Combination of Dasatinib and Quercetin alleviates heat stress-induced cognitive deficits in aged and young adult male mice

OBJECTIVE

Dasatinib and quercetin (D & Q) have demonstrated promise in improving aged-related pathophysiological dysfunctions in humans and mice. Herein we aimed to ascertain whether the heat stress (HS)-induced cognitive deficits in aged or even young adult male mice can be reduced by D & Q therapy.

METHODS

Before the onset of HS, animals were pre-treated with D & Q or placebo for 3 consecutive days every 2 weeks over a 10-week period. Cognitive function, intestinal barrier permeability, and blood-brain barrier permeability were assessed.

RESULTS

Compared to the non-HS young adult male mice, the HS young adult male mice or the aged male mice had significantly lesser extents of the exacerbated stress reactions, intestinal barrier disruption, endotoxemia, systemic inflammation and oxidative stress, blood-brain barrier disruption, hippocampal inflammation and oxidative stress, and cognitive deficits evaluated at 7 days post-HS. All the cognitive deficits and other syndromes that occurred in young adult HS mice or in aged HS mice were significantly attenuated by D & Q therapy (P < 0.01). Compared to the young adult HS mice, the aged HS mice had significantly (P < 0.01) higher severity of cognitive deficits and other related syndromes.

CONCLUSIONS

First, our data show that aged male mice are more vulnerable to HS-induced cognitive deficits than those of the young adult male mice. Second, we demonstrate that a combination of D and Q therapy attenuates cognitive deficits in heat stressed aged or young adult male mice via broad normalization of the brain-gut-endotoxin axis function.

The forensic implications of food hypersensitivity – a review of cases in United Kingdom courts: January 2014–February 2020

Aims:

Food allergy is a major public health concern. Failures of food allergen avoidance and the consequences for those with food hypersensitivity (allergies, intolerances and coeliac disease) have a forensic context. The aim of this study was to collate and analyse the use of action in the United Kingdom (UK) courts as redress following adverse food allergy reactions or failures of allergen management.

Methods:

Details of prosecutions during the study period (1 January 2014 to 31 January 2020) were recorded from regular key word Internet searches. National and local news reports were primary sources, along with commentary from enforcement and regulatory professionals. Information was also collected from coroners’ inquests by attending hearings and direct contact with coroners and participants in the hearings. Freedom of Information requests were made to local authority enforcement departments. In several cases, the authors had direct involvement in investigations.

Results:

From 2014 to 2020, there was an increase in reports. Seventy prosecutions were recorded as well as two associated appeals and two applications for Hygiene Emergency Prohibition Notice. This resulted in 68 convictions; seven individuals received custodial sentences, three of which were suspended although one individual had a tagged curfew imposed. Fines ranged from £50 to £93,000. Details of the law applied and the evidence gathering processes are reported.

Conclusion:

Legal action, including landmark prosecutions for Gross Negligence Manslaughter and Preventing Future Deaths reports from coroners, with salience of criminal penalties, has led to changes in labelling law and improved allergen management practices better to protect the interests of patients with food hypersensitivities. A central system of collation of such data, and on ‘near misses’, will enable more focused root cause analysis to further improve allergen management and reduce patient risk.

Honey authenticity: the opacity of analytical reports-part 2, forensic evaluative reporting as a potential solution

The analytical techniques applied to verify honey authenticity are multifaceted and often result in complex data rich certificates of analysis that are open to interpretation and may be opaque to stakeholders without specialist knowledge. In these cases, the drawing of an independent overarching opinion is challenging. Two questions arise: (Q1) Is it acceptable to report interpretation, particularly if it is adverse, without exhibiting the supporting data? (Q2) How may a valid overarching opinion on authenticity be derived from a large, partially conflicting, dataset? To Q1, it is demonstrated that full disclosure of the data used in interpretation is mandatory. To Q2 it is proposed, with worked examples, to adopt ‘evaluative reporting’; a formalised likelihood ratio thought process used in forensic science for evaluation of findings and their strength assessment. In the absence of consensus on techniques for honey authenticity adoption of reporting conventions will allow objective assessments of reports, with equity to all and provide a better basis to identify and address fraud.

The impact of the COVID-19 pandemic on the Ontario Cervical Screening Program, colposcopy and treatment services in Ontario, Canada: a population-based study

Objective

To describe the immediate impact of the COVID‐19 pandemic on cervical screening, colposcopy and treatment volumes in Ontario, Canada.

Design

Population‐based retrospective observational study.

Setting

Ontario, Canada.

Population

People with a cervix age of 21–69 years who completed at least one cervical screening cytology test, colposcopy or treatment procedure for cervical dysplasia between January 2019 and August 2020.

Methods

Administrative databases were used to compare cervical screening cytology, colposcopy and treatment procedure volumes before (historical comparator) and during the first 6 months of the COVID‐19 pandemic (March–August 2020).

Main outcome measures

Changes in cervical screening cytology, colposcopy and treatment volumes; individuals with high‐grade cytology awaiting colposcopy.

Results

During the first 6 months of the COVID‐19 pandemic, the monthly average number of cervical screening cytology tests, colposcopies and treatments decreased by 63.8% (range: −92.3 to −41.0%), 39.7% (range: −75.1 to −14.3%) and 31.1% (range: −43.5 to −23.6%), respectively, when compared with the corresponding months in 2019. Between March and August 2020, on average 292 (−51.0%) fewer high‐grade cytological abnormalities were detected through screening each month. As of August 2020, 1159 (29.2%) individuals with high‐grade screening cytology were awaiting follow‐up colposcopy.

Conclusions

The COVID‐19 pandemic has had a substantial impact on key cervical screening and follow‐up services in Ontario. As the pandemic continues, ongoing monitoring of service utilisation to inform system response and recovery is required. Future efforts to understand the impact of COVID‐19‐related disruptions on cervical cancer outcomes will be needed.

Tweetable abstract

COVID‐19 has had a substantial impact on cervical screening and follow‐up services in Ontario, Canada.

COVID‐19 has had a substantial impact on cervical screening and follow‐up services in Ontario, Canada.

Melatonin ameliorates spatial memory and motor deficits via preserving the integrity of cortical and hippocampal dendritic spine morphology in mice with neurotrauma

We aimed to elucidate the role of cortical and hippocampal dendritic spines on neurological deficits associated with hippocampal microgliosis, hippocampal neurogenesis, and neuroinflammation in mice with cortical compact impact (CCI) injury. In the present study, we found that CCI reduced spatial memory mean latency (10 s. vs 50 s) and motor dysfunction (130 s. vs 150 s.) in mice, as determined by Morris water maze and rotarod test, respectively. Golgi staining of cortical pyramidal neurons revealed that, compared to the controls, the CCI group treated with vehicle solution had significantly lower values of dendritic order (or dendritic branch number) (4.0 vs 6.2), total spine length (400 μm vs 620 μm) and spine density (40 spines/μm vs 60 spines/μm), but had significantly higher values of dendritic beading (40 beadings/mm vs 20 beadings/mm). Additionally, Sholl analysis showed that, compared to controls, the CCI + NS group mice had significantly lower values of dendritic intersections (1.0 vs 2.0). Immunofluorescence assay also revealed that, compared to controls, the CCI + NS group mice had significantly higher values of the newly formed hippocampal cells (1250/mm² vs 1000/mm²) but significantly lower values of dendritic order (2.0 branch # vs 4.2 branch #), total spine length (180 μm vs 320 μm) and intersection (1.0 vs 3.0). The CCI + NS group mice further showed significantly higher numbers of microglia in the dentate gyrus of the hippocampus and higher concentrations of pro-inflammatory cytokines in the cerebrospinal fluids. All the CCI-induced spatial memory (40 s) and motor (150 s) dysfunction, deranged dendritic and spine morphology of cortical pyramidal neurons or hippocampal newly formed cells, hippocampal microgliosis, and central neuroinflammation were all significantly reduced by melatonin administration during post-CCI. Simultaneously, melatonin therapy caused an enhancement in the compensatory hippocampal neurogenesis and neurotrophic growth factors (e.g., doublecortin-1) and compensatory central anti-inflammatory cytokines. Our results indicate that melatonin attenuates the spatial memory and motor deficits via the modification of cortical and hippocampal dendritic spine morphology, hippocampal microgliosis and neurogenesis, and neuroinflammation in mice with traumatic brain injury.

