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Biomedical subjects

C Schwabe

Publications and source records attributed to C Schwabe.

At least 55 records · Page 3Linked to original sources
PubMed1990

Relaxin and prostaglandin on oxytocin secretion from bovine luteal cells during different stages of gestation.

The objective of this study was to determine whether bovine luteal cells from different stages of gestation secrete oxytocin and whether relaxin, cloprostenol (a potent analogue of prostaglandin F2 alpha), estradiol-17 beta, and LH can acutely alter oxytocin secretion. Bovine luteal cells (10(5)) were cultured for 24 h without treatment and with medium-hormone replacement every 24 h. Oxytocin was quantified by radioimmunoassay of the culture media. Basal oxytocin secretion was similar (22-31 pmol/l, p less than 0.05) for all stages of gestation (days 100, 145, 160, 185, 200, 210, and 240). Relaxin induced a dose-dependent suppression of oxytocin release. After 24 h of incubation, addition of 0, 16.7, 83.5, and 167 nmol/l porcine relaxin (3000 U/mg) induced 54 +/- 4, 105 +/- 16, 47 +/- 4, and 38 +/- 4 pmol/l of oxytocin in cells from 160-day-old corpora lutea and 138 +/- 12, 21 +/- 2, 19 +/- 3, and 15 +/- 2 pmol/l oxytocin in cells from 240-day-old corpora lutea. From luteal cells of 160- and 240-day-old corpora lutea, 2 micromol/l cloprostenol induced a marked increase (p less than 0.01) of 208 +/- 39 and 371 +/- 34 pmol/l oxytocin, respectively. Addition of 167 nmol/l relaxin did not prevent cloprostenol-induced oxytocin secretion during the first 48 h, but a decrease (p less than 0.05) in oxytocin occurred in day 3 cell cultures. These results indicate that cultured luteal cells obtained from different stages of gestation in cattle can secrete oxytocin and suggest a role for relaxin in the regulation of oxytocin release.

Animals↗
PubMed1990

Relaxin, oxytocin, and prostaglandin effects on progesterone secretion from bovine luteal cells during different stages of gestation.

To determine the effects of relaxin, oxytocin, and prostaglandin F2 alpha on progesterone secretion, bovine luteal cells from different stages of gestation were dispersed in Medium 199 with 200 units/ml penicillin, 1.0% kanamycin, 0.5% bovine serum albumin, and 400 units/ml collagenase. Cells (10(5) were cultured in 400 microliters of Dulbecco's modified Eagle's medium and Ham's F-12 medium containing fetal bovine serum and antibiotics, in Falcon multiwell plates, in a humidified environment of 95% O2 and 5% CO2 at 37 degrees C. Cells were cultured for 24 hr without treatment and thereafter with medium-hormone replacement every 24 hr. Progesterone was quantified from unextracted media by radioimmunoassay. Basal progesterone secretion after 24 hr was 1.81 +/- 0.14, 1.76 +/- 0.17, 0.54 +/- 0.49, and 0.57 +/- 0.21 pg/ml per viable luteal cell from 145-, 165-, 185-, and 240-day-old corpora lutea, respectively. Basal progesterone secretion increased (P less than 0.05) with time in culture. Relaxin induced a dose-dependent (greater than 100 ng/ml) increase in progesterone release, compared with the controls. Oxytocin and prostaglandin F2 alpha induced greater release (P less than 0.05) of progesterone than relaxin at all stages of gestation, but progesterone release was dependent on the stage of gestation and the duration in culture. Luteinizing hormone (100 ng/ml) stimulated whereas 17 beta-estradiol (50 ng/ml) inhibited progesterone secretion by luteal cells at all stages of gestation examined. Relaxin obliterated the prostaglandin- and oxytocin-induced progesterone secretion by bovine luteal cells from 145 to 214 days of gestation. Thus, relaxin, cloprostenol, and oxytocin regulate progesterone production by cultured bovine luteal cells, but hormone secretion was dependent on the stage of gestation.

