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Biomedical subjects

A Marks

Publications and source records attributed to A Marks.

At least 19 recordsLinked to original sources
PubMed1992

Serologic prevalence of selected infectious diseases in cats with uveitis.

Serologic evidence of infection by Toxoplasma gondii, feline leukemia virus, feline coronaviruses, or feline immunodeficiency virus (FIV) is commonly found in cats with uveitis. Serum samples from 124 cats with uveitis were assayed by use of ELISA for the detection of T gondii-specific immunoglobulin M (IgM), IgG, and circulating antigens (Ag), as well as an ELISA for feline leukemia virus Ag, an ELISA for antibodies to FIV, and an indirect fluorescent antibody assay for antibodies to feline coronaviruses. Serologic evidence of infection by 1 or more of the infectious agents was detected in 83.1% of the samples. Serologic evidence of T gondii infection, defined as the detection of T gondii-specific IgM, IgG, or Ag in serum, was found in 74.2% of the samples. The seroprevalence of T gondii infection was significantly greater in cats with uveitis than in healthy cats from a similar geographic area. Serum samples from cats with serologic evidence of both T gondii and FIV infections were more likely to contain T gondii-specific IgM without IgG than samples from cats with serologic evidence of T gondii infection alone. Cats with serologic evidence of FIV and T gondii coinfection had a higher T gondii-specific IgM titer geometric mean and a lower T gondii-specific IgG titer geometric mean than did cats with serologic evidence of T gondii infection alone. Serologic evaluation for T gondii infection should include assays that detect IgM, IgG, and Ag, particularly in cats coinfected with FIV.

Animals↗
PubMed1992

Targeting of [111In]biocytin to cultured ovarian adenocarcinoma cells using covalent monoclonal antibody-streptavidin conjugates.

Three monoclonal antibodies (mAb) directed against the human ovarian adenocarcinoma cell line HEY, were substituted with maleimide and covalently bonded to thiolated streptavidin. The conjugates were separated from unreacted reagents by successive affinity chromatography on protein A-Sepharose and iminobiotin columns. Purified conjugates consisted of an immunoglobulin (Ig) monomer bound to a streptavidin tetramer through a covalent bond between the Ig molecule and one of the streptavidin subunits. The conjugates were able to specifically target [111In]biocytin to HEY cells in vitro in the presence of human serum and ascitic fluid from ovarian cancer patients.

Adenocarcinoma↗
PubMed1992

In vitro stability of EDTA and DTPA immunoconjugates of monoclonal antibody 2G3 labeled with indium-111.

Monoclonal antibody 2G3 directed against a high molecular weight glycoprotein on breast and ovarian cancer cells was conjugated with bicyclic DTPA (or EDTA) anhydride or benzyl isothiocyanate DTPA (benzyl DTPA) and labeled with 111In. DTPA anhydride was more reactive with the antibody than benzyl DTPA, and kinetics of labeling with 111In were more rapid for DTPA substituted 2G3 than for benzyl DTPA substituted 2G3. On the other hand, 111In-2G3 conjugates prepared using DTPA anhydride were subject to more extensive dimerization and higher losses in immunoreactivity than those prepared using benzyl DTPA. On the basis of measurement of transchelation to transferrin, the stability of 111In-2G3 prepared using DTPA anhydride or benzyl DTPA did not differ during incubation in human plasma for 6 days at 37 degrees C. These results suggest that an important advantage of benzyl DTPA over DTPA anhydride for preparing 111In-labeled antibodies is the prevention of intermolecular (and intramolecular) crosslinking during conjugation which ultimately leads to alterations in conformation and losses in immunoreactivity of the radioimmunoconjugate.

Antibodies, Monoclonal↗
PubMed1992

Magnetic resonance velocity measurements in small arteries. Comparison with Doppler ultrasonic measurements in the aortas of normal rabbits.

RATIONALE AND OBJECTIVES: Magnetic resonance imaging (MRI) can be used to measure motion. This study compares MRI blood flow velocity measurements to Doppler ultrasound velocity measurements in an animal model. MATERIALS AND METHODS: Blood flow in the abdominal aortas of nine normal rabbits was measured using 16-frame, velocity-resolved MRI and Doppler ultrasound. The MRI data were processed into velocity spectra to aid in their interpretation. RESULTS: Maximum velocity measurements made by range-gated Doppler ultrasound were predicted by the maximum velocity values derived from MR velocity spectra with a slope of 0.861, an intercept of -2.78 cm/second, and an R-value of 0.935 in 70 measurements. CONCLUSIONS: Despite the longer time required for the MR measurement, the MR velocity measurement may be useful in the assessment of deep vessels or those obscured by other structures, which are difficult to measure with ultrasound.

