Biomedical subjects

C Simon

Publications and source records attributed to C Simon.

At least 73 records · Page 4Linked to original sources

PubMed2000

[Vestibular neurotomy by a retrosigmoid approach: functional results. Evaluation through a triple clinical approach (otoneurologic, orthoptic and physical medicine)].

Vestibular neurotomy remains the surgical procedure of choice in the management of peripheral vertigo resistant to the usual medical treatment, for patients with preserved hearing. Menière's disease generally sums up most of the surgical indications. The authors report a personnel series of patients who underwent vestibular neurotomy during the last five years, from January to December 1998. The aim of this study was to assess with a 6 months to 3.5 years follow-up, postoperative complications and functional results, particularly the improvement of dizziness, residual unsteadiness and its impact on quality of life, and the recovery of socio-professional and physical activities. Of a total of 41 patients, 21 were evaluated by both an otoneurologic and physical medicine approach, to analyze the main sensory components of equilibrium (vestibular, proprioceptive, cervical, visual). In most of the cases, the results show disappearance of vertigo which was the main complaint. However, disabling residual instability is common in those patients who was present both a cervical pathology and binocular visual impairment or a defect in convergence, often unrecognised. The authors emphasise the necessity of a cervical examination and orthoptic investigations in addition to the vestibular assessment. This multi-disciplinary approach allows better identification of the different factors (vestibular, cervical, orthoptic) and lead to specific rehabilitation which can permit the patient with residual unsteadiness to return to work and lifestyle, the real measure of success of vestibular neurotomy.

Adult↗

PubMed1999

Adult pseudosarcoma of the bladder.

Pseudosarcomatous tumor of the urinary bladder is an unusual benign proliferative lesion that poses a diagnostic dilemma for both the urologist and pathologist. Its clinical and histologic features mimic a malignant neoplasm, although simple excision is curative. Although similar lesions have been reported in multiple extravesicle locations, most commonly the lung, bladder lesions have only recently been reported. We describe 2 cases of pseudosarcomatous bladder tumors presenting in patients with no known risk factors. We review clinical, histologic, and management issues in these patients. By recognizing the existence of this lesion, possible extensive and inappropriate surgery may be avoided.

Adult↗

PubMed1999

May-Thurner syndrome in an adolescent: persistence despite operative management.

We describe a patient with May-Thurner syndrome who underwent operative transection and transposition of the right common iliac artery without direct venous repair, because preoperative and intraoperative intravascular ultrasound scans were negative for "spurs" in the left common iliac vein. When symptoms and signs persisted, a postoperative magnetic resonance venogram (MRV) showed severe stenosis in the left common iliac vein. Progressive, but incomplete, clinical improvement occurred with conservative management.

Adolescent↗

PubMed1999

PD 098059, an inhibitor of ERK1 activation, attenuates the in vivo invasiveness of head and neck squamous cell carcinoma.

Increased mortality of patients with oral cancer largely reflects the local and regional spread of the disease. The invasiveness of these tumours requires hydrolases which are regulated through AP-1-dependent transcriptional mechanisms. Since the amount/activity of transcription factors bound to the AP-1 motif are regulated partly through the extracellular signal-regulated kinases (ERK1/ERK2), we determined the effect of PD 098059, an inhibitor of ERK1/ERK2 activation, on the in vivo invasiveness of a human squamous cell carcinoma cell line (UM-SCC-1) derived from the oral cavity. We utilized the floor of mouth musculature consisting of the mylohyoid, geniohyoid and genioglossus muscle (which are sequentially arranged), as a natural barrier to assess tumour spread in vivo in the nude mouse. Mice were inoculated with tumour cells superficial to the mylohyoid muscle. After 18 days, tumours were injected with either empty liposomes (control) or liposomes containing 5 microM PD 098059 and, after an additional 22 days, the jaws of mice examined histologically. Highly infiltrative tumours, which had penetrated the genioglossus muscle, were evident in 10/12 control mice. In contrast, in 9/12 mice in which the tumours were injected with PD 098059, tumours did not extend beyond the mylohyoid or geniohyoid muscles. Tumours penetrated bone nutrient canals in 7/12 control mice but in only 3/12 PD 098059-treated mice. Neurotropism, characteristic of aggressive oral squamous cell carcinoma, was evident in 6/12 control mice but was completely abolished (0/12 mice) in the PD 098059-treated mice. Using a staging system based on the muscle layer involved, neurotropism, as well as bone involvement, we found the inhibition of invasion to be statistically significant (P < 0.01). The reduced invasiveness of the PD 098059-liposome-treated oral cancers was associated with diminished 92-kDa type IV collagenase and ERK1/ERK2 activities but was not a consequence of a slower tumour growth rate. This is the first study to demonstrate reduced in vivo invasiveness of a malignancy brought about by an inhibitor of ERK1/ERK2 activation. These results raise the exciting possibility that second generation PD 098059 congeners may reduce the spread of the disease in patients afflicted with oral cancers.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1999

