Assessment of Growth Changes in the Width of Dental Arches Caused by Removable Appliances over a Period of 10 Months in Children with Malocclusion

(1) Background: A large number of patients of orthodontic clinics are diagnosed with improper jaw relationships. Intraoral scanners have become an important part of orthodontic practice and provide an opportunity to measure the changes in the width of dental arches. The purpose of the study was to evaluate the impact of removable appliances used over a 10-month period on growth changes in children with narrowed jaw dimensions. (2) Methods: Twenty four patients were included in the study (a study group—patients, treated with removable appliances in the upper dental arch for a minimum of 10 months; a control group—patients with no craniofacial abnormalities and who did not require orthodontic treatment). A panoramic radiograph and digital intraoral scan were taken, followed by palatal width measurements in Ortho-CAD before treatment, and after a period of 10 months of treatment with removable appliances. (3) Results: After a period of 10 months of the treatment, the study group had a statistically significantly greater mean change in the anterior width of the upper dental arch than the control group. (4) Conclusions: The use of removable appliances in children with narrowed maxillary transverse dimension contributes to offsetting growth changes in comparison to children with normal occlusion.

Melanin potentiates kanamycin-induced inhibition of collagen biosynthesis in human skin fibroblasts

Ototoxicity is one of the well known side effects of kanamycin. The mechanism underlying the organ specificity of the side effect is not understood. Since many pharmacologic agents are known to form complexes with melanin and melanin is an abundant constituent of the inner ear, we investigated whether kanamycin interacts with melanin and how this process affects biosynthesis of collagen in cultured human skin fibroblasts. We found that kanamycin forms complexes with melanin. The amount of kanamycin bound to melanin increases with increase of initial drug concentration. The Scatchard plot analysis of the drug binding to melanin has shown that at least two classes of independent binding sites are implicated in the kanamycin-melanin complex formation: strong binding sites with the association constant K1 - 3 x 10(5) M(-1), and the weak binding sites with K2 - 4 x 10(3) M(-1). The number of total binding sites (n1 + n2) was calculated as about 0.64 micromol kanamycin per 1 mg melanin. We found that kanamycin induced inhibition of collagen and DNA biosynthesis (IC50 - 5 microM). Melanin at 100 microg/ml produced about 25% inhibition of DNA synthesis, but it had no effect on collagen biosynthesis in cultured fibroblasts. However, the addition of melanin (100 microg/ml) to kanamycin-treated cells (5 microM) augmented the inhibitory action of kanamycin on collagen and DNA biosynthesis. We have suggested that IGF-I receptor expression, involved in cell growth and collagen metabolism, may be one of the targets for kanamycin-induced inhibition of these processes. As shown by Western immunoblot analysis melanin augmented kanamycin-induced decrease in the expression of IGF-I receptor as well MAP kinases expression: ERK1 and ERK2. The obtained results demonstrate that melanin potentiates the inhibitory effect of kanamycin on IGF-I receptor-dependent signaling pathway in cultured fibroblasts. The data suggest a potential mechanism for the organ specificity of kanamycin-induced hearing loss in patients which may result from melanin-induced augmentation of the inhibitory effects of kanamycin on collagen and DNA biosynthesis.

Proline analogue of melphalan as a prolidase-convertible pro-drug in breast cancer MCF-7 cells

Prolidase [E.C.3.4.13.9] is ubiquitously distributed cytosolic egzopeptidase that is known to cleave imido-bond of some low molecular weight compounds coupled to L-proline. Previously we have found that conjugation of antineoplastic drug--melphalan (Mel) with proline (pro) through imido-bond resulted in formation of a good substrate for purified prolidase. Cytosolic location of prolidase in neoplastic cells suggests that proline analogue of melphalan (Mel-pro) may serve as a prolidase convertable pro-drug. We have compared several aspects of pharmacologic actions of Mel and Mel-pro in breast cancer MCF-7 cells. It has been found that Mel-pro is more effectively transported into the MCF-7 cells, evokes higher cytotoxicity, lower antimitotic activity and collagen-inhibiting activity, compared to Mel. The results suggest that targeting of prolidase as a pro-drug-converting enzyme may serve as a potential strategy in pharmacotherapy of breast cancer.

Cytotoxicity activity of L-proline analogues of anthraquinone-2-carboxylic acid in breast cancer MCF-7 cells

Although prolidase [E.C.3.4.13.9] is found in normal cells, substantially increased levels are found in some neoplastic tissues. Prolidase evokes the ability to hydrolyse the imido-bond of various low molecular weight compounds coupled to L-proline. The synthesis of three proline analogues of anthraquinone-2-carboxylic acid (1-3) has been performed. Treatment of these prodrugs with prolidase generated L-proline and the free drug, demonstrating their substrate susceptibility prolidase. The concentrations of 1, 2 and 3 needed to inhibit [1H]thymidine incorporation into DNA by 50% (IC50) in breast cancer MCF-7 cells were found to be 185 +/- 5 microM, 107 +/- 6 microM and 87 +/- 6 microM, respectively, suggesting a lower cytotoxic potency of these compounds compared to Hoechst 33228 (IC50 = 55 +/- 6 microM).

FAK-independent regulation of prolidase activity and collagen biosynthesis in MCF-7 cells

Prolidase [E.C. 3.4.13.9] plays an important role in the recycling of proline for collagen synthesis and cell growth and this enzyme activity determines the rate of collagen turnover. It has been previously suggested that prolidase activity is regulated through signal mediated by the interaction of ECM proteins, with b1 integrin receptor and that this interaction is disturbed in MCF-7 cells. The potential candidates for mediating signal transduction are the nonreceptor tyrosine kinase p125FAK and two mitogen-activated protein (MAP) kinases, ERK-1 and ERK-2, which are activated upon attachment of cells to ECM. We found that serum starvation of MCF-7 cells for 24 hours contributed to a significant decrease (by about 30%) in prolidase activity and collagen biosynthesis. These phenomena were accompanied by suppression of MAP kinases expression without any effect on the expression of FAK. The data suggest that prolidase activity and collagen biosynthesis respond to signal mediated by MAP kinases, independently of FAK expression in MCF-7 cells.

