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We evaluated a protocolized endoscopic necrosectomy approach with a lumen-apposing metal stent (LAMS) in patients with large symptomatic walled-off pancreatic necrosis (WON) comprising significant necrotic content, with or without infection.Randomized trials have shown similar efficacy of endoscopic treatment compared to surgery for infected WON.We conducted a regulatory, prospective, multicenter single-arm clinical trial examining the efficacy and safety of endoscopic ultrasound (EUS)-guided LAMS with protocolized necrosectomy to treat symptomatic WON ≥ 6 cm in diameter with 30% solid necrosis. After LAMS placement, protocolized WON assessment was conducted and endoscopic necrosectomy was performed for insufficient WON size reduction and persistent symptoms. Patients with radiographic WON resolution to ≤ 3 cm and/or 60-day LAMS indwell had LAMS removal, then 6-month follow-up. Primary endpoints were probability of radiographic resolution by 60 days and procedure-related serious adverse events (SAEs).Forty consecutive patients were enrolled September 2018 - March 2020, of whom 27 (67.5%) were inpatients and 19 (47.5%) had clinical evidence of infection at their index procedure. Mean WON size was 15.0 ± 5.6 cm with mean 53.2% ± 16.7% solid necrosis. Radiographic WON resolution was seen in 97.5% (95% CI, 86.8%, 99.9%) by 60 days, without recurrence in 34 patients with 6-month follow-up data. Mean time to radiographic WON resolution was 34.1 ± 16.8 days. SAEs occurred in 3 patients (7.5%), including sepsis, vancomycin-resistant enterococcal bacteremia and shock, and upper gastrointestinal bleeding. There were no procedure-related deaths.EUS-guided drainage with protocolized endoscopic necrosectomy to treat large symptomatic or infected walled-off necrotic pancreatic collections was highly effective and safe. Clinicaltrials.gov no: NCT03525808.

BACKGROUND & AIMS: Benign biliary strictures (BBS) are complications of chronic pancreatitis (CP). Endotherapy using multiple plastic stents (MPS) or a fully covered self-expanding metal stent (FCSEMS) are acceptable treatment options for biliary obstructive symptoms in these patients. METHODS: Patients with symptomatic CP-associated BBS enrolled in a multicenter randomized noninferiority trial comparing 12-month treatment with MPS vs FCSEMS. Primary outcome was stricture resolution status at 24 months, defined as absence of restenting and 24-month serum alkaline phosphatase not exceeding twice the level at stenting completion. Secondary outcomes included crossover rate, numbers of endoscopic retrograde cholangiopancreatography (ERCPs) and stents, and stent- or procedure-related serious adverse events. RESULTS: Eighty-four patients were randomized to MPS and 80 to FCSEMS. Baseline technical success was 97.6% for MPS and 98.6% for FCSEMS. Eleven patients crossed over from MPS to FCSEMS, and 10 from FCSEMS to MPS. For MPS vs FCSEMS, respectively, stricture resolution status at 24 months was 77.1% (54/70) vs 75.8% (47/62) (P = .008 for noninferiority intention-to-treat analysis), mean number of ERCPs was 3.9 ± 1.3 vs 2.6 ± 1.3 (P < .001, intention-to-treat), and mean number of stents placed was 7.0 ± 4.4 vs 1.3 ± .6 (P < .001, as-treated). Serious adverse events occurred in 16 (19.0%) MPS and 19 (23.8%) FCSEMS patients (P = .568), including cholangitis/fever/jaundice (9 vs 7 patients respectively), abdominal pain (5 vs 5), cholecystitis (1 vs 3) and post-ERCP pancreatitis (0 vs 2). No stent- or procedure-related deaths occurred. CONCLUSIONS: Endotherapy of CP-associated BBS has similar efficacy and safety for 12-month treatment using MPS compared with a single FCSEMS, with FCSEMS requiring fewer ERCPs over 2 years. (ClinicalTrials.gov, Number: NCT01543256.). ispartof: GASTROENTEROLOGY vol:161 issue:1 pages:185-195 ispartof: location:United States status: published

