Effect of antenatal micronutrient or antidepressant exposure on Brazelton neonatal behavioral assessment scale (NBAS) performance within one-month of birth

BACKGROUND

Antenatal depression is a risk factor for poor infant outcomes. Broad-spectrum-micronutrients (vitamins and minerals) have shown efficacy in treating psychiatric symptoms in non-pregnant populations and are associated with reduced incidence of adverse birth outcomes, and improvements in neonatal development. We investigated the effects of treatment of antenatal depression with micronutrients above the Recommended Dietary Allowance on infant development compared to treatment with antidepressant medications and controls.

METHOD

One-hundred-and-three infants were assessed using the Brazelton Neonatal Behavioral Assessment Scale (NBAS) within 28 days of birth: 37 exposed to micronutrients in-utero (50-182 days exposure), 18 to antidepressants in-utero (exposure for full gestation), and 48 controls whose mothers received neither treatment nor experienced depressive symptoms.

RESULTS

Controlling for gestational age and parity, there were significant group differences on habituation, orientation, motor, state regulation, autonomic stability and reflexes (p < .05). Micronutrient-exposed performed better than antidepressant-exposed and controls on habituation, motor and autonomic stability (p < .05), effect sizes ranged 1.0-1.7 and 0.5-1.0, respectively. Antidepressant-exposed performed significantly worse on orientation and reflexes compared to micronutrient-exposed and controls. Micronutrient-exposed had significantly better state regulation compared to antidepressant-exposed. There was an association between micronutrient exposure length and better habituation (r = 0.41, p = .028). Micronutrient exposure was generally identified as a stronger predictor of neonatal performance over maternal depression, social adversity, gestational age and infant sex.

CONCLUSION

In-utero micronutrient exposure appears to mitigate risks of depression on infant outcomes showing positive effects on infant behavior, on par with or better than typical pregnancies and superior to antidepressants. Limitations include differential exposure to micronutrients/antidepressants and lack of group blinding.

Very-Long-Chain Unsaturated Sphingolipids Mediate Oleate-Induced Rat β-Cell Proliferation

Fatty acid (FA) signaling contributes to β-cell mass expansion in response to nutrient excess, but the underlying mechanisms are poorly understood. In the presence of elevated glucose, FA metabolism is shifted toward synthesis of complex lipids, including sphingolipids. Here, we tested the hypothesis that sphingolipids are involved in the β-cell proliferative response to FA. Isolated rat islets were exposed to FA and 16.7 mmol/L glucose for 48-72 h, and the contribution of the de novo sphingolipid synthesis pathway was tested using the serine palmitoyltransferase inhibitor myriocin, the sphingosine kinase (SphK) inhibitor SKI II, or knockdown of SphK, fatty acid elongase 1 (ELOVL1) and acyl-CoA-binding protein (ACBP). Rats were infused with glucose and the lipid emulsion ClinOleic and received SKI II by gavage. β-Cell proliferation was assessed by immunochemistry or flow cytometry. Sphingolipids were analyzed by liquid chromatography-tandem mass spectrometry. Among the FAs tested, only oleate increased β-cell proliferation. Myriocin, SKI II, and SphK knockdown all decreased oleate-induced β-cell proliferation. Oleate exposure did not increase the total amount of sphingolipids but led to a specific rise in 24:1 species. Knockdown of ACBP or ELOVL1 inhibited oleate-induced β-cell proliferation. We conclude that unsaturated very-long-chain sphingolipids produced from the available C24:1 acyl-CoA pool mediate oleate-induced β-cell proliferation in rats.

14-3-3ζ constrains insulin secretion by regulating mitochondrial function in pancreatic β-cells

While critical for neurotransmitter synthesis, 14-3-3 proteins are often assumed to have redundant functions due to their ubiquitous expression, but despite this assumption, various 14-3-3 isoforms have been implicated in regulating metabolism. We previously reported contributions of 14-3-3ζ in β cell function, but these studies were performed in tumor-derived MIN6 cells and systemic KO mice. To further characterize the regulatory roles of 14-3-3ζ in β cell function, we generated β cell–specific 14-3-3ζ–KO mice. Although no effects on β cell mass were detected, potentiated glucose-stimulated insulin secretion (GSIS), mitochondrial function, and ATP synthesis were observed. Deletion of 14-3-3ζ also altered the β cell transcriptome, as genes associated with mitochondrial respiration and oxidative phosphorylation were upregulated. Acute 14-3-3 protein inhibition in mouse and human islets recapitulated the enhancements in GSIS and mitochondrial function, suggesting that 14-3-3ζ is the critical isoform in β cells. In dysfunctional db/db islets and human islets from type 2 diabetic donors, expression of Ywhaz/YWHAZ, the gene encoding 14-3-3ζ, was inversely associated with insulin secretion, and pan–14-3-3 protein inhibition led to enhanced GSIS and mitochondrial function. Taken together, this study demonstrates important regulatory functions of 14-3-3ζ in the regulation of β cell function and provides a deeper understanding of how insulin secretion is controlled in β cells.

Clinical utility of reflex testing with cancer biomarkers to improve diagnostic accuracy of primary Human Papillomavirus screening

BACKGROUND

HPV testing is the cornerstone of cervical cancer screening with outstanding sensitivity but only moderate specificity. We evaluated whether reflex testing for cancer biomarkers improves the sensitivity/specificity balance of screening.

METHODS

Cervical samples from women in Cape Town, South Africa, aged 30-65 years, were collected and tested with Xpert HPV and with real-time PCR to detect mRNA for Cyclin-Dependent Kinase Inhibitor 2A (CDKN2A), Topoisomerase 2 alpha (TOP2A) and Ki67 (MKi67). Women with histologically-confirmed cervical intraepithelial neoplasia grade 2 or worse (CIN2+) (85 women without and 166 with HIV) and women with no cervical disease (331 without and 257 with HIV) were included.

RESULTS

When used as reflex tests after a positive HPV result, biomarkers discriminated well between women with and without CIN2+. The inclusion of both CDKN2A and MKi67 had the best performance with area under the curve (AUC) of 0.9171 and 0.8734 in women without and with HIV, respectively. While excellent, these performance parameters did not improve on an approach utilizing only HPV testing with more stringent cycle threshold cut-offs and HPV genotype selection which achieved AUC of 0.9059 and 0.8705 in women without and with HIV, respectively.

CONCLUSION

Biomarkers can be used as triage after positive HPV results but do not out-perform an approach utilizing higher viral load cut-offs on selected high-risk genotypes.

IMPACT

A screening approach using HPV testing alone can be more easily implemented at the point-of-care.

