Rational design, discovery, and synthesis of a novel series of potent growth hormone secretagogues

In the joint experimental and computational efforts reported here to obtain novel chemical entities as growth hormone secretagogues (GHSs), a small database of peptides and non-peptides known to have GHS activity was used to generate and assess a 3D pharmacophore for this activity. This pharmacophore was obtained using a systematic and efficient procedure, "DistComp", developed in our laboratory. The 3D pharmacophore identified was then used to search 3D databases to explore chemical structures that could be novel GHSs. A number of these were chosen for synthesis and assessment of their ability to release growth hormone (GH) from rat pituitary cells. Among the compounds tested, those with a benzothiazepin scaffold were discovered with micromolar activity. To facilitate lead optimization, a second program, a site-dependent fragment QSAR procedure was developed. This program calculates a library of chemical and physical properties of "fragments" or chemical components in a known pharmacophore and determines which, if any, of these properties are important for the observed activity. The combined use of the 3D pharmacophore and the results of the site-dependent fragment QSAR analysis led to the discovery and synthesis of a novel series of potent GHSs, a number of which had nanomolar in vitro activity.

Structure of the human type XIX collagen (COL19A1) gene, which suggests it has arisen from an ancestor gene of the FACIT family

Type XIX collagen is a newly discovered member of the FACIT (fibril-associated collagens with interrupted triple helices) group of extracellular matrix proteins. Based on the primary structure, type XIX collagen is thought to act as a cross-bridge between fibrils and other extracellular matrix molecules. Here we describe the complete exon/intron organization of COL19A1 and show that it contains 51 exons, spanning more than 250 kb of genomic DNA. The comparison of exon structures of COL19A1 and other FACIT family genes revealed several similarities among these genes. The structure of exons encoding the noncollagenous (NC) 1-collagenous (COL) 1-NC 2-COL 2-NC 3-COL 3-NC 4 domain of the alpha1(XIX) chain is similar to that of the NC 1-COL 1-NC 2-COL 3-NC 3 domain of the alpha2(IX) chain except for the NC 3 domain of alpha1(XIX). The exons encoding the COL 5-NC 6 domain of alpha1(XIX) are also similar to those of the COL 3-NC 4 domain of alpha1(IX) chain. Previously, COL19A1 was mapped to human chromosome 6q12-q14, where COL9A1 is also located. Likewise, the present work shows that the mouse Col19a1 gene is located on mouse chromosome 1, region A3, where Col9a1 has also been mapped. Taken together, the data suggest that COL19A1 and COL9A1 (Col19a1 and Col9a1) were duplicated from the same ancestor gene of the FACIT family. Three CA repeat markers with high heterozygosity were found in COL19A1. These markers may be useful for linkage analysis of age-related inheritable diseases involved in eyes and/or brain.

Ubiquitous expression of the alpha1(XIX) collagen gene (Col19a1) during mouse embryogenesis becomes restricted to a few tissues in the adult organism

Type XIX collagen is a poorly characterized member of the fibril-associated collagens with an interrupted triple helices (FACIT) class of collagen molecules. As a first step toward elucidating its function, we have isolated full size cDNA clones from the mouse alpha1(XIX) collagen gene (Col19a1) and established its pattern of expression in the developing embryo and adult organism. Col19a1 transcripts can be detected as early as 11 days of gestation and in all embryonic tissues, except the liver, of an 18-day postcoitum mouse. In contrast, only a few adult tissues, brain, eye, and testis, seem to accumulate Col19a1 mRNA. Col19a1 transcripts are at least 10 times more abundant in adult than fetal brain and significantly less in adult than fetal muscle and skin. Consistent with the RNA data, polyclonal antibodies for alpha1(XIX) collagen reacted with a 150-kDa protein in the neutral salt extraction of adult mouse brain tissues. We therefore propose that type XIX collagen plays a distinct role from the other FACIT molecules, particularly in the assembly of embryonic matrices and in the maintenance of specific adult tissues.

Developmental pattern of expression of the mouse alpha 1 (XI) collagen gene (Col11a1)

Fibrillar networks are intimately involved in several morphogenetic processes which underlie the harmonious development of the vertebrate embryo. Recent genetic evidence has demonstrated that the minor types V and XI collagen are key regulators of types I and II fibrillogenesis in non-cartilaginous and cartilaginous matrices, respectively. A comprehensive understanding of the expression and regulation of the genes coding for the chains of the minor collagen types is therefore relevant to animal morphogenesis and development. The present study was undertaken to elucidate the embryonic pattern of expression of the gene coding for the mouse alpha 1 chain of type XI colagen (Col11a1) using the technique of in situ hybridization. Transcripts of the Col11a1 gene were detected as early as 11 days of gestation. The alpha 1(XI) transcripts were found to accumulate mostly in cartilaginous tissues, such as the chondrocranium and the developing limbs. Like the major cartilage-specific collagen (type II), Col11a1 expression was also noted in the neuro-epithelium of the brain. However, alpha 1(XI) transcripts accumulated in several other non-cartilaginous sites. They include odontoblasts, trabecular bones, atrioventricular valve of the heart, the tongue, the intestine, and the otic vesicle. Altogether, the data confirm that Col11a1 has a broader spectrum of expression than previously thought. This finding raises the possibility that the alpha 1(XI) chain may participate in the formation of stage- and tissue-specific trimers with distinct functional properties.

