A wireless beta-microprobe based on pixelated silicon for in vivo brain studies in freely moving rats

The investigation of neurophysiological mechanisms underlying the functional specificity of brain regions requires the development of technologies that are well adjusted to in vivo studies in small animals. An exciting challenge remains the combination of brain imaging and behavioural studies, which associates molecular processes of neuronal communications to their related actions. A pixelated intracerebral probe (PIXSIC) presents a novel strategy using a submillimetric probe for beta(+) radiotracer detection based on a pixelated silicon diode that can be stereotaxically implanted in the brain region of interest. This fully autonomous detection system permits time-resolved high sensitivity measurements of radiotracers with additional imaging features in freely moving rats. An application-specific integrated circuit (ASIC) allows for parallel signal processing of each pixel and enables the wireless operation. All components of the detector were tested and characterized. The beta(+) sensitivity of the system was determined with the probe dipped into radiotracer solutions. Monte Carlo simulations served to validate the experimental values and assess the contribution of gamma noise. Preliminary implantation tests on anaesthetized rats proved PIXSIC's functionality in brain tissue. High spatial resolution allows for the visualization of radiotracer concentration in different brain regions with high temporal resolution.

[A comparative study of nocturnal sleep duration and timetable of children between five- and ten-years-old according to their age and socio-economic environment]

AIM

This study was conducted on a sample of 644 pupils between the ages of five and ten years at school in the Orléans-Tours education authority with the aim of studying the nocturnal sleep duration and timetable of young children according to age and socio-economic environment.

METHOD

In order to find out about children's sleeping habits (duration, time of going to bed and getting up, and weekly variations) a standard grid was used to carry out a cross-sectional survey in the children's families. This was filled in each day from Monday to Sunday during the same school week for all the children.

RESULTS

Sleep duration decreased with age from maternelle to CM2 (nursery to last year of primary education). Data relating to sleep duration from CE2 (third year of primary school - 8-year-old -) showed differences according to whether the school belonged to an Educational Priority Zone (EPZ) or not. It was noticed that between five- and ten-year-old children from EPZ lost 62 minutes of sleep, whereas those not from EPZ only lost 29 minutes. These results would suggest that in addition to developmental factors, environmental factors also play a role in sleep duration. The differences observed were due to later bed times for children from EPZ. Weekly variations in sleep were generally very similar for all the children. At the weekend all the children tended to go to bed later, however this was more noticeable Saturday night for children not living in EPZ. Children slept the longest on Tuesday night due to the fact they got up later Wednesday morning (Wednesday is a day off in the majority of French schools). However, children from the age of nine (CM1 - forth year of primary education -) in EPZ did not benefit from this recuperation time, as they went to bed later but still got up early the next morning.

CONCLUSION

This study showed that in addition to the physiological and developmental factors that influence children's sleep, the socio-economic context also plays a role. These results as a whole highlight the importance that practitioners and families should pay to maintaining a regularity in the child's routine and in the amount of sleep necessary at each age.

implication of the structure of the Helicobacter pylori cag pathogenicity island in induction of interleukin-8 secretion

Helicobacter pylori virulence is associated with the presence of the cag pathogenicity island (PAI). The cag PAI is involved in the ability to induce interleukin-8 (IL-8) secretion by human cells, which is implicated in the inflammatory response of the gastric mucosa to H. pylori infection. The aim of this study was to determine whether the genetic structure of the cag PAI is conserved and whether it is linked to IL-8 induction ability. Detection of specific markers (cagA, picB, cag13-cag14, virD4, and IS605) by PCR and dot blot hybridization and long-distance PCR determination of the presence of cagI, cagII, and the middle region of the cag PAI were performed on 153 strains isolated from adults suffering from ulcers (n = 79) or gastritis (n = 74). IL-8 induction ability was evaluated by coculture of the strains with HEp-2 cells. Eighty-three strains (54.3%) had an entire cag PAI, 12 strains (7.8%) had the cag PAI split in two, 49 strains (32%) had no cag PAI, and 9 strains exhibited other structural combinations. The presence of an entire cag PAI was statistically correlated with the presence of IS605 (P = 0.006) and the ability to induce IL-8 secretion but not with clinical presentation of the infection. The structure of the cag PAI appears to be rather conserved and is related to the proinflammatory power of a strain. The existence of strains inducing IL-8 secretion regardless of the cag PAI structure suggests that this region is not the only requirement for IL-8 secretion.

