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ARTICLE INFO Keywords: Loganin Connective tissue growth factor Diabetic nephropathy ABSTRACT Connective tissue growth factor (CTGF) plays a pathogenic role in diabetic nephropathy (DN). Loganin, an iridoid glucoside compound was [...]

Stiffness changes in response to mechanical and chemical stimulation were studied in muscle-free dermal samples from the body wall of the starfish Linckia laevigata. The ultrastructural study showed that the dermis was packed with collagen fibrils between which only a small number of cells were observed. Muscles were found only in the walls of coelomic extensions leading to papulae. Stress-strain tests were performed on isolated dermis containing no muscles. The tangent modulus was 27.5 MPa at 0.04% strain rate in the stress-strain tests. It was increased to 40.7 MPa by mechanical stimulation, which also increased the tensile strength and breaking-strain energy density. Dynamic mechanical tests showed that the increase in stiffness in response to mechanical stimulation was transient. Acetylcholine ([10.sup.-6] - [10.sup.-3] mol [l.sup.-1) and artificial seawater with an elevated potassium concentration (KASW) stiffened the dermis. Mechanical stimulation caused a 12% mass loss. KASW also caused mass loss, which was inhibited by anesthesia. These results clearly showed that the stiffness changes in the starfish dermis were based on a non-muscular mechanism that was similar to that of other echinoderm connective tissues with mechanical mutability., Introduction Starfish change their body stiffness. On one hand they stiffen the body when it is mechanically stimulated (Motokawa and Wainwright, 1991), which is very probably a defensive behavior. On [...]

A lipid core that occupies a high proportion of the plaque volume in addition to a thin fibrous cap is a predominant indicator of plaque vulnerabiliy. Nowadays, noninvasive imaging modalities can identify such structural components, however, morphological criteria alone cannot reliably identify high-risk plaques. Information, such as stresses in the lesion's components, seems to be essential. This work presents a methodology able to analyze the effect of changes in the lipid core and calcification on the wall stresses, in particular, on the fibrous cap vulnerability. Using high-resolution magnetic resonance imaging and histology of an ex vivo human atherosclerotic carotid bifurcation, a patient-specific three-dimensional geometric model consisting of four tissue components, is generated. The adopted constitutive model accounts for the nonlinear and anisotropic tissue behavior incorporating the collagen fiber orientation by means of a novel and robust algorithm. The material parameters are identified from experimental data. A novel stress-based computational cap vulnerability index is proposed to assess quantitatively the rupture-risk of fibrous caps. Nonlinear finite element analyses identify that the highest stress regions are located at the vicinity of the shoulders of the fibrous cap and in the stiff calcified tissue. A parametric analysis reveals a positive correlation between the increase in lipid core portion and the mechanical stress in the fibrous cap and, hence, the risk for cap rupture. The highest values of the vulnerability index, which correlate to more vulnerable caps, are obtained for morphologies for which the lipid cores were severe; heavily loaded fibrous caps were thus detected. The proposed multidisciplinary methodology is able to investigate quantitatively the mechanical behavior of atherosclerotic plaques in patient-specific stenoses. The introduced vulnerability index may serve as a more quantitative tool for diagnosis, treatment and prevention. [DOI: 10.1115/1.4000078] Keywords: artery, calcification, carotid bifurcation, fibrous cap, lipid core, MRI, vulnerability

The purpose of this study was to investigate whole muscle and single muscle fiber adaptations in very old men in response to progressive resistance training (PRT). Six healthy independently living old men (82 [+ r -] 1 yr; range 80-86 yr, 74 [+ or -] 4 kg) resistance-trained the knee extensors (3 sets, 10 repetitions) at ~70% one repetition maximum 3 days/wk for 12 wk. Whole thigh muscle cross-sectional area (CSA) was assessed before and after PRT using computed tomography (CT). Muscle biopsies were obtained from the vastus lateralis before and after the PRT program. Isolated myosin heavy chain (MHC) I and Ha single muscle fibers (n = 267; 142 pre; 125 post) were studied for diameter, peak tension, shortening velocity, and power. An additional set of isolated single muscle fibers (n = 2,215; 1,202 pre; 1,013 post) was used to identify MHC distribution. One repetition maximum knee extensor strength increased (P < 0.05) 23 [+ or -] 4 kg (56 [+ or -] 4 to 79 [+ or -] 7 kg; 41%). Muscle CSA increased (P < 0.05) 3 [+ or -] 1 [cm.sup.2] (120 [+ or -] 7 to 123 [+ or -] 7 [cm.sup.2]; 2.5%). Single muscle fiber contractile function and MHC distribution were unaltered with PRT. These data indicate limited muscle plasticity at the single-muscle fiber level with a resistance-training program among the very old. The minor increases in whole muscle CSA coupled with the static nature of the myocellular profile indicate that the strength gains were primarily neurological. These data contrast typical muscle responses to resistance training in young (~20 yr) and old (~70 yr) humans and indicate that the physiological regulation of muscle remodeling is adversely modified in the oldest old. sarcopenia; aging; contractile function