Does parental breastfeeding knowledge increase breastfeeding rates?

OBJECTIVE: Although improving mothers' knowledge about breastfeeding can increase rates and duration of breastfeeding, little is known about the influence of fathers' knowledge. The purpose of this study was to assess the knowledge of mothers and fathers about breastfeeding before and after receiving postpartum advice and its relationship to the frequency of breastfeeding. METHODS: A clinical trial was performed with mothers and fathers of normal children born at the Hospital de Clínicas de Porto Alegre, Brazil, between July 1994 and March 1995. The study intervention consisted of postpartum advice supplied by means of a video film discussing basic topics of breastfeeding, an explanatory leaflet, and open discussion after viewing the video. The first 208 couples comprised the control group, the next 197 comprised experimental group 1, and the remaining 196 comprised experimental group 2. Immediately after delivery, mothers and fathers in the three groups answered a test on breastfeeding knowledge; they completed the same test at the end of the first month. All families received home visits at the end of the first, second, fourth, and sixth months, or until breastfeeding ceased. Logistic regression was used to evaluate the association between the mothers' and fathers' knowledge and frequency of breastfeeding. RESULTS: Postpartum advice increased the breastfeeding knowledge of mothers and fathers. The mothers with the highest level of knowledge had a 6.5 times higher chance of exclusively breastfeeding at the end of the third month, and 1.97 times higher chance of continuing breastfeeding to the end of the sixth month compared with other mothers. The fathers' knowledge also significantly influenced breastfeeding rates. The children whose fathers knew more had a 1.76 higher chance of being exclusively breastfed at the end of the first month, and 1.91 higher chance of receiving maternal milk at the end of the third month. CONCLUSION: A simple, inexpensive strategy can increase the level of breastfeeding knowledge of mothers and fathers and, consequently, have a positive impact on the frequency of breastfeeding.

Adult↗

PubMed1999

mtDNA analysis of Nile River Valley populations: A genetic corridor or a barrier to migration?

To assess the extent to which the Nile River Valley has been a corridor for human migrations between Egypt and sub-Saharan Africa, we analyzed mtDNA variation in 224 individuals from various locations along the river. Sequences of the first hypervariable segment (HV1) of the mtDNA control region and a polymorphic HpaI site at position 3592 allowed us to designate each mtDNA as being of "northern" or "southern" affiliation. Proportions of northern and southern mtDNA differed significantly between Egypt, Nubia, and the southern Sudan. At slowly evolving sites within HV1, northern-mtDNA diversity was highest in Egypt and lowest in the southern Sudan, and southern-mtDNA diversity was highest in the southern Sudan and lowest in Egypt, indicating that migrations had occurred bidirectionally along the Nile River Valley. Egypt and Nubia have low and similar amounts of divergence for both mtDNA types, which is consistent with historical evidence for long-term interactions between Egypt and Nubia. Spatial autocorrelation analysis demonstrates a smooth gradient of decreasing genetic similarity of mtDNA types as geographic distance between sampling localities increases, strongly suggesting gene flow along the Nile, with no evident barriers. We conclude that these migrations probably occurred within the past few hundred to few thousand years and that the migration from north to south was either earlier or lesser in the extent of gene flow than the migration from south to north.

