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Biomedical subjects

P Grob

Publications and source records attributed to P Grob.

At least 37 records · Page 2Linked to original sources
PubMed1998

A system for stable indirect immobilization of multimeric recombinant proteins.

BACKGROUND: To perform an ELISA or for panning phage particles which display recombinant proteins, one of the reactants is immobilized on solid phase. Immobilization in ELISA is generally performed by passive adsorption of ligands to plastic. However, protein is denatured during the adsorption process. This may result in low efficiency interaction between ligands and receptors which depend on native structures. In contrast, indirect immobilization has been shown to prevent protein denaturation. OBJECTIVES: The aim was to develop a system that allows efficient and stable indirect immobilization of a variety of recombinant multimeric proteins to solid phase. RESULTS: A new vector was constructed which allows the expression of up to three proteins linked by the Jun/Fos leucine zipper. Purification of the resulting protein was achieved by Ni+ affinity chromatography utilizing the 6xHis-ABP (albumin binding protein) protein fused to the N-terminus of the Jun polypeptide. The high binding affinity of ABP to rat serum albumin (RSA) was exploited for indirect immobilization of recombinant proteins to solid phase. In an enzyme linked assay, the binding of ABP to immobilized RSA was shown to be 10-1000 times more efficient than other immobilization systems. Using the ZZ IgG binding domain of staphylococcal protein A as bait, the RSA-ABP immobilization system was successfully used to screen and enrich IgG Fc encoding DNA fragments from a cDNA phage library. CONCLUSION: The newly designed vector termed pJuFoexpress allows production and purification of multimeric protein complexes linked by the Jun/Fos leucine zipper. Without chemical modifications, the recombinant proteins can be immobilized indirectly to solid phase. The immobilization results in the stable display of native, biologically active proteins which can be used in ELISA and phage display systems.

Animals↗
PubMed1998

Improvement in immune function due to treatment with indinavir despite severe immune deficiency.

To study the virological, immunological and clinical effects of the protease inhibitor indinavir in human immunodeficiency virus (HIV)-infected patients with CD4 counts < 50 cells/mm3, indinavir was added to prior treatment with nucleoside analogues in a prospective open-label study in 23 HIV-infected patients with median CD4 count of 10 cells/mm3 and median serum HIV-1 RNA load of 27,508 copies/ml. Addition of indinavir induced a decrease in HIV-1 RNA levels to < 400 copies/ml in 15 patients that was maintained until week 36 of the study in 8 (35%) patients. The median increase in CD4 cell counts was 92 cells/mm3 (range 55-258 cells/mm3) and in CD8 counts was 245 cells/mm3 (range 51-1552 cells/mm3) at week 30. The treatment induced a significant CD8 T cell expansion, consisting in the first 6 weeks of predominantly memory CD45RO+ cells and followed by expansion of naive cells from week 12 on, and a significant decrease in the proportion of activated CD8/CD38 cells. In addition, significant increases in T cell proliferation following stimulation with phytohaemagglutinin and significant decreases in the rates of spontaneous apoptosis of CD4+ and CD8+ T cells were observed. In conclusion, the addition of indinavir induced restoration of both memory and naive CD8 T cells. Corresponding evidence of improving T cell function, as assessed by enhanced lymphoproliferative capacity and diminished propensity to undergo apoptosis, provides evidence for treatment-induced regeneration of immune function even in patients with severe immunodeficiency.

Adult↗
PubMed1997

Combined hormono/chemotherapy as primary treatment for metastatic prostate cancer: a randomized, multicenter study of orchiectomy alone versus orchiectomy plus estramustine phosphate. The Dutch Estracyt Study Group.

