The grand multipara

Grandmultiparity (GMP) has long been considered an obstetric complication for both mother and fetus, although recent studies indicate that, with proper perinatal care, women with high-parity rates are no longer at high risk. The current study examines the outcome of delivery in 1700 women in their fifth or more delivery, as compared with two control groups: 622 primiparas and 735 multiparas (two to three previous deliveries). Excellent prenatal care was available free of charge to all parturients. Our objectives were to evaluate the management of GMP in contemporary obstetrics and to assess whether grand multiparas are still high-risk patients. The age of the grandmultiparas was significantly higher compared with with the control groups, which may explain the higher incidence among them of antenatal medical disorders, such as diabetes mellitus and hypertensive disease. No significant differences were found among the three groups for preterm or post-term births, small-for-gestational-age infants, polyhydramnios, oligohydramnios, perinatal death, fetal distress, multiple births, placenta previa, abruptio placentae or cord prolapse. Macrosomia was markedly higher in the grandmultiparas and multiparas than in nulliparas. Thus, our results indicate that good perinatal care can ensure better results in grandmultiparas, and that grandmultiparity no longer needs to be considered a high-risk obstetric category in our population.

Great grand multiparity--beyond the 10th delivery

OBJECTIVE

To investigate the perinatal outcome and obstetric complications of women delivering for the 10th time or more.

METHODS

Four hundred twenty women of great grand multiparity were analyzed in a modern health care setting and compared with our general population of obstetric patients, with regard to past history, maternal age, gestational age, mode of delivery, fetal outcome and intercurrent medical/obstetric problems.

RESULTS

The study group showed significantly lower rates of low birth weight infants and instrumental delivery. No significant difference was seen in the incidence of cesarean section, pathologic fetal presentation, maternal hypertension, gestational diabetes, hemorrhage, or perinatal morbidity or mortality. There was a slightly higher incidence of twin births compared with the general population.

CONCLUSION

It is probable that women capable of reaching their 10th delivery are basically healthy. If offered adequate perinatal care, they are not a high-risk group during subsequent deliveries.

Arthritis after mumps and measles vaccination

Measles, mumps, and rubella vaccine carries a risk of joint symptoms particularly in children under 5 years. A boy who presented with an inflamed knee after measles and mumps vaccination is reported; synovial fluid aspirated from the joint contained 4.3 x 10(9)/l leucocytes. It is thought that the mumps component is the aetiological cause of acute monoarthritis.

The treatment of rheumatic carditis: a review and meta-analysis

We performed a meta-analysis of the literature on the treatment of established rheumatic carditis to determine if corticosteroid therapy is superior to salicylates in preventing the sequela of inflammation--valvular damage. We identified 22 reports of comparative trials published since the introduction of corticosteroids in 1949. Five of the 22 studies met the criteria we established for the meta-analysis, which included using randomization and a 1-year follow-up for the presence of a new pathologic apical systolic murmur. Based on the meta-analysis, the advantage of corticosteroid treatment over salicylates in preventing a pathologic murmur at 1 year posttreatment is not statistically significant (estimated odds ratio 0.88; 95% confidence interval: 0.53 to 1.46). However, the meta-analysis is dominated by 1 large negative trial, and there was significant heterogeneity in the results obtained from the studies in the meta-analysis; thus, the question of whether corticosteroid therapy is marginally superior to salicylates for the prevention of valvular heart disease from rheumatic fever remains open.

Ultrastructural alterations of the amniocytes in 2 patients with rubella during the first trimester of pregnancy

The amniotic fluid cells of 2 patients with rubella at the 18th week of pregnancy were obtained during therapeutic abortion and examined with a transmission and a scanning electron microscope (SEM). In comparison with amniocytes of healthy women, those of rubella patients showed marked alterations, consisting of lack of heterochromatin, almost complete disappearance of the electron-dense cytoplasmic layer and membrane changes. The membrane damage was clearly demonstrated by SEM and was expressed by a decrease in the number and size of microvilli. Although more experience is needed for evaluation of the ultrastructure of the amniotic fluid cells in rubella patients, these findings may serve as an additional tool for the intrauterine diagnosis of rubella.