DNA Mutational Analysis↗

PubMed1999

A program of acquired immune deficiency syndrome education for nurses in Romania.

After the fall of the communist government in Romania, many children were found to be human immunodeficiency virus (HIV) infected. The majority of these children were abandoned and currently live in orphanages. The children have been cared for on a day-to-day basis by nurses with little general nursing education and even less HIV education. The Romanian-American Pediatric AIDS Education and Clinical Research Program was established at Texas Children's Hospital and Baylor College of Medicine in May, 1996 to aid in the education of Romanian nurses. Syllabi developed by the U.S. nursing team were initially piloted in three pediatric HIV centers in Romania in July, 1997. Since that time, two annual nursing symposia have been held offering topics on general pediatrics and HIV-related content. The purpose of this article is to describe a program of HIV education for nurses in Romania.

Child↗

PubMed1999

Neuroendocrine processes underlying ultradian sleep regulation in man.

Sleep is not a uniform state but is characterized by the cyclic alternation between rapid eye movement (REM) and non-REM sleep with a periodicity of 90-110 min. This cycle length corresponds to one of the oscillations in electroencephalographic (EEG) activity in the delta frequency band (0.5-3.5 Hz), which reflect the depth of sleep. To demonstrate the intimate link between EEG and neuroendocrine rhythmic activities in man, we adopted a procedure permitting simultaneous analysis of sleep EEG activity in the delta band and of two activating systems: the adrenocorticotropic system and the autonomic nervous system. Adrenocorticotropic activity was evaluated by calculating the cortisol secretory rate in blood samples taken at 10-min intervals. Autonomic activity was estimated by two measures of heart rate variability: 1) by the ratio of low-frequency (LF) to high-frequency (HF) power from spectral analysis of R-R intervals; and 2) by the interbeat autocorrelation coefficient of R-R intervals (rRR intervals between two successive cardiac beats). The results revealed that oscillations in delta wave activity, adrenocorticotropic activity, and autonomic activity are linked in a well-defined manner. Delta wave activity developed when cortisol secretory rates had returned to low levels and sympathetic tone was low or decreasing, as reflected by a low LF/HF ratio and by low levels in rRR. Conversely, the decrease in delta wave activity occurred together with an increase in the LF/HF ratio and in rRR. REM sleep was associated with a decrease in cortisol secretory rates preceding REM sleep onset, whereas the LF/HF ratio and rRR remained high. These results demonstrate a close coupling of adrenocorticotropic, autonomic, and EEG ultradian rhythms during sleep in man. They suggest that low neuroendocrine activity is a prerequisite for the increase in slow wave activity.

Adult↗

PubMed1999

[Minor functional disorders after surgery of acoustic nerve neuroma].

UNLABELLED: Acoustic neuromas must be removed surgically, otherwise serious complications may occur. Removal of an acoustic neuroma most often leads to disorders of balance, hearing, and sometimes facial motor function. Many earlier studies have approached the hearing and facial motor function. However, the facial nerve also comprises sensory and secretory fibers which, when injured, may produce minor disorders affecting patient's quality of life. The purpose of this work was to evaluate the quality of life, secretory and taste disorders after acoustic neuroma surgery. PATIENTS AND METHOD: Among patients operated on between May 1985 and May 1996, we selected only those who presented a normal facial function 3 months after surgery. We thus selected 93 patients and sent them a questionnaire in December 1997. We received 74 answers. RESULTS: The period between the operation and the dispatch of the questionnaire was on an average 5.5 years (range 19 months-12 years 9 months). Impairment of quality of life was frequent (59% of cases), and changing way of life less so (30%). 74% of the patients described balance disorders. One-quarter of the patients indicated they experienced disorders of facial mobility. Only 3 patients had no disorder. CONCLUSION: Secretory and taste disorders are frequent after neuroma surgery. Despite their mildness, patients should be advised accordingly because of possible impact on quality of life. This study also points out the lack of precision in the estimation of facial mobility. A better evaluation of patient complaints would be useful.

