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Biomedical subjects

L Nakov

Publications and source records attributed to L Nakov.

18 recordsLinked to original sources
PubMed2000

Common egg envelope antigens are limited to the animal class.

The antigens of the egg envelope (zona pellucida) in mammals are of special interest because of their possible involvement in immunoinfertility and as candidate targets for immunocontraception. Conserved zona epitopes from divergent species may present a suitable source and an animal model for investigation of the above factors. We compared egg envelope antigens from 6 species of vertebrates belonging to 3 different classes in order to demonstrate the existence of shared antigens. Egg envelopes from the trout, carp, turtle, hen, duck and quail were isolated and heat-solubilized. They were tested with rabbit polyclonal antisera against carp, trout and duck egg envelopes by the enzyme-linked immunosorbent assay. The results showed significant cross-reactions among egg envelopes of fish and birds. The examined solubilized preparations did not show cross-reactivity with egg envelopes from any other class, suggesting that divergent species did not share common egg envelope antigens, and that their use may not be appropriate in the investigation of immunoinfertility and immunocontraception in humans.

Animals↗
PubMed2000

[The use of SIT and ELISA to detect serum sperm antibodies in infertile patients].

The existence of natural sperm antibodies in fertile subjects requires the application of additional methods in certain cases of significant, but near to the borderline agglutinating titers, in order to distinguish between pathological and natural sperm antibodies. We applied the sperm immobilization test (SIT) of Isojima and an enzyme-linked immunosorbent assay (ELISA) with sera from infertile patients (n = 66) that have been positive in at least one of the agglutination methods of Kibrick and Friberg. The data were compared with the results for a control group of blood donors (n = 50). It was demonstrated that the positive, but low-titer sera in the test of Friberg were often highly positive in ELISA, while the high-titer sera displayed lower OD values. No such correlation was established by SIT. Probably, it would be practical to use ELISA in cases, where no convincing laboratory data exists for immunity against spermatozoa--relevant, but low agglutinating titers, which can be found in fertile subjects. Besides, SIT and ELISA can recognize antigen-antibody systems different from those identified by the agglutinating tests.

Antibodies↗
PubMed1999

[Frequency of anti-sperm antibodies demonstrated by classical tests for sperm antibodies in patients with unexplained infertility].

The aim of the present investigation was to establish the frequency of sperm antibodies in patients with etiologically unexplained infertility, and to compare the demonstrated frequencies with the results from y control group of y healthy blood donors, as well as with the results of other investigators. The gelatin agglutination test of Kibrick and the tray agglutination test of Friberg were applied to test 244 sera from infertile patients and 50 sera from healthy blood donors at the Laboratory of Immunology of Reproduction, Department of Biology, Medical University of Sofia. For the infertile patients, relevant sperm antibody titers were demonstrated in 2.5% (titer > or = 16) for the Kibrick method, and in 7% (titer > or = 32) for the Fiberg method. The test of Kibrick did not reveal significant antibody titers in the healthy controls, while the test of Friberg showed sperm antibodies in 2% of the blood donors. Fisher's exact test demonstrated extremely significant correlation (p < 0.0001) between the presence of sperm antibodies in sers of patients with unexplained infertility as revealed by the tests of Kibrick and Friberg. Most often mixed agglutinates were demonstrated in the Friberg test. In contrast with the results of other investigators head-to-head agglutinins were observed more often in male sera, while tail-to-tail agglutinins--in female sera. Finally, the results from the present investigation, as well as the analyzed literature data showed a low frequency of anti-sperm immunity in the Bulgarian population. The established high degree of correlation between the tests of Kibrick and Friberg, the good reproducibility of the results and the low cost of these methods confirm their appropriate use for the diagnosis of sperm antibodies in patients with unexplained infertility.

Autoantibodies↗
PubMed1996

Sperm, nuclear, phospholipid, and red blood cell antibodies and isotype RF in infertile couples and patients with autoimmune rheumatic diseases.

