Aortic valve replacement through a limited bilateral thoracotomy in a patient with a tracheostoma.
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Aortic Valve↗
Biomedical subjects
C Abad
Publications and source records attributed to C Abad.
Environment- and sequence-dependent modulation of the double-stranded to single-stranded conformational transition of gramicidin A in membranes.
The role of the membrane lipid composition and the individual Trp residues in the conformational rearrangement of gramicidin A along the folding pathway to its channel conformation has been examined in phospholipid bilayers by means of previously described size-exclusion high-performance liquid chromatography HPLC-based strategy (Bañó et al. (1991) Biochemistry 30, 886). It has been demonstrated that the chemical composition of the membrane influences the transition rate of the peptide rearrangement from double-stranded dimers to beta-helical monomers. The chemical modification of Trp residues, or its substitution by the more hydrophobic residues phenylalanine or naphthylalanine, stabilized the double-stranded dimer conformation in model membranes. This effect was more notable as the number of Trp-substituted residues increased (tetra > tri > di > mono), and it was also influenced by the specific position of the substituted amino acid residue in the sequence, in the order Trp-9 approximately Trp-13 > Trp-11 > Trp-15. Moreover, it was verified that nearly a full contingent of indoles (Trp-13, -11, and -9) is necessary to induce a quantitative conversion from double-stranded dimers to single-stranded monomers, although Trp-9 and Trp-13 seemed to be key residues for the stabilization of the beta-helical monomeric conformation of gramicidin A. The conformation adopted for monomeric Trp --> Phe substitution analogues in lipid vesicles resulted in CD spectra similar to the typical single-stranded beta6.3-helical conformation of gramicidin A. However, the Trp --> Phe substitution analogues showed decreased antibiotic activity as the number of Trp decreased.
Amino Acid Sequence↗
Mobilization of potent plasma bactericidal activity during systemic bacterial challenge. Role of group IIA phospholipase A2.
Extracellular mobilization of Group IIA 14-kD phospholipase A2 (PLA2) in glycogen-induced rabbit inflammatory peritoneal exudates is responsible for the potent bactericidal activity of the inflammatory fluid toward Staphylococcus aureus (1996. J. Clin. Invest. 97:250-257). Because similar levels of PLA2 are induced in plasma during systemic inflammation, we have tested whether this gives rise to plasma bactericidal activity not present in resting animals. Baboons were injected intravenously (i.v.) with a lethal dose of Escherichia coli and plasma or serum was collected before and at hourly intervals after injection. After infusion of bacteria, PLA2 levels in plasma and serum rose > 100-fold over 24 h to approximately 1 microg PLA2/ml. Serum collected at 24 h possessed potent bactericidal activity toward S. aureus, Streptococcus pyogenes, and encapsulated E. coli not exhibited by serum collected from unchallenged animals. Bactericidal activity toward S. aureus and S. pyogenes was nearly completely blocked by a monoclonal antibody to human Group IIA PLA2 and addition of purified human Group IIA PLA2 to prechallenge serum conferred potent antistaphylococcal and antistreptococcal activity equal to that of the 24 h post-challenge serum. PLA2-dependent bactericidal activity was enhanced approximately 10x by factor(s) present constitutively in serum or plasma. Bactericidal activity toward encapsulated E. coli was accompanied by extensive bacterial phospholipid degradation mediated, at least in part, by the mobilized Group IIA PLA2 but depended on the action of other bactericidal factors in the 24-h serum. These findings further demonstrate the contribution of Group IIA PLA2 to the antibacterial potency of biological fluids and suggest that mobilization of this enzyme during inflammation may play an important role in host defense against invading bacteria.
Animals↗
[Cardiac tumors. I. General considerations. Benign primary tumors].
With the widespread use of echocardiography, cardiac tumors are no longer a rare disease. They are increasingly being diagnosed and surgically treated. In this review we present a practical classification of heart tumors, most common symptoms, diagnostic methods and guidelines for surgical treatment. Benign cardiac tumors are described specially in reference to pathology and surgical treatment. Cardiac myxomas are more extensively deal with.
Diagnosis, Differential↗
[Cardiac tumors (II). Malignant primary tumors. Metastatic tumors. Carcinoid tumor].
