Tracers for aerosol ventilation scintigraphy: Tc-99m versus In-113m

113mIn has been proposed as a suitable tracer for aerosol ventilation scintigraphy in combination with 99mTc pulmonary perfusion scintigraphy. The high energy (393 keV) of 113mIn allows it to be detected in the presence of 99mTc, but degrades the spatial resolution which can be achieved. We have compared the resolution obtained with 99mTc and 113mIn in phantom experiments and in aerosol ventilation scans in 14 patients with airways disease. The resolution at the distances from the collimator encountered in lung scintigraphy was 10-20 mm for 99mTc and 15-40 mm for 113mIn. Aerosol ventilation images were abnormal in all patients. The 99mTc images showed peripheral defects and frequently central hot spots reflecting increased local aerosol deposition. In the 113mIn images, the lower resolution had a smoothing effect, the central hot spots were less striking, and the distribution of activity appeared more uniform, some detail was lost in the periphery. It is suggested that 113mIn is useful for ventilation scintigraphy in the diagnosis of pulmonary embolism, but that 99mTc is the tracer of choice if aerosol ventilation scintigraphy is used to study airways disease.     

Determinants of survival in liver resection for colorectal secondaries

All 72 resections for colorectal liver secondaries during the period 1971-1984 were analysed retrospectively. Liver tumours were single in 35 (49 per cent), unilateral in 55 (76 per cent) and associated with extrahepatic disease in 12 (18 per cent) patients. Operative mortality was 5.6 per cent. With respect to the disease in the liver, the presence or absence of four or more metastases was the predominant prognostic determinant with a 5 year survival rate of 20 per cent in patients with less than four liver tumours, and no 3 year survivor among patients with four or more tumours. When the number of liver tumours was less than four, the prognosis in patients with unilateral disease was not significantly better than in patients with bilateral disease (P = 0.19). No other liver disease variable seemed to play any role in the prognosis. Extrahepatic disease was associated with a poor prognosis and no 5 year survivor. The length of the tumour-free resection margin was the only treatment variable that varied with the outcome: a resection margin of less than 10 mm was followed by a poor survival. Variables that did not influence survival included uni- or bilateral disease, liver tumour volume, tumour size, type of liver resection, Dukes' classification, differentiation of the primary tumour and synchronous or metachronous disease. It is concluded that resection for liver colorectal secondaries is indicated when there are less than four liver tumours, even if bilateral, no extrahepatic disease is present, and a resection margin of at least 10 mm can be obtained. It should not be performed unless all of these requirements are met.     

Current concepts in the treatment of disorders of micturition

Disorders of micturition may be divided into disturbances of the storage function of the bladder, and disturbances of the emptying function. The main symptoms of disturbances of storage function are frequency, urgency and incontinence. Hyperactivity of the bladder may lead to urge incontinence, and incompetence of the urethral closure mechanism to stress incontinence. There are many drugs available for treating bladder hyperactivity, but their efficacy as judged from controlled clinical trials (when available) is often limited. Bladder contraction in man is mediated by stimulation of muscarinic receptors, and when given parenterally anticholinergic drugs have been shown to depress bladder hyperactivity irrespective of the underlying cause. Clinically, however, treatment of urge incontinence with anticholinergic drugs is often unsatisfactory. Lack of effect of oral treatment and systemic side effects limit the use of available agents. Drugs with "mixed" actions (anticholinergic and 'direct' muscle effects), for example oxybutynin and terodiline, have well-documented efficacy in bladder hyperactivity. Side effects are common with oxybutynin; terodiline seems to be well tolerated. The aim of drug treatment of stress incontinence is to increase outflow resistance. Although there is only limited possibility of improving the condition with drugs, beneficial effects can be obtained in some patients by use of orally active alpha-adrenoceptor agonists (e.g. phenylpropanolamine) and/or oestrogens. The main symptom of disturbed bladder emptying is urinary retention. Drug therapy is aimed at improving the contractile activity of the detrusor or reducing urethral outflow resistance. Drugs used for improving bladder contractility include parasympathomimetic agents, e.g. bethanechol or carbachol, and intravesical instillation of prostaglandins. Although the efficacy of both types of treatment is open to question, bethanechol seems to be widely used. Increased outflow resistance may be seen in patients with parasympathetic decentralization of the lower urinary tract or in patients with benign prostatic hypertrophy. These patients may respond favourably to alpha-adrenoceptor blockers such as phenoxybenzamine or prazosin.     

