Development of an atrial transseptal puncture procedure in horses to access the left heart: An ultrasound-guided jugular vein and transhepatic approach

BACKGROUND

Radiofrequency ablation has been successfully applied to treat right atrial arrhythmias in horses. Ablation of left-sided arrhythmias requires a retrograde transarterial approach which is complicated. In human medicine, the left atrium is accessed through transseptal puncture (TSP) of the fossa ovalis (FO) using a caudal approach via the femoral vein.

OBJECTIVES

To develop a zero fluoroscopy TSP technique for horses using a jugular vein (cranial) and transhepatic (caudal) approach.

STUDY DESIGN

In vivo experimental study.

METHODS

Transseptal puncture was performed in 18 horses admitted for euthanasia and donated for scientific research under general anaesthesia: using a jugular vein approach (10 horses), a transhepatic approach (2 horses) or both (6 horses). Radiofrequency energy was applied on a guidewire to perforate the FO and allow sheath advancement under intracardiac and transthoracic echocardiographic guidance. Puncture lesions were inspected post-mortem.

RESULTS

Transseptal puncture was successful in 17/18 horses, of which 15/16 jugular vein approaches and 5/8 transhepatic approaches. Failure was due to technical malfunction, inability to advance the guidewire toward the heart and inability to advance the sheath through the FO. Intracardiac echocardiography was essential to safely guide the puncture process. Atrial arrhythmias caused by the TSP occurred in 13/18 horses. Puncture lesions were found in the right atrium in the FO region, and left atrium ventral to pulmonary vein ostium III.

MAIN LIMITATIONS

Because in several horses two approaches were tested consecutively, it cannot be excluded that the second TSP was performed at the previous puncture site. Due to the developmental nature of the study the approaches were not randomised and did not allow comparison.

CONCLUSION

Transseptal puncture is feasible in horses using ultrasound guidance and allows for electrophysiological exploration of the left heart. Further studies are needed to evaluate post-operative follow-up.

Morphological evidence of a potential arrhythmogenic substrate in the caudal and cranial vena cava in horses

BACKGROUND

Three-dimensional electro-anatomical mapping, previously performed in horses with atrial arrhythmias, has demonstrated the medial region of the caudal vena cava (CaVC), 1-8 cm caudal to the fossa ovalis, as an anatomical predilection site for atrial tachycardia associated with areas of slow conduction and conduction block. Slow conduction has also been recorded in the cranial vena cava (CrVC).

OBJECTIVES

To investigate the morphological characteristics of the myocardial sleeves (MS) in the CaVC and CrVC, in order to identify a potential substrate of right sided atrial arrhythmias.

STUDY DESIGN

Cross sectional.

METHODS

Post-mortem dissection of 37 hearts from adult warmblood horses without known cardiovascular disease. Macroscopic examination of the myocardial distribution, evaluated the MS area, length, width, and shape in the CaVC and the CrVC. At least 2 samples from each vena cava MS were histologically examined using Masson's trichrome staining.

RESULTS

Myocardial sleeves into the medial CaVC and into the CrVC were observed in all horses and showed variations in distribution, shape, and size between horses. Their mean ± standard deviation length from the limbus into the CaVC reached 5.7 ± 1.0 cm (maximum 8.3 cm), and from the azygos vein into the CrVC 5.3 ± 1.6 cm (maximum 8.6 cm). Myocardium-free islands were observed in the CaVC and CrVC in 30% and 6% of horses, respectively. Histologically, MS showed a non-uniform myocardial fibre arrangement, with presence of fibroadipose tissue, features known to result in slow conduction and pro-arrhythmia.

MAIN LIMITATIONS

Study only included horses without history of atrial arrhythmia.

CONCLUSIONS

Myocardial sleeves are present in both CaVC and CrVC, showing anatomical variations between horses. Tissue characteristics known to favour re-entry were identified indicating that these venae cavae MS are a potential substrate for atrial tachyarrhythmias and a target for treatment by ablation.

Successful caudal vena cava and pulmonary vein isolation in healthy horses using 3D electro-anatomical mapping and a contact force-guided ablation system

BACKGROUND

Recently, treatment of equine atrial tachycardia by three-dimensional electro-anatomical mapping (3D EAM) and radiofrequency catheter ablation (RFCA) has been described. Myocardial sleeves in the caudal vena cava and pulmonary veins are a potential trigger for initiation and perpetuation of atrial tachycardia and atrial fibrillation in the horse. Isolation of these myocardial sleeves by RFCA may be an effective treatment for these arrhythmias.

