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Biomedical subjects

M J Horn

Publications and source records attributed to M J Horn.

14 recordsLinked to original sources
PubMed1992

Undifferentiated (embryonal) sarcoma of the liver. Pathologic findings and long-term survival after complete surgical resection.

Undifferentiated (embryonal) sarcoma of liver is a rare tumor with a reputed poor prognosis. Four patients with this tumor are reported, of whom three were alive without recurrence 1.5, 2.5, and 12 years after initial complete surgical resection, and two of whom received no adjuvant therapy. The fourth patient, in whom complete surgical resection of tumor was not achieved, died with recurrent tumor at 13 months. The latter tumor differed histologically and consisted mainly of closely packed smaller undifferentiated cells with a higher mitotic and apoptotic rate. Eosinophilic globules, characteristic of embryonal sarcoma, were found in some cases to contain condensed nuclear chromatin, evidence of origin from tumor cells dying by apoptosis. One tumor mainly contained large cysts lined by biliary-type epithelium; this suggested an origin from a multipotent precursor cell able to differentiate along both stromal and epithelial lines.

Adolescent↗
PubMed1991

Computer-assisted work station timing analysis of instrument labor efficiency.

Labor use ratings assigned to instruments by the Workload Recording Method (WRM) do not change with batch size or walk-away time use. The authors evaluated the effect of both on the labor use of the analyzers Paramax B6100 (Baxter Paramax, Irvine, CA) and Ektachem 700 (Eastman Kodak, Rochester, NY) by timing all worked and walk-away intervals on both instruments. Extrapolation of the data to a workload of slightly more than 1.1 million tests showed that reapportionment of tests to various batch sizes caused Paramax-Ektachem labor cost differences to fluctuate between $37,254 and $34,995. When the minimum usable walk-away interval length was varied from 1 to 20 minutes, Ektachem savings over Paramax increased from $8,700 to $61,400. The WRM predicted a constant $29,050 labor cost advantage for Ektachem over Paramax. If other instruments show similar labor use characteristics with respect to batch size and walk-away utility, laboratory managers who do not consider these factors may fail to select the most cost-effective instruments for their laboratories.

Computer Systems↗
PubMed1989

Characterization of murine macrophage Fc receptor-dependent phagocytosis and antibody-dependent cellular cytotoxicity during in vitro culture with interferons-gamma, alpha/beta and/or fetal bovine serum.

Resident and oil-elicited inflammatory peritoneal macrophages (PM phi) from competent C3HeB/FeJ and genetically deficient C3H/HeJ mice were characterized for their Fc receptor (FcR)-dependent binding, phagocytic and ADCC functions during in vitro differentiation under the influence of mouse recombinant interferon-gamma (rIFN-gamma), interferon-alpha/beta (IFN-alpha/beta) fetal bovine serum (FBS), or in serum-free medium. Freshly cultured resident PM phi from C3HeB/FeJ mice had low levels of FcR-mediated phagocytosis in response to mouse monoclonal IgG gamma 2a, IgG gamma 2b or IgG gamma 1, opsonized sheep erythrocytes as compared to oil-elicited inflammatory PM phi from the same strain. Resident PM phi were uniformly upregulated in their FcR-dependent phagocytosis after 24-48 h in vitro culture with FBS to levels approximating that of freshly cultured inflammatory PM phi which were also further upregulated after 24 h in vitro culture with FBS. Both resident and inflammatory PM phi were upregulated largely by an autostimulatory process in that they increased their FcR-mediated phagocytosis in serum-free RPMI-1640 medium without the addition of rIFN-gamma or IFN-alpha/beta, although FBS further augmented FcR upregulation. A synergistic effect of FBS and rIFN-gamma was required for total reconstitution of FcR-mediated phagocytosis of FcR-incompetent C3H/HeJ inflammatory PM phi in that FBS or rIFN-gamma alone only partially reconstituted FcR function, whereas in combination full reconstitution occurred. Thus, macrophages from competent C3HeB/FeJ mice were upregulated in their FcR-mediated functions largely by an autostimulatory process, presumably dependent on endogenous of IFN-beta, whereas, genetically-deficient C3H/HeJ macrophages required exogenous rIFN-gamma in combination with fetal bovine serum for synergistic reconstitution of FcR functions. The uniform upregulation of FcR-dependent effector functions in vitro appears to provide an efficient system for enhanced immune function during differentiation which may be applicable to in vivo situations.

Animals↗
PubMed1988

Photometric assays for FcRI-dependent binding, phagocytosis, and antibody-dependent cellular cytotoxicity mediated by monomeric IgG gamma 2a in murine peritoneal macrophages.

