Case report: Diarrhea-associated hemolytic uremic syndrome in the Era of COVID-19

Over the past two years, a growing number of SARS-CoV-2 infection-associated clinical pediatric phenotypes have been identified, including a hemolytic uremic syndrome (HUS) form of thrombotic microangiopathy. Oregon's high prevalence of Shiga toxin-producing Escherichia coli (STEC) infections gives it a unique perspective to discuss the impact of COVID-19 and HUS. We seek to highlight SARS-CoV-2 as a potential new infectious etiology of severe diarrhea-associated HUS, based on two cases from Portland, Oregon, occurring in non-COVID-19 immunized children. The first case is a previously healthy ten-year-old who presented with SARS-CoV-2 infection and bloody diarrhea after an appendectomy, followed by full-blown oligo-anuric HUS. Second is a previously healthy six-year-old who presented with short-lived bloody diarrhea, rapidly evolving to HUS, and who tested positive for COVID-19 via polymerase chain reaction and STEC toxins one and two. These two cases highlight two main points. First, SARS-CoV-2 must be included in the differential diagnosis of diarrhea-associated HUS, either as the sole agent or concurrent with a STEC infection. Second, when managing STEC gastroenteritis the recommendation has been to maintain excellent hydration as a strategy to prevent the progression to oligo-anuric acute kidney injury and HUS. This strategy may need to be re-evaluated in a patient with SARS-CoV-2 infection or co-infection.

A novel algorithm for automatic diagnosis of sleep apnea from airflow and oximetry signals

OBJECTIVE

Sleep apnea significantly decreases the quality of life. The apnea hypopnea index (AHI) is the main indicator for sleep apnea diagnosis. This study explored a novel automatic algorithm to diagnose sleep apnea from nasal airflow (AF) and pulse oximetry (SpO₂) signals.

APPROACH

Of the 988 polysomnography (PSG) records from the sleep heart health study (SHHS), 45 were randomly selected for the development of an algorithm and the remainder for validation (n = 943). The algorithm detects apnea events by a digitization process, following the determination of the peak excursion (peak-to-trough amplitude) from AF envelope. Hypopnea events were determined from the AF envelope and oxygen desaturation with correction to time lag in SpO₂. Total sleep time (TST) was estimated from an optimized percentage of artefact-free total recording time. AHI was estimated from the number of detected events divided by the estimated TST. The estimated AHI was compared to the scored SHHS data for performance evaluation.

MAIN RESULTS

The validation showed good agreement between the estimated and scored AHI (intraclass correlation coefficient of 0.95 and mean ±95% limits of agreement of -1.6 ±12.5 events h^-1). The diagnostic accuracies were found: 90.7%, 91%, and 96.7% for AHI cut-off ≥5, ≥15, and ≥30 respectively.

SIGNIFICANCE

The new algorithm is accurate over other existing methods for the automatic diagnosis of sleep apnea. It is applicable to any portable sleep screeners especially for the home diagnosis of sleep apnea.

Teaching Pediatric Peritoneal Dialysis Globally through Virtual Simulation

BACKGROUND AND OBJECTIVES

Despite the increasing prevalence of childhood kidney disease worldwide, there is a shortage of clinicians trained to provide peritoneal dialysis (PD). E-learning technologies may provide a solution to improve knowledge in PD. We describe the development of a virtual PD simulator and report the first 22 months of online usage.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The PD simulator was developed and released on OPENPediatrics in January of 2016. A prospective study of international, multidisciplinary healthcare providers was conducted from January of 2016 through October of 2017. User action data were analyzed with descriptive statistics and linear regression. Paired t tests compared user pre- and post-test scores. User satisfaction was assessed by survey.

RESULTS

The simulator was accessed by 1066 users in 70 countries. Users spent a median of 35 minutes (interquartile range [IQR] 14-84) in the simulator. Users who completed the structured learning curriculum (n=300) spent a median of 85 minutes (IQR 46-95), and those who completed the entire simulator (n=63) spent a median of 122 minutes (IQR 69-195). Users who completed the simulator were more likely to scroll through text and access the simulator in multiple sessions. The 300 users that completed testing showed statistically significant increases in the post- versus pretest scores, with a mean increase of 36.4 of 100 points, SD 19.9 (95% confidence interval, 34.1 to 38.6, P<0.001). Eighty-seven percent (20 of 23) of survey respondents felt the simulator was relevant to their clinical practice, and 78% (18 of 23) would recommend it to others.

CONCLUSIONS

This is the first reported virtual PD simulator. Increased test scores were observed between pre- and post-tests by clinicians who completed testing, across disciplines, training levels, and resource settings.

