Immunocytochemical study of the gastroenteropancreatic endocrine cells of the sheep

The gastroenteropancreatic (GEP) endocrine cells of the sheep were studied immunocytochemically and their distribution and frequency were determined. Eleven types of endocrine cells were revealed. In the abomasum, somatostatin-, gastrin-, glucagon- and glicentin-immunoreactive cells were detected with the highest frequency in the pyloric region. In the small intestine, somatostatin-, gastrin-, CCK-, motilin-, neurotensin-, secretin-, substance P-, glucagon-, glicentin- and BPP-immunoreactive cells were found and were most numerous in the duodenum except for neurotensin-, glucagon- and glicentin-immunoreactive cells which were more concentrated in the ileum. In the large intestine, somatostatin-, substance P-, glucagon-, glicentin- and BPP-immunoreactive cells were localized with the last three cell types being more concentrated in the rectum. In the pancreas, somatostatin-, glucagon-, glicentin-, BPP- and insulin-immunoreactive cells predominated within the islets and were also scattered in the exocrine portion and rarely detected in duct epithelial cells. The differences between the distribution and frequency of the GEP endocrine cells of the sheep and those of monogastric species are discussed.

An immunohistochemical and ultrastructural study of Segi's cap, a large aggregation of gut endocrine cells, in bovine fetuses

Segi's cap, a large aggregation of basal-granulated cells at the top of the intestinal villus, was studied in the proximal small intestine of bovine fetuses by histological, immunohistochemical and ultrastructural techniques. 1) Typical Segi's caps were seen in the duodenum and proximal jejunum in bovine fetuses. 2) Smaller groups of basal-granulated cells were found in the villous and partly also in the cryptal epithelium, as well as in the subepithelial lamina propria. The possible mechanism for their occurrence was discussed in connection with the fate of the cap. 3) Segi's caps were present in a neonatal calf before the suckling stage, but not in 3 or 4 week-old calves. The process of and reason for this abrupt disappearance of the caps are unknown. 4) The Segi's cap in bovine fetuses consisted mainly of argyrophil cells as demonstrated by Grimelius' and Hellerström-Hellman's silver methods. Only a few argentaffin cells were found in fetal caps using a modified Masson-Hamperl's silver method. 5) Immunohistochemically, somatostatin-, gastrin-, motilin- and secretin-immunoreactive cells were identified. 6) Four different endocrine cell types could be distinguished in the bovine Segi's cap on the basis of the ultrastructural appearance of their secretory granules.

A single gene for bovine high molecular weight and low molecular weight kininogens

A potent vasoactive peptide, bradykinin, is liberated from two distinct kininogens designated low molecular weight (LMW) and high molecular weight (HMW) kininogens. We have recently cloned and sequenced cDNAs for bovine LMW prekininogens and indicated that LMW prekininogens are encoded by two very similar but distinct mRNAs. This study concerns the structural basis for the relationship between HMW and LMW prekininogen mRNAs by examination of cDNA clones for bovine HMW prekininogens and a genomic clone. Two types of cDNAs for HMW prekininogens have been identified. The deduced sequences of these two mRNAs are identical with those of two LMW prekininogen mRNAs up to the regions preceding the sequences specifying the divergent C-terminal regions of HMW and LMW kininogens, with one-to-one correspondence. In genomic DNA, the sequence precisely corresponding to the divergent 3'-terminal region of LMW prekininogen mRNA is located after 87 nucleotides downstream from the sequence specifying the 3'-untranslated region of HMW prekininogen mRNA. Based on these findings, we conclude that HMW and LMW prekininogen mRNAs are transcribed from the same gene.

A light microscopic study of the gastro-entero-pancreatic endocrine cells of the mink (Mustela vison)

Endocrine cells in the stomach, intestine and pancreas of the mink were investigated, using silver impregnation and immunohistochemical methods, and the following results were obtained. The stomach of the mink possesses a well-developed acid-secreting region which occupies about 70% of the gastric mucosa. Half of Brunner's glands whose excretory duct empties in the most proximal duodenum are located in the duodenal submucosa with the remainder in the pyloric submucosa. The area covered by the glands is 7.5 mm long in rostrocaudal direction. Endocrine cells are numerous in Brunner's glands, in the pyloric gland region and in the duodenum, while they are few in the colorectum. Somatostatin-immunoreactive cells are distributed throughout the whole GEP system, while gastrin-immunoreactive cells are located mainly in the pyloric gland region. Secretin-, motilin- and neurotensin-immunoreactive cells are found in the duodenum, jejunoileum and lower jejunoileum, respectively. Glucagon-immunoreactive cells are located mainly in the pancreatic islet and are distributed scarcely in the fundic gland region. A few glucagon-immunoreactive cells are also found in the middle portion of the jejunoileum. In addition to the somatostatin-immunoreactive cells, argentaffin, glucagon- and glicentin-immunoreactive cells in the fundic gland region and argentaffin and gastrin-immunoreactive cells in the pyloric gland region extend cytoplasmic processes along the basement membrane. This suggests a paracrine secretion of these cell types. A few open type cells which are stained with Hellerström-Hellman's or Sevier-Munger's method or are reactive to the somatostatin antiserum are found in the fundic gland region. A possible relation between the present observation of the endocrine cells and the eating habits of the mink is discussed.

