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Biomedical subjects

L D Johnson

Publications and source records attributed to L D Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1982

Changes in the distribution of fibronectin and collagen during development of the neonatal rat heart.

Specific antibodies to different types of collagen (I, III, IV and V) and fibronectin were used to investigate the formation of the collagenous connective tissue network in the neonatal rat heart. Immunofluorescence data showed that the staining pattern for fibronectin and Type III collagen was similar as were the patterns for Type I, IV and V collagens. These differences in the staining patterns correlated with previous studies on the development of the connective tissue network and indicated that Type III collagen was the major type of collagen associated with the myocytes. The results of this study showed that by 20 days post-partum the development of the connective tissue network was similar to the adult.

Age Factors↗
PubMed1981

Vaginal adenosis in Cebus apella Monkeys exposed to DES in utero.

Vaginal adenosis comparable to that seen in DES-exposed human newborns exposed to diethylstilbestrol (DES) was observed in 4 (100%) female Cebus apella monkey neonates exposed to DES in utero. Columnar Epithelium lined the vaginal canal and deep crypts in the underlying stroma. The ectocervix was markedly papillary and covered with columnar epithelium that was continuous with the endocervical epithelium. By comparison, the vagina of unexposed newborn and juvenile cebus monkeys up to 15 months of age was filled with a solid core of squamous cells that also covered the cervix and extended into the endocervix. Vaginal adenosis has been produced in mice by neonatal treatment with DES. The mouse model, however, excludes the fetoplacental unit. The cebus monkey provides a model for the investigation of teratogenic effects of intrauterine exposure to DES.

Animals↗
PubMed1980

The biochemical properties of basement membrane components in health and disease.

Basement membranes are complex macromolecular structures which occupy the extracellular space between cells of different histologic types. Biochemically it is composed of Type IV collagen, several noncollagenous glycoproteins including laminin, fibronectin, GP-2 and PYS glycoprotein, and heparan sulfate. Morphologic changes are commonplace in a number of renal diseases. In diabetic glomerular disease, the basement membrane is markedly thickened but the biochemical basis has not been elucidated. In other disease-associated basement membrane changes, altered glycosylation of glycoprotein components has been described. The most important issue is the effect such alterations have on the interaction of basement membrane components and the function of the basement membrane.

Amino Acids↗
PubMed1979

Isolation and characterization of hydroxyproline-containing proteins secreted by a murine carcinoma cell culture.

A collagenous protein was isolated from a murine carcinoma cell culture, which has been shown to synthesize basement membrane. The molecular weight of this protein was estimated to be 155 000. It eluted from carboxymethyl-cellulose in the region near the alpha 1 and beta 11 components of calf skin collagen. 63--69% of the peptide-bound prolines were hydroxylated, and the 4-/3-hydroxyproline ratios ranged from 12 : 1 to 14 : 1. About 95% of the hydroxylysines in the peptide were glycosylated, and almost all of them were in the glucosylgalactosyl dissacharide form. Judging from the posttranslational characteristics, this collagenous protein is probably of basement membrane type.

Animals↗
PubMed1979

Comparison of indirect hemagglutination and indirect immunofluorescence tests with microneutralization tests for detection of type-specific Herpesvirus hominis antibody.

Indirect hemagglutinating and immunofluorescent antibody responses to Herpesvirus hominis types 1 and 2 were compared to neutralizing antibody responses in infected humans from whom H. hominis type 1 or 2 was isolated. The indirect immunofluorescent antibody test was shown to be the most sensitive and specific for primary human infections. The sensitivity and specificity of the indirect hemagglutination and the immunofluorescent antibody tests were shown to be equal to that of the microneutralization test among patients who had primary or recurrent H. hominis type 2 infections. It is suggested that the indirect hemagglutination test is preferable for assaying large populations for previous infection with H. hominis type 2 because it is rapid, easier to perform, and more economical. The intermediate range of titer differences (deltat) between H. hominis types 1 and 2 previously reported to be due to infections with both viruses was shown to occur in all three tests among patients with primary infections with either virus.

Antibodies, Viral↗
PubMed1979

Galactose-1-phosphate uridylyltransferase activity in chronic lymphocytic leukemia.

Galactose-1-phosphate uridylytransferase (E.C.2.7.12) activity was measured in both lymphoid and erythroid cells from patients with chronic lymphocytic leukemia (CLL). Decreased enzyme activity was found in both cell types using two assay methods. The results suggest the presence of an inhibitor of the enzyme in CLL patients. A correlation between decreased uridyl transferase activity and glycogen accumulation in CLL is postulated.