Density-dependent inhibition of mouse embryo fibroblast growth: involvement of IGFBP-3

Up until now the phenomenon of density dependent inhibition of growth has remained unexplained; one hypothesis suggests that autocrine growth inhibitory molecules are secreted in the medium of dense cultures and inhibit cell growth. From medium conditioned by mouse fibroblasts we purified a 45-kDa inhibitory factor which is an insulin-like growth factor binding protein (IGFBP-3). Based on different results we assumed that IGFBP-3 is a bifunctional molecule and has inhibitory function independent of its known function of binding IGF. In the present publication we attempted to verify whether IGFBP-3 is involved in DDI of growth. IGFBP-3 was secreted by mouse embryo fibroblasts (MEF). Its concentration in the medium increased with the cell density of the culture and was large at saturation density when DNA synthesis was minimum. Medium conditioned (CM) by dense culture was inhibitory compared to fresh medium and this inhibition disappeared when CM was preincubated with anti-IGFBP-3 IgG. Addition of FGFb to MEF dense cultures increased but transiently DNA synthesis which decreased as soon as 24 h after growth factor addition. By contrast accumulation of IGFBP-3 in the medium increased with time and was large at the time when DNA synthesis was minimum. Our results suggest that the rapid decrease of DNA synthesis in stimulated dense culture was the result of both depletion of the medium (particularly of FGFb) and the increase in concentration of inhibitory molecules like IGFBP-3. Addition of FGFb and preincubation of CM with anti-IGFBP-3 IgG were able to greatly reduce the inhibition.

Difference in biological effects between insulin-like growth factor binding protein 1 and 3

Insulin-like growth factor binding proteins 1 and 3 are essentially known as regulators of IGF bioactivity. However, we previously showed that IGFBP-3 was able, in chick embryo fibroblast (CEF), to 100% inhibit DNA synthesis stimulated by calf serum, while the maximal inhibition found with IGFBP-1 was 60%, suggesting a difference between the two IGFBPs in their biological functions. Results of the present work agree with this assumption: (a) Recombinant human IGFBP-3, like rat IGFBP-3, was able to 100% inhibit DNA synthesis stimulation induced by human serum, while this stimulation was 75% decreased by IGFBP-1. However, the most striking difference was observed when the effects of the two IGFBPs were compared for stimulation induced by a serum growth factor (SGF) fraction depleted in IGFs. Stimulation induced by the SFG fraction was more significantly decreased (p < 0.001) by IGFBP-3 than by IGFBP-1. The mean percent inhibition +/- SEM was 67.1 +/- 2.5 in the presence of IGFBP-3 (200 ng/ml) and 29.3 +/- 2.7 and 34.2 +/- 4 in the presence of 200 and 400 ng/ml IGFBP-1 respectively. Inhibition by 200 ng/ml IGFBP-1 and inhibition by 6 ng/ml IGFBP-3 were additive. However, inhibition by IGFBP-3 and that by IGFBP-1 were no longer additive at high concentrations of IGFBP-3, which might thus replace IGFBP-1. (b) FGF stimulation of CEF was similarly inhibition (65% and 70%) by IGFBP-1 and IGFBP-3. (c) TGF beta stimulation of CEF was more strongly decreased by IGFBP-3 (90%) than by IGFB-1 (60%).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of methotrexate on radiologic progression in juvenile rheumatoid arthritis

OBJECTIVE

To assess the effects of methotrexate (MTX) therapy on radiologic progression in juvenile rheumatoid arthritis (JRA).

METHODS

We evaluated serial wrist radiographs for carpal length in 23 JRA patients with bilateral wrist involvement, before and during MTX treatment. These carpal length measurements were compared with established norms for carpal length in a healthy pediatric population.

RESULTS

Both clinical responders to MTX (17 of 23 patients) and nonresponders (6 of 23) had decreasing carpal length prior to initiation of the treatment. Eleven of the 17 clinical responders had improved carpal length after a mean of 2.5 years of MTX treatment. All 6 clinical nonresponders had progressive loss of carpal length.

CONCLUSION

MTX treatment resulted in radiologic improvement, as measured by carpal length, in the majority of children with JRA who had a clinical response to MTX.