The coupling valve graft: a procedure for double-valve replacement

Coupling valve grafting, a procedure to enlarge the annulus of the aortic valve and of the mitral valve simultaneously, is described. It consists of extending the J-shaped aortotomy through the middle of the noncoronary cusp into the superior aspect of the left atrium and down the anterior leaflet of the mitral valve. Then the mitral and aortic valves are replaced with a coupling valve graft, a vascular prosthesis attached to two prosthetic valves. This technique seems to be most suitable for patients in whom the valves of both annuli are narrow, as is often seen in aortic and mitral stenosis. Since both valve annuli can be enlarged greatly in this procedure, combinations of prosthetic valve sizes can be freely chosen for the two valves.

Small deletion in src of Rous sarcoma virus modifying transformation phenotypes: identification of 207-nucleotide deletion and its smaller product with protein kinase activity

Partial deletion in the src gene and the gene product were characterized in a deletion mutant, dl5, isolated from the Prague strain of Rous sarcoma virus. The mutant induced fusiform-like transformed cells, unlike the parental Prague strain, which induced round transformed cells. Determination of the total nucleotide sequences of src in dl5 and the Prague strain of Rous sarcoma virus demonstrated that in the former two deletions of 196 and 11 nucleotides had occurred at positions 403 and 696, respectively, from the 5' end of src. A protein with a molecular weight of 52,000 (p52src) was detected in cells infected with dl5, as predicted from the deletion size in src. From the nucleotide sequence, it was predicted that p52src had two deletions of 65 and 4 amino acids at positions 135 and 232, respectively, from the N-terminal methionine of p60src and also had 33 amino acid changes between these two deletion sites due to alteration of the reading frame. p52src, which contained deletions and alterations of amino acids near the N-terminus, showed protein kinase activity similar to that of p60src and functioned in the infected cells. These results strongly suggest that changes in the N-terminal region of p60src modified its transforming ability, causing induction of the fusiform-like transformation phenotype.

Molecular events leading to fusiform morphological transformation by partial src deletion mutant of Rous sarcoma virus

A mutant of the Prague strain of Rous sarcoma virus (RSV) has two deletions near the 5'-terminus of its src gene. The mutant (dl 5) induced fusiform morphological transformation in chick embryo fibroblasts (CEF) in contrast to the round type morphological transformation induced by wild type (wt) RSV. The partially deleted src of dl5 was shown to code for a 52K protein which has tyrosine kinase activity as high as that of p60src. In dl 5-transformed cells, a 36K protein was heavily phosphorylated, while two proteins (MW = 55K and 57K) were dephosphorylated to the same extent as compared with cells transformed by wt RSV. The relative abundance of phosphotyrosine in vinculin was almost the same in both dl 5- and wt RSV-transformed cells after extended passage of dl 5-transformed cells without marked changes in their morphology. On the other hand, the amounts of vinculin and fibronectin in dl 5-transformed cells were twice those in wt RSV-transformed cells, although less than the amounts in uninfected cells. These results suggest that events leading to cellular morphological transformation are neither directly correlated with phosphorylation of the 36K protein, with dephosphorylation of the 55K and 57K proteins, nor with the level of phosphorylation of tyrosine residues in vinculin, but rather are correlated with the amount of vinculin and fibronectin.

Angiotensinogen and kininogen: cloning and sequence analysis of the cDNAs

The primary structures of the angiotensinogen precursor and the low molecular weight (LMW) kininogen precursors have been deduced by determining the nucleotide sequences of cloned DNAs complementary to their mRNAs. The angiotensinogen precursor consists of a mature angiotensinogen of 453 amino acid residues and a putative signal peptide of 24 amino acid residues. An angiotensin moiety is located at the amino-terminal part of angiotensinogen, preceded directly by the signal peptide and followed by a large carboxyl-terminal sequence that contains two internally homologous sequences and three potential glycosylation sites. The LMW kininogen precursors are encoded by two very similar but distinct mRNAs and composed of 436 and 434 amino acid residues. Both kininogens contain two internally homologous sequences in which all amino acid differences between the two kininogens are located. This suggests that these homologous regions may be biologically significant in relation to the existence of two LMW kininogens.

