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Delivery of recombinant adeno-associated virus vectors to rat diaphragm muscle via direct intramuscular injection.

The diaphragm is the most important inspiratory muscle in all mammals, and ventilatory insufficiency caused by diaphragm dysfunction is the leading cause of morbidity and mortality in many genetic and acquired diseases affecting skeletal muscle. Currently, pharmacological inhibitors, genetically modified animals, and invasive procedures are used to study disorders affecting the diaphragm. However, these methodologies can be problematic because of off-target drug effects and the possible nonphysiological consequences of lifelong genetic alterations. Therefore, alternative methods to study this important respiratory muscle are needed. To resolve this, we have developed a methodology to deliver recombinant adeno-associated virus (rAAV) vectors to the rat diaphragm via direct intramuscular injection. We hypothesized that by direct injection of rAAV into the muscle we can selectively target the diaphragm and establish a novel experimental method for studying signaling pathways and also provide a strategy for effectively using rAAV to protect the diaphragm against disease. This report describes the methods and evidence to support the use of rAAV as a therapeutic intervention to study rat diaphragm biology during conditions that promote diaphragm dysfunction.

Animals

Mitochondrial Lon Peptidase 1 Controls Diaphragm and Lung Development in a Context-Dependent Manner.

Congenital Diaphragmatic Hernia (CDH) is a rare neonatal disorder causing diaphragmatic defects and cardiopulmonary hypoplasia, traditionally attributed to mechanical compression from organ herniation. However, emerging evidence suggests genetic mutations may independently impair lung development, prompting debate over CDH etiology. Here, we investigated the requirement of mitochondrial function guarded by LON peptidase 1 (Lonp1), a CDH risk gene, in either diaphragm or lung development. Lonp1 loss in skeletal muscles of the diaphragm led to its thinning and membranization, recapitulating the pathology of sac-type CDH. On the other hand, lung-specific inactivation caused severe hypoplasia with defective branching morphogenesis, independent of diaphragm anomalies. Molecularly, Lonp1 disruption dysregulated key transcription factors and signaling pathways known to be critical for early lung development. Our findings here revealed that mitochondrial defects contribute to the pathogenesis of CDH in an organ and cell type specific manner, opening new avenues for drug and therapeutic development.

CDH

Adding Rib Mobilization to Diaphragm Release Techniques in Patients With Non-Specific Neck Pain: Randomized Controlled Trial.

BACKGROUND: Non-specific neck pain (NSNP) is a frequent issue that can negatively affect both mobility and function. Recently, there has been growing interest in newer therapeutic approaches, including rib mobilization and diaphragm release techniques, as potential ways to address NSNP and support better outcomes for those affected. PURPOSE: To find out the immediate effects of how (DRT) combined with (RMT) affects the level of pain and the extent to which patients' functional abilities are improved in cases of NSNP. METHODS: For this prospective RCT, 96 participants aged 20 to 45 years were randomly assigned to one of three equal groups based on their pain score (VAS). Group B engaged in (DRT) for 40 minutes, three times weekly for 8 weeks, in contrast to Group A, which got both RMT combined with DRT. Group C (active control) received advice and some exercises. Measurements were collected before and after the intervention; the primary outcomes included pain severity, evaluated using a visual analog scale (VAS); active neck range of motion (ROM), measured with a cervical range of motion (CROM) device; and neck flexion endurance. Additionally, the secondary outcome of neck-related disability was assessed using the Neck Disability Index (NDI). RESULTS: No statistically significant difference was identified among the three groups at baseline; nevertheless, a treatment effect emerged after 8 weeks (p = 0.001 and f-value = 4.15, ƞ2 = 0.306). A statistically significant time-treatment interaction was seen when comparing the pre- and post-treatment periods in groups A and B (p = 0.001, f-value = 3.16, ƞ2 = 0.251). CONCLUSION: The addition of rib mobilization to diaphragm release techniques in patients with non-specific neck pain resulted in statistically significant improvements in pain intensity, cervical flexion, right lateral rotation, left lateral rotation, right rotation, and neck flexor endurance, with moderate to large effect sizes for pain reduction and cervical motion. However, no statistically significant differences were observed between groups for cervical extension, left rotation, or the Neck Disability Index (NDI), and only a marginal clinical improvement in NDI was noted in Group A. The observed benefits in the combined intervention group may not be attributable solely to rib mobilization. The increased treatment complexity and greater therapist interaction inherent in the combined approach could also have influenced the outcomes. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT07133646.

