Wischnewski Spots in a Case of Hyperosmolar Hyperglycemic State.

ABSTRACT: Wischnewski spots were first described as a common finding in gastric mucosa of decedents exposed to hypothermic environmental conditions. In recent literature, they were also reported in cases of diabetic ketoacidosis, pancreatitis, and fatal burns. Although Wischnewski spots are not specific to cases of hypothermia, we present a case that further supports this contention. We report a case of a middle-aged woman with type 2 diabetes who died of complications of hyperosmolar hyperglycemic state. Although there were no features of hypothermia, she presented with Wischnewski spots in the gastric mucosa. On histology, the gastric mucosa contained brown-black pigmentations with no neutrophilic infiltration. Biochemical analysis from vitreous humor and femoral blood showed marked elevation of glucose levels, low concentration of ketone bodies, pseudohyponatremia, and prerenal azotemia. The autopsy findings in this case discussion shed light to the possible genesis and pathophysiology of Wischnewski spots and highlight an additional differential diagnosis for these lesions.

Fatal methemoglobinemia: A case series highlighting a new trend in intentional sodium nitrite or sodium nitrate ingestion as a method of suicide.

Unintentional exposure to nitrite- or nitrate-containing toxic salts is a recognized cause of acquired methemoglobinemia (MetHb). This systemic alteration of the blood can be fatal if not recognized and treated promptly. The intentional ingestion of sodium nitrite (NaNO2) or sodium nitrate (NaNO3), causing MetHb, is an uncommon and recently identified method of suicide, with the first reported case in the literature occurring in New Zealand in 2010. In this case series we present 28 cases of sudden death of individuals with evidence of MetHb and/or toxic salt ingestion, occurring in the Province of Ontario, Canada, between the years 1980 and 2020, inclusive. Of the 28 deaths in our case series, 25 showed evidence of intentional ingestion of sodium nitrite or sodium nitrate salts. Our year-over-year data demonstrated this is an increasingly used method of suicide in our provincial population, with the majority of cases occurring in the final two years of our study. Postmortem detection of MetHb is typically established via screening techniques such as scene evidence suggesting fatal consumption of a toxic salt in addition to the characteristic grey-purple lividity observed upon the body. The diagnosis can be established via postmortem blood testing demonstrating elevated methemoglobin saturation. Additionally, we have confirmed that postmortem MRI in cases of MetHb demonstrates a T1-bright (hyperintense) signal of the blood; both within intracardiac blood on chest MRIs and postmortem blood samples in tubes.

CPR-associated right ventricular rupture in the setting of pulmonary embolism.

Cardiopulmonary resuscitation (CPR) is an inherently traumatic procedure. Successful resuscitations are often complicated by iatrogenic injuries to structures of the neck, thorax, or abdomen. Rib and sternal fractures are the most frequently induced injuries. However, rare and life-threatening trauma to vital organs such as the heart may also occur during CPR. We describe a novel case of CPR-associated right ventricular rupture in a woman with acute-on-chronic pulmonary embolism and no known pre-existing cardiac disease. We propose that chest compressions in the setting of elevated right ventricular pressure resulted in cardiac rupture, in this case.

Mycobacterium tuberculosis employs Cpn60.2 as an adhesin that binds CD43 on the macrophage surface.

CD43 is a large sialylated glycoprotein found on the surface of haematopoietic cells and has been previously shown to be necessary for efficient macrophage binding and immunological responsiveness to Mycobacterium tuberculosis. Using capsular material from M. tuberculosis and recombinant CD43-Fc, we have employed affinity chromatography to show that Cpn60.2 (Hsp65, GroEL), and to a lesser extent DnaK (Hsp70), bind to CD43. Competitive inhibition using recombinant protein and polyclonal F(ab')(2) antibody-mediated epitope masking studies were used to evaluate M. tuberculosis binding to CD43(+/+) versus CD43(-/-) macrophages. Results showed that Cpn60.2, but not DnaK, acts as a CD43-dependent mycobacterial adhesin for macrophage binding. Assessment of the specific binding between Cpn60.2 and CD43 showed it to be saturable, with a comparatively weak affinity in the low micromolar range. We have also shown that the ability of Cpn60.2 to competitively inhibit M. tuberculosis binding to macrophages is shared by the Escherichia coli homologue, GroEL, but not by the mouse and human Hsp60 homologues. These findings add to a growing field of research that implicates molecular chaperones as having extracellular functions, including bacterial adherence to host cells. Thus, CD43 may act as a Pattern Recognition Receptor (PRR) for bacterial homologues of the 60 kDa molecular chaperone.

Mycobacterium tuberculosis Cpn60.2 and DnaK are located on the bacterial surface, where Cpn60.2 facilitates efficient bacterial association with macrophages.

Mycobacterium tuberculosis, the causative agent of tuberculosis, initially contacts host cells with elements of its outer cell wall, or capsule. We have shown that capsular material from the surface of M. tuberculosis competitively inhibits the nonopsonic binding of whole M. tuberculosis bacilli to macrophages in a dose-dependent manner that is not acting through a global inhibition of macrophage binding. We have further demonstrated that isolated M. tuberculosis capsular proteins mediate a major part of this inhibition. Two-dimensional polyacrylamide gel electrophoresis analysis of the capsular proteins showed the presence of a wide variety of protein species, including proportionately high levels of the Cpn60.2 (Hsp65, GroEL2) and DnaK (Hsp70) molecular chaperones. Both of these proteins were subsequently detected on the bacterial surface. To determine whether these molecular chaperones play a role in bacterial binding, recombinant Cpn60.2 and DnaK were tested for their ability to inhibit the association of M. tuberculosis bacilli with macrophages. We found that recombinant Cpn60.2 can inhibit approximately 57% of bacterial association with macrophages, while DnaK was not inhibitory at comparable concentrations. Additionally, when polyclonal F(ab')(2) fragments of anti-Cpn60.2 and anti-DnaK were used to mask the surface presentation of these molecular chaperones, a binding reduction of approximately 34% was seen for anti-Cpn60.2 F(ab')(2), while anti-DnaK F(ab')(2) did not significantly reduce bacterial association with macrophages. Thus, our findings suggest that while M. tuberculosis displays both surface-associated Cpn60.2 and DnaK, only Cpn60.2 demonstrates adhesin functionality with regard to macrophage interaction.