Antimalarial and cytotoxic quassinoids from the roots of Brucea javanica

Two new quassinoids, brujavanol A (1) and brujavanol B (2), along with five known quassinoids (3–7), were isolated from the roots of Brucea javanica. Their structures were elucidated by spectroscopic methods. The antimalarial and cytotoxic activities of the isolated compounds were also assessed. Compounds 1 and 2 exhibited significant in vitro cytotoxicity against human oral cavity cancer (KB) cells with IC₅₀ values of 1.30 and 2.36 μg/ml, respectively, whereas compound 3 showed excellent antiplasmodial activity against the Plasmodium falciparum strains, K1 (IC₅₀ = 0.58 μg/ml).     

The platelet amyloid precursor protein ratio as a diagnostic marker for Alzheimer’s disease in Thai patients

The platelet amyloid precursor protein (APP) ratio has recently been shown to be a promising diagnostic marker for Alzheimer’s disease (AD). To evaluate its usefulness in Thai patients, platelet APP was analyzed by immunoblotting. The APP ratio was calculated as the ratio of the combined band density of the 120-kD and 130-kD isoforms compared to that of the 110-kD isoform. The mean ages (and ranges) of 27 normal and 13 AD-affected subjects were 68.3 (60–84) and 79.3 (70–97) years, respectively. The Thai Mental State Examination (TMSE) scores demonstrated that the AD patients had significantly poorer cognitive functions than the normal subjects, with mean TMSE scores of 20.3 and 27.6 (maximum score of 30 points), respectively (p < 0.05). The platelet APP ratios of the AD patients were significantly lower than those of normal subjects: values (mean ± standard deviation) were 7.32 ± 1.29 and 9.13 ± 3.00, respectively (p < 0.05) for AD patients and normal subjects. However, the ranges of the APP ratios from both groups markedly overlapped, which precluded the establishment of a cutoff level to differentiate between the AD and normal subjects. In addition, no significant correlations were observed between the platelet APP ratio and the TMSE score or between the APP ratio and the serum cholesterol in this study, in contrast to previous reports.     

Rapid determination of viral RNA sequences in mosquitoes collected in the field

A method for rapid determination of viral RNA sequences (RDV) was applied to homogenates of Aedes aegypti collected in Thailand in an area in which dengue fever (dengue hemorrhagic fever) is endemic, using the mosquito cell line C6/36. Nucleic acid sequences of dengue virus type 4 and cell fusing agent virus were detected. This RDV method has the potential to become a standard method for detection of both known and newly emerging, unknown mosquito-borne viruses.     

A case of successful treatment of severe COVID‐19 pneumonia with favipiravir and tocilizumab in post–kidney transplant recipient

We report a case of COVID‐19 in kidney transplant patient in Thailand. A 58‐year‐old 2 years post–kidney transplant recipient, with maintenance immunosuppression of tacrolimus, mycophenolate mofetil (MMF), and prednisolone, presented with acute diarrhea which followed by fever on day 12. Symptoms of pneumonia together with lymphopenia from complete blood count were developed on day 7 after onset of fever with the x‐ray finding of bilateral multifocal patchy infiltration. COVID‐19 infection has been confirmed by reverse real‐time polymerase chain reaction (PCR) in nasal swab as well as found in stool. Darunavir together with ritonavir, hydroxychloroquine, azithromycin, and favipiravir was initiated on the first day of admission at primary hospital. Patient has been transferred to our hospital on day 2 of admission in which tacrolimus together with MMF was discontinued. High‐flow nasal cannula oxygen therapy was required on days 4‐5 of hospitalization. Tocilizumab was administered after rising of serum IL‐6 level. Symptoms of pneumonia were improved in which no oxygen treatment required from day 10 of hospitalization. Drug interaction between tacrolimus and anti‐viral treatment leads to severely high level of tacrolimus which caused reversible acute kidney injury (AKI) after supportive treatment.     

