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1

Melanin synthesis in microorganisms - biotechnological and medical aspects

100%
Plonka P. M., Grabacka M.
Acta Biochimica Polonica
|
2006
|
tom 53
|
nr 3
2

Occurrence of nitric oxide plasmodia of the acellular slime moulds (Myxomycetes)

100%
Rakoczy L., Plonka P. M.
Acta Physiologiae Plantarum
|
1998
|
tom 20
|
nr 1 suppl.
3

Growth of mixed cancer cell population - in silico the size matters

100%
Klos A., Plonka P. M.
Acta Biochimica Polonica
|
2020
|
tom 67
|
nr 4
4

Akumulacja manganu w plazmodiach sluzowca [Myxomycetes] Metatrichia vesparium

100%
Rakoczy K., Plonka P. M.
Ochrona Środowiska i Zasobów Naturalnych
|
2000
|
nr 18
299-308
5

Electron paramagnetic resonance spectroscopy [EPR] as a method for studying the biology of the acellular slime moulds [Myxomycetes]

100%
Plonka P. M., Rakoczy L.
Acta Physiologiae Plantarum
|
1997
|
tom 19
|
nr 2
6

Melanin-like pigment granules in the irradiated plasmodium of the acellular slime mould Physarum nudum

100%
Rakoczy L., Plonka P. M.
Cellular and Molecular Biology Letters
|
2002
|
tom 07
|
nr Suppl.
7

Sclerotia of the acellular [true] slime mould Fuligo septica as a model to study melanization and anabiosis

81%
Krzywda A., Petelenz E., Michalczyk D., Plonka P. M.
Cellular and Molecular Biology Letters
|
2008
|
tom 13
|
nr 1
130-143
Acellular (true) slime moulds (Myxomycetes) are capable of a transition to the stage of sclerotium — a dormant form of plasmodium produced under unfavourable environmental conditions. In this study, sclerotia of Fuligo septica were analyzed by means of electron paramagnetic resonance (EPR) spectroscopy. The moulds were cultivated in vitro on filter paper, fed with oat flour, and kept until the plasmodia began to produce sclerotia. The obtained sclerotia differed in colour from yellow through orange to dark-brown. The EPR spectra revealed a free radical, melanin-like signal correlated with the depth of the colour; it was strongest in the dark sclerotia. Sclerotization only took place when the plasmodia were starved and very slowly dried. Only the yellow sclerotia were able to regenerate into viable plasmodia. This suggests that myxomycete cytoplasm dehydration is an active process regulated metabolically. Plasmodial sclerotization may therefore serve as a convenient model system to study the regulation of cytoplasmatic water balance, and sclerotia as a convenient material for EPR measurements, combining the quality of plasmodia with the technical simplicity of the measurements characteristic of dry spores. Darkening of the sclerotia is most probably a pathological phenomenon connected with the impairment of water balance during sclerotization.
8

Extradermal melanin transfer? Lack of macroscopic spleen melanization in old C57BL-6 mice with de-synchronized hair cycle

81%
Michalczyk D., Popik M., Salwinski A., Plonka P. M.
Acta Biochimica Polonica
|
2009
|
tom 56
|
nr 2
343-353
 In quest of alternate, extradermal path of melanin transfer from skin to the visceral organs, we suggested that some portions of such melanin may be deposited in the spleen, which in young black C57BL/6 mice is often melanized. Here, we confirm these observation using young C57BL/6 female mice (up to 17 weeks) and show that this phenomenon cannot be observed in old animals where the hair cycle is not synchronized any more. The experiments were carried out both on spontaneous and depilation-induced hair cycle. We have checked it as a side-observation over many other experiments carried out on young and old C57BL/6 female mice (up to 2.5 years of life). The presence or absence of melanin in the spleens was checked macroscopically, and histologically by Fontana-Masson (FM) staining, and synchronization of the hair cycle - by standard histomorphometric analysis of the back skin hair follicles. In about 40% of old spleens black FM-stainable "debris" could be found under closer histological examination. This study shows that, at least in part, the phenomenon of splenic melanosis in C57BL/6 mice can be correlated with the synchronized skin melanization parallel to the hair cycle progress, and that splenic melanin undergoes gradual degradation during the mouse life.
9

