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Biomedical subjects

L Montanari

Publications and source records attributed to L Montanari.

At least 55 records · Page 3Linked to original sources
PubMed1991

Consistent changes in the circadian rhythms of blood pressure and atrial natriuretic peptide in congestive heart failure.

We demonstrated in previous works that the circadian rhythms of blood pressure (BP) and atrial natriuretic peptide (ANP) are antiphasic in normal subjects and in essential hypertension. The aim of the present study was to assess the circadian rhythms of BP and ANP in 20 patients with stable congestive heart failure (CHF), divided into two groups of 10 according to their New York Heart Association functional class. A matched control group of 10 normal volunteers was also studied. Noninvasive BP monitoring at 15-min intervals was performed for 24 h. Peripheral blood samples were also obtained at 4-h intervals starting from 08:00 h. The mean (+/- SEM) circadian mesors of ANP plasma levels were 13.4 +/- 1.7 pmol/L in the control group, 28.6 +/- 2.4 pmol/L in the group of 10 patients in class II, and 81.5 +/- 12 pmol/L in the group of 10 patients in class III-IV. In normal subjects, plasma ANP concentration was highest at 04:00 h (21.5 +/- 2.7 pmol/L) and lowest at 16:00 h (8.8 +/- 2.4 pmol/L; p less than 0.01). Both groups of patients with CHF showed no significant circadian change in the plasma levels of ANP and also a significantly blunted circadian rhythm of BP. Cosinor analysis confirmed the loss of the circadian rhythms of ANP and BP in CHF patients. Our findings support the existence of a causal relationship between the circadian rhythms of ANP and BP.

Adult↗
PubMed1991

Evaluation of factors influencing ampoule secondary particulate contamination. A strategy for its reduction in small volume parenterals.

In this paper, we evaluated the influence of some glass ampoules characteristics that are critical as far as secondary particle contamination (visible and sub-visible) of small volume parenterals. Following characteristics were considered: snap-opening system (colour-break scoring and o.p.c.); break-point strength (high and low); dimensional characteristics (three types D1, D2, D3). According to the proper statistical design, 18 different batches of 2 ml ampoules filled with water for injection were manufactured; then sub-visible and visible particulate contamination generated on snap-opening the ampoules were examined. Sub visible particle counting was performed by the light-blockage method and visible particles counting by the membrane-filtration method. With regard to sub-visible particles, statistical analysis showed significant interactions of break-point strength with both ampoule dimensional characteristics and the type of snap-opening system. Break-point strength seems to have the greatest influence on the level of particulate contamination. Differences in ampoule snap-opening systems and dimensional characteristics exert a significant effect on the level of particle contamination only at high break-point strength. With regard to visible particles generated on snapping the ampoules, data are consistent with the findings of sub-visible particulate contamination. Ampoules manufactured according to DIN dimensional characteristics and with an o.p.c. snap-opening system provide the lowest particle burden.

Drug Contamination↗
PubMed1990

Atrial strain is the main determinant of release of atrial natriuretic peptide.

We studied the response of atrial natriuretic peptide to the hemodynamic and renin-aldosterone variations occurring in four patients who developed cardiac tamponade, either occurring in idiopathic fashion in one or secondary to metastatic involvement of the pericardium in three. Right atrial pressure, heart rate and arterial blood pressure were monitored and serial blood samples were taken before and over three hours after pericardiocentesis. During cardiac tamponade, normal levels of atrial natriuretic peptide (mean +/- SEM: 54 +/- 7.4 pg/ml) were observed in the plasma despite increased right atrial pressure (23 +/- 3.8 cm H2O) and heart rates (98 +/- 4.4). Removal of pericardial fluid (540 to 1160 ml) was associated at first with a 200% increase in plasma concentrations of atrial natriuretic peptide (108 +/- 8.8 pg/ml; P less than 0.001), then with a gradual decline toward normal levels, simultaneous with the normalization of right atrial pressure and heart rate. Activity of renin and concentrations of aldosterone in the plasma were increased during tamponade and returned gradually to normal after pericardiocentesis (3.8 +/- 0.9 to 1.2 +/- 0.3 ng/ml/h and 20 +/- 4.2 to 9 +/- 3.2 ng/dl, respectively; P less than 0.01). These data confirm that atrial strain, not intracavitary pressure in itself nor heart rate, is the main determinant of the acute release of atrial natriuretic peptide, which is associated with a suppressing effect on the renin-aldosterone system. In addition, our data indicate that secretion of atrial natriuretic peptide during cardiac tamponade is not stimulated by secondary hyperaldosteronism.

