Renal hypertrophy in rats with streptozotocin diabetes or after unilateal nephrectomy was studied by sterological techniques. -- After 4 days of diabetes total glomerular volume had increased by 30%, and after 47 days by 43%. Glomerular growth was more pronounced than whole kidney growth during the first 4 days, but subsequently whole kidney growth exceeded glomerular growth. In control rats glomerular volume was 4.9% of total kidney volume; after 4 days of diabetes it was 5.4% and after 47 days 4.1%. -- Proximal tubule length increased from 366 m/kidney in control rats to 447 m/kidney after 47 days of diabetes; tubular luminal diameter increased from 26.8 micrometer to 31.4 micrometer in the same rats. Tubular length and luminal diameter were, however, not increased after 4 days of diabetes. -- In unilaterally nephrectomised rats there was no early rapid glomerular growth. Glomerular fractional volume was 4.9% in controls, 4.4% at four days, and 4.2% at 24 days after nephrectomy. -- The results indicate a disturbed glomerulo-tubular balance in the early phases of diabetic renal hypertrophy.
This paper presents a thorough molecular characterization of ethyl acrylate (EA) and n-butyl
acrylate (nBA) homopolymers made at high temperature (140−180 °C) to high conversions (50−90%) in
xylene isomers without the use of added thermal initiator. Electrospray ionization/Fourier transform
mass spectrometry (ESI/FTMS) analysis shows four dominant chain types formed during high-temperature
polymerization. Chains initiated by β-scission radicals and by xylol radicals that grow and eventually
terminate to form terminally saturated and unsaturated chains. These chain structures suggest the
underlying secondary mechanisms in high-temperature acrylate polymerization include β-scission
(disproportionation) of the carbon-centered tertiary radical that is most likely formed via intramolecular
chain transfer. Additionally, chain transfer to solvent, xylene in this case, also plays an important
mechanistic role. Results from 1D NMR using 13C, 1H, and distortionless enhancement polarization transfer
(DEPT) corroborate the ESI/FTMS results and additionally predict (i) 2 branch points per chain on average
for EA homopolymer with a number-average molecular weight of 4000 and (ii) 1.25 branch points per
chain on average for nBA homopolymer with a number-average molecular weight of 3300. The presence
of branch points indicates propagation of the midchain tertiary radical does occur to significant extent
under the conditions of the experiments. Neither the ESI/FTMS nor NMR results suggest a mechanistic
route by which the acrylates initiate polymerization without added thermal initiator.
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