Heart neoplasms are of increasing interest among clinicians and surgeons. A review of primary malignant cardiac tumors, secondary cardiac tumors and carcinoid heart tumors is presented, with special reference to their pathological and surgical aspects. Primary malignant heart tumors represent about 25% of all cardiac tumors, the great majority are sarcomas and the whole family of this group is described including angiosarcoma, rhabdomyosarcoma, fibrosarcoma, leiomyosarcoma, liposarcoma, neurogenic sarcoma, synovial sarcoma and osteosarcoma; mesothelioma, lymphoma, malignant teratoma and thymoma are also included. Metastatic heart tumors are 20-40 times more common than primary malignancies, their behavior and more relevant aspects in diagnostic and surgical therapy are mentioned. Carcinoid heart tumors represent a distinctive entity and are discussed individually.
Carcinoid Tumor↗
Structural characterisation of the natural membrane-bound state of melittin: a fluorescence study of a dansylated analogue.
The binding of a dansylated analogue of melittin (DNC-melittin) to natural membranes is described. The cytolytic peptide from honey bee venom melittin was enzymatically labelled in its glutamine-25 with the fluorescent probe monodansylcadaverine using guinea pig liver transglutaminase. The labelled peptide was characterised functionally in cytolytic assays, and spectroscopically by circular dichroism and fluorescence. The behaviour of DNC-melittin was, in all respects, indistinguishable from that of the naturally occurring peptide. We used resonance energy transfer to measure the state of aggregation of melittin on the membrane plane in synthetic and natural lipid bilayers. When bound to erythrocyte ghost membranes, the extent of energy transfer was found to be equivalent to when bound to small unilamellar vesicles of phosphatidylcholine. Our results correlate best with a proposed model in which the initial interaction between melittin and the red blood cells could be merely electrostatic and the peptide remains in a low alpha-helical conformation. The next step would be a peptide stabilisation in the membrane in a monomeric alpha-helical conformation that would imply the collapse of the membrane structure and liberation of the cell contents.
Animals↗
A fluorescence spectroscopy study of the interaction of monocationic quinine with phospholipid vesicles. Effect of the ionic strength and lipid composition.
The interaction of monocationic quinine with zwitterionic dimyristoyl phosphatidylcholine (DMPC) and mixed negatively-charged dimyristoylphosphatidyl glycerol (DMPG)/DMPC small unilamellar vesicles in the liquid-crystalline phase was investigated by steady-state fluorescence spectroscopy at pH 7 and 37 degrees C. The maximum fluorescence emission peak at 383 nm, upon excitation at 335 nm, shifts to lower wavelength and decreases its intensity as the ratio between the total lipid and quinine concentrations increases. This indicates that in the membrane-bound state quinine is in an environment of low polarity, more deeply buried when anionic DMPG is present in the vesicle. For monoprotonated quinine/DMPC system the corresponding association isotherms show that the extension of binding is slightly enhanced as the ionic strength decreases, whereas for mixed DMPG/DMPC vesicles at low ionic strength, the association of the drug is favoured as the percentage of anionic DMPG increases. The binding curves have been quantitatively analyzed by the binding and the partition models including in this latter an activity coefficient, gamma, to account for non ideal quinine interactions. It is demonstrated for both neutral and anionic membranes that the activity coefficient approaches the unity and that the deviation from ideality is mainly due to electrostatic forces.
Benzoquinones↗
Binding of basic amphipathic peptides to neutral phospholipid membranes: a thermodynamic study applied to dansyl-labeled melittin and substance P analogues.
A thermodynamic approach is proposed to quantitatively analyze the binding isotherms of peptides to model membranes as a function of one adjustable parameter, the actual peptide charge in solution z(p)+. The main features of this approach are a theoretical expression for the partition coefficient calculated from the molar free energies of the peptide in the aqueous and lipid phases, an equation proposed by S. Stankowski [(1991) Biophysical Journal, Vol. 60, p. 341] to evaluate the activity coefficient of the peptide in the lipid phase, and the Debye-Hückel equation that quantifies the activity coefficient of the peptide in the aqueous phase. To assess the validity of this approach we have studied, by means of steady-state fluorescence spectroscopy, the interaction of basic amphipathic peptides such as melittin and its dansylcadaverine analogue (DNC-melittin), as well as a new fluorescent analogue of substance P, SP (DNC-SP) with neutral phospholipid membranes. A consistent quantitative analysis of each binding curve was achieved. The z(p)+ values obtained were always found to be lower than the physical charge of the peptide. These z(p)+ values can be rationalized by considering that the peptide charged groups are strongly associated with counterions in buffer solution at a given ionic strength. The partition coefficients theoretically derived using the z(p)+ values were in agreement with those deduced from the Gouy-Chapman formalism. Ultimately, from the z(p)+ values the molar free energies for the free and lipid-bound states of the peptides have been calculated.
Amino Acid Sequence↗
Effect of physical protection on the mesothelial integrity of the pericardium.
