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Biomedical subjects

J P Lavender

Publications and source records attributed to J P Lavender.

At least 19 recordsLinked to original sources
PubMed1992

Value of scintigraphic localization of obscure gastrointestinal bleeding.

A total of 51 technetium-99m (99mTc)-labelled autologous red cell (LRC) scans performed on 49 patients for the localization of obscure gastrointestinal bleeding over a 5-year period was reviewed. The sensitivity for LRC scanning was 72.7% with a positive predictive value of 84.2%. Forty patients underwent both LRC scanning and visceral angiography during the same admission; angiography had a sensitivity of 38.9% compared with 66.7% for LRC scanning and the positive predictive values were 77.8% and 85.7%, respectively. Overall, the site of bleeding was located in 22 (45%) of 49 patients, but LRC scanning alone was successful in identifying the lesion in 16 (33%) cases. In patients who continue to bleed to the point of requiring operation, a combination of scintigraphy and angiography will localize a source in 70% of patients.

Aged↗
PubMed1979

A rabbit model to study the biokinetics of radiopharmaceuticals in bone.

A technique is described using the rabbit as the 'animal model' to measure the rate of extraction of the bone-seeking agent, technetium labelled ethane-1-hydroxy-1, 1-diphosphonate (99Tcm-EHDP) following constant-rate infusion into the femoral nutrient artery. The extraction is shown to be approximately linear for a period of 60 min. Washout of the tracer from bone was followed for a further 60 min period and graphical analysis shows that each curve could be resolved into two distinct exponential functions. The 2-h residue of 99Tcm-EHDP in bone has been examined and is found to be dependent upon its route of administration. A high residue (43.7 +/- 5.1%) results when the infusate is delivered directly into the nutrient artery and the single muscular branch is tied off. Retrograde infusion via the femoral artery results in a lower residue (7.8 +/- 2.3%). The close correlation of these results in the rabbit with our previous findings in the dog suggested that the rabbit model described can be used to study the kinetics of other radiopharmaceuticals during their passage through bone.

Animals↗
PubMed1979

Pneumatosis coli in adult acute myeloid leukaemia.

Three cases of pneumatosis coli (PC) in adult patients with acute myeloid leukaemia seen over the last five years in Hammersmith Hospital are reported. Although definite conclusions are impossible, we suggest that that pneumatosis could be due to damage to the bowel mucosa as a result of the disease or the treatment. The literature is reviewed and discussed in an inconclusive attempt to discover the source of the gas.

Adolescent↗
PubMed1979

Sacro-iliac joint scanning with technetium-99 diphosphonate.

Quantitative sacro-iliac (SI) joint scanning with methylene diphosphonate labelled with technetium-99 (99TcMDP) was performed in 25 control patients, in 16 patients with definite ankylosing spondylitis, in 23 patients with mechanical low back pain, and in 12 patients with seronegative arthritis. The mean radio-isotope index in the control group was 1.2 +/- 0.15. The highest value was 1.5. Values in excess of 1.5 were seen in patients with clinically active ankylosing spondylitis but not those with inactive disease. Three of the 12 seronegative arthritis patients (without clinical or radiological evidence of sacro-iliitis) had elevated values: all of these were positive for HL-A B27. An important finding was that six of the 23 patients with mechanical or non-specific low back pain had values above 1.5, unassociated with B27. These data emphasize the need for caution in the interpretation of abnormal sacro-iliac scans. Radio-isotope bone scanning can provide a qualitative and quantitative assessment of inflammatory activity in joints with minimal radiation exposure. Various authors have shown its value in providing early evidence of sacro-iliitis (Russell et al., 1975; Namey et al., 1977). In this study, methylene diphosphonate labelled with technetium-99 (99TcMMDP) has been used to produce quantitative sacro-iliac scans in order to evaluate sacro-iliac disease in four groups of patients presenting with or without low back pain.

Arthritis↗
PubMed1978

A technique for measuring the accumulation of 99 Tcm stannous-ethane-1-hydroxy-1, 1-diphosphonate in the canine tibia.

