Biomedical subjects

P Lasch

Publications and source records attributed to P Lasch.

At least 19 recordsLinked to original sources

PubMed2002

Mid-IR microspectroscopic imaging of breast tumor tissue sections.

IR microspectroscopic imaging is a relatively new approach for the examination of tissue sections. In contrast to standard light microscopy based procedures, the IR approach requires neither sample staining nor fixation. The IR spectra of breast tumor tissue sections are obtained via a microscope equipped with a focal plane array detector. This enabled the simultaneous collection of individual mid-IR spectra from thousands of different sample positions with a spatial resolution near the diffraction limit. The analysis of the IR data reveals a high sensitivity of the IR approach toward changes in tissue biochemistry and variations in breast tissue architecture. Moreover, the data demonstrate the need for collecting spectra with high spatial resolution at the level of individual cells. This minimizes problems associated with tissue microheterogeneity and is an essential prerequisite for future studies aimed at developing IR microspectroscopic imaging as a complement to present diagnostic tools for breast cancer.

Breast↗

PubMed2000

Hydrogen peroxide-induced structural alterations of RNAse A.

Proteins exposed to oxidative stress are degraded via proteolytic pathways. In the present study, we undertook a series of in vitro experiments to establish a correlation between the structural changes induced by mild oxidation of the model protein RNase A and the proteolytic rate found upon exposure of the modified protein toward the isolated 20 S proteasome. Fourier transform infrared spectroscopy was used as a structure-sensitive probe. We report here strong experimental evidence for oxidation-induced conformational rearrangements of the model protein RNase A and, at the same time, for covalent modifications of amino acid side chains. Oxidation-related conformational changes, induced by H(2)O(2) exposure of the protein may be monitored in the amide I region, which is sensitive to changes in protein secondary structure. A comparison of the time- and H(2)O(2) concentration-dependent changes in the amide I region demonstrates a high degree of similarity to spectral alterations typical for temperature-induced unfolding of RNase A. In addition, spectral parameters of amino acid side chain marker bands (Tyr, Asp) revealed evidence for covalent modifications. Proteasome digestion measurements on oxidized RNase A revealed a specific time and H(2)O(2) concentration dependence; at low initial concentration of the oxidant, the RNase A turnover rate increases with incubation time and concentration. Based on these experimental findings, a correlation between structural alterations detected upon RNase A oxidation and proteolytic rates of RNase A is established, and possible mechanisms of the proteasome recognition process of oxidatively damaged proteins are discussed.

Hydrogen Peroxide↗

PubMed2000

Detection of pathological molecular alterations in scrapie-infected hamster brain by Fourier transform infrared (FT-IR) spectroscopy.

In this report a new approach for the identification of pathological changes in scrapie-infected Syrian hamster brains using Fourier transform infrared microspectroscopy is discussed. Using computer-based pattern recognition techniques and imaging, infrared maps with high structural contrast were obtained. This strategy permitted comparison of spectroscopic data from identical anatomical structures in scrapie-infected and control brains. Consistent alterations in membrane state-of-order, protein composition, carbohydrate and nucleic acid constituents were detected in scrapie-infected tissues. Cluster analysis performed on spectra of homogenized medulla oblongata and pons samples also reliably separated uninfected from infected specimens. This method provides a useful tool not only for the exploration of the disease process but also for the development of rapid diagnostic and screening techniques of transmissible spongiform encephalopathies.

Animals↗

PubMed1998

The influence of poly-(L-lysine) and porin on the domain structure of mixed vesicles composed of lipopolysaccharide and phospholipid: an infrared spectroscopic study.