Background and study aims Lumen-apposing metal stents (LAMS) are increasingly used for drainage of walled-off pancreatic necrosis (WON). Recent studies suggested greater adverse event (AE) rates with LAMS for WON. We conducted a systematic review and meta-analysis to compare the safety and efficacy of LAMS with double-pigtail plastic stents (DPPS) for endoscopic drainage of WON. The primary aim was to evaluate stent-related AEs. Methods In October 2019, we searched the Ovid (Embase, MEDLINE, Cochrane) and Scopus databases for studies assessing a specific LAMS or DPPS for WON drainage conducted under EUS guidance. Safety outcomes were AE rates of bleeding, stent migration, perforation, and stent occlusion. Efficacy outcomes were WON resolution and number of procedures needed to achieve resolution. A subanalysis including non-EUS-guided cases was performed. Results Thirty studies including one randomized controlled trial (total 1,524 patients) were analyzed. LAMS were associated with similar bleeding (2.5 % vs. 4.6 %, P = 0.39) and perforation risk (0.5 % vs. 1.1 %, P = 0.35) compared to DPPS. WON resolution (87.4 % vs. 87.5 %, P = 0.99), number of procedures to achieve resolution (2.09 vs. 1.88, P = 0.72), stent migration (5.9 % vs. 6.8 %, P = 0.79), and stent occlusion (3.8 % vs. 5.2 %, P = 0.78) were similar for both groups. Inclusion of non-EUS-guided cases led to significantly higher DPPS bleeding and perforation rates. Conclusions LAMS and DPPS were associated with similar rates of AEs and WON resolution when limiting analysis to EUS-guided cases. Higher bleeding rates were seen in historical studies of DPPS without EUS guidance. Additional high-quality studies of WON treatment using consistent outcome definitions are needed.

Background Peroral cholangioscopy (POCS) can be useful for difficult bile duct stone clearance. Large prospective multinational data on POCS-guided lithotripsy for clearing difficult bile duct stones in a single session of endoscopic retrograde cholangiopancreatography (ERCP) are missing. Methods Patients with difficult bile duct stones (defined as one or more of: largest stone diameter ≥ 15 mm, failed prior attempt at stone clearance, impacted, multiple, hepatic duct location, or located above a stricture) were enrolled at 17 centers in 10 countries. The principal endpoint was stone clearance in a single ERCP procedure using POCS. Results 156 patients underwent 174 sessions of POCS-guided electrohydraulic or laser lithotripsy. Stone clearance had failed in a previous ERCP using traditional techniques in 124/156 patients (80 %), while 32 /156 patients (21 %) were referred directly to POCS-guided therapy based on preprocedural assessment of the difficulty of stone clearance. In 101/156 patients (65 %), there were impacted stones. POCS-guided stone clearance was achieved in a single POCS procedure in 125 /156 patients (80 %, 95 % confidence interval [CI] 73 % – 86 %), and was significantly more likely for stones ≤ 30 mm compared with > 30 mm (odds ratio 7.9, 95 %CI 2.4 – 26.2; P = 0.002). Serious adverse events occurred in 3/156 patients (1.9 %, 95 %CI 0.4 % – 5.5 %), and included pancreatitis, perforation due to laser lithotripsy, and cholangitis (n = 1 each), all resolved within 1 week. Conclusion POCS-guided lithotripsy is highly effective for clearance of difficult bile duct stones in a single procedure and successfully salvages most prior treatment failures. It may also be considered first-line therapy for patients with difficult choledocholithiasis to avoid serial procedures.

Background and Aims: Minimally invasive treatments of anastomotic benign biliary stricture (BBS) after orthotopic liver transplantation (OLT) include endoscopic placement of multiple plastic stents or fully covered self-expandable metal stents (FCSEMSs). No multiyear efficacy data are available on FCSEMS treatment after OLT. Methods: We prospectively studied long-term efficacy and safety of FCSEMS treatment in adults aged ≥18 years with past OLT, cholangiographically confirmed BBS, and an indication for ERCP with stent placement. Stent removal was planned after 4 to 6 months, with subsequent follow-up until 5 years or stricture recurrence. Long-term outcomes were freedom from stricture recurrence, freedom from recurrent stent placement, and stent-related serious adverse events (SAEs). Results: In 41 patients, long-term follow-up began after FCSEMS removal (n = 33) or observation of complete distal migration (CDM) (n = 8). On an intention-to-treat basis, the 5-year probability of remaining stent-free after FCSEMS removal or observation of CDM was 48.9% (95% confidence interval [CI], 33.2%-64.7%) among all patients and 60.9% (95% CI, 43.6%-78.2%) among 31 patients with over 4 months of FCSEMS indwell time. In 28 patients with stricture resolution at FCSEMS removal or observed CDM (median, 5.0 months indwell time), the 5-year probability of no stricture recurrence was 72.6% (95% CI, 55.3%-90%). Sixteen patients (39%) had at least 1 related SAE, most commonly cholangitis (n = 10). Conclusions: By 5 years after temporary FCSEMS treatment of post-OLT BBS, approximately half of all patients remained stent-free on an intention-to-treat basis. Stent-related SAEs (especially cholangitis) were common. FCSEMS placement is a viable long-term treatment option for patients with post-OLT BBS. (Clinical trial registration number: NCT01014390.), SCOPUS: ar.j, info:eu-repo/semantics/published

