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Biomedical subjects

L K Harding

Publications and source records attributed to L K Harding.

At least 37 records · Page 2Linked to original sources
PubMed1994

Effect of agitation on the quality of platelet concentrates.

Platelet concentrates (PCs) were stored for 4 days at 22 degrees C in 400 ml second-generation (PL1240) platelet packs with either constant agitation, manual mixing once every 24 h or without agitation at any time. After 4 days storage, in vivo recovery, survival and biodistribution were determined following indium-111 labelling of platelets and infusion into autologous volunteers. In vitro assays of platelet function and biochemistry were likewise carried out after 4 days storage. The PCs stored without agitation had significantly lower in vivo recoveries, pH and aggregation responses to ionophore A23187 and a combination of collagen and epinephrine and significantly higher beta-thromboglobulin and indium-111 release than the agitated PCs. The manually mixed PCs were not significantly different from the constantly agitated PCs. PCs mixed simply once every 24 h remained viable with active oxidative phosphorylation and a pH above 6.74 in all but 1 case indicating that PCs stored at 22 degrees C for up to 4 days with only intermittent mixing are satisfactory for transfusion. A change from constant agitation would reduce capital costs in mixing equipment and simplify the transport of PCs from the transfusion centre to small hospital blood banks.

Blood Banks↗
PubMed1994

Simplified method for the measurement of segmental colonic transit time.

Segmental colonic transit has been measured in 101 patients. Two MBq of 111Indium absorbed on resin pellets and encapsulated in an enteric coated capsule was given at 7 00 am. Hourly images during the first day, and three images during each subsequent day were acquired for up to three days. Using all scan and patient data the scans were categorised in one of the five patterns of colonic transit: normal, rapid, right delay, left delay, or generalised delay. The geometric centres and per cent activity at each time point was compared between the five groups of colonic transit patients to find the best time for imaging and so to distinguish the five groups. During the first day, early images did not help in diagnosis of patterns of transit, however, in the later images (six hours onwards after the ingestion of the activity) the rapid transit groups could be identified. Images at 27 and 51 hours were both required to distinguish all five groups of patients from each other. Only in the 'normal' transit patients was there some excretion of the activity during the course of the second day, otherwise there was no difference in the images taken in the course of a day (second or third day). A simplified protocol requires a minimum of three images to distinguish all five patterns of colonic transit. The activity should be ingested in the morning (7 00 am) and the first image taken at the end of the working day (8-10 hours after ingestion), the second image on the morning of the second day, and the third image during the course of the third day. This simple protocol would provide all the clinically relevant information necessary for correct classification of the colonic transit.

Adolescent↗
PubMed1993

Where do we stand with the International Commission on Radiological Protection Report 60?

We have examined the implications of ICRP60 for nuclear medicine. Radiation doses to staff are currently low and reduction of the dose limits will have little impact. However, the proposed figures for the fetus may have implications for pregnant women where the workloads are high. With nursing staff on the ward, laboratory staff or indeed departmental porters there seems little problem. Radiation dose to the fingers is, however, a key factor, and ensuring that no further restrictions are placed on the proposed dose limits is important. The concept of constraints is becoming clearer but will need further thought, particularly with regard to exposure of the general public. The previous basis for declaring controlled and supervised areas has been abandoned, and the situation is now less clear. A most important area of debate will be the patient who is a controlled area, and great care will have to be taken to ensure that the number of patients in this category is not increased so that many more patients need to be kept in hospital. Exposure of the general public is also an issue and expanding the concept of medical exposure to include carers is an important development. This should prevent a number of unnecessary restrictions and adds weight to the point that two waiting rooms are not justified in nuclear medicine departments. ICRP recommendations will soon be incorporated into the legislation of member states and it is import for everyone to ensure that drafts are read carefully and that national proposals are not too restrictive.

Europe↗
PubMed1993

Scintigraphic defecography: quantitative and dynamic assessment of anorectal function.

PURPOSE: Conventional assessment of anorectal function with defecating videoproctography is semiquantitative and the high radiation exposure precludes prolonged or repeated testing. The aim of this study was to develop a dynamic scintigraphic method of assessing anorectal function. METHODS: Fourteen patients with fecal incontinence, 18 patients with chronic constipation, and 8 control subjects were assessed by scintigraphic defecography. This involves introduction of a technetium-99m-radiolabeled artificial stool into the rectum of the subject and acquisition of gamma camera images during evacuation. RESULTS: Mean evacuation rate was 2.8 percent/second in incontinent patients and 0.9 percent/second in constipated patients (P < 0.001). The mean anorectal angles were 136 degrees and 133 degrees, respectively. There were 18 cases of pelvic floor descent and 6 rectoceles. Scintigraphic defecography provides quantitative information on rectal evacuation. Anorectal angle and pelvic floor movement can be examined. The radiation dose to pelvic organs is significantly less than with videoproctography. CONCLUSION: We believe that scintigraphic defecography is the investigation of choice for objective and dynamic assessment of anorectal function.

