some recent screening studies were reviewed, including a particular focus on studies of screening earlier in pregnancy. RESULTS: The HAPO results showed a linear relationship between plasma glucose and adverse outcomes - there is a continuum of risk with no clear threshold which could divide women into those with gestational diabetes and those without. There was good evidence from trials and the meta-analysis that women who fail to control hyperglycaemic in pregnancy on lifestyle measures alone can be safely and effectively be treated with oral agents, metformin or glibenclamide, rather than going directly to insulin. Evidence showed few differences in results between glibenclamide and insulin and metformin and insulin. The exceptions were that there was less maternal hypoglycaemia with glibenclamide, but less neonatal hypoglycaemia and lower birthweight with insulin, and there was less maternal weight gain with metformin. The ACHOIS and MFMUN trials showed reductions in perinatal complications among infants born to mothers who were provided with more intensive dietary advice, blood glucose monitoring and insulin when required. The HAPO study demonstrated adverse outcomes over a much wider range of blood glucose (BG) than the traditional definition of GDM. In the HAPO study, no one measure of BG came out as being clearly the best, although fasting plasma glucose (FPG) was as good as any, and had advantages of being more convenient than an oral glucose tolerance test (OGTT), but correlations between fasting and post-load levels were quite poor. Two screening strategies dominated; (1) selection by the American Diabetes Association criteria followed by the 75-g OGTT [incremental cost-effectiveness ratio (ICER) 3678 pounds], and (2) selection by high-risk ethnicity followed by the 75-g OGTT (ICER 21,739 pounds). Studies indicated that costs are about 1833 pounds higher for pregnancies complicated by gestational diabetes, suggesting that prevention would be worthwhile. LIMITATIONS: Not all of the HAPO results have been published, and none of the reviewed economic studies resolved the most difficult issue - at what level of BG does intervention become cost-effective? CONCLUSIONS: The evidence base has improved since the last HTA review in 2002. There is now good evidence for treatment of oral drugs instead of insulin and it looks increasingly as if FPG could be the test of choice. However some key uncertainties remain to be resolved, which can be done by further analysis of the already collected HAPO data and by using the UK model used in developing the NICE guidelines to assess the cost-effectiveness of intervention in each of the seven HAPO categories.

Diabetes classification: grey zones, sound and smoke: Action LADA 1.

Diseases gain identity from clinical phenotype as well as genetic and environmental aetiology. The definition of type 1 diabetes is clinically exclusive, comprising patients who are considered insulin dependent at diagnosis, whilst the definition of type 2 diabetes is inclusive, only excluding those who are initially insulin dependent. Ketosis-prone diabetes (KPD) and latent autoimmune diabetes in adults (LADA) are each exclusive forms of diabetes which are, at least initially, clinically distinct from type 2 diabetes and type 1 diabetes, and each have a different natural history from these major types of diabetes.KPD can be diagnosed unequivocally as diabetes presenting with the categorical clinical feature, ketoacidosis. In contrast, LADA can be diagnosed by the co-occurrence of three traits, not one of which is categorical or exclusive to the condition: adult-onset non-insulin-requiring diabetes, an islet autoantibody such as glutamic acid decarboxylase autoantibodies (GADA) or cytoplasmic islet cell autoantibodies (ICA), and no need for insulin treatment for several months post-diagnosis. But while some would split diabetes into distinct subtypes, there is a strong case that these subtypes form a continuum of varying severity of immune and metabolic dysfunction modified by genetic and non-genetic factors. This article discusses the nature of disease classification in general, and KPD and LADA in particular, emphasizing the potential value and pitfalls in classifying diabetes and suggesting a need for more research in this area.

Prediabetes and the big baby.