OBJECTIVES

To describe the feasibility of 3D EAM and RFCA to isolate caudal vena cava and pulmonary veins in adult horses using 3D mapping and a contact force (CF)-guided ablation system.

STUDY DESIGN

In vivo experiments.

METHODS

3D EAM and RFCA was performed in five horses without cardiovascular disease under general anaesthesia, using the CF-guided system CARTO®3. Point-by-point RFCA aimed for isolation of caudal vena cava and pulmonary veins. Radiofrequency energy was delivered in power-controlled mode with a target power of 45 W, CF between 10 and 15 g and 30 mL/min irrigation rate, until an ablation-index of 450-500 was reached.

RESULTS

In the right atrium, myocardial sleeves of the caudal vena cava were isolated (n = 5). In the left atrium, isolation of ostium II (n = 3), ostium III (n = 1) and ostium I, II and III en bloc (n = 1) was performed. Successful isolation was confirmed by entrance and exit block.

MAIN LIMITATIONS

Horses were euthanised at the end of the procedure, so long term effects such as potential reconnection of isolated veins could not be studied.

CONCLUSIONS

This is the first description of 3D EAM and RFCA with CARTO®3 in horses, thereby showing the technical feasibility and successful caudal vena cava and pulmonary vein isolation. CF measurement allowed monitoring of catheter-tissue contact, resulting in efficient acute lesion creation as confirmed by entrance and exit block. This is a promising treatment for cardiac arrhythmias in horses.

Succinylation of a KEAP1 sensor lysine promotes NRF2 activation

Cross talk between metabolism and stress-responsive signaling is essential for maintaining cellular homeostasis. This cross talk is often achieved through covalent modification of proteins by endogenous, reactive metabolites that regulate key stress-responsive transcription factors like NRF2. Metabolites including methylglyoxal, glyceraldehyde 3-phosphate, fumarate, and itaconate covalently modify sensor cysteines of the NRF2 repressor KEAP1, resulting in stabilization of NRF2 and activation of its cytoprotective transcriptional program. Here, we employed a shRNA-based screen targeting the enzymes of central carbon metabolism to identify additional regulatory nodes bridging metabolism to NRF2 activation. Succinic anhydride, increased by genetic depletion of the TCA cycle enzyme succinyl-CoA synthetase or by direct administration, results in N-succinylation of lysine 131 of KEAP1 to activate NRF2 signaling. This study identifies KEAP1 as capable of sensing reactive metabolites not only by several cysteine residues but also by a conserved lysine residue, indicating its potential to sense an expanded repertoire of reactive metabolic messengers.

S-lactoyl modification of KEAP1 by a reactive glycolytic metabolite activates NRF2 signaling

KEAP1 (Kelch-like ECH-associated protein), a cytoplasmic repressor of the oxidative stress responsive transcription factor Nuclear factor erythroid 2-related factor 2 (NRF2), senses the presence of electrophilic agents by modification of its sensor cysteine residues. In addition to xenobiotics, several reactive metabolites have been shown to covalently modify key cysteines on KEAP1, although the full repertoire of these molecules and their respective modifications remain undefined. Here, we report the discovery of sAKZ692, a small molecule identified by high-throughput screening that stimulates NRF2 transcriptional activity in cells by inhibiting the glycolytic enzyme pyruvate kinase. sAKZ692 treatment promotes the buildup of glyceraldehyde 3-phosphate, a metabolite which leads to S-lactate modification of cysteine sensor residues of KEAP1, resulting in NRF2-dependent transcription. This work identifies a posttranslational modification of cysteine derived from a reactive central carbon metabolite and helps further define the complex relationship between metabolism and the oxidative stress-sensing machinery of the cell.

Succinylation of a KEAP1 sensor lysine promotes NRF2 activation

Crosstalk between metabolism and stress-responsive signaling is essential to maintaining cellular homeostasis. One way this crosstalk is achieved is through the covalent modification of proteins by endogenous, reactive metabolites that regulate the activity of key stress-responsive transcription factors such as NRF2. Several metabolites including methylglyoxal, glyceraldehyde 3-phosphate, fumarate, and itaconate covalently modify sensor cysteines of the NRF2 regulatory protein KEAP1, resulting in stabilization of NRF2 and activation of its cytoprotective transcriptional program. Here, we employed a shRNA-based screen targeting the enzymes of central carbon metabolism to identify additional regulatory nodes bridging metabolic pathways to NRF2 activation. We found that succinic anhydride, increased by genetic depletion of the TCA cycle enzyme succinyl-CoA synthetase or by direct administration, results in N-succinylation of lysine 131 of KEAP1 to activate NRF2 transcriptional signaling. This study identifies KEAP1 as capable of sensing reactive metabolites not only by several cysteine residues but also by a conserved lysine residue, indicating its potential to sense an expanded repertoire of reactive metabolic messengers.

