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Biomedical subjects

A Brand

Publications and source records attributed to A Brand.

At least 55 records · Page 3Linked to original sources
PubMed2001

Lipid constituents in oligodendroglial cells alter susceptibility to H2O2-induced apoptotic cell death via ERK activation.

The present work examines the effect of membrane lipid composition on activation of extracellular signal-regulated protein kinases (ERK) and cell death following oxidative stress. When subjected to 50 microM docosahexaenoic acid (DHA, 22 : 6 n-3), cellular phospholipids of OLN 93 cells, a clonal line of oligodendroglia origin low in DHA, were enriched with this polyunsaturated fatty acid. In the presence of 1 mM N,N-dimethylethanolamine (dEa) a new phospholipid species analog was formed in lieu of phosphatidylcholine. Exposure of DHA-enriched cells to 0.5 mM H2O2, caused sustained activation of ERK up to 24 h. At this time massive apoptotic cell death was demonstrated by ladder and TUNEL techniques. H2O2-induced stress applied to dEa or DHA/dEa co-supplemented cells showed only a transient ERK activation and no cell death after 24 h. Moreover, while ERK was rapidly translocated into the nucleus in DHA-enriched cells, dEa supplements completely blocked ERK nuclear translocation. This study suggests that H2O2-induced apoptotic cell death is associated with prolonged ERK activation and nuclear translocation in DHA-enriched OLN 93 cells, while both phenomena are prevented by dEa supplements. Thus, the membrane lipid composition ultimately modulates ERK activation and translocation and therefore can promote or prevent apoptotic cell death.

Apoptosis↗
PubMed2001

Early ethanolamine phospholipid translocation marks stress-induced apoptotic cell death in oligodendroglial cells.

The consequences of H(2)O(2)/Fe(2+)-induced oxidative stress on translocation of ethanolamine phosphoglyceride (EPG) and serine phosphoglyceride (SPG) were studied in an oligodendroglia-like cell line (OLN 93) following 3 days of supplementation with 0.1 mM docosahexaenoic acid (DHA) and a series of polar head group precursors, including N-monomethyl- and N,N-dimethylethanolamine at millimolar concentrations. Added DHA was predominantly esterified in EPG species and those cells enriched in DHA showed enhanced sensitivity to oxidative stress and eventually died by apoptosis. Co-supplements with ethanolamine and DHA resulted in a rapid, but transient, EPG translocation with a maximum at 30 min following stress, as characterized by a trinitrobenzenesulfonic acid reagent. There was no significant translocation of SPG as evidenced by annexin V binding. Unlike SPG, which is usually irreversibly translocated to subserve as a tag for phagocytosis, EPG acted as a signaling molecule with biphasic kinetic characteristics. N-Monomethyl- and N,N-dimethylethanolamine supplements reduced EPG synthesis, prevented its externalization and rescued cells from apoptotic death. Following stress, the fatty acid profile of the externalized EPG showed marked losses in polyunsaturated fatty acids and aldehydes compared with the remaining intracellular EPG. Prevention of EPG species selective translocation to the outer membrane leaflet by altering phospholipid asymmetry may be important in the mechanism of rescue from cell death.

Animals↗
PubMed2001

[Approaches to quality management in public health: current and future prospects].

All institutions in the health care sector are facing increasing competition. Therefore, new management concepts are considered. Current strategies are evaluated, and the efficiency of outputs is questioned. Quality management becomes a powerful instrument for achieving quality and ultimate aims. This development will also be the key to success for public health services.

Forecasting↗
PubMed2001

A less invasive treatment strategy to prevent intracranial hemorrhage in fetal and neonatal alloimmune thrombocytopenia.

