1
|
Kim T, van Bakel PAJ, Nama N, Burris N, Patel HJ, Williams DM, Figueroa CA. A Computational Study of Dynamic Obstruction in Type B Aortic Dissection. J Biomech Eng 2023; 145:031008. [PMID: 36459144 PMCID: PMC10854260 DOI: 10.1115/1.4056355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 12/05/2022]
Abstract
A serious complication in aortic dissection is dynamic obstruction of the true lumen (TL). Dynamic obstruction results in malperfusion, a blockage of blood flow to a vital organ. Clinical data reveal that increases in central blood pressure promote dynamic obstruction. However, the mechanisms by which high pressures result in TL collapse are underexplored and poorly understood. Here, we developed a computational model to investigate biomechanical and hemodynamical factors involved in Dynamic obstruction. We hypothesize that relatively small pressure gradient between TL and false lumen (FL) are sufficient to displace the flap and induce obstruction. An idealized fluid-structure interaction model of type B aortic dissection was created. Simulations were performed under mean cardiac output while inducing dynamic changes in blood pressure by altering FL outflow resistance. As FL resistance increased, central aortic pressure increased from 95.7 to 115.3 mmHg. Concurrent with blood pressure increase, flap motion was observed, resulting in TL collapse, consistent with clinical findings. The maximum pressure gradient between TL and FL over the course of the dynamic obstruction was 4.5 mmHg, consistent with our hypothesis. Furthermore, the final stage of dynamic obstruction was very sudden in nature, occurring over a short time (<1 s) in our simulation, consistent with the clinical understanding of this dramatic event. Simulations also revealed sudden drops in flow and pressure in the TL in response to the flap motion, consistent with first stages of malperfusion. To our knowledge, this study represents the first computational analysis of potential mechanisms driving dynamic obstruction in aortic dissection.
Collapse
Affiliation(s)
- T Kim
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48105
| | - P A J van Bakel
- Department of Cardiac Surgery, University of Michigan, Ann Arbor, MI 48105
| | - N Nama
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588
| | - N Burris
- Department of Radiology, University of Michigan, Ann Arbor, MI 48105
| | - H J Patel
- Department of Cardiac Surgery, University of Michigan, Ann Arbor, MI 48105
| | - D M Williams
- Department of Radiology, University of Michigan, Ann Arbor, MI 48105
| | - C A Figueroa
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48105; Department of Surgery, University of Michigan, Ann Arbor, MI 48105
| |
Collapse
|
2
|
Ballotta AB, Kandil H, Montgomery DG, Ranucci M, Trimarchi S, Myrmel T, Bavaria JE, Sundt TM, Bossone E, Suzuki T, Ota T, Nienaber CA, Isselbacher EM, Eagle KA, Patel HJ. P5608Acute respiratory failure after type A aortic dissection repair: data from the International Registry of Aortic Dissection (IRAD). Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz746.0552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Acute Respiratory Failure (ARF) has been noted in up to 20% of patients undergoing cardiac surgery and is associated with increased mortality. Cardiopulmonary bypass (CPB) is often followed by pulmonary dysfunction, although literature on the subject in the setting of Type A acute aortic dissection (TAAAD) is limited.
Methods
This study identified the incidence of ARF after TAAAD, associated risk factors, and the impact of ARF on early and late outcomes. All data have been derived from the International Registry of Acute Aortic Dissection (IRAD).
Results
Postoperative ARF (defined as ventilator support for ≥3 days, tracheostomy, and/or pneumonia) occurred in 434 (24.6%) of 1764 surgically managed TAAAD patients (mean age 60.1±14.2 years) from November 2001 until November 2017. Peripheral vessel procedures (6.4% v 2.8%, p=0.002), cerebral perfusion (89.2% v 82.3%, p<0.001), use of hypothermic circulatory arrest (93% v 87.7%), longer arrest time (median 39 (Q1-Q3 27–128 minutes) v 31 (Q1-Q3 22.0–52.9 minutes)), and lower extremity ischemia (18.8% v 6.7%, p<0.001) were more common in ARF patients.
On multivariable logistic regression analysis, age ≥70 years (OR 1.019, 95% CI 1.005–1.034, p=0.008), current smoking (OR 1.744, 95% CI 1.184–2.570, p=0.005), peripheral vessel procedures (OR 2.457, 95% CI 1.132–5.334, p=0.023), presenting hypotension/shock (OR 2.036, 95% CI 1.336–3.102, p=0.001), lower extremity ischemia at surgery (OR 2.77, 95% CI 1.574–4.875, p<0.001), concomitant coronary artery bypass graft (CABG) (OR 2.982, 95% CI 1.597–5.568, p=0.001), pre-operative acute renal failure (OR 2.532, 95% CI 1.350–4.749, p=0.004), and prolonged circulatory arrest time in minutes (OR 1.005, 95% CI 1.003–1.007, p<0.001) were independently associated with ARF development. Patients with aortic valve replacement (AVR) were less likely to develop ARF (OR 0.497, 95% CI 0.308–0.802, p=0.004).
Post-operative complications were more common in ARF patients. In-hospital mortality was higher in the ARF cohort (16.4% v 4.7%, p<0.001). Multivariable logistic regression identified ARF (OR 2.686, 95% CI 1.647–4.381, p<0.001) as well as pre-operative hypotension (OR 1.89, 95% CI 1.130–3.159, p=0.015), lower extremity ischemia (OR 2.77, 95% CI 1.545–4.998, p=0.001), pre-operative myocardial infarction (OR 3.141, 95% CI 1.058–9.33, p=0.039), and CABG (OR 1.988, 95% CI 1.011–3.909, p-value 0.047) as independent predictors of death.
Conclusions
Post-operative ARF is common after TAAAD repair; in-hospital complications and death are higher in this cohort.
Acknowledgement/Funding
W.L. Gore & Associates, Inc.; Medtronic; Varbedian Aortic Fund; Hewlett Foundation; Mardigian Foundation; UM Faculty Group Practice; Ann & Bob Aikens
Collapse
Affiliation(s)
- A B Ballotta
- IRCCS, Policlinico San Donato, Thoracic Aortic Research Center, San Donato Milanese, Italy
| | - H Kandil
- IRCCS, Policlinico San Donato, Thoracic Aortic Research Center, San Donato Milanese, Italy
| | - D G Montgomery
- University of Michigan, Ann Arbor, United States of America
| | - M Ranucci
- IRCCS, Policlinico San Donato, Thoracic Aortic Research Center, San Donato Milanese, Italy
| | - S Trimarchi
- IRCCS Fondazione Ca Granda Ospedale Maggiore Policlinico, Department of Scienze Biomediche per la Salute, Milan, Italy
| | - T Myrmel
- Tromso University Hospital, Department of Thoracic and Cardiovascular Surgery, Tromso, Norway
| | - J E Bavaria
- University of Pennsylvania, Division of Cardiothoracic Surgery, Philadelphia, United States of America
| | - T M Sundt
- Massachusetts General Hospital, Thoracic Aortic Center, Boston, United States of America
| | - E Bossone
- University of Salerno, Salerno, Italy
| | - T Suzuki
- University of Leicester, Leicester, United Kingdom
| | - T Ota
- University of Chicago Medicine, Center for Aortic Diseases, Chicago, United States of America
| | | | - E M Isselbacher
- Massachusetts General Hospital, Thoracic Aortic Center, Boston, United States of America
| | - K A Eagle
- University of Michigan, Ann Arbor, United States of America
| | - H J Patel
- University of Michigan, Ann Arbor, United States of America
| |
Collapse
|
3
|
Patel K, Patel HJ, Christian J, Hingorani L, Gandhi T. Analytical QbD: Designing Space for HPLC Method Operable Region for Estimation of Preservatives in Herbal Formulation. CURR PHARM ANAL 2019. [DOI: 10.2174/1573412914666171218151224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
Quantification of preservatives in herbal formulation, simultaneously by high
performance liquid chromatography analysis is very complex and involves series of steps including
sample preparation, selection of suitable mobile phase and its validation for routine applications.
