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M Cramer

Publications and source records attributed to M Cramer.

At least 37 records · Page 2Linked to original sources
PubMed1989

Evidence for the direct interaction of chicken gizzard 5'-nucleotidase with laminin and fibronectin.

The ectoenzyme 5'-nucleotidase purified from chicken gizzard is shown to specifically interact with laminin and fibronectin, components of the extracellular matrix, by a number of different techniques: (i) cosedimentation with laminin by sucrose gradient centrifugation; (ii) affinity adsorption to both laminin- and fibronectin-Sepharose 4-B; (iii) specific binding to both laminin and fibronectin dotted onto cellulose filters; and (iv) monoclonal antibodies against 5'-nucleotidase are shown to interfere with the interaction of 5'-nucleotidase with laminin and fibronectin. For all the techniques employed, the interactions were found to be specific, since 5'-nucleotidase did not bind to unrelated proteins such as bovine serum albumin or to monomeric actin. The interaction of purified chicken gizzard 5'-nucleotidase could be demonstrated for the hydrophobic enzyme solubilized in detergent and after its reconstitution into artificial phospholipid vesicles. The affinity adsorption experiments indicate that reconstituted enzyme binds more strongly to both laminin and fibronectin. The 5'-nucleotidase employed in this study is anchored to the plasma membrane by a glycan-phosphatidylinositol linker. After treatment with phosphatidylinositol-specific phospholipase C, the enzyme is transformed into a hydrophilic form, for which interactions with laminin and fibronectin could also be demonstrated by the dot-blot technique. Thus controlled cleavage of the phosphatidylinositol linker of 5'-nucleotidase could enable cells to rapidly alter their adhesiveness to certain components of the extracellular matrix.

5'-Nucleotidase↗
PubMed1989

Lymphocyte antigen Leu-19 as a molecular marker of regeneration in human skeletal muscle.

Antigen Leu-19 (Leu19-Ag), a 200- to 220-kDa surface glycoprotein, was originally identified on a subset of human peripheral lymphocytes exhibiting non-major histocompatibility complex-restricted cytotoxicity. Here we report that monoclonal antibody Leu-19 (mAb-Leu19) labels structures in human skeletal muscle: (i) satellite cells, which form the stem cell pool of muscle fiber regeneration, both in normal and diseased muscle; (ii) myotubes and myotube projections in regions of muscle fiber repair; (iii) periodically organized fibrillar structures in areas of regeneration; (iv) the surface of myoblasts and developing myotubes in culture. mAb-Leu19 precipitated a protein of approximately 200 kDa from cultured muscle cells. Our data show that Leu19-Ag is expressed on muscle-specific components of myosegments in repair and thus represents a molecular marker of muscle regeneration. On the basis of this molecular marker and using laser scan microscopy, it is possible to visualize at the light microscopic level hitherto undetectable details of muscle regeneration in routine cryostat sections.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1988

Localization of the putative precursor of Alzheimer's disease-specific amyloid at nuclear envelopes of adult human muscle.

Cloning and sequence analysis revealed the putative amyloid A4 precursor (pre-A4) of Alzheimer's disease to have characteristics of a membrane-spanning glycoprotein. In addition to brain, pre-A4 mRNA was found in adult human muscle and other tissues. We demonstrate by in situ hybridization that pre-A4 mRNA is present in adult human muscle, in cultured human myoblasts and myotubes. Immunofluorescence with antipeptide antibodies shows the putative pre-A4 protein to be expressed in adult human muscle and associated with some but not all nuclear envelopes. Despite high levels of a single 3.5-kb pre-A4 mRNA species in cultured myoblasts and myotubes, the presence of putative pre-A4 protein could not be detected by immunofluorescence. This suggests that putative pre-A4 protein is stabilized and therefore functioning in the innervated muscle tissue but not in developing, i.e. non-innervated cultured muscle cells. The selective localization of the protein on distinct nuclear envelopes could reflect an interaction with motor endplates.

Adult↗
PubMed1988

Measurement of 3':5'cyclic AMP in biological samples using a specific monoclonal antibody.

