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K Weiss

Publications and source records attributed to K Weiss.

At least 37 records · Page 2Linked to original sources
PubMed2001

A simple method for SC-cut resonator design.

This paper presents a design method utilizing simple semi-empirical equations for round, plano-convex SC-cut resonators. These equations were developed on the basis of experimental results collected over a long period relating SC-cut resonator design and performance covering a wide range of frequencies, radii of curvature, and plate diameters. The equations make possible the design of fundamental, third overtone, and fifth overtone resonators. An example calculation of resonator parameters and comparison with experimental results are also presented.

Journal Article↗
PubMed2001

Developmental screening of children diagnosed with congenital heart defects.

Children with congenital heart disease (CHD) are more likely than normal children to have developmental delays. The development of 64 children with CHD less than 6 years old was screened with the Denver II. Thirty-five of the 64 children had CHD that required surgical or catheter intervention. These 35 children were significantly less likely than other children with CHD to be normal on developmental screening (46% vs 86%, respectively). Thirty-four percent of children with more severe CHD were referred for early intervention. As research shows the efficacy of early intervention, results indicate the need for early developmental evaluation of children with CHD of hemodynamic significance.

Analysis of Variance↗
PubMed2000

Expression of Dlx genes during the development of the murine dentition.

The mammalian Dlx homeobox gene family has been shown to play multiple roles in tooth development, but a detailed comparison of the expression pattern of all members throughout tooth development has been lacking. We provide such an analysis for the six known murine Dlx genes. The expression patterns for these genes allow a refinement of previously proposed models for the role of Dlx genes in tooth type specification and raise the possibility of roles for subsets of these genes in tooth initiation, morphogenesis (enamel navel formation, enamel knot induction, cervical loop growth), and enamel formation. The relationship of Dlx gene expression to their genomic organization suggests coordinate regulation of linked genes at early stages but regulatory differences at later stages.

Animals↗
PubMed2000

Comparative evaluation of the MB/BacT and BACTEC 460 TB systems for the detection of mycobacteria from clinical specimens: clinical relevance of higher recovery rates from broth-based detection systems.

New broth-based detection systems have higher recovery rates of mycobacteria from clinical specimens than traditional cultures on solid media. The clinical significance of this higher sensitivity rate is largely unknown. We prospectively evaluated the performances of two liquid media detection systems (the MB/BacT system and the BACTEC 460 TB system) and an egg-based Lowenstein-Gruft solid medium (LG) on the recovery rates of mycobacteria from 849 clinical specimens. Mycobacteria (other then M. gordonae) were detected in 51 (6.0%) specimens. In 12/51 (23%) specimens, mycobacteria (five mycobacterium tuberculosis (MtB) and seven non-M tuberculosis complex (MOTT) were recovered only from the broth-based systems. Review of the patients' clinical charts revealed that failure of LG to recover Mtb were due to nonmycobacterial overgrowth and antibiotic treatment. The recovered MOTT were all clinically nonsignificant. Higher sensitivity of broth-based mycobacteria detection systems is largely due to their capability to recover mycobacteria from treated tuberculous patients or from partially decontaminated specimens. The high recovery rates of nonclinically significant MOTT could potentially increase inappropriate use of antibiotics.

Bacterial Typing Techniques↗
PubMed2000

Peripherally administered antibodies against amyloid beta-peptide enter the central nervous system and reduce pathology in a mouse model of Alzheimer disease.

One hallmark of Alzheimer disease is the accumulation of amyloid beta-peptide in the brain and its deposition as plaques. Mice transgenic for an amyloid beta precursor protein (APP) mini-gene driven by a platelet-derived (PD) growth factor promoter (PDAPP mice), which overexpress one of the disease-linked mutant forms of the human amyloid precursor protein, show many of the pathological features of Alzheimer disease, including extensive deposition of extracellular amyloid plaques, astrocytosis and neuritic dystrophy. Active immunization of PDAPP mice with human amyloid beta-peptide reduces plaque burden and its associated pathologies. Several hypotheses have been proposed regarding the mechanism of this response. Here we report that peripheral administration of antibodies against amyloid beta-peptide, was sufficient to reduce amyloid burden. Despite their relatively modest serum levels, the passively administered antibodies were able to enter the central nervous system, decorate plaques and induce clearance of preexisting amyloid. When examined in an ex vivo assay with sections of PDAPP or Alzheimer disease brain tissue, antibodies against amyloid beta-peptide triggered microglial cells to clear plaques through Fc receptor-mediated phagocytosis and subsequent peptide degradation. These results indicate that antibodies can cross the blood-brain barrier to act directly in the central nervous system and should be considered as a therapeutic approach for the treatment of Alzheimer disease and other neurological disorders.

