Preparation and characterization of monoclonal antibodies against aflatoxin B1

Five hybridoma cell lines producing monoclonal antibodies (MAb) against Aflatoxin B1 (AFB1) were established after fusion of mouse myeloma cells (SP-2/O-Ag-14) with spleen cells isolated from male BALB/c mice immunized with AFB1-BSA conjugate. Among these, one MAb, designated AFB1-2H8, was of the subtype IgG3 and the acidic fluid of which gave high dilution titers (1:5 x 10(5). The sensitivity of a competitive inhibition enzyme immunoassay (CIEIA) using AFB1-2H8 for AFB1 demonstrated that the linear range was 0.5-50 ng/ml and the minimum detectable concentration of AFB1 was 0.01 ng/ml. The specificity of the MAb was determined and showed no significant crossreaction with any of the metabolites tested. So th-- MAb and the CIEIA described may be useful in the detection of AFB1 in food and feed.

Free-space regular optical interconnections: a mathematical analysis

The matrix descriptions for three types of free-space regular optical interconnection networks, the perfect shuffle, the banyan, and the crossover, are given. Some new properties of the perfect shuffle are presented in matrix equations, and the equivalence of the three types of interconnection networks is simply shown.

Cloning, expression, and characterization of Cryptococcus neoformans dihydrofolate reductase

The Cryptococcus neoformans dihydrofolate reductase (DHFR) gene has been isolated from cDNA and genomic DNA libraries. The 690-base pair coding sequence codes for a 25,152-Da protein, which is the largest monofunctional DHFR yet reported. The gene contains two introns, and several putative regulatory sequences have been identified. The coding sequence was placed in a pUC-based expression vector, which expresses C. neoformans DHFR in Escherichia coli at a level of about 5% of the total soluble extract. The expressed DHFR was purified to homogeneity by methotrexate-Sepharose affinity chromatography, followed by anion exchange chromatography on Q-Sepharose. On SDS-polyacrylamide gel electrophoresis, the purified enzyme migrates as a single protein with apparent mass of 28 kDa. The molecular weight, as determined by electrospray mass spectral analysis, and the amino-terminal sequence are in accord with what was predicted from the DNA sequence. Steady state kinetic parameters, effects of pH, salts, and inhibition constants of several anti-folates have been determined.

Optical perfect-shuffle-exchange interconnection network using a liquid-crystal spatial light switch

The perfect-shuffle-exchange interconnection network (e.g., the omega network) is a type of free-space regular multistage interconnection network. An equivalent omega network that consists of left- and right-perfect-shuffle interconnects as well as spatial light switch devices is described. An optical omega network that uses two special polarization prisms and a liquid-crystal spatial light switch is presented. The experimental results of a 8 x 8 omega network are reported. The optical omega network has the features of simple architecture and ease of integration.

Enhancement of the protective effect of inactivated influenza virus vaccine by cytokines

The authors examined whether or not cytokines in conjunction with inactivated influenza virus vaccine enhance protection from influenza virus infection in mice. Mice were infected with influenza virus A/PR/8/34 (PR/8) at 10 LD50 by nebulizer after intranasal administration of the cytokine and the vaccine. The survival rate of the group which received both the vaccine and mouse recombinant interferon-beta (MuIFN-beta; 1 x 10(4) IU/mouse) or mouse recombinant interferon-gamma (MuIFN-gamma; 1 x 10(4) IU/mouse) was significantly higher than that of the control group given the vaccine alone. These results show that MuIFN-beta and MuIFN-gamma have an adjuvant effect on this vaccination. In contrast, human recombinant interleukin-2 (HuIL-2) and human recombinant tumour necrosis factor (HuTNF) did not have an adjuvant effect. In order to examine the mechanism of the enhancing effect of MuIFN-gamma on this vaccination, we determined the specific IgA and IgG antibodies present in bronchoalveolar lavage fluid (BALF) and serum, and haemagglutination inhibition (HI) antibody in serum. In the early stage of infection, the titres of IgA and IgG antibodies in the combined group receiving the vaccine with MuIFN-gamma showed a tendency to be higher than those in the group given the vaccine alone. In the late stage of infection, the titre of HI antibody in the group given the vaccine with MuIFN-gamma was significantly lower than that in the group given vaccine alone. It can be concluded from these results that a part of the adjuvant effect of MuIFN-gamma on this vaccination was due to an increase in production of antibodies which neutralized the virus in the lesion.

