Tetherless Optical Neuromodulation: Wavelength from Orange-red to Mid-infrared

Optogenetics, a technique that employs light for neuromodulation, has revolutionized the study of neural mechanisms and the treatment of neurological disorders due to its high spatiotemporal resolution and cell-type specificity. However, visible light, particularly blue and green light, commonly used in conventional optogenetics, has limited penetration in biological tissue. This limitation necessitates the implantation of optical fibers for light delivery, especially in deep brain regions, leading to tissue damage and experimental constraints. To overcome these challenges, the use of orange-red and infrared light with greater tissue penetration has emerged as a promising approach for tetherless optical neuromodulation. In this review, we provide an overview of the development and applications of tetherless optical neuromodulation methods with long wavelengths. We first discuss the exploration of orange-red wavelength-responsive rhodopsins and their performance in tetherless optical neuromodulation. Then, we summarize two novel tetherless neuromodulation methods using near-infrared light: upconversion nanoparticle-mediated optogenetics and photothermal neuromodulation. In addition, we discuss recent advances in mid-infrared optical neuromodulation.

A role of prefrontal cortico-hypothalamic projections in wake promotion

Ventromedial prefrontal cortex (vmPFC) processes many critical brain functions, such as decision-making, value-coding, thinking, and emotional arousal/recognition, but whether vmPFC plays a role in sleep-wake promotion circuitry is still unclear. Here, we find that photoactivation of dorsomedial hypothalamus (DMH)-projecting vmPFC neurons, their terminals, or their postsynaptic DMH neurons rapidly switches non-rapid eye movement (NREM) but not rapid eye movement sleep to wakefulness, which is blocked by photoinhibition of DMH outputs in lateral hypothalamus (LHs). Chemoactivation of DMH glutamatergic but not GABAergic neurons innervated by vmPFC promotes wakefulness and suppresses NREM sleep, whereas chemoinhibition of vmPFC projections in DMH produces opposite effects. DMH-projecting vmPFC neurons are inhibited during NREM sleep and activated during wakefulness. Thus, vmPFC neurons innervating DMH likely represent the first identified set of cerebral cortical neurons for promotion of physiological wakefulness and suppression of NREM sleep.

Brachial plexus avulsion induced changes in gut microbiota promotes pain related anxiety-like behavior in mice

Introduction

Brachial plexus avulsion (BPA) injury develops frequent and intense neuropathic pain, involving in both peripheral and central nervous systems. The incidence of anxiety or depression caused by BPA-induced neuropathic pain is high, but the underlying mechanism remains unclear.

Methods

We established a BPA mice model and assessed its negative emotions through behavioral tests. To further explore the role of the microbiota-gut-brain axis in the unique emotional behavior after BPA, we performed intestinal fecal 16s and metabolomics assays. Psychobiotics (PB) supplementation was administered to BPA mice to check the probiotics effects on BPA-induced anxiety behaviors.

Results

Pain related anxiety-like behavior was observed at the early stage after BPA (7 days), while no depression-like behavior was detected. Intriguingly, gut microbiota diversity was increased in BPA mice, and the most abundant probiotics, Lactobacillus, showed obvious changes. Lactobacillus_reuteri was significantly decreased in BPA mice. Metabolomics analysis showed that Lactobacillus_reuteri-related bile acid pathway and some neurotransmitter amino acids were significantly altered. Further PB (dominated by Lactobacillus_reuteri) supplementation could significantly relieve BPA-induced anxiety-like behaviors in mice.

Conclusion

Our study suggests that pathological neuralgia after BPA could alter intestinal microbiota diversity, especially Lactobacillus, and the changes in neurotransmitter amino acid metabolites may be the key reason for the onset of anxiety-like behaviors in BPA mice.

