Application of reflectance spectroscopy to the estimation of uric acid, urea and glucose: an evaluation of the Ames Seralyzer

An original approach to the measurement of analytes in clinical chemistry has now become available, in which dry reagent strip technology is linked to measurement by reflectance spectroscopy. The present studies have evaluated the performance of the first of these test systems—for uric acid, urea and glucose, in serum—by comparison with conventional liquid chemistry methods. Satisfactory performance in terms of both precision and accuracy was obtained for all three test systems, the current “state-of-the-art” performance criteria being met; the Seralyzer system proved reliable and easy to use in the hands of trained operators. It should find a place as a “Stat” analyser in the laboratory, in specified wards and in Health Centres.     

Bacterial persistence and immunity in goats vaccinated with a purE deletion mutant or the parental 16M strain of Brucella melitensis.

To evaluate host responses, young goats were inoculated subcutaneously with a genetic deletion mutant (deltapurE201) of Brucella melitensis (n = 6), its virulent parental strain 16M (n = 6), or saline (n = 6). No clinical evidence of brucellosis was seen in any goat. Serum antibody titers peaked at postinoculation day (PID) 14. Bacteria in lymph nodes that drained sites of vaccination reached peak numbers of >10(6) CFU/g in both infected groups at PID 7 and progressively declined to PID 84. At necropsy, bacteria were present in mammary lymph nodes or spleen of 33% of goats given virulent 16M but in none of goats given the purE mutant. Lymphadenitis, most severe in goats given 16M, involved depletion of lymphocytes and germinal centers, proliferation of lymphoblasts, and vasculitis. By PID 28, lymph node architecture was restored; there was marked germinal center formation and medullary plasmacytosis. Brucellar antigens, detected with immunoperoxidase techniques, were prominent in capsular granulomas but not in lymph node cortices. Ultrastructurally, bacteria were found in macrophages (>97%) and small lymphocytes (<3%) but not in large lymphocytes. Bacteria were intact in small lymphocytes but in macrophages were in various stages of degradation. The deltapurE phenotype of deltapurE201 was preserved during infection of goat lymph nodes. Unlike Salmonella spp. purE mutants, strain deltapurE201 may be a candidate for efficacy testing; it produced immune responses, was cleared from visceral tissues, and produced less severe pathologic changes than its wild-type parent.     

The neuroendocrine stress hormone norepinephrine augments Escherichia coli O157:H7-induced enteritis and adherence in a bovine ligated ileal loop model of infection

The role of the neuroendocrine environment in the pathogenesis of enteric bacterial infections is increasingly being recognized. Here we report that norepinephrine augments Escherichia coli O157:H7-induced intestinal inflammatory and secretory responses as well as bacterial adherence to intestinal mucosa in a bovine ligated ileal loop model of infection. Norepinephrine modulation of enteritis and adherence was dependent on the ability of E. coli O157:H7 to form attaching and effacing lesions.     

Effects of Lymphocyte Isolation and Timing of Processing on Detection of CD127 Expression on T Cells in Human Immunodeficiency Virus-Infected Patients

Decreases in the detection of CD127 expression on T cells of human immunodeficiency virus-infected patients by flow cytometry can occur by delayed processing or by peripheral blood mononuclear cell isolation and cryopreservation. These observations should be considered in the interpretation of functional studies and the planning of multicenter clinical trials.     

Childhood B cell lymphomas arising in the mediastinum.

AIMS--To report the clinical features and pathology of four childhood cases of primary mediastinal non-Hodgkin's lymphoma of non-lymphoblastic pathology. METHODS--Biopsy material was fixed in formol-saline and routinely processed and stained. Immunohistochemical staining was performed on paraffin wax embedded sections using the alkaline phosphatase anti-alkaline phosphatase method. RESULTS--The four patients presented with a large mediastinal mass and symptoms consistent with superior vena cava syndrome secondary to lymphoma. None of the patients had any clinically important disease outside the mediastinum. The four tumours had a histological appearance similar to diffuse large cell non-Hodgkin's lymphoma with sclerosis. Immunohistochemical staining showed that these tumours were of B cell origin. One patient died from infection during treatment and two patients died with progressive disease. The remaining patient remained well 43 months off all treatment. CONCLUSIONS--These four cases further illustrate the heterogeneity of paediatric large cell lymphomas. Clinically, they seem to be equivalent to the B cell lymphoma of the mediastinum, sclerosing type, that is seen in young (predominantly female) adults. The clinical and biological features of this type of tumour in childhood are largely unknown. Using standard treatment protocols, this tumour seems to have a poor prognosis and its optimal treatment therefore requires further clarification.     

