Stimulating VAPB-PTPIP51 ER-mitochondria tethering corrects FTD/ALS mutant TDP43 linked Ca2+ and synaptic defects

Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are clinically linked major neurodegenerative diseases. Notably, TAR DNA-binding protein-43 (TDP43) accumulations are hallmark pathologies of FTD/ALS and mutations in the gene encoding TDP43 cause familial FTD/ALS. There are no cures for FTD/ALS. FTD/ALS display damage to a broad range of physiological functions, many of which are regulated by signaling between the endoplasmic reticulum (ER) and mitochondria. This signaling is mediated by the VAPB-PTPIP51 tethering proteins that serve to recruit regions of ER to the mitochondrial surface so as to facilitate inter-organelle communications. Several studies have now shown that disrupted ER-mitochondria signaling including breaking of the VAPB-PTPIP51 tethers are features of FTD/ALS and that for TDP43 and other familial genetic FTD/ALS insults, this involves activation of glycogen kinase-3β (GSK3β). Such findings have prompted suggestions that correcting damage to ER-mitochondria signaling and the VAPB-PTPIP51 interaction may be broadly therapeutic. Here we provide evidence to support this notion. We show that overexpression of VAPB or PTPIP51 to enhance ER-mitochondria signaling corrects mutant TDP43 induced damage to inositol 1,4,5-trisphosphate (IP3) receptor delivery of Ca2+ to mitochondria which is a primary function of the VAPB-PTPIP51 tethers, and to synaptic function. Moreover, we show that ursodeoxycholic acid (UDCA), an FDA approved drug linked to FTD/ALS and other neurodegenerative diseases therapy and whose precise therapeutic target is unclear, corrects TDP43 linked damage to the VAPB-PTPIP51 interaction. We also show that this effect involves inhibition of TDP43 mediated activation of GSK3β. Thus, correcting damage to the VAPB-PTPIP51 tethers may have therapeutic value for FTD/ALS and other age-related neurodegenerative diseases.

Evaluation of estimated glomerular function (eGFR) versus creatinine clearance (CrCl) to predict acute kidney injury when using zoledronate for the treatment of osteoporosis

Zoledronate could be contributing to the development of acute kidney injury in a small number of patients. Since estimated glomerular function (eGFR) is simpler to obtain and at least as good a predictor as creatinine clearance (CrCl), it should be used in everyday practice.

INTRODUCTION

Zoledronate is widely used for the treatment of osteoporosis. A potential side effect is acute kidney injury (AKI). Advice from the UK Medicines and Healthcare products Regulatory Agency (MHRA) in 2019 stated that CrCl and not estimated glomerular filtration rate (eGFR) should be used and that treatment should not be given if CrCl < 35 ml/min. The objective of this study was to compare our current method of assessing renal function (eGFR) with the method proposed by the MHRA (CrCl) for predicting AKI after zoledronate infusions.

METHODS

The evaluation was performed at the Metabolic Bone Centre in Sheffield Teaching Hospitals, UK. Data on all the patients who had zoledronate from 1/09/2015 to 1/10/2020 were included.

RESULTS

Data on 4405 patients were retrieved (total number of infusions 7660). Creatinine in the 14 days post-infusion was available for a total of 969 infusions and AKI was observed within 14 days following 45 infusions (4.6%). One patient died due to pneumonia. One patient needed continued haemodialysis. Severe AKI (threefold in creatinine and/or eGFR < 15 ml/min/173 m²) was observed within 1 year following 24 infusions. If the MHRA recommendations had been followed, 996 infusions with baseline CrCl < 35 ml/min would not have been given. Of these, follow-up data on serum creatinine within 14 days were available for 142 infusions, showing AKI in only four (2.8%). Logistic regression showed that both CrCl and eGFR were significant factors in predicting AKI within 14 days, but that the current recommended cut-off of CrCl 35 ml/min had poor sensitivity.

CONCLUSION

Since eGFR is at least as good a predictor of AKI as CrCl, and permits the treatment of more patients at high fracture risk, we recommend that eGFR is used to determine renal function for zoledronate treatment. We suggest that the infusion is given over 30 min in patients with eGFR < 50 ml/min/1.73 m².

