Evidence for effect of l-serine, a novel therapy for GRIN2B-related neurodevelopmental disorder.

RATIONALE: To date, causal therapy is potentially available for GRIN2B-related neurodevelopmental disorder (NDD) due to loss-of-function (LoF) variants in GRIN2B, resulting in dysfunction of the GluN2B subunit-containing N-methyl-d-aspartate receptor (NMDAR). Recently, in vitro experiments showed that high doses of NMDAR co-agonist d-serine has the potential to boost the activity in GluN2B LoF variant-containing NMDARs. Initial reports of GRIN2B-NDD patients LoF variants, treated with l-serine using different regimens, showed varying effects on motor and cognitive performance, communication, behavior and EEG. Here, this novel treatment using a standardized protocol with an innovative developmental outcome measure is explored further in an open-label observational GRIN2B-NDD study. METHODS: Initially, in vitro studies were conducted in order to functionally stratify two de novo GRIN2B variants present in two female patients (18 months and 4 years old). Functional studies showed that both variants are LoF, and thus the patients were treated experimentally according to an approved protocol with oral l-serine (500 mg/kg/day in 4 doses) for a period of 12 months. Both patients showed a heterogeneous clinical phenotype, however overlapping symptoms were present: intellectual developmental disability (IDD), behavioral abnormalities and hypotonia. Outcome measures included laboratory tests, quality of life, sleep, irritability, stool, and performance skills, measured by, among others, the Perceive-Recall-Plan-Perform System of Task Analysis (PRPP-Assessment). RESULTS: Both patients tolerated l-serine without adverse effects. In one patient, improvement in psychomotor development and cognitive functioning was observed after 12 months (PRPP mastery score 10% at baseline, 78% at twelve months). In the most severe clinically affected patient no significant objective improvement in validated outcomes was observed. Caregivers of both patients reported subjective increase of alertness and improved communication skills. CONCLUSION: Our observational study confirms that l-serine supplementation is safe in patients with GRIN2B-NDD associated with LoF variants, and may accelerate psychomotor development and ameliorate cognitive performance in some but not all patients. The PRPP-Assessment, a promising instrument to evaluate everyday activities and enhance personalized and value-based care, was not performed in the severely affected patient, meaning that possible positive results may have been missed. To generate stronger evidence for effect of l-serine in GRIN2B-NDD, we will perform placebo-controlled n-of-1 trials.

A self-centring osteotomy of the tibial tubercle for patellar maltracking or instability: results with ten-years' follow-up.

An increased tibial tubercle-trochlear groove (TT-TG) distance is related to patellar maltracking and instability. Tibial tubercle transfer is a common treatment option for these patients with good short-term results, although the results can deteriorate over time owing to the progression of osteoarthritis. We present a ten-year follow-up study of a self-centring tibial tubercle osteotomy in 60 knees, 30 with maltracking and 30 with patellar instability. Inclusion criteria were a TT-TG ≥ 15 mm and symptoms for > one year. One patient (one knee) was lost to follow-up and one required total knee arthroplasty because of progressive osteoarthritis. Further patellar dislocations occurred in three knees, all in the instability group, one of which required further surgery. The mean visual analogue scores for pain, and Lysholm and Kujala scores improved significantly and were maintained at the final follow-up (repeated measures, p = 0.000, intergroup differences p = 0.449). Signs of maltracking were found in only a minority of patients, with no difference between groups (p > 0.05). An increase in patellofemoral osteoarthritis was seen in 16 knees (31%) with a maximum of grade 2 on the Kellgren-Lawrence scale. The mean increase in grades was 0.31 (0 to 2) and 0.41 (0 to 2) in the maltracking and instability groups respectively (p = 0.2285) This self-centring tibial tubercle osteotomy provides good results at ten years' follow-up without inducing progressive osteoarthritis.

Autophagy activity is up-regulated in adipose tissue of obese individuals and modulates proinflammatory cytokine expression.

