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Biomedical subjects

A Jansen

Publications and source records attributed to A Jansen.

At least 55 records · Page 3Linked to original sources
PubMed2000

Trans-complementation of vector replication versus Coxsackie-adenovirus-receptor overexpression to improve transgene expression in poorly permissive cancer cells.

Gene therapy of cancer requires high-level expression of therapeutic transgenes in the target cells. Poor gene transfer is an important limitation to adenovector-mediated cancer gene therapy. We investigated two fundamentally different approaches to improve transgene expression in poorly permissive cancer cells. First, overexpression of the adenovirus attachment receptor CAR to facilitate receptor-mediated adenovector (AdV) uptake into the target cells; second, co-infection of this vector together with traces of replication competent adenovirus (RCA) accidentally arising by back-recombination during large-scale vector preparation. Among eight gastrointestinal cancer cell lines, the colorectal cancer lines showed particularly poor vector-mediated transgene expression (down to 67-fold lower than in HeLa cells). Expression of the adenovirus receptors CAR, alpha(v)beta5- and alpha(v)beta3-integrin were highly variable between cell lines. AdV uptake was significantly associated with CAR levels on the cell surface, but not with those of the integrins. AdV-mediated CAR overexpression increased CAR density on the surface of all investigated tumor cells and led to enhancement of transgene expression by 1.8- to 6.7-fold. The other principle to enhance transgene expression was 'trans-complementation' of the therapeutic vector, ie induction of its replication within the target cells. Traces of RCA in a vector preparation, as well as purified RCA were found to provide sufficient E1-region transcripts to induce replication of the therapeutic vector genome. The number of adenovector-based transgene expression cassettes was greatly amplified by this principle, notably without any influence on the rate of vector entry. Co-infection of four colorectal cancer cell lines with marker vector plus RCA (at around 240:1 particle ratio) resulted in far stronger enhancement of transgene expression (up to 46-fold) as compared with CAR overexpression, even in cancers almost refractory to standard adenovector-mediated gene transfer. Whereas RCAs need to be strictly avoided in gene therapy of non-malignant diseases for safety reasons, the magnitude of helper virus-induced therapeutic transgene expression could possibly warrant application of this principle to overcome the resistance of highly malignant cancers against gene therapy.

Adenoviridae↗
PubMed2000

Choroidal calcifications in patients with Gitelman's syndrome.

Gitelman's syndrome is a renal tubular disorder characterized by a sodium and chloride reabsorption defect in distal tubular cells that determines hypokalemia, metabolic alkalosis, hypomagnesemia, and low calcium excretion. The presence of choroidal calcifications was sought in five patients with Gitelman's syndrome by ophthalmic examination, fluorescein angiography, indocyanine green angiography, and ocular ultrasonography. Calcifications observed in the choroid of two patients were shown by ultrasonography in both patients. Ophthalmic and fluorangiographic examinations detected this alteration in one of the two subjects. Chondrocalcinosis was found in one patient with choroidal calcifications. These findings suggest that precipitation of calcium salts can occur in the choroidal tissue of patients with Gitelman's syndrome. Deposits appeared to be well seen by ultrasonography because of their depth in ocular tissues. Sclerochoroidal calcifications may be favored by the low calcium excretion, which is associated with normal intestinal calcium absorption in patients with Gitelman's syndrome.

Adolescent↗
PubMed2000

Comparison of efficiencies of three techniques for colon surgery.

PURPOSE: To determine the most efficient technique for performing a colectomy, we used the methodology of time-motion analysis. METHODS: The efficiency of five hand-assisted and six regular laparoscopic colectomies and one open colectomy, performed by four surgeons in three different hospitals, was measured. The open colectomy was analyzed as a reference procedure. RESULTS AND CONCLUSIONS: The hand-assisted laparoscopic technique was the most efficient. Hand-assisted laparoscopy was therefore less time consuming than laparoscopic surgery. Open surgery was the fastest technique, because the time for every surgical motion is a factor of three shorter than for the two laparoscopic techniques.

Colectomy↗
PubMed2000

Selective cognitive processing of drug cues in heroin dependence.

