Investigating the Potential for Clinical Decision Support in Sub-Saharan Africa With AFYA (Artificial Intelligence-Based Assessment of Health Symptoms in Tanzania): Protocol for a Prospective, Observational Pilot Study

BACKGROUND

Low- and middle-income countries face difficulties in providing adequate health care. One of the reasons is a shortage of qualified health workers. Diagnostic decision support systems are designed to aid clinicians in their work and have the potential to mitigate pressure on health care systems.

OBJECTIVE

The Artificial Intelligence-Based Assessment of Health Symptoms in Tanzania (AFYA) study will evaluate the potential of an English-language artificial intelligence-based prototype diagnostic decision support system for mid-level health care practitioners in a low- or middle-income setting.

METHODS

This is an observational, prospective clinical study conducted in a busy Tanzanian district hospital. In addition to usual care visits, study participants will consult a mid-level health care practitioner, who will use a prototype diagnostic decision support system, and a study physician. The accuracy and comprehensiveness of the differential diagnosis provided by the diagnostic decision support system will be evaluated against a gold-standard differential diagnosis provided by an expert panel.

RESULTS

Patient recruitment started in October 2021. Participants were recruited directly in the waiting room of the outpatient clinic at the hospital. Data collection will conclude in May 2022. Data analysis is planned to be finished by the end of June 2022. The results will be published in a peer-reviewed journal.

CONCLUSIONS

Most diagnostic decision support systems have been developed and evaluated in high-income countries, but there is great potential for these systems to improve the delivery of health care in low- and middle-income countries. The findings of this real-patient study will provide insights based on the performance and usability of a prototype diagnostic decision support system in low- or middle-income countries.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04958577; http://clinicaltrials.gov/ct2/show/NCT04958577.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/34298.

Study protocol for a pilot prospective, observational study investigating the condition suggestion and urgency advice accuracy of a symptom assessment app in sub-Saharan Africa: the AFYA-'Health' Study

INTRODUCTION

Due to a global shortage of healthcare workers, there is a lack of basic healthcare for 4 billion people worldwide, particularly affecting low-income and middle-income countries. The utilisation of AI-based healthcare tools such as symptom assessment applications (SAAs) has the potential to reduce the burden on healthcare systems. The purpose of the AFYA Study (AI-based Assessment oF health sYmptoms in TAnzania) is to evaluate the accuracy of the condition suggestions and urgency advice provided by a user on a Swahili language Ada SAA.

METHODS AND ANALYSIS

This study is designed as an observational prospective clinical study. The setting is a waiting room of a Tanzanian district hospital. It will include patients entering the outpatient clinic with various conditions and age groups, including children and adolescents. Patients will be asked to use the SAA before proceeding to usual care. After usual care, they will have a consultation with a study-provided physician. Patients and healthcare practitioners will be blinded to the SAA's results. An expert panel will compare the Ada SAA's condition suggestions and urgency advice to usual care and study provided differential diagnoses and triage. The primary outcome measures are the accuracy and comprehensiveness of the Ada SAA evaluated against the gold standard differential diagnoses.

ETHICS AND DISSEMINATION

Ethical approval was received by the ethics committee (EC) of Muhimbili University of Health and Allied Sciences with an approval number MUHAS-REC-09-2019-044 and the National Institute for Medical Research, NIMR/HQ/R.8c/Vol. I/922. All amendments to the protocol are reported and adapted on the basis of the requirements of the EC. The results from this study will be submitted to peer-reviewed journals, local and international stakeholders, and will be communicated in editorials/articles by Ada Health.

TRIAL REGISTRATION NUMBER

NCT04958577.

Dementia patients have greater anti-cholinergic drug burden on discharge from hospital: A multicentre cross-sectional study

Introduction

Anticholinergic medications block cholinergic transmission. The central effects of anticholinergic drugs can be particularly marked in patients with dementia. Furthermore, anticholinergics antagonise the effects of cholinesterase inhibitors, the main dementia treatment.

