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Biomedical subjects

D Lamb

Publications and source records attributed to D Lamb.

At least 91 records · Page 5Linked to original sources
PubMed1990

Role of mediastinoscopy in the diagnosis of mediastinal masses.

In order to assess the diagnostic efficiency of mediastinoscopy in patients with undiagnosed mediastinal masses, a retrospective review was undertaken of the results obtained in a consecutive series of 42 patients presenting over a 5-year period. In 28 (67%) patients, a tissue diagnosis was made. Ten (24%) patients underwent a negative mediastinoscopy but were found to have significant pathology on further investigation (eight in a location outside the range of conventional mediastinoscopy). Four (10%) patients had negative findings and were confirmed to have no significant pathology on further investigation and follow-up. Overall, mediastinoscopy had a sensitivity of 74%, a specificity of 100% and an accuracy of 76%; however, for lesions within the range of mediastinoscopy, the sensitivity was 93%, the specificity 100% and the accuracy 94%. The predictive value of a negative examination was 66%. Mediastinoscopy is a valuable technique in the diagnosis of mediastinal masses but, because of the low predictive value of a negative examination, further evaluation, including thoracotomy if necessary, is still indicated if mediastinoscopy is unhelpful.

Adolescent↗
PubMed1989

Long term survival after pulmonary resection for small cell carcinoma of the lung.

A retrospective review was undertaken of the long term survival of 97 patients with histologically proved small cell carcinoma of the lung resected during the 10 years January 1977-December 1986. Twenty seven patients (28%) had stage I disease, 29 (30%) stage II, and 41 (42%) stage III. Patients with stage I and II tumours were managed by resection alone. Patients with stage III disease received adjuvant chemotherapy (cyclophosphamide, doxorubicin, and vincristine). Pneumonectomy was undertaken in 75 patients, lobectomy in 21, and wedge resection in one patient. Three patients died within 30 days of operation. The cumulative five year survival of all patients, irrespective of tumour stage, was 17%. The cumulative five year survival was 35% for patients with stage I disease, 23% for stage II, and zero for stage III. The median survival for patients with stage III tumours was 17 months. There was no significant difference in cumulative survival between patients with stage I and II disease. Cumulative survival, however, was significantly better for patients with stage I and II disease than for those with stage III disease. The data suggest that for patients with stage I and stage II disease surgery offers the prospect of long term survival.

Adult↗
PubMed1988

Assessment of the effects of age and smoking on the media of muscular pulmonary arteries.

The effects of age and smoking on the media of muscular pulmonary arteries were studied in 23 subjects without cardio-pulmonary disease. The group ranged in age from 19 to 81 years and included 12 non-smokers and 11 smokers. Twelve representative tissue blocks were taken from each subject and all cross-sectionally cut arteries were measured from histological sections using a digitizer. Medial area was measured and artery size defined as total length of internal elastic lamina. Only arteries measuring less than 1500 micron length of internal elastic lamina were studied. For all subjects, the relationship between medial area and length of internal elastic lamina was a curve, which was linearized by plotting square root of medial area against artery size. These individual linear regression equations (y = A + bx) were used to 'predict' for each subject the amount of muscle in the walls of arteries of a specific size: 500, 1000, and 1500 micron length of internal elastic lamina. Using this type of summary data it was found that neither age nor smoking affected the media. Individual (inter-subject) variation was evident in the amount of muscle present in any size of artery, particularly in the smallest arteries. In arteries measuring 500 micron length of internal elastic lamina, the amount of muscle was positively and significantly correlated with the absolute weight of the right ventricle.

Adult↗
PubMed1988

A comparison of patient survival and tumour growth kinetics in human bronchogenic carcinoma.

A series of 46 primary bronchogenic carcinomas for which thymidine labelling index (%TLI) (in all cases) and tumour doubling time (DTact) (in 13 cases) had previously been measured were followed up for 5 years and these data compared with length of post operative survival, tumour volume at operation and pathological staging. We found no correlation between reduced survival and higher tumour %TLI, indeed the reverse may be true. Larger tumours tended to have higher labelling indices considering either primary tumour volume or 'T'-category. Five year survivors had smaller tumours, tended to have T1 tumours and Stage I disease but did not have significantly lower tumour %TLIs. No relationship was found between DTact and any other parameter.

