Renal medullary carcinoma: can early diagnosis lead to long-term survival?
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Adult↗
Biomedical subjects
C Simon
Publications and source records attributed to C Simon.
Alpha activity and cardiac correlates: three types of relationships during nocturnal sleep.
OBJECTIVE: We examined simultaneously alpha activity and cardiac changes during nocturnal sleep, in order to differentiate non-rapid eye movement (NREM) sleep, REM sleep, and intra-sleep awakening. METHODS: Ten male subjects displaying occasionally spontaneous intra-sleep awakenings underwent EEG and cardiac recordings during one experimental night. The heart rate and heart rate variability were calculated over 5 min periods. Heart rate variability was estimated: (1) by the ratio of low frequency (LF) to high frequency (HF) power calculated from spectral analysis of R-R intervals; and (2) by the interbeat autocorrelation coefficient of R-R intervals (rRR). EEG spectral analysis was performed using a fast Fourier transform algorithm. RESULTS: Three types of relationships between alpha waves (8-13 Hz) and cardiac correlates could be distinguished. During NREM sleep, alpha activity and cardiac correlates showed opposite variations, with high levels of alpha power associated with decreased heart rate, rRR and LF/HF ratio, indicating low sympathetic activity. Conversely, during REM sleep, alpha activity was low whereas heart rate, rRR, and the LF/HF ratio peaked, indicating high sympathetic activity. During intra-sleep awakenings, alpha activity and cardiac correlates both increased. No difference in time-course between alpha 1 (8-10 Hz) and alpha 2 (10-13 Hz) activity could be shown. Alpha waves occurred in fronto-central areas during slow wave sleep (SWS), migrated to posterior areas during REM sleep, and were localized in occipital areas during intra-sleep awakenings. CONCLUSIONS: These results suggest that alpha waves are not simply a sign of arousal, as is commonly thought. Fronto-central alpha waves, associated with decreased heart rate, possibly reflect sleep-maintaining processes.
Adult↗
Secondary structure and conserved motifs of the frequently sequenced domains IV and V of the insect mitochondrial large subunit rRNA gene.
We have analysed over 400 partial insect mitochondrial large subunit (mit LSU) sequences in order to identify conserved motifs and secondary structures for domains IV and V of this gene. Most of the secondary structure elements described by R. R. Gutell et al. (unpublished) for the LSU were identified. However, we present structures for helices 84 and 91 that are not recognized in previous universal models. The portion of the 16S gene containing domains IV and V is frequently sequenced in insect molecular systematic studies so we have many more sequences than previous studies which focused on the complete mitochondrial LSU molecule. In addition, we have the advantage of investigating several sets of closely related taxa. Aligned sequences from thirteen insect orders and nine secondary structure diagrams are presented. These conserved sequence motifs and their associated secondary structure elements can now be used to facilitate the alignment of other insect mit LSU sequences.
Animals↗
High intensity focused ultrasound effect on cardiac tissues: potential for clinical application.
High intensity focused ultrasound (HIFU) is an evolving technology with potential therapeutic applications. Utilizing frequencies of 500 kHz to 10 MHz, HIFU causes localized hyperthermia at predictable depths without injuring intervening tissue. Applications in neurosurgery, urology, oncology and, more recently, cardiology for selective cardiac conduction tissue ablation have been promising. A 'noninvasive' technique for causing localized tissue damage to relieve hemodynamic and life-threatening obstruction in patients with congenital cardiac anomalies could replace more invasive procedures. We, therefore, investigated the ability of HIFU to create lesions in mammalian cardiac tissues ex vivo. Porcine valve leaflet, canine pericardium, human newborn atrial septum, and right atrial appendage were studied. Specimens were mounted and immersed in a water bath at room temperature. Using a 1-MHz phased array transducer, ultrasound energy was applied with an acoustic intensity of 1630 W/cm(2) or 2547 W/cm(2) until a visible defect was created (duration 3 to 25 sec). Macroscopic and microscopic examination demonstrated precise defects ranging from 3 to 4 mm in diameter. No damage was identified to the surrounding tissues. Our study concluded that HIFU can create precise defects in different cardiac tissue without damage to the surrounding tissue. Further investigation is needed to assess potential clinical uses of this technology.
Animals↗
Oral manifestations of pediatric vertical HIV infection.
