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Biomedical subjects

J Andersson

Publications and source records attributed to J Andersson.

At least 163 records · Page 9Linked to original sources
PubMed1996

Profound reduction of mature B cell numbers, reactivities and serum Ig levels in mice which simultaneously carry the XID and CD40 deficiency genes.

It has been known for some time that single mutant nude or CD40T mice have apparently normal numbers of cells in the precursor compartments of bone marrow and the mature B cell compartments of the periphery. X-linked immunodeficiency (XID) mice are deficient only in some of the sIgM+sIgD+ B cells. We have investigated further the contributions of the xid mutation, of the T cell deficiency of nude of the inability of CD40T cells to cooperate with T cells in the generation of the precursor and the mature B cell compartments in mice. Double mutant XID/nu and XID/CD40T mice have precursor B cell compartments that are no more deficient than the single mutant XID mice. However, the peripheral B cell compartments of both XID/mu and XID/CD40T are even more deficient than those of single mutant XID mice. While 10% of the peripheral B cells of wild-type or CD40T, one-third of XID and half of XID/nu mice turn over rapidly, as many as three-quarters of those in XID/CD40T are short-lived. Total numbers of sIgM+sIgD+ B cells in the spleen are at best 10-15% of normal mice at 6-8 weeks of age in XID, XID/nu and XID/CD40T mice. They remain that low at 3 months of age in XID/CD40T mice, while in XID mice these peripheral B cells slowly build up in numbers with age. As expected, double mutant XID/CD40T mice do not respond to the T-dependent antigen keyhole limpet hemocyanin. Only the responses to the T-independent type I antigen, TNP-lipopolysaccharide (LPS), appear to be normal. In vitro, their splenic B cells respond poorly to LPS or to IgM-specific antibody in either the absence or presence of cytokines. Most notably, serum IgM, IgG2b or IgG3 levels are severely depressed, while IgG1, IgG2a and IgA levels are < 10 micrograms/ml. These results suggest a model of mature B cell development in which the peripheral, mature B cell compartments are generated in two parallel, not tandemly organized pathways. They could be selected and/or stimulated at the transition from immature to mature B cells: in btk controlled or in CD40 controlled ways.

Animals↗
PubMed1996

Verbal information-processing capabilities and cochlear implants: implications for preoperative predictors of speech understanding.

In this study, we examined preoperative verbal cognitive capacity in 11 deafened adults who were cochlear implant candidates and reexamined level of speech understanding after 6-8 months' experience with the implant. Verbal cognitive performance in the implant group was compared in a group of normal hearing subjects and in nonimplanted group of deafened adults. The three groups performed on par with each other with an exception: The individuals in the cochlear implant group and the nonimplanted group of deafened adults performed significatly worse than those of normal hearing in tasks in which use of internal speech is a key feature (i.e., rhyme judgement and lexical decision tasks). Postoperative observations of the implanted individuals' level of speech understanding suggest that it is possible to predict the level of speech understanding by means of a properative cognitive assessment. The characteristics of three verbal cognitive abilities prove to be critical indicators of 6 - 8 months' postoperative outcome: internal speech functioning, speed of verval information processing, and working memory capacity - the first factor proved the most decisive. We discuss the results with respect to direct versus indirect predictors of outcomes from cochlear implant operations and the effect of auditory deprivation on deafened adults' capability to process auditory information.

Journal Article↗
PubMed1996

Simultaneous intracerebral microdialysis and positron emission tomography in the detection of ischemia in patients with subarachnoid hemorrhage.

Intracerebral microdialysis (MD) was applied in patients with subarachnoid hemorrhage. The regional CBF, the CMRO2, and oxygen extraction ratio (OER) were measured with simultaneous positron emission tomography (PET). The aim was to directly correlate alterations in dialysate levels of energy-related metabolites (lactate, lactate/pyruvate ratio, hypoxanthine) and excitatory amino acids (EAAs) (glutamate and aspartate) to the energy state in the MD probe region as determined by PET. Regional ischemia was defined according to Heiss et al. and Lassen (Heiss et al., 1992; Lassen, 1966). Whole-brain ischemia was considered present when the OER for the whole brain exceeded the mean whole-brain OER + 2 SD of six reference patients. In general, the presence of whole-brain ischemia and/or regional ischemia within the region of the MD probe was associated with increased levels of energy-related metabolites and EAAs retrieved by MD. Increased levels of energy-related metabolites and EAAs were only occasionally seen when PET did not show any signs of ischemia or when signs of regional ischemia were found remote from the MD probe region. Thus, the energy-related metabolites and EAAs may be used as extracellular "markers" of ischemia. PET may be of use in defining critical ischemic regions (tissue at risk) where the MD probe can be inserted for chemical monitoring.