Coding sequence and alternative splicing of the mouse alpha 1(XI) collagen gene (Col11a1)

Several overlapping cDNA clones corresponding to the entire coding sequence of the mouse alpha 1(XI) collagen gene (Col11 a1) were isolated. The conceptual amino acid translation indicated a high degree of sequence identity (93%) with the human alpha 1(XI) chain. The cloning experiments also revealed alternative splicing of the sequence coding for 85 residues located within the acidic region of the amino-globular domain of alpha 1(XI). Analysis of RNA samples from different embryonic tissues suggested that alternative splicing might be confined to tissue destined to become bone.

Structural and functional analysis of the promoter of the human alpha 1(XI) collagen gene

In order to eventually elucidate the mechanisms regulating alpha 1(XI) collagen expression in cartilaginous and non-cartilaginous tissues, we performed an initial analysis of the structural-functional features of the promoter of the human gene (COL11A1). After cloning and sequencing the 5' portion of COL11A1, primer extension and nuclease protection assays identified several minor transcriptional start sites clustered around a major one located 318 base pairs from the ATG codon. Consistent with this finding, analysis of the upstream sequence revealed the absence of a TATA motif and the presence of several GC boxes. Transient transfection experiments delineated the smallest promoter sequence directing relatively high expression of a reporter gene in a cell type-specific manner. Nine nuclear protein-bound areas were located within this promoter sequence of the COL11A1 gene. Sequence homologies suggested that the majority of the footprints correspond to potential binding sites for ubiquitous nuclear proteins, such as AP2 and Sp1. Additional experimental evidence indicated that one of the protected areas may bind a transcriptional complex that is identical or closely related to the one that regulates tissue specificity in the coordinately expressed alpha 2(V) collagen gene.

The mRNA for alpha 1(XIX) collagen chain, a new member of FACITs, contains a long unusual 3' untranslated region and displays many unique splicing variants

We have isolated cDNAs and completed for the first time the primary structure for a novel collagenous chain that was partially characterized earlier and named alpha 1(Y) chain [Yoshioka, H. et al. (1992) Genomics 13, 884-886]. The size of the coding region was unexpectedly small compared with the length of the mRNA (> 10 kb), owing to the presence of a long 3' untranslated region (> 5 kb). The predicted polypeptide contained 1,142 amino acid residues with a 23-residue signal peptide consisting of 5 collagenous domains of 70-224 residues in length, interspersed and flanked with 6 noncollagenous (NC) domains. The primary structure is distinct from those of the 32 known collagen alpha-chains of types I through XVIII. Therefore, we designate this newly discovered collagen chain the alpha 1 chain of type XIX collagen. Sequence analysis suggested that this chain belongs to the recently discovered group of collagens known as FACITs (fibril associated collagens with interrupted triple-helices). Northern blotting analysis demonstrated hybridization of the cDNA to a large mRNA species (> 10 kb) extracted from a rhabdomyosarcoma cell line (CCL 136). We also isolated numerous truncated cDNA clones of which the 3' parts were different from the "proto" type of the mRNA of > 10-kb size. Sequence comparison between cDNAs and corresponding genomic DNA fragments indicated that unusual splicing events occurred through insufficient recognition at acceptor sites. Expression of the gene was extremely infrequent in the rhabdomyosarcoma cell line; it could be restricted to certain animal tissues both temporally and spatially during early development.

Assessment of lymph node metastasis and vessel invasion in early rectal cancer

Thirteen patients with rectal carcinoma seen between December 1980 and December 1990 have been reviewed to determine the risk of lymph node metastasis and its implication for subsequent treatment. The mean age was 64 years (from 38 to 79; 9 males, 4 females). The site of the tumor was predominantly in the lower rectum (53.8 percent). The polypoid (I) and flat-elevated ulcerated (IIa + IIc) subtypes were detected in seven and six lesions, respectively. Sphincter-saving techniques were carried out in eight cases, and five cases required Miles' operation. Neither postoperative complications nor deaths were noted. The mean follow-up period was 57 months (6 to 133 months). No recurrence or distant metastasis was found during this follow-up. IIa + IIc subtype lesions with deep submucosal invasion at or beyond Smlc level were closely related with lymphatic and vascular invasion. Although this association was not necessarily accompanied by an increased number of involved lymph nodes, major surgical resection is suggested in such IIa + IIc cases due to an increased possibility for lymph node metastasis.

