Common cancer-related symptoms among GP patients. Opportunistic screening in primary health care

OBJECTIVE

To study the occurrence of symptoms related to the five most common forms of cancer among patients regularly visiting primary care. To estimate the proportion of symptoms needing GP examination, and the number of tumours thus diagnosed.

DESIGN

Patients with some form of non-malignant chronic disease received a letter with information about cancer-related symptoms along with an invitation to regular check-up. The letter described the most common symptoms of breast, colorectal, lung, prostate and skin cancers.

SETTING

12 health centres in Kalmar County, Sweden.

SUBJECTS

5200 patients aged over 40 years.

RESULTS

One patient in 13 reported cancer-related symptoms to the GP. Women reported more symptoms than men, and almost half of them had had symptoms at previous check-ups. The GP was able to explain 7 out of 10 patients' symptoms directly. When other symptoms were examined, 8 cancers were diagnosed as well as 6 pre-malignant tumours, corresponding to 3 tumour diagnoses per 1000 check-ups.

CONCLUSION

While attending regular check-ups, patients may not report symptoms which cause anxiety and sometimes indicate serious diseases. It is possible to widen the perspective and link both primary and secondary prevention of certain cancers to the check-up.

Circulating human antisperm antibodies recognize prostasomes

PROBLEM

The presence of naturally occurring antisperm antibodies (ASA) is a well-known cause of infertility in men and women, but the antigens for these antibodies are usually poorly characterized. Prostasomes, organelles secreted by human prostatic acinar cells and expelled into the seminal plasma at ejaculation, can adhere to sperm cells. Thus, we have examined whether prostasomes could be an antigen for ASA.

METHOD OF STUDY

We have studied the reactivity of chicken antiprostasome antibodies with sperm cells in an agglutination test and conversely the reactivity of serum positive for ASA from 20 infertile patients, with spermatozoa using flow cytometry and with purified prostasomes using enzyme-linked immunosorbent assay.

RESULTS

The chicken antiprostasome antibody caused agglutination of sperm cells similarly to the agglutination observed with patients' sera. All of these patients' sera contained IgG antibodies against prostasomes.

CONCLUSIONS

The high percentage of patients with antiprostasome antibodies in this study shows that prostasomes could be one of the major targets for ASA.

Multipotent hematopoietic progenitor cells immortalized by Lhx2 self-renew by a cell nonautonomous mechanism

OBJECTIVE

Direct molecular and cellular studies of hematopoietic stem cells (HSCs) are hampered by the low levels of HSCs in hematopoietic tissues. To address these issues, we generated immortalized multipotent hematopoietic precursor cell (HPC) lines by expressing the LIM-homeobox gene Lhx2 (previously LH2) in hematopoietic progenitors derived from embryonic stem cells differentiated in vitro.

MATERIALS AND METHODS

To validate further the relevance of the HPC lines as a model for normal HSCs, we analyzed in detail the growth requirements of HPC lines in vitro.

RESULTS

Lhx2 immortalized the HPC lines by a putatively novel and cell nonautonomous mechanism. Self-renewal of the HPC lines is dependent on functional Lhx2 expression. Most early-acting hematopoiesis-related growth factors show synergistic effects on the HPC lines, whereas late-acting factors do not induce differentiation by themselves. Transforming growth factor-beta(1) is a potent inhibitor of proliferation of the HPC lines. HPC lines form cobblestone areas with high efficiency when seeded onto stromal cell lines, and the cobblestone area-forming cell can be maintained in these cultures for several months.

CONCLUSIONS

Our data show that, in many respects, HPC lines are similar to normal hematopoietic progenitor/stem cells on the cellular level, in contrast to most previously described multipotent hematopoietic cell lines. The cell nonautonomous mechanism for immortalization of the HPC lines suggests that Lhx2 regulates, directly or indirectly, soluble mediators involved in self-renewal of the HPC lines.

Female gender does not influence the magnitude of ibutilide-induced repolarization delay and incidence of torsades de pointes in an in vivo rabbit model of the acquired long QT syndrome

BACKGROUND

Clinical and experimental in vitro observations indicate that female gender is associated with a higher risk of developing torsades de pointes with repolarizing-delaying agents. The present study addressed the question of gender difference in the susceptibility towards developing torsades de pointes in a rabbit model of the acquired long QT syndrome in vivo.

METHODS AND RESULTS

Female (F, n = 40) or male (M, n = 40) NZW rabbits, characterized as young (Y, n = 20) or adult (A, n = 20) were anesthetized with alpha-chloralose and sensitized to developing torsades de pointes by a continuous infusion of methoxamine. The class III antiarrhythmic agent ibutilide was subsequently infused at a rate of 8 nmol/kg/min for 30 minutes maximum. Before commencement of drug infusion, no gender-related differences in the QT interval were observed (121 +/- 1.9 msec and 126 +/- 3.3 msec in FA and in MA and 116 +/- 1.6 msec and 113 +/- 1.7 msec in the FY and MY, respectively). Infusion of ibutilide was associated with a rapid and marked increase in the QT interval, which did not differ significantly between the groups. Hence, the maximal QT lengthening observed was 39 +/- 3.1% in FA, 46 +/- 5.7% in MA, 38 +/- 3.9% in FY and 36 +/- 3.4% in MY, respectively (p > 0.05 between gender). In the adults, the incidence of torsades de pointes in F was 70% and in M 90% (p = 0.235), whereas in the young, the incidence in F was 45% and in M 70% (p = 0.200). The cumulative doses of ibutilide causing torsades de pointes were not statistically significantly different between the four groups of rabbits (70 +/- 15.5 nmol/kg in FA, 50 +/- 5.3 nmol/kg in MA, 59 +/- 17.2 nmol/kg in FY and 61 +/- 15.9 nmol/kg in MY, respectively).

CONCLUSIONS

In this in vivo rabbit model of the acquired long QT syndrome, female gender was not associated with a longer repolarization time (QT interval), an excessive change in the baseline QT interval or a higher incidence of torsades de pointes in response to ibutilide challenge.

Leptin levels show diurnal variation throughout puberty in healthy children, and follow a gender-specific pattern

OBJECTIVE

To investigate the levels and diurnal rhythm of serum leptin in healthy children, and to investigate the association between leptin levels and sex steroids.

METHODS

Four girls and four boys, all healthy volunteers, were followed longitudinally throughout puberty. Their chronological ages ranged from 8.7 to 19.5 years, and body composition, expressed as weight-for-height standard deviation scores (SDS), ranged between -1.7 and +2.4. Serum leptin, oestradiol and testosterone concentrations were measured by radioimmunoassay at 1000, 1400, 1800, 2200, 0200 and 0600 h.

RESULTS

In all girls and boys, both prepubertally and during pubertal development, serum leptin levels increased during the night, with no difference in relative peak amplitude. In boys, the leptin concentrations increased until the initiation of puberty and then declined, whereas in girls, the concentrations increased throughout puberty. The inter-individual variation in mean leptin levels among girls decreased to 11% at the time of menarche. A positive correlation was found for both oestradiol and testosterone versus leptin in girls throughout puberty (r=0.64 and r=0.71 respectively, P<0.001). A negative correlation was found between leptin and testosterone in boys in mid- and late puberty (r=-0.66, P<0.01). No correlation was found between oestradiol and leptin in boys or between testosterone and leptin in pre- and early pubertal boys.

CONCLUSION

Serum leptin concentrations show diurnal variation throughout pubertal development in both girls and boys. The changes in leptin levels during puberty follow a gender-specific pattern, probably due to an influence of sex steroids on leptin production.

