Patch Group Research Articles

Evaluation of the safety, tolerability and plasma vitamin D response to long-term use of patented transdermal vitamin D patches in healthy adults: a randomised parallel pilot study

BackgroundVitamin D delivered transdermally may suppress hyperactivity in nociceptor pain receptors and alter pain intensity, offering a useful addition to localised pain management in varying clinical settings. Currently, little is...

112. Deferoxamine Transdermal Application Decreases Fibrosis and Improves Elasticity in Irradiated Porcine Skin

Purpose: Radiation therapy is notorious for its effectiveness in oncologic treatment but its devastating side effects to the surrounding soft tissue. We have previously demonstrated the efficacy of a transdermal drug delivery system (TDDS) to deliver deferoxamine (DFO) cutaneously to irradiated porcine skin safely without any systemic effects. With this study, we aim to demonstrate the beneficial effects of deferoxamine on irradiated porcine skin. Methods: Six red Duroc pigs (three months old) were irradiated with a single fraction of 30 Gy bilaterally. The pigs were allowed to recover for 12 weeks to allow chronic fibrosis to develop. The pigs were then divided into 4 different treatment conditions: normal, non-irradiated skin, irradiated skin with no patch (IR control), vehicle patch, and 1.0mg DFO TDDS patch. The pigs were treated with daily patch changes for 4 weeks and harvested immediately following the 4 weeks of treatment of after waiting another 4 weeks post-treatment. Histological analysis and suction cutometer analysis were performed. P<0.05 was considered significant on statistical analysis. Results: Dermal thickness was noted to be significantly lower in the DFO cohort than the IR control or vehicle cohort at both 4 and 8 weeks post-treatment. Collagen ultrastructure was significantly different between the DFO treatment groups, more closely resembling the normal skin groups, compared to the no patch or vehicle patch groups. Collagen density was also significantly lower in the DFO cohort compared the vehicle or IR control groups. CD31+ expression was significantly higher in the DFO group compared to all other conditions except the normal skin. DFO also had significantly more elasticity than the IR control or vehicle group. Conclusion: DFO effectively treats radiation-induced fibrosis in a porcine model, allowing the skin to more closely resemble normal skin than irradiated skin.

Image restoration via exponential scale mixture‐based simultaneous sparse prior

Image prior plays a decisive role in the performance of widely studied model-based restoration methods. To further improve restoration performance, this paper proposes an exponential scale mixture-based simultaneous sparse prior (ESM-SSP) to accurately characterize image prior information. Specifically, first, two structured dictionaries are adaptively learned to explore the local and non-local sparsity of similar patch groups simultaneously. Then, the exponential scale mixture (ESM) is employed to model simultaneous sparse coefficients. The adoption of ESM enables us to accurately estimate simultaneous sparse coefficients by adaptively adjusting the regularization parameters. With the aid of ESM-SSP, an effective image restoration algorithm is developed to preserve more image details. Extensive experimental results on image denoising and deblocking demonstrate that compared with many state-of-the-art model-based methods, the proposed ESM-SSP-based restoration algorithm not only has competitive peak signal-to-noise ratio, but also produces higher structural similarity index and better visuals. More importantly, the proposed method can also compete favourably with the superior deep learning-based restoration methods.

Decellularized Bovine Pericardial Patch Loaded With Mesenchymal Stromal Cells Enhance the Mechanical Strength and Biological Healing of Large-to-Massive Rotator Cuff Tear in a Rat Model