A fast and sensitive radioimmunoassay for 3':5'cyclic AMP based on a monoclonal antibody has been worked out. Mice were immunized with protein-conjugated 2'-O-succinyl-3':5'-cyclic AMP. The monoclonal antibody detects 0.1 and 1 pmole cAMP with succinyl cAMP (125I)iodotyrosine methyl ester and (3H) cAMP, respectively, as tracers. It shows no cross-reactivity to other adenosine nucleotides up to the millimolar range; cGMP interferes only if present at a 500 fold excess. Plant and animal tissue samples as well as adenylate cyclase activity were analysed directly or after appropriate purification in case of interfering substances. Cyclic AMP levels measured in various tissues by the antibody binding assay correspond to those obtained by HPLC determination using fluorescent etheno-cAMP.

Adenylyl Cyclases↗
PubMed1987

Antigenic determinants shared between HLA-A, -B, -C antigens and H-2 class I molecules modified by bovine beta-2 microglobulin.

The specificity of the mouse class I-specific antibody COB6-3 was examined in detail. It was found to react with the mouse class I molecules H-2Db, Kd, and Qa-2, and with human HLA-A, -B, -C antigens. The specificity pattern of COB6-3, despite its different origin, was similar to that of the monomorphic HLA class I-specific antibody W6/32. Cross-inhibition studies show that on human cells the antigenic determinants recognized by the two antibodies are situated close together and may be identical. On mouse cells, reactivity of both antibodies was generated upon replacement of mouse beta-2 microglobulin (B2m) with its bovine counterpart, but differences in specificity were observed using human B2m.

Animals↗
PubMed1985

An objective assessment of the physiologic changes in the postthrombotic syndrome.

To determine what physiologic changes might contribute to the development of the postthrombotic syndrome, venous outflow, venous refilling time, and valvular competence were assessed in 32 patients (39 limbs) with documented deep venous thrombosis. The follow-up ranged from nine to 144 months (mean, 41 months) after the acute deep venous thrombosis. Pain was noted by 49% of the patients, but more objective end points occurred less frequently (edema, 21%; pigmentation, 26%; ulceration, 3%). Venous outflow was lower in the affected limbs but was not a good indicator of those patients with or without symptoms. Venous refilling time after calf compression was markedly reduced in limbs with incompetent valves (mean +/- SD, 8.4 +/- 3.8 s v 25.3 +/- 12.1 s), as well as in those with edema, pigmentation, and ulceration. It appears that most of the sequelae of the postthrombotic syndrome can be attributed to the loss of valvular function.

Adult↗
PubMed1985

A structural somatic variant of the Kk antigen is generated by point mutation.

We have previously selected structural variants of the Kk antigen from a (C3 X D2)F1 T-cell lymphoma. Those mutants were identified by the loss of certain epitopes defined by monoclonal antibodies. The variant Kk molecule from HK13.S3 cells is no longer recognized by 40% of the trinitrophenyl-specific, Kk-restricted cytotoxic T lymphocytes. Here we report on the primary structure of the altered Kk molecules from the cell line HK13.S3. Comparison with the parental Kk reveals a single base pair exchange, GCG to GTG, that results in an alanine to valine exchange in position 40 of the protein. This observation emphasizes that minor structural alterations in class I molecules may have a strong effect on the H-2-restricted T-cell response.

Amino Acid Sequence↗
PubMed1985

Bioavailability of oral and intramuscular molindone hydrochloride in schizophrenic patients.

This study was designed to assess the bioequivalence of intramuscular molindone hydrochloride and marketed oral molindone. Ten schizophrenic patients (mean age, 30.2 years) received oral molindone in single daily doses of 100 or 150 mg for four to eight days followed by intramuscular molindone in single daily doses of 50 or 75 mg for four days. On the last day each molindone formulation was given, plasma samples were collected at baseline and at 0.5, 1, 2, 4, 6, 8, and 12 hours after administration. The pharmacokinetic measures of area under the curve and maximum concentration show that intramuscular molindone is 1.49 to 1.67 times more bioavailable than oral molindone. This finding indicates that once a patient's acute psychotic episode has been stabilized with intramuscular molindone, therapy can continue without interruption by substituting 1.5 mg of oral molindone for every 1 mg of intramuscular molindone. The time to maximum concentration occurred significantly earlier (P = 0.05) with intramuscular molindone (0.6 hours) than with oral molindone (1.1 hours). Elimination half-life values were approximately two hours for both formulations.