Interferon-alpha promotes survival of human primary B-lymphocytes via phosphatidylinositol 3-kinase

Signaling pathways for the antiviral and antiproliferative biological effects of type I interferons (IFN) are well established. In this report we demonstrate a novel signaling pathway for IFN-alpha, as it induced rapid phosphorylation of both PKB/Akt and its substrate forkhead. The PI3-kinase inhibitor LY294002 abolished these phosphorylations. PI3-kinase has been implicated in cell survival mediating its effect through the second messenger PIP3 and the subsequent activation of PKB/Akt. We could show that IFN-alpha inhibited spontaneous apoptosis of primary B-lymphocytes, in the absence of a mitogenic stimulus. This effect was inhibited by LY294002. Thus, our data suggests that IFN-alpha promotes survival of peripheral B-lymphocytes via the PI3-kinase-PKB/Akt pathway. In addition, IFN-alpha stimulation of anti-IgM activated cells resulted in downregulated expression of the cell cycle inhibitor p27/Kip1.

Prostasome-like granules from the PC-3 prostate cancer cell line increase the motility of washed human spermatozoa and adhere to the sperm

OBJECTIVE

Prostasome-like granules are present in the PC-3 prostate cancer cells. Since the seminal prostasomes are able to promote the forward motility of human spermatozoa, we conducted a study to determine whether PC-3 prostasomes exerted effects similar to those of seminal prostasomes on buffer-washed spermatozoa from normospermic semen samples.

STUDY DESIGN

We used computer-assisted sperm analysis (CASA) and immunostaining of prostasomes to find out where these granules are located on the spermatozoa.

RESULTS

Addition of PC-3 prostasomes increased the proportion of motile spermatozoa from 12-15% to 50-70% (p<0.001). The optimal protein concentration of these prostasomes was 0.1mg/ml. Heat treatment of PC-3 prostasomes did not decrease their motility-promoting effect. Immunostaining with anti-prostasome monoclonal antibody (mAb78) revealed that the PC-3 prostasomes and seminal prostasomes adhered to the sperm cells. The staining, which occurred all over the spermatozoa, was intense on the mid-pieces and weaker on the sperm heads. Herewith, some prostasome component may activate the spermatic mitochondrial function, thus increasing sperm motility.

CONCLUSION

It is concluded that PC-3 prostasomes bear a functional resemblance to seminal prostasomes as regards sperm motility promotion.

Instability and triangulation of the action potential predict serious proarrhythmia, but action potential duration prolongation is antiarrhythmic

BACKGROUND

Prolongation of action potential duration (APD) is considered a major antiarrhythmic mechanism (class 2I), but paradoxically, it frequently is also proarrhythmic (torsade de pointes).

METHODS AND RESULTS

The cardiac electrophysiological effects of 702 chemicals (class 2I or HERG channel block) were studied in 1071 rabbit Langendorff-perfused hearts. Temporal instability of APD, triangulation (duration of phase 3 repolarization), reverse use-dependence, and induction of ectopic beats were measured. Instability, triangulation, and reverse use-dependence were found to be important determinants of proarrhythmia. Agents that lengthened the APD by >50 ms, with induction of instability, triangulation, and reverse use-dependence (n=59), induced proarrhythmia (primarily polymorphic ventricular tachycardia); in their absence (n=19), the same prolongation of APD induced no proarrhythmia but significant antiarrhythmia (P<0.001). Shortening of APD, when accompanied by instability and triangulation, was also markedly proarrhythmic (primarily monomorphic ventricular tachycardia). In experiments in which instability and triangulation were present, proarrhythmia declined with prolongation of APD, but this effect was not large enough to become antiarrhythmic. Only with agents without instability did prolongation of APD become antiarrhythmic. For 20 selected compounds, it was shown that instability of APD and triangulation observed in vitro were strong predictors of in vivo proarrhythmia (torsade de pointes).

CONCLUSIONS

Lengthening of APD without instability or triangulation is not proarrhythmic but rather antiarrhythmic.

Changes in non-22-kilodalton (kDa) isoforms of growth hormone (GH) after administration of 22-kDa recombinant human GH in trained adult males

GH is being used by elite athletes to enhance sporting performance. To examine the hypothesis that exogenous 22-kDa recombinant human GH (rhGH) administration could be detected through suppression of non-22-kDa isoforms of GH, we studied seventeen aerobically trained males (age, 26.9 +/- 1.5 yr) randomized to rhGH or placebo treatment (0.15 IU/kg/day for 1 week). Subjects were studied at rest and in response to exercise (cycle-ergometry at 65% of maximal work capacity for 20 min). Serum was assayed for total GH (Pharmacia IRMA and pituitary GH), 22-kDa GH (2 different 2-site monoclonal immunoassays), non-22-kDa GH (22-kDa GH-exclusion assay), 20-kDa GH, and immunofunctional GH. In the study, 3 h after the last dose of rhGH, total and 22-kDa GH concentrations were elevated, reflecting exogenous 22-kDa GH. Non-22-kDa and 20-kDa GH levels were suppressed. Regression of non-22-kDa or 20-kDa GH against total or 22-kDa GH produced clear separation of treatment groups. In identical exercise studies repeated between 24 and 96 h after cessation of treatment, the magnitude of the responses of all GH isoforms was suppressed (P < 0.01), but the relative proportions were similar to those before treatment. We conclude: 1) supraphysiological doses of rhGH in trained adult males suppressed exercise-stimulated endogenous circulating isoforms of GH for up to 4 days; 2) the clearest separation of treatment groups required the simultaneous presence of high exogenous 22-kDa GH and suppressed 20-kDa or non-22-kDa GH concentrations; and 3) these methods may prove useful in detecting rhGH abuse in athletes.

Desmin-related myopathies in mice and man

Desmin, the main intermediate filament (IF) protein in skeletal and heart muscle cells, is of great importance as a part of the cytoskeleton. The IFs surround and interlink myofibrils, and connect the peripheral myofibrils with the sarcolemma. In myotendinous junctions and neuromuscular junctions of skeletal muscle fibres, desmin is enriched. In the heart, desmin is increased at intercalated discs, the attachment between cardiomyocytes, and it is the main component in Purkinje fibres of the conduction system. Desmin is the first muscle-specific protein to appear during myogenesis. Nevertheless, lack of desmin, as shown from experiments with desmin knockout (K/O) mice, does not influence myogenesis or myofibrillogenesis. However, the desmin knock-out mice postnatally develop a cardiomyopathy and a muscle dystrophy in highly used skeletal muscles. In other skeletal muscles the organization of myofibrils is remarkably unaffected. Thus, the main consequence of the lack of desmin is that the muscle fibres become more susceptible to damage. The loss of membrane integrity leads to a dystrophic process, with degeneration and fibrosis. In the heart cardiac failure develops, whereas in affected skeletal muscles regenerative attempts are seen. In humans, accumulations of desmin have been a hallmark for presumptive desmin myopathies. Recent investigations have shown that some families with such a myopathy have a defect in the gene coding for alphaB-crystallin, whereas others have mutations in the desmin gene. Typical features of these patients are cardiac affections and muscle weakness. Thus, mutations in the desmin gene is pathogenic for a distinct type of muscle disorder.

Methods of collecting and evaluating non-clinical cardiac electrophysiology data in the pharmaceutical industry: results of an international survey

OBJECTIVE

To assess current practice in the pharmaceutical industry for assessing the potential for QT interval prolongation by non-cardiovascular medicinal products.

METHODS

The survey was based on responses from the Toxicology and (Safety) Pharmacology laboratories (a total of 74 laboratories) of 54 companies based in Europe, Japan/Asia and the USA, received between January and March 1999.

