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F A Lewis

Publications and source records attributed to F A Lewis.

At least 37 records · Page 2Linked to original sources
PubMed1995

Suppressive effect of interleukin-4 neutralization differs for granulomas around Schistosoma mansoni eggs injected into mice compared with those around eggs laid in infected mice.

The principal pathological manifestation of murine Schistosoma mansoni infection is the egg-induced granuloma. Synchronous pulmonary granulomas forming around intravenously injected schistosome eggs are widely used to study the immunopathology of schistosomiasis. A number of anticytokine antibody treatments have a remarkable effect in modulating granulomas in this model but little effect on the size of hepatic granulomas around laid eggs during experimental infection. To examine this discrepancy, we examined the effects of anticytokine antibodies on liver and lung granulomas around injected eggs and around eggs laid during infection in both locations. Anti-interleukin-4 (IL-4) treatment greatly reduced the volume of granulomas around eggs injected into the liver via the portal vein and around eggs injected into the lung via the tail vein. On the contrary, granulomas around eggs laid by worms in either the liver or the lung during the course of infection were not significantly decreased in size by anti-IL-4 treatment. Thus, site is not important for the disparate effects of anti-IL-4 in granuloma formation around injected versus laid eggs. This effect is seen in naive and sensitized animals and is most probably due to differences in the quality of injected eggs versus those laid in situ by the worms.

Animals↗
PubMed1995

Comparison of two strains of Schistosoma mansoni with respect to the sites and kinetics of immune elimination in irradiated cercaria-immunized mice.

A comparison was made of the sites of elimination of NMRI and Mill Hill strains of Schistosoma mansoni in C57BL/6J mice previously immunized with 50 krad gamma-irradiated cercariae of the homologous strain. In the first experiment, the fate of percutaneous challenge infections with 75Se-labeled cercariae was evaluated by autoradiography of tissue squashes and hepatic portal perfusion. For both strains of parasite, migration from skin to lungs was delayed but not reduced in immunized mice relative to controls, with immune elimination taking place at some point after migration to the lungs. In a second experiment, resistance to the Mill Hill strain of S. mansoni was compared in mice challenged by percutaneous infection with cercariae and by intravenous injection with lung schistosomula. Both types of challenge were shown to be vulnerable to immune elimination. We conclude that under the conditions employed in this study, there is no significant difference between the NMRI and Mill Hill strains of S. mansoni in the patterns of migration and elimination, with most or all elimination in both control and immunized mice taking place after migration from the skin.

Animals↗
PubMed1994

Elevated expression of Th1 cytokines and nitric oxide synthase in the lungs of vaccinated mice after challenge infection with Schistosoma mansoni.

C57BL/6 mice were vaccinated with irradiated cercariae of Schistosoma mansoni, and, at various times after challenge infection, total lung mRNA was isolated to assess the induction of several cytokines that previously had been shown in in vitro studies to be involved in the activation of macrophages and/or endothelial cells for nitric oxide (NO) production and killing of schistosomula. Vaccinated mice demonstrated a highly significant increase in IFN-gamma mRNA upon subsequent infection when compared with infected nonvaccinated controls. A similar, although less dramatic, increase in two other macrophage-activating cytokines, TNF-alpha and IL-2, also was observed. In contrast, although the Th2 cytokines IL-4, IL-5, IL-10, and IL-13 were elevated in challenged vaccinated animals, only IL-10 and IL-13 showed increases that were significant with respect to the mRNA levels observed in challenged controls. Neutralization of IFN-gamma reduced immunity in vaccinated animals and resulted in decreased IFN-gamma, IL-2, IL-10, TNF-alpha, and IL-12 p40 but markedly increased IL-4, IL-5, and IL-13 mRNA expression and serum IgE levels. Pulmonary NO synthase expression was elevated in immunized mice at a time at which immune elimination of schistosomula is believed to occur. Moreover, suppression of NO synthase activity with the inhibitor aminoguanidine reduced immunity, as measured by a 32 to 33% increase in worm burden. Together, these data support previous in vitro studies that suggest a role for NO in schistosomulum killing. Furthermore, the observation that the down-regulatory cytokines IL-4, IL-10, and IL-13 are induced together with IFN-gamma may provide an explanation for the failure of this vaccine to provide complete protection.

Amino Acid Oxidoreductases↗
PubMed1994

Schistosoma mansoni: relationship between low fecundity and reduced susceptibility to parasite infection in the snail Biomphalaria glabrata.