Animals↗
PubMed1990

Monobiotinylated relaxins. Preparation and chemical properties of the mono(biotinyl-epsilon-aminohexanoyl) porcine relaxin.

Biotinylated porcine relaxins were synthesized and purified to homogeneity. Native porcine relaxin was reacted with biotinyl-epsilon-aminohexanoic acid-N-hydroxysuccinimide ester and the resulting mixture was separated by either ion exchange chromatography on CM-cellulose at pH 5.5 or reversed-phase high performance liquid chromatography. All four possible monosubstituted relaxin derivatives, with substitutions in N alpha A1, N epsilon A7, N epsilon A16, and N epsilon B8, were obtained. All derivatives were fully biologically active and comparative circular dichroism spectroscopy showed no significant differences in their secondary structure.

Amino Acid Sequence↗
PubMed1989

Cetacean relaxin. Isolation and sequence of relaxins from Balaenoptera acutorostrata and Balaenoptera edeni.

The tendency toward extremely high variability among relaxins derived from purportedly closely related species has come to an abrupt end with the discovery of quasi-porcine relaxin in the minke whale (Balaenoptera acutorostrata) and the Bryde's whale (Balaenoptera edeni). An aqueous abstract of the corpora lutea of the two baleen whales contained significant amounts of relaxin-like activity as determined by a mouse bioassay and by cross-reactivity with anti-pig relaxin antibodies. The activity could be isolated and purified to homogeneity. Sequence analysis revealed that both whale relaxins differed from each other by about 3 residues, whereas the relaxin of B. edeni differed at only one position from that of pig relaxin. The similarity appears to include even the chain length heterogeneity observed at the C-terminal end of the B chain in porcine relaxin which is produced by a peculiar mode of connecting peptide removal from the pro-hormone. This finding may well represent one of the better documented challenges to the current paradigm of molecular evolution.

Amino Acid Sequence↗
PubMed1989

Sneddon's syndrome: clinical course and outcome.

Fifteen patients with Sneddon's syndrome presenting since 1979 were re-examined. After a neurological examination, an orienting test of mental ability as well as an electroencephalogram were performed in all patients. In 10 of the 15 patients computed tomography of the brain was performed, too. Preceding reports and the results of the present study have been used to discuss the characteristics and prognosis of Sneddon's syndrome.

Adult↗
PubMed1989

Relaxin regulates oxytocin secretion in late-pregnant beef heifers.

The effects of porcine relaxin (3000 units/mg) on oxytocin (OT) and progesterone secretion were studied in beef heifers on Day 274 (10 days before expected parturition). Heifers (n = 11) were randomly assigned to three treatments: relaxin iv infusions combined with im injection (RLX-INF, 9000 units), relaxin im injection (RLX-im, 6000 units), and phosphate-buffered saline-treated controls (PBS). RLX-INF heifers received infusions of PBS and 1000 units of relaxin for 165 min, followed by 2000 units of relaxin im and finally 2000 units of relaxin infusion followed by 4000 units of relaxin im. Endogenous relaxin (immunoreactive) in the PBS-treated group was 0.2-0.9 ng/ml peripheral plasma. For the RLX-im group, peak relaxin was 81 +/- 12 ng/ml (+/- SE) at 45 min after treatment. There were two peaks of relaxin, 18 +/- 5.3 ng/ml and 74 +/- 7.5 ng/ml, 3.5-4.5 hr apart in the RLX-INF group. Significant peak releases of OT were evident in the relaxin-treated heifers. For the RLX-im group, an OT peak (42 +/- 16 pg/ml) occurred within 30 min after relaxin treatment. For the RLX-INF heifers, 2000 and 4000 units of relaxin were associated with major peaks of 14 +/- 0.5 and 43 +/- 1.7 pg/ml OT, respectively. Basal OT plasma levels in the PBS group were 2.5-3.1 pg/ml. Mean plasma progesterone for all heifers was 6.2 +/- 2.11 ng/ml before treatment. There was a significant decrease in progesterone (-2.5 ng/ml) in the RLX-im group within 60 min after relaxin treatment and 45 min after peak OT secretion. The maximum decrease in progesterone (-3.2 +/- 0.68 ng/ml) occurred 135 min after treatment in the RLX-im group. In the RLX-INF group, 2000 units of relaxin infusion combined with 4000 units of relaxin im significantly decreased progesterone (-3.2 +/- 1.59 ng/ml) in peripheral plasma. These results clearly indicate that relaxin causes an acute peak release of oxytocin within 30 min, followed by a marked decrease in plasma progesterone concentration in late-pregnancy cattle.

