Changes in plasma phenylalanine, isoleucine, leucine, and valine are associated with significant changes in intracranial pressure and jugular venous oxygen saturation in patients with severe traumatic brain injury

Changes in plasma aromatic amino acids (AAA=phenylalanine, tryptophan, tyrosine) and branched chain amino acids (BCAA=isoleucine, leucine, valine) levels possibly influencing intracranial pressure (ICP) and cerebral oxygen consumption (SjvO2) were investigated in 19 sedated patients up to 14days following severe traumatic brain injury (TBI). Compared to 44 healthy volunteers, jugular venous plasma BCAA were significantly decreased by 35% (p<0.001) while AAA were markedly increased in TBI patients by 19% (p<0.001). The BCAA to AAA ratio was significantly decreased by 55% (p<0.001) which persisted during the entire study period. Elevated plasma phenylalanine was associated with decreased ICP and increased SjvO2, while higher plasma isoleucine and leucine levels were associated with increased ICP and higher plasma leucine and valine were linked to decreased SjvO2. The amount of enterally administered amino acids was associated with significantly increased plasma levels with the exception of phenylalanine. Contrary to the initial assumption that elevated AAA and decreased BCAA levels are detrimental, increased plasma phenylalanine levels were associated with beneficial signs in terms of decreased ICP and reduced cerebral oxygen consumption reflected by increased SjvO2; concomitantly, elevated plasma isoleucine and leucine levels were associated with increased ICP while leucine and valine were associated with decreased SjvO2 following severe TBI, respectively. The impact of enteral nutrition on this observed pattern must be examined prospectively to determine if higher amounts of phenylalanine should be administered to promote beneficial effects on brain metabolism and if normalization of plasma BCAA levels is without cerebral side effect

Kidney amino acid transport

Near complete reabsorption of filtered amino acids is a main specialized transport function of the kidney proximal tubule. This evolutionary conserved task is carried out by a subset of luminal and basolateral transporters that together form the transcellular amino acid transport machinery similar to that of small intestine. A number of other amino acid transporters expressed in the basolateral membrane of proximal kidney tubule cells subserve either specialized metabolic functions, such as the production of ammonium, or are part of the cellular housekeeping equipment. A new finding is that the luminal Na+-dependent neutral amino acid transporters of the SLC6 family require an associated protein for their surface expression as shown for the Hartnup transporter B0AT1 (SLC6A19) and suggested for the l-proline transporter SIT1 (IMINOB, SLC6A20) and for B0AT3 (XT2, SLC6A18). This accessory subunit called collectrin (TMEM27) is homologous to the transmembrane anchor region of the renin-angiotensin system enzyme ACE2 that we have shown to function in small intestine as associated subunit of the luminal SLC6 transporters B0AT1 and SIT1. Some mutations of B0AT1 differentially interact with these accessory subunits, providing an explanation for differential intestinal phenotypes among Hartnup patients. The basolateral efflux of numerous amino acids from kidney tubular cells is mediated by heteromeric amino acid transporters that function as obligatory exchangers. Thus, other transporters within the same membrane need to mediate the net efflux of exchange substrates, controlling thereby the net basolateral amino transport and thus the intracellular amino acid concentratio

Anatomy of the neural fibers at the superior mesenteric artery-a cadaver study

PURPOSE Most surgeons perform right-sided semicircular clearance of the superior mesenteric artery (SMA) nerve plexus for pancreatic head carcinoma, presuming a linear course of the SMA nerve fibers. The hypothesis was that the SMA nerve plexus fibers follow a non-linear course, and the goal of the present study was to assess the neural fibers distribution along the SMA. METHODS The course of neural fibers along the retropancreatic and suprapancreatic SMA was assessed in 7 cadavers. RESULTS In the retropancreatic course of the vessel, the main nerve cords branch and form a large number of finer nerve branches performing an anti-clockwise rotation of slightly less than 90° around the SMA. Finer nerve branches are located rather close to the vessel, while the main nerve cords are localized in the loose connective tissue of the peripheral parts of the vascular sheath. Nerve fibers around the suprapancreatic SMA run as two main nerve cords framing the artery on the right lateral-ventral and the left lateral to lateral-dorsal side. CONCLUSION The rotation of the nerve fiber around the SMA indicates that a more radical resection of at least 180° of neural tissue around the SMA might be required to achieve tumor clearance in pancreatic cancer with perineural invasion at the uncinate margin

Extended lymph node resection versus standard resection for pancreatic and periampullary adenocarcinoma