The concept of prediabetes has come to the fore again with the worldwide epidemic of Type 2 diabetes. The careful observations of W. P. U. Jackson and his colleagues in Cape Town, South Africa 50 years ago still deserve attention. Maternal hyperglycaemia cannot be the only cause of fetal macrosomia, and the pathophysiological reason for the unexplained stillbirth in late diabetic pregnancy still eludes us. The biochemical concepts of 'facilitated anabolism' and 'accelerated starvation' were developed by Freinkel as explanations of the protective mechanisms for the baby during the stresses of pregnancy. Some of these nutritional stresses may also occur in the particular form of early childhood malnutrition known in Africa as kwashiorkor, where subcutaneous fat deposition, carbohydrate intolerance, islet hyperplasia and sudden death may follow a period of excess carbohydrate and deficient protein intake. Different feeding practices in different parts of the world make comparisons uncertain, but there is evidence for insulin resistance in both the macrosomic fetus of the hyperglycaemic mother and in the child with established kwashiorkor. These adaptive changes in early development may play both a physiological and a pathological role. Worldwide studies of hyperglycaemia in pregnancy are gradually establishing acceptable diagnostic criteria, appropriate screening procedures and an evidence base for treatment. Nevertheless the challenge of prediabetes and the big baby is still with us--in Jackson's words--'diabetes mellitus is a fascinating condition-the more we know about it the less we understand it'.

Peptide binding at the GLP-1 receptor.

The receptor for GLP-1 [glucagon-like peptide-1-(7-36)-amide] is a member of the 'Family B' of GPCRs (G-protein-coupled receptors) comprising an extracellular N-terminal domain containing six conserved cysteine residues (the N-domain) and a core domain (or J-domain) comprising the seven transmembrane helices and interconnecting loop regions. According to the two-domain model for peptide binding, the N-domain is primarily responsible for providing most of the peptide binding energy, whereas the core domain is responsible for binding the N-terminal region of the peptide agonists and transmitting the signal to the intracellular G-protein. Two interesting differences between the binding properties of two GLP-1 receptor agonists, GLP-1 and EX-4 (exendin-4), can be observed. First, while GLP-1 requires its full length to maintain high affinity, the eight N-terminal residues of EX-4 can be removed with little reduction in affinity. Secondly, EX-4 (but not GLP-1) can bind to the fully isolated N-domain of the receptor with an affinity matching that of the full-length receptor. In order to better understand these differences, we have studied the interaction between combinations of full-length or truncated ligands with full-length or truncated receptors.

Goat's rue - French lilac - Italian fitch - Spanish sainfoin: gallega officinalis and metformin: the Edinburgh connection.

The hypoglycaemic drug metformin is derived from galegine, which is naturally found in Goat's rue (gallega officinalis). The plant is spreading northwards in the UK.

Trial introduction of the Willis dropped ovary technique for spaying cattle in northern Australia.

OBJECTIVE: To compare the Willis dropped ovary technique with traditional spaying methods in extensive beef cattle herds in northern Australia. PROCEDURE: Three field trials were conducted simultaneously at different sites in northern Australia in 1996-97. Brahman and Brahman-Shorthorn cross heifers (n = 219, 2 years, 250 to 378 kg) and cows (n = 211, 3 to 16 years, 256 to 540 kg) were allocated by stratified randomisation to three treatments: spaying using the Willis dropped ovary technique (WDOT); spaying using traditional paralumbar and vaginal methods; and unspayed. Following these procedures, these nonpregnant, nonlactating cattle were then exposed to bulls (4 per 100 females) under extensive rangeland conditions for 12 months during which time weight, body condition, pregnancy and ovarian function were monitored and compared. RESULTS: Pregnancy rates varied from 60 to 90% for entire heifers and 80 to 100% for entire cows depending on site. The traditional spay methods were 100% successful in preventing pregnancy; the WDOT was 92 to 97% effective, depending on operator experience. The number of deaths was the same or higher in Willis spayed animals than other groups. Weight changes were similar in all groups at the three sites over the trial period. The time taken to spay using the WDOT was similar to or less than that required for the traditional methods. Uterine abnormalities were not observed in animals spayed with the WDOT, there were however 30 (12.4%) animals where excision of the ovary was incomplete; the still-attached ovarian remnant presumably accounting for the three pregnant animals in this group. CONCLUSION: The WDOT suffers from requiring a high degree of skill in transrectal ovarian manipulation. There were more deaths and more pregnancies than with traditional spay methods. More experienced operators can be expected to achieve lower mortalities, better contraception and higher processing rates. Pregnancy will occur as a consequence of ovarian remnants unless care is taken to ensure removal of the entire ovary.

Cardiovascular and metabolic abnormalities in the offspring of diabetic pregnancy.

