T cell allorecognition and endogenous HLA-B27-bound peptides in a cell line with defective HLA-B27-restricted antigen presentation

The B*2702+ lymphoblastoid cell line NW is unable to present at least some HLA-B27-restricted viral antigens to T cells. This defect was genetically inherited, and was suggested to be related to the nature of the HLA-B27 binding peptides reaching the endoplasmic reticulum in these cells (Pazmany et al., J. Exp. Med. 1992. 175: 361). In the present study 17 of 19 HLA-B27-specific alloreactive cytotoxic T lymphocyte clones recognizing the B*2702 subtype on other cells also lysed NW cells. Only two cytotoxic T lymphocyte clones failed to lyse NW while efficiently killing other B*2702+ cell lines. The high-performance liquid chromatography profiles of the B*2702+ bound peptides extracted from NW cells was similar, but not identical, to those from two other cell lines. These results indicate that the HLA-B27-bound peptide repertoire in NW cells is not fundamentally different from those in other B*2702+ cells. Our data argue against gross differences in peptide processing or transport as being responsible for the defective presentation of particular HLA-B27-restricted viral antigens to T cells, but do not rule out distinct presentation of some endogenous peptides. Differences in the capacity to present certain peptides could cause differential susceptibility among HLA-B27+ individuals to ankylosing spondylitis.

Histological study in contralateral testis of prepubertal children following unilateral testicular torsion

Histological changes in the contralateral testis in 8 prepubertal children whose ages ranged from 3 to 7.5 years with a history of testicular torsion and subsequent atrophy were studied. The following histological parameters were evaluated: fertility tubular index (FTI), Sertoli cell index (SCI) and minimum tubular diameter (MTD). According to our findings and following Nistal and Paniagua's classification (1984) for tubular alterations, we found 5 cases (62.5%) who present the following alterations. Type 1 (case 2): FTI was decreased above 50% corresponding to slight germinal hypoplasia with normal MTD and SCI. Type 2 (cases 3 and 5): testis with remarkable germinal hypoplasia; FTI was between 30 and 50% while MTD was below normal values. Type 3 (case 8): testis with diffuse tubular hypoplasia; FTI was below 30%, whereas MTD showed 33% decrease regarding normal values. Type 4 (case 6): testes with hyperplasia of Sertoli cells; SCI was increased one third with regard to that corresponding to his age; FTI showed severe hypoplasia of germ cells. No relationship between alterations in either the age of the patients or the time elapsed since the torsion was observed. Because of all these facts and the young age of our patients, we believe that the alterations found in the contralateral testis were due to congenital dysgenesia.

Serum hepatitis B virus DNA detection with S- and C-region-directed probes

Developments in molecular biology have offered a wide range of nucleic acid probes to detect the genome of hepatitis B virus (HBV). We have tested the ability of two enzyme-linked (alkaline phosphatase) probes to detect HBV-DNA. These hybridise with the S and C regions of the genome of HBV and are used to determine the clinical significance of detecting the two regions. A total of 66 serum samples from patients at different stages of HBV infection was examined. HBV-DNA was detected with at least one of the probes in 17 (85%) patients with HBeAg-positive chronic hepatitis, five (26.3%) with anti-HBe-positive chronic hepatitis and six (66.6%) with acute hepatitis. Although both probes were able to detect as little as 10 pg/ml (2.86 x 10(6) g.E./ml) of a full length HBV-DNA standard, the C-region-directed probe did not react in one patient with acute hepatitis, two with HBeAg-positive and three with anti-HBe-positive chronic hepatitis. When C-region-directed probes are used for diagnostic purposes, results should always be accompanied by hybridisation with probes directed against other regions showing less variability (e.g. S region).

[Prevalence of non-insulin dependent diabetes mellitus in Lejona (Vizcaya, Spain)]

BACKGROUND

Diabetes mellitus presents a high prevalence and morbimortality. The aim of the present study was to know the number of newly diagnosed diabetic patients in addition to those who present abnormal glucose tolerance and possible presence of associated risk factors.

