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T Walter

Publications and source records attributed to T Walter.

At least 55 records · Page 3Linked to original sources
PubMed1996

Complement 5a controls motility of murine microglial cells in vitro via activation of an inhibitory G-protein and the rearrangement of the actin cytoskeleton.

Microglial cells respond to most pathological events by rapid transformation from a quiescent to an activated phenotype characterized by increased cytotoxicity and motile activity. To investigate the regulation of microglial motility by different inflammatory mediators, we studied cultured murine microglia by time-lapse video microscopy and a computer-based motility assay. Microglial cells exhibited a high resting motility. The acute application of complement 5a (C5a) immediately induced intense ruffling of microglial membranes followed by lamellipodia extension within few seconds, while formyl-Met-Leu-Phe-OH, bacterial endotoxin (lipopolysaccharide) or inflammatory cytokines did not increase motility. This process was accompanied by a rapid rearrangement of the actin cytoskeleton as demonstrated by labelling with fluorescein isothiocyanate-phalloidin and could be inhibited by cytochalasin B. A GTP-binding protein was involved in the signal cascade, since pertussis toxin inhibited motility and actin assembly in response to C5a. Chemotactic migration in a gradient of C5a was also completely blocked by pertussis toxin and cytochalasin B. The C5a-induced motility reaction was accompanied by an increase in intracellular calcium ([Ca2+]i) as measured by a Fluo-3 based imaging system. Ca2+ transients were, however, not a prerequisite for triggering the increase in motility; motility could be repeatedly evoked by C5a in nominally Ca(2+)-free solution, while Ca2+ signals occurred only upon the first stimulation. Moreover, conditions mimicking intracellular Ca2+ transients, like incubation with thapsigargin or Ca2+ ionophore A23187, were not able to induce any motility reaction, suggesting that Ca2+ transients are not necessary for, but are associated with, microglial motility. Motile activity was shown to be restricted to a defined concentration range of [Ca2+]i as revealed by lowering [Ca2+]i with BAPTA-AM or increasing [Ca2+]i with A23187. Since complement factors are released at pathological sites, this signal cascade could serve to increase motility and to direct microglial cells to the lesioned or damaged area by means of a G-protein-dependent pathway and via the rearrangement of the actin cytoskeleton.

Actins↗
PubMed1996

[Growth in terms of length of Chilean infants of low socioeconomic status: 1978-1992].

In Chile infant malnutrition is better reflected by the length/age indicator than by weight/length. In this study we will present the progression of length during the first year of life from the year 1978 through 1992 of infants of low socioeconomic status. We selected healthy infants with > 3000 g birth weight and birth length > 0.5 z. According to type of milk feedings they were defined as CM (cow milk) those who were weaned before 4 months of life and EM (exclusive breast milk) those who continued exclusive breast milk (as only source of milk solids permitted) past 6 months. Infants CM of the 1978-80 cohort had a length at birth z +0.21 reaching 1 year with z -0.65, a loss of 0.86 z. Infants from the cohorts of 1982-86 and 1988-92 fell from z +0.15 to z -0.37 (a loss of -0.52 z) and +0.16 to -0.19 (a loss of -0.45 z) between birth and 12 months respectively. EBM infants length also fell significantly (delta z: -1.12, -0.69 and 0.59 respectively). Proteincalorie nutrition was adequate confirmed with weight/age or length/weight curves with means of +0.52 throughout the first year. Analysis of the length curves by regression shows that the slopes of the 3 cohorts are significantly different (< 0.01) for CM and EBM favoring the most recent cohorts. Multiple regression analysis identified association of length at 1 year with birth weight (p < 0.05), birth length (p < 0.01) and socioeconomic index (p < 0.01). We suggest that there is an improvement in the trend of Chilean infants growth in length for the past 20 years, likely due to improvement in socioeconomic level.

Birth Weight↗
PubMed1995

Cellular and topical in vivo inflammatory murine models in the evaluation of inhibitors of phospholipase A2.