Endoplasmic reticulum-mitochondria signaling in neurons and neurodegenerative diseases

Recent advances have revealed common pathological changes in neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis with related frontotemporal dementia (ALS/FTD). Many of these changes can be linked to alterations in endoplasmic reticulum (ER)-mitochondria signaling, including dysregulation of Ca2+ signaling, autophagy, lipid metabolism, ATP production, axonal transport, ER stress responses and synaptic dysfunction. ER-mitochondria signaling involves specialized regions of ER, called mitochondria-associated membranes (MAMs). Owing to their role in neurodegenerative processes, MAMs have gained attention as they appear to be associated with all the major neurodegenerative diseases. Furthermore, their specific role within neuronal maintenance is being revealed as mutant genes linked to major neurodegenerative diseases have been associated with damage to these specialized contacts. Several studies have now demonstrated that these specialized contacts regulate neuronal health and synaptic transmission, and that MAMs are damaged in patients with neurodegenerative diseases. This Review will focus on the role of MAMs and ER-mitochondria signaling within neurons and how damage of the ER-mitochondria axis leads to a disruption of vital processes causing eventual neurodegeneration.

Targeting ER-Mitochondria Signaling as a Therapeutic Target for Frontotemporal Dementia and Related Amyotrophic Lateral Sclerosis

Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are two major neurodegenerative diseases. FTD is the second most common cause of dementia and ALS is the most common form of motor neuron disease. These diseases are now known to be linked. There are no cures or effective treatments for FTD or ALS and so new targets for therapeutic intervention are required but this is hampered by the large number of physiological processes that are damaged in FTD/ALS. Many of these damaged functions are now known to be regulated by signaling between the endoplasmic reticulum (ER) and mitochondria. This signaling is mediated by "tethering" proteins that serve to recruit ER to mitochondria. One tether strongly associated with FTD/ALS involves an interaction between the ER protein VAPB and the mitochondrial protein PTPIP51. Recent studies have shown that ER-mitochondria signaling is damaged in FTD/ALS and that this involves breaking of the VAPB-PTPIP51 tethers. Correcting disrupted tethering may therefore correct many other downstream damaged features of FTD/ALS. Here, we review progress on this topic with particular emphasis on targeting of the VAPB-PTPIP51 tethers as a new drug target.

A patient with pleuritic chest pain and abnormal blood clotting tests

We present the case of a 58 year old man who developed pleuritic chest while an in-patient; investigations revealed pulmonary embolism, despite a significantly raised Activated Partial Thromboplastin Time (APTT), which was subsequently attributed to Antiphospholipid syndrome (APS). The diagnosis and initial management of APS in the acute setting is discussed.

Comparative study of outcome of the endoscopic sinus surgery and conventional surgery for nasal polyposis

This is a cross-sectional study done in Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka Medical College & Hospital (DMCH) & Bangladesh Institute of Research and Rehabilitation of Diabetic Endocrine and Metabolic Disorder (BIRDEM), Dhaka during the period of January 2009 to August 2010. This study included 60 cases of nasal polyposis, among them in 30 cases Functional Endoscopic Sinus Surgery (FESS) was done and in 30 cases conventional surgical procedure was done as treatment procedure. Here mean age of patient in FESS was 45.43 years and in conventional surgery was 45.13 years and male female ratio was 3.3:1. In this study postoperative complication of FESS were found in 07(23.33%) cases whereas in conventional surgery it were in 16 (53.33%) cases (p = <0.01, df = 1, Chi-squire = 7.65). In case of outcome, complete relief of symptoms occur in 22(73.33%) cases by FESS and 14(46.66%) cases by conventional procedure (p = <0.05 df = 2, Chi-squire = 9.29). In FESS 22(73.33%) cases and in conventional technique 14(46.67%) cases discharged within 24-48 hours (p = <0.05, df = 1, Chi-squire = 4.44). Recurrence after FESS was 6.67% cases and conventional surgery was 30% cases. The results of this series reveled that FESS had the combined advantages of precise removal of the disease with minimal complication.

