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Biomedical subjects

J Schmitz

Publications and source records attributed to J Schmitz.

244 records · Page 14Linked to original sources
PubMedDate not supplied

Are follicular dendritic cells, macrophages and interdigitating cells of the lymphoid tissue productively infected by HIV?

Numerous data demonstrate that lymphoid tissues represent a major HIV reservoir and sites of virus replication. To gain more information about the phenotype of cells in which HIV replicates in the lymphoid tissue, we applied HIV RNA hybridization technique in combination with immunohistochemistry on 10 lymph nodes and 2 lymphoepithelial cysts (LEC) of the parotid gland. In addition, to determine whether or not follicular dendritic cells (FDC) are important targets for HIV, we also analysed isolated and sorted FDC from 4 lymph nodes. The tissues showed follicular hyperplasia and heavy RNA signals in the germinal centres (GC), where diffuse labelling in the light zone as well as single cells with > 50 silver grains were present. The extrafollicular parenchyma contained only a few productively infected cells. The diffuse labelling was intimately related to the FDC network. However, electron microscopic examination and in situ hybridization on isolated FDC did not provide convincing evidence for virus replication in these cells. Virus-producing cells in the GC were almost exclusively CD45RO+, CD57- T cells. Macrophages with HIV RNA were mainly found in LEC of the parotid gland. S-100+ interdigitating cells of the T-dependent zone were HIV RNA-. However, some large S-100+ cells in the squamous epithelium covering the LEC or lying subepithelial did express HIV RNA. These findings suggest that local factors (cytokines?) in the lymphoid tissue probably influence the expression of HIV.

Dendritic Cells↗
PubMedDate not supplied

A carbon-13 breath test to characterize glucose absorption and utilization in children.

After the administration of a 5% glucose-water solution that contained tracer amounts of the stable nonradioactive isotope 13C, breath samples were collected from five children with congenital glucose-galactose malabsorption and five with severe small bowel villous atrophy and chronic diarrhea. The 13CO2 breath test curves of the children with the congenital malabsorption and chronic diarrhea were compared with each other and with those from three healthy children and four infants with severe malnutrition but no diarrhea. The breath test curves from the children with glucose-galactose malabsorption and from those with diarrhea were significantly different from those of the other two groups, a finding consistent with impairment of glucose absorption. The [13C]glucose breath test clearly identified the children with severe glucose malabsorption. Further studies are required to determine whether less severe cases of carbohydrate malabsorption also can be identified using the parameters described in our study.

Breath Tests↗
PubMedDate not supplied

Simulation of complex movements using artificial neural networks.

A simulated network for controlling a six-legged, insect-like walking system is proposed. The network contains internal recurrent connections, but important recurrent connections utilize the loop through the environment. This approach leads to a subnet for controlling the three joints of a leg during its swing which is arguably the simplest possible solution. The task for the stance subnet appears more difficult because the movements of a larger and varying number of joints (9-18: three for each leg in stance) have to be controlled such that each leg contributes efficiently to support and propulsion and legs do not work at cross purposes. Already inherently non-linear, this task is further complicated by four factors: 1) the combination of legs in stance varies continuously. 2) during curve walking, legs must move at different speeds, 3) on compliant substrates, the speed of the individual legs may vary unpredictably, and 4) the geometry of the system may vary through growth and injury or due to non-rigid suspension of the joints. This task appears to require some kind of "motor intelligence". We show that an extremely decentralized, simple controller, based on a combination of negative and positive feedback at the joint level, copes with all these problems by exploiting the physical properties of the system.

Animals↗
PubMedDate not supplied

[Anderson's disease. Clinical and morphologic study of 7 cases].

Anderson's disease is a rare autosomic recessive condition involving the transport of fat through the intestinal mucosa, which could be due to a defect in the intestinal form (B48) of apolipoprotein B. Isolated cases and one important series only have been reported. We wish here to complete the description of the disease. Seven children (age 6 months to 13 years at time of diagnosis) were followed for one month to 15 years. They presented with a malabsorption syndrome, malnutrition, fatty diarrhea (steatorrhea 4-18 g/24 h), failure to thrive (height -1 to -5.5 SD for age) and sometimes disappearance of deep tendon reflexes. Biologically they had signs of malabsorption, hypocalciuria, osteoporosis, low serum iron, decreased levels of vitamins A and E, and hypo-alpha- (50-127 mg/100 ml) and beta- (73-175 mg/100 ml) lipoproteinemia due to decreased levels of plasma cholesterol (40-70 mg/100 ml), and phospholipids (34-67 mg/100 ml); apolipoproteins A1 (26-69 mg/100 ml and B (21-44 mg/100 ml) were also low. After a fatty meal, triglycerides and apolipoproteins did not increase and chylomicrons did not appear. Jejunal biopsies showed the characteristic aspect of enterocytes loaded with lipid droplets. On electron microscopy, these fat droplets were seen in the cytoplasm but neither in the endoplasmic reticulum and the Golgi complex nor in the intercellular spaces. They did not appear to be enclosed in membranes and differed from chylomicrons by their size and density. The disease could thus be due to an abnormal apolipoprotein B48, which would prevent its binding to triglycerides and thus the formation of chylomicrons.

Adolescent↗
PubMedDate not supplied

[Chronic neutropenia and Crohn's disease in childhood. Report of 2 cases ].

Two children in whom Crohn's disease complicated the course of chronic neutropenia are reported. These two cases had other features in common: consanguinity of the parents, relatively good clinical tolerance of neutropenia and almost complete lack of blood and marrow eosinophils. The possible relationships between the 2 diseases are discussed.

Adolescent↗