BACKGROUND: Mesothelial integrity is essential for the prevention of pericardial adhesions. This study was performed to determine the effect of physical protection of the pericardium on mesothelial integrity. METHODS: A pericardial biopsy specimen was obtained at the time of pericardiotomy (0 minutes) in 10 patients undergoing a cardiac operation for the first time. The left free edge of the pericardiotomy was plicated inward to protect the mesothelium. Biopsy specimens were obtained from the protected and unprotected pericardium at 45 and 90 minutes after the start of extracorporeal circulation. Mesothelial integrity and the local inflammatory response were then assessed and graded histologically. RESULTS: The mesothelium was found to be present in the protected specimens at 0, 45, and 90 minutes, but it was found to be denuded in the unprotected specimens (p = 0.003 at 45 minutes; p = 0.004 at 90 minutes). Local inflammation was totally established in both the protected and unprotected specimens at 45 minutes. CONCLUSIONS: Physical agents appear to be the main factor that is damaging to the pericardial mesothelium, and this is an important concept to be taken into consideration when designing a method to prevent pericardial adhesions.
Adult↗
Experience with the use of polytetrafluoroethylene pericardial membrane (preclude pericardial membrane) for retroperitoneal closure after abdominal aortic surgery.
OBJECTIVE: The purpose of the present publication is to assess the outcome after closure of the retroperitoneum with a patch of polytetrafluorethylene surgical membrane (Preclude Pericardial Membrane. PPM) after abdominal aortic surgery. EXPERIMENTAL DESIGN: Retrospective review of 7 operated patients with a patch of PPM covering their abdominal aortic synthetic graft. Twenty-five months of follow up. SETTING: Institutional and University Hospital. PATIENTS AND PARTICIPANTS: Between June 1993 and February 1995, in 7 consecutive male patients (mean age 62 years) a patch of PPM was applied to their retroperitoneum after undergoing surgery in their infrarenal abdominal aorta. One patient had total obliteration of the distal abdominal aorta (Leriche syndrome) and the remaining 6 had a small infrarenal abdominal aortic aneurysm measuring in transverse diameter between 4 and 5 centimetres. INTERVENTIONS: The patient with Leriche Syndrome had an end to end aorto bifemoral bypass graft and the 6 cases with abdominal aortic aneurysm underwent resection of the aneurysm plus interposition of a straight vascular graft (3 cases), straight vascular graft and extension with other graft to the femoral artery (1 case) and bifurcated aorto-bifemoral graft (2 cases). MEASURES: Clinical outcome and evolution of the patients, absence of complications derived from the PPM. RESULTS: There was no hospital mortality. All patients are alive after a mean follow-up of 25 months. Two patients were reoperated in the early postoperative period, one of them required a limited resection of the jejunum. There have been no complications related to the PPM. CONCLUSIONS: In order to avoid secondary aorto-intestinal fistulas, in cases where complete coverage and isolation of an artificial vascular graft in the abdominal aorta can not be achieved, the use of a sheet of PPM separating the arterial graft from the gastrointestinal system may be an useful alternative.
Adult↗
Long-term clinical performance of Sorin tilting-disc mechanical prostheses in the mitral and aortic position.
OBJECTIVE: Analyzing the long term performance of sorin tilting-disc mechanical prostheses. EXPERIMENTAL DESIGN: Retrospective patient-oriented study. The total follow-up was 460.2 patient-years. Follow-up data was obtained from the patients themselves or from their relatives. SETTING: Department of Cardiovascular Surgery in a general community hospital. PATIENTS: Seventy four patients undergoing valve replacement with Sorin tilting-disc mechanical prostheses between May, 1982 and July 1991. INTERVENTIONS: Thirty one of those patients underwent isolated mitral valve replacement (MVR) and 43 isolated aortic valve replacement (AVR). MEASURES: The incidence of the different complications is expressed as linearized rates. Actuarial analysis was performed with the Kaplan-Meier method. RESULTS: Linearized rates for MVR and AVR for the different complications (events per 100 patient-years) were, respectively: Late mortality: 4.5 +/- 1.6 and 1.8 +/- 0.8; Thromboembolism: 3.4 +/- 1.4 and 1.1 +/- 0.6; Anticoagulant-related hemorrhage: 2.8 +/- 1.3 and 0.3 +/- 0.3; Prosthetic endocarditis: 1.1 +/- 0.8 and 0.7 +/- 0.5; Non-structural dysfunction: 0.5 +/- 0.5 and 1.1 +/- 0.6; Reoperation: 1.1 +/- 0.8 and 0.3 +/- 0.3. Actuarial probabilities of freedom from the different complications were, respectively, at 13 years follow-up for MVR and 12 years follow-up for AVR, the following: Late mortality: 45.7 +/- 12.4% and 70.3 +/- 7.9%; Thromboembolism: 74.6 +/- 10.8% and 90.7 +/- 5.1%; Anticoagulant-related hemorrhage: 79.4 +/- 11.6% and 97.3 +/- 2.7%; Prosthetic endocarditis: 92.7 +/- 4.9% and 91.2 +/- 6.4%; Non-structural dysfunction: 95.6 +/- 4.3% and 88.2 +/- 6.6%; Reoperation: 83.6 +/- 11.8% and 97.3 +/- 2.7%. All valve-related mortality and morbidity: 42.2 +/- 11.0% and 56.7 +/- 8.6%. There was no instances of prosthetic structural failure. CONCLUSIONS: The Sorin mechanical prosthesis presents a good durability and its performance in the long term is comparable to other tilting-disc devices of the same generation.