OBJECTIVES: Based on the theory that hormone-resistant cells are present in all metastatic patients, early administration of chemotherapy appears to be logical and its use is supported by experimental studies. Therefore, trials with combined hormonal and cytotoxic treatment as primary therapy should be conducted. In the present trial, the efficacy and tolerance of estramustine phosphate (EMP) as a chemotherapeutic agent in addition to hormonal treatment (orchiectomy) was studied in patients with metastatic and nonmetastatic prostate cancer not previously treated. EMP was chosen because it produces few serious adverse reactions and no cumulative toxicity. METHODS: Four hundred nineteen patients were included in a 1.5-year period starting in January 1989. Patients with locally advanced prostate cancer or with bone metastases were randomized to orchiectomy (O) or orchiectomy followed by EMP (O + E), given until progression. RESULTS: Analysis of the total group showed no significant difference in time to progression between the treatment groups. Because the course of the disease is different in patients with either T4 tumor only or with lymph node metastases only (M0) as compared with patients with bone metastases (M1) and because the number of progressions in the M0 patients was low, corresponding analyses were performed for these subgroups as well. In the M1 patients, there was a tendency for a longer time to progression in the O + E group than in the O group, but there was no indication of a difference between the groups with regard to survival. In the M0 patients, there was no indication of any difference in results between the treatments. Multivariate analysis of prognostic factors showed pain, alkaline phosphatase, metastasis status, and tumor stage to be significant factors. There was a relation between age and drug treatment in that a significant beneficial effect of EMP in terms of prolonged progression-free interval as well as survival was evident in younger patients (aged less than 73 years) with metastatic disease. Tumor stage was also of importance for the drug effect; T0 to T3 patients who received EMP survived longer than those who were treated with orchiectomy only. The most common adverse reaction was nausea in the O + E group, which led to discontinuation of the drug in 7 patients. Cardiovascular problems are not uncommon in this age group, and there was a higher incidence of cardiovascular events, predominantly cardiac failure, in the O + E group, leading to treatment interruption in 16 patients. CONCLUSIONS: Our results indicate that future studies of hormono/chemotherapy should focus on younger patients with bone metastases.

Aged↗
PubMed1997

Mutational characterization of promoter regions recognized by the Salmonella dublin virulence plasmid regulatory protein SpvR.

The virulence plasmid-encoded spv regulon is essential for virulence of Salmonella dublin in mice. The spvR gene product belongs to the LysR family of transcriptional regulator proteins. SpvR induces the expression of the spvABCD operon and positively regulates its own expression. DNase I protection analysis with purified SpvR fusion proteins identified SpvR binding sites within the spvA and spvR promoters (P. Grob and D. G. Guiney, J. Bacteriol. 178:1813-1820, 1996). We have used PCR mutagenesis, combined with functional selection for reduced SpvR affinity, to define the DNA elements essential for SpvR binding. For the spvR promoter fragment, a screen for reduced expression was also applied. Sequence analysis of the resulting mutant fragments reveals that the base pair changes are clustered in distinct regions. Determination of the apparent dissociation constants of SpvR for the mutant promoters showed that the spvA LysR-type motif and the upstream palindromic sequences of both promoters play an important role in SpvR recognition.

Animals↗
PubMed1996

In vitro binding of the Salmonella dublin virulence plasmid regulatory protein SpvR to the promoter regions of spvA and spvR.

The spv regulon of Salmonella dublin is essential for virulence in mice. SpvR, a LysR-type regulator, induces the expression of the spvABCD operon and its own expression in the stationary phase of bacterial growth and in macrophages. We constructed fusion proteins to the maltose-binding protein (MBP) and a His tag peptide (His) to overcome the insolubility and to facilitate purification of SpvR. We demonstrated that both fusion proteins, MBP-SpvR and His-SpvR, were able to induce spvA expression in vivo. MBP-SpvR was produced as soluble protein, whereas His-SpvR was only marginally present in the soluble cell fraction. Affinity chromatography resulted in at least 95% pure MBP-SpvR protein and in an enrichment of His-SpvR. Gel mobility shift assay revealed that the SpvR fusion proteins were able to bind to 125-and 147-bp DNA fragments of the spvA and spvR promoter regions, respectively. DNase I footprint experiments showed that the fusion proteins protected DNA regions of 54 and 50 bp within the spvA and spvR promoter regions, respectively.

Bacterial Proteins↗
PubMed1995

The European Public Health Association.

