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P Berger

Publications and source records attributed to P Berger.

At least 145 records · Page 8Linked to original sources
PubMed1994

The molecular basis for epitopes on the free beta-subunit of human chorionic gonadotrophin (hCG), its carboxyl-terminal peptide and the hCG beta-core fragment.

The molecular basis for antigenic determinants on the free beta-subunit of human chorionic gonadotrophin (hCG beta), its carboxyl-terminal peptide (hCG beta CTP) and the hCG beta-core fragment (hCG beta cf) was elucidated by means of monoclonal antibodies (MCAs). The objective of the present study was to resolve the antigenic topography of these three molecules in terms of epitope identification at different levels of structural organization as well as analysis of their spatial arrangement. An hCG beta cf preparation, a synthetic peptide corresponding to the hCG beta CTP (beta 109-145), overlapping synthetic peptides spanning the entire amino acid sequence of hCG beta, and a reduced and alkylated hCG beta preparation were assayed in a solid-phase one-site enzyme-linked immunoassay and in a soluble-phase direct-binding radioimmunoassay (RIA) or competitive RIA. The antigenic topography was mapped by incorporating the MCAs into two-site binding assays. On the surface of free hCG beta, nine different epitopes (beta 1-beta 9), arranged in three spatially distinct domains, could be distinguished. Epitopes beta 1-beta 7 were located in a single large domain on both hCG beta and the hCG beta cf whereas hCG beta CTP contained two topographically distant determinants, designated beta 8 and beta 9 respectively. All but the two epitopes located on hCG beta CTP (beta 8 and beta 9) were destroyed by reducing and alkylating hCG beta, suggesting that most antigenic determinants are predominantly non-contiguous and require an intact tertiary structure whereas the molecular structure of hCG beta CTP is linear. At a molecular level, amino acid residues spanning hCG beta 45-52, hCG beta 137-144 and hCG beta 113-116 contributed to the formation of epitopes beta 5, beta 8 and beta 9 respectively. We have also shown that the hCG beta cf represents the immunodominant part of the free beta-subunit of hCG, containing seven mainly conformationally determined epitopes, one of which has a share of the sequence beta 45-52. The hCG beta CTP does not play a critical role in the immunologically important tertiary structure of hCG beta and was itself found to be a predominantly continuous sequence also within the native hormone, expressing two spatially distant antigenic determinants located within residues beta 113-116 and beta 137-144 respectively.

Antibodies, Monoclonal↗
PubMed1994

Immunological recognition and clinical significance of nicked human chorionic gonadotropin in testicular cancer.

We studied the physical properties, immunological recognition, and clinical significance of nicked human chorionic gonadotropin (hCGn) in testicular cancer. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions, the beta-subunit of hCGn (hCG beta n) dissociated into two peptides, and, by reversed-phase chromatography, hCG beta n was found to be less hydrophobic than hCG beta. Immunologically, hCGn lacked two epitopes specific for holo-hCG (c1, c2), whereas at least five hCG beta epitopes (beta 1-beta 5) were preserved, and, as a result, recognition of hCGn by different hCG assays varied widely. In 309 sera and 88 urine samples from patients with seminomatous or nonseminomatous testicular cancer, hCG-only, hCG+hCGn, and hCG+hCGn+hCG beta+hCG beta n+hCG beta core-fragment assays gave parallel results. hCGn was more abundant in urine than in serum samples. In conclusion, hCGn lacks two conformationally dependent epitopes of hCG, causing a change in hydrophobicity and explaining its failure to react in certain holo-hCG assays. Recognition of hCGn, however, does not seem to be crucial in the routine use of serum hCG as a tumor marker in patients with testicular cancer.

Chemical Phenomena↗
PubMed1993

Serum glycoprotein hormones and their free alpha-subunit in a healthy elderly population selected according to the SENIEUR protocol. Analyses with ultrasensitive time resolved fluoroimmunoassays.