Optimization of 3-aminotetrahydrothiophene 1,1-dioxides with improved potency and efficacy as non-electrophilic antioxidant response element (ARE) activators

Activating NRF2-driven transcription with non-electrophilic small molecules represents an attractive strategy to therapeutically target disease states associated with oxidative stress and inflammation. In this study, we describe a campaign to optimize the potency and efficacy of a previously identified bis-sulfone based non-electrophilic ARE activator 2. This work identifies the efficacious analog 17, a compound with a non-cytotoxic profile in IMR32 cells, as well as ARE activators 18 and 22, analogs with improved cellular potency. In silico drug-likeness prediction suggested the optimized bis-sulfones 17, 18, and 22 will likely be of pharmacological utility.

Acceptability of the Cognition Test Battery in Astronaut and Astronaut-Surrogate Populations

BACKGROUND

Sustained high levels of astronaut cognitive performance are a prerequisite for mission success. A neuropsychological battery of 10 brief cognitive tests (Cognition) covering a range of cognitive domains was specifically developed for high performing astronauts to objectively assess cognitive performance. Extended mission durations require repeated cognitive testing and thus high acceptability of the Cognition software to the astronaut population. The aim of this qualitative study was to evaluate acceptability of Cognition to astronauts and astronaut surrogate populations.

METHODS

Cognition was administered repeatedly to N=87 subjects (mean age ±SD 35.1 ±8.7 years, 52.8% male) on a laptop or iPad across five individual studies on the International Space Station or in space analog environments on Earth. Following completion of each study, participants were interviewed regarding their experience using Cognition in a semi-structured debrief. Participant comments were analyzed using a qualitative conventional content analysis approach.

RESULTS

The majority of participants' comments (86.1%) were coded as positive or neutral in valence, with most positive comments relating to software usability, engagement, and overall design. Among the 10 Cognition tests, subjects liked the Visual Object Learning Test most (28 likes, 32.2% of participants), while the Emotion Recognition Test was liked least (44 dislikes, 50.6% of participants). Some subjects (36.8%) were frustrated with the level of difficulty of some of the 10 Cognition tests, especially during early administrations, which was by design to avoid ceiling effects in repeated administrations of high-performers. Technical difficulties were rare (20.7% of participants), and most often observed in environments with restricted internet access. Most participants (82.3% of those who commented) liked the feedback provided by Cognition after each test, which includes a graph showing performance history.

CONCLUSION

Cognition was found to be acceptable to astronaut and astronaut-surrogate populations across a variety of settings and mission durations. Participant feedback provided was used to further improve Cognition and increase its acceptability during sustained space missions.

YAP-dependent proliferation by a small molecule targeting annexin A2

The transcriptional coactivator Yes-associated protein 1 (YAP) orchestrates a proproliferative transcriptional program that controls the fate of somatic stem cells and the regenerative responses of certain tissues. As such, agents that activate YAP may hold therapeutic potential in disease states exacerbated by insufficient proliferative repair. Here we report the discovery of a small molecule, termed PY-60, which robustly activates YAP transcriptional activity in vitro and promotes YAP-dependent expansion of epidermal keratinocytes in mouse following topical drug administration. Chemical proteomics revealed the relevant target of PY-60 to be annexin A2 (ANXA2), a protein that directly associates with YAP at the cell membrane in response to increased cell density. PY-60 treatment liberates ANXA2 from the membrane, ultimately promoting a phosphatase-bound, nonphosphorylated and transcriptionally active form of YAP. This work reveals ANXA2 as a previously undescribed, druggable component of the Hippo pathway and suggests a mechanistic rationale to promote regenerative repair in disease.

