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Biomedical subjects

J de Vries

Publications and source records attributed to J de Vries.

At least 19 recordsLinked to original sources
PubMed1992

Molecular orbital study on the glutathione-dependent detoxication of ozonides.

The present paper describes a theoretical study on the mechanism underlying the reaction of cellular glutathione (GSH) with polyunsaturated fatty acid ozonides. The reaction can be catalyzed by glutathione S-transferases and leads to detoxication of the ozonides. Semi-empirical molecular orbital computer calculations suggest that the reaction of glutathione with ozonides involves a nucleophilic attack at one of the carbon atoms of the ozonide ring, instead of at one of the peroxidic oxygen atoms of the ozonide ring. This implies a mechanism different from that of the glutathione S-transferase-mediated reaction with hydroperoxides, previously proposed for the glutathione-dependent detoxication of fatty acid ozonides.

Computers↗
PubMed1992

Immune deposits in iris biopsy specimens from patients with Fuchs' heterochromic iridocyclitis.

To investigate whether Fuchs' heterochromic iridocyclitis may be an immune complex vasculitis, we used an immunofluorescence technique to detect immunoglobulins and complement in iris biopsy specimens from nine patients with Fuchs' heterochromic iridocyclitis, 12 patients with other types of uveitis, and nine patients with glaucoma but without uveitis. No specific immune deposits were observed in the irises of the patients with Fuchs' heterochromic iridocyclitis. Immunoglobulin G, IgA, IgM, and complement were detected in patients with Fuchs' heterochromic iridocyclitis and patients with uveitis, and these results differed significantly (P less than .05) from the group without uveitis. The immune deposits were found only in the iris vessel walls. No light-microscopic evidence of an inflammatory vascular process could be detected. Further studies are necessary to investigate whether the immune reactants originate from the circulation or result from local formation.

Adult↗
PubMed1992

Fuchs' heterochromic iridocyclitis is not associated with ocular toxoplasmosis.

To analyze the association between Fuchs' heterochromic iridocyclitis (FHI) and toxoplasmosis, we performed ocular examinations and used various specific laboratory tests to establish a role for Toxoplasma gondii in the pathogenesis of FHI. Results were compared with those for other types of uveitis and healthy controls. Of the 88 patients with FHI, nine (10.2%) had toxoplasmosislike scars, but an association could not be proved by the indirect immunofluorescence antibody test or enzyme-linked immunosorbent assay, or by a test for cellular immunity to Toxoplasma antigen. Analysis of aqueous humor samples for Toxoplasma antibodies in patients with FHI also yielded negative results. On the basis of the negative results of these laboratory tests, we concluded that FHI is not associated with ocular toxoplasmosis.

Adolescent↗
PubMed1992

Lithium prophylaxis and interepisode mood. A prospective longitudinal comparison of euthymic bipolars and non-patient controls.

The mood stabilizing effect of lithium prophylaxis was investigated in a longitudinal design. Eighteen euthymic bipolar outpatients using lithium and 20 non-patient controls completed 13 weekly mood ratings. Groups did not differ in biographical characteristics and pre-test manic and depressive symptomatology. Apart from a higher mean happiness rating in the patient group, no statistically significant differences were found on most mood scores between groups, nor was there a group difference in variability over time. It is concluded that lithium prophylaxis does not have an extreme mood normalizing effect in well-controlled bipolars.

Adult↗
PubMed1992

Comparative study on the toxicity of methyl linoleate-9,10-ozonide and cumene hydroperoxide to alveolar macrophages.

In the present study the in vitro toxicities of methyl linoleate-9,10-ozonide (MLO) and cumene hydroperoxide (CumOOH), a model peroxidative agent, are compared. This was carried out using the inhibition of alveolar macrophage phagocytosis as an assessment of in vitro toxicity. Both agents, MLO and CumOOH caused a dose-dependent decrease in the phagocytosing activity of alveolar macrophages isolated from rat lungs. MLO was found to be three times more toxic than CumOOH. Supplementation of macrophages with vitamin C resulted in a decrease of their sensitivity towards MLO and an increase of their sensitivity towards CumOOH, suggesting that different mechanisms underlie the toxic effects of the compounds concerned. This was supported by the data on GSH and vitamin E depletion. In both cases, depletion of the antioxidant was more extensive on exposure to CumOOH. In addition, following GSH depletion, the sensitivity of the macrophages towards CumOOH was more increased than towards MLO. Further, MLO was not able to enhance the peroxide formation from methyl linoleate (ML), whereas CumOOH initiated the peroxide formation of ML. The results of ESR spin trap experiments further supported that MLO-induced toxicity is independent of lipid peroxidation. From all this it is concluded that both mechanisms known to be of importance for peroxide-induced cell toxicity, i.e., depletion of cellular GSH levels and/or lipid peroxidation are not the main processes causing MLO toxicity in vitro.