Alzheimer Disease↗
PubMed2000

Genetic enhancement of fracture repair: healing of an experimental segmental defect by adenoviral transfer of the BMP-2 gene.

This study evaluated the ability of gene transfer to enhance bone healing. Segmental defects were created surgically in the femora of New Zealand white rabbits. First generation adenoviruses were used as vectors to introduce into the defects genes encoding either human bone morphogenetic protein-2 (BMP-2) or, as a negative control, firefly luciferase. Representative specimens were evaluated histologically after 8 weeks. Healing of the defects was monitored radiographically for 12 weeks, after which time the repair tissue was evaluated biomechanically. By radiological criteria, animals receiving the BMP-2 gene had healed their osseous lesions after 7 weeks, whereas those receiving the luciferase gene had not. Histologic examination of representative rabbits at 8 weeks confirmed ossification across the entire defect in response to the BMP-2 gene, whereas the control defect was predominantly fibrotic and sparsely ossified. At the end of the 12-week experiment, the control femora still showed no radiological signs of stable healing. The difference in radiologically defined healing between the experimental and control groups was statistically significant (P < 0. 002). Biomechanical testing of the femora at 12 weeks demonstrated statistically significant increases in the mean bending strength (P < 0.005) and bending stiffness (P < 0.05) of the animals treated with the BMP-2 gene. Direct, local adenoviral delivery of an osteogenic gene thus led to the healing of an osseous lesion that otherwise would not do so. These promising data encourage the further development of genetic approaches to enhancing bone healing. Gene Therapy (2000) 7, 734-739.

Adenoviridae↗
PubMed2000

Comparative activity of new quinolones against 326 clinical isolates of Stenotrophomonas maltophilia.

Stenotrophomonas maltophilia is an important emerging pathogen causing a variety of infections in severely ill patients. This microorganism is inherently resistant to many antibiotics, and only a few therapeutic options are available. The principal aim of this study was to assess the in vitro activity of new quinolones against this pathogen. Three hundred and twenty-six single clinical isolates were tested in this study. The MIC(90) was 16 mg/L for ciprofloxacin, 8 mg/L for levofloxacin and gatifloxacin, 4 mg/L for trovafloxacin, moxifloxacin and sparfloxacin and 2 mg/L for clinafloxacin. At a 2 mg/L concentration, a C(max) lung:MIC ratio of >/=10 can be reached for 95%, 84.3%, 83.1% and 81.5% of isolates, respectively, for clinafloxacin, trovafloxacin, moxifloxacin and sparfloxacin (P < 0. 001 compared with levofloxacin and ciprofloxacin). In spite of the rare but serious adverse events associated with the new-generation quinolones, these agents may become very useful in the treatment of certain severe or life-threatening infectious conditions due to S. maltophilia, notably lower respiratory tract infections.

4-Quinolones↗
PubMed2000

Antarctica natural laboratory and space analogue for psychological research.

This introduction to the special issue traces the history of psychosocial concerns related to Antarctic exploration, from the heroic age of early explorers through the International Geophysical Year (IGY) of 1957 to 1958 to recent and current systematic research projects. The introduction discusses the organization and topics of international psychological investigations in polar stations and summarizes the articles that follow. Living in Antarctica imposes some unusual restrictions as well as opportunities, and it requires psychological adaptation to extreme environmental circumstances. The thrust of previous scientific and popular literature has been to focus on the negative effects of the situation and ignore the positive ones; however, ongoing studies are bringing about a more balanced view. Having an accurate understanding is important not only intrinsically and for appropriate application in the Antarctic itself but also in analogous extreme and unusual environments. These include extended space flight and space habitation, such as the projected voyage to Mars.

Adaptation, Psychological↗
PubMed2000

Psychological adjustment during three Japanese Antarctic research expeditions.

