The interactions of the N-terminal fusogenic peptide of HIV-1 gp41 with neutral phospholipids

We have studied the interactions with neutral phospholipid bilayers of FPI, the 23-residue fusogenic N-terminal peptide of the HIV-1LAI transmembrane glycoprotein gp41, by CD, EPR, NMR, and solid state NMR (SSNMR) with the objective of understanding how it lyses and fuses cells. Using small unilamellar vesicles made from egg yolk phoshatidylcholine which were not fused or permeabilised by the peptide we obtained results suggesting that it was capable of inserting as an alpha-helix into neutral phospholipid bilayers but was only completely monomeric at peptide/lipid (P/L) ratios of 1/2000 or lower. Above this value, mixed populations of monomeric and multimeric forms were found with the proportion of multimer increasing proportionally to P/L, as calculated from studies on the interaction between the peptide and spin-labelled phospholipid. The CD data indicated that, at P/L between 1/200 and 1/100, approximately 68% of the peptide appeared to be in alpha-helical form. When P/L = 1/25 the alpha-helical content had decreased to 41%. Measurement at a P/L of 1/100 of the spin lattice relaxation effect on the 13C nuclei of the phospholipid acyl chains of an N-terminal spin label attached to the peptide showed that most of the peptide N-termini were located in the interior hydrocarbon region of the membrane. SSNMR on multilayers of ditetradecylphosphatidyl choline at P/Ls of 1/10, 1/20 and 1/30 showed that the peptide formed multimers that affected the motion of the lipid chains and disrupted the lipid alignment. We suggest that these aggregates may be relevant to the membrane-fusing and lytic activities of FPI and that they are worthy of further study.

Evaluation of a fluorescence-polarization assay for the diagnosis of bovine brucellosis in México

A homogeneous fluorescence-polarization assay (FPA) was used for the serological diagnosis of bovine brucellosis in México. The assay uses O-polysaccharide prepared from Brucella abortus lipoplysaccharide (20-30 kDa) conjugated with fluorescein isothiocyanate as a tracer. To measure the fluorescence polarization, a FPM-1 fluorescence-polarization analyzer was used with the procedure described by Nielsen et al. (1996b). A cut-off value of 90 millipolarization (mP) units was used for testing 560 bovine sera from different areas of México. (305 positive sera and 255 negative sera according to the complement fixation test; CFT.) Some were tested with the Rose Bengal plate (RB) test (n = 490) and some with the rivanol-agglutination (RIV) test (n = 190). Sensitivities were 98.3%, 99.3% and 99.0%, and specificities were 68.8%, 55.4% and 96.9%, respectively, for RB, RIV and FPA. The FPA gave a kappa coefficient of agreement with respect to CFT of 0.96, while RB and RIV (relative to the CFT) gave coefficients of 0.70 and 0.61, respectively. Finally, ROC analysis suggested a cut-off value which agreed with the one recommended in the test procedure. We concluded that FPA is a suitable test to be used instead of the CFT in Mexican conditions.

Treatment of human immunodeficiency virus 1-infected infants and children with the protease inhibitor nelfinavir mesylate

An open-label study was conducted of nelfinavir mesylate, given with reverse transcriptase inhibitors to human immunodeficiency virus 1 (HIV-1)-infected infants and children 3 months to 13 years of age. Doses of nelfinavir mesylate of 20-30 mg/kg yielded drug exposures comparable to those seen in adults. The drug was well tolerated; mild diarrhea was the primary toxic effect observed. Seventy-one percent (39) of the 55 evaluable subjects had an initial decrease in plasma HIV-1 RNA, of at least 0.7 log10 copies/mL; suppression of plasma HIV-1 RNA levels to < 400 copies/mL was observed in 15. Children who began taking at least one new reverse transcriptase inhibitor near the time when nelfinavir mesylate was started, and those with a > or = 24% proportion of CD4 lymphocytes, had a greater chance of achieving and maintaining a decline in plasma HIV-1 RNA to < 400 copies/mL. Suppression of viremia was achieved in children as young as 3 months of age.

