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Fulltext COX-2 inhibitors: a potential target for drug therapy in the management of colorectal cancer

Ryan ARA, Rosita ARA, Kamarul AK, Qureshi A

Med J Malaysia, 1999 Sep;54(3):293-5.
PMID: 11045053

Colorectal cancer is currently the third most common cancer in Malaysia. Elevated expression of COX-2, an induced cyclooxygenase isoenzyme, has been seen in colonic adenomas and colorectal carcinoma. There is evidence that inhibition of this COX-2 can decrease the risk of colorectal cancer. Selective COX-2 inhibitors may have a role in reducing the risk of colorectal cancer in high-risk individuals.
Fulltext Rewinding the waves: tracking underwater signals to their source

Kadri U, Crivelli D, Parsons W, Colbourne B, Ryan A

Sci Rep, 2017 10 24;7(1):13949.
PMID: 29066744 DOI: 10.1038/s41598-017-14177-3

Analysis of data, recorded on March 8th 2014 at the Comprehensive Nuclear-Test-Ban Treaty Organisation's hydroacoustic stations off Cape Leeuwin Western Australia, and at Diego Garcia, reveal unique pressure signatures that could be associated with objects impacting at the sea surface, such as falling meteorites, or the missing Malaysian Aeroplane MH370. To examine the recorded signatures, we carried out experiments with spheres impacting at the surface of a water tank, where we observed almost identical pressure signature structures. While the pressure structure is unique to impacting objects, the evolution of the radiated acoustic waves carries information on the source. Employing acoustic-gravity wave theory we present an analytical inverse method to retrieve the impact time and location. The solution was validated using field observations of recent earthquakes, where we were able to calculate the eruption time and location to a satisfactory degree of accuracy. Moreover, numerical validations confirm an error below 0.02% for events at relatively large distances of over 1000 km. The method can be developed to calculate other essential properties such as impact duration and geometry. Besides impacting objects and earthquakes, the method could help in identifying the location of underwater explosions and landslides.
Fulltext Exploring Attitudes Toward Pre-Exposure Prophylaxis for HIV Prevention Prior to Implementation Among Female Sex Workers in Malaysia: Results from a Qualitative Study

Foley S, Keene DE, Shrestha R, Brown SE, Gautam K, Sutherland RA, et al.

Patient Prefer Adherence, 2024;18:797-807.
PMID: 38595805 DOI: 10.2147/PPA.S413423

INTRODUCTION: Pre-exposure prophylaxis (PrEP) is an effective method for prevention of HIV transmission. Female sex workers (FSW) in Malaysia are at substantially increased risk of acquiring HIV compared to the general female population, yet little is known about this population's current HIV prevention practices or acceptance of PrEP. This study aims to inform the culturally relevant implementation of PrEP through the qualitative exploration of (1) the potential need for PrEP in this population and (2) the factors that determine FSW willingness to use oral PrEP.
METHODS: In-depth, semi-structured interviews (n = 30) were conducted with FSW in English, Malay, or Tamil. Transcribed and translated interviews were analyzed using a grounded theory approach.
RESULTS: FSW express positive interest in PrEP but prefer it as a supplement to condoms, not a replacement. Perceived challenges to PrEP use include cost, adherence, and side effects.
CONCLUSION: The findings suggest that in combination with condom use, PrEP may be an acceptable method of HIV prevention. Effective PrEP rollout may also include condom promotion using a peer-driven model, cost subsidies, and sex work harm reduction and empowerment components.
Fulltext Emerging Two-Dimensional Crystallization of Cucurbit[8]uril Complexes: From Supramolecular Polymers to Nanofibers

Barrio JD, Liu J, Brady RA, Tan CSY, Chiodini S, Ricci M, et al.

