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Biomedical subjects

A P Kozlov

Publications and source records attributed to A P Kozlov.

At least 19 recordsLinked to original sources
PubMed2005

Experimental study of human expressed sequences newly identified in silico as tumor specific.

In our previous studies, we used global computational differential display of ESTs that belong to UNIGENE clusters and identified human sequences differentially expressed in human tumors, as well as a considerable amount of transcripts represented only in tumor-derived cDNA libraries. Most of the tumor-specific EST clusters are derived from the plurality of the tumor types originated in tissues of both ectodermal and mesodermal origin. We found that many of such tumor-specific ESTs do not contain long open reading frames and cannot be classified as protein-encoding genes. To experimentally assess patterns of expression of these EST clusters, we studied four of them in PCR experiments on Clontech MTC panels. The experimental data confirm the results obtained by in silico screening, i.e. tumor specificity of their expression. We suggest that a significant increase in the expression of non-coding RNA is a fundamental feature of cancer cells, and that such transcripts could serve as markers for the diagnosis or monitoring of human malignancies.

DNA, Neoplasm↗
PubMed2005

[Potential of different kinds of laser irradiation in treatment of benign and malignant tumors of facial skin].

The use of neodymium, holmium and diode lasers proved highly-effective in the treatment of facial skin cancers stage I-II (3,051)( basalioma--2,804, recurrent basalioma--165, squamous cell tumor--82) and benign tumors (2,157). Relapsed basaliomas after treatment from Pulsar-1,000 Ladoga- neodymium were reported in 1.6 and 3%, respectively. When pulsed neodymium lasers were used, repeat relapsed basalioma and recurrences of squamous cell cancer were detected in 4.2 and 4.9%, respectively. Overall malignancy recurrence frequency was 2,0% which was less than that after radiotherapy and surgery. Since the radiation penetration capacity of neodymium lasers is relatively high, their application is preferable in treatment of facial skin cancer stage I-II as well as exophytic or in-depth benign tumors. Holmium and diode lasers are better suited for destruction of superficial benign tumors. Good results should not be expected unless the right choice of radiation modality parameters, which take account of tumor localization and clinical course pattern, is made.

Aged↗
PubMed2004

Host-dependent serum specificity to the V3 domain of HIV-1.

The previous studies of anti-HIV-1 humoral immune response have found the stable individual structural bias in the antibody production that reflects the changes in the immune functional network caused by HIV-1. The correlation between antigen structure, in particular the V3 domain of HIV-1, and the serum specificity to the structure remains unclear. To clarify the role of host individual factors in the serum specificity, we used the slightly modified HIV-1 serotyping methodological approach for the sera of the patients infected with HIV-1 with a different level of genetic similarity. Substantial discrepancy between serum specificities and antigen structure was found. Patients infected with HIV-1 carrying similar and identical V3 sequences had significantly different serum specificities. The opposite situation was often observed as well. The results of the study suggest that the influence of the V3 loop structure in the development of humoral immune response to the V3 loop is substantially modified in a patient-specific manner.

Antibody Formation↗
PubMed2004

Drug use and sexual risk behaviours among female Russian IDUs who exchange sex for money or drugs.

Countries of the former Soviet Union are experiencing the steepest increases in annual HIV incidence in the world. Over 80% of registered HIV cases in Russia have occurred among intravenous drug users (IDUs), but current conditions set the stage for a heterosexually-transmitted epidemic. IDUs who also trade sex for money or drugs may serve as a conduit, or 'bridge' group, through which HIV could make inroads into the general Russian population. The present study examined the prevalence of sex trading among female Russian IDUs, and further examined drug use, sexual behaviour, and perceived vulnerability in this group. Female IDUs (n=100) in St Petersburg, Russia participated; 37% reported a history of sex trading. This group reported a mean of 49.5 male sexual partners in the previous month and an average of 15.4 unprotected vaginal intercourse acts in the previous 30 days. A significant minority (44%) also reported sharing injection equipment with others. Mathematical models to calculate risk estimates for HIV seroconversion indicated that participants were at significant risk of contracting HIV and infecting sexual partners. Despite significant rates of risk behaviours, most participants perceived themselves to be at little risk of contracting HIV. Effective HIV prevention programmes targeted at this group are urgently needed and are likely to be a cost-effective step in curtailing the spread of HIV in the region.

