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Biomedical subjects

F Marchi

Publications and source records attributed to F Marchi.

At least 19 recordsLinked to original sources
PubMed2001

Unstimulated salivary flow rates of young children.

OBJECTIVE: Studies on salivary flow rates in human beings have mainly been carried out with adults. The purpose of this study was to determine the unstimulated salivary flow rates of children 4 to 7 years old. In addition, the relative contributions of the variables age, gender, race, height, body weight, dentition status, use of prescription medication, and health status (information obtained from parents) to the unstimulated salivary flow rates of children were also studied. STUDY DESIGN: Data were obtained from children (n = 447) at 2 sites in the United States (site 1, southeast Michigan; site 2, northern Michigan) and at 5 sites in Brazil (site 3, Porto Alegre; site 4, São Paulo; site 5, Belém; and sites 6 and 7, sites in Rio de Janeiro). In northern Michigan (site 2) the participants were cognitively or developmentally disabled, or both. In Rio de Janeiro (site 7), a group of 8- to 12-year-olds served as a control group. Saliva samples were collected for 3 minutes between 9 AM and noon in the spring or summer, and the saliva rate was determined gravimetrically. Data were analyzed by analysis of variance, bivariate analysis, and regression analysis. RESULTS: The secretion rates at the 7 sites were (in milliliters per minute) 0.19 +/- 0.15, 0.23 +/- 0.28, 0.34 +/- 0.23, 0.48 +/- 0.37, 0.25 +/- 0.27, 0.37 +/- 0.28, and 0.61 +/- 0.34, respectively. There were significant differences among sites (P <.0001). The older group (site 7) had flow rates that were significantly higher than the flow rates of any other group. In addition, children from Michigan (sites 1 and 2) had significantly lower rates than most groups of children in Brazil. Girls had lower unstimulated salivary flow rates than boys did at all the sites, but the differences were not statistically significant. Race was shown not to affect the flow rates. The use of any prescription medication by children in the previous 3 months was associated with lower salivary flow rates than were found in children not using prescription medication. Children who were in good health and who had no previous medical conditions had higher flow rates--but not significantly so. Higher flow rates occurred in children with mixed dentition than in children with primary dentition, although again the differences were not statistically significant. Regression analysis revealed weight to be of significance in explaining the variability of the unstimulated salivary flow rates at 2 sites, height at 1 site, the use of prescription medication at 2 sites, and age at 1 site. CONCLUSIONS: The unstimulated salivary flow rates in children in the northern United States are comparable with those reported for Japanese children, whereas the flow rates of children in Brazil are comparable with those reported for North American and European adults. In addition, none of the demographic variables/parameters tested contributed consistently to the variability of the unstimulated salivary flow rates in children at the 7 sites assessed in this study.

Age Factors↗
PubMed1999

Relationship between anteroposterior maxillomandibular morphology and masticatory jaw movement patterns.

The causal relationships between oral function and craniomandibular morphology are poorly understood. The aim of this study was to determine whether quantifiable features of masticatory jaw movements and associated EMG activity correlated with variation in morphology as defined by the ANB angle. Thirty-six healthy subjects with no previous orthodontic treatment, asymptomatic masticatory muscles, and asymptomatic temporomandibular joints participated. While subjects chewed gum, jaw movement data and surface EMG data were digitized and then quantified into a 300 variable vector for each subject. ANB angle measurements were calculated from digitized tracings of lateral cephalographs. Step-wise linear regression and discriminant analyses were used to determine the relationship between the ANB angle and a subset of the variables defining jaw movement patterns and EMG patterns. A linear combination of seven jaw movements and EMG variables accounted for over 75% of the variation in the ANB angle (adjusted x R2 = 0.78, P <.001). A jackknifed cross-validation of the discriminant analysis, which was forced to use the same seven variables as the regression analysis, resulted in correct classification of 14 of 20 skeletal Class I, 7 of 9 skeletal Class II, and 7 of 7 skeletal Class III subjects. These results suggest that there is an association between anteroposterior skeletal morphology, as quantified by the ANB angle, and masticatory jaw movement patterns, as quantified in this study.

Adolescent↗
PubMed1991

Changes in cells's secretory organelles and extracellular matrix during endochondral ossification in the mandibular condyle of the growing rat.