The purpose of this study was to determine whether the addition of decellularized bovine pericardial patch loaded with mesenchymal stromal cells enhanced bone-to-tendon healing and improved the biomechanical strength of large-to-massive rotator cuff tears in a small animal model. Adipose-derived mesenchymal stromal cells (MSCs) from rat inguinal fat were isolated, cultured, and loaded onto decellularized bovine pericardium patches. To simulate large-to-massive tears, rats were managed with free cage activity for 6 weeks after tear creation. A total of 18 rats were randomly allocated to repair-only (control), repair with pericardial patch augmentation (patch), or repair with MSC loaded pericardial patch augmentation (patch-MSC). Each group had 6 rats (one shoulder of each rat was used for histological evaluation and another for biomechanical evaluation). MSCs seeded on the pericardial patches were traced on four shoulders from 2 other rats at 4 weeks after surgery. Histological evaluation for bone-to-tendon healing and biomechanical testing was carried out at 8 weeks after repair. MSCs tagged with a green fluorescent protein were observed in the repair site 4 weeks after the repair. One shoulder each in the control and patch groups showed complete discontinuity between the bone and tendon. One shoulder in the control group showed attenuation with only a tenuous connection. Fibrocartilage and tidemark formation at the bone-to-tendon interface (P= .002) and collagen fiber density (P= .040) and orientation (P= .003) were better in the patch-MSC group than in the control or patch group. Load-to-failure in the patch-MSC and patch groups was higher than that in the control group (P= .001 and .009, respectively). Decellularized bovine pericardial patches loaded with adipose-derived and cultured mesenchymal stromal cells enhanced healing in terms of both histology and mechanical strength at 8 weeks following rotator cuff repair in a rat model. Large-to-massive rotator tears need a strategy to prevent retear and enhance healing. The addition of decellularized bovine pericardial patch loaded with MSCs can enhance bone-to-tendon healing and improve biomechanical healing of large-to-massive rotator cuff tears following repair.

Single image denoising via multi-scale weighted group sparse coding

Nonlocal self-similarity (NSS) property of natural images, which means that the structure of the image sub-patches will appear repeatedly within a certain area, has been widely exploited as an effective prior to establishing various models in image denoising task. However, most of the existing NSS-based denoising models exploit the NSS prior in single scale only, and for some of the image patches that do not appear repeatedly, undesirable ringing artifacts will occur in the restored image, and even the image content may be lost. Considering the fact that NSS exists both within the same scale and across different scales, in order to better restore the structure and the edges of images contaminated by noise, we propose, in this paper, a novel multi-scale weighted group sparse coding model (MS-WGSC) for image denoising, wherein the patch groups are constructed using multi-scale NSS priors. Furthermore, an alternating minimization method is proposed to obtain the solution for our model. Extensive experiments are conducted that demonstrate the competitiveness of the proposed model compared with that of state-of-the-art methods not only in terms of the quantitative metrics such as PSNR and SSIM, but also in perceptual quality.

Increased stiffness and reoperation rate in partial rotator cuff repairs treated with a bovine patch: a propensity-matched trial

Treating high-grade (grade 2 and 3) partial-thickness rotator cuff tears after failed conservative care remains challenging. Arthroscopic repair techniques are often considered with or without subacromial decompression and biological injections. More recently, a bioinductive bovine collagen patch (Regeneten; Smith & Nephew, Memphis, TN, USA) has been proposed to create a healing response and thicken the injured tendon. Although promising early results have been shown, previous studies lacked control subjects or comparison to other surgical treatments. The purpose of this study was to compare the reoperation rates of arthroscopic débridement and repair without a bioinductive collagen patch vs. arthroscopic débridement and repair with a bioinductive collagen patch in patients with high-grade partial-thickness rotator cuff tears in whom a minimum of 6 months of nonoperative treatment failed. Thirty-two patients with high-grade partial-thickness supraspinatus tears were treated with surgical repair with a bioinductive patch. A control group of 32 patients with high-grade partial-thickness supraspinatus tears treated with débridement or tear completion and repair without a bioinductive patch was selected and matched for age, sex, and tear size. Patients were followed up at regular intervals of 6 weeks, 12 weeks, and 6 months postoperatively, and range of motion was assessed at respective clinic visits. Stiffness and reoperations were compared between groups. Postoperative stiffness was observed in the first 12 weeks in 8 of 32 patients in the patch group compared with 1 of 32 patients in the control group. Six patients in the patch group underwent reoperations compared with no patients in the control group (P<.001). All 6 reoperations in the patch group were performed to address stiffness. There were no differences in race, smoking status, or diabetes between groups (P>.05). Patients in the patch group had a significantly higher rate of postoperative stiffness. In the majority of patients in whom shoulder stiffness developed, reoperation was required.

Patch enlargement may not be a good strategy for treating tetralogy of Fallot with unbalanced pulmonary artery branches.

Our goal was to determine the optimal strategy for managing tetralogy of Fallot (TOF) with unbalanced pulmonary artery (PA) branches by investigating the different effects of PA plasty on the development of hypoplastic PA (HPA). A single-centre, retrospective analysis was carried out to compare the outcome of different PA plasty methods on the development of HPA in patients with TOF with unbalanced PA branches. Size and balance of the PA branches were used to evaluate the outcome of PA plasty. In the NATIVE group, 100% of the HPAs were well-developed and all PA branches became balanced, whereas in the PATCH and EXTENSION groups, the percentage of well-developed HPAs was 40% and 33%, respectively, and none of the PA branches were balanced. In addition, HPAs became atretic in 28% of the patients in the patch enlargement group. For TOF with unbalanced PA branches, patch enlargement may not be a good treatment strategy, because it reduces the growth potential of HPA and even causes iatrogenic atresia. Leaving the HPA in the native state without patch enlargement may be a good strategy.

