Overexpression of the TXNDC5 protein in non-small cell lung carcinoma

Thioredoxin domain containing protein 5 (TXNDC5) is a member of the thioredoxin (Trx) domain-containing family of proteins that have been implicated in cancer progression. The expression of TXNDC5 in non-small cell lung carcinoma (NSCLC) tumours compared to patient-matched normal lung tissue was determined and cell line models were used to determine if expression was regulated by hypoxia.

PATIENTS AND METHODS

Samples of tumour and normal lung tissue were taken during surgery and immediately frozen. The expression of TXNDC5 was determined by Western blotting and immunohistochemistry. To analyse the effect of hypoxia on TXNDC5 expression NSCLC cell lines were used.

RESULTS

Tumours from 18/29 (62%) individuals exhibited an increase in TXNDC5 expression compared to normal lung tissue (p<0.05). TXNDC5 expression was not elevated by hypoxia.

CONCLUSION

TXNDC5 is up-regulated in the majority of resected human NSCLC. Cell line data indicates that the expression of TXNDC5 in tumour cells is not regulated by hypoxia.

Long-term follow-up of ultraflex metallic stents in benign and malignant central airway obstruction

BACKGROUND

We report experience with Ultraflex metallic stents (Boston Scientific, Natick, MA) inserted at rigid bronchoscopy under general anesthesia for palliation of benign and malignant upper airway obstruction.

METHODS

Notes of all patients treated with Ultraflex stents from 1999 to 2003 were reviewed for symptomatic response, spirometric data, and any complications before discharge home. Long-term outcome was assessed by questionnaires sent to patients' general practitioners.

RESULTS

Recruited were 66 patients (12 benign, 54 malignant airway obstructions). Before discharge home, breathlessness improved in 11 of 12 patients with benign obstruction and in 39 of 54 with malignancies. Postoperative complications in 10 patients with malignant obstructions and in 2 patients with benign obstruction were successfully controlled. It was not possible to perform preoperative pulmonary function tests in most of the patients who presented as emergencies. Mean improvement in forced expiratory volume in 1 second was 0.88 liters in 3 patients with benign obstruction and 0.28 liters in 14 patients with malignant obstruction, and mean peak expiratory flow rate improved by 109 L/min and 97 L/min, respectively. General practitioners completed questionnaires for 12 benign patients and 46 of 54 patients with malignancies. At a mean follow-up of 1017 days (range, 46 to 1120 days), 10 of the 12 patients with benign disease were alive and 7 of 46 patients with malignant airway obstruction were alive, with a median survival of 128 days (mean, 361; range, 3 to 1859 days). Most survivors had Medical Research Council grade III breathlessness or better, with few stent-related symptoms.

CONCLUSIONS

Ultraflex stents proved safe and effective in prolonged palliation of benign and malignant airways obstruction.

Interstitial laser photocoagulation and interstitial photodynamic therapy of normal lung parenchyma in the pig

Interstitial laser photocoagulation (ILP) and interstitial photodynamic therapy (PDT) involve delivery of light to lesions in solid organs using thin fibres passed through needles inserted percutaneously under image guidance. In ILP, the laser energy heats the tissue, whereas in PDT it activates a previously administered photosensitising agent. This study looks at their potential for treating localised, small, peripheral lung cancers in patients unsuitable for surgery. Experiments were undertaken on nine normal pigs, up to four fibres being inserted into the lung parenchyma percutaneously under X-ray guidance (ILP: 2-3 W, 1000 q/fibre, from 805 nm diode laser, PDT, 100-200 J/fibre from 652 nm diode laser at 50-100 W, 3 days after 0.15 mg/kg mTHPC). Animals were killed from 3 days to 3 months later and the treated areas examined macroscopically and microscopically. Both techniques were well tolerated, producing well-defined, localised lesions, typically 3.5 x 2 x 2 cm using four fibres. Histology showed thermal coagulative necrosis after ILP and haemorrhagic necrosis after PDT. Early small haematomas and late cavitation were sometimes seen after ILP, but not after PDT. PDT lesions healed with preservation of larger arteries and bronchi in the treated area. A few small pneumothoraces were seen which resolved spontaneously, probably related to the chest wall puncture. It was concluded that ILP and PDT lesions of a size large enough to cover a small tumour can be made safely in the lung parenchyma, although healing was better after PDT. Pilot clinical studies with both techniques are now justified on carefully selected patients.

