Nitric oxide synthase contributes to the maintenance of LTP in the oxytocin-mRFP1 neuron of the rat hypothalamus.

Oxytocin (OXT) is a neuropeptide hormone that plays a critical role in nociception. Long-term potentiation (LTP) is a major form of synaptic plasticity in the central nervous system. Recently, LTP has been reported in the hypothalamus; however, data on LTP in hypothalamic OXT-ergic neurons are unclear. Furthermore, the signaling pathways for hypothalamic OXT-ergic neuronal LTP and its physiological significance remain unknown. Herein, we aimed to investigate the induction of hypothalamic OXT-ergic neuronal LTP and its synaptic mechanism using OXT-monomeric red fluorescent protein 1 transgenic rats to visualize and record from OXT-ergic neurons. The hypothalamic paraventricular nucleus (PVN) OXT-ergic neuronal LTP induced by the pairing protocol was dependent on N-methyl-D-aspartate receptor (NMDAR). Furthermore, nitric oxide synthase (NOS) is required to maintain the LTP regardless of the NMDARs. In addition, hypothalamic OXT-ergic neuronal LTP was not induced in the adjuvant arthritis rat model but increased excitatory postsynaptic currents were detected. LTP in hypothalamic OXT-ergic neurons in the PVN in the presence of NOS may be involved in neuronal changes during OXT synthesis in chronic inflammation.

Chemogenetic Activation of Oxytocin Neurons Improves Pain in a Reserpine-induced Fibromyalgia Rat Model.

Fibromyalgia (FM) is a syndrome characterized by chronic pain with depression as a frequent comorbidity. However, efficient management of the pain and depressive symptoms of FM is lacking. Given that endogenous oxytocin (OXT) contributes to the regulation of pain and depressive disorders, herein, we investigated the role of OXT in an experimental reserpine-induced FM model. In FM model, OXT-monomeric red fluorescent protein 1 (OXT-mRFP1) transgenic rats exhibited increased depressive behavior and sensitivity in a mechanical nociceptive test, suggesting reduced pain tolerance. Additionally, the development of the FM-like phenotype in OXT-mRFP1 FM model rats was accompanied by a significant reduction in OXT mRNA expression in the magnocellular neurons of the paraventricular nucleus. OXT-mRFP1 FM model rats also had significantly fewer tryptophan hydroxylase (TPH)- and tyrosine hydroxylase (TH)-immunoreactive (ir) neurons as well as reduced serotonin and norepinephrine levels in the dorsal raphe and locus coeruleus. To investigate the effects of stimulating the endogenous OXT pathway, rats expressing OXT-human muscarinic acetylcholine receptor (hM3Dq)-mCherry designer receptors exclusively activated by designer drugs (DREADDs) were also assessed in the FM model. Treatment of these rats with clozapine-N-oxide (CNO), an hM3Dq-activating drug, significantly improved characteristic FM model-induced pathophysiological pain, but did not alter depressive-like behavior. The chemogenetically induced effects were reversed by pre-treatment with an OXT receptor antagonist, confirming the specificity of action via the OXT pathway. These results indicate that endogenous OXT may have analgesic effects in FM, and could be a potential target for effective pain management strategies for this disorder.

Validity and application of Doiguchi's pelvic tilt measurement method.

BACKGROUND: The validity of Doiguchi's pelvic tilt measurement method has not been proven. The objective in our study was to validate the method. METHODS: Our investigation included 73 total hip arthroplasties (THAs) performed using our cup placement procedure from July 2020 to November 2021. Pelvic tilt formed by the pubic symphysis and sacral promontory (PTPS) in supine and lateral positions was calculated by two methods (the Doiguchi method and the digital reconstructed radiograph (DRR) method using a 3D computer templating system) based on the transverse and longitudinal diameters of the pelvic ring measured immediately before THA. RESULTS: There was a strong/moderate correlation in the values of PTPS between the Doiguchi and DRR methods. However, the value of PTPS calculated by the Doiguchi method was significantly lower than that calculated by DRR, and there was a partially direct match. On the other hand, there was no significant difference in the value of PT change from supine to lateral position between the Doiguchi and DRR methods. The PT changes based on both methods were strongly correlated, and the PT change calculated by the Doiguchi method was almost identical to that calculated by the DRR method. CONCLUSIONS: Doiguchi's pelvic tilt measurement method was validated for the first time. These results demonstrated that the ratio of the transverse and longitudinal diameters of the pelvic ring was an important factor defining the change in pelvic tilt. The slope in the linear function of the Doiguchi method was found to be almost the correct value, although the intercept of the linear function exhibited individual differences.

