Turning brain MRI into diagnostic PET: 15O-water PET CBF synthesis from multi-contrast MRI via attention-based encoder-decoder networks

Accurate quantification of cerebral blood flow (CBF) is essential for the diagnosis and assessment of a wide range of neurological diseases. Positron emission tomography (PET) with radiolabeled water (15O-water) is the gold-standard for the measurement of CBF in humans, however, it is not widely available due to its prohibitive costs and the use of short-lived radiopharmaceutical tracers that require onsite cyclotron production. Magnetic resonance imaging (MRI), in contrast, is more accessible and does not involve ionizing radiation. This study presents a convolutional encoder-decoder network with attention mechanisms to predict the gold-standard 15O-water PET CBF from multi-contrast MRI scans, thus eliminating the need for radioactive tracers. The model was trained and validated using 5-fold cross-validation in a group of 126 subjects consisting of healthy controls and cerebrovascular disease patients, all of whom underwent simultaneous 15O-water PET/MRI. The results demonstrate that the model can successfully synthesize high-quality PET CBF measurements (with an average SSIM of 0.924 and PSNR of 38.8 dB) and is more accurate compared to concurrent and previous PET synthesis methods. We also demonstrate the clinical significance of the proposed algorithm by evaluating the agreement for identifying the vascular territories with impaired CBF. Such methods may enable more widespread and accurate CBF evaluation in larger cohorts who cannot undergo PET imaging due to radiation concerns, lack of access, or logistic challenges.

Cost-effectiveness analysis of Manuka honey-Omega-3 combination treatments in treating oxidative stress of pediatric β-thalassemia major

OBJECTIVE

Oxidative stress represents a ruthless complication of β-thalassemia that worsens the severity of that medical condition. There is no conclusive evidence on the best antioxidant used for that issue. Our earlier clinical study concluded that omega-3 and Manuka honey add-on to the conventional therapy had a potential therapeutic impact on reducing oxidative stress. However, there is no research evaluating their cost-effectiveness. This paper compares the cost-effectiveness of Omega-3 and Manuka honey supplementation to conventional therapy in treating oxidative stress among children with β-thalassemia major.

SUBJECTS AND METHODS

Cost-effectiveness evaluation of daily supplementation of Omega-3-Manuka honey and Manuka honey alone to the conventional therapy was performed. The economic evaluation was performed on data from a prospective 10-month randomized clinical trial. Fifty patients were recruited into the Omega-3-Manuka honey plus conventional therapy group, 50 patients were included in the Manuka honey alone plus conventional therapy group, and 50 patients receiving the conventional therapy alone served as a control group. Effectiveness measures from the randomized clinical trial were used to determine incremental effectiveness. Cost estimates were calculated from the healthcare payer's perspective. The analysis considered the improvement in oxidative stress biomarkers presented here as a percent change from baseline to determine the incremental effectiveness and cost for the treatment by both interventions.

RESULTS

Adding Omega-3 or Manuka honey to conventional therapy was a more cost-effective add-on than conventional treatment alone. Omega-3-Manuka honey was more cost-effective than Manuka honey alone in treating oxidative stress in that condition. Oxidative stress biomarkers were significantly reduced with both experimental medications compared to the conventional therapy alone.

CONCLUSIONS

The present study showed that using Manuka honey and Omega-3 as add-on treatments for oxidative stress in pediatric β-thalassemia disease could have significant cost-saving and clinical improvement.

Comparative effectiveness of adding omega-3 and Manuka honey combination to conventional therapy in preventing and treating oxidative stress in pediatric β-thalassemia major - a randomized clinical trial

OBJECTIVE

β-thalassemia major is an inherited hematological disorder with significant oxidative stress and iron overload. Oxidative stress results in several pathological complications, including cell death, tissue injury, organ dysfunction, and thyroid dysfunction. The present study examined the effectiveness of omega-3 and Manuka honey combination or Manuka honey alone to the conventional therapy (deferasirox, blood transfusion, and L-carnitine) used for preventing and managing oxidative stress or iron overload-induced oxidative stress conditions in pediatric β-thalassemic patients (type major).

