bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular approaches to the study of renal disease
Authors: SAKAI HIDETO , JINDE KIICHIRO , SUZUKI DAISUKE , YAGAME MITSUNORI , NOMOTO YASUO
Published: April 2007

Summary: Recent developments in cell biology and molecular biology have provided new techniques for molecular studies on renal diseases. the in situ hybridization technique demonstrates the site and the degree of gene expression of various cytokines and regulating proteins associated with the altered function of the glomeruli. It is not known, however, if the expression of these genes is different among various glomerular diseases. the aim of this study was to elucidate the disease specific phenomena in glomerular gene expression. Renal biopsy specimens were obtained from patients with diabetic nephropathy, and IgA nephropathy. the degree of tissue damage as well as the levels of various clinical parameters were matched between these two groups. In situ hybridization of mRNA in renal tissues for transforming growth factor (TGF)‐β, storomelysin (MMP‐3) and tissue inhibitor of metalloproteinase (TIMP‐1) were performed using nonradioactive digoxigenin (DIG)‐labelled oligonucleotide probes. In parallel studies, renal biopsy specimens were stained with monoclonal antibody against advanced glycated end‐products (AGE). the results demonstrated that the distribution of mRNA expression of TGF‐β was similar between these two diseases, but the expression of MMP‐3 and TIMP‐1 was parallel with the degree of tissue damage in patients with IgA nephropathy while it was diminished in patients with an advanced degree of tissue damage due to diabetic nephropathy. Positive staining of renal tissues with anti‐AGE antibody was only observed in patients with diabetic nephropathy. It is concluded that glycation of renal structural proteins might interfere with their metabolism by enzymes and their inhibitors, while a cytokine responsible for mesangial expansion was similarly expressed.
Major histocompatibility complex class II genes in glomerular diseases
Authors: LI PHILIP KAM TAO
Published: April 2007

Summary: The identification of genes within the human major histocompatibility complex (MHC) class II region, which confer susceptibility of immune mediated nephritis can help to understand the immunopathogenesis and inheritance of these diseases. Classically, this is performed using serological typing. the use of DNA technology in genotyping is more specific and would reveal greater polymorphism within this region. the MHC class II studies of IgA nephropathy (IgAN) and Goodpasture's disease are illustrative. We have shown that by the polymerase chain reaction (PCR) using sequence specific oligonucleotide (SSO) probing techniques, there was an increase of human leucocyte antigen (HLA) DQ7 in Caucasian IgAN patients (71%) when compared with controls (27.8%). In a Chinese family of IgAN, all three siblings with IgAN were homozygous for DR12, DQ7, DQα1b. When we examined 79 Chinese IgAN patients, there was an increase in homozygous DQ7 in patients (16.4%) compared with controls (5.7%). There was also a significant increase in frequency of DQA2 U allele in patients with chronic renal failure (66.9%) compared with patients with normal renal function (26.9%). Goodpasture's disease (GPD) was initially reported to be associated with HLA‐DR2. With molecular techniques, it was found that 75.5% of GPD had DR15 (a specificity of DR 2) when compared with controls (31%). the frequency of DR4 was also increased. Nucleotide sequences of these two alleles were identical to those previously published. Compared with derived amino acid sequences of expressed DRβ chains showed that the DRβ chains of DR15 and DR4 shared a six aminoacid motif from positions 26–31. an SSO detected this amino acid motif in 91.8% of GPD patients tested. Thus, this particular motif, which lies on the floor of the antigen binding groove, has a stronger association with GPD than an individual allele, and may be of pathogenetic significance. It is therefore concluded that the study of MHC class II genes is important in the elucidation of the pathogenetic mechanisms and possibly in the prediction of disease severity in glomerulonephritis.
Treatment of peritonitis complicating continuous ambulatory peritoneal dialysis: an Asian perspective
Authors: CHENG IGNATIUS KP
Published: April 2007

Summary: Geographically, socially, economically and culturally, Asia differs from the United States of America and Europe. These differences may affect the delivery of different continuous ambulatory peritoneal dialysis (CAPD) systems, the incidence and nature of CAPD peritonitis and its treatment. From a recent survey, it has been shown that the use of more expensive disconnect systems has yet to gain popularity in many Asian countries due to its increased cost, but may now be justified in the light of recent cost‐effective studies done in the region. In order to compare the incidence, microbiological profile and treatment strategy of CAPD peritonitis among Asian–Pacific countries, a survey was conducted among renal units of the Asian–Pacific Society members collecting retrospective data from 1 July, 1994 to 30 June, 1995. In this ‘cross country’ analysis, no correlation was found between peritonitis rate and the percentage use of disconnect systems. This observation highlights the difficulties in extrapolating data from one unit (e.g. in the United States of America) to another (e.g. in Asia) in order to decide if one CAPD system is more cost‐effective than the other. Also observed was a relatively high incidence of culture negativity and gram negative culture positivity rates among some Asian–Pacific countries. These findings imply that primary treatment for CAPD peritonitis in these countries should involve the use of a single broad spectrum antibiotic or two antibiotics with gram positive and negative coverage. the median pseudomonas peritonitis rate of 12% means that antibiotics with anti‐pseudomonas activity should also be used. the use of oral vs intraperitoneal (i.p.) drug treatment for established CAPD peritonitis has considerable attraction in Asia because of its reduced cost and ease of administration especially in countries with poor transport arrangement between home and the treatment centre and inadequate home social support. the fluoroquinolones have been extensively studied most in the region and achieve cure rates comparable to conventional i.p. regimens. However, with long‐term use, progressive development of bacterial resistance has been observed and this would ultimately limit their effectiveness. the introduction of oral fluconazole has not reduced the chance of catheter removal but is recommended for the treatment of fungal (especially candida) peritonitis in Asia as it is relatively safe, cheap and simple to use. Oral nystatin given with each antibiotic prescription is also effective in reducing the incidence of candida peritonitis and is inexpensive. Peritonitis secondary to Mycobacterium tuberculosis is more often observed in Asia because the latter is endemic in the region. In contrast to previous recommendations, we have shown from a much larger experience that catheter removal is not mandatory for the cure of this condition and this approach is compatible with long‐term preservation of peritoneal function.
Dialysis‐related amyloidosis: Pathogenetic aspects and therapeutic considerations
Authors: SCHAEFFER JUERGEN , EHLERDING GOETZ , KOCH KARL M
Published: April 2007