Adult↗

PubMed1998

Inhibition of the p38 mitogen-activated protein kinase by SB 203580 blocks PMA-induced Mr 92,000 type IV collagenase secretion and in vitro invasion.

Although the p38 mitogen-activated protein kinase (MAPK) has been implicated in signal transduction events, its role in regulating the Mr 92,000 type IV collagenase matrix metalloprotease-9 (MMP-9) and in vitro invasiveness in cancer has not yet been determined. We made the surprising observation that, in a human squamous cell carcinoma cell line (UM-SCC-1), phorbol ester-enhanced MMP-9 secretion and in vitro invasiveness were associated with a strong activation of the p38 MAPK and its downstream target, MAPK-activated protein kinase-2. To determine the role of p38 activation in these events, we investigated the effect of SB 203580, a novel specific p38 inhibitor, on protease expression and in vitro invasion of these cells. We found that inhibition of p38 by SB 203580 resulted in the almost complete reduction of phorbol myristate acetate-induced MMP-9 secretion but not of urokinase-type plasminogen activator secretion. In contrast, the activation of a transiently transfected wild-type MMP-9 promoter by MEKK-1, a specific c-Jun NH2-terminal kinase activator, was only marginally inhibited by the compound, arguing for the specificity of SB 203580. Moreover, phorbol myristate acetate-enhanced in vitro invasion was completely blocked by SB 203580, whereas p38 inhibition had little effect on growth. These findings suggest that activation of p38 may contribute to a more invasive phenotype in vitro, possibly via the expression of MMP-9, and that targeting of p38 using SB 203580 may provide a novel means of controlling invasion of cancers in which this MAPK is activated.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed1998

A pilot study of combination therapy with indinavir, stavudine (d4T), and didanosine (ddI) in children infected with the human immunodeficiency virus.

Twelve children infected with the human immunodeficiency virus were treated orally with indinavir, stavudine, plus didanosine for 12 to 48 weeks. Therapy was limited in some cases by nonadherence, intolerance, toxicity, and virologic failure. Marked increases in CD4+ lymphocyte counts and decreases in plasma human immunodeficiency virus RNA concentrations suggest that the regimen has potent antiviral activity.

Administration, Oral↗

PubMed1998

Expression of ARNT, ARNT2, HIF1 alpha, HIF2 alpha and Ah receptor mRNAs in the developing mouse.

The basic helix-loop-helix-PAS (bHLH-PAS) protein ARNT is a dimeric partner of the Ah receptor (AHR) and hypoxia inducible factor 1 alpha(HIF1 alpha). These dimers mediate biological responses to xenobiotic exposure and low oxygen tension. The recent cloning of ARNT and HIF1(homologues (ARNT2 and HIF2 alpha) indicates that at least six distinct bHLH-PAS heterodimeric combinations can occur in response to a number of environmental stimuli. In an effort to understand the biological relevance of this combinatorial complexity, we characterized their relative expression at a number of developmental time points by parallel in situ hybridization of adjacent tissue sections. Our results reveal that in general there is limited redundancy in the expression of these six transcription factors and that each of these bHLH-PAS members displays a unique pattern of developmental expression emerging as early as embryonic day 9.5.

Animals↗

PubMed1998

The yeast tRNA:pseudouridine synthase Pus1p displays a multisite substrate specificity.

