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Penetration of polydimethylsiloxanes (PDMS) to nervous tissue of rats

Łukasiak J., Jachowska D., Jamrogiewicz Z., Moryś J., Prokopowicz M., Czarnobaj K., Falkiewicz B.

Polimery

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2002

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T. 47, nr 7-8

567-568

EN

Penetration of various forms of PDMS from alimentary tract of rats to their blood, urine and brain has been described. The groups or rats were supplied with PDMS either with food or directly to the stomach (tables 1 and 2). Possibility of organism penetration (espescially nervous tissue) with PDMS using lymphatic path has been proposed.

PL

Opisano przenikanie różnych odmian (PDMS) z przewodu pokarmowego szczurów do ich krwi, moczu i mózgu. Badano grupy szczurów, którym PDMS podawano z pokarmem lub wprowadzano bezpośrednio do żołądka (tabele 1 i 2). Zapropowano możliwość przenikania PDMS do organizmu (w szczególności do tkanki nerwowej) na drodze limfatycznej.

2

Alternatywne mediatory reakcji Mitsunobu

Falkiewicz B., Wiśniewski K., Kołodziejczyk A.S.

Wiadomości Chemiczne

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2001

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[Z] 55, 9-10

849-858

EN

The Mitsunobu reaction is a versatile method for the alkylation of various Bronsted-Lowry acids (HA) by alcohols, proceeding in neutral media in a presence of the redox system which traditionally consists of diethyl azodicarboxylate and triphenylphosphine. The key step of the process proceeds according to the SN2 mechanism and results in one of the most useful attributes of the reaction, namely complete configurational inversion at the carbinol carbon. The reaction, however, has a serious limitation - the acidic component has to have pKa smaller than 13 for the reaction to proceed smoothly. Moreover, the classical methodology of the reaction suffers from low yields when applied to secondary alcohols. In recent years, in order to overcome these drawbacks and expand the versatility of the original combination of the Mitsunobu mediators, significant progress in the reaction methodology has been made, mainly due to the work of Tsunoda and Itô. Two types of new mediators have been developed to replace the azodicarboxylate-TPP system. The first one is an N,N,N',N'-tetrasubstituted azodicarboxamide - tributyl phosphine system. All azodicarboxamide derivatives were found to be more efficient than traditional DEAD in the Mitsunobu reaction, especially for less acidic HX. N,N,N',N'-Tetramethylazodicarboxamide, TMAD, gives the best overall results among acyclic amides, whereas 4,7-dimethyl-3,5,7-hexahydro-1,2,4,7-tetraazocin-3,8-dion, DHTD, in combination with TBP was found to be unique in mediating the formation of the C-C bond with sec-alcohols at room temperature. The other type of new mediators in the Mitsunobu reaction, structurally based on betaine, is cyanomethylenetrialkylphosphorane. The phosphorane reagents are generally less active at room temperature, but in higher temperatures they are, esp. CMMP, better than DHTD-TBP and afford satisfactory alkylation of secondary alcohols. Furthermore, the phosphorane reagents mediate the reaction of acids of pKa up to 23.5 [33]. Comparative studies of the C-alkylation revealed the general reactivity of new mediators as TMAD-TBP ( DHTD-TBP ( CMBP ( CMMP.

3

Absorption and distribution of orally administered siloxanes in rat organs

Łukasiak J., Jamrógiewicz Z., Jachowska D., Czarnowski W., Hrabowska M., Prokopowicz M., Falkiewicz B.

Polimery

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2001

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T. 46, nr 7-8

546-548

EN

Male "Wistar" rats, each ca. 200 g, were fed, each ca. 50 g/day, with (z) a 95% of granulated LSM + 5% of OM-300 polydimethylsi-loxane (PDMS) oil (viscosity about 300 cSt) fodder and (z'z) a (95:5 w/w) LSM - polydimethylcyclosiloxane (cPDMS) oil {i.e., a (1:1) hexamethyltri-cyclosiloxane (D3) - octamethyltetracyclosiloxane (D4) mixture) fodder. Absorption from the alimentary tract and distribution of siloxanes in blood, brain, kidneys, liver and spleen was studied over a 24-hour period in the animals given the first lot of fodder and killed by one in 1, 5 and 24 h. Accumulation and toxic effects of siloxanes were studied in blood, brain, kidneys, liver and spleen in the animals killed after 12 days (Table 1). Silicones were extracted with CC14 and determined by recording 'H NMR spectra on a Tesla Brno BS-587A 80-MHz spectrometer. In groups (z) and (ii), the mean siloxane concentrations in the blood after 12 days were 26š14 and 70+97 |ug/mL, resp. In the specific organs, siloxanes differed only insignificantly between group (z) and (z'z), except for brain where group (z) exceeded group (z'z). In two rats, one given (a) LSM + 1 g OM-300 and the other given (b) LSM + 1 g cPDMS, the 24 h urine and feces contained (a) 300 |ag and 800 mg silicones, resp., and (b) 10-30 fig and 400 mg, resp. PDMS are preferentially absorbed by the brain and kidneys; cPDMS remain in the circulatory system and partly in kidneys. The internal organs showed no pathological changes attributable to siloxanes.

PL

Szczury "Wistar" (każdy o ciężarze ok. 200 g) żywiono dzienną dawką ok. 50 g paszy zawierającej bądź 95% granulatu ŁSM i 5% oleju polidimetylosiloksanowego (PDMS) o lepkości ok. 300 cSt (pasza A), bądź też 95% LSM i 5% oleju polidimetylocyklosiloksanowego (cPDMS) stanowiącego mieszaninę heksametylotricyklosiloksan:oktametylotetracyklosiloksan = 50:50 (pasza B). Badano wchłanianie siloksanów z przewodu pokarmowego i ich rozdział w wybranych organach (krew, mózg, nerki, wątroba, śledziona) w okresie 24 h oraz nagromadzenie siloksanów w tych organach po upływie 12 dób (tabela 1). W przypadku pasz A i B średnie stężenia siloksanów w krwi zmierzone po upływie 12 dób wyniosły, odpowiednio, 26+14 i 70š97 mg/ml. W organach wewnętrznych różnice w zawartości siloksanów pomiędzy paszami A i B były statystycznie nieznamienne, z tym że grupa żywiona paszą (A) wykazała większą zawartość PDMS w mózgu. Dwa szczury, jeden (a) żywiony LSM + 1 g OM-300 i drugi (b) żywiony LSM + 1 g cPDMS wykazały w ciągu 24 h w moczu i kale zawartości siloksanów 300 mg oraz 800 mg (a) oraz 10-30 mg i 400 mg (b). Liniowe PDMS są wchłaniane preferencyjnie przez mózg i nerki, a cykliczne cPDMS pozostają w krwioobiegu i częściowo gromadzą się w nerkach. Badane organy wewnętrzne nie wykazały żadnych zmian patologicznych, które można by przypisać obecności siloksanów.