The SENIEUR protocol was elaborated by a working party of European Community's Concerted Action Programme on Aging (EURAGE) to define strict admission criteria for 'healthy' elderly subjects and young controls for immunogerontological studies. This protocol, which is based on case history, laboratory values and drug consumption, intends to limit the influence of underlying disease and/or medication in order to allow analyses of the aging process per se. In a group of 38 male and 37 female individuals we determined the impact of age and classification according to the SENIEUR protocol on luteinizing hormone (LH), follicle stimulating hormone (FSH), human chorionic gonadotropin (hCG) and free glycoprotein hormone alpha-subunit serum values. Analyses were performed by a set of ultrasensitive time-resolved immunofluorometric assays (IFMA) using our own panel of monoclonal antibodies (MCA). HLH and hFSH, but also hCG and free alpha serum levels increased highly significantly with age in the female population (P < 0.001). In males hFSH, hLH hCG and the free alpha-subunit increased with age. However, only the rise of hFSH and of Free alpha was statistically significant (P < 0.01). The influence of the SENIEUR status on the respective hormone serum levels was determined using two factor analysis of variance, which revealed no statistically significant difference (P > 0.01) between SENIEUR and NON-SENIEUR individuals for all four analytes in both sexes. We conclude that the age related increase of hLH, hFSH, hCG and free alpha is an intrinsic age-dependent phenomen and is not modified by or due to underlying disease or medication as demonstrated by analyses of SENIEUR individuals. Since SENIEUR and NON-SENIEUR individuals had comparable hormone values, a randomly chosen, 'apparently healthy' population seems to be sufficient for physiological studies on serum GPH levels. Lastly, these age related hormonal changes in an extremely well defined healthy population underline the need for age adjusted 'normal' hormone values as elaborated in this communication.

Aged↗
PubMed1993

T cells in cardiac myosin-induced myocarditis.

Autoimmune myocarditis induced by immunization with cardiac myosin can be seen as a virus-free system to analyze the immunopathological mechanisms of certain forms of postinfectious heart disease. Immunodepletion studies have shown that in A.SW mice myosin-induced myocarditis is mediated by both CD4+ and CD8+ cells. The CD4+ subset is at least required for the induction of the autoimmune response, whereas the CD8+ subset seems to play a key role in mediating the myocardial injury. In addition, we found a bias concerning the TCR repertoire, because T cells within the inflammatory heart infiltrate almost exclusively use V beta 8 elements. Furthermore, recent serologic and immunohistologic studies indirectly suggest that the cardiac myocyte is not the target for the anti-myosin response. Rather, the primary target might consist in dendritic cells presenting myosin epitopes even under normal conditions.

Animals↗
PubMed1993

Cocaine-sensitive and -insensitive dopamine uptake in prefrontal cortex, nucleus accumbens and striatum.

Behavioral studies have indicated that the reinforcing effects of cocaine are dependent on inhibition of dopamine uptake in nucleus accumbens and prefrontal cortex. As it has been suggested that dopamine uptake and cocaine-inhibition of dopamine uptake may differ in nucleus accumbens, prefrontal cortex and striatum, we have further characterized dopamine uptake and its susceptibility to inhibition in these three regions. Dopamine uptake was resolved into two processes, which accounts for some of the apparent reported regional differences in sensitivity of dopamine to inhibition by cocaine. One, which is probably associated with uptake into dopaminergic terminals, was sensitive to 6-hydroxydopamine lesions, cocaine, GBR 12909 or ouabain and was dependent on temperature and sodium ion concentration; this was responsible for most of the observed uptake in tissue from striatum and nucleus accumbens, but not from prefrontal cortex. There appeared to be no regional difference in susceptibility of this mode of dopamine uptake to either cocaine or GBR 12909. The other type of dopamine uptake, which represented a significant proportion of the total in prefrontal cortex, but not in striatum or nucleus accumbens, was relatively insensitive to cocaine, GBR 12909 and ouabain and was dependent on temperature, but not sodium ion concentration. In addition, the cocaine-insensitive dopamine uptake was more sensitive to inhibition by dopamine than serotonin, but did not distinguish between dopamine and norepinephrine. The occurrence of cocaine-sensitive dopamine uptake in all examined regions and its equal sensitivity to cocaine and GBR 12909 is consistent with the involvement of nucleus accumbens and/or prefrontal cortex in the reinforcing effects of cocaine.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

Functional and immunological relevance of the COOH-terminal extension of human chorionic gonadotropin beta: implications for the WHO birth control vaccine.