Autophagy, an evolutionary conserved process aimed at recycling damaged organelles and protein aggregates in the cell, also modulates proinflammatory cytokine production in peripheral blood mononuclear cells. Because adipose tissue inflammation accompanied by elevated levels of proinflammatory cytokines is characteristic for the development of obesity, we hypothesized that modulation of autophagy alters adipose tissue inflammatory gene expression and secretion. We tested our hypothesis using ex vivo and in vivo studies of human and mouse adipose tissue. Levels of the autophagy marker LC3 were elevated in sc adipose tissue of obese vs. lean human subjects and positively correlated to both systemic insulin resistance and morphological characteristics of adipose tissue inflammation. Similarly, autophagic activity levels were increased in adipose tissue of obese and insulin resistant animals as compared with lean mice. Inhibition of autophagy by 3-methylalanine in human and mouse adipose tissue explants led to a significant increase in IL-1ß, IL-6, and IL-8 mRNA expression and protein secretion. Noticeably, the enhancement in IL-1ß, IL-6, and keratinocyte-derived chemoattractant (KC) by inhibition of autophagy was more robust in the presence of obesity. Similar results were obtained by blocking autophagy using small interfering RNA targeted to ATG7 in human Simpson-Golabi-Behmel syndrome adipocytes. Our results demonstrate that autophagy activity is up-regulated in the adipose tissue of obese individuals and inhibition of autophagy enhances proinflammatory gene expression both in adipocytes and adipose tissue explants. Autophagy may function to dampen inflammatory gene expression and thereby limit excessive inflammation in adipose tissue during obesity.

Response of biting midges (Diptera: Ceratopogonidae) to carbon dioxide, octenol, and light in southeastern Queensland, Australia.

The effect of 1-octen-3-ol (octenol) on catches of estuarine biting midges in encephalitis vector surveillance (EVS) traps was examined in southeastern Queensland. Octenol by itself was not attractive but appeared to act as a synergist with CO2 to increase catches of most species. For four of six species tested, a medium (about 6 mg/h) release rate of octenol captured the most individuals. Addition of light also increased the catch size of most species. Octenol in combination with CO2 could be used to enhance biting midge catch size, improving the sensitivity of surveillance for midges and the pathogens they vector.

Differential responses of Aedes and Culex mosquitoes to octenol or light in combination with carbon dioxide in Queensland, Australia.

Field studies were conducted with EVS (encephalitis vector surveillance) traps in south-eastern Queensland, Australia, to determine the relative response rates of mosquitoes to three levels (0.1, 4.5 and 30 mg/h) of 1-octen-3-ol (octenol) in combination with a standard bait of 2200 g carbon dioxide (CO2), compared with CO2 alone or CO2 with light from a 6V incandescent bulb. Compared to CO2 alone, Aedes vigilax collections increased significantly when CO2 was supplemented by all three octenol emission levels, but not by the addition of light. Furthermore, the 4.5 and 30 mg/h release rate of octenol gave a significant increase in numbers of Ae.vigilax relative to that from CO2+light. In contrast, collections of Culex annulirostris and Culex sitiens were not enhanced significantly by either the addition of light or octenol at all three levels. Fewer Cx sitiens were collected with octenol released at 4.5 mg/h in comparison to CO2 alone. These differential sampling rates should be taken into account when using EVS traps.

Response of mosquitoes to carbon dioxide and 1-octen-3-ol in southeast Queensland, Australia.

Encephalitis vector surveillance (EVS) traps were used to study the attractant effect of CO2 and 1-octen-3-ol (octenol) on mosquitoes at 2 different locations in southeast Queensland. Octenol alone was only slightly attractive for Aedes vigilax. There was a significant increase in the numbers of Ae. vigilax and Aedes funereus caught when octenol was added to CO2, although catches of Culex annulirostris and Culex sitiens did not change significantly. The size and age compositions of Ae. vigilax attracted by CO2 and by octenol were comparable. These data suggest that octenol should be considered as a supplement to CO2-baited EVS traps for mosquito-based arbovirus surveillance in southeast Queensland.