Biomedical subjects

B Starcher

Publications and source records attributed to B Starcher.

At least 19 recordsLinked to original sources

PubMed2005

Dermal connective tissue development in mice: an essential role for tenascin-X.

Deficiency of the extracellular matrix protein tenascin-X (TNX) causes a recessive form of Ehlers-Danlos syndrome (EDS) characterized by hyperextensible skin and hypermobile joints. It is not known whether the observed alterations of dermal collagen fibrils and elastic fibers in these patients are caused by disturbed assembly and deposition or by altered stability and turnover. We used biophysical measurements and immunofluorescence to study connective tissue properties in TNX knockout and wild-type mice. We found that TNX knockout mice, even at a young age, have greatly disturbed biomechanical properties of the skin. No joint abnormalities were noted at any age. The spatio-temporal expression of TNX during normal mouse skin development, during embryonic days 13-19 (E13-E19), was distinct from tropoelastin and the dermal fibrillar collagens type I, III, and V. Our data show that TNX is not involved in the earliest phase (E10-E14) of the deposition of collagen fibrils and elastic fibers during fetal development. From E15 to E19, TNX starts partially to colocalize with the dermal collagens and elastin, and in adult mice, TNX is present in the entire dermis. In adult TNX knockout mice, we observed an apparent increase of elastin. We conclude that TNX knockout mice only partially recapitulate the phenotype of TNX-deficient EDS patients, and that TNX could potentially be involved in maturation and/or maintenance of the dermal collagen and elastin network.

Animals↗

PubMed2001

A ninhydrin-based assay to quantitate the total protein content of tissue samples.

Quantitation of small tissue samples for total protein content is essential for many biochemical analyses. In this study a ninhydrin method for measuring the total protein content of tissue hydrolysates is presented. The ninhydrin reagent is stable at room temperature for up to 1 month in the ethylene glycol-sodium acetate solvent system without the requirement for a nitrogen atmosphere. The reaction was very accurate and precise, with intra- and interassay variations of less than 3% when 5 microg of protein was assayed. All proteins that were investigated contributed the same color intensity per microgram protein as bovine serum albumin. This assay was several times more sensitive than the Coomassie reaction and linear over a greater range of protein concentration.

Ninhydrin↗

PubMed2000

Role for tumour necrosis factor-alpha receptors in ultraviolet-induced skin tumours.

The biological effects of tumour necrosis factor (TNF)-alpha are mediated through either the TNFR1 or the TNFR2 receptor. In the present study, the effects of ultraviolet (UV) irradiation on skin pathology and tumour promotion were studied in hairless mice deficient in either the TNFR1 or the TNFR2 receptor. SKH-1 hairless mice were crossed with either TNFR1 knockout (KO) mice or TNFR2 KO mice to develop a strain of hairless mice deficient in either of these receptors. Elastosis and other pathological indications of UVB irradiation were not affected by the loss of either receptor. The absence of either receptor, however, resulted in a highly significant reduction in skin tumours in response to UVB irradiation. Inflammatory cell influx following chronic UV irradiation was virtually eliminated in the TNFR1 KO mice, while the TNFR2 KO mice responded to UV irradiation with the normal increase in inflammatory cells throughout the lower and upper dermis. Contact hypersensitivity responses were eliminated in the TNFR2 KO mice, whereas the TNFR1 KO mice retained normal contact hypersensitivity reactions. These studies suggest that TNF-alpha plays no part in the accumulation of excessive elastin in the skin during chronic UVB exposure. However, there appears to be an important role for TNF-alpha in mediating tumorigenesis, distinct from its role in initiating cutaneous immune responses.

Animals↗

PubMed1999

UVB irradiation stimulates deposition of new elastic fibers by modified epithelial cells surrounding the hair follicles and sebaceous glands in mice.

