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Biomedical subjects

A Marks

Publications and source records attributed to A Marks.

157 records · Page 9Linked to original sources
PubMedDate not supplied

Synthesis of a brain-specific protein (S100 protein) in a lectin-resistant mutant of a rat glial cell line (C6).

The synthesis of S100 protein increases toward the end of the exponential phase of growth of clonal rat glial cells C6 in monolayer culture. Moreover the synthesis of this protein can be increased by treatment of C6 cells with the lectin succinylated concanavalin A (succinyl ConA). In order to study the relationship between these two inductions of S100 protein we have isolated a cell line resistant to ConA from a population of C6 cells. The resistant cells (C6-ConAR) have less succinyl ConA receptors than C6 cells. In contrast to C6 cells, the synthesis of S100 protein does not increase in C6-ConAR cells after treatment with succinyl ConA. However in both cell types the synthesis of S100 protein increases toward the end of the exponential phase of growth. These results suggest firstly that the induction of S100 protein in C6 cells by succinyl ConA is mediated by an interaction of the lectin with its membrane receptors and secondly that the initial steps in the induction of S100 protein by the lectin are different from the initial steps in the induction of this protein which occurs toward the end of the exponential phase of growth in monolayer culture.

Animals↗
PubMedDate not supplied

Overexpression of a calcium-binding protein, S100 beta, in astrocytes alters synaptic plasticity and impairs spatial learning in transgenic mice.

Recent evidence suggests that slowly propagating Ca2+ waves from astrocytes can modulate the function of neurons. Altering astrocytic calcium processes in vivo may therefore affect neuronal and behavioral phenotypes. Previously, we generated transgenic mice that overexpress an astrocytic calcium-binding protein, S100 beta. Immunocytochemistry and in situ hybridization showed elevated expression in the astrocytes of the hippocampus and other brain regions. Neurons in the hippocampus were negative for S100 beta. In this paper we analyze the hippocampal electrophysiology and learning properties of mice from two transgenic lines. Significant differences were found between the hippocampal slices of normal and transgenic mice in their response to high frequency (100 Hz) stimulation. The overall distribution of post-tetanic excitatory postsynaptic potentials (EPSP) of the slices from the transgenic mice was shifted significantly toward smaller values to a degree that 25% of slices exhibited depression. The altered hippocampal neurophysiology was accompanied by an impairment in a hippocampal-dependent learning task. Transgenic mice showed significant impairment in a spatial version of the Morris water maze, however, they performed normally in non-spatial tasks. Probe trials showed that transgenic mice, though significantly impaired, also acquired spatial information. The results suggested that the impairment was not due to motor dysfunction, impaired vision or motivation of the transgenic mice, findings compatible with a possible hippocampal mechanism. We conclude that overexpression of S100 beta in astrocytes impairs, but does not abolish, the ability to solve a spatial task, and it leads to a significantly decreased post-tetanic potentiation in the hippocampal slice. We hypothesize that the changes are due to calcium mediated processes. Our results support the notion that astrocytes are involved in higher brain functions.

Animals↗
PubMedDate not supplied

The value of immunohistochemical studies using antibody to S100 protein in dermatopathology.

The distribution of S100 protein in normal skin and various tumors involving skin was assessed using rabbit antibody to S100 protein in an immunoperoxidase reaction. In normal skin, S100 protein was detected in the epidermis (melanocytes and Langerhans' cells), dermis (Schwann cells, Pacinian and Meissner's corpuscles, and interdigitating reticulum cells), cells of the sweat gland apparatus, and in chondrocytes. In tumors involving skin, S100 protein was present in nevi, malignant melanomas, histiocytosis X, mixed sweat gland tumors, neural tumors, chondromas, and chondrosarcomas. Detection of S100 protein by immunostaining was useful in understanding the histogenesis of various skin tumors and in assessing the diagnosis and prognosis of a variety of skin lesions encountered in surgical pathology.

Calcium-Binding Proteins↗
PubMedDate not supplied

Effect of feline immunodeficiency virus infection on Toxoplasma gondii-specific humoral and cell-mediated immune responses of cats with serologic evidence of toxoplasmosis.

