Differential distribution of elastic system fibers in control and bronchoconstricted intraparenchymatous airways in the guinea-pig lung

The elastic system fibers were studied at the light microscopic level by using Weigert's resorcin-fuchsin method after oxidation. This study was designed to describe the distribution of these fibers in intrapulmonary guinea-pig airways and to characterize their conformational changes during bronchoconstriction induced by methacholine aerosol. Airways present a palisade of elastic system fibers just beneath the epithelial basement membrane; these fibers are also present in the adventitial connective tissue. Thin fibers link the fibers located in the palisade among themselves and also connect them to those fibers located in the bronchial adventitial tissue, by traversing the airway smooth muscle. During bronchoconstriction, the fibers located beneath the epithelial basement membrane are divided into two components: one follows the epithelial invaginations towards airway lumen, while the other population remains attached through airway smooth muscle to the fibers located in the adventitial connective tissue. At the ultrastructural level, the findings corroborated those of the light microscopy and in addition, disclosed that typical mature elastic fibers and also elaunin fibers attach directly to the basal lamina, a feature that has not been reported previously in other tissues studied. This configuration is compatible with the idea that fibers of the elastic system restrict the mucosal folding during bronchoconstriction, and may also provide energy to restore airway configuration to its normal status after contraction.

The effect of chemosurgical peels and dermabrasion on dermal elastic tissue

Chemosurgical peel is a technique that has been used widely by plastic surgeons and dermatologists to remove fine and deep wrinkles of the skin. However, the reaction of elastic tissue to the cutaneous application of commonly used chemical peeling agents has not been defined. This study comparatively assessed the alteration in dermal histology and mechanical properties of skin following treatment with 25% and 50% trichloroacetic acid, Baker's phenol solution, and dermabrasion. Yucatan minipigs served as the animal model. The skin was analyzed at five intervals over 6 months after treatment using histologic, quantitative, and mechanical analysis (hematoxylin and eosin, elastic tissue, and Sirius red stains, computerized digital morphometry, and a tensiometer). At 6 months we found no change in the quality, structure, or arrangement of elastic fibers in skin treated with a single application of 25% and 50% trichloroacetic acid or dermabrasion when compared with untreated skin. Skin treated with Baker's phenol solution showed a marked morphologic change in the elastic fibers. The fibers within the regenerated zone of dermis were sparse, wispy, and immature at 6 months after treatment. Preliminary tensiometric analysis of phenol-treated skin at 6 months indicated that the skin was stiffer and weaker. This study questions the possibility of long-term change to the skin by the deep penetration of caustic chemicals to remove wrinkles and rejuvenate the skin.

Penicillamine-induced degenerative dermatoses: report of a case and brief review of such dermatoses

We describe a case of elastosis perforans serpiginosa with additional findings of degenerative skin changes. A 20-year-old man with hepatolenticular degeneration, under prolonged treatment with D-penicillamine, presented with a circular or serpiginous arrangement of nuchal papules. Histopathologically, transepidermal channels were accompanied by granulomatous reactions, with several giant cells engulfing elastic fibers. In addition to these findings of a typical elastosis perforans serpiginosa, we observed scar-like skin changes inside the circular arrangement of the papules. At the scar-like tissue, we found electron-microscopical evidence of randomly aggregated thin collagen fibers with no tendency toward systemic combined bundle formation, which is a characteristic feature of normal collagen fiber formation. Pseudoxanthoma-elasticum-like changes were observed on his neck. On his axillae and groin, slight skin thickening and wrinkling were detected. The diagnosis of elastosis perforans serpiginosa does not represent all of the manifestations or the pathological background described above. The skin manifestations described here represent not only an elastosis but also a total degenerative dermatosis with overhealed collagenosis. Thus, those dermatoses should be summarized as one entity, penicillamine-induced degenerative dermatosis. After considering the pathogenic background and clinical similarities, we further propose to simplify the penicillamine-induced skin manifestations to three categories: acute sensitivity reactions, bullous dermatoses, and degenerative dermatoses.

