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S Osman

Publications and source records attributed to S Osman.

At least 73 records · Page 4Linked to original sources
PubMed1990

Labelling autologous platelets with 111In tropolonate for platelet kinetic studies: limitations imposed by thrombocytopenia.

An in vitro method of radiolabelling platelets with 111In tropolonate in plasma has been devised enabling imaging and cell kinetic studies to be performed in patients with thrombocytopenia (TP) using autologous, rather than donor, platelets. Platelets from 10 TP patients, with platelet counts ranging from 4-91 x 10(9)/l, were labelled in 50% plasma with 111In tropolonate, containing the optimum tropolone concentration of 2 x 10(-4) mol/l, at platelet concentrations ranging from 0.08-4.5 x 10(9)/ml resulting in labelling efficiencies (LE) between 51 and 86%. In 4 patients, red cells contaminated the platelets but this was corrected for by measuring the proportion of 111In on the platelets prior to injection and in the post-injection blood samples. Platelet recovery (PR), mean platelet life-span (MPLS) and platelet production rate (PPR) were calculated and splenic and hepatic images were taken. The results clearly show that useful clinical data can be obtained by this method even in patients with severe TP.

Adult↗
PubMed1988

Optimum conditions for radiolabelling human granulocytes and mixed leucocytes with 111In-tropolonate.

To determine the optimum conditions for the in vitro radiolabelling of human granulocytes with 111In-tropolonate for clinical studies, the factors which affected the amount of 111In bound to the cells, the labelling efficiency (LE), were measured. These included the tropolone concentration, labelling medium and cell concentration. The tropolone concentration was dependent on the amount of plasma in the labelling medium; with 90% ACD plasma it was 4 x 10(-4) M and with Hepes saline buffer it was 4 x 10(-5) M. Using these tropolone concentrations and a low granulocyte concentration of 1 x 10(7) ml-1, the LE in 90% ACD plasma was 29% and in buffer was 74%. However, increasing the cell concentration to 1 x 10(8) ml-1 gave a LE of 90% in buffer and plasma. The optimum conditions for clinical studies involved incubating granulocytes, or mixed leucocytes as a source of granulocytes, at a cell concentration of at least 5 x 10(7) cell/ml in 1 ml ACD plasma, pH 7-7.6 with 0.1 ml tropolone at 4.4 x 10(-3) M mixed with no more than 100 microliter 111InCl3 for 15 min at room temperature. Under these conditions more than 96% of the 111In was taken up by the granulocytes and only 3% of the 111In was released from the labelled cells during a 30 min incubation in plasma. 111In-tropolonate is therefore an efficient agent for stably radiolabelling human granulocytes in plasma for clinical studies.

Cycloheptanes↗
PubMed1988

99Tcm-HMPAO labelled leucocytes: comparison with 111In-tropolonate labelled granulocytes.

The lipophilic complex, 99Tcm-hexamethylpropyleneamine oxime (HMPAO) is an efficient leucocyte label, and labels granulocytes with more stability than mononuclear leucocytes. The recovery of 99Tcm-HMPAO granulocytes, expressed as the percentage of injected granulocyte-associated activity circulating as granulocyte-associated activity 40-45 min after injection, was 37% (S.E. 3%), similar to the recovery of 111In-labelled granulocytes isolated and labelled in plasma using tropolone. The T1/2 of 99Tcm-HMPAO labelled granulocytes in blood was 4.4 h (S.E. 0.4 h), less than that of 111In-labelled granulocytes, although when a correction was made for 99Tcm elution, it was 6.4 h. The initial biodistribution of 99Tcm-labelled leucocytes was similar to 111In-labelled granulocytes, with a rapid initial lung transit, prominent splenic activity, bone marrow activity and minimal hepatic activity, although, unlike 111In, 99Tcm activity was also seen in urine, occasionally in the gallbladder, and, from about 4 h, consistently in the colon. Bone marrow activity was particularly prominent with 99Tcm. About 6% of 99Tcm was excreted in the faeces up to 48 h after injection, and about 17% in urine up to 24 h. The time-activity curves of reticuloendothelial activity up to 24 h were broadly similar for the two labelled cell preparations, and the differences that were observed can be explained on the basis of a higher rate of 99Tcm elution. Clinical information given by the two agents was similar in 27 of 30 patients who received both. Of the three who gave different information, one received 111In-labelled granulocytes which were considered to be functionally suboptimal and two, with inflammatory bowel disease, showed different distributions of abnormal bowel activity. We conclude that with respect to granulocyte kinetics and clinical data, 99Tcm-HMPAO labelled leucocytes are comparable with 111In-tropolonate labelled granulocytes.

