Multiple forms of alkaline and acid phosphatases in rat tissues in the postnatal period

1. A new open-circuit respiratory method was developed to estimate mixed venous PCO2 more rapidly and accurately than is possible with rebreathing techniques. 2. The subject breathes a mixture of CO2 in air from an open circuit. Carbon dioxide is added to the air flowing through the circuit at a rate such that the PCO2 in the inspired and expired gases (recorded continuously with a CO2 analyser) are almost identical. 3. Results from respiratory and cardiac patients showed that equilibrium occurred in less than 10 s. There was good agreement between the tensions of CO2 in the respiratory plateaux and in mixed venous and arterial blood withdrawn during equilibrium. 4. During exercise, the tensions of CO2 of the plateaux and arterial blood at equilibrium also showed good agreement. 5. It is suggested that the new method represents an improvement over rebreathing methods as equilibrium is achieved rapidly before the mixed venous tension rises from recirculation.     

Acid phosphatases in the human testis after prolonged estrogen treatment

The testes of 2 autopsied adult men and 6 subjects, suffering from prostatic carcinoma, were analysed for acid phosphatase activities, Two of the prostatic patients had been receiving estrogen treatment at least for a year and had completely regressed testes. Testes of other subjects contained well-defined tubules with different spermatogenic cells in abundance. The total acid phosphatase activity, assayed in the homogenate, showed a marked reduction in the testes of estrogen-treated subjects. Enzymes were separated by cellulose chromatography or by gel filtration combined with cellulose chromatography. Three activity peaks were resolved by the former and four by the latter technique, when homogenates of the control testes were used. In contrast, two to three strongly reduced activities could be discerned from the testes of estrogen-treated subjects. The specific activity of each enzyme after fractionation was compared between control and regressed testes. No difference was observed in the activities of enzyme I. Enzyme II was markedly reduced in the regressed testes, but was clearly present. Enzymes III and IV were either totally absent or showed a marked reduction in the regressed testes. It is suggested that a correlation exists between the destruction of germ cells, as a consequence of estrogen treatment, and the marked reduction in the activity of enzymes III and IV.     

Genetic complexity, structure, and characterization of highly active bovine intestinal alkaline phosphatases

Mammalian alkaline phosphatases (APs) display 10-100-fold higher kcat values than do bacterial APs. To begin uncovering the critical residues that determine the catalytic efficiency of mammalian APs, we have compared the sequence of two bovine intestinal APs, i.e. a moderately active isozyme (bovine intestinal alkaline phosphatase, bIAP I, approximately 3,000 units/mg) previously cloned in our laboratory, and a highly active isozyme (bIAP II, approximately 8, 000 units/mg) of hitherto unknown sequence. An unprecedented level of complexity was revealed for the bovine AP family of genes during our attempts to clone the bIAP II cDNA from cow intestinal RNAs. We cloned and characterized two novel full-length IAP cDNAs (bIAP III and bIAP IV) and obtained partial sequences for three other IAP cDNAs (bIAP V, VI, and VII). Moreover, we identified and partially cloned a gene coding for a second tissue nonspecific AP (TNAP-2). However, the cDNA for bIAP II, appeared unclonable. The sequence of the entire bIAP II isozyme was determined instead by a classical protein sequencing strategy using trypsin, carboxypeptidase, and endoproteinase Lys-C, Asp-N, and Glu-C digestions, as well as cyanogen bromide cleavage and NH2-terminal sequencing. A chimeric bIAP II cDNA was then constructed by ligating wild-type and mutagenized fragments of bIAP I, III, and IV to build a cDNA encoding the identified bIAP II sequence. Expression and enzymatic characterization of the recombinant bIAP I, II, III, and IV isozymes revealed average kcat values of 1800, 5900, 4200, and 6100 s-1, respectively. Comparison of the bIAP I and bIAP II sequences identified 24 amino acid positions as likely candidates to explain differences in kcat. Site-directed mutagenesis and kinetic studies revealed that a G322D mutation in bIAP II reduced its kcat to 1300 s-1, while the converse mutation, i.e. D322G, in bIAP I increased its kcat to 5800 s-1. Other mutations in bIAP II had no effect on its kinetic properties. Our data clearly indicate that residue 322 is the major determinant of the high catalytic turnover in bovine IAPs. This residue is not directly involved in the mechanism of catalysis but is spatially sufficiently close to the active site to influence substrate positioning and hydrolysis of the phosphoenzyme complex.     

Microstructural changes and kinetics of recrystallisation in a few dual-phase steels

Dual-phase structures were produced in three steels (designated A1, A2 and A3) using two different heat-treatment cycles which incorporate intercritical annealing at a temperature of 750°C. In general, alloy A2 contains the maximum and alloy A1 the minimum volume fraction of martensite, with alloy A3 coming in between. All the cold-rolled alloys show elongated cell-like structures and also some deformation bands. Recrystallisation anneals were carried out at 650°C and 800°C. At the lower recrystallisation temperature of 650°C, the cold-worked ferrite starts to recrystallise, whereas, at the higher temperature of 800°C, re-austenitisation of martensite and recrystallisation of cold-worked ferrite take place simultaneously. During the recrystallisation anneal strain free ferrite grains are found to nucleate at both the deformed ferrite-martensite interfaces as well as inside the deformed ferrite grains. The process of recrystallisation in all three alloys, irrespective of the initial heat-treatment as well as annealing temperature, can be described as an in-situ process. The kinetics of primary recrystallisation of ferrite in the cold-rolled dual-phase steels was analysed from the relevant microhardness data using an Avrami-type relationship. In general, the Avrami plots show straight line segments with two distinct slopes, indicating two different processes during recrystallisation. The activation energies measured from the Arrhenius plots range between 66.88 and 83.6 kJ K mole^?1 which are close to the value 84.02 kJ K mole^?1 for the diffusion of carbon in α-Fe.     