PATIENTS AND METHODS

165 patients participated in this randomized, double-blind, standard therapy-controlled, parallel-design multisite trial. The patients were randomly allocated into three groups, receiving either 1,000 mg omega-3 fish oil [350 mg eicosapentaenoic acid (EPA) and 250 mg docosahexaenoic acid (DHA)] combined with Manuka honey lozenge (344 mg) daily or Manuka honey alone plus the conventional therapy for ten months. Plasma 8-iso-prostaglandin F2α (8-iso-PGF2α), Lactate dehydrogenase (LDH), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), CRP (C-reactive protein), ferritin level, and serum iron were determined at baseline and month 10.

RESULTS

Omega-3 and Manuka honey combination were a significant add-on to conventional therapy of β-thalassemia in reducing the oxidative stress condition. The combination of Omega-3 and Manuka honey reduced the level of F2-isoprostane(8-iso-PGF2α) significantly compared to the Manuka alone and the control groups. Additionally, they showed an antihemolytic action measured by reduced LDH level. The combination restored the patient's lipid profile (LDL-C and HDL-C) significantly compared to the control group. Manuka honey enhanced the action of omega-3 in reducing oxidative stress by reducing serum iron significantly compared to the control group.

CONCLUSIONS

Results showed that omega-3 + Manuka honey was more effective than Manuka alone or the conventional treatment alone in managing oxidative stress of β-thalassemic patients.

Automated detection of arterial landmarks and vascular occlusions in patients with acute stroke receiving digital subtraction angiography using deep learning

BACKGROUND

Digital subtraction angiography (DSA) is the gold-standard method of assessing arterial blood flow and blockages prior to endovascular thrombectomy.

OBJECTIVE

To detect anatomical features and arterial occlusions with DSA using artificial intelligence techniques.

METHODS

We included 82 patients with acute ischemic stroke who underwent DSA imaging and whose carotid terminus was visible in at least one run. Two neurointerventionalists labeled the carotid location (when visible) and vascular occlusions on 382 total individual DSA runs. For detecting the carotid terminus, positive and negative image patches (either containing or not containing the internal carotid artery terminus) were extracted in a 1:1 ratio. Two convolutional neural network architectures (ResNet-50 pretrained on ImageNet and ResNet-50 trained from scratch) were evaluated. Area under the curve (AUC) of the receiver operating characteristic and pixel distance from the ground truth were calculated. The same training and analysis methods were used for detecting arterial occlusions.

RESULTS

The ResNet-50 trained from scratch most accurately detected the carotid terminus (AUC 0.998 (95% CI 0.997 to 0.999), p<0.00001) and arterial occlusions (AUC 0.973 (95% CI 0.971 to 0.975), p<0.0001). Average pixel distances from ground truth for carotid terminus and occlusion localization were 63±45 and 98±84, corresponding to approximately 1.26±0.90 cm and 1.96±1.68 cm for a standard angiographic field-of-view.

CONCLUSION

These results may serve as an unbiased standard for clinical stroke trials, as optimal standardization would be useful for core laboratories in endovascular thrombectomy studies, and also expedite decision-making during DSA-based procedures.

Lung Transplantation in COVID 19 ARDS - Short Term Outcomes

Introduction

COVID-19 associated severe acute respiratory syndrome rapidly progress to irreversible lung injury, multiple organ failure and death. Lung transplantation is considered as the rescue therapy for these patients. Herein, we reported a case series of two successful life-saving bilateral lung transplantations for COVID-19-associated respiratory failure.

Case Report

Case 1: A 69-year-old male was admitted for hypoxia and altered mental status. He was diagnosed with COVID-19 pneumonia by abnormal CT findings and positive PCR result. After receiving a course of dexamethasone, convalescent plasma, remdesivir and broad-spectrum antibiotics, he remained to be profoundly hypoxic, requiring non-invasive ventilation. Following two negative PCR results, he underwent bilateral lung transplantation on day 57. He was discharged to rehab unit on postoperative day 26. No desaturation was observed with the 6-min walk test on 30-day follow-up.

