PubMed Health⌕ Search

Biomedical subjects

A Biron

Publications and source records attributed to A Biron.

At least 19 recordsLinked to original sources
PubMed2004

Search for extraterrestrial point sources of neutrinos with AMANDA-II.

We present the results of a search for point sources of high-energy neutrinos in the northern hemisphere using AMANDA-II data collected in the year 2000. Included are flux limits on several active-galactic-nuclei blazars, microquasars, magnetars, and other candidate neutrino sources. A search for excesses above a random background of cosmic-ray-induced atmospheric neutrinos and misreconstructed downgoing cosmic-ray muons reveals no statistically significant neutrino point sources. We show that AMANDA-II has achieved the sensitivity required to probe known TeV gamma-ray sources such as the blazar Markarian 501 in its 1997 flaring state at a level where neutrino and gamma-ray fluxes are equal.

Journal Article↗
PubMed2003

Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector.

Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon neutrinos. This search yielded no excess events above those expected from background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux measured at the earth. For an assumed E-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E2Phi(E)=8.4 x 10(-7) cm(-2) s(-1) sr(-1) GeV (for a predominant neutrino energy range 6-1000 TeV), which is the most restrictive bound placed by any neutrino detector. Some specific predicted model spectra are excluded. Interpreting these limits in terms of the flux from a cosmological distributions of sources requires the incorporation of neutrino oscillations, typically weakening the limits by a factor of 2.

Journal Article↗
PubMed2003

Image guided navigation system-a new technology for complex endoscopic endonasal surgery.

PURPOSE: Endoscopic endonasal surgery (EES) has become the standard practice in sinonasal and anterior skull base surgery. The purpose of this manuscript is to describe experience using a new technology-the image guided navigation system (IGNS)-in complex cases undergoing EES. The advantages and disadvantages of computer aided surgery are discussed. PATIENTS AND METHODS: A total of 165 endoscopic endonasal procedures were performed between April 2001 and January 2003. IGNS was used in 34 patients in whom it was assumed that the ability to identify surgical sites accurately could be compromised by previous surgery, massive recurrent polyposis, or abnormal anatomy, or when biopsies had to be taken from specific anatomic locations (for example, clivus, wall of sphenoid sinus, orbital apex). The precision of the navigation system, total operating room time, surgeon's satisfaction and confidence, and intraoperative and postoperative complications were recorded. RESULTS: In 33 out of 34 patients the surgical procedure was uneventful. One patient with an atelectatic maxillary sinus developed a minor complication of preseptal orbital haematoma. In 94% the IGNS provided accurate anatomical localisation with less than 2 mm localisation error (1.1-2.0 mm, mean 1.6 mm). In all cases the surgical team felt that the system increased the intraoperative safety factor for the patient. The overall operating room time at the end of the study was 15 minutes longer than when regular EES was used. CONCLUSIONS: IGNS enables a new level of efficiency and safety in EES. Nevertheless, it is not advised for surgeons who are not familiar with regular EES. For the experienced endoscopist, however, IGNS is a valuable new tool in complex procedures.

Adult↗
PubMed2001

Observation of high-energy neutrinos using Cerenkov detectors embedded deep in Antarctic ice.

Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water or ice. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations.

Journal Article↗
PubMed2000

Seasonal variation in sudden death in the Negev desert region of Israel.

