四氯偶氮苯在大鼠胆汁中的分泌和代谢

四氯偶氮苯（３,３’,４,４’ｔｅｔｒａｃｈｌｏｒｏａｚｏｂｅｎｚｅｎｅ,ＴＣＡＢ）和四氯氧化偶氮苯（３,３’,４,４’ｔｅｔｒａｃｈｌｏｒｏａｚｏｘｙｂｅｎｚｅｎｅ,ＴＣＡＯＢ）是在合成氯代或二氯代苯胺类除草剂时生成的污染废弃物。此类除草剂经...     

Immune-mediated neurological syndromes in SARS-CoV-2-infected patients

Journal of Neurology - Evidence of immune-mediated neurological syndromes associated with the severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection is limited. We therefore...     

Diet and retarded growth

The diets of 36 children below the third centile for height but with no organic disease were compared with the diets of a control group. In most cases retarded growth was associated with a long-continued deficiency in calorie intake. When the diets were reassessed about a year later the shortfall in calorie intake was significantly reduced. This improvement, which tended to be followed by an increase in the rate of growth in height, might have been due to alteration in the child's circumstances or improvement in the family attitudes and feeding habits or both. Advice given at the clinic is thought to have played a part in bringing these changes about.     

Adult female voxel models of different stature and photon conversion coefficients for radiation protection

This paper describes the construction of three adult female voxel models, two whole-body and one from head to thighs, from computed tomographic data of 3 women of different stature. Voxel models (also called phantoms) are human models based on computed tomographic or magnetic resonance images obtained from high resolution continuous scans of a single individual. The gray-scale data or information content of the medical images are interpreted into tissues (i.e., organs), a process known as segmentation. The phantoms, consisting of millions of volume elements, called voxels, provide a three-dimensional representation of the human body and the spatial form of its constituent organs and structures. They were initially developed for radiation protection purposes to estimate the organ and effective doses and hence the risk to a person or population due to an irradiation. This paper also presents conversion coefficients for idealized geometries of external photon exposures of energies 10 keV-1 MeV for the three female models, calculated with a Monte Carlo code. Until now there were not any published data on conversion coefficients for explicit female voxel models. Such sets of conversion coefficients exist for voxel adult males or for MIRD-type male, female, and hermaphrodite models. Numerical differences of the calculated conversion coefficients for the voxel female models and MIRD-type models can amount up to 60% or more for external exposures and are due to the improved anatomical realism of the voxel models. The size of the model also has an effect on the conversion coefficients, particularly for deeper lying organs and energies below 200 keV. The three separate sets of conversion coefficients allow one to choose the most suitable model according to the size of the individual as well as to study the dosimetric variations due to the size of the model.     

Effect of perchlorate on calcium release in skinned fibres stimulated by ionic substitution and caffeine

We have determined the effects of the perchlorate ion on the contracture of skinned (sarcolemma removed) skeletal muscle fibres, stimulated either by ionic substitution or caffeine. Calcium release was monitored in single cells by measuring the peak height of tension transients. Perchlorate significantly sensitizes fibres to activation by ionic substitution, a manipulation that is thought to trigger calcium release via the normal physiological pathway. Adding 0.8 mM perchlorate to the solutions shifted the curve relating the magnitude of ionic substitution to the level of activation leftward, such that smaller stimuli were needed to produce a contracture of a given height. Perchlorate could also trigger a contracture directly. Exposing fibres to 1.0 mM perchlorate caused contractures averaging 60% of bracketing controls. In contrast to contractures stimulated by ionic substitution, those triggered by caffeine were unaffected by perchlorate. Since caffeine is thought to act directly on the sarcoplasmic reticulum to cause calcium release, these results suggest that perchlorate enhances activation in skinned fibres by interacting with transverse tubular membranes.     

