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[Surgical treatment of tuberculosis and its modifications--collapse therapy and resection treatment and their present-day sequelae].

Surgical treatment of tuberculosis is now largely a thing of the past. After it had been realized that a tuberculous lung process can be cured by shrinkage, i.e. by reducing the volume of both the lung and the thorax, attempts were made to actively promote such shrinkage processes by means of suitable measures. The so-called collapse therapy was initiated by the Italian physician Forlanini in 1888. By pumping air into the free cavity of the pleura the diseased lung as brought into a state of dosed collapse so that infiltrative and cavernous processes could heal with scar formation. However, application of a pneumothorax was prevented by pleural processes that occurred frequently during the course of a disease, especially also as sequels to pleuritis. The operative alternative was an attempt to achieve lung collapse by surgery. Thus the idea was born to enable lung collapse by mobilising the external thoracic wall, i. e. by means of rib resection: this principle was known as thoracoplasty. A little later, attempts were made to circumvent such a crippling intervention by surgically detaching the lung "on target" over the diseased area and by filling the cavity created in this manner, with air to produce a so-called "extrapleural pneumothorax". Lung surgery advanced rapidly after intubation anaesthesia developed since 1945. It was now possible to remove isolated diseased parts of the lung, so that the collapse therapy receded more and more to the background. Side by side with this development of new surgical procedures drug treatment of tuberculosis made rapid progress.(ABSTRACT TRUNCATED AT 250 WORDS)

Antitubercular Agents↗
PubMed1996

Nasal valve suspension. An effective treatment for nasal valve collapse.

OBJECTIVE: To evaluate a new operative technique for treating nasal valve collapse for safety and effectiveness. DESIGN: A nonrandomized pilot study of patients with complaints of nasal airway obstruction, a positive Cottle maneuver, and clinical findings of nasal valve collapse. Follow-up ranged from 1 to 20 months. SETTING: Academic medical center, including a Veterans Affairs hospital. PATIENTS: Twelve men aged 38 to 73 years (mean age, 59.3 years). MAIN OUTCOME MEASURES: Subjective self-assessment scores for nasal airflow were collected on a 10-point scale. Anterior rhinomanometry, acoustic rhinometry, and photographic analysis provided objective data. INTERVENTION: The procedure involves accessing the orbital rim by a transconjunctival incision, then passing sutures from the nose to this incision where they may be affixed to the orbital rim. The collapsing tissue of the nasal valve is thus supported and collapse is prevented. RESULTS: All patients reported immediate subjective improvement in their symptoms of nasal obstruction; this was reflected in their self-assessment scores. The rhinomanometry showed reduced nasal resistance in 10 (83%) of 12 patients. The acoustic rhinometry showed an increase in minimum cross-sectional area in 2 (33%) of 6 patients, with the others remaining stable. The photographic analysis revealed mild widening of the mid-third of the nose in 6 of 12 patients, although this was not of concern to the patients. There were no major complications. CONCLUSION: Nasal valve suspension is a safe and effective procedure for treatment of nasal valve collapse.

Adult↗
PubMed1996

Exogenous nitric oxide causes collapse of retinal ganglion cell axonal growth cones in vitro.

We show that nitric oxide (NO) from applied NO-donating chemicals induces collapse of ganglion cell axonal growth cones extending from explants of tadpole retina in culture. Peroxynitrite, a neurotoxic product of NO and superoxide reaction, did not induce collapse, and oxyhemoglobin, which binds NO, blocked the highly effective collapsing activity of the NO donor S-nitrosocysteine. Membrane-permeable analogs of cyclic guanosine monophosphate had no collapsing activity. Inhibitors of NO synthase did not induce collapse. NO is a potential retrograde messenger through which postsynaptic neurons signal to their inputs to modify synaptic efficacy following NMDA receptor activation. Our results suggest a role for NO as such a messenger during development of the retinotectal projection.

Animals↗
PubMed2004

AFM observation of collapse and expansion of phosphoric acid-demineralized dentin.