Biomphalaria glabrata snails which were not susceptible as juveniles to infection by Schistosoma mansoni were selectively bred (by self-fertilization) from the highly susceptible NMRI laboratory snail stock. The susceptibility rate among juvenile snails derived from interbreeding NMRI parents was initially 85-95%, but after several generations of selection, less than 5% of exposed snails became infected by the parasite. Selection for low susceptibility also resulted in a large proportion of snails that displayed low fecundity and produced abnormal egg masses. Individual adult snails which were isolated from an interbreeding population of nonselected NMRI snails usually produced well-developed egg masses each containing 15-30 embryos. However, when juvenile snails from this same population were reared in isolation and not allowed to cross-fertilize, many displayed a pattern of low fecundity and abnormal egg production similar to that observed in the selected low susceptible line. Furthermore, it was found that many of the isolated snails which exhibited low egg production were also not susceptible to parasitic infection.

Animals↗
PubMed1994

The importance of fixation procedures on DNA template and its suitability for solution-phase polymerase chain reaction and PCR in situ hybridization.

Conventional solution-phase polymerase chain reaction (PCR) and in situ PCR/PCR in situ hybridization are powerful tools for retrospective analysis of fixed paraffin wax-embedded material. Amplification failure using these techniques is now encountered in some centres using archival fixed tissues. Such 'failures' may not only be due to absent target DNA sequences in the tissues, but may be a direct effect of the type of fixative, fixation time and/or fixation temperature used. The type of nucleic acid extraction procedure applied will also influence amplification results. This is particularly true with in situ PCR/PCR in situ hybridization. To examine these effects in solution-phase PCR, beta-globin gene was amplified in 100 mg pieces of tonsillar tissue fixed in Formal saline, 10% formalin, neutral buffered formaldehyde, Carnoy's Bouin's, buffered formaldehyde sublimate, Zenker's, Helly's and glutaraldehyde at 0 to 4 degrees C, room temperature and 37 degrees C fixation temperatures and for fixation periods of 6, 24, 48 and 72 hours and 1 week. DNA extraction procedures used were simple boiling and 5 days' proteinase K digestion at 37 degrees C. Amplified product was visible primarily yet variably from tissue fixed in neutral buffered formaldehyde and Carnoy's, whereas fixation in mercuric chloride-based fixatives produced consistently negative results. Room temperature and 37 degrees C fixation temperature appeared most conducive to yielding amplifiable DNA template. Fixation times of 24 and 48 hours in neutral buffered formaldehyde and Carnoy's again favoured amplification.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1994

Genetic diversity of Schistosoma mansoni: quantifying strain heterogeneity using a polymorphic DNA element.

Intraspecific genetic variation among 14 geographic isolates of Schistosoma mansoni was quantified using a molecular marker to examine individual genotypes. Genetic crosses demonstrated maternal inheritance of S. mansoni DNA element pSM750. This element revealed diagnostic banding profiles, which allowed accurate strain identification. Most strains had similarity indices greater than 0.75 indicating that within-strain variation in these laboratory parasite populations was low. However, individual parasites from the NMRI strain were quite diverse (S = 0.40). Genetic heterogeneity among strains was quantified using a phenogram of mean genetic distance. Strain diversity between two geographic regions was quantified using a similarity index and was estimated to be substantial among isolates collected from a single local site.

Animals↗
PubMed1994

Human papilloma viruses: a study of their prevalence in the normal larynx.

The association of human papilloma viruses (HPV) with laryngopharyngeal squamous cell carcinoma is under investigation. The suitability of control tissue in the reported series, invariably obtained from histologically normal tissue adjacent to a squamous cell carcinoma or from patients with benign laryngopharyngeal disease, is questionable. The present study determined the prevalence of HPV in a series of normal larynges. Twelve autopsy larynges were collected. DNA was obtained by SDS proteinase K digestion. Evidence of HPV infection was documented by the polymerase chain reaction using oligonucleotide primers complementary to sequences in the E6 region of HPV types 11, 16 and 18. Four female and eight male larynges, mean age 65 years (SD = 16 years) were collected 72 hours postmortem (median value). HPV type 11 was isolated from three specimens. A 25 per cent prevalence rate for HPV 11 was found. No other HPV types were isolated.

Adult↗
PubMed1994

Frequency of allele loss of DCC, p53, RBI, WT1, NF1, NM23 and APC/MCC in colorectal cancer assayed by fluorescent multiplex polymerase chain reaction.