Melatonin pretreatment alleviates the long-term synaptic toxicity and dysmyelination induced by neonatal Sevoflurane exposure via MT1 receptor-mediated Wnt signaling modulation

Sevoflurane (Sev) is one of the most widely used pediatric anesthetics. The major concern of neonatal repeated application of Sev is its potential long-term impairment of cognition and learning/memory, for which there still lacks effective treatment. At the cellular level, Sev exerts toxic effects in multiple aspects, making it difficult for effective interference. Melatonin is a pineal hormone regulated by and feedbacks to biological rhythm at physiological condition. Recent studies have revealed significant neuroprotective effects of exogenous melatonin or its agonists under various pathological conditions. Whether melatonin could prevent the long-term toxicity of Sev remains elusive. Here, we report that neonatal repeated Sev exposure up-regulated MT1 receptor in hippocampal neurons and oligodendrocytes. Pretreatment with melatonin significantly alleviated Sev-induced synaptic deficiency, dysmyelination, and long-term learning impairment. Both MT1-shRNA and MT1 knockout effectively blocked the protective effects of melatonin on synaptic development, myelination, and behavior performance. Interestingly, long-lasting suppression of Wnt signaling, instead of cAMP/PKA signaling, was observed in hippocampal neurons and oligodendrocytes after neonatal Sev exposure. Pharmacologically activating Wnt signaling rescued both the long-term synaptic deficits and dysmyelination induced by Sev. Further analysis showed that MT1 receptor co-expressed well with β-catenin and Axin2 and bound to β-catenin by its C-terminal. Melatonin pretreatment effectively rescued Sev-induced Wnt suppression. Wnt signaling inhibitor XAV939 significantly compromised the protective effects of melatonin. Taken together, our data demonstrated a beneficial effect of melatonin pretreatment on the long-term synaptic impairment and dysmyelination induced by neonatal Sev exposure, and a novel MT1 receptor-mediated interaction between melatonin and canonical Wnt signaling, indicating that melatonin may be clinically applied for improving the safety of pediatric Sev anesthesia.

[Feasibility, efficacy and safety of transbrachial access for interventional therapy on paravalvular leak post surgical valve replacement]

Objective: To investigate the feasibility, efficacy and safety of transbrachial access for interventional therapy on prosthetic paravalvular leak (PVL) post surgical valve replacement. Methods: This is a retrospective study. Patients with PVL after surgical valve replacement who underwent interventional therapy via the brachial artery approach in Structural heart disease center of Fuwai hospital between August 2017 and October 2019, were included. All patients underwent puncture of the brachial artery under local anesthesia, angiography and transcatheter closure procedure were performed. The procedure was performed under transthoracic echocardiography (TTE) guidance. Baseline data, operation data and pre-and post-operative TTE examination results were collected and analyzed. Postoperative complications were recorded and operational adverse events were obtained during follow up in the outpatient department after discharge. The operation success rate was calculated, which was defined as the degree of perivalvular regurgitation decrease by 1 grade and above according to TTE without interfering the valve movement and coronary artery blood flow within 30 days after occluder placement. Results: A total of 10 patients were enrolled in this study, the mean age was (57.5±14.6) years, and 6 patients were males. There were 7 cases with aortic PVL, and 3 cases with mitral PVL. Except for one patient who was converted to the femoral vein-transseptal approach, the other 9 patients were successfully implanted with the devices via the brachial artery approach. The operation time was (103.3±34.0) minutes, and there was no need for rigorous bed rest after the operation. The median hospital stay was 7.5 (3.0, 9.8) days. The operation success rate was 9/10 via the brachial artery approach. The differences in the degree of perivalvular regurgitation, New York Heart Association (NYHA) classification, left ventricular end diastolic diameter and left atrial diameter before and after operation were statistically significant (all P<0.05). One case developed new hemolysis with renal insufficiency on the second day after procedure and discharged after successful dialysis. Another case experienced complication of brachial artery pseudoaneurysm after procedure and discharged after successful treatment with thrombin injection. The mean follow-up time was (14.3±7.9) months. During the follow-up, NYHA classification remained as Ⅰ/Ⅱ in 9 patients, no operational adverse events were observed. Conclusions: Transbrachial access for interventional therapy on PVL post surgical valve replacement is a feasible, effective, and safe procedure. It has the advantages of simplifying the operation process and reducing postoperative bed rest time.