Background Peroral cholangioscopy (POCS) of indeterminate biliary strictures aims to achieve a diagnosis through visual examination and/or by obtaining targeted biopsies under direct visualization. In this large, prospective, multinational, real-life experience of POCS-guided evaluation of indeterminate biliary strictures, we evaluated the performance of POCS in this difficult-to-manage patient population. Methods This prospective registry enrolled patients, with indeterminate biliary strictures across 20 centers in Asia, the Middle East, and Africa. The primary end points were the ability to visualize the lesion, obtain histological sampling when intended, and an assessment of the diagnostic accuracy of POCS for malignant strictures. Patients were followed for 6 months after POCS or until a definitive malignant diagnosis was made, whichever occurred first. Results 289 patients underwent 290 POCS procedures with intent to biopsy in 182 cases. The stricture/filling defect was successfully visualized in 286/290 (98.6 %), providing a visual diagnostic impression in 253/290 (87.2 %) and obtaining adequate biopsies in 169/182 (92.9 %). Procedure-related adverse events occurred in 5/289 patients (1.7 %). POCS influenced patient management principally by elucidating filling defects or the causes of bile duct stricture or dilation. The visual impression of malignancy showed 86.7 % sensitivity, 71.2 % specificity, 65.8 % positive and 89.4 % negative predictive value, and 77.2 % overall accuracy compared with final diagnosis. Histological POCS-guided samples showed 75.3 % sensitivity, 100 % specificity, 100 % positive and 77.1 % negative predictive value, and 86.5 % overall accuracy. Conclusion In this large, real-life, prospective series, POCS was demonstrated to be an effective and safe intervention guiding the management of patients with indeterminate biliary strictures.

Background and Aims: Temporary single, fully covered self-expanding metal stent (FCSEMS) placement for benign biliary strictures (BBSs) associated with chronic pancreatitis (CP) may require fewer interventions than endotherapy with multiple plastic stents and may carry less morbidity than biliary diversion surgery. This study aimed to assess long-term outcomes in CP-associated BBSs after FCSEMS placement and removal. Methods: In this open-label, multinational, prospective study, subjects with CP and a BBS treated with FCSEMS placement with scheduled removal at 10 to 12 months were followed for 5 years after FCSEMS indwell. Kaplan-Meier analyses assessed BBS resolution and cumulative probability of freedom from recurrent stent placement to 5 years after FCSEMS indwell. Results: One hundred eighteen patients were eligible for FCSEMS removal. At a median of 58 months (interquartile range, 44-64) post-FCSEMS indwell, the probability of remaining stent-free was 61.6% (95% confidence interval [CI], 52.5%-70.7%). In 94 patients whose BBSs resolved at the end of FCSEMS indwell, the probability of remaining stent-free 5 years later was 77.4% (95% CI, 68.4%-86.4%). Serious stent-related adverse events occurred in 27 of 118 patients (22.9%); all resolved with medical therapy or repeated endoscopy. Multivariate analysis identified severe CP (hazard ratio, 2.4; 95% CI, 1.0-5.6; P = .046) and longer stricture length (hazard ratio, 1.2; 95% CI, 1.0-1.4; P = .022) as predictors of stricture recurrence. Conclusion: In patients with symptomatic BBSs secondary to CP, 5 years after placement of a single FCSEMS intended for 10 to 12 months indwell, more than 60% remained asymptomatic and stent-free with an acceptable safety profile. Temporary placement of a single FCSEMS may be considered as first-line treatment for patients with CP and BBSs. (Clinical trial registration number: NCT 01014390.), info:eu-repo/semantics/published