</P><P>
Introduction: Application of Quality by Design (QbD) in the development of novel, simple, accurate
and precise RP-HPLC method for concurrent quantification of quaternary preservatives in herbal formulation,
focusses on development of robust method.
Methods:
Isocratic analysis was carried out using C18 column at 231 nm. Risk assessment studies were
executed to determine the critical method parameters which were defined as acetonitrile volume in the
mobile phase, volume of injection and orthophosphoric acid concentration in the mobile phase. The
effect of the critical method parameters on critical method attributes, i.e. retention time, resolution and
chromatographic optimization function was further evaluated by means of central composite design and
the optimal conditions were determined through derringer’s desirability approach of multi-criteria decision
making technique.
Results:
The method was statistically validated according to ICH guidelines having good resolution
using optimized mobile phase, acetonitrile: 0.11% orthophosphoric acid in water (12.30: 87.70 % v/v)
giving acceptable retention time i.e. 3.7128 ± 0.0138 of bronopol, 4.5106 ± 0.00542 of sodium propyl
paraben, 10.7228 ± 0.029 of sodium benzoate and 12.252 ± 0.027 of sodium methyl paraben.
Conclusion:
Hence, the QbD based method development assisted in generating a design space with
knowledge of all method performance characteristics leading to a better understanding of the method,
and achieving desirable method quality.
Collapse
Affiliation(s)
- Kalpana Patel
- Anand Pharmacy College, Anand, Opp. Town Hall, SRKSM Campus, Anand - 388001, Gujarat, India
| | | | - Jenee Christian
- Anand Pharmacy College, Anand, Opp. Town Hall, SRKSM Campus, Anand - 388001, Gujarat, India
| | | | - Tejal Gandhi
- Anand Pharmacy College, Anand, Opp. Town Hall, SRKSM Campus, Anand - 388001, Gujarat, India
| |
Collapse
|
4
|
Patel HJ, Li J, Gonzalez-Angulo AM, Strom E, Perkins GH, Tereffe W, Yu TK, Hoffman K, Smith BD, Lucci A, Valero V, Buchholz TA, Woodward W. Abstract P1-17-02: Outcome after Locoregional Recurrence in Patients with Inflammatory Breast Cancer. Cancer Res 2010. [DOI: 10.1158/0008-5472.sabcs10-p1-17-02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Purpose: High rates of locoregional recurrence (LRR) have been reported in spite of comprehensive tri-modality therapy for patients with inflammatory breast cancer (IBC). The aim of this study was to examine the prognosis of patients who have experienced LRR after treated primary IBC. Methods:
We retrospectively reviewed information for 124 IBC patients who experienced a LRR seen in our institution from 1990-2008. 63 patients had simultaneous distant disease (DM) +/−3 months of LRR (simLRR),
5 patients had LRR > 3 months subsequent to DM, while 56 patients had isolated LRR >3 months prior to DM (isLRR). Overall survival (OS) was calculated from date of recurrence using the Kaplan-Meier method. Results:
Median time to LRR from diagnosis was 13 months (interquartile range 8-21 months). Median survival after LRR was 15 months. 2-yr OS was 46%. Regarding the primary tumors, 23% were estrogen receptor positive (ER+), 33% were HER2-neu positive (H2N+), 81% had lymph vascular space invasion (LVSI), and 83% were grade 3. Comparing isLRR and simLRR cohorts, median survival was 18 months vs. 10 months and 2 yr-OS was 66% vs. 28%, respectively. ER+ and H2N+ primary status predicted for longer 2 yr OS among patients with simLRR but not among isLRR patients. (simLRR, ER+ 57% vs. ER-19% p = 0.02, H2N+ 45% vs. H2N-17% p = 0.01; IsLRR ER+ vs. ER-92% vs. 55% p = 0.15, H2N+ 86% vs. H2N-57% p = 0.11). LVSI was not prognostic in either group and Grade 3 primary trended towards worse outcome among isLRR cohort only, Grade 2 83% vs. Grade 3 64% P = 0.08. Molecular subtyping using ER and H2N status to group tumors demonstrates basal subtype in the primary tumor compared to H2N, luminal B and luminal A is associated with significantly worse 2 yr OS after isLRR (43% vs. 88%, 82%, and 83%, P = 0.04) and simLRR (13% vs. 34%, 80%, 32% P = 0.005) respectively. Conclusions:
Forty-five% of LRR occurred as isolated first events. LRRs generally occur within 2 years after primary IBC treatment and are associated with poor outcomes even as first events. Basal subtype predicts for worse overall survival regardless of distant disease.
Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-17-02.
Collapse
Affiliation(s)
- HJ Patel
- The University of Texas M. D. Anderson Cancer Center, Houston
| | - J Li
- The University of Texas M. D. Anderson Cancer Center, Houston
| | | | - E Strom
- The University of Texas M. D. Anderson Cancer Center, Houston
| | - GH Perkins
- The University of Texas M. D. Anderson Cancer Center, Houston
| | - W Tereffe
- The University of Texas M. D. Anderson Cancer Center, Houston
| | - T-K Yu
- The University of Texas M. D. Anderson Cancer Center, Houston
| | - K Hoffman
- The University of Texas M. D. Anderson Cancer Center, Houston
| | - BD Smith
- The University of Texas M. D. Anderson Cancer Center, Houston
| | - A Lucci
- The University of Texas M. D. Anderson Cancer Center, Houston
| | - V Valero
- The University of Texas M. D. Anderson Cancer Center, Houston
| | - TA Buchholz
- The University of Texas M. D. Anderson Cancer Center, Houston
| | - W. Woodward
- The University of Texas M. D. Anderson Cancer Center, Houston
| |
Collapse
|
5
|
Yewlett A, Oakley J, Makwana N, Patel HJ. Retained blackthorn causing peroneal tendonitis: a case report. Foot Ankle Surg 2010; 15:205-6. [PMID: 19840753 DOI: 10.1016/j.fas.2008.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 11/15/2008] [Accepted: 11/24/2008] [Indexed: 02/04/2023]
Abstract
We present the first reported case of peroneal tenosynovitis secondary to a retained blackthorn in a patient with a 4 months history of persistent pain and swelling around her lateral malleolus following a penetrating injury. Ultrasonography reported considerable subcutaneous fluid but no identifiable foreign body. Magnetic resonance imaging confirmed peroneal sheath synovitis with a possible retained foreign body posteriorly. Surgical exploration revealed marked synovitis and chronic inflammation of the peroneal sheath with the tip of a blackthorn deep to peroneus longus. This case illustrates the many ways in which penetrating blackthorn injuries may present. In particular it highlights the need for a high index of suspicion for retained foreign material and the need for further imaging and surgical exploration when symptoms do not resolve.
