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Biomedical subjects

A M Peters

Publications and source records attributed to A M Peters.

At least 163 records · Page 9Linked to original sources
PubMed1991

Extravascular chest wall technetium 99m diethylene triamine penta-acetic acid: implications for the measurement of renal function during renography.

Measurement of individual kidney glomerular filtration rate (IKGFR) from the gamma-camera technetium 99m diethylene triamine penta-acetic acid (99mTc-DTPA) renogram requires a continuous measurement of arterial activity. This is usually based on a region of interest (ROI) placed over the cardiac blood pool on the posterior view, with the assumption of negligible contamination from activity in the extravascular space of the chest wall. By injecting a small dose of technetium 99m human serum albumin (HSA) before the 99mTc-DTPA in 12 patients undergoing routine renography, the contribution of extravascular activity to the total signal recorded over the cardiac blood pool was calculated to be 11.0% (SE 2.1%) 1.5 min after DTPA injection, rising to 35.1% (SE 2.5%) at 15 min. Subtraction of the time-activity curve recorded from a ROI of the same size over the right lung generated a "pure" blood signal as shown by almost identical HSA/DTPA signal ratios recorded in blood samples taken 5 min after HSA and 15 min after DTPA and from the gamma-camera at the corresponding times. The effect of using a cardiac blood pool time-activity curve uncorrected for extravascular activity was to overestimate IKGFR by an average factor of 1.17 (SE 0.03).

Glomerular Filtration Rate↗
PubMed1991

Antenatal diagnosis of renal pelvic dilatation--the natural history of conservative management.

Seventy children with an antenatal diagnosis of unilateral renal pelvic dilatation underwent Tc 99 m DTPA diuretic renograms. There were 16 kidneys with moderate function, and 54 with good function, 31 underwent pyeloplasty, all had a renal pelvis greater than 12 mm diameter on ultrasound. Thirty nine children with good function were treated conservatively. Long term follow up has demonstrated that conservative management for PUJ dilatation with a good functioning kidney may be justified but a randomised control study is required.

Dilatation, Pathologic↗
PubMed1991

Measurement of blood flow from first-pass radionuclide angiography: influence of bolus volume.

Fractionation of cardiac output on first-pass radionuclide angiography is a recently described technique for measuring blood flow. In order to determine the influence of bolus volume, splenic blood flow (SBF) and renal blood flow (RBF) were measured from widely differing bolus volumes given in sequence over a period of a few minutes in patients undergoing routine bone scintigraphy with technetium 99m methylene diphosphonate. A bolus volume of 0.5 ml, followed by 20 ml of rapidly delivered saline "chaser", was regarded as a "gold standard" bolus. A 50 ml bolus, but not a 20 ml bolus, resulted in a significant underestimation of both SBF and RBF. Thus, using a left ventricular region of interest to generate an arterial first-pass time-activity curve, RBF from a 50 ml bolus was 58% (SEM 4%) that given by a 0.5 ml bolus, while RBF for a 20 ml bolus was 98% (8%). Corresponding values for SBF were 52% (10%) and 102% (12%). A quality control adjustment did not correct the underestimation given by the 50 ml bolus. Bolus volumes greater than 20 ml give unreliable estimates of organ blood flow by this technique.

Bone and Bones↗
PubMed1991

Bone marrow transplantation: effects of conditioning and cyclosporin prophylaxis on microvascular permeability to a small solute (technetium 99m diethylene triamine penta-acetic acid).

