Deposition of colloid particles on protein layers: fibrinogen on mica.

Colloid particle deposition was applied to characterize fibrinogen (Fb) monolayers on mica, which were produced by controlled adsorption under diffusion transport. By adjusting the time of adsorption and the bulk Fb concentration, monolayers of desired surface concentration were obtained. The surface concentration of Fb was determined directly by AFM enumeration of single molecules adsorbed over the substrate surface. It was proven that Fb adsorbed irreversibly on mica both at pH 3.5 and at pH 7.4 with the rate governed by bulk transport. The electrokinetic properties of Fb monolayers produced in this way were studied using the streaming potential method. The dependence of the apparent zeta potential of Fb monolayers was determined as a function of the coverage. It was shown that for pH 3.5 the initial negative zeta potential of the mica substrate was converted to positive for Fb coverage exceeding 0.16. On the other hand, for pH 7.4, the zeta potential of a Fb-covered mica remained negative for the entire coverage range. The charge distribution in Fb monolayers was additionally studied using the colloid deposition method, in which negatively and positively charged polystyrene latex particles (ca. 800 nm in diameter) were used. An anomalous deposition of negative latex particles on substrates exhibiting a negative zeta potential was observed. Results of these experiments were quantitatively interpreted in terms of the fluctuation theory assuming that adsorption sites consisted of two and three Fb molecules, for pH 3.5 and 7.4, respectively. These results suggested that for pH 7.4, the distribution of charge on Fb molecules was heterogeneous, characterized by the presence of positive patches, whereas the average zeta potential was negative, equal to -19 mV. The utility of the colloid deposition method for studying Fb monolayers was further demonstrated in deposition experiments involving positive latex particles. It was shown that for a rather broad range of fibrinogen coverage, both the positive and the negative latex particles can adsorb on surfaces covered by Fb, which behaved, therefore, as superadsorbing surfaces. It was also concluded that the colloid deposition method can be used to determine the Fb bulk concentration for the range inaccessible for other methods.

The effect of polyamidoamine dendrimers on human erythrocyte membrane acetylcholinesterase activity.

Polyamidoamine (PAMAM) dendrimers impact on activity of acetylcholinesterase was studied. It has been shown that dendrimers induce a biphasic effect: depending on their concentrations they increase or decrease enzyme activity. It may be due to two types of interactions: direct--between dendrimers and the enzyme; indirect--via a modification of the physical state of membrane phospholipids affecting the acetylcholinesterase.

Photodynamically induced changes of acetylcholinesterase activity from human erythrocytes.

The light and photodynamic actions on acetylcholinesterase activity from human erythrocytes were studied. After light irradiation (670 nm, semiconducting low power laser) the maximum reaction rate increased from 13.3 to 14.8 mumol per ml packed cells per min for an energy dose 9 J, and above that dose it decreased (10.8 mumol per ml packed cells per min for an energy dose of 15 J). The Michaelis-Menten constant changed in the opposite direction. After irradiation of erythrocyte suspension in the presence of zinc phthalocyanine the reaction rate increased, reaching the maximum for energy dose of 0.75 J (16.85 in comparison to the control value of 14.7 mumol per ml packed cells per min. Similarly, the Michaelis-Menten constant decreased reaching a minimum for an energy dose of 0.75 J (0.04 mM compared to 0.07 mM for control). Incubation of erythrocytes with the dye in the dark increased the reaction rate from 13.3 to 14.7 mumol per ml packed cells per min. Neither the incubation in the dark nor irradiation with laser light caused changes of enzyme activity in the presence of chloroaluminium or metal-free phthalocyanine.

An HIV-1 transgenic rat that develops HIV-related pathology and immunologic dysfunction.

We report, to our knowledge, the first HIV type 1 (HIV-1) transgenic (Tg) rat. Expression of the transgene, consisting of an HIV-1 provirus with a functional deletion of gag and pol, is regulated by the viral long terminal repeat. Spliced and unspliced viral transcripts were expressed in lymph nodes, thymus, liver, kidney, and spleen, suggesting that Tat and Rev are functional. Viral proteins were identified in spleen tissue sections by immunohistochemistry and gp120 was present in splenic macrophages, T and B cells, and in serum. Clinical signs included wasting, mild to severe skin lesions, opaque cataracts, neurological signs, and respiratory difficulty. Histopathology included a selective loss of splenocytes within the periarterial lymphoid sheath, increased apoptosis of endothelial cells and splenocytes, follicular hyperplasia of the spleen, lymphocyte depletion of mesenteric lymph nodes, interstitial pneumonia, psoriatic skin lesions, and neurological, cardiac, and renal pathologies. Immunologically, delayed-type hypersensitivity response to keyhole limpet hemocyanin was diminished. By contrast, Ab titers and proliferative response to recall antigen (keyhole limpet hemocyanin) were normal. The HIV-1 Tg rat thus has many similarities to humans infected with HIV-1 in expression of viral genes, immune-response alterations, and pathologies resulting from infection. The HIV-1 Tg rat may provide a valuable model for some of the pathogenic manifestations of chronic HIV-1 diseases and could be useful in testing therapeutic regimens targeted to stages of viral replication subsequent to proviral integration.

