Biomedical subjects

J Albert

Publications and source records attributed to J Albert.

At least 145 records · Page 8Linked to original sources

PubMed1992

Significance and quantitative analysis of von Willebrand factor in human platelets.

The von Willebrand factor (vWF) is found in plasma and in platelets. The concentration and multimeric composition of the vWF in platelets of 160 patients with bleeding tendency were examined since very little is known about the platelet vWF. For quantitative analysis of the platelet vWF, a modified ELISA was established. A reference range from 70%-130% of platelet vWF concentration considered normal was established by examining 80 healthy blood donors. 16.9% of the 160 patients showed a decreased vWF concentration in platelets only, while all the other coagulation parameters were normal. 3 of our patients belong to the same family and suggesting an autosomal dominant genetic transmission for the von Willebrand disease type 1-3. The data also suggests, that a quantitative and qualitative analysis of the vWF in plasma and platelets is required for an exact diagnosis of the von Willebrand disease.

Blood Donors↗

PubMed1992

Acute inflammatory response to cowpox virus infection of the chorioallantoic membrane of the chick embryo.

The chick embryo chorioallantoic membrane was used to study the acute inflammatory response in the absence of contributions from the immune system. In preliminary experiments, lesions of wild-type cowpox virus strain Brighton (CPV-BR) and a 38K gene deletion mutant of CPV-BR (CPV-BR.D1) were compared with vaccinia virus (strains WR and Copenhagen), fowlpox virus, laryngotracheitis virus, and infectious tenosynovitis virus, and were ranked for degree of induced inflammation. The maximal and minimal inflammatory responses were observed with CPV-BR.D1 and CPV-BR viruses, respectively. CPV-BR.D1 lacks a 38K gene which encodes an anti-inflammatory 38-kDa protein that has homology to SERPINs. The kinetics and character of the inflammatory response were examined further in the wild-type CPV-BR and mutant CPV-BR.D1 infections using cell counts, electron microscopy, and assays for inflammatory cell activation. CPV-BR virus infection rapidly spread through the ectoderm, uniformly infecting all cells with the production of large amounts of virions and viral-induced cytopathic effect, but evoking little or no inflammatory response until 144 hr p.i. The CPV-BR.D1 infection, on the other hand, was rapidly contained by a dexamethasone-sensitive inflammatory response mainly of activated heterophils which was advanced by 36 hr p.i. Both infections resulted in disseminated disease with similar numbers of liver lesions and only a slight difference in the LD50, with the CPV-BR.D1 values being higher than that for CPV-BR virus. In this model, the acute inflammatory response alone is unable to prevent disseminated disease and associated mortality.

Acute Disease↗

PubMed1992

Ugandan HIV-1 V3 loop sequences closely related to the U.S./European consensus.

The third variable (V3) loop of the human immunodeficiency virus type 1 (HIV-1) envelope protein is an important determinant for virus neutralization and cell tropism. V3 loop sequences from uncultured lymphocytes obtained in 1990 from 22 Ugandan HIV-1-infected patients could, with the exception of two patients' sequences, be divided into two groups (A and B) on the basis the V3 loop size and sequence. The V3 loop consensus sequences from both groups showed a high degree of homology to a U.S./European consensus, a characteristic also reflected by the results of peptide serology. In the case of group B the difference in sequence was only five amino acids. In contrast, the V3-flanking regions for both groups showed greater homology to an earlier (1986/1987) Ugandan consensus. The discovery of these two new Ugandan V3 loop genotypes, which are closely related to the U.S./European consensus, has implications for the understanding of the evolution of HIV-1 and for the future design of a vaccine for use in Africa.

Amino Acid Sequence↗

PubMed1992

Ligament strain and ankle joint opening during ankle distraction.

To determine the efficacy of ankle distraction and to investigate possible complications of the procedure, the strain on four ankle ligaments and the tibiotalar joint opening resulting from distraction force and various foot positions were studied. We mounted strain gauges on the deltoid, calcaneofibular, tibiofibular, and anterior talofibular ligaments of six fresh human cadaver ankles. An Acufex ankle distractor was used to apply forces of 45, 90, 135, and 180 N at 20 degrees dorsiflexion, neutral, and 10 degrees plantar flexion. The ankle distractor proved to be effective in opening the joint space for better visualization, but complications of pin bending, excessive ligament strain, and bony destruction did occur within the clinically recommended range. Based on the observed results, the safest method of distraction was to use forces < 135 N in the neutral position.

Ankle Joint↗

PubMed1992

Blood-derived macrophages produce IL-1, but not TNF-alpha, after infection with HIV-1 isolates from patients at different stages of disease.

Interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF-alpha) are not constitutively produced by human mononuclear phagocytes. In the present study we have investigated the production of these cytokines in human blood-derived macrophages (BDM) after infection with 16 primary HIV-1 blood isolates obtained from individuals at different stages of disease. In addition, we monitored the replicative capacity of these primary isolates in blood-derived macrophages over a 3-month period. Production of IL-1 alpha was detected in two cultures, IL-beta was positive in two other cultures, and both IL-1 alpha and IL-beta were present in three additional macrophage cultures. IL-1 alpha production was also detected in BDMs infected with the laboratory strain HIV-1 IIIB. In contrast, TNF-alpha was not found in any of the culture supernatants tested. All primary HIV-1 isolates used in these experiments were able to infect BDM productively irrespective of the clinical stage of the patients at the time of virus isolation. The production of IL-1 was mostly found in chronically infected cultures displaying low levels of HIV-1 replication. These results indicate that macrophages tropism is a general feature of all HIV-1 isolates. Furthermore, release of IL-1 by mononuclear phagocytes upon HIV-1 infection may contribute to the pathogenesis of HIV-1 related diseases.

Blood Cells↗

PubMed1992

Loss of synergistic response to combinations containing AZT in AZT-resistant HIV-1.

The use of combination chemotherapy for the treatment of HIV-1 infection offers promise for overcoming the problems of toxicity and development of resistance. Primary HIV-1 isolates from three patients before and after treatment with azidothymidine (AZT) were examined for sensitivity to AZT and synergistic response to three different combinations of drugs: AZT+fluorothymidine (FLT), AZT+dideoxyinosine (ddI), and FLT+ddI. All three patients initially harbored AZT-sensitive virus, but posttherapy isolates were resistant to AZT. The pretreatment, AZT-sensitive virus from each patient showed synergistic inhibition by the combinations of AZT+FLT, AZT+ddI, and FLT+ddI. In contrast, the posttreatment, AZT-resistant virus showed only addition or antagonism by the combinations containing AZT, whereas the synergistic response to the combination of FLT+ddI was preserved. Our study argues for early intervention with combination chemotherapy, since after development of resistance, AZT no longer showed synergy but addition or antagonism in combination with other drugs. After resistance to AZT has developed, combination chemotherapy not involving AZT may offer advantages over continued mono- or combination therapy involving AZT.

Antiviral Agents↗

PubMed1992

Dynamic changes in HIV-1 quasispecies from azidothymidine (AZT)-treated patients.

The emergence of azidothymidine (AZT)-resistant human immunodeficiency virus (HIV) variants in clinical samples was studied by a direct genomic sequencing method. Sequential lymphocyte samples from four patients, who had been treated with AZT for up to 27 months, were shown to gradually accumulate multiple nucleotide changes, some of which are known to be associated with AZT resistance. Several samples were shown to contain mixtures of wild-type and mutated genomes, indicating gradual rather than sudden changes in the HIV-1 quasispecies. These results demonstrate for the first time that automated solid-phase DNA sequencing is a rapid and useful tool for investigation of antiviral drug resistance and suggest that DNA sequencing may be important in routine clinical diagnostics in the future.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Effect of antithrombin concentrate on haemostatic variables in critically ill patients.

In a controlled pilot study of 32 critically ill patients, we have attempted prospectively to identify laboratory variables which can be used to select and monitor patients on antithrombin (AT) therapy. Patients with plasma AT levels less than 70% of normal were randomized to receive (AT group) or not to receive AT concentrate (non-AT group). The groups did not differ in median age, sex, median APACHE II and TISS scores, number of days spent in the Intensive Care Unit or mortality rate. At the time of inclusion all patients had activated coagulation and fibrinolysis demonstrated as high levels of soluble fibrin, thrombin-antithrombin complexes and fibrin-D-dimers (twice, four and ten times the upper reference range, respectively). In the AT group these levels decreased faster and the prothrombin complex concentration increased more rapidly to normal (i.e. the prothrombin time decreased). The level of C-reactive protein which was high in both groups on inclusion (139 and 98 mg/l, respectively) decreased by 40% in the AT group but did not change in the control group. Our study indicates that laboratory variables normalize faster in seriously ill patients who have activated coagulation and fibrinolysis when they receive AT concentrate and that the variables mentioned above seem to be useful for monitoring the treatment.

Aged↗

PubMed1992

Tumor necrosis factor modulates the inactivation of catecholamine secretion in cultured sympathetic neurons.

