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Biomedical subjects

D Lehmann

Publications and source records attributed to D Lehmann.

At least 127 records · Page 7Linked to original sources
PubMed1992

[Antimicrobial chemotherapy of infection in intensive care conditions].

Antimicrobiologic chemotherapy is a cornerstone in the modern concept of treatment of sepsis. It is supported by a number of measures of intensive care. Externally acquired infections followed by sepsis mainly affect immunocompromised patients. They represent the minority. On the other hand, nosocomial infections play a dominant role in intensive care units. Nosocomial pneumonias and infections caused by intravascular plastics or endoprotheses are the most important reasons of sepsis. Initial antimicrobiologic therapy considers both the infectious focus and the specific epidemiology and resistance of microorganisms present in the department: it comprises the drawing of 2 to 3 blood cultures, taking of urinary cultures, tracheal secretion, liquor and wound-swaps for microbiologic examination. A gramstaining of the preparation can be helpful. In case the focus of the sepsis is not known, the first step of treatment consists of a combination of piperacilline or cephalosporins with aminoglycosides. If the septic state does not improve within 48 hours, a glycopeptide should be added against staphylococci (second step). If the combination fails, imipenem/cilastatin and aminoglycosides are administered as the third step. Normally, the result of cultures and resistogram already are available by this time. Today aminoglycosides are preferably given once daily, the serum level is monitored, and the toxicity of aminoglycosides is thus diminished.

Anti-Bacterial Agents↗
PubMed1992

[Evaluation of evoked potential or event-related potential mapping].

Strategies for the evaluation of EP and ERP maps are discussed. Spatial interpolation is presented. The reference does not change the landscape but the wave shapes, the baselines change the landscape but not the wave shapes. Electric strength of the map is assessed using Global Field Power, whereby non-ambivalent component latencies can be established. Map landscapes are compared using Global Dissimilarity. Maps are classified using extracted landscape descriptors: locations of minimal and maximal potential, locations of the centroids of the positive and negative map area, reduction to a three-dimensional model dipole source. Adaptive segmentation into echoes of stable landscape (functional microstates) based on landscape descriptors is discussed. Diagnostic and physiological-functional interpretation of the results ought to be distinguished.

Brain Mapping↗
PubMed1991

Restricted T-cell receptor V beta gene usage by myelin basic protein-specific T-cell clones in multiple sclerosis: predominant genes vary in individuals.

Recent studies in experimental autoimmune encephalomyelitis as a model for multiple sclerosis (MS) have demonstrated limited heterogeneity in T-cell antigen receptors (TCR) specific for myelin basic protein (MBP). To investigate restricted beta-chain variable-region (V beta) gene usage in humans, we analyzed TCR gene rearrangements in two lines and 34 MBP-specific T-cell clones that were isolated from five MS patients and two healthy subjects. The T cells were characterized for their specificity to MBP epitopes and HLA-restricting molecules. We demonstrate here that MBP-specific T-cell clones from these different MS patients and healthy individuals, in contrast to T cells from rodents, display a more diverse V beta gene usage as evidenced by their TCR V beta gene rearrangements. However, the different MBP-specific T-cell clones isolated from each individual MS patient showed a common V beta gene usage, suggesting individual-specific TCR restriction. Out of 16 MBP-specific clones derived from a single MS patient, 12 clones (75%) utilized the V beta 15 gene for their TCR gene rearrangement. MBP-specific clones isolated from four other MS patients also showed a consistent tendency for a predominant, but different, TCR V beta gene rearrangement. These results suggest a TCR heterogeneity among MBP-specific T-cell clones from different individuals but a limited TCR V beta gene usage among MBP-specific T-cell clones of the same individual. The predominant V beta gene used by the MBP-specific T-cell clones studied here was not found to correlate with the epitope specificity of T cells or with their restricting HLA molecule. These findings may support the possibility of intervention with monoclonal antibodies to specific V beta gene products as an approach to immune therapy of MS but also imply the necessity for an individual-specific immunotherapeutic approach.

Base Sequence↗
PubMed1991

Event-related potential components N1, P2 and P3 to rare and frequent stimuli in intellectually impaired neurological patients.