Adolescent↗
PubMed2004

[Some approaches to elaborating vaccines against the HIV infection].

A variety of approaches to creating vaccines against the HIV-infection are discussed in the paper. It is demonstrated that vaccines can be used both for treatment and prevention. They can be synthetic, DNA-vaccines and vector-type ones based on the attenuated recombinant strain of Salmonella. Apart from gp120, reverse transcriptase and tat-gene products can be used as the antigen.

AIDS Vaccines↗
PubMed2002

HIV risk characteristics and prevention needs in a community sample of bisexual men in St. Petersburg, Russia.

A new and understudied HIV epidemic is quickly unfolding in the Central and Eastern European countries of the former Soviet Union. Men who have sex with men (MSM) in Russia constitute a population highly vulnerable to sexually-transmitted HIV infection. In a community sample of 434 Russian MSM accessed in gay venues in St. Petersburg, 126 had had both male and female partners in the past three months. In this paper, we report on their risk characteristics. Forty-five per cent of men reported recently engaging in unprotected anal intercourse with their male partners. Respondents had a mean of 3.3 male and 3.4 female partners in the past three months, and most had multiple male and female partners in this time period. There were serious and significant gaps in the AIDS risk knowledge levels of these men, and most believed they had no personal contact with HIV-positive people. Bisexual men were more likely than exclusively gay men to have engaged in commercial sex and tended to have lower AIDS risk knowledge. Although they did not differ in average age, bisexual compared to gay men more recently had their first sex with a man. Multivariate logistic and linear regression analyses showed that condom and safer sex attitudes, perceived norms, AIDS risk knowledge and age at first sex with a man were independent predictors of high-risk behaviour among bisexual men. HIV prevention interventions for bisexual men should address their sexual practices with both male and female partners, correct misconceptions about risk, address behaviour practices rather than gay identity, and recognize risk issues faced by the female partners of bisexual men.

Adult↗
PubMed2002

[Susceptibility of wild and knockout p53 FVB/N line mice to benz(a)pyrene-induced subcutaneous sarcoma].

Susceptibility to benz(a)pyrene (BP) has been compared between wild and knockout p53 homo- and heterozygous FVB/N, C57BL/6 and NMRI line mice. Each group included 34-80 animals. Each animal was injected 2 mg BP, s.c., in sunflower oil solution. The animals were followed up for 24 weeks. Fibrosarcomas arose at the site of injection in: wild FVB/N line mice--93%; FVB/N heterozygous--100%; p53 homozygous knockout--95%; C57B1/6--84%, and NMRI mice--83%. Mean latent period was 68, 66, 69, 112 and 109 days, respectively. Hence, FVB/N line mice developed tumors much earlier than C57B1/6 or NMRI did, suggesting their higher susceptibility to carcinogenic BP injection. No significant difference in susceptibility to carcinogen versus p53 expression was reported.

Animals↗
PubMed2001

In silico screening for tumour-specific expressed sequences in human genome.

A computer-based differential display tool named HsAnalyst has been developed and successfully used for the comparison of expression patterns in a set of tumours versus a set of normal tissues. A list of EST clusters highly represented in tumours and rarely observed in normal tissues has been developed as a resulting output file of the program. These differentially expressed EST clusters (genes) can be useful for developing new tumour markers and prognostic indicators for a wide set of human malignancies. Tumour-specific protein-coding genes may be considered a manifestation of tumour-specific gene expression.

Databases, Genetic↗
PubMed2001

Predictors of HIV risk behavior among Russian men who have sex with men: an emerging epidemic.

