OBJECTIVES: To evaluate the effect of glutamine-supplemented polymeric enteral formulas on the recovery of gut-permeability abnormalities in critically ill patients. METHODS: Twenty-three patients were randomized to receive a conventional casein-based enteral formula (ADN), ADN plus glutamine in a dose of 0.15 g x kg(-1) x d(-1) or ADN plus 0.30 g x kg(-1) x d(-1) of glutamine for 8 d. The lactulose mannitol permeability test (L/M) was performed at baseline and at the end of the study. Nineteen healthy volunteers served as controls for the L/M test. RESULTS: An increase in permeability compared with control subjects was observed in patients at baseline (mean +/- standard error of the mean; L/M ratio: 0.11 +/- 0.03 and 0.025 +/- 0.004, respectively; P < 0.02). The L/M ratio improved after the period of enteral nutrition as a whole (initial L/M: 0.11 +/- 0.03, final L/M: 0.061 +/- 0.01; P < 0.03), but no difference was found between groups. CONCLUSIONS: Even though polymeric enteral nutrition was associated with a significant improvement in the L/M ratio, glutamine supplementation did not show a specific influence in improving recovery of gut permeability in critically ill patients.

Adult↗

PubMedDate not supplied

Signal transduction of somatostatin receptors negatively controlling cell proliferation.

Somatostatin acts as an inhibitory peptide of various secretory and proliferative responses. Its effects are mediated by a family of G-protein-coupled receptors (sst1-5) that can couple to diverse signal transduction pathways such as inhibition of adenylate cyclase and guanylate cyclase, modulation of ionic conductance channels, and protein dephosphorylation. The five receptors bind the natural peptide with high affinity but only sst2, sst5 and sst3 bind the short synthetic analogues. Somatostatin negatively regulates the growth of various normal and tumour cells. This effect is mediated indirectly through inhibition of secretion of growth-promoting factors, angiogenesis and modulation of the immune system. Somatostatin can also act directly through sst receptors present on target cells. The five receptors are expressed in various normal and tumour cells, the expression of each receptor being receptor subtype and cell type specific. According to the receptor subtypes, distinct signal transduction pathways are involved in the antiproliferative action of somatostatin. Sst1, 4 and 5 modulate the MAP kinase pathway and induce G1 cell cycle arrest. Sst3 and sst2 promote apoptosis by p53-dependent and -independent mechanisms, respectively.

Animals↗

PubMedDate not supplied

Electron contamination in 60Co gamma-ray beams.

All radiotherapy photon beams are accompanied to some extent by secondary electrons which originate in interactions with source hardware, collimator, shadow tray, and/or the air through which the beam passes. Skin sparing, the shape of the dose buildup curve, and the depth of the dose maximum are all influenced by this electron "contamination." The present study of a 60Co source employs a flat ion chamber to measure dose buildup curves in polystyrene at source distances of 72 to 200 cm, with an open beam or a filter of Lucite, Cu, Pb-loaded acrylic, or Ba- or Pb-loaded nonbrowning glass placed 57 cm from the source, using 5 X 5, 20 X 20, and 35 X 35-cm2 beams as defined at 80 cm SSD. The effect of electron generation in the air was studied by placing a He-gas-filled plastic bag in the beam. A value of about 12% is estimated for the lowest relative dose obtainable with a polystyrene phantom in a "clear" 60Co gamma-ray beam of 1-cm diameter.

Cobalt Radioisotopes↗

PubMedDate not supplied

Performance characteristics of an orthovoltage x-ray therapy machine.

Performance characteristics sufficient to provide physical data base specific to the Siemen's Stabilipan 2 orthovoltage x-ray therapy machine are presented. Operating conditions covering the working range of the unit from 100 to 300 kVp are selected. Beam quality, output, the central axis depth dose, relative output factors, field flatness, uniformity index, and filtration characteristics of the beams are studied. Selected results are reported.

Humans↗

PubMedDate not supplied

Comparison of measured and calculated dose distributions around an iridium-192 wire.

The relative dose distribution around a 5.0-cm-long piece of 192Ir wire has been measured using LiF chips. Measurements were made at distances of 0.25 to 5.0 cm away from the source and distances of 0.0 to 4.0 cm along the source. In addition, measurements were also made at several distances along the axis of the source. Attention was paid to the errors associated with these measurements. A comparison was made between a commercial software program, ISODOS, an analytical solution to the Sievert integral, and the measurements. Good agreement was obtained at distances along and away from the source. Major disagreements were found at points along the source axis.