PROBLEM: To determine if measuring of nonorgan-specific autoantibodies is useful for better understanding and management of unexplained infertility. METHODS: Sera were obtained from 70 infertile couples, 57 rheumatic patients, and 76 fertile donors. Sperm antibodies (SA) were detected by the tests of Kibrick and Friberg, anti-histones, anti-cardiolipin antibodies, and RF isotypes by ELISA, antinuclear antibodies by indirect immunofluorescence, and anti-red blood cell antibodies by Capture-R. RESULTS: Multiple autoimmune reactivity (both partners positive and/or more than one type of autoantibody involved), higher than naturally occurring in fertile individuals, was found in 55% of the idiopathically infertile couples. IgA-RF was the dominant autoimmune marker. SA revealed similar rates in patients with rheumatic diseases and in infertiles with or without other autoantibodies. CONCLUSION: Although no single autoimmunity marker could predict occurrence of SA, the coincidence of enhanced polyclonal autoimmunity in both partners of infertile couples might potentiate their negative effect on reproduction.

Adolescent↗
PubMed1995

Detection of antibodies toward epididymal sperm antigens--an obligatory step in evaluation of human immunologic infertility?

PROBLEM: To test the relative impact of epididymal versus ejaculated sperm in immunologic infertility. METHOD: Human antibody binding to epididymal and ejaculated spermatozoa was compared by flow cytometry (FCM) since it allows quantitative analysis of viable sperm while ignoring nonsperm cells. To select sera for FCM, GAT, TAT, and ELISA were applied on 145 sera from fertile men, idiopathically infertile and varicocele patients. RESULTS: All GAT/TAT-positive infertile patients, a representative group of varicocele patients and the fertile control, were assessed by FCM. Higher reactivity toward epididymal sperm revealed 18/22 sera while only four out of them bound to ejaculated sperm stronger than the control. All varicocele sera were positive against epididymal while negative against ejaculated spermatozoa. CONCLUSIONS: Epididymal sperm antigens may play a predominant role in some cases of immunologic infertility. Such patients might not be adequately diagnosed and respectively treated due to the limitations of diagnostic procedures applying only ejaculated spermatozoa.

Antigens, Surface↗
PubMed1989

Structure of the plasmalemma of human spermatozoa after treatment with antispermatozoa serum and concanavalin A.

Human ejaculated spermatozoa were treated with antispermatozoa serum as well as with the same serum and concanavalin. A. At both experimental conditions clusters of intramembranous particles both on P-face and on E-face in the acrosomal and postacrosomal regions were seen. The clusters were with different form and size and were built up from different number of intramembranous particles. Large areas with single particles or in some cases devoid of these particles were found out.

Autoantibodies↗
PubMed1989

Soybean agglutinin-binding sites on the human sperm surface.

Some differences in the distribution of lectin-binding sites on the surface of the plasma membrane of acrosomal and postacrosomal regions and tail of ejaculated human spermatozoa were demonstrated by means of horseradish peroxidase labeled soybean agglutinin. The acrosomal region was more densely coated with labeled lectin in comparison with the postacrosomal region. Hapten inhibition with N-acetyl-D-galactosamine was used as control.

Binding Sites↗
PubMedDate not supplied

[Not Available].

The teaching of Biology at the Medical Faculty in Sofia started in 1918 with Botany and Zoology. Already in the next year, it was radically changed by Metodii Popov: 1. Instead of Botany he introduced General Biology, and instead of Zoology - Parasitology (including a general review of the evolution of non-vertebrate animals) and Comparative Anatomy of the Vertebrates; 2. He adapted the teaching of Biology to the needs of the medical education. Those changes were possible thanks to the considerable medical background of M. Popov - it started in 1911 with suitable specialization and research activities, and continued with the establishment of Department of Biology and the Medical Faculty, and the involvement of medics, besides biologists, in its academic staff. During the past years there have been a lot of changes in the curriculum both in its schedule and contents. Some of them were as a result of the development of the biological science and the integration with the other disciples, but some were forced by the administration. Today the students have 90 hours of lectures and a practical course of 90 hours as well. They have at their disposal textbooks on "Biology", "Parasitology" and "Comparative Anatomy of the Vertebrates", as well as, a "Textbook for the practical Course on Biology". Their knowledge is evaluated during the practical course, at two colloquia, and at a practical and theoretical (oral) exam at the end of the first year of education.

Biology↗