Fine-needle interstitial photodynamic therapy of the lung parenchyma: photosensitizer distribution and morphologic effects of treatment

STUDY OBJECTIVE

To look at the effect of interstitial photodynamic therapy (PDT) in normal lung parenchyma to assess its potential for treating localized, peripheral lung tumors.

DESIGN

Studies were performed on normal Wistar rats using the photosensitizer meso-tetrahydroxyphenyl chlorine. Drug distribution was measured by fluorescence microscopy on tissue sections. Light was delivered to the lungs via a single fiber inserted percutaneously under x-ray control and the PDT effect studied in animals killed at times up to 6 months later.

RESULTS

Fluorescence studies showed that the drug was initially distributed throughout the lung, but was later predominantly in the vasculature, bronchi, and macrophages. PDT produced sharply defined zones of hemorrhagic necrosis up to 12 mm in diameter that healed with regeneration of bronchial epithelium and local fibrosis. Different histologic effects were seen between drug light intervals of 1 and 3 days. Treatment was well tolerated, there was a low incidence of pneumothorax, and as long as the fiber tip was within the lung parenchyma, there was no damage to adjacent tissues.

CONCLUSION

Interstitial PDT produces zones of necrosis in normal lung that heal safely by a percutaneous technique without affecting adjacent areas of untreated lung. If the lesion size can be increased by using multiple fibers, this could be a promising new technique for treating localized, peripheral lung cancers in patients who are unfit for surgery.

Multi-centre clinical respiratory research: a new approach?

BACKGROUND

Recruitment to clinical trials organised by the research committee of the British Thoracic Society (BTS) has declined. We suspected that this was due to increasing workloads for consultant physicians in the National Health Service (NHS). We investigated possible causes in study 1 and a possible solution in study 2.

METHODS

Study 1--a questionnaire was sent to BTS members listing possible factors that might deter them from entering patients into trials. These were scored on a 0-5 scale. Study 2--we set up 13 panels of experts to cover all major fields of respiratory medicine. They were asked to design projects that would address the most important research questions that could be answered by multi-centre clinical trials. We sent 11 projects for scoring to consultant members of the BTS who were asked to score them on scientific merit and on their ability to contribute patients to the study.

RESULTS

Study 1--of the 59% of consultants who responded, 77% said that competition with increasing demands on their time was the major reason for not participating. Study 2--40% of consultants returned project scores. Three projects were subsequently selected for grant application.

CONCLUSIONS

Clinical research in the UK is under threat from increasing workloads on consultants. One solution to this problem is a national approach to commission major projects. The most important clinical research questions might then still be answered in the limited time available to consultants.

Interstitial laser photocoagulation of normal lung parenchyma in rats

BACKGROUND

Management of peripheral lung tumours may be risky in patients with poor lung function or in the elderly. A new possibility is interstitial laser photocoagulation (ILP) in which tumours are gently coagulated using thin laser fibres placed percutaneously under radiological guidance. This could have a useful palliative role in selected patients, but to be safe the effects on normal lung parenchyma must first be understood. This paper describes the creation and healing of ILP lesions in the normal rat lung.

METHODS

ILP was performed using single laser fibres placed percutaneously in the left lung of normal rats under general anaesthetic with radiological guidance (laser power 1-3 W at 805 nm, treatment time 250-1000 s). The lesion size and healing were studied in rats killed at times from three days to six months after treatment, the bursting pressure was measured, and any complications noted.

RESULTS

Zones of necrosis up to 12 mm in diameter were produced, the size depending on the laser power and treatment time. Histological examination showed typical thermal effects with complete healing with fibrosis by two months. The effect was very localised with remarkably little effect on the structure and function of the rest of the lung. Adverse effects in the lung parenchyma only occurred if the ILP lesion involved the hilar vessels or the oesophagus, causing pulmonary congestion and perforation, respectively. Pneumothorax was seen in 6% of cases.

CONCLUSIONS

ILP with a single fibre can produce a localised zone of necrosis in normal lung parenchyma which heals safely and which has little effect on the rest of the lung. Further study of this technique using multiple fibres in a larger animal model is warranted to see if it is feasible and safe to produce a large enough volume of necrosis to be of value in the treatment of small peripheral lung tumours in patients who are unsuitable for surgery or palliative radiotherapy.