Fourier transform infrared (FTIR) spectroscopy has been used to study the thermotropic phase behavior of binary lipid mixtures composed of deuterated phospholipids (PLs) and lipopolysaccharides (LPSs). Furthermore, the influence of an extrinsic high-molecular, polycationic polypeptide (poly-(L-lysine), PLL(500)) and an intrinsic membrane protein (outer membrane protein F, OmpF) on these binary mixtures was investigated by FTIR spectroscopy. "Deep rough" mutant LPS (ReLPS), isolated from Salmonella minnesota R595, and perdeuterated 1,2-dimyristoylphosphatidylethanolamine (DMPEd54) were used as model lipids. Deuteration of one of the lipids permitted the detection of lipid protein interaction with each lipid component separately. For this purpose, the symmetric >CH2 and >CD2 stretching bands were utilized as specific monitors to scrutinize the state of order of the membranes. From the individual phase transition temperatures Tm and the shape of the phase transition profiles, it is established that ReLPS and DMPEd54 are molecularly immiscible. In addition to the two domains of the pure lipid components, a third, domain-like structure is detected that may coexist with these pure domains. This domain-like structure undergoes a gel to liquid-crystalline L1 (beta <--> alpha) phase transition at temperatures distinctly different from that of the respective pure lipid domains. The nature of this type of domain is discussed in terms of a "border region" model that adequately explains the experimentally observed complex phase transition profiles. It is further demonstrated that the extrinsic polycationic polypeptide PLL(500) and the intrinsic, pore-forming protein OmpF isolated from Escherichia coli interact preferentially and highly specifically with the negatively charged ReLPS. Both the synthetic polypeptide and the pore-forming protein increased the tendency of ReLPS and DMPEd54 to segregate into distinct, well-separated domains. Whereas the transition profiles of the ternary system ReLPS/DMPEd54/PLL(500) showed the features of a phase segregation phenomenon not affecting the transition temperatures of the pure lipid components, the ternary system composed of ReLPS/DMPEd54 and OmpF exhibited phase transition curves that were characterized by an unspecific (DMPEd54/OmpF) and a strong and unique (ReLPS/OmpF) type of lipid-protein interaction. Furthermore, semiquantitative estimations supported the supposition that OmpF might be able to induce bilayer asymmetry in preformed symmetrical ReLPS/DMPEd54 vesicles.

Bacterial Proteins↗

PubMed1998

FT-IR microspectroscopic imaging of human carcinoma thin sections based on pattern recognition techniques.

FT-IR microspectroscopic maps of unstained thin sections from human melanoma and colon carcinoma tissues were obtained on a conventional infrared microscope equipped with an automatic x, y stage. Mapped infrared data were analyzed by different image re-assembling techniques, namely functional group mapping ("chemical mapping") and, for the first time by cluster analysis, principal component analysis and artificial neural networks. The output values of the different classifiers were recombined with the original spatial information to construct IR-images whose color or gray tones were based on the spatial distribution of individual spectral patterns. While the functional group mapping technique could not reliably differentiate between the different tissue regions, the approach based on pattern recognition yielded images with a high contrast that confirmed standard histopathological techniques. The new technique turned out to be particularly helpful to improve discrimination between different types of tissue structures in general, and to increase image contrast between normal and cancerous regions of a given tissue sample.

Biomarkers, Tumor↗

PubMed1997

[The role of extracorporeal membrane oxygenation (ECMO) in current neonatology].

Two hundred term or near-term neonates were referred to an ECMO center for severe PPHN associated diseases. In 2 time periods from 1987 to 1991 and from 1992 to December 1995 alternative treatment modes were tried in an attempt to obviate ECMO. During the first time period patients underwent a trial of high-frequency oscillatory (HFOV) ventilation before ECMO. In the second time period patients first received inhaled NO followed by HFOV in non-responders. If this also failed HFOV was combined with iNO. In both time periods about 40% of the patients were spared ECMO treatment by these alternative treatment modalities. INO only benefited 15% of the ECMO candidates who apparently had fared just as well on HFOV alone in the preceding time period. While patients who were improved by iNO were spared HFOV with its potential severe complications, i.e. air leaks and cardiocirculatory instability. More extended long-term studies will have to show which of these 2 treatment modalities (iNO or HFOV) should be given-first priority in an attempt to avoid ECMO in neonates with severe respiratory failure.

Extracorporeal Membrane Oxygenation↗

PubMed1996

Inhaled nitric oxide for avoidance of extracorporeal membrane oxygenation in the treatment of severe persistent pulmonary hypertension of the newborn.

UNLABELLED: Inhaled nitric oxide (NO) is thought to provide a noninvasive therapeutic alternative to extracorporeal membrane oxygenation (ECMO) in the treatment of persistent pulmonary hypertension of the newborn (PPHN). OBJECTIVE: Since January 1993, we have studied inhalation of NO in PPHN patients meeting the ECMO criteria of our institution. We focused on the questions of whether or not the need for ECMO could be obviated and whether differences could be found between NO responders and nonresponders. DESIGN: NO gas was delivered via conventional IPPV ventilation in incrementally increasing concentrations from 20 to 80 ppm. PATIENTS: NO therapy was attempted in ten ECMO candidates with clinical and echocardiographical evidence of PPHN (mean OI 51.9, SD 10.4). RESULTS: At various NO levels (30-60 ppm), five patients showed a significant increase in mean PaO2 (range 32.9-85.9 mmHg). Improvement was transient in three patients (6-10 h) and prolonged in two others (54-80 h); in the latter cases, ECMO was avoided. Five patients did not respond at all to treatment. Responders and nonresponders differed in their mean respiratory tidal volume (8.9 vs 4.18 ml/kg, P <0.05). CONCLUSIONS: In our study, inhalation of NO obviated the necessity of ECMO therapy in only two out of ten PPHN patients. Thus, we would discourage any overoptimistic expectations about the effectiveness of NO therapy in PPHN until larger clinical trials have been performed.

