Sex differences in mitochondrial gene expression during viral myocarditis

Background

Myocarditis is an inflammation of the heart muscle most often caused by an immune response to viral infections. Sex differences in the immune response during myocarditis have been well described but upstream mechanisms in the heart that might influence sex differences in disease are not completely understood.

Methods

Male and female BALB/c wild type mice received an intraperitoneal injection of heart-passaged coxsackievirus B3 (CVB3) or vehicle control. Bulk-tissue RNA-sequencing was conducted to better understand sex differences in CVB3 myocarditis. We performed enrichment analysis to understand sex differences in the transcriptional landscape of myocarditis and identify candidate transcription factors that might drive sex differences in myocarditis.

Results

The hearts of male and female mice with myocarditis were significantly enriched for pathways related to an innate and adaptive immune response compared to uninfected controls. When comparing females to males with myocarditis, males were enriched for inflammatory pathways and gene changes that suggested worse mitochondrial transcriptional support (e.g., mitochondrial electron transport genes). In contrast, females were enriched for pathways related to mitochondrial respiration and bioenergetics, which were confirmed by higher transcript levels of master regulators of mitochondrial function including peroxisome proliferator-activated receptor gamma coactivator 1 (PGC1α), nuclear respiratory factor 1 (NRF1) and estrogen-related receptor alpha (ERRα). TRANSFAC analysis identified ERRa as a transcription factor that may mediate sex differences in mitochondrial function during myocarditis.

Conclusions

Master regulators of mitochondrial function were elevated in females with myocarditis compared to males and may promote sex differences in mitochondrial respiratory transcript expression during viral myocarditis resulting in less severe myocarditis in females following viral infection.

Sex differences in left-ventricular strain in a murine model of coxsackievirus B3 myocarditis

Myocarditis is typically caused by viral infections, but most cases are thought to be subclinical. Echocardiography is often used for initial assessment of myocarditis patients but is poor at detecting subtle changes in cardiac dysfunction. Cardiac strain, such as global longitudinal strain (GLS) and global circumferential strain (GCS), represents an increasingly used set of measurements which can detect these subtle changes. Using a murine model of coxsackievirus B3 myocarditis, we characterized functional changes in the heart using echocardiography during myocarditis and by sex. We found that 2D GLS, 4D mode, and 4D strains detected a significant reduction in ejection fraction and GLS during myocarditis compared to baseline and in males compared to females. Furthermore, worse GLS correlated to increased levels of CD45+, CD11b+, and CD3+ immune cells. Our findings closely resemble published reports of GLS in patients with myocarditis indicating the usefulness of this animal model for translational studies of myocarditis.

The first Middle East and North Africa expert consensus recommendations for management of advanced gastric cancer

Gastric cancer (GC) ranks as the fifth most prevalent cancer and the fourth deadliest cancer worldwide. In the Middle East and North Africa (MENA) region, GC represents about 4.8% of cancer cases with more than 35,000 new cases in 2020. To strengthen and improve the management of this cancer in the region, a group of MENA experts in the field of GC developed the first MENA consensus recommendations for the management of advanced GC. A total of 28 statements were drafted, discussed and voted on, using a modified Delphi process, during a virtual consensus meeting. The statements addressed the areas of epidemiology, biomarkers and treatment.

The first Middle East and North Africa expert consensus recommendations for the management of advanced colorectal cancer

Colorectal cancer (CRC) is ranked as the third most prevalent and the second deadliest cancer worldwide. In the Middle East and North Africa (MENA) region, the number of CRC cases increased over the past decades and will nearly double by 2030. The lack of clear MENA guidelines for the management of patients with CRC represents a step backwards in the fight against this burden. Therefore a panel of 24 MENA experts in the field of gastrointestinal oncology developed, using a Delphi process, the first consensus recommendations for the management of patients with advanced CRC. Forty-seven different statements were formulated in the areas of epidemiology, screening, biomarkers and treatment. These recommendations will guide, standardize and unify the management of this cancer in the MENA region.