LF-rTMS ameliorates social dysfunction of FMR1-/- mice via modulating Akt/GSK-3β signaling

Autism spectrum disorders (ASD) are a group of neurological disorders which affect approximately 1% of children around the world. Social dysfunction is one of the two core syndromes of ASD, and still lacks effective treatment. Transcranial magnetic stimulation (TMS) is a noninvasive and safe procedure that uses magnetic fields to modulate neural activity. Whether it were effective in modulating social function remains unclear. By using 3-chamber test, ultrasonic vocalization recording and Western-blotting, we demonstrated that FMR1 (fragile X mental retardation protein) mutant mice, a model of ASD, exhibited obvious defects in social preference and ultrasonic communication. In addition, we detected increase of p-Akt (S473) and p-GSK-3β (S9), and decrease of p-PSD-95 (T19) in the anterior cingulate cortex (ACC) of FMR1^-/- mice. Treating FMR1^-/- mice with 1 Hz repetitive TMS (rTMS) exerted a long lasting effect in improving both the ultrasonic communication and social preference, as well as restoring the levels of Akt/GSK-3β activity and spine density in the FMR1^-/-ACC. Our data, for the first time, demonstrated a beneficial effect of low frequency rTMS (LF-rTMS) on the social function of FMR1^-/- mice and an involvement of Akt/GSK-3β signaling in this process, indicating LF-rTMS as a potential therapeutic strategy for ASD patients.

Estrogen enhances the proliferation and migration of ovarian cancer cells by activating transient receptor potential channel C3

Background

Recent studies have suggested that estrogen (E2) plays an important role in epithelial ovarian cancer (EOC). However, the mechanism of E2 in ovarian cancers is unclear. The purpose of this study was to investigate the effect of E2 on ovarian cancers and illuminate the mechanism of E2 in promote ovarian cancers proliferation.

Results

We demonstrated that E2 stimulated the proliferation and invasion of ovarian cancer cells. In this study, ovarian cancer specimens were also analyzed for transient receptor potential channel C3 (TRPC3) expression; TRPC3 expression levels were higher in ovarian cancer samples than in normal ovarian tissue samples. Previous studies have shown that TRPC3 contributes to the progression of human ovarian cancer. In this study, we further investigated the interaction between E2 and TRPC3. We found that E2 stimulation enhanced the expression of TRPC3 at both the mRNA and protein levels. E2 stimulation enhanced the influx of Ca2⁺. Moreover, siRNA-mediated silencing of TRPC3 expression inhibited the ability of E2 to stimulate the influx of Ca2⁺.

Conclusions

In conclusion, TRPC3 plays a significant role in the stimulatory activity of E2 and could be a therapeutic target for the treatment of EOC. Furthermore, this study elucidates the molecular mechanism by which E2 promotes the proliferation and migration of EOC cells.

Involvement of homodomain interacting protein kinase 2-c-Jun N-terminal kinase/c-Jun cascade in the long-term synaptic toxicity and cognition impairment induced by neonatal Sevoflurane exposure

Sevoflurane is one of the most widely used anesthetics with recent concerns rising about its pediatric application. The synaptic toxicity and mechanisms underlying its long‐term cognition impairment remain unclear. In this study, we investigated the expression and roles of homeodomain interacting protein kinase 2 (HIPK2), a stress activating kinase involved in neuronal survival and synaptic plasticity, and its downstream c‐Jun N‐terminal kinase (JNK)/c‐Jun signaling in the long‐term toxicity of neonatal Sevoflurane exposure. Our data showed that neonatal Sevoflurane exposure results in impairment of memory, enhancement of anxiety, less number of excitatory synapses and lower levels of synaptic proteins in the hippocampus of adult rats without significant changes of hippocampal neuron numbers. Up‐regulation of HIPK2 and JNK/c‐Jun was observed in hippocampal granular neurons shortly after Sevoflurane exposure and persisted to adult. 5‐((6‐Oxo‐5‐(6‐(piperazin‐1‐yl)pyridin‐3‐yl)‐1,6‐dihydropyridin‐3‐yl)methylene)thiazolidine‐2,4‐dione trifluoroacetate, antagonist of HIPK2, could significantly rescue the cognition impairment, decrease in long‐term potentiation, reduction in spine density and activation of JNK/c‐Jun induced by Sevoflurane. JNK antagonist SP600125 partially restored synapse development and cognitive function without affecting the expression of HIPK2. These data, in together, revealed a novel role of HIPK2‐JNK/c‐Jun signaling in the long‐term synaptic toxicity and cognition impairment of neonatal Sevoflurane exposure, indicating HIPK2‐JNK/c‐Jun cascade as a potential target for reducing the synaptic toxicity of Sevoflurane.

