Biomedical subjects
Publications and source records attributed to K H Baker.
Helicobacter pylori was detected using molecular methods in untreated well water. The presence of H. pylori in the wells correlated with infection in consumers and with the presence of Escherichia coli, indicating fecal contamination. Consumption of untreated well water should be considered a risk factor for H. pylori infection.
The primary mode of transmission of the human pathogen Helicobacter pylori is unresolved. This study examined the possibility that H. pylori is water-borne. Because methods for the direct culture of H. pylori from water samples remain elusive, a microscopic technique was used for detection of this organism. Actively respiring micro-organisms binding monoclonal anti-H. pylori antibody were found in the majority of surface and shallow groundwater samples tested (n = 62), indicating that H. pylori may be present in aquatic environments in the US and supporting a water-borne route of transmission for this organism. There was no significant correlation between the occurrence of either total coliforms or Escherichia coli in the water and the presence of H. pylori. Our results indicate that routine screening of water supplies for the presence of traditional indicator organisms may fail to protect the consumer from exposure to H. pylori.
OBJECTIVES: Evaluate ENT endoscope sheaths as barriers to virus passage. STUDY DESIGN: "Defective" sheaths covering an endoscope were challenged with virus to determine how many virus particles could be recovered from the endoscope. METHODS: Sheaths with small laser-drilled holes (2 to 30 microm) were challenged with high-titer virus suspensions (10(8) viruses/mL). The inside of the sheath and the endoscope were separately rinsed to recover any virus that penetrated through the hole in the sheath. In an attempt to assess the possible importance of holes in the sheaths, a sequential test was conducted with an initial virus challenge outside a defective sheath (30-micron hole in the sheath), after which the possibly contaminated endoscope was removed and inserted into a second defective sheath (with a 20-micron hole at the same location) to determine whether the contaminating virus would pass outward through the second sheath. RESULTS: Small volumes of virus-containing fluid penetrated through the hole, e.g., 500 virus particles passed through one of three 30-microm holes. A significant fraction of those virus particles was occasionally found on the endoscope after removal from the sheath. Similar results were obtained with sheaths that had small tears (34-84 microm in length, from punctures with fine wires). Although some virus penetration could occur during the initial challenge contaminating the endoscope, no virus was detected passing outward through the second sheath. CONCLUSIONS: Use of a sheath combined with intermediate level disinfection should provide a safe instrument for ENT endoscopy.
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Enterobacter cloacae attached to drinking water distribution particles was subjected to chlorination. Attachment resulted in the protection of these organisms from disinfection. This effect was found to be dependent upon both the level of chlorine in the system and attachment time. The results obtained in this study indicate that attached organisms may play an important role in coliform outbreaks.
Varying the amount of labeled substrate or the amount of leaf material resulted in significant nonlinear changes in lignocellulose mineralization, as measured with natural [C]lignin-labeled lignocellulose. The use of periodic rather than continuous aeration was found not to have significant effects on measured mineralization.
Fluorescent antibody staining was combined with 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride reduction in a procedure termed FAINT to allow for the direct microscopic determination of specific actively respiring populations of bacteria in a variety of aquatic habitats. The FAINT procedure is simple, precise, and appropriate for use in a wide variety of autecological studies. The distribution of Thiobacillus ferrooxidans was examined by FAINT enumerations in both acidic and nonacidic sites. Comparisons among the FAINT technique and fluorescent antibody staining alone or most-probable-number determinations in 9K broth showed that the use of most-probable-number determinations resulted in an underestimation of the number of viable cells by one to three orders of magnitude, whereas fluorescent antibody counts resulted in an overestimation of the number of viable T. ferrooxidans. The amount of difference was not consistent but varied, depending on the sample site.
The marine diatom Thallasiosira pseudonanna (3H) and several bacteria associated with it were isolated from batch cultures at the University of Delaware mariculture facility. The interaction between the algae and each of the bacteria was investigated. One of the isolates, T827/2B (Pseudomonas sp.), was incapable of surviving in f/2 culture medium unless the algae were present. When the algae and T827/2B were grown together in the f/2 medium, the bacterial growth was stimulated and the algal growth was inhibited. Bacterial filtrate had a similar effect on the algae, indicating that the bacterial effect is an indirect one most likely resulting from the excretion of a harmful compound into the medium. Preliminary characterization of the material excreted by the bacteria indicates that it s proteinaceous in nature. The interactions observed does not fit into any single category of interactions but can be explained as a combination of competition and indirect parasitism.
Salivary immunoglobulin A (IgA) concentration increased significantly after subjects viewed a humorous videotape and did not change significantly after they viewed a didactic videotape. Scores on a questionnaire measuring the perceived use of humor as a coping skill were positively related to initial IgA concentration and inversely related to changes in IgA concentration after subjects' viewing of the humorous videotape, which implies a ceiling effect. Enhancement of the immune system may be one link between anecdotal claims of relationships between an individual's being in a positive emotional state and healing.
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Thyroid cancer is a rare and complex disease. The thyroid contains various cell types from which distinct diseases arise. These malignancies range from indolent to extremely aggressive. Diagnosis includes attention to risk factors, family history, and subjective reports. The most valuable tool for diagnosis is the fine-needle aspiration. Primary treatment is surgery with postoperative hormone therapy. Radiation and chemotherapy serve palliative and adjuvant roles in advanced, recurrent, or metastatic disease. Nurses make a significant contribution to patient understanding and successful treatment outcome.