UVB irradiation stimulates the synthesis of elastin in the skin of humans and experimental animals. In this study we localized the site and the cells that are responsible for the synthesis of murine dermal elastic fibers. SKH-1 hairless mice were irradiated with UVB and the skin removed for light microscopy, electron microscopy, in situ hybridization, immunohistochemistry, and biochemical studies. In response to chronic low doses of UVB there was an initial moderate increase in tropoelastin mRNA in the papillary dermis. By contrast, there was a continuous marked elevation of collagen alpha1(I) message localizing to sites of inflammatory cell influx throughout the upper and lower dermis. After 25 wk of UV irradiation there was a 2-fold increase in skin elastin, yet total collagen remained unchanged. Serial desmosine analysis from en face sections indicated the increase in elastin content was due to dermal elastic fibers, an increase in the size and number of the dermal cysts, and an increase in subpanniculus elastic fibers. Elastin stains of en face sections suggested that the elastic fibers in the upper dermis were exclusively derived from cells lining the epithelial root sheath and sebaceous glands. In response to UV irradiation, the elastic fibers increased in number and size, wrapping around these structures and aligning in both directions as long fibers parallel to the body axis. Electron micrographs indicated that modified epithelial cells in close proximity to the flattened epithelial cells that encircled the root sheath and sebaceous glands were the source of the elastic fibers.

Animals↗

PubMed1999

Accumulation of matrilysin (MMP-7) and macrophage metalloelastase (MMP-12) in actinic damage.

Photodamage is characterized by degradation of collagen and accumulation of abnormal elastin in the superficial dermis and several matrix metalloproteinases have previously been implicated in this process. Using immunohistochemistry and in situ hybridization, we have studied the localization of two elastolytic matrix metalloproteinases, matrilysin (matrix metalloproteinase-7) and human macrophage metalloelastase (matrix metalloproteinase-12) in solar damage. Human macrophage metalloelastase protein was detected in the superficial dermis in areas of elastotic material. Matrix metalloproteinase-7 was seen in the mid-dermis in regions with less damaged elastic fibers and morphologically better preserved collagen as well as in a band-like pattern below basal keratinocytes in eight of 18 solar elastosis. In samples taken from healthy volunteers 3 d after repeated ultraviolet A or ultraviolet B photoprovocation, occasional immunopositive cells for human macrophage metalloelastase (stromal) or matrix metalloproteinase-7 (sweat gland epithelium) were detected. In samples taken 1 d after ultraviolet B exposure, however, basal keratinocytes were matrix metalloproteinase-7 immunopositive, explaining the linear immunostaining below basal keratinocytes noted particularly in ultraviolet B treated 3 d specimens. Upregulation of metalloelastase was also demonstrated in the skin of hairless mice after repeated ultraviolet exposure. In normal skin, no staining for human macrophage metalloelastase or matrix metalloproteinase-7 was observed in association with elastin. The amount of immunoreactivity for the substrates of matrix metalloproteinase-7, versican, and tenascin, was clearly increased in solar elastosis and photoprovocated skin; versican but not tenascin was detected in the same areas as matrix metalloproteinase-7. Our results suggest that both matrix metalloproteinase-7 and -12 may contribute to remodeling of elastotic areas in sun-damaged skin.

Adult↗

PubMed1999

Antibody raised to AKAAAKAAAKA sequence on tropoelastin recognizes tropoelastin but not mature crosslinked elastin: A new tool in metabolic and structural studies of elastogenesis.