Discovery and SAR studies of 3-amino-4-(phenylsulfonyl)tetrahydrothiophene 1,1-dioxides as non-electrophilic antioxidant response element (ARE) activators

The transcription factor NRF2 controls resistance to oxidative insult and is thus a key therapeutic target for treating a number of disease states associated with oxidative stress and aging. We previously reported CBR-470-1, a bis-sulfone which activates NRF2 by increasing the levels of methylglyoxal, a metabolite that covalently modifies NRF2 repressor KEAP1. Here, we report the design, synthesis, and structure activity relationship of a series of bis-sulfones derived from this unexplored chemical template. We identify analogs with sub-micromolar potencies, 7f and 7g, as well as establish that efficacious NRF2 activation can be achieved by non-toxic analogs 7c, 7e, and 9, a key limitation with CBR-470-1. Further efforts to identify non-covalent NRF2 activators of this kind will likely provide new insight into revealing the role of central metabolism in cellular signaling.

Defining the Functional Targets of Cap'n'collar Transcription Factors NRF1, NRF2, and NRF3

The NRF transcription factors NRF1, NRF2, and NRF3, are a subset of Cap'n'collar transcriptional regulators which modulate the expression of genes harboring antioxidant-response element (ARE) sequences within their genomic loci. Despite the emerging physiological importance of NRF family members, the repertoire of their genetic targets remains incompletely defined. Here we use RNA-sequencing-based transcriptional profiling and quantitative proteomics to delineate the overlapping and differential genetic programs effected by the three NRF transcription factors. We then create consensus target gene sets regulated by NRF1, NRF2, and NRF3 and define the integrity of these gene sets for probing NRF activity in mammalian cell culture and human tissues. Together, our data provide a quantitative assessment of how NRF family members sculpt proteomes and transcriptomes, providing a framework to understand the critical physiological importance of NRF transcription factors and to establish pharmacologic approaches for therapeutically activating these transcriptional programs in disease.

Maternal lipids are associated with newborn adiposity, independent of GDM status, obesity and insulin resistance: a prospective observational cohort study

OBJECTIVE

To determine the association between maternal lipaemia and neonatal anthropometrics in Malaysian mother-offspring pairs.

DESIGN

Prospective observational cohort study.

SETTING

Single tertiary multidisciplinary antenatal clinic in Malaysia.

POPULATION

A total of 507 mothers: 145 with gestational diabetes mellitus (GDM); 94 who were obese with normal glucose tolerance (NGT) (pre-gravid body mass index, BMI ≥ 27.5 kg/m² ), and 268 who were not obese with NGT.

METHODS

Maternal demographic, anthropometric, and clinical data were collected during an interview/examination using a structured questionnaire. Blood was drawn for insulin, C-peptide, triglyceride (Tg), and non-esterified fatty acid (NEFA) during the 75-g 2-hour oral glucose tolerance test (OGTT) screening, and again at 36 weeks of gestation. At birth, neonatal anthropometrics were assessed and data such as gestational weight gain (GWG) were extracted from the records.

MAIN OUTCOME MEASURES

Macrosomia, large-for-gestational-age (LGA) status, cohort-specific birthweight (BW), neonatal fat mass (NFM), and sum of skinfold thickness (SSFT) > 90th centile.

RESULTS

Fasting Tg > 95th centile (3.6 mmol/L) at screening for OGTT was independently associated with LGA (adjusted odds ratio, aOR 10.82, 95% CI 1.26-93.37) after adjustment for maternal glucose, pre-gravid BMI, and insulin sensitivity. Fasting glucose was independently associated with a birthweight ratio (BWR) of >90th centile (aOR 2.06, 95% CI 1.17-3.64), but not with LGA status, in this well-treated GDM cohort with pre-delivery HbA1c of 5.27%. In all, 45% of mothers had a pre-gravid BMI of <23 kg/m² and 61% had a pre-gravid BMI of ≤ 25 kg/m² , yet a GWG of >10 kg was associated with a 4.25-fold risk (95% CI 1.71-10.53) of BWR > 90th centile.

CONCLUSION

Maternal lipaemia and GWG at a low threshold (>10 kg) adversely impact neonatal adiposity in Asian offspring, independent of glucose, insulin resistance and pre-gravid BMI. These may therefore be important modifiable metabolic targets in pregnancy.

TWEETABLE ABSTRACT

Maternal lipids are associated with adiposity in Asian babies independently of pre-gravid BMI, GDM status, and insulin resistance.