Serum samples from 89 cats with serologic evidence of toxoplasmosis were identified by using an enzyme-linked immunosorbent assay (ELISA) that detected Toxoplasma gondii-specific immunoglobulin M (IgM) or T. gondii-specific immunoglobulin G (IgG). Concurrent feline immunodeficiency virus (FIV) infection was detected in 36 cats using an ELISA for detection of FIV-specific IgG. The majority of the cats in both the FIV-seropositive and FIV-seronegative groups were male and > 5 years of age. FIV-seropositive cats were more likely to have T. gondii IgM titers without IgG (P < 0.05) or any T. gondii IgM titer (P < 0.05) than were FIV-seronegative cats. FIV-seronegative cats (1328) had a higher T. gondii IgG geometric mean titer than did FIV-seropositive cats (724) and were more likely to have T. gondii IgG titers > 1:2048 than were FIV-seropositive cats (P < 0.05). Cats with serologic evidence of both T. gondii and FIV infections had persistent T. gondii IgM titers for > 12 weeks. Lymphoblast transformation in response to concanavalin A, T. gondii-specific intracellular antigens, and T. gondii-specific secretory antigens was compared in T. gondii seropositive and FIV-seronegative cats, cats with serologic evidence of T. gondii infection alone, and cats with serologic evidence of concurrent FIV and T. gondii infections. Lymphocytes from all but one cat in the FIV-seropositive group responded to concanavalin A. Whereas lymphocytes from FIV-seronegative cats with serologic evidence of toxoplasmosis responded to T. gondii-specific antigens, four of five of the FIV-seropositive cats with concurrent serologic evidence of toxoplasmosis did not.

Animals↗
PubMedDate not supplied

Relationship of lower urinary tract signs to seropositivity for feline immunodeficiency virus in cats.

A group of 41 cats with signs of lower urinary tract disease was compared to a group of 41 cats without any history of disease for prevalence of seropositivity for feline immunodeficiency virus (FIV). The group of healthy cats was similar in age and gender to the group of cats with signs of lower urinary tract disease. Three of the cats with lower urinary tract disease and one control cat were seropositive for FIV. This difference was not statistically significant. The most common cause of lower urinary tract signs was idiopathic. Only 7 cats had urinary tract infection, most associated with perineal urethrostomy or catheterization. Six of the cats with bacterial urinary tract infections were FIV negative.

Animals↗
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Sensitivity of multidrug resistant KB-C1 cells to an antibody-dextran-adriamycin conjugate.

Resistance to adriamycin is an important limitation to the use of the drug in cancer therapy. This resistance is often a manifestation of the multidrug resistance phenotype. Studies with multidrug resistant cell lines in vitro may be useful to design approaches for overcoming the drug resistance encountered clinically. We investigated the possibility of overcoming adriamycin resistance in vitro in a multidrug resistant subline (KB-C1) of human epidermal carcinoma (KB-3-1) cells using antibody-mediated drug targeting. Adriamycin was conjugated through a dextran bridge to a monoclonal antibody (mAb), 10B, which bound to KB-3-1 cells with a Ka of 4 x 10(8) M-1. The conjugate retained immunoreactivity with the target cells. Adriamycin (0.2 micrograms/ml) caused a 50% inhibition of DNA synthesis in KB-3-1 cells, but failed to achieve this degree of inhibition in KB-C1 cells at levels as high as 10 micrograms/ml. In contrast, the 10B-dextran-adriamycin conjugate produced 50% inhibition of DNA synthesis in KB-C1 cells at a concentration of 2.5 micrograms/ml. This was significantly more cytotoxic than adriamycin conjugated to control mAb or bovine serum albumin (BSA). Similarly, a 10B-recombinant ricin A (rRA) immunotoxin was more cytotoxic to KB-C1 cells than free rRA. These results indicate that adriamycin resistance in KB-C1 cells in vitro can be partially overcome by specifically targeting adriamycin to the cells using an 10B-dextran-adriamycin conjugate. This approach may be useful in overcoming adriamycin resistance encountered during the course of cancer therapy.

Antibodies, Monoclonal↗
PubMedDate not supplied

Comparison of growth inhibition of a human ovarian adenocarcinoma cell line by free monoclonal antibodies and their corresponding antibody-recombinant ricin A chain immunotoxins.

Four mouse monoclonal antibodies (mAb) (8C, IgG2a; M2A, IgG2a; M2D, IgG2b; 10B, IgG1) directed against the human ovarian adenocarcinoma cell line HEY were compared for their ability in the free form and as immunotoxins made with recombinant ricin A chain (rRA) to inhibit the growth of HEY cells. For in vitro studies cultured HEY cells were assayed for protein synthesis and plated in agarose to form colonies, and for in vivo studies they were injected intraperitoneally (i.p.) into BALB/c nu/nu (nude) mice at a challenge dose (3 X 10(5) cells) which produced carcinomatosis with ascites, leading to death 30 days following injection. In the free form, mAB 8C was the most potent in inhibiting colony formation in the complement (C)-mediated and ADCC (antibody-dependent cell-mediated cytoxicity) assays in vitro. This mAb was also the only one capable of prolonging survival of mice, both in tumor cell neutralization, and tumor growth inhibition experiments. The four mAb-rRA immunotoxins were effective in inhibiting protein synthesis in vitro in the presence of 10(-7) M monensin. However, in vivo, only 8C-rRA and M2A-rRA were capable of prolonging survival of mice in tumor growth inhibition experiments. Our results suggest that mAb 8C might be useful in the free form and as an 8C-rRA immunotoxin for i.p. immunotherapy of ovarian cancer.