The objective of this study is to provide additional data regarding morphological changes that occur to dentin matrices following demineralization with etchants. Our understanding of the mechanism of diffusion of comonomers into the demineralized substrate is very limited. It has been hypothesized that certain water-soluble polyelectrolytes (acidic proteins) and neutral proteins in dentin can influence the collapse of demineralized dentin when it is air dried. Some of these solubilized substances are thought to aggregate by the action of Ca cations, which become dissolved during H(3)PO(4) etching, ultimately resulting in some degree of collapse. In the current study, dentin surfaces were examined by atomic force microscopy (AFM) before and after treatment by 10% H(3)PO(4)containing increasing concentrations of CaHPO(4). Reversal of matrix collapse by aqueous 30% 2-hydroxyethyl methacrylate (HEMA) was evaluated by AMF for 60 min. The results demonstrate two forms of matrix collapse; we speculate that one form is induced by acidic noncollagenous polyelectrolytes and the other by neutral peptides. Our data indicate that further evaluation of the influence of endogenous noncollagenous proteins must be studied to understand the mechanism of the collapse and reexpansion dynamics of demineralized dentin networks.

Animals↗
PubMed1998

Kinetics of lysozyme refolding: structural characterization of a non-specifically collapsed state using time-resolved X-ray scattering.

We report time-resolved small angle X-ray scattering (SAXS) studies of the structural characteristics of the collapsed state of lysozyme from henegg white (HEL) obtained on initiating refolding by rapidly changing solvent conditions from 8 M to 1.1 M urea at pH 2.9. At this reduced pH the lifetime, of about one second, of the non-specifically collapsed ensemble is considerably prolonged relative to its value at pH 5.2. The SAXS studies are combined with time resolved measurements of tryptophan fluorescence and of the rate of formation of native molecules using interrupted refolding experiments. We observe large burst phase changes in intrinsic tryptophan fluorescence and in the radius of gyration (Rg) which is reduced from 22 A in the fully unfolded state to approximately 19 to 20 A. Subsequent decrease of the Rg to the value for native lysozyme (15 A) follows the time course of formation of native molecules. Single exponential fits to the singular value decomposition (SVD) components of the SAXS data allow reconstruction of the SAXS profile at early time points of refolding. The results of this analysis suggest a globular shape of the collapsed state. A similar fit to the forward scattering amplitude, I(0), suggests that the collapsed state has a solvent accessible surface area which is considerably increased relative to that of the native protein. These results show directly that the non-specifically collapsed state formed during the burst phase in lysozyme refolding indeed represents a molecular compaction and a change in shape from a fully denatured random coil state (albeit restricted by disulfide bonds) to an ensemble of globular conformations which, however, have not yet formed a solvent-protected hydrophobic core.

Animals↗
PubMed1998

Lattice models for proteins reveal multiple folding nuclei for nucleation-collapse mechanism.

The nature of the nucleation-collapse mechanism in protein folding is probed using 27-mer and 36-mer lattice models. Three different forms for the interaction potentials are used. Three of the four 27-mer sequences have maximally compact and identical native state while the other has a non-compact native conformation. All the sequences fold thermodynamically and kinetically by a two-state process. Analysis of individual trajectories for each sequence using a self-organizing neural net algorithm shows that upon formation of a critical set of contacts the polypeptide chain rapidly reaches the native conformation which is consistent with a nucleation-collapse mechanism. The algorithm, which reduces the identification of the folding nucleus for each trajectory to one of pattern recognition, is used to show that there are multiple folding nuclei. There is a distribution of nucleation contacts in the transition states with some of them occurring with more probability (when averaged over the denatured ensemble) than others. We also show that there is a distribution in the size of the nuclei with the average number of residues in the folding nuclei being less than about one-third of the chain size. The fluctuations in the sizes of the nuclei are large, suggestive of a broad transition region. The folding nuclei, the structures of each are the corresponding transition states, have varying degree of overlap with the native conformation. The distribution of the radius of gyration of the transition states shows that these structures are an expanded form (by about 25% in the radius of gyration) of the native conformation. Local contacts are most dominant in the folding nuclei while a certain fraction of non-local contacts is necessary to stabilize the transition states. The search for the critical nuclei initially involves the formation of local contacts, while non-local contacts are formed later. The fractional values of PhiF for the two 27-mer mutants found by using the protein engineering protocol are consistent with the microscopic picture of partial formation of structures involving these residues in the transition state. These observations lead to a multiple folding nuclei (MFN) model for nucleation-collapse mechanism in protein folding. The major implication of the MFN model is that, even if the residues whose tertiary interactions are formed nearly completely in the transition state are mutated, it does not disrupt the nature of the nucleation-collapse mechanism. We analyze the experiments on chymotrypsin inhibitor 2 and alpha-spectrin SH3 domain and two circular permutants in light of the MFN model. It is shown that the PhiF-value analysis for these proteins gives considerable support to the MFN model. The theoretical and experimental studies give a coherent picture of the nucleation-collapse mechanism in which there is a distribution of folding nuclei with some more probable than others. The formation of any specific nucleus is not necessary for efficient two-state folding.

