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P B Szecsi

Publications and source records attributed to P B Szecsi.

17 recordsLinked to original sources
PubMed2002

Surface immunoglobulin on B lymphocytes as a potential target for specific peptide ligands in chronic lymphocytic leukaemia.

With the aim of producing unique targets for malignant cells we have identified peptide ligands for the clonal surface immunoglobulin isolated from the B cells of a chronic lymphocytic leukaemia (CLL) patient. The peptides were identified from random-peptide phage-display libraries. The obtained ligands bound specifically to the surface of the target lymphocytes as well as to clonal immunoglobulin in lysate from the same cells. Peptide-based antigen mimotopes may have a future use in targeted therapy of CLL and other B-cell-derived malignancies displaying surface immunoglobulin.

Amino Acid Sequence↗
PubMed1999

Identification of patient-specific peptides for detection of M-proteins and myeloma cells.

We have taken advantage of the selection power of phage display technology to define specific peptide mimotopes that recognize individual M-proteins, isolated from patients with multiple myeloma. Preferred amino acid motifs of phages binding to M-proteins were identified in 6/9 patients investigated. Chemically synthesized peptides, corresponding to the phage-displayed peptide inserts, were used to verify the specificity of binding in competition assays. The peptides were able to bind to the M-proteins, as well as the myeloma cells, with high sensitivity and specificity. Employing simple immunological techniques, < 0.01 g/l of M-protein could be quantified, suggesting a novel way for monitoring minimal residual disease in the production of guidelines for adjusting or reintroducing conventional chemotherapy. The peptide mimotopes defined by this technology may be useful as tumour-specific targeting agents and as a tool for purging cells in autologous bone marrow transplantation.

Adult↗
PubMed1995

Cellular origin, complementary deoxyribonucleic acid and N-terminal amino acid sequences of human seminal progastricsin.

The aspartic protease progastricsin (EC 3.4.23.3) is found in all parts of the mammalian stomach and has also been found extragastrically. In humans and monkeys, seminal fluid usually contains high concentrations of progastricsin. Using immunohistochemistry and in situ hybridization, we determined in this investigation the origin of seminal progastricsin to be the epithelia of both the prostatic gland and the seminal vesicles. In addition, Northern (RNA) blotting showed the presence of a 1.8-kb transcript in both tissues. Seminal progastricsin clones from two human prostatic gland cDNA libraries were isolated and sequenced. The combined sequence manifested only six nucleotide differences from the published genomic and gastric cDNA sequence. One conservative base substitution was present in both libraries. N-Terminal amino acid sequencing of all 43 residues of the seminal proenzyme and the first 34 residues of the mature enzyme yielded sequences identical to those deduced from cDNAs derived from both gastric and prostatic origin. The results obtained indicate that gastric and seminal progastricsin are products of the same gene and that the observed molecular differences between the zymogen from the two sources are probably due to posttranslational modifications.

Blotting, Northern↗
PubMed1993

Pepsinogen A and C serum levels in relation to acute NSAID-associated mucosal lesions in healthy volunteers.

Serum pepsinogen has been suggested as a risk marker for the development of gastrointestinal side effects of non-steroidal anti-inflammatory drugs (NSAIDs). The relation between serum levels of pepsinogen A (PGA) and pepsinogen C (PGC) and endoscopic findings in association with short-term NSAID use was investigated in two double-blind, crossover studies in healthy volunteers. Thirty-two male subjects with a median age of 23 years were given naproxen, oxindanac, or piroxicam for 2 weeks. Upper endoscopy was performed by the same investigator before and after each treatment period, scoring mucosal injection and erosive and hemorrhagic lesions separately on 150-mm visual analogue scales. Blood samples for pepsinogen analyses were drawn before each endoscopy. PGA and PGC were analyzed by means of solid-phase radioimmunoassays. Significant amounts of gastroduodenal mucosal lesions were found in all treatment periods, whereas neither PGA nor PGC changed during treatment. Moreover, the initial levels of serum pepsinogen also failed to predict the subsequent development of gastroduodenal lesions. The risk of a type-II error was small in this study, and our results therefore do not support the use of PGA or PGC as a risk marker in this context.