The mandibular condyle from 20-day-old rats was examined in the electron microscope with particular attention to intracellular secretory granules and extracellular matrix. Moreover, type II collagen was localized by an immunoperoxidase method. The condyle has been divided into five layers: (1) the most superficial, articular layer, (2) polymorphic cell layer, (3) flattened cell layer, (4) upper hypertrophic, and (5) lower hypertrophic cell layers. In the articular layer, the cells seldom divide, but in the polymorphic layer and upper part of the flattened cell layer, mitosis gives rise to new cells. In these layers, cells produce two types of secretory granules, usually in distinct stacks of the Golgi apparatus; type a, cylindrical granules, in which 300-nm-long threads are packed in bundles which appear "lucent" after formaldehyde fixation; and type b, spherical granules loaded with short, dotted filaments. The matrix is composed of thick banded "lucent" fibrils in a loose feltwork of short, dotted filaments. The cells arising from mitosis undergo endochondral differentiation, which begins in the lower part of the flattened cell layer and is completed in the upper hypertrophic cell layer; it is followed by gradual cell degeneration in the lower hypertrophic cell layer. The cells produce two main types of secretory granules: type b as above; and type c, ovoid granules containing 300-nm-long threads associated with short, dotted filaments. A possibly different secretory granule, type d, dense and cigar-shaped, is also produced. The matrix is composed of thin banded fibrils in a dense feltwork. In the matrix of the superficial layers, the "lucency" of the fibrils indicated that they were composed of collagen I, whereas the "lucency" of the cylindrical secretory granules suggested that they transported collagen I precursors to the matrix. Moreover, the use of ruthenium red indicated that the feltwork was composed of proteoglycan; the dotted filaments packed in spherical granules were similar to, and presumably the source of, the matrix feltwork. The superficial layers did not contain collagen II and were collectively referred to as perichondrium. In the deep layers, the ovoid secretory granules displayed collagen II antigenicity and were likely to transport precursors of this collagen to the matrix, where it appeared in the thin banded fibrils. That these granules also carried proteoglycan to the matrix was suggested by their content of short dotted filaments. Thus the deep layers contained collagen II and proteoglycan as in cartilage; they were collectively referred to as the hyaline cartilage region.

Actin Cytoskeleton↗
PubMed1991

[Adaptation to effort myocardial ischemia].

BACKGROUND: During PTCA it has been observed that in two sequential coronary occlusions, the second is characterized by less subjective anginal discomfort, less ST segment depression, less myocardial lactate production and lower mean pulmonary pressure than that recorded during the first inflation. The phenomenon is known as "cardiac adaptation to ischemia". PTCA, as a model for controlled, reversible myocardial ischemia must be viewed in a substantially different context from other models concerning different types of ischemia. The purpose of our investigation was to examine the hypothesis that phenomena similar to those observed during PTCA can occur during effort ischemia. METHODS: Six patients with stable effort ischemia, fixed ischemic threshold (bpm x mmHg variability less than 3200) and fixed recovery period (variability of time at ST on isoelectric line less than 1 min and variability of rate-pressure product at ST on isoelectric line less than 2000 bpm x mmHg) were studied. Our aim was to study the ischemic threshold (IT) and the recovery period in an exercise test performed a short time after an initial one. The programme consisted of: 1) exercise test at a fixed load (the load was predetermined by the level of ischemia reached in a previous multistage exercise test); 2) exercise test ending at ST decreases 1 mm; 3) recovery period; 4) 2nd exercise test similar to the first one and ending at ST decreases 1 mm, to be performed 3 minutes after the end of recovery period (that is, 3 minutes after ST on isoelectric line). In both exercise tests we registered rate-pressure product at ischemia (RPPI), time to ischemia (TI), rate-pressure product at ST on isoelectric line (rate-pressure product at normalization: RPPN) and time at ST on isoelectric line (time of normalization: TN). RESULTS: [table: see text] In all pts RPPI in the second exercise test was similar to RPPI registered in the first one, while RPPN in the second exercise test was higher than in the first. In the second exercise test, time to ST on isoelectric line was also shorter. CONCLUSIONS: We think that the shorter recovery period from myocardial ischemia in the second exercise test may be an expression of a "cardiac adaptation to ischemia", a phenomenon which has been previously observed during PTCA.

Adult↗
PubMed1990

[Myocardial ischemia induced by exercise. Analysis of the recovery phase. Behavior of the rate-pressure normalization product in patients with fixed ischemic threshold and patients with variable ischemic threshold].

