In silico Mechanics of Stem Cells Intramyocardially Transplanted with a Biomaterial Injectate for Treatment of Myocardial Infarction

PURPOSE

Biomaterial and stem cell delivery are promising approaches to treating myocardial infarction. However, the mechanical and biochemical mechanisms underlying the therapeutic benefits require further clarification. This study aimed to assess the deformation of stem cells injected with the biomaterial into the infarcted heart.

METHODS

A microstructural finite element model of a mid-wall infarcted myocardial region was developed from ex vivo microcomputed tomography data of a rat heart with left ventricular infarct and intramyocardial biomaterial injectate. Nine cells were numerically seeded in the injectate of the microstructural model. The microstructural and a previously developed biventricular finite element model of the same rat heart were used to quantify the deformation of the cells during a cardiac cycle for a biomaterial elastic modulus (Einj) ranging between 4.1 and 405,900 kPa.

RESULTS

The transplanted cells' deformation was largest for Einj = 7.4 kPa, matching that of the cells, and decreased for an increase and decrease in Einj. The cell deformation was more sensitive to Einj changes for softer (Einj ≤ 738 kPa) than stiffer biomaterials.

CONCLUSIONS

Combining the microstructural and biventricular finite element models enables quantifying micromechanics of transplanted cells in the heart. The approach offers a broader scope for in silico investigations of biomaterial and cell therapies for myocardial infarction and other cardiac pathologies.

Decriminalising and legalising medical assistance in dying

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Effect of biomaterial stiffness on cardiac mechanics in a biventricular infarcted rat heart model with microstructural representation of in situ intramyocardial injectate

Intramyocardial delivery of biomaterials is a promising concept for treating myocardial infarction. The delivered biomaterial provides mechanical support and attenuates wall thinning and elevated wall stress in the infarct region. This study aimed at developing a biventricular finite element model of an infarcted rat heart with a microstructural representation of an in situ biomaterial injectate, and a parametric investigation of the effect of the injectate stiffness on the cardiac mechanics. A three-dimensional subject-specific biventricular finite element model of a rat heart with left ventricular infarct and microstructurally dispersed biomaterial delivered 1 week after infarct induction was developed from ex vivo microcomputed tomography data. The volumetric mesh density varied between 303 mm-3 in the myocardium and 3852 mm-3 in the injectate region due to the microstructural intramyocardial dispersion. Parametric simulations were conducted with the injectate's elastic modulus varying from 4.1 to 405,900 kPa, and myocardial and injectate strains were recorded. With increasing injectate stiffness, the end-diastolic median myocardial fibre and cross-fibre strain decreased in magnitude from 3.6% to 1.1% and from -6.0% to -2.9%, respectively. At end-systole, the myocardial fibre and cross-fibre strain decreased in magnitude from -20.4% to -11.8% and from 6.5% to 4.6%, respectively. In the injectate, the maximum and minimum principal strains decreased in magnitude from 5.4% to 0.001% and from -5.4% to -0.001%, respectively, at end-diastole and from 38.5% to 0.06% and from -39.0% to -0.06%, respectively, at end-systole. With the microstructural injectate geometry, the developed subject-specific cardiac finite element model offers potential for extension to cellular injectates and in silico studies of mechanotransduction and therapeutic signalling in the infarcted heart with an infarct animal model extensively used in preclinical research.

Changes in anthropometrical status and body composition in children with cancer during initial chemotherapy

Children with cancer require adequate nutritional support to prevent malnutrition. This study investigated the impact of chemotherapy on anthropometrical status and body composition during the first six months of treatment. Anthropometrical status and body composition were measured at diagnosis, utilizing standardized protocols and validated S10 InBody bio-electrical impedance (BIA) measurements and compared to subsequent consecutive monthly follow-up measurements to plot changes over time during the first six months. Statistical significance was defined as p < 0.05. Forty-three newly diagnosed children (median age 4 years, IQR: 2.0-7.6; male-female ratio 1:0.9; 53% haematological malignancies and 47% solid tumors) were included. Prevalence of malnutrition varied, with under-nutrition 14% (mid-upper arm circumference (MUAC)/body mass index (BMI)), over-nutrition 9.3% (BMI) and stunting 7% at diagnosis. MUAC (14%) identified fewer participants with underlying muscle store depletion than BIA (41.8%). Chemotherapy exposure acutely exacerbated existing nutritional depletion during the first two months after diagnosis for all variables except fat mass (FM), with contrary effects on cancer type. Haematological malignancies had rapid increases in weight, BMI and FM. All patients had an acute loss of skeletal muscle mass. Nutritional improvement experienced by all cancer types during month two to three of treatment resulted in catch-up growth, with a significant increase in weight (chi2=40.43, p < 0.001), height (chi2=53.79, p < 0.001), BMI (chi2=16.32, p < 0.005), fat free mass (chi2=23.69, p < 0.003) and skeletal muscle mass (chi2=24.19, p < 0.001) after six months. Monthly nutritional assessments, including advanced body composition measurements, are essential to provide timely nutritional interventions to overcome the acute decline in nutritional reserves observed during the first two months of chemotherapy exposure.

The Association of Clinical Characteristics and Tumour Markers With Image-Defined Risk Factors in the Management of Neuroblastoma in South Africa

AIMS

Image-defined risk factors (IDRFs) in neuroblastoma predict surgical complications and management outcomes. As there is a lack of data regarding the association of IDRFs with clinical and pathological factors, this study evaluated the prognostic value of IDRFs to predict neuroblastoma survival outcomes.

MATERIALS AND METHODS

This was a retrospective study including 345 patients and reviewed diagnostic imaging for 20 IDRFs, pleural effusions and ascites. The IDRFs were grouped into five 'primary IDRFs' cohorts with vascular encasement, involvement of multiple body compartments, organ infiltration, airway obstruction and intraspinal extension. The association between clinical, histopathological and biological characteristics of neuroblastoma and management was evaluated.

RESULTS

More patients without IDRFs had operations compared with patients with IDRFs, with a trend towards significance (64.4% versus 35.6%, P = 0.082). Patients with multiple compartment tumour involvement (P = 0.003) and organ infiltration (P < 0.001) had a higher risk of surgical complications. The 5-year overall survival of the group with more than one IDRF was 0.0% and those with pleural effusions or ascites 6.7%, associated with the worst outcome (P = 0.005). The total number of IDRFs was not predictive of the metastatic remission rate (P = 0.585) or overall survival (P = 0.142), with no conclusive association found between IDRF groups and clinical or biological markers.

CONCLUSIONS

Patients with more than one IDRF had the shortest survival time, whereas those with pleural effusions and ascites at diagnosis had a poor outcome. Standardised reporting of IDRFs is crucial for predicting prognosis.

The Association between Tumour Markers and Meta-iodobenzylguanidine Scans in South African Children with High-risk Neuroblastoma

AIMS

Diagnostic and post-induction ¹²³I-meta-iodobenzylguanidine (¹²³I-mIBG) scans have prognostic significance in the treatment of neuroblastoma, but data from low- and middle-income countries are limited due to resource constraints. The aim of this study was to determine the association between neuroblastoma-associated tumour markers (lactate dehydrogenase [LDH], ferritin and MYCN amplification) and ¹²³I-mIBG scans (modified Curie scores and metastatic disease patterns) in predicting complete metastatic response rates (mCR) and overall survival.

