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Biomedical subjects

D J Ross

Publications and source records attributed to D J Ross.

At least 37 records · Page 2Linked to original sources
PubMed1997

Assessment of postural differences in regional pulmonary perfusion in man by single-photon emission computerized tomography.

1. With the advent of single-photon emission computerized tomography, controversy has arisen with regard to the significance of gravitational influences on regional pulmonary perfusion (Qr) in the supine versus prone postures. We investigated the dorsal-ventral distributions of Qr in prone (n = 5) and supine (n = 5) normal subjects, as assessed by single-photon emission computerized tomography after intravenous injection of technetium-99m-labelled macroaggregated albumin at end-tidal expiration. Reconstructed serial (one pixel thickness) coronal sections were traced on a computer screen, to yield the encompassed radioactive counts and number of pixels per each image. Coronal section data (expressed as mean radioactive counts/pixel) were expressed in a 'profile' and normalized to the maximum coronal section of each lung (% maximum). 2. Coefficients of variation and linear regression slopes for the prone versus supine profiles for left and right lungs were not statistically different (unpaired Student's t-test). The coronal section with maximum Qr was identified in the more dependent lung regions and, hence, affected by gravity. 3. We conclude that, in contrast to previous canine models, which have suggested postural differences in dorsal-ventral perfusion gradients, in normal man gravity primarily determines the non-dependent to dependent distribution of Qr. We speculate that interspecies differences in physiology may be teleological and related to the different perfusion demands of the quadruped compared with upright man.

Adult↗
PubMed1997

SWORD '96: surveillance of work-related and occupational respiratory disease in the UK.

Chest and occupational physicians who report to the SWORD surveillance scheme are estimated to have seen some 3,300 new cases of work-related respiratory disease in 1996. This total has regained the level recorded prior to a low in 1995, probably because of improved chest physician participation and the introduction of a sampling system for occupational physicians. Trends in disease incidence have remained fairly constant with some changes only in pneumoconiosis and inhalation accidents. It is of concern that there has been no evidence of a decrease in frequency of occupational asthma or in any of the incriminated agents since the scheme began in 1989. Comparison with other sources of data shows that, for asthma, SWORD records a relatively high frequency in women, a substantial proportion of whom do not appear to receive compensation. For mesothelioma, rates based on death certificates continue for understandable reasons to run at about twice the level reported to SWORD or as reflected by successful claims to the DSS for industrial injuries benefit. The SWORD programme is now one of six clinically-based reporting schemes which, by the end of 1997, are planned to cover all types of occupational disease in the UK.

Adult↗
PubMed1997

"Refractoriness" of airflow obstruction associated with isolated lymphocytic bronchiolitis/bronchitis in pulmonary allografts.

