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B Solomon

Publications and source records attributed to B Solomon.

At least 37 records · Page 2Linked to original sources
PubMed1997

Loss of telomerase activity during male germ cell differentiation.

Although the activity of telomerase, an enzyme which synthesizes telomeres de novo and stabilizes telomere length has been demonstrated in the testis, the precise expression of activity in different germ cell types is not known. We examined telomerase activity using a PCR-based telomeric repeat amplification protocol during development of the rat testis from birth to adulthood. Telomerase activity was relatively high from birth to the 4th week of age, and then low between the 5th to 10th week, suggesting that the type A spermatogonial stem cells may be the population which is expressing the highest levels of telomerase activity. To ascertain which germ cells expresses the telomerase activity, purified populations of type A spermatogonia from 9-day old rats, and pachytene spermatocytes, round spermatids and epididymal spermatozoa from adult rats were isolated. While type A spermatogonia expressed very strong telomerase activity, the fractions containing pachytene spermatocytes and round spermatids also expressed telomerase activity, but at comparatively lower levels. Telomerase activity was totally absent in epididymal spermatozoa. Thus, it appears that the telomerase activity is expressed at high levels in the type A spermatogonial stem cells, is down-regulated during spermatogenesis, and is absent in the differentiated spermatozoa.

Animals↗
PubMed1996

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Budgets↗
PubMed1996

Monoclonal antibodies inhibit in vitro fibrillar aggregation of the Alzheimer beta-amyloid peptide.

The beta-amyloid peptide, the hallmark of Alzheimer disease, forms fibrillar toxic aggregates in brain tissue that can be dissolved only by strong denaturing agents. To study beta-amyloid formation and its inhibition, we prepared immune complexes with two monoclonal antibodies (mAbs), AMY-33 and 6F/3D, raised against beta-amyloid fragments spanning amino acid residues 1-28 and 8-17 of the beta-amyloid peptide chain, respectively. In vitro aggregation of beta-amyloid peptide was induced by incubation for 3 h at 37 degrees C and monitored by ELISA, negative staining electron microscopy, and fluorimetric studies. We found that the mAs prevent the aggregation of beta-amyloid peptide and that the inhibitory effect appears to be related to the localization of the antibody-binding sites and the nature of the aggregating agents. Preparation of mAbs against "aggregating epitopes," defined as sequences related to the sites where protein aggregation is initiated, may lead to the understanding and prevention of protein aggregation. The results of this study may provide a foundation for using mAbs in vivo to prevent the beta-amyloid peptide aggregation that is associated with Alzheimer disease.

Amyloid beta-Peptides↗
PubMed1996

Effect of naftifine on neutrophil adhesion.

Effective methods of fungal treatment involve reduction in fungal infections and host inflammatory responses. Naftifine (NF), a topical antifungal agent, is highly active in vitro and in vivo against a wide range of pathogenic fungi. Additionally NF has been shown to inhibit polymorphonuclear leukocyte (PMN) chemotaxis and respiratory burst activity in an irreversible dose-dependent and time-dependent manner. Since leukocyte adherence to endothelia is believed to be one of the initial crucial events in the recruitment of circulating leukocytes to the site of inflammation, we have investigated the in vitro effect of NF on PMN adherence to nylon fiber, BSA-coated glass chamber or polystyrene, and endothelial monolayers via three adherence assays. All three assays demonstrated a statistically significant reduction (p < 0.01-0.001) in PMN adherence to the respective media. In particular, NF (at 30-60 micrograms/ml) significantly inhibited PMN adherence to endothelial monolayers (p < 0.01) as measured spectrophotometrically by the uptake of rose bengal stain. Therefore, NF inhibits PMN adherence to endothelia in our in vitro model system. This inhibition may constitute part of the anti-inflammatory effect of NF.

Allylamine↗
PubMed1996

Effect of monoclonal antibodies in preventing carboxypeptidase A aggregation.