Alanine↗
PubMed2004

Superior vena caval collapsibility as a gauge of volume status in ventilated septic patients.

OBJECTIVE: In mechanically ventilated patients inspiratory increase in pleural pressure during lung inflation may produce complete or partial collapse of the superior vena cava. Occurrence of this collapse suggests that at this time external pressure exerted by the thoracic cavity on the superior vena cava is greater than the venous pressure required to maintain the vessel fully open. We tested the hypothesis that measurement of superior vena caval collapsibility would reveal the need for volume expansion in a given septic patient. DESIGN AND SETTING: Prospective data collection for 66 successive patients in septic shock admitted in a medical intensive care unit and mechanically ventilated for an associated acute lung injury. MEASUREMENTS AND RESULTS: We simultaneously measured superior vena caval collapsibility by echocardiography and cardiac index by the Doppler technique at baseline and after a 10 ml/kg volume expansion by 6% hydroxyethyl starch in 30 min. The threshold superior vena caval collapsibility of 36%, calculated as (maximum diameter on expiration-minimum diameter on inspiration)/maximum diameter on expiration, allowed discrimination between responders (defined by an increase in cardiac index of at least 11% induced by volume expansion) and nonresponders, with a sensitivity of 90% and a specificity of 100%. CONCLUSIONS: Superior vena cava measurement should be systematically performed during routine echocardiography in septic shock as it gives an accurate index of fluid responsiveness.

Adult↗
PubMed1986

Usefulness of right ventricular diastolic collapse in diagnosing cardiac tamponade and comparison to pulsus paradoxus.

To compare the sensitivity, specificity and predictive value of right ventricular (RV) diastolic collapse and pulsus paradoxus as signs of cardiac tamponade, 21 consecutive patients with pericardial effusion and suspected cardiac tamponade underwent prospective hemodynamic and echocardiographic evaluation. Simultaneous hemodynamic and echocardiographic data were obtained in all patients before and after pericardiocentesis. Cardiac tamponade was considered present when there was diastolic equilibration of the intrapericardial, right atrial and pulmonary capillary wedge pressures and elevation of these pressures to more than 10 mm Hg. RV diastolic collapse was 93% sensitive and 100% specific in diagnosing cardiac tamponade, whereas pulsus paradoxus was only 79% sensitive and 40% specific. The positive and negative predictive values of RV diastolic collapse (100% and 83%) were considerably better than pulsus paradoxus (81% and 40%) and demonstrate that RV diastolic collapse is more sensitive, specific and predictive of cardiac tamponade than is pulsus paradoxus. Serial simultaneous hemodynamic and echocardiographic observations at multiple points during pericardiocentesis in a smaller subgroup (5 patients) also suggest that the hemodynamic effects of RV diastolic collapse in cardiac tamponade are mediated by an increase in intrapericardial pressure.

Adult↗
PubMed1984

Collapse and viscoelasticity of diseased human arteries.

