Allosteric Determinants in High Temperature Requirement A Enzymes Are Conserved and Regulate the Population of Active Conformations.

High temperature requirement A (HtrA) are allosterically regulated enzymes wherein effector binding to the PDZ domain triggers proteolytic activity. Yet, it remains unclear if the inter-residue network governing allostery is conserved across HtrA enzymes. Here, we investigated and identified the inter-residue interaction networks by molecular dynamics simulations on representative HtrA proteases, Escherichia coli DegS and Mycobacterium tuberculosis PepD, in effector-bound and free forms. This information was used to engineer mutations that could potentially perturb allostery and conformational sampling in a different homologue, M. tuberculosis HtrA. Mutations in HtrA perturbed allosteric regulation─a finding consistent with the hypothesis that the inter-residue interaction network is conserved across HtrA enzymes. Electron density from data collected on cryo-protected HtrA crystals revealed that mutations altered the topology of the active site. Ensemble models fitted into electron density calculated from room-temperature diffraction data showed that only a fraction of these models had a catalytically competent active site conformation alongside a functional oxyanion hole thus providing experimental evidence that these mutations influenced conformational sampling. Mutations at analogous positions in the catalytic domain of DegS perturbed the coupling between effector binding and proteolytic activity, thus confirming the role of these residues in the allosteric response. The finding that a perturbation in the conserved inter-residue network alters conformational sampling and the allosteric response suggests that an ensemble allosteric model best describes regulated proteolysis in HtrA enzymes.

Rhino-Orbito-Cerebral Mycosis and COVID-19: From Bad to Worse?

Background: There has been an increase an alarming rise in invasive mycoses during COVID-19 pandemic, especially during the second wave. Aims: Compare the incidence of invasive mycoses in the last three years and study the risk factors, manifestations and outcomes of mycoses in the COVID era. Methodology: Multicentric study was conducted across 21 centres in a state of western India over 12-months. The clinico-radiological, laboratory and microbiological features, treatment and outcomes of patients were studied. We also analysed yearly incidence of rhino-orbito-cerebral mycosis. Results: There was more than five-times rise in the incidence of invasive mycoses compared to previous two-years. Of the 122 patients analysed, mucor, aspergillus and dual infection were seen in 86.9%, 4.1%, and 7.4% respectively. Fifty-nine percent had simultaneous mycosis and COVID-19 while rest had sequential infection. Common presenting features were headache (91%), facial pain (78.7%), diplopia (66.4%) and vison loss (56.6%). Rhino-orbito-sinusitis was present in 96.7%, meningitis in 6.6%, intracranial mass lesions in 15.6% and strokes in 14.8%. A total of 91.8% patients were diabetic, while 90.2% were treated with steroids during COVID-19 treatment. Mortality was 34.4%. Conclusion: Invasive fungal infections having high mortality and morbidity have increased burden on already overburdened healthcare system. Past illnesses, COVID-19 itself and its treatment and environmental factors seem responsible for the rise of fungal infection. Awareness and preventive strategies are the need of hours and larger studies are needed for better understanding of this deadly disease.

Guillian--Barre' Syndrome in Patients with SARS-CoV-2: A Multicentric Study from Maharashtra, India.

BACKGROUND: Guillian--Barre' Syndrome (GBS) has been shown to be associated with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. The aim of our study was to study the clinical profile and outcomes of GBS in COVID-19 from the Western region of India, the State of Maharashtra. METHODS: This was a retrospective, multicenter observation study from different hospitals in Maharashtra beginning from March 2020 until November 2020. RESULTS: We report 42 patients with COVID-19 GBS. Mean age was 59 years (range, 24--85 years). 31/42 (73.8%) were men. GBS was the presenting symptom in 14/42 (33%), while six of them remained asymptomatic for COVID-19 despite positive SARS-CoV-2 on nasopharyngeal swab reverse transcriptase polymerase chain reaction. The median interval between COVID-19 and GBS was 14 days (SD + 11), with minimum of 1 and maximum 40 days. Clinical presentation was like that of typical GBS. Electrophysiological studies showed a predominant demyelinating pattern in 25/42 (59.5%). Inflammatory markers were elevated in 35/42 (83.3%) and 38/42 (90.5%) had an Abnormal high-resolution CT (HRCT) chest. 14/42 (33.3%) patients required a ventilator, with nine deaths. Intravenous immunoglobulin was the mainstay of treatment for GBS. Majority had a good outcome and were walking independently or with minimal support at discharge. In subgroup analysis, the postinfectious group had a better outcome than the parainfectious group. CONCLUSION: GBS in COVID-19 occurs as both parainfectious and postinfectious GBS. Parainfectious GBS needs more rigorous monitoring and may benefit from COVID-19 specific treatment. Routine screening for SARS-CoV-2 should be implemented in patients with GBS in view of the ongoing pandemic.