Animals↗
PubMed1988

On the receptor binding site of relaxins.

Relaxin plays a critical role in viviparity and has recently been implicated as a hormone of oviparity as well. In most mammals relaxin causes the widening of the birth canal during parturition and suppresses uterine motility during pregnancy. Relaxins isolated from several species have shown a great deal of sequence variability, and speculations regarding a putative receptor interaction site have, as a consequence, varied considerably. The isolation of skate relaxin in combination with our chemical modification data enable us to suggest a unique site for the interaction of relaxin with its uterine and symphyseal receptors.

Amino Acid Sequence↗
PubMed1987

Isolation and partial amino acid sequence of three subunit species of porcine spleen ferritin: evidence of multiple H subunits.

A partial amino acid sequence for three different subunits of the iron storage protein, ferritin, has been determined. Ferritin (Mr approximately 480,000) was isolated from porcine spleen and dissociated into its component subunits (Mr approximately 20,000). The subunits, in turn, were separated into three fractions by reversed-phase HPLC. The fractions appeared to be of equal size by sedimentation velocity, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and size-exclusion chromatography in 6 M guanidinium chloride. All three fractions were shown to be monomeric and to have no covalently attached carbohydrate (J. F. Collawn et al. (1984) Arch. Biochem. Biophys. 233, 260-266). Determination of the amino acid sequence of the C-terminal 70-80 residues from each of the fractions demonstrated three different sequences. Comparison with human liver H and L subunit sequences indicates that two of the porcine ferritin subunits are H-type subunits and one is an L-type subunit. Application of the Chou-Fasman algorithm on the three partial sequences suggests that these respective regions from each of the three subunits would probably adopt the same conformation.

Amino Acid Sequence↗
PubMed1987

Relaxin structure. Quasi allosteric effect of the NH2-terminal A-chain helix.

The NH2-terminal heptapeptide in the relaxin A-chain (Arg-Met-Thr-Leu-Ser-Glu-Lys) has been replaced by chemical means with three different helix-promoting peptides (Arg-Met-Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala, and the insulin segment Gly-Ile-Val-Glu-Gln). The partially protected NH2 terminally shortened relaxin derivative (N epsilon A16,N epsilon B8-bis(methyl-sulfonylethyloxycarbonyl)des-ArgA1,MetA2 , ThrA3,LeuA4,SerA5,GluA6,LysA7-B29-relaxin) has been prepared by a combination of cyanogen bromide digestion and Edman degradation of the epsilon-amino-protected derivative followed by mixed anhydride coupling with the synthetic peptides. All three derivatives have been isolated and purified by high performance liquid chromatography. Whole relaxins shortened at the NH2 terminus of the A-chain by 4 or more amino acid residues are biologically inactive in the mouse pubic symphysis assay (Büllesbach, E. E., and Schwabe, C. (1986) Biochemistry 25, 5998-6004). The introduction of the artificial peptides causes significant biological activity to reappear (about 30%). The loss of structural integrity of relaxins shortened by 4 or more residues of the A-chain NH2 terminus as observed by circular dichroism spectroscopy is largely reversed by the addition of the synthetic peptides. Our results suggest that no single amino acid in the NH2-terminal region of the A-chain is functionally important but that the presence of a helix is required for biological activity.