Mouse peritoneal macrophages possess distinct Fc receptors (FcR) for binding the various murine IgG isotypes. FcRI binds monomeric IgG gamma 2a, but not monomeric IgG gamma 2b or IgG gamma 1 with high affinity at 4 degrees C and is sensitive to trypsin degradation. We have assessed the functional consequences of the cytophilic binding at 4 degrees C of monomeric IgG gamma 2a to FcRI of mouse peritoneal macrophages using newly developed photometric microassays for quantification of binding, phagocytosis, and antibody dependent cellular cytotoxicity (ADCC) of post-opsonized sheep red blood cell (SRBC) targets. Dose-dependent binding specificity of monomeric IgG gamma 2a, but not IgG gamma 2b or IgG gamma 1 to FcRI of oil-elicited mouse peritoneal macrophages at 4 degrees C for 2 h was confirmed to display typical saturation kinetics both by the photometric assay and by a cellular enzyme-linked immunosorbent assay (CELISA). Binding of monomeric IgG gamma 2a to macrophage FcRI promoted highly efficient phagocytosis of opsonized SRBC in that most cells that were bound were also rapidly internalized by the phagocytic process during a 1 h incubation at 37 degrees C. Upregulation of FcRI-dependent binding and phagocytosis occurred during 24-48 h in vitro culture of macrophages as shown both by the photometric assays and CELISA. Trypsin treatment of macrophages abrogated FcRI-dependent binding and phagocytosis by monomeric IgG gamma 2a, but had little effect on FcRII-dependent functions. Cytophilic binding of monomeric IgG gamma 2a to FcRI failed to trigger ADCC activation. Thus functional characterization of macrophage FcRI-dependent effector functions confirmed the fidelity of binding specificity of monomeric IgG gamma 2a to a trypsin degradable receptor which mediates highly efficient phagocytosis but fails to initiate the signal for ADCC activation. It appears that passively bound immune monomeric IgG gamma 2a could provide an efficient mechanism by macrophages in vivo for FcRI-dependent immune clearance of soluble or particulate cellular antigens without elicitation of potentially harmful cytolytic factors associated with ADCC activation.

Animals↗
PubMed1979

Methylthiohydantoin amino acids: chromatographic separation and comparison to phenylthiohydantoin amino acids.

Most phenylthiohydantoin (PTH) amino acids and most methylthiohydantoin (MTH) amino acids may be separated from one another by thin-layer chromatography (TLC) using the same sequential development technique with the same two solvents. Similarly, a single solvent system may be used in high-performance liquid chromatography (HPLC) to separate most PTH-amino acids and most MTH-amino acids. When both TLC and HPLC separations are performed on a sample, all MTH-and PTH-amino acids can be uniquely identified. Since many solid-phase protein sequencing techniques generate both MTH-and PTH-amino acids, these analytical systems simplify identification of the amino acid derivatives. Although the chromatographic properties of MTH-and PTH-amino acids are similar, they are not identical (contrary to a previous report).

Amino Acids↗
PubMed1977

Determination of the amino acid sequence of troponon C from rabbit skeletal muscle.

The complete amino acid sequence of rabbit skeletal muscle troponin C (TnC) was determined from studies on overlapping peptides isolated from cyanogen bromide and tryptic digests. TnC was found to be a single polypeptide chain of 159 amino acid residues, including 2 residues of tyrosine and 1 each of cysteine, histidine, and proline. The amino end is acetylated, the calculated net charge at pH 7.0 is -29, and the calculated molecular weight is 17,965. There was no evidence for heterogeneity in the sequence. The previously proposed four apparent Ca2+ binding sites are located at residues 27 to 38, 63 to 74, 103 to 114, and 139 to 150.

Amino Acid Sequence↗
PubMed1975

Bias against genetic hypotheses in adoption studies.

Genetic factors are implicated in the cause of psychopathological disorders whenever the incidence of disorder is greater among the adopted-away offspring of affected parents than among those of control (unaffected) parents. The lack of information about most parents who give their children up for adoption could result in the inclusion of a substantial number of high-risk parents in the control groups. This could bias an adoption study against a genetic hypothesis. The Minnesota Multiphasic Personality inventory scores of two groups of pregnant unwed mothers were compared to those of two other groups: married pregnant women and 18-year-old women. Comparisons disclosed that the unwed mothers had significant elevations on five to the nine clinical scales. Elevations on psychopathic deviancy and schizophrenia were particularly substantial. These results indicate a requirement to select control group parents who are representative of the general population.

Adoption↗
PubMedDate not supplied

A new tool for peptide separation.

A family of reagents has been developed (Pep-Seps) which provide separations of peptides based upon the presence or absence of a single type of amino acid. This separation is achieved through a reversible, covalent attachment of the peptide to the Pep-Seps reagents. Pep-Seps provide a more specific separation than most forms of HPLC and may be used to complement HPLC in peptide separations and isolations. Several specific applications will be discussed.

Arginine↗