Soil respiration, carbon and nitrogen leaching, and nitrogen availability in response to harvest intensity and competing vegetation control in Douglas-fir (Pseudotsuga menziesii) forests of the Pacific Northwest

Management practices following forest harvest can affect long-term soil productivity through alteration of soil carbon (C) and nitrogen (N) pools, but processes contributing to change are poorly understood. I assessed effects of three levels of logging-debris retention in combination with initial or annual applications of competing vegetation control (CVC) following forest harvesting on soil C flux, N leaching, foliar N of planted Douglas-fir, and changes in soil N and C pools for two years at two sites with contrasting soil properties. Soil C flux was lower when heavy amounts of logging debris were retained, due largely to lower bulk soil and microbial respiration as there was no difference in dissolved organic C (DOC) flux among logging-debris treatments. Increased soil C when heavy amounts of logging debris were retained at the site with lower initial soil C reflected the lower C flux, but soil C was increased at both sites when logging debris was removed, likely due to greater decomposition of belowground organic matter (OM). There was no difference in DOC leaching or soil C between CVC treatments at either site, despite lower OM inputs to mineral soil with annual CVC. Higher bulk soil respiration in the initial CVC treatment indicated that OM inputs from competing vegetation were rapidly consumed, and contributed little to mineral soil C. The most pronounced effects on N leaching and foliar N were associated with annual CVC, which increased Douglas-fir foliar N at both sites, and total N leaching below the rooting zone at the high-N site. However, estimated mass of leached N was small relative to the site soil N pool, and it is unlikely that the loss will negatively affect soil productivity. Logging-debris retention had little influence on Douglas-fir foliar status or N leaching, but soil N was higher at the end of the experiment when heavy amounts of logging debris were retained at the low-N site. There appears to be small potential for logging-debris removal and annual CVC to reduce soil productivity at these sites after harvesting, but logging-debris retention may improve soil productivity, particularly at sites with low initial pools of C and N

Bowel obstruction from wild bananas: a neglected health problem in Laos

We investigated the significance and risk factors of bowel obstruction caused by the consumption of wild bananas (BOWB) in Laos. Of six patients with BOWB in Luang Namtha, North Laos, five required enterotomy for phytobezoars. All had eaten wild banana (WB) seeds

Limited Effects of Precipitation Manipulation on Soil Respiration and Inorganic N Concentrations Across Soil Drainage Classes in Northern Minnesota Aspen Forests

It is critical to gain insight into the responses of forest soils to the changing climate. We simulated future climate conditions with growing season throughfall reduction (by 50%) and winter snow removal using a paired-plot design across a soil drainage class gradient at three upland, Populus-dominated forests in northern Minnesota, USA. In situ bulk soil respiration and concentrations of extractable soil N were measured during the summers of 2020–2021. Soil respiration and N concentrations were not affected by throughfall reduction and snow removal, which was largely attributed to the limited treatment effects on soil moisture content and soil temperature. Drainage class was only a significant factor during the spring thaw period in 2021. During this period, the poorly drained plots had lower respiration rates compared to the well-drained plots, which was associated with the drainage class effects on soil temperature. The results of the companion laboratory incubation with varying levels of soil moisture also indicated no effect of the treatment on soil respiration, but effects of drainage class and moisture content on respiration were observed. Our results indicate that the combined effects of reduced summer and winter precipitation on soil respiration and N dynamics may be limited across the range of conditions that occurred in our study

Fatal Chromobacterium violaceum septicaemia in northern Laos, a modified oxidase test and post-mortem forensic family G6PD analysis

<p>Abstract</p> <p>Background</p> <p><it>Chromobacterium violaceum </it>is a Gram negative facultative anaerobic bacillus, found in soil and stagnant water, that usually has a violet pigmented appearance on agar culture. It is rarely described as a human pathogen, mostly from tropical and subtropical areas.</p> <p>Case presentation</p> <p>A 53 year-old farmer died with <it>Chromobacterium violaceum </it>septicemia in Laos. A modified oxidase method was used to demonstrate that this violacious organism was oxidase positive. Forensic analysis of the glucose-6-phosphate dehydrogenase genotypes of his family suggest that the deceased patient did not have this possible predisposing condition.</p> <p>Conclusion</p> <p><it>C. violaceum </it>infection should be included in the differential diagnosis in patients presenting with community-acquired septicaemia in tropical and subtropical areas. The apparently neglected but simple modified oxidase test may be useful in the oxidase assessment of other violet-pigmented organisms or of those growing on violet coloured agar.</p

