Computational study of extrinsic factors affecting ACL strain during single-leg jump landing

BACKGROUND

Non-contact anterior cruciate ligament (ACL) injuries are a major concern in sport-related activities due to dynamic knee movements. There is a paucity of finite element (FE) studies that have accurately replicated the knee geometry, kinematics, and muscle forces during dynamic activities. The objective of this study was to develop and validate a knee FE model and use it to quantify the relationships between sagittal plane knee kinematics, kinetics and the resulting ACL strain.

METHODS

3D images of a cadaver knee specimen were segmented (bones, cartilage, and meniscus) and meshed to develop the FE model. Knee ligament insertion sites were defined in the FE model via experimental digitization of the specimen's ligaments. The response of the model was validated against multiple physiological knee movements using published experimental data. Single-leg jump landing motions were then simulated on the validated model with muscle forces and kinematic inputs derived from motion capture and rigid body modelling of ten participants.

RESULTS

The maximum ACL strain measured with the model during jump landing was 3.5 ± 2.2%, comparable to published experimental results. Bivariate analysis showed no significant correlation between body weight, ground reaction force and sagittal plane parameters (such as joint flexion angles, joint moments, muscle forces, and joint velocity) and ACL strain. Multivariate regression analysis showed increasing trunk, hip and ankle flexion angles decreases ACL strain (R2 = 90.04%, p < 0.05).

CONCLUSIONS

Soft landing decreases ACL strain and the relationship could be presented through an empirical equation. The model and the empirical relation developed in this study could be used to better predict ACL injury risk and prevention strategies during dynamic activities.

The effects of pistol grip power tools on median nerve pressure and tendon strains

Objectives. Tendonitis and carpal tunnel syndrome are common cumulative trauma disorders that can occur with repetitive usage of pistol grip power tools. The role of reaction torque resulting in a forceful rotary displacement of the tool handle, as well as the role of applied grip force, is not clear in the development of these disorders. This study aimed to quantify the flexor tendon strains and median nerve pressure during a typical power tool operation securing a threaded fastener. Methods. Six fresh-frozen cadaver arms were made to grip a replica pistol grip power tool using static weights to apply muscle forces. A 5-Nm torque was applied to the replica power tool. The median nerve pressure and strains in the flexor digitorum profundus and superficialis tendons were measured using a catheter and strain gauges, at three wrist flexion angles. Results. The peak tendon strains were between 1.5 and 2% and were predominantly due to the grip force more than the transmitted torque. Median nerve pressure significantly increased with the wrist flexed versus extended. Conclusion. The results indicate that the contribution of the grip force to the tendon strain and median nerve pressure was greater than the contribution from the reaction torque.

AB0930 URATE INDUCED PRIMING OF HUMAN MONOCYTES IS MEDIATED VIA THE TGF-Β PATHWAY

Background:

Hyperuricemia, elevated serum urate levels, is the main risk factor for gout, but is also associated with higher incidence of comorbidities such as cardiovascular disease, type 2 diabetes, metabolic syndrome and chronic kidney disease[1]. Crisanet al.showed that urate leads to increased production of interleukin (IL)-1β, a pro-inflammatory cytokine, and downregulation of IL-1 receptor antagonist (IL-1Ra), the natural inhibitor of IL-1, in human monocytes[2]. This imbalance between IL-1β and IL-1Ra is mediated by epigenetic reprogramming of innate immune cells[2]. RNA sequencing in urate-treated monocytes demonstrated that the TGF-β signalling pathway was differentially expressed[3].

Objectives:

The objective of this study is to further explore the role of TGF-β in urate induced priming of human monocytes.

Methods:

Human peripheral blood mononuclear cells (PBMCs) were isolated from healthy volunteers, adhered to a flat bottom plate, and treated for 24h with a dosing range of urate after which mRNA was isolated. For validation experiments, PBMCs from 9 gout patients and 7 healthy controls were isolated and adhered to a flat bottom plate for 4h after which cells were stored for RNA isolation. qPCR primers designed for TGF-β, TGF-β receptor I and II, MMP9, SMAD7 and ITGAV were used to assess expression levels of TGF-β pathway in these adherent monocytes. For priming experiments, adherent monocytes were primed for 24h with urate and/or recombinant TGF-β1 (R&D systems) with or without a TGF-β receptor II antibody (R&D systems), cells were washed and restimulated with LPS for 24h. Cytokine levels in supernatant were determined by ELISA for IL-1β, IL-6 and IL-1Ra.

Results:

mRNA expression of TGF-β and its downstream targets were upregulated in urate treated monocytes and in gout patients compared to healthy controls. Moreover, urate levels significantly correlated to TGF-β in individuals with gout. Both urate and TGF-β priming increased the release of IL-1β and IL-6 after LPS stimulation in human monocytes. We did not observe a synergistic effect between the two and therefore hypothesized that urate induced inflammation is mediated via TGF-β. Blocking the TGF-β receptor II partly reversed the urate induced phenotype: lowered IL-1β and IL-6 production and restored levels of IL-1Ra. Further validation experiments are ongoing.