Doxycycline-induced inhibition of prolidase activity in human skin fibroblasts and its involvement in impaired collagen biosynthesis

Several lines of evidence suggest that doxycycline, a semi-synthetic derivative of tetracycline, may be a useful agent in the treatment of osteoarthritis. It inhibits collagen synthesis and collagenase activity in hypertrophic chondrocytes, slowing the process of collagen turnover. However, the mechanism of doxycycline-induced inhibition of these processes has not been established. We considered prolidase, an enzyme involved in collagen metabolism, as a possible target for the doxycycline-induced inhibition of collagen synthesis. Cultured human skin fibroblasts, specialized for collagen synthesis, were used as model cells. Prolidase [E.C. 3.4.13.9] is a manganese-dependent cytosolic exopeptidase that cleaves imidodipeptides containing C-terminal proline, thus providing large amounts of proline for collagen resynthesis. Enzyme activity is regulated through the beta1 integrin receptor. Therefore, we compared the effect of doxycycline on prolidase activity and expression, collagen biosynthesis, gelatinolytic activity and beta1 integrin expression in 24-h treated cultured human skin fibroblasts. We found that doxycycline induced coordinately inhibition of prolidase activity and collagen biosynthesis (IC50 at about 150 microg/ml) and gelatinolytic activity in cultured human skin fibroblasts. The inhibitory effect of doxycycline on the processes was not due to the cytotoxicity of this drug, as shown in the cell viability tetrazoline test. However, an inhibitory effect of the drug on DNA synthesis was observed (IC50 at about 100 microg/ml). The decrease in prolidase activity in fibroblasts treated with doxycycline was not accompanied by any differences in the amount of prolidase or beta1 integrin recovered from these cells, as shown by Western immunoblot analysis. This suggests that the doxycycline-induced down-regulation of prolidase is a post-translational event. The data presented here raise the possibility that the doxycycline-induced decrease in collagen biosynthesis is mostly due to the inhibition of prolidase activity.

Cytotoxicity and effect on collagen biosynthesis of proline analogue of melphalan as a prolidase-convertible prodrug in cultured human skin fibroblasts

Proline analogue of melphalan (MEL-PRO) was synthesised as a prodrug susceptible to the action of ubiquitously distributed, cytosolic imidodipeptidase--prolidase [E.C.3.4.13.9]. Conjugation of melphalan (MEL) with proline (PRO) through an imido-bond resulted in formation of a good substrate for prolidase. The susceptibility of MEL-PRO to the action of prolidase was found to be similar, compared to glycyl-proline--the most abundant, endogenous substrate for prolidase and about 6-fold higher compared to its substrate--glycyl-hydroxyproline. We have compared the transport of MEL and its prodrug through cell membrane, their antimitotic activity, cytotoxicity and effect on collagen biosynthesis in cultured, normal human skin fibroblasts. The prodrug was found to be more effectively transported into the cells than the free drug. Moreover, a lower cytotoxicity, antimitotic activity and inhibitory effect on collagen biosynthesis of the prodrug, compared to the free drug were observed after 24 h of incubation. MEL and MEL-PRO at concentrations of 12 microM led to the decrease in cell viability in confluent human skin fibroblasts by about 40 and 20%, respectively, during 24 h of incubation. IC50 of MEL for DNA synthesis (measured by thymidine incorporation assay) was found at about 7 microM, while MEL-PRO used at this concentration produced about 35% reduction in thymidine incorporation. Similarly, MEL and MEL-PRO used at 7 microM concentrations inhibited collagen biosynthesis in fibroblasts cultured for 24 h to about 30 and 80% of control values, respectively. However, when the cells were cultured with the drugs for 72 h, similar effects of both drugs on DNA and collagen biosynthesis were observed. The data suggest that MEL-PRO may serve as a prolidase-convertible prodrug that evokes lower cytotoxicity, antimitotic activity, and lower inhibitory effect on collagen biosynthesis in fibroblast cultures, compared to the free drug.

Estrogenic and antiestrogenic effects of raloxifene on collagen metabolism in breast cancer MCF-7 cells

We compared the effects of different concentrations of raloxifene (1, 4 and 10 microM) on collagen biosynthesis, gelatinolytic and prolidase activities and matrix metalloproteinase (MMP) expression (MMP-2 and MMP-9) in estradiol-stimulated (2 nM) breast cancer MCF-7 cells. Raloxifene inhibited in a dose-dependent manner the proliferation of MCF-7 cells, independently of the presence or absence of estradiol in the growth medium. Raloxifene at concentrations of 1 microM and 4 microM inhibited collagen biosynthesis by about 10-fold and prolidase activity by about 50%, while at a concentration of 10 microM it inhibited these processes by only about 25%. This phenomenon was accompanied by differences in gelatinolytic activity and MMP (MMP-2 and MMP-9) expression as demonstrated by zymography and Western immunoblot analysis, respectively. In estrogen-stimulated MCF-7 cells, cultured in the presence of 1 microM raloxifene, a dramatic increase in the activity of both collagenases was found. In contrast, addition of raloxifene at a concentration of 10 microM to the medium of the cells resulted in restoration of gelatinolytic activity to that found in control cells. Similarly, but at both doses (1 and 10 microM), raloxifene was able to reduce MMP-2 expression in the cells. However, when used alone (without estradiol) a concentration of 1 microM raloxifene strongly stimulated MMP-2 expression, while at a concentration of 10 microM the effect was not observed. In the case of MMP-9, only trace amounts of this gelatinase were detected, although in contrast to MMP-2, an increase in its expression was noticed at a concentration of 10 microM raloxifene. The data raise the possibility that in estrogen-stimulated MCF-7 cells, raloxifene at low concentrations (1 and 4 microM) evokes antiestrogenic effect on collagen biosynthesis and prolidase activity on the one hand, and an estrogenic effect on gelatinolytic activity on the other, while at higher concentrations (about 10 microM) it evokes an estrogenic effect on collagen biosynthesis and prolidase activity, and an antiestrogenic effect on gelatinolytic activity. Our data suggest that the effects of raloxifene on collagen synthesis, prolidase and metalloproteinase activities in breast cancer may explain its role in the prevention of breast cancer development.