Myricetin against myocardial injury in rat heat stroke model

BACKGROUND

Heat stroke-induced mortality is rising across the globe. So, the design of prophylactic and/or therapeutic modalities for heat stroke is pressing need. The common plant derived flavonoid exhibits strong anti-oxidant and anti-inflammatory activities; however, its effects in heat stroke remain unknown. The study aimed to investigate the cardioprotective effects of myricetin on heat stroke induced acute myocardial injury as well as lethality in rats and to explore the underlying mechanisms.

METHODS

Myocardial injury was induced by subjecting the anesthetized rats to a high ambient temperature of 43 °C for 70 min. An intragastrical dose of myricetin (5-25 mg/kg body weight) was given to rats once per day for one week prior to the start of heat stress. Heat shock protein 72 antibodies was given intraperitoneally to rats 24 h before the start of heat stress. Myocardial injury severity was estimated by determing myocardial damage scores, myocardial injury indicators, myocardial oxidative and inflammatory factors. Western blot analysis was used for cardiac expression of heat shock protein (HSP)72.

RESULTS

Significant (P < 0.05) up-regulation of HSP-72 after chronic administration of myricetin coincided with significant (P < 0.05) reduction in hyperthermia, hypotension, cardiac inflammatory and oxidative damage and lethality. Inhibition of HSP-72 showed a significant (P < 0.05) reversal in the cardiaprotection as well as survival.

CONCLUSIONS

Our results indicate that myricetin diminishes myocardial injury as well as lethality in heat stroke by up-regulating HSP-72 and show promise as a novel prevention therapeutic for heat stroke.

Updated emm-typing protocol for Streptococcus pyogenes

OBJECTIVES

PCR-based typing of the emm gene Streptococcus pyogenes often results in the amplification of multiple bands. This has resulted in the misclassification of strains into types based on non-emm gene sequences. We aimed to improve the specificity of the emm typing PCR reaction using a primer called CDC3, the sequence for which has been previously used to identify emm genes in silico.

METHODS

The proposed primer CDC3 was validated in silico from a global database of 1688 GAS genomes and in vitro with 32 isolates. PCR reactions were performed on genomic DNA from each isolate, using the published CDC1 forward primer with the CDC2 reverse primer or the new CDC3 reverse primer. The products were examined by gel electrophoresis, and representative PCR products were sequenced.

RESULTS

In 1688 S. pyogenes genomes, the previous CDC2 reverse primer annealed in silico in 1671 emm genes and also in 2109 non emm genes in close proximity, whereas the new CDC3 primer annealed in 1669 emm genes only. The remaining 19 genes without a CDC3 binding site were chimeric emm genes. The PCR pair CDC1+CDC3 produced a single band at appropriate molecular weight in all 32 isolates tested, while the CDC1+CDC2 pair produced more than one band in 13 of 32 isolates (40%).

CONCLUSIONS

The new CDC3 primer is more specific for emm genes than the previous CDC2 primer and represents a simple solution to reduce the potential for mistyping S. pyogenes strains.

P680The clinical value of CMR in the management of Cardio-Oncology patients - a tertiary centre experience

Background

There is increasing awareness of cardiotoxicity arising from cancer treatments. Early diagnosis and treatment is key, to ensure patients receive optimal oncological management. Cardiovascular magnetic resonance (CMR) offers gold standard measurement of cardiac function, alongside tissue characterisation and myocardial perfusion, thereby potentially providing additive value in the context of cardio-oncology.

Purpose

We sought to understand the clinical value of CMR in cardio-oncology at a tertiary cardio-oncology centre.

Methods

We retrospectively reviewed CMR scans requested in cardio-oncology patients at our institution within a ten-month period. We categorised clinical indications and assessed the impact on clinical management using previously-published criteria.

Results

102 CMR studies were requested in 93 cardio-oncology patients (mean age 56 (range 18 to 82), 49% male) between (March to December 2018). 41% of patients had haematological malignancies, 59% solid tumours.

15% of requests were for risk stratification prior to initiation of cancer therapy, 21% for screening for cardio-toxicity in patients currently receiving cardiotoxic agents (3% anthracyclines, 13% HER2 monoclonal antibodies, 4% fluoropyrimidines), 15% for investigation of patients with cardiac complications during cancer treatment, 35% assessment for late effects post cancer treatment, and 14% for cardiac malignancies/ infiltration.

The most common indications for CMR were monitoring of left ventricular ejection fraction (LVEF) in patients where quantification by echocardiography was non-diagnostic or significantly different between imaging studies (39%) and ischaemia assessment including for patients due to receive fluoropyrimidines (26%). Others were aetiology of LV dysfunction/cardiomyopathy (13%) and tissue characterisation (23%), including assessment for cardiac AL amyloid (11 patients), myocarditis (2), cardiac metastases (1), cardiac masses (6), and cardiac iron loading (1).

CMR findings had clinical impact in 61% of patients and assisted in adjudicating a new diagnosis in 29% of patients. 88% of patients were able to continue anthracycline/anti-HER2 therapies based on CMR findings of stable LVEF (93% of whose echocardiograms had suggested reductions). LVEF had reduced significantly in 12% of patients meaning chemotherapy was held/discontinued. 3 patients were recommended to receive non-fluoropyrimidine chemotherapy based on perfusion CMR (pCMR) findings, with one patient permitted to receive capecitabine following normal pCMR.

Conclusion

CMR provides a comprehensive assessment of myocardial structure and function with utility within the context of cardio-oncology for risk stratification pre-chemotherapy, screening for cardiotoxicity during treatment and investigation of cardiac complications of cancer treatment. The additional information derived from CMR generally provides reassurance enabling administration of optimal cancer therapies.

Précising definitions as a way to combat overdiagnosis

Roughly, overdiagnosis (ODx) occurs when people are harmed by receiving diagnoses (often accompanied by interventions) that do not benefit them, usually because the diagnosed conditions do not pose a threat to their health. ODx is a theoretical as well as a practical problem as it relates to definitions of disease. Elsewhere, it has been argued that disease is a vague concept and that this vagueness may contribute to ODx. In response, we develop a stipulative or précising definition of disease, for the specific purpose of decreasing or preventing ODx. We call this disease_ODx , aimed at distinguishing cases where it would be beneficial to identify (and treat the condition) from those where diagnosis is more likely to harm than benefit. A preliminary definition of disease_ODx is that X is a disease_ODx iff there is dysfunction that has a significant risk of causing severe harm. This paper examines the 3 concepts in this definition, using a naturalistic account of function, a Feinbergian account of comparative harm, and a probabilistic understanding of risk. We then test the utility of this approach using examples of clinical conditions that are currently overdiagnosed.