Event-related potentials (ERPs) and attention performance data were collected in an auditory odd-ball paradigm from 24 intellectually impaired neurological patients, and compared with normal controls (n = 19). For the ERP components N1, P2 and P3, reference-independent measures (latency, global field power, current density at Cz, location of extreme potential, centroid location) were determined for the target stimulus and for the preceding and the following two "frequent" stimuli. In 8 of the 45 measures obtained, patients and controls differed significantly. To target stimuli, patients had shorter N1 latency and smaller current density, more posterior P2 location and longer P3 latency; to immediately following "frequent" stimuli, longer P2 latency; and to preceding and both following "frequent" stimuli, smaller P2 current density. Attention performance was significantly worse for the 15 patients who scored on at least one of the eight ERP measures above normal range than for the other 9 patients. Decreased N1 latency to targets is viewed as failure to activate normal attentional capacity; changed P2 location suggests activation of deviant neuronal populations in response to targets; and increased post-target P2 latency suggests abnormal persistence of induced state change.

Adult↗
PubMed1991

Effect of pneumococcal vaccine on morbidity from acute lower respiratory tract infections in Papua New Guinean children.

The effect of a 14-valent pneumococcal polysaccharide vaccine on morbidity from acute lower respiratory tract infection (ALRI) was determined in a randomized double-blind controlled trial in children under the age of 5 years living in the Paupa New Guinea highlands. The vaccine did not protect against mild ALRI. Vaccine efficacy in the study as a whole was 28% for moderate/severe ALRI, which was not statistically significant though consistent with the significant effect on mortality. Children entered the trial in five separate cohorts 4 months apart. The incidence of disease and vaccine efficacy varied between cohorts and with age. There was no vaccine effect in the first cohort, which had a much higher proportion of older children. The effect was greatest and statistically significant among those groups encountering an epidemic of moderate and severe ALRI at a young age. It was therefore in children at the most vulnerable age in times of greatest incidence of disease that the vaccine had its most potent effect. It is postulated that the efficacy of pneumococcal vaccine is dependent on the predominant invading serotypes in the period after vaccination, the age at which children develop immunocompetence to specific vaccine serotypes, and the levels of naturally acquired specific immunity already present in children at the time of vaccination, and that for all of these conditions there will be a cohort effect.

Acute Disease↗
PubMed1991

Relationships between growth and acute lower-respiratory infections in children aged less than 5 y in a highland population of Papua New Guinea.

One hundred fifty-six children in the highlands of Papua New Guinea aged less than 5 y, studied for a total of 7019 child-weeks, had an incidence of 1.3 episodes per child-year of acute lower-respiratory-tract infections (ALRIs). There was a marked age trend with an incidence of almost three times this average for children aged less than 6 mo. Those with low weight-for-age or low height-for-age had a higher ALRI incidence rate, with no evidence of cutoffs above which nutritional status had no effect; there was no association between low weight-for-height and increased risk of ALRI. A slow weight gain was not a significant risk factor in the short term but weight gain was reduced during episodes of ALRI.

Aging↗
PubMed1991

Antibodies to pneumococcal polysaccharides in pneumonia and response to pneumococcal vaccination in young children in Papua New Guinea.

Antibodies against pneumococcal polysaccharides were measured by ELISA in Papua New Guinean children with pneumonia aged 0-14 months, in age-matched healthy Papua New Guinean controls and in healthy expatriate children living in Papua New Guinea. At 0-5 months of age, the IgG antibody titres against six of the eight polysaccharides measured were significantly lower in pneumonia patients than in both control groups. Antibody titres in 6-14-month-old Papua New Guinean controls were significantly lower than in control Papua New Guineans aged 0-5 months for five of the eight polysaccharides tested. In the 6-14-months age group the antibody titre was significantly lower in pneumonia patients than in controls for only one polysaccharide. For seven of the eight serotypes tested, antibody levels in expatriate controls did not decline with age. Antibody responses of Papua New Guinean children aged 6-18 months to a 23-valent pneumococcal vaccine were serotype dependent. Fold increases in response to the vaccine were greatest for the IgA isotype. IgG antibody responses were greater than three fold to four of the eight serotypes tested.

Age Factors↗
PubMed1991

Amikacin pharmacokinetics in patients receiving high-dose cancer chemotherapy.