Colitis, Ulcerative↗
PubMed1988

The development of a clinical protocol for the radiolabelling of mixed leucocytes with 99Tcm-hexamethylpropyleneamine oxime.

To devise a protocol for the radiolabelling of mixed leucocytes with 99Tcm-hexamethylpropyleneamine oxime (99Tcm-HMPAO), the effect of HMPAO concentration, cell concentration, plasma concentration and anticoagulant on the uptake of the lipophilic complex was measured, together with the stability of the 99Tcm on the labelled cells. It was found that cell uptake was rapid, independent of HMPAO concentration over the range 20-80 micrograms ml-1, but dependent on cell and plasma concentration. Incubation of mixed leucocytes from 85 ml blood with 1 ml ACD-plasma and 4 ml 99Tcm-HMPAO containing 400 MBq 99Tcm for 10 min at room temperature gave optimum results and was used in 90 patients. The mean labelling efficiency, which was the amount of added 99Tcm incorporated by the cells, was 55% (+/- 13 S.D.), of which 77% were incorporated by the granulocytes, 17% by the mononuclear cells and 6% by the platelets and erythrocytes. During a 1 h incubation in plasma 9% (+/- 4% S.D.) of the 99Tcm were released from the labelled mixed leucocytes. This occurred predominantly from the mononuclear cells.

Clinical Protocols↗
PubMed1988

Osteomyelitis.

The use of 111In-labelled granulocyte scintigraphy is recognized as a reliable method for detecting osteomyelitis and has similar sensitivity and significantly increased specificity compared to bone scintigraphy and 67Ga studies. Recent published work using pure granulocytes labelled with 111In tropolonate to detect osteomyelitis resulted in sensitivity of 100% and specificity of 92%. 99Tcm as an alternative granulocyte label offers advantages of convenience, lower radiation dose and higher image resolution. We have scanned 20 patients with suspected osteomyelitis using autologous granulocytes labelled with 99Tcm hexamethylpropyleneamineoxime (HMPAO), 12 of whom had prosthetic joints. The scan results were correlated with clinical, radiographic, microbiological and histological findings. Sensitivity was 100% and specificity was 93% which compares favourably with results obtained using 111In-labelled granulocytes. We believe that labelled granulocyte scintigraphy is a useful investigation in the diagnosis of osteomyelitis and that 99Tcm HMPAO appears to be at least as useful as 111In as the labelling agent.

Granulocytes↗
PubMed1988

Inflammation: imaging with Tc-99m HMPAO-labeled leukocytes.

Leukocytes labeled with technetium-99m hexamethylpropyleneamine oxime (HMPAO) were used in 100 patients: 32 with suspected inflammatory bowel disease, 17 with fever of unknown origin, 21 with suspected abdominal sepsis, 20 with suspected bone sepsis, seven with bronchiectasis, and three with recent myocardial infarction. The distribution of activity in patients subsequently shown not to have inflammatory bowel disease was similar to that previously described for indium-111-labeled leukocytes. However, in this study, activity was also seen in the kidneys and bladder and occasionally the gallbladder on both early (1-3 hours) and late (24 hours) views, and in the colon in late views. Migration of Tc-99m-labeled granulocytes was seen in inflammatory disease as early as 30 minutes after injection, while normal bowel activity was not seen before 4 hours. The sensitivity of Tc99m-labeled leukocytes in the detection of inflammation was 100%, the specificity was 95%.

