Splanchnic vein thrombosis in myeloproliferative neoplasms: Pathophysiology and molecular mechanisms of disease

Myeloproliferative neoplasms (MPNs) are the most common underlying prothrombotic disorder found in patients with splanchnic vein thrombosis (SVT). Clinical risk factors for MPN-associated SVTs include younger age, female sex, concomitant hypercoagulable disorders, and the JAK2 V617F mutation. These risk factors are distinct from those associated with arterial or deep venous thrombosis (DVT) in MPN patients, suggesting disparate disease mechanisms. The pathophysiology of SVT is thought to derive from local interactions between activated blood cells and the unique splanchnic endothelial environment. Other mutations commonly found in MPNs, including CALR and MPL, are rare in MPN-associated SVT. The purpose of this article is to review the clinical and molecular risk factors for MPN-associated SVT, with particular focus on the possible mechanisms of SVT formation in MPN patients

Effect of acute and chronic pressure-threshold inspiratory muscle training on upper and lower airway function

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.There is evidence to suggest that inspiratory muscle training (IMT) may influence the functional properties of the muscles of the upper (UA) and lower (LA) airway. However, the nature and functional relevance of this influence is currently unclear. This thesis examined the effect of acute and chronic IMT in the context of UA and LA function. The ability of IMT to activate the UA dilator muscles, genioglossus (GG) and geniohyoid (GH), was examined using magnetic resonance imaging (MRI), as was the effect of chronic training on these muscles. In addition, the effect of acute and chronic IMT upon LA resistance (Rrs) and function was investigated in people with asthma using the Forced Oscillation Technique and conventional spirometry. For the UA, an acute bout of IMT at 60% maximal inspiratory mouth pressure (MIP) resulted in significant GG and GH activation (P < 0.001) as demonstrated by increases in the transverse relaxation time of muscle water (T2). Despite this, MRI was unable to detect any effect of chronic IMT upon UA function. For the LA, the usual increase in Rrs, following deep inhalation (DI) in people with asthma was attenuated with both single and multiple breaths against a pressure-threshold load equal to 50% MIP. However, six weeks IMT had no effect on baseline airway function or response to DI. In conclusion, an acute effect of pressure-threshold IMT upon UA and LA function was demonstrated. A strong rationale for a beneficial influence of chronic pressure-threshold IMT was therefore demonstrated. However, the data were insufficient to either reject, or accept the hypothesis that IMT exerts more than a transient influence upon UA and LA function, but insights are presented that support the need for further investigations.This work is funded by Harry Brar and HaB International Ltd

Acute effects of inspiratory pressure threshold loading upon airway resistance in people with asthma

This is the post-print version of the final paper published in Respiratory Physiology & Neurobiology. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2009 Elsevier B.V.Large inspiratory pressures may impart stretch to airway smooth muscle and modify the response to deep inspiration (DI) in asthmatics. Respiratory system resistance (Rrs) was assessed in response to 5 inspiratory manoeuvres using the forced oscillation technique: (a) single unloaded DI; (b) single DI at 25 cmH2O; (c) single DI at 50% maximum inspiratory mouth pressure [MIP]; (d) 30 DIs at 50% MIP; and (e) 30 DIs at 50% MIP with maintenance of normocapnia. Rrs increased after the unloaded DI and the DI at 25 cmH2O but not after a DI at 50% MIP (3.6 ± 1.6 hPa L s−1 vs. 3.6 ± 1.5 hPa L s−1; p = 0.95), 30 DIs at 50% MIP (3.9 ± 1.5 hPa L s−1 vs. 4.2 ± 2.0 hPa L s−1; p = 0.16) or 30 DIs at 50% MIP under normocapnic conditions (3.9 ± 1.5 hPa L s−1 vs. 3.9 ± 1.5 hPa L s−1; p = 0.55). Increases in Rrs in response to DI were attenuated after single and multiple loaded breaths at 50% MIP

Conservation gap analysis of dipterocarp hotspots in Sarawak using GIS, remote sensing and herbarium data

