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Biomedical subjects

S Brenna

Publications and source records attributed to S Brenna.

18 recordsLinked to original sources
PubMed2001

Low nitric oxide values associated with low levels of zinc and high levels of cardiac necrosis markers detected in the plasma of rabbits treated with L-NAME.

Nitric oxide plays a key role as a vasodilating agent and its deficiency is associated with ischemic heart diseases. The aim of this study was to induce biochemical alterations associated with ischemic heart lesions by blocking nitric oxide synthase. L-NAME, a nitric oxide synthase inhibitor, was administered to rabbits and its effects on blood pressure, plasma levels of nitric oxide, zinc and cardiac necrosis markers, heart histology, and electrocardiographic profile were examined. L-NAME administration reduced the nitric oxide levels and consequently increased the diastolic blood pressure. It also caused small areas of myocardial coagulative necrosis, whose dispersed nature made it undetectable by electrocardiograph, and decreased the plasma levels of zinc, which is involved in the enzymatic activities that remove the peroxides damaging the myocardium. This model is proposed for the development of drugs affecting nitric oxide levels with the aim of controlling coronary ischemia.

Animals↗
PubMed2000

Myocardial necrosis in ICU patients with acute non-cardiac disease: a prospective study.

OBJECTIVE: To ascertain if, after an episode of hypotension, unnoticed myocardial necrosis could occur in critical care patients with acute non-cardiac illness and to search for signs of cardiac necrosis. DESIGN: A prospective observational study. SETTING: General intensive care unit (ICU) at a tertiary level hospital. PATIENTS: Thirty-one patients in two groups. Group 1 included 19 patients with severe sepsis/septic shock (ACCP/SCCM Consensus Conference). Group 2 included 12 patients with hypovolemic shock. INTERVENTIONS: Biochemical markers of myocardial necrosis (cardiac troponin I (cTnI), creatine kinase (CK), creatine kinase MB mass (CKMB) and myoglobin) were measured at 12 h (T1), 24 h (T2) and 48 h (T3) after enrollment. A standard 12-lead ECG was recorded upon enrollment (T0) and at T2. Anomalous Q-waves or ST segment depression or elevation was considered diagnostic for acute myocardial infarction (AMI). A hypotensive episode (arterial systolic pressure < 90 mmHg at heart rate > 100 bpm) was considered moderate if it lasted 30-60 min or severe if longer than 60 min. MEASUREMENTS AND RESULTS: At T0 none of the patients had AMI on ECG. At T2 a non-Q AMI developed in five patients. Increased levels of troponin I, myoglobin, CK and CKMB were found in 74.2 %, 96.8 %, 74.2 % and 67.7 % of the patients, respectively. Cardiac troponin I increased in 11 out of 19 septic patients and in all hypovolemic patients. There was a significant difference between the groups (p < 0.05). All biochemical markers increased in relationship to the degree of hypotension with cTnI again showing a significant difference. The longer the hypotensive episode was, the greater was the increase (moderate hypotension: median 1.16; quartiles 0.55-3.44 ng/ml, severe hypotension: median 8.53; quartiles 1.1-20.7 ng/ml; p < 0.05). Abnormal levels of cTnI were more frequent in non-survivors than in survivors (p < 0.05). CONCLUSIONS: Hypotension may cause cardiac damage in critically ill patients with acute non-cardiac diseases as shown by abnormal levels of cTnI. It is likely that a high number of these myocardial necroses may go unnoticed on the ECG.

Aged↗
PubMed1998

Pitfalls in measuring inulin and para-amino-hippuric acid clearances.

Various carbohydrates and a variety of widely used medicines interfere with the generally used laboratory methods for determining inulin and para-aminohippuric acid (PAH). When these pitfalls are not recognized, false measurements of inulin and PAH clearances, which represent glomerular filtration rate and renal plasma flow respectively, are obtained. When performing these tests a careful history of dietary habits and oral drug therapy must be taken.

Ammonium Chloride↗
PubMed1998

Effect of magnesium sulfate on kidney function in the newborn rabbit.