MATERIALS AND METHODS

Two hundred and ninety patients diagnosed with high-risk neuroblastoma in South Africa between January 2000 and May 2018 and a subanalysis of 78 patients with diagnostic ¹²³I-mIBG scans were included. Data collection included LDH, ferritin and MYCN amplification at diagnosis. Two nuclear physicians independently determined the modified Curie scores and pattern of distribution for each diagnostic and post-induction ¹²³I-mIBG scans with high inter-rater agreement (r = 0.952) and reliability (K = 0.805). The cut-off values for the diagnostic and post-induction modified Curie scores of ≥7.0 (P = 0.026) and 3 (P = 0.009), respectively, were generated. The association between the tumour markers and the modified Curie score of the ¹²³I-mIBG scans was determined using post-induction mCR and 2-year overall survival.

RESULTS

Diagnostic LDH (P < 0.001), ferritin (P < 0.001) and the diagnostic modified Curie scores (P = 0.019) significantly predicted mCR. Only ferritin correlated with diagnostic modified Curie scores (P = 0.003) but had a low correlation coefficient of 0.353. On multivariable analysis, the only significant covariate for 2-year overall survival at diagnosis was LDH <750 U/l (P = 0.024). A post-induction chemotherapy modified Curie score ≤3.0 had a 2-year overall survival of 46.2% compared with 30.8% for a score >3.0 (P = 0.484).

CONCLUSION

LDH, ferritin and the diagnostic ¹²³I-mIBG scans significantly predicted mCR, but only LDH predicted 2-year overall survival. Ferritin and the modified Curie scores correlated with each other. MYCN amplification neither correlated with any aspect of the ¹²³I-mIBG scans nor significantly predicted mCR or 2-year overall survival. LDH and ferritin are therefore appropriate neuroblastoma tumour markers to be used in low- and middle-income countries with limited or no access to mIBG scans and/or MYCN amplification studies.

Neurodevelopmental and behavioural outcomes of HIV-exposed uninfected and HIV-unexposed children at 2-3 years of age in Cape Town, South Africa

Successful vertical HIV transmission prevention programmes (VTP) have resulted in an expanding population of HIV-exposed uninfected (HEU) infants whose growth, health and neurodevelopmental outcomes could have consequences for future resource allocation. We compared neurodevelopmental and behavioural outcomes in a prospective cohort of 2-3 year old HEU and HIV-unexposed uninfected (HU) children.Women living with and without HIV and their infants were enrolled within three days of birth from a low-risk midwife obstetric unit in Cape Town, South Africa during 2012 and 2013, under WHO Option A VTP guidelines. HIV-uninfected children aged 30-42 months were assessed using the Bayley scales of Infant Development-Third edition (BSID) and Strengths and Difficulties questionnaire (SDQ).Thirty-two HEU and 27 HU children (mean birth weight 3048g vs 3096g) were assessed. HEU children performed as well as HU children on BSID cognitive, language and motor domains. Mean scores fell within the low average range. Mothers of HEU children reported fewer conduct problems but stunting was associated with increased total difficulties on the SDQ.HEU and HU children's performance on the BSID was similar. In this low-risk cohort, HIV exposure did not confer additional risk. Stunting was associated with increased behavioural problems irrespective of HIV exposure.

115 CHARACTERIZING NEUTROPHIL PROFILES IN HORSES FOR RHINOCEROS CAPTURE

Conservation of several African species is becoming essential, and efforts to move threatened animals are causing physiological and reproductive problems. To save these species, a more comprehensive knowledge of their biology and response to stressors is required. Capture stress of rhinoceroses has been quantified (Kruger et al. 2011 Reprod. Fertil. Dev. 23, 181–182) by evaluating leucocyte coping capacity (LCC). LCC is the measurement of the fluorescence of circulating active neutrophils, then expressed as optical density (OD)/1000 neutrophils. The LCC then provides a standardized value between species as we used identical conditions and reagents. To quantify the role of LCC in rhinoceros conservation, it is essential to characterize normal LCC profiles of healthy unstressed rhinoceroses. Horse neutrophils are very similar to rhinoceros neutrophils in their biological activity. The objective of the study was to characterize normal LCC profiles in stallions, geldings, nonpregnant mares, pregnant mares, as well as fillies and colts of various ages as a benchmark for adult and juvenile rhinoceroses. The LCC profiles are shown in Figures 1 to 3. For the colts (days, weeks, and months old) there was little difference in their LCC profile over time. For the fillies (days, weeks, and months old) the LCC response for fillies only days old was significantly (P < 0.05) greater when compared to fillies that were weeks and months old. For the adult horses, the stallions had the lowest overall LCC and were very similar to nonpregnant mares. The LCC of pregnant mares was of significantly (P < 0.5) greater magnitude than that of stallions and nonpregnant mares. The LCC response of gelding was significantly (P < 0.5) greater than that of stallions and nonpregnant mares, but significantly (P < 0.5) lower than that of pregnant mares. The stallion and pregnant mare responses mirrored the quantitative responses of breeding rhinoceros bulls and pregnant rhinoceros cows. From the data (Figure 4) we suggest that breeding males (stallions, elephants, and rhinoceros bulls) have the lowest LCC activity curves, as their breeding activities result in higher daily stresses. We hypothesized that the stressed bulls have their neutrophil activity down regulated by circulating corticosteroids. The converse is true for pregnant females (mares and cows), as they may have more vigorous neutrophils and therefore the highest LCC curves. These basic studies support and validate the role of rapid LCC in stress evaluation of wild caught rhinoceroses and horses could be applicable for captured elephant.

Complications, disease profile and histological yield from percutaneous renal biopsy under real-time US guidance: A retrospective analysis

Objective. The objective of the study was to evaluate (i) the technique used at Universitas Hospital in comparison with other international centres also performing renal biopsies, (ii) the disease profile in patients undergoing renal biopsies, (iii) the complications experienced during and/or after the procedure, and (iv) the histological yield of the biopsies (amount of nephrons per biopsy taken) using this technique. Design. A retrospective descriptive analysis of all patients who underwent percutaneous renal biopsy under ultrasound (US) guidance at the Interventional Radiology Unit, Universitas Hospital, Bloemfontein, was undertaken for the period 1 January 2003 - 31 December 2008. Data obtained from the patients’ files and histology reports were statistically analysed. Results. A total of 112 patients qualified for inclusion in the study, all of whom had proof of renal failure and then had percutaneous renal biopsy performed under US guidance. The histology was diagnostic in 111 (99.1%) of the cases, with more than 5 nephrons present in 105 (93.5%) of the cases. Minor complications were found in 29 (25.8%) of the patients, but no major complications were noted. Primary renal disease was found in 67 (59.8%) of patients, and the renal pathology and failure in 45 (40.2%) of the patients were shown histologically to be owing to systemic disease. Conclusion. The technique utilised for performing percutaneous renal biopsy under US guidance at the Interventional Radiology Unit was shown to be safe, with a diagnostic histological yield comparable with international standards. A small majority or patients suffered primary renal disease in comparison with renal failure owing to systemic illness.