Objectives

This study aimed to assess anticholinergic drug prescribing among dementia patients before and after admission to UK acute hospitals.

Methods

352 patients with dementia were included from 17 hospitals in the UK. All were admitted to surgical, medical or Care of the Elderly wards in 2019. Information about patients’ prescriptions were recorded on a standardised form. An evidence-based online calculator was used to calculate the anticholinergic drug burden of each patient. The correlation between two subgroups upon admission and discharge was tested with Spearman’s Rank Correlation.

Results

Table 1 shows patient demographics. On admission, 37.8% of patients had an anticholinergic burden score ≥1 and 5.68% ≥3. At discharge, 43.2% of patients had an anticholinergic burden score ≥1 and 9.1% ≥3. The increase was statistically significant (rho 0.688; p=2.2x10-16). The most common group of anticholinergic medications prescribed at discharge were psychotropics (see Figure 1). Among patients prescribed cholinesterase inhibitors, 44.9% were also taking anticholinergic medications.

Conclusions

This multicentre cross-sectional study found that people with dementia are frequently prescribed anticholinergic drugs, even if also taking cholinesterase inhibitors, and are significantly more likely to be discharged with a higher anticholinergic drug burden than on admission to hospital.

Conflict of interest

This project was planned and executed by the authors on behalf of SPARC (Student Psychiatry Audit and Research Collaborative). We thank the National Student Association of Medical Research for allowing us use of the Enketo platform. Judith Harrison was su

A distinctive release profile of vancomycin and tobramycin from a new and injectable polymeric dicalcium phosphate dehydrate cement (P-DCPD)

A novel injectable polymeric dicalcium phosphate dehydrate (P-DCPD) cement was developed with superior mechanical strength and excellent cohesion. The purpose of this study was to assess the in vitro performance of P-DCPD loaded with vancomycin (VAN-P), tobramycin (TOB-P) and combination of both (VAN/TOB-P) (10%, w/w). There is a distinctive release profile between VAN and TOB. VAN-P showed decreased initial burst (<30% within 3 d) and sustained VAN release (76% in 28 d). In the presence of TOB (VAN/TOB-P), >90% of VAN was released within 3 d (p < 0.05). Slow and limited TOB release was observed both in TOB-P (<5%) and in TOB/VAN-P (<1%) over 28 d. Zone of inhibition (ZOI) of Staphylococcus aureus growth showed that eluents collected from VAN-P had stronger and longer ZOI (28 d) than that from TOB-P (14 d, p < 0.05). Direct contact of VAN-P, TOB-P and VAN/TOB-P cements displayed persistent and strong ZOI for >3 weeks. Interestingly, the cement residues (28 d after drug release) still maintained strong ZOI ability. P-DCPD with or without antibiotics loading were nontoxic and had no inferior impacts on the growth of osteoblastic MC3T3 cells. VAN-P and TOB-P were injectable. No significant influence on setting time was observed in both VAN-P (11.7 ± 1.9 min) and VAN/TOB-P (10.8 ± 1.5 min) as compared to control (12.2 ± 2.6 min). We propose that a distinctive release profile of VAN and TOB observed is mainly due to different distribution pattern of VAN and TOB within P-DCPD matrix. A limited release of TOB might be due to the incorporation of TOB inside the crystalline lattice of P-DCPD crystals. Our data supported that the bactericidal efficacy of antibiotics-loaded P-DCPD is not only depend on the amount and velocity of antibiotics released, but also probably more on the direct contact of attached bacteria on the degrading cement surface.

Travel restrictions and infectious disease outbreaks

BACKGROUND

A key purpose of the International Health Regulations (IHR) is to prevent unwarranted interruptions to trade and travel during large and/or transnational infectious disease outbreaks. Nevertheless, such outbreaks continue to disrupt the travel industry. This aspect of the IHR has received little attention in the academic literature despite its considerable impact on affected States and commercial activity. This article outlines the challenges and gaps in knowledge regarding the relationship between outbreaks and the travel sector and discusses the opportunities for further research and policy work to overcome these challenges.