The clinical significance of an isolated "lymphocytic bronchiolitis/bronchitis" (grade B) as detected in transbronchoscopic biopsy specimens (TBB) is unclear. We therefore have reviewed the spirometric responses associated with isolated grade B diagnoses and contrasted them with episodes of "acute cellular rejection" (grade A); the latter are manifested by "perivascular lymphocytic infiltration." Because lymphocytic bronchiolitis/ bronchitis is considered a nonspecific histologic pattern that may be observed with either allograft rejection or respiratory infections, episodes were analyzed with respect to the presence (grade B [+] CMV) or absence (grade B [-] CMV) of cytomegalovirus infection. The maximum forced expiratory volume in 1 second (FEV1) during the preceding 3 months was used as a baseline for computing percent change in FEV1 coincident with transbronchoscopic biopsies (delta %FEV1 PRE) and maximum values obtained during the 3 months subsequent to specific therapies (delta %FEV1 POST). All episodes of acute cellular rejection (grades A1 to 4) and symptomatic lymphocytic bronchiolitis/bronchitis (grade B) were treated with "pulsed-dose" methylprednisolone, whereas intravenous ganciclovir was administered to patients at risk for recrudescence of cytomegalovirus. Between March 1, 1989, and September 1, 1995, 366 TBB procedures were performed for clinical indications in 57 lung transplant recipients. Histologic diagnoses with acceptable serial spirometric values included grade A1 (n = 9), grade A2 (n = 27), grade A3 (n = 2), grade B(-)CMV (n = 25) and grade B(+)CMV (n = 9). The delta %FEV1 PRE coincident with TBB were not statistically different for the different histologic groups. For grade A1, delta %FEV1 PRE was -14.6% +/- 5.2% (X +/- SEM); A2, -7.6% +/- 1.8%; B(-)CMV, -14.8% +/- 3.9%; and B(+)CMV, -14.8% +/- 2.3%. After treatment, the delta %FEV1 POST, relative to baseline values, were for grade A1, -8.8% +/- 7.1%, A2, +0.26% +/- 2.6%; B(-)CMV, -12.0% +/- 3.8%; and B(+)CMV, -6.2% +/- 2.8%. The delta %FEV1 POST values after pulsed methylprednisolone were significantly greater for histologic grade A2 than grade B(-)CMV (unpaired Student's t test, P < 0.01; 95% confidence interval for the difference of means: 3.34% to 21.2%). Grade A2 rejection was associated with spirometric improvement to within 10% of baseline values in 52% of episodes; whereas with grade B(-)CMV, this salutary response was observed in only 32% of episodes. Bronchiolitis obliterans syndrome stage 1b developed in 13 of 20 (65%) recipients, approximately 7.9 +/- 3.4 months after detection of histologic grade B and 21.2 +/- 9.5 months after transplantation. We conclude that the relative "refractoriness" of histologic grade B most likely reflects a continuum of bronchiolitis obliterans after lung transplantation and, hence, may warrant different immunosuppressive strategies. Furthermore, spirometric decrement associated with acute cellular rejection (grade A) may be ameliorated, but often not completely reversed, after pulsed methylprednisolone. We speculate that surveillance TBB may prove rewarding by enabling an earlier detection of these histologic diagnoses before the development of physiologic impairment.

Airway Obstruction↗
PubMed1996

Asthma following inhalation accidents reported to the SWORD Project. Surveillance of Work-related and Occupational Respiratory Disease.

A follow-up study in 1994 of all inhalation accidents reported to the Surveillance of Work-related and Occupational Respiratory Disease project (SWORD) found that in 11 (3%) of 406 cases reported by occupational physicians and in 39 (18%) of 217 cases reported by chest physicians the patients had developed asthma-like symptoms. In a further follow-up in 1995, physicians who had reported these 50 cases were asked whether they still considered that their patients had developed asthma as consequence of the inhalation accident and further details were sought. Of the 11 cases reported by occupational physicians, seven were considered due to the inhalation accident, compared with 27 of 39 from chest physicians. The majority (88%) of diagnoses were supported by respiratory function tests. Accidents with prescribed sensitizing agents more frequently resulted in asthma than those with other agents. Of 34 cases, only six had recovered when last seen, so it was unlikely to have been due to transient bronchial hyperreactivity. The positive predictive value of respiratory symptoms increased with the number and duration of symptoms but was low for occupational physicians.

Administration, Inhalation↗
PubMed1996

Diabetes and trigger finger.

Trigger finger is a stenosing tenovaginitis in which there is a constriction of the annular sheath associated with a nodule in the digital flexor tendon. Clinically this can present as triggering or snapping of the nodule as it passes through the tight constricting tendon sheath. Although many triggering fingers settle spontaneously, and others respond to local anesthetic and steroid injection, others require surgical decompression. The association between diabetes and trigger finger, although not widely known, has been described and forms part of the "diabetic hand syndrome". We studied 100 adult patients in the group that required surgery. Eighteen of the 100 patients were diabetic with six insulin dependent diabetics (IDDM) and 12 non-insulin dependent diabetics (NIDDM). In the current climate of day case surgery this has significant implications both for the management of known diabetics as well as the preoperative detection of those with the condition.

Diabetes Mellitus, Type 1↗
PubMed1996

SWORD '95: surveillance of work-related and occupational respiratory disease in the UK.

An estimated 2,741 new cases of occupational respiratory diseases were reported by chest and occupational physicians in 1995. Total cases reported by 'core' chest physicians and occupational physicians have risen but cases reported by 'sample' physicians have fallen by 32%, reducing the estimated total overall by approximately 16% from 1994. Steps are being taken to reverse this downward trend. Occupational asthma remains the single most frequently reported disease of which more than two thirds of cases were attributed to sensitization. Non-malignant pleural disease was the next most frequently reported, with pleural plaques predominating in 71% of cases. In a study of a selected sample of 158 cases of non-malignant pleural disease, 81 (51%) were seen for medico-legal reasons; of the remainder 13% had signs or symptoms ascribed to the disease.