Localized delivery of heparin to angioplasty sites with iontophoresis

Drug delivery by iontophoresis involves the application of an electric field to move selectively charged drug molecules across biological membranes. The purpose of this study was to assess the efficacy of intravascular iontophoresis in the local delivery of heparin to balloon angioplasty sites by using a recently designed iontophoretic catheter. In vivo heparin iontophoresis was assessed in 33 rats and 21 pigs in four protocols designed to measure the technical determinants of intramural drug deposition, the pharmacokinetics and localization of coronary delivery, and the effect of this technique on platelet deposition following balloon injury. First, iontophoresis of 3H-heparin into the aorta of 33 rats was performed to determine the effects of iontophoretic current, iontophoretic membrane balloon initiation pressure, iontophoresis time, and heparin concentration on intramural drug deposition. Second, iontophoresis of 3H-heparin was performed in 16 porcine coronary arteries to quantitate immediate drug delivery and subsequent wash-out over 24 h. Third, iontophoresis of fluorescent heparin was performed in 8 porcine coronary arteries to define intramural localization of locally delivered drug. Fourth, 111In-labeled platelet deposition was measured 1 h following balloon angioplasty and local iontophoretic heparin delivery in 16 porcine carotid and iliac vessels. Contralateral control vessels that were dilated with the same size balloon and treated with iontophoresis of saline served as controls. Rat aortic studies demonstrated that iontophoresis resulted in 13 times more intramural heparin deposition than passive delivery (passive: 0.3 +/- 0.4 microgram, iontophoresis: 4.6 +/- 1.6 micrograms, P < 0.0004). Iontophoretic membrane balloon inflation pressure had no significant effect on intramural drug deposition, but longer iontophoresis times and higher heparin concentrations resulted in higher levels of intramural heparin (P < 0.05). Porcine coronary studies demonstrated successful intramural deposition of heparin in all arteries without adverse electrical or hemodynamic sequelae, with persistence of the drug for at least 24 h. Localization studies demonstrated immediate deposition of fluorescent heparin in the intima and internal elastic lamina, with subsequent rapid diffusion of the drug into the media. Porcine platelet studies demonstrated that heparin iontophoresis decreased platelet deposition following balloon injury by approximately 66% compared with saline-treated control vessels (heparin-treated: 1.46 +/- 2.51 x 10(8), control: 4.27 +/- 7.02 x 10(8), P = 0.001). This study has demonstrated that local intramural heparin delivery is feasible with an intravascular iontophoretic catheter. Following intracoronary heparin iontophoresis in the porcine model, intramural drug is detected for at least 24 h. Local delivery of heparin with this technique significantly decreases early platelet deposition following balloon injury in peripheral porcine arteries.

Anti-oxidative therapy with oral dapsone improved HCV antibody positive annular elastolytic giant cell granuloma

A 72-year-old fisherman who was positive for the HCV antibody developed an annular, erythematous, infiltrated lesions on sun-exposed areas. The lesions were diagnosed as annular elastolytic giant cell granuloma both clinically and histologically. Topical corticosteroid and cryotherapy with liquid nitrogen for several months failed to improve the lesions. We then started dapsone, a known anti-oxidant, at 50 mg/day. A month later, the margins of the erythematous lesions faded, and the infiltration gradually decreased. No recurrence has been observed for one year after the start of the therapy. Anti-oxidative therapy appears to be effective for annular elastolytic giant cell granuloma and could be an alternate therapy for refractory granulomatous disease.

Further investigation of the use of intratracheally administered hyaluronic acid to ameliorate elastase-induced emphysema

Previously, this laboratory has shown that intratracheally administered hyaluronic acid (HA) significantly reduces air-space enlargement in a hamster model of emphysema induced with pancreatic elastase. Whereas HA was given immediately following elastase in those initial studies, the current investigation determined the effect of instilling HA up to 2 h before or after intratracheal administration of elastase to hamsters. Both 1 and 2 mg HA, given 2 h before pancreatic elastase, significantly decreased (p < .05) air-space enlargement compared to controls (as measured by the mean linear intercept). Instillment of 2 mg HA, 1 h after pancreatic elastase, had a similar effect (p < .05). In contrast, 1 mg HA, given 1 or 2 h after pancreatic elastase, did not significantly affect the mean linear intercept. Against human neutrophil elastase, HA exhibited the same protective effect. While neutrophil elastase induced less air-space enlargement than pancreatic elastase, both 1 and 4 mg of HA, given 2 h prior to the enzyme, still produced a significant reduction (p < .05) in the mean linear intercept. HA exerted this effect despite the fact that it initiates a transient influx of neutrophils into the lung. Since HA does not slow the clearance of intratracheally instilled [14C] albumin from the lung, its mechanism of action may not involve physical interference with the movement of elastase through the lung, but may instead depend on interaction with elastic fibers. Evidence for an association between these two matrix constituents was provided by studies using fluorescein-labeled HA. Overall, these results further suggest that HA may be useful in preventing lung injury by elastases.