Previous studies provide evidence for the selective processing of disorder related stimuli on anxiety, depression, and eating disorders. There exist some preliminary indications that selective processing of drug cues may be involved in drug craving and relapse that deserve further investigation. In order to investigate the role of processing bias in an abnormal motivational system, the attentional bias for drug related stimuli was studied in a heroin dependent population. Heroin dependent participants (n = 21) and control participants (n = 30) performed a supra- and subliminal heroin Stroop task and heroin craving was assessed. Heroin dependent participants showed a considerable attentional bias for supraliminally presented heroin cues. However, there was no evidence for a preattentive bias on the subliminal presented cues. Reaction time on heroin cues was significantly predicted by heroin craving-levels. Results indicate that selective processing may be related to motivational induced states in general. The finding are discussed in the context of selective information processing in general psychopathology and in motivational processes as addiction specifically.

Adult↗
PubMed1999

An experimental test of the relationship between self-esteem and concern about body shape and weight in restrained eaters.

OBJECTIVE: Although self-esteem and overconcern with body shape and weight are considered to be closely connected in bulimia nervosa, little empirical research has been done to investigate the alleged link. METHOD: In this study, we examined experimentally whether overconcern with body shape and weight was connected with self-esteem in an analogue sample of high restrained eaters by means of a subliminal lexical decision task. RESULTS: It could indeed be demonstrated that low self-esteem and overconcern with body shape and weight are associated in high restrained eaters: after priming low self-esteem, the accessibility of subliminally presented body shape and weight stimuli was increased. The effect was not found with a supraliminal lexical decision task. DISCUSSION: Apparently, the automatic, nonconscious processing of body shape and weight words was influenced in high restrained eaters with a low state self-esteem, whereas the strategic, conscious processing was not. As soon as the body shape and weight stimuli were processed consciously, the initial increased accessibility was countered and the effect disappeared.

Adult↗
PubMed1999

Recording of swallowing events using electromyography as a non-invasive measurement of salivation.

The present study examined whether the measurement of swallowing activity by electromyography (EMG) provides a sensitive and valid method for the assessment of the amount of saliva secreted. Thirteen subjects tasted lemon juice and water, and smelled lasagna and hay, while the amount of saliva, measured with the aid of cotton dental rolls, was compared with the number of peaks in the EMG activity of the musculus digastricus. Swallowing indeed differentiated between the stimuli and the correlation between the number of swallows and the amount of saliva was significant. The present data suggest that monitoring the swallowing movement using EMG might be a sensitive, valid and reliable method for the measurement of salivary flow. The use is recommended for the measurement of salivation when a simple and non-invasive method is needed.

Adult↗
PubMed1999

Axial length in patients with diabetes.

PURPOSE: To investigate the relationship between axial length and retinal involvement in patients with diabetes. METHODS: A total of 157 consecutive patients with diabetes underwent biometry. The patients were divided into three groups, according to retinopathy: 44 without retinopathy, 37 with background retinopathy, and 76 with proliferative retinopathy. To compare axial length in diabetic versus nondiabetic subjects, a control group of 157 healthy subjects with age and sex distribution similar to the diabetic group was selected from an orthopedic clinic. We investigated in the diabetic group whether the axial length was related to specific type of diabetes (non-insulin-dependent or insulin-dependent), duration of disease, presence of retinopathy, or laser treatment. To eliminate the confounding effect of myopia, we excluded all patients with axial length greater than 24 mm from the two groups. Comparison of diabetic patients without retinopathy versus nondiabetic subjects was also performed. RESULTS: Diabetic patients presented shorter axial lengths compared with the controls (mean +/- standard deviation, 22.4+/-1.3 mm versus 23.4+/-1.3 mm; P<0.001). Significantly shorter axial lengths were found in the background and proliferative retinopathy groups compared with the group without retinopathy (22.0+/-1.2 mm and 22.1+/-1.1 mm versus 23.2+/-1.4 mm, respectively; P<0.05). No difference in axial length was found between the diabetic patients without retinopathy and the nondiabetic subjects (P = 0.3). Multivariate analyses showed that retinopathy was negatively correlated with axial length (P<0.01). Including only the patients with axial length under 24 mm, we obtained similar results. CONCLUSION: Axial length is shorter in diabetic patients than in nondiabetic subjects. Within the diabetic group, patients with retinopathy had shorter axial lengths than did patients without retinopathy.