Collapse
Affiliation(s)
- Alun Yewlett
- Wrexham Maelor Hospital, Orthopaedics, 141 Heol Isaf, Cardiff, United Kingdom.
| | | | | | | |
Collapse
|
6
|
Freund-Michel VC, Birrell MA, Patel HJ, Murray-Lyon IM, Belvisi MG. Modulation of cholinergic contractions of airway smooth muscle by cathinone: potential beneficial effects in airway diseases. Eur Respir J 2009; 32:579-84. [PMID: 18757696 DOI: 10.1183/09031936.00162707] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Infusion of khat leaves is an African traditional remedy used to treat airway diseases. The beneficial effects of khat are thought to be due to the activity of its main active component, cathinone. Cathinone inhibited electric field stimulation-induced acetylcholine release and the contractions of smooth muscle, which could be responsible for the beneficial effects seen in airway disease. The mechanism of action of this natural product appears to be via the activation of both pre-junctional alpha(2) adrenergic and 5-hydroxytryptamine 7 receptors. The present novel study describes how cathinone modulates airway tone, and may go some way to explaining the traditional use of khat as a remedy for the alleviation of respiratory disease symptoms. In conclusion, cathinone may have beneficial effects in airway diseases with heightened cholinergic tone. There is some rationale for follow-up of these observations, given previous experience of other traditional remedies being developed for therapeutic use.
Collapse
Affiliation(s)
- V C Freund-Michel
- Respiratory Pharmacology, Airway Disease Section, National Heart and Lung Institute, Imperial College School of Medicine, Guy Scadding Building, Dovehouse Street, London SW3 6LY, UK
| | | | | | | | | |
Collapse
|
7
|
Belvisi MG, Patel HJ, Freund-Michel V, Hele DJ, Crispino N, Birrell MA. Inhibitory activity of the novel CB2 receptor agonist, GW833972A, on guinea-pig and human sensory nerve function in the airways. Br J Pharmacol 2008; 155:547-57. [PMID: 18695648 DOI: 10.1038/bjp.2008.298] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Sensory nerves regulate central and local reflexes such as airway plasma protein leakage, bronchoconstriction and cough. Sensory nerve activity may be enhanced during inflammation such that these protective effects become exacerbated and deleterious. Cannabinoids are known to inhibit airway sensory nerve function. However, there is still controversy surrounding which receptor is involved in eliciting these effects. EXPERIMENTAL APPROACH We have adopted a pharmacological approach, including using a novel, more selective CB(2) receptor agonist, GW 833972A (1000-fold selective CB(2)/CB(1)), and receptor selective antagonists to investigate the inhibitory activity of cannabinoids on sensory nerve activity in vitro and in vivo in guinea-pig models of cough and plasma extravasation. KEY RESULTS GW 833972A inhibited capsaicin-induced depolarization of the human and guinea-pig and prostaglandin E(2) (PGE(2)) and hypertonic saline-induced depolarization of the guinea-pig isolated vagus nerve in vitro. GW 833972A also inhibited citric acid-induced cough but not plasma extravasation in the guinea-pig and this effect was blocked by a CB(2) receptor antagonist. CONCLUSIONS AND IMPLICATIONS This confirms and extends previous studies highlighting the role of CB(2) receptors in the modulation of sensory nerve activity elicited both by the exogenous ligands capsaicin and hypertonic saline but also by endogenous modulators such as PGE(2) and low pH stimuli. These data establish the CB(2) receptor as an interesting target for the treatment of chronic cough.
Collapse
Affiliation(s)
- M G Belvisi
- Respiratory Pharmacology Group, Airway Disease Section, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK.
| | | | | | | | | | | |
Collapse
|
8
|
Abstract
Peroxisome proliferator-activated receptors (PPARs) are a family of ligand-activated nuclear hormone receptors belonging to the steroid receptor super-family. Previously, the present authors have shown that PPAR-gamma agonists inhibit the release of inflammatory cell survival factors and induce apoptosis in vitro. The aim of this study was to determine the effect of two structurally different PPAR agonists in an in vivo model of lipopolysaccharide (LPS)-induced airway inflammation. Mice were treated with PPAR agonists, rosiglitazone or SB 219994, prior to exposure to aerosolised LPS, and the extent of airway inflammation was assessed 3 h later. In these experiments, the PPAR ligands inhibited LPS-induced airway neutrophilia and associated chemoattractants/survival factors (keratinocyte-derived chemokine and granulocyte-colony stimulating factor) in the mouse lung. The present authors postulate that if a peroxisome proliferator-activated receptor agonist has the same effect in man, and neutrophils are important in the progression of respiratory diseases, such as chronic obstructive pulmonary disease, then this class of compounds could be a potential therapy. Furthermore, several peroxisome proliferator-activated receptor-gamma agonists have been shown to be clinically effective for the treatment of type II diabetes, suggesting that any benefit of peroxisome proliferator-activated receptor-gamma ligands in the progression of respiratory diseases, which may involve airway neutrophilia, could be explored relatively quickly.
Collapse
Affiliation(s)
- M A Birrell
- Respiratory Pharmacology Group, Cardiothoracic Surgery, The National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK
| | | | | | | | | | | | | |
Collapse
|
9
|
Lazzeri N, Belvisi MG, Patel HJ, Chung KF, Yacoub MH, Mitchell JA. RANTES release by human airway smooth muscle: effects of prostaglandin E(2) and fenoterol. Eur J Pharmacol 2001; 433:231-5. [PMID: 11755157 DOI: 10.1016/s0014-2999(01)01520-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In human airway smooth muscle cells, the levels of RANTES were increased upon stimulation with interleukin-1beta together with tumour necrosis factor-alpha (TNF-alpha) (10 ng ml(-1) for each). In this study, we have assessed the effects of prostaglandin E(2) and the beta(2)-adrenoceptor agonist, fenoterol on RANTES (regulated upon activation, normal T cell expressed and secreted) release by these cells. The levels of RANTES released by human airway smooth muscle cells were measured after 24 h of treatment. Prostaglandin E(2) and fenoterol, only in presence of a cyclo-oxygenase inhibitor indomethacin (10(-6) M), provoked a concentration-dependent reduction in RANTES release. These data suggest that, in settings where cyclo-oxygenase activity is low, both drugs may relieve the symptoms of airway diseases by reducing RANTES production.
Collapse
Affiliation(s)
- N Lazzeri
- Thoracic Medicine, National Heart and Lung Institute, Dovehouse Street, London SW3 6LY, UK
| | | | | | | | | | | |
Collapse
|
10
|
Abstract
Elevated levels of nerve growth factor (NGF) have been detected in the bronchoalveolar lavage fluid of patients with asthma. However, the source of this enhanced mediator production is not known. Here, we investigate the production of NGF from a human airway epithelial cell line (A549). Under basal conditions, A549 cells generated NGF in a time-dependent fashion. However, basal release was significantly augmented in a concentration-dependent manner in cells treated with interleukin-1beta (IL-1beta) or tumour necrosis factor-alpha (TNF-alpha) and inhibited by dexamethasone. These data suggest that NGF released from structural cells may be an important target for the anti-inflammatory effects of steroids in asthma therapy.