METHODS

This study was carried out in Lejona (Vizcaya) from 1984-1985. The prevalence of non insulin-dependent diabetes mellitus (NIDDM) and abnormal glucose tolerance (AGT) in people older than or equal to 30 years of age by a randomized sample stratified by pyramids of age and sex (n = 862). The following data were collected: age, sex, height, weight, medications taken, family and personal history of diabetes mellitus (DM) and blood pressure. A glycemia curve was made following the criteria recommended by the Committee of Experts of the World Health Organization (WHO).

RESULTS

The prevalence of DM observed in the sample was of 6.4% (confidence interval of 95%: 4.75-8.01%) of which 3.6% corresponded to unknown DM and 2.8% to known DM. The prevalence of AGT was 10.4% (confidence interval 95%: 8.40-12.48%). Greater association was observed between DM and obesity, lower height, high blood pressure and age over 50.

CONCLUSIONS

More than half of the diabetics were unaware of the disease. Given the association of non insulin-dependent diabetes mellitus with modifiable factors (obesity, high blood pressure) control of risk factors would be useful with the aim of decreasing the prevalence of diabetes mellitus and avoid the associated chronic complications of the disease.

Melanin production by Rhizobium meliloti GR4 is linked to nonsymbiotic plasmid pRmeGR4b: cloning, sequencing, and expression of the tyrosinase gene mepA

Melanin production by Rhizobium meliloti GR4 is linked to nonsymbiotic plasmid pRmeGR4b (140 MDa). Transfer of this plasmid to GR4-cured derivatives or to Agrobacterium tumefaciens enables these bacteria to produce melanin. Sequence analysis of a 3.5-kb PstI fragment of plasmid pRmeGR4b has revealed the presence of a open reading frame 1,481-bp that codes for a protein whose sequence shows strong homology to two conserved regions involved in copper binding in tyrosinases and hemocyanins. In vitro-coupled transcription-translation experiments showed that this open reading frame codes for a 55-kDa polypeptide. Melanin production in GR4 is not under the control of the RpoN-NifA regulatory system, unlike that in R. leguminosarum bv. phaseoli 8002. The GR4 tyrosinase gene could be expressed in Escherichia coli under the control of the lacZ promoter. For avoiding confusion with mel genes (for melibiose), a change of the name of the previously reported mel genes of R. leguminosarum bv. phaseoli and other organisms to mep genes (for melanin production) is proposed.

Effects of different factors in lead- and cadmium-induced hypothermia in mice

The aim of this study was to investigate the relationship between the hypothermic effect induced by lead or cadmium chloride treatments and the cerebral metal levels attained. Mice were injected intraperitoneally with different doses of lead acetate or cadmium chloride at ambient temperatures of 22 degrees C and 35 degrees C, and rectal temperatures and brain metal levels were determined. At 22 degrees C, doses of lead acetate exceeding 25 mg/kg caused significant hypothermia and a rise of lead levels in the brain; this hypothermic effect was significantly inhibited at 35 degrees C. In mice repeatedly treated with 2 or 5 mg/kg lead acetate and exposed to 22 degrees C or 35 degrees C, no significant changes were observed in body temperature after the repeated exposure, although brain lead levels increased significantly. Cadmium chloride at 22 degrees C produced a significant fall in body temperature, and a rise in brain cadmium levels at doses of 2-4 mg/kg; the decrease in body temperature was partially inhibited at 35 degrees C. The results of the present study suggest that the hypothermic effect elicited by these heavy metals is related to both the level of metal absorbed by the brain and its rate of uptake.