The aim of this study was to investigate the acute, short-term effects of the intravenous (i.v.) administration of magnesium (Mg) sulfate on renal function in the newborn rabbit. Eight anesthetized and mechanically ventilated, normoxemic, newborn New Zealand white rabbits were studied. We measured mean arterial blood pressure (MAP), urine volume (V), glomerular filtration rate (GFR), renal plasma flow (RPF) and calculated renal blood flow, filtration fraction (FF) and renal vascular resistance (RVR) under control conditions and in two experimental periods after the i.v. Mg sulfate load. Mg sulfate administration in a dose 100 mg/kg followed by 50 mg/kg/h caused a significant fall (p < 0.001) in MAP, GFR and RPF, whereas the RVR increased (p < 0.01). FF did not change significantly (p: NS/0.05) and V remained constant. These results show that the acute i.v. administration of Mg sulfate to newborn rabbits causes systemic vasodilatation with a fall in MAP. The increase in RVR, without consistent change in FF, suggests that the renal vasculature of the 'immature' neonatal rabbit reacts to these changes by preferential afferent arteriolar vasoconstriction.

Animals↗
PubMed1995

Identification of cells secreting a thymostimulin-like substance and examination of some histoenzymatic pathways in aging avian primary lymphatic organs: I. thymus.

Thymi of adult chickens (White Leghorn strain), ages of 6, 18, 45, days and 1, 3, 6, months, were studied by histological and histochemical stainings, histoenzymatic reactions (LDH, SDH, alpha-GPDH, NADH, NADPH, Ca++ dependent ATPase, pH 8.5) and by anti-thymostimulin immunoreaction. Positive reactions for thymostimulin-like substance, mucopolysaccharides and enzymatic activities were located in different epithelial compartments of the cortical and medullary zones. In 3 and 6 month-old chickens, there was a progressive reduction of the cortical area and of the number of cortical and medullary epithelial cells, and, in the thymi of the 6 month-old chickens, a partial decline in the immunological reactivity to anti-TS, but the intensity of the histochemical and enzymatic reactivities, in comparison with the thymi of the youngest chickens, was not decreased. This may suggest that the cortical and medullary epithelial cells still present in these thymi are capable of secreting and expressing activities and, thus, may maintain their functions.

Adjuvants, Immunologic↗
PubMed1992

Axon clinical chemistry analyzer evaluated according to ECCLS protocol.

We assessed the analytical performance of the Axon system (Bayer Diagnostici), according to the European Committee for Clinical Laboratory Standards guidelines, for assay of 12 analytes: cholesterol, creatinine, glucose, total protein, urea, uric acid, alkaline phosphatase, alpha-amylase, aspartate aminotransferase, creatine kinase, sodium, and potassium. The field evaluation lasted approximately 5 months and involved the collection of approximately 10,000 data points with the Axon. The following results were obtained: The highest CVs for controls and human sera at different concentration/activity values were 2.2% for within-run imprecision (n = 60; 3 days, pooled estimate) and 3.5% for the between-day imprecision (n = 20 days). Close correlation was found with results for patients' specimens assayed with comparative instruments (Hitachi 717 for substrates and enzymes, Beckman Synchron EL/E4A for electrolytes). No drift was observed during 8 h of operation. The linearity range was broad, sometimes exceeding the manufacturer's claims. No sample-, reagent-, or cuvette-related carryover was found. Measurement of control sera gave results within +/- 5% of the assigned values. We conclude that good reliability and practicability make the Axon system suitable for laboratories with various needs.

Blood Chemical Analysis↗
PubMed1992

[Results of multicenter evaluation of reagents for determination of sodium, potassium and chloride ions using enzyme activation].

We present the results of a multicentre evaluation with Boehringer Mannheim/Hitachi instruments of new "enzymatic" methods for the determination of Na+, K+, and Cl- in serum or plasma. The between-day coefficient of variation was less than 1.4% (Na+), less than 2.6% (K+) and less than 1.7% (Cl-). The linear range of the assays were at least 80 to 200 mmol/l (Na+), 1.5 to 17 mmol/l (K+) and about 30 to at least 200 mmol/l (Cl-). The comparisons with routine flame atomic emission spectrometry and coulometry showed a satisfactory agreement of the test results. The "enzymatic" assays are insensitive to even grossly elevated levels of bilirubin and lipids (sodium, potassium, and chloride assays), NH4+ (potassium assay) and amylase (chloride assay). Interference by various drugs was not detected. Since the new methods can easily be adapted to photometric clinical chemistry instruments, they represent a valuable alternative to the use of ion-selective electrodes, flame atomic emission spectrometry and coulometry.

Calibration↗
PubMed1990

Multicentre evaluation of the Boehringer Mannheim/Hitachi 717 analysis system.

