Bioindicators of severe ocean acidification are absent from the end-Permian mass extinction.

The role of ocean acidification in the end-Permian mass extinction is highly controversial with conflicting hypotheses relating to its timing and extent. Observations and experiments on living molluscs demonstrate that those inhabiting acidic settings exhibit characteristic morphological deformities and disordered shell ultrastructures. These deformities should be recognisable in the fossil record, and provide a robust palaeo-proxy for severe ocean acidification. Here, we use fossils of originally aragonitic invertebrates to test whether ocean acidification occurred during the Permian-Triassic transition. Our results show that we can reject a hypothesised worldwide basal Triassic ocean acidification event owing to the absence of deformities and repair marks on bivalves and gastropods from the Triassic Hindeodus parvus Conodont Zone. We could not, however, utilise this proxy to test the role of a hypothesised acidification event just prior to and/or during the mass extinction event. If ocean acidification did develop during the mass extinction event, then it most likely only occurred in the latest Permian, and was not severe enough to impact calcification.

Refeeding Syndrome in the Critically Ill: a Literature Review and Clinician's Guide.

PURPOSE OF REVIEW: To provide an overview of current methods of diagnosis and management of refeeding syndrome in the critically ill patient population. RECENT FINDINGS: Despite recent publications indicating refeeding syndrome (RFS) is an ongoing problem in critically ill patients, there is no standard for the diagnosis and management of this life-threatening condition. There is not a "gold standard" nutrition assessment tool for the critically ill. Currently, the National Institute for Health and Clinical Excellence criteria represent the best clinical assessment tool for RFS. Diagnosis and management with the help of a multidisciplinary metabolic team can decrease morbidity and mortality. Although a universal definition of RFS has yet to be defined, the diagnosis is made in patients with moderate to severe malnutrition who develop electrolyte imbalance after beginning nutritional support. The imbalances potentially can lead to cardiac, pulmonary, and gastrointestinal complications and failure. Standardizing a multidisciplinary nutrition care plan and formulating a protocol for critically ill patients who develop RFS can potentially decrease complication rates and overall mortality.

Sarcopenia and outcomes in ventral hernia repair: a preliminary review.

PURPOSE: Sarcopenia, or loss of muscle mass, is associated with increased morbidity and mortality in oncologic resections and several other major surgeries. Complex ventral hernia repairs (VHRs) and abdominal wall reconstruction are often performed in patients at high risk for morbidity and recurrence, though limited data exist on outcomes related to sarcopenia. We aimed to determine if sarcopenia is associated with worse outcomes in patients undergoing VHR. METHODS: We reviewed patients undergoing VHRs from 2014 to 2015. Preoperative CT images were analyzed for cross-sectional muscle mass. Patients with and without sarcopenia underwent statistical analysis to evaluate differences in perioperative morbidity and hernia recurrence. Muscle indices were analyzed independently for outcomes. RESULTS: 135 patients underwent VHR with/without fistula takedown, staged repairs or other concomitant procedures. 27% had sarcopenia (age 34-84, BMI 27-33, 62% male). Postoperative complications occurred in 43% of sarcopenic patients and 47% of non-sarcopenic patients (p = 0.70). Surgical site infections (SSI) were seen in 16% of sarcopenic patients compared to 29% without sarcopenia (p = 0.14). There was no difference in hernia recurrence between groups (p = 0.90). However, after adjusting for diabetes and BMI, a 10 cm2/m2 decrease in muscle index had 1.44 OR of postoperative complications (p < 0.05). CONCLUSIONS: Though prevalent in our population, sarcopenia was not associated with an increase in postoperative complications, surgical site occurences/infections,  or hernia recurrence when previously published oncologic sarcopenia cutoffs were utilized. Previously established sarcopenia outcomes in malignancy may be attributable to an altered metabolic state that is not present in hernia repair patients. Larger-scale studies are recommended to establish new sarcopenia cutoffs for VHRs.

Early report of a randomized comparative clinical trial of Strattice™ reconstructive tissue matrix to lightweight synthetic mesh in the repair of inguinal hernias.