Kinetics of hypodermically injected technetium-99m and correlation with cutaneous structures: an experimental study in dogs

We investigated the involvement of cutaneous structures in specific linear migration pathways of technetium-99m pertechnetate hypodermically injected at points of low electrical resistance in the metacarpus of male beagles. Skin-deep incisions were made in the front or back legs on either the same side as the 99mTc injection or on the opposite side. Incisions in the back legs did not affect the migration pattern. Incisions in the front legs before the injection of 99mTc prevented tracer migration. After the injection of 99mTc, incisions in the front contralateral leg caused sudden cessation of the migration, while incisions in the ipsilateral leg caused immediate disappearance of the pathway previously observed. Radioactivity was not detected in flaps obtained from the skin overlying the migration pathway or from the corresponding area of the contralateral leg. In conclusion, the specific linear migration pathways of 99mTc hypodermically injected at points of low electrical resistance cannot be explained by any known biological function. Although the migration of 99mTc does not seem to be strongly linked to any cutaneous structure, the skin overlying the radioactive pathway and the corresponding area of the contralateral leg must be intact if tracer migration is to take place.

Diagnosis of HIV-1 infection by PCR with two primer pairs

We have used two different primer pairs to assess HIV-1 infection of peripheral blood mononuclear cells (PBMC) by polymerase chain reaction (PCR). The study was carried out on 150 individuals: 50 seronegative individuals without risk behaviours for HIV-1 infection, 50 individuals with risk-behaviours but seronegative for HIV-1 and 50 patients with risk-behaviours who were HIV-1 seropositive. Discordances were found between the two primer pairs (SK38/39; SK68/69) in 3 cases. In the non-risk seronegative group, one specimen was scored positive with only one primer pair (SK38/SK39); all the samples belonging to seropositive individuals were found to be positive for HIV-1 DNA using both primer pairs; in the seronegative at risk group 2 samples were positive with only one primer pair (SK38/SK39), and 4 samples were found positive by both primer pairs (SK38/39 & SK68/69). Our study demonstrates that discrepant results take place with relatively high frequency; we propose that all specimens should be tested twice using at least two different primer pairs.

[Conjunctival ophthalmomyiasis caused by Oestrus ovis]

BACKGROUND

Microbiologic diagnosis of conjunctival ophthalmomyiasis.

MATERIAL AND METHODS

Material extracted from three patients' conjunctiva who complained of sudden presence of foreign body and were diagnosed as conjunctival ophthalmomyiasis has been studied. Patients were recruited over two months from the Emergency Department. Diagnosis was performed through observation using the light microscope.

RESULTS

Oestrus ovis first-instance larvas were observed in all the samples studied.

CONCLUSIONS

This observation of similar cases in a short period of time and the low frequency of diseased people who lived in a urban environment makes necessary to think in this agent as cause of ophthalmomyiasis in our area and therefore perform an adequate differential diagnosis.

[Evaluation of DNA-HIV detection in various population groups]

BACKGROUND

To evaluate the diagnostic use of Polymerase Chain Reaction (PCR) for the detection of HIV-DNA.

METHODS

We have investigated HIV-DNA in peripheral blood mononuclear cells of 150 individuals: 50 seronegative without recognized factors to acquire HIV infection, 50 seronegative that showed risk habits and 50 seropositive. For amplification we have used primers SK38/SK39 which amplify a conserved region of 114 bp from HIV's gag gen. The detection of the amplificate was performed using solution hybridization with 32P-labelled SK 19, 6% polyacrylamide gel electrophoresis and autoradiography.

RESULTS

We have detected HIV-DNA at every seropositive patient (100%), 6 samples from seronegative individuals that showed risk habits and 1 sample from non-risk seronegative individuals.

CONCLUSIONS

Polymerase chain reaction represents a diagnostic tool at HIV infection, specially for those patients where seroconversion can not be demonstrated by conventional methods.

