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Biomedical subjects

R Roll

Publications and source records attributed to R Roll.

At least 37 records · Page 2Linked to original sources
PubMed1983

Thallium determinations in fetal tissues and maternal brain and kidney.

The transfer of T1+ cations through the placental barrier of pregnant mice and rats was studied by comparing the thallium concentrations in the maternal brain and kidney and those in fetal tissue at times of 10 min to 50 h after dosage of the animals with 10 mg/kg body wt. T1(2)SO4. The quantitative determinations were performed with field desorption mass spectrometry after dilution of the homogenised tissue samples with enriched stable isotopes of thallium. The total sample quantity required for one complete assay is 1-3 micrograms, the analysis time for one determination about 30 min.

Animals↗
PubMed1983

[Comparative studies on the embryotoxicity of 2-methyl-4-chlorophenoxyacetic acid, mecoprop and dichlorprop in NMRI mice].

From the group of herbicidal phenoxy carbonic acids, 2-methyl-4-chlorophenoxyacetic acid (MCPA; 0-500 mg/kg), 2-(4-chloro-2-methyl-phenoxy) propionic acid (mecoprop/MCPP; 0-700 mg/kg) and 2-(2,4-dichlorophenoxy) propionic acid (dichlorprop/2,4-DP; 0-500 mg/kg) as well as the dextrorotatory compounds of MCPP (MCPPD; 0-500 mg/kg) and 2,4-DP (2,4-DPD; 0-500 mg/kg) were studied in NMRI mice after oral administration between days 6-15 of pregnancy. All five substances proved to be embryotoxic and teratogenic in varying intensity. MCPA proved to be most effective: it was embryotoxic from doses of 100 mg/kg and teratogenic from 200 mg/kg. The remaining compounds (MCPP, MCPPD, 2,4-DP, 2,4-DPD) were embryotoxic from doses of 300 mg/kg and caused malformations of the skeleton from 400 mg/kg. The embryocidal and teratogenic potencies of the dextrorotatory components of MCPA and 2,4-DP exceeded those of the corresponding racemates. Influences of MCPPD and 2,4-DPD upon postimplantative loses, frequency of cleft palates and wavy ribs appeared already at dosages being 100-200 mg/kg below those of the racemates given to the respective groups of experimental animals. Additional alterations of the skeleton were observed which did not occur following administration of the racemic mixtures: deformed centrums of thoracic vertebra and exencephaly.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1981

Effect of sensorimotor cortical ablation on the placing reaction in the standing cat.

The placing reaction in the standing cat permits the analysis of a movement, the placing movement, together with its postural support. It is provoked by one of two moving plates coming into contact with one forelimb. Each limb rests on a platform equipped with strain gauges which permit changes in force exerted by each limb to be recorded. The placing reaction is characterized by two phases, an early isometric phase lasting until the lift-off of the stimulated limb occurs. It is then that a diagonal postural support on one forelimb and the opposite hindlimb takes place so that the placing movement can take place. Performance of this movement corresponds to the second phase. Four cats underwent an unilateral lesion in sensorimotor cortex. Two animals had a large lesion extending to the pre- and post-cruciate regions and from the midline to the coronal sulcus, including a large part within the depth of that sulcus. Two other cats had a restricted lesion covering mainly the forelimb part of area 4. After extensive cortical lesions, permanent changes in the contralateral placing reaction were observed. The isometric phase increased in duration, without marked changes of the pattern of postural support whereas the movement was prolonged and usually hypermetric. On the contrary, ipsilateral placing with its associated postural support was unmodified. After restricted cortical lesions, only temporary changes were observed. Recuperation was complete within 30 postoperative days. It was concluded that motor cortex on one side controls, as a whole, the contralateral placing movement and its associated postural adjustment, whereas it does not significantly modify the ipsilateral placing and its associated postural responses notwithstanding the use of the contralateral limbs in this adjustment.

Animals↗
PubMed1977

[Studies on the embryotoxicity of monolinuron and buturon in NMRI-mice (author's transl)].

The acute LD50 in virginal NMRI-Mice was found to be 2528 mg/kg for monolinuron and 1791 mg/kg for buturon. Pregnant female mice of the NMRI strain were administered orally 25--1000 mg monolinuron/kg (I) and 100-400 mg buturon/kg (II) on days 6--15 of gestation and, during defined phases of fetal development (days 10--13 after conception), 500 mg I/kg and 350 mg II/kg. Following administration of 10 doses, an increase of postimplantative losses and clear retardation of development in the upper dose range from 100 mg I/kg and 300 mg II/kg as well as a dose-dependent increase of the rate of cleft palates could be observed. High doses of both substances given from day 6--15 of pregnancy produced minor numbers of wavy and fused ribs as well as hypoplasia of the upper jaw after application of monolinuron and exenteria and exencephaly after buturon. Administration of monolinuron between days 10 and 13 of gestation resulted a minor and that of buturon a clear increase of the number of cleft palates. To evaluate postnatal development 200 and 500 mg I/kg, and 200 and 300 mg II/kg were administered orally on days 6--15 of gestation. In the higher doses, both substances produced an increased mortality among the offspring up to 3 weeks after birth, and a clear increase of the rate of cleft palates.

Abnormalities, Drug-Induced↗
PubMed1975

[Letter: Herbicides].

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2,4-Dichlorophenoxyacetic Acid↗