Mouse unit

Biol.) (Mause-Einheit) mouse unit. Mechanik,/. mechanics, mechsnism. Mechaniker, m. mechanician, mechanisch, a. mechanical, mechanic. — adv. mechsnically. — mechanisches Gemenge, mechanical mixture, mechanisieren, v.t. mechanize. 

At the start, the sample containing 1 xmol of 6 has a toxicity of 230 mouse units. Epimerization to a mixture of Cl (4) and 6 will reduce the toxicity of the sample. At a ratio of 4 1 a )5, the decrease will be about 11-fold, to 21 mouse units. Hydrolysis of the original sample to the corresponding carbamate, GTX3 (5), would increase the toxicity of the sample 6-fold, to 1400 mouse units. Subsequent epimerization of the hydrolysate, 5, to a 4 1 mixture of the carbamates GTX2 (3) and 5 (or hydrolysis of the epimeric sulfamates 4 and 6 to the same mixture of carbamates) would then change the toxicity to 1,120 mouse units. 

The mouse bioassay for PSP, described in its original form by Sommer in 1937 (29), involves i.p. injection of a test solution, typically 1 mL, into a mouse weighing 17-23 g, and observing the time from injection to death. From the death time and mouse weight, the number of mouse units is obtained by reference to a standard table 1 mouse unit is defined as the amount of toxin that will kill a 20-g mouse in 15 min (77). The sensitivity of the mouse population used is calibrated using reference standard saxitoxin (70). In practice, the concentration of the test solution is adjusted to result in death times of approximately 6 min. Once the correct dilution has been established, 5 mice will generally provide a result differing by less than 20% from the true value at the 95% confidence level. The use of this method for the various saxitoxins and indeterminate mixtures of them would appear... 

Mouse Bioassay. The mouse is the traditional animal of choice for detecting biological activity due to STX and TTX. Mice receive an intraperitoneal injection of sample and are observed for symptoms of intoxication, i.e., dypsnea, convulsions, and death. This method is effective for detecting biological activity of STX and TTX in numerous samples. For the standard STX assay, one mouse unit is defined as that quantity of STX injected i.p. in 1 ml solution that will... 

Tissue Culture Assay. Kogure et al. (48) report a novel tissue culture assay for detecting several types of sodium channel blockers. The mouse neuroblastoma cell line ATCC CCL 131 is grown in RPMI 1640 supplemented with 13.5% fetal bovine serum and 100 pg/ml gentamycin, in an atmosphere of 5% C0 95% air at 37 C. Ninety-six well plates are seeded with 1 x 10 cells in 200 pi of medium containing 1 mM ouabain and 0.075 mM veratridine. Veratridine and ouabain cause neuroblastoma cells to round-up and die. In the presence of sodium channel blockers (e.g., TTXs or STXs), the lethal action of veratridine is obviated and cells retain normal morphology and viability. An important feature of this assay is that a positive test for sodium channel blockers results in normal cell viability. Since bacterial extracts can contain cytotoxic components, this assay offers an advantage over tests that use cell death as an endpoint. The minimum detectable level of TTX is approximately 3 nM, or approximately 1/1000 mouse unit. 

Deteimination of palytoxin. A mouse bioassay method proposed by Teh and Gardiner (25) for determination of L. pictor toxin (=palytoxin) was useful in our studies on the palytoxin-containing animals. The toxin amount in mouse units (MU,... 

Neurotoxic shellfish 20 mouse units/100 g shellfish brevetoxin-2 equivalent... 

The first successful method for measuring the amount of PSP in shellfish was published in 1932. The procedure used was a bioassay. The bioassay for PSP was simple. Extracts from shellfish suspected of contamination were fed to mice. The poison was measured in mouse units. A mouse unit was the amount of toxin that would kill a 20 gram mouse in 15 minutes. Crude, but nevertheless effective at telling public health officials when shellfish were too toxic to eat. 

The early work of Sommer and associates established a good mouse assay for the poison in shellfish products which made quantitative work with the poison practical. A mouse unit (NU) was defined as the minimum amount of poison that would kill a 20-gram white mouse in 15 minutes when one ml of an extract of shellfish was injected intraperitoneally. Higher amounts than the minimum kill in shorter time, i.e., death times of 3, 4, 6, and 8 minutes are equivalent to 3.7, 2.5, 1.6, and 1.3 MU, respectively, as illustrated in Figure 1. 

Figure 1. Elution pattern of toxins from Bio-Rex 70 column in C-labeled arginine feeding. (Fr. fraction number cpm counts per minute and MU mouse units)...

Feeding Precursors Amounts of toxins and isolated in mouse units (mu) radioactivity ... 

Bioassay. Toxicity of the materials was measured by the standard mouse bioassay for paralytic shellfish toxins and expressed by mouse unit (MU) as defined by the method (16). For testing the low toxin levels of algal specimens, extracts were treated with a charcoal column prior to injection into mice. 

Mouse bioassay. The digestive glands of shellfish were extracted thrice with acetone at room temperature. After removal of acetone by evaporation, the aqueous suspension was extracted thrice with diethyl ether, the combined ether solution was backwashed twice with small portions of water and evaporated. The residue was suspended in 1% Tween 60 solution and serially diluted suspensions were injected intraperitoneally into mice weighing 17-20 g each. The mice were observed for 24 hr and the minimum amount of toxin required to kill a mouse at 24 hr was defined as one mouse unit (1). 