Aged↗
PubMed1996

Fungal pneumonia: the predominant lung infection causing death in children undergoing bone marrow transplantation.

The study included 6 children (aged 4-14 years) receiving a conditioning regimen for bone marrow transplantation (BMT) and 14 children (aged 2 14 years) with bone marrow transplants (13 allogeneic, 1 autologous). The children underwent flexible fibre-optic bronchoscopy (FFB) with bronchoalveolar lavage during 6 and 17 episodes of pneumonia, respectively. The aim was to compare the results of the two groups with respect to bronchoscopy findings, pneumonia-causing agents and outcome. During the conditioning regimen, the aetiological agents were recovered by bronchoscopy in 1/6 (17%) episodes and revealed by autopsy in another episode. In three episodes where the aetiology was uncertain, bacterial pneumonia was suspected in two, and Candida pneumonia in one. In episodes after transplantation the aetiological agents were recovered from bronchoscopy material in 14/17 (82%) patients. Autopsy confirmed the premortal diagnosis in the four children who died. In three episodes, bacterial pneumonia was clinically suspected. Based on clinical manifestations, FFB and autopsy findings, bacterial and fungal pneumonia were the most common diagnoses both during conditioning and after BMT. Fungal pneumonia was the most common cause of death in both groups.

Adolescent↗
PubMed1996

Evidence for the presence of streptococcal-superantigen-neutralizing antibodies in normal polyspecific immunoglobulin G.

Recently we demonstrated that normal polyspecific immunoglobulin given intravenously (IVIG) and plasma samples from patients treated with IVIG neutralize the mitogenic and cytokine-inducing activities of group A streptococcal (GAS) superantigens. Here we investigated whether this neutralizing activity is mediated by antibodies to these superantigens. IVIG and plasma samples collected from a patient with GAS necrotizing fasciitis post-IVIG infusions markedly inhibited the mitogenic activity elicited by the streptococcal pyrogenic exotoxins SpeB and SpeC, as well as by GAS culture supernatant. Immunoblot analysis showed marked increases in the levels of antibodies to SpeC and proteins in the GAS culture supernatant in post-IVIG over those of pre-IVIG plasma samples. Removal of antisuperantigen antibodies in IVIG by adsorption to SpeC- and GAS culture supernatant-coupled Sepharose markedly reduced the neutralizing ability of IVIG against respective stimuli. The neutralizing activity was totally recovered in the eluted antibodies. By contrast, although pre- and post-IVIG plasma samples contained antibodies to SpeA, these antibodies did not block the activity of this superantigen. Nonspecific immunomodulatory activity of IVIG was ruled out because neither the IVIG nor the affinity-purified antibodies significantly inhibited the response to the polyclonal T-cell mitogen phytohemagglutinin A. These data provide direct evidence that the neutralizing activity in IVIG, and in patient plasma samples following IVIG treatment is mediated by antibodies to superantigens and indicate that the quality rather than the quantity of these antibodies may be more clinically relevant.

Adult↗
PubMed1996

Local entrapment of interferon gamma in the recovery from Shigella dysenteriae type 1 infection.