Cover Image for this issue: doi: 10.1111/jnc.14757.

Single-Cell Analysis for Glycogen Localization and Metabolism in Cultured Astrocytes

Cerebral glycogen is principally localized in astrocytes rather than in neurons. Glycogen metabolism has been implicated in higher brain functions, including learning and memory, yet the distribution patterns of glycogen in different types of astrocytes have not been fully described. Here, we applied a method based on the incorporation of 2-NBDG, a d-glucose fluorescent derivative that can trace glycogen, to investigate glycogen’s distribution in the brain. We identified two types of astrocytes, namely, 2-NBDG^I (glycogen-deficient) and 2-NBDG^II (glycogen-rich) cells. Whole-cell patch-clamp and fluorescence-activated cell sorting (FACS) were used to separate 2-NBDG^II astrocytes from 2-NBDG^I astrocytes. The expression levels of glycogen metabolic enzymes were analyzed in 2-NBDG^I and 2-NBDG^II astrocytes. We found unique glycogen metabolic patterns between 2-NBDG^I and 2-NBDG^II astrocytes. We also observed that 2-NBDG^II astrocytes were mainly identified as fibrous astrocytes but not protoplasmic astrocytes. Our data reveal cell type-dependent glycogen distribution and metabolism patterns, suggesting diverse functions of these different astrocytes.

Deficiency of tumor suppressor NDRG2 leads to attention deficit and hyperactive behavior

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent psychiatric disorder in children. Although an imbalance of excitatory and inhibitory inputs has been proposed as contributing to this disorder, the mechanisms underlying this highly heterogeneous disease remain largely unknown. Here, we show that N-myc downstream-regulated gene 2 (NDRG2) deficiency is involved in the development of ADHD in both mice and humans. Ndrg2-knockout (Ndrg2-/-) mice exhibited ADHD-like symptoms characterized by attention deficits, hyperactivity, impulsivity, and impaired memory. Furthermore, interstitial glutamate levels and excitatory transmission were markedly increased in the brains of Ndrg2-/- mice due to reduced astroglial glutamate clearance. We developed an NDRG2 peptide that rescued astroglial glutamate clearance and reduced excitatory glutamate transmission in NDRG2-deficient astrocytes. Additionally, NDRG2 peptide treatment rescued ADHD-like hyperactivity in the Ndrg2-/- mice, while routine methylphenidate treatment had no effect on hyperactivity in these animals. Finally, children who were heterozygous for rs1998848, a SNP in NDRG2, had a higher risk of ADHD than children who were homozygous for rs1998848. Our results indicate that NDRG2 deficiency leads to ADHD phenotypes and that impaired astroglial glutamate clearance, a mechanism distinct from the well-established dopamine deficit hypothesis for ADHD, underlies the resultant behavioral abnormalities.