Alkaline phosphatases in tissues and sera of cats

The numbers and widths of bands of alkaline phosphatase (ALP) activity in polyacrylamide gels and the comparison of their electrophoretic mobility to that of a reference substance (Rf value) were found to be reliable aids in the identificaiton of various isoenzymes in in serum and organ extracts from cats. The hepatic isoenzyme was identified in sera of clinically normal adult cats, pregnant cats late in gestation, and cats with common bile duct occlusion. In addition to the hepatic isoenzyme, placental ALP was found late in gestation in sera from queens. Sera from kittens less than 15 weeks of age contained only the osseous ALP isoenzyme.     

Protein phosphatases and the regulation of MAP kinase activity

A family with hereditary factor X deficiency is presented. One member, a 25-year-old man, showed a mild bleeding tendency. His factor X activity (extrinsic: 56%; intrinsic: 55%; Russell's viper venom: 57%) and his level of circulating factor X antigen (55% of normal) were markedly reduced. Analysis of his factor X gene revealed a single point mutation within exon II resulting in the substitution of +25 Gla (GAA) by Lys (AAA). The mutation was determined by gene analysis to be heterozygous in this patient, his mother and one of his brothers. Clotting assays of factor X purified from the plasma of the index patient revealed an activity of 89% of normal upon activation with Russell's viper venom, 77% of normal in the intrinsic and 81% of normal in the extrinsic coagulation pathway. The mutation responsible for the substitution of Lys for Gla+25 was introduced into an expression plasmid containing a wild type factor X cDNA and expressed in a mammalian cell line. Factor X antigen levels in the cell lysates and in the supernatant were identical in the mutant and wild type constructs. The specific activity of the factor X expressed from the mutant construct was 3% compared with the wild type construct. These data demonstrate that the substitution of Lys for Gla+25 results not only in a reduced level of factor X in the affected family members, but also in a substantial loss of specific factor X activity.     

高炉喷吹溶剂若干问题的探讨

基于国内外研究成果，对高炉喷吹熔剂的若干问题进行了分析讨论。喷吹熔剂的作用，主要是可以使铁水的硅含量和硫含量降低，当熔剂和煤粉混喷时，对煤粉还具有助燃，防爆作用，在熔剂选择方面，ＭｇＯ系比ＣａＯ系的喷吹效果好，就熔剂的喷吹方式而言，熔剂与煤混磨、混喷最为理想。     

Retinal projections in cyprinid fishes: a degeneration and radioautographic study

The retinal projections of three species of cyprinid fish (Cyprinus macrolepidotus, Cyprinus carpio, Rutilus rutilus) were examined with Nauta and Fink-Heimer methods following enucleation and with radioautography following intraocular injection of [3H]-L-proline. Optic tract axons cross completely in the optic chiasma and are distributed to the hypothalamus (nucleus opticus hypothalamicus pars magnocellularis), the thalamo-pretectal region (11 distinct primary optic centers), and the tectum opticum (stratum fibrosum et griseum superficiale, stratum griseum centrale and stratum album centrale). No accessory optic tract was found. The experimental studies on visual projection of various teleosts are reviewed and discussed.     

Surgery in congenital heart defects: current developments and a few case examples

Congenital heart surgery includes the palliative treatment and surgical complete repair of cardiac malformations in newborns, children and adolescents. Palliative surgery allows early or long-term survival, depending on the primary malformation and the condition of the patient. Confection of a systemic-to-pulmonary shunt (the modified Blalock-Taussig shunt) allows in general recovery from severe cyanosis and leads to development of the hypoplastic pulmonary vascular tree in newborns with severe pulmonary stenosis. Longterm palliation can be applied to all patients in whom establishment of a biventricular heart can not be realized. The total cavo-pulmonary connection represents one possibility to bypass a single ventricle in these complex cases. Total repair allows the restitution of a completely normal anatomy and physiology after surgery; usually, this type of surgery is followed by a normalization of life expectancy with minimal pharmacotherapy. Preoperative diagnosis of congenital heart disease is reasonably performed by transthoracic echocardiography in the majority of cases. Cardiac catheterism is reserved for complex cases and those in which full hemodynamic evaluation is required for proper planning of surgery. Continuous improvement has been realized in the fields of cardiac anesthesiology and pediatric intensive care during the last decade; hence more and more complex cases have been accepted without any negative effect on the operative mortality. Additionally there has been a number of improvements in surgical and perfusion techniques, thus allowing open heart surgery in newborns with a minimal weight of 2000 g. Intraoperative transesophageal echocardiography is performed routinely and allows the proper control of surgical repair; furthermore this examination may be helpful during the weaning period from the extracorporeal circulation. There is a number of interesting topics that will take importance or will be developed in the near future: the role of interventional cardiology in pediatric patients gains more and more importance. There is a potential for minimally-invasive surgery and the number of potential candidates for heart transplantation may increase, due to the fate of long-term survivors after palliative surgery.     

Neuromuscular patterns and the origin of trophic specialization in fishes

The pattern of muscle electrical activity in the pharyngeal muscles of the mollusc-eating sunfish Lepomis microlophus is highly specialized in comparison with the pattern displayed by most other members of the sunfish family and does not change when different prey are eaten. The closest genealogical relative of this species has the specialized muscle activity pattern for crushing prey when it feeds on snails but uses the primitive sequence of muscle activity during swallowing of other prey. The ability of species that crush snails to use molluscan prey effectively is due primarily to the evolutionary transformation of the neuromuscular program controlling the trophic apparatus.