Camptotheca acuminata 10‐hydroxycamptothecin O‐methyltransferase: an alkaloid biosynthetic enzyme co‐opted from flavonoid metabolism

The medicinal plant Camptotheca acuminata accumulates camptothecin, 10‐hydroxycamptothecin, and 10‐methoxycamptothecin as its major bioactive monoterpene indole alkaloids. Here, we describe identification and functional characterization of 10‐hydroxycamptothecin O‐methyltransferase (Ca10OMT), a member of the Diverse subclade of class II OMTs. Ca10OMT is highly active toward both its alkaloid substrate and a wide range of flavonoids in vitro and in this way contrasts with other alkaloid OMTs in the subclade that only utilize alkaloid substrates. Ca10OMT shows a strong preference for the A‐ring 7‐OH of flavonoids, which is structurally equivalent to the 10‐OH of 10‐hydroxycamptothecin. The substrates of other alkaloid OMTs in the subclade bear little similarity to flavonoids, but the 3‐D positioning of the 7‐OH, A‐ and C‐rings of flavonoids is nearly identical to the 10‐OH, A‐ and B‐rings of 10‐hydroxycamptothecin. This structural similarity likely explains the retention of flavonoid OMT activity by Ca10OMT and also why kaempferol and quercetin aglycones are potent inhibitors of its 10‐hydroxycamptothecin activity. The catalytic promiscuity and strong inhibition of Ca10OMT by flavonoid aglycones in vitro prompted us to investigate the potential physiological roles of the enzyme in vivo. Based on its regioselectivity, kinetic parameters and absence of 7‐OMT flavonoids in vivo, we conclude that the major and likely only substrate of Ca10OMTin vivo is 10‐hydroxycamptothecin. This is likely accomplished by Ca10OMT being kept spatially separated at the tissue levels from potentially inhibitory flavonoid aglycones, and flavonoid aglycones being rapidly glycosylated to non‐inhibitory flavonoid glycosides.     

A new Chondrostoma species from the Büyük Menderes River Basin,Turkey (Teleostei: Cyprinidae)

In a study of the fishes of the Büyük Menderes River Basin, Aegean region of Turkey, two populations of Chondrostoma were found which showed clearly distinctive characters: the population from the Upper B. Menderes (I??kl? Lake) was attributed to C. meandrense Elvira, 1987, while the population from the Çine Stream in the Lower B. Menderes River basin proved to be a hitherto undescribed species: Chondrostoma turnai sp. n. Altogether 24 metric and 7 meristic parameters were compared. The new species is distinguished from C. meandrense and all other cogeners by a combination of the number of lateral line scales, the number of scale rows between the lateral line and the dorsal-fin origin, the number of scale rows of the lateral line and pelvic-fin origin, and the number of gill rakers on the first gill arch.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:811C213D-BEDD-4C8C-AE57-BFFA7964781A     

Complement component 1, q subcomponent binding protein is a marker for proliferation in breast cancer

Complement component 1, q subcomponent binding protein (C1QBP), is a multi-compartmental protein with higher mRNA expression reported in breast cancer tissues. This study evaluated the association between immunohistochemical expression of the C1QBP protein in breast cancer tissue microarrays (TMAs) and clinicopathological parameters, in particular tumor size. In addition, an in vitro study was conducted to substantiate the breast cancer TMA findings. Breast cancer TMAs were constructed from pathological specimens of patients diagnosed with invasive ductal carcinoma. C1QBP protein and proliferating cell nuclear antigen (PCNA) immunohistochemical analyses were subsequently performed in the TMAs. C1QBP immunostaining was detected in 131 out of 132 samples examined. The C1QBP protein was predominantly localized in the cytoplasm of the breast cancer cells. Univariate analysis revealed that a higher C1QBP protein expression was significantly associated with older patients (P = 0.001) and increased tumor size (P = 0.002). Multivariate analysis showed that C1QBP is an independent predictor of tumor size in progesterone-positive tumors. Furthermore, C1QBP was also significantly correlated with expression of PCNA, a known marker of proliferation. Inhibition of C1QBP expression was performed by transfecting C1QBP siRNA into T47D breast cancer cells, a progesterone receptor-positive breast cancer cell line. C1QBP gene expression was analyzed by real-time RT-PCR, and protein expression by Western blot. Cell proliferation assays were also performed by commercially available assays. Down-regulation of C1QBP expression significantly decreased cell proliferation and growth in T47D cells. Taken together, our findings suggest that the C1QBP protein could be a potential proliferative marker in breast cancer.     