Tropoelastin, which is secreted from the cell in a soluble form, contains specific alanine rich repeat domains that are destined to form covalent desmosine and isodesmosine crosslinks in mature insoluble elastin. We raised a monospecific polyclonal antibody to a AKAAAKAAAKA synthetic peptide (AKA) which represents this alanine rich region of tropoelastin. The antibody was reactive with the original peptide antigen and purified tropoelastin, but not with mature crosslinked elastin isolated from several animal species. Conditioned media from chick aorta smooth muscle cells in culture reacted in an ELISA with the AKA antibody, but only in the presence of BAPN to block the conversion of the epsilon-amino groups to aldehydes. Immunofluorescence demonstrated that the AKA antibody decorated newly deposited tropoelastin assembled in fine fibrils in matrix produced by cultured human skin fibroblasts. EM-immunogold specifically localized this antibody to the immature elastic fibers present in fetal sheep ductus arteriosus. Moreover, immunohistochemistry demonstrated that the antibody recognized nonpolymerized tropoelastin assembled on the periphery of elastic fibers in the aorta of chicks raised on copper deficient and BAPN containing diets. These studies demonstrate that this new anti-tropoelastin antibody can be used as a useful tool to investigate elastin metabolism where it is important to distinguish between tropoelastin and mature crosslinked elastin.

Animals↗

PubMed1998

Local overexpression of TIMP-1 prevents aortic aneurysm degeneration and rupture in a rat model.

Although matrix metalloproteinases (MMPs) are expressed in abundance in arterial aneurysms, their contribution to arterial wall degeneration, dilation, and rupture has not been determined. We investigated MMP function in a rat model of aneurysm associated with arterial dilation, elastin loss, medial invasion by mononuclear inflammatory cells, and MMP upregulation. Rupture was correlated with increased gelatinase B (MMP-9) and activated gelatinase A (MMP-2). Syngeneic rat smooth muscle cells retrovirally transfected with tissue inhibitor of matrix metalloproteinases (TIMP)-1 cDNA (LTSN) or with the vector alone as a control (LXSN) were seeded onto the luminal surface of the vessels. The seeding of LTSN cells resulted in TIMP-1 local overexpression. The seeding with LTSN cells, but not LXSN cells, decreased MMP-9, activated MMP-2 and 28-kD caseinase and elastase activity, preserved elastin in the media, and prevented aneurysmal degeneration and rupture. We conclude that MMP overexpression is responsible for aneurysmal degeneration and rupture in this rat model and that local pharmacological blockade might be a reasonable strategy for controlling the formation of aneurysms in humans.

Animals↗

PubMed1998

Prevention of aneurysm development and rupture by local overexpression of plasminogen activator inhibitor-1.

BACKGROUND: Arterial aneurysms exhibit a loss of elastin and an increase in the plasminogen activators urokinase plasminogen activator (u-PA) and tissue plasminogen activator (t-PA). Because u-PA, t-PA, and plasmin have a limited proteolytic activity against elastin, the role of plasminogen activators in the aneurysmal disease is unclear. To investigate this question, we overexpressed plasminogen activator inhibitor-1 (PAI-1), an inhibitor of t-PA and u-PA, in a rat model of aortic aneurysm. METHODS AND RESULTS: Guinea pig-to-rat aortic xenografts were seeded with syngeneic Fischer 344 rat smooth muscle cells retrovirally transduced with the rat PAI-1 gene (LPSN group) or the vector alone (LXSN group). Some grafts were not seeded with cells (NO group). Western blots showed increased PAI-1 in grafts from the LPSN group compared with LXSN and NO groups. All grafts in the NO group (n=8) and 40% in the LXSN group ruptured between days 4 and 14. At 4 weeks in the LXSN group, the remaining unruptured grafts (n=6) were aneurysmal (diameter increase > or =100%), whereas in the LPSN group (n=6) none of the grafts had ruptured or were aneurysmal. Elastin was preserved in the LPSN group. t-PA, the major PA expressed in the model, was decreased in the LPSN group compared with the other groups, as determined by zymography. Quantitative zymography showed decreased levels of two matrix metalloproteinases (MMPs), a 28-kD caseinase, and activated MMP-9 in the LPSN group. CONCLUSIONS: The blockade of plasminogen activators prevents formation of aneurysms and arterial rupture by inhibiting MMP activation.

Animals↗

PubMed1998

Metalloproteinase blockade by local overexpression of TIMP-1 increases elastin accumulation in rat carotid artery intima.