Humans

Comparison of VCV and PCV-VG modes on diaphragmatic function in diabetic patients undergoing laparoscopic colorectal surgery: a prospective randomized controlled study.

BACKGROUND: Diabetic patients are prone to induce diaphragmatic weakness, which can lead to postoperative pulmonary complications (PPCs). The optimal mechanical ventilation mode may potentially improve postoperative diaphragmatic function. This study evaluates the effects of two ventilation modes under driving pressure-guided ventilation strategy on diaphragmatic function, as assessed by diaphragm thickening fraction (DTF) and diaphragm excursion (DE), in diabetic patients following laparoscopic colorectal surgery. METHODS: Eighty patients diagnosed with Type II diabetes scheduled for elective laparoscopic colorectal surgery, were randomly allocated to either the pressure-controlled volume-guaranteed ventilation (PCV-VG) group (Group P) or the volume-controlled ventilation (VCV) group (Group V) during surgery. The primary outcome was diaphragmatic function assessed during both tidal breathing and maximal inspiratory effort after surgery. Secondary outcomes included intraoperative mechanical power, PPCs, and other complications. RESULTS: A total of eighty patients were included in the final analysis. The averaged area under the curve (AUC) for mechanical power during ventilation was significantly lower in Group P than in Group V (p = 0.002). PCV-VG significantly improved both DE and DTF within the first two days post-surgery (AUCDEtidal: p = 0.088, AUCDTFtidal: p = 0.004, AUCDEmax: p = 0.029, AUCDTFmax: p = 0.017). Postoperative diaphragmatic weakness was less frequent in Group P than in Group V (p = 0.019). However, there was no difference in the incidence of PPCs between the two groups (p = 0.155). CONCLUSION: PCV-VG mode can reduce intraoperative mechanical power, better preserve postoperative diaphragmatic function. However, these improvements did not translate into clinical benefits, as evidenced by the lack of reduction in the incidence of PPCs.

Humans

Impact on analgesia, diaphragmatic function, and recovery between erector spinae plane block versus superior trunk block in arthroscopic shoulder surgery: a randomized controlled trial.

BACKGROUND: Effective analgesia and preservation of diaphragmatic function are key considerations in analgesia for shoulder surgery. The superior trunk block provides analgesia with reduced phrenic nerve involvement, while the erector spinae plane block offers minimal impact on diaphragm motion. This randomized controlled trial compared the analgesic efficacy, impact on diaphragmatic motion, and postoperative recovery between the two blocks. METHODS: Sixty patients undergoing arthroscopic shoulder surgery were randomized to receive either erector spinae plane block or superior trunk block. Primary outcomes were postoperative VAS and changes in diaphragmatic excursion. Secondary outcomes included Quality of Recovery-15 (QoR-15) scores, morphine-equivalent consumption, and the handgrip strength motor blockade. RESULTS: The superior trunk block resulted in significantly lower dynamic VAS at 1-h postoperatively (0.1 [0.0, 0.2] vs. 5.7 [4.0, 7.6]; p&#x2009;<&#x2009;0.001) and reduced 24-h morphine consumption (7.8 [2.5, 15.0] mg vs. 12.7 [7.5, 17.3] mg; p&#x2009;=&#x2009;0.038) compared to the erector spinae plane block. However, diaphragmatic excursion was better preserved in the erector spinae plane block group (8.37% &#xb1; 20.7% vs. -20.09% &#xb1; 22.2%; p&#x2009;<&#x2009;0.001), with a lower incidence of partial hemidiaphragm paresis (3.3% vs. 46.7%; p&#x2009;<&#x2009;0.001). At 24&#x2009;h postoperatively, QoR-15 scores were higher in the superior trunk block group (p&#x2009;=&#x2009;0.047), and no patient in either group developed handgrip motor blockade. CONCLUSIONS: Superior trunk block offers superior early postoperative analgesia and better overall recovery, while erector spinae plane block minimizes diaphragmatic impairment. However, the erector spinae plane block may represent an option only in carefully selected patients at high respiratory risk, acknowledging its significantly poorer early analgesic profile.