Image-based radiodensity profilometry measures early remodeling at the bone-callus interface in sheep

Biomechanics and Modeling in Mechanobiology - Bone healing has been traditionally described as a four-phase process: inflammatory response, soft callus formation, hard callus development, and...     

Whole Exome Sequencing Identifies Mutations in Usher Syndrome Genes in Profoundly Deaf Tunisian Patients

Usher syndrome (USH) is an autosomal recessive disorder characterized by combined deafness-blindness. It accounts for about 50% of all hereditary deafness blindness cases. Three clinical subtypes (USH1, USH2, and USH3) are described, of which USH1 is the most severe form, characterized by congenital profound deafness, constant vestibular dysfunction, and a prepubertal onset of retinitis pigmentosa. We performed whole exome sequencing in four unrelated Tunisian patients affected by apparently isolated, congenital profound deafness, with reportedly normal ocular fundus examination. Four biallelic mutations were identified in two USH1 genes: a splice acceptor site mutation, c.2283-1G>T, and a novel missense mutation, c.5434G>A (p.Glu1812Lys), in MYO7A, and two previously unreported mutations in USH1G, i.e. a frameshift mutation, c.1195_1196delAG (p.Leu399Alafs*24), and a nonsense mutation, c.52A>T (p.Lys18*). Another ophthalmological examination including optical coherence tomography actually showed the presence of retinitis pigmentosa in all the patients. Our findings provide evidence that USH is under-diagnosed in Tunisian deaf patients. Yet, early diagnosis of USH is of utmost importance because these patients should undergo cochlear implant surgery in early childhood, in anticipation of the visual loss.     

Economic Evaluation of an Alternative Drug to Sulfadoxine-Pyrimethamine as Intermittent Preventive Treatment of Malaria in Pregnancy

Background

Intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) is recommended in HIV-negative women to avert malaria, while this relies on cotrimoxazole prophylaxis (CTXp) in HIV-positive women. Alternative antimalarials are required in areas where parasite resistance to antifolate drugs is high. The cost-effectiveness of IPTp with alternative drugs is needed to inform policy.

Methods

The cost-effectiveness of 2-dose IPTp-mefloquine (MQ) was compared with IPTp-SP in HIV-negative women (Benin, Gabon, Mozambique and Tanzania). In HIV-positive women the cost-effectiveness of 3-dose IPTp-MQ added to CTXp was compared with CTXp alone (Kenya, Mozambique and Tanzania). The outcomes used were maternal clinical malaria, anaemia at delivery and non-obstetric hospital admissions. The poor tolerability to MQ was included as the value of women’s loss of working days. Incremental cost-effectiveness ratios (ICERs) were calculated and threshold analysis undertaken.

Results

For HIV-negative women, the ICER for IPTp-MQ versus IPTp-SP was 136.30 US$ (2012 US$) (95%CI 131.41; 141.18) per disability-adjusted life-year (DALY) averted, or 237.78 US$ (95%CI 230.99; 244.57), depending on whether estimates from Gabon were included or not. For HIV-positive women, the ICER per DALY averted for IPTp-MQ added to CTXp, versus CTXp alone was 6.96 US$ (95%CI 4.22; 9.70). In HIV-negative women, moderate shifts of variables such as malaria incidence, drug cost, and IPTp efficacy increased the ICERs above the cost-effectiveness threshold. In HIV-positive women the intervention remained cost-effective for a substantial (up to 21 times) increase in cost per tablet.

Conclusions

Addition of IPTp with an effective antimalarial to CTXp was very cost-effective in HIV-positive women. IPTp with an efficacious antimalarial was more cost-effective than IPTp-SP in HIV-negative women. However, the poor tolerability of MQ does not favour its use as IPTp. Regardless of HIV status, prevention of malaria in pregnancy with a highly efficacious, well tolerated antimalarial would be cost-effective despite its high price.

Trials Registration

ClinicalTrials.gov NCT 00811421; Pan African Trials Registry PACTR2010020001429343 and PACTR2010020001813440     

COVID-19 in Africa: Catalyzing change for sustainable development

Salim Abdool Karim, Segenet Kelemu and Cheryl Baxter discuss COVID-19 impacts and adaptations in Africa.