Administration, Inhalation↗

PubMed1996

Inhaled nitric oxide during extracorporeal membrane oxygenation for the treatment of severe persistent pulmonary hypertension of the newborn.

Inhaled nitric oxide (NO) as a complementary treatment was studied in 10 neonates during extracorporeal membrane oxygenation (ECMO) therapy of various persistent pulmonary hypertension of the newborn (PPHN)-associated diseases. At individually different levels of inhaled NO (20-80 ppm), the mean Pao2 increased by 59.7% in 6 responders, but it remained unchanged in 4 nonresponders. Adverse side effects of the NO inhalation were tolerable. It was associated with a reversible decrease of the mean arterial blood pressure in 1 patient. During prolonged NO inhalation, the methemoglobin (met-Hb) level increased to 0.9-4.6% in 6 patients. Based on these preliminary results, we conclude that inhaled NO during ECMO can improve oxygenation in some PPHN patients. Further studies with control groups are needed to determine whether inhaled NO can shorten ECMO treatment or improve the rate of survival among PPHN patients.

Administration, Inhalation↗

PubMed1996

Influence of early postnatal dexamethasone therapy on ventilator dependency in surfactant-substituted preterm infants.

We examined 26 preterm infants with respiratory distress syndrome in a randomized controlled prospective study to determine whether early postnatal dexamethasone therapy (< 2 h; 0.5 mg/kg per day) over 5 days in addition to substitution of surfactant (100 mg/kg) facilitates extubation and the course of RDS. Control (n = 12) and treated (n = 14) groups were comparable in birthweight (mean +/- SD: 1219 +/- 292 versus 1446 +/- 442 g), gestational age (29.3 +/- 2.2 versus 30.6 +/- 2.7 weeks), prenatal characteristics and initial respiratory and blood gas parameters. In both groups one infant died. Infants in the dexamethasone group responded better to surfactant (12/14 versus 3/12; p < 0.01), were extubated earlier (6.6 versus 14.2 days; p < 0.02) and required less time on supplemental oxygen (4.2 versus 12.5 days; p < 0.02). Pulmonary complications tended to be lower in the dexamethasone group (1/14 versus 4/12), as was the frequency of retinopathy (2/14 versus 6/12; p < 0.05). We conclude that early postnatal dexamethasone therapy improves response to surfactant therapy resulting in better weaning and earlier extubation in premature infants.

Anti-Inflammatory Agents↗

PubMed1995

Neonatal neutropenia in low birthweight premature infants.

Neutropenia, as defined by common reference values, occurs often in neonates. Its incidence, causes, and clinical consequences have not been studied extensively in premature neonates. Of 208 consecutive infants with birthweight up to 2000 g, 121 (58%) had neutropenia. Low gestational age and low birthweight correlated with the incidence of neutropenia. Less than half of the neutropenic episodes could be attributed to infections, the others were related to specific perinatal events and due to drug therapy or were of unknown cause. Neutropenia following treatment with certain antibiotics was the most common cause of neutropenia occurring after the second week of life. The high incidence of neutropenia in premature neonates raises questions about application of these reference ranges to low birthweight infants and suggests the need for new reference values.

Anti-Bacterial Agents↗

PubMed1995

Prognosis and outcome of neonates treated either with veno-arterial (VA) or veno-venous (VV) ECMO.

A comparison was done between neonates requiring veno-arterial (VA) ECMO (too small jugular vein, inability to insert a 12 Fr double lumen catheter or cardio-circulatory instability) and neonates treated with veno-venous (VV) ECMO in the same period of time. From 1991-1995 ECMO was done in 48 neonates after failure of maximum conventional treatments, NO-inhalation and HFOV. 30/48 babies were treated with VV-ECMO, with a switch to VA-ECMO later on in 3 of them. In 18 infants VA-ECMO was installed primarily. Differences between the VA- and VV-ECMO group were: the OI was higher in the VV-treated babies (62 +/- 20 vs. 48 +/- 13, p < 0.03), as were birth weight (3385 +/- 570 vs. 2963 +/- 653 g, p < 0.04), gestational age (39.7 +/- 1.6 vs. 37.9 +/- 2.7 weeks, p < 0.01) and MAP (18.7 +/- 2.2 vs. 17.1 +/- 2.4 cm H2O, p < 0.05). Severe ICH's occurred more frequently in the VA-treated babies (29 vs. 7%, p < 0.05), the rate of other complications was equal. The mortality rates were 43% (VA) and 15% (VV), p < 0.05. About one third of neonatal ECMO candidates will be treated with VA-ECMO, even if the VV-ECMO technique is available. Need for VA-ECMO implies--due to a higher number of preterm babies and a greater severity of illness before ECMO--a higher incidence of ICH's and a higher mortality rate.