Humans

Disease-driven post-transcriptional alterations and alternative splicing in podocytes in focal segmental glomerulosclerosis.

Focal segmental glomerulosclerosis (FSGS) is a major cause of nephrotic syndrome and progression to end-stage renal disease, yet its molecular pathogenesis remains still incompletely defined. While transcriptional alterations in podocytes have been extensively characterized, the contribution of post-transcriptional regulatory mechanisms is poorly understood. Here, we combined a zebrafish podocyte-specific injury model with glomerulus-resolved transcriptomic profiling to dissect RNA regulatory alterations during FSGS progression. Integrated analyses of bulk RNA sequencing, small RNA profiling, and alternative splicing revealed pronounced, time-dependent remodeling of the glomerular transcriptome. We demonstrate that podocyte injury is associated with loss of key podocyte-specific proteins, activation of inflammatory pathways, remodeling of the extracellular matrix, and altered microRNA expression, such as miR-21 and miR-193. Moreover, we found that alternative splicing influences key podocyte gene expression, affecting genes critical for slit diaphragm integrity, actin cytoskeleton organization, and glomerular basement membrane stability. Isoform analyses identified FSGS-associated isoform switches in SRSF3 and EPB41L5. Importantly, these changes were also evident in glomeruli from FSGS patients, demonstrating that the zebrafish model recapitulates key molecular features of human disease and highlighting alternative splicing as a central regulatory mechanism in FSGS.

Animals

Assessment of systemic AAV-microdystrophin gene therapy in the GRMD model of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disease caused by the absence of dystrophin, a membrane-stabilizing protein encoded by the DMD gene. Although mouse models of DMD provide insight into the potential of a corrective therapy, data from genetically homologous large animals, such as the dystrophin-deficient golden retriever muscular dystrophy (GRMD) model, may more readily translate to humans. To evaluate the clinical translatability of an adeno-associated virus serotype 9 vector (AAV9)-microdystrophin (&#x3bc;Dys5) construct, we performed a blinded, placebo-controlled study in which 12 GRMD dogs were divided among four dose groups [control, 1 &#xd7; 1013 vector genomes per kilogram (vg/kg), 1 &#xd7; 1014 vg/kg, and 2 &#xd7; 1014 vg/kg; n = 3 each], treated intravenously at 3 months of age with a canine codon-optimized microdystrophin construct, rAAV9-CK8e-c-&#x3bc;Dys5, and followed for 90 days after dosing. All dogs received prednisone (1 milligram/kilogram) for a total of 5 weeks from day -7 through day 28. We observed dose-dependent increases in tissue vector genome copy numbers; &#x3bc;Dys5 protein in multiple appendicular muscles, the diaphragm, and heart; limb and respiratory muscle functional improvement; and reduction of histopathologic lesions. As expected, given that a truncated dystrophin protein was generated, phenotypic test results and histopathologic lesions did not fully normalize. All administrations were well tolerated, and adverse events were not seen. These data suggest that systemically administered AAV-microdystrophin may be dosed safely and could provide therapeutic benefit for patients with DMD.

Animals

Acetazolamide to prevent ventilatory drive withdrawal in REM sleep apnoea: a randomised controlled trial.