Fragility, uncertainty, and healthcare

Medicine seeks to overcome one of the most fundamental fragilities of being human, the fragility of good health. No matter how robust our current state of health, we are inevitably susceptible to future illness and disease, while current disease serves to remind us of various frailties inherent in the human condition. This article examines the relationship between fragility and uncertainty with regard to health, and argues that there are reasons to accept rather than deny at least some forms of uncertainty. In situations of current ill health, both patients and doctors seek to manage this fragility through diagnoses that explain suffering and provide some certainty about prognosis as well as treatment. However, both diagnosis and prognosis are inevitably uncertain to some degree, leading to questions about how much uncertainty health professionals should disclose, and how to manage when diagnosis is elusive, leaving patients in uncertainty. We argue that patients can benefit when they are able to acknowledge, and appropriately accept, some uncertainty. Healthy people may seek to protect the fragility of their good health by undertaking preventative measures including various tests and screenings. However, these attempts to secure oneself against the onset of biological fragility can cause harm by creating rather than eliminating uncertainty. Finally, we argue that there are good reasons for accepting the fragility of health, along with the associated uncertainties.

A caspase-3 'death-switch' in colorectal cancer cells for induced and synchronous tumor apoptosis in vitro and in vivo facilitates the development of minimally invasive cell death biomarkers

Novel anticancer drugs targeting key apoptosis regulators have been developed and are undergoing clinical trials. Pharmacodynamic biomarkers to define the optimum dose of drug that provokes tumor apoptosis are in demand; acquisition of longitudinal tumor biopsies is a significant challenge and minimally invasive biomarkers are required. Considering this, we have developed and validated a preclinical 'death-switch' model for the discovery of secreted biomarkers of tumour apoptosis using in vitro proteomics and in vivo evaluation of the novel imaging probe [(18)F]ML-10 for non-invasive detection of apoptosis using positron emission tomography (PET). The 'death-switch' is a constitutively active mutant caspase-3 that is robustly induced by doxycycline to drive synchronous apoptosis in human colorectal cancer cells in vitro or grown as tumor xenografts. Death-switch induction caused caspase-dependent apoptosis between 3 and 24 hours in vitro and regression of 'death-switched' xenografts occurred within 24 h correlating with the percentage of apoptotic cells in tumor and levels of an established cell death biomarker (cleaved cytokeratin-18) in the blood. We sought to define secreted biomarkers of tumor apoptosis from cultured cells using Discovery Isobaric Tag proteomics, which may provide candidates to validate in blood. Early after caspase-3 activation, levels of normally secreted proteins were decreased (e.g. Gelsolin and Midkine) and proteins including CD44 and High Mobility Group protein B1 (HMGB1) that were released into cell culture media in vitro were also identified in the bloodstream of mice bearing death-switched tumors. We also exemplify the utility of the death-switch model for the validation of apoptotic imaging probes using [(18)F]ML-10, a PET tracer currently in clinical trials. Results showed increased tracer uptake of [(18)F]ML-10 in tumours undergoing apoptosis, compared with matched tumour controls imaged in the same animal. Overall, the death-switch model represents a robust and versatile tool for the discovery and validation of apoptosis biomarkers.

Dose and image quality comparison between prospectively gated axial and retrospectively gated helical coronary CT angiography

OBJECTIVE

Our aim was to compare image quality, coronary segment assessability and radiation dose in prospectively gated axial (PGA) coronary CT angiography (CTA) and conventional retrospectively gated helical (RGH) coronary CTA.

METHODS

Institutional review committee approval and informed consent were obtained. RGH CTA was performed in 41 consecutive patients (33 males, 8 females; mean age 52.6 years), then the PGA CTA technique was evaluated in 41 additional patients (24 males, 17 females; mean age 57.3 years) all with a pre-scan heart rate of ≤70 beats per minute (bpm). Two radiologists, blinded to clinical information, independently scored subjective image quality on a five-point ordinal scale.

RESULTS

The mean effective dose in the PGA group was 4.7±0.9 mSv, representing a 69% dose reduction compared with the RGH CTA group (15.1±1.9 mSv, p<0.001). The mean segmental image quality score was significantly higher in the PGA group (3.4 vs 3.2) than in the RGH CTA group (p<0.005). The percentage of assessable segments was 98.1% in the PGA group and 97.3% in the RGH group (p = 0.610).

CONCLUSION

PGA CTA offers a significant reduction in radiation dose compared with RGH CTA, with comparable image quality for patients with heart rates below 70 bpm.

Use of within-group designs to test anti-tussive drugs in conscious guinea-pigs

INTRODUCTION

Cough is a common medical problem for which there are few effective drug treatments. A limited understanding of the mechanisms of induction and maintenance of cough and a paucity of suitable animal models frustrate drug discovery efforts to find novel anti-tussives. As in humans, guinea-pigs evoke a cough reflex upon exposure to tussive agents such as citric acid and capsaicin; both of which have been widely used to assess novel anti-tussive drugs. However, the potential for using within-group designs in drug development has received little attention and such designs may offer a way of assisting the drug discovery effort in the area of cough as well as other areas.

METHODS

Cough can be monitored in conscious guinea-pigs by placing animals in a Perspex chamber, in which air is continually exchanged by use of negative pressure and drug delivery of aerosols to the chamber can be accurately timed. Cough in response to a tussive agent (e.g. 0.2-0.4M citric acid; 10-30 microM capsaicin) is detected by the simultaneous microphonic recording of audible signals characteristic of the cough response as well as by positive pressure changes in the chamber generated by a cough dependent rapid expiration of air from the lungs. Both the sound and pressure signals are recorded using an online analyzer, whilst the number of coughs can be analyzed off-line. The number of coughs over a 15 min period is used to quantitate tussive events.

RESULTS

Reproducible cough can be detected in animals using cross-over designs that lend themselves to drug studies. Both the time and concentration dependence of anti-tussive drug action can be evaluated in the same animal. Furthermore, the effect of different anti-tussive drugs can be evaluated thereby reducing between group error and thereby improving the sensitivity of the test.

DISCUSSION

Repeated measures design improves the precision with which to evaluate anti-tussive drugs in preclinical models and could be used to make the drug discovery process more efficient.

M protein-mediated plasminogen binding is essential for the virulence of an invasive Streptococcus pyogenes isolate

The human protease plasmin plays a crucial role in the capacity of the group A streptococcus (GAS; Streptococcus pyogenes) to initiate invasive disease. The GAS strain NS88.2 was isolated from a case of bacteremia from the Northern Territory of Australia, a region with high rates of GAS invasive disease. Mutagenesis of the NS88.2 plasminogen binding M protein Prp was undertaken to examine the contribution of plasminogen binding and cell surface plasmin acquisition to virulence. The isogenic mutant NS88.2prp was engineered whereby four amino acid residues critical for plasminogen binding were converted to alanine codons in the GAS genome sequence. The mutated residues were reverse complemented to the wild-type sequence to construct GAS strain NS88.2prpRC. In comparison to NS88.2 and NS88.2prpRC, the NS88.2prp mutant exhibited significantly reduced ability to bind human plasminogen and accumulate cell surface plasmin activity during growth in human plasma. Utilizing a humanized plasminogen mouse model of invasive infection, we demonstrate that the capacity to bind plasminogen and accumulate surface plasmin activity plays an essential role in GAS virulence.

Water potential changes in faecal matter and Escherichia coli survival

AIMS

This study investigated the influence of a range of evaporation rates (2.0, 5.3 and 7.4 mm day(-1)) on degradation of E. coli (ATCC Strain 25922) inoculated in canine faeces.