A Peptide Inhibitor Derived from the Conserved Ectodomain Region of DENV Membrane (M) Protein with Activity Against Dengue Virus Infection

Dengue virus (DENV) infection is a public health problem worldwide; thus, the development of a vaccine and anti‐DENV drugs is urgently needed. It has been observed that low levels of viremia in DENV‐infected individuals are associated with mild disease outcomes; therefore, reduction of DENV load should offer therapeutic benefits. Disruption of protein–protein interactions on the surface of DENV by a peptide that mimics part of its structural protein may affect stability of the virion structure and inhibit viral entry into host cells. To test this hypothesis, we generated a novel peptide inhibitor that mimics the conserved ectodomain region of DENV membrane (M) protein, MLH40 peptide, for DENV inhibition assays. MLH40 inhibited all four serotypes of the virus (DENV1–4) at half maximal inhibition concentration of 24–31 μm . MLH40 at 100 μm blocked DENV2 attachment to cells by 80%. The inhibitory activity of MLH40 against DENV was consistently observed with different cell types, including Vero, A549, and Huh7 cells. Prediction of MLH40 binding by a molecular docking program indicated that its N‐terminal loop may interact with DENV envelope (E) proteins and alter their dimer conformation. Thus, MLH40 may serve as a lead‐peptide inhibitor for the development of an anti‐DENV drug.     

Improvement of vascular function by chronic administration of a cyclo-oxygenase inhibitor in cholesterol-fed rabbits

1. Atherosclerotic cardio- and cerebrovascular disease is a leading cause of mortality in Western countries. Aspirin-like drugs are widely used to prevent and treat these occlusive cardio- and cerebrovascular diseases. The beneficial effects of these drugs have been largely attributed to inhibition of platelet cyclo-oxygenase activity and thromboxane (TX) A2 production. We investigated the effect of an aspirin-like drug, namely indomethacin, on endothelial function, plaque and platelet aggregation and the formation of vasoactive substances during the development of atherosclerosis in cholesterol-fed rabbits. 2. Rabbits were fed 1% cholesterol (n = 8), 1% cholesterol plus 25 mg/day indomethacin (n = 8) or normal rabbit chow (control group; n = 8) for 12 weeks. Urinary excretion rates of 2,3-dinor-TXB2, 6-keto-prostaglandin (PG) F1alpha, 8-iso-PGF2alpha and nitrate were analysed at the beginning of dietary intervention and at 4 weekly intervals thereafter. At the end of the study period, platelet aggregation, aortic plaque formation and endothelium-dependent and -independent vascular functions of isolated aortic rings ex vivo were assessed. 3. Compared with control, in the cholesterol-fed group, urinary 2,3-dinor-TXB2, 6-keto-PGF1alpha and 8-iso-PGF2alpha excretion and platelet aggregation were significantly increased (P < 0.05), but urinary excretion of nitrate was decreased (P < 0.05). Treatment with indomethacin significantly reduced platelet aggregation, urinary 2,3-dinor-TXB2, 6-keto-PGF1alpha and 8-iso-PGF2alpha excretion (P < 0.05 vs the cholesterol-fed group) and attenuated the reduction in urinary nitrate excretion. 4. Cholesterol feeding progressively increased aortic intimal thickening and impaired endothelium-dependent vasodilator function (P < 0.05 vs control), whereas indomethacin partially prevented aortic plaque formation and restored endothelium-dependent vasodilation (P < 0.05 vs the cholesterol-fed group). 5. The present study demonstrates that indomethacin reduces the progression of atherosclerotic lesions and improves endothelium-mediated vascular responses ex vivo in cholesterol-fed rabbits. The beneficial effects of indomethacin may be due to its ability to prevent the elevation of platelet aggregation, TXA2 (measured as urinary 2,3-dinor-TXB2 excretion) and 8-iso-PGF2alpha formation and to retard the decrease in endogenous nitric oxide synthesis (assessed as urinary excretion of nitrate). Despite indomethacin treatment leading to the suppression of prostacyclin biosynthesis (assessed as urinary 6-keto-PGF1alpha excretion), according to our data, indomethacin appears to preserve endothelial function.     

On-line Hemodiafiltration in Southeast Asia: A Three-year Prospective Study of a Single Center

Abstract: Growing evidence suggests the superiority of on-line hemodiafiltration (HDF) compared with the conventional hemodialysis technique in many aspects; however, on-line HDF is still not used worldwide, including in Southeast Asia. The purpose of this study is to compare various clinical outcomes between on-line HDF and high-flux hemodialysis (HFHD). This was a single-center three-year prospective observational study that demonstrated the clinical parameters after switching from HFHD to on-line HDF in 22 HDF patients, whose average age was 58.1 ± 13.3 years. The incidence of intradialytic undesired events, including hypotension, decreased and an apparent increase in appetite and an improvement in overall well-being were recorded by most patients after switching to on-line HDF. The data for dry weight, body mass index, and normalized protein nitrogen appearance, which represent nutritional status, showed a significant improvement while still maintaining a satisfactory albumin level. The adequacy in terms of urea reduction ratio significantly increased. The serum predialysis β₂-microglobulin levels were reduced by 25.7% from 31.1 ± 3.1 to 23.1 ± 4.8 mg/L (P < 0.05) at six months and remained constant during the three years of follow-up. The patients' lipid profile was well controlled, and the mean C-reactive protein value was still maintained in the normal range. In conclusion, our three-year experience showed that on-line HDF is a well-tolerated treatment with a lower incidence of intradialytic undesired events. The potential benefits may include the effective removal of higher molecular weight uremic toxins and an improved nutritional status, along with a low inflammatory state.     

