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D Reinhardt

Publications and source records attributed to D Reinhardt.

At least 91 records · Page 5Linked to original sources
PubMed1997

Presenilins are processed by caspase-type proteases.

Presenilin 1 (PS1) and presenilin 2 (PS2) are endoproteolytically processed in vivo and in cell transfectants to yield 27-35-kDa N-terminal and 15-24-kDa C-terminal fragments. We have studied the cleavage of PS1 and PS2 in transiently and stably transfected hamster kidney and mouse and human neuroblastoma cells by immunoblot and pulse-chase experiments. C-terminal fragments were isolated by affinity chromatography and SDS-polyacrylamide gel electrophoresis and sequenced. The processing sites identified in PS1 and PS2 (Asp345/Ser346 and Asp329/Ser330, respectively) are typical for caspase-type proteases. Specific caspase inhibitors and cleavage site mutations confirmed the involvement of caspase(s) in PS1 and PS2 processing in cell transfectants. Fluorescent peptide substrates carrying the PS-identified cleavage sites were hydrolyzed by proteolytic activity from mouse brain. The PS2-derived peptide substrate was also cleaved by recombinant human caspase-3. Additional processing of PS2 by non-caspase-type proteases was also observed.

Amino Acid Sequence↗
PubMed1997

Angiotensin-I-converting enzyme DD genotype is a risk factor of coronary artery disease.

Coronary artery disease (CAD) is a polygenic disease whose phenotypic manifestation depends on the interaction of a number of environmental factors. A number of genes, including the angiotensin-I-converting enzyme (ACE) gene, have been implicated in the pathogenesis of CAD. ACE could affect smooth muscle cell and fibroblast migration and proliferation, low-density lipoprotein (LDL) oxidation and endothelial cell function; these are all important factors in atherosclerosis. A polymorphic variant of the ACE gene correlates with higher circulating ACE levels and carries an increased risk of myocardial infarction, and cardiomyopathies. In this study, we sought to determine the distribution of ACE genotypes and the frequency of allele D in patients undergoing coronary angiography at our institution. DNA from 196 patients with angiographically proven CAD and 96 controls without CAD was amplified by polymerase chain reaction (PCR). The primers flanked the region of the ACE gene (intron 16) where the insertion (I) or deletion (D) of a 287-bp fragment results in the I/D polymorphism. PCR amplification of alleles I and D resulted in 490- and 190-bp products, respectively. In the control group, the relative allele frequencies of the polymorphism were similar to those of previously published European studies. The ACE genotype DD was present in 37.3% of patients with CAD as compared to 23.4% in the controls (p < 0.001, odds ratio 1.95, 95% confidence intervals (CI) 1.06-3.57). There was no association with the history of prior myocardial infarction. The genotype distribution in patients with single-vessel involvement was not significantly different from controls (p = 0.14). However, the DD genotype was significantly more common in patients having multivessel CAD when compared to single-vessel disease, indicating an association of this polymorphism with the extent of CAD. ACE genotype DD is more common in patients with multivessel CAD as compared to controls and to patients with single-vessel involvement, indicating that genotype DD is a genetic risk factor for extensive, multivessel CAD.

Aged↗
PubMed1997

Nebulization of a bovine surfactant in cystic fibrosis: a pilot study.