Adult↗
PubMed1992

The aspartic proteases.

The Aspartic proteases (EC 3.4.23) are a group of proteolytic enzymes that share the same catalytic apparatus. Members of the aspartic protease family can be found in different organisms, ranging from humans to plants and retroviruses. The best known sources of aspartic proteases are the stomach of mammals, yeast and fungi, with porcine pepsin as the proto type. The aim of this review is to summarize some of the characteristics of the aspartic protease family.

Animals↗
PubMed1989

The concentration of pepsinogen C in human semen and the physiological activation of zymogen in the vagina.

The relationship between male infertility and the pepsinogen C content in semen has been investigated. The activation of the seminal pepsinogen C in the vagina has been studied under physiological conditions. Samples of semen from 48 vasectomized males and from 46 males of infertile couples were analyzed for pepsinogen C by radioimmunoassay. No correlation was found between the level of pepsinogen C and seminal characteristics, including sperm concentration, motility, and morphologic features. The mean concentration of pepsinogen C was 42.2 micrograms/ml; the first, second, and third quartile were 18.4, 29.6, and 57.6 micrograms/ml, respectively. No significant difference in the level of pepsinogen C was observed between semen of normal quality, semen of reduced quality, and semen with aspermia. Activation of pepsinogen C occurred within 3 h when semen was incubated at pH below 5.0 at 37 degrees C. Intravaginal activation was investigated in six experiments in which semen from two males was instilled in three females. In four experiments with two couples, post-coital activation was investigated. Pepsin C activity in vaginal fluid was detected an average of 3 h (range 2-5 h) and 5 h (4-7 h) after instillation or ejaculation, respectively. Vaginal pH had then been below 4.5 for approximately 1 h. Pepsin C activity was present in the vagina for more than 24 h thereafter. It is most likely that seminal pepsin C is without influence on the fertilizing spermatozoon. However, pepsin C may exert a local effect in the vagina by degrading seminal proteins, thus preventing an immunogenic response in females.

Coitus↗
PubMed1988

Seminal pepsinogen C is not identical with, but is very similar to gastric pepsinogen C.

Human seminal pepsinogen C has been purified and compared with gastric pepsinogen C. The two zymogens cannot be distinguished by amino acid compositions and sequences of the first 28 N-terminal amino acid residues are identical. Apparent immunological identity is observed with polyclonal antisera. Monoclonal antibodies toward seminal pepsinogen C have been produced. One is able to recognize a non-carbohydrate antigenic determinant only present in seminal pepsinogen C.

Amino Acids↗
PubMed1987

Demonstration of pepsinogen C in human pancreatic islets.

Pancreatic tissue from 16 post mortem kidney donors have been examined for the content of pepsinogens. A zymogen with electrophoretic mobility, isoelectric point and molecular weight equal to that of pepsinogen C of gastric origin was found in all specimens. A comparison between pepsinogen C extracted from pancreatic tissue and gastric mucosa demonstrated immunological identity. Quantitative measurements with a radioimmunoassay showed pepsinogen C concentrations in pancreatic tissue three to 80 times higher than those of blood serum. Immunohistochemical staining gave positive reaction for pepsinogen C only in the alpha cells of the pancreatic islets.

Electrophoresis, Agar Gel↗
PubMed1986

An aspartic proteinase from human erythrocytes is immunochemically indistinguishable from a non-pepsin, electrophoretically slow moving proteinase from gastric mucosa.

Antiserum raised against an erythrocyte membrane-attached aspartic proteinase precipitates a non-pepsin gastric proteinase. With a monospecific antiserum raised against the non-pepsin gastric proteinase the two enzymes show immunochemical identity. The isoelectric points of both are between 4.5 and 4.6. By SDS-polyacrylamide gel electrophoresis the two proteinases behave the same way. Under non-reducing conditions the main components show molecular weights around 90 000 and after reduction about 58 000. The proteinase may tentatively be classified as cathepsin E.

Aspartic Acid Endopeptidases↗
PubMed1985

Detection of proteases by clotting of casein after gel electrophoresis.