Effects of alpha-hydroxy acids on photoaged skin: a pilot clinical, histologic, and ultrastructural study

BACKGROUND

alpha-Hydroxy acids (AHAs) have been reported to improve aging skin. The mechanisms of action of AHAs on epidermal and dermal compartments need clarification.

OBJECTIVE

Our purpose was to determine the effects of AHAs on photoaged human skin by clinical and microanalytic means.

METHODS

Patients applied a lotion containing 25% glycolic, lactic, or citric acid to one forearm and a placebo lotion to the opposite forearm for an average of 6 months. Thickness of forearm skin was measured throughout the study. Biopsy specimens from both forearms were processed for analysis at the end of the study.

RESULTS

Treatment with AHAs caused an approximate 25% increase in skin thickness. The epidermis was thicker and papillary dermal changes included increased thickness, increased acid mucopolysaccharides, improved quality of elastic fibers, and increased density of collagen. No inflammation was evident.

CONCLUSION

Treatment with AHAs produced significant reversal of epidermal and dermal markers of photoaging.

Protection of rat lung from elastase-induced elastic fiber degradation in vitro and from emphysema in vivo by a trifluoroacetylpeptide anilide inhibitor

Trifluoroacetylpeptide anilides are powerful reversible inhibitors of human neutrophil elastase (HNE), a serine protease implicated in the pathogenesis of pulmonary emphysema. The in vitro effectiveness of three inhibitors, CF3CO-Phe-Ala-NH-p-C6H4-CF3 (1), CF3CO-Val-Ala-NH-p-C6H4-CF3 (2) and CF3CO-Lys-Ala-NH-p-C6H4-CH(CH3)2 (3) was analyzed. The protection of lung tissue sections of rats from the degradation induced by HNE has been evaluated quantitatively by automated image analysis. Inhibitor 1 (22 microM), 2 (50 microM) or 3 (35 and 70 microM) significantly reduced the HNE-induced degradation of the elastin network by 75, 42, 54 and 44%, respectively. Inhibitor 3 was tested intratracheally on an experimental model of pulmonary emphysema. Rats that received the elastase inhibitor 1 h before instillation of HNE were significantly protected by 40% from experimental emphysema. Reduced protections were observed with the treatment by the inhibitor 1 or 4 h after challenge with the enzyme.

Basic fibroblast growth factor may repair experimental cerebral aneurysms in rats

BACKGROUND AND PURPOSE

To determine whether basic fibroblast growth factor (FGF) can induce proliferative response of endothelial cells and/or smooth muscle cells in aneurysmal lesions, we investigated the effect of the intravenous administration of basic FGF on experimental cerebral aneurysms.

METHODS

Cerebral aneurysms were induced in rats by ligation of the unilateral common carotid artery, producing hypertension. Three months later, basic FGF was intravenously injected in two groups of randomly divided rats on days 1, 3, and 5 at two different doses (low dose: 2 micrograms/100 g body wt per day; high dose: 5 micrograms/100 g body wt per day). In a control group, normal saline was similarly injected. The junctions of the anterior cerebral artery (ACA) and the olfactory artery (OA) were examined with a light microscope. Aneurysmal changes were defined as the lesions with discontinuity of the internal elastic lamina in more than half of the outward dilated wall. Depending on whether the smooth muscle cell layer was present in the whole wall, the lesions were divided into two stages: early aneurysmal lesion (whole area) and saccular aneurysm (not totally preserved).

RESULTS

The control and the low-dose groups presented no obvious intimal thickening in the intact ACA-OA junctions of both nonligated and ligated sides as well as in the aneurysmal changes. In contrast, in the high-dose group, various degrees of intimal thickening in the wall were detected in 7 of 15 early aneurysmal lesions (P = .019, Fisher's exact test). Immunohistochemistry showed the proliferated cells to be smooth muscle cells.

CONCLUSIONS

These results demonstrate that exogenous basic FGF induces the proliferative response of smooth muscle cells in aneurysmal lesions in rats.