Collapse
Affiliation(s)
- A J Fox
- Novartis Institute for Medical Sciences, 5 Gower Place, WC1E 6BN, London, UK
| | | | | | | |
Collapse
|
11
|
Abstract
BACKGROUND Thymectomy has become recognized as an integral element in the care of the patient with myasthenia gravis. Although the number of elderly patients with myasthenia is substantial, little data exist demonstrating the efficacy and morbidity of thymectomy in this population. STUDY DESIGN We retrospectively analyzed 126 cervicomediastinal thymectomies performed at a single university hospital from 1980 to 1998. Patients 55 years or older were compared with those less than 55. Efficacy was measured by determining the change in Osserman score, the rate of remission during followup, and the reduction in medication requirements after thymectomy. RESULTS Older patients (n = 28) had similar Osserman scores (p = 0.8) and similar rates of complete and partial remission as the younger group (n = 98) at a mean +/- SEM followup of 58 +/- 5 months. The two groups did not differ in the number (p = 0.4) and doses of medications used to control myasthenic symptoms after operation. Older age was associated with an increased length of hospitalization (13.8 +/- 3.2 days versus 9.7 +/- 0.6 days, p = 0.05) and a higher incidence of reintubation, and longer ventilatory support (2.6 +/- 1.3 days versus 0.1 +/- 0.1 days, p = 0.001). CONCLUSIONS Increased age does not alter the outcomes of thymectomy for myasthenia gravis. Older patients can expect to have similar responses and require a similar number of postoperative medications as younger patients, but with a higher short-term morbidity.
Collapse
Affiliation(s)
- P L Abt
- Department of Surgery, The University of Rochester School of Medicine and Dentistry, NY, USA
| | | | | | | |
Collapse
|
12
|
Lazzeri N, Belvisi MG, Patel HJ, Yacoub MH, Chung KF, Mitchell JA. Effects of prostaglandin E2 and cAMP elevating drugs on GM-CSF release by cultured human airway smooth muscle cells. Relevance to asthma therapy. Am J Respir Cell Mol Biol 2001; 24:44-48. [PMID: 11152649 DOI: 10.1165/ajrcmb.24.1.4027] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Human airway smooth muscle (HASM) cells release granulocyte macrophage-colony stimulating factor (GM-CSF) and express cyclooxygenase (COX)-2 (resulting in the release of prostaglandin [PG] E2) after stimulation with cytokines. Because COX-2 activity can regulate a number of inflammatory processes, we have assessed its effects, as well as those of agents that modulate cyclic adenosine monophosphate (cAMP), on GM-CSF release by HASM cells. Cells stimulated with a combination of proinflammatory cytokines (interleukin-1beta and tumor necrosis factor-alpha each at 10 ng/ml) for 24 h released significant amounts of PGE2 (measured by radioimmunoassay) and GM-CSF (measured by enzyme-linked immunosorbent assay). Indomethacin and other COX-1/COX-2 inhibitors caused concentration-dependent inhibitions of PGE2 concomitantly with increases in GM-CSF formation. Addition of exogenous PGE2 or the beta2-agonist fenoterol, which increase cAMP, to cytokine-treated HASM cells had no effect on GM-CSF release unless COX activity was first blocked with indomethacin. The type 4 phosphodiesterase inhibitors rolipram and SB 207499 both caused concentration-dependent reductions in GM-CSF production. Thus, when HASM cells are activated with cytokines they release PGE2, which acts as a "braking mechanism" to limit the coproduction of GM-CSF. Moreover, agents that elevate cAMP also reduce GM-CSF formation by these cells.
Collapse
Affiliation(s)
- N Lazzeri
- Thoracic Medicine and Cardiothoracic Surgery, National Heart and Lung Institute, London; Pharmacology Department, Dagenham Research Centre, Dagenham, Essex; and Unit of Critical Care Medicine, Royal Brompton Hospital, IC School of Medicine, London, UK
| | | | | | | | | | | |
Collapse
|
13
|
Pusca SV, Pilla JJ, Blom AS, Patel HJ, Yuan Q, Ferrari VA, Prood C, Axel L, Acker MA. Assessment of synchronized direct mechanical ventricular actuation in a canine model of left ventricular dysfunction. ASAIO J 2000; 46:756-60. [PMID: 11110276 DOI: 10.1097/00002480-200011000-00019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Direct mechanical ventricular actuation (DMVA) is an experimental procedure that provides biventricular cardiac assistance by intracorporeal pneumatic compression of the heart. The advantages this technique has over other assist devices are biventricular assistance, no direct blood contact, pulsatile blood flow, and rapid, less complicated application. Prior studies of nonsynchronized DMVA support have demonstrated that a subject can be maintained for up to 7 days. The purpose of this study was to determine the acute hemodynamic effects of cardiac synchronized, partial DMVA support in a canine model (RVP) of left ventricular (LV) dysfunction. The study consisted of rapidly pacing seven dogs for 4 weeks to create LV dysfunction. At the conclusion of the pacing period, the DMVA device was positioned around the heart by means of a median sternotomy. The animals were then imaged in a 1.5 T whole body high speed clinical MR system, with simultaneous LV pressure recording. Left ventricular pressure-volume (PV) loops of the nonassisted and DMVA assisted heart were generated and demonstrated that DMVA assist shifted the loops leftward. In addition, assist significantly improved pressure dependent LV systolic parameters (left ventricular peak pressure and dp/dt max, p < 0.05), with no diastolic impairment. This study demonstrates that DMVA can provide synchronized partial assist, resulting in a decrease in the workload of the native heart, thus having a potential application for heart failure patients.
Collapse
Affiliation(s)
- S V Pusca
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Blom AS, Pilla JJ, Pusca SV, Patel HJ, Dougherty L, Yuan Q, Ferrari VA, Axel L, Acker MA. Dynamic cardiomyoplasty decreases myocardial workload as assessed by tissue tagged MRI. ASAIO J 2000; 46:556-62. [PMID: 11016506 DOI: 10.1097/00002480-200009000-00009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The effects of dynamic cardiomyoplasty (CMP) on global and regional left ventricular (LV) function in end-stage heart failure still remain unclear. MRI with tissue-tagging is a novel tool for studying intramyocardial motion and mechanics. To date, no studies have attempted to use MRI to simultaneously study global and regional cardiac function in a model of CMP. In this study, we used MRI with tissue-tagging and a custom designed MR compatible muscle stimulating/pressure monitoring system to assess long axis regional strain and displacement variations, as well as changes in global LV function in a model of dynamic cardiomyoplasty. Three dogs underwent rapid ventricular pacing (RVP; 215 BPM) for 10 weeks; after 4 weeks of RVP, a left posterior CMP was performed. After 1 year of dynamic muscle stimulation, the dogs were imaged in a 1.5 T clinical MR scanner. Unstimulated and muscle stimulated tagged long axis images were acquired. Quantitative 2-D regional image analysis was performed by dividing the hearts into three regions: apical, septal, and lateral. Maximum and minimum principal strains (lambda, and lambda2) and displacement (D) were determined and pooled for each region. MR LV pressure-volume (PV) loops were also generated. Muscle stimulation produced a leftward shift of the PV loops in two of the three dogs, and an increase in the peak LV pressure, while stroke volume remained unchanged. With stimulation, lambda1 decreased significantly (p<0.05) in the lateral region, whereas lambda2 increased significantly (p<0.05) in both the lateral and apical regions, indicating a decrease in strain resulting from stimulation. D only increased significantly (p<0.05) in the apical region. The decrease in strain between unassisted and assisted states indicates the heart is performing less work, while maintaining stroke volume and increasing peak LV pressure. These findings demonstrate that the muscle wrap functions as an active assist, decreasing the workload of the heart, while preserving total pump performance.