Several novel inhibitors of human synovial fluid phospholipase A2 (HSF-PLA2) were evaluated in cellular models of inflammatory mediator release (murine macrophage and human neutrophil) and topical in vivo inflammatory skin models in mice to ascertain the scope of effects which might be observed for PLA2 inhibitors. Potent inhibition of HSF-PLA2 in vitro can be observed with compounds such as scalaradial and ellagic acid, which both have IC50 values of 0.02 microM (using autoclaved [3H]-arachidonic-acid (AA)-labelled Escherichia coli membranes as substrate). Luffariellolide, a manoalide analog, and aristolochic acid are less potent (IC50 = 5 and 46 microM, respectively) in this assay. An interesting observation is that ellagic acid in cellular assays does not inhibit macrophage eicosanoid production and only 30% inhibition of PAF biosynthesis can be obtained at 50 microM in the human neutrophil. Possibly due to its irreversible mechanism of action, scalaradial retained its potent activity in both the macrophage (IC50 for PGE2 production = 0.05 microM) and neutrophil assays (IC50 for PAF biosynthesis = 1 microM). Aristolochic acid is active in these cellular assays (macrophage IC50 = 2.5 microM and neutrophil IC50 = 100 microM), but is consistently less active than either scalaradial or luffariellolide. The relative potencies of these compounds were determined in several murine in vivo inflammatory models such as oxazolone contact hypersensitivity, AA-induced ear edema and phorbol ester (PMA)-induced ear edema. In the mouse model of oxazolone contact hypersensitivity, these PLA2 inhibitors have little effect (< or = 30% inhibition at 400 micrograms/ear) with scalaradial and luffariellolide being less effective than either aristolochic or ellagic acid. PMA-induced ear edema was effectively inhibited by scalaradial, luffariellolide and aristolochic acid (ED50 = 70, 50 and 50 micrograms/ear, respectively) whereas ellagic acid was less effective (ED50 = 230 micrograms/ear). In AA-induced ear edema, these PLA2 inhibitors had minimal effects, as would be expected for compounds which inhibit PLA2. These results, especially those of ellagic acid, suggest that caution should be taken in the extrapolation of potency against a purified human extracellular type PLA2 to the scope of activities these compounds might have in the cellular and in vivo models. The consistency of scalaradial and luffariellolide may be inherent to their irreversible mechanism of action, which is a factor to be accounted for in the extrapolation of enzyme data to cellular and in vivo models.

Animals↗
PubMed1995

Effect of supplementation with an iron-fortified milk on incidence of diarrhea and respiratory infection in urban-resident infants.

To address the hypothesis that increased infectious morbidity is associated with iron supplementation, 783 randomly selected infants were provided with a powdered full fat cow's milk (non-fortified group) and 872 with a powdered acidified full fat cow's milk fortified with 15 mg of iron as ferrous sulfate (fortified group). All infants were followed from birth to 15 months of age with a monthly home visit by a nurse who recorded morbidity occurring during the previous 30 days. At 9 months of age, 15% of infants in each cohort were receiving breast milk only; data for these infants were segregated to make the third group. Episodes (mean +/- SD) of diarrhea/infant/year were 1.06 +/- 1.29, 1.14 +/- 1.37, and 0.82 +/- 1.04 for the fortified, non-fortified and breast-fed groups, respectively; the fortified and non-fortified bottle-fed groups had a very similar incidence of respiratory illness; 2.66 +/- 2.07 and 2.74 +/- 2.24 episodes/infant/year, respectively. The incidence of respiratory illness for both bottle-fed groups was significantly higher than that for the breast-fed group (2.22 +/- 1.84 respiratory episodes/infant/year). We conclude that for the infants the tested form of iron fortified milk, which is sufficient to lower iron deficiency anemia, does not result in an increased incidence of diarrhea or respiratory illness.

Analysis of Variance↗
PubMed1995

The digoxigenin (DIG) system for non-radioactive labelling and detection of nucleic acids--an overview.

The use of non-radioactive nucleic acid probes has increased dramatically over the last years. The convenience of not having to deal with radioactive isotopes combined with the stability and economy of the non-radioactive systems has led to applications in various techniques. One of the most successful labelling and detection systems is based on the hapten digoxigenin. Here, the different methods for labelling nucleic acids with digoxigenin as well as the various possibilities for detection are described. Some typical applications illustrate the utility of the DIG system.

Animals↗
PubMed1995

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Anthropology, Cultural↗
PubMed1994

Corticosteroids as adjunctive therapy for diffuse alveolar hemorrhage associated with bone marrow transplantation. University of Nebraska Medical Center Bone Marrow Transplant Group.