Prevalence and Risk Factors of Burnout Among Female Oncologists From the Middle East and North Africa

Background

Burnout (BO) is a recognized challenge among the oncology workforce. It affects both genders with a higher frequency among women. This study examined the factors contributing to the development of burnout among female oncologists from the Middle East and North Africa (MENA).

Methods

An online cross-sectional survey was distributed to oncology professionals from different countries in the MENA region. The validated Maslach Burnout Inventory (MBI) of emotional exhaustion (EE), Depersonalization (DE), and Personal Achievement (PA) plus questions about demography/work-related factors and attitudes toward oncology were included. Data were analyzed to measure BO prevalence and related factors.

Results

Between 10 February and 15 March 2020, 545 responses were submitted by female oncologists. The responses pre-dated the COVID-19 pandemic emergence in the region. BO prevalence was 71% among female professionals. Women aged <44 years represented 85% of the cohort. Sixty-two percent were married, 52% with children and one-third practiced a hobby. Two-thirds worked in medical oncology, worked for <10 years and 35% worked in academia. The majority (73%) spent >25% on administrative work daily. Nearly half of the respondents (49%) expressed a recurring thought of quitting oncology and 70% had no burnout support or education. Inability to deliver optimal care was reported as distressing for career development in 82%. Factors significantly influencing the BO risk were identified. Marital status, having children, academia and years in practice did not impact the risk of BO among female oncologists from MENA.

Conclusion

Female oncologists from the Middle East and North Africa (MENA) were found to have a high prevalence of BO. In this cohort, the majority of women oncology workers were young and in their early to mid-career stages. Burnout was linked to being younger, practicing in North African nations, having a heavy administrative load, and having persistent thoughts of quitting. Practicing a hobby and engaging in oncology communication, on the other hand, reduced the chance of BO. Burnout support and education, specifically for oncology women, is required.

Dipalmitoylphosphatidylcholine in the heart of mice with lupus might support the hypothesis of dual causes of autoimmune diseases

Lung surfactant dipalmitoylphosphatidylcholine (DPPC) settles on the luminal aspect of blood vessels and forms an active hydrophobic spot - AHS, at which nanobubbles are formed. We hypothesized that large molecules circulating in the blood will adhere and deformed at the gas phase/plasma interface being recognized as autoantigen. NZB mice are afflicted spontaneously with lupus. If their blood vessels contain high levels of DPPC it may support the theory of dual causes of autoimmunity. Phospholipids were extracted from hearts of 8 LPR (lupus) mice and 5 MJP (control mice), and were tested for presence of DPPC. DPPC mg/g was 0.059 in lupus mice and 0.017 in control mice where for equal variance; P = 0.08 and for unequal variance P = 0.048. This trend of 3.5-fold DPPC in lupus mice, supports our hypothesis of dual causes as the origin of autoimmune diseases. The high potential of the hypothesis should be a drive to further explore its validity.

Trpc6 Promotes Doxorubicin-Induced Cardiomyopathy in Male Mice With Pleiotropic Differences Between Males and Females