Urethral epithelial cells on the surface on hydrophilic catheters after intermittent catheterization: cross-over study with two catheters

AIM

To count the number of cells on the surface of the two commercial hydrophilic catheters, Lofric and EasiCath used for intermittent catheterization (IC) after 30-60 s in water without the necessity of catheter jelly.

PARTICIPANTS

Twenty spinal cord lesioned (SCL) individuals. Six were women, and 14 men.

METHODS

IC was performed on average five times a day (range: 4-10). In a randomised cross-over design all catheterizations were performed either with Lofric or EasiCath in two consecutive 24 h periods. The catheter used for the last catheterization in each 24 h period was fixed, and divided into pieces of 5 cm. From each of these a piece with the length of 5 mm was taken for surface microscopy after staining. The total number of cells was counted without knowledge of the type of catheter. According to the fractionator principle an unbiased estimate of the total number of cells on the surface of the cateter was calculated.

RESULTS

There was no difference in the number of urethral epithelia cells on the catheters. No granulocytes were identified. The number of cells identified on the catheters were from 30 to > 10 000. No differences related to age, level of SCL, ASIA impairment scale, months since SCL or type of IC were found. There was a trend that women had higher cell counts than men.

CONCLUSION

No difference was found regarding number of urethral epithelial cells on the surface of the catheters after catheterization. This indicates no difference in urethral trauma between the two catheters.

Prophylactic use of alfacalcidol in corticosteroid-induced osteoporosis

One hundred and forty-five patients suffering from diseases requiring long-term treatment with high doses of corticosteroids (30 mg/day or greater of prednisolone) were recruited to the study. Patients had to be steroid naive on entry to the study (not more than 15 days of treatment with a corticosteroid within the previous 24 months). Patients were randomized to receive either 1 microgram/day alfacalcidol or placebo capsules for 12 months. Bone mineral density (BMD) of the lumbar spine was assessed by dual-photon absorptiometry on entry and after 3, 6 and 12 months' treatment. Safety was monitored by the recording of all adverse events reported by patients and the regular screening of blood samples for hematology and serum biochemistry. Of the 145 patients, 74 were randomized to alfacalcidol and 71 to placebo. The treatment groups were well matched at baseline with no significant differences in demographic, clinical or biochemical parameters. The mean equivalent dose of prednisolone at baseline was 46.6 mg/day and 46.3 mg/day for the alfacalcidol and placebo group respectively. From the 145 patients randomized to treatment, 71 (38 who received alfacalcidol and 33 who received placebo) provided BMD data both at baseline and at 3, 6 and 12 months. The percentage change in BMD after 6 months' treatment was -2.11% in the alfacalcidol group and -4.00% in the placebo group (p = 0.39). After 12 months the percentage change in BMD was +0.39% (CI: -4.28 to 4.81) in the alfacalcidol group and -5.67% (CI: -8.13 to -3.21) in the placebo group, this difference (6.06%, CI: 0.88 to 11.24) being statistically significant (p = 0.02). An intention to treat analysis also showed a significant difference between the two treatment groups in alfacalcidol's favor (3.81%, p = 0.01; CI: 0.92 to 6.70). There was no significant difference between the two treatment groups in the corticosteroid dose at any time point during the study. Serum calcium was measured throughout and there were no significant differences between the two treatment groups at any visit. This study suggests that alfacalcidol can prevent corticosteroid-induced bone loss from the lumbar spine. Long-term use of alfacalcidol was not associated with any significant adverse effects in this diverse group of patients.