We have previously shown that the yeast gene PUS1 codes for a tRNA:pseudouridine synthase and that recombinant Pus1p catalyzes, in an intron-dependent way, the formation of psi34 and psi36 in the anticodon loop of the yeast minor tRNA(Ile) in vitro (Simos G et al., 1996, EMBO J 15:2270-2284). Using a set of T7 transcripts of different tRNA genes, we now demonstrate that yeast pseudouridine synthase 1 catalyzes in vitro pseudouridine formation at positions 27 and/or 28 in several yeast cytoplasmic tRNAs and at position 35 in the intron-containing tRNA(Tyr) (anticodon GUA). Thus, Pus1p not only displays a broad specificity toward the RNA substrates, but is also capable of catalyzing the pseudouridine (psi) formation at distinct noncontiguous sites within the same tRNA molecule. The cell-free extract prepared from the yeast strain bearing disrupted gene PUS1 is unable to catalyze the formation of psi27, psi28, psi34, and psi36 in vitro, however, psi35 formation in the intron-containing tRNA(Tyr)(GUA) remains unaffected. Thus, in yeast, only one gene product accounts for tRNA pseudouridylation at positions 27, 28, 34, and 36, whereas for position 35 in tRNA(Tyr), another site-specific tRNA:pseudouridine synthase with overlapping specificity exists. Mapping of pseudouridine residues present in various tRNAs extracted from the PUS1-disrupted strain confirms the in vitro data obtained with the recombinant Pus1p. In addition, they suggest that Pus1p is implicated in modification at positions U26, U65, and U67 in vivo.

Cloning, Molecular↗

PubMed1998

Influence of alcohol consumption and various beverages on waist girth and waist-to-hip ratio in a sample of French men and women.

OBJECTIVE: The goal of the present study was to assess the association between alcohol consumption and abdominal fat deposition in France, a country where wine is the most commonly consumed alcoholic beverage. METHODS: We analyzed the association between alcohol consumption and various markers of body weight, in a population sample recruited in three distinct geographical areas of France (MONICA centers). This sample included men (n = 1778) and women (n = 1730) aged 35- 64 y, randomly selected from electoral rolls. Alcohol consumption was assessed with a quantitative frequency questionnaire. RESULTS: Alcohol intake ranged from 0-1655 ml of alcohol per week. Wine was the main source of alcohol, representing 67% of total alcohol intake in both genders. In men, there was no association between alcohol intake and body mass index (BMI) or body weight, whereas in women, alcohol consumption was inversely correlated with BMI (P < 0.0001) and body weight (P < 0.0002). In men, total alcohol consumption was positively associated with waist-to-hip ratio (WHR, P < 0.0002) and waist girth (P < 0.004), independently of BMI. Similarly, in women, positive associations were found between alcohol intake and WHR (P < 0.0001) as well as waist girth (P < 0.0001), independently of BMI. In a linear regression model including types of beverages and usual confounders, reporting consumption of either wine, beer or spirit was poorly associated with WHR in men, whereas wine (P < 0.0008) and beer (P < 0.0001) consumptions were both positively associated with WHR in women. However, there was no evidence of a statistically significant heterogeneous effect of wine, beer and spirits on WHR in both genders. CONCLUSION: In a sample of representative French people, in whom wine is the most common alcoholic beverage, alcohol consumption is associated with greater WHR independently of BMI in both men and women.

Adult↗

PubMed1998

Modelling and simulation of light-activated membrane proteins: dynamical transitions in bacteriorhodopsin.

Many of the functions of membranes are carried out by proteins associated with them. A knowledge of atomic-detail membrane protein structures and dynamics is required for a full understanding of these functions. We briefly discuss recent progress in this field using modelling and simulation. One of the best characterised membrane proteins, bacteriorhodopsin, undergoes dynamical transitions with temperature. Here we present preliminary results of molecular dynamics simulation of this protein as a function of temperature, indicating the presence of dynamical transitions at approximately the temperatures seen experimentally.

Bacteriorhodopsins↗

PubMed1998

[TIPSS: 10 years of clinical experience].

