Flow Secretion Research Articles

PI3K-AKT activation resculpts integrin signaling to drive filamentous tau-induced proinflammatory astrogliosis

BackgroundMicrotubule-binding protein tau is a misfolding-prone protein associated with tauopathies. As tau undergoes cell-to-cell transmission, extracellular tau aggregates convert astrocytes into a pro-inflammatory state via integrin activation, causing them to release unknown neurotoxic factors.ResultsHere, we combine transcriptomics with isotope labeling-based quantitative mass spectrometry analysis of mouse primary astrocyte secretome to establish PI3K-AKT as a critical differentiator between pathogenic and physiological integrin activation; simultaneous activation of PI3K-AKT and focal adhesion kinase (FAK) in tau fibril-treated astrocytes changes the output of integrin signaling, causing pro-inflammatory gene upregulation, trans-Golgi network restructuring, and altered secretory flow. Furthermore, NCAM1, as a proximal signaling component in tau-stimulated integrin and PI3K-AKT activation, facilitates the secretion of complement C3 as a main neurotoxic factor. Significantly, tau fibrils-associated astrogliosis and C3 secretion can be mitigated by FAK or PI3K inhibitors.ConclusionsThese findings reveal an unexpected function for PI3K-AKT in tauopathy-associated reactive astrogliosis, which may be a promising target for anti-inflammation-based Alzheimer’s therapy.

The pancreatic exocrine function in patients with pancreatic endocrine insufficiency: the evaluation with cine-dynamic magnetic resonance cholangiopancreatography using a spatially selective inversion-recovery pulse and T1 mapping

PurposeTo evaluate the association of the pancreatic exocrine function estimated by cine-dynamic magnetic resonance cholangiopancreatography (MRCP) using a spatially selective inversion-recovery (IR) pulse with the pancreatic endocrine function estimated by the T1 relaxation time of the pancreatic parenchyma and HbA1c values.Materials and methodsForty-three patients with suspected hepatobiliary or pancreatic diseases were included. Patients were classified into three groups: HbA1c < 5.7% (normal group), 5.7% ≤ HbA1c < 6.5% (prediabetes group), and HbA1c ≥ 6.5% (diabetes group). The frequency of the secretory flow of the pancreatic juice was observed within the area of the IR pulse, and the moving distance (mean secretion grade) of the pancreatic juice inflow within the area of the IR pulse on cine-dynamic MRCP, and the T1 relaxation time of the pancreatic parenchyma on the T1 map images were assessed. The MR imaging measurements were compared using Spearman’s rank correlation coefficient analysis and the Kruskal–Wallis and Mann–Whitney U tests.ResultsBoth the mean secretion grade and frequency of the pancreatic secretory inflow had a significant negative correlation with the T1 relaxation time of the pancreatic parenchyma (r = − 0.335, p = 0.028 and r = − 0.305, p = 0.047, respectively) and HbA1c values (r = − 0.308, p = 0.044 and r = − 0.313, p = 0.041, respectively). Both the mean secretion grade and frequency of the pancreatic secretory inflow in the elevated HbA1c (prediabetes and diabetes) group were significantly lower than those in the normal group (p = 0.030 and p = 0.029, respectively).ConclusionThe pancreatic exocrine function estimated by cine-dynamic MRCP was significantly lower in patients with prediabetes and diabetes than in controls. Cine-dynamic MRCP with a spatially selective IR pulse may be useful for the early diagnosis of pancreatic exocrine insufficiency in patients with pancreatic endocrine insufficiency.

