Biomedical subjects

H W Jansen

Publications and source records attributed to H W Jansen.

At least 55 records · Page 3Linked to original sources

PubMed1985

Cyclic nucleotides and growth regulation of the mandibular condylar cartilage of the rat in vitro.

By exogenous interference in the intracellular level of cAMP and cGMP during growth in vitro without and with compression, an indication was obtained for the mediatorial involvement of these cyclic nucleotides in the major growth-processes in the mandibular condylar cartilage of 4-day-old rats. Raising the intracellular level of cAMP reduced proliferative activity in the prechondroblast zone, did not affect matrix synthesis by the functional chondroblasts and stimulated the process of hypertrophy. Intracellular elevation of cGMP had an antagonistic effect; it stimulated proliferation as well as matrix synthesis, but had no effect on hypertrophy. In this specific type of cartilage, cGMP can be considered as a major secondary intracellular messenger for proliferation-stimulating continuous biomechanical stimuli.

Animals↗

PubMed1985

Nucleotide sequence analysis of the chicken gene c-mil, the progenitor of the retroviral oncogene v-mil.

The nucleotide sequence of the chicken gene c-mil was determined within and around all regions homologous to the oncogene v-mil of avian retrovirus MH2. The regions of homology to the previously determined v-mil sequence, ranging in size from 28 to 177 base pairs (bp), are distributed over 14 kilobase pairs (kbp) of the chicken genome and are organized in 11 exons. All exon-intron boundaries of c-mil, except the 5' boundary of exon 1 and the 3' boundary of exon 11, were unambiguously defined by the identification of consensus splice donor and acceptor sites precisely at positions where homology to v-mil ceases or resumes. The homology to v-mil starts within the coding sequence of exon 1 and ends within the 3' untranslated region of exon 11, 12 nucleotides downstream from the nonsense codon terminating the large open reading frame shared between c-mil and v-mil. The c-mil and v-mil sequences differ at only 7 out of 1153 nucleotide positions, and the predicted sequences of v-mil and c-mil proteins differ by one conservative and four nonconservative substitutions among 379 amino acid residues. Hence, the carboxy-terminal domains of the MH2 gag-mil hybrid protein and of the putative c-mil protein are very similar. However, the amino-terminal domain of the cellular protein is possibly encoded by additional 5' c-mil sequences not present in the transduced v-mil oncogene, while that of the MH2 hybrid protein is encoded by viral gag sequences. The sequence analysis also revealed that c-mil and c-myc derived sequences are immediately adjacent on the MH2 genome carrying both the v-mil and the v-myc oncogene. Hence, transduction of c-mil into MH2 involved recombination, at the 3' site, with either the c-myc locus or a previously transduced v-myc gene, and, at the 5' site, with gag sequences of the transducing virus. At both sites, no significant homologies were found between the sequence elements involved in the recombination.

Amino Acid Sequence↗

PubMed1985

Molecular cloning of proviral DNA and structural analysis of the transduced myc oncogene of avian oncovirus CMII.

Molecularly cloned proviral DNA of avian oncogenic retrovirus CMII was isolated by screening a genomic library of a CMII-transformed quail cell line with a myc-specific probe. On a 10.4-kilobase EcoRI fragment, the cloned DNA contained 4.4 kilobases of CMII proviral sequences extending from the 5' long terminal repeat to the EcoRI site within the partial (delta) complement of the env gene. The gene order of CMII proviral DNA is 5'-delta gag-v-myc-delta pol-delta env-3'. All three structural genes are partially deleted: the gag gene at the 3' end, the env gene at the 5' end, and the pol gene at both ends. The delta gag (0.83 kilobases)-v-myc (1.50 kilobases) sequences encode the p90gag-myc transforming protein of CMII. In comparison with the p110gag-myc protein of acute leukemia virus MC29, p90gag-myc lacks amino acids corresponding to additional 516 bases of gag sequences and 12 bases of 5' v-myc sequences present in the MC29 genome. Nucleotide sequence analysis of CMII proviral DNA at the delta gag-v-myc and the v-myc-delta pol junctions revealed significant homologies between avian retroviral structural genes and the cellular oncogene c-myc precisely at the positions corresponding to the gene junctions in CMII. Furthermore, the delta gag-v-myc junction in CMII corresponds to sequence elements in gag and C-myc that are possible splicing signals. The data suggest that transduction of cellular oncogenes may involve RNA splicing and recombination with homologous sequences on retroviral vectors. Different sequence elements of both the retroviral vectors and the c-myc gene recombined during genesis of highly oncogenic retroviruses CMII, MC29, or MH2.