Cystic fibrosis (CF) is a lethal disorder which results in excessive airway secretions and in chronic inflammation of the airways. In vitro and in vivo studies have shown that a lack of surfactant results in the closure of the small airways. In this pilot study, we aimed to determine whether surfactant administered by aerosol might improve lung function on a short-term basis in patients with CF. In a randomized, crossover double-blind pilot study, 120 mg of a lipid-extracted bovine surfactant (Alveofact) or placebo was aerosolized to five young adult patients with CF over a period of 30 min for five consecutive days. The sample size had the power of 90% to detect an increase in forced expiratory volume in one second (FEV1) of 15% (p < 0.05). Jet nebulization of surfactant produced particles of which more than 75% were the respirable range (< 5 microns). The inhalations were well tolerated. No changes in serum antibody titres against the surfactant proteins-B and -C (SP-B/SP-C) were observed. No differences in FEV1 and forced vital capacity were found before, and 30 or 90 min after, the inhalation. This pilot study shows no acute or short-term benefits of surfactant inhalation in young adults with cystic fibrosis. However, a beneficial effect of exogenous surfactant cannot be excluded before other reasons for a lack of effect, such as insufficient quantity delivered, inhomogeneous distribution or inhibition of the surfactant in the lungs, have been completely ruled out.

Administration, Inhalation↗
PubMed1996

Long-term effects of formoterol and salbutamol on bronchial hyperreactivity and beta-adrenoceptor density on lymphocytes in children with bronchial asthma.

Long-term treatment with short-acting beta 2-sympathomimetic drugs has recently been suggested to be due to a rise in asthma mortality. This effect has been attributed to an increase in bronchial hyperreactivity, a desensitization of beta 2-adrenoceptors and/or a rebound effect after cessation of the therapy. Formoterol, a new long-acting beta 2-symathomimetic drug, has been reported to possess not only bronchodilatation but also antiinflammatory effects. The aim of the present study was to investigate whether long-term effects of salbutamol and/or formoterol could deteriorate asthma management. Therefore, in a trial lasting 90 days, we evaluated the effects of the two drugs on lung function, on the protection they provided against inhalative provocation with histamine, and on tachyphylaxis as monitored by the beta-adrenergic density on mononuclear leukocytes (MNL). Two groups of 11 children each with stable asthma were treated with daily doses of either 4 x 200 micrograms salbutamol or 2 x 24 micrograms formoterol in monotherapy. The lung function was measured six times during the trial period, on day 1, and on day 90, before and after inhaling the drug and at all investigations both with and without histamine provocation. In both groups, the bronchodilatory effect of either formoterol or salbutamol remained constant. The lung function values before and after drug inhalation (specific airway resistance sRAW, forced expiration volume FEV1, vital capacity VC) did not alter significantly. After histamine provocation, the protection was more pronounced in the formoterol group. No changes in the beta-adrenoceptor density on MNL and no significant side effects were seen throughout the trial period. We therefore conclude that formoterol protects significantly better against the bronchial challenge with histamine than does salbutamol. Both drugs did not deteriorate the lung function in asthmatic children. In addition, there was no evidence that long-term treatment leads to a desensitization of beta 2-sympathomimetic effects.

Adrenergic beta-Agonists↗
PubMed1996

Surfactant subfractions during nosocomial infection in ventilated preterm human neonates.

Long after resolution of the neonatal respiratory distress syndrome, deterioration of respiratory function in ventilated premature infants during severe nosocomial infections is commonly observed. Based on an increased oxygen demand and ventilatory support, impairment of the pulmonary surfactant system was hypothesized to occur. The clinical course of 10 premature neonates (764 +/- 57 g, 26.6 +/- 0.4 wk) with nosocomial infection mainly due to Staphylococcus epidermidis was divided into four periods in each individual patient: "before deterioration" (average 8 to 11 d of life), "deterioration" (11 to 17 d), "peak" (17 to 22 d), and "recovery" (22 to 24 d). A total of 810 airway specimens were obtained by small volume lavage (1 ml/kg bw), pooled to yield appropriate amounts for differential centrifugation into two distinct subfractions known as large surfactant aggregates (LA) and small surfactant aggregates (SA). "Before deterioration" the amount of phospholipids recovered was constant, and the two fractions were characterized by electron microscopic morphology and biochemical analysis. In the LA fraction lamellar body-like lipid structures were demonstrated, and the phospholipid composition was typical of pulmonary surfactant in premature neonates with a high content of phosphatidylcholine and phosphatidylinositol. With "deterioration" and "peak" the masses of total phospholipids and of phosphatidylcholine recovered were reduced (p < 0.05). At the same time the mass ratio of SA/LA for phosphatidylcholine decreased from 0.32 +/- 0.10 to 0.18 +/- 0.03, indicating a more pronounced decrease of the SA fraction (p < 0.05). The phospholipid composition in the LA fraction did not change during the course of nosocomial infection. In the SA fraction a decrease of phosphatidylcholine and a concomitant increase in lysophosphatidylcholine were observed at the "peak" of the infection. We concluded that, in ventilated premature neonates during nosocomial infection and respiratory deterioration, changes in phospholipid subfractions occur, possibly indicating impairment of pulmonary surfactant metabolism. These findings may be important when considering treatment of acute lung injury with nebulized exogenous surfactant.