With an increase in temperature, carboxypeptidase A shows a decrease in solubility that is accompanied by loss of enzymic activity and conformational changes leading to its aggregation. In the present study we investigated the suppression of enzyme aggregation via its interaction with two monoclonal antibodies raised against the native protein. The protein aggregation process was monitored by ELISA measurements and determination of residual enzymic activity. As previously found, selected monoclonal antibodies which do not inhibit the biological activity of the antigen and bind with a similar affinity constant to their epitopes on the molecule exhibit a chaperone-like activity in the refolding of their antigen. These antibodies have an inhibitory effect on the aggregation of the enzyme which seems to be related to the location of the antigenic site recognized by each antibody. Identifying the aggregating epitopes' as sequences that are related to the sites where protein aggregation is initiated and preparing monoclonal antibodies against these regions may facilitate the understanding and prevention of protein-aggregation processes.

Animals↗
PubMed1995

Stabilization and surface modification of monoclonal antibodies by 'bi-layer encagement'.

A two step simple procedure for antibody stabilization in soluble form was developed. The antibody is first treated with low molecular weight polyaldehyde (polyglutaraldehyde). Following removal of non-bound polyaldehyde the antibody-polyaldehyde conjugate is crosslinked by polyamine (alkyl amine derivative of polyglutaraldehyde). Feasibility studies were successfully conducted employing monoclonal antibody raised against horseradish peroxidase as model system. The stabilized antibody preparation exhibited improved thermal stability, enhanced resistance to proteolytic digestion and higher 'specific binding activity' in ELISA test, without losing its capability to bind large antigen (enzyme) or being recognized by another antibody (goat anti-mouse IgG).

Antibodies, Monoclonal↗
PubMed1995

Predictive value of hCG level 14 days after embryo transfer.

OBJECTIVE: It has been reported that the quantitative serum hCG level 14 days after embryo transfer (ET) correlated with pregnancy outcome as well as a likelihood of a multiple gestation pregnancy. This prospective study was designed to assess the predictive value of a 14-day post-ET hCG level with pregnancy outcome and multiple gestation pregnancies. METHODS: Patients undergoing in vitro fertilization (IVF) and ET were monitored by serum quantitative hCG levels 14 days after ET. If positive, serial values of hCG were obtained and transvaginal ultrasound was performed 3 weeks after ET and weekly until fetal cardiac activity was seen. Ongoing pregnancies were defined as greater than 20 weeks. RESULTS: One hundred eleven patients had positive serum quantitative hCG levels 14 days post-ET; 89/111, or 80.2%, had ongoing pregnancies. The spontaneous miscarriage rate was, therefore, 19.8% (22/111). If the level was less than 300, the ongoing multiple pregnancy rate was 9% (5/57). If the level was between 300 and 600, the ongoing pregnancy rate was 40% (10/25). If the hCG level was greater than 600, the multiple pregnancy rate was 100% (7/7). CONCLUSIONS: These data support the hypothesis that hCG levels greater than 200 mIU/ml on 14 days post-ET are more likely to have ongoing pregnancies; hCG levels greater than 600 have a high likelihood of a multiple gestation pregnancy.

Chorionic Gonadotropin↗
PubMed1994

Affinity purification of a mannose-binding protein, a sensitive tool in the diagnostics of IgM, via site-directed phosphorylated mannan bound to alumina.

Ca2+ -dependent mannose-binding proteins (MBPs) belong to the family of animal lectins. They perform in vivo as defence molecules that act as opsonins by enhancing the clearance of mannose rich pathogens and have been used in vitro for the purification of IgM. MBPs have been previously isolated by methods based on binding the protein moiety of various mannan species to different matrices. However, the mannan-protein complexes did not have a constant protein content and the yield of the isolated MBPs was variable. In the present study we describe a new approach for the affinity purification of MBPs based on the main polysaccharide moiety of the complex. After removal of residual phosphate groups naturally occurring at the C-3 position of the sugar, which interfere with MBP recognition, the mannan was phosphorylated enzymatically at C-6, at which position the OH group is not required for lectin binding. The enzymatically phosphorylated mannan bound to an alumina column was used successfully for MBP separation from rabbit serum. The mannose-binding protein obtained was used in our study for diagnostic purposes in the identification and determination of very low concentrations of IgM.

