Comparative Analysis of Antibody Titers against the Spike Protein of SARS-CoV-2 Variants in Infected Patient Cohorts and Diverse Vaccination Regimes

The presence of neutralizing antibodies against SARS-CoV-2 correlates with protection against infection and severe COVID-19 disease courses. Understanding the dynamics of antibody development against the SARS-CoV-2 virus is important for recommendations on vaccination strategies and on control of the COVID-19 pandemic. This study investigates the dynamics and extent of α-Spike-Ab development by different vaccines manufactured by Johnson & Johnson, AstraZeneca, Pfizer-BioNTech and Moderna. On day 1 after vaccination, we observed a temporal low-grade inflammatory response. α-Spike-Ab titers were reduced after six months of vaccination with mRNA vaccines and increased 14 days after booster vaccinations to a maximum that exceeded titers from mild and critical COVID-19 and Long-COVID patients. Within the group of critical COVID-19 patients, we observed a trend for lower α-Spike-Ab titers in the group of patients who survived COVID-19. This trend accompanied higher numbers of pro-B cells, fewer mature B cells and a higher frequency of T follicular helper cells. Finally, we present data demonstrating that past infection with mild COVID-19 does not lead to long-term increased Ab titers and that even the group of previously infected SARS-CoV-2 patients benefit from a vaccination six months after the infection.

Differential diagnostic performance of a panel of plasma biomarkers for different types of dementia

Introduction

We explored what combination of blood‐based biomarkers (amyloid beta [Aβ]_{1‐42/1‐40}, phosphorylated tau [p‐tau]181, neurofilament light [NfL], glial fibrillary acidic protein [GFAP]) differentiates Alzheimer's disease (AD) dementia, frontotemporal dementia (FTD), and dementia with Lewy bodies (DLB).

Methods

We measured the biomarkers with Simoa in two separate cohorts (n = 160 and n = 152). In one cohort, Aβ_{1‐42/1‐40} was also measured with mass spectrometry (MS). We assessed the differential diagnostic value of the markers, by logistic regression with Wald's backward selection.

Results

MS and Simoa Aβ_{1‐42/1‐40} similarly differentiated AD from controls. The Simoa panel that optimally differentiated AD from FTD consisted of NfL and p‐tau181 (area under the curve [AUC] = 0.94; cohort 1) or NfL, GFAP, and p‐tau181 (AUC = 0.90; cohort 2). For AD from DLB, the panel consisted of NfL, p‐tau181, and GFAP (AUC = 0.88; cohort 1), and only p‐tau181 (AUC = 0.81; cohort 2).

Discussion

A combination of plasma p‐tau181, NfL, and GFAP, but not Aβ_{1‐42/1‐40}, might be useful to discriminate AD, FTD, and DLB.

Characterization of pre-analytical sample handling effects on a panel of Alzheimer's disease-related blood-based biomarkers: Results from the Standardization of Alzheimer's Blood Biomarkers (SABB) working group

Introduction

Pre‐analytical sample handling might affect the results of Alzheimer's disease blood‐based biomarkers. We empirically tested variations of common blood collection and handling procedures.

Methods

We created sample sets that address the effect of blood collection tube type, and of ethylene diamine tetraacetic acid plasma delayed centrifugation, centrifugation temperature, aliquot volume, delayed storage, and freeze–thawing. We measured amyloid beta (Aβ)42 and 40 peptides with six assays, and Aβ oligomerization‐tendency (OAβ), amyloid precursor protein (APP)_699‐711, glial fibrillary acidic protein (GFAP), neurofilament light (NfL), total tau (t‐tau), and phosphorylated tau181.

Results

Collection tube type resulted in different values of all assessed markers. Delayed plasma centrifugation and storage affected Aβ and t‐tau; t‐tau was additionally affected by centrifugation temperature. The other markers were resistant to handling variations.

Discussion

We constructed a standardized operating procedure for plasma handling, to facilitate introduction of blood‐based biomarkers into the research and clinical settings.

Does a single adjustment in the meat standards Australia beef grading model cater for different hormonal growth promotant formulations?

This paper investigated whether a single Hormonal Growth Promotant (HGP) adjustment in the Meat Standards Australia (MSA) beef grading model adequately predicted consumer eating quality of beef from cattle treated with different HGP formulations. This paper used consumer sensory data from two experiments. In experiment one, a total of 300 steers were allocated to three treatments; control (CON-100-F), 100 day oestradiol only HGP (OES-100-F), or a combination of trenbolone acetate and oestradiol HGP (TBA+OES-100-F) and finished in a feedlot for 73 days. In experiment two, a total of 200 steers were allocated either control or 400 day oestradiol only HGP treatments and finished on pasture for 389 days. Steers were slaughtered by finishing regime and carcass traits recorded. The anterior and posterior portions of the m. longissimus lumborum (LL-A and LL-P, respectively) and m. gluteus medius (GM) were collected and aged for five or 35 days. Grilled meat samples were scored for tenderness, juiciness, liking of flavour and overall acceptability using untrained consumers. Sensory scores were weighted by 0.3. 0.1, 0.3 and 0.3, respectively and summed to calculate a meat quality (MQ4) score. Residual MQ4 scores were calculated (observed MQ4 minus the predicted MQ4 score). The MSA model accounts for varied impacts of different HGPs on eating quality through a single HGP adjustment, and indirect impacts on carcass traits. For the majority of the HGP treatment samples, the residual MQ4 scores were not different to zero (5/18), or were positive i.e. the MSA model under-predicted these samples (11/18). Under-prediction was predominately for 35 day aged (7/9) and GM HGP treatment samples (6/6) and was considered low, with the majority less than ±5 MQ4 units. Under-prediction could be considered as advantageous through providing an additional safeguard to protect the interests of the consumers, rather than if the model had over-predicted and resulted in a more negative eating quality experience than expected. Some over-prediction was observed in the CON-100-F and TBA+OES-100-F treatment samples, which may be due to factors such as genetic variation and/or production environment. Minimal bias was observed when residual MQ4 was regressed against predicted MQ4 for the range of feeding regimes, muscles, ageing periods and treatment groups. This study showed that a single HGP adjustment in the MSA beef grading model, combined with the indirect effects of the different HGP formulations on carcass traits, provided a reasonable prediction of meat eating quality for different HGP formulations.