Background: Doxorubicin is a widely used and effective chemotherapy, but the major limiting side effect is cardiomyopathy which in some patients leads to congestive heart failure. Genetic variants in TRPC6 have been associated with the development of doxorubicin-induced cardiotoxicity, suggesting that TRPC6 may be a therapeutic target for cardioprotection in cancer patients. Methods: Assessment of Trpc6 deficiency to prevent doxorubicin-induced cardiac damage and function was conducted in male and female B6.129 and Trpc6 knock-out mice. Mice were treated with doxorubicin intraperitoneally every other day for a total of 6 injections (4 mg/kg/dose, cumulative dose 24 mg/kg). Cardiac damage was measured in heart sections by quantification of vacuolation and fibrosis, and in heart tissue by gene expression of Tnni3 and Myh7. Cardiac function was determined by echocardiography. Results: When treated with doxorubicin, male Trpc6-deficient mice showed improvement in markers of cardiac damage with significantly reduced vacuolation, fibrosis and Myh7 expression and increased Tnni3 expression in the heart compared to wild-type controls. Similarly, male Trpc6-deficient mice treated with doxorubicin had improved LVEF, fractional shortening, cardiac output and stroke volume. Female mice were less susceptible to doxorubicin-induced cardiac damage and functional changes than males, but Trpc6-deficient females had improved vacuolation with doxorubicin treatment. Sex differences were observed in wild-type and Trpc6-deficient mice in body-weight and expression of Trpc1, Trpc3 and Rcan1 in response to doxorubicin. Conclusions: Trpc6 promotes cardiac damage following treatment with doxorubicin resulting in cardiomyopathy in male mice. Female mice are less susceptible to cardiotoxicity with more robust ability to modulate other Trpc channels and Rcan1 expression.

National approaches to managing cancer care: responses of countries in the MENA region to the COVID-19 pandemic

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic presents serious challenges to cancer care because of the associated risks from the infection itself and the disruption of care delivery. Therefore, many professional societies have published recommendations to help manage patients with cancer during the current pandemic. The objective of our study is to assess the national responses of Middle East North Africa (MENA) countries in terms of publishing relevant guidelines and analyse various components of these guidelines.

METHODS

A survey based on the preliminary review of the literature regarding cancer care adaptations has been developed and then completed by a group of oncologists from the following Arab countries affected by the pandemic: Algeria, Egypt, Iraq, Jordan, Kuwait, Lebanon, Morocco, Oman, Saudi Arabia, Syria, Tunisia, United Arab Emirates and Yemen. The survey inquired about COVID-19 cases, national recommendations regarding general measures of COVID-19 prevention and patient care in oncology as well as their implementation about cancer care adaptations during the pandemic.

RESULTS

Analysis of the COVID-19 pandemic-related guidelines revealed at least 30 specific recommendations that we categorised into seven essential components. All included countries had national guidelines except one country. Estimated full compliances with all specific category recommendations ranged from 30% to 69% and partial compliance ranged from 23% to 61%.

CONCLUSION

There is a very good response and preparedness in the Arab Middle East and North Africa region surveyed. However, there are inconsistencies in the various components of the guidelines across the region, which reflects the evolving status of the pandemic in each country as well as the lack of clear evidence-based guidelines for many of the issues in question. There is a need for a clear framework on essential components that should be included in these guidelines to assure providing the best guidance to the oncology community.

Burnout in oncology: Magnitude, risk factors and screening among professionals from Middle East and North Africa (BOMENA study)

BACKGROUND

Burnout (BO) among oncology professionals (OP) is increasingly being recognized. Early recognition and intervention can positively affect the quality of care and patient safety. This study investigated the prevalence, work and lifestyle factors affecting BO among OPs in the Middle East and North Africa (MENA).

METHODS

An online survey was conducted among MENA OPs between 10 February and 15 March 2020, using the validated Maslach Burnout Inventory of emotional exhaustion (EE), depersonalization (DP) and personal accomplishment (PA), including questions regarding demography/work-related factors and attitudes towards oncology. Data were analysed to measure BO prevalence and risk factors and explore a screening question for BO.

RESULTS

Of 1054 respondents, 1017 participants (64% medical oncologists, 77% aged less than 45 years, 55% female, 74% married, 67% with children and 40% practiced a hobby) were eligible. The BO prevalence was 68% with high levels of EE and DP (35% and 57% of participants, respectively) and low PA scores (49%). BO was significantly associated with age less than 44 years, administrative work greater than 25% per day and the thought of quitting oncology (TQ). Practising a hobby, enjoying oncology communication and appreciating oncology work-life balance were associated with a reduced BO score and prevalence. North African countries reported the highest BO prevalence. Lack of BO education/support was identified among 72% of participants and TQ-predicted burnout in 77%.