PURPOSE: Biologic grafts are rarely used for inguinal herniorrhaphy. The aim of this study was to compare the clinical outcomes between patients undergoing a Lichtenstein's hernioplasty with a porcine mesh versus a standard synthetic. METHODS: A prospective, randomized, double-blinded multicenter, evaluation of inguinal hernia repair was conducted between 2008 and 2010. Lichtenstein hernioplasty was performed using Strattice™ or lightweight polypropylene (Ultrapro) mesh. Quality of life, pain, overall complication rate, and recurrence were measured. RESULTS: One hundred and seventy-two patients were randomized to Strattice™ (n = 84) or Ultrapro (n = 88). At 3 months postoperatively, there were no differences on the occurrence or type of wound events [RR: 0.98 (95% CI 0.52-1.86, p = 0.69), Strattice™ (15 events) vs. Ultrapro (16 events)]. The mean level of impairment caused by the hernia, assessed by Activities Assessment Scale (AAS), significantly decreased postoperatively in both groups at 3 months (31% Strattice™ and 37% Ultrapro). Patients in the Strattice group reported significantly less postoperative pain during postoperative days 1 through 3 compared to Ultrapro patients. However, the amount of postoperative pain at 3 months, as assessed by the mean worst pain score on a visual analog scale and the Brief Pain Index, was similar between groups (95% CI 1.0-29.3). No hernia recurrences were observed in either group. CONCLUSIONS: Strattice™ is safe and effective in repairing inguinal hernia, with comparable intra-operative and early postoperative morbidity to synthetic mesh. Long-term follow-up is necessary in order to know whether the clinical outcomes of Strattice are equivalent to standard synthetic mesh in patients undergoing Lichtenstein's hernioplasty.

Guidelines for nutrition therapy in critical illness: are not they all the same?

In general, clinical guidelines identify, summarize, and evaluate the most current data concerning prevention, diagnosis, prognosis, therapy and cost for a specific patient population. This paper will briefly describe the authors' point of view regarding controversial aspects of adult critical care nutrition therapy guidelines published by preeminent professional societies in the United States (US), Canada, and Europe. The US guidelines were developed by subject matter experts to offer recommendations for specialized nutrition therapy that are supported by review and analysis of the pertinent current literature, other national and international guidelines, and by a blend of expert opinion and clinical practicality. A similar strategy was used to compile all three guideline publications resulting in many areas of common agreement, but disparate substantive recommendations do exist regarding: indirect calorimetry versus predictive equations, prokinetics in the intensive care unit (ICU), arginine use in the ICU, probiotic use in the ICU, and acceptable gastric residual volumes in the ICU patient. All of the guidelines are based on high quality studies in patients with critical illness, but like any other therapeutic modality for an ICU patient, nutritional interventions require a multidisciplinary approach that incorporates institutional best practices, individual patient considerations, and above all, clinical judgment.

The increased incidence of intraabdominal infections in laparoscopic procedures: potential causes, postoperative management, and prospective innovations.

We conducted a review of the literature to identify some potential causes for the increased incidence of intraabdominal infections seen after laparoscopic procedures. We also discuss the postoperative management of this condition and provide a prospective overview of innovations that may be helpful in such cases in the future.

Fit for surgery: an expert panel review on optmising patients prior to surgery, with a particular focus on nutrition.

This article represents the views of an international group of surgeons on the need for pre-operative optimisation of patient's nutritional status prior to elective surgery as a means of reducing post-operative infective complications.

When a hernia is not a hernia: the evaluation of inguinal hernias in the cirrhotic patient.

Herniorrhapy in patients with advanced portal hypertension and ascites should be approached with caution, and treated conservatively whenever possible. Cirrhosis increases the risk of significant perioperative complications such as infection, recurrence, and ascites leak. This paper reports two patients operated on for suspected inguinal hernias. The first patient was referred for elective repair of a presumed inguinal hernia before liver transplantation. The second patient presented with a history of an incarcerated inguinal hernia that was previously reduced in the emergency center. After examination by residents and senior faculty the patients were scheduled for elective herniorrhaphy. Intraoperatively no inguinal hernia could be identified in either patient. However, massively dilated veins (1.5-2.0 cm in diameter) were noted entering with the spermatic cord at the internal inguinal ring. In both cases the veins were clamped, transected, and suture ligated at the internal ring. Given the unusual presentation of these dilated veins in both patients we advocate the use of preoperative Doppler ultrasound in patients with cirrhosis and suspected inguinal hernias.