Animals↗

PubMed1985

Rapid induction of hemopoietic neoplasms in newborn mice by a raf(mil)/myc recombinant murine retrovirus.

3611 MSV, a raf oncogene-transducing murine retrovirus, induced fibrosarcomas in newborn mice after a latency of 4 to 8 weeks. In contrast, newly constructed recombinant murine retroviruses carrying the myc oncogene did not induce tumors before greater than or equal to 9 weeks. A combination of both oncogenes in an infectious murine retrovirus induced hematopoietic neoplasms in addition to less prominent fibrosarcomas and pancreatic acinar dysplasia 1 to 3 weeks after inoculation. The hematological neoplasms consisted of immunoblastic lymphomas of T- and B-lineage cells and erythroblastosis. Cell lines from these tumors could be readily established in culture in regular medium, whereas culture of cells from raf oncogene-induced tumors required the addition of interleukin 3. In parallel to the synergistic action of both oncogenes on hematopoietic cells in vivo, we found that raf oncogene-induced transformation of fibroblast cell lines in culture was enhanced by the addition of myc, which by itself did not morphologically transform these permanent cell lines. We conclude that concomitant expression of raf and myc oncogenes in hematopoietic cells and fibroblastic cell lines enhances their respective transforming activities.

Animals↗

PubMed1985

Effect of compressive forces on phosphatase activity in mandibular condylar cartilage of the rat in vitro.

Intermittent and continuous compressive forces were applied to mandibular condylar cartilages from four days old rats during culture. The distribution and the relative activity of alkaline and acid phosphatase were determined after various periods in culture. The application of a continuous compressive force reduced the activity evenly of both phosphatases in all zones of the condylar cartilage. A small intermittent compressive force (0.5-1.0 g) induced an increase in the intra- and extracellular alkaline phosphatase activity in the entire hypertrophic zone. It is concluded that biomechanical forces can influence the onset of the mineralisation process in mandibular condylar cartilage.

Acid Phosphatase↗

PubMed1984

The gapped duplex DNA approach to oligonucleotide-directed mutation construction.

A simple and efficient method is described to introduce structurally pre-determined mutations into recombinant genomes of filamentous phage M13. The method rests on gapped duplex DNA (gdDNA) molecules of the phage M13 genome as the key intermediate. In this gdDNA, the (+) and the (shorter) (-) strand carry different genetic markers in such a way, that a rigorous selection can be applied for phage carrying the markers of the (-) strand. For introduction of the mutation, a synthetic oligonucleotide with partial homology to a target site within the single stranded DNA region is annealed to the gdDNA. The oligonucleotide subsequently becomes part of the (-) strand by enzymatic DNA gap filling and sealing. This physical linkage is preserved at the genetic level after transfection of a recipient E.coli strain deficient in DNA mismatch correction, so that the synthetic marker can be selected from the phage progeny independent from its potential phenotype. It is demonstrated that by this method mutants can be constructed with marker yields in excess of 70%.

Coliphages↗

PubMed1984

Muscle fibre types and muscle spindles in the jaw musculature of the rat.

The fibre composition and occurrence of muscle spindles was studied in the masticatory, the suprahyoid and the infrahyoid muscles of the rat. Muscle fibres were typed as fast-white, fast-intermediate, fast-red and slow-red according to their ATPase and SDH activity. Fibre type appeared to be closely related to fibre diameter. In most of the muscles, all four fibre types were found. Slow-red fibres were absent in the superficial masseter, the transverse mandibular and the omohyoid muscles; fast-white fibres were absent in the mylohyoid muscle. The masticatory muscles were mainly composed of the three fast-fibre types; the jaw-opener muscles (the anterior digastric, the posterior digastric, the posterior digastric, the stylohyoid and the lateral pterygoid muscle) showed more slow-red fibres. In the masticatory and most of the suprahyoid muscles, the slow-red fibres were restricted to an area with high SDH activity. In the infrahyoid muscles, the fibre types were evenly distributed. Many muscle spindles, often clustered, were found in the masticatory muscles, except in the lateral pterygoid. In most of the suprahyoid muscles, these sensory structures were absent. In the infrahyoid muscles, solitary muscle spindles were found.