We retrospectively analyzed amikacin pharmacokinetics in 28 patients (mean age, 47.4 +/- 13.6 years) who received high-dose chemotherapy during a neutropenic febrile episode. Patients received an experimental protocol of high-dose anticancer chemotherapy. Amikacin pharmacokinetic parameters were calculated from two or more concentrations in serum around a single dose by the method of Sawchuck and Zaske (J. Pharmacokinet. Biopharm. 4:183-195, 1976). Predicted parameters were calculated by using standard methods. The observed amikacin volume of distribution and clearance were significantly greater and the elimination half-life was longer than predicted (0.38 +/- 0.13 versus 0.25 liter/kg [P = 0.0001], 1.51 +/- 0.92 versus 1.17 +/- 0.38 liters/h/kg [P = 0.012], and 3.8 +/- 2.4 versus 2.9 +/- 1.1 h [P = 0.011], respectively). Multivariate analysis revealed that albumin correlated negatively and creatinine correlated positively with the volume of distribution and the elimination half-life. Creatinine and the percentage below the ideal body weight correlated negatively and hematocrit correlated positively with clearance. Administration of dosage regimens based on predicted pharmacokinetic parameters yielded subtherapeutic amikacin concentrations in serum in our patients. Because of the increased dosage requirements and the need for adequate antibiotic treatment in this population, we suggest guidelines for empiric dosing for patients with advanced cancer receiving intensive chemotherapy.

Adolescent↗
PubMed1991

Reduction in the incidence of acute bronchitis by an oral Haemophilus influenzae vaccine in patients with chronic bronchitis in the highlands of Papua New Guinea.

Following the administration of a standardized questionnaire, 62 adult patients with chronic bronchitis were enrolled into a double-blind controlled trial of an oral killed Haemophilus influenzae vaccine in the highlands of Papua New Guinea. A 3-day course of vaccine or placebo was given monthly for 3 consecutive months. Participants were monitored weekly over 12 months for acute exacerbations; early morning sputum specimens were collected monthly and during acute exacerbations. Density of colonization by H. influenzae and H. parainfluenzae was determined by standard quantitative and semiquantitative techniques, and the latter method (quadrant score) was used to determine the density of growth of pneumococci. A total of 30 patients received vaccine and 32 placebo. The incidence rate of acute bronchitis in the vaccine group (0.011 episodes/person-weeks) was significantly lower than that in the placebo group (0.021 episodes/person-weeks), but there was no difference between the two groups in the incidence rates of more severe disease. Vaccine efficacy was maximal at times of peak incidence of disease. There was no evidence of a decline in vaccine efficacy for acute bronchitis over the 12-month follow-up period. The number of viable H. influenzae in the sputum declined in both vaccine and placebo groups over the 12-month follow-up period. The average concentration of H. influenzae in the vaccine group fell below that in the placebo group within 1 to 2 months after first immunization and remained so for 12 months, although the difference between the two groups narrowed during the follow-up period.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

Mortality and morbidity from acute lower respiratory tract infections in Tari, Southern Highlands Province 1977-1983.

Monthly demographic surveillance by village reporters has been ongoing in the Tari Basin since 1970. Cause of death is ascertained by verbal autopsy. 20% of deaths between 1977 and 1983 were from acute lower respiratory tract infection (ALRI). ALRI mortality rates were highest in the very young and the elderly and have risen since the early 1970s but declined in the 1981-1983 period when pneumococcal vaccine was being tested in Tari. 44% of ALRI deaths in children under 5 years of age occurred before the age of 6 months but ALRI mortality remained high during the second year of life. Utilization of health services before death was highly age-dependent, with the vast majority of young children but few elderly people receiving some form of medical attention. However, less than half the children who died of ALRI received inpatient care. Fortnightly morbidity surveillance of children between 1981 and 1983 showed that ALRI was the commonest cause of severe morbidity; children suffered 2-3 episodes of ALRI in the first year of life, 20% of which were moderate or severe disease. Improved case management, nutritional status and hygiene in addition to good coverage with pertussis and measles vaccines and immunization with efficacious pneumococcal and H. influenzae vaccines are required to reduce mortality and morbidity from ALRI.

Acute Disease↗
PubMed1990

Impact of active immunisation against enteritis necroticans in Papua New Guinea.

Enteritis necroticans, known locally as pigbel, has been a major cause of illness and death among children in the highlands of Papua New Guinea. After a successful trial of active immunisation against the beta toxin of the causative organism, Clostridium perfringens type C, immunisation of children was begun in 1980. The effects of the immunisation programme on pigbel admissions in 3 of the 5 major highland hospitals were assessed. In each of the centres studied the proportion of admissions due to enteritis necroticans dropped significantly after immunisation was introduced (p less than 0.001) and hospital admissions for pigbel in 1984-86, when immunisation was well established, were less than one fifth of previous figures.

Adolescent↗
PubMed1990

Past, present and future of topographic mapping.