Antibody response of patients with Helicobacter pylori-related gastric adenocarcinoma: significance of anti-cagA antibodies

The aim of this study was to search for a specific antibody pattern in sera from patients suffering from Helicobacter pylori-related gastric adenocarcinoma (GAC). The serological response of 22 patients suffering from GAC, 31 patients with gastroduodenal ulcer, and 39 asymptomatic subjects was analyzed using immunoblotting performed with three H. pylori strains: strain ATCC 43579; strain B110, isolated from a patient with ulcers; and strain B225, isolated from a patient with GAC. In addition, the latex agglutination test Pyloriset Dry was used to analyze ambiguous sera. H. pylori seropositivity was 75% in the GAC group, 61.3% in the ulcer group, and 56.4% in the asymptomatic group. Anti-CagA antibodies were found more often in the GAC group (48.8%) and in the ulcer group (47.3%) than in the asymptomatic group (21.2%). These percentages depended on the strain used as an antigen: in the GAC group, the anti-CagA frequencies were 93.3, 40, and 13.3% with strains B225, B110, and ATCC 43579, respectively. Thus the presence of anti-CagA antibodies was increased in patients suffering from H. pylori-related GAC, in particular when the CagA antigen was from a GAC strain. These data suggest the existence of a CagA protein specifically expressed by H. pylori strains isolated from GAC patients.

Correlation between IL-8 induction, cagA status and vacA genotypes in 153 French Helicobacter pylori isolates

The polymorphism of clinical presentations associated with Helicobacter pylori infection is potentially due to differences in the virulence of individual strains. H. pylori virulence has been associated with the ability to induce secretion of interleukin-8 (IL-8), the vacA genotypes, and the cagA status. The aim of this study was to determine the virulence profiles of 153 French H. pylori isolates on the basis of vacA genotypes, cagA status, and IL-8 induction ability. A total of 153 H. pylori isolates from patients with chronic gastritis (n = 74) or gastro-duodenal ulcers (n = 79) was examined for vacA genotypes and cagA status by polymerase chain reaction (PCR) and dot blot, and for their ability to induce IL-8 secretion by HEp-2 cells. The prevalence of vacA genotypes was: s1/m1 44.3%, s1/m2 24.9%, and s2/m2 23.5%. The cagA gene was present in 64% of the strains. IL-8 secretion was induced by 58.7% of the isolates. The presence of the cagA gene was significantly correlated with the s1/m1 vacA genotype and with the induction of IL-8. Thirty-four strains were atypical (cagA-positive/IL-8 noninducer or cagA-negative/IL-8 inducer). vacA genotypes, cagA status, and IL-8 induction ability are not correlated with the presence or absence of ulcer. The cagA status is not sufficient to predict the proinflammatory ability of H. pylori.

Immunogens of interest for the diagnosis of Campylobacter jejuni infections

In order to identify the C. jejuni immunogens of interest for the diagnosis of Campylobacter infections, we analyzed the humoral response of 153 patients by using complement fixation (CF) and western blot assays. A first group of 79 sera was from C. jejuni infected patients suffering from enteritis (n=16), Guillain-Barré syndrome (GBS) (n=40) and arthritis (n=23). A second group of 49 sera was from healthy blood donors and a third group consisted of 25 sera from children under 4 years old. Using the CF test, 88.6% of the C. jejuni infected patients were seropositive versus 28.5% of the healthy blood donors and none of the children. The Western blot assay allowed detection of antibodies directed against seven selected antigens ranging from 14 to 67 kDa. Three of these antigens with a molecular size of 29, 37 and 43 kDa were detected by 86.0%, 84.8% and 91.1% of the C. jejuni infected patients, respectively. These three antigens seem to be good candidates for the development of assays suitable for direct and indirect diagnosis of Campylobacter infections.