RESULTS

All 54 companies conducted preclinical in vivo electrocardiography (EGG) evaluation of new active substances (NASs). Thirty of these companies also conducted in vitro cardiac electrophysiology studies on their compounds. The majority of in vivo work was done in conscious beagle dogs. There was no consistency within the industry in defining the magnitude of change in QT interval that is considered biologically important. Most companies considered a change greater than 10% to be important, although the design of the studies suggested that group sizes used may not give sufficient statistical power to detect this size of change. Bazett's formula was used by 41% of laboratories to correct QT for changes in heart rate, despite the fact that this formula is generally deemed to be unsuitable for use in dogs. For studies in anaesthetised dogs, the majority of laboratories used barbiturate anaesthesia, but researchers should be aware of the effects of this and some other anaesthetic agents on QT interval. As for in vitro cardiac electrophysiology, there was wide diversity in the testing methodologies, particularly with regard to the test species and tissue type. As with QT prolongation, there was no consensus on the degree of action potential prolongation to cause concern. For both in vitro and in vivo testing, the majority of companies tested a minimum of three dose (or concentration) levels in order to ascertain any dose-response relationship.

CONCLUSIONS

The survey provides a snapshot of the practice in the industry prior to any internationally-agreed consensus on the most effective and efficient approaches to minimising the risk of QT prolongation by new drugs in man. It must be stated that for any given methodology, the 'majority view' in the industry is not necessarily best practice.

Does metal backing improve fixation of tibial component in unicondylar knee arthroplasty? A randomized radiostereometric analysis

In a prospective, randomized study, patients with medial gonarthrosis stage I to III according to Ahlbäck were allocated to a unicondylar knee arthroplasty (Miller-Galante, Zimmer, Inc., Warsaw, IN) with an all-polyethylene tibial component or metal-backed tibial component of the same design. The purpose of the study was to evaluate if metal backing enhanced tibial component fixation. A total of 45 knees (42 patients; 23 metal-backed components and 22 all-polyethylene components) were examined. We used radiostereometric analysis to measure micromotion of the tibial component over a period of 2 years after surgery. Hospital for Special Surgery score was used for clinical evaluation. We found no statistically significant differences in clinical results or migration of the tibial component over a 2-year follow-up period. These findings do not support better fixation of metal-backed tibial components. Because of these findings, we advocate all-polyethylene tibial components in unicondylar knee arthroplasties because of optimal biomechanical strength at a given height of tibial component, avoiding potential problems of modularity and minimizing the amount of interfaces, at a lower cost.

Potassium and calcium current blocking properties of the novel antiarrhythmic agent H 345/52: implications for proarrhythmic potential

OBJECTIVES

To study the blocking effects of H 345/52 on ionic currents of rabbit ventricular myocytes and how these features translate into a proarrhythmic potential.

METHODS

The single electrode voltage clamp technique was used to study the effects of H 345/52 on the rapid component of the delayed rectifying potassium current, I(Kr), and the L-type calcium current (I(Ca)). Differential effects of H 345/52 and almokalant on APD prolongation were studied in a rabbit Purkinje fibre/ventricular muscle preparation. The temporal variability of the action potential duration (APD) and its relation to proarrhythmias was examined in Langendorff-perfused rabbit hearts administered H 345/52 or almokalant. Anaesthetised, methoxamine-sensitised rabbits were used to assess the propensity of intravenous H 345/52 and ibutilide to induce torsades de pointes (TdP).

RESULTS

H 345/52 potently blocked I(Kr) (IC(50)=40 nM) without consequential use-dependency. The I(Ca) was also blocked, but at higher concentrations (IC(50)=1.3 microM). Block of I(Ca) was markedly frequency-dependent (positive) and influenced by membrane potential, such that H 345/52 was more effective following clamp steps from plateau potentials than from -80 mV. In the Purkinje fibre-ventricular muscle preparation, almokalant prolonged the Purkinje fibre APD preferentially, whereas H 345/52 homogeneously prolonged APD in both tissue types. In the perfused rabbit heart, H 345/52 (1 microM) and almokalant (0.3 microM) prolonged APD to a similar degree but increased the temporal variability of APD differently, from 3+/-0.4 ms in control hearts to 8+/-1.2 ms and to 38+/-7.5 ms (P<0.001 vs. H 345/52), respectively. Unequivocal early after-depolarisations were seen in 5/6 almokalant-perfused hearts but in no heart administered H 345/52 (P<0.05). In anaesthetised rabbits, H 345/52 (17.4 micromol/kg) or ibutilide (2.6 micromol/kg maximum), maximally lengthened the QT interval from 133+/-4.5 to 177+/-8.0 ms and from 125+/-5.1 to 166+/-9.3 ms (P<0.001, n=8). However, whereas ibutilide induced TdP in all animals at 0.06+/-0.009 micromol/kg, H 345/52 did not induce TdP (P=0.0002) at up to 17.4 micromol/kg.

CONCLUSIONS

H 345/52 blocks I(Kr) with high potency and I(Ca) with somewhat lower potency and was found to delay ventricular repolarisation without substantially increasing temporal or spatial dispersion and without inducing early after-depolarisations or TdP.

Concave versus posterior-stabilized tibial joint surface in total knee arthroplasty: randomized evaluation of 47 knees

Forty-seven knees in 43 patients with severe deformities randomly received AMK total knee arthroplasty with concave (C, n = 25) or posterior-stabilized (PS, n = 22) polyethylene insert and with resection of the posterior cruciate ligament. Radiostereometric examinations were done postoperatively and after 3, 12, and 24 months. Two patients (1 C, 1 PS) underwent revision surgery. At the 2-year follow-up, the median absolute rotations of the tibial inserts ranged from 0.13 degrees to 0.26 degrees (C vs PS; P =.1-.7). The maximum total point motion was almost identical in the 2 groups (C, 0.38; PS, 0.39; P =.9). Maximum subsidence, lift-off, and Hospital for Special Surgery scores did not differ (P =.1-.6). Recipients of 20 of 24 knees with concave design and 14 of 19 knees with posterior-stabilized design reported that their knee could be regarded as normal or almost normal. Variations of the configuration of the polyethylene insert did not alter the outcome in the short term.

Autoantibodies to prostasomes as new markers for prostate cancer

Prostate cancer is one of the leading causes of cancer-related death among men. Given the varying clinical course and the long natural history of the disease, it is important to have good diagnostic and prognostic markers. Prostate specific antigen (PSA) is currently the best marker for the detection of prostate cancer, but in many cases it does not reveal whether metastases have appeared. Since metastases of prostate cancer release prostasomes, which are immunogenic secretory granules of both normal and neoplastic prostate cells, we checked whether anti-prostasome antibodies will appear when the cancer is metastasing. In a pilot study, all 13 patients with serum PSA between 50-500 microg/L had anti-prostasome antibodies, while 39 healthy controls with low PSA values showed background values. There was no overlapping, i.e. the upper range value of controls did not reach the lower range value of patients.

The response of molecular isoforms of growth hormone to acute exercise in trained adult males

Circulating GH consists of multiple molecular isoforms, all derived from the one gene in nonpregnant humans. To assess the effect of a potent stimulus to pituitary secretion on GH isoforms, we studied 17 aerobically trained males (age, 26.9 +/- 1.5 yr) in a randomized, repeat measures study of rest vs. exercise. Exercise consisted of continuous cycle ergometry at approximately 80% of predetermined maximal oxygen uptake for 20 min. Serum was assayed for total, pituitary, 22-kDa, recombinant, non-22-kDa, 20-kDa, and immunofunctional GH. All isoforms increased during, peaked at the end, and declined after exercise. At peak exercise, 22-kDa GH was the predominant isoform. After exercise, the ratios of non-22 kDa/total GH and 20-kDa GH/total GH increased and those of recombinant/pituitary GH decreased. The disappearance half-times for pituitary GH and 20-kDa GH were significantly longer than those for all other isoforms. We conclude that 1) all molecular isoforms of GH measured increased with and peaked at the end of acute exercise, with 22-kDa GH constituting the major isoform in serum during exercise; and 2) the proportion of non-22-kDa isoforms increased after exercise due in part to slower disappearance rates of 20-kDa and perhaps other non-22-kDa GH isoforms. It remains to be determined whether the various biological actions of different GH isoforms impact on postexercise homeostasis.