We have recently demonstrated that the blockade of matrix metalloproteinases by local overexpression of the intrinsic inhibitor tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) reduces intimal hyperplasia. We now report a major change in the elastin content of the intima of rat carotid arteries seeded with TIMP-1-overexpressing smooth muscle cells. To understand the mechanism responsible for elastin accumulation, synthesis and degradation of elastin in TIMP-1 and control cell-seeded rats were measured. There were no differences in elastin mRNA or elastin synthesis, as documented by 14[C]proline incorporation between TIMP-1 and control cell-seeded arteries. In contrast, there was an increase in cross-linked elastin in the TIMP-1 group. In addition, in TIMP-1 and control rats, an elastase activity of approximately 28 kD was detected by elastin zymography and was decreased in TIMP-1 cell-seeded vessels. The 28 kD elastolytic activity was inhibited by exogenously added TIMP-1 and EDTA but not by PMSF, suggesting that it was a metalloelastase. Therefore, we have demonstrated that a shift of the proteolytic balance toward protease inhibition by TIMP-1 overexpression does not change elastin synthesis but rather changes posttranslational processing, resulting in increased elastin accumulation.

Animals↗

PubMed1997

Pulmonary structural and extracellular matrix alterations in Fischer 344 rats following subchronic phosgene exposure.

Phosgene, an acylating agent, is a very potent inducer of pulmonary edema. Subchronic effects of phosgene in laboratory animals are not well characterized. The purpose of the study was to elucidate potential long-term effects on collagen and elastin metabolism during pulmonary injury/recovery and obtain information about the concentration x time (C x T) behavior of low levels of phosgene. Male Fischer 344 rats (60 days old) were exposed either to clean air or phosgene, 6 hr/day: 0.1 ppm (5 days/week), 0.2 ppm (5 days/week), 0.5 ppm (2 days/week), and 1.0 ppm (1 day/week), for 4 or 12 weeks. A group of rats was allowed clean air recovery for 4 weeks after 12 weeks of phosgene exposure. This exposure scenario was designed to provide equal C x T product for all concentrations at one particular time point except for 0.1 ppm (50% C x T). Phosgene exposure for 4 or 12 weeks increased lung to body weight ratio and lung displacement volume in a concentration-dependent manner. The increase in lung displacement volume was significant even at 0.1 ppm phosgene at 4 weeks. Light microscopic level histopathology examination of lung was conducted at 0.0, 0.1, 0.2, and 1.0 ppm phosgene following 4 and 12 and 16 weeks (recovery). Small but clearly apparent terminal bronchiolar thickening and inflammation were evident with 0.1 ppm phosgene at both 4 and 12 weeks. At 0.2 ppm phosgene, terminal bronchiolar thickening and inflammation appeared to be more prominent when compared to the 0.1 ppm group and changes in alveolar parenchyma were minimal. At 1.0 ppm, extensive inflammation and thickening of terminal bronchioles as well as alveolar walls were evident. Concentration rather than C x T seems to drive pathology response. Trichrome staining for collagen at the terminal bronchiolar sites indicated a slight increase at 4 weeks and marked increase at 12 weeks in both 0.2 and 1.0 ppm groups (0.5 ppm was not examined), 1.0 ppm being more intense. Whole-lung prolyl hydroxylase activity and hydroxyproline, taken as an index of collagen synthesis, were increased following 1.0 ppm phosgene exposure at 4 as well as 12 weeks, respectively. Desmosine levels, taken as an index of changes in elastin, were increased in the lung after 4 or 12 weeks in the 1.0 ppm phosgene group. Following 4 weeks of air recovery, lung hydroxyproline was further increased in 0.5 and 1.0 ppm phosgene groups. Lung weight also remained significantly higher than the controls; however, desmosine and lung displacement volume in phosgene-exposed animals were similar to controls. In summary, terminal bronchiolar and lung volume displacement changes occurred at very low phosgene concentrations (0.1 ppm). Phosgene concentration, rather than C x T product appeared to drive toxic responses. The changes induced by phosgene (except of collagen) following 4 weeks were not further amplified at 12 weeks despite continued exposure. Phosgene-induced alterations of matrix were only partially reversible after 4 weeks of clean air exposure.