Birth Weight↗

PubMed1995

High-frequency oscillatory ventilation and nitric oxide: alternative or complementary to ECMO.

One hundred and seventy-seven term or near-term neonates were referred to an ECMO center for severe PPHN-associated diseases. In 2 time periods from 1987 to 1991 and from 1992 to April 1995 alternative treatment modes were tried in an attempt to obviate ECMO. During the first time period patients underwent trial high-frequency oscillatory ventilation before ECMO. In the second time period patients first received inhaled NO followed by HFOV in a non-responders. If this also failed HFOV was combined with INO. In both time periods about 40% of the patients were spared ECMO treatment by these alternative treatment modalities. INO only benefited 15% of the ECMO candidates who apparently had fared just as well on HFOV alone in the preceding time period. While patients who were improved by INO were spared HFOV with its potential severe complications, i.e. air leaks and cardiocirculatory instability, more extended long-term studies will have to show which of these 2 treatment modalities (INO or HFOV) should be given first priority in an attempt to avoid ECMO in neonates with severe respiratory failure.

Administration, Inhalation↗

PubMed1993

Serum concentrations of granulocyte colony-stimulating factor in healthy term and preterm neonates and in those with various diseases including bacterial infections.

The neonate is uniquely susceptible to severe and overwhelming bacterial infections. One of the most important deficits in the neonatal host defense system seems to be a quantitative and qualitative deficiency of the myeloid and the phagocytic system. Future optimal therapy of neonatal sepsis may include the use of adjuvant immunologic therapy. Granulocyte colony-stimulating factor (G-CSF) has been shown to induce neutrophilia and to enhance mature effector neutrophil function. To evaluate the role of G-CSF with respect to infection, we examined serum levels of G-CSF in term and preterm neonates, using an enzyme-linked immunosorbent assay method. G-CSF levels in healthy neonates showed peak levels up to 7 hours after birth, followed by an increase in total neutrophil cell (TNC) counts. Both G-CSF levels determined between 4 and 7 hours after birth and peak TNC counts correlated with the gestational age of the neonates. The state of nutrition, maternal treatment with glucocorticoids, maternal infection and hypertension, and the mode of delivery influenced peak G-CSF levels. Neonates with signs of infection between 4 and 7 hours after birth had higher levels of G-CSF than did healthy neonates (1,312 +/- 396 pg/mL v 176 +/- 19 pg/mL). In conclusion, the presented results of serum concentrations of G-CSF in relation to TNC counts and various diseases suggests an important role of G-CSF in the regulation of granulopoiesis during the neonatal period.

Bacterial Infections↗

PubMed1993

[Extracorporeal membrane oxygenation (ECMO) in acute cardiovascular failure caused by myocarditis].

Main indication for extracorporeal membrane oxygenation (ECMO) is respiratory failure in the newborn. Less frequently ECMO is used for cardiac support. We report on a 4 months old boy, who suddenly fell ill with an acute viral myocarditis and heart failure (left-ventricular shortening fraction lowered to 17%). After failure of conventional management and resuscitation (twice) due to asystolic, veno-arterial ECMO was installed for a total time of 4 days. Under ECMO there was complete recovery of left-ventricular function; the infant was discharged 1 month after admission to hospital. ECMO-therapy should not only be considered in children with respiratory failure, but also in those with potentially reversible cardiac failure.

Echocardiography↗

PubMed1992

High frequency oscillatory ventilation and extracorporeal membrane oxygenation in severe persistent pulmonary hypertension of the newborn.