Salmonella enterica serovar Typhi possesses a unique repertoire of fimbrial gene sequences

Salmonella enterica serotype Typhi differs from nontyphoidal Salmonella serotypes by its strict host adaptation to humans and higher primates. Since fimbriae have been implicated in host adaptation, we investigated whether the serotype Typhi genome contains fimbrial operons which are unique to this pathogen or restricted to typhoidal Salmonella serotypes. This study established for the first time the total number of fimbrial operons present in an individual Salmonella serotype. The serotype Typhi CT18 genome, which has been sequenced by the Typhi Sequencing Group at the Sanger Centre, contained a type IV fimbrial operon, an orthologue of the agf operon, and 12 putative fimbrial operons of the chaperone-usher assembly class. In addition to sef, fim, saf, and tcf, which had been described previously in serotype Typhi, we identified eight new putative chaperone-usher-dependent fimbrial operons, which were termed bcf, sta, stb, ste, std, stc, stg, and sth. Hybridization analysis performed with 16 strains of Salmonella reference collection C and 22 strains of Salmonella reference collection B showed that all eight putative fimbrial operons of serotype Typhi were also present in a number of nontyphoidal Salmonella serotypes. Thus, a simple correlation between host range and the presence of a single fimbrial operon seems at present unlikely. However, the serotype Typhi genome differed from that of all other Salmonella serotypes investigated in that it contained a unique combination of putative fimbrial operons.     

Use of trehalose-mannitol-phosphatase agar to differentiate Staphylococcus epidermidis and Staphylococcus saprophyticus from other coagulase-negative staphylococci.

Using a plate medium containing trehalose, mannitol, and phenolphthalein diphosphate (TMPA), we differentiated significant clinical isolates of Staphylococcus epidermidis by their lack of acid production in 18 h from other coagulase-negative staphylococci, with our results having a sensitivity (R. S. Galen and S. R. Gambino, Beyond Normality: The Predictive Value and Efficiency of Medical Diagnoses) of 100%, a specificity of 89.9%, and a positive predictive value of 94.8%. With a Taxo A bacitracin disk, which differentiates Staphylococcus species from Micrococcus species, no zone of inhibition was seen for 96% of all staphylococcal strains, with 5 of 26 strains of Staphylococcus saprophyticus exhibiting zone diameters up to 10 mm. By using resistance to a 5-microgram novobiocin disk, we differentiated S. saprophyticus, with our results having a sensitivity of 100%, a specificity of 97.1%, and a positive predictive value of 83.9% on TMPA. These two species represented 77.8% of coagulase-negative staphylococci isolated. Reference strains fo Staphylococcus and Micrococcus species were differentiated by TMPA. The cost of TMPA was compared with that of another method. TMPA was found to offer an inexpensive, sensitive method for rapidly differentiating coagulase-negative Staphylococcus isolates.     

Comparison of various techniques for determining viability of Paracoccidioides brasiliensis yeast-form cells.

The viability of Paracoccidioides brasiliensis yeast-form cells was determined by colony-forming units, direct fluorescent staining, and production of germ tubes in slide culture. The first procedure was unreliable and time consuming; the latter two showed better correlation with hemacytometer total cell counts and required significantly less time.     

Cellular immune response during uncomplicated genital infection with Chlamydia trachomatis in humans.

Extraction of staphylococcal abscesses by the Folch procedure revealed that all of the staphylocidal activity was present in the lipid fraction. Further separation of the lipids indicated that the bactericidal activity resided in the free fatty acid pool. Lipids similarly extracted from mesenteric or epididymal fat tissue, either before of after activation, did not possess comparable activity. Myristic, palmitic, palmitoleic, linoleic, and oleic acids, as well as lysolecithin, also failed to exhibit the properties of the fatty acid fraction obtained from abscess homogenates. These findings suggest the staphylocidal fatty acid is not a common host lipid.     

“Smart” Materials for Biosensing Devices: Cell-Mimicking Supramolecular Assemblies and Colorimetric Detection of Pathogenic Agents

Mimicking cell membrane and the biomolecular recognition associated with membranes represents a great technical challenge, yet it has opened doors to innovative diagnostic and therapeutic methods. Our work has focused on design and synthesis of a class of smart materials exploiting biological principals for use in biosensors: these materials are functional polymeric assemblies that mimic the cell membrane and conveniently report the presence of pathogens with a color change. Biologically active cell membrane components are incorporated into conjugated polymers with desirable optical properties and the binding of the target molecules onto the material triggers conformational and electronic shifts that are reflected in a chromatic change (a so-called biochromic shift) that is conveniently observed and recorded. Langmuir–Blodgett thin films and vesicle bilayers provide ideal configurations for precise delivery of the biological binding entity to the sensing interface, and for control of molecular orientation for effective biomolecular interaction. Polydiacetylenic membrane-mimicking materials containing cell surface receptor gangliosides and sialic acid residues, respectively were formulated into these architectures and used for colorimetric detection of bacterial toxins and influenza virus. One advantage of these biochromic conjugated polymer (BCP) sensors is that their molecular recognition and signal transduction functionalities are resident in a single functional unit, making them amenable to convenient microfabrication and use.