Melanin potentiates daunorubicin-induced inhibition of collagen biosynthesis in human skin fibroblasts

One of the recognized side effects of antineoplastic anthracyclines is poor wound healing, resulting from an impairment of collagen biosynthesis. The most affected tissue is skin. The mechanism underlying the tissue specificity of the side effects of anthracyclines has not been established. In view of the fact that a number of pharmacologic agents are known to form complexes with melanin and melanins are abundant constituents of the skin, we determined whether daunorubicin interacts with melanin and how this process affects collagen biosynthesis in cultured human skin fibroblasts. Results indicated that daunorubicin forms complexes with melanin. Scatchard analysis showed that the binding of daunorubicin to melanin was heterogeneous, suggesting the presence of two classes of independent binding sites with K1 = 1.83 x 10(5) M(-1) and K2 = 5.52 x 10(3) M(-1). The number of strong binding sites was calculated as n1 = 0.158 micromol/mg of melanin and the number of weak binding sites as n2 = 0.255 micromol/mg of melanin. We have suggested that prolidase, an enzyme involved in collagen metabolism, may be one of the targets for anthracycline-induced inhibition of collagen synthesis. We found that daunorubicin induced inhibition of prolidase activity (IC50 = 10 microM), collagen biosynthesis (IC50 = 70 microM) and DNA biosynthesis (IC50= 10 microM) in human skin fibroblasts. Melanin (100 microg/ml) by itself produced about 25% inhibition of DNA synthesis and prolidase activity but it had no effect on collagen biosynthesis in cultured fibroblasts. However, the addition of melanin (100 microg/ml) to daunorubicin-treated cells (at IC50 concentration) augmented the inhibitory action of daunorubicin on collagen and DNA biosynthesis without having any effect on prolidase activity. The same effect was achieved when the cells were treated with daunorubicin at one-fourth of the IC50 given at 0, 6, 12 and 18 h during a 24-h incubation. The data suggest that the melanin-induced augmentation of the inhibitory effects of daunorubicin on collagen and DNA biosynthesis may result from: (i) accumulation of the drug in the extracellular matrix, (ii) gradual dissociation of the complex, and (iii) constant action of the released drug on cell metabolism. The phenomenon may explain the potential mechanism for the organ specificity of daunorubicin-induced poor wound healing in patients administered this drug.

Decreased cytotoxicity and increased antimitotic activity of a proline analogue of chlorambucil as a prodrug susceptible to the action of fibroblast's prolidase

We synthesized an proline analogue of chlorambucil (CH-pro) as a prodrug susceptible to the action of ubiquitously distributed, cytosolic imidopeptidase--prolidase [E.C.3.4.13.9]. A conjugation of chlorambucil (CH) with proline through an imido-bond resulted in the formation of a good substrate for prolidase. We have compared several aspects of biological actions of CH and its prodrug in cultured normal human skin fibroblasts. The prodrug was found to be more effectively transported into the cells than the free drug. Moreover, in opposition to CH, CH-pro had no inhibitory effect on fibroblast's prolidase activity against the endogenous substrate, glycyl-L-proline. Lower cytotoxicity and a higher antimitotic activity of the prodrug, compared to the free drug, was observed. CH and CH-pro at concentrations of 25 microM led to a 30% and 10%, decrease in cell viability in confluent human skin fibroblasts. IC50 values of CH and CH-pro for DNA synthesis was found to be 30 microM and 7 microM, suggesting higher antimitotic potency of the pro-drug compared to the free drug. CH-pro also evoked lower ability to inhibit collagen biosynthesis in cultured fibroblasts than the free drug. IC50 values of CH and CH-pro for collagen biosynthesis were found at about 15 microM and 30 microM, respectively. Targeting of prolidase as a prodrug-converting enzyme may serve as a novel strategy in pharmacotherapy of various diseases, leading to the increase in therapeutic efficacy and reduction in untoward side effects of antineoplastic agents.

Phosphorylation of prolidase increases the enzyme activity

Prolidase [EC 3.4.13.9] is a ubiquitously distributed imidodipeptidase that catalyzes the hydrolysis of C-terminal proline-containing dipeptides. The enzyme plays an important role in the recycling of proline for collagen synthesis and cell growth. Although, the increase in the enzyme activity is correlated with increased rate of collagen turnover, the mechanism by which prolidase is regulated remain largely unknown. In the present study we found that phosphorylation of fibroblast's prolidase may be an underlying mechanism for up regulation of the enzyme activity. Supporting evidence comes from the following observations: (1) immunoprecipitated prolidase was detected as a phosphotyrosine protein as shown by western immunoblot analysis, (2) tyrosine kinase inhibitor-erbstatin induced (in a dose dependent manner) a decrease in prolidase activity in cultured human skin fibroblasts, (3) anti-phosphotyrosine antibody reduced and phosphotyrosine phosphatase 1B antibody (anti-PTP 1B) increased (in a dose dependent manner) the prolidase activity in extract of fibroblast's homogenate, (4) decrease in prolidase activity from collagenase treated or serum starved fibroblasts can be partially prevented by incubating fibroblast's homogenate extract with anti-PTP 1B antibody. These results provide evidence that prolidase is phosphotyrosine enzyme and suggest that the activity of prolidase may be up regulated by the enzyme phosphorylation.

The mechanism for anthracycline-induced inhibition of collagen biosynthesis

One of the recognized side effects accompanying anti-neoplastic anthracyclines administration is poor wound healing resulting from impairment of collagen biosynthesis. However, the precise mechanism of anthracyclines-induced inhibition of collagen synthesis has not been established. We have suggested that prolidase, an enzyme involved in collagen metabolism, may be one of the targets for anthracyclines-induced inhibition of synthesis of this protein. Prolidase [EC 3.4.13.9] cleaves imidodipeptides containing C-terminal proline, providing large amount of proline for collagen synthesis. Therefore, we compared the effect of daunorubicin and doxorubicin on prolidase activity and collagen biosynthesis in confluent cultured human skin fibroblasts. We have found that daunorubicin and doxorubicin coordinately induced the inhibition of prolidase activity (IC(50)=0.3 and 10 microM, respectively) and collagen biosynthesis (IC(50)=1 and 15 microM, respectively) in cultured human skin fibroblasts. The inhibitory effect of daunorubicin or doxorubicin on prolidase activity and collagen biosynthesis was not due to anti-proliferative activity of these drugs as shown by cell viability tetrazoline test. The decrease in prolidase activity due to the treatment of confluent cells with the anthracyclines was not accompanied by any difference in the amount of enzyme protein recovered from these cells as shown by Western immunoblot analysis. It may be suggested that the inhibition is a post-translational event. Since prolidase is metalloprotease, requiring manganese for catalytic activity, and anthracyclines are known as chelators of divalent cations, we considered that the chelating ability of anthracyclines might be an underlying mechanism for the anthracyclines-induced inhibition of prolidase activity. In order to determine the ability of daunorubicin or doxorubicin to form complexes with manganese (II), potentiometric method was employed based on the measurement of protonation constant by pH-metric titrated assay. We have found that both anthracyclines form stable complexes with manganese (II). The composition of the daunorubicin-Mn(II) complex was calculated as 3:1 while that of doxorubicin-Mn(II) complex was 2:1. The constant stability value for the investigated complexes were calculated as beta(av)=(1.74+/-0.01)x10(23) for daunorubicin, and beta(av)=(1.99+/-0.025)x10(11) for doxorubicin. The higher ability of daunorubicin vs. doxorubicin to chelate manganese and inhibit prolidase activity may explain the potential mechanism for its greater potency to inhibit collagen biosynthesis.

