Biopterin derivatives in human body fluids and tissues

Levels of biopterin derivatives in urine, serum, milk, cerebrospinal fluid, brain, and liver have been measured with the Crithidia fasciculata assay. Normal levels in serum and urine have been given and compared with those in a number of benign and malignant proliferative disorders, phenylketonuria, kidney disease, Parkinson's disease, schizophrenia, controlled epilepsy, rheumatoid arthritis, and pernicious anaemia. The active component of Crithidia factor in serum was 7,8-dihydrobiopterin. Tissue, urine, and some serum samples contained two active materials, the principal one being 7,8-dihydrobiopterin; a minor constituent was probably tetrahydrobiopterin. Serum biopterin levels following methotrexate administration were raised and subsequent administration of folic acid and 5-formyltetrahydrofolic acid further increased serum levels of biopterin derivatives; this was in contrast to the total absence of response to oral folates without prior methotrexate and to 5-methyltetrahydrofolic acid either with or without methotrexate being given.     

Fine structural observations of sperm resorption in the seminal vesicle of a marine snail, Littorina scutulata (Gould, 1849)

The fine structure of the spermatogonium, spermatocyte and spermatid of a marine snail, Littorina sitkana is described. The ring centriole (annulus) is formed from the distal centriole and it migrates to the base of the mitochondrial region where it lies in a joint-like structure which is formed by an area of invaginated plasma membrane. The distal and proximal centrioles are at first perpendicular to each other but the proximal centriole rotates to a position coaxial with the distal centriole and fuses with it. The peripheral doublet fibers are continuous between the two centrioles but the central fibers originate only in the distal centriole. The acrosome differentiates from the proacrosomal granule which is derived from a Golgi body. Microtubules, present at this stage, may assist acrosomal formation. Chromatin condensation begins with the formation of fibrous strands, then to lamellar plates which become folded and later twisted around the flagellar shaft. In the final stages the lamellae appear in cross section as concentric rings which eventually fuse to form a homogeneously dense nuclear tube.     

Isolated tear of the anterior cruciate ligament: 5-year follow-up study

During the period 1967 to 1971, 64 cadets at the United States Military Academy, West Point, New York, had surgical repair for isolated tear of the anterior cruciate ligament. In a 5-year follow-up study to determine the functional impairment, present disability, and reinjury to the knee, 32 of the 64 patients were located and evaluated by radiographic examination and either by interview or by questionnaire. Twenty-two were commissioned to full duty. 23 had attended ranger or airborne school, and 16 had been in combat. Impairment of ordinary activities was noted by 12 and impairment of athletic endeavors by 24; pain by 71%; swelling by 66%; stiffness by 71%; and instability by 94%. Seventeen of the 32 had had a significant reinjury after the repair of the anterior cruciate ligament. Clinically, we can diagnose the isolated tear of the anterior cruciate ligament by four essential ingredients--a pop at time of injury, inability to continue participation, gross swelling of knee, and maximal swelling within 12 hr. The mechanism of injury is usually deceleration and change of direction, not contact with another player. The follow-up study on this small series indicates that the patients have progressive deterioration of the knee.     

Renaturation of formyltetrahydrofolate synthetase from urea and guanidinium chloride solutions

Formyltetrahydrofolate synthetase from Clostridium cylindrosporum and Clostridium acidi-urici was denatured in 6 M urea and 4 M guanidinium chloride. Viscometric, fluorimetric and ultracentrifugal measurements were used to determine that the protein is completely unfolded under these conditions. The polypeptide chains refold upon dilution of the denaturant-protein solutions to give final concentrations of 0.5 M urea or 0.1 M guanidinium chloride. In the presence of NH4+, but not in its absence, the refolded proteins associate to produce the catalytically active tetramer. Refolding and reassociation were followed by measuring changes in protein fluorescence and by determination of sedimentation constants. Under most conditions 80% of the enzymic activity is recovered.     

Dental management of patients irradiated for oral cancer

Management of patients irradiated for oral cancer should include consideration of their oral health prior to, and after, radiation therapy. Data from 130 patients, followed for a period of 1 to 10 years, are presented and evaluated. The philosophy of retention and maintenance of as many teeth as possible is supported by this data. Extraction of teeth with severe periodontal disease after irradiation also proves to be a relatively safe operation. Osteoradionecrosis tends to be limited in extent and is generally well tolerated by the patient when treated conservatively. A treatment regimen is presented that significantly reduces the morbidity from therapeutic irradiation of the jaws. A comprehensive dental evaluation and follow-up plan coupled with patient cooperation are instrumental to the success of this program.     

Regulation of nitrogen catabolic enzymes in chick liver -- effects of amino acids

It is well-known that in the chick, dietary protein increases the levels of several hepatic enzymes that are involved in nitrogen metabolism and excretion. However, the biochemical mechanism of this response is essentially unknown. The experiments presented in this paper show that the chick is responding to alpha-amino nitrogen and not to any specific amino acid. Furthermore, it is shown that this system responds to endogenous sources of nitrogen as well as dietary protein and that the xanthine dehydrogenase response involves regulation of enzyme synthesis without changing the rate of degradation.     

Effect of the Milwaukee brace on vital and ventilatory capacity of scoliotic patients

The vital capacity (VC) and the maximal voluntary ventilation (MVV) were studied in 29 patients with scoliosis (predominantly idiopathic). The results obtained confirmed earlier observations that scoliotic patients have decreased VC and MVV. The immediate effect of the application of the Milwaukee brace was a slight though statistically significant decrease in MV, whereas there was no significant effect on VC. Treatment with the Milwaukee brace for a mean period of 15 months did not appreciably influence the VC or MVV, as a percentage of the predicted normal values of the patients, when measured without the brace applied.