Acute kidney injury associated with smoking synthetic cannabinoid

CONTEXT AND OBJECTIVES

Synthetic cannabinoids are illegal drugs of abuse known to cause adverse neurologic and sympathomimetic effects. They are an emerging health risk: 11% of high school seniors reported smoking them during the previous 12 months. We describe the epidemiology of a toxicologic syndrome of acute kidney injury associated with synthetic cannabinoids, review the toxicologic and public health investigation of the cluster, and describe clinical implications of the cluster investigation.

MATERIALS AND METHODS

Case series of nine patients affected by the toxicologic syndrome in Oregon and southwestern Washington during May-October 2012. Cases were defined as acute kidney injury (creatinine > 1.3 mg/dL) among persons aged 13-40 years without known renal disease who reported smoking synthetic cannabinoids. Toxicology laboratories used liquid chromatography and time-of-flight mass spectrometry to test clinical and product specimens for synthetic cannabinoids, their metabolites, and known nephrotoxins. Public health alerts informed clinicians, law enforcement, and the community about the cluster and the need to be alert for toxidromes associated with emerging drugs of abuse.

RESULTS

Patients were males aged 15-27 years (median, 18 years), with intense nausea and flank or abdominal pain, and included two sets of siblings. Peak creatinine levels were 2.6-17.7 mg/dL (median, 6.6 mg/dL). All patients were hospitalized; one required dialysis; none died. No alternate causes of acute kidney injury or nephrotoxins were identified. Patients reported easily purchasing synthetic cannabinoids at convenience, tobacco, and adult bookstores. One clinical and 2 product samples contained evidence of a novel synthetic cannabinoid, XLR-11 ([1-(5-fluoropentyl)-1H-indol-3-yl](2,2,3,3-tetramethylcyclopropyl)methanone).

DISCUSSION AND CONCLUSION

Whether caused by direct toxicity, genetic predisposition, or an as-yet unidentified nephrotoxin, this association between synthetic cannabinoid exposure and acute kidney injury reinforces the need for vigilance to detect new toxicologic syndromes associated with emerging drugs of abuse. Liquid chromatography and time-of-flight mass spectrometry are useful tools in determining the active ingredients in these evolving products and evaluating them for toxic contaminants.

Nonlinear modelling and control for heart rate response to exercise

In order to accurately regulate cardiovascular response to exercise for individual exerciser, this study proposes a modelling and control integrated approach based on ε-insensitive Support Vector Regression (SVR) and switching control strategy. Firstly, a control oriented modelling approach is proposed to depict nonlinear behaviours of cardiovascular response at both onset and offset of treadmill exercises by using support vector machine regression. Then, based on the established nonlinear time-variant model, a novel switching Model Predictive Control (MPC) algorithm has been proposed for the optimisation of exercise efforts. The designed controller can take into account both coefficient drifting and parameter jump by embedding the identified model coefficient into the optimiser and adopting switching strategy during the transfer between onset and offset of exercises. The effectiveness of the proposed modelling and control approach was shown from the regulation of dynamical heart rate response to exercise through simulation using MATLAB.

Modeling of a gas concentration measurement system

Energy expenditure can be calculated via measurement of oxygen consumption and carbon dioxide production. Precise measurement of expired gas concentrations and volume is required for this determination. For a given gas concentration measurement system, the establishment of a model is a good way to effectively use the equipments and achieve more accurate energy expenditure calculations. This paper proposes a simple but effective approach for the modeling of a gas concentration measurement system.

Time constant of heart rate recovery after low level exercise as a useful measure of cardiovascular fitness

In this study we aimed to establish the usefulness of the time constant of heart rate recovery (Tr) in the evaluation of cardiovascular fitness. 15 male subjects exercised on recumbent bicycle at three different workloads (75 W, 100 W 125 W) where R-R intervals were monitored to determine Tr. In order to find the maximal oxygen uptake (VO2max) of each subject, oxygen consumption rate (VO2) was recorded throughout the treadmill exercise (10 km/h). Based on VO2max, we classified the subjects into two groups: the "fit" group and the "unfit" group. We found a significant difference in Tr between these two groups only existed when the workload was 75 W (<or=0.01) and only at this workload did the R-R intervals achieve stability during the 5 minutes of exercise. Furthermore, we found the cut-off value for predicting cardiovascular fitness at this workload was 55 seconds, with an associated sensitivity of 85.7% and specificity of 87.5%

Heart rate control during treadmill exercise

A computer-controlled treadmill and related data collection and processing systems have been developed for the control of heart rate during treadmill exercise. Minimizing deviations of heart rate from a preset profile is achieved by controlling the speed and/or the gradient of the treadmill. A simple and practical heart rate measurement algorithm has been developed to robustly measure the variations of heart rate. Both conventional Proportional-Integral-Derivative (PID) control and fuzzy Proportional-Integral (PI) control approaches have been employed for the controller design. The fuzzy Proportional-Integral algorithm achieved better heart rate tracking performance. Finally, a heart rate based exercising protocol was successfully implemented on the newly designed exercise system.