In healthy controls (n = 8) living in shigella endemic areas, accumulation of interferon gamma (IFN gamma) in the epithelial lining was seen in the rectal tissues. At the single cell level, however, few or no IFN gamma protein producing cells or mRNA expressing cells were detected at that site indicating the involvement of the whole large intestine in the production of IFN gamma in controls. Persistent numbers of IFN gamma producing cells were detected in the rectum of patients with Shigella dysenteriae type 1 infection (n = 8) throughout the course of disease with a tendency to increase in the convalescent stage. A significantly increased extra cellular deposition of secreted IFN gamma in tissue was seen in convalescence when compared with the acute stage (p < 0.05). In addition, enzyme immunoassay showed increased stool concentration of IFN gamma in patients at the convalescent stage as well as in healthy controls. In situ hybridisation confirmed the results by showing increased frequency of IFN gamma mRNA containing cells at the late stage of the disease (p < 0.05). Extensive message for IFN gamma was evident in cells in the lamina propria with no detectable transcripts in the surface epithelium. A colocalisation of IFN gamma with the IFN gamma receptor expression, predominantly found in the epithelial lining was detected by immunohistochemistry. Semiquantitative evaluation by computerised image analysis showed a gradual increased expression of IFN gamma and its corresponding receptor in the convalescent stage of shigellosis. This suggested progressive entrapment and binding of IFN gamma to its specific receptor at the local site. The enhanced surface expression of IFN gamma receptor evident at the convalescent stage of shigellosis was comparable to the constitutive level of expression in the healthy subjects. Thus, immunity to shigellosis correlated to up-regulation of IFN gamma production and expression of IFN gamma receptor.

Acute Disease↗
PubMed1996

Positron emission tomography in the diagnosis and staging of urinary bladder cancer.

PURPOSE: Evaluation of positron emission tomography (PET) using (18)fl 18F-2-fluoro-2-deoxy-D-glucose (18FDG) and L-methyl-11C-methionine in the diagnosis and staging of urinary bladder carcinoma. MATERIAL AND METHODS: Twenty-three patients with biopsy-proven urinary bladder carcinoma were examined with PET after intravenous injection of 11C-methionine; 2 were also examined with 18FDG. The results from the PET investigations were compared with CT or MR findings and TNM classification before and after treatment. RESULTS: The urinary excretion of 18FDG prevented distinction of the primary tumour from the surrounding tracer. With 11C-methionine it was possible to detect 18/23 primary tumours. A trend was seen, suggesting that the higher the uptake values of 11C-methionine in the tumour, the greater the tumour stage. CONCLUSION: It is possible to visualize urinary bladder tumours larger than 1 cm in diameter with PET using (11)C-methionine, but the value of the method in the staging of the lesions is not superior to conventional methods.

Aged↗
PubMed1996

The production of immunoregulatory cytokines is localized to the extrafollicular area of human tonsils.

The localization and production at the single cell level of 19 different human cytokines, IL-1 alpha, IL-1 beta, IL-1ra, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, IL-10, IL-13, TNF alpha, TNF beta, IFN gamma, GM-CSF, G-CSF, and TGF beta 1-3, were studied in cryopreserved tonsillar tissue using immunohistochemical staining. The cytokine producing cells, with the exception of IL-1 expressing cells, had a characteristic morphology due to the accumulation of cytokine onto the Golgi organelle. The production of each cytokine was localized to specific compartments in tonsillar tissue sections from children with tonsillar hypertrophy or recurrent tonsillitis in the resting state. Immunoregulatory cytokines such as IL-2, IL-3, IL-4, G-CSF, GM-CSF and TGF beta were produced in the extrafollicular area and entrapped on the cell membranes as well as in pudels in the extracellular matrix surrounding the producer cells. The dominating cytokines both in tissues from recurrent tonsillitis and tonsillar hypertrophy were GM-CSF, G-CSF, and TGF beta 1-3 which were synthezised predominantly in the reticular crypt site. IL-1 alpha, beta and IL-1ra, on the other hand, were localized to the surface and crypt epithelium and to scattered regions in the extrafollicular area. IL-2, IL-6, IFN gamma and IL-10 were found much more often in sections obtained from recurrent tonsillitis tissue compared with those from tonsillar hypertrophy. Reversely, an excessive production of IL-4 was noted in tonsillar hypertrophy compared with that in recurrent tonsillitis. Thus, concomitant production of multiple cytokines was evident with similarities but also differences in cytokine pattern between the two groups studied. The data suggest that T-cell mediated B-cell activation and differentiation take place in the extrafollicular area. Children with recurrent tonsillitis had a higher amount of B-cells and monocytes compared with children with tonsillar hypertrophy. However, the number of CD3, CD4, CD8 or cytoplasmic Ig-positive cells did not differ between the two groups.

