Molecular epidemiology of resistance to antimalarial drugs in the Greater Mekong subregion: an observational study

BACKGROUND

The Greater Mekong subregion is a recurrent source of antimalarial drug resistance in Plasmodium falciparum malaria. This study aimed to characterise the extent and spread of resistance across this entire region between 2007 and 2018.

METHODS

P falciparum isolates from Myanmar, Thailand, Laos, and Cambodia were obtained from clinical trials and epidemiological studies done between Jan 1, 2007, and Dec 31, 2018, and were genotyped for molecular markers (pfkelch, pfcrt, pfplasmepsin2, and pfmdr1) of antimalarial drug resistance. Genetic relatedness was assessed using microsatellite and single nucleotide polymorphism typing of flanking sequences around target genes.

FINDINGS

10 632 isolates were genotyped. A single long pfkelch Cys580Tyr haplotype (from -50 kb to +31·5 kb) conferring artemisinin resistance (PfPailin) now dominates across the eastern Greater Mekong subregion. Piperaquine resistance associated with pfplasmepsin2 gene amplification and mutations in pfcrt downstream of the Lys76Thr chloroquine resistance locus has also developed. On the Thailand-Myanmar border a different pfkelch Cys580Tyr lineage rose to high frequencies before it was eliminated. Elsewhere in Myanmar the Cys580Tyr allele remains widespread at low allele frequencies. Meanwhile a single artemisinin-resistant pfkelch Phe446Ile haplotype has spread across Myanmar. Despite intense use of dihydroartemisinin-piperaquine in Kayin state, eastern Myanmar, both in treatment and mass drug administrations, no selection of piperaquine resistance markers was observed. pfmdr1 amplification, a marker of resistance to mefloquine, remains at low prevalence across the entire region.

INTERPRETATION

Artemisinin resistance in P falciparum is now prevalent across the Greater Mekong subregion. In the eastern Greater Mekong subregion a multidrug resistant P falciparum lineage (PfPailin) dominates. In Myanmar a long pfkelch Phe446Ile haplotype has spread widely but, by contrast with the eastern Greater Mekong subregion, there is no indication of artemisinin combination therapy (ACT) partner drug resistance from genotyping known markers, and no evidence of spread of ACT resistant P falciparum from the east to the west. There is still a window of opportunity to prevent global spread of ACT resistance.

FUNDING

Thailand Science Research and Innovation, Initiative 5%, Expertise France, Wellcome Trust.

Rotating dome trochleoplasty: An experimental technique for correction of patellar luxation using a feline model

The purpose of this study was to compare a trochlear block recession to a rotating dome trochleoplasty, a novel technique for the correction of patellar luxation in small animals. Twenty-eight limbs were used from 14 feline cadavers. With the stifles in flexion and extension, computed tomography was utilized to compare width and depth of the trochlea, medial trochlear ridge height, trochlear articular surface area preserved, patellar contact articular surface area, patellar area covered by the trochlear ridges and patellar tilt angle. The results of this study demonstrated that a rotating dome trochleoplasty is superior to a trochlear block recession with regard to medial trochlear height, trochlear width, trochlear depth and trochlear surface area preservation. The results of this study support further biomechanical evaluation of this technique which eventually may lead to clinical trials.

Prevalence of parent-reported immediate hypersensitivity food allergy in Chilean school-aged children

BACKGROUND

Food allergies (FAs) affect 2-4% of school-aged children in developed countries and strongly impact their quality of life. The prevalence of FA in Chile remains unknown.

METHODS

Cross-sectional survey study of 488 parents of school-aged children from Santiago who were asked to complete a FA screening questionnaire. Parents who reported symptoms suggestive of FA were contacted to answer a second in-depth questionnaire to determine immediate hypersensitivity FA prevalence and clinical characteristics of school-aged Chilean children.

RESULTS

A total of 455 parents answered the screening questionnaire: 13% reported recurrent symptoms to a particular food and 6% reported FA. Forty-three screening questionnaires (9%) were found to be suggestive of FA. Parents of 40 children answered the second questionnaire; 25 were considered by authors to have FA. FA rate was 5.5% (95% CI: 3.6-7.9). Foods reported to frequently cause FA included walnut, peanut, egg, chocolate, avocado, and banana. Children with FA had more asthma (20% vs. 7%, P<0.02) and atopic dermatitis (32% vs. 13%, P<0.01) by report. The parents of children with FA did not report anaphylaxis, but 48% had history compatible with anaphylaxis. Of 13 children who sought medical attention, 70% were diagnosed with FA; none were advised to acquire an epinephrine autoinjector.

