How is the indoor environment related to asthma?: literature review

AIMS

This paper reports a review conducted to identify the factors in the indoor environment that have an evidence-based link with the exacerbation or development of asthma and to identify measures that healthcare professionals can promote to reduce exposure to these risk factors in the home.

BACKGROUND

The indoor environment, particularly at home, has been recognized as a major source of exposure to allergens and toxic chemicals. Exposure to allergens and toxins is thought to exacerbate respiratory conditions, in particular, asthma.

METHODS

Searches were made of health and indoor environment databases, including Cochrane Library, National Health Services Centre for Reviews and Assessment Reports, British Medical Journal, CINAHL and Ovid library, MEDSCAPE/MEDLINE, EMBASE, INGENTA, Science Citation Index, Web of Science. Searches were also made of other Internet-based resources, including those of international and government bodies. The following keywords were used: allergens, allergen avoidance, asthma, asthma prevention, cat, damp, Der p 1, dog, environmental control, house dust mites, indoor air quality, indoor environment, meta analysis, mould, pets, remedial actions, respiratory illnesses and systematic reviews.

FINDINGS

There is evidence of a link between asthma and a small number of indoor environmental factors. There is currently only reasonable evidence for one causative factor for asthma in the indoor environment and that is house dust mite allergen. Although there are many studies of different remedial actions that can be taken in the home, often these give evidence of reduced risk of exposure but not clinical improvement in asthma. Although there is a lack of medical evidence for the reduction of known sensitizers such as mould, this is because of a dearth of research rather than evidence of no association.

CONCLUSIONS

There is some evidence of a link between the indoor environment and asthma. There are measures, which could be promoted by healthcare professionals to alleviate asthmatic symptoms.

How can I quit passive smoking?

Passive smoking is a topical subject and there is a concerted movement to increase public understanding of the dangers of passive smoking. Although it looks likely that smoking could be banned in public places in the UK by the year 2008, it will still be difficult to enforce smoking bans in the last bastion for the smokers--their homes. Many smokers are aware of the risk their smoking causes their families through passive smoking but do not realise that the only true method for them to reduce exposure for their family is to smoke outside the home. This is partly because of a lack of understanding of the behaviour of environmental tobacco smoke and how smoking in restricted areas alone will not eliminate passive smoking for other family members in their homes.

Cold agglutinin related acrocyanosis and paroxysmal haemolysis

The clinical features of severe cold agglutinin related paroxysmal agglutination and haemolysis could be confused with a number of conditions. A 61-year old lady presented with features of acute peripheral ischaemia who had recently been started on treatment for Raynaud's disease. Haematological investigations revealed the presence of potent cold haemagglutinins to be the cause of her symptoms but no definite cause for the raised titres were found. She was managed conservatively by keeping her hands and feet warm and regular chlorambucil for a suspected underlying lymphoproliferative disorder. It is important to differentiate the features of Raynaud's disease from those of severe haemagglutination so that identification of any underlying disorder can be made and appropriate treatment instituted.

Enhancing patient-based learning: introducing STRAC and the reflective history template

The University of New South Wales School of Rural Health, Australia, like many other rural clinical schools, relies heavily on patient-based learning which is largely serendipitous. The learning is not driven by courses of lectures but by the patients who become available in a variety of settings. Students, who, in their first 3 years have been exposed to a very structured didactic learning experience, start their rural experience in Year IV with a curriculum mainly concerned with general medicine and surgery. They have to learn to adapt to a largely self-directed model. While their rural clinical experience is very much broader than that of their city-based peers, an excellent feature, it engenders feelings of insecurity and a perceived need for students and faculty to have a method of tracking patient encounters so they can ensure the syllabus is covered. Early attempts with a paper-based system and later a Reflective Learning Diary proved unsuccessful. This article presents Syllabus Tracking (STRAC) together with a Reflective Case History Template which encourages reflective learning from patients encountered. STRAC is a web-based solution that includes a reporting function, and is easily modified to suit the needs of the curriculum. It is believed it may also prove useful for future applications. Most rural clinical schools in Australia are young, as are these tools. They are not formally evaluated but are offered to other schools as a suggestion.