Formation and characterization of cyclosporine-loaded nanoparticles

The commercially available formulations of cyclosporine (cyclosporin A, CyA) are associated with acute hemodynamic changes that result in high nephrotoxicity. Among colloidal vectors, nanoparticles (NPs) are receiving much attention as potential drug carriers that would avoid the therapeutic risks of conventional formulations. Two different mechanisms for obtaining polymeric NPs loaded with CyA were studied with regard to their preparation and physicochemical characterization. Isobutyl-2-cyanoacrylate monomer (IBCA) was polymerized, whereas poly-E-caprolactone (PCL, a preformed polymer) was precipitated; both reactions took place in an aqueous medium containing Pluronic F-68 (polyoxypropylene polyoxyethylene block copolymer) as a surface active agent. The encapsulation efficiencies were 78.49 +/- 5.87 and 84.85 +/- 5.02%, respectively, and they remained stable over a wide range of drug concentrations. The polymeric NP had average sizes of 81 +/- 25 and 95 +/- 25 nm for poly-IBCA and PCL, respectively, as confirmed by photon correlation spectroscopy. Poly-IBCA NPs were built from oligomers with molecular weights of 157 to 2644 that joined to form a polymeric nanomatrix. In vitro activity of the drug and the carrier was tested by inhibition of lymphocyte proliferation induced by Concanavalin A. Drug-loaded PCL NPs and free CyA inhibited lymphocyte proliferation by 91.40 and 86.19%, respectively. However, drug-free NPs also exhibited statistically significant (p < 0.05) immunosuppressive activity.

[A pathological study of valvular dysplasia and attachment in Ebstein's anomaly]

Forty hearts with Ebstein's disease of the tricuspid valve were studied in order to correlate dysplasia and attachment of tricuspid valve leaflets at the ventricular walls, atrialization of the right ventricle and fibrosis in this chamber. The correlation was positive. The right ventricular atrialization was directly proportional to leaflet attachment; the correlation in severity between leaflet attachment; the correlation in severity between leaflet attachment and dysplasia was positive in 45%. The right ventricular fibrosis was very frequent in the group with patent pulmonary valve (90%), and the contrary was in the group with pulmonary valve atresia (10%). The structural damage in the right ventricular wall was directly proportional to leaflet attachment in hearts with patent pulmonary valve (90%); in all of these hearts the anatomic annulus of the tricuspid valve was enlarged but in hearts with pulmonary valve atresia this feature only occurred in 10%. The specimens with atrioventricular discordant connexion, the anatomic annulus size, the degree of leaflet attachment, the dysplasia of the tricuspid valve as well as the fibrosis of the wall of the right ventricle were less severe compared with those hearts with concordant atrioventricular connexion. Ebstein's disease of the tricuspid valve is characterized by a disorder in the histodifferentiation of the right ventricle and the tricuspid valve which originates in great part from it.

Changes in the repertoire of peptides bound to HLA-B27 subtypes and to site-specific mutants inside and outside pocket B

HLA-B27 subtypes share many structural features, including their pocket B, which interacts with a conserved Arg residue at the second position of B*2705-bound peptides. Subtypes differ among each other at other locations in the peptide binding site. In this study, metabolic labeling and radiochemical pool sequencing were used to address the following issues: (a) presence of the Arg 2 (R2) motif among peptides bound to the various HLA-B27 subtypes; (b) influence of mutations inside and outside pocket B on this motif; and (c) the degree of similarity among the peptide pools bound to the various B27 subtypes. Sequencing of Arg-labeled peptide pools extracted from B*2701 to B*2706, and from two site-directed mutants of B*2705 with changes outside pocket B, indicated that all of these molecules bind peptides with Arg at position 2. Peptides from several mutants with changes altering the structure of pocket B, and from one mutant at the pocket B rim, also retained the R2 motif. However, this was absent in the peptide pool extracted from the M45 mutant, in which the negative charge of pocket B, conferred to HLA-B27 by Glu45, was canceled. These results indicate that alterations outside pocket B, and even disruption of the network of hydrogen bonds that stabilizes Arg binding in pocket B, do not impair binding of peptides bearing the R2 motif, but a nonconservative substitution at position 45 does. As a substantial fraction of anti-B*2705 cytotoxic T lymphocyte (CTL) clones crossreact with the M45 mutant (Villadangos, J., B. Galocha, D. López, V. Calvo, and J. A. López de Castro. 1992. J. Immunol. 149:505) this result suggest that determinant mimicry by nonidentical peptides may frequently account for unexpected CTL crossreactions. Metabolic labeling with various other amino acids and radiochemical sequencing revealed similarities, but also substantial differences, among the peptide pools from the various HLA-B27 subtypes. This strongly suggests that many peptides bind to multiple subtypes, but significant subsets of peptides bound to a given HLA-B27 subtype do not bind to other subtypes or do so with greatly altered efficiency. These results indicate the importance of polymorphism outside pocket B in modulating peptide binding to HLA-B27.