Summary: Beyond renal transplantation and the provision of symptomatic relief, approaches to treat dialysis‐related amyloidosis (DRA), an important long‐term complication in patients on regular dialysis, must be based on the knowledge of the underlying pathogenetic process. Retention of beta2‐microglobulin (β2m) is the prerequisite; biochemical alterations of β32m increasing its amyloidogenicity, and local predisposing tissue factors together with age appear to be relevant. A growing body of evidence points toward the importance of pro‐inflammatory effects of dialysis (blood‐membrane interactions, pyrogen‐related priming of cytokine producing mononuclear cells) in the development of DRA. Advanced glycation endproduct formation (AGE‐β2m) may represent a central element in the pathogenesis of DRA. For non‐transplant therapy of DRA, the main goals must be the optimization of β2m removal (high‐flux haemodialysis, haemofiltration, especially pre‐dilution haemofiltration) and reduction of pro‐inflammatory effects of dialysis (use of non‐complement activating biocompatible membranes, pyrogen free dialysate). At least patients at high risk for DRA should be treated according to these guidelines.
The effect of erythropoietin on the cardiovascular system
Authors: LEE DAVID BN , ZHANG ZESONG , HU MING‐SHU , JAMGOTCHIAN NORA , BARRETT JACK D , WARD HARRY J , EGGENA PETER
Published: April 2007

Summary: Partial correction of uraemic anaemia restores the baseline hyperkinetic haemodynamics toward normal, reduces left ventricular size and mass and improves exercise tolerance in dialysis patients. These effects may, in large part, be attributed to increases in haematocrit. Information on whether erythropoietin also acts directly on the heart, as it does on the peripheral vasculature, is not available. Also remaining unanswered is the question as to whether the effects of erythropoietin on the heart reduce cardiovascular mortality in end‐stage renal disease (ESRD) patients. In addition, we do not know whether complete (vs partial) correction of uraemic anaemia will further enhance the beneficial effect of erythropoietin, or whether such gains could be counterbalanced by side effects of erythropoietin, such as the development or exacerbation of hypertension. Studies in the peripheral vasculature suggest erythropoietin also acts directly on the vascular smooth muscle cells, exerting both vasopressive and growth effects. Better understanding of the mechanism and control of such non‐erythropoietic actions of erythropoietin can optimize the beneficial effect and minimize the side effect of this hormone on the cardiovascular system.
Is there a value of erythropoietin in pre‐dialysis patients?
Authors: GOKAL R
Published: April 2007

Summary: The use of erythropoietin (EPO) in anaemic dialysis patients is now well established: there is still some doubt, however, of its role in pre‐dialysis patients. This was based on initial animal work that showed accelerated decline in the renal function. Since then several studies in pre‐dialysis patients have shown that it is both effective and safe. For patients who are anaemic (haematocrit <30%), there is marked increase in their subjective well‐being and ability to perform physical work. There is therefore no reason to deny EPO therapy to pre‐dialysis patients who are symptomatic from anaemia. the evidence clearly shows that contrary to animal work, there is no accelarated progression in renal failure. There is is some evidence that it may even delay the need for dialysis in children and possibly in some adults. In patients who have rapid progression, it is more related to untreated hypertension. Some 30‐40% of EPO treated pre‐dialysis patients need initiation of or increase in anti‐hypertensive therapy. Subcutaneous (s.c.) self administration (1–3/week) is convenient and accepted by patients. Detection and correction of iron deficiency plays an essential role in maximizing the success of EPO therapy. Oral iron is convenient and satisfactory in most patients. Ferrokinetic studies reveal similar findings as in dialysis patients. There is increase in effective erythropoeisis, except in patients who are on azathioprine (pre‐dialysis failing transplants) where the effect may be blunted by an increase in ineffective erythropoeisis. Erythropoietin improves the quality of life in predialysis patients. the most important side effect is development of hypertension, which can be controlled.
New treatment modalities for paediatric kidney disease
Authors: DENG CHUN , TOKIEDA KEIKO , SCHEINMAN JON I , CHAN JAMES CM
Published: April 2007

Summary: The new modalities of treating nephrotic syndrome, chronic renal insufficiencies, renal osteodystrophy and the use of recombinant human growth hormone and insulin‐like growth factors are reviewed in order to provide the nephrologist caring for children an informed choice of therapies.
Prognosis in IgA nephropathy
Authors: PACKHAM David
Published: April 2007