OBJECTIVE: The purpose of this study was to evaluate whether a less invasive treatment strategy results in a higher platelet count of the neonate and prevents intracranial hemorrhage in pregnant women who are at risk for fetal or neonatal alloimmune thrombocytopenia. STUDY DESIGN: Between March 1989 and August 2000, 48 women with 56 pregnancies were treated. The population was divided into groups. A diagnostic fetal blood sample was taken in 7 cases that had a history of a sibling with an intracranial hemorrhage (group I; n = 8); treatment was provided, when necessary, with platelet transfusions and maternal administration of immunoglobulin. The other 48 cases, with a history of a sibling with severe thrombocytopenia but without intracranial hemorrhage, were retrospectively divided into group IIa (n = 16) and IIb (n = 32). In group IIa, at least 2 diagnostic fetal blood samples were taken, and when necessary, intrauterine platelet transfusion and immunoglobulin were administered (invasive treatment). In group IIb, no initial diagnostic fetal blood sampling was performed (noninvasive treatment). In 23 cases, immunoglobulin was administered, which was followed by predelivery fetal blood sampling in 8 cases. In 9 cases, only predelivery fetal blood sampling was performed, when necessary, followed by intrauterine platelet transfusion. RESULTS: Results of our noninvasive treatment strategy were comparable to results of the invasive method in the prevention of intracranial hemorrhage (intracranial hemorrhage was not observed). In addition, there was an increasing trend in median platelet count and a lower number of cases with severe thrombocytopenia (<50 x 10(9)/L) in the noninvasive compared with the invasive treatment group (median platelet count, 92 and 31 x 10(9)/L, respectively). CONCLUSION: Our results indicate that a less invasive treatment strategy in patients who are at risk for fetal or neonatal alloimmune thrombocytopenia and who have no history of a previous child who was affected with intracranial hemorrhage seems justified.

Adult↗
PubMed2000

[Evaluation of gradual conversion to a less invasive therapeutic strategy for pregnant women with alloimmune thrombocytopenia in the fetus for prevention of intracranial hemorrhage].

OBJECTIVE: To evaluate a less invasive management strategy for pregnant women with neonatal alloimmune thrombocytopenia without a history of intracranial haemorrhage. DESIGN: Retrospective and descriptive. METHOD: In Leiden University Medical Centre, the Netherlands, in the period 1994-August 1999, 31 women with 32 pregnancies were treated. Six women had a history of a sibling with thrombocytopenia and intracranial haemorrhage and 26 a history of a sibling with (severe) thrombocytopenia without haemorrhage. Treatment options consisted of weekly administered intravenous immunoglobulin (ivIG) to the mother without diagnostic cordocentesis, cordocentesis with foetal blood sampling and intrauterine platelet transfusions to the fetus. In the group without history of intracranial haemorrhage fetal blood sampling and platelet transfusion were gradually abandoned as much as possible. RESULTS: In the children of the treated pregnant women there were no instances of intracranial haemorrhage. In addition, the platelet count in cord blood was higher, compared with patients treated before 1994 and with literature data. CONCLUSION: A less invasive management strategy in case of a history without intracranial haemorrhage seems justified based on results in our population. Administration of ivIG without diagnostic cordocentesis, however, results in a lost opportunity to verify the indication and the effectiveness of treatment.

Contraindications↗
PubMed2000

[Leukodepletion of blood products: a requirement for improvement of quality and safety].

The presence of leukocytes in blood products has no beneficial effect on the recipient, except in special situations such as for patients being prepared to receive an organ transplantation. On the other hand the leukocytes have a number of untoward side effects such as HLA immunisation, non haemolytic febrile transfusion reactions, virus transmission and postoperative infections. In response to a request of the Minister of Health, Welfare and Sports, the Health Council of the Netherlands prepared a recommendation on the need of routine leukodepletion by filtration of blood. Although the introduction of leukodepletion of blood products is favoured, it is emphasized that only data from selected patient groups are available while the costs of leukodepletion are considerable. Therefore, an evaluation of the benefits and cost effectiveness of blood filtration is recommended. It is argued that leukodepletion, already introduced in a number of countries, is now considered to be 'state of the art'. Furthermore product liability, public opinion about blood safety and the precaution duty of manufacturers should be taken into account.