A randomised controlled trial to assess the effectiveness and cost of a patient orientated self management approach to chronic inflammatory bowel disease

OBJECTIVES

We developed a patient centred approach to chronic disease self management by providing information designed to promote patient choice. We then conducted a randomised controlled trial of the approach in inflammatory bowel disease (IBD) to assess whether it could alter clinical outcome and affect health service use.

DESIGN

A multicentre cluster randomised controlled trial.

SETTING

The trial was conducted in the outpatient departments of 19 hospitals with randomisation by treatment centre, 10 control sites, and nine intervention sites. For patients at intervention sites, an individual self management plan was negotiated and written information provided.

PARTICIPANTS

A total of 700 patients with established inflammatory bowel disease were recruited.

MAIN OUTCOME MEASURES

Main outcome measures recorded at one year were: quality of life, health service resource use, and patient satisfaction. Secondary outcomes included measures of enablement-confidence to cope with the condition.

RESULTS

One year following the intervention, self managing patients had made fewer hospital visits (difference -1.04 (95% confidence interval (CI) -1.43 to -0.65); p<0.001) without increase in the number of primary care visits, and quality of life was maintained without evidence of anxiety about the programme. The two groups were similar with respect to satisfaction with consultations. Immediately after the initial consultation, those who had undergone self management training reported greater confidence in being able to cope with their condition (difference 0.90 (95% CI 0.12-1.68); p<0.03).

CONCLUSIONS

Adoption of this approach for the management of chronic disease such as IBD in the NHS and other managed health care organisations would considerably reduce health provision costs and benefit disease control.

Supplementation of a home-based exercise programme with a class-based programme for people with osteoarthritis of the knees: a randomised controlled trial and health economic analysis

OBJECTIVES

To establish the relative effectiveness and cost of providing a home-based exercise programme versus home-based exercise supplemented with an 8-week class-based exercise programme.

DESIGN

The trial was a pragmatic, single-blind randomised clinical trial accompanied by a full economic evaluation.

SETTING

Patients were randomly allocated to either home-based exercise or home exercise supplemented with class exercise programmes.

PARTICIPANTS

A total of 214 patients, meeting the American College of Rheumatology's classification of knee osteoarthritis, were selected from referrals from the primary and secondary care settings.

INTERVENTIONS

Both groups were given a home exercise programme aimed at increasing lower limb strength, and endurance, and improving balance. The supplemented group also attended 8 weeks of twice-weekly knee classes run by a physiotherapist. Classes represented typical knee class provision in the UK.

MAIN OUTCOME MEASURES

Assessments of locomotor function, using a timed score of three locomotor activities, walking pain and self-reported disability with the Western Ontario and McMaster's Universities osteoarthritis index (WOMAC) were made. General health, lower limb strength, range of movement and compliance with exercise were also measured. Patients were assessed before and after treatment, and also at 6- and 12-month follow-ups. The economic evaluation looked at health service resource use and assessed cost-effectiveness by relating differential costs to differences in quality-adjusted life-years (QALYs) based on patients' responses to the EuroQol-5 Dimensions. Data were obtained at baseline, 1 month, 6 months and 12 months through face-to-face interviews and, where appropriate, examination of hospital medical records.

RESULTS

Patients from the supplemented group demonstrated significantly greater improvement in locomotor function and decrease in pain while walking at all follow-ups. The supplemented group also demonstrated smaller but significant improvements in balance, strength, WOMAC score, and the physical function and pain dimensions of the Short Form-36. However, not all of these improvements were maintained over the 12-month follow-up period. There was no evidence that compliance with the home exercise programme was different or that total costs or mean QALY gains were significantly different between the groups. However, costs were slightly lower and QALY gains slightly higher in the group with the supplementary class-based programme. The economic evaluation suggests that supplemented programmes are likely to be considered cost-effective, although there is uncertainty around this estimate, with approximately 30--35% probability that the intervention would not be cost-effective.