Collapse
Affiliation(s)
- A S Blom
- Department of Radiology, University of Pennsylvania Medical Center, Philadelphia, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Patel HJ, Pilla JJ, Polidori DJ, Pusca SV, Plappert TA, Sutton MS, Lankford EB, Acker MA. Ten weeks of rapid ventricular pacing creates a long-term model of left ventricular dysfunction. J Thorac Cardiovasc Surg 2000; 119:834-41. [PMID: 10733777 DOI: 10.1016/s0022-5223(00)70021-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Rapid ventricular pacing produces a reliable model of heart failure. Cessation after 4 weeks of rapid ventricular pacing results in rapid normalization of left ventricular function, but the left ventricle remains persistently dilated. We present novel data that show that prolonged rapid ventricular pacing (10 weeks) creates a model of chronic left ventricular dysfunction. METHODS In 9 dogs undergoing 10 weeks of rapid ventricular pacing, left ventricular function and volumes were serially assessed by using 2-dimensional echocardiography and pressure-volume analysis for 12 weeks after cessation of pacing. RESULTS Increased end-diastolic volume and decreased systolic and diastolic function were seen at the end of pacing. By 2 weeks of recovery from rapid ventricular pacing, end-diastolic volume and ejection fraction were partially recovered but did not improve further thereafter. Load-independent and load-sensitive indices of function obtained by pressure-volume analysis at 8 and 12 weeks of recovery confirmed a persistence of both systolic and diastolic dysfunction. In addition, left ventricular mass increased with pacing and remained elevated at 8 and 12 weeks of recovery. Four of these dogs studied at 6 months of recovery showed similar left ventricular abnormalities. CONCLUSION Ten weeks of rapid ventricular pacing creates a long-term model of left ventricular dysfunction.
Collapse
Affiliation(s)
- H J Patel
- Divisions of Cardiothoracic Surgery and Cardiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Patel HJ, Belvisi MG, Donnelly LE, Yacoub MH, Chung KF, Mitchell JA. Constitutive expressions of type I NOS in human airway smooth muscle cells: evidence for an antiproliferative role. FASEB J 1999; 13:1810-6. [PMID: 10506584 DOI: 10.1096/fasebj.13.13.1810] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In airway diseases, smooth muscle cells can proliferate at exaggerated rates; thus, the identification of endogenous pathways that limit proliferative responses is important. Here we show that human airway smooth muscle express type I nitric oxide synthase (NOS), which results in inhibition of DNA synthesis and cell proliferation. In addition, superoxide dismutase (SOD), a cell-permeable mimetic that increases the biological half-life and therefore enhances the biological activity of endogenously released nitric oxide (NO), or NO-releasing drugs also greatly reduce DNA synthesis and cell proliferation. Observations in this study have important clinical implications: 1) NOS inhibition may exacerbate airway disease and 2) inhaled SOD/mimetics or NO/nitrovasodilators may be therapies for the treatment of asthma or chronic obliterative pulmonary disease.
Collapse
Affiliation(s)
- H J Patel
- Department of Thoracic Medicine and Cardiothoracic Surgery, Imperial College School of Medicine at the National Heart and Lung Institute, London, SW3 6LY, UK
| | | | | | | | | | | |
Collapse
|
17
|
Patel HJ, Douglas GJ, Herd CM, Spina D, Giembycz MA, Barnes PJ, Belvisi MG, Page CP. Antigen-induced bronchial hyperresponsiveness in the rabbit is not dependent on M(2)-receptor dysfunction. Pulm Pharmacol Ther 1999; 12:245-55. [PMID: 10500004 DOI: 10.1006/pupt.1999.0204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have assessed the effect of sensitization to allergen on airway smooth muscle responsiveness and acetylcholine (ACh) release from cholinergic nerves in tracheal preparations from rabbits immunized at birth to Alternaria tenuis and littermate control rabbits injected with saline. ACh release induced by EFS was significantly greater in tracheal preparations obtained from immunized rabbits compared with littermate controls. The ability of the muscarinic-receptor agonist, oxotremorine, to inhibit ACh release to EFS (4 Hz) was not altered by immunization. The contractile response evoked by electrical field stimulation (EFS), ACh and 5-hydroxytryptamine (5-HT) was not significantly altered in tracheal preparations from antigen immunized rabbits compared with littermate controls. Antigen challenge of immunized rabbits did not affect the release of ACh from isolated trachea following EFS, or the ability of oxotremorine to inhibit ACh release. Furthermore, antigen challenge of immunized rabbits failed to alter the contractile response to EFS or ACh, but reduced the contractile potency of 5-HT. These results demonstrate increased ACh release in tracheal preparations following immunization which had no functional consequence on airway smooth muscle responsiveness. Moreover, the increased release in ACh was not associated with an alteration in M(2)-receptor function. Thus, antigen-induced bronchial hyperresponsiveness in the rabbit does not appear to depend upon M(2)-receptor dysfunction.
Collapse
Affiliation(s)
- H J Patel
- Thoracic Medicine, Imperial College School of Science, Technology and Medicine at the National Heart and Lung Institute, Dovehouse Street, London, SW3 6LY, UK
| | | | | | | | | | | | | | | |
Collapse
|
18
|
Chung KF, Patel HJ, Fadlon EJ, Rousell J, Haddad EB, Jose PJ, Mitchell J, Belvisi M. Induction of eotaxin expression and release from human airway smooth muscle cells by IL-1beta and TNFalpha: effects of IL-10 and corticosteroids. Br J Pharmacol 1999; 127:1145-50. [PMID: 10455260 PMCID: PMC1566131 DOI: 10.1038/sj.bjp.0702660] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Eotaxin is a novel C-C chemokine with selective chemoattractant activity for eosinophils. We determined whether eotaxin could be produced by human airway smooth muscle (HASM) cells in culture and examined its regulation by interleukin-10 (IL-10) and the corticosteroid, dexamethasone. Stimulation of the cells with interleukin-1beta (IL-1beta) or tumour necrosis factor (TNFalpha) each at 10 ng ml(-1) induced the release of eotaxin protein with maximal accumulation by 24 h. Interferon-gamma (IFNgamma) alone at 10 ng ml(-1) had no effect and there was no synergy between these cytokines on the release of eotaxin. Reverse phase high performance liquid chromatographic (HPLC) analysis of supernatents from cells treated with TNFalpha (10 ng ml(-1) for 96 h showed immunoreactivity to eotaxin which eluted with the expected retention time of 34.5-35 min. Both IL-1beta and TNFalpha-induced release of eotaxin was not inhibited by dexamethasone (1 microM), however IL-10 (10 ng ml(-1)) had a significant inhibitory effect. Dexamethasone and IL-10 did not inhibit the induction of eotaxin mRNA induced by IL-1beta or TNFalpha. Thus, human airway smooth muscle cells can release eotaxin and could be an important source of chemokine production during airway inflammatory events.