Tendons and ligaments are unique forms of connective tissue that are considered an integral part of the musculoskeletal system. The ultimate function of tendon is to connect muscles to bones and to conduct the forces generated by muscle contraction into movements of the joints, whereas ligaments connect bone to bone and provide joint stabilization. Unfortunately, the almost acellular and collagen I--rich structure of tendons and ligaments makes them very poorly regenerating tissues. Injured tendons and ligaments are considered a major clinical challenge in orthopedic and sports medicine. This Review discusses the several factors that might serve as molecular targets that upon activation can enhance or lead to tendon neoformation., Introduction Tendons and ligaments are bundles of parallel fibers made of dense connective tissue that play an important role in mediating normal movement and stability of joints, respectively (1), (2) [...]

We examined the effects of 35 and 90 days of simulated microgravity with or without resistance-exercise (RE) countermeasures on the content of the general skeletal muscle protein fractions (mixed, sarcoplasmic, and myofibrillar) and specific proteins that are critical for muscle function (myosin, actin, and collagen). Subjects from two studies, using either unilateral lower limb suspension (ULLS) or bed rest (BR), comprised four separate groups: 35 days ULLS (n = 11), 35 days ULLS+RE (n = 10), 90 days BR (n = 9), and 90 days BR+RE (n = 8). RE consisted of four sets of seven maximal concentric and eccentric repetitions of the quadriceps femoris muscles that were performed 2 or 3 times per week. Pre- and post-simulated weightlessness muscle biopsies were analyzed from the vastus lateralis of all groups and the soleus of the 35-day ULLS and 90-day BR groups. The general protein fractions and the specific proteins myosin, actin, and collagen of the vastus lateralis were unchanged (P > 0.05) in both control and countermeasures groups over 35 and 90 days, despite large changes in quadriceps femoris muscle volume (35 days ULLS: -9%, 35 days ULLS+RE: +8%; and 90 days BR: -18%, 90 days BR+RE: -1%). The soleus demonstrated a decrease in mixed (35 days ULLS: -12%, P = 0.0001:90 days BR: -12%, P = 0,004) and myofibrillar (35 days ULLS: -12%, P = 0.009:90 days BR: -8%, P = 0.04) protein, along with large changes in triceps surae muscle volume (35 days ULLS: -11%; 90 days BR: -29%). Despite the loss of quadriceps femoris muscle volume or preservation with RE countermeasures during simulated microgravity, the quadriceps femoris muscles are able to maintain the concentrations of the general protein pools and the main contractile and connective tissue elements. Soleus muscle protein composition appears to be disproportionately altered during long-duration simulated weightlessness. bed rest: spaceflight; resistance exercise: myosin; actin: collagen

Puberty unmasks or accelerates progressive kidney diseases, including diabetes mellitus (DM), perhaps through effects of sex steroids. To test the hypothesis that rising androgen levels at puberty permit diabetic kidney damage, we studied four groups of male rats with and without streptozocin-induced DM: adult onset (A), adult onset after castration (AC), juvenile onset (J), and juvenile onset with testosterone treatment (JT). Profibrotic markers were measured after 6 wk with blood glucose levels 300-450 mg/dl. JT permitted increased expression of mRNA for two isoforms of transforming growth factor-[beta] and connective tissue growth factor compared with J animals with DM; prior castration did not provide protection in adult-onset DM. JT also permitted greater tubular staining for or-smooth muscle actin and fibroblast-specific protein, two markers of cell damage and potential epithelial mesenchymal transition. Once again, castration was not protective for these effects of DM in the AC group. These data indicate that puberty permits detrimental effects in the tubulointerstitium in the diabetic kidney, an effect mimicked by testosterone treatment of juvenile animals and partially blunted by castration of adults, hut damage does not correlate with testosterone levels, suggesting a less direct mechanism. connective tissue growth factor; transforming growth factor-[beta]; epithelial mesenchymal transition; glomerulus; castration doi:10.1152/ajprenal.00482.2006.