Conclusion:

Urate induced priming of human monocytes is at least partly mediated via the TGF-β pathway. This study contributes to the understanding of the pathways involved in urate induced inflammatory status and might in the future provide a mechanistic explanation for the occurrence of some comorbidities in patients with gout. Additionally, as TGF-β is a major player in the pathogenesis of systemic sclerosis, this study might give a rationale for treatment of hyperuricemia in this population.

References:

[1]Bardin, T. and P. Richette,Impact of comorbidities on gout and hyperuricaemia: an update on prevalence and treatment options.BMC Med, 2017.15(1): p. 123.

[2]Crisan, T.O., et al.,Soluble uric acid primes TLR-induced proinflammatory cytokine production by human primary cells via inhibition of IL-1Ra.Ann Rheum Dis, 2016.75(4): p. 755-62.

[3]Crisan, T.O., et al.,Uric acid priming in human monocytes is driven by the AKT-PRAS40 autophagy pathway.Proc Natl Acad Sci U S A, 2017.114(21): p. 5485-5490.

Disclosure of Interests:

Viola Klück: None declared, Linda Mies: None declared, René Bakker: None declared, Tania Crisan: None declared, Leo Joosten Consultant of: SAB member of Olatec Therapeutics LLC

The effect of unloader knee braces on medial meniscal strain

BACKGROUND:

A medial meniscal tear is a common knee injury, especially following an anterior cruciate ligament injury. Decreasing the compressive force on the medial meniscus during dynamic activities using an unloader knee brace could reduce meniscal strain, effectively reducing injury risk and/or severity.

OBJECTIVES:

To investigate the efficacy of two unloader knee braces on medial meniscus strain during dynamic activities in intact & deficient anterior cruciate ligament states.

STUDY DESIGN:

Combined in vivo/in vitro study.

METHODS:

In vivo knee kinematics and muscle force profiles from a healthy individual performing single/doubleleg squats and walking motions were simulated on 10 cadaveric specimens using a dynamic knee simulator system. Simulations were performed on knees in unbraced and braced scenarios, with and without the anterior cruciate ligament. Anterior and posterior medial meniscal strains were measured.

RESULTS:

Two different braces each showed a significant reduction in the posteromedial meniscal strain ( p ⩽ 0.01) in an intact anterior cruciate ligament state. Neither brace mirrored this result for the anteromedial strain ( p > 0.05). In the deficient anterior cruciate ligament state, the braces had no significant effect on strain ( p > 0.05).

CONCLUSION:

Two unloader knee braces effectively reduced strain in the medial meniscus with an intact anterior cruciate ligament during dynamic activities. Neither brace made a significant reduction in strain for anterior cruciate ligament-deficient knees.

CLINICAL RELEVANCE

Unloader knee braces could be used to reduce the medial meniscus strain following meniscal surgery and during rehabilitation in patients with an isolated medial meniscus injury. However, these braces cannot be recommended for this purpose in patients with an anterior cruciate ligament deficiency.

Dynamically tensioned ACL functional knee braces reduce ACL and meniscal strain

PURPOSE

The effectiveness of ACL functional knee braces to reduce meniscal and ACL strain after ACL injury or reconstruction is not well understood. A new dynamic knee tensioning brace system has been designed to apply an active stabilizing force to the knee. The ability of this system to reduce tissue strains is unknown. The purpose of this study was to test the ability of the dynamically tensioned brace to reduce strain in both the ACL and meniscus during rehabilitation activities.

METHODS

A combined in vivo/in silico/in vitro method was used to study three activities: gait, double leg squat, and single leg squat. Muscle forces and kinematics for each activity were derived through in vivo motion capture and applied to seven cadaveric knee specimens fitted with custom braces. Medial meniscal strain and ACL strain were measured in ACL intact, deficient and reconstructed conditions.

RESULTS

The brace lowered peak and average meniscal strain in ACL deficient knees (P < 0.05) by an average of 1.7%. The brace was also found to lower meniscal strain in reconstructed knees (1.1%) and lower ACL strain in ACL intact (1.3%) and reconstructed knees (1.4%) (P < 0.05).

CONCLUSIONS

This study supports the use of a brace equipped with a dynamic tensioning system to lower meniscal strain in ACL-deficient knees. Its use may help decrease the risk of subsequent meniscal tears in chronic ACL deficiency or delayed reconstruction. In ACL-intact and reconstructed knees, the brace may be beneficial in injury prophylaxis or in protecting the ACL graft following reconstruction. These results will aid clinicians make informed recommendations for functional brace use in patients with unstable knees.

LEVEL OF EVIDENCE

II.

New Adjustable Unloader Knee Brace and Its Effectiveness

Unloader knee braces are prescribed for patients with unicompartmental osteoarthritis of the knee. These braces aim to reduce pain in patients by applying a coronal moment to the knee to unload the symptomatic knee compartment. However, existing unloading mechanisms use straps that go directly behind the knee joint, to apply the needed moment. This can impinge on the popliteal artery and peroneal nerves thereby causing discomfort to the patient. Hence, these braces cannot be worn for prolonged periods of time. This research focused on developing a new knee brace to improve comfort while unloading the osteoarthritic knee. A new knee brace was developed that uses a four-point bending approach to unload the knee. In this brace, unloading can be adjusted, and the unloading mechanism is away from the joint. The new brace was tested on a cadaver specimen to quantify its capability to unload the knee compartment. The brace was also worn by a patient with osteoarthritis who subjectively compared it to his existing unloader brace. During cadaver testing, the new brace design could reduce the force exerted on the medial condyle by 25%. Radiographic images of the patient's knee confirmed that the brace unloaded the medial condyle successfully. The patient reported that the new brace reduced pain, was significantly comfortable to wear and could be used for a longer duration in comparison to his existing brace.

