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Biomedical subjects

I Oliva

Publications and source records attributed to I Oliva.

At least 19 recordsLinked to original sources
PubMed2006

Chemical characterization with XPS of the surface of polymer microparticles loaded with morphine.

Hydrophilic matrices are a potentially useful option for the development of oral controlled-release formulations. The porous surface of these particles makes it possible to control or modify release of the active principle after administration. As a result, such formulations can be used in liquid controlled-release pharmaceutical formulations. We investigated a method of spontaneous drug encapsulation to prepare ethylcellulose polymer microparticles (since the polymer is synthetic rather than natural the final suspension is called pseudolatex) filled with morphine hydrochloride. Morphine is incorporated to water during the synthesis process and thus it is microencapsulated inside the micelles that give rise to the final microparticles. X-ray photoelectron spectroscopy (XPS), a technique that can identify elements in a sample without destroying it, was used for the chemical analysis of the surface of these microspheres. The results demonstrated the complete absence of morphine from the microsphere surface, which was taken as evidence that the drug had been completely encapsulated.

Analgesics, Opioid↗
PubMed2002

Sequential atomic force microscopy imaging of a spontaneous nanoencapsulation process.

Since hydrophilic matrices were proposed for controlled drug delivery, many polymeric excipients have been studied in order to make drug release fit the desired profiles. It has been pointed out that lambda-carrageenan, a sulphated polymer from algae, can suitably control the release rate of basic drugs from hydrophilic matrices with no need for complex technological processes. In this work, we propose a method to monitor morphologically the interaction between lambda-carrageenan and dexchlorpheniramine maleate (D-CPM), in order to find out how the release profiles can be so easily controlled. To this end, solutions of both polymer and drug were prepared at very low concentration. Solutions were mixed and samples were taken every hour over a period of 20 h. The characterization technique employed, atomic force microscopy (AFM), provides a high resolution, allowing to show the three-dimensional morphology of the samples within the nanometric scale. The results demonstrate that lambda-carrageenan is able to nanoencapsulate spontaneously D-CPM molecules, which offers the possibility to easily control the release rate of the drug. This work has moreover demonstrated the suitability of AFM for the specific case of the on-time monitoring of interaction processes that happen in pharmaceutical systems.

Carrageenan↗
PubMed2001

Cnr interferes with dimerization of the replication protein alpha in phage-plasmid P4.

DNA replication of phage-plasmid P4 in its host Escherichia coli depends on its replication protein alpha. In the plasmid state, P4 copy number is controlled by the regulator protein Cnr (copy number regulation). Mutations in alpha (alpha(cr)) that prevent regulation by Cnr cause P4 over-replication and cell death. Using the two-hybrid system in Saccharomyces cerevisiae and a system based on lambda immunity in E.coli for in vivo detection of protein-protein interactions, we found that (i) alpha protein interacts with Cnr, whereas alpha(cr) proteins do not; (ii) both alpha-alpha and alpha(cr)-alpha(cr) interactions occur and the interaction domain is located within the C-terminal of alpha; (iii) Cnr-Cnr interaction also occurs. Using an in vivo competition assay, we found that Cnr interferes with both alpha-alpha and alpha(cr)-alpha(cr) dimerization. Our data suggest that Cnr and alpha interact in at least two ways, which may have different functional roles in P4 replication control.

Amino Acid Substitution↗
PubMed1999

[Vasoneuroses].

The term vasoneuroses comprises functional disorders of peripheral vessels, in particular arterioles, manifested by vasospasms on the periphery of the upper and lower extremities, more rarely the nose and ears. The main representant of these diseases is a disorder manifested by episodic attacks of ischaemia of the fingers, in particular of the upper extremities--Raynaud's phenomenon (RP) which has two forms: primary RP (Raynaud's disease) where no other basic disease is diagnoses during a two-year period. secondary RP (Raynaud's phenomenon) as an associated symptom of other, in particular systemic diseases. The etiology and pathology of Raynaud's phenomenon has not been elucidated satisfactorily so far. With regard to the variety and scope of detected functional and morphological abnormalities RP is rather multifactorial, caused by an unbalanced action of local and systemic factors affecting the sensitivity of the vascular wall to spastic stimuli. Treatment therefore remains symptomatic. It is restricted to administration of vasodilatating agents, in more severe cases sympathectomy is considered; it is important to rule out another basic disease. Vasoneuroses include also acrocyanosis, livedo reticularis and erythromelalgia. In the case of erythromelalgia it is important to rule out secondary causes (hypertension and polycythemia vera), otherwise it is not necessary to use pharmacological means to influence these diseases because of their relatively harmless course.