CONCLUSIONS

The supplementation of a home-based exercise programme with a class-based exercise programme led to superior improvement in the supplemented group. These differential improvements were still evident at review 12 months after treatment had ceased. The additional cost of the supplemented group was offset by reductions in resource use elsewhere in the system. Compliance with the home exercise programme did not differ between the groups. Based on this evidence, the supplementation of a home-based exercise programme with an 8-week class-based exercise programme can be confidently expected to produce small improvements in locomotor function and clinically important reductions in pain. It is recommended that future research investigates methods of increasing compliance with home exercise programmes and evaluates the impact of these interventions in the primary care setting, where most patients with knee osteoarthritis are managed.

Systematic review of the clinical effectiveness and cost-effectiveness of capecitabine (Xeloda) for locally advanced and/or metastatic breast cancer

OBJECTIVE

To examine the clinical effectiveness and cost-effectiveness of oral capecitabine for locally advanced and metastatic breast cancer in relation to its licensed indications.

DATA SOURCES

Twenty-three electronic databases and other databases of ongoing research and Internet resources, bibliographies of retrieved articles and industry submissions.

REVIEW METHODS

Two reviewers independently screened and assessed all titles and/or abstracts including economic evaluations. Randomised controlled trials (RCTs) and observational studies that investigated capecitabine monotherapy, in patients pretreated with an anthracycline-containing regimen or a taxane, or capecitabine in combination with docetaxel, in patients pretreated with an anthracycline-containing regimen, were included. The economic evaluation was based on data reported in the manufacturer's submission.

RESULTS

For capecitabine monotherapy, 12 uncontrolled observational studies were identified. The methodological quality of the studies was low. Capecitabine demonstrated antitumour activity, but was associated with a particular risk of hand-foot syndrome and diarrhoea. Economic evaluation was hampered by the poor quality of the published studies, but compared indirectly with vinorelbine, capecitabine was associated with lower costs and improved patient outcomes. For capecitabine in combination with docetaxel, one RCT was identified. Combination therapy was superior to single-agent docetaxel in terms of survival, time to disease progression and overall response. Adverse events occurred more frequently with combination therapy. The economic evaluation demonstrated an overall improved QALY score for combination therapy with a slight reduction in costs.

CONCLUSIONS

No conclusions could be drawn regarding the therapeutic benefit of capecitabine monotherapy; RCTs are required. Capecitabine appeared cost-effective compared with vinorelbine, but serious doubts remain; the poor quality of the trials may invalidate this conclusion. Based on limited evidence, combination therapy was more effective than single-agent docetaxel and likely to be cost-effective, but was associated with higher incidences of hand-foot syndrome, nausea, diarrhoea and stomatitis.

Bisphosphonate infusions: patient preference, safety and clinic use

GOALS OF WORK

We set out to assess the preference of patients with common cancers involving bone receiving intravenous bisphosphonate therapy for either pamidronate (P) or zoledronic acid (Z) and their preference for the location of the infusion (clinic or home). We also aimed to monitor these patients' renal safety, and to compare their time in clinic to receive P and Z infusions.

PATIENTS AND METHODS

Enrolled in the study were 184 patients, and all received initial infusions of Z (so any first infusion reactions did not confound preferences for P). For their second and third infusions, patients were randomized to receive Z then P or P then Z, and questioned on their preferences. For up to 1 year they continued on Z infusions every 3-4 weeks, while their renal safety was monitored. Where practical, later infusions were given at home (rather than in the clinic) and patients questioned on their preferred infusion location. In a convenience subset of 43 patients, clinic use for Z and P infusions was also measured by timing infusions and other procedures.