Direct effects of growth hormone on production and secretion of apolipoprotein B from rat hepatocytes

The aim of this study was to investigate the direct effects of growth hormone (GH) on production and secretion of apolipoprotein B (apoB)-containing lipoproteins from hepatocytes. Bovine GH (5-500 ng/ml) was given for 1 or 3 days to rat hepatocytes cultured on laminin-rich matrigel in serum-free medium. The effects of GH were compared with those of 3 nM insulin and 500 microM oleic acid. GH increased the editing of apoB mRNA, and the proportion of newly synthesized apoB-48 (of total apoB) in the cells and secreted into the medium changed in parallel. GH increased total secretion of apoB-48 (+30%) and apoB-48 in very low density lipoproteins (VLDL) more than twofold. Total apoB-100 secretion decreased 63%, but apoB-100-VLDL secretion was unaffected by GH. Pulse-chase studies indicated that GH increased intracellular early degradation of apoB-100 but not apoB-48. GH had no effect on apoB mRNA or LDL receptor mRNA levels. The triglyceride synthesis, the mass of triglycerides in the cells, and the VLDL fraction of the medium increased after GH incubation. Three days of insulin incubation had effects similar to those of GH. Combined incubation with oleic acid and GH had additive effects on apoB mRNA editing and apoB-48-VLDL secretion. In summary, GH has direct effects on production and secretion of apoB-containing lipoproteins, which may add to the effects of hyperinsulinemia and increased flux of fatty acids to the liver during GH treatment in vivo.

In vivo kinematics of total knee arthroplasty: flat compared with concave tibial joint surface

This study evaluated the influence of the geometric configuration of the tibial joint area on the kinematics of the knee. Twenty-two patients with noninflammatory arthritis and minor preoperative deformity were studied. They each received an AMK total knee replacement with retention of the posterior cruciate ligament. Eleven patients without any knee abnormalities were used as controls. The patients were stratified to either the flat (terminology of the manufacturer: standard) or concave (terminology of the manufacturer: constrained) polyethylene insert (n = 11 in each group). Knee kinematics were assessed 1 year after the operation by having the patient ascend a platform corresponding to an extension of the knee from 50 to 70 degrees of flexion. During this motion, two film-exchangers simultaneously exposed six to 13 pairs of serial stereoradiographs. The concave geometric configuration of the tibial insert resulted paradoxically in increased anterior-posterior translations compared with the flat insert but no significant change of rotations and translations in the other directions. Compared with normal knees, the most obvious abnormality was increased anterior-posterior translations (p < 0.004). At 50 degrees of flexion, the implants with the flat tibial polyethylene insert had displaced 2 times and the concave ones had displaced 2.5 times more posteriorly than the normal knees (p < or = 0.001). Less internal tibial rotation was also recorded in the flexed positions for both types of inserts compared with the normal knees (p < 0.02). Four knees in four patients, who reported symptoms of instability and abnormal knee function, showed significantly increased proximal displacement of the center of the tibial plateau in the flexed position. The findings suggest that current prosthetic designs and surgical technique do not restore normal knee kinematics and indicate that design improvements should rely on in vivo kinematic studies.

Lentivirus vector gene expression during ES cell-derived hematopoietic development in vitro

The murine embryonal stem (ES) cell virus (MESV) can express transgenes from the long terminal repeat (LTR) promoter/enhancer in undifferentiated ES cells, but expression is turned off upon differentiation to embryoid bodies (EBs) and hematopoietic cells in vitro. We examined whether a human immunodeficiency virus type 1-based lentivirus vector pseudotyped with the vesicular stomatitis virus G protein (VSV-G) could transduce ES cells efficiently and express the green fluorescent protein (GFP) transgene from an internal phosphoglycerate kinase (PGK) promoter throughout development to hematopoietic cells in vitro. An oncoretrovirus vector containing the MESV LTR and the GFP gene was used for comparison. Fluorescence-activated cell sorting analysis of transduced CCE ES cells showed 99.8 and 86.7% GPF-expressing ES cells in the VSV-G-pseudotyped lentivirus (multiplicity of infection [MOI] = 59)- and oncoretrovirus (MOI = 590)-transduced cells, respectively. Therefore, VSV-G pseudotyping of lentiviral and oncoretrovirus vectors leads to efficient transduction of ES cells. Lentivirus vector integration was verified in the ES cell colonies by Southern blot analysis. When the transduced ES cells were differentiated in vitro, expression from the oncoretrovirus LTR was severely reduced or extinct in day 6 EBs and ES cell-derived hematopoietic colonies. In contrast, many lentivirus-transduced colonies, expressing the GFP gene in the undifferentiated state, continued to express the transgene throughout in vitro development to EBs at day 6, and many continued to express in cells derived from hematopoietic colonies. This experimental system can be used to analyze lentivirus vector design for optimal expression in hematopoietic cells and for gain-of-function experiments during ES cell development in vitro.

Growth-inhibitory effect of prostasomes on prostatic cancer cell lines in culture

OBJECTIVES

Prostasomes, small corpuscular organelles derived from the prostate gland, were isolated from human seminal plasma for incubation with three human prostatic cancer cell lines: DU145, PC3, and LNCaP. The aim of this study was to establish any possible growth-inhibitory effect of prostasomes on prostatic cancer cell lines.

METHODS

Prostasomes were isolated from human seminal plasma. We determined their growth-inhibitory effect on the prostatic cancer cell lines by a fluorimetric cytotoxic assay technique. The results obtained were presented as survival index, defined as a percentage of control cultures, after compensation for blank values.

RESULTS

The prostasomes exhibited a dose-dependent growth-inhibitory effect on the cells, cell line DU145 being the most sensitive one displaying a survival index (mean +/- SD) of 46+/-10% at 200 microg prostasomes (protein)/ml while the other two cell lines displayed survival indices of 93+/-6 and 93+/-9%. Heat treatment of the prostasomes abolished their growth-inhibitory effect on the cell lines, whereas 24-hour dialysis of the prostasomes did not affect their activity in this regard. Seminal plasma devoid of prostasomes exhibited less effect on the growth of these cancer cell lines, and heat treatment of the plasma did not influence the result. However, dialysis of the seminal plasma for 24 h abrogated its growth-inhibitory effect.

CONCLUSION

The prostasomal growth-inhibitory effect on the cancer cell lines was different from that of the prostasome-free seminal plasma. The former effect was most probably of a proteinaceous nature while the latter effect was most likely due to the divalent cation composition of seminal plasma. In this regard, the zinc ion content seemed to be decisive.

Tibial component fixation in porous- and hydroxyapatite-coated total knee arthroplasty: a radiostereo metric evaluation of migration and inducible displacement after 5 years

A total of 51 knees (45 patients) with osteoarthrosis were stratified in a randomized study to receive a hydroxyapatite-coated Freeman-Samuelson (FS HA) or a porous-coated Miller-Galante II (MG II) uncemented total knee arthroplasty. Repeated clinical, radiographic, and radiostereometric analysis (RSA) evaluations of the tibial components were done for 5 years. The clinical outcome was equal at the 5-year follow-up (mean Hospital for Special Surgery score, 93). Standard radiographs displayed more zones around the tibial stem in the MG II group. RSA revealed that the FS HA components migrated less (smaller maximum total point motion and maximum subsidence) after 5 years and showed less inducible displacements at the 1-year follow-up. The stability of the implants obtained is equal to or better than cemented implants after 5 years. Key words: knee prosthesis, cementless, hydroxyapatite, radiostereometry, inducible displacement.

Antibacterial activity of human prostasomes

BACKGROUND

Prostasomes are prostate-derived organelles in semen exhibiting pluripotent properties. The present study deals with their possible antibacterial effects.

METHODS

Antibacterial activity was assessed by growth inhibition of bacteria in an incubation medium containing prostasomes, after which the incubate was inoculated on cystine lactose electrolyte deficient agar (CLED) plates. In cases involving Bacillus megaterium, the effects were also documented ultrastructurally with scanning electron microscopy and atomic force microscopy.