IGF binding protein-3 secreted by the prostate adenocarcinoma cells (PC-3): differential effect on PC-3 and normal prostate cell growth

Deregulation of growth in malignant cells has been suggested to be the result of increased secretion by these cells, of autocrine growth factors; alternatively, this deregulation has been assumed to be related to loss of sensitivity by malignant cells to secreted inhibitory molecules. The results of the present publication lend new support to both hypotheses. We recently showed that human prostate adenocarcinoma cells (PC-3 cells) secreted insulin-like growth factor binding proteins (IGFBP) of 45, 34 and 25 kDa. From medium conditioned by dense cultures of PC-3 cells, we have now purified two IGFBPs of M(r) 45 kDa and 34 kDa. The N-amino terminal sequences were determined, and it was shown that they are IGFBP-3. IGFBP-34 appeared to be a deglycosylated form of IGFBP-45. The two IGFBPs had more affinity for IGF-II than for IGF-I. IGFBP-45 and IGFBP-34 were growth-inhibitory factors of chick embryo fibroblasts (CEF): they totally inhibited DNA synthesis stimulated by serum in CEF. Our results point to a clear difference between the effects of these IGFBPs upon growth of normal prostate cells and malignant PC-3 cells. At a concentration of 150 ng/ml, they inhibited growth of normal prostate cells even in the presence of 1 microgram/ml insulin. This suggests that such inhibition was not simply the result of a decrease by the IGFBP of stimulation induced by serum IGF or IGF secreted by the cells. At a concentration of 150 ng/ml, IGFBP did not modify the growth of PC-3 cells. In contrast, it stimulated growth of PC-3 cells when added at a concentration lower than 50 ng/ml (about 1 nM). Our results thus provide new insight concerning the regulation of growth in PC-3 cells.

Endometrial suction in luteal phase as a method of late postcoital contraception

In a pilot study group of 25 women presenting in our clinic after exposure at ovulation to undesired pregnancy, endometrial suction by means of a Pipelle catheter was performed. Sixteen of the 25 women had proven fertility and 9 had never tried to conceive. The women were aged 18 to 38 years. Pathological dating of endometrial sampling verified that the patients were actually post-ovulation in all cases studied. hCG tests were performed 10 to 14 days after endometrial suction and all were negative. We conclude that endometrial suction in the luteal phase is a possible means of postcoital non-hormonal contraception, and we are currently expanding our study.

Insulin-like growth factor binding protein (IGFBP-3), an inhibitor of serum growth factors other than IGF-I and -II

Our results show that an insulin-like growth factor binding protein, IGFBP-3, purified from rat serum, is an inhibitor of chick embryo fibroblast (CEF) growth. It abolished DNA synthesis in CEF stimulated by IGF-I as well as by human serum. Rat IGFBP-3 and IDF45 (an inhibitory diffusible factor secreted by mouse cells) had the same activities, confirming that they have an intrinsic capacity to inhibit serum stimulation and may be considered as growth inhibitors. Our data show that inhibition by IGFBP-3 of serum stimulation was not simply the result of its inhibition of IGF present in the serum: 1) While anti-IGF-I IgG was able to completely inhibit stimulation induced by added IGF-I, it did not decrease stimulation induced by 1% human serum. Anti-IGF-II IgG inhibited the stimulation induced by added IGF-II, but only 25% decreased the stimulation induced by 0.7% serum. The percent inhibition was not significantly increased when the concentration of serum was decreased to 0.2%, which induced 140% stimulation of DNA synthesis; 2) stimulation by 0.2% serum was much more inhibited by IGFBP-3 than by IgG anti IGF-II; 3) after separation of IGF-I and IGF-II from serum by chromatography of acidified serum proteins on BioGel P150, the remaining serum proteins (with a molecular mass greater than 45 kDa) which were depleted in IGF-I and -II (verified by RIA determination) still stimulated DNA synthesis, and this stimulation was 80% inhibited by IGFBP-3.

Stimulation by TGFβ of chick embryo fibroblasts—Inhibition by an IGFBP-3

The multiple effects of TGF beta on cell proliferation are not well understood. Our results show that TGF beta was a good but transient mitogen for chick embryo fibroblasts. DNA synthesis was three- to fourfold increased, even at high concentrations of TGF beta. We did not show a bimodal effect. An inhibitor of cell growth, that inhibits 100% of stimulation induced by serum in CEF, was purified to homogeneity from medium conditioned by mouse 3T3 cells. This inhibitor has been shown to be an IGF-binding protein (mIGFBP-3). In the present work, this mIGFBP-3 inhibited the TGF beta stimulation by about 50%, while the stimulation induced by PDGF or insulin was not inhibited by mIGFBP-3. Furthermore, TGF beta stimulation, in the presence of a high concentration of insulin in conditions which would saturate IGF receptors, was not significantly inhibited by mIGFBP-3. All together these results suggest that a part of the mitogenic effect of TGF beta may be through increasing IGF secretion and eventually other growth factors such as PDGF (as suggested previously).