Visual half-field tests of lateralized letter presentations: differences between preliterate and literate children

In the present study, hemispheric differences in global and analytic processing were investigated in preliterate and literate children, using the "dual-letter" matching task paradigm (Navon, 1977). The stimuli consisted of lateralized visual presentations of large uppercase letters made up of small uppercase letters. The task of the subject was to decide on each trial if the large or small letters were the same or not. Vocal reaction time (VRT) and error-frequency were used as dependent measures. In Experiment 1, 28 right-handed 8-years old children participated. The children were split into a preliterate and a literate group depending on teachers evaluations, and on scores on a reading test. The results showed longer VRTs for the preliterate children when the stimuli were initially presented to the right hemisphere and especially when the subjects were required to match the small letters. These results were followed up in Experiment 2, where the preliterate subjects were split into "fast" and "slow" readers. The results showed that the "slow" readers were more impaired in processing the letter stimuli when the stimuli were initially presented to the right hemisphere. It is concluded that hemispheric asymmetry for letter processing interacts with the development of normal reading ability in children.     

Follicular lymphoma cell lines,an in vitro model for antigenic selection and cytokine-mediated growth regulation of germinal centre B cells

In the periphery, B cells differentiate in germinal centres (GCs) of secondary lymphoid organs. Isolated GC cells die quickly in vitro by apoptosis. Therefore, cell lines originating from follicular lymphomas, which are the malignant counterparts of GC B cells, would provide a stable in vitro model to study the immunobiology of GC B cells. We have established three novel human follicular lymphoma cell lines that were characterized with special reference to immunophenotypic features, response to B-cell receptor (BCR) triggering, response to cytokines and cytokine mRNA expression. One of the cell lines, HF-1A3, has a phenotype of a centrocyte. It expresses surface immunoglobulin G (sIgG) and dies by apoptosis following BCR cross-linking. Co-stimulation with interleukin-6 (IL-6), IL-15 or interferon-gamma (IFN-gamma) rescues HF-1A3 cells from BCR-induced apoptosis. The second cell line, HF-28, also represents phenotypically an IgG+ centrocyte. Ligation of its BCR leads to the cell-cycle arrest at G1 instead of apoptosis. HF-28 cells express both CD45RA and RO isoforms, which is unusual in B lymphocytes apart from plasma cells, thus suggesting a transition to plasma cell phenotype. The third cell line, HF-4.9, which phenotypically represents an sIgM+ centroblast, responds by proliferation to BCR cross-linking. These cell lines offer a unique in vitro model to study antigenic selection and cytokine-mediated growth regulation of human GC B cells.     

Inclusion of a non-immunoglobulin binding protein in two-site ELISA for quantification of human serum proteins without interference by heterophilic serum antibodies

Measurement of human serum molecules with two-site ELISA can be biased by the presence of human heterophilic anti-animal immunoglobulin antibodies (HAIA) that cause false-positive signals by cross-linking the monoclonal (mAb) and/or polyclonal antibodies (pAb) used for the pre- (capture) and post-analyte steps (detection). To evaluate a novel ELISA format designed to avoid interference by HAIA, a target-specific non-immunoglobulin (Ig) affinity protein (affibody) was used to replace one of the antibodies. First, a human IgA-binding affibody (Z(IgA)) selected by phage display technology from a combinatorial library of a single Staphylococcus aureus protein A domain was used. The detection range of IgA standard using an ELISA based on Z(IgA) for capture and goat pAb against IgA (pAb(IgA)) for detection was comparable with that of using pAb(IgA) for both capture and detection. Secondly, another affibody (Z(Apo)) was combined with mAb and used to detect recombinant human apolipoprotein A-1. The affibody/antibody ELISAs were also used to quantify human serum levels of IgA and apolipoprotein A1. To verify that human serum did not cause false-positive signals in the affibody/antibody ELISA format, the ability of human serum to cross-link affibodies, mAb (mouse or rat) and/or pAb (goat) displaying non-matched specificities was assessed; affibodies and antibodies were not cross-linked whereas all combinations of mAb and/or pAb were cross-linked. The combination of affibodies and antibodies for analysis of human serum molecules represents a novel two-site ELISA format which precludes false-positive signals caused by HAIA.     