Small-Molecule Stimulators of NRF1 Transcriptional Activity

The transcription factor nuclear factor erythroid 2-related factor 1 (NRF1) maintains proteostasis and promotes cellular resilience by stimulating the transcription of proteasomal subunits and a host of protective enzymes. Although NRF1 activation would likely be beneficial in a number of disease states, information regarding its ligandability and upstream regulation are lacking. Herein we report a high-throughput chemical screen that identified selective stimulators of NRF1-driven transcription, including unannotated inhibitors of the ubiquitin proteasome system (UPS) as well as two non-UPS-targeted compounds that synergistically activate NRF1 in the context of submaximal UPS inhibition. This work introduces a suite of tool molecules to study the NRF1 transcriptional response and to uncover the druggable components governing NRF1 activity in cells.

Continuous glucose monitoring results in lower HbA1c in Malaysian women with insulin-treated gestational diabetes: a randomized controlled trial

AIMS

To determine if therapeutic, retrospective continuous glucose monitoring (CGM) improves HbA_1c with less hypoglycaemia in women with insulin-treated gestational diabetes mellitus (GDM).

METHODS

This prospective, randomized controlled, open-label trial evaluated 50 women with insulin-treated GDM randomized to either retrospective CGM (6-day sensor) at 28, 32 and 36 weeks' gestation (Group 1, CGM, n = 25) or usual antenatal care without CGM (Group 2, control, n = 25). All women performed seven-point capillary blood glucose (CBG) profiles at least 3 days per week and recorded hypoglycaemic events (symptomatic and asymptomatic CBG < 3.5 mmol/l; non-fasting < 4.0 mmol/l). HbA_1c was measured at 28, 33 and 37 weeks. In Group 1, both CGM and CBG data were used to manage diabetes, whereas mothers in Group 2 were managed based on CBG data alone.

RESULTS

Baseline characteristics (age, pre-pregnancy BMI, HbA_1c , total insulin dose) were similar between groups. There was a lower increase in HbA_1c from 28 to 37 weeks' gestation in the CGM group [∆HbA_1c : CGM + 1 mmol/mol (0.09%), control + 3mmol/mol (0.30%); P = 0.024]. Mean HbA_1c remained unchanged throughout the trial in the CGM group, but increased significantly in controls as pregnancy advanced. Mean HbA_1c in the CGM group was lower at 37 weeks compared with controls [33 ± 4 mmol/mol (5.2 ± 0.4%) vs. 38 ± 7 mmol/mol (5.6 ± 0.6%), P < 0.006]. Some 92% of the CGM group achieved an HbA_1c ≤ 39 mmol/mol (≤ 5.8%) at 37 weeks compared with 68% of the control group (P = 0.012). Neither group experienced severe hypoglycaemia.

CONCLUSION

CGM use may be beneficial in insulin-treated GDM because it improves HbA_1c compared with usual antenatal care without increasing severe hypoglycaemia. (Clinical Trials Registry No.: NCT02204657).

Hypopituitarism in a Dengue Shock Syndrome Survivor without known Pituitary Adenoma

Dengue infection is endemic in South East Asia and parts of the Americas. Dengue hemorrhagic fever is characterized by vascular permeability, coagulation-disorders and thrombocytopenia, which can culminate in hypotension i.e. dengue shock syndrome. Hypopituitarism arising as a complication of dengue is extremely rare. Hemorrhagic pituitary apoplexy of pre-existing pituitary adenomas has been rarely reported in dengue. We describe an uncommon case of hypopituitarism in a dengue shock syndrome survivor without known pituitary adenoma. A 49 years old nulliparous lady (from Kuala Lumpur, Malaysia) presented with typical symptoms of hypocortisolism. Postural hypotension was evident with normal secondary sexual characteristics. Further history revealed that she survived an episode of dengue shock syndrome 6 years ago where premature menopause developed immediately after discharge, and subsequently insidious onset of multiple hormonal deficiencies indicative of panhypopituitarism. There were no neuro-ophthalmological symptoms suggestive of pituitary apoplexy during hospitalization for severe dengue. Magnetic resonance imaging of the pituitary 6 years later revealed an empty sella. Autoimmune screen and anti-thyroid peroxidase antibodies were negative. We describe a rare possible causative association of severe dengue with panhypopituitarism without known pituitary adenoma, postulating pituitary infarction secondary to hypotension (mimicking Sheehan's syndrome), or a direct viral cytopathic effect. Subclinical pituitary apoplexy secondary to asymptomatic pituitary hemorrhage however cannot be excluded. Future research is required to determine the need for and timing of pituitary axis assessment among dengue shock syndrome survivors.