The European Public Health Association (EUPHA) was founded in 1992 and represents 11 European countries. Its goals include encouraging collaboration in furthering European public health through research, education and action based on sound scientific grounds. It provides an opportunity for those interested in public health to meet and exchange information, both through an annual conference and a quarterly scientific journal. EUPHA is delighted to be represented on the Viral Hepatitis Prevention Board and supports the aims of the Congress.

Europe↗
PubMed1995

Introduction to epidemiology and risk of hepatitis B.

The most important modes of transmission of hepatitis B virus (HBV) are sexual, needle stick (both accidental or through intravenous drug use), blood transfusion or from mothers to newborns. The outcome of HBV infection mainly depends on the immune response of the host but is also influenced by the capability of the virus to escape defence mechanisms by integration into the genome of the host's hepatocytes. These factors affect whether HBV infection leads to acute hepatitis or remains asymptomatic, whether the infection resolves to immunity or becomes chronic and whether chronic clinical sequellae such as chronic hepatitis, liver cirrhosis or hepatocellular carcinoma develop. The epidemiological status of a given country with regard to HBV depends on socioeconomic factors, the proportion of individuals with risky life styles, the pre-existing prevalence of HBV, the vaccine programme available and compliance to hygienic measures.

Hepatitis B↗
PubMed1995

The influence of leukocyte filtration during cardiopulmonary bypass on postoperative lung function. A clinical study.

The accumulation of activated leukocytes in the pulmonary circulation plays an important role in the pathogenesis of lung dysfunction associated with cardiopulmonary bypass. Animal studies have demonstrated that the elimination of leukocytes from the circulation reduces postoperative lung injury and improves postoperative pulmonary function. We conducted a prospective randomized clinical study to evaluate whether postoperative lung function could be improved by use of a leukocyte filter during cardiopulmonary bypass. Elective coronary artery bypass grafting was done with a leukocyte-depleting arterial blood filter incorporated in the extracorporeal circuit (14 patients, leukocyte filter group) or without the filter (18 patients, control group). Blood samples collected at intervals before, during, and after operation were used for analysis of blood cell counts, elastase concentrations, and arterial blood gases. The use of the leukocyte filter caused no significant reduction in leukocyte count (p = 0.86). There were no differences in postoperative lung function between the groups, as assessed through (1) oxygenation index (290 for leukocyte filter group compared with 329 for control group, 95% confidence interval, 286 to 372, p = 0.21), (2) pulmonary vascular resistance (p = 0.10), and (3) intubation time (16.6 hours for leukocyte filter group versus 15.7 hours for control group, 95% confidence interval, 12.1 to 19.1 hours, p = 0.72). The levels of neutrophil elastase were significantly higher at the end of cardiopulmonary bypass in the leukocyte filter group (460 microgram/L in leukocyte filter group versus 230 microgram/L in control group, 95% confidence interval, 101 to 359 microgram/L, p = 0.003). We conclude that the clinical use of the present form of leukocyte-depleting filter did not improve any of the postoperative lung function parameters analyzed in this study.

Cardiopulmonary Bypass↗
PubMed1995

Intrathecal and serum interleukin-6 and the acute-phase response in patients with severe traumatic brain injuries.

Patients with severe traumatic brain injury (TBI) show a profound acute-phase response. Because interleukin-6 (IL-6) is an important mediator of these pathophysiological changes, IL-6 levels were monitored in the cerebrospinal fluid (CSF) and serum of 20 patients with severe isolated TBI. All patients received indwelling ventricular catheters for intracranial pressure monitoring and for release of CSF when intracranial pressure exceeded 15 mmHg. CSF and blood samples were drawn daily for up to 14 days. The CSF/serum albumin ratio (QA) served as a parameter of blood brain barrier dysfunction. Differential blood counts as well as the acute-phase proteins C-reactive protein, alpha 1-antitrypsin, and fibrinogen were recorded. IL-6 was detected in all CSF samples and reached values of up to 31,000 pg/mL, while serum levels remained significantly lower (alpha < or = .01) and never exceeded 1,100 pg/mL the entire study period. A correlation between CSF and serum IL-6 was found initially after the trauma and corresponded to a severe dysfunction of the blood brain barrier (r = .637, p = .001). Maximum IL-6 concentrations in serum correlated with peak levels of acute-phase proteins (C-reactive protein, alpha 1-antitrypsin, and fibrinogen). With regard to blood cell count, an initial leukocytosis combined with a borderline lymphocytopenia was observed. Thrombocytes decreased to a subnormal level during the first few days, but reached supranormal numbers by the end of the study period. Our results show that the increase of IL-6 levels in CSF and serum is followed by a profound acute-phase response in patients with TBI. Because cytokine concentrations are significantly lower in serum compared with CSF, we hypothesize that IL-6 produced in the central nervous system may play a role in initiating the acute-phase response.