The first toxic peak(s) from the Bio-gel P-2 run (volume reduced to 1 ml) is passed through a preparative mini column (Sep-pak 18 to separate the toxin(s) from yellowish pigments. The eluant is then subjected to HPLC using a semipreparative column (CN bonded phase 9.4 mm x 25 cm). Fig. 3 illustrates the presence of neosaxitoxin (second last peak) and saxitoxin (last peak). A total of 150 mu (mouse units) was loaded. The profile in Fig. 4 shows only neosaxitoxin (500 mu) is present because only a portion of the first toxic peak(s) from the P-2 run was injected. The bottom profile is that of a standard neosaxitoxin (200 mu). 

Figure 3. HPLC profile of Aphantoxin most toxic peak (left corresponds to saxitoxin) and the major toxic component (second from left corresponds to neosaxitoxin). A total of 150 mouse units were loaded. A mouse unit is equal to the amount of toxin needed to kill a 20 g mouse in 15 min.

Figure 4. HPLC profile of Aphantoxin major peak (top-left 500 mouse units) and neosaxatoxin standard (2A) (bottom-left 200 mouse units).

The severity of illness was related to the number of mussels eaten. It was concluded that ingestion of 12 mouse-units (the minimum dose of toxin to kill a mouse in 48 hours) of this toxin was sufficient to cause a mild form of illness to an adult. With the discovery of DTXl, this level translates to just 32 pg of toxin per person (Yasumoto et al. 1985). The lack of a proper method for detecting toxins in the... 

LD, (ng/kg body weight) and (jjg/mouse unit) are doses of toxins that produced lethality of 99% and 50% of animals, respectively. 1 1 mixture of toxins B and C (stereoisomers)... 

Somewhat slower kinetics for toxin clearance from the circulation were observed in dogs following parenteral [IV, IP, or intramuscular (IM)] exposure to type A toxin (House et al, 1964). Serum toxin persistence was evaluated in mongrel dogs receiving 8,000 to 10,000 mouse units/kg of type A toxin. Peak serum toxin levels were detected 5 h after IP administration (13% of injected dose), 12 h after IM administration (9% of injected dose), and within only 3 min after IV administration (79% of injected dose) (House et al., 1964). The relative clearance kinetics were slower after IM and IP exposure than for IV administration, as serum toxin levels were identical 22 h after injection via all three rounds (approximately 6% of injected dose). Some serum toxin activity could be detected by the mouse lethality assay for 2 to 4 days after parenteral administration. Serum toxin patterns were also evaluated in rhesus monkeys following IV administration of type A toxin (Stookey et al., 1965). Serum toxin levels dropped by about 50% of maximum within 16 to 24 h after IV injection, and previous exposure did not affect toxin clearance rates after the administration of subsequent doses. 

Botulinum toxin is one of several toxins produced by the bacterium Clostridium botulinum. The toxin binds with high affinity to peripheral cholinergic nerve endings, such as those at the neuromuscular junction and in the autonomic nervous system, preventing the release of the neurotransmitter acetylcholine (1). This action at the neuromuscular junction can cause weakness and even paralysis of the muscles supplied by the affected nerves. Sprouting of the terminal nerves eventually results in re-innervation of the muscles and return of function. Doses are measured in mouse units (MU), IMU being the LD50 in Swiss-Webster mice. 

M.E. Mache-Einheit, Mache unit Mause-Einheit, mouse unit... 

In order to be able to compare results, toxin levels are converted to pg STX.2HC1 equivalents. When MBA has been used, a conversion factor of 0.18-0.20 pg STX.2HCl-eq./mouse unit (MU) is normally applied [3]. 

The toxic and lethal doses are not known. In Taiwan, 30 persons became ill following consumption of the ovaries of an unknown species of fish. Subsequent testing of uneaten ovaries revealed toxin levels of 54 mouse units (MU)/g and 287 MU/g of tissue with an estimated intake of no more than... 

DSP toxins were orally administered to suckling mice (4-5 days old) to evaluate their diarrheic effects. OA and DTX-1 induced intestinal fluid accumulation at 0.1 mouse units (MU)/mouse, while DTX-3 was effective aheady at 0.05 MU/mouse (1 MU is the minimum dose necessary to kill at least 2 out of 3 mice in 24 h and corresponds to 4 pg for OA and 3.2 for DTX-1). In other studies, the diarrheic potency of 7-0-acyl esters of OA in suckling mice was similar to that of OA. ... 

G. edulis (1.9 kg, wet weight) collected in Philippines on December 2, 2002, was extracted with MeOH (2 L) thrice, and the extract was filtered through cellulose filter. The filtrate was concentrated by evaporation and partitioned between hexane and aqueous 80% MeOH. The aqueous 80% MeOH layer was concentrated by evaporation and partitioned between aqueous 40% MeOH and CHCI3. The toxicity in the CHCI3 layer was estimated as 150 MU, when the toxicity to mice was expressed in mouse units (MU) one MU temporally denotes the amount of toxin, which kills one male mouse (ddY strain) of 15 g body weight in 24 h. A half of the CHCI3 layer (75 MU) was concentrated by evaporation, and applied to a silica gel column (Wakogel ClOO, 2 x 10 cm Wako, Osaka, Japan). 

Data quoted as mouse units (MU) have been converted to weights, with 1 MU = 10 ng palytoxin [28,47]. ... 

Urinary Mtrogens are expressed as mouse units in 24 hours (one unit equal to 0.2 gemma M estrone.)... 

F. 8. H. stands for folH[Pg.102]

Fig. 1. E)strogen activity during recovery in several women of menstrual age. Time in weeks is represented along the abscissa. The ordinates correspond to the degree of vaginal response (Grades I to IV) or to Urinary Estrogen Excretion expressed in mouse units.

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