Adult↗
PubMed1990

Circadian rhythms of atrial natriuretic peptide, renin, aldosterone, cortisol, blood pressure and heart rate in normal and hypertensive subjects.

The occurrence and extent of a circadian rhythm in the circulating concentrations of atrial natriuretic peptide (ANP) are still matters of controversy. Only a few data are available in humans relating the time structure of plasma ANP levels with the circadian patterns of other hormones and cardiovascular variables. In a group of hospitalized normal volunteers (six men and four women, 16-76 years old), and in a group of hospitalized hypertensives (seven men and three women, 18-76 years old), we investigated the circadian variability of ANP and its temporal relationship with the circadian rhythms of blood pressure (BP) and heart rate (HR), and plasma renin activity (PRA), plasma aldosterone (PA) and plasma cortisol (PC) levels, by using a chronobiological inferential statistic method. At the end of a synchronizing period of 1 week (the diet and daily schedule were standardized), the subjects underwent automatic BP and HR monitoring, and blood sampling for 24 h. A statistically significant mean circadian rhythm was demonstrated for ANP, BP, HR, PRA, PA and PC in both normal and hypertensive subjects. The mean circadian acrophase of ANP (calculated to occur at around 04.00 h) anticipated the corresponding acrophases of the other hormones; BP and HR rhythms appeared to be in antiphase with ANP rhythm, i.e. the peak of BP and HR rhythms more or less coincided with the trough in ANP rhythm. A significant increase in the daily levels (assessed by the circadian mesor) of ANP was present in hypertensive subjects when compared with normal controls. In essential hypertension the circadian rhythm of ANP was set at higher circulating levels, but otherwise it was similar to the circadian rhythm found in normals. ANP mesors correlated significantly with renin and aldosterone mesors in normal subjects but not in hypertensive patients. ANP appears to anticipate awakening in its circadian periodic rise. On the basis of the considerable acrophase asynchronism, it seems possible to exclude any causal relations between the periodic changes of ANP and the rhythmic fluctuations of the other hormones that we studied. In contrast, important relations may be hypothesized between ANP levels and BP and HR values, on the basis of their antiphase rhythms.

Aldosterone↗
PubMed1990

Are we overtreating hypertensive patients? Chronobiologic vs. sphygmomanometric evaluation of ambulatory antihypertensive therapy.

The purpose of this prospective study was to compare two methods of evaluating antihypertensive treatment efficacy: the traditional sphygmomanometric method and automatic home recording. Thirty hypertensive patients were studied who had been on antihypertensive therapy for at least 3 months. In the first 3 weeks of study their therapy was left unchanged and their diastolic blood pressures, measured with the traditional sphygmomanometer (weekly morning visit in the outpatient clinic; three successive recordings at 5-min intervals; subject seated), were always higher than 95 mmHg. During the following 8 weeks, the physician tried to reduce diastolic blood pressure to not greater than 90 mmHg by changing or increasing the therapy. Before and after any modification in therapy, noninvasive, automatic home, blood pressure monitorings for 24 hours were obtained and analyzed with Halberg's method of single cosinor, but were not made available to the physician until the end of the study. Automatic recordings showed that 18 patients had already had a circadian diastolic mesor less than or equal to 90 mmHg under the original drug regimen. By changing or increasing the therapy, no additional pressure decrease was seen in the home pressure recordings of the whole group of patients, whereas the sphygmomanometric diastolic pressures of 15 patients fell under 90 mmHg. Our study provides additional evidence that casual sphygmomanometric measurements can be misleading when one tries to assess the efficacy of antihypertensive therapy, and a cause of potential overtreatment.