Effect of sagittal plane mechanics on ACL strain during jump landing

The relationships between non-contact anterior cruciate ligament injuries and the underlying biomechanics are still unclear, despite large quantities of academic research. The purpose of this research was to study anterior cruciate ligament strain during jump landing by investigating its correlation with sagittal plane kinetic/kinematic parameters and by creating an empirical model to estimate the maximum strain. Whole-body kinematics and ground reaction forces were measured from seven subjects performing single leg jump landing and were used to drive a musculoskeletal model that estimated lower limb muscle forces. These muscle forces and kinematics were then applied on five instrumented cadaver knees using a dynamic knee simulator system. Correlation analysis revealed that higher ground reaction force, lower hip flexion angle and higher hip extension moment among others were correlated with higher peak strain (p < 0.05). Multivariate regression analyses revealed that intrinsic anatomic factors account for most of the variance in strain. Among the extrinsic variables, hip and trunk flexion angles significantly contributed to the strain. The empirical relationship developed in this study could be used to predict the relative strain between jumps of a participant and may be beneficial in developing training programs designed to reduce an athlete's risk of injury. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1636-1644, 2016.

Can a knee brace reduce the strain in the anterior cruciate ligament? A study using combined in vivo/in vitro method

BACKGROUND AND AIM

It is unknown whether prophylactic knee braces can reduce the strain in the anterior cruciate ligament during dynamic activities.

TECHNIQUE

An athlete, who had characteristics of high anterior cruciate ligament injury risk, was chosen. A motion capture system (Optotrak Certus; Northern Digital, Waterloo, ON, Canada) was used to record dynamic trials during drop-landing activity of this subject with and without the knee brace being worn. A musculoskeletal model was used to estimate the muscle forces during this activity. A dynamic knee simulator then applied kinematics and muscle forces on a cadaver knee with and without the brace mounted on it. The anterior cruciate ligament strain was measured.

DISCUSSION

The peak strain in the anterior cruciate ligament was substantially lower for the braced (7%) versus unbraced (20%) conditions. Functional knee braces could decrease the strain in the anterior cruciate ligament during dynamic activities in a high-risk subject. However, the reduction seems to be a result of altered muscle firing pattern due to the brace.

CLINICAL RELEVANCE

Prophylactic knee brace could reduce the strain in the anterior cruciate ligament of high-risk subjects during drop-landing through altered muscle firing pattern associated with brace wear. This could help reduce the anterior cruciate ligament injury risk.

Bridging between professionals in perinatal care: towards shared care in the Netherlands

Relatively high perinatal mortality rates in the Netherlands have required a critical assessment of the national obstetric system. Policy evaluations emphasized the need for organizational improvement, in particular closer collaboration between community midwives and obstetric caregivers in hospitals. The leveled care system that is currently in place, in which professionals in midwifery and obstetrics work autonomously, does not fully meet the needs of pregnant women, especially women with an accumulation of non-medical risk factors. This article provides an overview of the advantages of greater interdisciplinary collaboration and the current policy developments in obstetric care in the Netherlands. In line with these developments we present a model for shared care embedded in local 'obstetric collaborations'. These collaborations are formed by obstetric caregivers of a single hospital and all surrounding community midwives. Through a broad literature search, practical elements from shared care approaches in other fields of medicine that would suit the Dutch obstetric system were selected. These elements, focusing on continuity of care, patient centeredness and interprofessional teamwork form a comprehensive model for a shared care approach. By means of this overview paper and the presented model, we add direction to the current policy debate on the development of obstetrics in the Netherlands. This model will be used as a starting point for the pilot-implementation of a shared care approach in the 'obstetric collaborations', using feedback from the field to further improve it.

Dose-response relationship between alcohol consumption before and during pregnancy and the risks of low birthweight, preterm birth and small for gestational age (SGA)-a systematic review and meta-analyses

BACKGROUND

Descriptions of the effects of moderate alcohol consumption during pregnancy on adverse pregnancy outcomes have been inconsistent.

OBJECTIVE

To review systematically and perform meta-analyses on the effect of maternal alcohol exposure on the risk of low birthweight, preterm birth and small for gestational age (SGA).

SEARCH STRATEGY

Using Medical Subject Headings, a literature search of MEDLINE, EMBASE, CINAHL, CABS, WHOlist, SIGLE, ETOH, and Web of Science between 1 January 1980 and 1 August 2009 was performed followed by manual searches.

SELECTION CRITERIA

Case-control or cohort studies were assessed for quality (STROBE), 36 available studies were included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted the information on low birthweight, preterm birth and SGA using a standardised protocol. Meta-analyses on dose-response relationships were performed using linear as well as first-order and second-order fractional polynomial regressions to estimate best fitting curves to the data.