A laboratory study of the hydrostatic collapse of diseased tibial arteries demonstrated hysteresis in the pressure-flow behaviour which resembled that seen in the stress-strain relations of the arterial tissue. The pressures at which the vessels collapsed were found to be considerably lower than expected on the basis of theoretical elastic models. Also, the pressures at which the vessels reopened were consistently lower than the pressures at which they collapsed. These findings were explained on the basis of viscoelasticity. The difference between collapse and opening pressure may provide insight into the mechanical properties of vessels, and a clue to errors in non-invasive measurements of blood pressure which depend upon collapse of arteries.

Aged↗
PubMed1989

Effect of hypercapnia on upper airway resistance and collapsibility in anesthetized dogs.

The upper airway (UAW) is intrinsically unstable and susceptible to collapse when the negative inspiratory intraluminal pressure exceeds the stabilizing forces which prevent obstruction. In the present study we evaluated mechanisms by which UAW patency is maintained in the presence of increased inspiratory flows when respiration is stimulated. In seven anesthetized dogs breathing spontaneously through a low tracheostomy, the UAW was isolated by a second tracheostomy directed rostrally. UAW pressure-flow relationship and stability against collapse were evaluated during steady flow in the inspiratory direction while the animals were breathing 100% O2 or a hypercapnic gas mixture. The pressure-flow curves of the isolated UAW demonstrated the characteristic pattern of collapsible tubes. Steady state hypercapnia resulted in lower UAW resistance during both inspiration and expiration. UAW resistance decreased linearly as PCO2 and ventilation increased over the course of CO2 rebreathing. In addition, during hypercapnia the critical negative intraluminal pressure required to induce UAW collapse and obstruction increased from -4.3 +/- 0.9 to -8.5 +/- 1.5 SE cm H2O (p less than 0.01), indicating increased stability of the UAW. Since hypercapnia is known to stimulate UAW muscles, our findings suggest that increased UAW muscle activity improves UAW patency both by decreasing their resistance to airflow, and by increasing UAW walls rigidity and stability against collapse.

Airway Resistance↗
PubMed2004

Endoscopic KTP laser excision of severe tracheotomy-associated suprastomal collapse.

OBJECTIVE: The purpose of this study was to investigate the feasibility, safety, and clinical utility of potassium-titanium-phosphate (KTP) laser bronchoscopy for excision of severe, obstructing tracheotomy-associated suprastomal collapse. METHODS: A retrospective review was performed of six children at a tertiary care children's hospital with severe tracheotomy-associated collapse of the suprastomal anterior tracheal wall cartilage, precluding decannulation. All subjects had undergone KTP laser endoscopic excision of the collapsed segment of suprastomal tracheal cartilage. Medical records were assessed for: (1) endoscopic demonstration of relief of suprastomal collapse, and (2) successful tracheotomy decannulation. RESULTS: All six patients had endoscopic evidence of relief of suprastomal airway obstruction after KTP laser therapy. Five of six (83%) subsequently underwent successful decannulation. There was one case of minimal thermal airway injury associated with a laser fire during use of the KTP laser, the effects of which were fortunately transient. CONCLUSIONS: KTP laser bronchoscopic excision of severe tracheotomy-associated suprastomal collapse: (1) is a feasible technique; (2) results in relief of suprastomal obstruction with subsequent successful decannulation in selected patients; and (3) avoids the need for more extensive open neck procedures. However, risks of KTP laser therapy are not negligible and strategies must be in place to minimize the occurrence of complications.

Bronchoscopy↗
PubMed2004

Alveolar septal collapse in the transitional infant lung: a possible common mechanism in sudden unexpected death in infancy.

