Theoretical analysis of surface EMG in voluntary isometric contraction

Summary A new stochastic model of the surface EMG is suggested and the spectral density of the surface EMG is studied theoretically and experimentally to confirm the validity of this model.Theoretical results show that while the contraction level is not so high, the shape of the spectral density (distribution) does not change and its amplitude is directly proportional to the motor unit firing frequency and recruitment.To illustrate the theoretical results, experiments were carried out for rectus femoris and biceps brachii. The surface EMG was lead off by bipolar surface electrodes. And the spectral density of the surface EMG was calculated using FFT algorithm.From these experimental results, it was confirmed that our theoretical results were almost valid.     

Lessons learned from lower urinary tract complications of anorectoplasty for imperforate anus with rectourethral/rectovesical fistula: Laparoscopy-assisted versus posterior sagittal approaches

PurposeTo report the sequelae of and preventive strategies for selected lower urinary tract (LUT) complications, i.e., posterior urethral diverticulum (PUD), intraoperative LUT injuries, postoperative dysuria, and fistula recurrence in male imperforate anus (IA) with rectourethral/rectovesical (RU/RV) fistula after laparoscopy-assisted anorectoplasty (LAARP) or posterior sagittal anorectoplasty (PSARP).Methods153 boys with IA and RU/RV fistula treated 1986–2019 by LAARP (n = 56) or PSARP (n = 97) at two unrelated institutes were studied retrospectively.ResultsAfter mean follow-up of 17.0 years (range: 36.5 days-32.0 years), the overall incidences of LUT complications were: LAARP (6/56; 10.7%); PSARP (7/97; 7.2%); p = 0.55, comprising PUD: LAARP (n = 5), PSARP (n = 0); p = 0.006; injuries: LAARP (n = 0), PSARP (n = 5); p = 0.16; dysuria: LAARP (n = 1), PSARP (n = 1); p>0.999; and recurrence: LAARP (n = 0), PSARP (n = 1); p>0.999. Mean onset of PUD was 5.1 years (range: 1.0–15.1 years). Treatment: PUD: surgery (n = 2/5), conservative (n = 3/5); injuries: intraoperative repair (n = 5/5); dysuria: conservative (n = 2/2), and recurrence: redo PSARP (n = 1/1).ConclusionsStrategies devised to improve dissection accuracy resolved the specific technical issues causing LUT complications (remnant RU fistula dissection in LAARP and blind posterior access in PSARP). Currently, the incidence of new cases of PUD and LUT injuries is zero.Level of Evidence: Level III     

Hyaluronic acid: a specific prognostic indicator of hepatic damage in biliary atresia

BACKGROUND/PURPOSE: Hepatic fibrosis can progress in biliary atresia (BA) and is associated with capillarization of hepatic sinusoids. The significance of serum hyaluronic acid (HA) as a noninvasive indicator of histological sinusoidal endothelial cell (SEC) damage and hepatic fibrosis in BA, is investigated. METHODS: A total of 28 postoperative BA patients (mean age, 11.0+/-3.7 years) and 20 normal controls (mean age, 10.5+/-2.8 years) were studied. BA patients were divided into group I, good liver function (n = 8); group II, moderate liver dysfunction (n = 10); and group III, severe liver dysfunction (n = 10). Serum HA was determined using a one-step sandwich enzyme immunoassay, and liver histological damage was confirmed immunohistochemically using an antibody against factor VIII-related antigen (FVIIIRAg), which is specific for detecting damaged SEC. RESULTS: Serum HA was significantly higher (P < .0001) in group III (84.6+/-36.5 ng/mL) than in group I (15.9+/-6.9 ng/mL) or group 11 (28.7+/-10.7 ng/mL). Although immunoreactive products of FVIIIRAg were abundant in group III, they were not detected in SEC from group II. CONCLUSION: Serum HA may be of value for monitoring postoperative BA patients as a noninvasive indicator of SEC damage and progressive hepatic fibrosis.     

Serum IFN-inducible protein-10: a new clinical prognostic predictor of hepatocyte death in biliary atresia

PURPOSE: The aim of this study was to determine whether chemokines such as serum IP-10 levels in patients with biliary atresia (BA) correlate with liver function and histology and assess its value as a medium to long-term prediction of prognosis in postoperative BA patients. METHODS: Thirty postoperative BA patients (mean age, 10.8+/-3.5 years) and eight normal controls (mean age, 10.3+/-3.3 years) were studied. The BA patients were divided into three groups according to liver function. Group I (n = 8) was jaundice free, had normal liver function and no evidence of severe cholangitis or portal hypertension. Group II (n = 12) had moderate liver dysfunction. Group III (n = 10), had severe liver dysfunction. Hepatic histology was assessed using conventional needle biopsy. Serum IP-10 levels were determined using a specific enzyme-linked immunosorbent assay (ELISA). RESULTS: Serum levels of IP-10 in group III (458.0+/-240.0 pg/mL) were significantly higher than those in group II (233.6+/-126.9 pg/mL; P < .0001). Levels in group II were also significantly higher than those in group I (144.8+/-23.4 pg/mL; P < .05), but there was no significant difference between group I and controls (107.9+/-34.0 pg/mL). Liver biopsy findings showed a progression of fibrosis and mononuclear cell infiltration from group I to group III. There was intimal hyperplasia and swelling of endothelial cells of branches of the hepatic artery in the portal area in group III. CONCLUSION: Because IP-10 levels correlate closely with histological findings in postoperative BA patients, it would appear to play a specific role in hepatocyte death and hepatic artery changes, thus providing important information about progressive fibrosis in BA patients that facilitates treatment decision making and prediction of prognosis.     