Kinetics of increased generation of NO in endotoxaemic rats as measured by EPR

80%
Plonka P. M., Chlopicki S., Wisniewska M., Plonka B. K.
Acta Biochimica Polonica
|
2003
|
tom 50
|
nr 3
Ferrous-diethyldithiocarbamate (Fe(DETC)2) chelate is a lipophilic spin trap devel­oped for NO detection by electron paramagnetic resonance (EPR) spectroscopy. Using this spin trap we investigated the kinetics of NO production in endotoxaemia in rats induced by lipopolysaccharide (Escherichia coli, 10 mg/kg). The NO-Fe(DE- TC)2 complex was found to give a characteristic EPR signal, and the amplitude of the 3rd (high-field) component of its hyperfine splitting was used to monitor the level of NO. We found that in blood, kindey, liver, heart and lung NO production starts to in­crease as early as 2 h after LPS injection, reaches the maximum 6 h after LPS injec­tion and then returns to basal level within further 12-18 h. Interestingly, in the eye bulb the maximum of NO production was detected 12 h after LPS, and the signal was still pronounced 24 h after LPS. In brief, the highly lipophilic exogenous spin trap, Fe(DETC)2 is well suited for assessment of NO production in endotoxaemia. We dem­onstrated that the kinetics of increased production of NO in endotoxaemic organs, with the notable exception of the eye, do not follow the known pattern of NOS-2 induc­tion under those conditions. Accordingly, only in early endotoxaemia a high level of NO is detected, while in late endotoxaemia NO detectability is diminished most probably due to concomitant oxidant stress.
10

Splenic melanosis during normal murine C57BL/6 hair cycle and after chemotherapy

71%
Michalczyk-Wetula D., Salwinski A., Popik M., Jakubowska M., Plonka P. M.
Acta Biochimica Polonica
|
2013
|
tom 60
|
nr 3
 Cancer chemotherapy is associated with serious side effects, including temporary hair loss and impairment of pigmentation. We suspect that ectopic melanin deposition occurring due to chemotherapy may add to these effects worsening the already unpleasant symptoms. We associated the ectopic occurrence of follicular melanin after chemotherapy with splenic melanosis - an interesting example of extradermal melanin localization - and we expected an increase in splenic melanin deposition after chemotherapy. Using the C57BL/6 murine model of synchronized hair cycle induced by depilation, we visualized splenic melanin by means of several histological and histochemical protocols of staining: hematoxylin and eosin, May-Grünwald-Giemsa and Fontana-Masson. Unexpectedly, the splenic deposition of melanin decreased due to application of cyclophosphamide (i.p. 120 mg/ kg body weight on day 9 post depilation). The drop was abrupt and lasted for at least 5 days (day 13-18 post depilation), as compared with normal hair cycle. Moreover, in mice with normal, depilation-induced hair cycle we observed a similar drop shortly before entering catagen (day 15 post depilation), followed by a slow and partial increase in splenic melanization up to day 27 post depilation in both groups. We conclude that cyclophosphamide negatively affects splenic melanization and/or extradermal transfer of ectopic melanin from the dystrophic hair follicles, but the most powerful down-regulator of splenic melanosis is normal and dystrophic catagen - the phase of hair follicle involution and re-modelling.
11

X-band and S-band EPR detection of nitric oxide in murine endotoxaemia using spin trapping by ferro-di[N-[dithiocarboxy]sarcosine]

71%
Plonka P. M., Wisniewska M., Chlopicki S., Elas M., Rosen G. M.
Acta Biochimica Polonica
|
2003
|
tom 50
|
nr 3
Ammonium salt of N-(dithiocarboxy)sarcosine (DTCS) chelated to ferrous salt was tested as an NO-metric spin trap at room temperature for ex vivo measurement of NO production in murine endotoxaemia. In a chemically defined in vitro model system EPR triplet signals of NO-Fe(DTCS)2 were observed for as long as 3 hours, only if samples were reduced with sodium dithionite. This procedure was not necessary for the ex vivo detection of NO in endotoxaemic liver homogenates at X-band or in the whole intact organs at S-band, whereas only a weak signal was observed in endotoxaemic lung. These results suggest that in endotoxaemia not only high level of NO, but also the redox properties of liver and lung might determine the formation of complexes of NO with a spin trap. Nevertheless, both S- and X-band EPR spectroscopy is suitable for NO-metry at room temperature using Fe(DTCS)2 as the spin trapping agent. In particular, S-band EPR spectroscopy enables the detection of NO production in a whole organ, such as murine liver.
12