Cell Movement↗
PubMed1996

Lack of T-helper lymphocytes in BAL fluid from a HIV-negative patient with recurrent non-tuberculous mycobacterial lung infections.

We describe here a previously healthy, 42 year old, HIV-negative woman. Following a seemingly successful 2-year antimycobacterial regimen for a lung infection caused by Mycobacterium avium/intracellulare she acquired a lung infection caused by M. chelonei. Characterization of alveolar cells from bronchoalveolar lavage fluid using flow cytometry revealed a total lack of T-cell subset CD4+ helper lymphocytes in spite of a normal proportion of the CD3+ and CD4+ T-cells in peripheral blood. The levels of Th2 cytokines such as IL-4, TGF-beta and G-CSF were higher in the patient's alveolar cells than in the cells of 4 healthy controls. This imbalance of cells and cell cytokines may contribute to the patient's susceptibility for non-tuberculous mycobacteria and her failure to eradicate these microorganisms.

Adult↗
PubMed1996

Intravenous immune globulin affects cytokine production in T lymphocytes and monocytes/macrophages.

Immune globulin for intravenous use (IVIG) has been used in many inflammatory conditions due to its immunomodulatory potential. The effector mechanisms are incompletely understood. This study dealt with the effects of IVIG on cytokine production in vitro. Cytokine synthesis was identified at the single-cell level using cytokine-specific MAb and indirect immunocytochemical techniques. Peripheral blood mononuclear cells (PBMC) were stimulated for 96 h by immobilized anti-CD3 MAb or by a combination of a protein kinase C activator (PMA) and a calcium ionophore (ionomycin). The addition of IVIG (6 mg/ml) caused a marked inhibition of proliferation and blast transformation despite unaffected cell survival. Anti-CD3-stimulated cultures containing IVIG exhibited a significant inhibition of production of T-cell derived lymphokines IL-2, IL-10, TNF-beta, IFN-gamma and TNF-alpha (made by both monocytes and T cells), while synthesis of the monokine IL-8 was significantly increased. The expression of IL-2 receptors was significantly suppressed. Similar but transient inhibition of most T-cell products (IL-2, IL-3, IL-4, IL-5, IL-10, TNF-beta and GM-CSF) was noted in the PMA/ionomycin-containing cultures. In contrast, no effects were found on IFN-gamma or TNF-alpha production. The superantigen streptococcal pyrogenic exotoxin-A (SPE-A) induced vigorous cell activation and extensive cytokine synthesis. IVIG was added either at the beginning or 24 h after the initiation of cultures in order to elucidate the importance of direct toxin-neutralization. Addition of IVIG from the beginning of cultures induced a strong reduction of blast transformation and an almost complete inhibition of lymphokine production, in particular of IFN-gamma and TNF-beta. Supplementation with IVIG 24 h after initiation of cultures also led to a significant decrease in lymphokine synthesis. Monokine production (IL-1 alpha, IL-1 beta, IL-1ra, IL-6 and IL-8) was either unaffected or even increased. These two facts argue against direct antigen-neutralization as being the only mechanism at work. However, in IVIG-exposed PBMC stimulated with LPS, IL-6 production was significantly reduced. A significant upregulation of IL-1ra was noticed in unstimulated PBMC cultured with IVIG. The results in all the experiments did not indicate a cytotoxic effect by IVIG on cell survival and the production of certain cytokines were unaffected. Instead, the authors believe that the results suggest a previously little examined functional link where the humoral immune response may have direct immunoregulatory effects on the cellular immune system.

Adult↗
PubMed1996

Clinical and immunological considerations in Epstein-Barr virus-associated diseases.