Summary: IgA nephropathy it is now widely recognized as the most common glomerulonephritis causing end‐stage renal failure (ESRF) in many parts of the world. Large series of patients have been analysed in an attempt to identify prognostic clinical and histological features. Increasingly the importance of stage specific analysis of such factors has been reflected in the literature. Such analysis suggests that if therapeutic trials are to be conducted in an attempt to improve prognosis in IgA nephropathy these will need to be organized on a multicentre basis under the auspices of an international organization.
Idiopathic membranous glomerulonephritis in Brazil
Authors: COSTA Roberto S , CINTRA Luiz C
Published: April 2007

Summary: A survey of the medical records and renal biopsy reports of 41 patients with a diagnosis of membranous glomerulonephritis seen at the University Hospital, Faculty of Medicine of Ribeirão Preto, University of São Paulo was undertaken between 1961 and April 1992. Twenty‐three of these patients were found to have idiopathic membranous glomerulonephritis (IMG) and 22 of them were treated with corticosteroids and/or immunosuppressants. Data for these 22 patients showed that the age at clinical presentation was 36.3± 17.5 years, white skin colour predominated (14 patients), and 15 were males; nephrotic syndrome was the clinical presentation in 20 patients and proteinuria was accidentally discovered in two patients. On the first hospital visit 11 patients presented proteinuria of up to 3 g/24 h and 16 presented serum creatinine below 1.5 mg/dL, and 14 developed renal hypertension during follow up. Clinicalmorphological correlation permitted us to conclude (in agreement with the literature) that advanced patient age, intensity of proteinuria, serum creatinine levels above 1.5 mg/dL on the occasion of the first hospital visit, and arterial hypertension are clinical‐laboratory factors indicating a poor prognosis for IMG. More advanced staging of glomerular damage, presence of segmental mesangial sclerosis and tubulointerstitial involvement are microscopic factors indicating a poor prognosis for IMG.
Dialysate and substitution fluid quality for on‐line haemodiafiltration and haemofiltration
Authors: SATO Takashi , TAKAMIYA Tomi , KIM Sung‐Teh , YAMAMOTO Chieko , FUKUI Hiroyoshi , NAKAMOTO Masahiko
Published: April 2007

Summary: A multicentre study concerning the fluid quality for on‐line haemodiafiltration/haemofiltration (GDF/HF) treatment was carried out to assure safety and biocompatibility, and a standard for fluid quality has been established. Endotoxin (ET) concentration in the substitution fluid of not less than 1 IU/L caused minimally, yet significantly greater body temperature rises than those less than 1 IU/L (0.52 ± 0.49 vs 0.08 ± 0.40°C, P > 0.01) when 20L of volume was replaced by 4h post dilution HDF treatment. the post treatment plasma levels for tumour necrosis factor‐α but not interleukin‐6 were correlaed with the amplitude of temporal body temperature rise (r= 0.75, P > 0.01). By sticking to the standard for on‐line HDF/HF treatment that calls for the ET levels in the proportioned dialysate before and the substitution fluid after serial ultrafiltration to be > 50 IU/L and 1 IU/L, respectively, no such deleterious symptoms as fever and hypotension have been observed. Moreover, no enhancement of the plasma ET levels was detected after the first and 6 months of on‐line HDF treatment. In conclusion, the newly established advisory standard assures safety and improved biocompatibility of the on‐line HDF/HF treatment.
Factors affecting the therapeutic response of enalapril in treatment of post transplant erythrocytosis
Authors: SZETO CC , LUI SF , WANG AYM , LI PKT , LAI KN
Published: April 2007

Summary: Enalapril was used for post transplant erythrocytosis (PTE) in 19 stable male hypertensive renal allograft recipients. Post transplant erythrocytosis was defined as haematocrit (Hct) >0.45 for 3 consecutive months. Dosage of enalapril was adjusted according to the blood pressure of individual patients and varied from 2.5 mg to 20 mg per day in divided doses. Patients’serum creatinine level, blood pressure and haematocrit were monitored. Therapeutic response was expressed as percentage drop in Hct (Δ%Hct). Factors affecting Δ%Hct was then determined. After 32 weeks of treatment, haematocrit fell from 0.495 ± 0.021 to 0.396 ± 0.053, which represented a 19.9% drop (paired Student's t‐test, P > 0.001). With multiple regression analysis, reciprocal of plasma creatinine (RCr) prior to enalapril therapy (B = 3.40 ± 0.72, P > 0.0005), dose of enalapril adjusted with bodyweight (B = ‐ 0.058 ± 0.020, P > 0.02, and pre‐treatment haematocrit level (B = ‐ 1.90 ± 0.71, P > 0.02) were found to be independent factors affecting Δ%Hct. We concluded that the dosage of enalapril, renal allograft function and severity of erythrocytosis were the major factors affecting the therapeutic response of PTE by enalapril treatment.
Growth hormone and renal function
Authors: HISANO Satoshi , LATTA Kay , KRIEG Richard J , CHAN James CM
Published: April 2007

Summary: Recombinant human growth hormone (rhGH) has been recognized to be beneficial for improving growth retardation in uraemic children. the potential effect of growth hormone (GH) on renal haemodynamics results in an increase in glomerular filtration rate and renal plasma flow. However, in GH transgenic mice and uraemic rats treated with GH, GH has been reported to aggravate glomerular sclerosis and induce deterioration in renal function. Therefore, the potential of adverse effect of GH on deterioration in renal function has been of concern in uraemic children receiving rhGH. Growth hormone enhances protein anabolism and promotes a positive nitrogen balance. It is more likely that the anabolic effect of GH used at the conventional dose may reduce renal solute load and slow the progression of end‐stage renal failure (ESRF) in rhGH‐treated uraemic children. A low protein diet with adequate calories slows the deterioration of renal function in uraemic patients. the effects of GH on growth promotion, renal haemodynamics and protein anabolism are mainly mediated by insulin‐like growth factor‐I (IGF‐I). Insulinlike growth factor‐I enhances glomerular filtration rate and promotes glomerular hypertrophy, but IGF‐I administration is unlikely to give rise to glomerular sclerosis. the efficacy and the safety of concomitant therapy of recombinant GH or IGF‐I and low protein diet should therefore be considered in uraemic children.
Mitochondrial function in partially nephrectomized rats
Authors: HARRIS David CH , CHEN Juchuan , TAY Yuet‐ching
Published: April 2007