Phenotypic changes of Helicobacter pylori components during an experimental infection in mice

The bacterial pathogen Helicobacter pylori is highly adapted to the human stomach and the clinical isolates show a high diversity which could be due to adaptative changes of the strains passing from one host to another. In order to study these variations, experimental infection of mice was developed and provided three out of the eleven tested strains able to infect C57BL/6 mice: the Sydney strain which is known to be well adapted to mice and two freshly isolated strains from infected patients. Mice were orally infected with one of these three strains (infecting strains) and were killed 45 days later. H. pylori strains were isolated from the stomachs of mice (emerging strains). The three infecting strains were compared to the three emerging strains for protein and lipopolysaccharide profiles, antigenic profiles revealed by Western blot with monospecific sera and genetic status by testing for the cagA gene and the vacA genotype. During the 45 days of infection, H. pylori underwent phenotypic variations which may be attributed to the adaptation from a human to a mouse environment or from an in vitro to a mouse environment. Those variations consisted of an over-expression at the cell surface of a 180-kDa protein and of a decreased expression of proteins of 260 and 120 kDa. Moreover, antigenic variations were shown for the two freshly isolated strains from human: the CagA and VacA antigens were in the saline extracts of the infecting strains only while the UreA, UreB, HspA and HspB were in the saline extracts of both the infecting and the emerging strains. These variations may contribute to the adaptation of the strains to the mouse environment.

Effects of caffeine on lipoprotein lipase gene expression during the adipocyte differentiation process

In this study, the effects of caffeine on lipoprotein lipase (LPL) gene expression were investigated in the 3T3-F442A preadipocyte cell line during the adipocyte differentiation process by determining LPL enzymatic activity and its messenger RNA (mRNA) level. The results demonstrate that caffeine acts on the gene expression of LPL, an early marker of adipocyte differentiation. It has a biphasic action: it increases gene expression in terms of mRNA when it is added to preadipocytes during the early stage of differentiation, but this is accompanied by a reduction of enzymatic activity. On the other hand, when caffeine is added for long periods during differentiation and/or when it is added to mature adipocytes, it induces marked inhibition of mRNA levels, correlated with a marked reduction of secreted enzymatic activity. The inhibitory effect of caffeine on LPL mRNA level can be reproduced by theophylline, a phosphodiesterase inhibitor, and by dibutyryl cyclic AMP, a non-metabolizable analog of cyclic AMP. However, the effect of caffeine and theophylline lasts longer than that of cyclic AMP, suggesting that a mechanism other than inhibition of cyclic AMP hydrolysis may be involved in the action of caffeine.

Characterization and gene sequencing of a 19-kDa periplasmic protein of Campylobacter jejuni/coli

In order to study a 19-kDa protein (p19) of Campylobacter jejuni, we purified this protein to homogeneity from C. jejuni strain 81,176 by anion exchange chromatography. The molecular weight of the native protein is 19,000 daltons. P19 was found to be acidic with an isoelectric point of 4.8 and was located in the periplasmic space of the bacteria. The 20 N-terminal amino acids were sequenced and no significant similarities with known proteins were shown. A monoclonal antibody showed that p19 is conserved in the 2 species C. jejuni and C. coli. Analysis of sera from 23 patients with a Campylobacter-related infection indicated that p19 is not immunogenic during natural infection in man. The gene encoding p19 was cloned and no strong homologies with known sequences were identified. The preparation of a knockout mutant in p19 will enable the investigation of the function of this cell wall component of Campylobacter.

Transcriptional regulation of apolipoprotein E expression by cyclic AMP

Incubation of HepG2 cells in the presence of dibutyryl cAMP (db-cAMP), a cell permeable analogue of cyclic AMP, or forskolin, an agent which elevates intracellular cAMP, resulted in a 50% decrease in apoE mRNA levels within 24 h. Results of nuclear run-on transcription assays showed that db-cAMP down-regulates apoE gene expression at the transcriptional level. By transfection analysis with a plasmid containing the -614/+804 human apoE gene fused to the secreted placental alkaline phosphatase (SPAP) reporter gene, we showed that the SPAP activity was decreased by 50% when HepG2 cells were incubated in the presence of db-cAMP or forskolin, indicating that this promoter region mediated this negative effect. In contrast, when the smaller fragment -200/+1 of apoE promoter was linked to the CAT reporter gene, db-cAMP treatment of HepG2 cells resulted in a 2-fold increase in CAT activity, suggesting that positive cAMP-responsive elements were present in the proximal apoE promoter. These data indicate that transcriptional modulation of apoE gene expression by agents known to elevate the intracellular cAMP level is complex and involves several negative and positive elements located in the -614 to +804 region of the apoE gene whose global effect is negative on apoE gene transcription.