Heterosexual transmission of novel CRF01_AE and subtype B recombinant forms of HIV type 1 in northern Thailand

The increased proportion of CRFO1_AE/subtype B recombinant infections among injecting drug users raised a concern that such recombinant forms may also spread in a heterosexual population in Thailand. Using the BootScan method, we reanalyzed pol gene sequences among 114 heterosexually infected individuals in northern Thailand, who were tested for a drug-resistance genotype between July 2000 and July 2001. Two individuals were suspected of carrying a recombinant HIV-1. Thus we analyzed a nearly full-length HIV genome in the two individuals and their spouses. An identical recombinant form of CRF01_AE and subtype B was found in one couple, indicating that this recombinant virus was heterosexually transmitted. Interestingly, this recombinant form had multiple breakpoints in the core protein of Gag and both infected individuals had a high CD4+ cell count without antiretroviral therapy. CRFO1/subtype B recombinant forms exist in a heterosexual population in northern Thailand. Some recombinant virus may be associated with a slow rate of HIV disease progression.     

Regional citrate anticoagulation reduces polymorphonuclear cell degranulation in critically ill patients treated with continuous venovenous hemofiltration

Citrate which chelates ionized calcium can be used as regional anticoagulation in continuous venovenous hemofiltration (CVVH). This is the first study conducted to examine the potentially additive benefit effect of regional citrate anticoagulation (RCA) on polymorphonuclear (PMN) cell degranulation of myeloperoxidase (MPO) and cytokines production in patients with critically acute kidney injury (AKI) undergoing CVVH treatment. This prospective randomized controlled trial was conducted in 20 critically ill patients with AKI who underwent CVVH. The patients were randomized into regional citrate group (n=10) and heparin group (n=10). The pre-dilution CVVH with polyethersulfone dialyzers were utilized in both groups. The levels of pre-filter and post-filter MPO as well as inflammatory and anti-inflammatory cytokines were measured at baseline, 6h, and 24 h after initiating CVVH. In the heparin group, the post-filter serum MPO levels were significantly higher than the pre-filter (median 49.0 vs. 60.5 ng/mL, P<0.05) at 6 h. There were no significant differences between pre- and post-dialyzer MPO levels in the citrate group. Citrate could significantly decrease systemic pre-filter serum MPO levels from baseline at 6 h (median 43.5 vs. 17.3 ng/mL, P<0.01) as well as IL-8 levels (P<0.05) whereas heparin provided only significant TNF-α reduction (P<0.05). The CVVH circuit survival in the citrate group was longer than the heparin group. In conclusion, citrate, utilized as a regional anticoagulant in CVVH, can reduce both membrane bioincompatibility-induced and systemic oxidative stress and inflammation, and can prolong CVVH circuit survival time.     

Plasma neutrophil gelatinase-associated lipocalin predicts recovery from acute kidney injury following community-acquired pneumonia

Although plasma neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker for early detection of acute kidney injury, its ability to predict recovery is unknown. Using RIFLE criteria to define kidney injury, we tested whether higher plasma NGAL concentrations on the first day of RIFLE-F would predict failure to recover in a post hoc analysis of a multicenter, prospective, cohort study of patients with community-acquired pneumonia. Recovery was defined as alive and not requiring renal replacement therapy during hospitalization or having a persistent RIFLE-F classification at hospital discharge. Median plasma NGAL concentrations were significantly lower among the 93 of 181 patients who recovered. Plasma NGAL alone predicted failure to recover with an area under the receiver operating characteristic curve of 0.74. A clinical model using age, serum creatinine, pneumonia severity, and nonrenal organ failure predicted failure to recover with area under the curve of 0.78. Combining this clinical model with plasma NGAL concentrations did not improve prediction. The reclassification of risk of renal recovery, however, significantly improved by 17% when plasma NGAL was combined with the clinical model. Thus, in this cohort of patients with pneumonia-induced severe acute kidney injury, plasma NGAL appears to be a useful biomarker for predicting renal recovery.