Hypothalamic pituitary dysfunction amongst nasopharyngeal cancer survivors

PURPOSE

Radiation fields for nasopharyngeal cancer (NPC) include the base of skull, which places the hypothalamus and pituitary at risk of damage. We aimed to establish the prevalence, pattern and severity of hypothalamic pituitary (HP) dysfunction amongst NPC survivors.

METHODS

We studied 50 patients (31 males) with mean age 57 ± 12.2 years who had treatment for NPC between 3 and 21 years (median 8 years) without pre-existing HP disorder from other causes. All patients had a baseline cortisol, fT4, TSH, LH, FSH, oestradiol/testosterone, prolactin and renal function. All patients underwent dynamic testing with insulin tolerance test to assess the somatotroph and corticotroph axes. Baseline blood measurements were used to assess thyrotroph, gonadotroph and lactotroph function.

RESULTS

Hypopituitarism was present in 82% of patients, 30% single axis, 28% two axes, 18% three axes and 6% four axes deficiencies. Somatotroph deficiency was most common (78%) while corticotroph, gonadotroph and thyrotroph deficiencies were noted in 40% (4 complete/16 partial), 22 and 4% of the patients respectively. Hyperprolactinaemia was present in 30% of patients. The development of HP dysfunction was significantly associated with the time elapsed from irradiation, OR 2.5 (1.2, 5.3), p = 0.02, for every 2 years post treatment. The use of concurrent chemo-irradiation (CCRT) compared to those who had radiotherapy alone was also significantly associated with HP dysfunction, OR 14.5 (2.4, 87.7), p < 0.01.

CONCLUSION

Despite low awareness and detection rates, HP dysfunction post-NPC irradiation is common. Use of CCRT may augment time related pituitary damage. As these endocrinopathies result in significant morbidity and mortality we recommend periodic assessment of pituitary function amongst NPC survivors.

Matrix metalloproteinase-9 gene polymorphism in hepatocellular carcinoma patients with hepatitis B and C viruses

Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide. In Egypt, the incidence of HCC has doubled over the last decade. Matrix metalloproteinase-9 (MMP-9) plays a key role in cancer invasion and metastasis by degrading the extracellular matrix and basement membrane barriers. A cytosine (C)/thymidine (T) single nucleotide polymorphism at position -1562 in the MMP-9 promoter is reported to influence the expression of the MMP-9 gene. The association between MMP-9 gene polymorphisms and HCC patients with hepatitis C and B viruses (HCV and HBV) was examined in 91 patients with HCC and viral hepatitis (55 HCV and 36 HBV). The results were compared with those of 42 HCC patients without viral hepatitis and 60 healthy individuals with no liver infection. Polymorphisms of the MMP-9 gene were investigated by polymerase chain reaction amplification followed by restriction fragment length polymorphism analysis. The serum MMP-9 level was quantitatively determined using a human MMP-9 enzyme-linked immunosorbent assay, which showed that homozygosity of the MMP-9 promoter (TT) was more frequent in patients with HCC and chronic HCV or HBV infection when compared with the control group (49.1, 52.8, and 35.7%, respectively). In addition, we observed significant elevation of serum MMP-9 levels in all HCC groups compared to controls. It was concluded that patients with the MMP-9 TT genotype are at risk of developing HCC and HBV or HCV. People with significantly elevated serum levels of MMP-9 are at risk of developing HCC.

A list of fish species that are potentially exposed to pesticides in edge-of-field water bodies in the European Union--a first step towards identifying vulnerable representatives for risk assessment

Surrogate species are used in standard toxicity tests for the environmental risk assessment of chemicals. Test results are then extrapolated to the situation in the field, which is often associated with a large degree of uncertainty. Since a vulnerable species in the field is not only characterised by its intrinsic sensitivity to a stressor but also by its potential for exposure and its population resilience, the identification of focal species based on these three components of vulnerability is needed for a more ecologically relevant risk assessment. This study listed European fish species that are susceptible to pesticide exposure in the field and thus achieved the first step towards identifying focal species for the risk assessment of pesticides for fish in Europe. A step-wise filtering approach was applied to list freshwater fish species that are native to Europe and widespread in the European Union, which inhabit streams, ditches or ponds in agricultural landscapes and therefore, are at an elevated risk of being exposed to pesticides. Out of the 579 fish species occurring in European freshwater, 27 species met the filtering criteria. The resulting list was verified based on monitoring studies that were conducted in agricultural landscapes over the past 20 years. Focal fish species that can be used for a more ecologically relevant environmental risk assessment of pesticides in Europe can be identified from the produced list of species by further assessing their ecological (life history and dispersal characteristics) and intrinsic sensitivities.