Blood Banks↗
PubMed2000

Survival of donor cells 25 years after intrauterine transfusion.

Persistence of donor leukocytes in the circulation of recipients of intrauterine transfusion (IUT) has been observed up to 5 years after birth. The aim of this study was to determine whether transfusions with nonirradiated, nonleukocyte-depleted donor blood during the fetal period resulted in long-term immunomodulation of the recipient. Twenty-four surviving IUT recipients between 1966 and 1976 were tested for autoimmune disease and autoantibodies at follow-up. Ten had sex-mismatched donors and were therefore informative for chimerism studies using fluorescence in situ hybridization (FISH). Seven female recipients could be tested for chimerism using a Y- chromosome-specific polymerase chain reaction (PCR) because they received at least 1 IUT from a male donor. Nine recipients could be studied for cytotoxic T-lymphocyte precursor (CTLp) and helper T-lymphocyte precursor (HTLp) frequencies because the original donors were available for testing. All surviving IUT recipients were in good health at the time of the examination, and routine laboratory testing revealed no abnormalities. None of the IUT recipients were chimeric as determined by FISH analysis, but Y-chromosome-specific sequences were detected by PCR in 6 of the 7 women. However, the CTLp and HTLp frequencies of the IUT recipients against the donors were comparable to those of the controls. The current study provides evidence that IUT can result in the persistence of donor cells in the recipient for a period longer than 20 years but that it is not associated with immunotolerance or with signs of chronic antigenic stimulation. (Blood. 2000;95:2709-2714)

Anemia, Hemolytic, Congenital↗
PubMed2000

NMR spectroscopic study on the metabolic fate of [3-(13)C]alanine in astrocytes, neurons, and cocultures: implications for glia-neuron interactions in neurotransmitter metabolism.

Nuclear magnetic resonance (NMR) spectroscopy and biochemical assays were used to study the fate of [3-(13)C]alanine in astrocytes, neurons, and cocultures. (1)H- and (13)C-NMR analysis of the media demonstrated a high and comparable uptake of [3-(13)C]alanine by the cells. Thereafter, alanine is transaminated predominantly to [3-(13)C]pyruvate, from which the (13)C-label undergoes different metabolic pathways in astrocytes and neurons: Lactate is almost exclusively synthesized in astrocytes, while in neurons and cocultures labeled neurotransmitter amino acids are formed, i.e., glutamate and gamma-aminobutyric acid (GABA). A considerable contribution of the anaplerotic pathway is observed in cocultures, as concluded from the ratio (C-2-C-3)/C-4 of labeled glutamine. Analysis of the multiplet pattern of glutamate isotopomers indicates carbon scrambling through the TCA cycle and the use of alanine also as energy substrate in neurons. In cocultures, astrocyte-deduced lactate and unlabeled exogenous carbon substrates contribute to glutamate synthesis and dilute the [2-(13)C]acetyl-CoA pool by 30%. The coupling of neuronal activity with shuttling of tricarboxylic acid (TCA) cycle-derived metabolites between astrocytes and neurons is concluded from the use of [4-(13)C]-monolabeled glutamate leaving the first TCA cycle turn already for glutamine and GABA synthesis, as well as from the labeling pattern of extracellular glutamine. Further evidence of a metabolic interaction between astrocytes and neurons is obtained, as alanine serves as a carbon and nitrogen carrier through the synthesis and regulated release of lactate from astrocytes for use by neurons. Complementary to the glutamine-glutamate cycle in the brain, a lactate-alanine shuttle between astrocytes and neurons would account for the nitrogen exchange of the glutamatergic neurotransmitter cycle in mammalian brain.

Acetyl Coenzyme A↗
PubMed2000

Orthodontic, genetic, and periodontal considerations in the treatment of impacted maxillary central incisors: A study of twins.

