Molecular and Cellular Mechanisms of Delayed Fracture Healing in Mmp10 (Stromelysin 2) Knockout Mice

The remodeling of the extracellular matrix is a central function in endochondral ossification and bone homeostasis. During secondary fracture healing, vascular invasion and bone growth requires the removal of the cartilage intermediate and the coordinate action of the collagenase matrix metalloproteinase (MMP)-13, produced by hypertrophic chondrocytes, and the gelatinase MMP-9, produced by cells of hematopoietic lineage. Interfering with these MMP activities results in impaired fracture healing characterized by cartilage accumulation and delayed vascularization. MMP-10, Stromelysin 2, a matrix metalloproteinase with high homology to MMP-3 (Stromelysin 1), presents a wide range of putative substrates identified in vitro, but its targets and functions in vivo and especially during fracture healing and bone homeostasis are not well defined. Here, we investigated the role of MMP-10 through bone regeneration in C57BL/6 mice. During secondary fracture healing, MMP-10 is expressed by hematopoietic cells and its maximum expression peak is associated with cartilage resorption at 14 days post fracture (dpf). In accordance with this expression pattern, when Mmp10 is globally silenced, we observed an impaired fracture-healing phenotype at 14 dpf, characterized by delayed cartilage resorption and TRAP-positive cell accumulation. This phenotype can be rescued by a non-competitive transplant of wild-type bone marrow, indicating that MMP-10 functions are required only in cells of hematopoietic linage. In addition, we found that this phenotype is a consequence of reduced gelatinase activity and the lack of proMMP-9 processing in macrophages. Our data provide evidence of the in vivo function of MMP-10 during endochondral ossification and defines the macrophages as the lead cell population in cartilage removal and vascular invasion. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).     

Duodenopancreatectomía cefálica y tutorización externa del conducto de Wirsung. Resultados de una serie de 80 casos consecutivos

IntroductionThere is controversy regarding the ideal pancreaticojejunostomy technique after pancreaticoduodenectomy. Many authors consider the external Wirsung stenting technique to be associated with a low incidence of fistula, morbidity and mortality. We analyse our experience with this technique.Patients and methodsA retrospective analysis of the morbidity and mortality of a series of 80 consecutive patients who had been treated surgically over a 6.5-year period for pancreatic head or periampullary tumors, performing pancreaticoduodenectomy and pancreaticojejunostomy with external Wirsung duct stenting.ResultsMean patient age was 68.3 ± 9 years, and the resectability rate was 78%. The texture of the pancreas was soft in 51.2% of patients and hard in 48.8%. Pylorus-preserving resection was performed in 43.8%. Adenocarcinoma was the most frequent tumor (68.8%), and R0 was confirmed in 70% of patients. Biochemical fistula was observed in 11.2%, pancreatic fistula grade B in 12.5% and C in 2.5%, whereas the abdominal reoperation rate was 10%. Median postoperative hospital stay was 16 days, and postoperative and 90-day mortality was 2.5%. Delayed gastric emptying was observed in 36.3% of patients, de novo diabetes in 12.5%, and exocrine insufficiency in 3. Patient survival rates after 1, 3 and 5 years were 80.2, 53.6 and 19.2%, respectively.ConclusionsAlthough our low rates of postoperative complications and mortality using external Wirsung duct stenting coincides with other more numerous recent series, it is necessary to perform a comparative analysis with other techniques, including more cases, to choose the best reconstruction technique after pancreaticoduodenectomy.     

The Landmark Series: Surgical Treatment of Colorectal Cancer Peritoneal Metastases

Background

Peritoneal metastases (PM) are a form of metastatic spread affecting approximately 5-15% of colon cancer patients. The attitude towards management of peritoneal metastases has evolved from therapeutic nihilism towards a more comprehensive and multidisciplinary approach, in large part due to the development of cytoreductive surgery (CRS), usually coupled with heated intraperitoneal chemotherapy (HIPEC), along with the constant improvement of systemic chemotherapy of colorectal cancer. Several landmark studies, including 5 randomized controlled trials have marked the development and refinement of surgical approaches to treating colorectal cancer peritoneal metastases.

Methods

This review article focuses on these landmark studies and their influence in 4 key areas: the evidence supporting surgical resection of peritoneal metastases, the identification and standardization of important prognostic variables influencing patient selection, the role of surgery and intraperitoneal chemotherapy in prevention of colorectal PM and the role of intraperitoneal chemotherapy as an adjuvant to surgical resection.

Results

These landmark studies indicate that surgical resection of colorectal PM should be considered as a therapeutic option in appropriately selected patients and when adequate surgical expertise is available. Standardized prognostic variables including the Peritoneal Cancer Index and the Completeness of Cytoreduction Score should be used for evaluating both indications and outcomes.

Conclusions

Current evidence does not support the use of second look surgery with oxaliplatin HIPEC or prophylactic oxaliplatin HIPEC in patients with high risk colon cancer nor the use of oxaliplatin HIPEC with CRS of colorectal PM.

     

Born this Way–or Not? The Relationship Between Essentialism and Sexual Minorities’ LGBTQ+ Identification and Belonging

Archives of Sexual Behavior - Bisexual people experience lower levels of belonging in the LGBTQ+ community than gay and lesbian people. We investigated one of the factors that may reduce bisexual...     

