MDCK cells (a line of stable canine kidney cells) infected with influenza A/NWS/33 virus (a neurotropic variant of the Wilson Smith strain) were tested with 18 selected bacterial species to determine whether mammalian cells become susceptible to bacterial adherence as a result of virus infection. Cell monolayers were washed and examined microscopically for adherence. Bacteria of only two of 18 species were seen to adhere to the infected cells: a group B Streptococcus and Streptococcus sanguis. Control monolayers were negative for adherence. Pretreatment of virus-infected cultures with mouse ascitic fluid containing antibody to influenza A virus completely blocked adherence of the bacteria. Further testing with the strains representative of the five serotypes of group B Streptococcus disclosed that adherence occurred with types Ia, Ic, and II, but not with types Ib and III.
Primary pancreatic carcinomas were studied histologically and histochemically, to assess the frequency of ductal hyperplasia in tissue adjacent to malignant neoplasms. Hyperplasia was divided into four types: simple, papillary, atypical and ductular, affecting large, medium and small ducts (ductules). All types of hyperplasia were frequently seen in areas adjacent to carcinomas, including ductal, pleomorphic, mucinous, adenosquamous, small and spindle cell and cystadenocarcinomas. In contrast, acinar cell carcinoma and microadenocarcinoma were less frequently associated with ductal hyperplasia. Mucin histochemistry revealed differences in types of mucin between the normal ducts and hyperplastic pancreatic ducts and carcinomas. The former group contained small amounts of sulphated mucin while the latter showed a marked increase in neutral and sialomucins. Our study also suggests that both papillary and atypical hyperplasia are precancerous lesions, supporting an hypothesis of ductal origin of pancreatic carcinomas.
A ferret model was used to study bacterial adherence in animals with influenza. Ferrets were inoculated intranasally with influenza A3/Hong Kong/ 1 /68 virus. Antiviral serum antibodies were apparent by Day 5. On Days 3, 5, 7, 9, and 1 I , three virus-inoculated and two uninoculated controls were anesthetized, exsanguinated, and decapitated, and the lower jaw was removed. Each animal was inoculated intranasally with a 1-ml suspension containing 20 mg (dry wt) of either 3H-labeled Staphylococcus aureus or 3H-labeled group B Streptococcus type Ia and incubated for 45 min at ambient temperature. In animals challenged with staphylococci, 80% of the original inoculum remained free in suspension; of the remaining 20%, the distribution in the upper respiratory tracts of virus-infected and control animals was significantly different. Of the staphylococci remaining in the nasopharynx of control animals, 74% was present in mucinous plugs, 1 1 % was bound to host cells present in washes of the nasal cavity, and 15% was released by protease treatment of the nasopharynx. Of the staphylococci remaining in the upper respiratory tract of virus-infected ferrets, 36% was recovered in plugs, 24% was bound to cells in nasal washes, and 40% was released by enzyme treatment. Overall, adherence-positive staphylococci represented 64% of recoverable bacteria in virus-infected ferrets versus 26% in controls. Adherence was increased twofold (Days 5 and 7) to threefold (Days 3, 9, and 11) in virus-infected ferrets compared to uninfected controls. In contrast, only 7% of the original streptococcal inoculum was recovered from virus-infected and uninfected control animals and virus infection did not enhance streptococcal adherence except for an approximately threefold increase that was seen on Day 11.
An enzyme-linked lectinsorbent assay (ELLA) was developed for quantification of in situ biofilm produced by Staphylococcus epidermidis in polystyrene 96-well tissue culture plates with phosphatase-labeled wheat germ agglutinin (WGA) as a specific probe for the GlcNAcbeta-1,4n component of exocellular matrix material (EMM) that is responsible for intercellular adhesion and accumulation. The ELLA and the modified Christensen dye assay were used to test 13 laboratory strains of coagulase-negative staphylococci and 10 clinical isolates of S. epidermidis. Four biofilm-positive laboratory strains of S. epidermidis were positive by both tests, and six biofilm-negative strains were negative by both. One strain of S. hemolyticus was positive by the ELLA only. Two of the 10 clinical isolates of S. epidermidis were positive by both assays, two were negative by both, and the remaining were positive by the ELLA only. The ELLA was objective, reproducible, specific, sensitive, and useful for screening strains for their capacity to adhere to plastic, produce EMM, and form biofilm.
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