The gastrointestinal tract in critical illness.

The gut has often been suggested to be one of the essential factors in the pathogenesis of many nosocomial infections and possibly multi-organ failure. In the light of several recent studies, the importance of normal gut bacterial flora and the role of the gastrointestinal tract in human immune function are now better understood. It now seems clear that stimulation of gut-associated lymphoid tissue through enteral feeding is the key to the preservation of mucosal-derived immunity; however, the role of this native gastrointestinal immune function in the subsequent development of sepsis and multi-organ dysfunction syndrome remains the subject of ongoing study.

Cloning and functional characterization of a new subtype of the amino acid transport system N.

We have cloned a new subtype of the amino acid transport system N2 (SN2 or second subtype of system N) from rat brain. Rat SN2 consists of 471 amino acids and belongs to the recently identified glutamine transporter gene family that consists of system N and system A. Rat SN2 exhibits 63% identity with rat SN1. It also shows considerable sequence identity (50-56%) with the members of the amino acid transporter A subfamily. In the rat, SN2 mRNA is most abundant in the liver but is detectable in the brain, lung, stomach, kidney, testis, and spleen. When expressed in Xenopus laevis oocytes and in mammalian cells, rat SN2 mediates Na(+)-dependent transport of several neutral amino acids, including glycine, asparagine, alanine, serine, glutamine, and histidine. The transport process is electrogenic, Li(+) tolerant, and pH sensitive. The transport mechanism involves the influx of Na(+) and amino acids coupled to the efflux of H(+), resulting in intracellular alkalization. Proline, alpha-(methylamino)isobutyric acid, and anionic and cationic amino acids are not recognized by rat SN2.

Differential influence of cAMP on the expression of the three subtypes (ATA1, ATA2, and ATA3) of the amino acid transport system A.

Treatment of HepG2 cells with forskolin led to 60-100% stimulation of system A activity, measured as the Na+-dependent uptake of alpha-(methylamino)isobutyric acid. The stimulation was reproducible with cholera toxin and dibutyryl cAMP, and inhibitable by H7, a non-specific protein kinase inhibitor. The stimulatory effect was eliminated by cycloheximide and actinomycin D. The forskolin effect was associated with an increase in the maximal velocity of the transport system, with no change in substrate affinity. These cells express three different subtypes of system A (ATA1, ATA2, and ATA3). Treatment with forskolin increased the steady-state levels of ATA1 and ATA2 mRNAs, but decreased that of ATA3 mRNA.

Solitary fibrous tumors arising in abdominal wall hernia sacs.

Solitary fibrous tumor (SFT) of the peritoneum is an unusual spindle-cell neoplasm. SFT was originally described in the pleura; however it is now diagnosed in multiple extrathoracic sites. Most believe that the tumor is of mesenchymal origin and should be classified as a variant of fibroma. SFT of the pleura and peritoneum have also been called fibrous mesothelioma, and the cell of origin is felt to be a pluripotential submesothelial mesenchymal cell. Primary tumors arising in hernia sacs are rare, and we report on two patients with hernia SFT. The first is a 67-year-old man who had a diffusely thickened distal left inguinal hernia sac. Within the sac was copious myxoid material mimicking pseudomyxoma peritonei. Herniorrhaphy and orchiectomy were performed. The second is a 44-year-old woman with a midepigastric mass attached to a ventral hernia. Wide local excision was performed. Both tumors demonstrated plump spindle cells, one with myxoid background and the other with keloidal collagen. Calretinin immunostaining was positive in both tumors, whereas CD34 was negative. This suggests tumor origin from a submesothial pluripotential cell that maintains potential for mesothelial differentiation. Surgical excision is the treatment of choice with the degree of resectability being a powerful predictor of outcome.

Typical versus atypical presentation of obturator hernia.