The Tetracycline-Controlled Transactivator (Tet-On/Off) System in β-Cells Reduces Insulin Expression and Secretion in Mice

Controllable genetic manipulation is an indispensable tool in research, greatly advancing our understanding of cell biology and physiology. However in β-cells, transgene silencing, low inducibility, ectopic expression, and off-targets effects are persistent challenges. In this study, we investigated whether an inducible Tetracycline (Tet)-Off system with β-cell-specific mouse insulin promoter (MIP)-itTA-driven expression of tetracycline operon (TetO)-Cre^Jaw/J could circumvent previous issues of specificity and efficacy. Following assessment of tissue-specific gene recombination, β-cell architecture, in vitro and in vivo glucose-stimulated insulin secretion, and whole-body glucose homeostasis, we discovered that expression of any tetracycline-controlled transactivator (e.g., improved itTA, reverse rtTA, or tTA) in β-cells significantly reduced Insulin gene expression and decreased insulin content. This translated into lower pancreatic insulin levels and reduced insulin secretion in mice carrying any tTA transgene, independent of Cre recombinase expression or doxycycline exposure. Our study echoes ongoing challenges faced by fundamental researchers working with β-cells and highlights the need for consistent and comprehensive controls when using the tetracycline-controlled transactivator systems (Tet-On or Tet-Off) for genome editing.

Evidence for the existence and potential roles of intra-islet glucagon-like peptide-1

Glucagon-Like Peptide-1 (GLP-1) is an important peptide hormone secreted by L-cells in the gastrointestinal tract in response to nutrients. It is produced by the differential cleavage of the proglucagon peptide. GLP-1 elicits a wide variety of physiological responses in many tissues that contribute to metabolic homeostasis. For these reasons, therapies designed to either increase endogenous GLP-1 levels or introduce exogenous peptide mimetics are now widely used in the management of diabetes. In addition to GLP-1 production from L-cells, recent reports suggest that pancreatic islet alpha cells may also synthesize and secrete GLP-1. Intra-islet GLP-1 may therefore play an unappreciated role in islet health and glucose regulation, suggesting a potential functional paracrine role for islet-derived GLP-1. In this review, we assess the current literature from an islet-centric point-of-view to better understand the production, degradation, and actions of GLP-1 within the endocrine pancreas in rodents and humans. The relevance of intra-islet GLP-1 in human physiology is discussed regarding the potential role of intra-islet GLP-1 in islet health and dysfunction.

Combined Deletion of Free Fatty-Acid Receptors 1 and 4 Minimally Impacts Glucose Homeostasis in Mice

The free fatty-acid receptors FFAR1 (GPR40) and FFAR4 (GPR120) are implicated in the regulation of insulin secretion and insulin sensitivity, respectively. Although GPR120 and GPR40 share similar ligands, few studies have addressed possible interactions between these 2 receptors in the control of glucose homeostasis. Here we generated mice deficient in gpr120 (Gpr120KO) or gpr40 (Gpr40KO), alone or in combination (Gpr120/40KO), and metabolically phenotyped male and female mice fed a normal chow or high-fat diet. We assessed insulin secretion in isolated mouse islets exposed to selective GPR120 and GPR40 agonists singly or in combination. Following normal chow feeding, body weight and energy intake were unaffected by deletion of either receptor, although fat mass increased in Gpr120KO females. Fasting blood glucose levels were mildly increased in Gpr120/40KO mice and in a sex-dependent manner in Gpr120KO and Gpr40KO animals. Oral glucose tolerance was slightly reduced in male Gpr120/40KO mice and in Gpr120KO females, whereas insulin secretion and insulin sensitivity were unaffected. In hyperglycemic clamps, the glucose infusion rate was lower in male Gpr120/40KO mice, but insulin and c-peptide levels were unaffected. No changes in glucose tolerance were observed in either single or double knock-out animals under high-fat feeding. In isolated islets from wild-type mice, the combination of selective GPR120 and GPR40 agonists additively increased insulin secretion. We conclude that while simultaneous activation of GPR120 and GPR40 enhances insulin secretion ex vivo, combined deletion of these 2 receptors only minimally affects glucose homeostasis in vivo in mice.

Free fatty acid receptor 4 inhibitory signaling in delta cells regulates islet hormone secretion in mice

OBJECTIVE

Maintenance of glucose homeostasis requires the precise regulation of hormone secretion from the endocrine pancreas. Free fatty acid receptor 4 (FFAR4/GPR120) is a G protein-coupled receptor whose activation in islets of Langerhans promotes insulin and glucagon secretion and inhibits somatostatin secretion. However, the contribution of individual islet cell types (α, β, and δ cells) to the insulinotropic and glucagonotropic effects of GPR120 remains unclear. As gpr120 mRNA is enriched in somatostatin-secreting δ cells, we hypothesized that GPR120 activation stimulates insulin and glucagon secretion via inhibition of somatostatin release.

METHODS

Glucose tolerance tests were performed in mice after administration of selective GPR120 agonist Compound A. Insulin, glucagon, and somatostatin secretion were measured in static incubations of isolated mouse islets in response to endogenous (ω-3 polyunsaturated fatty acids) and/or pharmacological (Compound A and AZ-13581837) GPR120 agonists. The effect of Compound A on hormone secretion was tested further in islets isolated from mice with global or somatostatin cell-specific knock-out of gpr120. Gpr120 expression was assessed in pancreatic sections by RNA in situ hybridization. Cyclic AMP (cAMP) and calcium dynamics in response to pharmacological GPR120 agonists were measured specifically in α, β, and δ cells in intact islets using cAMPER and GCaMP6 reporter mice, respectively.

RESULTS

Acute exposure to Compound A increased glucose tolerance, circulating insulin, and glucagon levels in vivo. Endogenous and/or pharmacological GPR120 agonists reduced somatostatin secretion in isolated islets and concomitantly demonstrated dose-dependent potentiation of glucose-stimulated insulin secretion and arginine-stimulated glucagon secretion. Gpr120 was enriched in δ cells. Pharmacological GPR120 agonists reduced cAMP and calcium levels in δ cells but increased these signals in α and β cells. Compound A-mediated inhibition of somatostatin secretion was insensitive to pertussis toxin. The effect of Compound A on hormone secretion was completely absent in islets from mice with either global or somatostatin cell-specific deletion of gpr120 and partially reduced upon blockade of somatostatin receptor signaling by cyclosomatostatin.

CONCLUSIONS

Inhibitory GPR120 signaling in δ cells contributes to both insulin and glucagon secretion in part by mitigating somatostatin release.

Vitamin D is an endogenous partial agonist of the transient receptor potential vanilloid 1 channel

KEY POINTS

25-Hydroxyvitamin D (25OHD) is a partial agonist of TRPV1 whereby 25OHD can weakly activate TRPV1 yet antagonize the stimulatory effects of the full TRPV1 agonists capsaicin and oleoyl dopamine. 25OHD binds to TRPV1 within the same vanilloid binding pocket as capsaicin. 25OHD inhibits the potentiating effects of PKC-mediated TRPV1 activity. 25OHD reduces T-cell activation and trigeminal neuron calcium signalling mediated by TRPV1 activity. These results provide evidence that TRPV1 is a novel receptor for the biological actions of vitamin D in addition to the well-documented effects of vitamin D upon the nuclear vitamin D receptor. The results may have important implications for our current understanding of certain diseases where TRPV1 and vitamin D deficiency have been implicated, such as chronic pain and autoimmune diseases, such as type 1 diabetes.