Nitric oxide inhalation as a chemical assist for circulation in patients after cardiovascular surgery

The objective of this study was to investigate whether nitric oxide (NO) inhalation might be an alternative strategy as a chemical assist for the circulation in patients showing a deterioration in oxygen delivery. Twelve adult patients whose oxygen delivery indices (DO2I) were less than 400 ml/min/m2 after cardiovascular surgery were included in this study. NO was administered via a premixing system or a side stream system at doses between 1 and 10 (5.1+/-2.4) ppm. Data obtained before and during a 120 min NO inhalation were compared using the paired Student's t-test. The increase in PaO2/FiO2 resulting from NO inhalation was significant (from 162 to 251 mm Hg). DO2I increased significantly from 326 to 417 ml/min/m2 concomitantly with significant increases in both arterial oxygen content (CaO2) and cardiac index (CI) (from 14.1 to 15.4 vol% and from 2.31 to 2.71 L/min/m2 , respectively). The increase in SvO2 during NO inhalation was significant (from 55.2 to 62.6%). Among the other hemodynamic parameters, both total pulmonary resistance and systolic pulmonary arterial pressure (SPAP) showed significant decreases during NO inhalation, but right atrial pressure did not change significantly. There was a close relationship between the baseline SPAP level (bSPAP) and the decrease in SPAP during NO inhalation (dSPAP) (r = -0.88). However, negative correlations were observed between bSPAP and percentage increase in CI (%CI) (r = -0.61) and between bSPAP and percentage increase in DO2I (%DO2I) (r = -0.48). Moreover, positive relationships were observed between dSPAP and %CI (r = 0.62) and between dSPAP and %DO2I (r = 0.45). Hemoglobin (Hb) increased significantly from 11.0 to 11.4 g/dl. There were no significant changes in Fio2, pH, PacO2, or base excess (BE) during NO inhalation. The level of methemoglobin measured during the study period remained within the normal range (0.86+/-0.23%). In conclusion, NO inhalation could be an efficient and alternative assist for the circulation in patients whose oxygen delivery deteriorates after cardiovascular surgery.     

The studies of hemodynamic changes and liver uptake in a combination of ATP stress test and low workload exercise test on myocardial scintigraphy

A pharmacological adenosine-tri-phosphoric acid (ATP) stress test has been used in patients who can not perform an enough exercise stress test. However, falling blood pressure during the stress test and increased liver uptake of the tracer are often found in patients undergoing the ATP test. To prevent these phenomena, a combination of ATP stress test and low workload exercise test (ATP & EX) is proposed. The usefulness of this newly developed stress test was elucidated from two viewpoints. Firstly, the changes of hemodynamic parameters were measured in 34 patients: 17 undergoing ATP alone and 17 undergoing ATP & EX. Systolic blood pressure fell from 150 +/- 20 mmHg to 126 +/- 16 mmHg (p < 0.05) for ATP alone. However, it changed from 141 +/- 19 mmHg to 149 +/- 31 mmHg (ns) for ATP & EX. There was a significant fall in systolic blood pressure (> 30 mmHg) in 58.8% for ATP alone and 5.9% for ATP & EX (p < 0.01). Secondly, the ROI count in the liver and heart on an anterior projection image were measured in 38 patients: 11 undergoing ATP alone, 13 undergoing ATP & EX, and 14 undergoing an ergometer exercise test (EX). The ROI count in the liver at 60 minutes after tracer injection were 29.0 +/- 10.7 count/pixel, 21.4 +/- 5.2 count/pixel, 18.3 +/- 4.5 count/pixel for ATP alone, ATP & EX and EX, respectively. The activities for ATP & EX and EX were lower than that for ATP alone (p < 0.05 and p < 0.01). Thus, ATP & EX decreased the rates of the fall of systolic blood pressure and decreased liver uptake of the tracer compared with ATP alone. In conclusion, ATP & EX is a useful stress method for myocardial perfusion scintigraphy in patients who can not perform the enough exercise stress test.     

Psoas abscess: diagnostic and therapeutic considerations in six patients

Psoas abscess (PA) is an infrequent clinical entity and presents diagnostic and therapeutic challenges. Six cases are reported concerning diagnostic and therapeutic considerations. Clinical diagnosis is difficult because of non-specific symptoms. The primary psoas abscess has no definite etiology and is spread by hematogeneous route from a distant occult site. The PA can also be secondary to gastrointestinal pathology through direct infection of adjacent structures. The most common causes are Crohn's disease, appendicitis, diverticulitis and carcinoma. Routine laboratory evaluation is seldom useful for localizing the disease process. Conventional radiological techniques are often unhelpful. Modern imaging diagnosis techniques such as ultrasound and computerized tomography have allowed for a refinement in both the etiologic diagnosis and the treatment by means of CT-guided or ultrasound-guided percutaneous drainage of the abscess, thus avoiding surgical drainage in many cases. Immediately on diagnosis of PA prompt treatment is necessary. Percutaneous drainage should be performed whenever possible and in case of failure, surgical drainage should be practiced as well as intestinal resection, whenever indicated.