Pelvic ring injuries

PURPOSE: Analysis of the trauma patient of fractures of the pelvic ring and classification according to AO/Tile. METHODS: 125 unselected patients (43 females, 82 males) were evaluated retrospectively by conventional x-ray, and CT examinations included follow-studies. RESULTS: Type-A fractures were seen in 36 (29%), Type-B fractures in 58 (46%), and Type-C fractures in 31 (25%) cases. Type-B and Type-C fractures mainly occurred in patients with traffic accidents and falls from great height. Type-A fractures were seen most often in patients with accidents at home or at work. However, in patients with complex fractures a classification concerning Type-B or Type-C fractures was difficult. SUMMARY: Based on CT criterias, in most patients a statement concerning the applied forces, the stability of the pelvic rim and the fracture type can be made.     

Distributed-activation kinetics of

Martensitic nucleation under normal circumstances is a heterogeneous process, and the heterogeneity can be explained by the potency distribution of defects that provide the nucleation sites, including both preexisting and autocatalytically generated defects. The potency distribu- tion of the preexisting defects has been shown earlier by small-particle studies to follow an exponential function, whereas that of the autocatalytic defects is found in the present work to obey a Gaussian function. A major distinction between these two distributions is that the number density of thepreexisting defects increases monotonically with decreasing defect potency, while the number density of theautocatalytic defects is distributed about a mode, giving a saturation level of its cumulative distribution. As a result of these potency distributions, the nucleating sites of both origins exhibit distributions in their activation energies for nucleation, and a distributed- activation kinetic model is now proposed to take these variations into account for martensitic transformations. The features of this model are tested with considerable success in experiments on an Fe-32.3Ni alloy, leading to calculations of the entire course of martensitic transformation curves (including the athermal, anisothermal, and isothermal contributions), the changing shapes of time-temperature-transformation (TTT) diagrams for a range of Fe-Ni compositions, and the grain-size dependence of “bursting” behavior. Formerly Graduate Student, Massachusetts Institute of Technology, is Research Engineer, Bethlehem Steel Corporation, Bethlehem, PA 18016. Formerly Senior Research Associate, Massachusetts Institute of Technology     

Colorectal cell kinetics

The assessment of cell proliferation in colorectal tissue may provide information with both prognostic and therapeutic implications. A variety of methods are available, including flow cytometric estimations of S phase fraction, immunohistochemical and autoradiographic visualization of exogenous and endogenous proliferation proteins, and morphological and stathmokinetic techniques. There is some correlation between Dukes stage and proliferation state features, and there is increased proliferative activity throughout the adenoma-carcinoma sequence. Data on cell proliferation rates are difficult to obtain. When correctly applied, the metaphase arrest technique remains the 'gold standard' of measuring proliferation, but its usefulness in clinical practice is limited. Recent studies have employed dual measurement flow cytometry and double labelling techniques to produce rate data.     

Stabilization of pelvic ring disruptions

Pelvic ring disruptions are challenging management problems for the orthopedic surgeon. Early hemorrhage, permanent nerve injury, and late pain caused by residual pelvic deformity are some of the many complicating factors. A variety of treatment alternatives are available to stabilize the disrupted pelvic ring. Each technique has inherent advantages and problems.     

Injuries of the pelvic ring

The fate of human tumor cells deposited in rat uteri was investigated by light microscopy of histological sections, immunohistochemistry, and scanning electron microscopy of microvascular corrosion casts. The human colonic tumor cell line LS 174 T was used as graft since it can be detected by CEA immunohistochemistry, and spayed nude rats (PVG rnu/rnu) were used as hosts, subjected to different hormonal regimens (no exogenous hormones, medroxyprogesterone acetate, 17-beta-estradiol, or the last two regimens in combination). Intrauterine deposition of a suspension of 2 x 10(6) tumor cells resulted in tumor take in 72% (21/29) of the nude rats. Endometrial growth was verified in only three animals (14%, 3/21). Extraendometrial growth, however, was found in all animals with tumor take. These observations suggest that the endometrium is comparatively resistant to growth of xenografted human colonic tumor cells. The tumor microcirculation consisted of new vessels, giving morphological evidence that tumor growth is dependent on angiogenesis and not on invasion of preexisting vessels.     

