Sub-millisecond microfluidic mixers coupled to time-resolved in situ photonics to study ultra-fast reaction kinetics: the case of ultra-small gold nanoparticle synthesis

We report a continuous microreactor platform achieving sub-millisecond homogeneous reagent mixing (∼300 μs) for a time-resolved study on the synthesis of ultra-small gold nanoparticles (NPs). The microreactor (coupled with small angle X-ray scattering, UV-vis, and X-ray absorption spectroscopy for in situ and in operando characterizations), operates within mixing time frames below system characteristic times, providing a unique opportunity to deepen the comprehension of reaction and phase transition pathways with unprecedented details. The microreactor channel length can be approximated to a given reaction time when operated in continuous mode and steady state. As a result, the system can be statically investigated, eliminating technique-dependent probing time constraints and local inhomogeneities caused by mixing issues. We have studied Au(0) NP formation kinetics from Au(III) precursors complexed with oleylamine in organic media, using triisopropylsilane as a reducing agent. The existence of Au(III)/Au(I) prenucleation clusters and the formation of a transient Au(I) lamellar phase under certain conditions, before the onset of Au(0) formation, have been observed. Taking advantage of the high frequency time-resolved information, we propose and model two different reaction pathways associated with the presence or absence of the Au(I) lamellar phase. In both cases, non-classical pathways leading to the formation of NPs are discussed.

A survey in the West Midlands of the United Kingdom of current practice in managing hypotension in lower segment caesarean section under spinal anaesthesia

BACKGROUND

Spinal anaesthesia, the most common form of anaesthesia for caesarean section, leads to sympathetic blockade and profound maternal hypotension resulting in adverse maternal and neonatal outcomes. Hypotension, nausea and vomiting remain common but until the publication of the National Institute of Health and Care Excellence (NICE) 2021 guidance, no national guideline existed on how best to manage maternal hypotension following spinal anaesthesia for caesarean section. A 2017 international consensus statement recommended prophylactic vasopressor administration to maintain a systolic blood pressure of >90% of an accurate pre-spinal value, and to avoid a drop to <80% of this value. This survey aimed to assess regional adherence to these recommendations, the presence of local guidelines for management of hypotension during caesarean section under spinal anaesthesia, and the individual clinician's treatment thresholds for maternal hypotension and tachycardia.

METHODS

The West Midlands Trainee-led Research in Anaesthesia and Intensive Care Network co-ordinated surveys of obstetric anaesthetic departments and consultant obstetric anaesthetists across 11 National Health Service Trusts in the Midlands, England.

RESULTS

One-hundred-and-two consultant obstetric anaesthetists returned the survey and 73% of sites had a policy for vasopressor use; 91% used phenylephrine as the first-line drug but a wide range of recommended delivery methods was noted and target blood pressure was only listed in 50% of policies. Significant variation existed in both vasopressor delivery methods and target blood pressures.

CONCLUSIONS

Although NICE has since recommended prophylactic phenylephrine infusion and a target blood pressure, the previous international consensus statement was not adhered to routinely.

Update and Evaluation of a High-Throughput In Vitro Mass Balance Distribution Model: IV-MBM EQP v2.0

This study demonstrates the utility of an updated mass balance model for predicting the distribution of organic chemicals in in vitro test systems (IV-MBM EQP v2.0) and evaluates its performance with empirical data. The IV-MBM EQP v2.0 tool was parameterized and applied to four independent data sets with measured ratios of bulk medium or freely-dissolved to initial nominal concentrations (e.g., C24/C0 where C24 is the measured concentration after 24 h of exposure and C0 is the initial nominal concentration). Model performance varied depending on the data set, chemical properties (e.g., "volatiles" vs. "non-volatiles", neutral vs. ionizable organics), and model assumptions but overall is deemed acceptable. For example, the r² was greater than 0.8 and the mean absolute error (MAE) in the predictions was less than a factor of two for most neutral organics included. Model performance was not as good for the ionizable organic chemicals included but the r² was still greater than 0.7 and the MAE less than a factor of three. The IV-MBM EQP v2.0 model was subsequently applied to several hundred chemicals on Canada's Domestic Substances List (DSL) with nominal effects data (AC50s) reported for two in vitro assays. We report the frequency of chemicals with AC50s corresponding to predicted cell membrane concentrations in the baseline toxicity range (i.e., >20-60 mM) and tabulate the number of chemicals with "volatility issues" (majority of chemical in headspace) and "solubility issues" (freely-dissolved concentration greater than water solubility after distribution). In addition, the predicted "equivalent EQP blood concentrations" (i.e., blood concentration at equilibrium with predicted cellular concentration) were compared to the AC50s as a function of hydrophobicity (log octanol-water partition or distribution ratio). The predicted equivalent EQP blood concentrations exceed the AC50 by up to a factor of 100 depending on hydrophobicity and assay conditions. The implications of using AC50s as direct surrogates for human blood concentrations when estimating the oral equivalent doses using a toxicokinetic model (i.e., reverse dosimetry) are then briefly discussed.