A novel diagnostic technique of measuring labial minor salivary gland secretions using sodium fluorescein dye: Implications for patients with dry eyes

ABSTRACT Purpose: To evaluate the lower labial minor salivary glands (MSGs) flow rate using fluorescein dye in healthy individuals and patients with Sjögren’s syndrome (SS) and Stevens–Johnson syndrome (SJS). Methods: Thirty consecutive patients with SS (N = 15; mean age 35.7 years) and SJS (N = 15; 57.7 years), and their age- and sex-matched healthy controls (N = 40; mean ocular surface disease index (OSDI) = 6.1) had ocular examination and whole lower labial mucosa evaluation after ophthalmic fluorescein strip application under cobalt blue light. Analyzed parameters include average labial distribution of functional MSGs, their secretory flow rate, and comparison between healthy and diseased groups. Results: The mean salivary flow rate from the lower labial MSGs of normal individuals showed decade-wise decline (2.7 ± 0.29 l/min, 2.6 ± 0.39 l/min, 2.3 ± 0.6 l/min, 1.9 ± 0.95 l/min) with similar trend for the number of secreting MSG openings (38.7, 37.2, 30, 22). The mean OSDI score was 45.3 in SJS and 28.2 in SS group. Thirty eyes in each SS and SJS group had mean Schirmer I value of 1.5 ± 2.2 mm and 5.1 ± 4.4 mm. The mean lower labial salivary flow rate in SS group was 0.5 ± 0.28 l/min, and 2.0 ± 0.95 l/min in SJS group. When compared to normal, SS patients had a significant reduction in the flow rate (p < .00001); however, it was not significant for the SJS group (p = .28). The mean number of secreting MSG openings was reduced in both the groups compared to normal (SJS, 20.5; p = .01 and SS, 12; p < .0001). There was a significant difference between SS and SJS groups in terms of flow rate (p < .00001) and number of MSG openings (p = .001). The MSG flow rate and Schirmer values did not show any correlation in SS or SJS patients. Conclusion: The fluorescein-assisted evaluation of the lower lip can be used as a quantitative method for measuring the labial salivary flow rate in SS and SJS patients.

UFMylation of RPL26 links translocation-associated quality control to endoplasmic reticulum protein homeostasis.

Protein biogenesis at the endoplasmic reticulum (ER) in eukaryotic cells is monitored by a protein quality control system named ER-associated protein degradation (ERAD). While there has been substantial progress in understanding how ERAD eliminates defective polypeptides generated from erroneous folding, how cells remove nascent chains stalled in the translocon during co-translational protein insertion into the ER is unclear. Here we show that ribosome stalling during protein translocation induces the attachment of UFM1, a ubiquitin-like modifier, to two conserved lysine residues near the COOH-terminus of the 60S ribosomal subunit RPL26 (uL24) at the ER. Strikingly, RPL26 UFMylation enables the degradation of stalled nascent chains, but unlike ERAD or previously established cytosolic ribosome-associated quality control (RQC), which uses proteasome to degrade their client proteins, ribosome UFMylation promotes the targeting of a translocation-arrested ER protein to lysosomes for degradation. RPL26 UFMylation is upregulated during erythroid differentiation to cope with increased secretory flow, and compromising UFMylation impairs protein secretion, and ultimately hemoglobin production. We propose that in metazoan, co-translational protein translocation into the ER is safeguarded by a UFMylation-dependent protein quality control mechanism, which when impaired causes anemia in mice and abnormal neuronal development in humans.

Role of Endoscopic Retrograde CholangioPancreatography (ERCP) and Intraductal Secretin Test (IDST) in the Diagnosis of Chronic Pancreatitis (CP)