In Vivo changes in the lengths of carpal ligaments after mild dorsal angulation of distal radius fractures

The need for surgical correction in patients with malunion with mild dorsal angulation after a distal radius fracture is controversial. We specifically investigated in vivo changes in the lengths of carpal ligaments in a group of patients with mild-degree dorsal angulation following a distal radial fracture. We obtained computed tomography scans of both wrists in eight patients, whose distal radius on one side had united with dorsal angulation from 10° to 20°. The three-dimensional images of the carpus were reconstructed and the lengths of wrist ligaments were measured based on known anatomical landmarks. Compared with the contralateral uninjured side, the dorsal radiocarpal ligament and ulnotriquetral ligament were substantially lengthened (p < 0.05) and the long radiolunate ligament was substantially shortened (p < 0.05) at most wrist positions except extension. However, five other ligaments that we measured did not show significant differences in length compared with those of the uninjured side (p > 0.05). The lengths of some ligaments are substantially altered even by mild dorsal angulation of the distal radius, while the lengths of most other ligaments are not substantially affected.

Krüppel-like factor 8 contributes to hypoxia-induced MDR in gastric cancer cells

We previously reported that hypoxia-induced MDR in gastric cancer (GC) cells is hypoxia-inducible factor-1 (HIF-1)-dependent. However, the exact mechanisms are still unknown. Our previous study revealed that Krüppel-like factor 8 (KLF8), a novel transcription factor, was associated with malignant phenotype in GC cells. KLF8 is overexpressed in clear cell renal carcinoma lacking von Hippel-Lindau protein function, which resulted in HIF-1 stabilization. Given this association, we hypothesized that KLF8 contributed to hypoxia-induced MDR in GC cells. Initial experiments revealed that hypoxia could increase KLF8 and HIF-1α expressions in GC cells, and KLF8 levels in GC drug-resistant cell lines were higher than in parental cell lines. Subsequent experiments showed that in normoxia, exogenous KLF8 could promote the MDR phenotype; however, blocking KLF8 expression could effectively reverse the MDR phenotype induced by hypoxia. Overexpressed KLF8 increased resistance-associated gene MDR1 mRNA levels, Bcl-2 and P-gp protein levels, and decreased Bax and caspase-3 protein levels in GC cells, and knockout KLF8 reversed these effects. Dual luciferase reporter and ChIP assays showed that KLF8 could promote MDR1 transcriptional activity by combining with KLF8 binding sites located in the upstream of MDR1 transcriptional start site. These results suggest that KLF8 is involved in hypoxia-induced MDR through inhibiting apoptosis and increasing the drug release rate by directly regulating MDR1 transcription.

This study aims to discuss whether KLF8 involves in hypoxia-induced multi-drug resistance and its mechanism. Our results showed that hypoxia could increase KLF8 expression in gastric cancer cells. Meanwhile, we found that KLF8 contributed to hypoxia-induced multi-drug resistance via regulating MDR1 directly. Through this research, we found a new target gene of KLF8 and further clarified the mechanism of multi-drug resistance happened in gastric cancer.

KLF8 involves in TGF-beta-induced EMT and promotes invasion and migration in gastric cancer cells

PURPOSE

Krüppel-like factor 8 (KLF8), a downstream transcription factor of transforming growth factor-β1 (TGF-β1), has a role in tumorigenesis, tumor progress and epithelial-to-mesenchymal transition (EMT) induction. Recent studies mainly focused on its role in breast cancer and hepatocellular carcinoma; however, little is studied in gastric cancer. Here, we aim to explore whether KLF8 is involved in TGF-β1-induced EMT in gastric cancer cells.

METHODS

Western blot and real-time PCR assays were used to detect the expression of KLF8, E-cadherin and vimentin in gastric cancer cell line SGC7901 treated with or without TGF-β1. The lentivirus-mediated RNA interference technique was used to knock down the expression of KLF8 in gastric cancer cell line SGC7901. In vitro, the ability of cell migration and invasion were measured by transwell and wound healing assays; the cell motility was detected by high content screening assay.

RESULTS

TGF-β1 could induce EMT via down-regulating E-cadherin and up-regulating vimentin expression in gastric cancer cells. Further study found that TGF-β1 could induce KLF8 expression at the protein and mRNA levels in gastric cancer cells (P < 0.05). Western blot and real-time PCR assays found that small interference RNA (siRNA)-mediated KLF8 silence blocked TGF-β1-induced EMT-like transformation and subsequently reversed the loss of E-cadherin and gain of vimentin. In vitro, inhibition of KLF8 decreased TGF-β1-prompted cell migration, invasion and motility.