Anticandidal synergistic activity of Ocimum sanctum and fluconazole of azole resistance strains of clinical isolates

Candida albicans is the most prevalent fungal pathogen in humans. It is the causative agent and most associated with serious fungal infection, accounting for more than 90% of cases. It is a most common cause of deep mycoses and vulvovaginal candidiasis. In the present study we found that methanolic extract of O. sanctum in combination of fluconazole shows higher zone of inhibition and lesser MIC values as compared to methanolic extract of leaves of O. sanctum or fluconazole when used alone. Synergistic antimicrobial activity was found when methanolic extract of leaves of O. sanctum was used in combination with fluconazole against C. albicans azole resistance strains isolated from catheter tip (CT) and high vaginal swab (HVS) (FIC≤0.5). Partial synergistic activity was observed against urine (U). Methanolic extract of stem of O. sanctum in combination with fluconazole gave indifferent antifungal results (FIC=1.0-4.0). Benzene extract of the leaf and stem of O. sanctum in combination with fluconazole showed indifferent antifungal results (FIC=1.0-4.0). Aqueous extract of leaves of O. sanctum in combination with fluconazole showed partial synergistic antimicrobial activity against catheter tip (CT) and high vaginal swab (HVS) and urine (U) (FIC=0.5-1.0). In the present study we evaluate the synergism of C. albicans against azole resistant clinical isolates. This study indicates clear evidence supporting the traditional use of O. sanctum in treating Candida infectious diseases.

T cell subsets: an immunological biomarker to predict progression to clinical arthritis in ACPA-positive individuals

Objectives

Anticitrullinated protein antibody (ACPA)+ individuals with non-specific musculoskeletal symptoms are at risk of inflammatory arthritis (IA). This study aims to demonstrate the predictive value of T cell subset quantification for progression towards IA and compare it with previously identified clinical predictors of progression.

Methods

103 ACPA+ individuals without clinical synovitis were observed 3-monthly for 12 months and then as clinically indicated. The end point was the development of IA. Naïve, regulatory T cells (Treg) and inflammation related cells (IRCs) were quantified by flow cytometry. Areas under the ROC curve (AUC) were calculated. Adjusted logistic regressions and Cox proportional hazards models for time to progression to IA were constructed.

Results

Compared with healthy controls (age adjusted where appropriate), ACPA+ individuals demonstrated reduced naïve (22.1% of subjects) and Treg (35.8%) frequencies and elevated IRC (29.5%). Of the 103 subjects, 48(46.6%) progressed. Individually, T cell subsets were weakly predictive (AUC between 0.63 and 0.66), although the presence of 2 T cell abnormalities had high specificity. Three models were compared: model-1 used T cell subsets only, model-2 used previously published clinical parameters, model-3 combined clinical data and T cell data. Model-3 performed the best (AUC 0.79 (95% CI 0.70 to 0.89)) compared with model-1 (0.75 (0.65 to 0.86)) and particularly with model-2 (0.62 (0.54 to 0.76)) demonstrating the added value of T cell subsets. Time to progression differed significantly between high-risk, moderate-risk and low-risk groups from model-3 (p=0.001, median 15.4 months, 25.8 months and 63.4 months, respectively).

Conclusions

T cell subset dysregulation in ACPA+ individuals predates the onset of IA, predicts the risk and faster progression to IA, with added value over previously published clinical predictors of progression.