Primary tracheal tumours: a national survey

BACKGROUND

Primary tracheal tumours are rare, so few physicians have extensive experience of their management. No direct comparisons have been made of surgical and radiotherapy treatment.

METHODS

A postal survey of cases presenting in the last 10 years in the United Kingdom was conducted. Results were expressed as cumulative survival and survival curves were compared by the log rank test.

RESULTS

Three hundred and twenty one patients were recruited. Overall five year survival rates were 25% for squamous cell carcinomas, and 80% for adenoid cystic carcinoma; 62% received radiotherapy but only 10% underwent surgery. Small cell carcinoma was more common than expected with an incidence of 6%. In patients with squamous carcinoma improved survival was seen in those with tumour in the upper trachea. High dose radiotherapy was more effective than low dose only in tumours of the upper trachea and in squamous carcinoma. In adenoid cystic carcinoma no significant difference in survival rate was seen between treatment with radiotherapy and surgery. No histological diagnosis was made in 44 patients, the most common reason being fear over the safety of fibreoptic bronchoscopy; however, this group had a cumulative survival at five years of 46%.

CONCLUSIONS

Survival may be somewhat better in cases with tracheal tumours than in those with bronchial tumours. Small cell carcinoma is less rare than was previously thought. Upper tracheal tumours may merit more aggressive therapy. It is important to make a histological diagnosis even if rigid bronchoscopy is necessary, and referral to specialist centres is recommended. A larger prospective study is required to compare the value of surgery and radiotherapy.

Experimental studies to assess the potential of photodynamic therapy for the treatment of bronchial carcinomas

BACKGROUND

Photodynamic therapy (PDT) is a technique for producing localised tissue necrosis with light after prior administration of a photosensitising drug. There is some selectivity of uptake of photosensitisers in malignant tissue, although this is difficult to exploit. Full thickness necrosis in normal and neoplastic colon heals without perforation because of a lack of effect on collagen, making local cure a possibility. The experiments described here aim to establish whether these conclusions are also valid for bronchial tumours.

METHODS

In pharmacokinetic studies normal rats were given 5 mg/kg of the photosensitiser aluminium sulphonated phthalocyanine (A1SPc) intravenously and killed up to one month later. The distribution of A1SPc in the trachea was measured by chemical extraction and fluorescence microscopy. In subsequent experiments sensitised animals were treated with light delivered to the tracheal mucosa through a thin flexible fibre and the resultant lesions were studied for their size, mechanical strength, and healing. A series of resected human bronchial carcinomas were examined histologically for their collagen content.

RESULTS

The tracheal concentration of A1SPc in normal rats was maximum 1-20 hours after administration. Fluorescence microscopy revealed that most was in the perichondrium and submucosal stroma, with little in the cartilage. Light exposure showed necrosis of the soft tissues which healed by regeneration, but no effect on cartilage and no reduction in the mechanical strength of the trachea at any stage. Histological examination of resected human bronchial carcinomas showed more collagen in the tumour areas than would be found in normal regions.

CONCLUSIONS

PDT leads to necrosis of the soft tissues of the normal trachea but there is complete healing by regeneration, no risk of perforation (due to collagen preservation), and no effect on cartilage. Human bronchial carcinomas apparently contain more collagen than normal bronchi which may give protection against perforation following necrosis induced by PDT. PDT may have a role in eradicating small volumes of tumour tissue in situ and could be valuable for treating (1) small carcinomas in patients unfit for resection, (2) tumour remaining after surgical resection, (3) stump recurrences, or (4) to prolong palliation of tumours after debulking with the NdYAG laser.

Value of pulse oximetry in screening for long-term oxygen therapy requirement

Pulse oximetry, combined with spirometry, was evaluated as a method of selecting chronic obstructive pulmonary disease (COPD) out-patients requiring definitive arterial blood gas analysis for long-term oxygen therapy (LTOT) assessment. A relatively high screening arterial oxygen saturation by pulse oximetry (SaO2) level was set, in order to maximize sensitivity. All 113 COPD out-patients attending the hospital clinic over a 6 month period were screened. Sixty had a forced expiratory volume in one second < 1.5 l and 26 had an SaO2 < or = 92%. These 26 underwent arterial blood gas analysis. Nine had an arterial oxygen tension < 7.3 kPa all with an arterial carbon dioxide tension (PaCO2) > 6 kPa. A further eight had a PaO2 < 8 kPa. This produced a sensitivity of 100% and specificity of 69% for oximetry in the detection of PaO2 < 7.3 kPa determined by direct arterial puncture and 100% and 86% respectively for detecting a PaO2 < 8 kPa. Although the poor specificity of oximetry in the crucial PaO2 range makes it unsuitable, when used alone, for prescription of LTOT, it may prove valuable in selecting patients who require further definitive arterial blood gas analysis.