CONCLUSIONS

This is the largest BO study in MENA. The BO prevalence was high and several modifiable risk factors were identified, requiring urgent action. TQ is a simple and reliable screening tool for BO.

History and Current State of Radiation Oncology Services and Practice in Jordan

Radiation therapy (RT) for patients with cancer in Jordan began with a small individual effort and has now grown to be one of the most prominent treatment centers in the Middle East. Currently, there are 4 different centers that provide RT not only for the people of Jordan but also for citizens of other neighboring Arab countries. Because Jordan is a developing country, it still faces problems with the insufficient number of RT machines available and their supporting staff (physicists and technologists among others). In this article, we shed light on the history and current status of radiation oncology in Jordan and discuss the challenges we face.

Screening for gastric cancer using exhaled breath samples

BACKGROUND

The aim was to derive a breath-based classifier for gastric cancer using a nanomaterial-based sensor array, and to validate it in a large screening population.

METHODS

A new training algorithm for the diagnosis of gastric cancer was derived from previous breath samples from patients with gastric cancer and healthy controls in a clinical setting, and validated in a blinded manner in a screening population.

RESULTS

The training algorithm was derived using breath samples from 99 patients with gastric cancer and 342 healthy controls, and validated in a population of 726 people. The calculated training set algorithm had 82 per cent sensitivity, 78 per cent specificity and 79 per cent accuracy. The algorithm correctly classified all three patients with gastric cancer and 570 of the 723 cancer-free controls in the screening population, yielding 100 per cent sensitivity, 79 per cent specificity and 79 per cent accuracy. Further analyses of lifestyle and confounding factors were not associated with the classifier.

CONCLUSION

This first validation of a nanomaterial sensor array-based algorithm for gastric cancer detection from breath samples in a large screening population supports the potential of this technology for the early detection of gastric cancer.

Female oncologists in the Middle East and North Africa: progress towards gender equality

Background

Female doctors are increasingly choosing oncology as a career while they are still under-represented in leadership positions globally. The European Society of Medical Oncology has recently surveyed its members regarding gender equality in the work place. Limited data are available from the Middle East. The aim of our study was to survey female oncologists practicing in the Middle East to identify common challenges and suggest areas for improvement.

Methods

A cross-sectional survey was distributed among female participants attending the annual Lebanese Society of Medical Oncology meeting in March 2018, and in the Pan-Arab annual meeting in April 2018. The questionnaire used included questions assessing sociodemographic characteristics, involvement in leadership and academic positions and the impact of career on family life.

Results

Overall, 88 questionnaires were collected from women practicing all over the Middle East. 59% reported that a male doctor was responsible for the work team; however, 57% covered a managerial or leadership role within their job. 64% of the female oncologists believed that their gender had at least moderate, significant and even major impact on their career. Participants reported that their careers have a considerable impact on their relationship with friends and social networking (49%) and their family and marriage (44%). 58% report having problems with finding balance between work and family, and 50% find barriers to attend international meetings. Several ways to improve were suggested, 56% voted for offering development and leadership training specifically women, 45% suggested implementing a flexible work schedule.

Conclusion

In what is considered a male dominant environment, gender equality according to female oncologists working in the Middle East, is very comparable to the world data provided. Several strategies have been identified to continue progress in this domain with the aim to improve academic leadership opportunities and work-life balance for all.