MAIN RESULTS

Of 144 patients who received a third infusion, 138 responded to questions on bisphosphonate preference, and of these 138, 92% (127) preferred Z to P, because shorter infusions caused less disruption to their day. Only 12% of eligible patients (16/138) received home infusions, but 13/14 questioned preferred this location. Among 184 patients, 19 episodes of renal impairment were noted, mostly owing to disease progression (e.g. obstructive uropathy), with none linked to Z therapy. The mean clinic time taken to receive Z and any concomitant therapy was about half that for P (78 vs 161 min).

CONCLUSIONS

Cancer patients prefer shorter bisphosphonate infusions-and at home, where practical. Regular Z 4 mg infusions appear to be safe in these patients, with routine monitoring of serum creatinine. Using Z rather than P could save busy cancer centres time and improve patient satisfaction.

A randomised controlled trial to assess the impact of a package comprising a patient-orientated, evidence-based self-help guidebook and patient-centred consultations on disease management and satisfaction in inflammatory bowel disease

OBJECTIVES

To determine if a whole systems approach to self-management improves clinical outcomes and leads to cost-effective use of NHS services.

DESIGN

Nineteen hospitals were randomised to 10 control sites and nine intervention sites. Consultants from intervention sites received training in patient-centred care before recruitment and introduced the intervention to eligible patients. Patients at the control sites were recruited and went on to have an ordinary consultation. Qualitative interviews were undertaken to obtain an in-depth understanding of patients' and consultants' experience of the intervention.

SETTING

Follow-up outpatient clinics at 19 hospitals in the north-west of England.

PARTICIPANTS

Seven hundred patients (297 at intervention sites and 403 at control sites) with established ulcerative colitis or Crohn's disease, aged 16 years and over, and able to write in English.

INTERVENTIONS

Consultants were trained to provide a patient-centred approach to care. Guidebooks on ulcerative colitis and Crohn's disease were developed with patients prior to the study. Patients prepared a written self-management plan and self-referred to services based on a self-evaluation of their need for advice.

MAIN OUTCOME MEASURES

Rates of hospital outpatient consultation, quality of life (QoL) and acceptability to patients. Health service resource use and assessed cost effectiveness using the EQ-5D.

RESULTS

After 1 year, the intervention resulted in fewer hospital visits, without change in the number of primary care visits. Patients felt more able to cope with their condition. The intervention produced no reduction in QoL and did not raise anxiety. The intervention group reported fewer symptom relapses; 74% of patients in the intervention group indicated a preference to continue the system. Qualitative results showed the guidebook was effective but organisational limitations constrained patient-centred aspects of the intervention for some. Cost-effectiveness analyses favoured self-management over standard care.

CONCLUSIONS

Further use of this method in chronic disease management seems likely to improve overall patient satisfaction and reduce health expenditure without evidence of adverse effect on disease control. Further attention needs to be given to self-referral and access arrangements and a re-distribution of control to patients through increased adherence to patient-centred norms on the part of consultants. Future research is recommended to evaluate the operating systems within secondary and primary care that would allow self-managers to self-refer and to keep them informed of new treatments, also to explore models for training health professionals in self-care methods, to study long-term effects of self-management in chronic disease and to transfer this approach to other chronic conditions.

Chronic corticosterone affects brain weight, and mitochondrial, but not glial volume fraction in hippocampal area CA3