N-protein presents early in blood, dried blood and saliva during asymptomatic and symptomatic SARS-CoV-2 infection

The COVID-19 pandemic continues to have an unprecedented impact on societies and economies worldwide. There remains an ongoing need for high-performance SARS-CoV-2 tests which may be broadly deployed for infection monitoring. Here we report a highly sensitive single molecule array (Simoa) immunoassay in development for detection of SARS-CoV-2 nucleocapsid protein (N-protein) in venous and capillary blood and saliva. In all matrices in the studies conducted to date we observe >98% negative percent agreement and >90% positive percent agreement with molecular testing for days 1-7 in symptomatic, asymptomatic, and pre-symptomatic PCR+ individuals. N-protein load decreases as anti-SARS-CoV-2 spike-IgG increases, and N-protein levels correlate with RT-PCR Ct-values in saliva, and between matched saliva and capillary blood samples. This Simoa SARS-CoV-2 N-protein assay effectively detects SARS-CoV-2 infection via measurement of antigen levels in blood or saliva, using non-invasive, swab-independent collection methods, offering potential for at home and point of care sample collection.

Performance Comparison of Two Anaesthetic Facemasks

When considering anaesthetic masks, the quality of the mask-face seal is a key determinant of performance. This randomised crossover trial utilises expired oxygen concentration to compare the efficacy of two routinely used facemasks. Thirty subjects were randomised to breathe 100% oxygen via either a traditional reusable black rubber mask or the disposable Intersurgical Scented mask for three minutes. This was then repeated using the other mask. To compare the impact of mask design on the quality of the mask-face seal, it was necessary to minimise measures taken by the anaesthetist to correct for a poor seal. To achieve this, the anaesthetist was requested to hold the mask in a manner consistent with an airtight seal, but they were blinded to capnography and reservoir bag movement. Expired oxygen concentration was recorded at 15-second intervals. From the oxygen wash-in curves, the Intersurgical mask consistently outperformed the black rubber mask. At three minutes the Intersurgical mask performed better than the black rubber mask, with mean end-tidal oxygen concentrations of 86.9% vs. 81% respectively; P=0.008. These findings indicate that the soft cuff design of the intersurgical mask provided a better seal than the black rubber facemask.

COMETARY SCIENCE. Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov-Gerasimenko

Thermal and mechanical material properties determine comet evolution and even solar system formation because comets are considered remnant volatile-rich planetesimals. Using data from the Multipurpose Sensors for Surface and Sub-Surface Science (MUPUS) instrument package gathered at the Philae landing site Abydos on comet 67P/Churyumov-Gerasimenko, we found the diurnal temperature to vary between 90 and 130 K. The surface emissivity was 0.97, and the local thermal inertia was 85 ± 35 J m(-2) K(-1)s(-1/2). The MUPUS thermal probe did not fully penetrate the near-surface layers, suggesting a local resistance of the ground to penetration of >4 megapascals, equivalent to >2 megapascal uniaxial compressive strength. A sintered near-surface microporous dust-ice layer with a porosity of 30 to 65% is consistent with the data.

Carcase weight and dressing percentage are increased using Australian Sheep Breeding Values for increased weight and muscling and reduced fat depth

Pre-slaughter live weight, dressing percentage, and hot standard carcase weight (HCWT) from the 2007, 2008, 2009 and 2010 birth-years of the Information Nucleus Flock Lambs (n=7325) were analysed using linear mixed effects models. Increasing the sire breeding value for post-weaning weight (PWWT), and c-site eye muscle depth (PEMD), and reducing the sire breeding value for fat depth (PFAT) all had positive impacts on HCWT. The magnitude of the PWWT effect was greater in pure bred Merinos compared to Maternal and Terminal sired progeny. The improved HCWT resulting from increased PEMD was entirely due to its impact on improving dressing percentage, given that it had no impact on pre-slaughter live weight. There were marked differences between sire types and dam breeds, with pure-bred Merinos having lower pre-slaughter weight, reduced dressing percentage, and lower HCWT than progeny from Terminal and Maternal sired lambs or progeny from Maternal (1st cross) dams.

Genetic parameters for meat quality traits of Australian lamb meat

Genetic parameters were estimated for a range of meat quality traits recorded on Australian lamb meat. Data were collected from Merino and crossbred progeny of Merino, terminal and maternal meat breed sires of the Information Nucleus programme. Lambs born between 2007 and 2010 (n=8968) were slaughtered, these being the progeny of 372 sires and 5309 dams. Meat quality traits were found generally to be of moderate heritability (estimates between 0.15 and 0.30 for measures of meat tenderness, meat colour, polyunsaturated fat content, mineral content and muscle oxidative capacity), with notable exceptions of intramuscular fat (0.48), ultimate pH (0.08) and fresh meat colour a* (0.08) and b* (0.10) values. Genetic correlations between hot carcass weight and the meat quality traits were low. The genetic correlation between intramuscular fat and shear force was high (-0.62). Several measures of meat quality (fresh meat redness, retail meat redness, retail oxy/met value and iron content) appear to have potential for inclusion in meat sheep breeding objectives.