CONCLUSIONS

KLF8, a transcription factor, is involved in TGF-β1-induced EMT in gastric cancer cells and may be a novel therapeutic target for the treatment of gastric cancer.

Digital oedema, adhesion formation and resistance to digital motion after primary flexor tendon repair

The development of digital oedema, adhesion formation, and resistance to digital motion at days 0, 3, 5, 7, 9 and 14 after primary flexor tendon repairs using 102 long toes of 51 Leghorn chickens was studied. Oedema presented as tissue swelling from days 3 to 7, which peaked at day 3. After day 7, oedema was manifest as hardening of subcutaneous tissue. The degree of digital swelling correlated with the resistance to tendon motion between days 3 and 7. At day 9, granulation tissues were observed around the tendon and loose adhesions were observed at day 14. Resistance to digital motion increased significantly from day 0 to day 3, but did not increase between days 3 and 9. The early postoperative changes appear to have three stages: initial (days 0-3, increasing resistance with development of oedema), delayed (days 4-7, higher resistance with continuing oedema) and late (after day 7-9, hardening of subcutaneous tissue with development of adhesions).

The gliding force and work of flexion in the early days after primary repair of lacerated flexor tendons: an experimental study

We measured the resistance to tendon mobilisation within the first 5 days after primary repair of digital flexor tendons of chickens. Forty-six long toes of 23 chickens were assigned to six surgical groups and one unoperated control group. The tendons were partially lacerated and surgically repaired. The resistance to simulated active digital flexion was assessed in six operated groups at 0, 1, 2, 3, 4 and 5 days postoperatively. The force of tendon motion and work of flexion increased gradually from day 0 to day 5. The force and work at days 4 and 5 were significantly higher than those at days 0 and 1. No statistical difference was found in the resistance at days 0, 1, 2 and 3. Our results indicate that the gliding resistance gradually increases over the first 5 days after surgery and suggest that tendon motion may be started after the first 3 days, to avoid moving during this period of increased resistance with increased risk of tendon rupture.

Biomechanical analysis of a modification of Tang method of tendon repair

We report a modification of the original Tang technique of tendon repair which uses fewer sutures and has fewer knots on the tendon surface. The modified method consists of six longitudinal and two horizontal strands that form an "M" configuration within the tendon and four dorsal longitudinal strands made with a single looped suture. Thirty-six fresh pig flexor tendons were divided and repaired with either the modified Tang or the Tang method. The tendons were subjected to linear or 90 degrees angular loading in an Instron tensile machine. The gap formation strength and ultimate strength of the modified Tang repair was statistically identical to those of the Tang method under linear tension. Under angular tension, the ultimate strength of the modified Tang method was greater than that of the Tang method.

Dorsal-enhanced sutures improve tension resistance of tendon repair

Thirty-six fresh pig flexor tendons were repaired using either the modified Kessler method or the Tang method. Nine tendons from each group were tested in an Instron tensile testing machine with the tendons passing 90 degrees around a pulley. The other nine tendons from each group were pulled linearly by the testing machine. The 2 mm gap formation force of the tendons repaired with the modified Kessler and Tang methods and pulled at 90 degrees were 64%+/-5% and 79%+/-9% respectively of those forces recorded during linear testing. The ultimate strengths of tendons repaired by the modified Kessler and Tang methods and pulled at 90 degrees were 76%+/-6% and 81%+/-8% respectively of the forces measured during linear testing. The percentage gap formation and ultimate strength of the Tang method was significantly higher than that of the modified Kessler suture when the tendons were pulled around a pulley. This demonstrates that the Tang suture, with its main components in the dorsal part of the repaired tendon, has greater tension resistance capacity than conventional tendon sutures which are placed in the middle of the tendon. This study suggests that dorsally-enhanced multiple tendon sutures are better placed to sustain the tension generated during active finger flexion.

