Differential effects of sulindac on renal hemodynamics and function in the rat

Renal hemodynamics were studied using an electromagnetic perivascular flow sensor in anesthetized rats injected i.v. with vehicle, 5 or 10 mg/kg body weight (b.w.) sulindac. No hemodynamic changes occurred with vehicle (n=6), but mean arterial pressure was significantly decreased (by 15 mmHg) with sulindac (n=12). In the 5 mg/kg b.w. sulindac group (n=7), renal blood flow progressively and significantly increased from 7.88±0.36 to 8.98±0.58 ml/min, except during concomitant intrarenal infusion of 3 mg/kg b.w. per h proadifen (n=7). The pressure limits for efficient and no renal blood flow autoregulation remained unchanged (approx. 100 and 80 mmHg, respectively). In the 10 mg/kg b.w. sulindac group (n=5), renal blood flow did not change but autoregulatory pressure limits were lowered by 10 mmHg 2 h after treatment (P<0.025). Also, Na⁺ retention was marked. Prostanoid excretion in urine was significantly reduced with either dose but basal plasma renin activity was not (about 8 ng/ml per h; n=15). When plasma renin activity was enhanced after a reduction in renal perfusion pressure (n=21), it was decreased from 11.5±1.2 to 7.4±0.2 ng/ml per h only by 10 mg/kg b.w. sulindac (P<0.05; n=6). In conclusion, differential effects of sulindac on renal hemodynamics, Na⁺ excretion and plasma renin activity were demonstrated. Renal hemodynamic changes could be related in part to the cytochrome P-450 arachidonic acid pathway.     

Opticochiasmatic apoplexy

A 26-year-old patient presented with acute chiasmal syndrome. Computerized Tomography and Magnetic Resonance Imaging demonstrated an intrachiasmal hematoma which was evacuated via a right subfrontal approach. Histological examination revealed an arteriovenous malformation. In 21 similar cases in the literature, surgery generally resulted in the improvement of ophthalmological signs. In 3/4 of the cases, histology identified a subjacent lesion (arteriovenous malformation, cavernoma, venous angioma, glioma).     

Hormone formation in the isolated fragment 1-171 of human thyroglobulin involves the couple tyrosine 5 and tyrosine 130.

The 22 kDa fragment (Asn1-Met171) purified from iodine-poor human thyroglobulin (hTg) is capable by itself to synthesize thyroxine at Tyr5, the preferential hormonogenic acceptor site of the protein, after iodination in vitro. To identify the corresponding donor site in this model we studied the fate of the six Tyr residues present in the 22 kDa peptide after in vitro hormone synthesis. Structural studies of the tyrosyl peptides showed that Tyr5 was the only thyroxine-forming site, the other tyrosines (29, 89, 97 and 107) were noniodinated and Tyr130 was recovered in alanine form after CNBH4 treatment of the Tyr130-containing peptide. Taking into account that alanine could arise from aminoreduced pyruvate species, these results showed that in the 22 kDa fragment (1) hormone formation involves the couple Tyr5 (acceptor)-Tyr130 (donor), and (2) dehydroalanine, the resultant product of donor tyrosine after hormone synthesis, has evolved in pyruvoyl form. To test whether Tyr130 could also act as donor in hTg hormone synthesis, the 22 kDa peptide was isolated from hTg iodinated under conditions leading to iodotyrosine formation followed or not by hormone formation and the tyrosyl peptides were analyzed. After hTg iodination and before coupling (i.e. hormone synthesis) only Tyr5 and Tyr130 were recovered in iodotyrosine form; after coupling thyroxine was found at Tyr5 whereas Tyr130 disappeared. Taken together these results, correlated with the previously reported cleavage of hTg chain at Tyr130 occurring during in vivo hormone synthesis, support the theory that the couple Tyr5 (acceptor)-Tyr130 (donor) would be the preferential hormonogenic site in human Tg.     

Mitochondrial DNA variability detected in a single wheat regenerant involves a rare recombination event across a short repeat

The mitochondrial genome of the selfed progeny of a plant regenerated from long-term somatic tissue culture displays specific structural rearrangements characterized by the appearance of novel restriction fragments. A mitochondrial DNA library was constructed from this selfed progeny in the SalI site of cosmid pHC79 and the novel fragments were subsequently studied. They were shown to arise from reciprocal recombination events involving DNA sequences present in the parental plant. The regions of recombination were sequenced and the nucleotide sequences were aligned with those of the presumptive parental fragments. We characterized an imperfect short repeated DNA sequence, 242 bp long, within which a 7-bb DNA repeat could act as a region of recombination. The use of PCR technology allowed us to show that these fragments were present in both parental plants and tissue cultures as low-abundance sequence arrangements.