Biomedical subjects

W Y Chan

Publications and source records attributed to W Y Chan.

At least 19 recordsLinked to original sources

PubMed1992

Potent V2/V1a vasopressin antagonists with C-terminal ethylenediamine-linked retro-amino acids.

We report the solid-phase synthesis and antagonistic potencies of 25 analogues (1-25) of [1-(beta-mercapto-beta,beta-pentamethylenepropionic acid),2-O-ethyl-D-tyrosine,4-valine]arginine-vasopressin (d(CH2)5D-Tyr(Et)2-VAVP) (A) and of the related Ile4 (D) and [D-Phe2,Ile4] (E) analogues, potent antagonists of the antidiuretic (V2-receptor) and of the vasopressor (V1a-receptor) responses to arginine-vasopressin (AVP). Six of these peptides (1, 13, 17, 19, 21, and 23) have the Pro-Arg-Gly-NH2 tripeptide side chain fully or partially replaced or extended by ethylenediamine (Eda). The remaining 19 peptides have L- or D-amino acids retrolinked to these six C-terminal Eda peptides. Peptides 1, 13, 17, and 19 all have the ring structure of (A). Their side-chain structures are as follows: 1, Eda; 13, Pro-Eda; 17, Pro-Arg-Eda; 19, Arg-Gly-Eda. Peptide 21 is the Pro-Arg-Eda analogue of D; peptide 23 is the Pro-Arg-Gly-Eda analogue of E. Peptide 2 is the retro-Arg analogue of 1. Its side-chain structure is Eda<--Arg. Peptides 3-6 are analogues of 2 which have the D-Tyr-(Et)2 residue replaced by L-Tyr(Et)2 (3), D-Phe2 (4), D-Ile2 (5), or D-Leu2 (6), respectively. Peptides 7-12 are analogues of 2 which have the C-terminal retro-Arg replaced in retrofashion by D-Arg (7), Gly (8), Orn (9), D-Orn (10), D-Lys (11), or Arg-Arg (12). Peptides 14-16 have D-Orn (14), D-Lys (15), and D-Arg (16) retrosubstituted to peptide 13. Peptides 18, 20, and 22 are the retro-Arg-substituted analogues of 17, 19, and 21, respectively. Peptides 24 and 25 have Val and D-Val in retrolinkage with 23, respectively. All 25 peptides were examined for agonistic and antagonistic potencies in AVP V2/V1a assays. With the exception of peptides 5 and 6, all exhibit potent anti-V1a antagonism, with anti-V1a pA2 values in the range 7.64-8.33.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗

PubMed1992

The incorporation and dispersion of cells and latex beads on microinjection into the amniotic cavity of the mouse embryo at the early-somite stage.

The ability of cells and latex beads to become incorporated into the cranial region of embryos after microinjection into the amniotic cavity was studied. Premigratory neural crest cells isolated from the lateral margins of the neuroepithelium, 3T3 fibroblast cells or H35 hepatoma cells were labelled with WGA-gold conjugates, and were then microinjected into the amniotic cavity of embryos with two to three somites in vitro. Latex beads were similarly microinjected into different groups of embryos. Incorporation of injected cells or latex beads was found in the neural crest of the midbrain and the hindbrain of 5-20% of the recipients 4 h after microinjection. At 6 and 12 h, increasingly more embryos (20-77%) were observed with labelled cells or latex beads in the crest region. While hepatoma cells and latex beads were restricted to the crest region, injected neural crest cells and fibroblasts were also found in the lateral mesenchyme, bounded laterally by the surface ectoderm and medially by the closing neural tube. By 24 h after microinjection, the injected cells or latex beads were found in 50-80% of the recipients. Neural crest cells and fibroblasts, which showed similar patterns of distribution in the embryos, were located on the dorsal aspect of the neural tube, the lateral mesenchyme, the pharyngeal arches and the regions for ganglia. Hepatoma cells and latex beads were limited to the dorsal regions of the neural tube. When microinjection was carried out in embryos with seven to eight somites, incorporation of cells or latex beads was found in 44-75% of embryos, but no dispersion of the incorporated cells or latex beads into the mesenchyme was found 24 h after microinjection. Incorporation and dispersion of cells and latex beads were not observed when embryos with 18-20 somites were used as recipients. The present study showed that neural crest or fibroblast cells when injected into the amniotic cavity could be incorporated into the neural crest, and then undergo migration along the neural crest pathways, whereas hepatoma cells and latex beads could only be incorporated. The incorporation and migration of the exogenous tissues are related to the formation and the accessibility of the neural crest in the recipients.

