Application of a radiotelemetric system to evaluate the performance of enteric coated and plain aspirin tablets

The bioavailability of enteric coated and plain aspirin tablets was studied in four beagle dogs. Blood sampling for enteric coated tablets was planned with the aid of a radiotelemetric system. The release of aspirin from its dosage form was detected by monitoring the change in intestinal pH. Aspirin and salicylic acid levels in plasma obtained from the enteric coated dosage form exhibited familiar concentration versus time absorption profiles. Variation in the plasma concentrations of these two compounds within each dog studied (four runs each) was relatively small when time zero was adjusted to the commencement of tablet dissolution. The plasma levels obtained from plain aspirin (three runs each), however, show atypical absorption. The estimated absolute bioavailability was 0.432 +/- 0.0213 and 0.527 +/- 0.0260 for enteric coated and plain aspirin, respectively. Other pharmacokinetic parameters for these two dosage forms such as the highest observed plasma concentration (Cmax) (10.9 +/- 0.535 microgram/mL versus 13.6 +/- 1.88 micrograms/mL) and the time to reach Cmax (tmax) (26.6 +/- 1.94 min versus 31.0 +/- 7.04 min) agree well. The mean values for gastric emptying time, in vivo coating dissolution time, and in vivo disintegration/dissolution time of the tablet core for enteric coated aspirin are 48.7 +/- 7.23 min, 44.3 +/- 3.80 min, and 34.7 +/- 2.04 min, respectively.     

Identification of secretin diastereoisomers produced during synthesis

The byproducts P-1 and P-2, which were produced during the synthesis of porcine secretin, were isolated in pure form from the crude secretin by HPLC. These were identified by a combination of amino acid analysis, enzymatic digestion, and isocratic or linear gradient reversed-phase (RP)-HPLC. The amino acid compositions of P1 and P2, determined by amino acid analysis after acid hydrolysis, were found to be the same as those of porcine secretin without distinction between L-and D-amino acids. But, HPLC of their digestive fragments with trypsin and alpha-chymotrypsin differed from that of secretin. The fragments, S7-12 of P-1 and S13-21 of P-2 were determined to be different from the corresponding fragments obtained from secretin by HPLC analysis of their digestive fragments. The amino acid composition of each acid hydrolysate, following digestion with D-amino acid oxidase, was found to have less leucine or alanine content than secretin. The HPLC analysis of the fragments from P-1 and P-2 by tryptic and alpha-chymotryptic digestion showed that they are the same as those from synthetic D-Leu10 secretin or D-Ala17 secretin, respectively. Consequently, P-1 and P-2 are concluded to be the secretin diastereoisomers, D-Leu10 and D-Ala17 secretin, respectively.     

Angiomyolipoma of the kidney; report of two cases with a low fat component

We report two cases of unilateral renal angiomyolipoma. In both cases, our preoperative diagnosis was renal cell carcinoma because no low density area compatible with a fatty tissue was noted in the tumors. Histological examination revealed both tumors to be angiomyolipoma mainly composed of myomatous cells and immature fat cells.     

Carbamazepine, diuretics, and hyponatremia: a possible interaction

Although carbamazepine is known to cause hyponatremia, no previous reports have indicated an interaction between carbamazepine and a diuretic. Two patients are described who were treated with this combination and developed symptomatic hyponatremia, which cleared when both drugs were discontinued in one patient and when the diuretic was discontinued in the second patient. The possible mechanisms of action of carbamazepine-induced hyponatremia are discussed.     

Synthesis of a new carrier for immunization: polytuftsin

Sequential poly(Arg-Thr-Lys-Pro) consisting mainly of the repeat of tuftsin Thr-Lys-Pro-Arg was synthesized by condensing the p-nitrophenyl ester of Arg(HCI)-Thr-Lys-(2-CI-Z)-Pro in the presence of HOBt . Two haptenic sequences of the Pre-S region of hepatitis B virus antigen (10–26 and 39–55) were prepared by solid phase and coupled to polytuftsin via glutaraldehyde. The peptides, either free or coupled to polytuftsin, were administrated to mice and the antisera were assayed by ELISA . Coupling the peptides to the polypeptide significantly improved the anti-peptide antibody titer in Freund complete adjuvant or in NaCI 0.9%. Cross-reaction between antibodies induced by the peptides and the native protein was also improved. Polytuftsin alone is very poorly immunogenic.     

Comparison of immune electron microscopy and genome electropherotyping techniques for detection of turkey rotaviruses and rotaviruslike viruses in intestinal contents.

Seventy-nine intestinal contents specimens from 65 turkey flocks were examined for rotavirus and rotaviruslike virus (RVLV) by immune electron microscopy (IEM) and genome electropherotyping. The IEM procedure was slightly more sensitive in detecting these viruses; 7 of 48 specimens (14.6%) positive for virus by IEM were negative by the genome electropherotyping technique. The genome electropherotyping technique more readily differentiated the rotaviruses and RVLVs than did the IEM procedure; 15 of 48 specimens (31%) positive for virus by IEM could not be differentiated into rotavirus of RVLV, whereas only 4 of the 41 specimens (9.7%) positive by genome electropherotyping produced incomplete genome electropherotypes and could not be differentiated. Thirty-one specimens negative by IEM were also negative by genome electropherotyping. Specimens determined to contain only rotavirus by IEM produced only rotavirus genome electropherotypes. Likewise, specimens determined to contain RVLV alone by IEM produced only RVLV genome electropherotypes. Three specimens contained viruses morphologically resembling rotaviruses that were not aggregated by either the anti-turkey rotavirus serum or the anti-turkey RVLV serum and possessed genome electropherotypes distinct from those of the turkey rotavirus and RVLV. These rotaviruses may represent a third, previously unrecognized serogroup of turkey rotaviruses.