ABSTRACT

The capsaicin receptor TRPV1 plays an important role in nociception, inflammation and immunity and its activity is regulated by exogenous and endogenous lipophilic ligands. As vitamin D is lipophilic and involved in similar biological processes as TRPV1, we hypothesized that it directly regulates TRPV1 activity and function. Our calcium imaging and electrophysiological data demonstrate that vitamin D (25-hydroxyvitamin D (25OHD) and 1,25-hydroxyvitamin D (1,25OHD)) can weakly activate TRPV1 at physiologically relevant concentrations (100 nM). Furthermore, both 25OHD and 1,25OHD can inhibit capsaicin-induced TRPV1 activity (IC50  = 34.3 ± 0.2 and 11.5 ± 0.9 nM, respectively), but not pH-induced TRPV1 activity, suggesting that vitamin D interacts with TRPV1 in the same region as the TRPV1 agonist capsaicin. This hypothesis is supported by our in silico TRPV1 structural modelling studies, which place 25OHD in the same binding region as capsaicin. 25OHD also attenuates PKC-dependent TRPV1 potentiation via interactions with a known PKC phospho-acceptor residue in TRPV1. To provide evidence for a physiological role for the interaction of vitamin D with TRPV1, we employed two different cellular models known to express TRPV1: mouse CD4+ T-cells and trigeminal neurons. Our results indicate that 25OHD reduces TRPV1-induced cytokine release from T-cells and capsaicin-induced calcium activity in trigeminal neurons. In summary, we provide evidence that vitamin D is a novel endogenous regulator of TRPV1 channel activity that may play an important physiological role in addition to its known effects through the canonical nuclear vitamin D receptor pathway.

Costarting sitagliptin with metformin is associated with a lower likelihood of disease progression in newly treated people with type 2 diabetes: a cohort study

AIM

To examine whether early addition of sitagliptin to metformin is associated with a delay in type 2 diabetes progression.

METHODS

Administrative health records from Alberta, Canada, for the period April 2008 to March 2015, were used to conduct a retrospective cohort study in new metformin users. People who started sitagliptin on the same day they initiated metformin therapy were compared with those who added sitagliptin later. Insulin initiation served as a surrogate marker for diabetes progression, and multivariable logistic regression models were used to evaluate the association with sitagliptin addition (costart vs later use). A mixed-effects linear regression model was used to examine the effect of timing of sitagliptin addition on HbA_1c change over 1 year.

RESULTS

The mean (sd) age of the 8764 people who used sitagliptin was 52.1 (11.1) years, 5665 (64.6%) were men, and 1153 (13.2%) started sitagliptin on the same day as metformin. Insulin was added to the therapy of 173 (15.0%) costarters and 1453 (19.1%) later sitagliptin users. The adjusted odds ratio for adding insulin was 0.76 (95% CI 0.64 to 0.90) in favour of costarting sitagliptin. HbA_1c levels decreased in both groups 1 year after starting sitagliptin, with costarters having a significantly greater reduction [absolute between-group difference of 0.5% (95% CI 0.3 to 0.7)] compared with later sitagliptin users.

CONCLUSION

Costarting drug therapy with sitagliptin and metformin was associated with a lower likelihood of disease progression in people with type 2 diabetes compared with adding sitagliptin later.

Validation of an mRNA-based Urine Test for the Detection of Bladder Cancer in Patients with Haematuria

BACKGROUND

In patients with haematuria, a fast, noninvasive test with high sensitivity (SN) and negative predictive value (NPV), which is able to detect or exclude bladder cancer (BC), is needed. A newly developed urine assay, Xpert Bladder Cancer Detection (Xpert), measures five mRNA targets (ABL1, CRH, IGF2, UPK1B, and ANXA10) that are frequently overexpressed in BC.

OBJECTIVE

To validate the performance of Xpert in patients with haematuria.

DESIGN, SETTING, AND PARTICIPANTS

Voided precystoscopy urine specimens were prospectively collected at 22 sites from patients without prior BC undergoing cystoscopy for haematuria. Xpert, cytology, and UroVysion procedures were performed. Technical validation was performed and specificity (SP) was determined in patients without BC.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Test characteristics were calculated based on cystoscopy and histology results, and compared between Xpert, cytology, and UroVysion.

RESULTS AND LIMITATIONS

We included 828 patients (mean age 64.5 yr, 467 males, 401 never smoked). Xpert had an SN of 78% (95% confidence interval [CI]: 66-87) overall and 90% (95% CI: 76-96) for high-grade (HG) tumours. The NPV was 98% (95% CI: 97-99) overall. The SP was 84% (95% CI: 81-86). In patients with microhaematuria, only one HG patient was missed (NPV 99%). Xpert had higher SN and NPV than cytology and UroVysion. Cytology had the highest SP (97%). In a separate SP study, Xpert had an SP of 89% in patients with benign prostate hypertrophy and 92% in prostate cancer patients.

CONCLUSIONS

Xpert is an easy-to-use, noninvasive test with improved SN and NPV compared with cytology and UroVysion, representing a promising tool for identifying haematuric patients with a low likelihood of BC who might not need to undergo cystoscopy.

PATIENT SUMMARY

Xpert is an easy-to-perform urine test with good performance compared with standard urine tests. It should help identify (micro)haematuria patients with a very low likelihood to have bladder cancer.

Human islets contain a subpopulation of glucagon-like peptide-1 secreting α cells that is increased in type 2 diabetes

Objectives

Our study shows that glucagon-like peptide-1 (GLP-1) is secreted within human islets and may play an unexpectedly important paracrine role in islet physiology and pathophysiology. It is known that α cells within rodent and human pancreatic islets are capable of secreting GLP-1, but little is known about the functional role that islet-derived GLP-1 plays in human islets.

Methods

We used flow cytometry, immunohistochemistry, perifusions, and calcium imaging techniques to analyse GLP-1 expression and function in islets isolated from cadaveric human donors with or without type 2 diabetes. We also used immunohistochemistry to analyse GLP-1 expression within islets from pancreatic biopsies obtained from living donors.

Results

We have demonstrated that human islets secrete ∼50-fold more GLP-1 than murine islets and that ∼40% of the total human α cells contain GLP-1. Our results also confirm that dipeptidyl peptidase-4 (DPP4) is expressed in α cells. Sitagliptin increased GLP-1 secretion from cultured human islets but did not enhance glucose-stimulated insulin secretion (GSIS) in islets from non-diabetic (ND) or type 2 diabetic (T2D) donors, suggesting that β cell GLP-1 receptors (GLP-1R) may already be maximally activated. Therefore, we tested the effects of exendin-9, a GLP-1R antagonist. Exendin-9 was shown to reduce GSIS by 39% and 61% in ND islets and T2D islets, respectively. We also observed significantly more GLP-1+ α cells in T2D islets compared with ND islets obtained from cadaveric donors. Furthermore, GLP-1+ α cells were also identified in pancreatic islet sections obtained from living donors undergoing surgery.

Conclusions

In summary, we demonstrated that human islets secrete robust amounts of GLP-1 from an α cell subpopulation and that GLP-1R signalling may support GSIS to a greater extent in T2D islets.

•

Here we show that glucagon-like peptide-1 (GLP-1) is secreted from a subpopulation of α cells within human islets.