Animals↗
PubMed1992

Cell-specific expression of high levels of human S100 beta in transgenic mouse brain is dependent on gene dosage.

The beta-subunit of S100 protein (S100 beta) is highly conserved in the mammalian brain. The gene coding for human S100 beta has been mapped to chromosome 21. In order to study the consequences of overexpression of the S100 beta gene, transgenic mice were generated by microinjection of a 17.3 kilobase human genomic fragment containing the three exons and the transcription control elements of the human S100 beta gene. Mice from four transgenic lines carried approximately 10-100 transgene copies. Northern blotting demonstrated a tissue-specific and gene dose-dependent expression of human S100 beta mRNA in mouse brain. Increased expression of S100 beta mRNA was correlated with an increased production of S100 beta protein. Examination of brain sections by in situ hybridization and immunocytochemistry indicated that S100 beta was localized globally to astrocytes, as well as to discrete neurons in the mesencephalic and motor trigeminal, facial, and lemniscus nuclei in both normal and transgenic mice. In peripheral tissues, human S100 beta was expressed at 10-50-fold lower levels than in brain. The strict gene dosage dependence and cell specificity of transgene expression suggest the presence of a locus control region (LCR) in the human S100 beta gene. The mice tolerated 10-100-fold higher than normal levels of S100 beta gene expression in brain without any gross physical or behavioral abnormalities. The high-level expression and cell specificity of the S100 beta promoter/LCR suggest that it may provide a valuable tool to direct the expression of other transgenic products to specific cell types in the CNS.

Animals↗
PubMed1992

No significant effect of monosomy for distal 21q22.3 on the Down syndrome phenotype in "mirror" duplications of chromosome 21.

Three Down syndrome patients for whom karyotypic analysis showed a "mirror" (reverse tandem) duplication of chromosome 21 were studied by phenotypic, cytogenetic, and molecular methods. On high-resolution R-banding analysis performed in two cases, the size of the fusion 21q22.3 band was apparently less than twice the size of the normal 21q22.3, suggesting a partial deletion of distal 21q. The evaluation of eight chromosome 21 single-copy sequences of the 21q22 region--namely, SOD1, D21S15, D21S42, CRYA1, PFKL, CD18, COL6A1, and S100B--by a slot blot method showed in all three cases a partial deletion of 21q22.3 and partial monosomy. The translocation breakpoints were different in each patient, and in two cases the rearranged chromosome was found to be asymmetrical. The molecular definition of the monosomy 21 in each patient was, respectively, COL6A1-S100B, CD18-S100B, and PFKL-S100B. DNA polymorphism analysis indicated in all cases a homozygosity of the duplicated material. The duplicated region was maternal in two patients and paternal in one patient. These data suggest that the reverse tandem chromosomes did not result from a telomeric fusion between chromosomes 21 but from a translocation between sister chromatids. The phenotypes of these patients did not differ significantly from that of individuals with full trisomy 21, except in one case with large ears with an unfolded helix. The fact that monosomy of distal 21q22.3 in these patients resulted in a phenotype very similar to Down syndrome suggests that the duplication of the genes located in this part of chromosome 21 is not necessary for the pathogenesis of the Down syndrome features observed in these patients, including most of the facial and hand features, muscular hypotonia, cardiopathy of the Fallot tetralogy type, and part of the mental retardation.

Adult↗
PubMed1991

Galactose-conjugated antibodies in cancer therapy: properties and principles of action.