Chromoblastomycosis after a leech bite complicated by myiasis: a case report

Background Chromoblastomycosis is a chronic mycotic infection, most common in the tropics and subtropics, following traumatic fungal implantation. Case presentation A 72 year-old farmer was admitted to Luang Namtha Provincial Hospital, northern Laos, with a growth on the left lower leg which began 1 week after a forefoot leech bite 10 years previously. He presented with a cauliflower-like mass and plaque-like lesions on his lower leg/foot and cellulitis with a purulent tender swelling of his left heel. Twenty-two Chrysomya bezziana larvae were extracted from his heel. PCR of a biopsy of a left lower leg nodule demonstrated Fonsecaea pedrosoi, monophora, or F. nubica. He was successfully treated with long term terbinafin plus itraconazole pulse-therapy and local debridement. Conclusions Chromoblastomycosis is reported for the first time from Laos. It carries the danger of bacterial and myiasis superinfection. Leech bites may facilitate infection.This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Causes of non-malarial fever in Laos: a prospective study

Background Because of reductions in the incidence of Plasmodium falciparum malaria in Laos, identifi cation of the causes of fever in people without malaria, and discussion of the best empirical treatment options, are urgently needed. We aimed to identify the causes of non-malarial acute fever in patients in rural Laos. Methods For this prospective study, we recruited 1938 febrile patients, between May, 2008, and December, 2010, at Luang Namtha provincial hospital in northwest Laos (n=1390), and between September, 2008, and December, 2010, at Salavan provincial hospital in southern Laos (n=548). Eligible participants were aged 5–49 years with fever (≥38°C) lasting 8 days or less and were eligible for malaria testing by national guidelines. Findings With conservative defi nitions of cause, we assigned 799 (41%) patients a diagnosis. With exclusion of infl uenza, the top fi ve diagnoses when only one aetiological agent per patient was identifi ed were dengue (156 [8%] of 1927 patients), scrub typhus (122 [7%] of 1871), Japanese encephalitis virus (112 [6%] of 1924), leptospirosis (109 [6%] of 1934), and bacteraemia (43 [2%] of 1938). 115 (32%) of 358 patients at Luang Namtha hospital tested infl uenza PCR-positive between June and December, 2010, of which infl uenza B was the most frequently detected strain (n=121 [87%]). Disease frequency diff ered signifi cantly between the two sites: Japanese encephalitis virus infection (p=0·04), typhoid (p=0·006), and leptospirosis (p=0·001) were more common at Luang Namtha, whereas dengue and malaria were more common at Salavan (all p<0·0001). With use of evidence from southeast Asia when possible, we estimated that azithromycin, doxycycline, ceftriaxone, and ofl oxacin would have had signifi cant effi cacy for 258 (13%), 240 (12%), 154 (8%), and 41 (2%) of patients, respectively. Interpretation Our fi ndings suggest that a wide range of treatable or preventable pathogens are implicated in nonmalarial febrile illness in Laos. Empirical treatment with doxycycline for patients with undiff erentiated fever and negative rapid diagnostic tests for malaria and dengue could be an appropriate strategy for rural health workers in Laos. Funding Wellcome Trust, WHO–Western Pacifi c Region, Foundation for Innovative New Diagnostics, US Centers for Disease Control and Prevention