Value of pulse oximetry in screening for long-term oxygen therapy requirement

Pulse oximetry, combined with spirometry, was evaluated as a method of selecting chronic obstructive pulmonary disease (COPD) out-patients requiring definitive arterial blood gas analysis for long-term oxygen therapy (LTOT) assessment. A relatively high screening arterial oxygen saturation by pulse oximetry (SaO2) level was set, in order to maximize sensitivity. All 113 COPD out-patients attending the hospital clinic over a 6 month period were screened. Sixty had a forced expiratory volume in one second < 1.5 l and 26 had an SaO2 < or = 92%. These 26 underwent arterial blood gas analysis. Nine had an arterial oxygen tension < 7.3 kPa all with an arterial carbon dioxide tension (PaCO2) > 6 kPa. A further eight had a PaO2 < 8 kPa. This produced a sensitivity of 100% and specificity of 69% for oximetry in the detection of PaO2 < 7.3 kPa determined by direct arterial puncture and 100% and 86% respectively for detecting a PaO2 < 8 kPa. Although the poor specificity of oximetry in the crucial PaO2 range makes it unsuitable, when used alone, for prescription of LTOT, it may prove valuable in selecting patients who require further definitive arterial blood gas analysis.

Tracheal tumours: could treatment be better?

The rarity of primary tracheal tumours makes research into their natural history and treatment very difficult. Diagnosis is often made too late for cure. Palliation has improved with the introduction of laser resection, brachytherapy and stents. Squamous cell carcinoma may have a better prognosis in the trachea than in the lung. It has been assumed that surgery is the treatment of choice and up to 50% of the trachea can be resected with modern techniques. However, several of the largest surgical series have used mostly post-operative radiotherapy and really represent the results of combined therapy. High dose radiotherapy may achieve cure in some cases. Prospective studies of the relative merits of surgery and radiotherapy are urgently needed. The British Thoracic Society Research Committee is launching a national study at the present time.

The role of computed tomography (CT) in the investigation of unexplained haemoptysis

Forty patients with a history of haemoptysis, normal chest radiographs apart from evidence of chronic airflow limitation, and normal fibreoptic bronchoscopy (or blood alone in the bronchial tree) were investigated by computed tomography (CT). Abnormalities were seen in 20 (50%) of the CT scans. Seven of the patients had evidence of bronchiectasis (18%), one of whom also had a mass. In four (10%) cases a mass alone was detected (two tuberculous, two malignant). In a further four (10%) scans alveolar consolidation was present and in three cases abnormal vessels were detected (7.5%). One patient had cystic changes shown in their scan and multiple nodules were shown in the final patient. The contralateral lungs of 93 patients undergoing CT for pre-operative assessment of bronchogenic carcinoma were used as controls. In six (6%) of these patients abnormalities were detected by CT. Pleural nodules were observed in two patients, fat in the transverse fissure in another, atelectasis in two patients and an apical bulla in the other abnormal scan. The relative risk for patients with unexplained haemoptysis having abnormal CT scans compared to the control group of patients was 7.75. We conclude that computed tomography is of value in the investigation of patients with unexplained haemoptysis.

Endoscopic palliation of tracheobronchial malignancies

The prognosis for tracheobronchial tumours remains poor. Most patients can be offered only palliation. When the main symptom is breathlessness or refractory haemoptysis from a large airway tumour endoscopic treatment may be very effective. Over the last decade most attention has focused on the neodymium YAG laser. This often produces dramatic effects but has some important limitations. In the last few years better techniques for stenting and intrabronchial radiotherapy (brachytherapy) have also been developed. This article discusses the range of techniques now available and aims to help clinicians decide which patients may benefit from referral to centres providing these techniques.