Upregulation of the hypothalamo-neurohypophysial system and activation of vasopressin neurones attenuates hyperalgesia in a neuropathic pain model rat.

Arginine vasopressin (AVP) is a hypothalamic neurosecretory hormone well known as an antidiuretic, and recently reported to be involved in pain modulation. The expression kinetics of AVP and its potential involvement in the descending pain modulation system (DPMS) in neuropathic pain (NP) remains unclear. We investigated AVP expression and its effects on mechanical and thermal nociceptive thresholds using a unilateral spinal nerve ligation (SNL) model. All rats with SNL developed NP. Intensities of enhanced green fluorescent protein (eGFP) in the supraoptic and paraventricular nuclei, median eminence, and posterior pituitary were significantly increased at 7 and 14 days post-SNL in AVP-eGFP rats. In situ hybridisation histochemistry revealed significantly increased AVP mRNA expression at 14 days post-SNL compared with the sham control group. The chemogenetic activation of AVP neurones significantly attenuated mechanical and thermal hyperalgesia with elevated plasma AVP concentration. These analgesic effects were suppressed by pre-administration with V1a receptor antagonist. AVP neurones increased the neuronal activity of serotonergic dorsal raphe, noradrenergic locus coeruleus, and inhibitory interneurones in the spinal dorsal horn. These results suggest that the hypothalamo-neurohypophysial system of AVP is upregulated in NP and activated endogenous AVP exerts analgesic effects via the V1a receptors. AVP neurones may activate the DPMS.

Accurate cup placement using a portable navigation system during total hip arthroplasty based on pelvic orientation in the lateral decubitus position.

BACKGROUND: We previously proposed an accurate cup placement procedure using a portable navigation system (PNS) for total hip arthroplasty (THA) in the lateral decubitus position; however, the accuracy of our proposed procedure has not been shown, the aim of this study was to demonstrate the accuracy. METHODS: We prospectively analyzed 79 hips treated with primary THA; 40 hips treated until June 2020 were included in the conventional procedure (CP) group, and 39 hips treated from July 2020 were included in the modified procedure (MP) group. In the MP, pelvic orientation is considered to be the set coordinate axes in addition to the CP using the PNS. The accuracy was based on the difference between the navigation record (NR) and postoperative computed tomography measurement. RESULTS: The radiographic inclination (RI) and anteversion (RA) accuracies were 1.55° and 2.14°, respectively, in the MP group and 3.03° and 6.20°, respectively, in the CP group (p < 0.001). The error was within 5° of the NR for both the RI and RA in 34 in the MP group (87.2%) and 14 in the CP group (35.0%) (p < 0.001). The error was within 5° of the target angle (RI 40°, RA 15°) for both the RI and RA in 29 hips in the MP group (74.7%) and 12 in the CP group (30.0%) (p < 0.001). CONCLUSIONS: Our procedure with the consideration of pelvic orientation achieved dramatically improved the accuracy of PNS and was suitable to facilitate accurate cup placement.

Component gap control during posterior-stabilised total knee arthroplasty using the posterior condylar pre-cut technique.

PURPOSE: Adjusting the gap lengths to ensure equal lengths in both extension and flexion during total knee arthroplasty (TKA) is important for achieving successful outcomes. We designed a new pre-cut trial component (PCT) for posterior-stabilised (PS) TKA and aimed to determine whether the pre-cut technique is useful for component gap (CG) control in PS TKA. METHODS: A total of 70 knees were included. The PS PCT for PS TKA is composed of a 9-mm-thick distal part and 5-mm-thick posterior part with a cam structure. First, the distal femur and proximal tibia were cut to create an extension gap. Next, a 4-mm pre-cut was made from the posterior femoral condylar line; then, the PS PCT was attached, and the CGs were checked and compared at 0° and 90° knee flexion. Final CGs with the trial femoral components were compared with gaps in PS PCT at 0° and 90° knee flexion. RESULTS: CGs using PS PCTs were 10.2 mm at 0° and 13.6 mm at 90° knee flexion. According to the release of the posterior capsule at intercondylar notch and the adjustment of the cutting level of posterior femoral condyle, the final CG on knee extension was 11.3 mm; it did not significantly differ from CGs with PS PCT. The final CG at 90° knee flexion was 12.7 mm; it did not significantly differ from the estimated gap (12.4 mm) in PS PCT after flexion gap control. CONCLUSION: CG control using PS PCT is a useful technique during PS TKA. LEVEL OF EVIDENCE: Level IV: Case series.