Background: &#x0D; CP may be difficult to diagnose in the early stages when imaging may be normal. An IDST performed at ERCP may further evaluate for CP, with determination of pure pancreatic juice (PPJ) volume and bicarbonate concentration (BC). The optimal collection time for IDST is unknown. We report our experience with the IDST in 447 patients with suspected CP. &#x0D; Experimental Design: &#x0D; IDSTs performed from 2006-2018 were reviewed, with fluid collected at 5-min intervals for 20-60 minutes. Parameters evaluated were PPJ volume, Secretory Flow Rate (SFR), time of peak SFR, maximum BC and time to maximum BC. &#x0D; Results: &#x0D; Maximum BC was reached by 10-min in 59 patients (13.2%); 15-min: 207 patients (46.3%); 20 min: 340 patients (76.1%); 25-min: 384 patients (85.9%); 30-min: 421 patients (94.1%). Peak SFR was reached by 10-min in 92 patients (20.6%); 15-min: 177 patients (39.6%); 20-min: 240 patients (53.7%); 25-min: 284 patients (63.5%); 30-min: 323 patients (72.3%). Final diagnosis (normal vs. CP) for both SFR and BC was determined by 20-min (i.e. in CP pts, either the SFR or BC was low (SFR &lt;3ml/min, BC &lt;105mEq/L) and remained low throughout collection, or normal (&gt;3ml/min and &gt;105mEq/L) within the first 20-min. Further collection did not change the diagnosis. &#x0D; Conclusion: &#x0D; At IDST, a 20-minute collection period is necessary to categorize patients into normal or suspected CP groups. A study in control patients (no suspicion of CP) to validate these data is currently underway.

Autonomic reinnervation and functional regeneration in autologous transplanted submandibular glands in patients with severe keratoconjunctivitis sicca

Autologous submandibular gland (SMG) transplantation has been proved to ameliorate the discomforts in patients with severe keratoconjunctivitis sicca. The transplanted glands underwent a hypofunctional period and then restored secretion spontaneously. This study aims to investigate whether autonomic nerves reinnervate the grafts and contribute to the functional recovery, and further determine the origin of these nerves. Parts of the transplanted SMGs were collected from the epiphora patients, and a rabbit SMG transplantation model was established to fulfill the serial observation on the transplanted glands with time. The results showed that autonomic nerves distributed in the transplanted SMGs and parasympathetic ganglionic cells were observed in the stroma of the glands. Low-dense and unevenly distributed cholinergic axons, severe acinar atrophy and fibrosis were visible in the patients’ glands 4–6 months post-transplantation, whereas the cholinergic axon density and acinar area were increased with time. The acinar area or the secretory flow rate of the transplanted glands was statistically correlated with the cholinergic axon density in the rabbit model, respectively. Meanwhile, large cholinergic nerve trunks were found to locate in the temporal fascia lower to the gland, and sympathetic plexus concomitant with the arteries was observed both in the adjacent fascia and in the stroma of the glands. In summary, the transplanted SMGs are reinnervated by autonomic nerves and the cholinergic nerves play a role in the morphological and functional restoration of the glands. Moreover, these autonomic nerves might originate from the auriculotemporal nerve and the sympathetic plexus around the supplying arteries.

Management of duct obstruction in transplanted submandibular glands

BackgroundSubmandibular gland (SMG) transplantation is a successful treatment approach for patients with severe dry eye. However, duct obstruction can occur post-transplant. MethodsWe studied nineteen patients with duct obstruction of transplanted SMGs, including five interventional modalities: stone removal; secretory stimulation (to mimic "internal irrigation" with substantial secretory flow); irrigation; surgical opening of stenosis and orifice reconstruction; cephalic vein bypass and Wharton's duct reconstruction. ResultsA solitary stone was found and removed in one patient. Duct blockages like mucus plug were cleared by secretory stimulation in three patients, and by normal saline irrigation in two grafts. In the remaining 13 patients, irrigation failed and surgical opening was performed. Orifice reconstruction succeeded in six of the eight patients, whose stenosis was near the orifice. Wharton's duct reconstruction was successful in two of the five cases where stenosis was located in the middle segment of the duct. ConclusionTransplanted SMGs obstruct for various reasons. Stone, which is easy to diagnose and treat, should be excluded first. Non-organic blockage and stenosis were semblable in clinic. Therefore, subsequent steps should be a diagnostic/therapeutic trial of secretory stimulation, followed by irrigation; failure of these interventions suggests the diagnosis of duct stenosis, necessitating surgical recanalization.

Corrigendum.