AIMS/HYPOTHESIS: Maternal fuel metabolism is known to exert long range effects on the later development of children of diabetic mothers. Recently cardiovascular disease in adult life has been linked retrospectively with foetal malnutrition. The aim of this study was to identify whether markers for fuel-related cardiovascular programming exist for the offspring of diabetic pregnancy. METHODS: Sixty-one children aged 5 to 11 years, of mothers with Type I (insulin-dependent) diabetes mellitus were compared with 57 randomly selected control children of non-diabetic mothers similar in age, sex and social class. Fasting blood was taken for plasma glucose, insulin, lipids, IGF-1, plasminogen activating inhibitor 1 (PAI-1) and the adhesion molecules ICAM-1, VCAM-1 and E-Selectin. RESULTS: Fasting glucose and insulin were similar in the two groups. Differences existed between the offspring of diabetic and non-diabetic pregnancies (mean +/- SD) for total cholesterol (4.45+/-0.56 vs 4.18+/-0.66, p=0.03 ), LDL cholesterol (2.73+/-0.49 vs 2.39+/-0.54, p=0.001), Cholesterol-to-HDL ratio (3.41+/-0.76 vs 3.09+/-0.73, p=0.03), IGF-1 (22.5+/-7.3 vs 19.3+/-8, p=0.04), PAI-1 (20.1+/-6.2 vs 14.9+/-7.3, p=0.000), VCAM-1 (1852+/-444 vs 1509+/-385, p=0.000) and E-Selectin (geometric mean; 83.1 vs 63.9, p=0.001). CONCLUSION/INTERPRETATION: These results indicate that important differences in cardiovascular risk factors exist between glucose-tolerant children of Type I diabetic and non-diabetic mothers, even in childhood. These data suggest that offspring of diabetic mothers might be at an increased risk for the development of vascular disease in later life.

Effects of low-dose oral hydrocortisone replacement versus short-term reproduction of physiological serum cortisol concentrations on insulin action in adult-onset hypopituitarism.

OBJECTIVE: Hypercortisolism is associated with impaired glucose tolerance and insulin resistance. For many years hydrocortisone 30 mg was the standard total daily replacement dose in adult hypopituitarism. The use of this conventional dose has now been shown to result in mild biochemical hypercortisolism and might contribute to the increased cardiovascular risk reported in hypopituitarism. The use of lower doses of hydrocortisone replacement therapy might prevent some of the adverse metabolic effects seen with conventional doses. PATIENTS: In a randomized crossover study we assessed peripheral and hepatic insulin action in 15 ACTH-deficient patients with normal glucose tolerance on two occasions while receiving either a low-dose oral hydrocortisone replacement (LOR) therapy (15 mg at 0800, 5 mg at 1700) or a physiological hydrocortisone infusion (PHI), which achieved physiological serum cortisol concentrations. RESULTS: Exogenous glucose infusion rates required to maintain euglycaemia were similar for the LOR and the PHI protocols (26.2 +/- 0.4 vs. 23.8 +/- 0.6 micromol/kg/min, respectively). Endogenous glucose production was also similar (12.0 +/- 2.5 vs. 11.6 +/- 2.4 micromol/kg/min, respectively) and in the post-absorptive state suppressed to a similar extent following insulin (4.5 +/- 2.0 vs. 5.1 +/- 3.1 micromol/kg/min). CONCLUSION: Hydrocortisone replacement therapy at a dose of 15 mg with breakfast, 5 mg with evening meal does not increase peripheral or hepatic insulin resistance when compared to a hydrocortisone infusion designed to simulate physiological serum cortisol concentrations.

The effects on insulin action in adult hypopituitarism of recombinant human GH therapy individually titrated for six months.