This study investigates the individual characteristics of Japanese polar team members. Four sets of measures from the Polar Psychology Project Battery have been used in Asuka Station. These measures are thought to reflect adjustment and well-being. Data have been collected during 3 consecutive years. The psychological profile of the subjects was relatively stable, and comparable to the standard means of Western sojourners. The results show the subjects were generally high in stress resistance. However, an increase in the Planning Orientation score and a decrease in the Hardiness score appear at the end of the wintering-over. These modifications correspond to psychological changes linked to the approaching end of wintering-over.

Adaptation, Psychological↗
PubMed2000

Delivery room management of the apparently vigorous meconium-stained neonate: results of the multicenter, international collaborative trial.

OBJECTIVE: Disagreement exists concerning the appropriate delivery room management of the airway of vigorous meconium-stained infants. Some suggest a universal approach to intubation and suctioning of the airway in all such neonates, whereas others advocate a selective approach. We performed this investigation: 1) to assess whether intubation and suctioning of apparently vigorous, meconium-stained neonates would reduce the incidence of meconium aspiration syndrome (MAS); and 2) to determine the frequency of complications from delivery room intubation and suctioning of such infants. METHODS: Inclusion criteria included: 1) gestational age >/=37 weeks; 2) birth through meconium-stained amniotic fluid of any consistency; and 3) apparent vigor immediately after birth. Subjects were randomized to be intubated and suctioned (INT) or to expectant management (EXP). Primary outcome measures included: 1) the incidence of respiratory distress, including MAS, and 2) the incidence of complications from intubation. RESULTS: A total of 2094 neonates were enrolled from 12 participating centers (1051 INT and 1043 EXP). Meconium-stained amniotic fluid consistency was similar in both groups. Of the 149 (7.1%) infants that subsequently demonstrated respiratory distress, 62 (3.0%) had MAS and 87 (4.2%) had findings attributed to other disorders. There were no significant differences between groups in the occurrence of MAS (INT = 3.2%; EXP = 2.7%) or in the development of other respiratory disorders (INT = 3.8%; EXP = 4.5%). Of 1098 successfully intubated infants, 42 (3.8%) had a total of 51 complications of the procedure. In all cases, the complications were mild and transient in nature. CONCLUSIONS: Compared with expectant management, intubation and suctioning of the apparently vigorous meconium-stained infant does not result in a decreased incidence of MAS or other respiratory disorders. Complications of intubation are infrequent and short-lived.

Adult↗
PubMed2000

[Surgical procedures on the external carotid artery].

A clinical series of five patients operated on for symptomatic cerebral blood flow deterioration is discussed. They presented with either hemispheral symptoms (hemiparesis, amaurosis fugax) or signs of diffuse cerebral hypoxia. In the presence of unilateral or bilateral internal carotid artery (ICA) occlusion a critical stenosis of the external carotid artery (ECA) was confirmed either by duplex ultrasound or angiography. In all these cases ECA was reconstructed by means of common vascular surgical techniques. The use of intraluminal (i.l.) shunt was mandatory. There were neither early nor late deaths in this group. In one patient a transient stroke occurred three days following standard carotid endarterectomy performed after ECA surgery on the contralateral side. After the mean follow-up of 46 months all patients remain neurologically asymptomatic. In selected cases the ECA reconstruction offers an effective and beneficial tool for surgical management of critical cerebral perfusion impairment.

Adult↗
PubMed1999

Template-Mediated Synthesis of Polycyclic Aromatic Hydrocarbons: Cyclodehydrogenation and Planarization of a Hexaphenylbenzene Derivative at a Copper Surface.

The deposition of polycyclic aromatic hydrocarbons on substrate surfaces is a key step for using such disklike molecules in nanoelectronic devices. An alternative to the (frequently problematic) preparation by evaporation or deposition from solution is to use the substrate surface as a template for the planarization that accompanies the cyclodehydrogenation (see picture).

Journal Article↗
PubMed1999

Group A Streptococcus carriage among close contacts of patients with invasive infections.