Collapse
Affiliation(s)
- K F Chung
- Thoracic Medicine, National Heart and Lung Institute, London.
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Patel HJ, Venkatesan P, Halfpenny J, Yacoub MH, Fox A, Barnes PJ, Belvisi MG. Modulation of acetylcholine release from parasympathetic nerves innervating guinea-pig and human trachea by endomorphin-1 and -2. Eur J Pharmacol 1999; 374:21-4. [PMID: 10422636 DOI: 10.1016/s0014-2999(99)00308-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Endomorphin-1 and -2 (mu-opioid receptor agonists) produced a concentration-dependent and naloxone-sensitive inhibition of cholinergic contractile responses in guinea-pig trachea (at 10 microM, 46.1 +/- 8.0% and 33.8 +/- 8.6%, respectively). Endomorphin-1 and -2 also inhibited electrically-evoked acetylcholine release from cholinergic nerves innervating guinea-pig (at 0.1 microM, 41.8 +/- 10.9%; at 1 microM 60.1 +/- 6.3%, respectively) and human trachea (at 10 microM, 76.2 +/- 18.1%, and 77.7 +/- 14.3%, respectively). Naloxone prevented the inhibition by endomorphin-1 and -2 in both guinea-pig and human trachea, suggesting that these peptides can inhibit cholinergic, parasympathetic neurotransmission to the airways via the activation of classical opioid receptors.
Collapse
Affiliation(s)
- H J Patel
- Thoracic Medicine, Imperial College School of Medicine at the National Heart and Lung Institute, London, UK
| | | | | | | | | | | | | |
Collapse
|
20
|
Patel HJ, Pilla JJ, Polidori DJ, Sutton MS, Lankford EB, Acker MA. Long-term dynamic cardiomyoplasty improves chronic and acute myocardial energetics in a model of left ventricular dysfunction. Circulation 1998; 98:II346-51. [PMID: 9852925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
BACKGROUND We present the first long-term evaluation of myocardial energetics after dynamic cardiomyoplasty (CMP) in a model of left ventricular (LV) dysfunction. METHODS AND RESULTS Seventeen dogs underwent rapid ventricular pacing (RVP) to create heart failure. Eight dogs were randomly selected to undergo cardiomyoplasty. All dogs continued RVP for 6 additional weeks, whereas the CMP dogs underwent a simultaneously delivered synchronized muscle wrap conditioning protocol. After termination of RVP at 10 weeks in all dogs, myoplasty dogs continued to receive muscle wrap stimulation until the terminal study. Pressure-volume analysis to assess LV energetics was conducted at baseline and 4 weeks and 3 months after termination of RVP (6 months after baseline). At 6 months, CMP dogs displayed enhanced contractility, lower volumes, and more optimal energetics compared with control animals. Acute muscle wrap stimulation further increased effective contractility and myocardial efficiency compared with unassisted beats. CONCLUSIONS The decrease in NYHA functional class that occurs in patients after dynamic cardiomyoplasty may be secondary to its beneficial effects on long-term myocardial function, volume, and energetics.
Collapse
Affiliation(s)
- H J Patel
- Division of Cardiothoracic Surgery, University of Pennsylvania School of Medicine, Philadelphia, USA
| | | | | | | | | | | |
Collapse
|
21
|
Patel HJ, Pilla JJ, Polidodri DJ, Pusca SV, Plappert TA, St John Sutton M, Lankford EB, Acker MA. Modified rapid ventricular pacing: a chronic model of heart failure for evaluation of new surgical therapies. ASAIO J 1998; 44:799-803. [PMID: 9831088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
Rapid ventricular pacing (RVP) in dogs creates a well characterized model of dilated cardiomyopathy. Standard pacing protocols use RVP at 240-260 beats/min for 2-4 weeks, and result in high mortality rates if continued longer. The authors describe a modification of RVP that results in significant heart failure by 4 weeks, but can be continued for up to 10 weeks with low mortality. Nineteen mongrels underwent RVP at 215 beats/min for 10 weeks. Serial pressure-volume analysis and echocardiography were performed in this model to assess longitudinally changes in left ventricular (LV) function and volumes. The mortality rate was 10%. Significant progressive LV dysfunction with concomitant LV enlargement was observed throughout the pacing period. Finally, norepinephrine levels were elevated at the end of pacing, consistent with an activated sympathetic system. This modified RVP protocol permits long-term pacing with a low mortality rate and results in progressive heart failure throughout the pacing period. This model would be useful in the long-term evaluation of newer surgical and medical therapies of the failing heart.
Collapse
Affiliation(s)
- H J Patel
- Division of Cardiothoracic Surgery, University of Pennsylvania School of Medicine, Philadelphia, USA
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Pusca SV, Pilla JJ, Blom AS, Patel HJ, Dougherty L, Yuan Q, Ferrari VA, Axel L, Acker MA. Determination of global function and regional mechanics of dynamic cardiomyoplasty using magnetic resonance imaging. ASAIO J 1998; 44:M491-5. [PMID: 9804479 DOI: 10.1097/00002480-199809000-00034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
This study used tissue tagged magnetic resonance (MR) to assess regional strain and generate pressure-volume (PV) loops in a canine model of cardiomyoplasty (CMP). Three dogs with rapid ventricular pacing induced heart failure underwent dynamic CMP chronic cardiac assistance for 1 year. At the end of the study period, we performed a MR study with the myostimulator "on" and "off" and recording of left ventricular (LV) pressure. We determined the short axis displacement (D) and maximal and minimal principal strains (lambda1 and lambda2) by quantitative two-dimensional regional spatial modulation of magnetization visualization utility image analysis. LV PV loops were generated by combining the LV volume data from the MR images with the LV pressure recorded during imaging. Muscle stimulation produced a leftward shift of the LV PV loops in two of the three dogs, and an increase in LV peak pressure and dp/dt max. In contrast, short axis lambda1 and lambda2 did not change significantly (p = NS). D increased significantly in the anterolateral, posterolateral, and posteroseptal regions (p < 0.05) but did not change for the septal region (p = NS). Flap stimulation augments LV function in the absence of short axis strain change; this suggests that dynamic CMP exerts its main action along the long axis of the heart.