BACKGROUND: Diffuse alveolar hemorrhage is a frequent complication of treating malignancies with high-dose chemotherapy and bone marrow transplantation and is associated with very high mortality. This disorder's association with pulmonary inflammation, its coincidence with marrow recovery, and the usefulness of corticosteroids for treating other pulmonary hemorrhage syndromes provided the rationale for this study. METHODS: We retrospectively studied 65 episodes of diffuse alveolar hemorrhage that has occurred in 63 of 603 consecutively treated patients who had undergone high-dose chemotherapy with bone marrow transplantation. Patients were divided into three groups according to the therapy they had received for diffuse alveolar hemorrhage: supportive therapy alone (n = 12); low-dose corticosteroids (30 mg or less of methylprednisolone or its equivalent; n = 10); and high-dose corticosteroids (more than 30 mg methylprednisolone or its equivalent; n = 43). The primary outcome measures were overall survival and survival to hospital discharge, occurrence of respiratory failure requiring intubation, and development of infections subsequent to the diagnosis of diffuse alveolar hemorrhage. RESULTS: Overall survival at the end of the follow-up period was significantly higher for the high-dose corticosteroid group compared with the supportive therapy group (P = 0.005); however, treatment with low-dose steroids did not increase survival over supportive therapy alone (P = 0.198). In addition, survival to discharge was significantly increased for the high-dose group compared with the other two groups combined (33% versus 9.1%, P = 0.038). Respiratory failure after the diagnosis of diffuse alveolar hemorrhage developed in only 12 of the 22 unintubated patients in the high-dose group compared with 9 of the 10 initially unintubated patients in the other two groups (P = 0.056). Although the incidence of infections was high (40%) subsequent to diffuse alveolar hemorrhage, neither high-dose nor low-dose corticosteroid treatment significantly increased the risk of infections (P > 0.4, all comparisons). CONCLUSIONS: In this study, high-dose corticosteroid therapy for diffuse alveolar hemorrhage related to bone marrow transplantation was associated with improved total survival and survival to hospital discharge, and decreased development of respiratory failure in these patients. These results suggest the therapy is beneficial, and further prospective studies are warranted to verify the effectiveness of the treatment.

Adult↗
PubMed1994

Effect of iron-deficiency anaemia on cognitive skills in infancy and childhood.

Animal experimentation has shown that early iron deficiency irreversibly affects brain iron content and distribution, resulting in neutransmitter and behavioural alterations. Even though extrapolation of animal data is often misleading, iron-deficiency anaemia has been consistently shown to be associated with psychomotor delays in infancy. The areas most involved are language and body balance. In these infants iron therapy, in most cases was not sufficient to reverse psychological effects even after complete correction of haematological measures. These findings may imply that the impact of iron-deficiency anaemia during infancy may be associated with irreversible adverse effects on cognitive performance. Careful follow-up studies of these infants at 5-6 years of age has shown that cognitive disadvantages persist, now assessed with a comprehensive set of psychological tests that reliably predict future competence. Thus, if once anaemia ensues, even timely and adequate iron therapy seems to be ineffective in reversing these behavioural and cognitive disadvantages; the only practical way to approach this problem is by prevention of iron deficiency in infancy. Health authorities, having been shown that treatment of iron deficiency anaemia is already too late to reverse potential deficits, should strive to prevent iron deficiency with adequate food fortification strategies or by supplementing targeted population groups.

Anemia, Iron-Deficiency↗
PubMed1994

Isolation of region specific single-copy probes from human chromosome 1q23-->1q25.

Single-copy sequences of chromosome bands 1q23-->1q25 were enriched by subtractive hybridization of digoxigenin oligonucleotide-labeled DNA from a somatic cell hybrid containing human chromosome 1 with DNA from a somatic cell hybrid containing a deleted human chromosome 1, del(1)(q23q25). These sequences were purified with an immobilized anti-digoxigenin antibody, amplified by polymerase chain reaction (PCR) and cloned. The majority of clones contained single-copy sequences, thus allowing direct screening of human genomic DNA. With pools of probes complex hybridization patterns as well as differences in hybridization patterns between genomes were observed in Southern blotting experiments. Nine clones containing independent single-copy sequences from chromosome bands 1q23-->1q25 were isolated and sequenced to generate sequence-tagged sites (STSs). Using PCR, region specific genomic clones containing large inserts were identified in human genomic lambda phage and cosmid libraries. Thus, region specific genomic probes generated by genomic difference cloning are useful for identifying deletions and rearrangements, for generating STSs and for isolating genomic clones containing large inserts of a particular chromosomal region.

Base Sequence↗
PubMed1994

[Factors which modify the nutritional state of iron: tannin content of herbal teas].