MAIN RESULTS

Compared with abstainers, the overall dose-response relationships for low birthweight and SGA showed no effect up to 10 g pure alcohol/day (an average of about 1 drink/day) and preterm birth showed no effect up to 18 g pure alcohol/day (an average of 1.5 drinks/day); thereafter, the relationship showed a monotonically increasing risk for increasing maternal alcohol consumption. Moderate consumption during pre-pregnancy was associated with reduced risks for all outcomes.

CONCLUSIONS

Dose-response relationship indicates that heavy alcohol consumption during pregnancy increases the risks of all three outcomes whereas light to moderate alcohol consumption shows no effect. Preventive measures during antenatal consultations should be initiated.

Clinical differentiation between acute appendicitis and acute mesenteric lymphadenitis in children

INTRODUCTION

Acute mesenteric lymphadenitis in children has a clinical presentation very similar to that of acute appendicitis. The aim of this study was to evaluate whether it is possible to clinically differentiate between acute appendicitis and acute mesenteric lymphadenitis in children.

METHODS

A prospective cohort analysis was performed for all children (<17 years) presenting to the emergency department of our institution with acute abdominal pain between June 2005 and July 2006. The relevant clinical parameters, clinical and radiological diagnoses and all management decisions were scored prospectively. Ultrasound was the primary imaging modality for the majority of patients. All patients were re-evaluated until a final diagnosis was attained. The Alvarado score was calculated retrospectively, and a logistic regression model was used to analyze the diagnostic potential of clinical parameters.

RESULTS

289 patients were eligible for analysis. 38 patients had acute mesenteric lymphadenitis, and 69 patients had acute appendicitis as a final diagnosis. The positive predictive values of the clinical diagnosis, the Alvarado score and the logistic regression model were 0.62, 0.81 and 0.79 respectively. Ultrasound had a positive predictive value of 96% for acute appendicitis.

CONCLUSION

It is not possible to accurately distinguish acute mesenteric lymphadenitis from acute appendicitis in children using clinical evaluation alone. Ultrasound should be performed in equivocal cases.

Effects of C60 nanoparticle exposure on earthworms (Lumbricus rubellus) and implications for population dynamics

Effects of C60 nanoparticles (nominal concentrations 0, 15.4 and 154 mg/kg soil) on mortality, growth and reproduction of Lumbricus rubellus earthworms were assessed. C60 exposure had a significant effect on cocoon production, juvenile growth rate and mortality. These endpoints were used to model effects on the population level. This demonstrated reduced population growth rate with increasing C60 concentrations. Furthermore, a shift in stage structure was shown for C60 exposed populations, i.e. a larger proportion of juveniles. This result implies that the lower juvenile growth rate due to exposure to C60 resulted in a larger proportion of juveniles, despite increased mortality among juveniles. Overall, this study indicates that C60 exposure may seriously affect earthworm populations. Furthermore, it was demonstrated that juveniles were more sensitive to C60 exposure than adults.

Toxicity of homologous series of organic solvents for the gram-positive bacteria Arthrobacter and Nocardia Sp. and the gram-negative bacteria Acinetobacter and Pseudomonas Sp

The toxicity of homologous series of organic solvents has been investigated for the gram-positive bacteria, Arthrobacter sp. and Nocardia sp., and the gram-negative bacteria, Acinetobacter sp. and Pseudomonas sp. The hydrophobicity of the solvent, expressed by its logP(octanol), proves to be a good measure for the toxicity of solvents in a two-phase system. The transition from toxic to nontoxic solvents occurs between logP(octanol) 3 and 5 and depends on the homologous series. No correlation has been found between the hydrophobicity of the substituent on the alkyl backbone of the solvent and the location of the transition point in toxicity. The logP(octanol), above which all solvents are nontoxic, is used to express the solvent tolerance of the bacteria. In general, the solvent tolerance of gram-negative bacteria is found to be slightly higher than that of gram-positive bacteria, but this does not hold for all homologous series of organic solvents investigated.Because the toxicity effects of organic solvents in a two-phase system can be ascribed to molecular as well as phase toxicity effects, molecular toxicity effects were investigated separately in a one-phase system with subsaturating amounts of organic solvent. The solvent concentration in the aqueous phase, at which 50% of the metabolic activity of the bacteria is lost, is used to express solvent toxicity. This concentration is found to be similar for the gram-positive Arthrobacter and the gram-negative Acinetobacter. Assuming the critical membrane concentration theory (G. J. Osborne et al. Enzyme Microb. Technol. 1990, 12: 281-291) to be valid, it can be concluded that differences in solvent tolerance between these two bacteria, cannot be ascribed to differences in response to molecular toxicity. Prediction of the toxicity of any solvent, using the critical membrane theory, appears to be possible in the case of alkanols or alkyl acetates. However, prediction of the toxicity of ethers appears to be impossible.