Heat stress in grapevine: the pros and cons of acclimation

Heatstressisamajorlimitingfactorofgrapevineproduction and quality.Acclimation and recovery are essential to ensure plant survival, and the recovery mechanisms can be independent of the heat response mechanisms.An experimental set up with and without acclimation to heat followed by recovery [stepwise acclimation and recovery (SAR) and stepwise recovery (SR), respectively] was applied to two grapevine varieties,Touriga Nacional (TN),and Trincadeira (TR), with different tolerance to abiotic stress. Major differences were found between leaves of SAR and SR,especially after recovery; in SAR, almost all parameters returned to basal levels while in SR they remained altered. Acclimation led to a swifter and short-term antioxidative response, affecting the plant to a lesser extent than SR. Significant differences were found among varieties: upon stress, TN significantly increased ascorbate and glutathione reduction levels, boosting the cell’s redox-buffering capacity, while TR needed to synthesize both metabolites, its response being insufficient to keep the redox state at working levels.TR was affected by stress for a longer period and the up-regulation pattern of antioxidative stress genes was more obvious. In TN, heat shock proteins were significantly induced, but the canonical heat-stress gene signature was not evident probably because no shutdown of the housekeeping metabolism was needed

Risk of latent tuberculosis infection in children living in households with tuberculosis patients: a cross sectional survey in remote northern Lao People's Democratic Republic

ABSTRACT: BACKGROUND: Tuberculosis is highly prevalent in Laos (289 per 100,000). We evaluated the risk of latent tuberculosis infection (LTBI) among children (0-15 years) living with tuberculosis patients in rural northern Laos. METHODS: In a cross sectional survey of 30 randomly selected villages, 72 tuberculosis patients were traced and their 317 contacts (148 were children) investigated using a questionnaire, a tuberculin skin tests (positive: <= 10mm), a 3-day sputum examination for acid-fast bacilli (AFB), and chest radiography. RESULTS: None of the 148 contact-children received prophylaxis, one had cervical tuberculosis; the risk for LTBI was 31.0%. Awareness of the infectiousness of tuberculosis was low among patients (31%) and their contacts (31%), and risky behavior was common. After multivariate logistic analysis, increased LTBI was found in children with contact with sputum positive adults (OR: 3.3, 95% CI: 1.4-7.7), patients highly positive sputum prior to treatment (AFB <2+; OR: 4.7, 95% CI: 1.7-12.3), and living in ethnic minorities (OR: 5.4, 95% CI: 2.2-13.6). CONCLUSION: The study supports the importance of contact tracing in remote settings with high TB prevalence. Suggestions to improve the children's detection rate, the use of existing guidelines, chemoprophylaxis of contact-children and the available interventions in Laos are discussed. Improving education and awareness of the infectiousness of TB in patients is urgently needed to reduce TB transmissio

Differential physiological response of the grapevine varieties Touriga Nacional and Trincadeira to combined heat, drought and light stress

Worldwide, extensive agricultural losses are attributed to drought, often in combination with heat in Mediterranean climate regions, where grapevine traditionally grows. The available scenarios for climate change suggest increases in aridity in these regions. Under natural conditions plants are affected by a combination of stresses, triggering synergistic or antagonistic physiological, metabolic or transcriptomic responses unique to the combination. However the study of such stresses in a controlled environment can elucidate important mechanisms by allowing the separation of the effects of individual stresses. To gather those effects, cuttings of two grapevine varieties, Touriga Nacional (TN) and Trincadeira (TR), were grown under controlled conditions and subjected to three abiotic stresses (drought – WS, heat – HS and high light – LS) individually and in combination two-by-two (WSHS, WSLS, HSLS) or all three (WSHSLS). Photosynthesis, water status, contents of H2O2, abscisic acid and metabolites of the ascorbate-glutathione cycle were measured in the leaves. Common and distinct response features were identified in the different stress combinations. Photosynthesis was not hindered in TN by LS, while even individual stresses severely affect photosynthesis in TR. Abscisic acid may be implicated in grapevine osmotic responses since it is correlated with tolerance parameters, especially in combined stresses involving drought. Overall, the responses to drought-including treatments were clearly distinct to those without drought. From the specific behaviours of the varieties, it can be concluded that TN shows a higher capacity for heat dissipation and for withstanding high light intensities, indicating better adjustment to warm conditions, provided that water supply is plentifu