METHODS AND RESULTS

Experiments were carried out in an environmental chamber and a first order exponential decay function (Chick's Law) was used to estimate degradation rates. We estimated die-off coefficients using linear regression. Die-off rates were -0.07, -0.22 and -0.23 h(-1), respectively, for evaporation rates of 2.0, 5.3 and 7.4 mm day(-1) (P = 0.000+, for each model). Nearly complete die-off was found within 15-60 h (7.4-2.0 mm day(-1) evaporation rates), which corresponds with a water potential of approximately -22.4 MPa.

CONCLUSIONS

This study indicates that canine faeces need not be desiccated to achieve complete loss of indicator organisms. Water potential, which is a combination of osmotic and matric potential, is a key stress that increases as evaporation removes water from the faecal matrix and increases concentration of the remaining faecal solution. Evaporation may remove populations of indicator organisms in faeces relatively quickly, even though faeces are not completely dehydrated.

SIGNIFICANCE AND IMPACT OF THE STUDY

This research may be used as the foundation for studies more closely resembling real-world evaporation conditions including diurnal fluctuations, rewetting and freezing.

Trends in candidemia and antifungal susceptibility in a university hospital in Northern Ireland 2001-2006

OBJECTIVES

To describe the species distribution and antifungal susceptibility trends for documented episodes of candidemia at the Royal Hospitals, Belfast, 2001-2006.

METHODS

Laboratory-based retrospective observational study of all episodes of candidemia.

RESULTS

There were 151 episodes of candidemia. The species recovered were: 96 C. albicans; 26 C. glabrata; 18 C. parapsilosis; five C. tropicalis; four C. guilliermondii; one C. famata and one C. dubliniensis. We separated the data into two periods 2001-2003 and 2004-2006; contrary to the findings of other investigators, there was a notable trends toward increasing frequency of C. albicans and decreasing frequency of non-albicans species over time. Although the proportion of C. albicans, C. parapsilosis and C. tropicalis isolates susceptible to fluconazole was unchanged over time, a trend of decreased susceptibility of C. glabrata to fluconazole was noted over the six-year period. Overall, 73% and 7.7% of C. glabrata isolates had susceptible-dose-dependent and resistant phenotypes, respectively. The percentage of C. glabrata isolates susceptible to fluconazole (MIC <8 microg/ml) decreased from 36% in 2001-2003 to 0% in 2004-2006. Flucytosine resistance was detected in only 4 (2.7%) isolates. None of the isolates had an amphotericin B MIC <1 microg/ml.

CONCLUSION

A shift towards increasing dominance of C. albicans contrasts both with reports from other countries and previous data from Northern Ireland. Upwards fluconazole MIC drift among C. glabrata has important implications for empirical therapeutic decisions.

Thyroid hormone insufficiency during brain development reduces parvalbumin immunoreactivity and inhibitory function in the hippocampus

Thyroid hormones are necessary for brain development. gamma-Amino-butyric acid (GABA)ergic interneurons comprise the bulk of local inhibitory circuitry in brain, many of which contain the calcium binding protein, parvalbumin (PV). A previous report indicated that severe postnatal hypothyroidism reduces PV immunoreactivity (IR) in rat neocortex. We examined PV-IR and GABA-mediated synaptic inhibition in the hippocampus of rats deprived of thyroid hormone from gestational d 6 until weaning on postnatal d 30. Pregnant dams were exposed to propylthiouracil (0, 3, 10 ppm) via the drinking water, which decreased maternal serum T(4) by approximately 50-75% and increased TSH. At weaning, T(4) was reduced by approximately 70% in offspring in the low-dose group and fell below detectable levels in high-dose animals. PV-IR was diminished in the hippocampus and neocortex of offspring killed on postnatal d 21, an effect that could be reversed by postnatal administration of T(4). Dose-dependent decreases in the density of PV-IR neurons were observed in neocortex and hippocampus, with the dentate gyrus showing the most severe reductions (50-75% below control counts). Altered staining persisted to adulthood despite the return of thyroid hormones to control levels. Developmental cross-fostering and adult-onset deprivation studies revealed that early postnatal hormone insufficiency was required for an alteration in PV-IR. Synaptic inhibition of the perforant path-dentate gyrus synapse evaluated in adult offspring, in vivo, revealed dose-dependent reductions in paired pulse depression indicative of a suppression of GABA-mediated inhibition. These data demonstrate that moderate degrees of thyroid hormone insufficiency during the early postnatal period permanently alters interneuron expression of PV and compromises inhibitory function in the hippocampus.

Frequency and distribution of group I intron genotypes of Candida albicans colonising critically ill patients

A study is performed to examine the distribution and frequency of 25S rRNA intron genotypes of Candida albicans isolated from different anatomical sites of patients in an intensive care unit (ICU) setting. Germ-tube positive Candida isolates (n=65) from 65 patients are included and isolates are characterised by 25S intron genotyping, whereby all can be subdivided into four genotypes (A-D). Results demonstrated that there were no significant differences between the frequency and genotype distribution of the Candida isolates and the anatomical site of colonisation. Furthermore, analysis of the transposable intron region in the 25S rRNA gene demonstrated equal distribution, regardless of age and anatomical site of isolation (groin, throat, etc.). Therefore, there does not appear to be any selective pressure associated with any anatomical site, resulting in an ecological shift in the frequency of genotypes present. This suggests that C. albicans intron genotypes equally colonise those sites of the body examined in this study. Although such an ecological finding as this is interesting, it perpetuates the continued need to find a genotypic typing scheme that helps to identify the source (nosocomial or endogenous) and mode of entry of C. albicans into patients in the ICU setting, resulting in C. albicans bloodstream infection.

Food allergy: gambling your life on a take-away meal

This study investigates whether or not it is possible to buy meals suitable for peanut allergy sufferers and assesses the training and guidance needs of catering staff and Environmental Health Officers (EHOs) in Northern Ireland with respect to serious food allergies. Meal samples purchased in food premises in the local authority regions of Northern Ireland (NI) were subjected to chemical analysis to check the assertions of the premises staff that they were suitable for peanut allergy sufferers. Officers also assessed if the customer was provided with any information on the allergenic status of foods produced by the establishment; if the EHOs taking the samples had received any training or guidance in allergy-related issues and to gauge the need for such training and guidance. Approximately one in five (13/62) of the premises provided meals which could possibly have triggered a fatal reaction in the purchaser. Most front of house staff did not check the allergen status of the meal with those doing the cooking and most EHOs felt that they needed more training in the subject of food allergen control in commercial food premises. It is important for food allergy sufferers and their medical advisers to be made aware of the limitations of avoidance advice and that false assurances persist of the absence of peanut protein in takeaway foods.

Intranasal vaccination with streptococcal fibronectin binding protein Sfb1 fails to prevent growth and dissemination of Streptococcus pyogenes in a murine skin infection model

Fibronectin binding protein F1 (Sfb1) of Streptococcus pyogenes (group A streptococcus [GAS]) is a well-characterized adhesin that has been shown to induce protection in mice against a lethal intranasal GAS challenge after intranasal immunization with cholera toxin B subunit (CTB) as adjuvant. With a murine skin infection model, we have shown that Sfb1/CTB vaccination neither elicits opsonizing antibodies nor prevents systemic bacterial growth and dissemination to internal organs after a subcutaneous GAS challenge. These results indicate that an Sfb1-based vaccine should be complemented with additional protective antigens in order to be used in areas such as the tropical north of Australia, where the skin is the primary route of entry for invasive streptococcal diseases.