Although it is a rare occurrence among all pelvic hernias diagnosed the obturator hernia continues to be a diagnostic challenge for surgeons today. These patients, who often have multiple concurrent medical problems, are subject to high morbidity and mortality rates resulting from late presentation and delayed surgical intervention. The vast majority of patients with obturator hernias are admitted with signs and symptoms of intestinal obstruction, namely anorexia, nausea, vomiting, constipation, and distension of 2 to 3 days' duration. In this paper, however, we highlight a small subset of obturator hernia patients who present without obstructive symptoms and do well after elective repair. The case reports that follow serve to compare and contrast two very different presentations of this surgical problem.

Structure, function, and tissue expression pattern of human SN2, a subtype of the amino acid transport system N.

We have cloned a new subtype of the amino acid transport system N from a human liver cell line. This transporter, designated SN2, consists of 472 amino acids and exhibits 62% identity with human SN1 at the level of amino acid sequence. SN2-specific transcripts are expressed predominantly in the stomach, brain, liver, lung, and intestinal tract. The sizes of the transcripts vary in different tissues, indicating tissue-specific alternative splicing of the SN2 mRNA. In contrast, SN1 is expressed primarily in the brain and liver and there is no evidence for the presence of multiple transcripts of varying size for SN1. When expressed in mammalian cells, the cloned human SN2 mediates Na(+)-coupled transport of system N-specific amino acid substrates (glutamine, asparagine, and histidine). In addition, SN2 also transports serine, alanine, and glycine. Anionic amino acids, cationic amino acids, imino acids, and N-alkylated amino acids are not recognized as substrates by human SN2. The SN2-mediated transport process is Li(+)-tolerant and highly pH-dependent. The Michaelis-Menten constant for histidine uptake via human SN2 is 0.6 +/- 0.1 mM. The gene coding for SN2 is located on human chromosome Xp11.23. Successful cloning of SN2 provides the first molecular evidence for the existence of subtypes within the amino acid transport system N in mammalian tissues.

Structure and function of ATA3, a new subtype of amino acid transport system A, primarily expressed in the liver and skeletal muscle.

To date, two different transporters that are capable of transporting alpha-(methylamino)isobutyric acid, the specific substrate for amino acid transport system A, have been cloned. These two transporters are known as ATA1 and ATA2. We have cloned a third transporter that is able to transport the system A-specific substrate. This new transporter, cloned from rat skeletal muscle and designated rATA3, consists of 547 amino acids and has a high degree of homology to rat ATA1 (47% identity) and rat ATA2 (57% identity). rATA3 mRNA is present only in the liver and skeletal muscle. When expressed in Xenopus laevis oocytes, rATA3 mediates the transport of alpha-[(14)C](methylamino)isobutyric acid and [(3)H]alanine. With the two-microelectrode voltage clamp technique, we have shown that exposure of rATA3-expressing oocytes to neutral, short-chain aliphatic amino acids induces inward currents. The amino acid-induced current is Na(+)-dependent and pH-dependent. Analysis of the currents with alanine as the substrate has shown that the K(0. 5) for alanine (i.e., concentration of the amino acid yielding half-maximal current) is 4.2+/-0.1 mM and that the Na(+):alanine stoichiometry is 1:1.

Glutamine and the gastrointestinal tract.

The amino acid glutamine has become one of the most intensively studied nutrients in the field of nutrition and metabolic support. A variety of studies in cell culture systems, animal models of gut mucosal atrophy, injury/repair and adaptation and a limited number of clinical trials demonstrate trophic and cytoprotective effects of glutamine in small bowel and colonic mucosal cells. Although the routine clinical use of glutamine-enriched parenteral and enteral nutrient solutions remains controversial, available data demonstrate both the safety and metabolic and clinical efficacy of glutamine treatment in selected patient groups. Basic investigations are elucidating underlying mechanisms of glutamine action in intestinal cells. These will inform preclinical and clinical investigations designed to determine glutamine efficacy in selected gastrointestinal disorders. Emerging clinical trials will further define the utility of adjunctive glutamine supplementation as a component of specialized nutrition support in gastrointestinal disease.