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T Walter

Publications and source records attributed to T Walter.

At least 37 records · Page 2Linked to original sources
PubMed1999

Specific binding of the E2 subunit of pyruvate dehydrogenase to the upstream region of Bacillus thuringiensis protoxin genes.

During sporulation, Bacillus thuringiensis produces inclusions comprised of different amounts of several related protoxins, each with a unique specificity profile for insect larvae. A major class of these genes designated cry1 have virtually identical dual overlapping promoters, but the upstream sequences differ. A gel retardation assay was used to purify a potential regulatory protein which bound with different affinities to these sequences in three cry1 genes. It was identified as the E2 subunit of pyruvate dehydrogenase. There was specific competition for binding by homologous gene sequences but not by pUC nor Bacillus subtilis DNA; calf thymus DNA competed at higher concentrations. The B. thuringiensis gene encoding E2 was cloned, and the purified glutathione S-transferase-E2 fusion protein footprinted to a consensus binding sequence within an inverted repeat and to a potential bend region, both sites 200-300 base pairs upstream of the promoters. Mutations of these sites in the cry1A gene resulted in decreased binding of the E2 protein and altered kinetics of expression of a fusion of this regulatory region with the lacZ gene. Recruitment of the E2 subunit as a transcription factor could couple the change in post exponential catabolism to the initiation of protoxin synthesis.

Amino Acid Sequence↗
PubMed1999

A death in our street.

How do neighbours relate to the dying, and what effect does a death have on a neighbourhood? After briefly reviewing related literature, the article explores the concepts of reciprocity and solidarity, using the recent work of Michael Young to highlight limitations in the work of Philip Abrams. The potential of suffering to generate neighbourhood solidarity in an increasingly affluent and private society is considered.

Altruism↗
PubMed1999

Anaemia and iron deficiency disease in children.

Iron deficiency is the single most common nutritional disorder world-wide and the main cause of anaemia in infancy, childhood and pregnancy. It is prevalent in most of the developing world and it is probably the only nutritional deficiency of consideration in industrialised countries. In the developing world the prevalence of iron deficiency is high, and is due mainly to a low intake of bioavailable iron. However, in this setting, iron deficiency often co-exists with other conditions such as, malnutrition, vitamin A deficiency, folate deficiency, and infection. In tropical regions, parasitic infestation and haemoglobinopathies are also a common cause of anaemia. In the developed world iron deficiency is mainly a single nutritional problem. The conditions previously mentioned might contribute to the development of iron deficiency or they present difficulties in the laboratory diagnosis of iron deficiency.

Anemia, Iron-Deficiency↗
PubMed1998

Prevention of iron-deficiency anemia: comparison of high- and low-iron formulas in term healthy infants after six months of life.

OBJECTIVES: For bottle-fed babies or nursing infants who receive milk supplements, the American Academy of Pediatrics recommends the use of iron-fortified infant formula. Because these recommendations have not been universally adopted, the hematologic effects of currently available low-iron formulas need to be determined. STUDY DESIGN: Healthy Chilean 6-month-old infants (without iron-deficiency anemia, born at term weighing > or 3.0 kg) who were totally or partially weaned from the breast were randomly allocated in a double-blind fashion to receive high-iron (n = 430) or low-iron formula (n = 405), containing an average of 12.7 mg/L or 2.3 mg/L, respectively, of elemental iron as ferrous sulfate. Iron status was determined at 12 months. RESULTS: The prevalence of iron-deficiency anemia was not different in the high- and low-iron groups (2.8% versus 3.8%, p = 0.35). Nevertheless, infants receiving high-iron formula had somewhat higher levels of hemoglobin and serum ferritin, greater mean cell volumes, and lower erythrocyte protoporphyrin levels (p < 0.005). CONCLUSIONS: Although high-iron formulas are more efficacious in improving iron status, currently available low-iron formulas may prevent iron-deficiency anemia in selected healthy, term infant populations with otherwise poor sources of dietary iron after 6 months of life. Formulas with relatively small amounts of iron appear to prevent iron-deficiency anemia. We speculate that the optimal level of iron fortification likely lies somewhere between the current levels in high- and low-iron formulas.