3T3 Cells↗

PubMed1992

beta-Momorcharin, a plant glycoprotein, inhibits synthesis of macromolecules in embryos, splenocytes and tumor cells.

1. beta-Momorcharin, a glycoprotein isolated from seeds of the bitter gourd, inhibited incorporation of [3H]leucine, [3H]uridine and [3H]thymidine into trichloroacetic acid-precipitable radioactivity in peri-implantation mouse embryos, mouse splenocytes with or without activation by concanavalin A, and human squamous carcinoma of the tongue and larynx, but did not affect incorporation of the aforementioned radioisotopes into mouse liver cells. 2. The results suggest that inhibition of protein, RNA and DNA biosynthesis in embryos, splenocytes and tumor cells may represent the mechanism of embryotoxic, immunosuppressive and antitumor actions of beta-momorcharin. 3. The results also suggest that in mouse liver cells biosynthesis of protein, RNA and DNA was not affected by beta-momorcharin.

Abortifacient Agents, Nonsteroidal↗

PubMed1992

Pathologic changes of gastric mucosa colonized by Helicobacter pylori.

One hundred eighty-nine consecutive gastric biopsies showing colonization by Helicobacter pylori (HP) were studied. Epigastric pain and bleeding were the clinical presentations in 167 cases (88.4%). Major endoscopic findings were gastritis (n = 72, 38.1%) and ulceration (n = 101, 53.4%). Duodenal ulcer was associated with 32 (44.4%) and 29 (28.7%) cases of gastritis and gastric ulcer, respectively. Histologically, the HP-colonized gastric epithelium showed characteristic degenerative changes that were topographically related to the bacteria but unrelated to the inflammatory infiltrate. Disintegration and loss of apical mucus with formation of epithelial pits was seen in nearly all cases. Other changes included microerosion, conventional erosion, and frank ulceration. Only the disintegration of apical mucus, epithelial pit, and microerosion were specific for HP colonization. These conditions were absent in areas not colonized by HP and in 79 consecutive HP-negative gastric biopsies seen during the same study period. The epithelial degenerative changes in HP-colonized gastric mucosa are easy to recognize in routine hematoxylin-eosin-stained sections and they could serve as histologic guides to the localization of the bacteria. It is proposed that HP-colonized gastric mucosa is a distinct pathologic entity with a pathologic spectrum ranging from active chronic gastritis to erosion and frank ulcer. Damage to the mucin-containing portion of the gastric epithelial cells appears to be the basic cytopathologic effect of HP on the gastric mucosa. As effective specific treatment for HP infection is available, identification of HP colonization in gastric biopsies should be attempted in all cases of gastritis and gastric ulcer.

Adolescent↗

PubMed1992

Proteins with abortifacient, ribosome inactivating, immunomodulatory, antitumor and anti-AIDS activities from Cucurbitaceae plants.

1. The biochemical characteristics and biological activities of eight Cucurbitaceae plant proteins designated trichosanthin (isolated from tubers of Trichosanthes kirilowii), beta-trichosanthin (isolated from tubers of Trichosanthes cucumeroides), alpha- and beta-momorcharins (isolated from seeds of Momordica charantia), momorchochin (isolated from tubers of Momordica cochinchinensis), luffaculin (isolated from seeds of Luffa acutangula) and luffin-a and luffin-b (isolated from seeds of Luffa cylindrica), were reviewed. 2. The isolation procedures for all eight proteins are based on aqueous extraction, acetone fractionation and ion exchange chromatography. Ammonium sulfate precipitation and gel filtration are steps which may be included to improve purification. 3. The proteins are basic in nature and possess a molecular weight of approx. 30,000. All except trichosanthin are glycoproteins. The content of Asx and Glx residues is high. The N-terminal amino acid residue is Asp. Their amino acid compositions and N-terminal amino acid sequences are similar. 4. Circular dichroism spectroscopic studies revealed that trichosanthin, alpha- and beta-momorcharins possess similar secondary but different tertiary structures. 5. Most of the proteins are immunologically distinct. 6. The proteins exhibit abortifacient, antitumor, ribosome inactivating and immunomodulatory activities. Trichosanthin manifests anti-human immunodeficiency virus activity.