Galactose conjugation of antibodies causes them to be recognized by the hepatic asialoglycoprotein receptor and therefore cleared very rapidly from the blood. In these investigations, some effector functions of galactose-conjugated antibodies were assayed, and several applications to experimental tumors in vivo were demonstrated. Galactose conjugation did not interfere with two antibody functions in addition to antigen binding, namely complement-mediated cytotoxicity and antibody-dependent cell-mediated cytotoxicity. This conjugation procedure was originally developed for its potential use in localized immunotherapy, such as i.p. Injection of galactose-antibody conjugates i.p. demonstrated, more conclusively than other methods that have been used, that the presence of ascites causes prolonged retention of antibody in the peritoneal cavity and that this effect is correlated with the volume of ascites present. In mice bearing i.p. tumor xenografts, i.p. injection of galactose-antibody conjugates resulted in high tumor/nontumor ratios at 28 h after antibody injection, with values of 40:1, 43:1, 77:1, and 11:1 for the blood, kidney, lung, and spleen, respectively, although the ratio was only 4:1 for the liver. Control experiments demonstrated that i.p. injection of unconjugated antibody or a galactose-conjugated nonreactive antibody produced much lower tumor/nontumor ratios. In investigations of possible systemic application of galactose-antibody conjugates, we found that injection of large amounts of an inhibitor that binds competitively to the hepatic receptor, asialo-bovine submaxillary mucin, can block clearance of galactose-conjugated antibodies for 2-3 days. In this way, high blood levels of antibody can be maintained for 2-3 days, thus allowing penetration and binding to solid tumors, followed by very rapid blood clearance. With this approach, using a human carcinoma growing s.c. in nude mice, high tumor/nontumor ratios were obtained 4 days after injection, with mean values of 43:1, 18:1, 17:1, and 15:1 for the blood, kidney, lung, and spleen, respectively, although the ratio for the liver was only 1.7:1. The blood level at this time was 0.04 +/- 0.02% (SD) of the injected dose/g, while the tumor level was 1.69 +/- 1.29% of the injected dose/g. In conclusion, galactose-conjugated antibodies appear to have diverse applications in regional or systemic immunotherapy.

Animals↗
PubMed1991

Imaging of human ovarian tumour xenografts in nude mice using a novel 111In-labelled monoclonal antibody (10B).

Monoclonal antibody (mAb) 10B, directed against the human ovarian adenocarcinoma cell line, HEY, was conjugated with cyclic DTPA anhydride and labelled with 111In. The biodistribution of 111In-DTPA-10B was determined in non-tumour bearing mice and mice bearing subcutaneous (s.c.) and intraperitoneal (i.p.) HEY tumours. The radiolabel was preferentially targeted to s.c. and i.p. tumours in comparison with a control mAb. 111In-DTPA-2G3, which does not bind to HEY cells. Among normal organs, the predominant uptake of radiolabel was into liver and kidney. Subcutaneous tumours were successfully imaged using external gamma scintigraphy following i.v. injection of 111-In-DTPA-10B. The results suggest that 111In-DTPA-10B may be a useful agent for the diagnostic imaging of tumour masses in patients with ovarian cancer.

Animals↗
PubMed1991

Placental-like alkaline phosphatase as a marker of carcinoma-in-situ of the testis. Comparison with monoclonal antibodies M2A and 43-9F.

In an immunohistochemical study of 59 routinely processed tissue specimens from 48 adult testes with isolated carcinoma-in-situ (CIS) changes and of 66 specimens from adult testes without neoplasia, placental-like alkaline phosphatase (PlAP) was shown to be a reliable marker of CIS cells preceding the development of a testicular tumour. Thus, a positive reaction was encountered in all 36 biopsies treated with formaldehyde, or Bouin's or Stieve's fluid. However, only 11 of 23 specimens fixed with Cleland's fluid were immunoreactive for PlAP. None of the non-malignant components of seminiferous tubules, including the large abnormal spermatogonia, reacted with the antibody against PlAP. Besides the antibody against PlAP, monoclonal antibodies M2A and 43-9F were tested on CIS specimens fixed with the above-mentioned fixatives. In the 17 specimens fixed with Stieve's or Bouin's fluid, a positive reaction was obtained in all sections with all three antibodies tested. However, for each antibody at least two specimens gave a weak staining reaction. When all three immunostainings were performed, in each case at least one of them gave a moderate or strong reaction, thus making CIS cells easily detectable. In the samples fixed with Cleland's fluid, a negative reaction was found in one to three specimens, depending on the antibody used. However, at least one of the three antibodies gave a positive reaction if all three immunostainings were applied. In only one of the formaldehyde-fixed paraffin specimens did CIS cells react with the monoclonal antibody 43-9F, whereas M2A gave no positive reaction at all if this method of fixation was used. Thus, the sensitivity of the immunohistochemical staining procedure in the detection of CIS is dependent on the fixative used and increases when immunostainings with all three markers are performed simultaneously.

Adult↗
PubMed1991

Immunohistochemical staining of germ cell tumors and intratubular malignant germ cells of the testis using antibody to placental alkaline phosphatase and a monoclonal anti-seminoma antibody.