Adenocarcinoma↗
PubMed1988

Significant intimal abnormalities in muscular pulmonary arteries of patients with early obstructive lung disease.

Substantial intimal changes, unrelated to aging, were found in resected lobes or lungs of 30 smokers with early obstructive lung disease (22 men, eight women: age range 46-74 years: forced expiratory volume in one second (FEV1)% predicted range 47-119%). Intimal area was measured using a digitiser and expressed as a proportion of the area enclosed by the internal elastic lamina (IEL), correcting for constriction (intima index). Arteries were subdivided into four size (length IEL) groups. For the smallest group (less than or equal to 600 micron length IEL) the mean intima index (II600) ranged from 0.09-0.34; half the values were greater than or equal to 0.20. Intimal abnormality was unrelated to the size or site of tumour or to macroscopic emphysema, and correlated weakly with pack years. II600 values were, however, significantly correlated with factors known to be affected by smoking such as alveolar wall surface area per unit lung volume, FEV1% predicted, and FEV1/FVC (forced vital capacity); these last two factors were also significantly associated with intimal abnormality in arteries measuring 601-1200 micron length IEL.

Age Factors↗
PubMed1988

CT measurements of lung density in life can quantitate distal airspace enlargement--an essential defining feature of human emphysema.

We used a computerized microscopic image analysis system to directly measure the surface area of distal air spaces in methacrylate-embedded blocks randomly selected from inflation-fixed lobes that were resected from 45 patients as treatment of their peripheral lung tumors. In 28 of these patients, a preoperative computer tomography (CT) scan, at 6 and 10 cm below the sternal notch, was used to generate frequency histograms of CT numbers (measured as EMI units), a measure of lung density, in pixels from the lung or lobe that was subsequently resected. A similar CT number histogram was also derived from the lateral two fifths of the area of lobe/lung that was to be resected. The EMI unit that defined the lowest fifth percentile of this latter histogram correlated (n = 28, r = -0.77, p less than 0.001) with the mean value of the surface area of the walls of distal airspaces per unit lung volume (AWUV) in the five 1 mm x 1 mm microscopic fields with the lowest AWUV values, out of the 20 to 35 such fields examined in each patient. In the 34 of the 45 patients in whom we also measured volume-corrected diffusing capacity (DLCO/VA), this also correlated (n = 34, r = 0.84, p less than 0.001) with this value of AWUV, which measures the surface area of airspaces distal to the terminal bronchioles--reflecting an increase in airspace size, a defining characteristic of emphysema. However, a low DLCO/VA is nonspecific, whereas an abnormally low regional lung density is more likely to be specific for emphysema. In addition, highlighting those pixels of the CT display with low CT numbers (i.e., EMI units -500 [air] to -450, where zero = water) can locate areas of macroscopic emphysema, as shown by subsequent pathologic examination. Thus the quantitative CT scan can diagnose, quantitate, and locate mild to moderate emphysema, in humans, in life, noninvasively.

Aged↗
PubMed1987

Functional tests of spermatozoa. Sperm penetration assay.

Optimization of each step in the standard protocol of the sperm penetration assay has increased the sensitivity of the traditional assay, and this increased sensitivity has allowed us to avoid the production of false-positive results. Development and use of routine quality control methods now enable us to compare different samples from a given individual and monitor with confidence biological variation and response to medical or surgical treatment. Although our test is extremely predictive of how well a patient's specimen may do as a result of normal intercourse, artificial insemination, and human in-vitro fertilization, it must be stressed that the sperm penetration assay and the sperm capacitation index reported by our laboratory only measure the ability of a sperm to capacitate and fuse with zona-free hamster ovum. How well spermatozoa disperse the cumulus and bind to and penetrate the human zona pellucida is not measured by this test. This would be reflected by an apparent "false-positive" outcome in the sperm penetration assay. However, our data from 138 patients suggest that this occurs only on rare occasions (in 2 of the 138). The test can be used only as a supplement to a conventional semen analysis because other factors, such as motile concentration and motility characteristics, clearly are also of importance particularly in vivo. The results obtained by our laboratory using the optimized assay described herein demonstrate that this test can play an important role in the evaluation of an infertile man.