•

Human islets secrete ∼50-fold more GLP-1 than murine islets and that ∼40% of the total human α cells contain GLP-1.

•

We observed significantly more GLP-1+ α cells in islets from donors with type 2 diabetes than in islets from donors with no diabetes.

•

GLP-1+ α cells can also be detected in pancreatic islet sections obtained from living donors undergoing surgery.

•

GLP-1 receptor signaling may support insulin secretion to a greater extent in type 2 diabetes.

The antianginal ranolazine mitigates obesity-induced nonalcoholic fatty liver disease and increases hepatic pyruvate dehydrogenase activity

Obese individuals are often at risk for nonalcoholic fatty liver disease (NAFLD), insulin resistance, type 2 diabetes (T2D), and cardiovascular diseases such as angina, thereby requiring combination therapies for their comorbidities. Ranolazine is a second-line antianginal agent that also improves glycemia, and our aim was to determine whether ranolazine modifies the progression of obesity-induced NAFLD. Twelve-week-old C57BL/6J male mice were fed a low-fat or high-fat diet for 10 weeks and then treated for 30 days with either vehicle control or ranolazine (50 mg/kg via daily s.c. injection). Glycemia was monitored via glucose/pyruvate/insulin tolerance testing, whereas in vivo metabolism was assessed via indirect calorimetry. Hepatic triacylglycerol content was quantified via the Bligh and Dyer method. Consistent with previous reports, ranolazine treatment reversed obesity-induced glucose intolerance, which was associated with reduced body weight and hepatic steatosis, as well as increased hepatic pyruvate dehydrogenase (PDH) activity. Ranolazine's actions on hepatic PDH activity may be directly mediated, as ranolazine treatment reduced PDH phosphorylation (indicative of increased PDH activity) in HepG2 cells. Therefore, in addition to mitigating angina, ranolazine also reverses NAFLD, which may contribute to its documented glucose-lowering actions, situating ranolazine as an ideal antianginal therapy for obese patients comorbid for NAFLD and T2D.

Prospective Validation of an mRNA-based Urine Test for Surveillance of Patients with Bladder Cancer

BACKGROUND

A fast, noninvasive test with high sensitivity (SN) and a negative predictive value (NPV), which is able to detect recurrences in bladder cancer (BC) patients, is needed. A newly developed urine assay, Xpert Bladder Cancer Monitor (Xpert), measures five mRNA targets (ABL1, CRH, IGF2, UPK1B, and ANXA10) that are frequently overexpressed in BC.

OBJECTIVE

To validate Xpert characteristics in patients previously diagnosed with non-muscle-invasive BC.

DESIGN, SETTING, AND PARTICIPANTS

Voided precystoscopy urine samples were prospectively collected at 22 sites. Xpert, cytology, and UroVysion were performed. If cystoscopy was suspicious for BC, a histologic examination was performed. Additionally, technical validation was performed and specificity was determined in patients without a history or clinical evidence of BC.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Test characteristics were calculated based on cystoscopy and histology results, and compared between Xpert, cytology, and UroVysion.

RESULTS AND LIMITATIONS

Of the eligible patients, 239 with a history of BC had results for all assays. The mean age was 71 yr; 190 patients were male, 53 never smoked, and 64% had previous intravesical immunotherapy (35%) or chemotherapy (29%). Forty-three cases of recurrences occurred. Xpert had overall SN of 74% (95% confidence interval [CI]: 60-85) and 83% (95% CI: 64-93) for high-grade (HG) tumors. The NPV was 93% (95% CI: 89-96) overall and 98% (95% CI: 94-99) for HG tumors. Specificity was 80% (95% CI: 73-85). Xpert SN and NPV were superior to those of cytology and UroVysion. Specificity in non-BC individuals (n=508) was 95% (95% CI: 93-97).

CONCLUSIONS

Xpert has an improved NPV compared with UroVysion and cytology in patients under follow-up for BC. It represents a promising tool for excluding BC in these patients, reducing the need for cystoscopy.

PATIENT SUMMARY

Xpert is an easy-to-perform urine test with good performance compared with standard urine tests. It should help optimize the follow-up of recurrent bladder cancer patients.

Variable range hopping conduction in ZnO nanocrystal thin films

Zinc oxide (ZnO) nanocrystal films are of interest for new applications in thin film transistors and as transparent conductive oxides. Previous work has concentrated on achieving highly conductive, metallic films. This work focusses on the less explored insulating to semi-insulating regime, which enables obtaining deeper insights into the roles of surface states and defect states trapped at the nanocrystal interfaces. We examine the effects of various post-deposition treatments including controlled dosing with ultraviolet light, filling the voids between nanocrystals with a matrix material deposited by atomic layer deposition, and thermal annealing of the nanocrystal films. Both Mott and Efros-Shklovskii variable range hopping are observed depending on the carrier concentration in the nanocrystals. Using the above post-treatments to transition the films between the two conduction mechanisms enables determining the Fermi level density of states and the electron localization length. To interpret our results, we propose a model based on the assumption of nanocrystals consisting of quasi-neutral cores surrounded by shells depleted by surface OH trap states. The model suggests that the primary source of the increased conductivity in ZnO nanocrystal films based on post-treatments is an increase in the ability to tunnel between nanocrystals due to a reduction of the distance between the quasi-neutral nanocrystal cores.

Environmental photostability of SF6-etched silicon nanocrystals

We report on the long-term environmental stability of the photoluminescent (PL) properties of silicon nanocrystals (SiNCs). We prepared sulfur hexafluoride (SF(6)) etched SiNCs in a two-stage plasma reactor and investigated their PL stability against UV irradiation in air. Unlike SiNCs with hydrogen-passivated surfaces, the SF(6)-etched SiNCs exhibit no photobleaching upon extended UV irradiation despite surface oxidation. Furthermore, the PL quantum yield also remains stable upon heating the SF(6)-etched SiNCs up to 160 °C. The observed thermal and UV stability of SF(6)-etched SiNCs combined with their PL quantum yields of up to ~50% make them attractive candidates for UV downshifting to enhance the efficiency of solar cells. Electron paramagnetic spin resonance indicates that the SF(6)-etched SiNCs have a lowered density of defect states, both as-formed and after room temperature oxidation in air.

Comparative assessment of a DNA and protein Leishmania donovani gamma glutamyl cysteine synthetase vaccine to cross-protect against murine cutaneous leishmaniasis caused by L. major or L. mexicana infection

Leishmaniasis is a major health problem and it is estimated that 12 million people are currently infected. A vaccine which could cross-protect people against different Leishmania spp. would facilitate control of this disease as more than one species of Leishmania may be present. In this study the ability of a DNA vaccine, using the full gene sequence for L. donovani gamma glutamyl cysteine synthetase (γGCS) incorporated in the pVAX vector (pVAXγGCS), and a protein vaccine, using the corresponding recombinant L. donovani γGCS protein (LdγGCS), to protect against L. major or L. mexicana infection was evaluated. DNA vaccination gave transient protection against L. major and no protection against L. mexicana despite significantly enhancing specific antibody titres in vaccinated infected mice compared to infected controls. Vaccination with the LdγGCS protected against both species but only if the protein was incorporated into non-ionic surfactant vesicles for L. mexicana. The results of this study indicate that a L. donovani γGCS vaccine could be used to vaccinate against more than one Leishmania species but only if the recombinant protein is used.