BACKGROUND: Obstructive sleep apnoea (OSA) pathogenesis during rapid-eye movement (REM) sleep has been linked to dips in ventilatory drive and downstream genioglossus hypotonia. The carbonic anhydrase inhibitor acetazolamide is known to increase ventilatory drive and improve OSA severity. Therefore, we tested the effect of acetazolamide on REM-predominant OSA severity (apnoea hypopnoea index (AHI) and hypoxic burden, co-primary outcomes) and underlying physiological mechanisms (ventilatory drive, ventilation and pharyngeal muscle activity). METHODS: 11 participants with REM-predominant OSA per baseline polysomnography (REM AHI/non-REM AHI&#x2265;2) were allocated to receiving acetazolamide 500&#x2009;mg for three nights (first night at half dose) or placebo according to a randomised, crossover, double-blind design. Detailed physiological polysomnography with recording of diaphragm and genioglossus electromyography was conducted after each intervention, with a 1-week washout in between. RESULTS: As hypothesised, acetazolamide reduced AHI by 35.5% (95% CI 23.1% to 46.3%) and hypoxic burden by 35.9% (95% CI 21.1% to 48.4%) vs placebo (p<0.001), meeting the primary endpoint. Mechanistic analysis in REM revealed that, unexpectedly, acetazolamide did not mitigate dips in ventilatory drive versus placebo (first decile (+0.1 (-1.0 to 1.3) L/min, p=0.8). Rather, acetazolamide reduced collapsibility (increased ventilation at eupneic drive: +1.4 (1.2 to 1.8) L/min) and raised muscle responsiveness (ventilation vs drive slope: +32 (25 to 41) %ventilation/drive, p<0.001; genioglossus versus drive slope: +0.33 (0.13 to 0.54) %max/(L/min), p=0.001). CONCLUSIONS: Acetazolamide modestly improved REM OSA, with meaningful improvements in upper airway physiology, but failed to mitigate the dips in ventilatory drive responsible for REM OSA. TRIAL REGISTRATION NUMBER: NCT05589792.

Humans

Partially countering the physiological effects of fentanyl with naloxone or d-cysteine ethyl ester in adult goats.

Fentanyl is the leading contributor to opioid-involved overdose (OD) mortality in the United States. Despite the demonstrated efficacy, safety, and wide availability of naloxone (NAL), opioid-involved OD fatalities remain high. This suggests our understanding of the negative integrated physiological effects of fentanyl remains incomplete, and highlights the need to develop additional novel countermeasures. Here we tested whether the physiological and behavioral effects of intravenous fentanyl in adult female goats (n = 12) could be mitigated with NAL or the potential countermeasure d-cysteine ethyl ester (d-CYSee). As hypothesized, intravenous injections of high doses (HD) fentanyl caused immediate ventilatory suppression via reduced breathing frequency leading to hypoventilation and hypoxemia (&#x2265;10 min). HD fentanyl elicited immediate and sustained (&#x2265;90 min) increases in diaphragm, intercostal, abdominal, and laryngeal constrictor muscle activity along with an increased alveolar to arterial oxygen (A-a O2) gradient and hypertension. Intravenous NAL administered immediately following HD fentanyl mitigated most of these effects except the increased activation of respiratory pump and airway muscles. In contrast, d-CYSee administration immediately following HD fentanyl countered the initial hypoventilation but did not mitigate the increases in muscle activation and persistent hypoxemia. Neither treatment prevented acute withdrawal-like behaviors emerging >90 min after fentanyl administration. The data suggest that there are physiological effects of HD fentanyl that are NAL-insensitive, and d-CYSee can transiently normalize blood gases and counter opioid-induced respiratory depression (OIRD) in adult goats.NEW & NOTEWORTHY Here we determined whether any of the deleterious physiological effects of high-dose fentanyl could be countered by naloxone and/or d-cysteine ethyl ester (d-CYSee) in adult goats. Fentanyl induced hypoventilation and sustained increases in respiratory and airway muscle activity and hypoxemia. Naloxone reversed all fentanyl effects except tonic muscle activation, and d-CYSee reversed fentanyl-induced hypoventilation. These data suggest some effects of fentanyl are naloxone-insensitive and that d-CYSee may be a valuable countermeasure for OIRD.

Animals