Primary structures of bovine liver low molecular weight kininogen precursors and their two mRNAs

By using a mixture of synthetic oligodeoxyribonucleotides as a probe, cloned cDNA sequences specific for low molecular weight (LMW) kininogen have been isolated from a cDNA library of bovine liver mRNA sequences. Nucleotide sequence analyses of cloned cDNA inserts have revealed that bovine liver LMW kininogens are encoded by at least two very similar but distinct mRNAs. The corresponding amino acid sequences show that the LMW kininogen precursors of the two types, composed of 436 and 434 amino acid residues, both contain two internally homologous sequences in the amino-terminal portion between a signal peptide and a bradykinin moiety. The two mRNAs exhibit 15 nucleotide substitutions and 6 nucleotide deletions/additions in their protein-coding regions. The replacement of 13 amino acid residues and the deletions/additions of 2 amino acid residues in the two LMW kininogen precursors are all localized within the internally homologous regions, implying that these regions may be biologically significant in relation to the existence of two LMW kininogens. The nucleotide changes in the two mRNAs also occur in the limited portions that principally encode the internally homologous amino acid sequences. This suggests that the mRNAs are transcribed from the same gene to generate two LMW kininogen precursors differing only in the internally homologous sequences.

Vasoactive intestinal polypeptide (VIP) immunoreactivity of endocrine-like cells in the feline pyloric mucosa

Immunoreactivity to VIP by endocrine-like cells in the feline pyloric mucosa was examined by using three kinds of region-specific anti-porcine VIP sera. VIP-immunoreactive endocrine-like cells were detected clearly with all of the VIP antisera used. They were located mainly around the neck of the pyloric glands. Some of these endocrine-like cells showed dilution-dependent immunoreactivity against VIP antisera. The immunostaining intensity of VIP-immunoreactive endocrine-like cells showing dilution-independence could not be distinguished from those of nerve elements. The present results suggest that the immunoreactivity with properties very similar to those of authentic VIP may be present in the endocrine-like cells of the feline pyloric glands.

Avian sarcoma virus Y73 genome sequence and structural similarity of its transforming gene product to that of Rous sarcoma virus

From the complete nucleotide sequence of the genome of the avian sarcoma virus Y73, we have predicted amino acid sequence of p90 gag-yes, the product of the transforming gene. Contrary to previous evidence from molecular hybridization studies p90 gag-yes was found to have much homology with the transforming gene product p60 src of Rous sarcoma virus, suggesting that the cellular counterparts of the two (c-yes and c-src) originated from a common prototype sequence.

Molecular cloning of the genome of poliovirus type 1

Poliovirus cDNA.RNA hybrids were prepared from the Mahoney strain of poliovirus type 1 by using reverse transcriptase (RNA-dependent DNA nucleotidyltransferase) and cloned in the Escherichia coli plasmid pBR322. Bacteria colonies carrying recombinant plasmids were selected by in situ hybridization with virus-specific RNase T1-resistant oligonucleotides. Analysis of the cDNA inserts by restriction mapping and electron microscopy showed that the cloned cDNAs, the longest of which was 3.2 kilobase pairs, originated from various parts of the viral RNA, covering at least 99% of the genome length. Due to overlapping of the clones, the restriction map of the poliovirus genome could be reconstructed. The complete 5' end of the genome was successfully cloned in at least one of the recombinant plasmids, pPV1-366.

Primary structure, gene organization and polypeptide expression of poliovirus RNA

The primary structure of the poliovirus genome has been determined. The RNA molecule is 7,433 nucleotides long, polyadenylated at the 3' terminus, and covalently linked to a small protein (VPg) at the 5' terminus. An open reading frame of 2,207 consecutive triplets spans over 89% of the nucleotide sequence and codes for the viral polyprotein NCVPOO. Twelve viral polypeptides have been mapped by amino acid sequence analysis and were found to be proteolytic cleavage products of the polyprotein, cleavages occurring predominantly at Gln-Gly pairs.

Poliovirus replication proteins: RNA sequence encoding P3-1b and the sites of proteolytic processing

A partial amino-terminal amino acid sequence of each of the major proteins encoded by the replicase region (P3) of the poliovirus genome has been determined. A comparison of this sequence information with the amino acid sequence predicted from the RNA sequence that has been determined for the 3' region of the poliovirus genome has allowed us to locate precisely the proteolytic cleavage sites at which the initial polyprotein is processed to create the poliovirus products P3-1b (NCVP1b), P3-2 (NCVP2), P3-4b (NCVP4b), and P3-7c (NCVP7c). For each of these products, as well as for the small genome-linked protein VPg, proteolytic cleavage occurs between a glutamine and a glycine residue to create the amino terminus of each protein. This result suggests that a single proteinase may be responsible for all of these cleavages. The sequence data also allow the precise positioning of the genome-linked protein VPg within the precursor P3-1b just proximal to the amino terminus of polypeptide P3-2.