CorrigendumCorrigendumPublished Online:04 May 2017https://doi.org/10.1152/ajpgi.GI-zh3-7316-corr.2017Original articleMoreSectionsPDF (23 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Volume 310, May 1, 2016Volume 73, May 1, 2016Pages G671–G681: Crothers JM Jr, Forte JG, Machen TE. Computer modeling of gastric parietal cell: significance of canalicular space, gland lumen, and variable canalicular [K+]. Am J Physiol Gastrointest Liver Physiol 310: G671–G681, 2016. First published February 4, 2016; doi: https://doi.org/10.1152/ajpgi.00431.2015.—Two excerpts below from construction of the parietal cell model (paragraph 6, sentence 1) and PPI inhibition and the electroneutral pump (paragraph 2, sentences 1–5) are here shown with corrected punctuation and corrected units of measure, respectively.The modeled basolateral membrane includes transport pathways to account for ion fluxes through the entire cell, to maintain homeostasis, and to allow the mimicking of transepithelial voltage clamping.The argument relied partly on underestimated luminal liquid flow of 15.9 μl·h−1·cm−2. With the frog's ECF osmolarity of ∼210 mosM (17), secretory [H+] could not be much above ∼100 mM, requiring secretory flow of ∼42 μl·h−1·cm−2 for their own reported H+ secretion of ∼4.2 μeq·h−1·cm−2. They overestimated luminal cross-sectional area as 0.035 cm2 per cm2 mucosa, requiring >10-μm diameter per lumen, given two glands per 100 μm (17), resulting in extremely low flow velocity of 0.000125 cm/s. Assuming that uninhibited H+/K+ exchange returns virtually all conductive apical K+ efflux to the cell, they treated back-diffusion of K+ from the bath as the only source of K+can in the stimulated state and used a formula, expressed in our terms as [K+]can = [K+]muc·e−vL/D, that yielded [K+]can of 64 mM when [K+]muc = 80 mM (with L = 0.03 cm and D = 1.7·10−5 cm2/s). Reasonable flow of 42 μl·h−1·cm−2 and luminal diameter of 3 μm, with 40,000 glands/cm2 (17), result in v ≈ 0.004 cm/s and, in their formula, [K+]can of 0.07 mM.This article has no references to display. Download PDF Previous Back to Top FiguresReferencesRelatedInformation Related ArticlesComputer modeling of gastric parietal cell: significance of canalicular space, gland lumen, and variable canalicular [K+] 01 May 2016American Journal of Physiology-Gastrointestinal and Liver Physiology More from this issue > Video Abstract Volume 312Issue 5May 2017Pages G535-G535 Copyright & PermissionsCopyright © 2017 the American Physiological Societyhttps://doi.org/10.1152/ajpgi.GI-zh3-7316-corr.2017PubMed28473419History Published online 4 May 2017 Published in print 1 May 2017 Metrics

Postprandial changes in secretory flow of pancreatic juice in the main pancreatic duct: evaluation with cine-dynamic MRCP with a spatially selective inversion-recovery (IR) pulse.

To evaluate the influence of oral ingestion on the secretory flow dynamics of physiological pancreatic juice within the main pancreatic duct in healthy subjects by using cine-dynamic MRCP with spatially-selective inversion-recovery (IR) pulse non-invasively. Thirty-eight healthy subjects were investigated. MRCP with spatially-selective IR pulse was repeated every 15s for 5min to acquire a total of 20 images (cine-dynamic MRCP). A set of 20 MRCP images was repeatedly obtained before and after liquid oral ingestion every 7min (including 2-min interval) for 40min (a total of seven sets). Secretion grade of pancreatic juice on cine-dynamic MRCP was compared before and after oral ingestion using the nonparametric Wilcoxon signed-rank test. Median secretion grades of pancreatic juice at 5min (score = 2.15), 12min (score = 1.95) and 19min (score = 2.05) after ingestion were significantly higher than that before ingestion (score = 1.40) (P = 0.004, P = 0.032, P = 0.045, respectively). Secretion grade of pancreatic juice showed a maximum peak of 2.15 at 5min after ingestion. Thereafter, the secretion grade of pancreatic juice tended to gradually decline. Non-invasive cine-dynamic MRCP using spatially-selective IR pulse showed potential for evaluating postprandial changes in the secretory flow dynamics of pancreatic juice as a physiological reaction. • Secretion grade of pancreatic juice at cine-dynamic MRCP after ingestion was evaluated. • Secretion grade was significantly increased within 19min after liquid meal ingestion. • Secretion grade showed maximum peak of 2.15 at 5min after ingestion. • Postprandial changes in pancreatic juice flow can be assessed by cine-dynamic MRCP.