A primary hypertrophic osteoarthropathy or pachydermoperiostosis

A young boy of 17 years presented with arthalgia and arthritis of multiple joints unresponsive to treatment, generalized clubbing and enlargement of distal part of the extremities for 5 years and hyperhidrosis for 3 years. On examination, thickening of the facial skin and seborrhoea were found associated with acne. The patient has a Marfanoid appearance with column like legs and spade like fingers. There was no evidence of cutis vertices gyrata. Mild anaemia was present and vital signs were within normal limits. Examination of the musculoskeletal system revealed pain and swelling of the knee, ankle, elbow, wrist and proximal & distal interphalangeal joints. The spine and gait were normal. Radiographs of the limbs revealed subperiosteal new bone formation. The patient was diagnosed as a case of the autosomal dominant disorder, Primary Hypertrophic Osteoarthropathy or Pachydermoperiostosis.

Bleeding after dental extractions in patients taking warfarin

OBJECTIVE

To assess the incidence of bleeding after dental extractions in subjects taking warfarin continuously before and after extractions whose International Normalised Ratio (INR) was below 4.0 at the time of extraction.

METHODS

This was a case series study of 150 patients without controls who required extraction of at least one tooth under local anaesthetic. All sockets were subsequently packed with absorbable oxycellulose and sutured.

RESULTS

A total of 58 women and 92 men were included (mean age 66 years); their ages were similar. The mean INR (S.D.) was 2.5 (0.56), although most patients had an INR less than 2.5 (n=101). Ten patients (7%) bled after extraction, enough to require a return to hospital. Five patients of 101 with an INR</=2.5, and 5 with an INR>2.5 out of 49 bled after extraction (p=0.29). Bleeding after extraction was not associated with operative antibiotics. All patients who bled were managed conservatively and none was admitted to hospital.

CONCLUSION

Patients taking warfarin whose INR is up to 4.0 and who have dental extractions in hospital do not have clinically significant bleeds post-operatively.

Inhibitor(S) of prostaglandin endoperoxide synthase and lipoxygenase activity in extracts of barley

Aqueous extract of barley was found to inhibit PG endoperoxide synthase and lipoxygenase enzymes responsible for arachidonic acid metabolism. Only 6% (v/v) of aqueous extract produced 50% inhibition of PG endoperoxide synthase while five times more extract was required to produce 50% inhibition of lipoxygenase. Boiling barley extract did not destroy the ability of the extract to inhibit the enzymes. Fractionation of barley with organic solvents, petroleum ether, chloroform, ethylacetate and acetone exhibited selectivity in its action in that foamy layer formed during petroleum ether and ethyl acetate extraction inhibited PG endoperoxide synthase completely whereas lipoxygenase activity was only partially inhibited. These results suggest the presence of inhibitor(s) of arachidonic acid metabolism in extracts of barley.

Rhabdomyosarcome para vertebral : cause rare de compression medullaire

Le rhabdomyosarcome est la tumeur maligne mésenchymateuse la plus fréquente chez l’enfant. Il se voit essentiellement au niveau des extrémités et la sphère ORL. La localisation paravertébrale avec compression médullaire est beaucoup plus rare. Les auteurs rapportent un cas de rhabdomyosarcome paravertébral avec extension endocanalaire et compression médullaire. Il s’agit d’une fille âgée de 6 ans admise pour un tableau de compression médullaire. L’examen clinique retrouve une patiente paraplégique avec niveau sensitif T8, des réflexes ostéo-tendineux abolis et une contracture des muscles paravertébraux. L’IRM médullaire montre un processus tissulaire à point de départ musculaire paravertébral droit, de signal hétérogène avec extension intra-canalaire et compression médullaire. La patiente a eu une laminectomie avec biopsie chirurgicale. L’étude histologique a posé le diagnostic d’un rhabdomyosarcome alvéolaire. La patiente a été traitée par chimiothérapie suivie d’une radiothérapie. L’IRM de contrôle a montré une régression totale du processus tumoral. Après un recul d’une année, la patiente a présenté une récidive locale avec métastases pulmonaires. Malgré cette localisation rare, le rhabdomyosarcome doit être évoqué devant un processus paravertébral avec extension épidurale et compression médullaire chez l’enfant.Mots clés : Rhabdomyosarcome, IRM, compression médullaire.