Behavioural and psychological symptoms in poststroke vascular cognitive impairment.

BACKGROUND: Behavioural and psychological symptoms of dementia (BPSD) cause significant patient and caregiver morbidity in vascular cognitive impairment (VCI). Objectives. To study and compare the occurrence and severity of BPSD between multi-infarct dementia (MID), subcortical ischaemic vascular disease (SIVD), and strategic infarct subtypes of poststroke VCI and to evaluate the relationship of these symptoms with the severity of cognitive impairment. METHODS: Sixty patients with poststroke VCI were classified into MID, SIVD, and strategic infarct subtypes. BPSD were studied by the neuropsychiatric inventory (NPI). The severity of cognitive impairment was evaluated by the clinical dementia rating scale (CDR). RESULTS: 95% of cases had at least one neuropsychiatric symptom, with depression being the commonest, irrespective of subtype or severity of VCI. Strategic infarct patients had the lowest frequency of all symptoms. SIVD showed a higher frequency and severity of apathy and higher total NPI scores, compared to MID. Apathy and appetite disturbances occurred more commonly with increasing CDR scores. The total NPI score correlated positively with the CDR score. CONCLUSION: Depression was the commonest neuropsychiatric symptom in VCI. The neuropsychiatric profiles of MID and SIVD were similar. The frequency and severity of apathy and the net burden of BPSD increased with increasing cognitive impairment.

The profile of behavioral and psychological symptoms in vascular cognitive impairment with and without dementia.

OBJECTIVE: The objective of this study was to compare the occurrence and severity of behavioral and psychological symptoms of dementia (BPSD) between vascular dementia (VaD) and vascular cognitive impairment-no dementia (VCI-ND). MATERIALS AND METHODS: Consecutive patients presenting with cognitive impairment at least 3 months after an ischemic stroke and with a Hachinski Ischemic Score ≥4 were included. VaD was diagnosed as per National Institute of Neurological Disorders and Stroke - Association Internationale pour la Recherche et l'Enseignement en Neurosciences criteria for probable VaD and VCI-ND on the lines of the Canadian study of health and aging. The severity of cognitive impairment and the behavioral/psychological symptoms were studied by means of the clinical dementia rating scale and the neuropsychiatric inventory (NPI) respectively. RESULTS: All patients with VaD and 89% of those with VCI-ND had at least one BPSD. The mean no. of symptoms per patient and the total NPI scores were higher in VaD than in VCI-ND. Apathy and night-time behavior disturbances were significantly more common and severe in VaD. CONCLUSIONS: BPSD are very common both in VCI-ND and in VaD. The profile of BPSD is similar in both groups, albeit more severe in VaD. The net burden of BPSD is higher in VaD as compared to VCI-ND.

A case of crossed aphasia with apraxia of speech.

Apraxia of speech (AOS) is a rare, but well-defined motor speech disorder. It is characterized by irregular articulatory errors, attempts of self-correction and persistent prosodic abnormalities. Similar to aphasia, AOS is also localized to the dominant cerebral hemisphere. We report a case of Crossed Aphasia with AOS in a 48-year-old right-handed man due to an ischemic infarct in right cerebral hemisphere.

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes unveiled by valproate.