MgOHCl thermal decomposition kinetics

Experiments to determine the kinetics of the thermal decomposition of MgOHCl were performed. It was found that the decomposition of MgOHCl commenced at 649 K, and it directly converted into MgO and HCl without undergoing any intermediate step. Decomposition vs time data showed that the thermal decomposition of MgOHCl was a first-order process with respect to the amount of MgOHCl remaining, and the mass transfer of the product HCl gas away from the interface was likely the rate-limiting step. It was also found that the time required to completely decompose MgOHCl into MgO, more than 20 minutes, at the operating temperatures of electrolytic magnesium production processes, 600 °C±50 °C, was significantly longer than the time required, less than 1 minute, to digest the solid magnesium chloride containing feed material into the molten salt electrolyte in these processes. Such delay in the decomposition would mean that any MgOHCl produced during heating and digestion of the feed would not be decomposed by the heat of the electrolyte and thus the persistent MgOHCl would dissolve into the molten salt electrolyte with potentially severe negative consequences on electrolysis cell operation.     

HIDA kinetics in children

We have investigated the immunohistochemical expression of p53, mdm2, p21/waf1 and bcl-2 proteins in 31 thymic epithelial tumours comprising five medullary thymomas (MDT), four mixed thymomas (MT), 12 cortical thymomas (CT), eight predominately cortical thymomas (PCT) and two well-differentiated thymic carcinomas (WDTC). We have found p53, mdm2, p21 and bcl-2 protein expression in 25/31, 8/31, 5/31 and 10/31 thymic epithelial tumours, respectively. Coexpression of p53 and mdm2 proteins was found in eight cases (three CT, four PCT and one WDTC). Five of them were also p21 positive and three p21 negative. Discordant p53+/mdm2-/p21- protein expression was found in 19 cases (three MDT, three MT, nine CT, three PCT and one WDTC). Mdm2 and p21 proteins were not expressed in the absence of p53 protein. Coexpression of bcl-2 and p53 proteins was found in seven cases (three MDT, three MT and one WDTC). Eighteen cases were p53+/bcl-2- (10 CT, seven PCT and one WDTC) and three cases (two MDT and one MT) were bcl-2+/p53-. Our findings indicate that in thymomas, p53 expression is more frequently associated with cortical histotypes while bcl-2 expression is strongly associated with medullary and mixed histotypes. In addition, there is an inverse correlation between p53 and bcl-2 protein expression in thymomas. Coexpression of p53/mdm2/p21 proteins may reflect thymomas with wild-type (wt), p53 gene since mdm2 and p21 proteins are inducible by wt p53 gene. However, in view of previous findings that p53 mutation is an early event in thymomas, the possibility of p53 gene mutation with p53-independent mdm2 and p21 expression should be considered in these cases. Discordant p53+/mdm2-/p21- protein expression may represent thymomas with p53 gene mutations unable to activate expression of mdm2 and p21 proteins.     

Dissolution kinetics of phenylbutazone

This study investigated the possible effects of simultaneous, noninstantaneous, reversible chemical ionization of carbon acids on the dissolution of a typical pharmaceutical carbon acid, phenylbutazone, and its deutero analog. The dissolution rate versus pH profile for phenylbutazone was consistent with phenylbutazone acting as if it were an acid where the ionization can be considered instantaneous. In view of the dissolution behavior of phenylbutazone under various conditions, it is unlikely that the noninstantaneous ionization kinetics demonstrated for this compound play a major role in determining the dissolution rate, either in vitro or in vivo, since the average residence time in a typical aqueous diffusion layer for phenylbutazone dissolution is longer than the reaction time for its ionization. Slowing the reaction time with a primary isotope effect by deuterium substitution for the ionizable proton caused significant deviation from classical behavior for d-phenylbutazone.     

Simulation of the temperature field along the cross-section of a ring during the ring rolling process

This paper presents the approach used to simulate the temperature distribution/progression of a ring with a rectangular cross-section during the ring rolling process. The previously existing 2-D FEM program Finel was used and modifications were made to consider the metal flow in the out-of-plane direction. Simulations were performed for the austenitic steel X6CrNiNb18-10 and the aluminium alloy AA-2219. Each simulation was a combination of multiple, alternating thermal/mechanical and thermal calculations, representing the time the cross-section is in the roll gap and the time it is between the roll gaps. The results from the simulation were compared to preliminary measured values.     

CSP加热炉炉辊辊环的研制

包钢CSP加热炉引自德国.为解决炉辊备件供应和降低维护成本,重点对炉辊辊环的材质、使用性能、制造工艺等进行了综合研究,实现了国产化.经在线两年来实践验证,产品的各项指标均达技术要求并大幅度降低了维护成本.     