Insulin-like growth factor-I (IGF-I) in serum and bone tissue during rat mandible fracture healing

Insulin-like growth factor-I (IGF-I) is potent stimulator of proliferation and differentiation of osteoblasts, the biosynthesis of collagen type-I and noncollagenous proteins and alkaline phosphatase activity. The role of IGF-I in bone repair has not as yet been clearly defined. The aim of the present study was the quantitative analysis of IGF-I in the serum and tissue in four phases of fractured jaws healing in rat models. IGF-I concentrations in the serum and bone extracts were determined by RIA. In respect to the control group (K) the significant increase of IGF-I occurred in the serum in phase I (211 +/- 68 ng/ml, K-153 +/- 50 ng/ml) (p < 0.05). At the tissue levels a statistically significant increase in IGF-I was confirmed in phase II (262 +/- 60 ng/g, K-182 +/- 56 ng/g) (p < 0.05). The present results demonstrate that in rat models with fractured jaws in the first two phases of healing elevated levels of IGF-I in the serum and bone tissue were observed which indicate the significant role of this polypeptide in the early healing stages.

Heparin-induced modulation of insulin like-growth factor-I action on glucose level in control and fasted rats

BACKGROUND

Insulin like-growth factor-I (IGF-I) circulates in serum bound to IGF-binding proteins (IGFBPs), which are important regulators of IGF's biological activity. There are at least two classes of BPs: a high molecular weight complex (HMWBPs) and low molecular weight species (LMWBPs), with different affinity for IGF-I. Their specific role in regulation of IGF-I bioactivity is still controversial. Since: a) IGF-I plays an important role in glucose counter regulation; b) heparin was shown to alter IGF-I affinity to BPs; and c) fasting is known to change quantity and quality of serum BPs, we decided to measure the in vivo effect of heparin on blood IGF-I, BPs and glucose levels in control and fasted rats.

MATERIALS AND METHODS

Control and fasted rats were injected i.v. with heparin (500 UI/100 g body weight) every hour during 3 hours of the experiment. Blood samples were collected before and 15 or 30 minutes after heparin injection and used for determination of free and bound IGF-I (RIA), BPs (radiometric assay) and glucose level (glucose oxidase method).

RESULTS

Heparin treatment induced hypoglycaemia in fasted rats while it induced hyperglycemia in control one. The evidence was provided that heparin dissociates IGF-I from HMWBPs complex of control rat serum (predominant one in serum of these animals) and released IGF-I in turn is bound to LMWBPs--known as inhibitors of IGF-I dependent functions. In contrast, in fasted rat serum heparin dissociates IGF-I from LMWBPs (predominant complex in serum of these animals) making IGF-I free and available to stimulate IGF-I dependent functions. Therefore in control animals, which were administered heparin, blood glucose level was elevated and in fasted animals it was decreased.

CONCLUSIONS

The data presented raise the possibility that IGF-BPs may have an important role in IGF-dependent glucose counter regulation and that heparin or heparin-like molecules may affect the process. Medical significance of heparin-induced hyperglycaemia in control animals should be taken into consideration since heparin is commonly used in clinical practice.

Inhibition of collagen biosynthesis and increases in low molecular weight IGF-I binding proteins in the skin of fasted rats

Insulin-like growth factor-I (IGF-I) is an important stimulator of collagen biosynthesis and prolidase activity in connective tissue cells. The disturbances in skin collagen metabolism (reflected by significant decrease in skin collagen content, collagen biosynthesis and prolidase activity) in fasted rats were accompanied by decrease in serum IGF-I level. Fasted rat serum was found to contain about 58% of IGF-I (101.6 +/- 15.4 ng/ml) as compared to control rat serum (175.7 +/- 19.8 ng/ml), while the skin of control and fasted rats contained similar concentrations of IGF-I (about 77 ng/g tissue). The insulin-like growth factor binding proteins (IGFBPs) of sera and tissue extracts (known to regulate IGF-I activity) were analysed by ligand blotting. In the serum of control rats one IGFBP band of about 46 kDa (corresponding to the acid-dissociated IGFBP-3) was detected. In the serum of fasted rats the 46 kDa IGFBP was not observed, however, an other IGFBP of about 30 kDa (corresponding to low molecular weight IGFBPs, e.g. IGFBP-1 or IGFBP-2) was found. The intensity of IGF-I binding to the 30 kDa IGFBP was much higher than that of IGFBP-3, found in control rat serum. Control and fasted rat skin contained similar IGFBPs, however their IGF-I binding abilities were much lower, compared to their serum counterparts. It was found that 46 kDa and 30 kDa proteins, observed in ligand blotting represent IGFBP-3 and IGFBP-1 or IGFBP-2. respectively as demonstrated by western immunoblot analysis. An increase in IGF-binding to 30 kDa IGFBP-1 and/or IGFBP-2 (known as an inhibitors of IGF-dependent functions) in the skin of fasted rats may explain the mechanism of reduced collagen biosynthesis and deposition in tissues during fasting.