J Am Chem Soc, 2019 09 11;141(36):14021-14025.
PMID: 31422657 DOI: 10.1021/jacs.9b07506

The binding of imidazolium salts to cucurbit[8]uril, CB[8], triggers a stepwise self-assembly process with semiflexible polymer chains and crystalline nanostructures as early- and late-stage species, respectively. In such a process, which involves the crystallization of the host-guest complexes, the guest plays a critical role in directing self-assembly toward desirable morphologies. These include platelet-like aggregates and two-dimensional (2D) fibers, which, moreover, exhibit viscoelastic and lyotropic properties. Our observations provide a deeper understanding of the self-assembly of CB[8] complexes, with fundamental implications in the design of functional 2D systems and crystalline materials.
Fulltext Chemical Composition and Antioxidant, Antimicrobial, and Anti-Inflammatory Properties of Origanum compactum Benth Essential Oils from Two Regions: In Vitro and In Vivo Evidence and In Silico Molecular Investigations

Al-Mijalli SH, Mrabti NN, Ouassou H, Sheikh RA, Assaggaf H, Bakrim S, et al.

Molecules, 2022 Oct 28;27(21).
PMID: 36364152 DOI: 10.3390/molecules27217329

The purposes of this investigatory study were to determine the chemical composition of the essential oils (EOs) of Origanum compactum from two Moroccan regions (Boulemane and Taounate), as well as the evaluation of their biological effects. Determining EOs' chemical composition was performed by a gas chromatography-mass spectrophotometer (GC-MS). The antioxidant activity of EOs was evaluated using free radical scavenging ability (DPPH method), fluorescence recovery after photobleaching (FRAP), and lipid peroxidation inhibition assays. The anti-inflammatory effect was assessed in vitro using the 5-lipoxygenase (5-LOX) inhibition test and in vivo using the carrageenan-induced paw edema model. Finally, the antibacterial effect was evaluated against several strains using the disk-diffusion assay and the micro-dilution method. The chemical constituent of O. compactum EO (OCEO) from the Boulemane zone is dominated by carvacrol (45.80%), thymol (18.86%), and α-pinene (13.43%). However, OCEO from the Taounate zone is rich in 3-carene (19.56%), thymol (12.98%), and o-cymene (11.16%). OCEO from Taounate showed higher antioxidant activity than EO from Boulemane. Nevertheless, EO from Boulemane considerably inhibited 5-LOX (IC50 = 0.68 ± 0.02 µg/mL) compared to EO from Taounate (IC50 = 1.33 ± 0.01 µg/mL). A similar result was obtained for tyrosinase inhibition with Boulemane EO and Taounate EO, which gave IC50s of 27.51 ± 0.03 μg/mL and 41.83 ± 0.01 μg/mL, respectively. The in vivo anti-inflammatory test showed promising effects; both EOs inhibit and reduce inflammation in mice. For antibacterial activity, both EOs were found to be significantly active against all strains tested in the disk-diffusion test, but O. compactum EO from the Boulemane region showed the highest activity. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) for O. compactum EO from the Boulemane region ranged from 0.06 to 0.25% (v/v) and from 0.15 to 0.21% (v/v) for O. compactum from the Taounate region. The MBC/MIC index revealed that both EOs exhibited remarkable bactericidal effects.
Two centuries of biodiversity discovery and loss in Singapore

Chisholm RA, Kristensen NP, Rheindt FE, Chong KY, Ascher JS, Lim KKP, et al.

Proc Natl Acad Sci U S A, 2023 Dec 19;120(51):e2309034120.
PMID: 38079550 DOI: 10.1073/pnas.2309034120

There is an urgent need for reliable data on the impacts of deforestation on tropical biodiversity. The city-state of Singapore has one of the most detailed biodiversity records in the tropics, dating back to the turn of the 19th century. In 1819, Singapore was almost entirely covered in primary forest, but this has since been largely cleared. We compiled more than 200 y of records for 10 major taxonomic groups in Singapore (>50,000 individual records; >3,000 species), and we estimated extinction rates using recently developed and novel statistical models that account for "dark extinctions," i.e., extinctions of undiscovered species. The estimated overall extinction rate was 37% (95% CI [31 to 42%]). Extrapolating our Singapore observations to a future business-as-usual deforestation scenario for Southeast Asia suggests that 18% (95% CI [16 to 22%]) of species will be lost regionally by 2100. Our extinction estimates for Singapore and Southeast Asia are a factor of two lower than previous estimates that also attempted to account for dark extinctions. However, we caution that particular groups such as large mammals, forest-dependent birds, orchids, and butterflies are disproportionately vulnerable.
Temporal population variability in local forest communities has mixed effects on tree species richness across a latitudinal gradient

Fung T, Chisholm RA, Anderson-Teixeira K, Bourg N, Brockelman WY, Bunyavejchewin S, et al.

