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Biomedical subjects

D Samuel

Publications and source records attributed to D Samuel.

At least 199 records · Page 11Linked to original sources
PubMed1990

Serum hepatitis delta virus RNA in patients with delta hepatitis and in liver graft recipients.

We have investigated the usefulness of serum hepatitis delta virus (HDV) RNA detection using a slot hybridization analysis of serum samples from ten patients with acute hepatitis and delta markers (group I), from 28 patients with chronic delta hepatitis (group II) and from seven liver graft recipients with hepatitis B virus (HBV) and HDV related cirrhosis or fulminant hepatitis (group III). The slot-blots were hybridized with both HDV-complementary DNA and single-stranded RNA probes. With the single-stranded RNA probe, HDV RNA was detected in the first serum sample available in 9/10 of the patients with acute hepatitis (group I). In addition, HDV RNA was detected in 8/9 and 7/8 of the samples obtained within and after 1 month of the onset of hepatitis. Five of the ten patients scored positive for HDV RNA and negative for hepatitis delta antigen (HDAg) while one was negative for HDV RNA and positive for HDAg. The same RNA probe enabled the detection of serum HDV RNA in 21/28 chronic hepatitis patients (liver HDAg and/or IgM anti-HD positive) (group II). Among the liver graft recipients (group III), 7/7 had a recurrent delta infection. Serum HDAg, liver HDAg and anti-HD IgM were identified in 3/7, 6/7 and 5/7 of the patients, respectively. HDV RNA was detected in the seven patients with either persistent (4/7) or transient (3/7) positivity. In addition, HBsAg and HBV RNA were persistently shown in 4/7 patients with continuous HDV replication. In the remaining three patients, HDV RNA was detectable despite the absence of HBsAg.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Comparison of the activity of three antibiotic regimens in severe Legionnaires' disease.

Comparison of the activity of different antibiotic regimens in Legionnaire's disease has never been made because of the rarity of well documented cases of that disease. We have retrospectively compared severe cases of Legionnaires' disease treated with pefloxacin alone or in combination with erythromycin and/or rifampicin using computer-matched cases treated either with erythromycin or with erythromycin in combination with rifampicin. This study suggests that: (1) combined therapy including erythromycin, rifampicin and/or pefloxacin is superior to therapy with erythromycin alone; (2) combinations including pefloxacin may be the most active ones; and (3) pefloxacin alone may be as active as combination therapy. Although these results are in agreement with data obtained in cell and in animal models of legionella infection they need to be further confirmed by the study of larger number of patients.

Cause of Death↗
PubMed1990

Persistent hepatitis B virus infection of mononuclear blood cells without concomitant liver infection. The liver transplantation model.

We have investigated the recurrence of Hepatitis B virus (HBV) in 30 patients treated by orthotopic liver transplantation and given high doses of anti-HBs immunoglobulin. The polymerase chain reaction (PCR) assay showed no evidence of HBV DNA sequences in the liver of 23/24 patients who remained serum HBsAg-negative during a mean follow-up of 13 months (2-24 months) after OLT. However, the liver scored positive in all the 6 individuals in whom HBsAG reappeared. The PCR assay identified HBV DNA sequences in the peripheral blood mononuclear cells of 7 of 11 subjects who were serum HBsAG-negative and liver HBV DNA-negative by PCR. Therefore, this application of the sensitive PCR assay demonstrates persistent infection of PBMC in the absence of liver HBV--thus OLT provides a model for studying the interaction between HBV, PBMC, and the liver.

DNA, Viral↗
PubMed1990

Detection of diphtheria toxin in culture supernates of Corynebacterium diphtheriae and C. ulcerans by immunoassay with monoclonal antibody.

Monoclonal antibody (MAb) to diphtheria toxin was produced in mouse hybridomas, and shown by ELISA to be of sub-class IgG1. Hybridomas were inoculated into mice to produce ascitic fluid from which MAb was purified by caprylic acid. The MAb was shown by immunoblotting to be directed against the A fragment of the toxin and also against the intact toxin molecule. After conjugation with fluorescein isothiocyanate, it was used in an immunoassay to detect toxin in culture supernates of Corynebacterium diphtheriae and C. ulcerans. The assay correlated well with the Elek test and with virulence in guinea-pigs; but it gave occasional false positive results, probably by binding of MAb to defective toxin.

Animals↗
PubMed1990

Localization of N-methyl-D-aspartate receptors in the rat striatum: effects of specific lesions on the [3H]3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid binding.