Multidrug-resistant infectious outbreaks associated with duodenoscope reuse have been documented internationally. A single-use endoscope could eliminate exogenous patient-to-patient infection associated with ERCP.We conducted a comparative bench simulation study of a new single-use and 3 models of reusable duodenoscopes on a synthetic anatomic bench model. Four ERCP tasks were performed: guidewire locking (single-use and 1 reusable duodenoscope only), plastic stent placement and removal, metal stent placement and removal, and basket sweeping. The study schedule included block randomization by 4 duodenoscopes, 4 tasks, and 2 anatomic model ERCP stations. Ability to complete tasks, task completion times, and subjective ratings of overall performance, navigation/pushability, tip control, and image quality on a scale of 1 (worst) to 10 (best) were compared among duodenoscopes.All 4 ERCP tasks (total 14 subtasks) were completed by 6 expert endoscopists using all 4 duodenoscopes, with similar task completion times (median, 1.5-8.0 minutes per task) and overall performance ratings by task (median, 8.0-10.0). Navigation/pushability ratings were lower for the single-use duodenoscope than for the 3 reusable duodenoscopes (median, 8.0, 10.0, 9.0, and 9.0, respectively; P .01). Tip control ratings were similar among all the duodenoscopes (median, 9.0-10.0; P = .77). Image quality ratings were lower for 1 reusable duodenoscope compared with the single-use and other 2 reusable duodenoscopes (median, 8.0, 9.0, 9.0, and 9.0, respectively; P .01).A new single-use duodenoscope was used to simulate 4 ERCP tasks in an anatomic model, with performance ratings and completion times comparable with 3 models of reusable duodenoscopes.

Background & Aims Disposable, single-use duodenoscopes might reduce outbreaks of infections associated with endoscope reuse. We tested the feasibility, preliminary safety, and performance of a new single-use duodenoscope in patients undergoing endoscopic retrograde cholangiopancreatography (ERCP). Methods We conducted a case-series study of the outcomes of ERCP with a single-use duodenoscope from April through May 2019 at 6 academic medical centers. We screened consecutive patients (18 years and older) without alterations in pancreaticobiliary anatomy and enrolled 73 patients into the study. Seven expert endoscopists performed roll-in maneuvers (duodenoscope navigation and visualization of duodenal papilla only) in 13 patients and then ERCPs in the 60 other patients. Outcomes analyzed included completion of ERCP for the intended clinical indication, crossover from a single-use duodenoscope to a reusable duodenoscope, endoscopist performance ratings of the device, and serious adverse events (assessed at 72 hours and 7 days). Results Thirteen (100%) roll-in maneuver cases were completed using the single-use duodenoscope. ERCPs were of American Society for Gastrointestinal Endoscopy procedural complexity grade 1 (least complex; 7 patients [11.7%]), grade 2 (26 patients [43.3%]), grade 3 (26 patients [43.3%]), and grade 4 (most complex; 1 patient [1.7%]). Fifty-eight ERCPs (96.7%) were completed using the single-use duodenoscope only and 2 ERCPs (3.3%) were completed using the single-use duodenoscope followed by crossover to a reusable duodenoscope. Median overall satisfaction was 9 out of 10. Three patients developed post-ERCP pancreatitis, 1 patient had post-sphincterotomy bleeding, and 1 patient had worsening of a preexisting infection and required rehospitalization. Conclusions In a case-series study, we found that expert endoscopists can complete ERCPs of a wide range of complexity using a single-use duodenoscope for nearly all cases. This alternative might decrease ERCP-related risk of infection. Clinicaltrials.gov no: NCT03701958 .

Background and Aims: Preoperative biliary drainage with self-expanding metal stents (SEMSs) brings liver function within an acceptable range in preparation for neoadjuvant therapy (NATx) and provides relief of obstructive symptoms in patients with pancreatic cancer. We compared fully-covered SEMSs (FCSEMSs) and uncovered SEMSs (UCSEMSs) for sustained biliary drainage before and during NATx. Methods: Patients with pancreatic cancer and planned NATx who need treatment of jaundice and/or cholestasis before pancreaticoduodenectomy were randomized to FCSEMSs versus UCSEMSs. The primary endpoint was sustained biliary drainage, defined as the absence of reinterventions for biliary obstructive symptoms, and was assessed from SEMS placement until curative intent surgery or at 1 year. Results: The intention-to-treat population included 119 patients (59 FCSEMSs, 60 UCSEMSs). Sustained biliary drainage was equally successful with FCSEMSs and UCSEMSs (72.2% vs 72.9%, noninferiority P =.01). Reasons for FCSEMS and UCSEMS failure differed significantly between the groups and included tumor ingrowth in 0% versus 16.7% (P, SCOPUS: ar.j, info:eu-repo/semantics/published

