Biomedical subjects

M A Revilla

Publications and source records attributed to M A Revilla.

8 recordsLinked to original sources

PubMed2006

Gibberellins and antheridiogen on sex in Blechnum spicant L.

The role of gibberellins (GAs) in determining sex in the gametophyte of the fern Blechnum spicant L. was studied through (a) the effect of exogenous GA(4+7) and GA3 (b) quantitation of the endogenous levels of GA1, GA3, GA4, GA7, GA9, and GA20 in male and female gametophytes, and (c) the effect of flurprimidol, a GAs biosynthesis inhibitor of the steps of oxidation of ent-kaureno to ent-kaurenoic acid. Our results show that GA(4+7) had a slight effect of inducing either male or female sexual organs, antheridia and archegonia, respectively. The endogenous GAs content was not significantly different between sexes, but the GA4, GA7, and GA20 levels were raised above those of the other GAs in both sexes. Neither antheridiogen biosynthesis nor antheridia formation was inhibited by flurprimidol. Gametophytes regenerated from homogenized mature gametophytes (HG) show a different physiological behavior than spore-derived gametophytes. In the first case, gametophytes are males and synthesize antheridiogen before they attain maturity, in contrast to what occurs in spore-derived gametophytes which are females and synthesize antheridiogen when mature.

Abscisic Acid↗

PubMed2006

Exogenous and endogenous growth regulators on apogamy in Dryopteris affinis (Lowe) Fraser-Jenkins sp. affinis.

This work showed for the first time the relationship between the effect of exogenous auxins and gibberellins on apogamy in Dryopteris affinis (Lowe) Fraser-Jenkins sp. affinis and its endogenous contents during early apogamic events. The addition of NAA (0.53 and 5.37 microM) or GA(3) 2.8 microM to an MS solid medium significantly increased apogamous sporophyte formation. BA induced brown callus that regenerated sporophytes in a hormone-free medium. The endogenous contents of GA(1), GA(3), GA(4), GA(7), GA(9) and IAA were determined by GC-MS in gametophytes cultured on MS solid medium, before and during early stages of apogamous embryo development. The accumulation of both GA(9) and IAA before embryo development was evident as high levels of GA(4) in the earliest analysed stage of embryo development and high levels of GA(3) in elongating shoots were found. The role of gibberellins on apogamy was also supported by data showing a decrease in the percentage of gametophytes developing embryos because of the addition of flurprimidol to the culture medium.

Dryopteris↗

PubMed1997

Computer analysis of environmental temperature, light and noise in intensive care: chaos or chronome nurseries?

Lighting, noise and temperature were monitored in two perinatal nurseries. Rhythms of several frequencies were found, including prominent 24-hour rhythms with acrophases around 13:00 (light intensity) and 16:00 (noise). For light and noise, the ratio formed by dividing the amplitude of a 1-week (circaseptan) or half-week (circasemiseptan) fitted cosine curve by the amplitude of a 24-hour fitted cosine curve is smaller than unity, since 24-hour rhythms are prominent for these variables. The amplitude ratios are larger than unity for temperature in the newborns' unit but not in the infants' unit. Earlier, the origin of the about-7-day rhythms of neonatal physiologic variables was demonstrated to have, in addition to a major endogenous, also a minor exogenous component. Hence, the possibility of optimizing maturation by manipulating environmental changes can be considered, using, as gauges of development, previously mapped chronomes (time structures of biologic multifrequency rhythms, trends and noise).

Circadian Rhythm↗

PubMed1997

Heart rate biorhythm changes during the first three months of life.

UNLABELLED: Heart rate (HR) was recorded in healthy full-term newborns aged 1-90 days. The aim of this study was to study the existence of circadian and/or ultradian rhythms in HR to determine maturity. HR was recorded during 24 h, at 30-min intervals, at different postnatal ages. Six-groups were investigated: day 1 (group 1); day 7 (group 7); day 15 (group 15); day 30 (group 30); day 60 (group 60), and day 90 (group 90). The chronograms for HR showed peaks and nadirs along the 24-hour periods, and the cosinor analysis proved the existence of 3-hour ultradian rhythm in groups 1, 7 and 30, and a 12-hour ultradian rhythm in group 90 (p < 0.01 in all cases). The same type of analysis confirmed the existence of a circadian rhythm in group 30. Similar results were obtained for groups 60 and 90 (p < 0.05). IN CONCLUSION: at birth, newborns have an endogenous ultradian period of 3 h. A circadian rhythm appears within 15-30 days of postnatal life.

Aging↗

PubMed1996

Resonance of about-weekly human heart rate rhythm with solar activity change.

In several human adults, certain solar activity rhythms may influence an about 7-day rhythm in heart rate. When no about-weekly feature was found in the rate of change in sunspot area, a measure of solar activity, the double amplitude of a circadian heart rate rhythm, approximated by the fit of a 7-day cosine curve, was lower, as was heart rate corresponds to about-weekly features in solar activity and/or relates to a sunspot cycle.

Adult↗

PubMed1995

Development of sleep-wakefulness rhythm in premature babies.

The aims of this study were: (1) to investigate the evolution of the sleep pattern in preterm newborns during their first month of life; (2) to assess the influence of light-dark on the sleep pattern; and (3) to compare this pattern with that of full-term newborns. The population consisted of 60 healthy, preterm newborns and 63 full-term newborns, divided into four age groups, 1 week apart, throughout the first month of life. Preterm newborns were further divided into five groups according to conceptional (corrected) age. An observer took note every 30 min, for 24 h, of sleep or wakefulness in every case. The average sleeping time in preterm groups according to postnatal age remained unchanged during the first month of life: 17.57 h on day 1 and 17.15 h on day 28. When the preterm infants were re-grouped according to conceptional age, average daily sleep was 17.86 h at 32 weeks and 15.22 h at 37 weeks. The full-term newborns had an average daily sleep of 14.78 h on day 1 and 11.94 h on day 28, with a decrease throughout week 4 of life (p < 0.001). The decrease in daily sleeping time in the full-term groups, took place at the expense of the daylight span, where there was a decrease throughout the first month of life (p < 0.01). There were no differences in preterm newborns during the light and dark phases. A progressive synchronization of sleep to the light-dark was seen in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian Rhythm↗

PubMed1986

A new and permanent staining method for starch granules using fluorescence microscopy.

A fluorescence technique has been developed for observing starch granules in plant tissues. Sections are stained with a mixture of dyes which we have named F.A.S.G.A. from the initials of the Spanish names of its components (fucsina, alcian blue, safranina, glicerina, agua), and viewed by epifluorescence microscopy. The starch granules fluoresce greenish yellow, allowing the degradative state to be observed. Cell structures which do not fluoresce are also differentiated. The stain permits identification of other structures when examined by visible light microscopy and is relatively resistant to fading over time.

Fabaceae↗

PubMedDate not supplied

[Chronobiological profile of arterial blood pressure and heart rate in a family group determined by automatic monitoring].

Over a week, blood pressure (systolic, mean and diastolic) and heart rate were determined in a family, by means of automatic, uninterrupted monitoring. The chronobiological profile for each family member was prepared in time series of various periodicities. An ample circadian component and a lesser circaseptan component were apparent. Clear phase differences were identified among the four cardiovascular variables studied. The chronobiological profile of the children was closer to that of the father than to that of the mother.

Adolescent↗