Allosteric Regulation↗
PubMed1987

Relaxin from an oviparous species, the skate (Raja erinacea).

An acid-acetone extract prepared from ovaries of the skate, Raja erinacea, contained a weakly crossreacting molecule when tested in a pig relaxin radioimmunoassay. The material was isolated and purified to homogeneity by ion exchange chromatography, molecular exclusion chromatography, and HPLC. Analytical tests proved the molecule to consist of two chains and to have a molecular weight of 7,500. Sequence analyses of the A and B chains yielded the following sequence: Glu-Glu-Lys-Met-Gly-Phe-Ala-Lys-Lys-Cys-Cys-Ala-Ile-Gly-Cys-Ser-Thr-Glu- Asp-Phe-Arg-Met-Val-Cys and Arg-Pro-Asn-Trp-Glu-Glu-Arg-Ser-Arg-Leu-Cys-Gly-Arg-Asp-Leu-Ile-Arg-Ala- Phe- Ile-Tyr-Leu-Cys-Gly-Gly-Thr-Arg-Trp-Thr-Arg-Leu-Pro-Asn-Phe-Gly-Asn-Tyr- Pro-Ile-Met respectively. Skate relaxin has 0.2% of the activity of B29 pig relaxin in the symphysis pubis assay and 0.5% in the mouse uterine muscle strip contraction inhibition assay.

Amino Acid Sequence↗
PubMed1987

Induction of parturition, progesterone secretion, and delivery of placenta in beef heifers given relaxin with cloprostenol or dexamethasone.

Sixty primiparous beef heifers from a crossbreeding study were used to examine the effects of inducing parturition with relaxin (3,000 U/mg) combined with cloprostenol (500 micrograms, i.m., n = 30) or dexamethasone (20 mg, i.m., n = 30) at Day 273, 10 +/- 1 days before expected parturition (Day 283). Heifers were assigned at random within cloprostenol and dexamethasone groups to receive relaxin (1 mg, n = 5/treatment), i.m. or in the cervical os (OS), at 0 h (the same time as cloprostenol and dexamethasone) or 24 h later. Eleven and six first-calving heifers and sixteen and nine second-calving cows also received cloprostenol + relaxin and cloprostenol + phosphate-buffered saline, respectively. Radioimmunoassay of daily plasma samples indicated an abrupt decrease in progesterone with time (p less than 0.001), from 7.5 +/- 0.50 to 1.0 +/- 0.30 ng/ml (mean +/- SE) within 48 h for all groups. The mean rate of progesterone decrease (ng/ml in 24 h) was accelerated (p less than 0.01) in relaxin-treated heifers (5.3 +/- 0.36), in contrast to dexamethasone- and cloprostenol-treated control heifers (2.8 +/- 0.40). Relaxin combined with cloprostenol or dexamethasone shortened the calving period in these heifers by reducing the interval between treatment and calving (33 vs. 56 h; p less than 0.01). The incidence and duration of retained placenta were reduced by 22 vs. 75% and 14 vs. 34 h for relaxin combined with cloprostenol or dexamethasone as compared with cloprostenol- or dexamethasone-treated controls, respectively (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Acute decrease in progesterone and increase in estrogen secretion caused by relaxin during late pregnancy in beef heifers.