BACKGROUND: Previous studies have documented an increased incidence of cardiac mortality and sudden death during winter months. OBJECTIVES: To evaluate seasonal variation in sudden death in a hot climate such as the desert region of southern Israel. METHODS: We analyzed the files of 243 consecutive patients treated for out-of-hospital sudden death by the Beer Sheva Mobile Intensive Care Unit during 1989-90. Daily, monthly and seasonal incidence of sudden death was correlated with meteorological data, including temperature, heat stress, relative humidity and barometric pressure. RESULTS: The seasonal distribution of sudden death was 23% in spring, 21% in summer, 25% in autumn and 31% in winter (not significant). In patients with known heart disease there were more episodes of sudden death in cold weather (< 15.4 degrees C) than hot (> 34.2 degrees C) (16 vs. 3, P < 0.05). Resuscitation was less successful in cold compared with hot weather (28 vs. 11, P < 0.05). Of patients older than 65 years, 11 sustained sudden death when heat stress was below 12.4 degrees C compared to 2 patients when heat stress was above 27.5 degrees C (P = 0.05). CONCLUSION: Despite the warm desert climate, there were more cases of sudden death in older patients and in those with known heart disease during the winter season and on particularly cold days.

Adult↗
PubMed1984

Prognostic factors and indications for surgical treatment of acute aortic dissections: a report based on 191 observations.

A total of 191 acute aortic dissections were examined to define prognostic factors for surgical intervention. Overall survival rate reached 40% in the 94 patients operated upon and 8% in the 97 patients not operated upon. Among the 122 patients with involved ascending aorta, survival rate was 2% in the 42 nonoperated patients versus 42% in 80 patients undergoing surgery. Since 1977, overall survival rate has reached 60% in the surgical group (21 of 35 patients) and 20% in the nonsurgical group (5 of 25 patients). Factors that showed a significant correlation with postoperative death include: persistent shock; persistent anuria; persistent neurologic deficit; diffuse intravascular coagulation; and involvement of either the celiac trunk, superior mesenteric artery, or both renal arteries at angiography. With the exception of those patients exhibiting any of these high-risk factors, emergency surgical treatment is recommended for all dissections that involve the ascending aorta.

Adult↗
PubMed1983

Life expectancy following spinal cord injury: a ten-years survey in the Rhône-Alpes Region, France, 1969-1980.

A ten years survey of 848 patients having sustained traumatic spinal cord injury between 1969 and 1979 was conducted in the Rhône-Alpes Region, France. All patients had been referred to the spinal cord injury unit, Hôpital Henry Gabrielle. 48 deaths were recorded: 36 patients admitted early to the Unit, and 12 patients injured before 1969 but followed-up in the Unit. The deceased patients were older and more frequently male and tetraplegic than the rest of the group. In 75 per cent of the deceased patients, the survival time was less than 1/5 of the theoretical life expectancy. In 59 per cent, it was less than 1/10. Twenty tetraplegics died of respiratory complications. Three patients committed suicide, the rest died of urinary complications. The results appear to determine a secondary period with high mortality rate, after the initial high mortality of these patients. About one year post-injury, the life expectancy in our series appears to tend towards the values observed in the French population.

Adolescent↗
PubMed1981

[Stenosis of the left main coronary artery. Results of aorto-coronary by-pass in 67 patients (author's transl)].

Between 1970 and 1978 sixty-seven patients with > 50% stenosis of the left main coronary artery underwent aorto-coronary by-pass operation. The mean follow-up period was 54.7 months. Early and late post-operative mortality rates amounted to 3% and 9.2% respectively. Severe global alteration of left cineventriculography was the primary factor of survival (p < 0.01). The actuarial survival rates were 90.3% at 5 years and 84.5% at 9 years. All survivors had control ECGs. Late myocardial necrosis was rare (0.6 per 100 patient-years). 60.3% of the patients remained free from angina. Deterioration of the results mainly occured during the first 2 years but continued at a slower pace beyond the 8th year. Recurrence of angina was significantly less frequent in patients with isolated left main stenosis (p < 0.05) and when local conditions were not unfavourable to derivative surgery (p. < 0.01). On the other hand, the patient's age, sex, type of angina, history of previous infarction, number of risk factors and number of by-passes (the latter excluding possibly incomplete revascularisation) has no influence on the functional prognosis. Thirty-two patients had control, usually routine coronary arteriography 13.7 months on average after surgery. Overall patency was found in 85.9% and abnormal grafts in 16.7% of the cases. The main benefits of aorto-coronary by-pass, therefore, were a reduction in the spontaneous mortality rate of patients with left main coronary disease and a pronounced functional improvement.