Summary: Previous demonstrations of increased oxygen consumption and renal iron accumulation in partially nephrectomized (RK) rats on the one hand, and acute mitochondrial toxicity of iron in normal rats on the other suggest a complex relationship between mitochondrial function and iron. Renal cortical mitochondrial respiratory function was therefore investigated in RK and iron‐loaded rats. State 4 (resting) respiration was increased in RK rats (49±1 vs 43±1 natom 0/min, P. <0.001) in comparison to control. Mitochondrial enzyme activity was lower in RK than control rats (e.g. succinate dehydrogenase 158.2 ± 13.6 vs 237.2±17.4 Δlog[cyt C]/min/mg/prot, P<0.01). Acute iron‐loading impaired creatinine clearance (1.39 ± 0.07 vs 0.40 ± 0.29 mL/min) and mitochondrial enzyme activity (e.g. cytochrome oxidase 362.0 ± 32.8 vs 185.0 ± 46.6 Δlog[cyt C]/min/mg/prot, P<0.05) in control rats, but RK rats were more resistant to injury and there was no change in mitochondrial enzyme activity. Mitochondrial fragility was similar in RK and control rats, and in both was unaffected by iron‐loading. In conclusion, rates of resting mitochondrial respiration are increased in partially nephrectomized rats, despite reduced intrinsic activity of two iron‐dependent mictchondrial enzymes. Mitochondrial function is more resistant to acute injury with iron in partially nephrectomized rats.
Structural heterogeneity of glycans in IgA molecules: Implications for IgA nephropathy
Authors: MESTECKY Jiri , TOMANA Milan
Published: April 2007

Summary: The carbohydrate moieties on glycoproteins, including immunoglobulins (Ig), are involved in a broad spectrum of biological functions. As revealed by enzymatic or chemical removal of carbohydrate moieties, inhibition of glycosylation, or site‐directed mutagenesis of asparagine residues to prevent N‐linked glycosylation, carbohydrates on Ig have been shown to participate in binding, internalization and catabolism by hepatocytes or other cells, binding to Fc receptors on phagocytic cells, activation of complement, and opsonization. the structure of human IgA1 is unique among all Ig. the heavy chain contains a hinge region with a characteristic primary structure not seen in any other Ig, and which contains five short O‐linked oligosaccharide side‐chains composed of serine‐linked N‐acetylgalactosamine (GalNAc) and βl‐3‐linked galactose (Gal). Both of these monosaccharides may be sialylated. In contrast to ubiquitous N‐linked side‐chains, O‐linked carbohydrate moieties are found rarely among human serum glycoproteins. We have demonstrated that IgA1 proteins from the sera of patients with IgA nephropathy (IgAN) are galactosylated to a lesser extent than those from healthy controls. Decreased content of Gal and decreased reactivity of IgA from IgAN patients with lectins specific for GalNAc indicate that these structural changes occur on glycans located in the hinge region of IgA1. Thus, in addition to rheumatoid arthritis, systemic lupus erythmatosus, inflammatory bowel disease and other disorders, IgA nephropathy may represent another example of a chronic disease in which aberrancies of carbohydrates are observed and may participate in aetiopathogenesis.
Transporter‐associated with antigen processing genes in primary IgA glomerulonephritis
Authors: EL‐DEEB Salem , BERTHOUX Patricia , CÉCILLON Simone , DIAB Nabil , FILIPPIS Jean‐Pierre DE , ALAMARTINE Eric , BERTHOUX Franclois
Published: April 2007

Summary: Transporter‐associated with antigen processing (TAP1 and TAP2) gene products are involved in the transport/processing of self‐peptides from cytosol into endoplasmic reticulum (ER). In ER, these peptides associate with human leucocyte antigen (HLA)‐class I molecules for further presentation at cell surface. Deficient processing and/or presentation could lead to altered self‐tolerance resulting in autoimmunity. We studied TAP1 and TAP2 genes and genotypes frequencies in 49 controls and in 101 patients with primary IgA nephritis (IgAN). the patients were divided into two groups: 45 patients with end‐stage renal failure (ESRF) and 56 patients with normal kidney function (NKF). DNA was extracted from peripheral blood and amplified by double amplification refractory mutation system‐polymerase chain reaction (ARMS‐PCR) using appropriate primers for the two point‐mutations on TAP1 genes and for the three point‐mutations on TAP2 genes, which are the basis of TAP polymorphism. We have found a weak association between TAP2‐p379‐VAL/ILE genotype and total‐IgAN (24%vs 12% in controls; P= 0.05). However, the analysis of a subgroup of IgAN patients bearing HLA‐B35 antigen, a former poor prognosis marker, disclosed an association between the TAP2‐1993Ntd‐Guanine variant (coding for TAP2‐p665‐ALA): 31% in B35‐ESRF‐IgAN subgroup vs 6% in controls (P=0.04) and 13% in B35‐NKF‐IgAN (P=NS). the complexity of immunogenetic studies in IgAN is further increased by the existence of two opposite pathological subgroups: normal glomerular basement membrane (GBM) thickness vs thin‐GBM. There was a complex relation in IgAN between this TAP2 variant and the following parameters: ESRF, HLA‐B35, and normal‐GBM. Further investigations are therefore needed.
Altered immunity in circulation of patients with IgA nephropathy
Authors: YANO Aohiro , SAKAI Hideto , KUROKAWA Kiyoshi
Published: April 2007

