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Biomedical subjects

R Munoz

Publications and source records attributed to R Munoz.

At least 37 records · Page 2Linked to original sources
PubMed1992

Intraocular irrigating solutions and vitrectomy-related changes (in protein, lactic and ascorbic acid) in rabbit vitreous.

Vitrectomy and the subsequent vitreous fluid exchange alter the chemical and physical properties of the vitreous. This study assessed the time course alterations of total protein, ascorbic acid and lactic acid in the rabbit vitreous cavity following vitrectomy. Normal values were 2.2 +/- 1.2 mg/ml, 8.5 +/- 1.0 mg/100 ml and 16.8 +/- 3.5 mumol/ml, respectively. Nine groups of 5-10 adult albino rabbits underwent closed vitrectomy using physiologic saline, Ringer's lactate and BSS plus solutions. Samples were withdrawn at 3 and 24 h and 7 days after vitrectomy. Total protein levels increased in all groups at 3 and 24 h (20-30 mg/ml). Ascorbic acid measurements at 24 h rose only with saline and BSS plus. At 24 h the BSS plus group was the only one demonstrating an increased lactic acid concentration.

Animals↗
PubMed1992

Selective inhibition of the contractile apparatus. A new approach to modification of infarct size, infarct composition, and infarct geometry during coronary artery occlusion and reperfusion.

BACKGROUND: Myocardial reperfusion is associated with calcium overload and cell contracture, mechanisms that may precipitate cell death. In this study, we tested the hypothesis that in vivo inhibition of this contracture could lead to cell preservation in an open-chest large animal model. METHODS AND RESULTS: Regional myocardium function was measured during a selective intracoronary infusion of 2,3-butanedione monoxime (BDM), a specific inhibitor of actin-myosin coupling, in the control state (10 pigs) and in a protocol of a 51-minute coronary occlusion followed by reperfusion (40 pigs). The effects on coronary artery blood flow in the basal state were also studied (seven pigs). Intramyocardial distribution of the infusate during coronary occlusion, myocardial water content after 30 minutes of reperfusion and area at risk, infarct size, type of histological necrosis, and infarct geometry after 24 hours of reperfusion were assessed. Methods used included electromagnetic flowmeter, radiolabeled microspheres, subendocardial sonomicrometers, fluorescein, triphenyl tetrazolium chloride and Masson's trichrome staining, and computer quantification of infarct edges. In the absence of ischemia, BDM infusion inhibited regional shortening in a dose-dependent manner up to full systolic bulging while producing marked regional increase in coronary blood flow. During early reperfusion, BDM reduced end-diastolic length 76% more than the control infusion (p less than 0.05) and increased systolic bulging by 420% compared with no change in control animals. The ratio of infarct size/area at risk was reduced by 31% with BDM (p less than 0.05), with striking modifications of infarct histology and infarct geometry; specifically, the extent of contraction band necrosis was reduced by 63% from 105.5 +/- 18.2 to 39.2 +/- 13.6 mm2 (p less than 0.02), and more patches of necrosis (6.5 +/- 2.1 versus 1.6 +/- 0.4, p less than 0.05) and higher contour (7.7 +/- 1.2 versus 5.03 +/- 0.2, p less than 0.05) and fractal (12.1 +/- 1.3 versus 7.8 +/- 0.2, p less than 0.05) indexes were found. CONCLUSIONS: Selective intracoronary infusion of BDM at doses inhibiting regional wall motion decreased infarct size after reperfusion. The effects of BDM on regional function, the reduction in contraction band necrosis at histology, and the peculiar configuration of these infarcts all suggest that inhibition of contracture can interfere with cell-to-cell progression of myocardial necrosis, supporting a role for contracture in reperfusion-induced cell death.

Actins↗
PubMed1991

Extremely high incidence of antibiotic resistance in clinical isolates of Streptococcus pneumoniae in Hungary.