Case 2: A 63-year-old male was presented with cough, and dyspnea. He was hemodynamically stable, SpO2 was 94%, chest x-ray was normal and tested positive for COVID-19. He was discharged home with dexamethasone and bronchodilators. However, he presented back on day 6 with worsening dyspnea. He was admitted and received a course of dexamethasone, remdesivir, convalescent plasma and broad-spectrum antibiotics. Due to persistent hypoxic respiratory failure, the patient underwent bilateral orthotopic lung transplantation on day 68. His postoperative course was complicated by primary graft dysfunction stage 3 and required open tracheostomy. His condition gradually improved and decannulated. He is currently on room air and able to walk 30 ft using a roller walker.

Summary

SARS-CoV-2 recovery is characterized by post inflammatory fibrosis and multi organ dysfunction. Lung transplantation can be successfully performed in patients with final stage respiratory failure of COVID-19 related pulmonary fibrosis.

A pilot study of avelumab in Epstein-Barr virus-associated gastric cancer

TPS473

Background: Gastric Cancer (GC) is the third most common cause of cancer related deaths worldwide. The median overall survival of patients with stage 4 disease is approximately 1 year. Current accepted treatment approach with chemotherapy is applied with little consideration for known genetic or biologic heterogeneity. Whilst immune-based approaches in GC look promising it is clear that single-agent PD1/PDL1 inhibition benefit a minority. We must clarify a means of identifying prospectively those patients who may benefit from this treatment. A recent landmark paper by The Cancer Genome Atlas (TCGA) proposed a classification of GC into four subtypes: Epstein-Barr-virus (EBV)-positive, microsatellite instable (MSI), chromosomal instable (CI), and genomically stable (GS). Two of the four – EBV and MSI subtypes – are likely to be immunogenic and amenable to PD1/PDL1 inhibition. Recent advances have shown EBV-positive tumors to be infiltrated by lymphocytes and be enriched for PDL1. Methods: This single centre single-arm pilot study in gastric or junctional adenocarcinoma will explore the hypothesis that administering anti-PDL1 therapy (Avelumab) in a prospectively identified population enriched for potential responders will result in improved outcomes. The anticipated frequency of EBV associated-GC (c10%) means that approximately N = 100 patients will be screened to identify N = 10 participants. If a positive signal for efficacy is seen this will provide a basis for a larger, multicentre study. Previously treated Patients with confirmation of stage 4 EBV- positive gastric or oesophago-gastric adenocarcinoma meeting eligibility criteria will be enrolled. Avelumab will be administered at a dose of 10mg/kg IV every 14days. Primary endpoint is to determine the 6-month progression free survival (PFS) of Avelumab in EBV-associated GC. Secondary endpoints include overall response rate, overall survival, median PFS time and feasibility/accrual rate at 12 months. Exploratory endpoints will be to evaluate changes in immune parameters in the peripheral blood over time. Kaplan-Meier methods for primary efficacy endpoint with two-tailed one-sample proportion test will be used to evaluate the evidence to reject the null hypothesis. Clinical trial information: 2018-002085-39.

Discussion of “Evidence-based Health Informatics: How Do We Know What We Know?”

This article is part of a For-Discussion-Section of Methods of Information in Medicine about the paper “Evidence-based Health Informatics: How Do We Know What We Know?” written by Elske Ammenwerth [1]. It is introduced by an editorial. This article contains the combined commentaries invited to independently comment on the Ammenwerth paper. In subsequent issues the discussion can continue through letters to the editor.

With these comments on the paper “Evidence-based Health Informatics: How do we know what we know?”, written by Elske Ammenwerth [1], the journal seeks to stimulate a broad discussion on the challenges of evaluating information processing and information technology in health care. An international group of experts has been invited by the editor of Methods to comment on this paper. Each of the invited commentaries forms one section of this paper.

Discussion of “Biomedical Infor -matics: We Are What We Publish”

This article is part of a For-Discussion-Section of Methods of Information in Medicine about the paper "Biomedical Informatics: We Are What We Publish", written by Peter L. Elkin, Steven H. Brown, and Graham Wright. It is introduced by an editorial. This article contains the combined commenta -ries invited to independently comment on the Elkin et al. paper. In subsequent issues the discussion can continue through letters to the editor.