The genome-linked protein of picornaviruses. VII. Genetic mapping of poliovirus VPg by protein and RNA sequence studies

The poliovirus genome-linked protein (VPg) has been subjected to radiochemical microsequence analysis. Sequence studies of virion RNA by a modification of Sanger's dideoxy method have revealed a base sequence corresponding to the amino acid analysis. This result proves that VPg is virus-encoded. The RNA sequence has allowed us to predict the total amino acid sequence of VPg and part of its precursor. VPg is, at most, 27 amino acids long. It maps within the 3' terminal segment of the viral genome that encodes the precursor polypeptide NCVP1b for the virus-specific RNA polymerase NCVP4.

Sequence of 1060 3'-terminal nucleotides of poliovirus RNA as determined by a modification of the dideoxynucleotide method

The dideoxynucleotide method for sequencing DNA developed by Sanger et al. [Sanger, F., Nicklen, S. & Coulson, A. (1977) Proc. Natl. Acad. Sci. USA 74, 5463-5467] was modified to allow sequence analysis of poliovirus RNA without recourse to cloning. Our method involves reverse transcription of poliovirus RNA followed by cDNA-dependent DNA synthesis in the presence of unlabeled dNTPs and 2',3'-dideoxynucleoside triphosphates, with Escherichia coli DNA polymerase I (Klenow) used to catalyze the reaction. DNA synthesis is primed by 5'-32P-labeled RNase T1- or RNase A-resistant oligonucleotides generated from poliovirus RNA. The sequence of 1060 nucleotides preceding the 3'-terminal poly(A) is presented. Based on the position of termination codons we propose that viral translation terminates at nucleotide -562.

Long-term follow-up of artificial valves in patients under 15 years old

Forty-nine artificial cardiac valves implanted in 44 patients less than 15 years old were reviewed. Out of 49 valves, 16 were mechanical and 33 were xenografts. Average follow-up was 2 years 5 months. Marked valvular stenosis developed in 11 out of the 33 xenografts, an incidence of 15% per patient-year. In patients with a xenograft valve, the incidence of sepsis was found to be 4% per patient-year and brain accidents, 4% per patient-year. In patients with mechanical valves, the incidence of stenosis was only 2% per patient-year and brain accidents, 2% per patient-year. There was no sepsis. From these follow-up results, mechanical valves seem to be superior to xenografts when used in patients less than 15 years old.

Sequence studies of poliovirus RNA. IV. Nucleotide sequence complexities of poliovirus type 1, type 2 and two type 1 defective interfering particles RNAs, and fingerprint of the poliovirus type 3 genome

The 32P-labelled genomes of poliovirus type 1, 2 and 3 have been digested with RNase T1 and the products separated by two-dimensional gel electrophoresis. All three fingerprints differ in the separation pattern of the large oligonucleotides. The molar yields of the large RNase T1-resistant oligonucleotides of type 1 and type 2 RNA of poliovirus RNA are close to one. By comparing the yields of these oligonucleotides to the amount of RNA from which they originated, the chain length of type 1 poliovirus RNA was found to be 7851 +/- 567 nucleotides (mol. wt. 2.66 +/- 0.19 x 10(6) and that of poliovirus type 2, 8181 +/- 578 nucleotides (mol. wt. 2.77 +/- 0.19 x 10(6). The chain length of two defective interfering particle (DI) RNAs of poliovirus type 1 were determined to be 7042 +/- 999 nucleotides for DI(1) and 6639 +/- 674 nucleotides for DI(2).

The 5'-terminal structures of poliovirion RNA and poliovirus mRNA differ only in the genome-linked protein VPg

The 5'-terminal, RNase T1-resistant oligonucleotide of poliovirus mRNA has been isolated. Its sequence is pU-U-A-A-A-A-C-A-Gp, which is identical to that of virion RNA except that the genome-linked protein VPg is absent [Nomoto, A., Detjen, B., Pozzatti, R. & Wimmer, E. (1977) Nature 268, 208-213]. Because all newly synthesized viral RNAs are VPg-linked, we propose that VPg is cleaved from progeny RNA at the linkage between protein and nucleic acid prior to polyribosome formation. This may represent a new mode of processing of viral macromolecules. Virion RNA from which VPg has been cleaved proteolytically retains its specific infectivity, an observation suggesting that VPg is not involved in early steps (penetration and translation) of the infectious cycle initiated by RNA.