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J Meyer

Publications and source records attributed to J Meyer.

At least 271 records · Page 15Linked to original sources
PubMed1998

Calculation of left ventricular outflow tract area using three-dimensional echocardiography. Influence on quantification of aortic valve stenosis.

In 23 patients with aortic valve stenosis (14 male, 9 female, mean age 66 +/- 21.5 years) left ventricular outflow tract cross-sectional area was determined in planimetric fashion using three-dimensional echocardiography. The 3-D data-set for each patient had been acquired in the course of a multiplane transesophageal examination. Aortic valve area was determined using the continuity equation. Results obtained were compared to those calculated by continuity equation using to the conventionally determined LVOT area (a = pi [d/2]2). As reference method the results were compared to invasive measurements. 3-D planimetric determination of LVOT cross-sectional area was possible in 20 of 23 patients. In three patients, this method failed due to artefacts. The mean difference to the conventionally calculated LVOT area amounted to 0.18 cm2 (SD = 0.46). The comparison of AVA determined by continuity equation and by invasive measurement showed a mean difference of -0.074 cm2 (SD = 0.21) for the conventionally calculated LVOT area; for the planimetrically determined LVOT area the mean difference of AVA amounted to -0.03 cm2 (SD = 0.14) (p < 0.05). Planimetric determination of LVOT area using 3-D echocardiography improves the agreement of the continuity equation with invasive measurement.

Aged↗
PubMed1998

Preclinical antitumor efficacy of analogs of XK469: sodium-(2-[4-(7-chloro-2-quinoxalinyloxy)phenoxy]propionate.

A series of quinoxaline analogs of the herbicide Assure was found to have selective cytotoxicity for solid tumors of mice in a disk-diffusion-soft-agar-colony-formation-assay compared to L1210 leukemia. Four agents without selective cytotoxicity and 14 agents with selective cytotoxicity were evaluated in vivo for activity against a solid tumor. The four agents without selective cytotoxicity in the disk-assay were inactive in vivo (T/C > 42%). Thirteen of the fourteen agents with selectivity in the disk-assay were active in vivo (T/C < 42%). Five of the agents had curative activity. These five agents had a halogen (F, Cl, Br) in the 7-position (whereas Assure had a CI in the 6 position). All agents with curative activity were either a carboxylic acid, or a derivative thereof, whereas Assure is the ethyl ester of the carboxylic acid. All other structural features were identical between Assure and the curative agents. Assure had no selective cytotoxicity for solid tumors in the disk-assay, and was devoid of antitumor activity. The analog XK469 is in clinical development.

Animals↗
PubMed1998

Bolus Administration of Saruplase in Europe (BASE), a Pilot Study in Patients with Acute Myocardial Infarction.

To study the safety and efficacy of the thrombolytic agent saruplase as a bolus, the angiographic and clinical outcomes of three bolus regimens were investigated in a pilot study conducted in 192 patients with an acute myocardial infarction and were compared with the standard regimen. Fifty-two patients received a double bolus of 40 mg and 40 mg after 30 minutes, 51 patients a bolus of 80 mg, and 36 patients a bolus of 60 mg. Fifty-three patients received the standard regimen (a bolus of 20 mg and 60 mg IV infusion over 1 hour). At 60 minutes TIMI 2 and 3 flow were, respectively, 9.6% and 61.5% with the 40/40-mg bolus, 15.7% and 51.0% with the 80-mg bolus, 16.7% and 30.6% with the 60-mg bolus, and 7.5% and 54.7% with the standard 20/60-mg infusion. At 90 minutes TIMI 2 and 3 flow improved to 9.6% and 73.1%, 15.7% and 56.9%, 13.9% and 36.1%, and 5.7% and 71.7%, respectively. The primary endpoint, persistent patency (TIMI 2 + 3) at 24-45 hours, was seen in 69.2%, 64.7%, 44.4%, and 67.9% of patients who had no rescue PTCA, respectively. Inclusion in the 60-mg bolus group was prematurely stopped because of their low patency rates. The 40/40-mg bolus group had the highest mortality rate (13.5%), whereas the 60-mg bolus group had no deaths. Other adverse event rates were similar in the four groups. This clinical outcome is highly influenced by rescue PTCA of patients with insufficient TIMI flow. This pilot study indicates that in patients with an acute myocardial infarction, a double bolus of 40/40 mg resulted in the highest patency but also had the highest complication rate. The 80-mg single bolus is an attractive alternative for further evaluation because of its acceptable patency and event profile, and its easy form of administration.

Journal Article↗
PubMed1998

Genetic "clocks" and "soft" events: a twin model for pubertal development and other recalled sequences of developmental milestones, transitions, or ages at onset.