CONCLUSION

Up to 5.5% of school-aged Chilean children may suffer from FA, most frequently to walnut and peanut. It is critical to raise awareness in Chile regarding FA and recognition of anaphylaxis, and promote epinephrine autoinjectors in affected children.

Reflections on mental capacity assessments in general hospitals

Research suggests that a significant proportion of inpatients in general medical wards may lack capacity to make treatment decisions, a situation that often goes unrecognised by clinicians. We would like to briefly discuss two cases from a non-psychiatric setting, where a mental disorder served to inhibit the individual's ability to weigh-up associated risks when deciding to refuse potentially life-sustaining healthcare interventions. In both cases the history of mental disorder was well established yet, for markedly different reasons, the respective presentation was such that the influence of the disorder on decision-making was not evident to the treating teams.

The effect of Zhangfei on the unfolded protein response and growth of cells derived from canine and human osteosarcomas

The objective of this study was to determine whether the protein Zhangfei could suppress the unfolded protein response (UPR) and growth of osteosarcoma cells. Dog (D-17) and a human (Saos-2) osteosarcoma cells were infected with adenovirus vectors expressing either Zhangfei or the control protein beta- galactosidase. We monitored cell growth as well as levels of UPR gene transcripts and proteins. We found that Zhangfei suppressed the growth of both D-17 and Saos-2 cells. Zhangfei-expressing D-17 cells displayed large vacuoles containing culture medium and expressed phosphatidylserine on their external surface suggesting that Zhangfei induced macropinocytosis and apoptosis in these cells. While Zhangfei inhibited the growth of both D-17 and Saos-2 cells, it inhibited thapsigargin-induced UPR, as detected by a decrease in transcripts for UPR genes, and HERP and GRP78 proteins, only in D-17 cells, suggesting that the ability of Zhangfei to suppress the UPR and tumour cells growth may not be linked.

132 A NEW APPROACH TO ASSESS OVARIAN STRUCTURES IN LIVE RABBITS: SURGICAL TRANSLOCATION AND ULTRASOUND BIOMICROSCOPY

For the purpose of determining factors associated with ovulation induction in rabbits, there is a need to examine the ovaries in a serial fashion. To this end, a study was designed to develop an approach that would permit serial evaluation of ovarian structures in vivo using ultrasound biomicroscopy (UBM) while preserving ovarian function in rabbits. The use of UBM has enabled characterisation of ovarian dynamics in live mice and has recently been validated for assessing structures in excised rabbit ovaries (Cervantes et al. 2011 Reprod. Fertil. Dev. 23, 183–184). However, acoustic impedance of the body wall prevented acquisition of high-quality ovarian images in vivo by transabdominal UBM in rabbits. Female New Zealand White rabbits (5 months old; n = 12) underwent surgical ovarian translocation. Each ovary was exteriorized through a lateral flank incision on the respective sides, without compromising vascular supply. The mesovarium at each pole of the ovary was transfixed to the muscle layers of the abdominal wall to keep the ovary in a subcutaneous position. Finally, the subcutaneous and skin layers were closed. No postoperative complications were observed. The surgical site was allowed to heal for 2 weeks and the skin sutures were removed before UBM was attempted. The rabbits were wrapped in a towel for restraint without sedation. Acoustic gel was applied to the shaved skin over the translocated ovary and ovarian structures were imaged transcutaneously by UBM using a 25-MHz transducer on 3 consecutive days. Both ovaries were clearly distinguished in all 12 rabbits during each examination. Antral follicles ranging from 0.6 to 3.1 mm were detected and the number of follicles ≥0.6 mm per pair of ovaries ranged from 7 to 18. Data were analysed by one-way ANOVA. The number and diameter of follicles ≥0.6 mm per rabbit did not differ among the 3 examinations (mean ± s.e.m.; 11.0 ± 0.82, 11.8 ± 0.85 and 12.3 ± 0.75 follicles and 1.3 ± 0.07, 1.3 ± 0.07 and 1.4 ± 0.07 mm, respectively). However, follicles ≥2 mm in diameter were detected in 3 out of 12 rabbits on the first and second days and in 5 out of 12 rabbits on the third day. One or more corpora lutea were detected in the same 2 rabbits (2/12) during each of the 3 examination days. Two months after surgery, ovarian structures were clearly discernible by UBM in 11 of 24 translocated ovaries. Image deterioration was attributed to the attenuation of sound waves associated with increased skin thickness and growth of subcutaneous fat and connective tissue around the ovary, assessed at necropsy. In summary, translocated ovaries continued to function in their new location and transcutaneous UBM permitted serial visualisation of ovarian structures in live rabbits. Therefore, this new approach provides a nonterminal alternative for repetitive examination of rabbit ovaries and is particularly appropriate for experiments involving factors associated with ovulation induction in rabbits. This research was supported by the Natural Sciences and Engineering Research Council of Canada.