The World Health Organisation (WHO) Task Force on Birth Control Vaccines has selected the pregnancy hormone human chorionic gonadotropin (hCG) as a target molecule for a contraceptive vaccine. A synthetic peptide antigen corresponding to the amino acid sequence 109-145 of the carboxyl-terminal portion of the hCG beta-subunit (hCG beta CTP), which is supposed to elicit hCG-immunoneutralizing antibodies, has been submitted to clinical trials. Recent findings suggest that hCG beta CTP does not play a role in the biological activity of hCG. This raises the question concerning the assumed mechanism of action of the hCG beta CTP-based birth control vaccine. We therefore investigated the immunoneutralizing capacity of antibodies directed against hCG beta CTP. Although it is possible to generate specific monoclonal and polyclonal antibodies for hCG by using hCG beta CTP as an immunogen, it appeared that the biological response to hCG was not affected by such antibodies. The reason for this is that the hCG-antibody-complex is still able to bind to target cell receptors and therefore the intended contraceptive effect should not occur. In addition there is a risk of hazardous possible side effects such as an autoimmune reaction against the ovary because we found that at least one epitope is still accessible for antibody binding on receptor-bound hCG. We conclude from our results that both the efficacy and safety of the WHO vaccine are not yet ensured.

Animals↗
PubMed1993

Variants of human chorionic gonadotropin from pregnant women and tumor patients recognized by monoclonal antibodies.

In biological fluids, hCG and its free alpha- (hCG alpha) and beta-subunits (hCG beta), occur in multiple forms. These various forms differ at the molecular level primarily in glycosylation, but also differ in protein backbone modifications corresponding to the urinary low molecular weight fragment of the hCG beta-subunit (beta-core fragment). This microheterogeneous nature can be demonstrated by isoelectric focusing in which variants are separated into bands with different isoelectric points (pI). To determine whether such isoelectric variants differ in antigenicity and consequently might escape immunoassay detection due to overspecificity of monoclonal antibodies (MCA), urinary pregnancy hCG (NIH, CR123) and tumor hCG preparations, such as a tumor-specific acidic variant of hCG (hCGav) and the hCG beta-core fragment, were separated by isoelectric focusing in the absence or presence of 8 M urea, or by sodium docedyl sulfate-polyacrylamide gel electrophoresis and enzymatically immunostained using an MCA panel directed against 17 different hCG epitopes. MCA against 14 different epitopes accessible on holo-hCG recognized all pI variants of pregnancy holo-hCG or tumor-derived hCGav, as was true for the three MCA recognizing epitopes hidden on holo-hCG but accessible on the free subunits after hCG dissociation by urea. We conclude that each individual pI-isoform of holo-hCG and its free subunits expresses the entire set of epitopes recognized by our MCA panel. The carbohydrate moieties that form a biochemical basis for hCG heterogeneity seem to be neither of major antigenic relevance, nor are they structurally related to any particular epitope. Thus, various glycosylation forms of hCG, hCG alpha, hCG beta, and hCG beta-core in normal as well as in pathological samples should safely be detectable and measureable by immunoassays employing MCA with appropriate subunit specificity.

Antibodies, Monoclonal↗
PubMed1993

[Antigenic determinants of human chorionic gonadotropin (hCG): identification of epitopes and determination of their biological functions, for use in immunometric test systems and development of a fertility regulating vaccine].

