Schistosoma mansoni larvicidal activity of murine bronchoalveolar lavage cells

We have investigated the ability of cells obtained from both normal and immune mice by bronchoalveolar lavage (BACs) to kill Schistosoma mansoni larvae in vitro. In cultures with mechanically derived schistosomules, high levels of larvicidal activity were displayed by BACs from both normal and irradiated cercaria-immunized C57BL/6 mice. Based on effector-to-target-cell ratios, BAC-mediated killing was two- to threefold more efficient than killing mediated by macrophage-rich cell populations obtained from the peritoneal cavity. BACs from normal A/J mice were essentially as larvicidal as normal C57BL/6 cells. However, BACs from a strain of mouse (P/J) with a known macrophage defect possessed negligible larvicidal activity. Macrophages made up 85 to 95% of BACs from all three strains tested. In contrast to cells of the IC-21 macrophage cell line, B6 BACs did not show enhanced killing activity when preincubated with lymphokine-containing supernatants. Lung schistosomules harvested 10 days after cercarial penetration were refractory to BAC-mediated killing.

Epstein-Barr virus associated oesophageal ulcers in AIDS

Epstein-Barr virus (EBV) associated ulceration has not previously been included in the differential diagnosis of oesophageal ulcers in AIDS. We report five cases of oesophageal ulceration in homosexual men with advanced human immunodeficiency virus infection in whom this was considered to be the most likely cause. DNA in situ hybridisation studies showed EBV in biopsy material from three of four patients with oesophageal ulcers and in none of three controls. Of other viruses studied, only human papillomavirus was present, and this was found in both patients and control subjects. These findings support the hypothesis that EBV is an aetiological factor in some cases of AIDS-associated oesophageal ulceration.

Application of 1 nm gold probes on paraffin wax sections for in situ hybridisation histochemistry

An in situ hybridisation technique that uses 1 nm immunogold reagents and silver enhancement was devised to detect biotinylated DNA viral probes in formalin fixed, paraffin wax sections of human cervix. DNA probes labelled with biotin-11-deoxyuridine triphosphate were detected after hybridisation to nucleic acid sequences by an antibiotin antibody, followed by a gold labelled secondary antibody. Silver enhancement then permitted visualisation of the signal at the light microscopic level. The method was reliable and produced less background staining than previously described methods. The signal could be enhanced by epi polarisation microscopy. Furthermore, biotinylated DNA probes may be detected directly by a 1 nm gold labelled goat antibiotin antibody without loss of labelling intensity, and this may be preferable to the longer two layer technique, previously described.

Tissue extraction of DNA and RNA and analysis by the polymerase chain reaction

Several DNA extraction techniques were quantitatively and qualitatively compared using both fresh and paraffin wax embedded tissue and their suitability investigated for providing DNA and RNA for the polymerase chain reaction (PCR). A one hour incubation with proteinase K was the most efficient DNA extraction procedure for fresh tissue. For paraffin wax embedded tissue a five day incubation with proteinase K was required to produce good yields of DNA. Incubation with sodium dodecyl sulphate produced very poor yields, while boiling produced 20% as much DNA as long enzyme digestion. DNA extracted by these methods was suitable for the PCR amplification of a single copy gene. Proteinase K digestion also produced considerable amounts of RNA which has previously been shown to be suitable for PCR analysis. A delay before fixation had no effect on the amount of DNA obtained while fixation in Carnoy's reagent results in a much better preservation of DNA than formalin fixation, allowing greater yields to be extracted.

Schistosoma mansoni: influence of Biomphalaria glabrata size on susceptibility to infection and resultant cercarial production

Biomphalaria glabrata snails of the same age, but different sizes, were used to determine size-related susceptibility to Schistosoma mansoni miracidial infection and the influence of snail size on total cercarial production. Snails with shell diameters from less than 5 to greater than 17 mm were individually exposed to one or several miracidia, depending on the experiment. In snails exposed to multiple numbers of miracidia, the percentage of snails which developed patent infections was lower in snails with larger shell sizes. This was also reflected by fewer primary sporocysts per infected snail found in tissues of the larger snails. Upon determining cercarial production in these groups over a 1-month period there were no statistical differences between any groups in the numbers of cercariae produced per snail. However, upon determining the number of successful primary sporocysts found in cohort snails of each size group, cercarial production increased as a function of the number of successful primary sporocysts. This was verified by examining cercarial production in various size snails with known monomiracidial infections. Our data therefore confirm and extend earlier work using snails infected with unknown numbers of miracidia and clearly show that total S. mansoni cercarial development and decreased susceptibility of snails is a direct reflection of snail size and not necessarily age of the snail.