RESULTS

A dose-dependent growth inhibition was apparent, and a complete inhibition of growth was seen at a prostasome protein concentration of 30 microg/ml with Bacillus megaterium. Ultrastructurally, increasingly irregular contours and a loosening of the smooth surface were observed, combined with a fragmentation of the bacteria. Among 9 other bacterial strains tested, a complete growth inhibition by prostasomes was attained in 3 strains, while the other 6 were unaffected.

CONCLUSIONS

Our data suggest that prostasomes, or prostasome-derived proteins, are responsible for the antibacterial effects on Bacillus megaterium and some other bacterial strains. The results may serve as a basis of development of a new class of antibacterial drugs.

Differences in the distribution of synemin, paranemin, and plectin in skeletal muscles of wild-type and desmin knock-out mice

Mice lacking the gene encoding for the intermediate filament protein desmin have a surprisingly normal myofibrillar organization in skeletal muscle fibers, although myopathy develops in highly used muscles. In the present study we examined how synemin, paranemin, and plectin, three key cytoskeletal proteins related to desmin, are organized in normal and desmin knock-out (K/O) mice. We show that in wild-type mice, synemin, paranemin, and plectin were colocalized with desmin in Z-disc-associated striations and at the sarcolemma. All three proteins were also present at the myotendinous junctions and in the postsynaptic area of motor endplates. In the desmin K/O mice the distribution of plectin was unaffected, whereas synemin and paranemin were partly affected. The Z-disc-associated striations were in general no longer present in between the myofibrils. In contrast, at the myotendinous and neuromuscular junctions synemin and paranemin were still present. Our study shows that plectin differs from synemin and paranemin in its binding properties to the myofibrillar Z-discs and that the cytoskeleton in junctional areas is particularly complex in its organization.

Growth hormone induces CCAAT/enhancer binding protein alpha (C/EBPalpha) in cultured rat hepatocytes

BACKGROUND/AIMS

The transcription factor CCAAT/enhancer binding protein alpha (C/EBPalpha) is a transactivator of several genes in the liver, which are regulated by growth hormone.

METHODS

Growth hormone (100 ng/ml) was added to primary rat hepatocytes cultured on a laminin-rich matrix. C/EBP mRNA and protein levels were measured by RNase protection assay and Western blotting, respectively. DNA binding activity was measured by electrophoretic mobility shift assay (EMSA).

RESULTS

Growth hormone treatment for 6 h to 3 days increased C/EBPalpha mRNA levels. Addition of growth hormone for 24 h and 4 days also enhanced the levels of the 42 and 30 kDa isoforms of immunoreactive C/EBPalpha. EMSA showed that addition of growth hormone for 24 h enhanced the abundance of a protein complex binding to a consensus C/EBP binding DNA oligonucleotide. This protein complex was supershifted by antibodies directed against C/EBPalpha but not against C/EBPbeta. There were no consistent effects on C/EBPbeta mRNA or protein at any timepoint. The growth hormone effect on C/EBPalpha expression was not affected by simultaneous incubation with insulin or glucocorticoids, two hormones that previously have been reported to affect C/EBPs.

CONCLUSIONS

Growth hormone enhances the levels of C/EBPalpha mRNA and protein as well as the DNA binding activity of C/EBPalpha in cultured rat hepatocytes.

[Use of new materials results in improved prostheses. Metals, polymers, ceramics and composite materials extend durability]

Advances in our knowledge of multifactorial host-biomaterial interactions have improved the outcome of joint replacement surgery. Fixation and aseptic loosening are the principal foci of research. Wear debris from articulating parts is a major cause of prosthetic loosening. Tri-biological analysis, and the development of new materials and surface finishes have reduced wear particle production. The use of modular implants increases flexibility and facilitates surgical fit, but also introduces new problems such as dissociation of components, corrosion and wear. In the future, as design, biomaterials and surgical technique become further optimized, arthroplasty may also become an alternative for use in younger patients.

Some factors affecting enantiomeric impurity determination by capillary electrophoresis using ultraviolet and laser-induced fluorescence detection

The key factors influencing enantiomer trace determination were investigated; these include resolution capillary diameter, limit of detection, linear range and type of detection. Chiral reagents, (+)- and (-)-1-(9-fluorenyl)ethyl chloroformate (FLEC), were employed as probes to demonstrate the influence of the variables. In order to find the best resolution, separation variables were optimized in both capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC) modes by the application of factorial design experiments. A highly efficient chiral separation of the (+/-)-FLEC, derivatized with nonchiral amino acids, was achieved when using gamma-cyclodextrin as the chiral selector. The benefits of using a small diameter capillary for direct determination of both (+) and (-)-FLEC impurity (0.05-0.1% area/area) were demonstrated using UV detection and applying a sample stacking condition. A frequency-doubled argon ion laser (244 nm) was used as light source for laser-induced fluorescence (LIF) detection. Excitation light was provided by means of an optical fiber directed into the Hewlett Packard 3D capillary cartridge. The signals from UV and LIF were monitored simultaneously. The application of LIF detection greatly improved sensitivity and linear range. Further, as a consequence of the increased sensitivity, sample loading could be decreased, which led to an improvement of separation efficiency. Direct determination of 0.005% impurity could be achieved within the linear range.

Nestin is expressed during development and in myotendinous and neuromuscular junctions in wild type and desmin knock-out mice

Desmin, the main component of intermediate filaments (IFs) in mature skeletal muscle, forms an interlinking scaffold around myofibrils with connections to the sarcolemma and the nuclear membrane. Desmin is enriched in neuromuscular and myotendinous junctions. Mice lacking the desmin gene develop normally and reproduce. However, postnatally they develop a cardiomyopathy and a dystrophy in highly used muscles. We have investigated whether and how neuromuscular and myotendinous junctions are affected and whether nestin compensates for the lack of desmin in the knock-out (K/O) mice. We show that neither neuromuscular nor myotendinous junctions were markedly affected in the desmin K/O mice. In neuromuscular junctions nestin was present between the postjunctional folds and the subneural nuclei and between the nucleus and the myofibrillar cytoskeleton. In myotendinous junctions nestin was present between myofibrils at the Z-disc level and in longitudinal strands close to and at the junction. Nestin expression at these specialized sites, as well as during myogenesis and myofibrillogenesis, is independent of the presence of desmin. In desmin K/O mice nestin was also found in regenerating myofibers. The presence of nestin at neuromuscular and myotendinous junctions might provide enough strength for preservation and organization of the junctional areas, although desmin is lacking.

[New materials improve joint prostheses. Metals, polymers, ceramics and composite materials extend the durability]

Advances in our knowledge of multfactorial host-biomaterial interactions have improved the outcome of joint replacement surgery. Fixation and aseptic loosening are the principal foci of research. Wear debris from articulating parts is a major cause of prosthetic loosening. Tribological analysis, and the development of new materials and surface finishes have reduced wear particle production. The use of modular implants increases flexibility and facilitates surgical fit, but also introduces new problems such as dissociation of components, corrosion and wear. In the future, as design, biomaterials and surgical technique become further optimised, arthroplasty may also become an alternative for use in younger patients.

Metabolic fates in humans of linamarin in cassava flour ingested as stiff porridge

Insufficiently processed products from cassava roots may contain residual amounts of cyanogenic glucosides, mainly linamarin. The fate of orally ingested linamarin was studied following a meal of cassava porridge prepared from cassava flour from southern Tanzania with 82 mg cyanide equivalents (3035 micromol) of linamarin per kg dry weight. Following ingestion of amounts of porridge containing 243-571 micromol linamarin by 15 healthy adults a mean (range) of 21% (1-47%) of the linamarin ingested was excreted in the urine within 24 hours and a mean of 1% in the next 24 hours. Serum thiocyanate, the main cyanide metabolite, increased in all subjects from a mean (+/-SD) of 34+/-26 to 78+/-28 micromol/litre (P < 0.001). In a second group of seven subjects we found that the ingestion of porridge with a mean (range) of 431 micromol (203-669%) of linamarin resulted in a mean linamarin excretion of 127 micromol/litre and an excess thiocyanate excretion of 118 micromol/litre and that 216 micromol was unaccounted for. We conclude that less than one-half of orally ingested linamarin is converted to cyanide and hence thiocyanate, about one-quarter is excreted unchanged and another quarter is metabolized into an as yet unknown compound.