Two distinct genotypes of prtF2, encoding a fibronectin binding protein, and evolution of the gene family in Streptococcus pyogenes

The group A Streptococcus (GAS) is an important pathogen that is responsible for a wide range of human diseases. Fibronectin binding proteins (FBPs) play an important role in promoting GAS adherence and invasion of host cells. The prtF2 gene encodes an FBP and is present in approximately 60% of GAS strains. In the present study we examined 51 prtF2-positive GAS strains isolated from the Northern Territory of Australia, and here we describe two genotypes of prtF2 which are mutually exclusive. The two genotypes have been identified previously as pfbp and fbaB. We show that these genotypes map to the same chromosomal location within the highly recombinatorial fibronectin-collagen-T antigen (FCT) locus, indicating that they arose from a common ancestor, and in this study these genotypes were designated the pfbp type and the fbaB type. Phylogenetic analysis of seven pfbp types, 14 fbaB types, and 11 prtF2-negative GAS strains by pulsed-field gel electrophoresis (PFGE) produced 32 distinct PFGE patterns. Interpretation of evolution based on the PFGE dendrogram by parsimony suggested that the pfbp type had a recent origin compared to the fbaB type. A comparison of multiple DNA sequences of the pfbp and fbaB types revealed a mosaic pattern for the amino-terminal region of the pfbp types. The fbaB type is generally conserved at the amino terminus but varies in the number of fibronectin binding repeats in the carboxy terminus. Our data also suggest that there is a possible association of the pfbp genotype with sof (84.2%), while the fbaB genotype was found in a majority of the GAS strains negative for sof (90.6%), indicating that these two prtF2 subtypes may be under different selective pressures.

Immune responses of a liposome/ISCOM vaccine adjuvant against streptococcal fibronectin binding protein 1 (Sfb1) in mice

BACKGROUND & OBJECTIVES

The fibronectin binding protein Sfb1 of Streptococcus pyogenes is a well characterised antigen which induces protection against lethal challenge with group A streptococcus (GAS) when adjuvanted with cholera toxin B-subunit (CTB). As an alternative to CTB adjuvanted intranasal immunisations we investigated the immune responses generated in mice using Sfb1 incorporated in to the skin and mucosal adjuvant SAMA4.

METHODS

Mice (BALB/c) were vaccinated intradermally with 100 microl of either SAMA4 (adjuvant only group) or SAMA4/Sfb1 and were boosted 7 days later. Mice vaccinated with CTB based vaccines were immunised by intranasal inoculation with a mixture containing 30 microg Sfb1 and 10 microg CTB on days 1, 3, 5 and 15. At 14 days after the last booster immunisation the immune response was characterised and mice were challenged with 10(8) CFU of S. pyogenes.

RESULTS

Mice vaccinated with SAMA4/Sfb1 elicited a Sfb1-specific IgG response in the sera that was significantly higher than that seen in control mice and mice immunised with the adjuvant only (P<0.05). No significant differences were seen for specific IgA antibodies in the sera in all groups examined. Compared with non-immunised and adjuvant only immunised controls, mice immunised with the Sfb1/SAMA4 vaccine exhibited a significant increase (P<0.05) in the number of Sfb1 reactive spleen cells in lymphoproliferation assays which were three fold higher than those seen for mice vaccinated with the Sfb1/CTB vaccine. Mice vaccinated with CTB/Sfb1 had the highest level of protection (80%) as where mice vaccinated with SAMA4 and SAMA4/Sfb1 displayed no protection (20% and 40%).

INTERPRETATION & CONCLUSION

These data suggest that the SAMA4 adjuvant used in this study fails to elicit protective immunity in BALB/c mice when used to adjuvant the known protective antigen Sfb1.

Invertebrate responses to the management of genetically modified herbicide-tolerant and conventional spring crops. II. Within-field epigeal and aerial arthropods

The effects of the management of genetically modified herbicide-tolerant (GMHT) crops on the abundances of aerial and epigeal arthropods were assessed in 66 beet, 68 maize and 67 spring oilseed rape sites as part of the Farm Scale Evaluations of GMHT crops. Most higher taxa were insensitive to differences between GMHT and conventional weed management, but significant effects were found on the abundance of at least one group within each taxon studied. Numbers of butterflies in beet and spring oilseed rape and of Heteroptera and bees in beet were smaller under the relevant GMHT crop management, whereas the abundance of Collembola was consistently greater in all GMHT crops. Generally, these effects were specific to each crop type, reflected the phenology and ecology of the arthropod taxa, were indirect and related to herbicide management. These results apply generally to agriculture across Britain, and could be used in mathematical models to predict the possible long-term effects of the widespread adoption of GMHT technology. The results for bees and butterflies relate to foraging preferences and might or might not translate into effects on population densities, depending on whether adoption leads to forage reductions over large areas. These species, and the detritivore Collembola, may be useful indicator species for future studies of GMHT management.

Invertebrate responses to the management of genetically modified herbicide-tolerant and conventional spring crops. I. Soil-surface-active invertebrates

The effects of herbicide management of genetically modified herbicide-tolerant (GMHT) beet, maize and spring oilseed rape on the abundance and diversity of soil-surface-active invertebrates were assessed. Most effects did not differ between years, environmental zones or initial seedbanks or between sugar and fodder beet. This suggests that the results may be treated as generally applicable to agricultural situations throughout the UK for these crops. The direction of the effects was evenly balanced between increases and decreases in counts in the GMHT compared with the conventional treatment. Most effects involving a greater capture in the GMHT treatments occurred in maize, whereas most effects involving a smaller capture were in beet and spring oilseed rape. Differences between GMHT and conventional crop herbicide management had a significant effect on the capture of most surface-active invertebrate species and higher taxa tested in at least one crop, and these differences reflected the phenology and ecology of the invertebrates. Counts of carabids that feed on weed seeds were smaller in GMHT beet and spring oilseed rape but larger in GMHT maize. In contrast, collembolan detritivore counts were significantly larger under GMHT crop management.

Genotypic subgrouping of clinical isolates of Candida albicans and Candida dubliniensis by 25S intron analysis

AIMS

To determine the frequency, distribution and association of genotypes of Candida albicans and C. dubliniensis in invasive and noninvasive clinical isolates.

METHODS

Twenty-one invasive and 18 noninvasive isolates were examined by PCR amplification of a transposable intron region in the 25S rRNA gene. Isolates were genotyped following analysis of the size of resulting DNA amplicons. The isolates could be subdivided into four genotypes (A-D).

RESULTS

There was no significant difference between the frequency and genotype distribution of the invasive and noninvasive Candida isolates.

IMPACT OF THE STUDY

Therapeutic prophylaxis against candidal infections remains an area of controversy. Any diagnostic markers that reflect the potential of isolates to become invasive should be fully explored, so that more focused antifungal intervention should be targeted at these patients with these potential invasive markers. This study demonstrated that analysis of the transposable intron region in the 25S rRNA gene may be useful in helping to differentiate C. albicans from C. dubliniensis isolates, without the need for sequence analysis, which may not be readily available at primary diagnostic laboratories. However, employment of this genotypic assay is not a suitable locus to determine invasiveness and other more reliable markers of invasiveness should be sought.

Comparison of API20C with molecular identification of Candida spp isolated from bloodstream infections

A study was carried out to compare the API20C technology with polymerase chain reaction amplification and direct sequencing of the short internal transcribed spacer region 2 (ITS2) for the identification of 58 isolates of invasive candida species obtained from patients with bloodstream infections over the seven year period 1994 to 2000. Overall, there was only one disagreement between the phenotypic and genotypic identification, where the API scheme identified the isolate as C albicans but the molecular method identified it as C dubliniensis. This study demonstrated that the API20C method is useful in the identification of Candida spp isolated from blood culture and that molecular methods do not enhance identifications made using the API20C scheme. However, for correct reporting of C dubliniensis, an emerging bloodborne pathogen, it is recommended that all isolates identified as C albicans by the API20C scheme are further examined phenotypically and/or genotypically.