Cytokines exert multiple effects on cellular functions. We studied the effects of cytokines on the calcium-dependent release of catecholamines in cultured neurons from neonatal rat superior cervical ganglia. Incubation of sympathetic neurons with recombinant human interleukin-1 beta (0.14-0.7 nM) or recombinant human tumor necrosis factor-alpha (1 nM) for 24-48 h had no effect on the baseline spontaneous release and the initial K(+)-evoked [3H]norepinephrine release, compared with untreated cells. A repeat K(+)-induced depolarization after 6 min resulted in a decrease of [3H]norepinephrine secretion to 69 +/- 5.8% (n = 11) of the initial secretion in recombinant human tumor necrosis factor-treated cells, but not in control cells. The secretory response was restored when the interval between the two K+ challenges was increased to 10 min. We conclude that the diminished secretory response to a repeat stimulus in recombinant human tumor necrosis factor-treated superior cervical ganglia neurons is due to a prolonged recovery from inactivation of secretion in these cells.

Animals↗

PubMed1992

Human immunodeficiency virus type 1 is present in the cerebrospinal fluid of a majority of infected individuals.

Cerebrospinal fluid (CSF) specimens from 63 patients with different severities of human immunodeficiency virus (HIV-1) infection, including asymptomatic virus carriers, were examined for the presence of HIV-1 by using polymerase chain reaction (PCR) and virus isolation. Polyadenylated RNA, presumably associated with virus particles, was extracted and reverse transcribed, and the pol region was amplified in a nested PCR. Virus could be detected in 90% of the CSF specimens examined by PCR, and data on isolation of virus from CSF were in agreement with these figures. In fact, when several CSF specimens from the same individual were studied, HIV-1 could be isolated from 80% of the patients. The presence of the viral RNA in CSF was independent of the clinical stage of infection and of neurological symptoms. These results show that the spread of HIV-1 to the brain represents an early event during infection and occurs in the majority of asymptomatic individuals.

Blood↗

PubMed1992

Persistence of azidothymidine-resistant human immunodeficiency virus type 1 RNA genotypes in posttreatment sera.

The rate of reversion from azidothymidine (zidovudine; AZT) resistance was studied by direct sequencing of human immunodeficiency virus type 1 (HIV-1) virion RNA in sera from four patients who discontinued long-term treatment. Before cessation of treatment, all four patients harbored HIV-1 with multiple mutations reported to confer AZT resistance. In three patients, slow reversions of these mutations starting after 9, 9, and 18 months were detected. The slow reversions indicate that AZT-resistant HIV-1 variants are likely to have an unaltered replicative capacity and pathogenic potential. Furthermore, there were discrepancies between the in vivo RNA sequences and the sequences of virus isolates, indicating that the isolation procedure may select for nonrepresentative virus variants.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Tumor necrosis factor modulates Ca2+ currents in cultured sympathetic neurons.

The effect of recombinant human tumor necrosis factor-alpha (rhTNF) on calcium currents of cultured neurons from neonatal rat superior cervical ganglia (SCG) was studied using whole-cell patch-clamp technique. We found that rhTNF-treated SCG neurons exhibited increased calcium current density without significant alteration in the steady-state parameters of activation and availability. The fraction of the current sensitive to dihydropyridines and omega-conotoxin also remained unchanged. Recovery from slow inactivation of the current, but not recovery from fast inactivation, was prolonged in rhTNF-treated cells when compared to that of control cells. We conclude that immune peptides such as rhTNF can alter cellular functions of sympathetic neurons via modulating ionic conductances. However, these changes observed in calcium currents of SCG neurons cannot account for the effect of rhTNF on norepinephrine secretion observed in a previous study. It is proposed that rhTNF exerts an additional effect at a later event in the exocytotic process.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1992

Improved detection of HIV-2 DNA in clinical samples using a nested primer-based polymerase chain reaction.

A two-step polymerase chain reaction (PCR), with four double (nested) primer pairs, used for the detection of HIV-2 in clinical samples is described. With these four nested primer pairs we could detect HIV-2 DNA in 17 of 17 virus isolates and in blood mononuclear cell samples from 31 of 37 (83.7%) seropositive individuals after ethidium bromide staining of the amplified DNA. The nested primer PCR was also compared with a single primer pair-based PCR followed by hybridization. The sensitivities of the two methods were almost equal, but the nested primer PCR offered obvious technical advantages.

Adolescent↗

PubMed1991

Prevention of HIV-2 and SIVsm infection by passive immunization in cynomolgus monkeys.