Humans↗

PubMedDate not supplied

Cationic polypeptides modulate in vitro association of low density lipoprotein with arterial proteoglycans, fibroblasts, and arterial tissue.

Polymers of lys (plys) and arg (parg) were found to be efficient inhibitors of the formation of complexes between low density lipoprotein (LDL) and human chondroitin-6-sulfate-rich proteoglycans. Displacement curves indicate that efficiency was dependent on molecular weight. Inclusion of alanine in the polymer up to a 1:1 molar ratio (plys,ala) has a moderate effect on displacing capacity. Poly-L-lys (plys) and poly-L-arg (parg) exhibited similar displacing ability. Inclusion of tryptophan in plys and parg diminished their effect, whereas inclusion of serine in plys,ser (3:1) improved it. Plys (18.3 kD) stimulates LDL binding to human fibroblasts. This may be due to the association of polylysine to LDL, leading to an increase in its positive charge. These more positively charged LDL may have an increased association with the negatively charged region of the apolipoprotein B/E receptor. Perfusion experiments on rabbit aortic segments were used to measure the influx of 125I-LDL into the intima and to study the effect of basic polypeptides. Plys in a 10:1 molar ratio decreased the LDL uptake by approximately 25% when added to the system together with the LDL or in experiments in which the tissue segments were pre-perfused with plys, and LDL was added after elimination of the plys. The results suggest that polycationic polypeptides, due to their strong affinity for sulfated proteoglycans, interfere with the interactions of LDL with components of the arterial extracellular matrix.

Arteries↗

PubMedDate not supplied

Identification of Apo B-100 segments mediating the interaction of low density lipoproteins with arterial proteoglycans.

The interactions of low density lipoprotein (LDL) and apolipoprotein (apo) B-100 segments with chondroitin-6-SO4 rich aortic proteoglycans aggregate (CSPG) were studied by using quantitative frontal elution affinity chromatography. The affinity of the agarose-CSPG was higher for LDL than for very low density lipoprotein and high density lipoprotein was not bound. LDL from different individuals had dissociation coefficients (Kd) from 28 to 179 nM. Experiments with tryptic hydrolysates of apo B suggested that the capacity of LDL to bind with CSPG resides in the protein. Nine apo B-100 hydrophilic peptides, 12 to 26 amino acids long, were selected, and three were found to interact with the agarose-bound CSPG: apo B P-1 (LRKHKLIDVISMYRELLKDLSKEA, residues 4230 to 4254), apo B P-2 (RLTRKRGLKLATALSLSNK, residues 3359 to 3377), and apo B P-11 (RQVSHAKEKLTALTKK, residues 2106 to 2121). These peptides competed with LDL for binding to the agarose-bound and soluble CSPG; apo B P-2 was the most effective. This correlates with Kd values: 63, 86, and 82 microM for apo B P-2, P-1, and P-11, respectively. The peptides shared an excess of positive-charged side chains. Apo B P-2 belongs to the lys- and arg-rich, LDL-receptor domain. Apo E also binds to the agarose-proteoglycan. The results suggest that apo B regions with sequences and charge distributions analogous to those of residues 3359 to 3377, 4230 to 4254, and 2106 and 2121 are among those responsible for the interaction of LDL with intima-media CSPG.

Aorta↗

PubMedDate not supplied

Double lumen dissecting aneurysms of the internal carotid artery in fibromuscular dysplasia: case report.

A young man with cerebral infarction, skeletal, cardiac and renal malformations was found to have on angiography a rare lesion involving the cervical left internal carotid artery, formed by the superposition of two arterial lumina. Anti-platelet therapy did not prevent thrombosis of the lesion and reinfarction. Extracranial-intracranial bypass graft was performed, followed by excision of the arterial lesion. Pathological examination revealed fibromuscular dysplasia and dissecting aneurysm. The few reported cases associating fibromuscular dysplasia of the internal carotid artery with dissecting aneurysm are reviewed. Surgical therapy is recommended in such cases when symptomatology progresses. Fibromuscular dysplasia occasionally coexists with somatic malformations, suggesting a congenital origin of this condition.

Abnormalities, Multiple↗

PubMedDate not supplied

Camp Jamie.

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Adaptation, Psychological↗