Treatment of Staphylococcus aureus nasal carriers in CAPD with mupirocin

We have studied the efficacy of topical Mupirocin for elimination of Staphylococcus aureus (Staph. aureus) nasal carriage in CAPD patients. Staph. aureus nasal carriers in our CAPD program were randomized to one of two groups: Group 1, treated with Mupirocin, and Group 2, treated with neomycin sulphate nasal ointment. The prevalence of Staph. aureus nasal colonization was 44% for patients (24/54) and 17% for dialysis partners (5/29). Group 1 included 11 patients and 1 partner, and Group 2, 8 patients and 2 partners. In Group 1, the eradication rate was 100%, and the recolonization rate was 0, 8, 41, 55 and 66% at 1, 2, 3, 6 and 10 months. In Group 2, the eradication rate was 40%, with a recolonization rate of 0.25 and 75% at 1, 2 and 3 months. Re-treatment with mupirocin was successful in 66% of the cases, compared to 20% for neomycin. The MIC90 of mupirocin for Staph. aureus was 0.5 mcg/mL, with an increase to 4 mcg/mL towards the end of the study. During the study period, there was a very low incidence of Staph. aureus peritonitis or catheter-related infections in patients treated with mupirocin. Secondary effects of mupirocin were negligible. Mupirocin is more effective than neomycin sulphate for the elimination of Staph. aureus nasal colonization in patients undergoing CAPD. Periodic re-treatment is frequently necessary, given the significant recolonization rate.

[A comparison between antigliadin antibodies and blood xylose in celiac disease]

We have compared serum antigliadin antibodies (AGA) with xylose absorption test in diagnosis and follow-up of pediatric celiac disease. Three groups of children were investigated: celiacs, affected by other gastrointestinal disease, healthy controls. On gluten diet AGA IgA, IgG and xylose test were abnormal in all celiac children. After only three months of gluten-free diet, abnormal AGA IgA values were found in 3%, AGA IgG in 63%, xylose test in 28% of children. Normal values for AGA IgA and IgG and for xylose test were found between 7 and 20 months. On challenge, after 1-4 months of gluten diet, abnormal AGA IgA and IgG values were found in 90% of cases, xylose test only in 27%. As far as the children with other gastrointestinal disease are concerned, 2% had abnormal values for AGA IgA, 22% for AGA IgG and 42% for xylose test. All healthy children had normal AGA IgA, IgG values and xylose test. Our date show AGA IgA the most specific laboratory test, among these investigated, for diagnosis and follow-up of celiac disease.

Low frequency hearing threshold determination in newborns, infants and mentally retarded children by middle latency responses

Middle latency (10-50 ms) responses (MLR) evoked by tone-pips (1,000 Hz 500 Hz) and early (0-10 ms) auditory evoked potentials (EAEP) evoked by chicks were recorded on 68 newborn babies (premature or at term), infants and children, some with central nervous system or psychiatric disorders, who had normal or impaired hearing. MLR were obtained either during sleep, chloral-hydrate sedation or ketamine anesthesia. Thresholds estimated from MLR and EAEP were compared to those from subsequent psychoacoustic pure tone testing. We confirm that MLR provide good threshold estimates for hearing in the low frequency range, whereas click evoked EAEP are good threshold indicators only for high frequencies.