Summary: Several abnormalities of the immune system are assumed to be involved in the development of IgA nephropathy (IgAN). the roles of cytokines and other soluble factors, which may interact mutually in peripheral circulation, have been studied by many investigators who believed that analysis of the source and function of such factors might provide a significant clue in order to disclose the mechanisms of development of IgAN. Changes in B cell immunity such as enhanced production of IgA or IgE have been reported in IgAN. B cells in IgAN also showed enhanced expression of CD23 (Fc&RII) on their surface. Th2 cell derived pleiotropic cytokine, interleukin (IL)‐4 is known as potent inducer for CD23, IgE and IgA. In IgAN, synthesis of IL‐4 is enhanced both in vivo and in vitro. Th1 derived cytokine, interferon (IFN)‐γ is a antagonist to Th2 derived cytokines. Although, in vitro synthesis of the cytokine is unexpectedly increased in IgAN, its suppressive effects against IL‐4 are, at least partially, impeded in IgAN. Under this condition, relatively enhanced Th2 like cell activity may help to keep B cell activation in IgAN. Increased numbers of human leukocyte antigen (HLA)‐DR bearing natural killer (NK) cells are observed in IgAN. These HLA positive NK cells simultaneously express high IFN‐γ genes. These NK cells are possibly the source of increased IFN‐γ in IgAN and play a compensatory roles for suppressed Th1‐like cells. Interferon‐γ production by NK cells in IgAN is probably regulated by IL‐12. Although the source of IL‐12 in circulation has not been determined, characteristically activated B cells in IgAN, other than macrophages, may have some relation to this IL‐12 ‐ NK‐ IFN‐γ cascade. the HLA‐bearing rate of NK cells in IgAN showed a positive relation to rapidity of progression of renal dysfunction in a long‐term follow‐up study. These findings suggested that IgA specific changes in peripheral cell interaction involving Th2‐like cells, B cells, macrophages and NK cells may be able to induce local inflammatory events in the kidneys.
A THERMAL SHOCK FATIGUE STUDY OF TYPE 304 AND 316 STAINLESS STEELS
Authors: MARSH D. J.
Published: April 2007

Abstract—

–Thermal fatigue crack initiation and propagation promoted by thermal quenches have been studied in AISI 316 and 304 stainless steels and correlated with isothermal strain cycling fatigue. Axially unconstrained specimens of rectangular section were held at bulk temperatures of 250°C to 500°C and symmetrically water‐quenched on the narrow faces to give equivalent surface strain ranges from 2.8 ×10−3 to 5.4 ×10−3. Crack initiation in smooth samples showed an apparent threshold at a surface strain range of 2.8×10−3 equivalent to a thermal amplitude of 150°C with no cracking being produced in 500,000 cycles. The crack growth in prenotched samples was evaluated by direct observation and by subsequent fractography and showed two modes of growth. The crack growth was strain controlled during the early stages of propagation where the crack tip was within the surface zone under conditions of fully plastic cyclic yield. At greater depths the propagation rates in the remaining elastically cycled material were found to correlate with calculated stress intensity values. In the chosen symmetrical quenched axially unconstrained configuration the crack growth rates decreased towards the centre of the specimen, indicating a crack arrest condition as expected from analysis. The results indicated a good correlation with the fracture behaviour observed from isothermal strain cycling fatigue behaviour in an air environment.
ELECTRICAL POTENTIAL MONITORING OF CRACK FORMATION AND SUBCRITICAL GROWTH FROM SMALL DEFECTS
Authors: GANGLOFF R. P.
Published: April 2007

Abstract —An experimental method was developed to quantify the formation and subcritical propagation of small cracks emanating from artificial surface defects. Continuous crack depth information was obtained from dc electrical potential measurements employing an analytical model. Fatigue experiments were conducted to evaluate the crack monitoring procedures for conditions relevant to the elevated temperature defect tolerance of superalloys. Cracking progressed uniformly and predictably from small surface defects (0.1 mm deep and 1.4 mm long) in A286, 304 and 10Ni steels and in René 95 and MP–159 superalloys. Crack depths, computed based on analytical calibration of measured electrical potentials, agreed to within ±18% of corresponding values measured optically. Similar results were obtained for a penny‐shaped defect, 75 μm deep. Applications of the technique were investigated, including characterizations of fatigue crack formation and growth in René 95.
ANALYSIS OF COMBINED STATIC AND FATIGUE CRACK GROWTH DATA
Authors: RHODES D. , RADON J. C. , CULVER L. E.
Published: April 2007

Abstract —Three methods are presented, whereby' static’(R‐curve) and fatigue crack growth data may be combined. In the first, a single curve is fitted through both sets of data, making due allowance for residual stresses from prior unloading and stress ratio. For the other two methods, crack growth is divided into tearing and ductile striation formation components. These components may be combined either by adding crack growth rates associated with specified values of stress intensity factor or by adding crack growth resistances associated with specified crack extensions. The results are compared with test data obtained from compact tension specimens of high strength aluminium alloys, BS.L97 (2024–T3) and DTD.5120 (7010–T7651).
FATIGUE CRACK GROWTH UNDER MIXED MODE LOADING
Authors: PATEL A. B. , PANDEY R. K.
Published: April 2007