Anthropometry↗
PubMed1999

Whole blood capcellia CD4/CD8 immunoassay for enumeration of CD4+ and CD8+ peripheral T lymphocytes.

We evaluated the Whole Blood Capcellia(R) CD4/CD8, an immunoenzymatic method that provides absolute counts of CD4+ and CD8+ T cells in peripheral blood. The assay is based on the separation of T cells by use of an anti-CD2 magnetic bead suspension, followed by reaction of the CD4 or CD8 molecules with the corresponding monoclonal antibody coupled to peroxidase. CD4-positive monocytes were excluded from the assay. Freeze-dried magnetic bead-T-cell complexes were used as calibrators. Capcellia counts from HIV-1-infected patients were compared with those obtained by flow cytometry as the comparison method. The results by Capcellia correlated well with those by flow cytometric analysis: r2 = 0.95; P <0.001; (y = 0.96x - 22.1); Sy|x = 64 for CD4; r2 = 0.81; P <0.001; (y = 1.26x - 76.4); Sy|x = 139 for CD8; n = 76. The correlation between CD4+ T-cell counts determined by two trained experimenters was significant (r2 = 0.96). Our results indicate that this new ELISA technique for lymphocyte immunophenotyping is an efficient alternative to flow cytometry.

Antibodies, Monoclonal↗
PubMed1998

Expression of functional P2-purinergic receptors in primary cultures of human colorectal carcinoma cells.

Primary cell cultures of human colorectal carcinomas were established and characterized immunocytochemically. In the isolated cancer cells intracellular Ca2+ concentrations ([Ca2+]i) were measured by the fura-2 method. Stimulation with either extracellular ATP or UTP caused a biphasic rise of [Ca2+]i in a dose-dependent manner and cross-desensitization between both nucleotides was observed. The rank order of potency was ATP >== UTP > ATP-gamma-S > ADP > adenosine which is characteristic for a P2U-receptor subtype. Selective agonists of P1-, or P2X- purinoceptors had no effect on [Ca2+]i. The initial rise in [Ca2+]i was independent of extracellular calcium [Ca2+]e, whereas the second phase was not observed under [Ca2+]e-free conditions suggesting a capacitative Ca2+-entry-mechanism. Intracellular Ca2+ mobilization was proven by use of the Ca2+-ATPase inhibitor thapsigargin. P2U-specific mRNA could be detected by RT-PCR in both colorectal tumor tissues and in the human colorectal cancer cell line HT 29. In HT 29 cells, the hydrolysis-resistant ATP analog ATP-gamma-S inhibited cell proliferation and, also, induced apoptosis in a dose-dependent manner. Thus, human colorectal cancer cells express functional P2U-receptors which may play a role in the regulation of cell proliferation and apoptosis.

Adenosine Triphosphate↗
PubMed1998

Expression of functional GABAA receptors in cholecystokinin-secreting gut neuroendocrine murine STC-1 cells.

1. Gastrointestinal neuroendocrine (NE) cells synthesize, store and secrete gamma-aminobutyric acid (GABA). Recently, an autocrine-paracrine function of GABA has been proposed for secretion from NE cells. 2. To search for functional GABAA receptors in NE gut cells, we performed whole-cell and perforated-patch-clamp studies in the intestinal cholecystokinin (CCK)-secreting NE cell line STC-1. 3. Application of GABA evoked currents in STC-1 cells. These effects were mimicked by muscimol, an agonist of GABAA receptors, and blocked by picrotoxin or bicuculline, antagonists of GABAA receptors. The GABA- or muscimol-activated currents reversed near 0 mV, which under the recording conditions used was consistent with the activation of the GABAA receptor-Cl- channel complex. 4. In contrast to the effect on most neurons, GABA as well as muscimol led to a (reversible) depolarization of the membrane potential of STC-1 cells. Membrane depolarization in turn activated voltage-gated Ca2+ channels and increased intracellular Ca2+ concentrations in STC-1 cells. 5. In accordance with the observed membrane depolarization and activation of voltage-gated Ca2+ channels, both GABA and muscimol stimulated Ca2+-dependent CCK release. In contrast, bicuculline inhibited the GABA-induced secretion of CCK. 6. Using the reverse transcription-polymerase chain reaction (RT-PCR), mRNA of the GABAA receptor subunits alpha2, alpha3, alpha5, beta1, beta3 and delta could be detected in STC-1 cells. 7. In summary, we have shown that the CCK-secreting gut NE cell line STC-1 expresses functional GABAA receptors and that GABA stimulates CCK release. Thus, GABA is involved in the fine tuning of CCK secretion from the gut NE cell line STC-1.