Corticosterone (CORT), the predominant glucocorticoid in rodents, is known to damage hippocampal area CA3. Here we investigate how that damage is represented at the cellular and ultrastructural level of analyses. Rats were injected with CORT (26.8 mg/kg, s.c.) or vehicle for 56 days. Cell counts were estimated with the physical disector method. Glial and mitochondrial volume fractions were obtained from electron micrographs. The effectiveness of the CORT dose used was demonstrated in two ways. First, CORT significantly inhibited body weight gain relative to vehicles. Second, CORT significantly reduced adrenal gland, heart and gastrocnemius muscle weight. Both the adrenal and gastrocnemius muscle weight to body weight ratios were also significantly reduced. Although absolute brain weight was reduced, the brain to body weight ratio was higher in the CORT group relative to vehicles, suggesting that the brain is more resistant to the effects of CORT than many peripheral organs and muscles. Consistent with that interpretation, CORT did not alter CA3 cell density, cell layer volume, or apical dendritic neuropil volume. Likewise, CORT did not significantly alter glial volume fraction, but did reduce mitochondrial volume fraction. These findings highlight the need for ultrastructural analyses in addition to cellular level analyses before conclusions can be drawn about the damaging effects of prolonged CORT elevations. The relative reduction in mitochondria may indicate a reduction in bioenergetic capacity that, in turn, could render CA3 vulnerable to metabolic challenges.

Phase I/II study of concurrent twice-weekly paclitaxel and weekly cisplatin with radiation therapy for stage III non-small cell lung cancer

The optimal chemoradiation regimen for stage III non-small cell lung cancer (NSCLC) has not been determined. In this phase I/II study, the use of twice-weekly paclitaxel concomitant with weekly cisplatin and thoracic radiotherapy (RT) was evaluated. Patients with stage III NSCLC (without pleural effusion or cervical lymphadenopathy) were treated with thoracic RT (60 Gy in 30 fractions over 6 weeks) with concurrent weekly cisplatin 20 mg/m(2) and escalating doses of twice-weekly paclitaxel (starting dose of paclitaxel of 20 mg/m(2) increased in increments of 5 mg/m(2)) in successive cohorts of three to six patients until two or more patients experienced dose limiting toxicities (DLTs) at a particular dose level. All patients were planned to be given a further two cycles of consolidation chemotherapy consisting of paclitaxel 175 mg/m(2) and carboplatin AUC 5 after completion of RT. Twenty-five patients were enrolled in this study from two institutions. At a dose of paclitaxel 35 mg/m(2), two of four treated patients had DLTs (1 grade 3 oesophagitis and pulmonary toxicity; 1 grade 3 oesophagitis and infection). The recommended dose was therefore determined to be 30 mg/m(2) and a total of 15 patients were enrolled in an expanded cohort at this level. The overall response rate for all patients was 64% (95% CI: 43-82%). The estimated median survival was 23.6 months with an estimated 1-year and 2-year survival of 72 and 49%, respectively. Paclitaxel can be safely given twice-weekly at a dose of 30 mg/m(2) in combination with weekly cisplatin (20 mg/m(2)) and thoracic RT (60 Gy), and this regimen has significant activity in stage III NSCLC.

Effectiveness and cost-effectiveness of acute hospital-based spinal cord injuries services: systematic review

OBJECTIVES

To examine four key areas: (1) the effectiveness and cost-effectiveness of spinal fixation surgery, (2) the consequences of immediate versus delayed referral to a spinal injuries unit (SIU), (3) the number of people with a new spinal cord injury (SCI) who are discharged from hospital without ever being transferred to an SIU, and (4) the effectiveness and cost-effectiveness of steroids for people with SCI.

DATA SOURCES

Searches were carried out on several databases and also on the Internet. Specialist SCI and spinal injury related websites were searched, specifically the Spinal Injuries Association, the British Association of Spinal Cord Injury Specialists and the National Spinal Cord Injury Association.

REVIEW METHODS

Three separate search strategies were devised to find studies relating to the four key areas. Two reviewers independently screened all study citations for inclusion. The lists of all retrieved studies were scanned for additional studies. Quality of studies was assessed and data were extracted by one reviewer then checked by the second. Data from included studies were summarised within each key area. For dichotomous data, relative risks were calculated with 95% confidence intervals. Pooled relative risks were calculated as appropriate. For continuous data, mean differences with 95% confidence intervals were calculated and, if data were pooled, weighted mean differences were calculated. Searches were carried out to identify economic evaluations, details of these together with a critical appraisal of quality are presented in structured tables. Quality was assessed using a checklist supplemented with additional comments on the adequacy of methodology where appropriate.

