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Biomedical subjects

A Valentin

Publications and source records attributed to A Valentin.

At least 91 records · Page 5Linked to original sources
PubMed1994

[Adherence of isolated Candida albicans strains from HIV+ infected patients to buccal epithelial cells: correlation with serotype, sensitivity to fluconazole and virulence].

During infection by human immunodeficiency virus (HIV), oral pseudomembranous candidiasis frequency is high. Adherence of Candida albicans to epithelial cells constitutes one of the first step in the setting up of candidiasis. Adherence ability of Candida albicans to buccal epithelial cells (BEC) is estimated for 83 isolates. The yeasts are isolated from buccal swabs from HIV+ patients with clinical oropharyngeal candidiasis. Results show that Candida albicans ability to adhere to BEC is variable within isolates; it appears that most of the isolates are weakly adherent. In addition, adherence is not correlated with the serotype A or B of yeasts. We do not either observe any correlation between adherence capacity and sensibility of yeasts to fluconazole. Moreover, no correlation is observed between a group of 13 genetically identical isolates (analysed on 21 loci with isoenzymes method) and their adherence to BEC. Finally, Candida albicans virulence, which is studied in vivo on intravenously infected mouse model, does not seem to be correlated with capacity of each yeast to adhere on BEC in vitro.

AIDS-Related Opportunistic Infections↗
PubMed1993

Duplex sonographic detection of internal jugular venous thrombosis after removal of central venous catheters.

Venous thrombosis is a very common complication of central venous catheters inserted via the jugular or subclavian vein. The aim of this prospective study is to test the suitability of duplex sonography in detecting thrombi in the internal jugular vein after catheter removal and to analyze the number and extent of such thrombus formations. The study group comprised 64 consecutive patients with an average age of 59 +/- 16 years admitted to an internal intensive care unit. In 54 cases the catheters were removed under sonographic control. In 10 cases duplex sonography was carried out within 24 h after removal of the catheters. The data of 63 patients were evaluated. In 40 patients (63.5%), thrombi of varying extent were present in the jugular vein. No significant correlations were found between thrombus formation and the basic disease, duration of cannulation, the type of catheters used, and the mode of heparinization (therapeutic vs. low-dose). Local inflammation signs and local hematoma showed a significantly higher incidence (p < 0.01) in patients with thrombus formation. Duplex sonography lends itself as a valuable diagnostic tool in the diagnosis of thrombus formation in the internal jugular vein after removal of central venous catheters. Sonographic examinations should be carried out in all long-stay patients at an intensive care unit, in whom central venous catheters are inserted repeatedly via the internal jugular vein.

Adult↗
PubMed1993

Babesia divergens: characterization of a 17-kDa merozoite membrane protein.

Large amounts of viable merozoites were purified from in vitro cultures of Babesia divergens by a two-step sieving procedure. A monoclonal antibody produced against B. divergens merozoites, mAb DG7, stained the merozoite plasma membrane and an intra-parasitic linear organelle in indirect immunofluorescence. Immunogold labeling in electron microscopy demonstrated that the antigen recognized by mAb DG7 was localized just beneath the merozoite plasma membrane. Immunoprecipitations of metabolically labeled ([35S]methionine) B. divergens antigens showed that the epitope recognized by mAb DG7 was present on a 17-kDa polypeptide (Bd17) and was shared in all B. divergens geographical isolates tested so far. Bd17 was always present in the in vitro culture supernatants of all these isolates. Furthermore, Triton X-114 phase separation of babesial antigens demonstrated the hydrophilic character of Bd17 which suggests that it is an extrinsic protein present on the cytosol side of the parasite membrane. When added to the culture medium, mAb DG7, purified from ascite fluids, drastically altered the growth of the parasite with concentrations inhibiting 50% of development (IC50) ranging between 16.6 and 26.1 micrograms/ml).

Animals↗
PubMed1993

V3 sequences of paired HIV-1 isolates from blood and cerebrospinal fluid cluster according to host and show variation related to the clinical stage of disease.