Treatment of twins each with one impacted maxillary central incisor and a mesiodens is described. Treatment included rapid expansion, extraction of the mesiodens, surgical exposure of the impacted central incisor, and its forced eruption. The impacted incisor was brought into functional position in one patient but was lost in the other because of insufficient root length and high mobility. Orthodontic, genetic, and periodontal considerations of these 2 cases are evaluated.

Adolescent↗
PubMed2000

N-methyl bases of ethanolamine prevent apoptotic cell death induced by oxidative stress in cells of oligodendroglia origin.

A major reason for brain tissue vulnerability to oxidative damage is the high content of polyunsaturated fatty acids (PUFAs). Oligodendroglia-like OLN 93 cells lack PUFAs and are relatively insensitive to oxidative stress. When grown in serum-free defined medium in the presence of 0.1 mM docosahexaenoic acid (DHA; 22:6 n-3) for 3 days, OLN 93 cells release in the medium 2.6-fold more thiobarbituric acid-reactive substances (TBARS) after a 30-min exposure to 0.1 mM H2O2 and 50 microM Fe2+. Release of TBARS was substantially decreased by approximately 20 and 30% on coincubation with either 1 mM N-monomethylethanolamine or N,N'-dimethylethanolamine (dEa), respectively. The protective effect of dEa was concentration- and time-dependent and was still visible after dEa removal, suggesting a long-lasting mechanism of protection. After 24 h following H2O2-induced stress, cell death monitored by cell sorting showed 16% of the cells in the sub-G1 area, indicative of apoptotic cell death. DHA-supplemented cultures showed 35% cell death, whereas cosupplements with dEa reduced cell death to 12%, indicating cell rescue. Although the exact mechanism for this protection is not known, the nature of the polar head group and the degree of unsaturation may determine the ultimate resistance of nerve cells to oxidative stress.

Animals↗
PubMed2000

Selective protection of RBCs against photodynamic damage by the band 3 ligand dipyridamole.

BACKGROUND: All studied photosensitizers for virus inactivation impair RBCs. To reduce damage to the RBCs without affecting virucidal activity, selective protection of the RBCs is necessary. The ability of the band 3 ligand, dipyridamole, to react with singlet oxygen and to increase the selectivity of photosterilization was investigated. STUDY DESIGN AND METHODS: Solutions of dipyridamole were illuminated in the presence of tetrasulfonated aluminum phthalocyanine (AlPcS(4)) and dimethylmethylene blue (DMMB). Solutions of amino acids, RBCs, and vesicular stomatitis virus (VSV) in RBC suspensions were photodynamically treated in the presence or absence of dipyridamole. RESULTS: Illumination of a solution of dipyridamole in the presence of AlPcS(4) or DMMB resulted in changes in the optical spectrum of dipyridamole. The photooxidation of dipyridamole was inhibited by azide and augmented by D(2)O, which suggests the involvement of singlet oxygen. Photooxidation of amino acids and photodamage to RBCs was strongly reduced in the presence of dipyridamole. In contrast, photoinactivation of VSV in RBC suspensions was only slightly affected by dipyridamole. CONCLUSION: Dipyridamole can improve the specificity of photodynamic sterilization of RBC concentrates, thereby increasing the practical applicability of this photodecontamination method.

Antiviral Agents↗
PubMed2000

Immunological aspects of blood transfusions.