B cell epitopes of HIV type 1 p24 capsid protein: a reassessment

The objective of the present study was to identify p24 antigenic domains recognized during natural human immunodeficiency virus type 1 (HIV-1) infection, the determination of the major epitopes of p24 having significant applications for both the improvement of diagnostic approaches and the development of vaccines. Reactivity of 20 HIV-1-infected patients and 8 HIV-1-negative patients was analyzed using an enzyme-linked immunosorbent assay (ELISA) developed with 45 overlapping synthetic pentadecapeptides, spanning amino acids 133 to 363 of HIV-1 p55gag precursor. Two peptides covering aa 178-192 and 288-302 of p55 were recognized by 40 and 45% of HIV-1 antibody-positive human samples, respectively. A peptide covering aa 272-322 of p55 was synthesized and recognized by most human sera in indirect ELISA. However, inhibition assays indicated that this sequence does not contain all of the immunodominant domains of p24 since it was not sufficient to block binding of human sera to whole p24. A three-dimensional model of p24 derived from the Mengovirus VP2 suggests that the two distant sequences recognized by human sera containing antibodies to HIV-1 could possibly be a part of a conformational epitope built up by two loops corresponding to aa 183-186 and 289-292.

Transcriptional regulation of apolipoprotein A-I expression in Hep G2 cells by phorbol ester

The regulation of apolipoprotein A-I (apo A-I) gene expression by 12-O-tetradecanoylphorbol 13-acetate (TPA) was investigated in the human hepatoma cell line Hep G2. TPA treatment decreased apo A-I mRNA levels in a time-dependent manner, by up to 50% versus control cells within 24 h. Nuclear run-on transcription assays demonstrated a transcriptional effect of TPA. Using transfection analysis with a plasmid construct containing the -1378/+11 apo A-I promoter fused to the secreted placental alkaline phosphatase (SPAP) reporter gene, we showed that the SPAP activity was decreased to 50% when Hep G2 cells were incubated in the presence of TPA. The inhibitory effect of TPA was still maintained when fragment -253 to -4 of apo A-I promoter was linked to the CAT reporter gene. These data indicate that transcriptional modulation of apolipoprotein A-I gene expression following phorbol ester treatment is transduced by gene elements located between -253 and -4 of the apo A-I promoter.

Thyroid hormone modulates apolipoprotein-AI gene expression at the post-transcriptional level in Hep G2 cells

Hyperthyroidism is associated with elevated plasma levels of apolipoprotein AI (apo AI). We have examined the effects of 3,3',-5-triiodothyronine on apo AI mRNA, transcription run-on activity, apo AI mRNA half-life, and the rate of protein synthesis in Hep G2 cells, to understand the molecular mechanism by which thyroid hormone regulates apo AI gene expression. Incubation with thyroid hormone increased the apo AI and apo AII mRNA concentrations twofold. Cycloheximide alone caused a significant increase in apo AI mRNA. Nuclear run-on assays indicate that thyroid hormone did not change the rate of the apo AI gene transcription at 6, 12 or 24 h, showing that thyroid hormone did not modulate apo AI gene transcription. Kinetic studies performed in the presence of actinomycin D showed that the half-life of apo AI mRNA was increased 2-3-fold by thyroid hormone over control cells. Thyroid hormone did not change the incorporation of [35S]methionine into immunoprecipitable apo AI. Pulse-chase experiments demonstrated that there was no change in the secretion and degradation rates of labeled apo AI in response to T3. This suggests that thyroid hormone does not affect the catabolism of apo AI (degradation or/and uptake) and that translation control strongly influences the regulation of apo AI gene expression. The stabilization of apo AI mRNA by thyroid hormone and its role in translation remain to be elucidated.