Vaccination with recombinant Leishmania donovani gamma-glutamylcysteine synthetase fusion protein protects against L. donovani infection

Visceral leishmaniasis presents a serious health threat in many parts of the world. There is, therefore, an urgent need for an approved vaccine for clinical use to protect against infection. In this study, the ability of recombinant Leishmania donovani gamma-glutamyl cysteine synthetase protein (LdγGCS) alone or incorporated into a non-ionic surfactant vesicle (NIV) delivery system to protect against L. donovani infection was evaluated in a BALB/c mouse model. Immunization with LdγGCS alone or LdγGCS-NIV induced specific IgG1 and IgG2a antibodies compared to controls, with LdγGCS-NIV inducing significantly higher titers of both antibody classes (P < 0.05). Both formulations induced similar increases in splenocyte IFN-γ production following ex vivo antigen stimulation with LdγGCS compared with cells from control mice (P < 0.05). Similar levels of protection against infection were induced by LdγGCS alone and LdγGCS-NIV, based on their ability to suppress liver parasite burdens compared to control values (P < 0.01), indicating that using a carrier system did not enhance the protective responses induced by the recombinant protein. The results of this study indicate that LdγGCS may be a useful component in a vaccine against L. donovani.

SF6 plasma etching of silicon nanocrystals

An SF(6)-based plasma has been employed to perform in-flight etching of silicon nanocrystals (Si-NCs) after they were synthesized in an SiH(4)-based plasma. The photoluminescence of the Si-NCs blue-shifts after etching, indicating an etching-induced size reduction of the Si-NCs. It is shown that both the SF(6) plasma power and the flow rate can be utilized to control the etch rate (and thus the size reduction) of the Si-NCs. The SF(6) etched Si-NCs show only low concentrations of residual impurities other than fluorine. Quantum yields as high as 50% have been observed from these SF(6) etched Si-NCs despite oxidation.

Air-stable full-visible-spectrum emission from silicon nanocrystals synthesized by an all-gas-phase plasma approach

A novel dual-plasma system has been developed to combine the synthesis of silicon nanocrystals (Si-NCs), the etching to controllably tailor the Si-NC size, and the surface functionalization of Si-NCs into one simple all-gas-phase process. Si-NCs are synthesized in SiH(4)-based plasma; they then travel through CF(4)-based plasma, where Si-NCs are etched and passivated by C and F. The resulting Si-NCs exhibit air-stable emission across the full visible spectrum. Structural and optical characterization indicates that the emission in the red-to-green range is based on the recombination of quantum-confined excitons in Si-NCs, while the blue emission originates from defect states. The quantum yields of stabilized photoluminescence from Si-NCs range from 16% at the red end to 1% at the blue end.

Characterizing potential exposure to the public from low-level radioactive waste transportation by truck

To address public concern about potential exposure to gamma radiation from legal-weight low-level radioactive waste truck shipments to the Nevada Test Site, a stationary, automated array of four pressurized ion chambers was established for trucks to pass through. Data were collected from 1,012 of the 2,260 trucks that transported low-level radioactive waste to the Nevada Test Site from February through December 2003. To avoid perception of biasing a potential exposure low, the maximum reading (muR per hour; muR h(-1)) from the array was assigned as the gross measurement value for each truck. [In this article, exposure measurements are reported as Roentgen (R), as this unit is consistent with the data readings of the measurement instruments and has been historically presented to public stakeholders. Subsequently, dose measurements are reported as Roentgen Equivalent Man (rem).] To calculate the "net exposure" for each truck, the average and standard deviation of the maximum background values during the corresponding 12-h period when the truck arrived were subtracted from the gross value. For 483 trucks (47.7%), calculated net exposure values were equal to or less than zero, indicating that the exposure from the truck was indistinguishable from background. An additional 206 trucks (20.4%) had calculated net exposure values ranging between 0.0 and 1.0 muR h(-1). Cumulative exposure scenarios appropriate for rural transportation routes to the Nevada Test Site were developed; however, these scenarios assumed the unlikely case that the same individual was exposed to all of the trucks on that route. Cumulative exposure values were dominated by a small percentage of the trucks with comparatively high values. In communities along transportation routes, the probability of an individual receiving a potential exposure from a single truck may be a more meaningful perspective.

Natural history and surgical treatment of brown tumor lesions at various sites in refractory primary hyperparathyroidism

OBJECTIVE

Nowadays, the occurrence of brown tumor lesions or osteitis fibrosa cystica caused by long-lasting primary hyperparathyroidism are very rare, since measuring serum calcium became available routinely in the mid-1970s. It is a tumor-like lesion that may affect the entire skeleton, often presenting with diffuse focal bone pain or by pathological fracture.

METHODS

We describe our experience of brown tumor lesions at different skeletal sites that were treated at our trauma centre within the last two years. This included surgical therapy for the indications (i) pain at the pelvis, (ii) increased risk for pathological fracture at the tibia and (iii) acute radicular symptoms at the lumbar spine. The literature was reviewed for the current understanding of the pathophysiology as well as therapy of brown tumor lesions in primary hyperparathyroidism.

RESULTS

Curettage of a left-sided iliac crest brown tumor terminated focal pain. A less invasive stabilisation system and bone cement decreased both patient pain and the fracture risk of brown tumor lesion sites of the shinbone; and internal fixator including laminectomy at the lumbar spine ended radicular symptoms.

CONCLUSION

Patients with refractory primary hyperparathyroidism should be monitored closely by endocrinologists and the patient's serum calcium level should be adjusted as far as possible. Radiography is required only if focal bone pain or pathological fractures or radicular symptoms occur. Surgery should be considered if large bone defects with spontaneous fracture risk or increasing pain are present. Tumor curettage, Palacos plombage and less invasive stabilisation systems have proved to be acceptable surgical options.

Enzymes of type II fatty acid synthesis and apicoplast differentiation and division in Eimeria tenella

Apicomplexan parasites, Eimeria tenella, Plasmodium spp. and Toxoplasma gondii, possess a homologous plastid-like organelle termed the apicoplast, derived from the endosymbiotic enslavement of a photosynthetic alga. However, currently no eimerian nuclear encoded apicoplast targeted proteins have been identified, unlike in Plasmodium spp. and T. gondii. In this study, we demonstrate that nuclear encoded enoyl reductase of E. tenella (EtENR) has a predicted N-terminal bipartite transit sequence, typical of apicoplast-targeted proteins. Using a combination of immunocytochemistry and EM we demonstrate that this fatty acid biosynthesis protein is located in the apicoplast of E. tenella. Using the EtENR as a tool to mark apicoplast development during the Eimeria lifecycle, we demonstrate that nuclear and apicoplast division appear to be independent events, both organelles dividing prior to daughter cell formation, with each daughter cell possessing one to four apicoplasts. We believe this is the first report of multiple apicoplasts present in the infectious stage of an apicomplexan parasite. Furthermore, the microgametes lacked an identifiable apicoplast consistent with maternal inheritance via the macrogamete. It was found that the size of the organelle and the abundance of EtENR varied with developmental stage of the E. tenella lifecycle. The high levels of EtENR protein observed during asexual development and macrogametogony is potentially associated with the increased synthesis of fatty acids required for the rapid formation of numerous merozoites and for the extracellular development and survival of the oocyst. Taken together the data demonstrate that the E. tenella apicoplast participates in type II fatty acid biosynthesis with increased expression of ENR during parasite growth. Apicoplast division results in the simultaneous formation of multiple fragments. The division mechanism is unknown, but is independent of nuclear division and occurs prior to daughter formation.