We propose and explore a twin model to examine the basis for synchrony that often characterizes different facets of normal development. In so doing we also present an approach to the analysis of "soft" events; events for which available reports of dates or ages of occurrence are unreliable or inconsistent. Discrepancies among reports are accounted for by a statistical measurement model. This combines current status error reflecting uncertain definition of onset and two mechanisms for the phenomenon of "telescoping," namely, systematic compression of the time scale and heteroscedastic random measurement error. Statistically, the model can be viewed as a mixed generalized linear model with random effects within both mean and variance functions or, alternatively, as involving multiplicative random effects. We apply the model to multiple maternal reports on menarche and onset of breast development in twin daughters. Fitted to data from the Virginia Twin Study Of Adolescent and Behavioral Development by the use of penalized/predictive quasi-likelihood, the model provided much improved estimates of the true age-at-onset distribution as compared to those from a naive analysis. Results suggested that the observed variance was made up almost entirely of genetic variance and measurement error variance due to telescoping and current status errors and that the timing of breast development and menarche are largely under the control of a common set of genes. Results also indicated that maternal recollections of the onset of breast development were both more poorly defined and subject to greater recall errors than maternal recollections of menarche.

Adolescent↗
PubMed1998

Bacterial leakage into and from prefabricated screw-retained implant-borne crowns in vitro.

A mean gap of less than 4 microm following laboratory procedures and continuous loading was demonstrated in prefabricated crowns of the Ha-Ti implant system in earlier studies. The clinical relevance of such high precision in maintaining inflammation free marginal mucosa is yet to be determined. In this present investigation, the complete assembly of Ha-Ti implants including prefabricated screw-retained crowns was tested for bacterial leakage under controlled conditions in vitro. The gaps were shown not to be a barrier for Staphylococcus aureus which were used as test bacteria. Bacterial leakage through these gaps from the environment to the interior of the assembly and vice versa was observed within 24-120 h. The main path of bacterial penetration was possibly found to be through the transversal screw hole and not through the marginal gap of the prefabricated crowns.

Crowns↗
PubMed1998

Impact of restenosis 10 years after coronary angioplasty.

AIMS: The aim of the study was to compare the 10-year follow-up results of patients with or without restenosis following single-vessel percutaneous transluminal coronary angioplasty (PTCA). METHODS AND RESULTS: A total of 313 patients with successful PTCA (> or = 20% reduction in luminal diameter narrowing without acute complications) and a control angiography 6 months after PTCA were included in the study. Events during the follow-up period were defined as death, myocardial infarction, bypass surgery, or repeat PTCA. Statistical evaluation was performed by the Fisher test, logistic regression, and life-table analysis. Restenosis (loss of > 50% of the initial gain and diameter stenosis of 50%) was found in 87 (28%) patients. During follow-up, 11 patients (5%) without restenosis (group A) and 11 (13%) patients with restenosis (group B) died (P < 0.05). In group A, 17 (8%) patients and in group B, 11 (13%) patients suffered myocardial infarction (ns); 17 group A (8%) patients and 25 (29%) group B patients had bypass surgery (P < 0.0001), and 34 (15%) group A patients and 55 (63%) group B patients underwent repeat PTCA (P < 0.0001). Logistic regression analysis identified restenosis as an independent risk factor that increases the risk of death 2.8-fold (P = 0.02), bypass surgery 5.6-fold (P < 0.0001), and repeat PTCA 10-fold (P < 0.0001). CONCLUSION: We conclude that patients with restenosis had a poorer long-term outcome than patients without restenosis. Although most patients with restenosis underwent repeat PTCA, the survival rate without any serious adverse events was only 59%, compared with 83% in patients without restenosis (P < 0.0001).

Adult↗
PubMed1998

[Flow quantification of intracardiac shunt volumes using MR phase contrast technique in the breath holding phase].

PURPOSE: Comparison of a breath-hold, velocity-encoded, phase-difference magnetic resonance (MR) sequence for intracardiac shunt flow measurement with the invasive shunt size determination by oximetry. PATIENTS AND METHODS: 10 patients with different cardiac shunts (6 ASD/3 VSD/1 PDA) and four healthy individuals were investigated using a 1.5 Tesla Siemens Vision system. For flow measurements a breath-hold, velocity-encoded, phase-difference magnetic resonance (MR) sequence was used ('through plane', FLASH 2D-sequence, TR/TE 110/5 ms, 'velocity encoding' 250 cm/s). Mean flow (ml/R-R interval) in the ascending aorta, the pulmonary trunk, and the right and left pulmonary arteries was determined. The ratio of the mean flow in the pulmonary circulation (Qp: sum of the mean flows in the right and left pulmonary arteries) and the systemic circulation (Qs: mean flow in the proximal aorta) was compared with the Qp/Qs ratios determined by the invasive oxymetric technique. Oximetry was performed within 24 hours after MR imaging. RESULTS: In the 4 healthy individuals MR flow measurement yielded a Qp/Qs ratio of 0.96 +/- 0.15. In the 10 patients with the various shunt defects, the non-invasive shunt determination by MR gave a Qp/Qs ratio of 2.09 +/- 0.67. The percentage of the calculated shunt sizes was 47.05 +/- 17.45%. In the comparison with the results determined by the invasive oxymetric technique, the MR data showed a strong correlation of r = 0.87. CONCLUSIONS: Breath-hold, velocity-encoded, phase-difference MR-technique enables a reliable quantification of cardiac shunts within a short acquisition time.