Age-related change of the secretory flow of pancreatic juice in the main pancreatic duct: evaluation with cine-dynamic MRCP using spatially selective inversion recovery pulse.

The purpose of this study is to evaluate age-related changes in the secretory flow of pancreatic juice in the main pancreatic duct noninvasively by means of nonpharmacologic cine-dynamic MRCP using spatially selective inversion recovery (IR) pulse. Fifty-three subjects without a history of pancreatic disease were included. Four-second breath-hold MRCP using spatially selective IR pulse was performed every 15 seconds during 5 minutes (acquiring a total of 20 images) in cine-dynamic fashion. The secretion grade was classified into five grades by the distance of pancreatic juice inflow within the tagged area. The mean secretion grade and the frequency of secretion in cine-dynamic MRCP were compared among three age-range groups (group 1, < 40 years; group 2, 40-70 years; and group 3, > 70 years). Statistical analysis was performed using Spearman rank correlation coefficient and Kruskal-Wallis and Mann-Whitney U tests. The secretion grade and the frequency of secretion were significantly reduced with aging (r = -0.77, p < 0.001; and r = -0.74, p < 0.001, respectively). The mean secretion grade and the frequency of secretion were significantly lower in group 3 than in group 2 (mean grade, 0.36 vs 1.48, p = 0.001; and 4.8 vs 11.9 times, p = 0.001) and were lower in group 2 than in group 1 (mean grade, 1.48 vs 2.48, p < 0.001; and 11.9 vs 16.2 times, p = 0.011). Cine-dynamic MRCP using spatially selective IR pulse was able to show the age-related decrease of the secretory flow of pancreatic juice in the main pancreatic duct visually and noninvasively.

Rare Cause of Recurrent Pancreatitis

Introduction: Congenital anomalies and variants of pancreas are one of the uncommon causes for pancreatitis. Pancreatic divisum is one of them, with an incidence rate of 3%. Case Description: A 32-year-old female was admitted to our institution for abdominal pain, nausea, and vomiting for 3 days. She denied fever, chills, or diarrhea. The patient was admitted twice in the past for acute pancreatitis which was thought to be secondary to gallstones and patient had cholecystectomy. She drank alcohol occasionally and had a history of 10 pack-years of smoking. Examination revealed normal vital signs, epigastric tenderness to palpation on abdominal exam with no guarding or rigidity. Laboratory values revealed lipase of 2,796 and amylase of 292, the rest unremarkable. Patient was given bowel rest and was given intravenous fluids with no relief. CT scan abdomen was unremarkable. Secretin-enhanced endoscopic ultrasound study was done, which was positive for pancreatic divisum. Pancreatic stent was placed, which relieved her symptoms and patient has been doing fine in last 2 months of follow-up. Discussion: There are various types of congenital anomalies of pancreas—pancreatic divisum being one of them—caused by failure of fusion of ventral and dorsal duct system. The body, tail, and head of the pancreas (dorsal pancreas) drain through the Santorini's duct into the minor papilla, while another part of head (ventral pancreas) drains through Wirsung's duct into major papilla. Most patients are asymptomatic but relative obstruction to pancreatic exocrine secretory flow through duct of Santorini and minor papilla can cause pancreatitis in few patients. Endoscopic retrograde cholangiopancreatography (ERCP) is the most definitive and reliable diagnostic test for pancreatic divisum. Minor papilla orifice is not evident in one third of cases in which case secretin can be administered intravenously. Endoscopic stenting and sphincterotomy of minor papilla can be an effective therapy.To summarize, our case highlights the the need for maintaining a high index of suspicion for congenital anomalies in patients presenting with recurrent pancreatitis.Figure: ERCP showing pancreatic divisum.

