FbpA-Dependent biosynthesis of trehalose dimycolate is required for the intrinsic multidrug resistance, cell wall structure, and colonial morphology of Mycobacterium smegmatis

Ligation of mycolic acids to structural components of the mycobacterial cell wall generates a hydrophobic, impermeable barrier that provides resistance to toxic compounds such as antibiotics. Secreted proteins FbpA, FbpB, and FbpC attach mycolic acids to arabinogalactan, generating mycolic acid methyl esters (MAME) or trehalose, generating alpha,alpha'-trehalose dimycolate (TDM; also called cord factor). Our studies of Mycobacterium smegmatis showed that disruption of fbpA did not affect MAME levels but resulted in a 45% reduction of TDM. The fbpA mutant displayed increased sensitivity to both front-line tuberculosis-targeted drugs as well as other broad-spectrum antibiotics widely used for antibacterial chemotherapy. The irregular, hydrophobic surface of wild-type M. smegmatis colonies became hydrophilic and smooth in the mutant. While expression of M. smegmatis fbpA restored defects of the mutant, heterologous expression of the Mycobacterium tuberculosis fbpA gene was less effective. A single mutation in the M. smegmatis FbpA esterase domain inactivated its ability to provide antibiotic resistance. These data show that production of TDM by FbpA is essential for the intrinsic antibiotic resistance and normal colonial morphology of some mycobacteria and support the concept that FbpA-specific inhibitors, alone or in combination with other antibiotics, could provide an effective treatment to tuberculosis and other mycobacterial diseases.     

Cl(-)/HCO(3)(-) exchange is acetazolamide sensitive and activated by a muscarinic receptor-induced [Ca(2+)](i) increase in salivary acinar cells

Large volumes of saliva are generated by transepithelial Cl(-) movement during parasympathetic muscarinic receptor stimulation. To gain further insight into a major Cl(-) uptake mechanism involved in this process, we have characterized the anion exchanger (AE) activity in mouse serous parotid and mucous sublingual salivary gland acinar cells. The AE activity in acinar cells was Na(+) independent, electroneutral, and sensitive to the anion exchange inhibitor DIDS, properties consistent with the AE members of the SLC4A gene family. Localization studies using a specific antibody to the ubiquitously expressed AE2 isoform labeled acini in both parotid and sublingual glands. Western blot analysis detected an approximately 170-kDa protein that was more highly expressed in the plasma membranes of sublingual than in parotid glands. Correspondingly, the DIDS-sensitive Cl(-)/HCO(3)(-) exchanger activity was significantly greater in sublingual acinar cells. The carbonic anhydrase antagonist acetazolamide markedly inhibited, whereas muscarinic receptor stimulation enhanced, the Cl(-)/HCO(3)(-) exchanger activity in acinar cells from both glands. Intracellular Ca(2+) chelation prevented muscarinic receptor-induced upregulation of the AE, whereas raising the intracellular Ca(2+) concentration with the Ca(2+)-ATPase inhibitor thapsigargin mimicked the effects of muscarinic receptor stimulation. In summary, carbonic anhydrase activity was essential for regulating Cl(-)/HCO(3)(-) exchange in salivary gland acinar cells. Moreover, muscarinic receptor stimulation enhanced AE activity through a Ca(2+)-dependent mechanism. Such forms of regulation may play important roles in modulating fluid and electrolyte secretion by salivary gland acinar cells.     

Distribution and abundance of marine turtles in the Socialist Republic of Viet Nam

To establish baseline data on the distribution, abundance and threats to marine turtles in Viet Nam we conducted surveys with local fishers, community members and provincial Ministry of Fisheries staff from 17 of Viet Nam’s 29 coastal provinces. These data indicate that five species of marine turtle reside in Viet Nam’s waters (loggerhead, olive ridley, leatherback, green and hawksbill turtles), and four species nest on Viet Nam’s beaches (all of the above except the loggerhead turtle). It is evident from these data that significant declines have occurred in both foraging and nesting populations of all five marine turtle species found in Viet Nam. The greatest current threats to marine turtle populations in Viet Nam are habitat degradation, the accidental and opportunistic of turtles capture by fishers and the direct take of nesting females and their eggs. Successful conservation efforts have been made in recent years through collaboration between international Non Government Organisations and several Vietnamese Government Ministries. Continued success of these projects and the development and implementation of marine conservation policy will depend upon building awareness among Government employees, fishers and the general public about marine turtle biology, ecology, and the need to protect them.     