To assess the prevalence and prognostic significance of the history of oral manifestations in children with human immunodeficiency virus infection (HIV), a cohort study of 73 children with vertical HIV infection was conducted. The study subjects were examined every 6 months for oral manifestations. The period prevalence of oral manifestations ranged from a low of 1% for submandibular enlargement and 3% for hairy leukoplakia to a high of 36% for xerostomia and 51% for cervical lymphadenopathy. The occurrence of oral manifestations did not change significantly over time from 1995 to 1998. Finally, the odds of occurrence of cervical lymphadenopathy, xerostomia, and oral candidiasis were greater among children in whom these manifestations had been diagnosed in the preceding 6-18 months than in children without prior diagnosis. Oral manifestations are significant clinical outcomes in pediatric vertical HIV infection, particularly for children diagnosed previously with an oral manifestation.
Candidiasis, Oral↗
The performance of several multiple-sequence alignment programs in relation to secondary-structure features for an rRNA sequence.
The performances of five global multiple-sequence alignment programs (CLUSTAL W, Divide and Conquer, Malign, PileUp, and TreeAlign) were evaluated using part of the animal mitochondrial small subunit (12S) rRNA molecule. Conserved sequence motifs derived from an alignment based on secondary structural information were used to score how well each program aligned a data set of five vertebrate and five invertebrate taxa over a range of parameter values. All of the programs could align the motifs with reasonable accuracy for at least one set of parameter conditions, although if the whole sequence was considered, similarity to the structural alignment was only 25%-34%. Use of small gap costs generally gave more accurate results, although Malign and TreeAlign generated longer alignments when gap costs were low. The programs differed in the consistency of the alignments when gap cost was varied; CLUSTAL W, Divide and Conquer, and TreeAlign were the most accurate and robust, while PileUp performed poorly as gap cost values increased, and the accuracy of Malign fluctuated. Default settings for the programs did not give the best results, and attempting to select similar parameter values in different programs did not always result in more similar alignments. Poor alignment of even well-conserved motifs can occur if these are near sites with insertions or deletions. Since there is no a priori way to determine gap costs and because such costs can vary over the gene, alignment of rRNA sequences, particularly the less well conserved regions, should be treated carefully and aided by secondary structure and conserved motifs. Some motifs are single bases and so are often invisible to alignment programs. Our tests involved the most conserved regions of the 12S rRNA gene, and alignment of less well conserved regions will be more problematical. None of the alignments we examined produced a fully resolved phylogeny for the data set, indicating that this portion of 12S rRNA is insufficient for resolution of distant evolutionary relationships.
Algorithms↗
Pluripotential mesenchymal cells repopulate bone marrow and retain osteogenic properties.
Precursor cells, isolated from bone marrow, can develop into various cell types and may contribute to skeletal growth, remodeling, and repair. The D1 cell line was cloned from a multipotent mouse bone marrow stromal precursor and has osteogenic, chondrogenic, and adipogenic properties. The osteogenic phenotype of these precursor cells is relevant to the process of fracture healing and osteointegration of prosthetic implants. The D1 cells were labeled genetically using a replication incompetent retroviral vector encoding beta-galactosidase, an enzyme which is used as a marker. Labeled cells are readily identifiable by staining with 5-bromo-4-chloro-3-indoyl-beta-D-galactoside and by flow cytometry, and retain the desired osteogenic characteristics in vivo as shown by von Kossa staining, alkaline phosphatase assay, an increase in cyclic adenosine monophosphate in response to parathyroid hormone, osteocalcin messenger ribonucleic acid production, and bone formation in diffusion chambers. In addition, the cells cloned from marrow stroma repopulate the marrow of host mice, persist for several weeks, and retain their osteogenic potential ex vivo. The data suggest that such cells may be used to replenish the number of osteoprogenitors in marrow, which appear to decrease with age, thereby leading to recovery from bone loss and improved bone growth and repair. Labeling these cells creates a model in which to study the potential of such cells to participate in fracture repair, ingrowth around prosthetic implants, treatment of osteoporosis, and to explore the possibility of gene delivery to correct mutations or defects in metabolism that are responsible for certain skeletal abnormalities.
Animals↗
Pilot study of hydroxyurea in human immunodeficiency virus-infected children receiving didanosine and/or stavudine.