Bronchography in the assessment of patients with lung collapse for endoscopic laser therapy

In an attempt to improve selection of patients and the efficacy of endoscopic laser treatment, a bronchographic technique has been developed for patients with tumours causing complete endobronchial obstruction. This technique has shown patent distal airways in 16 out of 17 patients with a collapsed lung or lobe. These airways were abnormally dilated in each case, suggesting bronchiectasis. In one patient the appearances of bronchiectasis were sufficiently severe to decide against attempting treatment. Treatment was not attempted in another patient as a large cavity was seen within the collapsed lung and this was thought to carry a risk of postoperative infection and haemorrhage. Treatment with a neodymium YAG laser under general anaesthesia successfully recanalised the airway in 12 of the 15 remaining patients and was associated with a substantial reduction in breathlessness. The procedure was abandoned prematurely in one patient because of life threatening haemorrhage. In the remaining two patients in whom treatment was unsuccessful bronchography had suggested very extensive endobronchial obstruction. Spirometry and radionuclide lung scans were performed before and after treatment in eight patients treated successfully and showed significant improvements. Four patients were investigated within two weeks of lung re-expansion by repeat bronchography (three patients) or computed tomography (one patient); in each case the calibre of the airways had returned almost to normal. Thus the radiological demonstration of bronchial dilation in a collapsed lung does not necessarily imply a diagnosis of irreversible bronchiectasis and should not be regarded as a contraindication to treatment. It is concluded that preoperative bronchography provides reliable data on the extent of tumour, the patency of the distal airways, and presence of extensive cavitation. This information should facilitate successful laser treatment.

Elective resection of tumours of the trachea and main carina after endoscopic laser therapy

In our patients with tumour affecting the trachea or carina elective surgery was carried out after endoscopic laser treatment. Laser treatment was performed as an emergency procedure in three of the patients, who presented with impending asphyxia; the improvement provided time in which to assess the disease, withdraw corticosteroids, and treat infection. The fourth patient was treated with the laser for life threatening haemoptysis, but further bleeding made it necessary to tamponade the tumour with a cuffed endotracheal tube for 24 hours. Elective resections of the trachea (three cases) and carina (one case) were performed successfully four to eight weeks after laser treatment. Frozen sections of the resection margins were clear in all cases and paraffin sections subsequently confirmed the localised nature of the lesions. All patients are alive and well with no evidence of tumour recurrence after 18 months to 4 years. Laser therapy appears to be an ideal preoperative treatment for patients with impending asphyxia but it may be of limited value in controlling very brisk haemorrhage.

Value of washings and brushings at fibreoptic bronchoscopy in the diagnosis of lung cancer

A retrospective study was performed to evaluate the diagnostic yield for lung cancer from histological biopsy specimens and from washings and brushings for cytological examination taken at fibreoptic bronchoscopy. The records of 680 bronchoscopies were analysed. Of 300 patients eventually diagnosed as having a malignant lesion, 188 had had biopsy, washing, and brushing. Of these, 125 had endoscopically visible tumour (group A) and 63 had no abnormal findings or abnormal findings that were not diagnostic of malignancy (group B). In group A biopsy specimens gave a positive result in 76% of cases, washings in 49.6%, and brushings in 52%; biopsy material gave the only positive result in 22.4% of cases, washings in 2.2%, and brushings in 4.8%. In group B biopsy specimens were positive in 36.5%, washings in 38.1%, and brushings in 28.6%; biopsy gave the only positive result in 11.1% of cases, washing in 9.5%, and brushing in 3.2%. Washing had a higher diagnostic yield than brushing in group B. Biopsy and cytological examination of either washings or brushings were found to give over 95% of all positive results in group A, but in group B the combination of biopsy and washing was more often successful (94.3%) than biopsy and brushing (82.8%). It is concluded that for the maximum diagnostic yield in the diagnosis of lung cancer biopsy should be combined with cytology using both washings and brushings.

Changes in regional ventilation and perfusion of the lung after endoscopic laser treatment

To determine whether endoscopic laser treatment improves both ventilation and perfusion in patients with advanced lung cancer, krypton-81m ventilation and technetium-99m labelled macro-aggregate perfusion scanning was performed immediately before and two or four days after treatment in a consecutive series of 28 patients. Twelve patients had not received any other treatment before laser therapy and 16 had undergone previous treatments that included radiotherapy. Ventilation and perfusion were quantified by expressing the number of counts in the affected lung as a percentage of the total counts. Ventilation and perfusion improved after laser treatment in 23 patients (82%). The mean ventilation score in the affected lung rose by 50% (p less than 0.001) and the mean perfusion score rose by 24% (p less than 0.001). Incremental changes in ventilation and perfusion scores were positively correlated (r = 0.80). Mean spirometric values, six minute walking distance, the Karnofsky performance index, and breathlessness and wellbeing scores also improved significantly. Patients with main bronchial obstruction who had had no radiotherapy showed the most striking improvements. It is concluded that the removal of intraluminal tumour from the bronchial tree leads to matched improvements in ventilation and perfusion in most patients and that this is associated with valuable improvement in symptoms.