Adult↗
PubMed1996

Delayed development of obliterative bronchiolitis syndrome with OKT3 after unilateral lung transplantation. A plea for multicenter immunosuppressive trials.

There is no consensus regarding the optimal induction immunosuppression regimen after lung transplantation (LT). In addition to the potential benefit of a reduced incidence of early acute allograft rejection, cytolytic induction immunosuppression may impact on long-term allograft function. We retrospectively assessed our incidence of obliterative bronchiolitis syndrome (OBS) stages Ia and IIa in LT survivors given two different cytolytic induction immunosuppression regimens: (between March 1989 and October 1990) OKT3 (5 mg/d)x10 to 14 days (n=11) vs (between November 1990 and April 1993) Minnesota antilymphocyte globulin (MALG) (10 to 15 mg/kgdx5 to 7 days. Cyclosporine (CSA) (whole blood polyclonal assay=600 to 800 ng/mL), azathioprine (1 to 2 mg/kg/d), and maintenance prednisone (0.2 mg/kg/d) were similar. Surveillance spirometry was performed monthly, in accordance with accepted American Thoracic Society criteria. Fiberoptic bronchoscopy with transbronchial biopsies (TBBs) were performed for clinical indications. Surveillance TBBs were not performed during the era of this study. As defined by the ISHLT "Working Formulation for the Standardization of Nomenclature and for Clinical Staging of Chronic Dysfunction in Lung Allografts," latencies to development of OBS stages Ia and IIa were determined by Kaplan-Meir analysis. Stepwise regression (Cox proportional hazards model) was performed for the variables: cytolytic induction regimen, episodes cytomegalovirus (CMV) pneumonitis, episodes CMV infection, serologic CMV donor (+): recipient (-) mismatch, prior pregnancy, HLA (A,B,DR +/- DQ) mismatches, episodes greater than grade A1 acute cellular rejection (ACR). We found that the OKT3 cohort experienced longer latencies for OBS stages Ia and IIa. Latencies to OBS stages Ia for OKT3 ve MALG were 962 +/- 65 vs 354 +/- 85 days (X +/- SEM) respectively. Brookmeyer-Crowley 95% confidence intervals for median latencies were 744 to 1,180 vs 266 to 510 days for OKT3 vs MALG, respectively. The Cox model was significant only for the variable of the induction cytolytic immunosuppression regimen (p=0.0015). By physiologic criteria, a longer course of OKT3 appeared superior to the short-course MALG protocol in delaying chronic lung allograft dysfunction. These effects may be related either to inherent differences in the antilymphocyte preparations or, alternatively, the difference in duration of treatment between groups. Surveillance TBB and treatment of detected occult ACR may serve to negate the observed differences in latencies for OBS.

Acute Disease↗
PubMed1995

Isogravitational heterogeneity of perfusion after unilateral lung transplantation.

1. Single-photon emission computerized tomography in both an intact canine model and man has demonstrated an aspect of pulmonary perfusion to be independent of gravitational forces. 2. Using technetium 99m-labelled macroaggregated albumin single-photon emission computerized tomographic imaging, we investigated normal human subjects (n = 5), stable unilateral lung transplant recipients (n = 6) and transplant recipients with chronic allograft dysfunction related to obliterative bronchiolitis (n = 5). 3. In coronal isogravitational sections, a 1 x 1 x N pixel strip (medial to lateral) was constructed through the 'core' pixel of maximal radioactive counts. The counts were measured for the 'core' pixel and at two mid-points (medial and lateral) between the core pixel and the lung edges. Coefficients of variation were computed for each isogravitational strip and compared between groups. Fractional whole-lung perfusion was determined for left versus right lungs of normal subjects and allograft versus native lungs of transplant recipients. 4. Using these indices, 'isogravitational heterogeneity' (i.e. increased 'core' versus peripheral perfusion) was observed in allografts and native diseased lungs after unilateral transplantation. Despite significantly increased fractional whole-lung perfusion directed to the allografts (84.8% +/- 3.0% and 75.8% + 12.1% for stable unilateral lung transplant recipients and patients with obliterative bronchiolitis respectively) compared with normal lungs (50.2% +/- 1.2% and 49.8% +/- 1.2% for left and right respectively), 'isogravitational flow heterogeneity' (i.e. increased 'core' versus peripheral perfusion) was preserved after transplantation. 5. These findings suggest that 'isogravitational heterogeneity' was maintained despite increased unilateral pulmonary perfusion and the presumed increase in pulmonary capillary recruitment and/or distension.