Microvascular permeability to small diffusible solutes has rarely been measured at a clinical level. We have developed a simple non-invasive technique for measuring the permeability surface area (PS) product, which is suitable for clinical use. We illustrate its potential value in six subjects who underwent bone marrow transplantation for chronic myeloid leukaemia. These patients received high-dose cyclosporin A (CyA) for prevention of graft versus host disease (GVHD) and sustained an easily measurable increase in microvascular permeability to technetium 99m diethyltriamine penta-acetic acid (99mTc-DTPA). This was measured as the PS product, which increased from 1.1 (SD 0.3) to 2.2 (0.4) ml/min per 100 ml tissue between baseline and treatment with CyA for prevention of GVHD (P less than 0.01). The increase broadly correlated with nephrotoxicity which was measured, from the plasma DTPA clearance, as global glomerular filtration rate (GFR). This decreased from 106 (11.1) to 49 (6.7) ml/min (P less than 0.001). These abnormalities, both in PS product and GFR, were sustained for several months, after which they tended to return towards baseline levels. We conclude firstly that this technique has a potential clinical role and secondly that endothelial abnormalities due to CyA deserve further study.

Adult↗
PubMed1991

Cytokine secretion by peripheral blood monocytes from human immunodeficiency virus-infected patients is normal.

We have measured the production of interleukin 1 (IL 1), interleukin 6 (IL 6), and tumor necrosis factor alpha (TNF alpha) by unstimulated monocytes and monocytes stimulated with lipopolysaccharide (LPS) isolated from the peripheral blood of patients infected with human immunodeficiency virus 1 (HIV-1) and healthy controls. Spontaneous and LPS-induced cytokine production were not significantly different between patients and controls. Median lipopolysaccharide-stimulated cytokine secretion for patients and controls was 1.7 and 4.3 U/ml for IL 1, 475 and 625 U/ml for IL 6, and 468 and 580 pg/ml for TNF alpha. Cytokine levels were not related to stage of disease. We conclude that in vivo HIV infection itself does not alter peripheral blood monocyte cytokine secretion.

Adolescent↗
PubMed1991

Renal haemodynamics of cyclosporin A nephrotoxicity in children with juvenile dermatomyositis.

1. Renal haemodynamics were monitored over an average period of 19 months in 17 children being treated with cyclosporin A. Sixteen had juvenile dermatomyositis and one had chronic polyneuropathy. The dose of cyclosporin A ranged from 2.3 to 8.3 mg day-1 kg-1 (median 4.1 mg day-1 kg-1). 2. Glomerular filtration rate (expressed in terms of extracellular fluid volume), renal blood flow (expressed as a fraction of cardiac output) and filtration fraction were measured by using 99mTc-labelled diethylenetriamine-penta-acetate. They were compared with the dosage and trough blood levels of cyclosporin A, and, in 15 patients receiving prednisolone in addition to cyclosporin A, with steroid dosage. 3. All 17 children had a renogram performed 6 months after starting cyclosporin A treatment. Nine of them also had a renogram before starting cyclosporin A treatment (baseline study), while 13, in addition to their renogram 6 months after starting cyclosporin A treatment, also had at least one further renogram. 4. Glomerular filtration rate/extracellular fluid volume fell slightly but significantly from 0.009 (SD 0.0013) before starting cyclosporin A treatment to 0.0085 (0.002) min-1 (P less than 0.01) 6 months after cyclosporin A treatment in the nine children who underwent a baseline study. This was accompanied by a significant (P less than 0.001) fall in filtration fraction from 0.108 (0.015) to 0.088 (0.014). However, renal blood flow/cardiac output showed no change. 5. In the 13 children studied beyond 6 months after starting cyclosporin A treatment, there was no further significant overall change in any renal haemodynamic variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Anti-platelet monoclonal antibody P256 in the diagnosis of renal transplant rejection.

Platelets labeled in vitro with In-111 have a recognized place in the diagnosis of renal transplant rejection. Following their introduction for imaging thrombi, radio-labeled anti-platelet antibodies may also have a role in the diagnosis of transplant rejection. Four of 11 patients with recently donated transplants had biopsy-proven acute rejection episodes close to the time of administration of In-111 P256 Fab' fragment, which recognizes the IIb-IIIa fibrinogen receptor on primate platelets. The transplant-to-background count rate at 3 and 24 hours after these injections were 2.2 (SE 0.14) and 2.3 (0.23), respectively, almost identical to the ratios, 2.0 (0.1) and 2.2 (0.11), recorded at the corresponding times after 19 injections of P256 Fab' that were remote in timing from rejection episodes. P256 Fab' may have value in the detection of postoperative venous thrombosis, but it has no value for the detection of transplant rejection.