Administration, Oral↗
PubMed1984

Sex differences in inpatients with major depression.

To assess sex-related differences, 53 inpatients with major depression were evaluated with the Zung, Dempsey , and Hamilton depression scales, and part of the Beck scale. Women had more fitful sleep, easy crying, social withdrawal, agitation, somatic anxiety, gastrointestinal symptoms, genital symptoms, crying spells, constipation, and fast heartbeat. Men had more self-dislike and lack of clear mind. Differences in manifestations of major depression may account for misdiagnosis of female depressives as suffering from anxiety or functional insomnia and lead to treatment with anxiolytics rather than antidepressants. Self-dislike and mental clouding may lead male depressives to serious suicide attempts and work failures.

Anti-Anxiety Agents↗
PubMed1984

Identification of human lymphoma cells by antisera to malignancy-associated nucleolar antigens.

The non-Hodgkin's lymphomas (NHL) are a diverse group of human lymphoid neoplasms that have long presented pathologists with formidable diagnostic challenges. These tumors of the immune system are thought to represent neoplastic transformations of most of the recognized stages in T and B lymphocyte ontogeny. Lymphoma cells, however, often simulate their normal lymphocytic counterparts both morphologically and cell surface phenotypically, creating difficulties in discriminating normal from neoplastic lymphocytes. We have used heteroantisera to the human malignancy-associated nucleolar antigen (HMNA) to prospectively evaluate its efficacy in identifying the morphologically neoplastic cells in NHL lesions. In 65 cases of T and B cell histopathologic types of NHL, the antisera reacted with nucleoli in the morphologically and cytogenetically neoplastic lymphoma cells, but not with normal-appearing lymphoid and other cell types present in the lesions. Control specimens from normal and hyperplastic lymphoid tissue also failed to react with anti-HMNA antibodies. Normal activated lymphoid cells in vitro and growth-factor-dependent normal lymphoid cell lines also failed to express the nucleolar antigen(s). These data suggest that the HMNA is a valuable tumor cell marker for neoplastic human lymphoid cell populations and can be used with other types of cell markers for a better definition of the neoplastic cells in NHL.

Adult↗
PubMed1984

Pathophysiology of venous claudication.

Patients with chronic iliofemoral venous obstruction may develop severe thigh pain and a sensation of tightness with vigorous exercise (venous claudication). The discomfort requires 15 to 20 minutes to subside. In the seven patients studied the venous capacitance (VC) and venous outflow (VO) are lower than those of the unaffected limb even at rest. With exercise to the point of pain, the VO was unchanged but the VC decreased even further. The problem appears to rest with the venous collaterals, which have a high and fixed resistance. Because of this high outflow resistance, venous volume increases to near maximum during exercise. With this rise in venous volume, the amount the VC can increase during the period immediately following exercise is further reduced.

Adult↗
PubMed1983

Long-term sequelae of acute venous thrombosis.

The long-term sequelae of acute deep-vein thrombosis were examined prospectively in a series of 61 patients. The location and extent of the involvement were established by either contrast or isotope phlebography. The mean age of the patients was 47 years, with the duration of follow-up averaging 39 months (range, one to 144 months). Pain and/or swelling was noted in 67% of the patients. Pigmentation developed in 15 limbs (23%). Ulceration developed in three patients. The most important factor with regard to prognosis appeared to be the status of the distal deep veins. If these were found to be patent and competent by ultrasonic velocity studies, the long-term outlook was good, both with regard to symptoms and the development of pigmentation. Only 8% of those limbs with normal distal veins were found to have pigmentation during follow-up, as compared with 40% in those with either occlusion or incompetence of the valves.