Anatomical and Histological Organization of the Testes of the Inseminating CatfishTrachelyopterus striatulus(Steindachner, 1877) (Siluriformes: Auchenipteridae)

The testicular morphology, spermatogenesis and occurrence of sperm in the ovarian lumen of Trachelyopterus striatulus were studied using anatomical, histological and biometric techniques. A total of 50 catfish (T. striatulus) were captured, measuring 14.9 ± 2.5 cm of standard length, body weight was 81.2 ± 34.5 g and their testes weighed 16.9 ± 6.1 g. The testes of T. striatulus are paired organs, showing two distinct regions: cranial, which shows a compact medial part and with fringes ventrally, and caudal region, which is formed of the seminal vesicle with fringes laterally and two saculiform expansions. The testes presented a length of 35.2 ± 6.9 mm, and the fringes showed a cranial length of 12.1 ± 3.8 mm and caudal length of 6.4 ± 2.6 mm. Histologically, the cranial fringes are spermatogenic and showed cells with significantly different nuclear diameters, ranging from 8.2 ± 1.5 μm (primary spermatogonia) to 1.88 ± 0.3 μm (spermatid). The seminal vesicles and saculiform expansions showed tubules with a simple prismatic secretory epithelium containing spermatozoa and secretion into the lumen. The caudal fringes are exclusively for secretory flow, consisting of tubules with a simple cuboidal epithelium. The common spermatic duct showed a simple cuboidal epithelium and contained spermatozoa with secretion into the lumen. The secretion of the caudal region is acidophilic, with neutral glycoproteins and sialomucin. T. striatulus ovaries showed free spermatozoa or were organized in spermatozeugmata into the ovarian lumen and between the ovuligers lamellae.

Effect of Corvitin on Secretory Processes and Blood Flow in the Rat Gastric Mucosa

Effect of Corvitin on Secretory Processes and Blood Flow in the Rat Gastric Mucosa

Chirurgia dei tessuti molli: gestione delle lesioni a livello dei dotti salivari

ObjectivesTo review the surgical management of salivary duct lesions, the authors describe the treatment of three patients, one with a traumatic pseudofibroma of Stensen's duct, the second with a mucocele involving the sublingual gland, and the third with sialolithiasis of Wharton's duct. Materials and methodsUsing duct cannulation, sialodochoplasty, and lesion marsupialization, the oral surgeon could treat the most part of oral diseases close to salivary ducts and preserve their integrity. By this way could promote proper healing, eliminate risk of saliva extravasation and complications due to obstructed secretory flow. Results and conclusionsWith careful surgical planning and careful technique, salivary duct lesions can easily be treated without complications involving slight structures close to them.

The Secretory Flow of Pancreatic Juice in the Main Pancreatic Duct: Visualization by Means of MRCP with Spatially Selective Inversion-Recovery Pulse

To assess the feasibility of visualizing noninvasively the physiologic flow of pancreatic juice by using serial magnetic resonance cholangiopancreatography (MRCP) with a spatially selective inversion-recovery (IR) pulse in volunteers and patients with pancreatic disease. The study was approved by the institutional review board, and informed consent was obtained. Twelve healthy volunteers and three patients with acute pancreatitis were included. MRCP with a spatially selective IR pulse was repeatedly performed every 15 seconds during a total of 10 minutes (total of 40 images). MRCP images were evaluated for the presence, frequency, and magnitude of pancreatic juice inflow within the tagged area. The two groups were compared by using the Mann-Whitney test. Pancreatic juice inflow was observed in all healthy volunteers and in two of three patients with acute pancreatitis. The pancreatic fluid inflow was observed 25-37 times (median, 32 times; mean, 31.4 times; range, 25-37 times) in a series of 40 images in 12 healthy volunteers, while it was seen 0-11 times (median, 2 times; mean, 4.3 times; range, 0-11 times) in a series of 40 images in the three patients with acute pancreatitis (P = .009). No regularity in the timing of the pancreatic fluid inflow was noted. The distance that the pancreatic fluid moved in the pancreatic duct within the tagged area was significantly longer in healthy volunteers (median grade, 2.46; mean grade, 2.41; range, 1.6-3.3) than in patients with acute pancreatitis (median grade, 0.05; mean grade, 0.13; range, 0-0.35) (P = .009). The physiologic flow of the pancreatic juice can be visualized noninvasively with serial MRCP by using a spatially selective IR pulse.