Endoscopic applications of lasers in the bronchial tree

Bronchial carcinoma causes some 30,000 deaths per year in the UK and only 10-20% of patients have any chance of surgical care. Radiotherapy and chemotherapy are mainly palliative treatments, yet they have considerable toxicity. In recent years laser bronchoscopy, with its advantages of speed, safety and freedom from toxicity, has proved a valuable addition to the established palliative therapy.

Cryptogenic bilateral fibrosing pleuritis

We describe four patients with bilateral pleural effusions progressing to diffuse pleural thickening for which we have been unable to find any evidence of an infective, embolic or occupational aetiology. In order to avoid confusion with diffuse pleural thickening attributable to asbestos-related disease, the term cryptogenic bilateral fibrosing pleuritis is suggested. The patients differed from those with pleural shadowing due to asbestos in that none of them gave a history of asbestos exposure, all were ill, presented with chest pain which was not always pleuritic in character, and had dyspnoea, cough or malaise. They had pleural effusions of variable size, pleural shadowing radiographically and raised sedimentation rates. Computed tomography revealed bilateral extensive pleural thickening in all cases. All four were HLA B44 positive. Histology showed that in all cases the pleura was thickened by fibrous tissue. Both layers were affected and the pleural space was often obliterated. Otherwise the pleural surface was covered by organizing fibrin. Focal collections of lymphocytes were often present when the fibrous tissue abutted on the subpleural fat. No asbestos bodies were seen in any of the cases and in one patient electron microscopic fibre counts showed no excess of asbestos. Pleural decortication was successful in three patients. In one of these, contralateral disease was successfully controlled with corticosteroids, but the fourth patient has not improved on corticosteroids.

Laser treatment for tracheobronchial tumours: local or general anaesthesia?

Ninety seven patients with tracheobronchial tumours have been treated with the neodymium yttrium-aluminium-garnet (Nd YAG) laser over a period of 33 months. Fifty one of these patients were treated under local anaesthesia and 46 under general anaesthesia. The results obtained with the two methods have been compared retrospectively. The numbers of patients responding to treatment, the magnitude of the response, and the duration of palliation were similar in the two groups; significantly more treatment sessions, however, were required during each course of treatment under local anaesthesia. This advantage of general anaesthesia was thought to arise from the ability to continue treatment for longer and with greater efficiency. The use of the rigid bronchoscope with jet ventilation under general anaesthesia was also thought to provide better control of the airway and to allow more efficient clearance of blood and mucus. Two operative deaths occurred under local anaesthesia, when bleeding led to asphyxiation, but none have occurred under general anaesthesia. Treatment under general anaesthesia is not, however, without risk and is potentially hazardous in patients with severe chronic hypoxic lung disease.

Role of the neodymium YAG laser in the management of tracheal tumours

Twenty one patients with tracheal tumours (10 primary and 11 secondary) have been treated with the neodymium YAG laser under general anaesthesia. Fourteen of these patients presented with impending asphyxia and in 11 cases this was dramatically relieved with emergency laser treatment. The improvements in peak expiratory flow (PEF) ranged from 26% to 512%. The three patients who did not respond were immediately given other treatments but died in hospital. The remaining seven patients were not in severe respiratory distress and were treated electively; all were thought to have benefited from their treatment, the mean increase in PEF being 36%. The improvement obtained in the 11 patients who responded to emergency laser treatment provided time in which to assess the disease carefully and plan the most appropriate longer term management with surgery, radiotherapy, tracheal stenting, or repeat laser treatment. The patients who were treated electively have either not required further treatment of have been managed with repeat laser treatments alone. Laser treatment provides an excellent method of resuscitating patients with life threatening tracheal obstruction and enables subsequent management to be carefully planned. In some cases this longer term management should be with further laser treatment alone.