Humans↗
PubMed1991

[Fibrinolytic activity of gingival fluid in hemophiliac patients].

The purpose of this investigation is to compare the fibrinolytic activity in the gingival fluid, of 32 hemophilic patients with 36 normal subjects. Oral examination was carried out in both groups in order to determine the extent of periodontal disease, using the Ramfjord Periodontal Index. The disease was classified in three grades according to the depth of the gingival crevices: grade I: 0 to 3 mm (Normal Deepness); grade II: from 3 to 6 mm; grade III higher than 6 mm. The fibrinolytic activity was measured in fibrin plates, prepared with thrombin and fibrinogen with and without plasminogen. It was found that the fibrinolytic activity was similar in the groups studied and related to the depth of the gingival crevices, with the exception of hemophilic patients with grade I disease, who showed higher fibrinolytic activity in the fibrin plates with plasminogen, than in the corresponding controls (p less than 0.001). This result could possibly be due to mucosal traumatism during the withdrawal of the sample, which permitted the release of plasminogen activators from the damaged vessels. It is important to mention the absence of grade III periodontal disease in the hemophilic group. The reason for this result could be due to the important bleeding occurring in grade II, which induces the patient to seek immediate professional attention. The above mentioned results suggest that the fibrinolytic activity of the gingival fluid in hemophilic and control patients is directly related to the degree of periodontal disease.

Adult↗
PubMed1989

The effect of hydroxyethylrutoside and its combination with acetylsalicylic acid in patients with obliterative atherosclerosis.

The effect of 7-mono-hydroxyethylrutoside and its combination with acetylsalicylic acid was evaluated in a controlled clinical trial, performed in 105 patients with obliterative atherosclerosis of the lower limbs, and using non-invasive measurement of peripheral haemodynamic parameters--blood flow during reactive hyperaemia and ankle systolic blood pressure. Patients, randomized into three groups, received either placebo or 7-mono-hydroxyethylrutoside alone or in combination with acetylsalicylic acid for 12 months. The placebo group showed a decrease in maximum calf blood flow and a decrease in ankle systolic pressure. Administration of 7-mono-hydroxyethylrutoside did not lead to any significant changes in systolic pressure but there was a decrease in the maximum calf blood flow. There were no statistically significant changes in patients receiving the 7-mono-hydroxyethylrutoside and acetylsalicylic acid combination who, by contrast, showed a tendency to increased values of the parameters measured.

Adult↗
PubMed1989

[Comparison of humeral blood flow during rewarming and recooling of the hand in normal subjects or presenting Raynaud's phenomenon].

Vascular reactivity to heat and cold was studied in 11 normal subjects without vascular disease and in 23 patients with Raynaud's phenomenon (etiologies: Raynaud's disease, scleroderma, thoracic outlet syndrome). The study of hand and digital temperatures and brachial artery blood flow was performed in ambiant conditions (room temperature 23.5 +/- 1 degree C) and after thermal (cold or warm exposure: 10, 33 and 40 degrees C), mechanical and metabolic modifications (with a wrist tourniquet). In these conditions, blood flow was studied at each temperature, before, during and after 3 minutes ischemia of the hand. Analysis of results showed that vasomotricity possibilities were preserved but that responses were not identical. Patients with primary Raynaud's phenomenon, and even more those with scleroderma as well, had reduced brachial artery blood flow after cooling (10 degrees C). After ischemia, maximal blood flow was also reduced. The microcirculatory disease existing in Raynaud's phenomenon limits the vasodilator capacity of hand vessels, but probably more in tissues with vascular lesions. Vasodilation seems to be limited during exposure to low well as high temperatures, but vasoconstriction capacity is not disturbed.

Adult↗
PubMed1989

Blood flow through the brachial artery at different temperatures in patients with Raynaud's phenomenon.

Blood flow through the brachial and radial artery at different temperatures and during reactive hyperaemia was measured in 23 patients with Raynaud's phenomenon (9 patients with Raynaud's disease, 7 - Raynaud's syndrome with thoracic outlet syndrome (TOS), and 8 - Raynaud's syndrome and scleroderma), and 11 control subjects. Blood flow was determined by an ALVAR pulse-wave Doppler system enabling measurement of vessel diameter and blood flow rate. The measurements suggest that the blood flow through brachial artery reflects the changes of blood flow through the hand immersed in water of different temperatures. Maximum vasoconstriction was the same in all groups of Raynaud's phenomenon. The lowest blood flow at higher temperatures and during reactive hyperaemia was found in patients with scleroderma, whereas in the group of TOS and partly in patients with Raynaud's disease one can suspect only functional changes.

