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Biomedical subjects

T Weber

Publications and source records attributed to T Weber.

At least 325 records · Page 18Linked to original sources
PubMed1989

CSF and serum beta-2-microglobulin in HIV infection related to neurological dysfunction.

Elevated (greater than 2.2 mg/l) CSF beta-2-microglobulin (beta 2m) level was found in 9 of 16 neurologically symptomatic patients but in only 4 of 21 who were neurologically symptom-free (P less than 0.01). Serum beta 2m concentration was elevated (greater than 2.5 mg/l) in 12 of 16 neurologically symptomatic patients but in only 8 of 21 symptom-free patients (P less than 0.01). When the CSF and serum beta 2m levels were related to various stages of HIV infection, the highest mean values for both CSF and serum were found in patients with acquired immunodeficiency syndrome (AIDS), followed by lower values in AIDS-related complex (ARC), lymphadenopathy syndrome (LAS), and asymptomatic seropositive individuals (ASX), in decreasing order of preference. Our results suggest that elevated beta 2m in CSF and serum is related to the stage of general HIV infection and that elevated CSF beta 2m in the presence of intact BBB may be useful in evaluating CNS involvement in HIV-infected patients.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Sex determination in the germ line of Drosophila depends on genetic signals and inductive somatic factors.

We have analyzed the mechanism of sex determination in the germ line of Drosophila by manipulating three parameters: (1) the ratio of X-chromosomes to sets of autosomes (X:A); (2) the state of activity of the gene Sex-lethal (Sxl), and (3) the sex of the gonadal soma. To this end, animals with a ratio of 2X:2A and 2X:3A were sexually transformed into pseudomales by mutations at the sex-determining genes Sxl (Sex-lethal), tra (transformer), tra-2 (transformer-2), or dsx (double-sex). Animals with the karyotype 2X;3A were also transformed into pseudofemales by the constitutive mutation SxlM1. The sexual phenotype of the gonads and of the germ cells was assessed by phase-contrast microscopy. Confirming the conclusions of Steinmann-Zwicky et al. (Cell 57, 157, 1989), we found that all three parameters affect sex determination in germ cells. In contrast to the soma in which sex determination is completely cell-autonomous, sex determination in the germ line has a non-autonomous component inasmuch as the sex of the soma can influence the sexual pathway of the germ cells. Somatic induction has a clear effect on 2X;2A germ cells that carry a Sxl+ allele. These cells, which form eggs in an ovary, can enter spermatogenesis in testes. Mutations that cause partial loss of function or gain of function of Sxl thwart somatic induction and, independently of the sex of the soma, dictate spermatogenesis or oogenesis, respectively. Somatic induction has a much weaker effect on 2X;3A germ cells. This ratio is essentially a male signal for germ cells which consistently enter spermatogenesis in testes, even when they carry SxlM1. In a female soma, however, SxlM1 enables the 2X;3A germ cells to form almost normal eggs. Our results show that sex determination in the germ line is more complex than in the soma. They provide further evidence that the state of Sxl, the key gene for sex determination and dosage compensation in the soma, also determines the sex of the germ cells, and that, in the germ line, the state of activity of Sxl is regulated not only by the X:A ratio, but also by somatic inductive stimuli.

Animals↗
PubMed1989

Rapid determination of C-reactive protein by enzyme immunoassay using two monoclonal antibodies.

Several monoclonal antibodies for human C-reactive protein (CRP) were characterized, and two antibodies binding to separate domains were used to construct a rapid and simple immunoenzymometric assay for CRP. The assay consists of a single 15 min immunological reaction during which CRP forms a complex with a peroxidase-labelled antibody and with another antibody attached to the test-tube wall. The immobilized complex is detected by a 3 min colour reaction using peroxidase substrate. The quantitative measuring range of the assay is 0.04-5 mg/l, and no hook occurs at five-fold higher values. The sensitivity of the method allows reliable determination of low CRP levels, eg. in paediatric samples. The values obtained with the present assay correlated well with turbidimetric results.

Adult↗
PubMed1989

Mapping of transcription units on Xenopus laevis lampbrush chromosomes by in situ hybridization with biotin-labeled cDNA probes.

A non-radioactive in situ hybridization method is described for the localization of transcription units of defined genes to lateral loops of Xenopus laevis lampbrush chromosomes. Two Xenopus cDNA probes were used encoding the nucleolar protein NO38/B23 and cytokeratin 1(8). Both proteins are known to be synthesized in Xenopus oocytes, and Northern blot analysis revealed the presence of the corresponding mRNAs in different oogenic stages. The probes were enzymatically labeled with biotin-dCTP and hybridized to lampbrush chromosomes. The sites of hybridization were detected either by indirect immunofluorescence microscopy using rabbit antibodies against biotin and fluorescein-conjugated anti-rabbit IgG or enzymatically using peroxidase-conjugated streptavidin. The probe encoding the nucleolar protein hybridized to two sets of lateral loops on different bivalents, the cytokeratin probe to at least four. Our finding that each probe hybridized to more than one chromosomal locus may reflect the tetraploid nature of the Xenopus laevis genome or results from cross-hybridization to other transcriptionally active members of the NO38/B23-nucleoplasmin or the cytokeratin-lamin gene families. The method described should facilitate further in situ hybridization studies with appropriate genomic clones in order to map specific DNA sequences to defined loop regions and to come to a better understanding of the relationship between loop organization and gene transcription unit.