Anemia, Iron-Deficiency↗
PubMed1998

Evidence of altered central nervous system development in infants with iron deficiency anemia at 6 mo: delayed maturation of auditory brainstem responses.

Iron deficiency anemia has long been thought to have effects on the central nervous system (CNS). Finding direct evidence of this in human infants, however, has been challenging. Auditory brainstem responses (ABRs) provide a noninvasive means of examining an aspect of the CNS that is rapidly maturing during the age period when iron deficiency is most common. ABRs represent the progressive activation of the auditory pathway from the acoustic nerve (wave I) to the lateral lemniscus (wave V). The central conduction time (CCT, or wave I-V interpeak latency) is considered an index of CNS development because myelination of nerve fibers and maturation of synaptic relays lead to an exponential reduction in the CCT from birth to 24 mo. In 55 otherwise healthy, 6-mo-old Chilean infants (29 with iron deficiency anemia and 26 nonanemic control infants), the CCT was longer in those who had been anemic at 6 mo, with differences becoming more pronounced at 12- and 18-mo follow-ups despite effective iron therapy. The pattern of results--differences in latencies but not amplitudes, more effects on the late ABR components (waves III and V), and longer CCTs (as an overall measure of nerve conduction velocity)--suggested altered myelination as a promising explanation, consistent with recent laboratory work documenting iron's essential role in myelin formation and maintenance. This study shows that iron deficiency anemia in 6-mo-old infants is associated with adverse effects on at least one aspect of CNS development and suggests the fruitfulness of studying other processes that are rapidly myelinating during the first 2 y of life.

Anemia, Iron-Deficiency↗
PubMed1998

High absorption of fortification iron from current infant formulas.

BACKGROUND: Estimations of iron absorption from infant formulas are based on 20-year-old data. Data about iron bioavailability from currently used infant formulas are scarce, considering that during the last decades, formulas have had modifications that could affect iron absorption. METHODS: Bioavailability of isotopically labeled iron (55Fe and 59Fe) from several infant formulas administered to contraceptive-using women between the ages of 30 to 50 years was measured. Six infant formulas and one follow-on formula were compared with a powdered, whole cow's milk, and the results were normalized to an absorption of 40% from a reference dose of iron. RESULTS: Iron bioavailability from the infant formulas was consistently higher (19%), contrasting with the low value (4%) of the unmodified cow's milk (p < 0.0001). Iron absorption of the follow-on formula was intermediate (13%). Formulas with 8 mg/l iron and one with 7 mg/l supply approximately 1 mg of absorbed iron, assuming a consumption of 750 ml/day of formula. This amount covers the iron needs of most infants during their period of greatest vulnerability. Formulas containing 12 mg/l iron would allow the absorption of approximately twice the infant iron requirements. CONCLUSIONS: Current infant formulas have a high iron bioavailability, which is an appealing argument for lowering the level of iron fortification in these products.

Absorption↗
PubMed1998

[Indoor air pollution in southeast Santiago, Chile].

BACKGROUND: Indoor air pollution could play an important role in the susceptibility to respiratory diseases of vulnerable individuals, such as elders and infants. AIM: To evaluate indoor air pollution in a low income population of South East Santiago. SUBJECTS AND METHODS: A domiciliary survey of contaminant sources was carried out in the bouses of a cohort of 522 children less than one year old. Using a case-control design, 121 children consulting for respiratory diseases were considered as cases and 131 healthy infants of the same age and sex were considered as controls. In the houses of both groups, active monitors for particulate matter (PM10) and passive monitors for NO2 were installed. RESULTS: Forty two percent of fathers and 30% of mothers were smokers, and in two thirds of the families there was at least one smoker. Eighty five percent used portable heaters in winter. Of these, 77% used kerosene as fuel. Only 27% had water heating appliances. The rest heated water on the kitchen store or on bonfires. Most kitchen stoves used liquid gas as fuel. Twenty four hour PM10 was 109 +/- 3.2 micrograms/m3. Mean indoor and outdoor NO2 in 24 h was 108 +/- 76.3 and 84 +/- 53.6 micrograms/m3 respectively. Indoor NO2 levels were related to the use of heating devices and smoking. No differences in PM10 and NO2 levels were observed between cases and controls. CONCLUSIONS: There is a clear relationship between indoor pollution and contaminating sources. Indoor NO2 levels are higher than outdoors.