Streptococcus pyogenes prtFII, but not sfbI, sfbII or fbp54, is represented more frequently among invasive-disease isolates of tropical Australia

Streptococcus pyogenes (group A streptococcus) strains may express several distinct fibronectin-binding proteins (FBPs) which are considered as major streptococcal adhesins. Of the FBPs, SfbI was shown in vitro to promote internalization of the bacterium into host cells and has been implicated in persistence. In the tropical Northern Territory, where group 4 streptococcal infection is common, multiple genotypes of the organism were found among isolates from invasive disease cases and no dominant strains were observed. To determine whether any FBPs is associated with invasive disease propensity of S. pyogenes, we have screened streptococcal isolates from bacteraemic and necrotizing fasciitis patients and isolates from uncomplicated infections for genetic endowment of 4 FBPs. No difference was observed in the distribution of sfbII, fbp54 and sfbI between the blood isolates and isolates from uncomplicated infection. We conclude that the presence of sfbI does not appear to promote invasive diseases, despite its association with persistence. We also show a higher proportion of group A streptococcus strains isolated from invasive disease cases possess prtFII when compared to strains isolated from non-invasive disease cases. We suggest that S. pyogenes may recruit different FBPs for different purposes.

Torquoselectivity induced by lone-pair conjugation in the electrocyclic reactions of 1-azapolyenes

Torquoselectivity in the electrocyclic interconversions of 1-azapolyenes and their heterocyclic isomers was investigated theoretically. The ring openings of 1,2-dihydroazete, 1,2-dihydropyridine, and 1,2-dihydroazocine were examined using HF, MP2, and B3LYP calculations. A large preference for inward rotation of the nitrogen lone pair and outward rotation of the N-H group was found for the four- and six-electron systems. No strong preference was observed for the eight-electron system.

Predictors of positive axillary lymph nodes after sentinel lymph node biopsy in breast cancer

OBJECTIVE

The purpose of this study was to determine the factors that predict the presence of metastasis in nonsentinel lymph nodes (SLN) when the SLN is positive.

METHODS

A prospective database was analyzed and included patients who underwent SLN biopsy for invasive breast cancer from July 1997 to August 2000 (n = 442). One hundred (22.6%) patients had one or more positive SLNs, and were analyzed to determine factors that predicted additional positive axillary nodes.

RESULTS

Of the 100 patients with a positive SLN, 40 patients (40%) had additional metastasis in non-SLNs. The only significant variables that predicted non-SLN metastasis were tumor lymphovascular invasion (P = 0.004), extranodal extension (P < 0.001), and increasing size of the metastasis within the SLN (P = 0.011). In analyzing just those patients who had lymphovascular invasion, extranodal extension, and a SLN metastasis > 2mm, 92% were found to have additional positive nodes.

CONCLUSIONS

In patients with invasive breast cancer and a positive sentinel lymph node, lymphovascular invasion, extranodal extension, and increasing size of the metastasis all significantly increase the frequency of additional positive nodes.

Selective analysis of the sentinel node in breast cancer

BACKGROUND

This study was designed to determine the minimum number of sentinel nodes necessary to accurately stage patients with breast cancer.

METHODS

Between August 1997 and February 2001, 509 consecutive patients were enrolled in a prospective sentinel node database. Nodes were characterized as either blue or hot (>2 times background), or both, and ranked based on the order harvested. Predictive value of the sentinel node based on these characteristics was evaluated to determine the minimum number necessary to stage the basin.

RESULTS

In all, 990 sentinel nodes were harvested from 465 basins. Pathologic stage in 126 of 128 positive basins was predicted by the first or second node harvested. The remaining 2 patients were positive by immunohistochemistry only. The hottest node predicted the status in 114 of 128 basins.

CONCLUSIONS

Although all nodes should be examined, these data suggest that limiting frozen section analysis to the first two sentinel nodes identified will not compromise the accuracy of staging and may provide a vehicle for resource savings.

Determination of an arylether antiarrhythmic and its N-dealkyl metabolite in rat plasma and hepatic microsomal incubates using liquid chromatography-tandem mass spectrometry

A method was developed and validated for the quantification of (+/-)-trans-[2-morpholino-1-(1-naphthalene-ethyloxy]cyclohexane monohydrochloride (RSD1070) and its N-dealkyl metabolite in rat plasma and hepatic microsomal incubates. Chromatographic separations were achieved using reversed-phase high-performance liquid chromatography coupled with positive ion electrospray ionization and detection by tandem mass spectrometry. The assay was linear from 2.5 to 100 ng/ml and this range was used for validation. Inter- and intra-assay variability (n=6), extraction recovery, and stability in plasma were assessed. The estimated limit of quantitation was in the range 2.5-3 ng/ml for both analytes in rat plasma. The analytical method was used in a pharmacokinetic study of RSD1070 in rats after a single i.v. bolus of 12 mg/kg.

The virulence factors ofBordetella pertussis: a matter of control

Bordetella pertussis is the causative agent of whooping cough, a contagious childhood respiratory disease. Increasing public concern over the safety of whole-cell vaccines led to decreased immunisation rates and a subsequent increase in the incidence of the disease. Research into the development of safer, more efficacious, less reactogenic vaccine preparations was concentrated on the production and purification of detoxified B. pertussis virulence factors. These virulence factors include adhesins such as filamentous haemagglutinin, fimbriae and pertactin, which allow B. pertussis to bind to ciliated epithelial cells in the upper respiratory tract. Once attachment is initiated, toxins produced by the bacterium enable colonisation to proceed by interfering with host clearance mechanisms. B. pertussis co-ordinately regulates the expression of virulence factors via the Bordetella virulence gene (bvg) locus, which encodes a response regulator responsible for signal-mediated activation and repression. This strict regulation mechanism allows the bacterium to express different gene subsets in different environmental niches within the host, according to the stage of disease progression.

The common ovine Shiga toxin 2-containing Escherichia coli serotypes and human isolates of the same serotypes possess a Stx2d toxin type

Shiga toxin 2 (Stx2) has been reported as the main Shiga toxin associated with human disease. In addition, the Stx2 toxin type can have a profound impact on the degree of tissue damage in animal models. We have characterized the stx(2) subtype of 168 Shiga toxin-producing Escherichia coli (STEC) isolates of which 146 were derived from ovine sources (principally feces and meat) and 22 were isolated from humans. The ovine STEC isolates were of serotypes that have been shown to occur commonly in the gastrointestinal tract of healthy sheep. The major stx(2) subtype in the ovine isolates was shown to be stx(2d-Ount) (119 of 146 [81.5%]) and was predominantly associated with serotypes O75:H(-)/H8/H40, O91:H(-), O123:H(-), O128:H2, and OR:H2. However, 17 of 18 (94.4%) ovine isolates of serotype O5:H(-) possessed a stx(2d-O111/OX3a) subtype. Furthermore, STEC isolates of serotypes commonly found in sheep and recovered from both clinical and nonclinical human infections also contained a stx(2d) (stx(2d-Ount/O111/OX3a)) subtype. These studies suggest that a specific stx(2) subtype(s) associates with serotype and may have important epidemiological implications for tracing sources of E. coli during outbreaks of STEC-associated diseases in humans.