Animals↗
PubMed1989

[Neuronotrophic interactions in the developing inner ear].

In the developing inner ear, the existence of a neuronal death and of a peripheral target-derived trophic effect on the embryonic cochleovestibular neurons is described. We investigate the molecular vector(s) of such neuronotrophic influences on the cochleovestibular neurons, particularly the nerve growth factor (NGF) which is a good candidate since receptors for this trophic factor are described in the embryonic inner ear. In 12 day-old rat embryos, we demonstrate the release of an NGF-like activity by the otic vesicle and the effect of this trophic factor on the survival and the neuritogenesis of the cochleovestibular neurons. We suggest an important role for NGF in the neuronal stabilisation of the cochleovestibular ganglion and the invasion of the otic vesicle by the neurites. The study of the neuronotrophic interactions in the inner ear is then applied on more mature auditory neurons. In the 5 day-old rat cochlea, we also show the release by the central and the peripheral targets of a trophic activity allowing the survival of the afferent auditory neurons. These neuronotrophic factors may play an important role in the secondary degeneration of the auditory neurons following an injury of the Corti's organ or of the central target. The effect of NGF is also investigated on these neurons and we demonstrate that NGF has a neuritogenic but not a survival promoting effect on the 5 day-old rat afferent auditory neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Effect of complement binding on a solid-phase immunometric TSH assay.

The binding of serum thyrotropin (TSH) to plastic beads coated with a monoclonal antibody to human TSH was inhibited unless EDTA was present during the incubation. The inhibitory factor in serum was heat labile, and its effect could be abrogated by the addition of human albumin-anti-albumin immune complexes. Subsequently it was shown that the antibody-coated beads were able to bind the first component of complement, C1q, and that this binding was inhibited by addition of albumin-anti-albumin complexes. The results show that a surface coated with a monoclonal murine antibody is able to bind complement, and that binding of complement may interfere in solid-phase immunometric assays.

Antibodies, Monoclonal↗
PubMed1988

Aluminum-containing emboli in infants treated with extracorporeal membrane oxygenation.

We found fibrin thrombi or thromboemboli at autopsy in 22 of 23 infants with respiratory failure who had been treated with venoarterial extracorporeal membrane oxygenation (ECMO). In addition, distinctive basophilic aluminum-containing emboli were found in 12 of the infants; the distribution of these emboli was similar to that of the thromboemboli, except that an aluminum-containing embolus was found in a lung in only 1 infant. Sixteen infants had pulmonary thrombi or thromboemboli. We also found friable aluminum-containing concretions adhering loosely to the mixing rods of heat exchangers that had been used to warm the blood flowing through the ECMO circuit; such concretions were not present on unused mixing rods. We propose that these aluminum-containing concretions developed as the silicone coating of the heat exchanger wore away and aluminum metal was exposed to warm, oxygenated blood and that fragments of aluminum-containing concretions formed emboli. This hypothesis is supported by the fact that aluminum-containing emboli were generally not present in the lungs, which are bypassed by ECMO. Although infarcts were found in 16 of the 23 infants, we cannot be certain whether any of the infarcts were caused by the aluminum-containing emboli.

Aluminum↗
PubMed1988

Monoclonal antibodies to the 27-34K insulin-like growth factor binding protein.

Monoclonal antibodies were prepared against the 27-34K insulin-like growth factor (IGF)-binding protein purified from human placenta/decidua and designated placental protein 12 (PP12). Four different antibodies were characterized. Each recognized the major band at 32K on immunoblots of the purified PP12 preparation and amniotic fluid. In liquid phase RIA, IGF-I did not affect the binding of [125I] PP12 to one antibody (Mab 6303), it slightly increased the binding to two antibodies (Mab 6301 and 6304), and it slightly decreased the binding to one antibody (Mab 6302). All antibodies immunoprecipitated the cross-linked PP12-[125I] IGF-I complex, but Mab 6302 considerably less effectively than the others. Preincubation of PP12 with Mab 6302 completely inhibited the binding of [125I] IGF-I to PP12, whereas preincubation with Mab 6303 had no effect, and Mab 6301 as well as Mab 6304 increased it. These results suggest that Mab 6302 binds to an epitope at or near to the IGF-binding site, whereas the other antibodies react at other sites of the PP12 molecule. Conformational changes in PP12 probably account for the IGF-I-induced increase in the binding of Mabs 6301 and 6304 to [125I] PP12, and vice versa, for Mabs 6301- and 6304-induced increase in the binding of [125I] IGF-I to PP12.