Interactive effects of nitrogen and water availabilities on gas exchange and whole-plant carbon allocation in poplar

Cuttings of balsam spire hybrid poplar (Populus trichocarpa var. Hastata Henry x Populus balsamifera var. Michauxii (Dode) Farwell) were grown in sand culture and irrigated every 2 (W) or 10 (w) days with a solution containing either 3.0 (N) or 0.5 (n) mol nitrogen m(-3) for 90 days. Trees in the WN (control) and wn treatments had stable leaf nitrogen concentrations averaging 19.4 and 8.4 mg g(-1), respectively, over the course of the experiment. Trees in the Wn and wN treatments had a similar leaf nitrogen concentration, which increased from 12.0 to 15.8 mg g(-1) during the experiment. By the final harvest, mean stomatal conductances of trees in the wN and wn treatments were less than those of trees in the Wn and WN treatments (1.8 versus 4.6 mm s(-1)). Compared to the WN treatment, biomass at the final harvest was reduced by 61, 72 and 75% in the Wn, wN and wn treatments, respectively. At the final harvest, WN trees had a mean total leaf area of 4750 +/- 380 cm(2) tree(-1) and carried 164 +/- 8 leaves tree(-1) with a specific leaf area of 181 +/- 16 cm(2) g(-1), whereas Wn trees had a smaller mean total leaf area (1310 +/- 30 cm(2) tree(-1)), because of the production of fewer leaves (41 +/- 6) with a smaller specific leaf area (154 +/- 2 cm(2) g(-1)). A greater proportion of biomass was allocated to roots in Wn trees than in WN trees, but component nitrogen concentrations adjusted such that there was no Wn treatment effect on nitrogen allocation. Compared with WN trees, rates of photosynthesis and respiration per unit weight of tissue of Wn trees decreased by 28 and 31%, respectively, but the rate of photosynthesis per unit leaf nitrogen remained unaltered. The wN and Wn trees had similar leaf nitrogen concentrations; however, compared with the Wn treatment, the wN treatment decreased mean total leaf area (750 +/- 50 cm(2) tree(-1)), number of leaves per tree (29 +/- 2) and specific leaf area (140 +/- 6 cm(2) g(-1)), but increased the allocation of biomass and nitrogen to roots. Net photosynthetic rate per unit leaf nitrogen was 45% lower in the wN treatment than in the other treatments. Rates of net photosynthesis and respiration per unit weight of tissue were 48 and 33% less, respectively, in wN trees than in Wn trees.

Primary human adult lung epithelial cells in vitro: response to interferon-gamma and cytomegalovirus

Primary human adult lung epithelial cells (ALEC) were established in culture using the most distal parts of the lung to avoid the airways. Immunocytochemical peroxidase staining and semiquantitative flow cytometry were used to characterize the cells in conjunction with a panel of monoclonal antibodies (mAb). The cells showed a constitutive expression of major histocompatibility complex (MHC) class I antigens, patchy expression of intercellular adhesion molecule-1 (ICAM-1) and a weak patchy expression of MHC class II antigens (detected using immunocytochemical staining). Incubation of the primary ALEC with interferon-gamma (IFN-gamma) (250 U/ml) stimulated an up-regulation of the expression of these three antigens to varying degrees; expression of MHC class I antigens and ICAM-1 molecules showed an up-regulation at 10 hr after the start of the treatment, reaching a peak at 48 hr, maintaining it for the next 24 hr and then, steadily and progressively, losing it towards the end of the experiment at 96 hr. Expression of HLA-DR showed an up-regulation at 17 hr after the start of the treatment, reaching a peak at 72 hr and maintaining it for the next 24 hr. Cytomegalovirus (CMV) infection of ALEC in culture caused an up-regulation of expression of class I antigens and ICAM-1, but not DR. However, when the infected cells were incubated with IFN-gamma, an up-regulation in the expression of DR took place. Therefore, within the micro-environment of the transplanted lung the presence of cytokines (IFN-gamma) produced by infiltrating activated mononuclear cells, may render the lung epithelial cells capable of acting as antigen-presenting cells, expressing high levels of class I antigens, ICAM-1 and class II antigens, activating CD8 and CD4 cells thus playing a major part in the process of rejection of the lung allograft; themselves becoming a primary target in the process.