Traditional EEG and EP analysis is trace-oriented. When mapping became popular, results of waveform analysis were mapped. Increased exposure to brain field maps has begun to orient analysis to the spatial aspects. Different maps must be generated by different neuronal populations; this offers direct key to the analysis of higher brain function. Space-oriented data reduction selects maps with optimal signal/noise ratio using Global Dissimilarity index. Classification and statistics of map landscapes uses extracted descriptors (locations of extrema or centroids) or three-dimensional dipole models. Map classification leads to adaptive segmentation of evoked or spontaneous map series into functional micro-states, the putative building blocks of perception and cognition.

Brain↗
PubMed1990

Intracerebral dipole source localization for FFT power maps.

The method treats Fast Fourier Transforms (FFTs) of multichannel EEGs so that they can be used for intracerebral source localizations. For each frequency point, the FFT results are entered into a sine-cosine diagram. Into the diagram's entry constellation (FFT constellation), a straight line (single dipole model) is fitted which produces the least square deviation sum between the entry positions and their orthogonal projections onto the straight line. The map described by the voltages between the projected positions on the straight line is the single source 'FFT approximation' of the FFT constellation. The FFT approximation map is used for dipole source localization. The squared FFT approximation map and the squared map of the forward solution of the computed dipole (power maps) closely resemble the original power map.

Adult↗
PubMed1990

N1 and P2 of frequent and rare event-related potentials show effects and after-effects of the attended target in the oddball-paradigm.

The effects of serial order of the stimuli on event-related potentials (ERPs) in an auditory oddball paradigm with 700 ms ISI were studied in 19 normals, recording from Fz, Cz, Pz and combined ears. N1 and P2 to the last preceding frequent stimulus, the rare (attended target) stimulus, and the following two frequent stimuli were evaluated using 6 reference-independent measures: latency (time of maximal potential range between any two locations), amplitude of maximal potential range, global field power, vertex (Cz) current source density, location of extreme potential, and location of potential centroid. Exploratory statistics were used to determine differences of interest. Eighteen of the 36 comparisons for N1, and 4 of the 36 comparisons for P2 showed double-ended P-values of less than 5%, 6 times the overall incidence expected by chance. For the ERP evoked 1400-ms post-target, global field power and location of N1, and latency and location of P2 still differed from pre-target ERP values. This suggests a new and temporarily persisting change of brain state following the target stimulus. The first 3 measures showed 'undershoot' below pre-target levels, contradicting a simple 're-habituation' model. All 6 measures of N1, as well as latency and location of P2 increased or anteriorized for the attended target; the location changes indicate that processing the attended target activates additional neural processes, and does not only increase the activation of the same neural processes which operate on frequent stimuli.

Acoustic Stimulation↗
PubMed1990

Viruses associated with acute lower respiratory tract infections in children from the eastern highlands of Papua New Guinea (1983-1985).

This study, conducted at Goroka Hospital from January 1983 to June 1985, examined the viruses identified in nasopharyngeal aspirates (NPA) and urines collected from 716 hospitalised children with moderate or severe pneumonia, in NPA from 170 children with mild pneumonia treated as outpatients and in NPA from a control group of 428 children attending the outpatient department of Goroka Hospital suffering from minor ailments other than upper or lower respiratory tract infections. One or more viruses were identified from 68%, 51% and 43% of children with moderate or severe pneumonia, mild pneumonia and the control group, respectively. One-third of viruses were identified in conjunction with another virus in both control and sick children. Viral identification rates were highest in children under 1 year of age. Cytomegalovirus, adenoviruses, respiratory syncytial virus (RSV), measles and rhinoviruses were the most frequently identified viruses. RSV was associated with mild as well as moderate and severe disease. No virus was associated with an increased risk of death. Annual epidemics of RSV occurred during the wet season. An epidemic of influenza A virus and also influenza B virus and 3 epidemics of parainfluenza 3 virus occurred during the study period. The high viral identification rates in this study suggest a high frequency of transmission associated with the social structure and environment of Papua New Guinean highland villages and high population mobility.

Acute Disease↗
PubMed1990

[A universal verification and protocol system for teletherapy].

To increase the quality of radiotherapy a verify and record system (VPS) was developed for teletherapy equipments, that takes control of manually adjusted irradiation parameters and of recording all relevant data of radiotherapy. The VPS can be adapted to special wishes of the user and it lends itself to application on different irradiation equipments. In the represented paper especially the extent of efficiency of the system is shown which is characterized by high operating comfort, flexible reacting to exceptional cases and by high date and operating security. The testing phase on an accelerator model has been brought to a close, actually the system is installed to an electron linear accelerator "Neptun 10p" and led to clinical trial.

Humans↗