Absorption and pharmacokinetics of large doses of 1-thyroxine in man (author's transl)]

In recent years suppression tests with a single dose of 3 mg 1-thyroxine (T4) and weekly doses of 1 mg T 4 in the treatment of hypothyroidism have been put to clinical trial and the lack of side-effects of such high doses (5 to 15 X daily requirements) was stressed. Hence, it was decided to study the absorption of 1-T-4 from the gastrointestinal tract and its metabolism in euthyroid patients. Doses from 250 to 2500 mug T 4, mixed with 250 muCi 131I-thyroxine were given to 10 patients. After the thyroid had been blocked with perchlorate, the excretion was followed in faeces and urine for 4 to 5 days, the thyroid uptake of 131I was checked and serial blood samples were drawn to follow plasma activity curves. Quantitative analyses of T 4, triiodothyronine (T 3), ETR and TSH were also performed on the plasma samples, whilst paper chromatography of urine samples allowed a further separation of iodide and organic iodine compounds. The results showed a definite rise in plasma T 4 levels after administration of large T 4 doses, with a simultaneous increase in T 3 values. Doses of 2500 mug T 4 temporarily produce abnormally elevated plasma T 4 and ETR values, whilst T 3 increases to the upper limit of the normal range. The relatively moderate reaction of the mentioned parameters following the administration of large T 4 doses can be partly explained by the considerably lower faecal excretion of T 4 with doses of 250 mug T 4 than with high T 4 doses. There is also an intensive binding of T 4 to TBG up to single doses of 1000 mug T 4, which provides an adequate metabolic "buffer" and declines only after saturation of the TBG binding capacity at higher dosage. Moreover, larger doses of T 4 are metabolized quicker than smaller ones. The above-mentioned results allow the following conclusions: 1. Very large single doses of T 4 (2500 to 3000 mug) are less easily absorbed from the gastrointestinal tract than "physiological" doses. 2. The degradation of T 4 at high dosage is quicker than at lower dosage. 3. The intensive binding of T 4 to TBG explains the lack of side effects with large doses of orally-administered T 4. 4. On the basis of the present data single doses of 500 to 1000 mug T 4 can be recommended for therapeutic purposes.     

Comparison of mechanical and electrical activity and interstitial cells of Cajal in urinary bladders from wild-type and W/Wv mice

Background and purpose:

W/W^v and wild-type murine bladders were studied to determine whether the W/W^v phenotype, which causes a reduction in, but not abolition of, tyrosine kinase activity, is a useful tool to study the function of bladder interstitial cells of Cajal (ICC).

Experimental approach:

Immunohistochemistry, tension recordings and microelectrode recordings of membrane potential were performed on wild-type and mutant bladders.

Key results:

Wild-type and W/W^v detrusors contained c-Kit- and vimentin-immunopositive cells in comparable quantities, distribution and morphology. Electrical field stimulation evoked tetrodotoxin-sensitive contractions in wild-type and W/W^v detrusor strips. Atropine reduced wild-type responses by 50% whereas a 25% reduction occurred in W/W^v strips. The atropine-insensitive component was blocked by pyridoxal-5-phosphate-6-azophenyl-2′,4′-disulphonic acid in both tissue types. Wild-type and W/W^v detrusors had similar resting membrane potentials of −48 mV. Spontaneous electrical activity in both tissue types comprised action potentials and unitary potentials. Action potentials were nifedipine-sensitive whereas unitary potentials were not. Excitatory junction potentials were evoked by single pulses in both tissues. These were reduced by atropine in wild-type tissues but not in W/W^v preparations. The atropine-insensitive component was abolished by pyridoxal-5-phosphate-6-azophenyl-2′,4′-disulphonic acid in both preparations.

Conclusions and implications:

Bladders from W/W^v mice contain c-Kit- and vimentin-immunopositive ICC. There are similarities in the electrical and contractile properties of W/W^v and wild-type detrusors. However, significant differences were found in the pharmacology of the responses to neurogenic stimulation with an apparent up-regulation of the purinergic component. These findings indicate that the W/W^v strain may not be the best model to study ICC function in the bladder.