METHODOLOGY

We conducted a literature review on the relationship between outbreaks and travel restrictions, with a particular focus on the 2014-16 Ebola epidemic in West Africa. This review was complemented by an expert roundtable at Chatham House and further supported by case studies and qualitative interviews.

RESULTS

Numerous travel stakeholders are affected by, and affect, large-scale infectious disease outbreaks. These stakeholders react in different ways: peer pressure plays an important role for both governments and the travel sector, and the reactions of the media and public influence and are influenced by these stakeholders. While various data sources on travel are available, and World Health Organization is mandated to work with States, there is no recognized coordinating body to disseminate timely, consistent, reliable and authoritative information and best practices to all stakeholders.

CONCLUSION

This article highlights the interdependent relationship between various travel stakeholders. The reasons for interruption of travel during the 2014-16 Ebola outbreak were complex, with decisions by States only partly contributing to the cessation. Decisions by non-state actors, particularly the travel industry itself, contributed significantly and were based on a variety of factors. Further research, analysis and policy development are required to mitigate the health and economic consequences of infectious disease outbreaks. Any further research will also need to take account of COVID-19 travel-related issues.

Prognostic factors for diffuse large B-cell lymphoma in the R(X)CHOP era

BACKGROUND

The introduction of rituximab (R) to conventional CHOP chemotherapy for newly diagnosed diffuse large B-cell lymphoma (DLBCL) led to an unequivocal improvement in survival, establishing RCHOP as the standard of care. Still, nearly 40% of DLBCL patients will eventually die of relapsed disease. Efforts to improve outcomes by addition of new biologic agents (X) to the RCHOP backbone are underway. In this era of R(X)CHOP, it is imperative to develop prognostic and predictive markers, not only to identify patients who will suffer a particularly aggressive course, but also to accurately select patients for clinical trials from which they will most benefit.

DESIGN

The following review was undertaken to describe prognostic factors in DLBCL, with emphasis on markers that are accurate, relatively available, and clinically applicable in 2014.

RESULTS

The International Prognostic Index retains its validity in the era of RCHOP, although with limited ability to predict those with <50% chance of long-term survival. Gene expression profiling has provided novel insights into the biology of DLBCL and led to the development of immunohistochemistry (IHC) algorithms that are in routine practice. Identification of a 'double-hit' (DH) lymphoma by fluorescent in situ hybridization with aberrations involving MYC and/or BCL2 and BCL6 genes has important implications due to its extremely dismal prognosis with RCHOP. Other markers such as the absolute lymphocyte count (ALC), serum immunoglobulin free light chains, vitamin D levels, serum cytokines/chemokines, and imaging with positron emission tomography (PET) have all shown promise as future predictive/prognostic tests.

CONCLUSIONS

The future for new treatment options in DLBCL is promising with current clinical trials testing novel targeted agents such as bortezomib, lenalidomide, and ibrutinib as the 'X' in R(X)CHOP. Predictive factors are required to select and randomize patients appropriately for these trials. We envision the day when 'X' will be chosen based on the biological characteristics of the tumor.