Diagnosis of bovine brucellosis using a homogeneous fluorescence polarization assay

To evaluate the fluorescence polarization assay (FPA) for the serological diagnosis of bovine brucellosis, 118 sera from cattle which were culture positive for Brucella abortus, 1751 sera from cattle from premises containing cattle infected with B. abortus, 1222 sera from cattle vaccinated with B. abortus strain 19 and 1199 sera from cattle with no evidence of brucellosis were tested in Argentina, Chile, Mexico and in the American states of Iowa, Missouri and Texas. Initial determination of serological positivity and negativity was based upon reactivity in currently used serological tests, consisting of a rapid screening test, the rose-bengal or the buffered plate antigen tests, followed by a second serological test, the complement fixation test. Sensitivity of the FPA (sera from culture positive animals) ranged from 87.5% to 100%. Serological positivity of cattle from infected premises ranged from 65.5% to 99.0% while the % negative cattle in herds without evidence of brucellosis was between 94.9 and 100%. Of B. abortus strain 19 vaccinated cattle which were positive in at least one in-use serological tests, 88.2% were negative in the FPA. In contrast, previous Canadian studies, sensitivity values were 99.0% and 100% and the specificity in both cases was 100%. This discrepancy was probably due to the use of less well characterized sera in the current study.

Experimentally induced nasal hypersecretion does not reduce the efficacy of intranasal levocabastine

In allergic rhinitis, a nasal H1-antihistamine spray seems to be well suited for usage on an as-needed basis, because it has a quick onset of action, and many patients prefer to take medicine only when they have symptoms. It is a prerequisite, however, that nasal hypersecretion during a rhinitis episode does not significantly reduce the efficacy of intranasal treatment by washing away the drug before it reaches the H1-histamine receptors. In order to investigate this problem, we have induced nasal hypersecretion with a methacholine challenge in one experiment and in four experiments we have washed the nasal cavities 0.5 min. before, 5 min. before, 0.5 min. after and 5 min. after intranasal use of the H1-antagonist, levocabastine. The symptom response to a subsequent histamine challenge was used as the effect parameter. Levocabastine reduced the number of histamine-induced sneezes with 81% (p < 0.0001) and the secretion weight with 62% (p < 0.001) compared with placebo. Neither methacholine-induced hypersecretion nor washing the nose with saline reduced the efficacy of the antihistamine spray. We conclude that experimentally induced nasal hypersecretion does not reduce the efficacy of the antihistamine spray, and probably the same applies to rhinorrhea during an acute episode of allergic rhinitis.

Standardization of smooth lipopolysaccharide preparations for use in diagnostic serological tests for bovine antibody Brucella abortus

A procedure for standardizing Brucella abortus smooth lipopolysaccharide used in diagnostic tests for brucellosis is proposed. The procedure is based on the reactivity of antigen preparations with a panel of sera with or without antibody to B. abortus using a set of parameters established with 13 antigen preparations. For each serum dilution, a mean and two standard deviations were calculated in the indirect and competitive enzyme immunoassays. If data obtained with an antigen preparation, using the same serum dilutions, falls within the range established using two standard deviations, the antigen would be considered acceptable for diagnostic use.

Variability of serum antibody responses of goat kids to a commercial Clostridium perfringens epsilon toxoid vaccine

Twenty-nine Angora goats were used in a trial of a commercial enterotoxaemia (pulpy kidney disease) vaccine. The animals were allocated to four groups, of which three received an initial dose of vaccine, two also received a booster of the same vaccine either 28 or 42 days after the first vaccination, and the fourth remained as an unvaccinated control group. An indirect ELISA technique was used to measure the titres of Clostridium perfringens type D epsilon antitoxin in serum samples taken before vaccination and 17, 28, 42, 59, 70, 86, 98 and 128 days after vaccination. There was a wide range of antibody titres after vaccination, and the great majority of the vaccinated animals had titres below the protective level, arbitrarily set at 0.25 iu/ml, by day 98.

Ciliary neurotrophic factor potentiates the beta-cell inhibitory effect of IL-1beta in rat pancreatic islets associated with increased nitric oxide synthesis and increased expression of inducible nitric oxide synthase