Preeclampsia is associated with alterations in insulin-like growth factor (IGF)-1 and IGF-binding proteins in Wharton's jelly of the umbilical cord

Wharton's jelly is abundant in extracellular matrix, which is known as a storage site to concentrate and stabilise growth factors in the vicinity of cells. It was previously found that Wharton's jelly contains significant amounts of insulin-like growth factor (IGF)-1 and IGF-binding proteins (BPs). IGF-1 is a stimulator of biosynthetics of collagen and sulphated glycosaminoglycans. Preeclampsia (edema, proteinuria, hypertension (EPH)-gestosis) is accompanied by an accumulation of sulphated glycosaminoglycans in Wharton's jelly. IGF-1 and BPs may play an important role in such a remodelling of this tissue. It was decided to evaluate the alterations in amounts of IGF-1 and BPs in Wharton's jelly of newborns delivered by mothers with preeclampsia. Studies were performed on Wharton's jelly of 10 controls and 10 newborns delivered by mothers with preeclampsia (edema, proteinuria > 500 mg/l, arterial pressure: systolic > 140 mm Hg, diastolic > 90 mmHg). Radioimmunological techniques were employed to determine IGF-1 and IGF-BPs (BP-1 and BP-3). It was found that preeclampsia is associated with a decrease in IGF-1 and IGF-BP-1 in Wharton's jelly. A slight increase in IGF-BP-3 was found. Ligand blotting demonstrated that BP-3 (not BP-1) is a main component of Wharton's jelly, which binds IGF-1. Heparin drastically inhibited the binding of IGF-1 by BP-3. It is known from our previous studies that preeclampsia is associated with an increase in the amount of sulphated glycosaminoglycans (heparin, heparan sulphate, dermatan sulphate) in Wharton's jelly. This may be a factor, which prevents the binding of IGF-1 by BPs and facilitates the binding of IGF-1 to cells, stimulating them to produce sulphated glycosaminoglycans in Wharton's jelly.

Age-dependent changes in glycosaminoglycan content in the skin of fasted rats. A possible mechanism

It is well recognized that during fasting or aging of animals there is a decreased content of several extracellular matrix components in the skin, including glycosaminoglycans (GAGs) and decrease in biosynthesis of these macromolecules. The mechanism for the phenomena is not known. We considered skin and blood lactate as a potential candidate to control GAG metabolism in tissues. Energetic metabolism, reflected by NAD/NADH and lactate/pyruvate ratios is changed during aging or fasting and lactate inhibits at least some GAGs biosynthesis. Therefore we have compared the level of lactate and the ratios of lactate to pyruvate in the blood and skin of fasted young and fasted adult rats and correlated them with the content of skin glycosaminoglycans. It has been found that the skin of adult rats contains about 60% of GAGs found in the skin of young animals. Fasting of both groups of animals resulted in further decrease in skin GAG content. GAG content in the skin of fasted young animals was decreased by 30% while in fasted adult rats no significant differences were observed, compared to fed animals. Lactate concentration was found to be increased over 2-fold in the skin of young fasted rats, compared to young controls. The lactate concentration in adult animals was not changed during fasting, although in both cases the lactate levels were almost 3-fold higher than in young control rats. In blood, lactate concentration increased by 40% during fasting of young animals while it decreased by about 40% during fasting of adult rats. Although no differences were found in blood lactate level between young and adult rats, the ratio of lactate/pyruvate was decreased by over 2 fold in adult rats. The relative differences in mean GAG content in the skin of all experimental groups of animals were related to the similar differences in blood glucose and lactate/pyruvate ratio. Therefore not only skin lactate but also blood lactate concentrations may reflect the extent of skin GAG biosynthesis. We have noticed that increase in the ratio of skin lactate/pyruvate concentration and decrease of the ratio in the blood is accompanied by decrease in the skin GAG content. We suggest that the phenomenon may result from utilization of lactate into glucose in the Cori cycle which regulate glucose availability for GAG biosynthesis. Therefore it can be suggested that lactate may participate in inhibition of skin GAG biosynthesis and the extent of the inhibition is reflected by the ratio of lactate/pyruvate concentrations both in the skin and blood.

The mechanism of daunorubicin-induced inhibition of prolidase activity in human skin fibroblasts and its implication to impaired collagen biosynthesis

One of the recognized side effects accompanying antineoplastic anthracyclines administration is poor wound healing, resulting from impairement of collagen biosynthesis. However, the precise mechanism of anthracyclines-induced inhibition of collagen synthesis has not been established. We have suggested that prolidase, an enzyme involved in collagen metabolism may be one of the targets for anthracyclines-induced inhibition of synthesis of this protein. Prolidase [E.C. 3.4.13.9] cleaves imidodipeptides containing C-terminal proline, providing large amount of proline for collagen synthesis. We have found that daunorubicin (DNR) induced coordinately inhibition of prolidase activity (IC50 = 0.3 microM) and collagen biosynthesis (IC50 = 1 microM) in cultured human skin fibroblasts. The decrease in prolidase activity due to the treatment of confluent cells with DNR was not accompanied by any differences in the amount of the enzyme protein recovered from these cells as shown by western immunoblot analysis. Since prolidase is metaloprotease, requiring manganese for catalytic activity and anthracyclines are known as a chelators of divalent cations we considered that the chelating ability of anthracyclines may be an underlying mechanism for daunorubicin-induced inhibition of prolidase activity. In order to determine the ability of DNR to form complex with manganese (II), potentiometric method was employed based on the measurement of protonation constant by pH-metric titrated assay. We have found that DNR forms stable complex with manganese (II) and the composition of the complex of DNR with Mn (II) was calculated as 3:1. The constant stability value for the investigated complex was calculated as [beta(av) = (1.74 +/- 0.01) 10(23). The strong ability of DNR to chelate manganese may explain the potential mechanism for inhibition of prolidase activity, subsequently collagen biosynthesis and poor wound healing in patients administered DNR.

Pre-eclampsia-induced alterations in IGF-I of human umbilical cord

BACKGROUND

Extracellular matrix (ECM)-components serve as a storage site to concentrate and stabilise growth factors in the vicinity of cells. Human umbilical cord (UC) tissues contain significant amounts of IGF-I and IGF-binding proteins (BPs). IGF-I is known as a stimulator of collagen and sulphated glycosaminoglycans (GAGs) biosynthesis. Pre-eclampsia, the most common pregnancy associated syndrome, is accompanied by an accumulation of collagen and sulphated glycosaminoglycans in the UC. One may expect that IGF-I and BPs play an important role in such a remodelling of the UC tissue. For this reason it was decided to evaluate the alterations in amounts of IGF-I and BPs in UC serum and in the UC arterial wall of newborns delivered by mothers with pre-eclampsia.

MATERIALS AND METHODS

Studies were performed on the UCs of 12 control and 12 investigated newborns, delivered by mothers with pre-eclampsia (edema, proteinuria > 500 mg l-1, arterial pressure: systolic > 140 mmHg, diastolic > 100 mmHg). Radioimmunological techniques were employed to determine IGF-I and IGF-BPs (BP-1 and BP-3).

RESULTS

It was found that pre-eclampsia is associated with an increase of IGF-I concentration in the UC serum and with simultaneous decrease of its content in the umbilical cord artery (UCA). The decrease of IGF-I content in the UCA wall was accompanied by an increase of BP-3 and BP-1 in this tissue. The increase in BPs content in the UCA wall was not associated with an enhancement of IGF binding by extracts from the homogenates of arterial wall. Heparin drastically decreased the binding of IGF-I by BP-3.