Animals↗
PubMed1986

Effects of age and smoking on intima of muscular pulmonary arteries.

The lungs of twenty three subjects, 12 non-smokers and 11 smokers, age range 19-81 years, were studied. All were free from cardiopulmonary disease. The cross sectionally cut muscular pulmonary arteries of each subject were measured in sections obtained from 12 representative tissue blocks using a digitiser. Intimal area was measured and artery size defined as total length of internal elastic lamina (IEL). Intimal abnormality was expressed in the form of an intima index calculated by dividing intimal area by the area enclosed by the IEL in its theoretically unwrinkled state. Mean intima indices were calculated for arteries in four size groups: less than or equal to 600 micron, 601-1200 micron, 1201-1800 micron and greater than 1800 micron length of IEL. For all subjects intimal abnormality was most severe in the smallest muscular pulmonary arteries; values for mean intima indices decreased with increasing size of artery. There were no lobar differences. The amount of intimal abnormality increases with age in all sizes of artery: in the 600 micron size group this could average a 32% reduction in lumen calibre in those aged 60 or more. We were unable to detect any correlation between intimal abnormality and the subject's smoking history.

Adult↗
PubMed1985

New method for measuring intimal component of pulmonary arteries.

Current methods for assessing the intima of pulmonary arteries produce measurements of intima and artery size that are affected by the constriction or collapse of the arteries and the generally patchy distribution of intimal abnormality. Our new method measures intimal area and defines artery size as the total length of the internal elastic lamina; these measurements are unaffected by the constriction or collapse of the arteries and are easily and directly obtained from histological sections, using a light microscope with a camera lucida attachment in conjunction with a microcomputer linked to a digitising board. The measurements produced are consistently repeatable. We considered that the extent of intimal change in a pulmonary artery was most readily understood when expressed not as an area measurement but in the form of an "intima index", in which intimal area is calculated as a proportion of the area enclosed by the internal elastic lamina in its theoretically unwrinkled state. Values for intima index range from greater than 0 to less than or equal to 1, indicating minimal through to total occlusion of the artery lumen. Although values for the intima index increased as artery size decreased in the subjects studied, there was no consistent overall correlation between intima index and artery size for different subjects. We therefore concluded that subjects should be compared by calculating mean intima indexes for arteries subdivided into groups according to size.

Adult↗
PubMed1985

Method for maximising measurements of muscular pulmonary arteries.

Using a digitiser for assessing the media and intima of muscular pulmonary arteries, we have previously shown that the most sensible measurements are those of medial and intimal area and that artery size should be defined in terms of the total length of internal elastic lamina. These measurements do not vary with the collapse or constriction of the artery. A cross sectional cut and a well defined internal elastic lamina are essential for measurement using our technique. This study explores methods for obtaining the above three measurements for cross sectionally cut arteries with an ill defined internal elastic lamina, with a view to increasing the number of arteries measured. The methods were tested on three subjects, using arteries for which the true values of the three variables were known. Acceptable estimates of medial and intimal area could be obtained by simply delineating the boundaries of the intima and media and ignoring the crinkles in the elastic laminae. It was also found that muscular pulmonary arteries may not be uniformly collapsed or constricted round the circumference of their walls and that the overall degree of collapse or constriction seemed to be affected by the size of the artery. An acceptable estimate of the total length of an internal elastic lamina was most readily obtained by multiplying the length of the boundary between intima and media by a crinkle factor based on an optical assessment of the amount of crinkling in that internal elastic lamina.

Aged↗