Clinicopathological Study of Mucormycosis in COVID-19 Patients: Experience From a Tertiary Care Center in South India

Background: The coronavirus disease 2019 (COVID-19) pandemic has taken the world to different dimensions. With the surge of the second wave in India, the number of cases with mucormycosis has increased. Mucormycosis is a potentially life-threatening, opportunistic, invasive, fungal infection that can occur in immunocompromised states. The aim of the study is to analyze the clinicopathological parameters of patients with mucormycosis in the surge of the second wave of COVID-19.

Materials and Methods: All cases of mucormycosis reported in the Department of Pathology in a tertiary care centre in South India from March 2021 to June 2021 were included in the study. The patient details were retrieved from the Medical Records section. The patient characteristics, location, associated comorbidities, management and treatment outcomes were analyzed and compared to similar studies reported worldwide.

Results: Of 58 cases, 38 (65%) were males and 20 (35%) were females. The ages ranged from 34 to 77 years. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detected in 46 patients in reverse transcription polymerase chain reaction (RT-PCR) with high-resolution computed tomography (HRCT) Chest changes noted in 54 patients. Associated comorbidities were noted in 52 patients, with uncontrolled diabetes mellitus (46 patients; 88%) being the most common. Location was commonly in nasal and paranasal sinuses (43%), followed by orbital (2%), cerebral (10%) and pulmonary (8%) areas. Among the paranasal sinuses, the maxillary sinus was commonly involved. Mixed fungal infections (Aspergillus sp. and Candida sp.) were noted in eight (14%) cases. Oxygen therapy was given in 85% of cases; 30% of cases needed ventilator support; corticosteroid therapy was initiated in 49 patients, tocilizumab in six patients as treatment for mucormycosis. Amphotericin B was administered in 59% of patients based on clinical findings alone. After histopathological confirmation, 90% of them received amphotericin. Functional endoscopic sinus surgery (FESS) was done in 96% of cases, among them 45% underwent extensive surgical debridement and 15% underwent orbital decompression. Orbital exenteration (2%) was the other modality of management.

Conclusion: Detailed analysis of clinicopathological features suggests the possibilities of immunosuppression (due to diabetes and use of corticosteroids in treatment of COVID-19) and COVID-19 (endothelial damage, cytokine storm) being the pathogenesis associated with the sudden surge of mucormycosis.

Hypobaric hypoxia induces dendritic plasticity in cortical and hippocampal pyramidal neurons in rat brain

Hypobaric hypoxia (HH), a predisposing environmental condition at high altitude (HA) encountered by many mountaineers jeopardizes their normal physiology like motor coordination and cognitive functions. Our previous studies revealed that the HH induces oxidative stress and neurodegeneration, which is associated with spatial memory impairment in rats. However, the dendritic changes after exposure to different duration of HH remain largely unknown. The aim of the present study was to investigate the duration-dependent dendritic changes in CA1, CA3 and entorhinal cortex (EC) of hippocampus and layer II of prefrontal cortex (PFC) with spatial memory functions in rats on exposure to different duration of HH. The rats were exposed to simulated HA of 6100 m for 3, 7, 14 and 21 days and the spatial reference memory was investigated using Morris water maze (MWM) and the morphological alteration of CA1, CA3, EC and layer II of PFC were investigated. There was a significant decrease in dendritic arborization and spine number along with increased number of damaged neurons, after 3, 7 and 14 days of HH but after 21 days of HH exposure the structural recovery was noted in all the regions. There was impairment of spatial memory after 3 and 7 days of exposure, but slight improvement of spatial memory was noted after 14 and 21 days of exposure. Our studies suggested that HH induces dendritic plasticity of PFC and hippocampal pyramidal neurons of rat brain, which might be associated with improvement of spatial memory function after 21 days of HH exposure.