The modulation of apolipoprotein E gene expression by 3,3'-5-triiodothyronine in HepG2 cells occurs at transcriptional and post-transcriptional levels

The regulation of the synthesis and secretion of apolipoprotein E (apoE) is incompletely understood. This study examines the mechanisms responsible for regulating apoE gene expression in HepG2 cells by thyroid hormone (3,3'-5-triiodothyronine). The secretion rate of apoE was by thyroid hormone increased (1.5-1.8-fold) in pulse/chase experiments. Thyroid hormone doubled apoE mRNA concentration as determined by Northern-blot analysis. Inhibition of protein synthesis by cycloheximide increased the thyroid-hormone-induced stimulation of apoE mRNA. This suggests that the synthesis of new protein is not required for thyroid hormone to stimulate apoE mRNA. Actinomycin D was used to inhibit new transcription; there was a more rapid degradation of mature apoE mRNA in thyroid hormone-treated HepG2 cells than in control cells, suggesting that thyroid hormone acts post-transcriptionally to regulate apoE gene expression. Cycloheximide blocked the action of thyroid hormone, suggesting that thyroid hormone regulates the turnover of apoE mRNA via the synthesis of de novo protein. Nuclear run-on transcription assays demonstrated that thyroid hormone stimulated apoE gene transcription threefold in 24 h. These findings indicate that the expression of the apoE gene is controlled at both transcriptional and post-transcriptional loci by the thyroid hormone.

Immune response to synthetic peptides of hepatitis delta antigen

Hepatitis delta antigen (HDAg) is the only viral protein known to be expressed during hepatitis delta virus (HDV) infection. Detection of antibody to HDAg (anti-HD) is the usual method for diagnosis of HDV infection since viremia lasts only a few weeks. In an effort to identify the major epitopes recognized by humans during natural infection, four oligopeptides including residues 2 to 17 (SP1), 155 to 172 (SP2), 168 to 182 (SP3), and 189 to 211 (SP4) of the HDAg molecule were synthesized and probed by enzyme-linked immunosorbent assay with a panel of 80 serum specimens from 45 patients suffering from either HDV-hepatitis B virus coinfections (n = 17) or HDV superinfections (n = 28). Sera from infected patients recognized these relatively short peptides. Peptide SP2 was the most antigenic; 71% of serum specimens reacted. Antibody to SP2 was also the commonest in sera taken early in the course of the disease. Peptide SP2 corresponds to one of the two regions which is highly conserved between different isolates. Among the 63 serum specimens which scored anti-HD positive by a commercial assay, all but 3 reacted to at least one of the peptides (95% agreement). Peptide assays appeared to be significantly more sensitive than the commercial assay with native HDAg early in the course of HDV infection since 14 of 17 (82%) serum specimens which scored anti-HD negative in the commercial assay reacted to one or more peptides. All serum specimens giving one or more positive results with the various peptides were confirmed as being HDV positive by an inhibition assay with free peptide in solution. The immune response to HDAg peptides vared greatly between individuals. No specific reactivity profile could be assigned to those with either HDV-hepatitis B virus coinfections or HDV superinfections. Overall, HDAg peptides appeared to be convenient reagents in addition to native antigen for the development of new and improved diagnostic tests for HDV infection.

Prevalence and persistence of antibody titers to recombinant HIV-1 core and matrix proteins in HIV-1 infection