Isolation and expression of the Pneumocystis carinii dihydrofolate reductase gene

Pneumocystis carinii dihydrofolate reductase (DHFR; 5,6,7,8-tetrahydrofolate: NADP+ oxidoreductase, EC 1.5.1.3) cDNA sequences have been isolated by their ability to confer trimethoprim resistance to Escherichia coli. Consistent with the recent conclusion that P. carinii is a member of the Fungi, sequence analysis and chromosomal localization show that DHFR is neither physically nor genetically linked to thymidylate synthase. Expression of recombinant P. carinii DHFR in heterologous hosts provides an abundant source of the enzyme that may form a basis for the development of new therapies for this enigmatic pathogen. Studies with the recombinant enzyme show that trimethoprim is a very poor inhibitor of P. carinii DHFR and, in fact, is a more potent inhibitor of human DHFR.

Enhancing effects of immunoactive peptide FR48217 on immunological responses to vaccination by inactivated influenza virus

The adjuvant effect of an immunoactive peptide, FR48217 (FR), was investigated in mice vaccinated with inactivated influenza virus with and without FR (designated as V + FR and V - FR, respectively). Mice were infected with influenza virus A/PR/8/34 28 days after vaccination. The survival rate indicated a strong adjuvant effect of FR on vaccination with inactivated influenza virus. No difference in interferon activity in the pulmonary lavage fluid was found between the V + FR and V - FR groups. The titres of virus-specific IgA and IgG antibodies in the serum increased after vaccination in both V + FR and V - FR groups and were significantly higher in the V + FR group than in the V - FR group. On days 2 and 4 after viral infection, the serum antibody titres decreased sharply and then increased again rapidly. The free IgA and IgG antibody levels in the pulmonary lavage fluid of vaccinated mice started to increase after day 4. It is proposed that one of the mechanisms by which FR has the adjuvant effect on vaccination is the increase of virus-specific IgA and IgG antibodies in the serum, which are diffused into the infection sites of the epithelial tissues in the respiratory tract to neutralize the virus at the early stages of viral infection.

Rapid detection of cutaneous herpes simplex virus infection with the polymerase chain reaction

A simple and specific method for detecting herpes simplex virus infection in routinely processed paraffin-embedded biopsy specimens is described. DNA is extracted from paraffin blocks, and subjected to DNA amplification with the polymerase chain reaction. After 40 rounds, an amplified band can be detected after agarose gel electrophoresis and ethidium bromide staining. This band is specific for herpes simplex virus, because tissues infected with related viruses do not give this amplified band. We have been able to detect viral DNA in small punch skin biopsies with this procedure, which can take as little as 6 h.

Localization of cytomegalovirus DNA in plastic-embedded sections by in situ hybridization. A methodologic study

The use of in situ hybridization for the identification of specific nucleic acid sequences in tissue sections has the potential for broad application in pathology. Although this technique has been successfully applied to routine paraffin sections, there have been few studies of the application of in situ hybridization to plastic-embedded tissue sections. The authors adapted techniques developed for paraffin sections to take advantage of the potential for improved morphology and more precise localization inherent in the plastic sections. A commercially available biotinylated DNA probe specific for the cytomegalovirus to develop a practical method for detection of nucleic acid sequences in plastic-embedded tissues was used. Using plastic sections, cytomegalovirus DNA sequences could readily be identified with precise localization of the virus and superb histology.

Resolution of brain edema in severe brain injury at controlled high and low intracranial pressures

A series of 87 patients with severe brain injury were studied. Intracranial pressure (ICP) monitoring and external ventricular drainage were used to control ICP at high and low levels. Clearance of ytterbium-169-labeled diethylenetriaminepentaacetic acid (169Yb-DTPA), Evans blue dye, and ventricular cerebrospinal fluid protein was measured at the two ICP levels over consecutive periods of 4 hours to confirm clearance of brain edema. The results support the hypothesis that brain edema is in part absorbed in the cerebrospinal fluid via transventricular flow.