Discussion of "Biomedical informatics: we are what we publish"

This article is part of a For-Discussion-Section of Methods of Information in Medicine about the paper "Biomedical Informatics: We Are What We Publish", written by Peter L. Elkin, Steven H. Brown, and Graham Wright. It is introduced by an editorial. This article contains the combined commentaries invited to independently comment on the Elkin et al. paper. In subsequent issues the discussion can continue through letters to the editor.

[Satisfaction with dental care from the patient's perspective - the dental-ZAP-V1]

BACKGROUND

Patient satisfaction is a central topic in quality management in outpatient dental care. The ZAP questionnaire was validated to explore patient satisfaction in general and specialist outpatient settings. This study aims at assessing the psychometric properties of the ZAP in dental care.

METHODS

A minimally modified version of the ZAP consisting of 4 domains (office organisation, cooperation, interaction, information) was administered in personal interviews to a population-based sample. Descriptive, exploratory and confirmatory psychometric analyses were conducted with random subsets of the study sample.

RESULTS

The study population comprised 1 773 subjects with at least one dental visit during their lifetime (mean age=50 years, female=51.6%). The exploratory factor analysis identified 3 subscales (office organisation, interaction, information). Based on these results, items of the subscale "cooperation" were excluded from further analyses. The remaining items had a medium difficulty of 0.75, all item-total-correlations were above 0.4. Missing values ranged between 2.3% and 28.7%. Cronbach's alpha ranged between 0.79 and 0.95. After introduction of 3 residual correlations, the confirmatory factor analyses reached a good model fit (TLI: 0.97; CFI: 0.97, RMSEA: 0.06). Partial standardised factor loadings ranged between 0.77 and 0.87. The 3 latent factors were highly correlated. There was a positive correlation between the 3 subscales and global patient satisfaction with the dentist.

CONCLUSION

The psychometric assessment can be used in the 3 modified subscales (office organisation, interaction, and information) to assess patient satisfaction with dental care. To assess dentist's competence in relation to dental anxiety and pain as well as shared decision making new scales specific to dental care should be explored.

Dying to give birth: the Pakistan Liaison Committee's strategies to improve maternal health in Pakistan

Pakistan has one of the worst maternal mortality ratios worldwide: 260-490 women die for every 100,000 live births in Pakistan. The Pakistan Liaison Group (PLG) was formed to work with and through the international office of the Royal College of Obstetricians and Gynaecologists (RCOG). It works with the RCOG representative committee in Pakistan to improve the health of women. It aims to contribute to improving maternal morbidity and mortality through strategies directed at improving the education and training of health professionals. In addition, the PLG aims to promote changes in the legislature to allow for the notification of maternal deaths so that accurate figures can be obtained, and so that health parameters can be accurately assessed and, in the long term, a confidential enquiry into maternal deaths can be initiated.

Biomedical and Health Informatics Education and Research at the Information Technology Institute in Egypt

During the last decade, Egypt has experienced a revolution in the field of Information and Communication Technology (ICT) that has had a corresponding impact on the field of healthcare.

Since 1993, the Information Technology Institute (ITI) has been leading the development of the Information Technology (IT) professional training and education in Egypt to produce top quality IT professionals who are considered now the backbone of the IT revolution in Egypt. For the past five years, ITI has been adopting the objective of building high caliber health professionals who can effectively serve the ever-growing information society.

Academic links have been established with internationally renowned universities, e.g., Oregon Health and Science University (OHSU) in US, University of Leipzig in Germany, in addition those with the Egyptian Fellowship Board in order to enrich ITI Medical Informatics Education and Research.

The ITI Biomedical and Health Informatics (BMHI) education and training programs target fresh graduates as well as lifelong learners. Therefore, the program’s learning objectives are framed within the context of the four specialization tracks: Healthcare Man- agement (HCM), Biomedical Informatics Research (BMIR), Bioinformatics Professional (BIP), and Healthcare Professional (HCP). The ITI BMHI research projects tackle a wide-range of current chal- lenges in this field, such as knowledge management in healthcare, providing tele-consultation services for diagnosis and treatment of infectious diseases for underserved regions in Egypt, and exploring the cultural and educational aspects of Nanoinformatics.