Donor selection based on blood group phenotypes, and blood processing such as leukocyte-depletion, gamma-irradiation or washing to remove plasma, are approaches for therapeutic or preventive use to manage the immunological complications of transfusion. Indications for specific components are prescribed in guidelines provided by (inter)national Transfusion Societies. Although the use of guidelines and protocols is in line with modern medicine, these can create a state of tension with the political sense of values to improve the viral safety of blood products and with the commercial exploitation of pooled plasma-products.A century of blood transfusion therapy has facilitated cancer treatment and advanced surgical interventions. The transfusion product has improved progressively, although mostly in response to disasters such as wars and AIDS. Every blood transfusion interacts with the immune system of the recipient. There are, however, very few quantitative figures to estimate the consequences. This review is based on the available literature on the clinical consequences of transfusion induced immunization and modulation. To a large degree the clinical consequences of transfusion induced immune effects are still a mystery.A blood transfusion is a medical intervention, which in many cases remains experimental with respect to the benefit/risk ratio. Ideally, this uncertainty should be communicated to patients and every transfusion included in a study. Such studies preferentially should be randomized because the perceived need for transfusion is associated with clinical conditions with a worse prognosis than those that do not receive transfusion. This difference may mask the interpretation of the transfusion effect. Since the blood supply services in almost all Western countries have been reorganized and nationalized, or at least operate to national quality standards, the measurement of risk: benefit of transfusion, whether political or evidence-based, needs to be reconsidered. Differences in emphasis and responsibilities between transfusion providers and transfusion prescribers will drive the providers to political and liability criteria - ever safer products - that will increase hospital costs with undetermined clinical benefits.

Blood Grouping and Crossmatching↗
PubMed2000

[Foundations--a means for implementing strategic goals and measures in public health].

Social innovations are happening in many critical areas. Foundations make an enduring contribution towards increasing access to innovations in public welfare based on the philosophy that believes state-run organizations are neither efficient nor responsive to the people's changing needs. In this sense, foundations help to close the gap by turning hitherto tolerated conditions into problems and claims to action. The effectiveness of voluntary bodies as advocates of change owes much to their informal nature. In Germany, voluntary actions in Public Health are still underrepresented. Therefore, donors should be more supported by state government through adequate regulations. In addition, funders need to concentrate their efforts on the limited number of areas where they can have the greatest impact.

Forecasting↗
PubMed2000

Association of stress during delivery with increased numbers of nucleated cells and hematopoietic progenitor cells in umbilical cord blood.

OBJECTIVE: Umbilical cord blood can be used as a source of bone marrow repopulating cells for allogeneic stem cell transplantation. Large variations in the frequencies of white blood cells and hematopoietic progenitor cells have been found for umbilical cord blood. These variations may be due in part to specific circumstances during labor and delivery. STUDY DESIGN: In this study we analyzed the relationship between stress factors occurring during parturition and the frequencies of nucleated cells, leukocyte subsets, CD34(+) cells, and hematopoietic progenitor cells, as determined in semisolid medium cultures of umbilical cord blood. RESULTS: We observed that a prolonged first stage of labor resulted in increases in the numbers of nucleated cells, granulocytes, CD34(+) cells, and hematopoietic progenitor cells in umbilical cord blood. Evaluation of parameters that indicate stress of the infant during delivery demonstrated higher numbers of nucleated cells, granulocytes, CD34(+) cells, and hematopoietic progenitor cells in umbilical cord blood from children with lower venous pH. CONCLUSION: Longer duration stress during delivery increased the numbers of nucleated cells, granulocytes, CD34(+) cells, and hematopoietic progenitor cells, possibly by causing mobilization of various cell populations by endogenous cytokines. As long as umbilical cord blood harvesting does not interfere with the delivery, umbilical cord blood collected after stressful deliveries may provide optimal units for hematopoietic stem cell transplantation.

Antigens, CD34↗
PubMed2000

Neonatal and postneonatal mortality in Germany since unification.