Tannins are natural compounds that abound in herbs, wood and fruits. Their numerous hydroxyl radicals confer them a strong avidity for metals such as Fe, Zn and Cu. This property makes them strong inhibitors for the gastrointestinal absorption of these metals. Our purpose was to determine the tannin content of herbal infusions commonly consumed in Chile and other Latino American countries. The determination was performed from dessicated herbs with the Folin-Denis technique. Yerba mate, tea and oregano had the highest tannin content (117, 100 and 84 mg of tannic acid/g dry herb respectively). An intermediate level (between 20 and 40 of tannic acid/g) was for coca, matico, boldo, palto, laurel, orange and binojo. The lowest level of tannin for paico, cedrón, apio and manzanilla (< 10 mg/g). We conclude that the consumption of herbal teas at or around meals may inhibit the absorption of metals such as Fe, Zn, or Cu by decreasing their bioavailability.

Beverages↗
PubMed1993

Purification and characterisation of the restriction endonuclease ItaI from Ilyobacter tartaricus recognizing 5'-GC decreases NGC-3'.

ItaI, an isoschizomer of the subclass IIW [Kessler and Manta, Gene 92 (1990) 1-248] restriction endonuclease (ENase), Fnu4HI [Leung et al., Nucleic Acids Res. 6 (1979) 17-25], has been isolated from Ilyobacter tartaricus. The ENase has the five-base palindromic recognition sequence, 5'GC decreases NGC-3'. It cleaves behind the second nucleotide and produces a one-nt 5' overhang.

Deoxyribonucleases, Type II Site-Specific↗
PubMed1993

Analgesic activities of PEM-420, the active eutomer of pemedolac.

PEM-420, the active isomer of pemedolac, inhibited the writhing responses induced by phenylbenzoquinone (PBQ), acetic acid, and acetylcholine in mice with ED50's of 0.80, 0.92, and 0.075 mg/kg p.o., respectively. In the rat acetic acid writhing assay, PEM-420 exhibited an ED50 value of 8.4 mg/kg p.o. In the Randall-Selitto test, PEM-420 raised the pain threshold of the yeast-injected paw (ED50 = 0.55 mg/kg p.o.). Like other NSAIDs, PEM-420 inhibited the PBQ-induced production of PGI2 and PGE2 in the mouse peritoneal cavity, with ED50 values of 0.5 and 1.2 mg/kg p.o., respectively. It had weak ulcerogenic liability in rats (acute UD50 = 99 mg/kg p.o. in fasted rats; subacute UD50 = 74 mg/kg/day for 4 days in fed rats). The data indicate that PEM-420 is a potent and safe peripheral analgesic.

Acetates↗
PubMed1993

Pharmacological characterization of WAY-121,520: a potent anti-inflammatory indomethacin-based inhibitor of 5-lipoxygenase (5-LO)/phospholipase A2 (PLA2).

WAY-121,520 inhibited human synovial fluid PLA2 (HSF-PLA2) (IC50 = 4 microM) using arachidonic acid-labeled E. coli as substrate. Further biochemical characterization of WAY-121,520 demonstrated potent inhibition of 5-lipoxygenase (5-LO) activity in the murine macrophage (LTC4, IC50 = 4 nM) and rat PMN (LTB4, IC50 = 10 nM) and an ability to antagonize LTD4 binding to isolated guinea-pig trachea (pKB = 6.0). In vivo anti-inflammatory activity was noted in murine TPA-induced (ED50 = 91 micrograms/ear) and arachidonic acid-induced (66% inhibition at 400 micrograms/ear) ear edema and in leukotriene-dependent antigen-induced bronchoconstriction in the guinea pig (73% inhibition at 50 mg/kg, p.o.). WAY-121,520 represents a novel series of indomethacin-based inhibitors of PLA2 with anti-inflammatory activity resulting from a combination of biochemical activities (inhibition of 5-LO and PLA2 and LTD4 antagonism). This agent may provide added therapeutic efficacy over more selective inhibitors.

Animals↗
PubMed1993

Effect of bovine-hemoglobin-fortified cookies on iron status of schoolchildren: a nationwide program in Chile.

The Chilean School Lunch program, which serves one million children nationwide, was supplied with three 10-g cookies fortified with 6% bovine hemoglobin concentrate, designed to provide 1 mg bioavailable iron per day. A survey of 1000 children was performed after 3 y. Significant differences in hemoglobin concentrations were found in the children from the fortified vs the nonfortified province (P < 0.01). Low serum ferritin values were also significantly more prevalent in the nonfortified group. The effect was evident despite the very low prevalence of anemia in both the fortified and the unfortified school groups. Heme-iron-fortified cookies are a feasible and effective way to improve the iron status of school-age children. In regions of high prevalence of iron-deficiency anemia, the effect of a heme-fortified cookie program should be even more important.

