Population pharmacokinetics of liposomal amphotericin B in adults with HIV-associated cryptococcal meningoencephalitis

BACKGROUND

Single, high-dose liposomal amphotericin B (LAmB; AmBisome, Gilead Sciences) has demonstrated non-inferiority to amphotericin B deoxycholate in combination with other antifungals for averting all-cause mortality from HIV-associated cryptococcal meningitis. There are limited data on the pharmacokinetics (PK) of AmBisome. The aim of this study was to describe population PK of AmBisome and conduct a meta-analysis of the available studies to suggest the optimal dosing for cryptococcal meningoencephalitis.

METHODS

Data from a Phase II and Phase III trial of high-dose, short-course AmBisome for cryptococcal meningoencephalitis were combined to develop a population PK model. A search was conducted for trials of AmBisome monotherapy and meta-analysis of clinical outcome data was performed.

RESULTS

A two-compartment model with first-order clearance of drug from the central compartment fitted the data best and enabled the extent of inter-individual variability in PK to be quantified. Mean (SD) population PK parameter estimates were: clearance 0.416 (0.363)  L/h; volume of distribution 4.566 (4.518) L; first-order transfer of drug from central to peripheral compartments 2.222 (3.351)  h-1, and from peripheral to central compartment 2.951 (4.070)  h-1. Data for the meta-analysis were insufficient to suggest optimal dosing of AmBisome for cryptococcal meningoencephalitis.

CONCLUSIONS

This study provides novel insight into the PK of AmBisome at the population level and the variability therein. Our analysis also serves to highlight the paucity of data available on the pharmacodynamics (PD) of AmBisome and underscores the importance of thorough and detailed PK/PD analysis in the development of novel antifungals, by demonstrating the challenges associated with post hoc PK/PD analysis.

The utility of the ISAC allergen array in the investigation of idiopathic anaphylaxis

A diagnosis of idiopathic anaphylaxis following a detailed clinical assessment remains very challenging for patients and clinicians. Risk reduction strategies such as allergen avoidance are not possible. This study investigated whether the (ISAC) allergen array with 103 allergens would add diagnostic value in patients with idiopathic anaphylaxis. We extended the specific immunoglobulin (Ig)E testing in 110 patients with a diagnosis of idiopathic anaphylaxis from five UK specialist centres using ISAC arrays. These were divided into three groups: score I identified no new allergen sensitization beyond those known by previous assessment, score II identified new sensitizations which were not thought likely to explain the anaphylaxis and score III identified new sensitizations felt to have a high likelihood of being responsible for the anaphylaxis. A proportion (50%) of score III patients underwent clinical reassessment to substantiate the link to anaphylaxis in this group. The results show that 20% of the arrays were classified as score III with a high likelihood of identifying the cause of the anaphylaxis. A wide range of major allergens were identified, the most frequent being omega-5-gliadin and shrimp, together accounting for 45% of the previously unrecognized sensitizations. The ISAC array contributed to the diagnosis in 20% of patients with idiopathic anaphylaxis. It may offer additional information where a careful allergy history and follow-on testing have not revealed the cause of the anaphylaxis.

Recognition of physical deterioration in patients with mental health problems: the role of simulation in knowledge and skill development

Recognition of physical deterioration in patients with mental health problems has been recognized as a significant problem. Areas of particular concern include rapid tranquilization, physical restraint, the consumption of alcohol and illicit drugs have the potential to result in sudden and catastrophic patient deterioration. Simulation sessions, using patient mannequins, are widely used to support the education of nurses but its use in mental health has been somewhat restricted. The aim of this study was to design and deliver simulation scenarios to develop the skills and knowledge of mental health nursing students in the recognition and management of physical deterioration. A series of three scenarios were developed and delivered to a group of final-year nursing students. Evaluation of the sessions was undertaken using analysis of video footage from the sessions and through two focus groups. The results show that simulation is a useful catalyst for discrepancy creation which in turn leads to the student focusing their future learning towards addressing any identified deficits in skills and knowledge identified. Authenticity of the simulation sessions also plays a role in ensuring student engagement and faculty support during sessions is vital to support the students in managing unfamiliar situations.

Pulsed low intensity ultrasound enhances mineralisation in preosteoblast cells

Pulsed low intensity ultrasound has been shown to be highly efficacious in the treatment of nonunion fractures and in the acceleration of fresh fracture healing. MC3T3-E1 subclone 14 cells were cultured for up to 25 days either with or without a daily treatment with low intensity pulsed ultrasound. It was determined that, on day 10 there was a dramatic increase in alkaline phosphatase and MMP-13 mRNA levels detected in ultrasound-treated cultures compared with untreated controls. The activity of alkaline phosphatase was significantly increased at days 6, 8 and 10. On day 10, the amount of mineralisation within cultures, assessed using alizarin red staining, was significantly increased in ultrasound-treated cultures compared with untreated controls. These results suggest that one of the mechanisms that low intensity pulsed ultrasound has on fracture repair is to enhance the process of endochondral ossification where the soft callus is converted to mineralised hard callus.