Age Factors↗
PubMed1995

Binding properties and protease stability of recombinant human nidogen.

Recombinant human nidogen was obtained from transfected kidney cell clones as a 150-kDa protein with a three-globule structure. It was modified by sulfation and O-glycosylation and a lower level of N-glycosylation than mouse nidogen. Recombinant nidogens of both species were, however, indistinguishable in their affinities for laminin-1 and a recombinant laminin gamma 1 chain fragment and showed a similar binding to collagen IV and the heparan sulfate proteoglycan perlecan. The two nidogens were also equivalent in the promotion of ternary complex formation between these ligands, indicating that this function has been conserved during mammalian evolution. Fewer zinc-binding sites could be identified in human nidogen and correlated with a lower capacity of zinc to prevent binding to laminin and collagen IV. Most remarkable was the greater sensitivity of human nidogen to endogenous proteolysis in cell culture, yielding fragments of 90-145 kDa. Studies with several exogenous proteases, including thrombin and leucocyte elastase, showed lack of stability of the N-terminal globular domain G1 in contrast to what was found for mouse nidogen. Since such degradation could be important for basement membrane remodelling, this difference between human and mouse may be biologically significant.

Amino Acid Sequence↗
PubMed1995

Effects of a low birthweight infant formula containing human milk levels of docosahexaenoic and arachidonic acids.

Long-chain (LC) polyunsaturated fatty acids (PUFA) (LCP) are considered conditionally essential nutrients for low birth weight infants (LBWI). Therefore, enrichment of LBWI formulae with metabolites both linoleic (omega-6) and alpha-linolenic (omega-3) acids at levels typical for human milk has been recommended. However, previous feeding trials with LCP-enriched formulae evaluated only a dietary supplementation with omega-3 LCP from fish oils alone or with both omega-3 and omega-6 LCP at levels considerably lower than usual human milk contents. We studied the effects of an LBWI formula providing the major omega-3 and omega-6 LCP, docosahexaenoic and arachidonic acids, in amounts similar to those in average human milk. Twenty-seven LBWIs were enrolled in this study when they tolerated full enteral feeding (> or = 130 ml milk/kg/day). Infants either received their own mother's milk (n = 8, birthweight 1218 +/- 146 g, gestational age 30.2 +/- 1.5 weeks, mean +/- SD) fortified with protein and minerals (FM-85, Nestle Ag, Munchen, Germany; dosage 5 g/100 ml milk) or were randomly assigned to blinded batches of an LBWI formula (Prematil, Milupa AG, Friedrichsdorf, Germany) without LCP (n = 10, 1280 +/- 229 g, 31.1 +/- 3.1 weeks) or with LCP (n = 9, 1253 +/- 334 g, 30.4 +/- 3.3 wks.). During the study period of 21 days, the three feeding groups did not differ in growth and feeding tolerances as assessed by occurrence of gastric residuals, spitting, or abdominal distention; however, firms stools were noted more frequently in the two formula groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Arachidonic Acid↗
PubMed1995

Omega-3 fatty acids suppress the enhanced production of 5-lipoxygenase products from polymorph neutrophil granulocytes in cystic fibrosis.