We conducted an European multicentre trial to assess the performance of the new Boehringer Mannheim/Hitachi 717 analysis system. The photometer response was linear up to an absorbance of 2.8. The maximal CV of photometric imprecision was 0.5% for the wavelength pair 340/405 nm within the absorbance range 0.9 to 2.4. For the 13 analytes in our study, mean within-run imprecision was less than 2%, and mean between-day imprecision less than 2.5%. The results obtained with the Hitachi 717 instrument correlated closely with those of comparison instruments. Linearity for the various tests was high and exceeded the manufacturer's claims. No drift was detected during an 8-hour work period; carry over could not be detected under the chosen experimental conditions. The new instrument was readily accepted by the evaluators because of its ease of handling and simple daily maintenance.

Blood Chemical Analysis↗
PubMed1987

A multicentre evaluation of the Boehringer Mannheim/Hitachi 704 analysis system.

The selective multitest Boehringer Mannheim/Hitachi 704 analysis system was examined according to the ECCLS guidelines in a multicentre evaluation involving four laboratories. Ten routine parameters, covering most of the application settings of the instrument, were measured in the respective laboratory at temperatures 25, 30 or 37 degrees C. The trial lasted four months and gave more than 40,000 data. It yielded the following results: 1. Within the four laboratories the mean coefficients of variation for three control sera at different concentrations were found to be equal to or better than 1.6% for the within-run imprecision and 2.8% or better for the between-day imprecision. 2. No drift was observed during eight hours. 3. Because of the high linear measuring range a re-run analysis was seldom necessary. 4. Sample-related carry-over was not seen. Reagent-dependent carry-over was measured from cholesterol to uric acid and from triacylglycerols to lipase. Through modification of the cholesterol and triacylglycerol reagents, the carry-over effect was practically eliminated. 5. The recovery of the assigned values of control sera showed average values between 99 and 104%. For bilirubin, creatinine, creatine kinase and alanine aminotransferase some control sera showed deviations greater than 10%. 6. In all cases, regression analysis of the results obtained in comparisons of the present instrument with the Hitachi 705 or 737 yielded slopes close to unity with extreme values of 0.95 and 1.06. 7. During the entire evaluation period there was no malfunction or breakdown of the instruments. The evaluators came to the conclusion that the analytical performance as well as the reliability and practicability of the Hitachi 704 can be rated as excellent.

Autoanalysis↗
PubMed1987

Assessment of an automatic liquid chromatograph for foetal and abnormal haemoglobins.

The DIAMAT TM (Bio-Rad) analyser is a microprocessor-operated HPLC system using a silica-based weak cation exchange column with three phosphate buffers of increasing ionic strength as the step gradient mobile phase. A dual wavelength detector measures absorbance at 415 and 690 nm; each sample is completely processed in 8 minutes. The instrument effectively separates and quantifies HbF in a discrete peak. We have verified that the HbF assay is linear up to about 65% values. We calculated within-run imprecision for n = 20 in 3 different haemolysed blood samples; the results are shown below as percent of total haemoglobin: A) Mean = 1.06 SD = 0.048 CV% = 4.5 B) Mean = 1.90 SD = 0.041 CV% = 2.1 C) Mean = 8.93 SD = 0.047 CV% = 0.5 Between-run imprecision for similar samples (n = 18) was: D) Mean = 3.74 SD = 0.20 CV% = 5.5 E) Mean = 9.94 SD = 0.15 CV% = 1.5 Accuracy was assessed in different series by correlating Hb values (y) with those obtained by the alkali denaturation test (x). The regression line equation was y = 1.03 x - 0.33 (r = 0.999, n = 62). The DIAMAT TM instrument also reveals the presence of any HbS and calculates its peak area correctly, as we found by electrophoretic reassay in heterozygous subjects. We also noted the presence of other abnormal haemoglobins characterized by specific retention times.

Autoanalysis↗
PubMedDate not supplied

[Clinical-statistical analysis of patient admissions to the emergency services of the Bambino Gesù Hospital in Rome in the year 1992].

The Authors present relevant information concerning the activity carried on in 1992 in the Emergency Department of the Pediatric Hospital Bambino Gesù in Rome. Out of 34,328 cases arrived at the first aid station, only 21.17% of them needed an emergency service. This significant percentage suggests that the pediatric medical staff in service may be better employed for children who really need urgent care.

Age Factors↗