158 DEVELOPMENT OF FIELD ASSAY FOR EVALUATION OF WHITE RHINOCEROS NEUTROPHIL FUNCTION AS A STRESS MARKER

Kruger National Park (KNP) is the primary source of translocated white rhinoceroses (Ceratotherium simum) in South Africa. Capture and transport of the rhinoceroses is a highly successful procedure. However, some relocated rhinoceroses present with fertility problems in the 1–2 years post capture. Novel research has shown that one can assess stress using respiratory neutrophil burst levels in several species (Huber et al. 2006 Protoplasma 229, 221–224; Weyts et al. 1998 Dev. Comp. Immunol. 22, 563–572). The hypothesis is that some rhinoceroses respond poorly to stress. The response to stress might be measurable by a neutrophil function (NF) assay, and NF depression might identify adversely stressed animals. The aim was to develop an in-the-bush test for NF and evaluate the changes in neutrophil activity during capture and loading into transportation crates. Neutrophil function was assayed using a portable luminometer (3M Clean-Trace™, 3M, St. Paul, MN, USA) while driving from one capture to the next. For the reaction mixture, 500 μL of PBS was incubated with 10 μL of fresh heparinized blood at 37.6°C. The incubator unit was power by a 230 V convertor in the vehicle. After 5 min of incubation, 100 μL of luminol was added. This sample was read in the luminometer as a blank and then to the sample, 100 μL of 12-O-tetradecanoylphorbol-13-acetate (TPA), also commonly known as phorbol 12-myristate 13-acetate (PMA), a diester of phorbol, was added. The luminescence readings or relative light units (RLU) were read at 2.5 min and then 5 min after PMA addition. All samples were prepared in triplicate. The readings were then taken every 5 min for 65 min. Two samples of blood were evaluated for each rhinoceros: the first sample at capture (anaesthetic induction) and then a second sample after loading of the rhinoceros into the transport crate, 20 to 30 min later. Two response curves were produced for each rhinoceros using the means of the triplicate readings. The curves were then transformed with a trend line and the area under the curve (AUC) was calculated. The 2 AUC for rhinoceros were then compared statistically using Wilcoxon rank regression, with P < 0.05 considered statistically different. Three distinct response curve patters were seen. Sixty-two percent (16/26) of the rhinoceroses had no statistical (P < 0.05) difference between capture and loading samples. In 5 of 26 (19%), the loading AUC was statistically greater than the capture sample, and in 5 of 26 (19%), the capture AUC was statistically greater than the loading sample. In conclusion, NF can be assayed in the field using the blood of wild caught rhinoceroses. The assay is repeatable and can distinguish 3 populations of wild caught rhinoceroses. The hope is that future research will allow us to identify rhinoceroses that have negative stress reactions and to change the capture conditions to make the process less stressful.

Enhancer of zeste homologue 2 ( EZH-2) expression in breast cancer: a novel marker and potential target

e22154

Background: EZH-2 is a protein involved in cell cycle regulation; it belongs to the Polycomb group of proteins and has been suggested to be associated with aggressive breast cancer. In hormone receptor negative (HR-) breast carcinomas, novel therapeutic targets are needed. Few markers have achieved the success of Her-2/neu as targeted therapy making the search for novel treatment strategies imperative. In our study we investigate the expression of EZH2 in a cohort of hormone receptor negative breast carcinomas. Methods: We identified a consecutive cohort of 84 cases of HR- breast carcinoma in 2005–2006, from the Pathology department archives. Tumor grade, size, presence or absence of DCIS, lymph node status and Her2/neu expression were documented. The race of the patients was also noted. Immunohistochemical staining for EZH2 was performed on paraffin embedded sections. Nuclear expression of EZH2 was considered as positive and the percentage of cells staining positive was estimated. Using the Mann-Whitney U test, the expression of EZH2 was correlated with the tumor characteristics listed above. Results: The mean expression of EZH2 in HR- tumors was estimated at 74% with a median of 80% (0–90). Most of these cases (n= 61) were triple negative; 23 cases were HER-2/neu positive by established criteria. Increasing expression of EZH2 was correlated with increase in tumor size (>2 cm) and increased incidence of lymph node metastasis. No correlation was seen with tumor grade, the presence or absence of DCIS and Her2/neu expression. Race did not appear to have an impact on EZH2 expression. Conclusions: Our findings suggest that EZH2 is expressed in the majority of HR - breast cancer and is associated with aggressive breast carcinomas. EZH2 could be an important therapeutic target in this patient population. The study is ongoing to further characterize EZH2‘s role and its association with survival.

No significant financial relationships to disclose.

Cyclooxygenase inhibitors and the exercise-induced stress response

Objective. This study investigated the effects of single dosages of the non-steroidal anti-inflammatory drug (NSAID) naproxen, and of the coxib, rofecoxib, on the exercise-induced stress response. Design. Eight subjects (age 20.9 ± 1.1 years, weight 70.4 ± 3.9 kg, height 170.9 ± 6.7 cm, body surface area 1.82 ± 0.09 m2, body mass index 24.1 ± 1.3 kg.m-2) took part in a double-blind, drug-placebo, cross-over design study. The experimental procedures were performed on 3 occasions on each volunteer, i.e. once on placebo, once on naproxen (single dose of 1 000 mg) and once on rofecoxib (single dose of 50 mg). Results. Mean post-exercise cortisol values were significantly higher than pre-exercise values with the subjects on placebo (p = 0.0365) and rofecoxib (p = 0.0208), but not on naproxen (p = 0.0732). Post-exercise oral temperatures were significantly higher than pre-exercise temperature values on placebo (p = 0.0153) and rofecoxib (p = 0.0424), but not on naproxen (p = 0.5444). Conclusion. The results of this study suggest a role for cyclooxygenase-1 (COX-1) in the exercise-induced cortisol and temperature response to exercise. South African Journal of Sports Medicine Vol. 18 (1) 2006: pp. 4-8

A study of the killer cell immunoglobulin-like receptor gene KIR2DS1 in a Caucasoid Brazilian population with psoriasis vulgaris

Psoriasis is a chronic inflammatory skin disease whose pathogenesis and genetic background remain unclear. Considering that previous studies have suggested an association of psoriasis vulgaris (PV) and killer cell immunoglobulin-like receptors (KIRs), we typed 15 KIR genes and human leukocyte antigen (HLA)-Cw in 79 Brazilian Caucasoid patients with PV and 110 healthy controls by polymerase chain reaction (PCR) using sequence-specific oligonucleotides and sequence-specific primers. We did not observe a relevant increase in the frequency of the activating KIR2DS1 gene in the PV group [KIR2DS1, 46 of 79 cases (58.2%) vs 40 of 110 controls (36.4%)]. However, an association of KIR2DS1 with Cw*0602+ in 26.5% of PV patients was observed, while it was present in only 5.4% of controls. These results suggest that activating KIR2DS1 gene may not confer susceptibility to PV, and an association of KIR2DS1 gene with the HLA-Cw*0602+ was observed in these patients.

Health research ethics review and needs of institutional ethics committees in Tanzania

This study was undertaken to describe the performance of health research ethics review procedures of six research centres in Tanzania. Data collection was done through a self-administered questionnaire and personal interviews. The results showed that there were on average 11 members (range = 8-14) in each Research Ethic Committee. However, female representation in the committees was low (15.2%). The largest proportion of the committee members was biomedical scientists (51.5%). Others included medical doctors (19.7%), social scientists (7.6%), laboratory technologists (10.6%), religious leaders (4.5%), statisticians (3.0%), teachers (1.5%) and lawyers (1.5). Committee members had different capacities to carry out review of research proposals (no capacity = 2%; limited capacity = 15%; moderate capacity = 20%; good capacity = 48%, excellent capacity = 13%). Only half of the respondents had prior ethics review training. Although the majority deemed that ethical guidelines were very important (66%), there were challenges in the use of ethical guidelines which included lack of awareness on the national accreditation mechanisms for ethics committee (59%). Adherence to ethical principles and regulations was influenced by being a scientist (OR = 42.47), being an employee of a professional organization (OR = 15.25), and having an interests in the use of ethical guidelines (OR = 10.85) These findings indicate the need for capacity strengthening (through training and resource support), inclusion of more female representation and other mandatory professions to the research ethics committees.