Abstract —Mixed mode fatigue crack growth is analysed using Sih's strain energy density approach. A centre crack panel geometry loaded under uniaxial cyclic tension is considered. The crack angle is varied from 30° to 90°. A procedure for the determination of crack propagation life is outlined. The crack trajectory due to cyclic loading is predicted. The crack growth rate, the cyclic life and the cyclic life ratio are discussed, for an aluminium alloy and a steel, as a function of initial crack angle, crack length, stress amplitude, and the strain energy density factor.
LOW‐ AND HIGH‐CYCLE FATIGUE PROPERTIES OF VARIOUS STEELS SPECIFIED IN JIS FOR MACHINE STRUCTURAL USE
Authors: TANAKA K. , NISHIJIMA S. , MATSUOKA S. , KOUZU F.
Published: April 2007

Abstract —Low‐cycle fatigue properties were investigated on four carbon steels and five low alloy steels specified in JIS (Japanese Industrial Standard) for machine structural use, which are the most commonly used in Japan. Several different heats from each of several representative manufacturers were sampled so as to represent the average fatigue characteristics of current materials. The cyclic deformation behaviour of material was denned by comparing the monotonie yield stress on the extrapolated tensile work hardening curve with the cyclic yield stress in the cyclic stress‐strain curve determined by incremental step test. The normalized ferrite‐pearlitic steels cyclically hardened, while the quench‐tempered martensitic were cyclically stable or softened. The S–N relations derived from the strain‐controlled low‐cycle tests were compared with the results obtained by load‐controlled high‐cycle tests. The extrapolated S–N curves based on the cyclic stress‐strain curve predicted the fatigue strength in the high‐cycle range to be stronger for cyclic‐hardening steels, but weaker for cyclic‐softening steels. The predicted S–N curves for stable steels coincided with the high cycle test data. The fatigue limit had a proportional relationship with cyclic yield stress, slightly depending on the cyclic deformation behaviour. On the other hand, the cyclic yield stress was found to exhibit a very good linear correlation with the monotonie tensile strength, independent of cyclic deformation behaviour. This explains the empirical law that the fatigue limit is approximately proportional to the tensile strength.
THE HYSTERESIS LOOP 3. STRESS‐DIP EXPERIMENTS
Authors: POLÁK J. , KLESNIL M. , HELEŠIC J.
Published: April 2007

Abstract— A stress‐dip technique for the determination of an effective stress in cyclic straining has been improved. The critical stress drop, ΔσC, for which zero strain relaxation rate is observed can be obtained from experiments. The significance of this quantity is discussed in terms of the statistical theory of the hysteresis loop. The measurements of the effective stress at different temperatures and along the hysteresis loop are reported. The observed asymmetry of stress in cyclic straining is ascribed to asymmetry of effective stress.
A CRACK‐TIP‐ZONE INTERACTION MODEL FOR CREEP‐FATIGUE CRACK GROWTH
Authors: Jaske Carl E.
Published: April 2007

Abstract— A crack‐tip‐zone interaction model for creep‐fatigue crack growth is proposed. The basic details of the model are described. Experimental evidence in support of this model is presented. Existing data on creep‐fatigue crack growth interaction agree qualitatively with the model. Some quantitative evidence for the model is presented and more is being developed in current work.
THE BEHAVIOUR OF FATIGUE CRACKS SUBJECT TO APPLIED BIAXIAL STRESS: A REVIEW OF EXPERIMENTAL EVIDENCE
Authors: Smith E. W. , Pascoe K. J.
Published: April 2007

Abstract— Experimental studies aimed at understanding the fatigue process in metals and polymers have usually been performed under uniaxial stress. Only in the last two decades or so has much experimentation been carried out on fatigue crack propagation under biaxial stress. This paper reviews the available published data. Crack propagation behaviour under biaxial stress is dictated by 3 parameters: stress biaxiality itself, which is defined here as the ratio of the in‐plane principal stresses, crack angle with respect to the applied principal stress directions and stress intensity factor range. Depending on the first two parameters, cracks may grow in Mode I, Mode II or Mixed‐Mode. Crack growth data have been presented using these three divisions. Two short sections have been included on initiation and cyclic stress/strain behaviour under biaxial stress to emphasise the fact that crack growth cannot be fully understood without knowing something of them. The accumulated data do not lead to adequate conclusions on either the qualitative or quantitative behaviour of cracks subject to cyclic in‐plane biaxial stress. Reasons for the confusion and even contradiction of independent results are put forward and some discussion given to the possible directions of future experimental work.
A PROPOSED CRITERION FOR FATIGUE THRESHOLD: DISLOCATION SUBSTRUCTURE APPROACH
Authors: Lucas J. P. , Gerberich W. W.
Published: April 2007

Abstract— A model for fatigue threshold has been proposed based on the dislocation subgrain cell structure that evolves at the crack tip in steels during the fatigue deformation process. The stabilized subgrain cells that develop in the material act as impenetrable barriers to dislocations in slip band pile‐ups that emanate from the fatigue crack tip. The blocking of these dislocations tends to limit crack growth that occurs by crack tip emission of dislocations, thereby leading ultimately to the fatigue threshold condition. The grain size effect on threshold is deduced to be an indirect effect as it is proposed that the subgrain cell size is the controlling substructural parameter at the threshold stress intensity level. The subgrain cell size is shown to be proportional to the one‐third power of the initial grain size.
SHORT CRACK PROPAGATION AND CLOSURE EFFECTS IN A508 STEEL
Authors: Breat J. L. , Mudry F. , Pineau A.
Published: April 2007