Animals↗

PubMed1997

The effect of ultrasound on collagen synthesis and fibroblast proliferation in vitro.

Ultrasound has been applied therapeutically to accelerate connective tissue healing although there is little direct scientific evidence to support its use. This investigation was conducted to determine the effects of ultrasound on the rate of collagen synthesis and cell proliferation using cultured fibroblasts derived from Achilles tendons of neonatal rats. Ultrasound (intensity = 0.4 W.cm-2; frequency = 1 MHz) was applied to experimental cells growing as monolayers in culture flasks. Ultrasound had no effect on the rate of collagen synthesis by control fibroblasts over a period of 9 d. The addition of vitamin C to culture media stimulated collagen synthesis to the same extent in both control and ultrasound-treated cultures. Partial digestion of cell matrices with collagenase (used to simulate injury) resulted in an approximately 20% increase in the rate of collagen synthesis. Synthesis was further increased with ultrasound treatment (50-67%). For example, after a single ultrasound treatment, the rate of collagen synthesis was 3.0 +/- 0.4 pg.micrograms-1 DNA.h-1 in cultures treated with collagenase, compared with 1.8 +/- 0.3 pg.micrograms-1 DNA.h-1 in collagenase-treated cultures not treated with ultrasound and 1.4 +/- 0.3 pg.micrograms-1 DNA.h-1 in controls. Ultrasound applied to preconfluent cultures resulted in significant increases in the rate of thymidine incorporation and DNA content. Three daily ultrasound treatments caused a 100% increase in the rate of thymidine incorporation and a 28% increase in DNA content. The results indicate that ultrasound stimulates collagen synthesis in tendon fibroblasts in response to an injury of the connective tissue matrix and that ultrasound stimulates cell division during periods of rapid cell proliferation.

Achilles Tendon↗

PubMed1996

Inhibition of neutrophil elastase suppresses the development of skin tumors in hairless mice.

In this study we investigated whether a reduction in neutrophil elastase activity in mice would alter the development of ultraviolet B or chemically induced skin tumors. A mutant strain of neutrophil elastase-deficient mice was developed by crossing beige mice with SKH 1 hairless mice. Ultraviolet irradiation three times per week for 20 wk developed an average of 10 tumors per normal mouse, whereas elastase-deficient hairless mice receiving the same treatment developed only 0.4 tumors per mouse. Benzopyrene administered topically for 20 wk resulted in an average of seven tumors per control mouse, while similar treatment to elastase-deficient hairless mice reduced the tumor count to 0.2 per mouse. Two small molecular weight elastase inhibitors, which were shown to inhibit mouse neutrophil elastase, were administered subcutaneously to normal SKH-1 mice during 16 wk of ultraviolet B exposure. Both inhibitors significantly reduced the incidence of ultraviolet B-induced tumors. When control and elastase-deficient mice were immunized with 2,4,6-trinitrochlorobenzene and oxazolone, both molecules elicited a significant contact hypersensitivity response. Ultraviolet B irradiation prior to immunization at a nonirradiated site completely suppressed the induction of contact hypersensitivity in both the normal and the deficient mice, suggesting that prevention of systemic immunosuppression was not the reason for the resistance to skin tumors observed in the elastase-deficient mice. The results suggest that neutrophil elastase can be an important factor in squamous cell tumor development.

Animals↗

PubMed1996

Postpneumonectomy lung growth: a model of reinitiation of tropoelastin and type I collagen production in a normal pattern in adult rat lung.