Sudden unexpected death in infancy (SUDI) is a category used to represent the largest single group of infant deaths. Although there are several theories, the cause of SUDI remains unknown and the mechanism of co-sleeping associated deaths are also undetermined. We investigate a possible biomechanical mechanism which may be common in SUDI and may provide an explanation for the association of the known risk factors for SUDI such as co-sleeping, prematurity, prone sleeping position, overwrapping, overheating and maternal smoking. The neonatal lung has few, if any, true septa but from about four weeks of age, a period of rapid alveolarisation commences. The developing alveolar walls (septae) have little fibre support against surface tension forces as they grow but are supported by a double layer of capillaries. Until the elastin/collagen supporting network is laid down these nascent septal walls are vulnerable to collapse against sac or duct walls during this transitional period. We hypothesise that such collapse will prevent one side of the septa, and the wall it overlays, from alveolar gas exchange and a functional left-right shunt is formed which may result in hypoxia. Furthermore, lung stretch receptors in bronchi running through or adjacent to collapsed regions will be activated, falsely signalling lung inflation to the brain stem with resultant respiratory inhibition, so precipitating further collapse. The process will continue until lung volume falls below residual capacity, when normal tidal breathing efforts will no longer result in significant air flow, even if stretch receptor signals have not produced complete apnoea. Large inspiratory efforts are then required to break the surface tension seal, which damages capillaries to produce petechial haemorrhages. Many epidemiological risk factors for SUDI could influence such a mechanism, leading to the proposal that Alveolar Septal Collapse in Infancy (ASCI) is a core mechanism via which these factors act.

Airway Obstruction↗
PubMed2005

Morphology and chain dynamics during collapse transition of PNIPAM gels studied by combined imaging, relaxometry and 129Xe spectroscopy techniques.

The temperature-induced shape transition of poly(N-isopropylacrylamide) gels of different cross-link densities was investigated by a combination of NMR techniques allowing the characterization of both the macroscopic collapse as well as the changes on a molecular scale related to the expulsion of water from the gel network. The proton-containing gel phase was visualized by swelling in heavy water, and the volume change was monitored by proton imaging for cross-link densities between 0.5% and 2.5%. Above the transition temperature of 35 degrees C, gel collapse led to a volume change of up to a factor of 17 for the gel of smallest cross-link density. Two spectral lines of 129Xe are found in the gel state and are assigned to the hydrophobic and hydrophilic parts of the network. In the collapsed state, the hydrophobic peak shows a strong shift while the hydrophilic peak disappears. A considerable shortening of both T1 and T2 of the gel protons upon collapse was found at a field of 4.7 T. At lower fields, the effect becomes more pronounced and qualitatively different dispersion behaviors between the swollen and the collapsed states are observed.

Acrylic Resins↗
PubMed2005

Cartilage degeneration in post-collapse cases of osteonecrosis of the human femoral head: altered mechanical properties in tension, compression, and shear.

Osteonecrosis, or avascular necrosis, is a painful and debilitating condition characterized by progressive joint degeneration subsequent to collapse of necrotic regions of trabecular bone. A clear understanding of the mechanism of cartilage degeneration in osteonecrosis is critical to the development of treatment strategies aimed at sparing the femoral head. An analysis of 13 post-collapse osteonecrotic (ON) human femoral heads was performed relative to 24 non-ON controls to determine quantitatively the biomechanical and histological properties of post-collapse osteonecrotic cartilage. Cartilage mechanical properties were measured in tension, compression, and shear at different sites on the femoral head and correlated to histologic measures of cartilage degeneration using a semi-quantitative grading scale. Decreasing cartilage tensile strength correlated with histologic evidence of degeneration in the ON group; however, less correlation was noted with shear and compressive properties. After statistical correction for the more severe histologic degeneration in the ON group, the non-ON samples were found to exhibit significantly smaller loss angles during shear testing, while samples from the ON group were found to have greater tensile strength. Similarly, the ON group was found to exhibit significantly greater proteoglycan loss while the non-ON group showed significantly increased surface fibrillation. This study provides evidence that the changes occurring in post-collapse cases of osteonecrosis may involve mechanisms other than those typically attributed to osteoarthritic degeneration. One potential explanation is that decreased loading of cartilage overlying collapsed ON lesions leads to proteoglycan loss similar to that occurring with cartilage disuse. Unlike degenerative changes, some articular cartilage changes caused by disuse may be reversible. The presence of reversible changes would likely increase the chances of success of head sparing treatment strategies that rely on the viability and mechanical integrity of the articular cartilage.

Adult↗
PubMed2003

Collapse pressures of biodegradable stents.