Aluminum Oxide↗
PubMed1994

Influence of clinical characteristics and parameters associated with thyroid hormone therapy on the bone mineral density of women treated with thyroid hormone.

Reports of reduced bone mineral density (BMD) in patients receiving long-term replacement and suppression therapy with L-thyroxine have generated considerable interest and controversy. A substantial literature has evolved, with interpretation of conflicting results obscured by a variety of confounding factors. We examined the BMD measurements of 202 white women who were taking thyroid hormone to determine the contribution to BMD of a number of clinical characteristics and parameters associated with thyroid hormone therapy. Measurements of BMD (N = 335 over 2.6 +/- 1.6 years) of the spine (L2-L4) were performed in 195 subjects. The BMD of three sites of the hip was measured (N = 247 over 1.8 +/- 1.1 years) in 157 subjects. The BMD of the proximal radius was also measured (N = 172 over 1.8 +/- 1.2 years) in 124 subjects. Increasing age and a history of previous thyrotoxicosis had a deleterious effect on spine BMD. Body mass index (BMI) was positively correlated with spine BMD. Dose of thyroid hormone, duration of therapy, type of underlying thyroid disease, history of thyroidectomy, or serum-free thyroxine index did not influence either the initial BMD or the change in spine BMD over time. In the hip, age correlated with a decrease, and BMI with an increase in BMD. A history of previous thyrotoxicosis was associated with a decrease in hip BMD at all three sites (0.05 < p < 0.10). No other clinical parameters significantly influenced either the initial BMD or the change in hip BMD over time. Increasing age and dose of thyroid hormone, and a prior history of thyrotoxicosis had a deleterious effect on the BMD at the proximal radius. In summary, thyroid hormone therapy was not associated with a significant effect on BMD of the spine or hip, but a decreased BMD of the proximal radius was related to both previous thyrotoxicosis and to dose of thyroid hormone.

Adult↗
PubMed1993

Eupergit C-coated membranes as solid support for a sensitive immunoassay of human albumin.

A number of commercially available membranes preactivated by coating with oxirane-containing Eupergit C beads were used for diagnostic immunoassay applications. These membranes possess a higher capacity for protein binding than the respective unmodified membranes as measured with fluorescently labelled antibodies. Immobilization of antigens or antibodies as the first step of the assay was achieved by covalent binding of amino groups of proteins to the oxirane moieties introduced onto the membranes. The high performance of the newly developed membranes bearing covalently bound antibodies, was demonstrated by a dot enzyme-linked microalbuminuria immunoassay as compared to unmodified membranes.

Albumins↗
PubMed1992

Affinity purification of antibodies using immobilized FB domain of protein A.

A continuous method for the efficient digestion of protein A into active fragments (FB, Mr = 7000) using immobilized trypsin was developed. These fragments originate from almost identical five-repeated monovalent Fc-binding units of 58 residues each. The fragments obtained were found to be similar to the recently described genetically engineered fragment B. Antibody-binding characteristics of the FB domain and also of intact protein A, immobilized on to adipic dihydrazide-modified Eupergit CB6200 beads, were investigated. Based on the experimental data obtained, a high-performance liquid chromatographic column containing C30N Eupergit C-immobilized FB domain was prepared and its performance in antibody purification was compared with that of Eupergit C-immobilized intact protein A.

Amino Acids↗
PubMed1992

Calcium-modulated conformational affinity chromatography. Application to the purification of calmodulin and S100 proteins.