Extraction of DNA from exfoliative cytology specimens and its suitability for analysis by the polymerase chain reaction

The extraction of DNA from archival exfoliative cytology samples would allow the molecular biological analysis of this readily available material using the polymerase chain reaction (PCR). We have quantitatively and qualitatively studied the extraction of DNA from a variety of cytological preparations. For both fresh and archival cervical smears, overnight incubation with proteinase K produces high yields of high molecular weight DNA, but simply boiling the samples produces DNA suitable for PCR amplification of a single copy gene. Increasing the proteinase K incubation to several days allows the extraction of DNA from fixed and stained archival cytology slides from a variety of sites. The extracted DNA was again suitable for PCR analysis. Fresh and archival cytological material can be utilized for molecular biological study of disease processes using PCR. Archival cytological material is probably the best source of DNA and RNA after stored frozen tissue.

Demonstration of Epstein-Barr virus in primary brain lymphoma by in situ DNA hybridisation in paraffin wax embedded tissue

Tumour tissue from 29 patients with primary brain lymphoma was reviewed to determine if there was an aetiological association between Epstein-Barr virus and polyclonal and monoclonal lymphoproliferations. The morphology and immunophenotype in 24 patients for whom paraffin wax embedded tissue was available were studied. A high grade pleomorphic tumour morphology with plasmacytoid features was seen in 13 tumours. Because of the large number of pleomorphic lymphomas, all tumours were examined for the presence of the Epstein-Barr virus genome using in situ DNA hybridisation. A panel of three biotinylated probes to different sequences in the Epstein-Barr virus genome was used. Positive hybridisation with one or more probes was shown in tumours from 11 patients. The remaining tumours gave no hybridisation signal. There was no correlation between positive hybridisation and morphological subtype or clinical outcome.

Demonstration of multiple HPV types in normal cervix and in cervical squamous cell carcinoma using the polymerase chain reaction on paraffin wax embedded material

The prevalence of human papilloma virus (HPV) types 6, 11, 16 and 18 was investigated using the polymerase chain reaction on formalin fixed, paraffin wax embedded material in 19 cases of cervical squamous cell carcinoma and in 10 normal cervices. HPV DNA was detected in 16 of 19 carcinomas, with multiple types present in 11 of these. HPV 16 or 18, or both, were present in all cases in which HPV was shown. Six of 10 cases of normal cervix contained HPV; five of these contained two or more HPV types, including HPV 16 or 18, or both. This study shows the feasibility of using the PCR on paraffin wax embedded material and indicates a high rate of carriage of multiple HPV types in both normal and neoplastic cervix.

Extraction and amplification of DNA from archival haematoxylin and eosin sections and cervical cytology Papanicolaou smears

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A genomic change associated with the development of resistance to hycanthone in Schistosoma mansoni

Ribosomal gene probes were used to investigate the genetic basis of drug resistance in schistosomes in a model where resistance to the anthelmintic hycanthone (HC) is generated by exposing immature worms to the drug. Two strains of Schistosoma mansoni, JHU and NMRI, were used. Drug resistance could be produced in the JHU strain by treatment with HC, but was also found to occur spontaneously. In contrast, it was not possible to detect or produce resistance to HC in the NMRI strain. A genomic alteration accompanied the development of resistance. The change was evidence by the occurrence of restriction fragment length polymorphisms (RFLPs) when Southern blots of genomic DNA from HC-resistant worms were hybridized with the ribosomal probe pSM389, which contains part of the small rRNA gene plus non-transcribed spacer (NTS) sequence. The most reliable marker of HC-resistance was a 3.6-kb BamHI fragment which was present and heritable in 7 drug-resistant lines derived from the JHU strain but absent from the parent JHU population and from NMRI parasites. The universal absence of the 3.6-kb RFLP in HC-sensitive individuals and its presence in the drug-resistant progeny suggest that resistance results from an induced change in the population rather than from selection of HC-resistant parasites. The rRNA gene sequence responsible for detecting the 3.6-kb RFLP appears to be localized either to the NTS or to the 5' end of the small rRNA gene, since hybridization to a probe containing sequence from the rRNA gene contiguous and downstream from the insert of pSM389 failed to reveal the RFLP. These results show that the development of resistance to HC is accompanied by a genomic rearrangement.

In situ hybridization technique using an immunogold silver staining system

An in situ hybridization technique using an immunogold silver staining detection system was used to detect biotinylated DNA probes in cultured cells and in formalin-fixed paraffin-embedded tissue. The detection method is rapid, reliable and economical, producing an insoluble signal at the site of hybridization which is visible at low-power light microscopy and which can be enhanced by epipolarization microscopy.

