The microflora and concentrations of volatile fatty acids in the rumen of cattle fed on single component rations

The composition of the rumen microflora and the volatile fatty acids were examined in cattle free-grazing on grass or stall-fed on hay, grass pellets, oats or dried beet pulp with molasses. Total and viable counts of anaerobic bacteria were highest on the grass feeding, but viable counts as a percentage of total counts were highest when oats or beet pulp with molasses were fed. Counts of cellulolytic bacteria were lowest on these latter 2 diets, and highest on grass or grass pellet diets. Studies of the anaerobic flora showed that the composition in animals fed on grass pellets resembled more that found in animals free-grazing on grass than in those fed on hay. Counts of aerotolerant bacteria were only a small percentage of the total count, but were highest on the hay diet. On this latter diet and on grass-feeding the streptococci (identified as Streptococcus bovis) were predominant, but contrary to expectation, streptococci were found only in small numbers on the oats diet, where coryneform rods were the major type present. Although a period of 4–6 weeks was allowed for the animals to adapt to the feeds, the 2 periods of feeding on oats and dried beet pulp with molasses markedly affected the composition of the rumen flora in the subsequent periods of feeding grass pellets and hay. Ruinen volatile fatty acid analysis showed a propionogenic effect of oats and the highest percentage of butyric acid when beet pulp with molasses was fed. The expected propionogenic effect of grass pellets was not observed.

Some aspects of the control of dehydroepiandrosterone synthesis in the human adrenal gland in vitro

The control of dehydroepiandrosterone (DHA) synthesis in the human adrenal gland was studied by investigating the biosynthesis of its immediate precursor, 17-hydroxypregnenolone (3β,17α-dihydroxy-pregn-5-en-20-one) and the side-chain cleavage. Both conversions take place in the microsomal fraction and there is an obligatory requirement for the co-factor, reduced nicotinamide adenine dinucleotide phosphate (NADPH). Under optimal conditions, 17-hydroxylation is controlled only by the availability of the substrate and the co-factor. By using the same kinetic approach it was observed that the synthesis of DHA is controlled by the availability of substrate and co-factor. However, the reaction was inhibited by the oxidized form (NADP+) and when the ratio of NADP+:NADPH reached 1, the maximum velocity was halved.

Two major metabolites of 17-hydroxypregnenolone, namely DHA and 17-hydroxyprogesterone, are non-competitive inhibitors of the reaction. The inhibition constants are of the magnitude of the tissue concentration of these steroids in the adrenal gland which suggests that non-competitive inhibition takes place in vivo.

Adrenal function in breast cancer: biogenesis of androgens and cortisol by the human adrenal gland in vivo

A variety of 14C and 3H-labelled steroids have been perfused through the human adrenal gland in situ and their metabolic products isolated from adrenal venous blood.

Progesterone, dehydroepiandrosterone and cortisol were isolated after infusion of [3H]pregnenolone; 17α-hydroxyprogesterone, dehydroepiandrosterone and cortisol after infusion of [3H]17α-hydroxypregnenolone and [14C]progesterone; androstenedione and cortisol after infusion of [3H]17α-hydroxyprogesterone and [14C]dehydroepiandrosterone; and 11β-hydroxyandrostenedione after infusion of [3H]androstenedione and [14C]cortisol.

From a consideration of the incorporation of radioactivity into the metabolic products, the3H: 14C ratios and the tissue pool sizes it was concluded that the major biosynthetic pathway to cortisol in the human adrenal glands was: pregnenolone→ 17α-hydroxypregnenolone → cortisol. Progesterone was not an important intermediary.

Androstenedione was mainly formed by way of 17α-hydroxypregnenolone → 17α-hydroxyprogesterone → androstenedione. 11β-Hydroxyandrostenedione was formed mainly from cortisol and only a minor amount came from the hydroxylation of androstenedione.

Some aspects of the measurement of cortisol production in patients with breast cancer

The production rate of cortisol based on both the plasma clearance of the hormone (plasma production rate) and the urinary metabolite method (urinary production rate) was simultaneously measured in early or advanced breast cancer patients and in controls. Higher production of the hormone was observed by both these methods in patients with advanced breast cancer.

There was a significant correlation between the plasma production rate of cortisol and its urinary production based on the specific activities of three urinary metabolites, namely, cortisol, tetrahydrocortisol (THF) and tetrahydrocortisone (THE). However, the values obtained for the urinary production rate differed considerably in about one-third of the patients due to differences in the specific activities of THE and THF. It is postulated that, in some cases, there may be a second precursor of urinary THE and THF which contributes significant amounts to the excretion of these metabolites.

No correlation was found between the cortisol production rate and urinary total 17-hydroxycorticosteroids (17-OHCS).

In-vitro steroidogenesis by an undifferentiated embryonal cell sarcoma of the ovary

Tritiated pregnenolone, 17α-hydroxypregnenolone, progesterone, 17α-hydroxyprogesterone, testosterone and androstenedione were incubated separately with homogenates from an undifferentiated embryonal cell sarcoma obtained from an 11-yr.-old girl. [3H]Pregnenolone and [3H]17α-hydroxypregnenolone were converted to [3H]oestradiol-17β in larger proportion than [3H]progesterone and [3H]17α-hydroxyprogesterone. The steroidogenesis in the sarcoma was very similar to that reported for the theca cells of the human ovarian follicle.

Adrenal function in breast cancer: the distribution of cortisol in patients with early or advanced breast cancer and in normal women

The distribution of cortisol in patients with early or advanced breast cancer and in controls was studied, using a two-compartment model for analysis. The patients with advanced breast cancer had significantly raised pool sizes. There were no significant differences in the ratio of two pools found for patients and controls. This suggests that there are no abnormalities in the transfer processes.

There was a significant correlation between the exit rate from the intravascular pool and the production rate of cortisol, showing that there is no major extrahepatic metabolism of this hormone in both controls and in breast-cancer patients.

Adrenal function in breast cancer: production and metabolic clearance rate of cortisol in patients with early or advanced breast cancer and in normal women

The production rate of cortisol in patients with early or advanced breast cancer was compared with that of controls of comparable age. The miscible pool of this hormone was raised in advanced breast-cancer patients due to a higher production rate. The plasma clearance of cortisol remained unaffected, resulting in a higher titre of cortisol (both total and unbound) in advanced breast-cancer patients. There was no significant difference in the production rate between the early breast-cancer cases and controls.

The binding of cortisol to transcortin was studied in all cases. The amount of unbound cortisol was raised in advanced breast-cancer cases. There was a significant correlation between both total and unbound cortisol and the production rate of this hormone. The latter correlation suggests that there is no abnormality in the hepatic extraction of cortisol in these patients.

The metabolic clearance rate was found to be of the order of the blood flow through the liver when unbound cortisol was used for its estimation, showing that it is the unbound cortisol which is removed by the liver.