Analysing immunologically relevant structures of human chorionic gonadotropin (hCG), a glycoprotein hormone, has bearing on a variety of clinical features. These structures are of importance for the establishment of immunometric assays for the diagnosis and monitoring of pregnancy and hCG producing tumours. Moreover, the development of fertility regulating vaccines by the use of one of the subunits of hCG (hCG beta) or a synthetic peptide corresponding to the carboxyl-terminal peptide thereof (hCG beta CTP, beta 109-145) requires detailed knowledge of the antigenic properties of hCG. It appeared that 16 different antigenic epitopes are localized on the protein backbone of hCG and that the carbohydrate moieties do not contribute significantly to the immunological properties of this hormone. Reduced and carboxylmethylated subunits of hCG, i.e., hCG alpha and hCG beta, express only 1 alpha- and 2 beta-epitopes, the majority of antigenic determinants being destroyed by this chemical procedure. Epitopes of hCG are thus predominantly dependent on the intact tertiary or quaternary structure of the protein. The urinary low molecular weight fragment of hCG beta (hcG beta cf), a predominant molecular fraction in the urine of pregnant women or patients with various tumours expresses 7 out of 9 epitopes of hCG beta (beta 1- beta 7), whereas two antigenic determinants, beta 8 and beta 9, are localized on the hCG beta CTP.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1993

Immunochemical mapping of hCG and hCG-related molecules.

The general observations and experiences of three laboratory groups that have studied the immunochemistry of hCG are summarized. A basic model of the types of antibodies which are most frequently observed has been constructed using the information gathered. Although the immunochemical mapping of the surface of any globular protein is very complex, it was possible to segregate the immune response of mice to hCG into five distinct classes of antibodies based on their binding properties. Each of these types or classes of antibodies can be further subdivided and are obviously binding to different combinations of amino acids on the surface of the hormone. We have attempted to coordinate the nomenclature of the various investigators into a simple scheme for better understanding. The recognition of these different types of antibodies has permitted the development of sensitive and specific immunological measurement systems.

Animals↗
PubMed1993

Effects of cocaine alone and in combination with mazindol in human cocaine abusers.

Mazindol is a catecholamine reuptake inhibitor that blocks binding of cocaine at the dopamine reuptake site. This study was conducted to determine whether the acute administration of mazindol modulates the pharmacological effects of intravenous cocaine in humans. In a crossover study, twelve acute drug conditions were tested in randomized order under double-blind, double-dummy conditions in eight cocaine abusers. Cocaine (0, 12.5, 25 and 50 mg, i.v.) was administered in combination with mazindol (0, 1 and 2 mg given orally 2 hr before the cocaine injection). Physiological and subject- and observer-rated responses were measured. Cocaine and mazindol alone both significantly increased heart rate and blood pressure. Cocaine increased ratings on stimulant-like subjective effect measures, including desire for cocaine; mazindol had mild, stimulant-like subjective effects. There were significant interactions between the effects of cocaine and mazindol on heart rate and blood pressure, with combinations producing significantly large and more sustained increases compared with cocaine alone. There was no evidence that mazindol substantially altered the magnitude or profile of the subjective effects of cocaine, including cocaine-induced craving for cocaine. These results do not support the utility of acute administration of mazindol in the treatment of cocaine abusers through a mechanism of modulation of cocaine's subjective effects. Furthermore, mazindol treatment may increase the cardiovascular risks of cocaine.

Adult↗
PubMed1993

Time-resolved immunofluorometry and other frequently used immunoassay types for follicle-stimulating hormone compared by using identical monoclonal antibodies.

The influence of assay design and quantification system on assay performance was investigated by developing, optimizing, and comparing a time-resolved immunofluorometric assay (IFMA), an immunoenzymometric assay (IEMA), an immunoradiometric assay (IRMA), and a competitive radioimmunoassay (RIA), all performed with the same monoclonal antibodies (MCA) directed against human follicle-stimulating hormone (hFSH). The lowest detection limit (2 ng/L for hFSH-I-3, corresponding to 2.5 mIU of 1st International Reference Preparation of hFSH 78/549 per liter), the widest measuring range (2-160,000 ng/L), and the greatest signal-to-noise ratio (13,000:1 at 160,000 ng/L) were obtained in the IFMA. For analysis of serum samples from 101 male (ages 2-91 years) and 99 female (ages 2-90 years) individuals at a single dilution, 100% of samples were within the measuring range of the IFMA, whereas only 87%, 55%, 32%, and 8% of the sera were for the IRMA, the IEMA evaluated with double-wavelength measurement, the conventional IEMA, and the competitive MCA-based RIA, respectively. These studies demonstrate clear advantages of the IFMA in sensitivity and assay range, which allows reliable and cost- and time-effective determination of hFSH in individuals from infancy to senescence.