Adult↗
PubMed1993

Evaluation of the inflammatory infiltrate in pouchitis with 111In-labeled granulocytes.

BACKGROUND: The aim of this study was to elucidate the inflammatory infiltrate in pouchitis and define the changes following metronidazole therapy. METHODS: Twenty-seven patients underwent functional grading, sigmoidoscopic and histological scoring, 111In-labeled granulocyte scanning, and 4-day fecal collections for 111In-labeled granulocyte excretion. Six of the patients with pouchitis underwent repeat studies after 1-month treatment with metronidazole, 400 mg three times daily. RESULTS: The grade of macroscopic inflammation in the pouch mucosa (sigmoidoscopic score) correlated well with the acute histological score (P < 0.0001), chronic histological score (P < 0.001), 4-hour 111In scan (P < 0.001), 24-hour 111In scan (P < 0.001), and with 4-day fecal 111In excretion (P < 0.001). After metronidazole therapy there was decreased inflammatory grade sigmoidoscopically and histologically on the 4- and 24-hour scans and decreased 4-day fecal 111In granulocyte excretion. CONCLUSIONS: This study confirms that the inflammatory infiltrate in pouchitis is acute or chronic, is characterized by neutrophils, is usually localized to pouch mucosa, and is always decreased after metronidazole therapy.

Acute Disease↗
PubMed1993

Measurement of colonic transit time using radionuclide imaging: analysis by condensed images.

A polymer-coated capsule has been used in eight volunteer subjects to deliver 111In-resin into the ileocaecal region. The images were acquired for up to 3 days to follow transit through the colon. Expressing the results of individual studies is difficult and time-activity curves for each region are confusing. Calculation of the geometric centre indicates only where the middle of the activity has reached. We describe a new method of presenting colonic transit data as parametric images. The parametric images show the amount of activity in each area of interest as the study progresses. This is readily understood and allows segmental movement of the isotope, either forward or retrograde, to be examined. The geometric mean of activity in four areas of the colon were also calculated. Four hours after reaching the ileocaecal region, 65% (S.D. 24%) of the activity was in the caecum and 26% (S.D. 20%) in the transverse colon. By 24 h three controls had excreted most of the activity, in two the activity was mainly in the rectum and in two there was still some activity in the transverse colon. A protocol for colonic transit studies, problems with analysis and a new method of presentation of data are discussed.

Acrylic Resins↗
PubMed1993

Radioimmunoscintigraphy of recurrent colorectal carcinoma using 111In-labelled murine monoclonal antibody B72.3: a comparison with contrast-enhanced computed tomography.

Ten patients underwent contrast-enhanced abdominal computed tomographic (CT) carcinoembryonic antigen (CEA) measurement and murine 111In-B72.3 monoclonal antibody radioimmunoscintigraphy for recurrent or residual colorectal carcinoma. All patients had undergone primary colorectal tumour resection at a median of 3 (range 1-18) months previously. Histological analysis of pelvic tissue biopsies confirmed that six patients had recurrent or residual colorectal cancer and that four were tumour free. Whilst scintigraphy correctly showed all six patients with recurrent or residual disease, both CT and CEA measurement were correct in only four patients. In the four patients without recurrent cancer, CT was correct in two patients whilst scintigraphy and CEA measurement were accurate in three patients. Six out of the 10 patients showed marked nonspecific colonic excretion of radiolabelled antibody which was correctly interpreted in five patients. Future prospective studies comparing CT scans, CEA estimation and B72.3 radioimmunoscintigraphy in a larger group of patients with suspected residual or recurrent colorectal adenocarcinoma may help to define the respective sensitivity and specificity of these techniques.

Aged↗
PubMed1993

White cell scans and infected joint replacements. Failure to detect chronic infection.

We report the results of imaging with labelled white cells in 52 patients before the revision of 54 cemented joint prostheses at which the diagnosis of infection was made from biopsies. Twenty-five hips were imaged with 111In-oxine-labelled cells; 20 hips and 11 knees were imaged with 99mTc-hexamethylpropylene-amineoxime-labelled cells. Of these, 13 hips and five knees proved to be infected. The scans taken together had an accuracy of 82%, a sensitivity of 44% and a specificity of 100%. Indium scans gave 37% sensitivity, 99mTc labelling 50% sensitivity. Infected arthroplasties with positive scans had presented significantly earlier than those with negative scans, the time after the original insertion being 1.1 years for the true-positive scans and 6.1 years for the false-negative scans. The value of labelled white-cell scans in the detection of infection in failed joint replacements is dependent on the activity of the infection. There is reduced sensitivity to the more insidious infections which affect arthroplasties and aspiration under controlled conditions remains an important investigation.

Biopsy, Needle↗