Animals↗
PubMed1992

Management of cerebellar infarction with associated occlusive hydrocephalus.

We review here 10 cases of cerebellar infarction and associated occlusive hydrocephalus. Surgical therapy consisted of placement of a permanent shunt in 4, and a temporary external ventricular drainage in 6 individuals. This treatment regimen was effective in 9 cases and remained without adequate response in only 1 patient with multiple supra- and infratentorial infarctions. These results and similar reports from the literature suggest that treatment of the hydrocephalus alone might be sufficient in most cases and should therefore constitute the primary treatment of choice in patients presenting with cerebellar infarction and obstruction of cerebrospinal fluid (CSF) pathways.

Adult↗
PubMed1992

Recombination and UV resistance of Escherichia coli with the cloned recA and recBCD genes of Serratia marcescens and Proteus mirabilis: evidence for an advantage of intraspecies combination of P. mirabilis RecA protein and RecBCD enzyme.

In Escherichia coli, constituents of the main recombination pathway are provided by the genes recA (RecA protein) and recBCD (RecBCD enzyme). Recombination in conjugation experiments and repair of UV damage of E. coli mutants deleted for recA, for recBCD or for recA plus recBCD were restored, although to different degrees, by the cloned recA and recBCD genes from Serratia marcescens or Proteus mirabilis. When both recombination enzymes were from the same species, repair and recombination efficiencies had the order E. coli greater than S. marcescens greater than P. mirabilis. However, the P. mirabilis recA plus recBCD genes resulted in higher levels of repair and recombination than those obtained with one component from P. mirabilis (recA or recBCD) and the other from E. coli or S. marcescens. The data provide evidence for the similarity of RecABCD pathways of recombination among enteric bacteria and suggest an in vivo advantage of an intraspecies combination of P. mirabilis RecA protein and RecBCD enzyme over interspecies combinations. This could point to a cooperation between these basic recombination enzymes. The molecular processes which could be involved are discussed.

Cloning, Molecular↗
PubMed1992

Cardiac autonomic mechanisms associated with borderline hypertension under varying behavioral demands: evidence for attenuated parasympathetic tone but not for enhanced beta-adrenergic activity.

Elevated blood pressure in psychophysiological studies of borderline hypertension is frequently attributed to the effects of increased sympathetic tone, and with few exceptions, the potential parasympathetic contributions have not been considered. Furthermore, of the investigations that have addressed vagal influences upon blood pressure, most have employed invasive pharmacological assessment of parasympathetic tone. In this study, cardiac parasympathetic and beta-adrenergic influences in borderline hypertension were evaluated noninvasively employing respiratory sinus arrhythmia as a vagal index and preejection period as a sympathetic index of cardiac functioning. Subjects were 30 borderline hypertensive and 23 normotensive males (age range, 24-45 years). The ECG, blood pressure, impedance cardiography, and respiration were measured during two baselines (initial and post-task), a memory-comparison reaction time task, the cold pressor, and CO2-rebreathing. Results indicated tonic differences between groups in all cardiovascular variables across tasks, with the exception of pre-ejection period, which showed no group effects at all. Hypertensives additionally manifested somewhat heightened systolic blood pressure reactivity and attenuated cardiac parasympathetic responsivity to specific tasks. Our findings provide no support for an exaggerated cardiac beta-adrenergic tonic level or reactivity in borderline hypertensives. On the other hand, the consistently lower magnitude of respiratory sinus arrhythmia in our hypertensives suggests that reduced parasympathetic control may be involved in the pathophysiology of hypertension.

Adult↗
PubMed1992

Effect of glutardialdehyde on secondary caries in situ.