Proposal of accurate cup placement procedure during total hip arthroplasty based on pelvic tilt discrepancies in the lateral position.

By combining the anatomical-pelvic-plane (APP) positioner with a newly improved navigation system during total hip arthroplasty (THA), it is theoretically possible to determine cup orientation based on the APP while tracking pelvic movement. The purpose of this study was to determine the navigation accuracy and whether the error is related to the pelvic position fixed by the positioner. Fifty hips that underwent primary THA between 2018 and 2020 were analysed. The accuracy was 2.34° at radiographic inclination (RI) and - 5.01° at radiographic anteversion (RA), and the error was within 10° at both RI and RA in only 40 of 50 hips (80.0%). The discrepancy in pelvic sagittal tilt was correlated with the cup orientation error and especially strongly correlated with the RA error (r = - 0.751, p < 0.001). When RI and RA were calculated using a correction formula to determine the true cup orientation based on the pelvic tilt discrepancies, the error in both RI and RA was within 10° in all cases (100%). The navigation accuracy is related to the pelvic position fixed by the positioner, and the correction formula for the target angle that considers pelvic tilt discrepancies can lead to accurate cup placement in the future.

Heat hypersensitivity is attenuated with altered expression level of spinal astrocytes after sciatic nerve injury in TRPV1 knockout mice.

Transient receptor potential vanilloid 1 (TRPV1) modulates pain. Studies have indicated that TRPV1 is upregulated in the spinal dorsal horn in the neuropathic pain model, but its mechanism is unknown. Here, we examined the mechanism by which TRPV1 modulates neuropathic pain by employing partial sciatic nerve ligation (pSNL) in adult male C57BL/6 J (wild-type: WT) and TRPV1 knockout (Trpv1-/-) mice. We analyzed mechanical/heat sensitivities (von Frey test/hot plate test) and glial/neuronal activities (Iba-1/GFAP/FosB by immunofluorescence) in laminae I and II in the L5 ipsilateral dorsal horn of the spinal cord. Mechanical/heat sensitivities, expression levels of microglial Iba-1 and astrocytic GFAP, and the number of FosB-positive neurons were significantly increased on days 7 and 14 in the pSNL group compared with the sham-operated and non-operated groups of both WT and Trpv1-/- mice. While mechanical sensitivity was comparable between WT and Trpv1-/- mice, the threshold against heat sensitivity was markedly prolonged in Trpv1-/- than WT mice on day 14 after pSNL. Conversely, the increment of FosB positive neurons was significantly attenuated in Trpv1-/- than WT mice on days 7 and 14 after pSNL. These results suggest that TRPV1 may modulate thermal perception via increased astrocytes in the dorsal horn of the spinal cord.

Factors associated with mortality among patients with necrotizing soft tissue infections: An analysis of 4597 cases using the Diagnosis Procedure Combination Database.

OBJECTIVE: This study aimed to determine the factors associated with mortality among patients with necrotizing soft tissue infection (NSTI) in Japan using inpatient data from the Diagnosis Procedure Combination (DPC) Database. METHODS: We conducted a cross-sectional study using a population retrieved from the Japanese DPC inpatient database of patients who underwent surgical operations from 2014 through 2017. The associations between the covariates and mortality were estimated using multivariate logistic regression models. RESULTS: In total, 4597 patients were registered in this study, with an overall mortality rate of 6.9%. Multilevel logistic regression analysis revealed that higher age, lower body mass index (BMI < 18.5 kg/m2), pre-existing cancer diagnosis, sepsis at admission, maintenance dialysis, antithrombin III use, and anti-methicillin-resistant Staphylococcus aureus (MRSA) antibiotic use were associated with a high mortality rate among NSTI patients. However, sex, underlying diabetes mellitus, ambulance use at admission, intravenous immunoglobulin use, higher hospital case volume, and frequency of operations were not associated with mortality. CONCLUSION: This study is the first to report the association of lower BMI, antithrombin III use, and anti-MRSA antibiotic use with a higher mortality rate among NSTI patients.

The neurohypophysial oxytocin and arginine vasopressin system is activated in a knee osteoarthritis rat model.