[The effect of steroids on organ-cultured porcine trabecular meshwork--an ultrastructural, biochemical, and lectin histochemical study]

The effect of corticosteroid administration on porcine trabecular meshwork (PTM) was studied by ultrastructural and biochemical analysis. Electron microscopic observations showed an increase of elastic fibers in PTM treated with steroids. Two-dimensional polyacrylamide gel electrophoresis with silver staining showed an increase of proteins with molecular weights of 52 kDa, 66 kDa and 70 kDa. The 66 kDa protein was assumed to be a glycoprotein containing N-acetyl-D-glucosamine, as it was stained positively in the lectin blot analysis with Triticum vulgaris (WGA) and Datura stramonium (DSA). The elastic fibers reacted positively to WGA and DSA, and the degree of this reaction was strengthened by steroid treatment. These results demonstrated that steroid treatment induces ultrastructural and biochemical changes in PTM, and an increase of elastic fibers containing glycoprotein with N-acetyl-D-glucosamine.

In situ mitral valve stabilization with glutaraldehyde

Mitral valve repair in the young rheumatic patient carries a high reoperation rate due to progression of the disease. In an attempt to halt or at least slow down this process, the possibility of fixing in situ the valve tissues with glutaraldehyde was explored. Six weanling sheep underwent tanning of their anterior mitral leaflet for two minutes with 0.5% buffered glutaraldehyde. The non-treated posterior mitral leaflet served as control. The animals were sacrificed at varying intervals between 2.5 and 6 months. At sacrifice, Doppler echocardiography and hemodynamic studies were done. The leaflets were subjected to histopathologic examination and calcium and glutaraldehyde contents were estimated. Glutaraldehyde treatment of the anterior leaflet caused thickening of the cusp and chordae associated with partial devitalization of its core tissue, partial loss of endothelium and intense fibrocellular reaction with abundant elastic fibers without altering its functional integrity. It did not induce calcification. There were no detectable levels of glutaraldehyde at explantation. The posterior mitral leaflets were normal. Although the absence of calcification and partial viability of the tissue are encouraging, it does not necessarily follow that this treatment would arrest progression of the underlying disease. This process may have clinical application in the future, but it is not yet recommended.

Ultrastructural effects of topical tretinoin on dermo-epidermal junction and papillary dermis in photodamaged skin. A controlled study

We examined the effects of daily topical application of 0.05% tretinoin cream on photodamaged Caucasian facial skin by electron microscopy. Specimens obtained pretreatment, after 6 and 12 months of tretinoin therapy (20 patients), and after 6 months of vehicle treatment (5 patients) were compared in a blinded fashion, with special attention to the dermoepidermal junction and papillary dermis. Baseline specimens disclosed various degrees of damage including reduplication of basal lamina, smudging and sparsity of collagen fibers, and nodular arrangement of degenerated microfibrils in the papillary dermis. No significant changes were observed at 6 months in the papillary dermis of either tretinoin-treated or vehicle-treated patients. After 12 months of tretinoin treatment, however, disorganized collagen fibers, which were conspicuous in 11 patients at baseline, were replaced by new well-organized collagen fibers in a wavy pattern in 6 patients. In addition, the amount of nodularly degenerated microfibrillar material decreased in 15 of 18 patients with this finding at baseline. In contrast, no significant change was noted in the number of anchoring fibrils per unit length of the lamina densa. These observations provide further evidence that topical treatment with 0.05% tretinoin produces papillary dermal reconstruction, for which more than 6 months of application were required.

Airway and lung elastic fibre is not reduced in asthma nor in asthmatics following corticosteroid treatment

By morphometric investigation of the relative content of elastic and collagen fibres, we have tested the hypothesis that loss of elastic fibres in the conducting airways and lung parenchyma may reduce tissue elastic recoil, resulting in increased airway maximal closure and apparent increased responsiveness. The study groups comprised: Group A (n = 11) with relatively mild atopic asthma using inhaled bronchodilators prn (i.e. short-term corticosteroids users); Group B (n = 9) with more severe asthma requiring inhaled bronchodilators regularly, and daily inhaled glucocorticosteroids (i.e. longterm corticosteroid users); Group C (n = 12) normal healthy workers. Bronchial biopsy samples were taken from three sites from the left lung. Group A biopsy samples were taken before and after a 4 wk treatment period with inhaled corticosteroids (200 micrograms b.i.d.) and the relative elastic and collagen fibre content of a subepithelial zone was determined from electron micrographs. In a parallel study, the relative proportion of elastic fibre in post mortem lung tissue samples (inner aspect of the bronchial wall, alveolar wall, and points of attachment of surrounding alveoli to intrapulmonary bronchi) from subjects suffering a fatal asthma attack (n = 11), and non-asthmatic suffering sudden death (n = 9), were determined using Miller's elastic and eosin counterstain for light microscopy. In bronchial biopsies of normal subjects, 4.6 (SEM 1.1)% of subepithelial connective tissue was elastic fibre, similar to mild asthmatic subjects, 1.9 (SEM 0.48)%. Neither short-term (4 weeks) inhaled corticosteroid (200 micrograms b.i.d.) nor long-term (< 6 months) treatment with variable doses of inhaled steroids (100-1000 micrograms b.i.d.) significantly altered the elastic or collagen content of the tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative effectiveness of intravascular stents in resisting arterial vasoconstriction: evaluation with use of intact elastic (rabbit aorta) and muscular (dog carotid) arteries in an ex vivo model