Delayed developmental immunotoxicity of prenatal benzodiazepines

Treatment of pregnant rats with low doses of classical benzodiazepines (BDZ, e.g. 1.25 mg diazepam/kg body weight) or a peripheral type BDZ receptor (PBR) agonist between gestational days 14 and 20 has been shown to result in a long-lasting depression of cellular and humoral immune responses in the offspring. Considerable alterations in mitogen-stimulated cytokine production in rats exposed to diazepam prenatally have now been observed: TNF-alpha liberation by splenocytes of diazepam-exposed rats was reduced at 2 wk of age and increased above control values at 8 wk, and interleukin (IL)-6 was depressed in the offspring at 2 and 8 wk of age. IL-1 was diminished during post-weaning and adult periods in male offspring but only in adult life in female offspring. In contrast, T-cell derived IL-2 was decreased during the postnatal period and normalized in adulthood. Prostaglandin E(2) (PGE(2)), which is known to down-regulate tumour necrosis factor-alpha (TNF-alpha) was increased and interferon-gamma (IFN-gamma), which stimulates TNF-alpha release, was depressed in 2-wk-old offspring that had been treated prenatally. Release of PGE(2) and IFN-gamma was still altered in young adulthood. While the initial action on the foetal immune system remains unknown, an interaction of the drugs with the PBR is suggested by the effectiveness of the PBR agonist and by altered characteristics of PBR (i.e. a decreased B(max) of [(3)H]PK 11195 binding to macrophage membranes of 8-wk-old offspring and an increased Kd of spleen cell membranes of 2-wk-old offspring).

Evidence that variation at the serotonin transporter gene influences susceptibility to attention deficit hyperactivity disorder (ADHD): analysis and pooled analysis

Reduced central serotonergic activity has been implicated in poor impulse regulation and aggressive behaviour in animals, adults and also young children.(1,2) Two recently published studies have implicated variation at a polymorphism in the promoter of the serotonin transporter (5HTT; hSERT) in influencing susceptibility to ADHD.(3,4) Consistent with these results we have also found a trend for the long allele of the promoter polymorphism to influence susceptibility to ADHD in a sample of 113 ADHD parent proband trios (65 transmissions vs 49 non-transmissions, chi(2) = 2.25, P = 0.13). A pooled analysis of our, and these published results demonstrated a significant over representation of the long allele of the promoter in ADHD probands compared to controls (chi(2) = 7.14, P = 0.008). We have also examined two other 5HTT polymorphisms (the VNTR in intron 2 and the 3' UTR SNP). TDT analysis demonstrated preferential transmission of the T allele of the 3' UTR SNP (chi(2) = 4.06, P = 0.04). In addition, ETDT analysis of haplotypes demonstrated significant preferential transmission of haplotypes containing the T allele of the 3' UTR SNP with the long allele of the promoter polymorphism (chi(2) = 13.18, 3 df, P = 0.004) and the 10 repeat of the VNTR (chi(2) = 8.77, 3 df, P = 0.03). This study provides further evidence for the possible involvement of the serotonin transporter in susceptibility to ADHD.

Recreational ecstasy/MDMA and other drug users from the UK and Italy: psychiatric symptoms and psychobiological problems

RATIONALE

Recreational drug use is increasingly widespread amongst young people, but there are concerns that psychoactive drugs may be associated with psychiatric symptoms or psychobiological problems.

OBJECTIVES

To assess the psychiatric health status of a large, non-clinical sample of young adults from Italy and the UK, and relate it to their use of ecstasy/MDMA and other recreational drugs.

METHODS

The UEL Recreational Drug Use Questionnaire was completed by 768 young people (mean age 21.7 years) from four European cities. The subjects comprised 150 non-drug users, 185 alcohol/tobacco users, 97 cannabis and alcohol/tobacco users, 102 illicit polydrug but not ecstasy users, 115 light (<20 times) ecstasy polydrug users, and 119 heavy (>20 times) ecstasy polydrug users. The unpaid volunteers completed the SCL-90 self-rating inventory for psychiatric symptoms when off drug, with 30 additional questions covering positive moods and life experiences.