CONCLUSIONS

Pre-eclampsia is associated with an increase of IGF-I-concentration in the umbilical cord blood and an elevation of BPs contents in the UCA wall. Despite a high concentration of binding proteins, IGF-I is not accumulated in this tissue. High amounts of sulphated GAGs in the UCA wall may be a factor that prevents the binding of IGF-I by BPs. Free IGF-I can easily bind to cell receptors and stimulate the cells to produce collagen and sulphated GAGs in the arterial wall.

Prolidase as a prodrug converting enzyme. III. Synthesis of proline analogues of melphalan and theirs susceptibility to the action of prolidase

The feasibility to targeting prolidase as an antineoplastic prodrug-converting enzyme has been examined. The synthesis of proline analogues of melphalan (well known antineoplastic agent) conjugated through imido-bond (potential target for prolidase action) has been performed. One of the compounds, N-[[[[(S)-carboxy]pyrrolidin-1-yl]carbonyl]methyl]-4-[bis(2-chloro ethyl) amino]-2-phenylalanine, was found as very good prolidase substrate with susceptibility over 2 fold higher compared to standard, endogenous its substrate--Gly-L-Pro. It suggests that targeting of prolidase as a proline analogue of melphalan-converting enzyme may serve as a novel strategy in therapy of neoplastic diseases.

An accumulation of IGF-I and IGF-binding proteins in human umbilical cord

It is known that extracellular matrix components (ECM) may serve as a storage site to concentrate and stabilize growth factors in the vicinity of cells. IGF-I is expressed in most fetal tissues and it is involved in anabolic effects on protein and sulphated glycosaminoglycans biosynthesis, cell proliferation and differentiation. We demonstrated that human umbilical cord (UC) tissues contain large amounts of IGF-I and IGF-I-binding proteins (BP-3 and BP-1). Particularly Wharton's jelly appears to be an abundant reservoir of IGF-I and BPs. Relatively low amount of cells and large amounts of collagen and glycosaminoglycans in UC tissues (especially in Wharton's jelly) suggest that IGF-I may play a major role in stimulation of these cells to produce ECM components. The specific BPs in these tissues may be important modulators of IGF-I action during fetal development.

Differential effect of fasting on IGF-BPs in serum of young and adult rats and its implication to impaired skin GAG content

During fasting or aging of animals there is a decreased content of skin glycosaminoglycans (GAGs). It has been found that the skin of adult rats contains about 60% of GAGs found in the skin of young animals. Fasting of both groups of animals (young and adult) resulted in decrease of GAG content. However, GAG content in the skin of fasted young rats decreased by 30% and in fasted adult rats by 15% only, compared to fed animals, respectively. The mechanism for the phenomena is not known. We considered insulin-like growth factor-I (IGF-I) as a potential candidate involved in regulation of GAG biosynthesis in both experimental models of animals. Adult rat sera were found to contain about 75% of IGF-I recovered from young rat sera. Fasting of both groups of animals resulted in dramatic decrease in serum IGF-I levels to about 50% of initial values. Since IGF-I activity and IGF-I serum half-life depends on the level of specific IGF-binding proteins (IGFBPs) we determined (i) relationship between main groups of IGFBPs, namely high molecular weight binding proteins (HMWBPs) and low molecular weight binding proteins (LMWBPs) and (ii) the amounts of IGF-I bound to respective proteins in the sera of all experimental animals. Control young rat serum was found to contain about 90% of HMWBPs and about 10% of LMWBPs as determined by ligand binding assay. In contrast, control adult rat serum contained about 60% of HMWBPs and about 40% of LMWBPs. Fasting of both groups of animals resulted in significant increase in serum levels of LMWBPs. Control young rat serum was found to contain about 8% IGF-I bound to LMWBPs while serum of control adult rats contained 18% IGF-I bound to these proteins. In sera of fasted young animals however, about 75% of the bound IGF-I was recovered from LMWBPs (about 60% of total serum IGF-I) while in sera of fasted adult animals only about 56% of the bound IGF-I was recovered from LMWBPs (about 50% of total serum IGF-I). Evidence was provided that during fasting of both groups of animals there is a significant decrease in serum BP-3 and dramatic increase in serum BP-1 concentrations, compared to respective controls. However, the concentration of BP-1 in serum of fasted young rats was increased by about 60 fold while in serum of fasted adult rats only by about 10 fold, compared to respective control animals. Negative correlation between skin GAG content and LMWBPs derived IGF-I during fasting of young (r = -0.943, p < 0.001) and adult ( r = -0.571, p < 0.01) rats was found. The data presented suggest that the effects of aging and fasting on decreased skin GAG content may be due to induction of LMWBPs that are known to (i) inhibit IGF-I dependent function and (ii) increase clearance of IGF-I from circulation. However, the effects of fasting are distinct in respect to young and adult rats suggesting that mechanisms involved in regulation of IGF-I bioactivity during aging are more complex that during fasting.

Decreased biosynthesis of glycosaminoglycans in the skin of rats with chronic diabetes mellitus

The skin of rats with experimental (streptozotocin-induced) chronic diabetes mellitus exhibits significant decrease in glycosaminoglycans (GAGs) content. In the present study we asked the question whether the decrease in GAGs content is a result of decline in GAG biosynthesis or an increase in their degradation. We demonstrated by a pulse-labeling experiments that diabetes results in a decrease of [14C]-glucosamine incorporation into both hyaluronic acid and sulphated GAGs. During the chase period, there was no significant degradation of the pulse-labeled GAGs, suggesting that the reduction of GAGs content in the skin of diabetic rats is a result of decrease in GAG biosynthesis. Especially the biosynthesis of sulphated GAGs is deeply reduced. This phenomenon may be one of the factors which impairs the wound healing in diabetic subjects.