Adenosine Triphosphatases↗

PubMed1984

Merkel cell-neurite complexes in the hard palate of the Wistar rat (Rattus norvegicus).

The complexes were found in the basal layer of the epithelium of the rugae of the ante- and intermolar area of the palate. Asymmetric membrane densities were observed between the Merkel cell and its neurite or the adjacent keratinocytes. The cytoplasm of the Merkel cell was characterized by an accumulation of membrane-bound dense granules at the neurite side of the cell and by a well developed Golgi apparatus at its keratinocyte side.

Animals↗

PubMed1984

Structural relationship between the chicken protooncogene c-mil and the retroviral oncogene v-mil.

The avian leukemia and carcinoma inducing retrovirus MH2 contains the novel oncogene v-mil in addition to the cell-derived oncogene v-myc. High-molecular-weight chicken DNA contains sequences closely related to v-mil and also sequences more distantly related to this gene. Several phage clones were isolated by screening of a chicken recombinant DNA library with a v-mil-specific probe in stringent conditions. These clones contain overlapping segments of v-mil-related chicken DNA. Hence, the sequences closely related to v-mil, termed c-mil, appear to represent a single-copy locus of the chicken genome. The close relationship between the cellular and the viral gene was demonstrated by hybridization between c-mil DNA and MH2 viral RNA, or between c-mil DNA and cloned v-mil DNA, and by a comparison of their restriction maps, which revealed total conservation in c-mil DNA of all restriction sites found in v-mil DNA. The c-mil locus spans at least 10 kb, with nine regions of homology to v-mil, ranging in size from about 0.07 to 0.17 kb, interrupted by eight intervening sequences with complexities of about 0.5 to 3.5 kb. Analyses of the cloned chicken c-mil and c-myc loci by nucleic acid hybridization employing specific probes from the mil-myc junction of MH2 proviral DNA revealed that c-mil- and c-myc-related sequences are directly adjacent in the viral genome and that MH2 contains additional 5' c-myc-related sequences not present in the genomes of other leukemia viruses carrying the v-myc oncogene.

Animals↗

PubMed1984

3'-Terminal region of avian carcinoma virus MH2 shares sequence elements with avian sarcoma viruses Y73 and SR-A.

We determined the nucleotide sequence of the acute transforming avian retrovirus MH2 from an HgiAI site within the coding region of its oncogene, v-myc, to the KpnI site within the long terminal repeat. Comparison with published sequences from other retroviruses allowed us to identify all sequence elements in this region. We conclude that MH2 contains a unique assembly of 3'-terminal sequences, which includes part of the helper virus-derived SPC region of avian sarcoma virus Y73 and the complete F3 and F1 segments of Rous sarcoma virus strain SR-A.

Animals↗

PubMed1984

The use of chromic potassium sulphate in bone electron microscopy.

The ultrastructure of endochondral bone was studied using an aqueous solution of chromic potassium sulphate as the decalcifying agent. 0.5 mm thick sections of rat tibiae were fixed in buffered glutaraldehyde, immersed in an aqueous solution of 1% chromic potassium sulphate pH 3.4, dehydrated and embedded in Poly Bed 812 without exposure to osmium tetroxide. In unstained sections we observed clusters of crystal like structures throughout the osteoid and calcifying cartilage matrix as well as solitary needle shaped structures in association with collagen fibrils. Stained sections revealed nuclei, endoplasmic reticulum, membrane limited dense granules, mitochondrial particles and other cell components typical of bone cells. It appeared that the chromic potassium sulphate method preserves the relationship between hard and soft tissues well, gives fine cytological detail and produces images of intracellular and extracellular deposits identical to untreated crystallites. It is concluded that the chromic potassium sulphate method is indicated for ultrastructural studies of bone.