We report here the use of multiplex fluorescent polymerase chain reaction (PCR) for quantitative allele loss detection using microsatellites with 2-5 base pair repeat motifs. Allele loss of APC, DCC, p53 and RB1 in colorectal tumours has been reported previously using a variety of methods. However, not all workers used intragenic markers. We have used microsatellite polymorphisms which map within, or are closely linked to, these tumour-suppressor gene loci in order to determine whether these loci are indeed the targets for alteration in colorectal cancer. In addition, we have assayed two other tumour-suppressor genes, WT1 and NF1, to see whether they play a role in colorectal carcinogenesis. The putative metastasis-suppressor gene, NM23, was also investigated since there have been conflicting reports about its involvement in colorectal carcinogenesis. Allele loss was detected at the DCC (29%), p53 (66%), RB1 (50%) and NF1 (14%) loci and in the APC/MCC region (50%), but not at the WT1 or NM23 loci. These rapid, and mostly gene-specific, fluorescent multiplex PCR assays for allele loss detection could be modified to devise a single molecular diagnostic test for the important lesions in colorectal cancer.

Adenocarcinoma↗
PubMed1994

A search for candidate viruses in type 1 diabetic pancreas using the polymerase chain reaction.

In order to investigate a possible viral aetiology for Type 1 diabetes the polymerase chain reaction (PCR) technique was used. Pancreatic tissue from Type 1 diabetic subjects was examined for the presence of a panel of common viruses. Primers specific for mumps, measles, cytomegalovirus, and Epstein Barr virus, as well as primers located in a highly conserved region of the enterovirus genome which are capable of detecting all of the following family members: Coxsackie B, echovirus, polio, mengovirus, and encephalomyocarditis virus were used to screen 18 Type 1 diabetic subjects of whom 3 had proven insulitis, 12 Type 2 diabetic subjects and 18 non-diabetic controls. Epstein Barr virus was detected in two Type 1 (13%), two Type 2 (22%), and three of the normal nondiabetic pancreases (20%), and the DNA sequences confirmed by direct sequencing. Cytomegalovirus was detected in one of the normal pancreases only and no evidence of any of the other viruses was found. It is concluded that the Type 1 diabetic pancreatic samples studied did not show persistence of infection with any of the above viruses. Non-persistent acute infection of the pancreas by the above viruses cannot be excluded in the aetiology of Type 1 diabetes from this study.

Accidents↗
PubMed1994

PCR in situ hybridisation detection of HPV 16 in fixed CaSki and fixed SiHa cell lines.

AIMS: To investigate the feasibility of using fixed cells with the polymerase chain reaction (PCR) in situ hybridisation and to investigate possible reasons for reaction failure. METHODS: Fixed SiHa and CaSki cells were used in an experimental model of PCR in situ hybridisation for the detection of low and intermediate copy number viral infection in fixed cells. RESULTS: PCR in situ hybridisation was able to detect one to two copies of human papillomavirus (HPV) 16 in SiHa cells, using small fragment amplicons (120 base pairs), confirming the high detection sensitivity and flexibility of the technique. Problems were encountered with localisation of PCR amplified product in CaSki cells (200-300 copies of HPV 16 per cell) owing to diffusion of product post amplification. Overall, 40% of reactions were successful, which confirms the current unreliability of the technique. Within cell preparations, about 50% of cells contained amplified product. CONCLUSION: PCR in situ hybridisation represents the marriage of two revolutionary molecular pathological techniques. However, it is currently unreliable, with reaction failure common. Standardised, dedicated equipment is urgently required if the technique is to achieve universal acceptance. In the future, the technique may be used to detect chromosomal translocations in human tumours and to study cellular gene expression.

Base Sequence↗
PubMed1994

In situ hybridisation for the identification of Helicobacter pylori in paraffin wax embedded tissue.

A method for identifying Helicobacter pylori using a non-isotopic in situ hybridisation technique is described. A probe generated by polymerase chain reaction (PCR) with primers directed against parts of the Helicobacter pylori 16SrRNA sequence was used. Paraffin wax embedded gastric biopsy specimens from patients with and without gastritis were hybridised with the probe, and the method was shown to be sensitive and specific for H pylori.

Base Sequence↗
PubMed1993

Analysis of cytokine mRNA expression during primary granuloma formation induced by eggs of Schistosoma mansoni.