Abstract— Fatigue crack growth measurements are usually made on standard specimens containing long cracks (∼10 mm) although in most practical situations, a large part of the fatigue life is spent with much shorter dimensions. The purpose of the present study is a comparison of crack growth behaviour for long cracks (∼13–16 mm) in CT specimens and smaller ones (∼0.3–0.5 mm) in four point bend specimens. Large effects are noticed indicating that, at a given stress intensity factor amplitude, the crack growth rate is significantly higher in specimens with short cracks. Mouth displacement measurements for both specimen configurations show that the crack closure phenomenon accounts for the observed effect. Crack closure is likely to be associated with fracture surface roughness as shown by partly machining the material left behind the crack tip in CT specimens.
EFFECTS OF SHORT‐TERM HEATING CYCLES ON FATIGUE CRACK GROWTH IN 7075‐T651
Authors: Wilkinson, Rodney L. , Potter John M. , Papazian John M.
Published: April 2007

Changes in the crack growth behavior of 7075‐T651 aluminum specimens which had been exposed to temperatures between 121 and 179°C were evaluated. Specimens were fatigue tested at room temperature under flight‐by‐flight loading conditions. Results from these tests were then compared with data from the as‐received material. Exposure to 141°C or more produced a definite increase in specimen life, apparently due to a decrease in crack growth rate. In contrast, preliminary experiments using constant amplitude loading did not show noticeable effects of these thermal treatments on fatigue lifetime. The thermal treatments were found to cause overaging of the metastable precipitate microstructure, which was thought to be responsible for the changes in fatigue response.
THE EFFECT OF REST PERIODS ON THE FATIGUE STRENGTH OF Ti‐6A1‐4V
Authors: Brown C. W. , Smith G. C.
Published: April 2007

The monitoring of fatigue crack initiation mechanisms and short fatigue crack growth usually involves interrupting otherwise continuous load cycling for examination of the test‐piece. This permits attainment of high resolution over a large area of surface where the fatigue cracks could initiate. However, breaks in the fatigue cycling can affect the fatigue endurance of the test‐piece and in the present study of Ti‐6A1‐4V this has been shown to depend on the duration of the rests, the number of cycles between rests, the type of examination employed and the hydrogen content of the material. The results of the work are discussed in terms of the possible influence of the monitoring technique on the fatigue process.
A MICRO‐MECHANICS ANALYSIS FOR SHORT FATIGUE CRACK GROWTH
Authors: Rios E. R. de los , Mohamed Hussain J. , Miller K. J.
Published: April 2007

Crack initiation and early growth of fatigue cracks in a fully annealed 0.4% carbon steel was investigated using plastic replicas and torsion loading.

In a structure consisting of a 70/30 mixture of pearlite and ferrite the cracks are seen to develop and grow initially along slip bands in the ferrite phase. Energetic considerations lead to the formulation of a model which, while characterizing short crack growth rate, also considers those microstructural variables relevant to fatigue crack initiation and early crack growth. The driving force for crack growth is provided by the energy of the slip band; correspondingly crack growth per cycle is proportional to the strength of the slip band.

In the short fatigue crack region, cracks grow initially at a fast rate but deceleration occurs quickly and, depending on the stress level, they either arrest or are temporarily halted at a critical length. This critical length is shown to coincide with the value of the threshold length for crack growth under LEFM conditions.
FATIGUE AT NOTCHES SUBJECTED TO REVERSED TORSION AND STATIC AXIAL LOADS
Authors: Brown M. W. , Hay E. , Miller K. J.
Published: April 2007

Reversed torsion with and without a superimposed end load has been applied to 1% Cr‐Mo‐V steel specimens containing sharp notches. Crack propagation was monitored by a sensitive d.c. potential drop system that measured crack depths between 25 μm and 0.6 mm from the root of the notch.

Stress intensity factors do not satisfactorily correlate all the crack growth data but a strain intensity factor which is a function of material properties and notch plastic zone size shows a significant improvement and provides a single upper bound solution for both ambient and elevated temperatures. This solution permits designers to make safe lifetime assessments.

At room temperature cracks initially propagate by mode II along the surface, and mode III radially but at low stresses crack growth is continued by mode I propagation. At higher stresses a transition to mode I cracking is avoided. Elevated temperature causes a brittle layer to form and in this case cracks initially propagate by mode I which then translates to mode III cracking at high stresses.

Mode III thresholds are significantly higher than mode I thresholds but a constrained shear strain zone, as found at the root of notches subjected to torsion, permits the initiation and generation of a mode III crack. The application of an axial load enhances the mode III crack propagation rate since this increases the effective crack tip intensification factor.
CONSIDERATIONS OF ALLOWABLE STRESS OF CORROSION FATIGUE (FOCUSED ON THE INFLUENCE OF PITTING)
Authors: Kawai S. , Kasai K.
Published: April 2007

Abstract— Long life corrosion fatigue behaviour is discussed. The importance of (i) quantification of corrosion pit depth (or surface roughness caused by corrosion) as a function of service period and (ii) corrosion pit modelling is emphasized. Extreme value statistics is useful for corrosion pit depth quantification. It is demonstrated that a corrosion pit can be treated as an elliptical crack with the same depth and surface length as a pit. From these considerations, a method for determination of a reasonable allowable stress in corrosion fatigue is proposed. Finally, an example of an allowable stress is given, i.e. the allowable stresses of a real machine component under rotating bending stress are determined from estimation curves of pit depth together with corrosion fatigue crack growth data.
INFLUENCE OF TEMPERATURE ON FATIGUE CRACK GROWTH BEHAVIOUR OF STEELS AT ULTRASONIC FREQUENCY
Authors: PuškÁr A. , Várkoly L.
Published: April 2007