Patch augmentation does not provide better clinical outcomes than arthroscopic rotator cuff repair for large to massive rotator cuff tears.

Patch augmentation for large and massive rotator cuff tears (LMRCTs) has been suggested as a repair strategy that can mechanically reinforce tendons and biologically enhance healing potential. The purpose of this study was to determine whether patients who underwent patch augmentation would have lower rates of retears and superior functional outcomes. Patients who underwent arthroscopic rotator cuff repair (ARCR) with patch augmentation (group A) were matched by age, sex, degree of retraction, and supraspinatus muscle occupation ratio to those treated with ARCR without using a patch (group B) with a minimum follow-up of 24months. The retear (Sugaya IV or V) rates were evaluated by magnetic resonance imaging at 3 and 12months post-surgery. The Constant- Murley Score (CMS), Korean Shoulder Score (KSS), and University of California-Los Angeles Shoulder Rating Scale (UCLA) score were retrospectively analyzed. This study included 34 patients (group A, n = 17; group B, n = 17). The mean follow-up period was 46.5 ± 17.4months. At postoperative 1-year follow-up, group B (6 patients, 35.3%) showed higher rates of retears than group A (1 patient, 5.9%), which was statistically significant (P = 0.034). However, the postoperative CMS, KSS, and UCLA scores did not differ between the two groups at 3months, 12months, and the final follow-up. Additionally, the clinical outcomes of patients with retear were not significantly different from those of the healed patients in both groups. The use of an allodermal patch for LMRCT is effective in preventing retears without complications. However, the clinical outcomes of ARCR using allodermal patch augmentation were not superior to those of only ARCR. III.

Electronic cigarettes versus nicotine patches for smoking cessation in pregnancy: a randomized controlled trial

Nicotine replacement therapy, in the form of nicotine patches, is commonly offered to pregnant women who smoke to help them to stop smoking, but this approach has limited efficacy in this population. Electronic cigarettes (e-cigarettes) are also used by pregnant women who smoke but their safety and efficacy in pregnancy are unknown. Here, we report the results of a randomized controlled trial in 1,140 participants comparing refillable e-cigarettes with nicotine patches. Pregnant women who smoked were randomized to e-cigarettes (n = 569) or nicotine patches (n = 571). In the unadjusted analysis of the primary outcome, validated prolonged quit rates at the end of pregnancy in the two study arms were not significantly different (6.8% versus 4.4% in the e-cigarette and patch arms, respectively; relative risk (RR) = 1.55, 95%CI: 0.95–2.53, P = 0.08). However, some participants in the nicotine patch group also used e-cigarettes during the study. In a pre-specified sensitivity analysis excluding abstinent participants who used non-allocated products, e-cigarettes were more effective than patches (6.8% versus 3.6%; RR = 1.93, 95%CI: 1.14–3.26, P = 0.02). Safety outcomes included adverse events and maternal and birth outcomes. The safety profile was found to be similar for both study products, however, low birthweight (<2,500 g) was less frequent in the e-cigarette arm (14.8% versus 9.6%; RR = 0.65, 95%CI: 0.47–0.90, P = 0.01). Other adverse events and birth outcomes were similar in the two study arms. E-cigarettes might help women who are pregnant to stop smoking, and their safety for use in pregnancy is similar to that of nicotine patches. ISRCTN62025374.

Comparison of the effectiveness of amblyopia treatment with eye-patch and binocular Occlu-tab for the same treatment duration.