Reduced glutathione increases quercetin stimulatory effects on HDL- or apoA1-mediated cholesterol efflux from J774A.1 macrophages

In our in vitro study, we analyzed the effects of incubation of J774A.1 macrophages with reduced glutathione (GSH) and quercetin on the extent of cellular cholesterol efflux by high-density lipoprotein (HDL) or apolipoprotein A1 (apoA1). This combination was the most potent one among other exogenous and endogenous antioxidant combinations, since it significantly increased the extent of HDL-mediated cholesterol efflux from macrophages by 47% versus control cells, whereas quercetin (20 μM) or GSH (200 μM) alone increased it by only 37% or 17%, respectively. Similarly, apoA1-mediated cholesterol efflux was increased by 11% or 22% in quercetin or quercetin + GSH-treated cells, respectively, versus control cells. These stimulatory effects were noted only after 20 h of cell incubation. The combination of quercetin + GSH demonstrated high scavenging capacity of free radicals versus quercetin or GSH alone. In addition, quercetin + GSH significantly decreased macrophage oxidative stress as measured by the scavenging capacity of free radicals in the cells, the formation of reactive oxygen species, and the levels of cellular glutathione and lipid peroxides. There was no significant effect of quercetin + GSH on cellular HDL binding, on ATP-binding cassette A1 (ABCA1) activity, or on ABCG1 messenger RNA (mRNA) levels. In contrast, mRNA levels for ABCA1 and peroxisome proliferator-activated receptor alpha (PPARα) were both significantly increased by 89% and 93%, respectively, in quercetin + GSH-treated cells versus control cells. Quercetin alone increased the mRNA levels for ABCA1 or PPARα by 42% or 77%, respectively, whereas GSH alone increased it by 22% or 28%, respectively. Mass spectra analysis revealed that oxidized quercetin reacts with GSH to form a new adduct product. We thus conclude that the stimulatory effects of quercetin + GSH on apoA1- or HDL-mediated macrophage cholesterol efflux are related to the ability of GSH to preserve quercetin in its reduced form.

Neural HO-1/sterol interactions in vivo: implications for Alzheimer's disease

BACKGROUND

Up-regulation of heme oxygenase-1 (HO-1) and altered cholesterol (CH) metabolism are characteristic of Alzheimer-diseased (AD) neural tissues. We previously provided evidence of significant HO-1/sterol interactions in vitro (cultured rat astroglia) and in post-mortem human AD brain (Religious Orders Study).

METHODS

The current experiments were designed to further delineate these interactions in vivo by comparing the behavior of HO-1/sterol interactions in two mouse models; (1) a novel HO-1 transgenic mouse (GFAP.HMOX1) engineered to selectively express human HO-1 in the astrocytic compartment and (2) the previously described triple transgenic AD mouse (3xTg-AD). In samples of frontal cortex, total CH, CH precursors and relevant oxysterols were quantified by gas chromatography-mass spectrometry (GC-MS) and HO-1 protein expression was assessed by ELISA. The relationships of HO-1 expression to total CH, CH precursors and total oxysterols were determined for both mouse models using linear regression analysis.

RESULTS

HO-1 expression is increased in GFAP.HMOX1 mice relative to wild type and in 11-12-month-old 3xTg-AD mice (with AD-like phenotype) relative to control mice and 5-6-month-old 3xTg-AD mice (no AD-like phenotype). Total oxysterols significantly decreased as HO-1 expression increased in GFAP.HMOX1 mice expressing high levels of HO-1, whereas total oxysterols increased as HO-1 expression increased in aged 3xTg-AD mice. Total CH and total CH precursors increased as HO-1 protein expression increased in 11-12-month-old 3xTg-AD mice relative to 5-6-month old 3xTg-AD mice.

CONCLUSIONS

Our findings indicate a differential impact of HO-1 on patterns of brain sterol and redox homeostasis that is contingent on the presence or absence of AD-like neuropathology. These data provide fresh insight concerning the regulation of sterol homeostasis within the aging and degenerating CNS which may inform the development of novel therapeutic and preventive strategies for the management of AD and related conditions.