Adult↗
PubMed1995

SWORD '94: surveillance of work-related and occupational respiratory disease in the UK.

Chest and occupational physicians participating in SWORD are estimated to have seen some 3300 cases of work-related respiratory disease in 1994, similar to the totals for 1992-1993. Occupational asthma was the single most frequent diagnosis (941 cases), but asbestos exposure was considered the cause in 1529 cases of diseases of long latency. Large-scale follow-up studies showed (i) that most patients with occupational asthma failed to recover and that half had left their employer, and (ii) that many patients had long-term respiratory illness including asthma following inhalation accidents. Over the six years of the scheme there have been slight changes in attributed agents for occupational asthma and in the frequency of various diagnoses; for example, there has been a gradual reduction in reports of pneumoconiosis. A decline with birth cohort in the proportion of mesotheliomas in men employed in shipyards is shown, with some evidence of a compensatory trend in construction trades.

Adult↗
PubMed1995

Bronchiolitis obliterans in single-lung transplant recipients.

The presentation and clinical course of bronchiolitis obliterans (BO) in single-lung transplant (SLT) recipients has thus far not been well described. We retrospectively analyzed the serial spirometry of 15 SLT patients with BO. All the patients fulfilled the criteria for BO syndrome, and 11 of the 15 had histologically documented BO. Based on serial FEV1 analysis, we identified three patterns of presentation and progression of BO. The first pattern (n = 6) was characterized by a rapid onset and a relentless progressive course; the second pattern (n = 5) was characterized by a similar rapid onset and initial rapid decline, but was followed by stabilization in lung function; the third pattern (n = 4) was characterized by an insidious onset and course. In all patients, a permanent reduction in the mean forced expiratory flow during the middle half of the forced vital capacity appeared to be an early sensitive index for the development of BO. An appreciation of these different modes of presentation and progression of BO is potentially important in the assessment of prognosis and management of the SLT recipient.

Adult↗
PubMed1994

SWORD '93. Surveillance of work-related and occupational respiratory disease in the UK.

Some 3500 new cases of occupational respiratory disease are estimated to have been seen annually by SWORD participants in 1992 and 1993 with little important difference between the two years. As the number of new cases recognized and reported by chest physicians is close to complete, the estimated incidence is essentially correct. The pattern of disease which clearly emerges shows that at least half is attributable to asbestos exposure, despite the fact that lung cancer from this cause may be under-reported. Benign pleural disease comprises a large proportion of the cases, the long-term implications of which are unknown. Almost 40% of the cases reported are of occupational asthma or inhalation accidents, both due to a very large number of different agents and affecting many and varied occupations. These cases are preventable providing their occupational aetiology is recognized and appropriate measures of control are intensified.

Aged↗
PubMed1994

Utility of inhaled pentamidine prophylaxis in lung transplant recipients.

The incidence of Pneumocystis carinii pneumonia (PCP) has been shown to be high posttransplantation in the absence of prophylaxis. For this reason, lung transplant recipients routinely receive prophylaxis. We report on our results using aerosolized pentamidine prophylaxis in nine patients post-lung transplantation (eight single lung transplants, one double). The patients received monthly treatments of 300 mg of aerosolized pentamidine for a mean of 10.6 months (range, 4 to 21 months). Patients were routinely monitored with serial pulmonary function studies and bronchoscopy as clinically indicated. Two of the patients experienced bronchospasm in response to the therapy. None of the patients experienced any episodes of PCP during the period of inhaled pentamidine prophylaxis. Inhaled pentamidine is a safe and effective form of PCP prophylaxis and may be used instead of sulfamethoxazole-trimethoprim in patients who have a sulfa allergy or other untoward sulfa side effects.

Administration, Inhalation↗
PubMed1993

Hemodynamic responses to exercise after lung transplantation.