Biodegradable stent prototypes were produced from poly L-lactic acid polymers with different molecular weights. The effects of molecular weight, drug incorporation and stent design on the collapse pressure of the stents were evaluated. While molecular weights did not show a significant effect on the collapse pressure of the stents, drug incorporation at high percentage decreased the collapse pressure of the stents substantially. Cryogenic fracture surfaces showed significant drug agglomeration as the concentration increased. The design of the stent was also found to a have significant effect on the collapse pressure. The stent produced from the same material has a higher collapse pressure when the load bearing surface area is increased.

Absorbable Implants↗
PubMed1979

Necrotic changes of the adrenal cortex following orthostatic collapse in rabbits.

The adreal gland was studied in 56 adult male rabbits; 44 had been subjected to orthostatic collapse, and 12 served as controls. The animals either died from collapse or were sacrificed at regular intervals up to 30 days after the experimental procedure. Nuclear pyknosis was seen in cortical cells of animals dying in collapse. At 6 or more hours following collapse, necrosis was found involving single cells, or rarely small groups of cells mainly in the zona fasciculata. Regenerative areas were present at 7 and 15 days after collapse. This necrosis may be related to a nutritive disturbance, largely hypoxic in nature (hypovolemia with blood stasis and thrombosis). The adrenal medulla showed only degranulation.

Adrenal Cortex↗
PubMed1996

Type of arrhythmia at EMS arrival on scene in out-of-hospital cardiac arrest in relation to interval from collapse and whether a bystander initiated CPR.

Outcome after cardiac arrest is strongly related to whether the patient has ventricular fibrillation at the time the emergency medical service (EMS) arrives on the scene. The occurrence of various arrhythmias at the time of EMS arrival among patients with out-of-hospital cardiac arrest was studied in relation to the interval from collapse and whether cardiopulmonary resuscitation (CPR) was initiated by a bystander. The patients studied were all those with out-of-hospital cardiac arrest in Goteborg, Sweden, between 1980 and 1992 in whom CPR was attempted by the arriving EMS and for whom the interval between collapse and the arrival of EMS was known. In all, information on the time of collapse and the arrival of EMS was available for 1,737 patients. Among patients for whom EMS arrived within 4 minutes of collapse, 53% were found in ventricular fibrillation/tachycardia. There was a successive decline in occurrence of such arrhythmias with time. However, when the interval exceeded 20 minutes, ventricular fibrillation/tachycardia was still observed in 27% of cases. Bystander CPR increased the occurrence of such arrhythmias regardless of the interval between collapse and EMS arrival.

Adolescent↗
PubMed1993

Refolding of brain-derived neurotrophic factor from guanidine hydrochloride: kinetic trapping in a collapsed form which is incompetent for dimerization.

We have studied the pathway and kinetics of refolding of recombinant human brain-derived neurotrophic factor (BDNF), which is a very tightly-associated dimer in its native state. When BDNF unfolded in 6 M guanidine hydrochloride is diluted 20-fold into phosphate-buffered saline, a partially folded intermediate is rapidly formed (< 1 min). Circular dichroism and fluorescence spectroscopy show that this intermediate has extensive secondary structure, but no well-defined tertiary structure. Size-exclusion chromatography with light scattering detection shows that it is compact and monomeric, and therefore corresponds to what is often called a "collapsed form" or "molten globule". This collapsed form disappears with a half-time of approximately 30 min, simultaneously with the appearance of native dimers, without accumulation of monomeric species with a native tertiary structure. Remarkably, the monomer-dimer association constant of the collapsed form is approximately 10(10) weaker than the native structure, and it has a low tendency to form large aggregates. Given the very large hydrophobic surface present at the dimer interface of nerve growth factor (and presumably in BDNF), these results indicate that these hydrophobic groups are not exposed in the collapsed form, and that it is therefore quite dissimilar from the native structure. A significant conformational change in the collapsed form is necessary to re-expose these hydrophobic groups to form the dimer interface, making this the rate-limiting step in reaching the native conformation.

Brain-Derived Neurotrophic Factor↗