Engaging women from South Asian communities in cardiac rehabilitation

This study sought to describe experiences and perceptions of cardiac rehabilitation among a sample of women from South Asian communities. Data were collected via eight semi-structured interviews with staff and a focus group discussion with nine clients from a community-based, culturally sensitive cardiac rehabilitation service. A number of individual, cultural and practical barriers to participation were identified. Facilitators centred on whether the format and content of the sessions could be considered "appropriate". For example, a women's dance group proved to be successful through the selection of a familiar local venue, supportive session leader, and activity that was felt to be both enjoyable and beneficial. This study has shown that it is possible to engage hard-to-reach groups in cardiac rehabilitation and physical activity. Further work is needed to explore whether this research is applicable in other ethnic groups and whether the lessons learned could be successfully incorporated into mainstream health services.

Controlled degradation and macrophage responses of a fluoride-treated polycaprolactone

We have developed a new bone replacement material based on polycaprolactone (PCL), which can act as a suitable matrix for monomer transfer molding of degradable composites. A boron trifluoride catalyst with glycerol additive was used to produce PCL with a degradation rate that can be altered by treatment with fluoride ions. The effect of cations on the degradation of the polymer and macrophage cell responses are discussed. We found that treatment with fluoride ions reduced the degradation rate. No significant difference between these three fluorides was observed although a general trend was seen where KF-treated PCL appeared to degrade slower than NaF-treated PCL which was slower than NH(4)F-treated PCL. Variation in solubilities of the salts was observed where the K(+) cation had the highest solubility and the Na(+) cation had the lowest solubility, which suggests that NaF was able to degrade the polymer more efficiently than the other fluorides. No significant macrophage activation was observed after culture on the polymer surfaces as determined by peroxide and IL-1 beta release, whereas some activation occurred after culture in degradation products.

Removal of dioxins and related aromatic hydrocarbons from flue gas streams by adsorption and catalytic destruction

The dioxin removing capacity of the shell dedioxin system (SDDS-a Ti/V oxidative type catalyst) has been tested using the Umeå lab-scale incinerator over the temperature range 100-230 degrees C and at space velocities of 8000 and 40,000 h(-1). Other analogous organic compounds, such as PCBs, PAHs, chlorobenzenes and chlorophenols have also been investigated. Results show a high degree of dioxin removal already at 100 degrees C (82%), which occurs mainly by adsorption. When the temperature is raised a transition towards destruction is seen and at 150 degrees C, gas hour space velocity (GHSV) 8000 and at 230 degrees C, GHSV 40,000 virtually all removal is by destruction. High PCDD/F destruction efficiencies are reported (> 99.9%, based on I-TEQ); the other dioxin-related species and PAHs are also removed and destroyed to a significant extent. The SDDS has proved to be an effective means of destroying organic compounds in the gas phase, particularly dioxins, at temperatures as low as 150 degrees C.

Management of bladder problems in patients with multiple sclerosis

Bladder problems are a common feature in patients with multiple sclerosis (MS). Many patients experience distressing symptoms such as frequency, urgency and incontinence, unaware of the range of treatments which are available to either overcome or manage their bladder problems. While patients with MS may experience many types of bladder dysfunction, certain types of problem are more common in this patient group. These problems can be grouped under the headings of storage, emptying or combined dysfunction. Community nurses are well-placed to offer methods of containment by providing first-line treatment as well as identifying which patients need to be referred to other members of the multidisciplinary team.

Access all areas: wound care resources on the Internet

The World Wide Web provides access to a plethora of information on every conceivable topic. More and more, the Internet is been used to access health information, making service users better informed about their conditions and the choice of treatment. It is essential that healthcare professionals embrace this technology so that they are able to access information from around the world. Ideally, access to such technology should be as close as possible to the point of care delivery. The expansion of the NHSnet over the next 3-5 years should make this a reality for more and more practitioners.

An evaluation of current risk assessment scales for decubitus ulcer in general inpatients and wheelchair users

OBJECTIVES

To study the components of two risk assessment scales for decubitus ulcer risk, Waterlow and Braden, and of the Chailey score for the same purpose.

DESIGN

Experimental study of patients at risk of developing decubitus ulcers.