Survival and prognosis among 1545 patients with contemporary polycythemia vera: an international study

Under the auspices of an International Working Group, seven centers submitted diagnostic and follow-up information on 1545 patients with World Health Organization-defined polycythemia vera (PV). At diagnosis, median age was 61 years (51% females); thrombocytosis and venous thrombosis were more frequent in women and arterial thrombosis and abnormal karyotype in men. Considering patients from the center with the most mature follow-up information (n=337 with 44% of patients followed to death), median survival (14.1 years) was significantly worse than that of the age- and sex-matched US population (P<0.001). In multivariable analysis, survival for the entire study cohort (n=1545) was adversely affected by older age, leukocytosis, venous thrombosis and abnormal karyotype; a prognostic model that included the first three parameters delineated risk groups with median survivals of 10.9-27.8 years (hazard ratio (HR), 10.7; 95% confidence interval (CI): 7.7-15.0). Pruritus was identified as a favorable risk factor for survival. Cumulative hazard of leukemic transformation, with death as a competing risk, was 2.3% at 10 years and 5.5% at 15 years; risk factors included older age, abnormal karyotype and leukocytes ≥15 × 10(9)/l. Leukemic transformation was associated with treatment exposure to pipobroman or P32/chlorambucil. We found no association between leukemic transformation and hydroxyurea or busulfan use.

Bowel perforation in intestinal lymphoma: incidence and clinical features

BACKGROUND

Perforation is a serious life-threatening complication of lymphomas involving the gastrointestinal (GI) tract. Although some perforations occur as the initial presentation of GI lymphoma, others occur after initiation of chemotherapy. To define the location and timing of perforation, a single-center study was carried out of all patients with GI lymphoma.

PATIENTS AND METHODS

Between 1975 and 2012, 1062 patients were identified with biopsy-proven GI involvement with lymphoma. A retrospective chart review was undertaken to identify patients with gut perforation and to determine their clinicopathologic features.

RESULTS

Nine percent (92 of 1062) of patients developed a perforation, of which 55% (51 of 92) occurred after chemotherapy. The median day of perforation after initiation of chemotherapy was 46 days (mean, 83 days; range, 2-298) and 44% of perforations occurred within the first 4 weeks of treatment. Diffuse large B-cell lymphoma (DLBCL) was the most common lymphoma associated with perforation (59%, 55 of 92). Compared with indolent B-cell lymphomas, the risk of perforation was higher with aggressive B-cell lymphomas (hazard ratio, HR = 6.31, P < 0.0001) or T-cell/other types (HR = 12.40, P < 0.0001). The small intestine was the most common site of perforation (59%).

CONCLUSION

Perforation remains a significant complication of GI lymphomas and is more frequently associated with aggressive than indolent lymphomas. Supported in part by University of Iowa/Mayo Clinic SPORE CA97274 and the Predolin Foundation.

Histoid leprosy: an uncommon variant of lepromatous leprosy

Histoid leprosy is an uncommon variant of lepromatous leprosy with characteristic clinical, immunologic and bacteriologic finding. Histoid leprosy can be eliminated by early diagnosis and complete treatment. Journal of College of Medical Sciences-Nepal,2011,Vol-6,No-4, 76-78 DOI: http://dx.doi.org/10.3126/jcmsn.v6i4.6733

Refined cytogenetic-risk categorization for overall and leukemia-free survival in primary myelofibrosis: a single center study of 433 patients

We have previously identified sole +9, 13q- or 20q-, as ‘favorable' and sole +8 or complex karyotype as ‘unfavorable' cytogenetic abnormalities in primary myelofibrosis (PMF). In this study of 433 PMF patients, we describe additional sole abnormalities with favorable (chromosome 1 translocations/duplications) or unfavorable (−7/7q-) prognosis and also show that other sole or two abnormalities that do not include i(17q), −5/5q-, 12p-, inv(3) or 11q23 rearrangement are prognostically aligned with normal karyotype, which is prognostically favorable. These findings were incorporated into a refined two-tired cytogenetic-risk stratification: unfavorable and favorable karyotype. The respective 5-year survival rates were 8 and 51% (hazard ratio (HR): 3.1, 95% confidence interval (CI): 2.2–4.3; P<0.0001). Multivariable analysis confirmed the International Prognostic Scoring System (IPSS)-independent prognostic value of cytogenetic-risk categorization and also identified thrombocytopenia (platelets <100 × 10⁹/l) as another independent predictor of inferior survival (P<0.0001). A similar multivariable analysis showed that karyotype (P=0.001) and platelet count (P=0.04), but not IPSS (P=0.27), predicted leukemia-free survival; the 5-year leukemic transformation rates for unfavorable versus favorable karyotype were 46 and 7% (HR: 5.5, 95% CI: 2.5–12.0; P<0.0001). This study provides the rationale and necessary details for incorporating cytogenetic findings and platelet count in future prognostic models for PMF.