Proinflammatory cytokines are implicated as effector molecules in the pathogenesis of IDDM. Interleukin-6 (IL-6) alone or in combination with IL-1beta inhibits glucose-stimulated insulin release from isolated rat pancreatic islets by unknown mechanisms. Here we investigated 1) if the effects of IL-6 are mimicked by ciliary neurotrophic factor (CNTF), another member of the IL-6 family of cytokines signaling via gp130, 2) the possible cellular mechanisms for these effects, and 3) if islet endocrine cells are a source of CNTF. CNTF (20 ng/ml) potentiated IL-1beta-mediated (5-150 pg/ml) nitric oxide (NO) synthesis from neonatal Wistar rat islets by 31-116%, inhibition of accumulated insulin release by 34-49%, and inhibition insulin response to a 2-h glucose challenge by 31-36%. CNTF potentiated IL-1beta-mediated NO synthesis from RIN-5AH cells by 83%, and IL-1beta induced islet inducible NO-synthase (iNOS) mRNA expression fourfold. IL-6 (10 ng/ml) also potentiated IL-1beta-mediated NO synthesis and inhibition of insulin release, whereas beta-nerve growth factor (NGF) (5 or 50 ng/ml) had no effect. mRNA for CNTF was expressed in rat islets and in islet cell lines. In conclusion, CNTF is constitutively expressed in pancreatic beta-cells and potentiates the beta-cell inhibitory effect of IL-1beta in association with increased iNOS expression and NO synthesis, an effect shared by IL-6 but not by beta-NGF. These findings indicate that signaling via gp130 influences islet NO synthesis associated with iNOS expression. We hypothesize that CNTF released from destroyed beta-cells during the inflammatory islet lesion leading to IDDM may potentiate IL-1beta action on the beta-cells.

Combination laser conization as treatment of microinvasive carcinoma of the uterine cervix

During the period June 1985 to August 1992 combination laser conization was considered definite therapy in 41 patients with microinvasive carcinoma of the cervix. Selection criteria for conservative, fertility-saving therapy were: invasion 3 mm or less, no lymphovascular involvement and horizontal spread of 7 mm or less. After treatment patients were followed for 5 to 12 years, mean follow-up 81 months, and mean number of examination was 10. In one cases, adenocarcinoma in situ was diagnosed during follow-up. In all other cases persistent or recurrent disease was not diagnosed during follow-up. By thorough histopathologic evaluation and strict criteria for selection of patients, it was possible to perform conservative treatment with no observed risk of undertreatment. Combination laser conization was a useful treatment modality. A follow-up regimen based on colposcopy and cytology proved sufficient.

Evaluation of an indirect ELISA for the diagnosis of bovine brucellosis in milk and serum samples in dairy cattle in Argentina

An indirect enzyme-linked immunosorbent assay (ELISA) for Brucella abortus antibodies detection in bovine milk and serum samples was validated. The assay use B. abortus smooth lipopolysaccharide as antigen, immobilized on a polystyrene matrix; milk diluted 1:2 or serum diluted 1:50, in a buffer containing divalent cation chelating agents EDTA and EGTA (ethyleneglycol-bis-aminoether-N,N,N',N'-tetraacetic acid) to reduce non-specific reactions; and a mouse monoclonal antibody specific for an epitope of bovine IgG1, conjugated with horseradish peroxidase. A total of 2646 sera and 2119 milk samples from cows older than 24 months were obtained from 12 brucellosis-free herds for at least the previous 5 years. Milk samples were obtained in parallel with serum samples. The remaining 527 serum samples were from dry cows. All cattle were vaccinated with B. abortus strain 19 between 3-10 months of age. Five hundred and fifty-two milk samples and 562 serum samples were obtained from 6 infected herds with abortions where B. abortus was isolated at least once no more than 6 months before sampling. The complement-fixation test (CFT) on serum samples was considered the gold standard. Serum samples were also tested with the official screening test: the buffered plate antigen (BPA) test. The cut-off point was determined using receiver-operating characteristic (ROC) analysis. For milk samples, it was fixed at 36 percent positivity (PP) giving a sensitivity of 99.6% with a 95% confidence interval (CI) of 98.6-99.9%. The specificity was 99.1% (CI 98.9-99.4%). For serum samples, the cut-off was fixed at 53 PP giving a sensitivity of 99.6% (CI 98.6-99.9%) and a specificity 98.6% (CI 98-99%). The BPA test showed a relative sensitivity of 99.6% (CI 98.6-99.9%) and a relative specificity of 98.6% (CI 98.1-99%). Our results indicate that the indirect ELISA is a highly sensitive and specific test and can be adapted to process a large number of samples.