Since 2006, ITI has been positively contributing to de- velop the discipline of BMHI in Egypt in order to support improved healthcare services .

Biomedical and health informatics education and research at the Information Technology Institute in Egypt

OBJECTIVES

During the last decade, Egypt has experienced a revolution in the field of Information and Communication Technology (ICT) that has had a corresponding impact on the field of healthcare. Since 1993, the Information Technology Institute (ITI) has been leading the development of the Information Technology (IT) professional training and education in Egypt to produce top quality IT professionals who are considered now the backbone of the IT revolution in Egypt. For the past five years, ITI has been adopting the objective of building high caliber health professionals who can effectively serve the ever-growing information society.

METHODS

Academic links have been established with internationally renowned universities, e.g., Oregon Health and Science University (OHSU) in US, University of Leipzig in Germany, in addition those with the Egyptian Fellowship Board in order to enrich ITI Medical Informatics Education and Research.

RESULTS

The ITI Biomedical and Health Informatics (BMHI) education and training programs target fresh graduates as well as life-long learners. Therefore, the program's learning objectives are framed within the context of the four specialization tracks: Healthcare Management (HCM), Biomedical Informatics Research (BMIR), Bioinformatics Professional (BIP), and Healthcare Professional (HCP). The ITI BMHI research projects tackle a wide-range of current challenges in this field, such as knowledge management in healthcare, providing tele-consultation services for diagnosis and treatment of infectious diseases for underserved regions in Egypt, and exploring the cultural and educational aspects of Nanoinformatics.

CONCLUSION

Since 2006, ITI has been positively contributing to develop the discipline of BMHI in Egypt in order to support improved healthcare services.

A toxicological evaluation of inhaled solid lipid nanoparticles used as a potential drug delivery system for the lung

Inhalation is a non-invasive approach for both local and systemic drug delivery. This study aimed to define the therapeutic window for solid lipid nanoparticles (SLNs) as a drug delivery system by inhalation from a toxicological point of view. To estimate the toxic dose of SLNs in vitro, A549 cells and murine precision-cut lung slices (PCLS) were exposed to increasing concentrations of SLNs. The cytotoxic effect of SLNs on A549 cells was evaluated by MTT and NRU assays. Viability of lung tissue was determined with WST assay and by life/dead staining using calcein AM/EthD-1 for confocal microscopy (CLSM) followed by quantitative analysis with IMARIS. Inflammation was assessed by measuring chemokine KC and TNF-alpha levels. The in vivo effects were determined in a 16-day repeated-dose inhalation toxicity study using female BALB/c mice, which were daily exposed to different concentrations of SLN30 aerosols (1-200 microg deposit dose). Local inflammatory effects in the respiratory tract were evaluated by determination of total protein content, LDH, chemokine KC, IL-6, and differential cell counts, performed on days 4, 8, 12, and 16 in bronchoalveolar lavage fluid. Additionally, a histopathological evaluation of toxicologically relevant organs was accomplished. The in vitro and ex vivo dose finding experiments showed toxic effects beginning at concentrations of about 500 microg/ml. Therefore, we used 1-200 microg deposit doses/animal for the in vivo experiments. Even after 16 days of challenge with a 200-microg deposit dose, SLNs induced no significant signs of inflammation. We observed no consistent increase in LDH release, protein levels, or other signs of inflammation such as chemokine KC, IL-6, or neutrophilia. In contrast, the particle control (carbon black) caused inflammatory and cytotoxic effects at corresponding concentrations. These results confirm that repeated inhalation exposure to SLN30 at concentrations lower than a 200-microg deposit dose is safe in a murine inhalation model.