Effects of tension direction on strength of tendon repair

We investigated changes of tensile strength in tendon repair according to tension direction. Thirty-six fresh-frozen digital flexor tendons were divided into 4 groups with 9 tendons each. The tendons were repaired by the modified Kessler method. Sutured tendons were pulled against pulleys at angles of 0 degrees, 30 degrees, 60 degrees, and 90 degrees to the direction of the pull of the testing machine in the 4 groups, respectively. The repaired tendons were tested in a tensile machine to determine 2-mm gap formation force and ultimate strength of the tendons. The 2-mm gap formation force and ultimate strength in the tendons pulled at 0 degrees were statistically higher than those in the tendons pulled at 30 degrees, 60 degrees, and 90 degrees. The 2-mm gap formation force of the tendons pulled at 30 degrees, 60 degrees, and 90 degrees was 86% +/- 10%, 73% +/- 9%, and 64% +/- 8% of that at 0 degrees, respectively. Ultimate strength of tendons pulled at 30 degrees, 60 degrees, and 90 degrees was 89% +/- 9%, 82% +/- 11%, and 76% +/- 8% of that at 0 degrees, respectively. Values of the 2-mm gap formation force and ultimate strength were statistically the lowest in the group with a pulling angle of 90 degrees. There was no statistically significant difference in repair strength between tendons tested at 0 degrees and those in the model without pulleys. The strength of tendon repair changed considerably according to direction of tension added to the tendons. The gap formation force and ultimate strength decreased as angles of tension increased. The results imply that a repaired tendon will be weakened as the finger is increasingly flexed. The decrease in repair strength should therefore be considered in planning a tendon suture to tolerate active finger flexion and a tendon motion protocol after primary tendon repair.

Novel chiral imidazole cyclophane receptors: synthesis and enantioselective recognition for amino acid derivatives

Novel chiral imidazole cyclophane receptors were synthesized by highly selective N-alkylation of the imadazolyl 1N-position of the bridged histidine diester 2 with the dibromide in the presence of NaH; these receptors exhibit good chiral recognition toward the enantiomers of L- and D-amino acid derivatives (up to KD/KL = 3.52, delta delta G0 = -3.11 kJ mol-1) in CHCl3 at 25.0 degrees C.

Effect of A3 pulley and adjacent sheath integrity on tendon excursion and bowstringing

The effect of the A3 pulley and adjacent sheath integrity on tendon function at the proximal interphalangeal (PIP) joint was investigated in 21 fingers in 7 fresh-frozen cadaver hands. Excursions of the flexor digitorum profundus (FDP) tendons were measured when the tendons were pulled to produce PIP joint flexion of 110 degrees from a resting position of 0 degrees. Excursions of the FDP tendons in 10 fingers were tested within the intact sheath and after incision of the A3 pulley, of the A3 pulley with its proximal sheath up to the distal border of the A2 pulley, and of the sheath between the A2 and A4 pulleys. Eleven fingers were tested after incision of the A3 pulley, of the A3 pulley and its distal sheath up to the A4 pulley, and of the sheath from the A3 to A4 pulleys. Excursions of the FDP tendons increased to 103% +/- 3% after incision of the A3 pulley, 110% +/- 4% after incision of the A3 pulley and its proximal sheath, and 107% +/- 6% after incision of the A3 pulley and its distal sheath. Excursions increased to 116% +/- 6% after incision of the sheath from the A3 to A4 pulleys and to 119% +/- 3% after incision of the sheath between the A2 and A4 pulleys. Tendon bowstringing was 0.3 mm after incision of the A3 pulley, 0.6 mm after incision of the A3 pulley with its distal sheath, 0.8 mm after incision of the pulley with its proximal sheath, 1.4 mm after incision of the sheath from the A3 to A4 pulleys, and 1.6 mm after incision of the sheath between the A2 and A4 pulleys. The results suggest that the sheath adjacent to the A3 pulley plays an important role in restraining tendon bowstringing at the PIP joint, whereas the A3 pulley alone is of little importance. This study elucidates the role of individual parts of the sheath around the PIP joint in maintaining tendon function and may guide decisions regarding the area and length of the sheath feasible for surgical release or requiring repair in the treatment of tendon lacerations.