Eosinophilic inflammation assessed by induced sputum in corticosteroid-dependent asthma

Sputum induction can be used to study airway inflammation in asthmatics. However, it has not been used in patients with corticosteroid-dependent asthma requiring long-term oral corticosteroids. The aim of the study was to assess the number of eosinophils and the levels of eosinophil cationic protein (ECP) in sputum of 17 corticosteroid-dependent asthmatics by comparison with nine mild untreated asthmatics, 10 moderate asthmatics receiving inhaled steroids (ICS) and 11 healthy subjects. In the 17 corticosteroid-dependent asthmatics, we examined sputum eosinophil markers on two occasions and correlated with the control of asthma. Eosinophils were undetectable in controls and were detected in 63.8% of asthmatics. There were no significant differences between the three groups of asthmatics. ECP levels were significantly increased in ICS or corticosteroid-dependent asthmatics by comparison to controls and mild asthmatics. There was no significant difference between ICS and corticosteroid-dependent asthmatics. During follow-up, corticosteroid-dependent asthmatics with a controlled disease had no significant change in eosinophil numbers or ECP levels. On the other hand, corticosteroid-dependent asthmatics with recent exacerbations had a non-significant increase in eosinophil numbers and a significant increase in ECP levels. This study shows that ECP levels may be more accurate than eosinophil numbers in assessing exacerbations in corticosteroid-dependent asthmatics.

Greater increase in cytokine concentration after salvage with filtered whole blood than with washed red cells, but no difference in postoperative hemoglobin recovery

BACKGROUND

Inflammatory mediators are released in association with intraoperative and postoperative salvage of blood. Whether these mediators (cytokines) participate in the modulation of erythropoiesis or not has been investigated.

STUDY DESIGN AND METHODS

Twenty-seven patients who were to undergo total knee replacement surgery were randomly assigned to postoperative blood salvage with either filtered whole blood or washed red cells. Patients with postoperative blood loss <400 mL were considered a control group. The control group did not receive any transfusions. Plasma concentrations of the anaphylatoxin C3a, the C5b-9 terminal complement complex, and the cytokines interleukins 6 and 8, hemoglobin, reticulocytes, and red cell volume fraction in the patients were repeatedly analyzed before and after surgery.

RESULTS

Significantly increased concentrations of interleukin 6 appeared in all three groups, which was interpreted as a response to the surgical trauma. The increase was significantly greater in the group that received filtered whole blood after return of shed blood. The recovery of hemoglobin levels did not differ in the groups.

CONCLUSION

The transfusion of filtered whole blood leads to the formation of interleukin 6 in the circulation, but postoperative hemoglobin recovery was similar in all groups.

Birth weight, adulthood BMI, and subsequent weight gain in relation to leptin levels in Swedish women

OBJECTIVE

Leptin seems to be involved in the regulation of energy balance, although little is known about the epidemiology of leptin with respect to prediction of weight gain and incidence of obesity-related diseases. The dual aim of this study is to document characteristics of leptin after long-term storage, and to describe its relation to body weight, from birth to old age, in an ongoing prospective study.

RESEARCH METHODS AND PROCEDURES

A population-based sample of Swedish women was first examined at the ages of 38 to 60 and re-examined 24 years later. This study used 1358 frozen serum samples that had been stored 29 years for analysis of leptin concentrations and their relation to body weight history.

RESULTS

Leptin values obtained from stored samples showed the same correlation with relative weight as that seen in a contemporary sample with similar demographic characteristics. Lower self-reported birth weight was associated with higher leptin levels in adulthood (p = 0.01), controlling for age and adult BMI. Prospective analyses revealed that high leptin in 38 to 46-year-olds predicted subsequent long-term weight gain (p = 0.003), although no significant associations were seen in women initially aged 50 or older.

DISCUSSION

It is feasible to use frozen serum for studying leptin in relation to obesity and related developments many years later. High leptin level was a risk factor for subsequent weight gain in 38- and 46-year-old women. Retrospective analyses involving birth weight suggest that leptin resistance in adulthood might have fetal origins.

Subsidence of a non-polished stem in revisions of the hip using impaction allograft

We revised 24 consecutive hips with loosening of the femoral stem using impaction allograft and a cemented stem with an unpolished proximal surface. Repeated radiostereometric examinations for up to two years showed a slow rate of subsidence with a mean of 0.32 mm (−2.0 to +0.31). Fifteen cases followed for a further year showed the same mean subsidence after three years, indicating stabilisation. A tendency to retroversion of the stems was noted between the operation and the last follow-up. Retroversion was also recorded when displacement of the stem was studied in ten of the patients after two years. Repeated determination of bone mineral density showed an initial loss after six months, followed by recovery to the postoperative level at two years. Defects in the cement mantle and malalignment of the stem were often noted on postoperative radiographs, but did not correlate with the degrees of migration or displacement. After one year, increasing frequency of trabecular remodelling or resorption of the graft was observed in the greater trochanter and distal to the tip of the stem. Cortical repair was noted distally and medially (Gruen regions 3, 5 and 6). Migration of the stems was the lowest reported to date, which we attribute to the improved grafting technique and to the hardness of the graft.

Identification of dipeptidyl peptidase IV as the antigen of a monoclonal anti-prostasome antibody

BACKGROUND

Our purpose was to elucidate the identity of an antigen of a monoclonal antibody against prostasomes, which are prostate-derived organelles occurring freely in human semen.

METHODS

Monoclonal antibodies against prostasomes were generated by intrasplenic immunization to allow better characterization of the prostasomes. One third of the resulting antibodies bound to a 110-kDa prostasomal protein on Western blots.

RESULTS

The antigen was purified from seminal prostasomes by anion exchange chromatography and gel electrophoresis. After in-gel digestion and amino-acid sequence analysis of selected peptides, it was identified as dipeptidyl peptidase IV (DPP IV), EC 3.4.14.5, also known as T-cell-activating antigen CD26. No DPP IV could be detected in the supernatant obtained after preparative ultracentrifugation of the prostasomes.

CONCLUSIONS

DPP IV/CD26 is structurally bound to prostasomes rather than being free in seminal fluid. This enzyme may play a critical role in the promoting effect of prostasomes on forward motility of spermatozoa.

Hydroxyapatite coating versus cemented fixation of the tibial component in total knee arthroplasty: prospective randomized comparison of hydroxyapatite-coated and cemented tibial components with 5-year follow-up using radiostereometry

Fifty-three consecutive patients (57 knees; mean age, 69 years) entered a prospective randomized study to compare the fixation of hydroxyapatite (HA)-coated (29 knees) with cemented (28 knees) tibial components in the Tricon II total knee arthroplasty. The quality of the fixation during 5 years postoperatively was evaluated with radiostereometric analysis (RSA). Three HA-coated implants were revised: 2 owing to infection, and 1 owing to early delamination of the coating and clinical loosening. Eight patients (9 knees) died, 1 patient sustained a stroke, and 1 patient refused investigations after 1 year. In the 40 patients (19 HA-coated, 21 cemented) remaining at 5 years, the magnitude of the micromotion between the HA-coated and cemented groups did not differ. The HA-coated implants displayed most of the migration within the initial 3 months then stabilized, whereas the cemented implants showed an initially lower, but over time continuously increasing migration. Between 1 and 2 years, 4 of 24 HA-coated and 10 of 23 cemented implants migrated >0.2 mm and were categorized unstable, which has been shown to have a prognostic value as regards future aseptic loosening. Progressive radiolucent lines developed in 2 cemented knees, which both were categorized unstable. If HA-coated implants can sustain the forces that threaten the fixation in the early period after implantation, a strong and enduring fixation may be obtained.