Actuarial Analysis↗
[Cardiac tamponade as first clinical manifestation of small cell carcinoma].
A 69 year old man was diagnosed of cardiac tamponade. At surgery a large hemopericardias was evacuated, cardiac and pericardial metastasis of an oat cell carcinoma was demonstrated. The patient died 4 weeks later. A review of the literature is done about patients with cardiac tamponade as the first manifestation of a neoplastic process.
Carcinoma, Small Cell↗
Core histones are glutaminyl substrates for tissue transglutaminase.
Chicken erythrocyte core histones are glutaminyl substrates in the transglutaminase (TGase) reaction with monodansylcadaverine (DNC) as donor amine. The modification is very fast when compared with that of many native substrates of TGase. Out of the 18 glutamines of the four histones, nine (namely glutamine 95 of H2B; glutamines 5, 19, and 125 of H3; glutamines 27 and 93 of H4; and glutamines 24, 104, and 112 of H2A) are the amine acceptors in free histones. The use of Gln112 of H2A requires a temperature-dependent partial unfolding of the histone, showing that structural determinants are decisive for the glutamine specificity. The structures of H2A and H2B do not appreciably change upon modification with DNC as determined by circular dichroism, and core particles reconstituted from these DNC-modified histones are indistinguishable from native nucleosome cores. When the reaction is carried out with native nucleosomes, only glutamines 5 and 19 of H3, which are located in the N-terminal tail, and glutamine 22 of H2B, which is not labeled in free histone, are modified. Methylamine and putrescine also are incorporated into nucleosomes by the TGase reaction. Our results reveal several possibilities for the application of the TGase reaction in the chromatin field, and taking into account that histones are easily cross-linked or modified by polyamines in vitro, the possibility that they may be TGase substrates in vivo is discussed.
Amino Acid Sequence↗
[Purulent abscess myocarditis with fatal outcome, caused by Streptococcus agalactiae].
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Abscess↗
Cutaneous mucormycosis of the thoracic wall.
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Aged↗
Pericardial cyst. Surgical resection in two symptomatic cases.
Two cases of surgical resection of symptomatic pericardial cysts are reported. Pathological aspects, diagnostic methods and alternatives of management in these benign lesions are discussed. Other excised cases are also mentioned. The authors recommend excision of these cysts in all patients with a low risk in order to: 1) eliminate the tumour mass, 2) relieve symptoms and 3) allow histological examination.
Adolescent↗
Inflammatory extracavitary right atrial mass and pulmonary thromboembolism.
A 40 year old male patient diagnosed as having pulmonary thromboembolism, was found to have a right atrial mass, after being subjected to an echocardiogram, a CT thoracic Scan and magnetic resonance imaging. An intracardiac exploration by cardiopul-monary bypass was performed. The mass was located and excised, but in fact found to be an extracardiac, inflammatory and cavitated mass. The wall of the right atrium was infiltrated due to the inflammatory process. This case illustrates the advantage of echocardiography, followed by surgery, in the clinical diagnosis and also shows how to treat cardiac masses and tumors.
Adult↗
Massive hemoptysis as a manifestation of fistulized thoracic aortic aneurysms into the bronchial tree.
Aortobronchial fistulas are an uncommon and serious cause of hemoptysis. We present three cases of aortobronchial fistulas that were diagnosed and treated at our hospital. They were presented as massive hemoptysis. The clinical suspicion of a leaking thoracic aortic aneurysm into the bronchial tree should prompt the correct diagnostic procedures since early surgery is the only way to manage this condition.
Aged↗