Candida glabrata infection of a pancreatic pseudocyst in a COVID-19 patient: A case report and review of the literature

Introduction

Pancreatic pseudocysts remain a feared complication of acute or chronic pancreatitis and are often characterized by collections of fluids due to underlying damage to the pancreatic ducts, culminating in a walled-off region bereft of an epithelial layer but surrounded by granulation tissue. While fungal infections of pancreatic pseudocysts are rarely encountered, candida albicans remains the most frequently implicated organism.

Case presentation

A 55-year-old male presented with pain in the left-hypochondriac region, accompanied by non-bilious emesis and nausea. Interestingly, the patient also tested positive for a COVID-19 infection. Investigative workup divulged enhancing pancreatic walls with a radiologic impression consistent with a pancreatic pseudocyst. An ultrasound-guided external drainage was performed; the drainage was conducted unremarkably, with the resultant fluid collection revealing the presence of Candida Glabrata. The patient was commenced on antifungal therapy and continues to do well to date.

Discussion

Infectious ailments of pancreatic pseudocysts remain a widely known complication of acute pancreatitis. While it is rare, fungal infection is a crucial consideration for patients with pancreatic pseudocysts, especially in the context of a lack of an adequate response to antibiotics, deterioration, comorbidities, and immunocompromised states.

Conclusion

Rapid identification of the microbe responsible for pancreatic pseudocyst infection is vital for time-sensitive treatment and a more rapid recovery, curbing associated morbidity and mortality.

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Fungal infections of pancreatic pseudocysts remain a rare but well-characterized complication, culminating in significant morbidity and mortality.

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Telltale signs include unresponsiveness to antibiotics and worsening clinical symptoms.

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Rapid identification of the responsible microbe is vital for time-sensitive treatment and a more rapid recovery.

Meckel's diverticulum causing acute intestinal obstruction: A case report and comprehensive review of the literature

Introduction

Meckel's diverticulum is a congenital anomaly that is often detected incidentally. When it presents symptomatically, it causes painless gastrointestinal bleeding. Nevertheless, in rare instances, it can cause acute intestinal obstruction, often obscuring the true clinical picture.

Case presentation

A 31-year-old male presented to the emergency department with a 24-h history of unremitting nausea, biliary emesis, abdominal distension, and absolute constipation. After ruling out the most common etiologies of acute bowel obstruction, radiological imaging was obtained and was suggestive of meckel's diverticulum. Laparoscopic meckel's diverticulectomy was performed, with the subsequent histopathological analysis confirming ectopic gastric tissue.

Discussion

Meckel's diverticulum occurs consequent to incomplete obliteration of the vitelline or omphalomesenteric duct, which connects the developing intestines to the yolk sac. It is found in roughly 2% of the population, of which only about 4% may become symptomatic due to any number of complications. Specifically, small bowel obstruction (SBO) and diverticulitis secondary to ectopic gastric or pancreatic tissue are the most common presentations of symptomatic MD.

Conclusion

Although relatively rare in adults, MD should be considered in the list of differentials in patients with intussusception leading to SBO, especially on a background history unremarkable for the most common etiologies causing SBO including post-operative adhesions and hernias.

On the prevalence of flow instabilities from high-fidelity computational fluid dynamics of intracranial bifurcation aneurysms

High-fidelity computational fluid dynamics (HF-CFD) has revealed the potential for high-frequency flow instabilities (aka "turbulent-like" flow) in intracranial aneurysms, consistent with classic in vivo and in vitro reports of bruits and/or wall vibrations. However, HF-CFD has typically been performed on limited numbers of cases, often with unphysiological inflow conditions or focused on sidewall-type aneurysms where flow instabilities may be inherently less prevalent. Here we report HF-CFD of 50 bifurcation aneurysm cases from the open-source Aneurisk model repository. These were meshed using quadratic finite elements having an average effective spatial resolution of 0.065 mm, and solved under physiologically-pulsatile flow conditions using a well-validated, minimally-dissipative solver with 20,000 time-steps per cardiac cycle Flow instability was quantified using the recently introduced spectral power index (SPI), which quantifies, from 0 to 1, the power associated with velocity fluctuations above those of the driving inflow waveform. Of the 50 cases, nearly half showed regions within the sac having SPI up to 0.5, often with non-negligible power into the 100's of Hz, and roughly 1/3 had sac-averaged SPI > 0.1. High SPI did not significantly predict rupture status in this cohort. Proper orthogonal decomposition of cases with highest SPI_avg revealed time-varying energetics consistent with transient turbulence. Our reported prevalence of high-frequency flow instabilities in HF-CFD modelling of aneurysms suggests that care must be taken to avoid routinely overlooking them if we are to understand the highly dynamic mechanical forces to which some aneurysm walls may be exposed, and their prevalence in vivo.

Non-Newtonian versus numerical rheology: Practical impact of shear-thinning on the prediction of stable and unstable flows in intracranial aneurysms

Computational fluid dynamics (CFD) shows promise for informing treatment planning and rupture risk assessment for intracranial aneurysms. Much attention has been paid to the impact on predicted hemodynamics of various modelling assumptions and uncertainties, including the need for modelling the non-Newtonian, shear-thinning rheology of blood, with equivocal results. Our study clarifies this issue by contextualizing the impact of rheology model against the recently demonstrated impact of CFD solution strategy on the prediction of aneurysm flow instabilities. Three aneurysm cases were considered, spanning a range of stable to unstable flows. Simulations were performed using a high-resolution/accuracy solution strategy with Newtonian and modified-Cross rheology models and compared against results from a so-called normal-resolution strategy. Time-averaged and instantaneous wall shear stress (WSS) distributions, as well as frequency content of flow instabilities and dome-averaged WSS metrics, were minimally affected by the rheology model, whereas numerical solution strategy had a demonstrably more marked impact when the rheology model was fixed. We show that point-wise normalization of non-Newtonian by Newtonian WSS values tended to artificially amplify small differences in WSS of questionable physiological relevance in already-low WSS regions, which might help to explain the disparity of opinions in the aneurysm CFD literature regarding the impact of non-Newtonian rheology. Toward the goal of more patient-specific aneurysm CFD, we conclude that attention seems better spent on solution strategy and other likely "first-order" effects (eg, lumen segmentation and choice of flow rates), as opposed to "second-order" effects such as rheology.