BACKGROUND: Russia is experiencing one of the sharpest increases in HIV incidence in the world. Almost no research has examined patterns of risk behavior among Russian men who have sex with men (MSM). DESIGN AND METHODS: A total of 434 MSM were surveyed in all of St. Petersburg's gay-identified clubs during June 2000. Men completed questionnaires about their sexual practices, AIDS risk knowledge, safer sex attitudes, behavior change intentions, perceived safer sex norms, and fatalism. RESULTS: Most MSM were bisexual; 79% had female partners in their lives and 37% had female partners in the previous 3 months. Sexually transmitted disease treatment was reported by 32% of the men, 23% had sold sex to gain money, and knowledge about critical HIV risk-reduction steps was low. Of all men surveyed, 38% had unprotected anal sex in the previous 3 months, consistent condom use was reported by only 30% of men, and most recent anal intercourse occasions 37% of particpants'. Regression analyses showed that high-risk behavior was predicted by poor safer sex attitudes, weak behavior change intentions, low knowledge about AIDS risk, perceived peer norms that did not support safer sex, and having a boyfriend. CONCLUSION: To avert a widespread epidemic, HIV prevention interventions for Russian MSM are critically needed. Factors predicting risk were consistent with those found among MSM in other countries early in the HIV epidemic. However, unique cultural factors, including frequent bisexual behavior, the 'newness' of openly gay communities in Russia and lack of community experience in dealing with AIDS, require HIV prevention program tailoring.

Adult↗
PubMed2001

HIV risk behavior and risk-related characteristics of young Russian men who exchange sex for money or valuables from other men.

One of the world's newest HIV epidemics is emerging now in Russia and other countries of Central and Eastern Europe. We report on the HIV risk characteristics of young Russian men who exchange sex for money or valuables, a group that constitutes almost one-fourth of men surveyed recently in gay-identified venues in St. Petersburg. Among 96 MSM who have sex for economic gain, most reported multiple male and female partners, 45% had unprotected anal intercourse with their male partners in the past three months, and many not only received but also gave money or valuables themselves to their male partners. Relative to men who did not give sex for economic gain (n = 326), those who did were younger (n = .0001), less well-educated (p = .0001), and more often unemployed (p = .02). They also were less knowledgeable concerning even basic HIV risk reduction steps (p = .02) and held many misconceptions about safer sex. Men who exchanged sex for economic gain had more male (p = .001) and female partners (p = .01) in the past three months than men who did not, and one-third had been treated for STDs. In the context of Russia's rapid cultural and social changes, economic turmoil, and gay communities not yet experienced in AIDS, HIV prevention programs must be tailored to risk patterns and dynamics different than those found in the gay communities of many western countries.

Adolescent↗
PubMed2000

The effects of local application of D2 selective dopaminergic drugs into the medial prefrontal cortex of rats in a delayed spatial choice task.

The study examined the effects of modulation of dopamine D2 receptors-mediated neurotransmission in the rat's prefrontal cortex (PFC) on storage and executive components of working memory. Rats were trained on delayed (delay interval, 3 s) and non-delayed choice in a U-maze. The prominence of proactive interference was evaluated by sorting errors in a current trial on the basis of animal reactions in a preceding trial. The erroneous runs to the same arm of the maze as in the previous trial were identified as the repetitions (RE) and the erroneous runs to the other arm in comparison with the previous trial were classified as alternations (AE). The bilateral microinfusion of D2 agonists PPHT (0.004 microg, 0.04 microg, 0.4 microg/1 microl) into medial wall of the PFC produced a dose-dependent increase in the error rate of the delayed-response task and did not influence non-delayed choice. In delay condition PPHT enhanced the perseverative tendencies (the rate of RE was significantly higher than the rate of AE), in non-delayed choice the erroneous performance was mainly represented by AE. In contrast, the infusion of D2-receptor antagonist sulpiride (0.03 microg, 0.3 microg, 3 microg/1 microl) increased the accuracy of delayed choice and changed the mode of intertrial dependence-rats made significantly more AE than RE. The results are discussed in terms of the involvement of D2 receptor dependent transmission of the PFC in different cognitive processes related to the delayed performance in U-maze (within-trial short-term storage of information versus dynamic control of between-trials working memory processing).