Water cotransport in pigmented epithelial cells

Water cotransport in pigmented epithelial cells

Intraductal Secretin Stimulation Test: What Is the Proper Collection Time?

Pancreatic function tests are helpful methods to establish or exclude a diagnosis of chronic pancreatitis (CP). Many studies confirm the clinical utility of the intraductal secretin test (IDST), and that the most discriminatory parameters used are secretory flow rate (SFR) and bicarbonate concentration (BC)∗. Forty-five minutes (min) IDST collection time was recommended by some investigators. A shorter collection time has been proposed to increase the practicality of the IDST, but the precise time has been not well defined. The aim of our study is to establish the IDST proper collection time. Method: The results of 68 IDSTs done in our center were evaluated. Pure pancreatic juice (PPJ) was collected after an IV injection of 16 μg of synthetic secretin (SecreFlo, ChiRhoClin, Inc, Burtonsville). The first 5-min collection was discarded and the PPJ was then collected at 5 minutes intervals up to 45 min. A triple lumen manometry catheter was used to collect the PPJ. The parameters evaluated were the peak SFR, time of peak SFR, max BC (measured by back titration), and time of max BC. Normal SFR was defined as ≥3 ml/min and normal BC was defined as ≥105 mEq/L∗. Results: Max BC was reached by the collection time of 6-10 min in 11 patients (pts) (16%), by 11-15 min in 43 pts (63%), by 16-20 min in 60 pts (88%), by 21-25 min in 65 pts (95%) and by 26-30 min in all pts (100%). Peak SFR was reached by the collection time 6-10 min in 24 pts (36%), by 11-15 min in 37 pts (55%), by 16-20 min in 52 pts (77%), by 21-25 min in 57 pts (84%) and by 26-30 min in all pts (100%). However, all pts reached their final diagnostic classification (normal versus CP) for both the SFR and BC by 20 min collection period [i.e. either the SFR was low (<3 ml/min) from the beginning and remained low throughout the collection time, or normal (≥3 ml/min) within the first 20 min collection time; the same was seen for BC]. Further collection time did not change their final diagnosis. Based on BC criteria, 15 pts had CP (22%). Based on SFR criteria, 31 pts had CP (45%), by either criteria 45% had CP. Summary: The final clinical diagnosis of CP was established or excluded by the first 20 min collection period (for both SFR and BC) in all pts. Conclusions: The first 20-minute collection period during IDST was sufficient time for diagnosing or excluding CP in all pts in this series. This data confirms prior studies showing adequacy of 15-20 min IDST collection time.∗∗Sivak M. Gastroenterologic Endoscopy. 2nd W.B. Saunders Company, 2000:1116-1118.

Iatrogenic Jejunal Perforation during Duodenal Stricture Dilatation Secondary to Groove Pancreatitis