Dipterocarpaceae is the dominant tree family in the tropical rain forests of Southeast Asia. Borneo is the centre of diversity for the dipterocarps. Identification of hotspots is important for forest and biodiversity conservation efforts. Species Occurrence Models (SOMs) were generated for all 247 species of dipterocarps recorded in Sarawak using herbarium occurrence data and based on the best model selected. The species occurrence density map for each genus and category (endemic and non endemic) was generated by overlaying the SOMs of all species in each genus or category. The species occurrence density maps were analyzed with land cover map from Landsat 7-EMT+ images and protected forest areas for identifying hotspots for conservation in Sarawak. Overlaying the SOM maps revealed that areas in central Sarawak and the southwest region (northwest Borneo around Kuching) are the main hotspots of dipterocarp diversity in Sarawak while the coastal lowland areas in the lower Rejang and Baram River which are mainly peat swamp forest are poorer in species occurrence density. In terms of endemism, as with dipterocarp diversity, the mixed diptercarp forest of central Sarawak is also the most important hotspot. Gap analysis revealed that most protected forest areas are in southwest Sarawak (Bako, Kubah, Tanjung Datu and Gunung Gading National Parks) and in the northern part of Sarawak (Niah, Lambir Hills and Mt Mulu National Parks). This leaves the hotspot in the central part of Sarawak least protected. Protected areas only cover between 2 and 4% of the total areas for the different hotspots (75% species density) while majority of the hotspots that are still forested are outside the protected areas

Deforestation, forest degradation and readiness of local people of Lubuk Antu, Sarawak for REDD+

Reducing emissions from deforestation and forest degradation-plus (REDD+) is considered as an important mitigation strategy against global warming. However, the implementation of REDD+ can adversely affect local people who have been practicing shifting cultivation for generations. We analyzed Landsat-5 Thematic Mapper images of 1990 and 2009 to quantifying deforestation and forest degradation at Lubuk Antu District, a typical rural area of Sarawak, Malaysia. The results showed significant loss of intact forest at 0.9% per year, which was substantially higher than the rate of Sarawak. There were increases of oil palm and rubber areas but degraded forest, the second largest land cover type, had increased considerably. The local people were mostly shifting cultivators, who indicated readiness of accepting the REDD+ mechanism if they were given compensation. We estimated the monthly willingness to accept (WTA) at RM462, which can be considered as the opportunity cost of foregoing their existing shifting cultivation. The monthly WTA was well correlated with their monthly household expenses. Instead of cash payment, rubber cultivation scheme was the most preferred form of compensation

Effect of acute and chronic pressure-threshold inspiratory muscle training on upper and lower airway function

There is evidence to suggest that inspiratory muscle training (IMT) may influence the functional properties of the muscles of the upper (UA) and lower (LA) airway. However, the nature and functional relevance of this influence is currently unclear. This thesis examined the effect of acute and chronic IMT in the context of UA and LA function. The ability of IMT to activate the UA dilator muscles, genioglossus (GG) and geniohyoid (GH), was examined using magnetic resonance imaging (MRI), as was the effect of chronic training on these muscles. In addition, the effect of acute and chronic IMT upon LA resistance (Rrs) and function was investigated in people with asthma using the Forced Oscillation Technique and conventional spirometry. For the UA, an acute bout of IMT at 60% maximal inspiratory mouth pressure (MIP) resulted in significant GG and GH activation (P < 0.001) as demonstrated by increases in the transverse relaxation time of muscle water (T2). Despite this, MRI was unable to detect any effect of chronic IMT upon UA function. For the LA, the usual increase in Rrs, following deep inhalation (DI) in people with asthma was attenuated with both single and multiple breaths against a pressure-threshold load equal to 50% MIP. However, six weeks IMT had no effect on baseline airway function or response to DI. In conclusion, an acute effect of pressure-threshold IMT upon UA and LA function was demonstrated. A strong rationale for a beneficial influence of chronic pressure-threshold IMT was therefore demonstrated. However, the data were insufficient to either reject, or accept the hypothesis that IMT exerts more than a transient influence upon UA and LA function, but insights are presented that support the need for further investigations.EThOS - Electronic Theses Online ServiceHarry BrarHaB International LtdGBUnited Kingdo

Modeling the Natural Occurrence of Selected Dipterocarp Genera in Sarawak, Borneo

