Surgical Site Infections in Gastroenterological Surgery

Surgical site infections (SSIs) remain one of the most common serious surgical complications and are the second most frequent healthcare-associated infection. Patients with SSIs have a significantly increased postoperative length of hospital stay, hospital expenses, and mortality risk compared with patients without SSIs. The prevention of SSI requires the integration of a range of perioperative measures, and approximately 50% of SSIs are preventable through the implementation of evidence-based preventative strategies. Several international guidelines for SSI prevention are currently available worldwide. However, there is an urgent need for SSI prevention guidelines specific to Japan because of the differences in the healthcare systems of Japan versus western countries. In 2018, the Japan Society for Surgical Infection published SSI prevention guidelines for gastroenterological surgery. Although evidence-based SSI prevention guidelines are now available, it is important to consider the appropriateness of these guidelines depending on the actual conditions in each facility. A systemic inflammatory host response is a hallmark of bacterial infection, including SSI. Therefore, blood inflammatory markers are potentially useful in SSI diagnosis, outcome prediction, and termination of therapeutic intervention. In this review, we describe the current guideline-based perioperative management strategies for SSI prevention, focusing on gastroenterological surgery and the supplemental utility of blood inflammatory markers.

The prediction of pathological complete response after total neoadjuvant therapy for locally advanced rectal cancer using versatile liquid biopsy

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Background: Total neoadjuvant therapy (TNT) has conferred a dramatic paradigm shift in the treatment for locally advanced rectal cancer (LARC), which can prolong the survival associated with high pathological complete response (pCR) rate and introduce non-operative management (NOM). However, useful biomarkers predicting the treatment efficacy of TNT and the prognosis has not been developed. Our previous study demonstrated that volume of blood long- and short-fragments DNA ( > 300 bp and < 180 bp) in LINE-1 gene are derived from tumor cell necrosis, and normal cell apoptosis, and the ratio (LSR) could reflect tumor growth or shrinkage, and minimal residual disease. Methods: A total of 17 LARC patients receiving consolidation TNT consisting of short-course radiation (5Gy x 5days) and 4 courses of CapOX, followed by total mesorectal excision were included. Blood concentrations of long-, short-fragment DNA and LSR in neoadjuvant phase were serially measured at pre-treatment, every treatment cycle, and pre-operation by real-time PCR. Results: Median age of patients were 64 years old and 65% were female. Clinical stage (IIa/IIc/IIIb/IIIc) were 2/1/8/6, respectively. Down staging was shown in 88% of patients. Tumor regression grade (0/1a/1b/2/3(pCR)) were 1/2/3/34/7(41%), respectively. Only 44% of patients had elevated CEA levels before TNT, which indicates less usefulness as the biomarker. The dynamics of the LSR in the entire cohort showed the gradual decrease until pre-operative phase (decrease to 77.8%). The LSR change from pre-treatment (or just after SCRT) to early preoperative treatment phase (1 or 2 course after CapOX) was significantly greater in the pCR(+)(n = 7) than the pCR(-)(n = 10) groups (66.8% vs. 101%, p = 0.03). The AUC of ROC analysis was 0.72 (cut off: 66.8%). Conclusions: NGS based liquid biopsy is the gold standard for the cancer prediction and monitoring, but limitations such as unsatisfied sensitivity and high cost are still involved. However, LSR measurement has great benefits on those points. Early phase LSR measurement could be a good predictive marker for the response of TNT and might be clinically useful for optimizing the preoperative therapy.

[Is Cell-Free DNA a Useful Biomarker for Predicting the Efficacy of Preoperative Chemotherapy for Advanced Colon Cancer?]

OBJECTIVE

To examine the potential of peripheral circulating cell-free DNA(cfDNA)as a predictor of response in patients undergoing neoadjuvant chemotherapy(NAC)for advanced colon cancer.

METHODS

We compared histological response, background factors, and cfDNA molecular volume changes in cT4 and cT3N+ colon cancer patients.

RESULTS

Six of 11 patients responded. The patients with muc and pap histology were non-responders. There was no relationship between CEA or cfDNA levels and response. Responders showed >50% change in DNA integrity index(=cfDNA long fragment/ short fragment ratio), while non-responders showed <50% change(p=0.015).

CONCLUSION

Our results suggest that the variability rate in DNA integrity index of peripheral blood cfDNA may be useful in predicting the therapeutic efficacy of colon NAC.

[Long-Term Response to UFT/UZEL/Bevacizumab Therapy for Lung Metastasis after Surgery for Early-Stage Colon Cancer in a Late-Stage Elderly Patient]

Late-stage elderly patients have low tolerance to chemotherapy, and they have difficulties when they are treated with standard chemotherapy. We report a case of a late-stage elderly patient who had a long-term response to UFT/UZEL/bevacizumab( Bev)therapy for lung metastasis after surgery for early-stage colon cancer. He was 82-years-old and underwent laparoscopy-assisted sigmoid colectomy for sigmoid colon cancer at another hospital. The pathological diagnosis was pT1b, ly1, v0, N0, M0, pStage Ⅰ. Six months after the surgery, a small nodule was noted in the middle lobe of the right lung. It grew five months later and was definitely diagnosed as lung metastasis. Considering his physical condition and tumor size, we opted to introduce less invasive chemotherapy instead of standard chemotherapy. UFT/UZEL/Bev was started 14 months after surgery. Although he required dose reduction due to anorexia, he safely continued the treatment with partial response (PR), which was maintained for 2 years and 6 months. While UFT/UZEL/Bev has no convincing evidence, it may be an option for vulnerable patients, especially those with non-life-threatening disease.