Purified porcine relaxin (3000 U/mg) was administered im (RLX-IM; 1 mg; n = 2) and in the cervical os (RLX-OS; 1 mg; n = 2) on day 273 (approximately 10 days before parturition normally occurs) of gestation to determine the profiles of immunoreactive relaxin and its effects on progesterone, estrone (E1), and 17 beta-estradiol (17 beta-E2) secretion in peripheral blood plasma of beef heifers. Controls received either 0.01 M PBS (1 ml, im; n = 2) or 0.01 M gel-PBS (gel; 1 ml, os; n = 2) in cervical os. One relaxin-treated (im) heifer calved at 4 h and 36 min after treatment; thus, data from this heifer were not included in subsequent analysis. Relaxin-treated heifers showed an acute elevation in relaxin, a precipitous decrease in progesterone, and a significant (P less than 0.05) elevation of E1 and 17 beta-E2. Plasma relaxin levels were 4.95, 1.5, and 0.24 ng/ml at 0.5 h in RLX-IM, RLX-OS, and control animals, respectively. Peripheral plasma relaxin peaked between 23-31 ng/ml 1-2.5 h before returning to less than 0.5 ng/ml 5-12 h after treatment. Relaxin administration accounted for 70%, 73%, and 58% of the progesterone, E1, and 17 beta-E2 variability between treatments, respectively. An abrupt decrease (P less than 0.01) in progesterone preceded the rises (P less than 0.05) in E1 and 17 beta-E2 at 1.5, 2-2.5, and 2-3.5 h, respectively. Maximum progesterone deviations from the pretreatment mean concentration were -5.43, -3.05, and -0.92 ng/ml for RLX-IM, RLX-OS, and controls. Progesterone rebounded from 36% to 61% and 62% to 79% of respective pretreatment means for RLX-IM and RLX-OS. Peak elevation of E1 was 407.3, 306.5, and 71.5 pg/ml and that of 17 beta-E2 was 82.2, 35.8, and 7.8 ng/ml for RLX-IM, RLX-OS, and controls, respectively. These results provide strong evidence that a pharmacological dosage of relaxin induces an acute depression of progesterone secretion beginning within 90 min in beef heifers during late pregnancy. We suggest that these early and marked luteolytic effects of relaxin on progesterone secretion in cattle could be by direct or indirect actions via mechanisms that are yet unknown.

Animals↗
PubMed1986

Isolation, purification, and the sequence of relaxin from spiny dogfish (Squalus acanthias).

A relaxin-like molecule has been isolated from the ovaries of the spiny dogfish (Squalus acanthias) which consists, like porcine relaxin, of two chains linked by the insulin-type disulfide bonds. The total number of amino acids is 54 of which 24 are in the A chain and 30 in the B chain. The molecular masses, calculated from the amino acid compositions, are 2510 Da for the A chain and 3370 Da for the B chain, making a total of 5880 Da. The N-terminus of the B chain is protected by a 5-oxoproline (pyrrolidone carboxylic acid) residue which is also found in the same position in the relaxins of sand tiger shark, pig, and man, whereas the relaxin of the rat has its 5-oxoproline residue at the N-terminal of the A chain. By all available criteria, S. acanthias relaxin is a typical member of the relaxin family although the sequence homology to mammalian relaxins is limited to about 45% of its amino acid residues. In contrast, the dogfish relaxin shows about 80% homology with sand tiger shark relaxin (the first such interspecies similarity to be observed) and has about twice the biological activity (mouse pubic symphysis test) when compared to sand tiger relaxin.

Amino Acid Sequence↗
PubMed1986

Preparation and properties of porcine relaxin derivatives shortened at the amino terminus of the A chain.