Infection of macaques with simian immunodeficiency virus (SIV) and human immunodeficiency virus type 2 (HIV-2) are useful models for studies of immunotherapy and vaccination against HIV as well as for testing of antiviral drugs. Vaccine research showing protective immunity in immunized monkeys has indicated that it will be possible to develop a vaccine for prevention of human HIV infection, although many hurdles remain. The design of an HIV vaccine would be helped if the basis of the protective immunity could be elucidated. Passive immune prophylaxis offers a means to determine the relative role of antibodies in protection against infection. We have studied whether a transfer of antibodies can prevent HIV-2 and SIVsm (SIV of sooty mangabey origin) infection in cynomolgus monkeys. Sera with high antibody titres were collected, heat-treated and injected into naive animals 6 h before challenge with 10-100 monkey-infectious doses of live homologous virus. All control animals treated with normal monkey serum (n = 6) or no serum (n = 39) became infected by the challenge virus, whereas five out of seven animals pretreated with antibody-containing serum at a dose of 9 ml kg-1 resisted infection. Thus passively transferred antibodies can protect against a low-dose lentivirus challenge in a nonhuman primate.

Animals↗

PubMed1991

Hemolysis due to branch pulmonary stenosis after the arterial switch procedure.

An infant with d-transposition of the great arteries underwent arterial switch operation using the modified Jatene technique. Severe bilateral branch pulmonary artery stenosis and mechanical hemolysis subsequently developed. The hemolysis resolved after surgical repair of the stenotic arteries. Probable causes are discussed.

Anemia, Hemolytic↗

PubMed1991

Isolate-specific neutralizing antibodies in patients with progressive HIV-1-related disease.

Four individuals with increasing severity of HIV-1 infection were studied for serum neutralizing activity against their own virus isolates collected during 1-3 years. Sequential serum samples and HIV-1 isolates were available from these patients from the stage of lymphadenopathy to severe immunodeficiency. The replicative capacity of isolates changed from slow/low to rapid/high in each patient during the study period. Sequential virus isolates showed differences in sensitivity to neutralization by autologous as well heterologous area. Taken together with our previous results demonstrating that variant viruses resistant to neutralization by autologous sera emerge during the year following primary infection, neutralization-resistant variants seem to emerge during the entire course of HIV-1 infection. The ability to produce neutralizing antibodies to autologous virus appears to correlate with replicative capacity of the virus and the degree of immunodeficiency in the patient.

Acquired Immunodeficiency Syndrome↗

PubMed1991

Brain-derived cells can be infected with HIV isolates derived from both blood and brain.

HIV type 1 and 2 isolates derived from brain and blood of infected individuals were used to infect astrocytic cells of tumor origin. Infection was monitored by polymerase chain reaction. The majority of the isolates infected the glioma cells, independently of the source of isolation. Added to the fact that the majority of primary HIV isolates infect cells of the monocyte/macrophage lineage, these results indicate that primary blood and brain HIV strains have similar target cells. The production of virus from infected astrocytes was detected only upon infection with two macrophage-adapted strains. Also in this case, the number of infected cells was very low and only one in 5000 cells carried the proviral HIV genome.

Blood↗

PubMed1991

Vaccine protection against HIV-2 infection in cynomolgus monkeys.

The aim of this study was to determine if protection against an infectious human immunodeficiency virus type 2 (HIV-2) challenge could be obtained in cynomolgus macaques by active immunization using whole killed virus vaccine. Four monkeys were immunized with killed HIV-2SBL-6669, two of them with five intramuscular (im) injections of viral preparation containing 100 or 300 micrograms protein emulsified in incomplete Freund's adjuvant (IFA) and the two remaining received four im injections of 25-50 micrograms viral protein in iscoms. Each of the four vaccinated cynomolgus monkeys, along with four unvaccinated controls, were challenged intravenously two weeks after the last booster with approximately 100 animal infectious doses (ID50) of live HIV-2SBL-6669. All four immunized monkeys developed antibodies to HIV-2 envelope and core proteins before challenge exposure to HIV-2, but only the two animals vaccinated with virus in IFA developed detectable neutralizing antibodies. The two monkeys immunized with killed virus in IFA have shown no evidence of infection nine months after challenge with live virus. When blood and lymph node cells from these animals were transfused into naive cynomolgus monkeys, the recipients remained free of infection. In contrast, virus was recovered repeatedly in all nonimmunized animals and in the two animals immunized with iscom-associated viral antigens, which had a low content of envelope gp125 antigen. The demonstration of vaccine-induced protection against HIV-2 in a nonhuman primate raises hope for effective immunization against HIV infections in humans as well.

Animals↗