Analysis of orientation error of triaxial accelerometers on the assessment of energy expenditure

This paper investigates the effects of orientation error in the positioning of triaxial accelerometers on the assessment of energy expenditure. Four subjects walked on a treadmill at varying velocities ranging from 4km.h^-1to 5km.h^-1. During each test, a triaxial accelerometer attached to the lower back at arbitrary orientations to record body accelerations. Energy expenditure was estimated by the sum of the integrals of the absolute value of accelerometer output from all the three measurement directions. Based on theoretical analysis and experimental observations, it is concluded that small orientation errors (&lt; 3&#176;) have no distinguishable effects on the estimation of energy expenditure. We propose an efficient method to compensate for larger orientation errors. The experimental results verified the effectiveness of this proposed compensation method.

Timing of ketogenic diet initiation in an experimental epilepsy model

Following kainic acid (KA)-induced status epilepticus (SE), the ketogenic diet (KD) retards the development of epileptogenesis, with fewer spontaneous recurrent seizures (SRS) and less mossy fiber sprouting than rats on a normal diet. In this study, we investigated whether there is a critical period for initiation of the KD, in terms of the diet's effectiveness in reducing SRS. In addition, we investigated whether early treatment with the KD prevents the deficits in spatial learning and memory that ordinarily follow KA-induced SE. Young rats (P30) underwent KA-induced SE, followed by assignment to one of three treatment groups: control diet ('KA'), KD begun 2 days after SE ('KD2'), and KD begun fourteen days after SE ('KD14'). For 12 weeks following SE, rats were monitored by closed circuit video recording (12 h/wk) to detect SRS. KD2 rats had significantly fewer SRS than rats in the control or KD14 groups. On water maze testing to assess spatial learning and memory, KD2 rats had significantly poorer acquisition of place learning than control (KA alone) or KD14 rats. KD2 rats also failed to gain weight well. There was no difference between groups on routine histologic examination of the hippocampus. In summary, P30 rats placed on the KD 2 days after SE were relatively protected from recurrent seizures, but showed behavioral and physical impairment. Rats placed on the KD 14 days after KA-induced SE did not differ from controls with regard to spontaneous seizure rate.

Devices for ischemic preconditioning of the pedicled groin flap

BACKGROUND

Early division of the pedicled groin flap can be achieved by using ischemic preconditioning. The goal of this study was to investigate the devices available for ischemic preconditioning and determine which device is the most effective and results in lowest patient discomfort.

METHODS

Rubber bands, custom-made Orthoplast sheets, long-nose locking pliers, intestinal clamps, and a pneumatic tourniquet device were used for ischemic preconditioning on 13 patients who sustained severe hand injuries with reconstruction of pedicled groin flaps. The devices were compared by using laser Doppler flowmetry and the patient's local pain levels.

RESULTS

Twelve of 13 flaps were successfully divided at a mean period of 8.3 days by using a custom-made Orthoplast sheet or a pneumatic tourniquet device. All devices except the rubber bands could result in a biologic zero flow level.

CONCLUSION

The pneumatic tourniquet device is the most desirable ischemic preconditioning device, having the advantages of excellent ischemic effect, easy application, and minimal discomfort.

[Detection of EBV-DNA, EBNA2 and LMP-1 in tumor tissues of han and uygur patients with nasopharyngeal carcinoma in Xinjiang]

OBJECTIVE

To investigate the possible differences of human nasopharyngeal carcinogenesis between Han and Uygur patients in xinjiang.

METHOD

Detection of EBV-DNA, EBNA2 and LMP-1 in tumor tissues of 73 patients (Han 41, uygur 32) with nasopharyngeal carcinoma (NPC) were performed by PCR and immunohistochemistry.

RESULT

Tho positive rate of EBV-DNA, EBNA2 expression was 48.2%(20/41), 43.9% (18/41) in Han and 59.3%(19/32), 43.7%(14/32) in Uygur respectively, no significant difference was found (P > 0.05). Expression of LMP-1 in NPC, in both positive and negative EBV-DNA specimens, was higher in Uygur (78.9%) than that in Han (40%) (P < 0.05),

CONCLUSION

The EBV infection may involve in nasopharyngeal carcinogenesis in xinjiang; the LMP-1 of EBV could be a more critical factor in malignant transformation of normal nasopharyngeal epithelium in uygur people than in han Chinese.

