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Several letters to the editor are presented in response to articles in previous issues including an article related to the quality of political leaders in Australia, an article related to Americanization of Australian suburbia, and an article related to law enforcement for the Jewish Defense League and for the Black Panther Party.

Fluorescent antibody staining with antibodies to the f and g locus allotype markers present on rabbit α-chains revealed that the α-chain is the heavy chain on the Peyer's patch lymphocytes which previously had been shown to be the precursors of IgA-producing plasma cells. In addition, lymphocytes which had been stripped of membrane Ig with pronase and then cultured overnight to allow the sole expression of endogenous membrane Ig were found to have either the µ-chain or the α-chain on their membranes, but not both. These results suggest that most lymphocytes are restricted to the synthesis of one class of heavy chains at a time and that the commitment to synthesizing that particular heavy chain is maintained during the differentiation of lymphocytes into plasma cells. The proportion of lymphocytes with membrane α-chains is higher in the Peyer's patch and appendix, two gut-associated lymphoid tissues (GALT), than in other lymphoid tissues. Since the GALT are enriched sources of precursors for IgA-producing plasma cells compared to nongut-associated tissues, the presence of cells bearing membrane α-chains correlates well with the relative abilities of these tissues to generate IgA plasma cells.

A total of 36 samples of urine collected during the estrous cycle were analyzed for 5β-pregnan-3α, 6α-diol-20-one and an incompletely identified steroid designated as solvolysis X. Sequential β-glucuronidase and solvolysis treatment were used to cleave conjugates prior to extraction. The metabolites were measured by gas-liquid chromatography. The concentration of each metabolite in urine was significantly (P<.01) lower at estrus and 19 to 21 days after estrus as compared with 13 to 15 days after estrus. The identified metabolite, 5β-pregnan-3α, 6α-diol-20-one was combined with levels observed for three other metabolites of progesterone as previously published and compared with levels of progesterone in ovarian venous blood plasma. The changes in concentration of these metabolites in urine mimicked the changes in concentration of progesterone in ovarian venous blood plasma. Preliminary data indicate that steroid content in urine may be expressed as a ratio to urinary creatinine to estimate excretion rate.

Urine excreted following intravenous administration of 9 µc. representing 166 mcg. of progesterone-4-14C to one sow on day 13 and day 19 of the estrous cycle was used to evaluate extraction procedures and to characterize the steroid compounds containing 14C. Approximately 80% of the radioactivity in urine was rendered extractable by sequential treatment with β-glucuronidase enzyme and solvolysis. An additional 17% was extracted after treatment of the latter aqueous residue with acid which indicates the presence of conjugates other than simple glucuronides or sulfates.A major portion of the extracted radioactivity was in the neutral fraction (89%) as compared with 6.6% in the acid+phenolic and 4.3% in the petroleum ether-benzene phenolic fractions. Four major metabolites of progesterone-4-14C, previously identified, account for 80 to 90% of the radioactivity in the neutral fraction. Four other unidentified 14C metabolites were isolated but these represent only a small portion of the metabolites of progesterone in sow urine.

Urinary pregnanediol (3 α, 20 a-dihydroxy- 5 β-pregnane) and the 3 β 5 a and 3 α 5 β isomers of pregnanolone (3-hydroxy-5-preg-nane-20-one) were quantitatively measured and unadjusted for method losses in 40 samples of urine from 10 cycling sows. These compounds were significantly lower for 0, 1 to 3 and. 19 to 21 days after estrus than the period 4 to 18 days after estrus. Urinary concentration of the metabolites was highest 10 to 15 days after estrus. The excretion pattern of these progesterone metabolites throughout the estrous cycle approximated the levels of progesterone adjusted for method losses in ovarian venous blood samples taken the day urine was collected. Pregnanediol concentration was significantly (P<.01) correlated with 3 β 5 α (0.47) and with 3 a 5 β pregnanolones (0.84). The correlation between 3 β 5 α and 3 α 5 β pregnanolones was 0.51 (P<.01). The 3 α 5 β pregnanolone concentration was significantly (P<.05) higher than pregnanediol. The averages were 0.77±0.11, 0.360.07, 0.22±0.04 and 0.79±0.17 mcg./ ml. for concentrations of progesterone in ovarian venous blood plasma, urinary pregnanediol and the 3 β 5 α and 3 α 5 β pregnanolones, respectively.