Elastic and collagen fibers confer recoil and tensile strength on the pulmonary vasculature, airways, alveolar walls, and pleura. These durable extracellular matrix components are primarily synthesized during lung development and growth, and are expressed at very low levels in healthy adult lung. However, reinitiation of elastin and collagen synthesis in diseases of adult lung, such as idiopathic pulmonary fibrosis, often leads to excessive or aberrant deposition of elastin and collagen which contribute to the pathophysiology of these diseases. We used an experimental model of postpneumonectomy lung growth to determine whether normal patterns of synthesis and deposition of these critical structural components can occur in the adult lung. Male Sprague-Dawley rats (250-300 grams) were subjected to left pneumonectomy and right lobectomy. The remaining lung tissue was harvested for analysis after 3, 7, or 14 days. Compensatory growth of the remaining right lung progressed throughout the time course. Total desmosine and hydroxyproline content increased in the postpneumonectomy lung, reflecting increased elastin and collagen accumulation, but both were normal in content per weight of lung tissue. Northern analysis demonstrated induction of tropoelastin and type I procollagen mRNA expression in lungs of pneumonectomy rats. In situ hybridization localized tropoelastin and type I procollagen mRNA expression to anatomical sites similar to those seen during lung development. These data indicate that the adult lung can reinitiate elastin and collagen production and deposit these extracellular matrix components in a normal pattern.

Animals↗

PubMed1996

MR889, a neutrophil elastase inhibitor, in patients with chronic obstructive pulmonary disease: a double-blind, randomized, placebo-controlled clinical trial.

We investigated whether MR889, a synthetic cyclic thiolic elastase inhibitor, administered for a period of 4 weeks to chronic obstructive pulmonary disease (COPD) patients, is well-tolerated, and whether it modifies biochemical indices of lung destruction. The study was a double-blind, randomized, placebo-controlled clinical trial in COPD patients. Thirty subjects were administered MR889 orally at a dose of 500 mg b.i.d. for 4 weeks, and 30 received placebo following the same schedule. In addition to safety parameters, MR889 efficacy was checked by a pretreatment/postreatment evaluation of levels of plasma elastin-derived peptides and urinary desmosine. There were no statistically significant differences between pretreatment and posttreatment efficacy parameter levels either in the control group or in the treated group. However, in a subset of treated patients with a short disease duration, the level of urinary desmosine dropped significantly with respect to pretreatment values (p = 0.004). We conclude that MR889 is safe to administer to COPD patients for a period of at least 4 weeks. During this time, MR889 does not modify biochemical markers of lung destruction in unselected COPD patients. Nevertheless, a subset of treated patients with fairly short disease duration showed a post-treatment reduction of desmosine urine levels, thus justifying the need for further studies to prove the efficacy of MR889 in modulating indices of lung destruction in COPD.

Aged↗

PubMed1995

Ozone-induced pulmonary functional, pathological, and biochemical changes in normal and vitamin C-deficient guinea pigs.

Since Vitamin C (ascorbate, AH2) is an important airway antioxidant and is an essential component of tissue repair, and since acute (4 hr) O3 toxicity is enhanced by AH2 deficiency, we hypothesized that longer-term O3 effects might also be increased. Female Hartley guinea pigs (260-330 g) were fed either an AH2-sufficient or an AH2-deficient diet 1 week prior to exposure, and were maintained on their respective diets during 1 week of continuous exposure to O3 (0, 0.2, 0.4, and 0.8 ppm, 23 hr/day), and during 1 week postexposure recovery in clean air. The AH2-deficient diet caused lung AH2 to drop to about 30% of control in 1 week, and to below 10% by the end of exposure and recovery. Body weight gains during exposure were decreased in the 0.8 ppm O3 group, while the AH2 deficiency began to affect body weights only during recovery. O3 caused a concentration-dependent decrease in total lung capacity, vital capacity, carbon monoxide diffusing capacity, nitrogen washout, and static compliance, while increasing forced expiratory flow rates and residual or end-expiratory volume (suggestive of pulmonary gas-trapping). The lung/body weight ratio and fixed lung displacement volume were also increased in O3-exposed animals. Lung pathology consisted of mononuclear cell and neutrophil infiltration, airway as well as alveolar epithelial cell hyperplasia, and general decrease in epithelial cell cytoplasm. Thickening of the interstitium and an apparent increase in collagen staining were seen at the terminal bronchiolar regions. Some of these effects were marginally exacerbated in AH2-deficient guinea pigs. One week postexposure to air reversed all O3-induced abnormalities, irrespective of AH2 deficiency. Whole lung hydroxyproline and desmosine were not changed at any time by either O3 or AH2 deficiency. Measurement of lung prolyl hydroxylase activity suggested that AH2 deficiency as well as O3 exposure may have increased the tissue levels of this enzyme. The lack of a significant increase in toxicity with the longer-term exposure scenario suggests that AH2 has minimal influence on other compensatory mechanisms developed over time.