Acute-Phase Proteins↗
PubMed1994

A phase I/IIA clinical study with a chimeric mouse-human monoclonal antibody to the V3 loop of human immunodeficiency virus type 1 gp120.

A phase I/IIA clinical trial with the chimeric mouse-human monoclonal antibody CGP 47,439 to the principal neutralization determinant in the V3 region of human immunodeficiency virus type 1 (HIV-1) strain IIIB envelope protein gp120 is reported. The trial was an uncontrolled single-center, open-label, multidose tolerability, immunogenicity, and pharmacokinetic study in homosexual men with advanced HIV disease. Patient groups were formed on the basis of the reactivity of the antibody with the gp120 of their HIV-1 isolates. Intravenous infusions of 1, 10, and 25 mg of antibody were followed by seven escalated doses of 50, 100, and 200 mg, every 3 weeks. The antibody was well tolerated; no toxicity was observed. Some patients showed a transient but insignificant antibody response to the antibody with no apparent adverse reactions or accelerated elimination of it. Substantial serum levels of the antibody were maintained with a mean t1/2 beta of 8-16 days. A virus burden reduction was observed in some patients.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Effect of patient characteristics and disease manifestations on the outcome of acute otitis media at 2 months.

BACKGROUND: Optimal therapy for acute otitis media (AOM) is controversial and there is no consensus regarding which antibiotic to use, how long to administer it, or whether antibiotics are effective at all. Knowledge of the effects of patient characteristics and disease manifestations is needed to individualize treatment and to evaluate large-scale trials. METHODS: Data originated from 2251 patients with AOM, aged newborn to 15 years, who participated in a prospective primary care study in eight countries. At the initial visit, medical history, symptoms, physical findings, and treatment data were recorded. Follow-up 2 months later identified changes in treatment and outcome. RESULTS: Patients younger than 13 months were less likely to have recovered than those aged 13 months to 15 years (P = .05). Using univariate analysis for infants aged 12 months or younger, male sex, prior episodes of AOM, and serous otitis media were associated with poor outcome. For older patients, poor outcome was associated with initial history of ear tubes, prophylactic antibiotic use, ear discharge, decreased hearing, serous otitis media; and past episodes of AOM; the symptom of decreased hearing; and the finding of pus exuding from the tympanic membrane. Using multivariate analysis for infants aged 12 months or younger, a history of serous otitis media (odds ratio [OR], 2.3; 95% confidence interval [CI], 0.95-5.7), past episodes of AOM (OR, 1.9; 95% CI, 0.82-4.5), and male sex (OR, 1.7; 95% CI, 1.0-3.0) made independent contributions to poor outcome. For children aged 13 months to 15 years, significant variables included pus drainage (OR, 2.2; 95% CI, 1.5-3.3), a history of ear tubes (OR, 2.3; 95% CI, 1.5-3.6), past episodes of AOM (OR, 1.8; 95% CI, 1.3-2.34), and a history of serous otitis media (OR, 1.4; 95% CI, 1.0-1.9). CONCLUSIONS: Patient characteristics and disease manifestations are significant determinants of AOM outcome.

Acute Disease↗
PubMed1993

A novel response-regulator is able to suppress the nodulation defect of a Bradyrhizobium japonicum nodW mutant.