Mad honey poisoning: a rare case report of seven cases

The cause of mad honey poisoning is the toxin grayanotoxin, found in honey obtained from the nectar of Rhododendron species on the higher altitudes. This case report is about seven cases of grayanotoxin poisoning that occurred after consumption of wild honey that was brought from the Himalayan belt of Nepal. Most of them presented with symptoms of blurring of vision, diplopia, nasea and vomiting and two of them presented with symptoms of cardiac depression. All of the cases responded well to intravenous fluid and/or pressor agents while none proved to be fatal

Interbody fusion with allograft and rhBMP-2 leads to consistent fusion but early subsidence

We carried out a prospective study to determine whether the addition of a recombinant human bone morphogenetic protein (rhBMP-2) to a machined allograft spacer would improve the rate of intervertebral body fusion in the spine. We studied 77 patients who were to undergo an interbody fusion with allograft and instrumentation. The first 36 patients received allograft with adjuvant rhBMP-2 (allograft/rhBMP-2 group), and the next 41, allograft and demineralised bone matrix (allograft/demineralised bone matrix group). Each patient was assessed clinically and radiologically both pre-operatively and at each follow-up visit using standard methods. Follow-up continued for two years. Every patient in the allograft/rhBMP-2 group had fused by six months. However, early graft lucency and significant (> 10%) subsidence were seen radiologically in 27 of 55 levels in this group. The mean graft height subsidence was 27% (13% to 42%) for anterior lumbar interbody fusion, 24% (13% to 40%) for transforaminal lumbar interbody fusion, and 53% (40% to 58%) for anterior cervical discectomy and fusion. Those who had undergone fusion using allograft and demineralised bone matrix lost only a mean of 4.6% (0% to 15%) of their graft height. Although a high rate of fusion (100%) was achieved with rhBMP-2, significant subsidence occurred in more than half of the levels (23 of 37) in the lumbar spine and 33% (6 of 18) in the cervical spine. A 98% fusion rate (62 of 63 levels) was achieved without rhBMP-2 and without the associated graft subsidence. Consequently, we no longer use rhBMP-2 with allograft in our practice if the allograft has to provide significant structural support.

The effectiveness of orthopaedic trauma theatres in decreasing morbidity and mortality: a study of 701 displaced subcapital hip fractures in two trauma centres

In countries with universal health care systems patients frequently wait days for their "emergency" surgery. A general trend in orthopaedic traumatology is the advent of daily, dedicated orthopaedic trauma theatres. Availability of trauma theatres is believed to decrease morbidity and mortality, but this remains unproven. A retrospective review comparing morbidity and mortality outcomes between two similar level-one trauma centres (one without a dedicated trauma room system) was undertaken. We reviewed 701 elderly patients receiving hemiarthroplasties for displaced subcapital hip fractures over a 76-month period. Patients were similar between centres in terms of age, gender ratio and comorbidities. Statistically significant differences were found favouring the dedicated trauma room system with approximately half the operative delay and post-operative morbidity. A trend towards decreased mortality was also seen. This study supports the use of regular orthopaedic trauma theatres in tertiary care institutions.

Irrational drug use in India: a prescription survey from Goa

BACKGROUND

There is concern regarding the irrational production, prescription and use of drugs in India. This study aimed to describe the quality of prescriptions by medical practitioners, including both the layout of the prescription and the type and number of drugs prescribed.