OBJECTIVE: To evaluate the safety and antiviral and immunologic effects of hydroxyurea given with didanosine (ddI) and/or stavudine (d4T) to symptomatic HIV-infected children. METHODS: HIV-infected children with a history of long term nucleoside antiretroviral therapy were treated orally with hydroxyurea (initial dose, 10 to 20 mg/kg once daily; final dose, 30 mg/kg once daily), added to existing therapy that included ddI and/or d4T. RESULTS: Sixteen children were enrolled (mean age, 6.7 years; range, 1.8 to 13.4 years). Antiretroviral therapy used with hydroxyurea included d4T/ddI (12), ddI (2), d4T (1) and d4T/lamivudine (1). Children received between 24 and 48 weeks of therapy, which was well-tolerated. Hydroxyurea was held temporarily during the first month of therapy in 4 cases because of neutropenia; all patients resumed hydroxyurea at full dosage without recurrence of neutropenia. No patient discontinued therapy permanently because of intolerance or toxicity. For the 13 children who completed 48 weeks of study treatment, the mean plasma HIV RNA concentration decreased from 4.6 log10 copies/ml at baseline to 4.2 log10 copies/ml at study Week 48 (P = 0.035, paired t test). Eight of these 13 children experienced a 0.5-log10 copies/ml or greater drop in HIV RNA concentration in the 48 weeks of study treatment. Appreciable changes in CD4+ lymphocyte percentage were not noted. CONCLUSIONS: Hydroxyurea, added to existing therapy with ddI and/or d4T, was well-tolerated and safe in HIV-infected children. Evidence of antiviral activity was observed in some cases.
Adolescent↗
Genetic evidence for assortative mating between 13-year cicadas and sympatric "17-year cicadas with 13-year life cycles" provides support for allochronic speciation.
Thirteen-year cicadas of brood XIX from northern Arkansas, Missouri, and southern Illinois (lineage A) are known to be genetically different at two marker loci (mitochondrial DNA and abdominal color) from 13-year cicadas to the south (lineage B) that emerge in the same year. Because 17-year cicadas from all broods (year classes) are indistinguishable from lineage A at these two marker loci, previous workers suggested that the lineage A cicadas of 13-year brood XIX were derived from 17-year cicadas by life-cycle switching (allochrony). Data presented here show that, over the same northern geographic range, lineage A is also present in 13-year cicadas belonging to brood XXIII (which always emerges four years later than brood XIX). Detailed sampling along the putative life-cycle-switching boundary in 13-year brood XXIII revealed a previously unsuspected broad zone of overlap where populations contained individuals of both lineages A and B. Despite this sympatry, and previous reports of a lack of behavioral barriers to interbreeding, a strong correlation between mitochondrial haplotype and abdominal color suggests that assortative mating has taken place. Lineage A 13-year cicadas from both broods XIX and XXIII are only found within a gap in the spatial distribution of 17-year cicadas. This, in combination with the lack of differentiation between lineage A 13- and 17-year cicadas at the marker loci and new behavioral data for 13-year brood XIX, suggests a recent derivation of all northern 13-year cicadas from the 17-year cicadas via life-cycle switching. We discuss the implications of these allochronic shifts for speciation.
Animals↗
Pharmacologic characteristics of indinavir, didanosine, and stavudine in human immunodeficiency virus-infected children receiving combination therapy.
The use of human immunodeficiency virus (HIV) protease inhibitors in children has lagged behind that in adults because of the lack of suitable pediatric formulations and information on safe and effective dosing regimens. This study was designed to obtain pharmacokinetic information on indinavir, administered to HIV-infected children also receiving therapy with two nucleoside agents, and to explore relationships between pharmacokinetic parameters and anti-HIV effect. Indinavir was initiated at a dose of 500 mg/m(2) every 8 h. Plasma indinavir concentrations were measured every 4 weeks; the dose or dosing interval was adjusted to maintain trough concentrations of > or =0.1 mg/liter. All children were evaluated clinically at baseline and every 4 weeks. Plasma HIV RNA was quantitated at baseline and at weeks 4, 12, and 24. Eighteen children participated in this study. The average daily dose of indinavir was 2,043 mg/m(2); nine children received indinavir at 6-h intervals. Pharmacokinetic characteristics of indinavir (mean +/- standard deviation) were the following: oral clearance, 1.4 +/- 0.5 liters/h/kg; half-life, 1.1 +/- 0.43 h; and trough concentration, 0. 29 +/- 0.32 mg/liter. In nine children that completed 24 weeks of therapy, the baseline-to-week-24 change in HIV RNA level was related to indinavir trough concentration and didanosine area under the curve. This study illustrates the ability to obtain pharmacokinetic information from children during routine clinic visits and to use this information to provide a safeguard against underdosing. The incorporation of pharmacologic knowledge with virologic, immunologic, and behavioral considerations should result in improved clinical outcomes for children infected with HIV.