Maximal expiratory flow-volume curves in Londoners aged 60 years and over

To obtain more accurate information about respiratory function in the elderly, we carried out spirometry and constructed maximum expiratory flow-volume curves in 136 volunteers over the age of 60 years (90 women, 46 men). Significant age related differences were found. Although vital capacity appeared well preserved in all groups, mid expiratory flow rates were low, even in lifelong non-smokers. On the basis of previous work, many of the subjects in this study would have been assessed as having small airways obstruction. The number of subjects is larger than in previous studies of airflow in this age group. Old people have often smoked, and many have a history of cardiovascular disease. Such individuals were included provided that they were fit and active for their age, and had no overt respiratory disease. It is argued that our findings will be of more clinical relevance to the elderly population than values derived either from population studies or studies that have used rigorous selection criteria to exclude subjects who smoked or had a history of non-respiratory disease.

Resuscitative laser photoresection of a tracheal tumour before elective surgery

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The pharmacokinetics of uniphyllin in nocturnal asthma

Three consecutive doses of approximately 10 mg/kg of a once daily slow-release theophylline preparation (Uniphyllin) were given at 22.00 hours to 15 patients with nocturnal asthma who were recovering from an acute exacerbation of their asthma. Twenty-four hour plasma theophylline profiles were obtained after the first and third doses. Following the first dose, the mean peak level was 12.5 mg/litre, mean time to peak was 8.1 hours and mean apparent elimination half-life was 6.6 hours. Pharmacokinetic data were similar following the third dose. In nocturnal asthma, Uniphyllin should be given at about 20.00 hours to coincide peak levels with the time of maximum airflow obstruction.

Fibrosing pleuritis with extrathoracic extension

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Amyloidosis of the respiratory tract treated by laser therapy

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Laser therapy in 100 tracheobronchial tumours

One hundred patients with tracheobronchial tumours were treated with the neodymium YAG (yttrium-aluminium-garnet) or argon laser for symptoms of airways obstruction caused by tumour (59 cases), complete collapse of a lung (17 cases), or recurrent haemoptysis (24 cases). Seventy four of them had relapsed or failed to respond to radiotherapy or chemotherapy and all were inoperable. Objective improvement in results of lung function tests or haemoptysis diary charts was seen in 37 patients with airways obstruction (63%), five (29%) with collapsed lung, and 14 (58%) with haemoptysis. Overall, 68 patients had symptomatic benefit and there was objective improvement in 56. Two deaths occurred in 288 treatment sessions both occurring as a result of asphyxia from minor haemorrhage in patients with advanced cylindromas and critical narrowing of the trachea or single remaining bronchus. In suitable patients with intraluminal tumour laser phototherapy is a valuable addition to conventional treatment.

Metabolic oxidation phenotypes as markers for susceptibility to lung cancer

That bronchial carcinoma is not an inevitable consequence of cigarette smoking has stimulated the search for host factors that might influence the susceptibility of the individual smoker. One plausible host factor would be a polymorphic gene controlling the metabolic oxidative activation of chemical carcinogens, giving rise to wide inter-subject variation in the generation of cancer-inducing and/or promoting species. Recently, three genetic polymorphisms of human metabolic oxidation have been demonstrated (as characterized by debrisoquine, mephenytoin and carbocysteine), with the metabolism of several substrates exhibiting the phenomenon. Debrisoquine 4-hydroxylation segregates into two human phenotypes, each comprising characteristic metabolic capability. We report here the frequency of debrisoquine 4-hydroxylation phenotypes in age-, sex- and smoking history-matched bronchial carcinoma and control patients. Cancer patients showed a preponderance of probable homozygous dominant extensive metabolizers (78.8%) with few recessive poor metabolizers (1.6%) compared with smoking controls (27.8% and 9.0% respectively). We conclude that the gene controlling debrisoquine 4-hydroxylation may be a host genetic determinant of susceptibility to lung cancer in smokers and that it represents a marker to assist in assessing individual risk.