Laryngeal papillomatosis: correlation between severity of disease and presence of HPV 6 and 11 detected by in situ DNA hybridisation

A technique using a biotin-streptavidin polyalkaline phosphatase complex was applied to routinely fixed and processed biopsy specimens of laryngeal papillomata from 45 patients taken over the past 20 years to detect human papilloma virus (HPV) types 6 and 11. Two thirds of both adult and juvenile onset cases were positive for HPV 6 or HPV 11 or both. Five specimens of normal vocal cord epithelium were negative for HPV 6 and 11. The detailed clinical history, endoscopic findings, success of treatment and eventual prognosis were compared with the HPV state of biopsy material for each patient. Patients with multiple confluent lesions when first seen, whose histology showed florid koilocytosis and who had strongly positive reactivity for HPV 6 or 11 present in the surface epithelial cell nuclei, had a poor prognosis requiring multiple endoscopies to control their disease.

Re-establishing a life cycle of Schistosoma mansoni from cryopreserved larvae

To study the feasibility of re-establishing a life cycle of Schistosoma mansoni (NMRI strain) from cryopreserved larvae, schistosomules were suspended in the cryoprotectant 1,2-ethanediol and cryopreserved in liquid nitrogen. Mice were injected intramuscularly with samples thawed after 3 days, 3 wk, or 6 mo in liquid nitrogen storage. Two to 5% of the cryopreserved larvae and approximately 18% of corresponding unfrozen control larvae developed into adult worms. Infectivity did not decrease as a function of storage time. The adult worms showed no structural damage or changes in overall size and morphology when examined by light and transmission electron microscopy. Female worms derived from cryopreserved larvae had the same or slightly elevated egg production as controls, but tissue egg distributions were comparable. Subsequent passages through Biomphalaria glabrata snails and mice revealed no difference in snail prepatent death rate, percentage of snails infected, cercarial production per snail, or cercarial infectivity.

The identification of cells containing JC papovavirus DNA in progressive multifocal leukoencephalopathy by combined in situ hybridization and immunocytochemistry

A double-labelling technique combining in situ hybridization and immunocytochemistry is described which was used to characterize cells in the central nervous system containing JC virus DNA in formalin-fixed, paraffin-embedded tissues from four cases of progressive multifocal leukoencephalopathy. All four cases showed positive nuclear labelling for JC virus in both oligodendrocytes and astrocytes. The latter gave a strongly positive cytoplasmic staining reaction using antibodies to glial fibrillary acidic protein and vimentin. No nuclear labelling of neurones or endothelial cells was noted. The results confirm previous suggestions that glia are the main cells infected by JC virus in this disorder and show that the distribution of viral DNA in the brain is more extensive than suggested by routine microscopy alone. In situ hybridization for JC virus may be useful in confirming the diagnosis of progressive multifocal leukoencephalopathy in both surgical biopsies and post-mortem brain tissue.

Juvenile and adult laryngeal papillomata: classification by in-situ hybridization for human papillomavirus

We report the application of an in-situ hybridization technique for the demonstration of human papillomavirus (HPV) employing a biotin-streptavidin-polyalkaline phosphatase complex to paraffin processed tissue from a series of patients with laryngeal papillomata. All cases of juvenile papillomata, whether solitary or multiple, proved positive for HPV types 6 and/or type 11. However, only two cases of adult solitary papillomata and five cases of adult multiple papillomata were positive for HPV type 6 and/or type 11. All papillomata were negative for HPV types 16 and 18. Five specimens of normal vocal cord epithelium were uniformly negative for all four HPV types.

An evaluation of common cerumenolytic agents: an in-vitro study

Four non-prescription cerumenolytic agents were acquired over the counter of a high-street chemist and evaluated along with Sodium Bicarbonate ear drops BP, olive oil, distilled water, and acetone in an in-vitro study. Sodium Bicarbonate ear-drops BP are used by the nurses in the department and are recommended in the British National Formulary as the most effective solution to soften cerumen prior to syringing. Acetone was included as an effective organic solvent. The test was performed in a water bath, controlled to match the temperature of the external auditory meatus. Disintegration of the cerumen was noted over a two-hour period. Substantial disintegration occurred with three products: Waxsol, Stores Own Brand, and distilled water.

Schistosoma mansoni: relationship between cercarial production levels and snail host susceptibility

Two populations of Biomphalaria glabrata snails differing slightly in their susceptibility to Schistosoma mansoni infection showed dramatic differences in cercarial output per snail. Exposed to five or more miracidia, snails from a group with a 90-100% susceptibility rate (Group A) produced nearly twice the number of cercariae as those from a group with a 70-80% susceptibility rate (Group B). Exposure of individual snails to known numbers of miracidia resulted in higher numbers of primary (mother) sporocysts in Group A snails than in Group B snails. However, monomiracidial exposure of snails from both groups resulted in equivalent numbers of cercariae produced per positive snail, indicating that, once established, all primary sporocysts possess a similar reproductive potential. Morphometric analysis of serially sectioned 9-day-old primary sporocysts supported this conclusion; the size of the primary sporocysts and the size and numbers of secondary (daughter) sporocysts within each primary sporocyst were comparable in snails from both groups. The data indicate cercarial production in this system is regulated prior to, and/or during, early development of the primary sporocyst.