Evaluating wastewater-induced plant genotoxicity using randomly amplified polymorphic DNA

Wastewater often contains genotoxic substances that can resist different stages of the treatment process. In the present study, randomly amplified polymorphic DNA technology was applied to evaluate the genotoxic effects of wastewater (treated and raw) irrigation on oat plants (Avena sativa). RAPD profiles obtained showed that both treated and raw wastewater (RWW) were having genotoxic effects on oat plants. This was apparent by the appearance/disappearance of bands in the treatments compared with the control plants. From the 15 primers used, 186 bands were obtained with an average of 12.4 bands per primer. Irrigating plants with RWW caused 51 new bands to appear and 19 to disappear. Treated wastewater (TWW) caused only 16 new bands and the loss of 17 bands. This makes TWW less genotoxic than RWW. The Euclidean distances shown on the dendrogram, revealed the presence of two clusters according to dissimilarity values. One cluster contained the control plants and those irrigated with TWW, whereas the second contained the plants irrigated with RWW. Similarity indices calculated between the treatments and the control plants showed that the control and the plants irrigated with TWW had a similarity index of 0.87, the control and plants irrigated with RWW 0.73 and between the treatments 0.75.

Complex regional pain syndrome with special emphasis on the knee

Complex regional pain syndrome is characterised by an exaggerated response to injury in a limb with intense prolonged pain, vasomotor disturbance, delayed functional recovery and trophic changes. This review describes the current knowledge of the condition and outlines the methods of treatment available with particular emphasis on the knee.

Soft tissue sarcomas: are current referral guidelines sufficient?

INTRODUCTION

To investigate the adequacy of current early referral guidelines for patients with extremity soft tissue sarcomas.

PATIENTS & METHODS

365 patients with confirmed soft tissue sarcomas were evaluated. Data were collected prospectively and included the length of history and the presence of features in current guidelines suggestive of malignancy (pain, rapidity of growth, depth and tumour size). Statistical analysis included the t-test, ANOVA and the Chi test.

RESULTS

Deep tumours were the commonest (306 patients with deep tumours). Pain was the least consistent feature (176 patients with pain). 345 patients with one or more of the guideline features had an average history of 19.86 months, 238 of these were seen after more than 3 months.

CONCLUSION

Although the majority of soft tissue sarcomas in our patients had one or more of the clinical guideline features, there was still an unacceptable delay in referring these patients to a specialist unit. The referral guidelines should be modified with special emphasis on depth, which is the most sensitive, followed by size and a history of rapid growth. This combined with increased awareness of these guidelines and a well-advertised, open-access clinic linked to a specialist unit should allow for a more rapid evaluation of soft tissue tumours.

Internationalization of Healthcare Applications: A Generic Approach for PACS Workstations

Objectives: Along with the revolution of information technology and the increasing use of computers worldwide, software providers recognize the emerging need for internationalized, or global, software applications. The importance of internationalization comes from its benefits such as addressing a broader audience, making the software applications more accessible, easier to use, more flexible to support and providing users with more consistent information. In addition, some governmental agencies, e.g., in Spain, accept only fully localized software. Although the healthcare communication standards, namely, Digital Imaging and Communication in Medicine (DICOM) and Health Level Seven (HL7) support wide areas of internationalization, most of the implementers are still protective about supporting the complex languages. This paper describes a generic internationalization approach for Picture Archiving and Communication System (PACS) workstations.

Methods: The Unicode standard is used to internationalize the application user interface. An encoding converter was developed to encode and decode the data between the rendering module (in Unicode encoding) and the DICOM data (in ISO 8859 encoding). An integration gateway was required to integrate the inter-nationalized PACS components with the different PACS installations. To introduce a pragmatic example, the described approach was applied to the CHILI PACS workstation.

Results: The approach has enabled the application to handle the different internationalization aspects transparently, such as supporting complex languages, switching between different languages at runtime, and supporting multilingual clinical reports.

Conclusions: In the healthcare enterprises, internationalized applications play an essential role in supporting a seamless flow of information between the heterogeneous multivendor information systems.

