PubMed Health⌕ Search

Biomedical subjects

C Constantin

Publications and source records attributed to C Constantin.

At least 19 recordsLinked to original sources
PubMed2005

[Considerations regarding Goldmann's rheologic equation].

PURPOSE: The aim of this paper is to verify if Goldmann's rheological concept is still valid. That is because the validity of this concept has been contested. (Beneyto P., Fernandez-Vila P.C., Perez T.M--An experimental approximation to the law of Goldmann: study of the dynamics of the aqueous humor outflow. Ann. Ophthalmol. Glaucoma, 1995, 27, 3, 160-166, Abstract in Glaucoma abstracts 1995, Vol. 6, nr. 3, 63.) MATERIAL: The authors sustained that Goldmann's equation has never been verified. On 42 normal eyes and 54 glaucomatous eyes (POAG) they determined aqueous flow by fluorophotometry, IOP by aplanotonometry and considered a value of 9mmHg as normal episcleral veins pressure. The results they obtained showed that in 47% of the cases the fluorophotometric values were with over 1microl/min higher then the calculated values using Goldmann's equation. So, they concluded that Goldmann's equation could be wrong. METHOD: There are two outflow pathways for the aqueous humor, trabecular and uveoscleral. Obviously, the uveoscleral outflow (Fu) summed with the trabecular outflow (Ftr) must be equal with the aqueous flow (FIN), and the total outflow facility (CTRU) must be the sum of the trabecular outflow facility (Ctr) and uveoscleral facility (Cu). Thereby Goldmann's equation can be written: FIN = Ftr + Fu = (Pio-Pv) * CTRU and Ftr = (Pio-Pv) * Ctr, Fu = (Pio-Pv) * Cu. With the authors' data we verified the previous equations. RESULTS: There is correspondence between clinical and mathematically deducted parameters. CONCLUSIONS: 1. Goldmann's rheological concept is still valid. 2. With proper modifications Goldmann's equation is still valid.

Algorithms↗
PubMed2004

Observation of the parametric two-ion decay instability with thomson scattering.

We present the first direct experimental observation of the parametric two-ion decay instability of ion-acoustic waves driven by a high intensity (5 x 10(15) W cm(-2)) laser beam in a laser produced high-Z plasma. Using two separate Thomson scattering diagnostics simultaneously, we directly measure the scattering from thermal ion-acoustic fluctuations, the primary ion waves that are driven to large amplitudes by the high intensity beam, and the two-ion decay products. The decay products are shown to be present only where the interaction takes place and their k spectrum is broad.

Journal Article↗
PubMed2004

Efficient multi-keV X-ray sources from Ti-doped aerogel targets.

We have measured the production of hnu approximately 4.7 keV x rays from low-density Ti-doped aerogel (rho approximately 3 mg/cc) targets at the OMEGA laser facility (University of Rochester), with the goal of maximizing x-ray output. Forty OMEGA beams (lambda(L)=0.351 microm) illuminated the two cylindrical faces of the target with a total power that ranged from 7 to 14 TW. The laser fully ionizes the target (n(e)/n(crit)</=0.1), and a laser-bleaching wave excites, supersonically, the high-Z emitter ions in the sample. Ti K-shell x-ray emission was spectrally resolved with a two-channel crystal spectrometer and also with a set of filtered aluminum x-ray diodes; both instruments provide absolute measurement of the multi-keV x-ray emission. We find between 40 and 260 J of output with 4.67</=hnu</=5.0 keV.

Journal Article↗
PubMed2001

The in vitro effect of a low molecular weight heparin, nadroparin (Fraxiparine), on leukocytes obtained from patients with vascular diseases.