Demonstration of human papillomavirus types 6 and 11 in juvenile laryngeal papillomatosis by in-situ DNA hybridization

A study is reported in which an in situ hybridization technique for the demonstration of human papillomavirus (HPV) employing a biotin--streptavidin polyalkaline phosphatase complex has been successfully applied to formalin-fixed paraffin-processed tissue obtained from ten patients with juvenile laryngeal papillomatosis. In all cases, positive results were obtained for either HPV type 6 or 11. Normal vocal cord epithelium was negative.

Intraspecific cross-protection in mice immunized with irradiated Schistosoma mansoni cercariae

Several laboratory-maintained strains of Schistosoma mansoni were tested for their relative immunogenicity or susceptibility to anti-schistosome immunity in irradiated cercaria-immunized mice. A total of 11 strains and substrains were used; 7 were of Puerto Rican origin, 3 from Brazil, and 1 from Egypt. Mice were immunized by percutaneous exposure to 50-krad-irradiated cercariae. Immunity was assessed following challenge with cercariae of the homologous or a heterologous strain. The results showed that the choice of either the challenge or immunizing strains was not critical in the development of significant levels of protection. Extensive degrees of cross-protection developed in all intrastrain combinations tested.

Vaccine-induced immunity in mice against Schistosoma mansoni trickle cercarial infections

Experiments were performed to determine the level of protection in immunized mice to multiple small (trickle) Schistosoma mansoni cercarial challenges. C57BL/6 mice were immunized with either 50 Krad-irradiated cercariae or a soluble worm antigenic extract injected intradermally in conjunction with the adjuvant BCG. A series of cercarial challenges (40 cercariae per exposure), beginning approximately one month after immunization, was given at 4-week intervals. To prevent any contribution of egg-related pathology, the mice were exposed to male cercariae only. The results showed that highly significant levels of protection developed at all times after cercarial challenge. Regardless of the type of immunization or the number of cercarial challenges, the levels of protection which appeared after one, two, three, or four challenge exposures were nearly identical, and equalled those in mice exposed at a single time to a cumulative total of the several exposures. As expected, titers of anti-schistosome antibodies were higher in the immunized and challenged groups than in those challenged alone, and titers increased anamnestically after challenge infection. However, increased antibody titers were not associated with increased resistance in trickle challenged mice. Overall, we showed that the level of vaccine-induced immunity does not change, under these conditions, in the face of repeated cercarial challenges. Also, these results show that single mass cercarial challenges may legitimately be used in experimental situations to assess the effectiveness of vaccines which might be used in subjects repeatedly exposed to cercariae in field situations.

Macrophage activation as an immune correlate to protective immunity against schistosomiasis in mice immunized with an irradiated, cryopreserved live vaccine

Immune responses against Schistosoma mansoni were evaluated in C57BL/6 mice injected with one of two populations of irradiated schistosomules, the larval preparations differing only in the degree of freezing-induced damage sustained upon cryopreservation. Mice injected with larvae which successfully withstood cryopreservation showed a significant reduction in worm burden following cercarial challenge. No protection was achieved in mice which received larvae damaged by a suboptimal thawing rate. Parallel comparison of several humoral and cellular responses in mice which received either inoculum revealed that induction of activated macrophages and production of macrophage-activating lymphokine activity were the strongest correlates to development of protective immunity. Protected mice also showed marginal 30-min skin test reactivity and weak but transient 24-h delayed-type hypersensitivity to a soluble adult worm preparation. In contrast, indistinguishable levels of circulating antibodies to soluble and tegumental antigens developed in the two immunization groups, and antigen-stimulated lymphocyte blastogenic responses were strong and essentially equivalent in magnitude. These studies strongly suggested that in this new model for investigating anti-schistosome effector mechanisms, responses contributing to the development of activated macrophages may be essential for induction of protective immunity.

Sensitive in situ hybridisation technique using biotin-streptavidin-polyalkaline phosphatase complex

A sensitive in situ hybridisation technique, using a biotin-streptavidin-polyalkaline phosphatase complex detection system, was successfully applied to smears of fresh cultured cells, frozen sections, and formalin fixed paraffin processed tissue: the procedure was successful for DNA-DNA hybridizations using a variety of DNA probes. The detection method is rapid, reliable, and economical producing a purplish-blue precipitate at the site of hybridisation and clearly visible by low power light microscopy.