The two-component regulatory system Nod-VW of Bradyrhizobium japonicum is essential for the nodulation of the legume host plants Vigna radiata, V. unguiculata and Macroptilium atropurpureum. The NodV protein shares homology with the sensor-kinases, whereas the NodW protein is a member of the response-regulator class. We report here the identification of a new B. japonicum DNA region that is able to suppress the phenotypic defect of a nodW mutant, provided that this region is expressed from a foreign promoter. The minimal complementing region, which itself is not essential for nodulation in a nodW+ background, consists of one gene designated nwsB (nodW-suppressor). The deduced amino acid sequence of the nwsB gene product shows a high degree of homology to NodW. The nws B gene is preceded by a long open reading frame, nwsA, whose putative product appears to be a sensor-kinase. Downstream of nwsB, an open reading frame encoding a second putative response-regulator was identified. Interspecies hybridization revealed the presence of nwsAB-like DNA also in other Bradyrhizobium strains. Using nwsB'-'lacZ fusions, the nwsB gene was found to be expressed rather weakly in B. japonicum. This low level of expression is obviously not sufficient to compensate for a nodW- defect, whereas strong overexpression of nwsB is a condition that leads to suppression of the nodW- mutation.

Amino Acid Sequence↗
PubMed1993

Nevirapine synergistically inhibits HIV-1 replication in combination with zidovudine, interferon or CD4 immunoadhesin.

OBJECTIVE: To determine whether synergistic inhibition of HIV-1 replication would result from the in vitro use of nevirapine in combination with zidovudine, interferon (IFN)-alpha 2C, and CD4 immunoadhesin. DESIGN AND METHODS: The non-nucleoside reverse transcriptase inhibitor nevirapine (formerly BI-RG-587) was tested in combination with the other antiretrovial agents. Assays were performed on stimulated peripheral blood lymphocytes infected with HIV-1. Virus replication was assessed by the release of viral p24 antigen into culture supernatants. The median-effect principle was used to assess for synergistic interactions of the combined agents. RESULTS: Zidovudine, IFN-alpha 2C and CD4 immunoadhesin, when used in combination with nevirapine, synergistically inhibited HIV-1 replication in human peripheral blood lymphocytes compared with each agent used alone. Some analyses were also consistent with additive effects, but antagonism was not noted. CONCLUSION: These in vitro findings provide a scientific basis for future trials with similar drug combinations.

Antiviral Agents↗
PubMed1993

Prevalence of markers of hepatitis viruses A, B, C and of HIV in healthy individuals and patients of a Cambodian province.

So far little was known on the epidemiology of hepatitis A, B, C and of AIDS in Cambodia and especially not in the rural area of Takeo. Therefore serological markers for past or ongoing infections with the disease causing viruses were measured in 559 healthy individuals (305 adults, 200 children and 54 mothers of children with liver disorders) and in 185 individuals (103 adults and 82 children) with liver or kidney diseases. In none of the 744 samples tested was anti-HIV detected. 10-37% of the children and 73% of the adults showed HBV-markers, HBsAg being detectable in 2-14% of the children and in 8% of the adults. The prevalence for anti-HCV was 6.5% in the adults with a predilection in males (9%). No markers for HCV infections were found in children. Growing, age related proportions of children (27-97%) and 100% of the adults were anti-HAV IgG positive. HBsAg was detected in 46% of the adults with acute hepatitis, in 45% of those with chronic hepatitis/liver cirrhosis and in 90% of patients with hepato-cellular carcinoma (HCC). In children the corresponding figures were 18% for acute hepatitis and 18% for chronic hepatitis. Patients with acute hepatitis or HCC had a similar prevalence of anti-HCV as healthy individuals. However, 34% of the adult patients with chronic hepatitis/cirrhosis showed signs of a HCV-infection. When the data were analysed with respect to modes of viral transmission, crowding, transmission by unsafe sexual practice or contaminated injection material, and to a lesser extent vertical transmission, seem to be relevant for HBV. The main mode of acquiring HCV infection is probably through medical injections of all sorts, a habit which is very popular in Takeo. Prophylactic measures should concentrate on the prevention of HBV and HCV infections by hygienic means. HBV mass vaccination should be considered in the future.

Adolescent↗