Adolescent↗
PubMed1993

[Changes in the hemogram and in the laboratory parameters indicative of iron metabolism in mild viral infections].

PURPOSE: To assess the duration and intensity of the changes appearing in laboratory values related to iron utilisation during viral infection. MATERIAL AND METHODS: With previous parental consent, 120 eutrophic infants received vaccination with attenuated measles virus or a combination of measles, mumps and rubella viruses as a model of mild viral infection. A number of laboratory tests were performed on day 0 and in two later occasions (4-21, 9-14 or 9-30); these included blood cell counts, ESR, serum iron, total iron binding capacity, transferrin saturation index, free erythrocytic protoporphyrin, serum ferritin, intra-erythrocytic ferritin, direct anti-human globulin test and C-reactive protein. The statistical analyses were done in accordance with ANOVA, Student's t test, Wilcoxon, Kruskall - Wallis, Mann-Whitney and Fisher methods. RESULTS: A significant haemoglobin drop was seen on days 9 and 14 post-vaccination. This descent was > 10 g/L in 8.2% of the cases, and > or = 6 g/L in 19.6%. Serum iron and transferrin saturation decreased significantly, whereas mean corpuscular volume, free erythrocyte protoporphyrin and serum ferritin were significantly increased. All these but protoporphyrin recovered by day 30. Subjects with normal iron metabolism figures on day 0 and those whose thermal variations were above 38 degrees C had greater changes in the figures related to iron metabolism. CONCLUSION: The evaluation of iron metabolism is not reliable if the patient has suffered from infection, although a mild viral one, in the three weeks prior to the study.

Acute Disease↗
PubMed1993

[Congenital aneurysm of the left atrial wall. A case report].

An intrapericardial aneurysm of the left atrial wall in a 28-year-old man is reported. This is a rare congenital anomaly. The patients are usually identified by clinical signs, when complications such as cardiac arrhythmias and systemic embolism occur. Clinical findings including the ECG are non-specific. Cardiomegaly and unusual configuration of the heart are consistantly found, but are not pathognomonic. The diagnosis is usually confirmed by angiocardiography. Echocardiography, computed tomography and/or MRI can contribute to the diagnosis. Operation seems to be indicated if complications are to be avoided.

Adult↗
PubMed1993

Effectiveness of iron-fortified infant cereal in prevention of iron deficiency anemia.

BACKGROUND: Iron deficiency continues to be a common problem among infants throughout the world. Iron-fortified formula is effective in preventing iron deficiency but the benefit of iron-fortified cereal is controversial. METHODS: We compared iron-fortified rice cereal to unfortified rice cereal in infants who were exclusively breast-fed for more than 4 months and to iron-fortified formula in infants who were weaned to formula before 4 months of age. The design was double blind in respect to the presence or absence of fortification iron in the cereal or formula and included 515 infants who were followed on the protocol from 4 to 15 months of age. Rice cereal was fortified with 55 mg of electrolytic iron per 100 g of dry cereal and infant formula with 12 mg of ferrous sulfate per 100 g of dry powder, levels approximating those in use in the United States. Measures of iron status were obtained at 8, 12, and 15 months. Infants with hemoglobin levels of < 105 g/L were excluded from the study and treated. RESULTS: Consumption of cereal reached plateaus at means of about 30 g/d after 6 months of age in the formula-fed groups and 26 g/d after 8 months in the breast-fed groups; these amounts are higher than the 19-g/d mean intake by the 73% of infants who consume such cereal in the United States. Among infants weaned to formula before 4 months, the cumulative percentages of infants excluded for anemia by 15 months were 8%, 24%, and 4%, respectively, in the fortified cereal, unfortified cereal and formula, and fortified formula groups (P < .01 unfortified vs either fortified group; the difference between the two fortified groups was not significant). In infants breast-fed for more than 4 months, the corresponding values were 13% and 27%, respectively, in the fortified and unfortified cereal groups (P < .05). Mean hemoglobin level and other iron status measures were in accord with these findings. CONCLUSION: Iron-fortified infant rice cereal can contribute substantially to preventing iron deficiency anemia.

Anemia, Hypochromic↗