Demonstration of a spaser-based nanolaser

One of the most rapidly growing areas of physics and nanotechnology focuses on plasmonic effects on the nanometre scale, with possible applications ranging from sensing and biomedicine to imaging and information technology. However, the full development of nanoplasmonics is hindered by the lack of devices that can generate coherent plasmonic fields. It has been proposed that in the same way as a laser generates stimulated emission of coherent photons, a 'spaser' could generate stimulated emission of surface plasmons (oscillations of free electrons in metallic nanostructures) in resonating metallic nanostructures adjacent to a gain medium. But attempts to realize a spaser face the challenge of absorption loss in metal, which is particularly strong at optical frequencies. The suggestion to compensate loss by optical gain in localized and propagating surface plasmons has been implemented recently and even allowed the amplification of propagating surface plasmons in open paths. Still, these experiments and the reported enhancement of the stimulated emission of dye molecules in the presence of metallic nanoparticles lack the feedback mechanism present in a spaser. Here we show that 44-nm-diameter nanoparticles with a gold core and dye-doped silica shell allow us to completely overcome the loss of localized surface plasmons by gain and realize a spaser. And in accord with the notion that only surface plasmon resonances are capable of squeezing optical frequency oscillations into a nanoscopic cavity to enable a true nanolaser, we show that outcoupling of surface plasmon oscillations to photonic modes at a wavelength of 531 nm makes our system the smallest nanolaser reported to date-and to our knowledge the first operating at visible wavelengths. We anticipate that now it has been realized experimentally, the spaser will advance our fundamental understanding of nanoplasmonics and the development of practical applications.

Population-level effect of HSV-2 therapy on the incidence of HIV in sub-Saharan Africa

BACKGROUND

Herpes simplex virus type 2 (HSV-2) infection increases acquisition and transmission of HIV, but the results of trials measuring the impact of HSV-2 therapy on HIV genital shedding and HIV acquisition are mixed, and the potential impact of HSV-2 therapy on the incidence of HIV at the population level is unknown.

METHODS

The effects of episodic and suppressive HSV-2 therapy were simulated using the individual-level model STDSIM fitted to data from Cotonou, Benin (relatively low HIV prevalence) and Kisumu, Kenya (high HIV prevalence). Clinician- and patient-initiated episodic therapy, started when symptomatic, were assumed to reduce ulcer duration. Suppressive therapy, given regardless of symptoms, was also assumed to reduce ulcer frequency and HSV-2 infectiousness.

RESULTS

Clinician-initiated episodic therapy in the general population had almost no effect on the incidence of HIV. The impact of patient-initiated therapy was higher because of earlier treatment initiation, but still low (<5%) unless symptom recognition and treatment-seeking behaviour were very high. Suppressive therapy given to female sex workers (FSW) in Kisumu had little effect on population HIV incidence. In Cotonou, suppressive therapy in FSW with high coverage and long duration reduced population HIV incidence by >20% in the long term. Impact was increased in both cities by also treating a proportion of their clients. Long-term suppressive therapy with high coverage in the general population could reduce HIV incidence by more than 30%.

CONCLUSIONS

These results show that HSV-2 therapy could potentially have a population-level impact on the incidence of HIV, especially in more concentrated epidemics. However, a substantial impact requires high coverage and long duration therapy, or very high symptom recognition and treatment-seeking behaviour.

Behaviour change and competitive exclusion can explain the diverging HIV-1 and HIV-2 prevalence trends in Guinea-Bissau

The aim of this study was to determine whether a temporary rise in sexual risk behaviour during war in Guinea-Bissau could explain the observed trends in HIV-1 and HIV-2 prevalence, and to explore the possible contribution of competitive elimination of HIV-2 by HIV-1. A simulation model of the heterosexual transmission of sexually transmitted infections was parameterized using demographic, behavioural and epidemiological data from rural Guinea-Bissau, and fitted to the observed HIV-1 and HIV-2 trends with and without a historic rise in risk behaviour. The observed trends could only be simulated by assuming a temporary rise in risk behaviour. Around 30% of the projected decline in HIV-2 prevalence from a peak of 8.7% to 4.3% in 2010 was due to competitive elimination by HIV-1. Importantly for public health, HIV-1 prevalence was predicted to continue increasing and to become the dominant HIV type by 2010. Data collection is required to validate this prediction.

Laser-photofield emission from needle cathodes for low-emittance electron beams

Illumination of a ZrC needle with short laser pulses (16 ps, 266 nm) while high voltage pulses (-60 kV, 2 ns, 30 Hz) are applied, produces photo-field emitted electron bunches. The electric field is high and varies rapidly over the needle surface so that quantum efficiency (QE) near the apex can be much higher than for a flat photocathode due to the Schottky effect. Up to 150 pC (2.9 A peak current) have been extracted by photo-field emission from a ZrC needle. The effective emitting area has an estimated radius below 50 microm leading to a theoretical intrinsic emittance below 0.05 mm mrad.

Reference Histology of Veal Calf Genital and Endocrine Tissues ? An Update for Screening on Hormonal Growth Promoters

An animal experiment has been performed with 42 veal calves, 21 males and 21 females, which were fed and housed according to European regulations for veal calves. The animals were kept in six groups of seven animals and fed milk replacer supplemented with three different levels of lactulose (0%, 1% and 3%) and some roughage. At the start of the experiment the animals were 1-3 weeks of age and they were slaughtered at 26 weeks. From male animals prostate, bulbo-urethal gland and testes were sampled, from female animals Bartholin's gland, uterus, cervix and ovaries were sampled. From all animals thyroid, thymus, adrenals, liver and kidneys were sampled. Histological investigation of the prostates and bulbo-urethral glands showed normal histology. This means that dilated tubules, strong secretion, increased mucinous glandular tissue and severe hyperplasia and squamous metaplasia, as is regularly observed in practice in the Netherlands, were not present in these animals. None of these prostates would be judged as positive in the screening for hormones as is performed by the Dutch Food and Consumer Product Safety Authority (VWA). The female calves also showed normal histology of Bartholin's gland except for three animals that appeared to be in oestrus and showed some metaplasie of the ducts but with a normal gland to duct ratio. These animals would be judged as suspect. The liver and kidney showed minor alterations due to slight infections during the experimental period. This experiment showed that it is possible to raise veal calves according to the practice without getting positive histology in the prostate or Bartholin's gland.