Animals↗
PubMed1999

[Radiobiological assessment of radiation injuries in various regimens of total body irradiation].

A radiobiological evaluation of dose-time regimens of total body irradiation (TBI) using a single-exposure multi-target (MM) and a linear-quadratic (LQM) models of cell destruction has been carried out. An equivalent of single dose of acute irradiation was used as a criterion of biological effect of LQM. The latter proved useful in analyzing all kinds of dose-time regimens of TBI including those employing different doses. Practically speaking, single exposure to 5 Gy and irradiation by three daily fractions in a total dose of 10 Gy may be recommended for wide clinical application.

Bone Marrow↗
PubMed1996

Gene competition and the possible evolutionary role of tumours.

The evolutionary role of tumours might consist of providing the conditions for the expression of evolutionary new genes and thus in providing the material for the origin of new cell types. To approach this concept the principle of gene competition is essential. With an increase in gene number in the genomes of the evolving multicellular organisms the enforcement of gene competition should take place. Therefore, the pre-existing cell types possess limited possibilities for the expression of evolutionary new genes. Like evolutionary new genes originated from extra copies (duplicates) of old genes, evolutionary new cell types had to originate from extra cells which were not functionally necessary to the organism. Tumours could have supplied the evolving multicellular organisms with extra cells for the expression of originating evolutionary new genes. Of course, on the basis of this proposal only tumours at the earlier stages of progression are considered to be meaningful, or some kind of tumour-like processes, but not malignant tumours at late stages of progression. The evolutionary new genes originate in the DNA of germ line cells but not in DNA of tumour cells. Until the moment of their expression in the tumour cells these genes could stay silent. After the expression of these genes tumour cells should acquire the function in the organism, differentiate and lose their previous autonomy. The organisms with a new cell type should then be selected against their fitness and competitive abilities.

Animals↗
PubMed1996

[Comparative evaluation of the effectiveness of surgical treatment and pulsed laser therapy for malignant skin melanoma, stage I].

The report deals with a comparison of the effectiveness of surgical (300 cases) and pulsed laser treatment (wavelength of 1,060 nm, pulse duration-1 ms) (230 cases) for skin melanoma, stage I, degree I-IV invasion (Clark). All patients were followed up for 5 years and longer. Following laser therapy, local recurrencies were detected in 0.75% while regional and distant metastases were identified in 24.8%; in 45.6%, they were detected within the first 12 months of follow-up. Treatment by radiation from a powerful pulse source proved effective for cutaneous melanoma, stage I, degree I-IV invasion (Clark). Total 5-year survival was 83.2%. All patients with degree I invasion have survived 5 years, and are still alive, degree II-92.3%, degree III-85.7% and degree IV-80.5%. For surgical treatment, total 5-year survival was 78.7%. All patients with degree I invasion have survived 5 years and are still alive, degree II-85.5%, degree III-78.9% and degree IV-68.4%.

Female↗
PubMed1996

[The potentials of impulse laser radiation in treating I-stage melanomas of the skin].

An analysis of observation of 265 patients during 1-22 years has shown that the radiation of powerful impulse lasers is an effective means of treatment of superficial and slightly risen skin melanomas of the 1st clinical stage having the I-IV level of invasion according to Clarke which are not thicker than 4,5 mm according to Breslaw.

Adolescent↗
PubMed1995

[An electrophysiological analysis of the processes in the evaluation of successfulness in the choice of behavioral programs].

The magnitude of the N1 and P3 waves of event-related potentials (ERPs) recorded in the dog medial frontal cortex were shown to depend on the behavioural context of separate trials. The most prominent P3 waves occurred in two behavioural situations: 1) when an unexpected non-reward followed previously rewarded conditioned responses, and 2) when an absence of the reward resulted in behavioural type shift in the next trial. The enhancement of the P3 seems to be due to a common factor: the discordance between the CR or its results and the previously developed behavioural trend.

Animals↗