RESULTS

Heavy ecstasy polydrug users reported significantly higher scores than non-drug users on several SCL-90 factors, including phobic anxiety, obsessive-compulsive behaviour, anxiety, psychoticism, somatisation, and significantly higher rates of 'loss of sex interest or pleasure'. Self-rated symptom scores increased in line with greater drug use, so that polydrug users who had never taken ecstasy also reported a variety of psychobiological impairments. In contrast, positive moods and life experiences were broadly similar across subgroups.

CONCLUSIONS

The recreational use of ecstasy/MDMA is associated with a range of psychiatric symptoms and psychobiological problems. However, these problems are not specific to ecstasy users but are also evident in other recreational polydrug users.

Novel tocotrienols of rice bran inhibit atherosclerotic lesions in C57BL/6 ApoE-deficient mice

We are studying novel tocotrienols, which have a number of activities that might interfere with the formation of atherosclerotic plaques, including hypocholesterolemic, antioxidant, anti-inflammatory and antiproliferation effects. This study compared the effects of alpha-tocopherol, the tocotrienol-rich fraction (TRF(25)) and didesmethyl tocotrienol (d-P(25)-T3) of rice bran on the pathogenesis of atherosclerotic lesions in C57BL/6 apolipoprotein (apo)E-deficient (-/-) mice. These mice are an excellent model because they become hyperlipidemic even when they consume a low fat diet and they develop complex atherosclerotic lesions similar to those of humans. These compounds were also tested in wild-type C57BL/6 apoE (+/+) and (+/-) mice fed low or high fat diets. When a high fat diet was supplemented with alpha-tocopherol, TRF(25) or d-P(25)-T3 and fed to mice (+/+) for 24 wk, atherosclerotic lesion size was reduced 23% (P = 0.33), 36% (P = 0.14) and 57% (P < 0.02), respectively, and in mice (+/-) fed for 18 wk, lesions were reduced by 19% (P = 0.15), 28% (P < 0.01) and 33% (P < 0.005), respectively, compared with mice fed a control diet. A low fat diet did not cause atherosclerotic lesions in these mice. The low fat diet supplemented with TRF(25) or d-P(25)-T3 fed to apoE-deficient (-/-) mice for 14 wk decreased atherosclerotic lesion size by 42% (P < 0.04) and 47% (P < 0.01), respectively, whereas alpha-tocopherol supplementation resulted in only an 11% (P = 0.62) reduction. These results demonstrate the superior efficacy of tocotrienols compared with alpha-tocopherol. Although tocotrienols decreased serum triglycerides, total and LDL cholesterol levels, the decreases in atherosclerotic lesions seem to be due to the other activities. Serum tocol concentrations in various groups are also described. This is the first report of a significant reduction in the atherosclerotic lesion size in all three genotypes of apoE mice fed a novel tocotrienol (d-P(25)-T3) of rice bran. Dietary tocotrienol supplements may provide a unique approach to promoting cardiovascular health.

Analysis of the mismatch and insertion/deletion binding properties of Thermus thermophilus, HB8, MutS

The methyl-directed long patch repair pathway in Escherichia coli is involved in increasing the fidelity of replication specific repair of DNA polymerase incorporation errors. This pathway is mediated by three gene products, MutS, MutL, and MutH, which are conserved in higher eukaryotes. Mutations in human homologues of these proteins have been shown to be implicated in hereditary non-polyposis colorectal cancer (HNPCC). A MutS homologue has recently been identified in the extremely thermophilic bacterium, Thermus thermophilus. Here we describe analysis of the binding properties of this protein, which has indicated it can identify all specific base mismatches as well as one, two and three base pair insertion/deletion mutations. We therefore believe this protein may be generally useful for applications involving mismatch detection.

Mutational analysis of the nucleotide binding domain of the mismatch repair enzyme hMSH-2

The genes involved in postreplicative DNA mismatch repair are a highly conserved family of proteins. In humans, germline mutations in these genes (hMSH-2, hMLH-1, hPMS-1, and hPMS-2) have been implicated in hereditary nonpolyposis colorectal cancer (HNPCC). We have previously shown that a region of high homology between the members of this class of proteins in different species contains a type A nucleotide binding site consensus sequence which has ATPase activity and is sufficient to bind DNA containing specific mismatched residues (1). To identify residues which are necessary for this activity, we have created a range of mutants containing amino acid substitutions within the nucleotide binding domain of hMSH-2. These mutants have been expressed and assessed for ATPase activity and their ability to identify mismatch-containing DNA. Here we demonstrate that a variant protein which has the conserved residue Lys 675 within the nucleotide binding consensus sequence altered to an alanine has severely impaired ATPase activity and is unable to bind DNA containing specific mismatched residues.