A 35 y/o female with a history of alcoholic chronic pancreatitis was transferred for open surgical repair of an iatrogenic, proximal jejunal perforation during endoscopic balloon dilatation of a presumed benign duodenal stricture. Three months previously, she had undergone gastrojejunostomy secondary to duodenal obstructive symptoms. The stricture was located in the duodenal c-sweep and perforation occurred just distal to the stricture in the afferent jejunal limb while attempting retrograde dilation. Following primary closure, the patient underwent an MRI to evaluate the stricture and a focal 1.5 cm fluid collection was found in the pancreatic head adjacent to the second portion of the duodenum with associated pancreatic head enlargement. EUS revealed mass-like enlargement of the pancreatic head with a focal 1.5 cm fluid collection and chronic inflammatory changes in the body and tail. EUS-FNA of the fluid collection and surrounding pancreatic parenchyma revealed cell block portions featuring spindle cell proliferation with nuclear atypia, marked cellularity and high mitotic activity. Based on subsequent immunohistochemistry, the pancreatic head lesion appeared to be a malignant spindle cell neoplasm with smooth muscle differentiation. Uneventful pancreaticoduodenectomy was performed three months following her perforation. Pathology revealed fibrosis of the adjacent pancreas, Brunner's gland hyperplasia, and bundles of smooth muscle within the duodenum that were interspersed with dilated ducts containing inspissated secretions. All findings were consistent with a diagnosis of paraduodenal pancreatitis, or groove pancreatitis. Groove pancreatitis is a rare form of segmental chronic pancreatitis that involves the anatomic space between the head of the pancreas, the duodenum, and the common bile duct. It has been associated with alcoholic chronic pancreatitis and its etiology is thought secondary to disruption of normal pancreatic secretory flow via the minor papilla. The differential diagnosis of patients with external duodenal compression, chronic pancreatitis, and pancreatic head fullness should include groove pancreatitis. This is the first reported case of iatrogenic perforation during endoscopic treatment of a duodenal stricture secondary to groove pancreatitis.

Vacuolar H+-ATPase Activity Is Required for Endocytic and Secretory Trafficking inArabidopsis

In eukaryotic cells, compartments of the highly dynamic endomembrane system are acidified to varying degrees by the activity of vacuolar H(+)-ATPases (V-ATPases). In the Arabidopsis thaliana genome, most V-ATPase subunits are encoded by small gene families, thus offering potential for a multitude of enzyme complexes with different kinetic properties and localizations. We have determined the subcellular localization of the three Arabidopsis isoforms of the membrane-integral V-ATPase subunit VHA-a. Colocalization experiments as well as immunogold labeling showed that VHA-a1 is preferentially found in the trans-Golgi network (TGN), the main sorting compartment of the secretory pathway. Uptake experiments with the endocytic tracer FM4-64 revealed rapid colocalization with VHA-a1, indicating that the TGN may act as an early endosomal compartment. Concanamycin A, a specific V-ATPase inhibitor, blocks the endocytic transport of FM4-64 to the tonoplast, causes the accumulation of FM4-64 together with newly synthesized plasma membrane proteins, and interferes with the formation of brefeldin A compartments. Furthermore, nascent cell plates are rapidly stained by FM4-64, indicating that endocytosed material is redirected into the secretory flow after reaching the TGN. Together, our results suggest the convergence of the early endocytic and secretory trafficking pathways in the TGN.

Early Secretory Pathway Gene TRS85 is Required for Selective Macroautophagy of Peroxisomes in Yarrowia lipolytica

Yarrowia lipolytica was recently introduced as a new model organism to study peroxisome degradation in yeasts. Transfer of Y. lipolytica cells from oleate/ethylamine to glucose/ammonium chloride medium leads to selective macroautophagy of peroxisomes. To decipher the molecular mechanisms of macropexophagy we made use of Y. lipolytica tagged mutants affected in the inactivation of peroxisomal enzymes under pexophagy conditions, Ain16 and Ain19. Both strains appeared to be disrupted at two different sites of the same gene, YlTRS85, the ortholog of Saccharomyces cerevisiae TRS85 that encodes 85 kDa subunit of transport protein particle (TRAPP). Y. lipolytica trs85 mutants had multiple defects of protein transport to external medium, cell wall and vacuoles, indicating that YlTrs85 is indeed the ScTrs85 functional homologue, required early in the classical secretory pathway. Interestingly, peroxisomes were not able to reach vacuoles under pexophagy conditions in both Ain16 and Ain19 strains. Therefore, the essential role of the early secretory flow in selective macroautophagy of peroxisomes is suggested.