An experimental technique is described to measure the accumulation of 99Tcm-stannous-ethane-1-hydroxy-1, 1-diphosphonate (99Tcm-EHDP) in the canine tibia. The method involves infusion at a constant rate of known amounts of 99Tcm-EHDP into the nutrient artery supplying the tibial bone. The accumulation of the diphosphonate in bone is measured by an external sodium iodide, Nal (T1), scintillation detector. Results are presented showing that for small amounts of 99Tcm-EHDP (0.004-0.300 mg per hour) the accumulation is a nearly linear function with time for 60 minutes, after which the uptake may become variable with either a plateau formation or considerable fluctuation of activity.

Animals↗
PubMed1978

81mKr ventilation and 99mTc perfusion scans in chest disease: comparison with standard radiographs.

In 75 patients with various pulmonary disorders, ventilation and perfusion scans were obtained in multiple views with the 81mKr/99mTc technique and compared with an evaluation of regional ventilation and perfusion derived from the standard chest radiograph. In emphysema, the chest film correlated poorly with ventilation-perfusion scans, showing a trend to underestimate the functional impairment. In chronic bronchitis and asthma, large segmental defects observed on both ventilation and perfusion scans were associated with a normal chest radiograph. Typical findings in pulmonary embolism were segmental defects on perfusion scan with normal ventilation scan and clear lung fields on the chest film. In chronic left heart disease, plain films were inaccurate in predicting alteration of the base-to-apex perfusion gradient observed on the scan.

Airway Obstruction↗
PubMed1977

Kinetics of indium-III labelled lymphocytes in normal subjects and patients with Hodgkin's disease.

The distribution in the body and the circulation in the blood of autologous lymphocytes labelled with indium-III were studied in two normal subjects and two patients with Hodgkin's disease. Four hours after injection radioactivity was identified in the spleen, liver, and bone marrow. Radioactivity, followed by imaging and whole body scanning, began to appear in the lymph nodes four to 18 hours after injection, and some, though not all, lymph node groups in the body could be readily visualised. There were no differences between the normal subjects and the patients with Hodgkin's disease. The pattern of clearance of radioactivity from the blood was consistent with a normal circulation between blood and lymphoid tissues of the labelled lymphocytes. Since indium-111 stays firmly attached to the cell, it seems an ideal label for studying lymphocyte kinetics, and the use of this technique may have further clinical application.

Hodgkin Disease↗
PubMed1977

A comparison of radiography and radioisotope scanning in the detection of Paget's disease and in the assessment of response to human calcitonin.

In eight patients with symptomatic Paget's disease, radiographs and radioisotope bone scans have been compared before treatment by high dose synthetic human calcitonin (CIBA 47175-Ba) and three months and 12 months later. In six patients quantitative radioisotope scans allowed calculation of relative radioactivity in normal bone, Paget's disease and bone adjacent to osteoarthritic joints. Comparison of radiographs and scans showed 69 sites diagnosed as Paget's disease on both examinations; nine sites showed radiographic changes of Paget's disease but had negative radioisotope scans and two sites were abnormal on the scan but radiologically normal. One of these two reverted towards normal during treatment with calcitonin. Comparison of analogue scans done at three months and 12 months with initial scans showed diminished uptake in Paget's disease compared with normal bone, and quantitation showed this was due to decreased absolute uptake in Paget's disease and a slight increase in normal bone. Osteoarthritic bone showed no significant response to calcitonin.

Aged↗
PubMed1977

Indium-111-labeled autologous leukocytes in man.

Autologous leukocytes have been isolated, labeled with indium-111, and administered to 15 patients suspected of inflammatory disease. The stability of the label has been demonstrated and the in vivo kinetics and distribution of the labeled cells studied. The distribution is influenced by the type and viability of the cells separated by three different techniques. Generally, there was initial accumulation of radioactivity in the lungs; approximately half of this cleared in 15 min and the remainder slowly. Twenty-five to 50 percent of the radioactivity subsequently distributed in the spleen, liver, and bone marrow, and these did not show significant change with time up to 48 hr post injection. The In-111 radioactivity administered as labeled leukocytes free from erythrocytes cleared from the circulating blood with a half-time of 7.5 hr. In three of 15 patients, the suspicion of inflammatory disease could not be confirmed, and in these a normal distribution of radioactivity was observed. In the remaining 12 patients, focal accumulation of radioactivity was detectable within 4 to 24 hr after administration, and subsequent confirmation of sepsis was obtained. From three such patients, samples of abscesses were recovered which showed markedly higher radioactivity than that in the same weight of blood.