Collapse
Affiliation(s)
- S V Pusca
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Patel HJ, Giembycz MA, Keeling JE, Barnes PJ, Belvisi MG. Inhibition of cholinergic neurotransmission in guinea pig trachea by NS1619, a putative activator of large-conductance, calcium-activated potassium channels. J Pharmacol Exp Ther 1998; 286:952-8. [PMID: 9694955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Indirect functional studies suggest that large-conductance calcium-activated potassium channels (BKCa channels) are involved in the control of ACh release from postganglionic, parasympathetic nerve terminals in the airways. The role of BKCa channels in regulating cholinergic neurotransmission was assessed by 1) investigating the effect of the putative BKCa channel opener NS1619 on cholinergic contractile responses and ACh output evoked by electrical field stimulation (EFS: 40 V, 0.5 ms, 4 Hz for 15 s every 4 min) and comparing the effect obtained with the inhibition of EFS-evoked ACh release by oxotremorine M, a muscarinic agonist, and 2) evaluating the sensitivity of these responses to the BKCa channel blocker iberiotoxin (IbTX). NS1619 (30 microM) inhibited cholinergic contractile responses by 60.0%. In contrast, NS1619 had no effect on contractile responses evoked by exogenous ACh (1 microM), which indicated that it was acting prejunctionally. NS1619 (30 microM) significantly inhibited EFS-induced ACh release by 33.9%. Oxotremorine M suppressed EFS-evoked ACh release in a concentration-dependent manner (at 1 microM, 77.4% inhibition). In neither case was the inhibition reversed by IbTX (100 nM). Collectively, the mechanical data suggest that NS1619 inhibits cholinergic contractile responses by interacting prejunctionally. The failure of IbTX to reverse the inhibitory action of NS1619 and oxotremorine M on ACh release indicates that activation of muscarinic autoinhibitory receptors is not coupled to the opening of IbTX-sensitive BKCa channels. Therefore, we propose that caution be exercised when using NS1619 as an activator of BKCa channels.
Collapse
Affiliation(s)
- H J Patel
- Thoracic Medicine, Imperial College School of Medicine at the National Heart and Lung Institute, Dovehouse Street, London, England
| | | | | | | | | |
Collapse
|
24
|
Patel HJ, Polidori DJ, Pilla JJ, Plappert T, Kass D, St John Sutton M, Lankford EB, Acker MA. Stabilization of chronic remodeling by asynchronous cardiomyoplasty in dilated cardiomyopathy: effects of a conditioned muscle wrap. Circulation 1997; 96:3665-71. [PMID: 9396469 DOI: 10.1161/01.cir.96.10.3665] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Dynamic cardiomyoplasty is a promising new therapy for dilated cardiomyopathy. The girdling effects of a conditioned muscle wrap alone have recently been postulated to partly explain its mechanism. We investigated this effect in a canine model of chronic dilated cardiomyopathy. METHODS AND RESULTS Twenty dogs underwent rapid ventricular pacing (RVP) for 4 weeks to create a model of dilated cardiomyopathy. Seven dogs were then randomly selected to undergo subsequent cardiomyoplasty, and all dogs had 6 weeks of additional RVP. The cardiomyoplasty group also received 6 weeks of concurrent skeletal muscle stimulation consisting of single twitches delivered asynchronously at 2 Hz to transform the wrap without active assistance. All dogs were studied by pressure-volume analysis and echocardiography at baseline and after 4 and 10 weeks of pacing. Systolic indices, including ejection fraction (EF), end-systolic elastance (Ees), and preload-recruitable stroke work (PRSW) were all increased at 10 weeks in the wrap versus controls (EF, 34.0 versus 27.1, P=.008; Ees, 1.65 versus 1.26, P=.09; PRSW, 35.9 versus 25.5, P=.001). Ventricular volumes, diastolic relaxation, and left ventricular end-diastolic pressures stabilized in the cardiomyoplasty group but continued to deteriorate in controls. Both the end-systolic and end-diastolic pressure-volume relationships shifted farther rightward in controls but remained stable in the cardiomyoplasty group. CONCLUSIONS In addition to potential benefits from active systolic assistance, benefits from dynamic cardiomyoplasty appear to be partially accounted for by the presence of a conditioned muscle wrap alone. This conditioned wrap stabilizes the remodeling process of heart failure, arresting progressive deterioration of systolic and diastolic function.
Collapse
Affiliation(s)
- H J Patel
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Patel HJ, Lankford EB, Polidori DJ, Pilla JJ, Plappert T, St John Sutton MS, Acker MA. Dynamic cardiomyoplasty: its chronic and acute effects on the failing heart. J Thorac Cardiovasc Surg 1997; 114:169-78. [PMID: 9270632 DOI: 10.1016/s0022-5223(97)70141-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVES Dynamic cardiomyoplasty is an alternative therapy for end-stage heart failure. We investigated the mechanisms, both acute and chronic, by which a synchronously stimulated conditioned muscle wrap affects left ventricular function in a chronic canine model of dilated cardiomyopathy. METHODS Nineteen dogs underwent rapid ventricular pacing at a rate of 215 beats/min for 4 weeks to create a model of heart failure. Eight dogs were then randomly selected to undergo cardiomyoplasty, and all dogs received 6 additional weeks of rapid ventricular pacing. The cardiomyoplasty group also received a graded muscle conditioning protocol of synchronized burst stimulation to transform the muscle wrap. All dogs were studied with pressure-volume analysis and echocardiography at baseline and after 4 and 10 weeks of rapid ventricular pacing. Data in the cardiomyoplasty group were analyzed with the stimulator off, with it augmenting every beat (1:1), and with it augmenting only every other beat (1:2). RESULTS Stimulator "of" data at 10 weeks of rapid pacing demonstrated chronic effects by enhanced ventricular function (end-systolic elastance = 1.80 after myoplasty vs 1.17 for controls, p = 0.005) and a stabilization of volumes and composite end-systolic and end-diastolic pressure-volume relations in the cardiomyoplasty group when compared with controls. Myoplasty stimulation increased apparent contractility (preload recruitable stroke work = 31.3 for stimulator "of" vs 40.6 for stimulator 1:2 assisted beats [p < 0.05] and vs 45.4 for stimulator 1:1 [p < 0.05]). CONCLUSIONS Benefits from dynamic cardiomyoplasty are by at least two mechanisms: (1) the girdling effects of a conditioned muscle wrap, which halts the chronic remodeling of heart failure, and (2) active systolic assistance, which augments the apparent contractility of the failing heart.
Collapse
Affiliation(s)
- H J Patel
- Division of Cardiothoracic Surgery, University of Pennsylvania School of Medicine, Philadelphia, USA
| | | | | | | | | | | | | |
Collapse
|
26
|
Patel HJ, Giembycz MA, Spicuzza L, Barnes PJ, Belvisi MG. Naloxone-insensitive inhibition of acetylcholine release from parasympathetic nerves innervating guinea-pig trachea by the novel opioid, nociceptin. Br J Pharmacol 1997; 120:735-6. [PMID: 9138674 PMCID: PMC1564553 DOI: 10.1038/sj.bjp.0701013] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/1996] [Accepted: 12/04/1996] [Indexed: 02/04/2023] Open
Abstract
The novel peptide, nociceptin and the mu-opioid agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO) produced a concentration-dependent inhibition of electrical field stimulation (EFS)-evoked release of acetylcholine (ACh) from cholinergic nerves innervating guinea-pig trachea. The non-selective opioid receptor antagonist, naloxone, did not antagonize the inhibitory action of nociceptin under conditions where the inhibition of ACh release evoked by DAMGO was completely reversed. It is suggested that DAMGO and nociceptin can inhibit cholinergic, parasympathetic neurotransmission to the airways via the activation of classical (naloxone-sensitive) and novel (naloxone-insensitive) opioid receptors, respectively.