Despite the fact that nucleoside analogues, such as aciclovir and ganciclovir, and DNA-polymerase inhibitors, such as foscarnet, have a proven antiviral effect on oropharyngeal-Epstein-Barr virus (EBV) replication, they have been unable to show any effect on the severity or duration of infectious mononucleosis (IM), a condition for which there is currently no established treatment. Clinical symptoms may be due to an EBV-induced polyclonal humoral, as well as cellular, immunoreactivity with limited pathology caused by viral replication itself. However, despite an extensive immune response, 90% of tested IM patients (n = 36) had a spontaneous outgrowth of in vivo EBV-infected B-lymphocytes at onset of disease, indicating lack of specific EBV-restricted cellular cytotoxicity at this time. Establishment of an EBV-specific T-lymphocyte response occurred 90-180 days after onset of disease (human leukocyte antigen-restricted cytotoxicity against EBV-infected B-cells). Thus, development of a specific cytotoxic response was a gradual and slow process. Assessment of cytokine pattern, at the single cell level, was performed by immunocytochemical technique and by enzyme-linked immunosorbent assay. This revealed an increased production of interleukin (IL)-2, interferon (IFN)-gamma, IL-6 and tumour necrosis factor (TNF) beta in all IM patients. Those with disseminated disease were characterized by lack of IFN-gamma production. This loss was selective since in vitro stimulation with superantigen, such as streptococcal pyrogenic exotoxin A, induced a normal response. These patients lacked signs of EBV-specific T-cell cytotoxicity in vitro. Treatment with intravenous or subcutaneous IFN-gamma, 1.5 MU every second day, in combination with intravenous immunoglobulin G (0.5 g/kg three times per week) and oral aciclovir, 800 mg 5 times daily, has shown promising results in some patients. Cytokine production in tonsil tissue in 4 patients with fulminant IM and respiratory tract obstruction showed a concomitant expression of IL-2, IFN-gamma, IL-6, TNF beta, transforming growth factor (TGF) beta 1-3, granulocyte colony stimulating factor, granulocyte macrophage colony stimulating factor, IL-4 IL-1alpha, IL-beta and TNF alpha. The number of IL-2, IFN-gamma, IL-6 and TNF beta producing cells was significantly higher compared to tonsil tissue obtained from children with tonsillar hypertrophy. Thus, IM is associated with extensive local cytokine production. It is suggested that this extensive cytokine production is closely involved in the pathology of IM and that patients with atypical IM have a dysregulation in the cytokine network. However, the mechanism by which EBV-infected B-lymphocytes triggers this cytokine cascade is still unknown. These findings show the need for evaluation of patients with immunodeficiency and EBV-induced lymphoproliferative disorders and perhaps the introduction of new immunoregulatory treatment strategies.

Cells, Cultured↗
PubMed1995

Affective and attentive neural networks in humans: a PET study of Pavlovian conditioning.

Using positron emission tomography (PET) and [15O]butanol we studied regional cerebral blood flow (rCBF) to a visual snake stimulus before and after classical conditioning with an unconditioned electric shock delivered to the right hand. Measures of heart rate, electrodermal activity, state anxiety and subjective distress confirmed classical conditioning of physiological and subjective responses. Subcortically, conditioning increased rCBF bilaterally in the ventromedial thalamus, the posterior hypothalamus and the central grey of the midbrain. Cortically, rCBF increased in the left anterior and posterior cingulate gyrus, the left primary somatosensory cortex, the left premotor cortex and bilaterally in parietal areas. Thus, the functional organization of classical conditioning in humans involves autonomic, affective and attentive brain mechanisms.

Adult↗
PubMed1995

Generation of the glycyl radical of the anaerobic Escherichia coli ribonucleotide reductase requires a specific activating enzyme.

The anaerobic ribonucleotide reductase from Escherichia coli contains a glycyl radical as part of its polypeptide structure. The radical is generated by an enzyme system present in E. coli. The reductase is coded for by the nrdD gene located at 96 min. Immediately downstream, we now find an open reading frame with the potential to code for a 17.5-kDa protein with sequence homology to a protein required for the generation of the glycyl radical of pyruvate formate lyase. The protein corresponding to this open reading frame is required for the generation of the glycyl radical of the anaerobic reductase and binds tightly to the reductase. The "activase" contains iron, required for activity. The general requirements for generation of a glycyl radical are identical for the reductase and pyruvate formate lyase. For the reductase, the requirement of an iron-containing activase suggests the possibility that the iron-sulfur cluster of the enzyme is not involved in radical generation but may participate directly in the reduction of the ribonucleotide.

Amino Acid Sequence↗
PubMed1995

Effects of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin on the dopaminergic and cholinergic receptors as evaluated by positron emission tomography in the Rhesus monkey.