There is controversy about the effect of replacement GH on insulin action in adult hypopituitary patients. GH replacement calculated from weight leads to unacceptable side effects in some patients. Recent studies suggest it should be individually titrated in adults using serum IGF-I levels. We have assessed the effect of titrated GH replacement on peripheral and hepatic insulin action in 13 adult-onset hypopituitary patients (8 males and 5 females; ages 47 +/- 10 yr, mean duration of hypopituitarism 6 yr) with confirmed GH deficiency (GHD; maximum GH <5 mU/liter during insulin induced hypoglycemia), ACTH deficiency, and normal glucose tolerance. All patients were on stable hydrocortisone replacement (15 mg with breakfast, 5 mg with evening meal) for at least 2 months before the trial. Insulin action was assessed by the euglycemic hyperinsulinemic glucose clamp technique (1 mU/kg x min) before and after 6 months of GH therapy. GH was started at 0.8 IU sc daily and titrated monthly until the serum IGF-I increased to within 1-2 SD of the mean of normal age-matched controls. Body mass index did not change significantly during the 6 months of GH therapy. Fasting plasma glucose and HbA1c increased significantly after 6 months (5.2 +/- 0.0 vs. 5.5 +/- 0.0 mmol/liter, P < 0.0001, and 4.5 +/- 0.1 vs. 4.7 +/- 0.1%, P < 0.0005, respectively). There was no increase in fasting serum insulin (51.6 +/- 10.2 vs. 60.0 +/- 10.2 pmol/liter, P = 0.12). Exogenous glucose infusion rates required to maintain euglycemia were similar after GH (23.0 +/- 0.4 vs. 21.1 +/- 0.3 micromol/kg x min, P = 0.6). Endogenous glucose production in the fasting state was also unchanged following GH (11.8 +/- 0.7 vs.12.3 +/- 0.9 micromol/kg x min, P = 0.5) and suppressed to a similar extent following insulin (4.4 +/- 0.8 vs. 5.5 +/- 0.8 micromol/kg x min, P = 0.3). In summary, GH therapy for 6 months, with serum IGF-I maintained in the upper physiological range, increased fasting plasma glucose and HbA1c. There was no effect on peripheral or hepatic insulin sensitivity. Patients receiving GH therapy require long-term monitoring of glucose tolerance.

Obstetric and diabetic care for pregnancy in diabetic women: 10 years outcome analysis, 1985-1995.

AIM: Ten-year outcome analysis of all pregnancies in diabetic women in a population of 1.5 million people. METHODS: Ascertainment of patients through the regional obstetrical computer, and by direct contact with each obstetrical unit. Retrospective assessment of early miscarriage of pregnancy from hospital records. Data are presented for the six smallest obstetrical units, the four smaller district hospitals, two larger teaching hospitals and for the regional referral centre. RESULTS: Nine hundred and eighty-six fetal outcomes were identified, 753 in mothers treated with insulin before the pregnancy, 131 in mothers in whom insulin was started for the first time during the pregnancy and 102 in mothers treated by diet only. Overall perinatal mortality rates were 35.8 per 1000 for those mothers booked and delivered at a local maternity unit, 28.9 per 1000 for those booked and delivered at the regional centre, but 75.0 per 1000 for those who had booked locally but were transferred to the centre mid-pregnancy. Information on blood glucose control before and during pregnancy was relatively poorly documented. For the available data at the regional centre, only 160 of the 416 mothers had an identifiable preconception HbA1c measurement (mean 7.9%, range 3.3-16.8%): at booking 360 of these mothers had a mean HbA1c of 7.5% and by the third trimester mean HbA1c was 6.3% (range 3.3-13.2%). CONCLUSIONS: The outcome of pregnancy in a diabetic mother in Northern Ireland remains a higher risk than for the general population. There is evidence that results in the regional centre are better, but problems arise when transfers occur mid-pregnancy. Measurement and recording of blood glucose control at all stages before and during pregnancy is incomplete. Diabet. Med. 18, 546-553 (2001)

Laboratory and clinical experience in 55 patients with macroprolactinemia identified by a simple polyethylene glycol precipitation method.

PRL exists in different forms in human serum. The predominant form is little PRL (molecular mass 23 kDa) with smaller amounts of big PRL (molecular mass 50--60 kDa) and at times big big or macroprolactin (molecular mass 150--170 kDa). The frequency and clinical consequences of macroprolactinemia have not been clearly established, mainly because of difficulty in identifying these patients biochemically. This previously required the use of gel filtration chromatography, which could not be used routinely. Recently, a screening test using polyethylene glycol (PEG) has been used to identify macroprolactin in serum. Consequently, this study was designed to examine the use of PEG precipitation in the identification of patients with a predominance of macroprolactin and to establish the clinical characteristics of such a cohort. Over 12 months, 18,258 requests for serum PRL were received and of these 1225 patients had a serum PRL more than 700 mU/L. A total of 322 of these patients (26%) had a percentage recovery after PEG precipitation of less than 40%, thus indicating the presence of a predominance of macroprolactin. Fifty-five of these patients were referred for detailed clinical assessment. Symptoms typical of hyperprolactinemia were not common in this cohort. None had sustained amenorrhea and eight have had oligomenorrhea at age less than 40 yr. One had galactorrhea. All had pituitary imaging, and four had a microadenoma with none having a macroadenoma. PEG precipitation allows easy identification of macroprolactin in routine clinical practice. As the clinical consequences of this entity at this stage seem relatively benign, referral and intensive investigation of these patients may not be necessary. However, follow-up of a large cohort is required to ensure that the long-term outlook is likewise benign. This would have important implications for both patients and healthcare systems.