Detection of a pheomelanin-like pigment by EPR spectroscopy in the mycelium of Plenodomus biglobosus

61%
Pukalski J., Marcol N., Wolan N., Plonka P. M., Ryszka P., Kowalski T., Latowski D.
Acta Biochimica Polonica
|
2020
|
tom 67
|
nr 3
13

Splenic aumelanin differs from hair eumelanin in C57BL-6 mice

61%
Plonka P. M., Michalczyk D., Popik M., Handjiski B., Slominski A., Paus R.
Acta Biochimica Polonica
|
2005
|
tom 52
|
nr 2
The presence of melanin in spleens of black C57BL/6 mice has been known for long. Although its origin and biological functions are still obscure, the relation of splenic melanin to the hair follicle and skin pigmentation was suggested. Here, we demonstrated using for the first time electron paramagnetic resonance spectroscopy that black-spotted C57BL/6 spleens contain eumelanin. Its presence here is a “yes or no” phenomenon, as even in the groups which revealed the highest percentage of spots single organs completely devoid of the pigment were found. Percentage of the spotted spleens decreased, however, with the progress of telogen after spontaneously-induced hair growth. The paramagnetic properties of the spleen eumelanin differed from the hair shaft or anagen VI skin melanin. The splenic melanin revealed narrower signal, and its microwave power saturability betrayed more heterogenous population of paramagnetic centres than in the skin or hair shaft pigment. Interestingly, the pigment of dry hair shafts and of the wet tissue of depilated anagen VI skin revealed almost identical properties. The properties of splenic melanin better resembled the synthetic dopa melanin (water suspension, and to a lesser degree – powder sample) than the skin/hair melanin. All these findings may indicate a limited degradation of splenic melanin as compared to the skin/hair pigment. The splenic eumelanin may at least in part originate from the skin melanin phagocyted in catagen by the Langerhans cells or macrophages and transported to the organ.
14

Platelets augment respiratory burst in neutrophils activated by selected species of gram-positive or gram-negative bacteria

51%
Miedzobrodzki J., Panz T., Plonka P. M., Zajac K., Dracz J., Pytel K., Mateuszuk L., Chlopicki S.
Folia Histochemica et Cytobiologica
|
2008
|
tom 46
|
nr 3
383-388
15

Pulmonary metastases of the A549-derived lung adenocarcinoma tumors growing in nude mice. A multiple case study

51%
Jakubowska M., Sniegocka M., Podgorska E., Michalczyk-Wetula D., Urbanska K., Susz A., Fiedor L., Pyka J., Plonka P. M.
Acta Biochimica Polonica
|
2013
|
tom 60
|
nr 3
 Lung adenocarcinoma is a leading human malignancy with fatal prognosis. Ninety percent of the deaths, however, are caused by metastases. The model of subcutaneous tumor xenograft in nude mice was adopted to study the growth of control and photodynamically treated tumors derived from the human A549 lung adenocarcinoma cell line. As a side-result of the primary studies, observations on the metastasis of these tumors to the murine lungs were collected, and reported in the present paper. The metastasizing primary tumors were drained by a prominent number of lymphatic vessels. The metastatic tissue revealed the morphology of well-differentiated or trans-differentiated adenocarcinoma. Further histological and histochemical analyses demonstrated the presence of golden-brown granules in the metastatic tissue, similar to these found in the tumor tissue. In contrast to the primary tumors, the electron paramagnetic resonance spectroscopy revealed no nitric oxide - hemoglobin complexes (a source of intense paramagnetic signals), in the metastases. No metastases were found in other murine organs; however, white infarctions were identified in a single liver. Taken together, the A549-derived tumors growing subcutaneously in nude mice can metastasize and grow on site in the pulmonary tissue. Thus, they can represent an alternative for the model of induced metastatic nodule formation, following intravenous administration of the cancerous cells.
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