Biomechanical evaluation of flexor tendon repair techniques

Immediate active mobilization of repaired tendons is thought to be the most effective way to restore function of injured flexor tendons. Sixty human flexor digitorum profundus tendons were used to evaluate techniques for active tendon motion. The tendons were divided equally into six groups, and each group was assigned to one of the following techniques: Kessler core suture plus running peripheral suture, Kessler plus cross-stitch suture, Kessler plus Halsted suture, Tang core suture plus running peripheral suture, Tang plus cross-stitch suture, or Tang plus Halsted suture. Immediately after tendon repair, an Instron tensile testing machine was used to measure the 2-mm gap formation force, ultimate strength, elastic modulus, and energy to failure of the tendons repaired by these techniques. Ultimate strength, elastic modulus, and energy to failure were measured in load displacement curve. Results showed that the ultimate strength of the Tang plus Halsted or cross-stitch was, respectively, 116.8 +/- 9.6 N and 94.6 +/- 7.8 N; and 2-mm gap formation force was, respectively, 86.6 +/- 4.9 N and 71.9 +/- 5.1 N. The Tang plus Halsted or cross-stitch methods had a statistically significant increase in ultimate strength and 2-mm gap formation force as compared with the Kessler core suture or Tang plus running peripheral suture method. Elastic modulus and energy to failure of the Tang plus Halsted or cross-stitch suture were statistically higher than those of other techniques. The Tang plus cross-stitch or Tang plus Halsted sutures had the highest strength among the tested methods and are appropriate techniques for tendon repair in which the goal is immediate active tendon motion.

A biomechanical study of Tang's multiple locking techniques for flexor tendon repair

This study was designed to biomechanically compare Tang's multiple looped locking techniques with various suture techniques for flexor tendon repair in the hand. Fifty flexor digitorum profondus tendons taken from pig toes were used as models; The tendons were transected in the middle part of zone 2 defined as the area beneath bifurcation of the flexor digitorum superficialis tendons, and were repaired by five different suture methods: (1) modified Kessler, (2) Tsuge's suture, (3) double Kessler, (4) modified Kessler plus Tsuge, and (5) Tang's suture. The repaired tendons were placed in an Instron tensile testing machine to determine the tensile properties of the repair. 2 mm gap formation force and ultimate tensile strength were measured during the test. Maximal work to failure were calculated according to area under the load-displacement curve of the test. 2 mm gap formation force was 21.5 N for the Kessler, 20.6 N for the Tsuge, 31.6 N for double Kessler, 30.9 N for the Kessler plus Tsuge and 41.4 N for the Tang. Ultimate tensile strength was 23.5 N for the Kessler, 22.9 N for the Tsuge, 34.5 N for the Kessler plus Tsuge and 45.6 N for the Tang. Statistically, Tang's suture had the greatest gap formation force, ultimate strength and energy for failure among the five techniques (p < 0.01 or p < 0.001). Gap formation force, ultimate strength and energy to failure for double Kessler or the Kessler plus Tsuge were significantly greater than those for the Kessler or the Tsuge (p < 0.05 or < 0.01). The tendons repaired by Tang's method tolerated a significantly higher tensile load (133 to 198% of the other techniques) than the other methods. Among the methods tested, Tang's multiple looped locking suture provides sufficient gap resistance and tensile strength that may be able to withstand early active mobilization after primary flexor tendon repair.

A new efficient synthetic method for 2- and 4-hydroxy-17 alpha-ethynylestradiol

The reaction of ethyl magnesium bromide and 17 alpha-ethynylestradiol with formaldehyde in the presence of triethyl phosphate or hexamethylphosphoramide gave the 2- and 4-formyl-17 alpha-ethynylestradiol in high yield. Treatment of the formyl derivatives with an alkaline solution of hydrogen peroxide in tetrahydrofuran afforded the corresponding catechols in almost quantitative yield. This new synthetic method was far superior to other methods, especially concerning simplicity, selectivity, and high yields.