Inhibition of soluble epoxide hydrolase activity by compounds isolated from the aerial parts of Glycosmis stenocarpa

The aim of this study is to search for soluble epoxide hydrolase (sEH) inhibitors from natural plants, bioassay-guided fractionation of lipophilic n-hexane and chloroform layers of an extract of the aerial parts of Glycosmis stenocarpa led to the isolation of 12 compounds (1–12) including murrayafoline-A (1), isomahanine (2), bisisomahanine (3), saropeptate (4), (24?S)-ergost-4-en-3,6-dione (5), stigmasta-4-en-3,6-dion (6), stigmast-4-en-3-one (7), β-sitosterol (8), 24-methylpollinastanol (9), trans-phytol (10), neosarmentol III (11) and (+)-epiloliolide (12). Their structures were elucidated on the basis of spectroscopic data. Among them, neosarmentol III (11) was isolated from nature for the first time. All the isolated compounds were evaluated for their inhibitory activity against sEH. Among isolated carbazole-type compounds, isomahanine (2) and bisisomahanine (3) were identified as a potent inhibitor of sEH, with IC₅₀ values of 22.5?±?1.7 and 7.7?±?1.2?µM, respectively. Moreover, the inhibitory action of 2 and 3 represented mixed-type enzyme inhibition.     

<Emphasis Type="Italic">Typhonium stigmatilobatum</Emphasis> (<Emphasis Type="Italic">Araceae</Emphasis> tribe <Emphasis Type="Italic">Areae</Emphasis>), a new species from Vietnam

Summary   Typhonium stigmatilobatum V. D. Nguyen, a new species from Vietnam, is described and illustrated.     

Activation of oxidative metabolism of granulocytes and monocytes by IGG-coated platelets from patients with thrombocytopenia

We have previously shown that monoclonal anti-T cell antibodies bound to their specific targets can trigger the activation of monocyte/macrophage oxidative metabolism through an Fc receptor-mediated interaction. The present study demonstrates that IgG coated platelets from patients with thrombocytopenia-associated diseases can induce a similar respiratory burst activation in polymorphonuclear and mononuclear phagocytes from normal individuals. The intensity of the oxidative reaction as measured by luminol-dependent chemiluminescence is in close correlation with the level of surface-bound IgG molecules as determined by a radioactive anti-immunoglobulin assay. This new methodology to evaluating IgG fixed on human platelets by their capacity to trigger the generation of highly reactive oxygen species by granulocytes and monocytes has also suggested a new mechanism in the genesis of thrombocytopenia associated with autoimmune diseases.     

Evolutionary origins of taro (Colocasia esculenta) in Southeast Asia

As an ancient clonal root and leaf crop, taro (Colocasia esculenta, Araceae) is highly polymorphic with uncertain genetic and geographic origins. We explored chloroplast DNA diversity in cultivated and wild taros, and closely related wild taxa, and found cultivated taro to be polyphyletic, with tropical and temperate clades that appear to originate in Southeast Asia sensu lato. A third clade was found exclusively in wild populations from Southeast Asia to Australia and Papua New Guinea. Our findings do not support the hypothesis of taro domestication in Papua New Guinea, despite archaeological evidence for early use or cultivation there, and the presence of apparently natural wild populations in the region (Australia and Papua New Guinea).     

Squash trypsin inhibitors from Momordica cochinchinensis exhibit an atypical macrocyclic structure

Three trypsin inhibitors (TIs), from the seeds of the squash Momordica cochinchinensis (MCo), have been isolated and purified using gel filtration, ion exchange chromatography, and reverse-phase HPLC. Their sequences could be determined only after proteolytic cleavages. In the case of MCoTI-I and -II, it was shown that their polypeptide backbones are cyclic, a structure that has never been described in squash TIs. They contain 34 amino acid residues with 3 disulfide bridges and measured molecular masses of 3453.0 and 3480.7, respectively. They are the largest known macrocyclic peptides containing disulfide bridges. Their sequences show strong homology to other squash TIs, suggesting a similar three-dimensional structure and an analogous mechanism of action. A model of MCoTI-II was constructed by analogy to the crystal structure of the complex between bovine trypsin and CMTI-I, indicating that the linker connecting the two termini is flexible and does not impose significant geometrical constraints. This flexibility allows an Asp-Gly peptide bond rearrangement to occur in this region, giving rise to two isoforms of MCoTI-II. Although the importance of cyclization is not clear, it might confer increased stability and resistance to proteolysis. A minor species, MCoTI-III, was also characterized as containing 30 amino acid residues with a molecular mass of 3379.6. This component possesses a linear backbone with a blocked N-terminus. MCoTIs represent interesting candidates for drug design, either by changing their specificity of inhibition or by using their structure as natural scaffolds bearing new binding activities.     