Prolidase as a prodrug converting enzyme. II. Synthesis of proline analogue of anthraquinone-2-carboxylic acid and its susceptibility to the action of prolidase

The feasibility to targeting prolidase as an antineoplastic prodrug--converting enzyme has been examined. The synthesis of proline analogue of anthraquinone-2-carboxylic acid (potential antineoplastic agent) conjugated through imido-bond (potential target for prolidase action) has been performed. The product was found to be insoluble in aqueous solution while in the presence of 1% DMSO complete solubility of the compound was achieved. Evidence was provided that 1% DMSO does not affect prolidase activity, thus allowing for substrate susceptibility measurement in a such conditions. It has been presented that product of synthesis, N-(anthraquinone-2-carbonyl)-L-proline evokes susceptibility to the action of purified prolidase, comparable to the susceptibility of glycyl-L-proline (standard substrate for prolidase). Although insolubility of the proline analogue of anthraquinone-2-carboxylic acid in aqueous solutions limit its potential therapeutic value, the presented data suggest that prolidase may have a broader substrate specificity than thought previously. It suggests that targeting of prolidase as a prodrug-converting enzyme may serve as a potential strategy in therapy of neoplastic diseases.

Insulin-like growth factor I-dependent regulation of prolidase activity in cultured human skin fibroblasts

Prolidase [E.C.3.4.13.9] is a cytosolic exopeptidase that catalyses the hydrolysis of C-terminal proline containing dipeptides or tripeptides. The enzyme plays an important role in the recycling of proline for collagen synthesis. Increase in enzyme activity is correlated with increased rates of collagen turnover but the mechanism and endpoints by which this enzyme is regulated remain largely unknown. We have found that insulin-like growth factor-I (IGF-I), potent stimulator of collagen biosynthesis, induces prolidase activity in cultured human skin fibroblasts. Supporting evidence comes from the following observations: (1) Serum of fasted rats, (IGF-I, 72 +/- 16 ng/ml) showed about 50% reduced ability to stimulate prolidase activity and collagen biosynthesis in confluent fibroblasts in comparison to the effect of control rat serum (IGF-I, 168 +/- 29). (2) An addition of IGF-I (100 ng/ml) to fasted rat serum restored its ability to stimulate prolidase activity and collagen biosynthesis to control values. (3) In confluent human skin fibroblasts, cultured for 48 h with serum free medium prolidase activity was decreased to 50% of control cells, cultured in the presence of normal rat serum. Supplementation of serum free medium with EGF, PDGF and IGF-I (factors that can replace growth promoting activity of serum) stimulated prolidase activity to control values while the medium deprived IGF-I had no such effect. (4) The relative differences in prolidase activity due to specific treatment of confluent cells with above growth factors were accompanied by parallel differences in the amount of the enzyme protein recovered from these cells as shown by western immunoblot analysis. Thus we conclude that prolidase activity is regulated by IGF-I in confluent fibroblasts.

Prolidase as a prodrug converting enzyme I. Synthesis of proline analogue of chlorambucil and its susceptibility to the action of prolidase

The feasibility to targeting prolidase as an antineoplastic prodrug-converting enzyme has been examined. The synthesis of proline analogue of chlorambucil (well known antineoplastic agent) conjugated through imido-bond (potential target for prolidase action) has been performed. It was found that the product of synthesis, N-[4-[4-(N,N-bis(2-chloroethyl)amino) phenyl]butyryl]-L-proline is insoluble in aqueous solutions but it may be solubilized in methanol. The methanol in 30% concentration reduces catalytic activity of prolidase to 40% of values found in aqueous solution, although it allows in such conditions the measurement of substrate susceptibility to the action of this enzyme. It has been presented that product of synthesis is weakly susceptible to the action of purified prolidase, comparable to the susceptibility of glycyl-L-hydroxyproline. Although insolubility of the proline analogue of chlorambucil in aqueous solutions limit its potential therapeutic value, the presented data suggest that prolidase may have a broader substrate specificity. It suggests that targeting of prolidase as a prodrug-converting enzyme may serve as a novel strategy in therapy of various diseases.

Activity of lysosomal and nonlysosomal proteases of fibrosarcoma induced by methylcholanthrene

Activity of lysosomal (cathepsins A,B,C,D and E) and nonlysosomal proteases (cathepsin G, elastase, collagenase, prolidase, prolinase) was evaluated in fibrosarcoma induced in rats by methylcholanthrene. No differences were found in the activity of the examined proteases in tumours of different size in the external, intermediate and central spheres of these tumours. Activity of cathepsins A,B,C,D,E and G, prolidase and prolinase was higher in the fibrosarcoma and activity of collagenase and elastase was lower than in the rat skin.

Doxorubicin-induced inhibition of prolidase activity in human skin fibroblasts and its implication to impaired collagen biosynthesis

One of the recognized side effects accompanying doxorubicin administration is poor wound healing resulting from impairement of collagen biosynthesis. However, the precise mechanism of doxorubicin-induced inhibition of collagen synthesis has not been established. We considered prolidase, an enzyme involved in collagen metabolism as a possible target for doxorubicin-induced inhibition of synthesis of this protein. Prolidase [E.C.3.4.13.9] cleaves imidodipeptides containing C-terminal proline, providing large amount of proline for collagen resynthesis. Therefore, we compared the effect of doxorubicin on prolidase activity and collagen biosynthesis in cultured human skin fibroblasts. We have found that doxorubicin induces coordinately inhibition of prolidase activity (IC50 approximately 10 +/- 3 microM) and collagen biosynthesis (IC50 approximately 15 +/- 3 microM) in cultured human skin fibroblasts. The inhibitory effect of doxorubicin on prolidase activity and collagen biosynthesis was not due to cytotoxicity of this drug as shown by cell viability tetrazoline test. The decrease in prolidase activity in fibroblasts treated with doxorubicin was not accompanied by differences in the amount of the enzyme protein recovered from these cells as shown by western immunoblot analysis. It may suggest that the inhibition is a posttranslational event. The data presented here rise possibility that doxorubicin-induced decrease in collagen biosynthesis is mostly due to the inhibition of prolidase activity.

Prolidase activity and beta 1 integrin expression in moderately and poorly differentiated lung adenocarcinomas

Primary human lung adenocarcinomas were divided into two groups according to the degree of histologic differentiation: G2-moderately and G3-poorly differentiated tumors. Each group was compared with normal lung tissue in respect to prolidase activity, its ability to interact with specific antibody, free proline and beta 1 integrin subunit content as well as ability of beta 1 integrin subunit to interact with specific antibody. It was found that prolidase activity in lung adenocarcinomas G3, was significantly elevated in comparison to normal lung tissue. In lung adenocarcinoma G2 no significant changes in the enzyme activity were observed. Increase in the enzyme activity was accompanied by increase of free proline content in the tissues. The western blot analysis revealed that prolidase of lung adenocarcinomas is identical to prolidase originated in control lung tissue. It was noticed that elevated activity of prolidase in adenocarcinomas G3 was accompanied by its high expression. In respect to beta 1 integrin expression, known to play an important role in metastasis, no difference was found between adenocarcinoma groups and the control lung tissue. The presented data suggest that the level of prolidase activity in lung adenocarcinoma may serve as a more sensitive marker for the histologic degree of malignancy, than the level of beta 1 integrin expression.