RESULTS

For spinal fixation versus no fixation, 68 retrospective observational studies were found that suggested some benefits of fixation surgery. Only four studies were found on fixation surgery in SIUs compared with non-SIU hospitals and no significant differences were seen. All 28 studies concerning delayed referral to a SIU were retrospective observational studies. In most, study details were poorly reported and there was doubt over the comparability of groups at baseline and on confounding factors. Times of referral and transfer were not reported separately. Evidence suggested an effect in favour of the SIU group for neurological improvement. No relevant published studies of any design were found regarding how many people with a new SCI are discharged from hospital without ever being transferred to an SIU. Two systematic reviews were found that assessed the effectiveness of steroids. No studies were identified that considered both costs and the impact on patient outcomes of a given intervention.

CONCLUSIONS

Although there was evidence to suggest some benefits of fixation surgery and also a benefit of immediate referral to SIUs compared with delayed or no referral, owing to the limitations of the data these should be interpreted with caution. Not enough data were found to assess whether surgery is more beneficial when carried out in SIUs and further research is required in this area. Well-designed prospective observational studies with appropriately matched controls are needed. High-dose methylprednisolone steroid therapy may be effective in promoting some degree of neurological recovery if given within 8 hours of injury. There is a need for more randomised controlled trials (RCTs) of pharmacological therapy for acute SCI. No published studies of any design were found to answer the question of how many people with acute SCI are discharged from hospital without ever being transferred to an SIU. Primary research involving audit of selected hospital records should be commissioned and published. The search strategy did not identify any full economic evaluations. Future research should include full economic evaluations, possibly alongside a large RCT, which fully consider the costs and consequences of implementing interventions.

CliniMACS CD34-selected cells to support multiple cycles of high-dose therapy

BACKGROUND

Traditionally, following high-dose therapy (HDT), unmanipulated autologous PBPC are infused. Alternatively, purified CD34+ cells can now be obtained by immunomagnetic separation using the CliniMACS device. Limited data currently exist examining hemopoietic recovery with such cells.

METHODS

Ten patients with advanced breast cancer had PBPC mobilized with docetaxel (100 mg/m2) and G-CSF (10 microg/kg per day), harvested and processed using the CliniMACS CD34-selection device and equally divided into three aliquots for cryopreservation. Unmanipulated 'back-up' cells were also collected on a separate day of the same mobilization, divided into three and cryopreserved. Patients subsequently received three cycles of HDT with cyclophosphamide (4 g/m2), thiotepa (300 mg/m2) and paclitaxel (175 mg/m2). The intent was for patients to receive CD34-selected cells to support each of the three cycles of HDT (i.e., 1/3 for each cycle). If, however, hemopoietic recovery was delayed after Cycle 1, 1/3 of the unmanipulated cells were infused following Cycle 2 and the remaining CD34-selected cells (2/3) were used to support Cycle 3.

RESULTS

PBPC from 10 patients underwent CD34-selection with a resulting median purity of 93% (range: 76-98%) and yield of 62% (range: 16-93%). Of the 10 patients, only two were able to be supported with CD34-selected cells for all three cycles of HDT. The remaining eight patients required unmanipulated 'back-up' cells to support Cycle 2. Three patients also required infusion of 'back-up' unmanipulated cells because of persistent neutropenia (n = 1) or thrombocytopenia (n = 2) following cycles initially supported by CD34-selected cells. The median number of CD34-selected cells (x 10(6)/kg) infused per cycle was 1.5 (0.7-2.6) (n = 20) and unselected cells was 1.7 (1.4-2.8) (n = 10). Comparing hemopoietic recovery between cycles of HDT supported by CD34-selected (n = 20) and unmanipulated cells (n = 10) there was a significant slowing with the CD34-selected cells; time to ANC > 1.0 = 13 days versus 10 days, platelets > 20 = 17 days versus 13 days, > 50 = 25 versus 17 days (all P values < 0.001). There was no correlation between the dose of CD34-selected cells infused and neutrophil/platelet recovery.