The cardiac extracellular matrix (ECM) maintains the structural and mechanical integrity of the myocardium. We determined the alterations in the composition of the ECM coincident with the transition from compensated left ventricular (LV) hypertrophy (LVH) to symptomatic congestive heart failure (CHF) and the mechanisms underlying such changes. Heart failure was induced in ferrets by aortic banding. Myocardial collagen content was assessed by HPLC and histological analysis. Matrix metalloproteinase (MMP) activity and tissue inhibitor of metalloproteinase (TIMP) expression were evaluated using gelatin zymography and Western blotting, respectively. LV free wall thickness increased by 29% in asymptomatic LVH and was associated with a 20% increase in interstitial fibrosis (P < 0.05). CHF was coincident with increased plasma angiotensin II levels (149 [+ or -] 48, 40 [+ or -] 19, and 5.6 [+ or -] 1 pg/ml for CHF, LVH, and sham, respectively: P < 0.01, CHF vs. sham and LVH), ventricular dilatation (LV internal diameter = 15 [+ or -] 0.4 vs. 9 [+ or -] 0.1 mm, P < 0.05), increased active MMP-9 (3.0-and 2.2-fold increase over sham and LVH, respectively, n = 5-10 animals per group, P < 0.01), and reduced myocardial total collagen content (3.5 [+ or -] 0.4, 2.6 [+ or -] 0.3, and 2.2 [+ or -] 0.3% in sham, LVH, and CHF, respectively, P < 0.05). In CHF the distribution of collagen was markedly altered, becoming punctate in nature. No difference in MMP-2 activity, TIMP-1, TIMP-2, TIMP-3, or TIMP-4 expression, or collagen cross-linking was found at any time. The present work demonstrates structural reorganization and loss of collagen from cardiac ECM during the transition to decompensated CHF. The enhanced MMP-9 activity coincident with the transition to CHF provides potential therapeutic opportunities for managing the progression from asymptomatic LVH to symptomatic CHF. connective tissue; extracellular matrix; matrix metalloproteinase

Denervation or inactivity is known to decrease the mass and alter the phenotype of muscle and the mechanics of tendon. It has been proposed that a shift in the collagen of the extracellular matrix (ECM) of the muscle, increasing type III and decreasing type I collagen, may be partially responsible for the observed changes. We directly investigated this hypothesis using quantitative real-time PCR on muscles and tendons that had been denervated for 5 wk. Five weeks of denervation resulted in a 2.91-fold increase in collagen concentration but no change in the content of collagen in the muscle, whereas in the tendon there was no change in either the concentration or content of collagen. The expression of collagen I, collagen III, and lysyl oxidase mRNA in the ECM of muscle decreased (76 [+ or -] 1.6%, 73 [+ or -] 2.3%, and 83 [+ or -] 3.2%, respectively) after 5 wk of denervation. Staining with picrosirius red confirmed the earlier observation of a change in staining color from red to green. Taken with the observed equivalent decreases in collagen I and III mRNA, this suggests that there was a change in orientation of the ECM of muscle becoming more aligned with the axis of the muscle fibers and no change in collagen type. The change in collagen orientation may serve to protect the smaller muscle fibers from damage by increasing the stiffness of the ECM and may partly explain why the region of the tendon closest to the muscle becomes stiffer after inactivity. connective tissue; inactivity; injury; picrosirius red; exercise