PURPOSE

The ability of three different intravascular stents (Gianturco-Roubin, Palmaz-Schatz, and CV Rad), and two different metals (stainless steel and tantalum) to resist vasoconstriction was evaluated in an intact artery ex vivo model.

MATERIALS AND METHODS

Stents were deployed in 21 rabbit thoracic aortae and five dog carotid arteries, which were constricted with phenylephrine and serotonin, respectively. Vasoconstriction was measured with the use of high-frequency ultrasonic imaging.

RESULTS

The maximal vasoconstriction of the control segment was 37.7% +/- 2.6 with rabbit aortae and 36.3% +/- 4.1 with dog carotid arteries, while the average maximal constriction for all segments in which stents were placed was 5.7% +/- 1.1 (P < .01). The maximal constriction of the Gianturco-Roubin stainless steel stent was 9.4% +/- 2.7 versus 7.9% +/- 1.6 with the tantalum version (P = .65). Both designs showed somewhat greater constriction compared with either the Palmaz-Schatz (3.3% +/- 0.9) or the CV Rad (1.4% +/- 1.1) stents.

CONCLUSIONS

Although all of the stents tested substantially resist arterial vasoconstrictive forces, the Palmaz-Schatz and CV Rad stents resist vasoconstriction to a greater degree than the Gianturco-Roubin stents. Tantalum and stainless steel stents of the same design (Gianturco-Roubin) appear similar in their ability to resist vasoconstrictive forces.

Photoirritation: a new photobiologic phenomenon induced by long wavelength UVA radiation in hairless mice treated with broad-spectrum sunscreens

While assessing the protective effect of broad-spectrum sunscreens against chronic UVA radiation, we observed a paradoxical worsening of skin damage with one product. To further examine this finding, five proprietory broad-spectrum sunscreens were applied to albino hairless mice irradiated thrice weekly for 32 weeks with a UVASUN lamp (> 340 nm). Appropriate age-matched controls were included. After approximately 12 weeks, two sunscreens induced a marked dermatitis. Biopsies showed damage greatly exceeding that found in UVA-irradiated, unprotected controls. Histologically, elastic fibers were hyperplastic, coalescing into elastotic clumps. Glycosaminoglycans also increased. Collagen damage was notable since UVA alone does not induce a histologic change. Electron microscopy confirmed these findings. Two other sunscreens provided nearly complete protection. Against chronic UVB radiation, the two UVA photoirritating sunscreens provided substantial protection. Since the UVA sunfilter, oxybenzone, was the same in all sunscreens, we postulate that an irritating component of the vehicle was responsible for the UVA-induced photoirritation. The fifth sunscreen produced severe damage with UVB and UVA.

Changes in extracellular matrix macromolecules in human gingiva after treatment with drugs inducing gingival overgrowth

It is generally agreed that gingival overgrowth results from an increase in the levels of gingival extracellular macromolecules infiltrated with various numbers of inflammatory cells. The relative amounts of extracellular matrix macromolecules observed in 12 cases of gingival hyperplasia associated with the use of cyclosporin, hydantoin or nifedipine were compared with those obtained in a control group on the basis of histological and immunohistochemical investigations. From tissue sections, the quantification was by computerized morphometric analysis on a BFM 186 microcomputer to which were implemented the transformations of mathematical morphology. The area fractions (AA%) occupied by total collagen, type III and type IV collagen, vessels, fibroblasts, fibronectin and elastic fibres were estimated and compared. The overall histological aspects of drug-induced gingival overgrowth were similar, but quantification of different extracellular matrix components showed differences. In the nifedipine and cyclosporin groups, the area occupied by fibroblasts were not significantly greater than in healthy gingiva and chronic gingivitis. The area occupied by collagen was significantly greater in the nifedipine group than in the other pathological groups. Fibronectin was also strongly expressed in the nifedipine group, and the elastic fibre network was preserved in this group.

