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Thirteen crossbred boars were immunized at 1 mo of age against either testosterone-3-oxime-equine serum albumin (treated boars) or equine serum albumin (control boars) to test the hypothesis that active immunization against testosterone stimulates testicular growth and development in the prepubertal boar. All boars were injected with the appropriate antigen at 2, 3, 4, 5 and 6 mo of age and were slaughtered at 14 mo of age. Active immunization against testosterone resulted in an increase (P<.05) in tritiated-testosterone binding by plasma within 60 d after the primary immunization; the degree of binding decreased by 6 mo but remained elevated (P<.05) relative to controls through 12 mo of age. There was no effect of treatment on body weights through 12 mo of age. Concentrations of testosterone in plasma were higher (P<.05) in testosterone-immunized boars than in controls; this increase was likely due to antibody binding rather than increased testosterone secretion because (1) concentrations of androgen in testicular parenchyma at slaughter were not altered by treatment and (2) plasma concentrations of estrogens were generally not affected by treatment. Concentrations of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were markedly suppressed in testosterone-immunized boars during the time when concentrations of these gonadotropins were high in control boars (>3 mo of age). In spite of suppression of average LH and FSH concentrations, testicular weights, daily sperm production rates and seminal characteristics were similar for the two groups of boars at slaughter. It is concluded that the boar differs from the bull in its response to prepubertal active immunization against testosterone in that testicular size and sperm production rates are not altered, although gonadotropin secretion is reduced. Further research is needed to define better the relationships between plasma gonadotropin concentrations and testicular development in the boar.

Sequential samples of blood were drawn via jugular catheters every 15 min for 24 h from four mares in each of five reproductive states: 1) intact anestrous mares in winter, 2) intact diestrous mares in summer, 3) intact estrous mares in summer, 4) ovariectomized mares in winter and 5) ovariectomized mares in summer. Estrous mares were sampled on d 4 or 5 of estrus and diestrous mares on d 10 or 11 of diestrus. Each sample of plasma was assessed for concentrations of luteinizing hormone (LH) and follicle stimulating hormone (FSH) in two independent radioimmunoassays. A computer program was developed that determined peak hormone concentrations based on 1) assay sensitivity, 2) assay variability and 3) repeatability of peaks in both independent assays. Peaks in LH and FSH were observed for mares in all five reproductive states, except for FSH concentrations in estrous mares. High frequency peaks of short duration were observed only in ovariectomized mares. Low frequency peaks of relatively long duration were observed in both intact and ovariectomized mares in both seasons. With the exception of estrous mares, there was variation among mares in the patterns of LH and(or) FSH within any one group; all estrous mares exhibited high, variable LH concentrations and low, constant FSH concentrations. In general, peaks in both gonadotropins occurred simultaneously. Ovariectomized mares exhibited more (P<.05) peaks/24 h than intact mares for both gonadotropins. Ovariectomized mares also exhibited more (P<.05) FSH peaks/24 h in summer than in winter.

Samples of jugular blood were drawn from each of five stallions every 15 min for 12 h during the summer and winter to determine the short-term fluctuations in plasma concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone. Concentrations of LH and FSH were generally not pulsatile, although one stallion exhibited three distinct pulses in these hormones during the winter. In general, patterns of secretion of all three hormones were similar in both seasons and the number of significant rises in hormonal concentrations did not differ between seasons. Concentrations of LH and FSH were positively correlated (P<.05) for eight of the ten sampling periods, indicating a close relationship between the secretion rates of these two gonadotropins. Testosterone concentrations varied in an episodic manner during the 12-h period, and all stallions exhibited at least one episode of high testosterone secretion regardless of the pattern of LH concentrations. The response in testosterone concentrations to the three LH pulses exhibited by the one stallion in winter was not the same for each pulse. The correlations between a single random sample and mean concentrations over the 12-h period were high (r between .88 and .99) for all three hormones, indicating that a single sample of blood would be representative of overall concentrations. It appears that the stallion differs from males of other domestic species in that concentrations of gonadotropins and testosterone vary in a much less pulsatile manner.

When patients present with problems for which existing devices are not adequate, research is stimulated. However, new methods and devices must improve on the older versions and should not result in variation that is less effective than the original versions. Variants less effective than the originals will be discussed with illustrative examples. Orthoses, prostheses, and pressure-reduction techniques for the diabetic foot will be considered.

Crop production on light‐textured soils is often dependent on the microbial oxidation of sulfur from soil organic matter or S‐amended fertilizers. Because of the recognized influence of some herbicides on microbial activity, we investigated possible effects of herbicides on the oxidation of S. To study the possible relationship between S availability and herbicides, a field of Tifton Is was selected where herbicides had been applied for 3 years to soil on which corn, soybeans, cotton, and peanuts were grown continuously and in rotation. Recommended rates and methods of application were used in applying the chemicals. During the third year, soil samples were collected from the 0 to 15 cm layer of all plots. Samples were amended with elemental S, incubated at 32C, and sulfates were determined at 10‐day intervals. Oxidation of added S proceeded in all samples, and though the accumulation of sulfates was slowed during the first 10 days, never was it completely inhibited. Irrespective of treatment, the added S was completely oxidized to sulfate by the 40th day of incubation. Though the effect was minor, the combinations of herbicides applied to soybeans and peanuts tended to affect sulfofication more than those applied to corn and cotton.