Open resection for subvalvular aortic stenosis in dogs

OBJECTIVE

To describe the surgical technique for open resection of congenital subvalvular aortic stenosis in dogs and to determine outcome of dogs undergoing the procedure.

DESIGN

Uncontrolled clinical trial.

ANIMALS

17 dogs with congenital discrete subvalvular aortic stenosis.

PROCEDURE

Dogs were placed on cardiopulmonary bypass by catheterizing the femoral artery and both vena cavae. The aorta was cross clamped, and cold cardioplegia solution was administered. The aortic root then was opened with a curvilinear incision. A subvalvular discrete fibrous ring was resected in all dogs. Septal myectomy was performed simultaneously on 11 dogs.

RESULTS

15 of 17 dogs survived the operation and were discharged from the hospital. Mean +/- SD maximal instantaneous aortic systolic pressure gradient measured by means of Doppler echocardiography was significantly reduced from 119 +/- 42 mm of Hg before surgery to 41 +/- 10 mm of Hg 12 months after surgery. Despite substantial reduction in the systolic pressure gradient, 4 of 15 dogs died suddenly between 7 days and 30 months after surgery. Three of the 4 dogs that died suddenly had pressure gradients > or = 180 mm of Hg and ventricular tachycardia before surgery. Eleven dogs were still alive between 1 and 48 months after surgery.

CLINICAL IMPLICATIONS

The procedure resulted in substantial reductions in systolic pressure gradients in dogs with severe congenital subvalvular aortic stenosis. However, some dogs with severe aortic stenosis died suddenly after surgery. Thus, this surgery should not be considered curative. Proof of a survival benefit in dogs undergoing this surgery will have to await longer term follow-up.

Bromide toxicosis secondary to renal insufficiency in an epileptic dog

Bromide toxicosis was diagnosed in an 8-year-old Labrador Retriever that had been treated for epilepsy with potassium bromide, at a dosage of 29 mg/kg of body weight/d. Clinical signs included hind limb weakness, ataxia, and disorientation. Renal insufficiency, diagnosed by determination of endogenous creatinine clearance, was believed to be responsible for the development of bromide toxicosis in this dog. Diuresis with physiologic saline solution and discontinuation of bromide and phenobarbital treatment resulted in rapid resolution of abnormal neurologic signs; however, serum bromide concentrations decreased dramatically during diuresis and seizures recurred. Although saline diuresis has been recommended for the treatment of bromide intoxication in human beings, more conservative measures, such as discontinuation of bromide and short-term fluid administration, may be more appropriate for epileptic dogs.

Closed transventricular dilation of discrete subvalvular aortic stenosis in dogs

Discrete subvalvular aortic stenosis with peak systolic pressure gradients of more than 60 mm Hg was treated by closed transventricular dilation in six young dogs. Peak systolic pressure gradients were measured by direct catheterization before surgery, immediately after dilation, and 3 months after surgery. Maximum instantaneous pressure gradients were measured by continuous wave Doppler echocardiography before surgery and 6 weeks to 9 months after surgery. All dogs survived the procedure, and two dogs were clinically normal after 9 and 14 months. Two dogs died at week 6 and month 7. One dog was receiving medication for pulmonary edema 15 months after surgery. One dog underwent open resection of the subvalvular ring at month 3, and was clinically normal 6 months after the second procedure. Complications included intraoperative ventricular fibrillation in one dog, and mild postoperative aortic insufficiency in one dog. Closed transventricular dilation resulted in an immediate 83% decrease in the peak systolic pressure gradient from a preoperative mean of 97 +/- 22 mm Hg to a mean of 14 +/- 15 mm Hg. However, systolic pressure gradients measured by direct catheterization at month 3 (77 +/- 26 mm Hg), and by Doppler echocardiography at week 6 to month 9 (85 +/- 32 mm Hg) were not significantly different from preoperative values, which suggested recurrence of the aortic stenosis. Closed transventricular dilation should not be considered a definitive treatment for discrete subvalvular aortic stenosis in dogs, but may be useful in young dogs with critical aortic stenosis as a bridge to more definitive surgery.