BACKGROUND: Both lymphocytes and granulocytes may play a role in the immune system-mediated inflammatory response associated with non-Q wave infarction and aortic aneurysms. METHODS: The purpose of this study was to establish the in vitro effects of a low molecular weight heparin (LMWH), nadroparin (Fraxiparine), on some functional parameters of peripheral granulocytes and lymphocytes isolated from control subjects and patients with aortic aneurysm or non-Q wave infarction. RESULTS: Nadroparin (0.06-600 AXaU/ml) exerted different in vitro effects on granulocytes and lymphocytes isolated from normal subjects and the patient groups. The following indices were assessed: superoxide anion release, lymphocyte proliferation, phagocytic activity and the cellular respiratory burst. The effects of nadroparin varied according to the patient group and the index of lymphocyte/granulocyte assessed. CONCLUSIONS: Since peripheral granulocytes isolated from these patients are activated, the observed inhibition exerted by nadroparin on superoxide anion release may be beneficial. LMWHs have additional effects that are independent of their anticoagulant activity. These effects may influence the "inflammatory component" of the atherosclerotic process.

Aged↗
PubMed2000

Shaping of intense ion beams into hollow cylindrical form

A specifically tailored plasma lens could shape a high-energy, heavy-ion beam into the form of a hollow cylinder without loss of beam intensity. It has been experimentally confirmed that both a positive as well as a negative radial gradient of the current density in the active plasma lens can be the underlying principle. Calculations were performed that yield the ideal current density distribution for both cases. A numerical simulation of an experiment with an intense ion beam highlights that the shaping of the beam increases the achievable compression in a lead sample.

Journal Article↗
PubMed2000

Incorrect echocardiographic diagnosis in patients with mechanical prosthetic valve dysfunction: correlation with surgical findings.

PURPOSE: To identify the rate of occurrence and type of incorrect echocardiographic diagnoses in patients with mechanical valve prostheses. PATIENTS AND METHODS: We studied 170 consecutive patients (73 women and 97 men) with a total of 208 prostheses who underwent surgery for mitral (n = 136) or aortic (n = 72) valve dysfunction between January 1991 and December 1997. Preoperative echocardiographic data were compared with surgical findings. Any major discrepancy between the echocardiographic reports and surgery was judged to be unconfirmed when the preoperative echocardiographic diagnosis was not confirmed at surgery, but the prosthesis was found to be dysfunctioning; and was judged to be erroneous when the preoperative echocardiographic diagnosis was not confirmed, and surgical inspection failed to reveal any other prosthetic abnormality. RESULTS: There were 25 (12%) diagnostic errors. Of the 136 mitral prostheses, there were 9 unconfirmed diagnoses of paravalvular regurgitation (6 had a fibrous tissue overgrowth, 1 had a thrombus with fibrous tissue overgrowth, 1 had endocarditis vegetations, and 1 had a ball variance) and 5 erroneous diagnoses. Eleven diagnostic errors were made in the 72 aortic prostheses: there were 9 unconfirmed diagnoses (paravalvular regurgitation was diagnosed as transvalvular in 7, and transvalvular regurgitation as paravalvular in 2 cases), and 2 erroneous diagnoses. CONCLUSIONS: Although echocardiography has gained great credibility among clinicians, special care should be taken when assessing patients in whom prosthetic valve dysfunction is suspected.

Aged↗
PubMed2000

[Erythema migrans with multiple lesions].

INTRODUCTION: Erythema migrans with multiple lesions is observed in Europe in only 5-20 p. 100 of Borrelia infections. The number of lesions observed simultaneously in one patient is less than 7, considering all the cases published in the literature to date. CASE REPORTS: We report three patients who presented multiple macular, erythematous and centrifugal lesions localized on the trunk and the limbs. The first patient presented about thirty lesions, the second more than seventy, and the third about twenty. Serology investigation and immunoblots allowed to establish the diagnosis of a recent Borrelia Burgdorferi infection, with multiples lesions of erythema migrans. PCR performed on a skin biopsy of one of the patients confirmed the presence of Borrelia burgdorferi. Response to antibiotic therapy was immediate in all 3 patients. DISCUSSION: These 3 cases are of particular interest because the number of simultaneous lesions is much higher than what is reported in the European literature. These observations remind the clinician that the diagnosis of erythema migrans with multiple lesions should be included, in Europe as well, in the differential diagnosis of multiple annular dermatoses.