Oral immunization of swine with attenuated Salmonella typhimurium aroA SL3261 expressing a recombinant antigen of Mycoplasma hyopneumoniae (NrdF) primes the immune system for a NrdF specific secretory IgA response in the lungs

Salmonella typhimurium SL3261 (aroA mutant) expressing a recombinant Mycoplasma hyopneumoniae antigen was used to orally immunize swine against porcine enzootic pneumonia. This construct, designated S. typhimurium aro A SL3261 (pKF1), expressed a recombinant protein containing the carboxy-terminal 11 kDa of a 42 kDa M. hyopneumoniae NrdF ribonucleotide reductase R2 subunit protein. Here we demonstrate that this antigen is present in all seven geographically diverse strains of M. hyopneumoniae tested, and is recognized by the swine immune system after experimental infection with the virulent M. hyopneumoniae Beaufort strain. The immune response of swine orally immunized twice with S. typhimurium SL3261 (pKF1) on day 0 and day 14 was evaluated. Oral immunization with S. typhimurium SL3261 (pKF1) primed the immune system to elicit a significant (P<0.05) secretory IgA response against the 15 kDa NrdF antigen in the respiratory tract of swine, post-challenge, compared to control groups. Blood lymphocytes from swine immunized with S. typhimurium SL3261 (pKF1) proliferated significantly (P<0.05) following stimulation with M. hyopneumoniae whole-cell extracts compared to control groups 14 days post-vaccination. Following challenge with virulent M. hyopneumoniae, swine immunized with S. typhimurium SL3261 (pKF1) showed higher average daily weight gains and reduced lung pathology compared to control groups.

In vitro investigation of the hepatic extraction of RSD1070, a novel antiarrhythmic compound

PURPOSE

The hepatic extraction of a novel antiarrhythmic, RSD1070, was investigated to test the hypothesis that the poor bioavailability observed in rats is due to high hepatic metabolism.

METHODS

The pharmacokinetics of RSD1070 was examined in rats (n=8) and its metabolism was investigated using pooled rat hepatic microsomes. The free fraction in plasma and microsomal matrices was determined by equilibrium dialysis. Hepatic extraction was predicted by scaling-up of the microsomal kinetic data using the well-stirred liver model.

RESULTS

RSD1070 demonstrated tri-exponential decay following single iv bolus administration of a dose of 12 mg/kg. RSD1070 exhibited a rapid elimination, t1/2 of 25 +/- 8 min and a CL(tot) of 71 +/- 9 mL/min/kg. Renal clearance based on 24 h urinary recovery was determined to be insignificant (<< 1% of CL(tot)). A Michaelis-Menten model described the elimination of RSD1070 with a K(m) of 0.45 microg/mL and Vmax of 2.81 microg/min/mg microsomal protein. Taking the V(max)/K(m) ratio (CL(int)) as the basis for scaling, the data from the microsomal kinetic studies (75 mL/min/kg) closely approximated the apparent CL(tot). In the scale-up of the in vitro CL(int), plasma free fraction (1.5%) and microsomal free fraction (15%) were determined and incorporated into the well-stirred liver model.

CONCLUSION

RSD1070 is a high hepatic extraction compound (E = 0.94) with a predicted CL(h) value that accounted for the CL(tot) observed in rats.

Intratumoral injection of dendritic cells derived in vitro in patients with metastatic cancer

BACKGROUND

Dendritic cells (DCs) are potent initiators of immune responses, and the infiltration of DCs into tumors may confer an improved prognosis. Whether the injection of DCs directly into tumors can mediate biologic activity was examined.

METHODS

Patients with metastatic dermal or subcutaneous tumors received granulocyte-macrophage-colony stimulating factor to increase the numbers of peripheral blood monocyte precursors. DCs were then generated from monocytes obtained by phlebotomy with granulocyte-macrophage-colony stimulating factor and interleukin-4 in autologous plasma. Tumors were injected at multiple sites with 30 million autologous DCs per tumor.

RESULTS

Seven patients with melanoma and three patients with breast carcinoma were treated. Injections were well tolerated. Regression of the injected tumors, beginning as early as 4 days after injection, was observed in four patients with melanoma and in two patients with breast carcinoma. Biopsies of regressing lesions showed lymphocyte infiltration associated with DCs and necrosis. Neutrophils and macrophages were not evident. Lymphocytes expanded from the regressing tumors proliferated in response to heat shock proteins, HSP70 and gp96, derived from autologous tumor. The DCs injected produced interferon-alpha and expressed Fas ligand mRNA but did not exhibit cytolytic activity in vitro. Expression of the costimulatory molecule, B7-2 (CD86), decreased on DCs after intratumoral injection.

CONCLUSIONS

This pilot study demonstrates that DCs derived in vitro can exist viably after intratumoral injection and can mediate biologic activity in situ. Tumor-derived heat shock proteins may be involved in the antitumor activity observed.

Co-expression of the Bordetella pertussis leader peptidase I results in enhanced processing and expression of the pertussis toxin S1 subunit in Escherichia coli

Bordetella pertussis is the causative agent of whooping cough. Traditional vaccines against this disease are inherently reactogenic, thus research is currently focussed on the production of less reactive, acellular vaccines. Expression of candidate antigens for these vaccines in Escherichia coli would be preferable, however, several B. pertussis antigens undergo incorrect post-translational processing in E. coli. The leader peptidase gene (lep) of B. pertussis encodes a protein of 294 amino acid residues that shares homology with other prokaryote leader peptidase I sequences. Hydrophilicity analysis based on the predicted amino acid sequence has demonstrated a similar membrane topology to that of E. coli and Salmonella typhimurium leader peptidase I. Co-expression of the B. pertussis lep gene in E. coli strain TOPP2 expressing the pertussis toxin S1 subunit was found to markedly increase the expression and post-translational processing of the S1 protein.

Epigenetic PTEN silencing in malignant melanomas without PTEN mutation

A tumor suppressor gene at 10q 23.3, designated PTEN, encoding a dual specificity phosphatase with lipid and protein phosphatase activity, has been shown to play an important role in the pathogenesis of a variety of human cancers. Germline mutations in PTEN cause Cowden syndrome (CS), which is characterized by multiple hamartomas and a high risk of breast and thyroid cancers. Frequent loss of heterozygosity at 10q is found in both early and advanced-stage sporadic melanomas; however, mutations or deletions in PTEN are detected mainly in melanoma cell lines. In this study, we examined PTEN expression in 34 unselected sporadic melanomas (4 primary melanomas, 30 metastases) using immunohistochemistry and correlated this with the results of structural studies of this gene. Immunostaining of 34 melanoma samples revealed no PTEN expression in 5 (15%) and low PTEN expression in 17 (50%), whereas the rest of the tumors (35%) had high levels of expression. Hemizygous deletion was found in 32% of the tumors but neither intragenic PTEN mutation nor biallelic deletion was found in any of the samples. Of the 5 melanomas showing no PTEN expression, 4 had no mutation or deletion of PTEN. Of the 13 tumors having weak PTEN immunoreactivity and informative loss of heterozygosity results, 6 had evidence of hemizygous allelic loss of PTEN while the remaining 7 had intact PTEN. These results strongly support PTEN as a major tumor suppressor on 10q involved in melanoma tumorigenesis and suggest an epigenetic mechanism of biallelic functional inactivation not previously observed in other cancers where PTEN might be involved.