Anti-HIV Agents↗
Twenty-four-hour rhythms of plasma glucose and insulin secretion rate in regular night workers.
To determine whether the ultradian and circadian rhythms of glucose and insulin secretion rate (ISR) are adapted to their permanent nocturnal schedule, eight night workers were studied during their usual 24-h cycle with continuous enteral nutrition and a 10-min blood sampling procedure and were compared with 8 day-active subjects studied once with nocturnal sleep and once with an acute 8-h-shifted sleep. The mean 24-h glucose and ISR levels were similar in the three experiments. The duration and the number of the ultradian oscillations were influenced neither by the time of day nor by the sleep condition or its shift, but their mean amplitude increased during sleep whenever it occurred. In day-active subjects, glucose and ISR levels were high during nighttime sleep and then decreased to a minimum in the afternoon. After the acute sleep shift, the glucose and ISR rhythms were split in a biphasic pattern with a slight increase during the night of deprivation and another during daytime sleep. In night workers, the glucose and ISR peak levels exhibited an 8-h shift in accordance with the sleep shift, but the onset of the glucose rise underwent a shift of only 6 h and the sleep-related amplification of the glucose and ISR oscillations did not occur simultaneously. These results demonstrate that despite a predominant influence of sleep, the 24-h glucose and ISR rhythms are only partially adapted in permanent night workers.
Activity Cycles↗
Leptin and leptin receptor are expressed in the human endometrium and endometrial leptin secretion is regulated by the human blastocyst.
Embryonic implantation is a crucial event for the human reproductive function. Cytokines and paracrine molecules have been proposed as putative local regulators of this process. The leptin or the OB protein has been linked to the reproductive function and inflammatory response. In the present study, we describe for the first time the expression of leptin and leptin receptor (long form) in the secretory endometrium and that endometrial leptin secretion is regulated in vitro by the human blastocyst. Leptin and leptin receptor messenger RNA and protein were identified in secretory endometrium and in cultured endometrial epithelial cells (EECs) by RT-PCR, Western blot, and immunohistochemistry. The concentrations of immunoreactive leptin secreted by human embryos alone or cocultured with EECs were also assessed. We found that human blastocysts secrete significantly higher levels of leptin than arrested embryos. In contrast, leptin concentrations secreted by arrested embryos cocultured with EECs were significantly higher than blastocysts cocultured with EECs. These findings suggest that the human endometrium is a site for local production and a target tissue for circulating leptin. Expression of leptin and its functional receptor in the endometrium and regulation of endometrial leptin secretion by the human embryo suggests that the leptin system may be implicated in the human implantation process.
Adult↗
Electrostatic forces on the surface of metals as measured by atomic force microscopy.
Electrostatic forces play an important role in modulating the interaction of plasma proteins and blood cellular components with the surface of the vascular endothelium. Based on the concept that electrostatic forces residing on the surface of metal intravascular prostheses, such as the stent, also are critical in influencing blood interactions with those surfaces and the vascular wall, these studies were designed to measure these forces on 4 metals using atomic force microscopy (AFM). AFM measurements performed in a low saline aqueous medium at physiological pH indicate a similar net electronegative surface charge level for gold and 316l stainless steel that is significantly higher than the level measured on an electropolished Nitinol surface. Heat oxidation of the Nitinol surface increased the overall electronegativity and created a more homogeneous surface charge distribution. This study demonstrates that AFM force measurements can be a valuable approach to understanding the electrostatic surface of metallic as well as other biomaterials that may be important in understanding how these surfaces influence vascular healing at intravascular interventional sites.
Biocompatible Materials↗
Protein interactions with endovascular prosthetic surfaces.