Adult↗
PubMed1999

[Ocular manifestations in Recklinghausen's disease].

Four cases of Recklinghausen disease are presented with different clinical manifestations. The diagnosis in each case was established on NIH Consensus Statement criteria. The last case is a controversial one concerning the type of neurofibromatosis.

Adult↗
PubMed1999

[Modern pathogenetic-therapeutic approaches in glaucoma].

The review presents briefly the new orientations in pathogenically research of glaucoma, the actual theory of apoptosis in generating glaucomatous neuropathy. The substances and transmitters that interfere in the process of apoptosis are also discussed. It is also discussed the new neuroprotective medication. The conclusion is that this new therapy will be an adjunctive one to the classical antiglaucomatous therapy.

Apoptosis↗
PubMed1998

[Influence of sex on reporting pain].

In many epidemiological pain studies, women more frequently report more intense, frequent and long-lasting or chronic transient pain than men. In our retrospective study including hospitalised patients referred to a pain centre, prevalence of headaches, musculoskeletal pain and somatoform pain was observed in women, as described in the literature. Generally pain intensity was higher in women and pain was more frequently controlled in men, but when intensity and pain control were compared according to the pain aetiologies, no gender difference was found. Drug treatments were adapted to pain aetiologies, which accounted for the observed differences. In hospitalised patients the significant differences observed in intensity, pain control and treatment reflect the heterogeneity of pain aetiologies rather than gender differences.

Adult↗
PubMed1998

Norwegian scabies in a patient with acquired immunodeficiency syndrome.

We report the case of a 42-year-old man with symptomatic HIV infection (C3 CDC stage) who presented widespread hyperkeratotic skin lesions diagnosed as Norwegian scabies. The CD4 count was 87 cells/mm3. The patient has been the source of a nosocomial outbreak (20 individuals affected). He was treated successfully with combined topical treatment (permethrin 5% cream plus keratolytic agents) and oral ivermectin.

Acquired Immunodeficiency Syndrome↗
PubMed1994

[Predictive factors of resistance to treatment of neuropathic pain].

The aim of this retrospective study was to examine factors related to symptomatic pain treatment in 992 hospitalized patients referred to the pain clinic. These patients accounted for 1440 different pains (1.5 pains/patient), of nociceptive (59%), or neuropathic (24%) origin, a combination of both (16%) and of unidentified (1%) origin. Patients resistant to therapy did not differ from nonresistant patients (62%) in terms of age, sex, or number of pains. Although recommended pharmacological treatments were pursued, the neuropathic origin of pain was a factor in resistance to treatment. Among the neuropathic pains resistant to treatment (42%) a central nervous origin is more frequently found. Resistance to pain was more frequently encountered after strokes, primitive tumor of the central nervous system or traumatic plexopathy, whereas peripheral lesions of the nervous system were more easily controlled by symptomatic treatment. This study shows that central neuropathic pain is more frequently associated with resistance to recommended pharmacological symptomatic treatments. This observation underlines the limits of conventional medical therapy.

Analgesia↗
PubMed1981

Ultrastructural changes of the hypertrophic epithelial cells in the thymus of splenectomized chickens.

Three weeks following the splenectomy of young chickens an increased number of the hypertrophic epithelial cells, which presented various signs of secretory activity, could be observed in the thymus. After splenectomy, these cells usually present a single, large-sized intracytoplasmic vesicle or vacuole lined with microvilli. The lumen of such vesicles is always full of granulated and membranous material. The ultrastructural appearance of the hypertrophic epithelial cells strongly suggests an intensive metabolic activity and a possible active protein synthesis. These results lead to the hypothesis that hypertrophic epithelial cells secrete a lymphopoietic hormones which is active in normal chickens and which is secreted at an accelerated rate during certain hyperfunctional circumstances such as the period following splenectomy.

Animals↗