Clotting of casein provides a sensitive method for detection of proteases after gel electrophoresis. The method is here designated "caseogram." After electrophoresis the gel was equilibrated with 0.15-0.3 M sodium acetate, pH 5.3, and an 1% agarose gel containing 1% skim-milk powder in 0.1 M sodium acetate, pH 5.3, was placed on top of the electrophoresis gel. By incubation at 37 degrees C for 2 h the protease-containing zones produced distinct precipitates in the skim-milk gel. For permanent documentation the skim-milk gel was stained with amido black. The detection limit for pepsin A is 5 ng in the caseogram against 25 ng by hemoglobin digestion at pH 2.5. For calf chymosin it is 1 ng against 100 ng by digestion of hemoglobin at pH 3.5. Caseograms work well after agar gel electrophoresis, after different types of immunoelectrophoresis, and after isoelectric focusing or disc electrophoresis in polyacrylamide gels. Since inert proteins do not interfere with the detection, the method is especially suitable for analysis of crude samples. Samples containing pepsinogen or pepsinogen-like zymogens may be activated at pH 2 before equilibration at pH 5.3.

Animals↗
PubMed1984

Group I pepsinogens in serum. I. Normal range, age and sex relation, diurnal rhythm, seasonal variation, and distribution in ABO blood groups.

The concentration of group I pepsinogens (PG I) in serum was determined in 235 healthy persons and hospital controls. The concentration was significantly higher in males. Correction of PG I with regard to body weight or lean body mass eliminated the sex difference but not the weak correlation with age. The normal range was 0.60-3.3 ng PG I/ml serum/kg body weight. For comparison with other PG I studies another normal range, 46-211 ng PG I/ml serum, was calculated as the 95% interpercentile range of the present PG I concentrations. In a study of diurnal rhythm and in a 6-month study of seasonal variation, no significant variation of PG I in serum was found. Serious non-gastric surgical disease did not influence the PG I level in serum. The PG I levels in blood groups O, A, and B did not differ significantly.

ABO Blood-Group System↗
PubMed1983

Determination of pepsin (EC 3.4.23.1) and gastricsin (EC 3.4.23.3) in gastric juice by rocket immunoelectrophoresis.

Antisera were raised in rabbits against chromatographically purified preparations of pepsin and gastricsin. With these antisera the contents of pepsin and gastricsin in gastric juice were determined by rocket immunoelectrophoresis. The potential content of pepsin and gastricsin of a secondary standard of gastric mucosal extract was calibrated against the chromatographically purified enzymes. This secondary standard was used for routine analyses. The intra-assay and between-assay precision was 3-4% and 6-9%, respectively. Ten healthy volunteers underwent a standard pentagastrin test. The amounts of pepsin and gastricsin determined by rocket immunoelectrophoresis corresponded to the amounts observed by ion exchange chromatography of gastric juice. After stimulation with pentagastrin the secretion of both pepsin and gastricsin was increased about 10 times.

Adult↗
PubMedDate not supplied

Gastricsin-mediated proteolytic degradation of human seminal fluid proteins at pH levels found in the human vagina.

The proteolytic degradation of human seminal fluid proteins at acidic conditions has been investigated. Upon acidification to the pH level of the human vagina, autoproteolysis of most seminal fluid proteins occurred after 30 minute of incubation at 37 degrees C. The degradation was unaffected by inhibitors of serine, thiol, or metallo proteases, whereas pepstatin prevented any proteolysis. The proteins in seminal fluid depleted of the aspartic protease progastricsin did not degrade upon acidification. Readdition of the progastricsin restored the autoproteolytic ability of seminal fluid. Prostate-specific antigen, prostatic acid phosphatase, and Zn-alpha 2-glycoprotein are quickly degraded; albumin, transferrin, and lactoferrin are degraded more slowly. The low molecular weight fragments of semenogelin I and II and especially beta-microseminoprotein are somewhat resistant to proteolysis. These observations strongly suggest that the aspartic protease progastricsin is responsible for the autoproteolysis of seminal fluid proteins under acidic conditions. This suggests that the function of the enzyme is to degrade seminal fluid proteins deposited in the vagina; this in turn may decrease the antigenic load in the vagina and prevent immuno-infertility.

Acid Phosphatase↗