Pulmonary damage in cystic br osis (CF) is associated with chronic inflammation mediated in part by proinflammatory 5-lipoxygenase products (5-LOP, leukotrienes and 5-hydroxyeicosatetraenoic acid) from polymorph neutrophil granulocytes (PMN). The authors studied 5-LOP formation of PMN from CF patients and in vitro effects of added eicosapentaenoic acid (EPA) and fish oil. Circulating PMN were isolated from 10 CF patients without acute infections and 10 control persons of the same age (4-20 years). Total 5-LOP liberation from PMN of CF patients was significantly increased over controls after incubation with the calcium ionophore A23 (1 mumol L-1) without arachidonic acid (AA) (380 +/- 24 vs. 294 +/- 28 pmol mL-1) and with 10 mumol L-1 AA (1303 +/- 104 vs. 1015 +/- 104 pmol mL-1), and there were nonsignificant trends to high values after incubation with 5 mumol L-1 platelet activating factor (PAF, 134% of controls) and 1 mumol L-1 formyl-methionylleucyl-phenylalanine (FMLP, 125%). The addition of 100 micrograms mL-1 fish oil to PMN of CF patients challenged with A23 completely suppressed synthesis of proinflammatory 5-LOP of the 4-series, while inactive 5-LOP metabolites of the 5-series were produced. Added EPA (10 mumol L-1) also suppressed 4-series 5-LOP and significantly reduced leukotriene B4 concentration by 48% from 39.9 +/- 3.2 to 20.6 +/- 11.4 pmol L-1, again with a concomittant increase of inactive 5-series metabolites. The authors conclude that the turnover of endogenous and exogenous AA is enhanced in CF, possibly due to stimulated phospholipase A2 activity. The relatively small effect of the receptor dependent stimuli PAF and FMLP may be caused by a down-regulation of PMN receptors in CF. Supplementation of long-chain omega-3-fatty acids may be beneficial for reducing excessive inflammation in CF patients and should be further evaluated.

Adolescent↗
PubMed1995

Pharmacokinetics of bovine surfactant in neonatal respiratory distress syndrome.

Lung pharmacokinetics of lipid-extracted natural bovine surfactants of different composition and currently used in neonatology were studied in 568 airway specimens from 23 consecutively admitted, small preterm neonates (gestational age, 26.7 +/- 0.3 wk) who were mechanically ventilated for 5 to 7 d in a tertiary care center. In six infants who were mechanically ventilated only, no changes in phospholipid quantity or composition were noted. The other infants were randomly assigned to two groups that received the natural surfactants Survanta or Alveofact, respectively. In the Survanta group (n = 6), exponential decreases were observed in the percentage of phosphatidylglycerol (PG) and sphingomyelin (Sph), while phosphatidylinositol (PI) remained low. In Alveofact-treated neonates (n = 8), PG also decreased exponentially, whereas PI increased linearly during the first week of life to values equivalent to those in infants not treated with surfactant. The exponential disappearance of PG and Sph from repetitive airway samples was utilized to calculate an apparent endogenous pool size, for the time before surfactant treatment, of about 20 mg phospholipids/kg body weight (n = 14). The apparent half-life of PG in the Alveofact group (43 +/- 11 h) was shorter than in the Survanta-treated infants (105 +/- 23 h, p < 0.01), and a similar value was obtained for Sph (97 +/- 21 h, n = 6). There was no correlation between PG or Sph half-life and the amount of surfactant applied. These data for human neonates show a dependence of surfactant clearance and metabolism on the type of bovine surfactant preparation administered.

Biological Products↗
PubMed1995

Aerosol bolus dispersion and effective airway diameters in mildly asthmatic children.