Fatigue crack growth rates have been measured at 22 kHz for two types of carbon steel, between 20 and 500°C under symmetrical push‐pull loading. The crack length was determined from the decrease in the resonant frequency of the specimen. For ČSN 412013 steel, an increased crack propagation resistance was observed between 250 and 300°C. The values of the constants C and n in the Paris equation, and Ka,th are dependent on temperature. The fatigue crack growth rate and C both increase with temperature, while n and Ka,th decrease with increasing temperature. Electron scanning and light microscopy have shown that intercrystalline fracture does not occur in ČSN 415313 steel at elevated temperature. Intercrystalline fracture was observed for specimens fatigued at 20°C and also in ČSN 412013 steel at temperatures of 200 and 500°C. The width of the plastic zone and the height of the surface relief around the fatigue crack increased with temperature.
FATIGUE LIFE PREDICTION IN BENDING FROM AXIAL FATIGUE INFORMATION
Authors: Manson S. S. , Muralidharan U.
Published: April 2007

Bending fatigue in the low cyclic life range differs from axial fatigue due to the plastic flow which alters the linear stress‐strain relation normally used to determine the nominal stresses. An approach is presented in this report to take into account the plastic flow in calculating nominal bending stress Sbending based on true surface stress. For a given surface strain εS, hence the surface life (NS), an equation is derived to express Sbending in terms of axial fatigue stress (Saxial), involving material constants c, b, NT which are obtained from axial fatigue information and f1 and f2 which are functions of strain hardening exponent and depend on the geometry of cross‐section. These functions are derived in closed form for rectangular and circular cross‐sections. The nominal bending stress and the axial fatigue stress are plotted as a function of life (NS) and these curves are shown for some materials of engineering interest.
CRACK GROWTH BEHAVIOUR OF FATIGUE MICROCRACKS IN LOW CARBON STEELS
Authors: Suh C. M. , Kitagawa H.
Published: April 2007

The behaviour of low carbon steels has been studied, in particular the initiation and growth of the major crack which led to final fracture of smooth specimens, via surface replica and photomicrograph techniques. From this study, the fracture process and fatigue life prediction characterized by the growth of surface microcracks have been analysed by a new approach unifying the conventional approaches based on the final fracture of materials with the fracture mechanics approach. Knowledge of fracture parameters is critical for non‐destructive inspection during service life and the application of fracture mechanics to life prediction and assessment.
CRACK TIP PLASTIC ZONE SIZES IN CYLINDRICAL BARS SUBJECTED TO TORSION
Authors: Yates J. R.
Published: April 2007

Abstract— Plastic zone sizes in circumferentially cracked round bars in torsion are estimated using an adaptation of the strip yield model. Results are compared with those from elastic‐plastic finite element solutions for elastic‐perfectly plastic and strain hardening material conditions, as well as with previously published data. The strip yield model gives results which are in close agreement with the finite element solutions over a wide range of torques.
DETERMINATIONS OF JIC FOR 2024‐T351 ALUMINIUM ALLOY
Authors: Beaver P. W. , Heller M. , Rose T. V.
Published: April 2007

Abstract— The J‐integral is an elastic‐plastic fracture mechanics parameter which can be regarded as a measure of the intensity of the crack tip stress and strain fields, irrespective of the plastic zone size. The value of J at the onset of stable crack extension, JIC, has been suggested as a fracture criterion for both large‐and small‐scale yielding conditions. In this work the value of JIC for an extruded, medium‐strength aluminium alloy, 2024‐T351 bar, was determined using; (i) the Hutchinson‐Rice‐Rosengren crack tip model and experimentally‐determined crack tip strain profiles; and (ii) the ASTM standard multiple‐specimen technique. Knowing the critical load for initial crack extension from the crack tip strain profile method also enabled JIC to be computed using a finite element‐hybrid contour method and a modified linear elastic fracture mechanics approach. Agreement between the JIC values obtained by the various methods was good.
COMBINED MODE FRACTURE OF A DUCTILE MATERIAL UNDER PLANE STRESS CONDITIONS
Authors: Qi Yang‐Xian , Fan Wei‐xun
Published: April 2007

Abstract— On the basis of our experimental results on Ly12‐CZ (similar to 2024‐T3) aluminium alloy tensile sheet specimens and Tresca's theory, a fracture criterion for a combined mode crack in ductile materials under plane stress conditions is proposed.
FATIGUE CRACK GROWTH BEHAVIOUR OF A ZINC‐ALUMINIUM ALLOY AT HIGH HOMOLOGOUS TEMPERATURES
Authors: Shin C. S. , Smith R. A.
Published: April 2007

Abstract— The fatigue crack growth behaviour and crack closure response of a zinc base die casting alloy at high homologous temperature were studied. The crack growth rate was both frequency and temperature dependent. The frequency dependence of crack growth rate, which has been commonly attributed to creep‐fatigue interaction, can be rationalized by the crack closure phenomenon. The temperature dependence is contrary to that observed in other materials and cannot be simply explained in terms of the interaction between creep and fatigue damage. The effect of a single tensile overload on the crack growth behaviour at high homologous temperatures has also been investigated.