Genetic markers in primary open-angle glaucoma

Purpose: To investigate possible associations between genetic markers and Primary Open-Angle Glaucoma (POAG). Methods: A number of genetic markers were typed in 84 unrelated patients with POAG and compared with a random sample of healthy individuals. The markers were Transferrin, Group Specific Component, G1m (1), G1m (2) and G3m (5) Allotypes, Adenylate Kinase, Adenosin Deaminase, Glyoxalase I and Acid Phosphatase and PCR-based markers HLA-DQA1 and D1S80. Results: No significant differences were found except the strong association between the group of POAG patients and Acid Phosphatase ACP^*C allele (² = 32.86; p < 0.0001). Conclusions: Since Acid Phosphatase gene is localized to chromosome 2p23, this result could be a first comprehensive step in the localization of POAG genes.     

Inward transport of 3H-MPP+ in freshly isolated rat hepatocytes: evidence for interaction with catecholamines

1-Methyl-4-phenylpyridinium (MPP⁺), the neurotoxic metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), is efficiently taken up and accumulated by rat hepatocytes. However, the nature of the mechanism(s) involved in the hepatic uptake of MPP⁺ remains partially unknown. The aim of the present study was to further characterize the hepatic uptake of ³H-MPP⁺, namely by investigating the interactions of catecholamines (which are also efficiently taken up by rat hepatocytes) with MPP¹ transport.The accumulation of ³H-MPP⁺ in isolated rat hepatocytes occurred through saturable and non-saturable mechanisms. The kinetics of the saturable component of ³H-MPP⁺ uptake was as follows: V_max = 181.3 ± 11.1 pmol mg protein^–1 min^–1 and K_m = 47.1 M (27.9, 66.3) (n = 5). The diffusion constant (in ml mg protein^–1 min^–1) for the non-saturable uptake of ³H-MPP⁺ was 0.00068 (0.00052, 0.00083) (n = 5). From the analysis of the time course of ³H-MPP⁺ accumulation at a substrate concentration of 100 nM ³H-MPP⁺, it was found that the rate constant of inward transport of ³H-MPP⁺ into hepatocytes (k_in) was 15.7 ± 3.8 l mg protein^–1 min^–1, the rate constant of outward transport of ³H-MPP⁺ from hepatocytes (k_out) was 0.077 ± 0.023 min^–1 and the equilibrium accumulation (A_max) of ³H-MPP⁺ was 20.2 ± 2.0 pmol mg protein^–1 (n = 36). Decynium22 (1,1-diethyl-2,2-cyanide; 1 M) significantly reduced k_in to 6.1 ± 1.8 l mg protein^–1 min^–1 (P < 0.05) and the equilibrium accumulation (A_max) of ³H-MPP⁺ to 9.6 ± 1.3 pmol mg protein^–1 (P < 0.005) (n = 36). ³H-MPP⁺ accumulation (in cells incubated with 200 nM ³H-MPP⁺) was sensitive to (–)-adrenaline, (–)-isoprenaline, (–)-dopamine, (±)-adrenaline and (–)-noradrenaline. The most potent catecholamine in inhibiting ³H-MPP⁺ uptake was (–)-adrenaline, with an IC₅₀ of 99 (22, 449) M (n = 6). (–)-Adrenaline competitively inhibited ³H-MPP⁺ uptake, as it significantly increased the K_m value of ³H-MPP⁺ uptake (to 125.4 M (63.6; 187.1); P < 0.02; n = 3) but did not change the V_max value. The cyanide-derivatives decynium22 and cyanine863 (1-ethyl-2-([1,4-dimethyl-2-phenyl-6-pyrimidinylidene]methyl)quinolinium), which inhibit uptake₂ as well as the apical type of the renal transporter for organic cations, potently inhibited ³H-MPP⁺ uptake with IC₅₀'s of 1.4 (0.4–5.3) (n = 6) and 6.5 (2.6–16) (n = 4) M, respectively. Under conditions of monoamine oxidase (MAO) and catechol-O-methyl transferase (COMT) inhibition with either pargyline (500 M + Ro01-2812) (3,5-dinitropyrocatechol; 2 M) or pargyline (500 M) + U-0521(3,4-dihidroxy-2-methyl-propiophenone; l2 M)), (–)-adrenaline (up to 1 mM) had no inhibitory effect on the uptake of ³H-MPP⁺. Moreover, the uptake of ³H-MPP⁺ in the presence of pargyline + Ro 01-2812 was significantly lower (66.9 ± 30.4%; P < 0.05; n = 4) than in the absence of these compounds. Therefore, the effect of these MAO and COMT inhibitors on ³H-MPP⁺ uptake was examined. Interestingly enough, pargyline, Ro 01-2812 and U-0521 were found to inhibit the uptake of ³H-MPP⁺ (in cells incubated with 200 nM ³H-MPP⁺): 500 M pargyline, 2 M Ro 012812 and 100 M U-0521 decreased the accumulation of ³H-MPP⁺ to 38.1 ± 6.8 (n = 5), 60.5 ± 10.1(n = 7) and 71.3 ± 14.5 (n = 7) % of control, respectively.It is concluded that ³H-MPP⁺ is efficiently taken up by rat hepatocytes by a carrier-mediated mechanism sensitive to catecholamines, decynium22 and cy anine863, and to the enzyme inhibitors pargyline, Ro 01-2812 and U-0521.