A Methodology for Investigating New Nonprecious Metal Catalysts for PEM Fuel Cells

This paper reports an approach to investigate metal-chalcogen materials as catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells. The methodology is illustrated with reference to Co-Se thin films prepared by magnetron sputtering onto a glassy-carbon substrate. Scanning Auger microscopy (SAM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) have been used, in parallel with electrochemical activity and stability measurements, to assess how the electrochemical performance relates to chemical composition. It is shown that Co-Se thin films with varying Se are active for oxygen reduction, although the open circuit potential (OCP) is lower than for Pt. A kinetically controlled process is observed in the potential range 0.5-0.7 V (vs reversible hydrogen electrode) for the thin-film catalysts studied. An initial exposure of the thin-film samples to an acid environment served as a pretreatment, which modified surface composition prior to activity measurements with the rotating disk electrode (RDE) method. Based on the SAM characterization before and after electrochemical tests, all surfaces demonstrating activity are dominated by chalcogen. XRD shows that the thin films have nanocrystalline character that is based on a Co(1-x)Se phase. Parallel studies on Co-Se powder supported on XC72R carbon show comparable OCP, Tafel region, and structural phase as for the thin-film model catalysts. A comparison for ORR activity has also been made between this Co-Se powder and a commercial Pt catalyst.

Two-cell to N-cell heterogeneous, inhibitory networks: precise linking of multistable and coherent properties

Inhibitory networks are now recognized as being the controllers of several brain rhythms. However, experimental work with inhibitory cells is technically difficult not only because of their smaller percentage of the neuronal population, but also because of their diverse properties. As such, inhibitory network models with tight links to the experimental data are needed to understand their contributions to population rhythms. However, mathematical analyses of network models with more than two cells is challenging when the cellular models involve biophysical details. We use bifurcation analyses and simulations to show that two-cell analyses can quantitatively predict N-cell (N = 20, 50, 100) network dynamics for heterogeneous, inhibitory networks. Interestingly, multistable states in the two-cell system are manifest as different and distinct coherent network patterns in the N-cell networks for the same parameter sets.

Using heterogeneity to predict inhibitory network model characteristics

From modeling studies it has been known for >10 years that purely inhibitory networks can produce synchronous output given appropriate balances of intrinsic and synaptic parameters. Several experimental studies indicate that synchronous activity produced by inhibitory networks is critical to the production of population rhythms associated with various behavioral states. Heterogeneity of inputs to inhibitory networks strongly affect their ability to synchronize. In this paper, we explore how the amount of input heterogeneity to two-cell inhibitory networks affects their dynamics. Using numerical simulations and bifurcation analyses, we find that the ability of inhibitory networks to synchronize in the face of heterogeneity depends nonmonotonically on each of the synaptic time constant, synaptic conductance and external drive parameters. Because of this, an optimal set of parameters for a given cellular model with various biophysical characteristics can be determined. We suggest that this could be a helpful approach to use in determining the importance of different, underlying biophysical details. We further find that two-cell coherence properties are maintained in larger 10-cell networks. As such, we think that a strategy of "embedding" small network dynamics in larger networks is a useful way to understand the contribution of biophysically derived parameters to population dynamics in large networks.

A complete shikimate pathway in Toxoplasma gondii: an ancient eukaryotic innovation

The shikimate pathway is essential for survival of the apicomplexan parasites Plasmodium falciparum, Toxoplasma gondii and Cryptosporidium parvum. As it is absent in mammals it is a promising therapeutic target. Herein, we describe the genes encoding the shikimate pathway enzymes in T. gondii. The molecular arrangement and phylogeny of the proteins suggests homology with the eukaryotic fungal enzymes, including a pentafunctional AROM. Current rooting of the eukaryotic evolutionary tree infers that the fungi and apicomplexan lineages diverged deeply, suggesting that the arom is an ancient supergene present in early eukaryotes and subsequently lost or replaced in a number of lineages.

An acute hemolytic transfusion reaction due to anti-IH in a patient with sickle cell disease

BACKGROUND

A hemolytic transfusion reaction (HTR) due to anti-IH is reported in a patient with sickle cell disease (SCD).

CASE REPORT

An 18-year-old woman with SCD and a complete phenotype on file had been identified as group B-positive with negative antibody-screening tests and had received 1 unit of packed RBCs. Ten days later, she was readmitted in painful crisis with a Hb of 4.2 g per dL. Antibody-screening tests and panel cells were positive at all test phases with a negative autocontrol, which suggested alloantibodies. Phenotypically matched group O RBCs were issued emergently. After the transfusion of 100 mL, the patient had an HTR with chills, fever, and tachycardia and laboratory findings of hemoglobinemia, hemoglobinuria, and negative DATs. A high-titer, IgM anti-IH with a high thermal amplitude (reactive with group O, but not group B RBCs at 37 degrees C) was identified. Autologous RBCs appeared to have normal I antigen expression, but less H antigen than pooled group B RBCs. She was given group B RBCs, uneventfully, by use of a blood warmer.

CONCLUSIONS

This is a rare case of anti-IH as the cause of a HTR, as a serologic problem that may be seen in SCD, and as an autoantibody that may mimic an alloantibody. Ironically, this HTR resulted from the effort to provide phenotypically matched RBCs, which necessitated the selection of group O RBCs.

Crystallization and preliminary X-ray analysis of shikimate dehydrogenase from Escherichia coli

Shikimate dehydrogenase from Escherichia coli has been crystallized by the vapour-diffusion method using ammonium sulfate as a precipitant. Mass spectrometry confirmed the purity of the enzyme and dynamic light scattering was used to find the appropriate additives to yield a monodisperse enzyme solution. The crystals are monoclinic, space group C2, with unit-cell parameters a = 110.0, b = 139.8, c = 102.6 A, beta = 122.2 degrees (at 100 K). Native crystals diffract to 2.3 A in-house on a rotating-anode X-ray source. The asymmetric unit is likely to contain four molecules, related by 222 symmetry, corresponding to a packing density of 2.86 A(3) Da(-1).