Blood protein interaction with prosthetic surfaces seems to be the initial step in the chain of events leading to tissue incorporation of endovascular devices. This paper focuses on the relationship between surface free energy and protein adsorption on metals and polymers commonly used for fabricating vascular prosthetic devices. Our results support a relationship between surface energy and protein adsorption. Albumin was more easily eluted than fibrinogen and fibronectin from most metals and all polymeric surfaces considered. Following elution, metals retained a larger fraction of protein as compared to polymers.
Albumins↗
Influence of topography on endothelialization of stents: clues for new designs.
To evaluate the influence of stent design on endothelialization of the stented surface, we placed trapezoidal objects of variable thickness on a confluent culture of endothelial cells and subjected the assembly to flow and shear conditions similar to those found in arteries. After 24 h, we measured and analyzed the area on top of the objects covered by cells and the maximum migration distance from the borders. In addition, we evaluated areas devoid of cells surrounding the objects, which developed after exposure of the assembly to flow. The cell-covered area and migration distance significantly decreased on objects 75 microns thick, and it was nonexistent on objects 250 microns thick. Areas devoid of cells or gaps were largest adjacent to the downflow side of the object, disposed transversely to flow. Cell gaps were smallest along the side aligned with flow. In conclusion, endothelial cell coverage may be impaired by stent wall thickness larger than 75 microns. It is likely that this impairment is related to flow disturbances impairing cell attachment.
Cell Movement↗
1997 Graduates Speak: initial employment experiences of residency and fellowship graduates.
OBJECTIVE: The American College of Radiology sought to detail the initial employment experience of 1997 diagnostic radiology graduates and recent trends. MATERIALS AND METHODS: In early 1998, questionnaires were mailed to all graduates; 65% responded. Results were compared with similar surveys of 1995 and 1996 graduates. RESULTS: Much as in past years, immediately after graduation 4% of residency graduates and 9% of fellowship graduates spent some time working as a locum tenens, working outside radiology, or unemployed, but by 6-12 months after graduation, 2% or fewer were not employed. The median fellowship graduate's salary was 5% greater than in 1996. Twelve percent of fellowship graduates were in non-ownership-track jobs, much the same as in earlier years. Thirty-two percent had one or more of 12 possibly undesirable job characteristics, down from 39% in 1996; 14% not only had, but actually disliked, one or more of these characteristics, much the same as in 1996, but down from 23% in 1995. Multivariate analysis showed that women graduates were more likely than men to have had serious employment difficulties in the immediate postgraduation months; and that graduates having a spouse who also had to find a job in the same area were more likely than others to be in a putatively "seriously undesirable" location or in "holding pattern" employment while looking for something better or more permanent. CONCLUSION: Unemployment remained very low. Some other indicators of the employment market showed improvement. Factors expected to affect employment outcomes-for example, training program quality or having major non-spouse-related restrictions on job location-had surprisingly little effect.
Education, Medical, Graduate↗
[Juvenile goiter in a goat herd in northwest Germany].
A continuous increase in the circumference of the thyroid gland was observed in four goat kids (44.4%) of the breed of White German Goat between the third and fourth month in a herd comprising White German Goats and Coloured German Goats. Clinical, laboratory diagnostic and chemically analytical results have been obtained, illustrated and compared with the equivalent parameters from healthy control herds without pathological findings. The thyroidal secretion rate and the milk iodine content were highly significant reduced in the affected flock in comparison with the control group. The feed which was given to the affected group did not cover the nutritional requirement of pregnant, lactating and growing goats. At 40-50 mg/l, the nitrate content of the water was close to the tolerance of 50 mg/l. It can be deduced from the findings available that the case described above is a synergetic combination of a primary iodine deficiency, based on an inefficient iodine supply and of a secondary iodine deficiency resulting from a super elevated nitrate content of the drinking water.
Animal Feed↗
[Role of bariatric surgery in the obese diabetic].
Bariatric surgery can be proposed to address severe obesity associated with comorbid conditions, when medical treatment has failed. Three surgical techniques are currently available, including 2 using coelioscopy. Short term results are encouraging regarding weight loss, which is linked with a reduction in comorbid conditions such as glucose intolerance. The number of studies is too low to assess long term results. Surgery in obese diabetic patients rapidly improves insulin resistance, thus allowing to reduce antidiabetic treatment. However these positive effects should be balanced with surgery-linked complications, therefore gastroplasty indications should be thoroughly examined.
Diabetes Mellitus↗