The contribution of aerosol techniques, the estimation of aerosol bolus dispersion and effective airway dimensions, to the clinical diagnosis of paediatric asthma was studied. In 47 children, aged 11 +/- 2 yrs, with mild asthma (forced expiratory volume in one second (FEV1) 83 +/- 9% of forced vital capacity (FVC)) effective airway diameters were derived from the recovery of inhaled 1 micron sebacate droplets. Intrapulmonary dispersion of inhaled boluses of 0.4 micron droplets was studied, by characterizing the concentration distributions of droplets in the exhaled air by their standard deviation and skewness. Effective airway diameters increased in asthmatic subjects with increasing body size, and did not differ from those obtained in 16 healthy children of similar age and height. Standard deviation and skewness of particle boluses exhaled from shallow lung depths were higher in the asthmatic children than the healthy children (e.g. standard deviation 91 +/- 17 ml vs 79 +/- 15 ml, skewness 0.38 +/- 0.16 vs 0.23 +/- 0.16, respectively, for boluses in 140 ml lung depth). The sensitivity and specificity of bolus dispersion to detect alterations in lung function was comparable to that of FEV1/FVC, the most sensitive conventional lung function parameter in the present study. There was no correlation between body height or lung function and bolus parameters. We conclude that aerosol measurements do not provide an obvious benefit for the clinical diagnosis of mild paediatric asthma, but bolus dispersion supplies additional information on alterations in convective gas transport in the diseased lung.

Aerosols↗
PubMed1995

[Retrograde intravenous perfusion as ultima ratio in potential amputation patients with peripheral arterial occlusive disease].

In 21 patients with critical ischemia and/or inflammation of the leg facing possible amputation, retrograde intravenous perfusion (RVP) was used to administer fibrinolytics, vasodilators and antibiotics. Amputation was avoided in 15 patients. In 4 patients, RVP was interrupted due to unsuitable veins for putting in cannulas. After introducing a 3-in-1-Block (Winnie) for analgesia, 7 courses of treatment at least were reached before unbearable pain became a reason for stopping therapy. RVP should, therefore, be considered as the last resort in the treatment of critical ischemia and/or inflammation of the leg of patients facing possible amputation.

Aged↗
PubMed1994

Airway pressure measurements during high-frequency positive pressure ventilation in extremely low birth weight neonates.

OBJECTIVES: Evaluation of a modified, computer-controlled, shutter method to determine the complete intrapulmonary pressure course and to ascertain the expiratory time constant for the respiratory system during high-frequency positive pressure ventilation. DESIGN: Prospective clinical study. SETTING: Neonatal intensive care unit in a university hospital. PATIENTS: Sixteen premature newborns (mean gestational age 26 +/- 2 [SD] wks, birth weight 741 +/- 138 g) were studied at various times during their clinical course. MEASUREMENTS AND RESULTS: Installation of the shutter and air flow interruption did not result in any impairment of clinical and respiratory conditions. Time constants were between 58 and 190 msecs. In six patients, an inadvertent positive end-expiratory pressure (1 to 4.5 cm H2O) was found; in these patients only, expiratory time set at the respirator was < 4 time constants. In 13 measurements of nine patients, measured intrapulmonary peak inspiratory pressure was considerably lower (1 to 5 cm H2O) than that value set at the respirator. CONCLUSIONS: The computer-controlled shutter method is noninvasive and applicable without impairment, even in preterm neonates with birth weights of < 1000 g. This method provides important information to optimize respiratory therapy, particularly knowledge of the individual time constant. To avoid inadvertent positive end-expiratory pressure and gas trapping, expiratory time should be > 4 time constants.

Computers↗
PubMed1993

Mapping of nidogen binding sites for collagen type IV, heparan sulfate proteoglycan, and zinc.