TGF-β1 increases cellular invasion of colorectal neuroendocrine carcinoma cell line through partial epithelial-mesenchymal transition

Epithelial–mesenchymal transition (EMT) plays a pivotal role in cancer progression and metastasis in many types of malignancies, including colorectal cancer. Although the importance of EMT is also considered in colorectal neuroendocrine carcinoma (NEC), its regulatory mechanisms have not been elucidated. We recently established a human colorectal NEC cell line, SS-2. In this study, we aimed to clarify whether these cells were sensitive to transforming growth factor beta 1 (TGF-β1) and whether EMT could be induced through TGF-β1/Smad signaling, with the corresponding NEC cell-specific changes in invasiveness. In SS-2 cells, activation of TGF-β1 signaling, as indicated by phosphorylation of Smad2/3, was dose-dependent, demonstrating that SS-2 cells were responsive to TGF-β1. Analysis of EMT markers showed that mRNA levels changed with TGF-β1 treatment and that E-cadherin, an EMT marker, was expressed in cell-cell junctions even after TGF-β1 treatment. Invasion assays showed that TGF-β1-treated SS-2 cells invaded more rapidly than non-treated cells, and these cells demonstrated increased metalloproteinase activity and cell adhesion. Among integrins involved in cell-to-matrix adhesion, α2-integrin was exclusively upregulated in TGF-β1-treated SS-2 cells, but not in other colon cancer cell lines, and adhesion and invasion were inhibited by an anti-α2-integrin blocking antibody. Our findings suggest that α2-integrin may represent a novel therapeutic target for the metastasis of colorectal NEC cells.

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NEC cell line SS-2 is responsive to TGF-β1.

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TGF-β1 stimulation induces partial EMT, maintaining E-cadherin in SS-2 cells.

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TGF-β1-treated SS-2 cells exhibit increase in metalloproteinase activity and cell adhesion.

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α2-integrin is exclusively upregulated in TGF-β1-treated SS-2 cells.

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Use of anti-α2-integrin blocking antibody inhibits enhanced adhesion and invasion.

A rapidly growing small intestinal metastasis from lung cancer

Small intestinal metastasis from lung cancer is a relatively rare occurrence, and often causes intestinal obstruction, gastrointestinal perforation, and/or gastrointestinal bleeding making it is an oncological emergency. Many patients have been reported to undergo emergency surgery owing to the rapid progression of the intestinal metastatic lesion; however, information regarding the changes that occur in such metastases over time remains lacking. Therefore, we analyzed 4 patients who had small intestinal metastases arising from lung cancer, who were treated during a 10-year period (January 2011 to December 2020), and whose tumor diameter changes were recorded. The average tumor volume growth rate was 1.48 (1.31-1.78) -fold, and the median observation period was 22 (4-39) days, showing a rapid increase. Histopathologically, in patients with a high degree of primary tumor atypia, rapid tumor growth caused by intratumoral hemorrhage may occur. This was considered to be one of the factors responsible for the rapid increase in tumor volume.

Apical leakage of obturated canals prepared by Er:YAG laser

The present study evaluates the degree of apical leakage in vitro after root canal preparation using Er:YAG laser irradiation followed by obturation. Twenty-four single-rooted teeth were divided into 2 groups of 12. One group served as a control and these root canals were conventionally prepared up to a #50K file. The other group was prepared by Er:YAG laser irradiation at parameters of 2 Hz and 170 to 230 mJ/pulse. After obturation the teeth were immersed in a vacuum flask containing 0.6% rhodamine for 48 h, longitudinally bisected, and observed by stereoscopy and scanning electron microscopy. The degree of apical leakage from an apical stop was measured and statistical analysis was performed. The degree of apical leakage from the teeth prepared by laser was not significantly less than that from control teeth (p > 0.01). Morphological findings showed that contact between the root canal walls and obturated materials was hermetic in both groups, but canal walls prepared by laser were rough and irregular. These results show that root canal preparation by laser does not affect apical leakage after obturation compared with leakage in canals prepared using the conventional method.

Treatment of dentine hypersensitivity by lasers: a review

BACKGROUND, AIMS

Since the development of the ruby laser by Maiman in 1960, a variety of papers on potential applications for lasers in dentistry have been published. The purpose of this paper is to summarise laser applications for the treatment of dentine hypersensitivity. The effects of laser on pulp tissue and problems on laser treatment are also reviewed. This article reviews the role of lasers for the treatment of dentine hypersensitivity since 1985, summarises many research reports from the last decade, and surmises what the future may hold for lasers in this treatment.

