An inexpensive, portable, battery-operated photometer for the reading of ELISA tests in microtitration plates.

We described an inexpensive, portable, battery-operated photometer which can read the enzyme-linked immunosorbent assay in 96-well microtitre trays. An example is given of its use to measure IgG antibody to human collagen type II in a serum sample from a rheumatoid arthritis patient known to have a high titre of antibody to cartilage by immunofluorescence. When the same samples were read first with the portable photometer and then in a spectrophotometer (Unicam SP 1800), the accuracy of the two devices was comparable, but the readings were obtained far more quickly in the photometer.

Mediastinal mixed dendritic cell sarcoma with hybrid features.

This report describes a recurrent sarcoma involving the soft tissues of the posterior mediastinum with features of both follicular dendritic and interdigitating dendritic cells. Histologically, the tumour, which was a recurrent neoplasm 19 years after the initial removal, was composed of bland spindle shaped cells with interspersed inflammatory cells, predominantly lymphocytes. Immunohistochemically, the spindle cells were positive for S100 protein, CD45, CD68, and vimentin, but negative for CD21 and CD35 (markers of follicular dendritic cells). The immunophenotype was in keeping with interdigitating dendritic cells. However, ultrastructural examination demonstrated elongated cell processes joined by desmosome-like junctions-features in keeping with follicular dendritic cells. Follicular dendritic cell sarcoma and interdigitating dendritic cell sarcoma are rare neoplasms and a high index of suspicion is required to make a correct diagnosis. Immunohistochemistry and/or electron microscopy are required for a definitive diagnosis. This case shows that hybrid neoplasms can occur, which have features of both follicular and interdigitating dendritic cells.

Jejunal crypt cell abnormalities associated with methotrexate treatment in children with acute lymphoblastic leukaemia.

Jejunal mucosal crypts were examined in jejunal biopsies from eight children with acute lymphoblastic leukaemia who had recently received methotrexate treatment. By comparison with biopsies from children under investigation for suspected malabsorption crypt mitosis was significantly reduced and showed a negative correlation with the dose of methotrexate given prior to biopsy. The three major cell types were studied under light and transmission electron microscopy. Gut endocrine cells were unaffected by therapy and immature crypt enterocytes showed only patchy degenerative abnormalities. By contrast a number of Paneth cells showed striking structural alterations with vacuolar dilatation of the cytoplasm. The extent of this correlated with the time since methotrexate treatment rather than its dose and may have been a functional response rather than of a toxic nature.

Tartrate resistant acid phosphatase positive splenic lymphoma: a relatively benign condition occurring in a time-space cluster?

Conventional light and electron microscopic studies, together with cytochemical and immunocytochemical staining procedures, were carried out to ascertain whether the lymphomata of four elderly female patients living within 10 kilometers of each other, who presented within a short space of time with massive splenomegaly and varying cytopenia, belonged to any particular subgroup of lymphoma. In each case the lymphoma had a diffuse pattern and mature B cell phenotype. The malignant cells were of uniform cell type, slightly larger than admixed polymorphonuclear leucocytes, and showed minimal nuclear irregularity and positivity for tartrate resistant acid phosphatase (TRAP) staining. Their clinical and morphological features were compared with those of other lymphoproliferative disorders, but while sharing some features in common with each condition, this small group of patients seemed to have a unique combination of findings. The cytopenias of all four responded well after removal of the spleen and their disease has not been aggressive. It is concluded that these patients have a distinct subgroup of lymphoma, which it is important to recognise so that inappropriate use of aggressive cytotoxic drugs can be avoided.

A sensitive single reverse passive haemagglutination test for detecting both HBsAg and anti-HBs.

A trial of a modified reverse passive haemagglutination test for HBsAg using a 0.1% cell suspension instead of the recommended 1% showed an approximately eight-fold increase in detection sensitivity. The test can be performed within 30 minutes and lends itself to mass screening techniques. Confirmation tests can be done using the 0.1% method. In addition, the same serological plates and cells used for HBsAg screening can then be used to screen for high-titre anti-HBs. This makes the overall screening for both HBsAg and high-titre anti-HBs donors cheap and convenient.

Confirmation of specificity by neutralisation in immunoradiometric assay for hepatitis B surface antigen.

Two types of neutralisation or blocking test using human anti-HBs are described for the confirmation of positive results obtained by immunoradiometric screening for HBsAg.

A sensitive immunoradiometric assay for the detection of hepatitis B surface antigen.

A solid-phase immunoradiometric assay for hepatitis B surface antigen is described which has been in use since 1971. Initially it was used for reference laboratory work, but from 1974 it has also been used for screening blood and blood products. Methods for the production of reagents and their use in blood transfusion and reference work are outlined.

Hepatitis B surface antigenaemia in Kenyans with chronic liver disease.

Fifty Kenyan patients with chronic liver disease or hepatocellular carcinoma were tested for hepatitis B surface antigenaemia by radioimmunoassay. The hepatitis B surface antigen was detected in 77% of the patients with chronic persistent or chronic aggressive hepatitis, or cirrhosis confirmed by liver biopsy, compared with 15% in a control group. All six patients with hepatocellular carcinoma had detectable hepatitis B surface antigen or antibody. 50% of the controls had hepatitis B surface antibody in their plasma detectable by haemagglutination. Auto-immune associated liver disease appeared infrequent. The possibility that the hepatitis B virus is an important cause of cirrhosis in Kenya is discussed.

Gastric paraganglioma: an immunohistological and ultrastructural case study.