Synthesis and secretion by mouse 3T3 cells of an inhibitor of cell growth (mIGFBP-3): correlation with cell proliferation

Our results show that stimulation by serum of dense cultures of 3T3 cells rapidly induced increased synthesis of a growth inhibitor (mIGFBP-3) capable of binding IGF. mIGFBP-3 was secreted by stimulated cells immediately after its synthesis, and accumulated in the medium. Accumulation of mIGFBP-3 in the medium increased, as a function of growth factor (bFGF, PDGF, insulin) concentrations and time. bFGF was the best stimulatory factor for both DNA synthesis and accumulation of mIGFBP-3 in the first 24 h of incubation. DNA synthesis was arrested after 48 h of incubation with bFGF when accumulation of mIGFBP-3 was maximal. Since we showed that mIGFBP-3 is able to inhibit bFGF stimulation of DNA synthesis in mouse fibroblasts, it is possible that the accumulation of mIGFBP-3 induces a feedback regulation of cell growth.

Purification from transformed mouse fibroblast of a cell growth inhibitor which is an IGF-binding protein

From medium conditioned by 3T3 cells, we had previously purified an inhibitory factor of Mr 45 kDa which we termed IDF45 (inhibitory diffusible factor). The protein was able to 100% inhibit stimulation induced in CEF by 1% calf serum and to reversibly prevent cell growth. We then demonstrated that IDF45 was an IGF-binding protein. Our results suggested that IDF45 was a bifunctional molecule able to bind IGF and to inhibit DNA synthesis stimulated by this hormone, but also to inhibit stimulation of DNA synthesis induced by another growth factor in serum. Indeed, its N terminal amino acid sequence has great homology with that of IGFBP-3 and IDF45 is now proposed to be named IGFBP-3 (mouse IGF binding protein). Present results show that Ha-ras transfected 3T3 cells (EJ cells), like 3T3 cells, secrete a mIGFBP-3 molecule. In addition, transfected cells secrete a doublet of an IGF-binding protein (IGFBP-28) of Mr 28 kDa which is not secreted by untransformed 3T3 cells. IGFBP-28 has been purified and characterized in this work. Various results suggest that IGFBP-28 is not a degradation product of mIGFBP-3. Its N terminal amino acid sequence was different from that of mIGFBP-3. IGFBP-28 inhibited DNA synthesis stimulated by IGF-I, but much more IGFBP-28 protein than mIGFBP-3 was required to prevent this stimulation. In agreement with this result, IGFBP-28 has low affinity for IGF-I. In contrast, IGFBP-28 has high affinity for IGF-II. Like mIGFBP-3, IGFBP-28 was able to inhibit the stimulation induced by serum in CEF and to reversibly prevent growth, though with a specific activity lower than that of mIGFBP-3. It has also the capacity to inhibit stimulation of DNA synthesis induced by high molecular weight serum proteins depleted in IGF-I and II. In conclusion we have shown that transformation of 3T3 cells with Ha-ras induced the synthesis of a new IGF binding protein in medium conditioned by normal 3T3 cells. Our results suggest that IGFBP-28 like mIGFBP-3 is a bifunctional protein able to inhibit stimulation induced by IGF and by serum proteins different from IGFs.

An IGF binding protein is an inhibitor of FGF stimulation

We purified to homogeneity a growth inhibiting diffusible factor (IDF45) secreted by dense cultures of mouse 3T3 cells and which was able to inhibit 100% of DNA synthesis stimulated by serum in chick embryo fibroblasts (CEF) (Blat et al., 1989a). We then demonstrated that this factor was an IGF-binding protein (Blat et al., 1989b). Indeed, its N-terminal amino acid sequence was homologous to that of rat IGFBP-3. Our present results show that basic fibroblast growth factor (bFGF) induced, respectively, a fivefold and threefold increase in DNA synthesis in mouse embryo fibroblasts (MEF) and CEF. IDF-45 inhibited the stimulation induced by bFGF by about 65%, while stimulation induced by insulin, PDGF, or EGF was only weakly or not at all inhibited by IDF45. When bFGF stimulation was determined in the presence of a high concentration of insulin in conditions which minimize the effect of endogenous IGF-I or -II, this stimulation was decreased by about 50% in the presence of IDF45. This result suggests that addition of bFGF stimulates IGF secretion, thereby resulting in partial loss of inhibition, by IDF45, of bFGF stimulation.