Characterization of P1,P4-diadenosine 5'-tetraphosphate binding on bovine aortic endothelial cells

In recent years it has become increasingly clear that alpha, omega-dinucleotides act as extracellular modulators of various biological processes. P1,P4-diadenosine 5'-tetraphosphate (Ap4A) is the best characterized alpha,omega-dinucleotides and acts as an extracellular signal molecule by inducing the release of nitric oxide (NO) from bovine aortic endothelial cells (BAEC) (R. H. Hilderman, and E. F. Christensen (1998) FEBS Lett. 407, 320-324). However, the characteristics of Ap4A binding to endothelial cells have not been determined. In this report we demonstrate that Ap4A binds to a heterogeneous population of receptors on BAEC. Competition ligand-binding studies using various adenosine dinucleotides, guanosine dinucleotides, adenosine/guanosine dinucleotides, and synthetic P2 purinoceptor agonists and antagonists demonstrate that Ap4A binds to a receptor on BAEC that has a high affinity for some of the adenosine dinucleotides. The apparent IC50 values for Ap4A, Ap2A, and Ap3A are between 12 and 15 microM, while the apparent IC50 values for Ap5A and Ap6A are greater than 500 microM. Evidence is also presented which suggests that this receptor can be classified as a putative P4 purinoceptor. Competition studies also demonstrate that Ap4A binds at a lower affinity to a second class of binding sites.

Synergistic effects of feeding and dexamethasone on serum leptin levels

The objectives of this study were to determine the time course of the stimulatory effect of dexamethasone on serum leptin and whether it depends on food intake. Dexamethasone (4mg) was administered I.V. over 1 minute to healthy human volunteers (n=8) under fasting and feeding conditions (2000 kcal given at three meals over 7 hours). At 10 hours, serum leptin levels were increased only in the fed subjects (delta leptin 10.6+/-1.6 vs -2.4+/-1.9 ng/ml, p=0.01, n=8). To assess the interactive effect of food and dexamethasone on serum leptin, a subgroup (n=4) was studied under 4 conditions: 1) dexamethasone/fast; 2) dexamethasone/food; 3) saline/fast; 4) saline/food. Serum leptin declined from baseline under the fasting conditions, with or without dexamethasone. Feeding prevented the drop in serum leptin. In the dexamethasone/food condition, leptin levels rose from baseline after 7 hours and doubled after 10 hours (p<0.05). The rise in serum leptin was significantly greater in the food/dexamethasone condition compared to all other conditions (p<0.05). In summary, dexamethasone has no independent effect on serum leptin in the absence of food intake. Rather, dexamethasone appears to potentiate the food-induced increase in serum leptin. This synergism may be mediated by insulin and/or other factors associated with food ingestion.

A ca. 40 kDa maize (Zea mays L.) embryo dehydrin is encoded by the dhn2 locus on chromosome 9

Dehydrins (LEA D11 proteins) are the products of multigene families in a number of higher plants. To date, however, only one dehydrin locus, dhn1 (a major embryo and drought-induced protein of ca. 18 kDa) has been placed on chromosome 6L of the genetic linkage map of maize. The presence of a larger, ca. 40 kDa embryo protein that is also specifically detected by anti-dehydrin antibodies had been observed in some maize inbreds, including B73, suggesting that other dhn loci may exist. The ca. 22 kDa and ca. 40 kDa immunopositive proteins were purified from B73 and their amino acid compositions determined. The two proteins' amino acid compositions are typical of dehydrins, yet they differ from each other, indicating that they are distinct dhn gene products. Different size alleles for both proteins, or presence/absence in the case of the ca. 40 kDa protein, were evident from comparisons of embryo proteins of various maize inbreds. Analysis of segregating F2 progeny derived from self-pollination of F1 hybrids from four crosses (B73 x OH43, Mo17 x A632, AHO x A632, Latente x A632) revealed that alleles of the two genes assort independently. Map positions of the two dhn loci were then determined using two maize recombinant inbred line (RIL) mapping populations. The predicted map position of the gene controlling production of the ca. 22 kDa protein confirmed that this protein is the product of the dhn1 gene. The gene encoding the ca. 40 kDa dehydrin-like protein maps to a new locus on chromosome 9S near wx1, which we have named dhn2.

Impact of abnormal second-trimester maternal serum single, double, and triple screening on patient choices about prenatal diagnosis

The development of multiple-marker biochemical screening has increased the percentage of aneuploidies detected for all age groups and has also increased the abnormality/amniocentesis ratio from about 1 in 85 for maternal serum alpha-fetoprotein alone (single screening) to about 1 in 50 for either maternal serum alpha-fetoprotein plus human chorionic gonadotropin (double screening) or maternal serum alpha-fetoprotein combined with human chorionic gonadotropin and unconjugated estriol (triple screening). We evaluated the decisions to have or decline amniocentesis of 985 patients 'at risk' by either single, double, or triple screening, as multiple markers were phased in over a 3-year period. The patient acceptance of the procedure did not change (approximately 80%) either by actual risk or type of biochemical screening. The labeling of 'at risk' status is more important than actual numerical risks, and the patient perception of risk status must be considered in counseling.

Pregnancy outcome when both members of a couple have balanced translocations

BACKGROUND

Couples in which one partner is the carrier of a balanced translocation have increased risks of infertility, recurrent abortion, and delivery of chromosomally abnormal offspring. Pregnancies in which both partners carry balanced translocations are uncommon; therefore, only limited information regarding risk figures is available. We present a couple in which both members had a balanced translocation and discuss their pregnancy outcomes.

CASE

A couple had three first-trimester spontaneous abortions at 12, 10, and 8 weeks' gestation, respectively. Both partners were found to be carriers of balanced autosomal translocations. The mother had a Robertsonian translocation with the karyotype 45,XX,t(13q14q). The father had a reciprocal translocation with a 46,XY,t(1;4)(q32;q25) karyotype. There was no information regarding the karyotype of the patient's first-born child with a previous partner. The patient's first-born child with her current partner carried a double balanced translocation karyotype of 45,XX,t(13;14)t(1;4). Their second and third children both had a 45,XX,t(13q14q) karyotype.

CONCLUSION

Couples in which both members have a balanced translocation are at increased risk for adverse pregnancy and fetal outcomes, but precise information regarding risk estimates for this rare circumstance is limited. Genetic counseling of such couples therefore presents a unique challenge.

Management of small unilateral renal cell carcinomas: radical versus nephron-sparing surgery

OBJECTIVES

There is controversy concerning the management of small unilateral renal cell carcinomas. The present study was undertaken to evaluate the relative efficacy of radical nephrectomy versus nephron-sparing surgery in such patients.

METHODS

Patients with a single, small (less than 4 cm), localized, unilateral, sporadic renal cell carcinoma (RCC) were identified from an institutional registry. From 1975 to 1992, 88 patients fulfilling these criteria were treated with either radical nephrectomy (n = 42) or nephron-sparing surgery (n = 46). The mean postoperative follow-up interval is 48 +/- 29 months.

RESULTS

The radical and nephron-sparing surgical groups were well matched for patient age, sex, renal function, diabetes, hypertension, tumor size, tumor location, and tumor stage. All patients in both groups had low pathologic stage RCC. There was no difference between the two groups in terms of the mean hospital stay, the requirement for blood transfusions, or the occurrence of surgical complications. There was no difference in the mean preoperative and postoperative serum creatinine levels for patients in the nephron-sparing surgery group. However, the mean postoperative serum creatinine levels were significantly higher than the mean preoperative levels for patients in the radical nephrectomy group (P < 0.001). A single patient in each group developed recurrent RCC postoperatively. The cancer-specific 5-year survival rate for patients in the radical and nephron-sparing surgical groups is 97% and 100%, respectively.