Reasons for delay in initiation of antiretroviral therapy in a population of HIV-infected South African children

The aim of this study was to determine the reasons for delay of antiretroviral therapy (ART) in eligible HIV-infected children after the implementation of the South African National ART programme in April 2004, and to describe implemented interventions to improve ART access. This descriptive, retrospective audit included all HIV-infected children attending an ART clinic from April to December 2004, summarizing the following: (i) demographic data; (ii) HIV disease stage; (iii) CD4+ counts/percentages; (iv) ART eligibility and (v) reasons for ART delay. There were 276 study participants with a mean age of 4 years 4 months (range: 1 month-13 years). According to the South African national guidelines, 243 children were eligible for ART, but only 96 children were initiated on treatment during the study period, which was 39.5% of the eligible group and 34.8% of the total group. Important reasons for treatment delay were: (i) co-infection with tuberculosis (26.4%); (ii) lack of human resources (20.3%); (iii) socio-economic obstacles (17.3%) and (iv) incorrect disease stage classification (13.7%). Paediatric ART clinics need to co-operate closely with existing tuberculosis clinics for the effective management of tuberculosis co-infection; address socio-economic factors of HIV-affected families, especially the legal guardianship in orphans and improve their own staff capacity and the education of medical staff in HIV/AIDS management.

Prevalence of vaccine-derived polioviruses in stools of immunodeficient children in South Africa

AIMS

The aim of the study was to determine the prevalence of vaccine-derived polioviruses (VDPVs) in stool specimens of immunodeficient patients such as HIV-positive children (including those with an AIDS indicator condition, according to the Centres for Disease Control and Prevention classification) by applying various molecular techniques.

METHODS AND RESULTS

A total of 164 stool samples from HIV-positive children and 23 stool samples from healthy immunocompetent children (the control group) were analysed during 2003 and 2004. By applying a reverse transcription polymerase chain reaction (RT-PCR) in combination with a nested PCR, a total of 54 enteroviruses were detected in the stool specimens of the immunodeficient children. The use of restriction enzymes and a Sabin specific RT-triplex PCR confirmed the presence of 13 polioviruses (PVs), such as seven Sabin PV type 1, four Sabin PV type 3 and two Sabin PV type 2 isolates. The 5'untranslated region and the VP1 capsid-encoding protein of the 13 PVs and the three PVs from the stools of the immunocompetent children were partially sequenced and their genetic relatedness was deduced from the constructed phylogenetic trees. The majority of the PVs isolated from the stools of the immunodeficient children (10 of 13 isolates) were classified as 'oral poliovirus vaccine (OPV)-like viruses', as these isolates had close sequence relationships (>99% in VP1 nucleotide sequences) to the original Sabin PV vaccine strains. Three PVs showed < or =99% VP1 sequence identity to the Sabin PV vaccine strains and were classified as 'suspected' immunodeficient VDPVs (iVDPVs). All of the OPV-like isolates and the 'suspected' iVDPVs carried mutations at specific positions in their partially sequenced regions, which have been associated with reversion of the attenuated Sabin PV vaccine strains to increased neurovirulence.

CONCLUSIONS

Thus, this study adds further evidence to the observation that immunodeficient individuals may excrete OPV strains with potential neurovirulent phenotypes.

SIGNIFICANCE AND IMPACT OF THE STUDY

Prolonged excretion of PVs by immunodeficient individuals is of major concern, because continued replication of PVs in the human gut could result in the reversion of these viruses to greater neurovirulence. When exposed to OPV, immunodeficient patients may become chronically infected, spreading potentially neurovirulent VDPVs for many months or years to close contacts and children who are no longer being vaccinated after termination of OPV vaccination in the near future.

Middle cerebral artery peak systolic velocity: a new Doppler parameter in the assessment of growth-restricted fetuses

OBJECTIVE

The aims of this study were to determine if there is a relationship between middle cerebral artery (MCA) peak systolic velocity (PSV) and perinatal mortality in preterm intrauterine growth-restricted (IUGR) fetuses, to compare the performance of MCA pulsatility index (PI), MCA-PSV and umbilical artery (UA) absent/reversed end-diastolic velocity (ARED) in predicting perinatal mortality, to determine the longitudinal changes that occur in MCA-PI and MCA-PSV in these fetuses, and to test the hypothesis that MCA-PSV can provide additional information on the prognosis of hypoxemic IUGR fetuses.

METHODS

This was a retrospective cross-sectional study of 30 IUGR fetuses (estimated fetal weight < 3(rd) percentile; UA-PI > 95% CI) in which the last MCA-PI, MCA-PSV and UA values were obtained within 8 days before delivery or fetal demise. Among the 30 fetuses, there were 10 in which at least three consecutive measurements were performed before delivery and these were used for a longitudinal study. MCA-PSV and MCA-PI values were plotted against normal reference ranges and were considered abnormal when they were above the MCA-PSV or below the MCA-PI reference ranges.

RESULTS

Gestational age at delivery ranged between 23 + 1 and 32 + 5 (median, 27 + 6) gestational weeks. Birth weight ranged from 282 to 1440 (median, 540) g. There were 11 perinatal deaths. Forward stepwise logistic regression indicated that MCA-PSV was the best parameter in the prediction of perinatal mortality (odds ratio, 14; 95% CI, 1.4-130; P < 0.05) (Nagerlke R(2) = 31). In the 10 fetuses studied longitudinally, an abnormal MCA-PI preceded the appearance of an abnormal MCA-PSV. In these fetuses, the MCA-PSV consistently showed an initial increase in velocity; before demise or the appearance of a non-reassuring test in seven fetuses, there was a decrease in blood velocity. The MCA-PI presented an inconsistent pattern.

CONCLUSIONS

In IUGR fetuses, the trends of the MCA-PI and MCA-PSV provide more clinical information than does one single measurement. A high MCA-PSV predicts perinatal mortality better than does a low MCA-PI. We propose that MCA-PSV might be valuable in the clinical assessment of IUGR fetuses that have abnormal UA Doppler.