Numerous studies have established the correlation between antibodies to the core protein p24 of HIV-1 and the progression of the acquired immunodeficiency syndrome. In this study, we analyzed the immune response to two recombinant gag proteins, p24 and p17, in order to evaluate their diagnostic or prognostic significance. Immune response to the immunodominant domain of the transmembrane glycoprotein gp41 was used as a reference. Sera collected from individuals from France and Burundi (Central Africa) at various CDC stages of HIV-1 infection were tested using three sandwich enzyme-linked immunoassays developed with a synthetic peptide corresponding to the immunodominant domain of gp41, SP gp41, or recombinant p24 and p17 cloned and expressed in Escherichia coli. These assays allowed detection of titer antibodies to the three cited antigens. Antibodies to SP gp41 were detected in every HIV-1-positive patient from France and Burundi, generally at a high and stable level. Results obtained with p24 confirmed the value of antibodies to p24 as a prognostic marker only in European and North American populations, since the African population had very high levels of these antibodies even at an advanced stage of the disease. They also confirmed that initial antibody response to p24 is more predictive of outcome than antibody titer change over time. Although antibodies to p17 decline during progression to AIDS, they are frequently absent in French patients at early, asymptomatic stages and therefore could not be used as a prognostic marker. In contrast, antibodies to p17 are significantly less common in African patients with AIDS when compared with symptomless HIV-1-infected African individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

Discrimination between human T-cell lymphotropic virus type I and II (HTLV-I and HTLV-II) infections by using synthetic peptides representing an immunodominant region of the core protein (p19) of HTLV-I and HTLV-II

We describe enzyme immunoassays that use synthetic oligopeptides to discriminate serologically between human T-cell lymphotropic virus type I and II (HTLV-I and HTLV-II) infections. The peptides represented 20-amino acid segments between residues 111 and 130 (MA1) and residues 116 and 135 (MA2) of the p19 gag proteins of HTLV-I and HTLV-II, respectively. The assays were sensitive since 69 of 74 HTLV-positive sera were reactive to at least one of the two matrix (MA) peptides (sensitivity, 93.2%). By using the ratio of the optical density of MA1 to the optical density of MA2, which represents for every serum sample the ratio between the absorbance value obtained in the MA1 assay and the absorbance value obtained in the MA2 assay, 59 of the 69 reactive serum samples were clearly and easily typed as positive for either antibody to HTLV-I or antibody to HTLV-II. Eight of the 10 remaining reactive serum samples were analyzed further by an inhibition procedure, and their type specificities were then clearly identifiable. Therefore, the results indicate that all MA-reactive sera were serologically distinguished by our peptide assays.

Lipid synthesis and apolipoprotein gene expression in hepatocytes in primary culture from (puromycin-induced) nephrotic rats

Primary culture of hepatocytes from puromycin aminonucleoside-induced nephrotic rats were used to discriminate between the hepatic and extra-hepatic contribution to the hyperlipidemia occurring in the nephrotic syndrome. De novo lipogenesis and utilization of exogenous fatty acids were not modified in nephrotic hepatocytes as compared to controls. In contrast 2.2 and 5.3-fold more triacylglycerol and phospholipids were secreted respectively by nephrotic hepatocytes than by controls. Triacylglycerol overproduction was not associated with an increase either in apo B mRNA level or in apo B synthesis or secretion measured by [35S]-methionine incorporation and immunoprecipitation. We also observed a significant increase in apo AI and apo E synthesis and secretion by nephrotic hepatocytes. This increase was correlated with a greater amount of apo AI and apo E mRNA than in controls. The overproduction of apo AI and apo E by nephrotic hepatocytes might intervene in the clearance of plasma lipoproteins and the redistribution of plasma cholesterol.

Effect of simvastatin on the synthesis and secretion of lipoproteins in relation to the metabolism of cholesterol in cultured hepatocytes

In primary culture of rat hepatocytes, simvastatin, a powerful HMGCoA reductase inhibitor, inhibited acetate incorporation into cellular and secreted cholesterol and cholesteryl-esters, without any significant effect on triacylglycerol synthesis and secretion. When applied to the culture for 24 h at 10(-7) M, a concentration shown to inhibit cholesterol synthesis by 61%, simvastatin increased apolipoprotein BH and BL synthesis and secretion and strongly decreased apolipoprotein AI synthesis and secretion whereas apolipoprotein AIV remained unaffected. The synthesis and secretion of apolipoprotein E was only slightly affected in contrast with other situations where cholesterol synthesis decreased. All of these modifications occurred at a post-transcriptional level, as the corresponding messenger RNAs of the apolipoproteins did not vary. These results suggest that either the drug itself or variations in cholesterol synthesis might be involved in apo B and apo AI synthesis and secretion.