CONCLUSIONS

Radical nephrectomy and nephron-sparing surgery each provide safe and effective curative treatment for patients with a single, small, unilateral localized RCC. The long-term renal functional advantage of nephron-sparing surgery in this setting is not established.

Use of molybdenum telluride as a substrate for the imaging of biological molecules during scanning tunnelling microscopy

Scanning tunnelling microscopy was used to image biological molecules including supercoiled deoxyribonacetic acid and specific retrovirus enzymes, the reverse transcriptases of the avian myeloblastosis virus, the moloney murine leukaemia virus and the human immunodeficiency virus. Measurements were carried out on graphite and Group VI transition metal dichalcogenide layered crystals. Images obtained with graphite could not be unequivocally interpreted and attachment appears to occur solely at surface defect sites. The layered crystal MoTe2 shows different imaging properties. The bimolecules are clearly visible, distributed over the semiconductor surface, and the molecular shapes and dimensions show good correlation with structure predictions.

Direct observation of reverse transcriptases by scanning tunneling microscopy

First images on a nanometer scale of reverse transcriptases (RT) of the human immunodeficiency virus (HIV-1) and of the Moloney murine leukemia virus (MuLV) obtained by scanning tunneling microscopy (STM) are reported. The common feature of the observed molecules is a ring-type or horseshoe shape with hole diameters of approximately 30 A. The STM images are compared with high resolution transmission electron microscopy (TEM) and existing structure predictions. The similarities of the structural data obtained by STM and TEM and their agreement with the structure prediction for the RT of HIV-1 shows the principal possibility to image such biomolecules by STM.

Scanning tunnelling microscopy observations of biomolecules on layered materials

Scanning tunnelling microscopy (STM) has been performed on the reverse transcriptases of the human immunodeficiency virus (HIV-1) and the moloney murine leukaemia virus (MuLV). The biological molecules are adsorbed on n-type semiconducting MoTe2. The p66 (66 kD) subunit of the RT of HIV-1 is imaged by STM. Both STM and processed transmission electron microscopy (TEM) data show a spherical and horseshoe-like shape of external diameter ca. 65 A, depending on the angle of observation. The STM results show a larger diameter which is related to the curvature radius of the tip of the probing needle. The RTs of HIV-1 and MuLV exhibit a circular hole of ca. 20 A diameter in accordance with structure predictions and functioning considerations. The surface-molecule interaction is discussed in terms of the electronic properties of the semiconductor surface including the influence of small defect sites at the layered crystal surface.

Late effects of childhood malignancies seen in Western Australia

Eighty-nine pediatric oncology patients, in remission and off treatment for at least 4 years, were reviewed annually in the Late Effects Clinic of Princess Margaret Hospital for Children in Perth, Western Australia. Interval from time of diagnosis to follow-up ranged from 4 to 23 years (mean 10.8 years). Acute lymphoblastic leukemia (ALL) (40%) and Wilms' tumor (27%) were the most common primary malignancies in this group. Late sequelae included musculoskeletal abnormalities (23 children), growth hormone deficiency (11), second tumors (9), learning difficulties (7), puberty and fertility problems (4), and hypothyroidism (4). These complications were most often related to radiation therapy. The need for prolonged, regular follow-up of survivors of childhood malignancy for early detection of late sequelae and subsequent intervention is stressed.

Oral activity of the growth hormone releasing peptide His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 in rats, dogs and monkeys

The purpose of this study was to evaluate the growth hormone (GH) releasing activity of orally administered His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 (GHRP-6, SK&F 110679) in rats, dogs and monkeys. Rats were administered GHRP-6 orally by gavage or parenterally through femoral artery catheters. Blood was collected before and after GHRP-6 administration for estimation of plasma GH and comparison of GH changes resulting from enteral and parenteral administration of the peptide. GHRP-6 was administered to dogs intravenously (i.v.) through cephalic vein catheters, intragastrically (i.g.) through esophagostomy tubes or intraduodenally (i.d.) through vascular access ports, and blood was collected before and after peptide administration for estimation of plasma GH. Cynomolgus monkeys were administered GHRP-6 i.g., and blood was collected from abdominal aorta for estimation of changes in plasma GH. Enteral activity of GHRP-6 was observed in all 3 species tested. In rats, ED50's for enteral and parenteral administration of GHRP-6 were 4 mg/kg and 28 micrograms/kg, respectively. Thus in rats, enterally administered GHRP-6 was 0.7% as bioactive as the parenterally administered peptide. In dogs GHRP-6 was slightly less potent than in rats, with ED50's for i.g. and i.v. administration approximately 15 mg/kg and 125 micrograms/kg, respectively. However, enteral potency of GHRP-6 in dogs was 0.8% of parenteral potency, and thus, comparable to that in rats. Additionally, comparison of plasma GH levels following i.g. vs i.d. administration in dogs suggested greater activity by the i.d. route. Monkeys were the species most sensitive to enterally administered GHRP-6, with plasma GH increased in those receiving i.g. doses as low as 0.3 mg/kg and an ED50 of 0.75 mg/kg compared to 4 and 15 mg/kg in rats and dogs, respectively. The results of this study demonstrate that GHRP-6 releases GH when administered directly into the gastrointestinal tract. Although enteral activity is approximately 1% of parenteral activity, GHRP-6 is potent, especially in primates which require relatively low doses to provoke GH release. These data suggest that orally active GHRP-6 may provide a practical therapeutic alternative to parenterally administered peptides such as GHRH, especially if enteral activity is enhanced with appropriate formulation.

A new portacaval shunt

A new prosthetic, segmented polyether polyurethane portacaval shunt featuring quick-connect anastomotic ends was constructed and evaluated as part of a short-term pharmacokinetic study. The shunts were easily implanted, did not require the use of anticoagulants, and decreased the operative time normally required for this surgical preparation. There was no evidence of thrombosis or venous stasis associated with the shunts.

Some effects of limited exercise on purpose-bred beagles

Amendments to the Animal Welfare Act (PL 99-198) require that an exercise program for dogs be established by the attending veterinarian. A 6-week study was conducted to determine the effects of a moderate exercise program in purpose-bred Beagles. Sixteen male Beagles (4/group) were maintained as follows: (1) standard cage without exercise; (2) standard cage with individual exercise periods (35 minutes, 3 times/week); (3) large cage without exercise; and (4) standard cage with group-release exercise periods. Blood samples were collected for CBC, serum biochemical analysis including determination of serum cortisol concentration, and immune function (lymphocyte transformation assay). Group-released dogs interacted with each other during most of the exercise time. Fighting in these dogs occurred only during the third week. Dogs had little inclination to exercise when released alone into the exercise area. Regardless of the size of the cage, dogs did not exercise unless human beings were present in the room. There were no significant differences in laboratory findings among dogs in the 4 groups. This moderate exercise program had no demonstrable effects. Similarly, continuous cage housing, without a formal exercise program, could not be determined to be detrimental to the physiologic or health status of dogs.