Associations of genetic and non-genetic factors with concentrations of iron and zinc in the longissimus muscle of lamb

There is a concern regarding the possible decline of nutritional value of meat with an increasing selection for lean meat yield. The selection for reduced fatness reduces muscle aerobicity and possible subsequent mineral concentrations. Average concentrations of iron and zinc of 5625 lamb longissimus muscles were 2.03 and 2.43 mg/100 g, qualifying as a good source claim for the majority of the population. Reduced post-weaning fat depth was associated with decreased concentrations of iron but not zinc, whereas post-weaning eye muscle depth and weaning weight were not associated with either mineral. These results confirm that the impact of lean meat yield selection on these minerals is minimal, but should be monitored to avoid lower levels. Both minerals had a positive relationship with age at slaughter, highlighting age as a key determinant of the concentration of these nutrients. The magnitude of the positive associations of isocitrate dehydrogenase and myoglobin with iron was larger than for zinc, but they strongly indicated the association of these aerobic makers with both minerals.

Intramuscular fat in the longissimus muscle is reduced in lambs from sires selected for leanness

Selection for lean growth through Australian Sheep Breeding Values (ASBVs) for post weaning weight (PWWT), eye muscle depth (PEMD) and c-site fat depth (PFAT) raises concerns regarding declining intramuscular fat (IMF) levels. Reducing PFAT decreased IMF by 0.84% for Terminal sired lambs. PEMD decreased IMF by 0.18% across all sire types. Female lambs had higher IMF levels and this was unexplained by total carcass fatness. The negative phenotypic association between measures of muscling (shortloin muscle weight, eye muscle area) and IMF, and positive association between fatness and IMF, was consistent with other literature. Hot carcass weight increased IMF by 2.08% between 12 and 40 kg, reflective of development of IMF as lambs approach maturity. Selection objectives with low PFAT sires will reduce IMF, however the lower impact of PEMD and absence of a PWWT effect, will enable continued selection for lean growth without influencing IMF. Alternatively, the negative impact of PFAT could be off-set by inclusion of an IMF ASBV.

Nonproteasomal targets of the proteasome inhibitors bortezomib and carfilzomib: a link to clinical adverse events

PURPOSE

Bortezomib (Velcade), a dipeptide boronate 20S proteasome inhibitor and an approved treatment option for multiple myeloma, is associated with a treatment-emergent, painful peripheral neuropathy (PN) in more than 30% of patients. Carfilzomib, a tetrapeptide epoxyketone proteasome inhibitor, currently in clinical investigation in myeloma, is associated with low rates of PN. We sought to determine whether PN represents a target-mediated adverse drug reaction (ADR).

EXPERIMENTAL DESIGN

Neurodegenerative effects of proteasome inhibitors were assessed in an in vitro model utilizing a differentiated neuronal cell line. Secondary targets of both inhibitors were identified by a multifaceted approach involving candidate screening, profiling with an activity-based probe, and database mining. Secondary target activity was measured in rats and patients receiving both inhibitors.

RESULTS

Despite equivalent levels of proteasome inhibition, only bortezomib reduced neurite length, suggesting a nonproteasomal mechanism. In cell lysates, bortezomib, but not carfilzomib, significantly inhibited the serine proteases cathepsin G (CatG), cathepsin A, chymase, dipeptidyl peptidase II, and HtrA2/Omi at potencies near or equivalent to that for the proteasome. Inhibition of CatG was detected in splenocytes of rats receiving bortezomib and in peripheral blood mononuclear cells derived from bortezomib-treated patients. Levels of HtrA2/Omi, which is known to be involved in neuronal survival, were upregulated in neuronal cells exposed to both proteasome inhibitors but was inhibited only by bortezomib exposure.

CONCLUSION

These data show that bortezomib-induced neurodegeneration in vitro occurs via a proteasome-independent mechanism and that bortezomib inhibits several nonproteasomal targets in vitro and in vivo, which may play a role in its clinical ADR profile.

A neuronal and astrocyte co-culture assay for high content analysis of neurotoxicity

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing measurement of multiple cellular phenotypes within a single assay. In this study, we utilized HCA to develop a novel assay for neurotoxicity. Neurotoxicity assessment represents an important part of drug safety evaluation, as well as being a significant focus of environmental protection efforts. Additionally, neurotoxicity is also a well-accepted in vitro marker of the development of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Recently, the application of HCA to neuronal screening has been reported. By labeling neuronal cells with betaIII-tubulin, HCA assays can provide high-throughput, non-subjective, quantitative measurements of parameters such as neuronal number, neurite count and neurite length, all of which can indicate neurotoxic effects. However, the role of astrocytes remains unexplored in these models. Astrocytes have an integral role in the maintenance of central nervous system (CNS) homeostasis, and are associated with both neuroprotection and neurodegradation when they are activated in response to toxic substances or disease states. GFAP is an intermediate filament protein expressed predominantly in the astrocytes of the CNS. Astrocytic activation (gliosis) leads to the upregulation of GFAP, commonly accompanied by astrocyte proliferation and hypertrophy. This process of reactive gliosis has been proposed as an early marker of damage to the nervous system. The traditional method for GFAP quantitation is by immunoassay. This approach is limited by an inability to provide information on cellular localization, morphology and cell number. We determined that HCA could be used to overcome these limitations and to simultaneously measure multiple features associated with gliosis - changes in GFAP expression, astrocyte hypertrophy, and astrocyte proliferation - within a single assay. In co-culture studies, astrocytes have been shown to protect neurons against several types of toxic insult and to critically influence neuronal survival. Recent studies have suggested that the use of astrocytes in an in vitro neurotoxicity test system may prove more relevant to human CNS structure and function than neuronal cells alone. Accordingly, we have developed an HCA assay for co-culture of neurons and astrocytes, comprised of protocols and validated, target-specific detection reagents for profiling betaIII-tubulin and glial fibrillary acidic protein (GFAP). This assay enables simultaneous analysis of neurotoxicity, neurite outgrowth, gliosis, neuronal and astrocytic morphology and neuronal and astrocytic development in a wide variety of cellular models, representing a novel, non-subjective, high-throughput assay for neurotoxicity assessment. The assay holds great potential for enhanced detection of neurotoxicity and improved productivity in neuroscience research and drug discovery.