MATERIALS AND METHODS

A survey of all prescriptions dispensed at a busy pharmacy in the state of Goa, India, was carried out over a consecutive seven-day period. Each prescription was rated on the basis of a priori and pilot-tested variable list. The prescriptions by private practitioners were compared with those from practitioners in the public healthcare system.

RESULTS

Nine hundred and ninety prescriptions were collected. The majority (83.9%) were from private practitioners. The quality of the layout of the prescriptions was unsatisfactory: information to identify the practitioner was incomplete in more than a third of the prescriptions and information to identify the patient was incomplete in more than half. Clarity of written instructions on how to take the medicines was unsatisfactory in the majority of prescriptions. Polypharmacy was the norm, with more than half (52.7%) the prescriptions containing at least 3 medicines. Forty per cent of prescriptions included a vitamin or tonic preparation and a quarter of the prescriptions included an antibiotic and an analgesic. Over 90% of prescriptions contained only branded medicines. Private practitioners prescribed significantly greater number of medicines and were more likely to prescribe vitamins and antibiotics, and branded medicines.

DISCUSSION

This study confirms that the quality of prescriptions, both in terms of layout and the content of the drugs prescribed, is inadequate. There is a need to standardize the format of prescriptions in India so that all essential information is included. There is a need to strengthen an independent mechanism for continuing professional development of practitioners to ensure that patients are always given evidence-based, cost-effective treatments.

Results of simultaneous open reduction and Salter innominate osteotomy for developmental dysplasia of the hip

OBJECTIVES

To assess the results of simultaneous open reduction and Salter Innominate Osteotomy for developmental dysplasia of the hip in our context where there is a tendency for these cases to present late without having undergone any treatment previously.

MATERIAL AND METHOD

We retrospectively reviewed the record files and radiographs of 22 dislocated hips of 20 patients managed with simultaneous open reduction and Salter osteotomy at Hospital and Rehabilitation Centre for Disabled Children from 1999 to 2001. Only eight patients with 9 hips with purely developmental dysplasia of hip aged one to seven years were included. The acetabular index on the initial and final radiographs was measured. The neck shaft angle was also measured. All radiographs were evaluated to determine the presence of avascular necrosis of the femoral head and position of the head after the operation. Clinical results were determined using modification of the McKay criteria (Pain, ROM, LLD, Containtment and Gait) . Follow-up ranged from a minimum of 1 year to a maximum of 5 years (average 3 years and 1 month).

RESULTS

The results were excellent in 7 hips (77.77%) good in 1 hip (11.11%) and poor in 1 hip (11.11%) according to modified McKay criteria.. No complications related to infection, graft fracture, vascular or neural injury were encountered.

CONCLUSION

When case selection for surgical treatment is appropriate, a reasonable excellent to good result can be expected even in cases such as ours which present late.

Serum leptin concentrations in hyperinsulinemia in the sets of obese, lipodystrophic and/or non-obese patients

OBJECTIVE

To study the relationship between serum leptin and circulating insulin under basal and in response to oral glucose administration in hyperinsulinemic patients with or without obesity.

MATERIAL AND METHOD

Fifteen female patients of known hyperinsulinemia provided material for the study. Leptin and insulin in sera were estimated by radioimmunoassay methods.

RESULTS

Eight of the 15 hyperinsulinemic patients with high body mass index (BMI) (31 +/- 0.94 kg/m2) had significantly (p < 0.01) elevated serum leptin concentrations (26.1 +/- 2 ng/ml) as compared to the levels in the remaining seven non-obese hyperinsulinemic patients with BMI of 20 +/- 1.0 kg/m2; their mean levels of serum leptin were low 5.7 +/- 1.1 ng/ml. Four of the latter group had face-sparing partial lipodystrophy. The mean circulating leptin concentrations in the control group of seven healthy normoinsulinemic and regularly menstruating women with normal BMI (19 +/- 0.95 kg/m2) were 13.7 +/- 1.8 ng/ml.