Purpose:This study aimed to compare the conventional eye patch with Occlu-tab—a binocular open-type amblyopia training device—and evaluate their effectiveness in amblyopia treatment.Methods:In this prospective, multi-center study, 40 patients between ages 3 to 12 years, diagnosed with anisometropic amblyopia (refraction difference of both eyes ≥ 2 D, best-corrected visual acuity [BCVA] of the amblyopic eye ≤ 0.1 [logMAR]) were treated with Occlu-tab or conventional eye patch for 1 h per day thrice a week. We compared the visual acuity of both groups before and after 6, 7, and 8 weeks of amblyopia treatment. One-way repeated-measures analysis of variance and Tukey’s test were used to compare the visual acuity of both groups pre- and post-treatment.Results:Both groups had significantly improved visual acuity at 6, 7, and 8 weeks compared to that before treatment (all P < 0.001). The improvement in BCVA of the Occlu-tab group (0.33 ± 0.25) was significantly greater than that of the eye patch group (0.16 ± 0.17) after 8 weeks of treatment (P = 0.02).Conclusion:Amblyopia treatment using binocular open game training with Occlu-tab led to greater improvement in visual acuity than that with a conventional eye patch for the same treatment duration.

Gaussian mixture model based phase prior learning for video motion estimation

Optic measurement nowadays shows more prominent features over the traditional sensor-based measurement techniques as it does not need sensor installment and can provide simultaneous measurements with very high spatial resolution. Phase-based video processing has been widely used in optic measurement for capturing small motions. It relies on the assumptions that the variance of noise has to be much lower than the pure signal and small motions are encoded in the phase shift of an individual pixel’s color which fundamentally restricts its usefulness. To tackle these issues, this paper proposes a novel perspective of phase estimation by utilizing the image priors on phase patches. The patch group based Gaussian Mixture Model (PG-GMM) learning algorithm is used to learn the nonlocal self-similarity (NSS) prior from training images. Then the phase information is modeled by learned patch group priors, and further optimized using the steps of gaussian component selection and weighted sparse coding. The proposed method is validated in both magnification and modal analysis applications in the example analysis. Compared to the phase-based method, the proposed method achieves high-quality magnifications on the real video signal, with fewer artifacts and better anti-noise performance. Clearer time-domain motion estimates of video components can also be extracted by the proposed method.

Application of Biosheets as Right Ventricular Outflow Tract Repair Materials in a Rat Model

PurposesWe report the experimental use of completely autologous biomaterials (Biosheets) made by “in-body tissue architecture” that could resolve problems in artificial materials and autologous pericardium. Here, Biosheets were implanted into full-thickness right ventricular outflow tract defects in a rat model. Their feasibility as a reparative material for cardiac defects was evaluated.MethodsAs the evaluation of mechanical properties of the biosheets, the elastic moduli of the biosheets and RVOT-free walls of rats were examined using a tensile tester. Biosheets and expanded polytetrafluoroethylene sheet were used to repair transmural defects surgically created in the right ventricular outflow tracts of adult rat hearts (n = 9, each patch group). At 4 and 12 weeks after the operation, the hearts were resected and histologically examined.ResultsThe strength and elastic moduli of the biosheets were 421.3 ± 140.7 g and 2919 ± 728.9 kPa, respectively, which were significantly higher than those of the native RVOT-free walls (93.5 ± 26.2 g and 778.6 ± 137.7 kPa, respectively; P < 0.005 and P < 0.001, respectively). All patches were successfully implanted into the right ventricular outflow tract-free wall of rats. Dense fibrous adhesions to the sternum on the epicardial surface were also observed in 7 of 9 rats with ePTFE grafts, whereas 2 of 9 rats with biosheets. Histologically, the vascular-constructing cells were infiltrated into Biosheets. The luminal surfaces were completely endothelialized in all groups at each time point. There was also no accumulation of inflammatory cells.ConclusionsBiosheets can be formed easily and have sufficient strength and good biocompatibility as a patch for right ventricular outflow tract repair in rats. Therefore, Biosheet may be a suitable material for reconstructive surgery of the right ventricular outflow tract.

Comparison of Omental Patch Closure Versus Simple Closure for Laparoscopic Repair of Perforated Peptic Ulcer: A Systematic Review and Meta-Analysis.