Autism and multiple pituitary deficiency

We describe a 9-year-old boy who presented with abnormal development in language and social interaction. He also showed evidence of stereotyped behaviour, thus fulfilling all the criteria for an ICD-10 diagnosis of autism. This was associated with multiple pituitary deficiency. No case of autism associated with hypopituitarism has hitherto been reported. The authors discuss the evidence for linking the two conditions as opposed to accepting them as coincidental. In some studies of autism, anatomical and imaging studies have provided evidence of pathology in the limbic lobe. This lobe plays an essential role in the modification and expression of emotional reactions. Together with other areas, the limbic system sends outputs from the hypothalamus and from there to the pituitary. Our case illustrates a possible link between emotional expression and hypopituitarism.

Butyrate enema therapy stimulates mucosal repair in experimental colitis in the rat

BACKGROUND

The short chain fatty acid (SCFA) butyrate provides energy for colonocytes, stimulates colonic fluid and electrolyte absorption and is recognised as an effective treatment for multiple types of colitis.

AIM

To examine the impact of butyrate enema therapy on the clinical course, severity of inflammation, and SCFA stimulated Na+ absorption in a chronic experimental colitis.

METHODS

Distal colitis was induced in rats with a trinitrobenzenesulphonic acid (TNBS) enema. Five days after induction, rats were divided into groups to receive: no treatment, saline enemas, or 100 mM Na-butyrate enemas daily. On day 24, colonic damage score and tissue myeloperoxidase (MPO) activity were evaluated. Colon was mounted in Ussing chambers and Na+ transport and electrical activities were measured during a basal period and after stimulation with 25 mM butyrate.

RESULTS

In the untreated and the saline enema treated TNBS groups, diarrhoea and extensive colonic damage were seen, associated with increased tissue MPO activities and absent butyrate stimulated Na+ absorption. In contrast, in the butyrate enema treated TNBS group, diarrhoea ceased, colonic damage score improved, and tissue MPO activity as well as butyrate stimulated Na+ absorption recovered to control values.

CONCLUSION

Butyrate enema therapy stimulated colonic repair, as evidenced by clinical recovery, decreased inflammation, and restoration of SCFA stimulated electrolyte absorption.

Laminar distribution of GABAA receptor alpha 1, beta 2, and gamma 2 subunit mRNAs in the granular and agranular frontal cortex of the rat during pre- and postnatal development

The expression of mRNAs encoding the three GABAA receptor subunits that are associated with the most abundant benzodiazepine-sensitive GABAA receptor in adult cortex, that is, the alpha 1, beta 2, and gamma 2 subunits, was studied in rat cortex during pre- and postnatal development by means of in situ hybridization, gamma 2 and beta 2 mRNAs become detectable in neocortex at gestational day 16 (GD16), alpha 1 at GD18. gamma 2 mRNA exhibits the highest level of expression at early ages, while alpha 1 mRNA levels are low. beta 2 mRNA rises steeply during the last days of gestation. Around birth, it shows the highest expression of the three subunits studied in cortex, and increases further until postnatal day 15 (PD15). The expression of alpha 1 subunit mRNA also increases markedly shortly before birth and accelerates between PD8 and PD15, when it reaches higher levels than the other two subunits. Following the initial high expression, gamma 2 mRNA increases gradually and slowly until PD25. During prenatal development, highest expression of all three subunit mRNAs is found in the upper layers of cortex, that is, cortical plate and marginal zone. The subplate layer does not start to express GABAA receptor subunit mRNAs until GD18. At birth, all developing layers of the cortex express mRNAs for the three subunits, except the marginal zone. Highest levels are found in the upper part of the cortical plate. At the end of the first postnatal week (PD8), the laminar distribution of mRNA expression in neocortex becomes more differentiated. For all three subunit mRNAs, highest expression is then observed in neuron-like cells in layer IV in the granular areas, and over layers III and upper V in agranular areas. Subsequently, between PD8 and PD25, increasing levels of expression are observed over the pyramidal cell layer V. This regionally differentiated, developmental pattern suggests a close relationship between development of GABAA receptor subunits, ingrowth of thalamocortical projections, and maturation of neocortical circuitry.