Role of phosphoglucomutase of Bordetella bronchiseptica in lipopolysaccharide biosynthesis and virulence

The phosphoglucomutase (PGM)-encoding gene of Bordetella bronchiseptica is required for lipopolysaccharide (LPS) biosynthesis. An insertion mutant of the wild-type B. bronchiseptica strain BB7865 which disrupted LPS biosynthesis was created and characterized (BB7865pgm). Genetic analysis of the mutated gene showed it shares high identity with PGM genes of various bacterial species and forms part of an operon which also encompasses the gene encoding phosphoglucose isomerase. Functional assays for PGM revealed that enzyme activity is expressed in both bvg-positive and bvg-negative strains of B. bronchiseptica and is substantially reduced in BB7865pgm. Complementation of the mutated PGM gene with that from BB7865 restored the wild-type condition for all phenotypes tested. The ability of the mutant BB7865pgm to survive within J774. A1 cells was significantly reduced at 2 h (40% reduction) and 24 h (56% reduction) postinfection. BB7865pgm was also significantly attenuated in its ability to survive in vivo following intranasal infection of mice, being effectively cleared from the lungs within 4 days, whereas the wild-type strain persisted at least 35 days. The activities of superoxide dismutase, urease, and acid phosphatase were unaffected in the PGM-deficient strain. In contrast, the inability to produce wild-type LPS resulted in a reduced bacterial resistance to oxidative stress and a higher susceptibility to the antimicrobial peptide cecropin P.

Ischaemia selectivity confers efficacy for suppression of ischaemia-induced arrhythmias in rats

Eight novel and three reference antiarrhythmics were investigated in anaesthetised rats for antiarrhythmic actions, as well as for effects on the electrocardiogram (ECG) under normal and "simulated ischaemic" conditions. In rats subjected to coronary artery occlusion lidocaine, (+/-)-trans-[2-(4-morpholinyl)-cyclohexyl]naphthyl-1-acetate, RSD1000 and (+/-)-trans-[2-(4-morpholinyl)-cyclohexyl]-2-(1-naphthyl)propionate, RSD1030, (Group A) produced dose-related and complete antiarrhythmic protection. Group B compounds, such as (+/-)-trans-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]-3, 4-dichlorocinnamamide, RSD995, produced complete antiarrhythmic protection but had aberrant dose-response curves. Group C compounds, such as quinidine and flecainide, failed to give full antiarrhythmic protection and had shallow dose-response curves. The potency of Group A compounds, but not Group B or C compounds, for ECG actions indicative of Na(+) channel blockade (prolongation of PR and QRS intervals) were significantly increased under "simulated ischaemic" conditions ([K(+)] 10 mM and pH 6.4) in isolated rat hearts. Thus, compounds with ischaemia-selective actions provided superior protection against ischaemia-induced arrhythmias in rats.

Expression and purification of recombinant human indoleamine 2, 3-dioxygenase

Indoleamine 2,3-dioxygenase, the first and rate-limiting enzyme in human tryptophan metabolism, has been implicated in the pathogenesis of many diseases. The human enzyme was expressed in Escherichia coli EC538 (pREP4) as a fusion protein to a hexahistidyl tag and purified to homogeneity in terms of electrophoretic and mass spectroscopic analysis, by a combination of phosphocellulose and nickel-agarose affinity chromatography. The yield of the fusion protein was 1.4 mg per liter of bacterial culture with an overall recovery of 56% from the crude extract. When the culture medium was supplemented with 7 microM hemin, the purified protein contained 0.8 mol of heme per mole of enzyme and exhibited an absorption spectrum consistent with the ferric form of hemoprotein. The pI value of the recombinant enzyme was 7.09 compared with 6.9 for the native enzyme. This was as expected from the addition of the hexahistidyl tag. Similar to the native enzyme, the recombinant enzyme required methylene blue and ascorbic acid for enzyme activity and oxidized not only l-tryptophan but also d-tryptophan and 5-hydroxy-l-tryptophan. The molecular activities for these substrates and their K(m) values were similar to those of the native enzyme, indicating that the addition of the hexahistidyl tag did not significantly affect catalytic activity. The recombinant protein can therefore be used to investigate properties of the native enzyme. This will aid the development of specific inhibitors of indoleamine 2,3-dioxygenase, which may be effective in halting disease progression.

Regulation of indoleamine 2,3-dioxygenase, the first enzyme in UV filter biosynthesis in the human lens. Relevance for senile nuclear cataract

3-Hydroxykynurenine (3OHKyn), the precursor of UV filters in human lens, is highly autooxidizable, generates H2O2, and binds to lens proteins, yielding a tanned/yellow product resembling senile nuclear cataractous materials. Thus, if 3OHkyn can be shown to be the causative agent in cataract, it may be possible to prevent the disease by lowering the level of 3OHKyn. To this end, indoleamine 2,3-dioxygenase, the first enzyme in UV filter synthesis, was studied using lens epithelial cell lines. The results indicated that the IDO expression is mediated by IFN-gamma. Immuno-suppressants which inhibit production of IFN-gamma may act as anti-cataract agents. Another way to lower the level of 3OHKyn is to use specific inhibitors for IDO. A recombinant human IDO was expressed to develop the inhibitors.

Pharmacology--a unique discipline for unique questions?

This article discusses the nature and responsibilities of the biomedical subject known as pharmacology. It will attempt to show how pharmacology is a very special subject that is uniquely positioned to ask fundamental questions about drugs, such as how they produce their actions, and how they may be used more effectively in man. Furthermore, pharmacology is a most important subject to the pharmaceutical industry as it is pharmacology, combined with medicinal chemistry and toxicology, that is responsible for the introduction of the vast majority of new drugs. Thus, pharmacologists are to be found in universities, research institutes and industry. In universities, pharmacologists are concerned more with discovering new drug-like entities in the body and natural world and in understanding how current drugs work. In industry, pharmacologists seek new drugs. Over the last decade there have been many discoveries in molecular biology, the new biology. The enthusiasm and revolutionary spirit which greets such discoveries leads to an assumption by some that pharmacology in its present form has been rendered redundant. This article refutes such a conclusion and shows how pharmacology has unique attributes and approaches that are as important now as they always were. Indeed, it argues for improvements in the understanding of pharmacology and how it remains a unique and special subject that should be nurtured.

Cardiac transplantation does not effect ischaemia-induced arrhythmias in rats

OBJECTIVE

In many species arrhythmias induced by myocardial ischaemia appear to be in part dependent upon cardiac sympathetic nerves. However, previous experiments in rats did not suggest that myocardial or other catecholamines are involved in ischaemic arrhythmogenesis in this species. The aim of this study was to investigate this further using transplanted hearts.

METHODS

We transplanted 'donated' hearts onto the abdominal aorta of recipient rats and, at varying periods after transplantation, subjected donated and recipient hearts to occlusion of the left anterior descending (LAD) coronary artery. Donated and recipient hearts were tested at various times after transplantation for responsiveness to drugs acting upon aspects of the autonomic nervous system. The intention of this latter study was to assess the status of innervation and receptors simultaneously in both donated and recipient hearts.

RESULTS

Donated (transplanted) hearts showed responses consistent with denervation and receptor supersensitivity. Changes varied with the duration of the transplant. Over the same period recipient hearts did not change in responsiveness to drugs. When subjected to coronary artery occlusion, transplanted hearts responded to occlusion with the same frequency and severity of arrhythmias as recipient and other control hearts, regardless of the duration of transplant, or sensitivity to drugs.

CONCLUSIONS

The results of these experiments suggest that cardiac innervation is not an important factor in the genesis of ischaemia-induced arrhythmias in rats.

Expression of urease does not affect the ability of Bordetella bronchiseptica to colonise and persist in the murine respiratory tract

To investigate the role played by urease during the Bordetella bronchiseptica infection process, the ability to colonise and persist in the mouse respiratory tract of a urease-negative B. bronchiseptica BB7865 and a BB7865 derivative constitutively expressing urease was compared with that of the wild-type strain. The results obtained showed that neither constitutive expression nor abolishment of urease activity had any significant effect on the course of B. bronchiseptica infection. Therefore, under our experimental conditions, urease is not essential for B. bronchiseptica to colonise and persist within the murine host.