In this paper the results are presented on the effect glutardialdehyde (GDA) on the in situ demineralization of human enamel and dentine around an artificial gap of 200 microns width. In this model secondary enamel and dentine caries is simulated in situ; the mineral loss was quantified. The results show that a 2-min application of a 2% acidic GDA solution reduces dentine demineralization substantially, but does not influence enamel demineralization. Microradiography showed a reduction of mineral loss values around the gap in dentine by about 30%. The beneficial effect of GDA on dentine is presumably a combined result of collagen fixation, the reduced diffusion of calcium and phosphate ions out of the dentine lesion, and antibacterial action. The results indicate that GDA might play a role in the future reduction or prevention of secondary dentine caries.

Adult↗
PubMed1992

Distribution of surface-membrane molecules on bone marrow and cord blood CD34+ hematopoietic cells.

We have investigated the distribution of membrane molecules on CD34+ hematopoietic cells isolated from human bone marrow (BM) and cord blood (CB). A distinct CD10+ population was present in BM, but it was not detected in CB. Most CD34+ CD10+ cells in BM were B-cell precursors (BCP), because they expressed CD19. However, CD40 and CD37 were found on the majority of CD34+ cells from either BM or CB, demonstrating that these antigens are not restricted to B-lineage CD34+ cells. CD40 and CD37 were lost during culture of CD34+ cells in the presence of interleukin 3 (IL-3), indicating transient expression early in myeloid development. CD13 antigen was detected on virtually all CD34+ cells from BM and CB. Accordingly, CD13 was present on CD34+ CD10+ cells, demonstrating that this structure is not restricted to myeloid CD34+ cells. In contrast, myeloid CD33 antigen was not detected on CD34+ CD10+ cells. Expression levels of CD13 and of CD33 were heterogeneous in BM, reflecting diversity within the resident CD34+ population. CD25 and CD71 were found on a proportion of CD34+ cells from either BM or CB and maintained during culture in IL-3, consistent with a distribution on activated cells. Finally, a variety of adhesion receptors were present on CD34+ cells. These included the alpha 4 beta 1 (VLA-4), alpha 5 beta 1 (VLA-5), and alpha L beta 2 (LFA-1) integrins, as well as ICAM-1, LFA-3, H-CAM, and LAM-1. Expression of adhesion receptors was remarkably similar in BM and CB, and it followed an all-or-nothing pattern that failed to delineate CD34+ subsets. Taken together, our data show that although CD34+ cells from BM constitute a more heterogeneous population, resident and circulating CD34+ cells largely display the same cell-surface molecules.

Antigens, CD↗
PubMed1992

The effect of an experimental mouthrinse on enamel lesion remineralization in vitro.

This paper describes the effect of a 2 ppm fluoride containing, slightly acidic mouthrinse (pH = 6) on the remineralization of enamel lesions in vitro. The rinse was applied twice daily for 2 min, on about 85 microns in depth artificial lesions. Artificial enamel lesions were formed at pH = 5 in a 6% CMC gel. The lesions were subsequently remineralized in vitro in a neutral remineralizing solution (1.5 mM Ca and 0.9 mM phosphate) with or without the application of the rinse. After 3 weeks the samples were evaluated by means of quantitative microradiography. The results showed that a statistically significant reduction in lesion depth occurred of 48 and 29% with or without rinse application, with respect to the original lesion depth. The effect of the rinse compared with no rinse decreased the lesion depth by 40%. The data indicate that application of a slightly acidic rinse with 2 ppm fluoride applied twice a day, stimulates the remineralization at the lesion front and does not lead to blocking of enamel pores observed after acidic, high level F applications (APF).

Animals↗
PubMed1991

Analysis of local antibody production in the vitreous humor of patients with severe uveitis.

We analyzed the local antibody production in vitreous humor samples collected during vitrectomy in patients with severe vision-threatening uveitis. In 24 patients, paired serum and undiluted vitreous humor samples were collected and tested for antibodies against Toxoplasma gondii, herpes simplex virus, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus, and Toxocara canis. Total IgG and the Goldmann-Witmer coefficient were determined. The initial diagnosis of ocular toxoplasmosis could be confirmed in six of the seven patients. The seventh patient showed a local antibody production against herpes simplex virus. One of the three patients with chronic panuveitis at initial diagnosis showed a local antibody production against T. gondii. These last two findings resulted in a change in medical treatment. Analysis of local antibody production in vitreous humor samples is a valuable diagnostic tool.