This is a report of the immunohistochemical and ultrastructural features of a case of paraganglioma of the stomach in a 61-year-old woman who presented with melaena. The typical 'Zellballen' arrangement of epithelial cells with granular cytoplasm was present and the tumour was highly vascular. The polygonal epithelial cells stained strongly for neuron specific enolase and the intervening elongated sustentacular or support cells were positive for S100 protein and vimentin. Many dense core granules were present within the epithelial cells while the elongated support cells contained plentiful diffuse intermediate filaments. No hybrid cells or ganglion cells were present in the tumour. This is the sixth recorded case of gastric paraganglioma and the first to be studied in detail by immunostaining and electron microscopy.

Paraganglioma: an unusual tumour of the parathyroid gland.

A case of paraganglioma arising within a parathyroid gland is reported. The lesion was an incidental finding in a block dissection of neck performed for squamous carcinoma of the pharynx. A well-circumscribed lesion, exhibiting the characteristic pathological features of a paraganglioma, was embedded within the right inferior parathyroid gland. Due to its location, the chief histological differential diagnosis was an unusual variant of parathyroid adenoma. Immunohistochemistry and electron microscopy assisted in reaching a diagnosis. This, as far as we are aware, is the first reported case of a paraganglioma of the parathyroid gland.

Hepatitis C virus: evidence for sexual transmission.

OBJECTIVE: To determined the prevalence of hepatitis C virus infection and associated risk factors in patients attending a genitourinary medicine clinic, as evidence for sexual transmission. DESIGN: Seroprevalence estimated by reactivity in an enzyme immunoassay for antibodies to C100 protein with supplementary testing with a recombinant immunoblot assay and an assay for hepatitis C virus RNA. SETTING: Outpatient genitourinary medicine clinic in central London. PATIENTS: The panel of 1046 serum samples was from 1074 consecutive patients attending the clinic during November and December 1987 and having blood taken for routine testing for syphilis. Before samples were anonymised demographic and risk factor information was extracted from the clinic notes. Samples had already been tested for antibody to HIV-I and antibody to hepatitis B core antigen. MAIN RESULTS: Significantly more homosexual subjects than heterosexual subjects were positive for hepatitis C antibody determined by enzyme immunoassay alone (19/275 (6.9%) v 8/771 (1.0%), odds ratio 7.14, p less than 0.0001) and also when reactive serum samples were also tested by recombinant immunoblot assay (6/270) (2.2%) v 3/770 (0.4%), odds ratio 5.88, p less than 0.02). There were also significant associations in patients positive for hepatitis C antibody with positivity for antibodies to HIV and to hepatitis B core antigen, lifetime number of sexually transmitted diseases (homosexual men only), and age (all groups combined). Most patients whose serum samples contained specific antibodies to hepatitis C virus were viraemic. CONCLUSIONS: The study provides strong evidence for the sexual transmission of hepatitis C virus. Assays derived from other gene products are desirable to investigate the specificity and sensitivity of the enzyme immunoassay for C100 antibody as a marker of hepatitis C virus infection.

Barium granuloma of the transverse colon.

A case of barium sulphate granuloma of the transverse colon following gunshot wounds to the abdomen has been described. Scanning electron microscopy with electron probe microanalysis was used to confirm the presence of barium sulphate and the absence of lead or other elements related to the gunshot wounds.

Desmin myopathy with cardiomyopathy.

We report a case of abnormal desmin accumulation within the muscle of a 30-year-old female with a 2-year history of cardiomyopathy and axial muscle weakness. Serum creatine kinase was normal. A quadriceps muscle biopsy revealed pink hyaline inclusions, which stained for acid phosphatase and with PAS and were present in both fibre types. Electron microscopy showed these inclusions to consist of aggregates of irregularly arranged 6- to 15-nm-diameter filaments enmeshed within a central core of dense granulo-amorphous material. In other areas, the granulo-amorphous material lay as irregular patches within the sarcoplasm, mainly at the level of the "Z" band causing disruption of the sarcomere. Immunoelectron microscopy using colloidal gold showed that the dense amorphous material reacted strongly with desmin antisera and could, therefore, represent a defective or phosphorylated form of the protein.

The preparation of human articular cartilage for scanning electron microscopy.

This paper compares sixteen preparative techniques thought to be of advantage in the study by scanning electron microscopy (SEM) of human articular cartilage surfaces. The adequacy of surface preservation obtained with the techniques, was judged subjectively, first, by the reproducubility of secondary electron images of normal cartilage, and second, by comparing the results with those obtained by reflected light microscopy of the fresh unfixed cartilage surface over a magnification range of X20- X240. Adequate surface preservation was confirmed when cartilage surfaces had been dehydrated through ethanol to propylene oxide and vacuum dried; dehydrated through amyl acetate and quenched in Freon before freeze-drying; dehydrated and passed through amyl acetate at low temperature before freeze drying. Valuable information can be obtained from different specimens by varying the technique of preparation. At different ages, different surface features are best preserved. In a systematic study it has been found essential to adopt a uniform preparative method and to control the results by reflected light microscopy. Even with the most perfect preparation, the surface appearances cannot be identical with those that function under load in vivo.

The ultrastructural features of malakoplakia.

The ultrastructural features of a case of disseminated malakoplakia are described and compared with available published cases. Generally macrophages were involved (although characteristic inclusions were seen in association with some plasma cells) and contained three types of cellular inclusions. These were (1) the phagolysosomes (2) and intermediate structure sharing features of the phagolysosome and the Michaelis-Gutmann (MG) body and (3) the MG body. All inclusions were delineated by unit membranes and their matrices (except those of large MG bodies) composed of membranous whorls and loops. It is suggested that these inclusions represent stages in the development of the MG body. Septate junctional complexes were observed between phagolysosomes and small MG bodies. These complexes may represent either a mechanism of organelle fusion or an abnormality of molecular organisation of the limiting unit membrane.