Adult↗
PubMed1998

Hypothermia as cerebroprotective measure. Experimental hypoxic exposure of brain slices and clinical application in critically reduced cerebral perfusion pressure.

An in vitro human neocortical and rodent hippocampus brain slice technique was used under repeated hypoxia to investigate the cerebroprotective effect of hypothermia. As a hallmark of the neuronal hypoxic reaction anoxic terminal negativity (ATN) was registered to test whether hypothermia delays the onset of ATN. The experiments clearly confirm an assumed protective effect of hypothermia in vitro and in vivo and give for the first time evidence of the lack of the protective effect of hypothermia once hypoxia has occurred under normothermic conditions, probably by a critical depletion of cellular ATP-stores. In patients with severe traumatic brain injury and critically low cerebral perfusion pressure mild hypothermia is able to improve clinical outcome.

Adult↗
PubMed1998

Gyri of the human neocortex: an MRI-based analysis of volume and variance.

This magnetic resonance imaging (MRI)-based morphometric analysis of cortical topography in the human brain is based upon the segmentation and parcellation of volumetric T1-weighted MRI data for a set of 20 young adult brains including 10 males and 10 females. For the most part, each parcellation unit (PU) of the neocortex corresponds to a single or a portion of a single gyrus. The volumes of each PU were computed for each brain. Subsets of PUs were also grouped so as to represent the neocortex for the frontal, temporal, parietal and occipital lobes. The coefficient of variation of the mean volume of total neocortex and that of the neocortex assigned to individual lobes cluster around 10%, whereas that of neocortex assigned to the individual gyri (PU) is more than twice that value. Approximately 80% of the total variance in gyral volume arises from determinants interactive for individual and specific gyri, while only approximately 10% of the total variance appears to be a reflection of uniform scaling to total neocortical volume. Sexual dimorphism contributes a pervasive though relatively small component of this variance. These results have implications for the study of structure-function correlation, and the proper statistical methods of handling volumetric data in morphometric studies. In addition, the nature of the covariance structure of the data will lead to future hypotheses regarding the relationships between the various potential genetic and epigenetic gyral influencing factors.

Adult↗
PubMed1998

Unit-based acute confusion resource nurse: an educational program to train staff nurses.

Despite the high prevalence of acute confusion among elders and the importance of its early detection, there are few reports of systematic efforts to increase staff competence. This article describes the development and evaluation of an 8-hour educational program designed to prepare staff nurses to perform in a new role, the unit-based acute confusion Resource Nurse (ACRN). Pre- and posttest scores were obtained for the 80 registered nurses who participated in the program. Paired t tests showed that knowledge and confidence significantly increased for participants as a result of their participation in the educational program. This program can serve as an effective model for geriatric staff education.

Acute Disease↗
PubMed1998

Inhaled prostaglandin E1 for treatment of acute lung injury in severe multiple organ failure.

UNLABELLED: Acute lung injury is characterized by hypoxemia due to pulmonary ventilation/perfusion-mismatching. I.v. administered prostaglandin E1 (PGE1), a vasodilator with a high pulmonary clearance, has been studied in acute lung injury. Inhalation of the vasodilators nitric oxide and prostacyclin improved oxygenation by selective dilation of the pulmonary vasculature in ventilated lung areas. In the present study, PGE1 inhalation was used for treatment of acute lung injury. Fifteen patients with acute lung injury defined as PaO2/fraction of inspired oxygen (FIO2) <160 mm Hg were treated with PGE1 inhalation in addition to standard intensive care. The drug was continuously delivered via a pneumatic nebulizer. Acute physiology and chronic health evaluation system II and multiple organ failure scores were (mean +/- SEM) 33 +/- 2 and 10 +/- 0.3, respectively. Inhaled PGE1 was administered for 103 +/- 17 h at a dose of 41 +/- 2 microg/h. The PaO2/FIO2 ratio increased from 105 +/- 9 to 160 +/- 17 mm Hg (P < 0.05) and to 189 +/- 25 mm Hg (P < 0.05) after 4 h and 24 h, respectively. PGE1 inhalation decreases in mean pulmonary artery pressure and central venous pressure were not statistically significant. Mean arterial pressure, pulmonary capillary wedge pressure, cardiac output, and heart rate remained unchanged. Intensive care unit mortality was 40%. The present data suggest that inhaled PGE1 is an effective therapeutic option for improving oxygenation in patients with acute lung injury. Whether inhaled PGE1 will increase survival in acute lung injury should be investigated in a controlled prospective trial. IMPLICATIONS: In patients with severe acute lung injury and multiple organ failure, inhaled prostaglandin E1 improved oxygenation and decreased venous admixture without affecting systemic hemodynamic variables. Controlled clinical trials are warranted.