Animals↗
PubMed1991

Technical improvements in the lateral suboccipital approach for neurovascular decompression of the trigeminal and facial nerves.

Some refinements of the surgical procedure are described in 12 patients (five females, seven males) operated on for neurovascular decompression (ND) in the presence of trigeminal neuralgia and hemifacial spasm. The patients were operated upon in the supine position, in which the use of a lumbar drainage facilitates the dissection from the beginning. The lateral suboccipital approach was performed by means of a semi-osteoplastic craniotomy with the use of bone chips to close the bone defects so that a good cosmetic effect could be achieved.

Adult↗
PubMed1991

A lung function information system.

A lung function information system (LFIS) was developed for the data analysis of pulmonary function tests at different locations. This system was connected to the hospital information system (HIS) for the retrieval of patient data and the storage of the lung function variables of patients to generate follow-up reports and to support financial and administrative management. The application programs were developed in such a way that high flexibility was obtained with respect to the patient-computer-technician interaction. The sampled data are stored on a disc to correct earlier decisions, perform recalculations and reanalyse the data for research purposes. When the measurements performed on a patient are authorized, the sampled data are deleted, except for when they are needed for future research. A distributed computer system was chosen to combine the benefits of a centralized system with those of several stand-alone systems. The main tasks of the central unit are to store collected data and computer programs, generate a final lung function report on laser printer and provide a connection to the HIS. In the satellite computers, which are located close to the lung function equipment, the signals and raw data are processed. Furthermore, the satellite computers were in use for program development and several research projects, and for the offline data processing of the lung function measurements from two other hospitals by means of a modem connection. The LFIS improved the quantity and quality of data acquisition. It resulted in an increased capacity of about 50% concerning spirometry, and facilitated time-consuming complex analyses. It also avoided miscalculations and mistakes in reports previously experienced with hand calculations.

Computer Systems↗
PubMed1991

HGM1: a research-oriented portable heart rate and galvanic skin response monitor.

A convenient portable recording device, HGM1, which allows digital field recording of skin conductance and heart rate data with laboratory levels of precision, is described. Examples of individual data are provided from a study of orienting response habituation, and from students participating in a study of examination anxiety, recorded while they sat scheduled class examinations. These illustrate the potential value of the device in field studies.

Adolescent↗
PubMed1991

The recA-recBCD dependent recombination pathways of Serratia marcescens and Proteus mirabilis in Escherichia coli: functions of hybrid enzymes and hybrid pathways.

The physical maps of cloned recBCD gene regions of Serratia marcescens and Proteus mirabilis were correlated to genes located in this region. The genes thyA, recC, recB, recD and argA were organized as in Escherichia coli. The 3 rec genes code for the 3 different subunits of the RecBCD enzyme and produced enzymes promoting recombination and repair of UV damage in E coli. The recBCD-dependent stimulation of recombination at specific nucleotide sequences called Chi (Chi-activation) was determined in lambda red-gam-crosses. Chi-activation by the different RecBCD enzymes decreased in the order E coli greater than S marcescens greater than P mirabilis. In E coli cloned subunits genes from S marcescens and P mirabilis led to the formation of functional hybrid enzymes consisting of subunits from 2 or even 3 species. The origin of the RecC subunit present in the hybrid enzymes affected the degree of Chi-activation. Further, changes in Chi-activation occurred when the RecD subunit in the enzyme from E coli was replaced by RecD proteins from S marcescens or P mirabilis. This suggested that the RecD subunit determines not only whether or not Chi-activation is possible but also to which extent it occurs. Finally we have reconstituted recombination pathways of S marcescens and P mirabilis by combining the cloned recA and recBCD genes from these species in E coli deleted for recA and recBCD. Both pathways can efficiently promote recombination and repair. Studies are summarized which showed that levels of repair and recombination promoted by the recA-recBCD genes are mostly higher when the recA and recBCD genes came from the same species than from 2 different species (hybrid RecBCD recombination pathway). The data are interpreted to provide evidence that in vivo the RecA protein co-operates with the RecBCD enzyme in recombination and repair of UV damage.

Chromosome Mapping↗