Internationalization of healthcare applications: a generic approach for PACS workstations

OBJECTIVES

Along with the revolution of information technology and the increasing use of computers world-wide, software providers recognize the emerging need for internationalized, or global, software applications. The importance of internationalization comes from its benefits such as addressing a broader audience, making the software applications more accessible, easier to use, more flexible to support and providing users with more consistent information. In addition, some governmental agencies, e.g., in Spain, accept only fully localized software. Although the healthcare communication standards, namely, Digital Imaging and Communication in Medicine (DICOM) and Health Level Seven (HL7) support wide areas of internationalization, most of the implementers are still protective about supporting the complex languages. This paper describes a generic internationalization approach for Picture Archiving and Communication System (PACS) workstations.

METHODS

The Unicode standard is used to internationalize the application user interface. An encoding converter was developed to encode and decode the data between the rendering module (in Unicode encoding) and the DICOM data (in ISO 8859 encoding). An integration gateway was required to integrate the internationalized PACS components with the different PACS installations. To introduce a pragmatic example, the described approach was applied to the CHILI PACS workstation.

RESULTS

The approach has enabled the application to handle the different internationalization aspects transparently, such as supporting complex languages, switching between different languages at runtime, and supporting multilingual clinical reports.

CONCLUSIONS

In the healthcare enterprises, internationalized applications play an essential role in supporting a seamless flow of information between the heterogeneous multivendor information systems.

Management of knee arthroscopy portals

Although the use of suture material for closure of knee arthroscopy portals has decreased, many surgeons continue to use adhesive tape, assuming this is superior to leaving them open. We have investigated two modalities of portal management after knee arthroscopy, the open method and the use of adhesive tape, documenting wound healing, complications and patient satisfaction. Eighty-seven patients (92 knees) were included in this study, 183 portals were involved. Sixty portals (30 knees) were closed with adhesive tape and 123 portals (62 knees) were left open. Follow up was at 2 weeks and at a further 6 weeks post operatively for those with a complication. In the adhesive tape group there were 6 portals with a complication (10%). In the open group there were 13 portals with a complication (10.56%). There were no major or long term complications and no significant difference between the two methods of treatment (P = 0.908 for portals, P = 0.954 for knees). We concluded that leaving knee athroscopy wounds open is an acceptable method of management when compared to adhesive tape.

Population pharmacokinetics of perhexiline from very sparse, routine monitoring data

Using NONMEM, the population pharmacokinetics of perhexiline were studied in 88 patients (34 F, 54 M) who were being treated for refractory angina. Their mean +/- SD (range) age was 75 +/- 9.9 years (46-92), and the length of perhexiline treatment was 56 +/- 77 weeks (0.3-416). The sampling time after a dose was 14.1 +/- 21.4 hours (0.5-200), and the perhexiline plasma concentrations were 0.39 +/- 0.32 mg/L (0.03-1.56). A one-compartment model with first-order absorption was fitted to the data using the first-order (FO) approximation. The best model contained 2 subpopulations (obtained via the $MIXTURE subroutine) of 77 subjects (subgroup A) and 11 subjects (subgroup B) that had typical values for clearance (CL/F) of 21.8 L/h and 2.06 L/h, respectively. The volumes of distribution (V/F) were 1470 L and 260 L, respectively, which suggested a reduction in presystemic metabolism in subgroup B. The interindividual variability (CV%) was modeled logarithmically and for CL/F ranged from 69.1% (subgroup A) to 86.3% (subgroup B). The interindividual variability in V/F was 111%. The residual variability unexplained by the population model was 28.2%. These results confirm and extend the existing pharmacokinetic data on perhexiline, especially the bimodal distribution of CL/F manifested via an inherited deficiency in hepatic and extrahepatic CYP2D6 activity.

Expedient microdetermination of itraconazole and hydroxyitraconazole in plasma by high-performance liquid chromatography with fluorescence detection

The authors describe a useful and rapid micromethod for the analysis of itraconazole (ITZ) and its active metabolite hydroxyitraconazole (HIT) in human plasma. After a simple deproteinization of 100 microL plasma with acetonitrile, the drug, its metabolite, and an internal standard (IS, ketoconazole) were separated on an 8 mm x 10 cm NovaPak (Waters Associates; Milford, MA) C(18) 4-microm particle-size radial compression cartridge. The compounds of interest were detected using a fluorescence detector with the excitation wavelength set at 260 nm and the emission at 365 nm. The mobile phase consisted of 420 mL water adjusted to a pH of 2.5 with phosphoric acid, 580 mL acetonitrile, and 100 microL triethylamine, which was delivered at a flow rate of 3.0 mL/min. This expedient and rugged method is being used to monitor therapeutic levels in bone marrow transplant recipients who are taking the drug for prophylaxis.