Adrenergic beta-Antagonists↗
PubMed1990

Altered circadian rhythms of blood pressure and heart rate in non-hemodialysis chronic renal failure.

The extended use of ambulatory monitoring has permitted the identification of many conditions in which the circadian rhythm of blood pressure is altered. The common denominator seems to be an impairment of the autonomic nervous system function. We examined whether the circadian blood pressure rhythm is altered in chronic renal failure (where autonomic dysfunction is usually present) by using a standardized chronobiological inferential statistical method in hospitalized subjects. For this purpose, a group of 30 non-hemodialysis hypertensive patients with chronic renal failure was compared with a second group of 30 patients affected by uncomplicated mild-to-moderate essential hypertension. The two groups were matched by age, sex and circadian mesors of blood pressure. Diet, meal times, sleep, and activity logs were standardized. Blood pressure and heart rate recordings were obtained by using an automatic oscillometric recorder and subsequently analyzed according to the cosinor method. A mean circadian rhythm of blood pressure was documented in both groups, but while the mean acrophases occurred between 2 and 3 p.m. in essential hypertension, in renal failure they were between 11 p.m. and midnight for blood pressure and around 7 p.m. for heart rate. In addition, the mean circadian amplitudes were significantly lower in renal failure, while the mean circadian mesor of heart rate was significantly higher. Our data demonstrate that the circadian rhythms of blood pressure and heart rate are altered also in hypertension due to chronic renal failure.

Adult↗
PubMed1989

Chronobiologic vs. sphygmomanometric assessment of hypertension in a hospital setting.

The aim of this study was to assess the possible correlations between casual measurements and automatic monitoring analyzed with the chronobiologic technique in hospitalized hypertensive patients. Forty-three patients (24 men and 19 women) with mild to moderate essential hypertension were studied in an open hospital ward 5 to 7 days after admission. Meal times, sleep times, and visiting hours were standardized. A clinical value of blood pressure was calculated as the arithmetic mean of three sphygmomanometric measurements taken in the morning (patient seated; 5-min interval between measurements). Then, a basal value of blood pressure was considered as the lowest systolic and the lowest diastolic blood pressure among six sphygmomanometric measurements obtained every 5 min (patient supine). Noninvasive, automatic recording of blood pressure was also obtained every 15 min for 24 hours by a quasiportable oscillometric instrument. Blood pressure recordings were analyzed according to the "cosinor" method of Halberg. On average, clinical blood pressure was 160/96 +/- 14/10 mmHg, significantly higher (p less than 0.005) than either basal blood pressure (150/91 +/- 12/8 mmHg) or 24-h recorded blood pressure mesor (144/88 +/- 13/9 mmHg). The differences were not entirely due to diurnal variations, since morning casual measurements were significantly higher than daytime average blood pressure. A chronobiologic assessment of hypertension in hospitalized patients is more representative of true blood pressure behavior, not only because of the multiple recordings but also because of the absence of an alarm reaction that may trigger a pressor response.

Adult↗
PubMed1989

Circadian rhythms of atrial natriuretic peptide, blood pressure and heart rate in normal subjects.

The occurrence and extent of a circadian rhythm in the circulating concentrations of atrial natriuretic peptide (ANP) is still a matter of controversy. In a group of hospitalized normal volunteers (6 men and 4 women, 16-76 years old), we investigated the circadian variability of ANP and its temporal relation with the circadian rhythms of blood pressure (BP) and heart rate (HR), by using a chronobiological inferential statistical method. At the end of a synchronizing period of 1 week (the diet and the daily schedule were standardized), the subjects underwent automatic BP and HR monitoring, and blood sampling for 24 h. A statistically significant mean circadian rhythm was demonstrated for ANP, BP, and HR. The mean circadian acrophase of ANP was calculated to occur around 4 a.m. BP and HR rhythms appeared to be in antiphase with ANP rhythm, i.e. the peak of BP and HR rhythms more or less coincided with a trough in ANP rhythm. ANP appears to be anticipatory in its circadian periodic rise to awakening. Therefore, postural changes cannot fully account for the diurnal variations observed.