Abortifacient Agents↗

PubMed1992

Helicobacter pylori-related gastritis and gastric ulcer. A continuum of progressive epithelial degeneration.

One hundred forty-five consecutive gastric biopsy specimens showing colonization by Helicobacter pylori (HP) were studied. Biopsy specimens were obtained from patients with the following conditions: gastric ulcer (GU; 76), active chronic gastritis (ACG; 52), GU with duodenal ulcer (DU; 10), and ACG with DU (7). The mean age of the patients in the ACG group was 8.6 years less than the patients in the GU group. Helicobacter pylori colonization and HP-induced epithelial degeneration (ED) were quantified by a grading system (grades 0 to 6) comprising both focal and global scores for bacterial density (HP grade) and severity of ED (ED grade). The ED grade was directly proportional to the HP grade in all biopsy specimens. Gastric ulcer biopsy specimens were associated with higher HP grades: HP grade more than 5 in 25 cases (32.9%) and ED grade more than 5 in 18 cases (23.6%) of GU compared with similar respective scores in 9 cases (17.9%) and 2 cases (3.8%) of ACG. The difference was due primarily to a higher global score of bacterial density and higher focal score of ED in the GU biopsy specimens. These results support the hypothesis that HP-positive ACG and HP-positive GU are lesions within a single disease spectrum. Heavy HP colonization and severe HP-induced epithelial damage are predisposing factors in ulcerogenesis. Because HP-positive ACG is probably a preulcerative state, eradication of the bacteria in HP-positive ACG might prevent subsequent GU.

Biopsy↗

PubMed1992

Myometrial oxytocin receptors and prostaglandin in the parturition process in the rat.

Parturition in rats is associated with an abrupt and marked increase in myometrial oxytocin (OT) receptor concentrations. In this study, we investigated the role of myometrial OT receptors in the initiation and the process of parturition. We produced chronic OT receptor blockade during the last 3 days of gestation by administration of a specific OT antagonist at 100 micrograms/day and 300 micrograms/day. We also suppressed OT receptor formation by inhibiting prostaglandin synthesis with naproxen sodium at 2 mg/day and 5 mg/day. We found that chronic blockade of OT receptors inhibited the uterotonic response to OT in Day 22 and Day 23 pregnant rats in a dose-dependent manner. OT antagonist treatment did not prolong the gestation period. However, the duration of parturition, fetal mortality, and the mortality incidence were increased in rats treated with the high dose of the OT antagonist compared to controls. Naproxen sodium at both dosage levels prolonged gestation by 24 h or longer, doubled the duration of parturition, and markedly increased fetal mortality and mortality incidence. Combined OT antagonist and naproxen treatment produced adverse outcomes similar to that produced by naproxen treatment alone. Myometrial OT receptor concentrations were markedly increased in all rats immediately postpartum, ranging from 210 to 425 fmol/mg protein compared to the 50 to 100 fmol/mg found in Day 21 and Day 22 pregnant rats. Correlation analyses between OT receptor concentrations and various parameters associated with gestation and parturition showed that there was a correlation between low OT receptor concentrations and long gestation period, prolonged parturition, and high fetal mortality rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin Receptor Antagonists↗

PubMed1992

Modes of Helicobacter colonization and gastric epithelial damage.