An epidemiologic survey of antibiotic resistance among pneumococcal isolates collected during 1988 and 1989 in Hungary indicated that as many as 58% of all isolates and 70% of isolates from children were resistant to penicillin. These figures surpass even the highest values reported thus far for Spain and South Africa for the same period. Almost or more than 70% of the penicillin-resistant isolates were also resistant to tetracycline, erythromycin, and cotrimoxazole and approximately 30% to chloramphenicol. Intravenous administration of ampicillin (30 mg/kg) did not interfere with the growth in the cerebrospinal fluid of three resistant strains introduced into the rabbit model of experimental meningitis. No resistant strain showed beta-lactamase activity. A representative highly resistant strain contained altered penicillin-binding proteins (low penicillin affinities and abnormal molecular sizes) and was also resistant to the lytic and killing effects of penicillin.

Adult↗
PubMed1990

Results of EDAP lithotriptor treatment of kidney stones in our first fifty patients.

We report the results of the treatment of the first 50 patients with the EDAP lithotriptor at our center. The EDAP is a second generation lithotriptor that employs ultrasound imaging and piezo-electric energy stone fragmentation. Seventy-six percent of patients had kidney stones completely eliminated or residual no greater than 3 mL. Fourteen percent of patients had residual fragments which may require second treatment. Five stones showed no improvement, and 2 stones could not be imaged. Only 2 patients required anesthesia. One patient required hospitalization prior to treatment. The rest were treated as outpatients. This preliminary FDA-investigative study limited our protocol to stones of 0.5 cm to 2.5 cm within the kidney or proximal ureter. Since particles passed were so small, "steinstrasse phenomenon" (distal ureteral obstruction by stone fragments) was not encountered and routine stent placement was obviated. There were no major complications.

Female↗
PubMed1990

Determinants of hemorrhagic infarcts. Histologic observations from experiments involving coronary occlusion, coronary reperfusion, and reocclusion.

Quantification of intramyocardial hemorrhage was performed in 69 pigs submitted to various protocols of coronary artery occlusion and reperfusion. The study groups include 1) permanent occlusion; 2) reperfusion after periods of coronary occlusion of 30, 45, 60, 90, and 120 minutes; 3) reperfusion with diltiazem and with 4) methoxamine after a 60-minute occlusion period; and 5) permanent reocclusion after a 30-minute period of reperfusion. Red blood cell counts were directly assessed by visual examination of histologic slices of myocardium and in a subgroup of animals by counts of red blood cells labeled with 99m-technetium pertechnetate. Hemorrhage occurs in infarcts reperfused after a duration of 45 minutes or more of coronary occlusion and after a period of reperfusion maintained for at least 30 minutes. Red blood cell counts were maximal in the mid portions of transmural sections of the infarcts, with decreasing values toward epicardium and endocardium. Diltiazem decreased total red blood cell counts, whereas methoxamine increased it and also caused subendocardial hemorrhage. The most powerful predictors of the severity of hemorrhage after sustained reperfusion were infarct size and higher blood pressure.

Animals↗
PubMed1989

A 20-gauge intraocular electromagnetic tip for simplified intraocular foreign-body extraction.

A modified tip for the Bronson intraocular electromagnet has been developed. The tip was machined to a 20-gauge cylinder that can be inserted readily into the eye either through an entrance wound or through a pars plana incision. Placement of the tip of the magnet inside the eye allows the foreign body to impact the tip of the magnet rather than the wall of the eye.

Electromagnetic Phenomena↗
PubMed1989

Relationship between the frequency of piezoelectric shock waves and the quality of renal stone fragmentation. In vitro study and clinical implications.

Nine renal stones were separated into 5 fragments of similar weight and size. One fragment was analyzed chemically and the other 4 fragments were submitted to treatment by piezoelectric shock waves according to the following modalities: 3,000 shock waves at firing frequencies of 1.25, 2.5, 5 and 10 shock waves/s. In the case of hard stones, better quality fragmentation was obtained with low frequencies than with high frequencies. With friable stones, using only 800 shock waves, the result was the same regardless of the frequency used. Treatment of hard stones by shock waves for 20 min at various frequencies revealed that a slightly better result was obtained with a frequency of 5 shock waves/s, although the result was not significantly better. In conclusion, slow frequencies of 1.25 or 2.5 shock waves/s allow better fragmentation of hard stones at the cost of a longer mean treatment than at high frequencies. High frequencies do not give significantly better results than low frequencies when the same firing time is used. In the clinical situation, it is therefore preferable to use low frequencies which allow treatment without anesthesia or analgesia and without admission to hospital.

Humans↗
PubMed1988

Piezoelectric extracorporeal lithotripsy by ultrashort waves with the EDAP LT 01 device.