Animals↗

PubMed1995

Dietary nitroprusside alleviates atherosclerosis in hypercholesterolemic Japanese quail (Coturnix coturnix japonica).

Male Japanese quail (Coturnix coturnix japonica), susceptible to cholesterol-induced atherosclerosis, were rendered hypercholesterolemic by feeding a diet containing 0.5% cholesterol in two experiments. Half the animals also received a dietary supplement of sodium nitroprusside ranging in concentration from 0.005% to 0.015%. After 10 weeks on the diets, serum was obtained for cholesterol analysis, the animals were killed, and the aortae removed and examined for the presence of atherosclerotic lesions. The number of animals having lesions and the severity of the lesions was reduced in a dose dependent manner among those animals receiving nitroprusside. Serum cholesterol was also reduced in response to increasing levels of dietary nitroprusside. These findings indicate that, in this model, dietary nitroprusside, a source of nitric oxide, can reduce the appearance and severity of atherosclerotic lesions in the aorta.

Animals↗

PubMed1995

Measurement of urinary desmosine as an indicator of acute pulmonary disease.

A modified radioimmunoassay (RIA) for desmosine in the urine was investigated as a tool for the rapid estimation of lung elastin catabolism. Cystic fibrosis (CF) and oxygen toxicity were chosen as conditions that might show altered elastin destruction. Using an antibody bound to magnetic particles the RIA was adapted to handle large numbers of samples requiring only 50 microliters or urine. The experiments show that it was not necessary to hydrolyze or extract the urine prior to assay and that collecting spot urines and normalizing the data to urine creatinine gives the same interpretation of the data as total desmosine in a 24-hour collection. Urine desmosine levels were elevated in 10 of 16 patients with CF; however, daily fluctuations were considerable in some subjects, varying as much as 5-fold and underlining the importance of assaying several consecutive days of urine in acute disorders for an accurate estimate of desmosine excretion. The RIA for desmosine is a rapid and sensitive assay that requires no sample preparation and could be applied to clinical situations that require large numbers of samples.

Acute Disease↗

PubMed1995

A role for neutrophil elastase in the progression of solar elastosis.

Hairless (SKH-1) mice were mated with Beige (C57B/bb) mice to produce a hairless mouse deficient in neutrophil elastase (hhbb). These mice were exposed to 0.09J UVB irradiation for 5 months to see if neutrophil elastase was an important factor in elastin remodeling and development of solar elastoses. Analysis of peritoneal neutrophils confirmed that the hhbb mouse was deficient in elastase, retaining only 10% as much activity as the normal littermates (hhHb). Skin MPO activity was equally elevated in all the mice receiving UVB suggesting an equal influx of inflammatory cells. The absolute breaking strength of the skin in both the hhBb and hhbb mice was not altered by UVB treatment over the 5 month exposure period. Elastin quantitated biochemically as desmosine, or visualized histologically, was increased following UVB exposure in the normal mice. In the elastase deficient mice, however, the elastin fibers appeared to be unaffected by exposure to UVB irradiation at this level. The results suggest that neutrophil elastase is an important mediator in the development of solar elastosis resulting from continued exposure to UVB irradiation.

Animals↗