A total of 144 gastric biopsies colonized by Helicobacter-like organisms were studied under light and differential interference contrast microscopy for the modes of bacterial colonization. Biopsies were also graded for the degree of epithelial damage (epithelial-damage-grade: 0 to 6, in ascending order of severity) and density of Helicobacter-like organism (Helicobacter-grade: 0 to 6, in ascending order of bacterial density). Three modes of colonization were identified: free-in-mucus, surface-adhesion and intercellular colonization. Because light microscopy cannot definitely prove the presence of intracellular colonization, bacteria located between cells and below the apical cell border were counted together as intercellular colonization. Bacteria free-in-mucus were seen in all biopsies. Surface adhesion was seen in 50-87.9% of biopsies, without obvious correlation with the epithelial-damage- and Helicobacter-grades. The incidences of intercellular and intracellular colonization were directly proportional to the epithelial-damage- and Helicobacter-grades. Free-in-mucus as the predominant mode of colonization was mainly seen in biopsies with lower (1-3) epithelial-damage- and Helicobacter-grades. Conversely, biopsies with intercellular colonization as the predominant mode of colonization were mainly cases with higher (4-6) epithelial-damage- and Helicobacter-grades. In cases showing predominantly bacteria between cells, 69.2% had a gastric ulcer whereas only 38.8% of cases showing predominantly bacteria free-in-mucus showed ulceration (P < 0.01). These results indicate that Helicobacter-like organisms can invade and penetrate between epithelial cells. When free-in-mucus, Helicobacter-like organisms are less likely to induce epithelial damage. However, the more invasive modes of colonization (intercellular) were associated with severe epithelial damage and high Helicobacter density.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Gonadotropin bioactivities in mouse, hamster, rat and guinea pig pituitaries are largely adsorbed on concanavalin A-sepharose.

The pituitaries of mice, hamsters, guinea pigs and rats were extracted with Tris-Cl buffer and the extracts were chromatographed on Concanavalin A (ConA)-Sepharose into unadsorbed ConA I and adsorbed ConA II fractions. The ConA I fraction was subjected to gel filtration on Sephadex G-100 and fractionated into an unretarded peak and several retarded peaks. The peak with a molecular weight of approximately 40,000 (designated ConAI Sephadex fraction II) was then subjected to ion exchange chromatography on CM-cellulose and fractionated into an unadsorbed CM I and an adsorbed CM II fraction. The ConA II fraction was fractionated by ion exchange chromatography on CM-cellulose into CM I and CM II fractions. The ConA II CM II fraction was the chromatographic fraction which exhibited the highest potency in stimulating testosterone production by isolated rat Leydig cells. Its activity was much higher than the corresponding ConA I Sephadex fraction II CM II fraction which differed chromatographically only by non-adsorption on ConA-Sepharose. The ConA II CM II fraction manifested cross reactivity in a rat luteinizing hormone (LH) radioimmunoassay. The guinea pig pituitary ConA II CM II fraction also cross-reacted in a rat thyroid stimulating hormone radioimmunoassay. The ConA II fractions of hamster and guinea pig pituitary extracts demonstrated follicle stimulating hormone (FSH) activity while the corresponding ConA I fractions did not. The results suggest that the ConA II/ConA II CM II fraction contained most of the FSH and LH activities present in the pituitary extract.

Animals↗

PubMed1992

Nasopharyngeal carcinoma and retinoblastoma gene expression.

BACKGROUND: The pathogenesis of nasopharyngeal carcinoma (NPC) is not well defined yet. To evaluate oncosuppressor genes in NPC, two NPC cell lines were investigated for expression of the retinoblastoma (RB) gene. EXPERIMENTAL DESIGN: We used Western blotting to identify RB protein species, and checked the RB gene conformation by Southern blotting. We also used immunohistochemistry, in situ nucleic acid hybridization, and in situ extraction of RB protein to observe RB protein in NPC culture cells. RESULTS: Both cell lines as well as sublines could synthesize normal RB proteins of 110, 113 and 114 kilodaltons. These cells showed no RB DNA rearrangement. Most interphase cells showed variable amounts of anti-RB reaction product in their nuclei when immunostained by 13 monoclonal antibodies. However, all mitotic cells contained RB protein either in the cytosol or the chromosomes, depending upon the mitotic phase. The level of RB mRNA increased slightly in mitotic cells as compared with interphase cells. Double localization of bromodeoxyuridine and RB protein in NPC cells and localization of RB protein in synchronized NPC cells in different phases of the cell cycle revealed random RB protein expression in each individual tumor cell. Co-localization of RB mRNA and RB protein in interphase cells showed a different degree of RB message expression in each cell. Low-salt hypotonic buffer could remove a fraction of RB protein from stained interphase nuclei. A similar finding with slight variations was observed in 16 other cancer cell lines. CONCLUSIONS: These data indicate that our NPC cell lines contain no obvious RB gene rearrangement, but each cancer cell may have an abnormal expression of RB mRNA and protein. This phenomenon may also be true in other cancer cell lines with a normal RB gene.