Adolescent↗
PubMed1993

Does tumor-derived human chorionic gonadotropin act as a thyroid stimulator in vivo?

To evaluate in vivo the proposed intrinsic thyroid-stimulating hormone (TSH) activity (TSA) of human chorionic gonadotropin (hCG), we monitored over 0.5-1 years the thyroid status of eight patients with hCG-producing non-seminomatous testicular cancer. The patients' sera were analyzed for concentrations of hCG, free thyroxine (fT4), hTSH, and thyroxine-binding globulin (TBG). All patients had excessively high concentrations of hCG (1 x 10(5)-5 x 10(8) ng/L, mean: 1 x 10(7) ng/L) before polychemotherapy, which decreased under successful therapy to physiological values (< 240 ng/L). Although the serum concentrations of hCG varied by more than six orders of magnitude, we saw no changes and no correlation (P > 0.05) between the concentrations of hCG and the concentrations of fT4 and hTSH. Not even when hCG concentrations were greatest (> 5 x 10(7) ng/L) were any signs of hyperthyroidism observed: fT4 (3.5-13 ng/L) and hTSH (9-700 ng/L) were in the physiological range in all patients and remained so during chemotherapy. The results of this longitudinal study were confirmed in analyzing the data for all eight patients (total: 82 samples) cross-sectionally. Again, we found no correlation (P > 0.05) between the concentrations of hCG and fT4 or hCG and hTSH. We conclude that even excessive amounts of testicular tumor-derived hCG do not display any TSH-like activity in vivo.

Chorionic Gonadotropin↗
PubMed1992

Increased ELISA sensitivity using a modified method for conjugating horseradish peroxidase to monoclonal antibodies.

We investigated the importance of monoclonal antibody (MCA) purity and the input molar ratio of horseradish peroxidase (HRPO)/IgG used for MCA conjugation on various immunoenzymometric assay (IEMA) parameters. The sensitivity of IEMAs for human follicle stimulating hormone (hFSH), human chorionic gonadotropin (hCG) and the free alpha subunit of hCG (hCG alpha) could be increased up to 6-fold, whereas non-specific binding remained within tolerable limits (E less than 0.1), when MCAs purified by high performance liquid chromatography (HPLC) using a hydroxylapatite column (HPHT) were conjugated with an input molar HRPO/IgG ratio of four instead of the usual ratio of two.

Animals↗
PubMed1992

Haloperidol prevents induction of the hsp70 heat shock gene in neurons injured by phencyclidine (PCP), MK801, and ketamine.

The non-competitive NMDA receptor antagonists, PCP (phencyclidine), MK801, and ketamine produce psychosis in humans and abnormal vacuoles in posterior cingulate and retrosplenial rat cortical neurons. We show that PCP (> or = 5 mg/kg), MK801 (> or = 0.1 mg/kg), and ketamine (> 20 mg/kg) induce hsp70 mRNA and HSP70 heat shock protein in these vacuolated, injured neurons, and PCP also induces hsp70 in injured neocortical, piriform, and amygdala neurons. The PCP, MK801, and ketamine drug induced injury occurs in 30 day and older rats, but not in 0-20 day old rats, and is prevented by prior administration of the antipsychotic drugs haloperidol and rimcazole. Since haloperidol and rimcazole block dopamine and sigma receptors, and since M1 muscarinic cholinergic receptor antagonists also prevent the injury produced by PCP, MK801, and ketamine, future studies will be needed to determine whether dopamine, sigma, M1, or other receptors mediate the injury.

Amygdala↗