Expression of prostasome-like granules by the prostate cancer cell lines PC3, Du145 and LnCaP grown in monolayer

Prostasomes are a granular type of secretory product in the human prostate gland cells. It is not known, whether in vitro grown cells derived from human prostate cancers also express prostate secretory components containing granules with properties similar to the prostasomes. Therefore, we carried out the present investigation and found that cytospins of in vitro grown PC3, DU145 and LNCaP cells generally expressed a granular secretion. DU145 demonstrated the highest ratio of cells with granules (about 90%), while cytospins of PC3 and LNCaP contained less stained cells (50-70%). Purified granules from PC3 cells were immunoreactive with a monoclonal antibody (mAb78) originally raised against human seminal prostasomes. The PC3 granules also shared the property with human seminal prostasomes having an elevated UV260/UV280 absorbance ratio. On the other hand we found a low aminopeptidase activity in PC3 granules contrary to that of human prostasomes. Prostasomes may form a heterogeneous group with different properties due to the source from which they are isolated and perhaps it is justified to recognize them as different members of a prostasome family.

Subsidence of a non-polished stem in revisions of the hip using impaction allograft. Evaluation with radiostereometry and dual-energy X-ray absorptiometry

We revised 24 consecutive hips with loosening of the femoral stem using impaction allograft and a cemented stem with an unpolished proximal surface. Repeated radiostereometric examinations for up to two years showed a slow rate of subsidence with a mean of 0.32 mm (-2.0 to +0.31). Fifteen cases followed for a further year showed the same mean subsidence after three years, indicating stabilisation. A tendency to retroversion of the stems was noted between the operation and the last follow-up. Retroversion was also recorded when displacement of the stem was studied in ten of the patients after two years. Repeated determination of bone mineral density showed an initial loss after six months, followed by recovery to the postoperative level at two years. Defects in the cement mantle and malalignment of the stem were often noted on postoperative radiographs, but did not correlate with the degrees of migration or displacement. After one year, increasing frequency of trabecular remodelling or resorption of the graft was observed in the greater trochanter and distal to the tip of the stem. Cortical repair was noted distally and medially (Gruen regions 3, 5 and 6). Migration of the stems was the lowest reported to date, which we attribute to the improved grafting technique and to the hardness of the graft.

Ceramic coating improves tibial component fixation in total knee arthroplasty

Forty uncemented total knee arthroplasties (36 patients) were randomly allocated to a Miller-Galante II prosthesis with or without hydroxyapatite/tricalcium phosphate (HA/TCP) coating on the titanium fiber mesh on the undersurface of the tibial component. The patients were followed for 2 years with repeated radiostereometric examinations. After 2 years, the HA/TCP tibial components displayed smaller anterior-posterior tilt and less subsidence. The mean value of maximal total point motion was small: 0.5 mm in both groups. At 24 months, there were more radiolucent lines under the tibial tray and around the stem in the uncoated group, but the clinical results did not differ. HA/TCP coating on the undersurface of the tibial component improved the stability and seemed to improve the quality of the interface between the tibial component and the bone.

Identification of a fetal hematopoietic precursor with B cell, T cell, and macrophage potential

Despite years of investigation, precursor-progeny relationships within the developing lymphoid lineages of the hematopoietic system remain poorly defined. We have characterized the potential of precursors found within a subpopulation of fetal liver defined by AA4.1 and Fc gammaRII/III expression and predominantly restricted to lymphoid and macrophage development. When cultured in methylcellulose with appropriate cytokines, AA4.1+/Fc gammaR+ precursors generate colonies consisting of various lineages, including the combination of B cell, T cell, and macrophage. Retroviral marking studies showed that the lymphoid cells and macrophages within these colonies arise from a common precursor. These results demonstrate the presence of a common precursor with B cell-, T cell-, and macrophage-restricted potential and as such define an early restriction point within the fetal lymphoid system.

Expression of the LIM-homeobox gene LH2 generates immortalized steel factor-dependent multipotent hematopoietic precursors

The genes controlling self-renewal and differentiation in the hematopoietic system are largely unknown. The LIM-homeobox genes are known to be important for asymmetric cell divisions and differentiation of specific cell types and organs. One member of this family, LH2, is expressed in fetal liver at the time of active hematopoiesis. Therefore, we have assessed the function of LH2 during the formation and initial expansion of the hematopoietic system by differentiating LH2-transduced embryonic stem (ES) cells in vitro. This procedure generated multipotent hematopoietic precursor cell (HPC) lines that required Steel factor for growth. HPC lines have been maintained in an undifferentiated state in culture for >7 months. Other growth factors tested efficiently induce terminal differentiation of HPCs into various mature myeloid lineages. Steel factor is also required and acts synergistically with the other growth factors to generate multilineage colonies from the HPCs. These HPC lines express transcription factors that are consistent with an immature progenitor, and the pattern of cell surface marker expression is similar to that of early fetal multipotent hematopoietic progenitors. Collectively, these data suggest that the HPC lines represent an early fetal multipotent hematopoietic progenitor, and suggest a role for LH2 in the control of cell fate decision and/or proliferation in the hematopoietic system.

Leptin levels in protracted critical illness: effects of growth hormone-secretagogues and thyrotropin-releasing hormone

Prolonged critical illness is characterized by feeding-resistant wasting of protein, whereas reesterification, instead of oxidation of fatty acids, allows fat stores to accrue and associate with a low-activity status of the somatotropic and thyrotropic axis, which seems to be partly of hypothalamic origin. To further unravel this paradoxical metabolic condition, and in search of potential therapeutic strategies, we measured serum concentrations of leptin; studied the relationship with body mass index, insulin, cortisol, thyroid hormones, and somatomedins; and documented the effects of hypothalamic releasing factors, in particular, GH-secretagogues and TRH. Twenty adults, critically ill for several weeks and supported with normocaloric, continuously administered parenteral and/or enteral feeding, were studied for 45 h. They had been randomized to receive one of three combinations of peptide infusions, in random order: TRH (one day) and placebo (other day); TRH + GH-releasing peptide (GHRP)-2 and GHRP-2; TRH + GHRH + GHRP-2 and GHRH + GHRP-2. Peptide infusions were started after a 1-microgram/kg bolus at 0900 h and infused (1 microgram/kg.h) until 0600 h the next morning. Serum concentrations of leptin, insulin, cortisol, T4, T3, insulin-like growth factor (IGF)-I, IGF-binding protein-3 and the acid-labile subunit (ALS) were measured at 0900 h, 2100 h, and 0600 h on each of the 2 study days. Baseline leptin levels (mean +/- SEM: 12.4 +/- 2.1 micrograms/L) were independent of body mass index (25 +/- 1 kg/m2), insulin (18.6 +/- 2.9 microIU/mL), cortisol (504 +/- 43 mmol/L), and thyroid hormones (T4: 63 +/- 5 nmol/L, T3: 0.72 +/- 0.08 nmol/L) but correlated positively with circulating levels of IGF-I [86 +/- 6 micrograms/L, determination coefficient (R2) = 0.25] and ALS (7.2 +/- 0.6 mg/L, R2 = 0.32). Infusion of placebo or TRH had no effect on leptin. In contrast, GH-secretagogues elevated leptin levels within 12 h. Infusion of GHRP-2 alone induced a maximal leptin increase of +87% after 24 h, whereas GHRH + GHRP-2 elevated leptin by up to +157% after 24 h. The increase in leptin within 12 h was related (R2 = 0.58) to the substantial rise in insulin. After 45 h, and having reached a plateau, leptin was related to the increased IGF-I (R2 = 0.37). In conclusion, circulating leptin levels during protracted critical illness were linked to the activity state of the GH/IGF-I axis. Stimulating the GH/IGF-I axis with GH-secretagogues increased leptin levels within 12 h. Because leptin may stimulate oxidation of fatty acids, and because GH, IGF-I, and insulin have a protein-sparing effect, GH-secretagogue administration may be expected to result in increased utilization of fat as preferential substrate and to restore protein content in vital tissues and, consequently, has potential as a strategy to reverse the paradoxical metabolic condition of protracted critical illness.