Recombinant nidogen fragments comprising the globular domains G1 plus G2, the rod-like domain, and the rod connected to the globe G3 were prepared from the culture media of transfected human cell clones. In addition, domains G1 and G2 were separated from each other after cleavage with chymotrypsin. The purified fragments were characterized by N-terminal sequences, electrophoresis, electron microscopy, and radioimmunoassays and the cell clones by Northern hybridization. Transfection with a construct comprising a large part of domain G3 showed high mRNA levels but no secreted protein, indicating a protein folding problem. All these fragments were used as soluble and/or immobilized ligands in binding assays. This demonstrated major binding sites on domain G2 for collagen IV and heparan sulfate proteoglycan. Affinity chromatography on zinc- and cobalt-loaded columns showed binding of domains G2 and G3 and the rod. Protein binding, but not metal binding, was abolished by reduction and alkylation of nidogen. This allowed for the isolation of several zinc-binding tryptic peptides, four from G2, two from the rod, and one from the G3 domain. Most of these short peptides contained several histidines that are likely to mediate binding. Zinc inhibited efficiently G3-mediated nidogen binding to laminin at 4 degrees C (IC50 approximately 5 microM) but less at higher temperatures. Similarly, zinc inhibited binding to collagen IV and proteoglycan at low temperatures but not at high (37 degrees C) temperatures. This indicates a complex modulation of nidogen binding to other basement membrane proteins by some, but not all, transition metals. Whether the particularly striking effects shown for zinc are of biological relevance remains to be established.

Amino Acid Sequence↗
PubMed1993

Distribution of myocardial beta-adrenoceptor subtypes and coupling to the adenylate cyclase in children with congenital heart disease and implications for treatment.

In congestive heart failure, down-regulation of myocardial beta-adrenoceptors (beta-AR) due to an elevated sympathetic tone is well known. In infancy and childhood, heart failure is usually related to congenital heart disease (CHD). Therefore, 71 samples of right atrial tissue of infants and children with CHD undergoing cardiac surgery were studied for beta-adrenoceptor density and distribution of the beta 1-/beta 2-AR subtypes. In 49 cases, the coupling of the beta-AR to the adenylate cyclase (AC) was examined. In a further study of 19 myocardial samples, AC was selectively stimulated with beta 1- or beta 2-AR whereas the other subtype was blocked by an antagonist. The following results were obtained: (1) Infants and children with severe acyanotic or cyanotic CHD had severely reduced beta-AR densities. (2) In most of the cases, the beta-AR down regulation is beta 1-subtype selective, but in critically ill newborns with congenital aortic valve stenosis or transposition of the great arteries, there is additional significant beta 2-AR down-regulation. In Fallot patients treated with the beta-antagonist propranolol, a significant increased beta-AR number compared with untreated Fallot patients was found. (3) beta-Adrenoceptor reduction in CHD is correlated with elevated noradrenaline plasma levels, thus proving a sympathetic dysregulation. (4) In CHD with moderate hemodynamic load, beta 2-AR coupling to AC was markedly more efficient than beta 1-AR coupling. The small number of myocardial beta 2-AR produced most of the cyclic adenosine monophosphate. (5) In severe acyanotic and cyanotic CHD, a partial decoupling of the beta 2-AR to the AC occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1993

Does pertussis infection induce manifestation of allergy?

To evaluate whether pertussis induces the development of allergy, a prospective study was performed in 25 children aged 0.8-12.2 years. The patients underwent allergy diagnostics during pertussis infection and at a follow-up visit 8-14 months later. Diagnostic criteria included the medical history of the patients and their families, a modified skin prick test, measurement of serum IgE and radio-allergosorbent test screening for specific sensitizations. At the time of pertussis, serum IgE concentration in the study group was 62 +/- 30 kU/ml. At the follow-up visit, there was a significant increase in serum IgE to 137 +/- 51 kU/ml, which was also significantly higher than IgE in an age-matched control group. Children at a significantly higher risk for developing IgE increase or new allergic sensitizations were those with a family history of allergy or potentially allergic disease in their personal history. Our results indicate that pertussis may induce IgE production in affected children.

Child↗