The effects of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP) on the central cholinergic and dopaminergic systems in the Rhesus monkey brain were investigated by positron emission tomography (PET) with the muscarinic cholinergic receptor ligands (N-[11C]methyl-benztropine) and dopaminergic receptor ligands selective for D1, D2, and D3 subtypes ([11C]SCH23390, N-[11C]methyl-spiperone, and (+)[11C]UH232, respectively). None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP used significantly affected the regional cerebral blood flow (rCBF as determined by Raichle's H(2)15O method), and 10 mg/kg of R-THBP had little effect on the regional cerebral metabolic rate of glucose (rCMRglc) in the Rhesus monkey brain, as assessed by the graphical [18F]fluoro-deoxyglucose method. The effect of R-THBP on the muscarinic cholinergic system was dose dependent; while 3 mg/kg of R-THBP did not significantly alter the uptake ratio of N-[11C]methylbenztropine in several brain regions to that in the cerebellum, 10 and 30 mg/kg of R-THBP significantly reduced the uptake ratio in the thalamus, as well as in the frontal and temporal cortices. None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP tested affected [11C]SCH23390 (dopamine D1 receptor) binding. However, the k3 value for N-[11C]methyl-spiperone (dopamine D2 receptor) binding, which represents the association rate X Bmax value, was significantly decreased in the striatum. The uptake ratio of (+)[11C]UH232 (dopamine D3 receptor) in the striatum to that in the cerebellum was also decreased by administration of R-THBP (3 and 30 mg/kg i.v.). These findings suggest that R-THBP acts on dopamine D2 and D3 receptors selectively without markedly affecting dopamine D1 receptor binding. Furthermore, the changes in cholinergic and dopamine D2 and D3 receptors in vivo can not be attributed to a change in rCBF but may depend on the action of R-THBP.

Animals↗
PubMed1995

Positive and negative selection events during B lymphopoiesis.

Early in B-cell development, large numbers of cells have to be generated, each of which expresses only one type of B-cell receptor (i.e. Ig) on its surface. This is achieved by the surface expression of a pre-B cell receptor containing a mu heavy chain/surrogate light chain which differentially provides signals for two responses of precursor B cells at this stage of development. On the one hand, it signals inhibition of further rearrangements of variable heavy chain to diverse-joining heavy chain loci to achieve allelic exclusion at the heavy-chain locus. On the other hand, it signals proliferative expansion by factors between 20 and 100. Later in B-cell development, tolerance to autoantigens must be established and maintained. Tolerance is achieved by developmental arrest and induction of secondary light-chain gene rearrangements in those IgM+ immature B cells that are reactive to autoantigens presented in the primary B-cell generating organs. Even later in development, when mature surface (s)IgM+/sIgD+ B cells encounter autoantigens presented to them in the periphery, either deletion or anergy of the autoantigen-reactive cells occurs. Anergic cells have a sIg-dependent, sIg-proximal defect in signaling and are short-lived. Anergy can be broken in vitro by polyclonal activation via ligation of CD40 in the presence of IL-4. A small part of the remaining immature B cells not reactive to autoantigens are selected to become mature, antigen-reactive sIgM+/sIgD+ B cells. Molecules which might guide such positive selection of B cells still remain to be identified.

Animals↗
PubMed1995

Cytokine secretion in acute shigellosis is correlated to disease activity and directed more to stool than to plasma.

Stool and plasma cytokine levels in 60 adults with acute shigellosis were studied by EIA at various intervals (0-45 days) after onset of diarrhea. Cytokine levels correlated with severity of disease. Significantly higher levels of proinflammatory cytokines peaked at onset of disease in stool of patients with severe disease (P < .05). In contrast, interferon-gamma (IFN-gamma) levels, depressed at disease onset, progressively increased during the convalescent stage. Concomitantly obtained plasma cytokine levels were 100 times lower than levels in stool. Controls in Shigella-endemic areas (n = 42) had persistently significantly higher levels of IFN-gamma and interleukin-1 receptor antagonist in both stool and plasma. The lack of host defense activity against shigellosis may be linked to delayed recovery of IFN-gamma. This cytokine may play an important role in elimination of the infection and development of immunity against shigellosis.

Acute Disease↗