Granulomas induced by parasite eggs are the primary lesions in mice infected with Schistosoma mansoni. Temporal analysis of cytokine mRNA expression in lung tissue containing synchronized granulomas demonstrated a Th0-like pattern of lymphokine expression. IFN-gamma, IL-1 beta, and IL-6 were the primary cytokines induced by day 1 in developing lung granulomas initiated by i.v. egg injection. These changes were followed by increases in expression of IL-2, IL-4, and IL-10 mRNA on day 3 and TNF-alpha and IL-5 mRNA on day 6. Nearly all cytokine mRNA reached maximal levels by day 6, which preceded the peak in granuloma size seen on day 14. In vivo treatment of egg-injected mice with either anti-IL-2 or anti-IL-4 antibodies significantly diminished the size of circumoval granulomas in the lungs. Both groups of antibody-treated animals displayed a marked reduction in IL-4 as well as IL-5 mRNA expression, although IFN-gamma and IL-2 mRNA levels were unchanged or slightly increased. These findings confirm previous observations suggesting a role for IL-2 in egg-induced pathology via the generation of Th2-associated responses, and also indicate a primary function for IL-4 in granuloma formation. Analysis of responses after injection of eggs into nude mice demonstrated that only the Th2 cytokines IL-4 and IL-5 are exclusively dependent on T cells for their induction. Taken together, these data suggest that Th2 cells producing IL-4 play a major role in egg granuloma formation, and that the induction and ultimate down-modulation of Th2-like responses may be influenced by non-T-cell-derived cytokines.

Animals↗
PubMed1993

Schistosoma mansoni: analysis of an unusual infection phenotype in the intermediate host snail Biomphalaria glabrata.

Snails from a B. glabrata stock, selected for nonsusceptibility to the NMRI strain of S. mansoni, exhibited unusual schistosome infections, with multiple sporocysts prominent in the head-foot (foot-sporocysts). When F1 progeny from numerous crosses between well-defined susceptible (S) and resistant (R) parental snails were exposed, 60% of the infected snails also exhibited this unusual phenotype. F1 progeny from S x S snail crosses developed normal infections. Foot-sporocysts usually developed much later than secondary sporocysts of normal infections and before 12 weeks postexposure the tissue reaction surrounding foot-sporocysts was less intense than reactions to sporocysts in other tissues of the body. Cercariae were seen emerging directly from foot-sporocysts. Infection of S x R hybrid progeny by three other strains of S. mansoni also resulted in the production of foot-sporocysts. Development of the foot-sporocyst infection phenotype in progeny from many snail crosses suggests that this phenotype is more common than previously recognized. Over 50% of the F1 progeny from S x R parental crosses developed patent infections, a fact relevant to the possible biological control of schistosomiasis by the introduction of refractory snails into endemic areas.

Animals↗
PubMed1993

Prognostic value of p53 overexpression and c-Ki-ras gene mutations in colorectal cancer.

BACKGROUND: Mutations in Ki-ras codon 12 and the p53 gene are common abnormalities in colorectal cancer. The occurrence of p53 overexpression and/or Ki-ras codon 12 mutations were analyzed in 100 colorectal adenomas to determine if they were related to patient survival. METHODS: p53 overexpression was identified by immunohistochemistry, and Ki-ras codon 12 mutations were detected using the polymerase chain reaction and a restriction enzyme digestion method. RESULTS: p53 overexpression was identified in 45% of tumors, with a higher frequency identified in DNA aneuploid and left-sided tumors than in DNA diploid and right-sided tumors. Mutations in Ki-ras codon 12 were identified in 24% of carcinomas. Individually, mutations in Ki-ras codon 12 or p53 overexpression were not prognostic indicators of survival. However, a statistically significant difference in survival was identified when these two oncogenic abnormalities were analyzed together. The median survival of patients whose tumors contained both oncogenic abnormalities was less than half of that of patients with either alteration alone or without either abnormality. CONCLUSIONS: Screening for multiple genetic abnormalities in colorectal cancers excised at surgery may prove to be a useful tool in determining prognosis.

Adenocarcinoma↗
PubMed1993

Morphine physical dependence in the hibernator: central nervous system mechanisms underlying the development of dependence remain functional during depression induced by pentobarbital anesthesia.

Earlier work suggested that adaptive mechanisms of the hibernating brain may also block the development of morphine physical dependence. To test an alternate view that CNS depression itself might be the major factor in the failure of dependence to develop, we compared the strength of dependence produced by morphine (two 75-mg pellets, s.c.) given for 12 hr in the presence, versus in the absence, of continuous pentobarbital anesthesia in nonhibernating ground squirrels (Citellus lateralis) and, in addition, in rats. Dependence was measured by the naloxone (5 mg/kg, s.c.) evoked abstinence syndrome in the awake state. The results demonstrated that pentobarbital-induced general anesthesia does not significantly reduce the development of morphine dependence in either species. We conclude that CNS depression alone does not account for the hibernation-related reduction in morphine physical dependence.

Anesthesia↗