DISCUSSION

We have demonstrated that, although unmanipulated PBPC achieve rapid hemopoietic recovery (at modest CD34 doses of < or = 2.8 x 10(6)/kg), CliniMACS-selected CD34+ cells (in the doses utilized in this study of < or = 2.6 x 10(6)/kg) result in significantly prolonged recovery.

Isolex 300i CD34-selected cells to support multiple cycles of high-dose therapy

BACKGROUND

We have previously reported that repeated cycles of high-dose therapy (HDT), can be supported by unmanipulated autologous PBPC. Here we investigate whether purified CD34+ cells, obtained by immunomagnetic separation using the Isolex 300i device, can support such therapy.

METHODS

Twenty-nine consecutive patients with metastatic breast cancer had PBPC mobilized and harvested following chemotherapy and G-CSF (10 microg/kg per day). Patients with > 4.0 x 10(6)/kg CD34+ cells in the apheresis product underwent CD34-selection using the Isolex 300i (v2.0) device. All cells collected were equally divided into three aliquots and cryopreserved. Patients who did not achieve this threshold had unmanipulated cells collected and stored. Patients subsequently received three cycles of HDT with paclitaxel (175 mg/m2), thiotepa (300 mg/m2) and either ifosfamide (10 g/m2) or cyclophosphamide (4 g/m2). It was intended for patients to receive CD34-selected cells to support each of the three cycles of HDT (i.e 1/3 for each cycle) and to compare hemopoietic recovery between patients receiving CD34-selected cells or unmanipulated cells.

RESULTS

Thirteen of the 29 patients (45%) did not mobilize sufficient CD34+ cells to undergo CD34-selection. The remaining 16 patients underwent CD34-selection with a median purity of 84.3% (range: 16.3-96.1%) and yield of 34% (range: 1-60%). Fifteen of these patients proceeded to HDT and 42 of the planned 45 cycles were administered. Nine patients had all three HDT cycles supported by CD34-selected cells. The median number of CD34-selected cells (x 10(6)/kg) infused per cycle was 1.5 (range: 0.04-3.01). Three of the 15 patients required infusion of 'back-up' unmanipulated cells because of delayed neutrophil recovery. Of the 13 patients whose PBPCs did not undergo CD34+ cell selection, 11 proceeded to HDT with a median of 3.2 x 10(6)/kg (range: 2.0-4.4) unselected cells infused per cycle and 31 of 33 planned cycles were delivered. When hemopoietic recovery was compared between cycles of HDT supported by CD34-selected (n = 34) and unmanipulated cells (n = 31), there was a modest slowing in the patients receiving CD34-selected cells; time to ANC > 1.0 x 10(9)/L = 11 days versus 10 days (P = 0.0122) and platelets > 20 x 10(9)/L = 14 days versus 13 days (P = 0.0009). No difference in recovery to 50 x 10(9)/L was observed (P = 0.54).

CONCLUSION

We have demonstrated that Isolex 300i CD34-selected cells are capable of supporting multiple cycles of HDT. However, we were unable to acquire sufficient CD34+ cells to perform this processing in 45% (13/29) of patients and further improvements in yield are required to overcome the modest delay in neutrophil and platelet recovery.