Animals↗
PubMed1998

No evidence for a selective processing of subliminally presented body words in restrained eaters.

OBJECTIVE: In the present study, it was hypothesized that restrained eating subjects will show an attentional bias for body shape and weight words during the automatic stage of information processing and not during the strategic or controlled stage. METHOD: Thirteen high restrained and fifteen low restrained eaters participated in the experiment. Body shape and weight words as well as neutral words were presented both supraliminally and subliminally during a computerized Stroop task. RESULTS: The high restrained eaters did not show distortions in the processing of body shape and weight stimuli; neither an early automatic processing priority nor a pattern of strategic processing selectivity characterizes restrained eaters. DISCUSSION: The absence of cognitive distortions in the processing of body shape and weight information might point to a qualitative difference between normal restrained eaters and subjects with eating disorders of clinical severity.

Adult↗
PubMed1998

The adipocyte fatty acid-binding protein locus: characterization and association with intramuscular fat content in pigs.

The porcine A-FABP gene (FABP4) was isolated and sequenced to study the role of A-FABP in the differentiation of intramuscular fat (IMF) accretion in pigs. The coding sequence of the porcine A-FABP gene is highly conserved across human, mouse, and rat. Moreover, all the functionally important amino acids are conserved. This high similarity extends into the first 270 bp of the 5' upstream region. Within this region, a 56-bp nucleotide sequence was completely identical with the corresponding sequence in the mouse A-FABP gene, which contains the transcription factor binding sites for C/EBP and AP-1, and is implicated in the differentiation-dependent regulation of A-FABP. The A-FABP gene was assigned to porcine Chromosome (Chr) 4 by a porcine sequence-specific PCR on a cell hybrid panel, fully consistent with comparative mapping data with human and mouse. In the first intron of the porcine A-FABP gene, a microsatellite sequence was detected that was polymorphic for all six pig breeds tested. This genetic variation within the A-FABP gene was associated with differences in IMF content and possibly growth in a Duroc population, whereas no effect on backfat thickness and drip loss of the meat were detected. A considerable and significant contrast of approximately 1% IMF was observed between certain genotype classes. We conclude that the A-FABP locus is involved in the regulation of intramuscular fat accretion in Duroc pigs.

Adipose Tissue↗
PubMed1998

A learning model of binge eating: cue reactivity and cue exposure.

In the present article, a learning model of binge eating is presented. It has been hypothesized that, parallel to drug intake, the craving and excessive food intake of binge eaters is cue controlled. Research in support of the model is reviewed and a series of predictions about clinical and non-clinical issues is derived from the model. Amongst other things, the model predicts that binge eating might be successfully treated with cue exposure and response prevention. Practical issues are discussed and preliminary pilot studies on cue exposure for bingers are reviewed.

Animals↗
PubMed1998

Molecular epidemiology of American trypanosomiasis in Brazil based on dimorphisms of rRNA and mini-exon gene sequences.