Antibody to placental alkaline phosphatase (PLAP) has been previously used in immunoperoxidase (IMP) staining studies of germ cell tumors and intratubular malignant germ cells (ITMGC) of the testis, the latter believed to be the precursor of these tumors. In this study, we compared staining by IMP using monoclonal antibody (mAb) and polyclonal antibody to PLAP with that seen using a mAb, M2A, which was previously shown to react with testicular seminomas and ITMGC. Antibody to PLAP and M2A reacted with different cellular components, as assessed by IMP staining of placenta and prepubertal testis and by Western blotting of seminoma lysates. Antibody to PLAP stained pure seminomas (seven of seven), pure embryonal carcinomas (four of four), and the seminoma (three of three) and embryonal carcinoma (six of six) components of mixed testicular germ cell tumors. M2A stained pure seminomas (26 of 26) and the seminoma component (three of three) of the mixed tumors, but failed to stain pure embryonal carcinomas (zero of four) or the embryonal carcinoma component (zero of five) of the mixed tumors. Both antibody to PLAP and M2A stained ITMGC of the testis. Since M2A stained seminomas and ITMGC but not embryonal carcinomas, seminomas would appear to be more closely related to ITMGC than embryonal carcinomas. This result has led us to speculate on the histogenesis of testicular germ cell tumors.

Alkaline Phosphatase↗
PubMed1991

Heterogeneity in expression of S100 beta mRNA in human melanoma and pleomorphic adenoma demonstrated by in situ hybridization.

S100 protein is a widely used immunohistochemical marker for identification of a number of tumors including malignant melanoma and pleomorphic adenoma of the salivary gland. To extend the detection techniques for S100 protein to the level of its mRNA, sections of malignant melanoma and pleomorphic adenoma were hybridized in situ with a 35S-labeled anti-sense RNA probe complementary to the mRNA for the beta subunit of human S100 protein. Both tumors were labeled with the anti-sense RNA probe but not with a sense RNA probe. In addition, sections of normal and tumor tissues which were known not to express S100 protein on the basis of immunohistochemical studies were not labeled with the anti-sense RNA probe. These results established the specificity of the in situ hybridization technique for the detection of S100 protein mRNA. Although most of the tumor cells in both malignant melanoma and pleomorphic adenoma were labeled with the anti-sense RNA probe, unlabeled tumor cells were also present in their vicinity, suggesting there was a heterogeneity among the cells in both tumor types with respect to S100 protein mRNA expression.

Adenoma, Pleomorphic↗
PubMed1991

Immunoreactivity of S100 beta in heart, skeletal muscle, and kidney in chronic lung disease: possible induction by cAMP.

S100 protein is a calcium-binding protein composed of two subunits S100 alpha and S100 beta, which are expressed selectively by specific cell types. The distribution of S100 beta was examined among various tissues obtained at autopsy from 18 subjects with chronic lung disease and 10 control subjects. The presence of S100 beta in individual cell types was demonstrated by immunoperoxidase staining using polyclonal and monoclonal antibodies specific for S100 beta. In the 10 control subjects, positive staining was seen in a number of cell types that normally produce S100 alpha and S100 beta, (e.g., glial cells, melanocytes, chondrocytes) or only S100 beta, (e.g., Schwann cells). There was no staining of myocardial cells, skeletal muscle fibers, or kidney tubules, which normally produce S100 alpha but not S100 beta. In contrast, in the 18 subjects with chronic lung disease, all of the above cell types stained positively for S100 beta, showing that in these subjects cell types that ordinarily expressed only S100 alpha also expressed S100 beta. We suggest that the observed induction of S100 beta in these cell types seen in subjects with chronic lung disease was mediated by an elevation of cAMP levels secondary to bronchodilator therapy with beta-adrenergic agonists and phosphodiesterase inhibitors.

Chronic Disease↗
PubMed1990

Cloning and expression of the human S100 beta gene.

S100 protein is a low molecular weight, EF-hand, Ca2(+)-binding protein widely distributed and conserved in the central nervous system of vertebrates. The gene coding for the beta subunit of human S100 protein (S100 beta) has been recently mapped to chromosome 21. In order to study the expression of this gene in normal and abnormal brain development, we have isolated and characterized overlapping genomic clones spanning the region coding for human S100 beta and its flanking sequences. The intron-exon organization of the human S100 beta gene is similar to that of the genes coding for several other members of the S100 protein subfamily of EF-hand proteins. The human S100 beta gene is composed of 3 exons, the first of which specifies the 5'-untranslated region, while the second and third each encode a single EF-hand, Ca2(+)-binding domain. The promoter region contains several potential regulatory transcription elements including the cAMP-responsive elements CRE and AP-2. A novel sequence motif, the S100 protein element, situated in close proximity to the TATA box of the genes of several members of the S100 protein subfamily, has been identified. In addition, multiple repeats with similar nucleotide sequence and location to the recently reported beta globin direct repeat elements have been also found in the human S100 beta promoter. A full length (17.3 kilobases) copy of the human S100 beta gene was constructed and transfected into rat glioma C6 cells. Stable transfectants were shown to express correctly initiated transcripts of the human S100 beta gene, indicating that the cloned sequences contain functional regulatory transcription elements.