Sensitive assay for the determination of cefazolin or ceftriaxone in plasma utilizing LC

A rapid, specific and very sensitive liquid chromatographic assay using standard ultraviolet detection has been developed to measure cefazolin (CFZ) or ceftriaxone (CFX) in small samples (200 microl) of plasma using either drug as the internal standard for measurement of the other. A rapid extraction was performed using C18 bonded Sep Pak cartridges with high extraction efficiency for both drugs. The chromatographic system employed the use of a Nova-Pak C18 4-microm cartridge with a radial compression system preceded by a Guard-Pak with a C18 insert. The mobile phase consisted of an aqueous solution containing 10 mM of dibasic potassium phosphate and 10 mM cetyltrimethylammonium bromide (pH 6.5) with acetonitrile (73:27 v/v). The drug and internal standard (CFZ/CFX) were detected using a UV detector set at a wavelength of 274 nm. Assay results were linearly related to the concentration (r > 0.997) for the wide range which was examined (0.005-120 microg/ml) for either drug. We report the precision, accuracy, recovery, linearity, sensitivity and specificity of this assay. The intra-run and inter-run CV was less than 9.02%. This method is currently being used for clinical therapeutic monitoring and pharmacokinetic studies of CFZ and CFX in patients undergoing cesarean section.

Effect of repeated dosing on the pharmacokinetics of oral fluconazole in bone marrow transplant patients

We examined the pharmacokinetics of fluconazole in 11 bone marrow transplant patients after multiple oral daily dose of 200 mg of this drug. Blood was sampled at different intervals on day 1, day 13, and day 27. No dose was given on day 2, day 14, and day 28 to allow the concentration-time data to be collected over 48 hours. The 24 hour urine was also collected, and fluconazole was analyzed in both plasma and urine by a high performance liquid chromatography. The plasma concentration-time data were best described by the one-compartment model with first-order absorption. The overall inter-day change and the difference between day 1 and day 27 in the rate constant for absorption (ka), peak plasma concentration (Cmax), through plasma concentration (Cmin), time-to-peak (tmax), area-under-the-curve 0-24 (AUC0-24), rate constant for elimination (ka), mean residence time after oral administration (MRTor), and fraction of the dose excreted unchanged in urine 24 hours (fu24) were significant (P < or = 0.0029 and P < or = 0.01, respectively). However, the difference between day 1 and day 13 was significant (P < or = 0.05) only in ka, tmax, Cmax, Cmin, and AUC0-24, and between day 13 and day 27 was significant (P < or = 0.05) only in ka, Cmin, ka, and MRTor. There was no significant inter-day change in the renal clearance. The significant (P < or = 0.05) increases in Cmax, Cmin, and AUC0-24 after the dose given on day 13 as compared with day 1, and in Cmin on day 27 as compared with day 13 indicate that, in contrast to volunteers, the steady state condition was not reached on day 13 and possibly not on day 27 in these patients. This perhaps should be taken into account when prescribing fluconazole to seriously ill patients.

Experience with methicillin resistant Staphylococcus aureus at the Nairobi Hospital

The problem of MRSA was recognised in mid year of 1996 among both in and out patients at the Nairobi Hospital. The Infection Control Committee, through the microbiology section of the laboratory, immediately accelerated the surveillance programme which included culturing all the wards, beddings, sinks, utensils, furniture and staff. The source was identified and disinfectant methods were modified to eradicate the infection from the community. Relentless fight against the micro-organism through the recommended methods resulted in no more cases at the end of the year. Nosocomial infections must be recognised by all hospitals which must have viable infection control programmes. The Nairobi hospital has an active and on-going infection control programme which enabled this problem to be identified and solved in a timely manner.