Five lighthorse mares were actively immunized against gonadotropin releasing hormone (GnRH) to determine the relative importance of this hypothalamic hormone in the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Five mares immunized against the conjugation protein served as controls. Mares were initially immunized in November and received secondary immunizations 4 wk later, and then at 6-wk intervals until ovariectomy in June. All mares immunized against GnRH exhibited an increase (p<0.01) in the binding of tritiated GnRH by plasma, an indication that antibodies against this hormone had been elicited. Concentrations of LH, FSH and progesterone in weekly blood samples were lower (p<0.05) in GnRH-immunized mares than in controls after approximately 4 mo of immunization. However, the LH concentrations were affected to a greater degree than were FSH concentrations. All five control mares exhibited normal cycles of estrus and diestrus in spring, whereas no GnRH-immunized mare exhibited cyclic displays of estrus up to ovariectomy. All mares were injected intravenously with a GnRH analog (which cross-reacted < 0.1% with the anti-GnRH antibodies) in May, after all control mares had displayed normal estrous cycles, to characterize the response of LH and FSH in these mares; two days later, the mares were injected with GnRH. The LH response to the analog, which was assessed by net area under the curve, was lower (p<0.01) by approximately 99% in mares immunized against GnRH than in control mares. In contrast, the FSH response to the analog was similar for both groups. The FSH response to GnRH in mares immunized against GnRH was 85% lower than that in control mares (p<0.05), an indication that the antibodies against GnRH did prevent much of the injected GnRH from reaching the pituitary. At ovariectomy, combined ovarian weights of GnRH-immunized mares were 57% lower than those of control mares (p<0.01); numbers offollicles and corpora lutea were also lower (p<0.O1) than those of controls. It was concluded that LHand to some degree FSH secretion, and probably LHproduction, in the mare are dependent upon the bioavailability of GnRH. However, the lack of effect of GnRH-immunization on FSH response to the analog indicates that FSH stores in the pituitary (and perhaps FSH production) are relatively independent of GnRH bioavailability.

Summary.Testes were obtained from 47 1–20-year-old stallions during the natural breeding season. Total testicular testosterone and testosterone/g testis increased with age (P< 0·005), and total testicular testosterone was associated with larger testis size (P< 0·05). Neither testosterone per gram nor per paired testes were related to total Sertoli cell number (P> 0·05), but greater testosterone per paired testes was associated with fewer Sertoli cells per unit of seminiferous tubule length (P< 0·005) or basement membrane area (P< 0·02) and with a higher number of germ cells supported per Sertoli cell (P< 0·05). Although values for testosterone per gram and per paired testes were unrelated (P> 0·10) to sperm production/g testis or to the yield of spermatids/spermatogonium, testosterone per paired testes was positively related to sperm production per paired testes (P< 0·05). It is concluded that intratesticular testosterone increases with age, is related in a positive manner to quantitative rates of sperm production, and can account for some of the differences in sperm production among individual stallions within a single breeding season.

P-Nitroanisole O-demethylation by perfused rat liver based on the spectral properties of the product, p-nitrophenolate, was determined continuously. Rates of p-nitrophenol production in this system were sensitive to inhibition by CO. p-Nitrophenolate production by livers of normal animals was linear for up to 30 minutes; however, rates were only linear for 1 to 2 minutes followed by a steady decline in induced (6-fold) livers from phenobarbital-treated rats. Only a small portion (24%) of this steady decline could be accounted for by the formation of conjugation products. Additionally, infusion of p-nitrophenol (14 micronM) was not associated with a decline in rate. The decline in rate in induced livers was reversed by glucose, suggesting that an intimate relationship may exist between drug and carbohydrate metabolism in the intact liver. Alteration in rates of p-nitroanisole metabolism with various inducing agents of the mixed-function oxidation system (phenobarbital; ethanol) produced parallel changes in rates of hepatic lactate production, most likely reflecting the aciton of p-nitrophenol to uncouple oxidative phosphorylation. The data support the hypothesis that the decline in rate in p-nitroanisole O-demethylation in livers from phenobarbital-treated rats is due to reduced availability of NADPH for mixed-function oxidation.

Sods of coastal bermudagrass and fescue in permanent pastures or in sod‐based rotations did not greatly inhibit nitrification of applied N at 32 C. Nitrification was strongly inhibited by sods in the finer textured soils at 6 C, especially those high in silt content. Though there were differences in nitrification rates among several sources of N, they were not strongly related to cropping practices. There were wide differences among the various N sources in the percent recovery of applied N. The percent recovery at 32 C was always higher in sodded than in cultivated soils, irrespective of source, but at 6 C the effect of cropping practice was inconsistent.