Osteoarthritis (OA) causes chronic joint pain and significantly impacts daily activities. Hence, developing novel treatment options for OA has become an increasingly important area of research. Recently, studies have reported that exogenous, as well as endogenous, hypothalamic-neurohypophysial hormones, oxytocin (OXT) and arginine-vasopressin (AVP), significantly contribute to nociception modulation. Moreover, the parvocellular OXT neurone (parvOXT) extends its projection to the superficial spinal dorsal horn, where it controls the transmission of nociceptive signals. Meanwhile, AVP produced in the magnocellular AVP neurone (magnAVP) is released into the systemic circulation where it contributes to pain management at peripheral sites. The parvocellular AVP neurone (parvAVP), as well as corticotrophin-releasing hormone (CRH), suppresses inflammation via activation of the hypothalamic-pituitary adrenal (HPA) axis. Previously, we confirmed that the OXT/AVP system is activated in rat models of pain. However, the roles of endogenous hypothalamic-neurohypophysial hormones in OA have not yet been characterised. In the present study, we investigated whether the OXT/AVP system is activated in a knee OA rat model. Our results show that putative parvOXT is activated and the amount of OXT-monomeric red fluorescent protein 1 positive granules in the ipsilateral superficial spinal dorsal horn increases in the knee OA rat. Furthermore, both magnAVP and parvAVP are activated, concurrent with HPA axis activation, predominantly modulated by AVP, and not CRH. The OXT/AVP system in OA rats was similar to that in systemic inflammation models, including adjuvant arthritis; however, magnocellular OXT neurones (magnOXT) were not activated in OA. Hence, localised chronic pain conditions, such as knee OA, activate the OXT/AVP system without impacting magnOXT.

Presynaptic glutamatergic transmission and feedback system of oxytocinergic neurons in the hypothalamus of a rat model of adjuvant arthritis.

The neurohypophysial hormone oxytocin (OXT) is synthesized in the hypothalamic paraventricular and supraoptic nuclei. Recently, some studies have considered OXT to be important in sensory modulation and that the OXT protein is upregulated by acute and chronic nociception. However, the mechanism by which OXT is upregulated in neurons is unknown. In this study, we examined the resting membrane potentials and excitatory postsynaptic currents in OXT-ergic neurons in the paraventricular nucleus in adjuvant arthritis rat model, a model of chronic inflammation, using whole-cell patch-clamping. Transgenic rats expressing OXT and monomeric red fluorescent protein 1 (mRFP1) fusion protein to visualize the OXT-ergic neurons were used, and the OXT-mRFP1 transgenic rat model of adjuvant arthritis was developed by injection of heat-killed Mycobacterium butyricum. Furthermore, the feedback system of synthesized OXT was also examined using the OXT receptor antagonist L-368,899. We found that the resting membrane potentials and frequency of miniature excitatory postsynaptic currents and spontaneous excitatory postsynaptic currents in OXT-monomeric red fluorescent protein 1 neurons in the paraventricular nucleus were significantly increased in adjuvant arthritis rats. Furthermore, L-368,899 dose-dependently increased the frequency of miniature excitatory postsynaptic currents and spontaneous excitatory postsynaptic currents in OXT-ergic neurons. Following bath application of the GABAA receptor antagonist picrotoxin and the cannabinoid receptor 1 antagonist AM 251, L-368,899 still increased the frequency of miniature excitatory postsynaptic currents. However, following bath application of the nitric oxide synthase inhibitor Nω-Nitro-L-arginine methyl ester hydrochloride, L-368,899 did not alter the miniature excitatory postsynaptic current frequency. Thus, it is suggested that OXT-ergic neuron activity is upregulated via an increase in glutamate release, and that the upregulated OXT neurons have a feedback system with released endogenous OXT. It is possible that nitric oxide, but not GABA, may contribute to the feedback system of OXT neurons in chronic inflammation.

Transient receptor potential vanilloid 1 and 4 double knockout leads to increased bone mass in mice.

Calcium balance is important in bone homeostasis. The transient receptor potential vanilloid (TRPV) channel is a nonselective cation channel permeable to calcium and is activated by various physiological and pharmacological stimuli. TRPV1 and TRPV4, in particular, have important roles in intracellular Ca2+ signaling and extracellular calcium homeostasis in bone cells. TRPV1 and TRPV4 separately mediate osteoclast and osteoblast differentiation, and deficiency in any of these channels leads to increased bone mass. However, it remains unknown whether bone mass increases in the absence of both TRPV1 and TRPV4. In this study, we used TRPV1 and TRPV4 double knockout (DKO) mice to evaluate their bone mass in vivo, and osteoclast and osteoblast differentiation in vitro. Our results showed that DKO mice and wild type (WT) mice had no significant difference in body weight and femur length. However, the results of dual-energy X-ray absorption, microcomputed tomography, and bone histomorphometry clearly showed that DKO mice had higher bone mass than WT mice. Furthermore, DKO mice had less multinucleated osteoclasts and had lower bone resorption. In addition, the results of cell culture using flushed bone marrow from mouse femurs and tibias showed that osteoclast differentiation was suppressed, whereas osteoblast differentiation was promoted in DKO mice. In conclusion, our results suggest that the increase in bone mass in DKO mice was induced not only by the suppression of osteoclast differentiation and activity but also by the augmentation of osteoblast differentiation and activity. Our findings reveal that both the single deficiency of TRPVs and the concurrent deficiency of TRPVs result in an increase in bone mass. Furthermore, our data showed that DKO mice and single KO mice had varying approaches to osteoclast and osteoblast differentiation in vitro, and therefore, it is important to conduct further studies on TRPVs regarding the increase in bone mass to explore not only individual but also a combination of TRPVs.