Advanced glycation end products (AGEs) are elevated in aged and diabetic individuals and are associated with pathological changes associated with both. Previously we demonstrated that the AGE [N.sup.[epsilon]]-(carboxymethyl)lysine (CML)-collagen induced fibroblast apoptosis through the cytoplasmic and mitochondrial pathways and the global induction of proapoptotic genes. In the present study we investigated upstream mechanisms of CML-collagen-induced apoptosis. CML-collagen induced activation of the proapoptotic transcription factor FOXO1 compared with unmodified collagen. When FOXO1 was silenced, CML-collagen-stimulated apoptosis was reduced by ~75% compared with fibroblasts incubated with nonsilencing small interfering RNA, demonstrating the functional significance of FOXO1 activation (P < 0.05). CML-collagen but not control collagen also induced a 3.3-fold increase in p38 and a 5.6-fold increase in JNK(1/2) activity (P < 0.05). With the use of specific inhibitors, activation of p38 and JNK was shown to play an important role in CML-collagen-induced activation of FOXO1 and caspase-3. Moreover, inhibition of p38 and JNK reduced CML-collagen-stimulated apoptosis by 48 and 57%, respectively, and by 89% when used together (P < 0.05). In contrast, inhibition of the phosphatidylinositol 3-kinase/Akt pathway enhanced FOXO1 activation, p38 and JNK stimulation by CML-collagen was almost entirely blocked when formation of ROS was inhibited and was partially reduced by NO and ceramide inhibitors. These inhibitors also reduced apoptosis to a similar extent. Together these data support a model in which AGE-induced apoptosis involves the formation of ROS, NO, and ceramide and leads to p38 and JNK MAP kinase activation, which in turn induces FOXO1 and caspase-3. diabetes; connective tissue; mitogen-activated protein kinase; reactive oxygen species

Connexin-36 (Cx36) is the only gap junction protein that has been unambiguously identified in rodent pancreatic [beta]-cells. However, properties of gap junction channel unitary currents between [beta]-cells remain unrevealed. To address whether Cx36 forms functional channels in [beta]-cells, we characterized biophysical properties of macro- and microscopic junctional currents recorded from dual whole cell voltage clamp isolated pairs of dispersed mouse [beta]-cells. Electrical coupling was recorded in 80% of cell pairs with a junctional conductance ([g.sub.j]) of 355 [+ or -] 45 pS (n = 20). Transjunctional voltage dependence was identified in three of seven cell pairs with high-input membrane resistances. Normalized steady-state [g.sub.j] ([G.sub.j]) and transjunctional-voltage relation were well described by a two-state Boltzmann equation [maximal conductance ([G.sub.max]) = 1.0. voltage-insensitive conductance ([G.sub.min]) = 0.3 and 0.28, voltage gating sensitivity (A) = 0.21 and 0.23, and voltage at which one-half of the initial voltage-dependent conductance was reached ([V.sub.o]) = -85 and 87 mV for negative and positive potentials, respectively]. Halothane reversibly uncoupled [beta]-cell pairs, and, during recovery, unitary conductances of 5-10 pS were recorded while using patch pipettes containing mainly CsCl. Although these properties are similar to those previously described for Cx36 channels in mammalian cell systems, we found that [beta]-cell junctional currents were insensitive to quinine. Cx36 transcript and protein expression in islets and freshly dispersed cell preparations was confirmed by RT-PCR and immunolluorescence. In conclusion, biophysical properties of junctional channels between [beta]-cells are similar but not identical to those previously described for homomeric Cx36 channels. Cell type-specific mechanisms that may account for these differences are discussed. islets of Langerhans; insulin; connexin; intercellular communication

The objective of this studywas to evaluate attributes in semitendinosus muscle (ST) associated with tenderness in divergent breeds--Wagyu (W; n = 12), Limousin (L; n = 12), and Wagyu x Limousin cross cattle (WxL; n = 12)--fed two dietary treatments (0 or 6% sunflower oil, DM basis). A randomized complete block repeated measures design with a 3 x 2 factorial arrangement of treatments was used to measure effects of breed, diet, block, and associated interactions. Cattle were fed barley-based diets for an average of 259 d. Temperature and pH were measured at 0, 1, 3, 6, 12, and 24 h postmortem (PM). Steaks from the ST were removed 24 h postmortem, vacuum-packaged, aged (1, 3, 7, 14, 28, and 56 d postmortem) at 2[degrees]C, and frozen (-40[degrees]C) until analyzed. Dietary treatment did not (P > 0.10) affect Warner-Bratzler shear force (WBSF), collagen amount (OH-PRO) or cross-linking (HP), temperature, or pH. Steaks from WxL aged 14 d postmortem had lower (P < 0.05) WBSF values than L (W were intermediate). Cooking time was longer (P < 0.01) in W and WxL than in L; however, breed did not affect (P > 0.10) cooking loss. Cooking time was not influenced by diet, but steaks from cattle fed 6% sunflower oil had lower (P < 0.05) cooking losses. Temperature decreased more (P < 0.05) rapidly, and pH more slowly (P < 0.05), in W and WxL than L in the first 24 h postmortem. Limousin steaks were lighter (higher L*) and more yellow (higher b *) in color than steaks from W and WxL (P < 0.05). The control diet (no oil added) resulted in steaks that were lighter (P < 0.05) than the treatment diet (6% added sunflower oil). Neither breed nor diet affected (P > 0.10) OH-PRO or HP concentration. The results of this study indicate that biological type differences may not be as great in the ST as in longissimus muscle; thus, to increase tenderness in ST, emphasis may need to be placed on processing and cooking techniques rather than genetic selection. Key Words: Beef, Connective Tissue, Limousin, Semitendinosus, Tenderness, Wagyu