SETTING

The West Midlands and Yorkshire.

SUBJECTS

One hundred and fifty wheelchair users from the West Midlands and 9022 patients from a District General Hospital in York, the latter consisting of all admissions to the hospital in a four-month period.

INTERVENTIONS

Braden, Chailey scores (wheelchair users) and Waterlow scores (all subjects) measured.

MAIN OUTCOME MEASURES

Development of a pressure sore, receiver operating characteristic (ROC) curves.

RESULTS

Waterlow outperformed Braden for classification of wheelchair patients with respect to decubitus ulcer. The Chailey score performed randomly in this group. The sensitivity and specificity as seen in ROC curves was different for Waterlow scores for wheelchair users and general patients, the latter being much better classified. Only three items out of 11 in the Waterlow score appeared to have any classification ability in the wheelchair group.

CONCLUSIONS

Risk indicators used for general patients are probably poorly suited for wheelchair users. There is a need for large-scale predictive studies of wheelchair users and other groups to allow regression analysis of the subscales of risk indicators. From the provisional data of this study it appears that splitting patients by gender and into full- and part-time wheelchair users classifies almost as well the much more complicated risk assessment tools currently available.

Systemic lupus erythematosus presenting as congenital nephrotic syndrome

A male Caucasian infant developed nephrotic syndrome at 10 weeks of age. He had high titres of antinuclear antibody (ANA) and anti-double-stranded DNA antibody, with hypocomplementaemia, antiplatelet antibodies and anticardiolipin antibodies. There were no detectable antibodies to extractable nuclear antigens (ENA). His mother was consistently seronegative for anti-ENA (anti-Ro) antibodies and ANA. He developed severe, progressive multisystem involvement, however renal function has remained stable. Immunosuppression has been the mainstay of therapy in this rare presentation of systemic lupus erythematosus.

Stress incontinence: treatment using pelvic floor re-education

Stress incontinence is the most common cause of urinary incontinence. A pelvic floor assessment is an essential prerequisite to all pelvic floor exercise programmes. Many patients with stress incontinence can be cured using a programme of exercises. The use of weighed pelvic floor cones with an exercise programme increases compliance and enables patients to perform resisted exercises in their own homes.

Patient satisfaction: an indicator of quality in disablement services centres

OBJECTIVES

To develop a patient satisfaction system for disablement services centres and to report on how the initial findings have been used in audit to improve their quality of care and services.

DESIGN

Interview survey of randomly selected users attending in three centres: Birmingham (centre X), Oxford (centre Y), and Cambridge (centre Z) to establish core topics for developing a patient satisfaction questionnaire with incorporation into a computer patient satisfaction system (PATSAT) to enable collation of responses to the questionnaire. A pilot of the questionnaire was undertaken in the centres to assess the sensitivity of the questionnaire, which was subsequently used as part of clinical audit process during June 1991 and April 1992 in centre X and the patient satisfaction system used to monitor changes in routine practice.

PATIENTS

123 amputees in the development phase, selected by cluster sampling, and 1103 amputees in the pilot study.

MAIN MEASURES

Satisfaction scores for components of the service.

RESULTS

The questionnaire included 16 core topics contributing to quality of care and services, including comfort of limbs, appointments, interpersonal aspects of care, a system of support and counselling, and organisation. The pilot survey demonstrated high satisfaction scores for aspects of interpersonal care, organisation, and physical surroundings of the centres and lower satisfaction for counselling services, comfort of the limb and the number of alterations made before the limb was considered acceptable. During the audit in centre X these results prompted changes to care and services which produced significant improvements in satisfaction.

CONCLUSIONS

The early results suggest that the questionnaire, coupled with PATSAT software system, enable users' views to be expressed, collated, and fed back to staff; the information provided has already prompted change, and the system is sufficiently sensitive to measure changes in satisfaction with the service.

Containing incontinence in men: an extra dimension

The prevalence and nature of incontinence means that all nurses will see patients who suffer from this condition. Many professionals remain unaware of products that can assist in the management of such patients. This article describes experience with some of the products available, highlighting their clinical usefulness and effectiveness.

Hypoxic-reperfusion injury in the inflamed human joint

A series of experiments showed that, on exercise of the inflamed human knee, intra-articular pressure rises above synovial capillary perfusion pressure, causing intra-articular hypoxia; and that, on cessation of exercise, there is oxidative damage to lipids and IgG within the joint. These findings are consistent with the hypothesis that persistence of synovial inflammation can be due to exercise-induced hypoxic-reperfusion injury mediated by reactive oxygen species.

