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Biomedical subjects

F A Lewis

Publications and source records attributed to F A Lewis.

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

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.

Adolescent↗
PubMed1990

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.

DNA↗
PubMed1989

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.

Adult↗
PubMed1989

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.

Cell Line↗
PubMed1989

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.

Animals↗
PubMed1989

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.

Bicarbonates↗
PubMed1989

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.

Adolescent↗
PubMed1989

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.

Adolescent↗
PubMed1989

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.

Animals↗
PubMed1988

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.

Animals↗
PubMed1987

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.

DNA, Viral↗
PubMed1987

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.

Animals↗
PubMed1987

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.

Alkaline Phosphatase↗
PubMed1987

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.

Animals↗
PubMed1987

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.

Animals↗
PubMed1986

Immunocytochemical application of monoclonal antibodies to rat liver glucocorticoid receptor.

Seven per cent (10/145) of hybridomas raised against partially purified activated glucocorticoid receptor from rat liver produced monoclonal antibody to receptor. Six IgM secreting clones selected for further investigation bound equally well to activated and non-activated receptor from fresh rat liver, but significantly less well (11-25 per cent) to receptor from frozen rat liver. No interaction was found with oestrogen receptor from rat uterus but extensive cross reaction occurred with progesterone receptor. Although none of the antibodies bound to glucocorticoid receptor from human or porcine liver or lymphoid cells, several cross-reacted with mouse liver glucocorticoid receptor. Immunoelectroblotting of proteins from fresh and frozen rat liver cytosol showed the antibodies bound to 90,000 and 40,000 MW forms of receptor respectively. Immunostaining of both frozen and paraffin embedded sections of rat tissue showed that receptor is preserved during fixation and processing of tissues. Using both indirect immunoperoxidase and immunogold silver staining methods, the pattern of receptor staining observed correlates with the known glucocorticoid responsiveness of the tissues studied.

Animals↗
PubMed1986

Silicosis in a grey iron foundry. The persistence of an ancient disease.

An industrial hygiene and medical survey was conducted in an iron foundry to study the occurrence of silicosis. Breathing zone exposures to respirable crystalline silica had been very high in 1977 [1 045 micrograms/m3 (geometric mean) for coremakers and 198 micrograms/m3 for fettlers]; exposures in 1980 and 1982 were substantially lower. A radiographic evaluation of 188 workers revealed silicosis in 18 (9.6%). Eight had category 1 profusion of small rounded pulmonary lesions (by the 1980 classification of the International Labour Office); two had category 2; and eight had category 3. Two had progressive massive fibrosis. Four workers without silicosis in 1977 had developed lesions by 1980. The prevalence increased from 1.5% among workers employed less than 20 years to 53% among longer term workers. No association was found between the prevalence of silicosis and cigarette smoking. Chronic cough was more common in workers with heavy current dust exposure than in those with light exposure, more common in smokers than in nonsmokers, and more common in silicotics than in nonsilicotics. A multiplicative interaction existed between dust exposure and smoking in the etiology of cough. Silicosis continues to exist in American foundries. Cigarette smoking does not contribute to the causation of silicosis, but it aggravates the attendant respiratory symptoms.

Adult↗