A reduced exercise tolerance, maximum oxygen uptake (VO2max), and anaerobic threshold have been reported after lung transplantation (LT). We prospectively assessed the hemodynamic responses to incremental cycle ergometry before and after LT in eight recipients. All recipients underwent a 6-week formal exercise training program. The VO2max increased after versus before LT (13.4 +/- 0.8 vs 9.2 +/- 0.8 ml/min/kg) (p < 0.01). No transition thresholds by analysis of arterial standard bicarbonate were discerned before LT, while the thresholds after LT were abnormally low (VO2 = 9.4 +/- 0.6 ml/min/kg or 35 +/- 3 percent of predicted maximum VO2). An early rise in arterial lactate was similarly observed after LT. Maximum stroke volume index increased in six of seven patients after versus before LT (51 +/- 4 vs 37 +/- 2 ml/beat/m2) (p < 0.05). Three patients demonstrated an increased mean pulmonary arterial pressure at rest, while pressures during exercise were elevated in six. Pulmonary vascular resistance was mildly elevated after LT but decreased appropriately during incremental exercise and was associated with normal cardiac output responses. We conclude that pulmonary vascular abnormalities occurred during hemodynamic exercise testing in the majority of LT recipients; however, exercise limitation was primarily attributed to cardiovascular limitation or to deconditioning in five of the recipients. In the remaining three, the exercise study was considered to be submaximal by virtue of low peak heart rates. A persistent state of deconditioning may have important implications with respect to exercise training regimens after LT.

Adult↗
PubMed1993

Regional distribution of lung perfusion and ventilation at rest and during steady-state exercise after unilateral lung transplantation.

Cardiopulmonary exercise testing has previously demonstrated a reduced maximum oxygen uptake and anaerobic threshold, as well as abnormal wasted ventilation fraction and gas exchange after unilateral lung transplantation. To further explain the mechanisms of these abnormalities, we assessed the regional distribution of pulmonary blood flow and ventilation at rest and during steady-state exercise in nine recipients of unilateral lung transplants. Krypton-81 (81mKr) aerosol and technetium-99m (99mTc) were utilized to assess lung ventilation (V) and perfusion (Q), respectively. The digitalized images were trisected to analyze apical, mid-, and basilar lung perfusion and ventilation in both the transplanted and native lung, both at rest and steady-state upright exercise. Results were compared with previously reported data obtained in normal subjects in our laboratory using the identical technique. At rest, 75 +/- 13 percent of perfusion was directed to the transplanted lung; however, the corresponding fractional ventilation was only 67 +/- 14 percent. During exercise, there was no significant change in fractional perfusion or ventilation. Resting apical perfusion in the transplanted lung was higher than normal in four patients and comparable to normal in five patients. In contrast to the augmentation of apical perfusion observed in normal subjects during upright exercise, none of our patients increased the regional perfusion to the apices during exercise in either transplanted or native lungs. These unexpected responses suggest either more maximal allograft apical recruitment at rest due to the increased allograft perfusion or an abnormality in the apical pulmonary vasculature after transplantation. Furthermore, the relative mismatch in ventilation and perfusion in transplanted and native lungs suggests regions of high V/Q in the native, and low V/Q in the transplanted lung. This mismatch is most pronounced in recipients of single lung transplants for pulmonary vascular disease.

Adult↗
PubMed1991

Ulcerative tracheobronchitis after lung transplantation. A new form of invasive aspergillosis.

Invasive aspergillosis is frequently a fatal disease in the setting of immunosuppression, including organ transplant recipients. The fungus usually affects lung parenchyma and may disseminate from there. We have recently noted tracheobronchitis in six patients with heart-lung and lung transplants, three of whom had deep mucosal ulceration and histologic evidence of invasive aspergillosis. This apparently new form of invasive disease is initially limited to the anastomosis site and large airways. Ulceration, necrosis, cartilage invasion, and formation of a pseudomembrane are the pathologic features. In two patients subsequent disseminated aspergillosis occurred with a fatal outcome. In the two single-lung recipients, disease was limited to the transplanted side emphasizing the importance of abnormal local defense mechanisms in the airways of lung transplant recipients. Routine bronchoscopic examination of the airways is important in early detection of this complication. Oral therapy with the new, antifungal agent itraconazole was successful in five of the six patients, with fatal relapse in one. A classification of the various forms of saprophytic, allergic, and invasive forms of aspergillus tracheobronchitis, to include this new entity, is proposed.

Adult↗