Narrowing the Expertise Gap for Predicting Intracranial Aneurysm Hemodynamics: Impact of Solver Numerics versus Mesh and Time-Step Resolution

BACKGROUND AND PURPOSE

Recent high-resolution computational fluid dynamics studies have uncovered the presence of laminar flow instabilities and possible transitional or turbulent flow in some intracranial aneurysms. The purpose of this study was to elucidate requirements for computational fluid dynamics to detect these complex flows, and, in particular, to discriminate the impact of solver numerics versus mesh and time-step resolution.

MATERIALS AND METHODS

We focused on 3 MCA aneurysms, exemplifying highly unstable, mildly unstable, or stable flow phenotypes, respectively. For each, the number of mesh elements was varied by 320× and the number of time-steps by 25×. Computational fluid dynamics simulations were performed by using an optimized second-order, minimally dissipative solver, and a more typical first-order, stabilized solver.

RESULTS

With the optimized solver and settings, qualitative differences in flow and wall shear stress patterns were negligible for models down to ∼800,000 tetrahedra and ∼5000 time-steps per cardiac cycle and could be solved within clinically acceptable timeframes. At the same model resolutions, however, the stabilized solver had poorer accuracy and completely suppressed flow instabilities for the 2 unstable flow cases. These findings were verified by using the popular commercial computational fluid dynamics solver, Fluent.

CONCLUSIONS

Solver numerics must be considered at least as important as mesh and time-step resolution in determining the quality of aneurysm computational fluid dynamics simulations. Proper computational fluid dynamics verification studies, and not just superficial grid refinements, are therefore required to avoid overlooking potentially clinically and biologically relevant flow features.

Use of an additional hydrophobic binding site, the Z site, in the rational drug design of a new class of stronger trypanothione reductase inhibitor, quaternary alkylammonium phenothiazines

Improved rationally designed lead drug structures against African trypanosomiasis, Chagas disease, and leishmaniasis were obtained against trypanothione reductase from Trypanosoma cruzi. Substituted-benzyl [3-(2-chloro-4a, 10a-dihydrophenothiazin-10-yl)propyl]dimethylammonium salts, synthesized by Menschutkin quaternization of the tertiary alkylamine omega-nitrogen atom of chlorpromazine, were linear, competitive inhibitors of recombinant trypanothione reductase from T. cruzi, with either trypanothione disulfide or N-benzyloxycarbonyl-L-cysteinylglycyl 3-dimethylaminopropylamide disulfide as substrate. The permanent positive charge on the distal nitrogen atom of the tricyclic side chain contribution to binding was estimated as >/=5.6 kcal.mol(-1) by comparison with the analogue with the cationic nitrogen atom of the quaternary replaced by an ether oxygen atom. A further major contribution to improving K(i) values and inhibition strength was the hydrophobic natures and structures of the N-benzyl substituents. The strongest inhibitor, the [3-(2-chloro-4a,10a-dihydrophenothiazin-10-yl)propyl](3, 4-dichlorobenzyl)dimethylammonium derivative (K(i) 0.12 microM), was approximately 2 orders of magnitude more inhibitory than the parent chlorpromazine. Several of these quaternary phenothiazines completely inhibited T. brucei parasite growth in vitro at <1 microM. Antiparasite activity was not solely determined by inhibition strength against trypanothione reductase, there being a strong contribution from hydrophobicity (for example, benzhydryl-quaternized chlorpromazime had ED(50) < 1 microM). Although active against Leishmania donovani, none of the analogues showed major improvement in this activity relative to chlorpromazine or other nonquaternized phenothiazines. The p-tert-butylbenzyl-quaternized analogue very strongly inhibited (ED(50) < 1 microM) growth of the amastigote stage of T. cruzi.

Ecthyma gangrenosum in patients with acquired immunodeficiency syndrome

GOAL

To describe the reoccurrence of ecthyma gangrenosum (EG) in two patients with acquired immunodeficiency syndromes (AIDS).

OBJECTIVES

1. To describe the clinical characteristics of EG. 2. To discuss causative organism and risk factor for EG in patients with AIDS. 3. To identify rates of relapse/recurrence of EG in patients with AIDS.

Rational drug design using trypanothione reductase as a target for anti-trypanosomal and anti-leishmanial drug leads

The parasite enzyme trypanothione reductase has been used as a target for rational drug design against trypanosomiasis and leishmaniasis in a number of laboratories. In this article the biochemical basis for its selection as a target is reviewed. The relevant structural aspects of the target are then compared with the homologous structure found in the mammalian hosts to indicate the molecular basis by which selective toxicity is likely to be achieved. An overview of known classes of inhibitors is provided, preparatory to a detailed coverage of approaches that have been taken to obtaining strong, selective inhibitors and the steps taken in the process of the initial discovery of tricyclic structures by interactive molecular graphics ligand design are outlined. Recent quantitative docking approaches which have been applied to this system are also described. Finally, the biological data of the activity against the various parasitic forms in vitro and in vivo are summarised.