The spread of HIV-1 to the nervous system occurs early during infection in a large number of asymptomatic virus carriers. In order to address the question whether the brain is targeted by a group of HIV-1 variants with increased neurotropic properties we have obtained 20 paired isolates from the blood and cerebrospinal fluid (CSF) of patients with varying severity of HIV-1 infection. We determined the nucleotide sequence of variable region 3 (V3) of the gp 120 envelope protein and studied the growth capacity of the virus isolates in primary monocyte/macrophage cultures. Blood and CSF V3 sequences could be grouped according to the host, whereas particular amino acid sequences related to tissue specificity were not identified. Moreover, the majority of HIV-1 isolates, independently of the tissue source, replicated in macrophage cultures. The isolates derived from the brain and blood compartments thus appeared genetically similar and could not be grouped according to their replicative capacities. The genetic distance between paired CSF and blood sequences was more pronounced in the group of patients with AIDS than in asymptomatic virus carriers. These observations indicate that the viruses present in the blood and CSF in the early stage of infection are genetically similar. Different mechanisms of adaptation or immunomodulation of the virus in CSF and blood may account for the increased intra-patient variability observed in the AIDS group.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Intra-operative transluminal angioplasty of the supra-aortic vessels.

Intra-operative transluminal angioplasty of supra-aortic vessels was performed in 9 patients. All subjects had lesions which were considered difficult or impossible to operate upon. In 2 patients a proximal occlusion of the left subclavian artery was dilated. Seven subjects showed severe stenoses of the supra-aortic vessels: common carotid artery: 1, internal carotid artery: 2, external carotid artery: 1, external carotid artery prosthetic graft: 1, brachiocephalic trunk: 1, vertebral artery: 1. All patients suffered from symptoms which corresponded to the site of the lesions in question. Intra-operative angioplasty was primarily successful in all 9 patients. Re-occlusion occurred within a few days in both patients who underwent angioplasty of the subclavian artery. Six of the seven subjects with stenotic lesions remained free of symptoms and of restenosis. In the case of dilatation of a prosthetic graft of the external carotid artery asymptomatic occlusion developed within 8 weeks. In selected cases intra-operative angioplasty is a potentially valuable alternative in the treatment of surgically inaccessible lesions of the supra-aortic vessels.

Adult↗
PubMed1993

Is intra-articular pethidine an alternative to local anaesthetics in arthroscopy? A double-blind study comparing prilocaine with pethidine.

We investigated the per- and postoperative pain-reducing effect of pethidine given intra-articularly (i. art.). Thirty patients subjected to knee joint arthroscopy, diagnostic and surgical procedures, were randomly assigned to one of three groups. Group A consisted of ten patients who received 250 mg prilocaine + 200 micrograms adrenaline (i. art.) in a volume of 50 ml, group B of ten patients who received 200 mg pethidine (i. art.) in 50 ml saline, and group C of ten patients who received 200 mg pethidine + 200 micrograms adrenaline (i. art.) in 50 ml saline. During arthroscopy the patients reported on pain intensity and discomfort using visual analogue scales. Ratings were low and did not differ significantly between the three groups. Two of three patients in each group requested additional analgesics or sedatives due to pain and discomfort, but again with no difference between the three groups. Postoperatively all patients rated their pain intensity at rest and during movement (at 0, 1, 2, 3, 4, 5, 6, 12 and 24 h). The patients receiving pethidine (group B) reported significantly less pain at rest and movement than group A patients, in general at 1-4 h postoperatively. A significant difference was detected between groups B and C at 4 h postoperatively. Calculating the total sum of pain scores, patients receiving pethidine (group B) reported significantly less pain both at rest and during movement than those receiving prilocaine (group A). Furthermore, patients in group B used significantly less analgesics than those in group A. Adrenaline did not potentiate the effect of pethidine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Cellular and humoral immune responses induced in cattle by vaccination with Babesia divergens culture-derived exoantigens correlate with protection.

Previous results with the Babesia divergens gerbil vaccination model were extended in studies with cattle. Two calves were vaccinated with culture-derived B. divergens exoantigens, and two others were treated with control supernatant; both preparations were adjuvanted with Quil-A saponin. A parasite-specific humoral response was observed after the first vaccine injection and was boosted by two succeeding vaccine injections. Sera from the two vaccinated calves immunoprecipitated eight major parasitic proteins (with molecular masses ranging between 17 and 110 kDa) whose patterns were close to those observed in gerbil vaccine assays. The cellular immune response, monitored by lymphoproliferation assays, was slightly delayed in comparison with the humoral response; a significant proliferation occurred only after the second vaccine injection. Mononuclear cell proliferation was dose dependent in the presence of (i) lysates of B. divergens-parasitized erythrocytes, (ii) exoantigens of the whole supernatant, or (iii) protective exoantigens of two low-molecular-mass fractions obtained after supernatant gel filtration chromatography. An infectious challenge was administered 3 weeks after the third vaccine injection, with 3.6 x 10(10) B. divergens-parasitized erythrocytes. Erythrocyte count, rectal temperature, and parasitemia of the animals were monitored daily until they returned to initial values. All parameters indicated that the exoantigens induced protection from B. divergens infection for the two vaccinated calves.