We report on 50 term and near-term neonates (birth weight greater than 1800 g, gestational age greater than 33 weeks) with severe persistent pulmonary hypertension of the newborn (PPHN), referred to us from January 1987 to July 1991 after failure of maximum conventional treatment. All infants had paO2 less than 45 mm Hg when ventilated with peak inspiratory pressure greater than 38 cm H2O and FiO2 = 1.0, hence meeting entry criteria for extracorporeal membrane oxygenation (ECMO). High frequency oscillatory ventilation (HFOV) was tried in all patients. If sufficient oxygenation could not be achieved (paO2 less than 40 mm Hg for at least 2 h), ECMO therapy was begun, which was the case in 25 children. Neonates responding to HFOV (n = 25) were of a slightly younger gestational age (37.0 weeks vs 38.8 weeks, P less than 0.05), had higher Apgar scores and were less hypoxaemic before HFOV (paO2 36.6 mm Hg vs 28.8 mm Hg, P less than 0.01); during HFOV there was a significant rise in paO2 (greater than 150 mm Hg; P less than 0.001) and a fall in pCO2 to 21.6 mm Hg (P less than 0.001). Due to air leaks, which was the main complication of HFOV (52%), ECMO therapy had to be begun in two additional infants after an initial positive effect. HFOV tended to be successful in cases of primary PPHN, meconium aspiration and sepsis, but not in infants with lung hypoplasia as a result of diaphragmatic hernia or other reasons. Success or failure of HFOV could not be reliably predicted by any parameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Gas Analysis↗

PubMed1992

High-dose intravenous immune globulin therapy for hyperbilirubinemia caused by Rh hemolytic disease.

We conducted a multicenter controlled trial to test the hypothesis that high-dose intravenous immune globulin (HDivIG) therapy can modulate bilirubin production and reduce the frequency of exchange transfusions in newborn infants with Rh hemolytic disease. Thirty-four patients with Rh incompatibility proved by positive direct antiglobulin test (Coombs test) results were randomly assigned to receive conventional treatment including phototherapy, with or without additional HDivIG therapy at 500 mg/kg given for a 2-hour period as soon as the diagnosis was established. Exchange transfusions were performed if serum bilirubin concentrations exceeded the modified curves of Polácek by more than 2 mg/dl. Two patients were excluded because of protocol violations. The results in 32 infants were analyzed. In the HDivIG group, 2 (12.5%) of 16 children required exchange transfusions, whereas it became necessary in 11 (69%) of 16 children in the control group (p less than 0.005). Bilirubin levels in the HDivIG group were lower despite reduced frequency of exchange transfusions. No side effects of HDivIG treatment were observed. We conclude that HDivIG therapy by a yet unknown mechanism reduces serum bilirubin levels and the need for blood exchange transfusions in children with Rh hemolytic disease.

Anemia↗

PubMed1992

[Fetal outcome of premature infants less than 1,500 g birth weight with special reference to surfactant requirements].

The objective of our study was to examine therapeutic success within a study group of 108 premature babies weighing less than 1500 g at birth. The foetal outcome was divided according to intrauterine betamethasone administration, method of birth and surfactant requirement. 59 of the babies did not require a surfactant factor, because within 12 hours it was possible, to reduce respiration to an O2 partial pressure of 20%. In 49 of the premature babies, this was not possible, and therefore, surfactant substitution was required, whereby this subject group was divided into surfactant responders and surfactant non-responders. In addition, we examined the influence of the method of birth on later survival and the occurrence of intraventricular haemorrhages in the children. A noticeably higher survival rate was determined in 81% of the children, born via Caesarean section, compared with 63% of premature babies, born via vaginal delivery. Likewise, detectable intraventricular haemorrhages (IVH) were significantly lower amongst premature babies delivered via Caesarean section (25%) than those delivered vaginally (37.5%). A considerable improvement in survival rates and a reduction in IVH was achieved by means of completed lung maturation with betamethasone (16 mg in 48 hours). 62% of premature infants with completed prepartal lung maturity did not require the administration of a surfactant due to the favourable respiratory situation. However, for those cases, where it was no longer possible to conduct lung maturation, only 46% did not require surfactant substitution. Therefore, it would appear advisable, to delay the delivery of premature babies weighing less than 1500 g in order to carry out lung maturity treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗

PubMed1992

Reconstruction of the arteria carotis communis in newborn following extracorporeal membrane oxygenation (ECMO).

With the help of ECMO it is possible to save the lives of newborn infants suffering from severe respiratory distress syndrome not responding to conservative treatment. Using Bartlett's classic venous-arterial perfusion technique in ECMO the right arteria carotis communis had to be sacrificed. Thus, despite the life-saving character of this new method, the ligation of the carotid with all its possible complications had often been a major argument against using this therapy. We are now therefore trying to reconstruct the arteria carotis after decannulating the vessel after extracorporeal membrane oxygenation. In our 8 cases so far, post-op examinations showed no obstruction of blood flow in the vessel. No neurological deficiencies were recorded.

Anastomosis, Surgical↗