Dipterocarps or Dipterocarpaceae is a commercially important timber producing and dominant keystone tree family in the rain forests of Borneo. Borneo's landscape is changing at an unprecedented rate in recent years which affects this important biodiversity. This paper attempts to model the natural occurrence (distribution including those areas with natural forests before being converted to other land uses as opposed to current distribution) of dipterocarp species in Sarawak which is important for forest biodiversity conservation and management. Local modeling method of Inverse Distance Weighting was compared with commonly used statistical method (Binary Logistic Regression) to build the best natural distribution models for three genera (12 species) of dipterocarps. Database of species occurrence data and pseudoabsence data were constructed and divided into two halves for model building and validation. For logistic regression modeling, climatic, topographical and edaphic parameters were used. Proxy variables were used to represent the parameters which were highly (p>0.75) correlated to avoid over-fitting. The results show that Inverse Distance Weighting produced the best and consistent prediction with an average accuracy of over 80%. This study demonstrates that local interpolation method can be used for the modeling of natural distribution of dipterocarp species. The Inverse Distance Weighted was proven a better method and the possible reasons are discussed

Monitoring of deforestation and fragmentation in Sarawak, Malaysia between 1990 and 2009 using Landset and SPOT images

Sarawak is the largest state in Malaysia that covers 37.5% of the total land area. Multitemporal satellite images of Landsat and SPOT were used to examine deforestation and forest fragmentation in Sarawak between 1990 and 2009. Supervised classification with maximum likelihood classifier was used to classify the land cover types in Sarawak. The overall accuracies of all classifications were more than 80%. Our results showed that forests were reduced at 0.62% annually during the two decades. The peat swamp forest suffered a tremendous loss of almost 50% between 1990 and 2009 especially at coastal divisions due to intensified oil palm plantation development. Fragmentation analysis revealed the loss of about 65% of the core area of intact forest during the change period. The core area of peat swamp forest had almost completely disappeared during the two decades

The effect of preexercise expiratory muscle loading on exercise tolerance in healthy men

Purpose Acute non-fatiguing inspiratory muscle loading transiently increases diaphragm excitability and global inspiratory muscle strength, and may improve subsequent exercise performance. We investigated the effect of acute expiratory muscle loading on expiratory muscle function and exercise tolerance in healthy men. Methods Ten males cycled at 90% of peak power output to the limit of tolerance (TLIM) after: 1) 2 × 30 expiratory efforts against a pressure-threshold load of 40% maximal expiratory gastric pressure (PgaMAX) (EML-EX); and 2) 2 × 30 expiratory efforts against a pressure-threshold load of 10% PgaMAX (SHAM-EX). Changes in expiratory muscle function were assessed by measuring the mouth pressure (PEMAX) and PgaMAX responses to maximal expulsive efforts, and magnetically evoked (1-Hz) gastric twitch pressure (Pgatw). Results Expiratory loading at 40% of PgaMAX increased PEMAX (10 ± 5%, P = 0.001) and PgaMAX (9 ± 5%, P = 0.004). Conversely, there was no change in PEMAX (166 ± 40 vs. 165 ± 35 cmH2O, P = 1.000) or PgaMAX (196 ± 38 vs. 192 ± 39 cmH2O, P = 0.215) from before to after expiratory loading at 10% of PgaMAX. Exercise time was not different in EML-EX vs. SHAM-EX (7.91 ± 1.96 vs. 8.09 ± 1.77 min, 95% CI = −1.02 to 0.67, P = 0.651). Similarly, exercise-induced expiratory muscle fatigue was not different in EML-EX vs. SHAM-EX (−28 ± 12 vs. −26 ± 7% reduction in Pgatw amplitude, P = 0.280). Perceptual ratings of dyspnea and leg discomfort were not different during EML-EX vs. SHAM-EX. Conclusion Acute expiratory muscle loading enhances expiratory muscle function but does not improve subsequent severe-intensity exercise tolerance in healthy men

Mapping distribution of Dipterocarpus in East Kalimantan, Indonesia

Dipterocarps (Dipterocarpaceae) is a dominant tree family of tropical rainforest in Southeast Asia. Dipterocarps have been exploited for its timber and disappearing fast in East Kalimantan. In this study, we predicted the distribution of dipterocarpus, one of the main dipterocarps genera, by evaluating its habitat suitability using logistic regression analysis with specimen collection points and environmental factors from GIS data. Current distribution of dipterocarpus was generated by combining the habitat suitability classes with an updated forest cover map. Rainfall, soil type, followed by elevation was the main factors that influence the distribution of dipterocarpus in East Kalimantan. Dipterocarpus can be found in a quarter of the current forest cover, which is highly suitable as habitat of Dipterocarpus