Animals↗
PubMed1992

Thymidine and 3'-azido-3'-deoxythymidine metabolism in human peripheral blood lymphocytes and monocyte-derived macrophages. A study of both anabolic and catabolic pathways.

3'-Azido-3'-deoxythymidine (AZT) is HIV-inhibitory in human macrophages, which is surprising in view of the low AZT phosphorylation reported in macrophage extracts. To elucidate the mechanism of AZT activation, we studied AZT anabolism as well as catabolism in human lymphocytes and macrophages, and compared it to that of thymidine. Thymidine kinase (TK)-specific activity in mitogen-stimulated lymphocytes was 15 times higher than in macrophages. However, the TK activity per cell was only 1.3 times higher, because of the large macrophage cell volume. Total cellular TK activity, but not specific activity, matched the level of intracellular AZT anabolism. The substrate specificity of TK in macrophages strongly suggests that mitochondrial TK2 was the enzyme phosphorylating thymidine and AZT in these cells, whereas it was cytosolic TK1 in stimulated lymphocytes. In vivo thymidine catabolism was extensive, forming thymine and dihydrothymine. In macrophages more than 95% of the added thymidine (0.5 microM) was degraded within 60 min. AZT, in contrast, was not catabolized, which explains the high AZT nucleotide accumulation, a process opposed only by AZTMP excretion. The lack of catabolism together with phosphorylation by TK2 clarifies how AZT can inhibit human immunodeficiency virus in macrophages. The fact that TK2 and not TK1 phosphorylates AZT in macrophages should have important implications for combination chemotherapy.

Chromatography, High Pressure Liquid↗
PubMed1992

Perinuclear cytoskeleton of acrosome-less spermatids in the blind sterile mutant mouse.

The perinuclear cytoskeleton of mammalian spermatids is thought to play a major role in nucleus-acrosome association and in shape changes of the head during spermiogenesis. To test these hypotheses acrosome-less spermatids in blind-sterile mutant mice were investigated for the development of the subacrosomal layer. Immunogold procedures were used for the detection of actin and calmodulin. In addition to various other abnormalities many acrosome-less round and elongating spermatids developed a subacrosomal layer with an actin and calmodulin distribution similar to that observed in normal spermatids. However, in mutant elongating spermatids the apical part of the nucleus was truncated and/or folded. The expected elongation and shaping of the nucleus only occurred in its caudal part associated with an hypertrophied and somewhat ectopic manchette. These abnormalities and those previously observed in mutant and experimental models indicated that the subacrosomal layer may form independently of the acrosome. It is suggested that the subacrosomal filamentous actin is a transitory scaffolding which might be involved in the assemblage of other proteins of the perinuclear cytoskeleton. However, by itself, this layer is not sufficient to ensure a normal shaping of the nucleus. Acrosome-nucleus interactions mediated by the subacrosomal layer seem necessary to shape the cranial spermatid head. The manchette appears to be involved only in the caudal nuclear shaping.

Acrosome↗
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

Endogenous superoxide dismutase activity in two Babesia species.

Babesia hylomysci and B. divergens were studied for superoxide dismutase (SOD) activity by enzyme assay and isoelectric focusing (IEF). In the two Babesia species, parasite-associated SOD is cyanide-insensitive and inhibited by H2O2, indicating that iron is the cofactor metal. Measurements of SOD activity from purified parasites show that the SOD activity detected in Babesia is, for the main part, due to an endogenous enzyme.

Animals↗
PubMed1992

Human immunodeficiency virus type 1 enhances intracellular growth of Mycobacterium avium in human macrophages.