Adult↗
PubMed1981

[Coronary bypass surgery. Results after 5 years : mortality - morbidity].

The improvement in the expectation and quality of life of patients undergoing coronary bypass surgery has been studied in the short term but there are relatively few studies with follow-up periods of over five years. The results in 239 patients operated on between 1970 and 1976 are presented. The preoperative data was obtained from a computerised filing system; studies were made at 3 months, at an average of 60 months, and in 78 patients with follow-up exceeding 5 years. Actuarial survival rates were calculated. The operative mortality was 9 patients (3,7%); late mortality was 21 patients (9,2%). Most deaths were due to cardiac causes. The following factors did not appear to be associated with a poor prognosis: sex, the number of cardiovascular risk factors, the number of bypass grafts; however, age and poor left ventricular function as identified by ECG (p less than 0,01), the presence of clinical cardiac failure (p less than 0,001) and by angiography (p less than 0,001) were associated with a poor prognosis. The long-term functional results were interesting: 67% patients followed up to 5 years and 56% patients followed up for over 5 years had no angina. Myocardial infarction occurred in 16,7% of patients at 5 years. Preexisting left ventricular failure which affected the operative and immediate postoperative results was also found secondarily in 9% of patients at 5 years. In the long term, the annual mortality rate seemed to be less in patients with triple vessel disease after myocardial revascularisation. The annual mortality rate of patients with left anterior descending disease alone did not seem to be improved when compared with medically treated patients until after the third year. Once again, the extent of myocardial disease was shown to be the essential prognostic factor whatever the coronary profile of the patient. In this study patients with severe angina or unstable angina who had been treated medically before surgery had the same results as those treated surgically by first intention; this fact is an argument in favour of initial medical management in all forms of angina.

Adult↗
PubMed1981

[Prognosis following mitral valve replacement with the Starr-Edwards 6120 prosthesis].

Between 1970-78, 302 mitral valve replacements with the SE 6120 prosthesis were performed, with an average postoperative follow-up of 50,7 months, using the 3 M size (206 cases) and 2 M (96 cases with small left ventricles). Early postoperative mortality was 5,6%, late postoperative mortality: 17,2%, the 5 year actuarial survival rate: 77,4% and the 9 year survival rate 71,8% (early mortality included). There was no significant difference in survival after mono- (143 cases) and polyvalvular replacement (159 cases); only a voluminous left atrium (p less than 0,05) and left atrial thrombosis (p less than 0,01) were statistically significant prognostic factors of global mortality. Late haemorrhage due to anticoagulant therapy (3%) (0,6 per 100 patient years). The most common complication was systemic embolism (3,7 per 100 patient years). Actuarial studies showed that 86,6% at 5 years and 80,1% at 9 years, escaped this complication. Statistically the favorising roles of permanent atrial fibrillation (p less than 0,05), the size of the left atrium (p less than 0,02) of isolated demonstrated. 90,4% of the survivors were clinically improved: the functional result was better when that 86,6% at 5 years and 80,1% at 9 years, escaped this complication. Statistically the favorising roles of permanent atrial fibrillation (p less than 0,05), the size of the left atrium (p less than 0,02) of isolated demonstrated. 90,4% of the survivors were clinically improved: the functional result was better when that 86,6% at 5 years and 80,1% at 9 years, escaped this complication. Statistically the favorising roles of permanent atrial fibrillation (p less than 0,05), the size of the left atrium (p less than 0,02) of isolated demonstrated. 90,4% of the survivors were clinically improved: the functional result was better when the valve replacement was not a reoperation (p less than 0,02), when the patient was not in functional Class IV (p less than 0,01), in permanent excessively dilated (p less than 0,01) and in patients without severe tricuspid regurgitation (p less than 0,01). There was no significant difference in global mortality, the percentage of embolic events and the quality of the functional postoperative result between patients with the 3 M and those with the 2 M SE 6120 prosthesis.