Animals↗

PubMed1984

An histological investigation of invaginated human incisors.

The outlines of the invaginations resembled bottles with narrow necks directed at the incisal edge of the teeth. It is proposed that this form is genetically predetermined and that an active or passive infolding gives rise to the invaginations. In one case investigated out of six, an interruption of the dentin layer, surrounding the invagination, was found. This could become a susceptible site for post-eruptive bacterial invasion. In all cases, considerable amounts of enamel with normal structure were found in the invagination. The centrally positioned connective tissue was richly supplied with blood vessels and lined with layers of epithelial tissue, demonstrating various stages of an involutive enamel organ.

Dens in Dente↗

PubMed1983

Two unrelated cell-derived sequences in the genome of avian leukemia and carcinoma inducing retrovirus MH2.

Molecularly cloned proviral DNA of avian replication-defective retrovirus Mill Hill No. 2 (MH2) was analyzed. The MH2 provirus measures 5.5 kb including two long terminal repeats (LTR), and contains a partial complement of the structural gene gag, 1.5 kb in size, near the 5' terminus, and a 1.3-kb segment of the v-myc transforming gene near the 3' terminus. These v-myc sequences are closely related to the v-myc transforming gene of avian acute leukemia virus MC29, and to the cellular chicken gene c-myc. The gag and myc domains on the MH2 provirus are separated by unique sequences, 1.3 kb in size and termed v-mil, which are unrelated to v-myc, or to other oncogenes or structural genes of the avian leukemia-sarcoma group of retroviruses. Normal chicken DNA contains sequences closely related to v-mil, termed c-mil. Analyses of chicken c-mil clones isolated from a recombinant DNA library of the chicken genome reveal that c-mil is a single genetic locus with a complex split gene structure. In the MH2 genome, v-mil is expressed via genome-sized mRNA as a gag-related hybrid protein, p100gag-mil, while v-myc is apparently expressed via subgenomic mRNA independently from major coding regions of structural genes. The presence in the MH2 genome of two unrelated cell-derived sequences and their independent expression may be significant for the oncogenic specificities of this virus.

Animals↗

PubMed1983

Isolation and characterization of snRNA and scRNA gene candidates from a human genomic library.

A simple procedure for the isolation and preparative gel electrophoresis of snRNA and scRNA is described. These small RNA species were used to select DNA sequences from a human genomic library which are able to protect hybridized snRNA or scRNA against T1-ribonuclease attack. The snRNA clones obtained contain only sequences for one snRNA species and only one copy of the respective gene. In contrast, more than one 7S RNA gene is present within the scRNA clones.

Cloning, Molecular↗

PubMed1983

Growth of the mandibular condylar cartilage of the rat in serum-free organ culture.

To evaluate the intrinsic capacity for growth, the mandibular condylar cartilage of 4-day-old rats was cultured in a serum-free, chemically-defined medium for 28 days and compared with the condylar cartilage cultured in a serum-supplemented medium and with the normal growth in vivo. Under the serum-free culture conditions, cell proliferation, differentiation into functional chondroblasts and matrix formation continued, but chondroclasia and osteogenesis were absent. This resulted, after 28 days of culture, in an enlarged condylar cartilage with altered proportions, a severe reduction of the prechondroblastic and the transitional zone and a considerable increase of the hypertrophic zone. It appears that the serum-free culture system is unfavourable for endochondral osteogenesis and lacks factors modulating the rate of proliferation, differentiation and maturation of the prechondroblasts. In the functional environment of the condyle, humoral or mechanical factors seem to exert this essential modulating influence on the condylar-cartilage growth.

Animals↗

PubMed1983

Genome structure of HBI, a variant of acute leukemia virus MC29 with unique oncogenic properties.