Presence of IDF45 (mlGFBP-3) binding sites on chick embryo fibroblasts

IDF45 (inhibitory diffusible factor) a mouse insulin-like growth factor binding protein (mlGFBP-3) has been shown to 100 percent inhibit DNA synthesis stimulated by serum in chick embryo fibroblasts (CEF). Our previous results suggested that this large inhibition by IDF45 of serum stimulation was not just the result of its inhibitory activity toward IGF present in serum. The addition of Mn2+ (10(-3)M) in the incubation medium enables us to show the presence of numerous binding sites per cells (about 60,000) of mlGFBP-3. However the dissociation constant (10(-8)M) indicated that this mouse IGFBP-3 bound to the membrane with low affinity. These findings lend new support to the assumption of the bifunctional property of IGFBP-3, which would have an effect outside the cell (binding of IGF in the medium) and another effect within cells or on the surface.

IGFBP-1, an insulin like growth factor binding protein, is a cell growth inhibitor

A novel cell growth inhibitor, IDF45 (inhibitory diffusible factor), was recently purified to apparent homogeneity. It is a bifunctional molecule: able to bind Insulin like growth factor (IGF) and to 100% inhibit DNA synthesis stimulated by serum in fibroblasts. It was of interest to verify whether other members of the IGF-binding protein (IGFBP) family show the same bifunctional growth inhibitory properties. In this paper we show that purified IGFBP-1 derived from amniotic fluid is a cell growth inhibitor. In chick embryo fibroblasts, it inhibited DNA synthesis stimulated by serum. However the stimulation was maximally 60% inhibited and half of the inhibition was observed with 100ng/ml IGFBP-1. So the specific activity of IGFBP-1 is lower than that of IDF45. IGFBP-1 also reversibly prevented the CEF growth. In the same cells IGFBP-1 inhibited DNA synthesis stimulated by IGF-I. We demonstrated that the same protein IGFBP-1 is able to inhibit DNA synthesis stimulated by serum and by IGF-I. The possibility that IGFBP-1 is a bifunctional molecule is discussed.

IGF-I and IGF-binding proteins: stimulatory and inhibitory factors secreted by human prostatic adenocarcinoma cells

Deregulation of growth observed in malignant cell cultures has been assumed to be the result of increased secretion by these cells of autocrine growth factors, as well as the decreased sensitivity of these cells to inhibitory molecules which are diffused from normal or transformed cells. Our results show that PC-3 cells secreted into the medium, factors having stimulatory and inhibitory activities. We found an IGF-like molecule in medium conditioned by PC-3 cells. Its concentration was less than 1 ng/ml of conditioned medium. We demonstrated that PC-3 cells have receptors for IGF-I and are stimulated by this growth factor. However, the dose response curve shows that 1 ng/ml of IGF-I is not sufficient to indicate autocrine growth regulation by IGF of prostatic carcinoma cells. IGF-binding proteins of 90,000, 45,000, 34,000 and 28,000 molecular weight were also secreted by PC-3 cells. It is noteworthy that the secreted proteins which had the greatest inhibitory effect on chick embryo fibroblast growth also has the strongest IGF-binding activity. The probability that the IGF-binding protein secreted by PC-3 cells inhibited serum stimulation of DNA synthesis by preventing stimulation induced by IGF present in the serum is discussed. It is of interest that these IGF-binding proteins inhibited chick embryo fibroblast proliferation but did not inhibit PC-3 cells. This is in agreement with the assumption that IGF present in the medium is not an autocrine growth factor for these cells.