The binding of [3H]3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid ([3H]CPP), a rigid analogue of 2-amino-7-phosphonoheptanoic acid (AP7) and reported to be a selective N-methyl-D-aspartate (NMDA) antagonist, was studied in rat striatal membranes using a centrifugation procedure to separate bound and free radioligand. [3H]CPP bound with high affinity (KD = 272 nM) in a saturable, reversible, and protein concentration-dependent manner. Specific binding was suggested to involve a single class of noninteracting binding sites. The most potent [3H]CPP binding inhibitors tested were CPP, L-glutamate, 2-amino-5-phosphonovalerate, and AP7. NMDA, L-aspartate, and alpha-aminoadipate were also shown to be efficient in inhibiting the binding, whereas quisqualate, D,L-2-amino-4-phosphonobutyrate, kainate, L-glutamate diethylester, and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid were found to be essentially inactive. These data are therefore consistent with the view that [3H]CPP selectively binds to NMDA receptors in the rat striatum. Lesions of intrastriatal neurons using local injections of kainic acid revealed a marked decrease in [3H]CPP binding, suggesting an almost exclusively postsynaptic location of binding sites in the striatum. Conversely, bilateral lesion of corticostriatal glutamatergic fibers resulted in an increased number of [3H]CPP striatal binding sites, providing evidence for a putative supersensitivity response to this striatal deafferentation. Interestingly, lesion of the nigrostriatal dopaminergic neurons using intranigral 6-hydroxydopamine injections resulted, 2-3 weeks later, in a similar increase in the number of [3H]CPP striatal binding sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1990

Evaluation of urinary antigen ELISA for diagnosing Legionella pneumophila serogroup 1 infection.

The enzyme linked immunosorbent assay (ELISA) described was developed to detect a soluble antigen in the urine of patients with Legionnaires' disease caused by Legionella pneumophila serogroup 1 (L.pn 1). The assay was evaluated and showed good specificity (100%) and intra-assay reproducibility. Antigen was detected in the urine of 93 (77%) of 120 patients, overall, and in 86% of patients from whom a specimen obtained within seven days of onset of illness was available. On all but one occasion the first urine sample taken from a patient for whom a positive ELISA result was obtained, was itself positive. In one case antigen was not detected at four days but was present on the fifth day after onset of symptoms. In two patients urinary antigen was detectable as early as two days after onset of symptoms. In another the antigen persisted for at least 60 days. More than half the patients, however, had stopped producing detectable antigen within 14 days of onset of symptoms. It is therefore important that where Legionnaires' disease is suspected urine is collected as early as possible in the course of the disease.

Antigens, Bacterial↗
PubMed1990

The use of enzyme immunoassay (EIA) and radiobinding assay to investigate the cross-reactivity of Klebsiella antigens and HLA B27 in ankylosing spondylitis patients and healthy controls.

The binding of rabbit anti-Klebsiella antibodies to tissue-typed lymphocytes obtained from 30 ankylosing spondylitis (AS) patients and 54 healthy subjects has been measured by an enzyme immunoassay method. HLA B27 positive lymphocytes obtained from either AS patients (t = 3.60; p less than 0.001) or healthy subjects (t = 3.77; p less than 0.001) were found to bind Klebsiella antibodies to a significantly greater extent than non-B27 lymphocytes obtained from healthy controls. Absorption studies demonstrated that HLA B27 positive lymphocytes absorbed out significantly more anti-Klebsiella antibodies than HLA B27-negative lymphocytes (t = 6.76; p less than 0.005). These results are compatible with cross-reactivity or molecular mimicry between HLA B27 and epitopes on some Gram-negative bacteria such as Klebsiella.

Antigens, Bacterial↗
PubMed1990

[Rapid diagnosis of cytomegalovirus hepatitis after liver transplantation. Use of monoclonal antibody E13 directed against an early viral antigen].

Liver biopsies obtained from 10 liver transplant patients for whom a cytomegalovirus (CMV) hepatitis was suspected on the basis of clinical and biological abnormalities have been studied by an immunohistological method using the monoclonal antibody E-13 directed against an early viral antigen. Biopsies were performed between the 30th and the 77th day after transplantation. In 7 of the 10 cases, CMV hepatitis was diagnosed by histological examination because of the association of lobular cytolysis, inflammatory infiltrate with neutrophils and intranuclear inclusions. Ten cases were positive with the E-13 antibody including the 3 cases in which histological examination was not conclusive. In all cases, positive results gave a nuclear staining pattern in hepatocytes (63%) or endothelial cells (40%), independently of the presence of inclusions. Rapid diagnosis of CMV hepatitis is of significant importance since anti-viral drugs, such as DHPG (Ganciclovir), are now efficient. The immunohistochemical method with E-13 could permit easy and rapid detection of CMV in liver specimens.

Adolescent↗
PubMed1989

The FITC-anti-FITC system is a sensitive alternative to biotin-streptavidin in ELISA.

In a model ELISA system alkaline phosphatase (AP) absorbed onto microtitre wells was employed as the target antigen. The antigen was then reacted with a monoclonal antibody to AP either unlabelled or labelled with (a) FITC and (b) biotin. The bound anti-AP was then detected with horseradish peroxidase (HRP) conjugates of polyvalent anti-mouse IgG, and the FITC and biotin anti-AP conjugates with HRP conjugates of a monoclonal anti-FITC or streptavidin respectively. The FITC-anti-FITC system proved to be of similar sensitivity to the biotin-streptavidin system detecting 140 amol compared to 350 amol of antigen. Both these methods of antigen detection were superior to the anti-mouse IgG reagent (2100 amol). In contrast to biotinylated antibodies, FITC-labelled antibodies are highly coloured and fluorescent. These features aid the preparation, purification and characterisation of conjugates. In addition, very low non-specific binding is encountered with enzyme conjugates of anti-FITC and this may confer an advantage over enzyme conjugates of avidin/streptavidin reagents.

Alkaline Phosphatase↗