Phase I study of recombinant human tumor necrosis factor

A phase I clinical and pharmacokinetic study of recombinant human tumor necrosis factor (rH-TNF) was conducted in a single dose schedule in 33 patients with advanced cancer. rH-TNF was given by i.v. infusion over 30 min with a starting dose of 1 x 10(5) units/m2. The dose was escalated up to 16 x 10(5) units/m2 according to the modified Fibonacci scheme. Toxic effects were similar but not identical to those reported with interferons and interleukin-2, and included fever, rigors, nausea and vomiting and anorexia in a non-dose-dependent manner, and hypotension, leukocytosis, thrombocytopenia and transient elevation of transaminases (SGOT and SGPT) in an approximately dose-dependent manner. DIC syndrome was observed in one patient who had received 16 x 10(5) units/m2. The dose-limiting toxicities were hypotension, thrombocytopenia and hepatotoxicity, and the maximum tolerated dose in a single i.v. infusion of rH-TNF appeared to be 12 x 10(5) units/m2 when thrombocytopenia and elevation of SGOT and SGPT were taken as the dose-limiting toxicities. However, if hypotension was included, the maximum safely tolerated dose appeared to be 5 x 10(5) units/m2.

Reduction of lipogenic enzymes by shellfish triglycerides in rat liver

When rats were fed for 2 weeks on 3% fat diets containing 0.5 or 1%corbicula (Corbicula japonica PRIME), clam (Tapes japonica) or oyster (Callocorchina) triglycerides, serum and liver triglyceride levels were significantly lowered. The activities of hepatic glucose-6-phosphate dehydrogenase, malic enzyme and acetyl-CoA carboxylase were markedly reduced in the rats. Cholesterol synthesis by liver slices was also reduced. The results of immunochemical titrations and Ouchterlony double-diffusion analysis indicated that the decreases in the activities of acetyl-CoA carboxylase and glucose-6-phosphate dehydrogenase were due to decreases in the enzyme quantities. The shellfish triglycerides include a high percentage of long chain and polyunsaturated fatty acids, which are common to and characteristic of the three kinds of shellfish. They would be effective components in these observations.

Identification of shellfish fatty acids and their effects on lipogenic enzymes

The fatty acids which are common to and characteristic of shellfish, were identified by mass spectrometry and NMR spectral analyses as being: octadecatetraenoioc acid, eicosapentaenoic acid, docosapentaenoic acid and docosahexaenoic acid. When the fatty acids isolated by high performance liquid chromatography were separately intubated into rats, hepatic glucose-6-phosphate dehydrogenase (EC 1.1.1.49), malic enzyme (EC 1.1.1.40) and acetyl-CoA carboxylase (EC 6.4.1.2) were reduced more effectively as compared with linoleic acid intubation. These enzymes were reduced most markedly by eicosapentaenoic acid-intubation. The fatty acids seem to be effective components in reduction of triacylglycerol and lipogenic enzyme levels in rats fed on shellfish.

A possible role of Z protein in dietary control of hepatic triacylglycerol synthesis

The effects of fasting and refeeding on hepatic Z protein were investigated in rats. When [U-14C]palmityl-CoA was added to the liver cytosol fraction from fat-free refed rats, more binding of labeled palmityl-CoA to the Z-protein region was found than in the case of fasted rats. Also the radioactivities in specific precipitations of the palmityl-CoA binding protein with anti-Z immunoglobulin G were higher in the refed rats. The Z protein which stimulated diacylglycerol acyltransferase may be involved in the change of triacylglycerol synthesis in fasted and refed rat livers.

Effect of feeding the shell fish (Corbicula japonica) on lipid metabolism in the rat

Rats were maintained for 2 weeks on 3 different diets; a basal diet, one containing 0.1% cholate, and one containing 0.1% cholesterol and 0.1% cholate. Each dietary group was further divided into subgroups whose diet contained 0, 5 or 10% (dry weight) of minced corbicula (Corbicula japonica Prime). Feeding corbicula significantly reduced the increase of cholesterol levels in rats fed the cholesterol diet. Though corbicula contains several sterols, sterols other than cholesterol were almost not absorbed. Serum and liver triglyceride levels were significantly reduced by feeding corbicula meat in all the dietary groups. Activities of glucose-6-phosphate dehydrogenase, malic enzyme and acetyl-CoA carboxylase were also markedly reduced by feeding corbicula. The results suggest that corbicula is a hypolipidemic food.

Influences of oyster or clam feeding on lipid metabolism in rats

Rats were fed on three kinds of diets for two weeks: (I) basal diet, (II) containing 0.1% cholate and (III) containing 0.1% cholesterol and 0.1% cholate. Each dietary group was further divided into subgroups to whose diet was added 0, 5 or 10% (dry weight) of minced oyster (Callocorchina) or clam (Tapes japonica). The serum and liver cholesterol levels of the rats fed the basal diet were reduced by feeding oyster or clam. The serum and liver triglyceride levels of all dietary groups were lowered markedly by feeding oyster or clam. The activities of glucose-6-phosphate dehydrogenase, malic enzyme and acetyl-CoA carboxylase were markedly reduced in the basal groups fed oyster or clam. These effects were observed in 5 and 10% shellfish feeding. These shellfish may be considered hypolipidemic foods.