N-acetyl cysteine supplementation prevents impairment of spatial working memory functions in rats following exposure to hypobaric hypoxia

Exposure to high altitude (HA), especially extreme altitude, is associated with impairment of cognitive functions including memory and increased oxidative stress. However, the underlying mechanisms involved are not well understood. It is hypothesized that HA induced oxidative stress may be one of the factors underlying hypoxia induced memory impairment. The aim of the present study was to investigate the effect of hypobaric hypoxia (HH) on spatial working and reference memory functions, oxidative stress markers in rats and effect of supplementation of N-acetyl cysteine (NAC). The rats were divided into four groups. Group I served as normoxic (n=6), Group II served as hypoxic (n=6), Group III as hypoxia group treated with NAC (n=6) and Group IV served as normoxic group treated with NAC (n=6). Group II & III were exposed to HH for 3 days equivalent to 6100 m and received oral NAC supplementation (750 mg/kg) daily. Rats from all the groups were trained in Morris Water Maze (MWM) task for 8 consecutive days. Spatial working and reference memory were tested immediately after the termination of HH and then the rats were sacrificed for estimation of oxidative stress markers in hippocampus. Rats displayed significant deficits in spatial working memory, and increased oxidative stress along with decrease in antioxidant status on hypoxic exposure. Supplementation with NAC in hypoxia-exposed group improved spatial memory performance, and decreased oxidative stress. These findings indicate that hypoxic exposure is associated with increased oxidative stress, which may have caused memory deficit in rats exposed to simulated HA.

Hypobaric hypoxia damages the hippocampal pyramidal neurons in the rat brain

Hypobaric hypoxia (HH), a predisposing environmental condition at high altitude (HA), encountered by many mountaineers, jeopardizes their normal physiology like motor coordination and cognitive functions. A large body of evidence shows that HH has deleterious effect on cognitive functions. Among them the hippocampal dependent memory deficit is well known. However, our current understanding of the mechanistic details of cognitive deficits at HA remains largely unclear and hence limits a solution for this problem. Therefore, the present study was designed to investigate the temporal component of the hippocampal pyramidal neuron damage in the rat brain subjected to chronic HH exposure. Three groups (sham HH, 3 days HH and 7 days HH) of rats were exposed to simulated HH equivalent to 6100 m in an animal decompression chamber for 3 or 7 days. Later, the hippocampal (CA1 and CA3) neurons were analysed for the cell morphology, neurodegeneration and DNA fragmentation. The CA1 and CA3 neurons showed HH induced neuronal pyknosis, cell shrinkage, and consequent inter-cellular vacuolization in the CA1 and CA3 areas. In addition, the total neuron (intact) numbers and mean surface area were decreased. The number of dead neurons increased significantly following exposure to HH for 3 or 7 days. The neurodegenerative (Fluoro jade B) and apoptotic (TUNEL) markers were more positive in CA1 and CA3 neurons. The magnitude of morphological changes, neurodegeneration and apoptosis was enhanced in 7 days HH group than 3 days HH group. Our studies indicate that CA3 neurons are more vulnerable to HH than CA1 neurons, and that may destabilize the neural circuits in the hippocampus and thus cause memory dysfunction.

Hypobaric hypoxia induces oxidative stress in rat brain

High altitude exposure results in decreased partial pressure of oxygen and an increased formation of reactive oxygen and nitrogen species (RONS), which causes oxidative damage to lipids, proteins and DNA. Exposure to high altitude appears to decrease the activity and effectiveness of antioxidant enzyme system. The antioxidant system is very less in brain tissue and is very much susceptible to hypoxic stress. The aim of the present study was to investigate the time dependent and region specific changes in cortex, hippocampus and striatum on oxidative stress markers on chronic exposure to hypobaric hypoxia. The rats were exposed to simulated high altitude equivalent to 6100 m in animal decompression chamber for 3 and 7 days. Results indicate an increase in oxidative stress as seen by increase in free radical production, nitric oxide level, lipid peroxidation and lactate dehydrogenase levels. The magnitude of increase in oxidative stress was more in 7 days exposure group as compared to 3 days exposure group. The antioxidant defence system such as reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) and reduced/oxidized glutathione (GSH/GSSG) levels were significantly decreased in all the three regions. The observation suggests that the hippocampus is more susceptible to hypoxia than the cortex and striatum. It may be concluded that hypoxia differentially affects the antioxidant status in the cortex, hippocampus and striatum.