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V Chu

Publications and source records attributed to V Chu.

42 records · Page 3Linked to original sources
PubMed1991

Quantitative analysis of the accuracy of linear array transrectal ultrasound in measurement of the prostate.

In 61 prostate autopsy specimens, linear array transrectal ultrasound and electronic vernier calipers were used to measure 3 maximal diameters along the longitudinal, anterior-posterior and transverse axes. The results were comparable. We assessed the reliability of empirical formulae, derived from various combinations of these 3 diameters, for the prediction of prostatic volume and weight. Formulae using all 3 diameters were accurate. The combination of longitudinal and anterior-posterior diameters, which was used clinically for prostate measurement, was less accurate.

Anthropometry↗
PubMed1982

The fourth component of human complement treated with amines or chaotropes or frozen-thawed (C4b-like C4): interaction with C4 binding protein and cleavage by C3b/C4b inactivator.

We have shown previously that C4 treated with amines or chaotropes, although uncleaved, exhibits properties that are similar to C4b. Studies by other groups suggest that this C4b-like form of C4 is characterized by the lack of an internal thiolester bond that is present in native C4. We report here that C4 treated with N2H4 or KSCN or frozen-thawed, unlike native C4, forms a complex with C4-binding protein (C4-bp) and is cleaved by C3b/C4b inactivator (I). Fragmentation of C4b-like C4 by I occurs without previous cleavage to C4b and requires the presence of C4-bp. Cleavage of C4b-like C4 proceeds in two steps: a small fragment (16,000 m.w.) is released first, followed by cleavage of the remaining alpha-chain fragment (83,000 m.w.) into polypeptides of 46,000 (C4d) and 32,000 m.w. All fragments, except the 46,000 m.w. fragment, are disulfide-linked to the beta- and/or gamma-chains of C4. Cleavage of C4b-like C4 probably occurs at the same points in the alp a-chain as in C4b; however, C4b-like c4 also contains C4a. Based on the m.w. determinations, the C4a portion of the alpha-chain is present in the 83,000 m.w. fragment, and after the second cleavage, in the 32,000 m.w. fragment of C4b-like C4. These findings suggest the following alignment of alpha-chain fragments: the N-terminal C4a portion is attached to a polypeptide of about 25,000 m.w. (alpha 3), which is followed in the sequence by C4d (alpha 2) (46,000 m.w.) and a small 16,000 m.w. fragment (alpha 4) that forms the C-terminus.

Amines↗
PubMed1981

Synthesis and antimalarial effects of N2-aryl-N4-[(dialkylamino)alkyl]- and N4-aryl-N2-[(dialkylamino)alkyl]-2,4-quinazolinediamines.

A series of N2(and N4)-aryl-N4(and N2)-[(dialkylamino)alkyl]-2,4-quinazolinediamines has been synthesized for antimalarial evaluation. Condensation of the appropriate 2,4-dichloroquinazoline (IV) with the requisite N,N-dialkylalkylenediamine afforded a series of 2-chloro-N-[(dialkylamino)alkyl]-4-quinazolinamines (V) which were condensed with the appropriate arylamine to provide the corresponding N2-aryl-N4-[(dialkylamino)alkyl]-2,4-quinazolinediamines (VI). Hydrolysis of 2,4-dichloroquinazoline to 2-chloro-4-quinazolinol was followed by condensation with the appropriate N,N-dialkylalkylenediamine to give an array of 2-[[(dialkylamino)alkyl]amino]-4-quinazolinols (IXa). Chlorination with phosphorus oxychloride and condensation with a requisite arylamine provided the N2-[(dialkylamino)alkyl]-N4-phenyl-2,4-quinazolinediamines (X). Antimalarial activity was general among the N2-aryl-N4-[(dialkylamino)alkyl]-2,4-quinazolinediamines (VI), while the reverse isomers were of lower activity. Phototoxic liability precluded clinical evaluation of a member of the series.

Animals↗
PubMed1980

Metabolism of orally and intravenously administered purines in rats.

One experiment was conducted in which radioactively labeled purine bases (adenine, guanine, hypoxanthine and xanthine) were individually given intravenously to young adult rats and the recovery of radioactivity in urine and gut, gut content and liver was measured at the end of the next 24 hours. The total recovery of radioactivity from orally and intravenously administered adenine was measured in experiment 2. A third experiment measured the recoveries of radioactivity from oral and intravenous adenine in a wider variety of tissues and organs than in experiment 1. The chemical identities of the urinary end products of the metabolism or orally and intravenously administered adenine were compared in a fourth experiment. When purines were given intravenously, significantly more of the administered radioactivity was recovered in urine from rats given guanine, hypoxanthine or xanthine compared with those given adenine. The greater recoveries of radioactivity in urine were associated with smaller recoveries in tissues. A larger proportion of intravenously compared to orally administered radioactivity from adenine was incorporated into all body tissues, and this was most pronounced in glandular and lymphoid tissues. The primary urinary end product of both orally and intravenously administered adenine was allantoin. The absorption of individual purines from isolated rat gut sacs was evaluated in a fifth experiment. A significant proportion of unaltered adenine crossed the mucosal to serosal barrier of intestinal sacs whereas unaltered guanine, hypoxanthine or xanthine did not cross into the serosal fluid. These results show that the intestinal metabolism of dietary adenine is uniquely different from that of guanine, hypoxanthine or xanthine.

Adenine↗