Air Pollution, Indoor↗
PubMed1997

[The aortic arch as the source of a peripheral arterial embolism].

HISTORY AND CLINICAL FINDINGS: On the day before admission a 68-year-old woman had an acute episode of incomplete ischaemia of the left lower arm. She had no known heart disease and her general condition was unchanged. There were no palpable pulses in the cold and pale lower arm. Sensory and motor functions of the left hand were slightly impaired. Arterial embolisation was suspected. INVESTIGATIONS: The blood picture was normal, erythrocyte sedimentation rate 20/50 mm, C-reactive protein elevated to 7.0 mg/l. There was no evidence of clotting abnormality. The resting ECG showed normal sinus rhythm. Doppler ultrasound gave a systolic pressure of 80 mm Hg over the radial artery and 50 mm Hg over the ulnar artery, with a systemic systolic pressure of 140 mm Hg. No intracardiac thrombi were seen on echocardiography. Transoesophageal echocardiography revealed a 2 x 3 cm hypermobile mass in the distal aortic arch, most likely a thrombus as the source of the embolus. Contrast computed tomography and digital subtraction angiography also demonstrated the mass. TREATMENT AND COURSE: At first heparin (bolus of 5000 IU, then 1000 IU/h) was infused. One day after the diagnosis had been established thrombectomy of the aortic arch and embolectomy of the left brachial artery were performed without complication. The patient was discharged on the 15th post-operative day on a maintenance dose of phenprocoumon. Histological examination of the surgical specimen from the aorta showed a separating thrombus on an ulcerating atherosclerotic plaque. CONCLUSION: The importance of the thoracic aorta as a source of emboli is often underestimated. Transoesophageal echocardiography is a reliable method to demonstrate aortic thrombi.

Aged↗
PubMed1997

[QT dispersion in surface ECG and QT dynamics in long-term ECG in patients with coronary heart disease in the chronic post-infarct stage with and without ventricular tachyarrhythmias--correlation with other risk parameters].

QT-dispersion (QTD) in 12-lead surface-ECG and QT-dynamics in Holter-ECG, defined as the time-course of the frequency corrected QT-interval (mQTc), were determined in 42 patients with coronary artery disease in chronic postinfarction stadium without ventricular tachyarrhythmias (CAD/VTA-) and in 24 CAD patients with ventricular tachyarrhythmias (CAD/VTA+). 14 healthy volunteers served as control group (CG). Correlations with hemodynamic data (LVEF, severity of CAD) and with other risk-parameters (ventricular late potentials, short-time heart rate variability) were calculated. QTD in CAD/VTA-was significantly higher compared to CG (48.4 ms+/- 19.6 vs 31.4 ms +/- 9.8, p < 0.05). There were no intergroup differences in QT-dynamics. CAD/VTA+ patients showed the highest QTD-values (59.5 ms +/- 31.1, p < 0.05 compared to CG/CAD/VTA0) and a significantly altered QT-dynamics compared to CG/CAD/VTA- (mQTc: 431.3 ms +/- 38.8 vs 400.8 ms +/- 25.5 vs 406.3 ms +/- l0.6, p < 0.05). Only parameters of QTD were significantly correlated to severity of CAD (r = +0.41, p < 0.01) and to LVEF (r = 0.43, p < 0.01). We did not find significant correlations between the parameters of QT-dispersion/QT-dynamics among one another and to the risk-parameters. These results indicate that the QT-dispersion in CAD-patients also in chronic post-infarction stadium is elevated and that CAD-patients with VTA are characterized by an altered QT-dynamics. Parameters of both methods are independent of other validated risk-parameters. So the measurement of QT-dispersion and QT-dynamics as markers of inhomogenous repolarization could contribute to an improvement of risk-stratification of CAD-patients.

Coronary Disease↗
PubMed1997

Milk inhibits and ascorbic acid favors ferrous bis-glycine chelate bioavailability in humans.