Differences in inhibition by IDF45 (an inhibitory diffusible factor) of early RNA synthesis stimulation induced by pp60 v-src and various mitogens

Factors inhibiting cell growth have been isolated from different cell types. However, little information is available concerning their mode of action. A novel growth inhibitory factor of 45 kDa (IDF45) was recently purified to homogeneity from medium conditioned by 3T3 cells. This molecule was able to inhibit DNA synthesis and the growth of chick embryo fibroblasts (CEF) in a reversible manner. By contrast, DNA synthesis stimulated by v-src expression in CEF was poorly inhibited by IDF45. In order to gain further insight into the IDF45 mode of action in normal and transformed CEF, we compared the effects of IDF45 on early stimulation of RNA synthesis induced in CEF by different mitogenic factors and by v-src gene expression. Stimulation, by serum, of RNA synthesis was inhibited by IDF45; however, inhibition increased when cells were preincubated with IDF45 before addition of serum and cell labeling for 2 h. IDF45 was also able to inhibit partially the stimulation of RNA synthesis induced by PMA and PDGF but was unable to inhibit stimulation of RNA synthesis induced by insulin and v-src expression. By contrast, stimulation of RNA synthesis induced by IGF-I was rapidly 100% inhibited by IDF45. The effect of IDF45 on DNA synthesis stimulated by the different mitogens was also determined and was correlated with the effect of IDF45 on RNA synthesis. These results suggest that the modes of action of IDF45 on stimulation of RNA synthesis by v-src and by insulin are similar. Our present results agree with others showing the bifunctional activity of IDF45 as an IGF-binding protein and as an inhibitory molecule in DNA stimulation induced by serum.

Inhibitory diffusible factor 45 bifunctional activity. As a cell growth inhibitor and as an insulin-like growth factor I-binding protein

From medium conditioned by 3T3 cells, we had previously purified to apparent homogeneity a novel inhibitory diffusible factor of 45 kDa (IDF45), and then determined the amino-terminal sequence. IDF45 prevented reversibly the growth of chick embryo fibroblast (CEF). In these cells, DNA synthesis stimulated by 1% serum was 50% inhibited in the presence of 45 ng/ml (1 nM) IDF45. In the present article, we show that, in CEF, DNA synthesis stimulated by IGF-I was 100% inhibited in the presence of purified IDF45. Furthermore, the 45-kDa protein (IDF45) was, after Western blotting, able to bind IGF-I. The inhibitory effect of IDF45 upon serum stimulation did not seem to be the result of its inhibitory activity upon IGF-I stimulation, since stimulation by IGF-I and serum were additive. Moreover, it was possible to dissociate the two inhibitory effects: when added to v-src transformed CEF, IDF45 was able to 100% inhibit stimulation induced by IGF-I and was unable to significantly decrease stimulation induced by serum, as was previously observed. Taken together, our results strongly suggest that IDF45 has two distinct functions, one of which was to bind IGF-I and the other to inhibit serum stimulation. Indeed, it was impossible to separate the two functions when IDF45 was purified by cation exchange fast protein liquid chromatography, a method very different from reverse-phase fast protein liquid chromatography previously used for purification to apparent homogeneity of IDF45. On the other hand, if the IGF binding activity and inhibitory activity effect upon serum stimulation were carried by two different proteins, the presence of IGF-I (in conditions where most of the 45-kDa proteins were bound to IGF-I) should not have affected the activity of the molecule inhibiting serum stimulation. However, we observed the contrary: when IDF45 was bound to IGF-I, it lost its inhibitory effect upon stimulation induced by serum. This suggests that the two activities occurred on the same protein and that IDF45 is a bifunctional protein.

Isolation and amino-terminal sequence of a novel cellular growth inhibitor (inhibitory diffusible factor 45) secreted by 3T3 fibroblasts

A growth inhibitory protein named inhibitory diffusible factor 45 (IDF45) has been purified to homogeneity from medium conditioned by dense cultures of mouse 3T3 cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of fast protein liquid chromatography-purified bioactive material showed a single band corresponding to a protein of 45 kDa. The molecule is a monomer. The pI of the molecule, as determined by isoelectric focusing, is about 6.5. The amino-terminal sequence of the protein was established as Ser-Ala-Gly-Ala-Val-Gly-Ala-Gly-Pro-Val-Val-Arg. The protein inhibits DNA synthesis in chicken embryo fibroblasts in a dose-dependent manner (ED50: 40 ng/ml, approximately 1 nM). The chemical properties of IDF45, i.e. molecular weight and amino-terminal sequence, clearly distinguish it from other known growth inhibitory proteins.