BACKGROUND Pancreatic and periampullary adenocarcinomas account for some of the most aggressive malignancies, and the leading causes of cancer-related mortalities. Partial pancreaticoduodenectomy (PD) with negative resection margins is the only potentially curative therapy. The high prevalence of lymph node metastases has led to the hypothesis that wider excision with the removal of more lymphatic tissue could result in an improvement of survival, and higher rates of negative resection margins. OBJECTIVES To compare overall survival following standard (SLA) versus extended lymph lymphadenectomy (ELA) for pancreatic head and periampullary adenocarcinoma. We also compared secondary outcomes, such as morbidity, mortality, and tumour involvement of the resection margins between the two procedures. SEARCH METHODS We searched CENTRAL, MEDLINE, PubMed, and Embase from 1973 to September 2020; we applied no language restrictions. SELECTION CRITERIA Randomised controlled trials (RCT) comparing PD with SLA versus PD with ELA, including participants with pancreatic head and periampullary adenocarcinoma. DATA COLLECTION AND ANALYSIS Two review authors independently screened references and extracted data from study reports. We calculated pooled risk ratios (RR) for most binary outcomes except for postoperative mortality, for which we estimated a Peto odds ratio (Peto OR), and mean differences (MD) for continuous outcomes. We used a fixed-effect model in the absence of substantial heterogeneity (I² 25%). Two review authors independently assessed risk of bias, and we used GRADE to assess the quality of the evidence for important outcomes. MAIN RESULTS We included seven studies with 843 participants (421 ELA and 422 SLA). All seven studies included Kaplan-Meier curves for overall survival. There was little or no difference in survival between groups (log hazard ratio (log HR) 0.12, 95% confidence interval (CI) -3.06 to 3.31; P = 0.94; seven studies, 843 participants; very low-quality evidence). There was little or no difference in postoperative mortality between the groups (Peto odds ratio (OR) 1.20, 95% CI 0.51 to 2.80; seven studies, 843 participants; low-quality evidence). Operating time was probably longer for ELA (mean difference (MD) 50.13 minutes, 95% CI 19.19 to 81.06 minutes; five studies, 670 participants; moderate-quality evidence). There was substantial heterogeneity between the studies (I² = 88%; P < 0.00001). There may have been more blood loss during ELA (MD 137.43 mL, 95% CI 11.55 to 263.30 mL; two studies, 463 participants; very low-quality evidence). There was substantial heterogeneity between the studies (I² = 81%, P = 0.02). There may have been more lymph nodes retrieved during ELA (MD 11.09 nodes, 95% CI 7.16 to 15.02; five studies, 670 participants; moderate-quality evidence). There was substantial heterogeneity between the studies (I² = 81%, P < 0.00001). There was little or no difference in the incidence of positive resection margins between groups (RR 0.81, 95% CI 0.58 to 1.13; six studies, 783 participants; very low-quality evidence). AUTHORS' CONCLUSIONS There is no evidence of an impact on survival with extended versus standard lymph node resection. However, the operating time may have been longer and blood loss greater in the extended resection group. In conclusion, current evidence neither supports nor refutes the effect of extended lymph lymphadenectomy in people with adenocarcinoma of the head of the pancreas

Microbial Colonization From the Fetus to Early Childhood—A Comprehensive Review

The development of the neonatal gastrointestinal tract microbiota remains a poorly understood process. The interplay between neonatal (gestational age, genetic background), maternal (mode of delivery, nutritional status) and environmental factors (antibiotic exposure, available nutrition) are thought to influence microbial colonization, however, the exact mechanisms are unclear. Derangements in this process likely contribute to various gastrointestinal diseases including necrotizing enterocolitis and inflammatory bowel disease. As such, enhanced understanding of microbiota development may hold the key to significantly reduce the burden of gastrointestinal disease in the pediatric population. The most debatable topics during microbial seeding and possible future treatment approaches will be highlighted in this review

SARS-CoV-2 receptor ACE2 gene expression in small intestine correlates with age

Gastrointestinal symptoms are common in COVID-19 patients, especially in younger patients. Our hypothesis was that intestinal SARS-CoV-2 receptor ACE2 expression depends on patients' age. We examined duodenal biopsies from 43 healthy human adults. ACE2 gene expression was directly correlated with age (Spearman's r = 0.317, p = 0.039). With each year, duodenal ACE2 expression increased by 0.083 RU. The higher intestinal ACE2 mRNA expression in older patients may impact on their susceptibility to develop intestinal symptoms

Statistics decrypted-a comprehensive review and smartphone-assisted five-step approach for good statistical practice

BACKGROUND Statistic scripts are often made by mathematicians and cryptic for clinicians or non-mathematician scientists. Nevertheless, almost all research projects necessitate the application of some statistical tests or at least an understanding thereof. The present review aims on giving an overview of the most common statistical terms and concepts. It further ensures good statistical practice by providing a five-step approach guiding the reader to the correct statistical test. METHODS AND RESULTS First, different types of variables and measurements to describe a data set with means of descriptive statistics are introduced. The basic thoughts and tools of interferential statistics are presented, and different types of bias are discussed. Then in the final paragraph, the most commonly used statistical tests are described. A smartphone app accessible via QR code finally guides the reader in five steps to the correct statistical test, depending on the data used in order to avoid commonly performed mistakes. CONCLUSIONS The five-step approach sets a new minimal standard for good statistical practice