Laser treatment for carcinoma of the bronchus

Laser treatment in carcinoma of the bronchus is essentially palliative and is suitable for only a few patients. Patients selected for laser treatment must have predominantly endobronchial growth with normal bronchial anatomy still identifiable and symptoms due to the obstruction or to haemoptysis. A total of 34 patients with carcinoma of the bronchus were treated with argon gas or neodynium yttrium aluminium garnet crystal lasers. Good palliation was obtained in just over half the cases of partial obstruction of the trachea or main bronchus, but best results were obtained in lesions of the trachea or main carina. Re-expansion of the collapsed lung was achieved in some cases but with considerable risk of pneumonia. Haemoptysis was controlled at least partly in several cases. Laser treatment has the advantage of having no toxicity or dose limit and may be used in cases of poor respiratory function. The procedure was better tolerated than radiotherapy or chemotherapy and its relatively lower cost may justify setting up laser units in major cities.

Do oral and inhaled terbutaline have different effects on the lung?

The effect of inhaled or oral terbutaline on the subsequent response to inhaled terbutaline was studied using a double-blind cross-over technique in 12 asthmatic patients. 12 indices of respiratory function were obtained from the maximal flow-volume loop and a single-breath inert gas technique. These were used to evaluate the effect and to attempt to distinguish the site of action of the drug. Although the initial dose of inhaled terbutaline had a greater immediate effect than its oral counterpart there were no significant differences in the response to subsequently inhaled terbutaline. These findings do not support recent suggestions that oral administration has a greater effect on distal airways or promotes the effects of inhaled bronchodilators.

Regular versus symptomatic aerosol bronchodilator treatment of asthma

Regular treatment with salbutamol or placebo aerosols was compared in a double-blind study in 18 asthma patients. Although symptom scores and respiratory function tests were not significantly different, wheezing attacks requiring additional puffs of a standard salbutamol aerosol were significantly more frequent during the period on placebo when patients were receiving symptomatic treatment only. Thus regular treatment with bronchodilator aerosols provides better control of asthma than symptomatic use alone.

Comparison of normal and asthmatic circadian rhythms in peak expiratory flow rate

A computer technique (cosinor analysis) has been used to evaluate circadian rhythms in airway calibre in normals and asthmatics. Two hundred and twenty-one normal subjects recorded peak expiratory flow rate (PEFR) at home four times a day for seven days. Rhythm detection was statistically significant in 145 of them (65.6%) who showed a mean amplitude of 8.3% of individual mean PEFR (+/- SD 5.2%). Amplitude was independent of age, sex, atopy, family history of asthma, and smoking habit. Fifteen of them were also studied three times a day for five days in the laboratory with flow-volume loops. Eleven showed significant PEFR rhythms at home. No single measurement from the flow-volume loop showed periodicity in as many of them but rhythms were now also detected in the other four normal subjects in some components of the loop. Fifty-six asthma patients were studied with a similar protocol of PEFR measurement and compared with the 145 rhythmic normal subjects. Mean phases of the normal and asthmatic rhythms were not significantly different with acrophases (peak of rhythm cycle) at 1557 and 1526 respectively. The mean asthmatic amplitude was, however, significantly greater at 50.9%. Nocturnal asthma, therefore, probably represents an exaggeration of a normal circadian rhythm in airway calibre. The amplitude of the PEFR rhythm is an index of bronchial lability and is thus valuable in monitoring asthma patients. An amplitude of greater than 20% should be a useful screening test for asthma.

Does sleep cause nocturnal asthma?

The effects of sleep interruption and deprivation were studied in 21 patients with nocturnal asthma. Seven patients were awakened at 0200 on three consecutive night and exercised for 15 minutes. This produced no significant improvement in the overnight fall in peak expiratory flow rate (PEFR) compared with a control night of uninterrupted sleep. In a second study in five patients PEFR was measured at two-hourly intervals to estimate the time of onset of the nocturnal fall in PEFR. On three subsequent nights they were awakened and exercised one hour before this time. This also failed to prevent a fall in PEFR by 0600. Eleven patients, who had followed a similar protocol to the second study, were kept awake until after 0300 or later, and PEFR was observed hourly. Six of them (group A) sustained their usual fall in PEFR while awake, proving that sleep was not responsible for their nocturnal asthma. Five patients (group B) showed little fall in PEFR until they were allowed to sleep, when an appreciable fall was noted on waking at 0600. When sleep deprivation was repeated in two patients in group B, however, they sustained falls in PEFR while still awake. We conclude that the circadian rhythm in PEFR is often in phase with the timing of sleep but sleep does not cause nocturnal asthma. Disruption of sleep therefore has no apparent value in the treatment of nocturnal asthma.