Simultaneous quantification of differently glycosylated, acetylated, and 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one-conjugated soyasaponins using reversed-phase high-performance liquid chromatography with evaporative light scattering detection

A novel method utilizing high-performance liquid chromatography (HPLC) with evaporative light scattering detection (ELSD) and electrospray ionisation mass spectrometry (ESI-MS) was developed for the analysis of soyasaponins, a divers group of triterpenic compounds with one or two sugar side chains, occurring in soy. Group A soyasaponins in different degrees of acetylation, as well as group B soyasaponins in both their 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP)-conjugated and non-conjugated forms could be separated and quantified using authentic soyasaponin standards, in one single run. The method was tested by the determination of the soyasaponin content and composition of eight soygerm samples of different origin. Differences in the composition and the degree of acetylation of the group A soyasaponins were observed among these samples. The group B soyasaponins showed much less variability and they were mainly present in their DDMP-conjugated form.

Determinants of the impact of sexually transmitted infection treatment on prevention of HIV infection: a synthesis of evidence from the Mwanza, Rakai, and Masaka intervention trials

Community-randomized trials in Mwanza, Tanzania, and Rakai and Masaka, Uganda, suggested that population characteristics were an important determinant of the impact of sexually transmitted infection (STI) treatment interventions on incidence of human immunodeficiency virus (HIV) infection. We performed simulation modeling of HIV and STI transmission, which confirmed that the low trial impact in Rakai and Masaka could be explained by low prevalences of curable STI resulting from lower-risk sexual behavior in Uganda. The mature HIV epidemics in Uganda, with most HIV transmission occurring outside core groups with high STI rates, also contributed to the low impact on HIV incidence. Simulated impact on HIV was much greater in Mwanza, although the observed impact was larger than predicted from STI reductions, suggesting that random error also may have played some role. Of proposed alternative explanations, increasing herpetic ulceration due to HIV-related immunosuppression contributed little to the diminishing impact of antibiotic treatment during the Ugandan epidemics. The strategy of STI treatment also was unimportant, since syndromic treatment and annual mass treatment showed similar effectiveness in simulations of each trial population. In conclusion, lower-risk behavior and the mature HIV epidemic explain the limited impact of STI treatment on HIV incidence in Uganda in the 1990s. In populations with high-risk sexual behavior and high STI rates, STIs treatment interventions may contribute substantially to prevention of HIV infection.

Reduced oocyte activation and first cleavage rate after ICSI with spermatozoa from a sterile mouse chromosome mutant

BACKGROUND

Male mice, heterozygous for two semi-identical reciprocal translocations T(1;13)70H and T(1;13)1Wa are usually sterile. We have investigated this oligoasthenoteratozoospermic mouse model using ICSI.

METHODS

B6D2F1 oocytes were injected with epididymal or testicular sperm from fertile or sterile translocation carriers and from chromosomally normal fertile controls. ICSI efficiency was determined by pronucleus formation and first cleavage rates. For arrested zygotes, cell cycle progression was evaluated by BrdU incorporation and incubation with okadaic acid.

RESULTS

Epididymal sperm from infertile translocation carriers showed a slightly lower fertilization rate (70% vs. 92%, 95% and 95% for fertile translocation carriers and two groups of normal fertile control males, respectively) and a severely reduced cleavage rate (33% vs. 87%, 96% and 89% for the same control groups). However, the use of testicular sperm significantly improved the cleavage rate (62% vs. 83% for normal fertile controls). Development of arrested zygotes was delayed or blocked during S- and G2-phase.

CONCLUSIONS

Whereas control testicular and epididymal sperm performed equally well, the use of testicular sperm from oligospermic T/T' males significantly increased first cleavage rates when compared to the low rates with epididymal sperm. Epididymal storage in oligospermics may negatively influence zygote division.

The effect of HIV, behavioural change, and STD syndromic management on STD epidemiology in sub-Saharan Africa: simulations of Uganda

An assessment was made of how the HIV epidemic may have influenced sexually transmitted disease (STD) epidemiology in Uganda, and how HIV would affect the effectiveness of syndromic STD treatment programmes during different stages of the epidemic. The dynamic transmission model STDSIM was used to simulate the spread of HIV and four bacterial and one viral STD. Model parameters were quantified using demographic, behavioural, and epidemiological data from rural Rakai and other Ugandan populations. The findings suggest that severe HIV epidemics can markedly alter STD epidemiology, especially if accompanied by a behavioural response. Likely declines in bacterial causes of genital ulcers should be considered in defining policies on syndromic STD management in severe HIV epidemics.