Adolescent↗
PubMed1986

Capillary filtration coefficient in the forearm of patients with essential hypertension.

The capillary filtration coefficient (CFC) in the forearm was followed in patients with essential hypertension and compared with controls, using the method of venous occlusion plethysmography and simultaneous recording of intravenous pressure in the measured segment of the extremity. Arterial blood-pressure was obtained in the contralateral arm by auscultation. The CFC averaged 0.0039 +/- 0.009 ml/100 ml/min/mmHg and 0.0095 +/- 0.0018 ml/100 ml/min/mmHg in hypertensives and controls respectively. The relation between CFC and arterial blood-pressure values was inversely non-linear. The results suggest reduction of the capillary area due to hypertension and possibly functional or structural changes in the microcirculatory bed accompanying systemic blood-pressure increase.

Adult↗
PubMed1983

Transcapillary escape rate of albumin in juvenile hypertension.

The transcapillary escape rate of albumin was studied in 24 juvenile hypertensives and in 13 controls on the basis of the radioactivities determined in the blood during 60 min after i.v. injection of human 131I-labelled albumin. In addition, the central haemodynamics of all hypertensive subjects was examined at rest and during exercise. The patients were grouped according to their pressure during the investigation at rest. The group whose mean arterial pressure did not exceed 100 mmHg, thus being within the range of normotension, did not exhibit a significant deviation from controls. The group with mean arterial pressure exceeding this limit (corresponding to the range of borderline hypertension) showed a significantly higher escape rate of albumin (9.3 +/- 5.0%/h) than controls (5.2 +/- 1.6%/h). The albumin escape rate was significantly correlated to the mean pulmonary artery pressure during exercise but not to the remaining central haemodynamic parameters at rest or during exercise. No difference was seen in the magnitude of plasma volumes of juvenile hypertensives and controls. The findings suggest that secondary changes of capillary functions are present already in the early stages of hypertension.

Adult↗
PubMed1983

Toe pulse wave analysis in obliterating atherosclerosis.

photoplethysmographic measurements were carried out in 61 limbs with angiographically documented obliterating atherosclerosis (OA) and in 72 limbs with OA. The distance P was measured between the ascending and descending limbs of the pulse wave at the border of the upper and middle thirds of the amplitude. To standardize the measurements the P value was divided by the length L of the pulse wave (P/L ratio). Using 95% confidence limit in the group of healthy young individuals, 80.8% of the lower limbs with obliterating atherosclerosis without occlusion (OAWO) and 100% of those with complete occlusion (OAWCO) were revealed. In the group of healthy individuals (average age 50 years), 69.8% of lower limbs with OAWO and 100% of those with OAWCO were found. This method showed the higher number of detected OAWO when compared with peripheral systolic pressure measurements.

Adult↗
PubMed1980

Instaneous changes in the radial artery blood flow under different physiological conditions.

Using a Doppler pulse flowmeter we measured the blood flow in the radial artery at rest and during physical exercise and various other stimuli (arithmetical calculations, electrical stimulation, deep inspiration). The mean resting flow in the radial artery was 0.66 ml/s. Every stimulus was instantaneously followed by a drop in the blood flow to a minimum value; there was no significant differences between these values. The results demonstrate that the new, non-invasive apparatus can be used to study quick changes in the blood flow not detected by routine non-invasive methods.

Adult↗
PubMed1980

Assessment of capillary functions in man.

Capillary functions in humans can be assessed by measuring capillary filtration and capillary diffusion capacity in the extremities. Examination of these two parameters supplements each other and renders it possible to evaluate capillary function from different aspects. As an example of practical use may serve the findings in patients with obliterating atherosclerosis of the lower extremities and in subjects with chronic venous insufficiency. The authors revealed a rised capillary diffussion capacity on obliterated extremities and a reduced capillary filtration in venous insufficiency. It is possible that in both instances these are manifestations of adaptational changes focused on the prevention of oedema formation and on a raised metabolism under conditions of an inadequate blood supply of tissues.

Arteriosclerosis↗