Diagnoses and factors associated with medical evacuation and return to duty among nonmilitary personnel participating in military operations in Iraq and Afghanistan

Background

Nonmilitary personnel play an increasingly critical role in modern wars. Stark differences exist between the demographic characteristics, training and missions of military and nonmilitary members. We examined the differences in types of injury and rates of returning to duty among nonmilitary and military personnel participating in military operations in Iraq and Afghanistan.

Methods

We collected data for nonmilitary personnel medically evacuated from military operations in Iraq and Afghanistan between 2004 and 2007. We compared injury categories and return-to-duty rates in this group with previously published data for military personnel and identified factors associated with return to duty.

Results

Of the 2155 medically evacuated nonmilitary personnel, 74.7% did not return to duty. War-related injuries in this group accounted for 25.6% of the evacuations, the most common causes being combat-related injuries (55.4%) and musculoskeletal/spinal injuries (22.9%). Among individuals with non–war-related injuries, musculoskeletal injuries accounted for 17.8% of evacuations. Diagnoses associated with the highest return-to-duty rates in the group of nonmilitary personnel were psychiatric diagnoses (15.6%) among those with war-related injuries and noncardiac chest or abdominal pain (44.0%) among those with non–war-related injuries. Compared with military personnel, nonmilitary personnel with war-related injuries were less likely to return to duty (4.4% v. 5.9%, p = 0.001) but more likely to return to duty after non–war-related injuries (32.5% v. 30.7%, p = 0.001).

Interpretation

Compared with military personnel, nonmilitary personnel were more likely to be evacuated with non–war-related injuries but more likely to return to duty after such injuries. For evacuations because of war-related injuries, this trend was reversed.In modern warfare, injuries sustained in combat have never been the leading source of attrition among soldiers. In World War I, World War II and the Korean War, respiratory and infectious diseases were the top reasons for hospital admissions among service members. By the Vietnam Conflict, non-battle injuries had supplanted respiratory illness as the leading cause of hospital admissions and have remained the leading cause ever since.^1,2The principal causes for medical evacuation of military personnel from US operations in Iraq and Afghanistan were recently described in a large four-year epidemiologic study.³ In descending order, the leading reasons were musculoskeletal conditions, combat-related injuries, neurologic symptoms and psychiatric disorders; the last category surpassed combat-related injuries as the number two reason in the latter half of both engagements. However, nonmilitary personnel were not included in that study. Over the past three years, nonmilitary members, including US Department of Defense civilians, private contractors and diplomats, have comprised about 50% of personnel serving in Iraq and about two-thirds of those serving in Afghanistan.^4,5Several reasons may explain why the types of injury and the return-to-duty rates differ between military and nonmilitary personnel. First, the motivations for overseas deployment might differ between the groups. Whereas some civilian personnel (e.g., diplomats) may be assigned to positions in Iraq and Afghanistan, virtually all private contractors volunteer for their jobs. In contrast, most military members have little choice in their deployment. Second, military and nonmilitary members assigned to war zones have different occupational specialties, living conditions and regulations to which they must adhere. Especially for junior military personnel, jobs tend to be more dangerous, living environments more austere and regulations more stringent. Finally, unlike military personnel, who are paid regardless of deployment status, most contractors’ pay is contingent upon continued employment in theatres of operation. In addition, nonmilitary personnel are generally compensated with higher salaries than service members in comparable occupational specialties.In civilian cohorts, many of these factors have been shown to influence return-to-work rates in a variety of contexts. Studies of the effect of financial compensation on work status after injury have generally shown a direct correlation between return-to-work rates and higher income levels.^6,7 Similar associations have also been found between return-to-work rates and job satisfaction and coping mechanisms, factors that may be influenced by work conditions and perceived control over one’s environment.^8–10The objectives of our study were threefold: to ascertain whether the reasons for medical evacuation from military operations differed between military and nonmilitary personnel; to determine whether return-to-duty rates differed between the two groups; and to identify factors that influence return-to-duty rates among nonmilitary members.