Disseminated Mycobacterium avium infections are common in patients with AIDS and result in a reduced life expectancy. Human monocytes/macrophages are important target cells for both human immunodeficiency virus (HIV) and M. avium. We have studied the interaction in vitro of M. avium and HIV type 1 (HIV-1) in human macrophages. Human monocytes isolated from the peripheral blood of healthy individuals were infected with HIV-1, M. avium, or both. The intracellular growth of M. avium and the replication of HIV-1 were monitored for up to 5 weeks. Intracellular mycobacterial growth was seen in all M. avium infected cell cultures and was paralleled by increased production of interleukin 1 alpha and beta. Preinfection of the macrophages with HIV-1 reduced the interleukin 1 production and accelerated the intracellular growth of M. avium. These findings may explain in part the impaired control of mycobacterial infections seen with patients with AIDS.

Cells, Cultured↗
PubMed1992

Evaluation of vasomotor reactivity by transcranial Doppler and acetazolamide test before and after extracranial-intracranial bypass in patients with internal carotid artery occlusion.

BACKGROUND AND PURPOSE: The aim of this trial was to evaluate the effectiveness of extracranial-intracranial bypass with respect to vasomotor reactivity in patients with internal carotid artery occlusions and absent vasomotor reactivity, comparing them with a control group treated conservatively. METHODS: To test vasomotor reactivity in 104 patients with unilateral occlusion of the internal carotid artery, we measured blood flow velocity in the middle cerebral artery by transcranial Doppler sonography both at rest and after injection of acetazolamide. Among the 39 patients who failed to show increased mean blood flow velocity after the acetazolamide test distal to an occluded internal carotid artery by greater than or equal to 10%, 14 subjects subsequently underwent extracranial-intracranial bypass surgery (group A) and 14 age- and sex-matched subjects in whom no such procedure was done composed the control group (group B). Follow-up examinations were performed 3-6 months postoperatively and in the control group 3-6 months after initial examination. RESULTS: Baseline values of the mean blood flow velocity at rest on the affected side were reduced in both groups compared with the contralateral healthy side (group A, 46.0 +/- 15.1 cm/sec; group B, 48.1 +/- 16.7 cm/sec) and revealed only a marginal increase after acetazolamide. The contralateral side showed a normal blood flow velocity at rest and an adequate response to acetazolamide in both groups. On the follow-up examination group A demonstrated a normalized vasodilatory capacity. Blood flow velocity increased significantly after acetazolamide from 41.9 +/- 13.1 cm/sec to 53.5 +/- 16.0 cm/sec (p less than 0.002). In group B, the compromised vasomotor reactivity remained unchanged. CONCLUSIONS: Our results demonstrate that transcranial Doppler sonography together with the acetazolamide test can identify subjects with reduced vasomotor reactivity distal to an occluded internal carotid artery, who may improve hemodynamically by an extracranial-intracranial bypass.

Acetazolamide↗
PubMed1992

Babesia divergens vaccine.

A vaccine strategy against Babesia divergens bovine babesiosis was successfully developed after perfecting of an efficient in vitro culture. Crude supernatants and purified fractions were able to induce a vaccine protection in gerbils against B. divergens infection. More, supernatants induced an effective vaccine protection in cattle. The role of B. divergens exoantigens of 17, 37, 46, 70 and 90 kDa in the development of the immune response was clearly demonstrated in gerbils, cattle, and man.

Animals↗
PubMed1992

[Transcranial Doppler ultrasound in intensive care medicine].

Transcranial Doppler sonography (TCD) enables measurement of blood flow velocities in the basal intracerebral vessels. The most important applications of TCD in the ICU are the diagnosis and monitoring of vasospasms caused by subarachnoid hemorrhage after rupture of an aneurysm. Further indications are the non invasive diagnosis of critical decreases of cerebral perfusion pressure, the evaluation of brain death and the monitoring of thrombolysis of occlusions of the middle cerebral artery. TCD lends itself as a valuable non invasive bedside-monitoring tool, which enables continuous or intermittent monitoring of intracerebral hemodynamics without strain for the patients. Disadvantages to be mentioned are the dependence of experienced examiners and the long lasting training phase required to achieve the requisite experience.

Blood Flow Velocity↗
PubMed1992

[Intensive care of cerebral hemorrhage].

Critically ill patients with intracerebral hemorrhage require immediate treatment in an intensive care unit. In the acute phase of the disease the patients are endangered from increased intracerebral pressure, respiratory disorders (aspiration!) and hypertension. An adequate intensive care management consisting of sedation, analgesia, intubation and mechanical ventilation, correct body positioning and treatment of hypertension is of decisive importance for the prognosis of these patients. The aim of this report is to discuss the most important therapeutic strategies and arising problems in the course of intracerebral hemorrhage.

Brain Damage, Chronic↗