During the past few years, the incidence of invasive group A Streptococcus (GAS) infection has been increasing. However, there are presently no clear recommendations regarding antibiotic prophylaxis for close contacts of index patients. The aims of this study were 1) to determine the prevalence of carriage of the same GAS strain as the patient's among contacts of patients with invasive infections and 2) to assess the importance of exposure duration. From March 1995 to March 1996, the authors prospectively included in the study all patients with invasive GAS infection, as defined by the Working Group on Severe Streptococcal Infections, who came to Hôpital Maisonneuve-Rosemont in Montreal, Quebec, Canada. An epidemiologic investigation was systematically carried out for each index case. Contacts were divided into two groups: those who had spent 24 hours or more with the index patient during the week preceding the beginning of his or her illness and those who had spent 12-24 hours with the index patient during that week. Strains of GAS were examined by serotyping (proteins M and T and the presence or absence of the serum opacity factor) and by characterization of streptococcal pyrogenic exotoxins (exotoxins A, B, and C). One hundred and two contacts of 17 index cases with invasive GAS infection were systematically screened. Contacts were considered positive if they carried the same strain of the bacterium and the same streptococcal pyrogenic exotoxin as the index case. Among the contacts who had spent at least 24 hours per week with their respective index cases, 13 out of 48 (27%) were found to be harboring the same serotype of GAS as the index patient (95% confidence interval 14.5-39.5). By comparison, only one of the 54 contacts in the 12- to 24-hour group (1.8%) was found to be carrying the same strain of the bacterium (95% confidence interval 0-5.3). This difference between the two groups was statistically significant (p<0.001). The median age of the positive carriers (10 years) was significantly lower than the median age of the noncarriers (39 years) (p< or =0.0005). This study showed that close contacts who had spent 12-24 hours with the index patient were rarely colonized with GAS. If antibiotic prophylaxis against GAS is recommended, it should probably target contacts who spent at least 24 hours with an infected patient during the week preceding illness onset.

Adolescent↗
PubMed1999

Adenoviral transfer of the viral IL-10 gene periarticularly to mouse paws suppresses development of collagen-induced arthritis in both injected and uninjected paws.

Gene therapy is a promising new approach in the treatment of rheumatoid arthritis. Gene delivery to diseased joints offers the prospect of achieving high, local concentrations of a therapeutic gene product in a sustained manner, while minimizing exposure of nontarget organs. We report that a single administration of a modified adenovirus encoding the Epstein-Barr-derived homologue of IL-10 can suppress the development of disease for extended periods of time when injected locally within the periarticular tissue surrounding the ankle joints of mice with collagen type II-induced arthritis. Furthermore, we show that injection of an adenoviral vector carrying the IL-10 gene into a single paw can suppress development of arthritis in other, noninjected paws of the same individual. The systemic protection resulting from local gene therapy occurred in the absence of detectable levels of viral IL-10 in the serum. Circulating Ab levels to heterologous collagen were unaffected; however, treatment with viral IL-10 significantly suppressed the development of Abs to autologous mouse type II collagen. Thus, the treatment of a single joint by local delivery of the vIL-10 gene may protect multiple joints of the same individual while avoiding deleterious side effects often associated with systemic therapy.

Adenoviridae↗
PubMed1999

[Investigations on the fermentation quality of silage from low-nitrate green forage].

In 3-year-experiments green forage from Dactylis glomerata and Festuca species, produced by differentiated cutting frequencies, was ensiled under laboratory conditions. The forage was almost without nitrate. Because of the higher content of water-soluble carbohydrates the fermentability coefficients of Festuca species were above of Dactylis glomerata. The fermentability coefficients of both plant species were inferior in the second and third cut, even if the first cut was delayed until July. Despite of similar fermentability coefficients of the two plant species silages contained different amounts of lactic and butyric acid. The portion of lactic acid amounted to 52 to 57% and 60 to 73% of total acids, the proportion of butyric acid 30 to 35% and 18 to 25% for Dactylis glomerata and Festuca species, respectively. According to the high fermentability coefficients silages free of butyric acid would be expected, however, by both species butyric acid always was formed, in some cases at high concentrations. In the contrary the amounts of ammonia, acetic acid and alcohol as well as the pH-value were almost extremely low. It can be concluded that the quality of silages produced of green forages with low nitrate cannot be assessed adequately by the current evaluation key.

Acetic Acid↗