Porcine relaxins shortened at the N terminus of the A chain were produced after protection of all amino groups with the base-labile [[(methylsulfonyl)ethyl]oxy]carbonyl (Msc) protecting group. The first two amino acids were removed by cyanogen bromide digestion whereby simultaneously a free alpha-amino group was generated in position A3. The resulting des-ArgA1,MetA2-N epsilon A7,N epsilon A16,N epsilon B8-tris [[[(methylsulfonyl)ethyl]oxy]carbonyl]relaxin. was further shortened by preparative Edman degradation. The shortest derivative obtained was des-ArgA1,MetA2,ThrA3,LeuA4,SerA5,GluA6 -N epsilon A7,N epsilon A16,N epsilon B8-tris[[[(methylsulfonyl)ethyl]oxy]carbonyl]relaxin. The deprotection of the derivatives in alkaline media resulted in crude des-A(1-2)- to des-A(1-6)-relaxins, which were subsequently purified by gel filtration on Sephadex G-50 superfine followed by either ion exchange chromatography on CM-cellulose at pH 5.1 or high-performance liquid chromatography on reversed-phase columns. During the CNBr digest, a side product was isolated that was identified as the corresponding homoserine ( [HseA2]relaxin) derivative. Shortened relaxin derivatives and [HseA2]relaxin were characterized by reversed-phase chromatography, electrophoresis, end-group determination, and amino acid composition. Circular dichroism studies revealed a distinct change in the structure of relaxins that were shortened by three and more amino acid residues. In the mouse interpubic ligament assay, des-A(1-2)-relaxin and [HseA2]relaxin were fully biologically active while the bioactivity of des-A(1-3)-relaxin dropped to about 50%. Relaxins shortened by four and more amino acid residues were biologically inactive.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1986

Coypu insulin. Primary structure, conformation and biological properties of a hystricomorph rodent insulin.

Insulin from a hystricomorph rodent, coypu (Myocaster coypus), was isolated and purified to near homogeneity. Like the other insulins that have been characterized in this Suborder of Rodentia, coypu insulin also exhibits a very low (3%) biological potency, relative to pig insulin, on lipogenesis in isolated rat fat-cells. The receptor-binding affinity is significantly higher (5-8%) in rat fat-cells, in rat liver plasma membranes and in pig liver cells, indicating that the efficacy of coypu insulin on receptors is about 2-fold lower than that of pig insulin. The primary structures of the oxidized A- and B-chains were determined, and our sequence analysis confirms a previous report [Smith (1972) Diabetes 21, Suppl. 2, 457-460] that the C-terminus of the A-chain is extended by a single residue (i.e. aspartate-A22), in contrast with most other insulin sequences, which terminate at residue A21. In spite of a large number of amino acid substitutions (relative to mammalian insulins), computer-graphics model-building studies suggest a similar spatial arrangement for coypu insulin to that for pig insulin. The substitution of the zinc-co-ordinating site (B10-His----Gln) along with various substitutions on the intermolecular surfaces involved in the formation of higher aggregates are consistent with the observation that this insulin is predominantly 'monomeric' in nature. The c.d. spectrum of coypu insulin is relatively similar to those of casiragua insulin and of bovine insulin at low concentration.

Amino Acid Sequence↗
PubMed1986

Pelvic development as affected by relaxin in three genetically selected frame sizes of beef heifers.

Purified porcine relaxin was administered into the cervical os on Day 278 of gestation to determine its effects on pelvic development in three genetically selected frame sizes of primiparous beef heifers. Heifers were categorized as small, medium and large frame based upon their genetic composition. Pelvic height, pelvic width and cervical dilatation were determined from Day 270 to 2 days postpartum. On Day 270, heifers were assigned at random to one of three treatments: vehicle control, n = 16; relaxin once (3,000 U), n = 14; and relaxin twice (2 times 3,000 U 12 h apart), n = 17. Each heifer-frame size was represented in each treatment. Relaxin caused marked increases in pelvic height and width, as well as in the rate of linear increase (cm/day) of these parameters (p less than 0.05). These linear increases in pelvic height were 510, 264 and 204%, and pelvic width, were 280, 213 and 204% of the respective pretreatment rates for small, medium and large heifers. The rate of linear increase in pelvic width was greater than pelvic height in all heifers, but maximal in small-frame heifers; relaxin attenuated these intrinsic differences. For small heifers, the rate of linear increase in pelvic width was 121 and 145% of increases for medium and large heifers, respectively, before treatment, and 160 and 200% after treatment. The rate of postpartum involution of pelvic width was -0.03, -0.36 and -0.50 cm/day and, for pelvic height, -0.02, -0.27 and -0.29 cm/day in small, medium and large heifers, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