Prenatal diazepam induced persisting downregulation of peripheral (omega 3) benzodiazepine receptors on rat splenic macrophages

Prenatal treatment with a low dose of diazepam (1.25 mg/kg/d, gestational day 14-20) has previously been found to cause longterm impairment of cellular immune responses in rat offspring. A possible site of action of diazepam, i.e., the peripheral-type (omega 3) benzodiazepine receptor, was characterized on splenic macrophages as well as on a rat splenic cell preparation containing mainly lymphocytes. In membranes of both preparations, [3H]PK 11195 bound to a single site which in competition experiments exhibited characteristics of the (omega 3) site. Prenatal exposure to diazepam was followed, at 8 weeks of life, by a marked decrease in maximal binding capacity (Bmax) of spleen macrophage membranes in offspring of both sexes, while membranes of the splenic cell preparation exhibited an increase of the dissociation constant of [3H]PK 11195 at 2 and 8 weeks of life. Both types of delayed effects may reduce the metabolic capacity of these immune cells, in which we have also observed deficits of cytokine release.

Mechanisms of cytotoxicity caused by antitumour drugs

Although the nature of the interaction between a drug or toxin and its target is of critical importance in determining the fate of a cell, we have argued here that the biological outcome of that interaction will also be determined by the nature of cellular events "downstream" of the initial interactions. We suggest that some type of coupling must take place between the formation of a drug-target interaction (the stimulus?) and the response of the cell. That response will depend upon the phenotypically determined repertoire of response open to the cell as well as upon the quantitative and qualitative measures of the events that the drug induces (DNA or protein damage, inhibition of growth etc.). For example we have described how the HL-60 cell appears to respond to low levels of toxins by engaging a programme of terminal differentiation whilst at greater concentrations apoptosis becomes engaged. Consideration of the cellular response to a toxic insult may provide valuable insights into the selective toxicity of agents as well as providing avenues for the discovery of toxins which might be useful in the treatment of cancer.

Autoreactivity in women with endometriosis

Serum samples from 71 patients with laparoscopically staged endometriosis and from 109 age-matched non-pregnant control women were tested for antibodies to nuclear, phospholipid, smooth muscle and sperm antigens. Immunoglobulin G, M and A and complement components C3 and C4 were measured. Prevalence of the following autoantibodies was statistically significantly greater in women with endometriosis than in the control group: antinuclear antibodies, antibodies to ribonucleoproteins, smooth muscle antibodies, lupus anticoagulant and anticardiolipin antibody. Forty-one women with endometriosis (58%) had some type of autoantibody compared with 13 controls (12%). More women in the endometriosis group had IgG and IgM levels above the normal range. This was statistically significant for IgG in women with grade 3 and for IgM in those with grade 4 endometriosis, IgG levels were significantly higher in antibody-positive women with endometriosis than in the control group. Immunoglobulin and complement component levels tended to have a positive correlation with stage of disease.

Prenatal benzodiazepine immunosuppression: possible involvement of peripheral benzodiazepine site

Treatment of pregnant Long Evans rats with a low dose of diazepam (1.25 mg/kg from gestational day 14-20) produced offspring suffering from suppression of cellular immune responses. Analogous effects were produced by clonazepam, a benzodiazepine (BDZ) with high affinity for the central-type, and Ro 5-4864, a BDZ with selective affinity for the peripheral-type BDZ receptor. Peripheral-type BDZ receptors are found to develop early in fetal life in peripheral organs including primary (thymus) and secondary (spleen) lymphoid organs, in the central nervous system and on immune cells (lymphocytes). In prenatally diazepam-exposed offspring the affinity constant is significantly changed. BDZ and PK 11195 also inhibit mitogen and alloantigen-induced T and B cell proliferation in vitro in adult murine lymphocytes. Diazepam, Ro 5-4864 and PK 11195 were found to be the most active compounds.