Cyclooxygenase inhibitors and the exercise-induced stress response

Objective. This study investigated the effects of single dosages of the non-steroidal anti-inflammatory drug (NSAID) naproxen, and of the coxib, rofecoxib, on the exercise-induced stress response. Design. Eight subjects (age 20.9 ± 1.1 years, weight 70.4 ± 3.9 kg, height 170.9 ± 6.7 cm, body surface area 1.82 ± 0.09 m2, body mass index 24.1 ± 1.3 kg.m-2) took part in a double-blind, drug-placebo, cross-over design study. The experimental procedures were performed on 3 occasions on each volunteer, i.e. once on placebo, once on naproxen (single dose of 1 000 mg) and once on rofecoxib (single dose of 50 mg). Results. Mean post-exercise cortisol values were significantly higher than pre-exercise values with the subjects on placebo (p = 0.0365) and rofecoxib (p = 0.0208), but not on naproxen (p = 0.0732). Post-exercise oral temperatures were significantly higher than pre-exercise temperature values on placebo (p = 0.0153) and rofecoxib (p = 0.0424), but not on naproxen (p = 0.5444). Conclusion. The results of this study suggest a role for cyclooxygenase-1 (COX-1) in the exercise-induced cortisol and temperature response to exercise. South African Journal of Sports Medicine Vol. 18 (1) 2006: pp. 4-8

Poliovirus vaccine strains detected in stool specimens of immunodeficient children in South Africa

After exposure to the oral poliovirus vaccine (OPV), immunocompetent persons excrete poliovirus (PV) vaccine strains for a limited period. In contrast, immunodeficient individuals remain sometimes chronically infected, and in some cases, PV excretion times as long as 10 years have been reported. During prolonged replication in the human intestine, the PV vaccine strain almost invariably reverts its attenuated character and acquires neurovirulent properties (vaccine-derived PVs, or VDPVs), which resemble wild-type PV strains. The aim of this study was to determine the occurrence of OPV strains in stools of immunodeficient children from a selected area in South Africa, as a first step toward future research on the prevalence and potential health impact of VDPVs. In a period of 1 year, a total of 164 stool samples of HIV-positive children aged 4 months to 8 years were studied for the excretion of OPV strains. In addition, 23 stool samples from healthy immunocompetent children were analyzed after receiving their OPV immunization. By applying a reverse transcription-polymerase chain reaction in combination with a nested PCR, a total of 54 enteroviruses (EVs) were detected in the stool specimens of the immunodeficient children. Using restriction enzyme analysis, 13 PVs were distinguished from 41 nonpolio EVs (NPEVs). A Sabin-specific RT-triplex PCR confirmed the presence of 7 Sabin PV type 1, 4 Sabin PV type 3, and 2 Sabin PV type 2 isolates. The majority of the NPEV group was made up of 7 coxsackievirus B3 (CBV3), 6 echovirus 11 (ECV11), 5 ECV9, and 3 coxsackievirus A6 (CAV6) isolates. According to the results, two of the immunodeficient patients (P023 and P140) who had received their last OPV immunization more than 15 months before (vaccinated at 14 weeks of age) tested positive for Sabin PVs types 3 and 1, respectively. A 5-year-old immunodeficient patient (P052) who had received her last OPV immunization more than 42 months before (vaccinated at 18 months of age) tested positive for Sabin PV type 1. These results suggested that immunodeficient patients vaccinated with OPV might excrete potentially pathogenic VDPVs for a prolonged period. These VDPVs may circulate in the community, resulting in possible infections in the unvaccinated population. Therefore, the information obtained in this study would be essential for strategies aimed at the protection of both immunodeficient as well as immunocompetent individuals against complications of vaccination with OPV.

Effects of the mutation R145G in human cardiac troponin I on the kinetics of the contraction-relaxation cycle in isolated cardiac myofibrils

Familial hypertrophic cardiomyopathy (FHC) has been linked to mutations in sarcomeric proteins such as human cardiac troponin I (hcTnI). To elucidate the functional consequences of the mutation hcTnI(R145G) on crossbridge kinetics, force kinetics were analysed in murine cardiac myofibrils carrying either the mutant or the wild-type protein. The mutation was introduced into the myofibrils in two different ways: in the first approach, the endogenous Tn was replaced by incubation of the myofibrils with an excess of reconstituted recombinant hcTn containing either hcTnI(WT) or hcTnI(R145G). Alternatively, myofibrils were isolated either from non-transgenic or transgenic mice expressing the corresponding mcTnI(R146G) mutation. In myofibrils from both models, the mutation leads to a significant upward shift of the passive force-sarcomere length relation determined at pCa 7.5. Addition of 5 mm BDM (2,3-butandione-2-monoxime), an inhibitor of actomyosin ATPase partially reverses this shift, suggesting that the mutation impairs the normal function of cTnI to fully inhibit formation of force-generating crossbridges in the absence of Ca(2)(+). Maximum force development (F(max)) is significantly decreased by the mutation only in myofibrils exchanged with hcTnI(R145G) in vitro. Ca(2)(+) sensitivity of force development was reduced by the mutation in myofibrils from transgenic mice but not in exchanged myofibrils. In both models the rate constant of force development k(ACT) is reduced at maximal [Ca(2)(+)] but not at low [Ca(2)(+)] where it is rather increased. Force relaxation is significantly prolonged due to a reduction of the relaxation rate constant k(REL). We therefore assume that the impairment in the regulatory function of TnI by the mutation leads to modulations in crossbridge kinetics that significantly alter the dynamics of myofibrillar contraction and relaxation.

The effect of neighbouring klipspringer on the scent–marking behaviour of a group of klipspringer in the Kruger National Park

Both the male and the female klipspringer scent-mark their ranges. A pair of pre-orbital glands below the eyes produces the scent. The secretion is a sticky, substance that is deposited on a suitable twig. Klipspringer scent marks were surveyed in a specific klipspringer range in the Kruger National Park with the use of a strip transect method. The results showed that klipspringer in the Kruger National Park scent-mark more frequently on the boundaries of their ranges and also more on those sides where there is another resident klipspringer group.

Expression of ERRP in normal and neoplastic pancreata and its relationship to clinicopathologic parameters in pancreatic adenocarcinoma

INTRODUCTION AND AIMS

Epidermal growth factor (EGF) and its receptor (EGFR) play crucial roles in cellular signaling in many malignancies, including pancreatic neoplasia. Attenuation of EGFR signaling has been considered novel strategy for the management of human malignancies in several ongoing clinical trials. We recently isolated a novel negative regulator of EGFR, termed EGF receptor related protein (ERRP), whose expression appears to attenuate EGFR activation. In the current study, the expression of ERRP in normal and neoplastic pancreas was investigated and correlated with the clinicopathologic parameters in pancreatic ductal adenocarcinoma (DA).

METHODOLOGY

Using rabbit polyclonal antibody that specifically interacts with ERRP, immunohistochemical staining was performed on 45 benign pancreata and 106 cases of DA. The intensity and percentage of cells with cytoplasmic and membranous staining were scored as 0, 1, 2, or 3. A combined score was calculated as intensity x percent/3, and for comparative analysis, the data were arbitrarily divided into three groups: <20, 20-49, and > or =50. The expression of ERRP was correlated with patient age, gender, race, tumor size, stage, grade, and survival.

RESULTS

ERRP was expressed in most benign ductal epithelium and islet cells, but not in normal acinar cells. In pancreatic ductal adenocarcinoma, ERRP expression frequency decreased progressively from well (WD) to moderate (MD) to poorly differentiated (PD) carcinoma (58%, 43%, and 15% respectively, < 0.001). ERRP expression was correlated with survival in DA showing decreased median survival with decreased ERRP score ( = 0.0035). Median survival of the lower intensity (0 or 1) group was less than that of the higher intensity (2 or 3) group (8 14 months, = 0.002). The higher expressing group (> or =50% of cells) had longer median survival (17 months) than the lower expressing (<50% of cells) group (10 months, = 0.003). Stepwise multiple regression analyses revealed that ERRP expression score and tumor grade are the significant predictors of survival in pancreatic ductal carcinomas ( < 0.03).