A total of 433 extracorporeal lithotripsy procedures was performed for renal, ureteral and bladder stones by means of a system of ultrasonographic detection and piezoelectric destruction in 386 patients. The stones were detected easily in 87 per cent of the patients, difficult to detect in 10 per cent and impossible to detect in 3 per cent. Mean duration of treatment was 35 minutes. Mean number of piezoelectric waves was 2,700 at 1.25 per second. With a frequency of 1.25 to 5 per second, extracorporeal lithotripsy was performed without any local, regional or general anesthesia, and without premedication in 210 patients. Of the 217 patients with a renal stone reviewed at 3 months 161 (74 per cent) had successful results and 56 (26 per cent) failed therapy. Thirty patients (14 per cent) underwent 2 or 3 sessions. The morbidity was low: 2 per cent of the patients suffered ureteral obstruction, 1.5 per cent had subcapsular hematoma and 4 per cent had fever. No significant modifications of laboratory tests were necessary and no patient suffered renal failure. Of the stones 31 in the lumbar ureter, 15 in the pelvic ureter and 8 in the bladder were treated, with success rates of 87, 46 and 50 per cent, respectively. A total of 103 patients was treated on an outpatient basis. This outpatient treatment, together with the low cost and minimal maintenance of the apparatus, and the absence of anesthesia constitute a new progress in the treatment of renal stones.

Equipment Design↗
PubMed1987

[Extracorporeal piezoelectric lithotripsy by ultra-short waves using the EDAP LT01 device].

Three hundred and sixty one extracorporeal lithotripsies for renal, ureteric and bladder stones have been performed by means of a system of ultrasonographic detection and piezoelectric destruction (EDAP LT01). The localisation of the stone is achieved by a 5 MHz real time sectorial transducer situated in the centre of a small dish containing 320 piezoelectric elements concentrated in a source 5 mm wide by 15 mm high. The pressure recorded in vitro is 900 bars. The stone is easily detected in 87.2% of cases, difficult to detect in 10% of cases and impossible to detect in 28% of cases. By using a frequency of 1.25 to 5 per second, extracorporeal lithotripsy can be performed without any local, regional or general anaesthesia and without premedication in the 120 patients with a renal stone, reviewed between 1 and 3 months, 88 (73%) were considered to be complete successes. Ten (8%) were considered to be failures and 19 (21%) were considered to be partial successes. The best results were obtained in stones of the renal pelvis less than 20 mm in diameter. These results relate to a mean series which must take into account the successive improvements made to the lithotripter. Today, stone fragmentation is obtained in 93% of cases. Thirty six stones of the lumber and pelvic ureter were treated with success rates of 93% and 50%, respectively. Six bladder calculi were treated with a 50% success rate. Forty two patients were treated without being admitted to hospital.(ABSTRACT TRUNCATED AT 250 WORDS)

Diathermy↗
PubMed1987

[Piezo-electric lithotripsy technic with echographic guidance (EDAP LT 01)].

Piezo-electric extracorporeal lithotripsy with ultrasonographic detection is performed with the following material according to the following technique: 1) A mobile firing head connected to the lumbar region by a simple inflatable cushion filled with sterile water. At the centre of the firing head, a 5 MHz real time transducer is used to locate the stone. 320 piezo-electric elements, arranged around the transducer, can induce, when focussed, a pressure of about 900 bars at the focal point in vitro. The focus is 15 mm X 5 mm. The generators are electronic. 2) The technique requires: understanding of ultrasonography in order to precisely locate the stone which, when it is intrarenal, is only missed in 1% of cases in our experience. Stones of the iliac ureter are not visible. Treatment requires the patient's confidence so that, due to the quality of the piezo-electric wave, no anaesthesia is necessary. The firing time should be relatively long (45 min to 1 hr) in order to ensure good fragmentation. 26% of patients require retreatment. Secondary complications are rare (3% of endoscopic treatments). The technique is now proposed in 90% of cases without admission to hospital. The simplicity of the manipulation of the apparatus must not mask the fact that it is a technique which requires perfect mastery. Only urologists familiar with stone pathology and who are able to treat the complications of lithotripsy by endoscopy or by surgery should perform extracorporeal lithotripsy.

Humans↗