Correlation of rat hepatic phenylalanine hydroxylase, with tetrahydrobiopterin and GTP concentrations.

Hepatic phenylalanine hydroxylase is reported to be more abundant in experimentally-diabetic rats; whereas livers of animals fed a high protein diet, where gluconeogenesis also prevails, have normal amounts of this enzyme. In this study, in addition to seeking an explanation for this effect of experimental diabetes, we also examined the effects of providing alternative dietary gluconeogenic substrates. In rats fed a diet composed of 40% (w/w) glycerol, the specific activities of hepatic phenylalanine hydroxylase are decreased to about 60% of control values. There is no effect on the apparent state of phosphorylation of the enzyme. However, studies on the incorporation of radiolabelled leucine into liver phenylalanine hydroxylase suggested that there was a decreased rate of synthesis. Similarly, animals fed a diet containing 85% (w/w) fructose also have diminished phenylalanine hydroxylase activities. Under all of the above circumstances and also in streptozotocin-induced diabetic animals, alterations in the concentrations of the hydroxylase cofactor, tetrahydrobiopterin and of GTP closely correlate with the effects on the enzyme activities. They are elevated in livers of diabetic animals and significantly diminished in livers of rats fed diets rich in glycerol or fructose. These observations suggest that in adult rat both liver tetrahydrobiopterin concentrations and the expression of hepatic phenylalanine hydroxylase are regulated by GTP [210].

Technical note: detection and quantification of supplemental fungal beta-glucanase activity in animal feed.

Selected hydrolytic enzymes are added to animal feeds in order to degrade specific antinutritional factors and(or) to increase availability of certain components of feedstuffs to the animal. A method is described that allows detection and quantification of beta-glucanase activity in complex feedstuffs. The method is based on radial diffusion of an enzyme-containing feed extract through an agar gel in which lichenan substrate (a relatively inexpensive glucan of mixed beta 1-->4 and beta 1-->3 linkages) has been dissolved. A linear relationship between the diameter of the zone of substrate hydrolyzed and the log of enzyme activity present was observed. The assay described is technically straightforward and requires no specialized equipment. At typical commercial inclusion levels (1 kg/t), the activity of a supplemental beta-glucanase, added to feed in a commercial mill was determined by averaging several measurements, with a precision of +/- 4%, variation between individual readings of +/- 11.3% (SD), and recovery of 109%. By using high-concentration feed extracts, the method was sensitive enough to detect background and(or) supplemental beta-glucanase activities as low as .05 kg/t supplement equivalent. This method allows consumers, producers, and regulatory authorities to measure the activity of beta-glucanase in feed at commercial inclusion levels and, hence, study the effects of processes such as pelleting and extrusion on such supplements.

An ultrafiltration method for the removal of interfering agents and its application to the determination of free ammonia in solutions of oxystarch by the Berthelot reaction method.

Oxystarch was chosen as a model compound for studying biological ammonia-sequestering systems. Ammonia was determined by use of an ion-selective electrode, by L-glutamate dehydrogenase (L-GDH), and by two different Berthelot procedures, in the presence and absence of oxystarch. In the presence of total oxystarch the Berthelot method, particularly when low concentration reagents were used, detected significantly less (P < 0.10) free ammonia than either L-GDH or ion-selective electrode methods. A 0.5-kDa molecular weight cutoff sample ultrafiltration step was added prior to analysis by L-GDH and Berthelot procedures. To facilitate complete removal of oxystarch by the ultrafiltration step, oxystarch was dialyzed before use, yielding a high-molecular-weight fraction (> 1 kDa). Removal of high-molecular-weight oxystarch species and bound ammonia by ultrafiltration of samples prior to assay completely negated discrepancies between ammonia levels measured by L-GDH and both Berthelot methods. The correlation of the levels of measured ammonia, as determined by L-GDH and Berthelot methods, in mixtures with high-molecular-weight oxystarch was significantly improved by the addition of the sample ultrafiltration step. Improved correlation of results from such fundamentally different methods demonstrates the removal of interfering agents as well as the nonperturbatory nature of the improved procedure. The addition of such an ultrafiltration step may be applied to the determination of ammonia by the otherwise interference-prone Berthelot assay in mixtures with any interfering macromolecules, without the inconvenience or potential variabilities associated with distillation or diffusion procedures.

Enzymes in the animal-feed industry.

The increasing economic pressures currently being placed upon animal producers demand more-efficient utilization of low-grade feedstuffs. In addition, consumer awareness and new legislation require that any increase in animal production cannot be achieved via growth-promoting drugs or other chemical substances. One increasingly popular approach to this problem is to supplement animal diets with hydrolytic enzymes in an attempt to aid the digestion and absorption of poorly available nutrients, or to remove antinutritional factors from the diet. Concerns raised by this practice include the ability of such enzymes to survive processing temperatures and even the animals' digestive tract.

The early diagnosis of breast cancer--a twenty-year experience at the Royal Marsden Hospital.

Over 30,000 women with minimal symptoms were examined between 1968 and 1987 for the detection of early stage breast cancer. Subsequent follow-up screening was selected for women at higher risk because of family history, previous significant benign breast change (e.g. epitheliosis) and hormone replacement therapy. 552 cases of cancer were diagnosed and the current prevalent detection rate is 8.5 per 1000 women examined. Incident cancer (screen-detected and interval) occurred in 6.2 per 1000 women-years at risk. Of the prevalent cancers, 47% were in early T stages of development (TIS, T0 and T1) and this proportion rose to 70% in the screened group. Survival is stage-dependent but the group has not reached its median survival at 15 years. Actuarial estimates of the percentages surviving at 10 years are 73% in the prevalent group and 80% in the incident group.

Immunoglobulin E anti-Staphylococcus aureus antibodies in atopic patients.

Sera from 56 patient and normal adults were examined to quantitate total immunoglobulin E (IgE) and IgE antibodies to Staphylococcus aureus and Staphylococcus epidermidis. Patients were divided into six groups based on clinical symptoms; a seventh group consisted of normal adults. Anti-S, aureus IgE binding was significantly higher in three groups of patients (those with eczema, those with or without series staphylococcal abscesses, and allergic patients with staphylococcal skin infections) than it was in the control group. Patients with high IgE due to allergies or parasitic infections without staphylococcal infections and patients with low or normal IgE and serious staphylococcal infection showed low levels of binding. The assay measured specific binding of IgE to bacterial antigens.

Adjuvant chemotherapy for breast cancer: side effects and quality of life.

In a trial of postoperative adjuvant chemotherapy women with primary breast cancer and spread to one or more axillary nodes were randomised to receive a six-month course of either the single agent chlorambucil or the five-drug combination of chlorambucil, methotrexate, fluorouracil, vincristine, and adriamycin. On completing the treatment 47 patients were asked to fill in questionnaires at home on the side effects of treatment and its influence on the quality of their life. Side effects including nausea, vomiting, malaise, and alopecia had been severe enough to interfere with their lifestyle in 9 (42%) of the patients who had received the single agent and 19 (79%) of those who had received multiple-drug treatment. Various other side effects were reported by a few patients. Seven (29%) of the patients who had received the multiple-drug schedule voluntarily added that the treatment had been "unbearable" or "could never be gone though again." The proportion of patients who had experienced severe side effects while receiving the treatment was considerable; hence such adjuvant chemotherapy is justifiable only if it will substantially improve a patient's prognosis.