CONCLUSION

ERRP is usually expressed in benign ductal epithelium, but not in ductal adenocarcinoma. Its expression decreases with decreasing tumor differentiation. Low levels of ERRP are associated with poor clinical outcome, suggesting that progressive loss of ERRP, a negative regulator of EGFR, may partly stimulate aggressive tumor cell growth in pancreatic adenocarcinoma.

Relation of the static compliance curve and positive end-expiratory pressure to oxygenation during one-lung ventilation

BACKGROUND

Positive end-expiratory pressure (PEEP) is commonly applied to the ventilated lung to try to improve oxygenation during one-lung ventilation but is an unreliable therapy and occasionally causes arterial oxygen partial pressure (PaO(2)) to decrease further. The current study examined whether the effects of PEEP on oxygenation depend on the static compliance curve of the lung to which it is applied.

METHODS

Forty-two adults undergoing thoracic surgery were studied during stable, open-chest, one-lung ventilation. Arterial blood gases were measured during two-lung ventilation and one-lung ventilation before, during, and after the application of 5 cm H(2)O PEEP to the ventilated lung. The plateau end-expiratory pressure and static compliance curve of the ventilated lung were measured with and without applied PEEP, and the lower inflection point was determined from the compliance curve.

RESULTS

Mean (+/- SD) PaO(2) values, with a fraction of inspired oxygen of 1.0, were not different during one-lung ventilation before (192 +/- 91 mmHg), during (190 +/- 90), or after ( 205 +/- 79) the addition of 5 cm H(2)O PEEP. The mean plateau end-expiratory pressure increased from 4.2 to 6.8 cm H(2)O with the application of 5 cm H(2)O PEEP and decreased to 4.5 cm H(2)O when 5 cm H(2)O PEEP was removed. Six patients showed a clinically useful (> 20%) increase in PaO(2) with 5 cm H(2)O PEEP, and nine patients had a greater than 20% decrease in PaO(2). The change in PaO(2) with the application of 5 cm H(2)O PEEP correlated in an inverse fashion with the change in the gradient between the end-expiratory pressure and the pressure at the lower inflection point (r = 0.76). The subgroup of patients with a PaO(2) during two-lung ventilation that was less than the mean (365 mmHg) and an end-expiratory pressure during one-lung ventilation without applied PEEP less than the mean were more likely to have an increase in PaO(2) when 5 cm H(2)O PEEP was applied.

CONCLUSIONS

The effects of the application of external 5 cm H(2)O PEEP on oxygenation during one-lung ventilation correspond to individual changes in the relation between the plateau end-expiratory pressure and the inflection point of the static compliance curve. When the application of PEEP causes the end-expiratory pressure to increase from a low level toward the inflection point, oxygenation is likely to improve. Conversely, if the addition of PEEP causes an increased inflation of the ventilated lung that raises the equilibrium end-expiratory pressure beyond the inflection point, oxygenation is likely to deteriorate.

Validation of a modified Early Warning Score in medical admissions

The Early Warning Score (EWS) is a simple physiological scoring system suitable for bedside application. The ability of a modified Early Warning Score (MEWS) to identify medical patients at risk of catastrophic deterioration in a busy clinical area was investigated. In a prospective cohort study, we applied MEWS to patients admitted to the 56-bed acute Medical Admissions Unit (MAU) of a District General Hospital (DGH). Data on 709 medical emergency admissions were collected during March 2000. Main outcome measures were death, intensive care unit (ICU) admission, high dependency unit (HDU) admission, cardiac arrest, survival and hospital discharge at 60 days. Scores of 5 or more were associated with increased risk of death (OR 5.4, 95%CI 2.8-10.7), ICU admission (OR 10.9, 95%CI 2.2-55.6) and HDU admission (OR 3.3, 95%CI 1.2-9.2). MEWS can be applied easily in a DGH medical admission unit, and identifies patients at risk of deterioration who require increased levels of care in the HDU or ICU. A clinical pathway could be created, using nurse practitioners and/or critical care physicians, to respond to high scores and intervene with appropriate changes in clinical management.

Hepatitis B--a major threat to childhood survivors of leukaemia/lymphoma

This prospective descriptive study was undertaken to determine: the proportion of paediatric oncology patients with prior exposure to hepatitis B at cancer diagnosis; the risk and risk factors for acquisition of hepatitis B infection during chemotherapy; and the development of a prevention policy. Sixty African children were included in this study. At the time of cancer diagnosis, 67.7 per cent had not been exposed to hepatitis B, and none had active infection. After follow-up (median of 20 months; range 4-81 months) 23.3 per cent had active hepatitis B infection, which was subclinical in the majority of cases. The diagnosis of leukaemia/lymphoma posed a major risk factor for the acquisition of active hepatitis B infection (chi-square 7.0; p-value = 0.008), probably due to intensive chemotherapy regimens and severity of immunosuppression. No association with gender, age, place of origin, or number of blood transfusions was found. Patients with leukaemia/lymphoma were at an increased risk for horizontal transmission of hepatitis B. A policy of active surveillance for infective carriers of hepatitis B infection and passive immunization of seronegative immunosuppressed patients must be implemented to limit the endemic infection in paediatric oncology units.

Meconium staining and meconium aspiration syndrome. Is there seasonal variation?

OBJECTIVE

To determine whether the incidence of pregnancies complicated by meconium-stained amniotic fluid (MSAF) or meconium aspiration syndrome (MAS) differs with seasonal changes.

METHODS

An established perinatal database was used to identify all term (> or = 37 weeks) singleton gestations resulting in a live birth from January 1, 1997 to December 31, 1999. Patients were divided into groups based on the season of delivery: winter (December-February), spring (March-May), summer (June-August), and fall (September-November). Rates of MSAF (%MSAF/total deliveries) and MAS (%MAS/total deliveries) were calculated and compared among seasons. Local climatic data (average monthly temperature and monthly precipitation) were obtained from the National Weather Service. Multiple logistic regression analysis was performed to control for the effects of confounding variables and odds ratio (OR) with 95% confidence intervals (CI) were calculated. p < 0.05 was considered significant.

RESULTS

Over the 3-year study period there were a total of 14,888 deliveries meeting the criteria. MSAF occurred in 3,206 (21.5%) deliveries and MAS developed in 92 (0.6% of total, 2.9% of MSAF). There were no differences in the rate of MSAF (p = 0.2) or MAS (p = 0.6) between seasons. By logistic regression neither season, temperature, nor precipitation were associated with MSAF or MAS.

CONCLUSIONS

Our findings suggest that over the period examined there were no significant seasonal variations in the incidence of MSAF or MAS.

Effect of palm oil on plasma lipoprotein concentrations and plasma low-density lipoprotein composition in non-human primates

Palm oil (PO) contains approximately 43% of palmitic acid. It is the most abundant saturated fatty acid in the diet and it is generally considered the primary cholesterol (C)-raising fatty acid. However, the effect of palmitic acid on plasma cholesterol appears to depend on the cholesterol content of the diet. The aim of this study was to determine the effect of PO with either a high-fat, high-C or moderate-fat, moderate-C diet on lipoprotein C and low-density lipoprotein (LDL) composition. Fifty adult, male vervet monkeys were randomly assigned to the high-fat diet group (HFD: 35%E fat, approximately 0.106 mg C/kJ; n = 30) and the moderate-fat diet group (MFD: 30%E fat, approximately 0.027 mg C/kJ; n = 30). Baseline LDL-C, high-density lipoprotein (HDL)-C and body weight were used to stratify the vervets into comparable experimental groups within each dietary group. The HFD group was divided into two groups of 10 each: one group continued with the HFD in which 8.1%E was derived from lard (AF); in the other group, AF was substituted isocalorically with PO. The MFD group was divided into three groups of 10 each: one group continued with the MFD in which 11.8%E was derived from AF; in the other two groups, the AF was substituted isocalorically with either sunflower oil (SO) or PO. This article presents preliminary results on plasma lipoproteins and LDL composition after 6 months of dietary intervention. Plasma total and LDL-C was higher in all the groups, but the mean changes elicited by PO with either the HFD or MFD were no different from that observed with AF and SO. There was no difference in the mean change of LDL molecular weight within the HFD and MFD. It is concluded that PO is no different from AF (HFD and MFD) or SO (MFD) in its cholesterolaemic effect.