Hormonal regulation of liver fatty acid-binding protein in vivo and in vitro: effects of growth hormone and insulin

Liver fatty acid-binding protein (LFABP) is an abundant protein in hepatocytes that binds most of the long chain fatty acids present in the cytosol. It is suggested to be of importance for fatty acid uptake and utilization in the hepatocyte. In the present study, the effects of bovine GH (bGH) and other hormones on the expression of LFABP and its messenger RNA (mRNA) were studied in hypophysectomized rats and in vitro using primary cultures of rat hepatocytes. One injection of bGH increased LFABP mRNA levels about 5-fold after 6 h, but there was no effect of this treatment on LFABP levels. However, 7 days of bGH treatment increased both LFABP mRNA and LFABP protein levels 2- to 5-fold. Female rats had higher levels of LFABP than male rats. Hypophysectomy of female rats, but not that of male rats, decreased LFABP levels markedly. Treatment of hypophysectomized rats with bGH for 7 days as two daily injections or as a continuous infusion increased LFABP levels to a similar degree. This finding indicates that the sex difference in the expression of LFABP is not regulated by the sexually dimorphic secretory pattern of GH. Neither insulin nor insulin-like growth factor I treatment of hypophysectomized rats for 6-7 days had any effect on LFABP mRNA or LFABP levels. In vitro, bGH dose-dependently increased the expression of LFABP mRNA, but only in the presence of insulin. Insulin alone had a marked dose-dependent effect on LFABP mRNA levels and was of importance for maintaining the expression of LFABP mRNA during the culture. Incubation with bGH increased LFABP mRNA levels within 3 h. GH had no effect on LFABP mRNA levels in the presence of actinomycin D, indicating a transcriptional effect of GH. Incubation with glucagon in vitro decreased LFABP mRNA levels markedly, indicating that glucagon, in contrast to GH, has an effect opposite that of insulin on LFABP mRNA expression. It is concluded that GH is an important regulator of LFABP in vivo and in vitro. In contrast to the effect of GH on insulin-like growth factor I mRNA, the presence of insulin was a prerequisite for the effect of GH on LFABP mRNA expression in vitro. The results emphasize the role of GH in the regulation of hepatic fatty acid metabolism.

Low growth hormone secretion in patients with fibromyalgia--a preliminary report on 10 patients and 10 controls

OBJECTIVE

To evaluate the secretion of growth hormone in patients with fibromyalgia (FM).

METHODS

Serum concentrations of growth hormone (24 h profiles), insulin-like growth factor I (IGF), and IGF binding protein-3 were determined in 10 women with FM and in 10 healthy controls. Quality of sleep was assessed by means of a visual analog scale.

RESULTS

Sleep was significantly more disturbed in the patients than in controls. A significantly lower secretion of growth hormone was found in the patients in comparison with healthy controls.

CONCLUSION

These results suggest that growth hormone secretion is decreased in patients with FM. Substitution therapy with low doses of growth hormone may be worth evaluating in the treatment of FM.

Biomechanical characterization of osseointegration: an experimental in vivo investigation in the beagle dog

This study reports the results of torsion tests, pull-out tests, and lateral loading tests on osseointegrated commercially pure titanium fixtures. The tests were performed in vivo on six beagle dogs. Three fixtures, each with a diameter of 3.7 mm, were installed bilaterally in the tibia of each animal. The mean maximal pull-out load was 1.55 kN (n = 4), the mean maximal lateral transverse load was 0.21 kN (n = 2), the mean maximal lateral axial load was 0.18 kN (n = 2), the mean breakpoint torque was 0.31 Nm (n = 3), and the mean maximal torque was 0.43 Nm (n = 3). The torsion test revealed an almost immediate plastic deformation of the interface between the implant and bone; this indicates that although the contact between the bone and the implant is close, there is no strong bond, at least not in shear. The major transfer of load from the implant to the surrounding bone tissue must therefore depend on the design of the implant. A histological evaluation with measurements of the amount of bone in contact with the fixtures was performed. By the use of the histological and mechanical data, it is possible to estimate shear stresses in bone tissue (pull-out test) and in the interface (torque test). The mean maximal shear stress in bone tissue in the pull-out tests was 100 MPa (n = 4); the mean shear stress in the interface was 4.3 MPa (n = 3) in the torsion tests at the breakpoint torque and was 6.0 MPa (n = 3) at the maximal torque. It was also possible to estimate the shear modulus of elasticity in the pull-out and torque tests. The mean shear modulus in pull-out was 119 MPa (n = 4), and the mean apparent shear modulus in torsion was 9 kPa (n = 3) for an assumed interface thickness of 100 nm and was 86 kPa (n = 3) for an assumed interface thickness of 1,000 nm.

Desmin is essential for the tensile strength and integrity of myofibrils but not for myogenic commitment, differentiation, and fusion of skeletal muscle

A null mutation was introduced into the mouse desmin gene by homologous recombination. The desmin knockout mice (Des -/-) develop normally and are fertile. However, defects were observed after birth in skeletal, smooth, and cardiac muscles (Li, Z., E. Colucci-Guyon, M. Pincon-Raymond, M. Mericskay, S. Pournin, D. Paulin, and C. Babinet. 1996. Dev. Biol. 175:362-366; Milner, D.J., G. Weitzer, D. Tran, A. Bradley, and Y. Capetanaki. 1996. J. Cell Biol. 134:1255- 1270). In the present study we have carried out a detailed analysis of somitogenesis, muscle formation, maturation, degeneration, and regeneration in Des -/- mice. Our results demonstrate that all early stages of muscle differentiation and cell fusion occur normally. However, after birth, modifications were observed essentially in weight-bearing muscles such as the soleus or continually used muscles such as the diaphragm and the heart. In the absence of desmin, mice were weaker and fatigued more easily. The lack of desmin renders these fibers more susceptible to damage during contraction. We observed a process of degeneration of myofibers, accompanied by macrophage infiltration, and followed by a process of regeneration. These cycles of degeneration and regeneration resulted in a relative increase in slow myosin heavy chain (MHC) and decrease in fast MHC. Interestingly, this second wave of myofibrillogenesis during regeneration was often aberrant and showed signs of disorganization. Subsarcolemmal accumulation of mitochondria were also observed in these muscles. The lack of desmin was not compensated by an upregulation of vimentin in these mice either during development or regeneration. Absence of desmin filaments within the sarcomere does not interfere with primary muscle formation or regeneration. However, myofibrillogenesis in regenerating fibers is often abortive, indicating that desmin may be implicated in this repair process. The results presented here show that desmin is essential to maintain the structural integrity of highly solicited skeletal muscle.

Clinical and radiologic survivorship of cementless tibial components fixed with finned polyethylene pegs

One hundred twenty patients (22 men, 98 women; 144 knees) with uncemented Freeman-Samuelson total knee arthroplasty were followed prospectively. Eighty-one patients had rheumatoid arthritis and 39 patients had osteoarthrosis. The mean follow-up period was 6.8 years. Three different types of tibial components were used: a high-density polyethylene component without stem, a metal-backed tibial component without stem, and a metal-backed tibial component with stem. Progressive varus tilting turned out to be an early sign of failure and occurred in 22% of the tibial components. Revision of the tibial component was done in 17 knees. Survival analysis with revision as endpoint revealed a survival rate of 79% at a follow-up period of 10 years. Cementless fixation of this design using macrointerlocking pegs and no other stabilization resulted in poor fixation and a high revision rate and cannot be recommended.