[Effect of benzquercin on the connective tissue of lathyritic mice. Optic and electron microscopic study]

Vascular pathology is characterized by important alterations of some vessel macromolecular constituents, such as fibrous proteins, collagens and elastin. The purpose of our study was to establish the activity of benzquercin treatment on such alterations of the vascular wall. As experimental model we used lathyrism induced in mice by chronic administration of beta-amino-propionitril (beta-APN). This compound prevents crosslink-formation in elastin and collagen and provokes a disorganization of the structure and an alteration of the physiological functions of the vascular wall. The connective tissue of the skin is also impaired simultaneously with that of the blood vessels. We compared by optical and transmission electron microscopy the morphological structure of the aorta and the skin of 3 groups of mice: a normal control group, an other which only received the beta-APN alone and a third one which received the beta-APN and the benzquercin treatment. The second group, injected with beta-APN without treatment, showed important alterations of the structure of the aorta as well as of the skin. Both fibrous proteins, collagen and elastin were concerned by these alterations, the consequence of which was an increase of the permeability of the aorta wall demonstrated with the horse-radish peroxydase as a tracer. The third group, injected with beta-APN and treated with the benzquercin, showed much less morphological disorders than the untreated group and the vascular permeability was also close to normal controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Immediate ultrastructural effects of endothelin-1 on rabbit basilar artery. A comparison between immersion and perfusion fixation techniques

In this study intra-arterial Endothelin-1 was applied to rabbit basilar arteries and morphological findings were compared between two groups who were either perfusion fixed or immersion fixed. We planned to establish the quantitative dimension of the drug-induced morphological alterations, independent of the fixation technique's effect. There was an abundance of collagenous fibres deposited among the smooth muscle cells which was not observed in control arteries and after immersion fixation. These degenerative changes are similar to the finding following subarachnoid haemorrhage. The only fixation-related difference was the fact that lamina elastica interna was not corrugated in the perfusion fixation group. It is concluded that, the observed changes in the connective tissue of the arterial wall alter the passive elastic properties and so affect the degree of the response to the vasoactive messengers.

Elastic properties and Windkessel function of the human aorta

An understanding of the role of the aortic elastic properties indicates their relevance at several sites of cardiovascular function. Acting as an elastic buffering chamber behind the heart (the Windkessel function), the aorta and some of the proximal large vessels store about 50% of the left ventricular stroke volume during systole. In diastole, the elastic forces of the aortic wall forward this 50% of the volume to the peripheral circulation, thus creating a nearly continuous peripheral blood flow. This systolic-diastolic interplay represents the Windkessel function, which has an influence not only on the peripheral circulation but also on the heart, resulting in a reduction of left ventricular afterload and improvement in coronary blood flow and left ventricular relaxation. The elastic resistance (or stiffness), which the aorta sets against its systolic distention, increases with aging, with an increase in blood pressure, and with pathological changes such as atherosclerosis. This increased stiffness leads to an increase in systolic blood pressure and a decrease in diastolic blood pressure at any given mean pressure, an increase in systolic blood velocity, an increase in left ventricular afterload, and a decrease in subendocardial blood supply during diastole, and must be considered a major pathophysiological factor, for example, in systolic hypertension. The elastic properties of the aortic Windkessel can be assessed in vivo in humans in several ways, most easily by measuring the pulse wave velocity along the aorta. The higher this velocity, the higher the elastic resistance, that is, the stiffness. Other methods depend on assessment of the ratio between pulse pressure and aortic volume changes (delata P/delta V), which can be assessed noninvasively by ultrasonic or tomographic methods. All assessments of vessel stiffness have to take into account the direct effect of current blood pressure, and thus judgements about influences of interventions rely on an unchanged blood pressure. Alternatively, to derive the "intrinsic" stiffness of the aortic wall one has to correct for the effect of the blood pressure present. Recently reports about pharmacologic influences on the elastic properties of the aorta have emerged in the literature.(ABSTRACT TRUNCATED AT 400 WORDS)