Collapse
Affiliation(s)
- H J Patel
- Thoracic Medicine, Imperial College School of Medicine, National Heart & Lung Institute, London
| | | | | | | | | |
Collapse
|
27
|
Belvisi MG, Patel HJ, Takahashi T, Barnes PJ, Giembycz MA. Paradoxical facilitation of acetylcholine release from parasympathetic nerves innervating guinea-pig trachea by isoprenaline. Br J Pharmacol 1996; 117:1413-20. [PMID: 8730733 PMCID: PMC1909463 DOI: 10.1111/j.1476-5381.1996.tb15300.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
1. Previous studies have provided evidence that activation of beta-adrenoceptors on cholinergic nerve terminals can inhibit neurotransmission in the airways. However, in most cases, this conclusion has been based on indirect evidence obtained from mechanical experiments where changes in airways smooth muscle tone were measured. 2. We have assessed whether modulation of cholinergic neurotransmission by beta-adrenoceptor agonists is due to a pre- or post-junctional action by investigating the effect of isoprenaline on contractile responses evoked by exogenous acetylcholine (ACh) and electrical field stimulation (EFS; 4 Hz, 40 V, 0.5 ms pulse width every 15 s), and on EFS-induced ACh release from cholinergic nerves innervating guinea-pig and human trachea. Furthermore, the subtype of beta-adrenoceptor which modulates neurotransmission and the potential role of cyclic AMP in this response were evaluated. 3. In guinea-pig trachea, isoprenaline (1 nM-1 microM) inhibited the contractile response evoked by exogenous ACh (1 microM) to a similar extent to that evoked by EFS (EC50 = 19.9 and 23 nM, respectively). 4. In epithelium-denuded guinea-pig strips treated with indomethacin (10 microM), isoprenaline significantly enhanced EFS-induced ACh release from cholinergic nerve terminals (by 36% at 0.3 microM). This effect was blocked by propranolol and ICI 118, 551 (each 0.1 microM). In contrast, isoprenaline failed to affect EFS-induced ACh release from parasympathetic nerves innervating human trachea. 5. To evaluate the role of cyclic AMP in the beta-adrenoceptor-induced facilitation of cholinergic neurotransmission, the effects of various cyclic AMP elevating drugs on ACh release were studied. Forskolin (10 microM) significantly augmented (by 17%) EFS-induced ACh release, an effect which was not reproduced by 1,9-dideoxyforskolin (10 microM) which does not activate adenylyl cyclase. Similarly, the cyclic AMP analogue, 8-bromo-cyclic AMP (1 mM) and cholera toxin (1 microgram ml-1) facilitated ACh output by 22 and 47% respectively, whereas prostaglandin E2 (PGE2, 0.1 nM-1 microM) inhibited this response (by 67% at 1 microM). 6. Zardaverine (10 microM), a dual inhibitor of the phosphodiesterase (PDE)3 and PDE4 isoenzyme families, did not affect EFS-induced ACh release and failed to facilitate the actions of either isoprenaline or PGE2. Similarly, neither SK&F 94120 (10 microM) nor rolipram (10 microM), selective inhibitors of PDE3 and PDE4 respectively, significantly affected the release of ACh in response to EFS. 7. The result of this study suggests that isoprenaline facilitates cholinergic neurotransmission in guinea-pig, but not human, trachea by activation of pre-junctional beta 2-adrenoceptors, an effect that may be mediated via activation of the cyclic AMP/cyclic AMP-dependent protein kinase cascade. Furthermore, the data presented herein illustrate the need to undertake direct measurements of neurotransmitter release when examining the effect of agents purported to act pre-junctionally.
Collapse
Affiliation(s)
- M G Belvisi
- Department of Thoracic Medicine, Royal Brompton National Heart and Lung Institute, London
| | | | | | | | | |
Collapse
|
28
|
Patel HJ, Barnes PJ, Takahashi T, Tadjkarimi S, Yacoub MH, Belvisi MG. Evidence for prejunctional muscarinic autoreceptors in human and guinea pig trachea. Am J Respir Crit Care Med 1995; 152:872-8. [PMID: 7663798 DOI: 10.1164/ajrccm.152.3.7663798] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Functional studies suggest the presence of prejunctional muscarinic autoreceptors on cholinergic nerves in human airways. However, these studies are an indirect method of evaluating changes in neurally evoked acetylcholine (ACh) release. We have investigated the presence of muscarinic autoreceptors in human and guinea pig trachea by comparing the effects of the muscarinic receptor antagonists pirenzepine (M1), methoctramine (M2), 4-DAMP (M3), and rispenzepine (M1/M3) on cholinergic neural contractile responses evoked by electrical field stimulation (EFS) and [3H]ACh release. The M1, M1/M3, or M3 antagonists inhibited the EFS-evoked cholinergic contractile response in a concentration-dependent manner (4-DAMP > rispenzepine > pirenzepine), whereas methoctramine facilitated this response at low concentrations ( < 3 microM). In ACh release studies, the M3 antagonist had no significant effect, whereas pirenzepine, methoctramine, and rispenzepine significantly increased ACh release in guinea pig trachea. In contrast, ACh release was significantly inhibited by the muscarinic agonist oxotremorine M. Methoctramine and the nonselective antagonist ipratropium bromide, but not the M1, M1/M3, or M3 antagonists, significantly increased ACh release in human trachea. These data suggest the presence of an autoinhibitory receptor on cholinergic nerve terminals in human and guinea pig trachea. In addition, the action of ipratropium bromide at the autoinhibitory receptor may limit its use in the treatment of obstructive airways disease.
Collapse
Affiliation(s)
- H J Patel
- Department of Thoracic Medicine, National Heart and Lung Institute, London, United Kingdom
| | | | | | | | | | | |
Collapse
|
29
|
Rosvoll RV, Mengason AP, Smith L, Patel HJ, Maynard J, Connor F. Visual and automated differential leukocyte counts. A comparison study of three instruments. Am J Clin Pathol 1979; 71:695-703. [PMID: 453086 DOI: 10.1093/ajcp/71.6.695] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The authors compared referee (senior author) microscopic counts, microscopic counts by several technologists, and counts obtained with two pattern-recognition leukocyte classifiers, (1) Larc and (2) Hematrak, and a cytochemical automated method for leukocyte counting, (3) Hermalog D, using samples from (1) a random patient population, (2) a selected abnormal patient population, and (3) healthy individuals. All instruments showed good accuracy and flagged abnormal results for review. Variability in pattern-recognition counts was found to be due mainly to the distribution of the cells on prepared blood smears. The Larc classifier was found to be very sensitive to minor alterations in the cytoplasm or nucleus, and rejected a number of slides. The Hemalog D showed the greatest precision. The method of preparation of slides would be a major decision factor in selecting one pattern-recognition instrument over another.
Collapse
|