Simple model for piezoelectric ceramic/polymer 1-3 composites used in ultrasonic transducer applications

A theoretical model is presented for combining parameters of 1-3 ultrasonic composite materials in order to predict ultrasonic characteristics such as velocity, acoustic impedance, electromechanical coupling factor, and piezoelectric coefficients. Hence, the model allows the estimation of resonance frequencies of 1-3 composite transducers. This model has been extended to cover more material parameters, and they are compared to experimental results up to PZT volume fraction nu of 0.8. The model covers calculation of piezoelectric charge constants d(33) and d(31). Values are found to be in good agreement with experimental results obtained for PZT 7A/Araldite D 1-3 composites. The acoustic velocity, acoustic impedance, and electromechanical coupling factor are predicted and found to be close to the values determined experimentally.

The role of calcium ions in the activation of rabbit psoas muscle

This study tested the effects of free Ca++ on both the small-amplitude mechanical behaviour (dynamic stiffness and phase between 1 and 500 Hz) and the large-scale filament-sliding behaviour (Vmax) of single fibres of chemically-activated glycerol-extracted rabbit psoas muscle. Small-amplitude vibrations (0.1% peak-to-peak of initial length L0) were used to elicit fw, the frequency for maximum oscillatory work-production per cycle. The unloaded contraction velocity Vmax was measured during the same contractions, using the slack-test method with shortening length steps of up to 10% L0. These produced nonlinear length-time plots demonstrating that the unloaded contraction velocity was not constant as contraction progressed, but fell with time. This behaviour was approximated by two velocities, V1 the velocity observed for about the first 15 ms and V2 the velocity after this time. V1 and V2 were found to have different sensitivities to Ca++. The value of V2 fell as the level of [Ca++] was reduced, and was linearly proportional to the active tension over the range 0.2 Pmax to Pmax (where Pmax is the isometric tension for saturating amounts of Ca++). In contrast to this V1 remained insensitive to changes in [Ca++] for levels of activation corresponding to active tensions ranging from Pmax to 0.6 Pmax, and then fell as the level of activation was further reduced. It was found that the level of [Ca++] did not affect the magnitude of fw over the range of concentrations yielding active tensions from 0.2 Pmax to Pmax. These results are discussed in terms of the kinetic processes underlying transient readjustments to perturbations from isometric equilibrium.

Serum salicylate levels in a breast fed infant

All drugs should be given with caution to pregnant or breast feeding women. Recent concern about the role of salicylates in the aetiology of Reye's syndrome has prompted the DHSS to restrict the use of aspirin in children. The case of a 9 week old breast fed infant whose serum contained 0.47 mmol/l of salicylate is reported. Her mother was taking aspirin 2.4 g/day, and it is concluded that salicylates must not be taken by breast feeding mothers.

Renal impairment associated with non-steroidal anti-inflammatory drugs

We have compared the renal function on admission and discharge of 22 patients routinely admitted to our rheumatology ward. None had previously diagnosed renal failure. Of 11 patients in whom we stopped long term non-steroidal anti-inflammatory drug (NSAID) therapy, all showed a rise in creatinine clearance (Ccr) after three to 28 days. In contrast, a control group comprising 11 similar patients who continued to receive NSAIDs showed no significant change. Recent work has suggested that it is possible to identify patients at risk of developing nephrotoxic side effects with NSAIDs. Based on these criteria (but excluding age alone as a risk), six patients from the first group and 10 from the second group would have been without risk. We infer from this that asymptomatic, reversible impairment of renal function is common, and that the potential clinical benefit from the use of NSAIDs should be balanced against this predictable toxicity.

Protracted diarrhoea of infancy: evidence in support of an autoimmune variant

Circulating autoantibodies to enterocytes were detected by indirect immunofluorescence in 14 out of 25 patients with idiopathic protracted diarrhoea of infancy. Similar specificities were not found in 50 control children with nongastroenterological disorders. The immunofluorescence pattern was more accentuated on the apical border of mature enterocytes. Enterocyte autoantibodies were mainly of IgG class (13/14), but 11 sera were positive for IgM and IgA classes, and five out of 14 positive sera also had the ability to fix complement. Absorption of sera positive for autoantibodies with an IgA coupled immunoabsorbent did not modify the intensity of the staining, indicating that these antibodies were not directed against secretory IgA. High titres and the complement fixing ability of enterocyte autoantibodies indicated a poorer prognosis despite the use of immunosuppressive drugs. Organ specific and non-organ specific autoimmune diseases or corresponding autoantibodies or both were often found in children with enterocyte autoantibodies and their family. These data show the existence of an autoimmune variant of protracted diarrhoea of infancy, despite the rare occurrence of autoimmune diseases in childhood.