Modification and implementation of NCCN guidelines on lymphomas in the Middle East and North Africa region

In the Middle East and North Africa (MENA) region, cancer has many epidemiologic and clinical features that are different from those in the rest of the world. Additionally, the region has a relatively young population and large disparities in the availability of resources at diagnostic and treatment levels. A critical need exists for regional guidelines on cancer care, including those for lymphoid malignancies. A panel of lymphoma experts from MENA reviewed the 2009 version of the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) on Non-Hodgkin's Lymphoma and Hodgkin Lymphoma and suggested modifications for the region that were discussed with the United States NCCN Lymphoma Panels. This article presents the consensus recommendations.

Alterations in striatal oxidative stress level produced by pharmacological manipulation of dopamine as shown by a novel synthetic marker molecule

Oxidative stress (OS) is thought to participate in neurodegenerative diseases such as Parkinson's disease, but the contribution of dopamine metabolism and auto-oxidation to OS in Parkinson's and other diseases is not clear. Oxidative stress in rat striatum was measured by microdialysis using a novel synthetic compound composed of tyrosine and linoleic acid (LT), and determination of the oxidation products LT-OOH and LT-epoxy by HPLC-MS. Since LT is non-diffusible through the microdialysis membrane, the oxidized products formed in microdialyzate reflect oxidation state in the extracellular compartment. The extracellular oxidative stress (OS(ec)) was compared with intracellular oxidative stress (OS(ic)) as measured by tissue levels of oxidized and reduced glutathione and 7-ketocholesterol. Reserpinization caused an increase in OS(ic) but a reduction in OS(ec). Inhibition of both subtypes of monoamine oxidase (MAO-A and MAO-B) with tranylcypromine caused a reduction in both OS(ic) and OS(ec) whereas selective inhibition of MAO-A with clorgyline caused a reduction in Os(ic) but no change in OS(ec). A high dose (10 mg/kg) of amphetamine caused an increase in OS(ec) whereas a smaller dose (4 mg/kg) caused a reduction in OS(ec). Both doses of amphetamine reduced OS(ic). The present findings are consistent with a role of monoamine oxidase as well as dopamine auto-oxidation in production of striatal OS.

Cancer incidence in Jordan, 1996-2005

Cancer causes 14% of all deaths in Jordan. This paper presents the incidence of cancer in Jordan from 1996 to 2005. Over the 10-year period there were 33 661 cases of cancer. The average crude incidence rate was 66.2 per 100 000 for males and 70.0 per 100 000 for females (age-standardized rates: 119 per 100 000 adult males and 116 per 100 000 adult females). The 5 most frequently reported cancers among adult males were: lung (10.6%), colorectal (9.8%), leukaemia (9.3%), urinary and bladder (8.6%) and prostate (7.4%). For adult females these were: breast (32.0%), colorectal (9.0%), leukaemia (6.7%), thyroid (4.9%) and corpus uteri (4.6%). Cancer rates have changed little since 1996.

A novel compound JPM8: in vivo penile activity promotion in rats, effect on the relaxation and cGMP/cAMP accumulation in isolated rabbit corpora cavernosa

JPM8 is a novel sildenafil-like PDE5 inhibitor. Its efficacy was tested in vivo by the oral administration of drugs to a rat model and recording penile activity changes. Effect on the relaxation of the rabbit cavernosa was tested in vitro using an organ bath were drugs are added to the tissue media and relaxation was recorded using a transducer connected to a chart recorder. The accumulation of cGMP and cAMP was measured by incubation of cavernosa strips and then extracting the produced cGMP and cAMP in the incubation mixture, then quantitating it using ELISA. JPM8 showed increased and promoted sexual and penile activity in rats in a similar but slightly higher trend than the positive control sildenafil. JPM8 was more efficient in relaxing the rabbit corpora cavernosa than sildenafil. The cGMP and cAMP accumulation showed a similar trend for both drugs. We concluded that JPM8 was very effective in promoting sexual activity in rats, relaxing the corpora cavernosa and promoting cGMP accumulation in rabbits.