Ecol Lett, 2020 Jan;23(1):160-171.
PMID: 31698546 DOI: 10.1111/ele.13412

Among the local processes that determine species diversity in ecological communities, fluctuation-dependent mechanisms that are mediated by temporal variability in the abundances of species populations have received significant attention. Higher temporal variability in the abundances of species populations can increase the strength of temporal niche partitioning but can also increase the risk of species extinctions, such that the net effect on species coexistence is not clear. We quantified this temporal population variability for tree species in 21 large forest plots and found much greater variability for higher latitude plots with fewer tree species. A fitted mechanistic model showed that among the forest plots, the net effect of temporal population variability on tree species coexistence was usually negative, but sometimes positive or negligible. Therefore, our results suggest that temporal variability in the abundances of species populations has no clear negative or positive contribution to the latitudinal gradient in tree species richness.
Fulltext Latitudinal patterns in stabilizing density dependence of forest communities

Hülsmann L, Chisholm RA, Comita L, Visser MD, de Souza Leite M, Aguilar S, et al.

Nature, 2024 Mar;627(8004):564-571.
PMID: 38418889 DOI: 10.1038/s41586-024-07118-4

Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species1,2, a phenomenon known as conspecific negative density dependence (CNDD)3. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests4,5, which increases community stabilization, species coexistence and the diversity of local tree species6,7. Previous analyses supporting such a latitudinal gradient in CNDD8,9 have suffered from methodological limitations related to the use of static data10-12. Here we present a comprehensive assessment of latitudinal CNDD patterns using dynamic mortality data to estimate species-site-specific CNDD across 23 sites. Averaged across species, we found that stabilizing CNDD was present at all except one site, but that average stabilizing CNDD was not stronger toward the tropics. However, in tropical tree communities, rare and intermediate abundant species experienced stronger stabilizing CNDD than did common species. This pattern was absent in temperate forests, which suggests that CNDD influences species abundances more strongly in tropical forests than it does in temperate ones13. We also found that interspecific variation in CNDD, which might attenuate its stabilizing effect on species diversity14,15, was high but not significantly different across latitudes. Although the consequences of these patterns for latitudinal diversity gradients are difficult to evaluate, we speculate that a more effective regulation of population abundances could translate into greater stabilization of tropical tree communities and thus contribute to the high local diversity of tropical forests.
Assessing the spatial scale of synchrony in forest tree population dynamics

Chisholm RA, Fung T, Anderson-Teixeira KJ, Bourg NA, Brockelman WY, Bunyavejchewin S, et al.

Proc Biol Sci, 2024 Nov;291(2035):20240486.
PMID: 39564678 DOI: 10.1098/rspb.2024.0486

Populations of forest trees exhibit large temporal fluctuations, but little is known about the synchrony of these fluctuations across space, including their sign, magnitude, causes and characteristic scales. These have important implications for metapopulation persistence and theoretical community ecology. Using data from permanent forest plots spanning local, regional and global spatial scales, we measured spatial synchrony in tree population growth rates over sub-decadal and decadal timescales and explored the relationship of synchrony to geographical distance. Synchrony was high at local scales of less than 1 km, with estimated Pearson correlations of approximately 0.6-0.8 between species' population growth rates across pairs of quadrats. Synchrony decayed by approximately 17-44% with each order of magnitude increase in distance but was still detectably positive at distances of 100 km and beyond. Dispersal cannot explain observed large-scale synchrony because typical seed dispersal distances (<100 m) are far too short to couple the dynamics of distant forests on decadal timescales. We attribute the observed synchrony in forest dynamics primarily to the effect of spatially synchronous environmental drivers (the Moran effect), in particular climate, although pests, pathogens and anthropogenic drivers may play a role for some species.