Adult↗
PubMed1991

A 19-year-old man with leucocyte adhesion deficiency. In vitro and in vivo studies of leucocyte function.

We describe a male patient with leucocyte adhesion molecule deficiency (LAD) of moderate phenotype. Although diagnosis was made only 2 years before his death, the patient survived until 19 years of age. This enabled us to perform a number of novel investigation, both in vivo and in vitro, relating to his leucocyte biology. Monocytes cultured in vitro matured into morphologically normal, phagocytically capable macrophages, which were able to recognize aged 'apoptotic' neutrophils. By injection of radiolabelled autologous neutrophils we demonstrated a prolonged neutrophil half-life, but normal margination, de-margination on exercise, and splenic pooling. Neutrophil adherence in vitro to vascular endothelium was normal. Histological examination of the patient's lungs at post-mortem showed intravascular aggregation of polymorphonuclear leucocytes but a paucity of cells in the interstitium and alveolar spaces. These findings indicate that the peripheral blood leucocytosis commonly observed in these patients may be due to prolonged intravascular neutrophil survival, and suggest that CD11/18 molecules have an important role in facilitating neutrophil emigration from blood vessels at sites of inflammation.

Adult↗
PubMed1991

Fluticasone propionate in Crohn's disease.

Fluticasone propionate, a topically active corticosteroid of low systemic bioavailability after oral administration, has been used in a pilot study for the treatment of mild and moderately active Crohn's disease. Twelve patients received oral fluticasone propionate for three weeks, and the effects were monitored using the Crohn's disease activity index and by 111In granulocyte scanning, assessing inflammation from scan appearances, four day faecal excretion of radioactivity, and whole body excretion of radioactivity. All patients completed the trial. No serious side effects were reported. There was a significant fall in Crohn's disease activity index values over the three week treatment period (193 (84) v 122 (51), p less than 0.01). 111In leucocyte scan images were improved (seven patients) or unchanged (five patients). There was a significant fall in excretion of injected radioactivity calculated from whole body data (28 (21)% v 14 (0.7)%, p less than 0.05). There were no changes in plasma cortisol values, either basal or synacthen stimulated. Fluticasone propionate is a promising therapeutic agent for Crohn's disease that offers the possibility of controlling inflammation without inducing systemic corticosteroid side effects and which merits evaluation in a double blind trial versus conventional corticosteroids.

Administration, Topical↗
PubMed1991

Antenatal diagnosis of pelvic hydronephrosis: assessment of renal function and drainage as a guide to management.

The optimal management of children with antenatally diagnosed unilateral hydronephrotic kidneys is unclear. We have monitored renal function and drainage using 99mTc-DTPA renography in 77 children with such kidneys presenting at 1-14 mo of age with the aims of throwing light on the natural history of the condition and evaluating the response of the kidney to pyeloplasty. Since management was independent of the drainage criteria on renography, the opportunity also was presented to evaluate the efficacy of diuretic renography for diagnosing obstruction in these children. Follow-up ranged between 1 and 6 yr, during which renography was performed between 2 and 6 times in each patient. Thirty-nine patients were treated conservatively, while 30 patients underwent pyeloplasty at varying times after presentation. No overall significant change in function was observed either in the nonoperated children or as a result of surgery. This also applied to sub-groups of children with poor drainage. Function improved significantly, however, in a sub-group of nonoperated children who presented with impaired function in the hydronephrotic kidney. Surgery, although having no overall effect on function, significantly improved drainage. As a means of identifying obstruction, 99mTc-DTPA diuretic renography was unreliable, erroneously indicating obstruction in 24 nonoperated children in whom function of the hydronephrotic kidney never became abnormal and who could not, therefore, have been considered to have obstruction. This retrospective study underlines the importance of performing a randomized prospective study on the value of pyeloplasty in this group of children.

Diuresis↗