Colitis↗
PubMed1988

Investigations to determine the optimum conditions for radiolabelling human platelets with 99Tcm-hexamethyl propylene amine oxime (99Tcm-HM-PAO)

99Tcm-hexamethyl propylene amine oxime (99Tcm-HM-PAO) has been evaluated as an agent to radiolabel human platelets in vitro. The rate of uptake of this lipophilic complex, the effect of HM-PAO, plasma and platelet concentration were measured to determine the optimum conditions for radiolabelling platelets for short-term clinical investigations of thromboses. The complex was made according to the manufacturer's instructions and immediately added to isolated platelets in vitro. The rate of labelling was slower than for leucocytes, reaching a plateau after approximately 40 min at room temperature (RT). Increasing the temperature to 37 degrees C did not increase the labelling efficiency (LE). Addition of plasma to platelets at a cell concentration of 1 x 10(9) [corrected] ml-1 reduced the LE from 66% in saline to 52% in 20% ACD-plasma. However, increasing the platelet concentration from 5 x 10(8) to 2 x 10(9) ml-1, increased the LE from 9 to 76% for platelets labelled in 20% plasma for 30 min at RT. The in vitro stability of the 99Tcm in the labelled cells showed that 7% of the radioactivity were immediately released from the platelets and a further 13% were eluted during a 60 min incubation in plasma at 37 degrees C. It has been concluded that incubation of platelets at RT with 99Tcm-HM-PAO containing 80 micrograms ml-1 HM-PAO at a cell concentration of 1 x 10(9) ml-1 or greater, results in a high LE, with more than 85% of the 99Tcm being retained by the platelets during a 60 min incubation in plasma.

Blood Platelets↗
PubMed1987

A simple in vitro method of radiolabelling human erythrocytes in whole blood with 113mIn-tropolonate.

A simple and rapid in vitro procedure has been developed for selectively radiolabelling erythrocytes in whole blood using 113mIn-tropolonate. A maximum labelling efficiency of 97% was achieved, of which 95.5% was on the erythrocytes after only 5 min incubation of whole blood at room temperature. The optimum amount of tropolone for labelling whole blood was 10 micrograms of tropolone per ml of blood using acid-citrate dextrose (ACD) as the anticoagulant and 50 micrograms of tropolone per ml of blood using heparin. Under these optimum conditions, only 2.5% of the cell-bound 113mIn was released from the labelled cells during a 1 h in vitro incubation in cell-free plasma, irrespective of the anticoagulant used. These results suggest that 113mIn-tropolonate may prove to be a useful in vitro agent for labelling erythrocytes for short-term clinical investigations, especially at centres where 99mTc and 111In are unavailable.

Cycloheptanes↗
PubMed1987

Syphilis in women of reproductive age in Mogadishu, Somalia: serological survey.

In Mogadishu, Somalia 223 women of childbearing age, including prostitutes, were tested for serum markers for syphilis by the Venereal Disease Research Laboratory (VDRL) test and the Treponema pallidum haemagglutination assay (TPHA). Sera reactive in either of these tests were tested for IgM antibodies by solid phase haemadsorption assay (SPHA). Three per cent of sera from 67 pregnant women and none of those from 71 educated women gave positive results that were confirmed with the TPHA. In contrast, 58% of sera from 85 prostitutes were confirmed as being positive, 26% of which were SPHA positive, which indicated active syphilis. The proportion of TPHA positive sera increased with age among the prostitutes. As venereal syphilis is highly prevalent in prostitutes in Mogadishu, a strategy of intervention based on screening followed by treatment seems to be indispensable.

Adolescent↗
PubMed1987

Sexually transmitted viral infections in various population groups in Mogadishu, Somalia.

The prevalence of serum antibodies to human immunodeficiency virus (HIV), herpes simplex virus (HSV), and cytomegalovirus (CMV) and of hepatitis B virus (HBV) markers was investigated in different population groups, including prostitutes, in Mogadishu, Somalia. Hepatitis B surface antigen (HBsAg) was detected in 37% of pregnant women, 4% of neonates, 22% of educated women, and 20% of prostitutes. No significant difference between the groups was observed for HBV. In contrast to figures reported from South East Asia, the prevalence of hepatitis Be antigen (HBeAg) was 18% in prostitutes and only 3% in all other HBsAg positive subjects. The prevalence of antibodies to HSV (100%) and CMV (90%) was very high, but antibodies against HIV were not detected in any of 471 sera. As the routes of transmission for HBV and HIV infections are considered to be similar, HIV will probably spread rapidly in Somalia once this virus has been introduced into the country.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Clinical experience with 99mTc-hexamethylpropylene-amineoxime for labelling leucocytes and imaging inflammation.

