A computer program for enzyme kinetics that combines model discrimination, parameter refinement and sequential experimental design.

A method of model discrimination and parameter estimation in enzyme kinetics is proposed. The experimental design and analysis of the model are carried out simultaneously and the stopping rule for experimentation is deduced by the experimenter when the probabilities a posteriori indicate that one model is clearly superior to the rest. A FORTRAN77 program specifically developed for joint designs is given. The method is very powerful, as indicated by its usefulness in the discrimination between models. For example, it has been successfully applied to three cases of enzyme kinetics (a single-substrate Michaelian reaction with product inhibition, a single-substrate complex reaction and a two-substrate reaction). By using this method the most probable model and the estimates of the parameters can be obtained in one experimental session. The FORTRAN77 program is deposited as Supplementary Publication SUP 50134 (19 pages) at the British Library (Lending Division), Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1986) 233, 5.     

Role of uronic acids present in phytopathogenic fungi as inducers of polygalacturonases during autolysis

The presence of uronic acids in the culture fluid and mycelium of the fungi: Alternaria alternata, Botrytis cinerea, Drechslera halodes, Fusarium culmorum, Fusarium oxysporum, Monilinia fructigena, Mucor mucedo, Rhizopus stolonifer and Trichoderma hamatum was detected and quantified. In these fungi the concentration of uronic acids increased during the growth phase and the maximal concentrations were found at the end of the growth phase or onset of autolysis both in the mycelium as well as in the culture fluid. The uronic acids were metabolized during the first days of autolysis decreasing to constant levels until the end of the autolytic period studied.The variations in the activity of polygalacturonase and polymethylgalacturonase present in the culture fluid were determined at the onset and during autolysis in these fungi. These enzymic activities were found in the culture fluid of these fungi, with exception of M. rouxii, and they showed an increasing activity in the first days of autolysis and later a slight increase or decrease was observed. The presence of uronic acids in these phytopathogenic or saprophytic fungi and the low levels detected during autolysis could be related to the induction of pectic enzymes and the pathogenicity of these fungi.     

H1° histones of normal and cancer human cells

Summary H1° histones were purified by preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis from human lung carcinoma (line DMS79), human hepatoblastoma (HepG2), human adult lung and human adult and fetal liver. The purified human H1° histones were analyzed for their amino acid composition and terminal residues. The comparative analysis of the amino acid compositions of the different human H1° histones showed that: (a) all the H1° preparations have the characteristically high lysine content associated with a low arginine content, which distinguishes outer histones from core histones; (b) H1° is distinguishable from other H1 histones by the presence of methionine and histidine; (c) H1° histones from human adult, fetal and cancer cells are very similar in amino acid composition, and in cancer cells the level of the H1° histone is not inversely related with cell growth rate nor with the expression of the -fetoprotein gene.     

Kinetics of the 5′-nucleotidase and the adenosine deaminase in subcellular fractions of rat brain

Suspensions of rat brain microsomes, synaptosomes, and synaptic vesicles were able to convert adenosine to inosine by means of adenosine deaminase. Isosbestic points of this transformation, at 222, 250 and 281 nm, remained unchanged with time-course. This fact suggests that adenosine deaminase (ADA, E.C. 3.5.4.4) is located on the surface of the vesicles whereas purine nucleoside phosphorylase (PNP, E.C. 2.1.2.4) is located inside the vesicles. Kinetic parameters of the particulate 5-nucleotidase (5N, E.C. 3.1.3.5) and adenosine deaminase were analogous to those of the cytosolic enzymes. These results suggest that soluble and particulate enzymes represent different pools of the same molecular species.     

Heterogeneous localization of some purine enzymes in subcellular fractions of rat brain and cerebellum

The activity of guanine deaminase (GAH, E.C. 3.5.4.3) was lower in rat cerebellum soluble and microsomal fractions than in rat brain subfractions. Adenosine deaminase (ADA, E.C. 3.5.4.4) activity was released in higher proportion than guanine deaminase, purine nucleoside phosphorylase (PNP, E.C. 2.1.2.4), 5-nucleotidase (5N, E.C. 3.1.3.5), and lactate (LDH, E.C. 1.1.1.27) and malate (MDH, E.C. 1.1.1.37) dehydrogenase in press-juices of rat brain. Furthermore, nerve ending-derived fractions (synaptosomes and synaptic vesicles) showed an enrichment of adenosine deaminase and also of 5-nucleotidase. The action of deoxycholate over the subfractions did not increase the activity of either enzyme. The contrary occurred with the remaining enzymes studied. Thus, it is possible that one set of enzymes are located on the surface of the particulate vesicles, whereas another set are located inside these vesicles, suggesting a compartmentation of purine catabolic enzymes in different areas of the central nervous system.     

A comparative study of salivary secretion by parotid and mandibular glands of anaesthetized Capra hircus: effect of pilocarpine

A study was made of basal secretion and the effect of the infusion of pilocarpine on the flow and composition of saliva in the parotid and mandibular glands of the anaesthetized lactating goat. In the parotid gland there was a basal flow (1.6 +/- 0.29 microliter/min) which was not present in the mandibular gland. There is a statistically significant dose-effect relationship between pilocarpine and salivary flow in both glands. Salival composition and its variation with respect to the flow of saliva did not conform to either of the two glands to an exclusive monogastric or ruminant model.     

The Formation of Otoliths in the Frog Rana esculenta. Scanning Electron Microscopic and X-Ray Diffraction Studies

Two crystal forms of calcium carbonate were observed: calcite (utricle) and aragonite (saccule, lagena, endolymphatic sac). The first step in otolith formation is the appearance of organic structures in the macula. The subsequent step is characterized by fast growing primitive crystals with a prismatic habitus that successively transform into adult or mature crystals. With the metamorphosis, the aragonite crystals of the endolymphatic organ show clear signs of erosion that can be related to a process of CaCO₃ mobilization from such deposits.     

Description of Thecavermiculatus andinus n.sp. (Meloidoderidae), a Round Cystoid Nematode from the Andes Mountains of Peru

Thecavermiculatus andinus n.sp. is described and illustrated from Oxalis tuberosa originally collected in the vicinity of Lake Titicaca high in the Andes mountains of southern Peru. This new species differs markedly front the other two species in the genus, especially in having a much greater female vulval-anal distance and annules with lined punctation on most of the female body with a lacelike pattern restricted to the posterior portion, particularly at the vulva and anus which do not protrude. Females are essentially spherical with protruding neck, white to yellowish in color, and can easily be mistaken for potato cyst nematodes. Among the dozen or more known weed and crop host plants are potato and eggplant. In order to accommodate this new species, the genus Thecavermieulatus is emended. A key to the species of this genus is presented.     

Irradiation as an Alternative to Mastectomy for Early Breast Cancer—An Important Consideration Because of Changes in Laws

Between May 1973 and December 1980 there were 76 patients (78 breasts) with clinical stage I or II breast carcinoma treated by biopsy and definitive radiotherapy at Stanford University Medical Center. Local-regional control has been achieved thus far in 76 of 78 cases (97 percent) with a median follow-up time of 26 months. Transient lymphedema of the breast, arm edema and breast fibrosis were the most commonly noted complications. The cosmetic result was analyzed and scored as excellent in 78 percent, satisfactory in 18 percent and unsatisfactory in 4 percent. The three unsatisfactory results occurred in patients in whom severe fibrosis developed as a result of suboptimal radiation techniques. Interdisciplinary cooperation among surgical, medical and radiation oncologists is important. The 97 percent local-regional control and the 96 percent excellent-to-satisfactory results support the use of primary radiotherapy in early stage breast carcinoma.