Prolidase and prolinase activities in moderately and poorly differentiated lung adenocarcinoma

Prolidase (E.C.3.4.13.9) and prolinase (E.C.3.4.13.8) activities were determined in normal human lung and human lung adenocarcinomas of various degree of histologic differentiation. Since these dipeptidases were found to be enzymes catabolizing mainly collagen and simultaneously involved in the recycling of proline for collagen biosynthesis, the measurement of this protein and its degradation products in studied tissues (by hydroxyproline determination) was performed. It has been found that the activity of prolinase in G2-moderately and G3-poorly differentiated lung adenocarcinoma groups, was elevated compared to lung parenchyma and that the increase was proportional to the degree of adenocarcinoma differentiation. Prolidase activity was elevated only in G3 lung adenocarcinoma. The increase of prolidase and prolinase activities were accompanied by an increase of tissue collagen content. Collagen degradation products (CDP) represented one third of total collagen in control lung tissues while in lung adenocarcinomas the CDP represented significantly lower percentage of total tissue collagen. The results suggest that prolidase and prolinase activities may reflect: (i) degree of differentiation of lung adenocarcinoma and (ii) disturbances in tissue collagen metabolism.

Activity of lysosomal and nonlysosomal proteases and contents of protein and its degradation products in the blood serum of rats with fibrosarcoma induced by methylcholanthrene

Activity of lysosomal and nonlysosomal proteases and contents of protein and its degradation products in the blood serum of rats with methylcholantrene fibrosarcoma were evaluated. Activity of lysosomal proteases and prolidase and prolinase as well in the blood serum of rats with methylcholanthrene tumour did not differ from the activity of these enzymes in the blood serum of control rats. Only the activity of elastase and collagenase in the blood serum of rats with methylcholanthrene tumour especially with tumour of intermediate and big mass was increased. Content of total protein was decreased in the blood serum of rats with tumour of intermediate and big mass and contents of glycoproteins and alfa-amin nitrogen were increased in comparison to the blood serum of control rats.

Inhibition of prolidase activity by non-steroid antiinflammatory drugs in cultured human skin fibroblasts

Prolidase [E.C. 3.4.13.9] is a cytosolic enzyme which specifically splits imidodipeptides with C-terminal proline or hydroxyproline. This enzyme plays an important role in the recycling of proline for collagen biosynthesis and cell growth. Prolidase activity was measured in cultured human skin fibroblasts, treated with some non-steroid antiinflammatory drugs (acetyl-salicylic acid, sodium salicylate, phenylbutazone, indometacin). It was found that 24 h treatment of confluent cells with the examined drugs induced significant, dose dependent decrease in the fibroblast's prolidase activity. Simultaneously, the antiinflammatory drugs inhibited collagen biosynthesis and decreased extracellular content of this protein in extracellular matrix produced by fibroblasts. These observations suggest that non-steroid antiinflammatory drugs affect the metabolism of collagen through inhibition of prolidase activity in the collagen synthesizing cells.

Alterations in glycosaminoglycans in wounded skin of diabetic rats. A possible role of IGF-I, IGF-binding proteins and proteolytic activity

In the skin of diabetic animal tissues the amount of extracellular matrix (ECM) components is drastically decreased as a result of a reduced rate of their biosynthesis or increased degradation. In the present study we have investigated the mechanism of poor wound healing in diabetic rats. We have found that wounded skin of diabetic rats shows a significant decrease in glycosaminoglycan (GAG) content compared to that of control animals. This decrease was accompanied by significant depletion of insulin-like growth factor-I (IGF-I), known as a stimulator of GAG biosynthesis, and a distinct decrease in the content of high molecular weight IGF-binding proteins (HMW-BPs) with a simultaneous increase in low molecular weight IGF-binding proteins (LMW-BPs) in the sera of diabetic animals. Basing on determination of proteolytic activities we suggest that insulin shortage in diabetes results in increased proteolytic activity in various tissues. Proteolytic enzymes may cleave the HMW-BPs and convert them to LMW-BPs. The LMW-BPs may inactivate IGF-I and eliminate its stimulatory effects on GAG biosynthesis. The proteolytic enzymes may also digest the protein cores of proteoglycans releasing the GAGs and making them more susceptible to the action of glycosidases. These phenomena may be responsible for the observed marked decrease in GAG content in the skin of diabetic rats and disturb the wound-healing process.

Decrease in the glycosaminoglycan content in the skin of diabetic rats. The role of IGF-I, IGF-binding proteins and proteolytic activity

The results of our previous studies demonstrated that acute streptozotocin-induced diabetes in rats evoked a decrease in skin collagen content with little effect on glycosaminoglycans (GAG) content. In our present study we employed the model of chronic diabetes in order to check its effect on skin GAG content. It was found that the skin of diabetic rats showed a significant decrease in almost all the investigated GAGs by 50-70%. The decrease in heparan sulfate content was slight and statistically insignificant. We sought to determine whether the insulin-like growth factor-I (IGF-I) and IGF-binding proteins (IGF-BPs) levels are altered in animals with experimental diabetes and might contribute to the decrease in tissue GAG content. Circulating IGF-I level was found to be reduced in animals with diabetes and significant changes in serum IGF-BPs were observed. The amount of high molecular weight binding proteins (HMW-BPs) was decreased and the content of low molecular weight binding proteins (LMW-BPs), known as IGF-I inactivating substances, markedly increased. Furthermore, diabetic rats demonstrated an increase of skin proteolytic activity. We conclude that the decrease of GAG content in the skin of diabetic rats is a result of three co-existing phenomena: decreased circulating IGF-I level, increased plasma content of LMW-BPs and increased proteolytic activity of the skin.

Prolyl hydroxylase activity in liver and serum of rats and human subjects intoxicated by chronic administration of ethanol

It was found that chronic intoxication of rats with ethanol results in an increase in prolyl hydroxylase activity in liver and serum of the investigated animals. Similar effects have been observed in some alcoholic patients. We hope that the assay of prolyl hydroxylase in serum or in liver biopsy samples might be useful for the diagnosis and prognosis of the tendency of some individuals to develop liver cirrhosis.