Posttransplantation: emerging and future therapies

Liver transplantation in patients infected with hepatitis B virus (HBV) commonly results in reinfection that, if untreated, often compromises the viability of the allograft and negatively influences survival. Posttransplant treatment with hepatitis B immune globulin (HBIG) is now the standard of care, but patients appear to require lifelong treatment to prevent reinfection. In the past several years, new management strategies in patients with HBV have been developed, with an aim to decrease HBV-DNA replication before transplantation. Such an approach should increase the success of transplantation by decreasing the risk of reinfection and thus preventing recurrent disease posttransplantation. Nucleoside analogues, either alone or in conjunction with HBIG, are currently in use and are being studied in clinical trials as a means of preventing viral recurrence. Ganciclovir, famciclovir, and lamivudine all have demonstrated efficacy, although they vary in terms of effectiveness. Resistance may develop with the use of these agents and leads to reinfection by the mutant virus. Combination therapy may minimize the risk of viral mutation. Research continues to search for more effective ways to prevent and, if necessary, treat viral recurrence in patients undergoing liver transplantation for HBV.

Identification of Id4 as a regulator of BRCA1 expression by using a ribozyme-library-based inverse genomics approach

Expression of the breast and ovarian cancer susceptibility gene BRCA1 is down-regulated in sporadic breast and ovarian cancer cases. Therefore, the identification of genes involved in the regulation of BRCA1 expression might lead to new insights into the pathogenesis and treatment of these tumors. In the present study, an "inverse genomics" approach based on a randomized ribozyme gene library was applied to identify cellular genes regulating BRCA1 expression. A ribozyme gene library with randomized target recognition sequences was introduced into human ovarian cancer-derived cells stably expressing a selectable marker [enhanced green fluorescence protein (EGFP)] under the control of the BRCA1 promoter. Cells in which BRCA1 expression was upregulated by particular ribozymes were selected through their concomitant increase in EGFP expression. The cellular target gene of one ribozyme was identified to be the dominant negative transcriptional regulator Id4. Modulation of Id4 expression resulted in inversely regulated expression of BRCA1. In addition, increase in Id4 expression was associated with the ability of cells to exhibit anchorage-independent growth, demonstrating the biological relevance of this gene. Our data suggest that Id4 is a crucial gene regulating BRCA1 expression and might therefore be important for the BRCA1 regulatory pathway involved in the pathogenesis of sporadic breast and ovarian cancer.

Giant bronchial carcinoid tumors: a multidisciplinary approach

BACKGROUND

Bronchial carcinoid tumors account for approximately 2% of all lung tumors. Although they were considered benign lesions, they are now categorized malignant, occasionally with poor prognosis. The clinical symptoms can be highly variable and are often present for many years before diagnosis. Whereas some carcinoids are entirely asymptomatic, others are accompanied by carcinoid or paraneoplastic syndromes.

METHODS

We describe the multidisciplinary management of a 34-year-old female patient with a massive actively secreting bronchial carcinoid tumor of the right lung. Furthermore, we provide a review of the literature regarding the operative treatment and the perioperative management of pulmonary carcinoid tumors with respect to surgical, anesthetic, radiologic, and pathologic considerations.

RESULTS

In the reported case, the first symptoms were chronic watery diarrhea, skin flushing, progressive shortness of breath, and increasing right shoulder pain. When the patient initially presented at our institution, the tumor had already reached an enormous size and it involved the right and left atrium as well as the atrial septum. Using an evidence-based, multidisciplinary approach the patient was treated successfully with extended surgical resection.

CONCLUSIONS

Carcinoid tumors are potentially curable even if they reach a significant size and thus an aggressive strategy is warranted. The management of such cases requires careful investigation, planning, and treatment with collaborative expertise provided by a multidisciplinary team. We demonstrated that this approach can lead to a favorable outcome in what first appeared to be a formidable and unresectable tumor.

Selective versus non-selective laser photocoagulation of placental vessels in twin-to-twin transfusion syndrome

OBJECTIVE

We have recently described a surgical technique for the treatment of twin-to-twin transfusion syndrome (TTTS) that allows precise identification of vascular anastomoses (selective laser photocoagulation of communicating vessels, or S-LPCV). The purpose of this study was to compare S-LPCV with the previous non-selective technique (NS-LPCV) that targeted all vessels crossing the dividing membrane.

MATERIALS AND METHODS

Patients with TTTS were treated with NS-LPCV from May 1994 to June 1997 and with S-LPCV from July 1997 to December 1999. TTTS was defined as polyhydramnios of > or = 8 cm maximum vertical pocket (MVP) in the recipient twin and oligohydramnios of < or = 2 cm MVP in the donor twin. Outcome was measured as survival per number of pregnancies and per number of fetuses together with limited morbidity data.

RESULTS

NS-LPCV was used in 18 patients and 74 were treated with S-LPCV. Three patients interrupted their pregnancies electively after surgery (S-LPCV) and were removed from further analysis. Survival of at least one fetus was higher in S-LPCV (83.1%) than in NS-LPCV (61.1%) (P = 0.04), mostly due to a lower rate of dual intra-uterine fetal demise in S-LPCV (5.6%) than in NS-LPCV (22%) (P = 0.05). There were more hydropic fetuses in the NS-LPCV group (27%) than in the S-LPCV group (5.4%), but this difference did not account for the results. There was no difference in the survival per number of fetuses between the two groups.

CONCLUSIONS

S-LPCV represents an important evolution in the surgical treatment of TTTS. The use of this technique by all centers should allow better comparison of fetal survival and morbidity rates. S-LPCV should be the standard technique in trials comparing amniocentesis versus laser for the treatment of severe TTTS.

Identification of eIF2Bgamma and eIF2gamma as cofactors of hepatitis C virus internal ribosome entry site-mediated translation using a functional genomics approach

The 5'-untranslated region of hepatitis C virus (HCV) is highly conserved, folds into a complex secondary structure, and functions as an internal ribosome entry site (IRES) to initiate translation of HCV proteins. We have developed a selection system based on a randomized hairpin ribozyme gene library to identify cellular factors involved in HCV IRES function. A retroviral vector ribozyme library with randomized target recognition sequences was introduced into HeLa cells, stably expressing a bicistronic construct encoding the hygromycin B phosphotransferase gene and the herpes simplex virus thymidine kinase gene (HSV-tk). Translation of the HSV-tk gene was mediated by the HCV IRES. Cells expressing ribozymes that inhibit HCV IRES-mediated translation of HSV-tk were selected via their resistance to both ganciclovir and hygromycin B. Two ribozymes reproducibly conferred the ganciclovir-resistant phenotype and were shown to inhibit IRES-mediated translation of HCV core protein but did not inhibit cap-dependent protein translation or cell growth. The functional targets of these ribozymes were identified as the gamma subunits of human eukaryotic initiation factors 2B (eIF2Bgamma) and 2 (eIF2gamma), respectively. The involvement of eIF2Bgamma and eIF2gamma in HCV IRES-mediated translation was further validated by ribozymes directed against additional sites within the mRNAs of these genes. In addition to leading to the identification of cellular IRES cofactors, ribozymes obtained from this cellular selection system could be directly used to specifically inhibit HCV viral translation, thereby facilitating the development of new antiviral strategies for HCV infection.