Amino Acid Sequence↗
PubMed1990

Isotype modulation of idiotypic expression in recombinant isotypic variants of MOPC 315.

The influence of the CH1 domains of various isotypes on the expression of four Id of the IgA 2 mouse myeloma protein MOPC 315 was assessed. To this end, mammalian expression vectors containing the rearranged MOPC 315 VH gene along with the H chain genes of various isotypes were constructed. These vectors were then transfected into the L chain-expressing MOPC 315.26 cell line to produce the rIg. The effect of polyvalency on the ability of Ig to bind anti-idiotypic antibodies was tested by comparing idiotypic expression in a competitive ELISA using reduced and nonreduced MOPC 315 IgA and IgM species. Reduction produced a two- to fivefold decrease in their ability to inhibit the binding of three anti-idiotypic antibodies, but not that of the functionally univalent antibody D10. In contrast, reduction of MOPC 315 IgG proteins did not affect the binding of the anti-Id mAb, indicating that reduction of the interchain disulfide bonds did not alter idiotypic expression. The expression of idiotopes on reduced mouse rIgA, IgM and IgG and human IgG MOPC 315 molecules was then compared. The results showed that both human and mouse IgG recombinant antibodies exhibited an enhanced expression of the idiotopes recognized by antibodies D10 and F1, as compared to MOPC 315 IgA and IgM molecules. In contrast, the expression of idiotopes recognized by A2 and G3 mAb was not influenced by the H chain isotype. These data support the hypothesis that the conformation of certain idiotopes is modulated by the isotype of the CH1 domain.

Alkylation↗
PubMed1990

Inhibition of human tumor growth by intraperitoneal immunotoxins in nude mice.

Intracavitary administration of immunotoxins may play a role in the control of malignant effusions. Selection of immunotoxins for this form of therapy is based on their prior evaluation in preclinical studies. Monoclonal antibodies (mAb) 454A12 (antitransferrin receptor), and 260F9 are directed against antigens which are present on tumor cells in pleural and peritoneal effusions of patients with adenocarcinoma of the breast and ovary. In the present study, immunotoxins derived by conjugating these mAb to recombinant ricin A (rRA) were shown to be cytotoxic to human ovarian adenocarcinoma HEY cells in vitro and in vivo. In the in vitro assay 454A12-rRA and 260F9-rRA were 1000-fold and 10-fold, respectively, more cytotoxic than free rRa against HEY cells, and both immunotoxins were potentiated approximately 1000-fold by monensin. For in vivo studies HEY cells were injected i.p. into nude mice at a challenge dose (3 x 10(5) cells) which produced carcinomatosis with ascites, leading to death 30 days following injection. Administration of 454A12-rRA i.p. following the challenge dose resulted in a complete cure, whereas administration of 260 F9-rRA with monensin significantly prolonged survival. The greater cytotoxicity of 454A12-rRA than 260F9-rRA against HEY cells could be accounted for by the greater number of binding sites and higher internalization rate for 454A12-rRA and mAb 454A12 than 260F9-rRA and mAb 260F9, respectively. These results suggest a potential role for 454A12-rRA and 260F9-rRA plus monensin in the intracavitary therapy of malignant effusions associated with carcinoma of breast and ovary. In the case of 260F9-rRA, this represents the first preliminary indication of the suitability of this immunotoxin for intracavitary therapy of malignancies.

Adenocarcinoma↗
PubMed1990

S100 protein and Down syndrome.

S100 protein is a low molecular weight calcium-binding protein widely distributed in the central nervous system of vertebrates. Recent evidence suggests that S100 protein may play a role in the regulation of glial proliferation and neuronal differentiation. The gene for S100 protein has been mapped to the 21q22 region, a chromosomal locus whose duplication has been implicated in the generation of Down Syndrome (DS). This raises the possibility that abnormalities in S100 protein gene dosage at a critical period during development may be responsible for some of the neurologic abnormalities associated with DS.

Chromosome Mapping↗