Enzyme immunoassays for serological diagnosis of bovine brucellosis: A trial in Latin America

The results of a field trial conducted in Latin America with two indirect enzyme-linked immunosorbent assays (ELISAs) and two competitive ELISAs (CELISAs) for the detection of bovine antibody to Brucella abortus are reported. One of the CELISA formats performed most accurately. The percentage of positive reactions in the CELISA relative to the selected positive rose bengal agglutination test (RBT) and complement fixation test (CFT) results was 97.47%, the percentage of negatives relative to the selected negative RBT and CFT results for unexposed cattle was 98.32%, and the percentage of negatives in cattle vaccinated with B. abortus 19 was 96.51%. The same assay format under Canadian conditions had an actual sensitivity of 100%, a specificity of 99.90% in nonvaccinates, and a specificity of 97.7% in a strain 19-vaccinated population. Overall, the CELISA performed as expected and the results were not dissimilar from the results obtained in the Canadian study. This provided further evidence that this CELISA can in many instances differentiate infected cattle from those that are vaccinated or infected with a cross-reacting organism while still giving very few false-positive or false-negative results.

Characterization of proteins utilized in the desulfurization of petroleum products by matrix-assisted laser desorption ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI/TOF/MS) with delayed extraction is utilized in linear, reflected-ion and post-source decay (PSD) modes to directly characterize enzymes being developed for use in a petroleum desulfurization process. The DNA sequence for the genes isolated from Rhodococcus sp. strain IGTS8 that produce three of the four enzymes under study had been previously reported with a discrepancy in residue assignments for one of the enzymes, dsz-C. The use of proteolytic digests followed by MALDI/TOF/MS with delayed extraction in the reflected-ion mode provided sequence-specific information with mass accuracies exceeding 40 ppm over a range of masses and signal-to-noise values. Peptide mapping of >80% of the residues was accomplished for all four proteins. The use of PSD established the true sequence for dsz-C, resolving the discrepancy in the literature. A posttranslational loss of N-terminal methionine was observed for each of the four proteins in linear MALDI/MS and was reconfirmed by peptide mapping for three of the proteins.

The effects of exogenous epidermal growth factor on the developing urinary tract in rats: a stereological description

Systemic treatment with epidermal growth factor (EGF) induces growth of all wall layers of the urinary tract in pigs and rats. In this study, we describe the time-dependent growth of the ureter and bladder. Forty-eight female Wistar rats were allocated into five groups receiving EGF treatment (150 microg/kg per day) for 0 (controls), 1, 2, 3 or 4 weeks before being killed. The 24-h urine excretion was increased only in the group treated for 4 weeks with EGF. Measured by a simple infusion device, EGF significantly increased the bladder capacity by more than 50% in all the EGF-treated groups. The volumes of the wall layers of the ureter and bladder were quantified using stereology. After 4 weeks of treatment with EGF, the total volumes of the ureter and bladder were 1.8- and 2.1-fold larger than in the control group (the urothelium was 2.8- and 3.5-fold larger and the muscular coat 1.6- and 1.6-fold larger in the ureter and bladder, respectively). In conclusion, the EGF-induced growth of the urinary tract is characterized by increased bladder capacity, and increased volume of all wall layers --most prominently the urothelium.

Interaction of lipophilic ions with the plasma membrane of mammalian cells studies by electrorotation

The electrical properties of biological and artificial membranes were studied in the presence of a number of negatively charged tungsten carbonyl complexes, such as [W(CO)5(CN)]- , [W(CO)5(NCS)]-, [W2(CO)10(CN)]-, and [W(CO)5(SCH2C6H5)]-, using the single-cell electrorotation and the charge-pulse relaxation techniques. Most of the negatively charged tungsten complexes were able to introduce mobile charges into the membranes, as judged from electrorotation spectra and relaxation experiments. This means that the tungsten derivatives act as lipophilic anions. They greatly contributed to the polarizability of the membranes and led to a marked dielectric dispersion (frequency dependence of the membrane capacitance and conductance). The increment and characteristic frequency of the dispersion reflect the structure, environment, and mobility of the charged probe molecule in electrorotation experiments with biological membranes. The partition coefficients and the translocation rate constants derived from the electrorotation spectra of cells agreed well with the corresponding data obtained from charge-pulse experiments on artificial lipid bilayers.