Biomechanical properties of normal tendons, normal palmar aponeuroses and palmar aponeuroses from patients with Dupuytren's disease subjected to elastase and chondroitinase treatment

Normal tendons, normal palmar aponeuroses and specimens from patients with Dupuytren's disease, namely apparently normal palmar aponeuroses and contracture bands were subjected to elastase and chondroitinase ABC digestion. Maximum Young's modulus, normalized hysteresis loop and residual elongation were determined before and after enzyme treatment. In normal tendons, normal and apparently normal palmar aponeuroses both normalized hysteresis loop and residual elongation increased significantly after elastase treatment, whereas the stiffness decreased. Normalized hysteresis loop and residual elongation display changes corresponding to the amount of digested elastin. The increased viscosity of untreated contracture bands containing less elastin, as compared to normal palmar aponeurosis, was not affected by elastase. Obviously, the elastic fibers in normal shape and distribution are responsible for maintaining an elastic status with a low viscous stress component. With the exception of contracture bands chondroitinase ABC caused a minor increase of residual elongation and as opposed to elastase a decrease of normalized hysteresis loop indicating an increased mobility of the tissue fibers.

Effect of neuromuscular blockade on the elastic properties of the lungs, thorax, and total respiratory system in anesthetized pigs

OBJECTIVE

To evaluate the effect of neuromuscular blockade on the elastic properties of the lungs, thorax, and total respiratory system in pigs anesthetized to suppress spontaneous breathing.

DESIGN

Prospective, randomized, experimental study.

SETTING

A research laboratory at a university medical center.

SUBJECTS

Eight healthy, anesthetized pigs, weighing 22 to 25 kg.

INTERVENTIONS

Pigs, with and without muscular blockade, were mechanically ventilated during an infusion of sodium pentobarbital that was titrated to suppress spontaneous breathing activity.

MEASUREMENTS AND MAIN RESULTS

No significant differences were observed between pressure/volume curves of the lungs, the chest wall, and the total respiratory system, as determined by inflating and deflating the lungs during anesthesia, with or without neuromuscular blockade, in random order. Functional residual capacity was 985 +/- 87 mL with neuromuscular blockade and 997 +/- 78 mL without neuromuscular blockade (NS). A comparison of the total respiratory system, lung, and chest wall compliances obtained with and without neuromuscular blockade showed high correlations (total respiratory system compliance [r2 = .86]; chest wall compliance [r2 = .83]).

CONCLUSION

Neuromuscular blockade does not alter the elastic properties of the lungs, chest wall, or total respiratory system in mechanically ventilated pigs receiving sodium pentobarbital anesthesia to suppress spontaneous breathing efforts.

The Fibrel mechanism of action study. A preliminary report

BACKGROUND

Fibrel is a medical implant device that has demonstrated use in the correction of cutaneous depressions from acne scars and wrinkles.

OBJECTIVE

Mechanisms of actions have been proposed that have theorized the production of new collagen over time as a result of the Fibrel implant. The present study utilized human volunteers to study the histologic response of Fibrel over time.

METHODS

Fibrel was injected into tattoo sites behind the ears of human volunteers; skin biopsies were taken at various time intervals and studied histologically by a clinical pathologist.

RESULTS

An overall increase over time was noted with regard to production of collagen and inflammatory response. No change in elastic tissue was found.

CONCLUSIONS

Fibrel does promote new collagen synthesis and inflammatory response and thus is useful to correct cutaneous depressions via soft tissue augmentation.

D-penicillamine-induced elastosis perforans serpiginosa and localized cutis laxa in a patient with Wilson's disease

A patient with Wilson's disease who developed elastosis perforans serpiginosa and localized cutis laxa during prolonged treatment with D-penicillamine is described. Induction of elastosis perforans serpiginosa and of cutis laxa by D-penicillamine may be due to a similar mechanism.

Low-dose tretinoin does not improve striae distensae: a double-blind, placebo-controlled study

Striae distensae occur on the abdomen and/or breast in 90 percent of all pregnant women and are the result of extrinsic and intrinsic factors. This study investigated the response of pregnancy-related abdominal striae to treatment with tretinoin cream (0.025 percent) applied daily for seven months. In this study, eleven subjects were randomly assigned to tretinoin or placebo treatment groups. Before and after photographs were evaluated by a standardized system. There was no difference or improvement in the treated group compared with control subjects. Tretinoin 0.025 percent cream was ineffective in improving striae distensae in these subjects.