This article has an accompanying continuing medical education activity on page e15. Learning Objective: upon completion of this activity, participants should be able to discuss the indications to use self-expandable metal stents (SEMS) for management of benign biliary strictures, identify patients at high-risk and low-risk for migration of these stents after placement, and understand the risks and benefits of fully-covered, self-expandable metal stents (FCSEMS) versus plastic stents for management of chronic pancreatitis. BACKGROUND & AIMS: Fully covered self-expanding metal stents (FCSEMS) are gaining acceptance for the treatment of benign biliary strictures. We performed a large prospective multinational study to study the ability to remove these stents after extended indwell and the frequency and durability of stricture resolution. METHODS: In a nonrandomized study at 13 centers in 11 countries, 187 patients with benign biliary strictures received FCSEMS. Removal was scheduled at 10-12 months for patients with chronic pancreatitis or cholecystectomy and at 4-6 months for patients who received liver transplants. The primary outcome measure was removal success, defined as either scheduled endoscopic removal of the stent with no removal-related serious adverse events or spontaneous stent passage without the need for immediate restenting. RESULTS: Endoscopic removal of FCSEMS was not performed for 10 patients because of death (from unrelated causes), withdrawal of consent, or switch to palliative treatment. For the remaining 177 patients, removal success was accomplished in 74.6% (95% confidence interval [CI], 67.5%-80.8%). Removal success was more frequent in the chronic pancreatitis group (80.5%) than in the liver transplantation (63.4%) or cholecystectomy (61.1%) groups (P = .017). FCSEMS were removed by endoscopy from all patients in whom this procedure was attempted. Stricture resolution without restenting upon FCSEMS removal occurred in 76.3% of patients (95% CI, 69.3%-82.3%). The rate of resolution was lower in patients with FCSEMS migration (odds ratio, 0.22; 95% CI, 0.11-0.46). Over a median follow-up period of 20.3 months (interquartile range, 12.9-24.3 mo), the rate of stricture recurrence was 14.8% (95% CI, 8.2%-20.9%). Stent-or removal-related serious adverse events, most often cholangitis, occurred in 27.3% of patients. There was no stent-or removal-related mortality. CONCLUSIONS: In a large prospective multinational study, removal success of FCSEMS after extended indwell and stricture resolution were achieved for approximately 75% of patients.

Background The feasibility of single-operator cholangioscopy (SOC) for biliary diagnostic and therapeutic procedures was previously reported. Objective To confirm the utility of SOC in more widespread clinical use. Design Prospective clinical cohort study. Setting Fifteen endoscopy referral centers in the United States and Europe. Patients Two hundred ninety-seven patients requiring evaluation of bile duct disease or biliary stone therapy. Interventions SOC examination and, as indicated, SOC-directed stone therapy or forceps biopsy. Main Outcome Measurements Procedural success defined as ability to (1) visualize target lesions and, if indicated, collect biopsy specimens adequate for histological evaluation or (2) visualize biliary stones and initiate fragmentation and removal. Results The overall procedure success rate was 89% (95% CI, 84%-92%). Adequate tissue for histological examination was secured in 88% of 140 patients who underwent biopsy. Overall sensitivity in diagnosing malignancy was 78% for SOC visual impression and 49% for SOC-directed biopsy. Sensitivity was higher (84% and 66%, respectively) for intrinsic bile duct malignancies. Diagnostic SOC procedures altered clinical management in 64% of patients. Procedure success was achieved in 92% of 66 patients with stones and complete stone clearance during the study SOC session in 71%. The incidence of serious procedure-related adverse events was 7.5% for diagnostic SOC and 6.1% for SOC-directed stone therapy. Limitations The study was observational in design with no control group. Conclusions Evaluation of bile duct disease and biliary stone therapy can be safely performed with a high success rate by using the SOC system.