[Annual cost of microbial immunological tests for HIV-positive individuals in a hospital center]

The goal of this study is to increase the knowledge of the AIDS cost in a hospital. We have studied the HIV patients diagnosed during a year in our hospital and the charges of the serological tests performed to them. 20.8% of the tests were to study antibodies against HIV (only 20% were positive). After patient distribution between extra or intrahospital origin, we highlight that 61% of the charges are attributed to patients who do not belong to the hospital but to its catchment area. We emphasize the problem that AIDS patients are creating to hospital, being necessary that personal select only useful tests honestly.

Experimental study on radioactive pathways of hypodermically injected technetium-99m

The objective of this study was to investigate the biological substrate of radioactive pathways of migration of hypodermically injected 99mTc into points of low electrical resistance. Sixteen anesthetized adult male beagles were used. Control and test points were defined by comparing their electrical resistance to that of the pinna. Seventy-three experiments of three different types were performed: (1) separate hypodermic injections of [99mTc] sodium pertechnetate, 201Tl-chloride, 131INa and 99mTc-rhenium sulfide into control and test points; (2) simultaneous injections of [99mTc]sodium pertechnetate and 201Tl chloride into control and test points; and (3) intravascular injections of 99mTcO4 into blood vessels underlying test points. Only the hypodermic injection of 99mTc into points of low electrical resistance gave rise to a specific radioactive pathway characterized by rapid and longitudinal migration, clearly independent of background activity. The specific radioactive pathway detected is not the result of diffusion of the radiotracer through nerves, veins or lymphatic vessels, but its trajectory coincides with that described for one of the acupuncture meridians in the dog.

Influenza A viruses: epidemiologic study in fatteners in Spain (1987-89)

2,979 sera were collected from slaughtered swine in two geographic areas of Spain from 1987 to 1989. They were tested for antibodies against an H1N1- and H3N2-influenza virus by haemagglutination-inhibition tests (HI). The percentage of positive sera was higher in area I (78%-69.2%) than in area II (63.1%-60.4%) for both viruses respectively. The coexistence of high titres to both H1N1- and H3N2-influenza virus became apparent in cold months simultaneously in each area, although influenza viruses circulated in the Spanish swine population for two years. Also this study suggests the possible circulation of A/Texas/1/77-like strains in Spain, results which have not been reported before.

[Quantification of the levels of p24 antigen and antibodies in human immunodeficiency virus infection]

BACKGROUND

Quantification and clinical evaluation of p24 antigen and anti-HIV antibody levels.

METHODS

Follow up of 13 HIV infected patients (53 sera) by determination of p24 antigen, total anti-HIV antibodies, anti-p24 and anti-env antibodies by ELISA and their semiquantitation. IgG and IgM class antibody determination by immunoblot techniques.

RESULTS

The highest levels of p24 have been found in WR 1 and WR 6 stages. Commonly accepted serologic pattern has not been found in 100% of our cases. Western-blot is more sensitive for the detection of anti-p24 antibodies.

CONCLUSIONS

p24 antigen appearance and a decrease in anti-p24 antibody level is related to a worse clinical prognosis. p24 antigen quantification is a usefull test for monitoring AZT therapy in patients suffering from AIDS.