The uptake and lysosomal degradation of collagen by fibroblasts constitute a major pathway in the turnover of connective tissue. However, the molecular mechanisms governing this pathway are poorly understood. Here, we show that the urokinase plasminogen activator receptor-associated protein (uPARAP)/Endo180, a novel mesenchymally expressed member of the macrophage mannose receptor family of endocytic receptors, is a key player in this process. Fibroblasts from mice with a targeted deletion in the uPARAP/Endo180 gene displayed a near to complete abrogation of collagen endocytosis. Furthermore, these cells had diminished initial adhesion to a range of different collagens, as well as impaired migration on fibrillar collagen. These studies identify a central function of uPARAP/ Endo180 in cellular collagen interactions.

Injury to soft tissue results in the lowering of interstitial fluid pressure ([P.sub.if]), plasma protein extravasation, and increased total tissue volume. In this study, the effects of N-acetyl neurotensin(8-13) [AcNT(8-13)] on [P.sub.if] in rat trachea were examined after electrical stimulation (ES) of the vagus nerve. [P.sub.if] was measured with glass capillaries connected to a servo-controlled counterpressure system. In pentobarbital-anesthetized female Wistar rats, the [P.sub.if] after intravenous saline was -1.8 [+ or -] 0.3 mmHg (means [+ or -] SD) and decreased to -5.0 [+ or -] 0.6 mmHg (P < 0.01, n = 9) after ES. AcNT(8-13) (10 [micro]g/kg) blocked the fall in [P.sub.if] after ES (-2.5 [+ or -] 2.3 mmHg, P < 0.01, n = 8). In tracheal tissue from animals pretreated with AcNT(8-13) at the same dose and immersed in phosphate-buffered saline (0.15 M, pH 7.4), the rate of fluid accumulation in excised tissues was significantly reduced after 2 h. The ability of AcNT(8-13) to modulate the fluid mechanics of tracheal interstitium after inflammation suggests that it may be a useful tool for studying cell adhesion and related factors that maintain structural integrity of connective tissue after injury. peptide; anti-inflammatory effect; micropuncture; neurogenic inflammation

Matrix metalloproteinases (MMPs) are a family of multidomain enzymes involved in the physiological degradation of connective tissue, as well as in pathological states such as tumor invasion and arthritis. Apart from transcriptional regulation, MMPs are controlled by proenzyme activation and a class of specific tissue inhibitors of metalloproteinases (TIMPs) that bind to the catalytic site. TIMP-2 is a potent inhibitor of MMPs, but it has also been implicated in a unique cell surface activation mechanism of latent MMP-2/gelatinase A/type IV collagenase (proMMP-2), through its binding to the hemopexin domain of proMMP-2 on the one hand and to a membrane-type MMP activator on the other. The present crystal structure of the human proMMP-2/TIMP-2 complex reveals an interaction between the hemopexin domain of proMMP-2 and the C-terminal domain of TIMP-2, leaving the catalytic site of MMP-2 and the inhibitory site of TIMP-2 distant and spatially isolated. The interfacial contact of these two proteins is characterized by two distinct binding regions composed of alternating hydrophobic and hydrophilic interactions. This unique structure provides information for how specificity for noninhibitory MMP/ TIMP complex formation is achieved.