Antibodies, Monoclonal↗
PubMed1988

Chronic HIV encephalitis--I. Cerebrospinal fluid diagnosis.

To establish a reliable procedure for the early detection of central nervous system involvement in HIV infection, paired cerebrospinal fluid and serum samples of 59 patients were analysed. Fifteen were HIV antibody positive without clinical symptoms (stage I), 12 had lymphadenopathy syndrome or AIDS-related complex (stage II), and 32 had AIDS (stage III). Intrathecal synthesis of HIV antibodies was determined by a modified ELISA. Antibodies in CSF and serum were evaluated at identical immunoglobulin G levels to correct for the actual blood-CSF-barrier permeability. A CSF/serum quotient above 1.5 is indicative of intrathecal antibody synthesis, which was found in 47% of the patients in stage I, 67% in stage II, and 84% in stage III. These findings indicate an early and frequent invasion of the CNS.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Chronic HIV encephalitis--II. Clinical aspects.

Combined medical, neurological, and serological investigations were carried out in 59 patients infected with human immunodeficiency virus (HIV). In stage I clinical and neuropsychiatric testing did not reveal evidence for HIV encephalitis as diagnosed by local antibody production in CSF. Neuropsychiatric abnormalities, brain atrophy, memory and cognitive impairment reliably indicated HIV encephalitis in later stages. The commonest symptoms were cerebellar and brainstem signs, followed by dementia. Epileptic fits and hemiparesis always were associated with cerebral toxoplasmosis. A polyneuropathy was frequently found but other causes have to be considered.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Impaired immune function in obstructive jaundice.

Sepsis is a common and occasionally lethal complication of obstructive jaundice. The reasons for this increased susceptibility to infection are unknown. This study examines lymphocyte and reticuloendothelial (RES) function in animals with obstructive jaundice. Twelve New Zealand white rabbits (3-4 kg) were studied. Lymphocyte function was evaluated in six rabbits by phytohemagglutinin (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM) stimulation. In six animals, hepatic RES function was assessed by calculating the phagocytic index (PI) using the disappearance of 99Tc sulfacolloid (5 mg/kg) iv. After baseline studies, the common bile duct was divided and ligated. The above studies and serum bilirubin were repeated at 3 weeks. Obstruction was then relieved by cholecystojejunostomy (CJ) and RES studies repeated monthly x 6. Preobstructive lymphocyte function showed a stimulation index ratio (log) of 0.85 +/- 0.25 for PHA, 0.75 +/- 0.3 for Con A, and 0.71 +/- 0.25 for PWM. With biliary obstruction, the values fell to -0.23 +/- 15 (P less than 0.006), -0.31 +/- 0.12 (P less than 0.006), and -0.29 (P less than 0.006), demonstrating impaired lymphocyte function. When tested lymphocytes were mixed with control pooled rabbit serum, however, no lymphocyte impairment was noted. Baseline hepatic PI was 6.02 +/- 0.18 and fell to 3.79 +/- 0.33 with obstruction (P less than .01) and remained low at (3.20 +/- 0.14) 1 month (P less than 0.01) and (3.33 +/- 0.23) at 3 months (P less than .01), after CJ but returned to normal (8.04 +/- 0.97) at 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Immunocytochemical analysis of immunoglobulin-containing cells in CSF and blood in inflammatory disorders of the central nervous system.

Cells containing immunoglobulins G, A, and M were evaluated in paired cerebrospinal fluid (CSF) and peripheral blood (PB) samples. These were obtained from 12 patients with bacterial meningitis, 14 patients with viral meningitis, 6 cases of lymphocytic meningoradiculitis (LMR), 10 cases of multiple sclerosis (MS), 6 cases of herpes zoster ganglionitis and 27 patients with non-infectious disorders of the CNS. PB cells from 20 healthy donors served as controls. Using alkaline phosphatase (AP)-conjugated antibodies to human immunoglobulin (Ig) G, A, and M in a carrageenan solution it was possible to demonstrate repeatedly intracytoplasmic Igs over more than 1 year without any detectable loss of specificity and staining intensity. Immunoglobulin-containing cells (ICC) could be detected in the CSF of 96% of patients with inflammatory diseases of the central nervous system (CNS) or with MS but not in the control cases.

Antibodies, Monoclonal↗
PubMed1988

Detection and purification of a recombinant human B lymphotropic virus (HHV-6) in the baculovirus expression system by limiting dilution and DNA dot-blot hybridization.

A recombinant virus Ac373-HB was detected and purified from the transfection mixture of wild type and recombinant virus in the baculovirus expression system using a combination of limiting dilution and DNA dot-blot hybridization. This method allows for a quick and convenient way of detection and purification of recombinant virus without the need to use a plaque purification step. It is generally applicable to other expression systems besides the baculovirus system described here.

B-Lymphocytes↗