DISCUSSION

The results of the present study in 15 hyperinsulinemic patients show that circulating levels of leptin are not related to serum insulin. However, there was a positive correlation with BMI. An interesting observation of the study is that, notwithstanding the normal BMI, the group of hyperinsulinemic patients with face-sparing partial lipodystrophy had the lowest levels of circulating leptin concentrations. They were closer to the values found in prepubertal girls.

Computer-controlled laser ablation: a convenient and versatile tool for micropatterning biofunctional synthetic surfaces for applications in biosensing and tissue engineering

This paper describes laser-based methods for preparing micropatterns of bioactive molecular species in self-assembled monolayers (SAMs) and micropatterns of proteins and other biological molecules immobilized on solid substrates. Applications of these micropatterned surfaces in multianalyte biosensing and tissue engineering are emphasized. The focus of the paper is on the use of a computer-controlled laser ablation system comprising a research-grade inverted optical microscope, a pulsed nitrogen-pumped dye laser emitting at 390 nm, a programmable sample stage, and the computerized control system. The laser system can be implemented in a typical biosensor or tissue culture laboratory to enable the facile and reproducible fabrication of micropatterned surfaces by several methods. Various methods for patterning are discussed with examples given and emphasis placed on (1) laser ablation in the fabrication of photolithography masks, (2) electrochemical patterning of SAMs, and (3) laser desorption of SAMs. The relative merits of each technique are discussed with respect to application in fabrication of active surfaces for biosensing and tissue culture applications.

Spirometric changes after open mitral surgery

New York Heart Association (NYHA) functional classification of cardiac patients is assessed by subjective impairment of respiratory reserve. We objectively studied pulmonary function by spirometry in 31 random patients (average age 27.2 years) with rheumatic mitral valve (MV) disease undergoing open surgery (7 reconstruction, 24 replacement) preoperatively, predischarge and at 3 month follow-up. Better preoperative spirometric parameters were observed in class II nonsmoker patients with smaller cardiothoracic ratio (CTR) and normal pulmonary artery pressure (PAP). After surgery mean PAP decreased to 19.0 +/- 6.7 mmHg, MV gradient dropped to 3.4 +/- 2.9 mmHg, average CTR decreased to 52.3 /- 5.5%. MV area increased significantly from 0.8 +/= 0.49 to 2.45 +/- 1.23 cm2. Forced vital capacity (FVC), forced expiratory volume in one second FEV1), flow rates at 25%-75% of expired vital capacity (FEF 25-75%) and maximum voluntary ventilation (MVV) decreased significantly in all patients at discharge. Prolonged postoperative ventilatory support over 10 hours led to markedly reduced predischarge FVC, FEV1, FEF50, MVV and maximum mid expiratory flow rate (MMEFR). Prolonged cardiopulmonary bypass over 80 minutes caused further decrease in FVC. After 3 months all these parameters improved in all above the preoperative level but remained below the predicted values. Despite improvement in NYHA class, impaired spirometry was observed in 11 patients. Functional or hemodynamic improvement did not correlate with spirometric changes.

Effect of interference on the performance of glucose enzyme electrodes using Nafion coatings

The negatively charged perfluorinated ionomer Nafion was used as a coating on hydrogen peroxide detecting platinum electrode as well as on a polycarbonate diffusion membrane in the construction of a glucose amperometric enzyme electrode. The current response of these electrodes to hydrogen peroxide, ascorbic acid, acetaminophen, uric acid and glucose was studied and the coating procedure was optimized. It was confirmed that the Nafion coating prevents interference by anionic substances such as ascorbic acid and uric acid, and decreases acetaminophen interference. In this regard it was shown that coating the glucose diffusion membrane (polycarbonate) was more effective than coating the platinum wire itself, because of the prevention of the homogeneous redox reaction of the interference species with hydrogen peroxide, as well as the additional diffusional resistance to the glucose flux. The glucose levels in serum samples were estimated and the stability of the enzyme electrodes during continuous operation in serum was studied. An enzyme electrode with constant sensitivity of ca. 1 microA/mM and a linear range of up to 15 mM, unaffected by contact with serum, is reported.