To evaluate comparative outcomes of laparoscopic repair of perforated peptic ulcer with omental patch versus without omental patch. A systematic search of multiple electronic data sources was conducted, and all studies comparing laparoscopic repair of perforated peptic ulcer (PPU) with and without omental patch were included. Operative time, postoperative complications, re-operation and mortality were the evaluated outcome parameters for the meta-analysis. Revman 5.3 was used for data analysis. Four observational studies reporting a total number of 438 patients who underwent laparoscopic repair of PPU with (n = 268) or without (n = 170) omental patch were included. Operative time was significantly shorter in no-omental patch group (NOP) when compared to omental patch group (P = .02). There was no significant difference in the risk of postoperative ileus (Odd ratio (OR) .76, P = .61), leakage (OR 1.17, P = .80), wound infection (OR 1.89, P = .34), intra-abdominal abscess (OR 1.17, P = .87), re-operation (OR .00, P = .94) and mortality (OR .55, P = .48). Moreover, length of hospital stay was comparable between the two groups (P = .81). Laparoscopic repair of PPU with or without omental patch have comparable postoperative complications and mortality rate. However, considering the shorter operative time, no-omental patch approach is an attractive and more favourable choice. Well-designed randomized controlled trials are needed to investigate this comparison.

Flouroscopic versus conventional epidural blood patch in obstetrics: A retrospective cohort study.

Epidural blood patch is a common effective treatment for postdural puncture headache after accidental dural puncture during labor and may be done in conventional or fluoroscopy-guided methods. The aim of this study was to compare intensity of headache at the time of discharge from the hospital and to compare blood volumes injected in conventional epidural blood patches versus fluoroscopic-guided blood patches and evaluate the side effects of both method of treatment. Between the years 2010 and 2020, 84 patients who were diagnosed with postdural puncture headache received either a conventional epidural blood patch or a fluoroscopic-guided blood patch. Blood volumes were compared and evaluation of side effects was made based on data collected during and after the procedure. Eighty-four patients were included in this study. Fifty-two women in the conventional epidural blood patch group and 32 in the fluoroscopic-guided blood patch group. Women in the conventional epidural blood patch group received statistically significantly higher doses of blood than women in the fluoroscopic-guided blood patch group: conventional method 29ml IQR [23-36] versus fluoroscopic method 16ml, IQR [12-18], p<.001 with no difference in headache pain intensity at hospital release. There was no difference between groups in hospital length of stay, or persistent PDPH. There was also no difference chronic headache or backache between the two groups. Women who received fluoroscopic epidural blood patch required a much lower volume of blood injected while there was no difference between groups in headache pain intensity at discharge.

Image restoration algorithm based on multiscale weighted Schatten p-norm minimization

Image restoration is the process of restoring an image from a degraded version, which is usually blurred and noisy. We are motivated by the problem of restoring blurred and noisy images using multiscale weighted Schatten p-norm minimization, which not only gives a better approximation to the original low-rank hypothesis but also considers the importance of different rank components. Similar patches are vectorized and grouped to construct a noisy low-rank matrix. Weighted Schatten p-norm minimization values of all image patch groups are simultaneously penalized by a new regularization term, which can represent both the sparsity and self-similarity of the image structure accurately. In addition, by calculating the similarity of patches on different scales of the image, the restoration effect of the image is further improved. The experimental results show that our method is superior to some existing excellent algorithms in both numerical and visual effects.

Aortic valve repair using pericardial patch standardized with external ring annuloplasty.

This study was undertaken to analyse outcomes of aortic valve repair using additional material and compare the results to those of cusp repair without the use of the pericardial patch. All consecutive patients aged over 16 who underwent aortic valve repair with external ring annuloplasty for isolated aortic insufficiency, aortic insufficiency and tubular aortic aneurysm or aortic root aneurysm between May 2003 and November 2019 were included in a cohort study. Data were collected and analysed from the AVIATOR registry (AorticValve repair InternATiOnal Registry). Propensity score framework analysis (inverse probability of treatment weighting) was used to compare outcomes of the groups while controlling for confounders. During the 16-year study period, 618 patients underwent aortic valve repair. Eight-year survival rate was 92% in the patch group and 90.2% in the no patch group without significant differences [P = 0.957 inverse probability of treatment weighting (IPTW) weighted]. Early valve-related reoperation was more frequent in the patch group as compared to the no patch group (6% vs 1%, P < 0.001 IPTW weighted), the freedom from aortic valve-related reintervention and from structural valve deterioration at 8 years was not significantly different between the patch and no patch groups (93.7% vs 94%, P = 0.968 IPTW weighted; and 99.3% vs 96.7%, P = 0.964 IPTW weighted). Although a higher rate of early reintervention was observed, aortic valve repair using the pericardial patch, in a standardized approach using external annuloplasty, with effective coaptation height of at least 9 mm, was not associated with an increase in mid-term aortic valve-related reoperation or structural valve deterioration as compared to valve repair without the pericardial patch.