Reduced susceptibility to DDT in field populations of Anopheles quadriannulatus and Anopheles arabiensis in Malawi: evidence for larval selection

Bioassays for insecticide resistance in adult mosquitoes were conducted on samples of Anopheles gambiae Giles s.l. (Diptera: Culicidae) species collected as larvae from breeding sites in the lower Shire Valley, Malawi. The results indicate full susceptibility to permethrin, deltamethrin and malathion, but reduced susceptibility to DDT in one sample from Thom (LT(50) of 8.39 min for females and 25.09 min for males). Polymerase chain reaction-based species identification of the mosquitoes assayed revealed a mixture of Anopheles arabiensis Patton and Anopheles quadriannulatus (Theobold). The LT(50) did not differ significantly between species. Genotyping of the L1014F and L1014S kdr alleles showed all mosquito specimens to be homozygous wild type; thus the reduced susceptibility detected is not attributable to target site insensitivity and instead is likely to be metabolic in nature. Anopheles quadriannulatus is characteristically zoophagic and exophilic. Indeed, of 82 Anopheles collected through knockdown collections within dwellings, only one was An. quadriannulatus and the rest were An. arabiensis. They are unlikely, therefore, to have been exposed to selection pressure arising from insecticide-treated net usage or to DDT indoor residual spraying. Therefore, it is suggested that this example of reduced susceptibility to DDT in An. quadriannulatus reflects selection in the larval stages.

Condom perforation during transrectal ultrasound guided (TRUS) prostate biopsies: a potential infection risk

INTRODUCTION

Transrectal ultrasound (TRUS) guided prostate biopsies are amongst the most common outpatient diagnostic procedures performed in urology practice. Of concern appear to be recent reports of infectious complications following this procedure in which contamination of the biopsy equipment was the likely source. This study looks at the rate of condom perforation during prostate biopsy and we look to highlight the potential problems, which may arise as a result of inadequate cleansing of the equipment between cases during a busy prostate biopsy clinic

MATERIAL AND METHODS

All patients attending for prostate biopsies over a three-month period in our institution were included in the study. All condoms (latex) used were made by the same manufacturer and were checked prior to the procedure and found to have no leaks. The biopsy gun was inserted through an externally placed needle guide, as is standard practice in many departments in the UK. After the end of each procedure the condom was removed from the rectal probe and filled once again with water to assess for perforations. Two experienced surgeons carried out all the procedures.

RESULTS

10 out of 107 patients were found to have at least one perforation in the condom. In some of the condoms there were multiple perforations.

DISCUSSION

We have demonstrated a significant condom perforation rate (9%) amongst patients undergoing prostate biopsies. This raises the serious issue of hygiene and cross infection, particularly with blood borne communicable diseases such as hepatitis and HIV unless strict disinfection and sterilization protocols are followed between patients. Perforation of the condoms used during TRUS guided prostate biopsy and hence faecal and blood contamination of the biopsy equipment could potentially have far-reaching implications for urologists and the infection control community. Although the risk of cross infection is probably small this serious issue needs addressing.

HES6 reverses nuclear reprogramming of insulin-producing cells following cell fusion

To examine the mechanism by which growth-stimulated pancreatic beta-cells dedifferentiate, somatic cell fusions were performed between MIN6, a highly differentiated mouse insulinoma, and betalox5, a cell line derived from human beta-cells which progressively dedifferentiated in culture. MIN6/betalox5 somatic cells hybrids underwent silencing of insulin expression and a marked decline in PDX1, NeuroD, and MafA, indicating that betalox5 expresses a dominant transacting factor(s) that represses beta-cell differentiation. Expression of Hes1, which inhibits endocrine differentiation was higher in hybrid cells than in parental MIN6 cells. Hes6, a repressor of Hes1, was highly expressed in primary beta-cells as well as MIN6, but was repressed in hybrids. Hes6 overexpression using a retroviral vector led to a decrease in Hes1 levels, an increase in beta-cell transcription factors and partial restoration of insulin expression. We conclude that the balance of Notch activators and inhibitors may play an important role in maintaining the beta-cell differentiated state.

Functional effects and characteristics of cecum-projecting neurons in the dorsal motor nucleus of the vagus of rats