Effects of Crystal Packing on Photoinduced Proton-Transfer Processes of 2,4-Dinitrobenzylpyridine Derivatives

Photoinduced and thermally activated proton-transfer processes taking place in crystals of 2-(2,4-dinitrobenzyl)pyridine and some of its derivatives are highly sensitive to molecular packing. Small differences in the way the molecules are packed in the crystal are found to dominate molecular properties in controlling the photoactivity of the different phototautomers, leading, for example, to photoactive or photoinert systems. Three compounds, 2-(2,4-dinitrobenzyl)-4-methylpyridine, 1-(2,4-dinitrophenyl)-l-(2-pyridine)ethane and 4′-(2,4-dinitrobenzyl)-4-methyl-2,2′-bipyridine, having different photochemical properties, were prepared and their crystal structures characterized by means of X-ray analysis. In the photoinert crystals the 2,4-dinitrophenyl group is π-stacked with other aromatic rings of neighboring molecules. This arrangement may open some deactivation channels to the excited state which are faster than the proton-transfer process, leading to photoinert crystals. The absence of π-stacking between the chromophore and other aromatic rings leads to photoactive systems. An O atom of the o-nitro group is the only basic atom that is systematically found to interact with the abstracted proton. It seems that this atom is responsible for the photoinduced proton abstraction of the benzylic H atom, while the role of the N atom of the pyridine ring in the proton-abstraction process is mainly inductive.

Effects of propofol and thiopentone on picrotoxin convulsive threshold in the rabbit

The purpose of the present study was to examine the effect of intravenous administration of propofol and thiopentone on picrotoxin-induced seizures using the picrotoxin convulsive threshold test in the rabbit. Neither propofol nor thiopentone at a dose of 1.25 mg/kg had any significant effect on picrotoxin seizure threshold. However, at higher doses (2.5, 5, 10 mg/kg) both propofol and thiopentone produced a significant and dose-dependent increase in the picrotoxin convulsive threshold. These findings suggest that propofol is an effective anticonvulsant against picrotoxin-induced seizures in the rabbit.

Coagulase-negative staphylococci in multiple blood cultures: strain relatedness and determinants of same-strain bacteremia

The frequency of strain relatedness was determined among randomly selected patients with coagulase-negative staphylococcal infections as determined in multiple blood cultures by plasmid typing, determination of species, and antibiotyping. Strain relatedness was demonstrated in 21 of 47 episodes of bacteremia (44.7%) among 34 patients, with a similar percentage among patients with two or one positive blood culture in 24 h (14 of 30 [46.7%] versus 7 of 17 [41.2%], respectively). Same-strain bacteremia was more frequent in cases of infection among patients with a corresponding fever (15 of 21 [71.4%]), among patients infected with organisms from an identifiable source (7 of 9 [77.8%]) and with non-Staphylococcus epidermidis species (9 of 11 [81.8%]), and among patients with nosocomially acquired infections (18 of 36 [50%]). Comparing episodes with or without strain relatedness, no difference was noted in the time to growth (2.1 +/- 1.4 versus 1.9 +/- 0.9 days, respectively), in bacterial growth in two culture bottles (5 of 14 [35.7%] versus 8 of 24 [33.3%], respectively), and in the presence of additional negative blood cultures (9 of 21 [42.9%] versus 11 of 26 [42.3%], respectively). The antibiotypes of all related strains and 7 of 44 (15.9%) unrelated pairs were identical. These findings demonstrate that coagulase-negative staphylococci from multiple blood cultures are frequently unrelated, suggesting a high prevalence of contamination. In the absence of precise measures for demonstrating strain relatedness, the combination of a clinical assessment with antibiotype determination appears to be a suitable alternative.