Cytochalasin D induces edema formation and lowering of interstitial fluid pressure in rat dermis. Am J Physiol Heart Circ Physiol 281: H7-H13, 2001.--The increased capillary fluid filtration required to create a rapid edema formation in acute inflammation can be generated by lowering the interstitial fluid pressure ([P.sub.IF]). The lowering of [P.sub.IF] appears to involve dynamic [[Beta].sub.1]-integrin-mediated interactions between dermal cells and extracellular matrix fibers. The present study specifically investigates the role of the cell cytoskeleton, i.e., the contractile apparatus of cells, in controlling [P.sub.IF] in rat skin as the integrins are linked to both the cytoskeleton and the extracellular matrix. [P.sub.IF] was measured using a micropuncture technique in the dorsal skin of the hind paw at a depth of 0.2-0.5 mm and following the induction of circulatory arrest with the intravenous injection of KCl in pentobarbital anesthesia. This procedure prevented the transcapillary flux of fluid and protein leading to edema formation in acute inflammation, which in turn can increase the [P.sub.IF] and therefore potentially mask a decrease of [P.sub.IF]. Control [P.sub.IF] (n = 42) averaged -0.8 [+ or -] 0.5 (means [+ or -] SD) mmHg. In the first group of experiments, subdermal injection of 2 [micro]l cytochalasin D, a microfilament-disrupting drug, lowered [P.sub.IF] to an average of -2.8 [+ or -] 0.7 mmHg within 40 min postinjection (P [is less than] 0.05 compared with control). Subdermal injection of vehicle (10% DMSO in PBS or PBS alone) did not change the [P.sub.IF] (P [is greater than] 0.05). Lowering of the [P.sub.IF] was not observed after the injection of colchicine or nocodazole, which specifically disrupts microtubuli in cultured cells. In the second group of experiments, 2 [micro]l of cytochalasin D injected subdermally into rats with intact circulation increased the total tissue water (TTW) and albumin extravasation rate ([E.sub.ALB]) by 0.7 [+ or -] 0.2 and 0.4 [+ or -] 0.3 ml/g dry wt, respectively (P [is less than] 0.05 compared with vehicle). Nocodazole and colchicine did not significantly alter the TTW or [E.sub.ALB] compared with the vehicle (P [is greater than] 0.05). Taken together, these findings strongly suggest that the connective tissue cells can participate in control of [P.sub.IF] via the actin filament system. In addition, the observation that subdermal injection of cytochalasin D lowered [P.sub.IF] indicates that a dynamic assembly and disassembly of actin filaments also occurs in the cells of dermal tissues in vivo. acute inflammation; loose connective tissue; tissue fluid volume

Effects of fibrogenic mediators on the development of pancreatic fibrosis in a TGF-[Beta]1 transgenic mouse model. Am J Physiol Gastrointest Liver Physiol 280: G164-G172, 2001.--The pancreas morphology of transgenic mice that overexpress transforming growth factor-[Beta]1 (TGF-[Beta]1) in the pancreas resembles partially morphological features of chronic pancreatitis, such as progressive accumulation of extracellular matrix (ECM). Using this transgenic mouse model, we characterized the composition of pancreatic fibrosis and involved fibrogenic mediators. On day 14 after birth, fibrotic tissue was mainly composed of collagen type I and III. At this time, mRNA levels of TGF-[Beta]1 were increased. On day 70, the ECM composition was expanded by increased deposition of fibronectin, whereas connective tissue growth factor, fibroblast growth factor (FGF)-1, and FGF-2 mRNA expression levels were elevated in addition to TGF-[Beta]1. In parallel, the number of pancreatic stellate cells (PSC) increased over time. In vitro, TGF-[Beta]1 stimulated collagen type I expression but not fibronectin expression in PSC, in contrast to FGF-2, which stimulated both. This confirms that TGF-[Beta]1 mediates pancreatic fibrosis through activation of PSC and deposition of collagen type I and III at early time points. Furthermore, this points to an indirect mechanism in which TGF-[Beta] regulates pancreatic ECM assembly by induction of additional growth factors. transforming growth factor-B; connective tissue growth factor; fibroblast growth factor-2; chronic pancreatitis; pancreatic stellate cells

The role of neutrophils and alpha 1-antitrypsin on coal- and silica-induced breakdown of connective tissues was investigated. Silica or coal was instilled into normal rats or rats pretreated with antiserum against neutrophils for this purpose. Experimental results showed that connective tissue breakdown is initially caused largely by neutrophil-derived proteases and that significantly increased levels of functional alpha 1-antitrypsin do not prevent this breakdown.