Preganglionic neurons in the dorsal motor nucleus of the vagus (DMV) innervate most of the gastrointestinal tract; with the stomach and the cecum/proximal colon having a greater proportion of vagal input. Cecum-projecting neurons have been thought to be distinct from other preganglionic neurons due to their location within the DMV, but it is unknown whether these neurons innervate the cecum exclusively or what effect their activation has on cecal motor activity. Therefore, we investigated the extent of coinnervation of cecum and stomach by vagal neurons, their neurochemistry, and the effect of DMV stimulation on intracecal and intragastric volumes. Fluorescent retrograde tracers injected into the serosa of the cecum and stomach revealed that in the DMV 49+/-5% CTB-labeled cecum-projecting neurons also innervated the stomach. Immunocytochemical staining for nitric oxide (NO) synthase and tyrosine hydroxylase indicated that only 3+/-1% and 4+/-1% of cecum-projecting neurons contained these markers, respectively. In anesthetized rats gastric and cecal volumes were measured by prototypic miniaturized dual barostats that were developed for use in rodents. Microinjection of l-glutamate into the DMV increased gastric contractile activity and tone, and reduced on-going cecum contractile activity (2.6+/-0.7 contractions/2 min after injection versus 8.2+/-0.4 contractions/2 min before injection, N = 5). The barostat was able to detect decreases (-0.88+/-0.13 ml) and increases (0.25+/-0.05 ml) in cecum volume in response to carbachol and sodium nitroprusside, respectively. In summary, cecum-projecting neurons are not an entirely exclusive population within the DMV because a percentage of these also innervate the stomach. Central vagal stimulation can modulate both gastric and cecum contractile activity. Together, these data support a role of the vagus in neural reflexes involving gastric and large bowel motor function, such as the immediate phase of the gastrocolonic reflex.

Intravesical explosions during transurethral endoscopic procedures

Every Urologist, during the course of fulguration treatment of bladder tumours, has at some time or another experienced small intravesical explosions usually manifesting as a "pop". Major intravesical explosions are rare but potentially devastating complications of transurethral endoscopic resections. The damage to the bladder can range from small mucosal tears to bladder rupture, which can either be intraperitoneal (requiring laparotomy and open bladder repair) or extraperitoneal. We review the literature on intravesical explosions to determine the aetiology of these explosions and suggest strategies to prevent these. A comprehensive literature search was performed using Medline and Ovid to obtain information using search terms: intravesical explosions, transurethral procedures, endoscopic procedures, diathermyIntravesical explosions occur due to the production of explosive gases during use of diathermy on human tissues. The most dangerous combination is hydrogen and oxygen. Hydrogen alone is not explosive and it only becomes explosive when admixed with oxygen. Oxygen is not produced in sufficient quantity during diathermy to cause explosions but can enter into the bladder from the atmosphere during endoscopic procedures. Careful operative technique (correct use of the Ellick evacuator bulb and reducing the frequency of manual irrigations of the bladder) with minimisation of the operative time and using the coagulation current at moderate power as well as judicious coagulation of tissues can reduce the risk of this dangerous complication arising.

Actions of glucagon-like peptide-1 on KATP channel-dependent and -independent effects of glucose, sulphonylureas and nateglinide

This study examined the effects of glucagon-like peptide-1 (GLP-1) on insulin secretion alone and in combination with sulphonylureas or nateglinide, with particular attention to K(ATP) channel-independent insulin secretion. In depolarised cells, GLP-1 significantly augmented glucose-induced K(ATP) channel-independent insulin secretion in a glucose concentration-dependent manner. GLP-1 similarly augmented the K(ATP) channel-independent insulin-releasing effects of tolbutamide, glibenclamide or nateglinide. Downregulation of protein kinase A (PKA)- or protein kinase C (PKC)-signalling pathways in culture revealed that the K(ATP) channel-independent effects of sulphonylureas or nateglinide were critically dependent upon intact PKA and PKC signalling. In contrast, GLP-1 exhibited a reduced but still significant insulin-releasing effect following PKA and PKC downregulation, indicating that GLP-1 can modulate K(ATP) channel-independent insulin secretion by protein kinase-dependent and -independent mechanisms. The synergistic insulin-releasing effects of combinatorial GLP-1 and sulphonylurea/nateglinide were lost following PKA- or PKC-desensitisation, despite GLP-1 retaining an insulin-releasing effect, demonstrating that GLP-1 can induce insulin release under conditions where sulphonylureas and nateglinide are no longer effective. Our results provide new insights into the mechanisms of action of GLP-1, and further highlight the promise of GLP-1 or similarly acting analogues alone or in combination with sulphonylureas or meglitinide drugs in type 2 diabetes therapy.

In situ measurements of the physical characteristics of Titan's environment

On the basis of previous ground-based and fly-by information, we knew that Titan's atmosphere was mainly nitrogen, with some methane, but its temperature and pressure profiles were poorly constrained because of uncertainties in the detailed composition. The extent of atmospheric electricity ('lightning') was also hitherto unknown. Here we report the temperature and density profiles, as determined by the Huygens Atmospheric Structure Instrument (HASI), from an altitude of 1,400 km down to the surface. In the upper part of the atmosphere, the temperature and density were both higher than expected. There is a lower ionospheric layer between 140 km and 40 km, with electrical conductivity peaking near 60 km. We may also have seen the signature of lightning. At the surface, the temperature was 93.65 +/- 0.25 K, and the pressure was 1,467 +/- 1 hPa.

A soft solid surface on Titan as revealed by the Huygens Surface Science Package

The surface of Saturn's largest satellite--Titan--is largely obscured by an optically thick atmospheric haze, and so its nature has been the subject of considerable speculation and discussion. The Huygens probe entered Titan's atmosphere on 14 January 2005 and descended to the surface using a parachute system. Here we report measurements made just above and on the surface of Titan by the Huygens Surface Science Package. Acoustic sounding over the last 90 m above the surface reveals a relatively smooth, but not completely flat, surface surrounding the landing site. Penetrometry and accelerometry measurements during the probe impact event reveal that the surface was neither hard (like solid ice) nor very compressible (like a blanket of fluffy aerosol); rather, the Huygens probe landed on a relatively soft solid surface whose properties are analogous to wet clay, lightly packed snow and wet or dry sand. The probe settled gradually by a few millimetres after landing.