Antibodies, Monoclonal↗

PubMed1991

Characterization of new members of the pregnancy-specific beta 1-glycoprotein family.

Three cDNAs encoding members of the pregnancy-specific beta 1-glycoprotein (PSG) family were isolated from human term placental cDNA library. All three cDNAs encode proteins with similar domain structure. There is a leader sequence of 34 amino acids followed by an N-domain of 109 amino acids. Immediately after the N-domain are one or two copies of a repeating A-domain of 93 amino acids, a B-domain of 85 amino acids and a C-domain of variable size. The proteins are highly hydrophilic. However, one of them has an 81-amino acid C-domain which is very hydrophobic and could potentially serve as a membrane attachment site. The putative cell-cell recognition tripeptide, Arg-Gly-Asp, is present in the N-domain of two of the proteins. Partial sequence of one of the cDNAs has been found in HeLa cells while cDNAs highly homologous to two of the cDNAs have been found in the fetal liver. Functional roles of the PSG proteins basing on their structure are proposed.

Amino Acid Sequence↗

PubMed1991

Cloning of the cDNA of alpha-momorcharin: a ribosome inactivating protein.

Using a lambda gt11 cDNA library constructed from the seeds of the bitter melon (Momordica charantia), we have obtained a full length cDNA containing the entire sequence of alpha-momorcharin by immunoscreening. The length of this cDNA is 1044 basepairs long and it consists of an open reading frame coding for a polypeptide of 286 amino acids. The first 23 residues of this polypeptide probably code for a signal sequence. The N-terminal sequence of the deduced protein is exactly identical to that determined by peptide sequencing. The sequence identity between alpha-momorcharin and other ribosome inactivating proteins, such as trichosanthin and ricin A chain, is high, i.e., 34-63%. Examination of the predicted secondary structure of alpha-momorcharin and trichosanthin indicates that these proteins have regions of high structural similarities and this may account for the common biological activities that they share, viz., abortificant, immunosuppressive, antitumor and inhibition of HIV-1.

Amino Acid Sequence↗

PubMed1991

Regenerative capacity of forelimb buds after amputation in mouse embryos at the early-organogenesis stage.

The ability of mouse forelimb buds at stage 1 (Wanek et al., '89a) of development to regenerate after amputation was investigated. The findings were as follows: 1. Outgrowths in the form of hillocks were found at the sites of amputation in 116 (95%) out of 122 embryos examined 24 hours after amputation. Examination of the amputated region after various intervals of time revealed that the outgrowths were established from flank tissues at the anterior and posterior borders of the wound. 2. Ectodermal thickening was found on the distal margin of the outgrowths in 21 (66%) out of 32 specimens examined. These thickenings were histologically similar to the apical ectodermal ridge (AER) present on the control limb buds. 3. Alkaline phosphatase activity was detected on the ectodermal thickening in 11 (79%) out of 14 experimental limb buds examined. The pattern of expression of alkaline phosphatase activity was similar to that observed in control limb buds. 4. There was no correlation between the size of the outgrowths and the presence of the ectodermal thickening or the enzymatic activity. The outgrowths developed despite the absence of ectodermal thickening and enzymatic activity, suggesting that the thickening and the presence of alkaline phosphatase are not crucial for the initiation and formation of the outgrowths. 5. Explants of the outgrowths, when grafted beneath adult kidney capsules, differentiated extensively into various tissues, which included bones, epiphyseal plates, skeletal muscles, and skin derivatives. Control explants also gave rise to the same spectrum of tissues. Hence, the flank tissues surrounding the site of amputation in E10 mouse embryos can regenerate to form a structure that is morphologically and histochemically similar to a limb bud and the mesenchyme within the structure is histogenetically competent to produce the variety of tissues that is normally found in the adult limb.

Alkaline Phosphatase↗

PubMed1991

A study on the regenerative potential of partially excised mouse embryonic fore-limb bud.