Acute Mono-Arthritis Activates the Neurohypophysial System and Hypothalamo-Pituitary Adrenal Axis in Rats.

Various types of acute/chronic nociceptive stimuli cause neuroendocrine responses such as activation of the hypothalamo-neurohypophysial [oxytocin (OXT) and arginine vasopressin (AVP)] system and hypothalamo-pituitary adrenal (HPA) axis. Chronic multiple-arthritis activates the OXT/AVP system, but the effects of acute mono-arthritis on the OXT/AVP system in the same animals has not been simultaneously evaluated. Further, AVP, not corticotropin-releasing hormone (CRH), predominantly activates the HPA axis in chronic multiple-arthritis, but the participation of AVP in HPA axis activation in acute mono-arthritis remains unknown. Therefore, we aimed to simultaneously evaluate the effects of acute mono-arthritis on the activity of the OXT/AVP system and the HPA axis. In the present study, we used an acute mono-arthritic model induced by intra-articular injection of carrageenan in a single knee joint of adult male Wistar rats. Acute mono-arthritis was confirmed by a significant increase in knee diameter in the carrageenan-injected knee and a significant decrease in the mechanical nociceptive threshold in the ipsilateral hind paw. Immunohistochemical analysis revealed that the number of Fos-immunoreactive (ir) cells in the ipsilateral lamina I-II of the dorsal horn was significantly increased, and the percentage of OXT-ir and AVP-ir neurons expressing Fos-ir in both sides of the supraoptic (SON) and paraventricular nuclei (PVN) was increased in acute mono-arthritic rats. in situ hybridization histochemistry revealed that levels of OXT mRNA and AVP hnRNA in the SON and PVN, CRH mRNA in the PVN, and proopiomelanocortin mRNA in the anterior pituitary were also significantly increased in acute mono-arthritic rats. Further, plasma OXT, AVP, and corticosterone levels were significantly increased in acute mono-arthritic rats. These results suggest that acute mono-arthritis activates ipsilateral nociceptive afferent pathways at the spinal level and causes simultaneous and integrative activation of the OXT/AVP system. In addition, the HPA axis is activated by both AVP and CRH in acute mono-arthritis with a distinct pattern compared to that in chronic multiple-arthritis.

Negative Pressure Wound Therapy with Surgical Gloves to Repair Soft Tissue Defects in Hands.

The efficacy of negative pressure wound therapy (NPWT) in the treatment of skin defect wounds has been established, but it is difficult to apply to hand surgery because of the easy occurrence of air leaks. We report two cases of performing NPWT with surgical gloves. Case1: A 37-year-old male was injured on his right dorsal hand from a punch. He presented to our hospital three days after the injury because of swelling and pain. The wound was infected and contused, so wound lavage and debridement (W&D) were performed under local anesthesia. The infected condition didn't improve after antimicrobial infusion, so W&D were performed again 8 days after the first visit. Then W&D were performed every day, and the infection subsided 15 days after the first visit. NPWT was initiated for the purpose of managing exudate and the wound condition, and healthy granulation tissue formed gradually. Finally, transpositional flap and full-thickness skin graft were performed on day 29. Case2: A 43-year-old male accidentally sustained a high pressure injection of oil into his dorsal hand. He presented to our hospital the next day, and W&D were performed. W&D were performed again two days after the first visit, and artificial dermis was applied over a part of the wound that was impossible to close. A decision was made to apply NPWT and a surgical glove for the purpose of reducing swelling and managing wound exudate. The swelling decreased and granulation tissue formed gradually, then nine days after the first visit a sural nerve graft was applied to bridge the defective area, and a full thickness skin graft was applied. We achieved good wound closure and hand function recovery after using NPWT and a surgical glove.