Adolescent↗
PubMed1989

Particulate matter test in small volume parenterals: critical aspects in sampling methodology.

The following critical steps of the particulate matter test sampling methodology for small volume parenteral products (SVPs), conduct by light blockage method, were considered: 1) reliability of the small volume aspirator sampler for different sample volumes; 2) particulate matter distribution inside each ampoule in liquid products (8 liquid SVPs tested); 3) influence of the sample preparation method on the evaluation of the final contamination of the sample. Nine liquid SVPs were tested by preparing samples following the three U.S.P. XXI methods: 1) unit as it is (direct analysis), II) unit diluted, III) sample obtained by combining several units. Particles counts were performed by a HIAC/ROYCO model 3000 counter fitted with a small volume sampler. The validation of the sampler shows that it should be improved. A more accurate and strict validation than the one stated by U.S.P. XXI is suggested. The particulate matter distribution in liquid products is found to be uniform inside the ampoule in the size range greater than or equal to 2 microns-greater than or equal to 10 microns; the analysis can be performed examining only a portion of the whole content. The three sample preparation methods lead to significantly different contamination results. The particulate control test should be conduct by direct analysis, as it is carried out under the same conditions as for product use. The combining method (III) is suggested for products of less than 2 ml volume that cannot be examined by direct analysis.

Drug Contamination↗
PubMed1988

Does placebo lower blood pressure in hypertensive patients? A noninvasive chronobiological study.

Placebo controlled trials have generally been used in order to evaluate the antihypertensive efficacy of drugs. There is some evidence, though, that blood pressure might not be influenced by placebo. Non-invasive devices for automatic blood pressure monitoring are likely to provide a better assessment of blood pressure response to drugs, as well as to different physiologic and pathologic conditions, than the traditional sphygmomanometric devices. The aim of this study was to investigate the effect of placebo on blood pressure recorded automatically and non-invasively. For this purpose, a chronobiologic approach to the collection, evaluation and interpretation of data seemed most appropriate. A group of 12 patients with a clinical diagnosis of essential hypertension underwent automatic blood pressure monitoring in hospital for 4 days. Measurements were taken every 15 min by an oscillometric instrument with an automatically inflated cuff. After a washout period during which the patients received no treatment, pressure recording was undertaken under basal conditions for 2 days. On the third and fourth days of study, the patients received 2 tablets of placebo, one at 10 a.m. and one at 10 p.m. In each patient a highly significant circadian rhythm was documented for systolic and diastolic pressure, both under basal conditions and during placebo administration. Blood pressure mesors were higher than reference standards and were not significantly affected by placebo. The circadian amplitudes and acrophases did not differ significantly before and during placebo. Our data indicate that automatically recorded blood pressure is not influenced by placebo.

Adult↗
PubMed1988

Consistency of circadian blood pressure pattern assessed by non-invasive monitoring and cosinor analysis in hospitalized hypertensive patients.

Non invasive blood pressure monitoring using an automatic Nippon Colin recorder was performed in 20 hospitalized hypertensive patients every 15 min during a 4-day study period. A chronobiologic analysis of the data was performed in order to test the consistency of the whole-day blood pressure pattern. Halberg's method of single cosinor was used to determine the values and the confidence limits of the following parameters of 24-hour rhythmic changes: mesor (rhythm-adjusted 24-hour average), amplitude (24-hour variability estimate), acrophase (clock hour of maximum BP level). The variation of the above parameters during the four 24-hour periods was found to be within 9 mmHg for the systolic mesor, 6 mmHg for the diastolic mesor, 5 mmHg for the systolic amplitude, 4 mmHg for the diastolic amplitude, 55 min for the systolic acrophase, 60 min for the diastolic acrophase. The same parameters were also calculated in 48-hour, 72-hour and 96-hour long time series, and with different sampling periods (30, 60, 120 min). The length of the monitoring span did not influence significantly the values of the rhythm parameters only when 15-min or 30-min sampling periods were used. The widths of the 95% confidence limits of amplitude and acrophase were significantly narrower in the 2-day than in the 1-day series. Further lengthening of the monitoring span from 2 to 4 days resulted in a much smaller additional narrowing of the confidence limits. Sampling periods longer than 30 min caused a loss of sensitivity in rhythm detection.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1987

Effects of captopril on the physical work capacity of normotensive patients with stable-effort angina pectoris.