Enalapril in the treatment of hypertension associated with impaired renal function

This pilot study was undertaken to examine the safety and efficacy of enalapril in the treatment of hypertension associated with impaired renal function. Forty-one patients with glomerular filtration rate (GFR) < or = 50 ml/min received enalapril for up 12 weeks. Blood pressure, renal function, biochemistry and haematology were monitored weekly for 4 weeks and then monthly. Blood pressure was effectively reduced within 4 weeks; this reduction was maintained for at least 12 weeks. Renal function remained stable and there was no significant sustained alteration in any biochemical or haematological parameter. Requirement for additional antihypertensive drugs was reduced during enalapril therapy. These data suggest that enalapril may have a useful role in the management of hypertension associated with renal impairment.

The use of single photon emission computed tomography in lung imaging with aerosols

The use of technetium-99m labelled diethylenetriaminopentaacetic acid (99Tcm-DTPA) aerosol and single photon emission computed tomography (SPECT) to obtain sectional ventilation images of the lung is demonstrated in a limited series of patients. SPECT perfusion and planar ventilation and perfusion are also obtained and the SPECT studies compared with the planar views to assess the efficacy of SPECT aerosol ventilation images when used in conjunction with SPECT perfusion studies. The problems encountered in SPECT aerosol lung imaging, particularly the image noise associated with the limited number of detected counts, are described. On the basis of the results it is concluded that the technique is worth further assessment.

Fatal unresponsive villous atrophy of the jejunum, connective tissue disease and diabetes in a girl with intestinal epithelial cell antibody

The patient presented with a diabetes at the age of 3 years. At the age of 5 years she got persistent diarrhoea, lost weight and showed symptoms or arthritis and pericarditis. She was found to have total villous atrophy of the jejunum, which did not respond to dietary treatment, total parental nutrition, prednisone and cyclophosphamide medication. She had high titres of antinuclear antibodies and elevated serum IgG, but antibodies to DNA and to ribonuclearprotein were negative. A low titre of antibodies to human intestinal epithelial cells was found. The patient died of overwhelming fungal sepsis. We propose that the intestinal damage is part of the autoimmune disease. Careful study of jejunal biopsy specimens is helpful in distinguishing this type of patient from patients with coeliac disease.

Flat small intestinal mucosa and autoantibodies against the gut epithelium

A male infant, aged 1 year 3 months, was admitted to the hospital with protracted diarrhoea, vomiting, and weight loss. The diarrhoea and vomiting coincided with an outbreak of acute diarrhoea and vomiting affecting other family members. Biopsy showed a flat small intestinal mucosa which did not respond to a diet free of gluten, cow's milk, and eggs, or during 8 weeks of intravenous alimentation. Steroids were given, and courses of nalcrom and later cimetidine, but these did not produce any significant improvement. A rare IgG autoantibody specific for gut epithelium was found, which, when present, was associated with a cytological abnormality of crypt enteroblasts. The autoantibody disappeared after treatment with cyclophosphamide, and the cytological abnormality subsequently diminished. However, the mucosa remained severely abnormal and has been so for 23 months. It is possible that an autoimmune reaction against the patient's small intestinal mucosa has led to persistence of the enteropathy.

The initial investigation of jaundice in a district general hospital: a study of ultrasonography and hepatobiliary scintigraphy

Twenty-five jaundiced patients presenting to a district general hospital were investigated by both ultrasonography (performed by a medical physicist) and hepatobiliary scintigraphy using 99Tcm-HIDA. Hepatobiliary scintigraphy was completely unable to distinguish medical from surgical jaundice. However, with mild jaundice--bilirubin < 100 mumol/l--the presence or absence of gall-bladder activity fairly accurately predicted the presence or absence of gall-bladder disease. Ultrasonography had three technical failures. Of the remaining 22 patients, medical jaundice was correctly predicted in nine of ten patients and surgical jaundice in eight of 12 patients. Erroneous results were only obtained from patients with mild jaundice, the accuracy being 100% in the 15 patients with serum bilirubin > 60 mumol/l. In a district general hospital ultrasonography is recommended as the investigation of first choice in jaundice, perhaps complemented by hepatobiliary scintigraphy when the jaundice is mild.

Frequency-domain study of the mechanical response of living striated muscle

Small-amplitude sinusoidal displacements, in the frequency range 4-100 Hz, were applied to intact whole frog sartorius muscle whilst in a state of tetanus. At low frequencies the muscle was observed to do oscillatory work, while at higher frequencies it tended towards elastic behaviour. Frequency-response plots obtained were compared with those from other muscle preparations. Results were interpreted in terms of mechano-chemical transduction properties of muscle.