Hydrogen leak detection using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is investigated as a technique for real-time monitoring of hydrogen gas. Two methodologies were examined: The use of a 100 mJ laser pulse to create a laser-induced breakdown directly in a sample gas stream, and the use of a 55 mJ laser pulse to create a laser-induced plasma on a solid substrate surface, with the expanding plasma sampling the gas stream. Various metals were analyzed as candidate substrate surfaces, including aluminum, copper, molybdenum, stainless steel, titanium, and tungsten. Stainless steel was selected, and a detailed analysis of hydrogen detection in binary mixtures of nitrogen and hydrogen at atmospheric pressure was performed. Both the gaseous plasma and the plasma initiated on the stainless steel surface generated comparable hydrogen emission signals, using the 656.28 Halpha emission line, and exhibited excellent signal linearity. The limit of detection is about 20 ppm (mass) as determined for both methodologies, with the solid-initiated plasma yielding a slightly better value. Overall, LIBS is concluded to be a viable candidate for hydrogen sensing, offering a combination of high sensitivity with a technique that is well suited to implementation in field environments.

Alterations of insulin secretion following long-term manipulation of ATP-sensitive potassium channels by diazoxide and nateglinide

Previous studies have shown that prolonged exposure to drugs, which act via blocking KATP channels, can desensitize the insulinotropic effects of drugs and nutrients acting via KATP channels. In this study, effects of prolonged exposure to diazoxide, a KATP channel opener, on beta cell function were examined using clonal BRIN-BD11 cells. The findings were compared to the long-term effects of KATP channel blockers nateglinide and tolbutamide. Following 18 h exposure to 200 microM diazoxide, the amounts of insulin secreted in response to glucose, amino acids and insulinotropic drugs were increased. Secretory responsiveness to a variety of agents acting via KATP channels was retained following prolonged diazoxide exposure. In contrast, 18 h exposure to 100 microM nateglinide significantly attenuated the insulin secretory responses to tolbutamide, nateglinide and BTS 67 582. Glucose- and L-alanine-stimulated insulin release were unaffected by prolonged nateglinide exposure, however responsiveness to L-leucine and L-arginine was diminished. Prolonged exposure to nateglinide had no effect on forskolin- and PMA-stimulated insulin release, and the overall pattern of desensitization was similar to that induced by 100 microM tolbutamide. We conclude that in contrast to chronic long-term KATP channel blockade, long-term diazoxide treatment is not harmful to KATP channel mediated insulin secretion and may have beneficial protective effects on beta cell function.

Vanguard--a European robotic astrobiology-focussed Mars sub-surface mission proposal

We present a new European Mars mission proposal to build on the UK-led Beagle2 Mars mission and continue its astrobiology-focussed investigation of Mars. The small surface element to be delivered to the Martian surface--Vanguard--is designed to be carried by a Mars Express-type spacecraft bus to Mars and adopts a similar entry, descent and landing system as Beagle2. The surface element comprises a triad of robotic devices--a lander, a micro-rover of the Sojourner class for surface mobility, and three ground-penetrating moles mounted onto the rover for sub-surface penetration to 5 m depth. The major onboard instruments on the rover include a Raman spectrometer/imager, a laser plasma spectrometer, an infrared spectrometer--these laser instruments provide the basis for in situ "remote" sensing of the sub-surface Martian environment within a powerful scientific package. The moles carry the instruments' sensor head array to the sub-surface. The moles are thus required to undergo a one-way trip down the boreholes without the need for recovery of moles or samples, eliminating much of the robotic complexity invoked by such operations.

Telomere-independent cellular senescence in human fetal cardiomyocytes

Fetal cardiomyocytes have been proposed as a potential source of cell-based therapy for heart failure. This study examined cellular senescence in cultured human fetal ventricular cardiomyocytes (HFCs). HFCs were isolated and identified by immunocytochemistry and RT-PCR. Cells were found to senesce after 20-25 population doublings, as determined by growth arrest, morphological changes and senescence-associated beta-galactosidase activity. Using the telomeric repeat amplification protocol assay, telomerase activity was undetectable in primary HFCs. Cells were transduced to express the human reverse transcriptase subunit (hTERT) of telomerase. This resulted in greatly increased telomerase activity, but no significant lifespan extension. Analysis of telomere length in primary HFCs revealed that the senescent phenotype was not accompanied by telomere shortening. Telomeres in hTERT-positive cells were elongated in comparison with primary cells, and elongation was retained in senescent cells. Levels of the tumor suppressor protein p16INK4A increased in all senescent cells whether telomerase-positive or -negative. Senescence was accompanied by a decline in transcript levels of the polycomb gene Bmi-1, Ets1 and Ets2 transcription factors, and Id1, Id2 and Id3 helix-loop-helix proteins, suggesting roles for these genes in maintenance of cardiomyocyte proliferative capacity. In addition to offering novel insights into the behavior of human fetal cardiomyocytes in culture, these findings have implications for the development of a cell-based therapy for cardiac injury using primary fetal heart tissue.

Acute and long-term effects of nateglinide on insulin secretory pathways

Acute and chronic effects of the insulinotropic drug nateglinide upon insulin release were examined in the BRIN-BD11 cell line. Nateglinide (10-400 microm) stimulated a concentration-dependent increase (P<0.05-P<0.001) in insulin release at a non-stimulatory (1.1 mm) glucose concentration. The insulinotropic response to 200 microm nateglinide was increased at 30 mm (P<0.01), but not 5.6-16.7 mm glucose concentrations. In depolarized cells, nateglinide (50-200 microm) evoked K(ATP) channel-independent insulin secretion (P<0.05-P<0.001) in the absence and presence of 5.6-30.0 mm glucose (P<0.001). Exposure for 18 h to 100 microm nateglinide abolished the acute insulinotropic effects of 200 microm nateglinide, tolbutamide or glibenclamide, but had no effect upon the insulinotropic effect of 200 microm efaroxan. While 18 h exposure to 100 microm nateglinide did not affect basal insulin release or insulin release in the presence of 16.7 mm glucose, 25 microm forskolin or 10 nm PMA, significant inhibition of the insulinotropic effects of 20 mm leucine and 20 mm arginine were observed. These data show that nateglinide stimulates both K(ATP) channel-dependent and-independent insulin secretion. The maintained insulinotropic effects of this drug with increasing glucose concentrations support the antihyperglycaemic actions of nateglinide in Type II diabetes. Studies of the long-term effects of nateglinide indicate that nateglinide shares signalling pathways with sulphonylureas, but not the imidazoline efaroxan. This may be significant when considering a nateglinide treatment regimen, particularly in patients previously treated with sulphonylurea.