Thyroid function in children with beta-thalassemia major in north Jordan

Basal thyroid function was assessed by serum thyroxine, tri-iodothyronine and thyroid-stimulating hormone levels in 90 patients 2-10 years old with beta-thalassaemia major. Based on measured serum ferritin levels, patients were classified into two groups: group (I) which included 63 patients with ferritin concentrations ranging from 300 to 7000 ng/ml (mild iron overload) and group (II) which included 27 patients with ferritin concentrations higher than 7000 ng/ml (severe iron overload). The results of thyroid function in both groups were compared with those of 50 control subjects. In group (I), the mean concentrations of all measured hormones were not significantly different from those of the controls. In group (II), the mean concentrations of thyroxine and tri-iodothyronine decreased by 29 and 35 per cent (P < 0.05), respectively, and the mean concentration of thyroid-stimulating hormone showed a 2.6-fold increase (P < 0.01) in comparison with those of the controls. The data clearly demonstrate the occurrence of impaired thyroid function and its possible association with iron overload in a considerable proportion of transfusion-dependent beta-thalassaemic patients.

Effects of glyburide on ischemia-induced changes in extracellular potassium and local myocardial activation: a potential new approach to the management of ischemia-induced malignant ventricular arrhythmias

The increase in extracellular potassium [K+]o levels during the early phase of myocardial ischemia may result in part from activation of adenosine triphosphate-sensitive K+ channels. Glyburide, a second-generation hypoglycemic sulfonylurea, is a potent blocker of these channels. We studied the effects of glyburide on [K+]o and on intramyocardial conduction delay during a 10-minute occlusion of the left anterior descending artery in the dog. K(+)-sensitive electrodes and bipolar plunge electrodes were introduced to record, respectively, [K+]o and local electrograms from close sites in midmyocardial regions in normal, border, and ischemic zones. Recordings were obtained before (control ischemia [CI]) and 20 minutes after intravenous administration of 0.15 mg/kg of glyburide (glyburide plus ischemia [G + I]). During G + I the extent of the increase in [K+]o was less compared to that during CI, and the difference was statistically significant during the first 7 minutes of ischemia in the ischemic zone and during the first 4 minutes of ischemia in the border zone. On the other hand, the degree of local intramyocardial conduction delay was significantly reduced during G + I compared to CI during the entire 10 minutes of ischemia in both the ischemic and border zones. In summary, our results have shown that glyburide significantly reduced the rise of [K+]o and intramyocardial delay during the early phase of acute ischemia and could thus attenuate the electrophysiologic consequences of ischemia that underlie the initial phase of malignant tachyarrhythmias. Although the effects of glyburide may result in part from a direct action of the drug on cardiac adenosine triphosphate-sensitive K+ channels, other metabolic antiischemic effects cannot be ruled out.

Determination of polycyclic aromatic hydrocarbons in environmental samples by high performance thin-layer chromatography and fluorescence scanning densitometry

High performance thin-layer chromatography (HPTLC) with fluorescence scanning densitometry was used for the quantitative determination of polycyclic aromatic hydrocarbons in the soluble organic fraction of air particulate samples. A method using normalized emission response ratios was developed to determine sample identity and to test for peak homogeneity. To preserve the high sample throughput of HPTLC, the two-point calibration method was used for quantitation. The principal advantages of HPTLC as a screening technique for environmental samples are its low cost, methodological simplicity, high sample throughput, and the ability to analyze crude samples with a minimum amount of sample cleanup.

Comparison of methods for separating polycyclic aromatic hydrocarbons by high-performance thin-layer chromatography

A comparison is made of different stationary phases (silica gel, cellulose, acetylated cellulose, and 3-aminopropyl-, ethyl-, octyl-, octadecyl-, and diphenylsilanized silica gel), mobile phases, and development techniques (conventional, continuous, and multiple) for the separation of environmentally important polycyclic aromatic hydrocarbons by high-performance thin-layer chromatography. Reversed-phase separations using octadecylsilanized silica gel and methanol-water or methanol-water-based ternary solvent systems were found to give the best separations. A new development technique, multiple development with application of the mobile phase further up the plate at each successive development, provided superior resolution of the polycyclic aromatic hydrocarbons compared with conventional multiple development.