Acute Disease↗
PubMed1983

Idiotypic and fine specificity analysis of a (4-hydroxy-3-nitrophenyl)acetyl (NP)-specific suppressor T cell hybridoma at the level of cell surface structures, isolated receptor material and functional suppressor factor.

The (4-hydroxy-3-nitrophenyl)acetyl (NP)-specific T suppressor cell hybridoma 7C3-13 was established by fusing splenic B10.BR T cells enriched on NP-coated petri dishes with the AKR thymoma BW5147. 7C3-13 was selected by anti-NPb idiotypic and anti-I-Jk antibodies in microcytotoxicity tests. The hybridoma expressed H-2k, I-Jk, Qa-1, Thy-1.1 as well as idiotypic (binding site-related) and framework Ig VH determinants, while it was negative for I-A, I-E/C, Thy-1.2, Lyt-1, Lyt-2 and Ig constant region determinants. Hapten-binding receptor material could be isolated from 7C3-13 cells on NP-coupled nylon nets and functionally active T suppressor factor (TsF) could be extracted from the hybridoma. Both types of soluble molecules express NPb idiotype, but the TsF carries I-J determinants in addition while the isolated receptors do not. The molecular weight of the isolated receptor material is 80 000, that of the TsF activity is 27 000 and 57 000-64 000, respectively. We thus were able to show that NP-binding molecules can be obtained in the form of cellular surface receptors, isolated receptor material and extracted TsF from one and the same, monoclonal, cell source.

Animals↗
PubMed1983

Somatic variation of H-2Kk expression and structure in a T-cell lymphoma: instability, stabilization, high production and structural mutation.

In the heterozygous T lymphoma line LDHB, variants which have lost the expression of individual H-2 class I genes are spontaneously generated in vitro at a frequency of 10(-1)-10(-2). A cell line (HK13) in which the class I gene Kk is stably expressed (frequency of loss variants less than 10(-4) was selected from LDHB cells by fluorescence activated cell sorting. Further selection of HK13 cells for high Kk expression led to the isolation of the HK22 line which expresses twice as much Kk as HK13. From HK13 and HK22 cells, spontaneous structural variants of Kk having lost individual serological determinants of the Kk wild-type molecule, were isolated by fluorescence activated cell sorting. Such variants occur at a frequency of 10(-6)-10(-7) per cell per generation. The analysis of these variants indicates that they carry mutations in the Kk structural gene and that HK13 cells express a single Kk gene which appears to be duplicated in HK22 cells. We did not find evidence for the generation of variants expressing 'alien' class I products in the LDHB cell line. The instability of class I gene expression in LDHB cells and the transition to stable expression may represent steps of T-cell differentiation in the thymus.

Animals↗
PubMed1983

Affinity-purified antigen-specific products produced by T cells share epitopes recognized by heterologous antisera raised against several different antigen-specific products from T cells.

Heterologous antisera to murine or rat T-cell antigen-binding molecules (T-ABM) were raised in rabbits or sheep. The T-ABM used for immunization were purified by affinity for antigen and did not bear known immunoglobulin isotypes. T-ABM and anti-T-ABM were raised in three separate laboratories. Antisera to T-ABM were exchanged and tested for binding to T-ABM in three separate laboratories. Thus antisera to at least three distinct T-ABM were tested directly for binding to T-ABM or by adsorption of biological activity. Rabbit antisera to murine trinitrophenol (TNP)-specific T-ABM or rat AgB-specific T-ABM bound both murine or rat T-ABM, indicating evolutionary conservation of T-ABM. Similar results were found with sheep antisera to murine T-ABM. In addition, all heterologous anti-T-ABM antisera used bound murine T-ABM specific for TNP, 4-hydroxy-3-nitrophenyl acetate (NP), SRBC, or T-cell membrane proteins with similar structure. Thus, there is a commonality of antigenic determinants between various T-ABM and T-cell membrane homologues which may be T-cell surface receptors for foreign antigen.

Animals↗