Hexamethylpropylene-amineoxime (HMPAO) forms a lipid-soluble neutral complex with 99mTc which is rapidly incorporated into leucocytes in vitro. In six patients with suspected or known inflammatory disease, a "mixed" leucocyte suspension isolated from 85 ml blood anticoagulated with acid-citrate-dextrose was labelled by 99mTc-HMPAO with a mean efficiency of 47% (SE2%), of which 78% (3) was taken up by granulocytes. Activity eluted more rapidly from other cell types in vitro than from granulocytes, which remained firmly labelled. Mean initial biodistribution of the label and granulocyte recovery in blood of 32% (8) at 30-40 min showed that the granulocytes were not significantly activated during labelling. All six patients were positive for inflammatory disease, as early as 30 min in five patients and at 3 h in the sixth; they all remained positive at 20-24 h. Four patients also received 111In-labelled "pure" granulocytes. In terms of detail, the 99mTc images were comparable or superior to the 111In images.

Adult↗
PubMed1986

Erythrocyte radiolabelling: in vitro comparison of chromium, technetium, and indium in undamaged and heat damaged cells.

The stability of the commonly used red cell radio labels chromium-51, indium-(111 or 113m), and technetium-99m, within intact red cells and stroma and their distribution within the cell were compared in undamaged and heat damaged red cells in relation to the clinical use of heat damaged cells in the assessment of splenic function. Chromium-51 labelled haemoglobin both in undamaged and heat damaged cells; indium predominantly labelled haemoglobin in undamaged cells but labelled stroma in heat damaged cells, even when the cells were labelled before heating; technetium-99m predominantly labelled haemoglobin in undamaged cells but only labelled stroma in heat damaged cells if these were heated before labelling. Indium was more firmly bound by stroma prepared from heat damaged cells, and technetium-99m showed a high rate of elution both from cells and stroma, although this rate was lower for heat damaged cells.

Chromium Radioisotopes↗
PubMed1986

The importance of radiolabelling human granulocytes with 111In-tropolonate or 111In-2-mercaptopyridine-N-oxide in plasma containing acid-citrate-dextrose.

When blood cells are radiolabelled in plasma, for example with 111In-tropolonate, the plasma always contains an anticoagulant, usually acid-citrate-dextrose (ACD) or heparin. The effect of ACD and heparin on the labelling efficiency (LE) and optimum concentration of ligand required to radiolabel human granulocytes in plasma with 111In-tropolonate or 111In-2-mercaptopyridine-N-oxide (111In-merc) has been measured. The concentrations of ligand (tropolone or merc) required for maximum cell labelling in plasma containing ACD were 4 X 10(-4) M tropolone and 1 X 10(-4) M merc, whereas using plasma containing heparin, the optimum concentrations were 10-fold higher, at 4 X 10(-3) M and 1 X 10(-3) M respectively. At the optimum ligand concentrations, the LE for 1 X 10(8) granulocytes labelled in plasma containing ACD was 90% using 111In-tropolonate and 82% using 111In-merc, whereas using plasma containing heparin they were 68% and only 20%, respectively. Addition of ACD to heparinised plasma abolished the necessity for more ligand and increased the LE to the same values as those for plasma containing ACD alone. These results clearly demonstrate that to obtain a high LE using the lowest possible concentrations of tropolone or merc, the granulocytes must be labelled in plasma containing ACD.

Citric Acid↗
PubMed1984

PAC studies of 111In binding to transferrin, tropolone and acetylacetone in aqueous solutions.

Time integral and time-differential PAC measurements have been made over a wide temperature range in aqueous solutions of [111In]tropolonate and [111In]acetylacetonate. The quadrupole frequency in the latter is approximately 30% higher than that in the former and the molecular volumes derived from rotational correlation times show the expected differences. Apo-transferrin was separately added to the two 111In-chelates and the transfer of activity from chelate to transferrin followed as a function of relative molar concentrations. Very much larger molar ratios of transferrin to tropolone than of transferrin to acetylacetone were required before substantial transfer of 111In from chelate to transferrin took place. This difference in affinity for transferrin could be one significant factor in explaining the enhanced ability of [111In]tropolonate to label blood cells in the presence of plasma. The determination of PAC parameters in [111In]transferrin over a range of temperatures showed that the values of quadrupole frequency obtained depended on the number of binding sites assumed. For only one 111In site per molecule, the quadrupole frequency increases by over 50% as the temperature is reduced below the freezing point of the solution. If two 111In sites are assumed there appears to be a change in the percentage occupancy of the two sites on either side of the transition.

Cycloheptanes↗