Prevalence of diabetes and impaired glucose tolerance in adult hypopituitarism on low dose oral hydrocortisone replacement therapy.

OBJECTIVE: The conventional dosage of hydrocortisone, used for many years in the management of hypopituitarism (30 mg per day), has now been shown to be more than is physiologically necessary. On this conventional corticosteroid therapy studies have demonstrated an increased prevalence of diabetes and impaired glucose tolerance, which may contribute to the increased vascular morbidity and mortality reported in the condition. In these studies no information is available on oral glucose tolerance test (OGTT) timing in relation to administration of oral steroid and variable hydrocortisone doses were employed. PATIENTS: In order to assess glucose tolerance in patients treated with lower, more physiological doses, we performed a 75-g OGTT at least 1 month after hydrocortisone therapy was adjusted to 15 mg at 0800 h and 5 mg at 1700 h in 45 adult onset hypopituitary patients (30 M, 15 F). Mean (+/- SD) duration of hypopituitarism was 12 +/- 10 years, mean age 52 +/- 14 years and BMI 29.3 +/- 5.1 kg/m2. All were on hydrocortisone, 43 on thyroxine, 31 on sex steroids, 9 on desmopressin and 33 had documented growth hormone deficiency. Hydrocortisone 15 mg was taken at 0800 and the OGTT commenced at 0900. RESULTS: Using standard WHO criteria 36 patients (80%) had normal glucose tolerance, 1 (2%) had newly diagnosed diabetes and 8 (18%) had impaired glucose tolerance. Using the recently announced American Diabetes Association criteria for diagnosis 96% had normal glucose tolerance, 2% had diabetes and 2% impaired fasting glucose. CONCLUSION: The markedly reduced prevalence of diabetes and impaired glucose tolerance on lower hydrocortisone replacement doses in our series of patients with hypopituitarism, not previously known to be diabetic, is of great interest. This lower prevalence may eventually result in reduced vascular complication rates.

Subcellular distribution and membrane topology of the mammalian concentrative Na+-nucleoside cotransporter rCNT1.

The rat transporter rCNT1 is the archetype of a family of concentrative nucleoside transporters (CNTs) found both in eukaryotes and in prokaryotes. In the present study we have used antibodies to investigate the subcellular distribution and membrane topology of this protein. rCNT1 was found to be expressed predominantly in the brush-border membranes of the polarized epithelial cells of rat jejunum and renal cortical tubules and in the bile canalicular membranes of liver parenchymal cells, consistent with roles in the absorption of dietary nucleosides, of nucleosides in the glomerular filtrate, or of nucleosides arising from the action of extracellular nucleotidases, respectively. The effect of endoglycosidase F treatment on wild-type and mutant rCNT1 expressed in Xenopus oocytes revealed that the recombinant transporter could be glycosylated at either or both of Asn605 and Asn643, indicating that its C terminus is extracellular. In contrast, potential N-glycosylation sites introduced near the N terminus, or between putative transmembrane (TM) helices 4 and 5, were not glycosylated. The deduced orientation of the N terminus in the cytoplasm was confirmed by immunocytochemistry on intact and saponin-permeabilized Chinese hamster ovary cells expressing recombinant rCNT1. These results, in conjunction with extensive analyses of CNT family protein sequences using predictive algorithms, lead us to propose a revised topological model, in which rCNT1 possesses 13 TM helices with the hydrophilic N-terminal and C-terminal domains on the cytoplasmic and extracellular sides of the membrane, respectively. Furthermore, we show that the first three TM helices, which are absent from prokaryote CNTs, are not essential for transporter function; truncated proteins lacking these helices, derived either from rCNT1 or from its human homolog hCNT1, were found to retain significant sodium-dependent uridine transport activity when expressed in oocytes.