Site-directed serology using synthetic oligopeptides representing the C-terminus of the external glycoproteins of HIV-1, HIV-2, or SIVmac may distinguish subtypes among primate lentiviruses

In this study the presence of a highly immunogenic domain located at the C-terminus of the external glycoproteins (EGP) of human and simian immunodeficiency viruses (HIV-1, HIV-2, and SIVMAC) is shown using synthetic oligopeptides as antigens in enzyme immunoassays. This epitope is probably located within the last 13 and 15 residues of the EGP of HIV-1 and HIV-2, respectively. The C terminal epitope of the EGP of SIVMAC may involve residues located more upstream. Among the HIV-2/SIV serotype, we observed that the reactivity to the C-terminal epitope of gp120 was dependent of both species and geographical origin of the samples tested. It seems that this gp 120 C-terminal epitope could distinguish subtypes among the HIV-2/SIV serotype. Further studies, using site-directed enzyme immunoassays with synthetic peptides representing the C-terminus of the EGP derived from a wide variety of HIV2/SIV strains must be performed to confirm this observation. These kinds of assays may constitute important tools for use in seroepidemiological studies and broaden our understanding of the distribution and phylogenetic relationship of primate lentiviruses.

Fine serotyping of human immunodeficiency virus serotype 1 (HIV-1) and HIV-2 infections by using synthetic oligopeptides representing an immunodominant domain of HIV-1 and HIV-2/simian immunodeficiency virus

In this study, enzyme immunoassays for detection of type-specific antibodies to human immunodeficiency viruses (HIV) were developed by using short peptides corresponding to sequences located within the immunodominant domain of the transmembrane glycoproteins of both HIV-1 and HIV-2-simian immunodeficiency virus (SIV). The assays were highly sensitive with currently available sera from various geographical areas. Furthermore, they appeared to be more specific in HIV serotyping than the Western blot (immunoblot) assay, since all of the sera were clearly discriminated as one or the other type. It was also shown that in contrast to HIV-1, the C-terminal cysteine residue (amino acid 620, SIV from captive macaques, Mm142 strain) of the HIV-2-SIV peptide is not necessary for recognition of the peptide by antibody to HIV-2.

Immune response to a major epitope of p24 during infection with human immunodeficiency virus type 1 and implications for diagnosis and prognosis

A sequential inhibition enzyme-linked immunoassay (SIEIA) using a peroxidase-conjugated monoclonal antibody reacting to the sequence AAEWDRVHP of p24HIV-1 (amino acids 209 to 217 of p55) was developed in order to detect and determine the titer of antibody to this epitope in various populations of human immunodeficiency virus type 1 (HIV-1)-positive patients. There was a good correlation between SIEIA and a commercially available competition assay that uses recombinant p24 protein and polyclonal antibody to HIV-1 antigen, demonstrating the importance of the described epitope. Analysis of sera from French patients showed a decline of antibody to the AAEWDRVHP sequence associated with the progression of AIDS. No decrease was observed with serum samples from African patients. An immune response to the epitope was detected by SIEIA early in the course of seroconversion. Although our SIEIA uses a single p24 epitope, these data are in accordance with previously published studies in which antibodies to the whole p24 were analyzed. Sera reacting to p24 only (indeterminate profiles by Western blot [immunoblot]) did not bind to AAEWDRVHP. This epitope, which is conserved between HIV-1 and HIV-2/simian immunodeficiency virus, appears to be a major antigenic domain of p24. The area containing the sequence AAEWDRVHP and the corresponding monoclonal antibody may serve as a convenient alternative to whole purified p24 and polyclonal antibody in diagnostic and prognostic assays.