American trypanosomiasis is transmitted in nature via a sylvatic cycle, where Trypanosoma cruzi interacts with wild triatomines and mammalian reservoirs, or via a domestic cycle where the parasite comes into contact with humans through domiciliated triatomines. The pool of T. cruzi isolates consists of sub-populations presenting a broad genetic diversity. In contrast to the heterogeneity suggested by isoenzyme analysis, PCR amplification of sequences from the 24S alpha rRNA gene and from the non-transcribed spacer of the mini-exon gene indicated dimorphism among T. cruzi isolates, which enabled the definition of two major parasite lineages. In the present study, 157 T. cruzi isolates obtained from humans, triatomines and sylvatic mammalian reservoirs from 12 Brazilian states were analysed by the 24S alpha RNA and mini-exon typing approaches. The stocks were classified into the two proposed lineages and according to the domestic or sylvatic cycle of the parasite. Data presented provide evidence for a strong association of T. cruzi lineage 1 with the domestic cycle, while in the sylvatic cycle both lineages circulate equally. Molecular typing of human parasite isolates from three well-characterised endemic regions of Chagas disease (Minas Gerais, Paraiba and Piaui) and from Amazonas State, where T. cruzi is enzootic, suggests that in some endemic areas in Brazil there is a preferential linkage between both cycles mediated by lineage-1 stocks.

Animals↗
PubMed1998

PCR detection of lentiviral GAG segment DNA in the white blood cells of sheep and goats.

A PCR assay for the detection of small ruminant lentiviral gag DNA (provirus) in the white blood cells of sheep and goats was developed and compared with a serological test (AGIDT). A sample of the DNA prepared from the white blood cells in 3 ml of blood from 208 sheep and goats from 18 different flocks was subjected to PCR assay. One of 85 animals from flocks accredited under the Dutch national MVV/CAEV control programme was positive by PCR while none was positive by AGIDT. In infected flocks, the AGIDT appeared slightly more sensitive, but preliminary results show that the sensitivity of the PCR assay may be further improved by increasing the number of monocytes tested. The PCR assay, however, was clearly more sensitive in detecting animals in the early stages of infection. With the use of a set of mixed primers and probes, the assay was able to detect the variety of CAEV and MVV strains occurring in the field.

Animals↗
PubMed1998

Dissociation of the CD4 and CXCR4 binding properties of human immunodeficiency virus type 1 gp120 by deletion of the first putative alpha-helical conserved structure.

To evaluate conserved structures of the surface gp120 subunit (SU) of the human immunodeficiency virus type 1 (HIV-1) envelope in gp120-cell interactions, we designed and produced an HIV-1 IIIB (HXB2R) gp120 carrying a deletion of amino acids E61 to S85. This sequence corresponds to a highly conserved predicted amphipathic alpha-helical structure located in the gp120 C1 region. The resultant soluble mutant with a deleted alpha helix 1 (gp120 DeltaalphaHX1) exhibited a strong interaction with CXCR4, although CD4 binding was undetectable. The former interaction was specific since it inhibited the binding of the anti-CXCR4 monoclonal antibody (12G5), as well as SDF1alpha, the natural ligand of CXCR4. Additionally, the mutant gp120 was able to bind to CXCR4(+)/CD4(-) cells but not to CXCR4(-)/CD4(-) cells. Although efficiently expressed on cell surface, HIV envelope harboring the deleted gp120 DeltaalphaHX1 associated with wild-type transmembrane gp41 was unable to induce cell-to-cell fusion with HeLa CD4(+) cells. Nevertheless, the soluble gp120 DeltaalphaHX1 efficiently inhibited a single round of HIV-1 LAI infection in HeLa P4 cells, with a 50% inhibitory concentration of 100 nM. Our data demonstrate that interaction with the CXCR4 coreceptor was maintained in a SUgp120 HIV envelope lacking alphaHX1. Moreover, in the absence of CD4 binding, the interaction of gp120 DeltaalphaHX1 with CXCR4 was sufficient to inhibit HIV-1 infection.

Amino Acid Sequence↗
PubMed1997

[Abdominal wall metastasis following surgical removal of colorectal carcinomas].

Abdominal wall metastases after laparoscopic resection of colorectal cancer have been reported by various authors. It appeared that abdominal wall metastases occur more frequently after laparoscopic than after conventional, open resection of colorectal cancer. However, the frequency of abdominal wall metastases after laparoscopic surgery varies from only 0 to 1.9% in centres with sufficient relevant experience, whereas after conventional resections the frequency is 0.8-3.3%. A randomized clinical study comparing laparoscopic with conventional resection of colon cancer is necessary to assess the optimal surgical approach to colon cancer. Such a trial has been set up.

Abdominal Muscles↗