Chronic exposure to tolbutamide and glibenclamide impairs insulin secretion but not transcription of K(ATP) channel components

Clonal insulin-secreting BRIN-BD11 cells were used to examine effects of chronic 72-144 h exposure to the sulphonylureas tolbutamide and glibenclamide on insulin release, cellular insulin content, and mRNA levels of the Kir6.2 and SUR1 subunits of the beta-cell K(ATP) channel. Chronic exposure for 72-144 h to 5-100 microM tolbutamide and glibenclamide resulted in a time- and concentration-dependent irreversible decline in sulphonylurea-induced insulin secretion. In contrast, the decline in cellular insulin content induced by chronic exposure to high concentrations of sulphonylureas was readily reversible. Chronic exposure to tolbutamide or glibenclamide had no effect upon transcription of the Kir6.2 or SUR1 subunits of the pancreatic beta-cell K(ATP) channel. Whilst further studies are required to understand the precise nature of the chronic interactions of sulphonylurea with the insulin exocytotic mechanism, these observations may partially explain the well-known progressive failure of sulphonylurea therapy in type 2 diabetes.

Multiplex PCR assay for malaria vector Anopheles minimus and four related species in the Myzomyia Series from Southeast Asia

Mosquitoes (Diptera: Culicidae) of the Anopheles (Cellia) Myzomyia Series are important malaria vectors in Africa, India and Southeast Asia. Among 10 named species of Myzomyia known from the Oriental Region, seven form the An. minimus group. Even for expert taxonomists, the adults of these species remain difficult to identify morphologically. For technical staff of malaria control programmes, confusion may extend to misidentification of species that are not formally within the minimus group. For identification of specimens from Indochina (Cambodia, Laos, Vietnam), we describe a multiplex polymerase chain reaction (PCR) assay, based on rDNA internal transcribed spacer 2 (ITS2) sequences, that employs a cocktail of primers to identify An. minimus Theobald sibling species A and C (sensu; Green et al., 1990) and three other species in the An. minimus group (An. aconitus Dönitz, An. pampanai Büttiker & Beales, An. varuna Iyengar), as well as An. jeyporiensis James, also belonging to the Myzomyia Series. As the test is DNA-based, it can be applied to all life stages of these mosquitoes for ecological investigations and vector incrimination studies. This PCR assay is simpler, quicker, cheaper and more readily interpreted than previous assays.

Specific desensitization of sulfonylurea- but not imidazoline-induced insulin release after prolonged tolbutamide exposure

Functional effects of prolonged exposure to the sulfonylurea, tolbutamide, were examined in the clonal electrofusion-derived BRIN-BD11 cell line. In acute 20-min incubations, 50-400 microM tolbutamide stimulated a dose-dependent increase (P < 0.01) in insulin release at both non-stimulatory (1.1 mM) and stimulatory (8.4 mM) glucose. Culture with 100 microM tolbutamide (18 hr) caused a marked (67%) decrease in subsequent insulin-secretory responsiveness to acute challenge with 200 microM tolbutamide, though notably, tolbutamide culture exerted no influence on 200 microM efaroxan-induced insulin secretion. Duration of exposure (3-18 hr) to 100 microM tolbutamide in culture also time-dependently influenced subsequent responsiveness to acute tolbutamide challenge, with progressive 47-58% decreases from 6-18 hr (P < 0.001). Similarly, 6- to 18-hr culture with 100 microM efaroxan specifically desensitized efaroxan-induced insulin release. Tolbutamide- and efaroxan-induced desensitization exhibited a time-dependent reversibility, with a sustained return to full insulin-secretory responsiveness by 12 hr. Notably, 18-hr culture with tolbutamide or efaroxan did not significantly affect insulinotropic responses to 16.7 mM glucose, 10 mM 2-ketoisocaproic acid, 10 mM alanine, 10 mM arginine, or 30 mM KCl. Diverse inhibitory actions of tolbutamide or efaroxan culture on late events in stimulus-secretion coupling reveal that drug desensitization is both a specific and important phenomenon. As such, the model system described could prove an important tool in determining the complex modes of action of established and novel clinically useful insulinotropic compounds.

Stimulation of insulin secretion in clonal BRIN-BD11 cells by the imidazoline derivatives KU14r and RX801080

The imidazoline derivatives KU14R and RX801080 have each been reported to antagonize imidazoline-stimulated insulin secretion. This study investigated the effects of a range of concentrations of both KU14R and RX801080 on insulin secretion from the clonal pancreatic beta cell line, BRIN-BD11. In the presence of a stimulatory (8.4 m m) glucose concentration, both KU14R (50-200 microm;P< 0.01 to P< 0.001) and RX801080 (50-200 microm;P< 0.01 to P< 0.001) were found to dose-dependently stimulate insulin secretion. The imidazoline efaroxan (200 microm) stimulated insulin secretion (P< 0.001) from BRIN-BD11 cells. This insulinotropic effect was significantly augmented by KU14R (100-200 microm;P< 0.01 to P< 0.001) and RX801080 (200 microm;P< 0.05). Insulin secretion from BRIN-BD11 cells was also stimulated by the novel guanidine derivative BTS 67 582 (200 microm;P< 0.001). This secretagogue action was augmented both by KU14R (25-200 microm;P< 0.001) and by RX801080 (25-200 microm;P< 0.05 to P< 0.001). It is concluded that, rather than acting as antagonists of imidazoline-induced insulin secretion, the imidazoline derivatives KU14R and RX801080 are themselves potent insulinotropic agents.