The chemical properties of ferrous bis-glycine chelate allow for its use as a fortificant in fluid, high fat vehicles. This chemical form may also protect iron from the inhibitory or enhancing effects of the diet on iron absorption. Alternatively, iron bis-glycine chelate may be absorbed by a mechanism independent of an individual's iron stores. To test these hypotheses, the bioavailability of iron bis-glycine chelate added to water and milk was studied using a double-isotopic method in two groups of 14 women. Iron absorption from aqueous solutions of 0.27 mmol/L (15 mg/L) of elemental iron as either iron bis-glycine or ferrous ascorbate was not significantly different (34.6 and 29.9%, respectively). There were significant correlations between (log) iron absorption of iron bis-glycine with (log) serum ferritin (r = -0.60, P < 0.03) and with (log) iron absorption from ferrous ascorbate (r = 0.71, P < 0.006), suggesting that iron bis-glycine chelate bioavailability is indeed affected by iron stores. Iron absorption of iron bis-glycine given in milk was significantly lower (P < 0.002) than when given in water, with values of 11.1 and 46.3%, respectively (standardized to 40% absorption of the reference dose). With the addition of 0.57 mmol/L ascorbic acid (100 mg/L), iron absorption of iron bis-glycine given in milk increased significantly from 11.1 to 15.4% (P < 0.05). These findings show that milk and ascorbic acid affect iron bis-glycine chelate bioavailability and also demonstrate that iron stores may influence its bioavailability as well. The good bioavailability of iron bis-glycine makes this compound a suitable alternative to be considered in iron fortification programs.

Adult↗
PubMed1997

Iron, anemia, and infection.

The data on the relationship between iron deficiency and infection are conflicting. Some researchers conclude that mild iron deficiency is beneficial for immunity, whereas others contend that any deficit is not good for immunity. Additionally, infection or inflammation generate anemia and profound changes in iron metabolism mediated by cytokines. These changes are important confounders to consider in assessments of iron status.

Anemia, Iron-Deficiency↗
PubMed1997

The ideology and organization of spiritual care: three approaches.

The development of holistic, multidisciplinary care of the terminally ill has prompted discussion of what spiritual care might mean, but how can this be done in what is largely a secular context? This paper analyses the three options. (1) The idea of the hospice as a religious community enables total care to be given, but conflict can develop as such institutions expand and take on less devout staff. (2) An organizationally less problematic approach, fitting a widespread understanding of religion, is that only some people are religious and they may be referred by staff to the chaplain--but this undermines the goal of holistic care. (3) Recent discussion of spiritual needs, however, argues that everyone has a spiritual dimension, entailing a search for meaning. All staff can help in this area, so this approach is welcomed by nurses seeking to practice holistically and also by chaplains seeking to expand their domain, but it also has certain costs. The article concludes by raising some problems that may emerge if this third approach becomes institutionalized.

Christianity↗
PubMed1997

Analysis of motile oligodendrocyte precursor cells in vitro and in brain slices.

Oligodendrocyte precursor cells are purported to migrate over long distances into the various brain regions where they differentiate into oligodendrocytes and fulfill their appropriate tasks, i.e., myelination of axons. Here we characterize motile oligodendrocyte precursor cells in detail. Video-time lapse analysis was performed on isolated precursor cells in single cell cultures, in co-culture with cerebellar microexplants, and in living brain slices. Motility analysis of individual cells was combined with electrophysiological, immunological, and morphological characterizations. Translocation of the cell bodies was not continuous but occurred in waves. All motile cells exhibited a simple morphology and most, but not all, of them expressed the A2B5 epitope in vitro. Patch clamp analysis of the motile cells confirmed that they belong to the O-2A lineage. The percentage of motile cells, as well as their velocities, were enhanced on substrate-coated laminin in comparison to poly-L-lysine. Motility was not influenced by the presence of cerebellar microexplants. O-2A progenitor cells did not migrate strictly along neurite fascicles which were projected from the microexplants. Glial progenitor cells in situ also did not strictly migrate along the main direction of the axonal fibers of the corpus callosum but rather traversed the fibers with an overall direction toward the cortex. After Lucifer Yellow filling of the motile progenitor cells in situ, we could demonstrate that they were dye-coupled to yet unidentified cells of the corpus callosum.

Animals↗
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↗