Interleukin 2 and gamma interferon production, interleukin 2 receptor expression, and DNA synthesis induced by tularemia antigen in vitro after natural infection or vaccination.

The T-cell response induced by Francisella tularensis antigen in sensitized subjects was characterized in vitro by measuring DNA synthesis in whole-blood and mononuclear cell cultures, interleukin 2 (IL-2) and gamma interferon (IFN-gamma) production, and IL-2 receptor expression. Correlations between these variables were estimated. The strengths of the responses were compared in 21 subjects naturally infected 2 years ago, 6 subjects vaccinated 5 to 6 years ago, and 13 control subjects with no history of infection or vaccination. Subjects with a history of natural infection synthesized more DNA in both whole-blood and mononuclear cell cultures, secreted more IL-2 and IFN-gamma, and expressed more IL-2 receptors than control subjects did. All these responses differed highly significantly (P less than 0.001) from those of the control subjects. The vaccinees exhibited somewhat lower responses than the naturally immunized subjects did, but the vaccinees could be distinguished from the control subjects by their DNA synthesis, receptor expression, and IFN-gamma production (P less than 0.01 to 0.001). The vaccinees showed a lower response, in terms of DNA synthesis and IL-2 secretion (P less than 0.05), than the infected group did but responded in a manner similar to that of this group, with respect to receptor positivity and IFN-gamma secretion (P greater than 0.10). The correlations between all the T-cell functions were good, with highly significant correlations (P less than 0.001) between whole-blood DNA synthesis and IL-2 and IFN-gamma secretion and between the two lymphokines (P less than 0.001). The results not only increase our knowledge of the T-cell response to tularemia antigen but also give an alternative approach to DNA synthesis measurement for the quantitation of T-cell responses. The results for the low-responding sensitized subjects seem to indicate that the parameters were comparable in sensitivity.     

Complete Sequence of a 93.4-kb Contig from Chromosome 3 of Trypanosoma cruzi Containing a Strand-Switch Region

We have initiated large-scale sequencing of the third smallest chromosome of the CL Brener strain of Trypanosoma cruzi and we report here the complete sequence of a contig consisting of three cosmids. This contig covers 93.4 kb and has been found to contain 20–30 novel genes and several repeat elements, including a novel chromosome 3-specific 400-bp repeat sequence. The intergenic sequences were found to be rich in di- and trinucleotide repeats of varying lengths and also contained several known T. cruzi repeat elements. The sequence contains 29 open reading frames (ORFs) longer than 700 bp, the longest being 5157 bp, and a large number of shorter ORFs. Of the long ORFs, seven show homology to known genes in parasites and other organisms, whereas four ORFs were confirmed by sequencing of cDNA clones. Two shorter ORFs were confirmed by a database homology and a cDNA clone, respectively, and one RNA gene was identified. The identified genes include two copies of the gene for alanine-aminotransferase as well as genes for glucose-6-phosphate isomerase, protein kinases and phosphatases, and an ATP synthase subunit. An interesting feature of the sequence was that the genes appear to be organized in two long clusters containing multiple genes on the same strand. The two clusters are transcribed in opposite directions and they are separated by an ~20-kb long, relatively GC-rich sequence, that contains two large repetitive elements as well as a pseudogene for cruzipain and a gene for U2snRNA. It is likely that this strand switch region contains one or more regulatory and promoter regions. The reported sequence provides the first insight into the genome organization of T. cruzi and shows the potential of this approach for rapid identification of novel genes.