The legendary superior strength of the Pfannenstiel incision: a myth?

OBJECTIVE

This study was undertaken to determine whether there is a difference in the frequency of fascial dehiscence between midline vertical lower abdominal and Pfannenstiel incisions among women undergoing obstetric and gynecologic operations.

STUDY DESIGN

A case-control study of 48 cases of fascial dehiscence complicating 17, 995 major operations (8950 cesarean deliveries and 9405 gynecologic procedures) during a 6-year period at Wayne State University Hutzel Hospital, Detroit, was performed. Univariate analysis identified significant independent variables related to fascial dehiscence. Stepwise logistic regression analysis then identified those risk factors that were independently associated with fascial dehiscence.

RESULTS

Among the 48 patients who underwent repair of fascial dehiscence after a major obstetric or gynecologic operation, 27 were from the obstetric service and 21 were from the benign and cancer gynecologic services. Wound dehiscence occurred in 10 vertical incisions and 17 Pfannenstiel incisions among the obstetric patients and in 12 vertical and 9 Pfannenstiel incisions among the gynecologic patients. The risk for dehiscence with vertical lower abdominal incisions was not increased with respect to that associated with Pfannenstiel incisions (P =.39, 2-tailed). This finding was true for all patients (odds ratio, 1.3; 95% confidence interval, 0.7-2.6), obstetric patients (odds ratio, 1.3; 95% confidence interval, 0.5-3.4), and gynecologic patients (odds ratio, 1.5; 95% confidence interval, 0.5-4.0). Forty-seven of the 48 case patients had documented wound infections, compared with 1 of the 144 control subjects (P <.0001, odds ratio, 37.8; 95% confidence interval, 14.8-96.8).

CONCLUSION

Wound infection was the most important risk factor for fascial dehiscence among women who underwent major obstetric and gynecologic operations. Our results do not support the long-held belief that Pfannenstiel incisions are stronger than lower abdominal vertical incisions and reduce the risk for fascial dehiscence.

Prevalence of attention-deficit/hyperactivity disorder and conduct disorder among substance abusers

BACKGROUND

This cross-sectional study sought to determine the prevalence of attention-deficit/hyperactivity disorder (ADHD) and conduct disorder among adults admitted to 2 chemical dependency treatment centers. It was hypothesized that ADHD alone or in combination with conduct disorder would be overrepresented in a population of patients with psychoactive substance use disorders.

METHOD

Two hundred one participants were selected randomly from 2 chemical dependency treatment centers. Standardized clinical interviews were conducted using the Structured Clinical Interview for DSM-IV, the Addiction Severity Index, and DSM-IV criteria for ADHD. Reliabilities for the diagnostic categories were established using the Cohen kappa, and the subgroups of individuals with and without ADHD and conduct disorder were compared.

RESULTS

Forty-eight (24%) of the participants were found to meet DSM-IV criteria for ADHD. The prevalence of ADHD was 28% in men (30/106) and 19% in women (18/95; NS). Seventy-nine participants (39%) met criteria for conduct disorder, and 34 of these individuals also had ADHD. Overall, individuals with ADHD (compared with those without ADHD) were more likely to have had more motor vehicle accidents. Women with ADHD (in comparison with women without ADHD) had a higher number of treatments for alcohol abuse. Individuals with conduct disorder (in comparison with those without conduct disorder) were younger, had a greater number of jobs as adults, and were more likely to repeat a grade in school, have a learning disability, be suspended or expelled from school, have an earlier age at onset of alcohol dependence, and have had a greater number of treatments for drug abuse. They were more likely to have a lifetime history of abuse of and/or dependence on cocaine, stimulants, hallucinogens, and/or cannabis.

CONCLUSION

A significant overrepresentation of ADHD exists among inpatients with psychoactive substance use disorders. Over two thirds of those with ADHD in this sample also met criteria for conduct disorder. Our sample had a very large overlap between ADHD and conduct disorder, and the major comorbidities identified here were attributable largely to the presence of conduct disorder. Individuals who manifest conduct disorder and/or ADHD represent a significant proportion of those seeking treatment for psychoactive substance use disorders. They appear to have greater comorbidity and may benefit from a treatment approach that addresses these comorbidities specifically through medical and behavioral therapies.

Staging of twin-twin transfusion syndrome

OBJECTIVE

The purpose of this study was to evaluate the prognostic value of sonographic and clinical parameters to develop a staging classification of twin-twin transfusion syndrome (TTTS).

STUDY DESIGN

Severe TTTS was defined as the presence of polyhydramnios (maximum vertical pocket of > or = 8 cm) and oligohydramnios (maximum vertical pocket of < or = 2 cm). Nonvisualization of the bladder in the donor twin (-BDT) and absence of presence of hydrops was also noted. The middle cerebral artery, umbilical artery, ductus venosus, and umbilical vein in both fetuses were assessed with pulsed Doppler. Critically abnormal Doppler studies (CADs) were defined as absent/reverse end-diastolic velocity in the umbilical artery, reverse flow in the ductus venosus, or pulsatile flow in the umbilical vein. TTTS was staged as follows: stage I, BDT still visible; stage II, BDT no longer visible, no CADs; stage III, CADs; stage IV, hydrops; stage V, demise of one or both twins. Laser photocoagulation of communicating vessels (LPCV) or umbilical cord ligation was performed depending on the severity of the condition. The study was approved by the Institutional Review Board of St. Joseph's Hospital in Tampa and by the Fetal Therapy Board at Hutzel Hospital, Detroit, and all patients gave informed consent.

RESULTS

A total of 80 of 108 referred patients met criteria for surgery, but only 65 were treated surgically: 48 with LPCV and 17 with umbilical cord ligation. Complete Doppler data were obtainable in 41 of 48 LPCV patients. Survival rates by stage for one or two fetuses were statistically different (chi-squared analysis = 12.9, df = 6, p = 0.044). Neither percent size discordance nor gestational age at diagnosis were predictive of outcome.

CONCLUSION

Staging of TTTS using the proposed criteria has prognostic significance. This staging system may allow comparison of outcome data of TTTS with different treatment modalities.

Dissociation of CH4 at high pressures and temperatures: diamond formation in giant planet interiors?

Experiments using laser-heated diamond anvil cells show that methane (CH4) breaks down to form diamond at pressures between 10 and 50 gigapascals and temperatures of about 2000 to 3000 kelvin. Infrared absorption and Raman spectroscopy, along with x-ray diffraction, indicate the presence of polymeric hydrocarbons in addition to the diamond, which is in agreement with theoretical predictions. Dissociation of CH4 at high pressures and temperatures can influence the energy budgets of planets containing substantial amounts of CH4, water, and ammonia, such as Uranus and Neptune.