APACHE↗
PubMed1998

Thoracoscopic interruption of patent ductus arteriosus compromises cardiopulmonary function in newborn pigs.

UNLABELLED: Interruption of patent ductus arteriosus (PDA) using video-assisted thoracoscopic surgery (VATS) has recently been introduced into clinical practice. To study cardiovascular and pulmonary function during VATS, we treated 16 newborn pigs (weight 1421+/-44 g) with PDA with conventional surgical interruption (CSI; n = 7) or interruption via VATS (n = 9). Measurements of hemodynamics and gas exchange were performed before, during, and after surgery. Systemic perfusion was calculated using Fick's equation. Stress hormones (ACTH, epinephrine, and norepinephrine) were determined before and after surgery. The duration of the surgical procedure was 41+/-8 min for CSI and 49+/-9 min for VATS (mean+/-SEM). With VATS, PaO2 decreased during and after surgery (P < 0.05), whereas alveolar-arterial PO2 difference (PA-aO2) and PaCO2 were increased (P < 0.05). Compared with CSI after surgery, PaO2 with VATS was decreased (130+/-10 vs 171+/-12 mm Hg; P < 0.05). Systemic perfusion was lower during VATS (76.7% of baseline) than during CSI (107% of baseline; P < 0.05). Heart rate, mean arterial pressure, and right ventricular end-diastolic pressure remained unchanged with both treatments. Stress hormones were comparable between groups. We conclude that systemic perfusion and oxygenation were impaired during VATS compared with CSI. Therefore, VATS may be contraindicated in pediatric patients with minor cardiopulmonary reserve. IMPLICATIONS: We studied the cardiopulmonary effects of endoscopic interruption of the patent ductus arteriosus in an animal model of newborn pigs. Gas exchange and systemic perfusion were impaired compared with conventional interruption of the patent ductus arteriosus after thoracotomy.

Animals↗
PubMed1998

A case of severe cerebral trauma in a patient under chronic treatment with cyclosporine A.

A case of severe cerebral head injury in a child, chronically treated with cyclosporine A after orthotopic liver transplantation, is presented. The initial Glasgow Coma Scale score after the motor vehicle accident was 3, and computed tomography showed multiple sites of intracerebral bleeding, an epidural hematoma, and signs of perifocal edema. Although these lesions are normally associated with a poor outcome, the child recovered unexpectedly well. In brain injury, a lucid interval can be followed by secondary neurologic deterioration due to a loss of high-energy metabolites, a release of neurotransmitters, and an increase in intracellular Ca2+. These events finally led to cell damage in the penumbra of an ischemic infarction. Among other drugs, immunosuppressants such as cyclosporine A have been shown to exhibit neuroprotective properties in experimental models if given during this time interval of secondary neurologic deterioration. Although human data on these effects are still lacking, we conclude that neuroprotective actions of cyclosporine A may have been involved in the favorable outcome in this 14-year-old boy.

Adolescent↗
PubMed1998

Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in young Chinese adults.

The aim of this study was to determine the presence or absence of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in young Chinese adults and to examine the A. actinomycetemcomitans isolates from positive subjects with regard to the serotype distribution, presence of the leukotoxin gene lktA and the promoter for the leukotoxin operon as well as the incidence of phage Aa phi 23. Sixty subjects, working in a knitting factory in the Province of Guangzhou, People's Republic of China, were investigated. Subgingival microbial samples were taken from both upper first molars. They were cultured both anaerobically and in 5% CO2. P. gingivalis was found in 33 subjects. On average, it constituted 7% of the total anaerobic cultivable counts. A. actinomycetemcomitans was detected in 37 subjects of which seven yielded counts > 10(5). Twenty-one subjects were positive for both organisms. A. actinomycetemcomitans serotype a was found in 9 subjects, serotype c was found in 23 and serotype e in 5. A. actinomycetemcomitans serotypes b and d were not detected in any subjects. Presence of the leukotoxin gene lktA was demonstrated for all A. actinomycetemcomitans isolates; however, none of the A. actinomycetemcomitans strains from the present study had a deletion in the promoter region of the leukotoxin operon. The results of this investigation show a high frequency of the putative periodontal pathogens P. gingivalis and A. actinomycetemcomitans and corroborate the concept that there is variation in virulence and pathogenic potential among isolates from different subjects.

Adolescent↗