Use of charged membranes to control interference by body chemicals in a glucose biosensor

The prerequisite for the continuous in vivo monitoring of glucose concentration is the development of an implantable glucose sensor with long-term stability. A new enzyme electrode concept featuring fluid-state glucose oxidase modified carbon powder along with a cross-linked glucose oxidase enzyme layer has been developed. The glucose sensor incorporating this enzyme electrode has been tested in vitro at 37 degrees C. It has a lifetime of three months after which it can be recharged with fresh enzyme. The next step in the characterization of this sensor is its in vitro behaviour in the presence of interfering substances commonly encountered in human blood. Here we report such a study of the sensor. The glucose diffusion membranes used were polycarbonate membranes. We used standard polycarbonate membranes (membranes treated with polyvinylpyrrolidone or PVP), PVP-free polycarbonate membranes, and standard polycarbonate membranes coated with positively and negatively charged hydrogel layers. The sensors showed a response to glucose concentrations < 300 mg dL-1, both in pure phosphate buffer and in the presence of interferences. The influence of ascorbic acid, bilirubin, creatinine, L-cystine, glycine, uric acid and urea on the amperometric signal of the sensor was investigated. The polycarbonate membrane coated with the negatively charged hydrogel layer provided good protection for the enzyme electrode, especially in the presence of ascorbic acid and uric acid.

Application of polytetrafluoroethylene (PTFE) membranes to control interference effects in a glucose biosensor

The implantable feedback-controlled insulin delivery system provides the greatest potential for the control of certain types of diabetes mellitus. The development of an implantable glucose sensor is thus a prerequisite. A glucose biosensor using the enzyme glucose oxidase immobilized on fine carbon powder has been developed. Its in-vitro behavior is investigated in the presence of interfering substances commonly encountered in human blood and other body fluids. Here, in-vitro interference tests carried out on this sensor with polytetrafluoroethylene (PTFE) membranes are described. The authors used PTFE membranes (pore size 0.02 micron), some of which were coated with positively and negatively charged hydrogel layers. The sensors showed a stable and linear response to glucose concentrations > 300 mg/dL, in the presence of glucose alone in the phosphate buffer medium and in the presence of interferences. The interference effects of ascorbic acid, bilirubin, creatinine, L-cystine, glycine, uric acid, and urea on the amperometric signal of the sensor were studied. The PTFE membrane coated with the negatively charged hydrogel layer provided good protection for the enzyme electrode, especially in the presence of ionic interferants such as ascorbic acid and uric acid.

Serum gonadotropins and testosterone in infertile patients with varicocele

Serum concentrations of gonadotropins and testosterone in 25 infertile men with varicocele were compared with those in control men and men with idiopathic oligo-azoospermia. No significant difference was found in values of serum follicle-stimulating hormone (FSH) (14.9 +/- 13.6 mIU/ml), luteinizing hormone (LH) (24.9 +/- 19.1 mIU/ml), and testosterone (5.0 +/- 2.1 ng/ml) when the group with varicocele was compared with either the control group (FSH, 7.0 +/- 3.2 mIU/ml; LH, 23.6 +/- 16.0 mIU/ml; testosterone, 5.3 +/- 1.8 ng/ml) or the group with idiopathic oligo-azoospermia (FSH, 23.0 +/- 22.69 mIU/ml; LH, 36.7 +/- 24.1 mIU/ml; testosterone, 5.31 +/- 2.3 ng/ml). However, compared with the control group, there was a significant elevation of serum FSH levels in patients with varicocele whose testicular biopsy score counts were between 1 and 4. The importance of preoperative determination of the serum FSH level is discussed.