Growth kinetics of suspended microbial cells: from single-substrate-controlled growth to mixed-substrate kinetics

Growth kinetics, i.e., the relationship between specific growth rate and the concentration of a substrate, is one of the basic tools in microbiology. However, despite more than half a century of research, many fundamental questions about the validity and application of growth kinetics as observed in the laboratory to environmental growth conditions are still unanswered. For pure cultures growing with single substrates, enormous inconsistencies exist in the growth kinetic data reported. The low quality of experimental data has so far hampered the comparison and validation of the different growth models proposed, and only recently have data collected from nutrient-controlled chemostat cultures allowed us to compare different kinetic models on a statistical basis. The problems are mainly due to (i) the analytical difficulty in measuring substrates at growth-controlling concentrations and (ii) the fact that during a kinetic experiment, particularly in batch systems, microorganisms alter their kinetic properties because of adaptation to the changing environment. For example, for Escherichia coli growing with glucose, a physiological long-term adaptation results in a change in KS for glucose from some 5 mg liter-1 to ca. 30 microg liter-1. The data suggest that a dilemma exists, namely, that either "intrinsic" KS (under substrate-controlled conditions in chemostat culture) or micromax (under substrate-excess conditions in batch culture) can be measured but both cannot be determined at the same time. The above-described conventional growth kinetics derived from single-substrate-controlled laboratory experiments have invariably been used for describing both growth and substrate utilization in ecosystems. However, in nature, microbial cells are exposed to a wide spectrum of potential substrates, many of which they utilize simultaneously (in particular carbon sources). The kinetic data available to date for growth of pure cultures in carbon-controlled continuous culture with defined mixtures of two or more carbon sources (including pollutants) clearly demonstrate that simultaneous utilization results in lowered residual steady-state concentrations of all substrates. This should result in a competitive advantage of a cell capable of mixed-substrate growth because it can grow much faster at low substrate concentrations than one would expect from single-substrate kinetics. Additionally, the relevance of the kinetic principles obtained from defined culture systems with single, mixed, or multicomponent substrates to the kinetics of pollutant degradation as it occurs in the presence of alternative carbon sources in complex environmental systems is discussed. The presented overview indicates that many of the environmentally relevant apects in growth kinetics are still waiting to be discovered, established, and exploited.     

Wessely-type immune ring following phototherapeutic keratectomy

Immune rings following photorefractive keratectomy (PRK) have been reported but have not been described in detail. This case report describes an immune ring after phototherapeutic keratectomy (PTK) in a patient with long-standing superficial corneal scars. A dense white ring formed in the peripheral cornea on the fourth day following surgery. The patient was treated with antibiotics until negative cultures were reported 48 hours later. A biopsy was taken and examined by light microscopy using hematoxylin-eosin and Mason's trichrome staining. The stroma showed focal keratocyte depopulation with nuclear fragments, occasional polymorphonuclear leucocytes, and an active fibroblastic reaction. No lymphocytes or plasma cells were seen. Clinically, the immune ring faded slowly and was still apparent 9 months after the PTK. Studies of similar cases are required to clarify the mechanisms responsible for this phenomenon.     

Malignant lymphomas of the Waldeyers ring

1 The ability of sodium p-benzyl-4-[1-oxo-2-(4-chlorobenzyl)-3-phenylpropyl]phenyl phosphonate (N-0164) to antagonize contractions produced by prostaglandins E2 and F2a on isolated preparations of gerbil, rat and guinea-pig gastrointestinal muscle has been studied. 2 N-0164 was found to be a potent, partially selective prostaglandin antagonist in these isolated smooth muscle preparations. The blockade produced by N-0164 in the isolated stomach strip of the rat had some, but not all, the characteristics of a competitive antagonism. 3 N-0164 produced a dose-dependent decrease in tone in the rat stomach strip that was abolished by pretreatment of the preparation with indomethacin. 4 N-0164 prevented diarrhoea induced by prostaglandin E2 in mice when given by intraperitoneal injection but was less effective when given orally. 5 N-0164 inhibited oedema induced with croton-oil and pyridine-ether in the mouse ear. 6 N-0164 delayed the onset of erythema following ultraviolet irradiation of guinea-pig skin only when an equimolar amount of pralidoxime chloride was added to the vehicle. 7 It is concluded that N-0164 is a potent, partially selective prostaglandin antagonist on several isolated smooth msucle preparations. N-0164 exhibits activity in vivo particularly following local application when problems associated with penetration and distribution are minimized.