Adenocarcinoma↗
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Inhibition of protein synthesis by monoclonal anti-idiotypic antibody-ricin A chain conjugates in MOPC 315 myeloma cells.

Three monoclonal antiidiotypic antibodies (AIA) to MOPC 315 IgA, G3 (IgG2b), A2 (IgG1) and D10 (a hybrid molecule consisting of gamma 1 and gamma 2a heavy chains), were characterized with respect to their binding constants (Ka) to MOPC 315 mouse myeloma cells. The Ka of G3 and A2 was 10(8)/mole; and that of D10 was 3 X 10(7)/mole. The AIA did not bind to a non-immunoglobulin (Ig) producing subclone of MOPC 315 cells (MOPC 315.36). Immunotoxins derived by conjugating ricin A chain (RTA) to G3 and A2 but not to D10 preferentially inhibited protein synthesis in MOPC 315 over MOPC 315.36 cells. These results suggest that the effectiveness of these immunotoxins assessed on the basis of their targeted cytotoxicity against MOPC 315 cells was dependent on the Ka but not on the Ig subclass of the AIA component of the immunotoxin.

Animals↗
PubMedDate not supplied

Cellular handling of a monoclonal anti-idiotypic antibody in IgA-producing MOPC 315 mouse myeloma cells.

MOPC 315 mouse myeloma cells which produce an IgA (alpha, lambda 2) with dinitrophenol (DNP)-binding capacity were incubated with a [125I]-labeled monoclonal anti-idiotypic antibody (AIA) (D10) to MOPC 315 IgA. AIA D10 bound specifically to the surface of MOPC 315 cells (binding constant 3.0 X 10(7)/mole) but not to cells of a derivative clone which did not produce IgA. Following binding, D10 was taken up intracellularly and localized in a subcellular fraction which sedimented in a Percoll gradient on the light side of the main lysosomal peak. These results indicate that monoclonal AIA to MOPC 315 IgA is selectively bound and internalized by MOPC 315 myeloma cells.

Animals↗
PubMedDate not supplied

Use of peanut agglutinin to assess the acrosomal status and the zona pellucida-induced acrosome reaction in stallion spermatozoa.

Peanut agglutinin (PNA) was used to assess the sperm acrosomal status and the acrosome reaction during gamete interaction in the equine species. PNA exclusively binds to the outer acrosomal membrane of stallion spermatozoa, as was established by transmission electron microscopy. Fluorescein isothiocyanate-PNA (FITC-PNA) labeling was used to monitor sperm acrosomal changes during a prolonged incubation period of 24 hours and during a 2-hours incubation in the presence of 5 microM calcium ionophore A23187. In addition, after a 4-hours preincubation in SP-TALP medium, sperm samples were incubated with matching hemizonae for 1 minute (onset binding) followed by a 60-minute incubation (1-hour binding) of the sperm-hemizona complexes in sperm-free medium to assess the acrosomal status of the bound spermatozoa. For acrosome assessment, spermatozoa and washed sperm-hemizona complexes were air dried onto microscope slides, fixed, permeabilized in ethanol, stained with FITC-PNA, and counterstained with the DNA dye ethidium homodimer. Both zona-bound and non-bound spermatozoa showed similar staining patterns. Acrosome-intact spermatozoa displayed intensively green fluorescence over the acrosomal cap, whereas reacting spermatozoa showed a patchy disrupted image of fluorescence. Sperm cells that completed the acrosome reaction were principally stained on the equatorial segment or not stained at all. During prolonged incubation and during the calcium ionophore treatment, the proportion of spermatozoa with an acrosomal modification (reacting) and a complete breakdown of the acrosome (reacted) increased noticeably. Significant induction of the acrosome reaction was observed within 60 minutes of sperm-zona contact (P < 0.001). In conclusion, a rapid and reliable assessment of the acrosomal status and the incidence of the acrosome reaction of stallion spermatozoa at the zona surface were demonstrated in this study.

Acrosome↗
PubMedDate not supplied

High-throughput DNA sequencing on a capillary array electrophoresis system.

A capillary array electrophoresis apparatus capable of running and analyzing 48 DNA sequencing samples simultaneously has been constructed. The instrument uses a replaceable sieving buffer and incorporates a convenient method for introducing the buffer into the capillaries. Data from laser-induced fluorescence are collected as four separate images, one for each optical channel. The integrated data analysis software employs an open architecture that allows use of any DNA base-calling algorithm. DNA sequencing runs are completed in approx. 1 hr (approximately 500 bases), and instrument turnaround time between runs is less than 15 min. Overall, the instrument throughput is on the order of 720 templates/day, or 360,000 bases/day.

Animals↗