We have analyzed the viral RNA of a variant of avian acute leukemia virus MC29, termed HBI. This virus was isolated during in vitro passage of a partially transformation-defective (td) mutant of MC29 (td10H-MC29) in chicken macrophages. While td10H-MC29 has a reduced ability to transform macrophages in vitro or to induce tumors in vivo, HBI-MC29 transforms macrophages efficiently and induces in vivo a high incidence of lymphoid tumors. Electrophoretic analysis of HBI-MC29 genomic RNA revealed that it has a complexity of 5.7 kilobases, like the RNA of wild-type (wt) MC29, and that it is 0.6 kilobases longer than the 5.1-kilobase RNA of the deletion mutant td10H-MC29. Analysis of the viral RNAs of two clonal isolates of HBI-MC29 by T1 oligonucleotide fingerprinting showed that sequences from the viral transformation-specific region, v-myc, which are deleted in td10H RNA, are present in HBI RNA. Moreover, hybridization of HBI RNA to molecularly cloned subgenomic fragments of wtMC29 proviral DNA, followed by fingerprint analysis of hybridized RNA, showed that the entire v-myc-specific RNA sequences defined previously are present. Hybridization to cloned DNA of the normal chicken locus c-myc shows a close relationship between HBI v-myc RNA and c-myc DNA, especially in the sequences which were deleted from td10H-MC29. T1 oligonucleotide maps of HBI and td10H RNAs were prepared and compared. Total conservation of the oligonucleotide pattern is observed in the overlapping v-myc regions, while the partial structural genes gag and env show some variations, most of which can be directly proven to be due to point mutations or recombination with helper viral RNAs that were analyzed in parallel. Recombination of td10H-MC29 with c-myc, followed by recombinational and mutational changes in the structural genes during passage with helper virus, could be a possible explanation for the origin of HBI.

Animals↗

PubMed1983

Avian oncovirus MH2: molecular cloning of proviral DNA and structural analysis of viral RNA and protein.

Viral RNA, molecularly cloned proviral DNA, and virus-specific protein of avian retrovirus MH2 were analyzed. The complexity and sequence conservation of the transformation-specific v-myc sequences of MH2 RNA were compared with those of the other members of the MC29 subgroup of acute leukemia viruses, MC29, CMII, and OK10, and with chicken cellular c-myc sequences. All T1 oligonucleotides mapping within the 1.3-kilobase coding region of MC29 v-myc have homologous counterparts in the RNAs of all MC29 subgroup viruses and in c-myc. These counterparts are either identical in composition or altered by single point mutations. Hence, the 47,000-dalton carboxy-terminal sequences of the transforming proteins of these viruses and of the cellular gene product are probably highly conserved but may contain single amino acid substitutions. T1 oligonucleotide mapping of MH2 RNA indicated that the MH2 v-myc sequences map close to the 3' end of viral RNA. A genomic library of an MH2-transformed quail cell line was prepared by using the Charon 4A vector system. By screening with an myc-specific probe, a clone containing the entire MH2 provirus (lambda MH2-1) was isolated. Digestion of cloned DNA with KpnI yielded a 5.1-kilobase fragment hybridizing to both gag- and myc-specific probes. Further restriction mapping of lambda MH2-1 DNA showed that about 1.6 kilobases of the gag gene are present near the 5' end of proviral DNA, and the conserved part of v-myc, i.e., 1.3 kilobases, is present near the 3' end of proviral DNA. These two domains are separated by a segment of at least 1 kilobase of different genetic origin, including additional unique sequences unrelated to virion genes. Tryptic peptide analysis of the gag-related protein of MH2, p100, revealed gag-specific peptides and several unique methionine-containing peptides. One of the latter is possibly shared with the polymerase precursor protein Pr180gag-pol, but no myc-specific peptides, defined for the MC29 protein p110gag-myc, appear to be present in MH2 p100. The data on viral RNA, proviral DNA, and protein of MH2 reveal a unique genetic structure for this virus of the MC29 subgroup and suggest that its v-myc gene is not expressed as a gag-related protein.

Avian Leukosis Virus↗

PubMed1983

Repair of the meniscus. An experimental investigation in rabbits.

The healing process of wedge-shaped and longitudinal lesions in the meniscus of the knee was investigated in 74 menisci in 24 Chinchilla rabbits. In four cases the whole meniscus was removed and reimplanted. healing was most evident in the wedge-shaped lesions, which were repaired by fibrocartilage. In longitudinal lesions the repair was markedly avascular and consisted of fibrous tissue only. Suturing did not facilitate the healing process.

Animals↗