Valproic acid (VPA) is widely used as an anti-epileptic drug. The primary mechanism of VPA toxicity is interference with mitochondrial beta-oxidation, and it can exacerbate an underlying mitochondrial cytopathy. We report a case of Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes unmasked by use of Sodium Valproate in a 12-year-old boy who presented with headache and seizures. There was precipitation of encephalopathy, myopathy, lactic acidosis, and hepatic damage within two days of valproate use, after withdrawing of which there was a remarkable clinical and biochemical recovery.

Clinical profile of psychogenic non-epileptic seizures in adults: A study of 63 cases.

AIMS: To evaluate clinical profile and short-term outcome of psychogenic non-epileptic seizures (PNES) in Indian adult population. SETTING AND DESIGN: A prospective observational study, conducted at tertiary teaching institute at New Delhi. MATERIALS AND METHODS: Sixty-three patients with confirmed PNES were enrolled. The diagnosis was based on witnessing the event during video-electroencephalography (Video-EEG) monitoring. A detailed clinical evaluation was done including evaluation for coexistent anxiety or depressive disorders. Patients were divided into two groups on the basis of excessive or paucity of movements during PNES attacks. Patients were followed-up to 12 months for their PNES frequency. STATISTICAL ANALYSIS: Means and standard deviations were calculated for continuous variables. Chi-square and Students t-test were used to compare categorical and continuous variables respectively. RESULTS: The mean age at onset of PNES was 25.44 years; with F:M ratio of 9.5:1. Coexistent epilepsy was present in 13 (20.63%) cases. Twenty-two patients (44%) with only PNES (n = 50) had received antiepileptic drugs. Out of 63 patients of PNES 24 (38.1%) had predominant motor phenomenon, whereas 39 (61.9%) had limp attacks. The common features observed were pre-ictal headache, ictal eye closure, jaw clenching, resistant behavior, ictal weeping, ictal vocalization, and unresponsiveness during episodes. Comorbid anxiety and depressive disorders was seen in 62.3% and 90.16% patients, respectively. Short-term (6-12 months) outcome of 45 patients was good (seizure freedom in 46.66% and >50% improvement in 24.44% cases). CONCLUSION: PNES is common, but frequently misdiagnosed and treated as epileptic seizures. A high index of suspicion is required for an early diagnosis. Proper disclosure of diagnosis and management of the psychiatric comorbidities can improve their outcome. LIMITATION: Limited sample size and change in seizures frequency as the only parameter for the assessment of the outcome are the two major limitations of our study.

Pathological laughter associated with paroxysmal kinesigenic dyskinesia: A rare presentation of acute disseminated encephalomyelitis.

A 13-year-old boy presented with recurrent episodes of sudden brief posturing of the right upper and lower limbs accompanied by transient inability to speak and a tendency to smile which would sometimes break into laughter. Awareness was retained during the attack, and there was no associated emotional abnormality. The events were precipitated by walking and occurred several times in a day. The laughter was pathological in nature, and the abnormal posturing was akin to 'paroxysmal kinesigenic dyskinesia' (PKD). 'Pathological laughter or crying' is defined as an involuntary, inappropriate, unmotivated laughter, crying or both, without any associated mood change. It can occur as a result of cerebral lesions like tumors, trauma, vascular insults, multiple sclerosis and/or degenerative disorders. It can also be a component of gelastic epilepsy which is characterized by stereotyped recurrences, presence of interictal and ictal epileptiform discharges and absence of external precipitants. In our patient, however, there was no ictal or interictal EEG correlate. Paroxysmal kinesigenic dyskinesia is characterized by intermittent, involuntary movements triggered by kinesigenic stimuli and is usually familial but can also be secondary to metabolic and structural brain disorders. Magnetic Resonance Imaging (MRI), in our case, revealed multiple T2 and FLAIR hyperintense, non-enhancing lesions in the periaqueductal gray matter, pontine and midbrain tegmentum, bilateral thalami and left lentiform nucleus suggesting a diagnosis of 'acute disseminated encephalomyelitis', in which this unique combination of pathological laughter and PKD has not been described so far. Magnetic Resonance Spectroscopy (MRS) confirmed a demyelinating pathology, and the patient responded well to steroids.