Adult↗
PubMed1980

[Operable carcinoma of the breast. Prognostic value of estradiol receptors. Preliminary report (author's transl)].

151 women were treated for potentially curable breast cancer. Their tumors were routinely analysed for estrogen receptors by the dextran-coated charcoal technic. Data were analyzed in relation to several parameters: age, age of menstruation, menopausal status, tumor size, TNN staging, axillary node status, nature of treatment. We have examined the pronostic implication of an ER negative content (ER-) in the primary tumor. We have found that the absence of detectable estrogen receptor in primary breast tumor appears to be correlated with a short disease free interval. In positive axillary node patients the value of the disease free interval is significantly shorter in ER- than in ER+ group: 11.5 months versus 23.5 (p less than 0.01).

Adult↗
PubMed1980

[Prognosis of primary non-obstructive cardiomyopathies].

The prognosis of congestive cardiomyopathy was studied in 132 consecutive patients (110 male, 22 female, average age 45 +/- 11 years) in whom a thorough clinical evaluation had excluded a secondary cause. The patients presented with left ventricular failure, a history of systemic embolism, syncope or radiological cardiomegaly. Right (100 p. 100) and left (81 p. 100) heart catheterisation was performed and left ventricular endiastolic volumes (202 +/- 77 ml/m2) and ejection fractions (31 +/- 12 p. 100) calculated from angiography in the 30 degrees right anterior oblique projection. Regional abnormalities of contraction were observed in 32 patients. The average follow up period was 40,4 +/- 23,8 months. At the end of the study 48 patients (37 p. 100) had died and 2 had been lost to follow up. Survival rates were calculated by actuarial methods. Age, sex, the period they had been symptomatic, alcoholic intoxication and the degree of cardiac dilatation were not significant prognostic factors. Patients in Class IV NYHA had the worst prognosis: 63 p. 100 2 year mortality. Atrioventricular conduction defects were observed in 56 patients and were associated with a significantly increased mortality rate (43 p. 100 compared with 23 p. 100, p < 0.001). Atrial fibrillation (32 patients) was a better prognostic factor than the persistence of sinus rhythm; 2 year mortality 11,1 p. 100 compared to 37,6 p. 100 (p < 0.001). Increased left ventricular end diastolic pressures greater than 20 mmHg were related with a mortality of 51,5 p. 100. Also, the patients with a ejection fraction of 30 p. 100 and a 2 year mortality rate of 44 p. 100 compared to 17,5 p. 100 when the ejection fraction was greater than 30 p. 100 (p < 0,001). In conclusion : 1. Regional abnormalities of left ventricular contraction are not rare in primary cardiomyopathy. 2. The prognosis is directly related to the degree of cardiac failure and the extent of left ventricular dysfunction.

Adolescent↗
PubMed1980

[Puberty in congenital hypothyroidism (author's transl)].

Puberty was studied in 95 patients with congenital hypothyroidism treated between 1953 and 1977 from the first months or first year of life. Pubertal abnormalities were observed in 13 cases: 1. Delayed puberty in 11 cases (late diagnosis in 6 cases, insufficient treatment in 2 cases, delayed puberty in the family in 1 case). 2. An amenorrhea-galactorrhea syndrome was observed in two cases with insufficient treatment. In the other cases, the outcome of puberty seemed within the normal range. However a careful study showed: 1st. A delay of every stage of puberty, 2nd. The absence of the peak of high velocity in some cases. 3rd. The age of menarche was 13 years 8 months (9 years 1 month-16 years 6 months) (normal girls: 13 years). Final height was dependent upon an early and efficient treatment, and upon a fast catch up of growth and bone maturation.

Adolescent↗