UNLABELLED: To demonstrate and document 10 years of clinical experience gathered by us with TIPSS and to discuss achievements, problems and outlook. MATERIAL AND METHODS: The analysis is based on the following parameters: portosystemic gradient; morphological delineation of the portal circulation; determination of the portal perfusion fraction (PPF) and the total liver perfusion (GLP); arterial flow changes; hepatic encephalopathy; incidence of restenotic shunt occlusion and recurrent variceal bleeding. RESULTS: Variceal filling was widely reduced by TIPSS, and significantly reduced portal liver perfusion as assessed morphologically and rheologically. However, there was an immediate onset of compensated liver perfusion by increased arterial inflow. Total liver perfusion did not change significantly. In TIPSS portal decompression was readily achieved, the portosystemic gradient dropping from an average of 24 mm Hg to 10.5 mm Hg. In our series we could not demonstrate an increased incidence of hepatic encephalopathy during the 30-day post-TIPSS period. Early mortality was 4% and early rebleeding rate 3%. The 12-month re-intervention rate based on an invasive portography follow-up protocol was 76%, and the 24-month re-intervention rate was 90%. The definite occlusion rate was below 5%. Beyond a follow-up time span of 24-months the necessity for re-intervention dropped significantly: less than one-third of our patients required some sort of re-intervention. CONCLUSION: The concept of TIPSS represents an individually calibrated H-shunt. The significant reduction of post-TIPSS portal perfusion appears to be compensated by increased arterial inflow. This is reflected by an invasive flow measurement results and by the clinical results. Lethality of TIPSS is low mostly as a result of a refined technique, careful patient selection, follow-up care and meticulous shunt surveillance.

Hepatic Encephalopathy↗

PubMed1998

An orthotopic floor-of-mouth cancer model allows quantification of tumor invasion.

OBJECTIVES: To establish an orthotopic murine floor-of-mouth cancer model for the analysis of the role of proteases such as urokinase-type plasminogen activator (u-PA) and the matrix metalloprotease MMP-9 (MMP-9) in in vivo invasion. STUDY DESIGN: Randomized, prospective animal study. METHODS: Two human squamous cell carcinoma cell lines, UM-SCC-1 and 022, were assayed via zymography for their in vitro secretion levels of u-PA and MMP-9. Both cell lines (5 x 10(6) cells) were injected into the cervical subcutaneous tissues of female athymic nude (nu/nu) mice superficial to the mylohyoid muscle. Mice were sacrificed after 30 days, and tumor invasion characteristics were histologically compared. Additional mice were then inoculated with invasive UM-SCC-1 cells and sacrificed 10, 30, and 40 days after inoculation to identify distinct stages of invasion. RESULTS: In vitro secretion levels of MMP-9 and activity of u-PA were higher in UM-SCC-1 cells than in 022 cells. In the in vivo studies, tumors formed from 022 cells were found to be noninvasive, whereas tumors derived from UM-SCC-1 cells progressed through distinct and readily identifiable histologic stages of invasion. These stages included invasion of adjacent muscle layers (mylohyoid, geniohyoid, and genioglossus muscles) and of associated structures (blood vessels, bone, nerve, and regional lymph nodes). A staging system was devised accordingly. CONCLUSION: We developed an in vivo quantitative cancer invasion model that allows determination of the effect of the expression and activity levels of the proteases MMP-9 and u-PA. Tumor invasion occurred in an orderly and stepwise fashion involving muscles and related vascular, nervous, and bony structures of the floor of the mouth and tongue. This orderly invasion allowed the development of a staging system. We anticipate that this model will have wide applicability in the study of in vivo tumor response to a variety of novel therapeutic approaches.

Animals↗

PubMed1998

Isolation of Lautropia mirabilis from oral cavities of human immunodeficiency virus-infected children.

Lautropia mirabilis, a pleomorphic, motile, gram-negative coccus, has been isolated from the oral cavities of 32 of 60 (53.3%) children infected with human immunodeficiency virus (HIV) and 3 of 25 (12.0%) HIV-uninfected controls; the association of L. mirabilis isolation with HIV infection is significant (P < 0.001). All children in the study, both HIV-infected children and controls, were born to HIV-infected mothers. The presence of this bacterium was not associated with clinical disease in these children. The HIV-infected children with L. mirabilis did not differ from the HIV-infected children without L. mirabilis in immunological status, clinical status, or systemic medications. The role of HIV infection itself or concomitant factors in the establishment of L. mirabilis in the oral cavity remains to be elucidated.

Child↗