The ability of day E10 mouse fore-limb bud to regulate following the removal of a portion of limb tissue was investigated. A longitudinal strip of tissue, two to three somites in width and extending from the base of the limb bud to its distal tip, was excised. The embryos were then maintained in a roller culture system for periods of 6 h, 12 h or 24 h post-operatively prior to fixation and subsequent examination. The embryos were examined with scanning electron microscopy (SEM) and light microscopy. SEM revealed that about two thirds of the operated limbs grossly restored their overall morphology. The sequence of morphological changes involved in the restoration process is described. The ability of the restored limb bud to develop an apical ectodermal ridge (AER) is shown in histological sections.

Animals↗

PubMed1991

Trichosanthin induces atresia of ovarian follicles and inhibits steroidogenesis in gonadotropin-primed immature mice.

1. Immature mice were induced to ovulate by injections of pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin spaced 48 hr apart. 2. Trichosanthin (TCS), a protein purified from tubers of Trichosanthes kirilowii (Family Cucurbitaceae), was administered respectively 24 hr before, on the same day as, 24 hr after and 48 hr after the PMSG injection. 3. The results of TCS injections at different times were generally similar. The number of maturing follicles, corpora lutea and ovulated oocytes, and the ovarian weight, remained unaltered. 4. However, there was an increased incidence of follicular atresia and degeneration of ovulated oocytes, and a lowering of serum estradiol-17 beta and progesterone levels.

Animals↗

PubMed1991

Localization of pregnancy-specific beta 1-glycoprotein in the male reproductive tract of the rat by in situ hybridization.

Human pregnancy-specific beta 1-glycoprotein (PSG) is found in high concentrations in the serum of pregnant women, but also has been found in the serum of males and nonpregnant females. Northern slot-blot analysis has demonstrated the presence of PSG mRNA in a variety of tissues in the rat, with the highest levels being found in the testis. Therefore, we have investigated further the expression of PSG in the rat male reproductive tract using in situ hybridization. In testes from immature and adult rats, PSG mRNA was localized in Leydig and peritubular cells, and in the walls of the interstitial blood vessels. PSG transcripts were noted also in the tunica albuginea and in the stromal tissue of the caput and cauda epididymis, prostate, and seminal vesicle from adult rats. The function of PSG is unknown, but it has been speculated that PSG may have immunosuppressive properties or that it may serve as a paracrine regulator of growth and differentiation. It is possible, then, that PSG could contribute to the immunological privilege of the testis or that it plays a role in the cellular interactions which increasingly are being shown to be important in the regulation of male reproductive tract tissues.

Animals↗

PubMed1991

Epithelial damage by Helicobacter pylori in gastric ulcers.

On review of 136 consecutive biopsies of benign gastric ulcer, Helicobacter pylori was detected in 78 cases (57.3%). The gastric epithelium colonized by Helicobacter pylori showed a characteristic constellation of changes, including loss of apical mucous portion of individual cells, drop-out of epithelial cells, epithelial pits, erosions and cellular tufts, indicative of cellular injury and regeneration. Among the 58 Helicobacter-negative cases, similar changes were not observed in the ulcer edges, except for two cases which exhibited some cellular tufts. Thus, the topographic association of Helicobacter pylori with epithelial damage in the gastric ulcer edges in more than half of the cases suggests that this organism probably plays an aetiological role in ulcerogenesis, at least in these cases. Furthermore, the epithelial changes are so distinctive that they can serve as a helpful histological indicator for the presence of Helicobacter pylori in gastric biopsies.

Adult↗

PubMed1991

Oxytocin antagonists with changes in the Asn5 position shed light on hormone-oxytocin receptor interactions.

Since oxytocin agonists and antagonists have different structure-activity relationships, we have investigated the stereostructural and stereoelectronic requirements of the Asn5 residue in oxytocin antagonists by the synthesis of four analogues of the potent, prolonged acting oxytocin antagonist [Pen1,D-Phe2,Thr4,Orn8]-oxytocin (I) in which Asn5 was replaced respectively with Thr (II), Leu5 (III), Asp5 (IV) and Tyr5 (V). These analogues had pA2 values in the antioxytocic in vitro rat uterine assay of 7.23 (I), 7.16 (II), 6.67 (III), 7.21 (IV), and 6.76 (IV), respectively. All were also found to be weakly potent in the in vivo anti-vasopressor assay in the rat. These studies demonstrate very different structural and stereoelectronic requirements for oxytocin agonists and antagonists when they interact with the oxytocin uterine receptor.

Amino Acid Sequence↗