The ingestion of inorganic nitrate increases gastric S-nitrosothiol levels and inhibits platelet function in humans

Platelets play an important role in the development of vascular disease, while vegetarian diets, which are rich in inorganic nitrate, protect against it. This study was performed to assess the effect of potassium nitrate (KNO(3)) ingestion on platelet function in humans. Oral KNO(3) (2 mmol) was given to healthy volunteers and its effect on platelet function assessed by measuring the aggregant effect of collagen. Blood samples were taken for measurement of plasma S-nitrosothiols (RSNO) and platelet cyclic GMP and nitrotyrosine levels. Gastric juice samples were taken for measurement of RSNO. In a separate study, the effect of oral KNO(3) on portal RSNO levels in patients with intrahepatic porto-systemic shunts was assessed. KNO(3) caused a significant increase in gastric RSNO levels, from 0.46 +/- 0.06 to 3.62 +/- 2.82 microM (t(max) 45 min; P < 0.001), and significantly inhibited platelet function (t(max) 60 min; P < 0.001). There was no effect on systemic or portal RSNO, platelet cGMP or platelet nitrotyrosine levels. Oral KNO(3) inhibits platelet aggregation. The time course suggests that gastric RSNO production may be involved in this effect. The protection against vascular events associated with a high intake of vegetables may be due to their high nitrate content.

Potential therapeutic uses for S-nitrosothiols

The S-nitrosothiols (RSNOs) are thought to represent a circulating endogenous reservoir of nitric oxide (NO), and may have potential as donors of NO, distinct from currently used agents. They have the general formula RSNO, and naturally occurring examples include S-nitrosocysteine, S-nitrosoglutathione and S-nitrosoalbumin, in which R is an amino acid, polypeptide and protein respectively. RSNOs have anti-platelet properties, a theoretical role in the treatment of asthma and the potential to be used as agents to treat infectious diseases ranging from the common cold to AIDS. RSNOs are relatively unstable, being degraded to release NO and the corresponding disulphide. Their stability is influenced by the properties of the R group, heat, light, the presence of transition metal ions (in particular copper) and the presence of other thiols. RSNOs participate in transnitrosation reactions in which the -NO group is transferred to another thiol to form a more stable RSNO. Thus the stability of RSNOs in vivo is difficult to predict, and this has led to the development of more stable analogues, in which the properties of R are modified. Potential interactions of RSNOs include that with ascorbic acid (vitamin C), which enhances the ability of copper to catalyse their degradation. Transnitrosation reactions with thiol-containing enzymes can influence protein function, and the intracellular thiol glutathione, levels of which are influenced by many disease states, can also influence stability. Thus, although RSNOs have many theoretically useful properties, there are also many aspects of their biochemistry that need to be addressed before their therapeutic potential can be fully realized.

Retardation of cochlear maturation and impaired hair cell function caused by deletion of all known thyroid hormone receptors

The deafness caused by early onset hypothyroidism indicates that thyroid hormone is essential for the development of hearing. We investigated the underlying roles of the TRalpha1 and TRbeta thyroid hormone receptors in the auditory system using receptor-deficient mice. TRalpha1 and TRbeta, which act as hormone-activated transcription factors, are encoded by the Thra and Thrb genes, respectively, and both are expressed in the developing cochlea. TRbeta is required for hearing because TRbeta-deficient (Thrb(tm1/tm1)) mice have a defective auditory-evoked brainstem response and retarded expression of a potassium current (I(K,f)) in the cochlear inner hair cells. Here, we show that although TRalpha1 is individually dispensable, TRalpha1 and TRbeta synergistically control an extended array of functions in postnatal cochlear development. Compared with Thrb(tm1/tm1) mice, the deletion of all TRs in Thra(tm1/tm1)Thrb(tm1/tm1) mice produces exacerbated and novel phenotypes, including delayed differentiation of the sensory epithelium, malformation of the tectorial membrane, impairment of electromechanical transduction in outer hair cells, and a low endocochlear potential. The induction of I(K,f) in inner hair cells was not markedly more retarded than in Thrb(tm1/tm1) mice, suggesting that this feature of hair cell maturation is primarily TRbeta-dependent. These results indicate that distinct pathways mediated by TRbeta alone or by TRbeta and TRalpha1 together facilitate control over an extended range of functions during the maturation of the cochlea.