Traditionally, in patients with exercise-induced myocardial ischemia we analyze the stress-test by studying the behaviour of double product at ischemia. We recognize the presence of a functional component in the reduction of coronary-flow reserve if the double product at ischemia (DPI) varies in 3 stress-tests i.e. more than 20% or more than 3200 mmHg b m'-1. Any analysis that relies exclusively on double product at ischemia is, of necessity, limited to the beginning of the ischemic phenomenon. To better understand the development of the whole event, we also considered the double product calculated when the ischemic electrocardiographic signal regressed (double product of normalization: DPN). More specifically, we set out to determine whether or not double product at ischemia behaviour in patients with variable ischemic threshold (i.e. double product at ischemia variation greater than 3200 mmHg b m'-1) differs from that of patients with fixed ischemic threshold (i.e. double product at ischemia variation less than b m'-1). We performed four multistage bicycle ergometer tests, without drugs, on 19 patients with chronic exertional anginal and exercise-induced ST depression. Patients were tested at the same time of day, within a 10 day period. In the second, third and fourth stress test double product at ischemia was calculated. On the basis of double product at ischemia values in three stress-tests, we distinguished two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Buprenorphine and pentazocine in acute myocardial infarct. Study for a differential use].

Morphine is known as the best analgesic for patients with acute myocardial infarction complicated by heart failure. In patients with uncomplicated acute myocardial infarction, buprenorphine has recently been indicated as an alternative to the widely used pentazocine. In order to verify if the haemodynamic effects of the two drugs differed, a randomized double-blind controlled trial was performed on 20 patients with uncomplicated acute myocardial infarction: 10 patients were treated with i.v. pentazocine 30 mg. and 10 patients with buprenorphine 0.30 mg. (equianalgesic doses). Right atrial, ventricular and pulmonary artery and capillary pressure, cardiac index, total pulmonary and total systemic resistance were measured before testing and 15', 30', 60', 180' and 240' after drug injection. PO2 was measured before drug injection and 30' and 60' later. Data were analyzed using the Wilcoxon test. All patients in each group showed uniform results: pentazocine increased total systemic resistance (mean increase 17%) while buprenorphine lowered it (mean reduction 12%) (P less than 0.05). Pentazocine lowered cardiac index (mean reduction 5.9%) while buprenorphine increased it (mean increase 9.3%) (P less than 0.05). Maximum changes occurred within 60' after the administration of both drugs. The other parameters did not change significantly from basal values. These results suggest that in patients with acute myocardial infarction uncomplicated by heart failure pentazocine and buprenorphine may be used in different haemodynamic situations. In the cases in which a reduction in total systemic resistance is desired, buprenorphine seems most suitable. However, in the presence of vagal reaction for instance, pentazocine may be administered.

Buprenorphine↗
PubMed1988

[Chronobiological study of ischemic attacks in angina pectoris at rest].

The aims of this study were to determine if the hourly distribution of ischaemic episodes differed as regards ST segment elevation or ST segment depression during ischaemic attacks and differed as regards the degree of coronary atherosclerotic involvement. Twenty-four in-patient drug free subjects with angina at rest underwent ECG continuous Holter monitoring for periods varying from 24 to 168 hours. Four groups of patients were identified: group 1A: 6 patients with ST elevation and 0-1 vessel disease; group 1B: 6 patients with ST elevation and 2-3 vessel disease; group 2A: 3 patients with ST depression and 0-1 vessel disease; group 2B: 9 patients with ST depression and 2-3 vessel disease. During Holter monitoring, 301 ischaemic episodes were registered in group 1A during 576 hours; 173 episodes were registered in group 1B during 624 hours; 41 episodes were registered in group 2B during 528 hours. Using the single and population mean cosinor tests on the episodes of each group, considered as a whole, the following results were found: group 1A showed a circadian rhythm with acrophase at 4:03 a.m. (Fig. 2), group 1B showed a circadian rhythm with acrophase at 10:51 a.m. (Fig. 3), group 2A showed a circadian rhythm with acrophase at 11:15 p.m. (Fig. 5), while group 2B showed ultradian rhythms which lasted 7 and 13 hours (Fig. 6). The chronobiologic analysis of the distribution of the ischaemic attacks confirmed the existence of a circadian rhythm of ischaemic episodes in patients with ST elevation.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1987

[Acute antiarrhythmia treatment with amiodarone and blood levels of thyroid hormones].

Amiodarone has a good antiarrhythmic effect administered either acutely or chronically. Since the antiarrhythmic effect of chronically administered amiodarone has been thought to be dependent on a depression of thyroid function, we studied the peripheral hormonal pattern of 10 euthyroid patients with ventricular arrhythmias who had been responsive to the acute intravenous administration of the drug (10 mg/Kg). During the first 12 hours following the drug administration, reverse T3, free T3 and free T4 values and QTc duration were unchanged. Therefore the antiarrhythmic effect of amiodarone when acutely administered has no correlation with thyroid hormone serum changes.