Duffy phenotypes in Malaysian populations: correction of previous unusual findings

Duffy phenotypes were determined for 314 Malaysian Orang Asli. The most common gene, Fya, was present in 313; there were no Duffy negative individuals. A previous study found evidence of Plasmodium vivax infection in 5 of 7 Orang Asli reported to be of the Duffy negative genotype. In this study, 5 of the 7 previously tested Orang Asli were retested in triplicate, and each of the 5 was found to be Duffy positive, having the Fya gene and a phenotype of Fy (a + b-).

Effect of castration and testosterone propionate on mouse vibrissae

Vibrissae of normal mice were measured for six cycles starting at birth. Groups of immature male albino mice were castrated at 21 days of age when E, F, G and H (Danforth nomenclature, 1925) vibrissae were in their first cycle of growth. Levels of testosterone in their peripheral plasma were reduced to about one tenth of the normal. The final length achieved by their vibrissae in all subsequent cycles was shorter than that of normal mice. Another group of immature male mice were treated with implants of testosterone propionate to give plasma levels of approximately five to ten times normal. Their vibrissae showed a significant increase in final length in all growth cycles before and after sexual maturation. Vibrissae of adult male mice treated with excess testosterone showed a significant increase in final length at the end of the growth cycle immediately after commencement of treatment. On the other hand, vibrissae of castrated adult mice showed a significant decrease in final length in the second successive cycle after castration. The rate of growth of all vibrissae remained unchanged. Changes in their final length were brought about by changes in the period of growth. Castrated mice had a slightly longer resting period.

The long term effect of repeated pluckings on the function of the mouse vibrissal follicles

Single mouse vibrissae were plucked repeatedly at the same time of the cycle (10--15 days after eruption) for ten successive cycles from eight individual follicles. After three pluckings the first grey whisker appeared, after six pluckings all were grey. Two follicles stopped producing whiskers after seven pluckings and another two after the 8th. Henceforth only 50% of the follicles continued producing whiskers until the end of the experiment. All the follicles which ceased to produce whiskers had a keratogenous cyst occupying most of the follicle in direct contact with the dermal papilla. In all cases the isolated dermal papilla was condensed and rounded in shape. Both loss of pigment and cyst formation could be due to the mechanical damage in the follicle caused by repeated plucking.

The effect of a single plunking at different times in the hair cycle on the growth of individual mouse vibrissae

Mouse vibrissae have been plucked at precise times throughout the hair cycle and the time of appearance of the new hair noted for each individual follicle. It was found that plucking a vibrissa at any time during the cycle resulted in the induction of a new hair and in no case did the follicle continue the same cycle. All the vibrissae grew at the normal rate of 1.0 mm/day for most of the growing period and whenever plucked during this period a new hair appeared after 8--11 days. When the growth rate fell to 0.6--0.7mm/day at the end of the growing period plucking resulted in the appearance of a new hair after 7 days. When the growth rate fell to 0.1--0.3 mm/day a new hair appeared 5 days after plucking, thus the time of normal eruption was not altered. When whiskers were 10--15 mm long and about half way through the active growth phase their follicles were surgically transected at one of three different levels: (1) just above the dermal papilla which left all or most of the differentiating matrix cells, (2) mid-follicle and (3) at the level of the sebacaous gland. In each case the distal part of the hair was then plucked. In five out of ten cases when the cut was made just above the dermal papilla a new hair erupted after a variable time 10--15 days. In all other cases the existing hair cycle was completed after a delay of a few days. This emphasizes the importance of the differentiated matrix cells in the maintenance of the hair cycle.

The growth of rats and mice vibrissae under normal and some abnormal conditions

The growth of hair from the mystacial vibrissal follicles of C3H mice and Wistar rats has been measured for up to seven cycles. Normally growth in length and thickness was regular and little affected by age or sex. Plucking vibrissae at any stage during the growing period was followed by the appearance of a new vibrissa 8-11 days later. Plucking when growth had ceased had no effect on the time of appearance of the subsequent cycle. New whiskers emerging after plucking grew at the normal rate. Withholding food slowed the growth of vibrissae within 1 day. Normal growth was re-established 3 days after return to full diet.