The purification of proteins by affinity chromatography is based on their highly specific interaction with an immobilized ligand followed by elution under conditions where their affinity towards the ligand is markedly reduced. Thus, a high-degree purification by a single chromatographic step is achieved. However, when several proteins in the crude mixture share affinity to a common immobilized ligand, they may not be resolved by affinity chromatography and subsequent "real" chromatographic purification steps may be required. It is shown that by using properly selected gradient elution conditions, the affinities of the various proteins towards the immobilized ligand may be gradually modulated and their separation may be achieved. This is exemplified by the isolation and separation of a group of Ca(2+)-activated proteins, Calmodulin, S100a and S100b, from bovine brain extract, using a melittin-Eupergit C affinity column which is developed with Ca(2+)-chelator gradients. As expected, separation of the three proteins into individual peaks, eluted in order of increasing affinity to the matrix, was obtained. Sigmoid selectivity curves calculated from the elution volumes under different elution conditions for each of the proteins were obtained, illustrating the chromatographic behaviour of the gradient affinity separation system.

Animals↗
PubMed1992

Microalbuminuria immunoassay based on antibodies covalently conjugated to Eupergit C-coated beads.

OBJECTIVE: To develop a reliable, simple, and sensitive assay for microalbuminuria, based on covalent attachment of anti-HSA to oxirane-bearing polymethylmethacrylate beads (Eupergit CB6200). RESEARCH DESIGN AND METHODS: Anti-HSA antibodies were coupled to CB6200 beads by reaction of their amino groups with the oxirane groups of the matrix. The capability of the beads to bind HSA from standard solutions or urine was evaluated and compared with the state of the art ELISA test. RESULTS: The new bead immunoassay is sensitive and linear in the range of 1-25 mg/L, which is considered the low microalbuminuria range. When HSA levels in urine were tested, the intra- and interassay CV values ranged between 2.7 and 3.9% and between 5.6 and 6.6%, respectively. The long-term storage stability of the antibodies covalently bound on the beads was higher than of the same antibodies adsorbed on ELISA plates. After 16 wk of storage, the CV was about 7.3% with the bead assay, compared with 14% obtained for the ELISA test under the same experimental conditions. CONCLUSIONS: A new procedure for microalbuminuria assay was developed, with Eupergit CB6200 beads as a solid support for covalent binding of the first antibody. Accuracy, sensitivity, reproducibility, and precision of the bead immunoassay were similar to those of commonly used immunoassays, as exemplified by the analysis of HSA in 53 clinical urine samples. The bead assay retains a low degree of variability over long storage periods, and the beads may be reapplied after a simple acid-washing procedure.

Albuminuria↗
PubMed1991

Differences and similarities in the treatment of diffuse goiter in Europe and the United States.

In two separate studies, members of the American Thyroid Association (ATA), and the European Thyroid Association (ETA) were surveyed by questionnaire on their management of Graves' disease. The aim was to determine how expert clinical thyroidologists employ three different therapies which are available for this disorder. Herein we summarize, compare and contrast similarities and differences in the results of these surveys. For the index patient, radioiodine (RAI) was the therapy of choice for 69% of ATA respondents but only 22% of ETA respondents. In contrast, only 30.5% of ATA respondents chose antithyroid drugs as first line therapy compared to 77% of ETA respondents. There was consensus on the relative lack of a role for thyroidectomy. The implications of these differing approaches to the treatment of hyperthyroidism due to Graves' disease are discussed.

Adult↗
PubMed1991

Differences and similarities in the diagnosis and treatment of Graves' disease in Europe, Japan, and the United States.

In three separate studies, members of the American Thyroid Association (ATA), the European Thyroid Association (ETA), and the Japan Thyroid Association (JTA) were surveyed by questionnaire on their management of Graves' disease. The aim was to determine how expert clinical thyroidologists employ diagnostic procedures and the three different therapies that are available for this disorder. In this report, we identify, summarize, compare, and contrast similarities and differences in the results of these surveys in these three different regions of the world. In general, ATA members used fewer diagnostic tests than did their European or Japanese colleagues. For the index patient, radioiodine was the therapy of choice for 69% of ATA respondents but only 22% and 11% of ETA and JTA respondents, respectively. In contrast, only 30.5% of ATA respondents chose antithyroid drugs as first-line therapy compared to 77% of ETA and 88% of JTA respondents. There was consensus on the relative lack of a role for thyroidectomy except for narrow indications. The implications of these differing approaches for the diagnosis and treatment of hyperthyroidism due to Graves' disease are discussed.

Adolescent↗