Effectiveness of the Fibrinogen-Thrombin-Impregnated Collagen Patch in the Prevention of Postoperative Complications after Parotidectomy: A Single-Blinded, Randomized Controlled Study

We investigated whether a fibrinogen-thrombin collagen sponge patch reduces postoperative complications of parotid gland surgery. This single-blinded, randomized controlled study included 165 patients who underwent parotid surgery for benign tumors (2018–2019) at a tertiary center. Primary outcomes were postoperative drain amount, days until drain removal, and discharge. Patients were scheduled for follow-up at 1 and 4 weeks, and 3 months after surgery. Complications including surgical site infection, pain, seroma, sialocele, salivary fistula, facial nerve palsy, Frey’s syndrome with subjective symptoms, and facial asymmetry were analyzed. After identifying confounding variables, multivariate approaches were used. Histologic analysis was performed in a mouse model of salivary gland surgery. In total, 162 patients (77, fibrinogen-thrombin collagen patch group; 85, controls) were included, with no significant between-group differences other than resected tissue. Among postoperative total drain amount and days until drain removal and discharge, the only postoperative total drain was significantly lower in the patch group than in the control group in the adjusted model. Additionally, although validation through robust trials with longer follow-up is needed, we found the potential benefit of the fibrinogen patch on Frey’s syndrome and facial asymmetry. In conclusion, fibrinogen-thrombin-impregnated collagen patches in parotidectomy can reduce postoperative drainage and improve outcomes.

Phase retrieval from incomplete data via weighted nuclear norm minimization

Recovering an unknown object from the magnitude of its Fourier transform is a phase retrieval problem. Here, we consider a much difficult case, where those observed intensity values are incomplete and contaminated by both salt-and-pepper and random-valued impulse noise. To take advantage of the low-rank property within the image of the object, we use a regularization term which penalizes high weighted nuclear norm values of image patch groups. For outliers (impulse noise) in the observation, the ℓ1−2 metric is adopted as the data fidelity term. Then we break down the resulting optimization problem into smaller ones, for example, weighted nuclear norm proximal mapping and ℓ1−2 minimization, because the nonconvex and nonsmooth subproblems have available closed-form solutions. The convergence results are also presented, and numerical experiments are provided to demonstrate the superior reconstruction quality of the proposed method.

Infrared and visible image fusion via rolling guidance filter and weight map

The main task of image fusion is to extract the advantage information from the source images. Multiscale transform (MST) is commonly used in image fusion, but it is difficult to integrate detail information and structural information from source images. Therefore, it is important to integrate the information in each image patch group. Different from MST, edge preserving technology obtains more edge information than MST by extracting spatial information. Based on this superior feature, we propose an infrared and visible image fusion method via rolling guidance filter (RGF) and weight map. First, source images are decomposed into multiscale detail layers and structural base layers by RGF; second, to avoid the loss of local information, the modified Laplacian energy weight matrix is used as detail weight maps to merging the detail layers; then to reduce the loss of contours of edge objects, a structural weight maps are used to merging the base layers; finally, these two different weight maps are applied to reconstruct the fused image. Simulation results indicate that our fusion approach performs better in merging detail information and structural information than some classic MST fusion algorithms and the latest fusion methods.

Group Sparsity Mixture Model and Its Application on Image Denoising.

Prior learning is a fundamental problem in the field of image processing. In this paper, we conduct a detailed study on (1) how to model and learn the prior of the image patch group, which consists of a group of non-local similar image patches, and (2) how to apply the learned prior to the whole image denoising task. To tackle the first problem, we propose a new prior model named Group Sparsity Mixture Model (GSMM). With the bilateral matrix multiplication, the GSMM can model both the local feature of a single patch and the relation among non-local similar patches, and thus it is very suitable for patch group based prior learning. This is supported by the parameter analysis which demonstrates that the learned GSMM successfully captures the inherent strong sparsity embodied in the image patch group. Besides, as a mixture model, GSMM can be used for patch group classification. This makes the image denoising method based on GSMM capable of processing patch groups flexibly. To tackle the second problem, we propose an efficient and effective patch group based image denoising framework, which is plug-and-play and compatible with any patch group prior model. Using this framework, we construct two versions of GSMM based image denoising methods, both of which outperform the competing methods based on other prior models, e.g., Field of Experts (FoE) and Gaussian Mixture Model (GMM). Also, the better version is competitive with the state-of-the-art model based method WNNM with about ×8 faster average running speed.