Amiodarone↗
PubMed1984

Radioautographic characterization of successive compartments along the rough endoplasmic reticulum-Golgi pathway of collagen precursors in foot pad fibroblasts of [3H]proline-injected rats.

Young rats given an intravenous injection of [3H]proline were killed at successive times from 4 to 80 min later. Fibroblasts from the front foot pad were radioautographed ; silver grains were counted over several of the organelles and the results were expressed as percent radiolabel per unit volume. These percentages reached a peak over rough endoplasmic reticulum cisternae at 4 min, intermediate vesicles and tubules at 10 min, spherical distensions of cis-side Golgi saccules at 20 min, cylindrical distensions of trans-side saccules between 40 and 60 min, and secretory granules at 60 min. It is proposed that the succession of peaks corresponds to the migration pathway of collagen precursor proteins within fibroblasts; that is, the proteins synthesized in rough endoplasmic reticulum are delivered by intermediate vesicles and/or tubules to the spherical distensions of cis-side saccules, somehow pass from there to the cylindrical distensions of trans-side saccules and, finally, are carried by secretory granules to the extracellular space.

Animals↗
PubMed1983

Collagen biogenesis and assembly into fibrils as shown by ultrastructural and 3H-proline radioautographic studies on the fibroblasts of the rat food pad.

To examine whether collagen is assembled into fibrils within or outside fibroblasts, the connective tissue of the rat foot pad was investigated by electron microscopy and by radioautography at times varying from 4 min to 3 days after an intravenous injection of 3H-proline. The fibroblasts of the rat food pad are long polarized cells with the nucleus at one end, the Golgi apparatus in the center, and a region with long processes at the other end. This region contains secretory granules and is considered to be the secretory pole of the cell. In the Golgi apparatus the stacks of saccules are separated from rough endoplasmic reticulum (rER) by groups of "intermediate vesicles" including similarly structured tubules which may be over 300 nm long and are referred to as "intermediate tubules." The Golgi saccules exhibit distended portions which differ at the various levels of the stack. On the cis side, the distentions tend to be spherical and contain fine looping threads; in the middle of the stack, they are cylindrical and present distinct straight threads; whereas on the trans side, they are again cylindrical, but the straight threads are grouped in parallel aggregates. Between these cylindrical distentions and the secretory granules, there are transitional forms within which thread aggregates are packaged more and more tightly. Finally, the fibroblasts are associated with two types of collagen fibrils: extracellular ones arranged into large groups between the cells and intracellular ones located within long intracytoplasmic channels. Quantitative radioautography after 3H-proline injection reveals that the number of silver grains per unit area reaches a peak over the rER at 4-10 min, Golgi apparatus at 40 min, secretory granules at 60 min, and extracellular collagen fibrils at 3 h. At no time are intracellular collagen fibrils labeled. Qualitative observations further indicate that spherical Golgi distentions are mainly labeled at 40 min, and cylindrical distentions, at 60 min. In addition, from 20 min to 3 hr, some lysosomal elements are labeled. The biogenetic pathway leading to the formation of collagen fibrils is interpreted as follows.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Silent myocardial ischemia during ambulatory electrocardiographic monitoring in patients with effort angina.

The frequency and characteristics of asymptomatic ischemic attacks were investigated in 39 patients with effort angina. During 24 hour Holter monitoring, 32 of the 39 patients displayed one or more episodes of ischemic ST depression. Eight patients had attacks (n = 25) always accompanied by pain; 9 patients had only asymptomatic ischemic episodes (n = 40) and 15 patients had both symptomatic (n = 29) and asymptomatic attacks (n = 76). In the 15 patients exhibiting both symptomatic and asymptomatic attacks, mean duration of symptomatic episodes was longer (probability [p] less than 0.001) and mean maximal ST depression was greater (p less than 0.001). When patients exhibiting only symptomatic episodes were compared with those exhibiting only asymptomatic attacks, differences were not significant. All symptomatic and asymptomatic attacks during Holter monitoring were correlated with the results of stress testing: patients experiencing a delayed response to pain after the onset of St ischemic depression during stress testing had a higher ratio of asymptomatic to symptomatic attacks during Holter monitoring compared with those patients reporting pain before or at the moment of the appearance of ischemic electrocardiographic features during stress testing. It is concluded that: 1) asymptomatic episodes of ischemia are more frequent than symptomatic episodes in patients with effort angina; 2) in the same patient, the severity of ischemia is generally a fundamental factor in determining the presence or absence of pain during an ischemic attack; and 3) differences among patients with respect to predominance of symptomatic or asymptomatic attacks probably depend on individual factors.

Angina Pectoris↗