Focusing strategies of condom use against HIV in different behavioural settings: an evaluation based on a simulation model

Using a sexually transmitted diseases simulation model (STDSIM), we made projections of HIV spread for four profiles of sexual behaviour reflecting patterns encountered across the developing world: 1) much commercial sex, no short relationships; 2) commercial sex, concurrent short relationships; 3) concurrent relationships, no commercial sex; 4) serial short relationships, some commercial sex. We studied the effects of increasing condom use in three target groups: commercial sex workers (CSWs); men engaging in commercial contacts and short relationships; and females in steady relationships. The projections indicated that the CSW and male strategies were more effective in reducing HIV incidence than the strategy focusing on females in steady relationships. In the long run, even the group of men and women with one recent partner were better protected against HIV infection by condom use in high-risk contacts than by condom use in steady relationships. Furthermore, the numbers of HIV cases prevented per condom used were 7 to 500 times higher for condoms used by CSWs or men engaging in short relationships and commercial sex than for ones used by females in steady relationships. The results indicated the merit of focusing on high-risk groups irrespective of the pattern of sexual behaviour, even in epidemics that had already spread throughout populations.

Learning chaotic attractors by neural networks

An algorithm is introduced that trains a neural network to identify chaotic dynamics from a single measured time series. During training, the algorithm learns to short-term predict the time series. At the same time a criterion, developed by Diks, van Zwet, Takens, and de Goede (1996) is monitored that tests the hypothesis that the reconstructed attractors of model-generated and measured data are the same. Training is stopped when the prediction error is low and the model passes this test. Two other features of the algorithm are (1) the way the state of the system, consisting of delays from the time series, has its dimension reduced by weighted principal component analysis data reduction, and (2) the user-adjustable prediction horizon obtained by "error propagation"-partially propagating prediction errors to the next time step. The algorithm is first applied to data from an experimental-driven chaotic pendulum, of which two of the three state variables are known. This is a comprehensive example that shows how well the Diks test can distinguish between slightly different attractors. Second, the algorithm is applied to the same problem, but now one of the two known state variables is ignored. Finally, we present a model for the laser data from the Santa Fe time-series competition (set A). It is the first model for these data that is not only useful for short-term predictions but also generates time series with similar chaotic characteristics as the measured data.

Mutational spectrum of the TSC1 gene in a cohort of 225 tuberous sclerosis complex patients: no evidence for genotype-phenotype correlation

Tuberous sclerosis complex is an inherited tumour suppressor syndrome, caused by a mutation in either the TSC1 or TSC2 gene. The disease is characterised by a broad phenotypic spectrum that can include seizures, mental retardation, renal dysfunction, and dermatological abnormalities. The TSC1 gene was recently identified and has 23 exons, spanning 45 kb of genomic DNA, and encoding an 8.6 kb mRNA. After screening all 21 coding exons in our collection of 225 unrelated patients, only 29 small mutations were detected, suggesting that TSC1 mutations are under-represented among TSC patients. Almost all TSC1 mutations were small changes leading to a truncated protein, except for a splice site mutation and two in frame deletions in exon 7 and exon 15. No clear difference was observed in the clinical phenotype of patients with an in frame deletion or a frameshift or nonsense mutation. We found the disease causing mutation in 13% of our unrelated set of TSC patients, with more than half of the mutations clustered in exons 15 and 17, and no obvious under-representation of mutations among sporadic cases. In conclusion, we find no support for a genotype-phenotype correlation for the group of TSC1 patients compared to the overall population of TSC patients.

Genetic analysis of dystrophic cardiac calcification in DBA/2 mice

A DBA/2 x D2B6F1 backcross was produced in order to study the genetic background of pathological soft tissue calcification in the mouse. Calcification was assessed in the myocardium, kidney and tongue. Significant co-segregation was found with the genotype of microsatellite markers on the proximal end of Chromosome 7. This region contains a candidate gene, Hrc, coding for the histidine-rich calcium binding protein in the sarcoplasmatic reticulum. The results support the hypothesis that the gene previously reported to be responsible for DCC (dystrophic cardiac calcification) in C3H mice (1) causes generalized soft tissue calcification in DBA/2 mice.

Evaluation of the iron status of the newborn by soluble transferrin receptors in serum

The concentration of soluble transferrin receptors in serum has proven to be a reliable predictor of iron status in adults. Its high sensitivity for iron deficiency combined with a small sample size (10 microliters) makes it an interesting parameter for the assessment of iron stores in newborn infants. In the present study we investigated the usefulness of the concentration of soluble transferrin receptors in serum in the assessment of iron metabolism in the newborn. Infants born after an uncomplicated labour were compared to infants in the intensive care unit. The concentration of soluble transferrin receptors in serum was found to be elevated compared to normal adults and independently of iron metabolism. The concentration of soluble transferrin receptors did not correlate with serum iron and ferritin concentrations. In contrast to what was found in other studies, no relationship could be demonstrated between soluble transferrin receptors and birth weight or gestational age. The results of this study have shown that care has to be taken in the interpretation of the concentration of soluble transferrin receptors in serum in newborn infants. It seems to be a parameter which is independent of iron metabolism at least during the first days of life.