Abscess↗
PubMed1976

Indium-111-labelled leucocytes for localisation of abscesses.

Leucocytes from eight patients who were thought to have an abscess were labelled with indium-111 and reintroduced into the circulation. The distribution of radioactivity was followed by whole-body scanning and imaging with a gamma camera. Focal accumulation of radioactivity were observed in the lesion in the three patients with abscesses, in the lungs of a boy with bacterial endocarditis, in the knee of a woman with rheumatoid arthritis, and at the site of intramuscular injections in another patient. The use of radiolabelled cells for the detection of focal pathological processes would seem to be an important addition to conventional diagnostic methods.

Abscess↗
PubMed1976

Tissue and hepatic subcellular distribution of liposomes containing bleomycin after intravenous administration to patients with neoplasms.

1. Liposomes containing 111In-labelled bleomycin were injected intravenously into two patients. One patient had a hepatoma and the other had secondary adenocarcinomatous deposits in the liver. 2. The tissue distribution of 111In was determined by whole-body scanning and by measurement of the radioactivity in organs at autopsy. 3. Scans in vivo and post-mortem measurement of radioactivity indicated that liposomes accumulate predominantly in the liver, but that there is no selective uptake of liposomes by the malignant tissue. 4. The subcellular distribution of radioactivity in the liver was measured 90 min after injection by fractionation of percutaneous liver biopsies on sucrose density gradients. 5. Radioactivity within the liver was concentrated in lysosomes. 6. Electron microscopy of tissue obtained before the administration of liposomes revealed particles morphologically indistinguishable from liposomes in hepatoma cells and hepatocytes.

Adenocarcinoma↗
PubMed1976

Continuous imaging of regional myocardial blood flow in dogs using krypton-81m.

The unique physical properties of the freely diffusible gas krypton-81 m allowed continuous imaging of regional myocardial blood flow in dogs when infused into the aortic root. Regional changes in myocardial perfusion related to transient coronary artery occlusion were demonstrated both as high resolution gamma camera images and as a quantitative strip chart record.

Animals↗
PubMed1976

Preservation of normal cortical vasculature in ischaemic renal failure in the dog.

Ischaemic renal failure in the dog was studied by clamping one renal artery for 2 hr in 18 animals. Total renal blood flow was measured for 3 hr after this and only reduced by about 30%. Fine detail renal angiography showed a normal cortical perfusion pattern. Urine flow rates and creatinine clearances from these kidneys, however, were found to be grossly impaired over this period. Seven days later the angiogram of the oliguric kidney remained normal. Two-hour unilateral renal ischaemia in the dog leads to a form of acute renal failure with a striking disparity between glomerular perfusion and clearance, arguing agains a primary circulatory defect.

Acute Kidney Injury↗
PubMed1976

A comparison of clinical results in brain scanning using germanium semiconductor detectors and sodium iodide detectors.

A comparison is presented of the image quality obtained with a 70 mm Ge(Li) detector scanner and with routine techniques based on NaI (Tl) detectors. One hundred and sixty-five pairs of brain scans have been examined for which the patients have been scanned with both Ge(Li) and NaI (Tl) detectors. It is concluded that no major difficulties exist in introducing Ge(Li) scanners and that while a comparison of scans from different instruments is difficult there is evidence that improved diagnostic information may be obtained from scanners with Ge(Li) detectors.

Brain Diseases↗
PubMed1975

Indium (111In)-labelled bleomycin for the detection of intracranial lesions.

Brain scans with 99mTc pertechnetate were compared with scans made after administration of 111Indium bleomycin in 38 patients scanned on 41 occasions. They gave similar results in 34 pairs of examinations, including cases in which both failed to detect the tumour. In seven cases, the two agents differed. In two of these bleomycin distinguished residual tumour from the effects of craniotomy more clearly than did pertechnetate; in three bleomycin apparently detected tumour not seen with pertechnetate, and in two the differences may have been due to technical factors, or are unexplained.

Adult↗