Linear B-cell epitopes of the major core protein of human immunodeficiency virus types 1 and 2

Nine murine monoclonal antibodies directed to the major core protein p24 of human immunodeficiency virus type 1 (HIV-1) were obtained and then tested by using an epitope mapping system (Pepscan) covering the whole p24HIV1 protein to characterize antigenic domains. Four different linear epitopes were identified. Monoclonal antibodies recognizing three of these epitopes also reacted to p26HIV2 in Western blotting (immunoblotting). A monoclonal antibody specific for the fourth epitope, located at position 179 to 188 of the gag polyprotein p55HIV1 (human T-cell lymphotropic virus type 3B strain), did not react with HIV type 2 (HIV-2) core proteins. The corresponding sequence is constant in all known HIV-2 and simian immunodeficiency virus (SIV) isolates, including a very divergent SIV strain from African green monkeys (SIVagm/tyo). This observation may be relevant to the phylogeny of primate lentiviruses. Two of the conserved epitopes might be immunogenic during natural infection and could therefore be used for diagnosis and prognosis purposes. These two epitopes are AAEWDRVHP and EIYKRWII, starting at positions 209 and 260 of the polyprotein p55HIV1, respectively.

Fatty acid composition of rat liver mitochondrial phospholipids during ethanol inhalation

Male Sprague-Dawley rats were exposed to increasing concentrations (15-22 mg/l) of ethanol vapor over a 4-day period. Phospholipids were analyzed in liver mitochondria isolated from ethanol-treated and pair-weighted control animals. After a 2-day inhalation period, the proportion of monoenoic acids in total phospholipids increased, whereas that of arachidonic acid decreased. These changes were more striking in phosphatidylcholine (PC) than in phosphatidylethanolamine (PE). The decrease in 20:4 may be related to increased lipid peroxidation. After a 4-day inhalation period, quite different changes in phospholipid fatty acids were found. They consisted in a trend towards a more unsaturated system, the proportion of 20:4 being increased in PC and that of 22:6 in PE. This increase in polyunsaturated acids might be related to a direct ethanol effect on lipid structure and/or metabolism that would be linked to the high blood alcohol level present at this stage of ethanol intoxication.

Hepatic lipid peroxidation and mitochondrial susceptibility to peroxidative attacks during ethanol inhalation and withdrawal

Male Sprague-Dawley rats were exposed to increasing concentrations (15-22 mg/l) of ethanol vapor over a 4-day period. The hepatic lipid peroxide level as well as the sensitivity of mitochondria and microsomes to peroxidative attacks were studied during the early stage of alcohol intoxication, at the end of the inhalation period and, finally, during withdrawal. The level of hepatic lipid peroxide started to increase significantly after the first day of ethanol inhalation, whereas the in vitro mitochondrial sensitivity to peroxidation induced by ADP X Fe3+ in the presence of an O(2)-generating system was still unaltered after a 2-day inhalation period. Both the hepatic peroxide level and the mitochondrial sensitivity to peroxidation were significantly enhanced at the end of the 4-day inhalation period. Such an enhancement was still apparent 24 h after withdrawal, a time at which no more ethanol was present in the blood. Lipid peroxidation returned to normal values only 48 h after withdrawal. Microsomes were less affected than mitochondria by the ethanol treatment. It is suggested that the alterations of lipid peroxidation are related to the presence and/or the metabolism of ethanol at an early stage of inhalation, whereas changes in the membrane structure would be responsible for the maintenance of enhanced lipid peroxidation 24 h after ethanol withdrawal.

Inhibition of free fatty acid release from isolated rat epididymal fat cells by some natural occurring organic acids

The effects of some mono-, di- and tricarboxylic substrates (acetate, pyruvate, L-lactate, L-alanine, D,L-beta-hydroxybutyrate, succinate, D,L-malate, alpha-oxoglutarate, L-glutamate and citrate) on the basal lypolytic activity of isolated white adipocytes from fasted rats were investigated "in vitro". At concentrations ranging from 1 to 10 mM, the compounds tested, except lactate, had no influence on the rate of glycerol release but markedly reduced the free fatty acid (FFA) release. Lactate reduced both the glycerol and FFA release. As this "in vitro" lowering effect on FFA release was observed using concentrations occurring "in vivo" in the blood for lactate, beta-hydrobutyrate, and alanine, these results suggest that, besides lactate and beta-hydroxybutyrate, alanine may also assume an important role in the "in vivo" regulation of peripheral FFA mobilization and consequently of ketogenesis.