The chloride conductance of tight junctions of rat ileum can be increased by cAMP but not by carbachol

It is well known, that in mammalian small intestine, cAMP increases Cl- permeability of the apical membrane of enterocytes as part of its secretory action. Paradoxically, this is usually accompanied by an increase of the transepithelial resistance. In the present study we report that in the presence of bumetanide (to block basolateral Cl- uptake) cAMP always decreased the transepithelial resistance. We examined whether this decrease in resistance was due to a cAMP-dependent increase of the paracellular electrolyte permeability in addition to the increase of the Cl- permeability of the apical cell membrane. We used diffusion potentials induced by serosal replacement of NaCl, and transepithelial current passage to evoke transport number effects. The results revealed that cAMP (but not carbachol) could increase the Cl- permeability of the tight junctions in rat ileum. Moreover, we observed a variation in transepithelial resistance of individual tissue preparations, inversely related to the cation selectivity of the tissue, suggesting that Na+ permeability of the tight junctions can vary between preparations.

Electrophysiologic mechanisms and electrocardiographic findings in atrioventricular-nodal reentrant tachycardia in a patient with the scimitar syndrome

We describe a case of a 68-year-old man with scimitar syndrome and an atrioventricular-nodal reentrant tachycardia treated with adenosine. The emphasis in this article is on the electrophysiologic mechanism of and electrocardiographic (ECG) findings in this case of atrioventricular-nodal reentrant tachycardia.

In vivo protection against NMDA-induced neurodegeneration by MK-801 and nimodipine: combined therapy and temporal course of protection

Neuroprotection against excitotoxicity by a combined therapy with the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 and the L-type Ca2+ channel blocker nimodipine was examined using an in vivo rat model of NMDA-induced neurodegeneration. Attention was focused on the neuroprotective potential of this combined drug treatment before and after NMDA-exposure. NMDA was unilaterally injected in the magnocellular nucleus basalis (MBN). Neuronal damage was assessed 12 days after the NMDA-injection by measuring the reduction of cholinergic cortical fibres that originate from the MBN neurons. In controls that received no drug treatment, NMDA-exposure damaged MBN neurons such that 66% of the cholinergic terminals were lost in the ipsilateral parietal cortex. Pretreatment with a nimodipine diet (860 ppm) combined with application of MK-801 (5 mg/kg i.p.) before NMDA-exposure reduced fibre loss by 89% thereby providing a near complete neuroprotection. Combined therapy of MK-801 (5 mg/kg i.p.) and nimodipine (15 mg/kg i.p.) 8 min after NMDA-infusion reduced neuronal injury by 82%, while the same combination given 2 h after the excitotoxic treatment still yielded a 66% protection against neurotoxic damage invoked by NMDA. In conclusion, the present data show that a dual blockade of NMDA-channels and voltage-dependent calcium channels (VDCC's) up to 2 h after NMDA-exposure is able to provide a significant protection against NMDA-neurotoxicity.

Serological studies of Corynebacterium kutscheri and coryneform bacteria using an enzyme-linked immunosorbent assay (ELISA)

An enzyme-linked immunosorbent assay (ELISA) to measure Corynebacterium kutscheri antibodies in mice and rats was developed. Seven C. kutscheri isolates showed considerable serological relationship, but Japanese isolates differed from the British isolates. The ELISA appeared specific since C. kutscheri antigen did not react with antisera against 8 heterologous coryneform species. Antibodies to C. kutscheri were to a limited extent absorbed by autologous and homologous antigen, but not at all by the heterologous coryneform species. In naturally infected wild Rattus norvegicus and laboratory NA rats, the ELISA demonstrated high ODs to C. kutscheri.

Measurement of affinity in serum samples of antigen-free, germ-free and conventional mice after hyperimmunization with 2,4-dinitrophenyl keyhole limpet hemocyanin, using surface plasmon resonance

We previously investigated the primary and secondary responses and hyperimmunization to the T cell-dependent antigen 2,4-dinitrophenyl keyhole limpet hemocyanin (DNP-KLH) in antigen-free (AF), germ-free (GF) and conventional (CV) mice. Both the absolute and relative numbers of DNP-specific IgG-secreting cells in the spleen of AF mice were considerably higher compared to GF and CV mice, especially after hyperimmunization. In the present study we measured the total and DNP-specific IgG concentration in the sera of these hyperimmunized mice using a sensitive sandwich enzyme-linked immunosorbent assay. With respect to the total IgG concentration before and after hyperimmunization, the AF mice showed an almost 13-fold increase after boosting with the antigen; the GF mice showed an approximately 8-fold increase. A slight but non-significant increase was observed in the CV mice. The total as well as the DNP-specific IgG levels in the AF-immunized mice were 2-fold and 5-fold higher compared to GF and CV mice, respectively. With the use of Surface Plasmon Resonance instrumentation (BIAcore, Pharmacia, Uppsala, Sweden) we obtained mean binding affinities (KA) of the polyclonal samples of the three groups of hyperimmunized mice. IgA and IgM samples displayed low affinity for DNP-lysine. The AF mice displayed the highest KA value among IgG antibodies, followed by GF mice, while CV mice showed a 3-fold lower KA compared to AF mice. These differences were mainly determined by the dissociation rate constant (kdiss), since no significant changes were observed in the association rate constant (kass). Furthermore, the sera of the CV mice have a lower percentage of high-affinity antibodies compared to GF and AF mice. These results suggest that besides a higher overall binding affinity seen in AF mice, and to a lesser extent in GF mice, the relative contribution of high-affinity IgG is greater in AF mice compared to CV mice.