METHOD

To date, 4 kinds of lasers have been used for the treatment of dentine hypersensitivity, and the effectiveness ranged from 5.2 to 100%, which was dependent on the laser type and parameters used. The mechanism involved in laser treatment of dentine hypersensitivity are relatively unknown.

RESULTS

These require clarification to result in safely effective treatment optimization. In general, the efficiency for the treatment of dentine hypersensitivity using lasers is higher than other methods, but in severe cases, it is less effective.

CONCLUSION

It is necessary to consider the severity of dentine hypersensitivity before laser use.

Morphological study on the capability of Er:YAG laser irradiation for root canal preparation

OBJECTIVE

The purpose of this study was to evaluate morphologically the capability of Er:YAG laser irradiation for root canal preparation in vitro.

BACKGROUND DATA

There have been no reports on root canal preparation using Er:YAG laser irradiation.

METHODS

Forty extracted human teeth were divided randomly into two groups of 20. Laser irradiation was performed using three different sizes of fiber tips at the two different parameters (G 1, 2 Hz and 136-184 mJ/pulse; G 2, 2 Hz and 170-230 mJ/pulse). After laser irradiation, the teeth were bisected longitudinally and observed by stereoscopy and field emission-scanning electron microscopy (FE-SEM). The time required for preparation in each group was recorded and the achievement degree of root canal preparation was scored according to our criteria. Statistical analysis of the times was performed using one-way analysis of variance (ANOVA). A value of p < 0.01 was considered significant.

RESULTS

Root canals were prepared using laser irradiation at 50% of teeth in G 1 and 40% in G 2. Remnant pulp tissue after laser irradiation was observed at 30% of teeth in G 1, but not recognized in G 2. Irradiated areas were scale-like and clean, but rough and irregular by FE-SEM. The statistical analysis revealed that the time required for preparation at high energies was significantly shorter compared with that at low energies (p < 0.01).

CONCLUSION

These results suggest that Er:YAG laser irradiation is capable of root canal preparation if appropriate parameters are selected.

Treatment of cervical dentin hypersensitivity by various methods using pulsed Nd:YAG laser

OBJECTIVE

The purpose of this study was to evaluate the results of two irradiated regions, the cervical and apical, for cervical dentin hypersensitivity treatment using pulsed a Nd:YAG laser with or without black ink.

SUMMARY BACKGROUND DATA

There has been no reports on the irradiated area(s) except the cervical region for dentin hypersensitivity treatment using pulsed Nd:YAG laser.

METHODS

A total of 180 teeth diagnosed with cervical dentin hypersensitivity in 54 (39 females, 15 males, aged 21 to 73) healthy adult patients were included in this study, and teeth were randomly divided into four groups of 45 each. Sensitivity was rated using a blast from a fully depressed air syringe on a four-grade scale both before and up to 2 months after laser treatment. The effectiveness was evaluated on the change in the degree of hypersensitivity after laser treatment. The tooth surfaces in groups 1 and 2 were observed by the replica model method using scanning electron microscopy (SEM).

RESULTS

The methods of irradiation at the cervical regions were better than those at the apical regions except for the period 2 months later. The laser effect was enhanced by black ink at both areas. The effective (excellent and good) rate was decreased depending on the time in every group. SEM observation at the tooth surfaces from group 2 showed that dentinal tubules were occluded or narrowed after laser irradiation.

CONCLUSIONS

These results show that the method of irradiation by a pulsed Nd:YAG laser at cervical regions with black ink is the most effective for cervical dentin treatment of hypersensitivity and recurrence by this method is less than in other methods.

Study of microleakage at Class I cavities prepared by Er:YAG laser using three types of restorative materials

OBJECTIVE

The purpose of this in vitro study were to investigate microleakage at class I cavities filled with amalgam, composite resin, or glass-ionomer after preparation by Er:YAG laser and to compare the results with those by a conventional method using an air turbine.

SUMMARY BACKGROUND DATA

There has been no report of a study of microleakage on class I cavities prepared by Er:YAG laser.

METHODS

Ninety-six extracted human premolar and molar teeth were used in this study. Forty-eight class I cavities were prepared by Er:YAG laser and 48 class I cavities by air turbine. After preparation, each of the 2 groups was further subdivided into 3 groups, respectively, and cavities in each of these subgroups were filled by 1 of 3 types of restorative materials. Microleakage at the restored cavities was assessed by the dye penetration method and scanning electron microscopy (SEM).

RESULTS

Minimal or moderate leakage was evident at most of the composite resin or glass-ionomer restorations, whereas moderate or severe leakage was observed at most of the amalgam restorations as shown by the dye penetration method. There was significant difference among the 3 restorative materials (p < 0.05), but there was no significant difference in microleakage between the cavities prepared by Er:YAG laser and those by air turbine (p > 0.05). SEM evaluation demonstrated good adaptation with most of the composite resin or glass-ionomer restorations, but amalgam restorations showed slightly poorer adaptation.

CONCLUSION

These results suggest that Er:YAG laser is useful for class I cavity preparation from the viewpoint of microleakage.