SARS-CoV-2 Dissemination Through Peripheral Nerves Explains Multiple Organ Injury

Coronavirus disease (CoVID-19), caused by recently identified severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2), is characterized by inconsistent clinical presentations. While many infected individuals remain asymptomatic or show mild respiratory symptoms, others develop severe pneumonia or even respiratory distress syndrome. SARS-CoV-2 is reported to be able to infect the lungs, the intestines, blood vessels, the bile ducts, the conjunctiva, macrophages, T lymphocytes, the heart, liver, kidneys, and brain. More than a third of cases displayed neurological involvement, and many severely ill patients developed multiple organ infection and injury. However, less than 1% of patients had a detectable level of SARS-CoV-2 in the blood, raising a question of how the virus spreads throughout the body. We propose that nerve terminals in the orofacial mucosa, eyes, and olfactory neuroepithelium act as entry points for the brain invasion, allowing SARS-CoV-2 to infect the brainstem. By exploiting the subcellular membrane compartments of infected cells, a feature common to all coronaviruses, SARS-CoV-2 is capable to disseminate from the brain to periphery via vesicular axonal transport and passive diffusion through axonal endoplasmic reticula, causing multiple organ injury independently of an underlying respiratory infection. The proposed model clarifies a wide range of clinically observed phenomena in CoVID-19 patients, such as neurological symptoms unassociated with lung pathology, protracted presence of the virus in samples obtained from recovered patients, exaggerated immune response, and multiple organ failure in severe cases with variable course and dynamics of the disease. We believe that this model can provide novel insights into CoVID-19 and its long-term sequelae, and establish a framework for further research.

Eudragit®-based microcapsules of probucol with a gut-bacterial processed secondary bile acid

AIM

Deoxycholic acid (DCA) has improved gliclazide oral absorption, while Eudragit^® (ED) polymers have improved formulation stability of antidiabetic drugs. The aim of the study is to test if DCA and ED encapsulation will optimize the release and stability of the potential antidiabetic drug probucol (PB).

MATERIALS & METHODS

The PB formulations were prepared using ED polymers and DCA, and formulations were analyzed for their rheological and biological properties.

RESULTS

Rheological properties and size distribution were similar among all groups. β-cell survival and biological activities were best with NM30D microcapsules. The inflammatory profile and oxidative stress effects of microcapsules remained similar among all groups.

CONCLUSION

ED NM30D and DCA incorporation can exert positive and stabilizing effects on PB oral microcapsules.

Challenges in nasal drug absorption: how far have we come?

The nasal route is commonly used for local delivery of drugs to treat inflammatory conditions. It is also an attractive route for systemic delivery of some drugs. Irrespective of intended use, administered drugs must permeate the epithelial or olfactory membrane to be effective. The enthusiasm for potential use of the nasal route for systemic drug delivery has not been met by comparable success. In this paper, the anatomical and physiological attributes of the nasal cavity and paranasal sinuses important for drug delivery and challenges limiting drug absorption are discussed. Efforts made so far in improving nasal drug absorption such as overcoming restrictive nasal geometry and paranasal sinuses accessibility, mucociliary clearance, absorption barriers, metabolism and drug physicochemical challenges are discussed. Highlights on future prospects of nasal drug delivery/absorption were discussed.

Prevalence of sinus membrane thickening and association with unhealthy teeth: a retrospective review of 831 consecutive patients with 1,662 cone-beam scans

PURPOSE

The purposes of this retrospective review of cone-beam computed tomographic (CBCT) scans were to 1) determine the prevalence of sinus membrane thickening in a consecutive series of patients; 2) identify the prevalence of healthy or unhealthy teeth associated with sinus membrane thickening; and 3) document changes of the sinus membrane after the removal of unhealthy teeth.

MATERIALS AND METHODS

Consecutive patients had CBCT scans examined and the sinuses were graded. Grade 1 represented membrane thickening of 0 to less than 2 mm; grade 2 represented thickening of 2 to 5 mm; grade 3 represented membrane or material thickening greater than 5 mm to the level of the ostium; and grade 4 represented soft tissue material superior to the ostium. Cross-sectional images were examined using software by the manufacturer of the CBCT scanner. Unhealthy teeth were identified. The examiner used a standardized approach in viewing the CBCT scans. Intraexaminer error was determined.

RESULTS

Eight hundred thirty-one patients had 1,662 sinuses evaluated, with thickening of at least 1 sinus membrane in 46.7% (388 patients) and 30.1% (469) of all sinuses evaluated. The prevalence of patients and sinuses with sinus membrane thickening according to the grading criteria was grade 2 for 36.8% of patients and 24.3% of sinuses, grade 3 for 6.0% of patients and 3.7% of sinuses, and grade 4 for 3.6% of patients and 2.2% of sinuses. Unilateral sinus disease was more common than bilateral disease. Of those sinuses with thickening, 80.6% were grade 2, 12.2% were grade 3, and 7.2% were grade 4. Of the 469 sinuses with membrane thickening, 210 were adjacent to unhealthy teeth, 233 were adjacent to healthy teeth, and 26 were in edentulous maxillas. Of the 210 unhealthy teeth, 30 had postextraction CBCT scans available for evaluation. Grade 2 sinus membrane thickening showed a 75% resolution to grade 1 after adjacent tooth removal. Grade 3 sinuses resolved in 25% to grade 1 and grade 2, with 50% remaining at grade 3. There were 2 grade 4 sinuses with follow-up scans, with 1 resolving to grade 2 and the other remaining at grade 4.

CONCLUSIONS

Sinus membrane thickening is present in 46.7% of patients presenting to an oral and maxillofacial surgical practice. The prevalence of sinus membrane thickening was almost equal in association with unhealthy and healthy teeth. The removal of unhealthy teeth decreased, but did not completely resolve sinus membrane thickening.

Oropharyngeal flora in patients admitted to the medical intensive care unit: clinical factors and acid suppressive therapy

Acid suppression therapy in critically ill patients significantly reduces the incidence of stress ulceration and gastrointestinal (GI) bleeding; however, recent studies suggest that proton pump inhibitors (PPIs) increase the risk of pneumonia. We wanted to test the hypothesis that acid suppressive therapy promotes alteration in the bacterial flora in the GI tract and leads to colonization of the upper airway tract with pathogenic species, potentially forming the biological basis for the observed increased incidence of pneumonia in these patients. This was a prospective observational study on patients (adults 18 years or older) admitted to the medical intensive care unit (MICU) at a tertiary care centre. Exclusion criteria included all patients with a diagnosis of pneumonia at admission, with infection in the upper airway, or with a history of significant dysphagia. Oropharyngeal cultures were obtained on day 1 and days 3 or 4 of admission. We collected data on demographics, clinical information, and severity of the underlying disease using APACHE II scores. There were 110 patients enrolled in the study. The mean age was 49±16 years, 50 were women, and the mean APACHE II score was 9.8 ± 6.5. Twenty per cent of the patients had used a PPI in the month preceding admission. The first oropharyngeal specimen was available in 110 cases; a second specimen at 72-96 h was available in 68 cases. Seventy-five per cent of the patients admitted to the MICU had abnormal flora. In multivariate logistic regression, diabetes mellitus and PPI use were associated with abnormal oral flora on admission. Chronic renal failure and a higher body mass index reduced the frequency of abnormal oral flora on admission. Most critically ill patients admitted to our MICU have abnormal oral flora. Patients with diabetes and a history of recent PPI use are more likely to have abnormal oral flora on admission.