A microscope laser light scattering setup has been developed that allows to carry out the intensity autocorrelation spectroscopy of the light scattered from a volume as small as (2 . tm)3. This noninvasive technique makes cytoplasmic studies possible inside single live biological cells. The technique has been proven powerful as revealed in the studies of hemoglobin aggregation within sickle red blood cells crystallin synthesis in the lens fiber cells and secretion of protein containing granules in the acinar cells. 1.

QLS is a now commonly used technique in biology, chemical physics and colloidal and macromolecular physics, mostly for particle sizing or velocimetry. In more special cases, QLS is used in the analysis of phase transitions and critical phenomena. The scattering volume is defined as the intersection of the illuminating laser beam and the region viewed by the collection optics. Most conventionally, QLS experiments are carried out on scattering volumes of (0.05 mm)3 to (1 mm)3. Needless to explain, this is much larger than most living cells.

In this study the interaction of gallbladder mucin subunits was examined by gel permeation chromatography, quasielastic laser light scattering, and viscometry. Purified mucin eluted primarily in the void volume of a Sepharose 2B-Cl column, indicating a molecular weight above 2 x 10(6). Disaggregation of the mucin polymer resulted in the elution of glycoprotein in the included volume of the Sepharose 2B-Cl column. Gallbladder mucin had a hydrodynamic radius of 630 A that was independent of mucin concentration below 2 mg/ml. At mucin concentrations above 2 mg/ml, a concentration-dependent increase in both hydrodynamic radius and apparent viscosity of gallbladder mucin was observed. Mucin demonstrated a strong pH dependence in hydrodynamic radius and viscosity with the maximum occurring at approximately pH 5.5. These findings suggest that noncovalent interactions participate in bovine gallbladder mucin subunit associations. Furthermore, changes that occur in the physicochemical environment of the gallbladder during periods of stasis may enhance the viscoelastic properties of mucin and promote the accumulation of biliary sludge in the gallbladder.

By using the technique of laser light-scattering spectroscopy, direct observation has been made on the intracellular accumulation of a crystallin protein within the cells of chicken embryo lens during the process of development. Appearance of delta-crystallin has been detected as early as day 4, and its concentration reaches a plateau at day 19. The measurements constitute a noninvasive determination of accumulation of protein molecules that specifically characterize the process of cell differentiation.

Actin is the major protein of eukaryote peripheral cytoplasm where its mechanical effects could determine cell shape and motility. The mechanical properties of purified F-actin, whether it is a viscoelastic fluid or an elastic solid, have been a subject of controversy. Mainstream polymer theory predicts that filaments as long as those found in purified F-actin are so interpenetrated as to appear immobile in measurements over a reasonable time with available instrumentation and that the fluidity of F-actin could only be manifest if the filaments were shortened. We show that the static and dynamic elastic moduli below a critical degree of shear strain are much higher than previously reported, consistent with extreme interpenetration, but that higher strain or treatment with very low concentrations of the F-actin severing protein gelsolin greatly diminish the moduli and cause F-actin to exhibit rheologic behavior expected for independent semidilute rods, and defined by the dimensions of the filaments, including shear rate independent viscosity below a critical shear rate. The findings show that shortening of actin filaments sufficiently to permit reasonable measurements brings out their viscoelastic fluid properties. Since gelsolin shortens F-actin, it is likely that the effect of high strain is also to fragment a population of long actin filaments. We confirmed recent findings that the viscosity of F-actin is inversely proportional to the shear rate, consistent with an indeterminate fluid, but found that gelsolin abolishes this unusual shear rate dependence, indicating that it results from filament disruption during the viscosity measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of microscope laser light-scattering spectroscopy allows for the measurement of dynamic properties of intracellular particles inside single fiber cells at different locations in the intact chicken embryo lens. Profiles of the diffusive properties of the delta-crystallin proteins across the lens are reported for developing chickens from day 5 to day 37. A clear decrease of the diffusion is observed in the lens nucleus relative to the cortex beginning with day 10.

The volume phase transition of submillimeter spherical isopropylacrylamide gels shows critical kinetic behavior near the critical point; the transition takes an infinite time, and the thermal expansion becomes infinitely large. At the critical point the gels also undergo internal critical density fluctuations as revealed by photon-correlation spectroscopy. The observation of critical kinetics along with critical dynamics clarifies the physical principle of the kinetics of gel volume change.