Twelve normotensive patients with coronary artery disease and stable effort-induced angina pectoris were selected: the antiischemic effect of captopril was studied. A maximal cycloergometer effort test was obtained before (base) and after administration of placebo or captopril (50 mg p.o.). The following parameters were measured: heart rate (HR), blood pressure (BP), maximal rate/pressure product (MRPP), maximal workload sustained, (MWS), maximal working time (MWT), and S-T depression at MRPP. The base and placebo were similar. Compared to them captopril augmented the MWT, increased the MWS, reduced S-T depression at MRPP, and decreased the number of patients with effort-induced angina pectoris. The antiischemic effect of captopril seems related both to its effect on HR and BP, and to a local enhancement of coronary blood flow.

Angina Pectoris↗
PubMed1987

Slow-release nifedipine: effect on the circadian rhythm of blood pressure in essential hypertension.

The aim of this study was to investigate the effect of orally administered, slow-release, nifedipine tablets on the circadian rhythm of blood pressure and heart rate, in hospital patients with clinical diagnosis of hypertension validated by a chronobiologic inferential statistic method. A group of 14 patients (nine women and five men, 47 to 71 years old) with clinical diagnosis of "essential hypertension" underwent automatic blood pressure and heart rate monitoring in a hospital room for 48 hours. Measurements were taken every 15 min by an oscillometric instrument with automatically inflated cuff. The patients received no treatment during the two proceeding weeks and the first day of the study. On the second day, slow-release nifedipine tablets were administered, one at 10 a.m. and one at 10 p.m. A highly significant circadian rhythm was documented for systolic and diastolic blood pressure, mean arterial pressure and heart rate, both in basal conditions and after nifedipine. Blood pressure mesors were higher than reference standards in basal conditions, and were lowered (average decrease = 20 mmHg for systolic and 9 mmHg for diastolic mesor) by nifedipine. A significant, though minor, elevation of heart rate mesor (from 70 to 75 b.p.m.) was also noted during treatment. The circadian amplitudes of blood pressure and heart rate did not differ significantly before and during treatment. In conclusion, the circadian rhythm of blood pressure is still present with the same amplitude after slow-release nifedipine, but is set at a lower pressure level. Heart rate rhythm is also preserved, with only a minor elevation of its mesor.

Administration, Oral↗
PubMed1986

Evaluation of official instrumental methods for the determination of particulate matter contamination in large volume parenteral solutions.

The distribution pattern of particle contamination in nine different types of LV parenteral solutions and the possibility of correlating the counts made with two official instruments (Coulter Counter and HIAC) were studied. Two hundred containers of LV parenteral solutions (corresponding to 40 batches) produced in Italy, were sampled. Each bottle was submitted to HIAC and Coulter Counter countings, for particle sizes ranging between 2 and 25 micron. For about 50% of the products, the two straight lines that represent the distribution of particle contamination obtained with the two methods did not cross-over within the studied size range, the Coulter Counter counts always proving higher than the HIAC ones. In the other cases, the cross-over point of the two lines occurred at varying size levels. Statistical analysis of the results pointed to a relationship between the contamination values obtained with the two counting methods for sizes ranging between 2 and 5 micron, but there was no correlation for sizes equal to, or higher than, 10 micron. From the maximum contamination levels established by the BP and the FU IX for the HIAC method, the corresponding values were calculated for the Coulter Counter method. Similarly the values were calculated the HIAC method based on the maximum values set for the Coulter Counter.

Drug Contamination↗