Sustained oscillations in glycolysis: an experimental and theoretical study of chaotic and complex periodic behavior and of quenching of simple oscillations

We report sustained oscillations in glycolysis conducted in an open system (a continuous-flow, stirred tank reactor; CSTR) with inflow of yeast extract as well as glucose. Depending on the operating conditions, we observe simple or complex periodic oscillations or chaos. We report the response of the system to instantaneous additions of small amounts of several substrates as functions of the amount added and the phase of the addition. We simulate oscillations and perturbations by a kinetic model based on the mechanism of glycolysis in a CSTR. We find that the response to particular perturbations forms an efficient tool for elucidating the mechanism of biochemical oscillations.

Use of dried smooth lipopolysaccharide antigen coated polystyrene plates for diagnosis of bovine brucellosis by enzyme immunoassay

Polystyrene plates (96 well) were sensitized with Brucella abortus smooth lipopolysaccharide (SLPS) antigen and then air dried at room temperature (RT) for about 1 hour to dry. Dryness was judged complete when a buffer meniscus was absent from the bottom of the well. The plates were resealed kept on the bench at RT for the duration of the study. Testing was done over 13 months by competitive and indirect ELISAs (C- and IELISA) for bovine antibody to B. abortus using panels of sera from B. abortus S19 vaccinated, unexposed and infected cattle. Testing revealed that consistent results were obtained over the test period suggesting that air drying may be a suitable alterative for storage of plates sensitized with some antigens, in particular, smooth lipopolysaccharide.

Identification of a 35-kilodalton serovar-cross-reactive flagellar protein, FlaB, from Leptospira interrogans by N-terminal sequencing, gene cloning, and sequence analysis

During the screening of antibodies to pathogenic leptospires, a murine monoclonal antibody (designated M138) was found to react with various serovars. An antigen of approximately 35 kDa from Leptospira interrogans serovar pomona, which reacted strongly with M138, was characterized by N-terminal amino acid sequencing and identified as a flagellin, a class B polypeptide subunit (FlaB) of the periplasmic flagella. The gene encoding the FlaB protein, flaB, was amplified from the genomic DNA of several pathogenic serovars by PCR with a single pair of oligonucleotide primers, suggesting that FlaB is highly conserved among these serovars. Cloning and sequence analysis of flaB from serovar pomona revealed that it contains an 849-bp open reading frame with a G + C content of 46.88% which encodes a 283-amino-acid protein with a calculated molecular mass of 31.297 kDa and a predicted pI of 9.065. A sequence comparison of flagellin proteins revealed that the amino acid sequence is most variable in the central portion of the serovar pomona FlaB, which is believed to contain specific sequence information and which may thus be useful in the design of DNA or synthetic peptide probes suitable for the detection of infection with pathogenic leptospires.

Detection of Clostridium perfringens type D epsilon antitoxin in serum of goats by competitive and indirect ELISA

Indirect and competitive ELISA techniques were developed and their ability to detect antibodies to Clostridium perfringens epsilon toxin in goat serum was compared. Different dilutions of a hyperimmune goat serum, in serum from a colostrum-deprived kid, were used as positive controls, while sera from eleven colostrum-deprived kids were used as negative controls. The epsilon toxin antibodies in the hyperimmune serum were also measured by mouse neutralisation test (MNT). The correlation coefficient between both the indirect ELISA technique and MNT was 0.99, while the same coefficient for the competitive ELISA was 0.98. Both the indirect and competitive ELISAs proved to be rapid, simple, sensitive and specific for detecting antibodies to C. perfringens epsilon toxin in serum of goats.