BACKGROUND: After unification, the gap in infant mortality rates between the two parts of Germany widened until 1996 before converging. The reasons for these changes have not, so far, been apparent. OBJECTIVES: To investigate trends in neonatal and postneonatal mortality in the eastern (the new Länder) and western (the old Länder) part of Germany after unification in 1990 and to identify the scope for further improvement. DESIGN: Examination of trends in birth weights, birth weight specific neonatal mortality and cause specific postneonatal mortality in the two parts of Germany from 1990 to 1996 and 1997 by analysing routinely available vital statistics data. RESULTS: In both parts of Germany, neonatal mortality fell considerably, by 33 per cent in the east and 17 per cent in the west, from 4.5 and 3.5 per thousand live births in 1990 to 3.0 and 2.9 in 1997, respectively. This was attributable to an improvement in survival of infants at all birth weights but especially among those with very low birth weights, accounting for an estimated 83 to 85 per cent of the overall improvement. The birth weight distribution showed a slight worsening in the new and the old Länder with an increase in the proportion of those under 1500 g and, in the east, a 24 per cent increase in the proportion of high birth-weight infants of 4000 and more grams. Trends in postneonatal mortality revealed a worsening of about 32 per cent in the east from 1990 to 1991 followed by a decline of over 50 per cent up to 1997, leading to comparable mortality rates of 1.8 per thousand live births in the east and 2.0 in the west. While both parts experienced a decrease of 40 to 48 per cent in deaths from all diseases, the decline in deaths because of accidents and injuries was markedly higher in the new Länder although they are still exceeding the western rate by 3.7 per 100,000 live births in 1997. CONCLUSIONS: Since unification, the two parts of Germany underwent a complex process that has led finally to convergence of parameters of infant health that are most likely to have been because of improvements in the quality of perinatal care. To improve infant mortality in Germany, policy measures should focus on preventive rather than curative measures as the proportion of very low birthweight babies is increasing in both parts of Germany.

Birth Weight↗
PubMed2000

Duration tuning in the mouse auditory midbrain.

Temporal cues, including sound duration, are important for sound identification. Neurons tuned to the duration of pure tones were first discovered in the auditory system of frogs and bats and were discussed as specific adaptations in these animals. More recently duration sensitivity has also been described in the chinchilla midbrain and the cat auditory cortex, indicating that it might be a more general phenomenon than previously thought. However, it is unclear whether duration tuning in mammals is robust in face of changes of stimulus parameters other than duration. Using extracellular single-cell recordings in the mouse inferior colliculus, we found 55% of cells to be sensitive to stimulus duration showing long-pass, short-pass, or band-pass filter characteristics. For most neurons, a change in some other stimulus parameter, (e.g., intensity, frequency, binaural conditions, or using noise instead of pure tones) altered and sometimes abolished duration-tuning characteristics. Thus in many neurons duration tuning is interdependent with other stimulus parameters and, hence, might be context dependent. A small number of inferior colliculus neurons, in particular band-pass neurons, exhibited stable filter characteristics and could therefore be referred to as "duration selective." These findings support the idea that duration tuning is a general phenomenon in the mammalian auditory system.

Acoustic Stimulation↗
PubMed2000

Low somatic cell count: a risk factor for subsequent clinical mastitis in a dairy herd.

A case-control study was conducted to evaluate factors measured at the udder inflammation-free state as risk factors for subsequent clinical mastitis. The factors including somatic cell count (SCC), body condition score, milk yield, percentages of milk fat and milk protein, and diseases were evaluated for their association with the results of udder inflammatory response. The results of the response were specified as presence (case) and absence (control) of clinical signs of mastitis. Data on Holstein Friesian cows calving from January 1984 to November 1996 from a commercial farm with low bulk milk SCC were used. Univariable and multivariable random-effect logistic models were used to evaluate the effect of those factors on the risk of clinical mastitis. The following variables were associated with increased odds of case versus control events in the univariable analysis: early lactation period, low SCC, high milk yield, high percentage of milk protein, high percentage of milk fat, low body condition score, retained placenta, and milk fever. For the final multivariable model of all variables used for analysis, only low SCC remained significantly associated with increased risk of subsequent clinical mastitis. The authors concluded that very low SCC during the udder inflammation-free state are associated with increased risk of clinical mastitis.

Animals↗