Erythrocytes↗
PubMed1979

Vaginal adenosis in stillborns and neonates exposed to diethylstilbestrol and steroidal estrogens and progestins.

A histologic study was conducted of sagittal sections of the genital tracts of 281 autopsied female stillborns and neonates. The prevalence of vaginal adenosis among 43 offspring exposed in utero to diethylstilbestrol (DES) was 70%, a frequency 18 times greater than the 4% prevalence among 159 unexposed offspring. The relationship of the prevalence of vaginal adenosis to the gestational age at initial exposure was highly significant: 81% of those first exposed during the period of vaginogenesis had adenosis, whereas none exposed after 21 weeks' gestation had adenosis (P1 = 1 X 10(-4)). The relationship of the prevalence of vaginal adenosis to the total dose of DES prior to 22 weeks' gestation also was significant (P1 = 0.02), and this relationship was independent of gestational age at first exposure (P1 =0.01). In contrast, the prevalence of adenosis among 23 offspring exposed to steroidal estrogens and progestins was about the same as that among the unexposed offspring. Vaginal adenosis was unrelated to the complications of pregnancy for which the hormones were given, the calendar year of birth, and the gestational age at delivery.

Diethylstilbestrol↗
PubMed1977

Replication of viral RNA by a defective interfering vesicular stomatitis virus particle in the absence of helper virus.

The genome of a defective interfering particle (DILT) derived from the heat-resistant strain of vesicular stomatitis virus is expressed in vivo without the assistance of infectious helper virus. The rates of RNA synthesis in the presence of cycloheximide (primary transcription) are the same when infections are with equal numbers of physical particles of DILT or virus. With this treatment, DILT synthesizes only 12-17S mRNAs as characterized by size, polarity, and polyadenylylation. In the absence of cycloheximide, DILT-infected cells produce not only these mRNAs but also a 28S RNA species. This RNA, which represents one half of the viral specific RNA, contains newly synthesized full-length (+) and (-) strand DILT RNA. Both strands are found intracellularly as ribonucleoprotein complexes. Without cycloheximide present, the rate of RNA synthesis by DILT was less than that by virus. This curtailment is most likely due to the inability of DILT to synthesize L protein mRNA. An expanded role for defective interfering particles in infection is discussed.

Cells, Cultured↗
PubMed1977

Modification of human DNA-dependent RNA polymerase activity by cyclic GMP.

The effect of low concentrations of cyclic GMP (guanosine 3':5'-cyclic monophosphate) on the in vitro enzymatic activities of DNA-dependent RNA polymerases isolated from human peripheral blood lymphocytes has been investigated. In agreement with earlier studies which employed isolated nuclei as the enzyme source, an increase in the activity of partially purified RNA polymerase I is observed in the presence of cyclic GMP (10(-8) to 10(-10)M). RNA polymerase II activity is inhibited by the presence of cyclic GMP at concentrations between 10(-4) and 10(-10)M. RNA polymerase III activity is stimulated in a bimodal fashion by the presence of cyclic GMP with maximal activity noted at 10(-8) to 10(-10) M and 10(-5)M. In addition, [3H]cyclic GMP binds specifically to chromatographic fractions which are known to contain RNA polymerases I, II and III. This binding to RNA polymerases II and III is apprarently less tenacious as demonstrated by dissociation studies. The observations provide additional evidence for a role for cyclic GMP in the regulation of RNA synthesis.

Cyclic AMP↗
PubMed1977

Differentiation in human amniotic fluid cell cultures: II: Secretion of an epithelial basement membrane glycoprotein.

Cells obtained by amniocentesis for prenatal diagnosis were grown in vitro and examined for the presence of a glycoprotein component epithelial basement membrane. Isolated colonies or clones of amniotic fluid-type cells secrete the glycoprotein, which was identified in association with the cells using indirect immunofluorescent antibody techniques. In addition, the glycoprotein was isolated from tissue culture medium and identified as a component of epithelial basement membranes by passive haemagglutination (PHA) and immunodiffusion assays. Fibroblast-type cells do not secrete the glycoprotein. These results correlate well with the synthesis of type IV collagen by amniotic fluid cells reported in the accompanying paper (Priest et al., 1977) and indicate that amniotic fluid cells are epithelial in origin.

Amniotic Fluid↗