Desensitization of sulphonylurea- and nutrient-induced insulin secretion following prolonged treatment with glibenclamide

Functional effects of prolonged exposure to the sulphonylurea glibenclamide were examined in a popular clonal pancreatic beta-cell line, denoted as BRIN-BD11. In acute 20-min incubations, 200 microM of tolbutamide or glibenclamide stimulated insulin release from non-depolarized and depolarized cells, which was dramatically reduced following 18-h culture with 100 microM glibenclamide. Sulphonylurea desensitization in non-depolarized cells was reversed following 6-36-h subsequent culture in the absence of glibenclamide. However, desensitization of insulinotropic effects of sulphonylureas in depolarized cells following glibenclamide culture and associated decline in cellular insulin content was not fully reversible. Culture with 100 microM glibenclamide also markedly reduced the acute insulinotropic actions of glucose, L-alanine, L-arginine, 2-ketoisocaproic acid (KIC) and KCl. These effects were almost completely reversed following 18-h culture in the absence of the sulphonylurea.

Induced desensitization of the insulinotropic effects of antidiabetic drugs, BTS 67 582 and tolbutamide

Acute and chronic mechanisms of action of novel insulinotropic antidiabetic drug, BTS 67 582 (1, 1-dimethyl-2-(2-morpholinophenyl)guanidine fumarate), were examined in the stable cultured BRIN-BD11 cell line. BTS 67 582 (100 - 400 microM) stimulated a concentration-dependent increase (P<0.01) in insulin release at both non-stimulatory (1.1 mM) and stimulatory (8. 4 mM) glucose. Long-term exposure (3 - 18 h) to 100 microM BTS 67 582 in culture time-dependently decreased subsequent responsiveness to acute challenge with 200 microM BTS 67 582 or 200 microM tolbutamide at 12 - 18 h (P<0.001). Similarly 3 - 18 h culture with the sulphonylurea, tolbutamide (100 microM), also effectively suppressed subsequent insulinotropic responses to both BTS 67 582 and tolbutamide. Culture with 100 microM BTS 67 582 or 100 microM tolbutamide did not affect basal insulin secretion, cellular insulin content, or cell viability and exerted no influence on the secretory responsiveness to 200 microM of the imidazoline, efaroxan. While 18 h BTS 67 582 culture did not affect the insulin-releasing actions (P<0.001) of 16.7 mM glucose, 10 mM arginine, 30 mM KCl, 25 microM forskolin or 10 nM phorbol-12-myristate 13-acetate (PMA), significant inhibition (P<0.001) of the insulinotropic effects of 10 mM 2-ketoisocaproic acid (KIC) and 10 mM alanine were observed. These data suggest that BTS 67 582 shares a common signalling pathway to sulphonylurea but not imidazoline drugs. Desensitization of drug action may provide an important approach to dissect sites of action of novel and established insulinotropic antidiabetic agents.

Drug-induced desensitization of insulinotropic actions of sulfonylureas

K(ATP)-channel-dependent and K(ATP)-channel-independent insulin-releasing actions of the sulfonylurea, tolbutamide, were examined in the clonal BRIN-BD11 cell line. Tolbutamide stimulated insulin release at both nonstimulatory (1.1 mM) and stimulatory (16. 7 mM) glucose. Under depolarizing conditions (16.7 mM glucose plus 30 mM KCl) tolbutamide evoked a stepwise K(ATP) channel-independent insulinotropic response. Culture (18 h) with tolbutamide or the guanidine derivative BTS 67 582 (100 microM) markedly reduced (P < 0. 001) subsequent responsiveness to acute challenge with tolbutamide, glibenclamide, and BTS 67 582 but not the imidazoline drug, efaroxan. Conversely, 18 h culture with efaroxan reduced (P < 0.001) subsequent insulinotropic effects of efaroxan but not that of tolbutamide, glibenclamide, or BTS 67 582. Culture (18 h) with tolbutamide reduced the K(ATP) channel-independent actions of both tolbutamide and glibenclamide. Whereas culture with efaroxan exerted no effect on the K(ATP) channel-independent actions of sulfonylureas, BTS 67 582 abolished the response of tolbutamide and inhibited that of glibenclamide. These data demonstrate that prolonged exposure to tolbutamide desensitizes both K(ATP)-channel-dependent and -independent insulin-secretory actions of sulfonylureas, indicating synergistic pathways mediated by common sulfonylurea binding site(s).

Sedation and sedative drugs in paediatrics

The first article in this series looked at the provision of analgesia in paediatric practice. Practical procedures are common in paediatric practice. Certain procedures may be painful or distressing to the child if undertaken in the absence of sedation or analgesia. This article reviews the practical considerations which arise from the use of sedative drugs in children and looks at some of the drugs available.

Analgesia and analgesic drugs in paediatrics

This article reviews the management of acute and chronic pain in childhood. Many of the common problems are discussed and the range of therapeutic options are reviewed, including possible future advances. The management of pain in neonates is not discussed. The second article of this series will describe the use of sedative drugs in paediatric practice.