Preparation of a novel streptokinase mutant with improved stability

The novel mutant streptokinase, SK-K59E, can activate human plasminogen as efficiently as the purified commercially available streptokinase. Several peptide bonds including Lys59-Ser60 in native streptokinase were hydrolyzed in reaction with plasmin and peptides of small molecular masses were generated. The plasminogen activator activity of native streptokinase in reaction with human plasmin declined to 25% of the original activity in a 120-min incubation. On the other hand, the NH2-terminal peptide of SK-K59E remained intact in reaction with plasmin and the activator activity of streptokinase decreased to 75% of the original activity in 120 min. The major degraded peptide fragments of native streptokinase in reaction with plasmin had molecular masses of 36 and 30 kDa. However, two major peptide fragments of 42 and 34 kDa were observed in the reaction of SK-K59E with human plasmin. The 42 kDa peptide fragment, which contained NH2-terminal of streptokinase, could activate human plasminogen as efficiently as the native streptokinase. SK-K59E can induce greater degree of caseinolysis and fibrinolysis than the native streptokinase. In conclusion, the results demonstrate that the prevention of cleavage at Lys59 of streptokinase prolongs the half-life of streptokinase in complex with plasmin and that the NH2-terminal of streptokinase (Ile1-Lys59) plays an important role in maintaining its stability.

Nasopharyngeal carcinoma in young patients

We have reviewed retrospectively the records of 157 patients, less than or equal to 30 years of age with nasopharyngeal carcinoma (NPC) from 218 such cases identified in the tumor registry files of three major teaching hospitals in Taipei, Taiwan. These cases were diagnosed between 1 January 1982 and 31 December 1985, with a minimum follow-up of 2 years. The average age was 25, with a male/female ratio of 1.67. The TNM (tumor size, nodes, metastases) classification of 127 patients showed T1, 22%; T2, 33.1%; T3, 23.6%; T4, 21.3%; N0, 26%; N1, 16.5%; N2, 27.6%; N3, 30%; and M1, 13.4%. Antibody titer to Epstein-Barr virus capsular antigen (EBVCA) were elevated in 45 of 48 patients tested. Of the 29 patients who had hepatitis B (HB) viral survey done 34.5% were positive for HB surface antigen (HBsAg). Of 13 patients with elevated EBVCA antibody who were also tested for HB, six were HBsAg carrier. Actuarial survival rates of 2 and 3 years are 70 and 62%, respectively, among the 90 patients who were followed regularly or to death. HBsAg carriers and patients with M1 disease had a shorter survival time. We concluded that patients less than 30 years of age seemed to have an increased incidence of NPC, compared to that in an earlier report. Our patients frequently presented with advanced stage and poor prognosis. The high rate of HB carrier raises the possibility that HBV may play a role in the carcinogenesis and tumor growth in some NPC patients. Future prospective studies are needed.

Homology among beta-crystallins: monoclonal antibodies to beta-heavy crystallin

The mouse monoclonal antibodies, prepared with rat beta H-crystallin as parent antigen, show cross-reactivity to specific subunits in beta H-, beta L1-, and beta L2-crystallin but no reactivity to either alpha- or gamma-crystallins. Antigenic homology among the beta-crystallin subunits was demonstrated by comparison of the topographic distributions of peptides on two-dimensional electrophoretograms subjected to either staining or an ELISA of the immunoblots.

Characterization of lens proteins. IV. Analysis of soluble high molecular weight protein aggregates in human lenses

Soluble proteins of individual human normal and nuclear cataractous lenses of 60-70-year-old subjects were collected for this investigation. The average wet weights of both the normal and nuclear cataractous lenses were found to be essentially identical, approximately 230 mg. When the lens proteins, either cortical or nuclear, were subjected to fractionation by Sephadex G-200 sf chromatography, six fractions (F-I to F-VI) were obtained and their respective molecular weights approximated. F-I, which contains alpha-crystallin and high molecular weight aggregates, was subsequently fractionated through a series of Bio-gel A chromatographic columns. The quantities of the proteins and the molecular weights of each fraction were obtained. All the proteins fractionated were subjected to SDS gel electrophoresis by which the molecular weights of the subunits were obtained. The distribution and molecular weights of proteins smaller than 0.2 X 10(6) showed certain changes, more noticeable in the nucleus than in the cortex, between the normal lens and nuclear cataractous lens. For the high-molecular-weight protein aggregates, the major fraction in the lens cortex was found to be in the 5-1.5 X 10(6) range, representing 10 and 12% of the total protein in the normal and cataractous lenses, respectively. The major fraction in the nucleus was found to be greater than 150 X 10(6), representing 11 and 19% for the normal and cataractous lenses respectively. The above data are presented for the first time to show the differences in distribution of the high-molecular-weight proteins in the cortical and nuclear regions, and their respective changes in cataractogenesis. Based upon these data, we are able to calculate the average molecular weights of (1) the soluble cortical and nuclear proteins and (2) the total soluble protein, in the normal and cataractous human lenses.