Characterization of a chemokine receptor-related gene in human herpesvirus 8 and its expression in Kaposi's sarcoma.

Human herpesvirus 8 (HHV-8) is a recently discovered, virus that is highly associated with Kaposi's sarcoma (KS) and AIDS-associated body cavity lymphomas, although it is also found in some normal individuals. HHV-8 is related by nucleotide sequence homology to herpesvirus saimiri (HVS), which causes T cell lymphomas in some New World monkeys, and to Epstein-Barr virus (EBV), a human herpesvirus linked etiologically with Burkitt's lymphoma and nasopharyngeal carcinoma. We report that, like HVS but unlike EBV, HHV-8 contains a gene (ORF74) with significant sequence homology to the high-affinity IL-8 receptor, a member of the alpha (CXC) chemokine receptor family of transmembrane G protein-coupled receptors. We also show by reverse transcription PCR that the chemokine receptor-related HHV-8 gene is detectable in some RNA samples from KS tissue, and that its expression varies independently from that of ORF26, a minor capsid protein. The presence of a potential chemokine receptor in HHV-8 and its expression in KS tissue suggests that it may be important in the regulation of viral gene expression and may play a role in the etiology of KS and AIDS-related body cavity lymphomas.

[Coexpression of CD4 and CD8 antigens and the appearance of HLA-DR and CD25 receptors on lymphocytes as markers of immune activation in patients with HIV infection]. / Wspólwystepowanie receptora CD4 i CD8 oraz obecnosc receptorów HLA-DR i CD25 na limfocytach jako wskaznik pobudzenia ukladu immunologicznego u osób zakazonych HIV.

Results of quantitative determinations of peripheral blood lymphocytes presenting CD4 or simultaneously CD4 and CD8 antigens as well as HLA-DR and CD25 antigens in patients with different clinical stages of CD4+ and CD4+CD8+ cells were observed. The fall of CD4+CD8+ lymphocytes percentage was slight in the initial stages of infection but more sharp during the full-blown AIDS. The percentage of HLA-DR positive cells was higher in seropositive patients in comparison with controls and increased with the progression of HIV infection into AIDS. The CD25 expression was also higher in HIV-infected patients, however, it decreased in patients with late stages of AIDS. The observed disturbances could be caused by the direct destruction by replicating HIV or by severe abnormalities of immune system function.

[Difficulties and errors in the diagnosis of retinoblastoma]. / Trudnosci i bledy w rozpoznawaniu siatkówczaka.

The authors analyzed the results of the clinical and histopathological examination of the eyes of 283 children with an initially diagnosed intraocular tumor. In 32 cases (11.4 p.c.) there was no retinoblastoma but a congenital retinal dysplasia, vitreal dysplasia, Leber-Coats disease, chronic inflammatory conditions, or retinopathy of prematurity. Three eyes exhibited rare forms of intraocular tumors. In 4 cases among 283 (1.4 p.c.) the diagnosis was erroneously negative. One suspected the Leber-Coats, Hippel-Lindau disease or posterior uveitis. The pathological examination revealed the presence of retinoblastoma.

[Orbital invasion and recurrence of retinoblastoma]. / Zajecie oczodolu i nawroty w oczodole w przypadkach sitakówczaka.

The authors present a clinical material comprising 94 children (55 boys and 39 girls) with unilateral (28) or bilateral (66) retinoblastoma. The period of observation amounted 5 to 15 years. In 84 children they found advanced changes responding to the fifth grade of the Reese-Ellsworth classification. In 14 cases the tumor expanded behind the eye ball or there was its recurrence. From this group 11 children (78.6%) died. The treatment consisted on application of plates with 60Co, xenon photocoagulation, enucleation, exenteration of the orbit, secondary irradiation of the orbit. The risk factors of the incidence of the orbital changes are discussed.

[Agrammatism in a patient with a lesion of the left temporal lobe. A case report]. / Cechy agramatyzmu u osoby z uszkodzeniem lewego plata skroniowego. Opis przypadku.

A case of aphasia following left temporal lobe lesions is reported. The studied material was collected in a number of various tests including constructing of sentences and longer oral and written texts. A neurolioguistic analysis made possible an insight into the nature of the speech system in this case and characterization of disturbances in morphological aspects and their effect on syntaxis and coherent language. The observation lasting 4 years permitted an evaluation of changes taking place in language recovery during that time period.